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Sample records for tip-growing arabidopsis cells

  1. Functional analysis of the cellulose synthase-like genes CSLD1, CSLD2 and CSLD4 in tip-growing arabidopsis cells

    DEFF Research Database (Denmark)

    Bernal Giraldo, Adriana Jimena; Yoo, Cheol-Min; Mutwil, Marek

    2008-01-01

    A reverse genetic approach was used to investigate the functions of three members of the cellulose synthase superfamily in Arabidopsis (Arabidopsis thaliana), CELLULOSE SYNTHASE-LIKE D1 (CSLD1), CSLD2, and CSLD4. CSLD2 is required for normal root hair growth but has a different role from that pre......A reverse genetic approach was used to investigate the functions of three members of the cellulose synthase superfamily in Arabidopsis (Arabidopsis thaliana), CELLULOSE SYNTHASE-LIKE D1 (CSLD1), CSLD2, and CSLD4. CSLD2 is required for normal root hair growth but has a different role from...... for insertions in these genes were partially rescued by reduced temperature growth. However, this was not the case for a double mutant homozygous for insertions in both CSLD2 and CSLD3, suggesting that there may be partial redundancy in the functions of these genes. Mutants in CSLD1 and CSLD4 had a defect...

  2. The Mechanism Forming the Cell Surface of Tip-Growing Rooting Cells Is Conserved among Land Plants.

    Science.gov (United States)

    Honkanen, Suvi; Jones, Victor A S; Morieri, Giulia; Champion, Clement; Hetherington, Alexander J; Kelly, Steve; Proust, Hélène; Saint-Marcoux, Denis; Prescott, Helen; Dolan, Liam

    2016-12-05

    To discover mechanisms that controlled the growth of the rooting system in the earliest land plants, we identified genes that control the development of rhizoids in the liverwort Marchantia polymorpha. 336,000 T-DNA transformed lines were screened for mutants with defects in rhizoid growth, and a de novo genome assembly was generated to identify the mutant genes. We report the identification of 33 genes required for rhizoid growth, of which 6 had not previously been functionally characterized in green plants. We demonstrate that members of the same orthogroup are active in cell wall synthesis, cell wall integrity sensing, and vesicle trafficking during M. polymorpha rhizoid and Arabidopsis thaliana root hair growth. This indicates that the mechanism for constructing the cell surface of tip-growing rooting cells is conserved among land plants and was active in the earliest land plants that existed sometime more than 470 million years ago [1, 2]. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  3. An oligogalacturonide-derived molecular probe demonstrates the dynamics of calcium-mediated pectin complexation in cell walls of tip-growing structures

    DEFF Research Database (Denmark)

    Mravec, Jozef; Kracun, Stjepan Kresimir; Rydahl, Maja Gro

    2017-01-01

    walls and in mediating cell-to-cell adhesion. Current immunological methods enable only steady-state detection of egg box formation in situ. Here we present a tool for efficient real-time visualisation of available sites for HG crosslinking within cell wall microdomains. Our approach is based on calcium-mediated...... thermodynamic model. Using defined carbohydrate microarrays, we show that the long OG probe binds exclusively to HG that has a very low degree of esterification and in the presence of divalent ions. We used this probe to study real-time dynamics of HG during elongation of Arabidopsis pollen tubes and root hairs...

  4. A role for CSLD3 during cell-wall synthesis in apical plasma membranes of tip-growing root-hair cells.

    Science.gov (United States)

    Park, Sungjin; Szumlanski, Amy L; Gu, Fangwei; Guo, Feng; Nielsen, Erik

    2011-07-17

    In plants, cell shape is defined by the cell wall, and changes in cell shape and size are dictated by modification of existing cell walls and deposition of newly synthesized cell-wall material. In root hairs, expansion occurs by a process called tip growth, which is shared by root hairs, pollen tubes and fungal hyphae. We show that cellulose-like polysaccharides are present in root-hair tips, and de novo synthesis of these polysaccharides is required for tip growth. We also find that eYFP-CSLD3 proteins, but not CESA cellulose synthases, localize to a polarized plasma-membrane domain in root hairs. Using biochemical methods and genetic complementation of a csld3 mutant with a chimaeric CSLD3 protein containing a CESA6 catalytic domain, we provide evidence that CSLD3 represents a distinct (1→4)-β-glucan synthase activity in apical plasma membranes during tip growth in root-hair cells.

  5. Knockin' on pollen's door: live cell imaging of early polarization events in germinating Arabidopsis pollen

    Science.gov (United States)

    Vogler, Frank; Konrad, Sebastian S. A.; Sprunck, Stefanie

    2015-01-01

    Pollen tubes are an excellent system for studying the cellular dynamics and complex signaling pathways that coordinate polarized tip growth. Although several signaling mechanisms acting in the tip-growing pollen tube have been described, our knowledge on the subcellular and molecular events during pollen germination and growth site selection at the pollen plasma membrane is rather scarce. To simultaneously track germinating pollen from up to 12 genetically different plants we developed an inexpensive and easy mounting technique, suitable for every standard microscope setup. We performed high magnification live-cell imaging during Arabidopsis pollen activation, germination, and the establishment of pollen tube tip growth by using fluorescent marker lines labeling either the pollen cytoplasm, vesicles, the actin cytoskeleton or the sperm cell nuclei and membranes. Our studies revealed distinctive vesicle and F-actin polarization during pollen activation and characteristic growth kinetics during pollen germination and pollen tube formation. Initially, the germinating Arabidopsis pollen tube grows slowly and forms a uniform roundish bulge, followed by a transition phase with vesicles heavily accumulating at the growth site before switching to rapid tip growth. Furthermore, we found the two sperm cells to be transported into the pollen tube after the phase of rapid tip growth has been initiated. The method presented here is suitable to quantitatively study subcellular events during Arabidopsis pollen germination and growth, and for the detailed analysis of pollen mutants with respect to pollen polarization, bulging, or growth site selection at the pollen plasma membrane. PMID:25954283

  6. Knockin’ on pollen’s door: live cell imaging of early polarization events in germinating Arabidopsis pollen

    Directory of Open Access Journals (Sweden)

    Frank eVogler

    2015-04-01

    Full Text Available Pollen tubes are an excellent system for studying the cellular dynamics and complex signaling pathways that coordinate polarized tip growth. Although several signaling mechanisms acting in the tip-growing pollen tube have been described, our knowledge on the subcellular and molecular events during pollen germination and growth site selection at the pollen plasma membrane is rather scarce. To simultaneously track germinating pollen from up to 12 genetically different plants we developed an inexpensive and easy mounting technique, suitable for every standard microscope setup. We performed high magnification live-cell imaging during Arabidopsis pollen activation, germination, and the establishment of pollen tube tip growth by using fluorescent marker lines labeling either the pollen cytoplasm, vesicles, the actin cytoskeleton or the sperm cell nuclei and membranes. Our studies revealed distinctive vesicle and F-actin polarization during pollen activation and characteristic growth kinetics during pollen germination and pollen tube formation. Initially, the germinating Arabidopsis pollen tube grows slowly and forms a uniform roundish bulge, followed by a transition phase with vesicles heavily accumulating at the growth site before switching to rapid tip growth. Furthermore, we found the two sperm cells to be transported into the pollen tube after the phase of rapid tip growth has been initiated. The method presented here is suitable to quantitatively study subcellular events during Arabidopsis pollen germination and growth, and for the detailed analysis of pollen mutants with respect to pollen polarization, bulging, or growth site selection at the pollen plasma membrane.

  7. Stem cell organization in Arabidopsis

    NARCIS (Netherlands)

    Wendrich, J.R.

    2016-01-01

    Growth of plant tissues and organs depends on continuous production of new cells, by niches of stem cells. Stem cells typically divide to give rise to one differentiating daughter and one non-differentiating daughter. This constant process of self-renewal ensures that the niches of stem cells or

  8. Structure and organ specificity of an anionic peroxidase from Arabidopsis thaliana cell suspension culture

    DEFF Research Database (Denmark)

    Ostergaard, L; Abelskov, A K; Mattsson, O

    1996-01-01

    The predominant peroxidase (pI 3.5) (E.C. 1.11.1.7) of an Arabidopsis thaliana cell suspension culture was purified and partially sequenced. Oligonucleotides were designed and a specific probe was obtained. A cDNA clone was isolated from an Arabidopsis cell suspension cDNA library and completely ...

  9. Live cell imaging of Arabidopsis root hairs

    NARCIS (Netherlands)

    Ketelaar, T.

    2014-01-01

    Root hairs are tubular extensions from the root surface that expand by tip growth. This highly focused type of cell expansion, combined with position of root hairs on the surface of the root, makes them ideal cells for microscopic observation. This chapter describes the method that is routinely used

  10. Regulation of Floral Stem Cell Termination in Arabidopsis

    Directory of Open Access Journals (Sweden)

    Toshiro eIto

    2015-02-01

    Full Text Available In Arabidopsis, floral stem cells are maintained only at the initial stages of flower development, and they are terminated at a specific time to ensure proper development of the reproductive organs. Floral stem cell termination is a dynamic and multi-step process involving many transcription factors, chromatin remodeling factors and signaling pathways. In this review, we discuss the mechanisms involved in floral stem cell maintenance and termination, highlighting the interplay between transcriptional regulation and epigenetic machinery in the control of specific floral developmental genes. In addition, we discuss additional factors involved in floral stem cell regulation, with the goal of untangling the complexity of the floral stem cell regulatory network.

  11. Autophagic components contribute to hypersensitive cell death in Arabidopsis

    DEFF Research Database (Denmark)

    Hofius, Daniel; Schultz-Larsen, Torsten; Joensen, Jan

    2009-01-01

    Autophagy has been implicated as a prosurvival mechanism to restrict programmed cell death (PCD) associated with the pathogen-triggered hypersensitive response (HR) during plant innate immunity. This model is based on the observation that HR lesions spread in plants with reduced autophagy gene...... expression. Here, we examined receptor-mediated HR PCD responses in autophagy-deficient Arabidopsis knockout mutants (atg), and show that infection-induced lesions are contained in atg mutants. We also provide evidence that HR cell death initiated via Toll/Interleukin-1 (TIR)-type immune receptors through...... the defense regulator EDS1 is suppressed in atg mutants. Furthermore, we demonstrate that PCD triggered by coiled-coil (CC)-type immune receptors via NDR1 is either autophagy-independent or engages autophagic components with cathepsins and other unidentified cell death mediators. Thus, autophagic cell death...

  12. Multimodal nonlinear imaging of arabidopsis thaliana root cell

    Science.gov (United States)

    Jang, Bumjoon; Lee, Sung-Ho; Woo, Sooah; Park, Jong-Hyun; Lee, Myeong Min; Park, Seung-Han

    2017-07-01

    Nonlinear optical microscopy has enabled the possibility to explore inside the living organisms. It utilizes ultrashort laser pulse with long wavelength (greater than 800nm). Ultrashort pulse produces high peak power to induce nonlinear optical phenomenon such as two-photon excitation fluorescence (TPEF) and harmonic generations in the medium while maintaining relatively low average energy pre area. In plant developmental biology, confocal microscopy is widely used in plant cell imaging after the development of biological fluorescence labels in mid-1990s. However, fluorescence labeling itself affects the sample and the sample deviates from intact condition especially when labelling the entire cell. In this work, we report the dynamic images of Arabidopsis thaliana root cells. This demonstrates the multimodal nonlinear optical microscopy is an effective tool for long-term plant cell imaging.

  13. Isolation of plasmodesmata from Arabidopsis suspension culture cells.

    Science.gov (United States)

    Grison, Magali S; Fernandez-Calvino, Lourdes; Mongrand, Sébastien; Bayer, Emmanuelle M F

    2015-01-01

    Due to their position firmly anchored within the plant cell wall, plasmodesmata (PD) are notoriously difficult to isolate from plant tissue. Yet, getting access to isolated PD represents the most straightforward strategy for the identification of their molecular components. Proteomic and lipidomic analyses of such PD fractions have provided and will continue to provide critical information on the functional and structural elements that define these membranous nano-pores. Here, we describe a two-step simple purification procedure that allows isolation of pure PD-derived membranes from Arabidopsis suspension cells. The first step of this procedure consists in isolating cell wall fragments containing intact PD while free of contamination from other cellular compartments. The second step relies on an enzymatic degradation of the wall matrix and the subsequent release of "free" PD. Isolated PD membranes provide a suitable starting material for the analysis of PD-associated proteins and lipids.

  14. The FRIABLE1 gene product affects cell adhesion in Arabidopsis.

    Directory of Open Access Journals (Sweden)

    Lutz Neumetzler

    Full Text Available Cell adhesion in plants is mediated predominantly by pectins, a group of complex cell wall associated polysaccharides. An Arabidopsis mutant, friable1 (frb1, was identified through a screen of T-DNA insertion lines that exhibited defective cell adhesion. Interestingly, the frb1 plants displayed both cell and organ dissociations and also ectopic defects in organ separation. The FRB1 gene encodes a Golgi-localized, plant specific protein with only weak sequence similarities to known proteins (DUF246. Unlike other cell adhesion deficient mutants, frb1 mutants do not have reduced levels of adhesion related cell wall polymers, such as pectins. Instead, FRB1 affects the abundance of galactose- and arabinose-containing oligosaccharides in the Golgi. Furthermore, frb1 mutants displayed alteration in pectin methylesterification, cell wall associated extensins and xyloglucan microstructure. We propose that abnormal FRB1 action has pleiotropic consequences on wall architecture, affecting both the extensin and pectin matrices, with consequent changes to the biomechanical properties of the wall and middle lamella, thereby influencing cell-cell adhesion.

  15. Nuclear and cellular expression data from the whole 16-cell stage Arabidopsis thaliana embryo and a cell type-specific expression atlas of the early Arabidopsis embryo

    NARCIS (Netherlands)

    Palovaara, J.P.J.

    2017-01-01

    SuperSeries contain expression data from the nuclei of cell types involved in patterning events, with focus on root apical stem cell formation, at 16-cell stage, early globular stage and late globular stage in the early Arabidopsis embryo (atlas). Expression data comparing nuclear and cellular RNA

  16. Diclofenac in Arabidopsis cells: Rapid formation of conjugates.

    Science.gov (United States)

    Fu, Qiuguo; Ye, Qingfu; Zhang, Jianbo; Richards, Jaben; Borchardt, Dan; Gan, Jay

    2017-03-01

    Pharmaceutical and personal care products (PPCPs) are continuously introduced into the soil-plant system, through practices such as agronomic use of reclaimed water and biosolids containing these trace contaminants. Plants may accumulate PPCPs from soil, serving as a conduit for human exposure. Metabolism likely controls the final accumulation of PPCPs in plants, but is in general poorly understood for emerging contaminants. In this study, we used diclofenac as a model compound, and employed 14 C tracing, and time-of-flight (TOF) and triple quadruple (QqQ) mass spectrometers to unravel its metabolism pathways in Arabidopsis thaliana cells. We further validated the primary metabolites in Arabidopsis seedlings. Diclofenac was quickly taken up into A. thaliana cells. Phase I metabolism involved hydroxylation and successive oxidation and cyclization reactions. However, Phase I metabolites did not accumulate appreciably; they were instead rapidly conjugated with sulfate, glucose, and glutamic acid through Phase II metabolism. In particular, diclofenac parent was directly conjugated with glutamic acid, with acyl-glutamatyl-diclofenac accounting for >70% of the extractable metabolites after 120-h incubation. In addition, at the end of incubation, >40% of the spiked diclofenac was in the non-extractable form, suggesting extensive sequestration into cell matter. The rapid formation of non-extractable residue and dominance of diclofenac-glutamate conjugate uncover previously unknown metabolism pathways for diclofenac. In particular, the rapid conjugation of parent highlights the need to consider conjugates of emerging contaminants in higher plants, and their biological activity and human health implications. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Promoter DNA hypermethylation and gene repression in undifferentiated Arabidopsis cells.

    Directory of Open Access Journals (Sweden)

    María Berdasco

    Full Text Available Maintaining and acquiring the pluripotent cell state in plants is critical to tissue regeneration and vegetative multiplication. Histone-based epigenetic mechanisms are important for regulating this undifferentiated state. Here we report the use of genetic and pharmacological experimental approaches to show that Arabidopsis cell suspensions and calluses specifically repress some genes as a result of promoter DNA hypermethylation. We found that promoters of the MAPK12, GSTU10 and BXL1 genes become hypermethylated in callus cells and that hypermethylation also affects the TTG1, GSTF5, SUVH8, fimbrin and CCD7 genes in cell suspensions. Promoter hypermethylation in undifferentiated cells was associated with histone hypoacetylation and primarily occurred at CpG sites. Accordingly, we found that the process specifically depends on MET1 and DRM2 methyltransferases, as demonstrated with DNA methyltransferase mutants. Our results suggest that promoter DNA methylation may be another important epigenetic mechanism for the establishment and/or maintenance of the undifferentiated state in plant cells.

  18. Allyl isothiocyanate affects the cell cycle of Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Signe Elisabeth Åsberg

    2015-05-01

    Full Text Available Isothiocyanates (ITCs are degradation products of glucosinolates present in members of the Brassicaceae family acting as herbivore repellents and antimicrobial compounds. Recent results indicate that allyl ITC (AITC has a role in defense responses such as glutathione depletion, ROS generation and stomatal closure. In this study we show that exposure to non-lethal concentrations of AITC causes a shift in the cell cycle distribution of Arabidopsis thaliana leading to accumulation of cells in S-phases and a reduced number of cells in non-replicating phases. Furthermore, transcriptional analysis revealed an AITC-induced up-regulation of the gene encoding cyclin-dependent kinase A while several genes encoding mitotic proteins were down-regulated, suggesting an inhibition of mitotic processes. Interestingly, visualization of DNA synthesis indicated that exposure to AITC reduced the rate of DNA replication. Taken together, these results indicate that non-lethal concentrations of AITC induce cells of A. thaliana to enter the cell cycle and accumulate in S-phases, presumably as a part of a defensive response. Thus, this study suggests that AITC has several roles in plant defense and add evidence to the growing data supporting a multifunctional role of glucosinolates and their degradation products in plants.

  19. The Arabidopsis synaptotagmin SYTA regulates the cell-to-cell movement of diverse plant viruses

    Directory of Open Access Journals (Sweden)

    Asako eUchiyama

    2014-11-01

    Full Text Available Synaptotagmins are a large gene family in animals that have been extensively characterized due to their role as calcium sensors to regulate synaptic vesicle exocytosis and endocytosis in neurons, and dense core vesicle exocytosis for hormone secretion from neuroendocrine cells. Thought to be exclusive to animals, synaptotagmins have recently been characterized in Arabidopsis thaliana, in which they comprise a five gene family. Using infectivity and leaf-based functional assays, we have shown that Arabidopsis SYTA regulates endocytosis and marks an endosomal vesicle recycling pathway to regulate movement protein-mediated trafficking of the Begomovirus Cabbage leaf curl virus (CaLCuV and the Tobamovirus Tobacco mosaic virus (TMV through plasmodesmata (Lewis and Lazarowitz, 2010. To determine whether SYTA has a central role in regulating the cell-to-cell trafficking of a wider range of diverse plant viruses, we extended our studies here to examine the role of SYTA in the cell-to-cell movement of additional plant viruses that employ different modes of movement, namely the Potyvirus Turnip mosaic virus (TuMV, the Caulimovirus Cauliflower mosaic virus (CaMV and the Tobamovirus Turnip vein clearing virus (TVCV, which in contrast to TMV does efficiently infect Arabidopsis. We found that both TuMV and TVCV systemic infection, and the cell-to-cell trafficking of the their movement proteins, were delayed in the Arabidopsis Col-0 syta-1 knockdown mutant. In contrast, CaMV systemic infection was not inhibited in syta-1. Our studies show that SYTA is a key regulator of plant virus intercellular movement, being necessary for the ability of diverse cell-to-cell movement proteins encoded by Begomoviruses (CaLCuV MP, Tobamoviruses (TVCV and TMV 30K protein and Potyviruses (TuMV P3N-PIPO to alter PD and thereby mediate virus cell-to-cell spread.

  20. Arabidopsis FH1 Formin Affects Cotyledon Pavement Cell Shape by Modulating Cytoskeleton Dynamics

    Czech Academy of Sciences Publication Activity Database

    Rosero, A.; Oulehlová, Denisa; Stillerová, L.; Schiebertová, P.; Gunt, M.; Žárský, Viktor; Cvrčková, F.

    2016-01-01

    Roč. 57, č. 3 (2016), s. 488-504 ISSN 0032-0781 Institutional support: RVO:61389030 Keywords : Arabidopsis thaliana * Confocal microscopy * Cotyledon pavement cells Subject RIV: ED - Physiology Impact factor: 4.760, year: 2016

  1. An Arabidopsis kinase cascade influences auxin-responsive cell expansion.

    Science.gov (United States)

    Enders, Tara A; Frick, Elizabeth M; Strader, Lucia C

    2017-10-01

    Mitogen-activated protein kinase (MPK) cascades are conserved mechanisms of signal transduction across eukaryotes. Despite the importance of MPK proteins in signaling events, specific roles for many Arabidopsis MPK proteins remain unknown. Multiple studies have suggested roles for MPK signaling in a variety of auxin-related processes. To identify MPK proteins with roles in auxin response, we screened mpk insertional alleles and identified mpk1-1 as a mutant that displays hypersensitivity in auxin-responsive cell expansion assays. Further, mutants defective in the upstream MAP kinase kinase MKK3 also display hypersensitivity in auxin-responsive cell expansion assays, suggesting that this MPK cascade affects auxin-influenced cell expansion. We found that MPK1 interacts with and phosphorylates ROP BINDING PROTEIN KINASE 1 (RBK1), a protein kinase that interacts with members of the Rho-like GTPases from Plants (ROP) small GTPase family. Similar to mpk1-1 and mkk3-1 mutants, rbk1 insertional mutants display auxin hypersensitivity, consistent with a possible role for RBK1 downstream of MPK1 in influencing auxin-responsive cell expansion. We found that RBK1 directly phosphorylates ROP4 and ROP6, supporting the possibility that RBK1 effects on auxin-responsive cell expansion are mediated through phosphorylation-dependent modulation of ROP activity. Our data suggest a MKK3 • MPK1 • RBK1 phosphorylation cascade that may provide a dynamic module for altering cell expansion. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

  2. Growing Arabidopsis in vitro: cell suspensions, in vitro culture, and regeneration.

    Science.gov (United States)

    Barkla, Bronwyn J; Vera-Estrella, Rosario; Pantoja, Omar

    2014-01-01

    An understanding of basic methods in Arabidopsis tissue culture is beneficial for any laboratory working on this model plant. Tissue culture refers to the aseptic growth of cells, organs, or plants in a controlled environment, in which physical, nutrient, and hormonal conditions can all be easily manipulated and monitored. The methodology facilitates the production of a large number of plants that are genetically identical over a relatively short growth period. Techniques, including callus production, cell suspension cultures, and plant regeneration, are all indispensable tools for the study of cellular biochemical and molecular processes. Plant regeneration is a key technology for successful stable plant transformation, while cell suspension cultures can be exploited for metabolite profiling and mining. In this chapter we report methods for the successful and highly efficient in vitro regeneration of plants and production of stable cell suspension lines from leaf explants of both Arabidopsis thaliana and Arabidopsis halleri.

  3. RIMA-dependent nuclear accumulation of IYO triggers auxin-irreversible cell differentiation in arabidopsis

    NARCIS (Netherlands)

    Muñoz, Alfonso; Mangano, Silvina; González-García, Mary Paz; Contreras, Ramón; Sauer, Michael; Rybel, De Bert; Weijers, Dolf; Sánchez-Serrano, José Juan; Sanmartín, Maite; Rojo, Enrique

    2017-01-01

    The transcriptional regulator MINIYO (IYO) is essential and rate-limiting for initiating cell differentiation in Arabidopsis thaliana. Moreover, IYO moves from the cytosol into the nucleus in cells at the meristem periphery, possibly triggering their differentiation. However, the genetic mechanisms

  4. Human GLTP and mutant forms of ACD11 suppress cell death in the Arabidopsis acd11 mutant

    DEFF Research Database (Denmark)

    Petersen, Nikolaj H T; McKinney, Lea V; Pike, Helen

    2008-01-01

    The Arabidopsis acd11 mutant exhibits runaway, programmed cell death due to the loss of a putative sphingosine transfer protein (ACD11) with homology to mammalian GLTP. We demonstrate that transgenic expression in Arabidopsis thaliana of human GLTP partially suppressed the phenotype of the acd11...

  5. Coordinated Regulations of mRNA Synthesis and Decay during Cold Acclimation in Arabidopsis Cells.

    KAUST Repository

    Arae, Toshihiro; Isai, Shiori; Sakai, Akira; Mineta, Katsuhiko; Hirai, Masami Yokota; Suzuki, Yuya; Kanaya, Shigehiko; Yamaguchi, Junji; Naito, Satoshi; Chiba, Yukako

    2017-01-01

    stress in Arabidopsis cell cultures based on genome-wide analysis. In this mRNA decay array method, mRNA half-life measurements and microarray analyses were combined. In addition, temporal changes in the integrated value of transcription rates were

  6. CYCP2;1 integrates genetic and nutritional information to promote meristem cell division in Arabidopsis

    Czech Academy of Sciences Publication Activity Database

    Peng, L.; Skylar, A.; Chang, P.L.; Bišová, Kateřina; Wu, X.

    2014-01-01

    Roč. 393, č. 2 (2014), s. 160-170 ISSN 0012-1606 R&D Projects: GA AV ČR M200201205 Grant - others:NSF(US) MCB-1122213 Institutional support: RVO:61388971 Keywords : cell cycle * arabidopsis * meristem Subject RIV: EE - Microbiology, Virology Impact factor: 3.547, year: 2014

  7. Induction of cell death by graphene in Arabidopsis thaliana (Columbia ecotype) T87 cell suspensions

    International Nuclear Information System (INIS)

    Begum, Parvin; Fugetsu, Bunshi

    2013-01-01

    Highlights: • This study was set up to explore potential influence of graphene on T87 cells. • Fragmented nuclei, membrane damage, mitochondrial dysfunction were observed. • ROS increased, ROS are key mediators in the cell death signaling pathway. • Translocation of graphene into cells and an endocytosis-like structure was observed. • Graphene entering into the cells by endocytosis. -- Abstract: The toxicity of graphene on suspensions of Arabidopsis thaliana (Columbia ecotype) T87 cells was investigated by examining the morphology, mitochondrial dysfunction, reactive oxygen species generation (ROS), and translocation of graphene as the toxicological endpoints. The cells were grown in Jouanneau and Péaud-Lenoel (JPL) media and exposed to graphene at concentrations 0–80 mg/L. Morphological changes were observed by scanning electron microscope and the adverse effects such as fragmented nuclei, membrane damage, mitochondrial dysfunction was observed with fluorescence microscopy by staining with Hoechst 33342/propidium iodide and succinate dehydrogenase (mitochondrial bioenergetic enzyme). Analysis of intracellular ROS by 2′,7′-dichlorofluorescein diacetate demonstrated that graphene induced a 3.3-fold increase in ROS, suggesting that ROS are key mediators in the cell death signaling pathway. Transmission electron microscopy verified the translocation of graphene into cells and an endocytosis-like structure was observed which suggested graphene entering into the cells by endocytosis. In conclusion, our results show that graphene induced cell death in T87 cells through mitochondrial damage mediated by ROS

  8. High Concentration of Melatonin Regulates Leaf Development by Suppressing Cell Proliferation and Endoreduplication in Arabidopsis.

    Science.gov (United States)

    Wang, Qiannan; An, Bang; Shi, Haitao; Luo, Hongli; He, Chaozu

    2017-05-05

    N -acetyl-5-methoxytryptamine (Melatonin), as a crucial messenger in plants, functions in adjusting biological rhythms, stress tolerance, plant growth and development. Several studies have shown the retardation effect of exogenous melatonin treatment on plant growth and development. However, the in vivo role of melatonin in regulating plant leaf growth and the underlying mechanism are still unclear. In this study, we found that high concentration of melatonin suppressed leaf growth in Arabidopsis by reducing both cell size and cell number. Further kinetic analysis of the fifth leaves showed that melatonin remarkably inhibited cell division rate. Additionally, flow cytometic analysis indicated that melatonin negatively regulated endoreduplication during leaf development. Consistently, the expression analysis revealed that melatonin regulated the transcriptional levels of key genes of cell cycle and ribosome. Taken together, this study suggests that high concentration of melatonin negatively regulated the leaf growth and development in Arabidopsis , through modulation of endoreduplication and the transcripts of cell cycle and ribosomal key genes.

  9. Regulation of Arabidopsis Early Anther Development by Putative Cell-Cell Signaling Molecules and Transcriptional Regulators

    Institute of Scientific and Technical Information of China (English)

    Yu-Jin Sun; Carey LH Hord; Chang-Bin Chen; Hong Ma

    2007-01-01

    Anther development in flowering plants involves the formation of several cell types, including the tapetal and pollen mother cells. The use of genetic and molecular tools has led to the identification and characterization of genes that are critical for normal cell division and differentiation in Arabidopsis early anther development. We review here several recent studies on these genes, including the demonstration that the putative receptor protein kinases BAM1 and BAM2 together play essential roles in the control of early cell division and differentiation. In addition, we discuss the hypothesis that BAM1/2 may form a positive-negative feedback regulatory loop with a previously identified key regulator, SPOROCYTELESS (also called NOZZLE),to control the balance between sporogenous and somatic cell types in the anther. Furthermore, we summarize the isolation and functional analysis of the DYSFUNCTIONAL TAPETUM1 (DYT1) gene in promoting proper tapetal cell differentiation. Our finding that DYT1 encodes a putative transcription factor of the bHLH family, as well as relevant expression analyses, strongly supports a model that DYT1 serves as a critical link between upstream factors and downstream target genes that are critical for normal tapetum development and function. These studies, together with other recently published works, indicate that cell-cell communication and transcriptional control are key processes essential for cell fate specification in anther development.

  10. Catalase and NO CATALASE ACTIVITY1 Promote Autophagy-Dependent Cell Death in Arabidopsis

    DEFF Research Database (Denmark)

    Hackenberg, Thomas; Juul, Trine Maxel; Auzina, Aija

    2013-01-01

    Programmed cell death often depends on generation of reactive oxygen species, which can be detoxified by antioxidative enzymes, including catalases. We previously isolated catalase-deficient mutants (cat2) in a screen for resistance to hydroxyurea-induced cell death. Here, we identify...... an Arabidopsis thaliana hydroxyurea-resistant autophagy mutant, atg2, which also shows reduced sensitivity to cell death triggered by the bacterial effector avrRpm1. To test if catalase deficiency likewise affected both hydroxyurea and avrRpm1 sensitivity, we selected mutants with extremely low catalase...... activities and showed that they carried mutations in a gene that we named NO CATALASE ACTIVITY1 (NCA1). nca1 mutants showed severely reduced activities of all three catalase isoforms in Arabidopsis, and loss of NCA1 function led to strong suppression of RPM1-triggered cell death. Basal and starvation...

  11. Propidium iodide competes with Ca(2+) to label pectin in pollen tubes and Arabidopsis root hairs.

    Science.gov (United States)

    Rounds, Caleb M; Lubeck, Eric; Hepler, Peter K; Winship, Lawrence J

    2011-09-01

    We have used propidium iodide (PI) to investigate the dynamic properties of the primary cell wall at the apex of Arabidopsis (Arabidopsis thaliana) root hairs and pollen tubes and in lily (Lilium formosanum) pollen tubes. Our results show that in root hairs, as in pollen tubes, oscillatory peaks in PI fluorescence precede growth rate oscillations. Pectin forms the primary component of the cell wall at the tip of both root hairs and pollen tubes. Given the electronic structure of PI, we investigated whether PI binds to pectins in a manner analogous to Ca(2+) binding. We first show that Ca(2+) is able to abrogate PI growth inhibition in a dose-dependent manner. PI fluorescence itself also relies directly on the amount of Ca(2+) in the growth solution. Exogenous pectin methyl esterase treatment of pollen tubes, which demethoxylates pectins, freeing more Ca(2+)-binding sites, leads to a dramatic increase in PI fluorescence. Treatment with pectinase leads to a corresponding decrease in fluorescence. These results are consistent with the hypothesis that PI binds to demethoxylated pectins. Unlike other pectin stains, PI at low yet useful concentration is vital and specifically does not alter the tip-focused Ca(2+) gradient or growth oscillations. These data suggest that pectin secretion at the apex of tip-growing plant cells plays a critical role in regulating growth, and PI represents an excellent tool for examining the role of pectin and of Ca(2+) in tip growth.

  12. Reconstitution of a secondary cell wall in a secondary cell wall-deficient Arabidopsis mutant.

    Science.gov (United States)

    Sakamoto, Shingo; Mitsuda, Nobutaka

    2015-02-01

    The secondary cell wall constitutes a rigid frame of cells in plant tissues where rigidity is required. Deposition of the secondary cell wall in fiber cells contributes to the production of wood in woody plants. The secondary cell wall is assembled through co-operative activities of many enzymes, and their gene expression is precisely regulated by a pyramidal cascade of transcription factors. Deposition of a transmuted secondary cell wall in empty fiber cells by expressing selected gene(s) in this cascade has not been attempted previously. In this proof-of-concept study, we expressed chimeric activators of 24 transcription factors that are preferentially expressed in the stem, in empty fiber cells of the Arabidopsis nst1-1 nst3-1 double mutant, which lacks a secondary cell wall in fiber cells, under the control of the NST3 promoter. The chimeric activators of MYB46, SND2 and ANAC075, as well as NST3, reconstituted a secondary cell wall with different characteristics from those of the wild type in terms of its composition. The transgenic lines expressing the SND2 or ANAC075 chimeric activator showed increased glucose and xylose, and lower lignin content, whereas the transgenic line expressing the MYB46 chimeric activator showed increased mannose content. The expression profile of downstream genes in each transgenic line was also different from that of the wild type. This study proposed a new screening strategy to identify factors of secondary wall formation and also suggested the potential of the artificially reconstituted secondary cell walls as a novel raw material for production of bioethanol and other chemicals. © The Author 2014. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists.

  13. Chloroplast Dysfunction Causes Multiple Defects in Cell Cycle Progression in the Arabidopsis crumpled leaf Mutant

    KAUST Repository

    Hudik, Elodie

    2014-07-18

    The majority of research on cell cycle regulation is focused on the nuclear events that govern the replication and segregation of the genome between the two daughter cells. However, eukaryotic cells contain several compartmentalized organelles with specialized functions, and coordination among these organelles is required for proper cell cycle progression, as evidenced by the isolation of several mutants in which both organelle function and overall plant development were affected. To investigate how chloroplast dysfunction affects the cell cycle, we analyzed the crumpled leaf (crl) mutant of Arabidopsis (Arabidopsis thaliana), which is deficient for a chloroplastic protein and displays particularly severe developmental defects. In the crl mutant, we reveal that cell cycle regulation is altered drastically and that meristematic cells prematurely enter differentiation, leading to reduced plant stature and early endoreduplication in the leaves. This response is due to the repression of several key cell cycle regulators as well as constitutive activation of stress-response genes, among them the cell cycle inhibitor SIAMESE-RELATED5. One unique feature of the crl mutant is that it produces aplastidic cells in several organs, including the root tip. By investigating the consequence of the absence of plastids on cell cycle progression, we showed that nuclear DNA replication occurs in aplastidic cells in the root tip, which opens future research prospects regarding the dialogue between plastids and the nucleus during cell cycle regulation in higher plants.

  14. The importance of Arabidopsis glutathione peroxidase 8 for protecting Arabidopsis plant and E. coli cells against oxidative stress.

    Science.gov (United States)

    Gaber, Ahmed

    2014-01-01

    Glutathione peroxidases (GPXs) are major family of the reactive oxygen species (ROS) scavenging enzymes. Recently, database analysis of the Arabidopsis genome revealed a new open-reading frame, thus increasing the total number of AtGPX gene family to eight (AtGPX1-8). The effect of plant hormones like; i. e. salicylic acid (SA), jasmonic acid (JA), abscisic acid (ABA), indoleacetic acid (IAA), and mannitol on the expression of the genes confirm that the AtGPX genes family is regulated by multiple signaling pathways. The survival rate of AtGPX8 knockout plants (KO8) was significantly decreased under heat stress compared with the wild type. Moreover, the content of malondialdehyde (MDA) and protein oxidation was significantly increased in the KO8 plant cells under heat stress. Results indicating that the deficiency of AtGPX8 accelerates the progression of oxidative stress in KO8 plants. On the other hand, the overexpression of AtGPX8 in E. coli cells enhance the growth of the recombinant enzyme on media supplemented with 0.2 mM cumene hydroperoxide, 0.3 mM H 2O 2 or 600 mM NaCl.

  15. 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.

  16. Affinity Purification and Characterization of Functional Tubulin from Cell Suspension Cultures of Arabidopsis and Tobacco1

    Science.gov (United States)

    Fujita, Satoshi; Uchimura, Seiichi; Noguchi, Masahiro; Demura, Taku

    2016-01-01

    Microtubules assemble into several distinct arrays that play important roles in cell division and cell morphogenesis. To decipher the mechanisms that regulate the dynamics and organization of this versatile cytoskeletal component, it is essential to establish in vitro assays that use functional tubulin. Although plant tubulin has been purified previously from protoplasts by reversible taxol-induced polymerization, a simple and efficient purification method has yet to be developed. Here, we used a Tumor Overexpressed Gene (TOG) column, in which the tubulin-binding domains of a yeast (Saccharomyces cerevisiae) TOG homolog are immobilized on resin, to isolate functional plant tubulin. We found that several hundred micrograms of pure tubulin can readily be purified from cell suspension cultures of tobacco (Nicotiana tabacum) and Arabidopsis (Arabidopsis thaliana). The tubulin purified by the TOG column showed high assembly competence, partly because of low levels of polymerization-inhibitory phosphorylation of α-tubulin. Compared with porcine brain tubulin, Arabidopsis tubulin is highly dynamic in vitro at both the plus and minus ends, exhibiting faster shrinkage rates and more frequent catastrophe events, and exhibits frequent spontaneous nucleation. Furthermore, our study shows that an internal histidine tag in α-tubulin can be used to prepare particular isotypes and specifically engineered versions of α-tubulin. In contrast to previous studies of plant tubulin, our mass spectrometry and immunoblot analyses failed to detect posttranslational modification of the isolated Arabidopsis tubulin or detected only low levels of posttranslational modification. This novel technology can be used to prepare assembly-competent, highly dynamic pure tubulin from plant cell cultures. PMID:26747285

  17. Metabolism of ibuprofen in higher plants: A model Arabidopsis thaliana cell suspension culture system

    Czech Academy of Sciences Publication Activity Database

    Maršík, Petr; Šíša, Miroslav; Lacina, O.; Moťková, Kateřina; Langhansová, Lenka; Rezek, Jan; Vaněk, Tomáš

    2017-01-01

    Roč. 220, JAN (2017), s. 383-392 ISSN 0269-7491 R&D Projects: GA ČR(CZ) GA14-22593S Grant - others:European Regional Development Fund(XE) CZ.2.16/3.1.00/24014 Institutional support: RVO:61389030 Keywords : Arabidopsis thaliana * Ibuprofen * Metabolism * Plant cells * Sequestration Subject RIV: CE - Biochemistry OBOR OECD: Plant sciences, botany Impact factor: 5.099, year: 2016

  18. Arabidopsis EST1/SMG7-like protein is a novel regulator of meiotic cell cycle progression

    Czech Academy of Sciences Publication Activity Database

    Riehs, N.; Akimcheva, S.; Bulánková, P.; Idol, R.; Široký, Jiří; Shippen, D.; Schweizer, D.; Říha, K.

    2007-01-01

    Roč. 274, č. 1 (2007), s. 71 ISSN 1742-464X. [32nd FEBS Congress - Molecular Machines. 07.07.2007-12.07.2007, Vienna] R&D Projects: GA ČR(CZ) GA522/06/0380 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : meiosis * Arabidopsis * cell cycle Subject RIV: BO - Biophysics

  19. Loss of CDKC;2 increases both cell division and drought tolerance in Arabidopsis thaliana.

    Science.gov (United States)

    Zhao, Lina; Li, Yaqiong; Xie, Qi; Wu, Yaorong

    2017-09-01

    Drought stress is one of the abiotic stresses that limit plant growth and agricultural productivity. To further understand the mechanism of drought tolerance and identify the genes involved in this process, a genetic screen for altered drought response was conducted in Arabidopsis. One mutant with enhanced drought tolerance was isolated and named Arabidopsis drought tolerance mutant 1 (atdtm1), which has larger lateral organs, prolonged growth duration, increased relative water content and a reduced leaf stomatal density compared with the wild type. The loss of AtDTM1 increases cell division during leaf development. The phenotype is caused by the loss of a T-DNA tagged gene encoding CYCLIN-DEPENDENT KINASE C;2 (CDKC;2), which functions in the regulation of transcription by influencing the phosphorylation status of RNA polymerase II (Pol II). Here, we show that CDKC;2 affects the transcription of downstream genes such as cell cycle genes and genes involved in stomatal development, resulting in altered plant organ size as well as drought tolerance of the plant. These results reveal the crucial role of CDKC;2 in modulating both cell division and the drought response in Arabidopsis. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

  20. Restricted cell elongation in Arabidopsis hypocotyls is associated with a reduced average pectin esterification level.

    Science.gov (United States)

    Derbyshire, Paul; McCann, Maureen C; Roberts, Keith

    2007-06-17

    Cell elongation is mainly limited by the extensibility of the cell wall. Dicotyledonous primary (growing) cell walls contain cellulose, xyloglucan, pectin and proteins, but little is known about how each polymer class contributes to the cell wall mechanical properties that control extensibility. We present evidence that the degree of pectin methyl-esterification (DE%) limits cell growth, and that a minimum level of about 60% DE is required for normal cell elongation in Arabidopsis hypocotyls. When the average DE% falls below this level, as in two gibberellic acid (GA) mutants ga1-3 and gai, and plants expressing pectin methyl-esterase (PME1) from Aspergillus aculeatus, then hypocotyl elongation is reduced. Low average levels of pectin DE% are associated with reduced cell elongation, implicating PMEs, the enzymes that regulate DE%, in the cell elongation process and in responses to GA. At high average DE% other components of the cell wall limit GA-induced growth.

  1. Redox Changes During the Cell Cycle in the Embryonic Root Meristem of Arabidopsis thaliana.

    Science.gov (United States)

    de Simone, Ambra; Hubbard, Rachel; de la Torre, Natanael Viñegra; Velappan, Yazhini; Wilson, Michael; Considine, Michael J; Soppe, Wim J J; Foyer, Christine H

    2017-12-20

    The aim of this study was to characterize redox changes in the nuclei and cytosol occurring during the mitotic cell cycle in the embryonic roots of germinating Arabidopsis seedlings, and to determine how redox cycling was modified in mutants with a decreased capacity for ascorbate synthesis. Using an in vivo reduction-oxidation (redox) reporter (roGFP2), we show that transient oxidation of the cytosol and the nuclei occurred at G1 in the synchronized dividing cells of the Arabidopsis root apical meristem, with reduction at G2 and mitosis. This redox cycle was absent from low ascorbate mutants in which nuclei were significantly more oxidized than controls. The cell cycle-dependent increase in nuclear size was impaired in the ascorbate-deficient mutants, which had fewer cells per unit area in the root proliferation zone. The transcript profile of the dry seeds and size of the imbibed seeds was strongly influenced by low ascorbate but germination, dormancy release and seed aging characteristics were unaffected. These data demonstrate the presence of a redox cycle within the plant cell cycle and that the redox state of the nuclei is an important factor in cell cycle progression. Controlled oxidation is a key feature of the early stages of the plant cell cycle. However, sustained mild oxidation restricts nuclear functions and impairs progression through the cell cycle leading to fewer cells in the root apical meristem. Antioxid. Redox Signal. 27, 1505-1519.

  2. Cell wall heterogeneity in root development of Arabidopsis

    Directory of Open Access Journals (Sweden)

    Marc Somssich

    2016-08-01

    Full Text Available 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 signalling 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-modelling to developmental stages of root cells, and dissect how root cell walls respond to certain environmental changes.

  3. Profilin-Dependent Nucleation and Assembly of Actin Filaments Controls Cell Elongation in Arabidopsis1[OPEN

    Science.gov (United States)

    Cao, Lingyan; Blanchoin, Laurent; Staiger, Christopher J.

    2016-01-01

    Actin filaments in plant cells are incredibly dynamic; they undergo incessant remodeling and assembly or disassembly within seconds. These dynamic events are choreographed by a plethora of actin-binding proteins, but the exact mechanisms are poorly understood. Here, we dissect the contribution of Arabidopsis (Arabidopsis thaliana) PROFILIN1 (PRF1), a conserved actin monomer-binding protein, to actin organization and single filament dynamics during axial cell expansion of living epidermal cells. We found that reduced PRF1 levels enhanced cell and organ growth. Surprisingly, we observed that the overall frequency of nucleation events in prf1 mutants was dramatically decreased and that a subpopulation of actin filaments that assemble at high rates was reduced. To test whether profilin cooperates with plant formin proteins to execute actin nucleation and rapid filament elongation in cells, we used a pharmacological approach. Here, we used Small Molecule Inhibitor of Formin FH2 (SMIFH2), after validating its mode of action on a plant formin in vitro, and observed a reduced nucleation frequency of actin filaments in live cells. Treatment of wild-type epidermal cells with SMIFH2 mimicked the phenotype of prf1 mutants, and the nucleation frequency in prf1-2 mutant was completely insensitive to these treatments. Our data provide compelling evidence that PRF1 coordinates the stochastic dynamic properties of actin filaments by modulating formin-mediated actin nucleation and assembly during plant cell expansion. PMID:26574597

  4. Identification of novel transcription factors regulating secondary cell wall formation in Arabidopsis

    Directory of Open Access Journals (Sweden)

    Hua eCassan-Wang

    2013-06-01

    Full Text Available The presence of lignin in secondary cell walls (SCW is a major factor preventing hydrolytic enzymes from gaining access to cellulose, thereby limiting the saccharification potential of plant biomass. To understand how lignification is regulated is a prerequisite for selecting plant biomass better adapted to bioethanol production. Because transcriptional regulation is a major mechanism controlling the expression of genes involved in lignin biosynthesis, our aim was to identify novel transcription factors dictating lignin profiles in the model plant Arabidopsis. To this end, we have developed a post-genomic approach by combining four independent in-house SCW-related transcriptome datasets obtained from (i the fiber cell wall-deficient wat1 Arabidopsis mutant, (ii Arabidopsis lines over-expressing either the master regulatory activator EgMYB2 or (iii the repressor EgMYB1 and finally (iv Arabidopsis orthologs of Eucalyptus xylem-expressed genes. This allowed us to identify 502 up- or down-regulated transcription factors. We preferentially selected those present in more than one dataset and further analyzed their in silico expression patterns as an additional selection criteria. This selection process led to 80 candidates. Notably, 16 of them were already proven to regulate SCW formation, thereby validating the overall strategy. Then, we phenotyped 43 corresponding mutant lines focusing on histological observations of xylem and interfascicular fibers. This phenotypic screen revealed six mutant lines exhibiting altered lignification patterns. Two of them (blh6 and a zinc finger transcription factor presented hypolignified SCW. Three others (myb52, myb-like TF, hb5 showed hyperlignified SCW whereas the last one (hb15 showed ectopic lignification. In addition, our meta-analyses highlighted a reservoir of new potential regulators adding to the gene network regulating SCW but also opening new avenues to ultimately improve SCW composition for biofuel

  5. Ethylene Inhibits Cell Proliferation of the Arabidopsis Root Meristem1[OPEN

    Science.gov (United States)

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

    2015-01-01

    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. Cell fate in the Arabidopsis root meristem determined by directional signalling.

    Science.gov (United States)

    van den Berg, C; Willemsen, V; Hage, W; Weisbeek, P; Scheres, B

    1995-11-02

    Postembryonic development in plants is achieved by apical meristems. Surgical studies and clonal analysis have revealed indirectly that cells in shoot meristems have no predictable destiny and that position is likely to play a role in the acquisition of cell identity. In contrast to animal systems, there has been no direct evidence for inductive signalling in plants until now. Here we present evidence for such signalling using laser ablation of cells in the root meristem of Arabidopsis thaliana. Although these cells show rigid clonal relationships, we now demonstrate that it is positional control that is most important in the determination of cell fate. Positional signals can be perpetuated from more mature to initial cells to guide the pattern of meristem cell differentiation. This offers an alternative to the general opinion that meristems are the source of patterning information.

  7. Pectinous cell wall thickenings formation - A common defense strategy of plants to cope with Pb.

    Science.gov (United States)

    Krzesłowska, Magdalena; Rabęda, Irena; Basińska, Aneta; Lewandowski, Michał; Mellerowicz, Ewa J; Napieralska, Anna; Samardakiewicz, Sławomir; Woźny, Adam

    2016-07-01

    Lead, one of the most abundant and hazardous trace metals affecting living organisms, has been commonly detected in plant cell walls including some tolerant plants, mining ecotypes and hyperaccumulators. We have previously shown that in tip growing Funaria sp. protonemata cell wall is remodeled in response to lead by formation of thickenings rich in low-methylesterified pectins (pectin epitope JIM5 - JIM5-P) able to bind metal ions, which accumulate large amounts of Pb. Hence, it leads to the increase of cell wall capacity for Pb compartmentalization. Here we show that diverse plant species belonging to different phyla (Arabidopsis, hybrid aspen, star duckweed), form similar cell wall thickenings in response to Pb. These thickenings are formed in tip growing cells such as the root hairs, and in diffuse growing cells such as meristematic and root cap columella cells of root apices in hybrid aspen and Arabidopsis and in mesophyll cells in star duckweed fronds. Notably, all analyzed cell wall thickenings were abundant in JIM5-P and accumulated high amounts of Pb. In addition, the co-localization of JIM5-P and Pb commonly occurred in these cells. Hence, cell wall thickenings formed the extra compartment for Pb accumulation. In this way plant cells increased cell wall capacity for compartmentalization of this toxic metal, protecting protoplast from its toxicity. As cell wall thickenings occurred in diverse plant species and cell types differing in the type of growth we may conclude that pectinous cell wall thickenings formation is a widespread defense strategy of plants to cope with Pb. Moreover, detection of natural defense strategy, increasing plant cell walls capacity for metal accumulation, reveals a promising direction for enhancing plant efficiency in phytoremediation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Role of chromatin factors in Arabidopsis root stem cell maintenance

    NARCIS (Netherlands)

    Kornet, N.G.

    2008-01-01

    Stem cells replenish the cells present in an organism throughout its lifetime and sustain growth. They have unique characteristics: the capability to self-renew and the potential to differentiate into several cell types. Recently, it has become clear that chromatin factors support these unique

  9. Molecular mechanisms controlling pavement cell shape in Arabidopsis leaves.

    Science.gov (United States)

    Qian, Pingping; Hou, Suiwen; Guo, Guangqin

    2009-08-01

    Pavement cells have an interlocking jigsaw puzzle-shaped leaf surface pattern. Twenty-three genes involved in the pavement cell morphogenesis were discovered until now. The mutations of these genes through various means lead to pavement cell shape defects, such as loss or lack of interdigitation, the reduction of lobing, gaps between lobe and neck regions in pavement cells, and distorted trichomes. These phenotypes are affected by the organization of microtubules and microfilaments. Microtubule bands are considered corresponding with the neck regions of the cell, while lobe formation depends on patches of microfilaments. The pathway of Rho of plant (ROP) GTPase signaling cascades regulates overall activity of the cytoskeleton in pavement cells. Some other proteins, in addition to the ROPs, SCAR/WAVE, and ARP2/3 complexes, are also involved in the pavement cell morphogenesis.

  10. Xyloglucan Deficiency Disrupts Microtubule Stability and Cellulose Biosynthesis in Arabidopsis, Altering Cell Growth and Morphogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Chaowen; Zhang, Tian; Zheng, Yunzhen; Cosgrove, Daniel J.; Anderson, Charles T.

    2015-11-02

    Xyloglucan constitutes most of the hemicellulose in eudicot primary cell walls and functions in cell wall structure and mechanics. Although Arabidopsis (Arabidopsis thaliana) xxt1 xxt2 mutants lacking detectable xyloglucan are viable, they display growth defects that are suggestive of alterations in wall integrity. To probe the mechanisms underlying these defects, we analyzed cellulose arrangement, microtubule patterning and dynamics, microtubule- and wall-integrity-related gene expression, and cellulose biosynthesis in xxt1 xxt2 plants. We found that cellulose is highly aligned in xxt1 xxt2 cell walls, that its three-dimensional distribution is altered, and that microtubule patterning and stability are aberrant in etiolated xxt1 xxt2 hypocotyls. We also found that the expression levels of microtubule-associated genes, such as MAP70-5 and CLASP, and receptor genes, such as HERK1 and WAK1, were changed in xxt1 xxt2 plants and that cellulose synthase motility is reduced in xxt1 xxt2 cells, corresponding with a reduction in cellulose content. Our results indicate that loss of xyloglucan affects both the stability of the microtubule cytoskeleton and the production and patterning of cellulose in primary cell walls. These findings establish, to our knowledge, new links between wall integrity, cytoskeletal dynamics, and wall synthesis in the regulation of plant morphogenesis.

  11. Arabidopsis GRI is involved in the regulation of cell death induced by extracellular ROS.

    Science.gov (United States)

    Wrzaczek, Michael; Brosché, Mikael; Kollist, Hannes; Kangasjärvi, Jaakko

    2009-03-31

    Reactive oxygen species (ROS) have important functions in plant stress responses and development. In plants, ozone and pathogen infection induce an extracellular oxidative burst that is involved in the regulation of cell death. However, very little is known about how plants can perceive ROS and regulate the initiation and the containment of cell death. We have identified an Arabidopsis thaliana protein, GRIM REAPER (GRI), that is involved in the regulation of cell death induced by extracellular ROS. Plants with an insertion in GRI display an ozone-sensitive phenotype. GRI is an Arabidopsis ortholog of the tobacco flower-specific Stig1 gene. The GRI protein appears to be processed in leaves with a release of an N-terminal fragment of the protein. Infiltration of the N-terminal fragment of the GRI protein into leaves caused cell death in a superoxide- and salicylic acid-dependent manner. Analysis of the extracellular GRI protein yields information on how plants can initiate ROS-induced cell death during stress response and development.

  12. Effect of nickel on the organization of actin filaments in Arabidopsis thaliana primary root cells

    International Nuclear Information System (INIS)

    Goryunova, I.I.; Krasilenko, Yu.A.; Emets, A.I.; Blyum, Ya.B.

    2016-01-01

    The influence of one of the most toxic heavy metals - nickel (Ni 2+ ) - on the organization of actin filaments (microfilaments) of different types of Arabidopsis thaliana (L.) root cells is studied in living cells by the laser scanning microscopy. To visualize microfilaments, the A. thaliana line expressing chimeric gene gfp-fabd2 was used. Ni 2+ leads to a significant inhibition of the growth of the main root and disturbs its morphology, causing the swelling of epidermal cells and inducing a large number of abnormally long root hairs. For the first time, it has been shown that Ni 2+ disturbs the organization of actin filaments in cells, leading to morphological changes of a root as the main organ, being the first exposed to the intoxication by soil pollutants. It is found that the most sensitive to its action are actin filaments of epidermal cells of all growth zones of A. thaliana root

  13. Expression of Arabidopsis hexokinase in citrus guard cells controls stomatal aperture and reduces transpiration

    Directory of Open Access Journals (Sweden)

    Nitsan eLugassi

    2015-12-01

    Full Text Available Hexokinase (HXK is a sugar-phosphorylating enzyme involved in sugar-sensing. It has recently been shown that HXK in guard cells mediates stomatal closure and coordinates photosynthesis with transpiration in the annual species tomato and Arabidopsis. To examine the role of HXK in the control of the stomatal movement of perennial plants, we generated citrus plants that express Arabidopsis HXK1 (AtHXK1 under KST1, a guard cell-specific promoter. The expression of KST1 in the guard cells of citrus plants has been verified using GFP as a reporter gene. The expression of AtHXK1 in the guard cells of citrus reduced stomatal conductance and transpiration with no negative effect on the rate of photosynthesis, leading to increased water-use efficiency. The effects of light intensity and humidity on stomatal behavior were examined in rooted leaves of the citrus plants. The optimal intensity of photosynthetically active radiation and lower humidity enhanced stomatal closure of AtHXK1-expressing leaves, supporting the role of sugar in the regulation of citrus stomata. These results suggest that HXK coordinates photosynthesis and transpiration and stimulates stomatal closure not only in annual species, but also in perennial species.

  14. Chloroplast behaviour and interactions with other organelles in Arabidopsis thaliana pavement cells.

    Science.gov (United States)

    Barton, Kiah A; Wozny, Michael R; Mathur, Neeta; Jaipargas, Erica-Ashley; Mathur, Jaideep

    2018-01-29

    Chloroplasts are a characteristic feature of green plants. Mesophyll cells possess the majority of chloroplasts and it is widely believed that, with the exception of guard cells, the epidermal layer in most higher plants does not contain chloroplasts. However, recent observations on Arabidopsis thaliana have shown a population of chloroplasts in pavement cells that are smaller than mesophyll chloroplasts and have a high stroma to grana ratio. Here, using stable transgenic lines expressing fluorescent proteins targeted to the plastid stroma, plasma membrane, endoplasmic reticulum, tonoplast, nucleus, mitochondria, peroxisomes, F-actin and microtubules, we characterize the spatiotemporal relationships between the pavement cell chloroplasts (PCCs) and their subcellular environment. Observations on the PCCs suggest a source-sink relationship between the epidermal and the mesophyll layers, and experiments with the Arabidopsis mutants glabra2 ( gl2 ) and immutans ( im ), which show altered epidermal plastid development, underscored their developmental plasticity. Our findings lay down the foundation for further investigations aimed at understanding the precise role and contributions of PCCs in plant interactions with the environment. © 2018. Published by The Company of Biologists Ltd.

  15. Pectin Biosynthesis Is Critical for Cell Wall Integrity and Immunity in Arabidopsis thaliana.

    Science.gov (United States)

    Bethke, Gerit; Thao, Amanda; Xiong, Guangyan; Li, Baohua; Soltis, Nicole E; Hatsugai, Noriyuki; Hillmer, Rachel A; Katagiri, Fumiaki; Kliebenstein, Daniel J; Pauly, Markus; Glazebrook, Jane

    2016-02-01

    Plant cell walls are important barriers against microbial pathogens. Cell walls of Arabidopsis thaliana leaves contain three major types of polysaccharides: cellulose, various hemicelluloses, and pectins. UDP-D-galacturonic acid, the key building block of pectins, is produced from the precursor UDP-D-glucuronic acid by the action of glucuronate 4-epimerases (GAEs). Pseudomonas syringae pv maculicola ES4326 (Pma ES4326) repressed expression of GAE1 and GAE6 in Arabidopsis, and immunity to Pma ES4326 was compromised in gae6 and gae1 gae6 mutant plants. These plants had brittle leaves and cell walls of leaves had less galacturonic acid. Resistance to specific Botrytis cinerea isolates was also compromised in gae1 gae6 double mutant plants. Although oligogalacturonide (OG)-induced immune signaling was unaltered in gae1 gae6 mutant plants, immune signaling induced by a commercial pectinase, macerozyme, was reduced. Macerozyme treatment or infection with B. cinerea released less soluble uronic acid, likely reflecting fewer OGs, from gae1 gae6 cell walls than from wild-type Col-0. Although both OGs and macerozyme-induced immunity to B. cinerea in Col-0, only OGs also induced immunity in gae1 gae6. Pectin is thus an important contributor to plant immunity, and this is due at least in part to the induction of immune responses by soluble pectin, likely OGs, that are released during plant-pathogen interactions. © 2016 American Society of Plant Biologists. All rights reserved.

  16. Gene expression analysis of WRKY transcription factors in Arabidopsis thaliana cell cultures during a parabolic flight

    Science.gov (United States)

    Babbick, Maren; Barjaktarović, Žarko; Hampp, Ruediger

    Plants sense gravity by specialized cells (statocytes) and adjust growth and development accordingly. It has, however, also been shown that plant cells which are not part of specialized tissues are also able to sense gravitational forces. Therefore we used undifferentiated, homogeneous cell cultures of Arabidopsis thaliana (cv. Columbia) in order to identify early alterations in gene expression as a response to altered gravitational field strengths. In this contribution we report on cell cultures exposed to parabolic flights (approximately 20 sec of microgravity). For this short-term exposure study, we specifically checked for genes at the beginning of signal transduction chains, such as those coding for transcription factors (TFs). TFs are small proteins that regulate expression of their target genes by binding to specific promoter sequences. Our main focus were members of the so-called WRKY TF family. WRKY TFs are known to be involved in various physiological processes like senescence and pathogen defense. By quantifying transcriptional changes of these genes by real-time RT-PCR, we wanted to find out, how gene expression is affected by both hyperand microgravity conditions during a parabolic flight. For this purpose Arabidopsis thaliana callus cultures were metabolically quenched by the injection of RNAlater at the end of the microgravity-phase of each parabola. The data we present will show how fast changes in amounts of transcripts will occur, and to what degree the expression profiles are comparable with data obtained from exposures to hypergravity and simulated microgravity.

  17. Molecular and Genetic Analysis of Hormone-Regulated Differential Cell Elongation in Arabidopsis

    Energy Technology Data Exchange (ETDEWEB)

    Ecker, Joseph R.

    2002-12-03

    The authors have utilized the response of Arabidopsis seedlings to the plant hormone ethylene to identify new genes involved in the regulation of ethylene biosynthesis, perception, signal transduction and differential cell growth. In building a genetic framework for the action of these genes, they developed a molecular model that has facilitated the understanding of the molecular requirements of ethylene for cell elongation processes. The ethylene response pathway in Arabidopsis appears to be primarily linear and is defined by the genes: ETR1, ETR2, ERS1, ERS2, EIN4, CTR1, EIN2, EIN3, EIN5 EIN6, and EIN. Downstream branches identified by the HLS1, EIR1, and AUX1 genes involve interactions with other hormonal (auxin) signals in the process of differential cell elongation in the hypocotyl hook. Cloning and characterization of HLS1 and three HLS1-LIKE genes in the laboratory has been supported under this award. HLS1 is required for differential elongation of cells in the hypocotyl and may act in the establishment of hormone gradients. Also during the award period, they have identified and begun preliminary characterization of two genes that genetically act upstream of the ethylene receptors. ETO1 and RAN1 encode negative regulators of ethylene biosynthesis and signaling respectively. Progress on the analysis of these genes along with HOOKLESS1 is described.

  18. Molecular and Genetic Analysis of Hormone-Regulated Differential Cell Elongation in Arabidopsis

    Energy Technology Data Exchange (ETDEWEB)

    Ecker, Joseph R.

    2005-09-15

    We have utilized the response of Arabidopsis seedlings to the plant hormone ethylene to identify new genes involved in the regulation of ethylene biosynthesis, perception, signal transduction and differential cell growth. In building a genetic framework for the action of these genes, we have developed a molecular model that has facilitated our understanding of the molecular requirements of ethylene for cell elongation processes. The ethylene response pathway in Arabidopsis appears to be primarily linear and is defined by the genes: ETR1, ETR2, ERS1, ERS2, EIN4, CTR1, EIN2, EIN3, EIN5, EIN6, and EIN. Downstream branches identified by the HLS1, EIR1, and AUX1 genes involve interactions with other hormonal (auxin) signals in the process of differential cell elongation in the hypocotyl hook. Cloning and characterization of HLS1 (and three HLL genes) and ETO1 (and ETOL genes) in my laboratory has been supported under this award. HLS1 is required for differential elongation of cells in the hypocotyl and may act in the establishment of hormone gradients. Also during the previous period, we have identified and characterized a gene that genetically acts upstream of the ethylene receptors. ETO1 encodes negative regulators of ethylene biosynthesis.

  19. A rapid chemical method for lysing Arabidopsis cells for protein analysis

    Directory of Open Access Journals (Sweden)

    Takano Tetsuo

    2011-07-01

    Full Text Available Abstract Background Protein extraction is a frequent procedure in biological research. For preparation of plant cell extracts, plant materials usually have to be ground and homogenized to physically break the robust cell wall, but this step is laborious and time-consuming when a large number of samples are handled at once. Results We developed a chemical method for lysing Arabidopsis cells without grinding. In this method, plants are boiled for just 10 minutes in a solution containing a Ca2+ chelator and detergent. Cell extracts prepared by this method were suitable for SDS-PAGE and immunoblot analysis. This method was also applicable to genomic DNA extraction for PCR analysis. Our method was applied to many other plant species, and worked well for some of them. Conclusions Our method is rapid and economical, and allows many samples to be prepared simultaneously for protein analysis. Our method is useful not only for Arabidopsis research but also research on certain other species.

  20. Expression of Arabidopsis Hexokinase in Citrus Guard Cells Controls Stomatal Aperture and Reduces Transpiration.

    Science.gov (United States)

    Lugassi, Nitsan; Kelly, Gilor; Fidel, Lena; Yaniv, Yossi; Attia, Ziv; Levi, Asher; Alchanatis, Victor; Moshelion, Menachem; Raveh, Eran; Carmi, Nir; Granot, David

    2015-01-01

    Hexokinase (HXK) is a sugar-phosphorylating enzyme involved in sugar-sensing. It has recently been shown that HXK in guard cells mediates stomatal closure and coordinates photosynthesis with transpiration in the annual species tomato and Arabidopsis. To examine the role of HXK in the control of the stomatal movement of perennial plants, we generated citrus plants that express Arabidopsis HXK1 (AtHXK1) under KST1, a guard cell-specific promoter. The expression of KST1 in the guard cells of citrus plants has been verified using GFP as a reporter gene. The expression of AtHXK1 in the guard cells of citrus reduced stomatal conductance and transpiration with no negative effect on the rate of photosynthesis, leading to increased water-use efficiency. The effects of light intensity and humidity on stomatal behavior were examined in rooted leaves of the citrus plants. The optimal intensity of photosynthetically active radiation and lower humidity enhanced stomatal closure of AtHXK1-expressing leaves, supporting the role of sugar in the regulation of citrus stomata. These results suggest that HXK coordinates photosynthesis and transpiration and stimulates stomatal closure not only in annual species, but also in perennial species.

