Reactive oxygen species produced by nadph oxidase regulate plant cell growth
TL;DR: It is shown here that RHD2 is an NADPH oxidase, a protein that transfers electrons from NADPH to an electron acceptor leading to the formation of reactive oxygen species (ROS) and that ROS accumulate in growing wild-type (WT) root hairs but their levels are markedly decreased in rhd2 mutants.
Abstract: Cell expansion is a central process in plant morphogenesis, and the elongation of roots and root hairs is essential for uptake of minerals and water from the soil. Ca2+ influx from the extracellular store is required for (and sets the rates of) cell elongation in roots. Arabidopsis thaliana rhd2 mutants are defective in Ca2+ uptake and consequently cell expansion is compromised--rhd2 mutants have short root hairs and stunted roots. To determine the regulation of Ca2+ acquisition in growing root cells we show here that RHD2 is an NADPH oxidase, a protein that transfers electrons from NADPH to an electron acceptor leading to the formation of reactive oxygen species (ROS). We show that ROS accumulate in growing wild-type (WT) root hairs but their levels are markedly decreased in rhd2 mutants. Blocking the activity of the NADPH oxidase with diphenylene iodonium (DPI) inhibits ROS formation and phenocopies Rhd2-. Treatment of rhd2 roots with ROS partly suppresses the mutant phenotype and stimulates the activity of plasma membrane hyperpolarization-activated Ca2+ channels, the predominant root Ca2+ acquisition system. This indicates that NADPH oxidases control development by making ROS that regulate plant cell expansion through the activation of Ca2+ channels.
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TL;DR: The biochemistry of ROS and their production sites, and ROS scavenging antioxidant defense machinery are described, which protects plants against oxidative stress damages.
8,259 citations
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...photorespiration and photosynthesis [39], stomatal movement [40], cell cycle [15] and growth and development [41]....
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TL;DR: This review summarizes the current state of knowledge of the functions of NOX enzymes in physiology and pathology.
Abstract: For a long time, superoxide generation by an NADPH oxidase was considered as an oddity only found in professional phagocytes. Over the last years, six homologs of the cytochrome subunit of the phag...
5,873 citations
TL;DR: In Arabidopsis, a network of at least 152 genes is involved in managing the level of ROS, and this network is highly dynamic and redundant, and encodes ROS-scavenging and ROS-producing proteins.
4,902 citations
TL;DR: Recent advances in elucidating the role of root exudates in interactions between plant roots and other plants, microbes, and nematodes present in the rhizosphere are described.
Abstract: The rhizosphere encompasses the millimeters of soil surrounding a plant root where complex biological and ecological processes occur. This review describes recent advances in elucidating the role of root exudates in interactions between plant roots and other plants, microbes, and nematodes present in the rhizosphere. Evidence indicating that root exudates may take part in the signaling events that initiate the execution of these interactions is also presented. Various positive and negative plant-plant and plant-microbe interactions are highlighted and described from the molecular to the ecosystem scale. Furthermore, methodologies to address these interactions under laboratory conditions are presented.
3,674 citations
TL;DR: Growing evidence suggests a model for redox homeostasis in which the reactive oxygen species (ROS)–antioxidant interaction acts as a metabolic interface for signals derived from metabolism and from the environment.
Abstract: Low molecular weight antioxidants, such as ascorbate, glutathione, and tocopherol, are information-rich redox buffers that interact with numerous cellular components. In addition to crucial roles in defense and as enzyme cofactors, cellular antioxidants influence plant growth and development by modulating processes from mitosis and cell elongation to senescence and death (De Pinto and De Gara, 2004; Potters et al., 2004; Tokunaga et al., 2005). Most importantly, antioxidants provide essential information on cellular redox state, and they influence gene expression associated with biotic and abiotic stress responses to maximize defense. Growing evidence suggests a model for redox homeostasis in which the reactive oxygen species (ROS)–antioxidant interaction acts as a metabolic interface for signals derived from metabolism and from the environment. This interface modulates the appropriate induction of acclimation processes or, alternatively, execution of cell death programs.
2,543 citations
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...Increases in cytosolic calcium are also triggered by ROS production during root hair formation and abscisic acid signaling (Foreman et al., 2003; Kwak et al., 2003)....
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References
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TL;DR: A new criterion for triggering the extension of word hits, combined with a new heuristic for generating gapped alignments, yields a gapped BLAST program that runs at approximately three times the speed of the original.
Abstract: The BLAST programs are widely used tools for searching protein and DNA databases for sequence similarities. For protein comparisons, a variety of definitional, algorithmic and statistical refinements described here permits the execution time of the BLAST programs to be decreased substantially while enhancing their sensitivity to weak similarities. A new criterion for triggering the extension of word hits, combined with a new heuristic for generating gapped alignments, yields a gapped BLAST program that runs at approximately three times the speed of the original. In addition, a method is introduced for automatically combining statistically significant alignments produced by BLAST into a position-specific score matrix, and searching the database using this matrix. The resulting Position-Specific Iterated BLAST (PSIBLAST) program runs at approximately the same speed per iteration as gapped BLAST, but in many cases is much more sensitive to weak but biologically relevant sequence similarities. PSI-BLAST is used to uncover several new and interesting members of the BRCT superfamily.
