Fine Mapping Of A QTL, QBisr5b, Resistant To Bacterial Leaf Streak In Rice(Oryza Sativa L.)

Bacterial leaf streak (BLS) is a familiar epidemic disease in rice in South China. In recent years, it has become a main disease by degrees and caused serious yield losses in rice. So it is desirable to exploit the rice germplasm possessing disease resistance against bacterial leaf streak to improve the disease resistance of present rice hybrids.Based on the research of pioneers, my study worked on the fine mapping of a QTL which controls the resistance of BLS. The main results are summarized as follows:1 Using Acc8558 as a recurrent parent, H359 as a donor parent, A NIL ( H359R) with resistant gene was developed. Analysis of graphical genotype showed that the regions with 3 QTLs from Acc8558 had been injected into H359R and were located on chromosome 3 and 5. The result coincided with WuWeiren's and Tang's primary mapping and proved the authenticity of these QTLs.2 A total of 17 SSR markers in the target region were adopted to analyze its polymorphism with BSA. The result showed that in the polymorphic markers, 3 pair of primers, RM430, RM173 and RM178 located in the long arm of chromosome 5. The region including these 3 markers coincided with WuWeien's and Tang's. So we can make sure that the target region had the presence of the QTL.3 Surrounding the target region of RM430, RM173 and RM178, 4 SSR markers were selected. These SSRs are codominant, good reproducible and stable. Using these primers, 420 individuals of F2 population of H359xH359R were analyzed. Amolecular map was constructed by using Mapmaker program with markers as follows, RM430, RM173, RM178 and RM26. The total length was 23.3 cM. By means of interval analysis, QTL mapping and genetic effect analysis of BSL were performed, The QTL qBlsrSb was 3.0 cM away from RM430 on the linkage map and explained 4.64% of the phenotypic variation.