  1. Isolation of a strong Arabidopsis guard cell promoter and its potential as a research tool

    Directory of Open Access Journals (Sweden)

    Siegel Robert S

    2008-02-01

    Full Text Available Abstract Background A common limitation in guard cell signaling research is that it is difficult to obtain consistent high expression of transgenes of interest in Arabidopsis guard cells using known guard cell promoters or the constitutive 35S cauliflower mosaic virus promoter. An additional drawback of the 35S promoter is that ectopically expressing a gene throughout the organism could cause pleiotropic effects. To improve available methods for targeted gene expression in guard cells, we isolated strong guard cell promoter candidates based on new guard cell-specific microarray analyses of 23,000 genes that are made available together with this report. Results A promoter, pGC1(At1g22690, drove strong and relatively specific reporter gene expression in guard cells including GUS (beta-glucuronidase and yellow cameleon YC3.60 (GFP-based calcium FRET reporter. Reporter gene expression was weaker in immature guard cells. The expression of YC3.60 was sufficiently strong to image intracellular Ca2+ dynamics in guard cells of intact plants and resolved spontaneous calcium transients in guard cells. The GC1 promoter also mediated strong reporter expression in clustered stomata in the stomatal development mutant too-many-mouths (tmm. Furthermore, the same promoter::reporter constructs also drove guard cell specific reporter expression in tobacco, illustrating the potential of this promoter as a method for high level expression in guard cells. A serial deletion of the promoter defined a guard cell expression promoter region. In addition, anti-sense repression using pGC1 was powerful for reducing specific GFP gene expression in guard cells while expression in leaf epidermal cells was not repressed, demonstrating strong cell-type preferential gene repression. Conclusion The pGC1 promoter described here drives strong reporter expression in guard cells of Arabidopsis and tobacco plants. It provides a potent research tool for targeted guard cell expression or

  2. Isolation of a strong Arabidopsis guard cell promoter and its potential as a research tool

    Science.gov (United States)

    Yang, Yingzhen; Costa, Alex; Leonhardt, Nathalie; Siegel, Robert S; Schroeder, Julian I

    2008-01-01

    Background A common limitation in guard cell signaling research is that it is difficult to obtain consistent high expression of transgenes of interest in Arabidopsis guard cells using known guard cell promoters or the constitutive 35S cauliflower mosaic virus promoter. An additional drawback of the 35S promoter is that ectopically expressing a gene throughout the organism could cause pleiotropic effects. To improve available methods for targeted gene expression in guard cells, we isolated strong guard cell promoter candidates based on new guard cell-specific microarray analyses of 23,000 genes that are made available together with this report. Results A promoter, pGC1(At1g22690), drove strong and relatively specific reporter gene expression in guard cells including GUS (beta-glucuronidase) and yellow cameleon YC3.60 (GFP-based calcium FRET reporter). Reporter gene expression was weaker in immature guard cells. The expression of YC3.60 was sufficiently strong to image intracellular Ca2+ dynamics in guard cells of intact plants and resolved spontaneous calcium transients in guard cells. The GC1 promoter also mediated strong reporter expression in clustered stomata in the stomatal development mutant too-many-mouths (tmm). Furthermore, the same promoter::reporter constructs also drove guard cell specific reporter expression in tobacco, illustrating the potential of this promoter as a method for high level expression in guard cells. A serial deletion of the promoter defined a guard cell expression promoter region. In addition, anti-sense repression using pGC1 was powerful for reducing specific GFP gene expression in guard cells while expression in leaf epidermal cells was not repressed, demonstrating strong cell-type preferential gene repression. Conclusion The pGC1 promoter described here drives strong reporter expression in guard cells of Arabidopsis and tobacco plants. It provides a potent research tool for targeted guard cell expression or gene silencing. It is also

  3. Vascular Cell Induction Culture System Using Arabidopsis Leaves (VISUAL) Reveals the Sequential Differentiation of Sieve Element-Like Cells.

    Science.gov (United States)

    Kondo, Yuki; Nurani, Alif Meem; Saito, Chieko; Ichihashi, Yasunori; Saito, Masato; Yamazaki, Kyoko; Mitsuda, Nobutaka; Ohme-Takagi, Masaru; Fukuda, Hiroo

    2016-06-01

    Cell differentiation is a complex process involving multiple steps, from initial cell fate specification to final differentiation. Procambial/cambial cells, which act as vascular stem cells, differentiate into both xylem and phloem cells during vascular development. Recent studies have identified regulatory cascades for xylem differentiation. However, the molecular mechanism underlying phloem differentiation is largely unexplored due to technical challenges. Here, we established an ectopic induction system for phloem differentiation named Vascular Cell Induction Culture System Using Arabidopsis Leaves (VISUAL). Our results verified similarities between VISUAL-induced Arabidopsis thaliana phloem cells and in vivo sieve elements. We performed network analysis using transcriptome data with VISUAL to dissect the processes underlying phloem differentiation, eventually identifying a factor involved in the regulation of the master transcription factor gene APL Thus, our culture system opens up new avenues not only for genetic studies of phloem differentiation, but also for future investigations of multidirectional differentiation from vascular stem cells. © 2016 American Society of Plant Biologists. All rights reserved.

  4. Investigation of roles for LRR-RLKs PNL1 and PNL2 in asymmetric cell division in Arabidopsis thaliana

    OpenAIRE

    Rodriguez, Maiti Celina

    2008-01-01

    Asymmetric cell division is a vital component of plant development. It enables cell differentiation and cell diversity. A key component of asymmetric cell division is cell signaling. Signals are believed to control polarization and orientation of asymmetric divisions during stomatal development. The findings of this report suggest that PNL1 and PNL2, two LRR-RLKs found in Arabidopsis and closely related to maize PAN1 LRR-RLK, are possibly involved in the signaling events occurring during the ...

  5. Lectin receptor kinases participate in protein-protein interactions to mediate plasma membrane-cell wall adhesions in Arabidopsis

    NARCIS (Netherlands)

    Gouget, A.; Senchou, V.; Govers, F.; Sanson, A.; Barre, A.; Rougé, P.; Pont-Lezica, R.; Canut, H.

    2006-01-01

    Interactions between plant cell walls and plasma membranes are essential for cells to function properly, but the molecules that mediate the structural continuity between wall and membrane are unknown. Some of these interactions, which are visualized upon tissue plasmolysis in Arabidopsis

  6. Different myrosinase and idioblast distribution in Arabidopsis and Brassica napus

    DEFF Research Database (Denmark)

    Andreasson, Erik; Jørgensen, Lise Bolt; Höglund, Anna-Stina

    2001-01-01

    Arabidopsis, Brassica napus, Myrosinase, Myrosinase Binding Protein, Glucosinolates, Myrosin Cell, Immunocytochemistry......Arabidopsis, Brassica napus, Myrosinase, Myrosinase Binding Protein, Glucosinolates, Myrosin Cell, Immunocytochemistry...

  7. SA and ROS are involved in methyl salicylate-induced programmed cell death in Arabidopsis thaliana.

    Science.gov (United States)

    Yun, Li Juan; Chen, Wen Li

    2011-07-01

    Programmed cell death (PCD) is a genetically encoded, active process that results in the death of individual cells, tissues, or whole organs, which plays an important role in the life cycles of plants and animals. Previous studies show that methyl salicylate (MeSA) is a defense signal molecular associated with systemic acquired resistance and hypersensitive reaction; however, whether MeSA can induce PCD in plant is still unknown. The morphological changes of Arabidopsis thaliana protoplasts exposed to MeSA were observed under fluorescence microscopy and transmission electron microscopy, and the induction of PCD was clearly distinguished by intense perinuclear chromatin margination, condensation of nuclear chromatin and DNA laddering after 3-h exposure of 100 μM MeSA. Our results also showed that salicylic acid (SA) was involved in MeSA-induced PCD by using a transgenic nahG Arabidopsis thaliana line, and the process was mediated by reactive oxygen species, which functioned with SA by making an amplification loop. Our study showed that MeSA could induce PCD in plant cell for the first time.

  8. Cell wall composition contributes to the control of transpiration efficiency in Arabidopsis thaliana.

    Science.gov (United States)

    Liang, Yun-Kuan; Xie, Xiaodong; Lindsay, Shona E; Wang, Yi Bing; Masle, Josette; Williamson, Lisa; Leyser, Ottoline; Hetherington, Alistair M

    2010-11-01

    To identify loci in Arabidopsis involved in the control of transpirational water loss and transpiration efficiency (TE) we carried out an infrared thermal imaging-based screen. We report the identification of a new allele of the Arabidopsis CesA7 cellulose synthase locus designated AtCesA7(irx3-5) involved in the control of TE. Leaves of the AtCesA7(irx3-5) mutant are warmer than the wild type (WT). This is due to reduced stomatal pore widths brought about by guard cells that are significantly smaller than the WT. The xylem of the AtCesA7(irx3-5) mutant is also partially collapsed, and we suggest that the small guard cells in the mutant result from decreased water supply to the developing leaf. We used carbon isotope discrimination to show that TE is increased in AtCesA7(irx3-5) when compared with the WT. Our work identifies a new class of genes that affects TE and raises the possibility that other genes involved in cell wall biosynthesis will have an impact on water use efficiency. © 2010 The Authors. The Plant Journal © 2010 Blackwell Publishing Ltd.

  9. Arabidopsis leucine-rich repeat extensin (LRX) proteins modify cell wall composition and influence plant growth.

    Science.gov (United States)

    Draeger, Christian; Ndinyanka Fabrice, Tohnyui; Gineau, Emilie; Mouille, Grégory; Kuhn, Benjamin M; Moller, Isabel; Abdou, Marie-Therese; Frey, Beat; Pauly, Markus; Bacic, Antony; Ringli, Christoph

    2015-06-24

    Leucine-rich repeat extensins (LRXs) are extracellular proteins consisting of an N-terminal leucine-rich repeat (LRR) domain and a C-terminal extensin domain containing the typical features of this class of structural hydroxyproline-rich glycoproteins (HRGPs). The LRR domain is likely to bind an interaction partner, whereas the extensin domain has an anchoring function to insolubilize the protein in the cell wall. Based on the analysis of the root hair-expressed LRX1 and LRX2 of Arabidopsis thaliana, LRX proteins are important for cell wall development. The importance of LRX proteins in non-root hair cells and on the structural changes induced by mutations in LRX genes remains elusive. The LRX gene family of Arabidopsis consists of eleven members, of which LRX3, LRX4, and LRX5 are expressed in aerial organs, such as leaves and stem. The importance of these LRX genes for plant development and particularly cell wall formation was investigated. Synergistic effects of mutations with gradually more severe growth retardation phenotypes in double and triple mutants suggest a similar function of the three genes. Analysis of cell wall composition revealed a number of changes to cell wall polysaccharides in the mutants. LRX3, LRX4, and LRX5, and most likely LRX proteins in general, are important for cell wall development. Due to the complexity of changes in cell wall structures in the lrx mutants, the exact function of LRX proteins remains to be determined. The increasingly strong growth-defect phenotypes in double and triple mutants suggests that the LRX proteins have similar functions and that they are important for proper plant development.

  10. The cell wall of Arabidopsis thaliana influences actin network dynamics.

    Science.gov (United States)

    Tolmie, Frances; Poulet, Axel; McKenna, Joseph; Sassmann, Stefan; Graumann, Katja; Deeks, Michael; Runions, John

    2017-07-20

    In plant cells, molecular connections link the cell wall-plasma membrane-actin cytoskeleton to form a continuum. It is hypothesized that the cell wall provides stable anchor points around which the actin cytoskeleton remodels. Here we use live cell imaging of fluorescently labelled marker proteins to quantify the organization and dynamics of the actin cytoskeleton and to determine the impact of disrupting connections within the continuum. Labelling of the actin cytoskeleton with green fluorescent protein (GFP)-fimbrin actin-binding domain 2 (FABD2) resulted in a network composed of fine filaments and thicker bundles that appeared as a highly dynamic remodelling meshwork. This differed substantially from the GFP-Lifeact-labelled network that appeared much more sparse with thick bundles that underwent 'simple movement', in which the bundles slightly change position, but in such a manner that the structure of the network was not substantially altered during the time of observation. Label-dependent differences in actin network morphology and remodelling necessitated development of two new image analysis techniques. The first of these, 'pairwise image subtraction', was applied to measurement of the more rapidly remodelling actin network labelled with GFP-FABD2, while the second, 'cumulative fluorescence intensity', was used to measure bulk remodelling of the actin cytoskeleton when labelled with GFP-Lifeact. In each case, these analysis techniques show that the actin cytoskeleton has a decreased rate of bulk remodelling when the cell wall-plasma membrane-actin continuum is disrupted either by plasmolysis or with isoxaben, a drug that specifically inhibits cellulose deposition. Changes in the rate of actin remodelling also affect its functionality, as observed by alteration in Golgi body motility. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  11. Analysis of chlorophyll fluorescence reveals stage specific patterns of chloroplast-containing cells during Arabidopsis embryogenesis

    Directory of Open Access Journals (Sweden)

    RICARDO I TEJOS

    2010-01-01

    Full Text Available The basic body plan of a plant is established early in embryogenesis when cells differentiate, giving rise to the apical and basal regions of the embryo. Using chlorophyll fluorescence as a marker for chloroplasts, we have detected specific patterns of chloroplast-containing cells at specific stages of embryogenesis. Non-randomly distributed chloroplast-containing cells are seen as early as the globular stage of embryogenesis in Arabidopsis. In the heart stage of embryogenesis, chloroplast containing cells are detected in epidermal cells as well as a central region of the heart stage embryo, forming a triangular septum of chloroplast-containing cells that divides the embryo into three equal sectors. Torpedo stage embryos have chloroplast-containing epidermal cells and a central band of chloroplast-containing cells in the cortex layer, just below the shoot apical meristem. In the walking-stick stage of embryogenesis, chloroplasts are present in the epidermal, cortex and endodermal cells. The chloroplasts appear reduced or absent from the provascular and columella cells of walking-stick stage embryos. These results suggest that there is a tight regulation of plastid differentiation during embryogenesis that generates specific patterns of chloroplast-containing cells in specific cell layers at specific stages of embryogenesis.

  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. Plant cells without detectable plastids are generated in the crumpled leaf mutant of Arabidopsis thaliana.

    Science.gov (United States)

    Chen, Yuling; Asano, Tomoya; Fujiwara, Makoto T; Yoshida, Shigeo; Machida, Yasunori; Yoshioka, Yasushi

    2009-05-01

    Plastids are maintained in cells by proliferating prior to cell division and being partitioned to each daughter cell during cell division. It is unclear, however, whether cells without plastids are generated when plastid division is suppressed. The crumpled leaf (crl) mutant of Arabidopsis thaliana is a plastid division mutant that displays severe abnormalities in plastid division and plant development. We show that the crl mutant contains cells lacking detectable plastids; this situation probably results from an unequal partitioning of plastids to each daughter cell. Our results suggest that crl has a partial defect in plastid expansion, which is suggested to be important in the partitioning of plastids to daughter cells when plastid division is suppressed. The absence of cells without detectable plastids in the accumulation and replication of chloroplasts 6 (arc6) mutant, another plastid division mutant of A. thaliana having no significant defects in plant morphology, suggests that the generation of cells without detectable plastids is one of the causes of the developmental abnormalities seen in crl plants. We also demonstrate that plastids with trace or undetectable amounts of chlorophyll are generated from enlarged plastids by a non-binary fission mode of plastid replication in both crl and arc6.

  14. Hydrogen Peroxide-induced Cell Death in Arabidopsis : Transcriptional and Mutant Analysis Reveals a Role of an Oxoglutarate-dependent Dioxygenase Gene in the Cell Death Process

    NARCIS (Netherlands)

    Gechev, Tsanko S.; Minkov, Ivan N.; Hille, Jacques

    2005-01-01

    Hydrogen peroxide is a major regulator of plant programmed cell death (PCD) but little is known about the downstream genes from the H2O2-signaling network that mediate the cell death. To address this question, a novel system for studying H2O2-induced programmed cell death in Arabidopsis thaliana was

  15. Differential growth of pavement cells of Arabidopsis thaliana leaf epidermis as revealed by microbead labeling.

    Science.gov (United States)

    Elsner, Joanna; Lipowczan, Marcin; Kwiatkowska, Dorota

    2018-02-01

    In numerous vascular plants, pavement cells of the leaf epidermis are shaped like a jigsaw-puzzle piece. Knowledge about the subcellular pattern of growth that accompanies morphogenesis of such a complex shape is crucial for studies of the role of the cytoskeleton, cell wall and phytohormones in plant cell development. Because the detailed growth pattern of the anticlinal and periclinal cell walls remains unknown, our aim was to measure pavement cell growth at a subcellular resolution. Using fluorescent microbeads applied to the surface of the adaxial leaf epidermis of Arabidopsis thaliana as landmarks for growth computation, we directly assessed the growth rates for the outer periclinal and anticlinal cell walls at a subcellular scale. We observed complementary tendencies in the growth pattern of the outer periclinal and anticlinal cell walls. Central portions of periclinal walls were characterized by relatively slow growth, while growth of the other wall portions was heterogeneous. Local growth of the periclinal walls accompanying lobe development after initiation was relatively fast and anisotropic, with maximal extension usually in the direction along the lobe axis. This growth pattern of the periclinal walls was complemented by the extension of the anticlinal walls, which was faster on the lobe sides than at the tips. Growth of the anticlinal and outer periclinal walls of leaf pavement cells is heterogeneous. The growth of the lobes resembles cell elongation via diffuse growth rather than tip growth. © 2018 Botanical Society of America.

  16. Restricted cell elongation in Arabidopsis hypocotyls is associated with a reduced average pectin esterification level

    Directory of Open Access Journals (Sweden)

    Derbyshire Paul

    2007-06-01

    Full Text Available Abstract Background Cell elongation is mainly limited by the extensibility of the cell wall. Dicotyledonous primary (growing cell walls contain cellulose, xyloglucan, pectin and proteins, but little is known about how each polymer class contributes to the cell wall mechanical properties that control extensibility. Results We present evidence that the degree of pectin methyl-esterification (DE% limits cell growth, and that a minimum level of about 60% DE is required for normal cell elongation in Arabidopsis hypocotyls. When the average DE% falls below this level, as in two gibberellic acid (GA mutants ga1-3 and gai, and plants expressing pectin methyl-esterase (PME1 from Aspergillus aculeatus, then hypocotyl elongation is reduced. Conclusion Low average levels of pectin DE% are associated with reduced cell elongation, implicating PMEs, the enzymes that regulate DE%, in the cell elongation process and in responses to GA. At high average DE% other components of the cell wall limit GA-induced growth.

  17. Proteomic characterization of golgi membranes enriched from Arabidopsis suspension cell cultures

    DEFF Research Database (Denmark)

    Hansen, Sara Fasmer; Ebert, Berit; Rautengarten, Carsten

    2016-01-01

    The plant Golgi apparatus has a central role in the secretory pathway and is the principal site within the cell for the assembly and processing of macromolecules. The stacked membrane structure of the Golgi apparatus along with its interactions with the cytoskeleton and endoplasmic reticulum has...... historically made the isolation and purification of this organelle difficult. Density centrifugation has typically been used to enrich Golgi membranes from plant microsomal preparations, and aside from minor adaptations, the approach is still widely employed. Here we outline the enrichment of Golgi membranes...... from an Arabidopsis cell suspension culture that can be used to investigate the proteome of this organelle. We also provide a useful workflow for the examination of proteomic data as the result of multiple analyses. Finally, we highlight a simple technique to validate the subcellular localization...

  18. Enhanced Toxic Metal Accumulation in Engineered Bacterial Cells Expressing Arabidopsis thaliana Phytochelatin Synthase

    Science.gov (United States)

    Sauge-Merle, Sandrine; Cuiné, Stéphan; Carrier, Patrick; Lecomte-Pradines, Catherine; Luu, Doan-Trung; Peltier, Gilles

    2003-01-01

    Phytochelatins (PCs) are metal-binding cysteine-rich peptides, enzymatically synthesized in plants and yeasts from glutathione in response to heavy metal stress by PC synthase (EC 2.3.2.15). In an attempt to increase the ability of bacterial cells to accumulate heavy metals, the Arabidopsis thaliana gene encoding PC synthase (AtPCS) was expressed in Escherichia coli. A marked accumulation of PCs was observed in vivo together with a decrease in the glutathione cellular content. When bacterial cells expressing AtPCS were placed in the presence of heavy metals such as cadmium or the metalloid arsenic, cellular metal contents were increased 20- and 50-fold, respectively. We discuss the possibility of using genes of the PC biosynthetic pathway to design bacterial strains or higher plants with increased abilities to accumulate toxic metals, and also arsenic, for use in bioremediation and/or phytoremediation processes. PMID:12514032

  19. Quantitative proteome changes in Arabidopsis thaliana suspension-cultured cells in response to plant natriuretic peptides

    KAUST Repository

    Turek, Ilona; Wheeler, Janet I.; Gehring, Christoph A; Irving, Helen R.; Marondedze, Claudius

    2015-01-01

    Proteome changes in the Arabidopsis thaliana suspension cells in response to the A. thaliana plant natriuretic peptide (PNP), AtPNP-A (At2g18660) were assessed using quantitative proteomics employing tandem mass tag (TMT) labeling and tandem mass spectrometry (LC–MS/MS). In this study, we characterized temporal responses of suspension-cultured cells to 1 nM and 10 pM AtPNP-A at 0, 10 and 30 min post-treatment. Both concentrations we found to yield a distinct differential proteome signature. The data shown in this article are associated with the article “Plant natriuretic peptides induce a specific set of proteins diagnostic for an adaptive response to abiotic stress” by Turek et al. (Front. Plant Sci. 5 (2014) 661) and have been deposited to the ProteomeXchange with identifier PXD001386.

  20. Quantitative proteome changes in Arabidopsis thaliana suspension-cultured cells in response to plant natriuretic peptides

    KAUST Repository

    Turek, Ilona

    2015-06-30

    Proteome changes in the Arabidopsis thaliana suspension cells in response to the A. thaliana plant natriuretic peptide (PNP), AtPNP-A (At2g18660) were assessed using quantitative proteomics employing tandem mass tag (TMT) labeling and tandem mass spectrometry (LC–MS/MS). In this study, we characterized temporal responses of suspension-cultured cells to 1 nM and 10 pM AtPNP-A at 0, 10 and 30 min post-treatment. Both concentrations we found to yield a distinct differential proteome signature. The data shown in this article are associated with the article “Plant natriuretic peptides induce a specific set of proteins diagnostic for an adaptive response to abiotic stress” by Turek et al. (Front. Plant Sci. 5 (2014) 661) and have been deposited to the ProteomeXchange with identifier PXD001386.

  1. Arabidopsis phyllotaxis is controlled by the methyl-esterification status of cell-wall pectins.

    Science.gov (United States)

    Peaucelle, Alexis; Louvet, Romain; Johansen, Jorunn N; Höfte, Herman; Laufs, Patrick; Pelloux, Jérome; Mouille, Grégory

    2008-12-23

    Plant organs are produced from meristems in a characteristic pattern. This pattern, referred to as phyllotaxis, is thought to be generated by local gradients of an information molecule, auxin. Some studies propose a key role for the mechanical properties of the cell walls in the control of organ outgrowth. A major cell-wall component is the linear alpha-1-4-linked D-GalAp pectic polysaccharide homogalacturonan (HG), which plays a key role in cell-to-cell cohesion. HG is deposited in the cell wall in a highly (70%-80%) methyl-esterified form and is subsequently de-methyl-esterified by pectin methyl-esterases (PME, EC 3.1.1.11). PME activity is itself regulated by endogenous PME inhibitor (PMEI) proteins. PME action modulates cell-wall-matrix properties and plays a role in the control of cell growth. Here, we show that the formation of flower primordia in the Arabidopsis shoot apical meristem is accompanied by the de-methyl-esterification of pectic polysaccharides in the cell walls. In addition, experimental perturbation of the methyl-esterification status of pectins within the meristem dramatically alters the phyllotactic pattern. These results demonstrate that regulated de-methyl-esterification of pectins is a key event in the outgrowth of primordia and possibly also in phyllotactic patterning.

  2. Arabidopsis R-SNARE proteins VAMP721 and VAMP722 are required for cell plate formation.

    Directory of Open Access Journals (Sweden)

    Liang Zhang

    Full Text Available BACKGROUND: Cell plate formation during plant cytokinesis is facilitated by SNARE complex-mediated vesicle fusion at the cell-division plane. However, our knowledge regarding R-SNARE components of membrane fusion machinery for cell plate formation remains quite limited. METHODOLOGY/PRINCIPAL FINDINGS: We report the in vivo function of Arabidopsis VAMP721 and VAMP722, two closely sequence-related R-SNAREs, in cell plate formation. Double homozygous vamp721vamp722 mutant seedlings showed lethal dwarf phenotypes and were characterized by rudimentary roots, cotyledons and hypocotyls. Furthermore, cell wall stubs and incomplete cytokinesis were frequently observed in vamp721vamp722 seedlings. Confocal images revealed that green fluorescent protein-tagged VAMP721 and VAMP722 were preferentially localized to the expanding cell plates in dividing cells. Drug treatments and co-localization analyses demonstrated that punctuate organelles labeled with VAMP721 and VAMP722 represented early endosomes overlapped with VHA-a1-labeled TGN, which were distinct from Golgi stacks and prevacuolar compartments. In addition, protein traffic to the plasma membrane, but not to the vacuole, was severely disrupted in vamp721vamp722 seedlings by subcellular localization of marker proteins. CONCLUSION/SIGNIFICANCE: These observations suggest that VAMP721 and VAMP722 are involved in secretory trafficking to the plasma membrane via TGN/early endosomal compartment, which contributes substantially to cell plate formation during plant cytokinesis.

  3. Arabidopsis FH1 Formin Affects Cotyledon Pavement Cell Shape by Modulating Cytoskeleton Dynamics.

    Science.gov (United States)

    Rosero, Amparo; Oulehlová, Denisa; Stillerová, Lenka; Schiebertová, Petra; Grunt, Michal; Žárský, Viktor; Cvrčková, Fatima

    2016-03-01

    Plant cell morphogenesis involves concerted rearrangements of microtubules and actin microfilaments. We previously reported that FH1, the main Arabidopsis thaliana housekeeping Class I membrane-anchored formin, contributes to actin dynamics and microtubule stability in rhizodermis cells. Here we examine the effects of mutations affecting FH1 (At3g25500) on cell morphogenesis and above-ground organ development in seedlings, as well as on cytoskeletal organization and dynamics, using a combination of confocal and variable angle epifluorescence microscopy with a pharmacological approach. Homozygous fh1 mutants exhibited cotyledon epinasty and had larger cotyledon pavement cells with more pronounced lobes than the wild type. The pavement cell shape alterations were enhanced by expression of the fluorescent microtubule marker GFP-microtubule-associated protein 4 (MAP4). Mutant cotyledon pavement cells exhibited reduced density and increased stability of microfilament bundles, as well as enhanced dynamics of microtubules. Analogous results were also obtained upon treatments with the formin inhibitor SMIFH2 (small molecule inhibitor of formin homology 2 domains). Pavement cell shape in wild-type (wt) and fh1 plants in some situations exhibited a differential response towards anti-cytoskeletal drugs, especially the microtubule disruptor oryzalin. Our observations indicate that FH1 participates in the control of microtubule dynamics, possibly via its effects on actin, subsequently influencing cell morphogenesis and macroscopic organ development. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  4. A pharmacological study of Arabidopsis cell fusion between the persistent synergid and endosperm.

    Science.gov (United States)

    Motomura, Kazuki; Kawashima, Tomokazu; Berger, Frédéric; Kinoshita, Tetsu; Higashiyama, Tetsuya; Maruyama, Daisuke

    2018-01-29

    Cell fusion is a pivotal process in fertilization and multinucleate cell formation. A plant cell is ubiquitously surrounded by a hard cell wall, and very few cell fusions have been observed except for gamete fusions. We recently reported that the fertilized central cell (the endosperm) absorbs the persistent synergid, a highly differentiated cell necessary for pollen tube attraction. The synergid-endosperm fusion (SE fusion) appears to eliminate the persistent synergid from fertilized ovule in Arabidopsis thaliana Here, we analyzed the effects of various inhibitors on SE fusion in an in vitro culture system. Different from other cell fusions, neither disruption of actin polymerization nor protein secretion impaired SE fusion. However, transcriptional and translational inhibitors decreased the SE fusion success rate and also inhibited endosperm division. Failures of SE fusion and endosperm nuclear proliferation were also induced by roscovitine, an inhibitor of cyclin-dependent kinases (CDK). These data indicate unique aspects of SE fusion such as independence of filamentous actin support and the importance of CDK-mediated mitotic control. © 2018. Published by The Company of Biologists Ltd.

  5. Lignin monomer composition affects Arabidopsis cell-wall degradability after liquid hot water pretreatment

    Directory of Open Access Journals (Sweden)

    Ladisch Michael

    2010-12-01

    Full Text Available Abstract Background Lignin is embedded in the plant cell wall matrix, and impedes the enzymatic saccharification of lignocellulosic feedstocks. To investigate whether enzymatic digestibility of cell wall materials can be improved by altering the relative abundance of the two major lignin monomers, guaiacyl (G and syringyl (S subunits, we compared the degradability of cell wall material from wild-type Arabidopsis thaliana with a mutant line and a genetically modified line, the lignins of which are enriched in G and S subunits, respectively. Results Arabidopsis tissue containing G- and S-rich lignins had the same saccharification performance as the wild type when subjected to enzyme hydrolysis without pretreatment. After a 24-hour incubation period, less than 30% of the total glucan was hydrolyzed. By contrast, when liquid hot water (LHW pretreatment was included before enzyme hydrolysis, the S-lignin-rich tissue gave a much higher glucose yield than either the wild-type or G-lignin-rich tissue. Applying a hot-water washing step after the pretreatment did not lead to a further increase in final glucose yield, but the initial hydrolytic rate was doubled. Conclusions Our analyses using the model plant A. thaliana revealed that lignin composition affects the enzymatic digestibility of LHW pretreated plant material. Pretreatment is more effective in enhancing the saccharification of A. thaliana cell walls that contain S-rich lignin. Increasing lignin S monomer content through genetic engineering may be a promising approach to increase the efficiency and reduce the cost of biomass to biofuel conversion.

  6. Subcellular and supracellular mechanical stress prescribes cytoskeleton behavior in Arabidopsis cotyledon pavement cells

    Science.gov (United States)

    Sampathkumar, Arun; Krupinski, Pawel; Wightman, Raymond; Milani, Pascale; Berquand, Alexandre; Boudaoud, Arezki; Hamant, Olivier; Jönsson, Henrik; Meyerowitz, Elliot M

    2014-01-01

    Although it is a central question in biology, how cell shape controls intracellular dynamics largely remains an open question. Here, we show that the shape of Arabidopsis pavement cells creates a stress pattern that controls microtubule orientation, which then guides cell wall reinforcement. Live-imaging, combined with modeling of cell mechanics, shows that microtubules align along the maximal tensile stress direction within the cells, and atomic force microscopy demonstrates that this leads to reinforcement of the cell wall parallel to the microtubules. This feedback loop is regulated: cell-shape derived stresses could be overridden by imposed tissue level stresses, showing how competition between subcellular and supracellular cues control microtubule behavior. Furthermore, at the microtubule level, we identified an amplification mechanism in which mechanical stress promotes the microtubule response to stress by increasing severing activity. These multiscale feedbacks likely contribute to the robustness of microtubule behavior in plant epidermis. DOI: http://dx.doi.org/10.7554/eLife.01967.001 PMID:24740969

  7. Variable-angle total internal reflection fluorescence microscopy of intact cells of Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Kim Myung K

    2011-09-01

    Full Text Available Abstract Background Total internal reflection fluorescence microscopy (TIRFM is a powerful tool for observing fluorescently labeled molecules on the plasma membrane surface of animal cells. However, the utility of TIRFM in plant cell studies has been limited by the fact that plants have cell walls, thick peripheral layers surrounding the plasma membrane. Recently, a new technique known as variable-angle epifluorescence microscopy (VAEM was developed to circumvent this problem. However, the lack of a detailed analysis of the optical principles underlying VAEM has limited its applications in plant-cell biology. Results Here, we present theoretical and experimental evidence supporting the use of variable-angle TIRFM in observations of intact plant cells. We show that when total internal reflection occurs at the cell wall/cytosol interface with an appropriate angle of incidence, an evanescent wave field of constant depth is produced inside the cytosol. Results of experimental TIRFM observations of the dynamic behaviors of phototropin 1 (a membrane receptor protein and clathrin light chain (a vesicle coat protein support our theoretical analysis. Conclusions These findings demonstrate that variable-angle TIRFM is appropriate for quantitative live imaging of cells in intact tissues of Arabidopsis thaliana.

  8. Atkinesin-13A Modulates Cell-Wall Synthesis and Cell Expansion in Arabidopsis thaliana via the THESEUS1 Pathway

    Science.gov (United States)

    Fujikura, Ushio; Elsaesser, Lore; Breuninger, Holger; Sánchez-Rodríguez, Clara; Ivakov, Alexander; Laux, Thomas; Findlay, Kim; Persson, Staffan; Lenhard, Michael

    2014-01-01

    Growth of plant organs relies on cell proliferation and expansion. While an increasingly detailed picture about the control of cell proliferation is emerging, our knowledge about the control of cell expansion remains more limited. We demonstrate here that the internal-motor kinesin AtKINESIN-13A (AtKIN13A) limits cell expansion and cell size in Arabidopsis thaliana, with loss-of-function atkin13a mutants forming larger petals with larger cells. The homolog, AtKINESIN-13B, also affects cell expansion and double mutants display growth, gametophytic and early embryonic defects, indicating a redundant role of the two genes. AtKIN13A is known to depolymerize microtubules and influence Golgi motility and distribution. Consistent with this function, AtKIN13A interacts genetically with ANGUSTIFOLIA, encoding a regulator of Golgi dynamics. Reduced AtKIN13A activity alters cell wall structure as assessed by Fourier-transformed infrared-spectroscopy and triggers signalling via the THESEUS1-dependent cell-wall integrity pathway, which in turn promotes the excess cell expansion in the atkin13a mutant. Thus, our results indicate that the intracellular activity of AtKIN13A regulates cell expansion and wall architecture via THESEUS1, providing a compelling case of interplay between cell wall integrity sensing and expansion. PMID:25232944

  9. Ascorbic acid deficiency activates cell death and disease resistance responses in Arabidopsis.

    Science.gov (United States)

    Pavet, Valeria; Olmos, Enrique; Kiddle, Guy; Mowla, Shaheen; Kumar, Sanjay; Antoniw, John; Alvarez, María E; Foyer, Christine H

    2005-11-01

    Programmed cell death, developmental senescence, and responses to pathogens are linked through complex genetic controls that are influenced by redox regulation. Here we show that the Arabidopsis (Arabidopsis thaliana) low vitamin C mutants, vtc1 and vtc2, which have between 10% and 25% of wild-type ascorbic acid, exhibit microlesions, express pathogenesis-related (PR) proteins, and have enhanced basal resistance against infections caused by Pseudomonas syringae. The mutants have a delayed senescence phenotype with smaller leaf cells than the wild type at maturity. The vtc leaves have more glutathione than the wild type, with higher ratios of reduced glutathione to glutathione disulfide. Expression of green fluorescence protein (GFP) fused to the nonexpressor of PR protein 1 (GFP-NPR1) was used to detect the presence of NPR1 in the nuclei of transformed plants. Fluorescence was observed in the nuclei of 6- to 8-week-old GFP-NPR1 vtc1 plants, but not in the nuclei of transformed GFP-NPR1 wild-type plants at any developmental stage. The absence of senescence-associated gene 12 (SAG12) mRNA at the time when constitutive cell death and basal resistance were detected confirms that elaboration of innate immune responses in vtc plants does not result from activation of early senescence. Moreover, H2O2-sensitive genes are not induced at the time of systemic acquired resistance execution. These results demonstrate that ascorbic acid abundance modifies the threshold for activation of plant innate defense responses via redox mechanisms that are independent of the natural senescence program.

  10. An extensive microarray analysis of AAL-toxin-induced cell death in Arabidopsis thaliana brings new insights into the complexity of programmed cell death in plants

    NARCIS (Netherlands)

    Gechev, T.S.; Gadjev, I.Z.; Hille, J.

    2004-01-01

    A T-DNA knockout of the Arabidopsis homologue of the tomato disease resistance gene Asc was obtained. The asc gene renders plants sensitive to programmed cell death (PCD) triggered by the fungal AAL toxin. To obtain more insights into the nature of AAL-toxin-induced cell death and to identify genes

  11. Effect of amino acid substitution of CAPRICE on cell-to-cell movement ability in Arabidopsis root epidermis.

    Science.gov (United States)

    Tominaga-Wada, Rumi; Wada, Takuji

    2018-03-01

    An R3-type MYB transcription factor, CAPRICE (CPC), is known to promote root hair cell differentiation in Arabidopsis root epidermis. The CPC protein moves from non-hair cells to the neighboring cells, and acts as an inducer of root hair formation. In contrast, we previously showed that the CPC homolog, ENHANCER OF TRY AND CPC1 (ETC1), does not move between the root epidermal cells. To clarify the critical difference in the cell-to-cell movement ability of CPC and ETC1 proteins, we generated five different chimeras of CPC and ETC1. As expected, four of the five chimeric proteins with substitution of CPC amino acids with those of ETC1 induced many root hair and no-trichome phenotype, like CPC. These chimeric proteins essentially maintained the cell-to-cell movement ability of CPC. However, one chimeric protein in which ETC1 was sandwiched between the CPC-specific movement motifs of S1 and S2 did not induce ectopic root hair formation. This chimeric protein did not move between the cells. These results indicate that the maintenance of not only the S1 and S2 motifs but also the precise structure of CPC protein might be necessary for the cell-to-cell movement of CPC. Our results should help in further unraveling of the roles of these MYB transcription factors in root hair formation. Copyright © 2018 Elsevier Inc. All rights reserved.

  12. Dynamics of vegetative cytoplasm during generative cell formation and pollen maturation in Arabidopsis thaliana

    Science.gov (United States)

    Kuang, A.; Musgrave, M. E.

    1996-01-01

    Ultrastructural changes of pollen cytoplasm during generative cell formation and pollen maturation in Arabidopsis thaliana were studied. The pollen cytoplasm develops a complicated ultrastructure and changes dramatically during these stages. Lipid droplets increase after generative cell formation and their organization and distribution change with the developmental stage. Starch grains in amyloplasts increase in number and size during generative and sperm cell formation and decrease at pollen maturity. The shape and membrane system of mitochondria change only slightly. Dictyosomes become very prominent, and numerous associated vesicles are observed during and after sperm cell formation. Endoplasmic reticulum appears extensively as stacks during sperm cell formation. Free and polyribosomes are abundant in the cytoplasm at all developmental stages although they appear denser at certain stages and in some areas. In mature pollen, all organelles are randomly distributed throughout the vegetative cytoplasm and numerous small particles appear. Organization and distribution of storage substances and appearance of these small particles during generative and sperm cell formation and pollen maturation are discussed.

  13. The Arabidopsis Transcription Factor AtTCP15 Regulates Endoreduplication by Modulating Expression of Key Cell-cycle Genes

    Institute of Scientific and Technical Information of China (English)

    Zi-Yu Li; Bin Li; Ai-Wu Dong

    2012-01-01

    Plant cells frequently undergo endoreduplication,a modified cell cycle in which genome is repeatedly replicated without cytokinesis.As the key step to achieve final size and function for cells,endoreduplication is prevalent during plant development.However,mechanisms to control the balance between endoreduplication and mitotic cell division are still poorly understood.Here,we show that the Arabidopsis TCP (CINCINNATA-like TEOSINTE BRANCHED1-CYCLOIDEA-PCF)-family transcription factor gene AtTCP15 is expressed in trichomes,as well as in rapidly dividing and vascular tissues.Expression of AtTCP15SRDX,AtTCP15 fused with a SRDX repressor domain,induces extra endoreduplication in trichomes and cotyledon cells in transgenic Arabidopsis.On the contrary,overexpression of AtTCP15 suppresses endoreduplication in trichomes and other examined cells.Misregulation of AtTCP15 affects the expression of several important genes involved in cell-cycle regulation.AtTCP15 protein binds directly to the promoter regions of CYCA2;3 and RETINOBLASTOMA-RELATED (RBR) genes,which play key roles in endoreduplication.Taken together,AtTCP15 plays an important role in regulating endoreduplication during Arabidopsis development.

  14. Single-cell telomere-length quantification couples telomere length to meristem activity and stem cell development in Arabidopsis.

    Science.gov (United States)

    González-García, Mary-Paz; Pavelescu, Irina; Canela, Andrés; Sevillano, Xavier; Leehy, Katherine A; Nelson, Andrew D L; Ibañes, Marta; Shippen, Dorothy E; Blasco, Maria A; Caño-Delgado, Ana I

    2015-05-12

    Telomeres are specialized nucleoprotein caps that protect chromosome ends assuring cell division. Single-cell telomere quantification in animals established a critical role for telomerase in stem cells, yet, in plants, telomere-length quantification has been reported only at the organ level. Here, a quantitative analysis of telomere length of single cells in Arabidopsis root apex uncovered a heterogeneous telomere-length distribution of different cell lineages showing the longest telomeres at the stem cells. The defects in meristem and stem cell renewal observed in tert mutants demonstrate that telomere lengthening by TERT sets a replicative limit in the root meristem. Conversely, the long telomeres of the columella cells and the premature stem cell differentiation plt1,2 mutants suggest that differentiation can prevent telomere erosion. Overall, our results indicate that telomere dynamics are coupled to meristem activity and continuous growth, disclosing a critical association between telomere length, stem cell function, and the extended lifespan of plants. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  15. METACASPASE9 modulates autophagy to confine cell death to the target cells during Arabidopsis vascular xylem differentiation

    Directory of Open Access Journals (Sweden)

    Sacha Escamez

    2016-02-01

    Full Text Available We uncovered that the level of autophagy in plant cells undergoing programmed cell death determines the fate of the surrounding cells. Our approach consisted of using Arabidopsis thaliana cell cultures capable of differentiating into two different cell types: vascular tracheary elements (TEs that undergo programmed cell death (PCD and protoplast autolysis, and parenchymatic non-TEs that remain alive. The TE cell type displayed higher levels of autophagy when expression of the TE-specific METACASPASE9 (MC9 was reduced using RNAi (MC9-RNAi. Misregulation of autophagy in the MC9-RNAi TEs coincided with ectopic death of the non-TEs, implying the existence of an autophagy-dependent intercellular signalling from within the TEs towards the non-TEs. Viability of the non-TEs was restored when AUTOPHAGY2 (ATG2 was downregulated specifically in MC9-RNAi TEs, demonstrating the importance of autophagy in the spatial confinement of cell death. Our results suggest that other eukaryotic cells undergoing PCD might also need to tightly regulate their level of autophagy to avoid detrimental consequences for the surrounding cells.

  16. Identification of the arabidopsis RAM/MOR signalling network: adding new regulatory players in plant stem cell maintenance and cell polarization

    Science.gov (United States)

    Zermiani, Monica; Begheldo, Maura; Nonis, Alessandro; Palme, Klaus; Mizzi, Luca; Morandini, Piero; Nonis, Alberto; Ruperti, Benedetto

    2015-01-01

    Background and Aims The RAM/MOR signalling network of eukaryotes is a conserved regulatory module involved in co-ordination of stem cell maintenance, cell differentiation and polarity establishment. To date, no such signalling network has been identified in plants. Methods Genes encoding the bona fide core components of the RAM/MOR pathway were identified in Arabidopsis thaliana (arabidopsis) by sequence similarity searches conducted with the known components from other species. The transcriptional network(s) of the arabidopsis RAM/MOR signalling pathway were identified by running in-depth in silico analyses for genes co-regulated with the core components. In situ hybridization was used to confirm tissue-specific expression of selected RAM/MOR genes. Key Results Co-expression data suggested that the arabidopsis RAM/MOR pathway may include genes involved in floral transition, by co-operating with chromatin remodelling and mRNA processing/post-transcriptional gene silencing factors, and genes involved in the regulation of pollen tube polar growth. The RAM/MOR pathway may act upstream of the ROP1 machinery, affecting pollen tube polar growth, based on the co-expression of its components with ROP-GEFs. In silico tissue-specific co-expression data and in situ hybridization experiments suggest that different components of the arabidopsis RAM/MOR are expressed in the shoot apical meristem and inflorescence meristem and may be involved in the fine-tuning of stem cell maintenance and cell differentiation. Conclusions The arabidopsis RAM/MOR pathway may be part of the signalling cascade that converges in pollen tube polarized growth and in fine-tuning stem cell maintenance, differentiation and organ polarity. PMID:26078466

  17. Glycosylphosphatidylinositol-anchored proteins are required for cell wall synthesis and morphogenesis in Arabidopsis.

    Science.gov (United States)

    Gillmor, C Stewart; Lukowitz, Wolfgang; Brininstool, Ginger; Sedbrook, John C; Hamann, Thorsten; Poindexter, Patricia; Somerville, Chris

    2005-04-01

    Mutations at five loci named PEANUT1-5 (PNT) were identified in a genetic screen for radially swollen embryo mutants. pnt1 cell walls showed decreased crystalline cellulose, increased pectins, and irregular and ectopic deposition of pectins, xyloglucans, and callose. Furthermore, pnt1 pollen is less viable than the wild type, and pnt1 embryos were delayed in morphogenesis and showed defects in shoot and root meristems. The PNT1 gene encodes the Arabidopsis thaliana homolog of mammalian PIG-M, an endoplasmic reticulum-localized mannosyltransferase that is required for synthesis of the glycosylphosphatidylinositol (GPI) anchor. All five pnt mutants showed strongly reduced accumulation of GPI-anchored proteins, suggesting that they all have defects in GPI anchor synthesis. Although the mutants are seedling lethal, pnt1 cells are able to proliferate for a limited time as undifferentiated callus and do not show the massive deposition of ectopic cell wall material seen in pnt1 embryos. The different phenotype of pnt1 cells in embryos and callus suggest a differential requirement for GPI-anchored proteins in cell wall synthesis in these two tissues and points to the importance of GPI anchoring in coordinated multicellular growth.

  18. Fluctuations of the transcription factor ATML1 generate the pattern of giant cells in the Arabidopsis sepal

    Science.gov (United States)

    Meyer, Heather M; Teles, José; Formosa-Jordan, Pau; Refahi, Yassin; San-Bento, Rita; Ingram, Gwyneth; Jönsson, Henrik; Locke, James C W; Roeder, Adrienne H K

    2017-01-01

    Multicellular development produces patterns of specialized cell types. Yet, it is often unclear how individual cells within a field of identical cells initiate the patterning process. Using live imaging, quantitative image analyses and modeling, we show that during Arabidopsis thaliana sepal development, fluctuations in the concentration of the transcription factor ATML1 pattern a field of identical epidermal cells to differentiate into giant cells interspersed between smaller cells. We find that ATML1 is expressed in all epidermal cells. However, its level fluctuates in each of these cells. If ATML1 levels surpass a threshold during the G2 phase of the cell cycle, the cell will likely enter a state of endoreduplication and become giant. Otherwise, the cell divides. Our results demonstrate a fluctuation-driven patterning mechanism for how cell fate decisions can be initiated through a random yet tightly regulated process. DOI: http://dx.doi.org/10.7554/eLife.19131.001 PMID:28145865

  19. Differential Growth in Periclinal and Anticlinal Walls during Lobe Formation in Arabidopsis Cotyledon Pavement Cells.

    Science.gov (United States)

    Armour, William J; Barton, Deborah A; Law, Andrew M K; Overall, Robyn L

    2015-09-01

    Lobe development in the epidermal pavement cells of Arabidopsis thaliana cotyledons and leaves is thought to take place via tip-like growth on the concave side of lobes driven by localized concentrations of actin filaments and associated proteins, with a predicted role for cortical microtubules in establishing the direction of restricted growth at the convex side. We used homologous landmarks fixed to the outer walls of pavement cells and thin-plate spline analysis to demonstrate that lobes form by differential growth of both the anticlinal and periclinal walls. Most lobes formed within the first 24 h of the cotyledons unfurling, during the period of rapid cell expansion. Cortical microtubules adjacent to the periclinal wall were persistently enriched at the convex side of lobes during development where growth was anisotropic and were less concentrated or absent at the concave side where growth was promoted. Alternating microtubule-enriched and microtubule-free zones at the periclinal wall in neighboring cells predicted sites of new lobes. There was no particular arrangement of cortical actin filaments that could predict where lobes would form. However, drug studies demonstrate that both filamentous actin and microtubules are required for lobe formation. © 2015 American Society of Plant Biologists. All rights reserved.

  20. Differential Growth in Periclinal and Anticlinal Walls during Lobe Formation in Arabidopsis Cotyledon Pavement Cells

    Science.gov (United States)

    Barton, Deborah A.; Law, Andrew M.K.; Overall, Robyn L.

    2015-01-01

    Lobe development in the epidermal pavement cells of Arabidopsis thaliana cotyledons and leaves is thought to take place via tip-like growth on the concave side of lobes driven by localized concentrations of actin filaments and associated proteins, with a predicted role for cortical microtubules in establishing the direction of restricted growth at the convex side. We used homologous landmarks fixed to the outer walls of pavement cells and thin-plate spline analysis to demonstrate that lobes form by differential growth of both the anticlinal and periclinal walls. Most lobes formed within the first 24 h of the cotyledons unfurling, during the period of rapid cell expansion. Cortical microtubules adjacent to the periclinal wall were persistently enriched at the convex side of lobes during development where growth was anisotropic and were less concentrated or absent at the concave side where growth was promoted. Alternating microtubule-enriched and microtubule-free zones at the periclinal wall in neighboring cells predicted sites of new lobes. There was no particular arrangement of cortical actin filaments that could predict where lobes would form. However, drug studies demonstrate that both filamentous actin and microtubules are required for lobe formation. PMID:26296967

  1. POLYGALACTURONASE INVOLVED IN EXPANSION1 functions in cell elongation and flower development in Arabidopsis.

    Science.gov (United States)

    Xiao, Chaowen; Somerville, Chris; Anderson, Charles T

    2014-03-01

    Pectins are acidic carbohydrates that comprise a significant fraction of the primary walls of eudicotyledonous plant cells. They influence wall porosity and extensibility, thus controlling cell and organ growth during plant development. The regulated degradation of pectins is required for many cell separation events in plants, but the role of pectin degradation in cell expansion is poorly defined. Using an activation tag screen designed to isolate genes involved in wall expansion, we identified a gene encoding a putative polygalacturonase that, when overexpressed, resulted in enhanced hypocotyl elongation in etiolated Arabidopsis thaliana seedlings. We named this gene POLYGALACTURONASE INVOLVED IN EXPANSION1 (PGX1). Plants lacking PGX1 display reduced hypocotyl elongation that is complemented by transgenic PGX1 expression. PGX1 is expressed in expanding tissues throughout development, including seedlings, roots, leaves, and flowers. PGX1-GFP (green fluorescent protein) localizes to the apoplast, and heterologously expressed PGX1 displays in vitro polygalacturonase activity, supporting a function for this protein in apoplastic pectin degradation. Plants either overexpressing or lacking PGX1 display alterations in total polygalacturonase activity, pectin molecular mass, and wall composition and also display higher proportions of flowers with extra petals, suggesting PGX1's involvement in floral organ patterning. These results reveal new roles for polygalacturonases in plant development.

  2. Simulated microgravity, Mars gravity, and 2g hypergravity affect cell cycle regulation, ribosome biogenesis, and epigenetics in Arabidopsis cell cultures.

    Science.gov (United States)

    Kamal, Khaled Y; Herranz, Raúl; van Loon, Jack J W A; Medina, F Javier

    2018-04-23

    Gravity is the only component of Earth environment that remained constant throughout the entire process of biological evolution. However, it is still unclear how gravity affects plant growth and development. In this study, an in vitro cell culture of Arabidopsis thaliana was exposed to different altered gravity conditions, namely simulated reduced gravity (simulated microgravity, simulated Mars gravity) and hypergravity (2g), to study changes in cell proliferation, cell growth, and epigenetics. The effects after 3, 14, and 24-hours of exposure were evaluated. The most relevant alterations were found in the 24-hour treatment, being more significant for simulated reduced gravity than hypergravity. Cell proliferation and growth were uncoupled under simulated reduced gravity, similarly, as found in meristematic cells from seedlings grown in real or simulated microgravity. The distribution of cell cycle phases was changed, as well as the levels and gene transcription of the tested cell cycle regulators. Ribosome biogenesis was decreased, according to levels and gene transcription of nucleolar proteins and the number of inactive nucleoli. Furthermore, we found alterations in the epigenetic modifications of chromatin. These results show that altered gravity effects include a serious disturbance of cell proliferation and growth, which are cellular functions essential for normal plant development.

  3. The TCP4 transcription factor of Arabidopsis blocks cell division in yeast at G1 → S transition

    International Nuclear Information System (INIS)

    Aggarwal, Pooja; Padmanabhan, Bhavna; Bhat, Abhay; Sarvepalli, Kavitha; Sadhale, Parag P.; Nath, Utpal

    2011-01-01

    Highlights: → TCP4 is a class II TCP transcription factor, that represses cell division in Arabidopsis. → TCP4 expression in yeast retards cell division by blocking G1 → S transition. → Genome-wide expression studies and Western analysis reveals stabilization of cell cycle inhibitor Sic1, as possible mechanism. -- Abstract: The TCP transcription factors control important aspects of plant development. Members of class I TCP proteins promote cell cycle by regulating genes directly involved in cell proliferation. In contrast, members of class II TCP proteins repress cell division. While it has been postulated that class II proteins induce differentiation signal, their exact role on cell cycle has not been studied. Here, we report that TCP4, a class II TCP protein from Arabidopsis that repress cell proliferation in developing leaves, inhibits cell division by blocking G1 → S transition in budding yeast. Cells expressing TCP4 protein with increased transcriptional activity fail to progress beyond G1 phase. By analyzing global transcriptional status of these cells, we show that expression of a number of cell cycle genes is altered. The possible mechanism of G1 → S arrest is discussed.

  4. Live imaging of companion cells and sieve elements in Arabidopsis leaves.

    Directory of Open Access Journals (Sweden)

    Thibaud Cayla

    Full Text Available The phloem is a complex tissue composed of highly specialized cells with unique subcellular structures and a compact organization that is challenging to study in vivo at cellular resolution. We used confocal scanning laser microscopy and subcellular fluorescent markers in companion cells and sieve elements, for live imaging of the phloem in Arabidopsis leaves. This approach provided a simple framework for identifying phloem cell types unambiguously. It highlighted the compactness of the meshed network of organelles within companion cells. By contrast, within the sieve elements, unknown bodies were observed in association with the PP2-A1:GFP, GFP:RTM1 and RTM2:GFP markers at the cell periphery. The phloem lectin PP2-A1:GFP marker was found in the parietal ground matrix. Its location differed from that of the P-protein filaments, which were visualized with SEOR1:GFP and SEOR2:GFP. PP2-A1:GFP surrounded two types of bodies, one of which was identified as mitochondria. This location suggested that it was embedded within the sieve element clamps, specific structures that may fix the organelles to each another or to the plasma membrane in the sieve tubes. GFP:RTM1 was associated with a class of larger bodies, potentially corresponding to plastids. PP2-A1:GFP was soluble in the cytosol of immature sieve elements. The changes in its subcellular localization during differentiation provide an in vivo blueprint for monitoring this process. The subcellular features obtained with these companion cell and sieve element markers can be used as landmarks for exploring the organization and dynamics of phloem cells in vivo.

  5. Differential impact of amino acids on OXPHOS system activity following carbohydrate starvation in Arabidopsis cell suspensions.

    Science.gov (United States)

    Cavalcanti, João Henrique F; Quinhones, Carla G S; Schertl, Peter; Brito, Danielle S; Eubel, Holger; Hildebrandt, Tatjana; Nunes-Nesi, Adriano; Braun, Hans-Peter; Araújo, Wagner L

    2017-12-01

    Plant respiration mostly depends on the activity of glycolysis and the oxidation of organic acids in the tricarboxylic acid cycle to synthesize ATP. However, during stress situations plant cells also use amino acids as alternative substrates to donate electrons through the electron-transfer flavoprotein (ETF)/ETF:ubiquinone oxidoreductase (ETF/ETFQO) complex to the mitochondrial electron transport chain (mETC). Given this, we investigated changes of the oxidative phosphorylation (OXPHOS) system in Arabidopsis thaliana cell culture under carbohydrate starvation supplied with a range of amino acids. Induction of isovaleryl-CoA dehydrogenase (IVDH) activity was observed under carbohydrate starvation which was associated with increased amounts of IVDH protein detected by immunoblotting. Furthermore, activities of the protein complexes of the mETC were reduced under carbohydrate starvation. We also observed that OXPHOS system activity behavior is differently affected by different amino acids and that proteins associated with amino acids catabolism are upregulated in cells following carbohydrate starvation. Collectively, our results support the contention that ETF/ETFQO is an essential pathway to donate electrons to the mETC and that amino acids are alternative substrates to maintain respiration under carbohydrate starvation. © 2017 Scandinavian Plant Physiology Society.

  6. ANGUSTIFOLIA mediates one of the multiple SCRAMBLED signaling pathways regulating cell growth pattern in Arabidopsis thaliana.

    Science.gov (United States)

    Kwak, Su-Hwan; Song, Sang-Kee; Lee, Myeong Min; Schiefelbein, John

    2015-09-25

    In Arabidopsis thaliana, an atypical leucine-rich repeat receptor-like kinase, SCRAMBLED (SCM), is required for multiple developmental processes including root epidermal cell fate determination, silique dehiscence, inflorescence growth, ovule morphogenesis, and tissue morphology. Previous work suggested that SCM regulates these multiple pathways using distinct mechanisms via interactions with specific downstream factors. ANGUSTIFOLIA (AN) is known to regulate cell and tissue morphogenesis by influencing cortical microtubule arrangement, and recently, the AN protein was reported to interact with the SCM protein. Therefore, we examined whether AN might be responsible for mediating some of the SCM-dependent phenotypes. We discovered that both scm and an mutant lines cause an abnormal spiral or twisting growth of roots, but only the scm mutant affected root epidermal patterning. The siliques of the an and scm mutants also exhibited spiral growth, as previously reported, but only the scm mutant altered silique dehiscence. Interestingly, we discovered that the spiral growth of roots and siliques of the scm mutant is rescued by a truncated SCM protein that lacks its kinase domain, and that a juxtamembrane domain of SCM was sufficient for AN binding in the yeast two-hybrid analysis. These results suggest that the AN protein is one of the critical downstream factors of SCM pathways specifically responsible for mediating its effects on cell/tissue morphogenesis through cortical microtubule arrangement. Copyright © 2015 Elsevier Inc. All rights reserved.

  7. Endogenous TasiRNAs mediate non-cell autonomous effects on gene regulation in Arabidopsis thaliana.

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    Rebecca Schwab

    Full Text Available BACKGROUND: Different classes of small RNAs (sRNAs refine the expression of numerous genes in higher eukaryotes by directing protein partners to complementary nucleic acids, where they mediate gene silencing. Plants encode a unique class of sRNAs, called trans-acting small interfering RNAs (tasiRNAs, which post-transcriptionally regulate protein-coding transcripts, as do microRNAs (miRNAs, and both sRNA classes control development through their targets. TasiRNA biogenesis requires multiple components of the siRNA pathway and also miRNAs. But while 21mer siRNAs originating from transgenes can mediate silencing across several cell layers, miRNA action seems spatially restricted to the producing or closely surrounding cells. PRINCIPAL FINDINGS: We have previously described the isolation of a genetrap reporter line for TAS3a, the major locus producing AUXIN RESPONS FACTOR (ARF-regulating tasiRNAs in the Arabidopsis shoot. Its activity is limited to the adaxial (upper side of leaf primordia, thus spatially isolated from ARF-activities, which are located in the abaxial (lower side. We show here by in situ hybridization and reporter fusions that the silencing activities of ARF-regulating tasiRNAs are indeed manifested non-cell autonomously to spatially control ARF activities. CONCLUSIONS/SIGNIFICANCE: Endogenous tasiRNAs are thus mediators of a mobile developmental signal and might provide effective gene silencing at a distance beyond the reach of most miRNAs.

  8. Involvement of Arabidopsis Hexokinase1 in Cell Death Mediated by Myo -Inositol Accumulation

    KAUST Repository

    Bruggeman, Quentin

    2015-06-05

    Programmed cell death (PCD) is essential for several aspects of plant life, including development and stress responses. We recently identified the mips1 mutant of Arabidopsis thaliana, which is deficient for the enzyme catalyzing the limiting step of myo-inositol (MI) synthesis. One of the most striking features of mips1 is the light-dependent formation of lesions on leaves due to salicylic acid (SA)-dependent PCD. Here, we identified a suppressor of PCD by screening for mutations that abolish the mips1 cell death phenotype. Our screen identified the hxk1 mutant, mutated in the gene encoding the hexokinase1 (HXK1) enzyme that catalyzes sugar phosphorylation and acts as a genuine glucose sensor. We show that HXK1 is required for lesion formation in mips1 due to alterations in MI content, via SA-dependant signaling. Using two catalytically inactive HXK1 mutants, we also show that hexokinase catalytic activity is necessary for the establishment of lesions in mips1. Gas chromatography-mass spectrometry analyses revealed a restoration of the MI content in mips1 hxk1 that it is due to the activity of the MIPS2 isoform, while MIPS3 is not involved. Our work defines a pathway of HXK1-mediated cell death in plants and demonstrates that two MIPS enzymes act cooperatively under a particular metabolic status, highlighting a novel checkpoint of MI homeostasis in plants. © 2015 American Society of Plant Biologists. All rights reserved.

  9. Impairment of Cellulose Synthases Required for Arabidopsis Secondary Cell Wall Formation Enhances Disease Resistance[W

    Science.gov (United States)

    Hernández-Blanco, Camilo; Feng, Dong Xin; Hu, Jian; Sánchez-Vallet, Andrea; Deslandes, Laurent; Llorente, Francisco; Berrocal-Lobo, Marta; Keller, Harald; Barlet, Xavier; Sánchez-Rodríguez, Clara; Anderson, Lisa K.; Somerville, Shauna; Marco, Yves; Molina, Antonio

    2007-01-01

    Cellulose is synthesized by cellulose synthases (CESAs) contained in plasma membrane–localized complexes. In Arabidopsis thaliana, three types of CESA subunits (CESA4/IRREGULAR XYLEM5 [IRX5], CESA7/IRX3, and CESA8/IRX1) are required for secondary cell wall formation. We report that mutations in these proteins conferred enhanced resistance to the soil-borne bacterium Ralstonia solanacearum and the necrotrophic fungus Plectosphaerella cucumerina. By contrast, susceptibility to these pathogens was not altered in cell wall mutants of primary wall CESA subunits (CESA1, CESA3/ISOXABEN RESISTANT1 [IXR1], and CESA6/IXR2) or POWDERY MILDEW–RESISTANT5 (PMR5) and PMR6 genes. Double mutants indicated that irx-mediated resistance was independent of salicylic acid, ethylene, and jasmonate signaling. Comparative transcriptomic analyses identified a set of common irx upregulated genes, including a number of abscisic acid (ABA)–responsive, defense-related genes encoding antibiotic peptides and enzymes involved in the synthesis and activation of antimicrobial secondary metabolites. These data as well as the increased susceptibility of ABA mutants (abi1-1, abi2-1, and aba1-6) to R. solanacearum support a direct role of ABA in resistance to this pathogen. Our results also indicate that alteration of secondary cell wall integrity by inhibiting cellulose synthesis leads to specific activation of novel defense pathways that contribute to the generation of an antimicrobial-enriched environment hostile to pathogens. PMID:17351116

  10. Functional Analysis of Cellulose and Xyloglucan in the Walls of Stomatal Guard Cells of Arabidopsis1[OPEN

    Science.gov (United States)

    Rui, Yue; Anderson, Charles T.

    2016-01-01

    Stomatal guard cells are pairs of specialized epidermal cells that control water and CO2 exchange between the plant and the environment. To fulfill the functions of stomatal opening and closure that are driven by changes in turgor pressure, guard cell walls must be both strong and flexible, but how the structure and dynamics of guard cell walls enable stomatal function remains poorly understood. To address this question, we applied cell biological and genetic analyses to investigate guard cell walls and their relationship to stomatal function in Arabidopsis (Arabidopsis thaliana). Using live-cell spinning disk confocal microscopy, we measured the motility of cellulose synthase (CESA)-containing complexes labeled by green fluorescent protein (GFP)-CESA3 and observed a reduced proportion of GFP-CESA3 particles colocalizing with microtubules upon stomatal closure. Imaging cellulose organization in guard cells revealed a relatively uniform distribution of cellulose in the open state and a more fibrillar pattern in the closed state, indicating that cellulose microfibrils undergo dynamic reorganization during stomatal movements. In cesa3je5 mutants defective in cellulose synthesis and xxt1 xxt2 mutants lacking the hemicellulose xyloglucan, stomatal apertures, changes in guard cell length, and cellulose reorganization were aberrant during fusicoccin-induced stomatal opening or abscisic acid-induced stomatal closure, indicating that sufficient cellulose and xyloglucan are required for normal guard cell dynamics. Together, these results provide new insights into how guard cell walls allow stomata to function as responsive mediators of gas exchange at the plant surface. PMID:26729799

  11. MALDI-TOF MS and CE-LIF Fingerprinting of Plant Cell Wall Polysaccharide Digests as a Screening Tool for Arabidopsis Cell Wall Mutants

    NARCIS (Netherlands)

    Westphal, Y.; Schols, H.A.; Voragen, A.G.J.; Gruppen, H.

    2010-01-01

    Cell wall materials derived from leaves and hypocotyls of Arabidopsis mutant and wild type plants have been incubated with a mixture of pure and well-defined pectinases, hemicellulases, and cellulases. The resulting oligosaccharides have been subjected to MALDI-TOF MS and CE-LIF analysis. MALDI-TOF

  12. Programmed cell death induced by high levels of cytokinin in Arabidopsis cultured cells is mediated by the cytokinin receptor CRE1/AHK4

    Czech Academy of Sciences Publication Activity Database

    Vescovi, M.; Riefler, M.; Gessuti, M.; Novák, Ondřej; Schmülling, T.; Lo Schiavo, F.

