The phosphorylation of cellular targets by protein kinases is used by eukaryotes to transmit developmental and environmental signals to cellular targets. This proposal focuses on the role of protein kinases in the biology of the spores of Phytophthora infestans, the potato late blight pathogen. This species is a member of the group of microbial eukaryotes known as oomycetes. These include many plant and animal pathogens that are current and potential threats to crop production and food security. Prior work by the Judelson laboratory showed that spores require protein kinases to function normally, and identified several kinases expressed specifically during spore formation and germination. Using a combination of molecular and biochemical approaches, the research planned will identify proteins that interact with these kinases, including both regulators of the kinases and proteins phosphorylated by the kinases. The functions of selected kinases and their interactors in the biology of Phytophthora will also be assessed by making mutants. Spores are important to Phytophthora and related species since they are the main structures used to disseminate such pathogens, and since penetration of their plant and animal hosts usually involves specialized structures formed by germinated spores. Understanding the biology of spores should therefore lead to effective and environmentally safe strategies for preventing disease. This research will also be synergistic with existing NSF initiatives in Phytophthora genomics and biology, and contribute to student training at a Postsecondary Minority Institution.