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Sample records for arabidopsis root growth

  1. Mutations in leaf starch metabolism modulate the diurnal root growth profiles of Arabidopsis thaliana

    OpenAIRE

    Yazdanbakhsh, Nima; FISAHN, JOACHIM

    2011-01-01

    Roots of Arabidopsis thaliana exhibit stable diurnal growth profiles that are controlled by the circadian clock. Here we describe the effects of mutations in leaf starch metabolism on the diurnal root growth characteristics of Arabidopsis thaliana. High temporal and spatial resolution video imaging was performed to quantify the growth kinetics of Arabidopsis wild-type as well as pgm, sex1, mex1, dpe1 and dpe2 starch metabolism mutants grown in three different photoperiods. As a result, root g...

  2. Plant-in-chip: Microfluidic system for studying root growth and pathogenic interactions in Arabidopsis

    Science.gov (United States)

    Parashar, Archana; Pandey, Santosh

    2011-06-01

    We report a microfluidic platform for the hydroponic growth of Arabidopsis plants with high-resolution visualization of root development and root-pathogen interactions. The platform comprises a set of parallel microchannels with individual input/output ports where 1-day old germinated seedlings are initially placed. Under optimum conditions, a root system grows in each microchannel and its images are recorded over a 198-h period. Different concentrations of plant growth media show different root growth characteristics. Later, the developed roots are inoculated with two plant pathogens (nematodes and zoospores) and their physicochemical interactions with the live root systems are observed.

  3. Hydrogen peroxide modulates abscisic acid signaling in root growth and development in Arabidopsis

    Institute of Scientific and Technical Information of China (English)

    BAI Ling; ZHOU Yun; ZHANG XiaoRan; SONG ChunPeng; Gao MingQing

    2007-01-01

    Exogenous abscisic acid (ABA) can inhibit root growth and promote formation of more root hairs in the root tip of Arabidopsis. However, the molecular mechanisms that underlie root ABA signaling are largely unknown. We report here that hydrogen peroxide (H2O2) reduces the root growth of wild type,and the phenotype of H2O2 on the root growth is similar to ABA response. Meanwhile ABA-induced changes in the morphology of root system can be partly reversed by ascorbic acid in wild type and abolished in NADPH oxidase defective mutant atrbohF and atrbohC. Further, ABA can induce H2O2 accumulation in the root cells and enhance transcription level of OXI1, which is necessary for many more AOS-dependent processes such as root hair growth in Arabidopsis. Our results suggest that H2O2 as an important signal molecule is required for the ABA-regulated root growth and development in Arabidopsis.

  4. Glucose and auxin signaling interaction in controlling Arabidopsis thaliana seedlings root growth and development.

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    Bhuwaneshwar S Mishra

    Full Text Available BACKGROUND: Plant root growth and development is highly plastic and can adapt to many environmental conditions. Sugar signaling has been shown to affect root growth and development by interacting with phytohormones such as gibberellins, cytokinin and abscisic acid. Auxin signaling and transport has been earlier shown to be controlling plant root length, number of lateral roots, root hair and root growth direction. PRINCIPAL FINDINGS: Increasing concentration of glucose not only controls root length, root hair and number of lateral roots but can also modulate root growth direction. Since root growth and development is also controlled by auxin, whole genome transcript profiling was done to find out the extent of interaction between glucose and auxin response pathways. Glucose alone could transcriptionally regulate 376 (62% genes out of 604 genes affected by IAA. Presence of glucose could also modulate the extent of regulation 2 fold or more of almost 63% genes induced or repressed by IAA. Interestingly, glucose could affect induction or repression of IAA affected genes (35% even if glucose alone had no significant effect on the transcription of these genes itself. Glucose could affect auxin biosynthetic YUCCA genes family members, auxin transporter PIN proteins, receptor TIR1 and members of a number of gene families including AUX/IAA, GH3 and SAUR involved in auxin signaling. Arabidopsis auxin receptor tir1 and response mutants, axr2, axr3 and slr1 not only display a defect in glucose induced change in root length, root hair elongation and lateral root production but also accentuate glucose induced increase in root growth randomization from vertical suggesting glucose effects on plant root growth and development are mediated by auxin signaling components. CONCLUSION: Our findings implicate an important role of the glucose interacting with auxin signaling and transport machinery to control seedling root growth and development in changing nutrient

  5. The cytokinin response factors modulate root and shoot growth and promote leaf senescence in Arabidopsis.

    Science.gov (United States)

    Raines, Tracy; Shanks, Carly; Cheng, Chia-Yi; McPherson, Duncan; Argueso, Cristiana T; Kim, Hyo J; Franco-Zorrilla, José M; López-Vidriero, Irene; Solano, Roberto; Vaňková, Radomíra; Schaller, G Eric; Kieber, Joseph J

    2016-01-01

    The cytokinin response factors (CRFs) are a group of related AP2/ERF transcription factors that are transcriptionally induced by cytokinin. Here we explore the role of the CRFs in Arabidopsis thaliana growth and development by analyzing lines with decreased and increased CRF function. While single crf mutations have no appreciable phenotypes, disruption of multiple CRFs results in larger rosettes, delayed leaf senescence, a smaller root apical meristem (RAM), reduced primary and lateral root growth, and, in etiolated seedlings, shorter hypocotyls. In contrast, overexpression of CRFs generally results in the opposite phenotypes. The crf1,2,5,6 quadruple mutant is embryo lethal, indicating that CRF function is essential for embryo development. Disruption of the CRFs results in partially insensitivity to cytokinin in a root elongation assay and affects the basal expression of a significant number of cytokinin-regulated genes, including the type-A ARRs, although it does not impair the cytokinin induction of the type-A ARRs. Genes encoding homeobox transcription factors are mis-expressed in the crf1,3,5,6 mutant, including STIMPY/WOX9 that is required for root and shoot apical meristem maintenance roots and which has previously been linked to cytokinin. These results indicate that the CRF transcription factors play important roles in multiple aspects of plant growth and development, in part through a complex interaction with cytokinin signaling. PMID:26662515

  6. Glucose and Auxin Signaling Interaction in Controlling Arabidopsis thaliana Seedlings Root Growth and Development

    OpenAIRE

    Mishra, Bhuwaneshwar S.; Manjul Singh; Priyanka Aggrawal; Ashverya Laxmi

    2009-01-01

    BACKGROUND: Plant root growth and development is highly plastic and can adapt to many environmental conditions. Sugar signaling has been shown to affect root growth and development by interacting with phytohormones such as gibberellins, cytokinin and abscisic acid. Auxin signaling and transport has been earlier shown to be controlling plant root length, number of lateral roots, root hair and root growth direction. PRINCIPAL FINDINGS: Increasing concentration of glucose not only controls root ...

  7. Trichoderma spp. Improve growth of Arabidopsis seedlings under salt stress through enhanced root development, osmolite production, and Na⁺ elimination through root exudates.

    Science.gov (United States)

    Contreras-Cornejo, Hexon Angel; Macías-Rodríguez, Lourdes; Alfaro-Cuevas, Ruth; López-Bucio, José

    2014-06-01

    Salt stress is an important constraint to world agriculture. Here, we report on the potential of Trichoderma virens and T. atroviride to induce tolerance to salt in Arabidopsis seedlings. We first characterized the effect of several salt concentrations on shoot biomass production and root architecture of Arabidopsis seedlings. We found that salt repressed plant growth and root development in a dose-dependent manner by blocking auxin signaling. Analysis of the wild type and eir1, aux1-7, arf7arf19, and tir1abf2abf19 auxin-related mutants revealed a key role for indole-3-acetic acid (IAA) signaling in mediating salt tolerance. We also found that T. virens (Tv29.8) and T. atroviride (IMI 206040) promoted plant growth in both normal and saline conditions, which was related to the induction of lateral roots and root hairs through auxin signaling. Arabidopsis seedlings grown under saline conditions inoculated with Trichoderma spp. showed increased levels of abscissic acid, L-proline, and ascorbic acid, and enhanced elimination of Na⁺ through root exudates. Our data show the critical role of auxin signaling and root architecture to salt tolerance in Arabidopsis and suggest that these fungi may enhance the plant IAA level as well as the antioxidant and osmoprotective status of plants under salt stress. PMID:24502519

  8. Cell wall-associated ROOT HAIR SPECIFIC 10, a proline-rich receptor-like kinase, is a negative modulator of Arabidopsis root hair growth.

    Science.gov (United States)

    Hwang, Youra; Lee, Hyodong; Lee, Young-Sook; Cho, Hyung-Taeg

    2016-04-01

    Plant cell growth is restricted by the cell wall, and cell wall dynamics act as signals for the cytoplasmic and nuclear events of cell growth. Among various receptor kinases, ROOT HAIR SPECIFIC 10 (RHS10) belongs to a poorly known receptor kinase subfamily with a proline-rich extracellular domain. Here, we report that RHS10 defines the root hair length of Arabidopsis thaliana by negatively regulating hair growth. RHS10 modulates the duration of root hair growth rather than the growth rate. As poplar and rice RHS10 orthologs also showed a root hair-inhibitory function, this receptor kinase-mediated function appears to be conserved in angiosperms. RHS10 showed a strong association with the cell wall, most probably through its extracellular proline-rich domain (ECD). Deletion analysis of the ECD demonstrated that a minimal extracellular part, which includes a few proline residues, is required for RHS10-mediated root hair inhibition. RHS10 suppressed the accumulation of reactive oxygen species (ROS) in the root, which are necessary for root hair growth. A yeast two-hybrid screening identified an RNase (RNS2) as a putative downstream target of RHS10. Accordingly, RHS10 overexpression decreased and RHS10 loss increased RNA levels in the hair-growing root region. Our results suggest that RHS10 mediates cell wall-associated signals to maintain proper root hair length, at least in part by regulating RNA catabolism and ROS accumulation. PMID:26884603

  9. Arabidopsis thaliana root elongation growth is sensitive to lunisolar tidal acceleration and may also be weakly correlated with geomagnetic variations

    Science.gov (United States)

    Barlow, Peter W.; Fisahn, Joachim; Yazdanbakhsh, Nima; Moraes, Thiago A.; Khabarova, Olga V.; Gallep, Cristiano M.

    2013-01-01

    Background Correlative evidence suggests a relationship between the lunisolar tidal acceleration and the elongation rate of arabidopsis roots grown under free-running conditions of constant low light. Methods Seedlings of Arabidopsis thaliana were grown in a controlled-climate chamber maintained at a constant temperature and subjected to continuous low-level illumination from fluorescent tubes, conditions that approximate to a ‘free-running’ state in which most of the abiotic factors that entrain root growth rates are excluded. Elongation of evenly spaced, vertical primary roots was recorded continuously over periods of up to 14 d using high temporal- and spatial-resolution video imaging and were analysed in conjunction with geophysical variables. Key Results and Conclusions The results confirm the lunisolar tidal/root elongation relationship. Also presented are relationships between the hourly elongation rates and the contemporaneous variations in geomagnetic activity, as evaluated from the disturbance storm time and ap indices. On the basis of time series of root elongation rates that extend over ≥4 d and recorded at different seasons of the year, a provisional conclusion is that root elongation responds to variation in the lunisolar force and also appears to adjust in accordance with variations in the geomagnetic field. Thus, both lunisolar tidal acceleration and the geomagnetic field should be considered as modulators of root growth rate, alongside other, stronger and more well-known abiotic environmental regulators, and perhaps unexplored factors such as air ions. Major changes in atmospheric pressure are not considered to be a factor contributing to oscillations of root elongation rate. PMID:23532042

  10. Root gravitropism in maize and Arabidopsis

    Science.gov (United States)

    Evans, Michael L.

    1993-01-01

    Research during the period 1 March 1992 to 30 November 1993 focused on improvements in a video digitizer system designed to automate the recording of surface extension in plants responding to gravistimulation. The improvements included modification of software to allow detailed analysis of localized extension patterns in roots of Arabidopsis. We used the system to analyze the role of the postmitotic isodiametric growth zone (a region between the meristem and the elongation zone) in the response of maize roots to auxin, calcium, touch and gravity. We also used the system to analyze short-term auxin and gravitropic responses in mutants of Arabidopsis with reduced auxin sensitivity. In a related project, we studied the relationship between growth rate and surface electrical currents in roots by examining the effects of gravity and thigmostimulation on surface potentials in maize roots.

  11. Growth performance and root transcriptome remodeling of Arabidopsis in response to Mars-like levels of magnesium sulfate.

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    Anne M Visscher

    Full Text Available BACKGROUND: Martian regolith (unconsolidated surface material is a potential medium for plant growth in bioregenerative life support systems during manned missions on Mars. However, hydrated magnesium sulfate mineral levels in the regolith of Mars can reach as high as 10 wt%, and would be expected to be highly inhibitory to plant growth. METHODOLOGY AND PRINCIPAL FINDINGS: Disabling ion transporters AtMRS2-10 and AtSULTR1;2, which are plasma membrane localized in peripheral root cells, is not an effective way to confer tolerance to magnesium sulfate soils. Arabidopsis mrs2-10 and sel1-10 knockout lines do not mitigate the growth inhibiting impacts of high MgSO(4.7H(2O concentrations observed with wildtype plants. A global approach was used to identify novel genes with potential to enhance tolerance to high MgSO(4.7H(2O (magnesium sulfate stress. The early Arabidopsis root transcriptome response to elevated concentrations of magnesium sulfate was characterized in Col-0, and also between Col-0 and the mutant line cax1-1, which was confirmed to be relatively tolerant of high levels of MgSO(4.7H(2O in soil solution. Differentially expressed genes in Col-0 treated for 45 min. encode enzymes primarily involved in hormone metabolism, transcription factors, calcium-binding proteins, kinases, cell wall related proteins and membrane-based transporters. Over 200 genes encoding transporters were differentially expressed in Col-0 up to 180 min. of exposure, and one of the first down-regulated genes was CAX1. The importance of this early response in wildtype Arabidopsis is exemplified in the fact that only four transcripts were differentially expressed between Col-0 and cax1-1 at 180 min. after initiation of treatment. CONCLUSIONS/SIGNIFICANCE: The results provide a solid basis for the understanding of the metabolic response of plants to elevated magnesium sulfate soils; it is the first transcriptome analysis of plants in this environment. The results foster

  12. Arabidopsis Myrosinase Genes AtTGG4 and AtTGG5 Are Root-Tip Specific and Contribute to Auxin Biosynthesis and Root-Growth Regulation

    Directory of Open Access Journals (Sweden)

    Lili Fu

    2016-06-01

    Full Text Available Plant myrosinases (β-thioglucoside glucohydrolases are classified into two subclasses, Myr I and Myr II. The biological function of Myr I has been characterized as a major biochemical defense against insect pests and pathogens in cruciferous plants. However, the biological function of Myr II remains obscure. We studied the function of two Myr II member genes AtTGG4 and AtTGG5 in Arabidopsis. RT-PCR showed that both genes were specifically expressed in roots. GUS-assay revealed that both genes were expressed in the root-tip but with difference: AtTGG4 was expressed in the elongation zone of the root-tip, while AtTGG5 was expressed in the whole root-tip. Moreover, myrosin cells that produce and store the Myr I myrosinases in aboveground organs were not observed in roots, and AtTGG4 and AtTGG5 were expressed in all cells of the specific region. A homozygous double mutant line tgg4tgg5 was obtained through cross-pollination between two T-DNA insertion lines, tgg4E8 and tgg5E12, by PCR-screening in the F2 and F3 generations. Analysis of myrosinase activity in roots of mutants revealed that AtTGG4 and AtTGG5 had additive effects and contributed 35% and 65% myrosinase activity in roots of the wild type Col-0, respectively, and myrosinase activity in tgg4tgg5 was severely repressed. When grown in Murashiege & Skoog (MS medium or in soil with sufficient water, Col-0 had the shortest roots, and tgg4tgg5 had the longest roots, while tgg4E8 and tgg5E12 had intermediate root lengths. In contrast, when grown in soil with excessive water, Col-0 had the longest roots, and tgg4tgg5 had the shortest roots. These results suggested that AtTGG4 and AtTGG5 regulated root growth and had a role in flood tolerance. The auxin-indicator gene DR5::GUS was then introduced into tgg4tgg5 by cross-pollination. DR5::GUS expression patterns in seedlings of F1, F2, and F3 generations indicated that AtTGG4 and AtTGG5 contributed to auxin biosynthesis in roots. The proposed

  13. Arabidopsis Myrosinase Genes AtTGG4 and AtTGG5 Are Root-Tip Specific and Contribute to Auxin Biosynthesis and Root-Growth Regulation.

    Science.gov (United States)

    Fu, Lili; Wang, Meng; Han, Bingying; Tan, Deguan; Sun, Xuepiao; Zhang, Jiaming

    2016-01-01

    Plant myrosinases (β-thioglucoside glucohydrolases) are classified into two subclasses, Myr I and Myr II. The biological function of Myr I has been characterized as a major biochemical defense against insect pests and pathogens in cruciferous plants. However, the biological function of Myr II remains obscure. We studied the function of two Myr II member genes AtTGG4 and AtTGG5 in Arabidopsis. RT-PCR showed that both genes were specifically expressed in roots. GUS-assay revealed that both genes were expressed in the root-tip but with difference: AtTGG4 was expressed in the elongation zone of the root-tip, while AtTGG5 was expressed in the whole root-tip. Moreover, myrosin cells that produce and store the Myr I myrosinases in aboveground organs were not observed in roots, and AtTGG4 and AtTGG5 were expressed in all cells of the specific region. A homozygous double mutant line tgg4tgg5 was obtained through cross-pollination between two T-DNA insertion lines, tgg4E8 and tgg5E12, by PCR-screening in the F2 and F3 generations. Analysis of myrosinase activity in roots of mutants revealed that AtTGG4 and AtTGG5 had additive effects and contributed 35% and 65% myrosinase activity in roots of the wild type Col-0, respectively, and myrosinase activity in tgg4tgg5 was severely repressed. When grown in Murashiege & Skoog (MS) medium or in soil with sufficient water, Col-0 had the shortest roots, and tgg4tgg5 had the longest roots, while tgg4E8 and tgg5E12 had intermediate root lengths. In contrast, when grown in soil with excessive water, Col-0 had the longest roots, and tgg4tgg5 had the shortest roots. These results suggested that AtTGG4 and AtTGG5 regulated root growth and had a role in flood tolerance. The auxin-indicator gene DR5::GUS was then introduced into tgg4tgg5 by cross-pollination. DR5::GUS expression patterns in seedlings of F1, F2, and F3 generations indicated that AtTGG4 and AtTGG5 contributed to auxin biosynthesis in roots. The proposed mechanism is that

  14. Joint genetic and network analyses identify loci associated with root growth under NaCl stress in Arabidopsis thaliana.

    Science.gov (United States)

    Kobayashi, Yuriko; Sadhukhan, Ayan; Tazib, Tanveer; Nakano, Yuki; Kusunoki, Kazutaka; Kamara, Mohamed; Chaffai, Radhouane; Iuchi, Satoshi; Sahoo, Lingaraj; Kobayashi, Masatomo; Hoekenga, Owen A; Koyama, Hiroyuki

    2016-04-01

    Plants have evolved a series of tolerance mechanisms to saline stress, which perturbs physiological processes throughout the plant. To identify genetic mechanisms associated with salinity tolerance, we performed linkage analysis and genome-wide association study (GWAS) on maintenance of root growth of Arabidopsis thaliana in hydroponic culture with weak and severe NaCl toxicity. The top 200 single-nucleotide polymorphisms (SNPs) determined by GWAS could cumulatively explain approximately 70% of the variation observed at each stress level. The most significant SNPs were linked to the genes of ATP-binding cassette B10 and vacuolar proton ATPase A2. Several known salinity tolerance genes such as potassium channel KAT1 and calcium sensor SOS3 were also linked to SNPs in the top 200. In parallel, we constructed a gene co-expression network to independently verify that particular groups of genes work together to a common purpose. We identify molecular mechanisms to confer salt tolerance from both predictable and novel physiological sources and validate the utility of combined genetic and network analysis. Additionally, our study indicates that the genetic architecture of salt tolerance is responsive to the severity of stress. These gene datasets are a significant information resource for a following exploration of gene function. PMID:26667381

  15. Auxin regulates distal stem cell differentiation in Arabidopsis roots

    OpenAIRE

    Ding, Zhaojun; Friml, Jiří

    2010-01-01

    The stem cell niche in the root meristem is critical for the development of the plant root system. The plant hormone auxin acts as a versatile trigger in many developmental processes, including the regulation of root growth, but its role in the control of the stem cell activity remains largely unclear. Here we show that local auxin levels, determined by biosynthesis and intercellular transport, mediate maintenance or differentiation of distal stem cells in the Arabidopsis thaliana roots. Gene...

  16. Natural variation in small molecule-induced TIR-NB-LRR signaling induces root growth arrest via EDS1- and PAD4-complexed R protein VICTR in Arabidopsis.

    Science.gov (United States)

    Kim, Tae-Houn; Kunz, Hans-Henning; Bhattacharjee, Saikat; Hauser, Felix; Park, Jiyoung; Engineer, Cawas; Liu, Amy; Ha, Tracy; Parker, Jane E; Gassmann, Walter; Schroeder, Julian I

    2012-12-01

    In a chemical genetics screen we identified the small-molecule [5-(3,4-dichlorophenyl)furan-2-yl]-piperidine-1-ylmethanethione (DFPM) that triggers rapid inhibition of early abscisic acid signal transduction via PHYTOALEXIN DEFICIENT4 (PAD4)- and ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1)-dependent immune signaling mechanisms. However, mechanisms upstream of EDS1 and PAD4 in DFPM-mediated signaling remain unknown. Here, we report that DFPM generates an Arabidopsis thaliana accession-specific root growth arrest in Columbia-0 (Col-0) plants. The genetic locus responsible for this natural variant, VICTR (VARIATION IN COMPOUND TRIGGERED ROOT growth response), encodes a TIR-NB-LRR (for Toll-Interleukin1 Receptor-nucleotide binding-Leucine-rich repeat) protein. Analyses of T-DNA insertion victr alleles showed that VICTR is necessary for DFPM-induced root growth arrest and inhibition of abscisic acid-induced stomatal closing. Transgenic expression of the Col-0 VICTR allele in DFPM-insensitive Arabidopsis accessions recapitulated the DFPM-induced root growth arrest. EDS1 and PAD4, both central regulators of basal resistance and effector-triggered immunity, as well as HSP90 chaperones and their cochaperones RAR1 and SGT1B, are required for the DFPM-induced root growth arrest. Salicylic acid and jasmonic acid signaling pathway components are dispensable. We further demonstrate that VICTR associates with EDS1 and PAD4 in a nuclear protein complex. These findings show a previously unexplored association between a TIR-NB-LRR protein and PAD4 and identify functions of plant immune signaling components in the regulation of root meristematic zone-targeted growth arrest. PMID:23275581

  17. Involvement of Arabidopsis thaliana phospholipase Dzeta2 in root hydrotropism through the suppression of root gravitropism.

    OpenAIRE

    Taniguchi, Yukimi Y; Taniguchi, Masatoshi; Tsuge, Tomohiko; Oka, Atsuhiro; Aoyama, Takashi

    2010-01-01

    Root hydrotropism is the phenomenon of directional root growth toward moisture under water-deficient conditions. Although physiological and genetic studies have revealed the involvement of the root cap in the sensing of moisture gradients, and those of auxin and abscisic acid (ABA) in the signal transduction for asymmetric root elongation, the overall mechanism of root hydrotropism is still unclear. We found that the promoter activity of the Arabidopsis phospholipase Dzeta2 gene (PLDzeta2) wa...

  18. Cellular and molecular insight into the inhibition of primary root growth of Arabidopsis induced by peptaibols, a class of linear peptide antibiotics mainly produced by Trichoderma spp.

    Science.gov (United States)

    Shi, Wei-Ling; Chen, Xiu-Lan; Wang, Li-Xia; Gong, Zhi-Ting; Li, Shuyu; Li, Chun-Long; Xie, Bin-Bin; Zhang, Wei; Shi, Mei; Li, Chuanyou; Zhang, Yu-Zhong; Song, Xiao-Yan

    2016-04-01

    Trichodermaspp. are well known biocontrol agents that produce a variety of antibiotics. Peptaibols are a class of linear peptide antibiotics mainly produced byTrichoderma Alamethicin, the most studied peptaibol, is reported as toxic to plants at certain concentrations, while the mechanisms involved are unclear. We illustrated the toxic mechanisms of peptaibols by studying the growth-inhibitory effect of Trichokonin VI (TK VI), a peptaibol fromTrichoderma longibrachiatumSMF2, onArabidopsisprimary roots. TK VI inhibited root growth by suppressing cell division and cell elongation, and disrupting root stem cell niche maintenance. TK VI increased auxin content and disrupted auxin response gradients in root tips. Further, we screened theArabidopsisTK VI-resistant mutanttkr1tkr1harbors a point mutation inGORK, which encodes gated outwardly rectifying K(+)channel proteins. This mutation alleviated TK VI-induced suppression of K(+)efflux in roots, thereby stabilizing the auxin gradient. Thetkr1mutant also resisted the phytotoxicity of alamethicin. Our results indicate that GORK channels play a key role in peptaibol-plant interaction and that there is an inter-relationship between GORK channels and maintenance of auxin homeostasis. The cellular and molecular insight into the peptaibol-induced inhibition of plant root growth advances our understanding ofTrichoderma-plant interactions. PMID:26850879

  19. Spatiotemporal relationships between growth and microtubule orientation as revealed in living root cells of Arabidopsis thaliana transformed with green-fluorescent-protein gene construct GFP-MBD

    Science.gov (United States)

    Granger, C. L.; Cyr, R. J.

    2001-01-01

    Arabidopsis thaliana plants were transformed with GFP-MBD (J. Marc et al., Plant Cell 10: 1927-1939, 1998) under the control of a constitutive (35S) or copper-inducible promoter. GFP-specific fluorescence distributions, levels, and persistence were determined and found to vary with age, tissue type, transgenic line, and individual plant. With the exception of an increased frequency of abnormal roots of 35S GFP-MBD plants grown on kanamycin-containing media, expression of GFP-MBD does not appear to affect plant phenotype. The number of leaves, branches, bolts, and siliques as well as overall height, leaf size, and seed set are similar between wild-type and transgenic plants as is the rate of root growth. Thus, we conclude that the transgenic plants can serve as a living model system in which the dynamic behavior of microtubules can be visualized. Confocal microscopy was used to simultaneously monitor growth and microtubule behavior within individual cells as they passed through the elongation zone of the Arabidopsis root. Generally, microtubules reoriented from transverse to oblique or longitudinal orientations as growth declined. Microtubule reorientation initiated at the ends of the cell did not necessarily occur simultaneously in adjacent neighboring cells and did not involve complete disintegration and repolymerization of microtubule arrays. Although growth rates correlated with microtubule reorientation, the two processes were not tightly coupled in terms of their temporal relationships, suggesting that other factor(s) may be involved in regulating both events. Additionally, microtubule orientation was more defined in cells whose growth was accelerating and less stringent in cells whose growth was decelerating, indicating that microtubule-orienting factor(s) may be sensitive to growth acceleration, rather than growth per se.

  20. Strigolactones suppress adventitious rooting in Arabidopsis and pea.

    Science.gov (United States)

    Rasmussen, Amanda; Mason, Michael Glenn; De Cuyper, Carolien; Brewer, Philip B; Herold, Silvia; Agusti, Javier; Geelen, Danny; Greb, Thomas; Goormachtig, Sofie; Beeckman, Tom; Beveridge, Christine Anne

    2012-04-01

    Adventitious root formation is essential for the propagation of many commercially important plant species and involves the formation of roots from nonroot tissues such as stems or leaves. Here, we demonstrate that the plant hormone strigolactone suppresses adventitious root formation in Arabidopsis (Arabidopsis thaliana) and pea (Pisum sativum). Strigolactone-deficient and response mutants of both species have enhanced adventitious rooting. CYCLIN B1 expression, an early marker for the initiation of adventitious root primordia in Arabidopsis, is enhanced in more axillary growth2 (max2), a strigolactone response mutant, suggesting that strigolactones restrain the number of adventitious roots by inhibiting the very first formative divisions of the founder cells. Strigolactones and cytokinins appear to act independently to suppress adventitious rooting, as cytokinin mutants are strigolactone responsive and strigolactone mutants are cytokinin responsive. In contrast, the interaction between the strigolactone and auxin signaling pathways in regulating adventitious rooting appears to be more complex. Strigolactone can at least partially revert the stimulatory effect of auxin on adventitious rooting, and auxin can further increase the number of adventitious roots in max mutants. We present a model depicting the interaction of strigolactones, cytokinins, and auxin in regulating adventitious root formation. PMID:22323776

  1. Arabidopsis Myrosinase Genes AtTGG4 and AtTGG5 Are Root-Tip Specific and Contribute to Auxin Biosynthesis and Root-Growth Regulation

    OpenAIRE

    Lili Fu; Meng Wang; Bingying Han; Deguan Tan; Xuepiao Sun; Jiaming Zhang

    2016-01-01

    Plant myrosinases (β-thioglucoside glucohydrolases) are classified into two subclasses, Myr I and Myr II. The biological function of Myr I has been characterized as a major biochemical defense against insect pests and pathogens in cruciferous plants. However, the biological function of Myr II remains obscure. We studied the function of two Myr II member genes AtTGG4 and AtTGG5 in Arabidopsis. RT-PCR showed that both genes were specifically expressed in roots. GUS-assay revealed that both gene...

  2. Identification and characterization of Arabidopsis AtNUDX9 as a GDP-d-mannose pyrophosphohydrolase: its involvement in root growth inhibition in response to ammonium

    OpenAIRE

    Tanaka, Hiroyuki; Maruta, Takanori; Ogawa, Takahisa; Tanabe, Noriaki; Tamoi, Masahiro; Yoshimura, Kazuya; Shigeoka, Shigeru

    2015-01-01

    Highlight AtNUDX9, a GDP-d-Man pyrophosphohydrolase in Arabidopsis, is involved in the regulation of GDP-d-Man levels affecting ammonium sensitivity via modulation of protein N-glycosylation in the roots.

  3. Arabidopsis: An Adequate Model for Dicot Root Systems?

    OpenAIRE

    Zobel, Richard W.

    2016-01-01

    The Arabidopsis root system is frequently considered to have only three classes of root: primary, lateral, and adventitious. Research with other plant species has suggested up to eight different developmental/functional classes of root for a given plant root system. If Arabidopsis has only three classes of root, it may not be an adequate model for eudicot plant root systems. Recent research, however, can be interpreted to suggest that pre-flowering Arabidopsis does have at least five (5) of t...

  4. Identification of MicroRNA 395a in 24-Epibrassinolide-Regulated Root Growth of Arabidopsis thaliana Using MicroRNA Arrays

    Directory of Open Access Journals (Sweden)

    Hsueh-Fen Juan

    2013-07-01

    Full Text Available Brassinosteroids (BRs are endogenous plant hormones and are essential for normal plant growth and development. MicroRNAs (miRNAs of Arabidopsis thaliana are involved in mediating cell proliferation in leaves, stress tolerance, and root development. The specifics of BR mechanisms involving miRNAs are unknown. Using customized miRNA array analysis, we identified miRNAs from A. thaliana ecotype Columbia (Col-0 regulated by 24-epibrassinolide (EBR, a highly active BR. We found that miR395a was significantly up-regulated by EBR treatment and validated its expression under these conditions. miR395a was over expressed in leaf veins and root tissues in EBR-treated miR395a promoter::GUS plants. We integrated bioinformatics methods and publicly available DNA microarray data to predict potential targets of miR395a. GUN5—a multifunctional protein involved in plant metabolic functions such as chlorophyll synthesis and the abscisic acid (ABA pathway—was identified as a possible target. ABI4 and ABI5, both genes positively regulated by ABA, were down-regulated by EBR treatment. In summary, our results suggest that EBR regulates seedling development and root growth of A. thaliana through miR395a by suppressing GUN5 expression and its downstream signal transduction.

  5. Ethylene Inhibits Cell Proliferation of the Arabidopsis Root Meristem.

    Science.gov (United States)

    Street, Ian H; Aman, Sitwat; Zubo, Yan; Ramzan, Aleena; Wang, Xiaomin; Shakeel, Samina N; Kieber, Joseph J; Schaller, G Eric

    2015-09-01

    The root system of plants plays a critical role in plant growth and survival, with root growth being dependent on both cell proliferation and cell elongation. Multiple phytohormones interact to control root growth, including ethylene, which is primarily known for its role in controlling root cell elongation. We find that ethylene also negatively regulates cell proliferation at the root meristem of Arabidopsis (Arabidopsis thaliana). Genetic analysis indicates that the inhibition of cell proliferation involves two pathways operating downstream of the ethylene receptors. The major pathway is the canonical ethylene signal transduction pathway that incorporates CONSTITUTIVE TRIPLE RESPONSE1, ETHYLENE INSENSITIVE2, and the ETHYLENE INSENSITIVE3 family of transcription factors. The secondary pathway is a phosphorelay based on genetic analysis of receptor histidine kinase activity and mutants involving the type B response regulators. Analysis of ethylene-dependent gene expression and genetic analysis supports SHORT HYPOCOTYL2, a repressor of auxin signaling, as one mediator of the ethylene response and furthermore, indicates that SHORT HYPOCOTYL2 is a point of convergence for both ethylene and cytokinin in negatively regulating cell proliferation. Additional analysis indicates that ethylene signaling contributes but is not required for cytokinin to inhibit activity of the root meristem. These results identify key elements, along with points of cross talk with cytokinin and auxin, by which ethylene negatively regulates cell proliferation at the root apical meristem. PMID:26149574

  6. Piriformospora indica Stimulates Root Metabolism of Arabidopsis thaliana.

    Science.gov (United States)

    Strehmel, Nadine; Mönchgesang, Susann; Herklotz, Siska; Krüger, Sylvia; Ziegler, Jörg; Scheel, Dierk

    2016-01-01

    Piriformospora indica is a root-colonizing fungus, which interacts with a variety of plants including Arabidopsis thaliana. This interaction has been considered as mutualistic leading to growth promotion of the host. So far, only indolic glucosinolates and phytohormones have been identified as key players. In a comprehensive non-targeted metabolite profiling study, we analyzed Arabidopsis thaliana's roots, root exudates, and leaves of inoculated and non-inoculated plants by ultra performance liquid chromatography/electrospray ionization quadrupole-time-of-flight mass spectrometry (UPLC/(ESI)-QTOFMS) and gas chromatography/electron ionization quadrupole mass spectrometry (GC/EI-QMS), and identified further biomarkers. Among them, the concentration of nucleosides, dipeptides, oligolignols, and glucosinolate degradation products was affected in the exudates. In the root profiles, nearly all metabolite levels increased upon co-cultivation, like carbohydrates, organic acids, amino acids, glucosinolates, oligolignols, and flavonoids. In the leaf profiles, we detected by far less significant changes. We only observed an increased concentration of organic acids, carbohydrates, ascorbate, glucosinolates and hydroxycinnamic acids, and a decreased concentration of nitrogen-rich amino acids in inoculated plants. These findings contribute to the understanding of symbiotic interactions between plant roots and fungi of the order of Sebacinales and are a valid source for follow-up mechanistic studies, because these symbioses are particular and clearly different from interactions of roots with mycorrhizal fungi or dark septate endophytes. PMID:27399695

  7. Loss of membrane fluidity and endocytosis inhibition are involved in rapid aluminum-induced root growth cessation in Arabidopsis thaliana

    Czech Academy of Sciences Publication Activity Database

    Krtková, J.; Havelková, L.; Křepelová, A.; Fišer, R.; Vosolsobě, S.; Novotná, Z.; Martinec, Jan; Schwarzerová, K.

    2012-01-01

    Roč. 60, Nov 2012 (2012), s. 88-97. ISSN 0981-9428 R&D Projects: GA ČR GA522/05/0340 Grant ostatní: GA ČR(CZ) GPP207/12/P890 Institutional research plan: CEZ:AV0Z50380511 Keywords : Aluminum toxicity * Arabidopsis thaliana * Cortical microtubules Subject RIV: ED - Physiology Impact factor: 2.775, year: 2012

  8. SDG2-Mediated H3K4 Methylation Is Required for Proper Arabidopsis Root Growth and Development

    OpenAIRE

    Xiaozhen Yao; Haiyang Feng; Yu Yu; Aiwu Dong; Wen-Hui Shen

    2013-01-01

    Trithorax group (TrxG) proteins are evolutionarily conserved in eukaryotes and play critical roles in transcriptional activation via deposition of histone H3 lysine 4 trimethylation (H3K4me3) in chromatin. Several Arabidopsis TrxG members have been characterized, and among them SET DOMAIN GROUP 2 (SDG2) has been shown to be necessary for global genome-wide H3K4me3 deposition. Although pleiotropic phenotypes have been uncovered in the sdg2 mutants, SDG2 function in the regulation of stem cell ...

  9. Intraspecific competition reveals conditional fitness effects of single gene polymorphism at the Arabidopsis root growth regulator BRX

    OpenAIRE

    Shindo, Chikako; Bernasconi, Giorgina; Hardtke, Christian S

    2009-01-01

    • Intraspecific genetic variation for morphological traits is observed in many organisms. In Arabidopsis thaliana, alleles responsible for intraspecific morphological variation are increasingly being identified. However, the fitness consequences remain unclear in most cases. • Here, the fitness effects of alleles of the BRX gene are investigated. A brx loss-of-function allele, which was found in a natural accession, results in a highly branched but poorly elongated root system. • Comparison ...

  10. Capturing Arabidopsis Root Architecture Dynamics with root-fit Reveals Diversity in Responses to Salinity1[W][OPEN

    Science.gov (United States)

    Julkowska, Magdalena M.; Hoefsloot, Huub C.J.; Mol, Selena; Feron, Richard; de Boer, Gert-Jan; Haring, Michel A.; Testerink, Christa

    2014-01-01

    The plant root is the first organ to encounter salinity stress, but the effect of salinity on root system architecture (RSA) remains elusive. Both the reduction in main root (MR) elongation and the redistribution of the root mass between MRs and lateral roots (LRs) are likely to play crucial roles in water extraction efficiency and ion exclusion. To establish which RSA parameters are responsive to salt stress, we performed a detailed time course experiment in which Arabidopsis (Arabidopsis thaliana) seedlings were grown on agar plates under different salt stress conditions. We captured RSA dynamics with quadratic growth functions (root-fit) and summarized the salt-induced differences in RSA dynamics in three growth parameters: MR elongation, average LR elongation, and increase in number of LRs. In the ecotype Columbia-0 accession of Arabidopsis, salt stress affected MR elongation more severely than LR elongation and an increase in LRs, leading to a significantly altered RSA. By quantifying RSA dynamics of 31 different Arabidopsis accessions in control and mild salt stress conditions, different strategies for regulation of MR and LR meristems and root branching were revealed. Different RSA strategies partially correlated with natural variation in abscisic acid sensitivity and different Na+/K+ ratios in shoots of seedlings grown under mild salt stress. Applying root-fit to describe the dynamics of RSA allowed us to uncover the natural diversity in root morphology and cluster it into four response types that otherwise would have been overlooked. PMID:25271266

  11. Effects of natural and synthetic auxins on the gravitropic growth habit of roots in two auxin-resistant mutants of Arabidopsis, axr1 and axr4: evidence for defects in the auxin influx mechanism of axr4

    Science.gov (United States)

    Yamamoto, M.; Yamamoto, K. T.

    1999-01-01

    The partially agravitropic growth habit of roots of an auxin-resistant mutant of Arabidopsis thaliana, axr4, was restored by the addition of 30-300 nM 1-naphthaleneacetic acid (NAA) to the growth medium. Neither indole 3-acetic acid (IAA) nor 2,4-dichlorophenoxyacetic acid (2,4-D) showed such an effect. Growth of axr4 roots was resistant to IAA and 2,4-D, but not at all to NAA. The differential effects of the three auxins suggest that the defects of axr4 result from a lower auxin influx into its cells. The partially agravitropic growth habit of axr1 roots, which was less severe than that of axr4 roots, was only slightly affected by the three auxins in the growth medium at concentrations up to 300 nM; growth of axr1 roots was resistant to all three of the auxins. These results suggest that the lesion of axrl mutants is different from that of axr4.

  12. Natural genetic variation in Arabidopsis for responsiveness to plant growth-promoting rhizobacteria

    OpenAIRE

    Wintermans, P.C.A.; Bakker, P.A.H.M.; Pieterse, C.M.J.

    2016-01-01

    The plant growth-promoting rhizobacterium (PGPR) Pseudomonas simiae WCS417r stimulates lateral root formation and increases shoot growth in Arabidopsis thaliana (Arabidopsis). These plant growth-stimulating effects are partly caused by volatile organic compounds (VOCs) produced by the bacterium. Here, we performed a genome-wide association (GWA) study on natural genetic variation in Arabidopsis for the ability to profit from rhizobacteria-mediated plant growth-promotion. To this end, 302 Arab...

  13. Natural genetic variation in Arabidopsis for responsiveness to plant growth-promoting rhizobacteria

    NARCIS (Netherlands)

    Wintermans, P.C.A.; Bakker, P.A.H.M.; Pieterse, C.M.J.

    2016-01-01

    The plant growth-promoting rhizobacterium (PGPR) Pseudomonas simiae WCS417r stimulates lateral root formation and increases shoot growth in Arabidopsis thaliana (Arabidopsis). These plant growth-stimulating effects are partly caused by volatile organic compounds (VOCs) produced by the bacterium. Her

  14. miR390, Arabidopsis TAS3 tasiRNAs, and Their AUXIN RESPONSE FACTOR Targets Define an Autoregulatory Network Quantitatively Regulating Lateral Root Growth[W

    Science.gov (United States)

    Marin, Elena; Jouannet, Virginie; Herz, Aurélie; Lokerse, Annemarie S.; Weijers, Dolf; Vaucheret, Herve; Nussaume, Laurent; Crespi, Martin D.; Maizel, Alexis

    2010-01-01

    Plants adapt to different environmental conditions by constantly forming new organs in response to morphogenetic signals. Lateral roots branch from the main root in response to local auxin maxima. How a local auxin maximum translates into a robust pattern of gene activation ensuring the proper growth of the newly formed lateral root is largely unknown. Here, we demonstrate that miR390, TAS3-derived trans-acting short-interfering RNAs (tasiRNAs), and AUXIN RESPONSE FACTORS (ARFs) form an auxin-responsive regulatory network controlling lateral root growth. Spatial expression analysis using reporter gene fusions, tasi/miRNA sensors, and mutant analysis showed that miR390 is specifically expressed at the sites of lateral root initiation where it triggers the biogenesis of tasiRNAs. These tasiRNAs inhibit ARF2, ARF3, and ARF4, thus releasing repression of lateral root growth. In addition, ARF2, ARF3, and ARF4 affect auxin-induced miR390 accumulation. Positive and negative feedback regulation of miR390 by ARF2, ARF3, and ARF4 thus ensures the proper definition of the miR390 expression pattern. This regulatory network maintains ARF expression in a concentration range optimal for specifying the timing of lateral root growth, a function similar to its activity during leaf development. These results also show how small regulatory RNAs integrate with auxin signaling to quantitatively regulate organ growth during development. PMID:20363771

  15. Glycerol Affects Root Development through Regulation of Multiple Pathways in Arabidopsis

    OpenAIRE

    Jun Hu; Yonghong Zhang; Jinfang Wang; Yongming Zhou

    2014-01-01

    Glycerol metabolism has been well studied biochemically. However, the means by which glycerol functions in plant development is not well understood. This study aimed to investigate the mechanism underlying the effects of glycerol on root development in Arabidopsis thaliana. Exogenous glycerol inhibited primary root growth and altered lateral root development in wild-type plants. These phenotypes appeared concurrently with increased endogenous glycerol-3-phosphate (G3P) and H2O2 contents in se...

  16. “Rhizoponics”: a novel hydroponic rhizotron for root system analyses on mature Arabidopsis thaliana plants

    OpenAIRE

    Mathieu, Laura; Lobet, Guillaume; Tocquin, Pierre; Périlleux, Claire

    2015-01-01

    Background Well-developed and functional roots are critical to support plant life and reach high crop yields. Their study however, is hampered by their underground growth and characterizing complex root system architecture (RSA) therefore remains a challenge. In the last few years, several phenotyping methods, including rhizotrons and x-ray computed tomography, have been developed for relatively thick roots. But in the model plant Arabidopsis thaliana, in vitro culture remains the easiest and...

  17. Effects of elevated carbon dioxide and sucrose concentrations on Arabidopsis thaliana root architecture and anatomy

    International Nuclear Information System (INIS)

    Plant root growth is known to be influenced by higher levels of atmospheric carbon dioxide (CO2). Roots of some species grown in hydroponics under elevated CO2 concentrations may be more competitive sinks for photosynthetic assimilates than roots grown under lower CO2 conditions. Root branching patterns may also be influenced by elevated CO2 concentrations. Studies have also shown that factors such as soil compaction, salinity and the availability of nitrate, phosphorous, oxygen and water also influence root growth, and the effects of higher CO2 on roots can be confounded by such environmental factors. This study evaluated the effects of elevated carbon dioxide and sucrose concentrations on Arabidopsis thaliana root growth, morphology, and architecture. Both ambient and elevated CO2 levels were used along with various sucrose concentrations. The study revealed that A. thaliana plants grown on a phytagar medium in small chambers with elevated CO2 had longer roots, more lateral root growth than plants grown in ambient CO2. Roots in elevated CO2 were found to have wider root diameters, and more secondary growth. The addition of sucrose to the media closely resembled the effects of elevated CO2. In addition, the increase in sucrose concentration had a bigger effect on root morphology under ambient, than elevated CO2. Therefore, both elevated CO2 and increased sucrose concentrations promote root growth by increasing their number, length, and diameter. The dichotomy branching index (DBI) also dropped resulting in a more dichotomous branching pattern. 34 refs., 5 figs

  18. The click-compatible sugar 6-deoxy-alkynyl glucose metabolically incorporates into Arabidopsis root hair tips and arrests their growth.

    Science.gov (United States)

    McClosky, Daniel D; Wang, Bo; Chen, Gong; Anderson, Charles T

    2016-03-01

    Plant cell walls are dynamic structures whose polysaccharide components are rearranged and recycled during growth and morphogenesis. Covalent fluorescent tagging of these polysaccharides following a metabolic labeling approach can help elucidate these changes. Herein reported are the synthesis and seedling-incorporation of a plant polysaccharide chemical reporter, 6-deoxy-alkynyl glucose (6dAG), that is modeled on D-glucose. Whereas fucose-alkyne, a previously reported chemical reporter for pectin, incorporates diffusely throughout growing cell walls, 6dAG incorporated specifically into root hair tips. This incorporation occurs in a time- and concentration-dependent manner. 6dAG exposure both induces and colocalizes with callose deposition in this tissue, and arrests both root hair and root growth. These results show that plants can incorporate an additional alkynyl-modified sugar analog into their metabolism, and into a discrete subcellular location. PMID:26833385

  19. The secretion of the bacterial phytase PHY-US417 by Arabidopsis roots reveals its potential for increasing phosphate acquisition and biomass production during co-growth.

    Science.gov (United States)

    Belgaroui, Nibras; Berthomieu, Pierre; Rouached, Hatem; Hanin, Moez

    2016-09-01

    Phytic acid (PA) is a major source of inorganic phosphate (Pi) in the soil; however, the plant lacks the capacity to utilize it for Pi nutrition and growth. Microbial phytases constitute a group of enzymes that are able to remobilize Pi from PA. Thus, the use of these phytases to increase the capacity of higher plants to remobilize Pi from PA is of agronomical interest. In the current study, we generate transgenic Arabidopsis lines (ePHY) overexpressing an extracellular form of the phytase PHY-US417 of Bacillus subtilis, which are characterized by high levels of secreted phytase activity. In the presence of PA as sole source of Pi, while the wild-type plants show hallmark of Pi deficiency phenotypes, including the induction of the expression of Pi starvation-induced genes (PSI, e.g. PHT1;4) and the inhibition of growth capacity, the ePHY overexpressing lines show a higher biomass production and no PSI induction. Interestingly, when co-cultured with ePHY overexpressors, wild-type Arabidopsis plants (or tobacco) show repression of the PSI genes, improvement of Pi content and increases in biomass production. In line with these results, mutants in the high-affinity Pi transporters, namely pht1;1 and pht1;1-1;4, both fail to accumulate Pi and to grow when co-cultured with ePHY overexpressors. Taken together, these data demonstrate the potential of secreted phytases in improving the Pi content and enhancing growth of not only the transgenic lines but also the neighbouring plants. PMID:26914451

  20. Statistical modeling of nitrogen-dependent modulation of root system architecture in Arabidopsis thaliana

    Institute of Scientific and Technical Information of China (English)

    Takao Araya; Takuya Kubo; Nicolaus von Wiren; Hideki Takahashi

    2016-01-01

    Plant root development is strongly affected by nutrient availability. Despite the importance of structure and function of roots in nutrient acquisition, statistical modeling approaches to evaluate dynamic and temporal modulations of root system architecture in response to nutrient availability have remained as widely open and exploratory areas in root biology. In this study, we developed a statistical modeling approach to investigate modulations of root system archi-tecture in response to nitrogen availability. Mathematical models were designed for quantitative assessment of root growth and root branching phenotypes and their dynamic relationships based on hierarchical configuration of primary and lateral roots formulating the fishbone-shaped root system architecture in Arabidopsis thaliana. Time-series datasets reporting dynamic changes in root developmental traits on different nitrate or ammonium concentrations were gener-ated for statistical analyses. Regression analyses unraveled key parameters associated with:(i) inhibition of primary root growth under nitrogen limitation or on ammonium;(i ) rapid progression of lateral root emergence in response to ammonium; and (i i) inhibition of lateral root elongation in the presence of excess nitrate or ammonium. This study provides a statistical framework for interpreting dynamic modulation of root system architecture, supported by meta-analysis of datasets displaying morphological responses of roots to diverse nitrogen supplies.

  1. Regulation of Arabidopsis root development by small signaling peptides

    Directory of Open Access Journals (Sweden)

    Christina eDelay

    2013-09-01

    Full Text Available Plant root systems arise de novo from a single embryonic root. Complex and highly coordinated developmental networks are required to ensure the formation of lateral organs maximises plant fitness. The Arabidopsis root is well suited to dissection of regulatory and developmental networks due to its highly ordered, predictable structure. A myriad of regulatory signalling networks control the development of plant roots, from the classical hormones such as auxin and cytokinin to short-range positional signalling molecules that relay information between neighbouring cells. Small signaling peptides are a growing class of regulatory molecules involved in many aspects of root development including meristem maintenance, the gravitropic response, lateral root development and vascular formation. Here, recent findings on the roles of regulatory peptides in these aspects of root development are discussed.

  2. Overexpression of the cytosolic cytokinin oxidase/dehydrogenase (CKX7) from Arabidopsis causes specific changes in root growth and xylem differentiation

    Czech Academy of Sciences Publication Activity Database

    Kollmer, I.; Novák, Ondřej; Strnad, Miroslav; Schmülling, T.; Werner, T.

    2014-01-01

    Roč. 78, č. 3 (2014), s. 359-371. ISSN 0960-7412 Institutional support: RVO:61389030 Keywords : xylem differentiation * Arabidopsis thaliana * cytokinin oxidase/dehydrogenase Subject RIV: ED - Physiology Impact factor: 5.972, year: 2014

  3. Effects of elevated carbon dioxide and sucrose concentrations on Arabidopsis thaliana root architecture and anatomy

    Energy Technology Data Exchange (ETDEWEB)

    Lee-Ho, E.; Walton, L.J.; Reid, D.M.; Yeung, E.C.; Kurepin, L.V. [Calgary Univ., AB (Canada). Dept. of Biology

    2007-03-15

    Plant root growth is known to be influenced by higher levels of atmospheric carbon dioxide (CO{sub 2}). Roots of some species grown in hydroponics under elevated CO{sub 2} concentrations may be more competitive sinks for photosynthetic assimilates than roots grown under lower CO{sub 2} conditions. Root branching patterns may also be influenced by elevated CO{sub 2} concentrations. Studies have also shown that factors such as soil compaction, salinity and the availability of nitrate, phosphorous, oxygen and water also influence root growth, and the effects of higher CO{sub 2} on roots can be confounded by such environmental factors. This study evaluated the effects of elevated carbon dioxide and sucrose concentrations on Arabidopsis thaliana root growth, morphology, and architecture. Both ambient and elevated CO{sub 2} levels were used along with various sucrose concentrations. The study revealed that A. thaliana plants grown on a phytagar medium in small chambers with elevated CO{sub 2} had longer roots, more lateral root growth than plants grown in ambient CO{sub 2}. Roots in elevated CO{sub 2} were found to have wider root diameters, and more secondary growth. The addition of sucrose to the media closely resembled the effects of elevated CO{sub 2}. In addition, the increase in sucrose concentration had a bigger effect on root morphology under ambient, than elevated CO{sub 2}. Therefore, both elevated CO{sub 2} and increased sucrose concentrations promote root growth by increasing their number, length, and diameter. The dichotomy branching index (DBI) also dropped resulting in a more dichotomous branching pattern. 34 refs., 5 figs.

  4. The bZIP Protein VIP1 Is Involved in Touch Responses in Arabidopsis Roots.

    Science.gov (United States)

    Tsugama, Daisuke; Liu, Shenkui; Takano, Tetsuo

    2016-06-01

    VIP1 is a bZIP transcription factor in Arabidopsis (Arabidopsis thaliana). VIP1 transiently accumulates in the nucleus when cells are exposed to hypoosmotic conditions, but its physiological relevance is unclear. This is possibly because Arabidopsis has approximately 10 close homologs of VIP1 and they function redundantly. To examine their physiological roles, transgenic plants overexpressing a repression domain-fused form of VIP1 (VIP1-SRDXox plants), in which the gene activation mediated by VIP1 is expected to be repressed, were generated. Because hypoosmotic stress can mimic mechanical stimuli (e.g. touch), the touch-induced root-waving phenotypes and gene expression patterns in those transgenic plants were examined. VIP1-SRDXox plants exhibited more severe root waving and lower expression of putative VIP1 target genes. The expression of the VIP1-green fluorescent protein (GFP) fusion protein partially suppressed the VIP1-SRDX-induced increase in root waving when expressed in the VIP1-SRDXox plants. These results suggest that VIP1 can suppress the touch-induced root waving. The VIP1-SRDX-induced increase in root waving was also suppressed when the synthetic auxin 2,4-dichlorophenoxy acetic acid or the ethylene precursor 1-aminocyclopropane-1-carboxylic acid, which is known to activate auxin biosynthesis, was present in the growth medium. Root cap cells with the auxin marker DR5rev::GFP were more abundant in the VIP1-SRDXox background than in the wild-type background. Auxin is transported via the root cap, and the conditions of outermost root cap layers were abnormal in VIP1-SRDXox plants. These results raise the possibility that VIP1 influences structures of the root cap and thereby regulates the local auxin responses in roots. PMID:27208231

  5. Evaluation of herbicide potential of sesquiterpene lactone and flavonoid: impact on germination, seedling growth indices and root length in arabidopsis thaliana

    International Nuclear Information System (INIS)

    Plants produce a vast array of natural products that mediate their interaction with the environment. Artemisinin is important sesquiterpene lactones, mostly isolated from the Artemisia annua plant, has a wide range of biological activities, including insecticidal, antibacterial and antifungal, antifeedants, and allelopathic properties. Flavonoids (rutin) have attracted attention, primarily as natural antioxidants, and many are allelopathic agents, commonly present in Fagopyrum esculentum Moench. In the present study, phytotoxic effect of artemisinin and rutin on germination and seedling growth of Arabidopsis thaliana were tested under controlled bioassays. Total germination % age was reduced in A. thaliana after treatment with artemisinin at 10, 20, 40, 80, 160 meu M concentration; while maximum reduction in germination %age was observed at highest concentrations of 160 and 80 meu M. Rutin at 100, 250, 500, 750 and 1000 mM concentration decreased germination % age in A. thaliana but the concentration 1000 mM proved to be most deleterious. Artemisinin at 10, 50, 40, 80, 160 mM concentration inhibited the speed of germination (S) of A. thaliana. Similarly, Rutin-delayed the A. thaliana S at all the concentration tested and maximum inhibition was recorded at 1000 mM concentration. The effect of artemisinin and rutin on radicle length (RL) of A. thaliana was concentration dependent. There was a gradual decrease in RL of A. thaliana due to rutin at all concentration. Seedling vigour index (SVI) of A. thaliana was decreased after treatment with both artemisinin and rutin at all concentration while the maximum reduction was observed at highest concentration tested. (author)

  6. Natural genetic variation in Arabidopsis for responsiveness to plant growth-promoting rhizobacteria.

    Science.gov (United States)

    Wintermans, Paul C A; Bakker, Peter A H M; Pieterse, Corné M J

    2016-04-01

    The plant growth-promoting rhizobacterium (PGPR) Pseudomonas simiae WCS417r stimulates lateral root formation and increases shoot growth in Arabidopsis thaliana (Arabidopsis). These plant growth-stimulating effects are partly caused by volatile organic compounds (VOCs) produced by the bacterium. Here, we performed a genome-wide association (GWA) study on natural genetic variation in Arabidopsis for the ability to profit from rhizobacteria-mediated plant growth-promotion. To this end, 302 Arabidopsis accessions were tested for root architecture characteristics and shoot fresh weight in response to exposure to WCS417r. Although virtually all Arabidopsis accessions tested responded positively to WCS417r, there was a large variation between accessions in the increase in shoot fresh weight, the extra number of lateral roots formed, and the effect on primary root length. Correlation analyses revealed that the bacterially-mediated increase in shoot fresh weight is related to alterations in root architecture. GWA mapping for WCS417r-stimulated changes in root and shoot growth characteristics revealed 10 genetic loci highly associated with the responsiveness of Arabidopsis to the plant growth-promoting activity of WCS417r. Several of the underlying candidate genes have been implicated in important plant growth-related processes. These results demonstrate that plants possess natural genetic variation for the capacity to profit from the plant growth-promoting function of a beneficial rhizobacterium in their rhizosphere. This knowledge is a promising starting point for sustainable breeding strategies for future crops that are better able to maximize profitable functions from their root microbiome. PMID:26830772

  7. Water Deficit Enhances C Export to the Roots in Arabidopsis thaliana Plants with Contribution of Sucrose Transporters in Both Shoot and Roots.

    Science.gov (United States)

    Durand, Mickaël; Porcheron, Benoît; Hennion, Nils; Maurousset, Laurence; Lemoine, Rémi; Pourtau, Nathalie

    2016-03-01

    Root high plasticity is an adaptation to its changing environment. Water deficit impairs growth, leading to sugar accumulation in leaves, part of which could be available to roots via sucrose (Suc) phloem transport. Phloem loading is widely described in Arabidopsis (Arabidopsis thaliana), while unloading in roots is less understood. To gain information on leaf-to-root transport, a soil-based culture system was developed to monitor root system architecture in two dimensions. Under water deficit (50% of soil water-holding capacity), total root length was strongly reduced but the depth of root foraging and the shape of the root system were less affected, likely to improve water uptake. (14)CO2 pulse-chase experiments confirmed that water deficit enhanced carbon (C) export to the roots, as suggested by the increased root-to-shoot ratio. The transcript levels of AtSWEET11 (for sugar will eventually be exported transporter), AtSWEET12, and AtSUC2 (for Suc carrier) genes, all three involved in Suc phloem loading, were significantly up-regulated in leaves of water deficit plants, in accordance with the increase in C export from the leaves to the roots. Interestingly, the transcript levels of AtSUC2 and AtSWEET11 to AtSWEET15 were also significantly higher in stressed roots, underlying the importance of Suc apoplastic unloading in Arabidopsis roots and a putative role for these Suc transporters in Suc unloading. These data demonstrate that, during water deficit, plants respond to growth limitation by allocating relatively more C to the roots to maintain an efficient root system and that a subset of Suc transporters is potentially involved in the flux of C to and in the roots. PMID:26802041

  8. Piriformospora indica antagonizes cyst nematode infection and development in Arabidopsis roots

    OpenAIRE

    Daneshkhah, R.; Cabello, S.; Rozanska, E.; Sobczak, M.; Grundler, F. M. W.; Wieczorek, K.; Hofmann, J.

    2013-01-01

    The beneficial endophytic fungus Piriformospora indica colonizes the roots of many plant species, including the model plant Arabidopsis thaliana. Its colonization promotes plant growth, development, and seed production as well as resistance to various biotic and abiotic stresses. In the present work, P. indica was tested as potential antagonist of the sedentary plant-parasitic nematode Heterodera schachtii. This biotrophic cyst-forming nematode induces severe host plant damage by changing the...

  9. Regulation of stem cell maintenance and cell differentiation states in Arabidopsis root development

    OpenAIRE

    Luijten, M.

    2009-01-01

    The experiments presented in this thesis topic the role of transcription factor family members in regulating growth, development, and maintenance of the Arabidopsis root. We demonstrate a conserved homeobox transcription factor regulates distal stem cell maintenance and expand the notion that the PLETHORA (PLT) family of transcription factors specifically regulates stem cell properties to a significantly broader role. In addition, we show that members of the PLT gene family can activate trans...

  10. Cytokinin-dependent secondary growth determines root biomass in radish (Raphanus sativus L.)

    OpenAIRE

    Jang, Geupil; Lee, Jung-Hun; Rastogi, Khushboo; Park, Suhyoung; Oh, Sang-Hun; Lee, Ji-Young

    2015-01-01

    Highlight Comparative studies using Arabidopsis and radish (Raphanus sativus) found that cytokinin-mediated regulatory programmes in the cambium are important for the radial growth of radish roots and its variations.

  11. Shoot-supplied ammonium targets the root auxin influx carrier AUX1 and inhibits lateral root emergence in Arabidopsis

    KAUST Repository

    Li, Baohai

    2011-03-24

    Deposition of ammonium (NH4 +) from the atmosphere is a substantial environmental problem. While toxicity resulting from root exposure to NH4 + is well studied, little is known about how shoot-supplied ammonium (SSA) affects root growth. In this study, we show that SSA significantly affects lateral root (LR) development. We show that SSA inhibits lateral root primordium (LRP) emergence, but not LRP initiation, resulting in significantly impaired LR number. We show that the inhibition is independent of abscisic acid (ABA) signalling and sucrose uptake in shoots but relates to the auxin response in roots. Expression analyses of an auxin-responsive reporter, DR5:GUS, and direct assays of auxin transport demonstrated that SSA inhibits root acropetal (rootward) auxin transport while not affecting basipetal (shootward) transport or auxin sensitivity of root cells. Mutant analyses indicated that the auxin influx carrier AUX1, but not the auxin efflux carriers PIN-FORMED (PIN)1 or PIN2, is required for this inhibition of LRP emergence and the observed auxin response. We found that AUX1 expression was modulated by SSA in vascular tissues rather than LR cap cells in roots. Taken together, our results suggest that SSA inhibits LRP emergence in Arabidopsis by interfering with AUX1-dependent auxin transport from shoot to root. © 2011 Blackwell Publishing Ltd.

  12. In Vitro Morphogenesis of Arabidopsis to Search for Novel Endophytic Fungi Modulating Plant Growth.

    Directory of Open Access Journals (Sweden)

    Francesco Dovana

    Full Text Available Fungal endophytes have shown to affect plant growth and to confer stress tolerance to the host; however, effects of endophytes isolated from water plants have been poorly investigated. In this study, fungi isolated from stems (stem-E and roots (root-E of Mentha aquatica L. (water mint were identified, and their morphogenetic properties analysed on in vitro cultured Arabidopsis (L. Heynh., 14 and 21 days after inoculation (DAI. Nineteen fungi were analysed and, based on ITS analysis, 17 isolates showed to be genetically distinct. The overall effect of water mint endophytes on Arabidopsis fresh (FW and dry weight (DW was neutral and positive, respectively, and the increased DW, mainly occurring 14 DAI, was possibly related to plant defence mechanism. Only three fungi increased both FW and DW of Arabidopsis at 14 and 21 DAI, thus behaving as plant growth promoting (PGP fungi. E-treatment caused a reduction of root depth and primary root length in most cases and inhibition-to-promotion of root area and lateral root length, from 14 DAI. Only Phoma macrostoma, among the water mint PGP fungi, increased both root area and depth, 21 DAI. Root depth and area 14 DAI were shown to influence DWs, indicating that the extension of the root system, and thus nutrient uptake, was an important determinant of plant dry biomass. Reduction of Arabidopsis root depth occurred to a great extent when plants where treated with stem-E while root area decreased or increased under the effects of stem-E and root-E, respectively, pointing to an influence of the endophyte origin on root extension. M. aquatica and many other perennial hydrophytes have growing worldwide application in water pollution remediation. The present study provided a model for directed screening of endophytes able to modulate plant growth in the perspective of future field applications of these fungi.

  13. Constitutive salicylic acid accumulation in pi4kIII beta 1 beta 2 Arabidopsis plants stunts rosette but not root growth

    Czech Academy of Sciences Publication Activity Database

    Šašek, Vladimír; Janda, Martin; Delage, E.; Puyaubert, J.; Guivarc'h, A.; Maseda, Encarnación López; Dobrev, Petre; Caius, J.; Valentová, O.; Burketová, Lenka; Zachowski, A.; Ruelland, E.

    2014-01-01

    Roč. 203, č. 3 (2014), s. 805-816. ISSN 0028-646X R&D Projects: GA ČR(CZ) GAP501/11/1654 Institutional support: RVO:61389030 Keywords : Arabidopsis * dwarf phenotype * hormone transduction Subject RIV: CE - Biochemistry Impact factor: 7.672, year: 2014

  14. Quiescent center initiation in the Arabidopsis lateral root primordia is dependent on the SCARECROW transcription factor.

    Science.gov (United States)

    Goh, Tatsuaki; Toyokura, Koichi; Wells, Darren M; Swarup, Kamal; Yamamoto, Mayuko; Mimura, Tetsuro; Weijers, Dolf; Fukaki, Hidehiro; Laplaze, Laurent; Bennett, Malcolm J; Guyomarc'h, Soazig

    2016-09-15

    Lateral root formation is an important determinant of root system architecture. In Arabidopsis, lateral roots originate from pericycle cells, which undergo a program of morphogenesis to generate a new lateral root meristem. Despite its importance for root meristem organization, the onset of quiescent center (QC) formation during lateral root morphogenesis remains unclear. Here, we used live 3D confocal imaging to monitor cell organization and identity acquisition during lateral root development. Our dynamic observations revealed an early morphogenesis phase and a late meristem formation phase as proposed in the bi-phasic growth model. Establishment of lateral root QCs coincided with this developmental phase transition. QC precursor cells originated from the outer layer of stage II lateral root primordia, within which the SCARECROW (SCR) transcription factor was specifically expressed. Disrupting SCR function abolished periclinal divisions in this lateral root primordia cell layer and perturbed the formation of QC precursor cells. We conclude that de novo QC establishment in lateral root primordia operates via SCR-mediated formative cell division and coincides with the developmental phase transition. PMID:27510971

  15. Ethylene modulates flavonoid accumulation and gravitropic responses in roots of Arabidopsis.

    Science.gov (United States)

    Buer, Charles S; Sukumar, Poornima; Muday, Gloria K

    2006-04-01

    Plant organs change their growth direction in response to reorientation relative to the gravity vector. We explored the role of ethylene in Arabidopsis (Arabidopsis thaliana) root gravitropism. Treatment of wild-type Columbia seedlings with the ethylene precursor 1-aminocyclopropane carboxylic acid (ACC) reduced root elongation and gravitropic curvature. The ethylene-insensitive mutants ein2-5 and etr1-3 had wild-type root gravity responses, but lacked the growth and gravity inhibition by ACC found in the wild type. We examined the effect of ACC on tt4(2YY6) seedlings, which have a null mutation in the gene encoding chalcone synthase, the first enzyme in flavonoid synthesis. The tt4(2YY6) mutant makes no flavonoids, has elevated indole-3-acetic acid transport, and exhibits a delayed gravity response. Roots of tt4(2YY6), the backcrossed line tt4-2, and two other tt4 alleles had wild-type sensitivity to growth inhibition by ACC, whereas the root gravitropic curvature of these tt4 alleles was much less inhibited by ACC than wild-type roots, suggesting that ACC may reduce gravitropic curvature by altering flavonoid synthesis. ACC treatment induced flavonoid accumulation in root tips, as judged by a dye that becomes fluorescent upon binding flavonoids in wild type, but not in ein2-5 and etr1-3. ACC also prevented a transient peak in flavonoid synthesis in response to gravity. Together, these experiments suggest that elevated ethylene levels negatively regulate root gravitropism, using EIN2- and ETR1-dependent pathways, and that ACC inhibition of gravity response occurs through altering flavonoid synthesis. PMID:16489132

  16. An auxin-responsive endogenous peptide regulates root development in Arabidopsis

    Institute of Scientific and Technical Information of China (English)

    Fengxi Yang; Yu Song; Hao Yang; Zhibin Liu; Genfa Zhu; Yi Yang

    2014-01-01

    Auxin plays critical roles in root formation and development. The components involved in this process, however, are not well understood. Here, we newly identified a peptide encoding gene, auxin-responsive endogenous polypeptide 1 (AREP1), which is induced by auxin, and mediates root development in Arabidopsis. Expression of AREP1 was specific to the cotyledon and to root and shoot meristem tissues. Amounts of AREP1 transcripts and AREP1-green fluorescent protein fusion proteins were elevated in response to indoleacetic acid treatment. Suppression of AREP1 through RNAi silencing resulted in reduction of primary root length, increase of lateral root number, and expansion of adventitious roots, compared to the observations in wild-type plants in the presence of auxin. By contrast, transgenic plants overexpressing AREP1 showed enhanced growth of the primary root under auxin treatment. Additionally, rootmorphology, including lateral root number and adventitious roots, differed greatly between transgenic and wildtype plants. Further analysis indicated that the expression of auxin-responsive genes, such as IAA3, IAA7, IAA17, GH3.2, GH3.3, and SAUR-AC1, was significantly higher in AREP1 RNAi plants, and was slightly lower in AREP1 overexpressing plants than in wildtype plants. These results suggest that the novel endogenous peptide AREP1 plays an important role in the process of auxinmediated root development.

  17. Signaling in Arabidopsis roots in response to beneficial rhizobacteria

    OpenAIRE

    Zamioudis, C.

    2012-01-01

    Root colonization by selected strains of beneficial soil-resident bacteria is known to improve plant growth, influence root system architecture and trigger a systemic immune response that is effective against a broad range of pathogens, known as induced systemic resistance (ISR). In this thesis we explore signaling mechanisms that are activated in the roots in response to ISR-inducing bacteria. We demonstrate that the plant growth-promoting rhizobacterium Pseudomonas fluorescens WCS417 secret...

  18. In Vitro Morphogenesis of Arabidopsis to Search for Novel Endophytic Fungi Modulating Plant Growth

    OpenAIRE

    Francesco Dovana; Marco Mucciarelli; Maurizio Mascarello; Anna Fusconi

    2015-01-01

    Fungal endophytes have shown to affect plant growth and to confer stress tolerance to the host; however, effects of endophytes isolated from water plants have been poorly investigated. In this study, fungi isolated from stems (stem-E) and roots (root-E) of Mentha aquatica L. (water mint) were identified, and their morphogenetic properties analysed on in vitro cultured Arabidopsis (L.) Heynh., 14 and 21 days after inoculation (DAI). Nineteen fungi were analysed and, based on ITS analysis, 17 i...

  19. Dysfunctional mitochondria regulate the size of root apical meristem and leaf development in Arabidopsis

    Science.gov (United States)

    Hsieh, Wei-Yu; Liao, Jo-Chien; Hsieh, Ming-Hsiun

    2015-01-01

    Mitochondria play an important role in maintaining metabolic and energy homeostasis in the plant cell. Thus, perturbation of mitochondrial structure and function will affect plant growth and development. Arabidopsis slow growth3 (slo3) is defective in At3g61360 that encodes a pentatricopeptide repeat (PPR) protein. Analysis of slo3 mitochondrial RNA metabolism revealed that the splicing of nad7 intron 2 is impaired, which leads to a dramatic reduction in complex I activity. So the SLO3 PPR protein is a splicing factor that is required for the removal of nad7 intron 2 in Arabidopsis. The slo3 mutant plants have obvious phenotypes with severe growth retardation and delayed development. The size of root apical meristem (RAM) is reduced and the production of meristem cells is decreased in slo3. Furthermore, the rosette leaves of slo3 are curled or crinkled, which may be derived from uneven growth of the leaf surface. The underlying mechanisms by which dysfunctional mitochondria affect these growth and developmental phenotypes have yet to be established. Nonetheless, plant hormone auxin is known to play an important role in orchestrating the development of RAM and leaf shape. It is possible that dysfunctional mitochondria may interact with auxin signaling pathways to regulate the boundary of RAM and the cell division arrest front during leaf growth in Arabidopsis. PMID:26237004

  20. Hormonal response and root architecture in Arabidopsis thaliana subjected to heavy metals

    Directory of Open Access Journals (Sweden)

    Antonella Vitti

    2014-05-01

    Full Text Available In this work, specific concentrations of cadmium, copper and zinc in double combination, were supplied for 12 days to growing seedlings of the model species Arabidopsis thaliana. Metal accumulation was measured in roots and shoots. Microscopic analyses revealed that root morphology was affected by metals, and that the root and shoot levels of indole-3-acetic acid, trans-zeatin riboside and dihydrozeatin riboside varied accordingly. Minor modifications in gibberellic acid levels occurred in the Zinc treatments, whereas abscisic acid level did not change after the exposition to metals. Reverse transcription polymerase chain reaction analysis of some genes involved in auxin and cytokinin synthesis (AtAAO, AtNIT and AtIPT revealed that their expression were not affected by metal treatments. The root morphological alterations that resulted in an increased surface area, due to the formation of root hairs and lateral roots, could be signs of the response to metal stress in terms of a functionally-addressed reorientation of root growth. The root system plasticity observed could be important for better understanding the manner in which the root architecture is shaped by environmental and hormonal stimuli.

  1. Integrating roots into a whole plant network of flowering time genes in Arabidopsis thaliana.

    Science.gov (United States)

    Bouché, Frédéric; D'Aloia, Maria; Tocquin, Pierre; Lobet, Guillaume; Detry, Nathalie; Périlleux, Claire

    2016-01-01

    Molecular data concerning the involvement of roots in the genetic pathways regulating floral transition are lacking. In this study, we performed global analyses of the root transcriptome in Arabidopsis in order to identify flowering time genes that are expressed in the roots and genes that are differentially expressed in the roots during the induction of flowering. Data mining of public microarray experiments uncovered that about 200 genes whose mutations are reported to alter flowering time are expressed in the roots (i.e. were detected in more than 50% of the microarrays). However, only a few flowering integrator genes passed the analysis cutoff. Comparison of root transcriptome in short days and during synchronized induction of flowering by a single 22-h long day revealed that 595 genes were differentially expressed. Enrichment analyses of differentially expressed genes in root tissues, gene ontology categories, and cis-regulatory elements converged towards sugar signaling. We concluded that roots are integrated in systemic signaling, whereby carbon supply coordinates growth at the whole plant level during the induction of flowering. This coordination could involve the root circadian clock and cytokinin biosynthesis as a feed forward loop towards the shoot. PMID:27352932

  2. Cyclic programmed cell death stimulates hormone signaling and root development in Arabidopsis

    NARCIS (Netherlands)

    Xuan, Wei; Band, Leah R.; Kumpf, Robert P.; Rybel, De Bert

    2016-01-01

    The plant root cap, surrounding the very tip of the growing root, perceives and transmits environmental signals to the inner root tissues. In Arabidopsis thaliana, auxin released by the root cap contributes to the regular spacing of lateral organs along the primary root axis. Here, we show that t

  3. Recent Advances in Understanding the Molecular Mechanisms Regulating the Root System Response to Phosphate Deficiency in Arabidopsis.

