Improvement Of Resistance To Rice Bacterial Blight Of Hybrid Rice Jinshan B By Means Of Marker Assisted Selection

The bacterial blight is one of the most serious rice diseases in the world, and it often caused rice grains greatly lost. The gene Xa21 which was with broad-spectrum resistance to bacterial blight was more and more paid attention to. In order to improve the resistance to bacterial blight of high quality rice male sterile line (maintainer line ) Jinshan A (B) , in this study, the Jinshan B and IRBB21 that carried gene Xa21 were used as parents to make backcrosses (Jinshan B for recurrent parent), and both foreground selection and background selection were carried out by means of marker assisted selection in the backcrosses. The main results were as follows:1) 44 and 40 plants with gene Xa21 were selected from BC] and BCa respectively through foreground selection by the use of a co-segregated STS marker MXA21 with gene Xa21.2) 500 SSR primers were used to filtrate the polymorphism between Jinshan B and IRBB21, and total 66 polymorphic SSR markers were selected, which basically covered the whole 12 rice chromosomes.3) When the genetic backgrounds of plants from both BCt and BC2 (the selected plants carried gene Xa21 and were morphologically similar to Jinshan B) were analyzed by using the polymorphic SSR markers, it could be found that their average genetic background recovery rates of BC1 and BC2 plants were 76.10% and 87.80% respectively, being close to the average genetic background recovery rates of conventional backcross (75.0% and 87.5% in BC1 and BC1, ,respectively).4) When compared the graphic genotype of plant B16 in BC1 with those of plants B25 and B29 in BC2 (both B25 and B29 were derived from the same ' backcross using plant B16 as female), It was found that the similar outcomes of background selection of B25 and B29 could be gotten both by the use of heterozagous markers of plant B16 and all the 66 SSR markers to analyze the genetic background of plants B25 and B29. Therefore, we could analyzed generations background by heterozagous markers of their female parents without using homological markers in order to saving lots of analysis time and cost.