MPK4甲基化调控水杨酸信号介导的拟南芥对齐整小核菌菌株SC64的抗性机制

为提升齐整小核菌Sclerotium rolfsii菌株SC64作为生物除草剂的应用潜力,解析植物对其的防御机制,通过比较6种生态型拟南芥Arabidopsis thaliana(Col-0、Ms-0、Gr-1、Se-0、Tu-0和Wa-1)被菌株SC64侵染后病理特征、茎秆木质素水平以及抗病相关基因表达的差异,筛选出抗性最高和抗性最弱的典型生态型拟南芥,通过施加0.1 mmol/L外源水杨酸来验证其在拟南芥防御菌株SC64侵染过程中对木质素代谢及病理的调节作用,并比较分析6种生态型拟南芥水杨酸上游调控通路基因MPK4启动子区域的甲基化差异。结果显示,6种生态拟南芥中Col-0的木质素化程度最高,被菌株SC64侵染时木质素代谢通路基因CAD4和PAL3表达上调最显著,与其抗病能力最强相吻合,而Ms-0的病理表型和抗病能力最弱。外源水杨酸预处理使具典型抗性的生态型拟南芥Col-0受菌株SC64侵染后发病程度加重,木质素化程度减弱,同时木质素代谢通路基因MYB46、LAC17、PAL3和CAD4被菌株SC64侵染后的表达上调程度均显著减弱。另外,6种生态型拟南芥MPK4基因启动子区域CHH...

MPK4 methylation of Arabidopsis thaliana regulates salicylic acid signaling mediated resistance to Sclerotium rolfsii strain SC64

In order to improve the application potential of Sclerotium rolfsii strain SC64 as a bioherbicide, it was necessary to dissect its defense mechanism in plants, and the pathological phenotype, lignification levels and disease response related gene expression differences of six ecotypes of Arabidopsis thaliana (Col-0, Ms-0, Gr-1, Se-0, Tu-0 and Wa-1) infected with strain SC64 were compared. Two A. thaliana typical ecotypes (Col-0 and Ms-0) were selected through pathological phenotype, the lignin metabolism and pathology response during the infection of strain SC64 was then verified with the application of 0.1 mmol/L exogenous salicylic acid, the methylation differences of MPK4 promoters of the upstream regulatory pathway gene of six ecotypes of A. thaliana salicylic acid were also compared ultimately. The results showed that Col-0 had the highest degree of lignification among the six ecotypes of A. thaliana species, and the expression of CAD4 and PAL3 genes was significantly upregulated when infected by the strain SC64. This was consistent with its strongest disease resistance, while the pathological phenotype and disease resistance of Ms-0 were the weakest among the six ecotypes. The pretreatment of exogenous salicylic acid aggravated the incidence and lignification of the bio-resistant A. thaliana after infection by strain SC64, and the upregulation in expression of the lignin metabolism pathway genes MYB46, LAC17, PAL3 and CAD4 was significantly reduced. In addition, the number of CHH methylation sites of the MPK4 promoter of the six ecotypes of A. thaliana were positively correlated with their relative expression and lignin levels, respectively, and were negatively correlated with the relative expression of the EDS1 gene and leaf disease area. The results showed that A. thaliana positively regulated the expression of the MPK4 through the number of CHH methylation sites of promoter, thereby negatively regulating the metabolism of salicylic acid, which further increased the level of lignin metabolism and ultimately enhanced the resistance to the strain SC64.