    Science.gov (United States)

    Bouain, Nadia; Doumas, Patrick; Rouached, Hatem

    2016-08-01

    Phosphorus (P) is an essential macronutrient for plant growth and development. Inorganic phosphate (Pi) is the major form of P taken up from the soil by plant roots. It is well established that under Pi deficiency condition, plant roots undergo striking morphological changes; mainly a reduction in primary root length while increase in lateral root length as well as root hair length and density. This typical phenotypic change reflects complex interactions with other nutrients such as iron, and involves the activity of a large spectrum of plant hormones. Although, several key proteins involved in the regulation of root growth under Pi-deficiency have been identified in Arabidopsis, how plants adapt roots system architecture in response to Pi availability remains an open question. In the current post-genomic era, state of the art technologies like high-throughput phenotyping and sequencing platforms,"omics" methods, together with the widespread use of system biology and genome-wide association studies will help to elucidate the genetic architectures of root growth on different Pi regimes. It is clear that the large-scale characterization of molecular systems will improve our understanding of nutrient stress phenotype and biology. Herein, we summarize the recent advances and future directions towards a better understanding of Arabidopsis root developmental programs functional under Pi deficiency. Such a progress is necessary to devise strategies to improve the Pi use efficiency in plants that is an important issue for agriculture. PMID:27499680

  4. Profiling of secondary metabolites in root exudates of Arabidopsis thaliana.

    Science.gov (United States)

    Strehmel, Nadine; Böttcher, Christoph; Schmidt, Stephan; Scheel, Dierk

    2014-12-01

    To explore the chemical composition of root exudates of the model plant Arabidopsis thaliana a workflow for nontargeted metabolite profiling of the semipolar fraction of root exudates was developed. It comprises hydroponic plant cultivation and sampling of root exudates under sterile conditions, sample preparation by solid-phase extraction and analysis by reversed-phase UPLC/ESI-QTOFMS. Following the established workflow, root exudates of six-week-old plants were profiled and a set of reproducibly occurring molecular features was compiled. To structurally elucidate the corresponding metabolites, accurate mass tandem mass spectrometry and on-line hydrogen/deuterium exchange were applied. Currently, a total of 103 compounds were detected and annotated by elemental composition of which more than 90 were structurally characterized or classified. Among them, 42 compounds were rigorously identified using an authenticated standard. The compounds identified so far include nucleosides, deoxynucleosides, aromatic amino acids, anabolites and catabolites of glucosinolates, dipeptides, indolics, salicylic and jasmonic acid catabolites, coumarins, mono-, di- and trilignols, hydroxycinnamic acid derivatives and oxylipins and exemplify the high chemical diversity of plant root exudates. PMID:25457500

  5. Systems analysis of transcriptome data provides new hypotheses about Arabidopsis root response to nitrate treatments

    Directory of Open Access Journals (Sweden)

    Javier eCanales

    2014-02-01

    Full Text Available Nitrogen (N is an essential macronutrient for plant growth and development. Plants adapt to changes in N availability partly by changes in global gene expression. We integrated publicly available root microarray data under contrasting nitrate conditions to identify new genes and functions important for adaptive nitrate responses in Arabidopsis thaliana roots. Overall, more than two thousand genes exhibited changes in expression in response to nitrate treatments in Arabidopsis thaliana root organs. Global regulation of gene expression by nitrate depends largely on the experimental context. However, despite significant differences from experiment to experiment in the identity of regulated genes, there is a robust nitrate response of specific biological functions. Integrative gene network analysis uncovered relationships between nitrate-responsive genes and eleven highly co-expressed gene clusters (modules. Four of these gene network modules have robust nitrate responsive functions such as transport, signaling and metabolism. Network analysis hypothesized G2-like transcription factors are key regulatory factors controlling transport and signaling functions. Our meta-analysis highlights the role of biological processes not studied before in the context of the nitrate response such as root hair development and provides testable hypothesis to advance our understanding of nitrate responses in plants.

  6. Hypoxia up-regulates mitochondrial genome-encoded transcripts in Arabidopsis roots.

    Science.gov (United States)

    Hameed, Muhammad Waqar

    2016-04-28

    Plants are frequently exposed to limitations in oxygen availability during their lifetime. During evolution, they have developed a number of physiological and morphological adaptations to tolerate oxygen and other stress conditions. These include regulation of growth by gene expression and ATP generation. The regulation of nuclear genes after hypoxia and anoxia is well studied; however, the regulation of mitochondrial genes in response to oxygen stress has not been characterized to date. Therefore, we have established an Arabidopsis mitochondrial genome-specific microarray that accommodates probes for all mitochondrial DNA-encoded genes and conserved open reading frames. Our analysis showed an up-regulation of mitochondrial transcripts in Arabidopsis roots after 48 h of hypoxia. Since no significant difference was detected in the expression of mitochondrial RNA polymerases or the mitochondrial DNA content per cell, we propose a transcriptional mode of induction of mitochondrial gene expression under hypoxia. PMID:27002184

  7. ABA-mediated ROS in mitochondria regulate root meristem activity by controlling PLETHORA expression in Arabidopsis.

    Directory of Open Access Journals (Sweden)

    Li Yang

    2014-12-01

    Full Text Available Although research has determined that reactive oxygen species (ROS function as signaling molecules in plant development, the molecular mechanism by which ROS regulate plant growth is not well known. An aba overly sensitive mutant, abo8-1, which is defective in a pentatricopeptide repeat (PPR protein responsible for the splicing of NAD4 intron 3 in mitochondrial complex I, accumulates more ROS in root tips than the wild type, and the ROS accumulation is further enhanced by ABA treatment. The ABO8 mutation reduces root meristem activity, which can be enhanced by ABA treatment and reversibly recovered by addition of certain concentrations of the reducing agent GSH. As indicated by low ProDR5:GUS expression, auxin accumulation/signaling was reduced in abo8-1. We also found that ABA inhibits the expression of PLETHORA1 (PLT1 and PLT2, and that root growth is more sensitive to ABA in the plt1 and plt2 mutants than in the wild type. The expression of PLT1 and PLT2 is significantly reduced in the abo8-1 mutant. Overexpression of PLT2 in an inducible system can largely rescue root apical meristem (RAM-defective phenotype of abo8-1 with and without ABA treatment. These results suggest that ABA-promoted ROS in the mitochondria of root tips are important retrograde signals that regulate root meristem activity by controlling auxin accumulation/signaling and PLT expression in Arabidopsis.

  8. HAWAIIAN SKIRT regulates the quiescent center-independent meristem activity in Arabidopsis roots.

    Science.gov (United States)

    Kim, Eun-Sol; Choe, Goh; Sebastian, Jose; Ryu, Kook Hui; Mao, Linyong; Fei, Zhangjun; Lee, Ji-Young

    2016-06-01

    Root apical meristem (RAM) drives post-embryonic root growth by constantly supplying cells through mitosis. It is composed of stem cells and their derivatives, the transit-amplifying (TA) cells. Stem cell organization and its maintenance in the RAM are well characterized, however, their relationships with TA cells remain unclear. SHORTROOT (SHR) is critical for root development. It patterns cell types and promotes the post-embryonic root growth. Defective root growth in the shr has been ascribed to the lack of quiescent center (QC), which maintains the surrounding stem cells. However, our recent investigation indicated that SHR maintains TA cells independently of QC by modulating PHABULOSA (PHB) through miRNA165/6. PHB controls TA cell activity by modulating cytokinin levels and type B Arabidopsis Response Regulator activity, in a dosage-dependent manner. To further understand TA cell regulation, we conducted a shr suppressor screen. With an extensive mutagenesis screen followed by genome sequencing of a pooled F2 population, we discovered two suppressor alleles with mutations in HAWAIIAN SKIRT (HWS). HWS, encoding an F-box protein with kelch domain, is expressed, partly depending on SHR, in the root cap and in the pericycle of the differentiation zone. Interestingly, root growth in the shr hws was more active than the wild-type roots for the first 7 days after germination, without recovering QC. Contrary to shr phb, shr hws did not show a recovery of cytokinin signaling. These indicate that HWS affects QC-independent TA cell activities through a pathway distinctive from PHB. PMID:26968317

  9. Proteomic alterations in root tips of Arabidopsis thaliana seedlings under altered gravity conditions

    Science.gov (United States)

    Zheng, H. Q.; Wang, H.

    Gravity has a profound influence on plant growth and development Removed the influence of gravitational acceleration by spaceflight caused a wide range of cellular changes in plant Whole seedling that germinated and grown on clinostats showed the absent of gravitropism At the cellular level clinostat treatment has specific effects on plant cells such as induce alterations in cell wall composition increase production of heat-soluble proteins impact on the cellular energy metabolism facilitate a uniform distribution of plastids amyloplasts and increase number and volume of nucleoli A number of recent studies have shown that the exposure of Arabidopsis seedlings and callus cells to gravity stimulation hyper g-forces or clinostat rotation induces alterations in gene expression In our previous study the proteome of the Arabidopsis thaliana callus cells were separated by high resolution two-dimensional electrophoresis 2-DE Image analysis revealed that 80 protein spots showed quantitative and qualitative variations after exposure to clinostat rotation treatment We report here a systematic proteomic approach to investigate the altered gravity responsive proteins in root tip of Arabidopsis thaliana cv Landsberg erecta Three-day-old seedlings were exposed for 12h to a horizontal clinostat rotation H simulated weightlessness altered g-forces by centrifugation 7g hypergravity a vertical clinostat rotation V clinostat control or a stationary control grown conditions Total proteins of roots were extracted

  10. Arabidopsis Growth Simulation Using Image Processing Technology

    Directory of Open Access Journals (Sweden)

    Junmei Zhang

    2014-01-01

    Full Text Available This paper aims to provide a method to represent the virtual Arabidopsis plant at each growth stage. It includes simulating the shape and providing growth parameters. The shape is described with elliptic Fourier descriptors. First, the plant is segmented from the background with the chromatic coordinates. With the segmentation result, the outer boundary series are obtained by using boundary tracking algorithm. The elliptic Fourier analysis is then carried out to extract the coefficients of the contour. The coefficients require less storage than the original contour points and can be used to simulate the shape of the plant. The growth parameters include total area and the number of leaves of the plant. The total area is obtained with the number of the plant pixels and the image calibration result. The number of leaves is derived by detecting the apex of each leaf. It is achieved by using wavelet transform to identify the local maximum of the distance signal between the contour points and the region centroid. Experiment result shows that this method can record the growth stage of Arabidopsis plant with fewer data and provide a visual platform for plant growth research.

  11. Bacterial communities associated with the leaves and the roots of Arabidopsis thaliana.

    Directory of Open Access Journals (Sweden)

    Natacha Bodenhausen

    Full Text Available Diverse communities of bacteria inhabit plant leaves and roots and those bacteria play a crucial role for plant health and growth. Arabidopsis thaliana is an important model to study plant pathogen interactions, but little is known about its associated bacterial community under natural conditions. We used 454 pyrosequencing to characterize the bacterial communities associated with the roots and the leaves of wild A. thaliana collected at 4 sites; we further compared communities on the outside of the plants with communities in the endophytic compartments. We found that the most heavily sequenced bacteria in A. thaliana associated community are related to culturable species. Proteobacteria, Actinobacteria, and Bacteroidetes are the most abundant phyla in both leaf and root samples. At the genus level, sequences of Massilia and Flavobacterium are prevalent in both samples. Organ (leaf vs root and habitat (epiphytes vs endophytes structure the community. In the roots, richness is higher in the epiphytic communities compared to the endophytic compartment (P = 0.024, while the reverse is true for the leaves (P = 0.032. Interestingly, leaf and root endophytic compartments do not differ in richness, diversity and evenness, while they differ in community composition (P = 0.001. The results show that although the communities associated with leaves and roots share many bacterial species, the associated communities differ in structure.

  12. Cell Wall Heterogeneity in Root Development of Arabidopsis.

    Science.gov (United States)

    Somssich, Marc; Khan, Ghazanfar Abbas; Persson, Staffan

    2016-01-01

    Plant cell walls provide stability and protection to plant cells. During growth and development the composition of cell walls changes, but provides enough strength to withstand the turgor of the cells. Hence, cell walls are highly flexible and diverse in nature. These characteristics are important during root growth, as plant roots consist of radial patterns of cells that have diverse functions and that are at different developmental stages along the growth axis. Young stem cell daughters undergo a series of rapid cell divisions, during which new cell walls are formed that are highly dynamic, and that support rapid anisotropic cell expansion. Once the cells have differentiated, the walls of specific cell types need to comply with and support different cell functions. For example, a newly formed root hair needs to be able to break through the surrounding soil, while endodermal cells modify their walls at distinct positions to form Casparian strips between them. Hence, the cell walls are modified and rebuilt while cells transit through different developmental stages. In addition, the cell walls of roots readjust to their environment to support growth and to maximize nutrient uptake. Many of these modifications are likely driven by different developmental and stress signaling pathways. However, our understanding of how such pathways affect cell wall modifications and what enzymes are involved remain largely unknown. In this review we aim to compile data linking cell wall content and re-modeling to developmental stages of root cells, and dissect how root cell walls respond to certain environmental changes. PMID:27582757

  13. Beneficial Bacteria Isolated from Grapevine Inner Tissues Shape Arabidopsis thaliana Roots.

    Science.gov (United States)

    Baldan, Enrico; Nigris, Sebastiano; Romualdi, Chiara; D'Alessandro, Stefano; Clocchiatti, Anna; Zottini, Michela; Stevanato, Piergiorgio; Squartini, Andrea; Baldan, Barbara

    2015-01-01

    We investigated the potential plant growth-promoting traits of 377 culturable endophytic bacteria, isolated from Vitis vinifera cv. Glera, as good biofertilizer candidates in vineyard management. Endophyte ability in promoting plant growth was assessed in vitro by testing ammonia production, phosphate solubilization, indole-3-acetic acid (IAA) and IAA-like molecule biosynthesis, siderophore and lytic enzyme secretion. Many of the isolates were able to mobilize phosphate (33%), release ammonium (39%), secrete siderophores (38%) and a limited part of them synthetized IAA and IAA-like molecules (5%). Effects of each of the 377 grapevine beneficial bacteria on Arabidopsis thaliana root development were also analyzed to discern plant growth-promoting abilities (PGP) of the different strains, that often exhibit more than one PGP trait. A supervised model-based clustering analysis highlighted six different classes of PGP effects on root architecture. A. thaliana DR5::GUS plantlets, inoculated with IAA-producing endophytes, resulted in altered root growth and enhanced auxin response. Overall, the results indicate that the Glera PGP endospheric culturable microbiome could contribute, by structural root changes, to obtain water and nutrients increasing plant adaptation and survival. From the complete cultivable collection, twelve promising endophytes mainly belonging to the Bacillus but also to Micrococcus and Pantoea genera, were selected for further investigations in the grapevine host plants towards future application in sustainable management of vineyards. PMID:26473358

  14. Beneficial Bacteria Isolated from Grapevine Inner Tissues Shape Arabidopsis thaliana Roots.

    Directory of Open Access Journals (Sweden)

    Enrico Baldan

    Full Text Available We investigated the potential plant growth-promoting traits of 377 culturable endophytic bacteria, isolated from Vitis vinifera cv. Glera, as good biofertilizer candidates in vineyard management. Endophyte ability in promoting plant growth was assessed in vitro by testing ammonia production, phosphate solubilization, indole-3-acetic acid (IAA and IAA-like molecule biosynthesis, siderophore and lytic enzyme secretion. Many of the isolates were able to mobilize phosphate (33%, release ammonium (39%, secrete siderophores (38% and a limited part of them synthetized IAA and IAA-like molecules (5%. Effects of each of the 377 grapevine beneficial bacteria on Arabidopsis thaliana root development were also analyzed to discern plant growth-promoting abilities (PGP of the different strains, that often exhibit more than one PGP trait. A supervised model-based clustering analysis highlighted six different classes of PGP effects on root architecture. A. thaliana DR5::GUS plantlets, inoculated with IAA-producing endophytes, resulted in altered root growth and enhanced auxin response. Overall, the results indicate that the Glera PGP endospheric culturable microbiome could contribute, by structural root changes, to obtain water and nutrients increasing plant adaptation and survival. From the complete cultivable collection, twelve promising endophytes mainly belonging to the Bacillus but also to Micrococcus and Pantoea genera, were selected for further investigations in the grapevine host plants towards future application in sustainable management of vineyards.

  15. Exploring Arabidopsis thaliana Root Endophytes via Single-Cell Genomics

    Energy Technology Data Exchange (ETDEWEB)

    Lundberg, Derek; Woyke, Tanja; Tringe, Susannah; Dangl, Jeff

    2014-03-19

    Land plants grow in association with microbial communities both on their surfaces and inside the plant (endophytes). The relationships between microbes and their host can vary from pathogenic to mutualistic. Colonization of the endophyte compartment occurs in the presence of a sophisticated plant immune system, implying finely tuned discrimination of pathogens from mutualists and commensals. Despite the importance of the microbiome to the plant, relatively little is known about the specific interactions between plants and microbes, especially in the case of endophytes. The vast majority of microbes have not been grown in the lab, and thus one of the few ways of studying them is by examining their DNA. Although metagenomics is a powerful tool for examining microbial communities, its application to endophyte samples is technically difficult due to the presence of large amounts of host plant DNA in the sample. One method to address these difficulties is single-cell genomics where a single microbial cell is isolated from a sample, lysed, and its genome amplified by multiple displacement amplification (MDA) to produce enough DNA for genome sequencing. This produces a single-cell amplified genome (SAG). We have applied this technology to study the endophytic microbes in Arabidopsis thaliana roots. Extensive 16S gene profiling of the microbial communities in the roots of multiple inbred A. thaliana strains has identified 164 OTUs as being significantly enriched in all the root endophyte samples compared to their presence in bulk soil.

  16. Real-time Analysis of Lateral Root Organogenesis in Arabidopsis

    Science.gov (United States)

    Marhavý, Peter; Benková, Eva

    2016-01-01

    Plants maintain capacity to form new organs such as leaves, flowers, lateral shoots and roots throughout their postembryonic lifetime. Lateral roots (LRs) originate from a few pericycle cells that acquire attributes of founder cells (FCs), undergo series of anticlinal divisions, and give rise to a few short initial cells. After initiation, coordinated cell division and differentiation occur, giving rise to lateral root primordia (LRP). Primordia continue to grow, emerge through the cortex and epidermal layers of the primary root, and finally a new apical meristem is established taking over the responsibility for growth of mature lateral roots [for detailed description of the individual stages of lateral root organogenesis see Malamy and Benfey (1997)]. To examine this highly dynamic developmental process and to investigate a role of various hormonal, genetic and environmental factors in the regulation of lateral root organogenesis, the real time imaging based analyses represent extremely powerful tools (Laskowski et al., 2008; De Smet et al., 2012; Marhavý et al., 2013 and 2014). Herein, we describe a protocol for real time lateral root primordia (LRP) analysis, which enables the monitoring of an onset of the specific gene expression and subcellular protein localization during primordia organogenesis, as well as the evaluation of the impact of genetic and environmental perturbations on LRP organogenesis.

  17. Inference of the Genetic Network Regulating Lateral Root Initiation in Arabidopsis thaliana

    KAUST Repository

    Muraro, D.

    2013-01-01

    Regulation of gene expression is crucial for organism growth, and it is one of the challenges in systems biology to reconstruct the underlying regulatory biological networks from transcriptomic data. The formation of lateral roots in Arabidopsis thaliana is stimulated by a cascade of regulators of which only the interactions of its initial elements have been identified. Using simulated gene expression data with known network topology, we compare the performance of inference algorithms, based on different approaches, for which ready-to-use software is available. We show that their performance improves with the network size and the inclusion of mutants. We then analyze two sets of genes, whose activity is likely to be relevant to lateral root initiation in Arabidopsis, and assess causality of their regulatory interactions by integrating sequence analysis with the intersection of the results of the best performing methods on time series and mutants. The methods applied capture known interactions between genes that are candidate regulators at early stages of development. The network inferred from genes significantly expressed during lateral root formation exhibits distinct scale free, small world and hierarchical properties and the nodes with a high out-degree may warrant further investigation. © 2004-2012 IEEE.

  18. New theories of root growth modelling

    Science.gov (United States)

    Landl, Magdalena; Schnepf, Andrea; Vanderborght, Jan; Huber, Katrin; Javaux, Mathieu; Bengough, A. Glyn; Vereecken, Harry

    2016-04-01

    In dynamic root architecture models, root growth is represented by moving root tips whose line trajectory results in the creation of new root segments. Typically, the direction of root growth is calculated as the vector sum of various direction-affecting components. However, in our simulations this did not reproduce experimental observations of root growth in structured soil. We therefore developed a new approach to predict the root growth direction. In this approach we distinguish between, firstly, driving forces for root growth, i.e. the force exerted by the root which points in the direction of the previous root segment and gravitropism, and, secondly, the soil mechanical resistance to root growth or penetration resistance. The latter can be anisotropic, i.e. depending on the direction of growth, which leads to a difference between the direction of the driving force and the direction of the root tip movement. Anisotropy of penetration resistance can be caused either by microscale differences in soil structure or by macroscale features, including macropores. Anisotropy at the microscale is neglected in our model. To allow for this, we include a normally distributed random deflection angle α to the force which points in the direction of the previous root segment with zero mean and a standard deviation σ. The standard deviation σ is scaled, so that the deflection from the original root tip location does not depend on the spatial resolution of the root system model. Similarly to the water flow equation, the direction of the root tip movement corresponds to the water flux vector while the driving forces are related to the water potential gradient. The analogue of the hydraulic conductivity tensor is the root penetrability tensor. It is determined by the inverse of soil penetration resistance and describes the ease with which a root can penetrate the soil. By adapting the three dimensional soil and root water uptake model R-SWMS (Javaux et al., 2008) in this way

  19. Arabidopsis ABCG14 protein controls the acropetal translocation of root-synthesized cytokinins

    Science.gov (United States)

    Zhang, Kewei; Novak, Ondrej; Wei, Zhaoyang; Gou, Mingyue; Zhang, Xuebin; Yu, Yong; Yang, Huijun; Cai, Yuanheng; Strnad, Miroslav; Liu, Chang-Jun

    2014-02-01

    Cytokinins are a major group of phytohormones regulating plant growth, development and stress responses. However, in contrast to the well-defined polar transport of auxins, the molecular basis of cytokinin transport is poorly understood. Here we show that an ATP-binding cassette transporter in Arabidopsis, AtABCG14, is essential for the acropetal (root to shoot) translocation of the root-synthesized cytokinins. AtABCG14 is expressed primarily in the pericycle and stelar cells of roots. Knocking out AtABCG14 strongly impairs the translocation of trans-zeatin (tZ)-type cytokinins from roots to shoots, thereby affecting the plant’s growth and development. AtABCG14 localizes to the plasma membrane of transformed cells. In planta feeding of C14 or C13-labelled tZ suggests that it acts as an efflux pump and its presence in the cells directly correlates with the transport of the fed cytokinin. Therefore, AtABCG14 is a transporter likely involved in the long-distance translocation of cytokinins in planta.

  20. Glycerol affects root development through regulation of multiple pathways in Arabidopsis.

    Directory of Open Access Journals (Sweden)

    Jun Hu

    Full Text Available Glycerol metabolism has been well studied biochemically. However, the means by which glycerol functions in plant development is not well understood. This study aimed to investigate the mechanism underlying the effects of glycerol on root development in Arabidopsis thaliana. Exogenous glycerol inhibited primary root growth and altered lateral root development in wild-type plants. These phenotypes appeared concurrently with increased endogenous glycerol-3-phosphate (G3P and H2O2 contents in seedlings, and decreased phosphate levels in roots. Upon glycerol treatment, G3P level and root development did not change in glycerol kinase mutant gli1, but G3P level increased in gpdhc1 and fad-gpdh mutants, which resulted in more severely impaired root development. Overexpression of the FAD-GPDH gene attenuated the alterations in G3P, phosphate and H2O2 levels, leading to increased tolerance to exogenous glycerol, which suggested that FAD-GPDH plays an important role in modulating this response. Free indole-3-acetic acid (IAA content increased by 46%, and DR5pro::GUS staining increased in the stele cells of the root meristem under glycerol treatment, suggesting that glycerol likely alters normal auxin distribution. Decreases in PIN1 and PIN7 expression, β-glucuronidase (GUS staining in plants expressing PIN7pro::GUS and green fluorescent protein (GFP fluorescence in plants expressing PIN7pro::PIN7-GFP were observed, indicating that polar auxin transport in the root was downregulated under glycerol treatment. Analyses with auxin-related mutants showed that TIR1 and ARF7 were involved in regulating root growth under glycerol treatment. Glycerol-treated plants showed significant reductions in root meristem size and cell number as revealed by CYCB1;1pro::GUS staining. Furthermore, the expression of CDKA and CYCB1 decreased significantly in treated plants compared with control plants, implying possible alterations in cell cycle progression. Our data

  1. Glycerol affects root development through regulation of multiple pathways in Arabidopsis.

    Science.gov (United States)

    Hu, Jun; Zhang, Yonghong; Wang, Jinfang; Zhou, Yongming

    2014-01-01

    Glycerol metabolism has been well studied biochemically. However, the means by which glycerol functions in plant development is not well understood. This study aimed to investigate the mechanism underlying the effects of glycerol on root development in Arabidopsis thaliana. Exogenous glycerol inhibited primary root growth and altered lateral root development in wild-type plants. These phenotypes appeared concurrently with increased endogenous glycerol-3-phosphate (G3P) and H2O2 contents in seedlings, and decreased phosphate levels in roots. Upon glycerol treatment, G3P level and root development did not change in glycerol kinase mutant gli1, but G3P level increased in gpdhc1 and fad-gpdh mutants, which resulted in more severely impaired root development. Overexpression of the FAD-GPDH gene attenuated the alterations in G3P, phosphate and H2O2 levels, leading to increased tolerance to exogenous glycerol, which suggested that FAD-GPDH plays an important role in modulating this response. Free indole-3-acetic acid (IAA) content increased by 46%, and DR5pro::GUS staining increased in the stele cells of the root meristem under glycerol treatment, suggesting that glycerol likely alters normal auxin distribution. Decreases in PIN1 and PIN7 expression, β-glucuronidase (GUS) staining in plants expressing PIN7pro::GUS and green fluorescent protein (GFP) fluorescence in plants expressing PIN7pro::PIN7-GFP were observed, indicating that polar auxin transport in the root was downregulated under glycerol treatment. Analyses with auxin-related mutants showed that TIR1 and ARF7 were involved in regulating root growth under glycerol treatment. Glycerol-treated plants showed significant reductions in root meristem size and cell number as revealed by CYCB1;1pro::GUS staining. Furthermore, the expression of CDKA and CYCB1 decreased significantly in treated plants compared with control plants, implying possible alterations in cell cycle progression. Our data demonstrated that glycerol

  2. Mutations in exocyst complex subunit SEC6 gene impaired polar auxin transport and PIN protein recycling in Arabidopsis primary root.

    Science.gov (United States)

    Tan, Xiaoyun; Feng, Yihong; Liu, Yulong; Bao, Yiqun

    2016-09-01

    Polar auxin transport, which is critical for land plant pattern formation and directional growth, is largely depended on asymmetric distribution of PIN proteins at the plasma membrane (PM). Endocytosis and recycling processes play important roles in regulating PIN protein distribution and abundance at the PM. Two subunits (SEC8, EXO70A1) of exocyst, an octameric vesicle-tethering complex, have been reported to be involved in PIN protein recycling in Arabidopsis. However, the function of exocyst complex in PIN protein recycling and polar auxin transport remains incompletely understood. In this study, we utilized two SEC6 down-regulation mutants (PRsec6-1 and PRsec6-2) to investigate the role of exocyst subunit SEC6 in the primary root development, polar auxin transport and PIN proteins recycling. We found that in PRsec6 mutants: 1. Primary root growth was retarded, and lateral root initiation were compromised. 2. Primary roots were sensitive to exogenous auxin 1-napthalene acetic acid (NAA) but not 2,4-dichlorophenoxy (2.4-D). 3. Recycling of PIN1 and PIN2 proteins from the Brefeldin A (BFA) compartment to the PM was delayed. 4. Vesicles accumulated in the primary root tip cells, especially accumulated in the cytosol closed to the PM. These results further demonstrated that the exocyst complex plays an important role in PIN protein recycling and polar auxin transport in Arabidopsis primary root. PMID:27457987

  3. Redirection of auxin flow in Arabidopsis thaliana roots after infection by root-knot nematodes.

    Science.gov (United States)

    Kyndt, Tina; Goverse, Aska; Haegeman, Annelies; Warmerdam, Sonja; Wanjau, Cecilia; Jahani, Mona; Engler, Gilbert; de Almeida Engler, Janice; Gheysen, Godelieve

    2016-08-01

    Plant-parasitic root-knot nematodes induce the formation of giant cells within the plant root, and it has been recognized that auxin accumulates in these feeding sites. Here, we studied the role of the auxin transport system governed by AUX1/LAX3 influx proteins and different PIN efflux proteins during feeding site development in Arabidopsis thaliana roots. Data generated via promoter-reporter line and protein localization analyses evoke a model in which auxin is being imported at the basipetal side of the feeding site by the concerted action of the influx proteins AUX1 and LAX3, and the efflux protein PIN3. Mutants in auxin influx proteins AUX1 and LAX3 bear significantly fewer and smaller galls, revealing that auxin import into the feeding sites is needed for their development and expansion. The feeding site development in auxin export (PIN) mutants was only slightly hampered. Expression of some PINs appears to be suppressed in galls, probably to prevent auxin drainage. Nevertheless, a functional PIN4 gene seems to be a prerequisite for proper nematode development and gall expansion, most likely by removing excessive auxin to stabilize the hormone level in the feeding site. Our data also indicate a role of local auxin peaks in nematode attraction towards the root. PMID:27312670

  4. Potassium Transporter KUP7 Is Involved in K(+) Acquisition and Translocation in Arabidopsis Root under K(+)-Limited Conditions.

    Science.gov (United States)

    Han, Min; Wu, Wei; Wu, Wei-Hua; Wang, Yi

    2016-03-01

    Potassium (K(+)) is one of the essential macronutrients for plant growth and development. K(+) uptake from environment and K(+) translocation in plants are conducted by K(+) channels and transporters. In this study, we demonstrated that KT/HAK/KUP transporter KUP7 plays crucial roles in K(+) uptake and translocation in Arabidopsis root. The kup7 mutant exhibited a sensitive phenotype on low-K(+) medium, whose leaves showed chlorosis symptoms compared with wild-type plants. Loss of function of KUP7 led to a reduction of K(+) uptake rate and K(+) content in xylem sap under K(+)-deficient conditions. Thus, the K(+) content in kup7 shoot was significantly reduced under low-K(+) conditions. Localization analysis revealed that KUP7 was predominantly targeted to the plasma membrane. The complementation assay in yeast suggested that KUP7 could mediate K(+) transport. In addition, phosphorylation on S80, S719, and S721 was important for KUP7 activity. KUP7 was ubiquitously expressed in many organs/tissues, and showed a higher expression level in Arabidopsis root. Together, our data demonstrated that KUP7 is crucial for K(+) uptake in Arabidopsis root and might be also involved in K(+) transport into xylem sap, affecting K(+) translocation from root toward shoot, especially under K(+)-limited conditions. PMID:26851373

  5. Phosphate availability alters architecture and causes changes in hormone sensitivity in the Arabidopsis root system.

    Science.gov (United States)

    López-Bucio, José; Hernández-Abreu, Esmeralda; Sánchez-Calderón, Lenin; Nieto-Jacobo, María Fernanda; Simpson, June; Herrera-Estrella, Luis

    2002-05-01

    The postembryonic developmental program of the plant root system is plastic and allows changes in root architecture to adapt to environmental conditions such as water and nutrient availability. Among essential nutrients, phosphorus (P) often limits plant productivity because of its low mobility in soil. Therefore, the architecture of the root system may determine the capacity of the plant to acquire this nutrient. We studied the effect of P availability on the development of the root system in Arabidopsis. We found that at P-limiting conditions (increase in auxin sensitivity in the roots of P-deprived Arabidopsis seedlings. It was also found that the axr1-3, axr2-1, and axr4-1 Arabidopsis mutants have normal responses to low P availability conditions, whereas the iaa28-1 mutant shows resistance to the stimulatory effects of low P on root hair and lateral root formation. Analysis of ethylene signaling mutants and treatments with 1-aminocyclopropane-1-carboxylic acid showed that ethylene does not promote lateral root formation under P deprivation. These results suggest that in Arabidopsis, auxin sensitivity may play a fundamental role in the modifications of root architecture by P availability. PMID:12011355

  6. A theoretical model for ROP localisation by auxin in Arabidopsis root hair cells.

    Directory of Open Access Journals (Sweden)

    Robert J H Payne

    Full Text Available Local activation of Rho GTPases is important for many functions including cell polarity, morphology, movement, and growth. Although a number of molecules affecting Rho-of-Plants small GTPase (ROP signalling are known, it remains unclear how ROP activity becomes spatially organised. Arabidopsis root hair cells produce patches of ROP at consistent and predictable subcellular locations, where root hair growth subsequently occurs.We present a mathematical model to show how interaction of the plant hormone auxin with ROPs could spontaneously lead to localised patches of active ROP via a Turing or Turing-like mechanism. Our results suggest that correct positioning of the ROP patch depends on the cell length, low diffusion of active ROP, a gradient in auxin concentration, and ROP levels. Our theory provides a unique explanation linking the molecular biology to the root hair phenotypes of multiple mutants and transgenic lines, including OX-ROP, CA-rop, aux1, axr3, tip1, eto1, etr1, and the triple mutant aux1 ein2 gnom(eb.We show how interactions between Rho GTPases (in this case ROPs and regulatory molecules (in this case auxin could produce characteristic subcellular patterning that subsequently affects cell shape. This has important implications for research on the morphogenesis of plants and other eukaryotes. Our results also illustrate how gradient-regulated Turing systems provide a particularly robust and flexible mechanism for pattern formation.

  7. SAGE ANALYSIS OF TRANSCRIPTOME RESPONSES IN ARABIDOPSIS ROOTS EXPOSED TO 2,4,6-TRINITROTOLUENE

    Science.gov (United States)

    Serial Analysis of Gene Expression (SAGE) was used to profile transcript levels in Arabidopsis thaliana roots and assess their responses to 2,4,6-trinitrotoluene (TNT) exposure. SAGE libraries representing control and TNT-exposed seedling root transcripts were constructed, and ea...

  8. Geometric analysis of Arabidopsis root apex reveals a new aspect of the ethylene signal transduction pathway in development

    Science.gov (United States)

    Cervantes, Emilio; Tocino, Angel

    2005-01-01

    Structurally, ethylene is the simplest phytohormone and regulates multiple aspects of plant growth and development. Its effects are mediated by a signal transduction cascade involving receptors, MAP kinases and transcription factors. Many morphological effects of ethylene in plant development, including root size, have been previously described. In this article a combined geometric and algebraic approach has been used to analyse the shape and the curvature in the root apex of Arabidopsis seedlings. The process requires the fitting of Bezier curves that reproduce the root apex shape, and the calculation of the corresponding curvatures. The application of the method has allowed us to identify significant differences in the root curvatures of ethylene insensitive mutants (ein2-1 and etr1-1) with respect to the wild-type Columbia.

  9. Arabidopsis ERF1 Mediates Cross-Talk between Ethylene and Auxin Biosynthesis during Primary Root Elongation by Regulating ASA1 Expression.

    Directory of Open Access Journals (Sweden)

    Jie-Li Mao

    2016-01-01

    Full Text Available The gaseous phytohormone ethylene participates in the regulation of root growth and development in Arabidopsis. It is known that root growth inhibition by ethylene involves auxin, which is partially mediated by the action of the WEAK ETHYLENE INSENSITIVE2/ANTHRANILATE SYNTHASE α1 (WEI2/ASA1, encoding a rate-limiting enzyme in tryptophan (Trp biosynthesis, from which auxin is derived. However, the molecular mechanism by which ethylene decreases root growth via ASA1 is not understood. Here we report that the ethylene-responsive AP2 transcription factor, ETHYLENE RESPONSE FACTOR1 (ERF1, plays an important role in primary root elongation of Arabidopsis. Using loss- and gain-of-function transgenic lines as well as biochemical analysis, we demonstrate that ERF1 can directly up-regulate ASA1 by binding to its promoter, leading to auxin accumulation and ethylene-induced inhibition of root growth. This discloses one mechanism linking ethylene signaling and auxin biosynthesis in Arabidopsis roots.

  10. Arabidopsis ERF1 Mediates Cross-Talk between Ethylene and Auxin Biosynthesis during Primary Root Elongation by Regulating ASA1 Expression

    Science.gov (United States)

    Wang, Zhen; Yu, Lin-Hui; Cai, Xiao-Teng; Xiang, Cheng-Bin

    2016-01-01

    The gaseous phytohormone ethylene participates in the regulation of root growth and development in Arabidopsis. It is known that root growth inhibition by ethylene involves auxin, which is partially mediated by the action of the WEAK ETHYLENE INSENSITIVE2/ANTHRANILATE SYNTHASE α1 (WEI2/ASA1), encoding a rate-limiting enzyme in tryptophan (Trp) biosynthesis, from which auxin is derived. However, the molecular mechanism by which ethylene decreases root growth via ASA1 is not understood. Here we report that the ethylene-responsive AP2 transcription factor, ETHYLENE RESPONSE FACTOR1 (ERF1), plays an important role in primary root elongation of Arabidopsis. Using loss- and gain-of-function transgenic lines as well as biochemical analysis, we demonstrate that ERF1 can directly up-regulate ASA1 by binding to its promoter, leading to auxin accumulation and ethylene-induced inhibition of root growth. This discloses one mechanism linking ethylene signaling and auxin biosynthesis in Arabidopsis roots. PMID:26745809

  11. Different Degree in Proteasome Malfunction Has Various Effects on Root Growth Possibly through Preventing Cell Division and Promoting Autophagic Vacuolization

    OpenAIRE

    Xianyong Sheng; Qian Wei; Liping Jiang; Xue Li; Yuan Gao; Li Wang

    2012-01-01

    The ubiquitin/proteasome pathway plays a vital role in plant development. But the effects of proteasome malfunction on root growth, and the mechanism underlying this involvement remains unclear. In the present study, the effects of proteasome inhibitors on Arabidopsis root growth were studied through the analysis of the root length, and meristem size and cell length in maturation zone using FM4-64, and cell-division potential using GFP fusion cyclin B, and accumulation of ubiquitinated protei...

  12. Genetic ablation of root cap cells in Arabidopsis

    OpenAIRE

    Tsugeki, Ryuji; Fedoroff, Nina V.

    1999-01-01

    The root cap is increasingly appreciated as a complex and dynamic plant organ. Root caps sense and transmit environmental signals, synthesize and secrete small molecules and macromolecules, and in some species shed metabolically active cells. However, it is not known whether root caps are essential for normal shoot and root development. We report the identification of a root cap-specific promoter and describe its use to genetically ablate root caps by directing root cap-specific expression of...

  13. Use of Rhizosphere Metabolomics to Investigate Exudation of Phenolics by Arabidopsis Roots

    Science.gov (United States)

    Lee, Yong Jian; Rai, Amit; Reuben, Sheela; Nesati, Victor; Almeida, Reinaldo; Swarup, Sanjay

    2013-04-01

    The rhizosphere is a specialised micro-niche for bacteria that have an active exchange of signals and nutrients with the host plant. Nearly 20% of photosynthates are released as root exudates, which consist of primary metabolites and products of secondary metabolism which are largely phenolic in nature. Previously, using rhizosphere metabolomics, we showed that nearly 50% of organic carbon in the exudates is in the form of phenolic compounds, of which the largest fraction is from the phenylpropanoid synthesis pathway. Using Arabidopsis as a model, we have demonstrated that a biased rhizosphere can be created using plants with varying levels of phenylpropanoids due to mutations in the biosynthetic or regulatory genes. These phenylpropanoids levels are reflected in the exudates, and exudates from lines with regulatory gene mutations, tt8 and ttg, have higher levels of phenylpropanoids, whereas biosynthetic mutant line, tt4, has very low and undetectable levels of phenylpropanoids. The biased rhizosphere of tt8 and ttg lines provides a nutritional advantage to rhizobacteria that can utilize these phenylpropanoids such as quercetin. With such a strategy to increase the competitiveness of plant growth-promoting rhizobacteria (PGPR) such as Pseudomonas putida, this system can be applied to improve plant performance. In order to better understand the metabolic basis of the nutritional advantage behind the competitiveness of the favoured P. putida, we elucidated its quercetin utilization pathway. We have recently cloned the gene for quercetin oxidoreductase (QuoA) and expressed it in transgenic Arabidopsis lines to alter the plant phenylpropanoid metabolism, using a gain of function approach. Since phenylpropanoid biosynthesis in plants involve formation of quercetin from naringenin, we envisaged that QuoA expression in plants will provide us with a genetic tool to "reverse" this biosynthetic step. This perturbation led to a decrease in flavonoids and an increase in lignin

  14. L-Cysteine inhibits root elongation through auxin/PLETHORA and SCR/SHR pathway in Arabidopsis thaliana

    Institute of Scientific and Technical Information of China (English)

    Zhen Wang; Jie-Li Mao; Ying-Jun Zhao; Chuan-You Li; Cheng-Bin Xiang

    2015-01-01

    L‐Cysteine plays a prominent role in sulfur metabo-lism of plants. However, its role in root development is largely unknown. Here, we report that L‐cysteine reduces primary root growth in a dosage‐dependent manner. Elevating cel ular L‐cysteine level by exposing Arabidopsis thaliana seedlings to high L‐cysteine, buthionine sulphoximine, or O‐acetylserine leads to altered auxin maximum in root tips, the expression of quiescent center cel marker as wel as the decrease of the auxin carriers PIN1, PIN2, PIN3, and PIN7 of primary roots. We also show that high L‐cysteine significantly reduces the protein level of two sets of stem cel specific transcription factors PLETHORA1/2 and SCR/SHR. However, L‐cysteine does not downregulate the transcript level of PINs, PLTs, or SCR/SHR, suggesting that an uncharacterized post‐transcriptional mech-anism may regulate the accumulation of PIN, PLT, and SCR/SHR proteins and auxin transport in the root tips. These results suggest that endogenous L‐cysteine level acts to maintain root stem cel niche by regulating basal‐and auxin‐induced expression of PLT1/2 and SCR/SHR. L‐Cysteine may serve as a link between sulfate assimilation and auxin in regulating root growth.

  15. The role of Arabidopsis 5PTase13 in root gravitropism through modulation of vesicle trafficking

    Institute of Scientific and Technical Information of China (English)

    Yuan Wang; Wen-Hui Lin; Xu Chen; Hong-Wei Xue

    2009-01-01

    Inositol polyphosphate 5-phosphatases (5PTases) are enzymes of phosphatidylinositoi metabolism that affect various aspects of plant growth and development. Arabidopsis 5PTasel3 regulates auxin homeostasis and hormone-related cotyledon vein development, and here we demonstrate that its knockout mutant 5pt13 has elevated sensitivity to gravistimulation in root gravitropic responses. The altered responses of 5pt13 mutants to 1-N-naphthylphthalamic acid (an auxin transport inhibitor) indicate that 5PTasel3 might be involved in the regulation of auxin transport. Indeed, the auxin efflux carrier PIN2 is expressed more broadly under 5PTasel3 deficiency, and observations of the internalization of the membrane-selective dye FM4-64 reveal altered vesicle trafficking in 5pt13 mutants. Compared with wild-type, 5pt13 mutant seedlings are less sensitive to the inhibition by brefeldin A of vesicle cycling, seedling growth, and the intracellular cycling of the PINI and PIN2 proteins. Further, auxin redistribution upon gravitropic stimulation is stimulated under 5PTasel3 deficiency. These results suggest that 5PTasel3 may modulate auxin trans-port by regulating vesicle trafficking and thereby play a role in root gravitropism.

  16. Genetic Analysis of Gravity Signal Transduction in Arabidopsis Roots

    Science.gov (United States)

    Masson, Patrick; Strohm, Allison; Barker, Richard; Su, Shih-Heng

    Like most other plant organs, roots use gravity as a directional guide for growth. Specialized cells within the columella region of the root cap (the statocytes) sense the direction of gravity through the sedimentation of starch-filled plastids (amyloplasts). Amyloplast movement and/or pressure on sensitive membranes triggers a gravity signal transduction pathway within these cells, which leads to a fast transcytotic relocalization of plasma-membrane associated auxin-efflux carrier proteins of the PIN family (PIN3 and PIN7) toward the bottom membrane. This leads to a polar transport of auxin toward the bottom flank of the cap. The resulting lateral auxin gradient is then transmitted toward the elongation zones where it triggers a curvature that ultimately leads to a restoration of vertical downward growth. Our laboratory is using strategies derived from genetics and systems biology to elucidate the molecular mechanisms that modulate gravity sensing and signal transduction in the columella cells of the root cap. Our previous research uncovered two J-domain-containing proteins, ARG1 and ARL2, as contributing to this process. Mutations in the corresponding paralogous genes led to alterations of root and hypocotyl gravitropism accompanied by an inability for the statocytes to develop a cytoplasmic alkalinization, relocalize PIN3, and transport auxin laterally, in response to gravistimulation. Both proteins are associated peripherally to membranes belonging to various compartments of the vesicular trafficking pathway, potentially modulating the trafficking of defined proteins between plasma membrane and endosomes. MAR1 and MAR2, on the other end, are distinct proteins of the plastidic outer envelope protein import TOC complex (the transmembrane channel TOC75 and the receptor TOC132, respectively). Mutations in the corresponding genes enhance the gravitropic defects of arg1. Using transformation-rescue experiments with truncated versions of TOC132 (MAR2), we have shown

  17. Chromate alters root system architecture and activates expression of genes involved in iron homeostasis and signaling in Arabidopsis thaliana.

    Science.gov (United States)

    Martínez-Trujillo, Miguel; Méndez-Bravo, Alfonso; Ortiz-Castro, Randy; Hernández-Madrigal, Fátima; Ibarra-Laclette, Enrique; Ruiz-Herrera, León Francisco; Long, Terri A; Cervantes, Carlos; Herrera-Estrella, Luis; López-Bucio, José

    2014-09-01

    Soil contamination by hexavalent chromium [Cr(VI) or chromate] due to anthropogenic activities has become an increasingly important environmental problem. To date few studies have been performed to elucidate the signaling networks involved on adaptive responses to (CrVI) toxicity in plants. In this work, we report that depending upon its concentration, Cr(VI) alters in different ways the architecture of the root system in Arabidopsis thaliana seedlings. Low concentrations of Cr (20-40 µM) promoted primary root growth, while concentrations higher than 60 µM Cr repressed growth and increased formation of root hairs, lateral root primordia and adventitious roots. We analyzed global gene expression changes in seedlings grown in media supplied with 20 or 140 µM Cr. The level of 731 transcripts was significantly modified in response to Cr treatment with only five genes common to both Cr concentrations. Interestingly, 23 genes related to iron (Fe) acquisition were up-regulated including IRT1, YSL2, FRO5, BHLH100, BHLH101 and BHLH039 and the master controllers of Fe deficiency responses PYE and BTS were specifically activated in pericycle cells. It was also found that increasing concentration of Cr in the plant correlated with a decrease in Fe content, but increased both acidification of the rhizosphere and activity of the ferric chelate reductase. Supply of Fe to Cr-treated Arabidopsis allowed primary root to resume growth and alleviated toxicity symptoms, indicating that Fe nutrition is a major target of Cr stress in plants. Our results show that low Cr levels are beneficial to plants and that toxic Cr concentrations activate a low-Fe rescue system. PMID:24928490

  18. Functional Analysis of the Arabidopsis TETRASPANIN Gene Family in Plant Growth and Development.

    Science.gov (United States)

    Wang, Feng; Muto, Antonella; Van de Velde, Jan; Neyt, Pia; Himanen, Kristiina; Vandepoele, Klaas; Van Lijsebettens, Mieke

    2015-11-01

    TETRASPANIN (TET) genes encode conserved integral membrane proteins that are known in animals to function in cellular communication during gamete fusion, immunity reaction, and pathogen recognition. In plants, functional information is limited to one of the 17 members of the Arabidopsis (Arabidopsis thaliana) TET gene family and to expression data in reproductive stages. Here, the promoter activity of all 17 Arabidopsis TET genes was investigated by pAtTET::NUCLEAR LOCALIZATION SIGNAL-GREEN FLUORESCENT PROTEIN/β-GLUCURONIDASE reporter lines throughout the life cycle, which predicted functional divergence in the paralogous genes per clade. However, partial overlap was observed for many TET genes across the clades, correlating with few phenotypes in single mutants and, therefore, requiring double mutant combinations for functional investigation. Mutational analysis showed a role for TET13 in primary root growth and lateral root development and redundant roles for TET5 and TET6 in leaf and root growth through negative regulation of cell proliferation. Strikingly, a number of TET genes were expressed in embryonic and seedling progenitor cells and remained expressed until the differentiation state in the mature plant, suggesting a dynamic function over developmental stages. The cis-regulatory elements together with transcription factor-binding data provided molecular insight into the sites, conditions, and perturbations that affect TET gene expression and positioned the TET genes in different molecular pathways; the data represent a hypothesis-generating resource for further functional analyses. PMID:26417009

  19. Salt stress response triggers activation of the jasmonate signaling pathway leading to inhibition of cell elongation in Arabidopsis primary root.

    Science.gov (United States)

    Valenzuela, Camilo E; Acevedo-Acevedo, Orlando; Miranda, Giovanna S; Vergara-Barros, Pablo; Holuigue, Loreto; Figueroa, Carlos R; Figueroa, Pablo M

    2016-07-01

    Salinity is a severe abiotic stress that affects irrigated croplands. Jasmonate (JA) is an essential hormone involved in plant defense against herbivory and in responses to abiotic stress. However, the relationship between the salt stress response and the JA pathway in Arabidopsis thaliana is not well understood at molecular and cellular levels. In this work we investigated the activation of JA signaling by NaCl and its effect on primary root growth. We found that JA-responsive JAZ genes were up-regulated by salt stress in a COI1-dependent manner in the roots. Using a JA-Ile sensor we demonstrated that activation of JA signaling by salt stress occurs in the meristematic zone and stele of the differentiation zone and that this activation was dependent on JAR1 and proteasome functions. Another finding is that the elongation zone (EZ) and its cortical cells were significantly longer in JA-related mutants (AOS, COI1, JAZ3 and MYC2/3/4 genes) compared with wild-type plants under salt stress, revealing the participation of the canonical JA signaling pathway. Noteworthy, osmotic stress - a component of salt stress - inhibited cell elongation in the EZ in a COI1-dependent manner. We propose that salt stress triggers activation of the JA signaling pathway followed by inhibition of cell elongation in the EZ. We have shown that salt-inhibited root growth partially involves the jasmonate signaling pathway in Arabidopsis. PMID:27217545

  20. Auxin and Cytokinin Metabolism and Root Morphological Modifications in Arabidopsis thaliana Seedlings Infected with Cucumber mosaic virus (CMV or Exposed to Cadmium

    Directory of Open Access Journals (Sweden)

    Adriano Sofo

    2013-03-01

    Full Text Available Arabidopsis thaliana L. is a model plant but little information is available about morphological root changes as part of a phytohormonal common response against both biotic and abiotic stressors. For this purpose, two-week-old Arabidopsis seedlings were treated with 10 µM CdSO4 or infected with CMV. After 12 days the entire aerial parts and the root system were analyzed, and the presence of CMV or the accumulation of Cd were detected. Microscopic analysis revealed that both CMV and Cd influenced root morphology by a marked development in the length of root hairs and an intense root branching if compared to controls. Among the three treatments, Cd-treated seedlings showed a shorter root axis length and doubled their lateral root diameter, while the lateral roots of CMV-infected seedlings were the longest. The root growth patterns were accompanied by significant changes in the levels of indole-3-acetic acid, trans-zeatin riboside, dihydrozeatin riboside, as a probable consequence of the regulation of some genes involved in their biosynthesis/degradation. The opposite role on root development played by the phythormones studied is discussed in detail. The results obtained could provide insights into novel strategies for plant defense against pathogens and plant protection against pollutants.

  1. Corn-on-a-chip: Mini-channel Device for Corn Root Growth

    Science.gov (United States)

    Kreis, Kevin; Ryu, Sangjin

    2015-11-01

    Plant growth heavily relies on interactions between the root and the soil environment, but it is impossible to observe such interactions because of opaqueness of soil. Microfluidics has been successfully utilized to monitor the root growth behaviors of Arabidopsis. In this study we have chosen Maize as a model plant because of its economic significance, and aim to develop transparent mini-channel devices accommodating the root growth of corn seedlings in a controlled environment. To mimic aspects of the soil environment, we try to impose concentration gradients of key chemical ions to the growing root using the device, and to investigate how the root responds to the applied stimuli. We acknowledge support from NASA Nebraska Space Grant Fellowship.

  2. Auxin gradient is crucial for the maintenance of root distal stem cell identity in Arabidopsis

    OpenAIRE

    Tian, Huiyu; Niu, Tiantian; Yu, Qianqian; Quan, Taiyong; Ding, Zhaojun

    2013-01-01

    The plant hormone auxin plays a critical role in the maintenance of root stem cell niches in Arabidopsis. We have recently reported that WUSCHEL-RELATED HOMEOBOX 5 (WOX5) transcription factor modulates free auxin production in the quiescent center (QC) of the root and its expression is inhibited in a feedback-dependent manner by canonical auxin signaling that involves indole-3-acetic acid 17 (IAA17) auxin response repressor. WOX5-IAA17 feedback circuit assures the maintenance of auxin respons...

  3. Chromium-Induced Ultrastructural Changes and Oxidative Stress in Roots of Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Eleftherios P. Eleftheriou

    2015-07-01

    Full Text Available Chromium (Cr is an abundant heavy metal in nature, toxic to living organisms. As it is widely used in industry and leather tanning, it may accumulate locally at high concentrations, raising concerns for human health hazards. Though Cr effects have extensively been investigated in animals and mammals, in plants they are poorly understood. The present study was then undertaken to determine the ultrastructural malformations induced by hexavalent chromium [Cr(VI], the most toxic form provided as 100 μM potassium dichromate (K2Cr2O7, in the root tip cells of the model plant Arabidopsis thaliana. A concentration-dependent decrease of root growth and a time-dependent increase of dead cells, callose deposition, hydrogen peroxide (H2O2 production and peroxidase activity were found in Cr(VI-treated seedlings, mostly at the transition root zone. In the same zone, nuclei remained ultrastructurally unaffected, but in the meristematic zone some nuclei displayed bulbous outgrowths or contained tubular structures. Endoplasmic reticulum (ER was less affected under Cr(VI stress, but Golgi bodies appeared severely disintegrated. Moreover, mitochondria and plastids became spherical and displayed translucent stroma with diminished internal membranes, but noteworthy is that their double-membrane envelopes remained structurally intact. Starch grains and electron dense deposits occurred in the plastids. Amorphous material was also deposited in the cell walls, the middle lamella and the vacuoles. Some vacuoles were collapsed, but the tonoplast appeared integral. The plasma membrane was structurally unaffected and the cytoplasm contained opaque lipid droplets and dense electron deposits. All electron dense deposits presumably consisted of Cr that is sequestered from sensitive sites, thus contributing to metal tolerance. It is concluded that the ultrastructural changes are reactive oxygen species (ROS-correlated and the malformations observed are organelle specific.

  4. Chromium-Induced Ultrastructural Changes and Oxidative Stress in Roots of Arabidopsis thaliana.

    Science.gov (United States)

    Eleftheriou, Eleftherios P; Adamakis, Ioannis-Dimosthenis S; Panteris, Emmanuel; Fatsiou, Maria

    2015-01-01

    Chromium (Cr) is an abundant heavy metal in nature, toxic to living organisms. As it is widely used in industry and leather tanning, it may accumulate locally at high concentrations, raising concerns for human health hazards. Though Cr effects have extensively been investigated in animals and mammals, in plants they are poorly understood. The present study was then undertaken to determine the ultrastructural malformations induced by hexavalent chromium [Cr(VI)], the most toxic form provided as 100 μM potassium dichromate (K2Cr2O7), in the root tip cells of the model plant Arabidopsis thaliana. A concentration-dependent decrease of root growth and a time-dependent increase of dead cells, callose deposition, hydrogen peroxide (H2O2) production and peroxidase activity were found in Cr(VI)-treated seedlings, mostly at the transition root zone. In the same zone, nuclei remained ultrastructurally unaffected, but in the meristematic zone some nuclei displayed bulbous outgrowths or contained tubular structures. Endoplasmic reticulum (ER) was less affected under Cr(VI) stress, but Golgi bodies appeared severely disintegrated. Moreover, mitochondria and plastids became spherical and displayed translucent stroma with diminished internal membranes, but noteworthy is that their double-membrane envelopes remained structurally intact. Starch grains and electron dense deposits occurred in the plastids. Amorphous material was also deposited in the cell walls, the middle lamella and the vacuoles. Some vacuoles were collapsed, but the tonoplast appeared integral. The plasma membrane was structurally unaffected and the cytoplasm contained opaque lipid droplets and dense electron deposits. All electron dense deposits presumably consisted of Cr that is sequestered from sensitive sites, thus contributing to metal tolerance. It is concluded that the ultrastructural changes are reactive oxygen species (ROS)-correlated and the malformations observed are organelle specific. PMID:26204828

  5. Root system architecture: insights from Arabidopsis and cereal crops

    OpenAIRE

    Smith, Stephanie; De Smet, Ive

    2012-01-01

    Roots are important to plants for a wide variety of processes, including nutrient and water uptake, anchoring and mechanical support, storage functions, and as the major interface between the plant and various biotic and abiotic factors in the soil environment. Understanding the development and architecture of roots holds potential for the exploitation and manipulation of root characteristics to both increase food plant yield and optimize agricultural land use. This theme issue highlights the...

  6. The OXI1 kinase pathway mediates Piriformospora indica-induced growth promotion in Arabidopsis.

    Directory of Open Access Journals (Sweden)

    Iris Camehl

    2011-05-01

    Full Text Available Piriformospora indica is an endophytic fungus that colonizes roots of many plant species and promotes growth and resistance to certain plant pathogens. Despite its potential use in agriculture, little is known on the molecular basis of this beneficial plant-fungal interaction. In a genetic screen for plants, which do not show a P. indica- induced growth response, we isolated an Arabidopsis mutant in the OXI1 (Oxidative Signal Inducible1 gene. OXI1 has been characterized as a protein kinase which plays a role in pathogen response and is regulated by H₂O₂ and PDK1 (3-PHOSPHOINOSITIDE-DEPENDENT PROTEIN KINASE1. A genetic analysis showed that double mutants of the two closely related PDK1.1 and PDK1.2 genes are defective in the growth response to P. indica. While OXI1 and PDK1 gene expression is upregulated in P. indica-colonized roots, defense genes are downregulated, indicating that the fungus suppresses plant defense reactions. PDK1 is activated by phosphatidic acid (PA and P. indica triggers PA synthesis in Arabidopsis plants. Under beneficial co-cultivation conditions, H₂O₂ formation is even reduced by the fungus. Importantly, phospholipase D (PLDα1 or PLDδ mutants, which are impaired in PA synthesis do not show growth promotion in response to fungal infection. These data establish that the P. indica-stimulated growth response is mediated by a pathway consisting of the PLD-PDK1-OXI1 cascade.

  7. Cytokinin-dependent secondary growth determines root biomass in radish (Raphanus sativus L.).

    Science.gov (United States)

    Jang, Geupil; Lee, Jung-Hun; Rastogi, Khushboo; Park, Suhyoung; Oh, Sang-Hun; Lee, Ji-Young

    2015-08-01

    The root serves as an essential organ in plant growth by taking up nutrients and water from the soil and supporting the rest of the plant body. Some plant species utilize roots as storage organs. Sweet potatoes (Ipomoea batatas), cassava (Manihot esculenta), and radish (Raphanus sativus), for example, are important root crops. However, how their root growth is regulated remains unknown. In this study, we characterized the relationship between cambium and radial root growth in radish. Through a comparative analysis with Arabidopsis root expression data, we identified putative cambium-enriched transcription factors in radish and analysed their expression in representative inbred lines featuring distinctive radial growth. We found that cell proliferation activities in the cambium positively correlated with radial growth and final yields of radish roots. Expression analysis of candidate transcription factor genes revealed that some genes are differentially expressed between inbred lines and that the difference is due to the distinct cytokinin response. Taken together, we have demonstrated for the first time, to the best of our knowledge, that cytokinin-dependent radial growth plays a key role in the yields of root crops. PMID:25979997

  8. NADH-dependent glutamate synthase participated in ammonium assimilation in Arabidopsis root

    OpenAIRE

    Kojima, Soichi; KONISHI Noriyuki; Beier, Marcel Pascal; Ishiyama, Keiki; Maru, Ikumi; Hayakawa, Toshihiko; Yamaya, Tomoyuki

    2014-01-01

    Higher plants have 2 GOGAT species, Fd-GOGAT and NADH-GOGAT. While Fd-GOGAT mainly assimilates ammonium in leaves, which is derived from photorespiration, the function of NADH-GOGAT, which is highly expressed in roots,1 needs to be elucidated. The aim of this study was to clarify the role of NADH-GOGAT in Arabidopsis roots. The supply of ammonium to the roots caused an accumulation of NADH-GOGAT, while Fd-GOGAT 1 and Fd-GOGAT 2 showed no response. A promoter–GUS fusion analysis and immunohist...

  9. The acquisition of cell fate in the Arabidopsis thaliana root meristem

    NARCIS (Netherlands)

    Scheres, B.J.G.; Berg, C. van den; Hage, W.; Willemsen, V.; Werff, N. van der; Wolkenfelt, H.; McKhann, H.; Weisbeek, P.

    1997-01-01

    During plant embryogenesis an embryo with cotyledons, a shoot apical meristem, a hypocotyl and a root apical meristem, is formed. The primary root and shoot meristems initiate post-embryonic growth generating all plant organs. The root meristem forms the primary root, and the shoot meristem forms th

  10. Oscillating Gene Expression Determines Competence for Periodic Arabidopsis Root Branching

    Science.gov (United States)

    Moreno-Risueno, Miguel A.; Van Norman, Jaimie M.; Moreno, Antonio; Zhang, Jingyuan; Ahnert, Sebastian E.; Benfey, Philip N.

    2010-01-01

    Plants and animals produce modular developmental units in a periodic fashion. In plants, lateral roots form as repeating units along the root primary axis; however, the developmental mechanism regulating this process is unknown. We found that cyclic expression pulses of a reporter gene mark the position of future lateral roots by establishing prebranch sites and that prebranch site production and root bending are periodic. Microarray and promoter-luciferase studies revealed two sets of genes oscillating in opposite phases at the root tip. Genetic studies show that some oscillating transcriptional regulators are required for periodicity in one or both developmental processes. This molecular mechanism has characteristics that resemble molecular clock–driven activities in animal species. PMID:20829477

  11. Quest for Continual Growth Takes Root

    Science.gov (United States)

    Surdey, Mary M.; Hashey, Jane M.

    2006-01-01

    In this article, the authors describe how the quest for continual growth has taken its root at Vestal Central School district. Located at the heart of upstate New York, educators at Vestal Central School district have created a spirit of "kaizen," a Japanese word meaning the relentless quest for continual improvement and higher-quality…

  12. Identification of a root-specific glycosyltransferase from Arabidopsis and characterization of its promoter

    Indian Academy of Sciences (India)

    Virupapuram Vijaybhaskar; Veeraputhiran Subbiah; Jagreet Kaur; Pagadala Vijayakumari; Imran Siddiqi

    2008-06-01

    A set of Ds-element enhancer trap lines of Arabidopsis thaliana was generated and screened for expression patterns leading to the identification of a line that showed root-specific expression of the bacterial uidA reporter gene encoding -glucuronidase (GUS). The insertion of the Ds element was found to be immediately downstream to a glycosyltransferase gene At1g73160. Analysis of At1g73160 expression showed that it is highly root-specific. Isolation and characterization of the upstream region of the At1g73160 gene led to the definition of a 218 bp fragment that is sufficient to confer root-specific expression. Sequence analysis revealed that several regulatory elements were implicated in expression in root tissue. The promoter identified and characterized in this study has the potential to be applied in crop biotechnology for directing the root-specific expression of transgenes.

  13. Glucose alleviates cadmium toxicity by increasing cadmium fixation in root cell wall and sequestration into vacuole in Arabidopsis

    Institute of Scientific and Technical Information of China (English)

    Yuan-Zhi Shi; Xiao-Fang Zhu; Jiang-Xue Wan; Gui-Xin Li; Shao-Jian Zheng

    2015-01-01

    Glucose (Glu) is involved in not only plant physiological and developmental events but also plant responses to abiotic stresses. Here, we found that the exogenous Glu improved root and shoot growth, reduced shoot cadmium (Cd) concentration, and rescued Cd-induced chlorosis in Arabidopsis thaliana (Columbia ecotype, Col-0) under Cd stressed conditions. Glucose increased Cd retained in the roots, thus reducing its translocation from root to shoot significantly. The most Cd retained in the roots was found in the hemicellulose 1. Glucose combined with Cd (Glu þ Cd) treatment did not affect the content of pectin and its binding capacity of Cd while it increased the content of hemicelluloses 1 and the amount of Cd retained in it significantly. Furthermore, Leadmium Green staining indicated that more Cd was compartmented into vacuoles in Glu þ Cd treatment compared with Cd treatment alone, which was in accordance with the significant upregulation of the expression of tonoplast-localized metal transporter genes, suggesting that com-partmentation of Cd into vacuoles also contributes to the Glu-alleviated Cd toxicity. Taken together, we demonstrated that Glu-alleviated Cd toxicity is mediated through increas-ing Cd fixation in the root cell wall and sequestration into the vacuoles.

  14. Differential responsiveness of cortical microtubule orientation to suppression of cell expansion among the developmental zones of Arabidopsis thaliana root apex.

    Directory of Open Access Journals (Sweden)

    Emmanuel Panteris

    Full Text Available Τhe bidirectional relationship between cortical microtubule orientation and cell wall structure has been extensively studied in elongating cells. Nevertheless, the possible interplay between microtubules and cell wall elements in meristematic cells still remains elusive. Herein, the impact of cellulose synthesis inhibition and suppressed cell elongation on cortical microtubule orientation was assessed throughout the developmental zones of Arabidopsis thaliana root apex by whole-mount tubulin immunolabeling and confocal microscopy. Apart from the wild-type, thanatos and pom2-4 mutants of Cellulose SynthaseA3 and Cellulose Synthase Interacting1, respectively, were studied. Pharmacological and mechanical approaches inhibiting cell expansion were also applied. Cortical microtubules of untreated wild-type roots were predominantly transverse in the meristematic, transition and elongation root zones. Cellulose-deficient mutants, chemical inhibition of cell expansion, or growth in soil resulted in microtubule reorientation in the elongation zone, wherein cell length was significantly decreased. Combinatorial genetic and chemical suppression of cell expansion extended microtubule reorientation to the transition zone. According to the results, transverse cortical microtubule orientation is established in the meristematic root zone, persisting upon inhibition of cell expansion. Microtubule reorientation in the elongation zone could be attributed to conditional suppression of cell elongation. The differential responsiveness of microtubule orientation to genetic and environmental cues is most likely associated with distinct biophysical traits of the cells among each developmental root zone.

  15. Differential responsiveness of cortical microtubule orientation to suppression of cell expansion among the developmental zones of Arabidopsis thaliana root apex.

    Science.gov (United States)

    Panteris, Emmanuel; Adamakis, Ioannis-Dimosthenis S; Daras, Gerasimos; Hatzopoulos, Polydefkis; Rigas, Stamatis

    2013-01-01

    Τhe bidirectional relationship between cortical microtubule orientation and cell wall structure has been extensively studied in elongating cells. Nevertheless, the possible interplay between microtubules and cell wall elements in meristematic cells still remains elusive. Herein, the impact of cellulose synthesis inhibition and suppressed cell elongation on cortical microtubule orientation was assessed throughout the developmental zones of Arabidopsis thaliana root apex by whole-mount tubulin immunolabeling and confocal microscopy. Apart from the wild-type, thanatos and pom2-4 mutants of Cellulose SynthaseA3 and Cellulose Synthase Interacting1, respectively, were studied. Pharmacological and mechanical approaches inhibiting cell expansion were also applied. Cortical microtubules of untreated wild-type roots were predominantly transverse in the meristematic, transition and elongation root zones. Cellulose-deficient mutants, chemical inhibition of cell expansion, or growth in soil resulted in microtubule reorientation in the elongation zone, wherein cell length was significantly decreased. Combinatorial genetic and chemical suppression of cell expansion extended microtubule reorientation to the transition zone. According to the results, transverse cortical microtubule orientation is established in the meristematic root zone, persisting upon inhibition of cell expansion. Microtubule reorientation in the elongation zone could be attributed to conditional suppression of cell elongation. The differential responsiveness of microtubule orientation to genetic and environmental cues is most likely associated with distinct biophysical traits of the cells among each developmental root zone. PMID:24324790

  16. Induced Systemic Resistance in Arabidopsis thaliana in Response to Root Inoculation with Pseudomonas fluorescens CHA0

    OpenAIRE

    Iavicoli, Annalisa; Boutet, Emmanuel; Buchala, Antony; Métraux, Jean-Pierre

    2006-01-01

    Root inoculation of Arabidopsis thaliana ecotype Columbia with Pseudomonas fluorescens CHA0r partially protected leaves from the oomycete Peronospora parasitica. The molecular determinants of Pseudomonas fluorescens CHA0r for this induced systemic resistance (ISR) were investigated, using mutants derived from strain CHA0: CHA400 (pyoverdine deficient), CHA805 (exoprotease deficient), CHA77 (HCN deficient), CHA660 (pyoluteorin deficient), CHA631 (2,4-diacetylphloroglucinol [DAPG] deficient), a...

  17. BES1 regulates the localization of the brassinosteroid receptor BRL3 within the provascular tissue of the Arabidopsis primary root.

    Science.gov (United States)

    Salazar-Henao, Jorge E; Lehner, Reinhard; Betegón-Putze, Isabel; Vilarrasa-Blasi, Josep; Caño-Delgado, Ana I

    2016-09-01

    Brassinosteroid (BR) hormones are important regulators of plant growth and development. Recent studies revealed the cell-specific role of BRs in vascular and stem cell development by the action of cell-specific BR receptor complexes and downstream signaling components in Arabidopsis thaliana Despite the importance of spatiotemporal regulation of hormone signaling in the control of plant vascular development, the mechanisms that confer cellular specificity to BR receptors within the vascular cells are not yet understood. The present work shows that BRI1-like receptor genes 1 and 3 (BRL1 and BRL3) are differently regulated by BRs. By using promoter deletion constructs of BRL1 and BRL3 fused to GFP/GUS (green fluorescent protein/β-glucuronidase) reporters in Arabidopsis, analysis of their cell-specific expression and regulation by BRs in the root apex has been carried out. We found that BRL3 expression is finely modulated by BRs in different root cell types, whereas the location of BRL1 appears to be independent of this hormone. Physiological and genetic analysis show a BR-dependent expression of BRL3 in the root meristem. In particular, BRL3 expression requires active BES1, a central transcriptional effector within the BRI1 pathway. ChIP analysis showed that BES1 directly binds to the BRRE present in the BRL3 promoter region, modulating its transcription in different subsets of cells of the root apex. Overall our study reveals the existence of a cell-specific negative feedback loop from BRI1-mediated BES1 transcription factor to BRL3 in phloem cells, while contributing to a general understanding of the spatial control of steroid signaling in plant development. PMID:27511026

  18. Hydrogen peroxide is involved in cGMP modulating the lateral root development of Arabidopsis thaliana

    OpenAIRE

    Li, Jisjeng; Jia, Honglei

    2013-01-01

    3′,5′-cyclic guanosine monophosphate (cGMP) and hydrogen peroxide (H2O2) function as the important signaling molecule which promote the lateral root development of Arabidopsis thaliana. In this study, interestingly, application of 8-Br-cGMP (the membrane permeable cGMP analog) promoted the endogenous H2O2 production. In addition, the decrease of endogenous H2O2 also inhibited the effect of cGMP on the lateral root development. Thus, H2O2 maybe act as a downstream signaling of cGMP molecule wh...

  19. Belowground neighbor perception in Arabidopsis thaliana studied by transcriptome analysis: roots of Hieracium pilosella cause biotic stress

    OpenAIRE

    Schmid, Christoph; Bauer, Sibylle; Müller, Benedikt; Bartelheimer, Maik

    2013-01-01

    Root-root interactions are much more sophisticated than previously thought, yet the mechanisms of belowground neighbor perception remain largely obscure. Genome-wide transcriptome analyses allow detailed insight into plant reactions to environmental cues. A root interaction trial was set up to explore both morphological and whole genome transcriptional responses in roots of Arabidopsis thaliana in the presence or absence of an inferior competitor, Hieracium pilosella. Neighbor perception was ...

  20. Endosomal Interactions during Root Hair Growth.

    Science.gov (United States)

    von Wangenheim, Daniel; Rosero, Amparo; Komis, George; Šamajová, Olga; Ovečka, Miroslav; Voigt, Boris; Šamaj, Jozef

    2015-01-01

    The dynamic localization of endosomal compartments labeled with targeted fluorescent protein tags is routinely followed by time lapse fluorescence microscopy approaches and single particle tracking algorithms. In this way trajectories of individual endosomes can be mapped and linked to physiological processes as cell growth. However, other aspects of dynamic behavior including endosomal interactions are difficult to follow in this manner. Therefore, we characterized the localization and dynamic properties of early and late endosomes throughout the entire course of root hair formation by means of spinning disc time lapse imaging and post-acquisition automated multitracking and quantitative analysis. Our results show differential motile behavior of early and late endosomes and interactions of late endosomes that may be specified to particular root hair domains. Detailed data analysis revealed a particular transient interaction between late endosomes-termed herein as dancing-endosomes-which is not concluding to vesicular fusion. Endosomes preferentially located in the root hair tip interacted as dancing-endosomes and traveled short distances during this interaction. Finally, sizes of early and late endosomes were addressed by means of super-resolution structured illumination microscopy (SIM) to corroborate measurements on the spinning disc. This is a first study providing quantitative microscopic data on dynamic spatio-temporal interactions of endosomes during root hair tip growth. PMID:26858728

  1. Distribution and regulation of auxin in Arabidopsis root cells

    OpenAIRE

    Petersson, Sara

    2011-01-01

    The plant hormone auxin (IAA) coordinates many of the important processes in plant development. For example, IAA is critical for normal embryogenesis, root development, cell elongation, and the tropic responses such as gravitropism and phototropism. IAA gradients are established and maintained in many tissues and it is thought that these gradients act as developmental cues, determining the fate of cells and tissues. Descriptions of auxin distribution patterns with cellular resolution h...

