Plants can induce a unique form of systemic resistance termed systemic acquired resistance (SAR), which functions even better than the acquired immunity of vertebrates because it protects against secondary infection from a broad-spectrum of pathogens. During SAR, a mobile signal(s) generated at the site of primary infection, moves systemically presumably through the phloem to prepare the non-infected portions of the plant against future infections. However, our knowledge of the intercellular transport of the SAR signal(s) is limited. The investigators have identified several key components of the mobile SAR signal(s) and associated them with specific biochemical signaling pathways responsible for inducing SAR. In this project the investigators will study how these signals are transported during SAR and identify the components involved in their transport.
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 facilitate the use of SAR in protecting agriculturally important plants against a wide range of pathogens. This project will 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. Metabolome 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. The knowledge gained through this project will facilitate the use of SAR in developing long lasting and broad-spectrum crop protection strategies. Regulation of metabolite transport is fundamental to all aspects of plant development because it affects the movement of metabolites and signaling molecules between cells and across organs. Therefore, this project would provide conceptual advances relevant to both health and disease physiologies of plants. The significant similarity of symplasmic structures in animals and plants extends the relevance of this work to animal physiology. This project will involve training of undergraduate students from local colleges, which in turn will facilitate a partnership between the University of Kentucky and primarily minority and/or underrepresented student-serving institutions in the state. The investigators' involvement in STEM education will generate research opportunities for middle/high school students in the state. This project will also involve the training of graduate students and postdoctoral researchers. Data generated from this project will be available via a project-specific website as well as traditional routes including publications and presentations.
