Comparative Genomics of Temperate and Tropical Downy Mildews
K. FLETCHER (1), L. Derevnina (2), S. Reyes-Chin-Wo (3), L. Bertier (3), A. Kozik (3), R. Michelmore (3) (1) Genome Center, UC Davis, U.S.A.; (2) The Sainsbury Laboratory, United Kingdom; (3) Genome Center, UC Davis, U.S.A.

Downy Mildews (DMs) are a group of biotrophic oomycetes responsible for diseases on a wide variety of dicotyledonous and monocotyledonous plants, including lettuce, tobacco, pearl millet, sorghum & maize. It appears most likely that the biotrophic DMs evolved one or more times from hemibiotrophic Phytophthora-like ancestors, although the molecular basis of obligate biotrophy is unknown at present. Consequentially, the study of DMs at the molecular level is impeded by the lack of axenic culture and the requirement to be cultured with a host plant. An increasing number of DM genomes are being sequenced; presently we are working with the genomes of nine DM species to gain insights into the origin of DMs and the basis of biotrophy. This has indicated that the adaptation to biotrophy may have occurred more than once within the Phytophthora clade. We have identified a set of Core Orthologous Phytophthora Specific proteins/genes (COPS). Comparisons of this data set with the genomes of DMs have identified some COPS absent from the DMs and allow us to infer protein/gene losses that have occurred during the adaptation to biotrophy. As expected, a subset of COPS encoding flagella proteins were not detected in DMs which have lost the motile zoospore stage.

Abstract Number: P11-354
Session Type: Poster