  2. Ubiquitin-specific protease 14 (UBP14) is involved in root responses to phosphate deficiency in Arabidopsis.

    Science.gov (United States)

    Li, Wen-Feng; Perry, Paula J; Prafulla, Nulu N; Schmidt, Wolfgang

    2010-01-01

    A mutant isolated from a screen of EMS-mutagenized Arabidopsis lines, per1, showed normal root hair development under control conditions but displayed an inhibited root hair elongation phenotype upon Pi deficiency. Additionally, the per1 mutant exhibited a pleiotropic phenotype under control conditions, resembling Pi-deficient plants in several aspects. Inhibition of root hair elongation upon growth on low Pi media was reverted by treatment with the Pi analog phosphite, suggesting that the mutant phenotype is not caused by a lack of Pi. Reciprocal grafting experiments revealed that the mutant rootstock is sufficient to cause the phenotype. Complementation analyses showed that the PER1 gene encodes an ubiquitin-specific protease, UBP14. The mutation caused a synonymous substitution in the 12th exon of this gene, resulting in a lower abundance of the UBP14 protein, probably as a consequence of reduced translation efficiency. Transcriptional profiling of per1 and wild-type plants subjected to short-term Pi starvation revealed genes that may be important for the signaling of Pi deficiency. We conclude that UBP14 function is crucial for adapting root development to the prevailing local availability of phosphate. PMID:19969521

  3. Bacterial volatiles promote growth in Arabidopsis

    OpenAIRE

    Ryu, Choong-Min; Mohamed A. Farag; Hu, Chia-Hui; Reddy, Munagala S.; Wei, Han-Xun; Paré, Paul W.; Kloepper, Joseph W.

    2003-01-01

    Several chemical changes in soil are associated with plant growth-promoting rhizobacteria (PGPR). Some bacterial strains directly regulate plant physiology by mimicking synthesis of plant hormones, whereas others increase mineral and nitrogen availability in the soil as a way to augment growth. Identification of bacterial chemical messengers that trigger growth promotion has been limited in part by the understanding of how plants respond to external stimuli. With an increasing appreciation of...

  4. EFFECT OF SEED XYLOGLUCANS AND DERIVATES ON THE GROWTH OF Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Adriana Tourinho Salamoni

    2009-10-01

    Full Text Available Studies on xyloglucan (XG extracted from Hymenaea courbaril L. (jatoba seeds showed that this biopolymer has biological activity that enhanced wheat coleoptiles growth. In apple tree micropropagation, the culture medium containing XG combined with agar induced a higher multiplication rate, rooting rate and root length than medium solidified with agar only. The purpose of this study was to determine the effect of XG from jatobá seeds extracted from jatoba seeds collected in Sinope/MT (XGS and Cuiabá/MT (XGC, and from XGC hydrolysed with a cellulase (XGCH, as well from Tamarindus indica seeds (XGT collected in Bahia/BA, on the growth of in vitro cultured Arabidopsis thaliana plantlets. In the first experiment, XGCH (0.25, 25 and 250 nM or XGC (0.5, 50 and 500 nM were added to a liquid half-strength MS medium. In the second experiment, XGs from several origins were compared: XGC (500 nM, XGS (1200 nM and XGT (800 nM, using culture medium solidified with 6 g.L-1agar. Arabidopsis thaliana L. seeds germinated in Petri plates for 4 to 5 days were transferred to culture media containing the different concentrations of XGs and cultured in a growing room. When the plantlets were cultured in a liquid medium, their growth was very slow in the presence of XGC and XGCH at the highest concentration tested, and it was faster at the lowest concentration. In the semi-solid culture medium, XGs also reduced growth. It was concluded that XGs can play a biological role in Arabidopsis thaliana (L. Heynh. plantlets, stimulating or inhibiting the root system growth and the lateral root formation. These opposite effects varied according to the plant specie that furnished the seeds containing XG, as well as the place where the seeds were collected, to the XG form used (hydrolyzed or not and to its concentration in the culture media. 

  5. High throughput selection of novel plant growth regulators: Assessing the translatability of small bioactive molecules from Arabidopsis to crops.

    Science.gov (United States)

    Rodriguez-Furlán, Cecilia; Miranda, Giovanna; Reggiardo, Martín; Hicks, Glenn R; Norambuena, Lorena

    2016-04-01

    Plant growth regulators (PGRs) have become an integral part of agricultural and horticultural practices. Accordingly, there is an increased demand for new and cost-effective products. Nevertheless, the market is limited by insufficient innovation. In this context chemical genomics has gained increasing attention as a powerful approach addressing specific traits. Here is described the successful implementation of a highly specific, sensitive and efficient high throughput screening approach using Arabidopsis as a model. Using a combination of techniques, 10,000 diverse compounds were screened and evaluated for several important plant growth traits including root and leaf growth. The phenotype-based selection allowed the compilation of a collection of putative Arabidopsis growth regulators with a broad range of activities and specificities. A subset was selected for evaluating their bioactivity in agronomically valuable plants. Their validation as growth regulators in commercial species such as tomato, lettuce, carrot, maize and turfgrasses reinforced the success of the screening in Arabidopsis and indicated that small molecules activity can be efficiently translated to commercial species. Therefore, the chemical genomics approach in Arabidopsis is a promising field that can be incorporated in PGR discovery programs and has a great potential to develop new products that can be efficiently used in crops. PMID:26940491

  6. Reconciling root plasticity and architectural ground rules in tree root growth models with voxel automata

    OpenAIRE

    Mulia, Rachmat; Dupraz, Christian; van Noordwijk, Meine

    2010-01-01

    Dynamic models of tree root growth and function have to reconcile the architectural rules for coarse root topology with the dynamics of fine root growth (and decay) in order to predict the strategic plus opportunistic behaviour of a tree root system in a heterogeneous soil. We present an algorithm for a 3D model based on both local (soil voxel level) and global (tree level) controls of root growth, with development of structural roots as a consequence of fine root function, rather than as dri...

  7. The acquisition of cell fate in the Arabidopsis thaliana root meristem

    OpenAIRE

    Scheres, B.J.G.; Berg, C. van den; Hage, W.; Willemsen, V; Werff, N. van der; Wolkenfelt, H.; McKhann, H.; Weisbeek, P.

    1997-01-01

    During plant embryogenesis an embryo with cotyledons, a shoot apical meristem, a hypocotyl and a root apical meristem, is formed. The primary root and shoot meristems initiate post-embryonic growth generating all plant organs. The root meristem forms the primary root, and the shoot meristem forms the aerial portion of the plant including secondary meristems. Histological and fate map data have shown that there is no precise correlation between the shoot meristem cells and their descendants. T...

  8. Secondary growth of the Arabidopsis hypocotyl-vascular development in dimensions.

    Science.gov (United States)

    Lehmann, Fabio; Hardtke, Christian S

    2016-02-01

    The secondary thickening of plant organs in extant dicotyledons is a massive growth process that constitutes the major carbon sink in perennial, woody plants. Yet, our understanding of its molecular genetic control has been mostly obtained by its analysis in an herbaceous annual model, Arabidopsis. Recent years have seen increased interest in this somewhat under-researched topic, and various (non-)cell autonomous factors that guide the extent and vascular patterning of secondary growth have been identified. Concomitantly, a more detailed understanding of vascular differentiation processes has been obtained through analyses of primary growth, mostly in the root meristem. A future challenge will be the integration of these patterning and differentiation modules together with cambial activity into the 4-dimensional frame of secondary thickening. PMID:26667498

  9. Belowground neighbor perception in Arabidopsis thaliana studied by transcriptome analysis: roots of Hieracium pilosella cause biotic stress.

    Science.gov (United States)

    Schmid, Christoph; Bauer, Sibylle; Müller, Benedikt; Bartelheimer, Maik

    2013-01-01

    Root-root interactions are much more sophisticated than previously thought, yet the mechanisms of belowground neighbor perception remain largely obscure. Genome-wide transcriptome analyses allow detailed insight into plant reactions to environmental cues. A root interaction trial was set up to explore both morphological and whole genome transcriptional responses in roots of Arabidopsis thaliana in the presence or absence of an inferior competitor, Hieracium pilosella. Neighbor perception was indicated by Arabidopsis roots predominantly growing away from the neighbor (segregation), while solitary plants placed more roots toward the middle of the pot. Total biomass remained unaffected. Database comparisons in transcriptome analysis revealed considerable similarity between Arabidopsis root reactions to neighbors and reactions to pathogens. Detailed analyses of the functional category "biotic stress" using MapMan tools found the sub-category "pathogenesis-related proteins" highly significantly induced. A comparison to a study on intraspecific competition brought forward a core of genes consistently involved in reactions to neighbor roots. We conclude that beyond resource depletion roots perceive neighboring roots or their associated microorganisms by a relatively uniform mechanism that involves the strong induction of pathogenesis-related proteins. In an ecological context the findings reveal that belowground neighbor detection may occur independently of resource depletion, allowing for a time advantage for the root to prepare for potential interactions. PMID:23967000

  10. A novel high efficiency, low maintenance, hydroponic system for synchronous growth and flowering of Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Bernier Georges

    2003-01-01

    Full Text Available Abstract Background Arabidopsis thaliana is now the model organism for genetic and molecular plant studies, but growing conditions may still impair the significance and reproducibility of the experimental strategies developed. Besides the use of phytotronic cabinets, controlling plant nutrition may be critical and could be achieved in hydroponics. The availability of such a system would also greatly facilitate studies dealing with root development. However, because of its small size and rosette growth habit, Arabidopsis is hardly grown in standard hydroponic devices and the systems described in the last years are still difficult to transpose at a large scale. Our aim was to design and optimize an up-scalable device that would be adaptable to any experimental conditions. Results An hydroponic system was designed for Arabidopsis, which is based on two units: a seed-holder and a 1-L tank with its cover. The original agar-containing seed-holder allows the plants to grow from sowing to seed set, without transplanting step and with minimal waste. The optimum nitrate supply was determined for vegetative growth, and the flowering response to photoperiod and vernalization was characterized to show the feasibility and reproducibility of experiments extending over the whole life cycle. How this equipment allowed to overcome experimental problems is illustrated by the analysis of developmental effects of nitrate reductase deficiency in nia1nia2 mutants. Conclusion The hydroponic device described in this paper allows to drive small and large scale cultures of homogeneously growing Arabidopsis plants. Its major advantages are its flexibility, easy handling, fast maintenance and low cost. It should be suitable for many experimental purposes.

  11. Genetic analysis of growth-regulator-induced parthenocarpy in Arabidopsis.

    Science.gov (United States)

    Vivian-Smith, A; Koltunow, A M

    1999-10-01

    In Arabidopsis, seedless silique development or parthenocarpy can be induced by the application of various plant growth regulators (PGRs) to unfertilized pistils. Ecotype-specific responses were observed in the Arabidopsis ecotypes Columbia and Landsberg relative to the type of PGR and level applied. The parthenocarpic response was greatest in ecotype Landsberg, and comparisons of fruit growth and morphology were studied primarily in this ecotype. Gibberellic acid application (10 micromol pistil(-1)) caused development similar to that in pollinated pistils, while benzyladenine (1 micromol pistil(-1)) and naphthylacetic acid (10 micromol pistil(-1)) treatment produced shorter siliques. Naphthylacetic acid primarily modified mesocarp cell expansion. Arabidopsis mutants were employed to examine potential dependencies on gibberellin biosynthesis (ga1-3, ga4-1, and ga5-1) and perception (spy-4 and gai) during parthenocarpic silique development. Emasculated spy-4 pistils were neither obviously parthenocarpic nor deficient in PGR perception. By contrast, emasculated gai mutants did not produce parthenocarpic siliques following gibberellic acid application, but silique development occurred following pollination or application of auxin and cytokinin. Pollinated gai siliques had decreased cell numbers and morphologically resembled auxin-induced parthenocarpic siliques. This shows that a number of independent and possibly redundant pathways can direct hormone-induced parthenocarpy, and that endogenous gibberellins play a role in regulating cell expansion and promoting cell division in carpels. PMID:10517835

  12. Plastid sedimentation kinetics in roots of wild-type and starch-deficient mutants of Arabidopsis

    Science.gov (United States)

    MacCleery, S. A.; Kiss, J. Z.

    1999-01-01

    Sedimentation and movement of plastids in columella cells of the root cap were measured in seedlings of wild-type, a reduced starch mutant, and a starchless mutant of Arabidopsis. To assay for sedimentation, we used both linear measurements and the change of angle from the cell center as indices in vertical and reoriented plants with the aid of computer-assisted image analysis. Seedlings were fixed at short periods after reorientation, and plastid sedimentation correlated with starch content in the three strains of Arabidopsis. Amyloplasts of wild-type seedlings showed the greatest sedimentation, whereas plastids of the starchless mutant showed no significant sedimentation in the vertically grown and reoriented seedlings. Because previous research has shown that a full complement of starch is needed for full gravitropic sensitivity, this study correlates increased sensitivity with plastid sedimentation. However, although plastid sedimentation contributed to gravisensitivity, it was not required, because the gravitropic starchless mutant had plastids that did not sediment. This is the first study, to our knowledge, to measure plastid sedimentation in Arabidopsis roots after reorientation of seedlings. Taken together, the results of this study are consistent with the classic plastid-based and protoplast-based models of graviperception and suggest that multiple systems of perception exist in plant cells.

  13. Changes in cell ultrastructure and morphology of Arabidopsis thaliana roots after coumarins treatment

    Directory of Open Access Journals (Sweden)

    Ewa Kupidłowska

    2014-02-01

    Full Text Available The ultrastructure and morphology of roots treated with coumarin and umbelliferone as well as the reversibility of the coumarins effects caused by exogenous GA, were studied in Arabidopsis thaliana. Both coumarins suppressed root elongation and appreciably stimulated radial expansion of epidermal and cortical cells in the upper part of the meristem and in the elongation zone. The gibberellic acid applied simultaneously with coumarins decreased their inhibitory effect on root elongation and reduced cells swelling.Microscopic observation showed intensive vacuolization of cells and abnormalities in the structure of the Golgi stacks and the nuclear envelope. The detection of active acid phosphatase in the cytosol of swollen cells indicated increased membrane permeability. Significant abnormalities of newly formed cell walls, e.g. the discontinuity of cellulose layer, uncorrect position of walls and the lack of their bonds with the mother cell wall suggest that coumarins affected the cytoskeleton.

  14. Calcium dynamics in root cells of Arabidopsis thaliana visualized with selective plane illumination microscopy.

    Directory of Open Access Journals (Sweden)

    Alex Costa

    Full Text Available Selective Plane Illumination Microscopy (SPIM is an imaging technique particularly suited for long term in-vivo analysis of transparent specimens, able to visualize small organs or entire organisms, at cellular and eventually even subcellular resolution. Here we report the application of SPIM in Calcium imaging based on Förster Resonance Energy Transfer (FRET. Transgenic Arabidopsis plants expressing the genetically encoded-FRET-based Ca(2+ probe Cameleon, in the cytosol or nucleus, were used to demonstrate that SPIM enables ratiometric fluorescence imaging at high spatial and temporal resolution, both at tissue and single cell level. The SPIM-FRET technique enabled us to follow nuclear and cytosolic Ca(2+ dynamics in Arabidopsis root tip cells, deep inside the organ, in response to different stimuli. A relevant physiological phenomenon, namely Ca(2+ signal percolation, predicted in previous studies, has been directly visualized.

  15. Cyclic mononucleotides modulate potassium and calcium flux responses to H2O2 in Arabidopsis roots

    KAUST Repository

    Ordoñez, Natalia Maria

    2014-02-13

    Cyclic mononucleotides are messengers in plant stress responses. Here we show that hydrogen peroxide (H2O2) induces rapid net K+-efflux and Ca2+-influx in Arabidopsis roots. Pre-treatment with either 10 μM cAMP or cGMP for 1 or 24 h does significantly reduce net K+-leakage and Ca2+-influx, and in the case of the K+-fluxes, the cell permeant cyclic mononucleotides are more effective. We also examined the effect of 10 μM of the cell permeant 8-Br-cGMP on the Arabidopsis microsomal proteome and noted a specific increase in proteins with a role in stress responses and ion transport, suggesting that cGMP is sufficient to directly and/or indirectly induce complex adaptive changes to cellular stresses induced by H2O2. © 2014 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  16. Redirection of auxin flow in Arabidopsis thaliana roots after infection by root-knot nematodes

    NARCIS (Netherlands)

    Kyndt, Tina; Goverse, Aska; Haegeman, Annelies; Warmerdam, Sonja; Wanjau, Cecilia; Jahani, Mona; Engler, Gilbert; Almeida Engler, De Janice; Gheysen, Godelieve

    2016-01-01

    Plant-parasitic root-knot nematodes induce the formation of giant cells within the plant root, and it has been recognized that auxin accumulates in these feeding sites. Here, we studied the role of the auxin transport system governed by AUX1/LAX3 influx proteins and different PIN efflux proteins dur

  17. Aluminium toxicity targets PIN2 in Arabidopsis root apices: Effects on PIN2 endocytosis, vesicular recycling,and polar auxin transport

    Institute of Scientific and Technical Information of China (English)

    SHEN Hong; HOU NingYan; Markus SCHLICHT; WAN YingLang; Stefano MANCUSO; Frantisek BALUSKA

    2008-01-01

    The most obvious symptom of AI toxicity is the inhibition of root growth.However,the mechanism of AI-inhibiting root growth remains to be elucidated.In this study,auxin transport and vesicle movement of an auxin-efflux carrier (PIN2) were investigated in Arabidopsis roots in response to AI stress.Results indicated that AI inhibited the apical transport of auxin in root tips of Arabidopsis significantly.The severe inhibition was localized in the cells of transition zone,where the concentration of auxin was only 34% that of the control.Brefeldin A (BFA),an inhibitor of vesicle transport,induced the dot-like structure of PIN2 vesicle significantly.Al decreased the size of dot-like structure of PIN2 vesicles.Re-sults of real-time RT-PCR and Western-blotting analysis showed that Al increased the transcript level of PIN2 and the accumulation of PIN2 protein in horizontal direction of plasma membrane,but decreased its distribution in endosomes,suggesting that AI inhibited the transport of PIN2 vesicles from plasma membrane to endosomes.Results of cytoskeleton-depolymering drugs indicated that it was via the pathway of disruption of actin microfilaments that AI inhibited the transport of PIN2 vesicles.Exposed to AI stress,the cells of elongation zone had less AI uptake and less transport frequency of vesicles than cells of transition zone.Taken together,our results suggested that AI inhibited root growth mainly by modulating the transport of PIN2 vesicles between plasma membrane and endosomes,thus block-ing auxin transport and root growth.

  18. Plant growth in Arabidopsis is assisted by compost soil-derived microbial communities.

    Science.gov (United States)

    Carvalhais, Lilia C; Muzzi, Frederico; Tan, Chin-Hong; Hsien-Choo, Jin; Schenk, Peer M

    2013-01-01

    Plants in natural and agricultural environments are continuously exposed to a plethora of diverse microorganisms resulting in microbial colonization of roots and the rhizosphere. This process is believed to be accompanied by an intricate network of ongoing simultaneous interactions. In this study, we examined Arabidopsis thaliana roots and shoots in the presence or absence of whole microbial communities extracted from compost soil. The results show a clear growth promoting effect on Arabidopsis shoots in the presence of soil microbes compared to plants grown in microbe-free soil under otherwise identical conditions. Element analyses showed that iron uptake was facilitated by these mixed microbial communities which also led to transcriptional downregulation of genes required for iron transport. In addition, soil microbial communities suppressed the expression of marker genes involved in nitrogen uptake, oxidative stress/redox signaling, and salicylic acid (SA)-mediated plant defense while upregulating jasmonate (JA) signaling, cell wall organization/biosynthesis and photosynthesis. Multi-species analyses such as simultaneous transcriptional profiling of plants and their interacting microorganisms (metatranscriptomics) coupled to metagenomics may further increase our understanding of the intricate networks underlying plant-microbe interactions. PMID:23847639

  19. Insight into the early steps of root hair formation revealed by the procuste1 cellulose synthase mutant of Arabidopsis thaliana

    OpenAIRE

    Singh Manoj; Fischer Urs; Singh Sunil K; Grebe Markus; Marchant Alan

    2008-01-01

    Abstract Background Formation of plant root hairs originating from epidermal cells involves selection of a polar initiation site and production of an initial hair bulge which requires local cell wall loosening. In Arabidopsis the polar initiation site is located towards the basal end of epidermal cells. However little is currently understood about the mechanism for the selection of the hair initiation site or the mechanism by which localised hair outgrowth is achieved. The Arabidopsis procust...

  20. 土壤食细菌线虫对拟南芥根系生长的影响及机理%The impact of bacterial-feeding nematodes on root growth of Arabidopsis thaliana L.and the possible mechanisms

    Institute of Scientific and Technical Information of China (English)

    成艳红; 陈小云; 刘满强; 胡锋; 李辉信

    2011-01-01

    hormonal effects as seen for protozoan grazing.To study the impacts andmechanisms of bacterial-feeding nematodes on the growth of plant, namely Arabidopsis thaliana L. ( Ecotype Columbia ) , a selected soil sample (sandy-loam alluvial soil) was mixed with pig manure and placed in mesh bags. In order to get greater populations of bacterial-feeding nematodes (SMI ) , the diameters of the openings were lmm and 5 μm. Then the mesh bags were buried under the soil ( SM5 ) which was surrounded with outer layer of un-amended soil seedlings. Nematodes were able to migrate through the 1 mm diameter mesh bag into the outer soil, thus giving greater populations than the soil surrounded by a control treatment with the mesh bag openings 5 jxm in diameter, through which nematodes could not migrate.After 35 days incubation, the outer soil contained a 4. 1-fold increase of nematode numbers in the lmm treatment compared to the 5μm treatment. The root parameters (total length, average diameter, total surface area and number of tips) of the seedlings grown in the outer soil were measured after 15 days. Soil NH^-N and NO3-N contents were determined using a continuous flow auto-analyzer ( AA3, Germany). Soil auxins were measured using high performance liquid chromatography ( HPLC). Soil bacterial community structure was analyzed by a Community-level physiological profile (CLPP) , using Biolog ECO microplates (Biolog, Hayward, CA, USA).Results showed that the Arabidopsis thaliana seedlings grown in the soil with more bacterial-feeding nematodes ( SMI ) could develop a highly branched root system with longer roots and bigger surface area. Soil NH^-N and auxin ( GA3 and IAA) contents were increased significantly in the presence of more nematodes. Furthermore, the potential for utilization of substrates of the Biolog system obtained by BIOLOG ecoplate assay indicated that the presence of nematodes made large differences in the catabolic capability of soil microbial communities. The mechanism was

  1. The role of auxin and cytokinin signalling in specifying the root architecture of Arabidopsis thaliana

    KAUST Repository

    Muraro, Daniele

    2013-01-01

    Auxin and cytokinin are key hormonal signals that control the cellular architecture of the primary root and the initiation of new lateral root organs in the plant Arabidopsis thaliana. Both developmental processes are regulated by cross-talk between these hormones and their signalling pathways. In this paper, sub-cellular and multi-cellular mathematical models are developed to investigate how interactions between auxin and cytokinin influence the size and location of regions of division and differentiation within the primary root, and describe how their cross-regulation may cause periodic branching of lateral roots. We show how their joint activity may influence tissue-specific oscillations in gene expression, as shown in Moreno-Risueno et al. (2010) and commented upon in Traas and Vernoux (2010), and we propose mechanisms that may generate synchronisation of such periodic behaviours inside a cell and with its neighbours. Using a multi-cellular model, we also analyse the roles of cytokinin and auxin in specifying the three main regions of the primary root (elongation, transition and division zones), our simulation results being in good agreement with independent experimental observations. We then use our model to generate testable predictions concerning the effect of varying the concentrations of the auxin efflux transporters on the sizes of the different root regions. In particular, we predict that over-expression of the transporters will generate a longer root with a longer elongation zone and a smaller division zone than that of a wild type root. This root will contain fewer cells than its wild type counterpart. We conclude that our model can provide a useful tool for investigating the response of cell division and elongation to perturbations in hormonal signalling. © 2012 Elsevier Ltd.

  2. Carotenoid crystal formation in Arabidopsis and carrot roots caused by increased phytoene synthase protein levels.

    Directory of Open Access Journals (Sweden)

    Dirk Maass

    Full Text Available BACKGROUND: As the first pathway-specific enzyme in carotenoid biosynthesis, phytoene synthase (PSY is a prime regulatory target. This includes a number of biotechnological approaches that have successfully increased the carotenoid content in agronomically relevant non-green plant tissues through tissue-specific PSY overexpression. We investigated the differential effects of constitutive AtPSY overexpression in green and non-green cells of transgenic Arabidopsis lines. This revealed striking similarities to the situation found in orange carrot roots with respect to carotenoid amounts and sequestration mechanism. METHODOLOGY/PRINCIPAL FINDINGS: In Arabidopsis seedlings, carotenoid content remained unaffected by increased AtPSY levels although the protein was almost quantitatively imported into plastids, as shown by western blot analyses. In contrast, non-photosynthetic calli and roots overexpressing AtPSY accumulated carotenoids 10 and 100-fold above the corresponding wild-type tissues and contained 1800 and 500 microg carotenoids per g dry weight, respectively. This increase coincided with a change of the pattern of accumulated carotenoids, as xanthophylls decreased relative to beta-carotene and carotene intermediates accumulated. As shown by polarization microscopy, carotenoids were found deposited in crystals, similar to crystalline-type chromoplasts of non-green tissues present in several other taxa. In fact, orange-colored carrots showed a similar situation with increased PSY protein as well as carotenoid levels and accumulation patterns whereas wild white-rooted carrots were similar to Arabidopsis wild type roots in this respect. Initiation of carotenoid crystal formation by increased PSY protein amounts was further confirmed by overexpressing crtB, a bacterial PSY gene, in white carrots, resulting in increased carotenoid amounts deposited in crystals. CONCLUSIONS: The sequestration of carotenoids into crystals can be driven by the

  3. Root and shoot performance of Arabidopsis thaliana exposed to elevated CO2: A physiologic, metabolic and transcriptomic response.

    Science.gov (United States)

    Jauregui, Iván; Aparicio-Tejo, Pedro M; Avila, Concepción; Rueda-López, Marina; Aranjuelo, Iker

    2015-09-15

    The responsiveness of C3 plants to raised atmospheric [CO2] levels has been frequently described as constrained by photosynthetic downregulation. The main goal of the current study was to characterize the shoot-root relationship and its implications in plant responsiveness under elevated [CO2] conditions. For this purpose, Arabidopsis thaliana plants were exposed to elevated [CO2] (800ppm versus 400ppm [CO2]) and fertilized with a mixed (NH4NO3) nitrogen source. Plant growth, physiology, metabolite and transcriptomic characterizations were carried out at the root and shoot levels. Plant growth under elevated [CO2] conditions was doubled due to increased photosynthetic rates and gas exchange measurements revealed that these plants maintain higher photosynthetic rates over extended periods of time. This positive response of photosynthetic rates to elevated [CO2] was caused by the maintenance of leaf protein and Rubisco concentrations at control levels alongside enhanced energy efficiency. The increased levels of leaf carbohydrates, organic acids and amino acids supported the augmented respiration rates of plants under elevated [CO2]. A transcriptomic analysis allowed the identification of photoassimilate allocation and remobilization as fundamental process used by the plants to maintain the outstanding photosynthetic performance. Moreover, based on the relationship between plant carbon status and hormone functioning, the transcriptomic analyses provided an explanation of why phenology accelerates under elevated [CO2] conditions. PMID:26519814

  4. Apoplastic Alkalinization Is Instrumental for the Inhibition of Cell Elongation in the Arabidopsis Root by the Ethylene Precursor 1-Aminocyclopropane-1-Carboxylic Acid

    NARCIS (Netherlands)

    Staal, Marten; De Cnodder, Tinne; Simon, Damien; Vandenbussche, Filip; Van Der Straeten, Dominique; Verbelen, Jean-Pierre; Elzenga, Theo; Vissenberg, Kris

    2011-01-01

    In Arabidopsis (Arabidopsis thaliana; Columbia-0) roots, the so-called zone of cell elongation comprises two clearly different domains: the transition zone, a postmeristematic region (approximately 200-450 mu m proximal of the root tip) with a low rate of elongation, and a fast elongation zone, the

  5. A gene regulatory network for root epidermis cell differentiation in Arabidopsis.

    Directory of Open Access Journals (Sweden)

    Angela Bruex

    2012-01-01

    Full Text Available The root epidermis of Arabidopsis provides an exceptional model for studying the molecular basis of cell fate and differentiation. To obtain a systems-level view of root epidermal cell differentiation, we used a genome-wide transcriptome approach to define and organize a large set of genes into a transcriptional regulatory network. Using cell fate mutants that produce only one of the two epidermal cell types, together with fluorescence-activated cell-sorting to preferentially analyze the root epidermis transcriptome, we identified 1,582 genes differentially expressed in the root-hair or non-hair cell types, including a set of 208 "core" root epidermal genes. The organization of the core genes into a network was accomplished by using 17 distinct root epidermis mutants and 2 hormone treatments to perturb the system and assess the effects on each gene's transcript accumulation. In addition, temporal gene expression information from a developmental time series dataset and predicted gene associations derived from a Bayesian modeling approach were used to aid the positioning of genes within the network. Further, a detailed functional analysis of likely bHLH regulatory genes within the network, including MYC1, bHLH54, bHLH66, and bHLH82, showed that three distinct subfamilies of bHLH proteins participate in root epidermis development in a stage-specific manner. The integration of genetic, genomic, and computational analyses provides a new view of the composition, architecture, and logic of the root epidermal transcriptional network, and it demonstrates the utility of a comprehensive systems approach for dissecting a complex regulatory network.

  6. Identification and characterization of inward K ~+-channels in plasma membranes of Arabidopsis root cortex cells

    Institute of Scientific and Technical Information of China (English)

    于川江; 武维华

    1999-01-01

    Patch clamping whole-cell reeording techniques were apphed to study the inward K+ channels in Arabidopsis root cortex cells. The inward K+-channels in the plasma membranes of the root cortex cell protoplasts were activated by hyperpolarized membrane potentials. The channels were highly selective tor K+ ions over Na+ ions. The channel activity was significantly inbibited by the external TEA(?) or Ba(?) The changes in cytoplasmic Ca2+ concentrations did not affect the whole-cell inward K+-currents. The possible asso(?)ation betw(?)en the channel selectivity to K+ and Na(?) ions and plant salt-tolerance was also discussed.

  7. Comprehensive transcriptional profiling of NaCl-stressed Arabidopsis roots reveals novel classes of responsive genes

    Directory of Open Access Journals (Sweden)

    Deyholos Michael K

    2006-10-01

    Full Text Available Abstract Background Roots are an attractive system for genomic and post-genomic studies of NaCl responses, due to their primary importance to agriculture, and because of their relative structural and biochemical simplicity. Excellent genomic resources have been established for the study of Arabidopsis roots, however, a comprehensive microarray analysis of the root transcriptome following NaCl exposure is required to further understand plant responses to abiotic stress and facilitate future, systems-based analyses of the underlying regulatory networks. Results We used microarrays of 70-mer oligonucleotide probes representing 23,686 Arabidopsis genes to identify root transcripts that changed in relative abundance following 6 h, 24 h, or 48 h of hydroponic exposure to 150 mM NaCl. Enrichment analysis identified groups of structurally or functionally related genes whose members were statistically over-represented among up- or down-regulated transcripts. Our results are consistent with generally observed stress response themes, and highlight potentially important roles for underappreciated gene families, including: several groups of transporters (e.g. MATE, LeOPT1-like; signalling molecules (e.g. PERK kinases, MLO-like receptors, carbohydrate active enzymes (e.g. XTH18, transcription factors (e.g. members of ZIM, WRKY, NAC, and other proteins (e.g. 4CL-like, COMT-like, LOB-Class 1. We verified the NaCl-inducible expression of selected transcription factors and other genes by qRT-PCR. Conclusion Micorarray profiling of NaCl-treated Arabidopsis roots revealed dynamic changes in transcript abundance for at least 20% of the genome, including hundreds of transcription factors, kinases/phosphatases, hormone-related genes, and effectors of homeostasis, all of which highlight the complexity of this stress response. Our identification of these transcriptional responses, and groups of evolutionarily related genes with either similar or divergent

  8. Low-pH and aluminum resistance in arabidopsis correlates with high cytosolic magnesium content and increased magnesium uptake by plant roots.

    Science.gov (United States)

    Bose, Jayakumar; Babourina, Olga; Shabala, Sergey; Rengel, Zed

    2013-07-01

    Low-pH stress and Al(3+) toxicity affect root growth in acid soils. It was hypothesized that the capacity of genotypes to maintain Mg(2+) uptake in acidic environments may contribute to low-pH and Al resistance, but explicit evidence is lacking. In this work, an Al-resistant alr104 mutant and two Al-sensitive mutants (als5 and als3) of Arabidopsis thaliana were compared with the wild type (Col-0) for Mg(2+) uptake and intracellular Mg(2+) concentration under low-pH and combined low-pH/Al stresses. Magnesium accumulation in roots was measured in long-term (7 d) experiments. The Mg(2+) fluxes were measured using ion-sensitive microelectrodes at the distal elongation and the mature root zones in short-term (0-60 min) experiments. Intracellular Mg(2+) concentrations were measured in intact root cells at the distal elongation zone using magnesium-specific fluorescent dye and fluorescent lifetime imaging (FLIM) analysis. Under low-pH stress, Arabidopsis mutants als5 and alr104 maintained a higher Mg concentration in roots, and had greater Mg(2+) influx than the wild type and the als3 mutant. Under combined low-pH/Al treatment, Al-resistant genotypes (wild type and alr104) maintained a higher Mg(2+) accumulation, and had a higher Mg(2+) influx and higher intracellular Mg(2+) concentration than Al-sensitive genotypes (als3 and als5). Overall, these results show that increased Mg(2+) uptake correlates with an enhanced capacity of Arabidopsis genotypes to cope with low-pH and combined low-pH/Al stresses. PMID:23620479

  9. Natural variation of root exudates in Arabidopsis thaliana-linking metabolomic and genomic data.

    Science.gov (United States)

    Mönchgesang, Susann; Strehmel, Nadine; Schmidt, Stephan; Westphal, Lore; Taruttis, Franziska; Müller, Erik; Herklotz, Siska; Neumann, Steffen; Scheel, Dierk

    2016-01-01

    Many metabolomics studies focus on aboveground parts of the plant, while metabolism within roots and the chemical composition of the rhizosphere, as influenced by exudation, are not deeply investigated. In this study, we analysed exudate metabolic patterns of Arabidopsis thaliana and their variation in genetically diverse accessions. For this project, we used the 19 parental accessions of the Arabidopsis MAGIC collection. Plants were grown in a hydroponic system, their exudates were harvested before bolting and subjected to UPLC/ESI-QTOF-MS analysis. Metabolite profiles were analysed together with the genome sequence information. Our study uncovered distinct metabolite profiles for root exudates of the 19 accessions. Hierarchical clustering revealed similarities in the exudate metabolite profiles, which were partly reflected by the genetic distances. An association of metabolite absence with nonsense mutations was detected for the biosynthetic pathways of an indolic glucosinolate hydrolysis product, a hydroxycinnamic acid amine and a flavonoid triglycoside. Consequently, a direct link between metabolic phenotype and genotype was detected without using segregating populations. Moreover, genomics can help to identify biosynthetic enzymes in metabolomics experiments. Our study elucidates the chemical composition of the rhizosphere and its natural variation in A. thaliana, which is important for the attraction and shaping of microbial communities. PMID:27363486

  10. PHABULOSA controls the quiescent center-independent root meristem activities in Arabidopsis thaliana.

    Directory of Open Access Journals (Sweden)

    Jose Sebastian

    2015-03-01

    Full Text Available Plant growth depends on stem cell niches in meristems. In the root apical meristem, the quiescent center (QC cells form a niche together with the surrounding stem cells. Stem cells produce daughter cells that are displaced into a transit-amplifying (TA domain of the root meristem. TA cells divide several times to provide cells for growth. SHORTROOT (SHR and SCARECROW (SCR are key regulators of the stem cell niche. Cytokinin controls TA cell activities in a dose-dependent manner. Although the regulatory programs in each compartment of the root meristem have been identified, it is still unclear how they coordinate one another. Here, we investigate how PHABULOSA (PHB, under the posttranscriptional control of SHR and SCR, regulates TA cell activities. The root meristem and growth defects in shr or scr mutants were significantly recovered in the shr phb or scr phb double mutant, respectively. This rescue in root growth occurs in the absence of a QC. Conversely, when the modified PHB, which is highly resistant to microRNA, was expressed throughout the stele of the wild-type root meristem, root growth became very similar to that observed in the shr; however, the identity of the QC was unaffected. Interestingly, a moderate increase in PHB resulted in a root meristem phenotype similar to that observed following the application of high levels of cytokinin. Our protoplast assay and transgenic approach using ARR10 suggest that the depletion of TA cells by high PHB in the stele occurs via the repression of B-ARR activities. This regulatory mechanism seems to help to maintain the cytokinin homeostasis in the meristem. Taken together, our study suggests that PHB can dynamically regulate TA cell activities in a QC-independent manner, and that the SHR-PHB pathway enables a robust root growth system by coordinating the stem cell niche and TA domain.

  11. Cinnamic Acid Increases Lignin Production and Inhibits Soybean Root Growth

    OpenAIRE

    Victor Hugo Salvador; Rogério Barbosa Lima; Wanderley Dantas dos Santos; Anderson Ricardo Soares; Paulo Alfredo Feitoza Böhm; Rogério Marchiosi; Maria de Lourdes Lucio Ferrarese; Osvaldo Ferrarese-Filho

    2013-01-01

    Cinnamic acid is a known allelochemical that affects seed germination and plant root growth and therefore influences several metabolic processes. In the present work, we evaluated its effects on growth, indole-3-acetic acid (IAA) oxidase and cinnamate 4-hydroxylase (C4H) activities and lignin monomer composition in soybean ( Glycine max ) roots. The results revealed that exogenously applied cinnamic acid inhibited root growth and increased IAA oxidase and C4H activities. The allelochemical in...

  12. Plant growth-promoting rhizobacteria and root system functioning

    OpenAIRE

    Vacheron, Jordan; Desbrosses, Guilhem; Bouffaud, Marie-Lara; Touraine, Bruno; Moënne-Loccoz, Yvan; Muller, Daniel; Legendre, Laurent; Wisniewski-Dyé, Florence; Prigent-Combaret, Claire

    2013-01-01

    The rhizosphere supports the development and activity of a huge and diversified microbial community, including microorganisms capable to promote plant growth. Among the latter, plant growth-promoting rhizobacteria (PGPR) colonize roots of monocots and dicots, and enhance plant growth by direct and indirect mechanisms. Modification of root system architecture by PGPR implicates the production of phytohormones and other signals that lead, mostly, to enhanced lateral root branching and developme...

  13. Plant growth-promoting rhizobacteria and root system functioning

    OpenAIRE

    Jordan eVacheron; Guilhem eDesbrosses; Marie-Lara eBouffaud; Bruno eTouraine; Yvan eMoënne-Loccoz; Daniel eMuller; Laurent eLegendre; Florence eWisniewski-Dyé; Claire ePrigent-Combaret

    2013-01-01

    The rhizosphere supports the development and activity of a huge and diversified microbial community, including microorganisms capable to promote plant growth. Among the latter, Plant Growth-Promoting Rhizobacteria (PGPR) colonize roots of monocots and dicots, and enhance plant growth by direct and indirect mechanisms. Modification of root system architecture by PGPR implicates the production of phytohormones and other signals that lead, mostly, to enhanced lateral root branching and developme...

  14. Root exudation of phytochemicals in Arabidopsis follows specific patterns that are developmentally programmed and correlate with soil microbial functions.

    Directory of Open Access Journals (Sweden)

    Jacqueline M Chaparro

    Full Text Available Plant roots constantly secrete compounds into the soil to interact with neighboring organisms presumably to gain certain functional advantages at different stages of development. Accordingly, it has been hypothesized that the phytochemical composition present in the root exudates changes over the course of the lifespan of a plant. Here, root exudates of in vitro grown Arabidopsis plants were collected at different developmental stages and analyzed using GC-MS. Principle component analysis revealed that the composition of root exudates varied at each developmental stage. Cumulative secretion levels of sugars and sugar alcohols were higher in early time points and decreased through development. In contrast, the cumulative secretion levels of amino acids and phenolics increased over time. The expression in roots of genes involved in biosynthesis and transportation of compounds represented in the root exudates were consistent with patterns of root exudation. Correlation analyses were performed of the in vitro root exudation patterns with the functional capacity of the rhizosphere microbiome to metabolize these compounds at different developmental stages of Arabidopsis grown in natural soils. Pyrosequencing of rhizosphere mRNA revealed strong correlations (p<0.05 between microbial functional genes involved in the metabolism of carbohydrates, amino acids and secondary metabolites with the corresponding compounds released by the roots at particular stages of plant development. In summary, our results suggest that the root exudation process of phytochemicals follows a developmental pattern that is genetically programmed.

  15. Root Exudation of Phytochemicals in Arabidopsis Follows Specific Patterns That Are Developmentally Programmed and Correlate with Soil Microbial Functions

    Science.gov (United States)

    Sugiyama, Akifumi; Manter, Daniel K.; Vivanco, Jorge M.

    2013-01-01

    Plant roots constantly secrete compounds into the soil to interact with neighboring organisms presumably to gain certain functional advantages at different stages of development. Accordingly, it has been hypothesized that the phytochemical composition present in the root exudates changes over the course of the lifespan of a plant. Here, root exudates of in vitro grown Arabidopsis plants were collected at different developmental stages and analyzed using GC-MS. Principle component analysis revealed that the composition of root exudates varied at each developmental stage. Cumulative secretion levels of sugars and sugar alcohols were higher in early time points and decreased through development. In contrast, the cumulative secretion levels of amino acids and phenolics increased over time. The expression in roots of genes involved in biosynthesis and transportation of compounds represented in the root exudates were consistent with patterns of root exudation. Correlation analyses were performed of the in vitro root exudation patterns with the functional capacity of the rhizosphere microbiome to metabolize these compounds at different developmental stages of Arabidopsis grown in natural soils. Pyrosequencing of rhizosphere mRNA revealed strong correlations (p<0.05) between microbial functional genes involved in the metabolism of carbohydrates, amino acids and secondary metabolites with the corresponding compounds released by the roots at particular stages of plant development. In summary, our results suggest that the root exudation process of phytochemicals follows a developmental pattern that is genetically programmed. PMID:23383346

  16. Strigolactone regulates anthocyanin accumulation, acid phosphatases production and plant growth under low phosphate condition in Arabidopsis.

    Directory of Open Access Journals (Sweden)

    Shinsaku Ito

    Full Text Available Phosphate is an essential macronutrient in plant growth and development; however, the concentration of inorganic phosphate (Pi in soil is often suboptimal for crop performance. Accordingly, plants have developed physiological strategies to adapt to low Pi availability. Here, we report that typical Pi starvation responses in Arabidopsis are partially dependent on the strigolactone (SL signaling pathway. SL treatment induced root hair elongation, anthocyanin accumulation, activation of acid phosphatase, and reduced plant weight, which are characteristic responses to phosphate starvation. Furthermore, the expression profile of SL-response genes correlated with the expression of genes induced by Pi starvation. These results suggest a potential overlap between SL signaling and Pi starvation signaling pathways in plants.

  17. The relationship between leaf area growth and biomass accumulation in Arabidopsis thaliana.

    Science.gov (United States)

    Weraduwage, Sarathi M; Chen, Jin; Anozie, Fransisca C; Morales, Alejandro; Weise, Sean E; Sharkey, Thomas D

    2015-01-01

    Leaf area growth determines the light interception capacity of a crop and is often used as a surrogate for plant growth in high-throughput phenotyping systems. The relationship between leaf area growth and growth in terms of mass will depend on how carbon is partitioned among new leaf area, leaf mass, root mass, reproduction, and respiration. A model of leaf area growth in terms of photosynthetic rate and carbon partitioning to different plant organs was developed and tested with Arabidopsis thaliana L. Heynh. ecotype Columbia (Col-0) and a mutant line, gigantea-2 (gi-2), which develops very large rosettes. Data obtained from growth analysis and gas exchange measurements was used to train a genetic programming algorithm to parameterize and test the above model. The relationship between leaf area and plant biomass was found to be non-linear and variable depending on carbon partitioning. The model output was sensitive to the rate of photosynthesis but more sensitive to the amount of carbon partitioned to growing thicker leaves. The large rosette size of gi-2 relative to that of Col-0 resulted from relatively small differences in partitioning to new leaf area vs. leaf thickness. PMID:25914696

  18. Finding missing interactions of the Arabidopsis thaliana root stem cell niche gene regulatory network

    Directory of Open Access Journals (Sweden)

    Eugenio eAzpeitia

    2013-04-01

    Full Text Available AbstractOver the last few decades, the Arabidopsis thaliana root stem cell niche has become a model system for the study of plant development and the stem cell niche. Currently, many of the molecular mechanisms involved in root stem cell niche maintenance and development have been described. A few years ago, we published a gene regulatory network model integrating this information. This model suggested that there were missing components or interactions. Upon updating the model, the observed stable gene configurations of the root stem cell niche could not be recovered, indicating that there are additional missing components or interactions in the model. In fact, due to the lack of experimental data, gene regulatory networks inferred from published data are usually incomplete. However, predicting the location and nature of the missing data is a not trivial task. Here, we propose a set of procedures for detecting and predicting missing interactions in Boolean networks. We used these procedures to predict putative missing interactions in the A. thaliana root stem cell niche network model. Using our approach, we identified three necessary interactions to recover the reported gene activation configurations that have been experimentally uncovered for the different cell types within the root stem cell niche: 1 a regulation of PHABULOSA to restrict its expression domain to the vascular cells, 2 a self-regulation of WOX5, possibly by an indirect mechanism through the auxin signalling pathway and 3 a positive regulation of JACKDAW by MAGPIE. The procedures proposed here greatly reduce the number of possible Boolean functions that are biologically meaningful and experimentally testable and that do not contradict previous data. We believe that these procedures can be used on any Boolean network. However, because the procedures were designed for the specific case of the root stem cell niche, formal demonstrations of the procedures should be shown in future

  19. Transcriptomic Analysis of Soil-Grown Arabidopsis thaliana Roots and Shoots in Response to a Drought Stress

    OpenAIRE

    Sultana eRasheed; Khurram eBashir; Akihiro eMatsui; Maho eTanaka; Motoaki eSeki

    2016-01-01

    Drought stress has a negative impact on crop yield. Thus, understanding the molecular mechanisms responsible for plant drought stress tolerance is essential for improving this beneficial trait in crops. In the current study, a transcriptional analysis was conducted of gene regulatory networks in roots of soil-grown Arabidopsis plants in response to a drought stress treatment. A microarray analysis of drought-stressed roots and shoots was performed at 0, 1, 3, 5, 7 and 9 days. Results indicat...

  20. Glycosylation of a Fasciclin-Like Arabinogalactan-Protein (SOS5) Mediates Root Growth and Seed Mucilage Adherence via a Cell Wall Receptor-Like Kinase (FEI1/FEI2) Pathway in Arabidopsis

    OpenAIRE

    Basu, Debarati; Tian, Lu; Debrosse, Tayler; Poirier, Emily; Emch, Kirk; Herock, Hayley; Travers, Andrew; Showalter, Allan M.

    2016-01-01

    Fundamental processes that underpin plant growth and development depend crucially on the action and assembly of the cell wall, a dynamic structure that changes in response to both developmental and environmental cues. While much is known about cell wall structure and biosynthesis, much less is known about the functions of the individual wall components, particularly with respect to their potential roles in cellular signaling. Loss-of-function mutants of two arabinogalactan-protein (AGP)-speci...

  1. Colonization of Arabidopsis roots by Pseudomonas fluorescens primes the plant to produce higher levels of ethylene upon pathogen infection

    NARCIS (Netherlands)

    Hase, S.; Pelt, J.A. van; Loon, L.C. van; Pieterse, C.M.J.

    2003-01-01

    Plants develop an enhanced defensive capacity against a broad spectrum of plant pathogens after colonization of the roots by selected strains of non-pathogenic, fluorescent Pseudomonas spp. In Arabidopsis thaliana, this rhizobacteria-induced systemic resistance (ISR) functions independently of salic

  2. Identification of genes involved in the ACC-mediated control of root cell elongation in Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Markakis Marios

    2012-11-01

    Full Text Available Abstract Background Along the root axis of Arabidopsis thaliana, cells pass through different developmental stages. In the apical meristem repeated cycles of division increase the numbers of cells. Upon leaving the meristem, these cells pass the transition zone where they are physiologically and mechanically prepared to undergo subsequent rapid elongation. During the process of elongation epidermal cells increase their length by 300% in a couple of hours. When elongation ceases, the cells acquire their final size, shape and functions (in the differentiation zone. Ethylene administered as its precursor 1-aminocyclopropane-1-carboxylic acid (ACC is capable of inhibiting elongation in a concentration-dependent way. Using a microarray analysis, genes and/or processes involved in this elongation arrest are identified. Results Using a CATMA-microarray analysis performed on control and 3h ACC-treated roots, 240 differentially expressed genes were identified. Quantitative Real-Time RT-PCR analysis of the 10 most up and down regulated genes combined with literature search confirmed the accurateness of the analysis. This revealed that inhibition of cell elongation is, at least partly, caused by restricting the events that under normal growth conditions initiate elongation and by increasing the processes that normally stop cellular elongation at the end of the elongation/onset of differentiation zone. Conclusions ACC interferes with cell elongation in the Arabidopsis thaliana roots by inhibiting cells from entering the elongation process and by immediately stimulating the formation of cross-links in cell wall components, diminishing the remaining elongation capacity. From the analysis of the differentially expressed genes, it becomes clear that many genes identified in this response, are also involved in several other kind of stress responses. This suggests that many responses originate from individual elicitors, but that somewhere in the downstream

  3. Root growth, secondary root formation and root gravitropism in carotenoid-deficient seedlings of Zea mays L

    Science.gov (United States)

    Ng, Y. K.; Moore, R.

    1985-01-01

    The effect of ABA on root growth, secondary-root formation and root gravitropism in seedlings of Zea mays was investigated by using Fluridone-treated seedlings and a viviparous mutant, both of which lack carotenoids and ABA. Primary roots of seedlings grown in the presence of Fluridone grew significantly slower than those of control (i.e. untreated) roots. Elongation of Fluridone-treated roots was inhibited significantly by the exogenous application of 1 mM ABA. Exogenous application of 1 micromole and 1 nmole ABA had either no effect or only a slight stimulatory effect on root elongation, depending on the method of application. The absence of ABA in Fluridone-treated plants was not an important factor in secondary-root formation in seedlings less than 9-10 d old. However, ABA may suppress secondary-root formation in older seedlings, since 11-d-old control seedlings had significantly fewer secondary roots than Fluridone-treated seedlings. Roots of Fluridone-treated and control seedlings were graviresponsive. Similar data were obtained for vp-9 mutants of Z. mays, which are phenotypically identical to Fluridone-treated seedlings. These results indicate that ABA is necessary for neither secondary-root formation nor for positive gravitropism by primary roots.

  4. Potential involvement of drought-induced Ran GTPase CLRan1 in root growth enhancement in a xerophyte wild watermelon.

    Science.gov (United States)

    Akashi, Kinya; Yoshimura, Kazuya; Kajikawa, Masataka; Hanada, Kouhei; Kosaka, Rina; Kato, Atsushi; Katoh, Akira; Nanasato, Yoshihiko; Tsujimoto, Hisashi; Yokota, Akiho

    2016-10-01

    Enhanced root growth is known as the survival strategy of plants under drought. Previous proteome analysis in drought-resistant wild watermelon has shown that Ran GTPase, an essential regulator of cell division and proliferation, was induced in the roots under drought. In this study, two cDNAs were isolated from wild watermelon, CLRan1 and CLRan2, which showed a high degree of structural similarity with those of other plant Ran GTPases. Quantitative RT-PCR and promoter-GUS assays suggested that CLRan1 was expressed mainly in the root apex and lateral root primordia, whereas CLRan2 was more broadly expressed in other part of the roots. Immunoblotting analysis confirmed that the abundance of CLRan proteins was elevated in the root apex region under drought stress. Transgenic Arabidopsis overexpressing CLRan1 showed enhanced primary root growth, and the growth was maintained under osmotic stress, indicating that CLRan1 functions as a positive factor for maintaining root growth under stress conditions. PMID:27310473

  5. Perturbation of cytokinin and ethylene-signalling pathways explain the strong rooting phenotype exhibited by Arabidopsis expressing the Schizosaccharomyces pombe mitotic inducer, cdc25

    Directory of Open Access Journals (Sweden)

    Spadafora Natasha D

    2012-03-01

    Full Text Available Abstract Background Entry into mitosis is regulated by cyclin dependent kinases that in turn are phosphoregulated. In most eukaryotes, phosphoregulation is through WEE1 kinase and CDC25 phosphatase. In higher plants a homologous CDC25 gene is unconfirmed and hence the mitotic inducer Schizosaccharomyces pombe (Sp cdc25 has been used as a tool in transgenic plants to probe cell cycle function. Expression of Spcdc25 in tobacco BY-2 cells accelerates entry into mitosis and depletes cytokinins; in whole plants it stimulates lateral root production. Here we show, for the first time, that alterations to cytokinin and ethylene signaling explain the rooting phenotype elicited by Spcdc25 expression in Arabidopsis. Results Expressing Spcdc25 in Arabidopsis results in increased formation of lateral and adventitious roots, a reduction of primary root width and more isodiametric cells in the root apical meristem (RAM compared with wild type. Furthermore it stimulates root morphogenesis from hypocotyls when cultured on two way grids of increasing auxin and cytokinin concentrations. Microarray analysis of seedling roots expressing Spcdc25 reveals that expression of 167 genes is changed by > 2-fold. As well as genes related to stress responses and defence, these include 19 genes related to transcriptional regulation and signaling. Amongst these was the up-regulation of genes associated with ethylene synthesis and signaling. Seedlings expressing Spcdc25 produced 2-fold more ethylene than WT and exhibited a significant reduction in hypocotyl length both in darkness or when exposed to 10 ppm ethylene. Furthermore in Spcdc25 expressing plants, the cytokinin receptor AHK3 was down-regulated, and endogenous levels of iPA were reduced whereas endogeous IAA concentrations in the roots increased. Conclusions We suggest that the reduction in root width and change to a more isodiametric cell phenotype in the RAM in Spcdc25 expressing plants is a response to ethylene over

  6. An ABA down-regulated bHLH transcription repressor gene, bHLH129 regulates root elongation and ABA response when overexpressed in Arabidopsis

    Science.gov (United States)

    Tian, Hainan; Guo, Hongyan; Dai, Xuemei; Cheng, Yuxin; Zheng, Kaijie; Wang, Xiaoping; Wang, Shucai

    2015-01-01

    Plant hormone abscisic acid (ABA) plays a crucial role in modulating plant responses to environmental stresses. Basic helix-loop-helix (bHLH) transcription factors are one of the largest transcription factor families that regulate multiple aspects of plant growth and development, as well as of plant metabolism in Arabidopsis. Several bHLH transcription factors have been shown to be involved in the regulation of ABA signaling. We report here the characterization of bHLH129, a bHLH transcription factor in Arabidopsis. We found that the expression level of bHLH129 was reduced in response to exogenously applied ABA, and elevated in the ABA biosynthesis mutant aba1-5. Florescence observation of transgenic plants expressing bHLH129-GFP showed that bHLH129 was localized in the nucleus, and transient expression of bHLH129 in protoplasts inhibited reporter gene expression. When expressed in Arabidopsis under the control of the 35S promoter, bHLH129 promoted root elongation, and the transgenic plants were less sensitivity to ABA in root elongation assays. Quantitative RT-PCR results showed that ABA response of several genes involved in ABA signaling, including ABI1, SnRK2.2, SnRK2.3 and SnRK2.6 were altered in the transgenic plants overexpressing bHLH129. Taken together, our study suggests that bHLH129 is a transcription repressor that negatively regulates ABA response in Arabidopsis. PMID:26625868

  7. Separation of ballistic and diffusive fluorescence photons in confocal Light-Sheet Microscopy of Arabidopsis roots

    Science.gov (United States)

    Meinert, Tobias; Tietz, Olaf; Palme, Klaus J.; Rohrbach, Alexander

    2016-01-01

    Image quality in light-sheet fluorescence microscopy is strongly affected by the shape of the illuminating laser beam inside embryos, plants or tissue. While the phase of Gaussian or Bessel beams propagating through thousands of cells can be partly controlled holographically, the propagation of fluorescence light to the detector is difficult to control. With each scatter process a fluorescence photon loses information necessary for the image generation. Using Arabidopsis root tips we demonstrate that ballistic and diffusive fluorescence photons can be separated by analyzing the image spectra in each plane without a priori knowledge. We introduce a theoretical model allowing to extract typical scattering parameters of the biological material. This allows to attenuate image contributions from diffusive photons and to amplify the relevant image contributions from ballistic photons through a depth dependent deconvolution. In consequence, image contrast and resolution are significantly increased and scattering artefacts are minimized especially for Bessel beams with confocal line detection. PMID:27553506

  8. Separation of ballistic and diffusive fluorescence photons in confocal Light-Sheet Microscopy of Arabidopsis roots.

    Science.gov (United States)

    Meinert, Tobias; Tietz, Olaf; Palme, Klaus J; Rohrbach, Alexander

    2016-01-01

    Image quality in light-sheet fluorescence microscopy is strongly affected by the shape of the illuminating laser beam inside embryos, plants or tissue. While the phase of Gaussian or Bessel beams propagating through thousands of cells can be partly controlled holographically, the propagation of fluorescence light to the detector is difficult to control. With each scatter process a fluorescence photon loses information necessary for the image generation. Using Arabidopsis root tips we demonstrate that ballistic and diffusive fluorescence photons can be separated by analyzing the image spectra in each plane without a priori knowledge. We introduce a theoretical model allowing to extract typical scattering parameters of the biological material. This allows to attenuate image contributions from diffusive photons and to amplify the relevant image contributions from ballistic photons through a depth dependent deconvolution. In consequence, image contrast and resolution are significantly increased and scattering artefacts are minimized especially for Bessel beams with confocal line detection. PMID:27553506

  9. Photosynthate Regulation of the Root System Architecture Mediated by the Heterotrimeric G Protein Complex in Arabidopsis.

    Science.gov (United States)

    Mudgil, Yashwanti; Karve, Abhijit; Teixeira, Paulo J P L; Jiang, Kun; Tunc-Ozdemir, Meral; Jones, Alan M

    2016-01-01

    Assimilate partitioning to the root system is a desirable developmental trait to control but little is known of the signaling pathway underlying partitioning. A null mutation in the gene encoding the Gβ subunit of the heterotrimeric G protein complex, a nexus for a variety of signaling pathways, confers altered sugar partitioning in roots. While fixed carbon rapidly reached the roots of wild type and agb1-2 mutant seedlings, agb1 roots had more of this fixed carbon in the form of glucose, fructose, and sucrose which manifested as a higher lateral root density. Upon glucose treatment, the agb1-2 mutant had abnormal gene expression in the root tip validated by transcriptome analysis. In addition, PIN2 membrane localization was altered in the agb1-2 mutant. The heterotrimeric G protein complex integrates photosynthesis-derived sugar signaling incorporating both membrane-and transcriptional-based mechanisms. The time constants for these signaling mechanisms are in the same range as photosynthate delivery to the root, raising the possibility that root cells are able to use changes in carbon fixation in real time to adjust growth behavior. PMID:27610112

  10. The Root Cap Determines Ethylene-Dependent Growth and Development in Maize Roots

    Institute of Scientific and Technical Information of China (English)

    Achim Hahn; Roman Zimmermann; Dierk Wanke; Klaus Harter; Hans G.Edelmann

    2008-01-01

    Besides providing protection against mechanical damage to the root tip,the root cap is involved in the perception and processing of diverse external and internal stimuli resulting in altered growth and development.The transduction of these stimuli includes hormonal signaling pathways such as those of auxin,ethylene and cytokinin.Here,we show that the root cap is essential for the ethylene-induced regulation of elongation growth and root hair formation in maize.Exogenously applied ethylene is no longer able to inhibit elongation growth when the root cap has been surgically removed prior to hormone treatment.Reconstitution of the cap positively correlates with the developing capacity of the roots to respond to ethylene again.In contrast,the removal of the root cap does not per se affect growth inhibition controlled by auxin and cytokinin.Furthermore,our semi-quantitative RT-PCR results support earlier findings that the maize root cap is a site of high gene expression activity with respect to sensing and responding to hormones such as ethylene.From these data,we propose a novel function of the root cap which is the establishment of competence to respond to ethylene in the distal zones of the root.

  11. Cortical microtubule patterning in roots of Arabidopsis thaliana primary cell wall mutants reveals the bidirectional interplay with cell expansion.

    Science.gov (United States)

    Panteris, Emmanuel; Adamakis, Ioannis-Dimosthenis S; Daras, Gerasimos; Rigas, Stamatis

    2015-01-01

    Cell elongation requires directional deposition of cellulose microfibrils regulated by transverse cortical microtubules. Microtubules respond differentially to suppression of cell elongation along the developmental zones of Arabidopsis thaliana root apex. Cortical microtubule orientation is particularly affected in the fast elongation zone but not in the meristematic or transition zones of thanatos and pom2-4 cellulose-deficient mutants of Arabidopsis thaliana. Here, we report that a uniform phenotype is established among the primary cell wall mutants, as cortical microtubules of root epidermal cells of rsw1 and prc1 mutants exhibit the same pattern described in thanatos and pom2-4. Whether cortical microtubules assume transverse orientation or not is determined by the demand for cellulose synthesis, according to each root zone's expansion rate. It is suggested that cessation of cell expansion may provide a biophysical signal resulting in microtubule reorientation. PMID:26042727

  12. Mathematical modeling and experimental validation of the spatial distribution of boron in the root of Arabidopsis thaliana identify high boron accumulation in the tip and predict a distinct root tip uptake function.

    Science.gov (United States)

    Shimotohno, Akie; Sotta, Naoyuki; Sato, Takafumi; De Ruvo, Micol; Marée, Athanasius F M; Grieneisen, Verônica A; Fujiwara, Toru

    2015-04-01

    Boron, an essential micronutrient, is transported in roots of Arabidopsis thaliana mainly by two different types of transporters, BORs and NIPs (nodulin26-like intrinsic proteins). Both are plasma membrane localized, but have distinct transport properties and patterns of cell type-specific accumulation with different polar localizations, which are likely to affect boron distribution. Here, we used mathematical modeling and an experimental determination to address boron distributions in the root. A computational model of the root is created at the cellular level, describing the boron transporters as observed experimentally. Boron is allowed to diffuse into roots, in cells and cell walls, and to be transported over plasma membranes, reflecting the properties of the different transporters. The model predicts that a region around the quiescent center has a higher concentration of soluble boron than other portions. To evaluate this prediction experimentally, we determined the boron distribution in roots using laser ablation-inductivity coupled plasma-mass spectrometry. The analysis indicated that the boron concentration is highest near the tip and is lower in the more proximal region of the meristem zone, similar to the pattern of soluble boron distribution predicted by the model. Our model also predicts that upward boron flux does not continuously increase from the root tip toward the mature region, indicating that boron taken up in the root tip is not efficiently transported to shoots. This suggests that root tip-absorbed boron is probably used for local root growth, and that instead it is the more mature root regions which have a greater role in transporting boron toward the shoots. PMID:25670713

  13. Auxin transport and growth in intact roots of Vicia faba

    International Nuclear Information System (INIS)

    Transport of IAA applied to the intact root of Vicia seedlings was investigated in relation to root growth. The root was treated at 3-4,4-5 or 7-8mm from the tip with a narrow ring of lanolin paste containing IAA or IAA-2-14C in growth or transport experiments, repectively. The growth process along the root axis was examined in every 1-mm part from the tip at 30 min, 1 or 4 hr intervals. The elongation zone of the control root was 1-9mm from the tip. IAA treatment brought about no significant change in the growth of the region apical to the treated site, whereas distinct inhibition of growth occurred in the region basal to the treated site within 1 hr. The transport of radioactivity was observed in both acropetal and basipetal directions within 1 hr, but the later predominated for 8 hr or more; the nearer to the tip the treatment site, the longer the predominance lasted. The velocities of acropetal and basipetal transport were estimated at about 4 and 8 mm/hr, respectively. Autoradiographs of transverse section of roots showed that basipetal transport occurred mainly through the outer part of the root, whereas acropetal transport occurred mainly through the inner part, the central cylinder. It may be concluded that the basipetally transported IAA which passed cylinder. It may be concluded that the basipetally transported IAA which passed through the outer part of the root inhibited the elongation of the intact root. (auth.)

  14. A Complex Molecular Interplay of Auxin and Ethylene Signaling Pathways Is Involved in Arabidopsis Growth Promotion by Burkholderia phytofirmans PsJN

    Science.gov (United States)

    Poupin, María J.; Greve, Macarena; Carmona, Vicente; Pinedo, Ignacio

    2016-01-01

    Modulation of phytohormones homeostasis is one of the proposed mechanisms to explain plant growth promotion induced by beneficial rhizobacteria (PGPR). However, there is still limited knowledge about the molecular signals and pathways underlying these beneficial interactions. Even less is known concerning the interplay between phytohormones in plants inoculated with PGPR. Auxin and ethylene are crucial hormones in the control of plant growth and development, and recent studies report an important and complex crosstalk between them in the regulation of different plant developmental processes. The objective of this work was to study the role of both hormones in the growth promotion of Arabidopsis thaliana plants induced by the well-known PGPR Burkholderia phytofirmans PsJN. For this, the spatiotemporal expression patterns of several genes related to auxin biosynthesis, perception and response and ethylene biosynthesis were studied, finding that most of these genes showed specific transcriptional regulations after inoculation in roots and shoots. PsJN-growth promotion was not observed in Arabidopsis mutants with an impaired ethylene (ein2-1) or auxin (axr1–5) signaling. Even, PsJN did not promote growth in an ethylene overproducer (eto2), indicating that a fine regulation of both hormones signaling and homeostasis is necessary to induce growth of the aerial and root tissues. Auxin polar transport is also involved in growth promotion, since PsJN did not promote primary root growth in the pin2 mutant or under chemical inhibition of transport in wild type plants. Finally, a key role for ethylene biosynthesis was found in the PsJN-mediated increase in root hair number. These results not only give new insights of PGPR regulation of plant growth but also are also useful to understand key aspects of Arabidopsis growth control.

  15. A complex molecular interplay of auxin and ethylene signaling pathways is involved in Arabidopsis growth promotion by Burkholderia phytofirmans PsJN

    Directory of Open Access Journals (Sweden)

    María Josefina Poupin

    2016-04-01

    Full Text Available Modulation of phytohormones homeostasis is one of the proposed mechanisms to explain plant growth promotion induced by beneficial rhizobacteria (PGPR. However, there is still limited knowledge about the molecular signals and pathways underlying these beneficial interactions. Even less is known concerning the interplay between phytohormones in plants inoculated with PGPR. Auxin and ethylene are crucial hormones in the control of plant growth and development, and recent studies report an important and complex crosstalk between them in the regulation of different plant developmental processes. The objective of this work was to study the role of both hormones in the growth promotion of Arabidopsis thaliana plants induced by the well-known PGPR Burkholderia phytofirmans PsJN. For this, the spatiotemporal expression patterns of several genes related to auxin biosynthesis, perception and response and ethylene biosynthesis were studied, finding that most of these genes showed specific transcriptional regulations after inoculation in roots and shoots. PsJN-growth promotion was not observed in Arabidopsis mutants with an impaired ethylene (ein2-1 or auxin (axr1-5 signaling. Even, PsJN did not promote growth in an ethylene overproducer (eto2, indicating that a fine regulation of both hormones signaling and homeostasis is necessary to induce growth of the aerial and root tissues. Auxin polar transport is also involved in growth promotion, since PsJN did not promote primary root growth in the pin2 mutant or under chemical inhibition of transport in wild type plants. Finally, a key role for ethylene biosynthesis was found in the PsJN-mediated increase in root hair number. These results not only give new insights of PGPR regulation of plant growth but also are also useful to understand key aspects of Arabidopsis growth control.

  16. A Complex Molecular Interplay of Auxin and Ethylene Signaling Pathways Is Involved in Arabidopsis Growth Promotion by Burkholderia phytofirmans PsJN.

    Science.gov (United States)

    Poupin, María J; Greve, Macarena; Carmona, Vicente; Pinedo, Ignacio

    2016-01-01

    Modulation of phytohormones homeostasis is one of the proposed mechanisms to explain plant growth promotion induced by beneficial rhizobacteria (PGPR). However, there is still limited knowledge about the molecular signals and pathways underlying these beneficial interactions. Even less is known concerning the interplay between phytohormones in plants inoculated with PGPR. Auxin and ethylene are crucial hormones in the control of plant growth and development, and recent studies report an important and complex crosstalk between them in the regulation of different plant developmental processes. The objective of this work was to study the role of both hormones in the growth promotion of Arabidopsis thaliana plants induced by the well-known PGPR Burkholderia phytofirmans PsJN. For this, the spatiotemporal expression patterns of several genes related to auxin biosynthesis, perception and response and ethylene biosynthesis were studied, finding that most of these genes showed specific transcriptional regulations after inoculation in roots and shoots. PsJN-growth promotion was not observed in Arabidopsis mutants with an impaired ethylene (ein2-1) or auxin (axr1-5) signaling. Even, PsJN did not promote growth in an ethylene overproducer (eto2), indicating that a fine regulation of both hormones signaling and homeostasis is necessary to induce growth of the aerial and root tissues. Auxin polar transport is also involved in growth promotion, since PsJN did not promote primary root growth in the pin2 mutant or under chemical inhibition of transport in wild type plants. Finally, a key role for ethylene biosynthesis was found in the PsJN-mediated increase in root hair number. These results not only give new insights of PGPR regulation of plant growth but also are also useful to understand key aspects of Arabidopsis growth control. PMID:27148317

  17. Arabidopsis thaliana cdd1 mutant uncouples the constitutive activation of salicylic acid signalling from growth defects

    NARCIS (Netherlands)

    Swain, S.; Roy, S.; Shah, J.; Wees, S.C.M. van; Pieterse, C.M.J.; Nandi, A.K.

    2011-01-01

    Arabidopsis genotypes with a hyperactive salicylic acidmediated signalling pathway exhibit enhanced disease resistance, which is often coupled with growth and developmental defects, such as dwarfing and spontaneous necrotic lesions on the leaves, resulting in reduced biomass yield. In this article,

  18. A proteomic approach to analyzing responses of Arabidopsis thaliana root cells to different gravitational conditions using an agravitropic mutant, pin2 and its wild type

    Directory of Open Access Journals (Sweden)

    Tan Chao

    2011-11-01

    Full Text Available Abstract Background Root gravitropsim has been proposed to require the coordinated, redistribution of the plant signaling molecule auxin within the root meristem, but the underlying molecular mechanisms are still unknown. PIN proteins are membrane transporters that mediate the efflux of auxin from cells. The PIN2 is important for the basipetal transport of auxin in roots and plays a critical role in the transmission of gravity signals perceived in the root cap to the root elongation zone. The loss of function pin2 mutant exhibits a gravity-insensitive root growth phenotype. By comparing the proteomes of wild type and the pin2 mutant root tips under different gravitational conditions, we hope to identify proteins involved in the gravity-related signal transduction. Results To identify novel proteins involved in the gravity signal transduction pathway we have carried out a comparative proteomic analysis of Arabidopsis pin2 mutant and wild type (WT roots subjected to different gravitational conditions. These conditions included horizontal (H and vertical (V clinorotation, hypergravity (G and the stationary control (S. Analysis of silver-stained two-dimensional SDS-PAGE gels revealed 28 protein spots that showed significant expression changes in altered gravity (H or G compared to control roots (V and S. Whereas the majority of these proteins exhibited similar expression patterns in WT and pin2 roots, a significant number displayed different patterns of response between WT and pin2 roots. The latter group included 11 protein spots in the H samples and two protein spots in the G samples that exhibited an altered expression exclusively in WT but not in pin2 roots. One of these proteins was identified as annexin2, which was induced in the root cap columella cells under altered gravitational conditions. Conclusions The most interesting observation in this study is that distinctly different patterns of protein expression were found in WT and pin2 mutant

  19. 生长素类化合物及6-苯甲基腺嘌呤对拟南芥主根生长的抑制效应比较%Comparison of the Inhibit Effects of Auxins and 6-Benzyladenine on Arabidopsis Main Root Growth

    Institute of Scientific and Technical Information of China (English)

    李晓峰; 孟广目; 梁城磊; 李丹; 张瑞婷; 牟长军; 陈倪; 刘恒

    2012-01-01

    To study the effect of auxins and 6-BA on cell divison and cell elongation, we compared the inhibit effects of 1AA, NAA, 2,4-D and 6-BA on Arabidopsis main root development. We found that IAA and NAA has similar effects on root development that can increases the length of root meristem zone through promotes cell division and decreases the length of root elongation zone, but 2,4-D and 6-BA decreases both the length of root meristem zone through inhibit cell division and root elongation zone.%为更好的研究生长素类化合物及6-苯甲基腺嘌呤(6-BA)对细胞分裂和细胞伸长的影响,以拟南芥主根为材料,从组织学水平比较了IAA、NAA、2,4-D和6-BA对拟南芥主根分生区和伸长区的抑制效应,发现IAA和NAA效果是相似的,可以通过促进细胞分裂显著增加根分生区长度,但也显著缩短主根伸长区长度,而2,4-D和6-BA则通过抑制细胞分裂来显著缩短根分生区长度,同时也显著缩短根伸长区的长度.

  20. Root Responses to Boron Deficiency Mediated by Ethylene

    OpenAIRE

    González-Fontes, Agustín; Herrera-Rodríguez, M. B.; Martín-Rejano, Esperanza M.; Navarro-Gochicoa, M. T.; Rexach, Jesús; Camacho-Cristóbal, Juan J.

    2016-01-01

    Low boron (B) supply alters the architecture of the root system in Arabidopsis thaliana seedlings, leading to a reduction in the primary root growth and an increase in the length and number of root hairs. At short-term (hours), B deficiency causes a decrease in the cell elongation of the primary root, resulting in a lower growth. Experimental approaches using ethylene insensitive Arabidopsis mutants, inhibitors of ethylene response, and GUS reporter lines suggest that ethylene is involved in ...

