This research will analyze the sexual cycle of the fungus-like microbe Phytophthora infestans, which is a member of the lower eukaryotic group known as oomycetes. This group includes many species that are extremely important plant pathogens, in which sexual spores commonly serve as the primary inoculum for disease epidemics. The central issue addressed by this project concerns how the expression patterns of genes and proteins needed for sexual development are regulated. A combination of molecular genetic and biochemical strategies will be employed. These will involve analyses of promoter sequences that drive the expression of mating-specific genes; of proteins that regulate the genes by binding to their promoters; and of proteins that are believed to control the translation of messenger RNA into protein by binding to specific RNA transcripts. This work should therefore identify both transcriptional and post-transcriptional regulatory mechanisms that are essential for the formation and/or germination of sexual spores by Phytophthora and its relatives. Such findings will illuminate the biology of this little-understood but economically and environmentally important group of organisms, and help indicate how regulatory mechanisms have evolved in diverse eukaryotes. Proteins that regulate sexual spore development may also serve as targets for new strategies for preventing disease, for example by using inhibitors that block spore formation. Another important objective of this project will be fulfilled through its training of undergraduates, graduate students, and postdoctoral researchers, thereby aiding in the development of a scientific workforce for the country.
