Reevaluation of the role of chloroplasts in the calsium signaling in guard cells

重新评估叶绿体在保卫细胞钙信号传导中的作用

基本信息

批准号：
18570048
负责人：
SHIINA Takashi
金额：
$ 2.57万
依托单位：
Kyoto Prefectural University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

项目摘要

The role of guard cell chloroplasts in stomatal function is controversial. It is usually assumed that stomatal closure is preceded by a transient increase in cytosolic free Ca^<2+> concentration (Ca^<2+>)_<cyt>) in the guard cells. CAS (Ca^<2+> sensing receptor) is a plant-specific putative Ca^<2+>-binding protein. We foundthat CAS is an integral thylakoid membrane protein, and the N-terminus acidic Ca^<2+>-binding region is likely exposed to the stromal side of the membrane. CAS is essential for stomatal closure induced by external Ca^<2+>. These results provide the evidence that chloroplasts play a critical role in the generation of extracellular Ca^<2+>([Ca^<2+>]_<ext>)-induced[Ca^<2+>]_<cyt> transients and stomatal closure in Arabidopsis.In addition, we founs that extracellular abiotic and pathogen-related stress signals are relayed quickly to chloroplasts, and evoke rapid and transient increases in stromal Ca^<2+> concentration in a stress-dependent manner. Furthermore we demonstrated that CAS is also related to the generation of stromal Ca2+ transients induced by pathogen elicitors and/or light to dark transition. Furthermore, we demonstrated that CAS regulates a multitude of plant innate immune responses, such as flg22-induced stomatal closure, expression of pathogen-related genes, ROS production and a resistance (R) gene-triggered hypersensitive cell death in Arabidopsis. It should be noted that cas-1 shows no significant growth phenotype. These results may have implications for a far more important role of chloroplasts in the regulation of plant innate immune response than was thought.

保卫细胞叶绿体在气孔功能中的作用存在争议。通常假设气孔关闭之前是保卫细胞中胞质游离Ca^2+浓度(Ca^2+)_<cyt>)的短暂增加。 CAS（Ca ^ 2+ 传感受体）是植物特异性的假定Ca ^ 2+ -结合蛋白。我们发现CAS是一种完整的类囊体膜蛋白，并且N末端酸性Ca^2+结合区域可能暴露于膜的基质侧。 CAS对于外部Ca 2+ 诱导的气孔关闭是必需的。这些结果证明叶绿体在细胞外 Ca^<2+>([Ca^<2+>]_<ext>) 诱导的 [Ca^<2+>]_<cyt> 的生成中发挥着关键作用。此外，我们发现细胞外非生物和病原体相关的应激信号会快速传递到叶绿体，并引起基质中快速和短暂的增加Ca 2+ 浓度以应力依赖性方式。此外，我们证明 CAS 还与病原体激发子和/或光暗转变诱导的基质 Ca2+ 瞬变的产生有关。此外，我们证明 CAS 调节多种植物先天免疫反应，例如拟南芥中 flg22 诱导的气孔关闭、病原体相关基因的表达、ROS 产生和抗性 (R) 基因触发的超敏细胞死亡。应该指出的是，cas-1没有显示出显着的生长表型。这些结果可能表明叶绿体在调节植物先天免疫反应中的作用比人们想象的要重要得多。