Fine Mapping Of A Blast Resistance Gene In Japonica Two-line Male Sterile Line7001S And Related Candidate Genes Analysis

Rice blast caused by Magnaporthe grisea is a worldwide rice disease. Its incidence area and harmful levels is the first of the three major diseases of rice, causing serious losses to China and the world rice production each year. Use of resistant cultivars is the most economical, effective and safe among ways of prevention. However, resistant varieties with a single resistance gene will reduce or even completely lose blast resistance and spectrum with the evolution of pathogens and the advantage of physiological changes during long-term cultivation. Therefore, it is crucial to identify and exploit resistance resources, and to isolate and clone resistance genes. Utilizing these new resistance genes to breed new resistant varieties becomes the eternal project of modern rice blast resistance breeding.The7001S derived from Nongken58S/917is a japonica type photosensitive genie male sterile.The varieties, grown in Anhui, Yunnan. Guizhou, Sichuan, Hubei and other rice blaslre-development zone, is an ideal material owing to high resistance and wide resistance spectrum. Genetic analysis showed that the resistence of7001S to the rice blast is controlled by single-gene loci, and the rice blast resistance gene was located on the terminal long arm of chromosome11. This research aimed at fine mapping and candidate gene analysis for blast resistance gene Pi-ja.The concrete results are as follows:1. D1and D2two F2populations were applied to fine mapping of the Pi-ja gene.In the D1population,the Pi-ja gene was finely mapped at the end of the long arm on chromosome11between P21-241.5and RM27322, with genetic distances of0.13cM and0.13cM respectively, and the physical distance of this interval is310kb, in which three markers, I7-1,N22-550and N22-3600.co-segregated with this gene.In the D2population, the Pi-ja gene was delimited to a0.58cM region flanked by1-15379and S10-57, in which three markers, I9-1,N22-550and N22-3600, co-segregated with it.2. Construct a high-resolution map and an electronieally physical map spanning the target region of the Pi-ja gene.3.Through identification of candidate gene markers as well as sequencing of candidate genes, candidate genes were narrowed from six genes to just two genes, which arc LOC_Os11g45980and LOC_Os11g46200.4. Candidate gene LOC_Os11g45980encoded NBS-LRR disease resistance protein. LOC_Os11g45980has four exons with full length of5255bp and991ami no acids in resistant parent700IS while this gene has only two exons with full length of5272bp and1133amino acid in the susceptible parent80-4B. Candidate gene LOC_Os11g46200encoding LRR resistance protein contained three exons with full length of3378bp and1125amino acids. Protein structure prediction of LOC_Os11g46200shows that it contains an ATP kinase binding sites and a leucine-rich repeat sequences domain.