    2012-01-01

    Roč. 63, č. 7 (2012), s. 2825-2832 ISSN 0022-0957 Institutional research plan: CEZ:AV0Z50380511 Keywords : Arabidopsis cultured cells * cytokinin * histidine kinase cytokinin receptors Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 5.242, year: 2012

  13. Arabidopsis thaliana plants lacking the ARP2/3 complex show defects in cell wall assembly and auxin distribution.

    Science.gov (United States)

    Pratap Sahi, Vaidurya; Cifrová, Petra; García-González, Judith; Kotannal Baby, Innu; Mouillé, Gregory; Gineau, Emilie; Müller, Karel; Baluška, František; Soukup, Aleš; Petrášek, Jan; Schwarzerová, Katerina

    2017-12-25

    The cytoskeleton plays an important role in the synthesis of plant cell walls. Both microtubules and actin cytoskeleton are known to be involved in the morphogenesis of plant cells through their role in cell wall building. The role of ARP2/3-nucleated actin cytoskeleton in the morphogenesis of cotyledon pavement cells has been described before. Seedlings of Arabidopsis mutants lacking a functional ARP2/3 complex display specific cell wall-associated defects. In three independent Arabidopsis mutant lines lacking subunits of the ARP2/3 complex, phenotypes associated with the loss of the complex were analysed throughout plant development. Organ size and anatomy, cell wall composition, and auxin distribution were investigated. ARP2/3-related phenotype is associated with changes in cell wall composition, and the phenotype is manifested especially in mature tissues. Cell walls of mature plants contain less cellulose and a higher amount of homogalacturonan, and display changes in cell wall lignification. Vascular bundles of mutant inflorescence stems show a changed pattern of AUX1-YFP expression. Plants lacking a functional ARP2/3 complex have decreased basipetal auxin transport. The results suggest that the ARP2/3 complex has a morphogenetic function related to cell wall synthesis and auxin transport. © The Author(s) 2017. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  14. 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.

  15. ARABIDOPSIS HOMOLOG of TRITHORAX1 (ATX1) is required for cell production, patterning, and morphogenesis in root development

    OpenAIRE

    Napsucialy-Mendivil, Selene; Alvarez-Venegas, Raúl; Shishkova, Svetlana; Dubrovsky, Joseph G.

    2014-01-01

    ARABIDOPSIS HOMOLOG of TRITHORAX1 (ATX1/SDG27), a known regulator of flower development, encodes a H3K4histone methyltransferase that maintains a number of genes in an active state. In this study, the role of ATX1 in root development was evaluated. The loss-of-function mutant atx1-1 was impaired in primary root growth. The data suggest that ATX1 controls root growth by regulating cell cycle duration, cell production, and the transition from cell proliferation in the root apical meristem (RAM)...

  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. COBRA encodes a putative GPI-anchored protein, which is polarly localized and necessary for oriented cell expansion in Arabidopsis.

    Science.gov (United States)

    Schindelman, G; Morikami, A; Jung, J; Baskin, T I; Carpita, N C; Derbyshire, P; McCann, M C; Benfey, P N

    2001-05-01

    To control organ shape, plant cells expand differentially. The organization of the cellulose microfibrils in the cell wall is a key determinant of differential expansion. Mutations in the COBRA (COB) gene of Arabidopsis, known to affect the orientation of cell expansion in the root, are reported here to reduce the amount of crystalline cellulose in cell walls in the root growth zone. The COB gene, identified by map-based cloning, contains a sequence motif found in proteins that are anchored to the extracellular surface of the plasma membrane through a glycosylphosphatidylinositol (GPI) linkage. In animal cells, this lipid linkage is known to confer polar localization to proteins. The COB protein was detected predominately on the longitudinal sides of root cells in the zone of rapid elongation. Moreover, COB RNA levels are dramatically upregulated in cells entering the zone of rapid elongation. Based on these results, models are proposed for the role of COB as a regulator of oriented cell expansion.

  18. AMIODARONE INDUCES THE SYNTHESIS OF HSPS IN SACCHAROMYCES CEREVISIAE AND ARABIDOPSIS THALIANA CELLS

    Directory of Open Access Journals (Sweden)

    Pyatrikas D.V.

    2012-08-01

    Full Text Available Many biotic and abiotic stresses cause an increase of cytosolic Ca2+ level in cells. Calcium is one of the most important second messengers, regulating many various activities in the cell and was known to affect expression of stress activated genes. Mild heat shock induces the expression of heat shock proteins (Hsps which protect cell from drastic heat shock exposure. There are some literature data permitting to suggest that transient elevation of cytosolic Ca2+ level in plant cells is important for activation of Hsps expression. On the other hand mitochondria are known to regulate the intracellular calcium and reactive oxygen species signaling. It has been shown recently that mild heat shock induces hyperpolarization of inner mitochondrial membrane in plant and yeast cells and this event is critically important for activation of Hsps expression. To reveal the relationship between mitochondrial activity, intracellular calcium homeostasis and Hsps expression an antiarrhythmic drug amiodarone (AMD have been used. AMD is known to cause transient increase of cytosolic Ca2+ level in Saccharomyces cerevisiae. Obtained results have showed that AMD treatment induced the synthesis of Hsp104p in S. cerevisiae cells and Hsp101p in A. thaliana cell culture. Induction of Hsp104p synthesis leads to enhanced yeast capability to survive lethal heat shock exposure. Development of S. cerevisiae thermotolerance depended significantly on the presence of Hsp104p. Elevation of Hsp104p level in the result of AMD treatment was shown to be governed by activity of Msn2p and Msn4p transcription factors. Deletion of the MSN2 and MSN4 genes abrogated the AMD ability to induce Hsp104p synthesis. Mild heat shock and AMD treatment induced the hyperpolarization of the inner mitochondrial membrane in yeast and Arabidopsis cells which accompanied by HSP synthesis and development of thermotolerance. It was suggested that increase of cytosolic Ca2+ level after AMD treatment

  19. Polarized localization and borate-dependent degradation of the Arabidopsis borate transporter BOR1 in tobacco BY-2 cells.

    Science.gov (United States)

    Yamauchi, Noboru; Gosho, Tadashi; Asatuma, Satoru; Toyooka, Kiminori; Fujiwara, Toru; Matsuoka, Ken

    2013-01-01

    In Arabidopsis the borate transporter BOR1, which is located in the plasma membrane, is degraded in the presence of excess boron by an endocytosis-mediated mechanism. A similar mechanism was suggested in rice as excess boron decreased rice borate transporter levels, although in this case whether the decrease was dependent on an increase in degradation or a decrease in protein synthesis was not elucidated. To address whether the borate-dependent degradation mechanism is conserved among plant cells, we analyzed the fate of GFP-tagged BOR1 (BOR1-GFP) in transformed tobacco BY-2 cells. Cells expressing BOR1-GFP displayed GFP fluorescence at the plasma membrane, especially at the membrane between two attached cells. The plasma membrane signal was abolished when cells were incubated in medium with a high concentration of borate (3 to 5 mM). This decrease in BOR1-GFP signal was mediated by a specific degradation of the protein after internalization by endocytosis from the plasma membrane. Pharmacological analysis indicated that the decrease in BOR1-GFP largely depends on the increase in degradation rate and that the degradation was mediated by a tyrosine-motif and the actin cytoskeleton. Tyr mutants of BOR1-GFP, which has been shown to inhibit borate-dependent degradation in Arabidopsis root cells, did not show borate-dependent endocytosis in tobacco BY-2 cells. These findings indicate that the borate-dependent degradation machinery of the borate transporter is conserved among plant species.

  20. TCS1, a Microtubule-Binding Protein, Interacts with KCBP/ZWICHEL to Regulate Trichome Cell Shape in Arabidopsis thaliana.

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    Liangliang Chen

    2016-10-01

    Full Text Available How cell shape is controlled is a fundamental question in developmental biology, but the genetic and molecular mechanisms that determine cell shape are largely unknown. Arabidopsis trichomes have been used as a good model system to investigate cell shape at the single-cell level. Here we describe the trichome cell shape 1 (tcs1 mutants with the reduced trichome branch number in Arabidopsis. TCS1 encodes a coiled-coil domain-containing protein. Pharmacological analyses and observations of microtubule dynamics show that TCS1 influences the stability of microtubules. Biochemical analyses and live-cell imaging indicate that TCS1 binds to microtubules and promotes the assembly of microtubules. Further results reveal that TCS1 physically associates with KCBP/ZWICHEL, a microtubule motor involved in the regulation of trichome branch number. Genetic analyses indicate that kcbp/zwi is epistatic to tcs1 with respect to trichome branch number. Thus, our findings define a novel genetic and molecular mechanism by which TCS1 interacts with KCBP to regulate trichome cell shape by influencing the stability of microtubules.

  1. Coordinated Regulations of mRNA Synthesis and Decay during Cold Acclimation in Arabidopsis Cells.

    KAUST Repository

    Arae, Toshihiro

    2017-04-18

    Plants possess a cold acclimation system to acquire freezing tolerance through pre-exposure to non-freezing low temperatures. The transcriptional cascade of C-repeat binding factors (CBFs)/dehydration response element-binding factors (DREBs) is considered a major transcriptional regulatory pathway during cold acclimation. However, little is known regarding the functional significance of mRNA stability regulation in the response of gene expression to cold stress. The actual level of individual mRNAs is determined by a balance between mRNA synthesis and degradation. Therefore, it is important to assess the regulatory steps to increase our understanding of gene regulation. Here, we analyzed temporal changes in mRNA amounts and half-lives in response to cold stress in Arabidopsis cell cultures based on genome-wide analysis. In this mRNA decay array method, mRNA half-life measurements and microarray analyses were combined. In addition, temporal changes in the integrated value of transcription rates were estimated from the above two parameters using a mathematical approach. Our results showed that several cold-responsive genes, including Cold-regulated 15a, were relatively destabilized, whereas the mRNA amounts were increased during cold treatment by accelerating the transcription rate to overcome the destabilization. Considering the kinetics of mRNA synthesis and degradation, this apparently contradictory result supports that mRNA destabilization is advantageous for the swift increase in CBF-responsive genes in response to cold stress.

  2. Expression analysis of Arabidopsis vacuolar sorting receptor 3 reveals a putative function in guard cells.

    Science.gov (United States)

    Avila, Emily L; Brown, Michelle; Pan, Songqin; Desikan, Radhika; Neill, Steven J; Girke, Thomas; Surpin, Marci; Raikhel, Natasha V

    2008-01-01

    Vacuolar sorting receptors (VSRs) are responsible for the proper targeting of soluble cargo proteins to their destination compartments. The Arabidopsis genome encodes seven VSRs. In this work, the spatio-temporal expression of one of the members of this gene family, AtVSR3, was determined by RT-PCR and promoter::reporter gene fusions. AtVSR3 was expressed specifically in guard cells. Consequently, a reverse genetics approach was taken to determine the function of AtVSR3 by using RNA interference (RNAi) technology. Plants expressing little or no AtVSR3 transcript had a compressed life cycle, bolting approximately 1 week earlier and senescing up to 2 weeks earlier than the wild-type parent line. While the development and distribution of stomata in AtVSR3 RNAi plants appeared normal, stomatal function was altered. The guard cells of mutant plants did not close in response to abscisic acid treatment, and the mean leaf temperatures of the RNAi plants were on average 0.8 degrees C lower than both wild type and another vacuolar sorting receptor mutant, atvsr1-1. Furthermore, the loss of AtVSR3 protein caused the accumulation of nitric oxide and hydrogen peroxide, signalling molecules implicated in the regulation of stomatal opening and closing. Finally, proteomics and western blot analyses of cellular proteins isolated from wild-type and AtVSR3 RNAi leaves showed that phospholipase Dgamma, which may play a role in abscisic acid signalling, accumulated to higher levels in AtVSR3 RNAi guard cells. Thus, AtVSR3 may play an important role in responses to plant stress.

  3. Allocation of Heme is Differentially Regulated by Ferrochelatase Isoforms in Arabidopsis Cells

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    Nino Asuela Espinas

    2016-08-01

    Full Text Available Heme is involved in various biological processes as a cofactor of hemoproteins located in various organelles. In plant cells, heme is synthesized by two isoforms of plastid-localized ferrochelatase, FC1 and FC2. In this study, by characterizing Arabidopsis T-DNA insertional mutants, we showed that the allocation of heme is differentially regulated by ferrochelatase isoforms in plant cells. Analyses of weak (fc1-1 and null (fc1-2 mutants suggest that FC1-producing heme is required for initial growth of seedling development. In contrast, weak (fc2-1 and null (fc2-2 mutants of FC2 showed pale green leaves and retarded growth, indicating that FC2-producing heme is necessary for chloroplast development. During the initial growth stage, FC2 deficiency caused reduction of plastid cytochromes. In addition, although FC2 deficiency marginally affected the assembly of photosynthetic reaction center complexes, it caused relatively larger but insufficient light-harvesting antenna to reaction centers, resulting in lower efficiency of photosynthesis. In the later vegetative growth, however, fc2-2 recovered photosynthetic growth, showing that FC1-producing heme may complement the FC2 deficiency. On the other hand, reduced level of cytochromes in microsomal fraction was discovered in fc1-1, suggesting that FC1-producing heme is mainly allocated to extraplastidic organelles. Furthermore, the expression of FC1 is induced by the treatment of an elicitor flg22 while that of FC2 was reduced, and fc1-1 abolished the flg22-dependent induction of FC1 expression and peroxidase activity. Consequently, our results clarified that FC2 produces heme for the photosynthetic machinery in the chloroplast, while FC1 is the housekeeping enzyme providing heme cofactor to the entire cell. In addition, FC1 can partly complement FC2 deficiency and is also involved in defense against stressful conditions.

  4. Crosstalks between myo-inositol metabolism, programmed cell death and basal immunity in Arabidopsis.

    Directory of Open Access Journals (Sweden)

    Ping Hong Meng

    Full Text Available BACKGROUND: Although it is a crucial cellular process required for both normal development and to face stress conditions, the control of programmed cell death in plants is not fully understood. We previously reported the isolation of ATXR5 and ATXR6, two PCNA-binding proteins that could be involved in the regulation of cell cycle or cell death. A yeast two-hybrid screen using ATXR5 as bait captured AtIPS1, an enzyme which catalyses the committed step of myo-inositol (MI biosynthesis. atips1 mutants form spontaneous lesions on leaves, raising the possibility that MI metabolism may play a role in the control of PCD in plants. In this work, we have characterised atips1 mutants to gain insight regarding the role of MI in PCD regulation. METHODOLOGY/PRINCIPAL FINDINGS: - lesion formation in atips1 mutants depends of light intensity, is due to PCD as evidenced by TUNEL labelling of nuclei, and is regulated by phytohormones such as salicylic acid - MI and galactinol are the only metabolites whose accumulation is significantly reduced in the mutant, and supplementation of the mutant with these compounds is sufficient to prevent PCD - the transcriptome profile of the mutant is extremely similar to that of lesion mimic mutants such as cpr5, or wild-type plants infected with pathogens. CONCLUSION/SIGNIFICANCE: Taken together, our results provide strong evidence for the role of MI or MI derivatives in the regulation of PCD. Interestingly, there are three isoforms of IPS in Arabidopsis, but AtIPS1 is the only one harbouring a nuclear localisation sequence, suggesting that nuclear pools of MI may play a specific role in PCD regulation and opening new research prospects regarding the role of MI in the prevention of tumorigenesis. Nevertheless, the significance of the interaction between AtIPS1 and ATXR5 remains to be established.

  5. Real-time Recording of Cytosolic Calcium Levels in Arabidopsis thaliana Cell Cultures during Parabolic Flights

    Science.gov (United States)

    Neef, Maren; Ecke, Margret; Hampp, Rüdiger

    2015-07-01

    In plants, like in other organisms, calcium (Ca2+) is an important second messenger which participates in the conversion of environmental signals into molecular responses. There is increasing evidence, that sensing of changes in gravitation or reorientation of tissues is an example for such signaling cascades in which Ca2+ is involved. In order to determine g-dependent changes in the cytosolic calcium (Ca^{2+}_{ {cyt}}) concentration of plant cells, semisolid transgenic callus cell cultures of Arabidopsis thaliana (A.t.), expressing the calcium sensor YC3.6 (cameleon), were exposed to g-forces between 1.8 g and μ g during parabolic flights. Using such cells, intracellular calcium transients can be monitored by FRET in vivo and in real-time. Interestingly we observed a slight decrease of the Ca^{2+}_{ {cyt}} level during the hypergravity phases of a parabola but a significant increase of the Ca^{2+}_{ {cyt}} concentration during microgravity. Application of known Ca2+ inhibitors and antagonists yielded the following effects: nifedipine (Ca2+ channel blocker) showed no effect, whereas LaCl3, GdCl3 (both inhibitors of uptake at the plasma membrane), DPI (inhibitor of NADP oxidase), and DMSO (solvent) diminished the gravity-alteration-related Ca^{2+}_{ {cyt}} response. EGTA (binding of Ca2+) and eosin yellow (inhibitor of a plasma membrane-located Ca2+ pump) suppressed the respective Ca^{2+}_{ {cyt}} changes entirely. We thus conclude that the significant increase in Ca^{2+}_{ {cyt}} under microgravity is largely due to extracellular Ca2+ sources.

  6. A peroxidase-dependent apoplastic oxidative burst in cultured Arabidopsis cells functions in MAMP-elicited defense.

    Science.gov (United States)

    O'Brien, Jose A; Daudi, Arsalan; Finch, Paul; Butt, Vernon S; Whitelegge, Julian P; Souda, Puneet; Ausubel, Frederick M; Bolwell, G Paul

    2012-04-01

    Perception by plants of so-called microbe-associated molecular patterns (MAMPs) such as bacterial flagellin, referred to as pattern-triggered immunity, triggers a rapid transient accumulation of reactive oxygen species (ROS). We previously identified two cell wall peroxidases, PRX33 and PRX34, involved in apoplastic hydrogen peroxide (H2O2) production in Arabidopsis (Arabidopsis thaliana). Here, we describe the generation of Arabidopsis tissue culture lines in which the expression of PRX33 and PRX34 is knocked down by antisense expression of a heterologous French bean (Phaseolus vulgaris) peroxidase cDNA construct. Using these tissue culture lines and two inhibitors of ROS generation, azide and diphenylene iodonium, we found that perxoxidases generate about half of the H2O2 that accumulated in response to MAMP treatment and that NADPH oxidases and other sources such as mitochondria account for the remainder of the ROS. Knockdown of PRX33/PRX34 resulted in decreased expression of several MAMP-elicited genes, including MYB51, CYP79B2, and CYP81F2. Similarly, proteomic analysis showed that knockdown of PRX33/PRX34 led to the depletion of various MAMP-elicited defense-related proteins, including the two cysteine-rich peptides PDF2.2 and PDF2.3. Knockdown of PRX33/PRX34 also led to changes in the cell wall proteome, including increases in enzymes involved in cell wall remodeling, which may reflect enhanced cell wall expansion as a consequence of reduced H2O2-mediated cell wall cross-linking. Comparative metabolite profiling of a CaCl2 extract of the PRX33/PRX34 knockdown lines showed significant changes in amino acids, aldehydes, and keto acids but not fatty acids and sugars. Overall, these data suggest that PRX33/PRX34-generated ROS production is involved in the orchestration of pattern-triggered immunity in tissue culture cells.

  7. Quantitative expression analysis of selected transcription factors in pavement, basal and trichome cells of mature leaves from Arabidopsis thaliana.

    Science.gov (United States)

    Schliep, Martin; Ebert, Berit; Simon-Rosin, Ulrike; Zoeller, Daniela; Fisahn, Joachim

    2010-05-01

    Gene expression levels of several transcription factors from Arabidopsis thaliana that were described previously to be involved in leaf development and trichome formation were analysed in trichome, basal and pavement cells of mature leaves. Single cell samples of these three cells types were collected by glass micro-capillaries. Real-time reverse transcription (RT)-PCR was used to analyse expression patterns of the following transcription factors: MYB23, MYB55, AtHB1, FILAMENTOUS FLOWER (FIL)/YABBY1 (YAB1), TRIPTYCHON (TRY) and CAPRICE (CPC). A difference in the expression patterns of TRY and CPC was revealed. Contrary to the CPC expression pattern, no transcripts of TRY could be detected in pavement cells. FIL/YAB1 was exclusively expressed in trichome cells. AtHB1 was highly expressed throughout all three cell types. MYB55 was higher expressed in basal cells than in trichome and pavement cells. MYB23 showed a pattern of low expression in pavement cells, medium in basal cells and high expression in trichomes. Expression patterns obtained by single cell sampling and real-time RT-PCR were compared to promoter GUS fusions of the selected transcription factors. Therefore, we regenerated two transgenic Arabidopsis lines that expressed the GUS reporter gene under control of the promoters of MYB55 and YAB1. In conclusion, despite their function in leaf morphogenesis, all six transcription factors were detected in mature leaves. Furthermore, single cell sampling and promoter GUS staining patterns demonstrated the predominant presence of MYB55 in basal cells as compared to pavement cells and trichomes.

  8. Arabidopsis VARIEGATED 3 encodes a chloroplasttargeted, zinc-finger protein required for chloroplast and palisade cell development

    DEFF Research Database (Denmark)

    Næsted, Henrik; Holm, A.; Jenkins, T.

    2004-01-01

    The stable, recessive Arabidopsis variegated 3 (var3) mutant exhibits a variegated phenotype due to somatic areas lacking or containing developmentally retarded chloroplasts and greatly reduced numbers of palisade cells. The VAR3 gene, isolated by transposon tagging, encodes the 85.9 kDa VAR3...... that pigment profiles are qualitatively similar in wild type and var3, although var3 accumulates lower levels of chlorophylls and carotenoids. These results indicate that VAR3 is a part of a protein complex required for normal chloroplast and palisade cell development....

  9. 3D Plant Cell Architecture of Arabidopsis thaliana (Brassicaceae Using Focused Ion Beam–Scanning Electron Microscopy

    Directory of Open Access Journals (Sweden)

    Bhawana

    2014-06-01

    Full Text Available Premise of the study: Focused ion beam–scanning electron microscopy (FIB-SEM combines the ability to sequentially mill the sample surface and obtain SEM images that can be used to create 3D renderings with micron-level resolution. We have applied FIB-SEM to study Arabidopsis cell architecture. The goal was to determine the efficacy of this technique in plant tissue and cellular studies and to demonstrate its usefulness in studying cell and organelle architecture and distribution. Methods: Seed aleurone, leaf mesophyll, stem cortex, root cortex, and petal lamina from Arabidopsis were fixed and embedded for electron microscopy using protocols developed for animal tissues and modified for use with plant cells. Each sample was sectioned using the FIB and imaged with SEM. These serial images were assembled to produce 3D renderings of each cell type. Results: Organelles such as nuclei and chloroplasts were easily identifiable, and other structures such as endoplasmic reticula, lipid bodies, and starch grains were distinguishable in each tissue. Discussion: The application of FIB-SEM produced 3D renderings of five plant cell types and offered unique views of their shapes and internal content. These results demonstrate the usefulness of FIB-SEM for organelle distribution and cell architecture studies.

  10. Arabidopsis brassinosteroid biosynthetic mutant dwarf7-1 exhibits slower rates of cell division and shoot induction

    Directory of Open Access Journals (Sweden)

    Schulz Burkhard

    2010-12-01

    Full Text Available Abstract Background Plant growth depends on both cell division and cell expansion. Plant hormones, including brassinosteroids (BRs, are central to the control of these two cellular processes. Despite clear evidence that BRs regulate cell elongation, their roles in cell division have remained elusive. Results Here, we report results emphasizing the importance of BRs in cell division. An Arabidopsis BR biosynthetic mutant, dwarf7-1, displayed various characteristics attributable to slower cell division rates. We found that the DWARF4 gene which encodes for an enzyme catalyzing a rate-determining step in the BR biosynthetic pathways, is highly expressed in the actively dividing callus, suggesting that BR biosynthesis is necessary for dividing cells. Furthermore, dwf7-1 showed noticeably slower rates of callus growth and shoot induction relative to wild-type control. Flow cytometric analyses of the nuclei derived from either calli or intact roots revealed that the cell division index, which was represented as the ratio of cells at the G2/M vs. G1 phases, was smaller in dwf7-1 plants. Finally, we found that the expression levels of the genes involved in cell division and shoot induction, such as PROLIFERATING CELL NUCLEAR ANTIGEN2 (PCNA2 and ENHANCER OF SHOOT REGENERATION2 (ESR2, were also lower in dwf7-1 as compared with wild type. Conclusions Taken together, results of callus induction, shoot regeneration, flow cytometry, and semi-quantitative RT-PCR analysis suggest that BRs play important roles in both cell division and cell differentiation in Arabidopsis.

  11. Evaluation of cell wall preparations for proteomics: a new procedure for purifying cell walls from Arabidopsis hypocotyls

    Directory of Open Access Journals (Sweden)

    Canut Hervé

    2006-05-01

    Full Text Available Abstract Background The ultimate goal of proteomic analysis of a cell compartment should be the exhaustive identification of resident proteins; excluding proteins from other cell compartments. Reaching such a goal closely depends on the reliability of the isolation procedure for the cell compartment of interest. Plant cell walls possess specific difficulties: (i the lack of a surrounding membrane may result in the loss of cell wall proteins (CWP during the isolation procedure, (ii polysaccharide networks of cellulose, hemicelluloses and pectins form potential traps for contaminants such as intracellular proteins. Several reported procedures to isolate cell walls for proteomic analyses led to the isolation of a high proportion (more than 50% of predicted intracellular proteins. Since isolated cell walls should hold secreted proteins, one can imagine alternative procedures to prepare cell walls containing a lower proportion of contaminant proteins. Results The rationales of several published procedures to isolate cell walls for proteomics were analyzed, with regard to the bioinformatic-predicted subcellular localization of the identified proteins. Critical steps were revealed: (i homogenization in low ionic strength acid buffer to retain CWP, (ii purification through increasing density cushions, (iii extensive washes with a low ionic strength acid buffer to retain CWP while removing as many cytosolic proteins as possible, and (iv absence of detergents. A new procedure was developed to prepare cell walls from etiolated hypocotyls of Arabidopsis thaliana. After salt extraction, a high proportion of proteins predicted to be secreted was released (73%, belonging to the same functional classes as proteins identified using previously described protocols. Finally, removal of intracellular proteins was obtained using detergents, but their amount represented less than 3% in mass of the total protein extract, based on protein quantification. Conclusion The

  12. A WUSCHEL-Independent Stem Cell Specification Pathway Is Repressed by PHB, PHV and CNA in Arabidopsis

    Science.gov (United States)

    Lee, Chunghee; Clark, Steven E.

    2015-01-01

    The homeostatic maintenance of stem cells that carry out continuous organogenesis at the shoot meristem is crucial for plant development. Key known factors act to signal between the stem cells and an underlying group of cells thought to act as the stem cell niche. In Arabidopsis thaliana the homeodomain transcription factor WUSCHEL (WUS) is essential for stem cell initiation and maintenance at shoot and flower meristems. Recent data suggest that the WUS protein may move from the niche cells directly into the stem cells to maintain stem cell identity. Here we provide evidence for a second, previously unknown, pathway for stem cell specification at shoot and flower meristems that bypasses the requirement for WUS. We demonstrate that this novel stem cell specification pathway is normally repressed by the activity of the HD-zip III transcription factors PHABULOSA (PHB), PHAVOLUTA (PHV) and CORONA (CNA). When de-repressed, this second stem cell pathway leads to an accumulation of stem cells and an enlargement of the stem cell niche. When de-repressed in a wus mutant background, this second stem cell pathway leads to functional meristems with largely normal cell layering and meristem morphology, activation of WUS cis regulatory elements, and extensive, but not indeterminate, organogenesis. Thus, WUS is largely dispensable for stem cell specification and meristem function, suggesting a set of key stem cell specification factors, competitively regulated by WUS and PHB/PHV/CNA, remain unidentified. PMID:26011610

  13. The Arabidopsis GASA10 gene encodes a cell wall protein strongly expressed in developing anthers and seeds.

    Science.gov (United States)

    Trapalis, Menelaos; Li, Song Feng; Parish, Roger W

    2017-07-01

    The Arabidopsis GASA10 gene encodes a GAST1-like (Gibberellic Acid-Stimulated) protein. Reporter gene analysis identified consistent expression in anthers and seeds. In anthers expression was developmentally regulated, first appearing at stage 7 of anther development and reaching a maximum at stage 11. Strongest expression was in the tapetum and developing microspores. GASA10 expression also occurred throughout the seed and in root vasculature. GASA10 was shown to be transported to the cell wall. Using GASA1 and GASA6 as positive controls, gibberellic acid was found not to induce GASA10 expression in Arabidopsis suspension cells. Overexpression of GASA10 (35S promoter-driven) resulted in a reduction in silique elongation. GASA10 shares structural similarities to the antimicrobial peptide snakin1, however, purified GASA10 failed to influence the growth of a variety of bacterial and fungal species tested. We propose cell wall associated GASA proteins are involved in regulating the hydroxyl radical levels at specific sites in the cell wall to facilitate wall growth (regulating cell wall elongation). Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Catalase and NO CATALASE ACTIVITY1 Promote Autophagy-Dependent Cell Death in Arabidopsis[C][W][OPEN

    Science.gov (United States)

    Hackenberg, Thomas; Juul, Trine; Auzina, Aija; Gwiżdż, Sonia; Małolepszy, Anna; Van Der Kelen, Katrien; Dam, Svend; Bressendorff, Simon; Lorentzen, Andrea; Roepstorff, Peter; Lehmann Nielsen, Kåre; Jørgensen, Jan-Elo; Hofius, Daniel; Breusegem, Frank Van; Petersen, Morten; Andersen, Stig Uggerhøj

    2013-01-01

    Programmed cell death often depends on generation of reactive oxygen species, which can be detoxified by antioxidative enzymes, including catalases. We previously isolated catalase-deficient mutants (cat2) in a screen for resistance to hydroxyurea-induced cell death. Here, we identify an Arabidopsis thaliana hydroxyurea-resistant autophagy mutant, atg2, which also shows reduced sensitivity to cell death triggered by the bacterial effector avrRpm1. To test if catalase deficiency likewise affected both hydroxyurea and avrRpm1 sensitivity, we selected mutants with extremely low catalase activities and showed that they carried mutations in a gene that we named NO CATALASE ACTIVITY1 (NCA1). nca1 mutants showed severely reduced activities of all three catalase isoforms in Arabidopsis, and loss of NCA1 function led to strong suppression of RPM1-triggered cell death. Basal and starvation-induced autophagy appeared normal in the nca1 and cat2 mutants. By contrast, autophagic degradation induced by avrRpm1 challenge was compromised, indicating that catalase acted upstream of immunity-triggered autophagy. The direct interaction of catalase with reactive oxygen species could allow catalase to act as a molecular link between reactive oxygen species and the promotion of autophagy-dependent cell death. PMID:24285797

  15. Multi-omics analysis identifies genes mediating the extension of cell walls in the Arabidopsis thaliana root elongation zone

    DEFF Research Database (Denmark)

    Wilson, Michael H; Holman, Tara J; Sørensen, Iben

    2015-01-01

    Plant cell wall composition is important for regulating growth rates, especially in roots. However, neither analyses of cell wall composition nor transcriptomes on their own can comprehensively reveal which genes and processes are mediating growth and cell elongation rates. This study reveals...... the benefits of carrying out multiple analyses in combination. Sections of roots from five anatomically and functionally defined zones in Arabidopsis thaliana were prepared and divided into three biological replicates. We used glycan microarrays and antibodies to identify the major classes of glycans......)cellular localization of many epitopes. Extensins were localized in epidermal and cortex cell walls, while AGP glycans were specific to different tissues from root-hair cells to the stele. The transcriptome analysis found several gene families peaking in the REZ. These included a large family of peroxidases (which...

  16. Arabidopsis thaliana Somatic Embryogenesis Receptor Kinase 1 protein is present in sporophytic and gametophytic cells and undergoes endocytosis

    DEFF Research Database (Denmark)

    Kwaaitaal, Mark Adrianus Cornelis J; de Vries, S C; Russinova, E

    2005-01-01

    Arabidopsis thaliana plants expressing AtSERK1 fused to yellow-fluorescent protein were generated. Fluorescence was detected predominantly at the cell periphery, most likely the plasma membrane, of cells in ovules, embryo sacs, anthers, and embryos and in seedlings. The AtSERK1 protein was detected...... in diverse cell types including the epidermis and the vascular bundles. In some cells, fluorescent receptors were seen in small vesicle-like compartments. After application of the fungal toxin Brefeldin A, the fluorescent receptors were rapidly internalized in the root meristem and root vascular tissue. We...... conclude that the AtSERK1 receptor functions in a common signalling pathway employed in both sporophytic and gametophytic cells....

  17. Three pectin methylesterase inhibitors protect cell wall integrity for arabidopsis immunity to Botrytis

    DEFF Research Database (Denmark)

    Lionetti, Vincenzo; Fabri, Eleonora; Caroli, Monica De

    2017-01-01

    to the control plants. A higher stimulation of the fungal oxalic acid biosynthetic pathway also can contribute to the higher susceptibility of pmei mutants. The lack of PMEI expression does not affect hemicellulose strengthening, callose deposition, and the synthesis of structural defense proteins, proposed...... is posttranscriptionally regulated by endogenous protein inhibitors (PMEIs). Here, AtPMEI10, AtPMEI11, and AtPMEI12 are identified as functional PMEIs induced in Arabidopsis (Arabidopsis thaliana) during B. cinerea infection. AtPMEI expression is strictly regulated by jasmonic acid and ethylene signaling, while only At...

  18. Rapid and dynamic subcellular reorganization following mechanical stimulation of Arabidopsis epidermal cells mimics responses to fungal and oomycete attack

    Directory of Open Access Journals (Sweden)

    Takemoto Daigo

    2008-06-01

    Full Text Available Abstract Background Plant cells respond to the presence of potential fungal or oomycete pathogens by mounting a basal defence response that involves aggregation of cytoplasm, reorganization of cytoskeletal, endomembrane and other cell components and development of cell wall appositions beneath the infection site. This response is induced by non-adapted, avirulent and virulent pathogens alike, and in the majority of cases achieves penetration resistance against the microorganism on the plant surface. To explore the nature of signals that trigger this subcellular response and to determine the timing of its induction, we have monitored the reorganization of GFP-tagged actin, microtubules, endoplasmic reticulum (ER and peroxisomes in Arabidopsis plants – after touching the epidermal surface with a microneedle. Results Within 3 to 5 minutes of touching the surface of Arabidopsis cotyledon epidermal cells with fine glass or tungsten needles, actin microfilaments, ER and peroxisomes began to accumulate beneath the point of contact with the needle. Formation of a dense patch of actin was followed by focusing of actin cables on the site of contact. Touching the cell surface induced localized depolymerization of microtubules to form a microtubule-depleted zone surrounding a dense patch of GFP-tubulin beneath the needle tip. The concentration of actin, GFP-tubulin, ER and peroxisomes remained focused on the contact site as the needle moved across the cell surface and quickly dispersed when the needle was removed. Conclusion Our results show that plant cells can detect the gentle pressure of a microneedle on the epidermal cell surface and respond by reorganizing subcellular components in a manner similar to that induced during attack by potential fungal or oomycete pathogens. The results of our study indicate that during plant-pathogen interactions, the basal defence response may be induced by the plant's perception of the physical force exerted by the

  19. Functional and Structural Characterization of a Receptor-Like Kinase Involved in Germination and Cell Expansion in Arabidopsis

    Science.gov (United States)

    Wu, Zhen; Liang, Shan; Song, Wen; Lin, Guangzhong; Wang, Weiguang; Zhang, Heqiao; Han, Zhifu; Chai, Jijie

    2017-01-01

    Leucine-rich repeat receptor-like kinases (LRR-RLKs) are widespread in different plant species and play important roles in growth and development. Germination inhibition is vital for the completion of seed maturation and cell expansion is a fundamental cellular process driving plant growth. Here, we report genetic and structural characterizations of a functionally uncharacterized LRR-RLK, named GRACE (Germination Repression and Cell Expansion receptor-like kinase). Overexpression of GRACE in Arabidopsis exhibited delayed germination, enlarged cotyledons, rosette leaves and stubbier petioles. Conversely, these phenotypes were reversed in the T-DNA insertion knock-down mutant grace-1 plants. A crystal structure of the extracellular domain of GRACE (GRACE-LRR) determined at the resolution of 3.0 Å revealed that GRACE-LRR assumed a right-handed super-helical structure with an island domain (ID). Structural comparison showed that structure of the ID in GRACE-LRR is strikingly different from those observed in other LRR-RLKs. This structural observation implies that GRACE might perceive a new ligand for signaling. Collectively, our data support roles of GRACE in repressing seed germination and promoting cell expansion of Arabidopsis, presumably by perception of unknown ligand(s). PMID:29213277

  20. Plant-specific Histone Deacetylases HDT½ Regulate GIBBERELLIN 2-OXIDASE 2 Expression to Control Arabidopsis Root Meristem Cell Number

    KAUST Repository

    Li, Huchen

    2017-08-31

    Root growth is modulated by environmental factors and depends on cell production in the root meristem (RM). New cells in the meristem are generated by stem cells and transit-amplifying cells, which together determine RM cell number. Transcription factors and chromatin-remodelling factors have been implicated in regulating the switch from stem cells to transit-amplifying cells. Here we show that two Arabidopsis thaliana paralogs encoding plant-specific histone deacetylases, HDT1 and HDT2, regulate a second switch from transit-amplifying cells to expanding cells. Knockdown of HDT½ (hdt1,2i) results in an earlier switch and causes a reduced RM cell number. Our data show that HDT½ negatively regulate the acetylation level of the C19-GIBBERELLIN 2-OXIDASE 2 (GA2ox2) locus and repress the expression of GA2ox2 in the RM and elongation zone. Overexpression of GA2ox2 in the RM phenocopies the hdt1,2i phenotype. Conversely, knockout of GA2ox2 partially rescues the root growth defect of hdt1,2i. These results suggest that by repressing the expression of GA2ox2, HDT½ likely fine-tune gibberellin metabolism and they are crucial for regulating the switch from cell division to expansion to determine RM cell number. We propose that HDT½ function as part of a mechanism that modulates root growth in response to environmental factors.

  1. Engineering of red cells of Arabidopsis thaliana and comparative genome-wide gene expression analysis of red cells versus wild-type cells.

    Science.gov (United States)

    Shi, Ming-Zhu; Xie, De-Yu

    2011-04-01

    We report metabolic engineering of Arabidopsis red cells and genome-wide gene expression analysis associated with anthocyanin biosynthesis and other metabolic pathways between red cells and wild-type (WT) cells. Red cells of A. thaliana were engineered for the first time from the leaves of production of anthocyanin pigment 1-Dominant (pap1-D). These red cells produced seven anthocyanin molecules including a new one that was characterized by LC-MS analysis. Wild-type cells established as a control did not produce anthocyanins. A genome-wide microarray analysis revealed that nearly 66 and 65% of genes in the genome were expressed in the red cells and wild-type cells, respectively. In comparison with the WT cells, 3.2% of expressed genes in the red cells were differentially expressed. The expression levels of 14 genes involved in the biosynthetic pathway of anthocyanin were significantly higher in the red cells than in the WT cells. Microarray and RT-PCR analyses demonstrated that the TTG1-GL3/TT8-PAP1 complex regulated the biosynthesis of anthocyanins. Furthermore, most of the genes with significant differential expression levels in the red cells versus the WT cells were characterized with diverse biochemical functions, many of which were mapped to different metabolic pathways (e.g., ribosomal protein biosynthesis, photosynthesis, glycolysis, glyoxylate metabolism, and plant secondary metabolisms) or organelles (e.g., chloroplast). We suggest that the difference in gene expression profiles between the two cell lines likely results from cell types, the overexpression of PAP1, and the high metabolic flux toward anthocyanins.

  2. Arabidopsis RETINOBLASTOMA RELATED directly regulates DNA damage responses through functions beyond cell cycle control

    Czech Academy of Sciences Publication Activity Database

    Horvath, B.M.; Kourová, Hana; Nagy, S.; Nemeth, E.; Magyar, Z.; Papdi, C.; Ahmad, Z.; Sanchez-Perez, G.F.; Perilli, S.; Blilou, I.; Pettko-Szandtner, A.; Darula, Z.; Meszaros, T.; Binarová, Pavla; Bogre, L.; Scheres, B.

    2017-01-01

    Roč. 36, č. 9 (2017), s. 1261-1278 ISSN 0261-4189 R&D Projects: GA ČR GA15-11657S Institutional support: RVO:61388971 Keywords : Arabidopsis * BRCA1 * DNA damage response Subject RIV: EE - Microbiology, Virology OBOR OECD: Microbiology Impact factor: 9.792, year: 2016

  3. 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

  4. The age-dependent epigenetic and physiological changes in an Arabidopsis T87 cell suspension culture during long-term cultivation

    International Nuclear Information System (INIS)

    Kwiatkowska, Aleksandra; Zebrowski, Jacek; Oklejewicz, Bernadetta; Czarnik, Justyna; Halibart-Puzio, Joanna; Wnuk, Maciej

    2014-01-01

    Highlights: • A decrease in proliferation rate during long-term cultivation of Arabidopsis cells. • Age-dependent increase in senescence-associated gene expression in Arabidopsis cells. • Age-related increase in DNA methylation, H3K9me2, and H3K27me3 in Arabidopsis cells. • High potential of photosynthetic efficiency of long-term cultured Arabidopsis cells. - Abstract: Plant cell suspension cultures represent good model systems applicable for both basic research and biotechnological purposes. Nevertheless, it is widely known that a prolonged in vitro cultivation of plant cells is associated with genetic and epigenetic instabilities, which may limit the usefulness of plant lines. In this study, the age-dependent epigenetic and physiological changes in an asynchronous Arabidopsis T87 cell culture were examined. A prolonged cultivation period was found to be correlated with a decrease in the proliferation rate and a simultaneous increase in the expression of senescence-associated genes, indicating that the aging process started at the late growth phase of the culture. In addition, increases in the heterochromatin-specific epigenetic markers, i.e., global DNA methylation, H3K9 dimethylation, and H3K27 trimethylation, were observed, suggesting the onset of chromatin condensation, a hallmark of the early stages of plant senescence. Although the number of live cells decreased with an increase in the age of the culture, the remaining viable cells retained a high potential to efficiently perform photosynthesis and did not exhibit any symptoms of photosystem II damage

  5. The age-dependent epigenetic and physiological changes in an Arabidopsis T87 cell suspension culture during long-term cultivation

    Energy Technology Data Exchange (ETDEWEB)

    Kwiatkowska, Aleksandra, E-mail: A.Kwiatkows@gmail.com [Department of Botany, University of Rzeszow, Kolbuszowa (Poland); Zebrowski, Jacek [Department of Plant Physiology, University of Rzeszow, Kolbuszowa (Poland); Oklejewicz, Bernadetta [Department of Genetics, University of Rzeszow, Kolbuszowa (Poland); Czarnik, Justyna [Department of Botany, University of Rzeszow, Kolbuszowa (Poland); Halibart-Puzio, Joanna [Department of Plant Physiology, University of Rzeszow, Kolbuszowa (Poland); Wnuk, Maciej [Department of Genetics, University of Rzeszow, Kolbuszowa (Poland)

    2014-05-02

    Highlights: • A decrease in proliferation rate during long-term cultivation of Arabidopsis cells. • Age-dependent increase in senescence-associated gene expression in Arabidopsis cells. • Age-related increase in DNA methylation, H3K9me2, and H3K27me3 in Arabidopsis cells. • High potential of photosynthetic efficiency of long-term cultured Arabidopsis cells. - Abstract: Plant cell suspension cultures represent good model systems applicable for both basic research and biotechnological purposes. Nevertheless, it is widely known that a prolonged in vitro cultivation of plant cells is associated with genetic and epigenetic instabilities, which may limit the usefulness of plant lines. In this study, the age-dependent epigenetic and physiological changes in an asynchronous Arabidopsis T87 cell culture were examined. A prolonged cultivation period was found to be correlated with a decrease in the proliferation rate and a simultaneous increase in the expression of senescence-associated genes, indicating that the aging process started at the late growth phase of the culture. In addition, increases in the heterochromatin-specific epigenetic markers, i.e., global DNA methylation, H3K9 dimethylation, and H3K27 trimethylation, were observed, suggesting the onset of chromatin condensation, a hallmark of the early stages of plant senescence. Although the number of live cells decreased with an increase in the age of the culture, the remaining viable cells retained a high potential to efficiently perform photosynthesis and did not exhibit any symptoms of photosystem II damage.

  6. The Organization Pattern of Root Border-Like Cells of Arabidopsis Is Dependent on Cell Wall Homogalacturonan12[C][W

    Science.gov (United States)

    Durand, Caroline; Vicré-Gibouin, Maïté; Follet-Gueye, Marie Laure; Duponchel, Ludovic; Moreau, Myriam; Lerouge, Patrice; Driouich, Azeddine

    2009-01-01

    Border-like cells are released by Arabidopsis (Arabidopsis thaliana) root tips as organized layers of several cells that remain attached to each other rather than completely detached from each other, as is usually observed in border cells of many species. Unlike border cells, cell attachment between border-like cells is maintained after their release into the external environment. To investigate the role of cell wall polysaccharides in the attachment and organization of border-like cells, we have examined their release in several well-characterized mutants defective in the biosynthesis of xyloglucan, cellulose, or pectin. Our data show that among all mutants examined, only quasimodo mutants (qua1-1 and qua2-1), which have been characterized as producing less homogalacturonan, had an altered border-like cell phenotype as compared with the wild type. Border-like cells in both lines were released as isolated cells separated from each other, with the phenotype being much more pronounced in qua1-1 than in qua2-1. Further analysis of border-like cells in the qua1-1 mutant using immunocytochemistry and a set of anti-cell wall polysaccharide antibodies showed that the loss of the wild-type phenotype was accompanied by (1) a reduction in homogalacturonan-JIM5 epitope in the cell wall of border-like cells, confirmed by Fourier transform infrared microspectrometry, and (2) the secretion of an abundant mucilage that is enriched in xylogalacturonan and arabinogalactan-protein epitopes, in which the cells are trapped in the vicinity of the root tip. PMID:19448034

  7. Conserved CDC20 cell cycle functions are carried out by two of the five isoforms in Arabidopsis thaliana.

    Directory of Open Access Journals (Sweden)

    Zoltán Kevei

    Full Text Available The CDC20 and Cdh1/CCS52 proteins are substrate determinants and activators of the Anaphase Promoting Complex/Cyclosome (APC/C E3 ubiquitin ligase and as such they control the mitotic cell cycle by targeting the degradation of various cell cycle regulators. In yeasts and animals the main CDC20 function is the destruction of securin and mitotic cyclins. Plants have multiple CDC20 gene copies whose functions have not been explored yet. In Arabidopsis thaliana there are five CDC20 isoforms and here we aimed at defining their contribution to cell cycle regulation, substrate selectivity and plant development.Studying the gene structure and phylogeny of plant CDC20s, the expression of the five AtCDC20 gene copies and their interactions with the APC/C subunit APC10, the CCS52 proteins, components of the mitotic checkpoint complex (MCC and mitotic cyclin substrates, conserved CDC20 functions could be assigned for AtCDC20.1 and AtCDC20.2. The other three intron-less genes were silent and specific for Arabidopsis. We show that AtCDC20.1 and AtCDC20.2 are components of the MCC and interact with mitotic cyclins with unexpected specificity. AtCDC20.1 and AtCDC20.2 are expressed in meristems, organ primordia and AtCDC20.1 also in pollen grains and developing seeds. Knocking down both genes simultaneously by RNAi resulted in severe delay in plant development and male sterility. In these lines, the meristem size was reduced while the cell size and ploidy levels were unaffected indicating that the lower cell number and likely slowdown of the cell cycle are the cause of reduced plant growth.The intron-containing CDC20 gene copies provide conserved and redundant functions for cell cycle progression in plants and are required for meristem maintenance, plant growth and male gametophyte formation. The Arabidopsis-specific intron-less genes are possibly "retrogenes" and have hitherto undefined functions or are pseudogenes.

  8. Wall ingrowth deposition in phloem parenchyma transfer cells in Arabidopsis: Heteroblastic variations and a potential role in pathogen defence.

    Science.gov (United States)

    Nguyen, Suong T T; McCurdy, David W

    2017-06-03

    Transfer cell (TCs) develop unique wall ingrowth networks which amplify plasma membrane surface area and thus maximize nutrient transporter density at key anatomic sites for nutrient exchange within plants and their external environment. These sites fall into 4 main groups corresponding to 4 categories of trans-membrane flux: absorption/secretion of solutes from or to the external environment, and absorption/secretion of solutes from or to internal, extra-cytoplasmic compartments. Research on TC biology over recent decades has demonstrated correlations between wall ingrowth deposition in TCs and enhanced transport capacity in many major agricultural species such as pea, fava bean, cotton and maize. Consequently, there is general consensus that the existence of wall ingrowth morphology implies an augmentation in membrane transport capacity. However, this may not be entirely applicable for phloem parenchyma (PP) TCs in Arabidopsis. Our recent survey of PP TC abundance and distribution in Arabidopsis veins indicated that PP TC development reflects heteroblastic status. A consequence of this observation is the suggestion that PP TCs, or at least wall ingrowth deposition in these cells, potentially act as a physical barrier to defend access of invading pathogens to sugar-rich sieve elements rather than solely in facilitating the export of photoassimilate from collection phloem in leaves.

  9. Co-localisation studies of Arabidopsis SR splicing factors reveal different types of speckles in plant cell nuclei

    International Nuclear Information System (INIS)

    Lorkovic, Zdravko J.; Hilscher, Julia; Barta, Andrea

    2008-01-01

    SR proteins are multidomain splicing factors which are important for spliceosome assembly and for regulation of alternative splicing. In mammalian nuclei these proteins localise to speckles from where they are recruited to transcription sites. By using fluorescent protein fusion technology and different experimental approaches it has been shown that Arabidopsis SR proteins, in addition to diffuse nucleoplasmic staining, localise into an irregular nucleoplasmic network resembling speckles in mammalian cells. As Arabidopsis SR proteins fall into seven conserved sub-families we investigated co-localisation of members of the different sub-families in transiently transformed tobacco protoplast. Here we demonstrate the new finding that members of different SR protein sub-families localise into distinct populations of nuclear speckles with no, partial or complete co-localisation. This is particularly interesting as we also show that these proteins do interact in a yeast two-hybrid assay as well as in pull-down and in co-immunopreciptiation assays. Our data raise the interesting possibility that SR proteins are partitioned into distinct populations of nuclear speckles to allow a more specific recruitment to the transcription/pre-mRNA processing sites of particular genes depending on cell type and developmental stage

  10. Model-Based Analysis of Arabidopsis Leaf Epidermal Cells Reveals Distinct Division and Expansion Patterns for Pavement and Guard Cells1[W][OA

    Science.gov (United States)

    Asl, Leila Kheibarshekan; Dhondt, Stijn; Boudolf, Véronique; Beemster, Gerrit T.S.; Beeckman, Tom; Inzé, Dirk; Govaerts, Willy; De Veylder, Lieven

    2011-01-01

    To efficiently capture sunlight for photosynthesis, leaves typically develop into a flat and thin structure. This development is driven by cell division and expansion, but the individual contribution of these processes is currently unknown, mainly because of the experimental difficulties to disentangle them in a developing organ, due to their tight interconnection. To circumvent this problem, we built a mathematic model that describes the possible division patterns and expansion rates for individual epidermal cells. This model was used to fit experimental data on cell numbers and sizes obtained over time intervals of 1 d throughout the development of the first leaf pair of Arabidopsis (Arabidopsis thaliana). The parameters were obtained by a derivative-free optimization method that minimizes the differences between the predicted and experimentally observed cell size distributions. The model allowed us to calculate probabilities for a cell to divide into guard or pavement cells, the maximum size at which it can divide, and its average cell division and expansion rates at each point during the leaf developmental process. Surprisingly, average cell cycle duration remained constant throughout leaf development, whereas no evidence for a maximum cell size threshold for cell division of pavement cells was found. Furthermore, the model predicted that neighboring cells of different sizes within the epidermis expand at distinctly different relative rates, which could be verified by direct observations. We conclude that cell division seems to occur independently from the status of cell expansion, whereas the cell cycle might act as a timer rather than as a size-regulated machinery. PMID:21693673

  11. AtMMS21, an SMC5/6 complex subunit, is involved in stem cell niche maintenance and DNA damage responses in Arabidopsis roots.

    Science.gov (United States)

    Xu, Panglian; Yuan, Dongke; Liu, Ming; Li, Chunxin; Liu, Yiyang; Zhang, Shengchun; Yao, Nan; Yang, Chengwei

    2013-04-01

    Plants maintain stem cells in meristems to sustain lifelong growth; these stem cells must have effective DNA damage responses to prevent mutations that can propagate to large parts of the plant. However, the molecular links between stem cell functions and DNA damage responses remain largely unexplored. Here, we report that the small ubiquitin-related modifier E3 ligase AtMMS21 (for methyl methanesulfonate sensitivity gene21) acts to maintain the root stem cell niche by mediating DNA damage responses in Arabidopsis (Arabidopsis thaliana). Mutation of AtMMS21 causes defects in the root stem cell niche during embryogenesis and postembryonic stages. AtMMS21 is essential for the proper expression of stem cell niche-defining transcription factors. Moreover, mms21-1 mutants are hypersensitive to DNA-damaging agents, have a constitutively increased DNA damage response, and have more DNA double-strand breaks (DSBs) in the roots. Also, mms21-1 mutants exhibit spontaneous cell death within the root stem cell niche, and treatment with DSB-inducing agents increases this cell death, suggesting that AtMMS21 is required to prevent DSB-induced stem cell death. We further show that AtMMS21 functions as a subunit of the STRUCTURAL MAINTENANCE OF CHROMOSOMES5/6 complex, an evolutionarily conserved chromosomal ATPase required for DNA repair. These data reveal that AtMMS21 acts in DSB amelioration and stem cell niche maintenance during Arabidopsis root development.

  12. MAPK phosphatase AP2C3 induces ectopic proliferation of epidermal cells leading to stomata development in Arabidopsis.

    Directory of Open Access Journals (Sweden)

    Julija Umbrasaite

    2010-12-01

    Full Text Available In plant post-embryonic epidermis mitogen-activated protein kinase (MAPK signaling promotes differentiation of pavement cells and inhibits initiation of stomata. Stomata are cells specialized to modulate gas exchange and water loss. Arabidopsis MAPKs MPK3 and MPK6 are at the core of the signaling cascade; however, it is not well understood how the activity of these pleiotropic MAPKs is constrained spatially so that pavement cell differentiation is promoted only outside the stomata lineage. Here we identified a PP2C-type phosphatase termed AP2C3 (Arabidopsis protein phosphatase 2C that is expressed distinctively during stomata development as well as interacts and inactivates MPK3, MPK4 and MPK6. AP2C3 co-localizes with MAPKs within the nucleus and this localization depends on its N-terminal extension. We show that other closely related phosphatases AP2C2 and AP2C4 are also MAPK phosphatases acting on MPK6, but have a distinct expression pattern from AP2C3. In accordance with this, only AP2C3 ectopic expression is able to stimulate cell proliferation leading to excess stomata development. This function of AP2C3 relies on the domains required for MAPK docking and intracellular localization. Concomitantly, the constitutive and inducible AP2C3 expression deregulates E2F-RB pathway, promotes the abundance and activity of CDKA, as well as changes of CDKB1;1 forms. We suggest that AP2C3 downregulates the MAPK signaling activity to help maintain the balance between differentiation of stomata and pavement cells.

  13. Involvement of YODA and mitogen activated protein kinase 6 in Arabidopsis post-embryogenic root development through auxin up-regulation and cell division plane orientation

    Czech Academy of Sciences Publication Activity Database

    Smékalová, V.; Luptovčiak, I.; Komis, G.; Šamajová, O.; Ovečka, M.; Doskočilová, A.; Takáč, T.; Vadovič, P.; Novák, Ondřej; Pechan, T.; Ziemann, A.; Košútová, P.; Šamaj, J.

    2014-01-01

    Roč. 203, č. 4 (2014), s. 1175-1193 ISSN 0028-646X R&D Projects: GA MŠk(CZ) LO1204 Institutional support: RVO:61389030 Keywords : Arabidopsis * cell division plane * MAP65-1 Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 7.672, year: 2014

  14. A role for arabinogalactan-proteins in plant cell expansion: evidence from studies on the interaction of ß-glucosyl Yariv reagent with seedlings of Arabidopsis thaliana

    DEFF Research Database (Denmark)

    Willats, William George Tycho; Knox, J.P.

    1996-01-01

    Seedlings of Arabidopsis thaliana were germinated and grown in medium containing ß-glucosyl Yariv reagent (ßGlcY), a synthetic phenyl glycoside that interacts specifically with arabinogalactan-proteins (AGPs), a class of plant cell surface proteoglycans. The effect of ßGlcY on the seedlings...

  15. Early Effects of Altered Gravity Environments on Plant Cell Growth and Cell Proliferation: Characterization of Morphofunctional Nucleolar Types in an Arabidopsis Cell Culture System

    Energy Technology Data Exchange (ETDEWEB)

    Manzano, Ana I.; Herranz, Raúl; Manzano, Aránzazu [Centro de Investigaciones Biológicas (CSIC), Madrid (Spain); Loon, Jack J. W. A. van [Department of Oral and Maxillofacial Surgery/Oral Pathology, Dutch Experiment Support Center, VU University Medical Center, Amsterdam (Netherlands); Academic Centre for Dentistry Amsterdam (ACTA), Amsterdam (Netherlands); ESA-ESTEC, TEC-MMG, Noordwijk (Netherlands); Medina, F. Javier, E-mail: fjmedina@cib.csic.es [Centro de Investigaciones Biológicas (CSIC), Madrid (Spain)

    2016-02-05

    Changes in the cell growth rate of an in vitro cellular system in Arabidopsis thaliana induced by short exposure to an altered gravity environment have been estimated by a novel approach. The method consisted of defining three structural nucleolar types which are easy and reliable indicators of the ribosome biogenesis activity and, consequently, of protein biosynthesis, a parameter strictly correlated to cell growth in this cellular system. The relative abundance of each nucleolar type was statistically assessed in different conditions of gravity. Samples exposed to simulated microgravity for 200 min showed a significant decrease in nucleolar activity compared to 1g controls, whereas samples exposed to hypergravity (2g) for the same period showed nucleolar activity slightly increased. These effects could be considered as an early cellular response to the environmental alteration, given the short duration of the treatment. The functional significance of the structural data was validated by a combination of several different well-known parameters, using microscopical, flow cytometry, qPCR, and proteomic approaches, which showed that the decreased cell growth rate was decoupled from an increased cell proliferation rate under simulated microgravity, and the opposite trend was observed under hypergravity. Actually, not all parameters tested showed the same quantitative changes, indicating that the response to the environmental alteration is time-dependent. These results are in agreement with previous observations in root meristematic cells and they show the ability of plant cells to produce a response to gravity changes, independently of their integration into plant organs.

  16. NDR proteins: Lessons learned from Arabidopsis and animal cells prompt a testable hypothesis

    OpenAIRE

    Mudgil, Yashwanti; Jones, Alan M

    2010-01-01

    N-myc downregulated (NDR) genes were discovered more than fifteen years ago. Indirect evidence support a role in tumor progression and cellular differentiation, but their biochemical function is still unknown. Our detailed analyses on Arabidopsis NDR proteins (deisgnated NDR-like, NDL) show their involvement in altering auxin transport, local auxin gradients and expression level of auxin transport proteins. Animal NDL proteins may be involved in membrane recycling of E-cadherin and effector f...

  17. Protein profiling of single epidermal cell types from Arabidopsis thaliana using surface-enhanced laser desorption and ionization technology.

    Science.gov (United States)

    Ebert, Berit; Melle, Christian; Lieckfeldt, Elke; Zöller, Daniela; von Eggeling, Ferdinand; Fisahn, Joachim

    2008-08-25

    Here, we describe a novel approach for investigating differential protein expression within three epidermal cell types. In particular, 3000 single pavement, basal, and trichome cells from leaves of Arabidopsis thaliana were harvested by glass micro-capillaries. Subsequently, these single cell samples were joined to form pools of 100 individual cells and analyzed using the ProteinChip technology; SELDI: surface-enhanced laser desorption and ionization. As a result, numerous protein signals that were differentially expressed in the three epidermal cell types could be detected. One of these proteins was characterized by tryptical digestion and subsequent identification via tandem quadrupole-time of flight (Q-TOF) mass spectrometry. Down regulation of this sequenced small subunit precursor of ribulose-1,5 bisphosphate carboxylase(C) oxygenase(O) (RuBisCo) in trichome and basal cells indicates the sink status of these cell types that are located on the surface of A. thaliana source leaves. Based on the obtained protein profiles, we suggest a close functional relationship between basal and trichome cells at the protein level.

  18. iTRAQ Mitoproteome Analysis Reveals Mechanisms of Programmed Cell Death in Arabidopsis thaliana Induced by Ochratoxin A

    Directory of Open Access Journals (Sweden)

    Yan Wang

    2017-05-01

    Full Text Available Ochratoxin A (OTA is one of the most common and dangerous mycotoxins in the world. Previous work indicated that OTA could elicit spontaneous HR-like lesions formation Arabidopsis thaliana, reactive oxygen species (ROS play an important role in OTA toxicity, and their major endogenous source is mitochondria. However, there has been no evidence as to whether OTA induces directly PCD in plants until now. In this study, the presence of OTA in Arabidopsis thaliana leaves triggered accelerated respiration, increased production of mitochondrial ROS, the opening of ROS-dependent mitochondrial permeability transition pores and a decrease in mitochondrial membrane potential as well as the release of cytochrome c into the cytosol. There were 42 and 43 significantly differentially expressed proteins identified in response to exposure to OTA for 8 and 24 h, respectively, according to iTRAQ analysis. These proteins were mainly involved in perturbation of the mitochondrial electron transport chain, interfering with ATP synthesis and inducing PCD. Digital gene expression data at transcriptional level was consistent with the cell death induced by OTA being PCD. These results indicated that mitochondrial dysfunction was a prerequisite for OTA-induced PCD and the initiation and execution of PCD via a mitochondrial-mediated pathway.

  19. Cell wall accumulation of fluorescent proteins derived from a trans-Golgi cisternal membrane marker and paramural bodies in interdigitated Arabidopsis leaf epidermal cells.

    Science.gov (United States)

    Akita, Kae; Kobayashi, Megumi; Sato, Mayuko; Kutsuna, Natsumaro; Ueda, Takashi; Toyooka, Kiminori; Nagata, Noriko; Hasezawa, Seiichiro; Higaki, Takumi

    2017-01-01

    In most dicotyledonous plants, leaf epidermal pavement cells develop jigsaw puzzle-like shapes during cell expansion. The rapid growth and complicated cell shape of pavement cells is suggested to be achieved by targeted exocytosis that is coordinated with cytoskeletal rearrangement to provide plasma membrane and/or cell wall materials for lobe development during their morphogenesis. Therefore, visualization of membrane trafficking in leaf pavement cells should contribute an understanding of the mechanism of plant cell morphogenesis. To reveal membrane trafficking in pavement cells, we observed monomeric red fluorescent protein-tagged rat sialyl transferases, which are markers of trans-Golgi cisternal membranes, in the leaf epidermis of Arabidopsis thaliana. Quantitative fluorescence imaging techniques and immunoelectron microscopic observations revealed that accumulation of the red fluorescent protein occurred mostly in the curved regions of pavement cell borders and guard cell ends during leaf expansion. Transmission electron microscopy observations revealed that apoplastic vesicular membrane structures called paramural bodies were more frequent beneath the curved cell wall regions of interdigitated pavement cells and guard cell ends in young leaf epidermis. In addition, pharmacological studies showed that perturbations in membrane trafficking resulted in simple cell shapes. These results suggested possible heterogeneity of the curved regions of plasma membranes, implying a relationship with pavement cell morphogenesis.

  20. Sticking to cellulose: exploiting Arabidopsis seed coat mucilage to understand cellulose biosynthesis and cell wall polysaccharide interactions.

    Science.gov (United States)

    Griffiths, Jonathan S; North, Helen M

    2017-05-01

    The cell wall defines the shape of cells and ultimately plant architecture. It provides mechanical resistance to osmotic pressure while still being malleable and allowing cells to grow and divide. These properties are determined by the different components of the wall and the interactions between them. The major components of the cell wall are the polysaccharides cellulose, hemicellulose and pectin. Cellulose biosynthesis has been extensively studied in Arabidopsis hypocotyls, and more recently in the mucilage-producing epidermal cells of the seed coat. The latter has emerged as an excellent system to study cellulose biosynthesis and the interactions between cellulose and other cell wall polymers. Here we review some of the major advances in our understanding of cellulose biosynthesis in the seed coat, and how mucilage has aided our understanding of the interactions between cellulose and other cell wall components required for wall cohesion. Recently, 10 genes involved in cellulose or hemicellulose biosynthesis in mucilage have been identified. These discoveries have helped to demonstrate that xylan side-chains on rhamnogalacturonan I act to link this pectin directly to cellulose. We also examine other factors that, either directly or indirectly, influence cellulose organization or crystallization in mucilage. © 2017 INRA. New Phytologist © 2017 New Phytologist Trust.

  1. Control of DEMETER DNA demethylase gene transcription in male and female gamete companion cells in Arabidopsis thaliana.

    Science.gov (United States)

    Park, Jin-Sup; Frost, Jennifer M; Park, Kyunghyuk; Ohr, Hyonhwa; Park, Guen Tae; Kim, Seohyun; Eom, Hyunjoo; Lee, Ilha; Brooks, Janie S; Fischer, Robert L; Choi, Yeonhee

    2017-02-21

    The DEMETER (DME) DNA glycosylase initiates active DNA demethylation via the base-excision repair pathway and is vital for reproduction in Arabidopsis thaliana DME-mediated DNA demethylation is preferentially targeted to small, AT-rich, and nucleosome-depleted euchromatic transposable elements, influencing expression of adjacent genes and leading to imprinting in the endosperm. In the female gametophyte, DME expression and subsequent genome-wide DNA demethylation are confined to the companion cell of the egg, the central cell. Here, we show that, in the male gametophyte, DME expression is limited to the companion cell of sperm, the vegetative cell, and to a narrow window of time: immediately after separation of the companion cell lineage from the germline. We define transcriptional regulatory elements of DME using reporter genes, showing that a small region, which surprisingly lies within the DME gene, controls its expression in male and female companion cells. DME expression from this minimal promoter is sufficient to rescue seed abortion and the aberrant DNA methylome associated with the null dme-2 mutation. Within this minimal promoter, we found short, conserved enhancer sequences necessary for the transcriptional activities of DME and combined predicted binding motifs with published transcription factor binding coordinates to produce a list of candidate upstream pathway members in the genetic circuitry controlling DNA demethylation in gamete companion cells. These data show how DNA demethylation is regulated to facilitate endosperm gene imprinting and potential transgenerational epigenetic regulation, without subjecting the germline to potentially deleterious transposable element demethylation.

