Inheritance and fine mapping of a restorer-of-fertility (Rf) gene for the cytoplasmic male sterility in soybean

The cytoplasmic male sterility (CMS) line FuCMS5A and its restorer line FuHui9 were crossed to produce a segregating F2 population for pollen fertility assay and the genetic mapping of restorer-of-fertility (Rf) gene. Results showed that the individual F2 plants were fertile or semi-fertile based on their pollen fertility characteristics. The average ratios of viable pollen were 96.90% and 50.00% for each class of individuals. The segregation of F2 plants showed a good fit to a 1:1 ratio, which reflects a typical heredity pattern of gametophytic CMS with fertility restorer being controlled by a single dominant gene. Using bulk segregation analysis (BSA) and genetic mapping, the Rf gene was mapped on molecular linkage group J (chromosome 16), between the simple sequence repeat (SSR) makers BARCSOYSSR-16-1064 and BARCSOYSSR-16-1082 with the distances of 0.59 and 0.83 cM, respectively. Four SSR markers (BARCSOYSSR-16-1070, Sctt011, BARCSOYSSR-16-1076 and BARCSOYSSR-16-1077) were cosegregating with this Rf gene in the mapping population. These makers will greatly facilitate the maker assisted selection procedures in CMS breeding programs and it lays a foundation for further map-base cloning of the Rf gene.

► We conclude that soybean ZD type cytoplasmic male sterility (CMS) belongs to gametophytic male sterility.
► The fertility restoration of ZD type CMS is controlled by a single dominant gene.
► The restorer-of-fertility (Rf) gene was fine mapped on soybean linkage group J (chromosome 16).