  1. Cytosolic Ca(2+) Signals Enhance the Vacuolar Ion Conductivity of Bulging Arabidopsis Root Hair Cells.

    Science.gov (United States)

    Wang, Yi; Dindas, Julian; Rienmüller, Florian; Krebs, Melanie; Waadt, Rainer; Schumacher, Karin; Wu, Wei-Hua; Hedrich, Rainer; Roelfsema, M Rob G

    2015-11-01

    Plant cell expansion depends on the uptake of solutes across the plasma membrane and their storage within the vacuole. In contrast to the well-studied plasma membrane, little is known about the regulation of ion transport at the vacuolar membrane. We therefore established an experimental approach to study vacuolar ion transport in intact Arabidopsis root cells, with multi-barreled microelectrodes. The subcellular position of electrodes was detected by imaging current-injected fluorescent dyes. Comparison of measurements with electrodes in the cytosol and vacuole revealed an average vacuolar membrane potential of -31 mV. Voltage clamp recordings of single vacuoles resolved the activity of voltage-independent and slowly deactivating channels. In bulging root hairs that express the Ca(2+) sensor R-GECO1, rapid elevation of the cytosolic Ca(2+) concentration was observed, after impalement with microelectrodes, or injection of the Ca(2+) chelator BAPTA. Elevation of the cytosolic Ca(2+) level stimulated the activity of voltage-independent channels in the vacuolar membrane. Likewise, the vacuolar ion conductance was enhanced during a sudden increase of the cytosolic Ca(2+) level in cells injected with fluorescent Ca(2+) indicator FURA-2. These data thus show that cytosolic Ca(2+) signals can rapidly activate vacuolar ion channels, which may prevent rupture of the vacuolar membrane, when facing mechanical forces. PMID:26232520

  2. Identification of a Stelar-Localized Transport Protein That Facilitates Root-to-Shoot Transfer of Chloride in Arabidopsis

    KAUST Repository

    Li, Bo

    2015-12-11

    Under saline conditions, higher plants restrict the accumulation of chloride ions (Cl–) in the shoot by regulating their transfer from the root symplast into the xylem-associated apoplast. To identify molecular mechanisms underpinning this phenomenon, we undertook a transcriptional screen of salt stressed Arabidopsis (Arabidopsis thaliana) roots. Microarrays, quantitative RT-PCR, and promoter-GUS fusions identified a candidate gene involved in Cl– xylem loading from the Nitrate transporter 1/Peptide Transporter family (NPF2.4). This gene was highly expressed in the root stele compared to the cortex, and its expression decreased after exposure to NaCl or abscisic acid. NPF2.4 fused to fluorescent proteins, expressed either transiently or stably, was targeted to the plasma membrane. Electrophysiological analysis of NPF2.4 in Xenopus laevis oocytes suggested that NPF2.4 catalyzed passive Cl– efflux out of cells and was much less permeable to NO3−. Shoot Cl– accumulation was decreased following NPF2.4 artificial microRNA knockdown, whereas it was increased by overexpression of NPF2.4. Taken together, these results suggest that NPF2.4 is involved in long-distance transport of Cl– in plants, playing a role in the loading and the regulation of Cl– loading into the xylem of Arabidopsis roots during salinity stress.

  3. Genes of the most conserved WOX clade in plants affect root and flower development in Arabidopsis

    Directory of Open Access Journals (Sweden)

    Moreau Hervé

    2008-10-01

    Full Text Available Abstract Background The Wuschel related homeobox (WOX family proteins are key regulators implicated in the determination of cell fate in plants by preventing cell differentiation. A recent WOX phylogeny, based on WOX homeodomains, showed that all of the Physcomitrella patens and Selaginella moellendorffii WOX proteins clustered into a single orthologous group. We hypothesized that members of this group might preferentially share a significant part of their function in phylogenetically distant organisms. Hence, we first validated the limits of the WOX13 orthologous group (WOX13 OG using the occurrence of other clade specific signatures and conserved intron insertion sites. Secondly, a functional analysis using expression data and mutants was undertaken. Results The WOX13 OG contained the most conserved plant WOX proteins including the only WOX detected in the highly proliferating basal unicellular and photosynthetic organism Ostreococcus tauri. A large expansion of the WOX family was observed after the separation of mosses from other land plants and before monocots and dicots have arisen. In Arabidopsis thaliana, AtWOX13 was dynamically expressed during primary and lateral root initiation and development, in gynoecium and during embryo development. AtWOX13 appeared to affect the floral transition. An intriguing clade, represented by the functional AtWOX14 gene inside the WOX13 OG, was only found in the Brassicaceae. Compared to AtWOX13, the gene expression profile of AtWOX14 was restricted to the early stages of lateral root formation and specific to developing anthers. A mutational insertion upstream of the AtWOX14 homeodomain sequence led to abnormal root development, a delay in the floral transition and premature anther differentiation. Conclusion Our data provide evidence in favor of the WOX13 OG as the clade containing the most conserved WOX genes and established a functional link to organ initiation and development in Arabidopsis, most

  4. Proteomic analyses of the interaction between the plant-growth promoting rhizobacterium Paenibacillus polymyxa E681 and Arabidopsis thaliana.

    Science.gov (United States)

    Kwon, Young Sang; Lee, Dong Yeol; Rakwal, Randeep; Baek, Seong-Bum; Lee, Jeom Ho; Kwak, Youn-Sig; Seo, Jong-Su; Chung, Woo Sik; Bae, Dong-Won; Kim, Sang Gon

    2016-01-01

    Plant growth-promoting rhizobacteria (PGPR) facilitate the plant growth and enhance their induced systemic resistance (ISR) against a variety of environmental stresses. In this study, we carried out integrative analyses on the proteome, transcriptome, and metabolome to investigate Arabidopsis root and shoot responses to the well-known PGPR strain Paenibacillus polymyxa (P. polymyxa) E681. Shoot fresh and root dry weights were increased, whereas root length was decreased by treatment with P. polymyxa E681. 2DE approach in conjunction with MALDI-TOF/TOF analysis revealed a total of 41 (17 spots in root, 24 spots in shoot) that were differentially expressed in response to P. polymyxa E681. Biological process- and molecular function-based bioinformatics analysis resulted in their classification into seven different protein groups. Of these, 36 proteins including amino acid metabolism, antioxidant, defense and stress response, photosynthesis, and plant hormone-related proteins were up-regulated, whereas five proteins including three carbohydrate metabolism- and one amino acid metabolism-related, and one unknown protein were down-regulated, respectively. A good correlation was observed between protein and transcript abundances for the 12 differentially expressed proteins during interactions as determined by qPCR analysis. Metabolite analysis using LC-MS/MS revealed highly increased levels of tryptophan, indole-3-acetonitrile (IAN), indole-3-acetic acid (IAA), and camalexin in the treated plants. Arabidopsis plant inoculated P. polymyxa E681 also showed resistance to Botrytis cinerea infection. Taken together these results suggest that P. polymyxa E681 may promote plant growth by induced metabolism and activation of defense-related proteins against fungal pathogen. PMID:26460066

  5. Transcriptional Activation and Production of Tryptophan-Derived Secondary Metabolites in Arabidopsis Roots Contributes to the Defense against the Fungal Vascular Pathogen Verticillium Iongisporum

    Institute of Scientific and Technical Information of China (English)

    Tim Iven; Wolfgang Dr(o)ge-Laser; Stefanie K(o)nig; Seema Singh; Susanna A.Braus-Stromeyer; Matthias Bischoff; Lutz F.Tietze; Gerhard H.Braus; Volker Lipka; Ivo Feussner

    2012-01-01

    The soil-borne fungal pathogen Verticillium Iongisporum causes vascular disease on Brassicaceae host plants such as oilseed rape.The fungus colonizes the root xylem and moves upwards to the foliage where disease symptoms become visible.Using Arabidopsis as a model for early gene induction,we performed root transcriptome analyses in response to hyphal growth immediately after spore germination and during penetration of the root cortex,respectively.Infected roots showed a rapid reprogramming of gene expression such as activation of transcription factors,stress-,and defense-related genes.Here,we focused on the highly coordinated gene induction resulting in the production of tryptophan-derived secondary metabolites.Previous studies in leaves showed that enzymes encoded by CYP81F2 and PEN2 (PENETRATION2) execute the formation of antifungal indole glucosinolate (IGS) metabolites.In Verticillium-infected roots.we found transcriptional activation of CYP81F2 and the PEN2 homolog PEL1 (PEN2-LIKE1),but no increase in antifungal IGS breakdown products.In contrast,indole-3-carboxylic acid (I3CA) and the phytoalexin camalexin accumulated in infected roots but only camalexin inhibited Verticillium growth in vitro.Whereas genetic disruption of the individual metabolic pathways leading to either camalexin or CYP81F2-dependent IGS metabolites did not alter Verticillium-induced disease symptoms,a cyp79b2 cyp79b3 mutant impaired in both branches resulted in significantly enhanced susceptibility.Hence,our data provide an insight into root-specific early defenses and suggest tryptophan-derived metabolites as active antifungal compounds against a vascular pathogen.

  6. Auxin-Independent NAC Pathway Acts in Response to Explant-Specific Wounding and Promotes Root Tip Emergence during de Novo Root Organogenesis in Arabidopsis.

    Science.gov (United States)

    Chen, Xiaodong; Cheng, Jingfei; Chen, Lyuqin; Zhang, Guifang; Huang, Hai; Zhang, Yijing; Xu, Lin

    2016-04-01

    Plants have powerful regenerative abilities that allow them to recover from damage and survive in nature. De novo organogenesis is one type of plant regeneration in which adventitious roots and shoots are produced from wounded and detached organs. By studying de novo root organogenesis using leaf explants of Arabidopsis (Arabidopsis thaliana), we previously suggested that wounding is the first event that provides signals to trigger the whole regenerative process. However, our knowledge of the role of wounding in regeneration remains limited. In this study, we show that wounding not only triggers the auxin-mediated fate transition of regeneration-competent cells, but also induces the NAC pathway for root tip emergence. The NAC1 transcription factor gene was specifically expressed in response to wounding in the leaf explant, but not in the wounded leaf residue of the source plant. Inhibition of the NAC1 pathway severely affected the emergence of adventitious root tips. However, the NAC1 pathway functioned independently of auxin-mediated cell fate transition and regulates expression of CEP genes, which encode proteins that might have a role in degradation of extensin proteins in the cell wall. Overall, our results suggest that wounding has multiple roles in de novo root organogenesis and that NAC1 acts as one downstream branch in regulating the cellular environment for organ emergence. PMID:26850273

  7. The Arabidopsis AtRaptor genes are essential for post-embryonic plant growth

    Directory of Open Access Journals (Sweden)

    Veit Bruce

    2005-04-01

    Full Text Available Abstract Background Flowering plant development is wholly reliant on growth from meristems, which contain totipotent cells that give rise to all post-embryonic organs in the plant. Plants are uniquely able to alter their development throughout their lifespan through the generation of new organs in response to external signals. To identify genes that regulate meristem-based growth, we considered homologues of Raptor proteins, which regulate cell growth in response to nutrients in yeast and metazoans as part of a signaling complex with the target of rapamycin (TOR kinase. Results We identified AtRaptor1A and AtRaptor1B, two loci predicted to encode Raptor proteins in Arabidopsis. Disruption of AtRaptor1B yields plants with a wide range of developmental defects: roots are thick and grow slowly, leaf initiation and bolting are delayed and the shoot inflorescence shows reduced apical dominance. AtRaptor1A AtRaptor1B double mutants show normal embryonic development but are unable to maintain post-embryonic meristem-driven growth. AtRaptor transcripts accumulate in dividing and expanding cells and tissues. Conclusion The data implicate the TOR signaling pathway, a major regulator of cell growth in yeast and metazoans, in the maintenance of growth from the shoot apical meristem in plants. These results provide insights into the ways in which TOR/Raptor signaling has been adapted to regulate plant growth and development, and indicate that in plants, as in other eukaryotes, there is some Raptor-independent TOR activity.

  8. An ethylene and ROS-dependent pathway is involved in low ammonium-induced root hair elongation in Arabidopsis seedlings.

    Science.gov (United States)

    Zhu, Changhua; Yang, Na; Guo, Zhengfei; Qian, Meng; Gan, Lijun

    2016-08-01

    Root hairs are plastic in response to nutrient supply, but relatively little is known about their development under low ammonium (NH4(+)) conditions. This study showed that reducing NH4(+) for 3 days in wild-type Arabidopsis seedlings resulted in drastic elongation of root hairs. To investigate the possible mediation of ethylene and auxin in this process, seedlings were treated with 2,3,5-triiodobenzoic acid (TIBA, auxin transport inhibitor), 1-naphthylphthalamic acid (NPA, auxin transport inhibitor), p-chlorophenoxy isobutyric acid (PCIB, auxin action inhibitor), aminoethoxyvinylglycine (AVG, chemical inhibitor of ethylene biosynthesis), or silver ions (Ag(+), ethylene perception antagonist) under low NH4(+) conditions. Our results showed that TIBA, NPA and PCIB did not inhibit root hair elongation under low NH4(+) conditions, while AVG and Ag(+) completely inhibited low NH4(+)-induced root hair elongation. This suggested that low NH4(+)-induced root hair elongation was dependent on the ethylene pathway, but not the auxin pathway. Further genetic studies revealed that root hair elongation in auxin-insensitive mutants was sensitive to low NH4(+) treatment, but elongation was less sensitive in ethylene-insensitive mutants than wild-type plants. In addition, low NH4(+)-induced root hair elongation was accompanied by reactive oxygen species (ROS) accumulation. Diphenylene iodonium (DPI, NADPH oxidase inhibitor) and dimethylthiourea (DMTU, ROS scavenger) inhibited low NH4(+)-induced root hair elongation, suggesting that ROS were involved in this process. Moreover, ethylene acted together with ROS to modulate root hair elongation under low NH4(+) conditions. These results demonstrate that a signaling pathway involving ethylene and ROS participates in regulation of root hair elongation when Arabidopsis seedlings are subjected to low NH4(+) conditions. PMID:27074220

  9. Jatropha curcas L. root structure and growth in diverse soils.

    Science.gov (United States)

    Valdés-Rodríguez, Ofelia Andrea; Sánchez-Sánchez, Odilón; Pérez-Vázquez, Arturo; Caplan, Joshua S; Danjon, Frédéric

    2013-01-01

    Unlike most biofuel species, Jatropha curcas has promise for use in marginal lands, but it may serve an additional role by stabilizing soils. We evaluated the growth and structural responsiveness of young J. curcas plants to diverse soil conditions. Soils included a sand, a sandy-loam, and a clay-loam from eastern Mexico. Growth and structural parameters were analyzed for shoots and roots, although the focus was the plasticity of the primary root system architecture (the taproot and four lateral roots). The sandy soil reduced the growth of both shoot and root systems significantly more than sandy-loam or clay-loam soils; there was particularly high plasticity in root and shoot thickness, as well as shoot length. However, the architecture of the primary root system did not vary with soil type; the departure of the primary root system from an index of perfect symmetry was 14 ± 5% (mean ± standard deviation). Although J. curcas developed more extensively in the sandy-loam and clay-loam soils than in sandy soil, it maintained a consistent root to shoot ratio and root system architecture across all types of soil. This strong genetic determination would make the species useful for soil stabilization purposes, even while being cultivated primarily for seed oil. PMID:23844412

  10. Jatropha curcas L. Root Structure and Growth in Diverse Soils

    Directory of Open Access Journals (Sweden)

    Ofelia Andrea Valdés-Rodríguez

    2013-01-01

    Full Text Available Unlike most biofuel species, Jatropha curcas has promise for use in marginal lands, but it may serve an additional role by stabilizing soils. We evaluated the growth and structural responsiveness of young J. curcas plants to diverse soil conditions. Soils included a sand, a sandy-loam, and a clay-loam from eastern Mexico. Growth and structural parameters were analyzed for shoots and roots, although the focus was the plasticity of the primary root system architecture (the taproot and four lateral roots. The sandy soil reduced the growth of both shoot and root systems significantly more than sandy-loam or clay-loam soils; there was particularly high plasticity in root and shoot thickness, as well as shoot length. However, the architecture of the primary root system did not vary with soil type; the departure of the primary root system from an index of perfect symmetry was 14±5% (mean ± standard deviation. Although J. curcas developed more extensively in the sandy-loam and clay-loam soils than in sandy soil, it maintained a consistent root to shoot ratio and root system architecture across all types of soil. This strong genetic determination would make the species useful for soil stabilization purposes, even while being cultivated primarily for seed oil.

  11. Auxin polar transport in arabidopsis under simulated microgravity conditions - relevance to growth and development

    Science.gov (United States)

    Miyamoto, K.; Oka, M.; Yamamoto, R.; Masuda, Y.; Hoson, T.; Kamisaka, S.; Ueda, J.

    1999-01-01

    Activity of auxin polar transport in inflorescence axes of Arabidopsis thaliana grown under simulated microgravity conditions was studied in relation to the growth and development. Seeds were germinated and allowed to grow on an agar medium in test tubes on a horizontal clinostat. Horizontal clinostat rotation substantially reduced the growth of inflorescence axes and the productivity of seeds of Arabidopsis thaliana (ecotypes Landsberg erecta and Columbia), although it little affected seed germination, development of rosette leaves and flowering. The activity of auxin polar transport in inflorescence axes decreased when Arabidopsis plants were grown on a horizontal clinostat from germination stage, being ca. 60% of 1 g control. On the other hand, the auxin polar transport in inflorescence axes of Arabidopsis grown in 1 g conditions was not affected when the segments were exposed to various gravistimuli, including 3-dimensional clinorotation, during transport experiments. Pin-formed mutant of Arabidopsis, having a unique structure of the inflorescence axis with no flower and extremely low levels of the activity of auxin polar transport in inflorescence axes and endogenous auxin, did not continue its vegetative growth under clinostat rotation. These facts suggest that the development of the system of auxin polar transport in Arabidopsis is affected by microgravity, resulting in the inhibition of growth and development, especially during reproductive growth.

  12. AtGRIP protein locates to the secretory vesicles of trans Golgi-network in Arabidopsis root cap cells

    Institute of Scientific and Technical Information of China (English)

    CHEN Ying; ZHANG Wei; ZHAO Lei; LI Yan

    2008-01-01

    GRIP domain proteins, locating to the trans-Golgi network, are thought to play an essential role in Golgi apparatus trafficking in yeast and animal cells. In the present study, AtGRIP cDNA was amplified by reverse transcriptase PCR from RNA isolated from Arabidopsis seedling. The GST fusion protein of AtGRIP was affinity-purified and its rabbit polyclonal antibody was obtained. Immuno-blotting with the purified anti-AtGRIP polyclonal antibody demonstrated that the molecular mass of AtGRIP protein is about 92 kD, and its expression is not tissue-specific in Arabidopsis. Immunoflourescent labeling and confocal microscopy revealed that the AtGRIP protein was co-localized with Golgi stacks in Arabidop-sis root cells. Immuno-gold labeling and electron microscopy observation showed that AtGRIP protein was mainly located to the membrane of the secretory vesicles of trans-Golgi network in Arabidopsis root cap cells. Taken together, these results indicate that the localization of GRIP domain proteins be-tween plants and animal cells are conserved. These results also suggest that the AtGRIP may be in-volved in regulating the formation or sorting of Golgi-associated vesicles in plant cells.

  13. Ectopic expression of Arabidopsis ABC transporter MRP7 modifies cadmium root-to-shoot transport and accumulation

    Energy Technology Data Exchange (ETDEWEB)

    Wojas, Sylwia [Faculty of Biology, University of Warsaw, Miecznikowa str. 1, 02-096 Warszawa (Poland); Hennig, Jacek [Institute of Biochemistry and Biophysics PAS, Pawinskiego str. 5A, 02-106 Warszawa (Poland); Plaza, Sonia; Geisler, Markus [Institute of Plant Biology, University of Zuerich, CH-8008 Zuerich (Switzerland); Siemianowski, Oskar; Sklodowska, Aleksandra [Faculty of Biology, University of Warsaw, Miecznikowa str. 1, 02-096 Warszawa (Poland); Ruszczynska, Anna; Bulska, Ewa [Faculty of Chemistry, University of Warsaw, Pasteura str.1, 02-093 Warszawa (Poland); Antosiewicz, Danuta M., E-mail: dma@biol.uw.edu.p [Faculty of Biology, University of Warsaw, Miecznikowa str. 1, 02-096 Warszawa (Poland)

    2009-10-15

    Arabidopsis MRPs/ABCCs have been shown to remove various organic and inorganic substrates from the cytosol to other subcellular compartments. Here we first demonstrate that heterologous expression of AtMRP7 in tobacco (Nicotiana tabacum var. Xanthi) modifies cadmium accumulation, distribution and tolerance. Arabidopsis MRP7 was localized both in the tonoplast and in the plasma membrane when expressed in tobacco. Its overexpression increased tobacco Cd-tolerance and resulted in enhanced cadmium concentration in leaf vacuoles, indicating more efficient detoxification by means of vacuolar storage. Heterologous AtMRP7 expression also led to more efficient retention of Cd in roots, suggesting a contribution to the control of cadmium root-to-shoot translocation. The results underscore the use of AtMRP7 in plant genetic engineering to modify the heavy-metal accumulation pattern for a broad range of applications. - AtMRP7 expression in tobacco enhances Cd-tolerance and increases Cd storage in vacuoles

  14. Jatropha curcas L. Root Structure and Growth in Diverse Soils

    OpenAIRE

    Ofelia Andrea Valdés-Rodríguez; Odilón Sánchez-Sánchez; Arturo Pérez-Vázquez; Caplan, Joshua S.; Frédéric Danjon

    2013-01-01

    Unlike most biofuel species, Jatropha curcas has promise for use in marginal lands, but it may serve an additional role by stabilizing soils. We evaluated the growth and structural responsiveness of young J. curcas plants to diverse soil conditions. Soils included a sand, a sandy-loam, and a clay-loam from eastern Mexico. Growth and structural parameters were analyzed for shoots and roots, although the focus was the plasticity of the primary root system architecture (the taproot and four late...

  15. Response of Arabidopsis thaliana Roots with Altered Lipid Transfer Protein (LTP) Gene Expression to the Clubroot Disease and Salt Stress

    OpenAIRE

    Sabine Jülke; Jutta Ludwig-Müller

    2015-01-01

    The clubroot disease of Brassicaceae is caused by the obligate biotrophic protist Plasmodiophora brassicae. The disease is characterized by abnormal tumorous swellings of infected roots that result in reduced drought resistance and insufficient distribution of nutrients, leading to reduced crop yield. It is one of the most damaging diseases among cruciferous crops worldwide. The acquisition of nutrients by the protist is not well understood. Gene expression profiles in Arabidopsis thaliana cl...

  16. RNAi-mediated gene silencing reveals involvement of Arabidopsis chromatin-related genes in Agrobacterium-mediated root transformation

    OpenAIRE

    Crane, Yan Ma; Gelvin, Stanton B

    2007-01-01

    We investigated the effect of RNAi-mediated gene silencing of 109 Arabidopsis thaliana chromatin-related genes (termed “chromatin genes” hereafter) on Agrobacterium-mediated root transformation. Each of the RNAi lines contains a single- or low-copy-number insertion of a hairpin construction that silences the endogenous copy of the target gene. We used three standard transient and stable transformation assays to screen 340 independent RNAi lines, representing 109 target genes, for the rat (res...

  17. Differences in photosynthesis and terpene content in leaves and roots of wild-type and transgenic Arabidopsis thaliana plants

    OpenAIRE

    Blanch Roure, Josep-Salvador; Peñuelas, Josep; Llusià Benet, Joan; Sardans i Galobart, Jordi; Owen, Susan M.

    2015-01-01

    We investigated the hypotheses that two different varieties of Arabidopsis thaliana show differences in physiology and terpene production. The two varieties of A. thaliana used in this study were wildtype (WT) and transgenic line (CoxIVFaNES I) genetically modified to emit nerolidol with linalool/nerolidol synthase (COX). Photosynthetic rate, electron transport rate, fluorescence, leaf volatile terpene contents and root volatile terpene contents were analyzed. For both types, we found coeluti...

  18. Winter Wheat Root Growth and Nitrogen Relations

    DEFF Research Database (Denmark)

    Rasmussen, Irene Skovby

    in winter wheat (Triticum aestivum L). Field experiments on the effect of sowing date, N fertilization and cultivars were conducted on a sandy loam soil in Taastrup, Denmark. The root studies were conducted by means of the minirhizotron method. Also, a field experiment on the effect of defoliation...

  19. Establishment of embryonic shoot–root axis is involved in auxin and cytokinin response during Arabidopsis somatic embryogenesis

    Directory of Open Access Journals (Sweden)

    Ying Hua eSu

    2015-01-01

    Full Text Available Auxin and cytokinin signaling participates in regulating a large spectrum of developmental and physiological processes in plants. The shoots and roots of plants have specific and sometimes even contrary responses to these hormones. Recent studies have clearly shown that establishing the spatiotemporal distribution of auxin and cytokinin response signals is central for the control of shoot apical meristem (SAM induction in cultured tissues. However, little is known about the role of these hormones in root apical meristem (RAM initiation. Here, we found that the expression patterns of several regulatory genes critical for RAM formation were correlated with the establishment of the embryonic root meristem during somatic embryogenesis in Arabidopsis. Interestingly, the early expression of the WUS-RELATED HOMEOBOX 5 (WOX5 and WUSCHEL (WUS genes was induced and was nearly overlapped within the embryonic callus when somatic embryos (SEs could not be identified morphologically. Their correct expression was essential for RAM and SAM initiation and embryonic shoot–root axis establishment. Furthermore, we analyzed the auxin and cytokinin response during SE initiation. Notably, cytokinin response signals were detected in specific regions that were correlated with induced WOX5 expression and subsequent SE formation. Overexpression of the ARABIDOPSIS RESPONSE REGULATOR genes ARR7 and ARR15 (feedback repressors of cytokinin signaling, disturbed RAM initiation and SE induction. These results provide new information on auxin and cytokinin-regulated apical–basal polarity formation of shoot–root axis during somatic embryogenesis.

  20. Arabidopsis ROOT HAIR DEFECTIVE3 is involved in nitrogen starvation-induced anthocyanin accumulation

    Institute of Scientific and Technical Information of China (English)

    Jing Wang; Yan Wang; Ju Yang; Chunli Ma; Ying Zhang; Ting Ge; Zhi Qi; Yan Kang

    2015-01-01

    Anthocyanin accumulation is a common phenom-enon seen in plants under environmental stress. In this study, we identified a new allele of ROOT HAIR DEFECTIVE3 (RHD3) showing an anthocyanin overaccumulation phenotype under nitrogen starvation conditions. It is known that ethylene negatively regulates light- and sucrose-induced anthocyanin biosynthesis. We hypothesized that RHD3 achieves its negative effect on anthocyanin biosynthesis via an ethylene-regulating pathway. In support of this, similar to rhd3 mutants, the Arabidopsis ethylene signaling mutants etr1, ein2, and ein3/eil1 showed an anthocyanin overaccumulation phenotype under nitrogen starvation conditions. The ethylene precursor ACC strongly suppressed anthocyanin accumulation, dependent on ETR1, EIN2, EIN3/EIL1, and, partially, RHD3. In addition, inactivating RHD3 partially reversed the suppressive effect of ETO1 inactivation-evoked endogenous ethylene production on anthocyanin accumulation. The expression of nitrogen starva-tion-induced anthocyanin biosynthesis genes was negatively regulated by RHD3, but ethylene response genes were positively regulated by RHD3. Wild-type seedlings overexpress-ing RHD3 showed similar phenotypes to rhd3 mutants, indicating the existence of a fine-tuned relationship between gene expression and function. RHD3 was initial y identified as a gene involved in root hair development. This study uncovered a new physiological function of RHD3 in nitrogen starvation-induced anthocyanin accumulation and ethylene homeostasis. Correction added on 6 August 2015, after first online publica-tion:“RND3”corrected to“RHD3”.

  1. Tracking transcription factor mobility and interaction in Arabidopsis roots with fluorescence correlation spectroscopy.

    Science.gov (United States)

    Clark, Natalie M; Hinde, Elizabeth; Winter, Cara M; Fisher, Adam P; Crosti, Giuseppe; Blilou, Ikram; Gratton, Enrico; Benfey, Philip N; Sozzani, Rosangela

    2016-01-01

    To understand complex regulatory processes in multicellular organisms, it is critical to be able to quantitatively analyze protein movement and protein-protein interactions in time and space. During Arabidopsis development, the intercellular movement of SHORTROOT (SHR) and subsequent interaction with its downstream target SCARECROW (SCR) control root patterning and cell fate specification. However, quantitative information about the spatio-temporal dynamics of SHR movement and SHR-SCR interaction is currently unavailable. Here, we quantify parameters including SHR mobility, oligomeric state, and association with SCR using a combination of Fluorescent Correlation Spectroscopy (FCS) techniques. We then incorporate these parameters into a mathematical model of SHR and SCR, which shows that SHR reaches a steady state in minutes, while SCR and the SHR-SCR complex reach a steady-state between 18 and 24 hr. Our model reveals the timing of SHR and SCR dynamics and allows us to understand how protein movement and protein-protein stoichiometry contribute to development. PMID:27288545

  2. Osmotic Effects on the Electrical Properties of Arabidopsis Root Hair Vacuoles in Situ1

    Science.gov (United States)

    Lew, Roger R.

    2004-01-01

    To assess the role of the vacuole in responses to hyperosmotic and hypo-osmotic stress, the electrical properties of the vacuole were measured in situ. A double-barrel micropipette was inserted into the vacuole for voltage clamping. A second double-barrel micropipette was inserted into the cytoplasm to provide a virtual ground that separated the electrical properties of the vacuole from those of the plasma membrane. Osmotic stress causes immediate electrical responses at the plasma membrane (Lew RR [1996] Plant Physiol 97: 2002-2005) and ion flux changes and turgor recovery (Shabala SN, Lew RR [2002] 129: 290-299) in Arabidopsis root cells. In situ, the vacuole also responds rapidly to changes in extracellular osmotic potential. Hyperosmotic treatment caused a very large increase in the ionic conductance of the vacuole. Hypo-osmotic treatment did not affect the vacuolar conductance. In either case, the vacuolar electrical potential was unchanged. Taken in concert with previous studies of changes at the plasma membrane, these results demonstrate a highly coordinated system in which the vacuole and plasma membrane are primed to respond immediately to hyperosmotic stress before changes in gene expression. PMID:14730070

  3. Tissue organization and cell ultrastructure in the roots of three Arabidopsis species grown at different zinc concentrations

    Directory of Open Access Journals (Sweden)

    M. Čiamporová

    2015-05-01

    Full Text Available The model plant Arabidopsis thaliana is known to be heavy metal-sensitive in contrast to its relative species A. arenosa and A. halleri classified as pseudometallophytes. Quantitative differences in primary root anatomy previously found between A. thaliana and the non-metallicolous (NM and metallicolous (M populations of the non-model Arabidopsis species necessitated further research at cellular and ultrastructural levels. Seedlings of A. thaliana, ecotype Columbia and a natural population Ratkovo, the NM and M populations of A. arenosa and A. halleri were grown on agar medium containing 10 μM (control and 1000 μM Zn2+ for 5 days. Light microscopy confirmed the higher number of cells in the endodermal, cortical and epidermal layers and a higher incidence of additional cell tiers, the so-called middle cortex (MC in the tolerant genotypes. Such differences were present in untreated plants and even more pronounced in plants exposed to excess of zinc (Zn. Electron microscopy of the root tissues at comparable distances from the root tip showed Casparian bands only in the radial cell walls of endodermis of A. halleri M population originating from severely (Cu, Cd and Pb contaminated site. Casparian bands were not differentiated yet in the roots of the other species and populations, and they were not formed in the cell walls between endodermis and MC cells. In the apical cytoplasm of trichoblast bulges, autophagic vacuoles were found only in the sensitive A. thaliana and small vacuoles in the other genotypes. The enhanced concentration of Zn confirmed the higher metal sensitivity of the model species and did not substantially disturb the root cell ultrastructure of the tolerant Arabidopsis species.

  4. The Arabidopsis Root Transcriptome by Serial Analysis of Gene Expression. Gene Identification Using the Genome Sequence1

    Science.gov (United States)

    Fizames, Cécile; Muños, Stéphane; Cazettes, Céline; Nacry, Philippe; Boucherez, Jossia; Gaymard, Frédéric; Piquemal, David; Delorme, Valérie; Commes, Thérèse; Doumas, Patrick; Cooke, Richard; Marti, Jacques; Sentenac, Hervé; Gojon, Alain

    2004-01-01

    Large-scale identification of genes expressed in roots of the model plant Arabidopsis was performed by serial analysis of gene expression (SAGE), on a total of 144,083 sequenced tags, representing at least 15,964 different mRNAs. For tag to gene assignment, we developed a computational approach based on 26,620 genes annotated from the complete sequence of the genome. The procedure selected warrants the identification of the genes corresponding to the majority of the tags found experimentally, with a high level of reliability, and provides a reference database for SAGE studies in Arabidopsis. This new resource allowed us to characterize the expression of more than 3,000 genes, for which there is no expressed sequence tag (EST) or cDNA in the databases. Moreover, 85% of the tags were specific for one gene. To illustrate this advantage of SAGE for functional genomics, we show that our data allow an unambiguous analysis of most of the individual genes belonging to 12 different ion transporter multigene families. These results indicate that, compared with EST-based tag to gene assignment, the use of the annotated genome sequence greatly improves gene identification in SAGE studies. However, more than 6,000 different tags remained with no gene match, suggesting that a significant proportion of transcripts present in the roots originate from yet unknown or wrongly annotated genes. The root transcriptome characterized in this study markedly differs from those obtained in other organs, and provides a unique resource for investigating the functional specificities of the root system. As an example of the use of SAGE for transcript profiling in Arabidopsis, we report here the identification of 270 genes differentially expressed between roots of plants grown either with NO3- or NH4NO3 as N source. PMID:14730065

  5. Field grown Acacia Mangium: how intensive is root growth?

    International Nuclear Information System (INIS)

    Under rainfed conditions, root development of trees can be very unpredictable and variable, depending on the amount and distribution of rainfall received. This becomes more critical when the rainfall is seasonal and the soil has a high clay content. Our investigation dealt with the root development of Acacia mangium established as plantation forest on a soil with heavy clay texture in Kemasul Forest Reserve, Malaysia. The distribution of active roots was measured at 9- and 21- month-old plantations using the radioactive P injection method. Growth at different distances from the tree base and at different soil depths was studied. After nine months of field planting, we found that roots were mostly concentrated at the surface within 1000 mm distance from the tree base. At one year after the first measurement, roots were traced as far as 6400 mm away. A large part of these roots, however, were detected within 3700 mm distance in the upper 300 mm soil. At this stage, roots can still did not go deeper than 450 mm depth, probably due to the high clay content at lower depth and low pH. This rapid root growth indicates that below-ground competition can be very intense if this species is established as a mixed-species plantation

  6. Root Growth Optimizer with Self-Similar Propagation

    Directory of Open Access Journals (Sweden)

    Xiaoxian He

    2015-01-01

    Full Text Available Most nature-inspired algorithms simulate intelligent behaviors of animals and insects that can move spontaneously and independently. The survival wisdom of plants, as another species of biology, has been neglected to some extent even though they have evolved for a longer period of time. This paper presents a new plant-inspired algorithm which is called root growth optimizer (RGO. RGO simulates the iterative growth behaviors of plant roots to optimize continuous space search. In growing process, main roots and lateral roots, classified by fitness values, implement different strategies. Main roots carry out exploitation tasks by self-similar propagation in relatively nutrient-rich areas, while lateral roots explore other places to seek for better chance. Inhibition mechanism of plant hormones is applied to main roots in case of explosive propagation in some local optimal areas. Once resources in a location are exhausted, roots would shrink away from infertile conditions to preserve their activity. In order to validate optimization effect of the algorithm, twelve benchmark functions, including eight classic functions and four CEC2005 test functions, are tested in the experiments. We compared RGO with other existing evolutionary algorithms including artificial bee colony, particle swarm optimizer, and differential evolution algorithm. The experimental results show that RGO outperforms other algorithms on most benchmark functions.

  7. Plant growth-promoting rhizobacteria and root system functioning

    Directory of Open Access Journals (Sweden)

    Jordan eVacheron

    2013-09-01

    Full Text Available The rhizosphere supports the development and activity of a huge and diversified microbial community, including microorganisms capable to promote plant growth. Among the latter, Plant Growth-Promoting Rhizobacteria (PGPR colonize roots of monocots and dicots, and enhance plant growth by direct and indirect mechanisms. Modification of root system architecture by PGPR implicates the production of phytohormones and other signals that lead, mostly, to enhanced lateral root branching and development of root hairs. PGPR also modify root functioning, improve plant nutrition and influence the physiology of the whole plant. Recent results provided first clues as to how PGPR signals could trigger these plant responses. Whether local and/or systemic, the plant molecular pathways involved remain often unknown. From an ecological point of view, it emerged that PGPR form coherent functional groups, whose rhizosphere ecology is influenced by a myriad of abiotic and biotic factors in natural and agricultural soils, and these factors can in turn modulate PGPR effects on roots. In this paper, we address novel knowledge and gaps on PGPR modes of action and signals, and highlight recent progress on the links between plant morphological and physiological effects induced by PGPR. We also show the importance of taking into account the size, diversity and gene expression patterns of PGPR assemblages in the rhizosphere to better understand their impact on plant growth and functioning. Integrating mechanistic and ecological knowledge on PGPR populations in soil will be a prerequisite to develop novel management strategies for sustainable agriculture.

  8. Synergistic growth effect among bacteria recovered from root canal infections

    Directory of Open Access Journals (Sweden)

    Gil Moreira Júnior

    2011-09-01

    Full Text Available The objective of this study was to determine the ecological relationships between bacterial species that colonize infected root canals. Root canal bacteria recovered from one patient with pulp canal necrosis were evaluated in vitro for synergistic and antagonistic activities determined by mono and co-culture growth kinetics and the production of bacteriocin-like substances using the double layer diffusion method. Peptostreptococcus prevotii triggered a significant increase of Fusobacterium nucleatum growth, while the former bacteria did not affect the growth of P. prevotii. The bacterial species did not produce antagonism activity against itself or against any of the other two species. Despite many studies have demonstrated the capability of root canal microorganisms to produce antagonistic substances, these in vitro experimental tests show the synergistic effect of P. prevotii on the growth of F. nucleatum.

  9. Different degree in proteasome malfunction has various effects on root growth possibly through preventing cell division and promoting autophagic vacuolization.

    Directory of Open Access Journals (Sweden)

    Xianyong Sheng

    Full Text Available The ubiquitin/proteasome pathway plays a vital role in plant development. But the effects of proteasome malfunction on root growth, and the mechanism underlying this involvement remains unclear. In the present study, the effects of proteasome inhibitors on Arabidopsis root growth were studied through the analysis of the root length, and meristem size and cell length in maturation zone using FM4-64, and cell-division potential using GFP fusion cyclin B, and accumulation of ubiquitinated proteins using immunofluorescence labeling, and autophagy activity using LysoTracker and MDC. The results indicated that lower concentration of proteasome inhibitors promoted root growth, whereas higher concentration of inhibitors had the opposite effects. The accumulation of cyclin B was linked to MG132-induced decline in meristem size, indicating that proteasome malfunction prevented cell division. Besides, MG132-induced accumulation of the ubiquitinated proteins was associated with the increasing fluorescence signal of LysoTracker and MDC in the elongation zone, revealing a link between the activation of autophagy and proteasome malfunction. These results suggest that weak proteasome malfunction activates moderate autophagy and promotes cell elongation, which compensates the inhibitor-induced reduction of cell division, resulting in long roots. Whereas strong proteasome malfunction induces severe autophagy and disturbs cell elongation, resulting in short roots.

  10. Constitutive expression of OsIAA9 affects starch granules accumulation and root gravitropic response in Arabidopsis

    Directory of Open Access Journals (Sweden)

    Sha eLuo

    2015-12-01

    Full Text Available Auxin/Indole-3-Acetic Acid (Aux/IAA genes are early auxin response genes ecoding short-lived transcriptional repressors, which regulate auxin signaling in plants by interplay with Auxin Response Factors (ARFs. Most of the Aux/IAA proteins contain four different domains, namely Domain I, Domain II, Domain III and Domain IV. So far all Aux/IAA mutants with auxin-related phenotypes identified in both Arabidopsis and rice (Oryza sativa are dominant gain-of-function mutants with mutations in Domain II of the corresponding Aux/IAA proteins, suggest that Aux/IAA proteins in both Arabidopsis and rice are largely functional redundantly, and they may have conserved functions. We report here the functional characterization of a rice Aux/IAA gene, OsIAA9. RT-PCR results showed that expression of OsIAA9 was induced by exogenously applied auxin, suggesting that OsIAA9 is an auxin response gene. Bioinformatic analysis showed that OsIAA9 has a repressor motif in Domain I, a degron in Domain II, and the conserved amino acid signatures for protein-protein interactions in Domain III and Domain IV. By generating transgenic plants expressing GFP-OsIAA9 and examining florescence in the transgenic plants, we found that OsIAA9 is localized in the nucleus. When transfected into protoplasts isolated from rosette leaves of Arabidopsis, OsIAA9 repressed reporter gene expression, and the repression was partially released by exogenously IAA. These results suggest that OsIAA9 is a canonical Aux/IAA protein. Protoplast transfection assays showed that OsIAA9 interacted ARF5, but not ARF6, 7, 8 and 19. Transgenic Arabidopsis plants expressing OsIAA9 have increased number of lateral roots, and reduced gravitropic response. Further analysis showed that OsIAA9 transgenic Arabidopsis plants accumulated fewer granules in their root tips and the distribution of granules was also affected. Taken together, our study showed that OsIAA9 is a transcriptional repressor, and it regulates

  11. Responses to Iron-Deficiency in Arabidopsis-Thaliana - The Turbo Iron Reductase does not depend on the Formation of Root Hairs and Transfer Cells.

    NARCIS (Netherlands)

    Moog, P.R.; Van der Kooij, T.A.W.; Bruggemann, W.; Schiefelbein, J.W.; Kuiper, P.J.C.

    1995-01-01

    Arabidopsis thaliana (L.) Heynh. Columbia wild type and a root hair-less mutant RM57 were grown on iron-containing and iron-deficient nutrient solutions. In both genotypes, ferric chelate reductase (FCR) of intact roots was induced upon iron deficiency and followed a Michaelis-Menten kinetic with a

  12. Impact of elevated CO2 on growth and development of Arabidopsis thaliana L

    NARCIS (Netherlands)

    van der Kooij, T.A W; De Kok, L.J.

    1996-01-01

    After germination, Arabidopsis thaliana L (cv. Landsberg) was grown at 350 mu l l(-1) (control) or 700 mu l l(-1) (elevated) CO2. Total shoot biomass at the end of the vegetative growth period was increased by 56% due to a short transient stimulation of the relative growth rate by elevated CO2 at th

  13. Quantitative trait local analysis of growth-related traits in a new Arabidopsis recombinant inbred population

    NARCIS (Netherlands)

    El-Lithy, M.E.M.; Clerkx, E.J.M.; Ruijs, G.J.; Koornneef, M.; Vreugdenhil, D.

    2004-01-01

    Arabidopsis natural variation was used to analyze the genetics of plant growth rate. Screening of 22 accessions revealed a large variation for seed weight, plant dry weight and relative growth rate but not for water content. A positive correlation was observed between seed weight and plant area 10 d

  14. Plasma membrane proteomics in the maize primary root growth zone: novel insights into root growth adaptation to water stress.

    Science.gov (United States)

    Voothuluru, Priyamvada; Anderson, Jeffrey C; Sharp, Robert E; Peck, Scott C

    2016-09-01

    Previous work on maize (Zea mays L.) primary root growth under water stress showed that cell elongation is maintained in the apical region of the growth zone but progressively inhibited further from the apex. These responses involve spatially differential and coordinated regulation of osmotic adjustment, modification of cell wall extensibility, and other cellular growth processes that are required for root growth under water-stressed conditions. As the interface between the cytoplasm and the apoplast (including the cell wall), the plasma membrane likely plays critical roles in these responses. Using a simplified method for enrichment of plasma membrane proteins, the developmental distribution of plasma membrane proteins was analysed in the growth zone of well-watered and water-stressed maize primary roots. The results identified 432 proteins with differential abundances in well-watered and water-stressed roots. The majority of changes involved region-specific patterns of response, and the identities of the water stress-responsive proteins suggest involvement in diverse biological processes including modification of sugar and nutrient transport, ion homeostasis, lipid metabolism, and cell wall composition. Integration of the distinct, region-specific plasma membrane protein abundance patterns with results from previous physiological, transcriptomic and cell wall proteomic studies reveals novel insights into root growth adaptation to water stress. PMID:27341663

  15. Tissue-specific root ion profiling reveals essential roles of the CAX and ACA calcium transport systems in response to hypoxia in Arabidopsis.

    Science.gov (United States)

    Wang, Feifei; Chen, Zhong-Hua; Liu, Xiaohui; Colmer, Timothy David; Zhou, Meixue; Shabala, Sergey

    2016-06-01

    Waterlogging is a major abiotic stress that limits the growth of plants. The crucial role of Ca(2+) as a second messenger in response to abiotic and biotic stimuli has been widely recognized in plants. However, the physiological and molecular mechanisms of Ca(2+) distribution within specific cell types in different root zones under hypoxia is poorly understood. In this work, whole-plant physiological and tissue-specific Ca(2+) changes were studied using several ACA (Ca(2+)-ATPase) and CAX (Ca(2+)/proton exchanger) knock-out Arabidopsis mutants subjected to waterlogging treatment. In the wild-type (WT) plants, several days of hypoxia decreased the expression of ACA8, CAX4, and CAX11 by 33% and 50% compared with the control. The hypoxic treatment also resulted in an up to 11-fold tissue-dependent increase in Ca(2+) accumulation in root tissues as revealed by confocal microscopy. The increase was much higher in stelar cells in the mature zone of Arabidopsis mutants with loss of function for ACA8, ACA11, CAX4, and CAX11 In addition, a significantly increased Ca(2+) concentration was found in the cytosol of stelar cells in the mature zone after hypoxic treatment. Three weeks of waterlogging resulted in dramatic loss of shoot biomass in cax11 plants (67% loss in shoot dry weight), while in the WT and other transport mutants this decline was only 14-22%. These results were also consistent with a decline in leaf chlorophyll fluorescence (F v/F m). It is suggested that CAX11 plays a key role in maintaining cytosolic Ca(2+) homeostasis and/or signalling in root cells under hypoxic conditions. PMID:26889007

  16. Hemoglobin is essential for normal growth of Arabidopsis organs

    DEFF Research Database (Denmark)

    Hebelstrup, Kim Henrik; Hunt, Peter; Dennis, Elizabeth; Jensen, Susie Bjerregaard; Jensen, Erik Østergaard

    2006-01-01

    In Arabidopsis thaliana, the class I hemoglobin AHb1 is transiently expressed in the hydathodes of leaves and in floral buds from young inflorescences. Nitric oxide (NO) accumulates to high levels in these organs when AHb1 is silenced, indicating an important role in metabolizing NO. AHb1-silenced...... lines are viable but show a mutant phenotype affecting the regions where AHb1 is expressed. Arabidopsis lines with an insertional knockout or overexpression of AHb2, a class II 3-on-3 hemoglobin, were generated. Seedlings overexpressing AHb2 show enhanced survival of hypoxic stress. The AHb2 knockout...... lines develop normally. However, when AHb2 knockout is combined with AHb1 silencing, seedlings die at an early vegetative stage suggesting that the two 3-on-3 hemoglobins, AHb1 and AHb2, together play an essential role for normal development of Arabidopsis seedlings. In conclusion, these results...

  17. Root-specific CLE19 overexpression and the sol1/2: Suppressors implicate a CLV-like pathway in the control of Arabidopsis root meristern maintenance

    OpenAIRE

    Casamitjana-Martinez, E.; Hofhuis, H.F.; Xu, J.; Liu, C. M.; Heidstra, R.; Scheres, B.J.G.

    2003-01-01

    In the Arabidopsis shoot apical meristem, an organizing center signals in a non-cell-autonomous manner to specify the overlying stem cells [1 and 2]. Stem cells express the small, secreted protein CLAVATA3 (CLV3; [3]) that activates the CLV1-CLV2 receptor complex, which negatively controls the size of the organizing center [4, 5 and 6]. Consistently, CLV3 overexpression restricts shoot meristem size [6]. The root meristem also contains a stem cell organizer, and here we show that localized ov...

  18. A root-specific wall-associated kinase gene, HvWAK1, regulates root growth and is highly divergent in barley and other cereals.

    Science.gov (United States)

    Kaur, Ravneet; Singh, Kashmir; Singh, Jaswinder

    2013-06-01

    Wall-associated receptor-like kinases (WAKs) are important candidates for directly linking the extracellular matrix with intracellular compartments and are involved in developmental processes and stress response. WAK gene family has been identified in plants such as Arabidopsis and rice. Here, we present a detailed analysis of the WAK1 gene from barley cv. Golden Promise, mapped to chromosome 5H. Three BAC clones corresponding to the WAK fragment were sequenced and the full-length WAK1 gene was characterized. The gene has three exons and two short introns with a coding region of 2,178 bp encoding a protein of 725 amino acids. A regulatory region was analyzed in -1,000 bp sequence upstream to start codon. Using conserved domains database and SMART, various conserved domains such as GUB WAK Bind, epidermal growth factor CA, and protein kinase C as well as other regions like signal peptides, active sites, and transmembrane domains were identified. The gene organization of HvWAK1 was compared with wheat (TaWAK1) and Arabidopsis (AtWAK1), suggesting that the WAK1 gene organization has remained highly conserved. Nonetheless, WAK1 was found to be highly divergent when compared with sequences available from barley cv. Haruna Nijo (50 %), rice (46 %), wheat (21 %), Arabidopsis (25 %), and maize (19 %). This divergence may have facilitated a better adaptation to surrounding environments due to its role in communication between the extracellular matrix, cell, and outer environment. Semiquantitative RT-PCR-based expression analysis indicates HvWAK1 expression is specific to roots. Significant differences in root growth between GP wild type and GP-Ds mutant seedlings were observed under control and salt stress conditions. PMID:23443578

  19. Insight into the early steps of root hair formation revealed by the procuste1 cellulose synthase mutant of Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Singh Manoj

    2008-05-01

    Full Text Available Abstract Background Formation of plant root hairs originating from epidermal cells involves selection of a polar initiation site and production of an initial hair bulge which requires local cell wall loosening. In Arabidopsis the polar initiation site is located towards the basal end of epidermal cells. However little is currently understood about the mechanism for the selection of the hair initiation site or the mechanism by which localised hair outgrowth is achieved. The Arabidopsis procuste1 (prc1-1 cellulose synthase mutant was studied in order to investigate the role of the cell wall loosening during the early stages of hair formation. Results The prc1-1 mutant exhibits uncontrolled, preferential bulging of trichoblast cells coupled with mislocalised hair positioning. Combining the prc1-1 mutant with root hair defective6-1 (rhd6-1, which on its own is almost completely devoid of root hairs results in a significant restoration of root hair formation. The pEXPANSIN7::GFP (pEXP7::GFP marker which is specifically expressed in trichoblast cell files of wild-type roots, is absent in the rhd6-1 mutant. However, pEXP7::GFP expression in the rhd6-1/prc1-1 double mutant is restored in a subset of epidermal cells which have either formed a root hair or exhibit a bulged phenotype consistent with a function for EXP7 during the early stages of hair formation. Conclusion These results show that RHD6 acts upstream of the normal cell wall loosening event which involves EXP7 expression and that in the absence of a functional RHD6 the loosening and accompanying EXP7 expression is blocked. In the prc1-1 mutant background, the requirement for RHD6 during hair initiation is reduced which may result from a weaker cell wall structure mimicking the cell wall loosening events during hair formation.

  20. Key divisions in the early Arabidopsis embryo require POL and PLL1 phosphatases to establish the root stem organizer and vascular axis

    OpenAIRE

    Song, Sang-Kee; Hofhuis, Hugo; Lee, Myeong Min; Clark, Steven E

    2008-01-01

    Arabidopsis development proceeds from three stem cell populations located at the shoot, flower and root meristems. The relationship between the highly related shoot and flower stem cells with the very divergent root stem cells has been unclear. We show that the related phosphatases POL and PLL1 are required for all three stem cell populations. pol pll1 mutant embryos lack key asymmetric divisions that give rise to the root stem cell organizer and the central vascular axis. Instead, these cell...

  1. Cell patterns emerge from coupled chemical and physical fields with cell proliferation dynamics: the Arabidopsis thaliana root as a study system.

    Directory of Open Access Journals (Sweden)

    Rafael A Barrio

    Full Text Available A central issue in developmental biology is to uncover the mechanisms by which stem cells maintain their capacity to regenerate, yet at the same time produce daughter cells that differentiate and attain their ultimate fate as a functional part of a tissue or an organ. In this paper we propose that, during development, cells within growing organs obtain positional information from a macroscopic physical field that is produced in space while cells are proliferating. This dynamical interaction triggers and responds to chemical and genetic processes that are specific to each biological system. We chose the root apical meristem of Arabidopsis thaliana to develop our dynamical model because this system is well studied at the molecular, genetic and cellular levels and has the key traits of multicellular stem-cell niches. We built a dynamical model that couples fundamental molecular mechanisms of the cell cycle to a tension physical field and to auxin dynamics, both of which are known to play a role in root development. We perform extensive numerical calculations that allow for quantitative comparison with experimental measurements that consider the cellular patterns at the root tip. Our model recovers, as an emergent pattern, the transition from proliferative to transition and elongation domains, characteristic of stem-cell niches in multicellular organisms. In addition, we successfully predict altered cellular patterns that are expected under various applied auxin treatments or modified physical growth conditions. Our modeling platform may be extended to explicitly consider gene regulatory networks or to treat other developmental systems.

  2. Development of test method for evaluating root resistance of pavement used for roof garden caused by thickening growth of root

    Energy Technology Data Exchange (ETDEWEB)

    Ishihara, Saori; Tanaka, Kyoji [Tokyo Institute of Technology, Tokyo, (Japan)

    2010-07-01

    The growth of roots of plants can damage roof garden components, such as pavements. This paper developed a test method for evaluating the resistance of pavement used in roof gardens to damage from a thickening growth of roots. The study assessed the behaviour of plant roots and evaluated the force of root growth subjected to hypertrophy. A system to measure the enlargement force of roots was designed and used for measurements over a period of 8 months on a cherry blossom of 21 years growth. The enlargement force was approximately 440 N/cm. A mechanical simulated root was designed and used to carry out experimental tests on asphalt pavements. The tests results demonstrated the viability of simulated root for evaluation of root resistances in pavements and various components of roof gardens.

  3. AINTEGUMENTA and the D-type cyclin CYCD3;1 regulate root secondary growth and respond to cytokinins.

    Science.gov (United States)

    Randall, Ricardo S; Miyashima, Shunsuke; Blomster, Tiina; Zhang, Jing; Elo, Annakaisa; Karlberg, Anna; Immanen, Juha; Nieminen, Kaisa; Lee, Ji-Young; Kakimoto, Tatsuo; Blajecka, Karolina; Melnyk, Charles W; Alcasabas, Annette; Forzani, Celine; Matsumoto-Kitano, Miho; Mähönen, Ari Pekka; Bhalerao, Rishikesh; Dewitte, Walter; Helariutta, Ykä; Murray, James A H

    2015-01-01

    Higher plant vasculature is characterized by two distinct developmental phases. Initially, a well-defined radial primary pattern is established. In eudicots, this is followed by secondary growth, which involves development of the cambium and is required for efficient water and nutrient transport and wood formation. Regulation of secondary growth involves several phytohormones, and cytokinins have been implicated as key players, particularly in the activation of cell proliferation, but the molecular mechanisms mediating this hormonal control remain unknown. Here we show that the genes encoding the transcription factor AINTEGUMENTA (ANT) and the D-type cyclin CYCD3;1 are expressed in the vascular cambium of Arabidopsis roots, respond to cytokinins and are both required for proper root secondary thickening. Cytokinin regulation of ANT and CYCD3 also occurs during secondary thickening of poplar stems, suggesting this represents a conserved regulatory mechanism. PMID:26340943

  4. AINTEGUMENTA and the D-type cyclin CYCD3;1 regulate root secondary growth and respond to cytokinins

    Directory of Open Access Journals (Sweden)

    Ricardo S. Randall

    2015-10-01

    Full Text Available Higher plant vasculature is characterized by two distinct developmental phases. Initially, a well-defined radial primary pattern is established. In eudicots, this is followed by secondary growth, which involves development of the cambium and is required for efficient water and nutrient transport and wood formation. Regulation of secondary growth involves several phytohormones, and cytokinins have been implicated as key players, particularly in the activation of cell proliferation, but the molecular mechanisms mediating this hormonal control remain unknown. Here we show that the genes encoding the transcription factor AINTEGUMENTA (ANT and the D-type cyclin CYCD3;1 are expressed in the vascular cambium of Arabidopsis roots, respond to cytokinins and are both required for proper root secondary thickening. Cytokinin regulation of ANT and CYCD3 also occurs during secondary thickening of poplar stems, suggesting this represents a conserved regulatory mechanism.

  5. Gravitropism in Arabidopsis thaliana: Root-specific action of the EHB gene and violation of the resultant law.

    Science.gov (United States)

    Dümmer, Michaela; Forreiter, Christoph; Galland, Paul

    2015-09-15

    Gravitropic bending of seedlings of Arabidopsis thaliana in response to centrifugal accelerations was determined in a range between 0.0025 and 4×g to revisit and validate the so-called resultant law, which claims that centrifugation causes gravitropic organs to orient parallel to the resultant stimulus vector. We show here for seedlings of A. thaliana that this empirical law holds for hypocotyls but surprisingly fails for roots. While the behavior of hypocotyls could be modeled by an arc tangent function predicted by the resultant law, roots displayed a sharp maximum at 1.8×g that substantially overshoots the predicted value and that represents a novel phenomenon, diagravitropism elicited by centrifugal acceleration. The gravitropic bending critically depended on the orientation of the seedling relative to the centrifugal acceleration. If the centrifugal vector pointed toward the cotyledons, gravitropic bending of hypocotyls and roots was substantially enhanced. The complex behavior of Arabidopsis seedlings provides strong evidence that gravitropic bending entails a cosine component (longitudinal stimulus) to which the seedlings were more sensitive than to the classical sine component. The absolute gravitropic thresholds of hypocotyls and roots were determined in a clinostat-centrifuge and found to be below 0.015×g. A tropism mutant lacking the EHB1 protein, which interacts with ARF-GAP (ARF GTPase-activating protein) and thus indirectly with a small ARF-type G protein, displayed a lower gravitropic threshold for roots and also enhanced bending, while the responses of the hypocotyls remained nearly unaffected. PMID:26496692

  6. Cinnamic acid increases lignin production and inhibits soybean root growth.

    Directory of Open Access Journals (Sweden)

    Victor Hugo Salvador

    Full Text Available Cinnamic acid is a known allelochemical that affects seed germination and plant root growth and therefore influences several metabolic processes. In the present work, we evaluated its effects on growth, indole-3-acetic acid (IAA oxidase and cinnamate 4-hydroxylase (C4H activities and lignin monomer composition in soybean (Glycine max roots. The results revealed that exogenously applied cinnamic acid inhibited root growth and increased IAA oxidase and C4H activities. The allelochemical increased the total lignin content, thus altering the sum and ratios of the p-hydroxyphenyl (H, guaiacyl (G, and syringyl (S lignin monomers. When applied alone or with cinnamic acid, piperonylic acid (PIP, a quasi-irreversible inhibitor of C4H reduced C4H activity, lignin and the H, G, S monomer content compared to the cinnamic acid treatment. Taken together, these results indicate that exogenously applied cinnamic acid can be channeled into the phenylpropanoid pathway via the C4H reaction, resulting in an increase in H lignin. In conjunction with enhanced IAA oxidase activity, these metabolic responses lead to the stiffening of the cell wall and are followed by a reduction in soybean root growth.

  7. YUCCA-mediated auxin biogenesis is required for cell fate transition occurring during de novo root organogenesis in Arabidopsis.

    Science.gov (United States)

    Chen, Lyuqin; Tong, Jianhua; Xiao, Langtao; Ruan, Ying; Liu, Jingchun; Zeng, Minhuan; Huang, Hai; Wang, Jia-Wei; Xu, Lin

    2016-07-01

    Many plant organs have the ability to regenerate a new plant after detachment or wounding via de novo organogenesis. During de novo root organogenesis from Arabidopsis thaliana leaf explants, endogenic auxin is essential for the fate transition of regeneration-competent cells to become root founder cells via activation of WUSCHEL-RELATED HOMEOBOX 11 (WOX11). However, the molecular events from leaf explant detachment to auxin-mediated cell fate transition are poorly understood. In this study, we used an assay to determine the concentration of indole-3-acetic acid (IAA) to provide direct evidence that auxin is produced after leaf explant detachment, a process that involves YUCCA (YUC)-mediated auxin biogenesis. Inhibition of YUC prevents expression of WOX11 and fate transition of competent cells, resulting in the blocking of rooting. Further analysis showed that YUC1 and YUC4 act quickly (within 4 hours) in response to wounding after detachment in both light and dark conditions and promote auxin biogenesis in both mesophyll and competent cells, whereas YUC5, YUC8, and YUC9 primarily respond in dark conditions. In addition, YUC2 and YUC6 contribute to rooting by providing a basal auxin level in the leaf. Overall, our study indicates that YUC genes exhibit a division of labour during de novo root organogenesis from leaf explants in response to multiple signals. PMID:27255928

  8. Roles of Proteome Dynamics and Cytokinin Signaling in Root to Hypocotyl Ratio Changes Induced by Shading Roots of Arabidopsis Seedlings

    Czech Academy of Sciences Publication Activity Database

    Novak, J.; Černý, M.; Pavlů, J.; Zemánková, J.; Skalák, J.; Plačková, Lenka; Brzobohatý, Břetislav

    2015-01-01

    Roč. 56, č. 5 (2015), s. 1006-1018. ISSN 0032-0781 R&D Projects: GA MŠk(CZ) LO1204 Grant ostatní: GA ČR(CZ) GAP305/12/2144 Institutional support: RVO:68081707 ; RVO:61389030 Keywords : Arabidopsis thaliana * Cytokinin * Hypocotyl elongation Subject RIV: BO - Biophysics; EF - Botanics (UEB-Q) Impact factor: 4.931, year: 2014

  9. Phytotoxicity of nanoparticles: Inhibition of seed germination and root growth

    International Nuclear Information System (INIS)

    Plants need to be included to develop a comprehensive toxicity profile for nanoparticles. Effects of five types of nanoparticles (multi-walled carbon nanotube, aluminum, alumina, zinc, and zinc oxide) on seed germination and root growth of six higher plant species (radish, rape, ryegrass, lettuce, corn, and cucumber) were investigated. Seed germination was not affected except for the inhibition of nanoscale zinc (nano-Zn) on ryegrass and zinc oxide (nano-ZnO) on corn at 2000 mg/L. Inhibition on root growth varied greatly among nanoparticles and plants. Suspensions of 2000 mg/L nano-Zn or nano-ZnO practically terminated root elongation of the tested plant species. Fifty percent inhibitory concentrations (IC50) of nano-Zn and nano-ZnO were estimated to be near 50 mg/L for radish, and about 20 mg/L for rape and ryegrass. The inhibition occurred during the seed incubation process rather than seed soaking stage. These results are significant in terms of use and disposal of engineered nanoparticles. - Engineered nanoparticles can inhibit the seed germination and root growth

  10. Phytotoxicity of nanoparticles: Inhibition of seed germination and root growth

    Energy Technology Data Exchange (ETDEWEB)

    Lin Daohui [Department of Environmental Science, Zhejiang University, Hangzhou 310028 (China); Department of Plant, Soil and Insect Sciences, University of Massachusetts, Stockbridge Hall, Amherst, MA 01003 (United States); Xing Baoshan [Department of Plant, Soil and Insect Sciences, University of Massachusetts, Stockbridge Hall, Amherst, MA 01003 (United States)], E-mail: bx@pssci.umass.edu

    2007-11-15

    Plants need to be included to develop a comprehensive toxicity profile for nanoparticles. Effects of five types of nanoparticles (multi-walled carbon nanotube, aluminum, alumina, zinc, and zinc oxide) on seed germination and root growth of six higher plant species (radish, rape, ryegrass, lettuce, corn, and cucumber) were investigated. Seed germination was not affected except for the inhibition of nanoscale zinc (nano-Zn) on ryegrass and zinc oxide (nano-ZnO) on corn at 2000 mg/L. Inhibition on root growth varied greatly among nanoparticles and plants. Suspensions of 2000 mg/L nano-Zn or nano-ZnO practically terminated root elongation of the tested plant species. Fifty percent inhibitory concentrations (IC{sub 50}) of nano-Zn and nano-ZnO were estimated to be near 50 mg/L for radish, and about 20 mg/L for rape and ryegrass. The inhibition occurred during the seed incubation process rather than seed soaking stage. These results are significant in terms of use and disposal of engineered nanoparticles. - Engineered nanoparticles can inhibit the seed germination and root growth.

  11. A mutual support mechanism through intercellular movement of CAPRICE and GLABRA3 can pattern the Arabidopsis root epidermis.

    Directory of Open Access Journals (Sweden)

    Natasha Saint Savage

    2008-09-01

    Full Text Available The patterning of the Arabidopsis root epidermis depends on a genetic regulatory network that operates both within and between cells. Genetic studies have identified a number of key components of this network, but a clear picture of the functional logic of the network is lacking. Here, we integrate existing genetic and biochemical data in a mathematical model that allows us to explore both the sufficiency of known network interactions and the extent to which additional assumptions about the model can account for wild-type and mutant data. Our model shows that an existing hypothesis concerning the autoregulation of WEREWOLF does not account fully for the expression patterns of components of the network. We confirm the lack of WEREWOLF autoregulation experimentally in transgenic plants. Rather, our modelling suggests that patterning depends on the movement of the CAPRICE and GLABRA3 transcriptional regulators between epidermal cells. Our combined modelling and experimental studies show that WEREWOLF autoregulation does not contribute to the initial patterning of epidermal cell fates in the Arabidopsis seedling root. In contrast to a patterning mechanism relying on local activation, we propose a mechanism based on lateral inhibition with feedback. The active intercellular movements of proteins that are central to our model underlie a mechanism for pattern formation in planar groups of cells that is centred on the mutual support of two cell fates rather than on local activation and lateral inhibition.

  12. Quantitative Proteomic Analysis of the Response to Zinc, Magnesium, and Calcium Deficiency in Specific Cell Types of Arabidopsis Roots

    Directory of Open Access Journals (Sweden)

    Yoichiro Fukao

    2016-01-01

    Full Text Available The proteome profiles of specific cell types have recently been investigated using techniques such as fluorescence activated cell sorting and laser capture microdissection. However, quantitative proteomic analysis of specific cell types has not yet been performed. In this study, to investigate the response of the proteome to zinc, magnesium, and calcium deficiency in specific cell types of Arabidopsis thaliana roots, we performed isobaric tags for relative and absolute quantification (iTRAQ-based quantitative proteomics using GFP-expressing protoplasts collected by fluorescence-activated cell sorting. Protoplasts were collected from the pGL2-GFPer and pMGP-GFPer marker lines for epidermis or inner cell lines (pericycle, endodermis, and cortex, respectively. To increase the number of proteins identified, iTRAQ-labeled peptides were separated into 24 fractions by OFFGFEL electrophoresis prior to high-performance liquid chromatography coupled with mass spectrometry analysis. Overall, 1039 and 737 proteins were identified and quantified in the epidermal and inner cell lines, respectively. Interestingly, the expression of many proteins was decreased in the epidermis by mineral deficiency, although a weaker effect was observed in inner cell lines such as the pericycle, endodermis, and cortex. Here, we report for the first time the quantitative proteomics of specific cell types in Arabidopsis roots.

  13. AtNIGT1/HRS1 integrates nitrate and phosphate signals at the Arabidopsis root tip

    Science.gov (United States)

    Medici, Anna; Marshall-Colon, Amy; Ronzier, Elsa; Szponarski, Wojciech; Wang, Rongchen; Gojon, Alain; Crawford, Nigel M; Ruffel, Sandrine; Coruzzi, Gloria M; Krouk, Gabriel

    2015-01-01

    Nitrogen and phosphorus are among the most widely used fertilizers worldwide. Nitrate (NO3−) and phosphate (PO43−) are also signaling molecules whose respective transduction pathways are being intensively studied. However, plants are continuously challenged with combined nutritional deficiencies, yet very little is known about how these signaling pathways are integrated. Here we report the identification of a highly NO3−-inducible NRT1.1-controlled GARP transcription factor, HRS1, document its genome-wide transcriptional targets, and validate its cis-regulatory-elements. We demonstrate that this transcription factor and a close homolog repress primary root growth in response to P deficiency conditions, but only when NO3− is present. This system defines a molecular logic gate integrating P and N signals. We propose that NO3− and P signaling converge via double transcriptional and post-transcriptional control of the same protein, HRS1 PMID:25723764

  14. Modulation of root branching by a coumarin derivative

    OpenAIRE

    Li, Xiang; Gao, Ming-Jun

    2011-01-01

    A healthy root system is crucial to plant growth and survival. To maintain efficiency of root function, plants have to dynamically modulate root system architecture through various adaptive mechanisms such as lateral root formation to respond to a changing and diversified soil environment. Exogenous application of a coumarin derivative, 4-methylumbelliferone (4-MU), in Arabidopsis thaliana inhibits seed germination by mainly reducing primary root growth. UDP-glycosyltransferases play an integ...

  15. Transcriptional profile of maize roots under acid soil growth

    Directory of Open Access Journals (Sweden)

    Mattiello Lucia

    2010-09-01

    Full Text Available Abstract Background Aluminum (Al toxicity is one of the most important yield-limiting factors of many crops worldwide. The primary symptom of Al toxicity syndrome is the inhibition of root growth leading to poor water and nutrient absorption. Al tolerance has been extensively studied using hydroponic experiments. However, unlike soil conditions, this method does not address all of the components that are necessary for proper root growth and development. In the present study, we grew two maize genotypes with contrasting tolerance to Al in soil containing toxic levels of Al and then compared their transcriptomic responses. Results When grown in acid soil containing toxic levels of Al, the Al-sensitive genotype (S1587-17 showed greater root growth inhibition, more Al accumulation and more callose deposition in root tips than did the tolerant genotype (Cat100-6. Transcriptome profiling showed a higher number of genes differentially expressed in S1587-17 grown in acid soil, probably due to secondary effects of Al toxicity. Genes involved in the biosynthesis of organic acids, which are frequently associated with an Al tolerance response, were not differentially regulated in both genotypes after acid soil exposure. However, genes related to the biosynthesis of auxin, ethylene and lignin were up-regulated in the Al-sensitive genotype, indicating that these pathways might be associated with root growth inhibition. By comparing the two maize lines, we were able to discover genes up-regulated only in the Al-tolerant line that also presented higher absolute levels than those observed in the Al-sensitive line. These genes encoded a lipase hydrolase, a retinol dehydrogenase, a glycine-rich protein, a member of the WRKY transcriptional family and two unknown proteins. Conclusions This work provides the first characterization of the physiological and transcriptional responses of maize roots when grown in acid soil containing toxic levels of Al. The

  16. Disruption of ATCSLD5 results in reduced growth, reduced xylan and homogalacturonan synthase activity and altered xylan occurrence in Arabidopsis

    DEFF Research Database (Denmark)

    Bernal Giraldo, Adriana Jimena; Jensen, Jacob Krüger; Harholt, Jesper;

    2007-01-01

    Members of a large family of cellulose synthase-like genes (CSLs) are predicted to encode glycosyl transferases (GTs) involved in the biosynthesis of plant cell walls. The CSLA and CSLF families are known to contain mannan and glucan synthases, respectively, but the products of other CSLs are...... unknown. Here we report the effects of disrupting ATCSLD5 expression in Arabidopsis. Both stem and root growth were significantly reduced in ATCSLD5 knock-out plants, and these plants also had increased susceptibility to the cellulose synthase inhibitor isoxaben. Antibody and carbohydrate-binding module......, and the possible role(s) of this gene and other ATCSLDs in cell wall biosynthesis are discussed....

  17. Impact of root growth and root hydraulic conductance on water availability of young walnut trees

    Science.gov (United States)

    Jerszurki, Daniela; Couvreur, Valentin; Hopmans, Jan W.; Silva, Lucas C. R.; Shackel, Kenneth A.; de Souza, Jorge L. M.

    2015-04-01

    Walnut (Juglans regia L.) is a tree species of high economic importance in the Central Valley of California. This crop has particularly high water requirements, which makes it highly dependent on irrigation. The context of decreasing water availability in the state calls for efficient water management practices, which requires improving our understanding of the relationship between water application and walnut water availability. In addition to the soil's hydraulic conductivity, two plant properties are thought to control the supply of water from the bulk soil to the canopy: (i) root distribution and (ii) plant hydraulic conductance. Even though these properties are clearly linked to crop water requirements, their quantitative relation remains unclear. The aim of this study is to quantitatively explain walnut water requirements under water deficit from continuous measurements of its water consumption, soil and stem water potential, root growth and root system hydraulic conductance. For that purpose, a greenhouse experiment was conducted for a two month period. Young walnut trees were planted in transparent cylindrical pots, equipped with: (i) rhizotron tubes, which allowed for non-invasive monitoring of root growth, (ii) pressure transducer tensiometers for soil water potential, (iii) psychrometers attached to non-transpiring leaves for stem water potential, and (iv) weighing scales for plant transpiration. Treatments consisted of different irrigation rates: 100%, 75% and 50% of potential crop evapotranspiration. Plant responses were compared to predictions from three simple process-based soil-plant-atmosphere models of water flow: (i) a hydraulic model of stomatal regulation based on stem water potential and vapor pressure deficit, (ii) a model of plant hydraulics predicting stem water potential from soil-root interfaces water potential, and (iii) a model of soil water depletion predicting the water potential drop between the bulk soil and soil-root interfaces

  18. A Journey Through a Leaf: Phenomics Analysis of Leaf Growth in Arabidopsis thaliana

    Science.gov (United States)

    Vanhaeren, Hannes; Gonzalez, Nathalie; Inzé, Dirk

    2015-01-01

    In Arabidopsis, leaves contribute to the largest part of the aboveground biomass. In these organs, light is captured and converted into chemical energy, which plants use to grow and complete their life cycle. Leaves emerge as a small pool of cells at the vegetative shoot apical meristem and develop into planar, complex organs through different interconnected cellular events. Over the last decade, numerous phenotyping techniques have been developed to visualize and quantify leaf size and growth, leading to the identification of numerous genes that contribute to the final size of leaves. In this review, we will start at the Arabidopsis rosette level and gradually zoom in from a macroscopic view on leaf growth to a microscopic and molecular view. Along this journey, we describe different techniques that have been key to identify important events during leaf development and discuss approaches that will further help unraveling the complex cellular and molecular mechanisms that underlie leaf growth. PMID:26217168

  19. CEP5 and XIP1/CEPR1 regulate lateral root initiation in Arabidopsis.

    Science.gov (United States)

    Roberts, Ianto; Smith, Stephanie; Stes, Elisabeth; De Rybel, Bert; Staes, An; van de Cotte, Brigitte; Njo, Maria Fransiska; Dedeyne, Lise; Demol, Hans; Lavenus, Julien; Audenaert, Dominique; Gevaert, Kris; Beeckman, Tom; De Smet, Ive

    2016-08-01

    Roots explore the soil for water and nutrients through the continuous production of lateral roots. Lateral roots are formed at regular distances in a steadily elongating organ, but how future sites for lateral root formation become established is not yet understood. Here, we identified C-TERMINALLY ENCODED PEPTIDE 5 (CEP5) as a novel, auxin-repressed and phloem pole-expressed signal assisting in the formation of lateral roots. In addition, based on genetic and expression data, we found evidence for the involvement of its proposed receptor, XYLEM INTERMIXED WITH PHLOEM 1 (XIP1)/CEP RECEPTOR 1 (CEPR1), during the process of lateral root initiation. In conclusion, we report here on the existence of a peptide ligand-receptor kinase interaction that impacts lateral root initiation. Our results represent an important step towards the understanding of the cellular communication implicated in the early phases of lateral root formation. PMID:27296247

  20. Cytokinin-Deficient Transgenic Arabidopsis Plants Show Multiple Developmental Alterations Indicating Opposite Functions of Cytokinins in the Regulation of Shoot and Root Meristem Activity

    Czech Academy of Sciences Publication Activity Database

    Werner, T.; Motyka, Václav; Laucou, V.; Smets, R.; Onckelen, H. V.; Schmülling, T.

