Grant: Discovery Grants Program - Individual

Project Context: Disease tolerance is a defense strategy used by host plants to grow and produce equitable yield without displaying severe symptoms despite being infected by a pathogen. Oxylipins (oxygenated fatty acids) are among the first defense compounds produced (induced) in response to infection in a number of host pathogen relationships. There are over 200 oxylipins in existence that form part of the plant defense strategy, serving as signal molecules to induce defense responses, or function directly as antimicrobial compounds. These mode of actions indicate oxylipins could be potent biochemical sources of novel disease tolerance in specific host pathogen relationships such as the soybean Phytophthora sojae (P.sojae) pathosystem. Problem statement: Root and stem rot caused by P.sojae account for over a billion dollars in soybean crop loss worldwide. Disease management strategy currently seeks new sources of durable resistance to protect against crop losses. Previous research by us (Ranatunge et al 2008), demonstrated that tolerant soybean cultivars rapidly induced wax and suberin synthesis as part of a successful strategy to control P.sojae infection. However, it is unknown what role oxylipins play in this or other successful host defense response in this pathosystem. Hypothesis: Oxylipins play a significant role in fatty acid mediated defense response and disease tolerance in the soybean- P. sojae pathosystem, and have potential uses as novel biochemical sources of disease tolerance in this pathosystem. Long term objectives: To understand the mechanisms underlying successful disease tolerance/resistance in the soybean- P. sojae pathosystem. Short term objectives: Specifically, I will study the following in the soybean- P. sojae pathosystem:1) plant oxylipin induction in response to host colonization and infection 2) the phytoprotective, antimicrobial or virulence effects of oxylipins during pathogenesis, 3) spatial relevance of plant and pathogen derived oxylipins to disease tolerance or pathogenicity. Methodology: Test cup inoculation methods will be used along with chromatographic, lipid imaging, vibrational spectroscopic and mass spectrometric techniques to determine oxylipin response following P.sojae infection in susceptible and tolerant soybean cultivars. Significance: The proposed research will provide novel discoveries and improve our understanding concerning oxylipin induction/metabolism in disease tolerance or pathogenesis in the soybean- P. sojae pathosystem. The outcome of these findings could be used to develop novel biochemical sources of tolerance to improve the innate resistance of soybeans to root and stem rot caused by P. sojae. Development of increased P. sojae tolerance in soybeans will be an effective long term crop protection strategy beneficial in reducing billions of dollars in soybean yield losses globally to P. sojae infection.