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Sample records for arabidopsis freezing tolerance

  1. Transcriptional and metabolomic analysis of Ascophyllum nodosum mediated freezing tolerance in Arabidopsis thaliana

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    Nair Prasanth

    2012-11-01

    Full Text Available Abstract Background We have previously shown that lipophilic components (LPC of the brown seaweed Ascophyllum nodosum (ANE improved freezing tolerance in Arabidopsis thaliana. However, the mechanism(s of this induced freezing stress tolerance is largely unknown. Here, we investigated LPC induced changes in the transcriptome and metabolome of A. thaliana undergoing freezing stress. Results Gene expression studies revealed that the accumulation of proline was mediated by an increase in the expression of the proline synthesis genes P5CS1 and P5CS2 and a marginal reduction in the expression of the proline dehydrogenase (ProDH gene. Moreover, LPC application significantly increased the concentration of total soluble sugars in the cytosol in response to freezing stress. Arabidopsis sfr4 mutant plants, defective in the accumulation of free sugars, treated with LPC, exhibited freezing sensitivity similar to that of untreated controls. The 1H NMR metabolite profile of LPC-treated Arabidopsis plants exposed to freezing stress revealed a spectrum dominated by chemical shifts (δ representing soluble sugars, sugar alcohols, organic acids and lipophilic components like fatty acids, as compared to control plants. Additionally, 2D NMR spectra suggested an increase in the degree of unsaturation of fatty acids in LPC treated plants under freezing stress. These results were supported by global transcriptome analysis. Transcriptome analysis revealed that LPC treatment altered the expression of 1113 genes (5% in comparison with untreated plants. A total of 463 genes (2% were up regulated while 650 genes (3% were down regulated. Conclusion Taken together, the results of the experiments presented in this paper provide evidence to support LPC mediated freezing tolerance enhancement through a combination of the priming of plants for the increased accumulation of osmoprotectants and alteration of cellular fatty acid composition.

  2. Disruption of the Arabidopsis Defense Regulator Genes SAG101, EDS1, and PAD4 Confers Enhanced Freezing Tolerance.

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    Chen, Qin-Fang; Xu, Le; Tan, Wei-Juan; Chen, Liang; Qi, Hua; Xie, Li-Juan; Chen, Mo-Xian; Liu, Bin-Yi; Yu, Lu-Jun; Yao, Nan; Zhang, Jian-Hua; Shu, Wensheng; Xiao, Shi

    2015-10-01

    In Arabidopsis, three lipase-like regulators, SAG101, EDS1, and PAD4, act downstream of resistance protein-associated defense signaling. Although the roles of SAG101, EDS1, and PAD4 in biotic stress have been extensively studied, little is known about their functions in plant responses to abiotic stresses. Here, we show that SAG101, EDS1, and PAD4 are involved in the regulation of freezing tolerance in Arabidopsis. With or without cold acclimation, the sag101, eds1, and pad4 single mutants, as well as their double mutants, exhibited similarly enhanced tolerance to freezing temperatures. Upon cold exposure, the sag101, eds1, and pad4 mutants showed increased transcript levels of C-REPEAT/DRE BINDING FACTORs and their regulons compared with the wild type. Moreover, freezing-induced cell death and accumulation of hydrogen peroxide were ameliorated in sag101, eds1, and pad4 mutants. The sag101, eds1, and pad4 mutants had much lower salicylic acid (SA) and diacylglycerol (DAG) contents than the wild type, and exogenous application of SA and DAG compromised the freezing tolerance of the mutants. Furthermore, SA suppressed the cold-induced expression of DGATs and DGKs in the wild-type leaves. These findings indicate that SAG101, EDS1, and PAD4 are involved in the freezing response in Arabidopsis, at least in part, by modulating the homeostasis of SA and DAG.

  3. Natural variation in CBF gene sequence, gene expression and freezing tolerance in the Versailles core collection of Arabidopsis thaliana

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    Brunel Dominique

    2008-10-01

    Full Text Available Abstract Background Plants from temperate regions are able to withstand freezing temperatures due to a process known as cold acclimation, which is a prior exposure to low, but non-freezing temperatures. During acclimation, a large number of genes are induced, bringing about biochemical changes in the plant, thought to be responsible for the subsequent increase in freezing tolerance. Key regulatory proteins in this process are the CBF1, 2 and 3 transcription factors which control the expression of a set of target genes referred to as the "CBF regulon". Results To assess the role of the CBF genes in cold acclimation and freezing tolerance of Arabidopsis thaliana, the CBF genes and their promoters were sequenced in the Versailles core collection, a set of 48 accessions that maximizes the naturally-occurring genetic diversity, as well as in the commonly used accessions Col-0 and WS. Extensive polymorphism was found in all three genes. Freezing tolerance was measured in all accessions to assess the variability in acclimated freezing tolerance. The effect of sequence polymorphism was investigated by evaluating the kinetics of CBF gene expression, as well as that of a subset of the target COR genes, in a set of eight accessions with contrasting freezing tolerance. Our data indicate that CBF genes as well as the selected COR genes are cold induced in all accessions, irrespective of their freezing tolerance. Although we observed different levels of expression in different accessions, CBF or COR gene expression was not closely correlated with freezing tolerance. Conclusion Our results indicate that the Versailles core collection contains significant natural variation with respect to freezing tolerance, polymorphism in the CBF genes and CBF and COR gene expression. Although there tends to be more CBF and COR gene expression in tolerant accessions, there are exceptions, reinforcing the idea that a complex network of genes is involved in freezing tolerance

  4. A comparison of the low temperature transcriptomes and CBF regulons of three plant species that differ in freezing tolerance: Solanum commersonii, Solanum tuberosum, and Arabidopsis thaliana

    OpenAIRE

    Carvallo, Marcela A.; Pino, María-Teresa; Jeknić, Zoran; Zou, Cheng; Doherty, Colleen J.; Shiu, Shin-Han; Chen, Tony H. H.; Thomashow, Michael F.

    2011-01-01

    Solanum commersonii and Solanum tuberosum are closely related plant species that differ in their abilities to cold acclimate; whereas S. commersonii increases in freezing tolerance in response to low temperature, S. tuberosum does not. In Arabidopsis thaliana, cold-regulated genes have been shown to contribute to freezing tolerance, including those that comprise the CBF regulon, genes that are controlled by the CBF transcription factors. The low temperature transcriptomes and CBF regulons of ...

  5. Putrescine accumulation in Arabidopsis thaliana transgenic lines enhances tolerance to dehydration and freezing stress

    OpenAIRE

    Alet, Analía I; Sanchez, Diego H; Cuevas, Juan C.; del Valle, Secundino; Altabella, Teresa; Tiburcio, Antonio F.; Marco, Francisco; Ferrando, Alejandro; Espasandín, Fabiana D; María E. González; Carrasco, Pedro; Ruiz, Oscar A.

    2011-01-01

    Polyamines have been globally associated to plant responses to abiotic stress. Particularly, putrescine has been related to a better response to cold and dehydration stresses. It is known that this polyamine is involved in cold tolerance, since Arabidopsis thaliana plants mutated in the key enzyme responsible for putrescine synthesis (arginine decarboxilase, ADC; EC 4.1.1.19) are more sensitive than the wild type to this stress. Although it is speculated that the overexpression of ADC genes m...

  6. Overexpression of Arabidopsis NADPH-dependent thioredoxin reductase C (AtNTRC) confers freezing and cold shock tolerance to plants

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Jeong Chan [National Institute of Ecology, 1210 Geumgang-ro, Maseo-myeon, Seocheon-gun 325-813 (Korea, Republic of); Lee, Sangmin [Department of Biochemistry, College of Natural Sciences, Kangwon National University, Chuncheon (Korea, Republic of); Shin, Su Young [National Institute of Ecology, 1210 Geumgang-ro, Maseo-myeon, Seocheon-gun 325-813 (Korea, Republic of); Chae, Ho Byoung; Jung, Young Jun [Division of Applied Life Science - BK21+ program, PMBBRC, Gyeongsang National University, Jinju (Korea, Republic of); Jung, Hyun Suk [Department of Biochemistry, College of Natural Sciences, Kangwon National University, Chuncheon (Korea, Republic of); Lee, Kyun Oh [Division of Applied Life Science - BK21+ program, PMBBRC, Gyeongsang National University, Jinju (Korea, Republic of); Lee, Jung Ro, E-mail: leejr73@nie.re.kr [National Institute of Ecology, 1210 Geumgang-ro, Maseo-myeon, Seocheon-gun 325-813 (Korea, Republic of); Department of Biochemistry and Biophysics, Texas A& M University, College Station, TX (United States); Lee, Sang Yeol, E-mail: sylee@gnu.ac.kr [Division of Applied Life Science - BK21+ program, PMBBRC, Gyeongsang National University, Jinju (Korea, Republic of)

    2015-08-07

    Overexpression of AtNTRC (AtNTRC{sup OE}) in Arabidopsis thaliana led to a freezing and cold stress tolerance, whereas a knockout mutant (atntrc) showed a stress-sensitive phenotype. Biochemical analyses showed that the recombinant AtNTRC proteins exhibited a cryoprotective activity for malate dehydrogenase and lactic dehydrogenase. Furthermore, conclusive evidence of its interaction with nucleic acids in vitro is provided here on the basis of gel shift and electron microscopy analysis. Recombinant AtNTRC efficiently protected RNA and DNA from RNase A and metal catalyzed oxidation damage, respectively. The C-terminal thioredoxin domain is required for the nucleic acid–protein complex formation. From these results, it can be hypothesized that AtNTRC, which is known to be an electron donor of peroxiredoxin, contributes the stability of macromolecules under cold stress. - Highlights: • AtNTRC has a cryoprotective activity in vitro. • Overexpression of AtNTRC increases tolerance to freezing and cold shock stresses. • Thioredoxin domain of AtNTRC protects nucleic acids in vitro. • AtNTRC inhibits protein aggregation under freezing stress in vitro.

  7. Starch-related alpha-glucan/water dikinase is involved in the cold-induced development of freezing tolerance in Arabidopsis.

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    Yano, Ryoichi; Nakamura, Masanobu; Yoneyama, Tadakatsu; Nishida, Ikuo

    2005-06-01

    Cold-induced soluble sugar accumulation enhances the degree of freezing tolerance in various cold-hardy plants including Arabidopsis (Arabidopsis thaliana), where soluble sugars accumulate in only a few hours at 2 degrees C. Hence, along with photosynthesis, starch degradation might play a significant role in cold-induced sugar accumulation and enhanced freezing tolerance. Starch-related alpha-glucan/water dikinase (EC 2.7.9.4), encoded by Arabidopsis STARCH EXCESS 1 (SEX1), is hypothesized to regulate starch degradation in plastids by phosphorylating starch, thereby ensuring better accessibility by starch-degrading enzymes. Here, we show that Arabidopsis sex1 mutants, when incubated at 2 degrees C for 1 d, were unable to accumulate maltooligosaccharides or normal glucose and fructose levels. In addition, they displayed impaired freezing tolerance. After 7 d at 2 degrees C, sex1 mutants did not show any of the above abnormal phenotypes but displayed slightly higher leaf starch contents. The impaired freezing tolerance of sex1 mutants was restored by overexpression of wild-type SEX1 cDNA using the cauliflower mosaic virus 35S promoter. The results demonstrate a genetic link between the SEX1 locus and plant freezing tolerance, and show that starch degradation is important for enhanced freezing tolerance during an early phase of cold acclimation. However, induction of starch degradation was not accompanied by significant changes in alpha-glucan/water dikinase activity in leaf extracts and preceded cold-induced augmentation of SEX1 transcripts. Therefore, we conclude that augmentation of SEX1 transcripts might be a homeostatic response to low temperature, and that starch degradation during an early phase of cold acclimation could be regulated by a component(s) of a starch degradation pathway(s) downstream of SEX1.

  8. JcCBF2 gene from Jatropha curcas improves freezing tolerance of Arabidopsis thaliana during the early stage of stress.

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    Wang, Linghui; Gao, Jihai; Qin, Xiaobo; Shi, Xiaodong; Luo, Lin; Zhang, Guozhen; Yu, Hongwu; Li, Chenyang; Hu, Minchao; Liu, Qifan; Xu, Ying; Chen, Fang

    2015-05-01

    High chilling-susceptibility is becoming the bottleneck for cultivation and commercialization of Jatropha curcas L. For insights to chilling resistance ability of this plant species, a cold response transcription factor, JcCBF2, was cloned and studied. It codes a 26 kDa protein, which contains all conserved motifs unique to the C-repeat binding factor (CBF) family and has high similarity to CBFs of Ricinus communis and Populus. Its transcripts express specifically in leaves of Jatropha at cold temperature. After transmitting the report vector, 35S::JcCBF2-GFP, into Arabidopsis thaliana, JcCBF2 protein is main detected in cell nucleus, being consistent to the nuclear orientation signal in its N-terminal. Compared to the control Arabidopsis, the frozen leaves of JcCBF2-overexpressed seedlings grow stronger with less malondialdehyde, smaller leaf conductivity and activer superoxide dismutase, showing their higher freezing tolerance. RT-PCR tests revealed that JcCBF2 functioned mainly at the early stage (0-6 h) of resistance events in Arabidopsis, and its transcripts reduced after 6 h. In addition, JcCBF2 could quickly regulate transcripts of some cold-responsive (COR) genes such as RD29A, COR105A and COR6.6, also during the early stage of frozen treatment. This study not only proves the chilling resistance roles of JcCBF2, but also presents a candidate gene engineering for improvement of chilling tolerance in J. curcas.

  9. Putrescine accumulation in Arabidopsis thaliana transgenic lines enhances tolerance to dehydration and freezing stress.

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    Alet, Analía I; Sanchez, Diego H; Cuevas, Juan C; Del Valle, Secundino; Altabella, Teresa; Tiburcio, Antonio F; Marco, Francisco; Ferrando, Alejandro; Espasandín, Fabiana D; González, María E; Ruiz, Oscar A; Carrasco, Pedro

    2011-02-01

    Polyamines have been globally associated to plant responses to abiotic stress. Particularly, putrescine has been related to a better response to cold and dehydration stresses. It is known that this polyamine is involved in cold tolerance, since Arabidopsis thaliana plants mutated in the key enzyme responsible for putrescine synthesis (arginine decarboxilase, ADC; EC 4.1.1.19) are more sensitive than the wild type to this stress. Although it is speculated that the over-expression of ADC genes may confer tolerance, this is hampered by pleiotropic effects arising from the constitutive expression of enzymes from the polyamine metabolism. Here, we present our work using A. thaliana transgenic plants harboring the ADC gene from oat under the control of a stress-inducible promoter (pRD29A) instead of a constitutive promoter. The transgenic lines presented in this work were more resistant to both cold and dehydration stresses, associated with a concomitant increment in endogenous putrescine levels under stress. Furthermore, the increment in putrescine upon cold treatment correlated with the induction of known stress-responsive genes, and suggested that putrescine may be directly or indirectly involved in ABA metabolism and gene expression.

  10. A comparison of the low temperature transcriptomes and CBF regulons of three plant species that differ in freezing tolerance: Solanum commersonii, Solanum tuberosum, and Arabidopsis thaliana.

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    Carvallo, Marcela A; Pino, María-Teresa; Jeknic, Zoran; Zou, Cheng; Doherty, Colleen J; Shiu, Shin-Han; Chen, Tony H H; Thomashow, Michael F

    2011-07-01

    Solanum commersonii and Solanum tuberosum are closely related plant species that differ in their abilities to cold acclimate; whereas S. commersonii increases in freezing tolerance in response to low temperature, S. tuberosum does not. In Arabidopsis thaliana, cold-regulated genes have been shown to contribute to freezing tolerance, including those that comprise the CBF regulon, genes that are controlled by the CBF transcription factors. The low temperature transcriptomes and CBF regulons of S. commersonii and S. tuberosum were therefore compared to determine whether there might be differences that contribute to their differences in ability to cold acclimate. The results indicated that both plants alter gene expression in response to low temperature to similar degrees with similar kinetics and that both plants have CBF regulons composed of hundreds of genes. However, there were considerable differences in the sets of genes that comprised the low temperature transcriptomes and CBF regulons of the two species. Thus differences in cold regulatory programmes may contribute to the differences in freezing tolerance of these two species. However, 53 groups of putative orthologous genes that are cold-regulated in S. commersonii, S. tuberosum, and A. thaliana were identified. Given that the evolutionary distance between the two Solanum species and A. thaliana is 112-156 million years, it seems likely that these conserved cold-regulated genes-many of which encode transcription factors and proteins of unknown function-have fundamental roles in plant growth and development at low temperature.

  11. A comparison of the low temperature transcriptomes and CBF regulons of three plant species that differ in freezing tolerance: Solanum commersonii, Solanum tuberosum, and Arabidopsis thaliana

    Science.gov (United States)

    Pino, María-Teresa; Jeknić, Zoran; Zou, Cheng; Shiu, Shin-Han; Chen, Tony H. H.; Thomashow, Michael F.

    2011-01-01

    Solanum commersonii and Solanum tuberosum are closely related plant species that differ in their abilities to cold acclimate; whereas S. commersonii increases in freezing tolerance in response to low temperature, S. tuberosum does not. In Arabidopsis thaliana, cold-regulated genes have been shown to contribute to freezing tolerance, including those that comprise the CBF regulon, genes that are controlled by the CBF transcription factors. The low temperature transcriptomes and CBF regulons of S. commersonii and S. tuberosum were therefore compared to determine whether there might be differences that contribute to their differences in ability to cold acclimate. The results indicated that both plants alter gene expression in response to low temperature to similar degrees with similar kinetics and that both plants have CBF regulons composed of hundreds of genes. However, there were considerable differences in the sets of genes that comprised the low temperature transcriptomes and CBF regulons of the two species. Thus differences in cold regulatory programmes may contribute to the differences in freezing tolerance of these two species. However, 53 groups of putative orthologous genes that are cold-regulated in S. commersonii, S. tuberosum, and A. thaliana were identified. Given that the evolutionary distance between the two Solanum species and A. thaliana is 112–156 million years, it seems likely that these conserved cold-regulated genes—many of which encode transcription factors and proteins of unknown function—have fundamental roles in plant growth and development at low temperature. PMID:21511909

  12. Putrescine Is Involved in Arabidopsis Freezing Tolerance and Cold Acclimation by Regulating Abscisic Acid Levels in Response to Low Temperature1

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    Cuevas, Juan C.; López-Cobollo, Rosa; Alcázar, Rubén; Zarza, Xavier; Koncz, Csaba; Altabella, Teresa; Salinas, Julio; Tiburcio, Antonio F.; Ferrando, Alejandro

    2008-01-01

    The levels of endogenous polyamines have been shown to increase in plant cells challenged with low temperature; however, the functions of polyamines in the regulation of cold stress responses are unknown. Here, we show that the accumulation of putrescine under cold stress is essential for proper cold acclimation and survival at freezing temperatures because Arabidopsis (Arabidopsis thaliana) mutants defective in putrescine biosynthesis (adc1, adc2) display reduced freezing tolerance compared to wild-type plants. Genes ADC1 and ADC2 show different transcriptional profiles upon cold treatment; however, they show similar and redundant contributions to cold responses in terms of putrescine accumulation kinetics and freezing sensitivity. Our data also demonstrate that detrimental consequences of putrescine depletion during cold stress are due, at least in part, to alterations in the levels of abscisic acid (ABA). Reduced expression of NCED3, a key gene involved in ABA biosynthesis, and down-regulation of ABA-regulated genes are detected in both adc1 and adc2 mutant plants under cold stress. Complementation analysis of adc mutants with ABA and reciprocal complementation tests of the aba2-3 mutant with putrescine support the conclusion that putrescine controls the levels of ABA in response to low temperature by modulating ABA biosynthesis and gene expression. PMID:18701673

  13. Cold-inducible expression of AZI1 and its function in improvement of freezing tolerance of Arabidopsis thaliana and Saccharomyces cerevisiae.

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    Xu, Zhi-Yan; Zhang, Xin; Schläppi, Michael; Xu, Zi-Qin

    2011-09-01

    AZI1 (AZELAIC ACID INDUCED 1) of Arabidopsis thaliana could be induced by azelaic acid and was involved in priming of systemic plant immunity. In the present work, expression of AZI1 in response to low temperature was investigated via RNA gel blot analysis. AZI1 could be induced slowly by cold stress and more than 6h treatment at 4°C was required to detect an increase in mRNA abundance. However, the high expression state could not be maintained stably and would decline to basal level when the plants were transferred to room temperature. In order to clarify the function of AZI1 in resistance to abiotic stresses, overexpressing, RNA interference and T-DNA knockout lines of this gene were used in electrolyte leakage assays. Overexpression of AZI1 resulted in reduced electrolyte leakage during freezing damage. In contrast, AZI1 knockdown and knockout lines showed increased tendencies in cellular damage after freezing treatment. To further validate the potential resistance of AZI1 to low-temperature stress, Saccharomyces cerevisiae cells were transformed with pESC-AZI1 in which AZI1 was under the control of GAL1 promoter. Compared to yeast cells containing empty pESC-URA, the survival rate of yeast cells harboring AZI1 increased obviously after freezing treatment. All these results suggested that AZI1 might be multifunctional and associated with cold tolerance of Arabidopsis.

  14. A novel Zea mays ssp. mexicana L. MYC-type ICE-like transcription factor gene ZmmICE1, enhances freezing tolerance in transgenic Arabidopsis thaliana.

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    Lu, Xiang; Yang, Lei; Yu, Mengyuan; Lai, Jianbin; Wang, Chao; McNeil, David; Zhou, Meixue; Yang, Chengwei

    2017-04-01

    The annual Zea mays ssp. mexicana L., a member of the teosinte group, is a close wild relative of maize and thus can be effectively used in maize improvement. In this study, an ICE-like gene, ZmmICE1, was isolated from a cDNA library of RNA-Seq from cold-treated seedling tissues of Zea mays ssp. mexicana L. The deduced protein of ZmmICE1 contains a highly conserved basic helix-loop-helix (bHLH) domain and C-terminal region of ICE-like proteins. The ZmmICE1 protein localizes to the nucleus and shows sumoylation when expressed in an Escherichia coli reconstitution system. In addition, yeast one hybrid assays indicated that ZmmICE1 has transactivation activities. Moreover, ectopic expression of ZmmICE1 in the Arabidopsis ice1-2 mutant increased freezing tolerance. The ZmmICE1 overexpressed plants showed lower electrolyte leakage (EL), reduced contents of malondialdehyde (MDA). The expression of downstream cold related genes of Arabidopsis C-repeat-binding factors (AtCBF1, AtCBF2 and AtCBF3), cold-responsive genes (AtCOR15A and AtCOR47), kinesin-1 member gene (AtKIN1) and responsive to desiccation gene (AtRD29A) was significantly induced when compared with wild type under low temperature treatment. Taken together, these results indicated that ZmmICE1 is the homolog of Arabidopsis inducer of CBF expression genes (AtICE1/2) and plays an important role in the regulation of freezing stress response.

  15. Characterization of three Arabidopsis AP2/EREBP family transcription factors involved in ABA sensitivity,freeze and salt tolerance

    Institute of Scientific and Technical Information of China (English)

    MEI WenQian; LEI Juan; Xu Yu; WEI Gang; ZHU YuXian

    2007-01-01

    AP2/EREBP transcription factors (TFs) play very important roles in plant development,hormonal regulation and stress response. Upon genome-wide cDNA cloning,phylogenetic and expression pattern analyses of this plant specific TF family,we found that three of the members including At1g71450,At1g50680 and At5g13910,were likely involved in responses to ABA,cold and salt. Complementary DNAs containing putative full-length ORFs of these three TFs were obtained and fused individually to the GAL4 DNA-binding domains. All the 3 genes functioned effectively as trans-activators using yeast one-hybrid assays. RT-PCR experiments showed that the At1g71450 gene was induced by ABA and low temperature; the At1g50680 gene was responsive to quite a few stress conditions,but especially to freezing temperature; and the At5g13910 gene was induced by high salt treatment,drought and ethylene. By searching the ABRC T-DNA insertion mutant stocks,we obtained knockout lines for these TFs. Homozygous ko1 (At1g71450) plants showed a hypersensitive response to ABA during seed germination and also in stomata movement. Homozygous ko2 (At1g50680) plants showed a significant reduction in plant freezing tolerance compared to the wild type after chilling treatment. Homozygous ko3 (At5g13910) were less tolerant to high salinity than wild type plants. Our data suggest that At1g71450 is a negative regulator in ABA signaling,while At1g50680 and At5g13910 are positive regulators in cold and salt stress responses,respectively.

  16. Anhydrobiosis and Freezing-Tolerance

    DEFF Research Database (Denmark)

    McGill, Lorraine; Shannon, Adam; Pisani, Davide

    2015-01-01

    Anhydrobiotic animals can survive the loss of both free and bound water from their cells. While in this state they are also resistant to freezing. This physiology adapts anhydrobiotes to harsh environments and it aids their dispersal. Panagrolaimus davidi, a bacterial feeding anhydrobiotic nematode...... isolated from Ross Island Antarctica, can survive intracellular ice formation when fully hydrated. A capacity to survive freezing while fully hydrated has also been observed in some other Antarctic nematodes. We experimentally determined the anhydrobiotic and freezing-tolerance phenotypes of 24...... of the davidi and the superbus clades were anhydrobiotic and also possessed robust freezing tolerance, along with a capacity to inhibit the growth and recrystallization of ice crystals. Unlike other endemic Antarctic nematodes, the life history traits of P. davidi do not show evidence of an evolved response...

  17. Over-expression of JcDREB, a putative AP2/EREBP domain-containing transcription factor gene in woody biodiesel plant Jatropha curcas, enhances salt and freezing tolerance in transgenic Arabidopsis thaliana.

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    Tang, Mingjuan; Liu, Xiaofei; Deng, Huaping; Shen, Shihua

    2011-12-01

    Jatropha curcas L. is an all-purpose biodiesel plant and is widely distributed in tropical and subtropical climates. It can grow well on poor quality soil which is not qualified for crop cultivation. This is very important for relieving land, food and energy crises. However, tropical and subtropical distribution limits the production of J. curcas seed. So it is valuable to know the molecular mechanism of J. curcas response to adverse abiotic environmental factors, especially freezing stress, in order to change the plant's characteristics. Until now there are just a few reports about J. curcas molecular biology. In this paper, we cloned and characterized a DNA binding protein from this plant, designated as JcDREB. Sequence analysis and yeast one-hybrid assays show that JcDREB can effectively function as a transcription factor of DREB protein family belonging to A-6 subgroup member. Expression patterns of JcDREB showed that it was induced by cold, salt and drought stresses, not by ABA. Over-expression of JcDREB in transgenic Arabidopsis exhibited enhanced salt and freezing stresses. Understanding the molecular mechanisms of J. curcas responses to environmental stresses, for example, high salinity, drought and low temperature, is crucial for improving their stress tolerance and productivity. This work provides more information about A-6 subgroup members of DREB subfamily.

  18. Potential role of salicylic acid in modulating diacylglycerol homeostasis in response to freezing temperatures in Arabidopsis.

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    Tan, Wei-Juan; Xiao, Shi; Chen, Qin-Fang

    2015-01-01

    In our recent article in Molecular Plant, we reported that 3 lipase-like defense regulators SENESCENCE-ASSOCIATED GENE101 (SAG101), ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1) and PHYTOALEXIN DEFICIENT4 (PAD4) are involved in the regulation of freezing tolerance in Arabidopsis. The transcripts of SAG101, EDS1 and PAD4 were inducible by cold stress and their knockout or knockdown mutants exhibited enhanced chilling and freezing tolerance in comparison to the wild type. The freezing tolerance phenotype showed in the sag101, eds1 and pad4 mutants was correlated with the transcriptional upregulation of C-REPEAT/DRE BINDING FACTORs (CBFs) and their regulons as well as increased levels of proline. Upon cold exposure, the sag101, eds1 and pad4 mutants showed ameliorated cell death and accumulation of hydrogen peroxide, which were highly induced by freezing stress in the wild-type leaves. Moreover, the contents of salicylic acid (SA) and diacylglycerol (DAG) were significantly decreased in the sag101, eds1 and pad4 mutants compared to the wild type. Taken together, our results suggest that the SAG101, EDS1 and PAD4 are negative regulators in the freezing response and function, at least in part, by modulating the homeostasis of SA and DAG in Arabidopsis.

  19. DOES GLUTATHIONE PLAY A ROLE IN FREEZING TOLERANCE OF PLANTS

    NARCIS (Netherlands)

    Stuiver, C.E.E.; De Kok, Luit J.; Kuiper, P.J.C.

    1992-01-01

    During low temperature hardening enhanced levels of glutathione (GSH) are generally observed in plant shoots and are often related to the development of freezing tolerance. The present communication shows that there is no direct relation between an increased GSH content and freezing tolerance of lea

  20. Burkholderia phytofirmans PsJN reduces damages to freezing temperature in Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Fan eSU

    2015-10-01

    Full Text Available Several plant growth-promoting rhizobacteria (PGPR are known to improve plant tolerance to multiple stresses, including low temperatures. However, mechanisms underlying this protection are still poorly understood. The aim of this study was to evaluate the role of the endophytic PGPR, Burkholderia phytofirmans strain PsJN (Bp PsJN, on Arabidopsis thaliana cold tolerance using photosynthesis parameters as physiological markers.Under standard conditions, our results indicated that Bp PsJN inoculation led to growth promotion of Arabidopsis plants without significant modification on photosynthesis parameters and chloroplast organization. However, bacterial colonization induced a cell wall strengthening in the mesophyllImpact of inoculation modes (either on seeds or by soil irrigation and their effects overnight at 0, -1 or -3°C, were investigated by following photosystem II (PSII activity and gas exchanges. Following low temperatures stress, a decrease of photosynthesis parameters was observed. In addition, during three consecutive nights or days at -1°C, PSII activity was monitored. Pigment contents, RuBisCO protein abundance, expression of several genes including RbcS, RbcL, CBF1, CBF2, CBF3, ICE1, COR15a, and COR78 were evaluated at the end of exposure. To assess the impact of the bacteria on cell ultrastructure under low temperatures, microscopic observations were achieved. Results indicated that freezing treatment induced significant changes in PSII activity as early as the first cold day, whereas the same impact on PSII activity was observed only during the third cold night. The significant effects conferred by PsJN were differential accumulation of pigments, and reduced expression of RbcL and COR78. Microscopical observations showed an alteration/disorganization in A. thaliana leaf mesophyll cells independently of the freezing treatments. The presence of bacteria during the three successive nights or days did not significantly improved A

  1. Freezing tolerance of winter wheat as influenced by extended growth at low temperature and exposure to freeze-thaw cycles

    Science.gov (United States)

    As the seasons progress, autumn-planted winter wheat plants (Triticum aestivum L.) first gain, then progressively lose freezing tolerance. Exposing the plants to freeze-thaw cycles of -3/3°C results in increased ability to tolerate subsequent freezing to potentially damaging temperatures. This stu...

  2. Overexpression of a proton-coupled vacuolar glucose exporter impairs freezing tolerance and seed germination.

    Science.gov (United States)

    Klemens, Patrick A W; Patzke, Kathrin; Trentmann, Oliver; Poschet, Gernot; Büttner, Michael; Schulz, Alexander; Marten, Irene; Hedrich, Rainer; Neuhaus, H Ekkehard

    2014-04-01

    Arabidopsis vacuoles harbor, besides sugar transporter of the TMT-type, an early response to dehydration like 6 (ERDL6) protein involved in glucose export into the cytosol. However, the mode of transport of ERDL6 and the plant's feedback to overexpression of its activity on essential properties such as, for example, seed germination or freezing tolerance, remain unexplored. Using patch-clamp studies on vacuoles expressing AtERDL6 we demonstrated directly that this carrier operates as a proton-driven glucose exporter. Overexpression of BvIMP, the closest sugar beet (Beta vulgaris) homolog to AtERDL6, in Arabidopsis leads surprisingly to impaired seed germination under both conditions, sugar application and low environmental temperatures, but not under standard conditions. Upon cold treatment, BvIMP overexpressor plants accumulated lower quantities of monosaccharides than the wild-type, a response in line with the reduced frost tolerance of the transgenic Arabidopsis plants, and the fact that cold temperatures inhibits BvIMP transcription in sugar beet leaves. With these findings we show that the tight control of vacuolar sugar import and export is a key requisite for cold tolerance and seed germination of plants.

  3. Engineering carpel-specific cold stress tolerance: a case study in Arabidopsis.

    Science.gov (United States)

    Artlip, Timothy S; Wisniewski, Michael E; Takatsuji, Hiroshi; Bassett, Carole L

    2016-08-01

    Climate change predictions forecast an increase in early spring frosts that could result in severe damage to perennial crops. For example, the Easter freeze of April 2007 left several states in the United States reporting a complete loss of that year's peach crop. The most susceptible organ to early frost damage in fruit trees is the carpel, particularly during bloom opening. In this study, we explored the use of a carpel-specific promoter (ZPT2-10) from petunia (Petunia hybrida var. Mitchell) to drive expression of the peach dehydrin PpDhn1. In peach, this gene is exceptionally responsive to low temperature but has not been observed to be expressed in carpels. This study examined carpel-specific properties of a petunia promoter driving the expression of the GUS gene (uidA) in transgenic Arabidopsis flowers and developed a carpel-specific ion leakage test to assess freezing tolerance. A homozygous Arabidopsis line (line 1-20) carrying the petunia ZPT2-10 promoter::PpDhn1 construct was obtained and freezing tolerance in the transgenic line was compared with an untransformed control. Overexpression of PpDhn1 in line 1-20 provided as much as a 1.9°C increase in carpel freezing tolerance as measured by electrolyte leakage.

  4. Regulation of SMAD transcription factors during freezing in the freeze tolerant wood frog, Rana sylvatica.

    Science.gov (United States)

    Aguilar, Oscar A; Hadj-Moussa, Hanane; Storey, Kenneth B

    2016-11-01

    The wood frog, Rana sylvatica, survives sub-zero winter temperatures by undergoing full body freezing for weeks at a time, during which it displays no measurable brain activity, no breathing, and a flat-lined heart. Freezing is a hypometabolic state characterized by a global suppression of gene expression that is elicited in part by transcription factors that coordinate the activation of vital pro-survival pathways. Smad transcription factors respond to TGF-β signalling and are involved in numerous cellular functions from development to stress. Given the identity of genes they regulate, we hypothesized that they may be involved in coordinating gene expression during freezing. Protein expression of Smad1/2/3/4/5 in response to freezing was examined in 24h frozen and 8h thawed wood frog tissues using western immunoblotting, with the determination of subcellular localization in muscle and liver tissues. Transcript levels of smad2, smad4 and downstream genes (serpine1, myostatin, and tsc22d3) were measured by RT-PCR. Tissue-specific responses were observed during freezing where brain, heart, and liver had elevated levels of pSmad3, and skeletal muscle and kidneys had increased levels of pSmad1/5 and pSmad2 during freeze/thaw cycle, while protein and transcript levels remained constant. There were increases in nuclear levels of pSmad2 in muscle and pSmad3 in liver. Transcript levels of serpine1 were induced in heart, muscle, and liver, myostatin in muscle, and tsc22d3 in heart, and liver during freezing. These results suggest a novel freeze-responsive activation of Smad proteins that may play an important role in coordinating pro-survival gene networks necessary for freeze tolerance.

  5. Air-Cooled Stack Freeze Tolerance Freeze Failure Modes and Freeze Tolerance Strategies for GenDriveTM Material Handling Application Systems and Stacks Final Scientific Report

    Energy Technology Data Exchange (ETDEWEB)

    Hancock, David, W.

    2012-02-14

    Air-cooled stack technology offers the potential for a simpler system architecture (versus liquid-cooled) for applications below 4 kilowatts. The combined cooling and cathode air allows for a reduction in part count and hence a lower cost solution. However, efficient heat rejection challenges escalate as power and ambient temperature increase. For applications in ambient temperatures below freezing, the air-cooled approach has additional challenges associated with not overcooling the fuel cell stack. The focus of this project was freeze tolerance while maintaining all other stack and system requirements. Through this project, Plug Power advanced the state of the art in technology for air-cooled PEM fuel cell stacks and related GenDrive material handling application fuel cell systems. This was accomplished through a collaborative work plan to improve freeze tolerance and mitigate freeze-thaw effect failure modes within innovative material handling equipment fuel cell systems designed for use in freezer forklift applications. Freeze tolerance remains an area where additional research and understanding can help fuel cells to become commercially viable. This project evaluated both stack level and system level solutions to improve fuel cell stack freeze tolerance. At this time, the most cost effective solutions are at the system level. The freeze mitigation strategies developed over the course of this project could be used to drive fuel cell commercialization. The fuel cell system studied in this project was Plug Power's commercially available GenDrive platform providing battery replacement for equipment in the material handling industry. The fuel cell stacks were Ballard's commercially available FCvelocity 9SSL (9SSL) liquid-cooled PEM fuel cell stack and FCvelocity 1020ACS (Mk1020) air-cooled PEM fuel cell stack.

  6. FREEZING TOLERANCE AND BIOCHEMICAL-CHANGES IN WHEAT SHOOTS AS AFFECTED BY H2S FUMIGATION

    NARCIS (Netherlands)

    Stuiver, C.E.E.; De Kok, Luit J.; Kuiper, P.J.C.

    1992-01-01

    Fumigation of winter wheat with H2S during low temperature acclimation substantially reduced the development of freezing tolerance of the leaves. After 6 weeks of low temperature exposure (3-degrees-C), the freezing tolerance was increased by 6 and 2-degrees-C at 0 and 0.25-mu-l l-1 H2S, respectivel

  7. Cold tolerance and freeze-induced glucose accumulation in three terrestrial slugs

    DEFF Research Database (Denmark)

    Slotsbo, Stine; Hansen, Lars Monrad; Jordaens, Kurt;

    2012-01-01

    in their habitat. Slugs spontaneously froze at about -4 °C when cooled under dry conditions, but freezing of body fluids was readily induced at -1 °C when in contact with external ice crystals. All three species survived freezing for 2 days at -1 °C, and some A. rufus and A. lusitanicus also survived freezing......Cold tolerance and metabolic responses to freezing of three slug species common in Scandinavia (Arion ater, Arion rufus and Arion lusitanicus) are reported. Autumn collected slugs were cold acclimated in the laboratory and subjected to freezing conditions simulating likely winter temperatures....... Glucose increased from about 6 to 22 µg/mg dry tissue upon freezing in A. rufus, but less so in A. ater and A. lusitanicus. Glucose may thus act as a cryoprotectant in these slugs, although the concentrations are not as high as reported for other freeze tolerant invertebrates....

  8. Improvement of tolerance to freeze-thaw stress of baker's yeast by cultivation with soy peptides.

    Science.gov (United States)

    Izawa, Shingo; Ikeda, Kayo; Takahashi, Nobuyuki; Inoue, Yoshiharu

    2007-06-01

    The tolerance to freeze-thaw stress of yeast cells is critical for frozen-dough technology in the baking industry. In this study, we examined the effects of soy peptides on the freeze-thaw stress tolerance of yeast cells. We found that the cells cultured with soy peptides acquired improved tolerance to freeze-thaw stress and retained high leavening ability in dough after frozen storage for 7 days. The final quality of bread regarding its volume and texture was also improved by using yeast cells cultured with soy peptides. These findings promote the utilization of soy peptides as ingredients of culture media to improve the quality of baker's yeast.

  9. The oatmeal nematode Panagrellus redivivus survives moderately low temperatures by freezing tolerance and cryoprotective dehydration.

    Science.gov (United States)

    Hayashi, Masakazu; Wharton, David A

    2011-04-01

    The cold tolerance abilities of only a few nematode species have been determined. This study shows that the oatmeal nematode, Panagrellus redivivus, has modest cold tolerance with a 50% survival temperature (S (50)) of -2.5°C after cooling at 0.5°C min(-1) and freezing for 1 h. It can survive low temperatures by freezing tolerance and cryoprotective dehydration; although freezing tolerance appears to be the dominant strategy. Freezing survival is enhanced by low temperature acclimation (7 days at 5°C), with the S (50) being lowered by a small but significant amount (0.42°C). There is no cold shock or rapid cold hardening response under the conditions tested. Cryoprotective dehydration enhances the ability to survive freezing (the S (50) is lowered by 0.55°C, compared to the control, after 4 h freezing at -1°C) and this effect is in addition to that produced by acclimation. Breeding from survivors of a freezing stress did not enhance the ability to survive freezing. The cold tolerance abilities of this nematode are modest, but sufficient to enable it to survive in the cold temperate environments it inhabits.

  10. Anhydrobiosis and freezing-tolerance: adaptations that facilitate the establishment of Panagrolaimus nematodes in polar habitats.

    Directory of Open Access Journals (Sweden)

    Lorraine M McGill

    Full Text Available Anhydrobiotic animals can survive the loss of both free and bound water from their cells. While in this state they are also resistant to freezing. This physiology adapts anhydrobiotes to harsh environments and it aids their dispersal. Panagrolaimus davidi, a bacterial feeding anhydrobiotic nematode isolated from Ross Island Antarctica, can survive intracellular ice formation when fully hydrated. A capacity to survive freezing while fully hydrated has also been observed in some other Antarctic nematodes. We experimentally determined the anhydrobiotic and freezing-tolerance phenotypes of 24 Panagrolaimus strains from tropical, temperate, continental and polar habitats and we analysed their phylogenetic relationships. We found that several other Panagrolaimus isolates can also survive freezing when fully hydrated and that tissue extracts from these freezing-tolerant nematodes can inhibit the growth of ice crystals. We show that P. davidi belongs to a clade of anhydrobiotic and freezing-tolerant panagrolaimids containing strains from temperate and continental regions and that P. superbus, an early colonizer at Surtsey island, Iceland after its volcanic formation, is closely related to a species from Pennsylvania, USA. Ancestral state reconstructions show that anhydrobiosis evolved deep in the phylogeny of Panagrolaimus. The early-diverging Panagrolaimus lineages are strongly anhydrobiotic but weakly freezing-tolerant, suggesting that freezing tolerance is most likely a derived trait. The common ancestors of the davidi and the superbus clades were anhydrobiotic and also possessed robust freezing tolerance, along with a capacity to inhibit the growth and recrystallization of ice crystals. Unlike other endemic Antarctic nematodes, the life history traits of P. davidi do not show evidence of an evolved response to polar conditions. Thus we suggest that the colonization of Antarctica by P. davidi and of Surtsey by P. superbus may be examples of recent

  11. Anhydrobiosis and freezing-tolerance: adaptations that facilitate the establishment of Panagrolaimus nematodes in polar habitats.

    Science.gov (United States)

    McGill, Lorraine M; Shannon, Adam J; Pisani, Davide; Félix, Marie-Anne; Ramløv, Hans; Dix, Ilona; Wharton, David A; Burnell, Ann M

    2015-01-01

    Anhydrobiotic animals can survive the loss of both free and bound water from their cells. While in this state they are also resistant to freezing. This physiology adapts anhydrobiotes to harsh environments and it aids their dispersal. Panagrolaimus davidi, a bacterial feeding anhydrobiotic nematode isolated from Ross Island Antarctica, can survive intracellular ice formation when fully hydrated. A capacity to survive freezing while fully hydrated has also been observed in some other Antarctic nematodes. We experimentally determined the anhydrobiotic and freezing-tolerance phenotypes of 24 Panagrolaimus strains from tropical, temperate, continental and polar habitats and we analysed their phylogenetic relationships. We found that several other Panagrolaimus isolates can also survive freezing when fully hydrated and that tissue extracts from these freezing-tolerant nematodes can inhibit the growth of ice crystals. We show that P. davidi belongs to a clade of anhydrobiotic and freezing-tolerant panagrolaimids containing strains from temperate and continental regions and that P. superbus, an early colonizer at Surtsey island, Iceland after its volcanic formation, is closely related to a species from Pennsylvania, USA. Ancestral state reconstructions show that anhydrobiosis evolved deep in the phylogeny of Panagrolaimus. The early-diverging Panagrolaimus lineages are strongly anhydrobiotic but weakly freezing-tolerant, suggesting that freezing tolerance is most likely a derived trait. The common ancestors of the davidi and the superbus clades were anhydrobiotic and also possessed robust freezing tolerance, along with a capacity to inhibit the growth and recrystallization of ice crystals. Unlike other endemic Antarctic nematodes, the life history traits of P. davidi do not show evidence of an evolved response to polar conditions. Thus we suggest that the colonization of Antarctica by P. davidi and of Surtsey by P. superbus may be examples of recent "ecological fitting

  12. Importance of freeze-thaw events in low temperature ecotoxicology of cold tolerant enchytraeids.

    Science.gov (United States)

    Silva, Ana L Patrício; Enggrob, Kirsten; Slotsbo, Stine; Amorim, Mónica J B; Holmstrup, Martin

    2014-08-19

    Due to global warming it is predicted that freeze-thaw cycles will increase in Arctic and cold temperate regions. The effects of this variation becomes of particular ecological importance to freeze-tolerant species when it is combined with chemical pollutants. We compared the effect of control temperature (2 °C), daily freeze-thaw cycles (2 to -4 °C) and constant freezing (-2 °C) temperatures on the cold-tolerance of oligochaete worms (Enchytraeus albidus) and tested how survival was influenced by pre-exposure to 4-nonylphenol (4-NP), a common nonionic detergent found in sewage sludge amended soils. Results showed that combined effect of 4-NP and daily freeze-thaw cycles can cause higher mortality to worms as compared with sustained freezing or control temperature. Exposure to 4-NP caused a substantial depletion of glycogen reserves which is catabolized during freezing to produce cryoprotective concentrations of free glucose. Further, exposure to freeze-thaw cycles resulted in higher concentrations of 4-NP in worm tissues as compared to constant freezing or control temperature (2 °C). Thus, worms exposed to combined effect of freeze-thaw cycles and 4-NP suffer higher consequences, with the toxic effect of the chemical potentiating the deleterious effects of freezing and thawing.

  13. Freeze-tolerance of Trichinella muscle larvae in experimentally infected wild boars

    DEFF Research Database (Denmark)

    Lacour, Sandrine A.; Heckmann, Aurelie; Mace, Pauline

    2013-01-01

    Freeze-tolerance of encapsulated Trichinella muscle larvae (ML) is mainly determined by Trichinella species, but is also influenced by host species, the age of the infection and the storage time and temperature of the infected meat. Moreover, the freeze-tolerance of the encapsulated species appears...... to be correlated to the development of thick capsule walls which increases with age. An extended infection period and the muscle composition in some hosts (e.g. herbivores) may provide freeze-avoiding matrices due to high carbohydrate contents. The present experiment compares freeze-tolerance of Trichinella...... served as negative controls. All wild boars were sacrificed 24 wpi. Muscle samples of 70 g were stored at -21 degrees C for 19,30 and 56h, and for 1-8 weeks. Larvae were recovered by artificial digestion. Their mobilities were recorded using Saisam (R) image analysis software and their infectivities were...

  14. Acclimation increases freezing stress response of Arabidopsis thaliana at proteome level

    KAUST Repository

    Fanucchi, Francesca

    2012-06-01

    This study used 2DE to investigate how Arabidopsis thaliana modulates protein levels in response to freezing stress after sub-lethal exposure at - 10 °C, both in cold-acclimated and in non-acclimated plants. A map was implemented in which 62 spots, corresponding to 44 proteins, were identified. Twenty-two spots were modulated upon treatments, and the corresponding proteins proved to be related to photosynthesis, energy metabolism, and stress response. Proteins demonstrated differences between control and acclimation conditions. Most of the acclimation-responsive proteins were either not further modulated or they were down-modulated by freezing treatment, indicating that the levels reached during acclimation were sufficient to deal with freezing. Anabolic metabolism appeared to be down-regulated in favor of catabolic metabolism. Acclimated plants and plants submitted to freezing after acclimation showed greater reciprocal similarity in protein profiles than either showed when compared both to control plants and to plants frozen without acclimation. The response of non-acclimated plants was aimed at re-modulating photosynthetic apparatus activity, and at increasing the levels of proteins with antioxidant-, molecular chaperone-, or post-transcriptional regulative functions. These changes, even less effective than the acclimation strategy, might allow the injured plastids to minimize the production of non-useful metabolites and might counteract photosynthetic apparatus injuries. © 2012 Elsevier B.V. All rights reserved.

  15. The Effect of Abscisic Acid on the Freezing Tolerance of Callus Cultures of Lotus corniculatus L.

    Science.gov (United States)

    Keith, C N; McKersie, B D

    1986-03-01

    The effects of growth temperature (2 degrees C and 24 degrees C), abscisic acid (ABA) concentration, duration of exposure to ABA, and light were assessed for their ability to induce acclimation to freezing temperatures in callus cultures of Lotus corniculatus L. cv Leo, a perennial forage legume. The maximal expression of freezing tolerance was achieved on B(5) media containing 10(-5) molar ABA, at 24 degrees C for 7 or 14 days. Under these culture conditions, the freezing tolerance of the callus approximated that observed in field grown plants. In contrast, low temperatures (2 degrees C) induced only a limited degree of freezing tolerance in these cultures. Viability was assessed by tetrazolium reduction and by regrowth of the callus. The two assays often differed in their estimates of absolute freezing tolerance. Regression analysis of the temperature profile suggested that there may be two or more distinct populations of cells differing in freezing tolerance, which may have contributed to the variability between viability assays.

  16. Genomic Regions Associated with Tolerance to Freezing Stress and Snow Mold in Winter Wheat

    Directory of Open Access Journals (Sweden)

    Erika B. Kruse

    2017-03-01

    Full Text Available Plants grown through the winter are subject to selective pressures that vary with each year’s unique conditions, necessitating tolerance of numerous abiotic and biotic stress factors. The objective of this study was to identify molecular markers in winter wheat (Triticum aestivum L. associated with tolerance of two of these stresses, freezing temperatures and snow mold—a fungal disease complex active under snow cover. A population of 155 F2:5 recombinant inbred lines from a cross between soft white wheat cultivars “Finch” and “Eltan” was evaluated for snow mold tolerance in the field, and for freezing tolerance under controlled conditions. A total of 663 molecular markers was used to construct a genetic linkage map and identify marker-trait associations. One quantitative trait locus (QTL associated with both freezing and snow mold tolerance was identified on chromosome 5A. A second, distinct, QTL associated with freezing tolerance also was found on 5A, and a third on 4B. A second QTL associated with snow mold tolerance was identified on chromosome 6B. The QTL on 5A associated with both traits was closely linked with the Fr-A2 (Frost-Resistance A2 locus; its significant association with both traits may have resulted from pleiotropic effects, or from greater low temperature tolerance enabling the plants to better defend against snow mold pathogens. The QTL on 4B associated with freezing tolerance, and the QTL on 6B associated with snow mold tolerance have not been reported previously, and may be useful in the identification of sources of tolerance for these traits.

  17. Chloroplast RNA-Binding Protein RBD1 Promotes Chilling Tolerance through 23S rRNA Processing in Arabidopsis

    Science.gov (United States)

    Yang, Leiyun; Yang, Fen; Wang, Yi; Zhu, Jian-Kang; Hua, Jian

    2016-01-01

    Plants have varying abilities to tolerate chilling (low but not freezing temperatures), and it is largely unknown how plants such as Arabidopsis thaliana achieve chilling tolerance. Here, we describe a genome-wide screen for genes important for chilling tolerance by their putative knockout mutants in Arabidopsis thaliana. Out of 11,000 T-DNA insertion mutant lines representing half of the genome, 54 lines associated with disruption of 49 genes had a drastic chilling sensitive phenotype. Sixteen of these genes encode proteins with chloroplast localization, suggesting a critical role of chloroplast function in chilling tolerance. Study of one of these proteins RBD1 with an RNA binding domain further reveals the importance of chloroplast translation in chilling tolerance. RBD1 is expressed in the green tissues and is localized in the chloroplast nucleoid. It binds directly to 23S rRNA and the binding is stronger under chilling than at normal growth temperatures. The rbd1 mutants are defective in generating mature 23S rRNAs and deficient in chloroplast protein synthesis especially under chilling conditions. Together, our study identifies RBD1 as a regulator of 23S rRNA processing and reveals the importance of chloroplast function especially protein translation in chilling tolerance. PMID:27138552

  18. Freeze tolerance differs between two ecotypes of Paspalum vaginatum (Poaceae

    Directory of Open Access Journals (Sweden)

    Liliana Teresa Fabbri

    2016-03-01

    Full Text Available Morphological and physiological responses to freezing were evaluated in two ecotypes of the perennial turfgrass Paspalum vaginatum. Leaf extension rate, number of active meristems, leaf water potential and net photosynthesis were measured on plants of both a commercial cultivar, 'Sea Isle 2000', and a wild ecotype from the Flooding Pampa grasslands of Argentina. Plants were propagated by cloning, cultivated in pots, and examined during 18 consecutive days under two treatments: a non-frozen control treatment (15.5±7 ºC and a frozen treatment with two stages: Stage 1 with four hours of freezing stress for 10 nights (-5ºC, and Stage 2 with 12 hours of freezing stress for eight nights (five nights at -5ºC and three nights at -8ºC. After these treatments, plants were returned to the outside environment to evaluate shoot injury and post-freezing recovery. Leaf water potential, net photosynthesis and leaf extension rate were significantly higher in the wild ecotype than in the commercial cultivar. Meristem density was reduced after freezing in both ecotypes, but was more pronounced in the commercial cultivar (98.5% than in the wild ecotype (80%. Thus, the two ecotypes coming from different environments, exhibited different morphological and physiological responses to exposure to freezing temperatures.

  19. Population Structure, Genetic Variation, and Linkage Disequilibrium in Perennial Ryegrass Populations Divergently Selected for Freezing Tolerance.

    Science.gov (United States)

    Kovi, Mallikarjuna Rao; Fjellheim, Siri; Sandve, Simen R; Larsen, Arild; Rudi, Heidi; Asp, Torben; Kent, Matthew Peter; Rognli, Odd Arne

    2015-01-01

    Low temperature is one of the abiotic stresses seriously affecting the growth of perennial ryegrass (Lolium perenne L.), and freezing tolerance is a complex trait of major agronomical importance in northern and central Europe. Understanding the genetic control of freezing tolerance would aid in the development of cultivars of perennial ryegrass with improved adaptation to frost. The plant material investigated in this study was an experimental synthetic population derived from pair-crosses among five European perennial ryegrass genotypes, representing adaptations to a range of climatic conditions across Europe. A total number of 80 individuals (24 of High frost [HF]; 29 of Low frost [LF], and 27 of Unselected [US]) from the second generation of the two divergently selected populations and an unselected (US) control population were genotyped using 278 genome-wide SNPs derived from perennial ryegrass transcriptome sequences. Our studies investigated the genetic diversity among the three experimental populations by analysis of molecular variance and population structure, and determined that the HF and LF populations are very divergent after selection for freezing tolerance, whereas the HF and US populations are more similar. Linkage disequilibrium (LD) decay varied across the seven chromosomes and the conspicuous pattern of LD between the HF and LF population confirmed their divergence in freezing tolerance. Furthermore, two F st outlier methods; finite island model (fdist) by LOSITAN and hierarchical structure model using ARLEQUIN, both detected six loci under directional selection. These outlier loci are most probably linked to genes involved in freezing tolerance, cold adaptation, and abiotic stress. These six candidate loci under directional selection for freezing tolerance might be potential marker resources for breeding perennial ryegrass cultivars with improved freezing tolerance.

  20. Population structure, genetic variation and linkage disequilibrium in perennial ryegrass populations divergently selected for freezing tolerance

    Directory of Open Access Journals (Sweden)

    Mallikarjuna Rao eKovi

    2015-11-01

    Full Text Available Low temperature is one of the abiotic stresses seriously affecting the growth of perennial ryegrass (Lolium perenne L. Understanding the genetic control of freezing tolerance would aid in the development of cultivars of perennial ryegrass with improved adaptation to frost. A total number of 80 individuals (24 of High frost [HF]; 29 of Low frost [LF] and 27 of Unselected [US] from the second generation of the two divergently selected populations and an unselected control population were genotyped using 278 genome-wide SNPs derived from Lolium perenne L. transcriptome sequence. Our studies showed that the HF and LF populations are very divergent after selection for freezing tolerance, whereas the HF and US populations are more similar. Linkage disequilibrium (LD decay varied across the seven chromosomes and the conspicuous pattern of LD between the HF and LF population confirmed their divergence in freezing tolerance. Furthermore, two Fst outlier methods; finite island model (fdist by LOSITAN and hierarchical structure model using ARLEQUIN detected six loci under directional selection. These outlier loci are most probably linked to genes involved in freezing tolerance, cold adaptation and abiotic stress and might be the potential marker resources for breeding perennial ryegrass cultivars with improved freezing tolerance.

  1. The intrinsically disordered protein LEA7 from Arabidopsis thaliana protects the isolated enzyme lactate dehydrogenase and enzymes in a soluble leaf proteome during freezing and drying.

    Science.gov (United States)

    Popova, Antoaneta V; Rausch, Saskia; Hundertmark, Michaela; Gibon, Yves; Hincha, Dirk K

    2015-10-01

    The accumulation of Late Embryogenesis Abundant (LEA) proteins in plants is associated with tolerance against stresses such as freezing and desiccation. Two main functions have been attributed to LEA proteins: membrane stabilization and enzyme protection. We have hypothesized previously that LEA7 from Arabidopsis thaliana may stabilize membranes because it interacts with liposomes in the dry state. Here we show that LEA7, contrary to this expectation, did not stabilize liposomes during drying and rehydration. Instead, it partially preserved the activity of the enzyme lactate dehydrogenase (LDH) during drying and freezing. Fourier-transform infrared (FTIR) spectroscopy showed no evidence of aggregation of LDH in the dry or rehydrated state under conditions that lead to complete loss of activity. To approximate the complex influence of intracellular conditions on the protective effects of a LEA protein in a convenient in-vitro assay, we measured the activity of two Arabidopsis enzymes (glucose-6-P dehydrogenase and ADP-glucose pyrophosphorylase) in total soluble leaf protein extract (Arabidopsis soluble proteome, ASP) after drying and rehydration or freezing and thawing. LEA7 partially preserved the activity of both enzymes under these conditions, suggesting its role as an enzyme protectant in vivo. Further FTIR analyses indicated the partial reversibility of protein aggregation in the dry ASP during rehydration. Similarly, aggregation in the dry ASP was strongly reduced by LEA7. In addition, mixtures of LEA7 with sucrose or verbascose reduced aggregation more than the single additives, presumably through the effects of the protein on the H-bonding network of the sugar glasses.

  2. The interaction between freezing tolerance and phenology in temperate deciduous trees

    Directory of Open Access Journals (Sweden)

    Yann eVitasse

    2014-10-01

    Full Text Available Temperate climates are defined by a distinct temperature seasonality with large and often unpredictable weather during any of the four seasons. To thrive in such climates, trees have to withstand a cold winter and the stochastic occurrence of freeze events during any time of the year. The physiological mechanisms trees adopt to escape, avoid and tolerate freezing temperatures include a cold acclimation in autumn, a dormancy period during winter (leafless in deciduous trees, and the maintenance of a certain freezing tolerance during dehardening in early spring. The change from one phase to the next is mediated by complex interactions between temperature and photoperiod. This review aims at providing an overview of the interplay between phenology of leaves and species-specific freezing resistance. First, we address the long-term evolutionary responses that enabled temperate trees to tolerate certain low temperature extremes. We provide evidence that short term acclimation of freezing resistance plays a crucial role both in dormant and active buds, including re-acclimation to cold conditions following warm spells. This ability declines to almost zero during leaf emergence. Second, we show that the risk that native temperate trees encounter freeze injuries is low and is confined to spring and underline that this risk might be altered by climate warming depending on species-specific phenological responses to environmental cues.

  3. Re-Evaluation of Reportedly Metal Tolerant Arabidopsis thaliana Accessions

    Science.gov (United States)

    Silva-Guzman, Macarena; Addo-Quaye, Charles; Dilkes, Brian P.

    2016-01-01

    Santa Clara, Limeport, and Berkeley are Arabidopsis thaliana accessions previously identified as diversely metal resistant. Yet these same accessions were determined to be genetically indistinguishable from the metal sensitive Col-0. We robustly tested tolerance for Zn, Ni and Cu, and genetic relatedness by growing these accessions under a range of Ni, Zn and Cu concentrations for three durations in multiple replicates. Neither metal resistance nor variance in growth were detected between them and Col-0. We re-sequenced the genomes of these accessions and all stocks available for each accession. In all cases they were nearly indistinguishable from the standard laboratory accession Col-0. As Santa Clara was allegedly collected from the Jasper Ridge serpentine outcrop in California, USA we investigated the possibility of extant A. thaliana populations adapted to serpentine soils. Botanically vouchered Arabidopsis accessions in the Jepson database were overlaid with soil maps of California. This provided no evidence of A. thaliana collections from serpentine sites in California. Thus, our work demonstrates that the Santa Clara, Berkeley and Limeport accessions are not metal tolerant, not genetically distinct from Col-0, and that there are no known serpentine adapted populations or accessions of A. thaliana. PMID:27467746

  4. Activated Expression of WRKY57 Confers Drought Tolerance in Arabidopsis

    Institute of Scientific and Technical Information of China (English)

    Yanjuan Jiang; Gang Liang; Diqiu Yu

    2012-01-01

    Drought is one of the most serious environmental factors that limit the productivity of agricultural crops worldwide.However,the mechanism underlying drought tolerance in plants is unclear.WRKY transcription factors are known to function in adaptation to abiotic stresses.By screening a pool of WRKY-associated T-DNA insertion mutants,we isolated a gain-of-function mutant,acquired drought tolerance (adt),showing improved drought tolerance.Under drought stress conditions,adt accumulated higher levels of ABA than wild-type plants.Stomatal aperture analysis indicated that adt was more sensitive to ABA than wild-type plants.Molecular genetic analysis revealed that a T-DNA insertion in adt led to activated expression of a WRKY gene that encodes the WRKR57 protein.Constitutive expression of WRKY57 also conferred similar drought tolerance.Consistently with the high ABA content and enhanced drought tolerance,three stress-responsive genes (RD29A,NCED3,and ABA3) were up-regulated in adt.ChIP assays demonstrated that WRKY57 can directly bind the W-box of RD29A and NCED3 promoter sequences.In addition,during ABA treatment,seed germination and early seedling growth of adt were inhibited,whereas,under high osmotic conditions,adt showed a higher seed germination frequency.In summary,our results suggested that the activated expression of WRKY57 improved drought tolerance of Arabidopsis by elevation of ABA levels.Establishment of the functions of WRKY57 will enable improvement of plant drought tolerance through gene manipulation approaches.

  5. CO{sub 2} enrichment and development of freezing tolerance in Norway spruce

    Energy Technology Data Exchange (ETDEWEB)

    Dalen, L.S.; Johnsen, Oe.; Ogner, G. [Norwegian Forest Research Inst., Aas (Norway)

    2001-07-01

    Plant growth and adaptation to cold and freezing temperatures in a CO{sub 2}-enriched atmosphere have received little attention despite their predicted effects on plant distribution and productivity. In this study we looked at the interaction between elevated CO{sub 2} and development of freezing tolerance in Norway spruce (Picea abies (L.) Karst.). First-year seedlings were grown under controlled conditions in an atmosphere enriched in CO{sub 2} (70 Pa) for one simulated growth season. We measured shoot growth, registered the timing of growth cessation and bud set, measured needle net photosynthetic rate, and determined needle carbohydrate concentration (fructose + pinitol, glucose, sucrose, inositol, raffinose and starch). Freezing tolerance (LT{sub 50}) was determined after exposing whole seedlings to temperatures ranging from - 6.5 to - 36.0 deg. C and scoring for visual needle browning. Elevated CO{sub 2} did not affect height growth or the timing of growth cessation and bud set. The only statistically significant effects of CO2 treatment were on seedling dry weight, percent dry matter and starch content. During the three weeks after growth cessation and bud set, freezing tolerance increased from - 10 to - 35 deg. C, and there was a marked increase in all soluble sugars except inositol. However, neither freezing tolerance nor the concentration of soluble sugars was significantly influenced by elevated CO{sub 2}. (au)

  6. The PSE1 gene modulates lead tolerance in Arabidopsis

    Science.gov (United States)

    Fan, Tingting; Yang, Libo; Wu, Xi; Ni, Jiaojiao; Jiang, Haikun; Zhang, Qi’an; Fang, Ling; Sheng, Yibao; Ren, Yongbing; Cao, Shuqing

    2016-01-01

    Lead (Pb) is a dangerous heavy metal contaminant with high toxicity to plants. However, the regulatory mechanism of plant Pb tolerance is poorly understood. Here, we showed that the PSE1 gene confers Pb tolerance in Arabidopsis. A novel Pb-sensitive mutant pse1-1 (Pb-sensitive1) was isolated by screening T-DNA insertion mutants. PSE1 encodes an unknown protein with an NC domain and was localized in the cytoplasm. PSE1 was induced by Pb stress, and the pse1-1 loss-of-function mutant showed enhanced Pb sensitivity; overexpression of PSE1 resulted in increased Pb tolerance. PSE1-overexpressing plants showed increased Pb accumulation, which was accompanied by the activation of phytochelatin (PC) synthesis and related gene expression. In contrast, the pse1-1 mutant showed reduced Pb accumulation, which was associated with decreased PC synthesis and related gene expression. In addition, the expression of PDR12 was also increased in PSE1-overexpressing plants subjected to Pb stress. Our results suggest that PSE1 regulates Pb tolerance mainly through glutathione-dependent PC synthesis by activating the expression of the genes involved in PC synthesis and at least partially through activating the expression of the ABC transporter PDR12/ABCG40. PMID:27335453

  7. Cryoprotectants and extreme freeze tolerance in a subarctic population of the wood frog.

    Directory of Open Access Journals (Sweden)

    Jon P Costanzo

    Full Text Available Wood frogs (Rana sylvatica exhibit marked geographic variation in freeze tolerance, with subarctic populations tolerating experimental freezing to temperatures at least 10-13 degrees Celsius below the lethal limits for conspecifics from more temperate locales. We determined how seasonal responses enhance the cryoprotectant system in these northern frogs, and also investigated their physiological responses to somatic freezing at extreme temperatures. Alaskan frogs collected in late summer had plasma urea levels near 10 μmol ml-1, but this level rose during preparation for winter to 85.5 ± 2.9 μmol ml-1 (mean ± SEM in frogs that remained fully hydrated, and to 186.9 ± 12.4 μmol ml-1 in frogs held under a restricted moisture regime. An osmolality gap indicated that the plasma of winter-conditioned frogs contained an as yet unidentified osmolyte(s that contributed about 75 mOsmol kg-1 to total osmotic pressure. Experimental freezing to -8°C, either directly or following three cycles of freezing/thawing between -4 and 0°C, or -16°C increased the liver's synthesis of glucose and, to a lesser extent, urea. Concomitantly, organs shed up to one-half (skeletal muscle or two-thirds (liver of their water, with cryoprotectant in the remaining fluid reaching concentrations as high as 0.2 and 2.1 M, respectively. Freeze/thaw cycling, which was readily survived by winter-conditioned frogs, greatly increased hepatic glycogenolysis and delivery of glucose (but not urea to skeletal muscle. We conclude that cryoprotectant accrual in anticipation of and in response to freezing have been greatly enhanced and contribute to extreme freeze tolerance in northern R. sylvatica.

  8. Cryoprotectants and extreme freeze tolerance in a subarctic population of the wood frog.

    Science.gov (United States)

    Costanzo, Jon P; Reynolds, Alice M; do Amaral, M Clara F; Rosendale, Andrew J; Lee, Richard E

    2015-01-01

    Wood frogs (Rana sylvatica) exhibit marked geographic variation in freeze tolerance, with subarctic populations tolerating experimental freezing to temperatures at least 10-13 degrees Celsius below the lethal limits for conspecifics from more temperate locales. We determined how seasonal responses enhance the cryoprotectant system in these northern frogs, and also investigated their physiological responses to somatic freezing at extreme temperatures. Alaskan frogs collected in late summer had plasma urea levels near 10 μmol ml-1, but this level rose during preparation for winter to 85.5 ± 2.9 μmol ml-1 (mean ± SEM) in frogs that remained fully hydrated, and to 186.9 ± 12.4 μmol ml-1 in frogs held under a restricted moisture regime. An osmolality gap indicated that the plasma of winter-conditioned frogs contained an as yet unidentified osmolyte(s) that contributed about 75 mOsmol kg-1 to total osmotic pressure. Experimental freezing to -8°C, either directly or following three cycles of freezing/thawing between -4 and 0°C, or -16°C increased the liver's synthesis of glucose and, to a lesser extent, urea. Concomitantly, organs shed up to one-half (skeletal muscle) or two-thirds (liver) of their water, with cryoprotectant in the remaining fluid reaching concentrations as high as 0.2 and 2.1 M, respectively. Freeze/thaw cycling, which was readily survived by winter-conditioned frogs, greatly increased hepatic glycogenolysis and delivery of glucose (but not urea) to skeletal muscle. We conclude that cryoprotectant accrual in anticipation of and in response to freezing have been greatly enhanced and contribute to extreme freeze tolerance in northern R. sylvatica.

  9. Recrystallization in a Freezing Tolerant Antarctic Nematode, Panagrolaimus davidi, and a Alpine Weta, Hemideina maori (Orthoptera; Stenopelmatidae)

    DEFF Research Database (Denmark)

    Ramløv, Hans; Wharton, David A.; Wilson, Peter W.

    1996-01-01

    The ability of haemolymph from the freezing tolerant weta,Hemideina maori,and supernatant from homogenates of the freezing tolerant nematodePanagrolaimus davidito inhibit the recrystallization of ice was examined using the “splat freezing” technique and annealing on a cryomicroscope stage. There ...

  10. Dual roles of glucose in the freeze-tolerant earthworm Dendrobaena octaedra: cryoprotection and fuel for metabolism

    DEFF Research Database (Denmark)

    Calderon, Sofia; Holmstrup, Martin; Westh, Peter;

    2009-01-01

    Ectothermic animals inhabiting the subarctic and temperate regions have evolved strategies to deal with periods of continuous frost during winter. The earthworm Dendrobaena octaedra is freeze tolerant and accumulates large concentrations of glucose upon freezing. The present study investigates...... degrees C of the 'average' D. octaedra. Such conditions are very likely to occur in the northern distribution ranges of this stress-tolerant earthworm....

  11. Cold acclimation induced accumulation of phenolic compounds and freezing tolerance in Ammopiptanthus mongolicus

    Institute of Scientific and Technical Information of China (English)

    Liu Mei-qin; Chen Yi-yin; Lu Cun-fu; Zhang Hui; Yin Wei-lun

    2007-01-01

    Ammopiptanthus mongolicus, the only freezing tolerant evergreen broad-leaved shrub, local species of the Alashan desert,northwest sand area of China, can survive -30℃ or even lower temperature in winter. In the present study, the secondary products phenolics in A. mongolicus cotyledons were determined to study the effects ofphenolics on cold tolerance. Cytochemical localization of phenolics in cotyledon cells was observed by electron microscopy and the content of phenolic compounds was assayed by spectrophotometric measurement. The results showed that the freezing tolerance of A. mongolicus seedlings increased after acclimation at 2-6℃ for 14 days, which accompanied the increase of the content of phenolic compounds in cotyledons. Cytochemical observation showed that phenolic deposits were mainly localized in vacuoles and in close proximity to tonoplast, and also in the cytoplasm. The amount and the size of phenolics droplets increased obviously in cytoplasm and vacuoles after cold acclimation, predominantly aggregated along membranes of vacuoles and tonoplast. No phenolic deposits were found in cell walls. As hydrogen- or electron-donating agents, phenolics may protect plant cells against reactive oxygen species formed during chilling or freezing stress and improve the freezing tolerance of cold-acclimated A. mongolicus seedlings.

  12. Physiological and molecular characterization of lucerne (Medicago sativa L.) germplasm with improved seedling freezing tolerance

    Science.gov (United States)

    We conducted greenhouse experiments to compare 14 alfalfa germplasms for their survival following freezing. Among these germplasms are collections adapted to the Grand River National Grasslands in South Dakota. Our hypothesis was that these collections developed tolerance to survive the frigid gro...

  13. Farinose flavonoids are associated with high freezing tolerance in fairy primrose (Primula malacoides) plants.

    Science.gov (United States)

    Isshiki, Ryutaro; Galis, Ivan; Tanakamaru, Shigemi

    2014-02-01

    The deposition of surface (farinose) flavonoids on aerial parts of some Primula species is a well-documented but poorly understood phenomenon. Here, we show that flavonoid deposition on the leaves and winter buds may contribute strongly to preventing freezing damage in these plants. The ice nucleation temperature of fairy primrose (Primula malacoides) leaves covered with natural flavone was approximately 6 °C lower compared to those that had their flavone artificially removed. Additionally, farinose flavonoids on the leaves reduced subsequent electrolyte leakage (EL) from the cells exposed to freezing temperatures. Interestingly, exogenous application of flavone at 4 mg/g fresh weight to P. malacoides leaves, which had the original flavone mechanically removed, restored freezing tolerance, and diminished EL from the cells to pretreatment values. Our results suggest that farinose flavonoids may function as mediators of freezing tolerance in P. malacoides, and exogenous application of flavone could be used to reduce freezing damage during sudden but predictable frost events in other plant species.

  14. Transcriptome Sequencing Identified Genes and Gene Ontologies Associated with Early Freezing Tolerance in Maize

    Science.gov (United States)

    Li, Zhao; Hu, Guanghui; Liu, Xiangfeng; Zhou, Yao; Li, Yu; Zhang, Xu; Yuan, Xiaohui; Zhang, Qian; Yang, Deguang; Wang, Tianyu; Zhang, Zhiwu

    2016-01-01

    Originating in a tropical climate, maize has faced great challenges as cultivation has expanded to the majority of the world's temperate zones. In these zones, frost and cold temperatures are major factors that prevent maize from reaching its full yield potential. Among 30 elite maize inbred lines adapted to northern China, we identified two lines of extreme, but opposite, freezing tolerance levels—highly tolerant and highly sensitive. During the seedling stage of these two lines, we used RNA-seq to measure changes in maize whole genome transcriptome before and after freezing treatment. In total, 19,794 genes were expressed, of which 4550 exhibited differential expression due to either treatment (before or after freezing) or line type (tolerant or sensitive). Of the 4550 differently expressed genes, 948 exhibited differential expression due to treatment within line or lines under freezing condition. Analysis of gene ontology found that these 948 genes were significantly enriched for binding functions (DNA binding, ATP binding, and metal ion binding), protein kinase activity, and peptidase activity. Based on their enrichment, literature support, and significant levels of differential expression, 30 of these 948 genes were selected for quantitative real-time PCR (qRT-PCR) validation. The validation confirmed our RNA-Seq-based findings, with squared correlation coefficients of 80% and 50% in the tolerance and sensitive lines, respectively. This study provided valuable resources for further studies to enhance understanding of the molecular mechanisms underlying maize early freezing response and enable targeted breeding strategies for developing varieties with superior frost resistance to achieve yield potential. PMID:27774095

  15. The Alfin-like homeodomain finger protein AL5 suppresses multiple negative factors to confer abiotic stress tolerance in Arabidopsis.

    Science.gov (United States)

    Wei, Wei; Zhang, Yu-Qin; Tao, Jian-Jun; Chen, Hao-Wei; Li, Qing-Tian; Zhang, Wan-Ke; Ma, Biao; Lin, Qing; Zhang, Jin-Song; Chen, Shou-Yi

    2015-03-01

    Plant homeodomain (PHD) finger proteins affect processes of growth and development by changing transcription and reading epigenetic histone modifications, but their functions in abiotic stress responses remain largely unclear. Here we characterized seven Arabidopsis thaliana Alfin1-like PHD finger proteins (ALs) in terms of the responses to abiotic stresses. ALs localized to the nucleus and repressed transcription. Except AL6, all the ALs bound to G-rich elements. Mutations of the amino acids at positions 34 and 35 in AL6 caused loss of ability to bind to G-rich elements. Expression of the AL genes responded differentially to osmotic stress, salt, cold and abscisic acid treatments. AL5-over-expressing plants showed higher tolerance to salt, drought and freezing stress than Col-0. Consistently, al5 mutants showed reduced stress tolerance. We used ChIP-Seq assays to identify eight direct targets of AL5, and found that AL5 binds to the promoter regions of these genes. Knockout mutants of five of these target genes exhibited varying tolerances to stresses. These results indicate that AL5 inhibits multiple signaling pathways to confer stress tolerance. Our study sheds light on mechanisms of AL5-mediated signaling in abiotic stress responses, and provides tools for improvement of stress tolerance in crop plants.

  16. Freeze-tolerance of Trichinella muscle larvae in experimentally infected wild boars.

    Science.gov (United States)

    Lacour, Sandrine A; Heckmann, Aurélie; Macé, Pauline; Grasset-Chevillot, Aurélie; Zanella, Gina; Vallée, Isabelle; Kapel, Christian M O; Boireau, Pascal

    2013-05-20

    Freeze-tolerance of encapsulated Trichinella muscle larvae (ML) is mainly determined by Trichinella species, but is also influenced by host species, the age of the infection and the storage time and temperature of the infected meat. Moreover, the freeze-tolerance of the encapsulated species appears to be correlated to the development of thick capsule walls which increases with age. An extended infection period and the muscle composition in some hosts (e.g. herbivores) may provide freeze-avoiding matrices due to high carbohydrate contents. The present experiment compares freeze-tolerance of Trichinella spiralis and Trichinella britovi ML in wild boar meat 24 weeks post inoculation (wpi). Three groups of four wild boars were infected with 200, 2000 or 20,000 ML of T. britovi (ISS 1575), respectively. Additionally, three wild boars were inoculated with 20,000 ML of T. spiralis (ISS 004) and two animals served as negative controls. All wild boars were sacrificed 24 wpi. Muscle samples of 70 g were stored at -21°C for 19, 30 and 56 h, and for 1-8 weeks. Larvae were recovered by artificial digestion. Their mobilities were recorded using Saisam(®) image analysis software and their infectivities were evaluated using mouse bioassays. Samples frozen for 19, 30 and 56 h allowed recovery of mobile ML, but samples frozen for 1 or 2 weeks did not. Correspondingly, only T. spiralis and T. britovi larvae isolated from wild boar meat frozen for 19, 30 and 56 h established in mice. This study showed that freezing at -21°C for 1 week inactivated T. spiralis and T. britovi ML encapsulated in wild boar meat for 24 weeks.

