Fine Mapping Of Gene Resistant To Bacterial Leaf Streak In Rice (Oryza Sativa L.)

Bacterial leaf steak (BLS) has become a familiar epidemic rice disease, and caused serious yield loss in south China. It is dedirable to exploit the rice germplasm against bacterial leaf steak to improve the level of disease resistance of rice hybrids. Based on the research of formers, this study focused on the fine mapping of a resistance QTL of BLS, qBlsr5a. The main results are as follows:1 Donor parent Acc8558 (high resistant to BLS) and recipient parent H359 (high infectious to BLS) were used as material to develop two near-isogenic lines H359-BLSR5a and H359-BLSR3d, both of them contained one resistance QTL (qBlsr5a or qBlsr3d). Results of strain bacterium experiment showed that resistance to BLS of the two near-isogenic lines were significantly different from H359, and proved that the disease resistance QTLs (qBlsr5a and qBlsr3d) truely exists.2 Using H359-BLSR5a and H359-BLSR3d as parents crossed with H359 respectively to develope two F₂ populations comprising 2265 and 1913 plants. Resistance analysis of the F₂ populations indicated that the qBlsr3d and qBlsr5a could respectively explain 20.68% and 43.73% of resistance phenotypic variance.3 12 SSR markers between RM153 and RM413 (18.4 cM genetic map ) was choosed to analyze its' polumorphism between H359-BLSR5a and H359. 6 polumorphic makers, RM17734, RM5816, RM122, RM159, RM7029 and RM6317, were obtained.4 120 plants with high resistance to BLS from the F₂ population of H359-BLSR5a x H359 were selected to constructe a molecular map of 8 SSR markers by using Mapmaker/Exp 3.0 program. From the map, the QTL qBlsr5a was located between RM153 and RM17734, 0.4cM away from RM153 marker and 0.7cM away from RM17734 marker.