一个水稻氢过氧化物裂解酶（HPL）基因突变体在植物抗病、虫防御反应中的功能研究

The hydroperoxide lyase (HPL) genes in lipoxygenases (LOX) oxylipin branch pathways are considered to function in response to the plant biotic stresses.But little is known about its molecular mechanisms and signaling regulation. Starting with a rice "lesion mimic" mutant, which has enhanced resistence to rice bacterial blight Xanthomonas oryzae pv. oryzae (Xoo) and was identified the target gene as a HPL gene by map-based cloning, we sought to investigate the regulation mechanism and potential function of HPL gene in plant defense responses to the bacterial pathogen and piercing-sucking pests. The over-expression and RNAi knock down transgenic rice would be constructed and analyzed for their phenotypes and responses to the bacterial and pests challenges, and we try to elucidate the molecular functions of HPL gene in the defense response and it's relationship with other defense hormones such as jasmonate acid (JA) and ethylene (ET).

植物中脂氧合酶代谢途径（LOX途径）中分支代谢氢过氧化物裂解酶（HPL）基因在植物抗病、虫防御反应中发挥着重要的功能，但是目前对其作用的分子机制和调控知之甚少。本项目从一个由于HPL基因突变导致"类病斑"和抗病性增强表型的水稻突变体hpl出发，利用图位克隆方法分离突变体基因，并转基因互补验证了表型，在此基础上综合正、反向遗传学的方法，对HPL基因的突变体、超表达及RNAi转基因水稻的表型及其在病原菌和刺吸式害虫侵染诱导下的应激反应进行研究，解析HPL基因在植物的抗病、虫防御反应中的功能，及其与JA和ET等其他植物抗病、虫防御激素信号传导途径的关系。

构建了HPL3 RNAi转基因植物，进一步阐明突变体hpl表现出来的“类病斑”表型是由HPL3基因的突变引起。并构建了Coi1RNAi 和Myc2 超表达转基因植株，与hpl突变体杂交进一步去研究HPL与JA信号传导途径之间的关系。对突变体及转基因植物的底物酶活性，产物含量，产物补给喷施，激素浓度以及基因表达分析阐明了hpl突变体在抗病和抗虫防御中作用分子机制。结果揭示了hpl突变体在抗病防御作用中的分子机制是由于JA信号传导途径被强烈诱导激活造成，并第一次给出了这两个氧脂代谢分支途径之间存在crosstalk的实验证据。揭示了SA和JA信号传导调控在hpl突变体对刺吸式昆虫BPH的抗性中同样起到调控功能。这加深了我们对水稻中抗病、虫防御分子机制的理解，并为进一步水稻的抗病、虫品种的分子改良提供新的思路和理论指导。