H2O2 and cytosolic Ca2+ signals triggered by the PM H+‐coupled transport system mediate K+/Na+ homeostasis in NaCl‐stressed Populus euphratica cells |
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Authors: | JIAN SUN MEI‐JUAN WANG MING‐QUAN DING SHU‐RONG DENG MEI‐QIN LIU CUN‐FU LU XIAO‐YANG ZHOU XIN SHEN XIAO‐JIANG ZHENG ZENG‐KAI ZHANG JIN SONG ZAN‐MIN HU YUE XU SHAO‐LIANG CHEN |
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Affiliation: | 1. College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, China,;2. Key Laboratory of Biological Resources Protection and Utilization in Hubei Province, Hubei University for Nationalities, Enshi 445000, China,;3. Xuyue (Beijing) Science and Technology Co., Ltd., Beijing 100080, China and;4. Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China |
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Abstract: | Using confocal microscopy, X‐ray microanalysis and the scanning ion‐selective electrode technique, we investigated the signalling of H2O2, cytosolic Ca2+ ([Ca2+]cyt) and the PM H+‐coupled transport system in K+/Na+ homeostasis control in NaCl‐stressed calluses of Populus euphratica. An obvious Na+/H+ antiport was seen in salinized cells; however, NaCl stress caused a net K+ efflux, because of the salt‐induced membrane depolarization. H2O2 levels, regulated upwards by salinity, contributed to ionic homeostasis, because H2O2 restrictions by DPI or DMTU caused enhanced K+ efflux and decreased Na+/H+ antiport activity. NaCl induced a net Ca2+ influx and a subsequent rise of [Ca2+]cyt, which is involved in H2O2‐mediated K+/Na+ homeostasis in salinized P. euphratica cells. When callus cells were pretreated with inhibitors of the Na+/H+ antiport system, the NaCl‐induced elevation of H2O2 and [Ca2+]cyt was correspondingly restricted, leading to a greater K+ efflux and a more pronounced reduction in Na+/H+ antiport activity. Results suggest that the PM H+‐coupled transport system mediates H+ translocation and triggers the stress signalling of H2O2 and Ca2+, which results in a K+/Na+ homeostasis via mediations of K+ channels and the Na+/H+ antiport system in the PM of NaCl‐stressed cells. Accordingly, a salt stress signalling pathway of P. euphratica cells is proposed. |
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Keywords: | confocal microscopy NaCl signalling poplar SIET X‐ray microanalysis |
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