  17. Freezing tolerance revisited-effects of variable temperatures on gene regulation in temperate grasses and legumes.

    Science.gov (United States)

    Kovi, Mallikarjuna Rao; Ergon, Åshild; Rognli, Odd Arne

    2016-10-01

    Climate change creates new patterns of seasonal climate variation with higher temperatures, longer growth seasons and more variable winter climates. This is challenging the winter survival of perennial herbaceous plants. In this review, we focus on the effects of variable temperatures during autumn/winter/spring, and its interactions with light, on the development and maintenance of freezing tolerance. Cold temperatures induce changes at several organizational levels in the plant (cold acclimation), leading to the development of freezing tolerance, which can be reduced/lost during warm spells (deacclimation) in winters, and attained again during cold spells (reacclimation). We summarize how temperature interacts with components of the light regime (photoperiod, PSII excitation pressure, irradiance, and light quality) in determining changes in the transcriptome, proteome and metabolome.

  18. Drought increases freezing tolerance of both leaves and xylem of Larrea tridentata.

    Science.gov (United States)

    Medeiros, Juliana S; Pockman, William T

    2011-01-01

    Drought and freezing are both known to limit desert plant distributions, but the interaction of these stressors is poorly understood. Drought may increase freezing tolerance in leaves while decreasing it in the xylem, potentially creating a mismatch between water supply and demand. To test this hypothesis, we subjected Larrea tridentata juveniles grown in a greenhouse under well-watered or drought conditions to minimum temperatures ranging from -8 to -24 °C. We measured survival, leaf retention, gas exchange, cell death, freezing point depression and leaf-specific xylem hydraulic conductance (k₁). Drought-exposed plants exhibited smaller decreases in gas exchange after exposure to -8 °C compared to well-watered plants. Drought also conferred a significant positive effect on leaf, xylem and whole-plant function following exposure to -15 °C; drought-exposed plants exhibited less cell death, greater leaf retention, higher k₁ and higher rates of gas exchange than well-watered plants. Both drought-exposed and well-watered plants experienced 100% mortality following exposure to -24 °C. By documenting the combined effects of drought and freezing stress, our data provide insight into the mechanisms determining plant survival and performance following freezing and the potential for shifts in L. tridentata abundance and range in the face of changing temperature and precipitation regimes.

  19. SRAP polymorphisms associated with superior freezing tolerance in alfalfa (Medicago sativa spp. sativa).

    Science.gov (United States)

    Castonguay, Yves; Cloutier, Jean; Bertrand, Annick; Michaud, Réal; Laberge, Serge

    2010-05-01

    Sequence-related amplified polymorphism (SRAP) analysis was used to uncover genetic polymorphisms among alfalfa populations recurrently selected for superior tolerance to freezing (TF populations). Bulk DNA samples (45 plants/bulk) from each of the cultivar Apica (ATF0), and populations ATF2, ATF4, ATF5, and ATF6 were evaluated with 42 different SRAP primer pairs. Several polymorphisms that progressively intensified or decreased with the number of recurrent cycles were identified. Four positive polymorphisms (F10-R14, Me4-R8, F10-R8 and F11-R9) that, respectively, yielded 540-, 359-, 213-, and 180-bp fragments were selected for further analysis. SRAP amplifications with genotypes within ATF populations confirmed that the polymorphisms identified with bulk DNA samples were reflecting changes in the frequency of their occurrence in response to selection. In addition, the number of genotypes cumulating multiple polymorphisms markedly increased in response to recurrent selection. Independent segregation of the four SRAP polymorphisms suggests location at unlinked loci. Homology search gave matches with BAC clones from syntenic Medicago truncatula for the four SRAP fragments. Analysis of the relationship with low temperature tolerance showed that multiple SRAP polymorphisms are more frequent in genotypes that maintain superior regrowth after freezing. These results show that SRAP analysis of bulk DNA samples from recurrent selections is an effective approach for the identification of genetic polymorphisms associated with quantitative traits in allogamous species. These polymorphisms could be useful tools for indirect selection of freezing tolerance in alfalfa.

  20. Ice recrystallization inhibition proteins (IRIPs) and freeze tolerance in the cryophilic Antarctic hair grass Deschampsia antarctica E. Desv.

    Science.gov (United States)

    John, Ulrik P; Polotnianka, Renatam M; Sivakumaran, Kailayapillai A; Chew, Orinda; Mackin, Leanne; Kuiper, Micheal J; Talbot, Jonathan P; Nugent, Gregory D; Mautord, Julie; Schrauf, Gustavo E; Spangenberg, German C

    2009-04-01

    Antarctic hair grass (Deschampsia antarctica E. Desv.), the only grass indigenous to Antarctica, has well-developed freezing tolerance, strongly induced by cold acclimation. Here, we show that in response to low temperatures, D. antarctica expresses potent recrystallization inhibition (RI) activity that, inhibits the growth of small ice crystals into potentially damaging large ones, is proteinaceous and localized to the apoplasm. A gene family from D. antarctica encoding putative homologs of an ice recrystallization inhibition protein (IRIP) has been isolated and characterized. IRIPs are apoplastically targeted proteins with two potential ice-binding motifs: 1-9 leucine-rich repeats (LRRs) and c. 16 'IRIP' repeats. IRIP genes appear to be confined to the grass subfamily Pooideae and their products, exhibit sequence similarity to phytosulphokine receptors and are predicted to adopt conformations with two ice-binding surfaces. D. antarctica IRIP (DaIRIP) transcript levels are greatly enhanced in leaf tissue following cold acclimation. Transgenic Arabidopsis thaliana expressing a DaIRIP has novel RI activity, and purified DaIRIP, when added back to extracts of leaves from non-acclimated D. antarctica, can reconstitute the activity found in acclimated plants. We propose that IRIP-mediated RI activity may contribute to the cryotolerance of D. antarctica, and thus to its unique ability to have colonized Antarctica.

  1. Exogenous Abscisic Acid Mimics Cold Acclimation for Cacti Differing in Freezing Tolerance.

    Science.gov (United States)

    Loik, M. E.; Nobel, P. S.

    1993-11-01

    The responses to low temperature were determined for two species of cacti sensitive to freezing, Ferocactus viridescens and Opuntia ficus-indica, and a cold hardy species, Opuntia fragilis. Fourteen days after shifting the plants from day/night air temperatures of 30/20[deg]C to 10/0[deg]C, the chlorenchyma water content decreased only for O. fragilis. This temperature shift caused the freezing tolerance (measured by vital stain uptake) of chlorenchyma cells to be enhanced only by about 2.0[deg]C for F. viridescens and O. ficus-indica but by 14.6[deg]C for O. fragilis. Also, maintenance of high water content by injection of water into plants at 10/0[deg]C reversed the acclimation. The endogenous abscisic acid (ABA) concentration was below 0.4 pmol g-1 fresh weight at 30/20[deg]C, but after 14 d at 10/0[deg]C it increased to 84 pmol g-1 fresh weight for O. ficus-indica and to 49 pmol g-1 fresh weight for O. fragilis. Four days after plants were sprayed with 7.5 x 10-5 M ABA at 30/20[deg]C, freezing tolerance was enhanced by 0.5[deg]C for F. viridescens, 4.1[deg]C for O. ficus-indica, and 23.4[deg]C for O. fragilis. Moreover, the time course for the change in freezing tolerance over 14 d was similar for plants shifted to low temperatures as for plants treated with exogenous ABA at moderate temperatures. Decreases in plant water content and increases in ABA concentration may be important for low-temperature acclimation by cacti, especially O. fragilis, which is widely distributed in Canada and the United States.

  2. Anthocyanin biosynthesis for cold and freezing stress tolerance and desirable color in Brassica rapa.

    Science.gov (United States)

    Ahmed, Nasar Uddin; Park, Jong-In; Jung, Hee-Jeong; Hur, Yoonkang; Nou, Ill-Sup

    2015-07-01

    Flavonoids are divided into several structural classes, including anthocyanins, which provide flower and leaf colors and other derivatives that play diverse roles in plant development and interactions with the environment. This study characterized four anthocyanidin synthase (ANS) genes of Brassica rapa, a structural gene of the anthocyanin biosynthetic pathway, and investigated their association with pigment formation, cold and freezing tolerance in B. rapa. Sequences of these genes were analyzed and compared with similar gene sequences from other species, and a high degree of homology with their respective functions was found. Organ-specific expression analysis revealed that these genes were only expressed in the colored portion of leaves of different lines of B. rapa. Conversely, B. rapa anthocyanidin synthase (BrANS) genes also showed responses to cold and freezing stress treatment in B. rapa. BrANSs were also shown to be regulated by two transcription factors, BrMYB2-2 and BrTT8, contrasting with anthocyanin accumulation and cold stress. Thus, the above results suggest the association of these genes with anthocyanin biosynthesis and cold and freezing stress tolerance and might be useful resources for development of cold-resistant Brassica crops with desirable colors as well.

  3. Effects of a freezing event during hibernation on further survival, reproduction and growth in the partially freezing tolerant land snail Helix aspersa muller (Gastropoda: helicidae).

    Science.gov (United States)

    Ansart, Armelle; Vernon, Philippe; Daguzan, Jacques

    2002-01-01

    Tolerance of ectothermic animals to freezing is often estimated by assessing survival a few days after the treatment. However, in the long term, ice formation in the body tissues can affect survival, as well as reproductive capability and growth. The land snail Helix aspersa survives only short durations with ice in its tissues, to a lethal limit of 40 to 60 % of its body water frozen. Adult and immature snails were treated during their winter dormancy period to a freezing event above this limit; their survival was observed both in the short and long term, as well as their ability to reproduce (adults) and grow (immature snails). Treated snails were compared with a control group, which was not frozen. No difference appeared in the survival, reproduction and growth of control and frozen snails. This study confirms partial freezing tolerance in this population of Helix aspersa.

  4. Ice-Active Substances from the Infective Juveniles of the Freeze Tolerant Entomopathogenic Nematode, Steinernema feltiae.

    Directory of Open Access Journals (Sweden)

    Farman Ali

    Full Text Available Steinernema feltiae is a moderately freezing tolerant nematode, that can withstand intracellular ice formation. We investigated recrystallization inhibition, thermal hysteresis and ice nucleation activities in the infective juveniles of S. feltiae. Both the splat cooling assay and optical recrystallometry indicate the presence of ice active substances that inhibit recrystallization in the nematode extract. The substance is relatively heat stable and largely retains the recrystallization inhibition activity after heating. No thermal hysteresis activity was detected but the extract had a typical hexagonal crystal shape when grown from a single seed crystal and weak ice nucleation activity. An ice active substance is present in a low concentration, which may be involved in the freezing survival of this species by inhibiting ice recrystallization.

  5. Metabolic mechanisms for anoxia tolerance and freezing survival in the intertidal gastropod, Littorina littorea.

    Science.gov (United States)

    Storey, Kenneth B; Lant, Benjamin; Anozie, Obiajulu O; Storey, Janet M

    2013-08-01

    The gastropod mollusk, Littorina littorea L., is a common inhabitant of the intertidal zone along rocky coastlines of the north Atlantic. This species has well-developed anoxia tolerance and freeze tolerance and is extensively used as a model for exploring the biochemical adaptations that support these tolerances as well as for toxicological studies aimed at identifying effective biomarkers of aquatic pollution. This article highlights our current understanding of the molecular mechanisms involved in anaerobiosis and freezing survival of periwinkles, particularly with respect to anoxia-induced metabolic rate depression. Analysis of foot muscle and hepatopancreas metabolism includes anoxia-responsive changes in enzyme regulation, signal transduction, gene expression, post-transcriptional regulation of mRNA, control of translation, and cytoprotective strategies including chaperones and antioxidant defenses. New studies describe the regulation of glucose-6-phosphate dehydrogenase by reversible protein phosphorylation, the role of microRNAs in suppressing mRNA translation in the hypometabolic state, modulation of glutathione S-transferase isozyme patterns, and the regulation of the unfolded protein response.

  6. Evaluation of Freezing Tolerance of Three Ajowan (Trachyspermum ammi (Linn. Sprague Ecotypes in Controlled Conditions

    Directory of Open Access Journals (Sweden)

    Z Boroumand Rezazadeh

    2013-08-01

    Full Text Available Ajowan is one of the endemic plants in Khorasan province, and there is a little information on its tolerance to cold stress. In order to study freezing tolerance of ajowan, an experiment was conducted in faculty of agriculture, Ferdowsi University of Mashhad, based on factorial-completely randomized design with three replications and three ecotypes of ajowan (Neishabour, Birjand and Torbat-e-Heidarieh were imposed on eight freezing temperatures (0 (control, -1.5, -3, -4.5, -6,-7.5, -9 and -10.5 °C. Plants were grown in natural environment till 4-5 leaf stage, then for freezing treatments transferred to thermo-gradient freezer. The cell membrane stability was evaluated by electrolyte leakage index (EL and temperature for killing 50% of samples according to the electrolyte leakage (LT50el was determined. Furthermore, survival percentage, leaf number and dry weight, temperature for killing 50% of samples according to survival (LT50su and reduced dry matter temperature 50 (RDMT50 were determined after three weeks recovery in the glasshouse. Response of ajowan ecotypes for electrolyte leakage was different and birjand ecotype had the lowest %EL, whereas the slope of %EL in mentioned ecotype was lower than two other ecotypes. However there were no significant differences among ajowan ecotypes on LT50su. Decreasing temperature to -7.5 °C reduced survival percentage of Neishabour and Torbat-e-Heidarieh ecotypes to lower than 20 percent, whiles in this temperature Birjand’s survival percentage was about 60 percent. It seems that Birjand ecotype with the lowest electrolyte leakage, the highest survival and dry matter and the lowest LT50su was more tolerant than two other ecotypes.

  7. Evaluation of Freeze Tolerance in Lancelot Plantain (Plantago lanceolata L. Ecotypes under Controlled Conditions

    Directory of Open Access Journals (Sweden)

    M. Janalizadeh

    2016-02-01

    Full Text Available Introduction Lancelot Plantain (Ribwort, narrow-leaf or English plantain is a deep-rooted, short-lived perennial herb from Plantaginaceae family which has been used for various medicinal purposes for centuries, especially in Europe and only more recently has been proposed as a forage plant. The leaf of plantain is highly palatable for grazing animals, providing mineral-rich forage. Recently two productive upright cultivars of plantain have been bred and introduced, Grasslands Lancelot and the more erect winter active Ceres Tonic. Plantain grows moderately in winter but its main growth periods beings in spring and autumn with opportunistic summer growth. Although it reveals suitable winter survival in natural conditions, but there is not a lot of information about cold tolerance of this plant. So it is important to recognize the freeze tolerance of narrow leaf plantain for successful planting and utilization in cold regions such as Mashhad in Khorasan Razavi Province (Northeast of Iran. Determining LT50 point or critical temperature for survival of plant is the most reliable and simple method for evaluating cold tolerance of plants. Another reliable method for freeze tolerance of plants is estimation of temperature at which 50 % of dry matter reduces (RDMT50. This experiment was carried out to evaluate freeze tolerance of five ecotypes of Lancelot plantain according to the LT50su and RDMT50 indices. Materials and Methods In order to evaluate freeze tolerance of Lancelot plantain, a factorial experiment based on completely randomized design with three replications was carried out under controlled conditions at college of agriculture, Ferdowsi University of Mashhad. Five ecotypes of Lancelot plantain (Bojnourd, Kalat, Mashhad, Ghayen and Birjand after three months growth and hardening in natural environment were transferred to a Thermo gradient freezer on January 20th, 2012 and exposed to eight freezing temperatures (Zero, -3, -6, -9, -12, -15, -18

  8. Seasonal Variation in the Hepatoproteome of the Dehydration- and Freeze-Tolerant Wood Frog, Rana sylvatica

    Directory of Open Access Journals (Sweden)

    Jon P. Costanzo

    2011-11-01

    Full Text Available Winter’s advent invokes physiological adjustments that permit temperate ectotherms to cope with stresses such as food shortage, water deprivation, hypoxia, and hypothermia. We used liquid chromatography (LC in combination with tandem mass spectrometry (MS/MS quantitative isobaric (iTRAQ™ peptide mapping to assess variation in the abundance of hepatic proteins in summer- and winter-acclimatized wood frogs (Rana sylvatica, a northerly-distributed species that tolerates extreme dehydration and tissue freezing during hibernation. Thirty-three unique proteins exhibited strong seasonal lability. Livers of winter frogs had relatively high levels of proteins involved in cytoprotection, including heat-shock proteins and an antioxidant, and a reduced abundance of proteins involved in cell proliferation, protein synthesis, and mitochondrial function. They also exhibited altered levels of certain metabolic enzymes that participate in the biochemical reorganization associated with aphagia and reliance on energy reserves, as well as the freezing mobilization and post-thaw recovery of glucose, an important cryoprotective solute in freezing adaptation.

  9. Fluidization of membrane lipids enhances the tolerance of Saccharomyces cerevisiae to freezing and salt stress.

    Science.gov (United States)

    Rodríguez-Vargas, Sonia; Sánchez-García, Alicia; Martínez-Rivas, Jose Manuel; Prieto, Jose Antonio; Randez-Gil, Francisca

    2007-01-01

    Unsaturated fatty acids play an essential role in the biophysical characteristics of cell membranes and determine the proper function of membrane-attached proteins. Thus, the ability of cells to alter the degree of unsaturation in their membranes is an important factor in cellular acclimatization to environmental conditions. Many eukaryotic organisms can synthesize dienoic fatty acids, but Saccharomyces cerevisiae can introduce only a single double bond at the Delta(9) position. We expressed two sunflower (Helianthus annuus) oleate Delta(12) desaturases encoded by FAD2-1 and FAD2-3 in yeast cells of the wild-type W303-1A strain (trp1) and analyzed their effects on growth and stress tolerance. Production of the heterologous desaturases increased the content of dienoic fatty acids, especially 18:2Delta(9,12), the unsaturation index, and the fluidity of the yeast membrane. The total fatty acid content remained constant, and the level of monounsaturated fatty acids decreased. Growth at 15 degrees C was reduced in the FAD2 strains, probably due to tryptophan auxotrophy, since the trp1 (TRP1) transformants that produced the sunflower desaturases grew as well as the control strain did. Our results suggest that changes in the fluidity of the lipid bilayer affect tryptophan uptake and/or the correct targeting of tryptophan transporters. The expression of the sunflower desaturases, in either Trp(+) or Trp(-) strains, increased NaCl tolerance. Production of dienoic fatty acids increased the tolerance to freezing of wild-type cells preincubated at 30 degrees C or 15 degrees C. Thus, membrane fluidity is an essential determinant of stress resistance in S. cerevisiae, and engineering of membrane lipids has the potential to be a useful tool of increasing the tolerance to freezing in industrial strains.

  10. Silencing of TaBTF3 gene impairs tolerance to freezing and drought stresses in wheat.

    Science.gov (United States)

    Kang, Guozhang; Ma, Hongzhen; Liu, Guoqin; Han, Qiaoxia; Li, Chengwei; Guo, Tiancai

    2013-11-01

    Basic transcription factor 3 (BTF3), the β-subunit of the nascent polypeptide-associated complex, is responsible for the transcriptional initiation of RNA polymerase II and is also involved in cell apoptosis, translation initiation regulation, growth, development, and other functions. Here, we report the impact of BTF3 on abiotic tolerance in higher plants. The transcription levels of the TaBTF3 gene, first isolated from wheat seedlings in our lab, were differentially regulated by diverse abiotic stresses and hormone treatments, including PEG-induced stress (20 % polyethylene glycol 6000), cold (4 °C), salt (100 mM NaCl), abscisic acid (100 μM), methyl jasmonate (50 μM), and salicylic acid (50 μM). Southern blot analysis indicated that, in the wheat genome, TaBTF3 is a multi-copy gene. Compared to BSMV-GFP-infected wheat plants (control), under freezing (-8 °C for 48 h) or drought stress (withholding water for 15 days) conditions, TaBTF3-silenced wheat plants showed lower survival rates, free proline content, and relative water content and higher relative electrical conductivity and water loss rate. These results suggest that silencing of the TaBTF3 gene may impair tolerance to freezing and drought stresses in wheat and that it may be involved in the response to abiotic stresses in higher plants.

  11. Water Relations and Low-Temperature Acclimation for Cactus Species Varying in Freezing Tolerance.

    Science.gov (United States)

    Goldstein, G.; Nobel, P. S.

    1994-02-01

    Opuntia ficus-indica and Opuntia streptacantha are widely cultivated cacti that can tolerate temperatures no lower than -10[deg]C, whereas Opuntia humifusa, which is native to southern Canada and the eastern United States, can tolerate -24[deg]C. As day/night air temperatures were decreased from 30/20 to 10/0[deg]C, the osmotic pressure increased 0.10 MPa for O. ficus-indica and O. streptacantha but 0.38 MPa for O. humifusa. The increases in osmotic pressures were due mostly to the synthesis of fructose, glucose, and sucrose. In addition, O. humifusa produced a substantial amount of mannitol during exposure to low temperatures. Substantial accumulation of sugars and mannitol in cells of O. humifusa may help prevent intracellular freeze dehydration and ice formation as well as provide noncolligative protection to its membranes. Mucilage was slightly higher in all three species at the lower temperatures. Extracellular nucleation of ice occurred closer to the equilibrium freezing temperature for plants at 10/0[deg]C compared with 30/20[deg]C, which could make the cellular dehydration more gradual and, thus, less damaging. Results from nuclear magnetic resonance indicated a restricted mobility of intracellular water at the lower temperatures, especially for O. humifusa, which is consistent with its lower water content and higher levels of low molecular weight solutes.

  12. Enzymatic regulation of glycogenolysis in a subarctic population of the wood frog: implications for extreme freeze tolerance.

    Science.gov (United States)

    do Amaral, M Clara F; Lee, Richard E; Costanzo, Jon P

    2013-01-01

    The wood frog, Rana sylvatica, from Interior Alaska survives freezing at -16°C, a temperature 10-13°C below that tolerated by its southern conspecifics. We investigated the hepatic freezing response in this northern phenotype to determine if its profound freeze tolerance is associated with an enhanced glucosic cryoprotectant system. Alaskan frogs had a larger liver glycogen reserve that was mobilized faster during early freezing as compared to conspecifics from a cool-temperate region (southern Ohio, USA). In Alaskan frogs the rapid glucose production in the first hours of freezing was associated with a 7-fold increase in glycogen phosphorylase activity above unfrozen frog levels, and the activity of this enzyme was higher than that of frozen Ohioan frogs. Freezing of Ohioan frogs induced a more modest (4-fold) increase in glycogen phosphorylase activity above unfrozen frog values. Relative to the Ohioan frogs, Alaskan frogs maintained a higher total protein kinase A activity throughout an experimental freezing/thawing time course, and this may have potentiated glycogenolysis during early freezing. We found populational variation in the activity and protein level of protein kinase A which suggested that the Alaskan population had a more efficient form of this enzyme. Alaskan frogs modulated their glycogenolytic response by decreasing the activity of glycogen phosphorylase after cryoprotectant mobilization was well under way, thereby conserving their hepatic glycogen reserve. Ohioan frogs, however, sustained high glycogen phosphorylase activity until early thawing and consumed nearly all their liver glycogen. These unique hepatic responses of Alaskan R. sylvatica likely contribute to this phenotype's exceptional freeze tolerance, which is necessary for their survival in a subarctic climate.

  13. Enzymatic regulation of glycogenolysis in a subarctic population of the wood frog: implications for extreme freeze tolerance.

    Directory of Open Access Journals (Sweden)

    M Clara F do Amaral

    Full Text Available The wood frog, Rana sylvatica, from Interior Alaska survives freezing at -16°C, a temperature 10-13°C below that tolerated by its southern conspecifics. We investigated the hepatic freezing response in this northern phenotype to determine if its profound freeze tolerance is associated with an enhanced glucosic cryoprotectant system. Alaskan frogs had a larger liver glycogen reserve that was mobilized faster during early freezing as compared to conspecifics from a cool-temperate region (southern Ohio, USA. In Alaskan frogs the rapid glucose production in the first hours of freezing was associated with a 7-fold increase in glycogen phosphorylase activity above unfrozen frog levels, and the activity of this enzyme was higher than that of frozen Ohioan frogs. Freezing of Ohioan frogs induced a more modest (4-fold increase in glycogen phosphorylase activity above unfrozen frog values. Relative to the Ohioan frogs, Alaskan frogs maintained a higher total protein kinase A activity throughout an experimental freezing/thawing time course, and this may have potentiated glycogenolysis during early freezing. We found populational variation in the activity and protein level of protein kinase A which suggested that the Alaskan population had a more efficient form of this enzyme. Alaskan frogs modulated their glycogenolytic response by decreasing the activity of glycogen phosphorylase after cryoprotectant mobilization was well under way, thereby conserving their hepatic glycogen reserve. Ohioan frogs, however, sustained high glycogen phosphorylase activity until early thawing and consumed nearly all their liver glycogen. These unique hepatic responses of Alaskan R. sylvatica likely contribute to this phenotype's exceptional freeze tolerance, which is necessary for their survival in a subarctic climate.

  14. Effects of cold-hardening on compatible solutes and antioxidant enzyme activities related to freezing tolerance in Ammopiptanthus mongolicus seedlings

    Institute of Scientific and Technical Information of China (English)

    WANG Wei-juan; CHEN Yu-zhen; LIU Mei-qin; LU Cun-fu

    2008-01-01

    Cold acclimation is associated with many metabolic changes that lead to an increase of freezing tolerance. In order to investigate the biochemical process of cold acclimation in Ammopiptanthus mongolicus, seedlings were acclimated at 2℃ under 16-h photoperiod (150 μmol·m-2·s-1 photosynthetically active radiation) for 14 d. Freezing tolerance in seedlings increased after 14 d of cold-hardening. Contents of protein, proline and solute carbohydrate in cotyledon increased after cold acclimation. Patterns of isozymes of superoxide dismutase (SOD), peroxidase, catalase and polyphenol oxidase (PPO) were investigated. The activities of SOD, peroxidase and PPO in cold acclimated plants were increased during cold-hardening. We deduced that compatible solutes and antioxidant enzymes play important roles in development of freezing tolerance during cold acclimation in this evergreen woody plant.

  15. TaSK5, an abiotic stress-inducible GSK3/shaggy-like kinase from wheat, confers salt and drought tolerance in transgenic Arabidopsis.

    Science.gov (United States)

    Christov, Nikolai Kirilov; Christova, Petya Koeva; Kato, Hideki; Liu, Yuelin; Sasaki, Kentaro; Imai, Ryozo

    2014-11-01

    A novel cold-inducible GSK3/shaggy-like kinase, TaSK5, was isolated from winter wheat using a macroarray-based differential screening approach. TaSK5 showed high similarity to Arabidopsis subgroup I GSK3/shaggy-like kinases ASK-alpha, AtSK-gamma and ASK-epsilon. RNA gel blot analyses revealed TaSK5 induction by cold and NaCl treatments and to a lesser extent by drought treatment. TaSK5 functionally complemented the cold- and salt-sensitive phenotypes of a yeast GSK3/shaggy-like kinase mutant, △mck1. Transgenic Arabidopsis plants overexpressing TaSK5 cDNA showed enhanced tolerance to salt and drought stresses. By contrast, the tolerance of the transgenic plants to freezing stress was not altered. Microarray analysis revealed that a number of abiotic stress-inducible genes were constitutively induced in the transgenic Arabidopsis plants, suggesting that TaSK5 may function in a novel signal transduction pathway that appears to be unrelated to DREB1/CBF regulon and may involve crosstalk between abiotic and hormonal signals.

  16. Arabidopsis enhanced drought tolerance1/HOMEODOMAIN GLABROUS11 confers drought tolerance in transgenic rice without yield penalty.

    Science.gov (United States)

    Yu, Linhui; Chen, Xi; Wang, Zhen; Wang, Shimei; Wang, Yuping; Zhu, Qisheng; Li, Shigui; Xiang, Chengbin

    2013-07-01

    Enhancing drought tolerance without yield decrease has been a great challenge in crop improvement. Here, we report the Arabidopsis (Arabidopsis thaliana) homodomain-leucine zipper transcription factor Enhanced Drought Tolerance/HOMEODOMAIN GLABROUS11 (EDT1/HDG11) was able to confer drought tolerance and increase grain yield in transgenic rice (Oryza sativa) plants. The improved drought tolerance was associated with a more extensive root system, reduced stomatal density, and higher water use efficiency. The transgenic rice plants also had higher levels of abscisic acid, proline, soluble sugar, and reactive oxygen species-scavenging enzyme activities during stress treatments. The increased grain yield of the transgenic rice was contributed by improved seed setting, larger panicle, and more tillers as well as increased photosynthetic capacity. Digital gene expression analysis indicated that AtEDT1/HDG11 had a significant influence on gene expression profile in rice, which was consistent with the observed phenotypes of transgenic rice plants. Our study shows that AtEDT1/HDG11 can improve both stress tolerance and grain yield in rice, demonstrating the efficacy of AtEDT1/HDG11 in crop improvement.

  17. Genome wide association mapping for the tolerance to the polyamine oxidase inhibitor guazatine in Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Kostadin Evgeniev eAtanasov

    2016-04-01

    Full Text Available Guazatine is a potent inhibitor of polyamine oxidase (PAO activity. In agriculture, guazatine is used as non-systemic contact fungicide efficient in the protection of cereals and citrus fruits against disease. The composition of guazatine is complex, mainly constituted by a mixture of synthetic guanidated polyamines (polyaminoguanidines. Here we have studied the effects from exposure to guazatine in the weed Arabidopsis thaliana. We report that micromolar concentrations of guazatine are sufficient to inhibit growth of Arabidopsis seedlings and induce chlorosis, whereas germination is barely affected. We observed the occurrence of quantitative variation in the response to guazatine between 107 randomly chosen Arabidopsis accessions. This enabled us to undertake genome-wide association (GWA mapping that identified a locus on chromosome one associated with guazatine tolerance. CHLOROPHYLLASE 1 (CLH1 within this locus was studied as candidate gene, together with its paralog (CLH2. The analysis of independent clh1-2, clh1-3, clh2-3, clh2-2 and double clh1-2 clh2-3 mutant alleles indicated that CLH1 and/or CLH2 loss-of-function or expression down-regulation promote guazatine tolerance in Arabidopsis. We report a natural mechanism by which Arabidopsis populations can overcome toxicity by the fungicide guazatine.

  18. A comparative study of salt tolerance parameters in 11 wild relatives of Arabidopsis thaliana

    KAUST Repository

    Orsini, Francesco

    2010-07-01

    Salinity is an abiotic stress that limits both yield and the expansion of agricultural crops to new areas. In the last 20 years our basic understanding of the mechanisms underlying plant tolerance and adaptation to saline environments has greatly improved owing to active development of advanced tools in molecular, genomics, and bioinformatics analyses. However, the full potential of investigative power has not been fully exploited, because the use of halophytes as model systems in plant salt tolerance research is largely neglected. The recent introduction of halophytic Arabidopsis-Relative Model Species (ARMS) has begun to compare and relate several unique genetic resources to the well-developed Arabidopsis model. In a search for candidates to begin to understand, through genetic analyses, the biological bases of salt tolerance, 11 wild relatives of Arabidopsis thaliana were compared: Barbarea verna, Capsella bursa-pastoris, Hirschfeldia incana, Lepidium densiflorum, Malcolmia triloba, Lepidium virginicum, Descurainia pinnata, Sisymbrium officinale, Thellungiella parvula, Thellungiella salsuginea (previously T. halophila), and Thlaspi arvense. Among these species, highly salt-tolerant (L. densiflorum and L. virginicum) and moderately salt-tolerant (M. triloba and H. incana) species were identified. Only T. parvula revealed a true halophytic habitus, comparable to the better studied Thellungiella salsuginea. Major differences in growth, water transport properties, and ion accumulation are observed and discussed to describe the distinctive traits and physiological responses that can now be studied genetically in salt stress research. 2010 The Author.

  19. ABA Inducible Rice Protein Phosphatase 2C Confers ABA Insensitivity and Abiotic Stress Tolerance in Arabidopsis

    Science.gov (United States)

    Singh, Amarjeet; Jha, Saroj K.; Bagri, Jayram; Pandey, Girdhar K.

    2015-01-01

    Arabidopsis PP2C belonging to group A have been extensively worked out and known to negatively regulate ABA signaling. However, rice (Oryza sativa) orthologs of Arabidopsis group A PP2C are scarcely characterized functionally. We have identified a group A PP2C from rice (OsPP108), which is highly inducible under ABA, salt and drought stresses and localized predominantly in the nucleus. Genetic analysis revealed that Arabidopsis plants overexpressing OsPP108 are highly insensitive to ABA and tolerant to high salt and mannitol stresses during seed germination, root growth and overall seedling growth. At adult stage, OsPP108 overexpression leads to high tolerance to salt, mannitol and drought stresses with far better physiological parameters such as water loss, fresh weight, chlorophyll content and photosynthetic potential (Fv/Fm) in transgenic Arabidopsis plants. Expression profile of various stress marker genes in OsPP108 overexpressing plants revealed interplay of ABA dependent and independent pathway for abiotic stress tolerance. Overall, this study has identified a potential rice group A PP2C, which regulates ABA signaling negatively and abiotic stress signaling positively. Transgenic rice plants overexpressing this gene might provide an answer to the problem of low crop yield and productivity during adverse environmental conditions. PMID:25886365

  20. Physiological Mechanisms Only Tell Half Story: Multiple Biological Processes are involved in Regulating Freezing Tolerance of Imbibed Lactuca sativa Seeds.

    Science.gov (United States)

    Jaganathan, Ganesh K; Han, Yingying; Li, Weijie; Song, Danping; Song, Xiaoyan; Shen, Mengqi; Zhou, Qiang; Zhang, Chenxue; Liu, Baolin

    2017-03-13

    The physiological mechanisms by which imbibed seeds survive freezing temperatures in their natural environment have been categorized as freezing avoidance by supercooling and freezing tolerance by extracellular freeze-desiccation, but the biochemical and molecular mechanisms conferring seed freezing tolerance is unexplored. In this study, using imbibed Lactuca sativa seeds we show that fast cooled seeds (60 °C h(-1)) suffered significantly higher membrane damage at temperature between -20 °C and -10 °C than slow cooled (3 °Ch(-1)) seeds (P  0.05). However, both SOD activity and accumulation of free proline were induced significantly after slow cooling to -20 °C compared with fast cooling. RNA-seq demonstrated that multiple pathways were differentially regulated between slow and fast cooling. Real-time verification of some differentially expressed genes (DEGs) revealed that fast cooling caused mRNA level changes of plant hormone and ubiquitionation pathways at higher sub-zero temperature, whilst slow cooling caused mRNA level change of those pathways at lower sub-zero ttemperatures. Thus, we conclude that imbibed seed tolerate low temperature not only by physiological mechanisms but also by biochemical and molecular changes.

  1. Overexpression of SOS (Salt Overly Sensitive)Genes Increases Salt Tolerance in Transgenic Arabidopsis

    Institute of Scientific and Technical Information of China (English)

    Qing Yang; Zhi-Zhong Chen; Xiao-Feng Zhoua; Hai-Bo Yin; Xia Li; Xiu-Fang Xin; Xu-Hui Hong; Jian-Kang Zhu; Zhizhong Gong

    2009-01-01

    Soil salinity is a major abiotic stress that decreases plant growth and productivity. Recently, it was reported that plants overexpressing AtNHX1 or SOS1 have significantly increased salt tolerance. To test whether overexpression of multiple genes can improve plant salt tolerance even more, we produced six different transgenic Arabidopsis plants that overexpress AtNHX1, SOS3, AtNHXl + SOS3, SOS1, SOS2 + SOS3, or SOS1 + SOS2 + SOS3. Northern blot analyses confirmed the presence of high levels of the relevant gene transcripts in transgenic plants. Transgenic Arabidopsis plants overexpressing AtNHX1 alone did not present any significant increase in salt tolerance, contrary to earlier reports. We found that transgenic plants overexpressing SOS3 exhibit increased salt tolerance similar to plants overexpressing SOS1. Moreover, salt tolerance of transgenic plants overexpressing AtNHXl + SOS3, 50S2 + SOS3, or SOS1 + SOS2 +SOS3, respectively, appeared similar to the tolerance of transgenic plants overexpressing either SOS1 or SOS3 alone.

  2. Effect of Hexaconazole and Penconazole on Kochia (Kochia scoparia Freezing Tolerance

    Directory of Open Access Journals (Sweden)

    A. Kamandy

    2016-07-01

    Full Text Available Introduction Cold and freezing are the most important limiting factors on development of sensitive plants. When the ambient temperature deviates from optimal, physiological, and biochemical, metabolic and molecular changes will occur within plants. This is an effort of plants to maximize growth and developmental processes and to maintain cellular homeostasis during such adverse conditions. At the extremes of the natural temperature range of plant, the degree of physiological, cellular, metabolic and molecular dysfunction becomes so severe that it leads to death. Triazoles are the most potent groups of growth retardants with multiple effects. Plant growing with paclobutrazol generally has little effect on rates of net photosynthetic rate. However, because the compound reduces leaf area, net photosynthesis on a per plant basis is probably reduced. They have exhibited growth regulating, fungicidal, herbicidal, apicidal and antibacterial activities. More recently, it was found that triazole compounds are able to increase tolerance of plants to cold and freezing stress. Kochia (Kochia scoparia (L. Schrad., an out crossing species whose pollen move between plants in windy areas, has recently been considered as a forage or fodder crop in marginal lands. Steppuhn and Wall (1993 claimed that Kochia offers great potential as a crop that can be grown on saline soils, yielding fodder in quantities approaching that produced by alfalfa (Medicago sativa L.. Shamsutdinov et al. (1996 also reported more than 15 Mg ha-1 dry-matter production for Kochia under saline conditions and concluded that it is a good candidate for forage hay. Thus, the aim of the present study was to determine whether the triazole compounds could increase tolerance of kochia against freezing stress. Materials and Methods An experiment was carried out with hexaconazole and penconazole in 0, 10 and 20 mg.L-1 and freezing temperatures 0, -2, -4, -6 and -8 degree centigrade in factorial based

  3. Functional characterization of aroA from Rhizobium leguminosarum with significant glyphosate tolerance in transgenic Arabidopsis.

    Science.gov (United States)

    Han, Jing; Tian, Yong-Sheng; Xu, Jing; Wang, Li-Juan; Wang, Bo; Peng, Ri-He; Yao, Quan-Hong

    2014-09-01

    Glyphosate is the active component of the top-selling herbicide, the phytotoxicity of which is due to its inhibition of the shikimic acid pathway. 5-Enolpyruvylshikimate-3-phosphate synthase (EPSPS) is a key enzyme in the shikimic acid pathway. Glyphosate tolerance in plants can be achieved by the expression of a glyphosate-insensitive aroA gene (EPSPS). In this study, we used a PCR-based two-step DNA synthesis method to synthesize a new aroA gene (aroAR. leguminosarum) from Rhizobium leguminosarum. In vitro glyphosate sensitivity assays showed that aroAR. leguminosarum is glyphosate tolerant. The new gene was then expressed in E. coli and key kinetic values of the purified enzyme were determined. Furthermore, we transformed the aroA gene into Arabidopsis thaliana by the floral dip method. Transgenic Arabidopsis with the aroAR. leguminosarum gene was obtained to prove its potential use in developing glyphosate-resistant crops.

  4. Stability evaluation of freeze-dried Lactobacillus paracasei subsp. tolerance and Lactobacillus delbrueckii subsp. bulgaricus in oral capsules.

    Science.gov (United States)

    Jalali, M; Abedi, D; Varshosaz, J; Najjarzadeh, M; Mirlohi, M; Tavakoli, N

    2012-01-01

    Freeze-drying is a common preservation technology in the pharmaceutical industry. Various studies have investigated the effect of different cryoprotectants on probiotics during freeze-drying. However, information on the effect of cryoprotectants on the stability of some Lactobacillus strains during freeze-drying seems scarce. Therefore, the aim of the present study was to establish production methods for preparation of oral capsule probiotics containing Lactobacillus paracasei subsp. tolerance and Lactobacillus delbrueckii subsp. Bulgaricus. It was also of interest to examine the effect of various formulations of cryoprotectant media containing skim milk, trehalose and sodium ascorbate on the survival rate of probiotic bacteria during freeze-drying at various storage temperatures. Without any cryoprotectant, few numbers of microorganisms survived. However, microorganisms tested maintained higher viability after freeze-drying in media containing at least one of the cryoprotectants. Use of skim milk in water resulted in an increased viability after lyophilization. Media with a combination of trehalose and skim milk maintained a higher percentage of live microorganisms, up to 82%. In general, bacteria retained a higher number of viable cells in capsules containing freeze-dried bacteria with sodium ascorbate after three months of storage. After this period, a marked decline was observed in all samples stored at 23°C compared to those stored at 4°C. The maximum survival rate (about 72-76%) was observed with media containing 6% skim milk, 8% trehalose and 4% sodium ascorbate.

  5. Brassica oleracea MATE encodes a citrate transporter and enhances aluminum tolerance in Arabidopsis thaliana.

    Science.gov (United States)

    Wu, Xinxin; Li, Ren; Shi, Jin; Wang, Jinfang; Sun, Qianqian; Zhang, Haijun; Xing, Yanxia; Qi, Yan; Zhang, Na; Guo, Yang-Dong

    2014-08-01

    The secretion of organic acid anions from roots is an important mechanism for plant aluminum (Al) tolerance. Here we report cloning and characterizing BoMATE (KF031944), a multidrug and toxic compound extrusion (MATE) family gene from cabbage (Brassica oleracea). The expression of BoMATE was more abundant in roots than in shoots, and it was highly induced by Al treatment. The (14)C-citrate efflux experiments in oocytes demonstrated that BoMATE is a citrate transporter. Electrophysiological analysis and SIET analysis of Xenopus oocytes expressing BoMATE indicated BoMATE is activated by Al. Transient expression of BoMATE in onion epidermal cells demonstrated that it localized to the plasma membrane. Compared with the wild-type Arabidopsis, the transgenic lines constitutively overexpressing BoMATE enhanced Al tolerance and increased citrate secretion. In addition, Arabidopsis transgenic lines had a lower K(+) efflux and higher H(+) efflux, in the presence of Al, than control wild type in the distal elongation zone (DEZ). This is the first direct evidence that MATE protein is involved in the K(+) and H(+) flux in response to Al treatment. Taken together, our results show that BoMATE is an Al-induced citrate transporter and enhances aluminum tolerance in Arabidopsis thaliana.

  6. Potassium Retention under Salt Stress Is Associated with Natural Variation in Salinity Tolerance among Arabidopsis Accessions.

    Directory of Open Access Journals (Sweden)

    Yanling Sun

    Full Text Available Plants are exposed to various environmental stresses during their life cycle such as salt, drought and cold. Natural variation mediated plant growth adaptation has been employed as an effective approach in response to the diverse environmental cues such as salt stress. However, the molecular mechanism underlying this process is not well understood. In the present study, a collection of 82 Arabidopsis thaliana accessions (ecotypes was screened with a view to identify variation for salinity tolerance. Seven accessions showed a higher level of tolerance than Col-0. The young seedlings of the tolerant accessions demonstrated a higher K(+ content and a lower Na(+/K(+ ratio when exposed to salinity stress, but its Na(+ content was the same as that of Col-0. The K(+ transporter genes AtHAK5, AtCHX17 and AtKUP1 were up-regulated significantly in almost all the tolerant accessions, even in the absence of salinity stress. There was little genetic variation or positive transcriptional variation between the selections and Col-0 with respect to Na+-related transporter genes, as AtSOS genes, AtNHX1 and AtHKT1;1. In addition, under salinity stress, these selections accumulated higher compatible solutes and lower reactive oxygen species than did Col-0. Taken together, our results showed that natural variation in salinity tolerance of Arabidopsis seems to have been achieved by the strong capacity of K(+ retention.

  7. Group 1 LEA proteins contribute to the desiccation and freeze tolerance of Artemia franciscana embryos during diapause.

    Science.gov (United States)

    Toxopeus, Jantina; Warner, Alden H; MacRae, Thomas H

    2014-11-01

    Water loss either by desiccation or freezing causes multiple forms of cellular damage. The encysted embryos (cysts) of the crustacean Artemia franciscana have several molecular mechanisms to enable anhydrobiosis-life without water-during diapause. To better understand how cysts survive reduced hydration, group 1 late embryogenesis abundant (LEA) proteins, hydrophilic unstructured proteins that accumulate in the stress-tolerant cysts of A. franciscana, were knocked down using RNA interference (RNAi). Embryos lacking group 1 LEA proteins showed significantly lower survival than control embryos after desiccation and freezing, or freezing alone, demonstrating a role for group 1 LEA proteins in A. franciscana tolerance of low water conditions. In contrast, regardless of group 1 LEA protein presence, cysts responded similarly to hydrogen peroxide (H2O2) exposure, indicating little to no function for these proteins in diapause termination. This is the first in vivo study of group 1 LEA proteins in an animal and it contributes to the fundamental understanding of these proteins. Knowing how LEA proteins protect A. franciscana cysts from desiccation and freezing may have applied significance in aquaculture, where Artemia is an important feed source, and in the cryopreservation of cells for therapeutic applications.

  8. An Autophosphorylation Site of the Protein Kinase SOS2 Is Important for Salt Tolerance in Arabidopsis

    Institute of Scientific and Technical Information of China (English)

    Hiroaki Fujii; Jian-Kang Zhu

    2009-01-01

    The protein kinase SOS2 (Salt Overly Sensitive 2) is essential for salt-stress signaling and tolerance in Arabidopsis. SOS2 is known to be activated by calcium-SOS3 and by phosphorylation at its activation loop. SOS2 is autophosphorylated in vitro, but the autophosphorylation site and its role in salt tolerance are not known. In this study, we identified an autophosphorylation site in SOS2 and analyzed its role in the responses of Arabidopsis to salt stress. Mass spectrometry analysis showed that Ser 228 of SOS2 is autophosphorylated. When this site was mutated to Ala, the autophosphorylation rate of SOS2 decreased. The substrate phosphorylation by the mutated SOS2 was also less than that by the wild-type SOS2. In contrast, changing Ser228 to Asp to mimic the autophosphorylation enhanced substrate phosphorylation by SOS2. Complementation tests in a sos2 mutant showed that the S228A but not the S228D mutation partially disrupted the function of SOS2 in salt tolerance. We also show that activation loop phosphorylation at Thr168 and autophosphorylation at Ser228 cannot substitute for each other, suggesting that both are required for salt tolerance. Our results indicate that Ser 228 of SOS2 is autophosphorylated and that this autophosphorylation is important for SOS2 function under salt stress.

  9. Irradiation with low-dose gamma ray enhances tolerance to heat stress in Arabidopsis seedlings.

    Science.gov (United States)

    Zhang, Liang; Zheng, Fengxia; Qi, Wencai; Wang, Tianqi; Ma, Lingyu; Qiu, Zongbo; Li, Jingyuan

    2016-06-01

    Gamma irradiation at low doses can stimulate the tolerance to environmental stress in plants. However, the knowledge regarding the mechanisms underlying the enhanced tolerance induced by low-dose gamma irradiation is far from fully understood. In this study, to investigate the physiological and molecular mechanisms of heat stress alleviated by low-dose gamma irradiation, the Arabidopsis seeds were exposed to a range of doses before subjected to heat treatment. Our results showed that 50-Gy gamma irradiation maximally promoted seedling growth in response to heat stress. The production rate of superoxide radical and contents of hydrogen peroxide and malondialdehyde in the seedlings irradiated with 50-Gy dose under heat stress were significantly lower than those of controls. The activities of antioxidant enzymes, glutathione (GSH) content and proline level in the gamma-irradiated seedlings were significantly increased compared with the controls. Furthermore, transcriptional expression analysis of selected genes revealed that some components related to heat tolerance were stimulated by low-dose gamma irradiation under heat shock. Our results suggest that low-dose gamma irradiation can modulate the physiological responses as well as gene expression related to heat tolerance, thus alleviating the stress damage in Arabidopsis seedlings.

  10. Anatomical Structure Comparison Between Leaves of Two Winter Wheat Cultivars with Different Cold/Freezing Tolerance Under Low Temperature Stress

    Institute of Scientific and Technical Information of China (English)

    YU Jing; CANG Jing; ZHOU Zishan; LIU Lijie

    2011-01-01

    Winter wheat (Triticum aestivum) cultivars Dongnongdongmai 1 with strong cold/freezing tolerance and Jimai 22 with weak cold/freezing tolerance were used for investigating the difference of microstructure and ultrastructure between leaves of two cultivars under low temperature stress (5℃ and -15 ℃) using optical and electron microscope. The results showed that there was no obvious difference between leaves of Dongnongdongmai 1 and Jimai 22 in microstructure. However, the difference between those leaves was distinct in ultrastructure. The grana lamella and stroma lamella were stacked regularly and arranged parallelly along the long axis of chloroplasts in cv. Dongnongdongmai 1, while the arrangement directions of thylakoids in Jimai 22's leaves were so irregular as to form various angles with the long axis of chloroplasts. At -15℃, the mitochondrias were swelled to be round and the structure of cristaes became blurry in both cultivars' leaves, while some cristaes of Jimai 22 disappeared. These results would provide theoretical evidence for selecting cold/freezing tolerant winter wheat germplasm resources

  11. Ectopic expression of Arabidopsis RCI2A gene contributes to cold tolerance in tomato.

    Science.gov (United States)

    Sivankalyani, Velu; Geetha, Mahalingam; Subramanyam, Kondeti; Girija, Shanmugam

    2015-04-01

    Cold is a major stress that limits the quality and productivity of economically important crops such as tomato (Solanum lycopersicum L.). Generating a cold-stress-tolerant tomato by expressing cold-inducible genes would increase agricultural strategies. Rare cold-inducible 2a (RCI2A) is expressed in Arabidopsis, but its molecular function during cold stress is not fully understood. Here we ectopically expressed Arabidopsis RCI2A in transgenic tomato to evaluate tolerance to cold stress without altering agronomic traits. Biochemical and physiological study demonstrated that expression of RCI2A in transgenic tomato enhanced the activity of peroxidase and ascorbate peroxidase (APX) and reduced the accumulation of H2O2, alleviated lipid peroxidation, increased the accumulation of chlorophyll, reduced chilling-induced membrane damage, retained relative water content and enhanced cold tolerance. A motif search revealed that the motifs of photosystem II (PSII) phosphoproteins PsbJ and PsbH and reaction-center proteins PsbL and PsbK were common to cold-inducible RCI2A and peroxidase proteins RCI3A, tomato peroxidase (TPX1), TPX2, tomato ascorbate peroxidase (APX1), and horseradish peroxidase (HRP-c). In addition to membrane protection, RCI2A may cross talk with PSII-associated proteins or peroxidase family enzymes in response to cold stress. Our findings may strengthen the understanding of the molecular function of RCI2A in cold-stress tolerance. RCI2A could be used to improve abiotic stress tolerance in agronomic crops.

  12. Expression of Vitis amurensis NAC26 in Arabidopsis enhances drought tolerance by modulating jasmonic acid synthesis.

    Science.gov (United States)

    Fang, Linchuan; Su, Lingye; Sun, Xiaoming; Li, Xinbo; Sun, Mengxiang; Karungo, Sospeter Karanja; Fang, Shuang; Chu, Jinfang; Li, Shaohua; Xin, Haiping

    2016-04-01

    The growth and fruit quality of grapevines are widely affected by abnormal climatic conditions such as water deficits, but many of the precise mechanisms by which grapevines respond to drought stress are still largely unknown. Here, we report that VaNAC26, a member of the NAC transcription factor family, was upregulated dramatically during cold, drought and salinity treatments in Vitis amurensis, a cold and drought-hardy wild Vitis species. Heterologous overexpression of VaNAC26 enhanced drought and salt tolerance in transgenic Arabidopsis. Higher activities of antioxidant enzymes and lower concentrations of H2O2 and O2 (-) were found in VaNAC26-OE lines than in wild type plants under drought stress. These results indicated that scavenging by reactive oxygen species (ROS) was enhanced by VaNAC26 in transgenic lines. Microarray-based transcriptome analysis revealed that genes related to jasmonic acid (JA) synthesis and signaling were upregulated in VaNAC26-OE lines under both normal and drought conditions. VaNAC26 showed a specific binding ability on the NAC recognition sequence (NACRS) motif, which broadly exists in the promoter regions of upregulated genes in transgenic lines. Endogenous JA content significantly increased in the VaNAC26-OE lines 2 and 3. Our data suggest that VaNAC26 responds to abiotic stresses and may enhance drought tolerance by transcriptional regulation of JA synthesis in Arabidopsis.

  13. Expression of Vitis amurensis NAC26 in Arabidopsis enhances drought tolerance by modulating jasmonic acid synthesis

    Science.gov (United States)

    Fang, Linchuan; Su, Lingye; Sun, Xiaoming; Li, Xinbo; Sun, Mengxiang; Karungo, Sospeter Karanja; Fang, Shuang; Chu, Jinfang; Li, Shaohua; Xin, Haiping

    2016-01-01

    The growth and fruit quality of grapevines are widely affected by abnormal climatic conditions such as water deficits, but many of the precise mechanisms by which grapevines respond to drought stress are still largely unknown. Here, we report that VaNAC26, a member of the NAC transcription factor family, was upregulated dramatically during cold, drought and salinity treatments in Vitis amurensis, a cold and drought-hardy wild Vitis species. Heterologous overexpression of VaNAC26 enhanced drought and salt tolerance in transgenic Arabidopsis. Higher activities of antioxidant enzymes and lower concentrations of H2O2 and O2 − were found in VaNAC26-OE lines than in wild type plants under drought stress. These results indicated that scavenging by reactive oxygen species (ROS) was enhanced by VaNAC26 in transgenic lines. Microarray-based transcriptome analysis revealed that genes related to jasmonic acid (JA) synthesis and signaling were upregulated in VaNAC26-OE lines under both normal and drought conditions. VaNAC26 showed a specific binding ability on the NAC recognition sequence (NACRS) motif, which broadly exists in the promoter regions of upregulated genes in transgenic lines. Endogenous JA content significantly increased in the VaNAC26-OE lines 2 and 3. Our data suggest that VaNAC26 responds to abiotic stresses and may enhance drought tolerance by transcriptional regulation of JA synthesis in Arabidopsis. PMID:27162276

  14. ars1, an Arabidopsis mutant exhibiting increased tolerance to arsenate and increased phosphate uptake.

    Science.gov (United States)

    Lee, David A; Chen, Alice; Schroeder, Julian I

    2003-09-01

    Arsenic is one of the most toxic pollutants at contaminated sites, yet little is known about the mechanisms by which certain plants survive exposure to high arsenic levels. To gain insight into the mechanisms of arsenic tolerance in plants, we developed a genetic screen to isolate Arabidopsis thaliana mutants with altered tolerance to arsenic. We report here on the isolation of a mutant arsenic resisant 1 (ars1) with increased tolerance to arsenate. ars1 germinates and develops under conditions that completely inhibit growth of wild-type plants and shows a semi-dominant arsenic resistance phenotype. ars1 accumulates levels of arsenic similar to that accumulated by wild-type plants, suggesting that ars1 plants have an increased ability to detoxify arsenate. However, ars1 plants produce phytochelatin levels similar to levels produced by the wild type, and the enhanced resistance of ars1 is not abolished by the gamma-glutamylcysteine synthetase inhibitor l-buthionine sulfoxime (BSO). Furthermore, ars1 plants do not show resistance to arsenite or other toxic metals such as cadmium and chromium. However, ars1 plants do show a higher rate of phosphate uptake than that shown by wild-type plants, and wild-type plants grown with an excess of phosphate show increased tolerance to arsenate. Traditional models of arsenate tolerance in plants are based on the suppression of phosphate uptake pathways and consequently on the reduced uptake of arsenate. Our data suggest that arsenate tolerance in ars1 could be due to a new mechanism mediated by increased phosphate uptake in ars1. Models discussing how increased phosphate uptake could contribute to arsenate tolerance are discussed.

  15. A cellulose synthase-like protein is required for osmotic stress tolerance in Arabidopsis

    KAUST Repository

    Zhu, Jianhua

    2010-04-16

    Osmotic stress imposed by soil salinity and drought stress significantly affects plant growth and development, but osmotic stress sensing and tolerance mechanisms are not well understood. Forward genetic screens using a root-bending assay have previously identified salt overly sensitive (sos) mutants of Arabidopsis that fall into five loci, SOS1 to SOS5. These loci are required for the regulation of ion homeostasis or cell expansion under salt stress, but do not play a major role in plant tolerance to the osmotic stress component of soil salinity or drought. Here we report an additional sos mutant, sos6-1, which defines a locus essential for osmotic stress tolerance. sos6-1 plants are hypersensitive to salt stress and osmotic stress imposed by mannitol or polyethylene glycol in culture media or by water deficit in the soil. SOS6 encodes a cellulose synthase-like protein, AtCSLD5. Only modest differences in cell wall chemical composition could be detected, but we found that sos6-1 mutant plants accumulate high levels of reactive oxygen species (ROS) under osmotic stress and are hypersensitive to the oxidative stress reagent methyl viologen. The results suggest that SOS6/AtCSLD5 is not required for normal plant growth and development but has a critical role in osmotic stress tolerance and this function likely involves its regulation of ROS under stress. © 2010 Blackwell Publishing Ltd.

  16. Improved Growth and Stress Tolerance in the Arabidopsis oxt1 Mutant Triggered by Altered Adenine Metabolism

    Institute of Scientific and Technical Information of China (English)

    Suchada Sukrong; Kil-Young Yun; Patrizia Stadler; Charan Kumar; Tony Facciuolo; Barbara A.Moffatt; Deane L.Falcone

    2012-01-01

    Plants perceive and respond to environmental stresses with complex mechanisms that are often associated with the activation of antioxidant defenses.A genetic screen aimed at isolating oxidative stress-tolerant lines of Arabidopsis thaliana has identified oxt1,a line that exhibits improved tolerance to oxidative stress and elevated temperature but displays no apparent deleterious growth effects under non-stress conditions.Oxt1 harbors a mutation that arises from the altered expression of a gene encoding adenine phosphoribosyltransferase (APT1),an enzyme that converts adenine to adenosine monophosphate (AMP),indicating a link between purine metabolism,whole-plant growth responses,and stress acclimation.The oxt1 mutation results in decreased APT1 expression that leads to reduced enzymatic activity.Correspondingly,oxt1 plants possess elevated levels of adenine.Decreased APT enzyme activity directly correlates with stress resistance in transgenic lines that ectopically express APT1.The metabolic alteration in oxt1 plants also alters the expression of several antioxidant defense genes and the response of these genes to oxidative challenge.Finally,it is shown that manipulation of adenine levels can induce stress tolerance to wild-type plants.Collectively,these results show that alterations in cellular adenine levels can trigger stress tolerance and improve growth,leading to increases in plant biomass.The results also suggest that adenine might play a part in the signals that modulate responses to abiotic stress and plant growth.

  17. Interact to survive: Phyllobacterium brassicacearum improves Arabidopsis tolerance to severe water deficit and growth recovery.

    Directory of Open Access Journals (Sweden)

    Justine Bresson

    Full Text Available Mutualistic bacteria can alter plant phenotypes and confer new abilities to plants. Some plant growth-promoting rhizobacteria (PGPR are known to improve both plant growth and tolerance to multiple stresses, including drought, but reports on their effects on plant survival under severe water deficits are scarce. We investigated the effect of Phyllobacterium brassicacearum STM196 strain, a PGPR isolated from the rhizosphere of oilseed rape, on survival, growth and physiological responses of Arabidopsis thaliana to severe water deficits combining destructive and non-destructive high-throughput phenotyping. Soil inoculation with STM196 greatly increased the survival rate of A. thaliana under several scenarios of severe water deficit. Photosystem II efficiency, assessed at the whole-plant level by high-throughput fluorescence imaging (Fv/Fm, was related to the probability of survival and revealed that STM196 delayed plant mortality. Inoculated surviving plants tolerated more damages to the photosynthetic tissues through a delayed dehydration and a better tolerance to low water status. Importantly, STM196 allowed a better recovery of plant growth after rewatering and stressed plants reached a similar biomass at flowering than non-stressed plants. Our results highlight the importance of plant-bacteria interactions in plant responses to severe drought and provide a new avenue of investigations to improve drought tolerance in agriculture.

  18. Soybean GmPHD-type transcription regulators improve stress tolerance in transgenic Arabidopsis plants.

    Directory of Open Access Journals (Sweden)

    Wei Wei

    Full Text Available BACKGROUND: Soybean [Glycine max (L. Merr.] is one of the most important crops for oil and protein resource. Improvement of stress tolerance will be beneficial for soybean seed production. PRINCIPAL FINDINGS: Six GmPHD genes encoding Alfin1-type PHD finger protein were identified and their expressions differentially responded to drought, salt, cold and ABA treatments. The six GmPHDs were nuclear proteins and showed ability to bind the cis-element "GTGGAG". The N-terminal domain of GmPHD played a major role in DNA binding. Using a protoplast assay system, we find that GmPHD1 to GmPHD5 had transcriptional suppression activity whereas GmPHD6 did not have. In yeast assay, the GmPHD6 can form homodimer and heterodimer with the other GmPHDs except GmPHD2. The N-terminal plus the variable regions but not the PHD-finger is required for the dimerization. Transgenic Arabidopsis plants overexpressing the GmPHD2 showed salt tolerance when compared with the wild type plants. This tolerance was likely achieved by diminishing the oxidative stress through regulation of downstream genes. SIGNIFICANCE: These results provide important clues for soybean stress tolerance through manipulation of PHD-type transcription regulator.

  19. Ky-2, a Histone Deacetylase Inhibitor, Enhances High-Salinity Stress Tolerance in Arabidopsis thaliana.

    Science.gov (United States)

    Sako, Kaori; Kim, Jong-Myong; Matsui, Akihiro; Nakamura, Kotaro; Tanaka, Maho; Kobayashi, Makoto; Saito, Kazuki; Nishino, Norikazu; Kusano, Miyako; Taji, Teruaki; Yoshida, Minoru; Seki, Motoaki

    2016-04-01

    Adaptation to environmental stress requires genome-wide changes in gene expression. Histone modifications are involved in gene regulation, but the role of histone modifications under environmental stress is not well understood. To reveal the relationship between histone modification and environmental stress, we assessed the effects of inhibitors of histone modification enzymes during salinity stress. Treatment with Ky-2, a histone deacetylase inhibitor, enhanced high-salinity stress tolerance in Arabidopsis. We confirmed that Ky-2 possessed inhibition activity towards histone deacetylases by immunoblot analysis. To investigate how Ky-2 improved salt stress tolerance, we performed transcriptome and metabolome analysis. These data showed that the expression of salt-responsive genes and salt stress-related metabolites were increased by Ky-2 treatment under salinity stress. A mutant deficient in AtSOS1(Arabidopis thaliana SALT OVERLY SENSITIVE 1), which encodes an Na(+)/H(+)antiporter and was among the up-regulated genes, lost the salinity stress tolerance conferred by Ky-2. We confirmed that acetylation of histone H4 at AtSOS1 was increased by Ky-2 treatment. Moreover, Ky-2 treatment decreased the intracellular Na(+)accumulation under salinity stress, suggesting that enhancement of SOS1-dependent Na(+)efflux contributes to increased high-salinity stress tolerance caused by Ky-2 treatment.

  20. Overexpressing Arabidopsis ABF3 increases tolerance to multiple abiotic stresses and reduces leaf size in alfalfa.

    Science.gov (United States)

    Wang, Zhi; Su, Guoxia; Li, Min; Ke, Qingbo; Kim, Soo Young; Li, Hongbing; Huang, Jin; Xu, Bingcheng; Deng, Xi-Ping; Kwak, Sang-Soo

    2016-12-01

    Arabidopsis ABSCISIC ACID-RESPONSIVE ELEMENT-BINDING FACTOR 3 (ABF3), a bZIP transcription factor, plays an important role in regulating multiple stress responses in plants. Overexpressing AtABF3 increases tolerance to various stresses in several plant species. Alfalfa (Medicago sativa L.), one of the most important perennial forage crops worldwide, has high yields, high nutritional value, and good palatability and is widely distributed in irrigated and semi-arid regions throughout the world. However, drought and salt stress pose major constraints to alfalfa production. In this study, we developed transgenic alfalfa plants (cv. Xinjiang Daye) expressing AtABF3 under the control of the sweetpotato oxidative stress-inducible SWPA2 promoter (referred to as SAF plants) via Agrobacterium tumefaciens-mediated transformation. After drought stress treatment, we selected two transgenic lines with high expression of AtABF3, SAF5 and SAF6, for further characterization. Under normal conditions, SAF plants showed smaller leaf size compared to non-transgenic (NT) plants, while no other morphological changes were observed. Moreover, SAF plants exhibited enhanced drought stress tolerance and better growth under drought stress treatment, which was accompanied by a reduced transpiration rate and lower reactive oxygen species contents. In addition, SAF plants showed an increased tolerance to salt and oxidative stress. Therefore, these transgenic AtABF3 alfalfa plants might be useful for breeding forage crops with enhanced tolerance to environmental stress for use in sustainable agriculture on marginal lands.

  1. RAS1, a quantitative trait locus for salt tolerance and ABA sensitivity in Arabidopsis

    KAUST Repository

    Ren, Zhonghai

    2010-03-08

    Soil salinity limits agricultural production and is a major obstacle for feeding the growing world population. We used natural genetic variation in salt tolerance among different Arabidopsis accessions to map a major quantitative trait locus (QTL) for salt tolerance and abscisic acid (ABA) sensitivity during seed germination and early seedling growth. A recombinant inbred population derived from Landsberg erecta (Ler; salt and ABA sensitive) x Shakdara (Sha; salt and ABA resistant) was used for QTL mapping. High-resolution mapping and cloning of this QTL, Response to ABA and Salt 1 (RAS1), revealed that it is an ABA- and salt stress-inducible gene and encodes a previously undescribed plant-specific protein. A premature stop codon results in a truncated RAS1 protein in Sha. Reducing the expression of RAS1 by transfer-DNA insertion in Col or RNA interference in Ler leads to decreased salt and ABA sensitivity, whereas overexpression of the Ler allele but not the Sha allele causes increased salt and ABA sensitivity. Our results suggest that RAS1 functions as a negative regulator of salt tolerance during seed germination and early seedling growth by enhancing ABA sensitivity and that its loss of function contributes to the increased salt tolerance of Sha.

  2. Transcriptome profiling of genes and pathways associated with arsenic toxicity and tolerance in Arabidopsis

    Science.gov (United States)

    2014-01-01

    Background Arsenic (As) is a toxic metalloid found ubiquitously in the environment and widely considered an acute poison and carcinogen. However, the molecular mechanisms of the plant response to As and ensuing tolerance have not been extensively characterized. Here, we report on transcriptional changes with As treatment in two Arabidopsis accessions, Col-0 and Ws-2. Results The root elongation rate was greater for Col-0 than Ws-2 with As exposure. Accumulation of As was lower in the more tolerant accession Col-0 than in Ws-2. We compared the effect of As exposure on genome-wide gene expression in the two accessions by comparative microarray assay. The genes related to heat response and oxidative stresses were common to both accessions, which indicates conserved As stress-associated responses for the two accessions. Most of the specific response genes encoded heat shock proteins, heat shock factors, ubiquitin and aquaporin transporters. Genes coding for ethylene-signalling components were enriched in As-tolerant Col-0 with As exposure. A tolerance-associated gene candidate encoding Leucine-Rich Repeat receptor-like kinase VIII (LRR-RLK VIII) was selected for functional characterization. Genetic loss-of-function analysis of the LRR-RLK VIII gene revealed altered As sensitivity and the metal accumulation in roots. Conclusions Thus, ethylene-related pathways, maintenance of protein structure and LRR-RLK VIII-mediated signalling may be important mechanisms for toxicity and tolerance to As in the species. Here, we provide a comprehensive survey of global transcriptional regulation for As and identify stress- and tolerance-associated genes responding to As. PMID:24734953

  3. Over-Expression of ScMnSOD, a SOD Gene Derived from Jojoba, Improve Drought Tolerance in Arabidopsis

    Institute of Scientific and Technical Information of China (English)

    LIU Xiao-fei; ZHANG Gen-fa; SUN Wei-min; LI Ze-qin; BAI Rui-xue; LI Jing-xiao; SHI Zi-han; GENG Hong-wei; ZHENG Ying; ZHANG Jun

    2013-01-01

    Jojoba (Simmondsia chinensis) is mainly distributed in desert, and the molecular mechanisms of jojoba in response to abiotic stress still remain elusive. In this paper, we cloned and characterized a SOD gene from jojoba named as ScMnSOD, and introduced into Arabidopsis to investigate its functions of responding to drought stress. The transgenic Arabidopsis showed an improvement in drought tolerance. Moreover, under a water deifcit condition, the accumulation of reactive oxygen species (ROS) was remarkably decreased in the transgenic lines compared to the WT. Furthermore, the ScMnSOD promoter was cloned to the 5´-upstream of GUS coding region in a binary vector, and introduced into Arabidopsis. And results showed that ScMnSOD expression can be induced by drought, salt, ABA, and low temperature. In conclusion, ScMnSOD plays an important role in drought tolerance which is, at least partially, attributed to its role in ROS detoxiifcation.

  4. Anti-apoptotic response during anoxia and recovery in a freeze-tolerant wood frog (Rana sylvatica

    Directory of Open Access Journals (Sweden)

    Victoria E.M. Gerber

    2016-03-01

    Full Text Available The common wood frog, Rana sylvatica, utilizes freeze tolerance as a means of winter survival. Concealed beneath a layer of leaf litter and blanketed by snow, these frogs withstand subzero temperatures by allowing approximately 65–70% of total body water to freeze. Freezing is generally considered to be an ischemic event in which the blood oxygen supply is impeded and may lead to low levels of ATP production and exposure to oxidative stress. Therefore, it is as important to selectively upregulate cytoprotective mechanisms such as the heat shock protein (HSP response and expression of antioxidants as it is to shut down majority of ATP consuming processes in the cell. The objective of this study was to investigate another probable cytoprotective mechanism, anti-apoptosis during oxygen deprivation and recovery in the anoxia tolerant wood frog. In particular, relative protein expression levels of two important apoptotic regulator proteins, Bax and p-p53 (S46, and five anti-apoptotic/pro-survival proteins, Bcl-2, p-Bcl-2 (S70, Bcl-xL, x-IAP, and c-IAP in response to normoxic, 24 Hr anoxic exposure, and 4 Hr recovery stages were assessed in the liver and skeletal muscle using western immunoblotting. The results suggest a tissue-specific regulation of the anti-apoptotic pathway in the wood frog, where both liver and skeletal muscle shows an overall decrease in apoptosis and an increase in cell survival. This type of cytoprotective mechanism could be aimed at preserving the existing cellular components during long-term anoxia and oxygen recovery phases in the wood frog.

  5. Mechanisms of Salt Tolerance in Transgenic Arabidopsis thaliana Carrying a Peroxisomal Ascorbate Peroxidase Gene from Barley

    Institute of Scientific and Technical Information of China (English)

    XU Wei-Feng; SHI Wei-Ming; A. UEDA; T. TAKABE

    2008-01-01

    Ascorbate peroxidases (APX), localized in the cytosol, peroxisome, mitochondria, and chloroplasts of plant cells,catalyze the reduction of H2O2 to water by using ascorbic acid as the specific electron donor. To determine the role of peroxisomal type ascorbate peroxidasc (pAPX), an antioxidant enzyme, in protection against salt-induced oxidative stress, transgenic Arabidopsis thaliana plant carrying a pAPX gene (HvAPX1) from barley (Hordeum vulgare L.) was analyzed. The transgenic line pAPX3 was found to be more tolerant to salt stress than the wild type. Irrespective of salt stress, there were no significant differences in Na+, K+, Ca2+, and Mg2+ contents and the ratio of K+ to Na+ between pAPX3 and the wild type. Clearly, the salt tolerance in pAPX3 was not due to the maintenance and reestablishment of cellular ion homeostasis. However, the degree of H2O2 and lipid peroxidation (measured as the levels of malondialdehyde)accumulation under salt stress was higher in the wild type than in pAPX3. The mechanism of salt tolerance in transgenic pAPX3 can thus be explained by reduction of oxidative stress injury. Under all conditions tested, activities of superoxide,glutathionc reductase, and catalase were not significantly different between pAPX3 and the wild type. In contrast, the activity of APX was significantly higher in the transgcnic plant than in wild type under salt stress. These results suggested that in higher plants, HvAPX1 played an important role in salt tolerance and was a candidate gene for developing salt-tolerant crop plants.

  6. Ascorbate peroxidase from Jatropha curcas enhances salt tolerance in transgenic Arabidopsis.

    Science.gov (United States)

    Chen, Y; Cai, J; Yang, F X; Zhou, B; Zhou, L R

    2015-05-11

    Ascorbate peroxidase (APX) plays a central role in the ascorbate-glutathione cycle and is a key enzyme in cellular H2O2 me-tabolism. It includes a family of isoenzymes with different character-istics, which are identified in many higher plants. In the present study, we isolated the APX gene from Jatropha curcas L, which is similar with other previously characterized APXs as revealed by alignment and phylogenetic analysis of its deduced amino acid sequence. Real-time qPCR analysis showed that the expression level of JcAPX transcript significantly increased under NaCl stress. Subsequently, to elucidate the contribution of JcAPX to the protection against salt-induced oxi-dative stress, the expression construct p35S: JcAPX was created and transformed into Arabidopsis and transcribed. Under 150-mM NaCl stress, compared with wild type (WT), the overexpression of JcAPX in Arabidopsis increased the germination rate, the number of leaves, and the rosette area. In addition, the transgenic plants had longer roots, higher total chlorophyll content, higher total APX activity, and lower H2O2 content than the WT under NaCl stress conditions. These results suggested that higher APX activity in transgenic lines increases the salt tolerance by enhancing scavenging capacity for reactive oxygen spe-cies under NaCl stress conditions.

  7. Construction from a single parent of baker's yeast strains with high freeze tolerance and fermentative activity in both lean and sweet doughs.

    Science.gov (United States)

    Nakagawa, S; Ouchi, K

    1994-10-01

    From a freeze-tolerant baker's yeast (Saccharomyces cerevisiae), 2,333 spore clones were obtained. To improve the leavening ability in lean dough of the parent strain, we selected 555 of the high-maltose-fermentative spore clones by using a method in which a soft agar solution containing maltose and bromocresol purple was overlaid on yeast colonies. By measuring the gassing power in the dough, we selected 66 spore clones with a good leavening ability in lean dough and a total of 694 hybrids were constructed by crossing them. Among these hybrids, we obtained 50 novel freeze-tolerant strains with good leavening ability in all lean, regular, and sweet doughs comparable to that of commercial baker's yeast. Hybrids with improved leavening ability or freeze tolerance compared with the parent yeast and commercial baker's yeasts were also obtained. These results suggest that hybridization between spore clones derived from a single parent strain is effective for improving the properties of baker's yeasts.

  8. Is the OJIP Test a Reliable Indicator of Winter Hardiness and Freezing Tolerance of Common Wheat and Triticale under Variable Winter Environments?

    Science.gov (United States)

    Rapacz, Marcin; Sasal, Monika; Kalaji, Hazem M; Kościelniak, Janusz

    2015-01-01

    OJIP analysis, which explores changes in photosystem II (PSII) photochemical performance, has been used as a measure of plant susceptibility to stress. However, in the case of freezing tolerance and winter hardiness, which are highly environmentally variable, the use of this method can give ambiguous results depending on the species as well as the sampling year and time. To clarify this issue, we performed chlorophyll fluorescence measurements over three subsequent winters (2010/11, 2011/12 and 2012/13) on 220 accessions of common winter wheat and 139 accessions of winter triticale. After freezing, leaves were collected from cold-acclimated plants in the laboratory and field-grown plants. Observations of field survival in seven locations across Poland and measurements of freezing tolerance of the studied plants were also recorded. Our results confirm that the OJIP test is a reliable indicator of winter hardiness and freezing tolerance of common wheat and triticale under unstable winter environments. Regardless of species, the testing conditions giving the most reliable results were identical, and the reliability of the test could be easily checked by analysis of some relationships between OJIP-test parameters. We also found that triticale is more winter hardy and freezing tolerant than wheat. In addition, the two species were characterized by different patterns of photosynthetic apparatus acclimation to cold.

  9. The Arabidopsis RNA-Binding Protein AtRGGA Regulates Tolerance to Salt and Drought Stress

    KAUST Repository

    Ambrosone, Alfredo

    2015-03-17

    Salt and drought stress severely reduce plant growth and crop productivity worldwide. The identification of genes underlying stress response and tolerance is the subject of intense research in plant biology. Through microarray analyses, we previously identified in potato (Solanum tuberosum) StRGGA, coding for an Arginine Glycine Glycine (RGG) box-containing RNA-binding protein, whose expression was specifically induced in potato cell cultures gradually exposed to osmotic stress. Here, we show that the Arabidopsis (Arabidopsis thaliana) ortholog, AtRGGA, is a functional RNA-binding protein required for a proper response to osmotic stress. AtRGGA gene expression was up-regulated in seedlings after long-term exposure to abscisic acid (ABA) and polyethylene glycol, while treatments with NaCl resulted in AtRGGA down-regulation. AtRGGA promoter analysis showed activity in several tissues, including stomata, the organs controlling transpiration. Fusion of AtRGGA with yellow fluorescent protein indicated that AtRGGA is localized in the cytoplasm and the cytoplasmic perinuclear region. In addition, the rgga knockout mutant was hypersensitive to ABA in root growth and survival tests and to salt stress during germination and at the vegetative stage. AtRGGA-overexpressing plants showed higher tolerance to ABA and salt stress on plates and in soil, accumulating lower levels of proline when exposed to drought stress. Finally, a global analysis of gene expression revealed extensive alterations in the transcriptome under salt stress, including several genes such as ASCORBATE PEROXIDASE2, GLUTATHIONE S-TRANSFERASE TAU9, and several SMALL AUXIN UPREGULATED RNA-like genes showing opposite expression behavior in transgenic and knockout plants. Taken together, our results reveal an important role of AtRGGA in the mechanisms of plant response and adaptation to stress.

