The human population is projected to reach 9.7 billion by 2050. The looming challenge of feeding the rapidly growing population is threatened by crop losses from plant diseases. Phytophthora are filamentous eukaryotic pathogens that cause numerous destructive plant diseases including potato late blight that was responsible for over 1.5 million deaths during the Great Irish Famine and the sudden oak death that has killed millions of forest trees. As a group of pathogens with both historical and current importance, battling Phytophthora diseases is an important mission and a major challenge in agriculture. This project aims to elucidate the molecular mechanisms underlying Phytophthora pathogenesis and, based on this knowledge, develop durable resistance in potato and other important crops. As such, this project will not only provide insight into basic biology of plant-pathogen interactions but also directly benefit US Agriculture. Broader impacts of this project include providing interdisciplinary training to postdoctoral researchers, graduate students and undergraduate students on cutting-edge technologies of genetics, biochemistry and molecular biology. It will also reach out to stakeholders, such as potato growers, by informing them with the latest findings and technologies on developing disease resistance in crops.<br/><br/>This project is funded jointly by NSF and by NIFA/USDA.<br/><br/>Phytophthora employs a large arsenal of virulence proteins, called effectors, to facilitate infection. Directly manipulating plant cellular processes, effectors play an essential role in the arms race with the hosts. An overall understanding of effector functions and the molecular mechanisms underlying their diversification and adaptation is critical to implement durable resistance. This project is based on the exciting discovery that a large number of Phytophthora effectors contain tandem repeats of a conserved structural module, which tolerates a high level of sequence flexibility. Using a combination of genetic, molecular biology, and biochemical approaches, this project will test the hypothesis that this conserved module may serve as a basic building block to enable effector evolution for novel activities and thereby contributing to virulence. Furthermore, plant defense mechanism targeting this conserved module may enable effective resistance against the destructive Phytophthora diseases. The goals of this project are: 1) elucidating the role of this conserved structural module in Phytophthora effector function and evolution; and 2) identifying resistance genes that recognize this conserved structure of Phytophthora effectors from wild potato species. The outcome of this project will make major advancement in the fundamental understanding of Phytophthora diseases. This project is translational because the resistance genes identified from wild potato accessions may be incorporated into elite varieties in order to confer resistance to late blight. These genes could also be used to confer sustainable resistance to a broad variety of Phytophthora species.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.