DISSERTATION RESEARCH: Pathogen Interaction in a Forest Ecosystem: Sympatric Phytophthora Pathogens in the 'Sudden Oak death' epidemic

University Of California-Berkeley, Berkeley CA

Investigators

Abstract

On the west coast of the United States, an invasive oomycete pathogen, Phytophthora ramorum, is currently causing high infection and mortality rates in ecologically important forest environments. One lethal disease caused by this pathogen has been dubbed "sudden oak death". P. ramorum shares host-plant and geographic ranges with two other recently described pathogenic Phytophthora species. Concurrent infection of some hosts and similar distributions of these pathogens suggest they may interact with the more virulent P. ramorum to enhance or inhibit infection. Such interactions are potentially important for understanding and modeling the U.S. "sudden oak death" epidemic. The goal of this project is to test whether these three pathogens compete in leaf infections of bay laurel - a host tree significant for disease transmission that is common to all three species. The experimental design incorporates effects of variability in the host, pathogen and environment on interaction outcome. This variability is often excluded in pathogen competition studies. Thus, results will not only elucidate effects on P. ramorum disease, but more broadly, will assist in exploring multi-species infection dynamics in other host/pathogen systems. Study findings will be widely disseminated and contribute to interdisciplinary collaborations for disease modeling, disease management and community outreach.