The plant innate immunity response in stomatal guard cells invokes G-protein-dependent ion channel regulation.
The plant innate immunity response in stomatal guard cells invokes G-protein-dependent ion channel regulation.
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DOI：
10.1111/j.1365-313x.2008.03657.x
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发表时间：
2008-12
期刊：
影响因子：
--
通讯作者：
Assmann SM
中科院分区：
文献类型：
--
作者：
Zhang W;He SY;Assmann SM
气孔是陆生植物吸收CO2和蒸腾失水的重要途径，也是病原菌侵染的潜在通道。气孔的开闭受不同的机制控制。拟南芥气孔已经显示出响应于细菌和病原体相关分子模式（PAMP）而关闭，作为PAMP触发的免疫（PTI）的一部分。在这里，我们表明，flg22，PAMP来自细菌鞭毛蛋白，也抑制光诱导的气孔开放。与我们对气孔开放的观察一致，flg22抑制保卫细胞内向K+通道（K+电流），介导气孔开放过程中的K+吸收。与先前记录的由外源性H2O2和一氧化氮（NO）升高触发的K+电流变化类似，随着flg22暴露持续时间的延长，保卫细胞的外向K+通道（K+输出电流）也被抑制。在flg22受体的无效突变体中，FLS2、flg22对气孔开放、K+电流和K+输出电流的调节被消除。flg22也不能在唯一典型G蛋白α亚基GPA1的无效突变体中引发这些反应。细菌毒素冠菌素，产生的几个致病菌株的假单胞菌，逆转flg22对钾离子电流和气孔开放的抑制作用，表明植物和病原体之间的相互作用，在植物离子通道的调节。因此，PAMP触发的气孔反应涉及K+通道调节，并且这种调节依赖于通过同源PAMP受体和异源三聚体G蛋白的信号传导。这些新的发现为PTI相关的保卫细胞反应提供了很大程度上难以捉摸的信号传导过程的见解。
Stomata in the epidermes of terrestrial plants are important for CO2 absorption and transpirational water loss, and are also potential entryways for pathogen infection. Stomatal opening and closure are controlled by distinct mechanisms. Arabidopsis stomata have been shown to close in response to bacteria and pathogen-associated molecular patterns (PAMPs) as part of PAMP-triggered immunity (PTI). Here we show that flg22, a PAMP derived from bacterial flagellin, also inhibits light-induced stomatal opening. Consistent with our observations on stomatal opening, flg22 inhibits the guard cell inward K+ channels (K+in currents) that mediate K+ uptake during stomatal opening. Similar to previously documented K+ current changes triggered by exogenous elevation of H2O2 and nitric oxide (NO), with prolonged duration of flg22 exposure the outward K+ channels (K+out currents) of guard cells are also inhibited. In null mutants of the flg22 receptor, FLS2, flg22 regulation of stomatal opening, K+ currents, and K+out currents is eliminated. flg22 also fails to elicit these responses in null mutants of the sole canonical G protein α subunit, GPA1. The bacterial toxin, coronatine, produced by several pathogenic strains of Pseudomonas syringae, reverses the inhibitory effects of flg22 on both K+in currents and stomatal opening, indicating interplay between plant and pathogen in the regulation of plant ion channels. Thus, PAMP-triggered stomatal response involves K+ channel regulation, and this regulation is dependent on signaling via cognate PAMP receptors and a heterotrimeric G-protein. These new findings provide insights into the largely elusive signaling process underlying PTI-associated guard cell responses.