Fine Mapping Of QSTV-11b Resistant To Rice Stripe Disease

Rice stripe disease, a kind of viral diseases of rice, is transmitted by the small brown planthopper, Laodelphax striatellus Fallen and mainly occurs in temperate and subtropics zones of East Asia.Rice stripe disease first occurred in Southern Jiangsu in 1963 and it spread all the rice region in China.In 1980s and 1990s, rice stripe disease is not so serious, but the disease is rising in recent years in China, and it had caused a great loss of rice production. With the severe occuurence of the disease, some susceptible plants could also be found in resistant varieties.At present, the most of resistant rice varieties mainly carry the resistant gene Stv-bi which comes from indica rice variety Modan.However, varieties with a single resistance gene may lose their resistance if a new virus strain can overcome the resistance of Stv-bi, it is necessary to find new genes which are resistant to RSV.Wu,et al used F2 lines derived from a cross between the susceptible japonica variety Balilla and the resistant indica variety Dular to assay the resistant loci, and two loci were detected which were both on chromosome 11 with the name of qSTV-11b and qSTV-11c respectively. And then Wu continued to use F3 and BC1F1 population to locate the two loci precisely.At last, qSTV-11b was located in the interval of RM1355～STS11-31 and STS11-19～RM5349 respectively,and the physical distance is 269.6Kb and 440.1Kb.The fine mapping of qSTV-11b was carried out in this study, and the results were as follows:1 Twenty-four introgression lines were constructed, which overlapped the interval of qSTV-11b.These twenty-four introgression lines originated from different plants of BC2F2 population.There were twelve STS markers in the interval of qSTV-11b, and these markers overlapped the physical distance of 330.50Kb.2 The resistance to RSV of twenty-four introgression lines was investigated. Compared to the infection rate of susceptible control Balilla, that of eight introgression lines was very significant, and that of fifteen introgression lines'was not significant, and that of one introgression line's was significant. Compared to the resistant control Dular, the result of these introgression lines was the same.3 The qSTV-11b was located between A38 and A36,and the physical distance of the two markers is 25.39Kb.There are five genes in the interval of the two markers,and difference is found in one of the five genes in the resistant and susceptible varieties by sequencing and blasting.So the gene was preliminarily considered as the candidate gene of qSTV-11b.