  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. The cell wall-localized atypical β-1,3 glucanase ZERZAUST controls tissue morphogenesis in Arabidopsis thaliana.

    Science.gov (United States)

    Vaddepalli, Prasad; Fulton, Lynette; Wieland, Jennifer; Wassmer, Katrin; Schaeffer, Milena; Ranf, Stefanie; Schneitz, Kay

    2017-06-15

    Orchestration of cellular behavior in plant organogenesis requires integration of intercellular communication and cell wall dynamics. The underlying signaling mechanisms are poorly understood. Tissue morphogenesis in Arabidopsis depends on the receptor-like kinase STRUBBELIG. Mutations in ZERZAUST were previously shown to result in a strubbelig -like mutant phenotype. Here, we report on the molecular identification and functional characterization of ZERZAUST We show that ZERZAUST encodes a putative GPI-anchored β-1,3 glucanase suggested to degrade the cell wall polymer callose. However, a combination of in vitro , cell biological and genetic experiments indicate that ZERZAUST is not involved in the regulation of callose accumulation. Nonetheless, Fourier-transformed infrared-spectroscopy revealed that zerzaust mutants show defects in cell wall composition. Furthermore, the results indicate that ZERZAUST represents a mobile apoplastic protein, and that its carbohydrate-binding module family 43 domain is required for proper subcellular localization and function whereas its GPI anchor is dispensable. Our collective data reveal that the atypical β-1,3 glucanase ZERZAUST acts in a non-cell-autonomous manner and is required for cell wall organization during tissue morphogenesis. © 2017. Published by The Company of Biologists Ltd.

  4. Null mutants of individual RABA genes impact the proportion of different cell wall components in stem tissue of Arabidopsis thaliana.

    Directory of Open Access Journals (Sweden)

    Daniel Lunn

    Full Text Available In Arabidopsis, and other plants, the RABA GTPases (orthologous to the Rab11a of mammals have expanded in number and diversity and have been shown to belong to eight sub clades, some of which have been implicated in controlling vesicles that traffic cell wall polymers and enzymes that synthesise or modify them to the cell wall. In order to investigate this, we have investigated whether T-DNA insertion knockouts of individual RABA genes belonging to different sub clades, impact on the composition of the plant cell wall. Single gene knockouts of the RABA1, RABA2 and RABA4 sub clades primarily affected the percentage composition of pectin, cellulose and hemicellulose within the cell wall, respectively, despite having no obvious phenotype in the whole plant. We hypothesise that vesicles carrying specific types of cargoes from the Golgi to the cell surface may be regulated by particular sub types of RABA proteins, a finding that could have wider implications for how trafficking systems work and could be a useful tool in cell wall research and other fields of plant biology.

  5. NDR proteins: lessons learned from Arabidopsis and animal cells prompt a testable hypothesis.

    Science.gov (United States)

    Mudgil, Yashwanti; Jones, Alan M

    2010-08-01

    N-myc Down Regulated (NDR) genes were discovered more than fifteen years ago. Indirect evidence support a role in tumor progression and cellular differentiation, but their biochemical function is still unknown. Our detailed analyses on Arabidopsis NDL proteins show their involvement in altering auxin transport, local auxin gradients and expression level of auxin transport proteins. Animal NDL proteins may be involved in membrane recycling of E-cadherin and effector for the small GTPase. In light of these findings, we hypothesize that NDL proteins regulate vesicular trafficking of auxin transport facilitator PIN proteins by biochemically alterating the local lipid environment of PIN proteins.

  6. Salicylic acid modulates levels of phosphoinositide dependent-phospholipase C substrates and products to remodel the Arabidopsis suspension cell transcriptome

    Directory of Open Access Journals (Sweden)

    Eric eRuelland

    2014-11-01

    Full Text Available Basal phosphoinositide-dependent phospholipase C (PI-PLC activity controls gene expression in Arabidopsis suspension cells and seedlings. PI-PLC catalyzes the production of phosphorylated inositol and diacylglycerol (DAG from phosphoinositides. It is not known how PI-PLC regulates the transcriptome although the action of DAG-kinase (DGK on DAG immediately downstream from PI-PLC is responsible for some of the regulation. We previously established a list of genes whose expression is affected in the presence of PI-PLC inhibitors. Here this list of genes was used as a signature in similarity searches of curated plant hormone response transcriptome data. The strongest correlations obtained with the inhibited PI-PLC signature were with salicylic acid (SA treatments. We confirm here that in Arabidopsis suspension cells SA treatment leads to an increase in phosphoinositides, then demonstrate that SA leads to a significant 20% decrease in phosphatidic acid, indicative of a decrease in PI-PLC products. Previous sets of microarray data were re-assessed. The SA response of one set of genes was dependent on phosphoinositides. Alterations in the levels of a second set of genes, mostly SA-repressed genes, could be related to decreases in PI-PLC products that occur in response to SA action. Together, the two groups of genes comprise at least 40% of all SA-responsive genes. Overall these two groups of genes are distinct in the functional categories of the proteins they encode, their promoter cis-elements and their regulation by DGK or phospholipase D. SA-regulated genes dependent on phosphoinositides are typical SA response genes while those with an SA response that is possibly dependent on PI-PLC products are less SA-specific. We propose a model in which SA inhibits PI-PLC activity and alters levels of PI-PLC products and substrates, thereby regulating gene expression divergently.

  7. Arabidopsis homolog of trithorax1 (ATX1) is required for cell production, patterning, and morphogenesis in root development.

    Science.gov (United States)

    Napsucialy-Mendivil, Selene; Alvarez-Venegas, Raúl; Shishkova, Svetlana; Dubrovsky, Joseph G

    2014-12-01

    Arabidopsis homolog of trithorax1 (ATX1/SDG27), a known regulator of flower development, encodes a H3K4histone methyltransferase that maintains a number of genes in an active state. In this study, the role of ATX1 in root development was evaluated. The loss-of-function mutant atx1-1 was impaired in primary root growth. The data suggest that ATX1 controls root growth by regulating cell cycle duration, cell production, and the transition from cell proliferation in the root apical meristem (RAM) to cell elongation. In atx1-1, the quiescent centre (QC) cells were irregular in shape and more expanded than those of the wild type. This feature, together with the atypical distribution of T-divisions, the presence of oblique divisions, and the abnormal cell patterning in the RAM, suggests a lack of coordination between cell division and cell growth in the mutant. The expression domain of QC-specific markers was expanded both in the primary RAM and in the developing lateral root primordia of atx1-1 plants. These abnormalities were independent of auxin-response gradients. ATX1 was also found to be required for lateral root initiation, morphogenesis, and emergence. The time from lateral root initiation to emergence was significantly extended in the atx1-1 mutant. Overall, these data suggest that ATX1 is involved in the timing of root development, stem cell niche maintenance, and cell patterning during primary and lateral root development. Thus, ATX1 emerges as an important player in root system architecture. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  8. Continuous-time modeling of cell fate determination in Arabidopsis flowers

    Directory of Open Access Journals (Sweden)

    Angenent Gerco C

    2010-07-01

    Full Text Available Abstract Background The genetic control of floral organ specification is currently being investigated by various approaches, both experimentally and through modeling. Models and simulations have mostly involved boolean or related methods, and so far a quantitative, continuous-time approach has not been explored. Results We propose an ordinary differential equation (ODE model that describes the gene expression dynamics of a gene regulatory network that controls floral organ formation in the model plant Arabidopsis thaliana. In this model, the dimerization of MADS-box transcription factors is incorporated explicitly. The unknown parameters are estimated from (known experimental expression data. The model is validated by simulation studies of known mutant plants. Conclusions The proposed model gives realistic predictions with respect to independent mutation data. A simulation study is carried out to predict the effects of a new type of mutation that has so far not been made in Arabidopsis, but that could be used as a severe test of the validity of the model. According to our predictions, the role of dimers is surprisingly important. Moreover, the functional loss of any dimer leads to one or more phenotypic alterations.

  9. Transient gibberellin application promotes Arabidopsis thaliana hypocotyl cell elongation without maintaining transverse orientation of microtubules on the outer tangential wall of epidermal cells

    KAUST Repository

    Sauret-Güeto, Susanna

    2011-11-25

    The phytohormone gibberellin (GA) promotes plant growth by stimulating cellular expansion. Whilst it is known that GA acts by opposing the growth-repressing effects of DELLA proteins, it is not known how these events promote cellular expansion. Here we present a time-lapse analysis of the effects of a single pulse of GA on the growth of Arabidopsis hypocotyls. Our analyses permit kinetic resolution of the transient growth effects of GA on expanding cells. We show that pulsed application of GA to the relatively slowly growing cells of the unexpanded light-grown Arabidopsis hypocotyl results in a transient burst of anisotropic cellular growth. This burst, and the subsequent restoration of initial cellular elongation rates, occurred respectively following the degradation and subsequent reappearance of a GFP-tagged DELLA (GFP-RGA). In addition, we used a GFP-tagged α-tubulin 6 (GFP-TUA6) to visualise the behaviour of microtubules (MTs) on the outer tangential wall (OTW) of epidermal cells. In contrast to some current hypotheses concerning the effect of GA on MTs, we show that the GA-induced boost of hypocotyl cell elongation rate is not dependent upon the maintenance of transverse orientation of the OTW MTs. This confirms that transverse alignment of outer face MTs is not necessary to maintain rapid elongation rates of light-grown hypocotyls. Together with future studies on MT dynamics in other faces of epidermal cells and in cells deeper within the hypocotyl, our observations advance understanding of the mechanisms by which GA promotes plant cell and organ growth. © 2011 Blackwell Publishing Ltd.

  10. α-Xylosidase plays essential roles in xyloglucan remodelling, maintenance of cell wall integrity, and seed germination in Arabidopsis thaliana.

    Science.gov (United States)

    Shigeyama, Takuma; Watanabe, Asuka; Tokuchi, Konatsu; Toh, Shigeo; Sakurai, Naoki; Shibuya, Naoto; Kawakami, Naoto

    2016-10-01

    Regulation and maintenance of cell wall physical properties are crucial for plant growth and environmental response. In the germination process, hypocotyl cell expansion and endosperm weakening are prerequisites for dicot seeds to complete germination. We have identified the Arabidopsis mutant thermoinhibition-resistant germination 1 (trg1), which has reduced seed dormancy and insensitivity to unfavourable conditions for germination owing to a loss-of-function mutation of TRG1/XYL1, which encodes an α-xylosidase. Compared to those of wild type, the elongating stem of trg1 showed significantly lower viscoelasticity, and the fruit epidermal cells were longitudinally shorter and horizontally enlarged. Actively growing tissues of trg1 over-accumulated free xyloglucan oligosaccharides (XGOs), and the seed cell wall had xyloglucan with a greatly reduced molecular weight. These observations suggest that XGOs reduce xyloglucan size by serving as an acceptor in transglycosylation and eventually enhancing cell wall loosening. TRG1/XYL1 gene expression was abundant in growing wild-type organs and tissues but relatively low in cells at most actively elongating part of the tissues, suggesting that α-xylosidase contributes to maintaining the mechanical integrity of the primary cell wall in the growing and pre-growing tissues. In germinating seeds of trg1, expression of genes encoding specific abscisic acid and gibberellin metabolism enzymes was altered in accordance with the aberrant germination phenotype. Thus, cell wall integrity could affect seed germination not only directly through the physical properties of the cell wall but also indirectly through the regulation of hormone gene expression. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  11. TONNEAU2/FASS Regulates the Geometry of Microtubule Nucleation and Cortical Array Organization in Interphase Arabidopsis Cells[C][W

    Science.gov (United States)

    Kirik, Angela; Ehrhardt, David W.; Kirik, Viktor

    2012-01-01

    Organization of microtubules into ordered arrays involves spatial and temporal regulation of microtubule nucleation. Here, we show that acentrosomal microtubule nucleation in plant cells involves a previously unknown regulatory step that determines the geometry of microtubule nucleation. Dynamic imaging of interphase cortical microtubules revealed that the ratio of branching to in-bundle microtubule nucleation on cortical microtubules is regulated by the Arabidopsis thaliana B′′ subunit of protein phosphatase 2A, which is encoded by the TONNEAU2/FASS (TON2) gene. The probability of nucleation from γ-tubulin complexes localized at the cell cortex was not affected by a loss of TON2 function, suggesting a specific role of TON2 in regulating the nucleation geometry. Both loss of TON2 function and ectopic targeting of TON2 to the plasma membrane resulted in defects in cell shape, suggesting the importance of TON2-mediated regulation of the microtubule cytoskeleton in cell morphogenesis. Loss of TON2 function also resulted in an inability for cortical arrays to reorient in response to light stimulus, suggesting an essential role for TON2 and microtubule branching nucleation in reorganization of microtubule arrays. Our data establish TON2 as a regulator of interphase microtubule nucleation and provide experimental evidence for a novel regulatory step in the process of microtubule-dependent nucleation. PMID:22395485

  12. KIRA1 and ORESARA1 terminate flower receptivity by promoting cell death in the stigma of Arabidopsis.

    Science.gov (United States)

    Gao, Zhen; Daneva, Anna; Salanenka, Yuliya; Van Durme, Matthias; Huysmans, Marlies; Lin, Zongcheng; De Winter, Freya; Vanneste, Steffen; Karimi, Mansour; Van de Velde, Jan; Vandepoele, Klaas; Van de Walle, Davy; Dewettinck, Koen; Lambrecht, Bart N; Nowack, Moritz K

    2018-05-28

    Flowers have a species-specific functional life span that determines the time window in which pollination, fertilization and seed set can occur. The stigma tissue plays a key role in flower receptivity by intercepting pollen and initiating pollen tube growth toward the ovary. In this article, we show that a developmentally controlled cell death programme terminates the functional life span of stigma cells in Arabidopsis. We identified the leaf senescence regulator ORESARA1 (also known as ANAC092) and the previously uncharacterized KIRA1 (also known as ANAC074) as partially redundant transcription factors that modulate stigma longevity by controlling the expression of programmed cell death-associated genes. KIRA1 expression is sufficient to induce cell death and terminate floral receptivity, whereas lack of both KIRA1 and ORESARA1 substantially increases stigma life span. Surprisingly, the extension of stigma longevity is accompanied by only a moderate extension of flower receptivity, suggesting that additional processes participate in the control of the flower's receptive life span.

  13. MUM ENHANCERS are important for seed coat mucilage production and mucilage secretory cell differentiation in Arabidopsis thaliana.

    Science.gov (United States)

    Arsovski, Andrej A; Villota, Maria M; Rowland, Owen; Subramaniam, Rajagopal; Western, Tamara L

    2009-01-01

    Pollination triggers not only embryo development but also the differentiation of the ovule integuments to form a specialized seed coat. The mucilage secretory cells of the Arabidopsis thaliana seed coat undergo a complex differentiation process in which cell growth is followed by the synthesis and secretion of pectinaceous mucilage. A number of genes have been identified affecting mucilage secretory cell differentiation, including MUCILAGE-MODIFIED4 (MUM4). mum4 mutants produce a reduced amount of mucilage and cloning of MUM4 revealed that it encodes a UDP-L-rhamnose synthase that is developmentally up-regulated to provide rhamnose for mucilage pectin synthesis. To identify additional genes acting in mucilage synthesis and secretion, a screen for enhancers of the mum4 phenotype was performed. Eight mum enhancers (men) have been identified, two of which result from defects in known mucilage secretory cell genes (MUM2 and MYB61). Our results show that, in a mum4 background, mutations in MEN1, MEN4, and MEN5 lead to further reductions in mucilage compared to mum4 single mutants, suggesting that they are involved in mucilage synthesis or secretion. Conversely, mutations in MEN2 and MEN6 appear to affect mucilage release rather than quantity. With the exception of men4, whose single mutant exhibits reduced mucilage, none of these genes have a single mutant phenotype, suggesting that they would not have been identified outside the compromised mum4 background.

  14. A multidirectional non-cell autonomous control and a genetic interaction restricting tobacco etch virus susceptibility in Arabidopsis.

    Directory of Open Access Journals (Sweden)

    Suresh Gopalan

    2007-10-01

    Full Text Available Viruses constitute a major class of pathogens that infect a variety of hosts. Understanding the intricacies of signaling during host-virus interactions should aid in designing disease prevention strategies and in understanding mechanistic aspects of host and pathogen signaling machinery.An Arabidopsis mutant, B149, impaired in susceptibility to Tobacco etch virus (TEV, a positive strand RNA virus of picoRNA family, was identified using a high-throughput genetic screen and a counterselection scheme. The defects include initiation of infection foci, rate of cell-to-cell movement and long distance movement.The defect in infectivity is conferred by a recessive locus. Molecular genetic analysis and complementation analysis with three alleles of a previously published mutant lsp1 (loss of susceptibility to potyviruses indicate a genetic interaction conferring haploinsufficiency between the B149 locus and certain alleles of lsp1 resulting in impaired host susceptibility. The pattern of restriction of TEV foci on leaves at or near the boundaries of certain cell types and leaf boundaries suggest dysregulation of a multidirectional non-cell autonomous regulatory mechanism. Understanding the nature of this multidirectional signal and the molecular genetic mechanism conferring it should potentially reveal a novel arsenal in the cellular machinery.

  15. Statolith sedimentation kinetics and force transduction to the cortical endoplasmic reticulum in gravity-sensing Arabidopsis columella cells.

    Science.gov (United States)

    Leitz, Guenther; Kang, Byung-Ho; Schoenwaelder, Monica E A; Staehelin, L Andrew

    2009-03-01

    The starch statolith hypothesis of gravity sensing in plants postulates that the sedimentation of statoliths in specialized statocytes (columella cells) provides the means for converting the gravitational potential energy into a biochemical signal. We have analyzed the sedimentation kinetics of statoliths in the central S2 columella cells of Arabidopsis thaliana. The statoliths can form compact aggregates with gap sizes between statoliths approaching sedimentation phase, the statoliths tend to move at a distance to the cortical endoplasmic reticulum (ER) boundary and interact only transiently with the ER. Statoliths moved by laser tweezers against the ER boundary experience an elastic lift force upon release from the optical trap. High-resolution electron tomography analysis of statolith-to-ER contact sites indicate that the weight of statoliths is sufficient to locally deform the ER membranes that can potentially activate mechanosensitive ion channels. We suggest that in root columella cells, the transduction of the kinetic energy of sedimenting statoliths into a biochemical signal involves a combination of statolith-driven motion of the cytosol, statolith-induced deformation of the ER membranes, and a rapid release of kinetic energy from the ER during reorientation to activate mechanosensitive sites within the central columella cells.

  16. Microarray Expression Analyses of Arabidopsis Guard Cells and Isolation of a Recessive Abscisic Acid Hypersensitive Protein Phosphatase 2C MutantW⃞

    Science.gov (United States)

    Leonhardt, Nathalie; Kwak, June M.; Robert, Nadia; Waner, David; Leonhardt, Guillaume; Schroeder, Julian I.

    2004-01-01

    Oligomer-based DNA Affymetrix GeneChips representing about one-third of Arabidopsis (Arabidopsis thaliana) genes were used to profile global gene expression in a single cell type, guard cells, identifying 1309 guard cell–expressed genes. Highly pure preparations of guard cells and mesophyll cells were isolated in the presence of transcription inhibitors that prevented induction of stress-inducible genes during cell isolation procedures. Guard cell expression profiles were compared with those of mesophyll cells, resulting in identification of 64 transcripts expressed preferentially in guard cells. Many large gene families and gene duplications are known to exist in the Arabidopsis genome, giving rise to redundancies that greatly hamper conventional genetic and functional genomic analyses. The presented genomic scale analysis identifies redundant expression of specific isoforms belonging to large gene families at the single cell level, which provides a powerful tool for functional genomic characterization of the many signaling pathways that function in guard cells. Reverse transcription–PCR of 29 genes confirmed the reliability of GeneChip results. Statistical analyses of promoter regions of abscisic acid (ABA)–regulated genes reveal an overrepresented ABA responsive motif, which is the known ABA response element. Interestingly, expression profiling reveals ABA modulation of many known guard cell ABA signaling components at the transcript level. We further identified a highly ABA-induced protein phosphatase 2C transcript, AtP2C-HA, in guard cells. A T-DNA disruption mutation in AtP2C-HA confers ABA-hypersensitive regulation of stomatal closing and seed germination. The presented data provide a basis for cell type–specific genomic scale analyses of gene function. PMID:14973164

  17. Building bridges: formin1 of Arabidopsis forms a connection between the cell wall and the actin cytoskeleton.

    Science.gov (United States)

    Martinière, Alexandre; Gayral, Philippe; Hawes, Chris; Runions, John

    2011-04-01

    Actin microfilament (MF) organization and remodelling is critical to cell function. The formin family of actin binding proteins are involved in nucleating MFs in Arabidopsis thaliana. They all contain formin homology domains in the intracellular, C-terminal half of the protein that interacts with MFs. Formins in class I are usually targeted to the plasma membrane and this is true of Formin1 (AtFH1) of A. thaliana. In this study, we have investigated the extracellular domain of AtFH1 and we demonstrate that AtFH1 forms a bridge from the actin cytoskeleton, across the plasma membrane and is anchored within the cell wall. AtFH1 has a large, extracellular domain that is maintained by purifying selection and that contains four conserved regions, one of which is responsible for immobilising the protein. Protein anchoring within the cell wall is reduced in constructs that express truncations of the extracellular domain and in experiments in protoplasts without primary cell walls. The 18 amino acid proline-rich extracellular domain that is responsible for AtFH1 anchoring has homology with cell-wall extensins. We also have shown that anchoring of AtFH1 in the cell wall promotes actin bundling within the cell and that overexpression of AtFH1 has an inhibitory effect on organelle actin-dependant dynamics. Thus, the AtFH1 bridge provides stable anchor points for the actin cytoskeleton and is probably a crucial component of the signalling response and actin-remodelling mechanisms. © 2011 The Authors. The Plant Journal © 2011 Blackwell Publishing Ltd.

  18. Atomic force microscopy stiffness tomography on living Arabidopsis thaliana cells reveals the mechanical properties of surface and deep cell-wall layers during growth.

    Science.gov (United States)

    Radotić, Ksenija; Roduit, Charles; Simonović, Jasna; Hornitschek, Patricia; Fankhauser, Christian; Mutavdžić, Dragosav; Steinbach, Gabor; Dietler, Giovanni; Kasas, Sandor

    2012-08-08

    Cell-wall mechanical properties play a key role in the growth and the protection of plants. However, little is known about genuine wall mechanical properties and their growth-related dynamics at subcellular resolution and in living cells. Here, we used atomic force microscopy (AFM) stiffness tomography to explore stiffness distribution in the cell wall of suspension-cultured Arabidopsis thaliana as a model of primary, growing cell wall. For the first time that we know of, this new imaging technique was performed on living single cells of a higher plant, permitting monitoring of the stiffness distribution in cell-wall layers as a function of the depth and its evolution during the different growth phases. The mechanical measurements were correlated with changes in the composition of the cell wall, which were revealed by Fourier-transform infrared (FTIR) spectroscopy. In the beginning and end of cell growth, the average stiffness of the cell wall was low and the wall was mechanically homogenous, whereas in the exponential growth phase, the average wall stiffness increased, with increasing heterogeneity. In this phase, the difference between the superficial and deep wall stiffness was highest. FTIR spectra revealed a relative increase in the polysaccharide/lignin content. Copyright © 2012 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  19. Changes in Gene Expression of Arabidopsis Thaliana Cell Cultures Upon Exposure to Real and Simulated Partial- g Forces

    Science.gov (United States)

    Fengler, Svenja; Spirer, Ina; Neef, Maren; Ecke, Margret; Hauslage, Jens; Hampp, Rüdiger

    2016-06-01

    Cell cultures of the plant model organism Arabidopsis thaliana were exposed to partial- g forces during parabolic flight and clinostat experiments (0.16 g, 0.38 g and 0.5 g were tested). In order to investigate gravity-dependent alterations in gene expression, samples were metabolically quenched by the fixative RNA later Ⓡ to stabilize nucleic acids and used for whole-genome microarray analysis. An attempt to identify the potential threshold acceleration for the gravity-dependent response showed that the smaller the experienced g-force, the greater was the susceptibility of the cell cultures. Compared to short-term μ g during a parabolic flight, the number of differentially expressed genes under partial- g was lower. In addition, the effect on the alteration of amounts of transcripts decreased during partial- g parabolic flight due to the sequence of the different parabolas (0.38 g, 0.16 g and μ g). A time-dependent analysis under simulated 0.5 g indicates that adaptation occurs within minutes. Differentially expressed genes (at least 2-fold up- or down-regulated in expression) under real flight conditions were to some extent identical with those affected by clinorotation. The highest number of homologuous genes was detected within seconds of exposure to 0.38 g (both flight and clinorotation). To a considerable part, these genes deal with cell wall properties. Additionally, responses specific for clinorotation were observed.

  20. The cysteine protease CEP1, a key executor involved in tapetal programmed cell death, regulates pollen development in Arabidopsis.

    Science.gov (United States)

    Zhang, Dandan; Liu, Di; Lv, Xiaomeng; Wang, Ying; Xun, Zhili; Liu, Zhixiong; Li, Fenglan; Lu, Hai

    2014-07-01

    Tapetal programmed cell death (PCD) is a prerequisite for pollen grain development in angiosperms, and cysteine proteases are the most ubiquitous hydrolases involved in plant PCD. We identified a papain-like cysteine protease, CEP1, which is involved in tapetal PCD and pollen development in Arabidopsis thaliana. CEP1 is expressed specifically in the tapetum from stages 5 to 11 of anther development. The CEP1 protein first appears as a proenzyme in precursor protease vesicles and is then transported to the vacuole and transformed into the mature enzyme before rupture of the vacuole. cep1 mutants exhibited aborted tapetal PCD and decreased pollen fertility with abnormal pollen exine. A transcriptomic analysis revealed that 872 genes showed significantly altered expression in the cep1 mutants, and most of them are important for tapetal cell wall organization, tapetal secretory structure formation, and pollen development. CEP1 overexpression caused premature tapetal PCD and pollen infertility. ELISA and quantitative RT-PCR analyses confirmed that the CEP1 expression level showed a strong relationship to the degree of tapetal PCD and pollen fertility. Our results reveal that CEP1 is a crucial executor during tapetal PCD and that proper CEP1 expression is necessary for timely degeneration of tapetal cells and functional pollen formation. © 2014 American Society of Plant Biologists. All rights reserved.

  1. Simulation of Fungal-Mediated Cell Death by Fumonisin B1 and Selection of Fumonisin B1–Resistant (fbr) Arabidopsis Mutants

    Science.gov (United States)

    Stone, Julie M.; Heard, Jacqueline E.; Asai, Tsuneaki; Ausubel, Frederick M.

    2000-01-01

    Fumonisin B1 (FB1), a programmed cell death–eliciting toxin produced by the necrotrophic fungal plant pathogen Fusarium moniliforme, was used to simulate pathogen infection in Arabidopsis. Plants infiltrated with 10 μM FB1 and seedlings transferred to agar media containing 1 μM FB1 develop lesions reminiscent of the hypersensitive response, including generation of reactive oxygen intermediates, deposition of phenolic compounds and callose, accumulation of phytoalexin, and expression of pathogenesis-related (PR) genes. Arabidopsis FB1-resistant (fbr) mutants were selected directly by sowing seeds on agar containing 1 μM FB1, on which wild-type seedlings fail to develop. Two mutants chosen for further analyses, fbr1 and fbr2, had altered PR gene expression in response to FB1. fbr1 and fbr2 do not exhibit differential resistance to the avirulent bacterial pathogen Pseudomonas syringae pv maculicola (ES4326) expressing the avirulence gene avrRpt2 but do display enhanced resistance to a virulent isogenic strain that lacks the avirulence gene. Our results demonstrate the utility of FB1 for high-throughput isolation of Arabidopsis defense-related mutants and suggest that pathogen-elicited programmed cell death of host cells may be an important feature of compatible plant–pathogen interactions. PMID:11041878

  2. Chloroplast Dysfunction Causes Multiple Defects in Cell Cycle Progression in the Arabidopsis crumpled leaf Mutant

    KAUST Repository

    Hudik, Elodie; Yoshioka, Yasushi; Domenichini, Sé Verine; Bourge, Mickaë l; Soubigout-Taconnat, Ludivine; Mazubert, Christelle; Yi, Dalong; Bujaldon, Sandrine; Hayashi, Hiroyuki; De Veylder, Lieven; Bergounioux, Catherine; Benhamed, Moussa; Raynaud, Cé cile

    2014-01-01

    The majority of research on cell cycle regulation is focused on the nuclear events that govern the replication and segregation of the genome between the two daughter cells. However, eukaryotic cells contain several compartmentalized organelles

  3. Restricted cell elongation in Arabidopsis hypocotyls is associated with a reduced average pectin esterification level

    OpenAIRE

    Derbyshire, Paul; McCann, Maureen C; Roberts, Keith

    2007-01-01

    Abstract Background Cell elongation is mainly limited by the extensibility of the cell wall. Dicotyledonous primary (growing) cell walls contain cellulose, xyloglucan, pectin and proteins, but little is known about how each polymer class contributes to the cell wall mechanical properties that control extensibility. Results We present evidence that the degree of pectin methyl-esterification (DE%) limits cell growth, and that a minimum level of about 60% DE is required for normal cell elongatio...

  4. ARP2/3 localization in Arabidopsis leaf pavement cells: a diversity of intracellular pools and cytoskeletal interactions.

    Science.gov (United States)

    Zhang, Chunhua; Mallery, Eileen L; Szymanski, Daniel B

    2013-01-01

    In plant cells the actin cytoskeleton adopts many configurations, but is best understood as an unstable, interconnected track that rearranges to define the patterns of long distance transport of organelles during growth. Actin filaments do not form spontaneously; instead filament nucleators, such as the evolutionarily conserved actin-related protein (ARP) 2/3 complex, can efficiently generate new actin filament networks when in a fully activated state. A growing number of genetic experiments have shown that ARP2/3 is necessary for morphogenesis in processes that range from tip growth during root nodule formation to the diffuse polarized growth of leaf trichomes and pavement cells. Although progress has been rapid in the identification of proteins that function in series to positively regulate ARP2/3, less has been learned about the actual function of ARP2/3 in cells. In this paper, we analyze the localization of ARP2/3 in Arabidopsis leaf pavement cells. We detect a pool of ARP2/3 in the nucleus, and also find that ARP2/3 is efficiently and specifically clustered on multiple organelle surfaces and associates with both the actin filament and microtubule cytoskeletons. Our mutant analyses and ARP2/3 and actin double labeling experiments indicate that the clustering of ARP2/3 on organelle surfaces and an association with actin bundles does not necessarily reflect an active pool of ARP2/3, and instead most of the complex appears to exist as a latent organelle-associated pool.

  5. Efficient Plastid Transformation in Arabidopsis.

    Science.gov (United States)

    Yu, Qiguo; Lutz, Kerry Ann; Maliga, Pal

    2017-09-01

    Plastid transformation is routine in tobacco ( Nicotiana tabacum ) but 100-fold less frequent in Arabidopsis ( Arabidopsis thaliana ), preventing its use in plastid biology. A recent study revealed that null mutations in ACC2 , encoding a plastid-targeted acetyl-coenzyme A carboxylase, cause hypersensitivity to spectinomycin. We hypothesized that plastid transformation efficiency should increase in the acc2 background, because when ACC2 is absent, fatty acid biosynthesis becomes dependent on translation of the plastid-encoded ACC β-carboxylase subunit. We bombarded ACC2 -defective Arabidopsis leaves with a vector carrying a selectable spectinomycin resistance ( aadA ) gene and gfp , encoding the green fluorescence protein GFP. Spectinomycin-resistant clones were identified as green cell clusters on a spectinomycin medium. Plastid transformation was confirmed by GFP accumulation from the second open reading frame of a polycistronic messenger RNA, which would not be translated in the cytoplasm. We obtained one to two plastid transformation events per bombarded sample in spectinomycin-hypersensitive Slavice and Columbia acc2 knockout backgrounds, an approximately 100-fold enhanced plastid transformation frequency. Slavice and Columbia are accessions in which plant regeneration is uncharacterized or difficult to obtain. A practical system for Arabidopsis plastid transformation will be obtained by creating an ACC2 null background in a regenerable Arabidopsis accession. The recognition that the duplicated ACCase in Arabidopsis is an impediment to plastid transformation provides a rational template to implement plastid transformation in related recalcitrant crops. © 2017 American Society of Plant Biologists. All Rights Reserved.

  6. Does Ploidy Level Directly Control Cell Size? Counterevidence from Arabidopsis Genetics

    OpenAIRE

    Tsukaya, Hirokazu

    2013-01-01

    Ploidy level affects cell size in many organisms, and ploidy-dependent cell enlargement has been used to breed many useful organisms. However, how polyploidy affects cell size remains unknown. Previous studies have explored changes in transcriptome data caused by polyploidy, but have not been successful. The most naïve theory explaining ploidy-dependent cell enlargement is that increases in gene copy number increase the amount of protein, which in turn increases the cell volume. This hypothes...

  7. Interacting signal pathways control defense gene expression in Arabidopsis in response to cell wall-degrading enzymes from Erwinia carotovora.

    Science.gov (United States)

    Norman-Setterblad, C; Vidal, S; Palva, E T

    2000-04-01

    We have characterized the role of salicylic acid (SA)-independent defense signaling in Arabidopsis thaliana in response to the plant pathogen Erwinia carotovora subsp. carotovora. Use of pathway-specific target genes as well as signal mutants allowed us to elucidate the role and interactions of ethylene, jasmonic acid (JA), and SA signal pathways in this response. Gene expression studies suggest a central role for both ethylene and JA pathways in the regulation of defense gene expression triggered by the pathogen or by plant cell wall-degrading enzymes (CF) secreted by the pathogen. Our results suggest that ethylene and JA act in concert in this regulation. In addition, CF triggers another, strictly JA-mediated response inhibited by ethylene and SA. SA does not appear to have a major role in activating defense gene expression in response to CF. However, SA may have a dual role in controlling CF-induced gene expression, by enhancing the expression of genes synergistically induced by ethylene and JA and repressing genes induced by JA alone.

  8. Yeast cell wall extract induces disease resistance against bacterial and fungal pathogens in Arabidopsis thaliana and Brassica crop.

    Directory of Open Access Journals (Sweden)

    Mari Narusaka

    Full Text Available Housaku Monogatari (HM is a plant activator prepared from a yeast cell wall extract. We examined the efficacy of HM application and observed that HM treatment increased the resistance of Arabidopsis thaliana and Brassica rapa leaves to bacterial and fungal infections. HM reduced the severity of bacterial leaf spot and anthracnose on A. thaliana and Brassica crop leaves with protective effects. In addition, gene expression analysis of A. thaliana plants after treatment with HM indicated increased expression of several plant defense-related genes. HM treatment appears to induce early activation of jasmonate/ethylene and late activation of salicylic acid (SA pathways. Analysis using signaling mutants revealed that HM required SA accumulation and SA signaling to facilitate resistance to the bacterial pathogen Pseudomonas syringae pv. maculicola and the fungal pathogen Colletotrichum higginsianum. In addition, HM-induced resistance conferred chitin-independent disease resistance to bacterial pathogens in A. thaliana. These results suggest that HM contains multiple microbe-associated molecular patterns that activate defense responses in plants. These findings suggest that the application of HM is a useful tool that may facilitate new disease control methods.

  9. The Fanconi anemia ortholog FANCM ensures ordered homologous recombination in both somatic and meiotic cells in Arabidopsis.

    Science.gov (United States)

    Knoll, Alexander; Higgins, James D; Seeliger, Katharina; Reha, Sarah J; Dangel, Natalie J; Bauknecht, Markus; Schröpfer, Susan; Franklin, F Christopher H; Puchta, Holger

    2012-04-01

    The human hereditary disease Fanconi anemia leads to severe symptoms, including developmental defects and breakdown of the hematopoietic system. It is caused by single mutations in the FANC genes, one of which encodes the DNA translocase FANCM (for Fanconi anemia complementation group M), which is required for the repair of DNA interstrand cross-links to ensure replication progression. We identified a homolog of FANCM in Arabidopsis thaliana that is not directly involved in the repair of DNA lesions but suppresses spontaneous somatic homologous recombination via a RecQ helicase (At-RECQ4A)-independent pathway. In addition, it is required for double-strand break-induced homologous recombination. The fertility of At-fancm mutant plants is compromised. Evidence suggests that during meiosis At-FANCM acts as antirecombinase to suppress ectopic recombination-dependent chromosome interactions, but this activity is antagonized by the ZMM pathway to enable the formation of interference-sensitive crossovers and chromosome synapsis. Surprisingly, mutation of At-FANCM overcomes the sterility phenotype of an At-MutS homolog4 mutant by apparently rescuing a proportion of crossover-designated recombination intermediates via a route that is likely At-MMS and UV sensitive81 dependent. However, this is insufficient to ensure the formation of an obligate crossover. Thus, At-FANCM is not only a safeguard for genome stability in somatic cells but is an important factor in the control of meiotic crossover formation.

  10. An improved method for preparing Agrobacterium cells that simplifies the Arabidopsis transformation protocol

    Directory of Open Access Journals (Sweden)

    Ülker Bekir

    2006-10-01

    Full Text Available Abstract Background The Agrobacterium vacuum (Bechtold et al 1993 and floral-dip (Clough and Bent 1998 are very efficient methods for generating transgenic Arabidopsis plants. These methods allow plant transformation without the need for tissue culture. Large volumes of bacterial cultures grown in liquid media are necessary for both of these transformation methods. This limits the number of transformations that can be done at a given time due to the need for expensive large shakers and limited space on them. Additionally, the bacterial colonies derived from solid media necessary for starting these liquid cultures often fail to grow in such large volumes. Therefore the optimum stage of plant material for transformation is often missed and new plant material needs to be grown. Results To avoid problems associated with large bacterial liquid cultures, we investigated whether bacteria grown on plates are also suitable for plant transformation. We demonstrate here that bacteria grown on plates can be used with similar efficiency for transforming plants even after one week of storage at 4°C. This makes it much easier to synchronize Agrobacterium and plants for transformation. DNA gel blot analysis was carried out on the T1 plants surviving the herbicide selection and demonstrated that the surviving plants are indeed transgenic. Conclusion The simplified method works as efficiently as the previously reported protocols and significantly reduces the workload, cost and time. Additionally, the protocol reduces the risk of large scale contaminations involving GMOs. Most importantly, many more independent transformations per day can be performed using this modified protocol.

  11. Acyl chains of phospholipase D transphosphatidylation products in Arabidopsis cells: a study using multiple reaction monitoring mass spectrometry.

    Directory of Open Access Journals (Sweden)

    Dominique Rainteau

    Full Text Available BACKGROUND: Phospholipases D (PLD are major components of signalling pathways in plant responses to some stresses and hormones. The product of PLD activity is phosphatidic acid (PA. PAs with different acyl chains do not have the same protein targets, so to understand the signalling role of PLD it is essential to analyze the composition of its PA products in the presence and absence of an elicitor. METHODOLOGY/PRINCIPAL FINDINGS: Potential PLD substrates and products were studied in Arabidopsis thaliana suspension cells treated with or without the hormone salicylic acid (SA. As PA can be produced by enzymes other than PLD, we analyzed phosphatidylbutanol (PBut, which is specifically produced by PLD in the presence of n-butanol. The acyl chain compositions of PBut and the major glycerophospholipids were determined by multiple reaction monitoring (MRM mass spectrometry. PBut profiles of untreated cells or cells treated with SA show an over-representation of 160/18:2- and 16:0/18:3-species compared to those of phosphatidylcholine and phosphatidylethanolamine either from bulk lipid extracts or from purified membrane fractions. When microsomal PLDs were used in in vitro assays, the resulting PBut profile matched exactly that of the substrate provided. Therefore there is a mismatch between the acyl chain compositions of putative substrates and the in vivo products of PLDs that is unlikely to reflect any selectivity of PLDs for the acyl chains of substrates. CONCLUSIONS: MRM mass spectrometry is a reliable technique to analyze PLD products. Our results suggest that PLD action in response to SA is not due to the production of a stress-specific molecular species, but that the level of PLD products per se is important. The over-representation of 160/18:2- and 16:0/18:3-species in PLD products when compared to putative substrates might be related to a regulatory role of the heterogeneous distribution of glycerophospholipids in membrane sub-domains.

  12. The development and geometry of shape change in Arabidopsis thaliana cotyledon pavement cells.

    Science.gov (United States)

    Zhang, Chunhua; Halsey, Leah E; Szymanski, Daniel B

    2011-02-01

    The leaf epidermis is an important architectural control element that influences the growth properties of underlying tissues and the overall form of the organ. In dicots, interdigitated pavement cells are the building blocks of the tissue, and their morphogenesis includes the assembly of specialized cell walls that surround the apical, basal, and lateral (anticlinal) cell surfaces. The microtubule and actin cytoskeletons are highly polarized along the cortex of the anticlinal wall; however, the relationships between these arrays and cell morphogenesis are unclear. We developed new quantitative tools to compare population-level growth statistics with time-lapse imaging of cotyledon pavement cells in an intact tissue. The analysis revealed alternating waves of lobe initiation and a phase of lateral isotropic expansion that persisted for days. During lateral isotropic diffuse growth, microtubule organization varied greatly between cell surfaces. Parallel microtubule bundles were distributed unevenly along the anticlinal surface, with subsets marking stable cortical domains at cell indentations and others clearly populating the cortex within convex cell protrusions. Pavement cell morphogenesis is discontinuous, and includes punctuated phases of lobe initiation and lateral isotropic expansion. In the epidermis, lateral isotropic growth is independent of pavement cell size and shape. Cortical microtubules along the upper cell surface and stable cortical patches of anticlinal microtubules may coordinate the growth behaviors of orthogonal cell walls. This work illustrates the importance of directly linking protein localization data to the growth behavior of leaf epidermal cells.

  13. Arabidopsis VARIEGATED 3 encodes a chloroplast-targeted, zinc-finger protein required for chloroplast and palisade cell development

    DEFF Research Database (Denmark)

    Næsted, Henrik; Holm, Agnethe; Jenkins, Tom

    2004-01-01

    The stable, recessive Arabidopsis variegated 3 (var3) mutant exhibits a variegated phenotype due to somatic areas lacking or containing developmentally retarded chloroplasts and greatly reduced numbers of palisade cells. The VAR3 gene, isolated by transposon tagging, encodes the 85.9 kDa VAR3...... that pigment profiles are qualitatively similar in wild type and var3, although var3 accumulates lower levels of chlorophylls and carotenoids. These results indicate that VAR3 is a part of a protein complex required for normal chloroplast and palisade cell development....

  14. Recruitment of glutathione into the nucleus during cell proliferation adjusts whole-cell redox homeostasis in Arabidopsis thaliana and lowers the oxidative defence shield.

    Science.gov (United States)

    Vivancos, Pedro Diaz; Dong, Yingping; Ziegler, Kerstin; Markovic, Jelena; Pallardó, Federico V; Pellny, Till K; Verrier, Paul J; Foyer, Christine H

    2010-12-01

    Cellular redox homeostasis and signalling are important in progression of the eukaryotic cell cycle. In animals, the low-molecular-weight thiol tripeptide glutathione (GSH) is recruited into the nucleus early in the cell proliferation cycle. To determine whether a similar process occurs in plants, we studied cell proliferation in Arabidopsis thaliana. We show that GSH co-localizes with nuclear DNA during the proliferation of A. thaliana cells in culture. Moreover, GSH localization in the nucleus was observed in dividing pericycle cells of the lateral root meristem. There was pronounced accumulation of GSH in the nucleus at points in the growth cycle at which a high percentage of the cells were in G(1) phase, as identified by flow cytometry and marker transcripts. Recruitment of GSH into the nucleus led to a high abundance of GSH in the nucleus (GSHn) and severe depletion of the cytoplasmic GSH pool (GSHc). Sequestration of GSH in the nucleus was accompanied by significant decreases in transcripts associated with oxidative signalling and stress tolerance, and an increase in the abundance of hydrogen peroxide, an effect that was enhanced when the dividing cells were treated with salicylic acid. Total cellular GSH and the abundance of GSH1 and GSH2 transcripts increased after the initial recruitment of GSH into the nucleus. We conclude that GSH recruitment into the nucleus during cell proliferation has a profound effect on the whole-cell redox state. High GSHn levels trigger redox adjustments in the cytoplasm, favouring decreased oxidative signalling and enhanced GSH synthesis. © 2010 The Authors. The Plant Journal © 2010 Blackwell Publishing Ltd.

  15. Chloroplasts activity and PAP-signaling regulate programmed cell death in Arabidopsis

    KAUST Repository

    Bruggeman, Quentin; Mazubert, Christelle; Prunier, Florence; Lugan, Raphael; Chan, Kai Xun; Phua, Su Yin; Pogson, Barry J.; Krieger-Liszkay, Anja; Delarue, Marianne; Benhamed, Moussa; Bergounioux, Catherine; Raynaud, Cé cile

    2016-01-01

    Programmed cell death (PCD) is a crucial process both for plant development and responses to biotic and abiotic stress. There is accumulating evidence that chloroplasts may play a central role during plant PCD as for mitochondria in animal cells

  16. COBRA-LIKE2, a member of the glycosylphosphatidylinositol-anchored COBRA-LIKE family, plays a role in cellulose deposition in arabidopsis seed coat mucilage secretory cells.

    Science.gov (United States)

    Ben-Tov, Daniela; Abraham, Yael; Stav, Shira; Thompson, Kevin; Loraine, Ann; Elbaum, Rivka; de Souza, Amancio; Pauly, Markus; Kieber, Joseph J; Harpaz-Saad, Smadar

    2015-03-01

    Differentiation of the maternally derived seed coat epidermal cells into mucilage secretory cells is a common adaptation in angiosperms. Recent studies identified cellulose as an important component of seed mucilage in various species. Cellulose is deposited as a set of rays that radiate from the seed upon mucilage extrusion, serving to anchor the pectic component of seed mucilage to the seed surface. Using transcriptome data encompassing the course of seed development, we identified COBRA-LIKE2 (COBL2), a member of the glycosylphosphatidylinositol-anchored COBRA-LIKE gene family in Arabidopsis (Arabidopsis thaliana), as coexpressed with other genes involved in cellulose deposition in mucilage secretory cells. Disruption of the COBL2 gene results in substantial reduction in the rays of cellulose present in seed mucilage, along with an increased solubility of the pectic component of the mucilage. Light birefringence demonstrates a substantial decrease in crystalline cellulose deposition into the cellulosic rays of the cobl2 mutants. Moreover, crystalline cellulose deposition into the radial cell walls and the columella appears substantially compromised, as demonstrated by scanning electron microscopy and in situ quantification of light birefringence. Overall, the cobl2 mutants display about 40% reduction in whole-seed crystalline cellulose content compared with the wild type. These data establish that COBL2 plays a role in the deposition of crystalline cellulose into various secondary cell wall structures during seed coat epidermal cell differentiation. © 2015 American Society of Plant Biologists. All Rights Reserved.

  17. Simultaneous cell tracking and image alignment in 3D CLSM imagery of growing arabidopsis thaliana sepals

    NARCIS (Netherlands)

    Fick, R.H.J.; Fedorov, D.; Roeder, A.H.K.; Manjunath, B.S.

    2013-01-01

    In this research we propose a combined cell matching and image alignment method for tracking cells based on their nuclear locations in 3D fluorescent Confocal Laser Scanning Microscopy (CLSM) image sequences. We then apply it to study the cell division pattern in the developing sepal of the small

  18. Arabidopsis annexin1 mediates the radical-activated plasma membrane Ca²+- and K+-permeable conductance in root cells.

    Science.gov (United States)

    Laohavisit, Anuphon; Shang, Zhonglin; Rubio, Lourdes; Cuin, Tracey A; Véry, Anne-Aliénor; Wang, Aihua; Mortimer, Jennifer C; Macpherson, Neil; Coxon, Katy M; Battey, Nicholas H; Brownlee, Colin; Park, Ohkmae K; Sentenac, Hervé; Shabala, Sergey; Webb, Alex A R; Davies, Julia M

    2012-04-01

    Plant cell growth and stress signaling require Ca²⁺ influx through plasma membrane transport proteins that are regulated by reactive oxygen species. In root cell growth, adaptation to salinity stress, and stomatal closure, such proteins operate downstream of the plasma membrane NADPH oxidases that produce extracellular superoxide anion, a reactive oxygen species that is readily converted to extracellular hydrogen peroxide and hydroxyl radicals, OH•. In root cells, extracellular OH• activates a plasma membrane Ca²⁺-permeable conductance that permits Ca²⁺ influx. In Arabidopsis thaliana, distribution of this conductance resembles that of annexin1 (ANN1). Annexins are membrane binding proteins that can form Ca²⁺-permeable conductances in vitro. Here, the Arabidopsis loss-of-function mutant for annexin1 (Atann1) was found to lack the root hair and epidermal OH•-activated Ca²⁺- and K⁺-permeable conductance. This manifests in both impaired root cell growth and ability to elevate root cell cytosolic free Ca²⁺ in response to OH•. An OH•-activated Ca²⁺ conductance is reconstituted by recombinant ANN1 in planar lipid bilayers. ANN1 therefore presents as a novel Ca²⁺-permeable transporter providing a molecular link between reactive oxygen species and cytosolic Ca²⁺ in plants.

  19. Identification of transcription factors linked to cell cycle regulation in Arabidopsis

    OpenAIRE

    Dehghan Nayeri, Fatemeh

    2014-01-01

    Cell cycle is an essential process in growth and development of living organisms consists of the replication and mitotic phases separated by 2 gap phases; G1 and G2. It is tightly controlled at the molecular level and especially at the level of transcription. Precise regulation of the cell cycle is of central significance for plant growth and development and transcription factors are global regulators of gene expression playing essential roles in cell cycle regulation. This study has uncovere...

  20. The founder-cell transcriptome in the Arabidopsis apetala1 cauliflower inflorescence meristem.

    Science.gov (United States)

    Frerichs, Anneke; Thoma, Rahere; Abdallah, Ali Taleb; Frommolt, Peter; Werr, Wolfgang; Chandler, John William

    2016-11-03

    Although the pattern of lateral organ formation from apical meristems establishes species-specific plant architecture, the positional information that confers cell fate to cells as they transit to the meristem flanks where they differentiate, remains largely unknown. We have combined fluorescence-activated cell sorting and RNA-seq to characterise the cell-type-specific transcriptome at the earliest developmental time-point of lateral organ formation using DORNRÖSCHEN-LIKE::GFP to mark founder-cell populations at the periphery of the inflorescence meristem (IM) in apetala1 cauliflower double mutants, which overproliferate IMs. Within the lateral organ founder-cell population at the inflorescence meristem, floral primordium identity genes are upregulated and stem-cell identity markers are downregulated. Additional differentially expressed transcripts are involved in polarity generation and boundary formation, and in epigenetic and post-translational changes. However, only subtle transcriptional reprogramming within the global auxin network was observed. The transcriptional network of differentially expressed genes supports the hypothesis that lateral organ founder-cell specification involves the creation of polarity from the centre to the periphery of the IM and the establishment of a boundary from surrounding cells, consistent with bract initiation. However, contrary to the established paradigm that sites of auxin response maxima pre-pattern lateral organ initiation in the IM, auxin response might play a minor role in the earliest stages of lateral floral initiation.

  1. Arabidopsis Lectin Receptor Kinases LecRK-IX.1 and LecRK-IX.2 Are Functional Analogs in Regulating Phytophthora Resistance and Plant Cell Death.

    Science.gov (United States)

    Wang, Yan; Cordewener, Jan H G; America, Antoine H P; Shan, Weixing; Bouwmeester, Klaas; Govers, Francine

    2015-09-01

    L-type lectin receptor kinases (LecRK) are potential immune receptors. Here, we characterized two closely-related Arabidopsis LecRK, LecRK-IX.1 and LecRK-IX.2, of which T-DNA insertion mutants showed compromised resistance to Phytophthora brassicae and Phytophthora capsici, with double mutants showing additive susceptibility. Overexpression of LecRK-IX.1 or LecRK-IX.2 in Arabidopsis and transient expression in Nicotiana benthamiana increased Phytophthora resistance but also induced cell death. Phytophthora resistance required both the lectin domain and kinase activity, but for cell death, the lectin domain was not needed. Silencing of the two closely related mitogen-activated protein kinase genes NbSIPK and NbNTF4 in N. benthamiana completely abolished LecRK-IX.1-induced cell death but not Phytophthora resistance. Liquid chromatography-mass spectrometry analysis of protein complexes coimmunoprecipitated in planta with LecRK-IX.1 or LecRK-IX.2 as bait, resulted in the identification of the N. benthamiana ABC transporter NbPDR1 as a potential interactor of both LecRK. The closest homolog of NbPDR1 in Arabidopsis is ABCG40, and coimmunoprecipitation experiments showed that ABCG40 associates with LecRK-IX.1 and LecRK-IX.2 in planta. Similar to the LecRK mutants, ABCG40 mutants showed compromised Phytophthora resistance. This study shows that LecRK-IX.1 and LecRK-IX.2 are Phytophthora resistance components that function independent of each other and independent of the cell-death phenotype. They both interact with the same ABC transporter, suggesting that they exploit similar signal transduction pathways.

  2. Transcript Profiling Identifies NAC-Domain Genes Involved in Regulating Wall Ingrowth Deposition in Phloem Parenchyma Transfer Cells of Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Yuzhou Wu

    2018-03-01

    Full Text Available Transfer cells (TCs play important roles in facilitating enhanced rates of nutrient transport at key apoplasmic/symplasmic junctions along the nutrient acquisition and transport pathways in plants. TCs achieve this capacity by developing elaborate wall ingrowth networks which serve to increase plasma membrane surface area thus increasing the cell's surface area-to-volume ratio to achieve increased flux of nutrients across the plasma membrane. Phloem parenchyma (PP cells of Arabidopsis leaf veins trans-differentiate to become PP TCs which likely function in a two-step phloem loading mechanism by facilitating unloading of photoassimilates into the apoplasm for subsequent energy-dependent uptake into the sieve element/companion cell (SE/CC complex. We are using PP TCs in Arabidopsis as a genetic model to identify transcription factors involved in coordinating deposition of the wall ingrowth network. Confocal imaging of pseudo-Schiff propidium iodide-stained tissue revealed different profiles of temporal development of wall ingrowth deposition across maturing cotyledons and juvenile leaves, and a basipetal gradient of deposition across mature adult leaves. RNA-Seq analysis was undertaken to identify differentially expressed genes common to these three different profiles of wall ingrowth deposition. This analysis identified 68 transcription factors up-regulated two-fold or more in at least two of the three experimental comparisons, with six of these transcription factors belonging to Clade III of the NAC-domain family. Phenotypic analysis of these NAC genes using insertional mutants revealed significant reductions in levels of wall ingrowth deposition, particularly in a double mutant of NAC056 and NAC018, as well as compromised sucrose-dependent root growth, indicating impaired capacity for phloem loading. Collectively, these results support the proposition that Clade III members of the NAC-domain family in Arabidopsis play important roles in

  3. 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.

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

    International Nuclear Information System (INIS)

    Zhu, Xiao Fang; Wang, Zhi Wei; Dong, Fang; Lei, Gui Jie; Shi, Yuan Zhi; Li, Gui Xin; Zheng, Shao Jian

    2013-01-01

    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 2+ ) stress decreased the endogenous auxin level, whereas exogenous auxin (α-naphthaleneacetic acid, NAA, a permeable auxin analog) reduced shoot Cd 2+ concentration and rescued Cd 2+ -induced chlorosis in Arabidopsis thaliana. Under Cd 2+ stress conditions, NAA increased Cd 2+ retention in the roots and most Cd 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 2+ , whereas it significantly increased the content of hemicellulose 1 and the amount of Cd 2+ retained in it. There were highly significant correlations between Cd 2+ concentrations in the root, cell wall and hemicellulose 1 when the plants were subjected to Cd 2+ or NAA + Cd 2+ treatment for 1 to 7 d, suggesting that the increase in hemicellulose 1 contributes greatly to the fixation of Cd 2+ in the cell wall. Taken together, these results demonstrate that auxin-induced alleviation of Cd 2+ toxicity in Arabidopsis is mediated through increasing hemicellulose 1 content and Cd 2+ fixation in the root, thus reducing the translocation of Cd 2+ from roots to shoots

  5. Cellulose-Pectin Spatial Contacts Are Inherent to Never-Dried Arabidopsis Primary Cell Walls: Evidence from Solid-State Nuclear Magnetic Resonance1[OPEN

    Science.gov (United States)

    Wang, Tuo; Park, Yong Bum; Hong, Mei

    2015-01-01

    The structural role of pectins in plant primary cell walls is not yet well understood because of the complex and disordered nature of the cell wall polymers. We recently introduced multidimensional solid-state nuclear magnetic resonance spectroscopy to characterize the spatial proximities of wall polysaccharides. The data showed extensive cross peaks between pectins and cellulose in the primary wall of Arabidopsis (Arabidopsis thaliana), indicating subnanometer contacts between the two polysaccharides. This result was unexpected because stable pectin-cellulose interactions are not predicted by in vitro binding assays and prevailing cell wall models. To investigate whether the spatial contacts that give rise to the cross peaks are artifacts of sample preparation, we now compare never-dried Arabidopsis primary walls with dehydrated and rehydrated samples. One-dimensional 13C spectra, two-dimensional 13C-13C correlation spectra, water-polysaccharide correlation spectra, and dynamics data all indicate that the structure, mobility, and intermolecular contacts of the polysaccharides are indistinguishable between never-dried and rehydrated walls. Moreover, a partially depectinated cell wall in which 40% of homogalacturonan is extracted retains cellulose-pectin cross peaks, indicating that the cellulose-pectin contacts are not due to molecular crowding. The cross peaks are observed both at −20°C and at ambient temperature, thus ruling out freezing as a cause of spatial contacts. These results indicate that rhamnogalacturonan I and a portion of homogalacturonan have significant interactions with cellulose microfibrils in the native primary wall. This pectin-cellulose association may be formed during wall biosynthesis and may involve pectin entrapment in or between cellulose microfibrils, which cannot be mimicked by in vitro binding assays. PMID:26036615

  6. AGL61 interacts with AGL80 and is required for central cell development in Arabidopsis.

    Science.gov (United States)

    Steffen, Joshua G; Kang, Il-Ho; Portereiko, Michael F; Lloyd, Alan; Drews, Gary N

    2008-09-01

    The central cell of the female gametophyte plays a role in pollen tube guidance and in regulating the initiation of endosperm development. Following fertilization, the central cell gives rise to the seed's endosperm, which nourishes the developing embryo within the seed. The molecular mechanisms controlling specification and differentiation of the central cell are poorly understood. We identified AGL61 in a screen for transcription factor genes expressed in the female gametophyte. AGL61 encodes a Type I MADS domain protein, which likely functions as a transcription factor. Consistent with this, an AGL61-green fluorescent protein fusion protein is localized to the nucleus. In the context of the ovule and seed, AGL61 is expressed exclusively in the central cell and early endosperm. agl61 female gametophytes are affected in the central cell specifically. The morphological defects include an overall reduction in size of the central cell and a reduced or absent central cell vacuole. When fertilized with wild-type pollen, agl61 central cells fail to give rise to endosperm. In addition, synergid- and antipodal-expressed genes are ectopically expressed in agl61 central cells. The expression pattern and mutant phenotype of AGL61 are similar to those of AGL80, suggesting that AGL61 may function as a heterodimer with AGL80 within the central cell; consistent with this, AGL61 and AGL80 interact in yeast two-hybrid assays. Together, these data suggest that AGL61 functions as a transcription factor and controls the expression of downstream genes during central cell development.

  7. Cell fate in the Arabidopsis root meristem determined by directional signalling

    NARCIS (Netherlands)

    Berg, C. van den; Willemsen, V.; Hage, W.; Weisbeek, P.; Scheres, B.J.G.

    1995-01-01

    Postembryonic development in plants is achieved by apical meristems. Surgical studies and clonal analysis have revealed indirectly that cells in shoot meristems have no predictable destiny and that position is likely to play a role in the acquisition of cell identity . In contrast to animal

  8. Common and unique elements of the ABA-regulated transcriptome of Arabidopsis guard cells

    Directory of Open Access Journals (Sweden)

    Zhao Zhixin

    2011-05-01

    Full Text Available Abstract Background In the presence of drought and other desiccating stresses, plants synthesize and redistribute the phytohormone abscisic acid (ABA. ABA promotes plant water conservation by acting on specialized cells in the leaf epidermis, guard cells, which border and regulate the apertures of stomatal pores through which transpirational water loss occurs. Following ABA exposure, solute uptake into guard cells is rapidly inhibited and solute loss is promoted, resulting in inhibition of stomatal opening and promotion of stomatal closure, with consequent plant water conservation. There is a wealth of information on the guard cell signaling mechanisms underlying these rapid ABA responses. To investigate ABA regulation of gene expression in guard cells in a systematic genome-wide manner, we analyzed data from global transcriptomes of guard cells generated with Affymetrix ATH1 microarrays, and compared these results to ABA regulation of gene expression in leaves and other tissues. Results The 1173 ABA-regulated genes of guard cells identified by our study share significant overlap with ABA-regulated genes of other tissues, and are associated with well-defined ABA-related promoter motifs such as ABREs and DREs. However, we also computationally identified a unique cis-acting motif, GTCGG, associated with ABA-induction of gene expression specifically in guard cells. In addition, approximately 300 genes showing ABA-regulation unique to this cell type were newly uncovered by our study. Within the ABA-regulated gene set of guard cells, we found that many of the genes known to encode ion transporters associated with stomatal opening are down-regulated by ABA, providing one mechanism for long-term maintenance of stomatal closure during drought. We also found examples of both negative and positive feedback in the transcriptional regulation by ABA of known ABA-signaling genes, particularly with regard to the PYR/PYL/RCAR class of soluble ABA receptors and

  9. Common and unique elements of the ABA-regulated transcriptome of Arabidopsis guard cells

    Science.gov (United States)

    2011-01-01

    Background In the presence of drought and other desiccating stresses, plants synthesize and redistribute the phytohormone abscisic acid (ABA). ABA promotes plant water conservation by acting on specialized cells in the leaf epidermis, guard cells, which border and regulate the apertures of stomatal pores through which transpirational water loss occurs. Following ABA exposure, solute uptake into guard cells is rapidly inhibited and solute loss is promoted, resulting in inhibition of stomatal opening and promotion of stomatal closure, with consequent plant water conservation. There is a wealth of information on the guard cell signaling mechanisms underlying these rapid ABA responses. To investigate ABA regulation of gene expression in guard cells in a systematic genome-wide manner, we analyzed data from global transcriptomes of guard cells generated with Affymetrix ATH1 microarrays, and compared these results to ABA regulation of gene expression in leaves and other tissues. Results The 1173 ABA-regulated genes of guard cells identified by our study share significant overlap with ABA-regulated genes of other tissues, and are associated with well-defined ABA-related promoter motifs such as ABREs and DREs. However, we also computationally identified a unique cis-acting motif, GTCGG, associated with ABA-induction of gene expression specifically in guard cells. In addition, approximately 300 genes showing ABA-regulation unique to this cell type were newly uncovered by our study. Within the ABA-regulated gene set of guard cells, we found that many of the genes known to encode ion transporters associated with stomatal opening are down-regulated by ABA, providing one mechanism for long-term maintenance of stomatal closure during drought. We also found examples of both negative and positive feedback in the transcriptional regulation by ABA of known ABA-signaling genes, particularly with regard to the PYR/PYL/RCAR class of soluble ABA receptors and their downstream targets

  10. AtLa1 protein initiates IRES-dependent translation of WUSCHEL mRNA and regulates the stem cell homeostasis of Arabidopsis in response to environmental hazards.

    Science.gov (United States)

    Cui, Yuchao; Rao, Shaofei; Chang, Beibei; Wang, Xiaoshuang; Zhang, Kaidian; Hou, Xueliang; Zhu, Xueyi; Wu, Haijun; Tian, Zhaoxia; Zhao, Zhong; Yang, Chengwei; Huang, Tao

    2015-10-01

    Plant stem cells are hypersensitive to environmental hazards throughout their life cycle, but the mechanism by which plants safeguard stem cell homeostasis in response to environmental hazards is largely unknown. The homeodomain transcription factor WUSCHEL (WUS) protein maintains the stem cell pool in the shoot apical meristem of Arabidopsis. Here, we demonstrate that the translation of WUS mRNA is directed by an internal ribosomal entry site (IRES) located in the 5'-untranslated region. The AtLa1 protein, an RNA-binding factor, binds to the 5'-untranslated region and initiates the IRES-dependent translation of WUS mRNA. Knockdown of AtLa1 expression represses the WUS IRES-dependent translation and leads to the arrest of growth and development. The AtLa1 protein is mainly located in the nucleoplasm. However, environmental hazards promote the nuclear-to-cytoplasmic translocation of the AtLa1 protein, which further enhances the IRES-dependent translation of WUS mRNA. Genetic evidence indicates that the WUS protein increases the tolerance of the shoot apical meristem to environmental hazards. Based on these results, we conclude that the stem cell niche in Arabidopsis copes with environmental hazards by enhancing the IRES-dependent translation of WUS mRNA under the control of the AtLa1 protein. © 2015 John Wiley & Sons Ltd.

  11. Combining laser-assisted microdissection (LAM) and RNA-seq allows to perform a comprehensive transcriptomic analysis of epidermal cells of Arabidopsis embryo.

    Science.gov (United States)

    Sakai, Kaori; Taconnat, Ludivine; Borrega, Nero; Yansouni, Jennifer; Brunaud, Véronique; Paysant-Le Roux, Christine; Delannoy, Etienne; Martin Magniette, Marie-Laure; Lepiniec, Loïc; Faure, Jean Denis; Balzergue, Sandrine; Dubreucq, Bertrand

    2018-01-01

    Genome-wide characterization of tissue- or cell-specific gene expression is a recurrent bottleneck in biology. We have developed a sensitive approach based on ultra-low RNA sequencing coupled to laser assisted microdissection for analyzing different tissues of the small Arabidopsis embryo. We first characterized the number of genes detected according to the quantity of tissue yield and total RNA extracted. Our results revealed that as low as 0.02 mm 2 of tissue and 50 pg of total RNA can be used without compromising the number of genes detected. The optimised protocol was used to compare the epidermal versus mesophyll cell transcriptomes of cotyledons at the torpedo-shaped stage of embryo development. The approach was validated by the recovery of well-known epidermal genes such AtML1 or AtPDF2 and genes involved in flavonoid and cuticular waxes pathways. Moreover, the interest and sensitivity of this approach were highlighted by the characterization of several transcription factors preferentially expressed in epidermal cells. This technical advance unlocks some current limitations of transcriptomic analyses and allows to investigate further and efficiently new biological questions for which only a very small amounts of cells need to be isolated. For instance, it paves the way to increasing the spatial accuracy of regulatory networks in developing small embryo of Arabidopsis or other plant tissues.

