由稻瘟病菌引起的稻瘟病是严重危害水稻安全生产的真菌性病害。水稻与稻瘟病菌的相互作用符合“基因对基因”模式。水稻的23个抗病基因和稻瘟病菌的9个无毒基因已经被克隆。在已经确定的水稻R蛋白中，Pia与稻瘟病菌的效应因子Avr-Pia和Avr1-CO39存在直接的相互作用。RGA5-A作为Pia (RGA4/RGA5-A)的一个重要组分，通过其C端RATX1结构域与Avr-Pia和Avr1-CO39直接结合，但其结合机制尚未明确。申请人拟通过解析RGA5-A的RATX1结构域、与之互作的稻瘟病菌效应因子蛋白以及上述蛋白复合物的三维结构，确定参与识别的关键残基，以期深入了解RGA5-A识别效应因子的结构基础。这些研究结果将为进一步分析具有RATX1结构域的R蛋白如何识别效应因子并引防卫反应提供依据，并为持久抗病性的作物选育提供新的材料和理论基础。

The rice blast disease caused by Magnaporthe oryzae is one of the most serious fungal diseases worldwide. The specific interaction between avirulence (Avr) genes in M. oryzae and resistance (R) genes in rice can be well explained by the gene-for-gene system. Up to now, 23 rice resistance genes to M. oryzae have been cloned, while only five corresponding Avr genes have been identified. Among these R proteins, Pia has been confirmed to directly interact with effortor protein Avr-Pia and Avr1-CO39 from M. oryzae. RGA5-A, an important component of the Pia resistance-protein complex (RGA4/RGA5-A) in rice, interacts with Avr-Pia and Avr1-CO39 via its effector-interaction domain RGA5-A_S(RATX1). However, due to limited biochemical and biophysical studies, the molecular mechanism by which RGA5 recognizes AVR-Pia or Avr1-CO39 remains unclear. To better understand the interactions, we will determine the structures of these proteins and protein complexes. The proposed project will provide new insights into the interaction between R proteins and effectors and new materials for the disease-resistance breeding.