Molecular Mapping Of A New Resistance Gene To Bacterial Blight Of Rice

Rice is one of the most important cereal crops. Bacterial blight of rice, which is a vascular bundle disease caused by Xanthomonas oryzae pv. oryzae (Xoo), is one of the most serious diseases of rice worldwide, and leads to the yield of rice reduced greatly. And, using of chemicals to prevent the disease would cause some serious influence in our environment, also the result is not very effective. So, seeking and using new bacterial blight resistance genes have become more and more important. Now, there were 30 relevant resistance genes found and reported, including 6 had been cloned. But, for the reason of kinds of bacteria and variation, a new resistance gene with high resistance and broad-spectrum is still the hot spot researchers interested in.Here we use the offspring of Y73 which is a asymmetric somatic cell hybrid from Oryza meyeriana and rice as the supplier of the resistance gene. Then we got a Y73/IR24 F2 population by hybrid. And, use the SSR molecular marker technique to map the target gene, which is a important base for the high-resolution mapping and gene cloning. The main research results as followed:(1) We founded a Y73/ IR24 population(including 76 individuals). Identified the resistance representation of individuals by Leaf-cutting method, and the ratio between resistance and sensitivity was 1:3, also the F1 was sensitive. So, we think the main gene which is has important influence in the resistance representation of rice is a stealth gene.(2) Using the DNA from both parents (Y73 and IR24) as the sample, screening 400 SSR primers by SSR-PCR and PAGE, we found 226 polymorphous primes which could be used as molecular markers, distributed in the 12 chromosomes of rice averagely.(3) Establish two DNA pools of resistance and sensitivity separately by selecting 8 different individuals from F2 population, and screen 226 pairs of polymorphism SSR primer using the DNA pools as samples, then found three primers(RM6547, RM1339, RM6292),which all are distributed in the long-arm end of chromosome 1, this mean these 3 markers may be linked with target gene. Also, using the DNA of all F2 individuals as samples, acquired band data of 3 markers by SSR-PCR and PAGE, calculated with the resistance phenotype. We found all 3 markers are linked with the target gene, and RM6547 is the most adjacent, the distance is 22.8 cM.(4) For a better result, we still screened more 98 possible SSR markers in the long-arm end of Chromosome 1. Finally we get a SSR marker RM6405. The distance between RM6405 and target gene is 15.9cM.