  12. Enhancement of cell wall protein SRPP expression during emergent root hair development in Arabidopsis.

    Science.gov (United States)

    Uno, Hiroshi; Tanaka-Takada, Natsuki; Sato, Ryosuke; Maeshima, Masayoshi

    2017-10-03

    SRPP is a protein expressed in seeds and root hairs and is significantly induced in root hairs under phosphate (Pi)-deficient conditions. Root hairs in the knockout mutant srpp-1 display defects, i.e., suppression of cell growth and cell death. Here, we analyzed the expression profile of SRPP during cell elongation of root hairs and compared the transcript levels in several mutants with short root hairs. The mRNA level was increased in wild-type plants and decreased in mutants with short root hairs. Induction of SRPP expression by Pi starvation occurred one or two days later than induction of Pi-deficient sensitive genes, such as PHT1 and PHF1. These results indicate that the expression of SRPP is coordinated with root hair elongation. We hypothesize that SRPP is essential for structural robustness of the cell walls of root hairs.

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

    Science.gov (United States)

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

    2015-12-01

    Catalases are reactive oxygen species scavenging enzymes involved in response to abiotic and biotic stresses. In this study, we described the isolation and functional characterization of a novel catalase from durum wheat, designed TdCAT1. Molecular Phylogeny analyses showed that wheat TdCAT1 exhibited high amino acids sequence identity to other plant catalases. Sequence homology analysis showed that TdCAT1 protein contained the putative calmodulin binding domain and a putative conserved internal peroxisomal targeting signal PTS1 motif around its C-terminus. Predicted three-dimensional structural model revealed the presence of four putative distinct structural regions which are the N-terminal arm, the β-barrel, the wrapping and the α-helical domains. TdCAT1 protein had the heme pocket that was composed by five essential residues. TdCAT1 gene expression analysis showed that this gene was induced by various abiotic stresses in durum wheat. The expression of TdCAT1 in yeast cells and Arabidopsis plants conferred tolerance to several abiotic stresses. Compared with the non-transformed plants, the transgenic lines maintained their growth and accumulated more proline under stress treatments. Furthermore, the amount of H2O2 was lower in transgenic lines, which was due to the high CAT and POD activities. Taken together, these data provide the evidence for the involvement of durum wheat catalase TdCAT1 in tolerance to multiple abiotic stresses in crop plants. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  14. Information flow during gene activation by signaling molecules: ethylene transduction in Arabidopsis cells as a study system

    Directory of Open Access Journals (Sweden)

    Díaz José

    2009-05-01

    Full Text Available Abstract Background We study root cells from the model plant Arabidopsis thaliana and the communication channel conformed by the ethylene signal transduction pathway. A basic equation taken from our previous work relates the probability of expression of the gene ERF1 to the concentration of ethylene. Results The above equation is used to compute the Shannon entropy (H or degree of uncertainty that the genetic machinery has during the decoding of the message encoded by the ethylene specific receptors embedded in the endoplasmic reticulum membrane and transmitted into the nucleus by the ethylene signaling pathway. We show that the amount of information associated with the expression of the master gene ERF1 (Ethylene Response Factor 1 can be computed. Then we examine the system response to sinusoidal input signals with varying frequencies to determine if the cell can distinguish between different regimes of information flow from the environment. Our results demonstrate that the amount of information managed by the root cell can be correlated with the frequency of the input signal. Conclusion The ethylene signaling pathway cuts off very low and very high frequencies, allowing a window of frequency response in which the nucleus reads the incoming message as a sinusoidal input. Out of this window the nucleus reads the input message as an approximately non-varying one. From this frequency response analysis we estimate: a the gain of the system during the synthesis of the protein ERF1 (~-5.6 dB; b the rate of information transfer (0.003 bits during the transport of each new ERF1 molecule into the nucleus and c the time of synthesis of each new ERF1 molecule (~21.3 s. Finally, we demonstrate that in the case of the system of a single master gene (ERF1 and a single slave gene (HLS1, the total Shannon entropy is completely determined by the uncertainty associated with the expression of the master gene. A second proposition shows that the Shannon entropy

  15. Chloroplasts activity and PAP-signaling regulate programmed cell death in Arabidopsis

    KAUST Repository

    Bruggeman, Quentin

    2016-01-09

    Programmed cell death (PCD) is a crucial process both for plant development and responses to biotic and abiotic stress. There is accumulating evidence that chloroplasts may play a central role during plant PCD as for mitochondria in animal cells, but it is still unclear whether they participate in PCD onset, execution, or both. To tackle this question, we have analyzed the contribution of chloroplast function to the cell death phenotype of the myoinositol phosphate synthase1 (mips1) mutant that forms spontaneous lesions in a light-dependent manner. We show that photosynthetically active chloroplasts are required for PCD to occur in mips1, but this process is independent of the redox state of the chloroplast. Systematic genetic analyses with retrograde signaling mutants reveal that 3’-phosphoadenosine 5’-phosphate, a chloroplast retrograde signal that modulates nuclear gene expression in response to stress, can inhibit cell death and compromises plant innate immunity via inhibition of the RNA-processing 5’-3’ exoribonucleases. Our results provide evidence for the role of chloroplast-derived signal and RNA metabolism in the control of cell death and biotic stress response. © 2016 American Society of Plant Biologists. All Rights Reserved.

  16. A temperature-sensitive allele of a putative mRNA splicing helicase down-regulates many cell wall genes and causes radial swelling in Arabidopsis thaliana.

    Science.gov (United States)

    Howles, Paul A; Gebbie, Leigh K; Collings, David A; Varsani, Arvind; Broad, Ronan C; Ohms, Stephen; Birch, Rosemary J; Cork, Ann H; Arioli, Tony; Williamson, Richard E

    2016-05-01

    The putative RNA helicase encoded by the Arabidopsis gene At1g32490 is a homolog of the yeast splicing RNA helicases Prp2 and Prp22. We isolated a temperature-sensitive allele (rsw12) of the gene in a screen for root radial swelling mutants. Plants containing this allele grown at the restrictive temperature showed weak radial swelling, were stunted with reduced root elongation, and contained reduced levels of cellulose. The role of the protein was further explored by microarray analysis. By using both fold change cutoffs and a weighted gene coexpression network analysis (WGCNA) to investigate coexpression of genes, we found that the radial swelling phenotype was not linked to genes usually associated with primary cell wall biosynthesis. Instead, the mutation has strong effects on expression of secondary cell wall related genes. Many genes potentially associated with secondary walls were present in the most significant WGCNA module, as were genes coding for arabinogalactans and proteins with GPI anchors. The proportion of up-regulated genes that possess introns in rsw12 was above that expected if splicing was unrelated to the activity of the RNA helicase, suggesting that the helicase does indeed play a role in splicing in Arabidopsis. The phenotype may be due to a change in the expression of one or more genes coding for cell wall proteins.

  17. A mutation in a coproporphyrinogen III oxidase gene confers growth inhibition, enhanced powdery mildew resistance and powdery mildew-induced cell death in Arabidopsis.

    Science.gov (United States)

    Guo, Chuan-yu; Wu, Guang-heng; Xing, Jin; Li, Wen-qi; Tang, Ding-zhong; Cui, Bai-ming

    2013-05-01

    A gene encoding a coproporphyrinogen III oxidase mediates disease resistance in plants by the salicylic acid pathway. A number of genes that regulate powdery mildew resistance have been identified in Arabidopsis, such as ENHANCED DISEASE RESISTANCE 1 to 3 (EDR1 to 3). To further study the molecular interactions between the powdery mildew pathogen and Arabidopsis, we isolated and characterized a mutant that exhibited enhanced resistance to powdery mildew. The mutant also showed dramatic powdery mildew-induced cell death as well as growth defects and early senescence in the absence of pathogens. We identified the affected gene by map-based cloning and found that the gene encodes a coproporphyrinogen III oxidase, a key enzyme in the tetrapyrrole biosynthesis pathway, previously known as LESION INITIATION 2 (LIN2). Therefore, we designated the mutant lin2-2. Further studies revealed that the lin2-2 mutant also displayed enhanced resistance to Hyaloperonospora arabidopsidis (H.a.) Noco2. Genetic analysis showed that the lin2-2-mediated disease resistance and spontaneous cell death were dependent on PHYTOALEXIN DEFICIENT 4 (PAD4), SALICYLIC ACID INDUCTION-DEFICIENT 2 (SID2), and NONEXPRESSOR OF PATHOGENESIS-RELATED GENES 1 (NPR1), which are all involved in salicylic acid signaling. Furthermore, the relative expression levels of defense-related genes were induced after powdery mildew infection in the lin2-2 mutant. These data indicated that LIN2 plays an important role in cell death control and defense responses in plants.

  18. Unidirectional Movement of Cellulose Synthase Complexes in Arabidopsis Seed Coat Epidermal Cells Deposit Cellulose Involved in Mucilage Extrusion, Adherence, and Ray Formation1[OPEN

    Science.gov (United States)

    Lam, Patricia; Young, Robin; DeBolt, Seth

    2015-01-01

    CELLULOSE SYNTHASE5 (CESA5) synthesizes cellulose necessary for seed mucilage adherence to seed coat epidermal cells of Arabidopsis (Arabidopsis thaliana). The involvement of additional CESA proteins in this process and details concerning the manner in which cellulose is deposited in the mucilage pocket are unknown. Here, we show that both CESA3 and CESA10 are highly expressed in this cell type at the time of mucilage synthesis and localize to the plasma membrane adjacent to the mucilage pocket. The isoxaben resistant1-1 and isoxaben resistant1-2 mutants affecting CESA3 show defects consistent with altered mucilage cellulose biosynthesis. CESA3 can interact with CESA5 in vitro, and green fluorescent protein-tagged CESA5, CESA3, and CESA10 proteins move in a linear, unidirectional fashion around the cytoplasmic column of the cell, parallel with the surface of the seed, in a pattern similar to that of cortical microtubules. Consistent with this movement, cytological evidence suggests that the mucilage is coiled around the columella and unwinds during mucilage extrusion to form a linear ray. Mutations in CESA5 and CESA3 affect the speed of mucilage extrusion and mucilage adherence. These findings imply that cellulose fibrils are synthesized in an ordered helical array around the columella, providing a distinct structure to the mucilage that is important for both mucilage extrusion and adherence. PMID:25926481

  19. Analysis of gene expression in the outer cell layers of Arabidopsis roots during lateral root development

    NARCIS (Netherlands)

    Veth-Tello, Luz Marina

    2005-01-01

    Lateral roots are an important means for the plant to increase its absorptive area and the volume of substrate exploited. Lateral roots originate in the pericycle, the outermost layer of the vascular cylinder, and by growing penetrate the overlaying cell layers before emergence. This process is

  20. The zinc finger protein ZAT11 modulates paraquat-induced programmed cell death in Arabidopsis thaliana

    NARCIS (Netherlands)

    Qureshi, Muhammad Kamran; Sujeeth, Neerakkal; Gechev, Tsanko S.; Hille, Jacques

    Plants use programmed cell death (PCD) as a tool in their growth and development. PCD is also involved in defense against different kinds of stresses including pathogen attack. In both types of PCD, reactive oxygen species (ROS) play an important role. ROS is not only a toxic by-product but also

  1. Expression of the Arabidopsis high-affinity hexose transporter STP13 correlates with programmed cell death

    DEFF Research Database (Denmark)

    Nørholm, Morten Helge Hauberg; Nour-Eldin, Hussam H; Brodersen, Peter

    2006-01-01

    GFP expression only in the vascular tissue in emerging petals under non-stressed conditions. Quantitative PCR and the pSTP13-GFP plants show induction of STP13 in programmed cell death (PCD) obtained by treatments with the fungal toxin fumonisin B1 and the pathogen Pseudomonas syringae. A role for STP...

  2. UV-B inhibition of hypocotyl growth in etiolated Arabidopsis thaliana seedlings is a consequence of cell cycle arrest initiated by photodimer accumulation

    Science.gov (United States)

    Biever, Jessica J.; Brinkman, Doug; Gardner, Gary

    2014-01-01

    Ultraviolet (UV) radiation is an important constituent of sunlight that determines plant morphology and growth. It induces photomorphogenic responses but also causes damage to DNA. Arabidopsis mutants of the endonucleases that function in nucleotide excision repair, xpf-3 and uvr1-1, showed hypersensitivity to UV-B (280–320nm) in terms of inhibition of hypocotyl growth. SOG1 is a transcription factor that functions in the DNA damage signalling response after γ-irradiation. xpf mutants that carry the sog1-1 mutation showed hypocotyl growth inhibition after UV-B irradiation similar to the wild type. A DNA replication inhibitor, hydroxyurea (HU), also inhibited hypocotyl growth in etiolated seedlings, but xpf-3 was not hypersensitive to HU. UV-B irradiation induced accumulation of the G2/M-specific cell cycle reporter construct CYCB1;1-GUS in wild-type Arabidopsis seedlings that was consistent with the expected accumulation of photodimers and coincided with the time course of hypocotyl growth inhibition after UV-B treatment. Etiolated mutants of UVR8, a recently described UV-B photoreceptor gene, irradiated with UV-B showed inhibition of hypocotyl growth that was not different from that of the wild type, but they lacked UV-B-specific expression of chalcone synthase (CHS), as expected from previous reports. CHS expression after UV-B irradiation was not different in xpf-3 compared with the wild type, nor was it altered after HU treatment. These results suggest that hypocotyl growth inhibition by UV-B light in etiolated Arabidopsis seedlings, a photomorphogenic response, is dictated by signals originating from UV-B absorption by DNA that lead to cell cycle arrest. This process occurs distinct from UVR8 and its signalling pathway responsible for CHS induction. PMID:24591052

  3. Signaling requirements for Erwinia amylovora-induced disease resistance, callose deposition, and cell growth in the nonhost Arabidopsis thaliana

    Science.gov (United States)

    Erwinia amylovora is the causal agent of the fire blight disease in some plants of the Rosaceae family. The nonhost plant Arabidopsis serves as a powerful system to dissect mechanisms of resistance to E. amylovora. Although not yet known to mount gene-for-gene resistance to E. amylovora, we found ...

  4. Function of type-2 Arabidopsis hemoglobin in the auxin-mediated formation of embryogenic cells during morphogenesis

    DEFF Research Database (Denmark)

    Elhiti, Mohamed; Hebelstrup, Kim; Wang, Aiming

    2013-01-01

    Suppression of the Arabidopsis GLB2, a type-2 nonsymbiotic hemoglobin, enhances somatic embryogenesis by increasing auxin production. In the glb2 knock-out line (GLB2 -/-) polarization of PIN1 proteins and auxin maxima occurred at the base of the cotyledons of the zygotic explants, which are the ...

  5. The Arabidopsis guard cell outward potassium channel GORK is regulated by CPK33.

    Science.gov (United States)

    Corratgé-Faillie, Claire; Ronzier, Elsa; Sanchez, Frédéric; Prado, Karine; Kim, Jeong-Hyeon; Lanciano, Sophie; Leonhardt, Nathalie; Lacombe, Benoît; Xiong, Tou Cheu

    2017-07-01

    A complex signaling network involving voltage-gated potassium channels from the Shaker family contributes to the regulation of stomatal aperture. Several kinases and phosphatases have been shown to be crucial for ABA-dependent regulation of the ion transporters. To date, the Ca 2+ -dependent regulation of Shaker channels by Ca 2+ -dependent protein kinases (CPKs) is still elusive. A functional screen in Xenopus oocytes was launched to identify such CPKs able to regulate the three main guard cell Shaker channels KAT1, KAT2, and GORK. Seven guard cell CPKs were tested and multiple CPK/Shaker couples were identified. Further work on CPK33 indicates that GORK activity is enhanced by CPK33 and unaffected by a nonfunctional CPK33 (CPK33-K102M). Furthermore, Ca 2+ -induced stomatal closure is impaired in two cpk33 mutant plants. © 2017 Federation of European Biochemical Societies.

  6. An Exocyst Complex Functions in Plant Cell Growth in Arabidopsis and Tobacco

    Czech Academy of Sciences Publication Activity Database

    Hála, Michal; Cole, R.A.; Synek, Lukáš; Drdová, Edita; Pečenková, Tamara; Nordheim, A.; Lamkemeyer, T.; Madlung, J.; Hochholdinger, F.; Fowler, J.E.; Žárský, Viktor

    2008-01-01

    Roč. 20, č. 5 (2008), s. 1330-1345 ISSN 1040-4651 R&D Projects: GA MŠk ME 841; GA MŠk(CZ) LC06034; GA AV ČR IAA6038410 Institutional research plan: CEZ:AV0Z50380511 Keywords : EXOCYST * PROTEIN COMPLEX * CELL POLARITY * MORPHOGENESIS * GTPASES Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 9.296, year: 2008

  7. Abscisic Acid–Responsive Guard Cell Metabolomes of Arabidopsis Wild-Type and gpa1 G-Protein Mutants[C][W

    Science.gov (United States)

    Jin, Xiaofen; Wang, Rui-Sheng; Zhu, Mengmeng; Jeon, Byeong Wook; Albert, Reka; Chen, Sixue; Assmann, Sarah M.

    2013-01-01

    Individual metabolites have been implicated in abscisic acid (ABA) signaling in guard cells, but a metabolite profile of this specialized cell type is lacking. We used liquid chromatography–multiple reaction monitoring mass spectrometry for targeted analysis of 85 signaling-related metabolites in Arabidopsis thaliana guard cell protoplasts over a time course of ABA treatment. The analysis utilized ∼350 million guard cell protoplasts from ∼30,000 plants of the Arabidopsis Columbia accession (Col) wild type and the heterotrimeric G-protein α subunit mutant, gpa1, which has ABA-hyposensitive stomata. These metabolomes revealed coordinated regulation of signaling metabolites in unrelated biochemical pathways. Metabolites clustered into different temporal modules in Col versus gpa1, with fewer metabolites showing ABA-altered profiles in gpa1. Ca2+-mobilizing agents sphingosine-1-phosphate and cyclic adenosine diphosphate ribose exhibited weaker ABA-stimulated increases in gpa1. Hormone metabolites were responsive to ABA, with generally greater responsiveness in Col than in gpa1. Most hormones also showed different ABA responses in guard cell versus mesophyll cell metabolomes. These findings suggest that ABA functions upstream to regulate other hormones, and are also consistent with G proteins modulating multiple hormonal signaling pathways. In particular, indole-3-acetic acid levels declined after ABA treatment in Col but not gpa1 guard cells. Consistent with this observation, the auxin antagonist α-(phenyl ethyl-2-one)-indole-3-acetic acid enhanced ABA-regulated stomatal movement and restored partial ABA sensitivity to gpa1. PMID:24368793

  8. Extraction and Characterization of Extracellular Proteins and Their Post-Translational Modifications from Arabidopsis thaliana Suspension Cell Cultures and Seedlings: A Critical Review

    Directory of Open Access Journals (Sweden)

    Mina Ghahremani

    2016-09-01

    Full Text Available Proteins secreted by plant cells into the extracellular space, consisting of the cell wall, apoplastic fluid, and rhizosphere, play crucial roles during development, nutrient acquisition, and stress acclimation. However, isolating the full range of secreted proteins has proven difficult, and new strategies are constantly evolving to increase the number of proteins that can be detected and identified. In addition, the dynamic nature of the extracellular proteome presents the further challenge of identifying and characterizing the post-translational modifications (PTMs of secreted proteins, particularly glycosylation and phosphorylation. Such PTMs are common and important regulatory modifications of proteins, playing a key role in many biological processes. This review explores the most recent methods in isolating and characterizing the plant extracellular proteome with a focus on the model plant Arabidopsis thaliana, highlighting the current challenges yet to be overcome. Moreover, the crucial role of protein PTMs in cell wall signalling, development, and plant responses to biotic and abiotic stress is discussed.

  9. Distinct UV-B and UV-A/blue light signal transduction pathways induce chalcone synthase gene expression in Arabidopsis cells

    International Nuclear Information System (INIS)

    Christie, J.M.; Jenkins, G.I.

    1996-01-01

    UV and blue light control the expression of flavonoid biosynthesis genes in a range of higher plants. To investigate the signal transduction processes involved in the induction of chalcone synthase (CHS) gene expression by UV-B and UV-A/blue light, we examined the, effects of specific agonists and inhibitors of known signaling components in mammalian systems in a photomixotrophic Arabidopsis cell suspension culture. CHS expression is induced specifically by these wavelengths in the cell culture, in a manner similar to that in mature Arabidopsis leaf tissue. Both the UV-B and UV-A/blue phototransduction processes involve calcium, although the elevation of cytosolic calcium is insufficient on its own to stimulate CHS expression. The UV-A/blue light induction of CHS expression does not appear to involve calmodulin, whereas the UV-B response does; this difference indicates that the signal transduction pathways are, at least in part, distinct. We provide evidence that both pathways involve reversible protein phosphorylation and require protein synthesis. The UV-B and UV-A/blue light signaling pathways are therefore different from the phytochrome signal transduction pathway regulating CHS expression in other species

  10. The Simbox Experiment with Arabidopsis Thaliana Cell Cultures: Hardware-Tests and First Resutls from the German-Chinese satellite Mission Shenzhou 8

    Science.gov (United States)

    Fengler, Svenja; Neef, Maren; Ecke, Margret; Hampp, Ruediger

    2013-02-01

    The Simbox experiment was the first joint German-Chinese space project. In this context Arabidopsis thaliana cell cultures were exposed to microgravity for a 17-day period. To carry out a successful space mission, diverse hardware tests were performed in advance. Due to the limited oxygen supply inside the hardware units, cells were fixed after 5 days under microgravity conditions. As a control, samples were exposed in an on-board 1g reference centrifuge. To investigate the space effect, a ground-based study was performed with the same hardware and identical experimental procedures. As we were able to obtain high quality RNA from the RNAlater quenched samples, we used the Affymetrix Arabidopsis genome array for a transcriptome analysis. Our experiment aimed at the identification of plant genes that were differentially expressed after long-term exposure to microgravity. Pair-wise comparison of flight samples with 1g controls revealed the largest differences between space 1g and ground 1g controls.

  11. A Phenotyping Method of Giant Cells from Root-Knot Nematode Feeding Sites by Confocal Microscopy Highlights a Role for CHITINASE-LIKE 1 in Arabidopsis

    Science.gov (United States)

    Cabrera, Javier; Olmo, Rocio; Ruiz-Ferrer, Virginia; Hermans, Christian; Martinez-Argudo, Isabel; Escobar, Carolina

    2018-01-01

    Most effective nematicides for the control of root-knot nematodes are banned, which demands a better understanding of the plant-nematode interaction. Understanding how gene expression in the nematode-feeding sites relates to morphological features may assist a better characterization of the interaction. However, nematode-induced galls resulting from cell-proliferation and hypertrophy hinders such observation, which would require tissue sectioning or clearing. We demonstrate that a method based on the green auto-fluorescence produced by glutaraldehyde and the tissue-clearing properties of benzyl-alcohol/benzyl-benzoate preserves the structure of the nematode-feeding sites and the plant-nematode interface with unprecedented resolution quality. This allowed us to obtain detailed measurements of the giant cells’ area in an Arabidopsis line overexpressing CHITINASE-LIKE-1 (CTL1) from optical sections by confocal microscopy, assigning a role for CTL1 and adding essential data to the scarce information of the role of gene repression in giant cells. Furthermore, subcellular structures and features of the nematodes body and tissues from thick organs formed after different biotic interactions, i.e., galls, syncytia, and nodules, were clearly distinguished without embedding or sectioning in different plant species (Arabidopsis, cucumber or Medicago). The combination of this method with molecular studies will be valuable for a better understanding of the plant-biotic interactions. PMID:29389847

  12. Cell wall targeted in planta iron accumulation enhances biomass conversion and seed iron concentration in Arabidopsis and rice

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Haibing [Center for Direct Catalytic Conversion Of Biomass to Biofuels (C3Bio), Purdue University, West Lafayette IN USA; Department of Horticulture, Purdue University, West Lafayette IN USA; Department of Biological Sciences, Purdue University, West Lafayette IN USA; Wei, Hui [Biosciences Center, National Renewable Energy Laboratory, Golden CO USA; Ma, Guojie [Center for Direct Catalytic Conversion Of Biomass to Biofuels (C3Bio), Purdue University, West Lafayette IN USA; Department of Horticulture, Purdue University, West Lafayette IN USA; Antunes, Mauricio S. [Center for Direct Catalytic Conversion Of Biomass to Biofuels (C3Bio), Purdue University, West Lafayette IN USA; Department of Biological Sciences, Purdue University, West Lafayette IN USA; Vogt, Stefan [X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne IL USA; Cox, Joseph [Center for Direct Catalytic Conversion Of Biomass to Biofuels (C3Bio), Purdue University, West Lafayette IN USA; Department of Horticulture, Purdue University, West Lafayette IN USA; Zhang, Xiao [Department of Horticulture, Purdue University, West Lafayette IN USA; Liu, Xiping [Center for Direct Catalytic Conversion Of Biomass to Biofuels (C3Bio), Purdue University, West Lafayette IN USA; Department of Horticulture, Purdue University, West Lafayette IN USA; Bu, Lintao [National Bioenergy Center, National Renewable Energy Laboratory, Golden CO USA; Gleber, S. Charlotte [X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne IL USA; Carpita, Nicholas C. [Department of Biological Sciences, Purdue University, West Lafayette IN USA; Department of Botany and Plant Pathology, Purdue University, West Lafayette IN USA; Makowski, Lee [Department of Bioengineering, Northeastern University, Boston MA USA; Department of Chemistry and Chemical Biology, Northeastern University, Boston MA USA; Himmel, Michael E. [Biosciences Center, National Renewable Energy Laboratory, Golden CO USA; Tucker, Melvin P. [X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne IL USA; McCann, Maureen C. [Center for Direct Catalytic Conversion Of Biomass to Biofuels (C3Bio), Purdue University, West Lafayette IN USA; Department of Biological Sciences, Purdue University, West Lafayette IN USA; Murphy, Angus S. [Center for Direct Catalytic Conversion Of Biomass to Biofuels (C3Bio), Purdue University, West Lafayette IN USA; Department of Horticulture, Purdue University, West Lafayette IN USA; Department of Plant Science and Landscape Architecture, University of Maryland, College Park MD USA; Peer, Wendy A. [Center for Direct Catalytic Conversion Of Biomass to Biofuels (C3Bio), Purdue University, West Lafayette IN USA; Department of Horticulture, Purdue University, West Lafayette IN USA; Department of Plant Science and Landscape Architecture, University of Maryland, College Park MD USA; Department of Environmental Science and Technology, University of Maryland, College Park MD USA

    2016-04-07

    Conversion of nongrain biomass into liquid fuel is a sustainable approach to energy demands as global population increases. Previously, we showed that iron can act as a catalyst to enhance the degradation of lignocellulosic biomass for biofuel production. However, direct addition of iron catalysts to biomass pretreatment is diffusion-limited, would increase the cost and complexity of biorefinery unit operations and may have deleterious environmental impacts. Here, we show a new strategy for in planta accumulation of iron throughout the volume of the cell wall where iron acts as a catalyst in the deconstruction of lignocellulosic biomass. We engineered CBM-IBP fusion polypeptides composed of a carbohydrate-binding module family 11 (CBM11) and an iron-binding peptide (IBP) for secretion into Arabidopsis and rice cell walls. CBM-IBP transformed Arabidopsis and rice plants show significant increases in iron accumulation and biomass conversion compared to respective controls. Further, CBM-IBP rice shows a 35% increase in seed iron concentration and a 40% increase in seed yield in greenhouse experiments. CBM-IBP rice potentially could be used to address iron deficiency, the most common and widespread nutritional disorder according to the World Health Organization.

  13. Calcium specificity signaling mechanisms in abscisic acid signal transduction in Arabidopsis guard cells

    Science.gov (United States)

    Brandt, Benjamin; Munemasa, Shintaro; Wang, Cun; Nguyen, Desiree; Yong, Taiming; Yang, Paul G; Poretsky, Elly; Belknap, Thomas F; Waadt, Rainer; Alemán, Fernando; Schroeder, Julian I

    2015-01-01

    A central question is how specificity in cellular responses to the eukaryotic second messenger Ca2+ is achieved. Plant guard cells, that form stomatal pores for gas exchange, provide a powerful system for in depth investigation of Ca2+-signaling specificity in plants. In intact guard cells, abscisic acid (ABA) enhances (primes) the Ca2+-sensitivity of downstream signaling events that result in activation of S-type anion channels during stomatal closure, providing a specificity mechanism in Ca2+-signaling. However, the underlying genetic and biochemical mechanisms remain unknown. Here we show impairment of ABA signal transduction in stomata of calcium-dependent protein kinase quadruple mutant plants. Interestingly, protein phosphatase 2Cs prevent non-specific Ca2+-signaling. Moreover, we demonstrate an unexpected interdependence of the Ca2+-dependent and Ca2+-independent ABA-signaling branches and the in planta requirement of simultaneous phosphorylation at two key phosphorylation sites in SLAC1. We identify novel mechanisms ensuring specificity and robustness within stomatal Ca2+-signaling on a cellular, genetic, and biochemical level. DOI: http://dx.doi.org/10.7554/eLife.03599.001 PMID:26192964

  14. 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.

  15. Cell polarity and patterning by PIN trafficking through early endosomal compartments in Arabidopsis thaliana.

    Directory of Open Access Journals (Sweden)

    Hirokazu Tanaka

    2013-05-01

    Full Text Available PIN-FORMED (PIN proteins localize asymmetrically at the plasma membrane and mediate intercellular polar transport of the plant hormone auxin that is crucial for a multitude of developmental processes in plants. PIN localization is under extensive control by environmental or developmental cues, but mechanisms regulating PIN localization are not fully understood. Here we show that early endosomal components ARF GEF BEN1 and newly identified Sec1/Munc18 family protein BEN2 are involved in distinct steps of early endosomal trafficking. BEN1 and BEN2 are collectively required for polar PIN localization, for their dynamic repolarization, and consequently for auxin activity gradient formation and auxin-related developmental processes including embryonic patterning, organogenesis, and vasculature venation patterning. These results show that early endosomal trafficking is crucial for cell polarity and auxin-dependent regulation of plant architecture.

  16. The Arabidopsis mutant cev1 links cell wall signaling to jasmonate and ethylene responses.

    Science.gov (United States)

    Ellis, Christine; Karafyllidis, Ioannis; Wasternack, Claus; Turner, John G

    2002-07-01

    Biotic and abiotic stresses stimulate the synthesis of jasmonates and ethylene, which, in turn, induce the expression of genes involved in stress response and enhance defense responses. The cev1 mutant has constitutive expression of stress response genes and has enhanced resistance to fungal pathogens. Here, we show that cev1 plants have increased production of jasmonate and ethylene and that its phenotype is suppressed by mutations that interrupt jasmonate and ethylene signaling. Genetic mapping, complementation analysis, and sequence analysis revealed that CEV1 is the cellulose synthase CeSA3. CEV1 was expressed predominantly in root tissues, and cev1 roots contained less cellulose than wild-type roots. Significantly, the cev1 mutant phenotype could be reproduced by treating wild-type plants with cellulose biosynthesis inhibitors, and the cellulose synthase mutant rsw1 also had constitutive expression of VSP. We propose that the cell wall can signal stress responses in plants.

  17. C-terminus-mediated voltage gating of Arabidopsis guard cell anion channel QUAC1.

    Science.gov (United States)

    Mumm, Patrick; Imes, Dennis; Martinoia, Enrico; Al-Rasheid, Khaled A S; Geiger, Dietmar; Marten, Irene; Hedrich, Rainer

    2013-09-01

    Anion transporters in plants play a fundamental role in volume regulation and signaling. Currently, two plasma membrane-located anion channel families—SLAC/SLAH and ALMT—are known. Among the ALMT family, the root-expressed ALuminium-activated Malate Transporter 1 was identified by comparison of aluminum-tolerant and Al(3+)-sensitive wheat cultivars and was subsequently shown to mediate voltage-independent malate currents. In contrast, ALMT12/QUAC1 (QUickly activating Anion Channel1) is expressed in guard cells transporting malate in an Al(3+)-insensitive and highly voltage-dependent manner. So far, no information is available about the structure and mechanism of voltage-dependent gating with the QUAC1 channel protein. Here, we analyzed gating of QUAC1-type currents in the plasma membrane of guard cells and QUAC1-expressing oocytes revealing similar voltage dependencies and activation–deactivation kinetics. In the heterologous expression system, QUAC1 was electrophysiologically characterized at increasing extra- and intracellular malate concentrations. Thereby, malate additively stimulated the voltage-dependent QUAC1 activity. In search of structural determinants of the gating process, we could not identify transmembrane domains common for voltage-sensitive channels. However, site-directed mutations and deletions at the C-terminus of QUAC1 resulted in altered voltage-dependent channel activity. Interestingly, the replacement of a single glutamate residue, which is conserved in ALMT channels from different clades, by an alanine disrupted QUAC1 activity. Together with C- and N-terminal tagging, these results indicate that the cytosolic C-terminus is involved in the voltage-dependent gating mechanism of QUAC1.

  18. Unravelling the potential of a new uracil phosphoribosyltransferase (UPRT) from Arabidopsis thaliana in sensitizing HeLa cells towards 5-fluorouracil.

    Science.gov (United States)

    Narayanan, Sharmila; Sanpui, Pallab; Sahoo, Lingaraj; Ghosh, Siddhartha Sankar

    2016-10-01

    In silico studies with uracil phosphoribosyltransferase from Arabidopsis thaliana (AtUPRT) revealed its lower binding energies for uracil and 5-fluorouracil (5-FU) as compared to those of bacterial UPRT indicating the prospective of AtUPRT in gene therapy implications. Hence, AtUPRT was cloned and stably expressed in cervical cancer cells (HeLa) to investigate the effect of prodrug 5-FU on these transfected cancer cells. The treatment of AtUPRT-expressing HeLa (HeLa-UPP) cells with 5-FU for 72h resulted in significant decrease in cell viability. Moreover, 5-FU was observed to induce apoptosis and perturb mitochondrial membrane potential in HeLa-UPP cells. While cell cycle analysis revealed significant S-phase arrest as a result of 5-FU treatment in HeLa-UPP cells, quantitative gene expression analysis demonstrated simultaneous upregulation of important cell cycle related genes, cyclin D1 and p21. The survival fractions of non-transfected, vector-transfected and AtUPRT-transfected HeLa cells, following 5-FU treatment, were calculated to be 0.425, 0.366 and 0.227, respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Arabidopsis G-protein interactome reveals connections to cell wall carbohydrates and morphogenesis.

    Science.gov (United States)

    Klopffleisch, Karsten; Phan, Nguyen; Augustin, Kelsey; Bayne, Robert S; Booker, Katherine S; Botella, Jose R; Carpita, Nicholas C; Carr, Tyrell; Chen, Jin-Gui; Cooke, Thomas Ryan; Frick-Cheng, Arwen; Friedman, Erin J; Fulk, Brandon; Hahn, Michael G; Jiang, Kun; Jorda, Lucia; Kruppe, Lydia; Liu, Chenggang; Lorek, Justine; McCann, Maureen C; Molina, Antonio; Moriyama, Etsuko N; Mukhtar, M Shahid; Mudgil, Yashwanti; Pattathil, Sivakumar; Schwarz, John; Seta, Steven; Tan, Matthew; Temp, Ulrike; Trusov, Yuri; Urano, Daisuke; Welter, Bastian; Yang, Jing; Panstruga, Ralph; Uhrig, Joachim F; Jones, Alan M

    2011-09-27

    The heterotrimeric G-protein complex is minimally composed of Gα, Gβ, and Gγ subunits. In the classic scenario, the G-protein complex is the nexus in signaling from the plasma membrane, where the heterotrimeric G-protein associates with heptahelical G-protein-coupled receptors (GPCRs), to cytoplasmic target proteins called effectors. Although a number of effectors are known in metazoans and fungi, none of these are predicted to exist in their canonical forms in plants. To identify ab initio plant G-protein effectors and scaffold proteins, we screened a set of proteins from the G-protein complex using two-hybrid complementation in yeast. After deep and exhaustive interrogation, we detected 544 interactions between 434 proteins, of which 68 highly interconnected proteins form the core G-protein interactome. Within this core, over half of the interactions comprising two-thirds of the nodes were retested and validated as genuine in planta. Co-expression analysis in combination with phenotyping of loss-of-function mutations in a set of core interactome genes revealed a novel role for G-proteins in regulating cell wall modification.

  20. Differential TOR activation and cell proliferation in Arabidopsis root and shoot apexes.

    Science.gov (United States)

    Li, Xiaojuan; Cai, Wenguo; Liu, Yanlin; Li, Hui; Fu, Liwen; Liu, Zengyu; Xu, Lin; Liu, Hongtao; Xu, Tongda; Xiong, Yan

    2017-03-07

    The developmental plasticity of plants relies on the remarkable ability of the meristems to integrate nutrient and energy availability with environmental signals. Meristems in root and shoot apexes share highly similar molecular players but are spatially separated by soil. Whether and how these two meristematic tissues have differential activation requirements for local nutrient, hormone, and environmental cues (e.g., light) remain enigmatic in photosynthetic plants. Here, we report that the activation of root and shoot apexes relies on distinct glucose and light signals. Glucose energy signaling is sufficient to activate target of rapamycin (TOR) kinase in root apexes. In contrast, both the glucose and light signals are required for TOR activation in shoot apexes. Strikingly, exogenously applied auxin is able to replace light to activate TOR in shoot apexes and promote true leaf development. A relatively low concentration of auxin in the shoot and high concentration of auxin in the root might be responsible for this distinctive light requirement in root and shoot apexes, because light is required to promote auxin biosynthesis in the shoot. Furthermore, we reveal that the small GTPase Rho-related protein 2 (ROP2) transduces light-auxin signal to activate TOR by direct interaction, which, in turn, promotes transcription factors E2Fa,b for activating cell cycle genes in shoot apexes. Consistently, constitutively activated ROP2 plants stimulate TOR in the shoot apex and cause true leaf development even without light. Together, our findings establish a pivotal hub role of TOR signaling in integrating different environmental signals to regulate distinct developmental transition and growth in the shoot and root.

  1. Reference: 398 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available modulate the photosynthetic potential of plant cells. Identification of genes required for light-induced chloroplast movement... is beginning to define the molecular machinery that controls these movement...s. In this work, we describe plastid movement impaired 2 (pmi2), a mutant in Arabidopsis (Arabi...dopsis thaliana) that displays attenuated chloroplast movements under intermediate and high light intensitie...s while maintaining a normal movement response under low light intensities. In wi

  2. Reference: 170 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available rice A et al. 2005 Mar. Plant Cell 17(3):791-803. Environmental time cues, such as photocycles (light/dark) and thermocycles...h is known about entrainment of the Arabidopsis thaliana clock to photocycles, th...e determinants of thermoperception and entrainment to thermocycles are not known. The Arabidopsis PSEUDO-RES... an oscillation after entrainment to thermocycles and to reset its clock in response to cold pulses and thus

  3. Arabidopsis ASYMMETRIC LEAVES2 protein required for leaf morphogenesis consistently forms speckles during mitosis of tobacco BY-2 cells via signals in its specific sequence.

    Science.gov (United States)

    Luo, Lilan; Ando, Sayuri; Sasabe, Michiko; Machida, Chiyoko; Kurihara, Daisuke; Higashiyama, Tetsuya; Machida, Yasunori

    2012-09-01

    Leaf primordia with high division and developmental competencies are generated around the periphery of stem cells at the shoot apex. Arabidopsis ASYMMETRIC-LEAVES2 (AS2) protein plays a key role in the regulation of many genes responsible for flat symmetric leaf formation. The AS2 gene, expressed in leaf primordia, encodes a plant-specific nuclear protein containing an AS2/LOB domain with cysteine repeats (C-motif). AS2 proteins are present in speckles in and around the nucleoli, and in the nucleoplasm of some leaf epidermal cells. We used the tobacco cultured cell line BY-2 expressing the AS2-fused yellow fluorescent protein to examine subnuclear localization of AS2 in dividing cells. AS2 mainly localized to speckles (designated AS2 bodies) in cells undergoing mitosis and distributed in a pairwise manner during the separation of sets of daughter chromosomes. Few interphase cells contained AS2 bodies. Deletion analyses showed that a short stretch of the AS2 amino-terminal sequence and the C-motif play negative and positive roles, respectively, in localizing AS2 to the bodies. These results suggest that AS2 bodies function to properly distribute AS2 to daughter cells during cell division in leaf primordia; and this process is controlled at least partially by signals encoded by the AS2 sequence itself.

  4. Changes in cytosolic pH within Arabidopsis root columella cells play a key role in the early signaling pathway for root gravitropism

    Science.gov (United States)

    Scott, A. C.; Allen, N. S.; Davies, E. (Principal Investigator)

    1999-01-01

    Ratiometric wide-field fluorescence microscopy with 1',7'- bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein (BCECF)-dextran demonstrated that gravistimulation leads to rapid changes in cytoplasmic pH (pHc) in columella cells of Arabidopsis roots. The pHc of unstimulated columella cells in tiers 2 and 3, known sites of graviperception (E.B. Blancaflor, J.B. Fasano, S. Gilroy [1998] Plant Physiol 116: 213-222), was 7.22 +/- 0.02 pH units. Following gravistimulation, the magnitude and direction of pHc changes in these cells depended on their location in the columella. Cells in the lower side of tier 2 became more alkaline by 0.4 unit within 55 s of gravistimulation, whereas alkalinization of the cells on the upper side was slower (100 s). In contrast, all cells in tier 3 acidified by 0.4 pH unit within 480 s after gravistimulation. Disrupting these pHc changes in the columella cells using pHc modifiers at concentrations that do not affect root growth altered the gravitropic response. Acidifying agents, including bafilomycin A1, enhanced curvature, whereas alkalinizing agents disrupted gravitropic bending. These results imply that pHc changes in the gravisensing cells and the resultant pH gradients across the root cap are important at an early stage in the signal cascade leading to the gravitropic response.

  5. Transcriptomic signatures of transfer cells in early developing nematode feeding cells of Arabidopsis focused on auxin and ethylene signalling.

    Directory of Open Access Journals (Sweden)

    Javier eCabrera

    2014-03-01

    Full Text Available Phyto-endoparasitic nematodes induce specialized feeding cells (NFCs in their hosts, termed syncytia and giant cells (GCs for cyst and root-knot nematodes, respectively. They differ in their ontogeny and global transcriptional signatures, but both develop cell wall ingrowths to facilitate high rates of apoplastic/symplastic solute exchange showing transfer cell (TC characteristics. Regulatory signals for TC differentiation are not still well known. The two-component signalling system (2CS and reactive oxygen species are proposed as inductors of TC identity, while, 2CSs-related genes are not major contributors to differential gene expression in early developing NFCs. Additionally, transcriptomic and functional studies have assigned a major role to auxin and ethylene as regulatory signals on early developing TCs. Genes encoding proteins with similar functions expressed in both early developing NFCs and typical TCs are putatively involved in upstream or downstream responses mediated by auxin and ethylene. Yet, no function directly associated to the TCs identity of NFCs, such as the formation of cell wall ingrowths is described for most of them. Thus we reviewed similarities between transcriptional changes observed during the early stages of NFCs formation and those described during differentiation of TCs to hypothesize about putative signals leading to TC-like differentiation of NFCs with particular emphasis on auxin an ethylene.

  6. The polyadenylation factor subunit CLEAVAGE AND POLYADENYLATION SPECIFICITY FACTOR30: A key factor of programmed cell death and a regulator of immunity in arabidopsis

    KAUST Repository

    Bruggeman, Quentin

    2014-04-04

    Programmed cell death (PCD) is essential for several aspects of plant life, including development and stress responses. Indeed, incompatible plant-pathogen interactions are well known to induce the hypersensitive response, a localized cell death. Mutational analyses have identified several key PCD components, and we recently identified the mips1 mutant of Arabidopsis (Arabidopsis thaliana), which is deficient for the key enzyme catalyzing the limiting step of myoinositol synthesis. One of the most striking features of mips1 is the light-dependent formation of lesions on leaves due to salicylic acid (SA)-dependent PCD, revealing roles for myoinositol or inositol derivatives in the regulation of PCD. Here, we identified a regulator of plant PCD by screening for mutants that display transcriptomic profiles opposing that of the mips1 mutant. Our screen identified the oxt6 mutant, which has been described previously as being tolerant to oxidative stress. In the oxt6 mutant, a transfer DNA is inserted in the CLEAVAGE AND POLYADENYLATION SPECIFICITY FACTOR30 (CPSF30) gene, which encodes a polyadenylation factor subunit homolog. We show that CPSF30 is required for lesion formation in mips1 via SA-dependent signaling, that the prodeath function of CPSF30 is not mediated by changes in the glutathione status, and that CPSF30 activity is required for Pseudomonas syringae resistance. We also show that the oxt6 mutation suppresses cell death in other lesion-mimic mutants, including lesion-simulating disease1, mitogen-activated protein kinase4, constitutive expressor of pathogenesis-related genes5, and catalase2, suggesting that CPSF30 and, thus, the control of messenger RNA 3′ end processing, through the regulation of SA production, is a key component of plant immune responses. © 2014 American Society of Plant Biologists. All rights reserved.

  7. Cell-specific vacuolar calcium storage mediated by CAX1 regulates apoplastic calcium concentration, gas exchange, and plant productivity in Arabidopsis.

    Science.gov (United States)

    Conn, Simon J; Gilliham, Matthew; Athman, Asmini; Schreiber, Andreas W; Baumann, Ute; Moller, Isabel; Cheng, Ning-Hui; Stancombe, Matthew A; Hirschi, Kendal D; Webb, Alex A R; Burton, Rachel; Kaiser, Brent N; Tyerman, Stephen D; Leigh, Roger A

    2011-01-01

    The physiological role and mechanism of nutrient storage within vacuoles of specific cell types is poorly understood. Transcript profiles from Arabidopsis thaliana leaf cells differing in calcium concentration ([Ca], epidermis 60 mM) were compared using a microarray screen and single-cell quantitative PCR. Three tonoplast-localized Ca(2+) transporters, CAX1 (Ca(2+)/H(+)-antiporter), ACA4, and ACA11 (Ca(2+)-ATPases), were identified as preferentially expressed in Ca-rich mesophyll. Analysis of respective loss-of-function mutants demonstrated that only a mutant that lacked expression of both CAX1 and CAX3, a gene ectopically expressed in leaves upon knockout of CAX1, had reduced mesophyll [Ca]. Reduced capacity for mesophyll Ca accumulation resulted in reduced cell wall extensibility, stomatal aperture, transpiration, CO(2) assimilation, and leaf growth rate; increased transcript abundance of other Ca(2+) transporter genes; altered expression of cell wall-modifying proteins, including members of the pectinmethylesterase, expansin, cellulose synthase, and polygalacturonase families; and higher pectin concentrations and thicker cell walls. We demonstrate that these phenotypes result from altered apoplastic free [Ca(2+)], which is threefold greater in cax1/cax3 than in wild-type plants. We establish CAX1 as a key regulator of apoplastic [Ca(2+)] through compartmentation into mesophyll vacuoles, a mechanism essential for optimal plant function and productivity.

  8. Circadian Stress Regimes Affect the Circadian Clock and Cause Jasmonic Acid-Dependent Cell Death in Cytokinin-Deficient Arabidopsis Plants[OPEN

    Science.gov (United States)

    Nitschke, Silvia; Cortleven, Anne; Iven, Tim; Havaux, Michel; Schmülling, Thomas

    2016-01-01

    The circadian clock helps plants measure daylength and adapt to changes in the day-night rhythm. We found that changes in the light-dark regime triggered stress responses, eventually leading to cell death, in leaves of Arabidopsis thaliana plants with reduced cytokinin levels or defective cytokinin signaling. Prolonged light treatment followed by a dark period induced stress and cell death marker genes while reducing photosynthetic efficiency. This response, called circadian stress, is also characterized by altered expression of clock and clock output genes. In particular, this treatment strongly reduced the expression of CIRCADIAN CLOCK ASSOCIATED1 (CCA1) and LATE ELONGATED HYPOCOTYL (LHY). Intriguingly, similar changes in gene expression and cell death were observed in clock mutants lacking proper CCA1 and LHY function. Circadian stress caused strong changes in reactive oxygen species- and jasmonic acid (JA)-related gene expression. The activation of the JA pathway, involving the accumulation of JA metabolites, was crucial for the induction of cell death, since the cell death phenotype was strongly reduced in the jasmonate resistant1 mutant background. We propose that adaptation to circadian stress regimes requires a normal cytokinin status which, acting primarily through the AHK3 receptor, supports circadian clock function to guard against the detrimental effects of circadian stress. PMID:27354555

  9. Chromatin dynamics in Pollen Mother Cells underpin a common scenario at the somatic-to-reproductive fate transition of both the male and female lineages in Arabidopsis

    Directory of Open Access Journals (Sweden)

    Wenjing eShe

    2015-04-01

    Full Text Available Unlike animals, where the germline is established early during embryogenesis, plants set aside their reproductive lineage late in development in dedicated floral organs. The specification of pollen mother cells (PMCs committed to meiosis takes place in the sporogenous tissue in anther locules and marks the somatic-to-reproductive cell fate transition towards the male reproductive lineage. Here we show that Arabidopsis PMCs differentiation is accompanied by large-scale changes in chromatin organization. This is characterized by significant increase in nuclear volume, chromatin decondensation, reduction in heterochromatin, eviction of linker histones and the H2AZ histone variant. These structural alterations are accompanied by dramatic, quantitative changes in histone modifications levels compared to that of surrounding somatic cells that do not share a sporogenic fate. All these changes are highly reminiscent of those we have formerly described in female megaspore mother cells (MMCs. This indicates that chromatin reprogramming is a common underlying scenario in the somatic-to-reproductive cell fate transition in both male and female lineages.

  10. MPK6 controls H2 O2-induced root elongation by mediating Ca2+ influx across the plasma membrane of root cells in Arabidopsis seedlings.

    Science.gov (United States)

    Han, Shuan; Fang, Lin; Ren, Xuejian; Wang, Wenle; Jiang, Jing

    2015-01-01

    Mitogen-activated protein kinases (MPKs) play critical roles in signalling and growth, and Ca(2+) and H2 O2 control plant growth processes associated with abscisic acid (ABA). However, it remains unclear how MPKs are involved in H2 O2 - and Ca(2+) -mediated root elongation. Root elongation in seedlings of the loss-of-function mutant Atmpk6 (Arabidopsis thaliana MPK6) was less sensitive to moderate H2 O2 or ABA than that in wild-type (WT) plants. The enhanced elongation was a result of root cell expansion. This effect disappeared when ABA-induced H2 O2 accumulation or the cytosolic Ca(2+) increase were defective. Molecular and biochemical evidence showed that increased expression of the cell wall peroxidase PRX34 in Atmpk6 root cells enhanced apoplastic H2 O2 generation; this promoted a cytosolic Ca(2+) increase and Ca(2+) influx across the plasma membrane. The plasma membrane damage caused by high levels of H2 O2 was ameliorated in a Ca(2+) -dependent manner. These results suggested that there was intensified PRX34-mediated H2 O2 generation in the apoplast and increased Ca(2+) flux into the cytosol of Atmpk6 root cells; that is, the spatial separation of apoplastic H2 O2 from cytosolic Ca(2+) in root cells prevented H2 O2 -induced inhibition of root elongation in Atmpk6 seedlings. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

  11. Arabidopsis group Ie formins localize to specific cell membrane domains, interact with actin-binding proteins and cause defects in cell expansion upon aberrant expression

    Czech Academy of Sciences Publication Activity Database

    Deeks, M.J.; Cvrčková, F.; Machesky, M. L.; Mikitova, V.; Ketelaar, T.; Žárský, Viktor; Davies, B.; Hussey, P.J.

    2005-01-01

    Roč. 168, č. 3 (2005), s. 529-540 ISSN 0028-646X R&D Projects: GA ČR GA204/02/1461; GA ČR GA204/05/0268 Institutional research plan: CEZ:AV0Z50380511 Keywords : actin * Arabidopsis * cytoskeleton Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 4.285, year: 2005

  12. Short-term exposure of Arabidopsis cell culures to hyper-G: Short-term changes in transcription regulation expression

    Science.gov (United States)

    Babbick, Maren; Hampp, Rudiger

    2005-08-01

    Callus cultures of Arabidopsis thaliana (cv. Columbia) were used to screen for early changes in gene expression in response to altered gravitational fields. In a recent microarray study we found hyper- g dependent changes in gene expression which indicated the involvement of WRKY genes [Martzivanou M. and Hampp R., Physiol. Plant., 118, 221-231,2003]. WRKY genes code for a family of plant-specific regulators of gene expression. In this study we report on the exposure of Arabidopsis callus cultures to 8g for up to 30 min. Quantitative analysis by real time RT-PCR of the amount of transcripts of WRKYs 3, 6, 22, 46, 65 and 70 showed individual changes in expression. As far as their function is known, these WRKY proteins are mainly involved in stress responses. As most alterations in transcript amount occurred within 10 min of treatment, such genes can be used for the investigation of microgravity-related effects on gene expression under sounding rocket conditions (TEXUS, MAXUS).

  13. Indole-3-butyric acid promotes adventitious rooting in Arabidopsis thaliana thin cell layers by conversion into indole-3-acetic acid and stimulation of anthranilate synthase activity.

    Science.gov (United States)

    Fattorini, L; Veloccia, A; Della Rovere, F; D'Angeli, S; Falasca, G; Altamura, M M

    2017-07-11

    Indole-3-acetic acid (IAA), and its precursor indole-3-butyric acid (IBA), control adventitious root (AR) formation in planta. Adventitious roots are also crucial for propagation via cuttings. However, IBA role(s) is/are still far to be elucidated. In Arabidopsis thaliana stem cuttings, 10 μM IBA is more AR-inductive than 10 μM IAA, and, in thin cell layers (TCLs), IBA induces ARs when combined with 0.1 μM kinetin (Kin). It is unknown whether arabidopsis TCLs produce ARs under IBA alone (10 μM) or IAA alone (10 μM), and whether they contain endogenous IAA/IBA at culture onset, possibly interfering with the exogenous IBA/IAA input. Moreover, it is unknown whether an IBA-to-IAA conversion is active in TCLs, and positively affects AR formation, possibly through the activity of the nitric oxide (NO) deriving from the conversion process. Revealed undetectable levels of both auxins at culture onset, showing that arabidopsis TCLs were optimal for investigating AR-formation under the total control of exogenous auxins. The AR-response of TCLs from various ecotypes, transgenic lines and knockout mutants was analyzed under different treatments. It was shown that ARs are better induced by IBA than IAA and IBA + Kin. IBA induced IAA-efflux (PIN1) and IAA-influx (AUX1/LAX3) genes, IAA-influx carriers activities, and expression of ANTHRANILATE SYNTHASE -alpha1 (ASA1), a gene involved in IAA-biosynthesis. ASA1 and ANTHRANILATE SYNTHASE -beta1 (ASB1), the other subunit of the same enzyme, positively affected AR-formation in the presence of exogenous IBA, because the AR-response in the TCLs of their mutant wei2wei7 was highly reduced. The AR-response of IBA-treated TCLs from ech2ibr10 mutant, blocked into IBA-to-IAA-conversion, was also strongly reduced. Nitric oxide, an IAA downstream signal and a by-product of IBA-to-IAA conversion, was early detected in IAA- and IBA-treated TCLs, but at higher levels in the latter explants. Altogether, results showed that IBA induced

  14. Control of Cell Wall Extensibility during Pollen Tube Growth

    OpenAIRE

    Hepler, Peter K.; Rounds, Caleb M.; Winship, Lawrence J.

    2013-01-01

    Tip-growing pollen tubes achieve rapid elongation while maintaining cell wall integrity by balancing local expansion, controlled by local changes in wall viscosity, against exocytosis, influenced by the activity of the actin cytoskeleton, cellular energetics, and calcium and proton physiology.

  15. Zinc tolerance and accumulation in stable cell suspension cultures and in vitro regenerated plants of the emerging model plant Arabidopsis halleri (Brassicaceae).

    Science.gov (United States)

    Vera-Estrella, Rosario; Miranda-Vergara, Maria Cristina; Barkla, Bronwyn J

    2009-03-01

    Arabidopsis halleri is increasingly employed as a model plant for studying heavy metal hyperaccumulation. With the aim of providing valuable tools for studies on cellular physiology and molecular biology of metal tolerance and transport, this study reports the development of successful and highly efficient methods for the in vitro regeneration of A. halleri plants and production of stable cell suspension lines. Plants were regenerated from leaf explants of A. halleri via a three-step procedure: callus induction, somatic embryogenesis and shoot development. Efficiency of callus proliferation and regeneration depended on the initial callus induction media and was optimal in the presence of 1 mg L(-1) 2,4-dichlorophenoxyacetic acid, and 0.05 mg L(-1) benzylaminopurine. Subsequent shoot and root regeneration from callus initiated under these conditions reached levels of 100% efficiency. High friability of the callus supported the development of cell suspension cultures with minimal cellular aggregates. Characterization of regenerated plants and cell cultures determined that they maintained not only the zinc tolerance and requirement of the whole plant but also the ability to accumulate zinc; with plants accumulating up to 50.0 micromoles zinc g(-1) FW, and cell suspension cultures 30.9 micromoles zinc g(-1) DW. Together this work will provide the experimental basis for furthering our knowledge of A. halleri as a model heavy metal hyperaccumulating plant.

  16. A novel Arabidopsis CHITIN ELICITOR RECEPTOR KINASE 1 (CERK1) mutant with enhanced pathogen-induced cell death and altered receptor processing.

    Science.gov (United States)

    Petutschnig, Elena K; Stolze, Marnie; Lipka, Ulrike; Kopischke, Michaela; Horlacher, Juliane; Valerius, Oliver; Rozhon, Wilfried; Gust, Andrea A; Kemmerling, Birgit; Poppenberger, Brigitte; Braus, Gerhard H; Nürnberger, Thorsten; Lipka, Volker

    2014-12-01

    Plants detect pathogens by sensing microbe-associated molecular patterns (MAMPs) through pattern recognition receptors. Pattern recognition receptor complexes also have roles in cell death control, but the underlying mechanisms are poorly understood. Here, we report isolation of cerk1-4, a novel mutant allele of the Arabidopsis chitin receptor CERK1 with enhanced defense responses. We identified cerk1-4 in a forward genetic screen with barley powdery mildew and consequently characterized it by pathogen assays, mutant crosses and analysis of defense pathways. CERK1 and CERK1-4 proteins were analyzed biochemically. The cerk1-4 mutation causes an amino acid exchange in the CERK1 ectodomain. Mutant plants maintain chitin signaling capacity but exhibit hyper-inducible salicylic acid concentrations and deregulated cell death upon pathogen challenge. In contrast to chitin signaling, the cerk1-4 phenotype does not require kinase activity and is conferred by the N-terminal part of the receptor. CERK1 undergoes ectodomain shedding, a well-known process in animal cell surface proteins. Wild-type plants contain the full-length CERK1 receptor protein as well as a soluble form of the CERK1 ectodomain, whereas cerk1-4 plants lack the N-terminal shedding product. Our work suggests that CERK1 may have a chitin-independent role in cell death control and is the first report of ectodomain shedding in plants. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

  17. γ-Aminobutyric acid transaminase deficiency impairs central carbon metabolism and leads to cell wall defects during salt stress in Arabidopsis roots.

    Science.gov (United States)

    Renault, Hugues; El Amrani, Abdelhak; Berger, Adeline; Mouille, Grégory; Soubigou-Taconnat, Ludivine; Bouchereau, Alain; Deleu, Carole

    2013-05-01

    Environmental constraints challenge cell homeostasis and thus require a tight regulation of metabolic activity. We have previously reported that the γ-aminobutyric acid (GABA) metabolism is crucial for Arabidopsis salt tolerance as revealed by the NaCl hypersensitivity of the GABA transaminase (GABA-T, At3g22200) gaba-t/pop2-1 mutant. In this study, we demonstrate that GABA-T deficiency during salt stress causes root and hypocotyl developmental defects and alterations of cell wall composition. A comparative genome-wide transcriptional analysis revealed that expression levels of genes involved in carbon metabolism, particularly sucrose and starch catabolism, were found to increase upon the loss of GABA-T function under salt stress conditions. Consistent with the altered mutant cell wall composition, a number of cell wall-related genes were also found differentially expressed. A targeted quantitative analysis of primary metabolites revealed that glutamate (GABA precursor) accumulated while succinate (the final product of GABA metabolism) significantly decreased in mutant roots after 1 d of NaCl treatment. Furthermore, sugar concentration was twofold reduced in gaba-t/pop2-1 mutant roots compared with wild type. Together, our results provide strong evidence that GABA metabolism is a major route for succinate production in roots and identify GABA as a major player of central carbon adjustment during salt stress. © 2012 Blackwell Publishing Ltd.

  18. Statolith Sedimentation Kinetics and Force Transduction to the Cortical Endoplasmic Reticulum in Gravity-Sensing Arabidopsis Columella Cells[W][OA

    Science.gov (United States)

    Leitz, Guenther; Kang, Byung-Ho; Schoenwaelder, Monica E.A.; Staehelin, L. Andrew

    2009-01-01

    The starch statolith hypothesis of gravity sensing in plants postulates that the sedimentation of statoliths in specialized statocytes (columella cells) provides the means for converting the gravitational potential energy into a biochemical signal. We have analyzed the sedimentation kinetics of statoliths in the central S2 columella cells of Arabidopsis thaliana. The statoliths can form compact aggregates with gap sizes between statoliths approaching sedimentation phase, the statoliths tend to move at a distance to the cortical endoplasmic reticulum (ER) boundary and interact only transiently with the ER. Statoliths moved by laser tweezers against the ER boundary experience an elastic lift force upon release from the optical trap. High-resolution electron tomography analysis of statolith-to-ER contact sites indicate that the weight of statoliths is sufficient to locally deform the ER membranes that can potentially activate mechanosensitive ion channels. We suggest that in root columella cells, the transduction of the kinetic energy of sedimenting statoliths into a biochemical signal involves a combination of statolith-driven motion of the cytosol, statolith-induced deformation of the ER membranes, and a rapid release of kinetic energy from the ER during reorientation to activate mechanosensitive sites within the central columella cells. PMID:19276442

  19. Plant-specific Histone Deacetylases HDT½ Regulate GIBBERELLIN 2-OXIDASE 2 Expression to Control Arabidopsis Root Meristem Cell Number

    KAUST Repository

    Li, Huchen; Torres-Garcia, Jesus; latrasse, David; Benhamed, Moussa; Schilderink, Stefan; Zhou, Wenkun; Kulikova, Olga; Hirt, Heribert; Bisseling, Ton

    2017-01-01

    Root growth is modulated by environmental factors and depends on cell production in the root meristem (RM). New cells in the meristem are generated by stem cells and transit-amplifying cells, which together determine RM cell number. Transcription

  20. SUV2, which encodes an ATR-related cell cycle checkpoint and putative plant ATRIP, is required for aluminium-dependent root growth inhibition in Arabidopsis.

    Science.gov (United States)

    Sjogren, Caroline A; Larsen, Paul B

    2017-09-01

    A suppressor mutagenesis screen was conducted in order to identify second site mutations that could reverse the extreme hypersensitivity to aluminium (Al) seen for the Arabidopsis mutant, als3-1. From this screen, it was found that a loss-of-function mutation in the previously described SUV2 (SENSITIVE TO UV 2), which encodes a putative plant ATRIP homologue that is a component of the ATR-dependent cell checkpoint response, reversed the als3-1 phenotype. This included prevention of hallmarks associated with als3-1 including Al-dependent terminal differentiation of the root tip and transition to endoreduplication. From this analysis, SUV2 was determined to be required for halting cell cycle progression and triggering loss of the quiescent centre (QC) following exposure to Al. In conjunction with this, SUV2 was found to have a similar role as ATR, ALT2 and SOG1 in Al-dependent stoppage of root growth, all of which are required for promotion of expression of a suite of genes that likely are part of an Al-dependent DNA damage transcriptional response. This work argues that these Al response factors work together to detect Al-dependent damage and subsequently activate a DNA damage response pathway that halts the cell cycle and subsequently promotes QC differentiation and entrance into endocycling. © 2017 John Wiley & Sons Ltd.

  1. The Cysteine Protease CEP1, a Key Executor Involved in Tapetal Programmed Cell Death, Regulates Pollen Development in Arabidopsis[W][OPEN

    Science.gov (United States)

    Zhang, Dandan; Liu, Di; Lv, Xiaomeng; Wang, Ying; Xun, Zhili; Liu, Zhixiong; Li, Fenglan; Lu, Hai

    2014-01-01

    Tapetal programmed cell death (PCD) is a prerequisite for pollen grain development in angiosperms, and cysteine proteases are the most ubiquitous hydrolases involved in plant PCD. We identified a papain-like cysteine protease, CEP1, which is involved in tapetal PCD and pollen development in Arabidopsis thaliana. CEP1 is expressed specifically in the tapetum from stages 5 to 11 of anther development. The CEP1 protein first appears as a proenzyme in precursor protease vesicles and is then transported to the vacuole and transformed into the mature enzyme before rupture of the vacuole. cep1 mutants exhibited aborted tapetal PCD and decreased pollen fertility with abnormal pollen exine. A transcriptomic analysis revealed that 872 genes showed significantly altered expression in the cep1 mutants, and most of them are important for tapetal cell wall organization, tapetal secretory structure formation, and pollen development. CEP1 overexpression caused premature tapetal PCD and pollen infertility. ELISA and quantitative RT-PCR analyses confirmed that the CEP1 expression level showed a strong relationship to the degree of tapetal PCD and pollen fertility. Our results reveal that CEP1 is a crucial executor during tapetal PCD and that proper CEP1 expression is necessary for timely degeneration of tapetal cells and functional pollen formation. PMID:25035401

  2. Expression analysis of cell wall assembly and remodelling-related genes in Arabidopsis roots subjected to boron stress and brassinosteroid at different developmental stages

    Directory of Open Access Journals (Sweden)

    Rabia İşkil

    2018-04-01

    Full Text Available ABSTRACT Plant cell walls are affected by many biotic and abiotic stress conditions. The aim of this study is to determine the effects of 24-Epibrassinolide (EBL on some cell wall-related genes in root tissue of five- and ten-week-old Arabidopsis thaliana plants exposed to boron (B deficiency (0 µM or toxicity (3000 µM at the transcriptional level. Expressions of the genes that encode cellulose synthase (CESA1, CESA4, CESA6 and CESA8, cellulose synthase-like (CSLB5, expansin (EXPA5, EXPA8 and EXPA14 and cell wall protein (SEB1 decreased under conditions of B deficiency and toxicity. EBL treatments, in general, led the expressions of these genes to reduce significantly. Expressions of xyloglucan endotransglucosylase/hydrolase genes (XTH21 and XTH23 changed only under conditions of B toxicity. Boron stress and/or EBL treatments caused different responses in expression of pectin methylesterase (PME2 and PME41 genes. As a result of B stress, the expression levels of investigated genes changed more in roots of five-week-old plants than in roots of ten-week-old plants. Results of the present study include new findings that support the ability of BRs to increase molecular aspects of tolerance to stress in plants.

