A Signaling Pathway Linking Nitric Oxide Production to Heterotrimeric G Protein and Hydrogen Peroxide Regulates Extracellular Calmodulin Induction of Stomatal Closure in Arabidopsis
A Signaling Pathway Linking Nitric Oxide Production to Heterotrimeric G Protein and Hydrogen Peroxide Regulates Extracellular Calmodulin Induction of Stomatal Closure in Arabidopsis
复制标题
连接一氧化氮产生与异三聚体 G 蛋白和过氧化氢的信号通路调节细胞外钙调蛋白诱导拟南芥气孔关闭
DOI：
10.1104/pp.109.137067
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发表时间：
2009-05-01
期刊：
影响因子：
7.4
通讯作者：
Chen, Yu-Ling
中科院分区：
文献类型：
--
作者：
Li, Jian-Hua;Liu, Yin-Qian;Chen, Yu-Ling
细胞外钙调蛋白（Extracellular calmodulin, ExtCaM）通过诱导包括异三聚体G蛋白、过氧化氢（H2O2）和Ca2+在内的细胞内信号事件级联来调节气孔运动。然而，extcam介导的保护细胞信号通路仍然知之甚少。在本报告中，我们发现拟南芥（Arabidopsis thaliana）一氧化氮相关1 （AtNOA1）依赖的一氧化氮（NO）积累在extcam诱导的气孔关闭中起着至关重要的作用。在野生型中，ExtCaM触发了与气孔关闭相关的NO水平的显著增加，但在Atnoa1突变体中，这两种效应都被消除了。此外，我们发现extcam介导的NO生成受GPA1（异源三聚体G蛋白的G α亚基）的调控。在gpa1敲除突变体中，依赖extcam的NO积累被消除，但gpa1的组成活性形式（cG α）的过表达增强了NO积累。此外，cG α Atnoa1和gpa1-2 Atnoa1双突变体表现出与Atnoa1相似的反应。通过过表达AtNOA1修复gpa1缺陷。最后，我们证明了G蛋白的活化依赖于H2O2的产生。保护细胞中H2O2水平的降低阻断了cG α细胞系的气孔响应，而外源H2O2修复了gpa1突变体中extcam介导的气孔关闭缺陷。此外，保护细胞中缺乏NADPH氧化酶活性的atrbohD/F突变体在ExtCaM作用下产生NO受到损害，在Atnoa1中h2o2诱导的气孔关闭和NO积累受到严重损害。这些发现已经建立了一个导致extcam诱导的气孔关闭的信号通路，该信号通路涉及gpa1依赖性的H2O2生成激活和随后的atnoa1依赖性的NO积累。
Extracellular calmodulin (ExtCaM) regulates stomatal movement by eliciting a cascade of intracellular signaling events including heterotrimeric G protein, hydrogen peroxide (H2O2), and Ca2+. However, the ExtCaM-mediated guard cell signaling pathway remains poorly understood. In this report, we show that Arabidopsis (Arabidopsis thaliana) NITRIC OXIDE ASSOCIATED1 (AtNOA1)-dependent nitric oxide (NO) accumulation plays a crucial role in ExtCaM-induced stomatal closure. ExtCaM triggered a significant increase in NO levels associated with stomatal closure in the wild type, but both effects were abolished in the Atnoa1 mutant. Furthermore, we found that ExtCaM-mediated NO generation is regulated by GPA1, the G alpha-subunit of heterotrimeric G protein. The ExtCaM-dependent NO accumulation was nullified in gpa1 knockout mutants but enhanced by overexpression of a constitutively active form of GPA1 (cG alpha). In addition, cG alpha Atnoa1 and gpa1-2 Atnoa1 double mutants exhibited a similar response as did Atnoa1. The defect in gpa1 was rescued by overexpression of AtNOA1. Finally, we demonstrated that G protein activation of NO production depends on H2O2. Reduced H2O2 levels in guard cells blocked the stomatal response of cG alpha lines, whereas exogenously applied H2O2 rescued the defect in ExtCaM-mediated stomatal closure in gpa1 mutants. Moreover, the atrbohD/F mutant, which lacks the NADPH oxidase activity in guard cells, had impaired NO generation in response to ExtCaM, and H2O2-induced stomatal closure and NO accumulation were greatly impaired in Atnoa1. These findings have established a signaling pathway leading to ExtCaM-induced stomatal closure, which involves GPA1-dependent activation of H2O2 production and subsequent AtNOA1-dependent NO accumulation.