    2003-01-01

    Roč. 15, č. 11 (2003), s. 2532-2550. ISSN 1040-4651 R&D Projects: GA AV ČR IAA6038002 Institutional research plan: CEZ:AV0Z5038910 Keywords : Transgenic Arabidopsis Plants * Cytokinins * Root Meristem Activity Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 10.679, year: 2003

  1. Colonization of the Arabidopsis rhizosphere by fluorescent Pseudomonas spp. activates a root-specific, ethylene-responsive PR-5 gene in the vascular bundle

    NARCIS (Netherlands)

    Léon-Kloosterziel, K.M.; Verhagen, B.W.M.; Keurentjes, J.J.B.; Pelt, J.A. van; Rep, M.; Loon, L.C. van; Pieterse, C.M.J.

    2005-01-01

    Plants of which the roots are colonized by selected strains of non-pathogenic, fluorescent Pseudomonas spp. develop an enhanced defensive capacity against a broad spectrum of foliar pathogens. In Arabidopsis thaliana, this rhizobacteria-induced systemic resistance (ISR) functions independently of sa

  2. A root chicory MADS box sequence and the Arabidopsis flowering repressor FLC share common features that suggest conserved function in vernalization and de-vernalization responses.

    Science.gov (United States)

    Périlleux, Claire; Pieltain, Alexandra; Jacquemin, Guillaume; Bouché, Frédéric; Detry, Nathalie; D'Aloia, Maria; Thiry, Laura; Aljochim, Pierre; Delansnay, Martin; Mathieu, Anne-Sophie; Lutts, Stanley; Tocquin, Pierre

    2013-08-01

    Root chicory (Cichorium intybus var. sativum) is a biennial crop, but is harvested to obtain root inulin at the end of the first growing season before flowering. However, cold temperatures may vernalize seeds or plantlets, leading to incidental early flowering, and hence understanding the molecular basis of vernalization is important. A MADS box sequence was isolated by RT-PCR and named FLC-LIKE1 (CiFL1) because of its phylogenetic positioning within the same clade as the floral repressor Arabidopsis FLOWERING LOCUS C (AtFLC). Moreover, over-expression of CiFL1 in Arabidopsis caused late flowering and prevented up-regulation of the AtFLC target FLOWERING LOCUS T by photoperiod, suggesting functional conservation between root chicory and Arabidopsis. Like AtFLC in Arabidopsis, CiFL1 was repressed during vernalization of seeds or plantlets of chicory, but repression of CiFL1 was unstable when the post-vernalization temperature was favorable to flowering and when it de-vernalized the plants. This instability of CiFL1 repression may be linked to the bienniality of root chicory compared with the annual lifecycle of Arabidopsis. However, re-activation of AtFLC was also observed in Arabidopsis when a high temperature treatment was used straight after seed vernalization, eliminating the promotive effect of cold on flowering. Cold-induced down-regulation of a MADS box floral repressor and its re-activation by high temperature thus appear to be conserved features of the vernalization and de-vernalization responses in distant species. PMID:23581257

  3. Tracking transcription factor mobility and interaction in arabidopsis roots with fluorescence correlation spectroscopy

    NARCIS (Netherlands)

    Clark, Natalie M.; Hinde, Elizabeth; Hinde, Elizabeth; Fisher, Adam P.; Crosti, Giuseppe; Blilou, Ikram; Gratton, Enrico; Benfey, Philip N.; Sozzani, Rosangela

    2016-01-01

    To understand complex regulatory processes in multicellular organisms, it is critical to be able to quantitatively analyze protein movement and protein-protein interactions in time and space. During Arabidopsis development, the intercellular movement of SHORTROOT (SHR) and subsequent interaction

  4. Response of Arabidopsis thaliana Roots with Altered Lipid Transfer Protein (LTP) Gene Expression to the Clubroot Disease and Salt Stress.

    Science.gov (United States)

    Jülke, Sabine; Ludwig-Müller, Jutta

    2015-01-01

    The clubroot disease of Brassicaceae is caused by the obligate biotrophic protist Plasmodiophora brassicae. The disease is characterized by abnormal tumorous swellings of infected roots that result in reduced drought resistance and insufficient distribution of nutrients, leading to reduced crop yield. It is one of the most damaging diseases among cruciferous crops worldwide. The acquisition of nutrients by the protist is not well understood. Gene expression profiles in Arabidopsis thaliana clubroots indicate that lipid transfer proteins (LTPs) could be involved in disease development or at least in adaptation to the disease symptoms. Therefore, the aim of the study was to examine the role of some, of the still enigmatic LTPs during clubroot development. For a functional approach, we have generated transgenic plants that overexpress LTP genes in a root specific manner or show reduced LTP gene expression. Our results showed that overexpression of some of the LTP genes resulted in reduced disease severity whereas the lipid content in clubs of LTP mutants seems to be unaffected. Additional studies indicate a role for some LTPs during salt stress conditions in roots of A. thaliana. PMID:27135222

  5. Response of Arabidopsis thaliana Roots with Altered Lipid Transfer Protein (LTP Gene Expression to the Clubroot Disease and Salt Stress

    Directory of Open Access Journals (Sweden)

    Sabine Jülke

    2015-12-01

    Full Text Available The clubroot disease of Brassicaceae is caused by the obligate biotrophic protist Plasmodiophora brassicae. The disease is characterized by abnormal tumorous swellings of infected roots that result in reduced drought resistance and insufficient distribution of nutrients, leading to reduced crop yield. It is one of the most damaging diseases among cruciferous crops worldwide. The acquisition of nutrients by the protist is not well understood. Gene expression profiles in Arabidopsis thaliana clubroots indicate that lipid transfer proteins (LTPs could be involved in disease development or at least in adaptation to the disease symptoms. Therefore, the aim of the study was to examine the role of some, of the still enigmatic LTPs during clubroot development. For a functional approach, we have generated transgenic plants that overexpress LTP genes in a root specific manner or show reduced LTP gene expression. Our results showed that overexpression of some of the LTP genes resulted in reduced disease severity whereas the lipid content in clubs of LTP mutants seems to be unaffected. Additional studies indicate a role for some LTPs during salt stress conditions in roots of A. thaliana.

  6. Growth enhancement and gene expression of Arabidopsis thaliana irradiated with active oxygen species

    Science.gov (United States)

    Watanabe, Satoshi; Ono, Reoto; Hayashi, Nobuya; Shiratani, Masaharu; Tashiro, Kosuke; Kuhara, Satoru; Inoue, Asami; Yasuda, Kaori; Hagiwara, Hiroko

    2016-07-01

    The characteristics of plant growth enhancement effect and the mechanism of the enhancement induced by plasma irradiation are investigated using various active species in plasma. Active oxygen species in oxygen plasma are effective for growth enhancement of plants. DNA microarray analysis of Arabidopsis thaliana indicates that the genes coding proteins that counter oxidative stresses by eliminating active oxygen species are expressed at significantly high levels. The size of plant cells increases owing to oxygen plasma irradiation. The increases in gene expression levels and cell size suggest that the increase in the expression level of the expansin protein is essential for plant growth enhancement phenomena.

  7. An improved, simple, inexpensive and highly flexible hydroponic setup for root mitochondria isolation from arabidopsis and nicotiana pants

    International Nuclear Information System (INIS)

    Hydroponic setups are frequently developed and improved as they are convenient platforms for studying whole plant physiology. Mostly, the available systems produce small amounts of plant material and are therefore, unsuitable for studies requiring large quantities of plant material like isolation of mitochondria. To address this issue, we have modified a hydroponic setup that can sustain hundreds of Arabidopsis and tobacco plants until adult plants are established. The setup is very flexible and easy to construct. It is based on the use of recyclable and sterilizable plastic-net-pots and media containers, which are easily available from the local suppliers. The modified seed-pots and styrofoam sheets facilitate the transfer and harvesting of seedlings. We have used the Percoll based two-step density gradient centrifugation method for the isolation of root mitochondria from the hydroponically grown plants. (author)

  8. Live cell imaging of FM4-64, a tool for tracing the endocytic pathways in Arabidopsis root cells.

    Science.gov (United States)

    Rigal, Adeline; Doyle, Siamsa M; Robert, Stéphanie

    2015-01-01

    Confocal live imaging of the amphiphilic styryl dye FM4-64 is a valuable technique to monitor organelle dynamics and in particular endocytic pathways. After application in plants, FM4-64 immediately stains the plasma membrane and is then integrated on vesicles following endomembrane system-dependent internalization processes. Over time, FM4-64 becomes distributed throughout the full vesicular network from the plasma membrane to the vacuole, including the components of the secretory pathways. Here we provide succinct examples of the many important developmental processes in plants that rely on endocytosis and describe two suitable methods to trace the endocytic pathways in Arabidopsis thaliana root cells based on the uptake of FM4-64. PMID:25408447

  9. Fructose signalling unbalancing and effect on Arabidopsis growth and the photosynthetic pigments content

    OpenAIRE

    Barnes Ontiveros, Rafael; Fiñaga Cortés, Marina; López Rodrigo, Francisco; Noguera Vilches, María Elena; Rodríguez Ibáñez, Claudia; Sahrawy, Mariam; Serrato, Antonio Jesús

    2013-01-01

    Sugar biosynthesis, tightly regulated in plants, depends on photosynthesis as the only biochemical process able to fix atmospheric CO2 in photoautotrophic organisms. In Arabidopsis thaliana, sucrose, glucose, and fructose are the most abundant soluble sugars. Sugar pools are fluctuating during the day/night cycle responding to plant requirements, as the growth stage or the response to diverse environmental stresses. For that reason, plants have developed signalling mechanisms t...

  10. A SCARECROW-RETINOBLASTOMA protein network controls protective quiescence in the Arabidopsis root stem cell organizer.

    OpenAIRE

    Alfredo Cruz-Ramírez; Sara Díaz-Triviño; Guy Wachsman; Yujuan Du; Mario Arteága-Vázquez; Hongtao Zhang; Rene Benjamins; Ikram Blilou; Neef, Anne B.; Vicki Chandler; Ben Scheres

    2013-01-01

    Author Summary In the plant Arabidposis thaliana, root meristems (in the growing tip of the root) contain slowly dividing cells that act as an organizing center for the root stem cells that surround them. This centre is called the quiescent centre (QC). In this study, we show that the slow rate of division in the QC is regulated by the interaction between two proteins: Retinoblastoma homolog (RBR) and SCARECROW (SCR), a transcription factor that controls stem cell maintenance. RBR and SCR reg...

  11. Effects of Conditional IPT-Dependent Cytokinin Overproduction on Root Architecture of Arabidopsis Seedlings

    Czech Academy of Sciences Publication Activity Database

    Kuderová, A.; Urbánková, I.; Válková, M.; Malbeck, Jiří; Brzobohatý, Břetislav; Némethová, D.; Hejátko, J.

    2008-01-01

    Roč. 49, č. 4 (2008), s. 570-582. ISSN 0032-0781 R&D Projects: GA MŠk(CZ) LC06034; GA AV ČR(CZ) IAA600380507 Institutional research plan: CEZ:AV0Z50380511; CEZ:AV0Z50040507 Keywords : Arabidopsis thaliana * Auxin–cytokinin cross-talk * CaMV 35S>GR>ipt transactivation Subject RIV: ED - Physiology Impact factor: 3.542, year: 2008

  12. Tomato root growth, gravitropism, and lateral development: correlation with auxin transport

    Science.gov (United States)

    Muday, G. K.; Haworth, P.

    1994-01-01

    Tomato (Lycopersicon esculentum, Mill.) roots were analyzed during growth on agar plates. Growth of these roots was inhibited by the auxin transport inhibitors naphthylphthalamic acid (NPA) and semicarbazone derivative I (SCB-1). The effect of auxin transport inhibitors on root gravitropism was analyzed by measurement of the angle of gravitropic curvature after the roots were reoriented 90 degrees from the vertical. NPA and SCB-1 abolished both the response of these roots to gravity and the formation of lateral roots, with SCB-1 being the more effective at inhibition. Auxins also inhibited root growth. Both auxins tested has a slight effect on the gravity response, but this effect is probably indirect, since auxins reduced the growth rate. Auxins also stimulated lateral root growth at concentration where primary root growth was inhibited. When roots were treated with both IAA and NPA simultaneously, a cumulative inhibition of root growth was found. When both compounds were applied together, analysis of gravitropism and lateral root formation indicated that the dominant effect was exerted by auxin transport inhibitors. Together, these data suggest a model for the role of auxin transport in controlling both primary and lateral root growth.

  13. Unraveling uranium induced oxidative stress related responses in Arabidopsis thaliana seedlings. Part I: responses in the roots

    International Nuclear Information System (INIS)

    When aiming to evaluate the environmental impact of uranium contamination, it is important to unravel the mechanisms by which plants respond to uranium stress. As oxidative stress seems an important modulator under other heavy metal stress, this study aimed to investigate oxidative stress related responses in Arabidopsis thaliana exposed to uranium concentrations ranging from 0.1 to 100 μM for 1, 3 and 7 days. Besides analyzing relevant reactive oxygen species-producing and -scavenging enzymes at protein and transcriptional level, the importance of the ascorbate-glutathione cycle under uranium stress was investigated. These results are reported separately for roots and leaves in two papers: Part I dealing with responses in the roots and Part II unraveling responses in the leaves and presenting general conclusions. Results of Part I indicate that oxidative stress related responses in the roots were only triggered following exposure to the highest uranium concentration of 100 μM. A fast oxidative burst was suggested based on the observed enhancement of lipoxygenase (LOX1) and respiratory burst oxydase homolog (RBOHD) transcript levels already after 1 day. The first line of defense was attributed to superoxide dismutase (SOD), also triggered from the first day. The enhanced SOD-capacity observed at protein level corresponded with an enhanced expression of iron SOD (FSD1) located in the plastids. For the detoxification of H2O2, an early increase in catalase (CAT1) transcript levels was observed while peroxidase capacities were enhanced at the later stage of 3 days. Although the ascorbate peroxidase capacity and gene expression (APX1) increased, the ascorbate/dehydroascorbate redox balance was completely disrupted and shifted toward the oxidized form. This disrupted balance could not be inverted by the glutathione part of the cycle although the glutathione redox balance could be maintained. - Highlights: → Unravel response mechanisms to uranium stress in Arabidopsis

  14. Unraveling uranium induced oxidative stress related responses in Arabidopsis thaliana seedlings. Part I: responses in the roots

    Energy Technology Data Exchange (ETDEWEB)

    Vanhoudt, Nathalie, E-mail: nvanhoud@sckcen.be [Belgian Nuclear Research Center (SCK-CEN), Biosphere Impact Studies, Boeretang 200, 2400 Mol (Belgium); Hasselt University, Centre for Environmental Sciences, Agoralaan Building D, 3590 Diepenbeek (Belgium); Vandenhove, Hildegarde; Horemans, Nele [Belgian Nuclear Research Center (SCK-CEN), Biosphere Impact Studies, Boeretang 200, 2400 Mol (Belgium); Remans, Tony; Opdenakker, Kelly; Smeets, Karen [Hasselt University, Centre for Environmental Sciences, Agoralaan Building D, 3590 Diepenbeek (Belgium); Bello, Daniel Martinez [Hasselt University, Interuniversity Institute for Biostatistics and Statistical Bioinformatics, Agoralaan Building D, 3590 Diepenbeek (Belgium); Wannijn, Jean; Van Hees, May [Belgian Nuclear Research Center (SCK-CEN), Biosphere Impact Studies, Boeretang 200, 2400 Mol (Belgium); Vangronsveld, Jaco; Cuypers, Ann [Hasselt University, Centre for Environmental Sciences, Agoralaan Building D, 3590 Diepenbeek (Belgium)

    2011-06-15

    When aiming to evaluate the environmental impact of uranium contamination, it is important to unravel the mechanisms by which plants respond to uranium stress. As oxidative stress seems an important modulator under other heavy metal stress, this study aimed to investigate oxidative stress related responses in Arabidopsis thaliana exposed to uranium concentrations ranging from 0.1 to 100 {mu}M for 1, 3 and 7 days. Besides analyzing relevant reactive oxygen species-producing and -scavenging enzymes at protein and transcriptional level, the importance of the ascorbate-glutathione cycle under uranium stress was investigated. These results are reported separately for roots and leaves in two papers: Part I dealing with responses in the roots and Part II unraveling responses in the leaves and presenting general conclusions. Results of Part I indicate that oxidative stress related responses in the roots were only triggered following exposure to the highest uranium concentration of 100 {mu}M. A fast oxidative burst was suggested based on the observed enhancement of lipoxygenase (LOX1) and respiratory burst oxydase homolog (RBOHD) transcript levels already after 1 day. The first line of defense was attributed to superoxide dismutase (SOD), also triggered from the first day. The enhanced SOD-capacity observed at protein level corresponded with an enhanced expression of iron SOD (FSD1) located in the plastids. For the detoxification of H{sub 2}O{sub 2}, an early increase in catalase (CAT1) transcript levels was observed while peroxidase capacities were enhanced at the later stage of 3 days. Although the ascorbate peroxidase capacity and gene expression (APX1) increased, the ascorbate/dehydroascorbate redox balance was completely disrupted and shifted toward the oxidized form. This disrupted balance could not be inverted by the glutathione part of the cycle although the glutathione redox balance could be maintained. - Highlights: > Unravel response mechanisms to uranium stress

  15. Ectopic expression of R3 MYB transcription factor gene OsTCL1 in Arabidopsis, but not rice, affects trichome and root hair formation

    Science.gov (United States)

    Zheng, Kaijie; Tian, Hainan; Hu, Qingnan; Guo, Hongyan; Yang, Li; Cai, Ling; Wang, Xutong; Liu, Bao; Wang, Shucai

    2016-01-01

    In Arabidopsis, a MYB-bHLH-WD40 (MBW) transcriptional activator complex activates the homeodomain protein gene GLABRA2 (GL2), leading to the promotion of trichome formation and inhibition of root hair formation. The same MBW complex also activates single-repeat R3 MYB genes. R3 MYBs in turn, play a negative feedback role by competing with R2R3 MYB proteins for binding bHLH proteins, thus blocking the formation of the MBW complex. By BLASTing the rice (Oryza sativa) protein database using the entire amino acid sequence of Arabidopsis R3 MYB transcription factor TRICHOMELESS1 (TCL1), we found that there are two genes in rice genome encoding R3 MYB transcription factors, namely Oryza sativa TRICHOMELESS1 (OsTCL1) and OsTCL2. Expressing OsTCL1 in Arabidopsis inhibited trichome formation and promoted root hair formation, and OsTCL1 interacted with GL3 when tested in Arabidopsis protoplasts. Consistent with these observations, expression levels of GL2, R2R3 MYB transcription factor gene GLABRA1 (GL1) and several R3 MYB genes were greatly reduced, indicating that OsTCL1 is functional R3 MYB. However, trichome and root hair formation in transgenic rice plants overexpressing OsTCL1 remained largely unchanged, and elevated expression of OsGL2 was observed in the transgenic rice plants, indicating that rice may use different mechanisms to regulate trichome formation. PMID:26758286

  16. Single-cell and coupled GRN models of cell patterning in the Arabidopsis thaliana root stem cell niche

    Directory of Open Access Journals (Sweden)

    Alvarez-Buylla Elena R

    2010-10-01

    Full Text Available Abstract Background Recent experimental work has uncovered some of the genetic components required to maintain the Arabidopsis thaliana root stem cell niche (SCN and its structure. Two main pathways are involved. One pathway depends on the genes SHORTROOT and SCARECROW and the other depends on the PLETHORA genes, which have been proposed to constitute the auxin readouts. Recent evidence suggests that a regulatory circuit, composed of WOX5 and CLE40, also contributes to the SCN maintenance. Yet, we still do not understand how the niche is dynamically maintained and patterned or if the uncovered molecular components are sufficient to recover the observed gene expression configurations that characterize the cell types within the root SCN. Mathematical and computational tools have proven useful in understanding the dynamics of cell differentiation. Hence, to further explore root SCN patterning, we integrated available experimental data into dynamic Gene Regulatory Network (GRN models and addressed if these are sufficient to attain observed gene expression configurations in the root SCN in a robust and autonomous manner. Results We found that an SCN GRN model based only on experimental data did not reproduce the configurations observed within the root SCN. We developed several alternative GRN models that recover these expected stable gene configurations. Such models incorporate a few additional components and interactions in addition to those that have been uncovered. The recovered configurations are stable to perturbations, and the models are able to recover the observed gene expression profiles of almost all the mutants described so far. However, the robustness of the postulated GRNs is not as high as that of other previously studied networks. Conclusions These models are the first published approximations for a dynamic mechanism of the A. thaliana root SCN cellular pattering. Our model is useful to formally show that the data now available are not

  17. Stimulation of Armillaria rhizomorph growth by oak root fungi

    Directory of Open Access Journals (Sweden)

    Hanna Kwaśna

    2014-08-01

    Full Text Available Thirty one different genera of fungi were isolated from the wood of roots of 5O·year·old oak (Quercus robur. The most frequently isolated fungi were: Mycelium radicis atrovirens alpha (MRAA, Clonostachys sp. and Penicillium daleae, Beauveria bassiana, Clonostachys sp., Cryplosporiopsis rodicicolo, Geotrichum candidum, Mortierella vinacea, MRAA, P. daleae, P. janczewskii P. spinulosum, Sporothrix schenckii and Tolypocladium niveum significantly enhanced Armillaria mellea rhizomorph initiation and growth from oak branch segments in vitro. The biggest stimulation effect was noticed when the dematiaceous hyphomycetes, e.g. MRAA, P. dimorphospora and S. schenckii were studied.

  18. Fruit growth in Arabidopsis occurs via DELLA-dependent and DELLA-independent gibberellin responses.

    Science.gov (United States)

    Fuentes, Sara; Ljung, Karin; Sorefan, Karim; Alvey, Elizabeth; Harberd, Nicholas P; Østergaard, Lars

    2012-10-01

    Fruit growth and development depend on highly coordinated hormonal activities. The phytohormone gibberellin (GA) promotes growth by inducing degradation of the growth-repressing DELLA proteins; however, the extent to which DELLA proteins contribute to GA-mediated gynoecium and fruit development remains to be clarified. Here, we provide an in-depth characterization of the role of DELLA proteins in Arabidopsis thaliana fruit growth. We show that DELLA proteins are key regulators of reproductive organ size and important for ensuring optimal fertilization. We demonstrate that the seedless fruit growth (parthenocarpy) observed in della mutants can be directly attributed to the constitutive activation of GA signaling. It has been known for >75 years that another hormone, auxin, can induce formation of seedless fruits. Using mutants with complete lack of DELLA activity, we show here that auxin-induced parthenocarpy occurs entirely through GA signaling in Arabidopsis. Finally, we uncover the existence of a DELLA-independent GA response that promotes fruit growth. This response requires GIBBERELLIN-INSENSITIVE DWARF1-mediated GA perception and a functional 26S proteasome and involves the basic helix-loop-helix protein SPATULA as a key component. Taken together, our results describe additional complexities in GA signaling during fruit development, which may be particularly important to optimize the conditions for successful reproduction. PMID:23064323

  19. Improving root-zone soil moisture estimations using dynamic root growth and crop phenology

    Science.gov (United States)

    Hashemian, Minoo; Ryu, Dongryeol; Crow, Wade T.; Kustas, William P.

    2015-12-01

    Water Energy Balance (WEB) Soil Vegetation Atmosphere Transfer (SVAT) modelling can be used to estimate soil moisture by forcing the model with observed data such as precipitation and solar radiation. Recently, an innovative approach that assimilates remotely sensed thermal infrared (TIR) observations into WEB-SVAT to improve the results has been proposed. However, the efficacy of the model-observation integration relies on the model's realistic representation of soil water processes. Here, we explore methods to improve the soil water processes of a simple WEB-SVAT model by adopting and incorporating an exponential root water uptake model with water stress compensation and establishing a more appropriate soil-biophysical linkage between root-zone moisture content, above-ground states and biophysical indices. The existing WEB-SVAT model is extended to a new Multi-layer WEB-SVAT with Dynamic Root distribution (MWSDR) that has five soil layers. Impacts of plant root depth variations, growth stages and phenological cycle of the vegetation on transpiration are considered in developing stages. Hydrometeorological and biogeophysical measurements collected from two experimental sites, one in Dookie, Victoria, Australia and the other in Ponca, Oklahoma, USA, are used to validate the new model. Results demonstrate that MWSDR provides improved soil moisture, transpiration and evaporation predictions which, in turn, can provide an improved physical basis for assimilating remotely sensed data into the model. Results also show the importance of having an adequate representation of vegetation-related transpiration process for an appropriate simulation of water transfer in a complicated system of soil, plants and atmosphere.

  20. Induction of Root Hair Growth in a Phosphorus-Buffered Culture Solution

    Institute of Scientific and Technical Information of China (English)

    LIU Guo-dong; James Dunlop; Thai Phung

    2006-01-01

    A system to control the release of phosphate in water was successfully established, based on solubility product of [Ca2+] and [PO43-] using tricalcium phosphate as P source in the hydroponic solution, and adding CaC12 for supplementing extra Ca2+. The system, similar to soil solutions, was a P nutrient buffer solution with very low bioavailable P. The buffer solution induced the roots of both monocotyledon and dicotyledon species to grow abundant root hairs, 3 mm in maximum length. The monocotyledons were corn (Zea mays L.) (var. Yellow Rose), wheat (Triticum aestivum L.) (var.Yanzhong 144), Triticale secale L. (var. Jingsong 5), and ryegrass (Lolium rigidum L.) (var. Ruanni), and the dicotyledons were Arabidopsis thaliana L. (var. Columbia), white clover (Trifolium repens) (var. Kopu), Lotus (Lotus peduncucatus Cav. Luliginosus Schkuhr) (var. Grasslands Maku). For these species we proved that the root environment controls the induction of root hair formation. However, the hydroponic buffer solution failed to induce root hairs on the roots of onion (Allium cepa L.). Other investigators have concluded that corn does not form root hairs in hydroponics, but abundant long root hairs on corn were induced by this buffer system. The roots with abundant long root hairs are called "hedgehog roots" because they have hairs everywhere just like a hedgehog.

  1. Nano titania aided clustering and adhesion of beneficial bacteria to plant roots to enhance crop growth and stress management

    Science.gov (United States)

    Palmqvist, N. G. M.; Bejai, S.; Meijer, J.; Seisenbaeva, G. A.; Kessler, V. G.

    2015-05-01

    A novel use of Titania nanoparticles as agents in the nano interface interaction between a beneficial plant growth promoting bacterium (Bacillus amyloliquefaciens UCMB5113) and oilseed rape plants (Brassica napus) for protection against the fungal pathogen Alternaria brassicae is presented. Two different TiO2 nanoparticle material were produced by the Sol-Gel approach, one using the patented Captigel method and the other one applying TiBALDH precursor. The particles were characterized by transmission electron microscopy, thermogravimetric analysis, X-ray diffraction, dynamic light scattering and nano particle tracking analysis. Scanning electron microscopy showed that the bacterium was living in clusters on the roots and the combined energy-dispersive X-ray spectroscopy analysis revealed that titanium was present in these cluster formations. Confocal laser scanning microscopy further demonstrated an increased bacterial colonization of Arabidopsis thaliana roots and a semi-quantitative microscopic assay confirmed an increased bacterial adhesion to the roots. An increased amount of adhered bacteria was further confirmed by quantitative fluorescence measurements. The degree of infection by the fungus was measured and quantified by real-time-qPCR. Results showed that Titania nanoparticles increased adhesion of beneficial bacteria on to the roots of oilseed rape and protected the plants against infection.

  2. Aluminium-induced ion transport in Arabidopsis: the relationship between Al tolerance and root ion flux

    OpenAIRE

    Bose, Jayakumar; Babourina, Olga; Shabala, Sergey; RENGEL, ZED

    2010-01-01

    Aluminium (Al) rhizotoxicity coincides with low pH; however, it is unclear whether plant tolerance to these two factors is controlled by the same mechanism. To address this question, the Al-resistant alr104 mutant, two Al-sensitive mutants (als3 and als5), and wild-type Arabidopsis thaliana were compared in long-term exposure (solution culture) and in short-term exposure experiments (H+ and K+ fluxes, rhizosphere pH, and plasma membrane potential, E m). Based on biomass accumulation, als5 and...

  3. Integration of hormonal signaling networks and mobile microRNAs is required for vascular patterning in Arabidopsis roots

    KAUST Repository

    Muraro, D.

    2013-12-31

    As multicellular organisms grow, positional information is continually needed to regulate the pattern in which cells are arranged. In the Arabidopsis root, most cell types are organized in a radially symmetric pattern; however, a symmetry-breaking event generates bisymmetric auxin and cytokinin signaling domains in the stele. Bidirectional cross-talk between the stele and the surrounding tissues involving a mobile transcription factor, SHORT ROOT (SHR), and mobile microRNA species also determines vascular pattern, but it is currently unclear how these signals integrate. We use a multicellular model to determine a minimal set of components necessary for maintaining a stable vascular pattern. Simulations perturbing the signaling network show that, in addition to the mutually inhibitory interaction between auxin and cytokinin, signaling through SHR, microRNA165/6, and PHABULOSA is required to maintain a stable bisymmetric pattern. We have verified this prediction by observing loss of bisymmetry in shr mutants. The model reveals the importance of several features of the network, namely the mutual degradation of microRNA165/6 and PHABULOSA and the existence of an additional negative regulator of cytokinin signaling. These components form a plausible mechanism capable of patterning vascular tissues in the absence of positional inputs provided by the transport of hormones from the shoot.

  4. Plant-growth promoting effect of newly isolated rhizobacteria varies between two Arabidopsis ecotypes

    OpenAIRE

    Schwachtje, Jens; Karojet, Silke; Kunz, Sabine; Brouwer, Stephan; van Dongen, Joost T.

    2012-01-01

    Various rhizobacteria are known for their beneficial effects on plants, i. e. promotion of growth and induction of systemic resistance against pathogens. These bacteria are categorized as plant growth promoting rhizobacteria (PGPR) and are associated with plant roots. Knowledge of the underlying mechanisms of plant growth promotion in vivo is still very limited, but interference of bacteria with plant hormone metabolism is suggested to play a major role. To obtain new growth promoting bacteri...

  5. Probing the reproducibility of leaf growth and molecular phenotypes: A comparison of three Arabidopsis accessions cultivated in ten laboratories

    OpenAIRE

    Massonnet, Catherine; Vile, Denis; Fabre, Juliette; Hannah, Matthew A; Caldana, C.; Lisec, J.; Beemster, G.T.S.; Meyer, R. C.; Messerli, G.; Gronlund, J.T.; Perkovic, J.; Wigmore, E.; May, S.; Bevan, M. W.; Meyer, Christian

    2010-01-01

    A major goal of the life sciences is to understand how molecular processes control phenotypes. Because understanding biological systems relies on the work of multiple laboratories, biologists implicitly assume that organisms with the same genotype will display similar phenotypes when grown in comparable conditions. We investigated to what extent this holds true for leaf growth variables and metabolite and transcriptome profiles of three Arabidopsis (Arabidopsis thaliana) genotypes grown in 10...

  6. On the role of a Lipid-Transfer Protein. Arabidopsis ltp3 mutant is compromised in germination and seedling growth.

    OpenAIRE

    Pagnussat, Luciana A; Oyarburo, Natalia; Cimmino, Carlos; Pinedo, Marcela L; de la Canal, Laura

    2015-01-01

    Plant Lipid-Transfer Proteins (LTPs) exhibit the ability to reversibly bind/transport lipids in vitro. LTPs have been involved in diverse physiological processes but conclusive evidence on their role has only been presented for a few members, none of them related to seed physiology. Arabidopsis seeds rely on storage oil breakdown to supply carbon skeletons and energy for seedling growth. Here, Arabidopsis ltp3 mutant was analyzed for its ability to germinate and for seedling establishment. Lt...

  7. Gene Networks Involved in Hormonal Control of Root Development in Arabidopsis thaliana: A Framework for Studying Its Disturbance by Metal Stress

    OpenAIRE

    Stefanie De Smet; Ann Cuypers; Jaco Vangronsveld; Tony Remans

    2015-01-01

    Plant survival under abiotic stress conditions requires morphological and physiological adaptations. Adverse soil conditions directly affect root development, although the underlying mechanisms remain largely to be discovered. Plant hormones regulate normal root growth and mediate root morphological responses to abiotic stress. Hormone synthesis, signal transduction, perception and cross-talk create a complex network in which metal stress can interfere, resulting in root growth alterations...

  8. Root growth and soil nitrogen depletion by onion, lettuce, early cabbage and carrot

    OpenAIRE

    Thorup-Kristensen, K

    2001-01-01

    Experiments examining root growth, the utilization of N and the effect of green manures were carried out on four vegetable crops. Large differences were observed both in rooting depth penetration rates, and in final rooting depth and distribution. Onion had a very low depth penetration rate, carrot an intermediate rate, and lettuce and cabbage showed high rates. A combination of depth penetration rates and duration of growth determined rooting depth at harvest. Therefore, lettuce, which had a...

  9. Pseudomonas fluorescens and Pseudomonas putida for Promoting Growth of Jatropha curcas Seedling Root

    Directory of Open Access Journals (Sweden)

    Sri Sumarsih

    2012-05-01

    Full Text Available Pseudomonas fluorescens and P. putida are Plant Growth Promoting Rhizobacteria (PGPR that can produce growth hormone. The objective of this study is to know the effects of those two combined species of PGPR on seedling root growth of Jatropha curcas. The condition of the seedling root determines the success of dry land cultivation. The root which has wider coverage, is larger in number, and is bigger in diameter makes seedling more resistant to stress in dry land environment. In the experiment, two kinds of plant materials are used for seedling, the Jatropha seed and stem material, which are treated in a mixed culture of PGPR. For the Jatropha seed, this mixed culture of PGPR is given at the same time of cultivating the sprout on the seedling medium. For the stem cutting, the PGPR is poured in together during the first watering of the seedling cultivation medium. In the fourthweek, the observed growth parameters are root length, root diameter, primary and secondary lateral root numbers, Root Length Density (RLD, Frequency of Lateral Root (FLR, and Specific Root Length (SRL. These data are analyzed using analysis of variant with DMRT test at 0.05 level of significance. The result of this study shows that PGPR tend to reduce FLR values on the seedling root made from seeds. On the seedling root made from stem cutting, PGPR increase the root length, primary and secondary lateral root numbers, root diameter, FLR and SRL values as well.

  10. Arabidopsis thaliana as a tool to identify traits involved in Verticillium dahliae biocontrol by the olive root endophyte Pseudomonas fluorescens PICF7.

    Science.gov (United States)

    Maldonado-González, M Mercedes; Bakker, Peter A H M; Prieto, Pilar; Mercado-Blanco, Jesús

    2015-01-01

    The effective management of Verticillium wilts (VW), diseases affecting many crops and caused by some species of the soil-borne fungus Verticillium, is problematic. The use of microbial antagonists to control these pathologies fits modern sustainable agriculture criteria. Pseudomonas fluorescens PICF7 is an endophytic bacterium isolated from olive roots with demonstrated ability to control VW of olive caused by the highly virulent, defoliating (D) pathotype of Verticillium dahliae Kleb. However, the study of the PICF7-V. dahliae-olive tripartite interaction poses difficulties because of the inherent characteristics of woody, long-living plants. To overcome these problems we explored the use of the model plant Arabidopsis thaliana. Results obtained in this study showed that: (i) olive D and non-defoliating V. dahliae pathotypes produce differential disease severity in A. thaliana plants; (ii) strain PICF7 is able to colonize and persist in the A. thaliana rhizosphere but is not endophytic in Arabidopsis; and (iii) strain PICF7 controls VW in Arabidopsis. Additionally, as previously observed in olive, neither swimming motility nor siderophore production by PICF7 are required for VW control in A. thaliana, whilst cysteine auxotrophy decreased the effectiveness of PICF7. Moreover, when applied to the roots PICF7 controlled Botrytis cinerea infection in the leaves of Arabidopsis, suggesting that this strain is able to induce systemic resistance. A. thaliana is therefore a suitable alternative to olive bioassays to unravel biocontrol traits involved in biological control of V. dahliae by P. fluorescens PICF7. PMID:25904904

  11. Advancements in Root Growth Measurement Technologies and Observation Capabilities for Container-Grown Plants

    Directory of Open Access Journals (Sweden)

    Lesley A. Judd

    2015-07-01

    Full Text Available The study, characterization, observation, and quantification of plant root growth and root systems (Rhizometrics has been and remains an important area of research in all disciplines of plant science. In the horticultural industry, a large portion of the crops grown annually are grown in pot culture. Root growth is a critical component in overall plant performance during production in containers, and therefore it is important to understand the factors that influence and/or possible enhance it. Quantifying root growth has varied over the last several decades with each method of quantification changing in its reliability of measurement and variation among the results. Methods such as root drawings, pin boards, rhizotrons, and minirhizotrons initiated the aptitude to measure roots with field crops, and have been expanded to container-grown plants. However, many of the published research methods are monotonous and time-consuming. More recently, computer programs have increased in use as technology advances and measuring characteristics of root growth becomes easier. These programs are instrumental in analyzing various root growth characteristics, from root diameter and length of individual roots to branching angle and topological depth of the root architecture. This review delves into the expanding technologies involved with expertly measuring root growth of plants in containers, and the advantages and disadvantages that remain.

  12. Nonfumigant Nematicides for Control of Root-knot Nematode to Protect Carrot Root Growth in Organic Soils.

    Science.gov (United States)

    Vrain, T C; Belair, G; Martel, P

    1979-10-01

    Greenhouse tests were conducted to determine the effects of two kinds of Meloidogyne hapla inoculum on the growth and quality of carrot roots, and the protection afforded in each case by nonfumigant nematicides in organic soils. For all treatments the percentage of carrots damaged was greater with larvae alone as inoculum than with larvae and eggs, indicating that most of the damage occurs early during formation of the taproot. Fosthietan, aldicarb, and oxamyl at 4 and 6 kg ai/ha protected the roots during formation and gave a lasting control of root-knot nematode. There was some nematode damage to the roots with phenamiphos and carbofuran at 4 and 6 kg ai/ha. Isazophos, diflubenzuron, and fenvalerate gave little protection to carrot roots and did not control root-knot nematode effectively. PMID:19300652

  13. Root growth of perennials in vertical growing media for use in green walls

    DEFF Research Database (Denmark)

    Jørgensen, Lars; Dresbøll, Dorte Bodin; Thorup-Kristensen, Kristian

    2014-01-01

    . Five species of hardy perennials (Campanula poscharskyana ‘Stella’, Fragaria vesca ‘Småland’, Geranium sanguineum ‘Max Frei’, Sesleria heufleriana and Veronica officinalis ‘Allgrün’) were grown in 3 types of growing media (coir and 2 of rockwool) in vertical boxes under greenhouse conditions. Root....... Fragaria, Geranium and Veronica showed steadily increasing root growth throughout the experiment, whereas Campanula started slow, but showed a strong root growth towards the end of the experiment. Sesleria showed little root growth throughout the experiment. Dry weight and root activity measured as 15N...

  14. Effects of N fertilizer on root growth in Zea mays L. seedlings

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Z. R.; Rui, Y. R.; Shen, J. B.; Zhang, F. S.

    2008-07-01

    This paper reports the effects of different nitrogen (N) fertilizer levels on the growth of maize (Zea mays L.) under field conditions. The N supply was found to influence the growth of the plants, especially the roots. A high N supply significantly inhibited root elongation, and was associated with reduced root dry weight compared to controls and to plants grown with smaller supplies of N. However, no differences were seen in lateral primary root density under the different N supply conditions, nor did plant N concentration increase with high N supply. In conclusion, a high N supply not only wastes resources and pollutes the environment, it may also inhibit root growth. (Author)

  15. Rhizobacterial volatiles and photosynthesis-related signals coordinate MYB72 expression in Arabidopsis roots during onset of induced systemic resistance and iron-deficiency responses

    OpenAIRE

    2015-01-01

    In Arabidopsis roots, the transcription factor MYB72 plays a dual role in the onset of rhizobacteria-induced systemic resistance (ISR) and plant survival under conditions of limited iron availability. Previously, it was shown that MYB72 coordinates the expression of a gene module that promotes synthesis and excretion of iron-mobilizing phenolic compounds in the rhizosphere, a process that is involved in both iron acquisition and ISR signaling. Here, we show that volatile organic compounds (VO...

  16. The response of Arabidopsis root water transport to a challenging environment implicates reactive oxygen species- and phosphorylation-dependent internalization of aquaporins

    OpenAIRE

    Boursiac, Yann; Prak, Sodana; Boudet, Julie; Postaire, Olivier; Luu, Doan-Trung; Tournaire-Roux, Colette; Santoni, Véronique; Maurel, Christophe

    2008-01-01

    Aquaporins, which facilitate the diffusion of water across biological membranes, are key molecules for the regulation of water transport at the cell and organ levels. We recently reported that hydrogen peroxide (H2O2) acts as an intermediate in the regulation of Arabidopsis root water transport and aquaporins in response to NaCl and salicylic acid (SA).1 Its action involves signaling pathways and an internalization of aquaporins from the cell surface. The present addendum connects these findi...

  17. Exogenous auxin alleviates cadmium toxicity in Arabidopsis thaliana by stimulating synthesis of hemicellulose 1 and increasing the cadmium fixation capacity of root cell walls

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Xiao Fang [Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, College of Life Sciences, Zhejiang University, Hangzhou 310058 (China); State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou 310058 (China); Wang, Zhi Wei [Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, College of Life Sciences, Zhejiang University, Hangzhou 310058 (China); Dong, Fang; Lei, Gui Jie [State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou 310058 (China); Shi, Yuan Zhi [The Key Laboratory of Tea Chemical Engineering, Ministry of Agriculture, Yunqi Road 1, Hangzhou 310008 (China); Li, Gui Xin, E-mail: guixinli@zju.edu.cn [College of Agronomy and Biotechnology, Zhejiang University, Hangzhou 310058 (China); Zheng, Shao Jian [Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, College of Life Sciences, Zhejiang University, Hangzhou 310058 (China); State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou 310058 (China)

    2013-12-15

    Highlights: • Cd reduces endogenous auxin levels in Arabidopsis. • Exogenous applied auxin NAA increases Cd accumulation in the roots but decreases in the shoots. • NAA increases cell wall hemicellulose 1 content. • Hemicellulose 1 retains Cd and makes it difficult to be translocated to shoots. • NAA rescues Cd-induced chlorosis. -- Abstract: Auxin is involved in not only plant physiological and developmental processes but also plant responses to abiotic stresses. In this study, cadmium (Cd{sup 2+}) stress decreased the endogenous auxin level, whereas exogenous auxin (α-naphthaleneacetic acid, NAA, a permeable auxin analog) reduced shoot Cd{sup 2+} concentration and rescued Cd{sup 2+}-induced chlorosis in Arabidopsis thaliana. Under Cd{sup 2+} stress conditions, NAA increased Cd{sup 2+} retention in the roots and most Cd{sup 2+} in the roots was fixed in hemicellulose 1 of the cell wall. NAA treatment did not affect pectin content and its binding capacity for Cd{sup 2+}, whereas it significantly increased the content of hemicellulose 1 and the amount of Cd{sup 2+} retained in it. There were highly significant correlations between Cd{sup 2+} concentrations in the root, cell wall and hemicellulose 1 when the plants were subjected to Cd{sup 2+} or NAA + Cd{sup 2+} treatment for 1 to 7 d, suggesting that the increase in hemicellulose 1 contributes greatly to the fixation of Cd{sup 2+} in the cell wall. Taken together, these results demonstrate that auxin-induced alleviation of Cd{sup 2+} toxicity in Arabidopsis is mediated through increasing hemicellulose 1 content and Cd{sup 2+} fixation in the root, thus reducing the translocation of Cd{sup 2+} from roots to shoots.

  18. Soil acidity and its relationship to root growth in declining forest stands in Germany

    Energy Technology Data Exchange (ETDEWEB)

    Matzner, E.; Murach, D.; Fortmann, H.

    1986-11-01

    Ingrowth core studies were used to investigate the influence of 3 different soils on root growth of Norway spruce in two stands in Northwest Germany. Root growth was significantly inhibited by the acid soil treatment. The amount of roots which had grown into the limed ingrowth cores was much higher and the percentage of dead roots was less when compared to the unlimed treatment. This is attributed to improved Ca/Al-ratios after liming. The fertilized peat-sand soil delivered optimal conditions for root growth indicated by maximum root biomass and 0% root mortality. The importance of soil acidification induced by acid deposition as the cause of the root disturbance in declining stands is addressed. 33 references.

  19. Pseudomonas fluorescens and Pseudomonas putida for Promoting Growth of Jatropha curcas Seedling Root

    OpenAIRE

    Sri Sumarsih; Darban Haryanto

    2012-01-01

    Pseudomonas fluorescens and P. putida are Plant Growth Promoting Rhizobacteria (PGPR) that can produce growth hormone. The objective of this study is to know the effects of those two combined species of PGPR on seedling root growth of Jatropha curcas. The condition of the seedling root determines the success of dry land cultivation. The root which has wider coverage, is larger in number, and is bigger in diameter makes seedling more resistant to stress in dry land environment. In the experime...

  20. Detecting autophagy in Arabidopsis roots by membrane-permeable cysteine protease inhibitor E-64d and endocytosis tracer FM4–64

    OpenAIRE

    Oh-ye, Yuumi; Inoue, Yuko; Moriyasu, Yuji

    2011-01-01

    Autophagy is the process by which cells degrade their own components in lysosomes or vacuoles. Autophagy in tobacco BY-2 cells cultured in sucrose-free medium takes place in formed, autolysosomes in the presence of a cysteine protease inhibitor. The autolysosomes in BY-2 cells are located in the endocytotic pathway and thus can be stained with fluorescent endocytosis marker FM4–64. In the present study, in order to detect autophagy in the root cells of Arabidopsis, we incubated root tips from...

  1. Arabidopsis CAP1-mediated ammonium sensing required reactive oxygen species in plant cell growth.

    Science.gov (United States)

    Bai, Ling; Zhou, Yun; Ma, Xiaonan; Gao, Lijie; Song, Chun-Peng

    2014-06-18

    [Ca (2+)]cyt-associated protein kinase (CAP) gene 1 is a receptor-like kinase that belongs to CrRLK1L (Catharanthus roseus Receptor like kinase) subfamily. CAP1 has been identified as a novel modulator of NH 4(+) in the tonoplast, which regulates root hair growth by maintaining the cytoplasmic Ca (2+) gradients. Different expression pattern of tonoplast intrinsic protein (TIP2;3) in the CAP1 knock out mutant and wild type on Murashige and Skoog (MS) medium suggested that CAP1 influences transport activity to regulate the compartmentalization of NH 4(+) into vacuole. Lower expression level of Oxidative Signal-Inducible1(OXI1) in the cap1-1 root and the abnormal reactive oxygen species (ROS) gradient in root hair of cap1-1 on MS medium indicated that ROS signaling involve in CAP1-regulated root hair growth. Wild-type-like ROS distribution pattern in the cap1-1 root hair can be reestablished in seedlings grown on NH 4(+) deficient medium, which indicated that CAP1 functions as a sensor for NH 4(+) signaling in maintaining tip-focused ROS gradient in root hairs polar growth. PMID:24940875

  2. Effect of calmodulin antagonists on the growth and graviresponsiveness of primary roots of maize

    Science.gov (United States)

    Stinemetz, C. L.; Hasenstein, K. H.; Young, L. M.; Evans, M. L.

    1992-01-01

    We examined the effect of calmodulin (CaM) antagonists applied at the root tip on root growth, gravity-induced root curvature, and the movement of calcium across the root tip and auxin (IAA) across the elongation zone of gravistimulated roots. All of the CaM antagonists used in these studies delayed gravity-induced curvature at a concentration (1 micromole) that did not affect root growth. Calmodulin antagonists (> or = 1 micromole) inhibited downward transport of label from 45Ca2+ across the caps of gravistimulated roots relative to the downward transport of 45Ca2+ in gravistimulated roots which were not treated with CaM antagonists. Application of CaM antagonists at the root tip (> or = 1 micromole) also decreased the relative downward movement of label from 3H-IAA applied to the upper side of the elongation zone of gravistimulated roots. In general, tip application of antagonists inhibited neither the upward transport of 45Ca2+ in the root tip nor the upward movement of label from 3H-IAA in the elongation zone of gravistimulated roots. Thus, roots treated with CaM antagonists > or = 1 micromole become less graviresponsive and exhibit reduced or even a reversal of downward polarity of calcium transport across the root tip and IAA transport across the elongation zone. The results indicate that calmodulin-regulated events play a role in root gravitropism.

  3. Mathematical Modeling and Experimental Validation of the Spatial Distribution of Boron in the Root of Arabidopsis thaliana Identify High Boron Accumulation in the Tip and Predict a Distinct Root Tip Uptake Function

    OpenAIRE

    Shimotohno, Akie; Sotta, Naoyuki; Sato, Takafumi; De Ruvo, Micol; Marée, Athanasius F.M.; Verônica A Grieneisen; Fujiwara, Toru

    2015-01-01

    Boron, an essential micronutrient, is transported in roots of Arabidopsis thaliana mainly by two different types of transporters, BORs and NIPs (nodulin26-like intrinsic proteins). Both are plasma membrane localized, but have distinct transport properties and patterns of cell type-specific accumulation with different polar localizations, which are likely to affect boron distribution. Here, we used mathematical modeling and an experimental determination to address boron distributions in the ro...

  4. Hpa1 harpin needs nitroxyl terminus to promote vegetative growth and leaf photosynthesis in Arabidopsis

    Indian Academy of Sciences (India)

    Xiaojie Li; Liping Han; Yanying Zhao; Zhenzhen You; Chunling Zhang; Zhenzhen You; Hansong Dong; Chunling Zhang

    2014-03-01

    Hpa1 is a harpin protein produced by Xanthomonas oryzae, an important bacterial pathogen of rice, and has the growth-promoting activity in plants. To understand the molecular basis for the function of Hpa1, we generated an inactive variant protein, Hpa1NT, by deleting the nitroxyl-terminal region of the Hpa1 sequence and compared Hpa1NT with the full-length protein in terms of the effects on vegetative growth and related physiological responses in Arabidopsis. When Hpa1 was applied to plants, it acted to enhance the vegetative growth but did not affect the floral development. Enhanced plant growth was accompanied by induced expression of growth-promoting genes in plant leaves. The growth-promoting activity of Hpa1 was further correlated with a physiological consequence shown as promoted leaf photosynthesis as a result of facilitated CO2 conduction through leaf stomata and mesophyll cells. On the contrary, plant growth, growth-promoting gene expression, and the physiological consequence changed little in response to the Hpa1NT treatment. These analyses suggest that Hpa1 requires the nitroxyl-terminus to facilitate CO2 transport inside leaf cells and promote leaf photosynthesis and vegetative growth of the plant.

  5. Ectopic Expression of the Chinese Cabbage Malate Dehydrogenase Gene Promotes Growth and Aluminum Resistance in Arabidopsis.

    Science.gov (United States)

    Li, Qing-Fei; Zhao, Jing; Zhang, Jing; Dai, Zi-Hui; Zhang, Lu-Gang

    2016-01-01

    Malate dehydrogenases (MDHs) are key metabolic enzymes that play important roles in plant growth and development. In the present study, we isolated the full-length and coding sequences of BraMDH from Chinese cabbage [Brassica campestris L. ssp. pekinensis (Lour) Olsson]. We conducted bioinformatics analysis and a subcellular localization assay, which revealed that the BraMDH gene sequence contained no introns and that BraMDH is localized to the chloroplast. In addition, the expression pattern of BraMDH in Chinese cabbage was investigated, which revealed that BraMDH was heavily expressed in inflorescence apical meristems, as well as the effect of BraMDH overexpression in two homozygous transgenic Arabidopsis lines, which resulted in early bolting and taller inflorescence stems. Furthermore, the fresh and dry weights of aerial tissue from the transgenic Arabidopsis plants were significantly higher than those from the corresponding wild-type plants, as were plant height, the number of rosette leaves, and the number of siliques produced, and the transgenic plants also exhibited stronger aluminum resistance when treated with AlCl3. Therefore, our results suggest that BraMDH has a dramatic effect on plant growth and that the gene is involved in both plant growth and aluminum resistance. PMID:27536317

  6. The overexpression of an Amaranthus hypochondriacus NF-YC gene modifies growth and confers water deficit stress resistance in Arabidopsis.

    Science.gov (United States)

    Palmeros-Suárez, Paola A; Massange-Sánchez, Julio A; Martínez-Gallardo, Norma A; Montero-Vargas, Josaphat M; Gómez-Leyva, Juan F; Délano-Frier, John P

    2015-11-01

    Nuclear factor-Y (NF-Y), is a plant heterotrimeric transcription factor constituted by NF-YA, NF-YB and NF-YC subunits. The function of many NF-Y subunits, mostly of the A and B type, has been studied in plants, but knowledge regarding the C subunit remains fragmentary. Here, a water stress-induced NF-YC gene from Amaranthus hypochondriacus (AhNF-YC) was further characterized by its overexpression in transgenic Arabidospis thaliana plants. A role in development was inferred from modified growth rates in root, rosettes and inflorescences recorded in AhNF-YC overexpressing Arabidopsis plants, in addition to a delayed onset of flowering. Also, the overexpression of AhNF-YC caused increased seedling sensitivity to abscisic acid (ABA), and influenced the expression of several genes involved in secondary metabolism, development and ABA-related responses. An altered expression of the latter in water stressed and recovered transgenic plants, together with the observed increase in ABA sensitivity, suggested that their increased water stress resistance was partly ABA-dependent. An untargeted metabolomic analysis also revealed an altered metabolite pattern, both in normal and water stress/recovery conditions. These results suggest that AhNF-YC may play an important regulatory role in both development and stress, and represents a candidate gene for the engineering of abiotic stress resistance in commercial crops. PMID:26475185

  7. Arabidopsis thaliana AtUTr7 Encodes a Golgi-Localized UDP-Glucose/UDP-Galactose Transporter that Affects Lateral Root Emergence

    Institute of Scientific and Technical Information of China (English)

    Michael Handford; Cecilia Rodríguez-Furlán; Lorena Marchant; Marcelo Segura; Daniela Gómez; Elena Alvarez-Buyll; Guang-Yan Xiong; Markus Pauly; Ariel Orellana

    2012-01-01

    Nucleotide sugar transporters (NSTs) are antiporters comprising a gene family that plays a fundamental role in the biosynthesis of complex cell wall polysaccharides and glycoproteins in plants.However,due to the limited number of related mutants that have observable phenotypes,the biological function(s) of most NSTs in cell wall biosynthesis and assembly have remained elusive.Here,we report the characterization of AtUTr7 from Arabidopsis (Arabidopsis thaliana (L.) Heynh.),which is homologous to multi-specific UDP-sugar transporters from Drosophila melanogaster,humans,and Caenorhabditis elegans.We show that AtUTr7 possesses the common structural characteristics conserved among NSTs.Using a green fluorescent protein (GFP) tagged version,we demonstrate that AtUTr7 is localized in the Golgi apparatus.We also show that AtUTr7 is widely expressed,especially in the roots and in specific floral organs.Additionally,the results of an in vitro nucleotide sugar transport assay carried out with a tobacco and a yeast expression system suggest that AtUTr7 is capable of transferring UDP-Gal and UDP-GIc,but not a range of other UDP-and GDP-sugars,into the Golgi lumen.Mutants lacking expression of AtUTr7 exhibited an early proliferation of lateral roots as well as distorted root hairs when cultivated at high sucrose concentrations.Furthermore,the distribution of homogalacturonan with a low degree of methyl esterification differed in lateral root tips of the mutant compared to wild-type plants,although additional analytical procedures revealed no further differences in the composition of the root cell walls.This evidence suggests that the transport of UDP-Gal and UDP-GIc into the Golgi under conditions of high root biomass production plays a role in lateral root and root hair development.

  8. Arabidopsis thaliana as a tool to identify traits involved in Verticillium dahliae biocontrol by the olive root endophyte Pseudomonas fluorescens PICF7

    Directory of Open Access Journals (Sweden)

    M. Mercedes eMaldonado-González

    2015-04-01

    Full Text Available The effective management of Verticillium wilts, diseases affecting many crops and caused by some species of the soil-borne fungus Verticillium, is problematic. The use of microbial antagonists to control these pathologies fits modern sustainable agriculture criteria. Pseudomonas fluorescens PICF7 is an endophytic bacterium isolated from olive roots with demonstrated ability to control Verticillium wilt of olive caused by the highly-virulent, defoliating (D pathotype of Verticillium dahliae Kleb. However, the study of the PICF7-V.dahliae-olive tripartite interaction poses difficulties because of the inherent characteristics of woody, long-living plants. To overcome these problems we explored the use of the model plant Arabidopsis thaliana. Results obtained in this study showed that: (i olive D and non-defoliating (ND V. dahliae pathotypes produce differential disease severity in A. thaliana plants; (ii strain PICF7 is able to colonize and persist in the A. thaliana rhizosphere but is not endophytic in Arabidopsis; and (iii strain PICF7 controls Verticillium wilt (VW in Arabidopsis. Additionally, as previously observed in olive, neither swimming motility nor siderophore production by PICF7 are required for VW control in A. thaliana, whilst cysteine auxotrophy decreased the effectiveness of PICF7. Moreover, when applied to the roots PICF7 controlled Botrytis cinerea infection in the leaves of Arabidopsis, suggesting that this strain is able to induce systemic resistance. Arabidopsis thaliana is therefore a suitable alternative to olive bioassays to unravel biocontrol traits involved in biological control of V. dahliae by P. fluorescens PICF7.

  9. Oxidative stress response in Arabidopsis thaliana roots and leaves exposed to cadmium, uranium or a combination of both stressors

    International Nuclear Information System (INIS)

    Nuclear energy production or NORM industry released low amounts of radioactive substances together with non-radioactive substances (e.g., heavy metals, organic chemicals) to the environment. As sessile organisms, plants are commonly exposed to a number of adverse conditions and therefore it is interesting to study the stress responses of plants induced by the single stressors as well as in a in a multi-pollution set-up. The aim of this study was to understand and predict fast induced oxidative stress responses in plants exposed to Cd and U or a combination of both stressors. Arabidopsis thaliana plants grown hydroponically for 18 days were exposed to a Cd (5 μM) or 238U (25 μM) or an equi-toxic mixture of Cd and 238U (2.5 μM + 12.5 μM) for 24 h. As expected both metals were taken up into the plants with Cd being more readily transported to the leaves than U. The root-to-shoot ratio was approximately 1,3 for Cd whereas it was above 3500 for U. For both U and Cd the root-to-shoot ratio was not affected under multiple exposure conditions used here. Notwithstanding the limited exposure time, leave and root fresh weight was already decreasing in U-treated plants. For Cd or Cd+U a decreasing but at this point not significant trend was visible. As U concentrations in the leaves were very low the decrease in leaf fresh weight is possibly due to signaling from the roots rather than a direct toxicity of U. The oxidative stress response was investigated by measuring the transcription of selected pro- and anti-oxidative genes, anti-oxidative enzyme capacities and concentration and redox status of major anti-oxidative metabolites. Cd strongly up-regulated lipoxygenase (LOX1) and NADPH-oxidases (RBOHD or C in roots and leaves, respectively) whereas this was not found in the U-treated plants. For the anti-oxidative response related enzymes both Cd and U induced a decrease in Cu/Zn superoxide dismutases (CSD1,2) and a concomitant increase in Fe-SOD (FSD1). However the increase

  10. Oxidative stress response in Arabidopsis thaliana roots and leaves exposed to cadmium, uranium or a combination of both stressors

    Energy Technology Data Exchange (ETDEWEB)

    Horemans, N.; Saenen, E.; Vandenhove, H. [Belgian Nuclear Research Centre, SCK.CEN, Boeretang 200, 2400 Mol (Belgium); Hendrix, S.; Keunen, E.; Cuypers, A. [Hasselt University, Centre for Environmental Sciences, Agoralaan, Building D, 3590 Diepenbeek (Belgium)

    2014-07-01

    Nuclear energy production or NORM industry released low amounts of radioactive substances together with non-radioactive substances (e.g., heavy metals, organic chemicals) to the environment. As sessile organisms, plants are commonly exposed to a number of adverse conditions and therefore it is interesting to study the stress responses of plants induced by the single stressors as well as in a in a multi-pollution set-up. The aim of this study was to understand and predict fast induced oxidative stress responses in plants exposed to Cd and U or a combination of both stressors. Arabidopsis thaliana plants grown hydroponically for 18 days were exposed to a Cd (5 μM) or {sup 238}U (25 μM) or an equi-toxic mixture of Cd and {sup 238}U (2.5 μM + 12.5 μM) for 24 h. As expected both metals were taken up into the plants with Cd being more readily transported to the leaves than U. The root-to-shoot ratio was approximately 1,3 for Cd whereas it was above 3500 for U. For both U and Cd the root-to-shoot ratio was not affected under multiple exposure conditions used here. Notwithstanding the limited exposure time, leave and root fresh weight was already decreasing in U-treated plants. For Cd or Cd+U a decreasing but at this point not significant trend was visible. As U concentrations in the leaves were very low the decrease in leaf fresh weight is possibly due to signaling from the roots rather than a direct toxicity of U. The oxidative stress response was investigated by measuring the transcription of selected pro- and anti-oxidative genes, anti-oxidative enzyme capacities and concentration and redox status of major anti-oxidative metabolites. Cd strongly up-regulated lipoxygenase (LOX1) and NADPH-oxidases (RBOHD or C in roots and leaves, respectively) whereas this was not found in the U-treated plants. For the anti-oxidative response related enzymes both Cd and U induced a decrease in Cu/Zn superoxide dismutases (CSD1,2) and a concomitant increase in Fe-SOD (FSD1). However

  11. Analyzing Arabidopsis thaliana root proteome provides insights into the molecular bases of enantioselective imazethapyr toxicity

    Science.gov (United States)

    Qian, Haifeng; Lu, Haiping; Ding, Haiyan; Lavoie, Michel; Li, Yali; Liu, Weiping; Fu, Zhengwei

    2015-07-01

    Imazethapyr (IM) is a widely used chiral herbicide that inhibits the synthesis of branched-chain amino acids (BCAAs). IM is thought to exert its toxic effects on amino acid synthesis mainly through inhibition of acetolactate synthase activity, but little is known about the potential effects of IM on other key biochemical pathways. Here, we exposed the model plant Arabidospsis thaliana to trace S- and R-IM enantiomer concentrations and examined IM toxicity effects on the root proteome using iTRAQ. Conventional analyses of root carbohydrates, organic acids, and enzyme activities were also performed. We discovered several previously unknown key biochemical pathways targeted by IM in Arabidospsis. 1,322 and 987 proteins were differentially expressed in response to R- and S-IM treatments, respectively. Bioinformatics and physiological analyses suggested that IM reduced the BCAA tissue content not only by strongly suppressing BCAA synthesis but also by increasing BCAA catabolism. IM also affected sugar and starch metabolism, changed the composition of root cell walls, increased citrate production and exudation, and affected the microbial community structure of the rhizosphere. The present study shed new light on the multiple toxicity mechanisms of a selective herbicide on a model plant.

  12. Light regulation of the growth response in corn root gravitropism

    Science.gov (United States)

    Kelly, M. O.; Leopold, A. C.

    1992-01-01

    Roots of Merit variety corn (Zea mays L.) require red light for orthogravitropic curvature. Experiments were undertaken to identify the step in the pathway from gravity perception to asymmetric growth on which light may act. Red light was effective in inducing gravitropism whether it was supplied concomitant with or as long as 30 minutes after the gravity stimulus (GS). The presentation time was the same whether the GS was supplied in red light or in darkness. Red light given before the GS slightly enhanced the rate of curvature but had little effect on the lag time or on the final curvature. This enhancement was expanded by a delay between the red light pulse and the GS. These results indicate that gravity perception and at least the initial transduction steps proceed in the dark. Light may regulate the final growth (motor) phase of gravitropism. The time required for full expression of the light enhancement of curvature is consistent with its involvement in some light-stimulated biosynthetic event.

  13. Life-cycle chronic gamma exposure of Arabidopsis thaliana induces growth effects but no discernable effects on oxidative stress pathways.

    Science.gov (United States)

    Vandenhove, Hildegarde; Vanhoudt, Nathalie; Cuypers, Ann; van Hees, May; Wannijn, Jean; Horemans, Nele

    2010-09-01

    Arabidopsis thaliana was exposed to low-dose chronic gamma irradiation during a full life cycle (seed to seed) and several biological responses were investigated. Applied dose rates were 2336, 367 and 81 microGy h(-1). Following 24 days (inflorescence emergence), 34 days (approximately 50% of flowers open) and 54 days (silice ripening) exposure, plants were harvested and monitored for biometric parameters, capacities of enzymes involved in the antioxidative defence mechanisms (SOD, APOD, GLUR, GPOD, SPOD, CAT, ME), glutathione and ascorbate pool, lipid peroxidation products, altered gene expression of selected genes encoding for antioxidative enzymes or reactive oxygen species production, and DNA integrity. Root fresh weight was significantly reduced after gamma exposure compared to the control at all stages monitored but no significant differences in root weight for the different dose rates applied was observed. Leaf and stem fresh weight were significantly reduced at the highest irradiation level after 54 days exposure only. Also total plant fresh was significantly lower at silice riping and this for the highest and medium dose rate applied. The dose rate estimated to result in a 10% reduction in growth (EDR-10) ranged between 60 and 80 microGy h(-1). Germination of seeds from the gamma irradiated plants was not hampered. For several of the antioxidative defence enzymes studied, the enzyme capacity was generally stimulated towards flowering but generally no significant effect of dose rate on enzyme capacity was observed. Gene analysis revealed a significant transient and dose dependent change in expression of RBOHC indicating active reactive oxygen production induced by gamma irradiation. No effect of irradiation was observed on concentration or reduction state of the non-enzymatic antioxidants, ascorbate and glutathione. The level of lipid peroxidation products remained constant throughout the observation period and was not affected by dose rate. The comet assay

  14. Tree growth and management in Ugandan agroforestry systems: effects of root pruning on tree growth and crop yield.

    Science.gov (United States)

    Wajja-Musukwe, Tellie-Nelson; Wilson, Julia; Sprent, Janet I; Ong, Chin K; Deans, J Douglas; Okorio, John

    2008-02-01

    Tree root pruning is a potential tool for managing belowground competition when trees and crops are grown together in agroforestry systems. We investigated the effects of tree root pruning on shoot growth and root distribution of Alnus acuminata (H.B. & K.), Casuarina equisetifolia L., Grevillea robusta A. Cunn. ex R. Br., Maesopsis eminii Engl. and Markhamia lutea (Benth.) K. Schum. and on yield of adjacent crops in sub-humid Uganda. The trees were 3 years old at the commencement of the study, and most species were competing strongly with crops. Tree roots were pruned 41 months after planting by cutting and back-filling a trench to a depth of 0.3 m, at a distance of 0.3 m from the trees, on one side of the tree row. The trench was reopened and roots recut at 50 and 62 months after planting. We assessed the effects on tree growth and root distribution over a 3 year period, and crop yield after the third root pruning at 62 months. Overall, root pruning had only a slight effect on aboveground tree growth: height growth was unaffected and diameter growth was reduced by only 4%. A substantial amount of root regrowth was observed by 11 months after pruning. Tree species varied in the number and distribution of roots, and C. equisetifolia and M. lutea had considerably more roots per unit of trunk volume than the other species, especially in the surface soil layers. Casuarina equisetifolia and M. eminii were the tree species most competitive with crops and G. robusta and M. lutea the least competitive. Crop yield data provided strong evidence of the redistribution of root activity following root pruning, with competition increasing on the unpruned side of tree rows. Thus, one-sided root pruning will be useful in only a few circumstances. PMID:18055434

  15. A novel high efficiency, low maintenance, hydroponic system for synchronous growth and flowering of Arabidopsis thaliana

    OpenAIRE

    Bernier Georges; Kurtem Emile; Pieltain Alexandra; Havelange Andrée; Corbesier Laurent; Tocquin Pierre; Périlleux Claire

    2003-01-01

    Abstract Background Arabidopsis thaliana is now the model organism for genetic and molecular plant studies, but growing conditions may still impair the significance and reproducibility of the experimental strategies developed. Besides the use of phytotronic cabinets, controlling plant nutrition may be critical and could be achieved in hydroponics. The availability of such a system would also greatly facilitate studies dealing with root development. However, because of its small size and roset...

  16. A conserved KIN17 curved DNA-binding domain protein assembles with SQUAMOSA PROMOTER-BINDING PROTEIN-LIKE7 to adapt Arabidopsis growth and development to limiting copper availability.

    Science.gov (United States)

    Garcia-Molina, Antoni; Xing, Shuping; Huijser, Peter

    2014-02-01

    Proper copper (Cu) homeostasis is required by living organisms to maintain essential cellular functions. In the model plant Arabidopsis (Arabidopsis thaliana), the SQUAMOSA PROMOTER-BINDING PROTEIN-LIKE7 (SPL7) transcription factor participates in reprogramming global gene expression during Cu insufficiency in order to improve the metal uptake and prioritize its distribution to Cu proteins of major importance. As a consequence, spl7 null mutants show morphological and physiological disorders during Cu-limited growth, resulting in lower fresh weight, reduced root elongation, and chlorosis. On the other hand, the Arabidopsis KIN17 homolog belongs to a well-conserved family of essential eukaryotic nuclear proteins known to be stress activated and involved in DNA and possibly RNA metabolism in mammals. In the study presented here, we uncovered that Arabidopsis KIN17 participates in promoting the Cu deficiency response by means of a direct interaction with SPL7. Moreover, the double mutant kin17-1 spl7-2 displays an enhanced Cu-dependent phenotype involving growth arrest, oxidative stress, floral bud abortion, and pollen inviability. Taken together, the data presented here provide evidence for SPL7 and KIN17 protein interaction as a point of convergence in response to both Cu deficiency and oxidative stress. PMID:24335506

  17. Aluminium-induced ion transport in Arabidopsis: the relationship between Al tolerance and root ion flux.

    Science.gov (United States)

    Bose, Jayakumar; Babourina, Olga; Shabala, Sergey; Rengel, Zed

    2010-06-01

    Aluminium (Al) rhizotoxicity coincides with low pH; however, it is unclear whether plant tolerance to these two factors is controlled by the same mechanism. To address this question, the Al-resistant alr104 mutant, two Al-sensitive mutants (als3 and als5), and wild-type Arabidopsis thaliana were compared in long-term exposure (solution culture) and in short-term exposure experiments (H(+) and K(+) fluxes, rhizosphere pH, and plasma membrane potential, E(m)). Based on biomass accumulation, als5 and alr104 showed tolerance to low pH, whereas alr104 was tolerant to the combined low-pH/Al treatment. The sensitivity of the als5 and als3 mutants to the Al stress was similar. The Al-induced decrease in H(+) influx at the distal elongation zone (DEZ) and Al-induced H(+) efflux at the mature zone (MZ) were higher in the Al-sensitive mutants (als3 and als5) than in the wild type and the alr104 mutant. Under combined low-pH/Al treatment, alr104 and the wild type had depolarized plasma membranes for the entire 30 min measurement period, whereas in the Al-sensitive mutants (als3 and als5), initial depolarization to around -60 mV became hyperpolarization at -110 mV after 20 min. At the DEZ, the E(m) changes corresponded to the changes in K(+) flux: K(+) efflux was higher in alr104 and the wild type than in the als3 and als5 mutants. In conclusion, Al tolerance in the alr104 mutant correlated with E(m) depolarization, higher K(+) efflux, and higher H(+) influx, which led to a more alkaline rhizosphere under the combined low-pH/Al stress. Low-pH tolerance (als5) was linked to higher H(+) uptake under low-pH stress, which was abolished by Al exposure. PMID:20497972

  18. Fluorescence reports intact quantum dot uptake into roots and translocation to leaves of Arabidopsis thaliana and subsequent ingestion by insect herbivores.