  3. High-resolution confocal imaging of wall ingrowth deposition in plant transfer cells: Semi-quantitative analysis of phloem parenchyma transfer cell development in leaf minor veins of Arabidopsis.

    Science.gov (United States)

    Nguyen, Suong T T; McCurdy, David W

    2015-04-23

    Transfer cells (TCs) are trans-differentiated versions of existing cell types designed to facilitate enhanced membrane transport of nutrients at symplasmic/apoplasmic interfaces. This transport capacity is conferred by intricate wall ingrowths deposited secondarily on the inner face of the primary cell wall, hence promoting the potential trans-membrane flux of solutes and consequently assigning TCs as having key roles in plant growth and productivity. However, TCs are typically positioned deep within tissues and have been studied mostly by electron microscopy. Recent advances in fluorophore labelling of plant cell walls using a modified pseudo-Schiff-propidium iodide (mPS-PI) staining procedure in combination with high-resolution confocal microscopy have allowed visualization of cellular details of individual tissue layers in whole mounts, hence enabling study of tissue and cellular architecture without the need for tissue sectioning. Here we apply a simplified version of the mPS-PI procedure for confocal imaging of cellulose-enriched wall ingrowths in vascular TCs at the whole tissue level. The simplified mPS-PI staining procedure produced high-resolution three-dimensional images of individual cell types in vascular bundles and, importantly, wall ingrowths in phloem parenchyma (PP) TCs in minor veins of Arabidopsis leaves and companion cell TCs in pea. More efficient staining of tissues was obtained by replacing complex clearing procedures with a simple post-fixation bleaching step. We used this modified procedure to survey the presence of PP TCs in other tissues of Arabidopsis including cotyledons, cauline leaves and sepals. This high-resolution imaging enabled us to classify different stages of wall ingrowth development in Arabidopsis leaves, hence enabling semi-quantitative assessment of the extent of wall ingrowth deposition in PP TCs at the whole leaf level. Finally, we conducted a defoliation experiment as an example of using this approach to statistically

  4. Interaction between the moss Physcomitrella patens and Phytophthora : a novel pathosystem for live-cell imaging of subcellular defence

    NARCIS (Netherlands)

    Overdijk, Elysa J R; DE Keijzer, Jeroen; DE Groot, Deborah; Schoina, Charikleia; Bouwmeester, K.; Ketelaar, Tijs; Govers, Francine

    Live-cell imaging of plant-pathogen interactions is often hampered by the tissue complexity and multicell layered nature of the host. Here, we established a novel pathosystem with the moss Physcomitrella patens as host for Phytophthora. The tip-growing protonema cells of this moss are ideal for

  5. Expression of transcription factors after short-term exposure of Arabidopsis thaliana cell cultures to hypergravity and simulated microgravity (2-D/3-D clinorotation, magnetic levitation)

    Science.gov (United States)

    Babbick, M.; Dijkstra, C.; Larkin, O. J.; Anthony, P.; Davey, M. R.; Power, J. B.; Lowe, K. C.; Cogoli-Greuter, M.; Hampp, R.

    Gravity is an important environmental factor that controls plant growth and development. Studies have shown that the perception of gravity is not only a property of specialized cells, but can also be performed by undifferentiated cultured cells. In this investigation, callus of Arabidopsis thaliana cv. Columbia was used to investigate the initial steps of gravity-related signalling cascades, through altered expression of transcription factors (TFs). TFs are families of small proteins that regulate gene expression by binding to specific promoter sequences. Based on microarray studies, members of the gene families WRKY, MADS-box, MYB, and AP2/EREBP were selected for investigation, as well as members of signalling chains, namely IAA 19 and phosphoinositol-4-kinase. Using qRT-PCR, transcripts were quantified within a period of 30 min in response to hypergravity (8 g), clinorotation [2-D clinostat and 3-D random positioning machine (RPM)] and magnetic levitation (ML). The data indicated that (1) changes in gravity induced stress-related signalling, and (2) exposure in the RPM induced changes in gene expression which resemble those of magnetic levitation. Two dimensional clinorotation resulted in responses similar to those caused by hypergravity. It is suggested that RPM and ML are preferable to simulate microgravity than clinorotation.

  6. Manipulation of Guaiacyl and Syringyl Monomer Biosynthesis in an Arabidopsis Cinnamyl Alcohol Dehydrogenase Mutant Results in Atypical Lignin Biosynthesis and Modified Cell Wall Structure

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Nickolas A.; Tobimatsu, Yuki; Ciesielski, Peter N.; Ximenes, Eduardo; Ralph, John; Donohoe, Bryon S.; Ladisch, Michael; Chapple, Clint

    2015-08-01

    Modifying lignin composition and structure is a key strategy to increase plant cell wall digestibility for biofuel production. Disruption of the genes encoding both cinnamyl alcohol dehydrogenases (CADs), including CADC and CADD, in Arabidopsis thaliana results in the atypical incorporation of hydroxycinnamaldehydes into lignin. Another strategy to change lignin composition is downregulation or overexpression of ferulate 5-hydroxylase (F5H), which results in lignins enriched in guaiacyl or syringyl units, respectively. Here, we combined these approaches to generate plants enriched in coniferaldehyde-derived lignin units or lignins derived primarily from sinapaldehyde. The cadc cadd and ferulic acid hydroxylase1 (fah1) cadc cadd plants are similar in growth to wild-type plants even though their lignin compositions are drastically altered. In contrast, disruption of CAD in the F5H-overexpressing background results in dwarfism. The dwarfed phenotype observed in these plants does not appear to be related to collapsed xylem, a hallmark of many other lignin-deficient dwarf mutants. cadc cadd, fah1 cadc cadd, and cadd F5H-overexpressing plants have increased enzyme-catalyzed cell wall digestibility. Given that these CAD-deficient plants have similar total lignin contents and only differ in the amounts of hydroxycinnamaldehyde monomer incorporation, these results suggest that hydroxycinnamaldehyde content is a more important determinant of digestibility than lignin content.

  7. A R2R3-MYB transcription factor that is specifically expressed in cotton (Gossypium hirsutum) fibers affects secondary cell wall biosynthesis and deposition in transgenic Arabidopsis.

    Science.gov (United States)

    Sun, Xiang; Gong, Si-Ying; Nie, Xiao-Ying; Li, Yang; Li, Wen; Huang, Geng-Qing; Li, Xue-Bao

    2015-07-01

    Secondary cell wall (SCW) is an important industrial raw material for pulping, papermaking, construction, lumbering, textiles and potentially for biofuel production. The process of SCW thickening of cotton fibers lays down the cellulose that will constitute the bulk (up to 96%) of the fiber at maturity. In this study, a gene encoding a MYB-domain protein was identified in cotton (Gossypium hirsutum) and designated as GhMYBL1. Quantitative real-time polymerase chain reaction (RT-PCR) analysis revealed that GhMYBL1 was specifically expressed in cotton fibers at the stage of secondary wall deposition. Further analysis indicated that this protein is a R2R3-MYB transcription factor, and is targeted to the cell nucleus. Overexpression of GhMYBL1 in Arabidopsis affected the formation of SCW in the stem xylem of the transgenic plants. The enhanced SCW thickening also occurred in the interfascicular fibers, xylary fibers and vessels of the GhMYBL1-overexpression transgenic plants. The expression of secondary wall-associated genes, such as CesA4, CesA7, CesA8, PAL1, F5H and 4CL1, were upregulated, and consequently, cellulose and lignin biosynthesis were enhanced in the GhMYBL1 transgenic plants. These data suggested that GhMYBL1 may participate in modulating the process of secondary wall biosynthesis and deposition of cotton fibers. © 2014 Scandinavian Plant Physiology Society.

  8. Manipulation of Guaiacyl and Syringyl Monomer Biosynthesis in an Arabidopsis Cinnamyl Alcohol Dehydrogenase Mutant Results in Atypical Lignin Biosynthesis and Modified Cell Wall Structure.

    Science.gov (United States)

    Anderson, Nickolas A; Tobimatsu, Yuki; Ciesielski, Peter N; Ximenes, Eduardo; Ralph, John; Donohoe, Bryon S; Ladisch, Michael; Chapple, Clint

    2015-08-01

    Modifying lignin composition and structure is a key strategy to increase plant cell wall digestibility for biofuel production. Disruption of the genes encoding both cinnamyl alcohol dehydrogenases (CADs), including CADC and CADD, in Arabidopsis thaliana results in the atypical incorporation of hydroxycinnamaldehydes into lignin. Another strategy to change lignin composition is downregulation or overexpression of ferulate 5-hydroxylase (F5H), which results in lignins enriched in guaiacyl or syringyl units, respectively. Here, we combined these approaches to generate plants enriched in coniferaldehyde-derived lignin units or lignins derived primarily from sinapaldehyde. The cadc cadd and ferulic acid hydroxylase1 (fah1) cadc cadd plants are similar in growth to wild-type plants even though their lignin compositions are drastically altered. In contrast, disruption of CAD in the F5H-overexpressing background results in dwarfism. The dwarfed phenotype observed in these plants does not appear to be related to collapsed xylem, a hallmark of many other lignin-deficient dwarf mutants. cadc cadd, fah1 cadc cadd, and cadd F5H-overexpressing plants have increased enzyme-catalyzed cell wall digestibility. Given that these CAD-deficient plants have similar total lignin contents and only differ in the amounts of hydroxycinnamaldehyde monomer incorporation, these results suggest that hydroxycinnamaldehyde content is a more important determinant of digestibility than lignin content. © 2015 American Society of Plant Biologists. All rights reserved.

  9. The Hidden Geometries of the Arabidopsis thaliana Epidermis

    KAUST Repository

    Staff, Lee; Hurd, Patricia; Reale, Lara; Seoighe, Cathal; Rockwood, Alyn; Gehring, Christoph A

    2012-01-01

    The quest for the discovery of mathematical principles that underlie biological phenomena is ancient and ongoing. We present a geometric analysis of the complex interdigitated pavement cells in the Arabidopsis thaliana (Col.) adaxial epidermis

  10. A Transcriptomic Analysis of Xylan Mutants Does Not Support the Existence of a Secondary Cell Wall Integrity System in Arabidopsis.

    Science.gov (United States)

    Faria-Blanc, Nuno; Mortimer, Jenny C; Dupree, Paul

    2018-01-01

    Yeast have long been known to possess a cell wall integrity (CWI) system, and recently an analogous system has been described for the primary walls of plants (PCWI) that leads to changes in plant growth and cell wall composition. A similar system has been proposed to exist for secondary cell walls (SCWI). However, there is little data to support this. Here, we analyzed the stem transcriptome of a set of cell wall biosynthetic mutants in order to investigate whether cell wall damage, in this case caused by aberrant xylan synthesis, activates a signaling cascade or changes in cell wall synthesis gene expression. Our data revealed remarkably few changes to the transcriptome. We hypothesize that this is because cells undergoing secondary cell wall thickening have entered a committed programme leading to cell death, and therefore a SCWI system would have limited impact. The absence of transcriptomic responses to secondary cell wall alterations may facilitate engineering of the secondary cell wall of plants.

  11. Patterning and lifetime of plasma membrane-localized cellulose synthase is dependent on actin organization in Arabidopsis interphase cells

    NARCIS (Netherlands)

    Sampathkumar, A.; Gutierrez, R.; McFarlane, H.E.; Bringmann, M.; Lindeboom, J.J.; Emons, A.M.C.; Samuels, L.; Ketelaar, T.; Ehrhardt, D.W.; Persson, S.

    2013-01-01

    The actin and microtubule cytoskeletons regulate cell shape across phyla, from bacteria to metazoans. In organisms with cell walls, the wall acts as a primary constraint of shape, and generation of specific cell shape depends on cytoskeletal organization for wall deposition and/or cell expansion. In

  12. An auxin transport independent pathway is involved in phosphate stress-induced root architectural alterations in Arabidopsis. Identification of BIG as a mediator of auxin in pericycle cell activation.

    Science.gov (United States)

    López-Bucio, José; Hernández-Abreu, Esmeralda; Sánchez-Calderón, Lenin; Pérez-Torres, Anahí; Rampey, Rebekah A; Bartel, Bonnie; Herrera-Estrella, Luis

    2005-02-01

    Arabidopsis (Arabidopsis thaliana) plants display a number of root developmental responses to low phosphate availability, including primary root growth inhibition, greater formation of lateral roots, and increased root hair elongation. To gain insight into the regulatory mechanisms by which phosphorus (P) availability alters postembryonic root development, we performed a mutant screen to identify genetic determinants involved in the response to P deprivation. Three low phosphate-resistant root lines (lpr1-1 to lpr1-3) were isolated because of their reduced lateral root formation in low P conditions. Genetic and molecular analyses revealed that all lpr1 mutants were allelic to BIG, which is required for normal auxin transport in Arabidopsis. Detailed characterization of lateral root primordia (LRP) development in wild-type and lpr1 mutants revealed that BIG is required for pericycle cell activation to form LRP in both high (1 mm) and low (1 microm) P conditions, but not for the low P-induced alterations in primary root growth, lateral root emergence, and root hair elongation. Exogenously supplied auxin restored normal lateral root formation in lpr1 mutants in the two P treatments. Treatment of wild-type Arabidopsis seedlings with brefeldin A, a fungal metabolite that blocks auxin transport, phenocopies the root developmental alterations observed in lpr1 mutants in both high and low P conditions, suggesting that BIG participates in vesicular targeting of auxin transporters. Taken together, our results show that auxin transport and BIG function have fundamental roles in pericycle cell activation to form LRP and promote root hair elongation. The mechanism that activates root system architectural alterations in response to P deprivation, however, seems to be independent of auxin transport and BIG.

  13. Divergent regulation of Arabidopsis SAUR genes

    NARCIS (Netherlands)

    Mourik, van Hilda; Dijk, van Aalt D.J.; Stortenbeker, Niek; Angenent, Gerco C.; Bemer, Marian

    2017-01-01

    Background: Small Auxin-Upregulated RNA (SAUR) genes encode growth regulators that induce cell elongation. Arabidopsis contains more than 70 SAUR genes, of which the growth-promoting function has been unveiled in seedlings, while their role in other tissues remained largely unknown. Here, we

  14. Reference: 359 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available 359 http://metadb.riken.jp/db/SciNetS_ria224i/cria224u4ria224u16531491i Cnops Gerda...leaf development in Arabidopsis thaliana. 4 852-66 16531491 2006 Apr The Plant cell Azmi Abdelkrim|Cnops Gerda

  15. Reference: 749 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available former mutant had decreased electron transport rates, a lower DeltapH gradient across the grana membranes, r...the PSII particles of these plants were organized in unusual two-dimensional arrays in the grana membranes. ...d the electron transport rate in grana membranes of Arabidopsis. 4 1012-28 18381925 2008 Apr The Plant cell

  16. Reference: 223 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available 223 http://metadb.riken.jp/db/SciNetS_ria224i/cria224u4ria224u15923347i Dohmann Es... cause the cop/det/fus mutant phenotype in Arabidopsis. 7 1967-78 15923347 2005 Jul The Plant cell Dohmann Esther M N|Kuhnle Carola|Schwechheimer Claus

  17. Polarized localization and borate-dependent degradation of the Arabidopsis borate transporter BOR1 in tobacco BY-2 cells [v1; ref status: indexed, http://f1000r.es/kv

    Directory of Open Access Journals (Sweden)

    Noboru Yamauchi

    2013-09-01

    Full Text Available In Arabidopsis the borate transporter BOR1, which is located in the plasma membrane, is degraded in the presence of excess boron by an endocytosis-mediated mechanism. A similar mechanism was suggested in rice as excess boron decreased rice borate transporter levels, although in this case whether the decrease was dependent on an increase in degradation or a decrease in protein synthesis was not elucidated. To address whether the borate-dependent degradation mechanism is conserved among plant cells, we analyzed the fate of GFP-tagged BOR1 (BOR1-GFP in transformed tobacco BY-2 cells. Cells expressing BOR1-GFP displayed GFP fluorescence at the plasma membrane, especially at the membrane between two attached cells. The plasma membrane signal was abolished when cells were incubated in medium with a high concentration of borate (3 to 5 mM. This decrease in BOR1-GFP signal was mediated by a specific degradation of the protein after internalization by endocytosis from the plasma membrane. Pharmacological analysis indicated that the decrease in BOR1-GFP largely depends on the increase in degradation rate and that the degradation was mediated by a tyrosine-motif and the actin cytoskeleton. Tyr mutants of BOR1-GFP, which has been shown to inhibit borate-dependent degradation in Arabidopsis root cells, did not show borate-dependent endocytosis in tobacco BY-2 cells. These findings indicate that the borate-dependent degradation machinery of the borate transporter is conserved among plant species.

  18. Expression of transcription factors after short-term exposure of Arabidopsis thaliana cell cultures to hyper-g, and to simulated and sounding rocket micro-g

    Science.gov (United States)

    Hampp, R.; Babbick, M.

    Previous microarray studies with cell cultures of Arabidopsis thaliana cv Columbia have shown responses in gene expression which were partly specific to exposure to microgravity sounding rocket experiment TEXUS In order to get access to early responses upon changes in gravitational fields we used exposure times as short as 2 min For this purpose we selected a range of genes which code for different groups of transcription factors WRKY ERF MYB MADS Samples were taken in 5-min clinorotation 2- and 3-dimensional hypergravity 8g and 2-min intervals sounding rocket experiment Amounts of transcripts were determined by quantitative RT PCR Most transcripts showed a significant transient change in content within a time frame of up to 30 min after changing the external gravitational field strength They could be grouped into 1 basic stress responses which occurred under all conditions 2 clinorotation-related effects which were either identical or opposite between 2D 60 rpm 4x10 -2 g and 3D clinorotation random positioning machine and 3 alterations specific to the microgravity exposure under sounding rocket conditions MAXUS The data are discussed in relation to gravitation-dependent signalling chains and with regard to the simulation of microgravity by means of clinorotation Supported by a grant from the Deutsches Zentrum f u r Luft- und Raumfahrt e V grant no 50 WB 0143

  19. Cytosolic Calcium, hydrogen peroxide, and related gene expression and protein modulation in Arabidopsis thaliana cell cultures respond immediately to altered gravitation: Parabolic flight data

    Science.gov (United States)

    Hampp, Ruediger; Hausmann, Niklas; Neef, Maren; Fengler, Svenja

    Callus cell cultures of Arabidopsis thaliana (cv. Columbia) were exposed to parabolic flights in order to assess molecular short-term responses to altered gravity fields. Using transgenic cell lines, hydrogen peroxide and cytosolic Ca2+ were continuously monitored. In parallel, the metabolism of samples was chemically quenched (RNAlater, Ambion, for RNA; acid/base for NADPH, NADP) at typical stages of a parabola (1g before pull up; end of pull up (1.8 g), end of microgravity (µg, 20 sec), and end of pull out (1.8 g)). Cells exhibited an increase of both Ca2+ and hydrogen peroxide with the onset of µg, and a decline thereafter. This behaviour was accompanied by a decrease of the NADPH/NADP redox ratio, indicating a Ca2+-dependent activation of a NADPH oxidase. Microarray analyses revealed concomitant expression profiles. At the end of the microgravity phase, 396 transcripts were specifically up-, while 485 were down-regulated. Up-regulation was dominated by Ca2+- and ROS(reactive oxygen species)-related gene products. The same material was also used for the analysis of phosphopeptides by 2D SDS PAGE. Relevant spots were identified by liquid chromatography-MS. With the exception of a chaperone (HSP 70-3), hypergravity (1.8 g) and microgravity modified different sets of proteins. These are partly involved in primary metabolism (glycolysis, gluconeogenesis, citrate cycle) and detoxification of reactive oxygen species. Taken together, these data show that both gene expression and protein modulation jointly respond within seconds to alterations in the gravity field, with a focus on metabolic adaptation, signalling and control of ROS.

  20. Dehydration induced loss of photosynthesis in Arabidopsis leaves during senescence is accompanied by the reversible enhancement in the activity of cell wall β-glucosidase.

    Science.gov (United States)

    Patro, Lichita; Mohapatra, Pranab Kishor; Biswal, Udaya Chand; Biswal, Basanti

    2014-08-01

    The physiology of loss of photosynthetic production of sugar and the consequent cellular sugar reprogramming during senescence of leaves experiencing environmental stress largely remains unclear. We have shown that leaf senescence in Arabidopsis thaliana causes a significant reduction in the rate of oxygen evolution and net photosynthetic rate (Pn). The decline in photosynthesis is further aggravated by dehydration. During dehydration, primary photochemical reaction of thylakoids and net photosynthesis decrease in parallel with the increase in water deficit. Senescence induced loss in photosynthesis is accompanied by a significant increase in the activity of cell wall hydrolyzing enzyme such as β-glucosidase associated with cell wall catabolism. The activity of this enzyme is further enhanced when the senescing leaves experience dehydration stress. It is possible that both senescence and stress separately or in combination result in the loss in photosynthesis which could be a signal for an enhancement in the activity of β-glucosidase that breaks down cell wall polysaccharides to sugar to sustain respiration for metabolic activities of plants experiencing stress. Thus dehydration response of cell wall hydrolases of senescing leaves is considered as plants' strategy to have cell wall polysaccharides as an alternative energy source for completion of energy requiring senescence process, stress survival and maintenance of recovery potential of energy deficit cells in the background of loss in photosynthesis. Withdrawal of stress (rehydration) distinctly exhibits recovery of photosynthesis and suppression of enzyme activity. Retention of the signaling for sugar reprogramming through breakdown of cell wall polysaccharides in the senescing leaves exposed to severe drought stress suggests that senescing leaves like mature ones possess potential for stress recovery. The precise mechanism of stress adaptation of senescing leaves is yet to be known. A significant

  1. Control of Anther Cell Differentiation by the Small Protein Ligand TPD1 and Its Receptor EMS1 in Arabidopsis.

    Directory of Open Access Journals (Sweden)

    Jian Huang

    2016-08-01

    Full Text Available A fundamental feature of sexual reproduction in plants and animals is the specification of reproductive cells that conduct meiosis to form gametes, and the associated somatic cells that provide nutrition and developmental cues to ensure successful gamete production. The anther, which is the male reproductive organ in seed plants, produces reproductive microsporocytes (pollen mother cells and surrounding somatic cells. The microsporocytes yield pollen via meiosis, and the somatic cells, particularly the tapetum, are required for the normal development of pollen. It is not known how the reproductive cells affect the differentiation of these somatic cells, and vice versa. Here, we use molecular genetics, cell biological, and biochemical approaches to demonstrate that TPD1 (TAPETUM DETERMINANT1 is a small secreted cysteine-rich protein ligand that interacts with the LRR (Leucine-Rich Repeat domain of the EMS1 (EXCESS MICROSPOROCYTES1 receptor kinase at two sites. Analyses of the expressions and localizations of TPD1 and EMS1, ectopic expression of TPD1, experimental missorting of TPD1, and ablation of microsporocytes yielded results suggesting that the precursors of microsporocyte/microsporocyte-derived TPD1 and pre-tapetal-cell-localized EMS1 initially promote the periclinal division of secondary parietal cells and then determine one of the two daughter cells as a functional tapetal cell. Our results also indicate that tapetal cells suppress microsporocyte proliferation. Collectively, our findings show that tapetal cell differentiation requires reproductive-cell-secreted TPD1, illuminating a novel mechanism whereby signals from reproductive cells determine somatic cell fate in plant sexual reproduction.

  2. COBRA-LIKE2, a Member of the Glycosylphosphatidylinositol-Anchored COBRA-LIKE Family, Plays a Role in Cellulose Deposition in Arabidopsis Seed Coat Mucilage Secretory Cells1,2[OPEN

    Science.gov (United States)

    Ben-Tov, Daniela; Abraham, Yael; Stav, Shira; Thompson, Kevin; Loraine, Ann; Elbaum, Rivka; de Souza, Amancio; Pauly, Markus; Kieber, Joseph J.; Harpaz-Saad, Smadar

    2015-01-01

    Differentiation of the maternally derived seed coat epidermal cells into mucilage secretory cells is a common adaptation in angiosperms. Recent studies identified cellulose as an important component of seed mucilage in various species. Cellulose is deposited as a set of rays that radiate from the seed upon mucilage extrusion, serving to anchor the pectic component of seed mucilage to the seed surface. Using transcriptome data encompassing the course of seed development, we identified COBRA-LIKE2 (COBL2), a member of the glycosylphosphatidylinositol-anchored COBRA-LIKE gene family in Arabidopsis (Arabidopsis thaliana), as coexpressed with other genes involved in cellulose deposition in mucilage secretory cells. Disruption of the COBL2 gene results in substantial reduction in the rays of cellulose present in seed mucilage, along with an increased solubility of the pectic component of the mucilage. Light birefringence demonstrates a substantial decrease in crystalline cellulose deposition into the cellulosic rays of the cobl2 mutants. Moreover, crystalline cellulose deposition into the radial cell walls and the columella appears substantially compromised, as demonstrated by scanning electron microscopy and in situ quantification of light birefringence. Overall, the cobl2 mutants display about 40% reduction in whole-seed crystalline cellulose content compared with the wild type. These data establish that COBL2 plays a role in the deposition of crystalline cellulose into various secondary cell wall structures during seed coat epidermal cell differentiation. PMID:25583925

  3. The Arabidopsis arc5 and arc6 mutations differentially affect plastid morphology in pavement and guard cells in the leaf epidermis.

    Science.gov (United States)

    Fujiwara, Makoto T; Yasuzawa, Mana; Kojo, Kei H; Niwa, Yasuo; Abe, Tomoko; Yoshida, Shigeo; Nakano, Takeshi; Itoh, Ryuuichi D

    2018-01-01

    Chloroplasts, or photosynthetic plastids, multiply by binary fission, forming a homogeneous population in plant cells. In Arabidopsis thaliana, the division apparatus (or division ring) of mesophyll chloroplasts includes an inner envelope transmembrane protein ARC6, a cytoplasmic dynamin-related protein ARC5 (DRP5B), and members of the FtsZ1 and FtsZ2 families of proteins, which co-assemble in the stromal mid-plastid division ring (FtsZ ring). FtsZ ring placement is controlled by several proteins, including a stromal factor MinE (AtMinE1). During leaf mesophyll development, ARC6 and AtMinE1 are necessary for FtsZ ring formation and thus plastid division initiation, while ARC5 is essential for a later stage of plastid division. Here, we examined plastid morphology in leaf epidermal pavement cells (PCs) and stomatal guard cells (GCs) in the arc5 and arc6 mutants using stroma-targeted fluorescent proteins. The arc5 PC plastids were generally a bit larger than those of the wild type, but most had normal shapes and were division-competent, unlike mutant mesophyll chloroplasts. The arc6 PC plastids were heterogeneous in size and shape, including the formation of giant and mini-plastids, plastids with highly developed stromules, and grape-like plastid clusters, which varied on a cell-by-cell basis. Moreover, unique plastid phenotypes for stomatal GCs were observed in both mutants. The arc5 GCs rarely lacked chlorophyll-bearing plastids (chloroplasts), while they accumulated minute chlorophyll-less plastids, whereas most GCs developed wild type-like chloroplasts. The arc6 GCs produced large chloroplasts and/or chlorophyll-less plastids, as previously observed, but unexpectedly, their chloroplasts/plastids exhibited marked morphological variations. We quantitatively analyzed plastid morphology and partitioning in paired GCs from wild-type, arc5, arc6, and atminE1 plants. Collectively, our results support the notion that ARC5 is dispensable in the process of equal division

  4. Responses of transgenic Arabidopsis plants and recombinant yeast cells expressing a novel durum wheat manganese superoxide dismutase TdMnSOD to various abiotic stresses.

    Science.gov (United States)

    Kaouthar, Feki; Ameny, Farhat-Khemakhem; Yosra, Kamoun; Walid, Saibi; Ali, Gargouri; Faiçal, Brini

    2016-07-01

    In plant cells, the manganese superoxide dismutase (Mn-SOD) plays an elusive role in the response to oxidative stress. In this study, we describe the isolation and functional characterization of a novel Mn-SOD from durum wheat (Triticum turgidum L. subsp. Durum), named TdMnSOD. Molecular phylogeny analysis showed that the durum TdMnSOD exhibited high amino acids sequence identity with other Mn-SOD plants. The three-dimensional structure showed that TdMnSOD forms a homotetramer and each subunit is composed of a predominantly α-helical N-terminal domain and a mixed α/β C-terminal domain. TdMnSOD gene expression analysis showed that this gene was induced by various abiotic stresses in durum wheat. The expression of TdMnSOD enhances tolerance of the transformed yeast cells to salt, osmotic, cold and H2O2-induced oxidative stresses. Moreover, the analysis of TdMnSOD transgenic Arabidopsis plants subjected to different environmental stresses revealed low H2O2 and high proline levels as compared to the wild-type plants. Compared with the non-transformed plants, an increase in the total SOD and two other antioxidant enzyme activities including catalase (CAT) and peroxidases (POD) was observed in the three transgenic lines subjected to abiotic stress. Taken together, these data provide evidence for the involvement of durum wheat TdMnSOD in tolerance to multiple abiotic stresses in crop plants. Copyright © 2016 Elsevier GmbH. All rights reserved.

  5. Arabidopsis ICK/KRP cyclin-dependent kinase inhibitors function to ensure the formation of one megaspore mother cell and one functional megaspore per ovule.

    Directory of Open Access Journals (Sweden)

    Ling Cao

    2018-03-01

    Full Text Available In most plants, the female germline starts with the differentiation of one megaspore mother cell (MMC in each ovule that produces four megaspores through meiosis, one of which survives to become the functional megaspore (FM. The FM further develops into an embryo sac. Little is known regarding the control of MMC formation to one per ovule and the selective survival of the FM. The ICK/KRPs (interactor/inhibitor of cyclin-dependent kinase (CDK/Kip-related proteins are plant CDK inhibitors and cell cycle regulators. Here we report that in the ovules of Arabidopsis mutant with all seven ICK/KRP genes inactivated, supernumerary MMCs, FMs and embryo sacs were formed and the two embryo sacs could be fertilized to form two embryos with separate endosperm compartments. Twin seedlings were observed in about 2% seeds. Further, in the mutant ovules the number and position of surviving megaspores from one MMC were variable, indicating that the positional signal for determining the survival of megaspore was affected. Strikingly, ICK4 fusion protein with yellow fluorescence protein was strongly present in the degenerative megaspores but absent in the FM, suggesting an important role of ICKs in the degeneration of non-functional megaspores. The absence of or much weaker phenotypes in lower orders of mutants and complementation of the septuple mutant by ICK4 or ICK7 indicate that multiple ICK/KRPs function redundantly in restricting the formation of more than one MMC and in the selective survival of FM, which are critical to ensure the development of one embryo sac and one embryo per ovule.

  6. Bipolar Plasma Membrane Distribution of Phosphoinositides and Their Requirement for Auxin-Mediated Cell Polarity and Patterning in Arabidopsis

    NARCIS (Netherlands)

    Tejos, R.; Sauer, M.; Vanneste, S.; Palacios-Gomez, M.; Li, H.; Heilmann, M.; van Wijk, R.; Vermeer, J.E.M.; Heilmann, I.; Munnik, T.; Friml, J.

    2014-01-01

    Cell polarity manifested by asymmetric distribution of cargoes, such as receptors and transporters, within the plasma membrane (PM) is crucial for essential functions in multicellular organisms. In plants, cell polarity (re)establishment is intimately linked to patterning processes. Despite the

  7. Lazarus1, a DUF300 Protein, Contributes to Programmed Cell Death Associated with Arabidopsis acd11 and the Hypersensitive Response

    DEFF Research Database (Denmark)

    Malinovsky, F.G.; Brodersen, P.; Fiil, B.K.

    2010-01-01

    ) mutant exhibits HR-like accelerated cell death, and cell death execution in acd11 shares genetic requirements for HR execution triggered by one subclass of R proteins. Methodology/Principal Findings: To identify genes required for this PCD pathway, we conducted a genetic screen for suppressors of acd11......Background: Programmed cell death (PCD) is a necessary part of the life of multi-cellular organisms. A type of plant PCD is the defensive hypersensitive response (HR) elicited via recognition of a pathogen by host resistance (R) proteins. The lethal, recessive accelerated cell death 11 (acd11......, here called lazarus (laz) mutants. In addition to known suppressors of R protein-mediated HR, we isolated 13 novel complementation groups of dominant and recessive laz mutants. Here we describe laz1, which encodes a protein with a domain of unknown function (DUF300), and demonstrate that LAZ1...

  8. Reduced Wall Acetylation Proteins Play Vital and Distinct Roles in Cell Wall O-Acetylation in Arabidopsis

    DEFF Research Database (Denmark)

    Manabe, Yuzuki; Verhertbruggen, Yves; Gille, Sascha

    2013-01-01

    The Reduced Wall Acetylation (RWA) proteins are involved in cell wall acetylation in plants. Previously, we described a single mutant, rwa2, which has about 20% lower level of O-acetylation in leaf cell walls and no obvious growth or developmental phenotype. In this study, we generated double....... The quadruple rwa mutant can be completely complemented with the RWA2 protein expressed under 35S promoter, indicating the functional redundancy of the RWA proteins. Nevertheless, the degree of acetylation of xylan, (gluco) mannan, and xyloglucan as well as overall cell wall acetylation is affected differently...... in different combinations of triple mutants, suggesting their diversity in substrate preference. The overall degree of wall acetylation in the rwa quadruple mutant was reduced by 63% compared with the wild type, and histochemical analysis of the rwa quadruple mutant stem indicates defects in cell...

  9. EDR2 negatively regulates salicylic acid-based defenses and cell death during powdery mildew infections of Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Nishimura Marc

    2007-07-01

    Full Text Available Abstract Background The hypersensitive necrosis response (HR of resistant plants to avirulent pathogens is a form of programmed cell death in which the plant sacrifices a few cells under attack, restricting pathogen growth into adjacent healthy tissues. In spite of the importance of this defense response, relatively little is known about the plant components that execute the cell death program or about its regulation in response to pathogen attack. Results We isolated the edr2-6 mutant, an allele of the previously described edr2 mutants. We found that edr2-6 exhibited an exaggerated chlorosis and necrosis response to attack by three pathogens, two powdery mildew and one downy mildew species, but not in response to abiotic stresses or attack by the bacterial leaf speck pathogen. The chlorosis and necrosis did not spread beyond inoculated sites suggesting that EDR2 limits the initiation of cell death rather than its spread. The pathogen-induced chlorosis and necrosis of edr2-6 was correlated with a stimulation of the salicylic acid defense pathway and was suppressed in mutants deficient in salicylic acid signaling. EDR2 encodes a novel protein with a pleckstrin homology and a StAR transfer (START domain as well as a plant-specific domain of unknown function, DUF1336. The pleckstrin homology domain binds to phosphatidylinositol-4-phosphate in vitro and an EDR2:HA:GFP protein localizes to endoplasmic reticulum, plasma membrane and endosomes. Conclusion EDR2 acts as a negative regulator of cell death, specifically the cell death elicited by pathogen attack and mediated by the salicylic acid defense pathway. Phosphatidylinositol-4-phosphate may have a role in limiting cell death via its effect on EDR2. This role in cell death may be indirect, by helping to target EDR2 to the appropriate membrane, or it may play a more direct role.

  10. Arabidopsis EXO70A1 recruits Patellin3 to the cell membrane independent of its role as an exocyst subunit

    NARCIS (Netherlands)

    Wu, C.; Tan, L.; van Hooren, M.; Tan, X.; Liu, F.; Li, Y.; Zhao, Y.; Li, B.; Rui, Q.; Munnik, T.; Bao, Y.

    2017-01-01

    The exocyst is a well-known complex which tethers vesicles at the cell membrane before fusion. Whether an individual subunit can execute a unique function is largely unknown. Using yeast-two-hybrid (Y2H) analysis, we found that EXO70A1 interacted with the GOLD domain of Patellin3 (PATL3). The direct

  11. CCR1, an enzyme required for lignin biosynthesis in Arabidopsis, mediates cell proliferation exit for leaf development

    DEFF Research Database (Denmark)

    Xue, Jingshi; Luo, Dexian; Xu, Deyang

    2015-01-01

    A level was dramatically reduced. Cell proliferation in comt ccoaomt leaves was decreased, accompanied by elevated ROS levels, and the mutant phenotypes were partially rescued by treatment with FeA or another antioxidant (N-acetyl-L-cysteine). Taken together, our results suggest that CCR1, FeA and ROS...

  12. Arabidopsis Regenerating Protoplast: A Powerful Model System for Combining the Proteomics of Cell Wall Proteins and the Visualization of Cell Wall Dynamics

    OpenAIRE

    Yokoyama, Ryusuke; Kuki, Hiroaki; Kuroha, Takeshi; Nishitani, Kazuhiko

    2016-01-01

    The development of a range of sub-proteomic approaches to the plant cell wall has identified many of the cell wall proteins. However, it remains difficult to elucidate the precise biological role of each protein and the cell wall dynamics driven by their actions. The plant protoplast provides an excellent means not only for characterizing cell wall proteins, but also for visualizing the dynamics of cell wall regeneration, during which cell wall proteins are secreted. It therefore offers a uni...

  13. Arabidopsis Regenerating Protoplast: A Powerful Model System for Combining the Proteomics of Cell Wall Proteins and the Visualization of Cell Wall Dynamics

    Science.gov (United States)

    Yokoyama, Ryusuke; Kuki, Hiroaki; Kuroha, Takeshi; Nishitani, Kazuhiko

    2016-01-01

    The development of a range of sub-proteomic approaches to the plant cell wall has identified many of the cell wall proteins. However, it remains difficult to elucidate the precise biological role of each protein and the cell wall dynamics driven by their actions. The plant protoplast provides an excellent means not only for characterizing cell wall proteins, but also for visualizing the dynamics of cell wall regeneration, during which cell wall proteins are secreted. It therefore offers a unique opportunity to investigate the de novo construction process of the cell wall. This review deals with sub-proteomic approaches to the plant cell wall through the use of protoplasts, a methodology that will provide the basis for further exploration of cell wall proteins and cell wall dynamics. PMID:28248244

  14. Programmed cell death in the leaves of the Arabidopsis spontaneous necrotic spots (sns-D mutant correlates with increased expression of the eukaryotic translation initiation factor eIF4B2

    Directory of Open Access Journals (Sweden)

    Gwenael M.D.J.-M. Gaussand

    2011-04-01

    Full Text Available From a pool of transgenic Arabidopsis (Arabidopsis thaliana plants harboring an activator T-DNA construct, one mutant was identified that developed spontaneous necrotic spots (sns-D on the rosette leaves under aseptic conditions. The sns-D mutation is dominant and homozygous plants are embryo lethal. The mutant produced smaller rosettes with a different number of stomata than the wild-type. DNA fragmentation in the nuclei of cells in the necrotic spots and a significant increase of caspase-3 and caspase-6 like activities in sns-D leaf extracts indicated that the sns-D mutation caused programmed cell death (PCD. The integration of the activator T-DNA caused an increase of the expression level of At1g13020, which encodes the eukaryotic translation initiation factor eIF4B2. The expression level of eIF4B2 was positively correlated with the severity of sns-D mutant phenotype. Overexpression of the eIF4B2 cDNA mimicked phenotypic traits of the sns-D mutant indicating that the sns-D mutant phenotype is indeed caused by activation tagging of eIF4B2. Thus, incorrect regulation of translation initiation may result in PCD.

  15. Arabidopsis thaliana peroxidase N

    DEFF Research Database (Denmark)

    Mirza, Osman Asghar; Henriksen, A; Ostergaard, L

    2000-01-01

    The structure of the neutral peroxidase from Arabidopsis thaliana (ATP N) has been determined to a resolution of 1.9 A and a free R value of 20.5%. ATP N has the expected characteristic fold of the class III peroxidases, with a C(alpha) r.m.s.d. of 0.82 A when compared with horseradish peroxidase C...

  16. Reference: 241 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available 241 http://metadb.riken.jp/db/SciNetS_ria224i/cria224u4ria224u16024589i Calderon-V...development of Arabidopsis thaliana. 9 2473-85 16024589 2005 Sep The Plant cell Bevan Mike|Calderon-Villalobos Luz I A|Dohmann Esther M N|Kuhnle Carola|Li Hanbing|Schwechheimer Claus

  17. Reference: 295 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available 295 http://metadb.riken.jp/db/SciNetS_ria224i/cria224u4ria224u16284313i Fujita Yas...ng that enhances drought stress tolerance in Arabidopsis. 12 3470-88 16284313 200...5 Dec The Plant cell Fujita Miki|Fujita Yasunari|Hiratsu Keiichiro|Maruyama Kyonoshin|Ohme-Takagi Masaru|Par

  18. Reference: 584 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available ing in Arabidopsis thaliana shoot and root stem cell organizers. 7137 811-4 17429400 2007 Apr Nature Hashimo...nda K et al. 2007 Apr. Nature 446(7137):811-4. Throughout the lifespan of a plant, which in some cases can l... 584 http://metadb.riken.jp/db/SciNetS_ria224i/cria224u4ria224u17429400i Sarkar Ana

  19. Reassessing the role of phospholipase D in the Arabidopsis wounding response

    NARCIS (Netherlands)

    Bargmann, Bastiaan O.R.; Laxalt, Ana M.; Riet, Bas ter; Testerink, Christa; Merquiol, Emmanuelle; Mosblech, Alina; Leon Reyes, H.A.; Pieterse, C.M.J.; Haring, Michel A.; Heilmann, Ingo; Bartels, Dorothea; Munnik, Teun

    2009-01-01

    Plants respond to wounding by means of a multitude of reactions, with the purpose of stifling herbivore assault. Phospholipase D (PLD) has previously been implicated in the wounding response. Arabidopsis (Arabidopsis thaliana) AtPLDa1 has been proposed to be activated in intact cells, and the

  20. Intracellular localization of Arabidopsis sulfurtransferases.

    Science.gov (United States)

    Bauer, Michael; Dietrich, Christof; Nowak, Katharina; Sierralta, Walter D; Papenbrock, Jutta

    2004-06-01

    Sulfurtransferases (Str) comprise a group of enzymes widely distributed in archaea, eubacteria, and eukaryota which catalyze the transfer of a sulfur atom from suitable sulfur donors to nucleophilic sulfur acceptors. In all organisms analyzed to date, small gene families encoding Str proteins have been identified. The gene products were localized to different compartments of the cells. Our interest concerns the localization of Str proteins encoded in the nuclear genome of Arabidopsis. Computer-based prediction methods revealed localization in different compartments of the cell for six putative AtStrs. Several methods were used to determine the localization of the AtStr proteins experimentally. For AtStr1, a mitochondrial localization was demonstrated by immunodetection in the proteome of isolated mitochondria resolved by one- and two-dimensional gel electrophoresis and subsequent blotting. The respective mature AtStr1 protein was identified by mass spectrometry sequencing. The same result was obtained by transient expression of fusion constructs with the green fluorescent protein in Arabidopsis protoplasts, whereas AtStr2 was exclusively localized to the cytoplasm by this method. Three members of the single-domain AtStr were localized in the chloroplasts as demonstrated by transient expression of green fluorescent protein fusions in protoplasts and stomata, whereas the single-domain AtStr18 was shown to be cytoplasmic. The remarkable subcellular distribution of AtStr15 was additionally analyzed by transmission electron immunomicroscopy using a monospecific antibody against green fluorescent protein, indicating an attachment to the thylakoid membrane. The knowledge of the intracellular localization of the members of this multiprotein family will help elucidate their specific functions in the organism.

  1. Regulatory Proteolysis in Arabidopsis-Pathogen Interactions.

    Science.gov (United States)

    Pogány, Miklós; Dankó, Tamás; Kámán-Tóth, Evelin; Schwarczinger, Ildikó; Bozsó, Zoltán

    2015-09-24

    Approximately two and a half percent of protein coding genes in Arabidopsis encode enzymes with known or putative proteolytic activity. Proteases possess not only common housekeeping functions by recycling nonfunctional proteins. By irreversibly cleaving other proteins, they regulate crucial developmental processes and control responses to environmental changes. Regulatory proteolysis is also indispensable in interactions between plants and their microbial pathogens. Proteolytic cleavage is simultaneously used both by plant cells, to recognize and inactivate invading pathogens, and by microbes, to overcome the immune system of the plant and successfully colonize host cells. In this review, we present available results on the group of proteases in the model plant Arabidopsis thaliana whose functions in microbial pathogenesis were confirmed. Pathogen-derived proteolytic factors are also discussed when they are involved in the cleavage of host metabolites. Considering the wealth of review papers available in the field of the ubiquitin-26S proteasome system results on the ubiquitin cascade are not presented. Arabidopsis and its pathogens are conferred with abundant sets of proteases. This review compiles a list of those that are apparently involved in an interaction between the plant and its pathogens, also presenting their molecular partners when available.

  2. Isolation of a novel cell wall architecture mutant of rice with defective Arabidopsis COBL4 ortholog BC1 required for regulated deposition of secondary cell wall components.

    Science.gov (United States)

    Sato, Kanna; Suzuki, Ryu; Nishikubo, Nobuyuki; Takenouchi, Sachi; Ito, Sachiko; Nakano, Yoshimi; Nakaba, Satoshi; Sano, Yuzou; Funada, Ryo; Kajita, Shinya; Kitano, Hidemi; Katayama, Yoshihiro

    2010-06-01

    The plant secondary cell wall is a highly ordered structure composed of various polysaccharides, phenolic components and proteins. Its coordinated regulation of a number of complex metabolic pathways and assembly has not been resolved. To understand the molecular mechanisms that regulate secondary cell wall synthesis, we isolated a novel rice mutant, cell wall architecture1 (cwa1), that exhibits an irregular thickening pattern in the secondary cell wall of sclerenchyma, as well as culm brittleness and reduced cellulose content in mature internodes. Light and transmission electron microscopy revealed that the cwa1 mutant plant has regions of local aggregation in the secondary cell walls of the cortical fibers in its internodes, showing uneven thickness. Ultraviolet microscopic observation indicated that localization of cell wall phenolic components was perturbed and that these components abundantly deposited at the aggregated cell wall regions in sclerenchyma. Therefore, regulation of deposition and assembly of secondary cell wall materials, i.e. phenolic components, appear to be disturbed by mutation of the cwa1 gene. Genetic analysis showed that cwa1 is allelic to brittle culm1 (bc1), which encodes the glycosylphosphatidylinositol-anchored COBRA-like protein specifically in plants. BC1 is known as a regulator that controls the culm mechanical strength and cellulose content in the secondary cell walls of sclerenchyma, but the precise function of BC1 has not been resolved. Our results suggest that CWA1/BC1 has an essential role in assembling cell wall constituents at their appropriate sites, thereby enabling synthesis of solid and flexible internodes in rice.

  3. S-nitrosoglutathione promotes cell wall remodelling, alters the transcriptional profile and induces root hair formation in the hairless root hair defective 6 (rhd6) mutant of Arabidopsis thaliana.

    Science.gov (United States)

    Moro, Camila Fernandes; Gaspar, Marilia; da Silva, Felipe Rodrigues; Pattathil, Sivakumar; Hahn, Michael G; Salgado, Ione; Braga, Marcia Regina

    2017-03-01

    Nitric oxide (NO) exerts pleiotropic effects on plant development; however, its involvement in cell wall modification during root hair formation (RHF) has not yet been addressed. Here, mutants of Arabidopsis thaliana with altered root hair phenotypes were used to assess the involvement of S-nitrosoglutathione (GSNO), the primary NO source, in cell wall dynamics and gene expression in roots induced to form hairs. GSNO and auxin restored the root hair phenotype of the hairless root hair defective 6 (rhd6) mutant. A positive correlation was observed between increased NO production and RHF induced by auxin in rhd6 and transparent testa glabra (ttg) mutants. Deposition of an epitope within rhamnogalacturonan-I recognized by the CCRC-M2 antibody was delayed in root hair cells (trichoblasts) compared with nonhair cells (atrichoblasts). GSNO, but not auxin, restored the wild-type root glycome and transcriptome profiles in rhd6, modulating the expression of a large number of genes related to cell wall composition and metabolism, as well as those encoding ribosomal proteins, DNA and histone-modifying enzymes and proteins involved in post-translational modification. Our results demonstrate that NO plays a key role in cell wall remodelling in trichoblasts and suggest that it also participates in chromatin modification in root cells of A. thaliana. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

  4. Arabidopsis SHR and SCR transcription factors and AUX1 auxin influx carrier control the switch between adventitious rooting and xylogenesis in planta and in in vitro cultured thin cell layers.

    Science.gov (United States)

    Della Rovere, F; Fattorini, L; D'Angeli, S; Veloccia, A; Del Duca, S; Cai, G; Falasca, G; Altamura, M M

    2015-03-01

    Adventitious roots (ARs) are essential for vegetative propagation. The Arabidopsis thaliana transcription factors SHORT ROOT (SHR) and SCARECROW (SCR) affect primary/lateral root development, but their involvement in AR formation is uncertain. LAX3 and AUX1 auxin influx carriers contribute to primary/lateral root development. LAX3 expression is regulated by SHR, and LAX3 contributes to AR tip auxin maximum. In contrast, AUX1 involvement in AR development is unknown. Xylogenesis is induced by auxin plus cytokinin as is AR formation, but the genes involved are largely unknown. Stem thin cell layers (TCLs) form ARs and undergo xylogenesis under the same auxin plus cytokinin input. The aim of this research was to investigate SHR, SCR, AUX1 and LAX3 involvement in AR formation and xylogenesis in intact hypocotyls and stem TCLs in arabidopsis. Hypocotyls of scr-1, shr-1, lax3, aux1-21 and lax3/aux1-21 Arabidopsis thaliana null mutant seedlings grown with or without auxin plus cytokinin were examined histologically, as were stem TCLs cultured with auxin plus cytokinin. SCR and AUX1 expression was monitored using pSCR::GFP and AUX1::GUS lines, and LAX3 expression and auxin localization during xylogenesis were monitored by using LAX3::GUS and DR5::GUS lines. AR formation was inhibited in all mutants, except lax3. SCR was expressed in pericycle anticlinally derived AR-forming cells of intact hypocotyls, and in cell clumps forming AR meristemoids of TCLs. The apex was anomalous in shr and scr ARs. In all mutant hypocotyls, the pericycle divided periclinally to produce xylogenesis. Xylary element maturation was favoured by auxin plus cytokinin in shr and aux1-21. Xylogenesis was enhanced in TCLs, and in aux1-21 and shr in particular. AUX1 was expressed before LAX3, i.e. in the early derivatives leading to either ARs or xylogenesis. AR formation and xylogenesis are developmental programmes that are inversely related, but they involve fine-tuning by the same proteins, namely SHR

  5. Analysis of plastid number, size, and distribution in Arabidopsis plants by light and fluorescence microscopy.

    Science.gov (United States)

    Pyke, Kevin

    2011-01-01

    Methods are described which allow one to observe chloroplasts in mesophyll cells from leaves of Arabidopsis, determine their number per cell, measure their area, and determine a value for chloroplast coverage inside mesophyll cells. Non-green plastids can also be imaged either by using staining, or by exploiting fluorescent proteins targeted to the plastid in non-green parts of the plant, such as the roots, in transgenic Arabidopsis.

  6. Proteomic identification of S-nitrosylated proteins in Arabidopsis

    DEFF Research Database (Denmark)

    Lindermayr, C.; Saalbach, G.; Durner, J.

    2005-01-01

    Although nitric oxide (NO) has grown into a key signaling molecule in plants during the last few years, less is known about how NO regulates different events in plants. Analyses of NO-dependent processes in animal systems have demonstrated protein S-nitrosylation of cysteine (Cys) residues...... to be one of the dominant regulation mechanisms for many animal proteins. For plants, the principle of S-nitrosylation remained to be elucidated. We generated S-nitrosothiols by treating extracts from Arabidopsis (Arabidopsis thaliana) cell suspension cultures with the NO-donor S......-nitrosoglutathione. Furthermore, Arabidopsis plants were treated with gaseous NO to analyze whether S-nitrosylation can occur in the specific redox environment of a plant cell in vivo. S-Nitrosylated proteins were detected by a biotin switch method, converting S-nitrosylated Cys to biotinylated Cys. Biotin-labeled proteins were...

  7. Knockout of Arabidopsis accelerated-cell-death11 encoding a sphingosine transfer protein causes activation of programmed cell death and defense

    DEFF Research Database (Denmark)

    Brodersen, Peter; Petersen, Morten; Pike, Helen M

    2002-01-01

    by avirulent pathogens. Global transcriptional changes during programmed cell death (PCD) and defense activation in acd11 were monitored by cDNA microarray hybridization. The PCD and defense pathways activated in acd11 are salicylic acid (SA) dependent, but do not require intact jasmonic acid or ethylene...

  8. The vacuolar transport of aleurain-GFP and 2S albumin-GFP fusions is mediated by the same pre-vacuolar compartments in tobacco BY-2 and Arabidopsis suspension cultured cells.

    Science.gov (United States)

    Miao, Yansong; Li, Kwun Yee; Li, Hong-Ye; Yao, Xiaoqiang; Jiang, Liwen

    2008-12-01

    Soluble proteins reach vacuoles because they contain vacuolar sorting determinants (VSDs) that are recognized by vacuolar sorting receptor (VSR) proteins. Pre-vacuolar compartments (PVCs), defined by VSRs and GFP-VSR reporters in tobacco BY-2 cells, are membrane-bound intermediate organelles that mediate protein traffic from the Golgi apparatus to the vacuole in plant cells. Multiple pathways have been demonstrated to be responsible for vacuolar transport of lytic enzymes and storage proteins to the lytic vacuole (LV) and the protein storage vacuole (PSV), respectively. However, the nature of PVCs for LV and PSV pathways remains unclear. Here, we used two fluorescent reporters, aleurain-GFP and 2S albumin-GFP, that represent traffic of lytic enzymes and storage proteins to LV and PSV, respectively, to study the PVC-mediated transport pathways via transient expression in suspension cultured cells. We demonstrated that the vacuolar transport of aleurain-GFP and 2S albumin-GFP was mediated by the same PVC populations in both tobacco BY-2 and Arabidopsis suspension cultured cells. These PVCs were defined by the seven GFP-AtVSR reporters. In wortmannin-treated cells, the vacuolated PVCs contained the mRFP-AtVSR reporter in their limiting membranes, whereas the soluble aleurain-GFP or 2S albumin-GFP remained in the lumen of the PVCs, indicating a possible in vivo relationship between receptor and cargo within PVCs.

  9. An Arabidopsis callose synthase

    DEFF Research Database (Denmark)

    Ostergaard, Lars; Petersen, Morten; Mattsson, Ole

    2002-01-01

    in the Arabidopsis mpk4 mutant which exhibits systemic acquired resistance (SAR), elevated beta-1,3-glucan synthase activity, and increased callose levels. In addition, AtGsl5 is a likely target of salicylic acid (SA)-dependent SAR, since AtGsl5 mRNA accumulation is induced by SA in wild-type plants, while...... expression of the nahG salicylate hydroxylase reduces AtGsl5 mRNA levels in the mpk4 mutant. These results indicate that AtGsl5 is likely involved in callose synthesis in flowering tissues and in the mpk4 mutant....

  10. Stochastic gene expression in Arabidopsis thaliana.

    Science.gov (United States)

    Araújo, Ilka Schultheiß; Pietsch, Jessica Magdalena; Keizer, Emma Mathilde; Greese, Bettina; Balkunde, Rachappa; Fleck, Christian; Hülskamp, Martin

    2017-12-14

    Although plant development is highly reproducible, some stochasticity exists. This developmental stochasticity may be caused by noisy gene expression. Here we analyze the fluctuation of protein expression in Arabidopsis thaliana. Using the photoconvertible KikGR marker, we show that the protein expressions of individual cells fluctuate over time. A dual reporter system was used to study extrinsic and intrinsic noise of marker gene expression. We report that extrinsic noise is higher than intrinsic noise and that extrinsic noise in stomata is clearly lower in comparison to several other tissues/cell types. Finally, we show that cells are coupled with respect to stochastic protein expression in young leaves, hypocotyls and roots but not in mature leaves. Our data indicate that stochasticity of gene expression can vary between tissues/cell types and that it can be coupled in a non-cell-autonomous manner.

  11. Identification of proteins interacting with Arabidopsis ACD11

    DEFF Research Database (Denmark)

    Petersen, Nikolaj H T; Joensen, Jan; McKinney, Lea V

    2009-01-01

    The Arabidopsis ACD11 gene encodes a sphingosine transfer protein and was identified by the accelerated cell death phenotype of the loss of function acd11 mutant, which exhibits heightened expression of genes involved in the disease resistance hypersensitive response (HR). We used ACD11 as bait...... in a yeast two-hybrid screen of an Arabidopsis cDNA library to identify ACD11 interacting proteins. One interactor identified is a protein of unknown function with an RNA recognition motif (RRM) designated BPA1 (binding partner of ACD11). Co-immunoprecipitation experiments confirmed the ACD11-BPA1...

  12. Photorepair mutants of Arabidopsis

    International Nuclear Information System (INIS)

    Jiang, C.Z.; Yee, J.; Mitchell, D.L.; Britt, A.B.

    1997-01-01

    UV radiation induces two major DNA damage products, the cyclobutane pyrimidine dimer (CPD) and, at a lower frequency, the pyrimidine (6-4) pyrimidinone dimer (6-4 product). Although Escherichia coli and Saccharomyces cerevisiae produce a CPD-specific photolyase that eliminates only this class of dimer, Arabidopsis thaliana, Drosophila melanogaster, Crotalus atrox, and Xenopus laevis have recently been shown to photoreactivate both CPDs and 6-4 products. We describe the isolation and characterization of two new classes of mutants of Arabidopsis, termed uvr2 and uvr3, that are defective in the photoreactivation of CPDs and 6-4 products, respectively. We demonstrate that the CPD photolyase mutation is genetically linked to a DNA sequence encoding a type II (metazoan) CPD photolyase. In addition, we are able to generate plants in which only CPDs or 6-4 products are photoreactivated in the nuclear genome by exposing these mutants to UV light and then allowing them to repair one or the other class of dimers. This provides us with a unique opportunity to study the biological consequences of each of these two major UV-induced photoproducts in an intact living system

  13. Arabidopsis peroxisome proteomics

    Directory of Open Access Journals (Sweden)

    John D. Bussell

    2013-04-01

    Full Text Available The analytical depth of investigation of the peroxisomal proteome of the model plant Arabidopsis thaliana has not yet reached that of other major cellular organelles such as chloroplasts or mitochondria. This is primarily due to the difficulties associated with isolating and obtaining purified samples of peroxisomes from Arabidopsis. So far only a handful of research groups have been successful in obtaining such fractions. To make things worse, enriched peroxisome fractions frequently suffer from significant organellar contamination, lowering confidence in localization assignment of the identified proteins. As with other cellular compartments, identification of peroxisomal proteins forms the basis for investigations of the dynamics of the peroxisomal proteome. It is therefore not surprising that, in terms of functional analyses by proteomic means, there remains a considerable gap between peroxisomes and chloroplasts or mitochondria. Alternative strategies are needed to overcome the obstacle of hard-to-obtain organellar fractions. This will help to close the knowledge gap between peroxisomes and other organelles and provide a full picture of the physiological pathways shared between organelles. In this review we briefly summarize the status quo and discuss some of the methodological alternatives to classic organelle proteomic approaches.

  14. Differential effects of carbohydrates on arabidopsis pollen germination

    Czech Academy of Sciences Publication Activity Database

    Hirsche, J.; Fernández, J. M. G.; Stabentheiner, E.; Großkinsky, D.K.; Roitsch, Thomas

    2017-01-01

    Roč. 58, č. 4 (2017), s. 691-701 ISSN 0032-0781 R&D Projects: GA MŠk(CZ) LO1415 Institutional support: RVO:67179843 Keywords : Arabidopsis thaliana * Carbohydrates * Metabolic regulation * Pollen germination * Signaling * Structure-function relationship Subject RIV: EF - Botanics OBOR OECD: Cell biology Impact factor: 4.760, year: 2016

  15. The Arabidopsis cytosolic proteome

    DEFF Research Database (Denmark)

    Ito, Jun; Parsons, Harriet Tempé; Heazlewood, Joshua L.

    2014-01-01

    compartments. However, a detailed study of enriched cytosolic fractions from Arabidopsis cell culture has been performed only recently, with over 1,000 proteins reproducibly identified by mass spectrometry. The number of proteins allocated to the cytosol nearly doubles to 1,802 if a series of targeted...

  16. The influences of Hygromycin B on growth of Arabidopsis thaliana ...

    African Journals Online (AJOL)

    In this article, growth and development of Arabidopsis thaliana seedling cotyledon and leaf were evidently affected by Hygromycin B. As compared to the control, cotyledon of seedling on Murashige and Skoog (MS) with Hygromycin B was very small and its leaf was not formed. Along with increase in culture time, cells in the ...

  17. Reference: 453 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available ctor. We demonstrate that this protein functions as a transcriptional repressor in vivo. The express...ion of all members of the CYCLINA2 (CYCA2) family was reduced in an ILP1 overexpressing l...ine, and the mouse (Mus musculus) homolog of ILP1 repressed cyclin A2 expression in mouse NIH3T3 cells. T-DN...A insertion mutants of ILP1 showed reduced polyploidy and upregulated all CYCA2 express...ion. Furthermore, loss of CYCA2;1 expression induces an increase in polyploidy in Arabidopsis. We demo

  18. Reference: 387 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available Michael F et al. 2006 Jul. Plant Physiol. 141(3):957-65. Karyogamy, or nuclear fusion, is essential for sex...ual reproduction. In angiosperms, karyogamy occurs three times: twice during double fertilization of the egg...e two polar nuclei fuse to form the diploid central cell nucleus. The molecular mechanisms controlling karyoga...etected during megagametogenesis. nfd1 is also affected in karyogamy during double fertilization. Using tran...odes the Arabidopsis RPL21M protein and is required for karyogamy during female g

  19. Reference: 657 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available wth retardation. Double knockout atphb3 atphb4 plants were not viable, but transgenic lines overexpressing AtPHB3 or AtPHB...livier et al. 2007 Dec. Plant J. 52(5):850-64. The Arabidopsis thaliana genome expresses five evolutionarily... conserved prohibitin (PHB) genes that are divided into type-I (AtPHB3 and AtPHB4) and type-II (AtPHB1, AtPHB2 and AtPHB...6) classes, based on their phylogenetic relationships with yeast PHB1 and PHB...2, respectively. Yeast and animal PHBs are reported to have diverse roles in the cell cycle, mitocho

  20. Arabidopsis SNAREs SYP61 and SYP121 coordinate the trafficking of plasma membrane aquaporin PIP2;7 to modulate the cell membrane water permeability.

    Science.gov (United States)

    Hachez, Charles; Laloux, Timothée; Reinhardt, Hagen; Cavez, Damien; Degand, Hervé; Grefen, Christopher; De Rycke, Riet; Inzé, Dirk; Blatt, Michael R; Russinova, Eugenia; Chaumont, François

    2014-07-01

    Plant plasma membrane intrinsic proteins (PIPs) are aquaporins that facilitate the passive movement of water and small neutral solutes through biological membranes. Here, we report that post-Golgi trafficking of PIP2;7 in Arabidopsis thaliana involves specific interactions with two syntaxin proteins, namely, the Qc-SNARE SYP61 and the Qa-SNARE SYP121, that the proper delivery of PIP2;7 to the plasma membrane depends on the activity of the two SNAREs, and that the SNAREs colocalize and physically interact. These findings are indicative of an important role for SYP61 and SYP121, possibly forming a SNARE complex. Our data support a model in which direct interactions between specific SNARE proteins and PIP aquaporins modulate their post-Golgi trafficking and thus contribute to the fine-tuning of the water permeability of the plasma membrane. © 2014 American Society of Plant Biologists. All rights reserved.

  1. Transgenic Arabidopsis Gene Expression System

    Science.gov (United States)

    Ferl, Robert; Paul, Anna-Lisa

    2009-01-01

    The Transgenic Arabidopsis Gene Expression System (TAGES) investigation is one in a pair of investigations that use the Advanced Biological Research System (ABRS) facility. TAGES uses Arabidopsis thaliana, thale cress, with sensor promoter-reporter gene constructs that render the plants as biomonitors (an organism used to determine the quality of the surrounding environment) of their environment using real-time nondestructive Green Fluorescent Protein (GFP) imagery and traditional postflight analyses.

  2. The genome of Arabidopsis thaliana.

    OpenAIRE

    Goodman, H M; Ecker, J R; Dean, C

    1995-01-01

    Arabidopsis thaliana is a small flowering plant that is a member of the family cruciferae. It has many characteristics--diploid genetics, rapid growth cycle, relatively low repetitive DNA content, and small genome size--that recommend it as the model for a plant genome project. The current status of the genetic and physical maps, as well as efforts to sequence the genome, are presented. Examples are given of genes isolated by using map-based cloning. The importance of the Arabidopsis project ...

  3. Reference: 783 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available xpression of the Arabidopsis 10-kilodalton acyl-coenzyme A-binding protein ACBP6 en...phospholipid metabolism in Arabidopsis, including the possibility of ACBP6 in the cytosolic trafficking of phosphatidylcholine. Overe

  4. Reference: 774 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available an essential gene, the disruption of which causes embryonic lethality. Plants carrying a hypomorphic smg7 mu...e progression from anaphase to telophase in the second meiotic division in Arabidopsis. Arabidopsis SMG7 is

  5. Arabidopsis thaliana glucuronosyltransferase in family GT14

    DEFF Research Database (Denmark)

    Dilokpimol, Adiphol; Geshi, Naomi

    2014-01-01

    Arabinogalactan proteins are abundant cell-surface proteoglycans in plants and are involved in many cellular processes including somatic embryogenesis, cell-cell interactions, and cell elongation. We reported a glucuronosyltransferase encoded by Arabidopsis AtGlcAT14A, which catalyzes an addition...