  10. The Vacuolar Manganese Transporter MTP8 Determines Tolerance to Iron Deficiency-Induced Chlorosis in Arabidopsis.

    Science.gov (United States)

    Eroglu, Seckin; Meier, Bastian; von Wirén, Nicolaus; Peiter, Edgar

    2016-02-01

    Iron (Fe) deficiency is a widespread nutritional disorder on calcareous soils. To identify genes involved in the Fe deficiency response, Arabidopsis (Arabidopsis thaliana) transfer DNA insertion lines were screened on a high-pH medium with low Fe availability. This approach identified METAL TOLERANCE PROTEIN8 (MTP8), a member of the Cation Diffusion Facilitator family, as a critical determinant for the tolerance to Fe deficiency-induced chlorosis, also on soil substrate. Subcellular localization to the tonoplast, complementation of a manganese (Mn)-sensitive Saccharomyces cerevisiae yeast strain, and Mn sensitivity of mtp8 knockout mutants characterized the protein as a vacuolar Mn transporter suitable to prevent plant cells from Mn toxicity. MTP8 expression was strongly induced on low-Fe as well as high-Mn medium, which were both strictly dependent on the transcription factor FIT, indicating that high-Mn stress induces Fe deficiency. mtp8 mutants were only hypersensitive to Fe deficiency when Mn was present in the medium, which further suggested an Mn-specific role of MTP8 during Fe limitation. Under those conditions, mtp8 mutants not only translocated more Mn to the shoot than did wild-type plants but suffered in particular from critically low Fe concentrations and, hence, Fe chlorosis, although the transcriptional Fe deficiency response was up-regulated more strongly in mtp8. The diminished uptake of Fe from Mn-containing low-Fe medium by mtp8 mutants was caused by an impaired ability to boost the ferric chelate reductase activity, which is an essential process in Fe acquisition. These findings provide a mechanistic explanation for the long-known interference of Mn in Fe nutrition and define the molecular processes by which plants alleviate this antagonism.

  11. Overexpression of ARGOS Genes Modifies Plant Sensitivity to Ethylene, Leading to Improved Drought Tolerance in Both Arabidopsis and Maize.

    Science.gov (United States)

    Shi, Jinrui; Habben, Jeffrey E; Archibald, Rayeann L; Drummond, Bruce J; Chamberlin, Mark A; Williams, Robert W; Lafitte, H Renee; Weers, Ben P

    2015-09-01

    Lack of sufficient water is a major limiting factor to crop production worldwide, and the development of drought-tolerant germplasm is needed to improve crop productivity. The phytohormone ethylene modulates plant growth and development as well as plant response to abiotic stress. Recent research has shown that modifying ethylene biosynthesis and signaling can enhance plant drought tolerance. Here, we report novel negative regulators of ethylene signal transduction in Arabidopsis (Arabidopsis thaliana) and maize (Zea mays). These regulators are encoded by the ARGOS gene family. In Arabidopsis, overexpression of maize ARGOS1 (ZmARGOS1), ZmARGOS8, Arabidopsis ARGOS homolog ORGAN SIZE RELATED1 (AtOSR1), and AtOSR2 reduced plant sensitivity to ethylene, leading to enhanced drought tolerance. RNA profiling and genetic analysis suggested that the ZmARGOS1 transgene acts between an ethylene receptor and CONSTITUTIVE TRIPLE RESPONSE1 in the ethylene signaling pathway, affecting ethylene perception or the early stages of ethylene signaling. Overexpressed ZmARGOS1 is localized to the endoplasmic reticulum and Golgi membrane, where the ethylene receptors and the ethylene signaling protein ETHYLENE-INSENSITIVE2 and REVERSION-TO-ETHYLENE SENSITIVITY1 reside. In transgenic maize plants, overexpression of ARGOS genes also reduces ethylene sensitivity. Moreover, field testing showed that UBIQUITIN1:ZmARGOS8 maize events had a greater grain yield than nontransgenic controls under both drought stress and well-watered conditions.

  12. Freezing tolerance and the histology of recovering nodes in St. Augustinegrass

    Science.gov (United States)

    St. Augustinegrass [Stenataphrum secundatum (Walt.) Kuntze] is a coarse-textured turfgrass commonly utilized for its excellent shade tolerance. However, inferior cold tolerance in comparison to other warm-season grasses limits its range primarily to the southeastern U. S., The objectives of this stu...

  13. Identification of a retroelement from the resurrection plant Boea hygrometrica that confers osmotic and alkaline tolerance in Arabidopsis thaliana.

    Directory of Open Access Journals (Sweden)

    Yan Zhao

    Full Text Available Functional genomic elements, including transposable elements, small RNAs and non-coding RNAs, are involved in regulation of gene expression in response to plant stress. To identify genomic elements that regulate dehydration and alkaline tolerance in Boea hygrometrica, a resurrection plant that inhabits drought and alkaline Karst areas, a genomic DNA library from B. hygrometrica was constructed and subsequently transformed into Arabidopsis using binary bacterial artificial chromosome (BIBAC vectors. Transgenic lines were screened under osmotic and alkaline conditions, leading to the identification of Clone L1-4 that conferred osmotic and alkaline tolerance. Sequence analyses revealed that L1-4 contained a 49-kb retroelement fragment from B. hygrometrica, of which only a truncated sequence was present in L1-4 transgenic Arabidopsis plants. Additional subcloning revealed that activity resided in a 2-kb sequence, designated Osmotic and Alkaline Resistance 1 (OAR1. In addition, transgenic Arabidopsis lines carrying an OAR1-homologue also showed similar stress tolerance phenotypes. Physiological and molecular analyses demonstrated that OAR1-transgenic plants exhibited improved photochemical efficiency and membrane integrity and biomarker gene expression under both osmotic and alkaline stresses. Short transcripts that originated from OAR1 were increased under stress conditions in both B. hygrometrica and Arabidopsis carrying OAR1. The relative copy number of OAR1 was stable in transgenic Arabidopsis under stress but increased in B. hygrometrica. Taken together, our results indicated a potential role of OAR1 element in plant tolerance to osmotic and alkaline stresses, and verified the feasibility of the BIBAC transformation technique to identify functional genomic elements from physiological model species.

  14. Differential remodeling of the lipidome during cold acclimation in natural accessions of Arabidopsis thaliana.

    Science.gov (United States)

    Degenkolbe, Thomas; Giavalisco, Patrick; Zuther, Ellen; Seiwert, Bettina; Hincha, Dirk K; Willmitzer, Lothar

    2012-12-01

    Freezing injury is a major factor limiting the geographical distribution of plant species and the growth and yield of crop plants. Plants from temperate climates are able to increase their freezing tolerance during exposure to low but non-freezing temperatures in a process termed cold acclimation. Damage to cellular membranes is the major cause of freezing injury in plants, and membrane lipid composition is strongly modified during cold acclimation. Forward and reverse genetic approaches have been used to probe the role of specific lipid-modifying enzymes in the freezing tolerance of plants. In the present paper we describe an alternative ecological genomics approach that relies on the natural genetic variation within a species. Arabidopsis thaliana has a wide geographical range throughout the Northern Hemisphere with significant natural variation in freezing tolerance that was used for a comparative analysis of the lipidomes of 15 Arabidopsis accessions using ultra-performance liquid chromatography coupled to Fourier-transform mass spectrometry, allowing the detection of 180 lipid species. After 14 days of cold acclimation at 4°C the plants from most accessions had accumulated massive amounts of storage lipids, with most of the changes in long-chain unsaturated triacylglycerides, while the total amount of membrane lipids was only slightly changed. Nevertheless, major changes in the relative amounts of different membrane lipids were also evident. The relative abundance of several lipid species was highly correlated with the freezing tolerance of the accessions, allowing the identification of possible marker lipids for plant freezing tolerance.

  15. Enhanced freeze tolerance of baker's yeast by overexpressed trehalose-6-phosphate synthase gene (TPS1) and deleted trehalase genes in frozen dough.

    Science.gov (United States)

    Tan, Haigang; Dong, Jian; Wang, Guanglu; Xu, Haiyan; Zhang, Cuiying; Xiao, Dongguang

    2014-08-01

    Several recombinant strains with overexpressed trehalose-6-phosphate synthase gene (TPS1) and/or deleted trehalase genes were obtained to elucidate the relationships between TPS1, trehalase genes, content of intracellular trehalose and freeze tolerance of baker's yeast, as well as improve the fermentation properties of lean dough after freezing. In this study, strain TL301(TPS1) overexpressing TPS1 showed 62.92 % higher trehalose-6-phosphate synthase (Tps1) activity and enhanced the content of intracellular trehalose than the parental strain. Deleting ATH1 exerted a significant effect on trehalase activities and the degradation amount of intracellular trehalose during the first 30 min of prefermentation. This finding indicates that acid trehalase (Ath1) plays a role in intracellular trehalose degradation. NTH2 encodes a functional neutral trehalase (Nth2) that was significantly involved in intracellular trehalose degradation in the absence of the NTH1 and/or ATH1 gene. The survival ratio, freeze-tolerance ratio and relative fermentation ability of strain TL301(TPS1) were approximately twice as high as those of the parental strain (BY6-9α). The increase in freeze tolerance of strain TL301(TPS1) was accompanied by relatively low trehalase activity, high Tps1 activity and high residual content of intracellular trehalose. Our results suggest that overexpressing TPS1 and deleting trehalase genes are sufficient to improve the freeze tolerance of baker's yeast in frozen dough. The present study provides guidance for the commercial baking industry as well as the research on the intracellular trehalose mobilization and freeze tolerance of baker's yeast.

  16. Hydrogen sulfide regulates abiotic stress tolerance and biotic stress resistance in Arabidopsis

    Institute of Scientific and Technical Information of China (English)

    Haitao Shi; Tiantian Ye; Ning Han; Hongwu Bian; Xiaodong Liu; Zhulong Chan

    2015-01-01

    Hydrogen sulfide (H2S) is an important gaseous molecule in various plant developmental processes and plant stress responses. In this study, the transgenic Arabidopsis thaliana plants with modulated expressions of two cysteine desulfhydrases, and exogenous H2S donor (sodium hydrosulfide, NaHS) and H2S scavenger (hypotaurine, HT) pre-treated plants were used to dissect the involvement of H2S in plant stress responses. The cysteine desulfhydrases overexpressing plants and NaHS pre-treated plants exhibited higher endogenous H2S level and improved abiotic stress tolerance and biotic stress resistance, while cysteine desulfhydrases knockdown plants and HT pre-treated plants displayed lower endogenous H2S level and decreased stress resistance. Moreover, H2S upregulated the transcripts of multiple abiotic and biotic stress-related genes, and inhibited reactive oxygen species (ROS) accumulation. Interest-ingly, MIR393-mediated auxin signaling including MIR393a/b and their target genes (TIR1, AFB1, AFB2, and AFB3) was transcrip-tional y regulated by H2S, and was related with H2S-induced antibacterial resistance. Moreover, H2S regulated 50 carbon metabolites including amino acids, organic acids, sugars, sugar alcohols, and aromatic amines. Taken together, these results indicated that cysteine desulfhydrase and H2S conferred abiotic stress tolerance and biotic stress resistance, via affecting the stress-related gene expressions, ROS metabolism, metabolic homeostasis, and MIR393-targeted auxin receptors.

  17. Overexpression of Arabidopsis molybdenum cofactor sulfurase gene confers drought tolerance in maize (Zea mays L.).

    Science.gov (United States)

    Lu, Yao; Li, Yajun; Zhang, Jiachang; Xiao, Yitao; Yue, Yuesen; Duan, Liusheng; Zhang, Mingcai; Li, Zhaohu

    2013-01-01

    Abscisic acid (ABA) is a key component of the signaling system that integrates plant adaptive responses to abiotic stress. Overexpression of Arabidopsis molybdenum cofactor sulfurase gene (LOS5) in maize markedly enhanced the expression of ZmAO and aldehyde oxidase (AO) activity, leading to ABA accumulation and increased drought tolerance. Transgenic maize (Zea mays L.) exhibited the expected reductions in stomatal aperture, which led to decreased water loss and maintenance of higher relative water content (RWC) and leaf water potential. Also, transgenic maize subjected to drought treatment exhibited lower leaf wilting, electrolyte leakage, malondialdehyde (MDA) and H(2)O(2) content, and higher activities of antioxidative enzymes and proline content compared to wild-type (WT) maize. Moreover, overexpression of LOS5 enhanced the expression of stress-regulated genes such as Rad 17, NCED1, CAT1, and ZmP5CS1 under drought stress conditions, and increased root system development and biomass yield after re-watering. The increased drought tolerance in transgenic plants was associated with ABA accumulation via activated AO and expression of stress-related gene via ABA induction, which sequentially induced a set of favorable stress-related physiological and biochemical responses.

  18. Arabidopsis LOS5 Gene Enhances Chilling and Salt Stress Tolerance in Cucumber

    Institute of Scientific and Technical Information of China (English)

    LIU Li-ying; DUAN Liu-sheng; ZHANG Jia-chang; MI Guo-quan; ZHANG Xiao-lan; ZHANG Zhen-xian; REN Hua-zhong

    2013-01-01

    Low temperature and high salinity are the major abiotic stresses that restrict cucumber growth and production, breeding materials with multiple abiotic resistance are in greatly need. Here we investigated the effect of introducing the LOS5 gene, a key regulator of ABA biosynthesis in Arabidopsis thaliana, under the stress-responsive RD29A promoter into cucumber (Cucumis sativus L. cv. S516). We found that T1 RD29A-LOS5 transgenic lines have enhanced tolerance to cold and salt stresses. Specifically, transgenic lines exhibited dwarf phenotypes with reduced leaf number, shorter internode, decreased length of the biggest leaf, fewer female flowers, shorter fruit neck and lower vitamin C (Vc). The increased cold tolerance can be reflected from the significantly decreased cold index, the reduced electrolyte leakage index and the MDA content upon cold treatment as compared to those in the control. This may result from the accumulation of internal ABA, soluble sugars and proline, and the enhanced activities of protective enzymes superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in the transgenic lines. Under salt treatment, the transgenic lines exhibited increased germination index, vigor index, more lateral roots and increased root fresh weight. Moreover, RD29A-LOS5 transgenic plants displayed quicker responses in salt stress than that in low-temperature stress.

  19. Host responses in life-history traits and tolerance to virus infection in Arabidopsis thaliana.

    Directory of Open Access Journals (Sweden)

    Israel Pagán

    Full Text Available Knowing how hosts respond to parasite infection is paramount in understanding the effects of parasites on host populations and hence host-parasite co-evolution. Modification of life-history traits in response to parasitism has received less attention than other defence strategies. Life-history theory predicts that parasitised hosts will increase reproductive effort and accelerate reproduction. However, empirical analyses of these predictions are few and mostly limited to animal-parasite systems. We have analysed life-history trait responses in 18 accessions of Arabidopsis thaliana infected at two different developmental stages with three strains of Cucumber mosaic virus (CMV. Accessions were divided into two groups according to allometric relationships; these groups differed also in their tolerance to CMV infection. Life-history trait modification upon virus infection depended on the host genotype and the stage at infection. While all accessions delayed flowering, only the more tolerant allometric group modified resource allocation to increase the production of reproductive structures and progeny, and reduced the length of reproductive period. Our results are in agreement with modifications of life-history traits reported for parasitised animals and with predictions from life-history theory. Thus, we provide empirical support for the general validity of theoretical predictions. In addition, this experimental approach allowed us to quantitatively estimate the genetic determinism of life-history trait plasticity and to evaluate the role of life-history trait modification in defence against parasites, two largely unexplored issues.

  20. Prefoldins 3 and 5 Play an Essential Role in Arabidopsis Tolerance to Salt Stress

    Institute of Scientific and Technical Information of China (English)

    Miguel A.Rodriguez-Milla; Julio Salinas

    2009-01-01

    During the last years,our understanding of the mechanisms that control plant response to salt stress has been steadily progressing.Pharmacological studies have allowed the suggestion that the cytoskeleton may be involved in reg-ulating such a response.Nevertheless,genetic evidence establishing that the cytoskeleton has a role in plant tolerance to salt stress has not been reported yet.Here,we have characterized Arabidopsis T-DNA mutants for genes encoding proteins orthologous to prefoldin (PFD) subunits 3 and 5 from yeast and mammals.In these organisms,PFD subunits,also known as Genes Involved in Microtubule biogenesis (GIM),form a heterohexameric PFD complex implicated in tubulin and actin folding.We show that,indeed,PFD3 and PFD5 can substitute for the loss of their yeast orthologs,as they are able to complement yeast gim2△ and gim5△ mutants,respectively.Our results indicate thatpfd3 and pfd5 mutants have reduced levels of α- and β-tubulin compared to the wild-type plants when growing under both control and salt-stress conditions.In addition,pfd3 and pfd5 mutants display alterations in their developmental patterns and microtubule organization,and,more importantly,are hypersensitive to high concentrations of NaCI but not of LiCI or mannitol.These results demonstrate that the cytoskeleton plays an essential role in plant tolerance to salt stress.

  1. Hydrogen sulfide regulates abiotic stress tolerance and biotic stress resistance in Arabidopsis.

    Science.gov (United States)

    Shi, Haitao; Ye, Tiantian; Han, Ning; Bian, Hongwu; Liu, Xiaodong; Chan, Zhulong

    2015-07-01

    Hydrogen sulfide (H2S) is an important gaseous molecule in various plant developmental processes and plant stress responses. In this study, the transgenic Arabidopsis thaliana plants with modulated expressions of two cysteine desulfhydrases, and exogenous H2S donor (sodium hydrosulfide, NaHS) and H2S scavenger (hypotaurine, HT) pre-treated plants were used to dissect the involvement of H2S in plant stress responses. The cysteine desulfhydrases overexpressing plants and NaHS pre-treated plants exhibited higher endogenous H2S level and improved abiotic stress tolerance and biotic stress resistance, while cysteine desulfhydrases knockdown plants and HT pre-treated plants displayed lower endogenous H2S level and decreased stress resistance. Moreover, H2S upregulated the transcripts of multiple abiotic and biotic stress-related genes, and inhibited reactive oxygen species (ROS) accumulation. Interestingly, MIR393-mediated auxin signaling including MIR393a/b and their target genes (TIR1, AFB1, AFB2, and AFB3) was transcriptionally regulated by H2S, and was related with H2S-induced antibacterial resistance. Moreover, H2S regulated 50 carbon metabolites including amino acids, organic acids, sugars, sugar alcohols, and aromatic amines. Taken together, these results indicated that cysteine desulfhydrase and H2S conferred abiotic stress tolerance and biotic stress resistance, via affecting the stress-related gene expressions, ROS metabolism, metabolic homeostasis, and MIR393-targeted auxin receptors.

  2. Transcriptome Analysis of Induced Systemic Drought Tolerance Elicited by Pseudomonas chlororaphis O6 in Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Song-Mi Cho

    2013-06-01

    Full Text Available Root colonization by Pseudomonas chlororaphis O6 induces systemic drought tolerance in Arabidopsis thaliana. Microarray analysis was performed using the 22,800-gene Affymetrix GeneChips to identify differentially-expressed genes from plants colonized with or without P. chlororaphis O6 under drought stressed conditions or normal growth conditions. Root colonization in plants grown under regular irrigation condition increased transcript accumulation from genes associated with defense, response to reactive oxygen species, and auxin- and jasmonic acid-responsive genes, but decreased transcription factors associated with ethylene and abscisic acid signaling. The cluster of genes involved in plant disease resistance were up-regulated, but the set of drought signaling response genes were down-regulated in the P. chlororaphis O6-colonized under drought stress plants compared to those of the drought stressed plants without bacterial treatment. Transcripts of the jasmonic acid-marker genes, VSP1 and pdf-1.2, the salicylic acid regulated gene, PR-1, and the ethylene-response gene, HEL, also were up-regulated in plants colonized by P. chlororaphis O6, but differed in their responsiveness to drought stress. These data show how gene expression in plants lacking adequate water can be remarkably influenced by microbial colonization leading to plant protection, and the activation of the plant defense signal pathway induced by root colonization of P. chlororaphis O6 might be a key element for induced systemic tolerance by microbes.

  3. Does acute lead (Pb) contamination influence membrane fatty acid composition and freeze tolerance in intertidal blue mussels in arctic Greenland?

    Science.gov (United States)

    Thyrring, Jakob; Juhl, Bodil Klein; Holmstrup, Martin; Blicher, Martin E; Sejr, Mikael K

    2015-11-01

    In their natural habitats, organisms are exposed to multiple stressors. Heavy metal contamination stresses the cell membrane due to increased peroxidation of lipids. Likewise, sub-zero air temperatures potentially reduce membrane functionality in ectothermal animals. We tested if acute lead (Pb) exposure for 7 days would influence survival in intertidal blue mussels (Mytilus edulis) after exposure to realistic sub-zero air temperatures. A full factorial experiment with five tissue Pb concentrations between 0 and 3500 μg Pb/g and six sub-zero temperatures from 0 to -17 °C were used to test the hypothesis that sub-lethal effects of Pb may increase the lethality caused by freezing in blue mussels exposed to temperatures simulating Greenland winter conditions. We found a significant effect of temperature on mortality. However, the short-term exposure to Pb did not result in any effects of Pb, nor did we find interactions between Pb and temperature. We analysed the relative abundance of major phospholipid fatty acids (PLFAs) in the gill tissue, but we found no significant effect of Pb tissue concentration on PLFA composition. Results suggest that Pb accumulation has limited effects on freeze tolerance and does not induce membrane damage in terms of persistent lipid peroxidation.

  4. Differential tolerance to direct and indirect density-dependent costs of viral infection in Arabidopsis thaliana.

    Directory of Open Access Journals (Sweden)

    Israel Pagán

    2009-07-01

    Full Text Available Population density and costs of parasite infection may condition the capacity of organisms to grow, survive and reproduce, i.e. their competitive ability. In host-parasite systems there are different competitive interactions: among uninfected hosts, among infected hosts, and between uninfected and infected hosts. Consequently, parasite infection results in a direct cost, due to parasitism itself, and in an indirect cost, due to modification of the competitive ability of the infected host. Theory predicts that host fitness reduction will be higher under the combined effects of costs of parasitism and competition than under each factor separately. However, experimental support for this prediction is scarce, and derives mostly from animal-parasite systems. We have analysed the interaction between parasite infection and plant density using the plant-parasite system of Arabidopsis thaliana and the generalist virus Cucumber mosaic virus (CMV. Plants of three wild genotypes grown at different densities were infected by CMV at various prevalences, and the effects of infection on plant growth and reproduction were quantified. Results demonstrate that the combined effects of host density and parasite infection may result either in a reduction or in an increase of the competitive ability of the host. The two genotypes investing a higher proportion of resources to reproduction showed tolerance to the direct cost of infection, while the genotype investing a higher proportion of resources to growth showed tolerance to the indirect cost of infection. Our findings show that the outcome of the interaction between host density and parasitism depends on the host genotype, which determines the plasticity of life-history traits and consequently, the host capacity to develop different tolerance mechanisms to the direct or indirect costs of parasitism. These results indicate the high relevance of host density and parasitism in determining the competitive ability of a

  5. An Arabidopsis mitochondrial uncoupling protein confers tolerance to drought and salt stress in transgenic tobacco plants.

    Directory of Open Access Journals (Sweden)

    Kevin Begcy

    Full Text Available BACKGROUND: Plants are challenged by a large number of environmental stresses that reduce productivity and even cause death. Both chloroplasts and mitochondria produce reactive oxygen species under normal conditions; however, stress causes an imbalance in these species that leads to deviations from normal cellular conditions and a variety of toxic effects. Mitochondria have uncoupling proteins (UCPs that uncouple electron transport from ATP synthesis. There is evidence that UCPs play a role in alleviating stress caused by reactive oxygen species overproduction. However, direct evidence that UCPs protect plants from abiotic stress is lacking. METHODOLOGY/PRINCIPAL FINDINGS: Tolerances to salt and water deficit were analyzed in transgenic tobacco plants that overexpress a UCP (AtUCP1 from Arabidopsis thaliana. Seeds of AtUCP1 transgenic lines germinated faster, and adult plants showed better responses to drought and salt stress than wild-type (WT plants. These phenotypes correlated with increased water retention and higher gas exchange parameters in transgenic plants that overexpress AtUCP1. WT plants exhibited increased respiration under stress, while transgenic plants were only slightly affected. Furthermore, the transgenic plants showed reduced accumulation of hydrogen peroxide in stressed leaves compared with WT plants. CONCLUSIONS/SIGNIFICANCE: Higher levels of AtUCP1 improved tolerance to multiple abiotic stresses, and this protection was correlated with lower oxidative stress. Our data support previous assumptions that UCPs reduce the imbalance of reactive oxygen species. Our data also suggest that UCPs may play a role in stomatal closure, which agrees with other evidence of a direct relationship between these proteins and photosynthesis. Manipulation of the UCP protein expression in mitochondria is a new avenue for crop improvement and may lead to crops with greater tolerance for challenging environmental conditions.

  6. The Opuntia streptacantha OpsHSP18 Gene Confers Salt and Osmotic Stress Tolerance in Arabidopsis thaliana

    Science.gov (United States)

    Salas-Muñoz, Silvia; Gómez-Anduro, Gracia; Delgado-Sánchez, Pablo; Rodríguez-Kessler, Margarita; Jiménez-Bremont, Juan Francisco

    2012-01-01

    Abiotic stress limits seed germination, plant growth, flowering and fruit quality, causing economic decrease. Small Heat Shock Proteins (sHSPs) are chaperons with roles in stress tolerance. Herein, we report the functional characterization of a cytosolic class CI sHSP (OpsHSP18) from Opuntia streptacantha during seed germination in Arabidopsis thaliana transgenic lines subjected to different stress and hormone treatments. The over-expression of the OpsHSP18 gene in A. thaliana increased the seed germination rate under salt (NaCl) and osmotic (glucose and mannitol) stress, and in ABA treatments, compared with WT. On the other hand, the over-expression of the OpsHSP18 gene enhanced tolerance to salt (150 mM NaCl) and osmotic (274 mM mannitol) stress in Arabidopsis seedlings treated during 14 and 21 days, respectively. These plants showed increased survival rates (52.00 and 73.33%, respectively) with respect to the WT (18.75 and 53.75%, respectively). Thus, our results show that OpsHSP18 gene might have an important role in abiotic stress tolerance, in particular in seed germination and survival rate of Arabidopsis plants under unfavorable conditions. PMID:22949853

  7. Overproduction of the membrane-bound receptor-like protein kinase 1, RPK1, enhances abiotic stress tolerance in Arabidopsis.

    Science.gov (United States)

    Osakabe, Yuriko; Mizuno, Shinji; Tanaka, Hidenori; Maruyama, Kyonoshin; Osakabe, Keishi; Todaka, Daisuke; Fujita, Yasunari; Kobayashi, Masatomo; Shinozaki, Kazuo; Yamaguchi-Shinozaki, Kazuko

    2010-03-19

    RPK1 (receptor-like protein kinase 1) localizes to the plasma membrane and functions as a regulator of abscisic acid (ABA) signaling in Arabidopsis. In our current study, we investigated the effect of RPK1 disruption and overproduction upon plant responses to drought stress. Transgenic Arabidopsis overexpressing the RPK1 protein showed increased ABA sensitivity in their root growth and stomatal closure and also displayed less transpirational water loss. In contrast, a mutant lacking RPK1 function, rpk1-1, was found to be resistant to ABA during these processes and showed increased water loss. RPK1 overproduction in these transgenic plants thus increased their tolerance to drought stress. We performed microarray analysis of RPK1 transgenic plants and observed enhanced expression of several stress-responsive genes, such as Cor15a, Cor15b, and rd29A, in addition to H(2)O(2)-responsive genes. Consistently, the expression levels of ABA/stress-responsive genes in rpk1-1 had decreased compared with wild type. The results suggest that the overproduction of RPK1 enhances both the ABA and drought stress signaling pathways. Furthermore, the leaves of the rpk1-1 plants exhibit higher sensitivity to oxidative stress upon ABA-pretreatment, whereas transgenic plants overproducing RPK1 manifest increased tolerance to this stress. Our current data suggest therefore that RPK1 overproduction controls reactive oxygen species homeostasis and enhances both water and oxidative stress tolerance in Arabidopsis.

  8. SUMO E3 Ligase AtMMS21 Regulates Drought Tolerance in Arabidopsis thaliana

    Institute of Scientific and Technical Information of China (English)

    Shengchun Zhang; Yanli Qi; Ming Liu; ChengweiYang

    2013-01-01

    Post-translational modifications of proteins by small ubiquitin-like modifiers (SUMOs) play crucial roles in plant growth and development,and in stress responses.The MMS21 is a newly-identified Arabidopsis thaliana L.SUMO E3 ligase gene aside from the SIZ1,and its function requires further elucidation.Here,we show that MMS21 deficient plants display improved drought tolerance,and constitutive expression of MMS21 reduces drought tolerance.The expression of MMS21 was reduced by abscisic acid (ABA),polyethylene glycol (PEG) or drought stress.Under drought conditions,mms21 mutants showed the highest survival rate and the slowest water loss,and accumulated a higher level of free proline compared to wild-type (WT) and MMS21 over-expression plants.Stomatal aperture,seed germination and cotyledon greening analysis indicated that mms21 was hypersensitive to ABA.Molecular genetic analysis revealed that MMS21 deficiency led to elevated expression of a series of ABA-mediated stress-responsive genes,including COR15A,RD22,and P5CS1 The ABA and drought-induced stress-responsive genes,including RAB18,RD29A and RD29B,were inhibited by constitutive expression of MMS21.Moreover,ABA-induced accumulation of SUMO-protein conjugates was blocked in the mms21 mutant.We thus conclude that MMS21 plays a role in the drought stress response,likely through regulation of gene expression in an ABA-dependent pathway.

  9. Arsenic tolerance in Arabidopsis is mediated by two ABCC-type phytochelatin transporters.

    Science.gov (United States)

    Song, Won-Yong; Park, Jiyoung; Mendoza-Cózatl, David G; Suter-Grotemeyer, Marianne; Shim, Donghwan; Hörtensteiner, Stefan; Geisler, Markus; Weder, Barbara; Rea, Philip A; Rentsch, Doris; Schroeder, Julian I; Lee, Youngsook; Martinoia, Enrico

    2010-12-01

    Arsenic is an extremely toxic metalloid causing serious health problems. In Southeast Asia, aquifers providing drinking and agricultural water for tens of millions of people are contaminated with arsenic. To reduce nutritional arsenic intake through the consumption of contaminated plants, identification of the mechanisms for arsenic accumulation and detoxification in plants is a prerequisite. Phytochelatins (PCs) are glutathione-derived peptides that chelate heavy metals and metalloids such as arsenic, thereby functioning as the first step in their detoxification. Plant vacuoles act as final detoxification stores for heavy metals and arsenic. The essential PC-metal(loid) transporters that sequester toxic metal(loid)s in plant vacuoles have long been sought but remain unidentified in plants. Here we show that in the absence of two ABCC-type transporters, AtABCC1 and AtABCC2, Arabidopsis thaliana is extremely sensitive to arsenic and arsenic-based herbicides. Heterologous expression of these ABCC transporters in phytochelatin-producing Saccharomyces cerevisiae enhanced arsenic tolerance and accumulation. Furthermore, membrane vesicles isolated from these yeasts exhibited a pronounced arsenite [As(III)]-PC(2) transport activity. Vacuoles isolated from atabcc1 atabcc2 double knockout plants exhibited a very low residual As(III)-PC(2) transport activity, and interestingly, less PC was produced in mutant plants when exposed to arsenic. Overexpression of AtPCS1 and AtABCC1 resulted in plants exhibiting increased arsenic tolerance. Our findings demonstrate that AtABCC1 and AtABCC2 are the long-sought and major vacuolar PC transporters. Modulation of vacuolar PC transporters in other plants may allow engineering of plants suited either for phytoremediation or reduced accumulation of arsenic in edible organs.

  10. The role of glutathione in mercury tolerance resembles its function under cadmium stress in Arabidopsis.

    Science.gov (United States)

    Sobrino-Plata, Juan; Carrasco-Gil, Sandra; Abadía, Javier; Escobar, Carolina; Álvarez-Fernández, Ana; Hernández, Luis E

    2014-02-01

    Recent research efforts have highlighted the importance of glutathione (GSH) as a key antioxidant metabolite for metal tolerance in plants. Little is known about the mechanisms involved in stress due to mercury (Hg), one of the most hazardous metals to the environment and human health. To understand the implication of GSH metabolism for Hg tolerance, we used two γ-glutamylcysteine synthetase (γECS) Arabidopsis thaliana allele mutants (rax1-1 and cad2-1) and a phytochelatin synthase (PCS) mutant (cad1-3). The leaves of these mutants and of wild type (Col-0) were infiltrated with a solution containing Cd or Hg (0, 3 and 30 μM) and incubated for 24 and 48 h. The formation of phytochelatins (PCs) in the leaf extracts was followed by two different HPLC-based methods and occurred in Col-0, cad2-1 and rax1-1 plants exposed to Cd, whereas in the Hg treatments, PCs accumulated mainly in Col-0 and rax1-1, where Hg-PC complexes were also detected. ASA and GSH/GSSG levels increased under moderate metal stress conditions, accompanied by increased GSH reductase (GR) activity and expression. However, higher metal doses led to a decrease in the analysed parameters, and stronger toxic effects appeared with 30 μM Hg. The GSH concentration was significantly higher in rax1-1 (70% of Col-0) than in cad2-1 (40% of Col-0). The leaves of rax1-1 were less sensitive than cad2-1, in accordance with the greater expression of γECS in rax1-1. Our results underline the existence of a minimal GSH concentration threshold needed to minimise the toxic effects exerted by Hg.

  11. The RdDM Pathway Is Required for Basal Heat Tolerance in Arabidopsis

    Institute of Scientific and Technical Information of China (English)

    Olga V.Popova; Huy Q.Dinh; Werner Aufsatz; Claudia Jonak

    2013-01-01

    Heat stress affects epigenetic gene silencing in Arabidopsis.To test for a mechanistic involvement of epigenetic regulation in heat-stress responses,we analyzed the heat tolerance of mutants defective in DNA methylation,histone modifications,chromatin-remodeling,or siRNA-based silencing pathways.Plants deficient in NRPD2,the common second-largest subunit of RNA polymerases Ⅳ and V,and in the Rpd3-type histone deacetylase HDA6 were hypersensitive to heat exposure.Microarray analysis demonstrated that NRPD2 and HDA6 have independent roles in transcriptional reprogramming in response to temperature stress.The misexpression of protein-coding genes in nrpd2 mutants recovering from heat correlated with defective epigenetic regulation of adjacent transposon remnants which involved the loss of control of heat-stress-induced read-through transcription.We provide evidence that the transcriptional response to temperature stress,at least partially,relies on the integrity of the RNA-dependent DNA methylation pathway.

  12. Overexpression of Arabidopsis and rice stress genes' inducible transcription factor confers drought and salinity tolerance to rice.

    Science.gov (United States)

    Datta, Karabi; Baisakh, Niranjan; Ganguly, Moumita; Krishnan, Sellapan; Yamaguchi Shinozaki, Kazuko; Datta, Swapan K

    2012-06-01

    Rice yield is greatly affected by environmental stresses such as drought and salinity. In response to the challenge of producing rice plants tolerant to these stresses, we introduced cDNA encoding the transcription factors DREB1A and DREB1B under the control of the stress inducible rd29 promoter. Two different indica rice cultivars were used, BR29, an improved commercially cultivated variety from Bangladesh and IR68899B, an IRRI bred maintainer line for hybrid rice. Agrobacterium mediated transformation of BR29 was done independently with DREB1A isolated from rice and Arabidopsis and DREB1B isolated from rice, whereas biolistic transformation was done with rice- DREB1B in the case of IR68899B. Initial genetic integration was confirmed by PCR and Southern blot analysis. Salinity tolerance was assayed in very young seedlings. Drought stress tests were found to be more reliable when they were carried out at the pre-flowering booting stage. RNA gel blot analysis as well as quantitative PCR analysis was performed to estimate the transcription level under stressed and unstressed conditions. Agronomic performance studies were done with stressed and unstressed plants to compare the yield losses due to dehydration and salt loading stresses. Noticeably enhanced tolerance to dehydration was observed in the plants transformed with DREB1A isolated from Arabidopsis while DREB1B was found to be more effective for salt tolerance.

  13. Soybean GmMYB76,GmMYB92,and GmMYB177 genes confer stress tolerance in transgenic Arabidopsis plants

    Institute of Scientific and Technical Information of China (English)

    Yong Liao; Hong-Feng Zou; Hui-Wen Wang; Wan-Ke Zhang; Biao Ma; Jin-Song Zhang; Shou-Yi Chen

    2008-01-01

    MYB-type transcription factors contain the conserved MYB DNA-binding domain of approximately 50 amino acids and are involved in the regulation of many aspects of plant growth,development,metabolism and stress responses.From soybean plants,we identified 156 GmMYB genes using our previously obtained 206 MYB unigenes,and 48 were found to have full-length open-reading frames.Expressions of all these identified genes were examined,and we found that expressions of 43 genes were changed upon treatment with ABA,salt,drought and/or cold stress.Three GmMYB genes,GmMYB76,GmMYB92 and GmMYB177,were chosen for further analysis.Using the yeast assay system,GmMYB76 and GmMYB92 were found to have transactivation activity and can form homodimers.GmMYBI77 did not appear to have transactivation activity but can form heterodimers with GmMYB76.Yeast onehybrid assay revealed that all the three GmMYBs could bind to cis-elements TAT AAC GGT TTT TT and CCG GAA AAAAGG AT,but with different affinity,and GmMYB92 could also bind to TCT CAC CTA CC.The transgenic Arabidopsis plants overexpressing GmMYB76 or GmMYB177 showed better performance than the GmMYB92-transgenic plants in salt and freezing tolerance.However,these transgenic plants exhibited reduced sensitivity to ABA treatment at germination stage in comparison with the wild-type plants.The three GmMYB genes differentially affected a subset of stress-responsive genes in addition to their regulation of a common subset of stress-responsive genes.These results indicate that the three GmMYB genes may play differential roles in stress tolerance,possibly through regulation of stress-responsive genes.

  14. Activated expression of an Arabidopsis HD-START protein confers drought tolerance with improved root system and reduced stomatal density.

    Science.gov (United States)

    Yu, Hong; Chen, Xi; Hong, Yuan-Yuan; Wang, Yao; Xu, Ping; Ke, Sheng-Dong; Liu, Hai-Yan; Zhu, Jian-Kang; Oliver, David J; Xiang, Cheng-Bin

    2008-04-01

    Drought is one of the most important environmental constraints limiting plant growth and agricultural productivity. To understand the underlying mechanism of drought tolerance and to identify genes for improving this important trait, we conducted a gain-of-function genetic screen for improved drought tolerance in Arabidopsis thaliana. One mutant with improved drought tolerance was isolated and designated as enhanced drought tolerance1. The mutant has a more extensive root system than the wild type, with deeper roots and more lateral roots, and shows a reduced leaf stomatal density. The mutant had higher levels of abscisic acid and Pro than the wild type and demonstrated an increased resistance to oxidative stress and high levels of superoxide dismutase. Molecular genetic analysis and recapitulation experiments showed that the enhanced drought tolerance is caused by the activated expression of a T-DNA tagged gene that encodes a putative homeodomain-START transcription factor. Moreover, overexpressing the cDNA of the transcription factor in transgenic tobacco also conferred drought tolerance associated with improved root architecture and reduced leaf stomatal density. Therefore, we have revealed functions of the homeodomain-START factor that were gained upon altering its expression pattern by activation tagging and provide a key regulator that may be used to improve drought tolerance in plants.

  15. Overexpression of a soybean ariadne-like ubiquitin ligase gene GmARI1 enhances aluminum tolerance in Arabidopsis.

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    Xiaolian Zhang

    Full Text Available Ariadne (ARI subfamily of RBR (Ring Between Ring fingers proteins have been found as a group of putative E3 ubiquitin ligases containing RING (Really Interesting New Gene finger domains in fruitfly, mouse, human and Arabidopsis. Recent studies showed several RING-type E3 ubiquitin ligases play important roles in plant response to abiotic stresses, but the function of ARI in plants is largely unknown. In this study, an ariadne-like E3 ubiquitin ligase gene was isolated from soybean, Glycine max (L. Merr., and designated as GmARI1. It encodes a predicted protein of 586 amino acids with a RBR supra-domain. Subcellular localization studies using Arabidopsis protoplast cells indicated GmARI protein was located in nucleus. The expression of GmARI1 in soybean roots was induced as early as 2-4 h after simulated stress treatments such as aluminum, which coincided with the fact of aluminum toxicity firstly and mainly acting on plant roots. In vitro ubiquitination assay showed GmARI1 protein has E3 ligase activity. Overexpression of GmARI1 significantly enhanced the aluminum tolerance of transgenic Arabidopsis. These findings suggest that GmARI1 encodes a RBR type E3 ligase, which may play important roles in plant tolerance to aluminum stress.

  16. Overexpression of a soybean ariadne-like ubiquitin ligase gene GmARI1 enhances aluminum tolerance in Arabidopsis.

    Science.gov (United States)

    Zhang, Xiaolian; Wang, Ning; Chen, Pei; Gao, Mengmeng; Liu, Juge; Wang, Yufeng; Zhao, Tuanjie; Li, Yan; Gai, Junyi

    2014-01-01

    Ariadne (ARI) subfamily of RBR (Ring Between Ring fingers) proteins have been found as a group of putative E3 ubiquitin ligases containing RING (Really Interesting New Gene) finger domains in fruitfly, mouse, human and Arabidopsis. Recent studies showed several RING-type E3 ubiquitin ligases play important roles in plant response to abiotic stresses, but the function of ARI in plants is largely unknown. In this study, an ariadne-like E3 ubiquitin ligase gene was isolated from soybean, Glycine max (L.) Merr., and designated as GmARI1. It encodes a predicted protein of 586 amino acids with a RBR supra-domain. Subcellular localization studies using Arabidopsis protoplast cells indicated GmARI protein was located in nucleus. The expression of GmARI1 in soybean roots was induced as early as 2-4 h after simulated stress treatments such as aluminum, which coincided with the fact of aluminum toxicity firstly and mainly acting on plant roots. In vitro ubiquitination assay showed GmARI1 protein has E3 ligase activity. Overexpression of GmARI1 significantly enhanced the aluminum tolerance of transgenic Arabidopsis. These findings suggest that GmARI1 encodes a RBR type E3 ligase, which may play important roles in plant tolerance to aluminum stress.

  17. S-methylmethionine is involved in the salinity tolerance of Arabidopsis thaliana plants at germination and early growth stages.

    Science.gov (United States)

    Ogawa, Saori; Mitsuya, Shiro

    2012-01-01

    Methionine (Met) is biosynthesized by the activated methyl cycle and S-methylmethionine (SMM) cycle in one-carbon (C1) metabolism in plants. It is converted to S-adenosylmethionine (SAM) which serves as a precursor for many metabolites including glycinebetaine, methylated polyols, polyamines and ethylene which accumulate in plants in response to salinity. We have investigated how the Met biosynthetic pathway is regulated under saline conditions at the transcriptional level in Arabidopsis thaliana plants. Within Met biosynthesis-related genes, the expression of homocysteine methyltransferase (HMT) and methionine methyltransferase (MMT) genes in SMM cycle had altered toward increasing Met production by the presence of NaCl. We have determined the salinity tolerance of an Arabidopsis mmt mutant with an insertional mutation in the single copy of the AtMMT gene. Although the mmt mutant showed comparable germination and shoot growth with wild type under normal conditions, NaCl treatment caused severe repression of germination rate and shoot growth in the mmt mutant compared with in the wild type. These results indicate that the utilization of SMM is important for the salinity tolerance of Arabidopsis plants at the germination and early growth stages.

  18. Genetic variation in photosynthetic performance and tolerance to osmotic stress (desiccation, freezing, hyposalinity) in the rocky littoral foundation species Fucus vesiculosus (Fucales, Phaeophyceae).

    Science.gov (United States)

    Rothäusler, Eva; Sjöroos, Joakim; Heye, Katharina; Jormalainen, Veijo

    2016-10-01

    Genetic diversity may play an analogous role to species diversity, as it can contribute to ecosystem function and stability, and provision of ecosystem services. In the Baltic Sea, perennial algal beds are often comprised of only Fucus vesiculosus and the amount of genetic variation in fitness-related traits (i.e., the ability of the alga to photosynthesize or withstand stress) will thus determine the alga's local persistence in a changing environment. To study genetic variation in the crucial traits behind persistence we grew replicate vegetative branches that came from the same genotype in common gardens. We quantified osmotic stress tolerance and recovery responses by exposing branches to desiccation, freezing, and hyposalinity regimens. Our results show that genetic variation among genotypes was apparent for some photosynthetic parameters (maximal electron transport rate, saturation irradiance for electron transport, nonphotochemical quenching) and growth. Algae tolerated freezing (1,440 min at -2.5°C) and hyposalinity (1,560 min at 2.5) well, but did not recover from desiccation (70 min at 12°C, causing ~94% water loss). Furthermore, we found very little if any evidence on genetic variation in tolerance to these stressors. Our results suggest that low salinity and cold winters in the northern marginal populations selected for hyposalinity and freezing tolerant genotypes, possibly eroding genetic variation in tolerance, but that tolerance to harsh desiccation has been lost, likely due to relaxed selection. The overall availability of genetic variation in fitness related traits might be supportive for F. vesiculosus during adaptation to gradual changes of its environment.

  19. Research progress on improvement in freeze-tolerance of baker's yeast%提高面包酵母耐冷冻性的研究进展

    Institute of Scientific and Technical Information of China (English)

    苏从毅; 王辛; 王四维; 张福钊

    2012-01-01

    Baker yeast is a necessary material of bread making, and improvement in freeze- tolerance of baker's yeast is very important to the development of frozen dough. In this paper, the species and effects of baker's yeast were introduced, and the freeze-tolerance mechanism of baker's yeast and the development review on improvement in freeze-tolerance of baker's yeast were emphasized.%面包酵母是制作面包不可缺少的原料,提高面包酵母的耐冷冻性对冷冻面团工业的发展有着十分重要的作用。本文介绍了面包酵母的种类和作用,重点讲述了面包酵母的耐冷冻机理及国内外对提高面包酵母耐冷冻性的研究进展。

  20. Nuclear-localized AtHSPR links abscisic acid-dependent salt tolerance and antioxidant defense in Arabidopsis.

    Science.gov (United States)

    Yang, Tao; Zhang, Liang; Hao, Hongyan; Zhang, Peng; Zhu, Haowei; Cheng, Wei; Wang, Yongli; Wang, Xinyu; Wang, Chongying

    2015-12-01

    Salt stress from soil or irrigation water limits plant growth. A T-DNA insertion mutant in C24, named athspr (Arabidopsis thaliana heat shock protein-related), showed several phenotypes, including reduced organ size and enhanced sensitivity to environmental cues. The athspr mutant is severely impaired under salinity levels at which wild-type (WT) plants grow normally. AtHSPR encodes a nuclear-localized protein with ATPase activity, and its expression was enhanced by high salinity and abscisic acid (ABA). Overexpression (OE) of AtHSPR significantly enhanced tolerance to salt stress by increasing the activities of the antioxidant system and by maintaining K(+) /Na(+) homeostasis. Quantitative RT-PCR analyses showed that OE of AtHSPR increased the expression of ABA/stress-responsive, salt overly sensitive (SOS)-related and antioxidant-related genes. In addition, ABA content was reduced in athspr plants with or without salt stress, and exogenous ABA restored WT-like salt tolerance to athspr plants. athspr exhibited increased leaf stomatal density and stomatal index, slower ABA-induced stomatal closure and reduced drought tolerance relative to the WT. AtHSPR OE enhanced drought tolerance by reducing leaf water loss and stomatal aperture. Transcript profiling in athspr showed a differential salt-stress response for genes involved in accumulation of reactive oxygen species (ROS), ABA signaling, cell death, stress response and photosynthesis. Taken together, our results suggested that AtHSPR is involved in salt tolerance in Arabidopsis through modulation of ROS levels, ABA-dependent stomatal closure, photosynthesis and K(+) /Na(+) homeostasis.

  1. Macromolecular differentiation of Golgi stacks in root tips of Arabidopsis and Nicotiana seedlings as visualized in high pressure frozen and freeze-substituted samples

    Science.gov (United States)

    Staehelin, L. A.; Giddings, T. H. Jr; Kiss, J. Z.; Sack, F. D.

    1990-01-01

    The plant root tip represents a fascinating model system for studying changes in Golgi stack architecture associated with the developmental progression of meristematic cells to gravity sensing columella cells, and finally to "young" and "old", polysaccharide-slime secreting peripheral cells. To this end we have used high pressure freezing in conjunction with freeze-substitution techniques to follow developmental changes in the macromolecular organization of Golgi stacks in root tips of Arabidopsis and Nicotiana. Due to the much improved structural preservation of all cells under investigation, our electron micrographs reveal both several novel structural features common to all Golgi stacks, as well as characteristic differences in morphology between Golgi stacks of different cell types. Common to all Golgi stacks are clear and discrete differences in staining patterns and width of cis, medial and trans cisternae. Cis cisternae have the widest lumina (approximately 30 nm) and are the least stained. Medial cisternae are narrower (approximately 20 nm) and filled with more darkly staining products. Most trans cisternae possess a completely collapsed lumen in their central domain, giving rise to a 4-6 nm wide dark line in cross-sectional views. Numerous vesicles associated with the cisternal margins carry a non-clathrin type of coat. A trans Golgi network with clathrin coated vesicles is associated with all Golgi stacks except those of old peripheral cells. It is easily distinguished from trans cisternae by its blebbing morphology and staining pattern. The zone of ribosome exclusion includes both the Golgi stack and the trans Golgi network. Intercisternal elements are located exclusively between trans cisternae of columella and peripheral cells, but not meristematic cells. In older peripheral cells only trans cisternae exhibit slime-related staining. Golgi stacks possessing intercisternal elements also contain parallel rows of freeze-fracture particles in their trans

  2. A thaumatin-like protein of Ocimum basilicum confers tolerance to fungal pathogen and abiotic stress in transgenic Arabidopsis.

    Science.gov (United States)

    Misra, Rajesh Chandra; Sandeep; Kamthan, Mohan; Kumar, Santosh; Ghosh, Sumit

    2016-05-06

    Plant often responds to fungal pathogens by expressing a group of proteins known as pathogenesis-related proteins (PRs). The expression of PR is mediated through pathogen-induced signal-transduction pathways that are fine-tuned by phytohormones such as methyl jasmonate (MeJA). Here, we report functional characterization of an Ocimum basilicum PR5 family member (ObTLP1) that was identified from a MeJA-responsive expression sequence tag collection. ObTLP1 encodes a 226 amino acid polypeptide that showed sequence and structural similarities with a sweet-tasting protein thaumatin of Thaumatococcus danielli and also with a stress-responsive protein osmotin of Nicotiana tabacum. The expression of ObTLP1 in O. basilicum was found to be organ-preferential under unstressed condition, and responsive to biotic and abiotic stresses, and multiple phytohormone elicitations. Bacterially-expressed recombinant ObTLP1 inhibited mycelial growth of the phytopathogenic fungi, Scleretonia sclerotiorum and Botrytis cinerea; thereby, suggesting its antifungal activity. Ectopic expression of ObTLP1 in Arabidopsis led to enhanced tolerance to S. sclerotiorum and B. cinerea infections, and also to dehydration and salt stress. Moreover, induced expression of the defense marker genes suggested up-regulation of the defense-response pathways in ObTLP1-expressing Arabidopsis upon fungal challenge. Thus, ObTLP1 might be useful for providing tolerance to the fungal pathogens and abiotic stresses in crops.

  3. Enhanced drought tolerance in Arabidopsis via genetic manipulation aimed at the reduction of glucosamine-induced ROS generation.

    Science.gov (United States)

    Chu, Seung Hee; Noh, Ha-na; Kim, Sooah; Kim, Kyoung Heon; Hong, Suk-Whan; Lee, Hojoung

    2010-11-01

    In animals, high glucose exerts some of its deleterious effects by activation of the hexosamine biosynthesis pathway (HBP), a branch of the glycolytic pathway that produces amino sugars (Daniels et al. in Mol Endocrinol 7:1041-1048, 1993; Du et al. in Proc Natl Acad Sci USA 97:12222-12226, 2000). Glucosamine (GlcN) is a naturally occurring amino sugar produced by amidation of fructose-6-phosphate. Previously, we observed that glucosamine (GlcN) inhibits hypocotyl elongation in Arabidopsis thaliana by a process involving the significant increase of reactive oxygen species. The present study investigated the relationship between GlcN-induced ROS generation and abiotic stress responses in Arabidopsis by generating two types of transgenic plant. Scavenging of endogenous GlcN by ectopic expression of E. coli glucosamine-6-phosphate deaminase (NagB) was observed to confer enhanced tolerance to oxidative, drought, and cold stress. Consistent with this result, overproduction of GlcN by the ectopic expression of E. coli glucosamine-6-phosphate synthase (GlmS) induced cell death at an early stage. Taken together, these data suggest that genetic manipulation of endogenous GlcN level can effectively lead to the generation of abiotic stress-tolerant transgenic crop plants.

  4. OsSGL, a Novel DUF1645 Domain-Containing Protein, Confers Enhanced Drought Tolerance in Transgenic Rice and Arabidopsis.

    Science.gov (United States)

    Cui, Yanchun; Wang, Manling; Zhou, Huina; Li, Mingjuan; Huang, Lifang; Yin, Xuming; Zhao, Guoqiang; Lin, Fucheng; Xia, Xinjie; Xu, Guoyun

    2016-01-01

    Drought is a major environmental factor that limits plant growth and crop productivity. Genetic engineering is an effective approach to improve drought tolerance in various crops, including rice (Oryza sativa). Functional characterization of relevant genes is a prerequisite when identifying candidates for such improvements. We investigated OsSGL (Oryza sativa Stress tolerance and Grain Length), a novel DUF1645 domain-containing protein from rice. OsSGL was up-regulated by multiple stresses and localized to the nucleus. Transgenic plants over-expressing or hetero-expressing OsSGL conferred significantly improved drought tolerance in transgenic rice and Arabidopsis thaliana, respectively. The overexpressing plants accumulated higher levels of proline and soluble sugars but lower malondialdehyde (MDA) contents under osmotic stress. Our RNA-sequencing data demonstrated that several stress-responsive genes were significantly altered in transgenic rice plants. We unexpectedly observed that those overexpressing rice plants also had extensive root systems, perhaps due to the altered transcript levels of auxin- and cytokinin-associated genes. These results suggest that the mechanism by which OsSGL confers enhanced drought tolerance is due to the modulated expression of stress-responsive genes, higher accumulations of osmolytes, and enlarged root systems.

  5. Overexpression of the poplar NF-YB7 transcription factor confers drought tolerance and improves water-use efficiency in Arabidopsis.

    Science.gov (United States)

    Han, Xiao; Tang, Sha; An, Yi; Zheng, Dong-Chao; Xia, Xin-Li; Yin, Wei-Lun

    2013-11-01

    Water deficit is a serious environmental factor limiting the growth and productivity of plants worldwide. Improvement of drought tolerance and efficient water use are significant strategies to overcome this dilemma. In this study, a drought-responsive transcription factor, nuclear factor Y subunit B 7 (PdNF-YB7), induced by osmotic stress (PEG6000) and abscisic acid, was isolated from fast-growing poplar clone NE-19 [Populus nigra × (Populus deltoides × Populus nigra)]. Ectopic overexpression of PdNF-YB7 (oxPdB7) in Arabidopsis enhanced drought tolerance and whole-plant and instantaneous leaf water-use efficiency (WUE, the ratio of biomass produced to water consumed). Overexpressing lines had an increase in germination rate and root length and decrease in water loss and displayed higher photosynthetic rate, instantaneous leaf WUE, and leaf water potential to exhibit enhanced drought tolerance under water scarcity. Additionally, overexpression of PdNF-YB7 in Arabidopsis improved whole-plant WUE by increasing carbon assimilation and reducing transpiration with water abundance. These drought-tolerant, higher WUE transgenic Arabidopsis had earlier seedling establishment and higher biomass than controls under normal and drought conditions. In contrast, Arabidopsis mutant nf-yb3 was more sensitive to drought stress with lower WUE. However, complementation analysis indicated that complementary lines (nf-yb3/PdB7) had almost the same drought response and WUE as wild-type Col-0. Taken together, these results suggest that PdNF-YB7 positively confers drought tolerance and improves WUE in Arabidopsis; thus it could potentially be used in breeding drought-tolerant plants with increased production even under water deficiency.

  6. Brassica RNA binding protein ERD4 is involved in conferring salt, drought tolerance and enhancing plant growth in Arabidopsis.

    Science.gov (United States)

    Rai, Archana N; Tamirisa, Srinath; Rao, K V; Kumar, Vinay; Suprasanna, P

    2016-03-01

    'Early responsive to dehydration' (ERD) genes are a group of plant genes having functional roles in plant stress tolerance and development. In this study, we have isolated and characterized a Brassica juncea 'ERD' gene (BjERD4) which encodes a novel RNA binding protein. The expression pattern of ERD4 analyzed under different stress conditions showed that transcript levels were increased with dehydration, sodium chloride, low temperature, heat, abscisic acid and salicylic acid treatments. The BjERD4 was found to be localized in the chloroplasts as revealed by Confocal microscopy studies. To study the function, transgenic Arabidopsis plants were generated and analyzed for various morphological and physiological parameters. The overexpressing transgenic lines showed significant increase in number of leaves with more leaf area and larger siliques as compared to wild type plants, whereas RNAi:ERD4 transgenic lines showed reduced leaf number, leaf area, dwarf phenotype and delayed seed germination. Transgenic Arabidopsis plants overexpressing BjERD4 gene also exhibited enhanced tolerance to dehydration and salt stresses, while the knockdown lines were susceptible as compared to wild type plants under similar stress conditions. It was observed that BjERD4 protein could bind RNA as evidenced by the gel-shift assay. The overall results of transcript analysis, RNA gel-shift assay, and transgenic expression, for the first time, show that the BjERD4 is involved in abiotic stress tolerance besides offering new clues about the possible roles of BjERD4 in plant growth and development.

  7. Tolerance to excess-boron conditions acquired by stabilization of a BOR1 variant with weak polarity in Arabidopsis

    Directory of Open Access Journals (Sweden)

    Shinji eWakuta

    2016-02-01

    Full Text Available Boron (B is a metalloid that is essential for plant growth but is toxic when present in excess. Arabidopsis BOR1 is a borate exporter, facilitating B translocation from root to shoot under limited-B conditions. BOR1 shows stele side polar localization in the plasma membrane of various root cells, presumably to support B translocation toward the stele. BOR1 is degraded under high-B supply through vacuolar sorting via ubiquitination at the K590 residue to prevent the accumulation of B to a toxic level in shoots. A previous study showed that overexpression of BOR1 under control of the cauliflower mosaic virus 35S RNA promoter improved the growth of Arabidopsis under limited-B conditions without affecting the growth under sufficient-to-excess-B conditions. In this study, we unexpectedly found that ubiquitous expression of a stabilized BOR1 variant improved tolerance to excess-B in Arabidopsis. We established transgenic plants expressing BOR1-GFP fused with hygromycin phosphotransferase (HPT and BOR1(K590A-GFP-HPT under control of the ubiquitin 10 promoter. BOR1-GFP-HPT and BOR1(K590A-GFP-HPT were expressed in various cell types in leaves and roots and showed weak polar localization in root tip cells. BOR1-GFP-HPT, but not BOR1(K590A-GFP-HPT, was degraded through an endocytic pathway under high-B conditions. Transgenic plants with the stabilized variant BOR1(K590A-GFP-HPT showed improved root and shoot growth under excess-B conditions. The concentration of B was greater in the shoots of plants with BOR1(K590A-GFP-HPT or BOR1-GFP-HPT than in those of untransformed wild-type plants. These results suggest that BOR1(K590A-GFP-HPT confers tolerance to excess-B by excluding B from the cytosol of shoot cells. Results from this study indicate the potential for engineering the trafficking properties of a transporter to produce plants that are tolerant to mineral stress.

  8. Anastatica hierochuntica, an Arabidopsis Desert Relative, Is Tolerant to Multiple Abiotic Stresses and Exhibits Species-Specific and Common Stress Tolerance Strategies with Its Halophytic Relative, Eutrema (Thellungiella) salsugineum

    Science.gov (United States)

    Eshel, Gil; Shaked, Ruth; Kazachkova, Yana; Khan, Asif; Eppel, Amir; Cisneros, Aroldo; Acuna, Tania; Gutterman, Yitzhak; Tel-Zur, Noemi; Rachmilevitch, Shimon; Fait, Aaron; Barak, Simon

    2017-01-01

    The search for novel stress tolerance determinants has led to increasing interest in plants native to extreme environments – so called “extremophytes.” One successful strategy has been comparative studies between Arabidopsis thaliana and extremophyte Brassicaceae relatives such as the halophyte Eutrema salsugineum located in areas including cold, salty coastal regions of China. Here, we investigate stress tolerance in the desert species, Anastatica hierochuntica (True Rose of Jericho), a member of the poorly investigated lineage III Brassicaceae. We show that A. hierochuntica has a genome approximately 4.5-fold larger than Arabidopsis, divided into 22 diploid chromosomes, and demonstrate that A. hierochuntica exhibits tolerance to heat, low N and salt stresses that are characteristic of its habitat. Taking salt tolerance as a case study, we show that A. hierochuntica shares common salt tolerance mechanisms with E. salsugineum such as tight control of shoot Na+ accumulation and resilient photochemistry features. Furthermore, metabolic profiling of E. salsugineum and A. hierochuntica shoots demonstrates that the extremophytes exhibit both species-specific and common metabolic strategies to cope with salt stress including constitutive up-regulation (under control and salt stress conditions) of ascorbate and dehydroascorbate, two metabolites involved in ROS scavenging. Accordingly, A. hierochuntica displays tolerance to methyl viologen-induced oxidative stress suggesting that a highly active antioxidant system is essential to cope with multiple abiotic stresses. We suggest that A. hierochuntica presents an excellent extremophyte Arabidopsis relative model system for understanding plant survival in harsh desert conditions. PMID:28144244

  9. Study of natural variation for Zn deficiency tolerance in Arabidopsis thaliana

    NARCIS (Netherlands)

    Campos, A.C.A.L.

    2015-01-01

    English summary Zinc is an important structural component and co-factor of proteins in all living organisms. The model plant species for genetic and molecular studies, Arabidopsis thaliana, expresses more than 2,000 proteins with one or more Zn binding domains. Low Zn availability i

  10. Transgenic poplar expressing Arabidopsis YUCCA6 exhibits auxin-overproduction phenotypes and increased tolerance to abiotic stress.

    Science.gov (United States)

    Ke, Qingbo; Wang, Zhi; Ji, Chang Yoon; Jeong, Jae Cheol; Lee, Haeng-Soon; Li, Hongbing; Xu, Bingcheng; Deng, Xiping; Kwak, Sang-Soo

    2015-09-01

    YUCCA6, a member of the YUCCA family of flavin monooxygenase-like proteins, is involved in the tryptophan-dependent IAA biosynthesis pathway and responses to environmental cues in Arabidopsis. However, little is known about the role of the YUCCA pathway in auxin biosynthesis in poplar. Here, we generated transgenic poplar (Populus alba × P. glandulosa) expressing the Arabidopsis YUCCA6 gene under the control of the oxidative stress-inducible SWPA2 promoter (referred to as SY plants). Three SY lines (SY7, SY12 and SY20) were selected based on the levels of AtYUCCA6 transcript. SY plants displayed auxin-overproduction morphological phenotypes, such as rapid shoot growth and retarded main root development with increased root hair formation. In addition, SY plants had higher levels of free IAA and early auxin-response gene transcripts. SY plants exhibited tolerance to drought stress, which was associated with reduced levels of reactive oxygen species. Furthermore, SY plants showed delayed hormone- and dark-induced senescence in detached leaves due to higher photosystem II efficiency and less membrane permeability. These results suggest that the conserved IAA biosynthesis pathway mediated by YUCCA family members exists in poplar.

  11. Estimating Broad Sense Heritability and Investigating the Mechanism of Genetic Transmission of Cold Tolerance Using Mannitol as a Measure of Post-freeze Juice Degradation in Sugarcane and Energycane (Saccharum spp.).

    Science.gov (United States)

    Hale, Anna L; Viator, Ryan P; Eggleston, Gillian; Hodnett, George; Stelly, David M; Boykin, Debbie; Miller, Donnie K

    2016-03-01

    In approximately 25% of the sugarcane-producing countries worldwide, conventional sugarcane (Saccharum spp. hybrids) is exposed to damaging freezes. A study was conducted during the 2009 and 2010 harvest seasons to compare late-season freeze tolerance among three groups: commercial Louisiana sugarcane genotypes, early generation genotypes selected for cold tolerance in the U.S. Department of Agriculture sugarcane breeding programs at Houma, LA, and Canal Point, FL, and potential energycane genotypes selected for high total biomass per acre. Mannitol concentrations in cane juice following freezing temperatures were determined to evaluate levels of cold tolerance. Genotypes selected for cold tolerance in Houma, LA, had significantly more late-season freeze tolerance than commercial sugarcane genotypes and genotypes selected in Canal Point, FL. Genotypes showing the most cold tolerance were Ho02-146 and Ho02-152, and those that were most highly susceptible were US87-1006 and US87-1003 (early-generation breeding genotypes) and L99-233 (commercial genotype). Broad-sense heritability for late-season cold tolerance in the two-year study was estimated at g(2) = 0.78. The enzymatic mannitol analysis successfully differentiated high-fiber energycane genotypes from those from other sources.

  12. Engineering carpel-specific cold stress tolerance: a case study in Arabidopsis

    Science.gov (United States)

    Freezing temperatures during winter generally do not injure floral buds of horticulturally important crops. Entry into dormancy coupled with cold acclimation provides adequate protection unless the temperatures are exceptionally low. This measure of protection is lost in spring when the floral bud...

  13. Comparative proteomic analysis of differentially expressed proteins in β-aminobutyric acid enhanced Arabidopsis thaliana tolerance to simulated acid rain.

    Science.gov (United States)

    Liu, Tingwu; Jiang, Xinwu; Shi, Wuliang; Chen, Juan; Pei, Zhenming; Zheng, Hailei

    2011-05-01

    Acid rain is a worldwide environmental issue that has seriously destroyed forest ecosystems. As a highly effective and broad-spectrum plant resistance-inducing agent, β-aminobutyric acid could elevate the tolerance of Arabidopsis when subjected to simulated acid rain. Using comparative proteomic strategies, we analyzed 203 significantly varied proteins of which 175 proteins were identified responding to β-aminobutyric acid in the absence and presence of simulated acid rain. They could be divided into ten groups according to their biological functions. Among them, the majority was cell rescue, development and defense-related proteins, followed by transcription, protein synthesis, folding, modification and destination-associated proteins. Our conclusion is β-aminobutyric acid can lead to a large-scale primary metabolism change and simultaneously activate antioxidant system and salicylic acid, jasmonic acid, abscisic acid signaling pathways. In addition, β-aminobutyric acid can reinforce physical barriers to defend simulated acid rain stress.

  14. Overexpression of WsSGTL1 gene of Withania somnifera enhances salt tolerance, heat tolerance and cold acclimation ability in transgenic Arabidopsis plants.

    Directory of Open Access Journals (Sweden)

    Manoj K Mishra

    Full Text Available BACKGROUND: Sterol glycosyltrnasferases (SGT are enzymes that glycosylate sterols which play important role in plant adaptation to stress and are medicinally important in plants like Withania somnifera. The present study aims to find the role of WsSGTL1 which is a sterol glycosyltransferase from W. somnifera, in plant's adaptation to abiotic stress. METHODOLOGY: The WsSGTL1 gene was transformed in Arabidopsis thaliana through Agrobacterium mediated transformation, using the binary vector pBI121, by floral dip method. The phenotypic and physiological parameters like germination, root length, shoot weight, relative electrolyte conductivity, MDA content, SOD levels, relative electrolyte leakage and chlorophyll measurements were compared between transgenic and wild type Arabidopsis plants under different abiotic stresses--salt, heat and cold. Biochemical analysis was done by HPLC-TLC and radiolabelled enzyme assay. The promoter of the WsSGTL1 gene was cloned by using Genome Walker kit (Clontech, USA and the 3D structures were predicted by using Discovery Studio Ver. 2.5. RESULTS: The WsSGTL1 transgenic plants were confirmed to be single copy by Southern and homozygous by segregation analysis. As compared to WT, the transgenic plants showed better germination, salt tolerance, heat and cold tolerance. The level of the transgene WsSGTL1 was elevated in heat, cold and salt stress along with other marker genes such as HSP70, HSP90, RD29, SOS3 and LEA4-5. Biochemical analysis showed the formation of sterol glycosides and increase in enzyme activity. When the promoter of WsSGTL1 gene was cloned from W. somnifera and sequenced, it contained stress responsive elements. Bioinformatics analysis of the 3D structure of the WsSGTL1 protein showed functional similarity with sterol glycosyltransferase AtSGT of A. thaliana. CONCLUSIONS: Transformation of WsSGTL1 gene in A. thaliana conferred abiotic stress tolerance. The promoter of the gene in W.somnifera was found

  15. Overexpression of phytochelatin synthase in Arabidopsis leads to enhanced arsenic tolerance and cadmium hypersensitivity.

    Science.gov (United States)

    Li, Yujing; Dhankher, Om Parkash; Carreira, Laura; Lee, David; Chen, Alice; Schroeder, Julian I; Balish, Rebecca S; Meagher, Richard B

    2004-12-01

    Phytochelatin synthase (PCS) catalyzes the final step in the biosynthesis of phytochelatins, which are a family of cysteine-rich thiol-reactive peptides believed to play important roles in processing many thiol-reactive toxicants. A modified Arabidopsis thaliana PCS sequence (AtPCS1) was active in Escherichia coli. When AtPCS1 was overexpressed in Arabidopsis from a strong constitutive Arabidopsis actin regulatory sequence (A2), the A2::AtPCS1 plants were highly resistant to arsenic, accumulating 20-100 times more biomass on 250 and 300 microM arsenate than wild type (WT); however, they were hypersensitive to Cd(II). After exposure to cadmium and arsenic, the overall accumulation of thiol-peptides increased to 10-fold higher levels in the A2::AtPCS1 plants compared with WT, as determined by fluorescent HPLC. Whereas cadmium induced greater increases in traditional PCs (PC2, PC3, PC4), arsenic exposure resulted in the expression of many unknown thiol products. Unexpectedly, after arsenate or cadmium exposure, levels of the dipeptide substrate for PC synthesis, gamma-glutamyl cysteine (gamma-EC), were also dramatically increased. Despite these high thiol-peptide concentrations, there were no significant increases in concentrations of arsenic and cadmium in above-ground tissues in the AtPCS1 plants relative to WT plants. The potential for AtPCS1 overexpression to be useful in strategies for phytoremediating arsenic and to compound the negative effects of cadmium are discussed.

  16. Hydrogen sulfide improves drought tolerance in Arabidopsis thaliana by microRNA expressions.

    Directory of Open Access Journals (Sweden)

    Jiejie Shen

    Full Text Available Hydrogen sulfide (H2S is a gasotransmitter and plays an important role in many physiological processes in mammals. Studies of its functions in plants are attracting ever growing interest, for example, its ability to enhance drought resistance in Arabidopsis. A general role of microRNAs (miRNAs in plant adaptive responses to drought stress has thereby increased our interest to delve into the possible interplay between H2S and miRNAs. Our results showed that treating wild type (WT Arabidopsis seedlings with polyethylene glycol 8000 (PEG8000 to simulate drought stress caused an increase in production rate of endogenous H2S; and a significant transcriptional reformation of relevant miRNAs, which were also triggered by exogenous H2S in WT. When lcd mutants (with lower H2S production rate than WT were treated with PEG8000, they showed lower levels of miRNA expression changes than WT. In addition, we detected significant changes in target gene expression of those miRNAs and the corresponding phenotypes in lcd, including less roots, retardation of leaf growth and development and greater superoxide dismutase (SOD activity under drought stress. We thereby conclude that H2S can improve drought resistance through regulating drought associated miRNAs in Arabidopsis.

  17. Salt-induced stabilization of EIN3/EIL1 confers salinity tolerance by deterring ROS accumulation in Arabidopsis.

    Directory of Open Access Journals (Sweden)

    Jinying Peng

    2014-10-01

    Full Text Available Ethylene has been regarded as a stress hormone to regulate myriad stress responses. Salinity stress is one of the most serious abiotic stresses limiting plant growth and development. But how ethylene signaling is involved in plant response to salt stress is poorly understood. Here we showed that Arabidopsis plants pretreated with ethylene exhibited enhanced tolerance to salt stress. Gain- and loss-of-function studies demonstrated that EIN3 (ETHYLENE INSENSITIVE 3 and EIL1 (EIN3-LIKE 1, two ethylene-activated transcription factors, are necessary and sufficient for the enhanced salt tolerance. High salinity induced the accumulation of EIN3/EIL1 proteins by promoting the proteasomal degradation of two EIN3/EIL1-targeting F-box proteins, EBF1 and EBF2, in an EIN2-independent manner. Whole-genome transcriptome analysis identified a list of SIED (Salt-Induced and EIN3/EIL1-Dependent genes that participate in salt stress responses, including several genes encoding reactive oxygen species (ROS scavengers. We performed a genetic screen for ein3 eil1-like salt-hypersensitive mutants and identified 5 EIN3 direct target genes including a previously unknown gene, SIED1 (At5g22270, which encodes a 93-amino acid polypeptide involved in ROS dismissal. We also found that activation of EIN3 increased peroxidase (POD activity through the direct transcriptional regulation of PODs expression. Accordingly, ethylene pretreatment or EIN3 activation was able to preclude excess ROS accumulation and increased tolerance to salt stress. Taken together, our study provides new insights into the molecular action of ethylene signaling to enhance plant salt tolerance, and elucidates the transcriptional network of EIN3 in salt stress response.

  18. bHLH106 Integrates Functions of Multiple Genes through Their G-Box to Confer Salt Tolerance on Arabidopsis.

    Directory of Open Access Journals (Sweden)

    Aftab Ahmad

    Full Text Available An activation-tagging methodology was applied to dedifferentiated calli of Arabidopsis to identify new genes involved in salt tolerance. This identified salt tolerant callus 8 (stc8 as a gene encoding the basic helix-loop-helix transcription factor bHLH106. bHLH106-knockout (KO lines were more sensitive to NaCl, KCl, LiCl, ABA, and low temperatures than the wild-type. Back-transformation of the KO line rescued its phenotype, and over-expression (OX of bHLH106 in differentiated plants exhibited tolerance to NaCl. Green fluorescent protein (GFP fused with bHLH106 revealed that it was localized to the nucleus. Prepared bHLH106 protein was subjected to electrophoresis mobility shift assays against E-box sequences (5'-CANNTG-3'. The G-box sequence 5'-CACGTG-3' had the strongest interaction with bHLH106. bHLH106-OX lines were transcriptomically analyzed, and resultant up- and down-regulated genes selected on the criterion of presence of a G-box sequence. There were 198 genes positively regulated by bHLH106 and 36 genes negatively regulated; these genes possessed one or more G-box sequences in their promoter regions. Many of these genes are known to be involved in abiotic stress response. It is concluded that bHLH106 locates at a branching point in the abiotic stress response network by interacting directly to the G-box in genes conferring salt tolerance on plants.

  19. Multiple abiotic stress tolerance of the transformants yeast cells and the transgenic Arabidopsis plants expressing a novel durum wheat catalase.

    Science.gov (United States)

    Feki, Kaouthar; Kamoun, Yosra; Ben Mahmoud, Rihem; Farhat-Khemakhem, Ameny; Gargouri, Ali; Brini, Faiçal

    2015-12-01

    Catalases are reactive oxygen species scavenging enzymes involved in response to abiotic and biotic stresses. In this study, we described the isolation and functional characterization of a novel catalase from durum wheat, designed TdCAT1. Molecular Phylogeny analyses showed that wheat TdCAT1 exhibited high amino acids sequence identity to other plant catalases. Sequence homology analysis showed that TdCAT1 protein contained the putative calmodulin binding domain and a putative conserved internal peroxisomal targeting signal PTS1 motif around its C-terminus. Predicted three-dimensional structural model revealed the presence of four putative distinct structural regions which are the N-terminal arm, the β-barrel, the wrapping and the α-helical domains. TdCAT1 protein had the heme pocket that was composed by five essential residues. TdCAT1 gene expression analysis showed that this gene was induced by various abiotic stresses in durum wheat. The expression of TdCAT1 in yeast cells and Arabidopsis plants conferred tolerance to several abiotic stresses. Compared with the non-transformed plants, the transgenic lines maintained their growth and accumulated more proline under stress treatments. Furthermore, the amount of H2O2 was lower in transgenic lines, which was due to the high CAT and POD activities. Taken together, these data provide the evidence for the involvement of durum wheat catalase TdCAT1 in tolerance to multiple abiotic stresses in crop plants.

  20. NPR1-dependent salicylic acid signaling is not involved in elevated CO2-induced heat stress tolerance in Arabidopsis thaliana.

    Science.gov (United States)

    Ahammed, Golam Jalal; Li, Xin; Yu, Jingquan; Shi, Kai

    2015-01-01

    Elevated CO2 can protect plants from heat stress (HS); however, the underlying mechanisms are largely unknown. Here, we used a set of Arabidopsis mutants such as salicylic acid (SA) signaling mutants nonexpressor of pathogenesis-related gene 1 (npr1-1 and npr1-5) and heat-shock proteins (HSPs) mutants (hsp21 and hsp70-1) to understand the requirement of SA signaling and HSPs in elevated CO2-induced HS tolerance. Under ambient CO2 (380 µmol mol(-1)) conditions, HS (42°C, 24 h) drastically decreased maximum photochemical efficiency of PSII (Fv/Fm) in all studied plant groups. Enrichment of CO2 (800 µmol mol(-1)) with HS remarkably increased the Fv/Fm value in all plant groups except hsp70-1, indicating that NPR1-dependent SA signaling is not involved in the elevated CO2-induced HS tolerance. These results also suggest an essentiality of HSP70-1, but not HSP21 in elevated CO2-induced HS mitigation.

