KSEF RDE: Understanding the Interrelationships between the Various Chemical Inducers of Plant Systemic Immunity

Constant challenges by potentially pathogenic microorganisms have resulted in the evolution of multiple modes of defenses in plants. Active defense mechanisms include the production of antimicrobial compounds, cell wall reinforcement via the synthesis of lignin and callose, and the specific induction of elaborate defense signaling pathways. Of these, systemic acquired resistance (SAR) is one of the most desirable forms of robust and broad-spectrum resistance that immunizes the systemic parts of plants against secondary pathogens. SAR is induced when primary infection induces the generation of a mobile signal, which then translocates to the systemic portions of the plant. SAR induction is often associated with the accumulation of the phytohormone salicylic acid (SA). Recent studies focused on SAR have resulted in the identification of several, seemingly chemically unrelated, mobile inducers of SAR. These include the phosphorylated sugar derivative glycerol-3-phosphate, a dicarboxylic acid azelaic acid, and a non-protein amino acid pipecolic acid. This proposal aims to use molecular, genetic and biochemical tools to determine the interrelationship between these different chemicals and the possible overlap in the resultant signaling events. In the long term, chemical signals that do not involve diversion of carbon, nitrogen, and energy away from the plant's primary metabolic pathways will be used in crop improvement as they are less likely to impact yield negatively.