Prediction and characterization of WY-domain effectors in downy mildews
K. WOOD (1), L. Derevnina (2), S. Reyes Chin Wo (3), J. Gil (3), J. Wong (4), R. Michelmore (3) (1) UC Davis, U.S.A.; (2) The Sainsbury Lab, United Kingdom; (3) UC Davis, U.S.A.; (4) Bayer, Belgium

Plant pathogens use a diverse arsenal of effector proteins to suppress the host immune system and promote infection. Identification of effectors in pathogen genomes is of major interest for understanding the mechanisms of pathogenesis, for monitoring field pathogen populations, and for breeding disease resistant plants. Using comparative genomics and bioinformatics, we have identified candidate effectors from several economically important downy mildew species by searching for the WY domain, a conserved structural element found in Phytophthora effectors that has been implicated in their immune-suppressing function. Searching for the WY-domain uncovered additional effector candidates that were missed by searching for the RXLR domain alone. There is significant variation among the WY effector candidates in both sequence and domain architecture. The candidate effectors show several characteristics of pathogen effectors, including an N-terminal secretion signal, lineage specificity, and evidence of gene duplication and gene family expansion. Unexpectedly, a minority of WY effectors contained the canonical N-terminal RXLR motif, which is a conserved feature in Phytophthora effectors. This suggests an evolutionary divergence in effector sequence between genera that has important implications for effector prediction in oomycetes outside the genus Phytophthora.

Abstract Number: P11-385
Session Type: Poster