  1. Over-expression of histone H3K4 demethylase gene JMJ15 enhances salt tolerance in Arabidopsis

    Directory of Open Access Journals (Sweden)

    Yuan eShen

    2014-06-01

    Full Text Available Histone H3 lysine 4 trimethylation (H3K4me3 has been shown to be involved in stress-responsive gene expression and gene priming in plants. However, the role of H3K4me3 resetting in the processes is not clear. In this work we studied the expression and function of Arabidopsis H3K4 demethylase gene JMJ15. We show that the expression of JMJ15 was relatively low and was limited to a number of tissues during vegetative growth but was higher in young floral organs. Over-expression of the gene in gain-of-function mutants reduced the plant height with accumulation of lignin in stems, while the loss-of-function mutation did not produce any visible phenotype. The gain-of-function mutants showed enhanced salt tolerance, whereas the loss-of-function mutant was more sensitive to salt compared to the wild type. Transcriptomic analysis revealed that over-expression of JMJ15 down-regulated many genes which are preferentially marked by H3K4me3 and H3K4me2. Many of the down-regulated genes encode transcription regulators involved in stress responses. The data suggest that increased JMJ15 levels may regulate the gene expression program that enhances stress tolerance.

  2. 游离高表达Mal62基因对面包酵母耐冷冻性的影响%Effects of High-expressed Ma162 Gene on Freezing Tolerance of Baker's Yeast

    Institute of Scientific and Technical Information of China (English)

    孙溪; 张翠英; 董建; 吴鸣月; 王光路; 肖冬光

    2012-01-01

    通过测定胞内海藻糖积累量、冷冻前后相对发酵力以及存活率的变化,对比游离高表达麦芽糖酶基因(Md62)的突变株BYCPM与亲本BY14的海藻糖合成能力,研究Ma/62基因游离高表达与酵母耐冷冻性之间的关系。结果表明.Ma/62基因游离高表达与酵母耐冷冻性有一定的相关性,突变株耐冷冻性改善,其在烘焙产业中具有潜在商业价值。%AThe relations between high-expressed Ma162 gene and freezing tolerance of baker's yeast were investigated through measuring the accumulating quantity of intracellular trehalose, observing the change of cell fermenting power and cell viability before and after freezing, and com- paring trehalose synthesis of parent strain BY14 and mutant strain BYCPM. The results showed that there was certain relativity between high-expressed ma/62 gene and freezing tolerance of baker' s yeast (freezing tolerance got improved for mutant strain). Accordingly, the improved freezing tolerance of BYCPM may make it useful in commercial baking industry.

  3. Zinc-Finger Transcription Factor ZAT6 Positively Regulates Cadmium Tolerance through the Glutathione-Dependent Pathway in Arabidopsis1[OPEN

    Science.gov (United States)

    Chen, Jian; Yan, Xingxing; Liu, Yunlei; Wang, Ren; Fan, Tingting; Ren, Yongbing; Tang, Xiaofeng; Xiao, Fangming

    2016-01-01

    Cadmium (Cd) is an environmental pollutant with high toxicity to animals and plants. It has been established that the glutathione (GSH)-dependent phytochelatin (PC) synthesis pathway is one of the most important mechanisms contributing to Cd accumulation and tolerance in plants. However, the transcription factors involved in regulating GSH-dependent PC synthesis pathway remain largely unknown. Here, we identified an Arabidopsis (Arabidopsis thaliana) Cd-resistant mutant xcd2-D (XVE system-induced cadmium-tolerance2) using a forward genetics approach. The mutant gene underlying xcd2-D mutation was revealed to encode a known zinc-finger transcription factor, ZAT6. Transgenic plants overexpressing ZAT6 showed significant increase of Cd tolerance, whereas loss of function of ZAT6 led to decreased Cd tolerance. Increased Cd accumulation and tolerance in ZAT6-overexpressing lines was GSH dependent and associated with Cd-activated synthesis of PC, which was correlated with coordinated activation of PC-synthesis related gene expression. By contrast, loss of function of ZAT6 reduced Cd accumulation and tolerance, which was accompanied by abolished PC synthesis and gene expression. Further analysis revealed that ZAT6 positively regulates the transcription of GSH1, GSH2, PCS1, and PCS2, but ZAT6 is capable of specifically binding to GSH1 promoter in vivo. Consistently, overexpression of GSH1 has been shown to restore Cd sensitivity in the zat6-1 mutant, suggesting that GSH1 is a key target of ZAT6. Taken together, our data provide evidence that ZAT6 coordinately activates PC synthesis-related gene expression and directly targets GSH1 to positively regulate Cd accumulation and tolerance in Arabidopsis. PMID:26983992

  4. Arabidopsis EDT1/HDG11 improves drought and salt tolerance in cotton and poplar and increases cotton yield in the field.

    Science.gov (United States)

    Yu, Lin-Hui; Wu, Shen-Jie; Peng, Yi-Shu; Liu, Rui-Na; Chen, Xi; Zhao, Ping; Xu, Ping; Zhu, Jian-Bo; Jiao, Gai-Li; Pei, Yan; Xiang, Cheng-Bin

    2016-01-01

    Drought and salinity are two major environmental factors limiting crop production worldwide. Improvement of drought and salt tolerance of crops with transgenic approach is an effective strategy to meet the demand of the ever-growing world population. Arabidopsis ENHANCED DROUGHT TOLERANCE1/HOMEODOMAIN GLABROUS11 (AtEDT1/HDG11), a homeodomain-START transcription factor, has been demonstrated to significantly improve drought tolerance in Arabidopsis, tobacco, tall fescue and rice. Here we report that AtHDG11 also confers drought and salt tolerance in upland cotton (Gossypium hirsutum) and woody plant poplar (Populus tomentosa Carr.). Our results showed that both the transgenic cotton and poplar exhibited significantly enhanced tolerance to drought and salt stress with well-developed root system. In the leaves of the transgenic cotton plants, proline content, soluble sugar content and activities of reactive oxygen species-scavenging enzymes were significantly increased after drought and salt stress compared with wild type. Leaf stomatal density was significantly reduced, whereas stomatal and leaf epidermal cell size were significantly increased in both the transgenic cotton and poplar plants. More importantly, the transgenic cotton showed significantly improved drought tolerance and better agronomic performance with higher cotton yield in the field both under normal and drought conditions. These results demonstrate that AtHDG11 is not only a promising candidate for crops improvement but also for woody plants.

  5. A wheat salinity-induced WRKY transcription factor TaWRKY93 confers multiple abiotic stress tolerance in Arabidopsis thaliana.

    Science.gov (United States)

    Qin, Yuxiang; Tian, Yanchen; Liu, Xiuzhi

    2015-08-21

    Wheat is an important crop in the world. But most of the cultivars are salt sensitive, and often adversely affected by salt stress. WRKY transcription factors play a major role in plant responses to salt stress, but the effective salinity regulatory WRKYs identified in bread wheat are limited and the mechanism of salt stress tolerance is also not well explored. Here, we identified a salt (NaCl) induced class II WRKY transcription factor TaWRKY93. Its transcript level was strongly induced by salt (NaCl) and exogenous abscisic acid (ABA). Over-expression of TaWRKY93 in Arabidopsis thaliana enhanced salt (NaCl), drought, low temperature and osmotic (mannitol) stress tolerance, mainly demonstrated by transgenic plants forming longer primary roots or more lateral roots on MS plates supplemented with NaCl and mannitol individually, higher survival rate under drought and low temperature stress. Further, transgenic plants maintained a more proline content, higher relative water content and less electrolyte leakage than the wild type plants. The transcript abundance of a series of abiotic stress-related genes was up-regulated in the TaWRKY93 transgenic plants. In summary, TaWRKY93 is a new positive regulator of abiotic stress, it may increase salinity, drought and low temperature stress tolerance through enhancing osmotic adjustment, maintaining membrane stability and increasing transcription of stress related genes, and contribute to the superior agricultural traits of SR3 through promoting root development. It can be used as a candidate gene for wheat transgenic engineering breeding against abiotic stress.

  6. Overexpression of an alfalfa GDP-mannose 3, 5-epimerase gene enhances acid, drought and salt tolerance in transgenic Arabidopsis by increasing ascorbate accumulation.

    Science.gov (United States)

    Ma, Lichao; Wang, Yanrong; Liu, Wenxian; Liu, Zhipeng

    2014-11-01

    GDP-mannose 3', 5'-epimerase (GME) catalyses the conversion of GDP-D-mannose to GDP-L-galactose, an important step in the ascorbic acid (ascorbic acid) biosynthetic pathway in higher plants. In this study, a novel cDNA fragment (MsGME) encoding a GME protein was isolated and characterised from alfalfa (Medicago sativa). An expression analysis confirmed that MsGME expression was induced by salinity, PEG and acidity stresses. MsGME overexpression in Arabidopsis enhanced tolerance of the transgenic plants to salt, drought and acid. Real-time PCR analysis revealed that the transcript levels of GDP-D-mannose pyrophosphorylase (GMP), L-galactose-phosphate 1-P phosphatase (GP) and GDP-L-galactose phosphorylase (GGP) were increased in transgenic Arabidopsis (T3 generation). Moreover, the ascorbate content was increased in transgenic Arabidopsis. Our results suggest that MsGME can effectively enhance tolerance of transgenic Arabidopsis to acid, drought and salt by increasing ascorbate accumulation.

  7. A major facilitator superfamily transporter plays a dual role in polar auxin transport and drought stress tolerance in Arabidopsis.

    Science.gov (United States)

    Remy, Estelle; Cabrito, Tânia R; Baster, Pawel; Batista, Rita A; Teixeira, Miguel C; Friml, Jiri; Sá-Correia, Isabel; Duque, Paula

    2013-03-01

    Many key aspects of plant development are regulated by the polarized transport of the phytohormone auxin. Cellular auxin efflux, the rate-limiting step in this process, has been shown to rely on the coordinated action of PIN-formed (PIN) and B-type ATP binding cassette (ABCB) carriers. Here, we report that polar auxin transport in the Arabidopsis thaliana root also requires the action of a Major Facilitator Superfamily (MFS) transporter, Zinc-Induced Facilitator-Like 1 (ZIFL1). Sequencing, promoter-reporter, and fluorescent protein fusion experiments indicate that the full-length ZIFL1.1 protein and a truncated splice isoform, ZIFL1.3, localize to the tonoplast of root cells and the plasma membrane of leaf stomatal guard cells, respectively. Using reverse genetics, we show that the ZIFL1.1 transporter regulates various root auxin-related processes, while the ZIFL1.3 isoform mediates drought tolerance by regulating stomatal closure. Auxin transport and immunolocalization assays demonstrate that ZIFL1.1 indirectly modulates cellular auxin efflux during shootward auxin transport at the root tip, likely by regulating plasma membrane PIN2 abundance. Finally, heterologous expression in yeast revealed that ZIFL1.1 and ZIFL1.3 share H(+)-coupled K(+) transport activity. Thus, by determining the subcellular and tissue distribution of two isoforms, alternative splicing dictates a dual function for the ZIFL1 transporter. We propose that this MFS carrier regulates stomatal movements and polar auxin transport by modulating potassium and proton fluxes in Arabidopsis cells.

  8. Transgenic Arabidopsis expressing osmolyte glycine betaine synthesizing enzymes from halophilic methanogen promote tolerance to drought and salt stress.

    Science.gov (United States)

    Lai, Shu-Jung; Lai, Mei-Chin; Lee, Ren-Jye; Chen, Yu-Hsuan; Yen, Hungchen Emilie

    2014-07-01

    Glycine betaine (betaine) has the highest cellular osmoprotective efficiency which does not accumulate in most glycophytes. The biosynthetic pathway for betaine in higher plants is derived from the oxidation of low-accumulating metabolite choline that limiting the ability of most plants to produce betaine. Halophilic methanoarchaeon Methanohalophilus portucalensis FDF1(T) is a model anaerobic methanogen to study the acclimation of water-deficit stresses which de novo synthesize betaine by the stepwise methylation of glycine, catalyzed by glycine sarcosine N-methyltransferase (GSMT) and sarcosine dimethylglycine N-methyltransferase. In this report, genes encoding these betaine biosynthesizing enzymes, Mpgsmt and Mpsdmt, were introduced into Arabidopsis. The homozygous Mpgsmt (G), Mpsdmt (S), and their cross, Mpgsmt and Mpsdmt (G × S) plants showed increased accumulation of betaine. Water loss from detached leaves was slower in G, S, and G × S lines than wild-type (WT). Pot-grown transgenic plants showed better growth than WT after 9 days of withholding water or irrigating with 300 mM NaCl. G, S, G × S lines also maintained higher relative water content and photosystem II activity than WT under salt stress. This suggests heterologously expressed Mpgsmt and Mpsdmt could enhance tolerance to drought and salt stress in Arabidopsis. We also found a twofold increase in quaternary ammonium compounds in salt-stressed leaves of G lines, presumably due to the activation of GSMT activity by high salinity. This study demonstrates that introducing stress-activated enzymes is a way of avoiding the divergence of primary metabolites under normal growing conditions, while also providing protection in stressful environments.

  9. Two P5CS genes from common bean exhibiting different tolerance to salt stress in transgenic Arabidopsis

    Indian Academy of Sciences (India)

    Ji Bao Chen; Jian Wei Yang; Zhao Yuan Zhang; Xiao Fan Feng; Shu Min Wang

    2013-12-01

    Many plants accumulate proline in response to salt stress. -pyrroline-5-carboxylate synthetase (P5CS) is the rate-limiting enzyme in proline biosynthesis in plants. Plasmid DNA (pCHF3-PvP5CS1 and pCHF3-PvP5CS2) containing the selectable neomycin phosphotransferase gene for kanamycin resistance and Phaseolus vulgaris P5CS (PvP5CS1 and PvP5CS2) cDNA was introduced into Arabidopsis plants using Agrobacterium-mediated gene transfer. Southern blot, northern blot and RT-PCR analyses demonstrated that the foreign genes were integrated into Arabidopsis chromosomal DNA and expressed. Single-gene transformants were analysed in this study. Transgenic plants expressed higher levels of PvP5CS1 and PvP5CS2 transcripts under salt stress conditions than under normal conditions. When treated with 0, 100 and 200 mM NaCl, the average proline content in leaves of transgenic plants was significantly higher $(P \\lt 0.01)$ than control plants. The average relative electrical conductivity (REC) of transgenic lines was significantly lower $(P \\lt 0.01)$ than control plants under salt stress condition. Biomass production of transgenic lines was significantly higher $(P \\lt 0.05)$ than control plants under 200 mM NaCl stress treatment. These results indicated that introducing PvP5CS1 and PvP5CS2 cDNA into transgenic Arabidopsis caused proline overproduction, increasing salt tolerance. Although the expression of PvP5CS1 in L4 lines and PvP5CS2 in S4 lines was the same under salt stress condition, the S4 lines accumulated 1.6 and 1.9 times more proline than the L4 lines under 100 and 200 mM NaCl treatments, respectively. The REC of S4 plants was 0.5 (100 mM NaCl) and 0.6 times (200 mM NaCl) that of L4 plants. The biomass production of S4 plants was 1.6 times (200 mM NaCl) more than in L4 plants. Total P5CS enzyme activity of S4 was significantly higher than that of L4. These results implied that the PvP5CS2 protein had stronger capacity to catalyze proline synthesis than PvP5CS1 under salt

  10. A Novel Non-coding RNA Regulates Drought Stress Tolerance in Arabidopsis thaliana

    KAUST Repository

    Albesher, Nour H.

    2014-05-01

    Drought (soil water deficit) as a major adverse environmental condition can result in serious reduction in plant growth and crop production. Plants respond and adapt to drought stresses by triggering various signalling pathways leading to physiological, metabolic and developmental changes that may ultimately contribute to enhanced tolerance to the stress. Here, a novel non-coding RNA (ncRNA) involved in plant drought stress tolerance was identified. We showed that increasing the expression of this ncRNA led to enhanced sensitivity during seed germination and seedling growth to the phytohormone abscisic acid. The mutant seedlings are also more sensitive to osmotic stress inhibition of lateral root growth. Consistently, seedlings with enhanced expression of this ncRNA exhibited reduced transiprational water loss and were more drought-tolerant than the wild type. Future analyses of the mechanism for its role in drought tolerance may help us to understand how plant drought tolerance could be further regulated by this novel ncRNA.

  11. The Solanum lycopersicum Zinc Finger2 cysteine-2/histidine-2 repressor-like transcription factor regulates development and tolerance to salinity in tomato and Arabidopsis.

    Science.gov (United States)

    Hichri, Imène; Muhovski, Yordan; Žižkova, Eva; Dobrev, Petre I; Franco-Zorrilla, Jose Manuel; Solano, Roberto; Lopez-Vidriero, Irene; Motyka, Vaclav; Lutts, Stanley

    2014-04-01

    The zinc finger superfamily includes transcription factors that regulate multiple aspects of plant development and were recently shown to regulate abiotic stress tolerance. Cultivated tomato (Solanum lycopersicum Zinc Finger2 [SIZF2]) is a cysteine-2/histidine-2-type zinc finger transcription factor bearing an ERF-associated amphiphilic repression domain and binding to the ACGTCAGTG sequence containing two AGT core motifs. SlZF2 is ubiquitously expressed during plant development, and is rapidly induced by sodium chloride, drought, and potassium chloride treatments. Its ectopic expression in Arabidopsis (Arabidopsis thaliana) and tomato impaired development and influenced leaf and flower shape, while causing a general stress visible by anthocyanin and malonyldialdehyde accumulation. SlZF2 enhanced salt sensitivity in Arabidopsis, whereas SlZF2 delayed senescence and improved tomato salt tolerance, particularly by maintaining photosynthesis and increasing polyamine biosynthesis, in salt-treated hydroponic cultures (125 mm sodium chloride, 20 d). SlZF2 may be involved in abscisic acid (ABA) biosynthesis/signaling, because SlZF2 is rapidly induced by ABA treatment and 35S::SlZF2 tomatoes accumulate more ABA than wild-type plants. Transcriptome analysis of 35S::SlZF2 revealed that SlZF2 both increased and reduced expression of a comparable number of genes involved in various physiological processes such as photosynthesis, polyamine biosynthesis, and hormone (notably ABA) biosynthesis/signaling. Involvement of these different metabolic pathways in salt stress tolerance is discussed.

  12. EFFECTS OF SODIUM NITROPRUSSIDE ON SALT STRESS TOLERANCE OF TOCOPHEROL-DEFICIENT ARABIDOPSIS THALIANA PLANTS

    Directory of Open Access Journals (Sweden)

    Nadiia Mosiichuk

    2015-05-01

    Full Text Available In the present study, effects of exogenous sodium nitroprusside (SNP, a nitric oxide (•NO donor, on lipid peroxidation and antioxidant enzyme activities in wild type and tocopherol-deficient lines vte1 and vte4 of Arabidopsis thaliana subjected to 200 mM NaCl were studied. In wild type plants, pretreatment with SNP did not change level of thiobarbituric acid reactive substances (TBARS, but decreased the activities of dehydroascorbate reductase and guaiacol peroxidase under salt stress. In mutant line vte1, which lacks all forms of tocopherols, pretreatment with SNP reduced TBARS level and increases the activities of glutathione reductase and guaiacol peroxidase under salt stress. Ascorbate peroxidase activity decreased under salt stress conditions in both mutant lines, pretreated with SNP. It can be concluded, that pretreatment with SNP could attenuate salt-induced injuries in A. thaliana plants via up-regulation of activity of antioxidant enzymes and attenuate lipid peroxidation.

  13. Proteomics Analysis Reveals Post-Translational Mechanisms for Cold-Induced Metabolic Changes in Arabidopsis

    Institute of Scientific and Technical Information of China (English)

    Tian Li; Alma L.Burlingame; Zhi-Ping Deng; Zhi Yong Wang; Shou-Ling Xu; Juan A.Oses-Prieto; Sunita Putil; Peng Xu; Rui-Ju Wang; Kathy H.Li; David A.Malty; Liz-He An

    2011-01-01

    Cold-induced changes of gene expression and metabolism are critical for plants to survive freezing. Largely by changing gene expression, exposure to a period of non-freezing low temperatures increases plant tolerance to freezing-a phenomenon known as cold acclimation. Cold also induces rapid metabolic changes, which provide instant protection before temperature drops below freezing point. The molecular mechanisms for such rapid metabolic responses to cold remain largely unknown. Here, we use two-dimensional difference gel electrophoresis (2-D DIGE) analysis of sub-cellular fractions of Arabidopsis thaliana proteome coupled with spot identification by tandem mass spectrometry to identify early cold-responsive proteins in Arabidopsis. These proteins include four enzymes involved in starch degradation, three HSP100 proteins, several proteins in the tricarboxylic acid cycle, and sucrose metabolism. Upon cold treatment, the Disproportionating Enzyme 2 (DPE2), a cytosolic transglucosidase metabolizing maltose to glucose, increased rapidly in the centrifugation pellet fraction and decreased in the soluble fraction. Consistent with cold-induced inactivation of DPE2 enzymatic activity, the dpe2 mutant showed increased freezing tolerance without affecting the C-repeat binding transcription factor (CBF) transcriptional pathway. These results support a model that cold-induced inactivation of DPE2 leads to rapid accumulation of maltose, which is a cold-induced compatible solute that protects cells from freezing damage. This study provides evidence for a key role of rapid post-translational regulation of carbohydrate metabolic enzymes in plant protection against sudden temperature drop.

  14. Heterologous expression of type I antifreeze peptide GS-5 in baker's yeast increases freeze tolerance and provides enhanced gas production in frozen dough.

    Science.gov (United States)

    Panadero, Joaquin; Randez-Gil, Francisca; Prieto, Jose Antonio

    2005-12-28

    The demand for frozen-dough products has increased notably in the baking industry. Nowadays, no appropriate industrial baker's yeast with optimal gassing capacity in frozen dough is, however, available, and it is unlikely that classical breeding programs could provide significant improvements of this trait. Antifreeze proteins, found in diverse organisms, display the ability to inhibit the growth of ice, allowing them to survive at temperatures below 0 degrees C. In this study a recombinant antifreeze peptide GS-5 was expressed from the polar fish grubby sculpin (Myoxocephalus aenaeus) in laboratory and industrial baker's yeast strains of Saccharomyces cerevisiae. Production of the recombinant protein increased freezing tolerance in both strains tested. Furthermore, expression of the GS-5 encoding gene enhanced notably the gassing rate and total gas production in frozen and frozen sweet doughs. These effects are unlikely to be due to reduced osmotic damage during freezing/thawing, because recombinant cells showed growth behavior similar to that of the parent under hypermosmotic stress conditions.

  15. ICE1 Ser403 is necessary for protein stabilization and regulation of cold signaling and tolerance

    OpenAIRE

    Miura, Kenji; Ohta, Masaru; Nakazawa, Machiko; Ono, Michiyuki; Hasegawa, Paul M.

    2011-01-01

    ICE1, a MYC-type transcription factor, has an important role in the induction of CBF3/DREB1A for regulation of cold signaling and tolerance. Here we reveal that serine 403 of ICE1 is involved in regulating the transactivation and stability of the ICE1 protein. Substitution of serine 403 by alanine enhanced the transactivational activity of ICE1 in Arabidopsis protoplasts. Over-expression of ICE1(S403A) conferred more freezing tolerance than ICE1(WT) in Arabidopsis, and the expression of cold-...

  16. Chloroplast targeting of phytochelatin synthase in Arabidopsis: effects on heavy metal tolerance and accumulation.

    Science.gov (United States)

    Picault, N; Cazalé, A C; Beyly, A; Cuiné, S; Carrier, P; Luu, D T; Forestier, C; Peltier, G

    2006-11-01

    The enzymatically synthesized thiol peptide phytochelatin (PC) plays a central role in heavy metal tolerance and detoxification in plants. In response to heavy metal exposure, the constitutively expressed phytochelatin synthase enzyme (PCS) is activated leading to synthesis of PCs in the cytosol. Recent attempts to increase plant metal accumulation and tolerance reported that PCS over-expression in transgenic plants paradoxically induced cadmium hypersensitivity. In the present paper, we investigate the possibility of synthesizing PCs in plastids by over-expressing a plastid targeted phytochelatin synthase (PCS). Plastids represent a relatively important cellular volume and offer the advantage of containing glutathione, the precursor of PC synthesis. Using a constitutive CaMV 35S promoter and a RbcS transit peptide, we successfully addressed AtPCS1 to chloroplasts, significant PCS activity being measured in this compartment in two independent transgenic lines. A substantial increase in the PC content and a decrease in the glutathione pool were observed in response to cadmium exposure, when compared to wild-type plants. While over-expressing AtPCS1 in the cytosol importantly decreased cadmium tolerance, both cadmium tolerance and accumulation of plants expressing plastidial AtPCS1 were not significantly affected compared to wild-type. Interestingly, targeting AtPCS1 to chloroplasts induced a marked sensitivity to arsenic while plants over-expressing AtPCS1 in the cytoplasm were more tolerant to this metalloid. These results are discussed in relation to heavy metal trafficking pathways in higher plants and to the interest of using plastid expression of PCS for biotechnological applications.

  17. High-Throughput Non-destructive Phenotyping of Traits that Contribute to Salinity Tolerance in Arabidopsis thaliana

    KAUST Repository

    Awlia, Mariam

    2016-09-28

    Reproducible and efficient high-throughput phenotyping approaches, combined with advances in genome sequencing, are facilitating the discovery of genes affecting plant performance. Salinity tolerance is a desirable trait that can be achieved through breeding, where most have aimed at selecting for plants that perform effective ion exclusion from the shoots. To determine overall plant performance under salt stress, it is helpful to investigate several plant traits collectively in one experimental setup. Hence, we developed a quantitative phenotyping protocol using a high-throughput phenotyping system, with RGB and chlorophyll fluorescence (ChlF) imaging, which captures the growth, morphology, color and photosynthetic performance of Arabidopsis thaliana plants in response to salt stress. We optimized our salt treatment by controlling the soil-water content prior to introducing salt stress. We investigated these traits over time in two accessions in soil at 150, 100, or 50 mM NaCl to find that the plants subjected to 100 mM NaCl showed the most prominent responses in the absence of symptoms of severe stress. In these plants, salt stress induced significant changes in rosette area and morphology, but less prominent changes in rosette coloring and photosystem II efficiency. Clustering of ChlF traits with plant growth of nine accessions maintained at 100 mM NaCl revealed that in the early stage of salt stress, salinity tolerance correlated with non-photochemical quenching processes and during the later stage, plant performance correlated with quantum yield. This integrative approach allows the simultaneous analysis of several phenotypic traits. In combination with various genetic resources, the phenotyping protocol described here is expected to increase our understanding of plant performance and stress responses, ultimately identifying genes that improve plant performance in salt stress conditions.

  18. Over-expression of an Arabidopsis δ-OAT gene enhances salt and drought tolerance in transgenic rice

    Institute of Scientific and Technical Information of China (English)

    WU Liangqi; FAN Zhanmin; GUO Lei; LI Yongqing; ZHANG Wenjing; QU Li-Jia; CHEN Zhangliang

    2003-01-01

    δ-OAT, ornithine-δ-aminotransferase, is the key enzyme involved in proline biosynthesis. In this study the Arabidopsisδ-OAT gene was transferred into rice (Oryza sativa L. ssp japonica cv. Zhongzuo 321), whose successful integration was demonstrated by PCR and Southern blot analysis. The over-expression of the gene in transgenic rice was also confirmed. Biochemical analysis showed that, under salt or drought stress conditions, proline contents in the leaves and roots in transgenic rice plants were 5- to 15-fold of those in non-transgenic controls. Under stress conditions, germinating rate of transgenic lines is higher than that of controls. Although the growth of rice plants tested were more and more retarded with the increasing of NaCl concentration, the transgenic plants grow faster compared to the controls under the same stress condition. Meanwhile, the resistance to KCl and MgSO4 stresses was also found enhanced in transgenic rice. Furthermore, the over-expression ofδ-OAT also improved the yield of transgenic plants under stress conditions. The average yield per plant of transgenic lines increases about 12%-41% more than that of control lines under 0.1 mol/L NaCl stress. These data indicated that the over-expression of δ-OAT, with the accumulation of proline, resulted in the enhancement of salt and drought tolerance and an increase of rice yield, which is of significance in agriculture.

  19. Divergent regulation of CBF regulon on cold tolerance and plant phenotype in cassava overexpressing Arabidopsis CBF3 gene

    Directory of Open Access Journals (Sweden)

    Dong An

    2016-12-01

    Full Text Available Cassava is a tropical origin plant that is sensitive to chilling stress. In order to understand the CBF cold response pathway, a well-recognized regulatory mechanism in temperate plants, in cassava, overexpression of an Arabidopsis CBF3 gene is studied. This gene renders cassava increasingly tolerant to cold and drought stresses but is associated with retarded plant growth, leaf curling, reduced storage root yield, and reduced anthocyanin accumulation in a transcript abundance-dependent manner. Physiological analysis revealed that the transgenic cassava increased proline accumulation, reduced malondialdehyde production, and electrolyte leakage under cold stress. These transgenic lines also showed high relative water content when faced with drought. The expression of partial CBF-targeted genes in response to cold displayed temporal and spatial variations in the wild-type and transgenic plants: highly inducible in leaves and less altered in apical buds. In addition, anthocyanin accumulation was inhibited by downregulating the expression of genes involved in its biosynthesis and by interplaying between the CBF3 and the endogenous transcription factors. Thus, the heterologous CBF3 modulates the expression of stress-related genes and carries out a series of physiological adjustments under stressful conditions, showing a varied regulation pattern of CBF regulon from that of cassava CBFs.

  20. The plant cuticle is required for osmotic stress regulation of abscisic acid biosynthesis and osmotic stress tolerance in Arabidopsis

    KAUST Repository

    Wang, Zhenyu

    2011-05-01

    Osmotic stress activates the biosynthesis of abscisic acid (ABA). One major step in ABA biosynthesis is the carotenoid cleavage catalyzed by a 9-cis epoxycarotenoid dioxygenase (NCED). To understand the mechanism for osmotic stress activation of ABA biosynthesis, we screened for Arabidopsis thaliana mutants that failed to induce the NCED3 genee xpression in response to osmotic stress treatments. The ced1 (for 9-cis epoxycarotenoid dioxy genase defective 1) mutant isolated in this study showed markedly reduced expression of NCED3 in response to osmotic stress (polyethylene glycol)treatments compared with the wild type. Other ABA biosynthesis genes are also greatly reduced in ced1 under osmotic stress. ced1 mutant plants are very sensitive to even mild osmotic stress. Map-based cloning revealed unexpectedly thatCED1 encodes a putative a/b hydrolase domain-containing protein and is allelic to the BODYGUARD gene that was recently shown to be essential for cuticle biogenesis. Further studies discovered that other cut in biosynthesis mutants are also impaired in osmotic stress induction of ABA biosynthesis genes and are sensitive to osmotic stress. Our work demonstrates that the cuticle functions not merely as a physical barrier to minimize water loss but also mediates osmotic stress signaling and tolerance by regulating ABA biosynthesis and signaling. © 2011 American Society of Plant Biologists. All rights reserved.

  1. Plastid ribosomal protein S5 is involved in photosynthesis, plant development, and cold stress tolerance in Arabidopsis.

    Science.gov (United States)

    Zhang, Junxiang; Yuan, Hui; Yang, Yong; Fish, Tara; Lyi, Sangbom M; Thannhauser, Theodore W; Zhang, Lugang; Li, Li

    2016-04-01

    Plastid ribosomal proteins are essential components of protein synthesis machinery and have diverse roles in plant growth and development. Mutations in plastid ribosomal proteins lead to a range of developmental phenotypes in plants. However, how they regulate these processes is not fully understood, and the functions of some individual plastid ribosomal proteins remain unknown. To identify genes responsible for chloroplast development, we isolated and characterized a mutant that exhibited pale yellow inner leaves with a reduced growth rate in Arabidopsis. The mutant (rps5) contained a missense mutation of plastid ribosomal protein S5 (RPS5), which caused a dramatically reduced abundance of chloroplast 16S rRNA and seriously impaired 16S rRNA processing to affect ribosome function and plastid translation. Comparative proteomic analysis revealed that the rps5 mutation suppressed the expression of a large number of core components involved in photosystems I and II as well as many plastid ribosomal proteins. Unexpectedly, a number of proteins associated with cold stress responses were greatly decreased in rps5, and overexpression of the plastid RPS5 improved plant cold stress tolerance. Our results indicate that RPS5 is an important constituent of the plastid 30S subunit and affects proteins involved in photosynthesis and cold stress responses to mediate plant growth and development.

  2. Arsenic and mercury tolerance and cadmium sensitivity in Arabidopsis plants expressing bacterial gamma-glutamylcysteine synthetase.

    Science.gov (United States)

    Li, Yujing; Dhankher, Om Parkash; Carreira, Laura; Balish, Rebecca S; Meagher, Richard B

    2005-06-01

    Cysteine sulfhydryl-rich peptide thiols are believed to play important roles in the detoxification of many heavy metals and metalloids such as arsenic, mercury, and cadmium in plants. The gamma-glutamylcysteine synthetase (gamma-ECS) catalyzes the synthesis of the dipeptidethiol gamma-glu-cys (gamma-EC), the first step in the biosynthesis of phytochelatins (PCs). Arabidopsis thaliana, engineered to express the bacterial gamma-ECS gene under control of a strong constitutive actin regulatory sequence (A2), expressed gamma-ECS at levels approaching 0.1% of total protein. In response to arsenic, mercury, and cadmium stresses, the levels of gamma-EC and its derivatives, glutathione (GSH) and PCs, were increased in the A2::ECS transgenic plants to three- to 20-fold higher concentrations than the increases that occurred in wild-type (WT). Compared to cadmium and mercury treatments, arsenic treatment most significantly increased levels of gamma-EC and PCs in both the A2::ECS transgenic and WT plants. The A2::ECS transgenic plants were highly resistant to arsenic and weakly resistant to mercury. Although exposure to cadmium produced three- to fivefold increases in levels of gamma-EC-related peptides in the A2::ECS lines, these plants were significantly more sensitive to Cd(II) than WT and trace levels of Cd(II) blocked resistance to arsenic and mercury. A few possible mechanisms for gamma-ECS-enhanced arsenic and mercury resistance and cadmium hypersensitivity are discussed.

  3. Does acute led (Pb) contamination influence membrane fatty acid composition and freeze tolerance in intertidal blue mussels in arctic Greenland?

    DEFF Research Database (Denmark)

    Thyrring, Jakob; Juhl, Bodil Klein; Holmstrup, Martin;

    2015-01-01

    In their natural habitats, organisms are exposed to multiple stressors. Heavy metal contamination stresses the cell membrane due to increased peroxidation of lipids. Likewise, sub-zero air temperatures potentially reduce membrane functionality in ectothermal animals. We tested if acute lead (Pb...... tolerance and does not induce membrane damage in terms of persistent lipid peroxidation....

  4. Overexpressing GSH1 and AsPCS1 simultaneously increases the tolerance and accumulation of cadmium and arsenic in Arabidopsis thaliana.

    Science.gov (United States)

    Guo, Jiangbo; Dai, Xiaojing; Xu, Wenzhong; Ma, Mi

    2008-07-01

    The goal of this study was to develop transgenic plants with increased tolerance for and accumulation of heavy metals and metalloids from soil by simultaneous overexpression of AsPCS1 and GSH1 (derived from garlic and baker's yeast) in Arabidopsis thaliana. Phytochelatins (PCs) and glutathione (GSH) are the main binding peptides involved in chelating heavy metal ions in plants and other living organisms. Single-gene transgenic lines had higher tolerance to and accumulated more Cd and As than wild-type. Compared to single-gene transgenic lines, dual-gene transformants exhibited significantly higher tolerance to and accumulated more Cd and As. One of the dual-gene transgenic lines, PG1, accumulated twice the amount of Cd as single-gene transgenic lines. Simultaneous overexpression of AsPCS1 and GSH1 led to elevated total PC production in transgenic Arabidopsis. These results indicate that such a stacking of modified genes is capable of increasing Cd and As tolerance and accumulation in transgenic lines, and represents a highly promising new tool for use in phytoremediation efforts.

  5. Heterologous expression of a chloroplast outer envelope protein from Suaeda salsa confers oxidative stress tolerance and induces chloroplast aggregation in transgenic Arabidopsis plants.

    Science.gov (United States)

    Wang, Fang; Yang, Chun-Lin; Wang, Li-Li; Zhong, Nai-Qin; Wu, Xiao-Min; Han, Li-Bo; Xia, Gui-Xian

    2012-03-01

    Suaeda salsa is a euhalophytic plant that is tolerant to coastal seawater salinity. In this study, we cloned a cDNA encoding an 8.4 kDa chloroplast outer envelope protein (designated as SsOEP8) from S. salsa and characterized its cellular function. Steady-state transcript levels of SsOEP8 in S. salsa were up-regulated in response to oxidative stress. Consistently, ectopic expression of SsOEP8 conferred enhanced oxidative stress tolerance in transgenic Bright Yellow 2 (BY-2) cells and Arabidopsis, in which H(2) O(2) content was reduced significantly in leaf cells. Further studies revealed that chloroplasts aggregated to the sides of mesophyll cells in transgenic Arabidopsis leaves, and this event was accompanied by inhibited expression of genes encoding proteins for chloroplast movements such as AtCHUP1, a protein involved in actin-based chloroplast positioning and movement. Moreover, organization of actin cytoskeleton was found to be altered in transgenic BY-2 cells. Together, these results suggest that SsOEP8 may play a critical role in oxidative stress tolerance by changing actin cytoskeleton-dependent chloroplast distribution, which may consequently lead to the suppressed production of reactive oxygen species (ROS) in chloroplasts. One significantly novel aspect of this study is the finding that the small chloroplast envelope protein is involved in oxidative stress tolerance.

  6. AtHsfA2 modulates expression of stress responsive genes and enhances tolerance to heat and oxidative stress in Arabidopsis

    Institute of Scientific and Technical Information of China (English)

    LI; Chunguang; CHEN; Qijun; GAO; Xinqi; QI; Bishu; CHEN; Na

    2005-01-01

    There is increasing evidence for considerable interlinking between the responses to heat stress and oxidative stress, and recent researches suggest heat shock transcription factors (Hsfs) play an important role in linking heat shock with oxidative stress signals. In this paper, we present evidence that AtHsfA2 modulated expression of stress responsive genes and enhanced tolerance to heat and oxidative stress in Arabidopsis. Using Northern blot and quantitative RT-PCR analysis, we demonstrated that the expression of AtHsfA2 was induced by not only HS but also oxidative stress. By functional analysis of AtHsfA2 knockout mutants and AtHsfA2 overexpressing transgenic plants, we also demonstrated that the mutants displayed reduced the basal and acquired thermotolerance as well as oxidative stress tolerance but the overexpression lines displayed increased tolerance to these stress. The phenotypes correlated with the expression of some Hsps and APX1, ion leakage, H2O2 level and degree of oxidative injuries. These results showed that, by modulated expression of stress responsive genes, AtHsfA2 enhanced tolerance to heat and oxidative stress in Arabidopsis. So we suggest that AtHsfA2 plays an important role in linking heat shock with oxidative stress signals.

  7. A G-protein β subunit, AGB1, negatively regulates the ABA response and drought tolerance by down-regulating AtMPK6-related pathway in Arabidopsis.

    Directory of Open Access Journals (Sweden)

    Dong-bei Xu

    Full Text Available Heterotrimeric G-proteins are versatile regulators involved in diverse cellular processes in eukaryotes. In plants, the function of G-proteins is primarily associated with ABA signaling. However, the downstream effectors and the molecular mechanisms in the ABA pathway remain largely unknown. In this study, an AGB1 mutant (agb1-2 was found to show enhanced drought tolerance, indicating that AGB1 might negatively regulate drought tolerance in Arabidopsis. Data showed that AGB1 interacted with protein kinase AtMPK6 that was previously shown to phosphorylate AtVIP1, a transcription factor responding to ABA signaling. Our study found that transcript levels of three ABA responsive genes, AtMPK6, AtVIP1 and AtMYB44 (downstream gene of AtVIP1, were significantly up-regulated in agb1-2 lines after ABA or drought treatments. Other ABA-responsive and drought-inducible genes, such as RD29A (downstream gene of AtMYB44, were also up-regulated in agb1-2 lines. Furthermore, overexpression of AtVIP1 resulted in hypersensitivity to ABA at seed germination and seedling stages, and significantly enhanced drought tolerance in transgenic plants. These results suggest that AGB1 was involved in the ABA signaling pathway and drought tolerance in Arabidopsis through down-regulating the AtMPK6, AtVIP1 and AtMYB44 cascade.

  8. A G-protein β subunit, AGB1, negatively regulates the ABA response and drought tolerance by down-regulating AtMPK6-related pathway in Arabidopsis.

    Science.gov (United States)

    Xu, Dong-bei; Chen, Ming; Ma, Ya-nan; Xu, Zhao-shi; Li, Lian-cheng; Chen, Yao-feng; Ma, You-zhi

    2015-01-01

    Heterotrimeric G-proteins are versatile regulators involved in diverse cellular processes in eukaryotes. In plants, the function of G-proteins is primarily associated with ABA signaling. However, the downstream effectors and the molecular mechanisms in the ABA pathway remain largely unknown. In this study, an AGB1 mutant (agb1-2) was found to show enhanced drought tolerance, indicating that AGB1 might negatively regulate drought tolerance in Arabidopsis. Data showed that AGB1 interacted with protein kinase AtMPK6 that was previously shown to phosphorylate AtVIP1, a transcription factor responding to ABA signaling. Our study found that transcript levels of three ABA responsive genes, AtMPK6, AtVIP1 and AtMYB44 (downstream gene of AtVIP1), were significantly up-regulated in agb1-2 lines after ABA or drought treatments. Other ABA-responsive and drought-inducible genes, such as RD29A (downstream gene of AtMYB44), were also up-regulated in agb1-2 lines. Furthermore, overexpression of AtVIP1 resulted in hypersensitivity to ABA at seed germination and seedling stages, and significantly enhanced drought tolerance in transgenic plants. These results suggest that AGB1 was involved in the ABA signaling pathway and drought tolerance in Arabidopsis through down-regulating the AtMPK6, AtVIP1 and AtMYB44 cascade.

  9. Cryobehavior of the plasma membrane in protoplasts isolated from cold-acclimated Arabidopsis leaves is related to surface area regulation.

    Science.gov (United States)

    Yamazaki, Tomokazu; Kawamura, Yukio; Uemura, Matsuo

    2008-06-01

    Extracellular freezing in plants results in dehydration and mechanical stresses upon the plasma membrane. Plants that acquire enhanced freezing tolerance after cold acclimation can withstand these two physical stresses. To understand the tolerance to freeze-induced physical stresses, the cryobehavior of the plasma membrane was observed using protoplasts isolated from cold-acclimated Arabidopsis thaliana leaves with the combination of a lipophilic fluorescent dye FM 1-43 and cryomicroscopy. We found that many vesicular structures appeared in the cytoplasmic region near the plasma membrane just after extracellular freezing occurred. These structures, referred to as freeze-induced vesicular structures (FIVs), then developed horizontally near the plasma membrane during freezing. There was a strong correlation between the increase in individual FIV size and the decrease in the surface area of the protoplasts during freezing. Some FIVs fused with their neighbors as the temperature decreased. Occasionally, FIVs fused with the plasma membrane, which may be necessary to relax the stress upon the plasma membrane during freezing. Vesicular structures resembling FIVs were also induced when protoplasts were mechanically pressed between a coverslip and slide glass. Fewer FIVs formed when protoplasts were subjected to hyperosmotic solution, suggesting that FIV formation is associated with mechanical stress rather than dehydration. Collectively, these results suggest that cold-acclimated plant cells may balance membrane tension in the plasma membrane by regulating the surface area. This enables plant cells to withstand the direct mechanical stress imposed by extracellular freezing.

  10. Soybean GmPHD-Type Transcription Regulators Improve Stress Tolerance in Transgenic Arabidopsis Plants

    OpenAIRE

    Wei Wei; Jian Huang; Yu-Jun Hao; Hong-Feng Zou; Hui-Wen Wang; Jing-Yun Zhao; Xue-Yi Liu; Wan-Ke Zhang; Biao Ma; Jin-Song Zhang; Shou-Yi Chen

    2009-01-01

    BACKGROUND: Soybean [Glycine max (L.) Merr.] is one of the most important crops for oil and protein resource. Improvement of stress tolerance will be beneficial for soybean seed production. PRINCIPAL FINDINGS: Six GmPHD genes encoding Alfin1-type PHD finger protein were identified and their expressions differentially responded to drought, salt, cold and ABA treatments. The six GmPHDs were nuclear proteins and showed ability to bind the cis-element "GTGGAG". The N-terminal domain of GmPHD play...

  11. Assessment of Freezing Tolerance of Juglans Germplasms by Using Annual Dormant Branches%核桃属植物休眠期的抗寒性鉴定

    Institute of Scientific and Technical Information of China (English)

    田景花; 王红霞; 高仪; 张志华

    2013-01-01

    The test materials were annual dormant branches of 18 Juglans germplasms that belong to 4 species including J.regia L.,J.hopeiensis Hu.,J.mandshurica Maxim.,and J.nigra L.The semi-lethal temperatures (LTs0) were assessed separately by electrolyte leakage,tissue browning,and triphenyl tetrazolium chloride (TTC) dyeing method with Logistic equation.Branch anatomical structures were observed with paraffin sections.The correlations between branch anatomical structures and freezing tolerance were analyzed.The results showed that relative electrical conductivities (REC) of walnut annual branches were rising with the temperature drop.The significant differences of LTs0 of Juglans germplasms were observed between-38 ℃ and-22 ℃.The interspecific differences were distinct,and the order of freezing tolerance was J.nigra > J.mandshurica,J.hopeiensis > J.regia.Electrolyte leakage,tissuebrowning,and TTC dyeing method all could be used for assessment of the freezing tolerance in dormant period,but LT50 assessed by electrolyte leakage was more accurate than the other methods.There was significant positive correlation (P < 0.01) between LT50 and REC at-24 ℃,which was a little higher than LT50 of the most Juglans germplasms.LT50 and REC at-24 ℃ could be used as physicochemical indexes for freezing tolerance identification of Juglans in dormant period.In addition,the tissues thickness of annual branches with roughly similar stem diameter had significant differences.The significant negative correlation (P < 0.01) was showed between LT50 and phellem layer thickness or phellem layer ratio in the branch,which provided morphological indexes to assess the freezing tolerance of Juglans in dormant period.%以核桃属(Juglans)中的普通核桃、核桃楸、河北核桃和黑核桃4个种的18份种质休眠期的1年生枝条为试验材料,采用电解质渗出率法、组织褐变法及氯化三苯基四氮唑(TTC)染色法并配合Logistic方程确定枝

  12. Redox regulation of ascorbate and glutathione by a chloroplastic dehydroascorbate reductase is required for high-light stress tolerance in Arabidopsis.

    Science.gov (United States)

    Noshi, Masahiro; Hatanaka, Risa; Tanabe, Noriaki; Terai, Yusuke; Maruta, Takanori; Shigeoka, Shigeru

    2016-05-01

    Chloroplasts are a significant site for reactive oxygen species production under illumination and, thus, possess a well-organized antioxidant system involving ascorbate. Ascorbate recycling occurs in different manners in this system, including a dehydroascorbate reductase (DHAR) reaction. We herein investigated the physiological significance of DHAR3 in photo-oxidative stress tolerance in Arabidopsis. GFP-fused DHAR3 protein was targeted to chloroplasts in Arabidopsis leaves. A DHAR3 knockout mutant exhibited sensitivity to high light (HL). Under HL, the ascorbate redox states were similar in mutant and wild-type plants, while total ascorbate content was significantly lower in the mutant, suggesting that DHAR3 contributes, at least to some extent, to ascorbate recycling. Activation of monodehydroascorbate reductase occurred in dhar3 mutant, which might compensate for the lack of DHAR3. Interestingly, glutathione oxidation was consistently inhibited in dhar3 mutant. These findings indicate that DHAR3 regulates both ascorbate and glutathione redox states to acclimate to HL.

  13. Increased biomass, seed yield and stress tolerance is conferred in Arabidopsis by a novel enzyme from the resurrection grass Sporobolus stapfianus that glycosylates the strigolactone analogue GR24.

    Directory of Open Access Journals (Sweden)

    Sharmin Islam

    Full Text Available Isolation of gene transcripts from desiccated leaf tissues of the resurrection grass, Sporobolus stapfianus, resulted in the identification of a gene, SDG8i, encoding a Group 1 glycosyltransferase (UGT. Here, we examine the effects of introducing this gene, under control of the CaMV35S promoter, into the model plant Arabidopsis thaliana. Results show that Arabidopsis plants constitutively over-expressing SDG8i exhibit enhanced growth, reduced senescence, cold tolerance and a substantial improvement in protoplasmic drought tolerance. We hypothesise that expression of SDG8i in Arabidopsis negatively affects the bioactivity of metabolite/s that mediate/s environmentally-induced repression of cell division and expansion, both during normal development and in response to stress. The phenotype of transgenic plants over-expressing SDG8i suggests modulation in activities of both growth- and stress-related hormones. Plants overexpressing the UGT show evidence of elevated auxin levels, with the enzyme acting downstream of ABA to reduce drought-induced senescence. Analysis of the in vitro activity of the UGT recombinant protein product demonstrates that SDG8i can glycosylate the synthetic strigolactone analogue GR24, evoking a link with strigolactone-related processes in vivo. The large improvements observed in survival of transgenic Arabidopsis plants under cold-, salt- and drought-stress, as well as the substantial increases in growth rate and seed yield under non-stress conditions, indicates that overexpression of SDG8i in crop plants may provide a novel means of increasing plant productivity.

  14. Functional and transcriptome analysis reveals an acclimatization strategy for abiotic stress tolerance mediated by Arabidopsis NF-YA family members.

    Science.gov (United States)

    Leyva-González, Marco Antonio; Ibarra-Laclette, Enrique; Cruz-Ramírez, Alfredo; Herrera-Estrella, Luis

    2012-01-01

    Nuclear Factor Y (NF-Y) is a heterotrimeric complex formed by NF-YA/NF-YB/NF-YC subunits that binds to the CCAAT-box in eukaryotic promoters. In contrast to other organisms, in which a single gene encodes each subunit, in plants gene families of over 10 members encode each of the subunits. Here we report that five members of the Arabidopsis thaliana NF-YA family are strongly induced by several stress conditions via transcriptional and miR169-related post-transcriptional mechanisms. Overexpression of NF-YA2, 7 and 10 resulted in dwarf late-senescent plants with enhanced tolerance to several types of abiotic stress. These phenotypes are related to alterations in sucrose/starch balance and cell elongation observed in NF-YA overexpressing plants. The use of transcriptomic analysis of transgenic plants that express miR169-resistant versions of NF-YA2, 3, 7, and 10 under an estradiol inducible system, as well as a dominant-repressor version of NF-YA2 revealed a set of genes, whose promoters are enriched in NF-Y binding sites (CCAAT-box) and that may be directly regulated by the NF-Y complex. This analysis also suggests that NF-YAs could participate in modulating gene regulation through positive and negative mechanisms. We propose a model in which the increase in NF-YA transcript levels in response to abiotic stress is part of an adaptive response to adverse environmental conditions in which a reduction in plant growth rate plays a key role.

  15. Effects of salt stress on wild type and vte4 mutant Arabidopsis thaliana: Model plant to engineer tolerance towards salinity

    Directory of Open Access Journals (Sweden)

    Khalatbari Amir Ali

    2013-01-01

    Full Text Available One of the major environmental constraints impairing plant distribution and yield is believed to be salt stress. Additionally, engineered abiotic stress resistance or/and tolerance is considered as an indispensable target in order to enhance plant productivity. In this study, the effects of salinity on physiological and morphological of wild type (Columbia-0 and vte4 mutant Arabidopsis thaliana were investigated under different NaCl concentrations. These salt treatments, including control condition, 50mM and 100mM NaCl were imposed on the plants. Each salt treatment was replicated three times in a complete randomized design with factorial arrangement. Wild type and mutant A.thaliana plants were subjected to the abiotic stress (salinity for up to 11 days to evaluate the parameters of growth, development and water relations. As a result, the performance of wild type plants was stronger than vte4 mutant under different salt treatments. Under control condition, rosette dry weight, maximum quantum efficiency (PSII and specific leaf area obtained the highest values of 13.85 mg, considered, wild type A.thaliana recorded higher value of 0.82 gW/gFW for relative water content (RWC under 50mM NaCl whereas mutant plants gained the value of 0.78 gW/gFW under the same condition. However, root mass fraction indicated an increase for both wild type and vte4 mutant plants after 11 days of salt stress onset. The reduction of water potential was observed for wild type and mutant A.thaliana where it scored -1.3 MPa and -1.4, respectively. As a conclusion, these findings implied that under different salt treatments morphological and physiological responses of wild type and vte4 mutant were affected in which wild type plants showed more tolerance. Lack of γ-tocopherol methyltransferase (γ -TMT gene in vte4 seemed to impair defence mechanism of this mutant against salinity.

  16. A novel Glycine soja tonoplast intrinsic protein gene responds to abiotic stress and depresses salt and dehydration tolerance in transgenic Arabidopsis thaliana.

    Science.gov (United States)

    Wang, Xi; Li, Yong; Ji, Wei; Bai, Xi; Cai, Hua; Zhu, Dan; Sun, Xiao-Li; Chen, Lian-Jiang; Zhu, Yan-Ming

    2011-07-15

    Tonoplast intrinsic protein (TIP) is a subfamily of the aquaporin (AQP), also known as major intrinsic protein (MIP) family, and regulates water movement across vacuolar membranes. Some reports have implied that TIP genes are associated with plant tolerance to some abiotic stresses that cause water loss, such as drought and high salinity. In our previous work, we found that an expressed sequence tag (EST) representing a TIP gene in our Glycine soja EST library was inducible by abiotic stresses. This TIP was subsequently isolated from G. soja with cDNA library screening, EST assembly and PCR, and named as GsTIP2;1. The expression patterns of GsTIP2;1 in G. soja under low temperature, salt and dehydration stress were different in leaves and roots. Though GsTIP2;1 is a stress-induced gene, overexpression of GsTIP2;1 in Arabidopsis thaliana depressed tolerance to salt and dehydration stress, but did not affect seedling growth under cold or favorable conditions. Higher dehydration speed was detected in Arabidopsis plants overexpressing GsTIP2;1, implying GsTIP2;1 might mediate stress sensitivity by enhancing water loss in the plant. Such a result is not identical to previous reports, providing some new information about the relationship between TIP and plant abiotic stress tolerance.

  17. MzPIP2;1: An Aquaporin Involved in Radial Water Movement in Both Water Uptake and Transportation, Altered the Drought and Salt Tolerance of Transgenic Arabidopsis.

    Directory of Open Access Journals (Sweden)

    Lin Wang

    Full Text Available Plants are unavoidably subjected to various abiotic stressors, including high salinity, drought and low temperature, which results in water deficit and even death. Water uptake and transportation play a critical role in response to these stresses. Many aquaporin proteins, localized at different tissues, function in various transmembrane water movements. We targeted at the key aquaporin in charge of both water uptake in roots and radial water transportation from vascular tissues through the whole plant.The MzPIP2;1 gene encoding a plasma membrane intrinsic protein was cloned from salt-tolerant apple rootstock Malus zumi Mats. The GUS gene was driven by MzPIP2;1 promoter in transgenic Arabidopsis. It indicated that MzPIP2;1 might function in the epidermal and vascular cells of roots, parenchyma cells around vessels through the stems and vascular tissues of leaves. The ectopically expressed MzPIP2;1 conferred the transgenic Arabidopsis plants enhanced tolerance to slight salt and drought stresses, but sensitive to moderate salt stress, which was indicated by root length, lateral root number, fresh weight and K+/Na+ ratio. In addition, the possible key cis-elements in response to salt, drought and cold stresses were isolated by the promoter deletion experiment.The MzPIP2;1 protein, as a PIP2 aquaporins subgroup member, involved in radial water movement, controls water absorption and usage efficiency and alters transgenic plants drought and salt tolerance.

  18. Overexpression of MpCYS4, A Phytocystatin Gene from Malus prunifolia (Willd.) Borkh., Enhances Stomatal Closure to Confer Drought Tolerance in Transgenic Arabidopsis and Apple.

    Science.gov (United States)

    Tan, Yanxiao; Li, Mingjun; Yang, Yingli; Sun, Xun; Wang, Na; Liang, Bowen; Ma, Fengwang

    2017-01-01

    Phytocystatins (PhyCys) comprise a group of inhibitors for cysteine proteinases in plants. They play a wide range of important roles in regulating endogenous processes and protecting plants against various environmental stresses, but the underlying mechanisms remain largely unknown. Here, we detailed the biological functions of MpCYS4, a member of cystatin genes isolated from Malus prunifolia. This gene was activated under water deficit, heat (40°C), exogenous abscisic acid (ABA), or methyl viologen (MV) (Tan et al., 2014a). At cellular level, MpCYS4 protein was found to be localized in the nucleus, cytoplasm, and plasma membrane of onion epidermal cells. Recombinant MpCYS4 cystatin expressed in Escherichia coli was purified and it exhibited cysteine protease inhibitor activity. Transgenic overexpression of MpCYS4 in Arabidopsis (Arabidopsis thaliana) and apple (Malus domestica) led to ABA hypersensitivity and series of ABA-associated phenotypes, such as enhanced ABA-induced stomatal closing, altered expression of many ABA/stress-responsive genes, and enhanced drought tolerance. Taken together, our results demonstrate that MpCYS4 is involved in ABA-mediated stress signal transduction and confers drought tolerance at least in part by enhancing stomatal closure and up-regulating the transcriptional levels of ABA- and drought-related genes. These findings provide new insights into the molecular mechanisms by which phytocystatins influence plant growth, development, and tolerance to stress.

  19. Cloning and Sequence Analysis of a Glucose-6-Phosphate Dehydrogenase Gene PsG6PDH from Freezing-tolerant Populus suaveolens

    Institute of Scientific and Technical Information of China (English)

    Lin Yuan-zhen; Lin Shan-zhi; Zhang Wei; Zhang Qian; Zhang Zhi-yi; Guo Huan

    2005-01-01

    A 1207 hp cDNA fragment (PsG6PDH) was amplified by PT-PCR from cold-induced total Pna of the freexing-tolerant P. Suaveolens, using primers based on the highly comserved region of published plant glucose-6-phosphate dehydrogenase (G6PDH)genes. The sepuence analysis showed that PsG6PDH coding region had 1 101 bp and encoded 367 predicted aminoacid residues. Moreover, the nucleotide sequence of psG6PDH showed 83%,82%,79%,79% and 78% identity, and the derived amino acid sequence shared 44.2%,44.7%,42.0%,40.5% and 43.9% identity with those of the Solanum tuberosum, Nicotiana tabacum, Triticum aestivum, Oryxa sativa and Arabidopsis thaliana, respectively. The results show that PsG6PDH is a new member of G6PDH gene family and belongs to cytosolic G6PDH gene. This is the first report on clonign of the G6PDH gene from woody plants.

  20. Improvement of Arabidopsis Biomass and Cold, Drought and Salinity Stress Tolerance by Modified Circadian Clock-Associated PSEUDO-RESPONSE REGULATORs.

    Science.gov (United States)

    Nakamichi, Norihito; Takao, Saori; Kudo, Toru; Kiba, Takatoshi; Wang, Yin; Kinoshita, Toshinori; Sakakibara, Hitoshi

    2016-05-01

    Plant circadian clocks control the timing of a variety of genetic, metabolic and physiological processes. Recent studies revealed a possible molecular mechanism for circadian clock regulation. Arabidopsis thaliana (Arabidopsis) PSEUDO-RESPONSE REGULATOR (PRR) genes, including TIMING OF CAB EXPRESSION 1 (TOC1), encode clock-associated transcriptional repressors that act redundantly. Disruption of multiple PRR genes results in drastic phenotypes, including increased biomass and abiotic stress tolerance, whereas PRR single mutants show subtle phenotypic differences due to genetic redundancy. In this study, we demonstrate that constitutive expression of engineered PRR5 (PRR5-VP), which functions as a transcriptional activator, can increase biomass and abiotic stress tolerance, similar to prr multiple mutants. Concomitant analyses of relative growth rate, flowering time and photosynthetic activity suggested that increased biomass of PRR5-VP plants is mostly due to late flowering, rather than to alterations in photosynthetic activity or growth rate. In addition, genome-wide gene expression profiling revealed that genes related to cold stress and water deprivation responses were up-regulated in PRR5-VP plants. PRR5-VP plants were more resistant to cold, drought and salinity stress than the wild type, whereas ft tsf and gi, well-known late flowering and increased biomass mutants, were not. These findings suggest that attenuation of PRR function by a single transformation of PRR-VP is a valuable method for increasing biomass as well as abiotic stress tolerance in Arabidopsis. Because the PRR gene family is conserved in vascular plants, PRR-VP may regulate biomass and stress responses in many plants, but especially in long-day annual plants.

  1. Dynamic regulation of genome-wide pre-mRNA splicing and stress tolerance by the Sm-like protein LSm5 in Arabidopsis

    KAUST Repository

    Cui, Peng

    2014-01-07

    Background: Sm-like proteins are highly conserved proteins that form the core of the U6 ribonucleoprotein and function in several mRNA metabolism processes, including pre-mRNA splicing. Despite their wide occurrence in all eukaryotes, little is known about the roles of Sm-like proteins in the regulation of splicing.Results: Here, through comprehensive transcriptome analyses, we demonstrate that depletion of the Arabidopsis supersensitive to abscisic acid and drought 1 gene (SAD1), which encodes Sm-like protein 5 (LSm5), promotes an inaccurate selection of splice sites that leads to a genome-wide increase in alternative splicing. In contrast, overexpression of SAD1 strengthens the precision of splice-site recognition and globally inhibits alternative splicing. Further, SAD1 modulates the splicing of stress-responsive genes, particularly under salt-stress conditions. Finally, we find that overexpression of SAD1 in Arabidopsis improves salt tolerance in transgenic plants, which correlates with an increase in splicing accuracy and efficiency for stress-responsive genes.Conclusions: We conclude that SAD1 dynamically controls splicing efficiency and splice-site recognition in Arabidopsis, and propose that this may contribute to SAD1-mediated stress tolerance through the metabolism of transcripts expressed from stress-responsive genes. Our study not only provides novel insights into the function of Sm-like proteins in splicing, but also uncovers new means to improve splicing efficiency and to enhance stress tolerance in a higher eukaryote. 2014 Cui et al.; licensee BioMed Central Ltd.

  2. The assembly of metals chelation by thiols and vacuolar compartmentalization conferred increased tolerance to and accumulation of cadmium and arsenic in transgenic Arabidopsis thaliana

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Jiangbo [Key Laboratory of Plant Resources, Institute of Botany, The Chinese Academy of Sciences, Beijing 100093 (China); Inner Mongolia Key Laboratory of Biomass-Energy Conversion, The Institute of Bioengineering and Technology, Inner Mongolia University of Science and Technology, Baotou 040100 (China); Xu, Wenzhong [Key Laboratory of Plant Resources, Institute of Botany, The Chinese Academy of Sciences, Beijing 100093 (China); Ma, Mi, E-mail: mami@ibcas.ac.cn [Key Laboratory of Plant Resources, Institute of Botany, The Chinese Academy of Sciences, Beijing 100093 (China)

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer Simultaneous transformation of AsPCS1 and ScYCF1 into Arabidopsis thaliana which is sensitive to heavy metals, leads to transgenic plants tolerant to Arsenic and cadmium. Black-Right-Pointing-Pointer Dual-gene transgenic Arabidopsis showed higher accumulation of Arsenic and cadmium than single and non-transgenic plants. Black-Right-Pointing-Pointer Our results proved that improved thiol peptides synthesis and vacuolar compartmentation in plant dramatically boosted the survival rates of plants when exposed to heavy metals. Black-Right-Pointing-Pointer A new strategy for efficient phytoremediation of heavy metals by stacking genes transformation in plants was developed in this article. - Abstract: Transgenic Arabidopsis thaliana were developed to increase tolerance for and accumulation of heavy metals and metalloids by simultaneous overexpression of AsPCS1 and YCF1 (derived from garlic and baker's yeast) based on the fact that chelation of metals and vacuolar compartmentalization are the main strategies for heavy metals/metalloids detoxification and tolerance in plants. Dual-gene transgenic lines had the longest roots and the highest accumulation of Cd and As than single-gene transgenic lines and wildtype. When grown on cadmium or arsenic (arsenite/arsenate), Dual-gene transgenic lines accumulated over 2-10 folds cadmium/arsenite and 2-3 folds arsenate than wild type or plants expressing AsPCS1 or YCF1 alone. Such stacking modified genes involved in chelation of toxic metals and vacuolar compartmentalization represents a highly promising new tool for use in phytoremediation efforts.

  3. Tolerance

    NARCIS (Netherlands)

    Doorn, van M.

    2012-01-01

    Tolerance entails acceptance of the very things one disagrees with, disapproves of or dislikes. Tolerance can be seen as ‘a flawed virtue’ (Schuyt, 2001), because it concerns acceptance of the differences between others and ourselves we would rather fight, ignore or overcome. Although tolerance carr

  4. Overexpression of a Chloroplast-located Peroxiredoxin Q Gene, SsPrxQ, Increases the Salt and Low-temperature Tolerance of Arabidopsis

    Institute of Scientific and Technical Information of China (English)

    Li-Wen Jing; Shi-Hua Chen; Xiao-Li Guo; Hui Zhang; Yan-Xiu Zhao

    2006-01-01

    Abiotic stress, such as salt, drought and extreme temperature,can result in enhanced production of reactive oxygen species (ROS). Plants have developed both enzymatic ROS-scavenging and non-enzymatic ROS-scavenging systems. The major ROS-scavenging enzymes of plants include superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT), glutathione peroxidase (GPX) and peroxiredoxins (Prxs). In the present work, we identified a gene encoding chloroplast-located peroxiredoxin Q, SsPrxQ, from Suaeda salsa L. Located at chloroplast. Overexpression of SsPrxQ in Arabidopsis leads to an increase in salt and low-temperature tolerance.

  5. A cotton (Gossypium hirsutum) DRE-binding transcription factor gene, GhDREB, confers enhanced tolerance to drought, high salt, and freezing stresses in transgenic wheat.

    Science.gov (United States)

    Gao, Shi-Qing; Chen, Ming; Xia, Lian-Qin; Xiu, Hui-Jun; Xu, Zhao-Shi; Li, Lian-Cheng; Zhao, Chang-Ping; Cheng, Xian-Guo; Ma, You-Zhi

    2009-02-01

    A cotton (G. hirsutum L.) dehydration responsive element binding protein gene, GhDREB, which encodes a 153 amino acid protein containing a conserved AP2/EREBP domain, was isolated from the cDNA library of cotton cv. Simian 3 by a yeast one-hybrid system. RNA blot analysis showed that the GhDREB gene was induced in cotton seedlings by drought, high salt and cold stresses. An electrophoretic mobility shift assay (EMSA) indicated that the GhDREB protein bound specifically to the DRE core element (A/GCCGAC) in vitro. Two expression vectors containing the GhDREB gene with either of the Ubiqutin or rd29A promoters were constructed and transferred into wheat (Triticum aestivum L.) by bombardment. Fifty-eight Ubi::GhDREB and 17 rd29A::GhDREB T(0) plants of Yangmai (36 plants) and Lumai (39 plants) were identified by PCR analysis, respectively. Southern blot and RT-PCR analyses showed that two or three copies of the GhDREB were integrated into the Yangmai 10 genome and were expressed at the transcriptional level, and three or four copies were integrated into the Lumai 23 genome. Functional analysis indicated that the transgenic plants had improved tolerance to drought, high salt, and freezing stresses through accumulating higher levels of soluble sugar and chlorophyll in leaves after stress treatments. No phenotype differences were observed between transgenic plants and their non-transgenic controls. These results indicated that GhDREB might be useful in improving wheat stress tolerance through genetic engineering.

  6. Osmolyte regulation by TonEBP/NFAT5 during anoxia-recovery and dehydration–rehydration stresses in the freeze-tolerant wood frog (Rana sylvatica

    Directory of Open Access Journals (Sweden)

    Rasha Al-attar

    2017-01-01

    Full Text Available Background The wood frog, Rana sylvatica, tolerates freezing as a means of winter survival. Freezing is considered to be an ischemic/anoxic event in which oxygen delivery is significantly impaired. In addition, cellular dehydration occurs during freezing because water is lost to extracellular compartments in order to promote freezing. In order to prevent severe cell shrinkage and cell death, it is important for the wood frog to have adaptive mechanisms for osmoregulation. One important mechanism of cellular osmoregulation occurs through the cellular uptake/production of organic osmolytes like sorbitol, betaine, and myo-inositol. Betaine and myo-inositol are transported by the proteins BGT-1 and SMIT, respectively. Sorbitol on the other hand, is synthesized inside the cell by the enzyme aldose reductase. These three proteins are regulated at the transcriptional level by the transcription factor, NFAT5/TonEBP. Therefore, the objective of this study was to elucidate the role of NFAT5/TonEBP in regulating BGT-1, SMIT, and aldose reductase, during dehydration and anoxia in the wood frog muscle, liver, and kidney tissues. Methods Wood frogs were subjected to 24 h anoxia-4 h recovery and 40% dehydration-full rehydration experiments. Protein levels of NFAT5, BGT-1, SMIT, and aldose reductase were studied using immunoblotting in muscle, liver, and kidney tissues. Results Immunoblotting results demonstrated downregulations in NFAT5 protein levels in both liver and kidney tissues during anoxia (decreases by 41% and 44% relative to control for liver and kidney, respectively. Aldose reductase protein levels also decreased in both muscle and kidney tissues during anoxia (by 37% and 30% for muscle and kidney, respectively. On the other hand, BGT-1 levels increased during anoxia in muscle (0.9-fold compared to control and kidney (1.1-fold. Under 40% dehydration, NFAT5 levels decreased in liver by 53%. Aldose reductase levels also decreased by 42% in

  7. Osmolyte regulation by TonEBP/NFAT5 during anoxia-recovery and dehydration–rehydration stresses in the freeze-tolerant wood frog (Rana sylvatica)

    Science.gov (United States)

    Al-attar, Rasha; Zhang, Yichi

    2017-01-01

    Background The wood frog, Rana sylvatica, tolerates freezing as a means of winter survival. Freezing is considered to be an ischemic/anoxic event in which oxygen delivery is significantly impaired. In addition, cellular dehydration occurs during freezing because water is lost to extracellular compartments in order to promote freezing. In order to prevent severe cell shrinkage and cell death, it is important for the wood frog to have adaptive mechanisms for osmoregulation. One important mechanism of cellular osmoregulation occurs through the cellular uptake/production of organic osmolytes like sorbitol, betaine, and myo-inositol. Betaine and myo-inositol are transported by the proteins BGT-1 and SMIT, respectively. Sorbitol on the other hand, is synthesized inside the cell by the enzyme aldose reductase. These three proteins are regulated at the transcriptional level by the transcription factor, NFAT5/TonEBP. Therefore, the objective of this study was to elucidate the role of NFAT5/TonEBP in regulating BGT-1, SMIT, and aldose reductase, during dehydration and anoxia in the wood frog muscle, liver, and kidney tissues. Methods Wood frogs were subjected to 24 h anoxia-4 h recovery and 40% dehydration-full rehydration experiments. Protein levels of NFAT5, BGT-1, SMIT, and aldose reductase were studied using immunoblotting in muscle, liver, and kidney tissues. Results Immunoblotting results demonstrated downregulations in NFAT5 protein levels in both liver and kidney tissues during anoxia (decreases by 41% and 44% relative to control for liver and kidney, respectively). Aldose reductase protein levels also decreased in both muscle and kidney tissues during anoxia (by 37% and 30% for muscle and kidney, respectively). On the other hand, BGT-1 levels increased during anoxia in muscle (0.9-fold compared to control) and kidney (1.1-fold). Under 40% dehydration, NFAT5 levels decreased in liver by 53%. Aldose reductase levels also decreased by 42% in dehydrated muscle, and by

  8. Tolerance

    DEFF Research Database (Denmark)

    Tønder, Lars

    Tolerance: A Sensorial Orientation to Politics is an experiment in re-orientation. The book is based on the wager that tolerance exceeds the more prevalent images of self-restraint and repressive benevolence because neither precludes the possibility of a more “active tolerance” motivated...... by the desire to experiment and to become otherwise. The objective is to discuss what gets lost, conceptually as well as politically, when we neglect the subsistence of active tolerance within other practices of tolerance, and to develop a theory of active tolerance in which tolerance's mobilizing character...... is linked to a different set of circumstances than the ones suggested by existing models in contemporary democratic theory. Reorienting the discussion of tolerance, the book raises the question of how to disclose new possibilities within our given context of affect and perception. Once we move away from...

  9. Expression of GhNAC2 from G. herbaceum, improves root growth and imparts tolerance to drought in transgenic cotton and Arabidopsis.

    Science.gov (United States)

    Gunapati, Samatha; Naresh, Ram; Ranjan, Sanjay; Nigam, Deepti; Hans, Aradhana; Verma, Praveen C; Gadre, Rekha; Pathre, Uday V; Sane, Aniruddha P; Sane, Vidhu A

    2016-04-26

    NAC proteins are plant-specific transcription factors that play essential roles in regulating development and responses to abiotic and biotic stresses. We show that over-expression of the cotton GhNAC2 under the CaMV35S promoter increases root growth in both Arabidopsis and cotton under unstressed conditions. Transgenic Arabidopsis plants also show improved root growth in presence of mannitol and NaCl while transgenic cotton expressing GhNAC2 show reduced leaf abscission and wilting upon water stress compared to control plants. Transgenic Arabidopsis plants also have larger leaves, higher seed number and size under well watered conditions, reduced transpiration and higher relative leaf water content. Micro-array analysis of transgenic plants over-expressing GhNAC2 reveals activation of the ABA/JA pathways and a suppression of the ethylene pathway at several levels to reduce expression of ERF6/ERF1/WRKY33/ MPK3/MKK9/ACS6 and their targets. This probably suppresses the ethylene-mediated inhibition of organ expansion, leading to larger leaves, better root growth and higher yields under unstressed conditions. Suppression of the ethylene pathway and activation of the ABA/JA pathways also primes the plant for improved stress tolerance by reduction in transpiration, greater stomatal control and suppression of growth retarding factors.

  10. STOP2 Activates Transcription of Several Genesfor AI- and Low pH-Tolerance that Are Regulatedby STOP1 in Arabidopsis

    Institute of Scientific and Technical Information of China (English)

    2014-01-01

    The zinc-finger protein STOP1 (sensitive to proton rhizotoxicity 1) regulates transcription of multiple genescritical for tolerance to aluminum (AI) and low pH in Arabidopsis. We evaluated the contributions of genes that are sup-pressed in the stop1 mutant to AI- and low pH-tolerance using T-DNA-inserted disruptants, and transgenic stop1 mutantsexpressing each of the suppressed genes. STOP2, a STOP1 homolog, partially recovered AI- and low pH-tolerance byrecovering the expression of genes regulated by STOP1. Growth and root tip viability under proton stress were partiallyrescued in the STOP2-complemented line. STOP2 localized in the nucleus and regulated transcription of two genes (PGIP1and PGIP2) associated with cell wall stabilization at low pH. GUS assays revealed that STOP1 and STOP2 showed similarcellular expression in the root. However, the expression level of STOP2 was much lower than that of STOP1. In a STOP1promoter::STOP2-complemented line, AI tolerance was slightly recovered, concomitant with the recovery of expressionof ALS3 (aluminum sensitive 3) and AtMATE (Arabidopsis thaliana multidrug and toxic compound extrusion), while theexpression of AtALMT1 (aluminum-activated malate transporter 1) was not recovered. These analyses indicated thatSTOP2 is a physiologically minor isoform of STOP1, but it can activate expression of some genes regulated by STOP1.

  11. Drought and salt stress tolerance of an Arabidopsis glutathione S-transferase U17 knockout mutant are attributed to the combined effect of glutathione and abscisic acid.

    Science.gov (United States)

    Chen, Jui-Hung; Jiang, Han-Wei; Hsieh, En-Jung; Chen, Hsing-Yu; Chien, Ching-Te; Hsieh, Hsu-Liang; Lin, Tsan-Piao

    2012-01-01

    Although glutathione S-transferases (GSTs) are thought to play major roles in oxidative stress metabolism, little is known about the regulatory functions of GSTs. We have reported that Arabidopsis (Arabidopsis thaliana) GLUTATHIONE S-TRANSFERASE U17 (AtGSTU17; At1g10370) participates in light signaling and might modulate various aspects of development by affecting glutathione (GSH) pools via a coordinated regulation with phytochrome A. Here, we provide further evidence to support a negative role of AtGSTU17 in drought and salt stress tolerance. When AtGSTU17 was mutated, plants were more tolerant to drought and salt stresses compared with wild-type plants. In addition, atgstu17 accumulated higher levels of GSH and abscisic acid (ABA) and exhibited hyposensitivity to ABA during seed germination, smaller stomatal apertures, a lower transpiration rate, better development of primary and lateral root systems, and longer vegetative growth. To explore how atgstu17 accumulated higher ABA content, we grew wild-type plants in the solution containing GSH and found that they accumulated ABA to a higher extent than plants grown in the absence of GSH, and they also exhibited the atgstu17 phenotypes. Wild-type plants treated with GSH also demonstrated more tolerance to drought and salt stresses. Furthermore, the effect of GSH on root patterning and drought tolerance was confirmed by growing the atgstu17 in solution containing l-buthionine-(S,R)-sulfoximine, a specific inhibitor of GSH biosynthesis. In conclusion, the atgstu17 phenotype can be explained by the combined effect of GSH and ABA. We propose a role of AtGSTU17 in adaptive responses to drought and salt stresses by functioning as a negative component of stress-mediated signal transduction pathways.

  12. Major latex protein-like protein 43 (MLP43) functions as a positive regulator during abscisic acid responses and confers drought tolerance in Arabidopsis thaliana.

