Oxylipins:novel sources of soybean disease tolerance against Phytophthora sojae infection

项目背景：疾病耐受性是一种防御策略，寄主植物在受到病原体感染的情况下生长和生产公平的产量，而不表现出严重的症状。氧化脂肪(含氧脂肪酸)是在许多宿主病原体关系中，对感染作出反应而产生(诱导)的第一种防御化合物。现存200多种氧脂，它们构成植物防御策略的一部分，作为信号分子诱导防御反应，或直接作为抗菌化合物发挥作用。这些作用模式表明，在大豆疫霉(P.sojae)等特定寄主关系中，氧磷脂可能是新的抗病能力的有效生化来源。*问题陈述：大豆疫霉引起的根和茎腐烂导致全球大豆作物损失超过10亿美元。疾病管理战略目前正在寻找新的持久抗性来源，以防止作物损失。我们之前的研究(Ranatunge Et Al 2008)表明，耐性大豆品种迅速诱导蜡质和大豆黄腐素合成是控制大豆疫霉侵染的成功策略的一部分。然而，目前还不清楚氧化脂质在这个或其他成功的宿主防御反应中扮演了什么角色。*假说：在大豆疫霉病原系统中，氧磷脂在脂肪酸介导的防御反应和抗病中起着重要作用，并具有潜在的作为新的抗病生化来源的潜在用途。长期目标：了解大豆疫霉病原系统成功耐病/抗病的机制。短期目标：具体地说，我将在大豆疫霉病原系统中研究以下内容：1)植物抗氧化脂诱导对寄主侵染和侵染的反应；2)在发病过程中，抗氧化脂的植物保护、抗菌或致病作用；3)植物和病原菌来源的氧化脂质与耐病或致病性的空间相关性。*方法：采用试杯接种方法，结合层析、脂类成像、振动光谱和质谱学技术，测定大豆疫霉侵染后大豆品种对氧化脂质的反应。*意义：本研究将提供新的发现，提高我们对大豆氧化脂质诱导/代谢在大豆-大豆疫霉致病系统中耐病或致病机制的理解。这些结果可用于开发新的生物化学耐性来源，以提高大豆对大豆疫霉根腐病和茎腐病的天然抗性。提高大豆对大豆疫霉的耐受性将是一种有效的长期作物保护战略，有助于减少因大豆疫霉感染而造成的全球大豆产量损失数十亿美元。

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.**