PhD Candidate University of Toronto Toronto, Ontario, Canada
Body of Abstract: Plants cannot see danger, instead they rely on a large network of cell surface receptors to recognize environmental signals and integrate them into adaptive responses. Many extracellular signals are perceived by a subset of receptors called leucine-rich repeat receptor-like kinases (LRR-RLKs) of which there are approximately 225 members present in Arabidopsis. These LRR-RLKs have been shown to have important roles in both plant growth and immunity, but the functions of many of these receptors remain unknown. To assign function to orphan receptors we used a combination of expression and protein-protein interaction network analysis to identify candidate receptors for immune regulatory signals. This analysis showed that the SRF family of LRR-RLKs are expressed in response to infection with an avirulent bacterial pathogen and have network characteristics indicative of possible immune function. Phenotyping analysis has shown that some srf mutants are more susceptible to bacterial infection and have altered defense gene expression following treatment with immune eliciting compounds derived from damaged plant cell wall. We have demonstrated that the srf6 mutant is unable to recognize TGA (trigalacturonic acid) and therefore fails to mount a defense response, while overexpression lines show the opposite phenotype. These findings point towards the SRF receptors having a role in plant cell wall damage sensing pathway.