拟南芥钙依赖蛋白激酶CDPKs调控植物应答水淹胁迫的分子机理

水淹造成的低氧胁迫和水淹退去后复氧阶段的脱水和氧化胁迫，均严重影响植物生长和发育。低氧和复氧胁迫都会诱导活性氧（ROS）爆发，但目前对于水淹胁迫下植物细胞内ROS的调控机制还不清楚。申请人前期工作发现，拟南芥钙依赖蛋白激酶CDPK16和CDPK18在水淹处理前后表达水平显著性差异，暗示CDPK16/18可能参与植物低氧应答。表型分析发现，CDPK16/18-OEs对水淹胁迫非常敏感，而cdpk16/18双突变体则表现出增强的耐受性，且双突变体中游离钙离子浓度显著升高。蛋白互作实验表明，CDPK16/18与NADPH氧化酶RbohD及乙烯响应转录因子HRE1相互作用，提示CDPK16/18可能是整合Ca2+信号、ROS信号和激素信号，调控植物应答水淹胁迫的关键因子。本项目拟通过遗传学和生化手段，深入探究CDPK16/18参与植物响应水淹胁迫的生物学功能和作用机理。

Hypoxia and dehydration/oxidative stress caused by submergence and post- submergence reoxygenation, respectively, restricts plant growth and development. In plant cells, the reactive oxygen species (ROS) production is accumulated during either hypoxia or reoxygenation stresses; however, little is known about the transcriptional regulation of ROS signaling in plant response to submergence stress. Our preliminary data showed the transcripts of plant Calcium-Dependent Protein Kinase(CDPK)，CDPK16 and CDPK18 were significantly up-regulated upon submergence treatment in Arabidopsis thaliana, indicating that these two protein kinases are likely involved in the regulation of hypoxia responses. The CDPK-overexpressor (CDPK16-OEs and CDPK18-OEs) displayed hypersensitivity, while their double knockout lines (cdpk16/18) showed enhanced tolerance, to submergence compared to that of wild type. Moreover, the cdpk16/18 double mutant had better Ca2+ retention ability compared with those of WT and CDPK-overexpressor plants under hypoxia. Furthermore, CDPK16 and CDPK18 interacted in planta with respiratory burst oxidase homolog D (RbohD) and the ethylene response transcription factor HRE1. These results indicated that Arabidopsis CDPK16 /18 may function as key regulators in integrating Ca2+ signaling, ROS signaling, and ethylene pathway in plant responses to submergence. By genetic and biochemical approaches, this study further intends to elucidate the molecular mechanism of how CDPKs integrate with ROS signaling and hormone pathways to regulate submergence response in Arabidopsis.