水稻是我国最重要的粮食作物，褐飞虱是水稻的专一性害虫。在长期的协同进化过程中，水稻形成了抗性基因，而褐飞虱在抗性基因的选择压力下可发生致害性变异，形成能克服原来抗性水稻的新生物型。在克隆抗褐飞虱基因基础上，挖掘其新的等位变异，阐明其进化规律及抗性分子机理，解析等位变异与褐飞虱致害性变异的分子互作关系，将为应对褐飞虱致害性变异提供支撑。本课题在克隆抗褐飞虱基因BPH9的基础上，将进一步明确12号染色体上8个抗褐飞虱基因的等位关系；并以全基因组测序的水稻资源为材料，通过关联分析发掘BPH9新的等位变异，解析BPH9的起源与进化，明确BPH9等位变异抗褐飞虱不同生物型的分子基础。结合BPH9重要互作蛋白及抗虫分子机理研究，进行BPH9功能结构域分析及结构域重排，明确重点结构域或功能氨基酸在抗褐飞虱中的作用，继而进行BPH9人工等位变异体设计以应对褐飞虱致害性变异，为实现褐飞虱可持续防控提供支撑。

Brown planthopper (BPH), Nilaparvata lugens Stål, is the most devastating insect pest of rice (Oryza sativa L.). In the course of co-evolution, rice has developed complex and specific systems of resistance against BPH. In parallel, biotypes of BPH have evolved in virulence enabling them to overcome rice resistance. 30 BPH-resistance genes have been genetically defined in rice; most of these genes appear to be clustered in certain chromosomes. The molecular relationship between most clustered BPH genes is not clear. We have cloned a BPH-resistance gene, BPH9, on rice chromosome 12L. BPH9, BPH2/26 and BPH18 clustered on chromosome 12L are actually alleles of the same gene. BPH9 encodes a rare type of the CC-NBS-LRR-type NLR protein and induces programmed cell death in rice upon overexpression. In this study, we will further explore natural allelic variation of BPH9 in rice germplasms from 3000 Rice Genomes Project (IRRI) with genome-wide association studies (GWAS). We will detect the effects of allelic diversity in BPH9 on BPH population and mechanism for virulence variation in this insect, and elucidate the genetic basis of BPH9 allelic diversity to combat BPH variation. Further artificial shuffling within BPH9 allelic diversity will allow breeding to be tailored to control new biotypes of BPH. The results will contribute to development of durable resistant rice variety for sustaining control of BPH in rice.