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

• Applicant: Professor Dr. Ralf Oelmüller
• Subject Area: Plant Physiology
• Term: from 2011 to 2014
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 210134337

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.

• DFG Programme: Research Grants