Role of phosphatidic acid and AGC kinases in plant/microbe interactions and under stress

内生真菌Priformospora inda是一种可培养的担子菌，在包括拟南芥在内的许多植物的根部定植，促进其生长、生物量和种子产量。基于对拟南芥不反应的突变体的遗传筛选，我们确定了促进生长所需的激酶级联反应。该真菌刺激根细胞中磷脂酸(PA)的合成，从而激活3-磷酸肌醇依赖的蛋白激酶1(PDK1)，然后是氧化信号INDUCIBLE1(OXI1)和丝裂原激活的蛋白激酶3和-6。此外，生长反应还需要与OXI1同源的AGC2-2。在这项建议中，将分析这一途径在有益(水稻)和病原(甘蓝)植物/微生物相互作用、诱导系统抗性和非生物胁迫反应(干旱、盐、冷)中的作用。将在生化和分子水平上分析在PA合成或这一途径的激酶方面受损的微生物和压力暴露突变体的适合性。比较分析将确定PA-PDK1-OXI1/AGC2-2信号通路在植物/微生物相互作用和非生物胁迫下的作用。

The endophytic fungus Piriformospora indica, a cultivable basidiomycete of Sebacinales, colonizes the roots of many plant species including Arabidopsis and promotes their growth, biomass and seed production. Based on a genetic screen for Arabidopsis mutants which do not respond to P. indica, we identified a kinase cascade that is required for growth promotion. The fungus stimulates the synthesis of phosphatidic acid (PA) in root cells which activates 3-PHOSPHOINOSITIDE-DEPENDENT PROTEIN KINASE1 (PDK1) followed by OXIDATIVE SIGNAL INDUCIBLE1 (OXI1) and the MITOGEN-ACTIVATED PROTEIN KINASES 3 and -6. Furthermore, AGC2-2, a homolog of OXI1, is required for the growth response. In this proposal, the role of this pathway for beneficial (P. indica) and pathogenic (A. brassica) plant/microbe interactions, induced systemic resistance and abiotic stress responses (drought, salt, cold) will be analysed. The fitness of microbe- and stress-exposed mutants impaired in PA synthesis or kinases of this pathway will be analysed at biochemical and molecular levels. The comparative analysis will define the role of the PA-PDK1- OXI1/AGC2-2 signalling pathway in plant/microbe interactions and under abiotic stress.