[Mapping of two fertility-restoring gene for WA cytoplasmic male sterility in minghui63 using SSR markers].

F2 population derived from Shanyou63, F1 hybrid developed from the cross Zhenshan97 A/Zhenshan97B, was used in this study. Fertile bulk was constructed by polling equal amount of 15 highly fertile lines. Sterile bulk was obtained by pooling equal amount of 15 highly sterile lines. Minghui63 and Zhenshan97A, parents of Shanyou63, were analyzed with 302 pairs of SSR primers. 244 pairs of primers gave amplification products, of which 58 pairs of primers on 12 different chromosomes showed polymorphism between the two parents with polymorphic frequency up to 23.77%. Gene bulks were further assayed with the 5 pairs of primers. RM1 on chromosome 1 and RM258, RM304 on chromosome 10 was found to be polymorphic between the two gene bulks. In theory, there should be no difference detected between the two gene bulks except for the target traits governed by fertility-restoring genes. RM1, RM258 and RM304 were probably related to the restorer genes. Ten highly fertile and ten highly sterile lines were selected from F2 population of Shanyou63 to screen the gene bulks. The results showed that specific bands of Minghui63 were detected in all ten highly fertile lines while not observed in all the sterile lines. It indicated that the three SSR markers might be linked to fertility-restoring genes. Dominant lines were not selected due to their inalbility to distinguish recombinant lines from non-recombinant lines. Pure recessive lines were chosen to conduct mapping analysis. A total of 53 highly sterile lines were selected from 900 lines of Shanyou63 F2 population to estimate the genetic distance between three SSR markers and fertility-restoring genes respectively. The results demonstrated that recombination occurred in 2, 3, lines with RM1 and RM258 while no one with RM304. Using MAPMAKER/EXP 3.0, the genetic distance between RM1, RM258, RM304 and the related restorer genes were calculated as 1.9, 2.9 and 0.0 cM, respectively. It is possible that the fertility restoring gene(s) on chromosome 10 for three different types of cytoplasmic male sterility(WA, BT and HL) are of the same, or belong to a gene family.