    Science.gov (United States)

    Wang, Yanping; Yang, Li; Chen, Xi; Ye, Tiantian; Zhong, Bao; Liu, Ruijie; Wu, Yan; Chan, Zhulong

    2016-01-01

    Drought stress is one of the disadvantageous environmental conditions for plant growth and reproduction. Given the importance of abscisic acid (ABA) to plant growth and abiotic stress responses, identification of novel components involved in ABA signalling transduction is critical. In this study, we screened numerous Arabidopsis thaliana mutants by seed germination assay and identified a mutant mlp43 (major latex protein-like 43) with decreased ABA sensitivity in seed germination. The mlp43 mutant was sensitive to drought stress while the MLP43-overexpressed transgenic plants were drought tolerant. The tissue-specific expression pattern analysis showed that MLP43 was predominantly expressed in cotyledons, primary roots and apical meristems, and a subcellular localization study indicated that MLP43 was localized in the nucleus and cytoplasm. Physiological and biochemical analyses indicated that MLP43 functioned as a positive regulator in ABA- and drought-stress responses in Arabidopsis through regulating water loss efficiency, electrolyte leakage, ROS levels, and as well as ABA-responsive gene expression. Moreover, metabolite profiling analysis indicated that MLP43 could modulate the production of primary metabolites under drought stress conditions. Reconstitution of ABA signalling components in Arabidopsis protoplasts indicated that MLP43 was involved in ABA signalling transduction and acted upstream of SnRK2s by directly interacting with SnRK2.6 and ABF1 in a yeast two-hybrid assay. Moreover, ABA and drought stress down-regulated MLP43 expression as a negative feedback loop regulation to the performance of MLP43 in ABA and drought stress responses. Therefore, this study provided new insights for interpretation of physiological and molecular mechanisms of Arabidopsis MLP43 mediating ABA signalling transduction and drought stress responses.

  13. Cloning of a Vacuolar H+-pyrophosphatase Gene from the Halophyte Suaeda corniculata whose Heterologous Overexpression Improves Salt,Saline-alkali and Drought Tolerance in Arabidopsis

    Institute of Scientific and Technical Information of China (English)

    Liang Liu; Ying Wang; Nan Wana; Yuan-Yuan Dong; Xiu-Duo Fan; Xiu-Ming Liu; Jing Yang

    2011-01-01

    Salt,saline-alkali conditions,and drought are major environmental factors limiting plant growth and productivity.The vacuolar H+-translocating inorganic pyrophosphatase (V-H+-PPase) is an electrogenic proton pump that translocates protons into vacuoles in plant cells.Expression of V-H+-PPase increases in plants under a number of abiotic stresses,and is thought to have an important role in adaptation to abiotic stress.In this work,we report the isolation and characterization of the gene,ScVP,encoding a vacuolar inorganic pyrophosphatase (V-H+-PPase) from the halophyte,Suaeda corniculata.Semiquantitative reverse transcription-polymerase chain reaction analysis showed that ScVP was induced in roots,stems and leaves under treatment with salt,saline-alkali and drought.Compared with wild-type (WT) Arabidopsis,transgenic plants overexpressing ScVP accumulated more Na+ in leaves and roots,and showed increased tolerance to high salinity,saline-alkali and drought stresses.The germination percentage of transgenic Arabidopsis seeds was higher than that of WT seeds under the abiotic stresses.The root length of transgenic plants under salt stress was longer than that of WT plants.Furthermore,the rate of water loss during drought stress was higher in WT than in transgenic plants.Collectively,these results indicate that ScVP plays an important role in plant tolerance to salt,saline-alkali and drought stress.

  14. Universal Stress Protein exhibits a redox-dependent chaperone function in Arabidopsis and enhances plant tolerance to heat shock and oxidative stress

    Directory of Open Access Journals (Sweden)

    Jung eYoung Jun

    2015-12-01

    Full Text Available Although a wide range of physiological information on Universal Stress Proteins (USPs is available from many organisms, their biochemical and molecular functions remain unidentified. The biochemical function of AtUSP (At3g53990 from Arabidopsis thaliana was therefore investigated. Plants over-expressing AtUSP showed a strong resistance to heat shock and oxidative stress, compared with wild-type and Atusp knock-out plants, confirming the crucial role of AtUSP in stress tolerance. AtUSP was present in a variety of structures including monomers, dimers, trimers, and oligomeric complexes, and switched in response to external stresses from low molecular weight (LMW species to high molecular weight (HMW complexes. AtUSP exhibited a strong chaperone function under stress conditions in particular, and this activity was significantly increased by heat treatment. Chaperone activity of AtUSP was critically regulated by the redox status of cells and accompanied by structural changes to the protein. Over-expression of AtUSP conferred a strong tolerance to heat shock and oxidative stress upon Arabidopsis, primarily via its chaperone function.

  15. Transgenic Indian mustard (Brassica juncea) plants expressing an Arabidopsis phytochelatin synthase (AtPCS1) exhibit enhanced As and Cd tolerance.

    Science.gov (United States)

    Gasic, Ksenija; Korban, Schuyler S

    2007-07-01

    Phytochelatins (PCs) are post-translationally synthesized thiol reactive peptides that play important roles in detoxification of heavy metal and metalloids in plants and other living organisms. The overall goal of this study is to develop transgenic plants with increased tolerance for and accumulation of heavy metals and metalloids from soil by expressing an Arabidopsis thaliana AtPCS1 gene, encoding phytochelatin synthase (PCS), in Indian mustard (Brassica juncea L.). A FLAG-tagged AtPCS1 gDNA, under its native promoter, is expressed in Indian mustard, and transgenic pcs lines have been compared with wild-type plants for tolerance to and accumulation of cadmium (Cd) and arsenic (As). Compared to wild type plants, transgenic plants exhibit significantly higher tolerance to Cd and As. Shoots of Cd-treated pcs plants have significantly higher concentrations of PCs and thiols than those of wild-type plants. Shoots of wild-type plants accumulated significantly more Cd than those of transgenic plants, while accumulation of As in transgenic plants was similar to that in wild type plants. Although phytochelatin synthase improves the ability of Indian mustard to tolerate higher levels of the heavy metal Cd and the metalloid As, it does not increase the accumulation potential of these metals in the above ground tissues of Indian mustard plants.

  16. Drought and salt tolerance enhancement of transgenic Arabidopsis by overexpression of the vacuolar pyrophosphatase 1 (EVP1) gene from Eucalyptus globulus.

    Science.gov (United States)

    Gamboa, M C; Baltierra, F; Leon, G; Krauskopf, E

    2013-12-01

    Vacuolar solute accumulation has been shown to be a mechanism by which plants are capable of increasing drought and salt tolerance. The exposure of plants to NaCl induces H+ transport into the vacuole by specialized pumps. One of them corresponds to the vacuolar H+-pyrophosphatase, which generates a H+ gradient across the vacuolar membrane. In our laboratory we isolated the first cDNA sequence of a vacuolar pyrophosphatase type I (EVP1) from Eucalyptus globulus. Using real-time PCR we confirmed that EVP1 participates in Eucalyptus plants' response to drought and salt stress through an ABA independent pathway. Additionally, the overexpression of EVP1 in transgenic Arabidopsis resulted in an enhancement of drought and salt tolerance. Interestingly we established that the transgenic plants had a higher number of root hairs, which may have a positive effect on the plant's response to drought and salt stress. These results suggest that EVP1 plays an active role in abiotic stress tolerance in E. globulus, and that it may be potentially used to enhance drought and stress tolerance of plants.

  17. An efficient and reproducible protocol for the production of salt tolerant transgenic wheat plants expressing the Arabidopsis AtNHX1 gene.

    Science.gov (United States)

    Moghaieb, Reda E A; Sharaf, Ahmed N; Soliman, Mohamed H; El-Arabi, Nagwa I; Momtaz, Osama A

    2014-01-01

    We present an efficient method for the production of transgenic salt tolerant hexaploid wheat plants expressing the Arabidopsis AtNHX1 gene. Wheat mature zygotic embryos were isolated from two hexaploid bread wheat (Triticum aestivum) cultivars (namely: Gemmeiza 9 and Gemmeiza 10) and were transformed with the A. tumefaciens LBA4404 harboring the pBI-121 vector containing the AtNHX1 gene. Transgenic wheat lines that express the gus intron was obtained and used as control. The results confirmed that npt-II gene could be transmitted and expressed in the T2 following 3:1 Mendelian segregation while the control plant couldn't. The data indicate that, the AtNHX1 gene was integrated in a stable manner into the wheat genome and the corresponding transcripts were expressed. The transformation efficiency was 5.7 and 7.5% for cultivars Gemmeiza 10 and Gemmeiza 9, respectively. A greenhouse experiment was conducted to investigate the effect of AtNHX1 gene in wheat salt tolerance. The transgenic wheat lines could maintain high growth rate under salt stress condition (350 mM NaCl) while the control plant couldn't. The results confirmed that Na(+)/H(+) antiporter gene AtNHX1 increased salt tolerance by increasing Na(+) accumulation and keeping K+/Na(+) balance. Thus, transgenic plants showed high tolerance to salt stress and can be considered as a new genetic resource in breeding programs.

  18. The sunflower transcription factor HaHB11 confers tolerance to water deficit and salinity to transgenic Arabidopsis and alfalfa plants.

    Science.gov (United States)

    Cabello, Julieta V; Giacomelli, Jorge I; Gómez, María C; Chan, Raquel L

    2016-11-22

    Homeodomain-leucine zipper (HD-Zip) transcription factors are unique to the plant kingdom; members of subfamily I are known to be involved in abiotic stress responses. HaHB11 belongs to this subfamily and it was previously shown that it is able to confer improved yield and tolerance to flooding via a quiescent strategy. Here we show that HaHB11 expression is induced by ABA, NaCl and water deficit in sunflower seedlings and leaves. Arabidopsis transgenic plants expressing HaHB11, controlled either by its own promoter or by the constitutive 35S CaMV, presented rolled leaves and longer roots than WT when grown under standard conditions. In addition, these plants showed wider stems and more vascular bundles. To deal with drought, HaHB11 transgenic plants closed their stomata faster and lost less water than controls, triggering an enhanced tolerance to such stress condition and also to salinity stress. Concomitantly, ABA-synthesis and sensing related genes were differentially regulated in HaHB11 transgenic plants. Either under long-term salinity stress or mild drought stress, HaHB11 transgenic plants did not exhibit yield penalties. Moreover, alfalfa transgenic plants were generated which also showed enhanced drought tolerance. Altogether, the results indicated that HaHB11 was able to confer drought and salinity tolerance via a complex mechanism which involves morphological, physiological and molecular changes.

  19. CBF gene copy number variation at Frost Resistance-2 is associated with levels of freezing tolerance in temperate-climate cereals.

    Science.gov (United States)

    Knox, Andrea K; Dhillon, Taniya; Cheng, Hongmei; Tondelli, Alessandro; Pecchioni, Nicola; Stockinger, Eric J

    2010-06-01

    Frost Resistance-1 (FR-1) and FR-2 are two loci affecting freezing tolerance and winter hardiness of the temperate-climate cereals. FR-1 is hypothesized to be due to the pleiotropic effects of VRN-1. FR-2 spans a cluster of C-Repeat Binding Factor (CBF) genes. These loci are genetically and functionally linked. Recent studies indicate CBF transcripts are downregulated by the VRN-1 encoded MADS-box protein or a factor in the VRN-1 pathway. Here, we report that barley genotypes 'Dicktoo' and 'Nure' carrying a vrn-H1 winter allele at VRN-H1 harbor increased copy numbers of CBF coding sequences relative to Vrn-H1 spring allele genotypes 'Morex' and 'Tremois'. Sequencing bacteriophage lambda genomic clones from these four genotypes alongside DNA blot hybridizations indicate approximately half of the eleven CBF orthologs at FR-H2 are duplicated in individual genomes. One of these duplications discriminates vrn-H1 genotypes from Vrn-H1 genotypes. The vrn-H1 winter allele genotypes harbor tandem segmental duplications through the CBF2A-CBF4B genomic region and maintain two distinct CBF2 paralogs, while the Vrn-H1 spring allele genotypes harbor single copies of CBF2 and CBF4. An additional CBF gene, CBF13, is a pseudogene interrupted by multiple non-sense codons in 'Tremois' whereas CBF13 is a complete uninterrupted coding sequence in 'Dicktoo' and 'Nure'. DNA blot hybridization with wheat DNAs reveals greater copy numbers of CBF14 also occurs in winter wheats than in spring wheats. These data indicate that variation in CBF gene copy numbers is widespread in the Triticeae and suggest selection for winter hardiness co-selects winter alleles at both VRN-1 and FR-2.

  20. Transcriptional regulation of heat shock proteins and ascorbate peroxidase by CtHsfA2b from African bermudagrass conferring heat tolerance in Arabidopsis

    Science.gov (United States)

    Wang, Xiuyun; Huang, Wanlu; Yang, Zhimin; Liu, Jun; Huang, Bingru

    2016-01-01

    Heat stress transcription factor A2s (HsfA2s) are key regulators in plant response to high temperature. Our objectives were to isolate an HsfA2 gene (CtHsfA2b) from a warm-season grass species, African bermudagrass (Cynodon transvaalensis Burtt-Davy), and to determine the physiological functions and transcriptional regulation of HsfA2 for improving heat tolerance. Gene expression analysis revealed that CtHsfA2b was heat-inducible and exhibited rapid response to increasing temperature. Ectopic expression of CtHsfA2b improved heat tolerance in Arabidopsis and restored heat-sensitive defects of Arabidopsis hsfa2 mutant, which was demonstrated by higher survival rate and photosynthetic parameters, and lower electrolyte leakage in transgenic plants compared to the WT or hsfa2 mutant. CtHsfA2b transgenic plants showed elevated transcriptional regulation of several downstream genes, including those encoding ascorbate peroxidase (AtApx2) and heat shock proteins [AtHsp18.1-CI, AtHsp22.0-ER, AtHsp25.3-P and AtHsp26.5-P(r), AtHsp70b and AtHsp101-3]. CtHsfA2b was found to bind to the heat shock element (HSE) on the promoter of AtApx2 and enhanced transcriptional activity of AtApx2. These results suggested that CtHsfA2b could play positive roles in heat protection by up-regulating antioxidant defense and chaperoning mechanisms. CtHsfA2b has the potential to be used as a candidate gene to genetically modify cool-season species for improving heat tolerance. PMID:27320381

  1. Enhanced expression of EsWAX1 improves drought tolerance with increased accumulation of cuticular wax and ascorbic acid in transgenic Arabidopsis.

    Science.gov (United States)

    Zhu, Lin; Guo, Jiansheng; Zhu, Jian; Zhou, Cheng

    2014-02-01

    Drought can activate several stress responses in plants, such as stomatal closure, accumulation of cuticular wax and ascorbic acid (AsA), which have been correlated with improvement of drought tolerance. In this study, a novel MYB gene, designed as EsWAX1, was isolated and characterized from Eutrema salsugineum. EsWAX1 contained a full-length open reading frame (ORF) of 1068 bp, which encoding 355 amino acids. Transcript levels of EsWAX1 were quickly inducible by drought stress and ABA treatment, indicating that EsWAX1 may act as a positive regulator in response to drought stress. Ectopic expression of EsWAX1 increased accumulation of cuticular wax via modulating the expression of several wax-related genes, such as CER1, KCS2 and KCR1. Scanning electron microscopy further revealed higher densities of wax crystalline structures on the adaxial surfaces of leaves in transgenic Arabidopsis plants. In addition, the expression of several AsA biosynthetic genes (VTC1, GLDH and MIOX4) was significantly up-regulated in EsWAX1-overexpressing lines and these transgenic plants have approximately 23-27% more total AsA content than WT plants. However, the high-level expression of EsWAX1 severely disrupted plant normal growth and development. To reduce negative effects of EsWAX1 over-expression on plant growth, we generated transgenic Arabidopsis plants expressing EsWAX1 driven by the stress-inducible RD29A promoter. Our data indicated the RD29A::EsWAX1 transgenic plants had greater tolerance to drought stress than wild-type plants. Taken together, the EsWAX1 gene is a potential regulator that may be utilized to improve plant drought tolerance by genetic manipulation.

  2. Chilling- and Freezing-Induced Alterations in Cytosine Methylation and Its Association with the Cold Tolerance of an Alpine Subnival Plant, Chorispora bungeana.

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    Yuan Song

    Full Text Available Chilling (0-18°C and freezing (<0°C are two distinct types of cold stresses. Epigenetic regulation can play an important role in plant adaptation to abiotic stresses. However, it is not yet clear whether and how epigenetic modification (i.e., DNA methylation mediates the adaptation to cold stresses in nature (e.g., in alpine regions. Especially, whether the adaptation to chilling and freezing is involved in differential epigenetic regulations in plants is largely unknown. Chorispora bungeana is an alpine subnival plant that is distributed in the freeze-thaw tundra in Asia, where chilling and freezing frequently fluctuate daily (24 h. To disentangle how C. bungeana copes with these intricate cold stresses through epigenetic modifications, plants of C. bungeana were treated at 4°C (chilling and -4°C (freezing over five periods of time (0-24 h. Methylation-sensitive amplified fragment-length polymorphism markers were used to investigate the variation in DNA methylation of C. bungeana in response to chilling and freezing. It was found that the alterations in DNA methylation of C. bungeana largely occurred over the period of chilling and freezing. Moreover, chilling and freezing appeared to gradually induce distinct DNA methylation variations, as the treatment went on (e.g., after 12 h. Forty-three cold-induced polymorphic fragments were randomly selected and further analyzed, and three of the cloned fragments were homologous to genes encoding alcohol dehydrogenase, UDP-glucosyltransferase and polygalacturonase-inhibiting protein. These candidate genes verified the existence of different expressive patterns between chilling and freezing. Our results showed that C. bungeana responded to cold stresses rapidly through the alterations of DNA methylation, and that chilling and freezing induced different DNA methylation changes. Therefore, we conclude that epigenetic modifications can potentially serve as a rapid and flexible mechanism for C. bungeana

  3. Transgenic Arabidopsis thaliana plants expressing a β-1,3-glucanase from sweet sorghum (Sorghum bicolor L.) show reduced callose deposition and increased tolerance to aluminium toxicity.

    Science.gov (United States)

    Zhang, Hui; Shi, Wu Liang; You, Jiang Feng; Bian, Ming Di; Qin, Xiao Mei; Yu, Hui; Liu, Qing; Ryan, Peter R; Yang, Zhen Ming

    2015-06-01

    Seventy-one cultivars of sweet sorghum (Sorghum bicolor L.) were screened for aluminium (Al) tolerance by measuring relative root growth (RRG). Two contrasting cultivars, ROMA (Al tolerant) and POTCHETSTRM (Al sensitive), were selected to study shorter term responses to Al stress. POTCHETSTRM had higher callose synthase activity, lower β-1,3-glucanase activity and more callose deposition in the root apices during Al treatment compared with ROMA. We monitored the expression of 12 genes involved in callose synthesis and degradation and found that one of these, SbGlu1 (Sb03g045630.1), which encodes a β-1,3-glucanase enzyme, best explained the contrasting deposition of callose in ROMA and POTCHETSTRM during Al treatment. Full-length cDNAs of SbGlu1 was prepared from ROMA and POTCHETSTRM and expressed in Arabidopsis thaliana using the constitutive cauliflower mosaic virus (CaMV) 35S promoter. Independent transgenic lines displayed significantly greater Al tolerance than wild-type plants and vector-only controls. This phenotype was associated with greater total β-1,3-glucanase activity, less Al accumulation and reduced callose deposition in the roots. These results suggest that callose production is not just an early indicator of Al stress in plants but likely to be part of the toxicity pathway that leads to the inhibition of root growth.

  4. The Arabidopsis gibberellin methyl transferase 1 suppresses gibberellin activity, reduces whole-plant transpiration and promotes drought tolerance in transgenic tomato.

    Science.gov (United States)

    Nir, Ido; Moshelion, Menachem; Weiss, David

    2014-01-01

    Previous studies have shown that reduced gibberellin (GA) level or signal promotes plant tolerance to environmental stresses, including drought, but the underlying mechanism is not yet clear. Here we studied the effects of reduced levels of active GAs on tomato (Solanum lycopersicum) plant tolerance to drought as well as the mechanism responsible for these effects. To reduce the levels of active GAs, we generated transgenic tomato overexpressing the Arabidopsis thaliana GA METHYL TRANSFERASE 1 (AtGAMT1) gene. AtGAMT1 encodes an enzyme that catalyses the methylation of active GAs to generate inactive GA methyl esters. Tomato plants overexpressing AtGAMT1 exhibited typical GA-deficiency phenotypes and increased tolerance to drought stress. GA application to the transgenic plants restored normal growth and sensitivity to drought. The transgenic plants maintained high leaf water status under drought conditions, because of reduced whole-plant transpiration. The reduced transpiration can be attributed to reduced stomatal conductance. GAMT1 overexpression inhibited the expansion of leaf-epidermal cells, leading to the formation of smaller stomata with reduced stomatal pores. It is possible that under drought conditions, plants with reduced GA activity and therefore, reduced transpiration, will suffer less from leaf desiccation, thereby maintaining higher capabilities and recovery rates.

  5. Overexpression of pigeonpea stress-induced cold and drought regulatory gene (CcCDR) confers drought, salt, and cold tolerance in Arabidopsis.

    Science.gov (United States)

    Tamirisa, Srinath; Vudem, Dashavantha Reddy; Khareedu, Venkateswara Rao

    2014-09-01

    A potent cold and drought regulatory protein-encoding gene (CcCDR) was isolated from the subtractive cDNA library of pigeonpea plants subjected to drought stress. CcCDR was induced by different abiotic stress conditions in pigeonpea. Overexpression of CcCDR in Arabidopsis thaliana imparted enhanced tolerance against major abiotic stresses, namely drought, salinity, and low temperature, as evidenced by increased biomass, root length, and chlorophyll content. Transgenic plants also showed increased levels of antioxidant enzymes, proline, and reducing sugars under stress conditions. Furthermore, CcCDR-transgenic plants showed enhanced relative water content, osmotic potential, and cell membrane stability, as well as hypersensitivity to abscisic acid (ABA) as compared with control plants. Localization studies confirmed that CcCDR could enter the nucleus, as revealed by intense fluorescence, indicating its possible interaction with various nuclear proteins. Microarray analysis revealed that 1780 genes were up-regulated in CcCDR-transgenics compared with wild-type plants. Real-time PCR analysis on selected stress-responsive genes, involved in ABA-dependent and -independent signalling networks, revealed higher expression levels in transgenic plants, suggesting that CcCDR acts upstream of these genes. The overall results demonstrate the explicit role of CcCDR in conferring multiple abiotic stress tolerance at the whole-plant level. The multifunctional CcCDR seems promising as a prime candidate gene for enhancing abiotic stress tolerance in diverse plants.

  6. Improvement of copper tolerance of Arabidopsis by transgenic expression of an allene oxide cyclase gene, GhAOC1, in upland cotton (Gossypium hirsutum L.)

    Institute of Scientific and Technical Information of China (English)

    Yuange Wang; Huaihua Liu; Qingguo Xin

    2015-01-01

    Allene oxide cyclase (AOC, E 5.3.99.6) is an essential enzyme in the jasmonic acid (JA) biosynthetic pathway and mediates a wide range of adaptive responses. In this report, five AOC genes (GhAOC1–GhAOC5) were cloned from upland cotton (Gossypium hirsutum L.), sequenced, and characterized. Real-time PCR analysis indicated that the transcripts of GhAOCs were abundantly expressed in roots and less in fibers, and regulated in cotton plants under methyl jasmonate (MeJA) and CuCl2 stresses. To investigate the role of GhAOC under copper stress, transgenic Arabidopsis plants overexpressing cotton GhAOC1 under control of the Cauliflower mosaic virus 35S (CaMV 35S) promoter were generated. Compared to untransformed plants, GhAOC1-overexpressing Arabidopsis thaliana plants exhibited markedly higher survival rate, shoot fresh weight, shoot dry weight, and photosynthetic efficiency, and reduced cell membrane damage and lipid peroxidation under copper stress. This study provides the first evidence that GhAOC1 plays an important role in copper stress tolerance.

  7. Improvement of copper tolerance of Arabidopsis by transgenic expression of an allene oxide cyclase gene, GhAOC1, in upland cotton (Gossypium hirsutum L.

    Directory of Open Access Journals (Sweden)

    Yuange Wang

    2015-08-01

    Full Text Available Allene oxide cyclase (AOC, E 5.3.99.6 is an essential enzyme in the jasmonic acid (JA biosynthetic pathway and mediates a wide range of adaptive responses. In this report, five AOC genes (GhAOC1–GhAOC5 were cloned from upland cotton (Gossypium hirsutum L., sequenced, and characterized. Real-time PCR analysis indicated that the transcripts of GhAOCs were abundantly expressed in roots and less in fibers, and regulated in cotton plants under methyl jasmonate (MeJA and CuCl2 stresses. To investigate the role of GhAOC under copper stress, transgenic Arabidopsis plants overexpressing cotton GhAOC1 under control of the Cauliflower mosaic virus 35S (CaMV 35S promoter were generated. Compared to untransformed plants, GhAOC1-overexpressing Arabidopsis thaliana plants exhibited markedly higher survival rate, shoot fresh weight, shoot dry weight, and photosynthetic efficiency, and reduced cell membrane damage and lipid peroxidation under copper stress. This study provides the first evidence that GhAOC1 plays an important role in copper stress tolerance.

  8. Comprehensive Analysis of Rice Laccase Gene (OsLAC) Family and Ectopic Expression of OsLAC10 Enhances Tolerance to Copper Stress in Arabidopsis

    Science.gov (United States)

    Liu, Qingquan; Luo, Le; Wang, Xiaoxiao; Shen, Zhenguo; Zheng, Luqing

    2017-01-01

    Laccases are encoded by a multigene family and widely distributed in plant genomes where they play roles oxidizing monolignols to produce higher-order lignin involved in plant development and stress responses. We identified 30 laccase genes (OsLACs) from rice, which can be divided into five subfamilies, mostly expressed during early development of the endosperm, growing roots, and stems. OsLACs can be induced by hormones, salt, drought, and heavy metals stresses. The expression level of OsLAC10 increased 1200-fold after treatment with 20 μM Cu for 12 h. The laccase activities of OsLAC10 were confirmed in an Escherichia coli expression system. Lignin accumulation increased in the roots of Arabidopsis over-expressing OsLAC10 (OsLAC10-OX) compared to wild-type controls. After growth on 1/2 Murashige and Skoog (MS) medium containing toxic levels of Cu for seven days, roots of the OsLAC10-OX lines were significantly longer than those of the wild type. Compared to control plants, the Cu concentration decreased significantly in roots of the OsLAC10-OX line under hydroponic conditions. These results provided insights into the evolutionary expansion and functional divergence of OsLAC family. In addition, OsLAC10 is likely involved in lignin biosynthesis, and reduces the uptake of Cu into roots required for Arabidopsis to develop tolerance to Cu. PMID:28146098

  9. Improvement of copper tolerance of Arabidopsis by transgenic expression of an allene oxide cyclase gene,GhA OC1, in upland cotton(Gossypium hirsutum L.)

    Institute of Scientific and Technical Information of China (English)

    Yuange; Wang; Huaihua; Liu; Qingguo; Xin

    2015-01-01

    Allene oxide cyclase(AOC, E 5.3.99.6) is an essential enzyme in the jasmonic acid(JA)biosynthetic pathway and mediates a wide range of adaptive responses. In this report, five AOC genes(Gh AOC1–Gh AOC5) were cloned from upland cotton(Gossypium hirsutum L.),sequenced, and characterized. Real-time PCR analysis indicated that the transcripts of Gh AOCs were abundantly expressed in roots and less in fibers, and regulated in cotton plants under methyl jasmonate(Me JA) and Cu Cl2 stresses. To investigate the role of Gh AOC under copper stress, transgenic Arabidopsis plants overexpressing cotton Gh AOC1 under control of the Cauliflower mosaic virus 35S(Ca MV 35S) promoter were generated. Compared to untransformed plants, Gh AOC1-overexpressing Arabidopsis thaliana plants exhibited markedly higher survival rate, shoot fresh weight, shoot dry weight, and photosynthetic efficiency, and reduced cell membrane damage and lipid peroxidation under copper stress.This study provides the first evidence that Gh AOC1 plays an important role in copper stress tolerance.

  10. Improvement of drought and salt tolerance in Arabidopsis and Lotus corniculatus by overexpression of a novel DREB transcription factor from Populus euphratica.

    Science.gov (United States)

    Zhou, Mei-Liang; Ma, Jiang-Tao; Zhao, Yang-Min; Wei, Ya-Hui; Tang, Yi-Xiong; Wu, Yan-Min

    2012-09-10

    A novel DREB (dehydration-responsive element binding) gene, designated PeDREB2a, was isolated from the desert-grown tree, Populus euphratica Oliv. PeDREB2a is classified into the A-5 group of DREB subfamily based on multiple sequence alignment and phylogenetic characterization. Using semi-quantitative RT-PCR, we found that the PeDREB2a was greatly induced by drought, NaCl, low temperature, 1-naphthaleneacetic acid (NAA), 6-benzyl aminopurine (6-BA) and gibberellic acid (GA3) treatments in P. euphratica seedling. Yeast transactivity assay demonstrated that PeDREB2a gene encodes a transcription activator. Overexpression of PeDREB2a under the stress-inducible rd29A promotor in transgenic Arabidopsis and Lotus corniculatus forage plants resulted in enhanced tolerance to salt and drought stresses. The PeDREB2a overexpressing Arabidopsis lines showed higher root length and plant height and had elevated levels of soluble sugars and lower levels of malondialdehyde under stress conditions compared to control plants. The results revealed that PeDREB2a play an essential role as a DREB transcription factor in regulation of stress-responsive signaling in P. euphratica.

  11. A maize calcium-dependent protein kinase gene, ZmCPK4, positively regulated abscisic acid signaling and enhanced drought stress tolerance in transgenic Arabidopsis.

    Science.gov (United States)

    Jiang, Shanshan; Zhang, Dan; Wang, Li; Pan, Jiaowen; Liu, Yang; Kong, Xiangpei; Zhou, Yan; Li, Dequan

    2013-10-01

    Calcium-dependent protein kinases (CDPKs) play essential roles in calcium-mediated signal transductions in plant response to abiotic stress. Several members have been identified to be regulators for plants response to abscisic acid (ABA) signaling. Here, we isolated a subgroup I CDPK gene, ZmCPK4, from maize. Quantitative real time PCR (qRT-PCR) analysis revealed that the ZmCPK4 transcripts were induced by various stresses and signal molecules. Transient and stable expression of the ZmCPK4-GFP fusion proteins revealed ZmCPK4 localized to the membrane. Moreover, overexpression of ZmCPK4 in the transgenic Arabidopsis enhanced ABA sensitivity in seed germination, seedling growth and stomatal movement. The transgenic plants also enhanced drought stress tolerance. Taken together, the results suggest that ZmCPK4 might be involved in ABA-mediated regulation of stomatal closure in response to drought stress.

  12. HsfA1d, a Protein Identified via FOX Hunting Using Thellungiella salsuginea cDNAs Improves Heat Tolerance by Regulating Heat-Stress-Responsive Gene Expression

    Institute of Scientific and Technical Information of China (English)

    Yukari Higashi; Naohiko Ohama; Tomoko Ishikawa; Taku Katori; Ayaka Shimura; Kazuya Kusakabe; Kazuko Yamaguchi-Shinozaki

    2013-01-01

    Theilungiella salsuginea (formerly T.halophila),a species closely related to Arabidopsis (Arabidopsis thaliana),is tolerant not only to high salt levels,but also to chilling,freezing,and ozone.Here,we report that T.salsuginea also shows greater heat tolerance than Arabidopsis.We identified T.salsuginea HsfAld (TsHsfAld) as a gene that can confer marked heat tolerance on Arabidopsis.TsHsfAld was identified via Full-length cDNA Over-eXpressing gene (FOX) hunting from among a collection of heat-stress-related T.salsuginea cDNAs.Transgenic Arabidopsis overexpressing TsHsfAld showed constitutive up-regulation of many genes in the Arabidopsis AtHsfA1 regulon under normal growth temperature.In Arabidopsis mesophyll protoplasts,TsHsfAld was localized in both the nucleus and the cytoplasm.TsHsfAld also interacted with AtHSP90,which negatively regulates AtHsfAls by forming HsfA1-HSP90 complexes in the cytoplasm.It is likely that the partial nuclear localization of TsHsfAld induced the expression of the AtHsfAld regulon in the transgenic plants at normal temperature.We also discovered that transgenic Arabidopsis plants overexpressing AtHsfAld were more heat-tolerant than wild-type plants and up-regulated the expression of the HsfAld regulon,as was observed in TsHsfAld-overexpressing plants.We propose that the products of both TsHsfAld and AtHsfAld function as positive regulators of Arabidopsis heat-stress response and would be useful for the improvement of heat-stress tolerance in other plants.

  13. Overexpression of VrUBC1, a Mung Bean E2 Ubiquitin-Conjugating Enzyme, Enhances Osmotic Stress Tolerance in Arabidopsis.

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    Eunsook Chung

    Full Text Available The ubiquitin conjugating enzyme E2 (UBC E2 mediates selective ubiquitination, acting with E1 and E3 enzymes to designate specific proteins for subsequent degradation. In the present study, we characterized the function of the mung bean VrUBC1 gene (Vigna radiata UBC 1. RNA gel-blot analysis showed that VrUBC1 mRNA expression was induced by either dehydration, high salinity or by the exogenous abscisic acid (ABA, but not by low temperature or wounding. Biochemical studies of VrUBC1 recombinant protein and complementation of yeast ubc4/5 by VrUBC1 revealed that VrUBC1 encodes a functional UBC E2. To understand the function of this gene in development and plant responses to osmotic stresses, we overexpressed VrUBC1 in Arabidopsis (Arabidopsis thaliana. The VrUBC1-overexpressing plants displayed highly sensitive responses to ABA and osmotic stress during germination, enhanced ABA- or salt-induced stomatal closing, and increased drought stress tolerance. The expression levels of a number of key ABA signaling genes were increased in VrUBC1-overexpressing plants compared to the wild-type plants. Yeast two-hybrid and bimolecular fluorescence complementation demonstrated that VrUBC1 interacts with AtVBP1 (A. thalianaVrUBC1 Binding Partner 1, a C3HC4-type RING E3 ligase. Overall, these results demonstrate that VrUBC1 plays a positive role in osmotic stress tolerance through transcriptional regulation of ABA-related genes and possibly through interaction with a novel RING E3 ligase.

  14. Rice cyclophilin OsCYP18-2 is translocated to the nucleus by an interaction with SKIP and enhances drought tolerance in rice and Arabidopsis.

    Science.gov (United States)

    Lee, Sang Sook; Park, Hyun Ji; Yoon, Dae Hwa; Kim, Beom-Gi; Ahn, Jun Cheul; Luan, Sheng; Cho, Hye Sun

    2015-10-01

    Cyclophilin 18-2 (CYP18-2) genes, homologues of human peptidyl-prolyl isomerase-like 1 (PPiL1), are conserved across multicellular organisms and Schizosaccharomyces pombe. Although PPiL1 is known to interact with ski-interacting protein (SKIP), a transcriptional co-regulator and spliceosomal component, there have been no functional analyses of PPiL1 homologues in plants. Rice cyclophilin 18-2 (OsCYP18-2) bound directly to amino acids 56-95 of OsSKIP and its binding was independent of cyclosporin A, a cyclophilin-binding drug. Moreover, OsCYP18-2 exhibited PPIase activity regardless of its interaction with OsSKIP. Therefore, the binding site for OsCYP18-2's interaction with SKIP was distinct from the PPIase active site. OsCYP18-2's interaction with SKIP full-length protein enabled OsCYP18-2's translocation from the cytoplasm into the nucleus and AtSKIP interacted in planta with both AtCYP18-2 and OsCYP18-2. Drought and salt stress induced similar expression of OsCYP18-2 and OsSKIP. Overexpression of OsCYP18-2 in transgenic rice and Arabidopsis thaliana plants enhanced drought tolerance and altered expression and pre-mRNA splicing patterns of stress-related genes in Arabidopsis under drought conditions. Furthermore, OsCYP18-2 caused transcriptional activation with/without OsSKIP in the GAL4 system of yeast; thus the OsSKIP-OsCYP18-2 interaction has an important role in the transcriptional and post-transcriptional regulation of stress-related genes and increases tolerance to drought stress.

  15. Overexpression of VrUBC1, a Mung Bean E2 Ubiquitin-Conjugating Enzyme, Enhances Osmotic Stress Tolerance in Arabidopsis.

    Science.gov (United States)

    Chung, Eunsook; Cho, Chang-Woo; So, Hyun-Ah; Kang, Jee-Sook; Chung, Young Soo; Lee, Jai-Heon

    2013-01-01

    The ubiquitin conjugating enzyme E2 (UBC E2) mediates selective ubiquitination, acting with E1 and E3 enzymes to designate specific proteins for subsequent degradation. In the present study, we characterized the function of the mung bean VrUBC1 gene (Vigna radiata UBC 1). RNA gel-blot analysis showed that VrUBC1 mRNA expression was induced by either dehydration, high salinity or by the exogenous abscisic acid (ABA), but not by low temperature or wounding. Biochemical studies of VrUBC1 recombinant protein and complementation of yeast ubc4/5 by VrUBC1 revealed that VrUBC1 encodes a functional UBC E2. To understand the function of this gene in development and plant responses to osmotic stresses, we overexpressed VrUBC1 in Arabidopsis (Arabidopsis thaliana). The VrUBC1-overexpressing plants displayed highly sensitive responses to ABA and osmotic stress during germination, enhanced ABA- or salt-induced stomatal closing, and increased drought stress tolerance. The expression levels of a number of key ABA signaling genes were increased in VrUBC1-overexpressing plants compared to the wild-type plants. Yeast two-hybrid and bimolecular fluorescence complementation demonstrated that VrUBC1 interacts with AtVBP1 (A. thalianaVrUBC1 Binding Partner 1), a C3HC4-type RING E3 ligase. Overall, these results demonstrate that VrUBC1 plays a positive role in osmotic stress tolerance through transcriptional regulation of ABA-related genes and possibly through interaction with a novel RING E3 ligase.

  16. Arabidopsis Raf-Like Mitogen-Activated Protein Kinase Kinase Kinase Gene Raf43 Is Required for Tolerance to Multiple Abiotic Stresses.

    Directory of Open Access Journals (Sweden)

    Nasar Virk

    Full Text Available Mitogen-activated protein kinase (MAPK cascades are critical signaling modules that mediate the transduction of extracellular stimuli into intracellular response. A relatively large number of MAPKKKs have been identified in a variety of plant genomes but only a few of them have been studied for their biological function. In the present study, we identified an Arabidopsis Raf-like MAPKKK gene Raf43 and studied its function in biotic and abiotic stress response using a T-DNA insertion mutant raf43-1 and two Raf43-overexpressing lines Raf43-OE#1 and Raf43-OE#13. Expression of Raf43 was induced by multiple abiotic and biotic stresses including treatments with drought, mannitol and oxidative stress or defense signaling molecule salicylic acid and infection with necrotrophic fungal pathogen Botrytis cinerea. Seed germination and seedling root growth of raf43-1 were significantly inhibited on MS medium containing mannitol, NaCl, H2O2 or methyl viologen (MV while seed germination and seedling root growth of the Raf43-OE#1 and Raf43-OE#13 lines was similar to wild type Col-0 under the above stress conditions. Soil-grown raf43-1 plants exhibited reduced tolerance to MV, drought and salt stress. Abscisic acid inhibited significantly seed germination and seedling root growth of the raf43-1 line but had no effect on the two Raf43-overexpressing lines. Expression of stress-responsive RD17 and DREB2A genes was significantly down-regulated in raf43-1 plants. However, the raf43-1 and Raf43-overexpressing plants showed similar disease phenotype to the wild type plants after infection with B. cinerea or Pseudomonas syringae pv. tomato DC3000. Our results demonstrate that Raf43, encoding for a Raf-like MAPKKK, is required for tolerance to multiple abiotic stresses in Arabidopsis.

  17. The root-colonizing endophyte Pirifomospora indica confers drought tolerance in Arabidopsis by stimulating the expression of drought stress-related genes in leaves.

    Science.gov (United States)

    Sherameti, Irena; Tripathi, Swati; Varma, Ajit; Oelmüller, Ralf

    2008-06-01

    Piriformospora indica is an endophytic fungus that colonizes the roots of many plant species, including Arabidopsis. We exposed 18-day-old Arabidopsis seedlings, which were either cocultivated with the fungus or mock-treated for the last 9 days, to mild drought stress for 84 h. During the first 36 to 48 h, seedlings cocultivated with the fungus continued to grow, while the uncolonized controls did not. This results in a threefold difference in the fresh weight and a more than twofold difference in the chlorophyll content. The photosynthetic efficiency was only slightly reduced in the colonized (F variable/F maximum [Fv/Fm] at t(0 h) = 0.82 and t(36 h) = 0.79) and was severely impaired in the uncolonized (Fv/Fm at t(0 h) = 0.81 and (t)(36 h) = 0.49) seedlings, which also showed symptoms of withering. When seedlings exposed to drought stress for 72 or 84 h were transferred to soil, 10% (72 h) and none (84 h) of uncolonized seedlings reached the flowering stage and produced seeds, while 59% (72 h) and 47% (84 h) of the colonized seedlings flowered and produced seeds. After exposure to drought stress for 3 h, the message levels for RESPONSE TO DEHYDRATION 29A, EARLY RESPONSE TO DEHYDRATION1, ANAC072, DEHYDRATION-RESPONSE ELEMENT BINDING PROTEIN2A, SALT-, AND DROUGHT-INDUCED RING FINGER1, phospholipase Ddelta, CALCINEURIN B-LIKE PROTEIN (CBL)1, CBL-INTERACTING PROTEIN KINASE3, and the histone acetyltransferase (HAT) were upregulated in the leaves of P. indica-colonized seedlings. Uncolonized seedlings responded 3 to 6 h later, and the message levels increased much less. We identified an Arabidopsis ethylmethane-sulfonate mutant that is less resistant to drought stress and in which the stress-related genes were not upregulated in the presence of P. indica. Thus, P. indica confers drought-stress tolerance to Arabidopsis, and this is associated with the priming of the expression of a quite diverse set of stress-related genes in the leaves. Transfer to soil was again

  18. Overexpression of a Soybean Ariadne-Like Ubiquitin Ligase Gene GmARI1 Enhances Aluminum Tolerance in Arabidopsis

    OpenAIRE

    Xiaolian Zhang; Ning Wang; Pei Chen; Mengmeng Gao; Juge Liu; Yufeng Wang; Tuanjie Zhao; Yan Li; Junyi Gai

    2014-01-01

    Ariadne (ARI) subfamily of RBR (Ring Between Ring fingers) proteins have been found as a group of putative E3 ubiquitin ligases containing RING (Really Interesting New Gene) finger domains in fruitfly, mouse, human and Arabidopsis. Recent studies showed several RING-type E3 ubiquitin ligases play important roles in plant response to abiotic stresses, but the function of ARI in plants is largely unknown. In this study, an ariadne-like E3 ubiquitin ligase gene was isolated from soybean, Glycine...

  19. A Cyclin Dependent Kinase Regulatory Subunit (CKS) Gene of Pigeonpea Imparts Abiotic Stress Tolerance and Regulates Plant Growth and Development in Arabidopsis.

    Science.gov (United States)

    Tamirisa, Srinath; Vudem, Dashavantha R; Khareedu, Venkateswara R

    2017-01-01

    Frequent climatic changes in conjunction with other extreme environmental factors are known to affect growth, development and productivity of diverse crop plants. Pigeonpea, a major grain legume of the semiarid tropics, endowed with an excellent deep-root system, is known as one of the important drought tolerant crop plants. Cyclin dependent kinases (CDKs) are core cell cycle regulators and play important role in different aspects of plant growth and development. The cyclin-dependent kinase regulatory subunit gene (CKS) was isolated from the cDNA library of pigeonpea plants subjected to drought stress. Pigeonpea CKS (CcCKS) gene expression was detected in both the root and leaf tissues of pigeonpea and was upregulated by polyethylene glycol (PEG), mannitol, NaCl and abscisic acid (ABA) treatments. The overexpression of CcCKS gene in Arabidopsis significantly enhanced tolerance of transgenics to drought and salt stresses as evidenced by different physiological parameters. Under stress conditions, transgenics showed higher biomass, decreased rate of water loss, decreased MDA levels, higher free proline contents, and glutathione levels. Moreover, under stress conditions transgenics exhibited lower stomatal conductance, lower transpiration, and higher photosynthetic rates. However, under normal conditions, CcCKS-transgenics displayed decreased plant growth rate, increased cell size and decreased stomatal number compared to those of wild-type plants. Real-time polymerase chain reaction revealed that CcCKS could regulate the expression of both ABA-dependent and ABA-independent genes associated with abiotic stress tolerance as well as plant growth and development. As such, the CcCKS seems promising and might serve as a potential candidate gene for enhancing the abiotic stress tolerance of crop plants.

  20. Molecular cloning and characterization of a novel freezing-inducible DREB1/CBF transcription factor gene in boreal plant Iceland poppy (Papaver nudicaule

    Directory of Open Access Journals (Sweden)

    Zhuo Huang

    Full Text Available Abstract DREB1 of the AP2/ERF superfamily plays a key role in the regulation of plant response to low temperatures. In this study, a novel DREB1/CBF transcription factor, PnDREB1, was isolated from Iceland poppy (Papaver nudicaule, a plant adaptive to low temperature environments. It is homologous to the known DREB1s of Arabidopsis and other plant species. It also shares similar 3D structure, and conserved and functionally important motifs with DREB1s of Arabidopsis. The phylogenetic analysis indicated that the AP2 domain of PnDREB1 is similar to those of Glycine max, Medicago truncatula, and M. sativa. PnDREB1 is constitutively expressed in diverse tissues and is increased in roots. qPCR analyses indicated that PnDREB1 is significantly induced by freezing treatment as well as by abscissic acid. The expression levels induced by freezing treatment were higher in the variety with higher degree of freezing tolerance. These results suggested that PnDREB1 is a novel and functional DREB1 transcription factor involved in freezing response and possibly in other abiotic stresses. Furthermore, the freezing-induction could be suppressed by exogenous gibberellins acid, indicating that PnDREB1 might play some role in the GA signaling transduction pathway. This study provides a basis for better understanding the roles of DREB1 in adaption of Iceland poppy to low temperatures.

  1. Differential patterns of reactive oxygen species and antioxidative mechanisms during atrazine injury and sucrose-induced tolerance in Arabidopsis thaliana plantlets

    Directory of Open Access Journals (Sweden)

    Couée Ivan

    2009-03-01

    Full Text Available Abstract Background Besides being essential for plant structure and metabolism, soluble carbohydrates play important roles in stress responses. Sucrose has been shown to confer to Arabidopsis seedlings a high level of tolerance to the herbicide atrazine, which causes reactive oxygen species (ROS production and oxidative stress. The effects of atrazine and of exogenous sucrose on ROS patterns and ROS-scavenging systems were studied. Simultaneous analysis of ROS contents, expression of ROS-related genes and activities of ROS-scavenging enzymes gave an integrative view of physiological state and detoxifying potential under conditions of sensitivity or tolerance. Results Toxicity of atrazine could be related to inefficient activation of singlet oxygen (1O2 quenching pathways leading to 1O2 accumulation. Atrazine treatment also increased hydrogen peroxide (H2O2 content, while reducing gene expressions and enzymatic activities related to two major H2O2-detoxification pathways. Conversely, sucrose-protected plantlets in the presence of atrazine exhibited efficient 1O2 quenching, low 1O2 accumulation and active H2O2-detoxifying systems. Conclusion In conclusion, sucrose protection was in part due to activation of specific ROS scavenging systems with consequent reduction of oxidative damages. Importance of ROS combination and potential interferences of sucrose, xenobiotic and ROS signalling pathways are discussed.

  2. Overexpression of soybean ubiquitin-conjugating enzyme gene GmUBC2 confers enhanced drought and salt tolerance through modulating abiotic stress-responsive gene expression in Arabidopsis.

    Science.gov (United States)

    Zhou, Guo-An; Chang, Ru-Zhen; Qiu, Li-Juan

    2010-03-01

    Previous studies have shown that ubiquitination plays important roles in plant abiotic stress responses. In the present study, the ubiquitin-conjugating enzyme gene GmUBC2, a homologue of yeast RAD6, was cloned from soybean and functionally characterized. GmUBC2 was expressed in all tissues in soybean and was up-regulated by drought and salt stress. Arabidopsis plants overexpressing GmUBC2 were more tolerant to salinity and drought stresses compared with the control plants. Through expression analyses of putative downstream genes in the transgenic plants, we found that the expression levels of two ion antiporter genes AtNHX1 and AtCLCa, a key gene involved in the biosynthesis of proline, AtP5CS, and the copper chaperone for superoxide dismutase gene AtCCS, were all increased significantly in the transgenic plants. These results suggest that GmUBC2 is involved in the regulation of ion homeostasis, osmolyte synthesis, and oxidative stress responses. Our results also suggest that modulation of the ubiquitination pathway could be an effective means of improving salt and drought tolerance in plants through genetic engineering.

  3. AtPP2CG1, a protein phosphatase 2C, positively regulates salt tolerance of Arabidopsis in abscisic acid-dependent manner

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xin, E-mail: fangfei6073@126.com [Plant Bioengineering Laboratory, Northeast Agricultural University, Harbin 150030 (China); Zhu, Yanming, E-mail: ymzhu2001@neau.edu.cn [Plant Bioengineering Laboratory, Northeast Agricultural University, Harbin 150030 (China); Zhai, Hong, E-mail: Zhai.h@neigaehrb.ac.cn [Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Harbin 150040 (China); Cai, Hua, E-mail: small-big@sohu.com [Plant Bioengineering Laboratory, Northeast Agricultural University, Harbin 150030 (China); Ji, Wei, E-mail: iwei_j@hotmail.com [Plant Bioengineering Laboratory, Northeast Agricultural University, Harbin 150030 (China); Luo, Xiao, E-mail: luoxiao2010@yahoo.cn [Plant Bioengineering Laboratory, Northeast Agricultural University, Harbin 150030 (China); Li, Jing, E-mail: lijing@neau.edu.cn [Plant Secondary Metabolism Laboratory, Northeast Agricultural University, Harbin 150030 (China); Bai, Xi, E-mail: baixi@neau.edu.cn [Plant Bioengineering Laboratory, Northeast Agricultural University, Harbin 150030 (China)

    2012-06-15

    Highlights: Black-Right-Pointing-Pointer AtPP2CG1 positively regulates salt tolerance in ABA-dependent manner. Black-Right-Pointing-Pointer AtPP2CG1 up-regulates the expression of marker genes in different pathways. Black-Right-Pointing-Pointer AtPP2CG1 expresses in the vascular system and trichomes of Arabidopsis. -- Abstract: AtPP2CG1 (Arabidopsis thaliana protein phosphatase 2C G Group 1) was predicted as an abiotic stress candidate gene by bioinformatic analysis in our previous study. The gene encodes a putative protein phosphatase 2C that belongs to Group G of PP2C. There is no report of Group G genes involved in abiotic stress so far. Real-time RT-PCR analysis showed that AtPP2CG1 expression was induced by salt, drought, and abscisic acid (ABA) treatment. The expression levels of AtPP2CG1 in the ABA synthesis-deficient mutant abi2-3 were much lower than that in WT plants under salt stress suggesting that the expression of AtPP2CG1 acts in an ABA-dependent manner. Over-expression of AtPP2CG1 led to enhanced salt tolerance, whereas its loss of function caused decreased salt tolerance. These results indicate that AtPP2CG1 positively regulates salt stress in an ABA-dependent manner. Under salt treatment, AtPP2CG1 up-regulated the expression levels of stress-responsive genes, including RD29A, RD29B, DREB2A and KIN1. GUS activity was detected in roots, leaves, stems, flower, and trichomes of AtPP2CG1 promoter-GUS transgenic plants. AtPP2CG1 protein was localized in nucleus and cytoplasm via AtPP2CG1:eGFP and YFP:AtPP2CG1 fusion approaches.

  4. Overexpression of Grain Amaranth (Amaranthus hypochondriacus) AhERF or AhDOF Transcription Factors in Arabidopsis thaliana Increases Water Deficit- and Salt-Stress Tolerance, Respectively, via Contrasting Stress-Amelioration Mechanisms

    Science.gov (United States)

    Massange-Sánchez, Julio A.; Palmeros-Suárez, Paola A.; Espitia-Rangel, Eduardo; Rodríguez-Arévalo, Isaac; Sánchez-Segura, Lino; Martínez-Gallardo, Norma A.; Alatorre-Cobos, Fulgencio; Tiessen, Axel; Délano-Frier, John P.

    2016-01-01

    Two grain amaranth transcription factor (TF) genes were overexpressed in Arabidopsis plants. The first, coding for a group VII ethylene response factor TF (i.e., AhERF-VII) conferred tolerance to water-deficit stress (WS) in transgenic Arabidopsis without affecting vegetative or reproductive growth. A significantly lower water-loss rate in detached leaves coupled to a reduced stomatal opening in leaves of plants subjected to WS was associated with this trait. WS tolerance was also associated with an increased antioxidant enzyme activity and the accumulation of putative stress-related secondary metabolites. However, microarray and GO data did not indicate an obvious correlation between WS tolerance, stomatal closure, and abscisic acid (ABA)-related signaling. This scenario suggested that stomatal closure during WS in these plants involved ABA-independent mechanisms, possibly involving reactive oxygen species (ROS). WS tolerance may have also involved other protective processes, such as those employed for methyl glyoxal detoxification. The second, coding for a class A and cluster I DNA binding with one finger TF (i.e., AhDof-AI) provided salt-stress (SS) tolerance with no evident fitness penalties. The lack of an obvious development-related phenotype contrasted with microarray and GO data showing an enrichment of categories and genes related to developmental processes, particularly flowering. SS tolerance also correlated with increased superoxide dismutase activity but not with augmented stomatal closure. Additionally, microarray and GO data indicated that, contrary to AhERF-VII, SS tolerance conferred by AhDof-AI in Arabidopsis involved ABA-dependent and ABA-independent stress amelioration mechanisms. PMID:27749893

  5. Glutathione plays an essential role in nitric oxide-mediated iron-deficiency signaling and iron-deficiency tolerance in Arabidopsis.

    Science.gov (United States)

    Shanmugam, Varanavasiappan; Wang, Yi-Wen; Tsednee, Munkhtsetseg; Karunakaran, Krithika; Yeh, Kuo-Chen

    2015-11-01

    Iron (Fe) deficiency is a common agricultural problem that affects both the productivity and nutritional quality of plants. Thus, identifying the key factors involved in the tolerance of Fe deficiency is important. In the present study, the zir1 mutant, which is glutathione deficient, was found to be more sensitive to Fe deficiency than the wild type, and grew poorly in alkaline soil. Other glutathione-deficient mutants also showed various degrees of sensitivity to Fe-limited conditions. Interestingly, we found that the glutathione level was increased under Fe deficiency in the wild type. By contrast, blocking glutathione biosynthesis led to increased physiological sensitivity to Fe deficiency. On the other hand, overexpressing glutathione enhanced the tolerance to Fe deficiency. Under Fe-limited conditions, glutathione-deficient mutants, zir1, pad2 and cad2 accumulated lower levels of Fe than the wild type. The key genes involved in Fe uptake, including IRT1, FRO2 and FIT, are expressed at low levels in zir1; however, a split-root experiment suggested that the systemic signals that govern the expression of Fe uptake-related genes are still active in zir1. Furthermore, we found that zir1 had a lower accumulation of nitric oxide (NO) and NO reservoir S-nitrosoglutathione (GSNO). Although NO is a signaling molecule involved in the induction of Fe uptake-related genes during Fe deficiency, the NO-mediated induction of Fe-uptake genes is dependent on glutathione supply in the zir1 mutant. These results provide direct evidence that glutathione plays an essential role in Fe-deficiency tolerance and NO-mediated Fe-deficiency signaling in Arabidopsis.

  6. Arabidopsis thaliana Contains Both Ni2+ and Zn2+ Dependent Glyoxalase I Enzymes and Ectopic Expression of the Latter Contributes More towards Abiotic Stress Tolerance in E. coli

    Science.gov (United States)

    Jain, Muskan; Batth, Rituraj; Kumari, Sumita; Mustafiz, Ananda

    2016-01-01

    The glyoxalase pathway is ubiquitously found in all the organisms ranging from prokaryotes to eukaryotes. It acts as a major pathway for detoxification of methylglyoxal (MG), which deleteriously affects the biological system in stress conditions. The first important enzyme of this system is Glyoxalase I (GLYI). It is a metalloenzyme which requires divalent metal ions for its activity. This divalent metal ion can be either Zn2+ as found in most of eukaryotes or Ni2+ as seen in prokaryotes. In the present study, we have found three active GLYI enzymes (AtGLYI2, AtGLYI3 and AtGLYI6) belonging to different metal activation classes coexisting in Arabidopsis thaliana. These enzymes have been found to efficiently complement the GLYI yeast mutants. These three enzymes have been characterized in terms of their activity, metal dependency, kinetic parameters and their role in conferring tolerance to multiple abiotic stresses in E. coli and yeast. AtGLYI2 was found to be Zn2+ dependent whereas AtGLYI3 and AtGLYI6 were Ni2+ dependent. Enzyme activity of Zn2+ dependent enzyme, AtGLYI2, was observed to be exceptionally high (~250–670 fold) as compared to Ni2+ dependent enzymes, AtGLYI3 and AtGLYI6. The activity of these GLYI enzymes correlated well to their role in stress tolerance. Heterologous expression of these enzymes in E. coli led to better tolerance against various stress conditions. This is the first report of a higher eukaryotic species having multiple active GLYI enzymes belonging to different metal activation classes. PMID:27415831

  7. Arabidopsis thaliana Contains Both Ni2+ and Zn2+ Dependent Glyoxalase I Enzymes and Ectopic Expression of the Latter Contributes More towards Abiotic Stress Tolerance in E. coli.

    Directory of Open Access Journals (Sweden)

    Muskan Jain

    Full Text Available The glyoxalase pathway is ubiquitously found in all the organisms ranging from prokaryotes to eukaryotes. It acts as a major pathway for detoxification of methylglyoxal (MG, which deleteriously affects the biological system in stress conditions. The first important enzyme of this system is Glyoxalase I (GLYI. It is a metalloenzyme which requires divalent metal ions for its activity. This divalent metal ion can be either Zn2+ as found in most of eukaryotes or Ni2+ as seen in prokaryotes. In the present study, we have found three active GLYI enzymes (AtGLYI2, AtGLYI3 and AtGLYI6 belonging to different metal activation classes coexisting in Arabidopsis thaliana. These enzymes have been found to efficiently complement the GLYI yeast mutants. These three enzymes have been characterized in terms of their activity, metal dependency, kinetic parameters and their role in conferring tolerance to multiple abiotic stresses in E. coli and yeast. AtGLYI2 was found to be Zn2+ dependent whereas AtGLYI3 and AtGLYI6 were Ni2+ dependent. Enzyme activity of Zn2+ dependent enzyme, AtGLYI2, was observed to be exceptionally high (~250-670 fold as compared to Ni2+ dependent enzymes, AtGLYI3 and AtGLYI6. The activity of these GLYI enzymes correlated well to their role in stress tolerance. Heterologous expression of these enzymes in E. coli led to better tolerance against various stress conditions. This is the first report of a higher eukaryotic species having multiple active GLYI enzymes belonging to different metal activation classes.

  8. Ectopic expression of UGT75D1, a glycosyltransferase preferring indole-3-butyric acid, modulates cotyledon development and stress tolerance in seed germination of Arabidopsis thaliana.

    Science.gov (United States)

    Zhang, Gui-Zhi; Jin, Shang-Hui; Jiang, Xiao-Yi; Dong, Rui-Rui; Li, Pan; Li, Yan-Jie; Hou, Bing-Kai

    2016-01-01

    The formation of auxin glucose conjugate is proposed to be one of the molecular modifications controlling auxin homeostasis. However, the involved mechanisms and relevant physiological significances are largely unknown or poorly understood. In this study, Arabidopsis UGT75D1 was at the first time identified to be an indole-3-butyric acid (IBA) preferring glycosyltransferase. Assessment of enzyme activity and IBA conjugates in transgenic plants ectopically expressing UGT75D1 indicated that the UGT75D1 catalytic specificity was maintained in planta. It was found that the expression pattern of UGT75D1 was specific in germinating seeds. Consistently, we found that transgenic seedlings with over-produced UGT75D1 exhibited smaller cotyledons and cotyledon epidermal cells than the wild type. In addition, UGT75D1 was found to be up-regulated under mannitol, salt and ABA treatments and the over-expression lines were tolerant to osmotic and salt stresses during germination, resulting in an increased germination rate. Quantitative RT-PCR analysis revealed that the mRNA levels of ABA INSENSITIVE 3 (ABI3) and ABI5 gene in ABA signaling were substantially down-regulated in the transgenic lines under stress treatments. Interestingly, AUXIN RESPONSE FACTOR 16 (ARF16) gene of transgenic lines was also dramatically down-regulated under the same stress conditions. Since ARF16 functions as an activator of ABI3 transcription, we supposed that UGT75D1 might play a role in stress tolerance during germination through modulating ARF16-ABI3 signaling. Taken together, our work indicated that, serving as the IBA preferring glycosyltransferase but distinct from other auxin glycosyltransferases identified so far, UGT75D1 might be a very important player mediating a crosstalk between cotyledon development and stress tolerance of germination at the early stage of plant growth.

  9. Role of Arabidopsis RAP2.4 in Regulating Light-and Ethylene-Mediated Developmental Processes and Drought Stress Tolerance

    Institute of Scientific and Technical Information of China (English)

    Rong-Cheng Lin; Hee-Jin Park; Hai-Yang Wang

    2008-01-01

    Light and the plant hormone ethylene regulate many aspects of plant growth and development in an overlapping and interdependent fashion. Little is known regarding how their signal transduction pathways cross-talk to regulate plant development in a coordinated manner. Here, we report functional characterization of an AP2/DREB-type transcription factor, Arabidopsis RAP2.4, in mediating light and ethylene signaling. Expression of the RAP2.4 gene is down-regulated by light but up-regulated by salt and drought stresses. RAP2.4 protein is constitutively targeted to the nucleus and it can bind to both the ethylene-responsive GCC-box and the dehydration-responsive element (DRE).We show that RAP2.4 protein possesses an intrinsic transcriptional activation activity in yeast cells and that it can activate a reporter gene driven by the DRE cis-element in Arabidopsis protoplasts. Overexpression of RAP2.4 or mutation in RAP2.4 cause altered expression of representative light-, ethylene-, and drought-responsive genes. Although no salient phenotype was observed with a rap2.4 loss-of-function mutant, constitutive overexpression of RAP2.4 results in defects in multiple developmental processes regulated by light and ethylene, including hypocotyl elongation and gravitropism, apical hook formation and cotyledon expansion, flowering time, root elongation, root hair formation, and drought tolerance.Based on these observations, we propose that RAP2.4 acts at or downstream of a converging point of light and ethylene signaling pathways to coordinately regulate multiple developmental processes and stress responses.

  10. Auxin and its transport play a role in plant tolerance to arsenite-induced oxidative stress in Arabidopsis thaliana.

    Science.gov (United States)

    Krishnamurthy, Aparna; Rathinasabapathi, Bala

    2013-10-01

    The role of auxin in plant development is well known; however, its possible function in root response to abiotic stress is poorly understood. In this study, we demonstrate a novel role of auxin transport in plant tolerance to oxidative stress caused by arsenite. Plant response to arsenite [As(III)] was evaluated by measuring root growth and markers for stress on seedlings treated with control or As(III)-containing medium. Auxin transporter mutants aux1, pin1 and pin2 were significantly more sensitive to As(III) than the wild type (WT). Auxin transport inhibitors significantly reduced plant tolerance to As(III) in the WT, while exogenous supply of indole-3-acetic acid improved As(III) tolerance of aux1 and not that of WT. Uptake assays using H(3) -IAA showed As(III) affected auxin transport in WT roots. As(III) increased the levels of H2 O2 in WT but not in aux1, suggesting a positive role for auxin transport through AUX1 on plant tolerance to As(III) stress via reactive oxygen species (ROS)-mediated signalling. Compared to the WT, the mutant aux1 was significantly more sensitive to high-temperature stress and salinity, also suggesting auxin transport influences a common element shared by plant tolerance to arsenite, salinity and high-temperature stress.

  11. Ethylene response factor BnERF2-like (ERF2.4) from Brassica napus L. enhances submergence tolerance and alleviates oxidative damage caused by submergence in Arabidopsis thaliana

    Institute of Scientific and Technical Information of China (English)

    Yanyan Lv; Sanxiong Fu; Song Chen; Wei Zhang; Cunkou Qi

    2016-01-01

    Ethylene response factor proteins play an important role in regulating a variety of stress responses in plants, but their exact functions in submergence stress are not well understood. In this study, we isolated BnERF2.4 from Brassica napus L. to study its function in submergence tolerance. The expression of the BnERF2.4 gene in B. napus and the expression of antioxidant enzyme genes in transgenic Arabidopsis were analyzed by quantitative RT-PCR. The expression of BnERF2.4 was induced by submergence in B. napus and the overexpression of BnERF2.4 in Arabidopsis increased the level of tolerance to submergence and oxidative stress. A histochemical method detected lower levels of H2O2, O2•− and malondialdehyde (MDA) in transgenic Arabidopsis. Compared to the wild type, transgenic lines also had higher soluble sugar content and higher activity of antioxidant enzymes, which helped to protect plants against the oxidative damage caused by submergence. It was concluded that BnERF2.4 increased the tolerance of plants to submergence stress and may be involved in regulating soluble sugar content and the antioxidant system in defense against submergence stress.

  12. Overexpression of small heat shock protein LimHSP16.45 in Arabidopsis enhances tolerance to abiotic stresses.

    Directory of Open Access Journals (Sweden)

    Changjun Mu

    Full Text Available Small heat shock proteins (smHSPs play important and extensive roles in plant defenses against abiotic stresses. We cloned a gene for a smHSP from the David Lily (Lilium davidii (E. H. Wilson Raffill var. Willmottiae, which we named LimHSP16.45 based on its protein molecular weight. Its expression was induced by many kinds of abiotic stresses in both the lily and transgenic plants of Arabidopsis. Heterologous expression enhanced cell viability of the latter under high temperatures, high salt, and oxidative stress, and heat shock granules (HSGs formed under heat or salinity treatment. Assays of enzymes showed that LimHSP16.45 overexpression was related to greater activity by superoxide dismutase and catalase in transgenic lines. Therefore, we conclude that heterologous expression can protect plants against abiotic stresses by preventing irreversible protein aggregation, and by scavenging cellular reactive oxygen species.

  13. ESKIMO1 is a key gene involved in water economy as well as cold acclimation and salt tolerance

    DEFF Research Database (Denmark)

    Bouchabke-Coussa, O.; Quashie, M.L.; Seoane, Jose Miguel;

    2008-01-01

    Background: Drought is a major social and economic problem resulting in huge yield reduction in the field. Today's challenge is to develop plants with reduced water requirements and stable yields in fluctuating environmental conditions. Arabidopsis thaliana is an excellent model for identifying p...... to elucidate the function of the ESKIMO1 protein and the way it modulates plant water uptake.......Background: Drought is a major social and economic problem resulting in huge yield reduction in the field. Today's challenge is to develop plants with reduced water requirements and stable yields in fluctuating environmental conditions. Arabidopsis thaliana is an excellent model for identifying...... as a key gene involved in plant water economy as well as cold acclimation and salt tolerance. Results: All esk1 mutants were more tolerant to freezing, after acclimation, than their wild type counterpart. esk1 mutants also showed increased tolerance to mild water deficit for all traits measured. The mutant...

  14. Characteristics of sugar surfactants in stabilizing proteins during freeze-thawing and freeze-drying.

    Science.gov (United States)

    Imamura, Koreyoshi; Murai, Katsuyuki; Korehisa, Tamayo; Shimizu, Noriyuki; Yamahira, Ryo; Matsuura, Tsutashi; Tada, Hiroko; Imanaka, Hiroyuki; Ishida, Naoyuki; Nakanishi, Kazuhiro

    2014-06-01

    Sugar surfactants with different alkyl chain lengths and sugar head groups were compared for their protein-stabilizing effect during freeze-thawing and freeze-drying. Six enzymes, different in terms of tolerance against inactivation because of freeze-thawing and freeze-drying, were used as model proteins. The enzyme activities that remained after freeze-thawing and freeze-drying in the presence of a sugar surfactant were measured for different types and concentrations of sugar surfactants. Sugar surfactants stabilized all of the tested enzymes both during freeze-thawing and freeze-drying, and a one or two order higher amount of added sugar surfactant was required for achieving protein stabilization during freeze-drying than for the cryoprotection. The comprehensive comparison showed that the C10-C12 esters of sucrose or trehalose were the most effective through the freeze-drying process: the remaining enzyme activities after freeze-thawing and freeze-drying increased at the sugar ester concentrations of 1-10 and 10-100 μM, respectively, and increased to a greater extent than for the other surfactants at higher concentrations. Results also indicate that, when a decent amount of sugar was also added, the protein-stabilizing effect of a small amount of sugar ester through the freeze-drying process could be enhanced.

  15. Overexpression of the Mg-chelatase H subunit in guard cells confers drought tolerance via promotion of stomatal closure in Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Tomo eTsuzuki

    2013-10-01

    Full Text Available The Mg-chelatase H subunit (CHLH has been shown to mediate chlorophyll biosynthesis, as well as plastid-to-nucleus and abscisic acid (ABA-mediated signaling. A recent study using a novel CHLH mutant, rtl1, indicated that CHLH specifically affects ABA-induced stomatal closure, but also that CHLH did not serve as an ABA receptor in Arabidopsis thaliana. However, the molecular mechanism by which CHLH engages in ABA-mediated signaling in guard cells remains largely unknown. In the present study, we examined CHLH function in guard cells and explored whether CHLH expression might influence stomatal aperture. Incubation of rtl1 guard cell protoplasts with ABA induced expression of the ABA-responsive genes RAB18 and RD29B, as also observed in wild-type (WT cells, indicating that CHLH did not affect the expression of ABA-responsive genes. Earlier, ABA was reported to inhibit blue light (BL-mediated stomatal opening, at least in part through dephosphorylating/inhibiting guard cell H+-ATPase (which drives opening. Therefore, we immunohistochemically examined the phosphorylation status of guard cell H+-ATPase. Notably, ABA inhibition of BL-induced phosphorylation of H+-ATPase was impaired in rtl1 cells, suggesting that CHLH influences not only ABA-induced stomatal closure but also inhibition of BL-mediated stomatal opening by ABA. Next, we generated CHLH-GFP-overexpressing plants using CER6 promoter, which induces gene expression in the epidermis including guard cells. CHLH-transgenic plants exhibited a closed stomata phenotype even when brightly illuminated. Moreover, plant growth experiments conducted under water-deficient conditions showed that CHLH transgenic plants were more tolerant of drought than WT plants. In summary, we show that CHLH is involved in the regulation of stomatal aperture in response to ABA, but not in ABA-induced gene expression, and that manipulation of stomatal aperture via overexpression of CHLH in guard cells improves plant

  16. Cloning and Functional Characterization of a Vacuolar Na+/H+ Antiporter Gene from Mungbean (VrNHX1) and Its Ectopic Expression Enhanced Salt Tolerance in Arabidopsis thaliana

    Science.gov (United States)

    Mishra, Sagarika; Alavilli, Hemasundar; Lee, Byeong-ha; Panda, Sanjib Kumar; Sahoo, Lingaraj

    2014-01-01

    Plant vacuolar NHX exchangers play a significant role in adaption to salt stress by compartmentalizing excess cytosolic Na+ into vacuoles and maintaining cellular homeostasis and ionic equilibrium. We cloned an orthologue of the vacuolar Na+/H+ antiporter gene, VrNHX1 from mungbean (Vigna radiata), an important Asiatic grain legume. The VrNHX1 (Genbank Accession number JN656211.1) contains 2095 nucleotides with an open reading frame of 1629 nucleotides encoding a predicted protein of 542 amino acids with a deduced molecular mass of 59.6 kDa. The consensus amiloride binding motif (84LFFIYLLPPI93) was observed in the third putative transmembrane domain of VrNHX1. Bioinformatic and phylogenetic analysis clearly suggested that VrNHX1 had high similarity to those of orthologs belonging to Class-I clade of plant NHX exchangers in leguminous crops. VrNHX1 could be strongly induced by salt stress in mungbean as the expression in roots significantly increased in presence of 200 mM NaCl with concomitant accumulation of total [Na+]. Induction of VrNHX1 was also observed under cold and dehydration stress, indicating a possible cross talk between various abiotic stresses. Heterologous expression in salt sensitive yeast mutant AXT3 complemented for the loss of yeast vacuolar NHX1 under NaCl, KCl and LiCl stress indicating that VrNHX1 was the orthologue of ScNHX1. Further, AXT3 cells expressing VrNHX1 survived under low pH environment and displayed vacuolar alkalinization analyzed using pH sensitive fluorescent dye BCECF-AM. The constitutive and stress inducible expression of VrNHX1 resulted in enhanced salt tolerance in transgenic Arabidopsis thaliana lines. Our work suggested that VrNHX1 was a salt tolerance determinant in mungbean. PMID:25350285

  17. Cloning and functional characterization of a vacuolar Na+/H+ antiporter gene from mungbean (VrNHX1 and its ectopic expression enhanced salt tolerance in Arabidopsis thaliana.

    Directory of Open Access Journals (Sweden)

    Sagarika Mishra

    Full Text Available Plant vacuolar NHX exchangers play a significant role in adaption to salt stress by compartmentalizing excess cytosolic Na+ into vacuoles and maintaining cellular homeostasis and ionic equilibrium. We cloned an orthologue of the vacuolar Na+/H+ antiporter gene, VrNHX1 from mungbean (Vigna radiata, an important Asiatic grain legume. The VrNHX1 (Genbank Accession number JN656211.1 contains 2095 nucleotides with an open reading frame of 1629 nucleotides encoding a predicted protein of 542 amino acids with a deduced molecular mass of 59.6 kDa. The consensus amiloride binding motif (84LFFIYLLPPI93 was observed in the third putative transmembrane domain of VrNHX1. Bioinformatic and phylogenetic analysis clearly suggested that VrNHX1 had high similarity to those of orthologs belonging to Class-I clade of plant NHX exchangers in leguminous crops. VrNHX1 could be strongly induced by salt stress in mungbean as the expression in roots significantly increased in presence of 200 mM NaCl with concomitant accumulation of total [Na+]. Induction of VrNHX1 was also observed under cold and dehydration stress, indicating a possible cross talk between various abiotic stresses. Heterologous expression in salt sensitive yeast mutant AXT3 complemented for the loss of yeast vacuolar NHX1 under NaCl, KCl and LiCl stress indicating that VrNHX1 was the orthologue of ScNHX1. Further, AXT3 cells expressing VrNHX1 survived under low pH environment and displayed vacuolar alkalinization analyzed using pH sensitive fluorescent dye BCECF-AM. The constitutive and stress inducible expression of VrNHX1 resulted in enhanced salt tolerance in transgenic Arabidopsis thaliana lines. Our work suggested that VrNHX1 was a salt tolerance determinant in mungbean.

  18. Overexpression of Rice Glutaredoxin OsGrx_C7 and OsGrx_C2.1 Reduces Intracellular Arsenic Accumulation and Increases Tolerance in Arabidopsis thaliana

    Science.gov (United States)

    Verma, Pankaj K.; Verma, Shikha; Pande, Veena; Mallick, Shekhar; Deo Tripathi, Rudra; Dhankher, Om P.; Chakrabarty, Debasis

    2016-01-01

    Glutaredoxins (Grxs) are a family of small multifunctional proteins involved in various cellular functions, including redox regulation and protection under oxidative stress. Despite the high number of Grx genes in plant genomes (48 Grxs in rice), the biological functions and physiological roles of most of them remain unknown. Here, the functional characterization of the two arsenic-responsive rice Grx family proteins, OsGrx_C7 and OsGrx_C2.1 are reported. Over-expression of OsGrx_C7 and OsGrx_C2.1 in transgenic Arabidopsis thaliana conferred arsenic (As) tolerance as reflected by germination, root growth assay, and whole plant growth. Also, the transgenic expression of OsGrxs displayed significantly reduced As accumulation in A. thaliana seeds and shoot tissues compared to WT plants during both AsIII and AsV stress. Thus, OsGrx_C7 and OsGrx_C2.1 seem to be an important determinant of As-stress response in plants. OsGrx_C7 and OsGrx_C2.1 transgenic showed to maintain intracellular GSH pool and involved in lowering AsIII accumulation either by extrusion or reducing uptake by altering the transcript of A. thaliana AtNIPs. Overall, OsGrx_C7 and OsGrx_C2.1 may represent a Grx family protein involved in As stress response and may allow a better understanding of the As induced stress pathways and the design of strategies for the improvement of stress tolerance as well as decreased As content in crops. PMID:27313586

  19. Overexpression of Nictaba-Like Lectin Genes from Glycine max Confers Tolerance towards Pseudomonas syringae Infection, Aphid Infestation and Salt Stress in Transgenic Arabidopsis Plants

    Directory of Open Access Journals (Sweden)

    Sofie Van Holle

    2016-10-01

    Full Text Available Plants have evolved a sophisticated immune system that allows them to recognize invading pathogens by specialized receptors. Carbohydrate-binding proteins or lectins are part of this immune system and especially the lectins that reside in the nucleocytoplasmic compartment are known to be implicated in biotic and abiotic stress responses. The class of Nictaba-like lectins (NLL groups all proteins with homology to the tobacco (Nicotiana tabacum lectin, known as a stress-inducible lectin. Here we focus on two Nictaba homologs from soybean (Glycine max, referred to as GmNLL1 and GmNLL2. Confocal laser scanning microscopy of fusion constructs with the green fluorescent protein either transiently expressed in Nicotiana benthamiana leaves or stably transformed in tobacco BY-2 suspension cells revealed a nucleocytoplasmic localization for the GmNLLs under study. RT-qPCR analysis of the transcript levels for the Nictaba-like lectins in soybean demonstrated that the genes are expressed in several tissues throughout the development of the plant. Furthermore, it was shown that salt treatment, Phytophthora sojae infection and Aphis glycines infestation trigger the expression of particular NLL genes. Stress experiments with Arabidopsis lines overexpressing the NLLs from soybean yielded an enhanced tolerance of the plant towards bacterial infection (Pseudomonas syringae, insect infestation (Myzus persicae and salinity. Our data showed a better performance of the transgenic lines compared to wild type plants, indicating that the NLLs from soybean are implicated in the stress response. These data can help to further elucidate the physiological importance of the Nictaba-like lectins from soybean, which can ultimately lead to the design of crop plants with a better tolerance to changing environmental conditions.

  20. A Glycine soja 14-3-3 protein GsGF14o participates in stomatal and root hair development and drought tolerance in Arabidopsis thaliana.

