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

项目背景：疾病耐受性是寄主植物在被病原体感染的情况下生长和产生公平产量而不表现出严重症状的一种防御策略。氧脂素（含氧脂肪酸）是在许多宿主病原体关系中对感染反应产生（诱导）的第一防御化合物之一。目前存在超过200种氧脂类，它们是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，在特定的宿主病原体关系中，如大豆疫霉（P.sojae）病理系统中，氧脂素可能是新型疾病耐受性的强有力的生化来源。问题陈述：由大豆腐病引起的根茎腐病造成的全球大豆作物损失超过10亿美元。疾病管理战略目前寻求新的持久抗性来源，以防止作物损失。我们之前的研究（Ranatunge et al . 2008）表明，抗性大豆品种可以快速诱导蜡质和亚色胺合成，这是控制大豆假单胞菌感染的成功策略的一部分。然而，在这种病理系统中，氧化脂素在这种或其他成功的宿主防御反应中起什么作用尚不清楚。假设：在大豆- P. sojae病理系统中，氧化脂素在脂肪酸介导的防御反应和疾病耐受性中发挥重要作用，并可能作为该病理系统中疾病耐受性的新生化来源。长期目标：了解大豆P. sojae病理系统中成功的疾病耐受性/抗性机制。短期目标：具体来说，我将在大豆-大豆大豆病系统中研究以下内容：1)植物氧脂素诱导对寄主定植和感染的响应；2)氧脂素在发病过程中的植物保护、抗菌或毒力作用；3)植物和病原体衍生的氧脂素与疾病耐受性或致病性的空间相关性。方法：试验杯接种法将与色谱、脂质成像、振动光谱和质谱技术一起用于测定易感染和耐感染大豆品种的氧化脂素反应。意义：本研究将提供新的发现，并提高我们对大豆P. sojae病理系统中氧脂素诱导/代谢在疾病耐受性或发病机制中的认识。这些结果可用于开发新的生化耐受性来源，以提高大豆对根茎腐病的先天抗性。提高大豆对大豆疫病的耐受性将是一项有效的长期作物保护策略，有助于减少全球大豆疫病造成的数十亿美元的产量损失。

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.