*** 9513808 Dean Magnaporthe grisea causes rice blast, a devastating disease of rice. Dr. Dean is interested in a specialized developmental process required by this fungus for successful infection of its host. Infection is initiated by the formation of a specialized infection cell, the appressorium. The induction of this uniquely organized cell is dependent on specific environmental cues. The goal of Dr. Dean's research is to understand how the fungus recognizes these cues, relays the information within the cell to initiate appressorium formation as well as the biochemical machinery that is associated with appressorium development and function. Results from these investigations will not only provide fundamental information but will have practical relevance. Dissection of the genetic and biochemical pathways central to infection related morphogenesis will identify new targets for intervention and may lead to the development of rational mechanism based control measures for M. grisea and potentially other fungal pathogens. Previous research identified a number of interesting developmental mutants and showed that a cAMP mediated signal transduction pathway is essential for appressorium formation and pathogenicity. Transformants lacking the gene encoding the catalytic subunit of protein kinase A (cpkA), the principle source of intracellular cAMP, are unable to form appressorium on rice and are nonpathogenic. To further advance our knowledge of intracellular communication and identify other key elements regulating the induction and development of appressorium formation the following experimental objectives are proposed: 1) Isolation and characterization of genes required for appressorium formation, including DNA complementation of mutant loci and identification of transcriptionally regulated genes, 2) Identification and characterization of cellular signaling components mediating the induction of appressorium formation, including G-proteins and other proteins specifically phosphorylated during infection related morphogenesis. ***