    Science.gov (United States)

    Sun, Xiaoli; Luo, Xiao; Sun, Mingzhe; Chen, Chao; Ding, Xiaodong; Wang, Xuedong; Yang, Shanshan; Yu, Qingyue; Jia, Bowei; Ji, Wei; Cai, Hua; Zhu, Yanming

    2014-01-01

    It is well established that 14-3-3 proteins are key regulators of multiple stress signal transduction cascades. However, the biological functions of soybean 14-3-3 proteins, especially in plant drought response, are not yet known. In this study, we characterized a Glycine soja 14-3-3 gene, GsGF14o, which is involved in plant development and drought response. GsGF14o expression was greatly induced by drought stress, as evidenced by the quantitative real-time PCR and β-glucuronidase (GUS) activity analysis. GsGF14o overexpression in Arabidopsis thaliana resulted in decreased drought tolerance during seed germination and seedling growth. Furthermore, silencing of AtGF14µ, the most homologous 14-3-3 gene of GsGF14o, led to enhanced drought tolerance at both the seed germination and seedling stage. Unexpectedly, GsGF14o transgenic lines showed reduced water loss and transpiration rates compared with wild-type plants, which was demonstrated to be the consequence of the decreased stomatal size. At the same time, the smaller stomata due to GsGF14o overexpression led to a relatively slow net photosynthesis rate, which led to a growth penalty under drought stress. We further demonstrated that GsGF14o overexpression caused deficits in root hair formation and development, and thereby reduced the water intake capacity of the transgenic root system. In addition, GsGF14o overexpression down-regulated the transcript levels of drought-responsive marker genes. Finally, we also investigated the tissue-specific accumulation of GsGF14o by using a GUS activity assay. Collectively, the results presented here confirm that GsGF14o plays a dual role in drought stress responses through its involvement in the regulation of stomatal size and root hair development.

  1. Cadmium-inducible expression of the ABC-type transporter AtABCC3 increases phytochelatin-mediated cadmium tolerance in Arabidopsis.

    Science.gov (United States)

    Brunetti, Patrizia; Zanella, Letizia; De Paolis, Angelo; Di Litta, Davide; Cecchetti, Valentina; Falasca, Giuseppina; Barbieri, Maurizio; Altamura, Maria Maddalena; Costantino, Paolo; Cardarelli, Maura

    2015-07-01

    The heavy metal cadmium (Cd) is a widespread environmental contaminant with harmful effects on living cells. In plants, phytochelatin (PC)-dependent Cd detoxification requires that PC-Cd complexes are transported into vacuoles. Here, it is shown that Arabidopsis thaliana seedlings defective in the ABCC transporter AtABCC3 (abcc3) have an increased sensitivity to different Cd concentrations, and that seedlings overexpressing AtABCC3 (AtABCC3ox) have an increased Cd tolerance. The cellular distribution of Cd was analysed in protoplasts from abcc3 mutants and AtABCC3 overexpressors grown in the presence of Cd, by means of the Cd-specific fluorochromes 5-nitrobenzothiazole coumarin (BTC-5N) and Leadmium™ Green AM dye. This analysis revealed that Cd is mostly localized in the cytosol of abcc3 mutant protoplasts whereas there is an increase in vacuolar Cd in protoplasts from AtABCC3ox plants. Overexpression of AtABCC3 in cad1-3 mutant seedlings defective in PC production and in plants treated with l-buthionine sulphoximine (BSO), an inhibitor of PC biosynthesis, had no effect on Cd tolerance, suggesting that AtABCC3 acts via PCs. In addition, overexpression of AtABCC3 in atabcc1 atabcc2 mutant seedlings defective in the Cd transporters AtABCC1 and AtABCC2 complements the Cd sensitivity of double mutants, but not in the presence of BSO. Accordingly, the level of AtABCC3 transcript in wild type seedlings was lower than that of AtABCC1 and AtABCC2 in the absence of Cd but higher after Cd exposure, and even higher in atabcc1 atabcc2 mutants. The results point to AtABCC3 as a transporter of PC-Cd complexes, and suggest that its activity is regulated by Cd and is co-ordinated with the activity of AtABCC1/AtABCC2.

  2. Overexpression of rice glutaredoxin OsGrx_C7 and OsGrx_C2.1 reduces intracellular arsenic accumulation and increases tolerance in Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Pankaj Kumar Verma

    2016-06-01

    Full Text Available Glutaredoxins (Grxs are a family of small multifunctional proteins involved in various cellular functions, including redox regulation and protection under oxidative stress. Despite the high number of Grx genes in plant genomes (48 Grxs in rice, the biological functions and physiological roles of most of them remain unknown. Here, the functional characterization of the two arsenic-responsive rice Grx family proteins, OsGrx_C7 and OsGrx_C2.1 are reported. Over-expression of OsGrx_C7 and OsGrx_C2.1 in transgenic Arabidopsis thaliana conferred arsenic (As tolerance as reflected by germination, root growth assay, and whole plant growth. Also, the transgenic expression of OsGrxs displayed significantly reduced As accumulation in A. thaliana seeds and shoot tissues compared to WT plants during both AsIII and AsV stress. Thus, OsGrx_C7 and OsGrx_C2.1 seem to be an important determinant of As-stress response in plants. OsGrx_C7 and OsGrx_C2.1 transgenic showed to maintain intracellular GSH pool and involved in lowering AsIII accumulation either by extrusion or reducing uptake by altering the transcript of A. thaliana AtNIPs. Overall, OsGrx_C7 and OsGrx_C2.1 may represent a Grx family protein involved in As stress response and may allow a better understanding of the As induced stress pathways and the design of strategies for the improvement of stress tolerance as well as decreased As content in crops.

  3. Expression of Stipa purpurea SpCIPK26 in Arabidopsis thaliana Enhances Salt and Drought Tolerance and Regulates Abscisic Acid Signaling

    Directory of Open Access Journals (Sweden)

    Yanli Zhou

    2016-06-01

    Full Text Available Stipa purpurea (S. purpurea is the dominant plant species in the alpine steppe of the Qinghai-Tibet Plateau, China. It is highly resistant to cold and drought conditions. However, the underlying mechanisms regulating the stress tolerance are unknown. In this study, a CIPK gene from S. purpurea (SpCIPK26 was isolated. The SpCIPK26 coding region consisted of 1392 bp that encoded 464 amino acids. The protein has a highly conserved catalytic structure and regulatory domain. The expression of SpCIPK26 was induced by drought and salt stress. SpCIPK26 overexpression in Arabidopsis thaliana (A. thaliana plants provided increased tolerance to drought and salt stress in an abscisic acid (ABA-dependent manner. Compared with wild-type A. thaliana plants, SpCIPK26-overexpressing plants had higher survival rates, water potentials, and photosynthetic efficiency (Fv/Fm, as well as lower levels of reactive oxygen species (ROS following exposure to drought and salt stress. Gene expression analyses indicated stress-inducible genes (RD29A, RD29B, and ABF2 and a ROS-scavenger gene (CAT1 were upregulated in SpCIPK26-overexpressing plants after stress treatments. All of these marker genes are associated with ABA-responsive cis-acting elements. Additionally, the similarities in the gene expression patterns following ABA, mannitol, and NaCl treatments suggest SpCIPK26 has an important role during plant responses to drought and salt stress and in regulating ABA signaling.

  4. The Phosphate Transporter PHT4;6 Is a Determinant of Salt Tolerance that Is Localized to the Golgi Apparatus of Arabidopsis

    Institute of Scientific and Technical Information of China (English)

    Beatriz Cubero; Yuko Nakagawa; Xing-Yu jiang; Ken-Ji Miura; Fang Li; Kashchandra G.Raghothama; Ray A.Bressan; Paul M.Hasegawa; Jose M.Pardo

    2009-01-01

    Insertion mutations that disrupt the function of PHT4;6 (At5g44370) cause NaCI hypersensitivity of Arabidop-sis seedlings that is characterized by reduced growth of the primary root,enhanced lateral branching,and swelling of root tips.Mutant phenotypes were exacerbated by sucrose,but not by equiosmolar concentrations of mannitol,and atten-uated by low inorganic phosphate in the medium.Protein PHT4;6 belongs to the Major Facilitator Superfamily of per-meases that shares significant sequence similarity to mammalian type-I Pi transporters and vesicular glutamate transporters,and is a member of the PHT4 family of putative intracellular phosphate transporters of plants.PHT4;6 local-izes to the Golgi membrane and transport studies indicate that PHT4;6 facilitates the selective transport of Pi but not of chloride or inorganic anions.Phenotypic similarities with other mutants displaying root swelling suggest that PHT4;6 likely functions in protein N-glycosylation and cell wall biosynthesis,which are essential for salt tolerance.Together,our results indicate that PHT4;6 transports Pi out of the Golgi lumenal space for the re-cycling of the Pi released from glycosylation processes.

  5. Constitutive over-expression of rice chymotrypsin protease inhibitor gene OCPI2 results in enhanced growth, salinity and osmotic stress tolerance of the transgenic Arabidopsis plants.

    Science.gov (United States)

    Tiwari, Lalit Dev; Mittal, Dheeraj; Chandra Mishra, Ratnesh; Grover, Anil

    2015-07-01

    Protease inhibitors are involved primarily in defense against pathogens. In recent years, these proteins have also been widely implicated in response of plants to diverse abiotic stresses. Rice chymotrypsin protease inhibitor gene OCPI2 is highly induced under salt and osmotic stresses. The construct containing the complete coding sequence of OCPI2 cloned downstream to CaMV35S promoter was transformed in Arabidopsis and single copy, homozygous transgenic lines were produced. The transgenic plants exhibited significantly enhanced tolerance to NaCl, PEG and mannitol stress as compared to wild type plants. Importantly, the vegetative and reproductive growth of transgenic plants under unstressed, control conditions was also enhanced: transgenic plants were more vigorous than wild type, resulting into higher yield in terms of silique number. The RWC values and membrane stability index of transgenic in comparison to wild type plants was higher. Higher proline content was observed in the AtOCPI2 lines, which was associated with higher transcript expression of pyrroline-5-carboxylate synthase and lowered levels of proline dehydrogenase genes. The chymotrypsin protease activities were lower in the transgenic as against wild type plants, under both unstressed, control as well as stressed conditions. It thus appears that rice chymotrypsin protease inhibitor gene OCPI2 is a useful candidate gene for genetic improvement of plants against salt and osmotic stress.

  6. Ectopic expression of a stress-inducible glycosyltransferase from saffron enhances salt and oxidative stress tolerance in Arabidopsis while alters anchor root formation.

    Science.gov (United States)

    Ahrazem, Oussama; Rubio-Moraga, Angela; Trapero-Mozos, Almudena; Climent, María Fernanda López; Gómez-Cadenas, Aurelio; Gómez-Gómez, Lourdes

    2015-05-01

    Glycosyltransferases play diverse roles in cellular metabolism by modifying the activities of regulatory metabolites. Three stress-regulated UDP-glucosyltransferase-encoding genes have been isolated from the stigmas of saffron, UGT85U1, UGT85U2 and UGT85V1, which belong to the UGT85 family that includes members associated with stress responses and cell cycle regulation. Arabidopsis constitutively expressing UGT85U1 exhibited and increased anchor root development. No differences were observed in the timing of root emergence, in leaf, stem and flower morphology or flowering time. However, salt and oxidative stress tolerance was enhanced in these plants. Levels of glycosylated compounds were measured in these plants and showed changes in the composition of several indole-derivatives. Moreover, auxin levels in the roots were higher compared to wild type. The expression of several key genes related to root development and auxin homeostasis, including CDKB2.1, CDKB2.2, PIN2, 3 and 4; TIR1, SHR, and CYCD6, were differentially regulated with an increase of expression level of SHR, CYCD6, CDKB2.1 and PIN2. The obtained results showed that UGT85U1 takes part in root growth regulation via auxin signal alteration and the modified expression of cell cycle-related genes, resulting in significantly improved survival during oxidative and salt stress treatments.

  7. Co-overexpressing a plasma membrane and a vacuolar membrane sodium/proton antiporter significantly improves salt tolerance in transgenic Arabidopsis plants.

    Science.gov (United States)

    The Arabidopsis gene AtNHX1 encodes a vacuolar membrane bound sodium/proton (Sodium/Hydrogen) antiporter that transports sodium into the vacuole and exports hydrogen into the cytoplasm. The Arabidopsis gene SOS1 encodes a plasma membrane bound sodium/hydrogen antiporter that exports sodium to the ex...

  8. Vacuolar H(+)-Pyrophosphatase AVP1 is Involved in Amine Fungicide Tolerance in Arabidopsis thaliana and Provides Tridemorph Resistance in Yeast.

    Science.gov (United States)

    Hernández, Agustín; Herrera-Palau, Rosana; Madroñal, Juan M; Albi, Tomás; López-Lluch, Guillermo; Perez-Castiñeira, José R; Navas, Plácido; Valverde, Federico; Serrano, Aurelio

    2016-01-01

    Amine fungicides are widely used as crop protectants. Their success is believed to be related to their ability to inhibit postlanosterol sterol biosynthesis in fungi, in particular sterol-Δ(8),Δ(7)-isomerases and sterol-Δ(14)-reductases, with a concomitant accumulation of toxic abnormal sterols. However, their actual cellular effects and mechanisms of death induction are still poorly understood. Paradoxically, plants exhibit a natural resistance to amine fungicides although they have similar enzymes in postcicloartenol sterol biosynthesis that are also susceptible to fungicide inhibition. A major difference in vacuolar ion homeostasis between plants and fungi is the presence of a dual set of primary proton pumps in the former (V-ATPase and H(+)-pyrophosphatase), but only the V-ATPase in the latter. Abnormal sterols affect the proton-pumping capacity of V-ATPases in fungi and this has been proposed as a major determinant in fungicide action. Using Saccharomyces cerevisiae as a model fungus, we provide evidence that amine fungicide treatment induced cell death by apoptosis. Cell death was concomitant with impaired H(+)-pumping capacity in vacuole vesicles and dependent on vacuolar proteases. Also, the heterologous expression of the Arabidopsis thaliana main H(+)-pyrophosphatase (AVP1) at the fungal vacuolar membrane reduced apoptosis levels in yeast and increased resistance to amine fungicides. Consistently, A. thaliana avp1 mutant seedlings showed increased susceptibility to this amine fungicide, particularly at the level of root development. This is in agreement with AVP1 being nearly the sole H(+)-pyrophosphatase gene expressed at the root elongation zones. All in all, the present data suggest that H(+)-pyrophosphatases are major determinants of plant tolerance to amine fungicides.

  9. Overexpression of Crocus carotenoid cleavage dioxygenase, CsCCD4b, in Arabidopsis imparts tolerance to dehydration, salt and oxidative stresses by modulating ROS machinery.

    Science.gov (United States)

    Baba, Shoib Ahmad; Jain, Deepti; Abbas, Nazia; Ashraf, Nasheeman

    2015-09-15

    Apocarotenoids modulate vital physiological and developmental processes in plants. These molecules are formed by the cleavage of carotenoids, a reaction catalyzed by a family of enzymes called carotenoid cleavage dioxygenases (CCDs). Apocarotenoids like β-ionone and β-cyclocitral have been reported to act as stress signal molecules during high light stress in many plant species. In Crocus sativus, these two apocarotenoids are formed by enzymatic cleavage of β-carotene at 9, 10 and 7, 8 bonds by CsCCD4 enzymes. In the present study three isoforms of CsCCD4 were subjected to molecular modeling and docking analysis to determine their substrate specificity and all the three isoforms displayed high substrate specificity for β-carotene. Further, expression of these three CsCCD4 isoforms investigated in response to various stresses revealed that CsCCD4a and CsCCD4b exhibit enhanced expression in response to dehydration, salt and methylviologen, providing a clue towards their role in mediating plant defense response. This was confirmed by overexpressing CsCCD4b in Arabidopsis. The transgenic plants developed longer roots and possessed higher number of lateral roots. Further, overexpression of CsCCD4b imparted enhanced tolerance to salt, dehydration and oxidative stresses as was evidenced by higher survival rate, increased relative root length and biomass in transgenic plants as compared to wild type. Transgenic plants also displayed higher activity and expression of reactive oxygen species (ROS) metabolizing enzymes. This indicates that β-ionone and β-cyclocitral which are enzymatic products of CsCCD4b may act as stress signals and mediate reprogramming of stress responsive genes which ultimately leads to plant defense.

  10. Arabidopsis LOS5/ABA3 overexpression in transgenic tobacco (Nicotiana tabacum cv. Xanthi-nc) results in enhanced drought tolerance.

    Science.gov (United States)

    Yue, Yuesen; Zhang, Mingcai; Zhang, Jiachang; Duan, Liusheng; Li, Zhaohu

    2011-10-01

    Drought is a major environmental stress factor that affects growth and development of plants. Abscisic acid (ABA), osmotically active compounds, and synthesis of specific proteins, such as proteins that scavenge oxygen radicals, are crucial for plants to adapt to water deficit. LOS5/ABA3 (LOS5) encodes molybdenum-cofactor sulfurase, which is a key regulator of ABA biosynthesis. We overexpressed LOS5 in tobacco using Agrobacterium-mediated transformation. Detached leaves of LOS5-overexpressing seedlings showed lower transpirational water loss than that of nontransgenic seedlings in the same period under normal conditions. When subjected to water-deficit stress, transgenic plants showed less wilting, maintained higher water content and better cellular membrane integrity, accumulated higher quantities of ABA and proline, and exhibited higher activities of antioxidant enzymes, i.e., superoxide dismutase, catalase, peroxidase and ascorbate peroxidase, as compared with control plants. Furthermore, LOS5-overexpressing plants treated with 30% polyethylene glycol showed similar performance in cellular membrane protection, ABA and proline accumulation, and activities of catalase and peroxidase to those under drought stress. Thus, overexpression of LOS5 in transgenic tobacco can enhance drought tolerance.

  11. Constitutive Overexpression of Myo-inositol-1-Phosphate Synthase Gene (GsMIPS2) fromGlycine soja Confers Enhanced Salt Tolerance at Various Growth Stages inArabidopsis

    Institute of Scientific and Technical Information of China (English)

    Zaib-un-Nisa; Chen Chen; Yang Yu; Chao Chen; ALi Inayat Mallano; Duan Xiang-bo; Sun Xiao-li; Zhu Yan-ming

    2016-01-01

    The enzymemyo-inositol-1-phosphate synthase (MIPS EC 5.5.1.4) catalyzes the first step ofmyo-inositol biosynthesis, a product that plays crucial roles in plants as an osmoprotectant, transduction molecule, cell wall constituent and production of stress related molecule. Previous reports highlighted an important role of MIPS family genes in abiotic stresses particularly under salt stress tolerance in several plant species; however, little is known about the cellular and physiological functions ofMIPS2 genes under abiotic conditions. In this study, a novel salt stress responsive gene designatedGsMIPS2 from wild soybean Glycine soja07256 was functionally characterized contained an open reading frame (ORF) of 1 533 bp coding a peptide sequence of 510 amino acids along with mass of 56 445 ku. Multiple sequence alignment analysis revealed its 92%-99% similarity with other MIPS family members in legume proteins. Quantitative real-time PCR results demonstrated thatGsMIPS2 was induced by salt stress and expressed in roots of soybean. The positive function ofGsMIPS2 under salt response at different growth stages of transgenicArabidopsis was also elucidated. The results showed thatGsMIPS2 transgenic lines displayed increased tolerance as compared to WT andatmips2 mutant lines under salt stress. Furthermore, the expression levels of some salt stress responsive marker genes, including KIN1,RD29A, RD29B,P5CsandCOR47 were significantly up-regulated inGsMIPS2 overexpression lines than wild type andatmips2 mutant. Collectively, these results suggested thatGsMIPS2 gene was a positive regulator of plant tolerance to salt stress. This was the first report to demonstrate that overexpression ofGsMIPS2 gene from wild soybean improved salt tolerance in transgenicArabidopsis.

  12. Older Thinopyrum intermedium (Poaceae) plants exhibit superior photosynthetic tolerance to cold stress and greater increases in two photosynthetic enzymes under freezing stress compared with young plants.

    Science.gov (United States)

    Jaikumar, Nikhil S; Snapp, Sieglinde S; Sharkey, Thomas D

    2016-08-01

    Effects of plant age on resource acquisition and stress tolerance processes is a largely unstudied subject in herbaceous perennials. In a field experiment, we compared rates of photosynthesis (A), ribulose-1,5-bisphosphate (RuBP) carboxylation capacity (V Cmax), maximum electron transport rate (J max), and triose phosphate utilization (TPU), as well as concentrations of Rubisco and sucrose-phosphate synthase (SPS) in 5-year-old and 2-year-old intermediate wheatgrass (Thinopyrum intermedium) under both optimal growing conditions and cold stress in early spring and autumn. This species is a relative of wheat undergoing domestication. An additional experiment compared photosynthetic rates in different cohorts at mid-season and under colder conditions. We hypothesized that photosynthetic capacity in older plants would be lower under favorable conditions but higher under cold stress. Our hypothesis was generally supported. Under cold stress, 5-year-old plants exhibited higher A, TPU, and temperature-adjusted V Cmax than younger plants, as well as 50% more SPS and 37% more Rubisco. In contrast, at mid-season, photosynthetic capacities in older plants were lower than in younger plants in one experiment, and similar in the other, independent of differences in water status. Both cohorts increased A, temperature-adjusted TPU and J max, [Rubisco], and [SPS] under cold stress, but changes were greater in older plants. Photosynthetic differences were largest at 1.2 ºC in very early spring, where older plants had 200% higher A and maintained up to 17% of their peak photosynthetic capacity. We find evidence of increased cold tolerance in older cohorts of wheatgrass, consistent with a growing body of research in woody perennials.

  13. Freeze fracture and freeze etching.

    Science.gov (United States)

    Chandler, Douglas E; Sharp, William P

    2014-01-01

    Freeze fracture depends on the property of frozen tissues or cells, when cracked open, to split along the hydrophobic interior of membranes, thus revealing broad panoramas of membrane interior. These large panoramas reveal the three-dimensional contours of membranes making the methods well suited to studying changes in membrane architecture. Freshly split membrane faces are visualized by platinum or tungsten shadowing and carbon backing to form a replica that is then cleaned of tissue and imaged by TEM. Etching, i.e., removal of ice from the frozen fractured specimen by sublimation prior to shadowing, can also reveal the true surfaces of the membrane as well as the extracellular matrix and cytoskeletal networks that contact the membranes. Since the resolution of detail in the metal replicas formed is 1-2 nm, these methods can also be used to visualize macromolecules or macromolecular assemblies either in situ or displayed on a mica surface. These methods are available for either specimens that have been chemically fixed or specimens that have been rapidly frozen without chemical intervention.

  14. Effects of Endogenous and/or Exogenous Trehalose on Freezing-tolerance of Baker's Yeast%内源与(或)外源海藻糖对面包酵母耐冷冻性的影响研究

    Institute of Scientific and Technical Information of China (English)

    王碧莹; 孙溪; 肖冬光

    2015-01-01

    通过测定胞内海藻糖降解、冷冻前后细胞存活率以及发酵力的变化,研究内源与(或)外源海藻糖对面包酵母耐冷冻性的影响。结果表明,含有较高内源海藻糖的BY14α+Tps1菌株具有更高的冷冻后细胞生存率与发酵力。外源添加5%海藻糖仅能改善较低胞内基本海藻糖含量(<10%)菌株的耐冷冻性,并且预发酵过程中海藻糖的稳定性较差(尤其前15 min)。因此,使用内源法提高胞内海藻糖含量对提升面包酵母的耐冷冻性更具可行性。%The effects of endogenous and/or exogenous trehalose on freezing-tolerance of baker's yeast were investigated through the measure-ment of cell viability and fermenting power before and after intracellular trehalose hydrolysis and freezing. The experimental results showed that BY14α+Tps1 strain with higher content of endogenous trehalose had higher cell viability and fermenting power after the freezing, and the added exogenous trehalose at the concentration of 5%could only improve the freezing-tolerance of cells with low trehalose content (<10%) but the added exogenous trehalose was apparently unstable in the prefermentation process (especially at the first 15 min after inoculation). Therefore, the method of improving endogenous trehalose in cells were feasible to strengthen freezing tolerance of baker's yeast.

  15. Freezing and Food Safety

    Science.gov (United States)

    ... and Food Safety What Can You Freeze? Is Frozen Food Safe? Does Freezing Destroy Bacteria & Parasites? Freshness & Quality ... Temperatures Freezer Storage Time Safe Thawing Refreezing Cooking Frozen Foods Power Outage in Freezer Frozen Cans Frozen Eggs ...

  16. Ectopic phytocystatin expression leads to enhanced drought stress tolerance in soybean (Glycine max) and Arabidopsis thaliana through effects on strigolactone pathways and can also result in improved seed traits.

    Science.gov (United States)

    Quain, Marian D; Makgopa, Matome E; Márquez-García, Belén; Comadira, Gloria; Fernandez-Garcia, Nieves; Olmos, Enrique; Schnaubelt, Daniel; Kunert, Karl J; Foyer, Christine H

    2014-09-01

    Ectopic cystatin expression has long been used in plant pest management, but the cysteine protease, targets of these inhibitors, might also have important functions in the control of plant lifespan and stress tolerance that remain poorly characterized. We therefore characterized the effects of expression of the rice cystatin, oryzacystatin-I (OCI), on the growth, development and stress tolerance of crop (soybean) and model (Arabidopsis thaliana) plants. Ectopic OCI expression in soybean enhanced shoot branching and leaf chlorophyll accumulation at later stages of vegetative development and enhanced seed protein contents and decreased the abundance of mRNAs encoding strigolactone synthesis enzymes. The OCI-expressing A. thaliana showed a slow-growth phenotype, with increased leaf numbers and enhanced shoot branching at flowering. The OCI-dependent inhibition of cysteine proteases enhanced drought tolerance in soybean and A. thaliana, photosynthetic CO2 assimilation being much less sensitive to drought-induced inhibition in the OCI-expressing soybean lines. Ectopic OCI expression or treatment with the cysteine protease inhibitor E64 increased lateral root densities in A. thaliana. E64 treatment also increased lateral root densities in the max2-1 mutants that are defective in strigolactone signalling, but not in the max3-9 mutants that are defective in strigolactone synthesis. Taken together, these data provide evidence that OCI-inhibited cysteine proteases participate in the control of growth and stress tolerance through effects on strigolactones. We conclude that cysteine proteases are important targets for manipulation of plant growth, development and stress tolerance, and also seed quality traits.

  17. Transgenic salt-tolerant sugar beet (Beta vulgaris L.) constitutively expressing an Arabidopsis thaliana vacuolar Na/H antiporter gene, AtNHX3, accumulates more soluble sugar but less salt in storage roots.

    Science.gov (United States)

    Liu, Hua; Wang, Qiuqing; Yu, Mengmeng; Zhang, Yanyan; Wu, Yingbao; Zhang, Hongxia

    2008-09-01

    In Arabidopsis thaliana, six vacuolar Na(+)/H(+) antiporters (AtNHX1-6) were identified. Among them, AtNHX1, 2 and 5 are functional Na(+)/H(+) antiporters with the most abundant expression levels in seedling shoots and roots. However, the expression of AtNHX3 in Arabidopsis can only be detected by RT-PCR, and its physiological function still remains unclear. In this work, we demonstrate that constitutive expression of AtNHX3 in sugar beet (Beta vulgaris L.) conferred augmented resistance to high salinity on transgenic plants. In the presence of 300 or 500 mm NaCl, transgenic plants showed very high potassium accumulation in the roots and storage roots. Furthermore, the transcripts of sucrose phosphate synthase (SPS), sucrose synthase (SS) and cell wall sucrose invertase (SI) genes were maintained in transgenic plants. The accumulation of soluble sugar in the storage roots of transgenic plants grown under high salt stress condition was also higher. Our results implicate that AtNHX3 is also a functional antiporter responsible for salt tolerance by mediating K(+)/H(+) exchange in higher plants. The salt accumulation in leaves but not in the storage roots, and the increased yield of storage roots with enhanced constituent soluble sugar contents under salt stress condition demonstrate a great potential use of this gene in improving the quality and yield of crop plants.

  18. Identification of the trehalose-6-phosphate synthase gene family in winter wheat and expression analysis under conditions of freezing stress

    Indian Academy of Sciences (India)

    D. W. Xie; X. N. Wang; L. S. Fu; J. Sun; W. Zheng; Z. F. Li

    2015-03-01

    Trehalose plays an important role in metabolic regulation and abiotic stress tolerance in plants. Trehalose contents are potentially modulated by trehalose-6-phosphate synthase (TPS), which is a key enzyme in the trehalose biosynthetic pathway. Using available wheat expressed sequence tag sequence information from NCBI and two wheat genome databases, we identified 12 wheat TPS genes and performed a comprehensive study on their structural, evolutionary and functional properties. The estimated divergence time of wheat TPS gene pairs and wheat–rice orthologues suggested that wheat and rice have a common ancestor. The number of TPS genes in the wheat genome was estimated to be at least 12, which is close to the number found in rice, Arabidopsis and soybean. Moreover, it has been reported earlier in other plants that TPS genes respond to abiotic stress, however, our study mainly analysed the TPS gene family under freezing conditions in winter wheat, and determined that most of the TPS gene expression in winter wheat was induced by freezing conditions, which further suggested that wheat TPS genes were involved in winter wheat freeze-resistance signal transduction pathways. Taken together, the current study represents the first comprehensive study of TPS genes in winter wheat and provides a foundation for future functional studies of this important gene family in Triticeae.

  19. Heterologous expression of the gourd E3 ubiquitin ligase gene LsRZF1 compromises the drought stress tolerance in Arabidopsis thaliana.

    Science.gov (United States)

    Min, Ji-Hee; Ju, Hyun-Woo; Yang, Kwang-Yeol; Chung, Jung-Sung; Cho, Baik-Ho; Kim, Cheol Soo

    2014-04-01

    Protein ubiquitination is one of the major regulatory processes used by eukaryotic cells. The ubiquitin E3 ligase acts as a main determinant of substrate specificity. However, the precise roles of E3 ligase in plants to drought stress are poorly understood. In this study, a gourd family (Lagenaria siceraria) ortholog of Arabidopsis thaliana RING Zinc Finger 1 (AtRZF1) gene, designated LsRZF1, was identified and characterized. LsRZF1 was reduced by abscisic acid (ABA), osmotic stress, and drought conditions. Compared to wild type, transgenic Arabidopsis plants ectopic expressing LsRZF1 were hypersensitive to ABA and osmotic stress during early seedling development, indicating that LsRZF1 negatively regulates drought-mediated control of early seedling development. Moreover, the ectopic expression of the LsRZF1 gene was very influential in drought sensitive parameters including proline content, water loss, and the expression of dehydration stress-related genes. Furthermore, ubiquitin E3 ligase activity and genetic data indicate that AtRZF1 and LsRZF1 function in similar pathway to control proline metabolism in Arabidopsis under drought condition. Together, these results suggest that the E3 ligase LsRZF1 is an important regulator of water deficit stress during early seedling development.

  20. The salty tale of Arabidopsis.

    Science.gov (United States)

    Sanders, D

    2000-06-29

    High concentrations of sodium chloride are toxic to most plant species. New insights into the mechanisms by which plants tolerate salt have emerged from the identification of genes in Arabidopsis thaliana that play a critical part in physiological resistance to salt.

  1. Expression of Caenorhabditis elegans PCS in the AtPCS1-deficient Arabidopsis thaliana cad1-3 mutant separates the metal tolerance and non-host resistance functions of phytochelatin synthases.

    Science.gov (United States)

    Kühnlenz, Tanja; Westphal, Lore; Schmidt, Holger; Scheel, Dierk; Clemens, Stephan

    2015-11-01

    Phytochelatin synthases (PCS) play key roles in plant metal tolerance. They synthesize small metal-binding peptides, phytochelatins, under conditions of metal excess. Respective mutants are strongly cadmium and arsenic hypersensitive. However, their ubiquitous presence and constitutive expression had long suggested a more general function of PCS besides metal detoxification. Indeed, phytochelatin synthase1 from Arabidopsis thaliana (AtPCS1) was later implicated in non-host resistance. The two different physiological functions may be attributable to the two distinct catalytic activities demonstrated for AtPCS1, that is the dipeptidyl transfer onto an acceptor molecule in phytochelatin synthesis, and the proteolytic deglycylation of glutathione conjugates. In order to test this hypothesis and to possibly separate the two biological roles, we expressed a phylogenetically distant PCS from Caenorhabditis elegans in an AtPCS1 mutant. We confirmed the involvement of AtPCS1 in non-host resistance by showing that plants lacking the functional gene develop a strong cell death phenotype when inoculated with the potato pathogen Phytophthora infestans. Furthermore, we found that the C. elegans gene rescues phytochelatin synthesis and cadmium tolerance, but not the defect in non-host resistance. This strongly suggests that the second enzymatic function of AtPCS1, which remains to be defined in detail, is underlying the plant immunity function.

  2. Salt tolerance conferred by overexpression of Arabidopsis vacuolar Na(+)/H (+) antiporter gene AtNHX1 in common buckwheat (Fagopyrum esculentum).

    Science.gov (United States)

    Chen, Li-Hong; Zhang, Bo; Xu, Zi-Qin

    2008-02-01

    Agriculture productivity is severely affected by soil salinity. One possible mechanism by which plants could survive salt stress is to compartmentalize sodium ions away from the cytosol. In the present work, transgenic buckwheat plants overexpressing AtNHX1, a vacuolar Na(+)/H(+) antiporter gene from Arabidopsis thaliana, were regenerated after transformation with Agrobacterium tumefaciens. These plants were able to grow, flower and accumulate more rutin in the presence of 200 mmol/l sodium chloride. Moreover, the content of important nutrients in buckwheat was not affected by the high salinity of the soil. These results demonstrated the potential value of these transgenic plants for agriculture use in saline soil.

  3. Overexpression of the autophagy-related gene SiATG8a from foxtail millet (Setaria italica L.) confers tolerance to both nitrogen starvation and drought stress in Arabidopsis.

    Science.gov (United States)

    Li, Wei-wei; Chen, Ming; Zhong, Li; Liu, Jia-ming; Xu, Zhao-shi; Li, Lian-cheng; Zhou, Yong-Bin; Guo, Chang-Hong; Ma, You-Zhi

    2015-12-25

    Autophagy is an evolutionarily conserved biological process in all eukaryotes for the degradation of intracellular components for nutrient recycling. Autophagy is known to be involved in responses to low nitrogen stress in Arabidopsis. Foxtail millet has strong abiotic stress resistance to both low nutrient and drought stress. However, to date, there have only been a few genes reported to be related with abiotic stress resistance in foxtail millet. In this study, we identified an autophagy-related gene, SiATG8a, from foxtail millet. SiATG8a is mainly expressed in stems and its expression was dramatically induced by drought stress and nitrogen starvation treatments. SiATG8a was localized in the membrane and cytoplasm of foxtail millet. Overexpression of SiATG8a in Arabidopsis conferred tolerance to both nitrogen starvation and to drought stress. Under nitrogen starvation conditions, the SiATG8a transgenic plants had larger root and leaf areas and accumulated more total nitrogen than wild-type plants. The transgenic plants had lower total protein concentrations than did the WT plants. Under drought stress, the SiATG8a transgenic plants had higher survival rates, chlorophyll content, and proline content, but had lower MDA content than wild type plants. Taken together, our results represent the first identified case where overexpression of autophagy related gene can simultaneously improve plant resistance to low nitrogen and drought stresses. These findings implicate plant autophagy in plant stress responses to low nitrogen and drought and should be helpful in efforts to improve stresses resistance to nitrogen starvation and drought of crops by genetic transformation.

  4. Over-expression of a tomato N-acetyl-L-glutamate synthase gene (SlNAGS1) in Arabidopsis thaliana results in high ornithine levels and increased tolerance in salt and drought stresses.

    Science.gov (United States)

    Kalamaki, Mary S; Alexandrou, Dimitris; Lazari, Diamanto; Merkouropoulos, Georgios; Fotopoulos, Vasileios; Pateraki, Irene; Aggelis, Alexandros; Carrillo-López, Armando; Rubio-Cabetas, Maria J; Kanellis, Angelos K

    2009-01-01

    A single copy of the N-acetyl-L-glutamate synthase gene (SlNAGS1) has been isolated from tomato. The deduced amino acid sequence consists of 604 amino acids and shows a high level of similarity to the predicted Arabidopsis NAGS1 and NAGS2 proteins. Furthermore, the N-terminus ArgB domain and the C-terminus ArgA domain found in SlNAGS1 are similar to the structural arrangements that have been reported for other predicted NAGS proteins. SlNAGS1 was expressed at high levels in all aerial organs, and at basic levels in seeds, whereas it was not detected at all in roots. SlNAGS1 transcript accumulation was noticed transiently in tomato fruit at the red-fruit stage. In addition, an increase of SlNAGS1 transcripts was detected in mature green tomato fruit within the first hour of exposure to low oxygen concentrations. Transgenic Arabidopsis plants have been generated expressing the SlNAGS1 gene under the control of the cauliflower mosaic virus (CaMV) 35S promoter. Three homozygous transgenic lines expressing the transgene (lines 1-7, 3-8, and 6-5) were evaluated further. All three transgenic lines showed a significant accumulation of ornithine in the leaves with line 3-8 exhibiting the highest concentration. The same lines demonstrated higher germination ability compared to wild-type (WT) plants when subjected to 250 mM NaCl. Similarly, mature plants of all three transgenic lines displayed a higher tolerance to salt and drought stress compared to WT plants. Under most experimental conditions, transgenic line 3-8 performed best, while the responses obtained from lines 1-7 and 6-5 depended on the applied stimulus. To our knowledge, this is the first plant NAGS gene to be isolated, characterized, and genetically modified.

  5. SIZ1 deficiency causes reduced stomatal aperture and enhanced drought tolerance via controlling salicylic acid-induced accumulation of reactive oxygen species in Arabidopsis.

    Science.gov (United States)

    Miura, Kenji; Okamoto, Hiroyuki; Okuma, Eiji; Shiba, Hayato; Kamada, Hiroshi; Hasegawa, Paul M; Murata, Yoshiyuki

    2013-01-01

    Transpiration and gas exchange occur through stomata. Thus, the control of stomatal aperture is important for the efficiency and regulation of water use, and for the response to drought. Here, we demonstrate that SIZ1-mediated endogenous salicylic acid (SA) accumulation plays an important role in stomatal closure and drought tolerance. siz1 reduced stomatal apertures. The reduced stomatal apertures of siz1 were inhibited by the application of peroxidase inhibitors, salicylhydroxamic acid and azide, which inhibits SA-dependent reactive oxygen species (ROS) production, but not by an NADPH oxidase inhibitor, diphenyl iodonium chloride, which inhibits ABA-dependent ROS production. Furthermore, the introduction of nahG into siz1, which reduces SA accumulation, restored stomatal opening. Stomatal closure is generally induced by water deficit. The siz1 mutation caused drought tolerance, whereas nahG siz1 suppressed the tolerant phenotype. Drought stresses also induced expression of SA-responsive genes, such as PR1 and PR2. Furthermore, other SA-accumulating mutants, cpr5 and acd6, exhibited stomatal closure and drought tolerance, and nahG suppressed the phenotype of cpr5 and acd6, as did siz1 and nahG siz1. Together, these results suggest that SIZ1 negatively affects stomatal closure and drought tolerance through the accumulation of SA.

  6. Disruption of AtWNK8 Enhances Tolerance of Arabidopsis to Salt and Osmotic Stresses via Modulating Proline Content and Activities of Catalase and Peroxidase

    Directory of Open Access Journals (Sweden)

    Hong Liao

    2013-03-01

    Full Text Available With no lysine kinases (WNKs play important roles in plant growth and development. However, its role in salt and osmotic stress tolerance is unclear. Here, we report that AtWNK8 is mainly expressed in primary root, hypocotyl, stamen and pistil and is induced by NaCl and sorbitol treatment. Compared to the wild-type, the T-DNA knock-out wnk8 mutant was more tolerant to severe salinity and osmotic stresses, as indicated by 27% and 198% more fresh weight in the NaCl and sorbitol treatment, respectively. The wnk8 mutant also accumulated 1.43-fold more proline than the wild-type in the sorbitol treatment. Under NaCl and sorbitol stresses, catalase (CAT activity in wnk8 mutant was 1.92- and 3.7-times of that in Col-0, respectively. Similarly, under salt and osmotic stress conditions, peroxidase (POD activities in wnk8 mutant were 1.81- and 1.58-times of that in Col-0, respectively. Taken together, we revealed that maintaining higher CAT and POD activities might be one of the reasons that the disruption of AtWNK8 enhances the tolerance to salt stress, and accumulating more proline and higher activities of CAT and POD might result in the higher tolerance of WNK8 to osmotic stress.

  7. Reversible Photoinhibition in Antarctic Moss during Freezing and Thawing.

    Science.gov (United States)

    Lovelock, C. E.; Jackson, A. E.; Melick, D. R.; Seppelt, R. D.

    1995-01-01

    Tolerance of antarctic moss to freezing and thawing stress was investigated using chlorophyll a fluorescence. Freezing in darkness caused reductions in Fv/Fm (ratio of variable to maximum fluorescence) and Fo (initial fluorescence) that were reversible upon thawing. Reductions in Fv/Fm and Fo during freezing in darkness indicate a reduction in the potential efficiency of photosystem II that may be due to conformational changes in pigment-protein complexes due to desiccation associated with freezing. The absorption of light during freezing further reduced Fv/Fm and Fo but was also reversible. Using dithiothreitol (DTT), which inhibits the formation of the carotenoid zeaxanthin, we found reduced flurorescence quenching during freezing and reduced concentrations of zeaxanthin and antheraxanthin after freezing in DTT-treated moss. Reduced concentrations of zeaxanthin and antheraxanthin in DTT-treated moss were partially associated with reductions in nonphotochemical fluorescence quenching. The reversible photoinhibition observed in antarctic moss during freezing indicates the existence of processes that protect from photoinhibitory damage in environments where freezing temperatures occur in conjunction with high solar radiation levels. These processes may limit the need for repair cycles that require temperatures favorable for enzyme activity. PMID:12228644

  8. Summer freezing resistance: a critical filter for plant community assemblies in Mediterranean high mountains

    Directory of Open Access Journals (Sweden)

    David Sánchez Pescador

    2016-02-01

    Full Text Available Assessing freezing community response and whether freezing resistance is related to other functional traits is essential for understanding alpine community assemblages, particularly in Mediterranean environments where plants are exposed to freezing temperatures and summer droughts. Thus, we characterized the leaf freezing resistance of 42 plant species in 38 plots at Sierra de Guadarrama (Spain by measuring their ice nucleation temperature, freezing point (FP, and low-temperature damage (LT50, as well as determining their freezing resistance mechanisms (i.e., tolerance or avoidance. The community response to freezing was estimated for each plot as community weighted means (CWMs and functional diversity, and we assessed their relative importance with altitude. We established the relationships between freezing resistance, growth forms, and four key plant functional traits (i.e., plant height, specific leaf area, leaf dry matter content, and seed mass. There was a wide range of freezing resistance responses and more than in other alpine habitats. At the community level, the CWMs of FP and LT50 responded negatively to altitude, whereas the functional diversity of both traits increased with altitude. The proportion of freezing-tolerant species also increased with altitude. The ranges of FP and LT50 varied among growth forms, and only the leaf dry matter content correlated negatively with freezing-resistance traits. Summer freezing events represent important abiotic filters for assemblies of Mediterranean high mountain communities, as suggested by the CWMs. However, a concomitant summer drought constraint may also explain the high freezing resistance of species that thrive in these areas and the lower functional diversity of freezing resistance traits at lower altitudes. Leaves with high dry matter contents may maintain turgor at lower water potential and enhance drought tolerance in parallel to freezing resistance. This adaptation to drought seems to

  9. Stability of small ubiquitin-like modifier (SUMO) proteases OVERLY TOLERANT TO SALT1 and -2 modulates salicylic acid signalling and SUMO1/2 conjugation in Arabidopsis thaliana.

    Science.gov (United States)

    Bailey, Mark; Srivastava, Anjil; Conti, Lucio; Nelis, Stuart; Zhang, Cunjin; Florance, Hannah; Love, Andrew; Milner, Joel; Napier, Richard; Grant, Murray; Sadanandom, Ari

    2016-01-01

    Small ubiquitin-like modifier proteases 1 and 2 (SUMO1/2) have been linked to the regulation of salicylic acid (SA)-mediated defence signalling in Arabidopsis thaliana. In order to define the role of the SUMO proteases OVERLY TOLERANT TO SALT1 and -2 (OTS1/2) in defence and to provide insight into SUMO1/2-mediated regulation of SA signalling, we examined the status of SA-mediated defences in ots1/2 mutants. The ots1 ots2 double mutant displayed enhanced resistance to virulent Pseudomonas syringae and higher levels of SA compared with wild-type (WT) plants. Furthermore, ots1 ots2 mutants exhibited upregulated expression of the SA biosynthesis gene ICS1 in addition to enhanced SA-responsive ICS1 expression beyond that of WT. SA stimulated OTS1/2 degradation and promoted accumulation of SUMO1/2 conjugates. These results indicate that OTS1 and -2 act in a feedback loop in SA signalling and that de novo OTS1/2 synthesis works antagonistically to SA-promoted degradation, adjusting the abundance of OTS1/2 to moderate SA signalling. Accumulation of SUMO1/2 conjugates coincides with SA-promoted OTS degradation and may play a positive role in SA-mediated signalling in addition to its repressive roles reported elsewhere.

  10. The BEACH Domain Protein SPIRRIG Is Essential for Arabidopsis Salt Stress Tolerance and Functions as a Regulator of Transcript Stabilization and Localization.

    Directory of Open Access Journals (Sweden)

    Alexandra Steffens

    2015-07-01

    Full Text Available Members of the highly conserved class of BEACH domain containing proteins (BDCPs have been established as broad facilitators of protein-protein interactions and membrane dynamics in the context of human diseases like albinism, bleeding diathesis, impaired cellular immunity, cancer predisposition, and neurological dysfunctions. Also, the Arabidopsis thaliana BDCP SPIRRIG (SPI is important for membrane integrity, as spi mutants exhibit split vacuoles. In this work, we report a novel molecular function of the BDCP SPI in ribonucleoprotein particle formation. We show that SPI interacts with the P-body core component DECAPPING PROTEIN 1 (DCP1, associates to mRNA processing bodies (P-bodies, and regulates their assembly upon salt stress. The finding that spi mutants exhibit salt hypersensitivity suggests that the local function of SPI at P-bodies is of biological relevance. Transcriptome-wide analysis revealed qualitative differences in the salt stress-regulated transcriptional response of Col-0 and spi. We show that SPI regulates the salt stress-dependent post-transcriptional stabilization, cytoplasmic agglomeration, and localization to P-bodies of a subset of salt stress-regulated mRNAs. Finally, we show that the PH-BEACH domains of SPI and its human homolog FAN (Factor Associated with Neutral sphingomyelinase activation interact with DCP1 isoforms from plants, mammals, and yeast, suggesting the evolutionary conservation of an association of BDCPs and P-bodies.

  11. Overexpression of a maize SNF-related protein kinase gene, ZmSnRK2.11, reduces salt and drought tolerance in Arabidopsis

    Institute of Scientific and Technical Information of China (English)

    ZHANG Fan; CHEN Xun-ji; WANG Jian-hua; ZHENG Jun

    2015-01-01

    Sucrose non-fermenting-1 related protein kinase 2 (SnRK2) is a unique family of protein kinases associated with abiotic stress signal transduction in plants. In this study, a maize SnRK2 gene ZmSnRK2.11 was cloned and characterized. The results showed that ZmSnRK2.11 is up-regulated by high-salinity and dehydration treatment, and it is expressed mainly in maize mature leaf. A transient expression assay using onion epidermal cel s revealed that ZmSnRK2.11-GFP fusion proteins are localized to both the nucleus and cytoplasm. Overexpressing-ZmSnRK2.11 in Arabidopsis resulted in salt and drought sensitivity phenotypes that exhibited an increased rate of water loss, reduced relative water content, delayed stoma closure, accumulated less free proline content and increased malondialdehyde (MDA) content relative to the phenotypes observed in wild-type (WT) control. Furthermore, overexpression of ZmSnRK2.11 up-regulated the expression of the genes ABI1 and ABI2 and decreased the expression of DREB2A and P5CS1. Taken together, our results suggest that ZmSnRK2.11 is a possible negative regulator involved in the salt and drought stress signal transduction pathways in plants.

  12. Generation of boron-deficiency-tolerant tomato by overexpressing an Arabidopsis thaliana borate transporter AtBOR1

    Directory of Open Access Journals (Sweden)

    Shimpei eUraguchi

    2014-04-01

    Full Text Available Nutrient deficiency in soil poses a widespread agricultural problem. Boron (B is an essential micronutrient in plants, and its deficiency causes defects in both vegetative and reproductive growth in various crops in the field. In Arabidopsis thaliana, increased expression of a major borate transporter gene AtBOR1 or boric acid channel gene AtNIP5;1 improves plant growth under B-deficient conditions. In this study, we examined whether high expression of a borate transporter gene increases B accumulation in shoots and improves the growth of tomato plant, a model of fruit-bearing crops, under B-deficient conditions. We established three independent transgenic tomato plants lines expressing AtBOR1 using Agrobacterium-mediated transformation of tomato (Solanum lycopersicum L. cv. Micro-Tom. Reverse transcription-polymerase chain reaction (RT-PCR analysis confirmed that two lines (Line 1 and Line 2 more strongly expressed AtBOR1 than Line 3. Wild-type plants and the transgenic plants were grown hydroponically under B-sufficient and B-deficient conditions. Wild-type and Line 3 (weakly expressing transgenic line showed a defect in shoot growth under B-deficient conditions, especially in the development of new leaves. However, seedlings of Line 1 and Line 2, the transgenic lines showing strong AtBOR1 expression, did not show the B-deficiency phenotype in newly developing leaves. In agreement with this phenotype, shoot biomass under low-B conditions was higher in the strongly expressing AtBOR1 line. B concentrations in leaves or fruits were also higher in Line 2 and Line 1. The present study demonstrates that strong expression of AtBOR1 improved growth in tomato under B-deficient conditions.

  13. Understanding freeze stress in biological tissues: Thermodynamics of interfacial water

    Energy Technology Data Exchange (ETDEWEB)

    Olien, C. Robert [USDA-ARS (retired), Crop and Soil Sciences, Michigan State University, East Lansing, MI 48824-1325 (United States); Livingston, David P. [USDA and North Carolina State University, Crop Science, 840 Method Road, Unit 3, Raleigh, NC 27502 (United States)]. E-mail: dpl@unity.ncsu.edu

    2006-12-01

    A thermodynamic approach to distinguish forms of freeze energy that injure plants as the temperature decreases is developed. The pattern resulting from this analysis dictated the sequence of thermal requirements for water to exist as an independent state. Improvement of freezing tolerance in biological systems depends on identification of a specific form of stress, just as control of a disease depends on identification of the pathogen causing the disease. The forms of energy that stress hydrated systems as temperature decreases begin with disruption of biological function from chill injury that occurs above freezing. Initiation of non-equilibrium freezing with sufficient free energy to drive disruptive effects can occur in a supercooled system. As the temperature continues to decrease and freezing occurs in an equilibrium manner, adhesion at hydrated interfaces contributes to disruptive effects as protoplasts contract by freeze-dehydration. If protective systems are able to prevent injury from direct interactions with ice, passive effects of freeze-dehydration may cause injury at lower temperatures. The temperature range in which an injury occurs is an indicator of the form of energy causing stress. The form of energy is thus a primary guide for selection of a protective mechanism. An interatomic force model whose response to temperature change corresponds with the enthalpy pattern might help define freeze stress from a unique perspective.

  14. Systemic low temperature signaling in Arabidopsis.

    Science.gov (United States)

    Gorsuch, Peter A; Sargeant, Alexander W; Penfield, Steven D; Quick, W Paul; Atkin, Owen K

    2010-09-01

    When leaves are exposed to low temperature, sugars accumulate and transcription factors in the C-repeat binding factor (CBF) family are expressed, which, together with CBF-independent pathways, are known to contribute to the cold acclimation process and an increase in freezing tolerance. What is not known, however, is whether expression of these cold-regulated genes can be induced systemically in response to a localized cold treatment. To address this, pre-existing, mature leaves of warm-grown Arabidopsis thaliana were exposed to a localized cold treatment (near 10 °C) whilst conjoined newly developing leaves continued only to experience warmer temperatures. In initial experiments on wild-type A. thaliana (Col-0) using real-time reverse transcription--PCR (RT-PCR) we observed that some genes--including CBF genes, certain downstream cold-responsive (COR) targets and CBF-independent transcription factors--respond to a direct 9 °C treatment of whole plants. In subsequent experiments, we found that the treatment of expanded leaves with temperatures near 10 °C can induce cold-associated genes in conjoined warm-maintained tissues. CBF1 showed a particularly strong systemic response, although CBF-independent transcription factors also responded. Moreover, the localized cold treatment of A. thaliana (C24) plants with a luciferase reporter fused to the promoter region of KIN2 indicated that in warm-maintained leaves, KIN2 might respond to a systemic signal from remote, directly cold-treated leaves. Collectively, our study provides strong evidence that the processes involved in cold acclimation are partially mediated by a signal that acts systemically. This has the potential to act as an early-warning system to enable developing leaves to cope better with the cold environment in which they are growing.

  15. Ultrasound-Assisted Freezing

    Science.gov (United States)

    Delgado, A. E.; Sun, Da-Wen

    Freezing is a well-known preservation method widely used in the food industry. The advantages of freezing are to a certain degree counterbalanced by the risk of damage caused by the formation and size of ice crystals. Over recent years new approaches have been developed to improve and control the crystallization process, and among these approaches sonocrystallization has proved to be very useful, since it can enhance both the nucleation rate and the crystal growth rate. Although ultrasound has been successfully used for many years in the evaluation of various aspects of foods and in medical applications, the use of power ultrasound to directly improve processes and products is less popular in food manufacturing. Foodstuffs are very complex materials, and research is needed in order to define the specific sound parameters that aid the freezing process and that can later be used for the scale-up and production of commercial frozen food products.

  16. Bjorken model with Freeze Out

    CERN Document Server

    Magas, V K

    2007-01-01

    The freeze out of the expanding systems, created in relativistic heavy ion collisions, is discussed. We combine Bjorken scenario with earlier developed freeze out equations into a unified model. The important feature of the proposed model is that physical freeze out is completely finished in a finite time, which can be varied from 0 (freeze out hypersurface) to infinity. The dependence of the post freeze out distribution function on this freeze out time will be studied. As an example model is completely solved and analyzed for the gas of pions.

  17. Oxime Catalysis by Freezing.

    Science.gov (United States)

    Agten, Stijn M; Suylen, Dennis P L; Hackeng, Tilman M

    2016-01-20

    Chemical reaction rates are generally decreased at lower temperatures. Here, we report that an oxime ligation reaction in water at neutral pH is accelerated by freezing. The freezing method and its rate effect on oxime ligation are systematically studied on a peptide model system, and applied to a larger chemokine protein, containing a single acetyl butyrate group, which is conjugated to an aminooxy-labeled ligand. Our improved ligation protocol now makes it possible to efficiently introduce oxime-bond coupled ligands into proteins under aqueous conditions at low concentrations and neutral pH.

  18. The cytoplasmic Cu,Zn superoxide dismutase of saccharomyces cerevisiae is required for resistance to freeze-thaw stress. Generation of free radicals during freezing and thawing

    DEFF Research Database (Denmark)

    Park, J I; Grant, C M; Davies, Michael Jonathan

    1998-01-01

    The involvement of oxidative stress in freeze-thaw injury to yeast cells was analyzed using mutants defective in a range of antioxidant functions, including Cu,Zn superoxide dismutase (encoded by SOD1), Mn superoxide dismutase (SOD2), catalase A, catalase T, glutathione reductase, gamma......-glutamylcysteine synthetase and Yap1 transcription factor. Only those affecting superoxide dismutases showed decreased freeze-thaw tolerance, with the sod1 mutant and the sod1 sod2 double mutant being most affected. This indicated that superoxide anions were formed during freezing and thawing. This was confirmed since...... the sod1 mutant could be made more resistant by treatment with the superoxide anion scavenger MnCl2, or by freezing in the absence of oxygen, or by the generation of a rho0 petite. Increased expression of SOD2 conferred freeze-thaw tolerance on the sod1 mutant indicating the ability of the mitochondrial...

  19. SLAH1, a homologue of the slow type anion channel SLAC1, modulates shoot Cl − accumulation and salt tolerance in Arabidopsis thaliana

    KAUST Repository

    Qiu, Jiaen

    2016-06-23

    Salinity tolerance is correlated with shoot chloride (Cl–) exclusion in multiple crops, but the molecular mechanisms of long-distance Cl– transport are poorly defined. Here, we characterize the in planta role of AtSLAH1 (a homologue of the slow type anion channel-associated 1 (SLAC1)). This protein, localized to the plasma membrane of root stelar cells, has its expression reduced by salt or ABA, which are key predictions for a protein involved with loading Cl– into the root xylem. Artificial microRNA knockdown mutants of AtSLAH1 had significantly reduced shoot Cl− accumulation when grown under low Cl–, whereas shoot Cl– increased and the shoot nitrate/chloride ratio decreased following AtSLAH1 constitutive or stelar-specific overexpression when grown in high Cl–. In both sets of overexpression lines a significant reduction in shoot biomass over the null segregants was observed under high Cl– supply, but not low Cl– supply. Further in planta data showed AtSLAH3 overexpression increased the shoot nitrate/chloride ratio, consistent with AtSLAH3 favouring nitrate transport. Heterologous expression of AtSLAH1 in Xenopus laevis oocytes led to no detectible transport, suggesting the need for post-translational modifications for AtSLAH1 to be active. Our in planta data are consistent with AtSLAH1 having a role in controlling root-to-shoot Cl– transport.

  20. Reference: 438 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available ity and drought tolerance in Arabidopsis thaliana. 18 6902-12 16943431 2006 Sep Molecular and cellular bio...logy Chen Zhizhong|Gong Zhizhong|Hong Xuhui|Jablonowski Daniel|Ren Xiaozhi|Schaffrath Raffael|Zhang Hairong|Zhou Xiaofeng|Zhu Jian-Kang

  1. Metabolic changes in Avena sativa crowns recovering from freezing.

    Science.gov (United States)

    Henson, Cynthia A; Duke, Stanley H; Livingston, David P

    2014-01-01

    Extensive research has been conducted on cold acclimation and freezing tolerance of fall-sown cereal plants due to their economic importance; however, little has been reported on the biochemical changes occurring over time after the freezing conditions are replaced by conditions favorable for recovery and growth such as would occur during spring. In this study, GC-MS was used to detect metabolic changes in the overwintering crown tissue of oat (Avena sativa L.) during a fourteen day time-course after freezing. Metabolomic analysis revealed increases in most amino acids, particularly proline, 5-oxoproline and arginine, which increased greatly in crowns that were frozen compared to controls and correlated very significantly with days after freezing. In contrast, sugar and sugar related metabolites were little changed by freezing, except sucrose and fructose which decreased dramatically. In frozen tissue all TCA cycle metabolites, especially citrate and malate, decreased in relation to unfrozen tissue. Alterations in some amino acid pools after freezing were similar to those observed in cold acclimation whereas most changes in sugar pools after freezing were not. These similarities and differences suggest that there are common as well as unique genetic mechanisms between these two environmental conditions that are crucial to the winter survival of plants.

  2. Metabolic changes in Avena sativa crowns recovering from freezing.

    Directory of Open Access Journals (Sweden)

    Cynthia A Henson

    Full Text Available Extensive research has been conducted on cold acclimation and freezing tolerance of fall-sown cereal plants due to their economic importance; however, little has been reported on the biochemical changes occurring over time after the freezing conditions are replaced by conditions favorable for recovery and growth such as would occur during spring. In this study, GC-MS was used to detect metabolic changes in the overwintering crown tissue of oat (Avena sativa L. during a fourteen day time-course after freezing. Metabolomic analysis revealed increases in most amino acids, particularly proline, 5-oxoproline and arginine, which increased greatly in crowns that were frozen compared to controls and correlated very significantly with days after freezing. In contrast, sugar and sugar related metabolites were little changed by freezing, except sucrose and fructose which decreased dramatically. In frozen tissue all TCA cycle metabolites, especially citrate and malate, decreased in relation to unfrozen tissue. Alterations in some amino acid pools after freezing were similar to those observed in cold acclimation whereas most changes in sugar pools after freezing were not. These similarities and differences suggest that there are common as well as unique genetic mechanisms between these two environmental conditions that are crucial to the winter survival of plants.

  3. Identification of Mild Freezing Shock Response Pathways in Barley Based on Transcriptome Profiling.

    Science.gov (United States)

    Wang, Xiaolei; Wu, Dezhi; Yang, Qian; Zeng, Jianbin; Jin, Gulei; Chen, Zhong-Hua; Zhang, Guoping; Dai, Fei

    2016-01-01

    Low temperature is a major abiotic stress affecting crop growth and productivity. A better understanding of low temperature tolerance mechanisms is imperative for developing the crop cultivars with improved tolerance. We herein performed an Illumina RNA-sequencing experiment using two barley genotypes differing in freezing tolerance (Nure, tolerant and Tremois, sensitive), to determine the transcriptome profiling and genotypic difference under mild freezing shock treatment after a very short acclimation for gene induction. A total of 6474 differentially expressed genes, almost evenly distributed on the seven chromosomes, were identified. The key DEGs could be classified into six signaling pathways, i.e., Ca(2+) signaling, PtdOH signaling, CBFs pathway, ABA pathway, jasmonate pathway, and amylohydrolysis pathway. Expression values of DEGs in multiple signaling pathways were analyzed and a hypothetical model of mild freezing shock tolerance mechanism was proposed. Expression and sequence profile of HvCBFs cluster within Frost resistance-H2, a major quantitative trait locus on 5H being closely related to low temperature tolerance in barley, were further illustrated, considering the crucial role of HvCBFs on freezing tolerance. It may be concluded that multiple signaling pathways are activated in concert when barley is exposed to mild freezing shock. The pathway network we presented may provide a platform for further exploring the functions of genes involved in low temperature tolerance in barley.

  4. Soybean NAC transcription factors promote abiotic stress tolerance and lateral root formation in transgenic plants.

    Science.gov (United States)

    Hao, Yu-Jun; Wei, Wei; Song, Qing-Xin; Chen, Hao-Wei; Zhang, Yu-Qin; Wang, Fang; Zou, Hong-Feng; Lei, Gang; Tian, Ai-Guo; Zhang, Wan-Ke; Ma, Biao; Zhang, Jin-Song; Chen, Shou-Yi

    2011-10-01

    NAC transcription factors play important roles in plant growth, development and stress responses. Previously, we identified multiple NAC genes in soybean (Glycine max). Here, we identify the roles of two genes, GmNAC11 and GmNAC20, in stress responses and other processes. The two genes were differentially induced by multiple abiotic stresses and plant hormones, and their transcripts were abundant in roots and cotyledons. Both genes encoded proteins that localized to the nucleus and bound to the core DNA sequence CGT[G/A]. In the protoplast assay system, GmNAC11 acts as a transcriptional activator, whereas GmNAC20 functions as a mild repressor; however, the C-terminal end of GmANC20 has transcriptional activation activity. Over-expression of GmNAC20 enhances salt and freezing tolerance in transgenic Arabidopsis plants; however, GmNAC11 over-expression only improves salt tolerance. Over-expression of GmNAC20 also promotes lateral root formation. GmNAC20 may regulate stress tolerance through activation of the DREB/CBF-COR pathway, and may control lateral root development by altering auxin signaling-related genes. GmNAC11 probably regulates DREB1A and other stress-related genes. The roles of the two GmNAC genes in stress tolerance were further analyzed in soybean transgenic hairy roots. These results provide a basis for genetic manipulation to improve the agronomic traits of important crops.

  5. Freezing increment in keratophakia.

    Science.gov (United States)

    Swinger, C A; Wisnicki, H J

    In homoplastic keratomileusis, keratophakia, and epikeratophakia, the corneal tissue that provides the final refractive lenticule undergoes a conformational change when frozen. Because corneal tissue is composed primarily of water, an assumed value of 9.08% (approximate volumic percentage expansion of water when frozen) is frequently used for the increase in thickness, or freezing increment, rather than measuring it directly. We evaluated 32 cases of clinical keratophakia and found the increase in thickness to average 37 +/- 21%. In this series of 32 cases, the percentage of patients with a greater than 4 D residual refractive error was 16%. If an assumed freezing increment of 9.08% had been used, the percentage would have been 28%, with two-thirds of these 28% manifesting a marked undercorrection. Because of a lack of studies documenting the behavior of corneal tissue following cryoprotection and freezing, it is suggested that measurements be taken during homoplastic surgery to minimize the potential for significant inaccuracy in obtaining the desired optic result.

  6. Comparative metabolic profiling of Haberlea rhodopensis, Thellungiella halophyla, and Arabidopsis thaliana exposed to low temperature

    Directory of Open Access Journals (Sweden)

    Maria eBenina

    2013-12-01

    Full Text Available Haberlea rhodopensis is a resurrection species with extreme resistance to drought stress and desiccation but also with ability to withstand low temperatures and freezing stress. In order to identify biochemical strategies which contribute to Haberlea’s remarkable stress tolerance, the metabolic reconfiguration of H. rhodopensis during low temperature (4°C and subsequent return to optimal temperatures was investigated and compared with that of the stress tolerant Thellungiella halophyla and the stress sensitive A. thaliana. The effect of the low temperature treatment in the three species was confirmed by gene expression of low-temperature- and dehydration-inducible genes. Metabolic analysis by GC-MS revealed intrinsic differences in the metabolite levels of the three species even at 21°C. H. rhodopensis had significantly more raffinose, melibiose, trehalose, myo-inositol, sorbitol, and galactinol than the other two species. A. thaliana had the highest levels of putrescine and fumarate, while T. halophila had much higher levels of several amino acids, including alanine, asparagine, beta-alanine, histidine, isoleucine, phenylalanine, serine, threonine, and valine. In addition, the three species responded differently to the low temperature treatment and the subsequent recovery, especially with regard to the sugar metabolism. Chilling induced accumulation of maltose in Haberlea and raffinose in A. thaliana, but raffinose levels in low temperature exposed Arabidopsis were still much lower than these in unstressed Haberlea. While all species accumulated sucrose during chilling, that accumulation was transient in Haberlea and Arabidopsis but sustained in T. halophila after the return to optimal temperature. In T. halophila, the levels of proline and hydroxyproline drastically increased upon recovery. Collectively, these results show inherent. differences in the metabolomes under the ambient temperature and the strategies to respond to low

  7. Differential freezing resistance and photoprotection in C3 and C4 eudicots and grasses.

    Science.gov (United States)

    Liu, Mei-Zhen; Osborne, Colin P

    2013-05-01

    Globally, C4 plants dominate hot, open environments, but this general pattern is underpinned by important differences in the biogeography of C4 lineages. In particular, the species richness of C4 Poaceae (grasses) increases strongly with increasing temperature, whereas that of the major C4 eudicot group Chenopodiaceae correlates positively with aridity. Freezing tolerance is a crucial determinant of biogeographical relationships with temperature and is mediated by photodamage and cellular disruption by desiccation, but little is known about differences between C4 families. This study hypothesized that there is a greater risk of freezing damage via these mechanisms in C4 Poaceae than Chenopodiaceae, that freezing protection differs between the taxonomic groups, and that freezing tolerance of species is linked to arid habitat preference. Chlorophyll fluorescence, water relations, and freezing injury were compared in four C3 and six C4 species of Poaceae and Chenopodiaceae from the same Mongolian flora. Contrary to expectations, freezing-induced leaf mortality and photodamage were lower in Poaceae than Chenopodiaceae species, and unrelated to photosynthetic pathway. The freezing resistance of Poaceae species resulted from constitutive protection and cold acclimation and an ability to protect the photosynthetic apparatus from photodamage. Freezing protection was associated with low osmotic potential and low tissue elasticity, and freezing damage was accompanied by electrolyte leakage, consistent with cell-membrane disruption by ice. Both Chenopodiaceae and Poaceae had the potential to develop cold acclimation and withstand freezing during the growing season, which conflicted with the hypothesis. Instead, freezing tolerance was more closely associated with life history and ecological preference in these Mongolian species.

  8. Biomaterials by freeze casting.

    Science.gov (United States)

    Wegst, Ulrike G K; Schecter, Matthew; Donius, Amalie E; Hunger, Philipp M

    2010-04-28

    The functional requirements for synthetic tissue substitutes appear deceptively simple: they should provide a porous matrix with interconnecting porosity and surface properties that promote rapid tissue ingrowth; at the same time, they should possess sufficient stiffness, strength and toughness to prevent crushing under physiological loads until full integration and healing are reached. Despite extensive efforts and first encouraging results, current biomaterials for tissue regeneration tend to suffer common limitations: insufficient tissue-material interaction and an inherent lack of strength and toughness associated with porosity. The challenge persists to synthesize materials that mimic both structure and mechanical performance of the natural tissue and permit strong tissue-implant interfaces to be formed. In the case of bone substitute materials, for example, the goal is to engineer high-performance composites with effective properties that, similar to natural mineralized tissue, exceed by orders of magnitude the properties of its constituents. It is still difficult with current technology to emulate in synthetic biomaterials multi-level hierarchical composite structures that are thought to be the origin of the observed mechanical property amplification in biological materials. Freeze casting permits to manufacture such complex, hybrid materials through excellent control of structural and mechanical properties. As a processing technique for the manufacture of biomaterials, freeze casting therefore has great promise.

  9. Performance Characteristics of an Isothermal Freeze Valve

    Energy Technology Data Exchange (ETDEWEB)

    Hailey, A.E.

    2001-08-22

    This document discusses performance characteristics of an isothermal freeze valve. A freeze valve has been specified for draining the DWPF melter at the end of its lifetime. Two freeze valve designs have been evaluated on the Small Cylindrical Melter-2 (SCM-2). In order to size the DWPF freeze valve, the basic principles governing freeze valve behavior need to be identified and understood.

  10. Surviving freezing in plant tissues by oomycetous snow molds.

    Science.gov (United States)

    Murakami, Ryo; Yajima, Yuka; Kida, Ken-ichi; Tokura, Katsuyuki; Tojo, Motoaki; Hoshino, Tamotsu

    2015-04-01

    Oomyceteous snow molds, Pythium species, were reported to be less tolerant to chilling and freezing temperatures than other snow mold taxa. However, Pythium species are often found to be pathogenic on mosses in Polar Regions. We investigated the frost resistance of Pythium species from Temperate (Hokkaido, Japan) and Subantarctic Regions. Free mycelia and hyphal swellings, structures for survival, of Pythium iwayamai and Pythium paddicum lost viability within freeze-thaw 3 cycles; however, mycelia in host plants survived the treatment. It was reported that fungi in permafrost are characterized both by the presence of natural cryoprotectants in these ecotopes and by the ability to utilize their inherent mechanisms of protection. It is conceivable that plant substrates or derivatives thereof are natural cryoprotectants, enabling them to provide advantageous conditions to microorganisms under freezing conditions. Our results are the first to experimentally support this hypothesis.

  11. Tolerating Zero Tolerance?

    Science.gov (United States)

    Moore, Brian N.

    2010-01-01

    The concept of zero tolerance dates back to the mid-1990s when New Jersey was creating laws to address nuisance crimes in communities. The main goal of these neighborhood crime policies was to have zero tolerance for petty crime such as graffiti or littering so as to keep more serious crimes from occurring. Next came the war on drugs. In federal…

  12. Understanding Slag Freeze Linings

    Science.gov (United States)

    Fallah-Mehrjardi, Ata; Hayes, Peter C.; Jak, Evgueni

    2014-09-01

    Slag freeze linings, the formation of protective deposit layers on the inner walls of furnaces and reactors, are increasingly used in industrial pyrometallurgical processes to ensure that furnace integrity is maintained in these aggressive, high-temperature environments. Most previous studies of freeze-linings have analyzed the formation of slag deposits based solely on heat transfer considerations. These thermal models have assumed that the interface between the stationary frozen layer and the agitated molten bath at steady-state deposit thickness consists of the primary phase, which stays in contact with the bulk liquid at the liquidus temperature. Recent experimental studies, however, have clearly demonstrated that the temperature of the deposit/liquid bath interface can be lower than the liquidus temperature of the bulk liquid. A conceptual framework has been proposed to explain the observations and the factors influencing the microstructure and the temperature of the interface at steady-state conditions. The observations are consistent with a dynamic steady state that is a balance between (I) the rate of nucleation and growth of solids on detached crystals in a subliquidus layer as this fluid material moves toward the stagnant deposit interface and (II) the dissolution of these detached crystals as they are transported away from the interface by turbulent eddies. It is argued that the assumption that the interface temperature is the liquidus of the bulk material represents only a limiting condition, and that the interface temperature can be between T liquidus and T solidus depending on the process conditions and bath chemistry. These findings have implications for the modeling approach and boundary conditions required to accurately describe these systems. They also indicate the opportunity to integrate considerations of heat and mass flows with the selection of melt chemistries in the design of future high temperature industrial reactors.

  13. Reference: 34 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available al gene in different tissues, under normal growth conditions, and when the plants were subjected to anoxia or other environmental...e1 gene of Arabidopsis is required during anoxia but not other environmental stre...ronmental stresses. We also characterize the expression of the aldehyde dehydrogena...ed under oxygen limitation among the PDC1 gene family and that a pdc1 null mutant is comprised in anoxia tolerance but not other envi

  14. A Nucleocytoplasmic Shuttling Protein in Oxidative Stress Tolerance

    Energy Technology Data Exchange (ETDEWEB)

    Ow, David W.; Song, Wen

    2003-03-26

    Plants for effective extraction of toxic metals and radionuclides must tolerate oxidative stress. To identify genes that enhance oxidative stress tolerance, an S. pombe cDNA expression plasmid library was screened for the ability to yield hypertolerant colonies. Here, we report on the properties of one gene that confers hypertolerance to cadmium and oxidizing chemicals. This gene appears to be conserved in other organisms as homologous genes are found in human, mouse, fruitfly and Arabidopsis. The fruitfly and Arabidopsis genes likewise enhance oxidative stress tolerance in fission yeast. During oxidative stress, the amount of mRNA does not change, but protein fusions to GFP relocate from the cytoplasm to the nucleus. The same pattern is observed with the Arabidopsis homologue-GFP fusion protein. This behavior suggests a signaling role in oxidative stress tolerance and these conserved proteins may be targets for engineering stress tolerant plants for phytoremediation.

  15. Genome-Wide Investigation of MicroRNAs and Their Targets in Response to Freezing Stress in Medicago sativa L., Based on High-Throughput Sequencing.

    Science.gov (United States)

    Shu, Yongjun; Liu, Ying; Li, Wei; Song, Lili; Zhang, Jun; Guo, Changhong

    2016-01-22

    Winter damage, especially in northern climates, is a major limitation of the utilization of perennial forages such as alfalfa. Therefore, improving freezing tolerance is imperative in alfalfa genetic breeding. However, freezing tolerance is a complex trait that is determined by many genes. To understand the complex regulation mechanisms of freezing tolerance in alfalfa, we performed small RNA sequencing analysis under cold (4°) and freezing (-8°) stress. The sequencing results revealed that 173 known, and 24 novel miRNAs were expressed, and that the expression of 35 miRNAs was affected by cold and/or freezing stress. Meanwhile, 105 target genes cleaved by these miRNAs were characterized by degradome sequencing. These targets were associated with biological regulation, cellular processes, metabolic processes, and response to stress. Interestingly, most of them were characterized as transcription factors (TFs), including auxin response factors, SBP, NAC, AP2/ERF, and GRF, which play important roles in plant abiotic responses. In addition, important miRNAs and mRNAs involved in nodulation were also identified, for example, the relationship between miR169 and the TF CCAAT (also named as NF-YA/HAP2), which suggested that nodulation has an important function in freezing tolerance in alfalfa. Our results provide valuable information to help determine the molecular mechanisms of freezing tolerance in alfalfa, which will aid the application of these miRNAs and their targets in the improvement of freezing tolerance in alfalfa and related plants.

  16. Genome-Wide Investigation of MicroRNAs and Their Targets in Response to Freezing Stress in Medicago sativa L., Based on High-Throughput Sequencing

    Directory of Open Access Journals (Sweden)

    Yongjun Shu

    2016-03-01

    Full Text Available Winter damage, especially in northern climates, is a major limitation of the utilization of perennial forages such as alfalfa. Therefore, improving freezing tolerance is imperative in alfalfa genetic breeding. However, freezing tolerance is a complex trait that is determined by many genes. To understand the complex regulation mechanisms of freezing tolerance in alfalfa, we performed small RNA sequencing analysis under cold (4° and freezing (−8° stress. The sequencing results revealed that 173 known, and 24 novel miRNAs were expressed, and that the expression of 35 miRNAs was affected by cold and/or freezing stress. Meanwhile, 105 target genes cleaved by these miRNAs were characterized by degradome sequencing. These targets were associated with biological regulation, cellular processes, metabolic processes, and response to stress. Interestingly, most of them were characterized as transcription factors (TFs, including auxin response factors, SBP, NAC, AP2/ERF, and GRF, which play important roles in plant abiotic responses. In addition, important miRNAs and mRNAs involved in nodulation were also identified, for example, the relationship between miR169 and the TF CCAAT (also named as NF-YA/HAP2, which suggested that nodulation has an important function in freezing tolerance in alfalfa. Our results provide valuable information to help determine the molecular mechanisms of freezing tolerance in alfalfa, which will aid the application of these miRNAs and their targets in the improvement of freezing tolerance in alfalfa and related plants.