  6. Multidimensional fluorescence microscopy of multiple organelles in Arabidopsis seedlings

    Directory of Open Access Journals (Sweden)

    Morales Andrea

    2008-05-01

    Full Text Available Abstract Background The isolation of green fluorescent protein (GFP and the development of spectral variants over the past decade have begun to reveal the dynamic nature of protein trafficking and organelle motility. In planta analyses of this dynamic process have typically been limited to only two organelles or proteins at a time in only a few cell types. Results We generated a transgenic Arabidopsis plant that contains four spectrally different fluorescent proteins. Nuclei, plastids, mitochondria and plasma membranes were genetically tagged with cyan, red, yellow and green fluorescent proteins, respectively. In addition, methods to track nuclei, mitochondria and chloroplasts and quantify the interaction between these organelles at a submicron resolution were developed. These analyzes revealed that N-ethylmaleimide disrupts nuclear-mitochondrial but not nuclear-plastids interactions in root epidermal cells of live Arabidopsis seedlings. Conclusion We developed a tool and associated methods for analyzing the complex dynamic of organelle-organelle interactions in real time in planta. Homozygous transgenic Arabidopsis (Kaleidocell is available through Arabidopsis Biological Resource Center.

  7. Diuretics Prime Plant Immunity in Arabidopsis thaliana

    Science.gov (United States)

    Noutoshi, Yoshiteru; Ikeda, Mika; Shirasu, Ken

    2012-01-01

    Plant activators are agrochemicals that activate the plant immune system, thereby enhancing disease resistance. Due to their prophylactic and durable effects on a wide spectrum of diseases, plant activators can provide synergistic crop protection when used in combination with traditional pest controls. Although plant activators have achieved great success in wet-rice farming practices in Asia, their use is still limited. To isolate novel plant activators applicable to other crops, we screened a chemical library using a method that can selectively identify immune-priming compounds. Here, we report the isolation and characterization of three diuretics, bumetanide, bendroflumethiazide and clopamide, as immune-priming compounds. These drugs upregulate the immunity-related cell death of Arabidopsis suspension-cultured cells induced with an avirulent strain of Pseudomonas syringae pv. tomato in a concentration-dependent manner. The application of these compounds to Arabidopsis plants confers disease resistance to not only the avirulent but also a virulent strain of the pathogen. Unlike salicylic acid, an endogenous phytohormone that governs disease resistance in response to biotrophic pathogens, the three diuretic compounds analyzed here do not induce PR1 or inhibit plant growth, showing potential as lead compounds in a practical application. PMID:23144763

  8. Plant-specific histone deacetylases HDT1/2 regulate GIBBERELLIN 2-OXIDASE2 expression to control arabidopsis root meristem cell number

    NARCIS (Netherlands)

    Li, Huchen; Torres-Garcia, Jesus; Latrasse, David; Benhamed, Moussa; Schilderink, Stefan; Zhou, Wenkun; Kulikova, Olga; Hirt, Heribert; Bisseling, Ton

    2017-01-01

    Root growth is modulated by environmental factors and depends on cell production in the root meristem (RM). New cells in the meristem are generated by stem cells and transit-amplifying cells, which together determine RM cell number. Transcription factors and chromatin-remodeling factors have been

  9. Females and males of root-parasitic cyst nematodes induce different symplasmic connections between their syncytial feeding cells and the phloem in Arabidopsis thaliana.

    Science.gov (United States)

    Hofmann, Julia; Grundler, Florian M W

    2006-01-01

    Root syncytia induced by the beet cyst nematode Heterodera schachtii were thought to be symplasmically isolated. A recent study with mobile and immobile GFP constructs expressed in transgenic Arabidopsis plants under the control of pAtSUC2 showed that only mobile GFP could be detected in syncytia and suggested the existence of plasmodesmata between syncytia and the phloem. In the present study the existence of plasmodesmata between syncytia and the phloem is proven by grafting experiments. This technique rules out the possibility that GFP accumulation in syncytia is due to GFP expression in syncytia. Mobile GFP could be followed from transgenic scions carrying a pAtSUC2-gfp fusion construct via wild-type rootstocks into nematode-induced syncytia. While GFP could be detected in all syncytia associated to female nematodes, it was never observed in syncytia of male juveniles. As no GFP-mRNA could be detected in the rootstock we postulate that GFP as protein entered syncytia of females via plasmodesmata, while the protein was excluded from syncytia of male juveniles by plasmodesmata with a lower size exclusion limit.

  10. FRIENDLY regulates mitochondrial distribution, fusion, and quality control in Arabidopsis.

    Science.gov (United States)

    El Zawily, Amr M; Schwarzländer, Markus; Finkemeier, Iris; Johnston, Iain G; Benamar, Abdelilah; Cao, Yongguo; Gissot, Clémence; Meyer, Andreas J; Wilson, Ken; Datla, Raju; Macherel, David; Jones, Nick S; Logan, David C

    2014-10-01

    Mitochondria are defining components of most eukaryotes. However, higher plant mitochondria differ biochemically, morphologically, and dynamically from those in other eukaryotes. FRIENDLY, a member of the CLUSTERED MITOCHONDRIA superfamily, is conserved among eukaryotes and is required for correct distribution of mitochondria within the cell. We sought to understand how disruption of FRIENDLY function in Arabidopsis (Arabidopsis thaliana) leads to mitochondrial clustering and the effects of this aberrant chondriome on cell and whole-plant physiology. We present evidence for a role of FRIENDLY in mediating intermitochondrial association, which is a necessary prelude to mitochondrial fusion. We demonstrate that disruption of mitochondrial association, motility, and chondriome structure in friendly affects mitochondrial quality control and leads to mitochondrial stress, cell death, and strong growth phenotypes. © 2014 American Society of Plant Biologists. All Rights Reserved.

  11. Arabidopsis thaliana peroxidase N

    DEFF Research Database (Denmark)

    Mirza, Osman Asghar; Henriksen, A; Ostergaard, L

    2000-01-01

    The structure of the neutral peroxidase from Arabidopsis thaliana (ATP N) has been determined to a resolution of 1.9 A and a free R value of 20.5%. ATP N has the expected characteristic fold of the class III peroxidases, with a C(alpha) r.m.s.d. of 0.82 A when compared with horseradish peroxidase C...... (HRP C). HRP C is 54% identical to ATP N in sequence. When the structures of four class III plant peroxidases are superimposed, the regions with structural differences are non-randomly distributed; all are located in one half of the molecule. The architecture of the haem pocket of ATP N is very similar...... to that of HRP C, in agreement with the low small-molecule substrate specificity of all class III peroxidases. The structure of ATP N suggests that the pH dependence of the substrate turnover will differ from that of HRP C owing to differences in polarity of the residues in the substrate-access channel. Since...

  12. Local evolution of seed flotation in Arabidopsis.

    Directory of Open Access Journals (Sweden)

    Susana Saez-Aguayo

    2014-03-01

    Full Text Available Arabidopsis seeds rapidly release hydrophilic polysaccharides from the seed coat on imbibition. These form a heavy mucilage layer around the seed that makes it sink in water. Fourteen natural Arabidopsis variants from central Asia and Scandinavia were identified with seeds that have modified mucilage release and float. Four of these have a novel mucilage phenotype with almost none of the released mucilage adhering to the seed and the absence of cellulose microfibrils. Mucilage release was modified in the variants by ten independent causal mutations in four different loci. Seven distinct mutations affected one locus, coding the MUM2 β-D-galactosidase, and represent a striking example of allelic heterogeneity. The modification of mucilage release has thus evolved a number of times independently in two restricted geographical zones. All the natural mutants identified still accumulated mucilage polysaccharides in seed coat epidermal cells. Using nuclear magnetic resonance (NMR relaxometry their production and retention was shown to reduce water mobility into internal seed tissues during imbibition, which would help to maintain seed buoyancy. Surprisingly, despite released mucilage being an excellent hydrogel it did not increase the rate of water uptake by internal seed tissues and is more likely to play a role in retaining water around the seed.

  13. Transcription profiling by array of the response of Arabidopsis cultivar Columbia etiolated seedlings and undifferentiated tissue culture cells to the spaceflight environment

    Data.gov (United States)

    National Aeronautics and Space Administration — We address a key baseline question of whether gene expression changes are induced by the orbital environment and then we ask whether undifferentiated cells cells...

  14. CRISPR/Cas9-mediated gene targeting in Arabidopsis using sequential transformation.

    Science.gov (United States)

    Miki, Daisuke; Zhang, Wenxin; Zeng, Wenjie; Feng, Zhengyan; Zhu, Jian-Kang

    2018-05-17

    Homologous recombination-based gene targeting is a powerful tool for precise genome modification and has been widely used in organisms ranging from yeast to higher organisms such as Drosophila and mouse. However, gene targeting in higher plants, including the most widely used model plant Arabidopsis thaliana, remains challenging. Here we report a sequential transformation method for gene targeting in Arabidopsis. We find that parental lines expressing the bacterial endonuclease Cas9 from the egg cell- and early embryo-specific DD45 gene promoter can improve the frequency of single-guide RNA-targeted gene knock-ins and sequence replacements via homologous recombination at several endogenous sites in the Arabidopsis genome. These heritable gene targeting can be identified by regular PCR. Our approach enables routine and fine manipulation of the Arabidopsis genome.

  15. Identification of redox-sensitive cysteines in the arabidopsis proteome using OxiTRAQ, a quantitative redox proteomics method

    KAUST Repository

    Liu, Pei; Zhang, Huoming; Wang, Hai; Xia, Yiji

    2014-01-01

    -throughput quantitative proteomic approach termed OxiTRAQ for identifying proteins whose thiols undergo reversible oxidative modifications in Arabidopsis cells subjected to oxidative stress. In this approach, a biotinylated thiol-reactive reagent is used for differential

  16. Exploiting natural variation in Arabidopsis

    NARCIS (Netherlands)

    Molenaar, J.A.; Keurentjes, J.J.B.; Sanchez-Serrano, J.J.; Salinas, J.

    2014-01-01

    Natural variation for many traits is present within the species Arabidopsis thaliana. This chapter describes the use of natural variation to elucidate genes underlying the regulation of quantitative traits. It deals with the development and use of mapping populations, the detection and handling of

  17. Collection of apoplastic fluids from Arabidopsis thaliana leaves

    DEFF Research Database (Denmark)

    Madsen, Svend Roesen; Nour-Eldin, Hussam Hassan; Halkier, Barbara Ann

    2016-01-01

    The leaf apoplast comprises the extracellular continuum outside cell membranes. A broad range of processes take place in the apoplast, including intercellular signaling, metabolite transport, and plant-microbe interactions. To study these processes, it is essential to analyze the metabolite conte...... in apoplastic fluids. Due to the fragile nature of leaf tissues, it is a challenge to obtain apoplastic fluids from leaves. Here, methods to collect apoplastic washing fluid and guttation fluid from Arabidopsis thaliana leaves are described....

  18. Study of genes induced by ionizing radiations at Arabidopsis thaliana: identification and molecular characterization of the ATGR1 gene, a new gene encoding a protein involved in plant cell division

    International Nuclear Information System (INIS)

    Deveaux, Yves

    1999-01-01

    DNA damage, that can be experimentally introduced by ionizing radiation (IR), induces complex signal transduction pathways leading to cell recovery or, alternatively to programmed cell death if damages are too severe. To identify the inducible components of the response to genotoxic stress in plants, we have screened by Differential Display for mRNAs that rapidly and strongly accumulate after IR treatment in A. thaliana cells. We have characterized ATGR1, a new single copy Arabidopsis gene encoding a PEST-box protein of unknown function. In unstressed plant organs the ATGR1 mRNA is hardly detectable, whereas the protein is present in extracts prepared from roots, shoot meristems and inflorescences, that all contain large amounts of actively dividing cells. This pattern is confirmed by immuno localisation on tissue sections that shows constitutive ATGR1 protein expression covering the root elongation zone, the shoot meristem, leaf primordial and the ovules of developing flowers. Histochemical analysis of transgenic plants expressing the GUS reporter gene under the control of the ATGR1 promoter, demonstrate that the developmental and tissue-specific profile of ATGR1 protein expression is conferred by the gene promoter. The massive, transient and dose-dependent accumulation of ATGR1 transcripts after IR treatment observed in all plant organs does not lead to significant changes in ATGR1 protein pattern. Stable ATGR1 protein overexpression, as exemplified by transgenic A. thaliana plants that contain a 35S promoter-ATGR1 gene fusion, does not induce notable changes of the overall ATGR1 protein level, but leads to male and female sterility. The cause of sterility is a lack of correct chromosome assembly and distribution at the stage metaphase II of meiosis. Taken together our results show that i) ATGR1 gene expression is associated to cell division during plant development ii) the ATGR1 protein level is regulated at the transcriptional and post-transcriptional level iii

  19. Pyridine nucleotide cycling and control of intracellular redox state in relation to poly (ADP-ribose) polymerase activity and nuclear localization of glutathione during exponential growth of Arabidopsis cells in culture.

    Science.gov (United States)

    Pellny, Till K; Locato, Vittoria; Vivancos, Pedro Diaz; Markovic, Jelena; De Gara, Laura; Pallardó, Federico V; Foyer, Christine H

    2009-05-01

    Pyridine nucleotides, ascorbate and glutathione are major redox metabolites in plant cells, with specific roles in cellular redox homeostasis and the regulation of the cell cycle. However, the regulation of these metabolite pools during exponential growth and their precise functions in the cell cycle remain to be characterized. The present analysis of the abundance of ascorbate, glutathione, and pyridine nucleotides during exponential growth of Arabidopsis cells in culture provides evidence for the differential regulation of each of these redox pools. Ascorbate was most abundant early in the growth cycle, but glutathione was low at this point. The cellular ascorbate to dehydroascorbate and reduced glutathione (GSH) to glutathione disulphide ratios were high and constant but the pyridine nucleotide pools were largely oxidized over the period of exponential growth and only became more reduced once growth had ceased. The glutathione pool increased in parallel with poly (ADP-ribose) polymerase (PARP) activities and with increases in the abundance of PARP1 and PARP2 mRNAs at a time of high cell cycle activity as indicated by transcriptome information. Marked changes in the intracellular partitioning of GSH between the cytoplasm and nucleus were observed. Extension of the exponential growth phase by dilution or changing the media led to increases in the glutathione and nicotinamide adenine dinucleotide, oxidized form (NAD)-plus-nicotinamide adenine dinucleotide, reduced form (NADH) pools and to higher NAD/NADH ratios but the nicotinamide adenine dinucleotide phosphate, oxidized form (NADP)-plus-nicotinamide adenine dinucleotide phosphate, reduced form (NADPH) pool sizes, and NAPD/NADPH ratios were much less affected. The ascorbate, glutathione, and pyridine nucleotide pools and PARP activity decreased before the exponential growth phase ended. We conclude that there are marked changes in intracellular redox state during the growth cycle but that redox homeostasis is

  20. Two Nucleolar Proteins, GDP1 and OLI2, Function As Ribosome Biogenesis Factors and Are Preferentially Involved in Promotion of Leaf Cell Proliferation without Strongly Affecting Leaf Adaxial–Abaxial Patterning in Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Koji Kojima

    2018-01-01

    Full Text Available Leaf abaxial–adaxial patterning is dependent on the mutual repression of leaf polarity genes expressed either adaxially or abaxially. In Arabidopsis thaliana, this process is strongly affected by mutations in ribosomal protein genes and in ribosome biogenesis genes in a sensitized genetic background, such as asymmetric leaves2 (as2. Most ribosome-related mutants by themselves do not show leaf abaxialization, and one of their typical phenotypes is the formation of pointed rather than rounded leaves. In this study, we characterized two ribosome-related mutants to understand how ribosome biogenesis is linked to several aspects of leaf development. Previously, we isolated oligocellula2 (oli2 which exhibits the pointed-leaf phenotype and has a cell proliferation defect. OLI2 encodes a homolog of Nop2 in Saccharomyces cerevisiae, a ribosome biogenesis factor involved in pre-60S subunit maturation. In this study, we found another pointed-leaf mutant that carries a mutation in a gene encoding an uncharacterized protein with a G-patch domain. Similar to oli2, this mutant, named g-patch domain protein1 (gdp1, has a reduced number of leaf cells. In addition, gdp1 oli2 double mutants showed a strong genetic interaction such that they synergistically impaired cell proliferation in leaves and produced markedly larger cells. On the other hand, they showed additive phenotypes when combined with several known ribosomal protein mutants. Furthermore, these mutants have a defect in pre-rRNA processing. GDP1 and OLI2 are strongly expressed in tissues with high cell proliferation activity, and GDP1-GFP and GFP-OLI2 are localized in the nucleolus. These results suggest that OLI2 and GDP1 are involved in ribosome biogenesis. We then examined the effects of gdp1 and oli2 on adaxial–abaxial patterning by crossing them with as2. Interestingly, neither gdp1 nor oli2 strongly enhanced the leaf polarity defect of as2. Similar results were obtained with as2 gdp1 oli2

  1. Proteomics investigation of endogenous S-nitrosylation in Arabidopsis

    International Nuclear Information System (INIS)

    Fares, Abasse; Rossignol, Michel; Peltier, Jean-Benoît

    2011-01-01

    Highlights: ► Identification and quantification of nitrosothiols. ► A first dataset of endogenously nitrosylated cysteines in Arabidopsis cells. ► Nitrosothiols display apolar motifs not located in close vicinity of cysteines. ► Salt stress alters the endogenous nitrosylation of specific cysteines in Arabidopsis. -- Abstract: S-Nitrosylation emerges as an important protein modification in many processes. However, most data were obtained at the protein level after addition of a NO donor, particularly in plants where information about the cysteines nitrosylated in these proteins is scarce. An adapted work-flow, combining the classical biotin switch method and labeling with isotope-coded affinity tags (ICAT), is proposed. Without addition of NO donor, a total of 53 endogenous nitrosocysteines was identified in Arabidopsis cells, in proteins belonging to all cell territories, including membranes, and covering a large panel of functions. This first repertoire of nitrosothiols in plants enabled also preliminary structural description. Three apolar motifs, not located in close vicinity of cysteines and accounting for half the dataset, were detected and are proposed to complement nitrosylation prediction algorithms, poorly trained with plant data to date. Analysis of changes induced by a brief salt stress showed that NaCl modified the nitrosylation level of a small proportion of endogenously nitrosylated proteins and did not concern all nitrosothiols in these proteins. The possible role of some NO targets in the response to salt stress was discussed.

  2. Intracellular Localization of Arabidopsis Sulfurtransferases1

    Science.gov (United States)

    Bauer, Michael; Dietrich, Christof; Nowak, Katharina; Sierralta, Walter D.; Papenbrock, Jutta

    2004-01-01

    Sulfurtransferases (Str) comprise a group of enzymes widely distributed in archaea, eubacteria, and eukaryota which catalyze the transfer of a sulfur atom from suitable sulfur donors to nucleophilic sulfur acceptors. In all organisms analyzed to date, small gene families encoding Str proteins have been identified. The gene products were localized to different compartments of the cells. Our interest concerns the localization of Str proteins encoded in the nuclear genome of Arabidopsis. Computer-based prediction methods revealed localization in different compartments of the cell for six putative AtStrs. Several methods were used to determine the localization of the AtStr proteins experimentally. For AtStr1, a mitochondrial localization was demonstrated by immunodetection in the proteome of isolated mitochondria resolved by one- and two-dimensional gel electrophoresis and subsequent blotting. The respective mature AtStr1 protein was identified by mass spectrometry sequencing. The same result was obtained by transient expression of fusion constructs with the green fluorescent protein in Arabidopsis protoplasts, whereas AtStr2 was exclusively localized to the cytoplasm by this method. Three members of the single-domain AtStr were localized in the chloroplasts as demonstrated by transient expression of green fluorescent protein fusions in protoplasts and stomata, whereas the single-domain AtStr18 was shown to be cytoplasmic. The remarkable subcellular distribution of AtStr15 was additionally analyzed by transmission electron immunomicroscopy using a monospecific antibody against green fluorescent protein, indicating an attachment to the thylakoid membrane. The knowledge of the intracellular localization of the members of this multiprotein family will help elucidate their specific functions in the organism. PMID:15181206

  3. Gravity-regulated gene expression in Arabidopsis thaliana

    Science.gov (United States)

    Sederoff, Heike; Brown, Christopher S.; Heber, Steffen; Kajla, Jyoti D.; Kumar, Sandeep; Lomax, Terri L.; Wheeler, Benjamin; Yalamanchili, Roopa

    Plant growth and development is regulated by changes in environmental signals. Plants sense environmental changes and respond to them by modifying gene expression programs to ad-just cell growth, differentiation, and metabolism. Functional expression of genes comprises many different processes including transcription, translation, post-transcriptional and post-translational modifications, as well as the degradation of RNA and proteins. Recently, it was discovered that small RNAs (sRNA, 18-24 nucleotides long), which are heritable and systemic, are key elements in regulating gene expression in response to biotic and abiotic changes. Sev-eral different classes of sRNAs have been identified that are part of a non-cell autonomous and phloem-mobile network of regulators affecting transcript stability, translational kinetics, and DNA methylation patterns responsible for heritable transcriptional silencing (epigenetics). Our research has focused on gene expression changes in response to gravistimulation of Arabidopsis roots. Using high-throughput technologies including microarrays and 454 sequencing, we iden-tified rapid changes in transcript abundance of genes as well as differential expression of small RNA in Arabidopsis root apices after minutes of reorientation. Some of the differentially regu-lated transcripts are encoded by genes that are important for the bending response. Functional mutants of those genes respond faster to reorientation than the respective wild type plants, indicating that these proteins are repressors of differential cell elongation. We compared the gravity responsive sRNAs to the changes in transcript abundances of their putative targets and identified several potential miRNA: target pairs. Currently, we are using mutant and transgenic Arabidopsis plants to characterize the function of those miRNAs and their putative targets in gravitropic and phototropic responses in Arabidopsis.

  4. Functional analysis of the Hikeshi-like protein and its interaction with HSP70 in Arabidopsis

    Energy Technology Data Exchange (ETDEWEB)

    Koizumi, Shinya; Ohama, Naohiko; Mizoi, Junya [Laboratory of Plant Molecular Physiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657 (Japan); Shinozaki, Kazuo [RIKEN Plant Science Center, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, Kanagawa 230-0045 (Japan); Yamaguchi-Shinozaki, Kazuko, E-mail: akys@mail.ecc.u-tokyo.ac.jp [Laboratory of Plant Molecular Physiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657 (Japan)

    2014-07-18

    Highlights: • HKL, a Hikeshi homologous gene is identified in Arabidopsis. • HKL interacts with two HSP70 isoforms and regulates the subcellular localization of HSC70-1. • The two HSP70 translocate into nucleus in response to heat stress. • Overexpression of HKL confers thermotolerance in transgenic plants. - Abstract: Heat shock proteins (HSPs) refold damaged proteins and are an essential component of the heat shock response. Previously, the 70 kDa heat shock protein (HSP70) has been reported to translocate into the nucleus in a heat-dependent manner in many organisms. In humans, the heat-induced translocation of HSP70 requires the nuclear carrier protein Hikeshi. In the Arabidopsis genome, only one gene encodes a protein with high homology to Hikeshi, and we named this homolog Hikeshi-like (HKL) protein. In this study, we show that two Arabidopsis HSP70 isoforms accumulate in the nucleus in response to heat shock and that HKL interacts with these HSP70s. Our histochemical analysis revealed that HKL is predominantly expressed in meristematic tissues, suggesting the potential importance of HKL during cell division in Arabidopsis. In addition, we show that HKL regulates HSP70 localization, and HKL overexpression conferred thermotolerance to transgenic Arabidopsis plants. Our results suggest that HKL plays a positive role in the thermotolerance of Arabidopsis plants and cooperatively interacts with HSP70.

  5. Arabidopsis tetraspanins are confined to discrete expression domains and cell types in reproductive tissues and form homo-and heterodimers when expressed in yeast

    Science.gov (United States)

    Tetraspanins are evolutionary conserved transmembrane proteins present in all multicellular organisms. In animals, they are known to act as central organizers of membrane complexes and thought to facilitate diverse biological processes, such as cell proliferation, movement, adhesion, and fusion. The...

  6. The cyclic nucleotide gated cation channel AtCNGC10 traffics from the ER via Golgi vesicles to the plasma membrane of Arabidopsis root and leaf cells

    Directory of Open Access Journals (Sweden)

    Andres Marilou A

    2007-09-01

    Full Text Available Abstract Background The cyclic nucleotide-gated ion channels (CNGCs maintain cation homeostasis essential for a wide range of physiological processes in plant cells. However, the precise subcellular locations and trafficking of these membrane proteins are poorly understood. This is further complicated by a general deficiency of information about targeting pathways of membrane proteins in plants. To investigate CNGC trafficking and localization, we have measured Atcngc5 and Atcngc10 expression in roots and leaves, analyzed AtCNGC10-GFP fusions transiently expressed in protoplasts, and conducted immunofluorescence labeling of protoplasts and immunoelectron microscopic analysis of high pressure frozen leaves and roots. Results AtCNGC10 mRNA and protein levels were 2.5-fold higher in roots than leaves, while AtCNGC5 mRNA and protein levels were nearly equal in these tissues. The AtCNGC10-EGFP fusion was targeted to the plasma membrane in leaf protoplasts, and lightly labeled several intracellular structures. Immunofluorescence microscopy with affinity purified CNGC-specific antisera indicated that AtCNGC5 and AtCNGC10 are present in the plasma membrane of protoplasts. Immunoelectron microscopy demonstrated that AtCNGC10 was associated with the plasma membrane of mesophyll, palisade parenchyma and epidermal cells of leaves, and the meristem, columella and cap cells of roots. AtCNCG10 was also observed in the endoplasmic reticulum and Golgi cisternae and vesicles of 50–150 nm in size. Patch clamp assays of an AtCNGC10-GFP fusion expressed in HEK293 cells measured significant cation currents. Conclusion AtCNGC5 and AtCNGC10 are plasma membrane proteins. We postulate that AtCNGC10 traffics from the endoplasmic reticulum via the Golgi apparatus and associated vesicles to the plasma membrane. The presence of the cation channel, AtCNGC10, in root cap meristem cells, cell plate, and gravity-sensing columella cells, combined with the previously reported

  7. Visualization of phosphatidylinositol 4,5-bisphosphate in the plasma membrane of suspension-cultured tobacco BY-2 cells and whole Arabidopsis seedlings

    NARCIS (Netherlands)

    Leeuwen, van W.; Vermeer, J.E.M.; Gadella, T.W.J.; Munnik, T.

    2007-01-01

    Phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P-2] is an important signalling lipid in mammalian cells, where it functions as a second-messenger precursor in response to agonist-dependent activation of phospholipase C (PLC) but also operates as a signalling molecule on its own. Much of the

  8. Green fluorescent protein-mtalin causes defects in actin organization and cell expansion in Arabidopsis and inhibits actin depolymerizing factor's actin depolymerizing activity in vitro

    NARCIS (Netherlands)

    Ketelaar, T.; Anthony, R.G.; Hussey, P.J.

    2004-01-01

    Expression of green fluorescent protein (GFP) linked to an actin binding domain is a commonly used method for live cell imaging of the actin cytoskeleton. One of these chimeric proteins is GFP-mTalin (GFP fused to the actin binding domain of mouse talin). Although it has been demonstrated that

  9. Light responses in Photoperiodism in Arabidopsis thaliana

    Energy Technology Data Exchange (ETDEWEB)

    Anthony R. Cashmore

    2006-08-01

    domains. It is this cysteine residue that forms a covalent adduct with the bound flavin in the photocycle of PHOT1 and FKF1. In the mutant ADO1 this cysteine is replaced by an alanine. We argue that if ADO1 functions as a photoreceptor in a similar fashion to PHOT1, then this mutant ADO1 should not be able to rescue the altered circadian phenotype of ado1 mutant plants. We find under white light, that indeed this is the case. Experiments underway are aimed at determining if the altered circadian phenotype under blue and red light are similarly unable to be rescued by the mutant gene, and we are performing similar experiments under red light with respect to the defect in hypocotyl elongation. The results from these experiments will likely support the hypothesis that ADO1 functions as a blue light photoreceptor, and they will address the question concerning whether or not the altered properties of the ado1 mutant under red light are also a reflection of this photoreceptor function. References. Briggs, W. R., Beck, C. F., Cashmore, A. R., Christie, J. M., Hughes, J., Jarillo, J. A., Kagawa, T., Kanegae, H., Liscum, E., Nagatani, A., et al. (2001). The phototropin family of photoreceptors. Plant Cell 13, 993-997. Christie, J. M., Reymond, P., Powell, G. K., Bernasconi, P., Raibekas, A. A., Liscum, E., and Briggs, W. R. (1998). Arabidopsis NPH1: A flavoprotein with the properties of a photoreceptor for phototropism. Science 282, 1698-1701. Froehlich, A. C., Liu, Y., Loros, J. J., and Dunlap, J. C. (2002). White Collar-1, a circadian blue light photoreceptor, binding to the frequency promoter. Science 297, 815-819. Imaizumi, T., Tran, H. G., Swartz, T. E., Briggs, W. R., and Kay, S. A. (2003). FKF1 is essential for photoperiodic-specific light signalling in Arabidopsis. Nature 426, 302-306. Jarillo, J. A., Capel, J., Tang, R.-H., Yang, H.-Q., Alonso, J. M., Ecker, J. R., and Cashmore, A. R. (2001a). An Arabidopsis circadian clock component interacts with both CRY1 and phy

  10. Arabidopsis thickvein mutation affects vein thickness and organ vascularization, and resides in a provascular cell-specific spermine synthase involved in vein definition and in polar auxin transport.

    Science.gov (United States)

    Clay, Nicole K; Nelson, Timothy

    2005-06-01

    Polar auxin transport has been implicated in the induction of vascular tissue and in the definition of vein positions. Leaves treated with chemical inhibitors of polar auxin transport exhibited vascular phenotypes that include increased vein thickness and vascularization. We describe a recessive mutant, thickvein (tkv), which develops thicker veins in leaves and in inflorescence stems. The increased vein thickness is attributable to an increased number of vascular cells. Mutant plants have smaller leaves and shorter inflorescence stems, and this reduction in organ size and height is accompanied by an increase in organ vascularization, which appears to be attributable to an increase in the recruitment of cells into veins. Furthermore, although floral development is normal, auxin transport in the inflorescence stem is significantly reduced in the mutant, suggesting that the defect in auxin transport is responsible for the vascular phenotypes. In the primary root, the veins appear morphologically normal, but root growth in the tkv mutant is hypersensitive to exogenous cytokinin. The tkv mutation was found to reside in the ACL5 gene, which encodes a spermine synthase and whose expression is specific to provascular cells. We propose that ACL5/TKV is involved in vein definition (defining the boundaries between veins and nonvein regions) and in polar auxin transport, and that polyamines are involved in this process.

  11. Using "Arabidopsis" Genetic Sequences to Teach Bioinformatics

    Science.gov (United States)

    Zhang, Xiaorong

    2009-01-01

    This article describes a new approach to teaching bioinformatics using "Arabidopsis" genetic sequences. Several open-ended and inquiry-based laboratory exercises have been designed to help students grasp key concepts and gain practical skills in bioinformatics, using "Arabidopsis" leucine-rich repeat receptor-like kinase (LRR…

  12. Reference: 255 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available ases, AtIPK1 and AtIPK2beta, for the later steps of phytate synthesis in Arabidopsis thaliana. Coincident disruption...olyphosphate kinases in phosphate signaling biology. Generation of phytate-free seeds in Arabidopsis through disruption

  13. Arabidopsis CDS blastp result: AK108458 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK108458 002-143-D05 At4g35000.1 L-ascorbate peroxidase 3 (APX3) identical to ascorbat...e peroxidase 3 [Arabidopsis thaliana] GI:2444019, L-ascorbate peroxidase [Arabidopsis thaliana] gi|152379...1|emb|CAA66926; similar to ascorbate peroxidase [Gossypium hirsutum] gi|1019946|gb|AAB52954 2e-35 ...

  14. Arabidopsis CDS blastp result: AK070842 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK070842 J023074O14 At4g35000.1 L-ascorbate peroxidase 3 (APX3) identical to ascorbat...e peroxidase 3 [Arabidopsis thaliana] GI:2444019, L-ascorbate peroxidase [Arabidopsis thaliana] gi|1523791...|emb|CAA66926; similar to ascorbate peroxidase [Gossypium hirsutum] gi|1019946|gb|AAB52954 1e-112 ...

  15. G2 Checkpoint Responses in Arabidopsis

    Energy Technology Data Exchange (ETDEWEB)

    Britt, Anne [Univ. of California, Davis, CA (United States)

    2013-03-18

    This project focused on the mechanism and biological significance of the G2 arrest response to replication stress in plants. We employed both forward and reverse genetic approaches to identify genes required for this response. A total of 3 different postdocs, 5 undergraduates, and 2 graduate students participated in the project. We identified several genes required for damage response in plants, including homologs of genes previously identified in animals (ATM and ATR), novel, a plant-specific genes (SOG1) and a gene known in animals but previously thought to be missing from the Arabidopsis genome (ATRIP). We characterized the transcriptome of gamma-irradiated plants, and found that plants, unlike animals, express a robust transcriptional response to damage, involving genes that regulate the cell cycle and DNA metabolism. This response requires both ATM and the transcription factor SOG1. We found that both ATM and ATR play a role in meiosis in plants. We also found that plants have a cell-type-specific programmed cell death response to ionizing radiation and UV light, and that this response requires ATR, ATM, and SOG1. These results were published in a series of 5 papers.

  16. Arabidopsis CPR5 regulates ethylene signaling via molecular association with the ETR1 receptor.

    Science.gov (United States)

    Wang, Feifei; Wang, Lijuan; Qiao, Longfei; Chen, Jiacai; Pappa, Maria Belen; Pei, Haixia; Zhang, Tao; Chang, Caren; Dong, Chun-Hai

    2017-11-01

    The plant hormone ethylene plays various functions in plant growth, development and response to environmental stress. Ethylene is perceived by membrane-bound ethylene receptors, and among the homologous receptors in Arabidopsis, the ETR1 ethylene receptor plays a major role. The present study provides evidence demonstrating that Arabidopsis CPR5 functions as a novel ETR1 receptor-interacting protein in regulating ethylene response and signaling. Yeast split ubiquitin assays and bi-fluorescence complementation studies in plant cells indicated that CPR5 directly interacts with the ETR1 receptor. Genetic analyses indicated that mutant alleles of cpr5 can suppress ethylene insensitivity in both etr1-1 and etr1-2, but not in other dominant ethylene receptor mutants. Overexpression of Arabidopsis CPR5 either in transgenic Arabidopsis plants, or ectopically in tobacco, significantly enhanced ethylene sensitivity. These findings indicate that CPR5 plays a critical role in regulating ethylene signaling. CPR5 is localized to endomembrane structures and the nucleus, and is involved in various regulatory pathways, including pathogenesis, leaf senescence, and spontaneous cell death. This study provides evidence for a novel regulatory function played by CPR5 in the ethylene receptor signaling pathway in Arabidopsis. © 2017 Institute of Botany, Chinese Academy of Sciences.

  17. AHP2, AHP3, and AHP5 act downstream of CKI1 in Arabidopsis female gametophyte development.

    Science.gov (United States)

    Liu, Zhenning; Yuan, Li; Song, Xiaoya; Yu, Xiaolin; Sundaresan, Venkatesan

    2017-06-15

    Histidine phosphotransfer proteins (HPs) are key elements of the two-component signaling system, which act as a shuttle to transfer phosphorylation signals from histidine kinases (HKs) to response regulators (RRs). CYTOKININ INDEPENDENT 1 (CKI1), a key regulator of central cell specification in the Arabidopsis female gametophyte, activates the cytokinin signaling pathway through the Arabidopsis histidine phosphotransfer proteins (AHPs). There are five HP genes in Arabidopsis, AHP1-AHP5, but it remains unknown which AHP genes act downstream of CKI1 in Arabidopsis female gametophyte development. Promoter activity analysis of AHP1-AHP5 in embryo sacs revealed AHP1, AHP2, AHP3, and AHP5 expression in the central cell. Phenotypic studies of various combinations of ahp mutants showed that triple mutations in AHP2, AHP3, and AHP5 resulted in defective embryo sac development. Using cell-specific single and double markers in the female gametophyte, the ahp2-2 ahp3 ahp5-2/+ triple mutant ovules showed loss of central cell and antipodal cell fates and gain of egg cell or synergid cell attributes, resembling the cki1 mutant phenotypes. These data suggest that AHP2, AHP3, and AHP5 are the major factors acting downstream of CKI1 in the two-component cytokinin signaling pathway to promote Arabidopsis female gametophyte development. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  18. Ion Exchangers NHX1 and NHX2 Mediate Active Potassium Uptake into Vacuoles to Regulate Cell Turgor and Stomatal Function in Arabidopsis[W][OA

    Science.gov (United States)

    Barragán, Verónica; Leidi, Eduardo O.; Andrés, Zaida; Rubio, Lourdes; De Luca, Anna; Fernández, José A.; Cubero, Beatriz; Pardo, José M.

    2012-01-01

    Intracellular NHX proteins are Na+,K+/H+ antiporters involved in K+ homeostasis, endosomal pH regulation, and salt tolerance. Proteins NHX1 and NHX2 are the two major tonoplast-localized NHX isoforms. Here, we show that NHX1 and NHX2 have similar expression patterns and identical biochemical activity, and together they account for a significant amount of the Na+,K+/H+ antiport activity in tonoplast vesicles. Reverse genetics showed functional redundancy of NHX1 and NHX2 genes. Growth of the double mutant nhx1 nhx2 was severely impaired, and plants were extremely sensitive to external K+. By contrast, nhx1 nhx2 mutants showed similar sensitivity to salinity stress and even greater rates of Na+ sequestration than the wild type. Double mutants had reduced ability to create the vacuolar K+ pool, which in turn provoked greater K+ retention in the cytosol, impaired osmoregulation, and compromised turgor generation for cell expansion. Genes NHX1 and NHX2 were highly expressed in guard cells, and stomatal function was defective in mutant plants, further compromising their ability to regulate water relations. Together, these results show that tonoplast-localized NHX proteins are essential for active K+ uptake at the tonoplast, for turgor regulation, and for stomatal function. PMID:22438021

  19. Similarities between Reproductive and Immune Pistil Transcriptomes of Arabidopsis Species.

    Science.gov (United States)

    Mondragón-Palomino, Mariana; John-Arputharaj, Ajay; Pallmann, Maria; Dresselhaus, Thomas

    2017-07-01

    Independent lines of evidence suggest that members from ancient and polymorphic gene families such as defensins and receptor-like kinases mediate intercellular communication during both the immune response and reproduction. Here, we report a large-scale analysis to investigate the extent of overlap between these processes by comparing differentially expressed genes (DEGs) in the pistil transcriptomes of Arabidopsis thaliana and Arabidopsis halleri during self-pollination and interspecific pollination and during infection with Fusarium graminearum In both Arabidopsis species, the largest number of DEGs was identified in infected pistils, where genes encoding regulators of cell division and development were most frequently down-regulated. Comparison of DEGs between infection and various pollination conditions showed that up to 79% of down-regulated genes are shared between conditions and include especially defensin-like genes. Interspecific pollination of A. thaliana significantly up-regulated thionins and defensins. The significant overrepresentation of similar groups of DEGs in the transcriptomes of reproductive and immune responses of the pistil makes it a prime system in which to study the consequences of plant-pathogen interactions on fertility and the evolution of intercellular communication in pollination. © 2017 American Society of Plant Biologists. All Rights Reserved.

  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.

  1. Cuticle ultrastructure, cuticular lipid composition, and gene expression in hypoxia-stressed Arabidopsis stems and leaves.

    Science.gov (United States)

    Kim, Hyojin; Choi, Dongsu; Suh, Mi Chung

    2017-06-01

    An increased permeability of the cuticle is closely associated with downregulation of genes involved in cuticular lipid synthesis in hypoxia-stressed Arabidopsis and may allow plants to cope with oxygen deficiency. The hydrophobic cuticle layer consisting of cutin polyester and cuticular wax is the first barrier to protect the aerial parts of land plants from environmental stresses. In the present study, we investigated the role of cuticle membrane in Arabidopsis responses to oxygen deficiency. TEM analysis showed that the epidermal cells of hypoxia-treated Arabidopsis stems and leaves possessed a thinner electron-translucent cuticle proper and a more electron-dense cuticular layer. A reduction in epicuticular wax crystal deposition was observed in SEM images of hypoxia-treated Arabidopsis stem compared with normoxic control. Cuticular transpiration was more rapid in hypoxia-stressed leaves than in normoxic control. Total wax and cutin loads decreased by approximately 6-12 and 12-22%, respectively, and the levels of C29 alkanes, secondary alcohols, and ketones, C16:0 ω-hydroxy fatty acids, and C18:2 dicarboxylic acids were also prominently reduced in hypoxia-stressed Arabidopsis leaves and/or stems relative to normoxic control. Genome-wide transcriptome and quantitative RT-PCR analyses revealed that the expression of several genes involved in the biosynthesis and transport of cuticular waxes and cutin monomers were downregulated more than fourfold, but no significant alterations were detected in the transcript levels of fatty acid biosynthetic genes, BCCP2, PDH-E1α, and ENR1 in hypoxia-treated Arabidopsis stems and leaves compared with normoxic control. Taken together, an increased permeability of the cuticle is closely associated with downregulation of genes involved in cuticular lipid synthesis in hypoxia-stressed Arabidopsis. The present study elucidates one of the cuticle-related adaptive responses that may allow plants to cope with low oxygen levels.

  2. PNL1 and PNL2 : Arabidopsis homologs of maize PAN1

    OpenAIRE

    Clark, Lauren Gail

    2010-01-01

    PNL1 and PNL2 are the closest Arabidopsis relatives of maize pan1. pan1 and the PNL family of 11 genes encode leucine-rich repeat, receptor-like kinases, however none of these putative kinases is predicted to have actual kinase function, due to one or more amino acid substitutions in residues necessary for kinase function. Because PAN1 plays a role in subsidiary cell formation in maize, it is hypothesized that PNL1 and PNL2 are involved in stomatal formation in Arabidopsis. YFP fusions of the...

  3. Arabidopsis NATA1 Acetylates Putrescine and Decreases Defense-Related Hydrogen Peroxide Accumulation1[OPEN

    Science.gov (United States)

    Preuss, Aileen S.

    2016-01-01

    Biosynthesis of the polyamines putrescine, spermidine, and spermine is induced in response to pathogen infection of plants. Putrescine, which is produced from Arg, serves as a metabolic precursor for longer polyamines, including spermidine and spermine. Polyamine acetylation, which has important regulatory functions in mammalian cells, has been observed in several plant species. Here we show that Arabidopsis (Arabidopsis thaliana) N-ACETYLTRANSFERASE ACTIVITY1 (NATA1) catalyzes acetylation of putrescine to N-acetylputrescine and thereby competes with spermidine synthase for a common substrate. NATA1 expression is strongly induced by the plant defense signaling molecule jasmonic acid and coronatine, an effector molecule produced by DC3000, a Pseudomonas syringae strain that initiates a virulent infection in Arabidopsis ecotype Columbia-0. DC3000 growth is reduced in nata1 mutant Arabidopsis, suggesting a role for NATA1-mediated putrescine acetylation in suppressing antimicrobial defenses. During infection by P. syringae and other plant pathogens, polyamine oxidases use spermidine and spermine as substrates for the production of defense-related H2O2. Compared to wild-type Columbia-0 Arabidopsis, the response of nata1mutants to P. syringae infection includes reduced accumulation of acetylputrescine, greater abundance of nonacetylated polyamines, elevated H2O2 production by polyamine oxidases, and higher expression of genes related to pathogen defense. Together, these results are consistent with a model whereby P. syringae growth is improved in a targeted manner through coronatine-induced putrescine acetylation by NATA1. PMID:27208290

  4. Multi-element bioimaging of Arabidopsis thaliana roots

    DEFF Research Database (Denmark)

    Persson, Daniel Olof; Chen, Anle; Aarts, Mark G.M.

    2016-01-01

    Better understanding of root function is central for the development of plants with more efficient nutrient uptake and translocation. We here present a method for multielement bioimaging at the cellular level in roots of the genetic model system Arabidopsis (Arabidopsis thaliana). Using conventio......Better understanding of root function is central for the development of plants with more efficient nutrient uptake and translocation. We here present a method for multielement bioimaging at the cellular level in roots of the genetic model system Arabidopsis (Arabidopsis thaliana). Using...... omics techniques. To demonstrate the potential of the method, we analyzed a mutant of Arabidopsis unable to synthesize the metal chelator nicotianamine. The mutant accumulated substantially more zinc and manganese than the wild type in the tissues surrounding the vascular cylinder. For iron, the images...... looked completely different, with iron bound mainly in the epidermis of the wild-type plants but confined to the cortical cell walls of the mutant. The method offers the power of inductively coupled plasma-mass spectrometry to be fully employed, thereby providing a basis for detailed studies of ion...

  5. Dynamics of cell wall elasticity pattern shapes the cell during yeast mating morphogenesis

    Science.gov (United States)

    Goldenbogen, Björn; Giese, Wolfgang; Hemmen, Marie; Uhlendorf, Jannis; Herrmann, Andreas

    2016-01-01

    The cell wall defines cell shape and maintains integrity of fungi and plants. When exposed to mating pheromone, Saccharomyces cerevisiae grows a mating projection and alters in morphology from spherical to shmoo form. Although structural and compositional alterations of the cell wall accompany shape transitions, their impact on cell wall elasticity is unknown. In a combined theoretical and experimental approach using finite-element modelling and atomic force microscopy (AFM), we investigated the influence of spatially and temporally varying material properties on mating morphogenesis. Time-resolved elasticity maps of shmooing yeast acquired with AFM in vivo revealed distinct patterns, with soft material at the emerging mating projection and stiff material at the tip. The observed cell wall softening in the protrusion region is necessary for the formation of the characteristic shmoo shape, and results in wider and longer mating projections. The approach is generally applicable to tip-growing fungi and plants cells. PMID:27605377

  6. Putrescine overproduction does not affect the catabolism of spermidine and spermine in poplar and Arabidopsis

    Science.gov (United States)

    Lin Shao; Pratiksha Bhatnagar; Rajtilak Majumdar; Rakesh Minocha; Subhash C. Minocha

    2014-01-01

    The effect of up-regulation of putrescine (Put) production by genetic manipulation on the turnover of spermidine (Spd) and spermine (Spm) was investigated in transgenic cells of poplar (Populus nigra x maximowiczii) and seedlings of Arabidopsis thaliana. Several-fold increase in Put production was achieved by expressing a mouse...

  7. Effect of nickel chloride on Arabidopsis genomic DNA and methylation of 18S rDNA

    Directory of Open Access Journals (Sweden)

    Zhongai Li

    2015-01-01

    Conclusions: NiCl2 application caused variation of DNA methylation of the Arabidopsis genomic and offspring's. NiCl2 also resulted in nucleolar injury and deformity of root tip cells. The methylation rate of 18S rDNA also changed by adding NiCl2.

  8. Embryonic origin of the Arabidopsis primary root and root meristem initials

    NARCIS (Netherlands)

    Scheres, B.J.G.; Wolkenfelt, H.; Willemsen, V.; Terlouw, M.; Lawson, E.; Dean, C.; Weisbeek, P.

    1994-01-01

    The embryonic origin of the Arabidopsis root and hypocotyl region has been investigated using histological techniques and clonal analysis. Our data reveal the pattern of cell division in the embryo giving rise to the various initials within the root promeristem. A small region of the root at its

  9. Proteomic identification of early salicylate- and flg22-responsive redox-sensitive proteins in Arabidopsis

    KAUST Repository

    Liu, Peng; Zhang, Huoming; Yu, Boying; Xiong, Liming; Xia, Yiji

    2015-01-01

    in Arabidopsis cells during the early response to salicylate or flg22, two defense pathway elicitors that are known to disturb cellular redox homeostasis. Among the salicylate- and/or flg22-responsive redox-sensitive proteins are those involved in transcriptional

  10. Mutations affecting the radial organisation of the Arabidopsis root display specific defects throughout the embryonic axis

    NARCIS (Netherlands)

    Scheres, B.J.G.; Di Laurenzio, L.; Willemsen, V.; Hauser, M.-T.; Janmaat, K.; Benfey, P.N.

    1995-01-01

    The primary root of Arabidopsis thaliana has a remarkably uniform cellular organisation. The fixed radial pattern of cell types in the mature root arises from proliferative divisions within the root meristem. The root meristem, in turn, is laid down during embryogenesis. We have analysed six

  11. Arabidopsis dynamin-related protein 1A polymers bind, but do not tubulate, liposomes

    International Nuclear Information System (INIS)

    Backues, Steven K.; Bednarek, Sebastian Y.

    2010-01-01

    The Arabidopsis dynamin-related protein 1A (AtDRP1A) is involved in endocytosis and cell plate maturation in Arabidopsis. Unlike dynamin, AtDRP1A does not have any recognized membrane binding or protein-protein interaction domains. We report that GTPase active AtDRP1A purified from Escherichia coli as a fusion to maltose binding protein forms homopolymers visible by negative staining electron microscopy. These polymers interact with protein-free liposomes whose lipid composition mimics that of the inner leaflet of the Arabidopsis plasma membrane, suggesting that lipid-binding may play a role in AtDRP1A function. However, AtDRP1A polymers do not appear to assemble and disassemble in a dynamic fashion and do not have the ability to tubulate liposomes in vitro, suggesting that additional factors or modifications are necessary for AtDRP1A's in vivo function.

  12. An early nodulin-like protein accumulates in the sieve element plasma membrane of Arabidopsis

    DEFF Research Database (Denmark)

    Khan, Junaid A.; Wang, Qi; Sjölund, Richard D.

    2007-01-01

    Membrane proteins within the sieve element-companion cell complex have essential roles in the physiological functioning of the phloem. The monoclonal antibody line RS6, selected from hybridomas raised against sieve elements isolated from California shield leaf (Streptanthus tortuosus; Brassicaceae...... was revealed by reverse transcription-PCR of Arabidopsis leaf RNA using degenerate primers to be an early nodulin (ENOD)-like protein that is encoded by the expressed gene At3g20570. Arabidopsis ENOD-like proteins are encoded by a multigene family composed of several types of structurally related phytocyanins...... from the precursor protein, resulting in a mature peptide of approximately 15 kD that is attached to the sieve element plasma membrane via a carboxy-terminal glycosylphosphatidylinositol membrane anchor. Many of the Arabidopsis ENOD-like proteins accumulate in gametophytic tissues, whereas in both...

  13. Identifying the transition to the maturation zone in three ecotypes of Arabidopsis thaliana roots.

    Science.gov (United States)

    Cajero Sánchez, Wendy; García-Ponce, Berenice; Sánchez, María de la Paz; Álvarez-Buylla, Elena R; Garay-Arroyo, Adriana

    2018-01-01

    The Arabidopsis thaliana (hereafter Arabidopsis) root has become a useful model for studying how organ morphogenesis emerge from the coordination and balance of cell proliferation and differentiation, as both processes may be observed and quantified in the root at different stages of development. Hence, being able to objectively identify and delimit the different stages of root development has been very important. Up to now, three different zones along the longitudinal axis of the primary root of Arabidopsis, have been identified: the root apical meristematic zone (RAM) with two domains [the proliferative (PD) and the transition domain (TD)], the elongation zone (EZ) and the maturation zone (MZ). We previously reported a method to quantify the length of the cells of the meristematic and the elongation zone, as well as the boundaries or transitions between the root domains along the growing part of the Arabidopsis root. In this study, we provide a more accurate criterion to identify the MZ. Traditionally, the transition between the EZ to the MZ has been established by the emergence of the first root-hair bulge in the epidermis, because this emergence coincides with cell maturation in this cell type. But we have found here that after the emergence of the first root-hair bulge some cells continue to elongate and we have confirmed this in three different Arabidopsis ecotypes. We established the limit between the EZ and the MZ by looking for the closest cortical cell with a longer length than the average cell length of 10 cells after the cortical cell closest to the epidermal cell with the first root-hair bulge in these three ecotypes. In Col-0 and Ws this cell is four cells above the one with the root hair bulge and, in the Ler ecotype, this cell is five cells above. To unambiguously identifying the site at which cells stop elongating and attain their final length and fate at the MZ, we propose to calculate the length of completely elongated cortical cells counting 10

  14. Kinome profiling of Arabidopsis using arrays of kinase consensus substrates

    Directory of Open Access Journals (Sweden)

    Pieterse Corné MJ

    2007-02-01

    Full Text Available Abstract Background Kinome profiling aims at the parallel analysis of kinase activities in a cell. Novel developed arrays containing consensus substrates for kinases are used to assess those kinase activities. The arrays described in this paper were already used to determine kinase activities in mammalian systems, but since substrates from many organisms are present we decided to test these arrays for the determination of kinase activities in the model plant species Arabidopsis thaliana. Results Kinome profiling using Arabidopsis cell extracts resulted in the labelling of many consensus peptides by kinases from the plant, indicating the usefulness of this kinome profiling tool for plants. Method development showed that fresh and frozen plant material could be used to make cell lysates containing active kinases. Dilution of the plant extract increased the signal to noise ratio and non-radioactive ATP enhances full development of spot intensities. Upon infection of Arabidopsis with an avirulent strain of the bacterial pathogen Pseudomonas syringae pv. tomato, we could detect differential kinase activities by measuring phosphorylation of consensus peptides. Conclusion We show that kinome profiling on arrays with consensus substrates can be used to monitor kinase activities in plants. In a case study we show that upon infection with avirulent P. syringae differential kinase activities can be found. The PepChip can for example be used to purify (unknown kinases that play a role in P. syringae infection. This paper shows that kinome profiling using arrays of consensus peptides is a valuable new tool to study signal-transduction in plants. It complements the available methods for genomics and proteomics research.

  15. Characterization Of Laccase T-DNA Mutants In Arabidopsis thaliana

    DEFF Research Database (Denmark)

    Andersen, Jeppe Reitan; Asp, Torben; Mansfield, Shawn

    2009-01-01

    Laccases (P-diphenol:O2 oxidoreductase; EC 1.10.3.2), also termed laccase-like multicopper oxidases, are blue copper-containing oxidases which comprise multigene families in plants. In the Arabidopsis thaliana genome, 17 laccase genes (LAC1 to LAC17) have been annotated. To identify laccases...... for LAC15 T-DNA mutant seeds and an approximate 24 hour delay in germination was observed for these seeds. An approximate 20% reduction in glucose, galactose, and xylose was observed in primary stem cell walls of the LAC2 T-DNA mutants while similar relative increases in xylose were observed for LAC8...

  16. Sulfinylated Azadecalins act as functional mimics of a pollen germination stimulant in Arabidopsis pistils

    Science.gov (United States)

    Qin, Yuan; Wysocki, Ronald J; Somogyi, Arpad; Feinstein, Yelena; Franco, Jessica Y; Tsukamoto, Tatsuya; Dunatunga, Damayanthi; Levy, Clara; Smith, Steven; Simpson, Robert; Gang, David; Johnson, Mark A; Palanivelu, Ravishankar

    2011-01-01

    SUMMARY Polarized cell elongation is triggered by small molecule cues during development of diverse organisms. During plant reproduction, pollen interactions with the stigma result in the polar outgrowth of a pollen tube, which delivers sperm cells to the female gametophyte to effect double fertilization. In many plants, pistils stimulate pollen germination. However, in Arabidopsis, the effect of pistils on pollen germination and the pistil factors that stimulate pollen germination remain poorly characterized. Here, we demonstrate that stigma, style, and ovules in Arabidopsis pistils stimulate pollen germination. We isolated an Arabidopsis pistil extract fraction that stimulates Arabidopsis pollen germination, and employed ultrahigh resolution ESI FT-ICR and MS/MS techniques to accurately determine the mass (202.126 daltons) of a compound that is specifically present in this pistil extract fraction. Using the molecular formula (C10H19NOS) and tandem mass spectral fragmentation patterns of the m/z (mass to charge ratio) 202.126 ion, we postulated chemical structures, devised protocols, synthesized N-Methanesulfinyl 1- and 2-azadecalins that are close structural mimics of the m/z 202.126 ion, and showed that they are sufficient to stimulate Arabidopsis pollen germination in vitro (30 µM stimulated ~50% germination) and elicit accession-specific response. Although N-Methanesulfinyl 2-azadecalin stimulated pollen germination in three species of Lineage I of Brassicaceae, it did not induce a germination response in Sisymbrium irio (Lineage II of Brassicaceae) and tobacco, indicating that activity of the compound is not random. Our results show that Arabidopsis pistils promote germination by producing azadecalin-like molecules to ensure rapid fertilization by the appropriate pollen. PMID:21801250

  17. Increased root hair density by loss of WRKY6 in Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Markus G. Stetter

    2017-01-01

    Full Text Available Root hairs are unicellular elongations of certain rhizodermal cells that improve the uptake of sparingly soluble and immobile soil nutrients. Among different Arabidopsis thaliana genotypes, root hair density, length and the local acclimation to low inorganic phosphate (Pi differs considerably, when analyzed on split agar plates. Here, genome-wide association fine mapping identified significant single nucleotide polymorphisms associated with the increased root hair density in the absence of local phosphate on chromosome 1. A loss-of-functionmutant of the candidate transcription factor gene WRKY6, which is involved in the acclimation of plants to low phosphorus, had increased root hair density. This is partially explained by a reduced cortical cell diameter in wrky6-3, reducing the rhizodermal cell numbers adjacent to the cortical cells. As a consequence, rhizodermal cells in positions that are in contact with two cortical cells are found more often, leading to higher hair density. Distinct cortical cell diameters and epidermal cell lengths distinguish other Arabidopsis accessions with distinct root hair density and −Pi response from diploid Col-0, while tetraploid Col-0 had generally larger root cell sizes, which explain longer hairs. A distinct radial root morphology within Arabidopsis accessions and wrky6-3explains some, but not all, differences in the root hair acclimation to –Pi.

  18. Reference: 21 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available ication of a number of mutant lines with altered Chl fluorescence characteristics. Analysis of photosynthesis...cation of mutants of Arabidopsis defective in acclimation of photosynthesis to th

  19. Reference: 789 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available ylakoid membranes. Microarray analysis of the chl27-t mutant showed repression of numerous nuclear genes involved in photosynthesis...d CHL27 proteins. Role of Arabidopsis CHL27 protein for photosynthesis, chloroplast development and gene exp

  20. Reference: 306 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available of the endoreduplication cycle in Arabidopsis requires a plant homologue of archaeal DNA topoisomerase (topo) VI. To further understa...nd how DNA is endoreduplicated and how this process is r

  1. Reference: 150 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available ridization, Pht1;4 was found mainly expressed in inorgan...physiological characterization of Arabidopsis pht1;4 high affinity phosphate transporter mutants. Using GUS-gene trap and in situ hyb

  2. Arabidopsis CDS blastp result: AK099152 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK099152 J023070H02 At4g01900.1 P II nitrogen sensing protein (GLB I) identical to P II nitrogen... sensing protein GLB I (GI:7268574) [Arabidopsis thaliana]; similar to nitrogen regulatory prot

  3. Arabidopsis CDS blastp result: AK068407 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK068407 J013149B08 At4g01900.1 P II nitrogen sensing protein (GLB I) identical to P II nitrogen... sensing protein GLB I (GI:7268574) [Arabidopsis thaliana]; similar to nitrogen regulatory prot

  4. Arabidopsis CDS blastp result: AK241043 [KOME

    Lifescience Database Archive (English)

    Full Text Available upted by a stop codon, creating non-consensus donor and acceptor splice sites. 2e-41 ... ...tical to SP|P92997 Germin-like protein subfamily 1 member 13 precursor {Arabidopsis thaliana}; exon 2 interr

  5. Arabidopsis CDS blastp result: AK243135 [KOME

    Lifescience Database Archive (English)

    Full Text Available upted by a stop codon, creating non-consensus donor and acceptor splice sites. 7e-43 ... ...tical to SP|P92997 Germin-like protein subfamily 1 member 13 precursor {Arabidopsis thaliana}; exon 2 interr

  6. Reference: 346 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available th a function in purine turnover in Arabidopsis. To our knowledge this is the fir...ock in allantoate catabolism. AtAAH transcript was detected in all tissues examined by RT-PCR, consistent wi

  7. Reference: 510 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available in support of PSII activity, whereas the interaction of PsbO2 with PSII regulates the turnover... its degradation. The Arabidopsis PsbO2 protein regulates dephosphorylation and turnover of the photosystem

  8. Reference: 278 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available functional ERA1 gene, which encodes the beta-subunit of protein farnesyltransferase (PFT), exhibit pleiotropic effects...gnaling and meristem development. Here, we report the effects of T-DNA insertion mutations in the Arabidopsi

  9. Arabidopsis CDS blastp result: AK287673 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK287673 J065121E18 At4g37750.1 68417.m05344 ovule development protein aintegumenta... (ANT) identical to ovule development protein aintegumenta (ANT) (GI:1244708) ) [Arabidopsis thaliana] 6e-17 ...

  10. Arabidopsis CDS blastp result: AK241272 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK241272 J065132I19 At4g37750.1 68417.m05344 ovule development protein aintegumenta... (ANT) identical to ovule development protein aintegumenta (ANT) (GI:1244708) ) [Arabidopsis thaliana] 1e-88 ...

  11. Arabidopsis CDS blastp result: AK241712 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK241712 J065197H24 At4g37750.1 68417.m05344 ovule development protein aintegumenta... (ANT) identical to ovule development protein aintegumenta (ANT) (GI:1244708) ) [Arabidopsis thaliana] 6e-27 ...

  12. Arabidopsis CDS blastp result: AK106306 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK106306 002-101-C10 At4g37750.1 ovule development protein aintegumenta (ANT) ident...ical to ovule development protein aintegumenta (ANT) (GI:1244708) ) [Arabidopsis thaliana] 3e-89 ...

  13. Arabidopsis CDS blastp result: AK287726 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK287726 J065138E17 At4g37750.1 68417.m05344 ovule development protein aintegumenta... (ANT) identical to ovule development protein aintegumenta (ANT) (GI:1244708) ) [Arabidopsis thaliana] 1e-88 ...

  14. Arabidopsis CDS blastp result: AK109848 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK109848 002-148-F05 At4g37750.1 ovule development protein aintegumenta (ANT) ident...ical to ovule development protein aintegumenta (ANT) (GI:1244708) ) [Arabidopsis thaliana] 5e-73 ...

  15. Arabidopsis CDS blastp result: AK242387 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK242387 J080051E14 At4g37750.1 68417.m05344 ovule development protein aintegumenta... (ANT) identical to ovule development protein aintegumenta (ANT) (GI:1244708) ) [Arabidopsis thaliana] 2e-45 ...

  16. Arabidopsis CDS blastp result: AK240892 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK240892 J065030K10 At4g37750.1 68417.m05344 ovule development protein aintegumenta... (ANT) identical to ovule development protein aintegumenta (ANT) (GI:1244708) ) [Arabidopsis thaliana] 5e-88 ...

  17. Arabidopsis CDS blastp result: AK242957 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK242957 J090089I15 At4g37750.1 68417.m05344 ovule development protein aintegumenta... (ANT) identical to ovule development protein aintegumenta (ANT) (GI:1244708) ) [Arabidopsis thaliana] 1e-28 ...

  18. Arabidopsis CDS blastp result: AK287621 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK287621 J065066I09 At4g37750.1 68417.m05344 ovule development protein aintegumenta... (ANT) identical to ovule development protein aintegumenta (ANT) (GI:1244708) ) [Arabidopsis thaliana] 5e-85 ...

  19. Reference: 627 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available omal processing protease (GPP) from the fat-storing cotyledons of watermelon (Citrullus vulgaris) by column ...ptidase, and a Lon-protease. Specific antibodies against the peroxisomal Deg-protease from Arabidopsis (Deg15) identify the watermelo

  20. Arabidopsis CDS blastp result: AK242585 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK242585 J090010M20 At3g03050.1 68416.m00301 cellulose synthase family protein (CslD3) similar to cellulose... synthase catalytic subunit gi:2827143 from [Arabidopsis thaliana], cellulose syntha

  1. Arabidopsis CDS blastp result: AK242601 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK242601 J090014G03 At3g03050.1 68416.m00301 cellulose synthase family protein (CslD3) similar to cellulose... synthase catalytic subunit gi:2827143 from [Arabidopsis thaliana], cellulose syntha

  2. Arabidopsis CDS blastp result: AK110467 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK110467 002-166-G08 At3g03050.1 cellulose synthase family protein (CslD3) similar to cellulose... synthase catalytic subunit gi:2827143 from [Arabidopsis thaliana], cellulose synthase-7 (gi:962

  3. Arabidopsis CDS blastp result: AK066835 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK066835 J013087I16 At5g16910.1 cellulose synthase family protein similar to gi:2827143 cellulose... synthase catalytic subunit, Arabidopsis thaliana, gi:9622886 cellulose synthase-7 from Zea mays 1e-171 ...

  4. Arabidopsis CDS blastp result: AK102695 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK102695 J033103F21 At5g16910.1 cellulose synthase family protein similar to gi:2827143 cellulose... synthase catalytic subunit, Arabidopsis thaliana, gi:9622886 cellulose synthase-7 from Zea mays 0.0 ...

  5. Arabidopsis CDS blastp result: AK242890 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK242890 J090079L19 At3g03050.1 68416.m00301 cellulose synthase family protein (CslD3) similar to cellulose... synthase catalytic subunit gi:2827143 from [Arabidopsis thaliana], cellulose syntha

  6. Arabidopsis CDS blastp result: AK100523 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK100523 J023100P04 At5g16910.1 cellulose synthase family protein similar to gi:2827143 cellulose... synthase catalytic subunit, Arabidopsis thaliana, gi:9622886 cellulose synthase-7 from Zea mays 0.0 ...

  7. Arabidopsis CDS blastp result: AK065259 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK065259 J013002J18 At5g16910.1 cellulose synthase family protein similar to gi:2827143 cellulose... synthase catalytic subunit, Arabidopsis thaliana, gi:9622886 cellulose synthase-7 from Zea mays 0.0 ...

  8. Arabidopsis CDS blastp result: AK102134 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK102134 J033085F12 At5g16910.1 cellulose synthase family protein similar to gi:2827143 cellulose... synthase catalytic subunit, Arabidopsis thaliana, gi:9622886 cellulose synthase-7 from Zea mays 0.0 ...

  9. The fifth international conference on Arabidopsis research

    Energy Technology Data Exchange (ETDEWEB)

    Hangarter, R.; Scholl, R.; Davis, K.; Feldmann, K.

