组氨酸激酶RetS在猕猴桃细菌性溃疡病菌低温致病过程中的作用机制研究

由丁香假单胞菌猕猴桃致病变种（Pseudomonas syringae pv. actinidiae, Psa）引起的猕猴桃溃疡病已成为世界猕猴桃生产中的毁灭性病害，温度对溃疡病始发期的早晚、扩展速度、发病程度和蔓延都起着重要作用，然而关于其对病原菌毒力因子调控的分子机制尚未见报到。项目组前期通过测定不同温度条件下溃疡病菌的转录组数据发现，组氨酸激酶RetS与溃疡病菌低温条件下的致病力相关。本研究在此基础上，拟通过生物信息学方法分析该基因序列、蛋白结构特征和磷酸化位点，通过构建基因敲除、回复突变体和磷酸化位点定点突变体，测定不同温度条件下RetS感应环境温度对Psa毒力因子的调控作用；通过Phos-tag磷酸化实验和RNA-seq测序揭示RetS感应环境温度调控Psa毒力因子的分子机制。研究结果将对解析溃疡病菌低温致病的作用机理提供理论依据，同时对溃疡病的有效防控具有重要的指导意义。

Bacterial canker of kiwifruit, caused by Pseudomonas syringae pv. actinidiae (Psa), has become a threat to kiwifruit production worldwide. The disease tends to grow and proliferate under low-temperature conditions. Temperature plays an important role in the initial period, the speed of expansion, and the degree of disease severity. However, there are no reports regarding the pathogenic mechanism of Psa under low temperature. In recent studies, it was found that the histidine kinase RetS was related to the pathogenicity of canker bacteria under low temperature conditions by the transcriptome data. This study aims to further analyze the gene retS sequence, protein structure characteristics, and phosphorylation site through bioinformatic methods, and construct the deletion mutant gene, complement mutant of gene retS, phosphate site mutant of protein RetS, and analyze its pathogenicity, growth, temperature adaptability, biofilm, motility, and colonization ability under different temperature conditions. These results will determine the virulence factors of Psa regulated by RetS under different temperature conditions, and in addition confirm the molecular mechanisms of RetS in the regulation of Psa virulence under low temperature conditions by Phos-tag phosphorylation experiment and RNA-seq sequencing. The results of this study will provide a theoretical basis to further analyze the pathogenic mechanism of Psa under low temperature, and provide theoretical management to prevent and control the outbreak of the disease.