    Science.gov (United States)

    Koo, Yeonjong; Wang, Jing; Zhang, Qingbo; Zhu, Huiguang; Chehab, E Wassim; Colvin, Vicki L; Alvarez, Pedro J J; Braam, Janet

    2015-01-01

    We explored the impact of quantum dot (QD) coat characteristics on NP stability, uptake, and translocation in Arabidopsis thaliana, and subsequent transfer to primary consumers, Trichoplusia ni (T. ni). Arabidopsis was exposed to CdSe/CdZnS QDs with three different coatings: Poly(acrylic acid-ethylene glycol) (PAA-EG), polyethylenimine (PEI) and poly(maleic anhydride-alt-1-octadecene)-poly(ethylene glycol) (PMAO-PEG), which are anionic, cationic, and relatively neutral, respectively. PAA-EG-coated QDs were relatively stable and taken up from a hydroponic medium through both Arabidopsis leaf petioles and roots, without apparent aggregation, and showed generally uniform distribution in leaves. In contrast, PEI- and PMAO-PEG-coated QDs displayed destabilization in the hydroponic medium, and generated particulate fluorescence plant tissues, suggesting aggregation. PAA-EG QDs moved faster than PEI QDs through leaf petioles; however, 8-fold more cadmium accumulated in PEI QD-treated leaves than in those exposed to PAA-EG QDs, possibly due to PEI QD dissolution and direct metal uptake. T. ni caterpillars that fed on Arabidopsis exposed to QDs had reduced performance, and QD fluorescence was detected in both T. ni bodies and frass, demonstrating trophic transfer of intact QDs from plants to insects. Overall, this paper demonstrates that QD coat properties influence plant nanoparticle uptake and translocation and can impact transfer to herbivores. PMID:25437125

  19. ARG1 and ARL2 contribute to gravity signal transduction in the statocytes of Arabidopsis thaliana roots and hypocotyls

    Science.gov (United States)

    Masson, Patrick; Harrison, Benjamin; Stanga, John; Otegui, Marisa; Sedbrook, John

    Gravity is an important cue that plant organs use to guide their growth. Each organ is characterized by a defined gravity set point angle that dictates its optimal orientation within the gravity field. Specialized cells, named statocytes, enable this directional growth response by perceiving gravity via the sedimentation of, and/or tension/pressure exerted by, starch-filled plastids within their cytoplasm. Located in the columella region of the cap in roots and in the endodermis of hypocotyls and stems, these cells modulate the lateral transport of auxin across the corresponding organ in a gravistimulus-dependent manner. Upon plant reorientation within the gravity field, a gravity signal transduction pathway is activated within those cells, which in roots leads to a relocalization of the PIN3 auxin efflux carrier toward the lower membrane and an alkalinization of the cytoplasm. In turn, these events appear to promote a lateral transport of auxin toward the bottom side of the stimulated organ, which promotes a curvature. We previously uncovered ARG1 and ARL2 as essential contributors to these cellular processes. Mutations in these genes result in altered root and hypocotyl gravitropism. In roots, this abnormal growth behavior is associated with a lack of PIN3 relocalization within the statocytes and an absence of preferential downward auxin transport upon gravistimulation. These two genes encode paralogous J-domain proteins that are associated with the plasma membrane and other membranes of the vesicular trafficking pathway, and appear to modulate protein trafficking within the statocytes. An analysis of the root gravitropic phenotypes associated with different double mutant configurations affecting ARG1, ARL2 and PIN3 suggest that all three proteins function in a common gravity-signaling pathway. Surprisingly, when a mutation that affects starch biosynthesis (pgm) is introgressed into an arg1-2 mutant, the gravitropic defects are dramatically enhanced relative to

  20. Root cooling strongly affects diel leaf growth dynamics, water and carbohydrate relations in Ricinus communis.

    Science.gov (United States)

    Poiré, Richard; Schneider, Heike; Thorpe, Michael R; Kuhn, Arnd J; Schurr, Ulrich; Walter, Achim

    2010-03-01

    In laboratory and greenhouse experiments with potted plants, shoots and roots are exposed to temperature regimes throughout a 24 h (diel) cycle that can differ strongly from the regime under which these plants have evolved. In the field, roots are often exposed to lower temperatures than shoots. When the root-zone temperature in Ricinus communis was decreased below a threshold value, leaf growth occurred preferentially at night and was strongly inhibited during the day. Overall, leaf expansion, shoot biomass growth, root elongation and ramification decreased rapidly, carbon fluxes from shoot to root were diminished and carbohydrate contents of both root and shoot increased. Further, transpiration rate was not affected, yet hydrostatic tensions in shoot xylem increased. When root temperature was increased again, xylem tension reduced, leaf growth recovered rapidly, carbon fluxes from shoot to root increased, and carbohydrate pools were depleted. We hypothesize that the decreased uptake of water in cool roots diminishes the growth potential of the entire plant - especially diurnally, when the growing leaf loses water via transpiration. As a consequence, leaf growth and metabolite concentrations can vary enormously, depending on root-zone temperature and its heterogeneity inside pots. PMID:19968824

  1. Distribution of G-actin is Related to Root Hair Growth of Wheat

    OpenAIRE

    He, Xue; Liu, Yi-Min; Wang, Wei; LI Yan

    2006-01-01

    • Background and Aims Actin distribution in root hair tips is a controversial topic. Although the relationship between Ca2+ gradient and actin dynamics in plant tip-growth has been a focus of study, there is still little direct evidence on the exact relationship in root hair tip-growth.

  2. A comparison of two models to evaluate soil compaction effects on corn root growth

    Science.gov (United States)

    Several complex interactions among soil physical properties influence root growth of common crops. Models are used to combine limitations of temperature, aeration, water availability and soil strength to determine the zonal suitability for root growth. Two models are compared in this study, the Jone...

  3. Beneficial Bacteria Isolated from Grapevine Inner Tissues Shape Arabidopsis thaliana Roots

    OpenAIRE

    Enrico Baldan; Sebastiano Nigris; Chiara Romualdi; Stefano D'Alessandro; Anna Clocchiatti; Michela Zottini; Piergiorgio Stevanato; Andrea Squartini; Barbara Baldan

    2015-01-01

    We investigated the potential plant growth-promoting traits of 377 culturable endophytic bacteria, isolated from Vitis vinifera cv. Glera, as good biofertilizer candidates in vineyard management. Endophyte ability in promoting plant growth was assessed in vitro by testing ammonia production, phosphate solubilization, indole-3-acetic acid (IAA) and IAA-like molecule biosynthesis, siderophore and lytic enzyme secretion. Many of the isolates were able to mobilize phosphate (33%), release ammoniu...

  4. The glucosinolate breakdown product indole-3-carbinol acts as an auxin antagonist in roots of Arabidopsis thaliana.

    Science.gov (United States)

    Katz, Ella; Nisani, Sophia; Yadav, Brijesh S; Woldemariam, Melkamu G; Shai, Ben; Obolski, Uri; Ehrlich, Marcelo; Shani, Eilon; Jander, Georg; Chamovitz, Daniel A

    2015-05-01

    The glucosinolate breakdown product indole-3-carbinol functions in cruciferous vegetables as a protective agent against foraging insects. While the toxic and deterrent effects of glucosinolate breakdown on herbivores and pathogens have been studied extensively, the secondary responses that are induced in the plant by indole-3-carbinol remain relatively uninvestigated. Here we examined the hypothesis that indole-3-carbinol plays a role in influencing plant growth and development by manipulating auxin signaling. We show that indole-3-carbinol rapidly and reversibly inhibits root elongation in a dose-dependent manner, and that this inhibition is accompanied by a loss of auxin activity in the root meristem. A direct interaction between indole-3-carbinol and the auxin perception machinery was suggested, as application of indole-3-carbinol rescues auxin-induced root phenotypes. In vitro and yeast-based protein interaction studies showed that indole-3-carbinol perturbs the auxin-dependent interaction of Transport Inhibitor Response (TIR1) with auxin/3-indoleacetic acid (Aux/IAAs) proteins, further supporting the possibility that indole-3-carbinol acts as an auxin antagonist. The results indicate that chemicals whose production is induced by herbivory, such as indole-3-carbinol, function not only to repel herbivores, but also as signaling molecules that directly compete with auxin to fine tune plant growth and development. PMID:25758811

  5. A P-Loop NTPase Regulates Quiescent Center Cell Division and Distal Stem Cell Identity through the Regulation of ROS Homeostasis in Arabidopsis Root.

    Science.gov (United States)

    Yu, Qianqian; Tian, Huiyu; Yue, Kun; Liu, Jiajia; Zhang, Bing; Li, Xugang; Ding, Zhaojun

    2016-09-01

    Reactive oxygen species (ROS) are recognized as important regulators of cell division and differentiation. The Arabidopsis thaliana P-loop NTPase encoded by APP1 affects root stem cell niche identity through its control of local ROS homeostasis. The disruption of APP1 is accompanied by a reduction in ROS level, a rise in the rate of cell division in the quiescent center (QC) and the promotion of root distal stem cell (DSC) differentiation. Both the higher level of ROS induced in the app1 mutant by exposure to methyl viologen (MV), and treatment with hydrogen peroxide (H2O2) rescued the mutant phenotype, implying that both the increased rate of cell division in the QC and the enhancement in root DSC differentiation can be attributed to a low level of ROS. APP1 is expressed in the root apical meristem cell mitochondria, and its product is associated with ATP hydrolase activity. The key transcription factors, which are defining root distal stem niche, such as SCARECROW (SCR) and SHORT ROOT (SHR) are both significantly down-regulated at both the transcriptional and protein level in the app1 mutant, indicating that SHR and SCR are important downstream targets of APP1-regulated ROS signaling to control the identity of root QC and DSCs. PMID:27583367

  6. The signal transducer NPH3 integrates the phototropin1 photosensor with PIN2-based polar auxin transport in Arabidopsis root phototropism.

    Science.gov (United States)

    Wan, Yinglang; Jasik, Jan; Wang, Li; Hao, Huaiqing; Volkmann, Dieter; Menzel, Diedrik; Mancuso, Stefano; Baluška, František; Lin, Jinxing

    2012-02-01

    Under blue light (BL) illumination, Arabidopsis thaliana roots grow away from the light source, showing a negative phototropic response. However, the mechanism of root phototropism is still unclear. Using a noninvasive microelectrode system, we showed that the BL sensor phototropin1 (phot1), the signal transducer NONPHOTOTROPIC HYPOCOTYL3 (NPH3), and the auxin efflux transporter PIN2 were essential for BL-induced auxin flux in the root apex transition zone. We also found that PIN2-green fluorescent protein (GFP) localized to vacuole-like compartments (VLCs) in dark-grown root epidermal and cortical cells, and phot1/NPH3 mediated a BL-initiated pathway that caused PIN2 redistribution to the plasma membrane. When dark-grown roots were exposed to brefeldin A (BFA), PIN2-GFP remained in VLCs in darkness, and BL caused PIN2-GFP disappearance from VLCs and induced PIN2-GFP-FM4-64 colocalization within enlarged compartments. In the nph3 mutant, both dark and BL BFA treatments caused the disappearance of PIN2-GFP from VLCs. However, in the phot1 mutant, PIN2-GFP remained within VLCs under both dark and BL BFA treatments, suggesting that phot1 and NPH3 play different roles in PIN2 localization. In conclusion, BL-induced root phototropism is based on the phot1/NPH3 signaling pathway, which stimulates the shootward auxin flux by modifying the subcellular targeting of PIN2 in the root apex transition zone. PMID:22374399

  7. Growth and changes of endogenous hormones of mulberry roots in a simulated rocky desertification area.

    Science.gov (United States)

    Feng, Dalan; Huang, Xiaohui; Liu, Yun; Willison, J H Martin

    2016-06-01

    We studied the growth of roots of white mulberry (Morus alba) trees in response to different water and nutrient conditions in sets of three or five containers connected via small pipes and arranged so as to simulate the heterogeneous soil conditions associated with rocky desertification. The experiment was conducted to improve understanding of the adaptation of M. alba to this stressful environment. The trees were grown for a year under constant water and nutrient conditions in the soils within each container of any set of containers. Differences in root activity and endogenous hormones within root tips were measured at the end of the experiment. We compared four treatment groups: H (variable moisture among containers), F (variable nutrients among containers), HF (both moisture and nutrients varied among containers), and CK (non-varied control). Results showed the following: (1) Mulberry roots showed obvious hydrotropic and chemotropic growth patterns, but chemotropism did not occur in the condition of water shortage. (2) Measurement of growth indices (root surface area, total root length, number of root tips, root biomass) showed that growth status was best in group HF once the roots were able to access containers with sufficient water and nutrients, followed by group H. The indices were significantly poorer in groups F and CK. (3) The content of auxin, cytokinin, and gibberellins in roots under soil drought conditions were lower than under wetter soil conditions. In contrast, abscisic acid content and root activity were higher under soil drought conditions than under wetter soil conditions. The results indicated that water is the key factor restricting growth of white mulberry trees in areas of rocky desertification but that the trees adjust endogenous hormones in their roots to promote tropic growth and obtain sufficient moisture and nutrients over the long term. Moreover, under long-term drought stress conditions, mulberry trees retained high root activity

  8. Activation of NADPH-recycling systems in leaves and roots of Arabidopsis thaliana under arsenic-induced stress conditions is accelerated by knock-out of Nudix hydrolase 19 (AtNUDX19) gene.

    Science.gov (United States)

    Corpas, Francisco J; Aguayo-Trinidad, Simeón; Ogawa, Takahisa; Yoshimura, Kazuya; Shigeoka, Shigeru

    2016-03-15

    NADPH is an important cofactor in cell growth, proliferation and detoxification. Arabidopsis thaliana Nudix hydrolase 19 (AtNUDX19) belongs to a family of proteins defined by the conserved amino-acid sequence GX5-EX7REUXEEXGU which has the capacity to hydrolyze NADPH as a physiological substrate in vivo. Given the importance of NADPH in the cellular redox homeostasis of plants, the present study compares the responses of the main NADPH-recycling systems including NADP-isocitrate dehydrogenase (ICDH), glucose-6-phosphate dehydrogenase (G6PDH), 6-phosphogluconate dehydrogenase (6PGDH) and NADP-malic enzyme (ME) in the leaves and roots of Arabidopsis wild-type (Wt) and knock-out (KO) AtNUDX19 mutant (Atnudx19) plants under physiological and arsenic-induced stress conditions. Two major features were observed in the behavior of the main NADPH-recycling systems: (i) under optimal conditions in both organs, the levels of these activities were higher in nudx19 mutants than in Wt plants; and, (ii) under 500μM AsV conditions, these activities increase, especially in nudx19 mutant plants. Moreover, G6PDH activity in roots was the most affected enzyme in both Wt and nudx19 mutant plants, with a 4.6-fold and 5.0-fold increase, respectively. In summary, the data reveals a connection between the absence of chloroplastic AtNUDX19 and the rise in all NADP-dehydrogenase activities under physiological and arsenic-induced stress conditions, particularly in roots. This suggests that AtNUDX19 could be a key factor in modulating the NADPH pool in plants and consequently in redox homeostasis. PMID:26878367

  9. Wiring a plant: genetic networks for phloem formation in Arabidopsis thaliana roots.

    Science.gov (United States)

    Rodriguez-Villalon, Antia

    2016-04-01

    45 I. 45 II. 46 III. 46 IV. 47 V. 48 VI. 48 49 References 49 SUMMARY: In plants, phloem conduits form a specialized vascular network mediating the exchange of nutrients and signaling molecules between distantly separated organs. To become effective transport elements, protophloem cells undergo a rather unique, differentiation program that involves nucleus degradation, organelle rearrangement and cell wall thickening. Yet, protophloem sieve elements remain alive because their essential metabolic functions are supported by their neighboring companion cells. In spite of the importance of the phloem, the molecular mechanisms orchestrating protophloem specification and differentiation remain still poorly understood. In this review, I provide a summary of recent discoveries regarding morphogenetic events that determine phloem formation, and also a discussion of the systemic effects on root architecture derived from impaired protophloem differentiation programs. PMID:26171671

  10. Modeling the hydraulics of root growth in three dimensions with phloem water sources.

    Science.gov (United States)

    Wiegers, Brandy S; Cheer, Angela Y; Silk, Wendy K

    2009-08-01

    Primary growth is characterized by cell expansion facilitated by water uptake generating hydrostatic (turgor) pressure to inflate the cell, stretching the rigid cell walls. The multiple source theory of root growth hypothesizes that root growth involves transport of water both from the soil surrounding the growth zone and from the mature tissue higher in the root via phloem and protophloem. Here, protophloem water sources are used as boundary conditions in a classical, three-dimensional model of growth-sustaining water potentials in primary roots. The model predicts small radial gradients in water potential, with a significant longitudinal gradient. The results improve the agreement of theory with empirical studies for water potential in the primary growth zone of roots of maize (Zea mays). A sensitivity analysis quantifies the functional importance of apical phloem differentiation in permitting growth and reveals that the presence of phloem water sources makes the growth-sustaining water relations of the root relatively insensitive to changes in root radius and hydraulic conductivity. Adaptation to drought and other environmental stresses is predicted to involve more apical differentiation of phloem and/or higher phloem delivery rates to the growth zone. PMID:19542299

  11. Overexpression of Arabidopsis NLP7 improves plant growth under both nitrogen-limiting and -sufficient conditions by enhancing nitrogen and carbon assimilation.

    Science.gov (United States)

    Yu, Lin-Hui; Wu, Jie; Tang, Hui; Yuan, Yang; Wang, Shi-Mei; Wang, Yu-Ping; Zhu, Qi-Sheng; Li, Shi-Gui; Xiang, Cheng-Bin

    2016-01-01

    Nitrogen is essential for plant survival and growth. Excessive application of nitrogenous fertilizer has generated serious environment pollution and increased production cost in agriculture. To deal with this problem, tremendous efforts have been invested worldwide to increase the nitrogen use ability of crops. However, only limited success has been achieved to date. Here we report that NLP7 (NIN-LIKE PROTEIN 7) is a potential candidate to improve plant nitrogen use ability. When overexpressed in Arabidopsis, NLP7 increases plant biomass under both nitrogen-poor and -rich conditions with better-developed root system and reduced shoot/root ratio. NLP7-overexpressing plants show a significant increase in key nitrogen metabolites, nitrogen uptake, total nitrogen content, and expression levels of genes involved in nitrogen assimilation and signalling. More importantly, overexpression of NLP7 also enhances photosynthesis rate and carbon assimilation, whereas knockout of NLP7 impaired both nitrogen and carbon assimilation. In addition, NLP7 improves plant growth and nitrogen use in transgenic tobacco (Nicotiana tabacum). Our results demonstrate that NLP7 significantly improves plant growth under both nitrogen-poor and -rich conditions by coordinately enhancing nitrogen and carbon assimilation and sheds light on crop improvement. PMID:27293103

  12. Root exudate-induced alterations in Bacillus cereus cell wall contribute to root colonization and plant growth promotion.

    Directory of Open Access Journals (Sweden)

    Swarnalee Dutta

    Full Text Available The outcome of an interaction between plant growth promoting rhizobacteria and plants may depend on the chemical composition of root exudates (REs. We report the colonization of tobacco, and not groundnut, roots by a non-rhizospheric Bacillus cereus (MTCC 430. There was a differential alteration in the cell wall components of B. cereus in response to the REs from tobacco and groundnut. Attenuated total reflectance infrared spectroscopy revealed a split in amide I region of B. cereus cells exposed to tobacco-root exudates (TRE, compared to those exposed to groundnut-root exudates (GRE. In addition, changes in exopolysaccharides and lipid-packing were observed in B. cereus grown in TRE-amended minimal media that were not detectable in GRE-amended media. Cell-wall proteome analyses revealed upregulation of oxidative stress-related alkyl hydroperoxide reductase, and DNA-protecting protein chain (Dlp-2, in response to GRE and TRE, respectively. Metabolism-related enzymes like 2-amino-3-ketobutyrate coenzyme A ligase and 2-methylcitrate dehydratase and a 60 kDa chaperonin were up-regulated in response to TRE and GRE. In response to B. cereus, the plant roots altered their exudate-chemodiversity with respect to carbohydrates, organic acids, alkanes, and polyols. TRE-induced changes in surface components of B. cereus may contribute to successful root colonization and subsequent plant growth promotion.

  13. On the role of a Lipid-Transfer Protein. Arabidopsis ltp3 mutant is compromised in germination and seedling growth.

    Science.gov (United States)

    Pagnussat, Luciana A; Oyarburo, Natalia; Cimmino, Carlos; Pinedo, Marcela L; de la Canal, Laura

    2015-01-01

    Plant Lipid-Transfer Proteins (LTPs) exhibit the ability to reversibly bind/transport lipids in vitro. LTPs have been involved in diverse physiological processes but conclusive evidence on their role has only been presented for a few members, none of them related to seed physiology. Arabidopsis seeds rely on storage oil breakdown to supply carbon skeletons and energy for seedling growth. Here, Arabidopsis ltp3 mutant was analyzed for its ability to germinate and for seedling establishment. Ltp3 showed delayed germination and reduced germination frequency. Seedling growth appeared reduced in the mutant but this growth restriction was rescued by the addition of an exogenous carbon supply, suggesting a defective oil mobilization. Lipid breakdown analysis during seedling growth revealed a differential profile in the mutant compared to the wild type. The involvement of LTP3 in germination and seedling growth and its relationship with the lipid transfer ability of this protein is discussed. PMID:26479260

  14. Change of water use efficiency and its relation with root system growth in wheat evolution

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Raising crop water use efficiency (WUE) is the physiological basis to implement crop high efficiently using water. The present soil column and field experiments are designed to investigate the change of wheat WUE (Triticum aestivum L.) at whole plant level and root system growth in evolution and the relationship between WUE and its root system growth using 10 wheat evolution genotypes with different ploidy chromosomes sets. Results show that in wheat evolution from 2n→6n, WUE at whole plant level increases with the increase of ploidy chromosomes, and root system growth (root weight, root length) and root/shoot ratio of wheat decrease with the increase of ploidy chromosomes under dry and irrigated conditions. WUE is negatively correlated with root weight and root/shoot ratio of wheat in evolution, significantly. Root system growth has an adverse redundancy for WUE in wheat evolution, and the root redundancy reduces with the increase of ploidy chromosomes, which result in the increase of wheat WUE at whole plant level.

  15. Intercropping effect on root growth and nitrogen uptake at different nitrogen levels

    DEFF Research Database (Denmark)

    Ramirez-Garcia, Javier; Martens, Helle Juel; Quemada, Miguel;

    2015-01-01

    Aims Intercropping legumes and non-legumes may affect the root growth of both components in the mixture, and the non-legume is known to be strongly favored by increasing nitrogen (N) supply. The knowledge of how root systems affect the growth of the individual species is useful for understanding...... the interactions in intercrops as well as for planning cover cropping strategies. The aim of this work was (i) to determine if different levels of N in the topsoil influence root depth (RD) and intensity of barley and vetch as sole crops or as an intercropped mixture and (ii) to test if the choice of...... a mixture or the N availability in the topsoil will influence the N uptake by deep roots.Methods In this study, we combined rhizotron studies with root extraction and species identification by microscopy with studies of growth, N uptake and 15N uptake from deeper soil layers, for studying the root...

  16. Indole-3-butyric acid synthesis in ecotypes and mutants of Arabidopsis thaliana under different growth conditions.

    Science.gov (United States)

    Ludwig-Müller, Jutta

    2007-01-01

    Although IBA is a naturally occurring auxin, its role in plant development is still under debate. In this study a set of Arabidopsis mutants was used to analyze the biosynthesis of IBA in vitro. The mutants chosen for this study can be classified as: (1) involvement in auxin metabolism, transport or synthesis (amt1, aux1, ilr1, nit1, rib1, sur1, trp1-100); (2) other hormones possibly involved in the regulation of IBA synthesis (aba1, aba3, eto2, fae1, hls1, jar1); (3) photomorphogenesis (det1, det2, det3); and (4) root architecture (cob1, cob2, scr1). In addition, two transgenic lines overexpressing the IAA glucose synthase (iaglu) gene from maize were analyzed. The ecotypes No-0 and Wassilewskija showed the highest IBA synthetase activity under control conditions, followed by Columbia, Enkheim and Landsberg erecta. In the mutant lines IBA synthetase activity differed in most cases from the wild type, however no particular pattern of up- or down-regulation, which could be correlated to their possible function, was found. For rib1 mutant seedlings it was tested whether reduced IBA synthetase activity correlates with the endogenous IBA levels. Free IBA differed only depending on the culture conditions, but gave no clear correlation with IBA synthetase activity compared to the wild type. Since drought and osmotic stress as well as abscisic acid (ABA) application enhanced IBA synthesis in maize, it was tested whether IBA synthetase from Arabidopsis is also inducible by drought stress conditions. This was confirmed for the two ecotypes Col and Ler which showed different IBA synthetase activity when cultivated with various degrees of drought stress. IBA synthetase was also determined in photomorphogenic mutants under different light regimes. Induction of IBA synthetase in det1 and det3 plants was found under short day plus a red light pulse or in the dark, respectively. The results are discussed with respect to the functions of the mutated genes. PMID:16325963

  17. The influence of calcium and pH on growth in primary roots of Zea mays

    Science.gov (United States)

    Hasenstein, K. H.; Evans, M. L.

    1988-01-01

    We investigated the interaction of Ca2+ and pH on root elongation in Zea mays L. cv. B73 x Missouri 17 and cv. Merit. Seedlings were raised to contain high levels of Ca2+ (HC, imbibed and raised in 10 mM CaCl2) or low levels of Ca2+ (LC, imbibed and raised in distilled water). In HC roots, lowering the pH (5 mM MES/Tris) from 6.5 to 4.5 resulted in strong, long-lasting growth promotion. Surprisingly, increasing the pH from 6.5 to 8.5 also resulted in strong growth promotion. In LC roots acidification of the medium (pH 6.5 to 4.5) resulted in transient growth stimulation followed by a gradual decline in the growth rate toward zero. Exposure of LC roots to high pH (pH shift from 6.5 to 8.5) also promoted growth. Addition of EGTA resulted in strong growth promotion in both LC and HC roots. The ability of EGTA to stimulate growth appeared not to be related to H+ release from EGTA upon Ca2+ chelation since, 1) LC roots showed a strong and prolonged response to EGTA, but only a transient response to acid pH, and 2) promotion of growth by EGTA was observed in strongly buffered solutions. We also examined the pH dependence of the release of 45Ca2+ from roots of 3-day-old seedlings grown from grains imbibed in 45Ca2+. Release of 45Ca2+ from the root into agar blocks placed on the root surface was greater the more acidic the pH of the blocks. The results indicate that Ca2+ may be necessary for the acid growth response in roots.

  18. Effects of some plant growth promoting rhizobacteria (PGPR on rooting of grapevine rootstocks

    Directory of Open Access Journals (Sweden)

    Cafer Köse

    2013-12-01

    Full Text Available In this study. effects of topical applications of two plant growth promoting rhizobacteria (PGPR strains and their combination (Bacillus BA16, OSU142 and BA16+OSU142 on the rooting of 41B and Rupestris du Lot rootstocks were investigated. The results showed that none of the bacterial strains have significant effects on success rate at 41B and Rupestris du Lot alone, but BA16+0SU142 combination significantly increased the rooting rate and rooting degree of 41B, and decreased the rooting rate and rooting degree of Rupestris du Lot compared with control. In addition, none of the applications had significant effects in number, length and weight of roots on cuttings of both 41B and Rupestris du Lot. Our results suggest that PGPR may have a great potential to stimulate the rooting of hardwood cuttings of grapevine rootstocks, with low rooting capability.

  19. TOR Signaling Promotes Accumulation of BZR1 to Balance Growth with Carbon Availability in Arabidopsis.

    Science.gov (United States)

    Zhang, Zhenzhen; Zhu, Jia-Ying; Roh, Jeehee; Marchive, Chloé; Kim, Seong-Ki; Meyer, Christian; Sun, Yu; Wang, Wenfei; Wang, Zhi-Yong

    2016-07-25

    For maintenance of cellular homeostasis, the actions of growth-promoting hormones must be attenuated when nutrient and energy become limiting. The molecular mechanisms that coordinate hormone-dependent growth responses with nutrient availability remain poorly understood in plants [1, 2]. The target of rapamycin (TOR) kinase is an evolutionarily conserved master regulator that integrates nutrient and energy signaling to regulate growth and homeostasis in both animals and plants [3-7]. Here, we show that sugar signaling through TOR controls the accumulation of the brassinosteroid (BR)-signaling transcription factor BZR1, which is essential for growth promotion by multiple hormonal and environmental signals [8-11]. Starvation, caused by shifting of light-grown Arabidopsis seedlings into darkness, as well as inhibition of TOR by inducible RNAi, led to plant growth arrest and reduced expression of BR-responsive genes. The growth arrest caused by TOR inactivation was partially recovered by BR treatment and the gain-of-function mutation bzr1-1D, which causes accumulation of active forms of BZR1 [12]. Exogenous sugar promoted BZR1 accumulation and seedling growth, but such sugar effects were largely abolished by inactivation of TOR, whereas the effect of TOR inactivation on BZR1 degradation is abolished by inhibition of autophagy and by the bzr1-1D mutation. These results indicate that cellular starvation leads sequentially to TOR inactivation, autophagy, and BZR1 degradation. Such regulation of BZR1 accumulation by glucose-TOR signaling allows carbon availability to control the growth promotion hormonal programs, ensuring supply-demand balance in plant growth. PMID:27345161

  20. Vigorous Root Growth Is a Better Indicator of Early Nutrient Uptake than Root Hair Traits in Spring Wheat Grown under Low Fertility

    OpenAIRE

    Wang, Yaosheng; Thorup-Kristensen, Kristian; Jensen, Lars Stoumann; Magid, Jakob

    2016-01-01

    A number of root and root hair traits have been proposed as important for nutrient acquisition. However, there is still a need for knowledge on which traits are most important in determining macro- and micronutrient uptake at low soil fertility. This study investigated the variations in root growth vigor and root hair length (RHL) and density (RHD) among spring wheat genotypes and their relationship to nutrient concentrations and uptake during early growth. Six spring wheat genotypes were gro...

  1. Tracking soil structural changes during root growth with sequential X-Ray CT scanning

    Science.gov (United States)

    Schmidt, Sonja; Bengough, Glyn; Hallett, Paul

    2014-05-01

    Crop productivity is highly dependent on a good supply of water and nutrients. With increasing demand for food and variable water regimes due to climate change, it is important to get a better understanding on the processes involved in water and nutrient uptake by roots. Changes in soil structure affect water and nutrient availabilities for plants. It is known that roots change their environment during growth but little is known on how soil structural properties change as roots penetrate soils. More detailed information on root growth induced changes in the rhizosphere will help us to model water and nutrient uptake by plants. The objective of this study was to measure directly how soil structure changes in close proximity to the root as a seedling root penetrates through the soil. 3D volumetric images of maize root growth during six hours were obtained using X-ray microtomography at a resolution of 21 μm. Roots were grown in soils of two different compaction levels (50 kPa and 200 kPa uniaxial load) and matric potentials (10 kPa and 100 kPa). Changes in porosity, pore connectivity and root-soil contact were determined from 2D cross sections for each time step. The 2D cross sections were chosen at 4 different positions in the sample, and each section was divided into sections of 64 voxels (1.3 mm2) to determine changes in porosity and connectivity with distance from the root. Soil movement caused by root growth was quantified from 2D cross sections at different positions along the sample using Particle image velocimetry (PIV). Changes in soil structure during root growth were observed. Porosity in close proximity to the root decreased whereas root-soil contact increased with time. The PIV showed a radial deformation of the soil. Greatest deformation was found close to the root. Some aggregates fractured during root growth whereas others were pushed into the pore space. These data on the changes in soil structure will help us to predict water and nutrient

  2. Growth Rings of Roots in Perennial Forbs in Duolun Grassland, Inner Mongolia, China

    Institute of Scientific and Technical Information of China (English)

    Yong-Bo Liu; Qi-Bin Zhang

    2007-01-01

    Annual growth rings of roots in perennial forbs have been used in studies of climate change and the ecology of grasslands. However, little has been done in this aspect of research in China. In this study, we report the characteristics of growth rings in the main roots of 13 herb species sampled in Duolun of the Inner Mongolia grassland in northern China. The results show that around two thirds of the species possess clearly demarcated annual rings in the root xylem. Some species of the same genera show different patterns in anatomical structure of the root xylem. Standardized annual ring widths of three species, Potentilla anserine L., Cymbaria dahurica L. and Lespedeza daurica (Laxm.) Schindl., show a common linear trend, indicating a continued favorable growth condition in the sampling sites. Our results provide evidence that growth rings in roots of some perennial forbs in the Inner Mongolia grassland can serve as a new and useful indicator of past changes in the grassland environment.

  3. Enhancement of chlorogenic acid production in hairy roots of Platycodon grandiflorum by over-expression of an Arabidopsis thaliana transcription factor AtPAP1.

    Science.gov (United States)

    Tuan, Pham Anh; Kwon, Do Yeon; Lee, Sanghyun; Arasu, Mariadhas Valan; Al-Dhabi, Naif Abdullah; Park, Nam Il; Park, Sang Un

    2014-01-01

    To improve the production of chlorogenic acid (CGA) in hairy roots of Platycodon grandiflorum, we induced over-expression of Arabidopsis thaliana transcription factor production of anthocyanin pigment (AtPAP1) using an Agrobacterium rhizogenes-mediated transformation system. Twelve hairy root lines showing over-expression of AtPAP1 were generated. In order to investigate the regulation of AtPAP1 on the activities of CGA biosynthetic genes, the expression levels of seven P. grandiflorum CGA biosynthetic genes were analyzed in the hairy root line that had the greatest accumulation of AtPAP1 transcript, OxPAP1-1. The introduction of AtPAP1 increased the mRNA levels of all examined CGA biosynthetic genes and resulted in a 900% up-regulation of CGA accumulation in OxPAP1-1 hairy roots relative to controls. This suggests that P. grandiflorum hairy roots that over-express the AtPAP1 gene are a potential alternative source of roots for the production of CGA. PMID:25153629

  4. Enhancement of Chlorogenic Acid Production in Hairy Roots of Platycodon grandiflorum by Over-Expression of An Arabidopsis thaliana Transcription Factor AtPAP1

    Directory of Open Access Journals (Sweden)

    Pham Anh Tuan

    2014-08-01

    Full Text Available To improve the production of chlorogenic acid (CGA in hairy roots of Platycodon grandiflorum, we induced over-expression of Arabidopsis thaliana transcription factor production of anthocyanin pigment (AtPAP1 using an Agrobacterium rhizogenes-mediated transformation system. Twelve hairy root lines showing over-expression of AtPAP1 were generated. In order to investigate the regulation of AtPAP1 on the activities of CGA biosynthetic genes, the expression levels of seven P. grandiflorum CGA biosynthetic genes were analyzed in the hairy root line that had the greatest accumulation of AtPAP1 transcript, OxPAP1-1. The introduction of AtPAP1 increased the mRNA levels of all examined CGA biosynthetic genes and resulted in a 900% up-regulation of CGA accumulation in OxPAP1-1 hairy roots relative to controls. This suggests that P. grandiflorum hairy roots that over-express the AtPAP1 gene are a potential alternative source of roots for the production of CGA.

  5. Spatial Regulation of Root Growth: Placing the Plant TOR Pathway in a Developmental Perspective

    OpenAIRE

    2015-01-01

    Plant cells contain specialized structures, such as a cell wall and a large vacuole, which play a major role in cell growth. Roots follow an organized pattern of development, making them the organs of choice for studying the spatio-temporal regulation of cell proliferation and growth in plants. During root growth, cells originate from the initials surrounding the quiescent center, proliferate in the division zone of the meristem, and then increase in length in the elongation zone, reaching th...

  6. Effect of fast neutrons and gamma radiation on seedling and root growth of barley varieties

    International Nuclear Information System (INIS)

    Seven varieties of barley were irradiated with 10-80 krad of gamma rays and 0.3-1.2 krad of fast neutrons. Their radiosensitivity was compared on the basis of 50% reduction in seedling and root growth. The RBE (ratio: gamma/neutron, 50% growth reduction dose) for roots was twice as high as for seedling growth reduction. (author). 3 refs, 2 figs, 1 tab

  7. Function and regulation of transcription factors involved in root apical meristem and stem cell maintenance

    OpenAIRE

    Drisch, Rebecca C.; Stahl, Yvonne

    2015-01-01

    Plant roots are essential for overall plant development, growth, and performance by providing anchorage in the soil and uptake of nutrients and water. The primary root of higher plants derives from a group of pluripotent, mitotically active stem cells residing in the root apical meristem (RAM) which provides the basis for growth, development, and regeneration of the root. The stem cells in the Arabidopsis thaliana RAM are surrounding the quiescent center (QC), which consists of a group of rar...

  8. Non-targeted profiling of semi-polar metabolites in Arabidopsis root exudates uncovers a role for coumarin secretion and lignification during the local response to phosphate limitation.

    Science.gov (United States)

    Ziegler, Jörg; Schmidt, Stephan; Chutia, Ranju; Müller, Jens; Böttcher, Christoph; Strehmel, Nadine; Scheel, Dierk; Abel, Steffen

    2016-03-01

    Plants have evolved two major strategies to cope with phosphate (Pi) limitation. The systemic response, mainly comprising increased Pi uptake and metabolic adjustments for more efficient Pi use, and the local response, enabling plants to explore Pi-rich soil patches by reorganization of the root system architecture. Unlike previous reports, this study focused on root exudation controlled by the local response to Pi deficiency. To approach this, a hydroponic system separating the local and systemic responses was developed. Arabidopsis thaliana genotypes exhibiting distinct sensitivities to Pi deficiency could be clearly distinguished by their root exudate composition as determined by non-targeted reversed-phase ultraperformance liquid chromatography electrospray ionization quadrupole-time-of-flight mass spectrometry metabolite profiling. Compared with wild-type plants or insensitive low phosphate root 1 and 2 (lpr1 lpr2) double mutant plants, the hypersensitive phosphate deficiency response 2 (pdr2) mutant exhibited a reduced number of differential features in root exudates after Pi starvation, suggesting the involvement of PDR2-encoded P5-type ATPase in root exudation. Identification and analysis of coumarins revealed common and antagonistic regulatory pathways between Pi and Fe deficiency-induced coumarin secretion. The accumulation of oligolignols in root exudates after Pi deficiency was inversely correlated with Pi starvation-induced lignification at the root tips. The strongest oligolignol accumulation in root exudates was observed for the insensitive lpr1 lpr2 double mutant, which was accompanied by the absence of Pi deficiency-induced lignin deposition, suggesting a role of LPR ferroxidases in lignin polymerization during Pi starvation. PMID:26685189

  9. Analysis of root growth from a phenotyping data set using a density-based model.

    Science.gov (United States)

    Kalogiros, Dimitris I; Adu, Michael O; White, Philip J; Broadley, Martin R; Draye, Xavier; Ptashnyk, Mariya; Bengough, A Glyn; Dupuy, Lionel X

    2016-02-01

    Major research efforts are targeting the improved performance of root systems for more efficient use of water and nutrients by crops. However, characterizing root system architecture (RSA) is challenging, because roots are difficult objects to observe and analyse. A model-based analysis of RSA traits from phenotyping image data is presented. The model can successfully back-calculate growth parameters without the need to measure individual roots. The mathematical model uses partial differential equations to describe root system development. Methods based on kernel estimators were used to quantify root density distributions from experimental image data, and different optimization approaches to parameterize the model were tested. The model was tested on root images of a set of 89 Brassica rapa L. individuals of the same genotype grown for 14 d after sowing on blue filter paper. Optimized root growth parameters enabled the final (modelled) length of the main root axes to be matched within 1% of their mean values observed in experiments. Parameterized values for elongation rates were within ±4% of the values measured directly on images. Future work should investigate the time dependency of growth parameters using time-lapse image data. The approach is a potentially powerful quantitative technique for identifying crop genotypes with more efficient root systems, using (even incomplete) data from high-throughput phenotyping systems. PMID:26880747

  10. Aluminium localization and toxicity symptoms related to root growth inhibition in rice (Oryza sativa L.) seedlings

    Indian Academy of Sciences (India)

    M N Alvim; F T Ramos; D C Oliveira; R M S Isaias; M G C França

    2012-12-01

    We correlated root growth inhibition with aluminium (Al3+) localization and toxicity symptoms in rice roots using seedlings of two genotypes (tolerant and sensitive) that were exposed to different AlCl3 concentrations. Al3+ localization was evaluated by hematoxylin in primary roots and by morin in cross-sections of the root tips. Neutral invertase enzyme activity and callose (1$\\to$3, -D-glucan) accumulation were observed and compared with Al3+ accumulation sites. Root growth was inhibited by Al3+ in a concentration-specific manner and proportional to the increase of hematoxylin staining, being more pronounced in the sensitive genotype. Morin staining showed the presence of Al3+ deep within the roots of the sensitive genotype, indicating that the metal was able to penetrate beyond the first few cell layers. In the tolerant genotype, Al3+ penetration was restricted to the first two cell layers. Ruptures in exodermis and epidermis layers by lateral root protrusions in both genotypes allowed Al3+ to enter into the roots. More intense activity of invertase in roots of the tolerant genotype was also observed, which could be related to greater root growth of this cultivar when submitted to Al3+ stress. Moreover, Al3+-induced callose accumulation was a late response occurring in the same areas where Al3+ was present.

  11. Regulation of tissue-specific expression of SPATULA, a bHLH gene involved in carpel development, seedling germination, and lateral organ growth in Arabidopsis.

    Science.gov (United States)

    Groszmann, Michael; Bylstra, Yasmin; Lampugnani, Edwin R; Smyth, David R

    2010-03-01

    SPATULA is a bHLH transcription factor that promotes growth of tissues arising from the carpel margins, including the septum and transmitting tract. It is also involved in repressing germination of newly harvested seeds, and in inhibiting cotyledon, leaf, and petal expansion. Using a reporter gene construct, its expression profile was fully defined. Consistent with its known functions, SPT was expressed in developing carpel margin tissues, and in the hypocotyls and cotyledons of germinating seedlings, and in developing leaves and petals. It was also strongly expressed in tissues where no functions have been identified to date, including the dehiscence zone of fruits, developing anthers, embryos, and in the epidermal initials and new stele of root tips. The promoter region of SPT was dissected by truncation and deletion, and two main regions occupied by tissue-specific enhancers were identified. These were correlated with eight regions conserved between promoter regions of Arabidopsis, Brassica oleracea, and Brassica rapa. When transformed into Arabidopsis, the B. oleracea promoter drove expression in reproductive tissues mostly comparable to the equivalent Arabidopsis promoter. There is genetic evidence that SPT function in the gynoecium is associated with the perception of auxin. However, site-directed mutagenesis of three putative auxin-response elements had no detectable effect on SPT expression patterns. Even so, disruption of a putative E-box variant adjacent to one of these resulted in a loss of valve dehiscence zone expression. This expression was also specifically lost in mutants of another bHLH gene INDEHISCENT, indicating that IND may directly regulate SPT expression through this variant E-box. PMID:20176890

  12. Rhizobacterial volatiles and photosynthesis-related signals coordinate MYB72 expression in Arabidopsis roots during onset of induced systemic resistance and iron-deficiency responses.

    Science.gov (United States)

    Zamioudis, Christos; Korteland, Jolanda; Van Pelt, Johan A; van Hamersveld, Muriël; Dombrowski, Nina; Bai, Yang; Hanson, Johannes; Van Verk, Marcel C; Ling, Hong-Qing; Schulze-Lefert, Paul; Pieterse, Corné M J

    2015-10-01

    In Arabidopsis roots, the transcription factor MYB72 plays a dual role in the onset of rhizobacteria-induced systemic resistance (ISR) and plant survival under conditions of limited iron availability. Previously, it was shown that MYB72 coordinates the expression of a gene module that promotes synthesis and excretion of iron-mobilizing phenolic compounds in the rhizosphere, a process that is involved in both iron acquisition and ISR signaling. Here, we show that volatile organic compounds (VOCs) from ISR-inducing Pseudomonas bacteria are important elicitors of MYB72. In response to VOC treatment, MYB72 is co-expressed with the iron uptake-related genes FERRIC REDUCTION OXIDASE 2 (FRO2) and IRON-REGULATED TRANSPORTER 1 (IRT1) in a manner that is dependent on FER-LIKE IRON DEFICIENCY TRANSCRIPTION FACTOR (FIT), indicating that MYB72 is an intrinsic part of the plant's iron-acquisition response that is typically activated upon iron starvation. However, VOC-induced MYB72 expression is activated independently of iron availability in the root vicinity. Moreover, rhizobacterial VOC-mediated induction of MYB72 requires photosynthesis-related signals, while iron deficiency in the rhizosphere activates MYB72 in the absence of shoot-derived signals. Together, these results show that the ISR- and iron acquisition-related transcription factor MYB72 in Arabidopsis roots is activated by rhizobacterial volatiles and photosynthesis-related signals, and enhances the iron-acquisition capacity of roots independently of the iron availability in the rhizosphere. This work highlights the role of MYB72 in plant processes by which root microbiota simultaneously stimulate systemic immunity and activate the iron-uptake machinery in their host plants. PMID:26307542

  13. 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.

  14. 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.

  15. Effect of N Fertilizers on Root Growth and Endogenous Hormones in Strawberry

    Institute of Scientific and Technical Information of China (English)

    WANG Bo; LAI Tao; HUANG Qi-Wei; YANG Xing-Ming; SHEN Qi-Rong

    2009-01-01

    Endogenous hormones play an important role in the growth and development of roots. The objective of this research was to study the effect of four types of N fertilizers on the root growth of strawberry (Fragaria ananassa Duchesne) and the endogenous enzymes of indole-3-acetic acid (IAA), abscisic acid (ABA), and isopentenyl adenosine (iPA) in its roots and leaves using enzyme-linked immunosorbent assay. Application of all types of N fertilizers significantly depressed (P ≤ 0.05) root growth at 20 d after transplanting. Application of organic-inorganic fertilizer (OIF) as basal fertilizer had a significant negative effect (P ≤ 0.05) on root growth. The application of OIF and urea lowered the lateral root frequency in strawberry plants at 60 d (P ≤ 0.05) compared with the application of two organic fertilizers (OFA and OFB) and the control (CK). With the fertilizer treatments, there were the same concentrations of IAA and ABA in both roots and leaves at the initial growth stage (20 d), lower levels of IAA and ABA at the later stage (60 d), and higher iPA levels at all seedling stages as compared to those of CK. Thus, changes in the concentrations of endogenous phytohormones in strawberry plants could be responsible for the morphological changes of roots due to fertilization.

  16. Arabidopsis phosphatidylinositol monophosphate 5-kinase 2 is involved in root gravitropism through regulation of polar auxin transport by affecting the cycling of PIN proteins

    OpenAIRE

    Mei, Yu; Jia, Wen-Jing; Chu, Yu-Jia; Xue, Hong-Wei

    2011-01-01

    Phosphatidylinositol monophosphate 5-kinase (PIP5K) catalyzes the synthesis of PI-4,5-bisphosphate (PtdIns(4,5)P2) by phosphorylation of PI-4-phosphate at the 5 position of the inositol ring, and is involved in regulating multiple developmental processes and stress responses. We here report on the functional characterization of Arabidopsis PIP5K2, which is expressed during lateral root initiation and elongation, and whose expression is enhanced by exogenous auxin. The knockout mutant pip5k...

  17. MiRNA398b and miRNA398c are involved in the regulation of the SOD response in uranium-exposed Arabidopsis thaliana roots

    OpenAIRE

    Saenen, Eline; Horemans, Nele; Vanhoudt, Nathalie; Vandenhove, H.; Biermans, Geert; Hees, M. van; WANNIJN, J.; Vangronsveld, Jaco; Cuypers, Ann

    2015-01-01

    The chemical speciation of uranium (U), and hence its toxicity, is strongly dependent on pH. However, oxidative stress responses after U exposure have mainly been investigated in Arabidopsis thaliana plants at pH 5.5, the ideal pH for growing plants in a hydroponic setup. As the pH of pore water can vary strongly, the aim of this study is to investigate oxidative stress responses induced in roots of A. thaliana plants exposed to different U concentrations at pH 4.5 and hence at a high free...

  18. Association between productivity, root growth and carbon isotope discrimination in Paseolus vulgaris under water deficit

    International Nuclear Information System (INIS)

    In order to evaluate relations between root growth, productivity and 13C (Δ) during photosynthesis in C3 plants such as common bean (Phaseolus vulgaris L.), Δ and crop growth parameters, including biomass production, grain yield and root length density, were determined for ten bean genotypes grown under rainfed conditions at two sites in Colombia which differed primarily in soil fertility and effective rooting depth. The 10 genotypes were also grown under irrigation at the more fertile site. Under rainfed conditions, root length density was positively correlated with Δ in the fertile Mollisol at Palmira, and was also positively correlated with Δ in the infertile Oxisol at Quilichao if one possibly aberrant genotype was excluded. At Palmira, reduced crop growth and seed yield were associated with low Δ values. At Quilichao, intermediate Δ values were associated with the greatest growth and yield. Under irrigation at Palmira there was no association between growth or yield and and Δ. 17 refs., 5 tabs., 3 figs

  19. Root growth conditions in the topsoil as affected by tillage intensity

    DEFF Research Database (Denmark)

    Kadziene, Grazina; Munkholm, Lars Juhl; Mutegi, James

    2011-01-01

    treatments were direct drilling (D), harrowing 8–10 cm (H), and ploughing (P) to 20 cm depth. A chisel coulter drill was used in the H and D treatments and a traditional seed drill in the P treatment. Undisturbed soil cores were collected in November 2008 at soil field moisture capacity from the 4–8 and 12......Many studies have reported impeded root growth in topsoil under reduced tillage or direct drilling, but few have quantified the effects on the least limiting water range for root growth. This study explored the effects of tillage intensity on critical soil physical conditions for root growth in the...

  20. Inheritance and gene expression of a root-growth inhibiting mutant in rice (Oryza sativa L.)

    International Nuclear Information System (INIS)

    Full text: A root-growth inhibiting mutant was induced in the dwarf mutant line, 'Fukei 71', through ethylene-imine. The mutant is characterised by the excessive inhibition of both seminal and crown roots elongation just after germination, although its shoots grow nearly normal. To study the genetics, the mutant was crossed with its original line 'Fukei 71' and some other normal cultivars. Results show that the root-growth inhibition is controlled by a recessive gene (rt), independent of the dwarf gene, d-50(t) locus in Fukei 71. For elucidating the gene action on root morphogenesis, histological and cytological experiments were carried out using a longitudinal and transverse thin section of seminal and/or crown root tips. Observations suggest that the rt gene affects the normal formation of the epidermal system which is differentiated from the protoderm of the root apical meristem. (author)

  1. Consequences of insect herbivory on grape fine root systems with different growth rates.

    Science.gov (United States)

    Bauerle, T L; Eissenstat, D M; Granett, J; Gardner, D M; Smart, D R

    2007-07-01

    Herbivory tolerance has been linked to plant growth rate where plants with fast growth rates are hypothesized to be more tolerant of herbivory than slower-growing plants. Evidence supporting this theory has been taken primarily from observations of aboveground organs but rarely from roots. Grapevines differing in overall rates of new root production, were studied in Napa Valley, California over two growing seasons in an established vineyard infested with the sucking insect, grape phylloxera (Daktulosphaira vitifoliae Fitch). The experimental vineyard allowed for the comparison of two root systems that differed in rates of new root tip production (a 'fast grower', Vitis berlandieri x Vitis rupestris cv. 1103P, and a slower-growing stock, Vitis riparia x Vitis rupestris cv. 101-14 Mgt). Each root system was grafted with a genetically identical shoot system (Vitis vinifera cv. Merlot). Using minirhizotrons, we did not observe any evidence of spatial or temporal avoidance of insect populations by root growth. Insect infestations were abundant throughout the soil profile, and seasonal peaks in phylloxera populations generally closely followed peaks in new root production. Our data supported the hypothesis that insect infestation was proportional to the number of growing tips, as indicated by similar per cent infestation in spite of a threefold difference in root tip production. In addition, infested roots of the fast-growing rootstock exhibited somewhat shorter median lifespans (60 d) than the slower-growing rootstock (85 d). Lifespans of uninfested roots were similar for the two rootstocks (200 d). As a consequence of greater root mortality of younger roots, infested root populations in the fast-growing rootstock had an older age structure. While there does not seem to be a trade-off between potential growth rate and relative rate of root infestation in these cultivars, our study indicates that a fast-growing root system may more readily shed infested roots that are

  2. Root growth of Lotus corniculatus interacts with P distribution in young sandy soil

    OpenAIRE

    Felderer, B.; K. M. Boldt-Burisch; Schneider, B.U.; R. F. J. Hüttl; R. Schulin

    2013-01-01

    Large areas of land are restored with unweathered soil substrates following mining activities in eastern Germany and elsewhere. In the initial stages of colonization of such land by vegetation, plant roots may become key agents in generating soil formation patterns by introducing gradients in chemical and physical soil properties. On the other hand, such patterns may be influenced by root growth responses to pre-existing substrate heterogeneities. In particular, the roots of many plants were ...

  3. Auxin, the organizer of the environmental/hormonal signals for root hair growth

    Directory of Open Access Journals (Sweden)

    Hyung-Taeg eCho

    2013-11-01

    Full Text Available The root hair development is controlled by diverse factors such as fate-determining developmental cues, auxin-related environmental factors, and hormones. In particular, the soil environmental factors are important as they maximize their absorption by modulating root hair development. These environmental factors affect the root hair developmental process by making use of diverse hormones. These hormonal factors interact with each other to modulate root hair development in which auxin appears to form the most intensive networks with the pathways from environmental factors and hormones. Moreover, auxin action for root hair development is genetically located immediately upstream of the root hair-morphogenetic genes. These observations suggest that auxin plays as an organizing node for environmental/hormonal pathways to modulate root hair growth.

  4. Vitamin D3 affects growth and Ca2+ uptake by Phaseolus vulgaris roots cultured in vitro

    International Nuclear Information System (INIS)

    Vitamin D3 at low concentration (10−9 M) inhibited the growth of Phaseolus vulgaris L. (cv. Contrancha) roots in vitro as measured by elongation (14 h) and [3H]-leucine incorporation into protein (2 h), and increased their labelling with 45Ca2+ (2 h). Cycloheximide and puromycin (50 u.M) blocked vitamin D3 stimulation of root 45Ca2+ labelling, indicating that it is mediated by de novo protein synthesis. The calcium ionophore X-537A (10−5JW) induced similar changes both in root elongation and 45Ca2+ uptake (14 h). This may indicate that the inhibitory effects of the sterol on root growth are mediated by changes in Ca2+ fluxes. However, this interpretation should be further strengthened by additional studies as the ionophore may have acted on root growth, affecting physiological processes other than Ca2+ transport. (author)

  5. Genetic Improvement of Root Growth Contributes to Efficient Phosphorus Acquisition in maize (Zea mays L.)

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yi-kai; CHEN Fan-jun; CHEN Xiao-chao; LONG Li-zhi; GAO Kun; YUAN Li-xing; ZHANG Fu-suo; MI Guo-hua

    2013-01-01

    Maize plants adapt to low phosphorus (P) stress by increasing root growth. It is of importance to know the extent to which genetic improvement of root growth can enhance P acquisiton. In the present study, the contribution of root growth improvement to efficient P acquisition was evaluated in two soils using T149 and T222, a pair of near isogenic maize testcrosses which were derived from a backcross BC4F3 population. T149 and T222 showed no difference in shoot biomass and leaf area under normal growth conditions, but differed greatly in root growth. T149 had longer lateral roots and a larger root surface area compared to T222. In calcareous soil, when P was insufficient, i.e., when P was either supplied as KH2PO4 at a concentration of 50 mg P kg-1 soil, or in the form of Phy-P, Ca3-P or Ca10-P, a 43%increase in root length in T149 compared to T222 resulted in an increase in P uptake by 53%, and shoot biomass by 48%. In acid soil, however, when P supply was insufficient, i.e., when P was supplied as KH2PO4 at a concentration of 100 mg P kg-1 soil, or in the form of Phy-P, Fe-P or Al-P, a 32%increase in root length in T149 compared to T222 resulted in an increase in P uptake by only 12%, and shoot biomass by 7%. No significant differences in the exudation of organic acids and APase activity were found between the two genotypes. It is concluded that genetic improvement of root growth can efficiently increase P acquisition in calcareous soils. In acid soils, however, improvements in the physiological traits of roots, in addition to their size, seem to be required for efficient P acquisition.

  6. Effect of soil acidification on root growth, nutrient and water uptake

    International Nuclear Information System (INIS)

    Soil acidification poses various types of stress to plants, especially Al and H+ toxicity in roots and Mg and Ca deficiency in roots and shoots. The importance of the various types of stress varies with plant species, location and time. Average data of the chemical composition of the bulk soil or of the molar Ca/Al or Mg/Al ratios in the soil solution without consideration of the Al species are of limited value for precise conclusions of the actual, or for predictions of the potential risk of soil-acidity-induced inhibition of root growth and of nutritional imbalances. The root-induced changes in the rhizosphere and the consequences for Al toxicity and nutrient acquisition by plants deserve more attention. Further it should be considered that roots are not only required for anchoring higher plants in the soil and for nutrient and water uptake. Roots are also important sites for synthesis of phytohormones, cytokinins and abscisic acid in particular, which are transported into the shoots and act either as signals for the water status at the soil-root interface (ABA) or as compounds required for growth and development. Inhibition in root growth may therefore affect shoot growth by means other than water and nutrient supply. (orig./vhe)

  7. Seasonal branch and fine root growth of juvenile loblolly pine five growing seasons after fertilization.

    Science.gov (United States)

    Sword, M. A.; Gravatt, D. A.; Faulkner, P. L.; Chambers, J. L.

    1996-01-01

    In 1989, we established two replications of two fertilization treatments in a 10-year-old loblolly pine (Pinus taeda L.) plantation. Between March and September 1993, branch internode and needle fascicle expansion in the upper and lower third of crowns were measured weekly on three south-facing branches of each of four trees, and new root initiation and elongation were measured at 10-day intervals in three vertical rhizotrons per plot. In one replication, soil water content was measured daily. Fertilization significantly increased the expansion of first flush internodes in the upper crown and first flush needle fascicles in the upper and lower crown. New root growth was stimulated by fertilization in the second half of the growing season. The timing of root growth responses to fertilization corresponded to branch phenologies in the upper and lower crown that were conducive to increased basipetal transport of photosynthate. We conclude, therefore, that new root growth was linked to source-sink activities in the crown. Root initiation was greater in the upper than in the lower part of the soil profile; however, as the growing season progressed and water deficit increased, this relationship was reversed. The effect of soil depth on seasonal root growth was closely associated with water availability, suggesting that root initiation deep in the soil profile is critical for the continued production of new roots in environments subjected to short-term, but relatively severe, water deficits. PMID:14871782

  8. Cyclin-like F-box protein plays a role in growth and development of the three model species Medicago truncatula, Lotus japonicus, and Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Boycheva I

    2015-08-01

    Full Text Available Irina Boycheva,1 Valya Vassileva,2 Miglena Revalska,1 Grigor Zehirov,2 Anelia Iantcheva1 1Department of Functional Genetics Legumes, 2AgroBioInstitute, Department of Plant Stress Molecular Biology, Institute of Plant Physiology and Genetics, Sofia, Bulgaria Abstract: In eukaryotes, F-box proteins are one of the main components of the SCF complex that belongs to the family of ubiquitin E3 ligases, which catalyze protein ubiquitination and maintain the balance between protein synthesis and degradation. In the present study, we clarified the role and function of the gene encoding cyclin-like F-box protein from Medicago truncatula using transgenic plants of the model species M. truncatula, Lotus japonicas, and Arabidopsis thaliana generated by Agrobacterium-mediated transformation. Morphological and transcriptional analyses combined with flow cytometry and histochemistry demonstrated the participation of this protein in many aspects of plant growth and development, including processes of indirect somatic embryogenesis and symbiotic nodulation. The cyclin-like F-box gene showed expression in all plant organs and tissues comprised of actively dividing cells. The observed variations in root and hypocotyl growth, leaf and silique development, ploidy levels, and leaf parameters in the obtained transgenic lines demonstrated the effects of this gene on organ development. Furthermore, knockdown of cyclin-like F-box led to accumulation of higher levels of the G2/M transition-specific gene cyclin B1:1 (CYCB1:1, suggesting its possible role in cell cycle control. Together, the collected data suggest a similar role of the cyclin-like F-box protein in the three model species, providing evidence for the functional conservation of the studied gene. Keywords: cyclin-like F-box, model legumes, Arabidopsis thaliana, plant growth, plant development, cell cycle

  9. Arabidopsis thaliana glyoxalase 2-1 is required during abiotic stress but is not essential under normal plant growth.

    Directory of Open Access Journals (Sweden)

    Sriram Devanathan

    Full Text Available The glyoxalase pathway, which consists of the two enzymes, GLYOXALASE 1 (GLX 1 (E.C.: 4.4.1.5 and 2 (E.C.3.1.2.6, has a vital role in chemical detoxification. In Arabidopsis thaliana there are at least four different isoforms of glyoxalase 2, two of which, GLX2-1 and GLX2-4 have not been characterized in detail. Here, the functional role of Arabidopsis thaliana GLX2-1 is investigated. Glx2-1 loss-of-function mutants and plants that constitutively over-express GLX2-1 resemble wild-type plants under normal growth conditions. Insilico analysis of publicly available microarray datasets with ATTEDII, Mapman and Genevestigator indicate potential role(s in stress response and acclimation. Results presented here demonstrate that GLX2-1 gene expression is up-regulated in wild type Arabidopsis thaliana by salt and anoxia stress, and by excess L-Threonine. Additionally, a mutation in GLX2-1 inhibits growth and survival during abiotic stresses. Metabolic profiling studies show alterations in the levels of sugars and amino acids during threonine stress in the plants. Elevated levels of polyamines, which are known stress markers, are also observed. Overall our results suggest that Arabidopsis thaliana GLX2-1 is not essential during normal plant life, but is required during specific stress conditions.

  10. Acclimation of Arabidopsis thaliana to long-term CO{sub 2} enrichment and nitrogen supply is basically a matter of growth rate adjustment

    Energy Technology Data Exchange (ETDEWEB)

    Tocquin, P.; Ormenese, S.; Pieltain, A.; Detry, N.; Bernier, G.; Perilleux, C. [Univ. of Liege, Dept. of Life Sciences, Lab. of Plant Physiology, Liege (Belgium)

    2006-12-15

    The long-term response of Arabidopsis thaliana to increasing CO{sub 2} was evaluated in plants grown in 800 {mu}l l{sup -1} CO{sub 2} from sowing and maintained, in hydroponics, on three nitrogen supplies: 'low', 'medium' and 'high'. The global response to high CO{sub 2} and N-supply was evaluated by measuring growth parameters in parallel with photosynthetic activity, leaf carbohydrates, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) messenger RNA and protein, stomatal conductance (g-s) and density. CO{sub 2} enrichment was found to stimulate biomass production, whatever the N-supply. This stimulation was transient on low N-supply and persisted throughout the whole vegetative growth only in high N-supply. Acclimation on low N-high C0{sub 2} was not associated with carbohydrate accumulation or with a strong reduction in Rubisco amount or activity. At high N-supply, growth stimulation by high CO{sub 2} was mainly because of the acceleration of leaf production and expansion while other parameters such as specific leaf area, root/shoot ratio and g{sub s} appeared to be correlated with total leaf area. Our results thus suggest that, in strictly controlled and stable growing conditions, acclimation of A. thaliana to long-term CO{sub 2} enrichment is mostly controlled by growth rate adjustment. (au)

  11. Phytohormone regulation of root growth triggered by P deficiency or Al toxicity.

    Science.gov (United States)

    Sun, Lili; Tian, Jiang; Zhang, Haiyan; Liao, Hong

    2016-06-01

    Phosphorus (P) deficiency and aluminum (Al) toxicity often coexist and limit plant growth on acid soils. It has been well documented that both P deficiency and Al toxicity alter root growth, including inhibition of primary roots and promotion of lateral roots. This suggests that plants adapt to both stresses through a common regulation pathway. Although an expanding set of results shows that phytohormones play vital roles in controlling root responses to Pi starvation and Al toxicity, it remains largely unknown whether P and Al coordinately regulate root growth through interacting phytohormone biosynthesis and signal transduction pathways. This review provides a summary of recent results concerning the influences of P deficiency and Al toxicity on root growth through the action of phytohormones, most notably auxin and ethylene. The objective is to facilitate increasing insights into complex responses of plants to adverse factors common on acid soils, which can spur development of 'smart' cultivars with better root growth and higher yield on these globally distributed marginal soils. PMID:27190050

  12. Growth and microtubule orientation of Zea mays roots subjected to osmotic stress

    Science.gov (United States)

    Blancaflor, E. B.; Hasenstein, K. H.

    1995-01-01

    Previous work has shown that microtubule (MT) reorientation follows the onset of growth inhibition on the lower side of graviresponding roots, indicating that growth reduction can occur independently of MT reorientation. To test this observation further, we examined whether the reduction in growth in response to osmotic stress is correlated with MT reorientation. The distribution and rate of growth in maize roots exposed to 350 mOsm sorbitol and KCl or 5 mM Mes/Tris buffer were measured with a digitizer. After various times roots were processed for indirect immunofluorescence microscopy. Application of sorbitol or KCl had no effect on the organization of MTs in the apical 2 mm of the root but resulted in striking and different effects in the basal region of the root. Sorbitol treatment caused rapid appearance of oval to circular holes in the microtubular array that persisted for at least 9 h. Between 30 min and 4 h of submersion in KCl, MTs in cortical cells 4 mm and farther from the quiescent center began to reorient oblique to the longitudinal axis. After 9 h, the alignment of MTs had shifted to parallel to the root axis but MTs of the epidermal cells remained transverse. In KCl-treated roots MT reorientation appeared to follow a pattern of development similar to that in controls but without elongation. Our data provide additional evidence that MT reorientation is not the cause but a consequence of growth inhibition.

  13. Root growth reacts rapidly and more pronounced than shoot growth towards increasing light intensity in tobacco seedlings.

    Science.gov (United States)

    Walter, Achim; Nagel, Kerstin A

    2006-09-01

    Light intensity is crucial for plant growth and often fluctuates on a small time scale due to altering climate conditions or sunflecks. Recently, we performed a study that looked into the growth effect of a sudden elevation of light intensity on Nicotiana tabacum seedlings.1 It was shown that an increase in light intensity leads to a pronounced increase of root-shoot-ratio as root growth reacts strongly and rapidly to an increase of light intensity. In transition experiments from low (60 micromol m(-2) s(-1)) to high (300 micromol m(-2) s(-1)) light intensity, root growth increased by a factor of four within four days, reaching the steady-state level measured in plants that were cultivated in high-light conditions. During the first three hours after light increase, strong fluctuations of the velocity of the root tip were observed that were putatively caused by a superposition of hydraulic and photosynthetic acclimation to the altered conditions. Experiments with externally applied sucrose and with transgenic plants having reduced capacity for sucrose synthesis indicated clearly that increasing light intensity rapidly enhanced root growth by elevating sucrose export from shoot to root. PMID:19704663

  14. Auxin, ethylene and the regulation of root growth under mechanical impedance

    Science.gov (United States)

    Sharma, Rameshwar; Santisree, Parankusam; Nongmaithem, Sapana; Sreelakshmi, Yellamaraju

    2012-07-01

    Among the multitude functions performed by plant roots, little information is available about the mechanisms that allow roots to overcome the soil resistance, in order to grow in the soil to obtain water and nutrient. Tomato (Solanum lycopersicum) seedlings grown on horizontally placed agar plates showed a progressive decline in the root length with the increasing impedance of agar media. The incubation with 1-methylcyclopropane (1-MCP), an inhibitor of ethylene perception, led to aerial growth of roots. In contrast, in absence of 1-MCP control roots grew horizontally anchored to the agar surface. Though 1-MCP-treated and control seedlings showed differential ability to penetrate in the agar, the inhibition of root elongation was nearly similar for both treatments. While increased mechanical impedance also progressively impaired hypocotyl elongation in 1-MCP treated seedlings, it did not affect the hypocotyl length of control seedlings. The decline in root elongation was also associated with increased expression of DR5::GUS activity in the root tip signifying accumulation of auxin at the root tip. The increased expression of DR5::GUS activity in the root tip was also observed in 1-MCP treated seedlings, indicating independence of this response from ethylene signaling. Our results indicate operation of a sensing mechanism in root that likely operates independently of ethylene but involves auxin to determine the degree of impedance of the substratum.

  15. Recovery of root growth and physiological characters in cotton after salt stress relief

    OpenAIRE

    Wen-Qi Guo; Pei-Tong Zhang; Chun-Hong Li; Jian-Mei Yin; Xiao-Yong Han

    2015-01-01

    Crop growth in a saline environment depends on its tolerance to salt stress and capacity to recover after salt stress relief. To evalúate recovery mechanisms in cotton after salt stress relief, the changes of plants growth, root vigor, lipid peroxidation, antioxidant enzymes activity, organic solutes in root after salt stress relief were studied for two cotton (Gossypium hirsutum L.) cultivars (Lumianyan 37 and Sumian 22) grown under control (salt content of soil grown cotton was maintained a...

  16. Parameterising root system growth models using 2D neutron radiography images

    Science.gov (United States)

    Schnepf, Andrea; Felderer, Bernd; Vontobel, Peter; Leitner, Daniel

    2013-04-01

    Root architecture is a key factor for plant acquisition of water and nutrients from soil. In particular in view of a second green revolution where the below ground parts of agricultural crops are important, it is essential to characterise and quantify root architecture and its effect on plant resource acquisition. Mathematical models can help to understand the processes occurring in the soil-plant system, they can be used to quantify the effect of root and rhizosphere traits on resource acquisition and the response to environmental conditions. In order to do so, root architectural models are coupled with a model of water and solute transport in soil. However, dynamic root architectural models are difficult to parameterise. Novel imaging techniques such as x-ray computed tomography, neutron radiography and magnetic resonance imaging enable the in situ visualisation of plant root systems. Therefore, these images facilitate the parameterisation of dynamic root architecture models. These imaging techniques are capable of producing 3D or 2D images. Moreover, 2D images are also available in the form of hand drawings or from images of standard cameras. While full 3D imaging tools are still limited in resolutions, 2D techniques are a more accurate and less expensive option for observing roots in their environment. However, analysis of 2D images has additional difficulties compared to the 3D case, because of overlapping roots. We present a novel algorithm for the parameterisation of root system growth models based on 2D images of root system. The algorithm analyses dynamic image data. These are a series of 2D images of the root system at different points in time. Image data has already been adjusted for missing links and artefacts and segmentation was performed by applying a matched filter response. From this time series of binary 2D images, we parameterise the dynamic root architecture model in the following way: First, a morphological skeleton is derived from the binary

  17. Arabidopsis phosphatidylinositol monophosphate 5-kinase 2 is involved in root gravitropism through regulation of polar auxin transport by affecting the cycling of PIN proteins

    Institute of Scientific and Technical Information of China (English)

    Yu Mei; Wen-Jing Jia; Yu-Jia Chu; Hong-Wei Xue

    2012-01-01

    Phosphatidylinositol monophosphate 5-kinase(PIP5K)catalyzes the synthesis of PI-4,5-bisphosphate(PtdIns(4,5)P2)by phosphorylation of PI-4-phosphate at the 5 position of the inositol ring,and is involved in regulating multiple developmental processes and stress responses.We here report on the functional characterization of Arabidopsis PIP5K2,which is expressed during lateral root initiation and elongation,and whose expression is enhanced by exogenous auxin.The knockout mutant pip5k2 shows reduced lateral root formation,which could be recovered with exogenous auxin,and interestingly,delayed root gravity response that could not be recovered with exogenous auxin.Crossing with the DR5-GUS marker line and measurement of free IAA content confirmed the reduced auxin accumulation in pip5k2.In addition,analysis using the membrane-selective dye FM4-64 revealed the decelerated vesicle trafficking caused by PtdIns(4,5)P2 reduction,which hence results in suppressed cycling of PIN proteins(PIN2 and 3),and delayed redistribution of PIN2 and auxin under gravistimulation in pipSk2 roots.On the contrary,PtdIns(4,5)P2 significantly enhanced the vesicle trafficking and cycling of PIN proteins.These results demonstrate that PIP5K2 is involved in regulating lateral root formation and root gravity response,and reveal a critical role of PIP5K2/Ptdlns(4,5)P2 in root development through regulation of PIN proteins,providing direct evidence of crosstalk between the phosphatidylinositol signaling pathway and auxin response,and new insights into the control of polar auxin transport.

  18. Arabidopsis phosphatidylinositol monophosphate 5-kinase 2 is involved in root gravitropism through regulation of polar auxin transport by affecting the cycling of PIN proteins.

    Science.gov (United States)

    Mei, Yu; Jia, Wen-Jing; Chu, Yu-Jia; Xue, Hong-Wei

    2012-03-01

    Phosphatidylinositol monophosphate 5-kinase (PIP5K) catalyzes the synthesis of PI-4,5-bisphosphate (PtdIns(4,5)P(2)) by phosphorylation of PI-4-phosphate at the 5 position of the inositol ring, and is involved in regulating multiple developmental processes and stress responses. We here report on the functional characterization of Arabidopsis PIP5K2, which is expressed during lateral root initiation and elongation, and whose expression is enhanced by exogenous auxin. The knockout mutant pip5k2 shows reduced lateral root formation, which could be recovered with exogenous auxin, and interestingly, delayed root gravity response that could not be recovered with exogenous auxin. Crossing with the DR5-GUS marker line and measurement of free IAA content confirmed the reduced auxin accumulation in pip5k2. In addition, analysis using the membrane-selective dye FM4-64 revealed the decelerated vesicle trafficking caused by PtdIns(4,5)P(2) reduction, which hence results in suppressed cycling of PIN proteins (PIN2 and 3), and delayed redistribution of PIN2 and auxin under gravistimulation in pip5k2 roots. On the contrary, PtdIns(4,5)P(2) significantly enhanced the vesicle trafficking and cycling of PIN proteins. These results demonstrate that PIP5K2 is involved in regulating lateral root formation and root gravity response, and reveal a critical role of PIP5K2/PtdIns(4,5)P(2) in root development through regulation of PIN proteins, providing direct evidence of crosstalk between the phosphatidylinositol signaling pathway and auxin response, and new insights into the control of polar auxin transport. PMID:21894193

  19. Comparison of root growth and morphological responses to Cadmium and Nickel in two maize cultivars

    Directory of Open Access Journals (Sweden)

    R. Fiala

    2013-04-01

    Full Text Available Two maize cultivars ‘Premjia 190 MB’ and ‘Blitz 160 MB’, in their seedling stage were exposed for 3 days to Cd 2+ and Ni 2+ , separately and also jointly, in concentrations that caused significant inhibition but not cessation of root growth. Primary root growth, cell viability, tissue organization and root system morphology of both cultivars were similar under control conditions. Length of primary roots of both cultivars was significantly reduced by Cd and Ni ions and by the joint treatment (Cd+Ni, under which also early reduction of cell viability occurred. Comparing the two metals, Cd and Cd+Ni proved to be more toxic than Ni alone, with the exception of the effects on ‘Blitz 160 MB’lateral root formation. Comparing the cultivars, ‘Premija190 MB’ seemed to be more sensitive to Cd and Cd+Ni than to Ni in all studied parameters, while the early reduction of cell viability, activity of lateral root formation and root thickness in ‘Blitz 160 MB’ were more sensitive to Cd+Ni and Ni. The studied growth and morphological characteristics of roots suggest that, at least in the stage of 5 to 6-day-old seedlings, the cultivar ‘Blitz 160 MB’ responded more sensitively to experimentally induced heavy metal stress conditions than did the cultivar ‘Premjia 190 MB’.

  20. Effect of Irrigation Timing on Root Zone Soil Temperature, Root Growth and Grain Yield and Chemical Composition in Corn

    Directory of Open Access Journals (Sweden)

    Xuejun Dong

    2016-05-01

    Full Text Available High air temperatures during the crop growing season can reduce harvestable yields in major agronomic crops worldwide. Repeated and prolonged high night air temperature stress may compromise plant growth and yield. Crop varieties with improved heat tolerance traits as well as crop management strategies at the farm scale are thus needed for climate change mitigation. Crop yield is especially sensitive to night-time warming trends. Current studies are mostly directed to the elevated night-time air temperature and its impact on crop growth and yield, but less attention is given to the understanding of night-time soil temperature management. Delivering irrigation water through drip early evening may reduce soil temperature and thus improve plant growth. In addition, corn growers typically use high-stature varieties that inevitably incur excessive respiratory carbon loss from roots and transpiration water loss under high night temperature conditions. The main objective of this study was to see if root-zone soil temperature can be reduced through drip irrigation applied at night-time, vs. daytime, using three corn hybrids of different above-ground architecture in Uvalde, TX where day and night temperatures during corn growing season are above U.S. averages. The experiment was conducted in 2014. Our results suggested that delivering well-water at night-time through drip irrigation reduced root-zone soil temperature by 0.6 °C, increase root length five folds, plant height 2%, and marginally increased grain yield by 10%. However, irrigation timing did not significantly affect leaf chlorophyll level and kernel crude protein, phosphorous, fat and starch concentrations. Different from our hypothesis, the shorter, more compact corn hybrid did not exhibit a higher yield and growth as compared with taller hybrids. As adjusting irrigation timing would not incur an extra cost for farmers, the finding reported here had immediate practical implications for farm

  1. Fe-Chlorophyllin Promotes the Growth of Wheat Roots Associated with Nitric Oxide Generation

    OpenAIRE

    Hui Jiang; Yong Ren; Liefeng Zhang; Yifan Wang; Min Tong

    2010-01-01

    : Effects of Fe-chlorophyllin on the growth of wheat root were investigated in this study. We found that Fe-chlorophyllin can promote root growth. The production of nitric oxide in wheat root was detected using DAF-2DA fluorescent emission. The intensity of fluorescent in the presence of 0.1 mg/L Fe-chlorophyllin was near to that observed with the positive control of sodium nitroprusside (SNP), the nitric oxide donor. IAA oxidase activity decreased with all treatments of Fe-chlorophyllin from...

