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Molecular interactions that influence virulence contributions of the IPI-O family of Phytophthora infestans effectors.

Sidrat Abdullah: University of Wisconsin

<div><em>Phytophthora infestans</em>, causal agent of potato late blight<em>,</em> is a destructive pathogen that is a frequently recurring problem worldwide. Several resistance genes exist in potato to counter against this pathogen, but the majority has been overcome after introgression into popular potato varieties. The <em>RB</em> gene, derived from <em>Solanum bulbocastanum</em>, has effector recognition specificity to members of the IPI-O family. Recognition of the IPI-O1 allele by <em>RB</em> elicits a hypersensitive resistance response while IPI-O4 can suppress this response. We have carried out several experiments to determine the virulence contributions of IPI-O1 and IPI-O4 during infection, and to identify host proteins involved in IPI-O recognition/suppression using co-immunoprecipitation and yeast two-hybrid. Our results indicate that both IPI-O1 and IPI-O4 contribute to <em>P. infestans</em> virulence, but their impact is influenced by the pathogen genotype. Protein interaction studies have identified both cytosolic- and membrane-localized host proteins that interact with IPI-O and will help to elucidate the function of these effectors in pathogen virulence. Together, we hope that our understanding of the function of the ubiquitous IPI-O effector will assist us in identifying or developing improved host resistance genes in potato.</div>