70,111 citations
TL;DR: The sensitivity of the commonly used progressive multiple sequence alignment method has been greatly improved and modifications are incorporated into a new program, CLUSTAL W, which is freely available.
Abstract: The sensitivity of the commonly used progressive multiple sequence alignment method has been greatly improved for the alignment of divergent protein sequences. Firstly, individual weights are assigned to each sequence in a partial alignment in order to down-weight near-duplicate sequences and up-weight the most divergent ones. Secondly, amino acid substitution matrices are varied at different alignment stages according to the divergence of the sequences to be aligned. Thirdly, residue-specific gap penalties and locally reduced gap penalties in hydrophilic regions encourage new gaps in potential loop regions rather than regular secondary structure. Fourthly, positions in early alignments where gaps have been opened receive locally reduced gap penalties to encourage the opening up of new gaps at these positions. These modifications are incorporated into a new program, CLUSTAL W which is freely available.
63,427 citations
Book•
13 Jun 1985
TL;DR: 1. Oxygen is a toxic gas - an introduction to oxygen toxicity and reactive species, and the chemistry of free radicals and related 'reactive species'
Abstract: 1. Oxygen is a toxic gas - an introductionto oxygen toxicity and reactive species 2. The chemistry of free radicals and related 'reactive species' 3. Antioxidant defences Endogenous and Diet Derived 4. Cellular responses to oxidative stress: adaptation, damage, repair, senescence and death 5. Measurement of reactive species 6. Reactive species can pose special problems needing special solutions. Some examples. 7. Reactive species can be useful some more examples 8. Reactive species can be poisonous: their role in toxicology 9. Reactive species and disease: fact, fiction or filibuster? 10. Ageing, nutrition, disease, and therapy: A role for antioxidants?
21,528 citations
"Reactive oxygen species produced by..." refers background in this paper
...) can then be readily converted to hydroxyl radicals (OH · ) in the presence of transition metals (such as Cu 2p or Fe 2p...
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TL;DR: TreeView is a simple, easy to use phylogenetic tree viewing utility that runs under both MacOS (on Apple Macintosh computers) and under Microsoft Windows on Intel based computers, the two most common personal computers used by biologists.
Abstract: TreeView is a simple, easy to use phylogenetic tree viewing utility that runs under both MacOS (on Apple Macintosh computers) and under Microsoft Windows on Intel based computers, the two most common personal computers used by biologists. Some phylogeny programs, such as PAUP (Swofford, 1993) and MacClade (Maddison and Maddison, 1992) already provide excellent tree drawing and printing facilities, however at present these programs are restricted to Apple Macintosh computers. Furthermore, they require the user to load a data set before any trees can be displayed which is inconvenient if the user simply wants to view the trees. More portable programs, such as DRAWGRAM and DRAWTREE in the PHYLIP package (Felsenstein, 1993) can run on both MacOS and Windows computers, but make little, if any use of the graphical interface features available under those operating systems. TreeView runs as a native application on either MacOS or Windows computers, enables the user to use the standard fonts installed on their machine, their printer, and supports the relevant native graphics format (PICT and Windows metafile) for either creating graphics files or pasting pictures to other applications via the clipboard. The program also supports standard file operations, such as 'drag and drop' whereby dragging a file's icon onto the program opens that file. TreeView can read a range of tree file formats (see below) and can display trees in a range of styles (Fig. 1). Additional information, such as edge lengths and internal node labels can also be displayed. The order of the terminal taxa in the tree can be altered, and the tree can be rerooted. If the tree file contains more than one tree the user can view each tree in turn. The program can also save trees in a variety of file formats, so that it can be used to move trees between programs that use different file formats.
10,368 citations
TL;DR: Activation of Ca2+-permeable channels in the plasma membrane of Arabidopsis guard cells by hydrogen peroxide indicates that ABA-induced H2O2 production and the H 2O 2-activated Ca2-activated channels are important mechanisms for A BA-induced stomatal closing.
Abstract: Drought is a major threat to agricultural production. Plants synthesize the hormone abscisic acid (ABA) in response to drought, triggering a signalling cascade in guard cells that results in stomatal closure, thus reducing water loss. ABA triggers an increase in cytosolic calcium in guard cells ([Ca2+]cyt) that has been proposed to include Ca2+ influx across the plasma membrane. However, direct recordings of Ca2+ currents have been limited and the upstream activation mechanisms of plasma membrane Ca2+ channels remain unknown. Here we report activation of Ca2+-permeable channels in the plasma membrane of Arabidopsis guard cells by hydrogen peroxide. The H2O2-activated Ca2+ channels mediate both influx of Ca2+ in protoplasts and increases in [Ca2+]cyt in intact guard cells. ABA induces the production of H2O2 in guard cells. If H2O2 production is blocked, ABA-induced closure of stomata is inhibited. Moreover, activation of Ca2+ channels by H2O2 and ABA- and H2O2-induced stomatal closing are disrupted in the recessive ABA-insensitive mutant gca2. These data indicate that ABA-induced H2O2 production and the H2O2-activated Ca2+ channels are important mechanisms for ABA-induced stomatal closing.
1,975 citations
"Reactive oxygen species produced by..." refers background in this paper
...Hydrogen peroxide (which is known to activate guard-cell Ca 2p channel...
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