Studies On Pyramiding Of Senescence-inhibition Gene And Genes For Resistance To Bacterial Blight And Blast In Rice (Oryza Sativa L.)

Senescence-inhibition IPT gene, resistance genes to bacterial blight Xa23 and to blast Pi-b were pyramided in rice by marker-assisted selection (MAS). According to molecular detection and identification of resistance, 16 FI plants carrying IPT genes and Xa23 were obtained from the multi-cross. Then the plants were used to be crossed with parental lines of two-line hybrid rice, 9311, E32, Pei'ai 64S and W9834S etc. Seventeen BC,F, plants carrying genes Xa23, Pi-b and IPT genes pyramided, and 6 BC2F] plants with Xa23 and IPT genes pyramided were detected. A numerous plants carrying Xa23, Pi-b or IPT genes were acquired. They may be useful in rice breeding.The completely dominant gene Xa23 with high efficiency of genetic-transfer for resistance to bacterial blight(BB) was proved in F1, BC1F1 and BC2F1 progenies of the multi-cross by identifying using the specific strain P6 of BB. The progenies with Xa23 for BB resistance could be screened at the seedling stage. The reliability that SSR marker "RM206" was utilized to select Xa23 was also confirmed.The results indicated that there may be other resistance gene to blast in He'xi 15 besides Pi-b , and the parents of two line hybrid rice, 9311, E32 and Pei'ai 64S may also possess resistance gene to blast.