  17. Genome-Wide Investigation of MicroRNAs and Their Targets in Response to Freezing Stress in Medicago sativa L., Based on High-Throughput Sequencing

    Science.gov (United States)

    Shu, Yongjun; Liu, Ying; Li, Wei; Song, Lili; Zhang, Jun; Guo, Changhong

    2016-01-01

    Winter damage, especially in northern climates, is a major limitation of the utilization of perennial forages such as alfalfa. Therefore, improving freezing tolerance is imperative in alfalfa genetic breeding. However, freezing tolerance is a complex trait that is determined by many genes. To understand the complex regulation mechanisms of freezing tolerance in alfalfa, we performed small RNA sequencing analysis under cold (4°) and freezing (−8°) stress. The sequencing results revealed that 173 known, and 24 novel miRNAs were expressed, and that the expression of 35 miRNAs was affected by cold and/or freezing stress. Meanwhile, 105 target genes cleaved by these miRNAs were characterized by degradome sequencing. These targets were associated with biological regulation, cellular processes, metabolic processes, and response to stress. Interestingly, most of them were characterized as transcription factors (TFs), including auxin response factors, SBP, NAC, AP2/ERF, and GRF, which play important roles in plant abiotic responses. In addition, important miRNAs and mRNAs involved in nodulation were also identified, for example, the relationship between miR169 and the TF CCAAT (also named as NF-YA/HAP2), which suggested that nodulation has an important function in freezing tolerance in alfalfa. Our results provide valuable information to help determine the molecular mechanisms of freezing tolerance in alfalfa, which will aid the application of these miRNAs and their targets in the improvement of freezing tolerance in alfalfa and related plants. PMID:26801649

  18. OsLEA3-2, an abiotic stress induced gene of rice plays a key role in salt and drought tolerance.

    Directory of Open Access Journals (Sweden)

    Jianli Duan

    Full Text Available Late embryogenesis abundant (LEA proteins are involved in tolerance to drought, cold and high salinity in many different organisms. In this report, a LEA protein producing full-length gene OsLEA3-2 was identified in rice (Oryza sativa using the Rapid Amplification of cDNA Ends (RACE method. OsLEA3-2 was found to be only expressed in the embryo and can be induced by abiotic stresses. The coding protein localizes to the nucleus and overexpression of OsLEA3-2 in yeast improved growth performance compared with control under salt- and osmotic-stress conditions. OsLEA3-2 was also inserted into pHB vector and overexpressed in Arabidopsis and rice. The transgenic Arabidopsis seedlings showed better growth on MS media supplemented with 150 mM mannitol or 100 mM NaCl as compared with wild type plants. The transgenic rice also showed significantly stronger growth performance than control under salinity or osmotic stress conditions and were able to recover after 20 days of drought stress. In vitro analysis showed that OsLEA3-2 was able to protect LDH from aggregation on freezing and inactivation on desiccation. These results indicated that OsLEA3-2 plays an important role in tolerance to abiotic stresses.

  19. 9 CFR 590.534 - Freezing facilities.

    Science.gov (United States)

    2010-01-01

    ... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Freezing facilities. 590.534 Section..., and Facility Requirements § 590.534 Freezing facilities. (a) Freezing rooms, either on or off the... as set forth in § 590.536. Use of off-premise freezing facilities is permitted only when...

  20. Comparison of cell components in low sugar adaptation and freeze-tolerance baker's yeast with common yeast%低糖适应性耐冻酵母菌与普通酵母菌细胞构成成分的比较

    Institute of Scientific and Technical Information of China (English)

    宋振玉; 李楠; 张姝; 王雷; 居勇

    2009-01-01

    采用气相、液相色谱法和分光光度比色法,对筛选出的低糖适应性耐冻面包酵母BY-03和FY-03与普通高糖面包酵母(PT)细胞构成成分,即胞内海藻糖含量,脂肪酸组成,麦角固醇,磷脂和氨基酸组成进行了分析与比较,进而了解其对酵母耐冻性的影响.结果表明,FY-03海藻糖含量是PT含量的1.40倍,BY-03的海藻糖含量与PT含量基本持平.从3种酵母中皆检出18种氨基酸,其中有助于提高酵母耐冻性的3种带电荷氨基酸即精氨酸,脯氨酸和谷氨酸的含量,BY-03和FY-03均高于PT.从3种酵母中检出了8种饱和与不饱和的脂肪酸,其中BY-03、FY-03的不饱和脂肪酸比例分别为79.82%和78.62%,明显高于PT 64.96%,其中棕榈油酸C16∶ 1和油酸C18∶ 1的含量相差较大.麦角固醇的含量BY-03和FY-03分别为4.99mg/g和4.77mg/g显著高于PT的2.56mg/g,而三者的磷脂含量没有明显差别.%The cell components, including trehalose, fatty acid component, ergosterol, phospholipid and amino acid in the BY-03 and FY-03 were qualitatively and quantitatively determined and compared with the common baker's yeast (PT) by GC, HPLC and UV-spectrophotometer in order to find out the effects of these index on freeze-tolerance of yeast.The results suggest that the content of the trehalose in FY-03 was 1.4 times more than that in PT, while the one in BY-03 was similar to PT.Meanwhile, eighteen kinds of known amino acid were detected from three kinds of yeast.The content of the arginine, proline and glutamate, which were helpful for enhancing the ability of freeze-tolerance, in BY-03 and FY-03 were more than those in PT.Eight kinds of known saturated and unsaturated fatty acid components were detected in three kinds of yeasts. The unsaturated fatty acid in BY-03 and FY-03 were 79.82% and 78.62%, 4.99 mg/g and 4.77 mg/g, but 2.57 mg/g in PT, while the phospholipid contents were similar in all samples.

  1. Arabidopsis hybrid speciation processes.

    Science.gov (United States)

    Schmickl, Roswitha; Koch, Marcus A

    2011-08-23

    The genus Arabidopsis provides a unique opportunity to study fundamental biological questions in plant sciences using the diploid model species Arabidopsis thaliana and Arabidopsis lyrata. However, only a few studies have focused on introgression and hybrid speciation in Arabidopsis, although polyploidy is a common phenomenon within this genus. More recently, there is growing evidence of significant gene flow between the various Arabidopsis species. So far, we know Arabidopsis suecica and Arabidopsis kamchatica as fully stabilized allopolyploid species. Both species evolved during Pleistocene glaciation and deglaciation cycles in Fennoscandinavia and the amphi-Beringian region, respectively. These hybrid studies were conducted either on a phylogeographic scale or reconstructed experimentally in the laboratory. In our study we focus at a regional and population level. Our research area is located in the foothills of the eastern Austrian Alps, where two Arabidopsis species, Arabidopsis arenosa and A. lyrata ssp. petraea, are sympatrically distributed. Our hypothesis of genetic introgression, migration, and adaptation to the changing environment during the Pleistocene has been confirmed: We observed significant, mainly unidirectional gene flow between the two species, which has given rise to the tetraploid A. lyrata. This cytotype was able to escape from the narrow ecological niche occupied by diploid A. lyrata ssp. petraea on limestone outcrops by migrating northward into siliceous areas, leaving behind a trail of genetic differentiation.

  2. Reciprocal transplants demonstrate strong adaptive differentiation of the model organism Arabidopsis thaliana in its native range.

    Science.gov (United States)

    Agren, Jon; Schemske, Douglas W

    2012-06-01

    To quantify adaptive differentiation in the model plant Arabidopsis thaliana, we conducted reciprocal transplant experiments for five years between two European populations, one near the northern edge of the native range (Sweden) and one near the southern edge (Italy). We planted seeds (years 1-3) and seedlings (years 4-5), and estimated fitness as the number of fruits produced per seed or seedling planted. In eight of the 10 possible site × year comparisons, the fitness of the local population was significantly higher than that of the nonlocal population (3.1-22.2 times higher at the southern site, and 1.7-3.6 times higher at the northern site); in the remaining two comparisons no significant difference was recorded. At both sites, the local genotype had higher survival than the nonlocal genotype, and at the Italian site, the local genotype also had higher fecundity. Across years, the relative survival of the Italian genotype at the northern site decreased with decreasing winter soil temperature. The results provide evidence of strong adaptive differentiation between natural populations of A. thaliana and indicate that differences in tolerance to freezing contributed to fitness variation at the northern site. In ongoing work, we explore the functional and genetic basis of this adaptive differentiation.

  3. Fundamentals of freeze-drying.

    Science.gov (United States)

    Nail, Steven L; Jiang, Shan; Chongprasert, Suchart; Knopp, Shawn A

    2002-01-01

    Given the increasing importance of reducing development time for new pharmaceutical products, formulation and process development scientists must continually look for ways to "work smarter, not harder." Within the product development arena, this means reducing the amount of trial and error empiricism in arriving at a formulation and identification of processing conditions which will result in a quality final dosage form. Characterization of the freezing behavior of the intended formulation is necessary for developing processing conditions which will result in the shortest drying time while maintaining all critical quality attributes of the freeze-dried product. Analysis of frozen systems was discussed in detail, particularly with respect to the glass transition as the physical event underlying collapse during freeze-drying, eutectic mixture formation, and crystallization events upon warming of frozen systems. Experiments to determine how freezing and freeze-drying behavior is affected by changes in the composition of the formulation are often useful in establishing the "robustness" of a formulation. It is not uncommon for seemingly subtle changes in composition of the formulation, such as a change in formulation pH, buffer salt, drug concentration, or an additional excipient, to result in striking differences in freezing and freeze-drying behavior. With regard to selecting a formulation, it is wise to keep the formulation as simple as possible. If a buffer is needed, a minimum concentration should be used. The same principle applies to added salts: If used at all, the concentration should be kept to a minimum. For many proteins a combination of an amorphous excipient, such as a disaccharide, and a crystallizing excipient, such as glycine, will result in a suitable combination of chemical stability and physical stability of the freeze-dried solid. Concepts of heat and mass transfer are valuable in rational design of processing conditions. Heat transfer by conduction

  4. Freezing in a vertical tube

    Energy Technology Data Exchange (ETDEWEB)

    Sparrow, E.M.; Broadbent, J.A.

    1983-05-01

    Fundamental heat transfer experiments were performed for freezing of an initially superheated or nonsuperheated liquid in a cooled vertical tube. Measurements were made which yielded information about the freezing front and the frozen mass, about the various energy components extracted from the tube, and about the decay of the initial liquid superheat. Four component energies were identified and evaluated from the experimental data, including the latent energy released by the phase change and sensibly energies released from the subcooled frozen solid and the superheated liquid. Initial superheating of the liquid tended to moderately diminish the frozen mass and latent energy extraction at short freezing times but had little effect on these quantitites at longer times. The extracted sensible energies associated with the superheating more than compensated for the aforementioned decrease in the latent energy. Although the latent energy is the largest contributor to the total extracted energy, the aggregate sensible energies can make a significant contribution, especially at large tube wall subcooling, large initial liquid superheating, and short freezing time. Natural convection effects in the superheated liquid were modest and were confined to short freezing times.

  5. Antifreeze proteins enable plants to survive in freezing conditions

    Indian Academy of Sciences (India)

    Ravi Gupta; Renu Deswal

    2014-12-01

    Overwintering plants secrete antifreeze proteins (AFPs) to provide freezing tolerance. These proteins bind to and inhibit the growth of ice crystals that are formed in the apoplast during subzero temperatures. Antifreeze activity has been detected in more than 60 plants and AFPs have been purified from 15 of these, including gymnosperms, dicots and monocots. Biochemical characterization of plant antifreeze activity, as determined by the high ice recrystallization inhibition (IRI) activities and low thermal hysteresis (TH) of AFPs, showed that their main function is inhibition of ice crystal growth rather than the lowering of freezing temperatures. However, recent studies showed that antifreeze activity with higher TH also exists in plants. Calcium and hormones like ethylene and jasmonic acid have been shown to regulate plant antifreeze activity. Recent studies have shown that plant AFPs bind to both prism planes and basal planes of ice crystals by means of two flat ice binding sites. Plant AFPs have been postulated to evolve from the OsLRR-PSR gene nearly 36 million years ago. In this review, we present the current scenario of plant AFP research in order to understand the possible potential of plant AFPs in generation of freezing-tolerant crops.

  6. Freeze-in through portals

    CERN Document Server

    Blennow, Mattias; Zaldivar, Bryan

    2014-01-01

    The popular freeze-out paradigm for Dark Matter (DM) production, relies on DM-baryon couplings of the order of the weak interactions. However, different search strategies for DM have failed to provide a conclusive evidence of such (non-gravitational) interactions, while greatly reducing the parameter space of many representative models. This motivates the study of alternative mechanisms for DM genesis. In the freeze-in framework, the DM is slowly populated from the thermal bath while never reaching equilibrium. In this work, we analyse in detail the possibility of producing a frozen-in DM via a mediator particle which acts as a portal. We give analytical estimates of different freeze-in regimes and support them with full numerical analyses, taking into account the proper distribution functions of bath particles. Finally, we constrain the parameter space of generic models by requiring agreement with DM relic abundance observations.

  7. Basic concepts in freezing cells

    Energy Technology Data Exchange (ETDEWEB)

    Mazur, P.

    1985-01-01

    Freezing involves the lowering of temperature and the formation of ice. Most cells have not been found to be sensitive to the former; rather injury is a consequence of the removal of water from the system in the form of ice. Some cells such as boar sperm and those of many tropical crops are susceptible to even short-term lowering of temperature to near O/sup 0/C. This susceptiblity, which is independent of the rate of temperature drop, is defined as chilling injury. Other cells are injured by chilling only if the rate of cooling is high, a phenomenon referred to as thermal shock. This paper discusses the physical-chemical events during freezing and on freezing injury will assume that lowered temperature per se is not injurious.

  8. Freeze Protection in Gas Holders

    DEFF Research Database (Denmark)

    Hjorth, Poul G.; Duursma, Gail

    In cold weather, the water seals of gasholders need protection from freez- ing to avoid compromising the seal. These holders have a large reservoir of “tank water” at the base which is below ground. At present freeze- protection is achieved by external heating of the seal water which...... is in a slotted channel called a cup. Electrical heating or circulation of heated tank water to the cup are examples of systems presently used. The tank water has a large thermal capacity and National Grid wishes to inves- tigate whether circulation of the tank water without external heating could provide...... sufficient energy input to avoid freezing. Only tanks in which the tank water is below ground are investigated in the report. The soil temperature under the reservoir at depth of 10m and lower is almost constant....

  9. Isolation and characterization of the Arabidopsis heat-intolerant 2 (hit2) mutant reveal the essential role of the nuclear export receptor EXPORTIN1A (XPO1A) in plant heat tolerance.

    Science.gov (United States)

    Wu, Shin-Jye; Wang, Lian-Chin; Yeh, Ching-Hui; Lu, Chun-An; Wu, Shaw-Jye

    2010-06-01

    *The Arabidopsis heat-intolerant 2 (hit2) mutant was isolated on the basis of its impaired ability to withstand moderate heat stress (37 degrees C). Determination of the genetic mutation that underlies the hit2 thermosensitive phenotype allowed better understanding of the mechanisms by which plants cope with heat stress. *Genetic analysis revealed that hit2 is a single recessive mutation. Map-based cloning was used to identify the hit2 locus. The response of hit2 to other types of heat stress was also investigated to characterize the protective role of HIT2. *hit2 was defective in basal but not in acquired thermotolerance. hit2 was sensitive to methyl viologen-induced oxidative stress, and the survival of hit2 seedlings in response to heat stress was affected by light conditions. The mutated locus was located at the EXPORTIN1A (XPO1A) gene, which encodes a nuclear transport receptor. Two T-DNA insertion lines, xpo1a-1 and xpo1a-3, exhibited the same phenotypes as hit2. *The results provide evidence that Arabidopsis XPO1A is dispensable for normal plant growth and development but is essential for thermotolerance, in part by mediating the protection of plants against heat-induced oxidative stress.

  10. Meat Freezing Theories and Novel Freezing Technologies%肉类冷冻理论与冷冻新技术

    Institute of Scientific and Technical Information of China (English)

    金文刚

    2008-01-01

    Main meat freezing theories,including transition theory,glass transformation theory and ice crystallization theory,were introduced.Some novel freezing technologies such as high pressure freezing,ultrasonic freezing,ice nucleus bacteria freezing protein,cell alive system freezing and decompression freezing were also generally reviewed.

  11. Facing Freeze: Social Threat Induces Bodily Freeze in Humans

    NARCIS (Netherlands)

    Roelofs, K.; Hagenaars, M.A.; Stins, J.F.

    2010-01-01

    Freezing is a common defensive response in animals threatened by predators. It is characterized by reduced body motion and decreased heart rate (bradycardia). However, despite the relevance of animal defense models in human stress research, studies have not shown whether social threat cues elicit si

  12. Medical and social egg freezing

    DEFF Research Database (Denmark)

    Lallemant, Camille; Vassard, Ditte; Andersen, Anders Nyboe

    2016-01-01

    was collected from September 2012 to September 2013 and the responses of 973 women were analyzed. In total, 83% of women reported having heard of egg freezing, and nearly all considered it acceptable for medical indications, whilst 89% considered it acceptable for social reasons. Overall, 19% expressed active...

  13. Time dependence of immersion freezing

    Directory of Open Access Journals (Sweden)

    A. Welti

    2012-05-01

    Full Text Available The time dependence of immersion freezing was studied for temperatures between 236 K and 243 K. Droplets with single immersed, size-selected 400 nm and 800 nm kaolinite particles were produced at 300 K, cooled down to supercooled temperatures typical for mixed-phase cloud conditions, and the fraction of frozen droplets with increasing residence time was detected. To simulate the conditions of immersion freezing in mixed-phase clouds we used the Zurich Ice Nucleation Chamber (ZINC and its vertical extension, the Immersion Mode Cooling chAmber (IMCA. We observed that the frozen fraction of droplets increased with increasing residence time in the chamber. This suggests that there is a time dependence of immersion freezing and supports the importance of a stochastic component in the ice nucleation process. The rate at which droplets freeze was observed to decrease towards higher temperatures and smaller particle sizes. Comparison of the laboratory data with four different ice nucleation models, three based on classical nucleation theory with different representations of the particle surface properties and one singular, suggest that the classical, stochastic approach combined with a distribution of contact angles is able to reproduce the ice nucleation observed in these experiments most accurately. Using the models to calculate the increase in frozen fraction at typical mixed-phase cloud temperatures over an extended period of time, yields an equivalent effect of −1 K temperature shift and an increase in time scale by a factor of ~10.

  14. Deep-sequencing transcriptome analysis of field-grown Medicago sativa L. crown buds acclimated to freezing stress.

    Science.gov (United States)

    Song, Lili; Jiang, Lin; Chen, Yue; Shu, Yongjun; Bai, Yan; Guo, Changhong

    2016-09-01

    Medicago sativa L. (alfalfa) 'Zhaodong' is an important forage legume that can safely survive in northern China where winter temperatures reach as low as -30 °C. Survival of alfalfa following freezing stress depends on the amount and revival ability of crown buds. In order to investigate the molecular mechanisms of frost tolerance in alfalfa, we used transcriptome sequencing technology and bioinformatics strategies to analyze crown buds of field-grown alfalfa during winter. We statistically identified a total of 5605 differentially expressed genes (DEGs) involved in freezing stress including 1900 upregulated and 3705 downregulated DEGs. We validated 36 candidate DEGs using qPCR to confirm the accuracy of the RNA-seq data. Unlike other recent studies, this study employed alfalfa plants grown in the natural environment. Our results indicate that not only the CBF orthologs but also membrane proteins, hormone signal transduction pathways, and ubiquitin-mediated proteolysis pathways indicate the presence of a special freezing adaptation mechanism in alfalfa. The antioxidant defense system may rapidly confer freezing tolerance to alfalfa. Importantly, biosynthesis of secondary metabolites and phenylalanine metabolism, which is of potential importance in coordinating freezing tolerance with growth and development, were downregulated in subzero temperatures. The adaptive mechanism for frost tolerance is a complex multigenic process that is not well understood. This systematic analysis provided an in-depth view of stress tolerance mechanisms in alfalfa.

  15. Transcription co-activator Arabidopsis ANGUSTIFOLIA3 (AN3) regulates water-use efficiency and drought tolerance by modulating stomatal density and improving root architecture by the transrepression of YODA (YDA).

    Science.gov (United States)

    Meng, Lai-Sheng; Yao, Shun-Qiao

    2015-09-01

    One goal of modern agriculture is the improvement of plant drought tolerance and water-use efficiency (WUE). Although stomatal density has been linked to WUE, the causal molecular mechanisms and engineered alternations of this relationship are not yet fully understood. Moreover, YODA (YDA), which is a MAPKK kinase gene, negatively regulates stomatal development. BR-INSENSITIVE 2 interacts with phosphorylates and inhibits YDA. However, whether YDA is modulated in the transcriptional level is still unclear. Plants lacking ANGUSTIFOLIA3 (AN3) activity have high drought stress tolerance because of low stomatal densities and improved root architecture. Such plants also exhibit enhanced WUE through declining transpiration without a demonstrable reduction in biomass accumulation. AN3 negatively regulated YDA expression at the transcriptional level by target-gene analysis. Chromatin immunoprecipitation analysis indicated that AN3 was associated with a region of the YDA promoter in vivo. YDA mutation significantly decreased the stomatal density and root length of an3 mutant, thus proving the participation of YDA in an3 drought tolerance and WUE enhancement. These components form an AN3-YDA complex, which allows the integration of water deficit stress signalling into the production or spacing of stomata and cell proliferation, thus leading to drought tolerance and enhanced WUE.

  16. A Mathematical Model for Freeze-Drying

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Based on the experiments on freeze-drying carrot and potato slabs, the effects of some parameters, such as heating temperature and pressure on the freeze-drying process are examined. A simple model of freeze-drying is established to predict drying time and the mass variations of materials during the drying. The experimental results agree well with those calculated by the model.

  17. 9 CFR 590.536 - Freezing operations.

    Science.gov (United States)

    2010-01-01

    ... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Freezing operations. 590.536 Section 590.536 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE EGG..., and Facility Requirements § 590.536 Freezing operations. (a) Freezing rooms shall be kept clean...

  18. The Study of the Participation of Heat Shock Proteins in the Resistance to High and Low Temperatures with the Use of Thellungiella (Thellungiella salsuguinea and Transgenic Lines of Arabidopsis (Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    K.Z. Gamburg

    2017-02-01

    Full Text Available Transgenic lines of Arabidopsis with HSP101 gene in sense and anti sense orientations acquired resistance to hard heat shock (50° C 10 min or 45-47° C 1 hour and to freezing (-4° C 2 hours due to the preliminary 2 hour’s heating at 37° C. Thus, it was shown at the first time that the induction of the resistance to hard heat shock and freezing with mild heat shock is possible in the absence of HSP101 synthesis. Thellungiella with the genome to 95-97% identical to the genome of Arabidopsis did not have higher resistance to high temperature, but was significantly more resistant to freezing. It differed from Arabidopsis by several times higher contents of HSP101, HSP60 and HSC70. Contents of these HSPs in Arabidopsis increased as a result of hardening at 4° C what was accompanied by the increase of the resistance to freezing. It is supposed that the resistances to heat and cold shocks are dependent not only from HSP101, but also from other HSPs.

  19. Differential SAGE analysis in Arabidopsis uncovers increased transcriptome complexity in response to low temperature

    Directory of Open Access Journals (Sweden)

    Parkin Isobel AP

    2008-09-01

    Full Text Available Abstract Background Abiotic stress, including low temperature, limits the productivity and geographical distribution of plants, which has led to significant interest in understanding the complex processes that allow plants to adapt to such stresses. The wide range of physiological, biochemical and molecular changes that occur in plants exposed to low temperature require a robust global approach to studying the response. We have employed Serial Analysis of Gene Expression (SAGE to uncover changes in the transcriptome of Arabidopsis thaliana over a time course of low temperature stress. Results Five SAGE libraries were generated from A. thaliana leaf tissue collected at time points ranging from 30 minutes to one week of low temperature treatment (4°C. Over 240,000 high quality SAGE tags, corresponding to 16,629 annotated genes, provided a comprehensive survey of changes in the transcriptome in response to low temperature, from perception of the stress to acquisition of freezing tolerance. Interpretation of these data was facilitated by representing the SAGE data by gene identifier, allowing more robust statistical analysis, cross-platform comparisons and the identification of genes sharing common expression profiles. Simultaneous statistical calculations across all five libraries identified 920 low temperature responsive genes, only 24% of which overlapped with previous global expression analysis performed using microarrays, although similar functional categories were affected. Clustering of the differentially regulated genes facilitated the identification of novel loci correlated with the development of freezing tolerance. Analysis of their promoter sequences revealed subsets of genes that were independent of CBF and ABA regulation and could provide a mechanism for elucidating complementary signalling pathways. The SAGE data emphasised the complexity of the plant response, with alternate pre-mRNA processing events increasing at low temperatures

  20. Salt Tolerance in Soybean

    Institute of Scientific and Technical Information of China (English)

    Tsui-Hung Phang; Guihua Shao; Hon-Ming Lam

    2008-01-01

    Soybean is an Important cash crop and its productivity is significantly hampered by salt stress. High salt Imposes negative impacts on growth, nodulation, agronomy traits, seed quality and quantity, and thus reduces the yield of soybean. To cope with salt stress, soybean has developed several tolerance mechanisms, including: (I) maintenance of ion homeostasis; (ii) adjustment in response to osmotic stress; (iii) restoration of osmotic balance; and (iv) other metabolic and structural adaptations. The regulatory network for abiotic stress responses in higher plants has been studied extensively in model plants such as Arabidopsis thaliana. Some homologous components involved in salt stress responses have been identified in soybean. In this review, we tried to integrate the relevant works on soybean and proposes a working model to descdbe Its salt stress responses at the molecular level.

  1. Freeze Technology for Nuclear Applications - 13590

    Energy Technology Data Exchange (ETDEWEB)

    Rostmark, Susanne C.; Knutsson, Sven [Lulea University of Technology (Sweden); Lindberg, Maria [Studsvik Nuclear AB, 611 82 Nykoeping (Sweden)

    2013-07-01

    Freezing of soil materials is a complicated process of a number of physical processes: - freezing of pore water in a thermal gradient, - cryogenic suction causing water migration and - ice formation expanding pores inducing frost heave. Structural changes due to increase of effective stress during freezing also take place. The over consolidation gives a powerful dewatering/drying effect and the freeze process causes separation of contaminates. Artificial ground freezing (AGF is a well established technique first practiced in south Wales, as early as 1862. AGF is mostly used to stabilize tunnels and excavations. During the last ten years underwater applications of freeze technologies based on the AGF have been explored in Sweden. The technology can, and has been, used in many different steps in a remediation action. Freeze Sampling where undisturbed samples are removed in both soft and hard sediment/sludge, Freeze Dredging; retrieval of sediment with good precision and minimal redistribution, and Freeze Drying; volume reduction of contaminated sludge/sediment. The application of these technologies in a nuclear or radioactive environment provides several advantages. Sampling by freezing gives for example an advantage of an undisturbed sample taken at a specified depth, salvaging objects by freezing or removal of sludges is other applications of this, for the nuclear industry, novel technology. (authors)

  2. The F130S point mutation in the Arabidopsis high-affinity K+ transporter AtHAK5 increases K+ over Na+ and Cs+ selectivity and confers Na+ and Cs+ tolerance to yeast under heterologous expression

    Directory of Open Access Journals (Sweden)

    Fernando eAleman

    2014-09-01

    Full Text Available Potassium (K+ is an essential macronutrient required for plant growth, development and high yield production of crops. Members of group I of the KT/HAK/KUP family of transporters, such as HAK5, are key components for K+ acquisition by plant roots at low external K+ concentrations. Certain abiotic stress conditions such as salinity or Cs+-polluted soils may jeopardize plant K+ nutrition because HAK5-mediated K+ transport is inhibited by Na+ and Cs+. Here, by screening in yeast a randomly-mutated collection of AtHAK5 transporters, a new mutation in AtHAK5 sequence is identified that greatly increases Na+ tolerance. The single point mutation F130S, affecting an amino acid residue conserved in HAK5 transporters from several species, confers high salt tolerance, as well as Cs+ tolerance. This mutation increases more than 100-fold the affinity of AtHAK5 for K+ and reduces the Ki values for Na+ and Cs+, suggesting that the F130 residue may contribute to the structure of the pore region involved in K+ binding. In addition, this mutation increases the Vmax for K+. All this changes occur without increasing the amount of the AtHAK5 protein in yeast and support the idea that this residue is contributing to shape the selectivity filter of the AtHAK5 transporter.

  3. Extreme flooding tolerance in Rorippa.

    Science.gov (United States)

    Akman, Melis; Bhikharie, Amit; Mustroph, Angelika; Sasidharan, Rashmi

    2014-01-01

    Low oxygen stress imposed by floods creates a strong selection force shaping plant ecosystems in flood-prone areas. Plants inhabiting these environments adopt various adaptations and survival strategies to cope with increasing water depths. Two Rorippa species, R. sylvestris and R. amphibia that grow in naturally flooded areas, have high submergence tolerance achieved by the so-called quiescence and escape strategies, respectively. In order to dissect the molecular mechanisms involved in these strategies, we investigated submergence-induced changes in gene expression in flooded roots of Rorippa species. There was a higher induction of glycolysis and fermentation genes and faster carbohydrate reduction in R. amphibia, indicating a higher demand for energy potentially leading to faster mortality by starvation. Moreover, R. sylvestris showed induction of genes improving submergence tolerance, potentially enhancing survival in prolonged floods. Additionally, we compared transcript profiles of these 2 tolerant species to relatively intolerant Arabidopsis and found that only Rorippa species induced various inorganic pyrophosphate dependent genes, alternatives to ATP demanding pathways, thereby conserving energy, and potentially explaining the difference in flooding survival between Rorippa and Arabidopsis.

  4. Adaptation to seasonality and the winter freeze

    Directory of Open Access Journals (Sweden)

    Jill Christine Preston

    2013-06-01

    Full Text Available Flowering plants initially diversified during the Mesozoic era at least 140 million years ago in regions of the world where temperate seasonal environments were not encountered. Since then several cooling events resulted in the contraction of warm and wet environments and the establishment of novel temperate zones in both hemispheres. In response, less than half of modern angiosperm families have members that evolved specific adaptations to cold seasonal climates, including cold acclimation, freezing tolerance, endodormancy, and vernalization responsiveness. Despite compelling evidence for multiple independent origins, the level of genetic constraint on the evolution of adaptations to seasonal cold is not well understood. However, the recent increase in molecular genetic studies examining the response of model and crop species to seasonal cold offers new insight into the evolutionary lability of these traits. This insight has major implications for our understanding of complex trait evolution, and the potential role of local adaptation in response to past and future climate change. In this review, we discuss the biochemical, morphological, and developmental basis of adaptations to seasonal cold, and synthesize recent literature on the genetic basis of these traits in a phylogenomic context. We find evidence for multiple genetic links between distinct physiological responses to cold, possibly reinforcing the coordinated expression of these traits. Furthermore, repeated recruitment of the same or similar ancestral pathways suggests that land plants might be somewhat pre-adapted to dealing with temperature stress, perhaps making inducible cold traits relatively easy to evolve.

  5. Disruption of Arabidopsis CHY1 Reveals an Important Role of Metabolic Status in Plant Cold Stress Signaling

    Institute of Scientific and Technical Information of China (English)

    Chun-Hai Dong; Bethany K. Zolman; Bonnie Bartel; Byeong-ha Lee; Becky Stevenson; Manu Agarwal; Jian-Kang Zhu

    2009-01-01

    To study cold signaling, we screened for Arabidopsis mutants with altered cold-induced transcription of a firefly luciferase reporter gene driven by the CBF3 promoter (CBF3-LUC). One mutant, chyl-10, displayed reduced cold-induction of CBF3-LUC luminescence. RNA gel blot analysis revealed that expression of endogenous CBFs also was reduced in the chy1 mutant, chyl-10 mutant plants are more sensitive to freezing treatment than wild-type after cold acclimation. Both the wild-type and chy1 mutant plants are sensitive to darkness-induced starvation at warm temperatures, although chy1 plants are slightly more sensitive. This dark-sensitivity is suppressed by cold temperature in the wildtype but not in chy1. Constitutive CBF3 expression partially rescues the sensitivity of chy1-10 plants to dark treatment in the cold. The chy1 mutant accumulates higher levels of reactive oxygen species, and application of hydrogen peroxide can reduce cold-induction of CBF3-LUC in wild-type. Map-based cloning of the gene defective in the mutant revealed a nonsense mutation in CHY1, which encodes a peroxisomal β-hydroxyisobutyryl (HIBYL)-CoA hydrolase needed for valine catabolism and fatty acid β-oxidation. Our results suggest a role for peroxisomal metabolism in cold stress signaling, and plant tolerance to cold stress and darkness-induced starvation.

  6. Transgenic tobacco plants accumulating osmolytes show reduced oxidative damage under freezing stress.

    Science.gov (United States)

    Parvanova, Daniela; Ivanov, Sergei; Konstantinova, Tatyana; Karanov, Emanuil; Atanassov, Atanas; Tsvetkov, Tsvetan; Alexieva, Vera; Djilianov, Dimitar

    2004-01-01

    We studied the reaction to the oxidative component of freezing in several tobacco lines, transformed with genes coding for enzymes involved in the synthesis of osmoprotectants (proline, fructan or glycine betaine) along with their wild type. The levels of some oxidative stress markers (leakage of electrolytes, hydrogen peroxide and malondialdehyde) as well as the activity of antioxidative enzymes catalase (EC 1.11.1.6.) and guaiacol peroxidase (EC 1.11.1.7.) have been followed at acclimation, 12 and 24 h freezing and at recovery. Freezing for 24 h resulted in severe damages for the wild type. A corresponding increase of electrolyte leakage, hydrogen peroxide and malondialdehyde contents, a rise of peroxidase activity and inhibition of catalase activity occurred in the non-transformants. Similar, but significantly lower trend of the same parameters has been found for the transgenic lines. Moreover, the oxidative markers returned to their normal levels when the transformants were able to recover from freezing. It could be speculated that transfer of genes, coding for accumulation of osmoprotectants, is related to reduced intensity of freezing-induced oxidative processes. Our lines and model system could serve as a good prerequisite for additional studies to gain further insights into the complex role of osmoprotectants in freezing tolerance.

  7. Fundamental Technical Elements of Freeze-fracture/Freeze-etch in Biological Electron Microscopy

    Science.gov (United States)

    Freeze-fracture/freeze-etch describes a process whereby specimens, typically biological or nanomaterial in nature, are frozen, fractured, and replicated to generate a carbon/platinum "cast" intended for examination by transmission electron microscopy. Specimens are subjected to u...

  8. When hot water freezes before cold

    CERN Document Server

    Katz, J I

    2006-01-01

    I suggest that the origin of the Mpemba effect (the freezing of hot water before cold) is freezing-point depression by solutes, either gaseous or solid, whose solubility decreases with increasing temperature so that they are removed when water is heated. They are concentrated ahead of the freezing front by zone refining in water that has not been heated, reduce the temperature of the freezing front, and thereby reduce the temperature gradient and heat flux, slowing the progress of the front. I present a simple calculation of this effect, and suggest experiments to test this hypothesis.

  9. Infective Juveniles of the Entomopathogenic Nematode, Steinernema feltiae Produce Cryoprotectants in Response to Freezing and Cold Acclimation.

    Science.gov (United States)

    Ali, Farman; Wharton, David A

    2015-01-01

    Steinernema feltiae is a moderately freeze-tolerant entomopathogenic nematode which survives intracellular freezing. We have detected by gas chromatography that infective juveniles of S. feltiae produce cryoprotectants in response to cold acclimation and to freezing. Since the survival of this nematode varies with temperature, we analyzed their cryoprotectant profiles under different acclimation and freezing regimes. The principal cryoprotectants detected were trehalose and glycerol with glucose being the minor component. The amount of cryoprotectants varied with the temperature and duration of exposure. Trehalose was accumulated in higher concentrations when nematodes were acclimated at 5°C for two weeks whereas glycerol level decreased from that of the non-acclimated controls. Nematodes were seeded with a small ice crystal and held at -1°C, a regime that does not produce freezing of the nematodes but their bodies lose water to the surrounding ice (cryoprotective dehydration). This increased the levels of both trehalose and glycerol, with glycerol reaching a higher concentration than trehalose. Nematodes frozen at -3°C, a regime that produces freezing of the nematodes and results in intracellular ice formation, had elevated glycerol levels while trehalose levels did not change. Steinernema feltiae thus has two strategies of cryoprotectant accumulation: one is an acclimation response to low temperature when the body fluids are in a cooled or supercooled state and the infective juveniles produce trehalose before freezing. During this process a portion of the glycerol is converted to trehalose. The second strategy is a rapid response to freezing which induces the production of glycerol but trehalose levels do not change. These low molecular weight compounds are surmised to act as cryoprotectants for this species and to play an important role in its freezing tolerance.

  10. Freezing and thawing of processed meat in an industrial freezing tunnel

    Directory of Open Access Journals (Sweden)

    Glaucio Antonio Marini

    2014-04-01

    Full Text Available Freezing is a commonly used preservation method in the meat industry. The understanding of the product behavior during the freezing process can assist in a better process management and quality control. This work reports the study of freezing and thawing of three types of processed meat in order to determine process parameters in an industrial forced‑air freezing tunnel at ‑30oC. Chicken sausages (frankfurter type, mortadela (bologna type and mechanically deboned chicken meat (MDCM were studied. Products were placed in several layers in corrugated cardboard boxes (CCB for sausages and mortadela. MDCM was placed in a nylon box. Temperature sensors were inserted in the products and the freezing and thawing curves were obtained. Freezing curves were used to determine the freezing time (tf, initial freezing point (Tf and final freezing point (T’m. Products placed in different layers in the CCB had significantly different freezing times, being the higher rates for products placed in more external layers than internal ones. The external layers of product were subjected to heat transfer by convection showing its importance to decrease freezing time. The results strongly suggest that products placed in different layers could have distinct quality properties and also play a key role in the freezing process efficiency.

  11. Mechanisms of deterioration of nutrients. [of freeze dried foods

    Science.gov (United States)

    Karel, M.; Flink, J. M.

    1976-01-01

    Methods which produce freeze dried foods of improved quality were examined with emphasis on storage stability. Specific topics discussed include: microstructure of freeze dried systems, investigation of structural changes in freeze dried systems, artificial food matrices, osmotic preconcentration to yield improved quality freeze dried fruits, and storage stability of osmotically preconcentrated freeze dried fruits.

  12. Reference: 517 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available d isolated aleurone layers of Arabidopsis (Arabidopsis thaliana) were used in experiments designed to iden...tify components of the Arabidopsis seed that contribute to seed dormancy and to lea

  13. ESKIMO1 disruption in Arabidopsis alters vascular tissue and impairs water transport.

    Directory of Open Access Journals (Sweden)

    Valérie Lefebvre

    Full Text Available Water economy in agricultural practices is an issue that is being addressed through studies aimed at understanding both plant water-use efficiency (WUE, i.e. biomass produced per water consumed, and responses to water shortage. In the model species Arabidopsis thaliana, the ESKIMO1 (ESK1 gene has been described as involved in freezing, cold and salt tolerance as well as in water economy: esk1 mutants have very low evapo-transpiration rates and high water-use efficiency. In order to establish ESK1 function, detailed characterization of esk1 mutants has been carried out. The stress hormone ABA (abscisic acid was present at high levels in esk1 compared to wild type, nevertheless, the weak water loss of esk1 was independent of stomata closure through ABA biosynthesis, as combining mutant in this pathway with esk1 led to additive phenotypes. Measurement of root hydraulic conductivity suggests that the esk1 vegetative apparatus suffers water deficit due to a defect in water transport. ESK1 promoter-driven reporter gene expression was observed in xylem and fibers, the vascular tissue responsible for the transport of water and mineral nutrients from the soil to the shoots, via the roots. Moreover, in cross sections of hypocotyls, roots and stems, esk1 xylem vessels were collapsed. Finally, using Fourier-Transform Infrared (FTIR spectroscopy, severe chemical modifications of xylem cell wall composition were highlighted in the esk1 mutants. Taken together our findings show that ESK1 is necessary for the production of functional xylem vessels, through its implication in the laying down of secondary cell wall components.

  14. Effects of diapause and cold-acclimation on the avoidance of freezing injury in fat body tissue of the rice stem borer, Chilo suppressalis Walker.

    Science.gov (United States)

    Izumi, Yohei; Sonoda, Shoji; Tsumuki, Hisaaki

    2007-07-01

    Overwintering freeze-tolerant larvae of Chilo suppressalis can survive at -25 degrees C, but non-diapausing larvae cannot. We reported earlier that to prevent intracellular freezing, which causes death in overwintering larvae of the Saigoku ecotype distributed in southwestern Japan, water leaves and glycerol enters fat body cells through water channels during freezing. However, it is still unclear how diapause and low-temperature exposure are related to the acquisition of freeze tolerance. We compared the extent of tissue damage, accumulation of glycerol, and transport of glycerol and water in fat body tissues between cold-acclimated and non-acclimated non-diapausing and diapausing larvae. The tissue from cold-acclimated diapausing larvae could survive only when frozen in Grace's insect medium with 0.25 M glycerol at -20 degrees C. The protection provided by glycerol was offset by mercuric chloride, which is a water-channel inhibitor. Fat body tissue isolated from non-acclimated diapausing larvae was injured by freezing even though glycerol was added to the medium, but the level of freezing injury was significantly lower than in non-diapausing larvae. Radiotracer assays in cold-acclimated diapausing larvae showed that during freezing, water left the cells into the medium and glycerol entered the cells from the medium at the same time. Therefore, in Saigoku ecotype larvae of the rice stem borer, both diapause and cold-acclimation are essential to accumulate glycerol and activate aquaporin for the avoidance of freezing injury.

  15. Proteomic study of low-temperature responses in strawberry cultivars (Fragaria x ananassa) that differ in cold tolerance.

    Science.gov (United States)

    Koehler, Gage; Wilson, Robert C; Goodpaster, John V; Sønsteby, Anita; Lai, Xianyin; Witzmann, Frank A; You, Jin-Sam; Rohloff, Jens; Randall, Stephen K; Alsheikh, Muath

    2012-08-01

    To gain insight into the molecular basis contributing to overwintering hardiness, a comprehensive proteomic analysis comparing crowns of octoploid strawberry (Fragaria × ananassa) cultivars that differ in freezing tolerance was conducted. Four cultivars were examined for freeze tolerance and the most cold-tolerant cultivar ('Jonsok') and least-tolerant cultivar ('Frida') were compared with a goal to reveal how freezing tolerance is achieved in this distinctive overwintering structure and to identify potential cold-tolerance-associated biomarkers. Supported by univariate and multivariate analysis, a total of 63 spots from two-dimensional electrophoresis analysis and 135 proteins from label-free quantitative proteomics were identified as significantly differentially expressed in crown tissue from the two strawberry cultivars exposed to 0-, 2-, and 42-d cold treatment. Proteins identified as cold-tolerance-associated included molecular chaperones, antioxidants/detoxifying enzymes, metabolic enzymes, pathogenesis-related proteins, and flavonoid pathway proteins. A number of proteins were newly identified as associated with cold tolerance. Distinctive mechanisms for cold tolerance were characterized for two cultivars. In particular, the 'Frida' cold response emphasized proteins specific to flavonoid biosynthesis, while the more freezing-tolerant 'Jonsok' had a more comprehensive suite of known stress-responsive proteins including those involved in antioxidation, detoxification, and disease resistance. The molecular basis for 'Jonsok'-enhanced cold tolerance can be explained by the constitutive level of a number of proteins that provide a physiological stress-tolerant poise.

  16. Freeze conditioning agents ease winter railcar unloading

    Energy Technology Data Exchange (ETDEWEB)

    Olson, G.E.

    1982-02-01

    A US midwest utility's freeze control programme is described. All coal is treated with a glycol-based freeze control agent. Some rail wagons were treated with a side release agent which stops coal sticking to the metal wagon. The use of calcium chloride or heat to thaw frozen coal is also discussed.

  17. Updating freeze: Aligning animal and human research

    NARCIS (Netherlands)

    Hagenaars, M.A.; Oitzl, M.S.; Roelofs, K.

    2014-01-01

    Freezing is widely used as the main outcome measure for fear in animal studies. Freezing is also getting attention more frequently in human stress research, as it is considered to play an important role in the development of psychopathology. Human models on defense behavior are largely based on anim

  18. Repeatability and randomness in heterogeneous freezing nucleation

    Directory of Open Access Journals (Sweden)

    G. Vali

    2008-08-01

    Full Text Available This study is aimed at clarifying the relative importance of the specific character of the nuclei and of the duration of supercooling in heterogeneous freezing nucleation by immersed impurities. Laboratory experiments were carried out in which sets of water drops underwent multiple cycles of freezing and melting. The drops contained suspended particles of mixtures of materials; the resulting freezing temperatures ranged from −6°C to −24°C. Rank correlation coefficients between observed freezing temperatures of the drops in successive runs were >0.9 with very high statistical significance, and thus provide strong support for the modified singular model of heterogeneous immersion freezing nucleation. For given drops, changes in freezing temperatures between cycles were relatively small (<1°C for the majority of the events. These frequent small fluctuations in freezing temperatures are interpreted as reflections of the random nature of embryo growth and are associated with a nucleation rate that is a function of a temperature difference from the characteristic temperatures of nuclei. About a sixth of the changes were larger, up to ±5°C, and exhibited some systematic patterns. These are thought to arise from alterations of the nuclei, some being permanent and some transitory. The results are used to suggest ways of describing ice initiation in cloud models that account for both the temperature and the time dependence of freezing nucleation.

  19. Repeatability and randomness in heterogeneous freezing nucleation

    Directory of Open Access Journals (Sweden)

    G. Vali

    2008-02-01

    Full Text Available This study is aimed at clarifying the relative importance of the specific character of the nuclei and of the duration of supercooling in heterogeneous freezing nucleation by immersed impurities. Laboratory experiments were carried out in which sets of water drops underwent multiple cycles of freezing and melting. The drops contained suspended particles of mixtures of materials; the resulting freezing temperatures ranged from −6°C to −24°C. Rank correlation coefficients between observed freezing temperatures of the drops in successive runs were >0.9 with very high statistical significance, and thus provide strong support for the modified singular model of heterogeneous immersion freezing nucleation. For given drops, changes in freezing temperatures between cycles were relatively small (<1°C for the majority of the events. These frequent small fluctuations in freezing temperatures are interpreted as reflections of the random nature of embryo growth and are associated with a nucleation rate that is a function of a temperature difference from the characteristic temperatures of nuclei. About a sixth of the changes were larger, up to ±5°C, and exhibited some systematic patterns. These are thought to arise from alterations of the nuclei, some being permanent and some transitory. The results are used to suggest ways of describing ice initiation in cloud models that account for both the temperature and the time dependence of freezing nucleation.

  20. Impregnation of leather during "freeze-drying"

    DEFF Research Database (Denmark)

    Storch, Mikkel; Vestergaard Poulsen Sommer, Dorte; Hovmand, Ida;

    2016-01-01

    Freeze-drying is a recognized method for the preservation of waterlogged objects. Naturally, freeze-drying has also been used for waterlogged archaeological leather often after treatment with Na2.EDTA and impregnation with PEG; but the treated leather sometimes suffers from “excessive drying......” becoming too stiff and brittle. The aim of this study was to examine the effect of a conventional freeze-drying method against an alternative freeze-drying method that preserves the natural moisture content of the leather. Both new and archaeological waterlogged leather were included in the study...... and the leather samples were treated in one of four ways: pre-treatment with Na2EDTA, impregnation with PEG 400, pre-treatment with Na2EDTA followed by impregnation with PEG 400 as well as no treatment. After the treatments, the leather samples were freeze-dried either by the conventional or by the alternative...

  1. Monitoring the freezing point of buffalo milk

    Directory of Open Access Journals (Sweden)

    Antonella Pesce

    2016-05-01

    Full Text Available The aim of this study was to evaluate the basic freezing point of buffalo milk. Bulk milk samples were collected from buffalo and cattle farms in Caserta area from 2008 to 2014. The analysis involved a total of 1886 buffalo milk samples and 1711 bovine milk samples. These were also tested for fat, protein and lactose contents by means of infrared spectrometry. The freezing point was determined by means of a thermistor cryoscope. Data underwent statistical analysis. Our research showed an average freezing point of -0.528°C for buffalo milk and - 0.522°C for bovine milk. Given the lack of data on the freezing point of buffalo milk, our study provides the first indication of a basic freezing point of the milk of this species in Italy.

  2. Freeze concentration of lime juice

    Directory of Open Access Journals (Sweden)

    Ampawan Tansakul

    2008-11-01

    Full Text Available The main objective of this research was to study the effects of processing conditions, i.e. cooling medium temperature (-6, -12 and -18C and scraper blade rotational speed (50, 100 and 150 rpm on the freeze concentration of lime juice. The initial soluble solid content of lime juice was 7.6 Brix. Results showed that soluble solid content of lime juice increased as cooling medium temperature decreased while scraper blade rotational speed increased. It was also found that the processing condition with -18˚C cooling medium temperature and 150 rpm rotational speed of the scraper blade was the best among all studied conditions, although the loss of the soluble solids with ice crystals during ice separation was relatively high at 35%.

  3. Food freezing with simultaneous surface dehydration: approximate prediction of freezing time

    Energy Technology Data Exchange (ETDEWEB)

    Campanone, Laura A.; Salvadori, Viviana O.; Mascheroni, Rodolfo H. [Centro de Investigacion Desarollo en Criotecnologia de Alimentos (CIDCA), Facultad de Ciencias Exactas, La Plata (Argentina); MODIAL, Facultad de Ingenieria, La Plata (Argentina)

    2005-03-01

    Freezing of unpackaged foods induces mass transfer in the form of surface ice sublimation, which in turn modifies heat transfer conditions. At present there are no simplified methods for predicting freezing times when surface dehydration occurs. This paper uses a previously developed model for the simulation of simultaneous heat and mass transfer during food freezing and storage to generate a complete set of predicted freezing times when dehydration occurs. Based on these data a simplified analytical method for the prediction of freezing time during freezing of unpackaged frozen foods was developed. The method accounts for product characteristics (shape, size and composition) and operating conditions (initial and refrigerant temperature, heat transfer coefficient, relative humidity). The prediction equation is very simple and results of its use - simulating usual freezing conditions for different products - shows very good accuracy when tested against the previously cited numerical model and all the available experimental data. (Author)

  4. Om tolerance

    DEFF Research Database (Denmark)

    Huggler, Jørgen

    2007-01-01

    Begrebet tolerance og dets betydninger diskuteres med henblik på en tydeliggørelse af begrebets forbindelse med stat, religion, ytringsfrihed, skeptisk erkendelsesteori, antropologi og pædagogik.......Begrebet tolerance og dets betydninger diskuteres med henblik på en tydeliggørelse af begrebets forbindelse med stat, religion, ytringsfrihed, skeptisk erkendelsesteori, antropologi og pædagogik....

  5. 3D Reconstruction of Frozen Plant Tissue: a unique histological analysis to image post-freeze responses

    Science.gov (United States)

    Winter hardiness in plants is the result of a complex interaction between genes, the tissue where those genes are expressed and the environment. The light microscope is a valuable tool to understand this complexity which will ultimately help researchers improve the tolerance of plants to freezing st...

  6. Overexpression of Arabidopsis MiR396 Enhances Drought Tolerance in Transgenic Tobacco Plants%高表达拟南芥miR396提高烟草抗旱性

    Institute of Scientific and Technical Information of China (English)

    杨凤玺; 余迪求

    2009-01-01

    MiR396是一个由21个核苷酸组成的单链非编码RNA小分子.烟草内的miR396受干旱诱导说明其可能参与烟草的干旱应答.在35S强启动子作用下我们将miR396转入到烟草体内获得高表达转基因植株,生理学测试表明高表达miR396的转基因烟草耐旱性增强,同时叶片表现出比野生型较低的失水率和较高的相对含水量,进一步分析表明转基因植株除了叶片变得更为窄小外,其气孔密度和气孔系数都比野生型降低,这些都表明miR396作为一个正调节因子参与烟草的干旱胁迫应答.%MiR396 was a single-stranded noncoding small RNA with 21 nucleotides, and the expression of MiR369 in leaves was strongly induced in water deficit condition in tobacco, which suggested a possible role of miR396 in drought stress response. Under the control of 35S promoter, MIR396 was introduced into tobacco mediated by Agrobacterium tumefaciens. Physiological tests indicated that the elevated levels of miR396 increased drought tolerance in tobacco accompanying with lower water loss rate and higher relative water content. Further more miR396-overexpressing plants exhibited visible reductions both in stomatal density and stomatal index as well as a narrow and small leaf phenotype in comparison with wild-type plants. The present study indicated that miR396 was a positive regulator in response to drought stress in tobacco.

  7. Exploring the Nature of Contact Freezing

    Science.gov (United States)

    Kiselev, A. A.; Hoffmann, N.; Duft, D.; Leisner, T.

    2012-12-01

    The freezing of supercooled water droplets upon contact with aerosol particles (contact nucleation of ice) is the least understood mechanism of ice formation in atmospheric clouds. Although experimental evidences suggest that some aerosols can be better IN in the contact than in the immersion mode (that is, triggering ice nucleation at higher temperature), no final explanation of this phenomena currently exists. On the other hand, the contact freezing is believed to be responsible for the enhanced rate of secondary ice formation occasionally observed in LIDAR measurements in the cold mixed phase clouds. Recently we have been able to show that the freezing of supercooled droplets electrodynamically levitated in the laminar flow containing mineral dust particles (kaolinite) is a process solely governed by a rate of collisions between the supercooled droplet and the aerosol particles. We have shown that the probability of droplet freezing on a single contact with aerosol particle may differ over an order of magnitude for kaolinite particles having different genesis and morphology. In this presentation we extend the study of contact nucleation of ice and compare the IN efficiency measured for DMA-selected kaolinite, illite and hematite particles. We show that the freezing probability increases towards unity as the temperature decreases and discuss the functional form of this temperature dependence. We explore the size dependence of the contact freezing probability and show that it scales with the surface area of the particles, thus resembling the immersion freezing behavior. However, for all minerals investigated so far, the contact freezing has been shown to dominate over immersion freezing on the short experimental time scales. Finally, based on the combined ESEM and electron microprobe analysis, we discuss the significance of particle morphology and variability of chemical composition on its IN efficiency in contact mode.

  8. ESKIMO1 is a key gene involved in water economy as well as cold acclimation and salt tolerance

    Directory of Open Access Journals (Sweden)

    Yu Agnes

    2008-12-01

    Full Text Available Abstract Background Drought is a major social and economic problem resulting in huge yield reduction in the field. Today's challenge is to develop plants with reduced water requirements and stable yields in fluctuating environmental conditions. Arabidopsis thaliana is an excellent model for identifying potential targets for plant breeding. Drought tolerance in the field was successfully conferred to crops by transferring genes from this model species. While involved in a plant genomics programme, which aims to identify new genes responsible for plant response to abiotic stress, we identified ESKIMO1 as a key gene involved in plant water economy as well as cold acclimation and salt tolerance. Results All esk1 mutants were more tolerant to freezing, after acclimation, than their wild type counterpart. esk1 mutants also showed increased tolerance to mild water deficit for all traits measured. The mutant's improved tolerance to reduced water supply may be explained by its lower transpiration rate and better water use efficiency (WUE, which was assessed by carbon isotope discrimination and gas exchange measurements. esk1 alleles were also shown to be more tolerant to salt stress. Transcriptomic analysis of one mutant line and its wild-type background was carried out. Under control watering conditions a number of genes were differentially expressed between the mutant and the wild type whereas under mild drought stress this list of genes was reduced. Among the genes that were differentially expressed between the wild type and mutant, two functional categories related to the response to stress or biotic and abiotic stimulus were over-represented. Under salt stress conditions, all gene functional categories were represented equally in both the mutant and wild type. Based on this transcriptome analysis we hypothesise that in control conditions the esk1 mutant behaves as if it was exposed to drought stress. Conclusion Overall our findings suggest that the

  9. Ice encapsulation protects rather than disturbs the freezing lichen.

    Science.gov (United States)

    Bjerke, J W

    2009-03-01

    Arctic and alpine terricolous lichens are adapted to harsh environments and are tolerant to extremely low temperatures when metabolically inactive. However, there are reports indicating that freezing can be lethal to metabolically active lichens. With a projected warmer and more unstable climate, winter precipitation at high latitudes will fall more frequently as rain, causing snowmelt and encapsulating terricolous lichens in ice or exposing them to large temperature fluctuations. Lichens are a major winter food source for reindeer in most parts of the circumpolar region. A laboratory experiment tested how three hydrated reindeer forage lichen species covered by snow, encapsulated in ice, or uncovered responded to storage at freezing temperatures and subsequent warming. Photosynthetic performance (maximal fluorescence of dark-adapted samples and net photosynthetic rates) was significantly lower in lichens not insulated by snow or ice, whereas there were few differences between the snow and ice treatments. It is suggested that snow and ice provide sufficiently moist environments to improve extracellular and reduce intracellular ice nucleation activity. Ice encapsulation, which is often lethal to vascular plants, did not have any negative effects on the studied lichens. The results indicate that complete snow and ice melt followed by refreezing can be detrimental to terricolous lichen ecosystems. Reduced lichen biomass will have a negative effect both on reindeer winter survival and the indigenous peoples who herd reindeer.

  10. Evaluation of spin freezing versus conventional freezing as part of a continuous pharmaceutical freeze-drying concept for unit doses.

    Science.gov (United States)

    De Meyer, L; Van Bockstal, P-J; Corver, J; Vervaet, C; Remon, J P; De Beer, T

    2015-12-30

    Spin-freezing as alternative freezing approach was evaluated as part of an innovative continuous pharmaceutical freeze-drying concept for unit doses. The aim of this paper was to compare the sublimation rate of spin-frozen vials versus traditionally frozen vials in a batch freeze-dryer, and its impact on total drying time. Five different formulations, each having a different dry cake resistance, were tested. After freezing, the traditionally frozen vials were placed on the shelves while the spin-frozen vials were placed in aluminum vial holders providing radial energy supply during drying. Different primary drying conditions and chamber pressures were evaluated. After 2h of primary drying, the amount of sublimed ice was determined in each vial. Each formulation was monitored in-line using NIR spectroscopy during drying to determine the sublimation endpoint and the influence of drying conditions upon total drying time. For all tested formulations and applied freeze-drying conditions, there was a significant higher sublimation rate in the spin-frozen vials. This can be explained by the larger product surface and the lower importance of product resistance because of the much thinner product layers in the spin frozen vials. The in-line NIR measurements allowed evaluating the influence of applied drying conditions on the drying trajectories.

  11. Harnessing the energy accompanying freezing

    Energy Technology Data Exchange (ETDEWEB)

    Akyurt, M., E-mail: makyurt@kau.edu.s [Departments of Mechanical Engineering, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Tuerkmen, N. [Departments of Mechanical Engineering, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)

    2011-05-15

    Research highlights: {yields} Ice pressurization allows the burst and leak testing of practically all tubular materials. {yields} The assembly can be made fully portable for maintenance operations without the use of liquid CO{sub 2} and N{sub 2}. {yields} Ice pressurization can work where conventional interference fitting, axial pressing and heat treatment fail. {yields} Uniform pressures can be developed in ice pressurization as opposed to Herzian distributions under plungers. -- Abstract: The progression of freezing of water inside a pipe is reviewed, with special emphasis on bursting. The process of pressure rise in confined bodies of water is discussed. The development of a method utilizing liquid carbon dioxide and liquid nitrogen, for the development of pressures inside closed containers is summarized. Then a novel method, utilizing mechanical refrigeration, is explained for the generation of high pressures. An experimental setup for the latter technique is described and results of experiments are summarized. A number of ways of utilizing the ice-pressurization technique are presented. Certain characteristics and advantages of ice-pressurization are enumerated as regards to burst and leak testing. It is noted that a number of other techniques such as shrink fitting, embossing and compaction of powders also seem to be particularly suitable. It is concluded that, with the advent of the portable and novel chilling apparatus, new vistas are approachable for undertaking maintenance operations in hospitals, power plants, nuclear facilities, and other systems that require uninterrupted operation.

  12. The Influence of Freezing Drizzle on Wire Icing during Freezing Fog Events

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yue; NIU Shengjie; L(U) Jingjing

    2013-01-01

    Both direct and indirect effects of freezing drizzle on ice accretion were analyzed for ten freezing drizzle events during a comprehensive ice thickness,fog,and precipitation observation campaign carried out during the winter of 2008 and 2009 at Enshi Radar Station (30°17′N,109°16′E),Hubei Province,China.The growth rate of ice thickness was 0.85 mm h-1 during the freezing drizzle period,while the rate was only 0.4 mm h-1 without sleet and freezing drizzle.The rain intensity,liquid water content (LWC),and diameter of freezing drizzle stayed at low values.The development of microphysical properties of fog was suppressed in the freezing drizzle period.A threshold diameter (Dc) was proposed to estimate the influence of freezing drizzle on different size ranges of fog droplets.Fog droplets with a diameter less than Dc would be affected slightly by freezing drizzle,while larger fog droplets would be affected significantly.Dc had a correlation with the average rain intensity,with a correlation coefficient of 0.78.The relationships among the microphysical properties of fog droplets were all positive when the effect of freezing drizzle was weak,while they became poor positive correlations,or even negative correlations during freezing drizzle period.The direct contribution of freezing drizzle to ice thickness was about 14.5%.Considering both the direct and indirect effects,we suggest that freezing drizzle could act as a “catalyst” causing serious icing conditions.

  13. Freezing phenomena in ice-water systems

    Energy Technology Data Exchange (ETDEWEB)

    Akyurt, M.; Zaki, G.; Habeebullah, B. [Fakieh Center for Applied Research, Makkah Al-Mukarramah (Saudi Arabia); King Abdulaziz University, Jeddah (Saudi Arabia). Dept. of Mechanical Engineering

    2002-09-01

    The characteristics of solidification and melting are reviewed. The properties of water and ice and the phase diagram of water are discussed with special emphasis on ice density. A concise account of the freezing process and the Stefan problem is presented. To this end, the four stages of freezing are identified, supercooling, nucleation and the formation of dendritic ice, the growth of concentric rings of solid ice at 0{sup o}C and the final cooling of the solid ice are treated in some detail. The subject of bursting of pipes is given particular emphasis. Attention is drawn to a common misconception on pipe bursting and to misleading relationships for the computation of freezing time for ice blockage. Several current applications of melting and freezing systems are outlined. (author)

  14. Snow Melting and Freezing on Older Townhouses

    DEFF Research Database (Denmark)

    Nielsen, Anker; Claesson, Johan

    2011-01-01

    The snowy winter of 2009/2010 in Scandinavia prompted many newspaper articles on icicles falling from buildings and the risk this presented for people walking below. The problem starts with snow melting on the roof due to heat loss from the building. Melt water runs down the roof and some...... of it will freeze on the overhang. The rest of the water will either run off or freeze in gutters and downpipes or turn into icicles. This paper describes use of a model for the melting and freezing of snow on roofs. Important parameters are roof length, overhang length, heat resistance of roof and overhang......, outdoor and indoor temperature, snow thickness and thermal conductivity. If the snow thickness is above a specific limit value – the snow melting limit- some of the snow will melt. Another interesting limit value is the dripping limit. All the melt water will freeze on the overhang, if the snow thickness...

  15. Freezing of water droplets colliding with kaolinite particles

    DEFF Research Database (Denmark)

    Svensson, Erik Anders; Delval, Christophe Eric Ludovic; Freiherr von Und zu Hessberg, P J H;

    2009-01-01

    Contact freezing of single supercooled water droplets colliding with kaolinite dust particles has been investigated. The experiments were performed with droplets levitated in an electrodynamic balance at temperatures from 240 to 268 K. Under dry conditions freezing 5 was observed to occur below 2...... studies to describe freezing rates are appropriate for kaolinite aerosol particles. Mechanisms for contact freezing are briefly discussed....

  16. Repressive Tolerance

    DEFF Research Database (Denmark)

    Pedersen, Morten Jarlbæk

    2016-01-01

    to an administrative culture of repressive tolerance of organised interests: authorities listen but only reacts in a very limited sense. This bears in it the risk of jeopardising the knowledge transfer from societal actors to administrative ditto thus harming the consultation institutions’ potential for strengthening...

  17. Towards Tolerance

    NARCIS (Netherlands)

    Lisette Kuyper; Jurjen Iedema; Saskia Keuzenkamp

    2013-01-01

    Across Europe, public attitudes towards lesbian, gay and bisexual (LGB) individuals range from broad tolerance to widespread rejection. Attitudes towards homosexuality are more than mere individual opinions, but form part of the social and political structures which foster or hinder the equality and

  18. Isochoric and isobaric freezing of fish muscle.

    Science.gov (United States)

    Năstase, Gabriel; Lyu, Chenang; Ukpai, Gideon; Șerban, Alexandru; Rubinsky, Boris

    2017-02-19

    We have recently shown that, a living organism, which succumbs to freezing to -4 °C in an isobaric thermodynamic system (constant atmospheric pressure), can survive freezing to -4 °C in an isochoric thermodynamic system (constant volume). It is known that the mechanism of cell damage in an isobaric system is the freezing caused increase in extracellular osmolality, and, the consequent cell dehydration. An explanation for the observed survival during isochoric freezing is the thermodynamic modeling supported hypothesis that, in the isochoric frozen solution the extracellular osmolality is comparable to the cell intracellular osmolality. Therefore, cells in the isochoric frozen organism do not dehydrate, and the tissue maintains its morphological integrity. Comparing the histology of: a) fresh fish white muscle, b) fresh muscle frozen to -5 °C in an isobaric system and c) fresh muscle frozen to -5 °C I in an isochoric system, we find convincing evidence of the mechanism of cell dehydration during isobaric freezing. In contrast, the muscle tissue frozen to -5 °C in an isochoric system appears morphologically identical to fresh tissue, with no evidence of dehydration. This is the first experimental evidence in support of the hypothesis that in isochoric freezing there is no cellular dehydration and therefore the morphology of the frozen tissue remains intact.

  19. The role of antioxidant system in freezing acclimation-induced freezing resistance of Populus suaveolens cuttings

    Institute of Scientific and Technical Information of China (English)

    Luo Lei; Lin Shan-zhi; Zheng Hui-quan; Lei Yang; Zhang Qian; Zhang Zhi-yi

    2007-01-01

    We investigated the changes in the contents of H2O2, malonaldehyde (MDA) and endogenous antioxidants, the activities of protective enzymes and some critical enzymes involved in the ascorbate-glutathione (ASA-GSH) cycle as well as freezing resistance(expressed as LT50) and correlations mentioned above, in detail using Populus suaveolens cuttings. The purpose was to explore the physiological mechanism of the enhancement of freezing resistance induced by freezing acclimation at -20℃, and to elucidate the physiological mechanisms by which trees adapt to freezing. The results showed that freezing acclimation enhanced the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), monodehydroascorbate reductase (MDAR), ascorbate peroxidase(APX), dehydroascorbate reductase (DHAR) and glutathione reductase (GR). And it increased the contents of reduced ascorbate(ASA), reduced glutathione (GSH), dehydroascorbate (DHA) and oxidized glutathione (GSSG). However, H2O2 and MDA contents and LT50 of cuttings were decreased. LT50 in cuttings was found to be closely correlated to the levels of SOD, POD, CAT, APX,DHAR, MDAR, GR, H2O2, MDA, ASA, GSH, DHA and GSSG during freezing acclimation. This suggested that the enhancement of freezing resistance of cuttings induced by freezing acclimation may relate to the distinct increase for the levels of SOD, POD, CAT,APX, DHAR, MDAR,GR,ASA, GSH, DHA, and GSSG. In addition, the observed levels of APX, DHAR, MDAR, GR, ASA, DHA,GSH and GSSG were higher than those of SOD, POD and CAT during freezing acclimation. It indicated that a higher capacity of the ASA-GSH cycle is required for H2O2 detoxification, and growth and development of cuttings. Based on the obtained results, it can be concluded that the ASA-GSH cycle plays an important role in enhancement of freezing resistance of P. suaveolens cuttings during freezing acclimation.

  20. A new freeze casting technique for ceramics

    Science.gov (United States)

    Araki, Kiyoshi

    A new freeze casting technique for ceramics capable of manufacturing near room temperature with a sublimable vehicle has been developed in order to eliminate expensive processes under extremely cold temperatures in the conventional freeze casting. Fluid concentrated slurries of Al2O 3 powder in molten camphene (C10H16) were successfully prepared at 55°C with a small amount of a dispersant. These slurries were quickly solidified (frozen) at room temperature to yield a rigid solid green body, where the frozen camphene was easily removed by sublimation (freeze-drying) with negligible shrinkage. Sintering was successfully conducted without any special binder burnout process to yield dense sintered bodies (over 98% T.D). An organic alloy with a eutectic composition in the naphthalene (C 10H8)-camphor (C10H16O) binary system with a eutectic temperature of 31°C was also found to be a successful vehicle for the new ceramic freeze casting. The fabrication processes are almost the same as those with camphene. It was found that vehicles with off-eutectic compositions resulted in large voids in the sintered body due to the ceramic particle rejection by pro-eutectic crystals during freezing. At the eutectic composition, fine lamellar microstructure in the solidified vehicle inhibits the particle rejection. The proposed advantages of the new freeze casting technique with a sublimable vehicle include; (1) elimination of extremely cold temperatures used in conventional freeze casting; (2) elimination of troublesome binder burnout process; and (3) fast manufacturing cycle due to quick solidification. Porous ceramic bodies with unique interconnected pore channels were fabricated by the new freeze casting with lower solid content. The unique channels surrounded by fully dense walls have nearly circular cross-sections unlike conventional aqueous freeze casting. The porosity and the channel diameters are controllable by the solid content in the slurry. The unique channels are

  1. Temperatura letal de diferentes plantas frutíferas tropicais Freezing points of various tropical fruits

    Directory of Open Access Journals (Sweden)

    Paulo Cesar Sentelhas

    1996-01-01

    Full Text Available Com o objetivo de conhecer melhor o efeito das baixas temperaturas sobre as frutíferas de clima tropical e possibilitar o desenvolvimento de novas variedades, mais tolerantes, simularam-se geadas em câmaras frigoríficas para a determinação da temperatura letal de diferentes plantas frutíferas tropicais. Os resultados permitiram classificar as espécies em três grupos: Grupo I - moderada tolerância (-4°C: condessa (Annona reticulata; goiaba (Psidium guajava; acerola (Malpighia glabra e abacate (Persea americana var. Geada; Grupo II - média tolerância (-5°C: conde (A. squamosa; araticum-mirim (Rollinea spp.; anona-do-brejo (A. glabra; falsa-gravioleira (A. montana; araticum-de-folha-miúda (R. ermaginata e maracujá-amarelo (Passiflora edulis f. flavicarpa; Grupo III - acentuada tolerância (-6°C: cherimóia (A. cherimola.The effect of low temperature on tropical fruits was studied in order to guide future developments of frost resistant varieties. Simulations of frost were done in a freezing chamber to determine the freezing points of various fruit plants. On the basis of the results the studied species can be classified into three groups according to their tolerance to low temperatures: Group I - little tolerance (-4°C: Annona reticulata; Psidium guajava; Malpighia glabra and Persea americana (var. Geada; Group II - medium tolerance (-5°C: A. squamosa; Rollinea spp.; A. glabra; A. montana; R. ermaginata and Passiflora edulis f. flavicarpa; Group III - high tolerance (-6°C: A. cherimola.

  2. UDP-glucosyltransferase71c5, a major glucosyltransferase, mediates abscisic acid homeostasis in Arabidopsis.

    Science.gov (United States)

    Liu, Zhen; Yan, Jin-Ping; Li, De-Kuan; Luo, Qin; Yan, Qiujie; Liu, Zhi-Bin; Ye, Li-Ming; Wang, Jian-Mei; Li, Xu-Feng; Yang, Yi

    2015-04-01

    Abscisic acid (ABA) plays a key role in plant growth and development. The effect of ABA in plants mainly depends on its concentration, which is determined by a balance between biosynthesis and catabolism of ABA. In this study, we characterize a unique UDP-glucosyltransferase (UGT), UGT71C5, which plays an important role in ABA homeostasis by glucosylating ABA to abscisic acid -: glucose ester (GE) in Arabidopsis (Arabidopsis thaliana). Biochemical analyses show that UGT71C5 glucosylates ABA in vitro and in vivo. Mutation of UGT71C5 and down-expression of UGT71C5 in Arabidopsis cause delay in seed germination and enhanced drought tolerance. In contrast, overexpression of UGT71C5 accelerates seed germination and reduces drought tolerance. Determination of the content of ABA and ABA-GE in Arabidopsis revealed that mutation in UGT71C5 and down-expression of UGT71C5 resulted in increased level of ABA and reduced level of ABA-GE, whereas overexpression of UGT71C5 resulted in reduced level of ABA and increased level of ABA-GE. Furthermore, altered levels of ABA in plants lead to changes in transcript abundance of ABA-responsive genes, correlating with the concentration of ABA regulated by UGT71C5 in Arabidopsis. Our work shows that UGT71C5 plays a major role in ABA glucosylation for ABA homeostasis.

  3. An Arabidopsis callose synthase

    DEFF Research Database (Denmark)

    Ostergaard, Lars; Petersen, Morten; Mattsson, Ole

    2002-01-01

    in the Arabidopsis mpk4 mutant which exhibits systemic acquired resistance (SAR), elevated beta-1,3-glucan synthase activity, and increased callose levels. In addition, AtGsl5 is a likely target of salicylic acid (SA)-dependent SAR, since AtGsl5 mRNA accumulation is induced by SA in wild-type plants, while...... expression of the nahG salicylate hydroxylase reduces AtGsl5 mRNA levels in the mpk4 mutant. These results indicate that AtGsl5 is likely involved in callose synthesis in flowering tissues and in the mpk4 mutant....

  4. Adverse effect of urease on salt stress during seed germination in Arabidopsis thaliana.

    Science.gov (United States)

    Bu, Yuanyuan; Kou, Jing; Sun, Bo; Takano, Testuo; Liu, Shenkui

    2015-05-22

    Seed germination is a critical stage in the development of crops that grow in saline soils. We noticed that seeds of an Arabidopsis urease mutant have significantly increased salt stress tolerance. To understand why, we treated the wild type (WT) with a urease inhibitor and found that its salt stress tolerance was also improved. We hypothesized that urease acting on urea generates NH₄⁺, which probably exacerbates salt stress. As expected, the urease inhibitor significantly decreased the NH₄⁺ level in WT seeds. These findings suggest that blocking urease activity improves salt tolerance during seed germination by lowering the concentration of NH₄⁺.

  5. Saccharomyces cerevisiae glycerol/H+ symporter Stl1p is essential for cold/near-freeze and freeze stress adaptation. A simple recipe with high biotechnological potential is given

    Directory of Open Access Journals (Sweden)

    Ferreira Célia

    2010-11-01

    Full Text Available Abstract Background Freezing is an increasingly important means of preservation and storage of microbial strains used for many types of industrial applications including food processing. However, the yeast mechanisms of tolerance and sensitivity to freeze or near-freeze stress are still poorly understood. More knowledge on this regard would improve their biotechnological potential. Glycerol, in particular intracellular glycerol, has been assigned as a cryoprotectant, also important for cold/near-freeze stress adaptation. The S. cerevisiae glycerol active transporter Stl1p plays an important role on the fast accumulation of glycerol. This gene is expressed under gluconeogenic conditions, under osmotic shock and stress, as well as under high temperatures. Results We found that cells grown on STL1 induction medium (YPGE and subjected to cold/near-freeze stress, displayed an extremely high expression of this gene, also visible at glycerol/H+ symporter activity level. Under the same conditions, the strains harbouring this transporter accumulated more than 400 mM glycerol, whereas the glycerol/H+ symporter mutant presented less than 1 mM. Consistently, the strains able to accumulate glycerol survive 25-50% more than the stl1Δ mutant. Conclusions In this work, we report the contribution of the glycerol/H+ symporter Stl1p for the accumulation and maintenance of glycerol intracellular levels, and consequently cell survival at cold/near-freeze and freeze temperatures. These findings have a high biotechnological impact, as they show that any S. cerevisiae strain already in use can become more resistant to cold/freeze-thaw stress just by simply adding glycerol to the broth. The combination of low temperatures with extracellular glycerol will induce the transporter Stl1p. This solution avoids the use of transgenic strains, in particular in food industry.

  6. An Investigation of Freezing of Supercooled Water on Anti-Freeze Protein Modified Surfaces

    Institute of Scientific and Technical Information of China (English)

    Thibaut V J Charpentier; Anne Neville; Paul Millner; Rob Hewson; Ardian Morina

    2013-01-01

    This work investigates how functionalization ofaluminium surfaces with natural type Ⅲ Anti-Freeze Protein (AFP) affects the mechanism of heterogeneous ice nucleation.First the bulk ice nucleation properties of distilled water and aqueous solution of AFP were evaluated by differential scanning calorimetry.Then the modified surface was characterized by Secondary Ions Mass Spectroscopy (SIMS),Fourier Transform InfraRed (FTIR) spectroscopy and contact angle measurement.Freezing experiments were then conducted in which water droplets underwent a slow controlled cooling.This study shows that compared to uncoated aluminium,the anti-freeze proteins functionalized surfaces exhibit a higher and narrower range of freezing temperature.It was found that these proteins that keep living organisms from freezing in cold environment act in the opposite way once immobilized on surfaces by promoting ice nucleation.Some suggestions regarding the mechanism of action of the observed phenomena were proposed based on the Classical Nucleation Theory (CNT).

  7. Model plant systems in salinity and drought stress proteomics studies: a perspective on Arabidopsis and Sorghum.

    Science.gov (United States)

    Ngara, R; Ndimba, B K

    2014-11-01

    More than a decade after the sequencing of its genome, Arabidopsis still stands as the epitome of a model system in plant biology. Arabidopsis proteomics has also taught us great lessons on different aspects of plant growth, development and physiology. Without doubt our understanding of basic principles of plant biology would not have been this advanced if it were not for knowledge gained using Arabidopsis as a model system. However, with the projections of global climate change and rapid population growth, it is high time we evaluate the applicability of this model system in studies aimed at understanding abiotic stress tolerance and adaptation, with a particular emphasis on maintaining yield under hot and dry environmental conditions. Because of the innate nature of sorghum's tolerance to drought and moderate tolerance to salinity stresses, we believe sorghum is the next logical model system in such studies amongst cereals. In this acute view, we highlight the importance of Arabidopsis as a model system, briefly discuss its potential limitations in drought and salt stress studies, and present our views on the potential usefulness of sorghum as a model system for cereals in drought and salinity stress proteomic studies.

