KSEF:Characterization of Signaling Pathway(s) Required for Resistance to Viral and Oomycete Pathogens

Resistance (R)-gene-mediated pathways are triggered as a result of a specific interaction between the host-derived R- and the pathogen-derived avirulence-gene products. Even though initial recognition process leading to an incompatible response is unique between a host and its pathogen, many of the R-gene-mediated pathways are known to share common downstream signals. However, many structurally similar or allelic R-genes also mediate pathways that differ in their requirement for downstream signals. The allelic resistance genes HRT and RPP8 confer resistance to the viral pathogen turnip crinkle virus (TCY) and the oomycete pathogen Peronospora parasitica in a salicylic acid (SA)-dependent and SA-independent manner, respectively. Interestingly, the TCV resistant host, Di-17 also confers resistance to P. parasitica in a SA-independent manner and the R-gene specifying this resistance is unlinked to RPP8. To understand the molecular basis of SA-dependent and SA-independent pathways, we have isolated TCV resistant mutants in a susceptible background and oomycete susceptible mutant in a Di-17 resistant background. Further characterization of these mutants is proposed. The proposed work will not only allow us to understand fundamental components of virus-host and oomycete-host pathogenesis but may also help us gain insight into signaling events that are required for activation of distinct downstream signaling pathways triggered by the allelic R-genes.