  2. Comparative effects of auxin and abscisic acid on growth, hydrogen ion efflux and gravitropism in primary roots of maize

    Science.gov (United States)

    Evans, M. L.; Mulkey, T. J.

    1984-01-01

    In order to test the idea that auxin action on root growth may be mediated by H(+) movement, the correlation of auxin action on growth and H(+) movement in roots was examined along with changes in H(+) efflux patterns associated with the asymmetric growth which occurs during gravitropism. The effects of indoleacetic acid (IAA) and abscisic acid (AbA) on growth, H(+) secretion, and gravitropism in roots were compared. Results show a close correlation existent between H(+) efflux and growth in maize roots. In intact roots there is strong H(+) efflux from the elongation zone. Growth-promoting concentrations of IAA stimulate H(+) efflux. During gravitropism the H(+) efflux from the elongation zone becomes asymmetric; the evidence indicates that auxin redistribution contributes to the development of acid efflux asymmetry. That AbA stimulates root growth is reflected in its ability to stimulate H(+) efflux from apical root segments.

  3. Potential sites of bioactive gibberellin production during reproductive growth in Arabidopsis.

    Science.gov (United States)

    Hu, Jianhong; Mitchum, Melissa G; Barnaby, Neel; Ayele, Belay T; Ogawa, Mikihiro; Nam, Edward; Lai, Wei-Chu; Hanada, Atsushi; Alonso, Jose M; Ecker, Joseph R; Swain, Stephen M; Yamaguchi, Shinjiro; Kamiya, Yuji; Sun, Tai-Ping

    2008-02-01

    Gibberellin 3-oxidase (GA3ox) catalyzes the final step in the synthesis of bioactive gibberellins (GAs). We examined the expression patterns of all four GA3ox genes in Arabidopsis thaliana by promoter-beta-glucuronidase gene fusions and by quantitative RT-PCR and defined their physiological roles by characterizing single, double, and triple mutants. In developing flowers, GA3ox genes are only expressed in stamen filaments, anthers, and flower receptacles. Mutant plants that lack both GA3ox1 and GA3ox3 functions displayed stamen and petal defects, indicating that these two genes are important for GA production in the flower. Our data suggest that de novo synthesis of active GAs is necessary for stamen development in early flowers and that bioactive GAs made in the stamens and/or flower receptacles are transported to petals to promote their growth. In developing siliques, GA3ox1 is mainly expressed in the replums, funiculi, and the silique receptacles, whereas the other GA3ox genes are only expressed in developing seeds. Active GAs appear to be transported from the seed endosperm to the surrounding maternal tissues where they promote growth. The immediate upregulation of GA3ox1 and GA3ox4 after anthesis suggests that pollination and/or fertilization is a prerequisite for de novo GA biosynthesis in fruit, which in turn promotes initial elongation of the silique. PMID:18310462

  4. Expression of an Antisense BcMF3 Affects Microsporogenesis and Pollen Tube Growth in Arabidopsis

    Institute of Scientific and Technical Information of China (English)

    LIU Le-cheng; CAO Jia-shu; YU Xiao-lin; XIANG Xun; FEI Yong-jun

    2006-01-01

    In an effort to provide some information relevant to the molecular mechanism of genic male sterility in plants, BcMF3 gene that encodes a pectin methylesterase was isolated from the fertile B line of Chinese cabbage-pak-choi (Brassica rapa ssp.chinensis, syn. B. campestris ssp. chinensis). In the present paper, a 455-bp antisense cDNA fragment of BcMF3 was introduced to binary vector pBI121, and then was mobilized into Agrobacterium tumefaciens strain LBA4404. The A.tumefaciens harboring the BcMF3 antisense fragment was transformed to Arabidopsis thaliana by floral dip. Scanning electronic microscopy examination demonstrated that 47.8% of BcMF3 antisense pollen grains exhibited abnormal shape,which might lead to decreased germination of pollens, suggesting that the product of BcMF3 gene plays an important role during microsporogenesis. The evidence on burst of 45.7% of BcMF3 antisense pollen tubes in vitro and a majority of BcMF3 antisense pollens restricted within the stigmatic tissue revealed that BcMF3 is involved in aiding the growth of pollen tubes. The results suggest that BcMF3 acts at both stages of microsporogensis and pollen tube growth.

  5. Cell wall-bound cationic and anionic class III isoperoxidases of pea root: biochemical characterization and function in root growth.

    Science.gov (United States)

    Kukavica, Biljana M; Veljovicc-Jovanovicc, Sonja D; Menckhoff, Ljiljana; Lüthje, Sabine

    2012-07-01

    Cell wall isolated from pea roots was used to separate and characterize two fractions possessing class III peroxidase activity: (i) ionically bound proteins and (ii) covalently bound proteins. Modified SDS-PAGE separated peroxidase isoforms by their apparent molecular weights: four bands of 56, 46, 44, and 41kDa were found in the ionically bound fraction (iPOD) and one band (70kDa) was resolved after treatment of the cell wall with cellulase and pectinase (cPOD). Isoelectric focusing (IEF) patterns for iPODs and cPODs were significantly different: five iPODs with highly cationic pI (9.5-9.2) were detected, whereas the nine cPODs were anionic with pI values between pH 3.7 and 5. iPODs and cPODs showed rather specific substrate affinity and different sensitivity to inhibitors, heat, and deglycosylation treatments. Peroxidase and oxidase activities and their IEF patterns for both fractions were determined in different zones along the root and in roots of different ages. New iPODs with pI 9.34 and 9.5 were induced with root growth, while the activity of cPODs was more related to the formation of the cell wall in non-elongating tissue. Treatment with auxin that inhibits root growth led to suppression of iPOD and induction of cPOD. A similar effect was obtained with the widely used elicitor, chitosan, which also induced cPODs with pI 5.3 and 5.7, which may be specifically related to pathogen defence. The differences reported here between biochemical properties of cPOD and iPOD and their differential induction during development and under specific treatments implicate that they are involved in specific and different physiological processes. PMID:22760472

  6. Systemic Resistance Induced by Volatile Organic Compounds Emitted by Plant Growth-Promoting Fungi in Arabidopsis thaliana

    OpenAIRE

    Naznin, Hushna Ara; Kiyohara, Daigo; Kimura, Minako; Miyazawa, Mitsuo; Shimizu, Masafumi; Hyakumachi, Mitsuro

    2014-01-01

    Volatile organic compounds (VOC) were extracted and identified from plant growth-promoting fungi (PGPF), Phoma sp., Cladosporium sp. and Ampelomyces sp., using gas chromatography–mass spectrometry (GC-MS). Among the three VOC extracted, two VOC blends (emitted from Ampelomyces sp. and Cladosporium sp.) significantly reduced disease severity in Arabidopsis plants against Pseudomonas syringae pv. tomato DC3000 (Pst). Subsequently, m-cresol and methyl benzoate (MeBA) were identified as major act...

  7. Soil microbial biomass and root growth in Bt and non-Bt cotton

    Science.gov (United States)

    Tan, D. K. Y.; Broughton, K.; Knox, O. G.; Hulugalle, N. R.

    2012-04-01

    The introduction of transgenic Bacillus thuringiensis (Bt) cotton (Gossypium hirsutum L.) has had a substantial impact on pest management in the cotton industry. While there has been substantial research done on the impact of Bt on the above-ground parts of the cotton plant, less is known about the effect of Bt genes on below ground growth of cotton and soil microbial biomass. The aim of this research was to test the hypothesis that Bt [Sicot 80 BRF (Bollgard II Roundup Ready Flex®)] and non-Bt [Sicot 80 RRF (Roundup Ready Flex®)] transgenic cotton varieties differ in root growth and root turnover, carbon indices and microbial biomass. A field experiment was conducted in Narrabri, north-western NSW. The experimental layout was a randomised block design and used minirhizotron and core break and root washing methods to measure cotton root growth and turnover during the 2008/09 season. Root growth in the surface 0-0.1 m of the soil was measured using the core break and root washing methods, and that in the 0.1 to 1 m depth was measured with a minirhizotron and an I-CAP image capture system. These measurements were used to calculate root length per unit area, root carbon added to the soil through intra-seasonal root death, carbon in roots remaining at the end of the season and root carbon potentially added to the soil. Microbial biomass was also measured using the ninhydrin reactive N method. Root length densities and length per unit area of non-Bt cotton were greater than Bt cotton. There were no differences in root turnover between Bt and non-Bt cotton at 0-1 m soil depth, indicating that soil organic carbon stocks may not be affected by cotton variety. Cotton variety did not have an effect on soil microbial biomass. The results indicate that while there are differences in root morphology between Bt and non-Bt cotton, these do not change the carbon turnover dynamics in the soil.

  8. Plant root growth and the marginal value theorem

    OpenAIRE

    McNickle, Gordon G.; Cahill, James F.

    2009-01-01

    All organisms must find and consume resources to live, and the strategies an organism uses when foraging can have significant impacts on their fitness. Models assuming optimality in foraging behavior, and which quantitatively account for the costs, benefits, and biological constraints of foraging, are common in the animal literature. Plant ecologists on the other hand have rarely adopted an explicit framework of optimality with respect to plant root foraging. Here, we show with a simple exper...

  9. Tree growth and management in Ugandan agroforestry systems: effects of root pruning on tree growth and crop yield

    OpenAIRE

    Wajja-Musukwe, Tellie-Nelson; Wilson, Julia; Sprent, Janet I.; Ong, Chin K.; Deans, J. Douglas; Okorio, John

    2008-01-01

    Tree root pruning is a potential tool for managing below-ground competition when trees and crops are grown together in agroforestry systems. This study investigates its effects on growth and root distribution of Alnus acuminata (HB & K), Casuarina equisetifolia (L), Grevillea robusta (A. Cunn. ex R. Br), Maesopsis eminii (Engl.), and Markhamia lutea (Benth.) K. Schum. and on yield of adjacent crops in sub-humid Uganda. The trees were 3 years old at the commencement of the study, and most spec...

  10. Root growth of tomato seedlings intensified by humic substances from peat bogs

    Directory of Open Access Journals (Sweden)

    Alexandre Christofaro Silva

    2011-10-01

    Full Text Available Peats are an important reserve of humified carbon in terrestrial ecosystems. The interest in the use of humic substances as plant growth promoters is continuously increasing. The objective of this study was to evaluate the bioactivity of alkaline soluble humic substances (HS, humic (HA and fulvic acids (FA isolated from peats with different decomposition stages of organic matter (sapric, fibric and hemic in the Serra do Espinhaço Meridional, state of Minas Gerais. Dose-response curves were established for the number of lateral roots growing from the main plant axis of tomato seedlings. The bioactivity of HA was greatest (highest response in lateral roots at lowest concentration while FA did not intensify root growth. Both HS and HA stimulated root hair formation. At low concentrations, HS and HA induced root hair formation near the root cap, a typical hormonal imbalance effect in plants. Transgenic tomato with reporter gene DR5::GUS allowed the observation that the auxin-related signalling pathway was involved in root growth promotion by HA.

  11. EFFECTS OF GROWTH REGULATORS ON ROOTING CUTTINGS OF SYRINGA (PHILADELPHUS L.,PHILADELPHACEAE

    Directory of Open Access Journals (Sweden)

    Grekova I. V.

    2015-01-01

    Full Text Available Increased range of Syringa in landscaping is a topical issue. They are very decorative shrubs, more and more widely used in landscape design. Study of vegetative propagation of plants, with the use of growth regulators, was conducted to identify the most perspective stimulator and to reduce the terms of the finished product. Syringa refers to bad rooting cultures. However, the methods of green propagation of cuttings with the use of growth stimulators not only propagate a culture, but also increase the yield of landing products. The article considers the technology propagation by cuttings of this promising shrub. It also shows the effect of growth stimulators: radifarma and HB-101, used for soaking of cuttings. According to the research, we have found an apparent benefits effect of the processing of cuttings with the stimulators on growth and development of root system. The analysis of the tables of rooting rate of cuttings shows the positive development of cuttings in the processing of the growth regulators. We have obtained the experimental data allowing to define which varieties distinguished by the greatest rooting and duration rooting among all the studied cultivars. Thus, the studies show that the use of growth stimulators with propagation of Syringa cuttings is an effective way of reproduction

  12. Photorespiratory Bypasses Lead to Increased Growth in Arabidopsis thaliana: Are Predictions Consistent with Experimental Evidence?

    Science.gov (United States)

    Basler, Georg; Küken, Anika; Fernie, Alisdair R; Nikoloski, Zoran

    2016-01-01

    Arguably, the biggest challenge of modern plant systems biology lies in predicting the performance of plant species, and crops in particular, upon different intracellular and external perturbations. Recently, an increased growth of Arabidopsis thaliana plants was achieved by introducing two different photorespiratory bypasses via metabolic engineering. Here, we investigate the extent to which these findings match the predictions from constraint-based modeling. To determine the effect of the employed metabolic network model on the predictions, we perform a comparative analysis involving three state-of-the-art metabolic reconstructions of A. thaliana. In addition, we investigate three scenarios with respect to experimental findings on the ratios of the carboxylation and oxygenation reactions of Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO). We demonstrate that the condition-dependent growth phenotypes of one of the engineered bypasses can be qualitatively reproduced by each reconstruction, particularly upon considering the additional constraints with respect to the ratio of fluxes for the RuBisCO reactions. Moreover, our results lend support for the hypothesis of a reduced photorespiration in the engineered plants, and indicate that specific changes in CO2 exchange as well as in the proxies for co-factor turnover are associated with the predicted growth increase in the engineered plants. We discuss our findings with respect to the structure of the used models, the modeling approaches taken, and the available experimental evidence. Our study sets the ground for investigating other strategies for increase of plant biomass by insertion of synthetic reactions. PMID:27092301

  13. Toxic effects of Cu2+ on growth, nutrition, root morphology, and distribution of Cu in roots of Sabi grass

    International Nuclear Information System (INIS)

    Sabi grass (Urochloa mosambicensis (Hack.) Dandy) (a C4 species of Poaceae) is commonly used to revegetate disturbed sites in low-rainfall environments, but comparatively little is known regarding copper (Cu) toxicity in this species. A dilute nutrient solution culture experiment was conducted for 10 d to examine the effects of elevated Cu2+ activities ({Cu2+}) on the growth of Sabi grass. Growth was inhibited by high Cu in solution, with a 50% reduction in the relative fresh mass occurring at 1.0 μM {Cu2+} for the roots and 1.2 μM {Cu2+} for the shoots. In solutions containing 1.2-1.9 μM {Cu2+}, many of the roots ruptured due to the tearing and separation of the rhizodermis and outer cortex from the underlying tissues. Transmission electron microscopy revealed that Cu-rich deposits were found to accumulate predominantly within vacuoles. Due to limited translocation of Cu from the roots to the shoots, phytotoxicity is likely to be more of a problem in remediation of Cu-toxic sites than is Cu toxicity of fauna consuming the above-ground biomass.

  14. The WUSCHEL Related Homeobox Protein WOX7 Regulates the Sugar Response of Lateral Root Development in Arabidopsis thaliana.

    Science.gov (United States)

    Kong, Danyu; Hao, Yueling; Cui, Hongchang

    2016-02-01

    Sugars promote lateral root formation at low levels but become inhibitory at high C/N or C/P ratios. How sugars suppress lateral root formation is unclear, however. Here we report that WOX7, a member of the WUSCHEL related homeobox (WOX) family transcription factors, inhibits lateral root development in a sugar-dependent manner. The number of lateral root primordia increased in wox7 mutants but decreased in plants over-expressing WOX7. Plants expressing the WOX7-VP16 fusion protein produced even more lateral roots than wox7, suggesting that WOX7 acts as a transcriptional repressor in lateral root development. WOX7 is expressed at all stages of lateral root development, but it is primarily involved in lateral root initiation. Consistent with this, the wox7 mutant had a higher mitotic activity only at early stages of lateral root development. Further studies suggest that WOX7 regulates lateral root development through direct repression of cell cycle genes, particularly CYCD6;1. WOX7 expression was enhanced by sugar, reduced by auxin, but did not respond to salt and mannitol. In the wox7 mutant, the effect of sugar on lateral root formation was mitigated. These results together suggest that WOX7 plays an important role in coupling the lateral root development program and sugar status in plants. PMID:26621542

  15. Genetic analysis of ectopic growth suppression during planar growth of integuments mediated by the Arabidopsis AGC protein kinase UNICORN

    Directory of Open Access Journals (Sweden)

    Enugutti Balaji

    2013-01-01

    Full Text Available Abstract Background The coordination of growth within a tissue layer is of critical importance for tissue morphogenesis. For example, cells within the epidermis undergo stereotypic cell divisions that are oriented along the plane of the layer (planar growth, thereby propagating the layered epidermal structure. Little is known about the developmental control that regulates such planar growth in plants. Recent evidence suggested that the Arabidopsis AGC VIII protein kinase UNICORN (UCN maintains planar growth by suppressing the formation of ectopic multicellular protrusions in several floral tissues including integuments. In the current model UCN controls this process during integument development by directly interacting with the ABERRANT TESTA SHAPE (ATS protein, a member of the KANADI (KAN family of transcription factors, thereby repressing its activity. Here we report on the further characterization of the UCN mechanism. Results Phenotypic analysis of flowers of ucn-1 plants impaired in floral homeotic gene activity revealed that any of the four floral whorls could produce organs carrying ucn-1 protrusions. The ectopic outgrowths of ucn integuments did not accumulate detectable signals of the auxin and cytokinin reporters DR5rev::GFP and ARR5::GUS, respectively. Furthermore, wild-type and ucn-1 seedlings showed similarly strong callus formation upon in vitro culture on callus-inducing medium. We also show that ovules of ucn-1 plants carrying the dominant ats allele sk21-D exhibited more pronounced protrusion formation. Finally ovules of ucn-1 ett-1 double mutants and ucn-1 ett-1 arf4-1 triple mutants displayed an additive phenotype. Conclusions These data deepen the molecular insight into the UCN-mediated control of planar growth during integument development. The presented evidence indicates that UCN downstream signaling does not involve the control of auxin or cytokinin homeostasis. The results also reveal that UCN interacts with ATS

  16. The Effect of Chitosan and Sodium Alginate on the Root Growth and Enzyme Activity of Soybean

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The resaerch examined the effect of the two oceanic materials as coating materials on the soybean growth. The results showed chitosan and sodium alginate seed coating can enhance the growth of seedling root,increase the nodule mumber,root activity and the growth of underground. The suggested coating ratios were 0. 5~ 1.0g/kgseed,the same as chitosan. The two materials could increase the contents of CAT and NR in soybean leaves ,decrease the contents of POD in soybean leaves.

  17. Effects of Soil Water Content on Cotton Root Growth and Distribution Under Mulched Drip Irrigation

    Institute of Scientific and Technical Information of China (English)

    HU Xiao-tang; CHEN Hu; WANG Jing; MENG Xiao-bin; CHEN Fu-hong

    2009-01-01

    The relation between soil water content and the growth of cotton root was studied for the scheme of field water and cotton yield under mulched drip irrigation.Based on the field experiments,three treatments of soil water content were conducted with 90%θf,75%θf,and 60%θf (θf is field water capacity).Cotton roots and root-shoot ratio were studied with digging method,and the soil moisture was observed with TDR (time domain reflector),and cotton yield was measured.The results indicated that the growth of cotton root accorded with Logistic growth curve in the three treatments,the cotton root grew quickly and its weight was very high under 75%θf because of the suitable soil water condition,while grew slowly and its weight was lower under 90%θf due to water moisture beyond the suitable condition,and the root weight was in between under 60%θf.For the three water treatments,the cotton root weight decreased with soil depth,and decreased more significantly in deeper soil layer with the soil moisture increasing.And the ratio of cotton root weight in 0-30 cm soil layer to the total root weight was the highest under 75%θf.The cotton root system was distributed mainly in the soil of narrow row and wide row mulched with plastic film,and little in the soil outside plastic film.The weight of cotton root was the highest in the soil of narrow row or wide row mulched with plastic film under 75%θf.Root-shoot ratio decreased with the soil moisture increasing.The soil water content affected cotton yields,and cotton yield was the highest under 75%θf.The higher soil moisture level is unfavorable to the growth of cotton root system and yield of cotton under mulched drip irrigation.

  18. Two Hydroxyproline Galactosyltransferases, GALT5 and GALT2, Function in Arabinogalactan-Protein Glycosylation, Growth and Development in Arabidopsis.

    Directory of Open Access Journals (Sweden)

    Debarati Basu

    Full Text Available Hydroxyproline-O-galactosyltransferase (GALT initiates O-glycosylation of arabinogalactan-proteins (AGPs. We previously characterized GALT2 (At4g21060, and now report on functional characterization of GALT5 (At1g74800. GALT5 was identified using heterologous expression in Pichia and an in vitro GALT assay. Product characterization showed GALT5 specifically adds galactose to hydroxyproline in AGP protein backbones. Functions of GALT2 and GALT5 were elucidated by phenotypic analysis of single and double mutant plants. Allelic galt5 and galt2 mutants, and particularly galt2 galt5 double mutants, demonstrated lower GALT activities and reductions in β-Yariv-precipitated AGPs compared to wild type. Mutant plants showed pleiotropic growth and development phenotypes (defects in root hair growth, root elongation, pollen tube growth, flowering time, leaf development, silique length, and inflorescence growth, which were most severe in the double mutants. Conditional mutant phenotypes were also observed, including salt-hypersensitive root growth and root tip swelling as well as reduced inhibition of pollen tube growth and root growth in response to β-Yariv reagent. These mutants also phenocopy mutants for an AGP, SOS5, and two cell wall receptor-like kinases, FEI1 and FEI2, which exist in a genetic signaling pathway. In summary, GALT5 and GALT2 function as redundant GALTs that control AGP O-glycosylation, which is essential for normal growth and development.

  19. Arabidopsis DREB1B in transgenic Salvia miltiorrhiza increased tolerance to drought stress without stunting growth.

    Science.gov (United States)

    Wei, Tao; Deng, Kejun; Gao, Yonghong; Liu, Yu; Yang, Meiling; Zhang, Lipeng; Zheng, Xuelian; Wang, Chunguo; Song, Wenqin; Chen, Chengbin; Zhang, Yong

    2016-07-01

    Multiple stress response genes are controlled by transcription factors in a coordinated manner; therefore, these factors can be used for molecular plant breeding. CBF1/DREB1B, a known stress-inducible gene, was isolated from Arabidopsis thaliana and introduced into Salvia miltiorrhiza under the control of the CaMV35S or RD29A promoter. Under drought stress, relative water content, chlorophyll content, and the net photosynthetic rate were observed to be higher in the transgenic lines than in the wild type (WT). Moreover, O2(-) and H2O2 accumulation was observed to be lower in the transgenic lines. Additional analyses revealed that the AtDREB1B transgenic plants generally displayed lesser malondialdehyde (MDA) but higher superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) activities than the WT under drought stress. Quantitative real-time polymerase chain reaction of a subset of genes involved in photosynthesis, stress response, carbohydrate metabolism, and cell protection further verified that AtDREB1B could enhance tolerance to drought by activating different downstream DREB/CBF genes in the transgenic plants. Furthermore, no growth inhibition was detected in transgenic S. miltiorrhiza plants that expressed AtDREB1B driven by either the constitutive CaMV35S promoter or the stress-inducible RD29A promoter. Together, these results suggest that AtDREB1B is a good candidate gene for increasing drought tolerance in transgenic S. miltiorrhiza. PMID:27002402

  20. Fruit Growth in Arabidopsis Occurs via DELLA-Dependent and DELLA-Independent Gibberellin Responses[W][OA

    Science.gov (United States)

    Fuentes, Sara; Ljung, Karin; Sorefan, Karim; Alvey, Elizabeth; Harberd, Nicholas P.; Østergaard, Lars

    2012-01-01

    Fruit growth and development depend on highly coordinated hormonal activities. The phytohormone gibberellin (GA) promotes growth by inducing degradation of the growth-repressing DELLA proteins; however, the extent to which DELLA proteins contribute to GA-mediated gynoecium and fruit development remains to be clarified. Here, we provide an in-depth characterization of the role of DELLA proteins in Arabidopsis thaliana fruit growth. We show that DELLA proteins are key regulators of reproductive organ size and important for ensuring optimal fertilization. We demonstrate that the seedless fruit growth (parthenocarpy) observed in della mutants can be directly attributed to the constitutive activation of GA signaling. It has been known for >75 years that another hormone, auxin, can induce formation of seedless fruits. Using mutants with complete lack of DELLA activity, we show here that auxin-induced parthenocarpy occurs entirely through GA signaling in Arabidopsis. Finally, we uncover the existence of a DELLA-independent GA response that promotes fruit growth. This response requires GIBBERELLIN-INSENSITIVE DWARF1–mediated GA perception and a functional 26S proteasome and involves the basic helix-loop-helix protein SPATULA as a key component. Taken together, our results describe additional complexities in GA signaling during fruit development, which may be particularly important to optimize the conditions for successful reproduction. PMID:23064323

  1. Sensitivity of root-knot nematodes to gamma irradiation, salinity and plant growth regulator, cycocel

    International Nuclear Information System (INIS)

    The experiment was carried out at the experimental station of the faculty of agriculture, Menoufia Univ. To determine the sensitivity of root-knot nematode, Meloidogyne Javanica infecting tomato plants exposed to different doses of gamma irradiation 0,20,40,60,80 Gy, salinity levels 0. 1000, 2000, 4000 ppm and the plant growth regulator cycocel 0,200 ppm. Treated seeds were planted clay pots and salinity levels and cycocel concentrations were applied. Fresh weights and nematode populations were computed 3 months after application. Results indicated that 20 Gy, 1000 ppm salinity and cycocel gave the highest fresh weight of shoots and roots. The developmental stages and egg-laying females of nematode decreased by the increasing of irradiation dose and salinity levels. Root-knot galls decreased with 40 and 60 Gy, while significant increase was observed with 0 and 80 Gy, salinity levels decreased root galls. Cycocel decreased nematode population, egg-lying females and root-knot galls

  2. Tooth root growth impairment after mantle radiation in long-term survivors of Hodgkin's disease

    International Nuclear Information System (INIS)

    The tooth root growth impairment that resulted from 35 to 37 Gy mantle port radiation in 47 long-term survivors of childhood Hodgkin's disease was quantified and related to specific age groups and categories of teeth. Root measurements of the mandibular permanent canines, first and second premolars, and first and second molars were made from sequential panoramic radiographs taken at the time of radiation therapy and after the closure of root apexes. The severity of root growth impairment was greatest in patients who received radiation during the early stages of odontogenesis. With later stages of odontogenesis, and as the age increased at the time of treatment, less impairment occurred. The potential difficulties of using repeated panoramic radiographs to assess tooth lengths in longitudinal studies also were discussed

  3. Root secretion stimulating ash growth in larch-ash mixed forest

    Institute of Scientific and Technical Information of China (English)

    吴俊民; 刘广平; 王晓水; 吴保国

    2000-01-01

    Allelopathic effect of larch (Larix gmelini ) on the ash growth (Fraximus mandshurica) was studied in artificial cultivation tests. The results revealed that the larch root secretion obviously stimulated the ash growth. In order to determine the main stimulation allelochemicals, the chemical composition was analyzed. By contrasting the contents of carbohydrate and aminoacid in root secretion of larch and ash, it was concluded that the carbohydrate and aminoacid were not important stimulation allelochemicals. The organic acid and other components in root secretion of larch and ash were analyzed by GC and GC-MS analysis. The sand culture tests were carried out with selected model compounds. The results showed that benzeneacetic acid, benzenepropionic acid and phenolic acids in root secretion of larch were the main stimulation allelochemicals.

  4. [Level nitric oxide (NO) and growth of roots of etiolated pea seedlings].

    Science.gov (United States)

    Glian'ko, A K; Ishchenko, A A

    2013-01-01

    Data regarding the interrelation of nitric oxide (NO) content in roots of 3-day-old etiolated pea seedlings and their growth under different concentrations of N-containing compounds were obtained. The concentration of exogenous compounds (sodium nitroprusside SNP, KNO3, NaNO2, L-arginine) rendering an inhibiting effect on the growth of roots were established, and the NO content in roots was determined at these concentration. It was shown that the inhibition of growth and highest NO content in the roots was determined with SNP (4 mM) and NaNO2 (2 mM) during 24 h exposition of seedlings. This dependence was not established in combinations with KNO3 (20 mM) and L-arginine (4 mM). We established that a NO scavenger, hemoglobin (4 μM), fully or partially removed the toxic effect of SNP, nitrate, and nitrite on growth. The effect of NO on the growth and the participation of N-containing compounds in generation of NO in roots of pea seedlings is discussed. PMID:25518555

  5. Radiomimetic effect of cisplatin on cucumber root development: the relationship between cell division and cell growth

    International Nuclear Information System (INIS)

    Cisplatin [DDP, cis-dichlorodiammine platinum (II)], a strong cytostatic and antineoplastic agent, was tested on seedlings of cucumber Cucumis sativus L. for its general effect on root development and its particular effects on root cell division and cell growth. DDP was characterized as a radiomimetic compound since both DDP (1·3 × 10-5 M) and γ-irradiation (2·5-10 kGy) drastically and irreversibly stopped development of embryonic lateral root primordia (LRPs) in the radicle by inhibiting both mitotic activity and cell growth. In 20% of the LRPs of DDP-treated roots, cells did not divide at all. Dividing cells completed no more than two cell cycles. These effects were specific because when DDP was available to the roots only at the onset of cell division, cell proliferation and cell growth were similar to that produced by constant incubation. Neither DDP nor γ-irradiation affected non-meristematic cell elongation. It was concluded that cell growth of meristematic cells is closely related to cell division. However, non-meristematic cell growth is independent of DNA damage. This suggests DDP as a tool to reveal these autonomous processes in plants development and to detect tissue compartments in mature plant embryos which contain potentially non-meristematic cells. (author)

  6. Spatial Regulation of Root Growth: Placing the Plant TOR Pathway in a Developmental Perspective

    Directory of Open Access Journals (Sweden)

    Adam Barrada

    2015-08-01

    Full Text Available Plant cells contain specialized structures, such as a cell wall and a large vacuole, which play a major role in cell growth. Roots follow an organized pattern of development, making them the organs of choice for studying the spatio-temporal regulation of cell proliferation and growth in plants. During root growth, cells originate from the initials surrounding the quiescent center, proliferate in the division zone of the meristem, and then increase in length in the elongation zone, reaching their final size and differentiation stage in the mature zone. Phytohormones, especially auxins and cytokinins, control the dynamic balance between cell division and differentiation and therefore organ size. Plant growth is also regulated by metabolites and nutrients, such as the sugars produced by photosynthesis or nitrate assimilated from the soil. Recent literature has shown that the conserved eukaryotic TOR (target of rapamycin kinase pathway plays an important role in orchestrating plant growth. We will summarize how the regulation of cell proliferation and cell expansion by phytohormones are at the heart of root growth and then discuss recent data indicating that the TOR pathway integrates hormonal and nutritive signals to orchestrate root growth.

  7. The effects of cotton root exudates on the growth and development of Verticillium dahliae

    Institute of Scientific and Technical Information of China (English)

    Yuxiang WU; Weiping FANG; Shuijin ZHU; Kuiying JIN; Daofan JI

    2008-01-01

    The effects of upland cotton root exudates on the growth and development of Verticillium dahliae were studied, through the compared analysis of the root exudates components between the resistant and suscept-ive cotton materials, using a pair of resistant and sus-ceptive isogenic lines to Verticillium wilt, Z5629 and Z421, as well as 4 other upland cotton cultivars with different resistant levels of Verticillium wilt. The results showed that the amino acids in the root exudates of the resistant cultivars were much less than that of the sus-ceptible ones. Compared with the susceptible ones, there were a lack of aspartic acid, threonine, glutamic acid, alanine, isoleucine, leucine, phenylalanine, lysine and proline in the root exudates from the resistant cul-tivars. On the contrary, arginine was lacking in the sus-ceptive cultivars. The saccharide types in the root exudates were no different between the two kinds of cultivars, but the contents of glucose, fructose and suc-rose in the root exudates of the susceptible varieties were much higher than those in the resistant ones. The experiment of Verticillium dahliae culture showed that the cotton root exudates from resistant cultivars can effectively restrain the spore germination and mycelium growth of Verticillium dahliae, and the argi-nine was the leading amino acid in this inhibitory action, besides the nutrition of the root exudates. However, the cotton root exudates from the susceptive cotton cultivars can improve the growth and develop-ment of Verticillium dahliae effectively; among the amino acid in the exudates, alanine was the most active one in this stimulating function.

  8. Transcription of DWARF4 plays a crucial role in auxin-regulated root elongation in addition to brassinosteroid homeostasis in Arabidopsis thaliana.

    Directory of Open Access Journals (Sweden)

    Yuya Yoshimitsu

    Full Text Available The expression of DWARF4 (DWF4, which encodes a C-22 hydroxylase, is crucial for brassinosteroid (BR biosynthesis and for the feedback control of endogenous BR levels. To advance our knowledge of BRs, we examined the effects of different plant hormones on DWF4 transcription in Arabidopsis thaliana. Semi-quantitative reverse-transcriptase PCR showed that the amount of the DWF4 mRNA precursor either decreased or increased, similarly with its mature form, in response to an exogenously applied bioactive BR, brassinolide (BL, and a BR biosynthesis inhibitor, brassinazole (Brz, respectively. The response to these chemicals in the levels of β-glucuronidase (GUS mRNA and its enzymatic activity is similar to the response of native DWF4 mRNA in DWF4::GUS plants. Contrary to the effects of BL, exogenous auxin induced GUS activity, but this enhancement was suppressed by anti-auxins, such as α-(phenylethyl-2-one-IAA and α-tert-butoxycarbonylaminohexyl-IAA, suggesting the involvement of SCF(TIR1-mediated auxin signaling in auxin-induced DWF4 transcription. Auxin-enhanced GUS activity was observed exclusively in roots; it was the most prominent in the elongation zones of both primary and lateral roots. Furthermore, auxin-induced lateral root elongation was suppressed by both Brz application and the dwf4 mutation, and this suppression was rescued by BL, suggesting that BRs act positively on root elongation under the control of auxin. Altogether, our results indicate that DWF4 transcription plays a novel role in the BR-auxin crosstalk associated with root elongation, in addition to its role in BR homeostasis.

  9. Ethylene regulates root growth through effects on auxin biosynthesis and transport-dependent auxin distribution

    OpenAIRE

    Ruzicka, Kamil; Ljung, Karin; Vanneste, Steffen; Podhorská, Radka; Beeckman, Tom; Friml, Jiri; Benkova, Eva

    2007-01-01

    In plants, each developmental process integrates a network of signaling events that are regulated by different phytohormones, and interactions among hormonal pathways are essential to modulate their effect. Continuous growth of roots results from the postembryonic activity of cells within the root meristem that is controlled by the coordinated action of several phytohormones, including auxin and ethylene. Although their interaction has been studied intensively, the molecular and cellular mech...

  10. Live substrate positively affects root growth and stolon direction in the woodland strawberry, Fragaria vesca

    OpenAIRE

    Waters, Erica M.; Watson, Maxine A.

    2015-01-01

    Studies of clonal plant foraging generally focus on growth responses to patch quality once rooted. Here we explore the possibility of true plant foraging; the ability to detect and respond to patch resource status prior to rooting. Two greenhouse experiments were conducted to investigate the morphological changes that occur when individual daughter ramets of Fragaria vesca (woodland strawberry) were exposed to air above live (non-sterilized) or dead (sterilized) substrates. Contact between da...

  11. Effect of soil moisture deficit in the upper root zone on growth and yield of soybeans

    Energy Technology Data Exchange (ETDEWEB)

    Anwar-ul-Haq; Brown, D.A.

    Soybean producers in Arkansas frequently are confronted with drought conditions which limit yields. These moisture deficit periods result in decreased water and nutrient absorption which adversely affects root growth and distribution within the soil profile, bloom set, and seed-pod retention. Producers have attempted to eliminate this problem by irrigation, by the use of drought tolerant cultivars, and by chiseling to provide for greater root penetration into the subsoil.

  12. Rooting behaviour, polyphenol oxidase activity, and biochemical changes in grape rootstocks at different growth stages

    OpenAIRE

    SOMKUWAR, Ramhari G.; BONDAGE, Devanand D.; SURANGE, Manisha S.; Ramteke, Sahadeo D.

    2011-01-01

    Four grape rootstocks belonging to different Vitis species were planted in September. Rooting behaviour, polyphenol oxidase (PPO; EC 1.14.18.1) activity and biochemical parameters were studied at different growth stages after planting the cuttings in polythene bags. Significant differences were recorded for rooting success among the different rootstocks, with the maximum sprouting percentage determined in the Freedom rootstock. The highest variation in PPO activity was also recorded in Freedo...

  13. Multiple impacts of loss of plastidic phosphatidylglycerol biosynthesis on photosynthesis during seedling growth of Arabidopsis

    Directory of Open Access Journals (Sweden)

    Koichi eKobayashi

    2016-03-01

    Full Text Available Phosphatidylglycerol (PG is the only major phospholipid in the thylakoid membrane in cyanobacteria and plant chloroplasts. Although PG accounts only for ~10% of total thylakoid lipids, it plays indispensable roles in oxygenic photosynthesis. In contrast to the comprehensive analyses of PG-deprived mutants in cyanobacteria, in vivo roles of PG in photosynthesis during plant growth remain elusive. In this study, we characterized the photosynthesis of an Arabidopsis thaliana T-DNA insertional mutant (pgp1-2, which lacks plastidic PG biosynthesis. In the pgp1-2 mutant, energy transfer from antenna pigments to the photosystem II (PSII reaction center was severely impaired, which resulted in low photochemical efficiency of PSII. Unlike in the wild type, in pgp1-2, the PSII complexes were susceptible to photodamage by red light irradiation. Manganese ions were mostly dissociated from protein systems in pgp1-2, with oxygen-evolving activity of PSII absent in the mutant thylakoids. The oxygen-evolving complex may be disrupted in pgp1-2, which may accelerate the photodamage to PSII by red light. On the acceptor side of the mutant PSII, decreased electron-accepting capacity was observed along with impaired electron transfer. Although the reaction center of PSI was relatively active in pgp1-2 compared to the severe impairment in PSII, the cyclic electron transport was dysfunctional. Chlorophyll fluorescence analysis at 77K revealed that PG may not be needed for the self-organization of the macromolecular protein network in grana thylakoids but is essential for the assembly of antenna-reaction center complexes. Our data clearly show that thylakoid glycolipids cannot substitute for the role of PG in photosynthesis during plant growth.

  14. Multiple Impacts of Loss of Plastidic Phosphatidylglycerol Biosynthesis on Photosynthesis during Seedling Growth of Arabidopsis

    Science.gov (United States)

    Kobayashi, Koichi; Endo, Kaichiro; Wada, Hajime

    2016-01-01

    Phosphatidylglycerol (PG) is the only major phospholipid in the thylakoid membrane in cyanobacteria and plant chloroplasts. Although PG accounts only for ~10% of total thylakoid lipids, it plays indispensable roles in oxygenic photosynthesis. In contrast to the comprehensive analyses of PG-deprived mutants in cyanobacteria, in vivo roles of PG in photosynthesis during plant growth remain elusive. In this study, we characterized the photosynthesis of an Arabidopsis thaliana T-DNA insertional mutant (pgp1-2), which lacks plastidic PG biosynthesis. In the pgp1-2 mutant, energy transfer from antenna pigments to the photosystem II (PSII) reaction center was severely impaired, which resulted in low photochemical efficiency of PSII. Unlike in the wild type, in pgp1-2, the PSII complexes were susceptible to photodamage by red light irradiation. Manganese ions were mostly dissociated from protein systems in pgp1-2, with oxygen-evolving activity of PSII absent in the mutant thylakoids. The oxygen-evolving complex may be disrupted in pgp1-2, which may accelerate the photodamage to PSII by red light. On the acceptor side of the mutant PSII, decreased electron-accepting capacity was observed along with impaired electron transfer. Although the reaction center of PSI was relatively active in pgp1-2 compared to the severe impairment in PSII, the cyclic electron transport was dysfunctional. Chlorophyll fluorescence analysis at 77K revealed that PG may not be needed for the self-organization of the macromolecular protein network in grana thylakoids but is essential for the assembly of antenna-reaction center complexes. Our data clearly show that thylakoid glycolipids cannot substitute for the role of PG in photosynthesis during plant growth. PMID:27047516

  15. Multiple Impacts of Loss of Plastidic Phosphatidylglycerol Biosynthesis on Photosynthesis during Seedling Growth of Arabidopsis.

    Science.gov (United States)

    Kobayashi, Koichi; Endo, Kaichiro; Wada, Hajime

    2016-01-01

    Phosphatidylglycerol (PG) is the only major phospholipid in the thylakoid membrane in cyanobacteria and plant chloroplasts. Although PG accounts only for ~10% of total thylakoid lipids, it plays indispensable roles in oxygenic photosynthesis. In contrast to the comprehensive analyses of PG-deprived mutants in cyanobacteria, in vivo roles of PG in photosynthesis during plant growth remain elusive. In this study, we characterized the photosynthesis of an Arabidopsis thaliana T-DNA insertional mutant (pgp1-2), which lacks plastidic PG biosynthesis. In the pgp1-2 mutant, energy transfer from antenna pigments to the photosystem II (PSII) reaction center was severely impaired, which resulted in low photochemical efficiency of PSII. Unlike in the wild type, in pgp1-2, the PSII complexes were susceptible to photodamage by red light irradiation. Manganese ions were mostly dissociated from protein systems in pgp1-2, with oxygen-evolving activity of PSII absent in the mutant thylakoids. The oxygen-evolving complex may be disrupted in pgp1-2, which may accelerate the photodamage to PSII by red light. On the acceptor side of the mutant PSII, decreased electron-accepting capacity was observed along with impaired electron transfer. Although the reaction center of PSI was relatively active in pgp1-2 compared to the severe impairment in PSII, the cyclic electron transport was dysfunctional. Chlorophyll fluorescence analysis at 77K revealed that PG may not be needed for the self-organization of the macromolecular protein network in grana thylakoids but is essential for the assembly of antenna-reaction center complexes. Our data clearly show that thylakoid glycolipids cannot substitute for the role of PG in photosynthesis during plant growth. PMID:27047516

  16. Jasmonate controls late development stages of petal growth in Arabidopsis thaliana.

    Science.gov (United States)

    Brioudes, Florian; Joly, Caroline; Szécsi, Judit; Varaud, Emilie; Leroux, Julie; Bellvert, Floriant; Bertrand, Cédric; Bendahmane, Mohammed

    2009-12-01

    In Arabidopsis, four homeotic gene classes, A, B, C and E, are required for the patterning of floral organs. However, very little is known about how the activity of these master genes is translated into regulatory processes leading to specific growth patterns and the formation of organs with specific shapes and sizes. Previously we showed that the transcript variant BPEp encodes a bHLH transcription factor that is involved in limiting petal size by controlling post-mitotic cell expansion. Here we show that the phytohormone jasmonate is required for control of BPEp expression. Expression of BPEp was negatively regulated in opr3 mutant flowers that are deficient in jasmonate synthesis. Moreover, the expression of BPEp was restored in opr3 flowers following exogenous jasmonate treatments. Expression of the second transcript variant BPEub, which originates from the same gene as BPEp via an alternative splicing event, was not affected, indicating that BPEp accumulation triggered by jasmonate occurs at the post-transcriptional level. Consistent with these data, opr3 exhibited an increase in petal size as a result of increased cell size, as well as a modified vein pattern, phenotypes that are similar to those of the bpe-1 mutant. Furthermore, exogenous treatments with jasmonate rescued petal phenotypes associated with loss of function of OPR3. Our data demonstrate that jasmonate signaling downstream of OPR3 is involved in the control of cell expansion and in limiting petal size, and that BPEp is a downstream target that functions as a component mediating jasmonate signaling during petal growth. PMID:19765234

  17. Effects of Lanthanum on Root Growth and Senescence of GF43(Prunus domestica) Plantlet in Vitro

    Institute of Scientific and Technical Information of China (English)

    宋卫平; 顾福根; 于佳; 沈叶; 溪群华; 刘佳佳

    2004-01-01

    The effect and the action mechanism of lanthanum on GF43 plantlet in vitro were studied. The results of experiments show that root growth rate and dry weight of GF43 by LaCl3 treatments increase. The activities of antioxidant enzymes in root system such as superoxide dismutase(SOD),catalase(CAT) and peroxidase(POD) apparently enhance. Moreover *O-2 and malond ialdehyde(MDA) contents and cell membrane permeability of GF43 are decreased by LaCl3. The relatively stable membrane structure of cell could also be maintained and the root ageing of GF43 plantlet in vitro delays.

  18. Analysis of Puerarin and Chemical Compositions Changes in Kudzu Root during Growth Period

    Directory of Open Access Journals (Sweden)

    Yiguo Zhao

    2014-01-01

    Full Text Available The kudzu root is one of the earliest medicinal plants listed in traditional Chinese medicine. In this paper, chemical compositions changes of kudzu roots from one year old to five years old were analyzed with respect to puerarin, acid-insoluble polysaccharides, acid-soluble polysaccharides, reducing sugar, protein, free amino acids, and lipid. In addition, the puerarin content was determined by high performance liquid chromatography (HPLC method. The results showed that acid-soluble polysaccharides content of kudzu root increased with each growth period. In contrast, the acid-insoluble polysaccharides decreased significantly. The contents of reducing sugar and puerarin in kudzu root decreased significantly during its growth period. Beyond that, the contents of protein, free amino acids, and lipid in kudzu root ranged from 31.8 to 45.8 g/kg, 2.21 to 4.33 g/kg, and 32.2 to 76.9 g/kg, respectively. The trend of protein content coincided with the total content of free amino acids, in contrast to lipid. This paper provides a set of data and the select of kudzu root for the processing and development of new products of kudzu root.

  19. Beneficial Microbes Affect Endogenous Mechanisms Controlling Root Development.

    Science.gov (United States)

    Verbon, Eline H; Liberman, Louisa M

    2016-03-01

    Plants have incredible developmental plasticity, enabling them to respond to a wide range of environmental conditions. Among these conditions is the presence of plant growth-promoting rhizobacteria (PGPR) in the soil. Recent studies show that PGPR affect Arabidopsis thaliana root growth and development by modulating cell division and differentiation in the primary root and influencing lateral root development. These effects lead to dramatic changes in root system architecture that significantly impact aboveground plant growth. Thus, PGPR may promote shoot growth via their effect on root developmental programs. This review focuses on contextualizing root developmental changes elicited by PGPR in light of our understanding of plant-microbe interactions and root developmental biology. PMID:26875056

  20. Reverse genetic characterization of two paralogous acetoacetyl CoA thiolase genes in Arabidopsis reveals their importance in plant growth and development

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Huanan; Song, Zhihong; Nikolau, Basil J.

    2012-03-31

    Acetoacetyl CoA thiolase (AACT, EC 2.3.1.9) catalyzes the condensation of two acetyl CoA molecules to form acetoacetyl CoA. Two AACT‐encoding genes, At5g47720 (AACT1) and At5g48230 (AACT2), were functionally identified in the Arabidopsis genome by direct enzymological assays and functional expression in yeast. Promoter::GUS fusion experiments indicated that AACT1 is primarily expressed in the vascular system and AACT2 is highly expressed in root tips, young leaves, top stems and anthers. Characterization of T‐DNA insertion mutant alleles at each AACT locus established that AACT2 function is required for embryogenesis and for normal male gamete transmission. In contrast, plants lacking AACT1 function are completely viable and show no apparent growth phenotypes, indicating that AACT1 is functionally redundant with respect to AACT2 function. RNAi lines that express reduced levels of AACT2 show pleiotropic phenotypes, including reduced apical dominance, elongated life span and flowering duration, sterility, dwarfing, reduced seed yield and shorter root length. Microscopic analysis reveals that the reduced stature is caused by a reduction in cell size and fewer cells, and male sterility is caused by loss of the pollen coat and premature degeneration of the tapetal cells. Biochemical analyses established that the roots of AACT2 RNAi plants show quantitative and qualitative alterations in phytosterol profiles. These phenotypes and biochemical alterations are reversed when AACT2 RNAi plants are grown in the presence of mevalonate, which is consistent with the role of AACT2 in generating the bulk of the acetoacetyl CoA precursor required for the cytosol‐localized, mevalonate‐derived isoprenoid biosynthetic pathway.

  1. Marfan syndrome in children and adolescents: predictive and prognostic value of aortic root growth for screening for aortic complications

    OpenAIRE

    Groenink, M; Rozendaal, L; Naeff, M.S.J.; Hennekam, R.C.M.; Hart, A.A.M.; Wall; Mulder, B.J.M.

    1998-01-01

    Objective—To assess and measure the diagnostic and prognostic value of individual aortic root growth in children and adolescents with Marfan syndrome.
Design—From 1983 to 1996, 250 children were screened for Marfan syndrome. Serial echocardiographic aortic root measurements of 123 children (57 Marfan, 66 control) were available for evaluation of aortic root growth. Aortic root diameters were correlated with body surface area. Based on individual growth of the aortic root a discrimination form...

  2. Influence of water stress on the percentage of active root and plant growth of soybean

    International Nuclear Information System (INIS)

    Two experiments have been carried out to obtain data on the influence of water stress on active root and plant growth. In the first experiment water stress treatment was conducted seven days before plants were harvested. In the second experiment water stress treatment was done, when the plants were 35 days old, with watering at 3, 6, 9 and 12 days intervals up to the time when the plants reached the age of 50 days. To determine the active root growth on 0-10 cm and 10-20 cm depths, 32P in the form of KH232PO4 carrier free solution was used. The data obtained show that water stress has a significant influence on active root and plant growth. (author)

  3. An Undergraduate Study of Two Transcription Factors that Promote Lateral Root Formation

    Science.gov (United States)

    Bargmann, Bastiaan O. R.; Birnbaum, Kenneth D.; Brenner, Eric D.

    2014-01-01

    We present a lab that enables students to test the role of genes involved in the regulation of lateral roots growth in the model plant "Arabidopsis thaliana." Here, students design an experiment that follows the effects of the hormone auxin on the stimulation of genes involved in the formation of lateral root initials. These genes, known…

  4. Impact of treated wastewater on growth, respiration and hydraulic conductivity of citrus root systems in light and heavy soils.

    Science.gov (United States)

    Paudel, Indira; Cohen, Shabtai; Shaviv, Avi; Bar-Tal, Asher; Bernstein, Nirit; Heuer, Bruria; Ephrath, Jhonathan

    2016-06-01

    Roots interact with soil properties and irrigation water quality leading to changes in root growth, structure and function. We studied these interactions in an orchard and in lysimeters with clay and sandy loam soils. Minirhizotron imaging and manual sampling showed that root growth was three times lower in the clay relative to sandy loam soil. Treated wastewater (TWW) led to a large reduction in root growth with clay (45-55%) but not with sandy loam soil (system. The phenology and physiology of root orders were studied in lysimeters. Soil type influenced diameter, specific root area, tissue density and cortex area similarly in all root orders, while TWW influenced these only in clay soil. Respiration rates were similar in both soils, and root hydraulic conductivity was severely reduced in clay soil. Treated wastewater increased respiration rate and reduced hydraulic conductivity of all root orders in clay but only of the lower root orders in sandy loam soil. Loss of hydraulic conductivity increased with root order in clay and clay irrigated with TWW. Respiration and hydraulic properties of all root orders were significantly affected by sodium-amended TWW in sandy loam soil. These changes in root order morphology, anatomy, physiology and hydraulic properties indicate rapid and major modifications of root systems in response to differences in soil type and water quality. PMID:27022106

  5. Soil contamination with silver nanoparticles reduces Bishop pine growth and ectomycorrhizal diversity on pine roots

    Energy Technology Data Exchange (ETDEWEB)

    Sweet, M. J., E-mail: m.sweet@derby.ac.uk [University of Derby, Environmental Sustainability Research Centre, College of Life and Natural Sciences (United Kingdom); Singleton, I. [Newcastle University, School of Biology (United Kingdom)

    2015-11-15

    Soil contamination by silver nanoparticles (AgNP) is of potential environmental concern but little work has been carried out on the effect of such contamination on ectomycorrhizal fungi (EMF). EMF are essential to forest ecosystem functions as they are known to enhance growth of trees by nutrient transfer. In this study, soil was experimentally contaminated with AgNP (0, 350 and 790 mg Ag/kg) and planted with Bishop pine seedlings. The effect of AgNP was subsequently measured, assessing variation in pine growth and ectomycorrhizal diversity associated with the root system. After only 1 month, the highest AgNP level had significantly reduced the root length of pine seedlings, which in turn had a small effect on above ground plant biomass. However, after 4 months growth, both AgNP levels utilised had significantly reduced both pine root and shoot biomass. For example, even the lower levels of AgNP (350 mg Ag/kg) soil, reduced fresh root biomass by approximately 57 %. The root systems of the plants grown in AgNP-contaminated soils lacked the lateral and fine root development seen in the control plants (no AgNP). Although, only five different genera of EMF were found on roots of the control plants, only one genus Laccaria was found on roots of plants grown in soil containing 350 mg AgNP/kg. At the higher levels of AgNP contamination, no EMF were observed. Furthermore, extractable silver was found in soils containing AgNP, indicating potential dissolution of silver ions (Ag+) from the solid AgNP.

  6. Soil contamination with silver nanoparticles reduces Bishop pine growth and ectomycorrhizal diversity on pine roots

    International Nuclear Information System (INIS)

    Soil contamination by silver nanoparticles (AgNP) is of potential environmental concern but little work has been carried out on the effect of such contamination on ectomycorrhizal fungi (EMF). EMF are essential to forest ecosystem functions as they are known to enhance growth of trees by nutrient transfer. In this study, soil was experimentally contaminated with AgNP (0, 350 and 790 mg Ag/kg) and planted with Bishop pine seedlings. The effect of AgNP was subsequently measured, assessing variation in pine growth and ectomycorrhizal diversity associated with the root system. After only 1 month, the highest AgNP level had significantly reduced the root length of pine seedlings, which in turn had a small effect on above ground plant biomass. However, after 4 months growth, both AgNP levels utilised had significantly reduced both pine root and shoot biomass. For example, even the lower levels of AgNP (350 mg Ag/kg) soil, reduced fresh root biomass by approximately 57 %. The root systems of the plants grown in AgNP-contaminated soils lacked the lateral and fine root development seen in the control plants (no AgNP). Although, only five different genera of EMF were found on roots of the control plants, only one genus Laccaria was found on roots of plants grown in soil containing 350 mg AgNP/kg. At the higher levels of AgNP contamination, no EMF were observed. Furthermore, extractable silver was found in soils containing AgNP, indicating potential dissolution of silver ions (Ag+) from the solid AgNP

  7. Square Root Relationship in Growth Kinetics of Silicate-1 Membranes

    Czech Academy of Sciences Publication Activity Database

    Novák, Pavel; Brabec, Libor; Šolcová, Olga; Bortnovsky, Oleg; Zikánová, Arlette; Kočiřík, Milan

    Amsterdam : Elsevier, 2002, s. 1505-1511. - (Studies in Surface Science and Catalysis.. 142 B). [International FEZA Conference /2./. Taormina (IT), 01.09.2002-05.09.2002] R&D Projects: GA ČR GA203/99/0522 Institutional research plan: CEZ:AV0Z4040901 Keywords : silicate-1 layer * growth kinetics * sedimentation Subject RIV: CF - Physical ; Theoretical Chemistry

  8. Ethylene Antagonizes Salt-Induced Growth Retardation and Cell Death Process via Transcriptional Controlling of Ethylene-, BAG- and Senescence-Associated Genes in Arabidopsis

    Science.gov (United States)

    Pan, Ya-Jie; Liu, Ling; Lin, Ying-Chao; Zu, Yuan-Gang; Li, Lei-Peng; Tang, Zhong-Hua

    2016-01-01

    The existing question whether ethylene is involved in the modulation of salt-induced cell death to mediate plant salt tolerance is important for understanding the salt tolerance mechanisms. Here, we employed Arabidopsis plants to study the possible role of ethylene in salt-induced growth inhibition and programmed cell death (PCD) profiles. The root length, DNA ladder and cell death indicated by Evan's blue detection were measured by compared to the control or salt-stressed seedlings. Secondly, the protoplasts isolated from plant leaves and dyed with Annexin V-FITC were subjected to flow cytometric (FCM) assay. Our results showed that ethylene works effectively in seedling protoplasts, antagonizing salt-included root retardation and restraining cell death both in seedlings or protoplasts. Due to salinity, the entire or partial insensitivity of ethylene signaling resulted in an elevated levels of cell death in ein2-5 and ein3-1 plants and the event were amended in ctr1-1 plants after salt treatment. The subsequent experiment with exogenous ACC further corroborated that ethylene could modulate salt-induced PCD process actively. Plant Bcl-2-associated athanogene (BAG) family genes are recently identified to play an extensive role in plant PCD processes ranging from growth, development to stress responses and even cell death. Our result showed that salinity alone significantly suppressed the transcripts of BAG6, BAG7 and addition of ACC in the saline solution could obviously re-activate BAG6 and BAG7 expressions, which might play a key role to inhibit the salt-induced cell death. In summary, our research implies that ethylene and salinity antagonistically control BAG family-, ethylene-, and senescence-related genes to alleviate the salt-induced cell death.

  9. Ethylene Antagonizes Salt-Induced Growth Retardation and Cell Death Process via Transcriptional Controlling of Ethylene-, BAG- and Senescence-Associated Genes in Arabidopsis.

    Science.gov (United States)

    Pan, Ya-Jie; Liu, Ling; Lin, Ying-Chao; Zu, Yuan-Gang; Li, Lei-Peng; Tang, Zhong-Hua

    2016-01-01

    The existing question whether ethylene is involved in the modulation of salt-induced cell death to mediate plant salt tolerance is important for understanding the salt tolerance mechanisms. Here, we employed Arabidopsis plants to study the possible role of ethylene in salt-induced growth inhibition and programmed cell death (PCD) profiles. The root length, DNA ladder and cell death indicated by Evan's blue detection were measured by compared to the control or salt-stressed seedlings. Secondly, the protoplasts isolated from plant leaves and dyed with Annexin V-FITC were subjected to flow cytometric (FCM) assay. Our results showed that ethylene works effectively in seedling protoplasts, antagonizing salt-included root retardation and restraining cell death both in seedlings or protoplasts. Due to salinity, the entire or partial insensitivity of ethylene signaling resulted in an elevated levels of cell death in ein2-5 and ein3-1 plants and the event were amended in ctr1-1 plants after salt treatment. The subsequent experiment with exogenous ACC further corroborated that ethylene could modulate salt-induced PCD process actively. Plant Bcl-2-associated athanogene (BAG) family genes are recently identified to play an extensive role in plant PCD processes ranging from growth, development to stress responses and even cell death. Our result showed that salinity alone significantly suppressed the transcripts of BAG6, BAG7 and addition of ACC in the saline solution could obviously re-activate BAG6 and BAG7 expressions, which might play a key role to inhibit the salt-induced cell death. In summary, our research implies that ethylene and salinity antagonistically control BAG family-, ethylene-, and senescence-related genes to alleviate the salt-induced cell death. PMID:27242886

  10. Specific effects of certain salts on the growth of roots of young corn seedlings

    OpenAIRE

    Mohammed Hatata; Michel Farah

    2014-01-01

    The effect of different concentrations of NaCl, Na2SO4, MgCl2 and MgSO4 on the growth in length of the first seminal root of corn, and on the change in dry weight of the whole seedling and its separate parts have been studied. The effect of mannitol was also investigated for comparison and to study the osmotic effect. The effect of salts on root growth was dependent on the salt species; all effects were specific for the ions investigated, not due to osmotic activity of the solution. The growt...

  11. Growth response of Casuarina equisetifolia Forst. rooted stem cuttings to Frankia in nursery and field conditions

    Indian Academy of Sciences (India)

    A Karthikeyan; K Chandrasekaran; M Geetha; R Kalaiselvi

    2013-11-01

    Casuarina equisetifolia Forst. is a tree crop that provides fuel wood, land reclamation, dune stabilization, and scaffolding for construction, shelter belts, and pulp and paper production. C. equisetifolia fixes atmospheric nitrogen through a symbiotic relationship with Frankia, a soil bacterium of the actinobacteria group. The roots of C. equisetifolia produce root nodules where the bacteria fix atmospheric nitrogen, which is an essential nutrient for all plant metabolic activities. However, rooted stem cuttings of elite clones of C. equisetifolia by vegetative propagation is being planted by the farmers of Pondicherry as costeffective method. As the vegetative propagation method uses inert material (vermiculite) for rooting there is no chance for Frankia association. Therefore after planting of these stocks the farmers are applying 150 kg of di-ammonium phosphate (DAP)/acre/year. To overcome this fertilizer usage, the Frankia-inoculated rooted stem cuttings were propagated under nursery conditions and transplanted in the nutrient-deficient soils of Karaikal, Pondicherry (India), in this study. Under nursery experiments the growth and biomass of C. equisetifolia rooted stem cuttings inoculated with Frankia showed 3 times higher growth and biomass than uninoculated control. These stocks were transplanted and monitored for their growth and survival for 1 year in the nutrient-deficient farm land. The results showed that the rooted stem cuttings of C. equisetifolia significantly improved growth in height (8.8 m), stem girth (9.6 cm) and tissue nitrogen content (3.3 mg g−1) than uninoculated controls. The soil nutrient status was also improved due to inoculation of Frankia.

  12. The Pseudomonas fluorescens Siderophore Pyoverdine Weakens Arabidopsis thaliana Defense in Favor of Growth in Iron-Deficient Conditions.

    Science.gov (United States)

    Trapet, Pauline; Avoscan, Laure; Klinguer, Agnès; Pateyron, Stéphanie; Citerne, Sylvie; Chervin, Christian; Mazurier, Sylvie; Lemanceau, Philippe; Wendehenne, David; Besson-Bard, Angélique

    2016-05-01

    Pyoverdines are siderophores synthesized by fluorescent Pseudomonas spp. Under iron-limiting conditions, these high-affinity ferric iron chelators are excreted by bacteria in the soil to acquire iron. Pyoverdines produced by beneficial Pseudomonas spp. ameliorate plant growth. Here, we investigate the physiological incidence and mode of action of pyoverdine from Pseudomonas fluorescens C7R12 on Arabidopsis (Arabidopsis thaliana) plants grown under iron-sufficient or iron-deficient conditions. Pyoverdine was provided to the medium in its iron-free structure (apo-pyoverdine), thus mimicking a situation in which it is produced by bacteria. Remarkably, apo-pyoverdine abolished the iron-deficiency phenotype and restored the growth of plants maintained in the iron-deprived medium. In contrast to a P. fluorescens C7R12 strain impaired in apo-pyoverdine production, the wild-type C7R12 reduced the accumulation of anthocyanins in plants grown in iron-deficient conditions. Under this condition, apo-pyoverdine modulated the expression of around 2,000 genes. Notably, apo-pyoverdine positively regulated the expression of genes related to development and iron acquisition/redistribution while it repressed the expression of defense-related genes. Accordingly, the growth-promoting effect of apo-pyoverdine in plants grown under iron-deficient conditions was impaired in iron-regulated transporter1 and ferric chelate reductase2 knockout mutants and was prioritized over immunity, as highlighted by an increased susceptibility to Botrytis cinerea This process was accompanied by an overexpression of the transcription factor HBI1, a key node for the cross talk between growth and immunity. This study reveals an unprecedented mode of action of pyoverdine in Arabidopsis and demonstrates that its incidence on physiological traits depends on the plant iron status. PMID:26956666

  13. Root-Specific Reduction of Cytokinin Causes Enhanced Root Growth, Drought Tolerance, and Leaf Mineral Enrichment in Arabidopsis and Tobacco

    Czech Academy of Sciences Publication Activity Database

    Werner, T.; Nehnevajova, E.; Koellmer, I.; Novák, Ondřej; Strnad, Miroslav; Kraemer, U.; Schmülling, T.

    2010-01-01

    Roč. 22, č. 12 (2010), s. 3905-3920. ISSN 1040-4651 Institutional research plan: CEZ:AV0Z50380511 Keywords : ENVIRONMENTAL RESPONSE PATHWAYS * PLANT PRODUCTIVITY * GRAIN-YIELD Subject RIV: EF - Botanics Impact factor: 9.396, year: 2010

  14. Effect of planting density on root lodging resistance and its relationship to nodal root growth characteristics in maize (Zea mays L.)

    DEFF Research Database (Denmark)

    Liu, Shengqun; Song, Fengbin; Liu, Fulai;

    2012-01-01

    Increase of planting density has been widely used to increase grain yield in maize. However, it may lead to higher risk of root lodging hence causing significant yield loss of the crop. The objective of this study was to investigate the effect of planting density on maize nodal root growth...

  15. Hypocotyl adventitious root organogenesis differs from lateral root development

    Directory of Open Access Journals (Sweden)

    Inge eVerstraeten

    2014-09-01

    Full Text Available Wound-induced adventitious root (AR formation is a requirement for plant survival upon root damage inflicted by pathogen attack, but also during the regeneration of plant stem cuttings for clonal propagation of elite plant varieties. Yet, adventitious rooting also takes place without wounding. This happens for example in etiolated Arabidopsis thaliana hypocotyls, in which AR initiate upon de-etiolation or in tomato seedlings, in which AR initiate upon flooding or high water availability. In the hypocotyl AR originate from a cell layer reminiscent to the pericycle in the primary root (PR and the initiated AR share histological and developmental characteristics with lateral roots (LR. In contrast to the PR however, the hypocotyl is a determinate structure with an established final number of cells. This points to differences between the induction of hypocotyl AR and LR on the PR, as the latter grows indeterminately. The induction of AR on the hypocotyl takes place in environmental conditions that differ from those that control LR formation. Hence, AR formation depends on differentially regulated gene products. Similarly to AR induction in stem cuttings, the capacity to induce hypocotyl AR is genotype-dependent and the plant growth regulator auxin is a key regulator controlling the rooting response. The hormones cytokinins, ethylene, jasmonic acid and strigolactones in general reduce the root-inducing capacity. The involvement of this many regulators indicates that a tight control and fine-tuning of the initiation and emergence of AR exists. Recently, several genetic factors, specific to hypocotyl adventitious rooting in Arabidopsis thaliana, have been uncovered. These factors reveal a dedicated signaling network that drives AR formation in the Arabidopsis hypocotyl. Here we provide an overview of the environmental and genetic factors controlling hypocotyl-born AR and we summarize how AR formation and the regulating factors of this organogenesis are

  16. The cytokinin response factors modulate root and shoot growth and promote leaf senescence in Arabidopsis

    Czech Academy of Sciences Publication Activity Database

    Raines, T.; Shanks, C.; Cheng, C.Y.; McPherson, D.; Argueso, C.T.; Kim, H.J.; Franco-Zorrilla, J.M.; Lopez-Vidriero, I.; Solano, R.; Vaňková, Radomíra; Schaller, G.E.; Kieber, J.J.

    2016-01-01

    Roč. 85, č. 1 (2016), s. 134-147. ISSN 0960-7412 Institutional support: RVO:61389030 Keywords : cytokinin * two-component signaling * transcription factors Subject RIV: EF - Botanics Impact factor: 5.972, year: 2014

  17. Root growth of Lotus corniculatus interacts with P distribution in young sandy soil

    Directory of Open Access Journals (Sweden)

    R. Schulin

    2012-07-01

    Full Text Available Large areas of land are restored with un-weathered soil substrates following mining activities in eastern Germany and elsewhere. In the initial stages of colonization of such land by vegetation, plant roots may become key agents in generating soil formation patterns by introducing gradients in chemical and physical soil properties. On the other hand, such patterns may be influenced by root growth responses to pre-existing substrate heterogeneities. In particular, the roots of many plants were found to preferentially proliferate into nutrient-rich patches. Phosphorus (P is of primary interest in this respect because its availability is often low in unweathered soils, limiting especially the growth of leguminous plants. However, leguminous plants occur frequently among the pioneer plant species on such soils as they only depend on atmospheric nitrogen (N fixation as N source. In this study we investigated the relationship between root growth allocation of the legume Lotus corniculatus and soil P distribution on recently restored land. As test sites the experimental Chicken Creek Catchment (CCC in eastern Germany and a nearby experimental site (ES with the same soil substrate were used. We established two experiments with constructed heterogeneity, one in the field on the experimental site and the other in a climate chamber. In addition we conducted high-density samplings on undisturbed soil plots colonized by L. corniculatus on the ES and on the CCC. In the field experiment, we installed cylindrical ingrowth soil cores (4.5×10 cm with and without P fertilization around single two-month-old L. corniculatus plants. Roots showed preferential growth into the P-fertilized ingrowth-cores. Preferential root allocation was also found in the climate chamber experiment, where single L. corniculatus plants were grown in containers filled with ES soil and where a lateral portion of the containers was additionally supplied with a range of different P

  18. Root growth of Lotus corniculatus interacts with P distribution in young sandy soil

    Directory of Open Access Journals (Sweden)

    B. Felderer

    2013-03-01

    Full Text Available Large areas of land are restored with unweathered soil substrates following mining activities in eastern Germany and elsewhere. In the initial stages of colonization of such land by vegetation, plant roots may become key agents in generating soil formation patterns by introducing gradients in chemical and physical soil properties. On the other hand, such patterns may be influenced by root growth responses to pre-existing substrate heterogeneities. In particular, the roots of many plants were found to preferentially proliferate into nutrient-rich patches. Phosphorus (P is of primary interest in this respect because its availability is often low in unweathered soils, limiting especially the growth of leguminous plants. However, leguminous plants occur frequently among the pioneer plant species on such soils, as they only depend on atmospheric nitrogen (N fixation as N source. In this study we investigated the relationship between root growth allocation of the legume Lotus corniculatus and soil P distribution on recently restored land. As test sites, the experimental Chicken Creek Catchment (CCC in eastern Germany and a nearby experimental site (ES with the same soil substrate were used. We established two experiments with constructed heterogeneity, one in the field on the experimental site and the other in a climate chamber. In addition, we conducted high-density samplings on undisturbed soil plots colonized by L. corniculatus on the ES and on the CCC. In the field experiment, we installed cylindrical ingrowth soil cores (4.5 × 10 cm with and without P fertilization around single two-month-old L. corniculatus plants. Roots showed preferential growth into the P-fertilized ingrowth-cores. Preferential root allocation was also found in the climate chamber experiment, where single L. corniculatus plants were grown in containers filled with ES soil and where a lateral portion of the containers was additionally supplied with a range of different P

  19. The effect of ethylene on root growth of Zea mays seedlings

    Science.gov (United States)

    Whalen, M. C.; Feldman, L. J.

    1988-01-01

    The control of primary root growth in Zea mays cv. Merit by ethylene was examined. At applied concentrations of ethylene equal to or greater than 0.1 microliter L-1, root elongation during 24 h was inhibited. The half-maximal response occurred at 0.6 microliter L-1 and the response saturated at 6 microliters L-1. Inhibition of elongation took place within 20 min. However, after ethylene was removed, elongation recovered to control values within 15 min. Root elongation was also inhibited by green light. The inhibition caused by a 24-h exposure to ethylene was restricted to the elongating region just behind the apex, with inhibition of cortical cell elongation being the primary contributor to the effect. Based on use of 2,5-norbornadiene, a gaseous competitive inhibitor of ethylene, it was concluded that endogenous ethylene normally inhibits root elongation.

  20. Phosphate-dependent root system architecture responses to salt stress

    KAUST Repository

    Kawa, Dorota

    2016-05-20

    Nutrient availability and salinity of the soil affect growth and development of plant roots. Here, we describe how phosphate availability affects root system architecture (RSA) of Arabidopsis and how phosphate levels modulate responses of the root to salt stress. Phosphate (Pi) starvation reduced main root length and increased the number of lateral roots of Arabidopsis Col-0 seedlings. In combination with salt, low Pi dampened the inhibiting effect of mild salt stress (75mM) on all measured RSA components. At higher NaCl concentrations, the Pi deprivation response prevailed over the salt stress only for lateral root elongation. The Pi deprivation response of lateral roots appeared to be oppositely affected by abscisic acid (ABA) signaling compared to the salt stress response. Natural variation in the response to the combination treatment of salt and Pi starvation within 330 Arabidopsis accessions could be grouped into four response patterns. When exposed to double stress, in general lateral roots prioritized responses to salt, while the effect on main root traits was additive. Interestingly, these patterns were not identical for all accessions studied and multiple strategies to integrate the signals from Pi deprivation and salinity were identified. By Genome Wide Association Mapping (GWAS) 13 genomic loci were identified as putative factors integrating responses to salt stress and Pi starvation. From our experiments, we conclude that Pi starvation interferes with salt responses mainly at the level of lateral roots and that large natural variation exists in the available genetic repertoire of accessions to handle the combination of stresses.

  1. Growth bioregulatory role of root-applied thiourea: changes in growth, toxicity symptoms and photosynthetic pigments of maize

    International Nuclear Information System (INIS)

    While seed or foliar application of thiourea (TU) has the potential to modulate plant growth, studies reporting such bioregulatory role(s) of root-applied TU are limited. Here we report the growth regulation by root-applied TU in nine maize (Zea mays L.) varieties grown using sand culture. Thirty day old plants were treated with 0 - 1.25 mM TU levels dissolved in nutrient solution, and the data recorded 20 days later. The parameters studied were symptoms of TU toxicity, growth and photosynthetic pigment contents. Results revealed that 0.25 mM TU promoted the growth of all varieties; 0.50 mM did so in some, while 0.75 - 1.25 mM TU was inhibitory to all varieties. Higher TU levels (1.00 - 1.25 mM) produced more intensive toxicity symptoms such as yellowing of leaves, and browning and constriction of roots but with significant varietal differences; Pak-Afgoi showed the lowest while EV-20 had the highest incidence of symptoms. Lowest TU level (0.25 mM) increased the photosynthetic pigments in all the varieties, while higher levels (1.00 1.25) reduced chlorophyll (Chl) b and carotenoids (Car) contents and increased Chl:Car ratio more legibly in the sensitive varieties. There were no correlations of toxicity symptoms with growth and leaf pigments contents at 0.25 mM TU but these correlations were negative for shoot weight, number and area of leaves and Chl b, Car and Chl:Car ratio of leaves at 1.25 mM (toxic) level of TU. Likewise, root dry weight of maize varieties was negatively correlated with root constriction and root browning. Results suggest that higher levels of TU had pronounced influence on the root functions leading to reduced dry weight. From the current results we believe that TU has a definitive growth bioregulatory activity as it improved photosynthetic pigments contents at lower level (0.25 mM) but deteriorated them at higher levels (0.75 - 1.25 mM). Substantial varietal differences suggested that TU effects are genetically-related in maize. Possible

  2. AtMSL9 and AtMSL10: Sensors of plasma membrane tension in Arabidopsis roots

    OpenAIRE

    Peyronnet, Rémi; Haswell, Elizabeth S.; Barbier-Brygoo, Hélène; Frachisse, Jean-Marie

    2008-01-01

    Plant cells, like those of animals and bacteria, are able to sense physical deformation of the plasma membrane. Mechanosensitive (MS) channels are proteins that transduce mechanical force into ion flux, providing a mechanism for the perception of mechanical stimuli such as sound, touch and osmotic pressure. We recently identified AtMSL9 and AtMSL10, two mechanosensitive channels in Arabidopsis thaliana, as molecular candidates for mechanosensing in higher plants.1 AtMSL9 and AtMSL10 are membe...

