稻瘟菌单氧酶Acp1抑制水稻抗稻瘟病的分子机制

稻瘟菌（Magnaporthe oryzae）是危害水稻安全生产的最主要病害之一，它与寄主长期博弈中进化出多种毒性因子来抑制植物的抗病反应。稻瘟菌单氧酶基因作为毒性因子对于稻瘟菌致病力至关重要。本研究对不同稻瘟菌小种测序发现，编码该基因中特定碱基的突变，造成不同小种间存在编码两个具有相同ABM结构域的蛋白 (Abm和Acp1)。Abm已被报道参与羟基化植物茉莉酸 (JA) 进而抑制植物抗病反应，而Acp1的生化功能还未明确。本研究初步发现Acp1与Abm不同，可以结合血红素 (Heme) 而不结合JA，并抑制水稻ROS反应的发生。基于此，本项目拟解析Acp1的晶体结构，分析结构特征，并结合生化和体内遗传实验明确其生化功能，阐明Acp1与Abm功能差异的结构机制。本项目将阐明单氧酶Acp1在稻瘟菌致病过程中发挥作用的分子机理以及在稻瘟菌中变异的进化机制，并为绿色农药设计提供重要的结构基础。

Magnaporthe oryzae is one of the most important diseases that threats the safety of rice production. During the long-term race between rice blast and its host, fungus have evolved diversity virulence factors to suppress the plant resistance. The monooxygenase gene as a virulence factor plays a vital role in the pathogenicity of M. oryzae. It is found by the genome sequencing of different M. oryzae races that the mutation in the gene encoding monooxygenase results in the expression of two proteins (Acp1 and Abm) containing the ABM domain. Abm has been reported in the hydroxylation of jasmonic acid in plants to inhibit plant resistance, while the biochemical mechanism of Acp1 remains elusive. Here, we find that Acp1 protein different from Abm can bind Heme but not JA, and inhibit the plant ROS reaction. Based on that, we will determine the crystal structure of Acp1, analyze the structural features with biochemical and genetic assays in order to verify its biochemical functions, and clarify the structural mechanism of the functional difference between Acp1 and Abm. Taken together, this study will clarify the molecular mechanism of the fungal monooxygenase Acp1 involved in the pathogenesis of M. oryzae and also provide an important structural basis for the green fungicide design.