  8. Freeze-drying of lactic acid bacteria.

    Science.gov (United States)

    Fonseca, Fernanda; Cenard, Stéphanie; Passot, Stéphanie

    2015-01-01

    Lactic acid bacteria are of great importance for the food and biotechnology industry. They are widely used as starters for manufacturing food (e.g., yogurt, cheese, fermented meats, and vegetables) and probiotic products, as well as for green chemistry applications. Freeze-drying or lyophilization is a convenient method for preservation of bacteria. By reducing water activity to values below 0.2, it allows long-term storage and low-cost distribution at suprazero temperatures, while minimizing losses in viability and functionality. Stabilization of bacteria via freeze-drying starts with the addition of a protectant solution to the bacterial suspension. Freeze-drying includes three steps, namely, (1) freezing of the concentrated and protected cell suspension, (2) primary drying to remove ice by sublimation, and (3) secondary drying to remove unfrozen water by desorption. In this chapter we describe a method for freeze-drying of lactic acid bacteria at a pilot scale, thus allowing control of the process parameters for maximal survival and functionality recovery.

  9. Female Fertility: Is it Safe to "Freeze?"

    Directory of Open Access Journals (Sweden)

    Lu Zhang

    2015-01-01

    Full Text Available Objective: To evaluate the safety and risk of cryopreservation in female fertility preservation. Data sources: The data analyzed in this review were the English articles from 1980 to 2013 from journal databases, primarily PubMed and Google scholar. The criteria used in the literature search show as following: (1 human; embryo; cryopreservation/freezing/vitrification, (2 human; oocyte/immature oocyte; cryopreservation/ freezing/vitrification, (3 human; ovarian tissue transplantation; cryopreservation/freezing/vitrification, (4 human; aneuploidy/DNA damage/epigenetic; cryopreservation/freezing/vitrification, and (5 human; fertility preservation; maternal age. Study selection: The risk ratios based on survival rate, maturation rate, fertilization rate, cleavage rate, implantation rate, pregnancy rate, and clinical risk rate were acquired from relevant meta-analysis studies. These studies included randomized controlled trials or studies with one of the primary outcome measures covering cryopreservation of human mature oocytes, embryos, and ovarian tissues within the last 7 years (from 2006 to 2013, since the pregnancy rates of oocyte vitrification were significantly increased due to the improved techniques. The data involving immature oocyte cryopreservation obtained from individual studies was also reviewed by the authors. Results: Vitrifications of mature oocytes and embryos obtained better clinical outcomes and did not increase the risks of DNA damage, spindle configuration, embryonic aneuploidy, and genomic imprinting as compared with fresh and slow-freezing procedures, respectively. Conclusions: Both embryo and oocyte vitrifications are safe applications in female fertility preservation.

  10. NFXL2 modifies cuticle properties in Arabidopsis.

    Science.gov (United States)

    Lisso, Janina; Schröder, Florian; Schippers, Jos H M; Müssig, Carsten

    2012-05-01

    Loss of the Arabidopsis NFX1-LIKE2 (NFXL2) gene (At5g05660) results in elevated ABA levels, elevated hydrogen peroxide levels, reduced stomatal aperture, and enhanced drought stress tolerance. Introduction of the NFXL2-78 isoform into the nfxl2-1 mutant is largely sufficient for complementation of the phenotype. We show here that cuticular properties are altered in the nfxl2-1 mutant. The NFXL2-78 protein binds to the SHINE1 (SHN1), SHN2, SHN3, and BODYGUARD1 (BDG1) promoters and mediates weaker expression of these genes. The SHN AP2 domain transcription factors influence cuticle properties. Stronger SHN1, SHN2, and SHN3 expression in the nfxl2-1 mutant may cause altered cuticle properties including reduced stomatal density, and partly explain the enhanced drought stress tolerance. The BDG1 protein also controls cuticle development and is essential for osmotic stress regulation of ABA biosynthesis. Stronger BDG1 expression in nfxl2-1 plants may allow elevated ABA accumulation under drought stress. We conclude that the NFXL2-78 protein is part of a regulatory network that integrates the biosynthesis and action of ABA, ROS, and cuticle components.

  11. Freeze substitution in 3 hours or less.

    Science.gov (United States)

    McDonald, K L; Webb, R I

    2011-09-01

    Freeze substitution is a process for low temperature dehydration and fixation of rapidly frozen cells that usually takes days to complete. New methods for freeze substitution have been developed that require only basic laboratory tools: a platform shaker, liquid nitrogen, a metal block with holes for cryotubes and an insulated container such as an ice bucket. With this equipment, excellent freeze substitution results can be obtained in as little as 90 min for cells of small volume such as bacteria and tissue culture cells. For cells of greater volume or that have significant diffusion barriers such as cuticles or thick cell walls, one can extend the time to 3 h or more with dry ice. The 3-h method works well for all manner of specimens, including plants and Caenorhabditis elegans as well as smaller samples. Here, we present the basics of the techniques and some results from Nicotiana leaves, C. elegans adult worms, Escherichia coli and baby hamster kidney tissue culture cells.

  12. Heat transfer coefficient of cryotop during freezing.

    Science.gov (United States)

    Li, W J; Zhou, X L; Wang, H S; Liu, B L; Dai, J J

    2013-01-01

    Cryotop is an efficient vitrification method for cryopreservation of oocytes. It has been widely used owing to its simple operation and high freezing rate. Recently, the heat transfer performance of cryotop was studied by numerical simulation in several studies. However, the range of heat transfer coefficient in the simulation is uncertain. In this study, the heat transfer coefficient for cryotop during freezing process was analyzed. The cooling rates of 40 percent ethylene glycol (EG) droplet in cryotop during freezing were measured by ultra-fast measurement system and calculated by numerical simulation at different value of heat transfer coefficient. Compared with the results obtained by two methods, the range of the heat transfer coefficient necessary for the numerical simulation of cryotop was determined, which is between 9000 W/(m(2)·K) and 10000 W/(m (2)·K).

  13. Freezing precipitation in Russia and the Ukraine

    Directory of Open Access Journals (Sweden)

    A. A. Zavyalova

    2007-04-01

    Full Text Available Conditions for freezing precipitation (FP, including freezing rain (FR and freezing drizzle (FZ for 8 airports in Russia and 4 in the Ukraine are studied on the basis of 10 to 20-year series of surface observations, radiosonde and objective analysis data. Statistical characteristics are presented of the FP episode durations and of occurrence frequency dependences on surface air temperature, wind direction and speed and cloud base height. From the radiosonde data, it is found that the "classical mechanism" of FP generation (for which, stratification of "warm nose" type in the cloud layer is necessary is not frequent: most of FP cases are associated with "all cold" conditions in the lower 3-km layer, that is, with negative temperatures in and below the clouds.

  14. Building the Method to Determine the Rate of Freezing Water in Penaeus monodon of the Freezing Process

    Directory of Open Access Journals (Sweden)

    Nguyen Tan Dzung

    2012-10-01

    Full Text Available The method of determination the rate of freezing water in Penaeus monodon of freezing process was established on base the equation of energy balance in warming up process Penaeus monodon after freezing to determine specific heat of Penaeus monodon. The result obtained was built the mathematical model (19 to determine the rate of freezing water according to the freezing temperature of Penaeus monodon. The results indicated that when water was completely frozen (ω = 1 or 100%, the optimal freezing temperature of Penaeus monodon was-22.00°C.

  15. Cold tolerance and cold hardening strategy of the Japanese pine sawyer Monochamus alternatus (Coleoptera: Cerambycidae)

    Institute of Scientific and Technical Information of China (English)

    Jing Tian; Shu-Guang Hao; Wei-Na Kong; Rui-Yan Ma; Le Kang

    2008-01-01

    The Japanese pine sawyer, Monochamus alternatus, is an important pine forest pest and vector transmitting the pine wilt nematode that causes pine wilt disease. Low temperatures in autumn, winter and spring often differentially affect mortality of M.alternatus larvae. In this paper, we mainly compared the differences of mortality and cold hardening of larvae from different seasons, based on supercooling point (SCP) and cumulative probability of individuals freezing (CPIF). The cold hardening of the larvae from autumn, winter and spring seasons were largely different. Correlations between mortality and CPIF of autumn and spring larvae were highest on day 1/4, and gradually decreased with prolonged exposure duration. This beetle's death mainly resulted from freezing in short exposure duration. However, the correlation between mortality and CPIF of winter larvae increased gradually with the prolonged exposure duration. Death did not mainly result from freezing in long exposure duration. Autumn larvae are more susceptible and adaptable than winter and spring larvae. Winter larvae have a slight freeze-tolerance trend. Our research showed that M. alternatus came into complex cold-hardening strategies under natural selection. Freeze avoidance is the primary strategy; with prolonged exposure duration to above SCP or < 0℃, chill tolerance is more important; this is followed by freeze tolerance during harsh winters.

  16. Cold tolerance abilities of two entomopathogenic nematodes, Steinernema feltiae and Heterorhabditis bacteriophora.

    Science.gov (United States)

    Ali, Farman; Wharton, David A

    2013-02-01

    Entomopathogenic nematodes are effective biological control agents against insect pests but their commercial application is restricted by their limited shelf life. This study applies our knowledge of the cold tolerance of nematodes to this problem and investigates further the cold tolerance mechanisms of Steinernema feltiae and Heterorhabditis bacteriophora infective juveniles. When frozen using a fast freezing regime these nematodes are moderately freezing tolerant, with a lower lethal temperature of -5°C. Survival is significantly enhanced by slow freezing overnight (at -1°C), with a decrease in the lower lethal temperature to -14°C. This may indicate that these nematodes are capable of cryoprotective dehydration. Acclimation at 5°C further enhanced freezing survival in S. feltiae but only by a small amount. Nematodes that had survived freezing to -13°C retained their pathogenicity to an insect host. Rapid cold hardening or exposure to a cold shock had no significant effect on freezing survival. The further development of methods based on cryoprotective dehydration may result in a method for the commercial storage of these nematodes.

  17. Reference: 774 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available an essential gene, the disruption of which causes embryonic lethality. Plants carrying a hypomorphic smg7 mu...e progression from anaphase to telophase in the second meiotic division in Arabidopsis. Arabidopsis SMG7 is

  18. Reference: 398 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available plays attenuated chloroplast movements under intermediate and high light intensitie...hese movements. In this work, we describe plastid movement impaired 2 (pmi2), a mutant in Arabidopsis (Arabidopsis thaliana) that dis

  19. Reference: 173 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available mical approaches to elucidate the action mechanisms of sirtinol in Arabidopsis. A...tic and chemical analyses of the action mechanisms of sirtinol in Arabidopsis. 8 3129-34 15710899 2005 Feb P

  20. Reference: 718 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available displayed a moderate but significant decrease in germination in the presence of D...NA damage. This report links Ubc13-Uev with functions in DNA damage response in Arabidopsis. Arabidopsis UEV

  1. Arabidopsis CDS blastp result: AK068856 [KOME

    Lifescience Database Archive (English)

    Full Text Available eme oxygenase (HY1) [Arabidopsis thaliana] GI:4877362, heme oxygenase 1 [Arabidopsis thaliana] GI:4530591 GB:AF132475; annotation upd...ated per Seth J. Davis at University of Wisconsin-Madison 3e-90 ...

  2. Arabidopsis CDS blastp result: AK104955 [KOME

    Lifescience Database Archive (English)

    Full Text Available B:AF132475; annotation updated per Seth J. Davis at University of Wisconsin-Madison 3e-90 ... ...heme oxygenase (HY1) [Arabidopsis thaliana] GI:4877362, heme oxygenase 1 [Arabidopsis thaliana] GI:4530591 G

  3. Reference: 110 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available on process. Our study shows that an Arabidopsis SNM protein, although structurally closer to the SNM1/PSO2 members, shares some prope...rties with ARTEMIS but also has novel characteristics. Arabidopsis plants defective

  4. Scaling-Up Eutectic Freeze Crystallization

    NARCIS (Netherlands)

    Genceli, F.E.

    2008-01-01

    A novel crystallization technology, Eutectic Freeze Crystallization (EFC) has been investigated and further developed in this thesis work. EFC operates around the eutectic temperature and composition of aqueous solutions and can be used for recovery of (valuable) dissolved salts (and/or or acids) an

  5. Asset Freezing: Smart Sanction or Criminal Charge?

    NARCIS (Netherlands)

    Broek, Melissa van den; Hazelhorst, Monique; Zanger, Wouter de

    2011-01-01

    In this article the question is asked whether asset freezing can be qualified as a criminal charge within the meaning of Article6 ECHR and if yes, what effects this qualification may have on the legislative framework on so called smart sanctions. Byanalysing Community and EU law and case law of the

  6. Freeze-thaw induced gelation of alginates.

    Science.gov (United States)

    Zhao, Ying; Shen, Wei; Chen, Zhigang; Wu, Tao

    2016-09-01

    Adding divalent ions or lowering pH below the pKa values of alginate monomers are common ways in preparing alginate gels. Herein a new way of preparing alginate gels using freeze-thaw technique is described. Solvent crystallization during freezing drove the polymers to associate into certain structures that became the junction zones of hydrogels after thawing. It enabled the preparation of alginate gels at pH 4.0 and 3.5, two pH at which the gel could not be formed previously. At pH 3.0 where alginate gel could be formed initially, applying freeze-thaw treatment increased the gel storage modulus almost 100 times. The formation of hydrogels and the resulting gel properties, such as dynamic moduli and gel syneresis were influenced by the pH values, number of freeze-thaw cycles, alginate concentrations, and ionic strengths. The obtained hydrogels were soft and demonstrated a melting behavior upon storage, which may find novel applications in the biomedical industry.

  7. Liquid carbon: structure near the freezing line

    NARCIS (Netherlands)

    Ghiringhelli, L.M.; Los, J.H.; Meijer, E.J.; Fasolino, A.; Frenkel, D.

    2005-01-01

    We present a detailed analysis of the structure of liquid carbon near the freezing line. The results are obtained by molecular simulation using a recently developed state-of-the-art bond order potential. We find that along the melting line the liquid is predominantly threefold coordinated up to pres

  8. Anomalous freezing behavior of nanoscale liposomes

    DEFF Research Database (Denmark)

    Spangler, E. J.; Kumar, P. B. S.; Laradji, M.

    2012-01-01

    The effect of the finite size of one-component liposomes on their phase behavior is investigated via simulations of an implicit-solvent model of self-assembled lipid bilayers. We found that the high curvature of nanoscale liposomes has a significant effect on their freezing behavior. While...

  9. Nucleation Pathways For Freezing Of Two Grades Of Zirconium

    Science.gov (United States)

    Rhim, Won-Kyu; Rulison, Aaron; Bayuzick, Robert; Hofmeister, William; Morton, Craig

    1996-01-01

    Report discusses classical nucleation theory of freezing and describes experimental study of nucleation mechanisms that predominate during freezing of spherical specimens of initially molten zirconium levitated electrostatically in vacuum.

  10. Freezing characteristics and texture variation after freezing and thawing of four fruit types

    Directory of Open Access Journals (Sweden)

    Arpassorn Sirijariyawat

    2012-11-01

    Full Text Available One major problem with frozen fruits is a loss of texture. Therefore this study investigated the effects of the freezingprocess on the freezing profiles, texture, and drip loss of apple, mango, cantaloupe, and pineapple fruit samples. All frozenthawedfruits varied in these three properties because of diversity in the fresh fruits. Mango had the highest total solublesolids content and the lowest freezing point, whereas pineapple showed the highest freezing rate. The highest firmness andcrunchy texture were found in fresh apple, and these properties were absent in the other fresh fruits. The firmness of allfrozen fruits significantly decreased by different percentages as compared to those of the fresh fruits. The drip loss of eachfruit type was also significantly different with apple samples having the highest firmness decrease and drip loss. This studyshows that freezing characteristics and frozen fruit properties depend on type of fruit.

  11. Female Fertility: Is it Safe to "Freeze?"

    Institute of Scientific and Technical Information of China (English)

    Lu Zhang; Li-Ying Yan; Xu Zhi; Jie Yan; Jie Qiao

    2015-01-01

    Objective:To evaluate the safety and risk of cryopreservation in female fertility preservation.Data sources:The data analyzed in this review were the English articles from 1980 to 2013 from journal databases,primarily PubMed and Google scholar.The criteria used in the literature search show as following:(1) human; embryo; cryopreservation/freezing/vitrification,(2) human; oocyte/immature oocyte; cryopreservation/freezing/vitrification,(3) human; ovarian tissue transplantation; cryopreservation/ freezing/vitrification,(4) human; aneuploidy/DNA damage/epigenetic; cryopreservation/freezing/vitrification,and (5) human; fertility preservation; maternal age.Study selection:The risk ratios based on survival rate,maturation rate,fertilization rate,cleavage rate,implantation rate,pregnancy rate,and clinical risk rate were acquired from relevant meta-analysis studies.These studies included randomized controlled trials or studies with one of the primary outcome measures covering cryopreservation of human mature oocytes,embryos,and ovarian tissues within the last 7 years (from 2006 to 2013,since the pregnancy rates of oocyte vitrification were significantly increased due to the improved techniques).The data involving immature oocyte cryopreservation obtained from individual studies was also reviewed by the authors.Results:Vitrifications of mature oocytes and embryos obtained better clinical outcomes and did not increase the risks of DNA damage,spindle configuration,embryonic aneuploidy,and genomic imprinting as compared with fresh and slow-freezing procedures,respectively.Conclusions:Both embryo and oocyte vitrifications are safe applications in female fertility preservation.

  12. COMPREHENSIVE DESIGN METHOD OF FREEZE WALL AND ITS APPLICATION

    Institute of Scientific and Technical Information of China (English)

    CHENXiangsheng

    1995-01-01

    Artificially ground freezing (AGF) is one of the main methods to establish temporary support for shaft sinking in unstable water bearing strata. Domke(1915) formula based on frozen soil strength has widely been used for designing freeze wall thickness. However, it can not ensure the stability of freeze wall, nor guarantee the safety of shaft construction as frozen depth increase in unstable water bearing strata. F.A.Auld (1985, 1988) presented a design method of freeze wall, which is on the basis of strength and stability, together with deformation of freeze wall.He combined deformation of freeze wall, lining and deformation of freeze tube to set up a comprehensive design method for freeze wall. This paper, according to the practice in China, describes a comprehensive design method for deep freeze wall, considering influence of excavation rate of advance, unsupported length of freeze wall and the sump state on inward deformation of freeze wall, and the allowable pipe deformation caused by inward deformation of freeze wall. Finally, successful application of this method to the large scale coal mine-Jining No.2 Mine in Shandong Province of China, is presented.It saved much investment compared with F.A.Auld's design for the same mine on behalf of Shell Coal International.

  13. 7 CFR 58.620 - Freezing and packaging rooms.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Freezing and packaging rooms. 58.620 Section 58.620 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....620 Freezing and packaging rooms. The rooms used for freezing and packaging frozen desserts shall...

  14. Objective video quality assessment method for freeze distortion based on freeze aggregation

    Science.gov (United States)

    Watanabe, Keishiro; Okamoto, Jun; Kurita, Takaaki

    2006-01-01

    With the development of the broadband network, video communications such as videophone, video distribution, and IPTV services are beginning to become common. In order to provide these services appropriately, we must manage them based on subjective video quality, in addition to designing a network system based on it. Currently, subjective quality assessment is the main method used to quantify video quality. However, it is time-consuming and expensive. Therefore, we need an objective quality assessment technology that can estimate video quality from video characteristics effectively. Video degradation can be categorized into two types: spatial and temporal. Objective quality assessment methods for spatial degradation have been studied extensively, but methods for temporal degradation have hardly been examined even though it occurs frequently due to network degradation and has a large impact on subjective quality. In this paper, we propose an objective quality assessment method for temporal degradation. Our approach is to aggregate multiple freeze distortions into an equivalent freeze distortion and then derive the objective video quality from the equivalent freeze distortion. Specifically, our method considers the total length of all freeze distortions in a video sequence as the length of the equivalent single freeze distortion. In addition, we propose a method using the perceptual characteristics of short freeze distortions. We verified that our method can estimate the objective video quality well within the deviation of subjective video quality.

  15. Freezing temperatures as a limit to forest recruitment above tropical Andean treelines.

    Science.gov (United States)

    Rehm, Evan M; Feeley, Kenneth J

    2015-07-01

    The elevation of altitudinal treelines is generally believed to occur where low mean temperatures during the growing season limit growth and prevent trees from establishing at higher elevations. Accordingly, treelines should move upslope with increasing global temperatures. Contrary to this prediction, tropical treelines have remained stable over the past several decades despite increasing mean temperatures. The observed stability of tropical treelines, coupled with the drastically different temperature profiles between temperate and tropical treelines, suggests that using mean measures of temperature to predict tropical treeline movements during climate change may be overly simplistic. We hypothesize that frost events at tropical treelines may slow climate driven treeline movement by preventing tree recruitment beyond the established forest canopy. To assess this hypothesis, we measured freezing resistance of four canopy-forming treeline species (Weinmannia fagaroides, Polylepis pauta, Clethra cuneata, and Gynoxys nitida) at two life stages (juvenile and adult) and during two seasons (warm-wet and cold-dry). Freezing resistances were then compared to microclimatic data to determine if freezing events in the grassland matrix above treeline are too harsh for these forest species. Freezing resistance varied among species and life stages from -5.7 degrees C for juveniles of P. pauta to -11.1 degrees C for juveniles of W. fagaroides. Over a four-year period, the lowest temperatures recorded at 10 cm above ground level in the grasslands above treeline and at treeline itself were -8.9 degrees C and -6.8 degrees C, respectively. Juveniles maintained freezing resistances similar to adults during the coldest parts of the year and ontogenetic differences in freezing resistance were only present during the warm season when temperatures did not represent a significant threat to active plant tissue. These findings support the hypothesis that rare extreme freezing events at and

  16. Complex-Shaped Porous Cu Bodies Fabricated by Freeze-Casting and Vacuum Sintering

    Directory of Open Access Journals (Sweden)

    Huashen Ran

    2015-10-01

    Full Text Available Porous Cu bodies with complex shapes were fabricated by freeze-casting and vacuum sintering water-based CuO slurry. The sintered bodies showed no noticeable macroscopic defects and good shape tolerance. The interconnected pore tunnels were observed by electronic microscopy. The pore size became smaller and the porosity and volume shrinkage of sintered porous bodies decreased with the increase of solid content in the slurry. XRD results showed the CuO was fully decomposed by vacuum sintering into Cu without any second phases. This new fabrication method may be especially economical when small quantities of porous parts are required.

  17. HAL1 mediate salt adaptation in Arabidopsis thaliana

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The yeast HAL1 gene was introduced into Arabidopsis thaliana by Agrobacterium tumefaciens-mediated transformation with vacuum infiltration under the control of CaMV 35S promoter.Thirty-three individual kanamycin resistant plants were obtained from 75,000 seeds.Southern blotting analysis indicated that HAL1 gene had been integrated into all of the transgenic plants' genomes.The copy number of HAL1 gene in transgenic plants was mostly 1 to 3 by Southern analysis.Phenotypes of transgenic plants have no differences with wild type plants.Several samples of transformants were self-pollinated,and progenies from transformed and non-transformed plants(controls)were evaluated for salt tolerance and gene expression.Measurement of concentrations of intracellular K+ and Na+ showed that transgenic lines were able to retain less Na+ than that of the control under salt stress.Results from different tests indicated the expression of HAL1 gene promotes a higher level of salt tolerance in vivo in the transgenic Arabidopsis plants.

  18. The freezing and supercooling of garlic (Allium sativum L.)

    Energy Technology Data Exchange (ETDEWEB)

    James, Christian; Seignemartin, Violaine; James, Stephen J. [Food Refrigeration and Process Engineering Research Centre (FRPERC), University of Bristol, Churchill Building, Langford, Bristol BS40 5DU (United Kingdom)

    2009-03-15

    This work shows that peeled garlic cloves demonstrate significant supercooling during freezing under standard conditions and can be stored at temperatures well below their freezing point (-2.7 C) without freezing. The nucleation point or 'metastable limit temperature' (the point at which ice crystal nucleation is initiated) of peeled garlic cloves was found to be between -7.7 and -14.6 C. Peeled garlic cloves were stored under static air conditions at temperatures between -6 and -9 C for up to 69 h without freezing, and unpeeled whole garlic bulbs and cloves were stored for 1 week at -6 C without freezing. (author)

  19. Arabidopsis thaliana peroxidase N

    DEFF Research Database (Denmark)

    Mirza, Osman Asghar; Henriksen, A; Ostergaard, L

    2000-01-01

    The structure of the neutral peroxidase from Arabidopsis thaliana (ATP N) has been determined to a resolution of 1.9 A and a free R value of 20.5%. ATP N has the expected characteristic fold of the class III peroxidases, with a C(alpha) r.m.s.d. of 0.82 A when compared with horseradish peroxidase C...... (HRP C). HRP C is 54% identical to ATP N in sequence. When the structures of four class III plant peroxidases are superimposed, the regions with structural differences are non-randomly distributed; all are located in one half of the molecule. The architecture of the haem pocket of ATP N is very similar...... to that of HRP C, in agreement with the low small-molecule substrate specificity of all class III peroxidases. The structure of ATP N suggests that the pH dependence of the substrate turnover will differ from that of HRP C owing to differences in polarity of the residues in the substrate-access channel. Since...

  20. Chromosomal proteins of Arabidopsis thaliana.

    Science.gov (United States)

    Moehs, C P; McElwain, E F; Spiker, S

    1988-07-01

    In plants with large genomes, each of the classes of the histones (H1, H2A, H2B, H3 and H4) are not unique polypeptides, but rather families of closely related proteins that are called histone variants. The small genome and preponderance of single-copy DNA in Arabidopsis thaliana has led us to ask if this plant has such families of histone variants. We have thus isolated histones from Arabidopsis and analyzed them on four polyacrylamide gel electrophoretic systems: an SDS system; an acetic acid-urea system; a Triton transverse gradient system; and a two-dimensional system combining SDS and Triton-acetic acid-urea systems. This approach has allowed us to identify all four of the nucleosomal core histones in Arabidopsis and to establish the existence of a set of H2A and H2B variants. Arabidopsis has at least four H2A variants and three H2B variants of distinct molecular weights as assessed by electrophoretic mobility on SDS-polyacrylamide gels. Thus, Arabidopsis displays a diversity in these histones similar to the diversity displayed by plants with larger genomes such as wheat.The high mobility group (HMG) non-histone chromatin proteins have attracted considerable attention because of the evidence implicating them as structural proteins of transcriptionally active chromatin. We have isolated a group of non-histone chromatin proteins from Arabidopsis that meet the operational criteria to be classed as HMG proteins and that cross-react with antisera to HMG proteins of wheat.

  1. Volume versus surface nucleation in freezing aerosols

    Science.gov (United States)

    Sigurbjörnsson, Ómar F.; Signorell, Ruth

    2008-05-01

    The present study puts an end to the ongoing controversy regarding volume versus surface nucleation in freezing aerosols: Our study on nanosized aerosol particles demonstrates that current state of the art measurements of droplet ensembles cannot distinguish between the two mechanisms. The reasons are inherent experimental uncertainties as well as approximations used to analyze the kinetics. The combination of both can lead to uncertainties in the rate constants of two orders of magnitude, with important consequences for the modeling of atmospheric processes.

  2. [Equipment for spray-freezing in ophthalmology].

    Science.gov (United States)

    Anders, M; Matthes, R

    1991-05-01

    The authors discuss the theoretical background of the method of spray/freezing for destructive processes and their advantages. They demonstrate a cryo-apparatus IKG 3 for liquid nitrogen which is part of the Dresden equipment and was elaborated by the department for cryomedicine of the "Carl Gustav Carus" Academy in cooperation with the Technical University in Dresden. The apparatus produces a fine dispensable spray of the cooling mixture and permits treatment even of small tissue areas.

  3. Microarray analyses during early and later stages of the Arabidopsis/Piriformospora indica interaction

    OpenAIRE

    Khabat Vahabi; Irena Sherameti; Madhunita Bakshi; Anna Mrozinska; Anatoli Ludwig; Ralf Oelmüller

    2015-01-01

    Colonization of the roots of different plant species by Piriformospora indica results in better plant performance and biotic and abiotic stress tolerance. An increase of the biomass and seed yield is other beneficial effect of P. indica for the host plants. The interaction of P. indica with Arabidopsis thaliana roots is a unique model system to study symbiotic relationships. We describe a co-cultivation system which allows us to investigate the effects of fungal exudates on the root transcrip...

  4. Freezing of charged colloids in slit pores.

    Science.gov (United States)

    Grandner, Stefan; Klapp, Sabine H L

    2008-12-28

    Using Monte Carlo simulations in the grand canonical and isobaric ensembles we investigate freezing phenomena in a charged colloidal suspension confined to narrow slit pores. Our model involves only the macroions which interact via a Derjaguin-Landau-Verwey-Overbeek (DLVO) potential supplemented by a soft-sphere potential. We focus on DLVO parameters typical for moderately charged silica particles (with charges Z approximately 35) in solvents of low ionic strengths. The corresponding DLVO interactions are too weak to drive a (bulk) freezing transition. Nevertheless, for sufficiently small surface separations L(z) the confined systems display not only layering but also significant in-plane crystalline order at chemical potentials where the bulk system is a globally stable fluid (capillary freezing). At confinement conditions related to two-layer systems the observed in-plane structures are consistent with those detected in ground state calculations for perfect Yukawa bilayers [R. Messina and H. Lowen, Phys. Rev. Lett. 91, 146101 (2003)]. Here we additionally observe (at fixed L(z)) a compression-induced first-order phase transition from a two-layer to a three-layer system with different in-plane structure, in agreement with previous findings for pure hard spheres.

  5. Disaggregating meteorites by automated freeze thaw.

    Science.gov (United States)

    Charles, Christopher R J

    2011-06-01

    An automated freeze-thaw (AFT) instrument for disaggregating meteorites is described. Meteorite samples are immersed in 18.2 MΩ water and hermetically sealed in a clean 30 ml Teflon vial. This vial and its contents are dipped between baths of liquid nitrogen and hot water over a number of cycles by a dual-stepper motor system controlled by LabView. Uniform and periodic intervals of freezing and thawing induce multiple expansions and contractions, such that cracks propagate along natural flaws in the meteorite for a sufficient number of AFT cycles. For the CR2 chondrite NWA801, the boundaries between different phases (i.e., silicates, metal, matrix) became progressively weaker and allowed for an efficient recovery of 500 individual chondrules and chondrule fragments spanning 0.2-4.7 mm diameters after 243 AFT cycles over 103.3 h. Further FT experiments on a basalt analog showed that the time required for freezing and thawing the same number of cycles can be reduced by a factor of ∼4.

  6. Spin-freezing perspective on cuprates

    Science.gov (United States)

    Werner, Philipp; Hoshino, Shintaro; Shinaoka, Hiroshi

    2016-12-01

    The high-temperature superconducting state in cuprates appears if charge carriers are doped into a Mott-insulating parent compound. An unresolved puzzle is the unconventional nature of the normal state above the superconducting dome and its connection to the superconducting instability. At weak hole doping, a "pseudogap" metal state with signatures of time-reversal symmetry breaking is observed, which near-optimal doping changes into a "strange metal" with non-Fermi-liquid properties. Qualitatively similar phase diagrams are found in multiorbital systems, such as pnictides, where the unconventional metal states arise from a Hund-coupling-induced spin freezing. Here, we show that the relevant model for cuprates, the single-orbital Hubbard model on the square lattice, can be mapped onto an effective multiorbital problem with strong ferromagnetic Hund coupling. The spin-freezing physics of this multiorbital system explains the phenomenology of cuprates, including the pseudogap, the strange metal, and the d -wave superconducting instability. Our analysis suggests that spin/orbital freezing is the universal mechanism which controls the properties of unconventional superconductors.

  7. The influence of freezing rates on bovine pericardium tissue Freeze-drying

    Directory of Open Access Journals (Sweden)

    Camila Figueiredo Borgognoni

    2009-12-01

    Full Text Available The bovine pericardium has been used as biomaterial in developing bioprostheses. Freeze-drying is a drying process that could be used for heart valve's preservation. The maintenance of the characteristics of the biomaterial is important for a good heart valve performance. This paper describes the initial step in the development of a bovine pericardium tissue freeze-drying to be used in heart valves. Freeze-drying involves three steps: freezing, primary drying and secondary drying. The freezing step influences the ice crystal size and, consequently, the primary and secondary drying stages. The aim of this work was to investigate the influence of freezing rates on the bovine pericardium tissue freeze-drying parameters. The glass transition temperature and the structural behaviour of the lyophilized tissues were determined as also primary and secondary drying time. The slow freezing with thermal treatment presented better results than the other freeze-drying protocols.O pericárdio bovino é um material utilizado na fabricação de biopróteses. A liofilização é um método de secagem que vem sendo estudado para a conservação de válvulas cardíacas. A preservação das características do biomaterial é de fundamental importância no bom funcionamento das válvulas. Este artigo é a primeira etapa do desenvolvimento do ciclo de liofilização do pericárdio bovino. Liofilização é o processo de secagem no qual a água é removida do material congelado por sublimação e desorção da água incongelável, sob pressão reduzida. O congelamento influencia o tamanho do cristal de gelo e, consequentemente, a secagem primária e secundária. O objetivo deste estudo foi verificar a influência das taxas de congelamento nos parâmetros de liofilização do pericárdio bovino. Determinou-se a temperatura de transição vítrea e o comportamento estrutural do pericárdio bovino liofilizado. Determinou-se o tempo da secagem primária e secundária. O

  8. Response of New zealand mudsnails Potamopyrgus antipodarum to freezing and near freezing fluctuating water temperatures

    Science.gov (United States)

    Moffitt, Christine M.; James, Christopher A.

    2012-01-01

    We explored the resilience of the invasive New Zealand mudsnail Potamopyrgus antipodarum to fluctuating winter freezing and near-freezing temperature cycles in laboratory tests. Our goal was to provide data to confirm field observations of mortality and presumed mortality in stream habitats with fluctuating freezing to near-freezing temperatures. We tested individuals from 2 locations with distinctly different thermal regimes and population densities. One location had low snail densities and water temperatures with strong diel and seasonal water variation. The other location had high snail densities and nearly constant water temperatures. Groups of individuals from both locations were tested in each of 3 laboratory-created diel thermal cycles around nominal temperatures of 0, 2, or 4°C. Mortality occurred in cycles around 0°C in both populations, and little to no mortality occurred at temperatures >0°C. Individuals from both sources held in diel 0°C cycles for 72 h showed 100% mortality. Our findings support observations from published field studies that survival was limited in infested habitats subject to freezing temperatures.

  9. Freeze-cast alumina pore networks: Effects of freezing conditions and dispersion medium

    Energy Technology Data Exchange (ETDEWEB)

    Miller, S. M.; Xiao, X.; Faber, K. T.

    2015-11-01

    Alumina ceramics were freeze-cast from water- and camphene-based slurries under varying freezing conditions and examined using X-ray computed tomography (XCT). Pore network characteristics, i.e., porosity, pore size, geometric surface area, and tortuosity, were measured from XCT reconstructions and the data were used to develop a model to predict feature size from processing conditions. Classical solidification theory was used to examine relationships between pore size, temperature gradients, and freezing front velocity. Freezing front velocity was subsequently predicted from casting conditions via the two-phase Stefan problem. Resulting models for water-based samples agreed with solidification-based theories predicting lamellar spacing of binary eutectic alloys, and models for camphene-based samples concurred with those for dendritic growth. Relationships between freezing conditions and geometric surface area were also modeled by considering the inverse relationship between pore size and surface area. Tortuosity was determined to be dependent primarily on the type of dispersion medium. (C) 2015 Elsevier Ltd. All rights reserved.

  10. Food freezing with simultaneous surface dehydration: approximate prediction of weight loss during freezing and storage

    Energy Technology Data Exchange (ETDEWEB)

    Campanone, Laura A.; Salvadori, Viviana O.; Mascheroni, Rodolfo H. [Centro de Investigacion Desarollo en Criotecnologia de Alimentos (CIDCA), Facultad de Ciencias Exactas, La Plata (Argentina); MODIAL, Facultad de Ingenieria, La Plata (Argentina)

    2005-03-01

    Weight loss of unpackaged foods during freezing and later storage is an important quality and economic issue. It is originated on surface ice sublimation due to differences in water activity between food surface and the refrigerating air. Weight loss rate is determined by refrigerating conditions and product characteristics. The modelling of this phenomenon has merited very little attention; at present there are no simplified methods to predict weight losses during the freezing and the storage of unpackaged foods. In previous studies we developed a detailed model for the simultaneous heat and mass transfer during food freezing and storage with ice sublimation. Based on the information of this numerical model, simplified analytical methods for the prediction of weight loss during the freezing and the storage of unpackaged frozen foods were developed. The methods account for product characteristics and storage conditions. The prediction equations are very simple and results of their use - simulating usual freezing and storage conditions for different products - give very good accuracy when tested against the previously cited numerical model and experimental data. (Author)

  11. Freezing as a treatment to prevent the spread of Hypothenemus hampei (Coleoptera: Curculionidae), in coffee.

    Science.gov (United States)

    Hollingsworth, Robert C; Jang, Eric B; Follett, Peter A

    2013-04-01

    Coffee berry borer, Hypothenemus hampei (Ferrari) is the most serious insect pest of coffee around the world. Although it is already present in most of the world's major coffee growing regions, it is important to delay further spread and to prevent reintroductions that might include hyperparasites or improve the genetic base of existing populations. Green coffee is shipped around the world for custom blending and roasting and such shipments carry the risk of spreading H. hampei. We used heavily infested coffee berries as a surrogate for green coffee to test the freezing tolerance of H. hampei. After freezing, all life stages of H. hampei were dissected from coffee berries and mortality was assessed. Counting all life stages, > 15,000 insects were measured in this study. A temperature of approximately -15 degrees C (range, -13.9 to -15.5) for 48 h provided 100% control of all life stages. A logit regression model predicted coffee might be more economical and acceptable compared with fumigation with methyl bromide, especially for small-scale and organic growers and millers in Hawaii who ship green coffee beans to other islands for custom roasting. Freezing treatments could also be used to kill H. hampei in coffee seeds before export with minimal effects on seed germination if coffee seeds are first dried to critical water content levels in accordance with published methods.

  12. Phenotypic consequences of aneuploidy in Arabidopsis thaliana.

    Science.gov (United States)

    Henry, Isabelle M; Dilkes, Brian P; Miller, Eric S; Burkart-Waco, Diana; Comai, Luca

    2010-12-01

    Aneuploid cells are characterized by incomplete chromosome sets. The resulting imbalance in gene dosage has phenotypic consequences that are specific to each karyotype. Even in the case of Down syndrome, the most viable and studied form of human aneuploidy, the mechanisms underlying the connected phenotypes remain mostly unclear. Because of their tolerance to aneuploidy, plants provide a powerful system for a genome-wide investigation of aneuploid syndromes, an approach that is not feasible in animal systems. Indeed, in many plant species, populations of aneuploid individuals can be easily obtained from triploid individuals. We phenotyped a population of Arabidopsis thaliana aneuploid individuals containing 25 different karyotypes. Even in this highly heterogeneous population, we demonstrate that certain traits are strongly associated with the dosage of specific chromosome types and that chromosomal effects can be additive. Further, we identified subtle developmental phenotypes expressed in the diploid progeny of aneuploid parent(s) but not in euploid controls from diploid lineages. These results indicate long-term phenotypic consequences of aneuploidy that can persist after chromosomal balance has been restored. We verified the diploid nature of these individuals by whole-genome sequencing and discuss the possibility that trans-generational phenotypic effects stem from epigenetic modifications passed from aneuploid parents to their diploid progeny.

  13. Cold tolerance of the Antarctic nematodes Plectus murrayi and Scottnema lindsayae.

    Science.gov (United States)

    Wharton, David A; Raymond, Mélianie R

    2015-04-01

    The cold tolerance of the Antarctic nematodes Scottnema lindsayae and Plectus murrayi was determined using material freshly isolated from the field. Both species could survive low temperatures but the survival of S. lindsayae was greater than that of P. murrayi. Field soil temperatures in late spring-early summer indicated a minimum temperature of -19.5 °C and a maximum cooling rate of 0.71 °C min(-1). In P. murrayi grown in culture, there was no significant effect of acclimation, nor of the two culture media used, on survival after freezing but survival was greater if freezing was seeded at -1 °C than at lower temperatures. The freezing survival ability of P. murrayi is much less than that of Panagrolaimus davidi CB1, another Antarctic nematode. Cryomicroscopy indicates that P. murrayi can survive low temperatures by either cryoprotective dehydration or freezing tolerance, but that freezing tolerance is the dominant strategy. Measurable thermal hysteresis was detected only in highly concentrated extracts of the nematodes, indicating the presence of an antifreeze protein, but at the concentrations likely to be found in vivo, the major function of the ice active protein involved is probably recrystallization inhibition.

  14. Recent Developments in Smart Freezing Technology Applied to Fresh Foods.

    Science.gov (United States)

    Xu, Ji-Cheng; Zhang, Min; Mujumdar, Arun S; Adhikari, Benu

    2015-10-13

    Due to the increased awareness of consumers in sensorial and nutritional quality of frozen foods, the freezing technology has to seek new and innovative technologies for better retaining the fresh-like quality. In this article, we reviewed the recent developments in smart freezing technology applied to fresh foods. The application of these intelligent technologies and the associated underpinning concepts has greatly improved the quality of frozen foods and the freezing efficiency. These technologies are able to automatically collect the information in-line during freezing and help control the freezing process better. Smart freezing technology includes new and intelligent technologies and concepts applied to the pretreatment of the frozen product, freezing processes, cold chain logistics as well as warehouse management. These technologies enable real-time monitoring of quality during freezing process and help improve product quality and freezing efficiency. We also provided a brief overview of several sensing technologies used to achieve automatic control of individual steps of freezing process. These sensing technologies included computer vision, electronic nose, electronic tongue, digital simulation, confocal laser, near infrared spectroscopy, nuclear magnetic resonance technology and ultrasound. Understanding of the mechanism of these new technologies will be helpful for applying them to improve the quality of frozen foods.

  15. Exploiting Natural Variation in Arabidopsis

    NARCIS (Netherlands)

    Molenaar, J.A.; Keurentjes, J.J.B.

    2014-01-01

    Natural variation for many traits is present within the species Arabidopsis thaliana . This chapter describes the use of natural variation to elucidate genes underlying the regulation of quantitative traits. It deals with the development and use of mapping populations, the detection and handling of

  16. Exploiting natural variation in Arabidopsis

    NARCIS (Netherlands)

    J.A. Molenaar; J.J.B. Keurentjes

    2014-01-01

    Natural variation for many traits is present within the species Arabidopsis thaliana. This chapter describes the use of natural variation to elucidate genes underlying the regulation of quantitative traits. It deals with the development and use of mapping populations, the detection and handling of g

  17. Heterologous Expression of AtWRKY57 Confers Drought Tolerance in Oryza sativa.

    Science.gov (United States)

    Jiang, Yanjuan; Qiu, Yuping; Hu, Yanru; Yu, Diqiu

    2016-01-01

    Drought stress is a severe environmental factor that greatly restricts plant distribution and crop production. Recently, we have found that overexpressing AtWRKY57 enhanced drought tolerance in Arabidopsis thaliana. In this study, we further reported that the Arabidopsis WRKY57 transcription factor was able to confer drought tolerance to transgenic rice (Oryza sativa) plants. The enhanced drought tolerance of transgenic rice was resulted from the lower water loss rates, cell death, malondialdehyde contents and relative electrolyte leakage while a higher proline content and reactive oxygen species-scavenging enzyme activities was observed during stress conditions. Moreover, further investigation revealed that the expression levels of several stress-responsive genes were up-regulated in drought-tolerant transgenic rice plants, compared with those in wild-type plants. In addition to the drought tolerance, the AtWRKY57 over-expressing plants also had enhanced salt and PEG stress tolerances. Taken together, our study indicates that over-expressing AtWRKY57 in rice improved not only drought tolerance but also salt and PEG tolerance, demonstrating its potential role in crop improvement.

  18. Heterologous expression of AtWRKY57 confers drought tolerance in Oryza sativa

    Directory of Open Access Journals (Sweden)

    Yanjuan eJiang

    2016-02-01

    Full Text Available Drought stress is a severe environmental factor that greatly restricts plant distribution and crop production. Recently, we have found that overexpressing AtWRKY57 enhanced drought tolerance in Arabidopsis thaliana. In this study, we further reported that the Arabidopsis WRKY57 transcription factor was able to confer drought tolerance to transgenic rice (Oryza sativa plants. The enhanced drought tolerance of transgenic rice was resulted from the lower water loss rates, cell death, malondialdehyde contents and relative electrolyte leakage while a higher proline content and reactive oxygen species-scavenging enzyme activities was observed during stress conditions. Moreover, further investigation revealed that the expression levels of several stress-responsive genes were up-regulated in drought-tolerant transgenic rice plants, compared with those in wild-type plants. In addition to the drought tolerance, the AtWRKY57 over-expressing plants also had enhanced salt and PEG stress tolerances. Taken together, our study indicates that over-expressing AtWRKY57 in rice improved not only drought tolerance but also salt and PEG tolerance, demonstrating its potential role in crop improvement.

  19. An early response regulatory cluster induced by low temperature and hydrogen peroxide in seedlings of chilling-tolerant japonica rice

    Directory of Open Access Journals (Sweden)

    Jia Yulin

    2007-06-01

    Full Text Available Abstract Background Plants respond to low temperature through an intricately coordinated transcriptional network. The CBF/DREB-regulated network of genes has been shown to play a prominent role in freeze-tolerance of Arabidopsis through the process of cold acclimation (CA. Recent evidence also showed that the CBF/DREB regulon is not unique to CA but evolutionarily conserved between chilling-insensitive (temperate and chilling-sensitive (warm-season plants. In this study, the wide contrast in chilling sensitivity between indica and japonica rice was used as model to identify other regulatory clusters by integrative analysis of promoter architecture (ab initio and gene expression profiles. Results Transcriptome analysis in chilling tolerant japonica rice identified a subset of 121 'early response' genes that were upregulated during the initial 24 hours at 10°C. Among this group were four transcription factors including ROS-bZIP1 and another larger sub-group with a common feature of having as1/ocs-like elements in their promoters. Cold-induction of ROS-bZIP1 preceded the induction of as1/ocs-like element-containing genes and they were also induced by exogenous H2O2 at ambient temperature. Coordinated expression patterns and similar promoter architectures among the 'early response' genes suggest that they belong to a potential regulon (ROS-bZIP – as1/ocs regulatory module that responds to elevated levels of ROS during chilling stress. Cultivar-specific expression signatures of the candidate genes indicate a positive correlation between the activity of the putative regulon and genotypic variation in chilling tolerance. Conclusion A hypothetical model of an ROS-mediated regulon (ROS-bZIP – as1/ocs triggered by chilling stress was assembled in rice. Based on the current results, it appears that this regulon is independent of ABA and CBF/DREB, and that its activation has an important contribution in configuring the rapid responses of rice seedlings

  20. Freezing of water saturated in aluminum wool mats

    Energy Technology Data Exchange (ETDEWEB)

    Sugawara, M.; Onodera, T.; Komatsu, Y.; Tago, M. [Akita University, Department of Mechanical Engineering, Faculty of Engineering and Resource Science, Akita (Japan); Beer, H. [Technische Universitat Darmstadt, Institut fur Technische Thermodynamik, Darmstadt (Germany)

    2008-05-15

    This paper is concerned with the freezing of water saturated in aluminum wool mats (AWM) around a cooling pipe. Two arrangements of AWM around the pipe are considered, i.e. a disk-type and a roll-type. Freezing mass M(kg/m{sup 2}) in the disk type for a porosity {epsilon} = 0.95, indicates to be two times larger compared with that without AWM (i.e. {epsilon} = 1) at the freezing time t = 180 min. Even a small AWM volume fraction enhances considerably freezing of water in the disk type. However, freezing enhancement in the roll type is small compared with that of the disk type. Numerical calculation predicts well freezing at the disk type arrangement by using an anisotropy model for the effective thermal conductivity of ice/water saturated AWM, however, poor predictions for the roll type arrangement. (orig.)

  1. Freezing of water saturated in aluminum wool mats

    Science.gov (United States)

    Sugawara, M.; Onodera, T.; Komatsu, Y.; Tago, M.; Beer, H.

    2008-05-01

    This paper is concerned with the freezing of water saturated in aluminum wool mats (AWM) around a cooling pipe. Two arrangements of AWM around the pipe are considered, i.e. a disk-type and a roll-type. Freezing mass M(kg/m2) in the disk type for a porosity ɛ = 0.95, indicates to be two times larger compared with that without AWM (i.e. ɛ = 1) at the freezing time t = 180 min. Even a small AWM volume fraction enhances considerably freezing of water in the disk type. However, freezing enhancement in the roll type is small compared with that of the disk type. Numerical calculation predicts well freezing at the disk type arrangement by using an anisotropy model for the effective thermal conductivity of ice/water saturated AWM, however, poor predictions for the roll type arrangement.

  2. Freeze-drying of live virus vaccines: A review.

    Science.gov (United States)

    Hansen, L J J; Daoussi, R; Vervaet, C; Remon, J-P; De Beer, T R M

    2015-10-13

    Freeze-drying is the preferred method for stabilizing live, attenuated virus vaccines. After decades of research on several aspects of the process like the stabilization and destabilization mechanisms of the live, attenuated viruses during freeze-drying, the optimal formulation components and process settings are still matter of research. The molecular complexity of live, attenuated viruses, the multiple destabilization pathways and the lack of analytical techniques allowing the measurement of physicochemical changes in the antigen's structure during and after freeze-drying mean that they form a particular lyophilization challenge. The purpose of this review is to overview the available information on the development of the freeze-drying process of live, attenuated virus vaccines, herewith focusing on the freezing and drying stresses the viruses can undergo during processing as well as on the mechanisms and strategies (formulation and process) that are used to stabilize them during freeze-drying.

  3. Dynamical freeze-out in event-by-event hydrodynamics

    CERN Document Server

    Holopainen, Hannu

    2012-01-01

    In hydrodynamical modeling of the ultrarelativistic heavy-ion collisions the freeze-out is typically performed at a constant temperature or density. In this work we apply a dynamical freeze-out criterion, which compares the hydrodynamical expansion rate with the pion scattering rate. Recently many calculations have been done using event-by-event hydrodynamics where the initial density profile fluctuates from event to event. In these event-by-event calculations the expansion rate fluctuates strongly as well, and thus it is interesting to check how the dynamical freeze-out changes hadron distributions with respect to the constant temperature freeze-out. We present hadron spectra and elliptic flow calculated using (2+1)-dimensional ideal hydrodynamics, and show the differences between constant temperature and dynamical freeze-out criteria. We find that the differences caused by different freeze-out criteria are small in all studied cases.

  4. How to freeze drop oscillations with powders

    Science.gov (United States)

    Marston, Jeremy; Zhu, Ying; Vakarelski, Ivan; Thoroddsen, Sigurdur

    2012-11-01

    We present experiments that show when a water drop impacts onto a bed of fine, hydrophobic powder, the final form of the drop can be very different from the spherical form with which it impacts. For all drop impact speeds, the drop rebounds due to the hydrophobic nature of the powder. However, we observe that above a critical impact speed, the drop undergoes a permanent deformation to a highly non-spherical shape with a complete coverage of powder, thus creating a deformed liquid marble. This powder coating acts to freeze the drop oscillations during rebound.

  5. Freeze-fracture study of Trichomonas vaginalis

    Directory of Open Access Journals (Sweden)

    Marlene Benchimol

    1990-12-01

    Full Text Available The freeze-fracture technique was used to analyse the organization of the plasma membrane, as well as membranes of cytoplasmic organelles, of the pathogenic protozoan Trichomonas vaginalis. Rosettes formed by 4 to 14 intramembranous particles were seen on the fracture faces of the membrane lining the anterior flagella as well as in fracture faces of the plasma membrane enclosing the anterior region of the protozoan and in cytoplasmic organelles. Special organization of the membrane particles were also seen in the region of association of the recurrent flagellum to the cell body.

  6. Well-plate freeze-drying

    DEFF Research Database (Denmark)

    Trnka, Hjalte; Rantanen, Jukka; Grohganz, Holger

    2015-01-01

    , cake collapse and reconstitution time. Results: Samples freeze-dried in well-plates had an acceptable visual cake appearance. Solid form analysis by high throughput X-ray powder diffraction indicated comparable polymorphic outcome independent of the container. The expected increase in moisture level...... due to increasing amount of amorphous matter in the samples was observed in both vials and well plates. Cake collapse was found to be representative in well plates and could be effectively quantified using image analysis. Reconstitution time was also found to be equal in all three platforms. Finally...

  7. Gradient porous hydroxyapatite ceramics fabricated by freeze casting method

    Science.gov (United States)

    Zuo, Kai-hui; zhang, Yuan; Jiang, Dongliang; Zeng, Yu-Ping

    2011-04-01

    By controlling the cooling rates and the composition of slurries, the gradient porous hydroxyapatite ceramics are fabricated by the freeze casting method. According to the different cooling rate, the pores of HAP ceramics fabricated by gradient freeze casting are divided into three parts: one is lamellar pores, another is column pore and the last one is fine round pores. The laminated freeze casting is in favour of obtaining the gradient porous ceramics composed of different materials and the ceramics have unclear interfaces.

  8. Cytokinin Determines Thiol-Mediated Arsenic Tolerance and Accumulation.

    Science.gov (United States)

    Mohan, Thotegowdanapalya C; Castrillo, Gabriel; Navarro, Cristina; Zarco-Fernández, Sonia; Ramireddy, Eswarayya; Mateo, Cristian; Zamarreño, Angel M; Paz-Ares, Javier; Muñoz, Riansares; García-Mina, Jose M; Hernández, Luis E; Schmülling, Thomas; Leyva, Antonio

    2016-06-01

    The presence of arsenic in soil and water is a constant threat to plant growth in many regions of the world. Phytohormones act in the integration of growth control and stress response, but their role in plant responses to arsenic remains to be elucidated. Here, we show that arsenate [As(V)], the most prevalent arsenic chemical species in nature, causes severe depletion of endogenous cytokinins (CKs) in the model plant Arabidopsis (Arabidopsis thaliana). We found that CK signaling mutants and transgenic plants with reduced endogenous CK levels showed an As(V)-tolerant phenotype. Our data indicate that in CK-depleted plants exposed to As(V), transcript levels of As(V)/phosphate-transporters were similar or even higher than in wild-type plants. In contrast, CK depletion provoked the coordinated activation of As(V) tolerance mechanisms, leading to the accumulation of thiol compounds such as phytochelatins and glutathione, which are essential for arsenic sequestration. Transgenic CK-deficient Arabidopsis and tobacco lines show a marked increase in arsenic accumulation. Our findings indicate that CK is an important regulatory factor in plant adaptation to arsenic stress.

  9. A molecular dynamics study of freezing in a confined geometry

    Science.gov (United States)

    Ma, Wen-Jong; Banavar, Jayanth R.; Koplik, Joel

    1992-01-01

    The dynamics of freezing of a Lennard-Jones liquid in narrow channels bounded by molecular walls is studied by computer simulation. The time development of ordering is quantified and a novel freezing mechanism is observed. The liquid forms layers and subsequent in-plane ordering within a layer is accompanied by a sharpening of the layer in the transverse direction. The effects of channel size, the methods of quench, the liquid-wall interaction and the roughness of walls on the freezing mechanism are elucidated. Comparison with recent experiments on freezing in confined geometries is presented.

  10. A“TIME-SPACE” RELATED DESIGNMETHOD OF FREEZING WALL

    Institute of Scientific and Technical Information of China (English)

    陈湘生

    1996-01-01

    Artificially ground freezing (AGF) is one of the main methods to establish temporarysupport for shaft sinking in unstable water bearing strata. Domde (1915) formula based on frozensoil strength has widely been used for designing freezing wall thickness. However, it can not en-sure the stability of freezing wall, nor guarantee the safety of shaft construction as frozen depth in-creases in unstable water bearing strata. F. A. Auld (1985, 1988)[1'2] presented a designmethod of freezing wall, which is on the basis of strength and stability, together with deformationof freezing wall. This paper, according to the practice in China, describes a "time -space" relat-ed design method for deep freezing wall. The method is based on "time-space" concept, whichincludes influence of excavation rate of advance, unsupported length of freezing wall and the sumpstate on inward deformation of freezing wall, and the allowable pipe deformation caused by in-ward deformation of freezing wall. Finally, successful application of this method to the large scalecoal mine-Jining No. 2 Mine[3] in Shandong Province of China is presented. It saved much invest-ment compared with F. A. Auld's design for the same mine.

  11. Parameter Sensitivity of the Microdroplet Vacuum Freezing Process

    Directory of Open Access Journals (Sweden)

    Zhijun Zhang

    2015-01-01

    Full Text Available The vacuum freezing process of microdroplets (1 mm. Pressure and droplet diameter have an effect on cooling and freezing stages, but initial temperature only affects the cooling stage. The thermal conductivity coefficient kl affected the cooling stage, whereas ki affected the freezing stage. Heat capacity Cl affected the cooling stage, but Ci has virtually no effect on all stages. The actual latent heat of freezing ΔH was also affected. Higher density corresponds to lower cooling rate in the cooling stage.

  12. Experimental quantification of contact freezing in an electrodynamic balance

    Directory of Open Access Journals (Sweden)

    N. Hoffmann

    2013-04-01

    Full Text Available Heterogeneous nucleation of ice in a supercooled water droplet induced by an external contact with a dry aerosol particle has long been known to be more effective than freezing induced by the same nucleus immersed in the droplet. However, the experimental quantification of contact freezing is challenging. Here we report an experimental method allowing to determine the temperature dependent ice nucleation probability of size selected aerosol particles. The method uses supercooled charged water droplets suspended in a laminar flow of air containing aerosol particles as contact freezing nuclei. The rate of droplet–particle collisions is calculated numerically with account for Coulomb attraction, drag force and induced dipole interaction between charged droplet and aerosol particles. The calculation is verified by direct counting of aerosol particles collected by a levitated droplet. By repeating the experiment on individual droplets for a sufficient number of times, we are able to reproduce the statistical freezing behavior of a large ensemble of supercooled droplets and measure the average rate of freezing events. The freezing rate is equal to the product of the droplet–particle collision rate and the probability of freezing on a single contact, the latter being a function of temperature, size and composition of the contact ice nuclei. Based on these observations, we show that for the types of particles investigated so far, contact freezing is the dominating freezing mechanism on the time scale of our experiment.

  13. Experimental quantification of contact freezing in an electrodynamic balance

    Directory of Open Access Journals (Sweden)

    N. Hoffmann

    2013-09-01

    Full Text Available Heterogeneous nucleation of ice in a supercooled water droplet induced by external contact with a dry aerosol particle has long been known to be more effective than freezing induced by the same nucleus immersed in the droplet. However, the experimental quantification of contact freezing is challenging. Here we report an experimental method to determine the temperature-dependent ice nucleation probability of size-selected aerosol particles. The method is based on the suspension of supercooled charged water droplets in a laminar flow of air containing aerosol particles as contact freezing nuclei. The rate of droplet–particle collisions is calculated numerically with account for Coulomb attraction, drag force and induced dipole interaction between charged droplet and aerosol particles. The calculation is verified by direct counting of aerosol particles collected by a levitated droplet. By repeating the experiment on individual droplets for a sufficient number of times, we are able to reproduce the statistical freezing behavior of a large ensemble of supercooled droplets and measure the average rate of freezing events. The freezing rate is equal to the product of the droplet–particle collision rate and the probability of freezing on a single contact, the latter being a function of temperature, size and composition of the contact ice nuclei. Based on these observations, we show that for the types of particles investigated so far, contact freezing is the dominating freezing mechanism on the timescale of our experiment.

  14. Automated assessment of Pavlovian conditioned freezing and shock reactivity in mice using the VideoFreeze system

    Directory of Open Access Journals (Sweden)

    Stephan G Anagnostaras

    2010-09-01

    Full Text Available The Pavlovian conditioned freezing paradigm has become a prominent mouse and rat model of learning and memory, as well as of pathological fear. Due to its efficiency, reproducibility, and well-defined neurobiology, the paradigm has become widely adopted in large-scale genetic and pharmacological screens. However, one major shortcoming of the use of freezing behavior has been that it has required the use of tedious hand scoring, or a variety of proprietary automated methods that are often poorly validated or difficult to obtain and implement. Here we report an extensive validation of the Video Freeze system in mice, a turn-key all-inclusive system for fear conditioning in small animals. Using digital video and near-infrared lighting, the system achieved outstanding performance in scoring both freezing and movement. Given the large-scale adoption of the conditioned freezing paradigm, we encourage similar validation of other automated systems for scoring freezing, or other behaviors.

  15. Reference: 710 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available n factor family in Arabidopsis (Arabidopsis thaliana). Treatment with abscisic acid (ABA) induced AtMYB44 tr...anscript accumulation within 30 min. The gene was also activated under various abiotic stre...sses, such as dehydration, low temperature, and salinity. In transgenic Arabidopsis carrying an At...MYB44 promoter-driven beta-glucuronidase (GUS) construct, strong GUS activity was observed in the vasculature... and leaf epidermal guard cells. Transgenic Arabidopsis overexpressing AtMYB44 is more

  16. The interaction of Arabidopsis with Piriformospora indica shifts from initial transient stress induced by fungus-released chemical mediators to a mutualistic interaction after physical contact of the two symbionts

    OpenAIRE

    Vahabi, K.; Sherameti, I.; Bakshi, M.; Mrozinska, A.; Ludwig, A.; M. Reichelt; Oelmüller, R

    2015-01-01

    Background Piriformospora indica, an endophytic fungus of Sebacinales, colonizes the roots of many plant species including Arabidopsis thaliana. The symbiotic interaction promotes plant performance, growth and resistance/tolerance against abiotic and biotic stress. Results We demonstrate that exudated compounds from the fungus activate stress and defense responses in the Arabidopsis roots and shoots before the two partners are in physical contact. They induce stomata closure, stimulate reacti...

  17. Asset Freezing: Smart Sanction or Criminal Charge?

    Directory of Open Access Journals (Sweden)

    Wouter de Zanger

    2011-02-01

    Full Text Available In this article the question is asked whether asset freezing can be qualified as a criminal charge within the meaning of Article6 ECHR and if yes, what effects this qualification may have on the legislative framework on so called smart sanctions. Byanalysing Community and EU law and case law of the European Court of Human Rights, General Court of Instance andCourt of Justice of the European Communities the authors give an overview of the notion and possible qualification of assetfreezing as a criminal charge. The article further focusses on the consequenses of qualifying asset freezing as a criminal chargeunder ECHR and EC/EU law and concludes by answering the aforementioned question.This article is a rewrite of a research paper written under supervision of prof. dr. J.A.E. Vervaele and prof. dr. C.H. Brants(Willem Pompe Institute for Criminal Law and Criminology, Utrecht University School of Law, whom the authors wouldlike to thank for their useful comments and supervision.

  18. Spray freeze drying of YSZ nanopowder

    Science.gov (United States)

    Raghupathy, Bala P. C.; Binner, J. G. P.

    2012-07-01

    Spray freeze drying of yttria stabilised zirconia nanopowders with a primary particle size of 16 nm has been undertaken using different solids content starting suspensions, with the effect of the latter on the flowability and crushability of the granules being investigated. The flowability and fill density of the granules increased with an increase in the solid content of the starting suspension, whilst the crushability decreased. The powder flowability, measured using a Hall flowmeter and model shoe-die filling tests, showed that the flowability of otherwise poorly flowable nanopowders can be improved to match that of the commercial spray dried submicron powder. The 5.5 vol.% solid content based suspension yielded soft agglomerates whilst a 28 vol.% solid content suspension formed hard agglomerates on spray freeze drying; the granule relics were visible in the fracture surface of the die pressed green compact in the latter case. The increase in granule strength is explained by the reduction in inter-particle distance based on the theories developed by Rumpf and Kendall. The flaw sizes computed using the Kendall model are comparable with those seen in the micrographs of the granule. With an optimum solid content, it is possible to have a granulated nanopowder with reasonable flowability and compactability resulting in homogeneous green bodies with 54 % of theoretical density.

  19. Effect of freezing on rabbit cultured chondrocytes

    Directory of Open Access Journals (Sweden)

    R.R Filgueiras

    2011-02-01

    Full Text Available This work evaluated the effect of freezing on chondrocytes maintained in culture, aiming the establishment of a cell bank for future application as heterologous implant. Chondrocytes extracted from joint cartilage of nine healthy New Zealand White rabbits were cultivated and frozen with the cryoprotector 5% dimethylsulfoxide for six months. Phenotypic and scanning electron microscopy analyses were carried out to identify morphological and functional differences between fresh and thawed cells. After enzymatic digestion, a total of 4.8x10(5cells per rabbit were obtained. Fresh chondrocytes showed a high mitotic rate and abundant matrix was present up to 60 days of culture. Loss of phenotypic stability was notable in the thawed chondrocytes, with a low labeling of proteoglycans and weak immunostaining of type II collagen. The present study showed important loss of chondrocyte viability under the freezing conditions. For future in vivo studies of heterologous implant, these results suggests that a high number of cells should be implanted in the host site in order to achieve an adequate number of viable cells. Furthermore, the chondrocytes should be implanted after two weeks of culture, when the highest viability rate is found

  20. Estimating the impact of single and multiple freezes on video quality

    NARCIS (Netherlands)

    Van Kester, S.; Xiao, T.; Kooij, R.E.; Brunnstrom, K.; Ahmed, O.K.

    2011-01-01

    This paper studies the impact of freezing of video on quality as experienced by users. Two types of freezes are investigated. First a freeze where the image pauses, so no frames were lost (frame halt). In the second type of freeze, the image freezes and skips that part of the video (frame drop). Mea

  1. Lactose tolerance tests

    Science.gov (United States)

    Hydrogen breath test for lactose tolerance ... Two common methods include: Lactose tolerance blood test Hydrogen breath test The hydrogen breath test is the preferred method. It measures the amount of hydrogen ...

  2. Characterization of Arabidopsis calreticulin mutants in response to calcium and salinity stresses

    Institute of Scientific and Technical Information of China (English)

    Zhigang Li; Yangrong Cao; Jinsong Zhang; Shouyi Chen

    2008-01-01

    As an important calcium-binding protein,calreticulin plays an important role in regulating calcium homeostasis in endoplasmic reticulum (ER) of plants.Here,we identified three loss-of-function mutants ofcalreticulin genes in Arabidopsis to demonstrate the function of calreticulin in response to calcium and salinity stresses.There are three genes encoding calreticulin in Arabidopsis,and they are named AtCRT1,2,and 3,respectively.We found that both single mutant of crt3 and double mutant of crtl crt2 were more sensitive to low calcium environment than wild-type Arabidopsis.Moreover,crt3 mutant showed more sensitivity to salt treatment at germination stage,but tolerance to salt stress at later stage compared with wild-type plant.However,there was no obvious growth difference in the mutant crt1 and crt2 compared with wild-type Arabidopsis under calcium and salt stresses.These results suggest that calreticulin functions in plant responses to calcium and salt stresses.

  3. Plasticity of the Arabidopsis root system under nutrient deficiencies.

    Science.gov (United States)

    Gruber, Benjamin D; Giehl, Ricardo F H; Friedel, Swetlana; von Wirén, Nicolaus

    2013-09-01

    Plant roots show a particularly high variation in their morphological response to different nutrient deficiencies. Although such changes often determine the nutrient efficiency or stress tolerance of plants, it is surprising that a comprehensive and comparative analysis of root morphological responses to different nutrient deficiencies has not yet been conducted. Since one reason for this is an inherent difficulty in obtaining nutrient-deficient conditions in agar culture, we first identified conditions appropriate for producing nutrient-deficient plants on agar plates. Based on a careful selection of agar specifically for each nutrient being considered, we grew Arabidopsis (Arabidopsis thaliana) plants at four levels of deficiency for 12 nutrients and quantified seven root traits. In combination with measurements of biomass and elemental concentrations, we observed that the nutritional status and type of nutrient determined the extent and type of changes in root system architecture (RSA). The independent regulation of individual root traits further pointed to a differential sensitivity of root tissues to nutrient limitations. To capture the variation in RSA under different nutrient supplies, we used principal component analysis and developed a root plasticity chart representing the overall modulations in RSA under a given treatment. This systematic comparison of RSA responses to nutrient deficiencies provides a comprehensive view of the overall changes in root plasticity induced by the deficiency of single nutrients and provides a solid basis for the identification of nutrient-sensitive steps in the root developmental program.

  4. References on Compression of Freeze-Dried Foods

    Science.gov (United States)

    1978-08-01

    fully freeze-dried materials are moistened by resorption prior to compression. Compression in vacuum was successfully demonstrated. Similarly, freeze...room temperature). Bars were evaluated for cohesiveness, dimensional stability under pressure, ease of shear by the incisors and subsequent...under pressure, ease of shear by the incisors and subsequent mastication. Observations on free fatty acids, peroxide value and browning (fluorescence

  5. Determination of Freeze-out Conditions from Lattice QCD Calculations

    CERN Document Server

    Karsch, Frithjof

    2012-01-01

    Freeze-out conditions in Heavy Ion Collisions are generally determined by comparing experimental results for ratios of particle yields with theoretical predictions based on applications of the Hadron Resonance Gas model. We discuss here how this model dependent determination of freeze-out parameters may eventually be replaced by theoretical predictions based on equilibrium QCD thermodynamics.

  6. Molecular evolutionary analysis of the Alfin-like protein family in Arabidopsis lyrata, Arabidopsis thaliana, and Thellungiella halophila.

    Directory of Open Access Journals (Sweden)

    Yu Song

    Full Text Available In previous studies, the Alfin1 gene, a transcription factor, enhanced salt tolerance in alfalfa, primarily through altering gene expression levels in the root. Here, we examined the molecular evolution of the Alfin-like (AL proteins in two Arabidopsis species (A. lyrata and A. thaliana and a salt-tolerant close relative Thellungiella halophila. These AL-like proteins could be divided into four groups and the two known DUF3594 and PHD-finger domains had co-evolved within each group of genes, irrespective of species, due to gene duplication events in the common ancestor of all three species while gene loss was observed only in T. halophila. To detect whether natural selection acted in the evolution of AL genes, we calculated synonymous substitution ratios (dn/ds and codon usage statistics, finding positive selection operated on four branches and significant differences in biased codon usage in the AL family between T. halophila and A. lyrata or A. thaliana. Distinctively, only the AL7 branch was under positive selection on the PHD-finger domain and the three members on the branch showed the smallest difference when codon bias was evaluated among the seven clusters. Functional analysis based on transgenic overexpression lines and T-DNA insertion mutants indicated that salt-stress-induced AtAL7 could play a negative role in salt tolerance of A. thaliana, suggesting that adaptive evolution occurred in the members of AL gene family.

  7. Molecular evolutionary analysis of the Alfin-like protein family in Arabidopsis lyrata, Arabidopsis thaliana, and Thellungiella halophila.

    Science.gov (United States)

    Song, Yu; Gao, Jie; Yang, Fengxi; Kua, Chai-Shian; Liu, Jingxin; Cannon, Charles H

    2013-01-01

    In previous studies, the Alfin1 gene, a transcription factor, enhanced salt tolerance in alfalfa, primarily through altering gene expression levels in the root. Here, we examined the molecular evolution of the Alfin-like (AL) proteins in two Arabidopsis species (A. lyrata and A. thaliana) and a salt-tolerant close relative Thellungiella halophila. These AL-like proteins could be divided into four groups and the two known DUF3594 and PHD-finger domains had co-evolved within each group of genes, irrespective of species, due to gene duplication events in the common ancestor of all three species while gene loss was observed only in T. halophila. To detect whether natural selection acted in the evolution of AL genes, we calculated synonymous substitution ratios (dn/ds) and codon usage statistics, finding positive selection operated on four branches and significant differences in biased codon usage in the AL family between T. halophila and A. lyrata or A. thaliana. Distinctively, only the AL7 branch was under positive selection on the PHD-finger domain and the three members on the branch showed the smallest difference when codon bias was evaluated among the seven clusters. Functional analysis based on transgenic overexpression lines and T-DNA insertion mutants indicated that salt-stress-induced AtAL7 could play a negative role in salt tolerance of A. thaliana, suggesting that adaptive evolution occurred in the members of AL gene family.

  8. The Effect of Freezing Stress on Percentage of Electrolytes Leakage and Survival of Flixweed (Descurainia sophia L. Seedlings

    Directory of Open Access Journals (Sweden)

    E Izadi-Darbandi

    2016-10-01

    Full Text Available Introduction Flixweed (Descurainia sophia L. is a medicinal plant from Brassicaceae family which also known as a weed for winter cereals and oil seed rape. Low temperatures are one of the most important abiotic stresses that threat Flixweed growth and productivity. Therefore it is important to recognize the freeze tolerance of Flixweed for successful planting and utilization in cold regions such as Mashhad in Khorasan Razavi Province (Iran’s north. east. Among many laboratory methods which have been developed to estimate and to evaluate plants response or their tolerance to freez¬ing temperatures, electrolyte leakage (EL test is widely used. This test is based on this principle that damage to the cell membranes results in enhanced leakage of solutes into the apoplastic water, hence recording the amount of leakage after stress treatments provides an estimation of tissue injury. Indeed continuing integration of plasma membrane is one important factor for survival of plants under freezing stress and any disturbance in membrane structure can lead to damage and death. So determination of LT50 point or critical temperature for electrolytes leakage and survival of plant is the most reliable, quantitative and simple methods for evaluating the cold tolerance of plants. The aim of this trial was to determine the LT50 according to the EL and SU% for Flixweed ecotypes. Materials and Methods In order to evaluate freeze tolerance in Flixweed, a factorial experiment based on completely randomized design with three replications was carried out in college of agriculture, Ferdowsi University of Mashhad. Experimental factors included five ecotypes of Flixweed (Eghlid, Sabzewar, Hamedan, Torbat-e-Jam and Neyshabour and 10 freezing temperature levels (0, -2,-4, -6, -8,-10,-12,-14,-16 and -18°C. Flixweed seeds were cultivated in pots in autumn of 2008 and were grown until 5-7 leaf stage under natural weather conditions for acclimation. Then to apply freezing

  9. An International Bioinformatics Infrastructure to Underpin the Arabidopsis Community

    Science.gov (United States)

    The future bioinformatics needs of the Arabidopsis community as well as those of other scientific communities that depend on Arabidopsis resources were discussed at a pair of recent meetings held by the Multinational Arabidopsis Steering Committee (MASC) and the North American Arabidopsis Steering C...

  10. Arabidopsis CDS blastp result: AK240652 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK240652 J023098G11 At5g63090.2 68418.m07919 LOB domain protein / lateral organ boundaries... protein (LOB) identical to LOBa [Arabidopsis thaliana] GI:17484100, SP|Q9FML4 LATERAL ORGAN BOUNDARIES protein {Arabidopsis thaliana} 1e-13 ...

  11. Arabidopsis CDS blastp result: AK241761 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK241761 J065205C18 At5g63090.1 68418.m07918 LOB domain protein / lateral organ boundaries... protein (LOB) identical to LOBa [Arabidopsis thaliana] GI:17484100, SP|Q9FML4 LATERAL ORGAN BOUNDARIES protein {Arabidopsis thaliana} 5e-32 ...

  12. Arabidopsis CDS blastp result: AK240652 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK240652 J023098G11 At5g63090.1 68418.m07918 LOB domain protein / lateral organ boundaries... protein (LOB) identical to LOBa [Arabidopsis thaliana] GI:17484100, SP|Q9FML4 LATERAL ORGAN BOUNDARIES protein {Arabidopsis thaliana} 1e-13 ...

  13. Arabidopsis CDS blastp result: AK240652 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK240652 J023098G11 At5g63090.4 68418.m07921 LOB domain protein / lateral organ boundaries... protein (LOB) identical to LOBa [Arabidopsis thaliana] GI:17484100, SP|Q9FML4 LATERAL ORGAN BOUNDARIES protein {Arabidopsis thaliana} 1e-13 ...

  14. Arabidopsis CDS blastp result: AK241761 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK241761 J065205C18 At5g63090.3 68418.m07920 LOB domain protein / lateral organ boundaries... protein (LOB) identical to LOBa [Arabidopsis thaliana] GI:17484100, SP|Q9FML4 LATERAL ORGAN BOUNDARIES protein {Arabidopsis thaliana} 5e-32 ...

  15. Arabidopsis CDS blastp result: AK241761 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK241761 J065205C18 At5g63090.2 68418.m07919 LOB domain protein / lateral organ boundaries... protein (LOB) identical to LOBa [Arabidopsis thaliana] GI:17484100, SP|Q9FML4 LATERAL ORGAN BOUNDARIES protein {Arabidopsis thaliana} 5e-32 ...

  16. Arabidopsis CDS blastp result: AK241761 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK241761 J065205C18 At5g63090.4 68418.m07921 LOB domain protein / lateral organ boundaries... protein (LOB) identical to LOBa [Arabidopsis thaliana] GI:17484100, SP|Q9FML4 LATERAL ORGAN BOUNDARIES protein {Arabidopsis thaliana} 5e-32 ...

  17. Arabidopsis CDS blastp result: AK240652 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK240652 J023098G11 At5g63090.3 68418.m07920 LOB domain protein / lateral organ boundaries... protein (LOB) identical to LOBa [Arabidopsis thaliana] GI:17484100, SP|Q9FML4 LATERAL ORGAN BOUNDARIES protein {Arabidopsis thaliana} 1e-13 ...

  18. Arabidopsis CDS blastp result: AK105527 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK105527 001-127-G05 At5g63090.4 LOB domain protein / lateral organ boundaries prot...ein (LOB) identical to LOBa [Arabidopsis thaliana] GI:17484100, SP|Q9FML4 LATERAL ORGAN BOUNDARIES protein {Arabidopsis thaliana} 3e-52 ...

  19. Using "Arabidopsis" Genetic Sequences to Teach Bioinformatics

    Science.gov (United States)

    Zhang, Xiaorong

    2009-01-01

    This article describes a new approach to teaching bioinformatics using "Arabidopsis" genetic sequences. Several open-ended and inquiry-based laboratory exercises have been designed to help students grasp key concepts and gain practical skills in bioinformatics, using "Arabidopsis" leucine-rich repeat receptor-like kinase (LRR…

  20. Arabidopsis CDS blastp result: AK240730 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK240730 J043030K09 At2g32440.1 68415.m03963 ent-kaurenoic acid hydroxylase, putati...ve / cytochrome P450, putative identical to ent-kaurenoic acid hydroxylase / cytochrome P450 CYP88A (GI:1302...1856) [Arabidopsis thaliana]; similar to ent-kaurenoic acid hydroxylase [Arabidopsis thaliana] GI:13021853 2e-11 ...