  3. Turgor Regulation in Osmotically Stressed Arabidopsis Epidermal Root Cells. Direct Support for the Role of Inorganic Ion Uptake as Revealed by Concurrent Flux and Cell Turgor Measurements1

    Science.gov (United States)

    Shabala, Sergey N.; Lew, Roger R.

    2002-01-01

    Hyperosmotic stress is known to significantly enhance net uptake of inorganic ions into plant cells. Direct evidence for cell turgor recovery via such a mechanism, however, is still lacking. In the present study, we performed concurrent measurements of net ion fluxes (with the noninvasive microelectrode ion flux estimation technique) and cell turgor changes (with the pressure-probe technique) to provide direct evidence that inorganic ion uptake regulates turgor in osmotically stressed Arabidopsis epidermal root cells. Immediately after onset of hyperosmotic stress (100/100 mm mannitol/sorbitol treatment), the cell turgor dropped from 0.65 to about 0.25 MPa. Turgor recovery started within 2 to 10 min after the treatment and was accompanied by a significant (30–80 nmol m−2 s−1) increase in uptake of K+, Cl−, and Na+ by root cells. In most cells, almost complete (>90% of initial values) recovery of the cell turgor was observed within 40 to 50 min after stress onset. In another set of experiments, we combined the voltage-clamp and the microelectrode ion flux estimation techniques to show that this process is, in part, mediated by voltage-gated K+ transporters at the cell plasma membrane. The possible physiological significance of these findings is discussed. PMID:12011359

  4. Effects of the plant growth-promoting bacterium Burkholderia phytofirmans PsJN throughout the life cycle of Arabidopsis thaliana.

    Directory of Open Access Journals (Sweden)

    María Josefina Poupin

    Full Text Available Plant growth-promoting rhizobacteria (PGPR induce positive effects in plants, such as increased growth or reduced stress susceptibility. The mechanisms behind PGPR/plant interaction are poorly understood, as most studies have described short-term responses on plants and only a few studies have analyzed plant molecular responses under PGPR colonization. Here, we studied the effects of the PGPR bacterial model Burkholderiaphytofirmans PsJN on the whole life cycle of Arabidopsis thaliana plants. We reported that at different plant developmental points, strain PsJN can be found in the rhizosphere and also colonizing their internal tissues. In early ontogeny, strain PsJN increased several growth parameters and accelerated growth rate of the plants. Also, an Arabidopsis transcriptome analysis revealed that 408 genes showed differential expression in PsJN-inoculated plants; some of these genes are involved in stress response and hormone pathways. Specifically, genes implicated in auxin and gibberellin pathways were induced. Quantitative transcriptional analyses of selected genes in different developmental stages revealed that the beginning of these changes could be evidenced early in development, especially among the down-regulated genes. The inoculation with heat-killed bacteria provoked a more severe transcriptional response in plants, but was not able to induce plant growth-promotion. Later in ontogeny, the growth rates of inoculated plants decreased with respect to the non-inoculated group and, interestingly, the inoculation accelerated the flowering time and the appearance of senescence signs in plants; these modifications correlate with the early up-regulation of flowering control genes. Then, we show that a single inoculation with a PGPR could affect the whole life cycle of a plant, accelerating its growth rate and shortening its vegetative period, both effects relevant for most crops. Thus, these findings provide novel and interesting aspects

  5. Auxin transport is sufficient to generate a maximumand gradient guiding root growth

    NARCIS (Netherlands)

    Grieneisen, V.; Xu, J.; Marée, A.F.M.; Hogeweg, P.; Scheres, B.J.G.

    2007-01-01

    The plant growth regulator auxin controls cell identity, cell division and cell expansion. Auxin efflux facilitators (PINs) are associated with auxin maxima in distal regions of both shoots and roots. Here we model diffusion and PIN-facilitated auxin transport in and across cells within a structured

  6. The Effects of Different Amounts of Controlled Release Fertilizer on the Root Growth and the Filling Rate in Winter Wheat

    OpenAIRE

    Meng Li; Jingtian Yang; Liyuan Yan; Yan Shi

    2014-01-01

    In order to increase the fertilizer use efficiency and yield in winter wheat, the effects of controlled release fertilizer on the root growth and the filling rate in winter wheat by applying different amounts of controlled release fertilizer had been studied in open field. The results indicated that conventional complex fertilizer and controlled release fertilizer could cause corresponding changes of the wheat root activity, dry root weight, root-shoot ratio and filling rate, but the fertiliz...

  7. The thanatos mutation in Arabidopsis thaliana cellulose synthase 3 (AtCesA3) has a dominant-negative effect on cellulose synthesis and plant growth.

    Science.gov (United States)

    Daras, Gerasimos; Rigas, Stamatis; Penning, Bryan; Milioni, Dimitra; McCann, Maureen C; Carpita, Nicholas C; Fasseas, Constantinos; Hatzopoulos, Polydefkis

    2009-01-01

    Genetic functional analyses of mutants in plant genes encoding cellulose synthases (CesAs) have suggested that cellulose deposition requires the activity of multiple CesA proteins. Here, a genetic screen has led to the identification of thanatos (than), a semi-dominant mutant of Arabidopsis thaliana with impaired growth of seedlings. Homozygous seedlings of than germinate and grow but do not survive. In contrast to other CesA mutants, heterozygous plants are dwarfed and display a radially swollen root phenotype. Cellulose content is reduced by approximately one-fifth in heterozygous and by two-fifths in homozygous plants, showing gene-dosage dependence. Map-based cloning revealed an amino acid substitution (P578S) in the catalytic domain of the AtCesA3 gene, indicating a critical role for this residue in the structure and function of the cellulose synthase complex. Ab initio analysis of the AtCesA3 subdomain flanking the conserved proline residue predicted that the amino acid substitution to serine alters protein secondary structure in the catalytic domain. Gene dosage-dependent expression of the AtCesA3 mutant gene in wild-type A. thaliana plants resulted in a than dominant-negative phenotype. We propose that the incorporation of a mis-folded CesA3 subunit into the cellulose synthase complex may stall or prevent the formation of functional rosette complexes. PMID:19645738

  8. Assessment of chromium efficacy on germination, root elongation, and coleoptile growth of wheat (Triticum aestivum L.) at different growth periods.

    Science.gov (United States)

    Dotaniya, M L; Das, H; Meena, V D

    2014-05-01

    The tannery effluents contain a high concentration of chromium (Cr). It drastically reduces the crop yield when used for irrigation purpose. A huge volume of tannery effluents is available as irrigation for crop production. It is negatively affecting germination as well as yield of the crop. The wheat seeds were exposed to five different concentrations of Cr (0, 20, 40, 80, and 100 ppm). In Petri plates, 100 seeds were placed and the germination percent was recorded after 72 hour (h). Root elongation and coleoptile growth were measured at 72, 120, 168, and 240 h. Results showed that the germination percent of the test crop decreased with increasing Cr levels. It decreased by 6, 14, 30, and 37 % under the Cr concentration of 20, 40, 80, and 100 ppm, respectively. The root elongation was more sensitive than the coleoptile growth. The negative correlation was found between Cr levels and root elongation as well as coleoptile growth. These growth parameters were significantly affected up to 80 ppm of Cr level. The wheat growers using tannery effluent as irrigation should be well treated prior to application. PMID:24415062

  9. IAA-Ala Resistant3, an evolutionarily conserved target of miR167, mediates Arabidopsis root architecture changes during high osmotic stress

    KAUST Repository

    Kinoshita, Natsuko

    2012-09-01

    The functions of microRNAs and their target mRNAs in Arabidopsis thaliana development have been widely documented; however, roles of stress-responsive microRNAs and their targets are not as well understood. Using small RNA deep sequencing and ATH1 microarrays to profile mRNAs, we identified IAA-Ala Resistant3 (IAR3) as a new target of miR167a. As expected, IAR3 mRNA was cleaved at the miR167a complementary site and under high osmotic stress miR167a levels decreased, whereas IAR3 mRNA levels increased. IAR3 hydrolyzes an inactive form of auxin (indole-3-acetic acid [IAA]-alanine) and releases bioactive auxin (IAA), a central phytohormone for root development. In contrast with the wild type, iar3 mutants accumulated reduced IAA levels and did not display high osmotic stress-induced root architecture changes. Transgenic plants expressing a cleavage-resistant form of IAR3 mRNA accumulated high levels of IAR3 mRNAs and showed increased lateral root development compared with transgenic plants expressing wild-type IAR3. Expression of an inducible noncoding RNA to sequester miR167a by target mimicry led to an increase in IAR3 mRNA levels, further confirming the inverse relationship between the two partners. Sequence comparison revealed the miR167 target site on IAR3 mRNA is conserved in evolutionarily distant plant species. Finally, we showed that IAR3 is required for drought tolerance. © 2012 American Society of Plant Biologists. All rights reserved.

  10. Phenotyping pipeline reveals major seedling root growth QTL in hexaploid wheat.

    Science.gov (United States)

    Atkinson, Jonathan A; Wingen, Luzie U; Griffiths, Marcus; Pound, Michael P; Gaju, Oorbessy; Foulkes, M John; Le Gouis, Jacques; Griffiths, Simon; Bennett, Malcolm J; King, Julie; Wells, Darren M

    2015-04-01

    Seedling root traits of wheat (Triticum aestivum L.) have been shown to be important for efficient establishment and linked to mature plant traits such as height and yield. A root phenotyping pipeline, consisting of a germination paper-based screen combined with image segmentation and analysis software, was developed and used to characterize seedling traits in 94 doubled haploid progeny derived from a cross between the winter wheat cultivars Rialto and Savannah. Field experiments were conducted to measure mature plant height, grain yield, and nitrogen (N) uptake in three sites over 2 years. In total, 29 quantitative trait loci (QTLs) for seedling root traits were identified. Two QTLs for grain yield and N uptake co-localize with root QTLs on chromosomes 2B and 7D, respectively. Of the 29 root QTLs identified, 11 were found to co-localize on 6D, with four of these achieving highly significant logarithm of odds scores (>20). These results suggest the presence of a major-effect gene regulating seedling root vigour/growth on chromosome 6D. PMID:25740921

  11. A novel bHLH transcription factor PebHLH35 from Populus euphratica confers drought tolerance through regulating stomatal development, photosynthesis and growth in Arabidopsis

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Yan [College of Biological Sciences and Technology, National Engineering Laboratory for Tree Breeding, Beijing Forestry University, Beijing 100083 (China); Liaoning Forestry Vocational-Technical College, Shenyang 110101 (China); Wang, Congpeng; Han, Xiao; Tang, Sha; Liu, Sha [College of Biological Sciences and Technology, National Engineering Laboratory for Tree Breeding, Beijing Forestry University, Beijing 100083 (China); Xia, Xinli, E-mail: xiaxl@bjfu.edu.cn [College of Biological Sciences and Technology, National Engineering Laboratory for Tree Breeding, Beijing Forestry University, Beijing 100083 (China); Yin, Weilun, E-mail: yinwl@bjfu.edu.cn [College of Biological Sciences and Technology, National Engineering Laboratory for Tree Breeding, Beijing Forestry University, Beijing 100083 (China)

    2014-07-18

    Highlights: • PebHLH35 is firstly cloned from Populus euphratica and characterized its functions. • PebHLH35 is important for earlier seedling establishment and vegetative growth. • PebHLH35 enhances tolerance to drought by regulating growth. • PebHLH35 enhances tolerance to drought by regulating stomatal development. • PebHLH35 enhances tolerance to drought by regulating photosynthesis and transpiration. - Abstract: Plant basic helix-loop-helix (bHLH) transcription factors (TFs) are involved in a variety of physiological processes including the regulation of plant responses to various abiotic stresses. However, few drought-responsive bHLH family members in Populus have been reported. In this study, a novel bHLH gene (PebHLH35) was cloned from Populus euphratica. Expression analysis in P. euphratica revealed that PebHLH35 was induced by drought and abscisic acid. Subcellular localization studies using a PebHLH35-GFP fusion showed that the protein was localized to the nucleus. Ectopic overexpression of PebHLH35 in Arabidopsis resulted in a longer primary root, more leaves, and a greater leaf area under well-watered conditions compared with vector control plants. Notably, PebHLH35 overexpression lines showed enhanced tolerance to water-deficit stress. This finding was supported by anatomical and physiological analyses, which revealed a reduced stomatal density, stomatal aperture, transpiration rate, and water loss, and a higher chlorophyll content and photosynthetic rate. Our results suggest that PebHLH35 functions as a positive regulator of drought stress responses by regulating stomatal density, stomatal aperture, photosynthesis and growth.

  12. A novel bHLH transcription factor PebHLH35 from Populus euphratica confers drought tolerance through regulating stomatal development, photosynthesis and growth in Arabidopsis

    International Nuclear Information System (INIS)

    Highlights: • PebHLH35 is firstly cloned from Populus euphratica and characterized its functions. • PebHLH35 is important for earlier seedling establishment and vegetative growth. • PebHLH35 enhances tolerance to drought by regulating growth. • PebHLH35 enhances tolerance to drought by regulating stomatal development. • PebHLH35 enhances tolerance to drought by regulating photosynthesis and transpiration. - Abstract: Plant basic helix-loop-helix (bHLH) transcription factors (TFs) are involved in a variety of physiological processes including the regulation of plant responses to various abiotic stresses. However, few drought-responsive bHLH family members in Populus have been reported. In this study, a novel bHLH gene (PebHLH35) was cloned from Populus euphratica. Expression analysis in P. euphratica revealed that PebHLH35 was induced by drought and abscisic acid. Subcellular localization studies using a PebHLH35-GFP fusion showed that the protein was localized to the nucleus. Ectopic overexpression of PebHLH35 in Arabidopsis resulted in a longer primary root, more leaves, and a greater leaf area under well-watered conditions compared with vector control plants. Notably, PebHLH35 overexpression lines showed enhanced tolerance to water-deficit stress. This finding was supported by anatomical and physiological analyses, which revealed a reduced stomatal density, stomatal aperture, transpiration rate, and water loss, and a higher chlorophyll content and photosynthetic rate. Our results suggest that PebHLH35 functions as a positive regulator of drought stress responses by regulating stomatal density, stomatal aperture, photosynthesis and growth

  13. Fe-Chlorophyllin Promotes the Growth of Wheat Roots Associated with Nitric Oxide Generation

    Directory of Open Access Journals (Sweden)

    Hui Jiang

    2010-12-01

    Full Text Available : Effects of Fe-chlorophyllin on the growth of wheat root were investigated in this study. We found that Fe-chlorophyllin can promote root growth. The production of nitric oxide in wheat root was detected using DAF-2DA fluorescent emission. The intensity of fluorescent in the presence of 0.1 mg/L Fe-chlorophyllin was near to that observed with the positive control of sodium nitroprusside (SNP, the nitric oxide donor. IAA oxidase activity decreased with all treatments of Fe-chlorophyllin from 0.01 to 10 mg/L. At the relatively lower Fe-chlorophyllin concentration of 0.1 mg/L, the activity of IAA oxidase displayed a remarkable decrease, being 40.1% lower than the control. Meanwhile, Fe-chlorophyllin treatment could increase the activities of reactive oxygen scavenging enzymes, such as superoxide dismutase (SOD and peroxidase (POD, as determined using non-denaturing polyacrylamide gel electrophoresis. These results indicate that Fe-chlorophyllin contributes to the growth of wheat root associated with nitric oxide generation.

  14. Effects of Growth Environment and Ulking Rate on Cyanogenic Potential of Cassava Tuerous Roots

    International Nuclear Information System (INIS)

    Various abiotic factors affect the pattern of growth and accumulation of cyanogenic glucosides in cassava plants. Five cassava genotypes were planted in a wet and a dry agro-ecological zone and analyzed at 4, 6, 8, 10 and 12 months after planting for tuberous root bulking rate and cyanogenic potential. Cassava plants at Ibadan (the wetter zone) had higher tuberous roots bulking rate and lower cynogenic potential than those planted at Minjibir (the drier zone). Root bulking rate at Ibadan increased from 4 to 6 months after planting, fell to 10 months, and then levelled off thereafter. At Majorana, bulking rate increased from 4 to 6 months, levelling off u pto 8 months after planting, and then falling slightly u pto to 10 months, and rising gradually u pto 12 months after planting. At Minijibir, the 6-8 months after planting period coincided with drought and the highest root bulking rate but increasing cyanogenic potential. Similarly, at Ibadan the 6-8 months after planting period coincided with drought and the highest root bulking rate but increasing cyanogenic potential. Despite the onset of drought, bulking continued up to 8 months after planting, falling u pto 10 months and levelling off thereafter at both agro-ecological zones. However, whereas cyanogenic potential rose rapidly after 8 months to peak at 10 months, and levelling off up to 12 months at Minjibir, cyanogenic potential levelled of after 8 u pto 12 months at Ibadan. Correlation and regression analysis suggested that root bulking rate and cyanogenic potential were negatively associated, meaning that an increase in root bulking rate would lead to corresponding decrease in it's cyanogenic potential which is highly desirable. This study has demonstrated that whereas the plant age and genotypic effects are not important factors in determining tuberous roots bulking rate and cyanogenic potential of cassava, the agro-ecological zone effect is an important factor in determining them

  15. Contribution of Root Proliferation in Nutrient-Rich Soil Patches to Nutrient Uptake and Growth of Maize

    Institute of Scientific and Technical Information of China (English)

    LI Hong-Bo; ZHANG Fu-Suo; SHEN Jian-Bo

    2012-01-01

    Root proliferation can be stimulated in a heterogeneous nutrient patch; however,the functions of the root proliferation in the nutrient-rich soil patches are not fully understood.In the present study,a two-year field experiment was conducted to examine the comparative effects of localized application of ammonium and phosphorus (P) at early or late stages on root growth,nutrient uptake,and biomass of maize (Zea mays L.) on a calcareous soil in an intensive farming system.Localized supply of ammonium and P had a more evident effect on shoot and root growth,and especially stimulated fine root development at the early seedling stage,with most of the maize roots being allocated to the nutrient-rich patch in the topsoil.Although localized ammonium and P supply at the late stage also enhanced the fine root growth,the plant roots in the patch accounted for a low proportion of the whole maize roots in the topsoil at the flowering stage.Compared with the early stage,fine root length in the short-lived nutrient patch decreased by 44%-62% and the shoot dry weight was not different between heterogeneous and homogeneous nutrient supply at the late growth stage.Localized supply of ammonium and P significantly increased N and P accumulation by maize at 35 and 47 days after sowing (DAS); however,no significant difference was found among the treatments at 82 DAS and the later growth stages.The increased nutrient uptake and plant growth was related to the higher proportion of root length in the localized nutrient-enriched patch.The results indicated that root proliferation in nutrient patches contributed more to maize growth and nutrient uptake at the early than late stages.

  16. Mobile phone radiation inhibits Vigna radiata (mung bean) root growth by inducing oxidative stress

    International Nuclear Information System (INIS)

    During the last couple of decades, there has been a tremendous increase in the use of cell phones. It has significantly added to the rapidly increasing EMF smog, an unprecedented type of pollution consisting of radiation in the environment, thereby prompting the scientists to study the effects on humans. However, not many studies have been conducted to explore the effects of cell phone EMFr on growth and biochemical changes in plants. We investigated whether EMFr from cell phones inhibit growth of Vigna radiata (mung bean) through induction of conventional stress responses. Effects of cell phone EMFr (power density: 8.55 μW cm-2; 900 MHz band width; for 1/2, 1, 2, and 4 h) were determined by measuring the generation of reactive oxygen species (ROS) in terms of malondialdehyde and hydrogen peroxide (H2O2) content, root oxidizability and changes in levels of antioxidant enzymes. Our results showed that cell phone EMFr significantly inhibited the germination (at ≥2 h), and radicle and plumule growths (≥1 h) in mung bean in a time-dependent manner. Further, cell phone EMFr enhanced MDA content (indicating lipid peroxidation), and increased H2O2 accumulation and root oxidizability in mung bean roots, thereby inducing oxidative stress and cellular damage. In response to EMFr, there was a significant upregulation in the activities of scavenging enzymes, such as superoxide dismutases, ascorbate peroxidases, guaiacol peroxidases, catalases and glutathione reductases, in mung bean roots. The study concluded that cell phone EMFr inhibit root growth of mung bean by inducing ROS-generated oxidative stress despite increased activities of antioxidant enzymes.

  17. The Arabidopsis thylakoid transporter PHT4;1 influences phosphate availability for ATP synthesis and plant growth.

    Science.gov (United States)

    Karlsson, Patrik M; Herdean, Andrei; Adolfsson, Lisa; Beebo, Azeez; Nziengui, Hugues; Irigoyen, Sonia; Ünnep, Renáta; Zsiros, Ottó; Nagy, Gergely; Garab, Győző; Aronsson, Henrik; Versaw, Wayne K; Spetea, Cornelia

    2015-10-01

    The Arabidopsis phosphate transporter PHT4;1 was previously localized to the chloroplast thylakoid membrane. Here we investigated the physiological consequences of the absence of PHT4;1 for photosynthesis and plant growth. In standard growth conditions, two independent Arabidopsis knockout mutant lines displayed significantly reduced leaf size and biomass but normal phosphorus content. When mutants were grown in high-phosphate conditions, the leaf phosphorus levels increased and the growth phenotype was suppressed. Photosynthetic measurements indicated that in the absence of PHT4;1 stromal phosphate was reduced to levels that limited ATP synthase activity. This resulted in reduced CO2 fixation and accumulation of soluble sugars, limiting plant growth. The mutants also displayed faster induction of non-photochemical quenching than the wild type, in line with the increased contribution of ΔpH to the proton-motive force across thylakoids. Small-angle neutron scattering showed a smaller lamellar repeat distance, whereas circular dichroism spectroscopy indicated a perturbed long-range order of photosystem II (PSII) complexes in the mutant thylakoids. The absence of PHT4;1 did not alter the PSII repair cycle, as indicated by wild-type levels of phosphorylation of PSII proteins, inactivation and D1 protein degradation. Interestingly, the expression of genes for several thylakoid proteins was downregulated in the mutants, but the relative levels of the corresponding proteins were either not affected or could not be discerned. Based on these data, we propose that PHT4;1 plays an important role in chloroplast phosphate compartmentation and ATP synthesis, which affect plant growth. It also maintains the ionic environment of thylakoids, which affects the macro-organization of complexes and induction of photoprotective mechanisms. PMID:26255788

  18. The Arabidopsis B-sister MADS-box protein, GORDITA, represses fruit growth and contributes to integument development.

    Science.gov (United States)

    Prasad, Kalika; Zhang, Xiuwen; Tobón, Emilio; Ambrose, Barbara A

    2010-04-01

    The MADS-box family of transcription factors have diverse developmental roles in flower pattern formation, gametophyte cell division and fruit differentiation. The B-sister MADS-box proteins are most similar to the B-class floral homeotic proteins, and are expressed in female reproductive organs. The Arabidopsis B-sister MADS-box protein, TT16, is necessary for inner integument differentiation. We have functionally characterized the only other B-sister MADS-box gene in Arabidopsis, AGL63, renamed here as GORDITA (GOA). A loss-of-function mutation in goa or reduction of endogenous GOA expression results in larger fruits, illustrating its novel function in regulating fruit growth. Consistent with its function, GOA expression is detected in the walls of the valves and throughout the replum of the fruit. Our phenotypic and molecular analyses of 35S::GOA and goa plants show that GOA controls organ size via cell expansion. Further, functional studies of goa tt16 double mutants have shown their additive role in controlling seed coat development, and have revealed the importance of GOA expression in the outer integument. Together, our studies provide evidence of a new regulatory role for a B-sister MADS-box gene in the control of organ growth. PMID:20088901

  19. Diurnal Dependence of Growth Responses to Shade in Arabidopsis: Role of Hormone, Clock,and Light Signaling

    Institute of Scientific and Technical Information of China (English)

    Romina Sellaro; Manuel Pacín; Jorge J. Casal

    2012-01-01

    We investigated the diurnal dependence of the hypocotyl-growth responses to shade under sunlight-night cycles in Arabidopsis thaliana.Afternoon shade events promoted hypocotyl growth,while morning shade was ineffective.The Ihy-D,elf3,lux,pif4 pif5,toc1,and quadruple della mutants retained the response to afternoon shade and the lack of response to morning shade while the Ihy cca 1 mutant responded to both morning and afternoon shade.The phyB mutant,plants overexpressing the multidrug resistance-like membrane protein ABCB19,and the iaa17/axr3 loss-of-function mutant failed to respond to shade.Transient exposure of sunlight-grown seedlings to synthetic auxin in the afternoon caused a stronger promotion of hypocotyl growth than morning treatments.The promotion of hypocotyl growth by afternoon shade or afternoon auxin required light perceived by phytochrome A or cryptochromes during the previous hours of the photoperiod.Although the ELF4-ELF3-LUX complex,PIF4,PIF5,and DELLA are key players in the generation of diurnal hypocotyl-growth patterns,they exert a minor role in the control of the diurnal pattern of growth responses to shade.We conclude that the strong diurnal dependency of hypocotyl-growth responses to shade relates to the balance between the antagonistic actions of LHY-CCA1 and a light-derived signal.

  20. Growth dynamics of fine roots in a coniferous fern forest site close to Forsmark in the central part of Sweden

    International Nuclear Information System (INIS)

    The seasonal growth dynamics of live and dead roots for trees and the field layer species (g/m2, varying diameter fractions) and live/dead ratios were analysed at a fresh/moist coniferous fern forest site close to the nuclear power plant at Forsmark in the central eastern parts of Sweden. The changes in depth distribution of fine roots were observed at depth intervals of the top humus horizon down to 40 cm in the mineral soil profile. The bulk of living fine roots of trees (2. The total quantity of fine roots (live + dead) amounted to 543, 434, 314 and 546 g/m2. Considerable quantities of fine roots (< 1 mm in diameter) were attributed to field-layer species (about 18% of the total biomass during the whole period of investigation). The turnover rate (the rate of construction of new roots) for tree fine roots < 1 mm in diameter amounted to at least the size of the average fine-root biomass. Our methods of estimating fine-root production and mortality, involved periodic measurements of live and dead dry weight of the fine roots from sequential core samples of the forest soil. The collected data give a proper and instant measure of the spatial and temporal distribution of fine roots in the undisturbed soil-profile. Data from other fine-root investigations suggest turnover rates in agreement with our present findings. Differences between root growth and turnover should be expected between trees of different age, tree species and different forest sites, but also between different years. Substantial variations in fine-root biomass, necromass and live/dead ratios are found in different forest sites. Correct methods for estimating the amount of live and dead fine-roots in the soil at regular time intervals are essential for any calculation of fine-root turnover. Definition of root vitality differs in literature, making it difficult to compare results from different root investigators. Our investigation clarifies the importance of using distinct morphological criteria when

  1. Retinue of the beans roots growth by using neutron radiography technique

    International Nuclear Information System (INIS)

    Agricultural practices frequently cause the development of a soil compacted layer below the surface. These compacted layers restrict the root penetration into deeper layers of soil, in search for water. It is proposed to monitor, using Non Destructive Test, the roots growth due to the planting of standard seeds in different agricultural soils, in function of their compactness and humidity. It will be used the neutrons beams derived from an irradiation channel called J-9 of the Reactor Argonauta (IEN/CNEN), so that the neutron radiographic images of the soil-plant system can be obtained. Each root can be evaluated for its ability to penetrate into compacted soil layers; this fact would mean an optimization of agricultural harvests. (author)

  2. Arabidopsis TWISTED DWARF1 functionally interacts with Auxin Exporter ABCB1 on the root plasma membrane

    DEFF Research Database (Denmark)

    Wang, Bangjun; Bailly, Aurélien; Zwiewka, Marta;

    2013-01-01

    . In planta bioluminescence resonance energy transfer analysis was used to verify specific ABC transporter B1 (ABCB1)-TWD1 interaction. Our data support a model in which TWD1 promotes lateral ABCB-mediated auxin efflux via protein-protein interaction at the plasma membrane, minimizing reflux from the root...

  3. Effects of Phlomis umbrosa Root on Longitudinal Bone Growth Rate in Adolescent Female Rats.

    Science.gov (United States)

    Lee, Donghun; Kim, Young-Sik; Song, Jungbin; Kim, Hyun Soo; Lee, Hyun Jung; Guo, Hailing; Kim, Hocheol

    2016-01-01

    This study aimed to investigate the effects of Phlomis umbrosa root on bone growth and growth mediators in rats. Female adolescent rats were administered P. umbrosa extract, recombinant human growth hormone or vehicle for 10 days. Tetracycline was injected intraperitoneally to produce a glowing fluorescence band on the newly formed bone on day 8, and 5-bromo-2'-deoxyuridine was injected to label proliferating chondrocytes on days 8-10. To assess possible endocrine or autocrine/paracrine mechanisms, we evaluated insulin-like growth factor-1 (IGF-1), insulin-like growth factor binding protein-3 (IGFBP-3) or bone morphogenetic protein-2 (BMP-2) in response to P. umbrosa administration in either growth plate or serum. Oral administration of P. umbrosa significantly increased longitudinal bone growth rate, height of hypertrophic zone and chondrocyte proliferation of the proximal tibial growth plate. P. umbrosa also increased serum IGFBP-3 levels and upregulated the expressions of IGF-1 and BMP-2 in growth plate. In conclusion, P. umbrosa increases longitudinal bone growth rate by stimulating proliferation and hypertrophy of chondrocyte with the increment of circulating IGFBP-3. Regarding the immunohistochemical study, the effect of P. umbrosa may also be attributable to upregulation of local IGF-1 and BMP-2 expressions in the growth plate, which can be considered as a GH dependent autocrine/paracrine pathway. PMID:27070559

  4. Effects of Phlomis umbrosa Root on Longitudinal Bone Growth Rate in Adolescent Female Rats

    Directory of Open Access Journals (Sweden)

    Donghun Lee

    2016-04-01

    Full Text Available This study aimed to investigate the effects of Phlomis umbrosa root on bone growth and growth mediators in rats. Female adolescent rats were administered P. umbrosa extract, recombinant human growth hormone or vehicle for 10 days. Tetracycline was injected intraperitoneally to produce a glowing fluorescence band on the newly formed bone on day 8, and 5-bromo-2′-deoxyuridine was injected to label proliferating chondrocytes on days 8–10. To assess possible endocrine or autocrine/paracrine mechanisms, we evaluated insulin-like growth factor-1 (IGF-1, insulin-like growth factor binding protein-3 (IGFBP-3 or bone morphogenetic protein-2 (BMP-2 in response to P. umbrosa administration in either growth plate or serum. Oral administration of P. umbrosa significantly increased longitudinal bone growth rate, height of hypertrophic zone and chondrocyte proliferation of the proximal tibial growth plate. P. umbrosa also increased serum IGFBP-3 levels and upregulated the expressions of IGF-1 and BMP-2 in growth plate. In conclusion, P. umbrosa increases longitudinal bone growth rate by stimulating proliferation and hypertrophy of chondrocyte with the increment of circulating IGFBP-3. Regarding the immunohistochemical study, the effect of P. umbrosa may also be attributable to upregulation of local IGF-1 and BMP-2 expressions in the growth plate, which can be considered as a GH dependent autocrine/paracrine pathway.

  5. Growth, Root Formation, and Nutrient Value of Triticale Plants Fertilized with Biosolids

    Directory of Open Access Journals (Sweden)

    Wendy Mercedes Rauw

    2012-01-01

    Full Text Available Biosolids are utilized as nutrient rich fertilizer. Little material is available on benefits to forage crops resulting from fertilization with biosolids. This paper aimed to compare the effects of fertilization with biosolids versus commercial nitrogen fertilizer on growth, root formation, and nutrient value of triticale plants in a greenhouse experiment. Per treatment, five pots were seeded with five triticale seeds each. Treatments included a nonfertilized control, fertilization with 100, 200, 300, 400, and 500 ml biosolids per pot, and fertilization with a commercial nitrogen fertilizer at the recommended application rate and at double that rate. Biomass production, root length, root diameter, nitrogen, phosphorus, and potassium concentration were analyzed at harvest. Fertilization with biosolids increased triticale production (P<0.001; production was similar for the 100 to 400 mL treatments. Root length, nitrogen, and phosphorus concentration increased, and potassium concentration decreased linearly with application rate. At the recommended rate, biomass production was similar between fertilization with biosolids and commercial fertilizer. However, plants fertilized with commercial fertilizer had considerably longer roots (P<0.001, higher nitrogen concentration (P<0.05, and lower potassium concentration (P<0.01 than those fertilized with biosolids. Our results indicate that at the recommended application rate, biomass production was similar between fertilization with biosolids and with commercial nitrogen fertilizer, indicating the value of biosolids fertilization as a potential alternative.

  6. Rooting, growth, and color mutation of poinsettias affected by gamma radiation

    International Nuclear Information System (INIS)

    This experiment was carried out to investigate the effects of gamma-radiation on the rooting, growth, and color mutation in poinsettia. Using 10 poinsettia varieties ('Lollipop', 'Little Peace', 'Happy Day', 'Early Bird', 'Pixy Red', 'Happy Time', 'Heidi', 'Red Bell', 'Clara', and 'Scarlet') bred by National Institute of Horticultural and Herbal Science, 100 Gy of gamma ray was irradiated at the stage of callused cuttings. Four weeks after sticking cuttings in the rooting media, 8 cultivars showed 100% of root formation, but 'Early Bird' rooted 24.4% and even died off during the cutting propagation. After planting rooted cuttings, survival rate until flowering time varied among irradiated cultivars. While 'Pixy Red' and 'Heidi' survived about 98%, 'Clara', 'Happy Day', and 'Early Bird' survived lesser than 30%. All irradiated plants showed remarkably shorter plant height, lesser branch numbers than non-irradiated control plants. Thirty color mutants were obtained among 281 plants survived until flowering time. Nine were complete color mutated branches, whereas 21 mutants were partially color mutated bracts and transitional leaves. Color patterns mutated by 100 Gy of gamma ray were divided into pink, hot pink, light red and spotted (pink spots with red main color). Pink mutants were commonly obtained. Complete color mutants were discovered from 4 plants of 'Pixy Red', 2 plants of 'Red Bell' and 3 plants of Lollipop

  7. Live substrate positively affects root growth and stolon direction in the woodland strawberry, Fragaria vesca.

    Science.gov (United States)

    Waters, Erica M; Watson, Maxine A

    2015-01-01

    Studies of clonal plant foraging generally focus on growth responses to patch quality once rooted. Here we explore the possibility of true plant foraging; the ability to detect and respond to patch resource status prior to rooting. Two greenhouse experiments were conducted to investigate the morphological changes that occur when individual daughter ramets of Fragaria vesca (woodland strawberry) were exposed to air above live (non-sterilized) or dead (sterilized) substrates. Contact between daughter ramets and substrate was prohibited. Daughter ramet root biomass was significantly larger over live versus dead substrate. Root:shoot ratio also increased over live substrate, a morphological response we interpret as indicative of active nutrient foraging. Daughter ramet root biomass was positively correlated with mother ramet size over live but not dead substrate. Given the choice between a live versus a dead substrate, primary stolons extended preferentially toward live substrates. We conclude that exposure to live substrate drives positive nutrient foraging responses in F. vesca. We propose that volatiles emitted from the substrates might be effecting the morphological changes that occur during true nutrient foraging. PMID:26483826

  8. Live substrate positively affects root growth and stolon direction in the woodland strawberry, Fragaria vesca

    Directory of Open Access Journals (Sweden)

    Erica Marie Waters

    2015-09-01

    Full Text Available Studies of clonal plant foraging generally focus on growth responses to patch quality once rooted. Here we explore the possibility of true plant foraging; the ability to detect and respond to patch resource status prior to rooting. Two greenhouse experiments were conducted to investigate the morphological changes that occur when individual daughter ramets of Fragaria vesca (woodland strawberry were exposed to air above live (non-sterilized or dead (sterilized substrates. Contact between daughter ramets and substrate was prohibited. Daughter ramet root biomass was significantly larger over live versus dead substrate. Root:shoot ratio also increased over live substrate, a morphological response we interpret as indicative of active nutrient foraging. Daughter ramet root biomass was positively correlated with mother ramet size over live but not dead substrate. Given the choice between a live versus a dead substrate, primary stolons extended preferentially toward live substrates. We conclude that exposure to live substrate drives positive nutrient foraging responses in Fragaria vesca. We propose that volatiles emitted from by the substrates might be effecting the morphological changes that occur during true nutrient foraging.

  9. Comparative transcriptomics as a tool for the identification of root branching genes in maize.

    Science.gov (United States)

    Jansen, Leentje; Hollunder, Jens; Roberts, Ianto; Forestan, Cristian; Fonteyne, Philippe; Van Quickenborne, Charlotte; Zhen, Rui-Guang; McKersie, Bryan; Parizot, Boris; Beeckman, Tom

    2013-12-01

    The root system is fundamental for plant development, is crucial for overall plant growth and is recently being recognized as the key for future crop productivity improvement. A major determinant of root system architecture is the initiation of lateral roots. While knowledge of the genetic and molecular mechanisms regulating lateral root initiation has mainly been achieved in the dicotyledonous plant Arabidopsis thaliana, only scarce data are available for major crop species, generally monocotyledonous plants. The existence of both similarities and differences at the morphological and anatomical level between plant species from both clades raises the question whether regulation of lateral root initiation may or may not be conserved through evolution. Here, we performed a targeted genome-wide transcriptome analysis during lateral root initiation both in primary and in adventitious roots of Zea mays and found evidence for the existence of common transcriptional regulation. Further, based on a comparative analysis with Arabidopsis transcriptome data, a core of genes putatively conserved across angiosperms could be identified. Therefore, it is plausible that common regulatory mechanisms for lateral root initiation are at play in maize and Arabidopsis, a finding that might encourage the extrapolation of knowledge obtained in Arabidopsis to crop species at the level of root system architecture. PMID:23941360

  10. The AUXIN BINDING PROTEIN 1 is required for differential auxin responses mediating root growth.

    Directory of Open Access Journals (Sweden)

    Alexandre Tromas

    Full Text Available BACKGROUND: In plants, the phytohormone auxin is a crucial regulator sustaining growth and development. At the cellular level, auxin is interpreted differentially in a tissue- and dose-dependent manner. Mechanisms of auxin signalling are partially unknown and the contribution of the AUXIN BINDING PROTEIN 1 (ABP1 as an auxin receptor is still a matter of debate. METHODOLOGY/PRINCIPAL FINDINGS: Here we took advantage of the present knowledge of the root biological system to demonstrate that ABP1 is required for auxin response. The use of conditional ABP1 defective plants reveals that the protein is essential for maintenance of the root meristem and acts at least on the D-type CYCLIN/RETINOBLASTOMA pathway to control entry into the cell cycle. ABP1 affects PLETHORA gradients and confers auxin sensitivity to root cells thus defining the competence of the cells to be maintained within the meristem or to elongate. ABP1 is also implicated in the regulation of gene expression in response to auxin. CONCLUSIONS/SIGNIFICANCE: Our data support that ABP1 is a key regulator for root growth and is required for auxin-mediated responses. Differential effects of ABP1 on various auxin responses support a model in which ABP1 is the major regulator for auxin action on the cell cycle and regulates auxin-mediated gene expression and cell elongation in addition to the already well known TIR1-mediated ubiquitination pathway.

  11. Effect of Lanthanum on Rice Growth and Physiological Parameters with Split-Root Nutrient Solution Culture

    Institute of Scientific and Technical Information of China (English)

    谢祖彬; 朱建国; 褚海燕; 张雅丽; 高人; 曾青; 曹志洪

    2003-01-01

    Split-root solution culture was used to study the promoting effect of lanthanum on rice (Oryza sativa) growth and its physiological mechanisms. Results show that low concentration (0.05~1.5 mg*L-1) increases rice yield and grain numbers. High concentration depresses grain formation (9~30 mg*L-1) and root elongation (1.5~30 mg*L-1). No significant influence on straw dry weight was found over the whole concentration range except the 0.05 mg*L-1 treatment. With the increase of La concentration from 0.05 to 0.75 mg*L-1, catalase (CAT) activity in the first fully expandeing leaves and roots decreases. When La concentration is greater than 0.75 mg*L-1 or less than 9 mg*L-1, it significantly decreases superoxide dismutase activity (SOD) in the leaves and roots. No significant effects were found on chlorophyll, protein and malondialdehyde (MDA) content. Possible mechanisms of La′s promoting effect on rice growth and reduction effect of *O-2 were discussed.

  12. Growth of eucalyptus rooted cuttings in toxic organic waste compost of textile industry

    Directory of Open Access Journals (Sweden)

    Priscila F. de Souza

    2015-09-01

    Full Text Available ABSTRACTBiodegradation techniques may help contaminated organic wastes to become useful for plant production. The current study aimed to evaluate the efficiency of composting in the biodegradation of toxic residues from the textile industry and its use as substrate in saplings production. Cotton cloths contaminated with oil and grease, used in loom maintenance, were composted in a mixture with cattle manure. The composted material replaced coconut fiber in the substrate for the production of eucalyptus rooted cuttings: mixture of vermiculite, carbonized rice husk and coconut fiber in the ratio of 2:1:1 (v/v and using it as control. Thus, the amount of rice husks remained unchanged and the amount of vermiculite and compost varied. The compost proportion in the tested substrates were 0, 19, 37, 56 and 75%. The compost produced from textile wastes showed high nutrient levels and low levels of heavy metals. In general, the survival, growth and some growth indices of rooted cuttings produced on substrates with 19 and 37% compost were similar to those of rooted cuttings grown in commercial substrate. Composting is efficient and the material is useful for rooted cuttings production.

  13. Shoot Photosynthesis and Root Growth of Hybrid and Conventional Rice Cultivars as Affected by N and K Levels in the Root Zone

    Institute of Scientific and Technical Information of China (English)

    YANGXIAOE; V.ROEMHELD; 等

    1997-01-01

    Root box experiments were conducted to evaluate the effects of N and NK levels in the root zone on shoot photosynthesis and root growth of hybrid an cultivar of rice (Oryza sativa L.) on two paddy soils (clayey and silty).The results showed that dry matter yields in the hybrid and the cultivar were considerably increased by NK supply,bu the effect was greater for the hybrid.Supply of NK in the root zone significantly increased photosynthetic rate of the lower position leaf and the active green leaf area per plant,in which the effects were much more obvious in the hybrid rice than in the cultivar.High NK supply in the root zone stimulated the root growth,and decreased pH and increased the oxidation zone in the rhizosphere in both entries,but to a greater extent in the hybrid .The results indicated that higher NK levels were needed to maintain higher root activity and shoot photosynthetic capacity in rice,particularly in hybrid rice.

  14. Arabidopsis CDS blastp result: AK111785 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK111785 J023089N11 At5g62310.1 incomplete root hair ... elongation (IRE) / protein kinase, putative ... nearly identical to IRE (incomplete root hair ... elongation) [Arabidopsis thaliana] gi|6729346|dbj| ...

  15. Arabidopsis CDS blastp result: AK243050 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK243050 J100011E04 At5g62310.1 68418.m07822 incomplete root hair ... elongation (IRE) / protein kin ... putative nearly identical to IRE (incomplete root hair ... elongation) [Arabidopsis thaliana] gi|6729346|dbj| ...

  16. Arabidopsis CDS blastp result: AK242758 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK242758 J090051H03 At5g62310.1 68418.m07822 incomplete root hair ... elongation (IRE) / protein kin ... putative nearly identical to IRE (incomplete root hair ... elongation) [Arabidopsis thaliana] gi|6729346|dbj| ...

  17. Arabidopsis CDS blastp result: AK242717 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK242717 J090043H19 At5g62310.1 68418.m07822 incomplete root hair ... elongation (IRE) / protein kin ... putative nearly identical to IRE (incomplete root hair ... elongation) [Arabidopsis thaliana] gi|6729346|dbj| ...

  18. Arabidopsis CDS blastp result: AK288095 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK288095 J075191E21 At5g62310.1 68418.m07822 incomplete root hair ... elongation (IRE) / protein kin ... putative nearly identical to IRE (incomplete root hair ... elongation) [Arabidopsis thaliana] gi|6729346|dbj| ...

  19. Arabidopsis CDS blastp result: AK242638 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK242638 J090023J02 At5g62310.1 68418.m07822 incomplete root hair ... elongation (IRE) / protein kin ... putative nearly identical to IRE (incomplete root hair ... elongation) [Arabidopsis thaliana] gi|6729346|dbj| ...

  20. Arabidopsis CDS blastp result: AK242651 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK242651 J090026B08 At5g62310.1 68418.m07822 incomplete root hair ... elongation (IRE) / protein kin ... putative nearly identical to IRE (incomplete root hair ... elongation) [Arabidopsis thaliana] gi|6729346|dbj| ...

  1. Arabidopsis CDS blastp result: AK287631 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK287631 J065073J24 At5g62310.1 68418.m07822 incomplete root hair ... elongation (IRE) / protein kin ... putative nearly identical to IRE (incomplete root hair ... elongation) [Arabidopsis thaliana] gi|6729346|dbj| ...

  2. Arabidopsis CDS blastp result: AK288923 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK288923 J090081P06 At5g62310.1 68418.m07822 incomplete root hair ... elongation (IRE) / protein kin ... putative nearly identical to IRE (incomplete root hair ... elongation) [Arabidopsis thaliana] gi|6729346|dbj| ...

  3. Arabidopsis CDS blastp result: AK242271 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK242271 J075187A19 At5g62310.1 68418.m07822 incomplete root hair ... elongation (IRE) / protein kin ... putative nearly identical to IRE (incomplete root hair ... elongation) [Arabidopsis thaliana] gi|6729346|dbj| ...

  4. Arabidopsis CDS blastp result: AK242681 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK242681 J090032N04 At5g62310.1 68418.m07822 incomplete root hair ... elongation (IRE) / protein kin ... putative nearly identical to IRE (incomplete root hair ... elongation) [Arabidopsis thaliana] gi|6729346|dbj| ...

  5. Arabidopsis CDS blastp result: AK243656 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK243656 J100088L22 At5g62310.1 68418.m07822 incomplete root hair ... elongation (IRE) / protein kin ... putative nearly identical to IRE (incomplete root hair ... elongation) [Arabidopsis thaliana] gi|6729346|dbj| ...

  6. Arabidopsis CDS blastp result: AK241519 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK241519 J065170E12 At5g62310.1 68418.m07822 incomplete root hair ... elongation (IRE) / protein kin ... putative nearly identical to IRE (incomplete root hair ... elongation) [Arabidopsis thaliana] gi|6729346|dbj| ...

  7. Arabidopsis CDS blastp result: AK240655 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK240655 J023135E11 At5g62310.1 68418.m07822 incomplete root hair ... elongation (IRE) / protein kin ... putative nearly identical to IRE (incomplete root hair ... elongation) [Arabidopsis thaliana] gi|6729346|dbj| ...

  8. Arabidopsis CDS blastp result: AK242733 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK242733 J090047O22 At5g62310.1 68418.m07822 incomplete root hair ... elongation (IRE) / protein kin ... putative nearly identical to IRE (incomplete root hair ... elongation) [Arabidopsis thaliana] gi|6729346|dbj| ...

  9. Arabidopsis CDS blastp result: AK242859 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK242859 J090073L24 At5g62310.1 68418.m07822 incomplete root hair ... elongation (IRE) / protein kin ... putative nearly identical to IRE (incomplete root hair ... elongation) [Arabidopsis thaliana] gi|6729346|dbj| ...

  10. Arabidopsis CDS blastp result: AK243187 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK243187 J100039E11 At5g62310.1 68418.m07822 incomplete root hair ... elongation (IRE) / protein kin ... putative nearly identical to IRE (incomplete root hair ... elongation) [Arabidopsis thaliana] gi|6729346|dbj| ...

  11. Ethylene promotes hyponastic growth through interaction with ROTUNDIFOLIA3/CYP90C1 in Arabidopsis

    Czech Academy of Sciences Publication Activity Database

    Polko, J.; Pierik, R.; Zanten, M.; Tarkowská, Danuše; Strnad, Miroslav; Voesenek, L. A. C. J.; Peeters, A. J. M.

    2013-01-01

    Roč. 64, č. 2 (2013), s. 613-624. ISSN 0022-0957 R&D Projects: GA AV ČR IAA400550801 Grant ostatní: GA MŠk(CZ) ED0007/01/01 Institutional research plan: CEZ:AV0Z50380511 Keywords : Arabidopsis * brassinosteroids * cell expansion Subject RIV: CC - Organic Chemistry Impact factor: 5.794, year: 2013

  12. Genome wide association mapping of time-dependent growth responses to moderate drought stress in Arabidopsis

    OpenAIRE

    Bac-Molenaar, Johanna A.; Granier, Christine; Keurentjes, Joost J.B.; Vreugdenhil, Dick

    2016-01-01

    Large areas of arable land are often confronted with irregular rainfall resulting in limited water availability for part(s) of the growing seasons, which demands research for drought tolerance of plants. Natural variation was observed for biomass accumulation upon controlled moderate drought stress in 324 natural accessions of Arabidopsis. Improved performance under drought stress was correlated with early flowering and lack of vernalization requirement, indicating overlap in the regulatory n...

  13. The role of auxin and ethylene for gravitropic differential growth of coleoptiles and roots of rye- and maize seedlings

    Science.gov (United States)

    Edelmann, H. G.; Sabovljevic, A.; Njio, G.; Roth, U.

    The relevance of auxin and ethylene for differential gravitropic growth has been analyzed both in shoots and roots of etiolated rye- and maize seedlings. As previously demonstrated for indolyl-3-acetic acid (IAA), incubation of coleoptiles in dichlorophenoxy acetic acid (2,4-D) resulted in a two- to threefold length increase compared to water controls. In spite of this immense effect on elongation growth, gravi-curvature was similar to water controls. In contrast, inhibition of ethylene synthesis prevented differential growth of abraded coleoptiles as well as of roots without a significant inhibiting effect on elongation. Inhibition of ethylene perception in horizontally stimulated maize roots growing on surfaces eliminated the capacity of the roots to adapt growth to the surface and a vertical orientation of the root tip. This effect is accompanied by up- and down-regulation of a number of proteins as detected with the 2D-MALDI-TOF (matrix-assisted laser desorption ionization- time of flight) method. Exogenous ethylene inhibited growth but enhanced gravitropic curvature in roots that were "freely" gravistimulated in a horizontal position, exhibiting a pronounced "waving" behavior. Together the data challenge the regulatory relevance of IAA-redistribution for gravitropic differential growth. They corroborate the crucial regulatory relevance of ethylene for gravitropic growth, in both roots and coleoptiles.

  14. Azospirillum brasilense ameliorates the response of Arabidopsis thaliana to drought mainly via enhancement of ABA levels.

    Science.gov (United States)

    Cohen, Ana C; Bottini, Rubén; Pontin, Mariela; Berli, Federico J; Moreno, Daniela; Boccanlandro, Hernán; Travaglia, Claudia N; Piccoli, Patricia N

    2015-01-01

    Production of phytohormones is one of the main mechanisms to explain the beneficial effects of plant growth-promoting rhizobacteria (PGPR) such as Azospirillum sp. The PGPRs induce plant growth and development, and reduce stress susceptibility. However, little is known regarding the stress-related phytohormone abscisic acid (ABA) produced by bacteria. We investigated the effects of Azospirillum brasilense Sp 245 strain on Arabidopsis thaliana Col-0 and aba2-1 mutant plants, evaluating the morphophysiological and biochemical responses when watered and in drought. We used an in vitro-grown system to study changes in the root volume and architecture after inoculation with Azospirillum in Arabidopsis wild-type Col-0 and on the mutant aba2-1, during early growth. To examine Arabidopsis development and reproductive success as affected by the bacteria, ABA and drought, a pot experiment using Arabidopsis Col-0 plants was also carried out. Azospirillum brasilense augmented plant biomass, altered root architecture by increasing lateral roots number, stimulated photosynthetic and photoprotective pigments and retarded water loss in correlation with incremented ABA levels. As well, inoculation improved plants seed yield, plants survival, proline levels and relative leaf water content; it also decreased stomatal conductance, malondialdehyde and relative soil water content in plants submitted to drought. Arabidopsis inoculation with A. brasilense improved plants performance, especially in drought. PMID:24796562

  15. Arabidopsis Serine Decarboxylase Mutants Implicate the Roles of Ethanolamine in Plant Growth and Development

    Directory of Open Access Journals (Sweden)

    Byeong-ha Lee

    2012-03-01

    Full Text Available Ethanolamine is important for synthesis of choline, phosphatidylethanolamine (PE and phosphatidylcholine (PC in plants. The latter two phospholipids are the major phospholipids in eukaryotic membranes. In plants, ethanolamine is mainly synthesized directly from serine by serine decarboxylase. Serine decarboxylase is unique to plants and was previously shown to have highly specific activity to L-serine. While serine decarboxylase was biochemically characterized, its functions and importance in plants were not biologically elucidated due to the lack of serine decarboxylase mutants. Here we characterized an Arabidopsis mutant defective in serine decarboxylase, named atsdc-1 (Arabidopsis thaliana serine decarboxylase-1. The atsdc-1 mutants showed necrotic lesions in leaves, multiple inflorescences, sterility in flower, and early flowering in short day conditions. These defects were rescued by ethanolamine application to atsdc-1, suggesting the roles of ethanolamine as well as serine decarboxylase in plant development. In addition, molecular analysis of serine decarboxylase suggests that Arabidopsis serine decarboxylase is cytosol-localized and expressed in all tissue.

  16. Establishment of embryonic shoot–root axis is involved in auxin and cytokinin response during Arabidopsis somatic embryogenesis

    OpenAIRE

    Su, Ying Hua; Liu, Yu Bo; Bai, Bo; Zhang, Xian Sheng

    2015-01-01

    Auxin and cytokinin signaling participates in regulating a large spectrum of developmental and physiological processes in plants. The shoots and roots of plants have specific and sometimes even contrary responses to these hormones. Recent studies have clearly shown that establishing the spatiotemporal distribution of auxin and cytokinin response signals is central for the control of shoot apical meristem (SAM) induction in cultured tissues. However, little is known about the role of these hor...

  17. Growth and Nutrition of Eucalypt Rooted Cuttings Promoted by Ectomycorrhizal Fungi in Commercial Nurseries

    OpenAIRE

    Andrezza Mara Martins Gandini; Paulo Henrique Grazziotti; Márcio José Rossi; Danielle Cristina Fonseca Santos Grazziotti; Elizzandra Marta Martins Gandini; Enilson de Barros Silva; Carla Ragonezi

    2015-01-01

    ABSTRACT Ectomycorrhizal fungi (EMF) may improve the adaptation of eucalypts saplings to field conditions and allow more efficient fertilizer use. The effectiveness of EMF inoculum application in promoting fungal colonization, plant growth, nutrient uptake, and the quality of rooted cuttings was evaluated forEucalyptus urophylla under commercial nursery conditions. For inoculated treatments, fertilization of the sapling substrate was reduced by 50 %. The experiment was carried out in a comple...

  18. Effect of plant growth regulators on adventitious roots of Panax ginseng

    Czech Academy of Sciences Publication Activity Database

    Langhansová, Lenka; Maršík, Petr; Fišerová, Darina

    Bratislava: IPGB SAS, 2005, s. 25-27. [Final Conference COST 843 and COST 851 Joint Meeting. Stará Lesná (SK), 28.06.2005-03.07.2005] R&D Projects: GA MŠk(CZ) OC 843.10; GA ČR(CZ) GP521/02/P064 Institutional research plan: CEZ:AV0Z4055905 Keywords : Panax ginseng * adventitious roots * growth regulators Subject RIV: CE - Biochemistry

  19. Inhibitory Activity of Yokukansankachimpihange against Nerve Growth Factor-Induced Neurite Growth in Cultured Rat Dorsal Root Ganglion Neurons.

    Science.gov (United States)

    Murayama, Chiaki; Watanabe, Shimpei; Nakamura, Motokazu; Norimoto, Hisayoshi

    2015-01-01

    Chronic pruritus is a major and distressing symptom of many cutaneous diseases, however, the treatment remains a challenge in the clinic. The traditional Chinese-Japanese medicine (Kampo medicine) is a conservative and increasingly popular approach to treat chronic pruritus for both patients and medical providers. Yokukansankachimpihange (YKH), a Kampo formula has been demonstrated to be effective in the treatment of itching of atopic dermatitis in Japan although its pharmacological mechanism is unknown clearly. In an attempt to clarify its pharmacological actions, in this study, we focused on the inhibitory activity of YKH against neurite growth induced with nerve growth factor (NGF) in cultured rat dorsal root ganglion (DRG) neurons because epidermal hyperinnervation is deeply related to itch sensitization. YKH showed approximately 200-fold inhibitory activity against NGF-induced neurite growth than that of neurotropin (positive control), a drug used clinically for treatment of chronic pruritus. Moreover, it also found that Uncaria hook, Bupleurum root and their chemical constituents rhynchophylline, hirsutine, and saikosaponin a, d showed inhibitory activities against NGF-induced neurite growth, suggesting they should mainly contribute to the inhibitory activity of YKH. Further study on the effects of YKH against epidermal nerve density in "itch-scratch" animal models is under investigation. PMID:26287150

  20. Inhibitory Activity of Yokukansankachimpihange against Nerve Growth Factor-Induced Neurite Growth in Cultured Rat Dorsal Root Ganglion Neurons

    Directory of Open Access Journals (Sweden)

    Chiaki Murayama

    2015-08-01

    Full Text Available Chronic pruritus is a major and distressing symptom of many cutaneous diseases, however, the treatment remains a challenge in the clinic. The traditional Chinese-Japanese medicine (Kampo medicine is a conservative and increasingly popular approach to treat chronic pruritus for both patients and medical providers. Yokukansankachimpihange (YKH, a Kampo formula has been demonstrated to be effective in the treatment of itching of atopic dermatitis in Japan although its pharmacological mechanism is unknown clearly. In an attempt to clarify its pharmacological actions, in this study, we focused on the inhibitory activity of YKH against neurite growth induced with nerve growth factor (NGF in cultured rat dorsal root ganglion (DRG neurons because epidermal hyperinnervation is deeply related to itch sensitization. YKH showed approximately 200-fold inhibitory activity against NGF-induced neurite growth than that of neurotropin (positive control, a drug used clinically for treatment of chronic pruritus. Moreover, it also found that Uncaria hook, Bupleurum root and their chemical constituents rhynchophylline, hirsutine, and saikosaponin a, d showed inhibitory activities against NGF-induced neurite growth, suggesting they should mainly contribute to the inhibitory activity of YKH. Further study on the effects of YKH against epidermal nerve density in “itch-scratch” animal models is under investigation.

  1. Polyethylene mulch stimulates early root growth and nutrient uptake of transplanted tomatoes

    Energy Technology Data Exchange (ETDEWEB)

    Wien, H.C.; Minotti, P.L.; Grubinger, V.P. (Cornell Univ., Ithaca, NY (United States). Dept. of Fruit and Vegetable Science)

    1993-03-01

    Tomato (Lycopersicon esculentum Mill.) plants grown on polyethylene (PE) mulch in New York State frequently have more branches and increased mineral nutrient uptake and yield than plants not mulched. In four field experiments conducted on a silt loam soil, clear PE mulch stimulated root extension shortly after transplanting. One week after transplanting, roots were significantly longer for mulched than for unmulched plants in all four experiments, whereas above ground dry matter differences did not become significant until 14 days after transplanting in two of four trials. Mulching increased branching, hastened flowering on basal branches, and increased concentration of major nutrients in the above ground parts. In the field, stimulation of above ground growth due to mulch might be brought about by warming of the stem by air escaping from the planting hole in the mulch. However, an experiment with black, white, or clear mulch, in which the planting hole was either left uncovered or covered with soil, showed no effect of hole closure on branching even though air temperature near the stem was increased when holes were left uncovered. The results taken together imply that the increased above ground growth observed with mulching is a consequence of enhanced root growth and nutrient uptake.

  2. Sulfur nutrient availability regulates root elongation by affecting root indole-3-acetic acid levels and the stem cell niche

    Institute of Scientific and Technical Information of China (English)

    Qing Zhao; Yu Wu; Lei Gao; Jun Ma; Chuan-You Li; Cheng-Bin Xiang

    2014-01-01

    Sulfur is an essential macronutrient for plants with numerous biological functions. However, the influence of sulfur nutrient availability on the regulation of root development remains largely unknown. Here, we report the response of Arabidopsis thaliana L. root development and growth to different levels of sulfate, demonstrating that low sulfate levels promote the primary root elongation. By using various reporter lines, we examined in vivo IAA level and distribution, cel division, and root meristem in response to different sulfate levels. Meanwhile the dynamic changes of in vivo cysteine, glutathione, and IAA levels were measured. Root cysteine, glutathione, and IAA levels are positively correlated with external sulfate levels in the physiological range, which eventual y affect root system architecture. Low sulfate levels also downregulate the genes involved in auxin biosynthesis and transport, and elevate the accumulation of PLT1 and PLT2. This study suggests that sulfate level affects the primary root elongation by regulating the endogenous auxin level and root stem cel niche maintenance.

  3. The Arabidopsis transcriptional regulator DPB3-1 enhances heat stress tolerance without growth retardation in rice.

    Science.gov (United States)

    Sato, Hikaru; Todaka, Daisuke; Kudo, Madoka; Mizoi, Junya; Kidokoro, Satoshi; Zhao, Yu; Shinozaki, Kazuo; Yamaguchi-Shinozaki, Kazuko

    2016-08-01

    The enhancement of heat stress tolerance in crops is an important challenge for food security to facilitate adaptation to global warming. In Arabidopsis thaliana, the transcriptional regulator DNA polymerase II subunit B3-1 (DPB3-1)/nuclear factor Y subunit C10 (NF-YC10) has been reported as a positive regulator of Dehydration-responsive element binding protein 2A (DREB2A), and the overexpression of DPB3-1 enhances heat stress tolerance without growth retardation. Here, we show that DPB3-1 interacts with DREB2A homologues in rice and soya bean. Transactivation analyses with Arabidopsis and rice mesophyll protoplasts indicate that DPB3-1 and its rice homologue OsDPB3-2 function as positive regulators of DREB2A homologues. Overexpression of DPB3-1 did not affect plant growth or yield in rice under nonstress conditions. Moreover, DPB3-1-overexpressing rice showed enhanced heat stress tolerance. Microarray analysis revealed that many heat stress-inducible genes were up-regulated in DPB3-1-overexpressing rice under heat stress conditions. However, the overexpression of DPB3-1 using a constitutive promoter had almost no effect on the expression of these genes under nonstress conditions. This may be because DPB3-1 is a coactivator and thus lacks inherent transcriptional activity. We conclude that DPB3-1, a coactivator that functions specifically under abiotic stress conditions, could be utilized to increase heat stress tolerance in crops without negative effects on vegetative and reproductive growth. PMID:26841113

  4. The relationship between flowering time and growth responses to drought in the Arabidopsis Landsberg erecta x Antwerp-1 population

    Directory of Open Access Journals (Sweden)

    Inga eSchmalenbach

    2014-11-01

    Full Text Available Limited water availability is one of the most prominent abiotic constraints to plant survival and reproduction. Thus, plants have evolved different strategies to cope with water deficit, including modification of their growth and timing of developmental events such as flowering. In this work, we explore the link between flowering time and growth responses to moderate drought stress in Arabidopsis thaliana using natural variation for these traits found in the Landsberg erecta x Antwerp-1 recombinant inbred line population. We developed and phenotyped near isogenic lines containing different allelic combinations at three interacting quantitative trait loci (QTL affecting both flowering time and growth in response to water deficit. We used these lines to confirm additive and epistatic effects of the three QTL and observed a strong association between late flowering and reduced sensitivity to drought. Analyses of growth responses to drought over time revealed that late flowering plants were able to recover their growth in the second half of their vegetative development. In contrast, early flowering, a common drought escape strategy that ensures plant survival under severe water deficit, was associated with strongly impaired plant fitness. The results presented here indicate that late flowering may be advantageous under continuous mild water deficit as it allows stress acclimatization over time.

  5. Time dependence of micronucleus frequency in germinating onion root tip cells and growth decrease of plant's roots irradiated by accelerated heavy ions

    International Nuclear Information System (INIS)

    Micronucleus induction of germinating onion seed root tip cells delayed with increase of radiation dose. The frequency at the time the cells showed the maximum frequency indicated a dose relationship of upward bell shape. Growth decrease of germinating green sorgo seed roots by radiations were severer than onion and it showed also linear energy transfer (LET) dependence like onion. Alphalfa seeds are very strong for radiation, however, finally showed recognizable growth decrease at high dose of 60 Gy, and no LET dependence was found. (author)

  6. High temperatures limit plant growth but hasten flowering in root chicory (Cichorium intybus) independently of vernalisation.

    Science.gov (United States)

    Mathieu, Anne-Sophie; Lutts, Stanley; Vandoorne, Bertrand; Descamps, Christophe; Périlleux, Claire; Dielen, Vincent; Van Herck, Jean-Claude; Quinet, Muriel

    2014-01-15

    An increase in mean and extreme summer temperatures is expected as a consequence of climate changes and this might have an impact on plant development in numerous species. Root chicory (Cichorium intybus L.) is a major crop in northern Europe, and it is cultivated as a source of inulin. This polysaccharide is stored in the tap root during the first growing season when the plant grows as a leafy rosette, whereas bolting and flowering occur in the second year after winter vernalisation. The impact of heat stress on plant phenology, water status, photosynthesis-related parameters, and inulin content was studied in the field and under controlled phytotron conditions. In the field, plants of the Crescendo cultivar were cultivated under a closed plastic-panelled greenhouse to investigate heat-stress conditions, while the control plants were shielded with a similar, but open, structure. In the phytotrons, the Crescendo and Fredonia cultivars were exposed to high temperatures (35°C day/28°C night) and compared to control conditions (17°C) over 10 weeks. In the field, heat reduced the root weight, the inulin content of the root and its degree of polymerisation in non-bolting plants. Flowering was observed in 12% of the heat stressed plants during the first growing season in the field. In the phytotron, the heat stress increased the total number of leaves per plant, but reduced the mean leaf area. Photosynthesis efficiency was increased in these plants, whereas osmotic potential was decreased. High temperature was also found to induced flowering of up to 50% of these plants, especially for the Fredonia cultivar. In conclusion, high temperatures induced a reduction in the growth of root chicory, although photosynthesis is not affected. Flowering was also induced, which indicates that high temperatures can partly substitute for the vernalisation requirement for the flowering of root chicory. PMID:24331425

  7. Stress promotes Arabidopsis - Piriformospora indica interaction.

    Science.gov (United States)

    Vahabi, Khabat; Dorcheh, Sedigheh Karimi; Monajembashi, Shamci; Westermann, Martin; Reichelt, Michael; Falkenberg, Daniela; Hemmerich, Peter; Sherameti, Irena; Oelmüller, Ralf

    2016-05-01

    The endophytic fungus Piriformospora indica colonizes Arabidopsis thaliana roots and promotes plant performance, growth and resistance/tolerance against abiotic and biotic stress. Here we demonstrate that the benefits for the plant increase when the two partners are co-cultivated under stress (limited access to nutrient, exposure to heavy metals and salt, light and osmotic stress, pathogen infection). Moreover, physical contact between P. indica and Arabidopsis roots is necessary for optimal growth promotion, and chemical communication cannot replace the physical contact. Lower nutrient availability down-regulates and higher nutrient availability up-regulates the plant defense system including the expression of pathogenesis-related genes in roots. High light, osmotic and salt stresses support the beneficial interaction between the plant and the fungus. P. indica reduces stomata closure and H2O2 production after Alternaria brassicae infection in leaves and suppresses the defense-related accumulation of the phytohormone jasmonic acid. Thus, shifting the growth conditions toward a stress promotes the mutualistic interaction, while optimal supply with nutrients or low stress diminishes the benefits for the plant in the symbiosis. PMID:27167761

  8. Root growth of Lotus corniculatus interacts with P distribution in young sandy soil

    OpenAIRE

    R. Schulin; R. F. J. Hüttl; Schneider, B.U.; K. M. Boldt-Burisch; Felderer, B.

    2012-01-01

    Large areas of land are restored with un-weathered soil substrates following mining activities in eastern Germany and elsewhere. In the initial stages of colonization of such land by vegetation, plant roots may become key agents in generating soil formation patterns by introducing gradients in chemical and physical soil properties. On the other hand, such patterns may be influenced by root growth responses to pre-existing substrate heterogeneities. In particular, the roots of many plants were...

  9. Net root growth and nutrient acquisition in response to predicted climate change in two contrasting heathland species

    DEFF Research Database (Denmark)

    Arndal, M.F.; Merrild, M.P.; Michelsen, A.;

    2013-01-01

    colonization, and fine root N and P uptake by root assay of Deschampsia flexuosa and Calluna vulgaris.Net root growth increased under elevated CO2, warming and drought, with additive effects among the factors. Arbuscular mycorrhizal colonization increased in response to elevated CO2, while ericoid mycorrhizal...... colonization was unchanged. The uptake of N and P was not increased proportionally with root growth after 5 years of treatment.While aboveground biomass was unchanged, the root growth was increased under elevated CO2. The results suggest that plant production may be limited by N (but not P) when exposed...... to elevated CO2. The species-specific response to the treatments suggests different sensitivity to global change factors, which could result in changed plant competitive interactions and belowground nutrient pool sizes in response to future climate change....

  10. PATTERN OF ROOTING AND GROWTH OF CUTTINGS OF SOME SPECIES OF INSECTICIDAL AND MEDICINAL IMPORTANCE AS AFFECTED BY GROWTH PROMOTING SUBSTANCES

    OpenAIRE

    Obi, E.A; Aiyelari, O..P; Agele , S.O

    2013-01-01

    This study was designed to examine the effects of promoting substances on bud retention, rooting and plantlets survival of rooted cuttings on selected tree species using growth promoting substances. Stem cuttings were treated with rooting-promoting substances, planted in plastic pots filled with top soil and arranged using a completely randomized design (CRD) in a screen house. Stem cuttings of pepper fruit, guava, bush mango and cashew were obtained from the Teaching and Research Farm, Feder...

  11. Nutritional regulation of root development.

    Science.gov (United States)

    Ruiz Herrera, León Francisco; Shane, Michael W; López-Bucio, José

    2015-01-01

    Mineral nutrients such as nitrogen (N), phosphorus (P), and iron (Fe) are essential for plant growth, development, and reproduction. Adequate provision of nutrients via the root system impacts greatly on shoot biomass and plant productivity and is therefore of crucial importance for agriculture. Nutrients are taken up at the root surface in ionic form, which is mediated by specific transport proteins. Noteworthy, root tips are able to sense the local and internal concentrations of nutrients to adjust growth and developmental processes, and ultimately, to increase or decrease the exploratory capacity of the root system. Recently, important progress has been achieved in identifying the mechanisms of nutrient sensing in wild- and cultivated species, including Arabidopsis, bean, maize, rice, lupin as well as in members of the Proteaceae and Cyperaceae families, which develop highly sophisticated root clusters as adaptations to survive in soils with very low fertility. Major findings include identification of transporter proteins and transcription factors regulating nutrient sensing, miRNAs as mobile signals and peptides as repressors of lateral root development under heterogeneous nutrient supply. Understanding the roles played by N, P, and Fe in gene expression and biochemical characterization of proteins involved in root developmental responses to homogeneous or heterogeneous N and P sources has gained additional interest due to its potential for improving fertilizer acquisition efficiency in crops. PMID:25760021

  12. Influences of Root Zone Restriction and Nitrogen Nutrition on Hybrid Wheat Growth

    Institute of Scientific and Technical Information of China (English)

    ZHANGRONGIAN; SHENZHENGUO; 等

    1997-01-01

    To study the physiological effects of small root zone,plants of a hybrid wheat variety(Triticum aestivum L.cv.Meiyou 4) were grown in small pots(1 litre)or large pots(8 litre) with low nitrogen(50 mg kg-1 soil) and high nitrogen(200 mg kg-1 soil).Restricting root zone decreased dry weight of plants at the stages of stem elongation and flowering ,compared to those of control plants grown in the large pots(P<0.01).Spraying of 6-benzylaminopurine(50 μmol L01) increased dry weight of plants and chlorophyll concentration in leaves. restriction of root zone decreased the concentrations of total nitrogen,chlorophyll and soluble protein in the flag leaf and accelerated senescence of the leaves,Supply of high nitrogen delayed senescence of the flag leaf.The results suggested that the shortage of nutrients ,especially nitrogen deficiency,was the primary reason for the decreased growth of plant in the treatment of root zone restriction.

  13. Growth stimulation of ectomycorrhizal fungi by root exudates of Brassicaceae plants: role of degraded compounds of indole glucosinolates.

    Science.gov (United States)

    Zeng, Ren Sen; Mallik, Azim U; Setliff, Ed

    2003-06-01

    Brassicaceae plants are nonmycorrhizal. They were found to inhibit VA mycorrhizal infection in their host plants. We tested if they can influence growth of ectomycorrhizal (ECM) fungi. When roots and leaves of Brassicaceae plants and ECM fungi were cultured together in the same petri dishes, the root exudates of turnip (Brassica rapa), swede (B. napobrassica), cabbage (B. oleracea, var. capitata), broccoli (B. oleracea, var. italica Plenck), kohlrobi (B. caulorapa Pasq.), mustard (B. juncea), radish (Raphanus sativus), and choy (B. napus) significantly stimulated hyphal growth of the ectomycorrhizal fungus Paxillus involutus. Root exudates of turnip and cabbage stimulated hyphal growth of Pisolithus tinctorius and two isolates of P. involutus. Colony area of P. involutus was increased by 452 and 414%, respectively, in the presence of turnip and cabbage germinants. Root exudates of turnip increased the biomass of P. involutus and P. tinctorius by 256 and 122% and cabbage by 220 and 82%, respectively. The stimulatory effect was not affected by autoclaving the root exudates. Root exudates had chemical reactions with glutathione and lysine, which resulted in a reduction of the growth stimulation of ECM fungi. Myrosinase enhanced further the stimulatory effects of turnip on the ECM colony diameter growth by 23%. Autoclaved roots and leaves of turnip did not stimulate fungal growth, but mechanically ground roots and leaves of turnip stimulated growth of P. involutus by 147 and 135%, respectively. After desulfuration with aryl sulphatuse, the glucosinolates (GLSs) in turnip roots and leaves were identified by HPLC. The major ones were indole GLSs. Prominent compounds identified were 1-methoxy-3-indolymethyl GLS and4-methoxy-3-indolymethyl GLS. The finding provides an opportunity to field test the use of Brassicaceae plants in enhancing ectomycorrhizal formation in conifers by interplanting conifers with Brassicaceae plants in forest tree nursery and agroforestry systems

  14. Computer based imaging and analysis of root gravitropism

    Science.gov (United States)

    Evans, M. L.; Ishikawa, H.

    1997-01-01

    Two key issues in studies of the nature of the gravitropic response in roots have been the determination of the precise pattern of differential elongation responsible for downward bending and the identification of the cells that show the initial motor response. The main approach for examining patterns of differential growth durin