Participant Support: Examining the Importance of Dynamic Trafficking in Systemic Acquired Resistance

Systemic acquired resistance (SAR) is a highly desirable form of resistance that protects plants against a broad-spectrum of pathogens. During SAR, a mobile signal(s) is generated at the site of primary infection, which moves systemically to trigger defense in the non-infected portions of the plant. Current understanding is limited to the knowledge of various molecular components essential for this mode of defense. Although the phloem is the presumed site of signal translocation, little has been done to determine the mechanism of intercellular transport of the SAR inducing signal(s). Potentially, the identification of SAR signal(s) and the knowledge of their dynamic movement could greatly facilitate the use of SAR in protecting agriculturally important plants against a wide range of pathogens. This proposal aims to examine the role of dynamic gating (opening and closing) of the plasmodesmata (PD) in SAR induction and assess its relationship to some essential mobile SAR inducers. PD gating will be assessed using dye-loading assays during the time frame of SAR signal generation and movement. Molecular and genetic tools will be used to alter PD gating within this time frame and assess the effect on SAR. Metablome analysis of petiole exudates from plants defective in both SAR and PD gating will be carried out to determine levels of known SAR inducers and to identify other unknown SAR regulators. Molecular, genetic, and biochemical analyses will be used to characterize the relationship between PD and various SAR related components.