    1993-12-31

    This volume contains abstracts of oral and poster presentations made in conjunction with the Fifth International Conference on Arabidopsis Research held August 19--22, 1993 at the Ohio State University, Columbus, Ohio.

  10. Autoimmunity in Arabidopsis acd11 Is Mediated by Epigenetic Regulation of an Immune Receptor

    DEFF Research Database (Denmark)

    Palma, K.; Thorgrimsen, S.; Malinovsky, F.G.

    2010-01-01

    Certain pathogens deliver effectors into plant cells to modify host protein targets and thereby suppress immunity. These target modifications can be detected by intracellular immune receptors, or Resistance (R) proteins, that trigger strong immune responses including localized host cell death....... The accelerated cell death 11 (acd11) "lesion mimic" mutant of Arabidopsis thaliana exhibits autoimmune phenotypes such as constitutive defense responses and cell death without pathogen perception. ACD11 encodes a putative sphingosine transfer protein, but its precise role during these processes is unknown......, and that cell death in other lesion mimic mutants may also be caused by inappropriate activation of R genes. Moreover, SDG8 is required for basal and R protein-mediated pathogen resistance in Arabidopsis, revealing the importance of chromatin remodeling as a key process in plant innate immunity....

  11. A Lipid Transfer Protein Increases the Glutathione Content and Enhances Arabidopsis Resistance to a Trichothecene Mycotoxin.

    Directory of Open Access Journals (Sweden)

    John E McLaughlin

    Full Text Available Fusarium head blight (FHB or scab is one of the most important plant diseases worldwide, affecting wheat, barley and other small grains. Trichothecene mycotoxins such as deoxynivalenol (DON accumulate in the grain, presenting a food safety risk and health hazard to humans and animals. Despite considerable breeding efforts, highly resistant wheat or barley cultivars are not available. We screened an activation tagged Arabidopsis thaliana population for resistance to trichothecin (Tcin, a type B trichothecene in the same class as DON. Here we show that one of the resistant lines identified, trichothecene resistant 1 (trr1 contains a T-DNA insertion upstream of two nonspecific lipid transfer protein (nsLTP genes, AtLTP4.4 and AtLTP4.5. Expression of both nsLTP genes was induced in trr1 over 10-fold relative to wild type. Overexpression of AtLTP4.4 provided greater resistance to Tcin than AtLTP4.5 in Arabidopsis thaliana and in Saccharomyces cerevisiae relative to wild type or vector transformed lines, suggesting a conserved protection mechanism. Tcin treatment increased reactive oxygen species (ROS production in Arabidopsis and ROS stain was associated with the chloroplast, the cell wall and the apoplast. ROS levels were attenuated in Arabidopsis and in yeast overexpressing AtLTP4.4 relative to the controls. Exogenous addition of glutathione and other antioxidants enhanced resistance of Arabidopsis to Tcin while the addition of buthionine sulfoximine, an inhibitor of glutathione synthesis, increased sensitivity, suggesting that resistance was mediated by glutathione. Total glutathione content was significantly higher in Arabidopsis and in yeast overexpressing AtLTP4.4 relative to the controls, highlighting the importance of AtLTP4.4 in maintaining the redox state. These results demonstrate that trichothecenes cause ROS accumulation and overexpression of AtLTP4.4 protects against trichothecene-induced oxidative stress by increasing the glutathione

  12. Gibberellic Acid-Stimulated Arabidopsis6 Serves as an Integrator of Gibberellin, Abscisic Acid, and Glucose Signaling during Seed Germination in Arabidopsis.

    Science.gov (United States)

    Zhong, Chunmei; Xu, Hao; Ye, Siting; Wang, Shiyi; Li, Lingfei; Zhang, Shengchun; Wang, Xiaojing

    2015-11-01

    The DELLA protein REPRESSOR OF ga1-3-LIKE2 (RGL2) plays an important role in seed germination under different conditions through a number of transcription factors. However, the functions of the structural genes associated with RGL2-regulated germination are less defined. Here, we report the role of an Arabidopsis (Arabidopsis thaliana) cell wall-localized protein, Gibberellic Acid-Stimulated Arabidopsis6 (AtGASA6), in functionally linking RGL2 and a cell wall loosening expansin protein (Arabidopsis expansin A1 [AtEXPA1]), resulting in the control of embryonic axis elongation and seed germination. AtGASA6-overexpressing seeds showed precocious germination, whereas transfer DNA and RNA interference mutant seeds displayed delayed seed germination under abscisic acid, paclobutrazol, and glucose (Glc) stress conditions. The differences in germination rates resulted from corresponding variation in cell elongation in the hypocotyl-radicle transition region of the embryonic axis. AtGASA6 was down-regulated by RGL2, GLUCOSE INSENSITIVE2, and ABSCISIC ACID-INSENSITIVE5 genes, and loss of AtGASA6 expression in the gasa6 mutant reversed the insensitivity shown by the rgl2 mutant to paclobutrazol and the gin2 mutant to Glc-induced stress, suggesting that it is involved in regulating both the gibberellin and Glc signaling pathways. Furthermore, it was found that the promotion of seed germination and length of embryonic axis by AtGASA6 resulted from a promotion of cell elongation at the embryonic axis mediated by AtEXPA1. Taken together, the data indicate that AtGASA6 links RGL2 and AtEXPA1 functions and plays a role as an integrator of gibberellin, abscisic acid, and Glc signaling, resulting in the regulation of seed germination through a promotion of cell elongation. © 2015 American Society of Plant Biologists. All Rights Reserved.

  13. Hybrid mimics and hybrid vigor in Arabidopsis

    Science.gov (United States)

    Wang, Li; Greaves, Ian K.; Groszmann, Michael; Wu, Li Min; Dennis, Elizabeth S.; Peacock, W. James

    2015-01-01

    F1 hybrids can outperform their parents in yield and vegetative biomass, features of hybrid vigor that form the basis of the hybrid seed industry. The yield advantage of the F1 is lost in the F2 and subsequent generations. In Arabidopsis, from F2 plants that have a F1-like phenotype, we have by recurrent selection produced pure breeding F5/F6 lines, hybrid mimics, in which the characteristics of the F1 hybrid are stabilized. These hybrid mimic lines, like the F1 hybrid, have larger leaves than the parent plant, and the leaves have increased photosynthetic cell numbers, and in some lines, increased size of cells, suggesting an increased supply of photosynthate. A comparison of the differentially expressed genes in the F1 hybrid with those of eight hybrid mimic lines identified metabolic pathways altered in both; these pathways include down-regulation of defense response pathways and altered abiotic response pathways. F6 hybrid mimic lines are mostly homozygous at each locus in the genome and yet retain the large F1-like phenotype. Many alleles in the F6 plants, when they are homozygous, have expression levels different to the level in the parent. We consider this altered expression to be a consequence of transregulation of genes from one parent by genes from the other parent. Transregulation could also arise from epigenetic modifications in the F1. The pure breeding hybrid mimics have been valuable in probing the mechanisms of hybrid vigor and may also prove to be useful hybrid vigor equivalents in agriculture. PMID:26283378

  14. The RNA-binding protein repertoire of Arabidopsis thaliana

    KAUST Repository

    Marondedze, Claudius

    2016-07-11

    RNA-binding proteins (RBPs) have essential roles in determining the fate of RNA from synthesis to decay and have been studied on a protein-by-protein basis, or computationally based on a number of well-characterised RNA-binding domains. Recently, high-throughput methods enabled the capture of mammalian RNA-binding proteomes. To gain insight into the role of Arabidopsis thaliana RBPs at the systems level, we have employed interactome capture techniques using cells from different ecotypes grown in cultures and leaves. In vivo UV-crosslinking of RNA to RBPs, oligo(dT) capture and mass spectrometry yielded 1,145 different proteins including 550 RBPs that either belong to the functional category ‘RNA-binding’, have known RNA-binding domains or have orthologs identified in mammals, C. elegans, or S. cerevisiae in addition to 595 novel candidate RBPs. We noted specific subsets of RBPs in cultured cells and leaves and a comparison of Arabidopsis, mammalian, C. elegans, and S. cerevisiae RBPs reveals a common set of proteins with a role in intermediate metabolism, as well as distinct differences suggesting that RBPs are also species and tissue specific. This study provides a foundation for studies that will advance our understanding of the biological significance of RBPs in plant developmental and stimulus specific responses.

  15. Heterologous Reconstitution of Omega-3 Polyunsaturated Fatty Acids in Arabidopsis

    Directory of Open Access Journals (Sweden)

    Sun Hee Kim

    2015-01-01

    Full Text Available Reconstitution of nonnative, very-long-chain polyunsaturated fatty acid (VLC-PUFA biosynthetic pathways in Arabidopsis thaliana was undertaken. The introduction of three primary biosynthetic activities to cells requires the stable coexpression of multiple proteins within the same cell. Herein, we report that C22 VLC-PUFAs were synthesized from C18 precursors by reactions catalyzed by Δ6-desaturase, an ELOVL5-like enzyme involved in VLC-PUFA elongation, and Δ5-desaturase. Coexpression of the corresponding genes (McD6DES, AsELOVL5, and PtD5DES under the control of the seed-specific vicilin promoter resulted in production of docosapentaenoic acid (22:5 n-3 and docosatetraenoic acid (22:4 n-6 as well as eicosapentaenoic acid (20:5 n-3 and arachidonic acid (20:4 n-6 in Arabidopsis seeds. The contributions of the transgenic enzymes and endogenous fatty acid metabolism were determined. Specifically, the reasonable synthesis of omega-3 stearidonic acid (18:4 n-3 could be a useful tool to obtain a sustainable system for the production of omega-3 fatty acids in seeds of a transgenic T3 line 63-1. The results indicated that coexpression of the three proteins was stable. Therefore, this study suggests that metabolic engineering of oilseed crops to produce VLC-PUFAs is feasible.

  16. Mining the active proteome of Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Renier A. L. Van Der Hoorn

    2011-11-01

    Full Text Available Assigning functions to the >30.000 proteins encoded by the Arabidopsis genome is a challenging task of the Arabidopsis Functional Genomics Network. Although genome-wide technologies like proteomics and transcriptomics have generated a wealth of information that significantly accelerated gene annotation, protein activities are poorly predicted by transcript or protein levels as protein activities are post-translationally regulated. To directly display protein activities in Arabidopsis proteomes, we developed and applied Activity-based Protein Profiling (ABPP. ABPP is based on the use of small molecule probes that react with the catalytic residues of distinct protein classes in an activity-dependent manner. Labeled proteins are separated and detected from proteins gels and purified and identified by mass spectrometry. Using probes of six different chemotypes we have displayed of activities of 76 Arabidopsis proteins. These proteins represent over ten different protein classes that contain over 250 Arabidopsis proteins, including cysteine- serine- and metallo-proteases, lipases, acyltransferases, and the proteasome. We have developed methods for identification of in vivo labeled proteins using click-chemistry and for in vivo imaging with fluorescent probes. In vivo labeling has revealed novel protein activities and unexpected subcellular activities of the proteasome. Labeling of extracts displayed several differential activities e.g. of the proteasome during immune response and methylesterases during infection. These studies illustrate the power of ABPP to display the functional proteome and testify to a successful interdisciplinary collaboration involving chemical biology, organic chemistry and proteomics.

  17. Bioavailability of nanoparticulate hematite to Arabidopsis thaliana

    International Nuclear Information System (INIS)

    Marusenko, Yevgeniy; Shipp, Jessie; Hamilton, George A.; Morgan, Jennifer L.L.; Keebaugh, Michael; Hill, Hansina; Dutta, Arnab; Zhuo, Xiaoding; Upadhyay, Nabin; Hutchings, James; Herckes, Pierre; Anbar, Ariel D.; Shock, Everett; Hartnett, Hilairy E.

    2013-01-01

    The environmental effects and bioavailability of nanoparticulate iron (Fe) to plants are currently unknown. Here, plant bioavailability of synthesized hematite Fe nanoparticles was evaluated using Arabidopsis thaliana (A. thaliana) as a model. Over 56-days of growing wild-type A. thaliana, the nanoparticle-Fe and no-Fe treatments had lower plant biomass, lower chlorophyll concentrations, and lower internal Fe concentrations than the Fe-treatment. Results for the no-Fe and nanoparticle-Fe treatments were consistently similar throughout the experiment. These results suggest that nanoparticles (mean diameter 40.9 nm, range 22.3–67.0 nm) were not taken up and therefore not bioavailable to A. thaliana. Over 14-days growing wild-type and transgenic (Type I/II proton pump overexpression) A. thaliana, the Type I plant grew more than the wild-type in the nanoparticle-Fe treatment, suggesting Type I plants cope better with Fe limitation; however, the nanoparticle-Fe and no-Fe treatments had similar growth for all plant types. -- Highlights: ► Iron nanoparticles were synthesized and assessed for bioavailability to Arabidopsis. ► Arabidopsis grew better in the presence of EDTA-bound iron than nanoparticulate iron. ► Arabidopsis grew the same in the presence of nanoparticulate iron compared to no iron. -- Synthesized iron nanoparticles were not bioavailable to Arabidopsis thaliana in agar nutrient media

  18. Induction of Systemic Resistance against Aphids by Endophytic Bacillus velezensis YC7010 via Expressing PHYTOALEXIN DEFICIENT4 in Arabidopsis.

    Science.gov (United States)

    Rashid, Md Harun-Or-; Khan, Ajmal; Hossain, Mohammad T; Chung, Young R

    2017-01-01

    Aphids are the most destructive insect pests. They suck the sap and transmit plant viruses, causing widespread yield loss of many crops. A multifunctional endophytic bacterial strain Bacillus velezensis YC7010 has been found to induce systemic resistance against bacterial and fungal pathogens of rice. However, its activity against insects attack and underlying cellular and molecular defense mechanisms are not elucidated yet. Here, we show that root drenching of Arabidopsis seedlings with B. velezensis YC7010 can induce systemic resistance against green peach aphid (GPA), Myzus persicae . Treatment of bacterial suspension of B. velezensis YC7010 at 2 × 10 7 CFU/ml to Arabidopsis rhizosphere induced higher accumulation of hydrogen peroxide, cell death, and callose deposition in leaves compared to untreated plants at 6 days after infestation of GPA. Salicylic acid, jasmonic acid, ethylene, and abscisic acid were not required to confer defense against GPA in Arabidopsis plants treated by B. velezensis YC7010. Bacterial treatment with B. velezensis YC7010 significantly reduced settling, feeding and reproduction of GPA on Arabidopsis leaves via strongly expressing senescence-promoting gene PHYTOALEXIN DEFICIENT4 ( PAD4 ) while suppressing BOTRYTIS-INDUCED KINASE1 ( BIK1 ). These results indicate that B. velezensis YC7010-induced systemic resistance to the GPA is a hypersensitive response mainly dependent on higher expression of PAD4 with suppression of BIK1 , resulting in more accumulation of hydrogen peroxide, cell death, and callose deposition in Arabidopsis .

  19. Induction of Systemic Resistance against Aphids by Endophytic Bacillus velezensis YC7010 via Expressing PHYTOALEXIN DEFICIENT4 in Arabidopsis

    Science.gov (United States)

    Rashid, Md. Harun-Or-; Khan, Ajmal; Hossain, Mohammad T.; Chung, Young R.

    2017-01-01

    Aphids are the most destructive insect pests. They suck the sap and transmit plant viruses, causing widespread yield loss of many crops. A multifunctional endophytic bacterial strain Bacillus velezensis YC7010 has been found to induce systemic resistance against bacterial and fungal pathogens of rice. However, its activity against insects attack and underlying cellular and molecular defense mechanisms are not elucidated yet. Here, we show that root drenching of Arabidopsis seedlings with B. velezensis YC7010 can induce systemic resistance against green peach aphid (GPA), Myzus persicae. Treatment of bacterial suspension of B. velezensis YC7010 at 2 × 107 CFU/ml to Arabidopsis rhizosphere induced higher accumulation of hydrogen peroxide, cell death, and callose deposition in leaves compared to untreated plants at 6 days after infestation of GPA. Salicylic acid, jasmonic acid, ethylene, and abscisic acid were not required to confer defense against GPA in Arabidopsis plants treated by B. velezensis YC7010. Bacterial treatment with B. velezensis YC7010 significantly reduced settling, feeding and reproduction of GPA on Arabidopsis leaves via strongly expressing senescence-promoting gene PHYTOALEXIN DEFICIENT4 (PAD4) while suppressing BOTRYTIS-INDUCED KINASE1 (BIK1). These results indicate that B. velezensis YC7010-induced systemic resistance to the GPA is a hypersensitive response mainly dependent on higher expression of PAD4 with suppression of BIK1, resulting in more accumulation of hydrogen peroxide, cell death, and callose deposition in Arabidopsis. PMID:28261260

  20. Comparative interactomics: analysis of arabidopsis 14-3-3 complexes reveals highly conserved 14-3-3 interactions between humans and plants.

    Science.gov (United States)

    Paul, Anna-Lisa; Liu, Li; McClung, Scott; Laughner, Beth; Chen, Sixue; Ferl, Robert J

    2009-04-01

    As a first step in the broad characterization of plant 14-3-3 multiprotein complexes in vivo, stringent and specific antibody affinity purification was used to capture 14-3-3s together with their interacting proteins from extracts of Arabidopsis cell suspension cultures. Approximately 120 proteins were identified as potential in vivo 14-3-3 interacting proteins by mass spectrometry of the recovered complexes. Comparison of the proteins in this data set with the 14-3-3 interacting proteins from a similar study in human embryonic kidney cell cultures revealed eight interacting proteins that likely represent reasonably abundant, fundamental 14-3-3 interaction complexes that are highly conserved across all eukaryotes. The Arabidopsis 14-3-3 interaction data set was also compared to a yeast in vivo 14-3-3 interaction data set. Four 14-3-3 interacting proteins are conserved in yeast, humans, and Arabidopsis. Comparisons of the data sets based on biochemical function revealed many additional similarities in the human and Arabidopsis data sets that represent conserved functional interactions, while also leaving many proteins uniquely identified in either Arabidopsis or human cells. In particular, the Arabidopsis interaction data set is enriched for proteins involved in metabolism.

  1. The arabidopsis cyclic nucleotide interactome

    KAUST Repository

    Donaldson, Lara Elizabeth

    2016-05-11

    Background Cyclic nucleotides have been shown to play important signaling roles in many physiological processes in plants including photosynthesis and defence. Despite this, little is known about cyclic nucleotide-dependent signaling mechanisms in plants since the downstream target proteins remain unknown. This is largely due to the fact that bioinformatics searches fail to identify plant homologs of protein kinases and phosphodiesterases that are the main targets of cyclic nucleotides in animals. Methods An affinity purification technique was used to identify cyclic nucleotide binding proteins in Arabidopsis thaliana. The identified proteins were subjected to a computational analysis that included a sequence, transcriptional co-expression and functional annotation analysis in order to assess their potential role in plant cyclic nucleotide signaling. Results A total of twelve cyclic nucleotide binding proteins were identified experimentally including key enzymes in the Calvin cycle and photorespiration pathway. Importantly, eight of the twelve proteins were shown to contain putative cyclic nucleotide binding domains. Moreover, the identified proteins are post-translationally modified by nitric oxide, transcriptionally co-expressed and annotated to function in hydrogen peroxide signaling and the defence response. The activity of one of these proteins, GLYGOLATE OXIDASE 1, a photorespiratory enzyme that produces hydrogen peroxide in response to Pseudomonas, was shown to be repressed by a combination of cGMP and nitric oxide treatment. Conclusions We propose that the identified proteins function together as points of cross-talk between cyclic nucleotide, nitric oxide and reactive oxygen species signaling during the defence response.

  2. GLABROUS INFLORESCENCE STEMS (GIS) is required for trichome branching through gibberellic acid signaling in Arabidopsis.

    Science.gov (United States)

    An, Lijun; Zhou, Zhongjing; Su, Sha; Yan, An; Gan, Yinbo

    2012-02-01

    Cell differentiation generally corresponds to the cell cycle, typically forming a non-dividing cell with a unique differentiated morphology, and Arabidopsis trichome is an excellent model system to study all aspects of cell differentiation. Although gibberellic acid is reported to be involved in trichome branching in Arabidopsis, the mechanism for such signaling is unclear. Here, we demonstrated that GLABROUS INFLORESCENCE STEMS (GIS) is required for the control of trichome branching through gibberellic acid signaling. The phenotypes of a loss-of-function gis mutant and an overexpressor showed that GIS acted as a repressor to control trichome branching. Our results also show that GIS is not required for cell endoreduplication, and our molecular and genetic study results have shown that GIS functions downstream of the key regulator of trichome branching, STICHEL (STI), to control trichome branching through the endoreduplication-independent pathway. Furthermore, our results also suggest that GIS controls trichome branching in Arabidopsis through two different pathways and acts either upstream or downstream of the negative regulator of gibbellic acid signaling SPINDLY (SPY).

  3. Glufosinate ammonium selection of transformed Arabidopsis.

    Science.gov (United States)

    Weigel, Detlef; Glazebrook, Jane

    2006-12-01

    INTRODUCTIONOne of the most commonly used markers for the selection of transgenic Arabidopsis is resistance to glufosinate ammonium, an herbicide that is sold under a variety of trade names including Basta and Finale. Resistance to glufosinate ammonium is conferred by the bacterial bialophos resistance gene (BAR) encoding the enzyme phosphinotricin acetyl transferase (PAT). This protocol describes the use of glufosinate ammonium to select transformed Arabidopsis plants. The major advantage of glufosinate ammonium selection is that it can be performed on plants growing in soil and does not require the use of sterile techniques.

  4. Interactions between co-expressed Arabidopsis sucrose transporters in the split-ubiquitin system

    Directory of Open Access Journals (Sweden)

    Lalonde Sylvie

    2003-03-01

    Full Text Available Abstract Background The Arabidopsis genome contains nine sucrose transporter paralogs falling into three clades: SUT1-like, SUT2 and SUT4. The carriers differ in their kinetic properties. Many transport proteins are known to exist as oligomers. The yeast-based split ubiquitin system can be used to analyze the ability of membrane proteins to interact. Results Promoter-GUS fusions were used to analyze the cellular expression of the three transporter genes in transgenic Arabidopsis plants. All three fusion genes are co-expressed in companion cells. Protein-protein interactions between Arabidopsis sucrose transporters were tested using the split ubiquitin system. Three paralogous sucrose transporters are capable of interacting as either homo- or heteromers. The interactions are specific, since a potassium channel and a glucose transporter did not show interaction with sucrose transporters. Also the biosynthetic and metabolizing enzymes, sucrose phosphate phosphatase and sucrose synthase, which were found to be at least in part bound to the plasma membrane, did not specifically interact with sucrose transporters. Conclusions The split-ubiquitin system provides a powerful tool to detect potential interactions between plant membrane proteins by heterologous expression in yeast, and can be used to screen for interactions with membrane proteins as baits. Like other membrane proteins, the Arabidopsis sucrose transporters are able to form oligomers. The biochemical approaches are required to confirm the in planta interaction.

  5. Wheat TaSP gene improves salt tolerance in transgenic Arabidopsis thaliana.

    Science.gov (United States)

    Ma, Xiaoli; Cui, Weina; Liang, Wenji; Huang, Zhanjing

    2015-12-01

    A novel salt-induced gene with unknown functions was cloned through analysis of gene expression profile of a salt-tolerant wheat mutant RH8706-49 under salt stress. The gene was named Triticum aestivum salt-related protein (TaSP) and deposited in GenBank (Accession No. KF307326). Quantitative polymerase chain reaction (qPCR) results showed that TaSP expression was induced under salt, abscisic acid (ABA), and polyethylene glycol (PEG) stresses. Subcellular localization revealed that TaSP was mainly localized in cell membrane. Overexpression of TaSP in Arabidopsis could improve salt tolerance of 35S::TaSP transgenic Arabidopsis. 35S::TaSP transgenic Arabidopsis lines after salt stress presented better physiological indexes than the control group. In the non-invasive micro-test (NMT), an evident Na(+) excretion was observed at the root tip of salt-stressed 35S::TaSP transgenic Arabidopsis. TaSP promoter was cloned, and its beta-glucuronidase (GUS) activities before and after ABA, salt, cold, heat, and salicylic acid (SA) stresses were determined. Full-length TaSP promoter contained ABA and salt response elements. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  6. GDP-D-mannose epimerase regulates male gametophyte development, plant growth and leaf senescence in Arabidopsis.

    Science.gov (United States)

    Qi, Tiancong; Liu, Zhipeng; Fan, Meng; Chen, Yan; Tian, Haixia; Wu, Dewei; Gao, Hua; Ren, Chunmei; Song, Susheng; Xie, Daoxin

    2017-09-04

    Plant GDP-D-mannose epimerase (GME) converts GDP-D-mannose to GDP-L-galactose, a precursor of both L-ascorbate (vitamin C) and cell wall polysaccharides. However, the genetic functions of GME in Arabidopsis are unclear. In this study, we found that mutations in Arabidopsis GME affect pollen germination, pollen tube elongation, and transmission and development of the male gametophyte through analysis of the heterozygous GME/gme plants and the homozygous gme plants. Arabidopsis gme mutants also exhibit severe growth defects and early leaf senescence. Surprisingly, the defects in male gametophyte in the gme plants are not restored by L-ascorbate, boric acid or GDP-L-galactose, though boric acid rescues the growth defects of the mutants, indicating that GME may regulate male gametophyte development independent of L-ascorbate and GDP-L-galactose. These results reveal key roles for Arabidopsis GME in reproductive development, vegetative growth and leaf senescence, and suggest that GME regulates plant growth and controls male gametophyte development in different manners.

  7. Arsenic triggers the nitric oxide (NO) and S-nitrosoglutathione (GSNO) metabolism in Arabidopsis

    International Nuclear Information System (INIS)

    Leterrier, Marina; Airaki, Morad; Palma, José M.; Chaki, Mounira; Barroso, Juan B.; Corpas, Francisco J.

    2012-01-01

    Environmental contamination by arsenic constitutes a problem in many countries, and its accumulation in food crops may pose health complications for humans. Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are involved at various levels in the mechanism of responding to environmental stress in higher plants. Using Arabidopsis seedlings exposed to different arsenate concentrations, physiological and biochemical parameters were analyzed to determine the status of ROS and RNS metabolisms. Arsenate provoked a significant reduction in growth parameters and an increase in lipid oxidation. These changes were accompanied by an alteration in antioxidative enzymes and the nitric oxide (NO) metabolism, with a significant increase in NO content, S-nitrosoglutathione reductase (GSNOR) activity and protein tyrosine nitration as well as a concomitant reduction in glutathione and S-nitrosoglutathione (GSNO) content. Our results indicate that 500 μM arsenate (AsV) causes nitro-oxidative stress in Arabidopsis, being the glutathione reductase and the GSNOR activities clearly affected. - Highlights: ► In Arabidopsis, arsenate provokes damages in the membrane integrity of root cells. ► As induces an oxidative stress according to an increase in lipid oxidation. ► NO content and protein tyrosine nitration increases under arsenate stress. ► Arsenate provokes a reduction of GSH, GSSG and GSNO content. ► Arsenate induces a nitro-oxidative stress in Arabidopsis. - Arsenic stress affects nitric oxide (NO) and glutathione (GSH) metabolism which provokes a nitro-oxidative stress.

  8. Wheat Transcription Factor TaAREB3 Participates in Drought and Freezing Tolerances in Arabidopsis.

    Science.gov (United States)

    Wang, Jingyi; Li, Qian; Mao, Xinguo; Li, Ang; Jing, Ruilian

    2016-01-01

    AREB (ABA response element binding) proteins in plants play direct regulatory roles in response to multiple stresses, but their functions in wheat (Triticum aestivum L.) are not clear. In the present study, TaAREB3, a new member of the AREB transcription factor family, was isolated from wheat. Sequence analysis showed that the TaAREB3 protein is composed of three parts, a conserved N-terminal, a variable M region, and a conserved C-terminal with a bZIP domain. It belongs to the group A subfamily of bZIP transcription factors. TaAREB3 was constitutively expressed in stems, leaves, florets, anthers, pistils, seeds, and most highly, in roots. TaAREB3 gene expression was induced with abscisic acid (ABA) and low temperature stress, and its protein was localized in the nucleus when transiently expressed in tobacco epidermal cells and stably expressed in transgenic Arabidopsis. TaAREB3 protein has transcriptional activation activity, and can bind to the ABRE cis-element in vitro. Overexpression of TaAREB3 in Arabidopsis not only enhanced ABA sensitivity, but also strengthened drought and freezing tolerances. TaAREB3 also activated RD29A, RD29B, COR15A, and COR47 by binding to their promoter regions in transgenic Arabidopsis. These results demonstrated that TaAREB3 plays an important role in drought and freezing tolerances in Arabidopsis.

  9. Novel disease susceptibility factors for fungal necrotrophic pathogens in Arabidopsis.

    Science.gov (United States)

    Dobón, Albor; Canet, Juan Vicente; García-Andrade, Javier; Angulo, Carlos; Neumetzler, Lutz; Persson, Staffan; Vera, Pablo

    2015-04-01

    Host cells use an intricate signaling system to respond to invasions by pathogenic microorganisms. Although several signaling components of disease resistance against necrotrophic fungal pathogens have been identified, our understanding for how molecular components and host processes contribute to plant disease susceptibility is rather sparse. Here, we identified four transcription factors (TFs) from Arabidopsis that limit pathogen spread. Arabidopsis mutants defective in any of these TFs displayed increased disease susceptibility to Botrytis cinerea and Plectosphaerella cucumerina, and a general activation of non-immune host processes that contribute to plant disease susceptibility. Transcriptome analyses revealed that the mutants share a common transcriptional signature of 77 up-regulated genes. We characterized several of the up-regulated genes that encode peptides with a secretion signal, which we named PROVIR (for provirulence) factors. Forward and reverse genetic analyses revealed that many of the PROVIRs are important for disease susceptibility of the host to fungal necrotrophs. The TFs and PROVIRs identified in our work thus represent novel genetic determinants for plant disease susceptibility to necrotrophic fungal pathogens.

  10. Flavonoid accumulation patterns of transparent testa mutants of arabidopsis

    Science.gov (United States)

    Peer, W. A.; Brown, D. E.; Tague, B. W.; Muday, G. K.; Taiz, L.; Murphy, A. S.

    2001-01-01

    Flavonoids have been implicated in the regulation of auxin movements in Arabidopsis. To understand when and where flavonoids may be acting to control auxin movement, the flavonoid accumulation pattern was examined in young seedlings and mature tissues of wild-type Arabidopsis. Using a variety of biochemical and visualization techniques, flavonoid accumulation in mature plants was localized in cauline leaves, pollen, stigmata, and floral primordia, and in the stems of young, actively growing inflorescences. In young Landsberg erecta seedlings, aglycone flavonols accumulated developmentally in three regions, the cotyledonary node, the hypocotyl-root transition zone, and the root tip. Aglycone flavonols accumulated at the hypocotyl-root transition zone in a developmental and tissue-specific manner with kaempferol in the epidermis and quercetin in the cortex. Quercetin localized subcellularly in the nuclear region, plasma membrane, and endomembrane system, whereas kaempferol localized in the nuclear region and plasma membrane. The flavonoid accumulation pattern was also examined in transparent testa mutants blocked at different steps in the flavonoid biosynthesis pathway. The transparent testa mutants were shown to have precursor accumulation patterns similar to those of end product flavonoids in wild-type Landsberg erecta, suggesting that synthesis and end product accumulation occur in the same cells.

  11. Novel disease susceptibility factors for fungal necrotrophic pathogens in Arabidopsis.

    Directory of Open Access Journals (Sweden)

    Albor Dobón

    2015-04-01

    Full Text Available Host cells use an intricate signaling system to respond to invasions by pathogenic microorganisms. Although several signaling components of disease resistance against necrotrophic fungal pathogens have been identified, our understanding for how molecular components and host processes contribute to plant disease susceptibility is rather sparse. Here, we identified four transcription factors (TFs from Arabidopsis that limit pathogen spread. Arabidopsis mutants defective in any of these TFs displayed increased disease susceptibility to Botrytis cinerea and Plectosphaerella cucumerina, and a general activation of non-immune host processes that contribute to plant disease susceptibility. Transcriptome analyses revealed that the mutants share a common transcriptional signature of 77 up-regulated genes. We characterized several of the up-regulated genes that encode peptides with a secretion signal, which we named PROVIR (for provirulence factors. Forward and reverse genetic analyses revealed that many of the PROVIRs are important for disease susceptibility of the host to fungal necrotrophs. The TFs and PROVIRs identified in our work thus represent novel genetic determinants for plant disease susceptibility to necrotrophic fungal pathogens.

  12. The MADS Box Genes ABS, SHP1, and SHP2 Are Essential for the Coordination of Cell Divisions in Ovule and Seed Coat Development and for Endosperm Formation in Arabidopsis thaliana.

    Science.gov (United States)

    Ehlers, Katrin; Bhide, Amey S; Tekleyohans, Dawit G; Wittkop, Benjamin; Snowdon, Rod J; Becker, Annette

    2016-01-01

    Seed formation is a pivotal process in plant reproduction and dispersal. It begins with megagametophyte development in the ovule, followed by fertilization and subsequently coordinated development of embryo, endosperm, and maternal seed coat. Two closely related MADS-box genes, SHATTERPROOF 1 and 2 (SHP1 and SHP2) are involved in specifying ovule integument identity in Arabidopsis thaliana. The MADS box gene ARABIDOPSIS BSISTER (ABS or TT16) is required, together with SEEDSTICK (STK) for the formation of endothelium, part of the seed coat and innermost tissue layer formed by the maternal plant. Little is known about the genetic interaction of SHP1 and SHP2 with ABS and the coordination of endosperm and seed coat development. In this work, mutant and expression analysis shed light on this aspect of concerted development. Triple tt16 shp1 shp2 mutants produce malformed seedlings, seed coat formation defects, fewer seeds, and mucilage reduction. While shp1 shp2 mutants fail to coordinate the timely development of ovules, tt16 mutants show less peripheral endosperm after fertilization. Failure in coordinated division of the innermost integument layer in early ovule stages leads to inner seed coat defects in tt16 and tt16 shp1 shp2 triple mutant seeds. An antagonistic action of ABS and SHP1/SHP2 is observed in inner seed coat layer formation. Expression analysis also indicates that ABS represses SHP1, SHP2, and FRUITFUL expression. Our work shows that the evolutionary conserved Bsister genes are required not only for endothelium but also for endosperm development and genetically interact with SHP1 and SHP2 in a partially antagonistic manner.

  13. The MADS Box Genes ABS, SHP1, and SHP2 Are Essential for the Coordination of Cell Divisions in Ovule and Seed Coat Development and for Endosperm Formation in Arabidopsis thaliana.

    Directory of Open Access Journals (Sweden)

    Katrin Ehlers

    Full Text Available Seed formation is a pivotal process in plant reproduction and dispersal. It begins with megagametophyte development in the ovule, followed by fertilization and subsequently coordinated development of embryo, endosperm, and maternal seed coat. Two closely related MADS-box genes, SHATTERPROOF 1 and 2 (SHP1 and SHP2 are involved in specifying ovule integument identity in Arabidopsis thaliana. The MADS box gene ARABIDOPSIS BSISTER (ABS or TT16 is required, together with SEEDSTICK (STK for the formation of endothelium, part of the seed coat and innermost tissue layer formed by the maternal plant. Little is known about the genetic interaction of SHP1 and SHP2 with ABS and the coordination of endosperm and seed coat development. In this work, mutant and expression analysis shed light on this aspect of concerted development. Triple tt16 shp1 shp2 mutants produce malformed seedlings, seed coat formation defects, fewer seeds, and mucilage reduction. While shp1 shp2 mutants fail to coordinate the timely development of ovules, tt16 mutants show less peripheral endosperm after fertilization. Failure in coordinated division of the innermost integument layer in early ovule stages leads to inner seed coat defects in tt16 and tt16 shp1 shp2 triple mutant seeds. An antagonistic action of ABS and SHP1/SHP2 is observed in inner seed coat layer formation. Expression analysis also indicates that ABS represses SHP1, SHP2, and FRUITFUL expression. Our work shows that the evolutionary conserved Bsister genes are required not only for endothelium but also for endosperm development and genetically interact with SHP1 and SHP2 in a partially antagonistic manner.

  14. Revealing structure and assembly cues for Arabidopsis root-inhabiting bacterial microbiota.

    Science.gov (United States)

    Bulgarelli, Davide; Rott, Matthias; Schlaeppi, Klaus; Ver Loren van Themaat, Emiel; Ahmadinejad, Nahal; Assenza, Federica; Rauf, Philipp; Huettel, Bruno; Reinhardt, Richard; Schmelzer, Elmon; Peplies, Joerg; Gloeckner, Frank Oliver; Amann, Rudolf; Eickhorst, Thilo; Schulze-Lefert, Paul

    2012-08-02

    The plant root defines the interface between a multicellular eukaryote and soil, one of the richest microbial ecosystems on Earth. Notably, soil bacteria are able to multiply inside roots as benign endophytes and modulate plant growth and development, with implications ranging from enhanced crop productivity to phytoremediation. Endophytic colonization represents an apparent paradox of plant innate immunity because plant cells can detect an array of microbe-associated molecular patterns (also known as MAMPs) to initiate immune responses to terminate microbial multiplication. Several studies attempted to describe the structure of bacterial root endophytes; however, different sampling protocols and low-resolution profiling methods make it difficult to infer general principles. Here we describe methodology to characterize and compare soil- and root-inhabiting bacterial communities, which reveals not only a function for metabolically active plant cells but also for inert cell-wall features in the selection of soil bacteria for host colonization. We show that the roots of Arabidopsis thaliana, grown in different natural soils under controlled environmental conditions, are preferentially colonized by Proteobacteria, Bacteroidetes and Actinobacteria, and each bacterial phylum is represented by a dominating class or family. Soil type defines the composition of root-inhabiting bacterial communities and host genotype determines their ribotype profiles to a limited extent. The identification of soil-type-specific members within the root-inhabiting assemblies supports our conclusion that these represent soil-derived root endophytes. Surprisingly, plant cell-wall features of other tested plant species seem to provide a sufficient cue for the assembly of approximately 40% of the Arabidopsis bacterial root-inhabiting microbiota, with a bias for Betaproteobacteria. Thus, this root sub-community may not be Arabidopsis-specific but saprophytic bacteria that would naturally be found

  15. Expression Profiling during Arabidopsis/Downy Mildew Interaction Reveals a Highly-Expressed Effector That Attenuates Responses to Salicylic Acid

    Science.gov (United States)

    Asai, Shuta; Caillaud, Marie-Cécile; Furzer, Oliver J.; Ishaque, Naveed; Wirthmueller, Lennart; Fabro, Georgina; Shirasu, Ken; Jones, Jonathan D. G.

    2014-01-01

    Plants have evolved strong innate immunity mechanisms, but successful pathogens evade or suppress plant immunity via effectors delivered into the plant cell. Hyaloperonospora arabidopsidis (Hpa) causes downy mildew on Arabidopsis thaliana, and a genome sequence is available for isolate Emoy2. Here, we exploit the availability of genome sequences for Hpa and Arabidopsis to measure gene-expression changes in both Hpa and Arabidopsis simultaneously during infection. Using a high-throughput cDNA tag sequencing method, we reveal expression patterns of Hpa predicted effectors and Arabidopsis genes in compatible and incompatible interactions, and promoter elements associated with Hpa genes expressed during infection. By resequencing Hpa isolate Waco9, we found it evades Arabidopsis resistance gene RPP1 through deletion of the cognate recognized effector ATR1. Arabidopsis salicylic acid (SA)-responsive genes including PR1 were activated not only at early time points in the incompatible interaction but also at late time points in the compatible interaction. By histochemical analysis, we found that Hpa suppresses SA-inducible PR1 expression, specifically in the haustoriated cells into which host-translocated effectors are delivered, but not in non-haustoriated adjacent cells. Finally, we found a highly-expressed Hpa effector candidate that suppresses responsiveness to SA. As this approach can be easily applied to host-pathogen interactions for which both host and pathogen genome sequences are available, this work opens the door towards transcriptome studies in infection biology that should help unravel pathogen infection strategies and the mechanisms by which host defense responses are overcome. PMID:25329884

  16. Expression profiling during arabidopsis/downy mildew interaction reveals a highly-expressed effector that attenuates responses to salicylic acid.

    Directory of Open Access Journals (Sweden)

    Shuta Asai

    2014-10-01

    Full Text Available Plants have evolved strong innate immunity mechanisms, but successful pathogens evade or suppress plant immunity via effectors delivered into the plant cell. Hyaloperonospora arabidopsidis (Hpa causes downy mildew on Arabidopsis thaliana, and a genome sequence is available for isolate Emoy2. Here, we exploit the availability of genome sequences for Hpa and Arabidopsis to measure gene-expression changes in both Hpa and Arabidopsis simultaneously during infection. Using a high-throughput cDNA tag sequencing method, we reveal expression patterns of Hpa predicted effectors and Arabidopsis genes in compatible and incompatible interactions, and promoter elements associated with Hpa genes expressed during infection. By resequencing Hpa isolate Waco9, we found it evades Arabidopsis resistance gene RPP1 through deletion of the cognate recognized effector ATR1. Arabidopsis salicylic acid (SA-responsive genes including PR1 were activated not only at early time points in the incompatible interaction but also at late time points in the compatible interaction. By histochemical analysis, we found that Hpa suppresses SA-inducible PR1 expression, specifically in the haustoriated cells into which host-translocated effectors are delivered, but not in non-haustoriated adjacent cells. Finally, we found a highly-expressed Hpa effector candidate that suppresses responsiveness to SA. As this approach can be easily applied to host-pathogen interactions for which both host and pathogen genome sequences are available, this work opens the door towards transcriptome studies in infection biology that should help unravel pathogen infection strategies and the mechanisms by which host defense responses are overcome.

  17. REDUCED CHLOROPLAST COVERAGE genes from Arabidopsis thaliana help to establish the size of the chloroplast compartment.

    Science.gov (United States)

    Larkin, Robert M; Stefano, Giovanni; Ruckle, Michael E; Stavoe, Andrea K; Sinkler, Christopher A; Brandizzi, Federica; Malmstrom, Carolyn M; Osteryoung, Katherine W

    2016-02-23

    Eukaryotic cells require mechanisms to establish the proportion of cellular volume devoted to particular organelles. These mechanisms are poorly understood. From a screen for plastid-to-nucleus signaling mutants in Arabidopsis thaliana, we cloned a mutant allele of a gene that encodes a protein of unknown function that is homologous to two other Arabidopsis genes of unknown function and to FRIENDLY, which was previously shown to promote the normal distribution of mitochondria in Arabidopsis. In contrast to FRIENDLY, these three homologs of FRIENDLY are found only in photosynthetic organisms. Based on these data, we proposed that FRIENDLY expanded into a small gene family to help regulate the energy metabolism of cells that contain both mitochondria and chloroplasts. Indeed, we found that knocking out these genes caused a number of chloroplast phenotypes, including a reduction in the proportion of cellular volume devoted to chloroplasts to 50% of wild type. Thus, we refer to these genes as REDUCED CHLOROPLAST COVERAGE (REC). The size of the chloroplast compartment was reduced most in rec1 mutants. The REC1 protein accumulated in the cytosol and the nucleus. REC1 was excluded from the nucleus when plants were treated with amitrole, which inhibits cell expansion and chloroplast function. We conclude that REC1 is an extraplastidic protein that helps to establish the size of the chloroplast compartment, and that signals derived from cell expansion or chloroplasts may regulate REC1.

  18. 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.

  19. Identification of the Raptor-binding motif on Arabidopsis S6 kinase and its use as a TOR signaling suppressor

    Energy Technology Data Exchange (ETDEWEB)

    Son, Ora; Kim, Sunghan; Hur, Yoon-Sun; Cheon, Choong-Ill, E-mail: ccheon@sookmyung.ac.kr

    2016-03-25

    TOR (target of rapamycin) kinase signaling plays central role as a regulator of growth and proliferation in all eukaryotic cells and its key signaling components and effectors are also conserved in plants. Unlike the mammalian and yeast counterparts, however, we found through yeast two-hybrid analysis that multiple regions of the Arabidopsis Raptor (regulatory associated protein of TOR) are required for binding to its substrate. We also identified that a 44-amino acid region at the N-terminal end of Arabidopsis ribosomal S6 kinase 1 (AtS6K1) specifically interacted with AtRaptor1, indicating that this region may contain a functional equivalent of the TOS (TOR-Signaling) motif present in the mammalian TOR substrates. Transient over-expression of this 44-amino acid fragment in Arabidopsis protoplasts resulted in significant decrease in rDNA transcription, demonstrating a feasibility of developing a new plant-specific TOR signaling inhibitor based upon perturbation of the Raptor-substrate interaction. - Highlights: • Multiple regions on the Arabidopsis Raptor protein were found to be involved in substrate binding. • N-terminal end of the Arabidopsis ribosomal S6 kinase 1 (AtS6K1) was responsible for interacting with AtRaptor1. • The Raptor-interacting fragment of AtS6K1 could be utilized as an effective inhibitor of plant TOR signaling.

  20. Identification of the Raptor-binding motif on Arabidopsis S6 kinase and its use as a TOR signaling suppressor

    International Nuclear Information System (INIS)

    Son, Ora; Kim, Sunghan; Hur, Yoon-Sun; Cheon, Choong-Ill

    2016-01-01

    TOR (target of rapamycin) kinase signaling plays central role as a regulator of growth and proliferation in all eukaryotic cells and its key signaling components and effectors are also conserved in plants. Unlike the mammalian and yeast counterparts, however, we found through yeast two-hybrid analysis that multiple regions of the Arabidopsis Raptor (regulatory associated protein of TOR) are required for binding to its substrate. We also identified that a 44-amino acid region at the N-terminal end of Arabidopsis ribosomal S6 kinase 1 (AtS6K1) specifically interacted with AtRaptor1, indicating that this region may contain a functional equivalent of the TOS (TOR-Signaling) motif present in the mammalian TOR substrates. Transient over-expression of this 44-amino acid fragment in Arabidopsis protoplasts resulted in significant decrease in rDNA transcription, demonstrating a feasibility of developing a new plant-specific TOR signaling inhibitor based upon perturbation of the Raptor-substrate interaction. - Highlights: • Multiple regions on the Arabidopsis Raptor protein were found to be involved in substrate binding. • N-terminal end of the Arabidopsis ribosomal S6 kinase 1 (AtS6K1) was responsible for interacting with AtRaptor1. • The Raptor-interacting fragment of AtS6K1 could be utilized as an effective inhibitor of plant TOR signaling.

  1. Arabidopsis CDS blastp result: AK288349 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK288349 J090023P19 At2g46590.1 68415.m05811 Dof zinc finger protein DAG2 / Dof affecting germination... 2 (DAG2) identical to SP|Q9ZPY0 DOF zinc finger protein DAG2 (Dof affecting germination 2) {Arabidopsis thaliana} 1e-23 ...

  2. Arabidopsis CDS blastp result: AK241364 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK241364 J065152E11 At2g46590.1 68415.m05811 Dof zinc finger protein DAG2 / Dof affecting germination... 2 (DAG2) identical to SP|Q9ZPY0 DOF zinc finger protein DAG2 (Dof affecting germination 2) {Arabidopsis thaliana} 2e-20 ...

  3. Reference: 439 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available or IID (TFIID) complex. Overexpression of atTAF10 under the control of the 35S promoter in Arabidopsis impro...is TATA box-binding protein (TBP)-associated factor 10 (atTAF10), which constitutes the transcriptional fact

  4. Arabidopsis CDS blastp result: AK064663 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK064663 002-115-A10 At2g34450.1 high mobility group (HMG1/2) family protein simila...r to HMG protein [Arabidopsis thaliana] GI:2832361; contains Pfam profile PF00505: HMG (high mobility group) box 2e-27 ...

  5. Arabidopsis CDS blastp result: AK120871 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK120871 J023026D19 At1g48900.1 signal recognition particle 54 kDa protein 3 / SRP5...4 (SRP-54C) identical to SP|P49967 Signal recognition particle 54 kDa protein 3 (SRP54) {Arabidopsis thaliana} 0.0 ...

  6. Arabidopsis CDS blastp result: AK071661 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK071661 J023105D07 At5g37770.1 touch-responsive protein / calmodulin-related protein 2, touch...-induced (TCH2) identical to calmodulin-related protein 2,touch-induced SP:P25070 from [Arabidopsis thaliana] 3e-33 ...

  7. Arabidopsis CDS blastp result: AK242428 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK242428 J080089P09 At5g37770.1 68418.m04547 touch-responsive protein / calmodulin-related protein 2, touch...-induced (TCH2) identical to calmodulin-related protein 2,touch-induced SP:P25070 from [Arabidopsis thaliana] 9e-19 ...

  8. Arabidopsis CDS blastp result: AK242428 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK242428 J080089P09 At2g41100.1 68415.m05076 touch-responsive protein / calmodulin-related protein 3, touch...-induced (TCH3) identical to calmodulin-related protein 3, touch-induced SP:P25071 from [Arabidopsis thaliana] 8e-18 ...

  9. Arabidopsis CDS blastp result: AK241786 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK241786 J065207F05 At5g37770.1 68418.m04547 touch-responsive protein / calmodulin-related protein 2, touch...-induced (TCH2) identical to calmodulin-related protein 2,touch-induced SP:P25070 from [Arabidopsis thaliana] 1e-19 ...

  10. Arabidopsis CDS blastp result: AK242346 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK242346 J080012M07 At2g41100.1 68415.m05076 touch-responsive protein / calmodulin-related protein 3, touch...-induced (TCH3) identical to calmodulin-related protein 3, touch-induced SP:P25071 from [Arabidopsis thaliana] 8e-44 ...

  11. Arabidopsis CDS blastp result: AK242428 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK242428 J080089P09 At2g41100.1 68415.m05076 touch-responsive protein / calmodulin-related protein 3, touch...-induced (TCH3) identical to calmodulin-related protein 3, touch-induced SP:P25071 from [Arabidopsis thaliana] 2e-14 ...

  12. Arabidopsis CDS blastp result: AK242428 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK242428 J080089P09 At2g41100.2 68415.m05077 touch-responsive protein / calmodulin-related protein 3, touch...-induced (TCH3) identical to calmodulin-related protein 3, touch-induced SP:P25071 from [Arabidopsis thaliana] 3e-16 ...

  13. Arabidopsis CDS blastp result: AK242346 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK242346 J080012M07 At5g37770.1 68418.m04547 touch-responsive protein / calmodulin-related protein 2, touch...-induced (TCH2) identical to calmodulin-related protein 2,touch-induced SP:P25070 from [Arabidopsis thaliana] 2e-11 ...

  14. Arabidopsis CDS blastp result: AK108506 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK108506 002-143-H11 At5g37770.1 touch-responsive protein / calmodulin-related protein 2, touch...-induced (TCH2) identical to calmodulin-related protein 2,touch-induced SP:P25070 from [Arabidopsis thaliana] 7e-14 ...

  15. Arabidopsis CDS blastp result: AK242346 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK242346 J080012M07 At2g41100.1 68415.m05076 touch-responsive protein / calmodulin-related protein 3, touch...-induced (TCH3) identical to calmodulin-related protein 3, touch-induced SP:P25071 from [Arabidopsis thaliana] 4e-41 ...

  16. Arabidopsis CDS blastp result: AK242346 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK242346 J080012M07 At5g37770.1 68418.m04547 touch-responsive protein / calmodulin-related protein 2, touch...-induced (TCH2) identical to calmodulin-related protein 2,touch-induced SP:P25070 from [Arabidopsis thaliana] 2e-25 ...

  17. Arabidopsis CDS blastp result: AK242346 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK242346 J080012M07 At2g41100.2 68415.m05077 touch-responsive protein / calmodulin-related protein 3, touch...-induced (TCH3) identical to calmodulin-related protein 3, touch-induced SP:P25071 from [Arabidopsis thaliana] 3e-26 ...

  18. Arabidopsis CDS blastp result: AK243656 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK243656 J100088L22 At2g41100.1 68415.m05076 touch-responsive protein / calmodulin-related protein 3, touch...-induced (TCH3) identical to calmodulin-related protein 3, touch-induced SP:P25071 from [Arabidopsis thaliana] 1e-19 ...

  19. Arabidopsis CDS blastp result: AK243656 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK243656 J100088L22 At2g41100.2 68415.m05077 touch-responsive protein / calmodulin-related protein 3, touch...-induced (TCH3) identical to calmodulin-related protein 3, touch-induced SP:P25071 from [Arabidopsis thaliana] 5e-20 ...

  20. Arabidopsis CDS blastp result: AK242346 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK242346 J080012M07 At2g41100.2 68415.m05077 touch-responsive protein / calmodulin-related protein 3, touch...-induced (TCH3) identical to calmodulin-related protein 3, touch-induced SP:P25071 from [Arabidopsis thaliana] 3e-44 ...

  1. Arabidopsis CDS blastp result: AK243656 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK243656 J100088L22 At2g41100.1 68415.m05076 touch-responsive protein / calmodulin-related protein 3, touch...-induced (TCH3) identical to calmodulin-related protein 3, touch-induced SP:P25071 from [Arabidopsis thaliana] 2e-17 ...

  2. Arabidopsis CDS blastp result: AK062711 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK062711 001-106-C02 At5g37770.1 touch-responsive protein / calmodulin-related protein 2, touch...-induced (TCH2) identical to calmodulin-related protein 2,touch-induced SP:P25070 from [Arabidopsis thaliana] 9e-34 ...

  3. Arabidopsis CDS blastp result: AK288095 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK288095 J075191E21 At2g41100.1 68415.m05076 touch-responsive protein / calmodulin-related protein 3, touch...-induced (TCH3) identical to calmodulin-related protein 3, touch-induced SP:P25071 from [Arabidopsis thaliana] 2e-16 ...

  4. Arabidopsis CDS blastp result: AK242346 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK242346 J080012M07 At2g41100.1 68415.m05076 touch-responsive protein / calmodulin-related protein 3, touch...-induced (TCH3) identical to calmodulin-related protein 3, touch-induced SP:P25071 from [Arabidopsis thaliana] 3e-26 ...

  5. Arabidopsis CDS blastp result: AK288095 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK288095 J075191E21 At2g41100.2 68415.m05077 touch-responsive protein / calmodulin-related protein 3, touch...-induced (TCH3) identical to calmodulin-related protein 3, touch-induced SP:P25071 from [Arabidopsis thaliana] 2e-15 ...

  6. Arabidopsis CDS blastp result: AK068893 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK068893 J023001G24 At4g15090.1 far-red impaired response protein (FAR1) / far-red impai...red responsive protein (FAR1) identical to far-red impaired response protein FAR1 [Arabidopsis thaliana] gi|5764395|gb|AAD51282; contains Pfam:PF03101 domain: FAR1 family 1e-39 ...

  7. Arabidopsis CDS blastp result: AK241679 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK241679 J065193F24 At3g29410.1 68416.m03695 terpene synthase/cyclase family protein similar to terpene... synthase GB:CAA72074 from [Arabidopsis thaliana], contains Pfam profile: PF01397 terpene synthase family 5e-65 ...

  8. Arabidopsis CDS blastp result: AK242212 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK242212 J075171E13 At3g29410.1 68416.m03695 terpene synthase/cyclase family protein similar to terpene... synthase GB:CAA72074 from [Arabidopsis thaliana], contains Pfam profile: PF01397 terpene synthase family 1e-21 ...

  9. Reference: 486 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available time in many plant species through the photoperiod and vernalization pathways, re...cipates in both the photoperiod and vernalization pathways in Arabidopsis thaliana by regulating expression ... of VIN3 in a photoperiod-dependent manner. A PHD finger protein involved in both the vernalization and photoperiod pathways

  10. Reference: 751 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available 751 http://metadb.riken.jp/db/SciNetS_ria224i/cria224u4ria224u18390806i Sitaraman ...unctions during Arabidopsis embryo and floral development. 2 672-81 18390806 2008 Jun Plant physiology Bui Minh|Liu Zhongchi|Sitaraman Jayashree

  11. Arabidopsis CDS blastp result: AK103126 [KOME

    Lifescience Database Archive (English)

    Full Text Available 0S proteasome beta subunit PBB1 (PBB1) GB:AAC32066 [Arabidopsis thaliana] (Genetics 149 (2), 677-692 (1998)); contains Pfam profile: PF00227 proteasome A-type and B-type; 1e-129 ...

  12. Roles of DNA methyltransferases in Arabidopsis development ...

    African Journals Online (AJOL)

    Mutations that cause severe loss of DNA methylation often leads to abnormal development. In the present review, we summarized recent findings of the three major DNA methyltransferases mutants playing vital role in development of Arabidopsis thaliana. Keywords: DNA methylation, epigenetics, methyltransferase, mutant ...

  13. Arabidopsis CDS blastp result: AK108796 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK108796 002-151-C01 At2g25320.1 meprin and TRAF homology domain-containing protein / MATH... domain-containing protein weak similarity to ubiquitin-specific protease 12 [Arabidopsis thaliana] GI:11993471; contains Pfam profile PF00917: MATH domain 3e-97 ...

  14. Arabidopsis CDS blastp result: AK102133 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK102133 J033085E13 At5g43560.2 meprin and TRAF homology domain-containing protein / MATH... domain-containing protein weak similarity to ubiquitin-specific protease 12 [Arabidopsis thaliana] GI:11993471; contains Pfam profile PF00917: MATH domain 1e-146 ...

  15. Arabidopsis CDS blastp result: AK105718 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK105718 001-201-F09 At5g43560.2 meprin and TRAF homology domain-containing protein / MATH... domain-containing protein weak similarity to ubiquitin-specific protease 12 [Arabidopsis thaliana] GI:11993471; contains Pfam profile PF00917: MATH domain 5e-22 ...

  16. Reference: 438 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

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

  17. Reference: 356 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available 006 Mar Plant molecular biology Deng Xingwang|Dong Li|Wang Lei|Xue Yongbiao|Zhang Yansheng|Zhang Yu'e ...ein CEGENDUO negatively regulates auxin-mediated lateral root formation in Arabidopsis. 4 599-615 16525894 2

  18. Proteomics of Arabidopsis seed germination and priming

    NARCIS (Netherlands)

    Gallardo, K.; Job, C.; Groot, S.P.C.; Puype, M.; Demol, H.; Vandekerckhove, J.; Job, D.

    2003-01-01

    To better understand seed germination, a complex developmental process, we developed a proteome analysis of the model plant Arabidopsis for which complete genome sequence is now available. Among about 1,300 total seed proteins resolved in two-dimensional gels, changes in the abundance (up- and

  19. Reference: 689 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available the high affinity of MOT1 allows plants to obtain scarce Mo from soil. An Arabidopsis thaliana high-affinity... molybdate transporter required for efficient uptake of molybdate from soil. 47 18807-12 18003916 2007 Nov P

  20. Reference: 169 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available e M et al. 2005 Mar. Plant J. 41(5):744-54. The recessive Arabidopsis thalianafumonisin B1-resistant (fbr6) ...opment and sensitivity to fumonisin B1. 5 744-54 15703061 2005 Mar The Plant journal Liang Xinwen|Nekl Emily R|Stiers Justin J|Stone Julie M

  1. Arabidopsis CDS blastp result: AK243131 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK243131 J100030A12 At1g21450.1 68414.m02682 scarecrow-like transcription factor 1 ...(SCL1) identical to scarecrow-like 1 GB:AAF21043 GI:6644390 from [Arabidopsis thaliana] 4e-46 ...

  2. Arabidopsis CDS blastp result: AK242412 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK242412 J080076J05 At1g21450.1 68414.m02682 scarecrow-like transcription factor 1 ...(SCL1) identical to scarecrow-like 1 GB:AAF21043 GI:6644390 from [Arabidopsis thaliana] 1e-36 ...

  3. Arabidopsis CDS blastp result: AK065420 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK065420 J013022D10 At5g13630.1 magnesium-chelatase subunit chlH, chloroplast, puta...tive / Mg-protoporphyrin IX chelatase, putative (CHLH) nearly identical to magnesium chelatase subunit GI:11...54627 from [Arabidopsis thaliana]; contains Pfam profile: PF02514 CobN/magnesium chelatase family protein 1e-166 ...

  4. Arabidopsis CDS blastp result: AK062262 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK062262 001-047-H04 At5g13630.1 magnesium-chelatase subunit chlH, chloroplast, put...ative / Mg-protoporphyrin IX chelatase, putative (CHLH) nearly identical to magnesium chelatase subunit GI:1...154627 from [Arabidopsis thaliana]; contains Pfam profile: PF02514 CobN/magnesium chelatase family protein 0.0 ...

  5. Arabidopsis CDS blastp result: AK069545 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK069545 J023025I06 At5g13630.1 magnesium-chelatase subunit chlH, chloroplast, puta...tive / Mg-protoporphyrin IX chelatase, putative (CHLH) nearly identical to magnesium chelatase subunit GI:11...54627 from [Arabidopsis thaliana]; contains Pfam profile: PF02514 CobN/magnesium chelatase family protein 0.0 ...

  6. Arabidopsis CDS blastp result: AK067323 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK067323 J013106B16 At5g13630.1 magnesium-chelatase subunit chlH, chloroplast, puta...tive / Mg-protoporphyrin IX chelatase, putative (CHLH) nearly identical to magnesium chelatase subunit GI:11...54627 from [Arabidopsis thaliana]; contains Pfam profile: PF02514 CobN/magnesium chelatase family protein 0.0 ...

  7. Arabidopsis CDS blastp result: AK060612 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK060612 001-025-F03 At5g13630.1 magnesium-chelatase subunit chlH, chloroplast, put...ative / Mg-protoporphyrin IX chelatase, putative (CHLH) nearly identical to magnesium chelatase subunit GI:1...154627 from [Arabidopsis thaliana]; contains Pfam profile: PF02514 CobN/magnesium chelatase family protein 0.0 ...

  8. Arabidopsis CDS blastp result: AK107208 [KOME

    Lifescience Database Archive (English)

    Full Text Available Ala hydrolase, putative virtually identical to gr1-protein from [Arabidopsis thaliana] GI:3559811; similar t...AK107208 002-125-B11 At1g44350.1 IAA-amino acid hydrolase 6, putative (ILL6) / IAA-

  9. Arabidopsis CDS blastp result: AK065124 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK065124 J013001P04 At1g44446.1 chlorophyll a oxygenase (CAO) / chlorophyll b synthase identical to chloroph...yll a oxygenase GI:5853117 from [Arabidopsis thaliana]; contains Pfam PF00355 Rieske [2Fe-2S] domain 0.0 ...

  10. Arabidopsis CDS blastp result: AK067730 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK067730 J013116K15 At1g44446.1 chlorophyll a oxygenase (CAO) / chlorophyll b synthase identical to chloroph...yll a oxygenase GI:5853117 from [Arabidopsis thaliana]; contains Pfam PF00355 Rieske [2Fe-2S] domain 0.0 ...

  11. Arabidopsis CDS blastp result: AK103940 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK103940 001-013-G08 At5g54190.1 protochlorophyllide reductase A, chloroplast / PCR A / NADPH-protochlorophy...llide oxidoreductase A (PORA) identical to SP:Q42536 protochlorophyllide reductase ...A, chloroplast precursor (EC 1.3.1.33) (PCR A) (NADPH-protochlorophyllide oxidoreductase A) (POR A) [Arabidopsis thaliana] 1e-130 ...

  12. Arabidopsis CDS blastp result: AK063367 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK063367 001-114-D11 At1g44446.1 chlorophyll a oxygenase (CAO) / chlorophyll b synthase identical to chlorop...hyll a oxygenase GI:5853117 from [Arabidopsis thaliana]; contains Pfam PF00355 Rieske [2Fe-2S] domain 0.0 ...

  13. Arabidopsis CDS blastp result: AK071899 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK071899 J013059G06 At1g44446.1 chlorophyll a oxygenase (CAO) / chlorophyll b synthase identical to chloroph...yll a oxygenase GI:5853117 from [Arabidopsis thaliana]; contains Pfam PF00355 Rieske [2Fe-2S] domain 1e-154 ...

  14. Arabidopsis CDS blastp result: AK104855 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK104855 001-043-B11 At5g54190.1 protochlorophyllide reductase A, chloroplast / PCR A / NADPH-protochlorophy...llide oxidoreductase A (PORA) identical to SP:Q42536 protochlorophyllide reductase ...A, chloroplast precursor (EC 1.3.1.33) (PCR A) (NADPH-protochlorophyllide oxidoreductase A) (POR A) [Arabidopsis thaliana] 1e-130 ...

  15. Arabidopsis CDS blastp result: AK105724 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK105724 001-201-G07 At1g07110.1 fructose-6-phosphate 2-kinase / fructose-2,6-bisph...osphatase (F2KP) identical to fructose-6-phosphate 2-kinase/fructose-2,6-bisphosphatase (F2KP) [Arabidopsis thaliana] GI:13096098 0.0 ...

  16. Arabidopsis CDS blastp result: AK106106 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK106106 001-207-C12 At1g07110.1 fructose-6-phosphate 2-kinase / fructose-2,6-bisph...osphatase (F2KP) identical to fructose-6-phosphate 2-kinase/fructose-2,6-bisphosphatase (F2KP) [Arabidopsis thaliana] GI:13096098 9e-39 ...

  17. Arabidopsis CDS blastp result: AK072243 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK072243 J023003N10 At1g07110.1 fructose-6-phosphate 2-kinase / fructose-2,6-bispho...sphatase (F2KP) identical to fructose-6-phosphate 2-kinase/fructose-2,6-bisphosphatase (F2KP) [Arabidopsis thaliana] GI:13096098 0.0 ...

  18. Arabidopsis CDS blastp result: AK065086 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK065086 J013001L18 At1g07110.1 fructose-6-phosphate 2-kinase / fructose-2,6-bispho...sphatase (F2KP) identical to fructose-6-phosphate 2-kinase/fructose-2,6-bisphosphatase (F2KP) [Arabidopsis thaliana] GI:13096098 0.0 ...

  19. Arabidopsis CDS blastp result: AK105066 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK105066 001-044-F12 At1g07110.1 fructose-6-phosphate 2-kinase / fructose-2,6-bisph...osphatase (F2KP) identical to fructose-6-phosphate 2-kinase/fructose-2,6-bisphosphatase (F2KP) [Arabidopsis thaliana] GI:13096098 1e-166 ...

  20. Arabidopsis CDS blastp result: AK069285 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK069285 J023011N22 At1g07110.1 fructose-6-phosphate 2-kinase / fructose-2,6-bispho...sphatase (F2KP) identical to fructose-6-phosphate 2-kinase/fructose-2,6-bisphosphatase (F2KP) [Arabidopsis thaliana] GI:13096098 0.0 ...