Abstract:

Evidence indicates high increases in rice yield due to semidwarf gene sd1 in rice. But the dwarf stature being used is controlled by a recessive semidwarf gene sd1, which can sometimes cause fragility of genetic resource and yield decrease. These problems associated with this gene have been necessitated identification and utilization of new and better dwarf genes. The marker line material Duonieai（DA） used in the study is a dwarf mutant , however genetic analysis showed that its dwarf trait was controlled by two recessive semidwarf genes, sd1 and a new semidwarf gene. F₂ segregating population between Duonieai and Nanjing 6（N6）was established and SSR marker linkage analysis was performed on them. The new semidwarf gene was located between microsatellite markers SSR98 and SSR35 on chromosome 11, the genetic distances between them were 0.06 cM and 0.13 cM, respectively. Two BAC clones covering the two microsatellite markers had been sequenced with their full sequences being 154 kilobase and 156 kilobase, respectively. Also, 30 kilobase was overlapped between the two BAC clones. According to the sequence information on chromosome11 ,physical map revealed that few BAC clones were near the new semidwarf 93 kilobase, the new semidwarf gene could be delimitated within this 93 kilobase. The near isogenic line Xinduonieai（XDA）with the new semidwarf gene from a backcross between Nanjing6 and Duonieai was found insensitive to gibberellin.

Key words: Indica, Semidwarf gene, Linkage analysis, Gene location, Gibberellin