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      Fibre elongation requires normal redox homeostasis modulated by cytosolic ascorbate peroxidase in cotton ( Gossypium hirsutum)


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          Optimal H 2O 2 levels and redox state regulated by cytosolic ascorbate peroxidase are key mechanisms regulating fibre elongation in cotton.


          High-quality cotton fibre equates to a more comfortable textile. Fibre length is an important index of fibre quality. Hydrogen peroxide (H 2O 2) acts as a signalling molecule in the regulation of fibre elongation. Results from in vitro ovule culture suggest that the alteration of fibre cell H 2O 2 levels affects fibre development. Ascorbate peroxidase (APX) is an important reactive oxygen species (ROS) scavenging enzyme, and we found that GhAPX1A T/D T encoded one member of the previously unrealized group of cytosolic APXs (cAPXs) that were preferentially expressed during the fibre elongation stage. Transgenic cottons with up- and down-regulation of GhAPX1A T/D T were generated to control fibre endogenous levels of H 2O 2. Suppression of all cAPX (IAO) resulted in a 3.5-fold increase in H 2O 2 level in fibres and oxidative stress, which significantly suppressed fibre elongation. The fibre length of transgenic lines with over-expression or specific down-regulation of GhAPX1A T/D T did not show any obvious change. However, the fibres in the over-expression lines exhibited higher tolerance to oxidative stress. Differentially expressed genes (DEGs) in fibres at 10 days post-anthesis (DPA) of IAO lines identified by RNA-seq were related to redox homeostasis, signalling pathways, stress responses and cell wall synthesis, and the DEGs that were up-regulated in IAO lines were also up-regulated in the 10 DPA and 20 DPA fibres of wild cotton compared with domesticated cotton. These results suggest that optimal H 2O 2 levels and redox state regulated by cytosolic APX are key mechanisms regulating fibre elongation, and dysregulation of the increase in H 2O 2 induces oxidative stress and results in shorter fibres by initiating secondary cell wall-related gene expression.

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          Most cited references 29

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          Reactive oxygen species produced by NADPH oxidase regulate plant cell growth.

          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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            Calcium channels activated by hydrogen peroxide mediate abscisic acid signalling in guard cells.

             S Thomine,  Y Murata,  Z. Pei (2000)
            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.
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              A burst of plant NADPH oxidases.

              Reactive oxygen species (ROS) are highly reactive molecules able to damage cellular components but they also act as cell signalling elements. ROS are produced by many different enzymatic systems. Plant NADPH oxidases, also known as respiratory burst oxidase homologues (RBOHs), are the most thoroughly studied enzymatic ROS-generating systems and our understanding of their involvement in various plant processes has increased considerably in recent years. In this review we discuss their roles as ROS producers during cell growth, plant development and plant response to abiotic environmental constraints and biotic interactions, both pathogenic and symbiotic. This broad range of functions suggests that RBOHs may serve as important molecular 'hubs' during ROS-mediated signalling in plants. Copyright © 2011 Elsevier Ltd. All rights reserved.

                Author and article information

                J Exp Bot
                J. Exp. Bot
                Journal of Experimental Botany
                Oxford University Press (UK )
                May 2016
                17 April 2016
                17 April 2016
                : 67
                : 11
                : 3289-3301
                National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University , Wuhan 430070, Hubei, China
                Author notes

                Editor: Karl-Josef Dietz, Bielefeld University

                © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

                This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/3.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.

                Page count
                Pages: 13
                Funded by: National Natural Science Foundation of China http://dx.doi.org/10.13039/501100001809
                Award ID: No. 31230056
                Research Paper


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