Inheritance and mapping of male sterility restoration gene in upland japonica restorer lines

Several upland Japonica breeding lines, WAB450-11-1-3-P40-HB (Abbreviated as WAB450-11), WAB450-11-1-2-P61-HB (WAB450-13), WAB450-l-B-P-91-HB (WAB450-14), IRAT216, IRAT359, and IRAT104, possessing restoring ability for the Dian 1 type cms (cms-D) line Dianyu 1A were recently identified at Food Crops Research Institute, Yunnan Academy of Agricultural Sciences, P. R. China. In this study, the inheritance of restoring ability in these lines was characterized through the production of backcross populations to the male-sterile and maintainer Dianyu 1 lines. Each of the restorer lines was used to pollinate Dianyu 1A to form a F1 hybrid which was then backcrossed (1) with Dianyu 1B producing a BC1F1 population and (2) to the female parent Dianyu 1A producing a BC5F2 population. The lines were also crossed with the japonica restorer line C57, carrying the restorer gene Rf1 that was introgressed from indica, to form F1 hybrids, these hybrids were then testcrossed with Dianyu 1A to study the allelic relationship of their restorer genes to Rf1. The inheritance in these testcross populations indicated that the complete restoring ability of WAB450-11, WAB450-13, WAB450-14, IRAT216, IRAT359, and the partial restoring ability of IRAT104 were controlled by dominant genes, and the gene in WAB450-13, WAB450-14, and IRAT216 was allelic or identical to Rf1. When 136 SSR markers were used to score 143 BC1F1 individuals from Dianyu 1A/WAB450-13//Dianyu 1B, the japonica Rf1 allele was found to be located between RM171 and RM6100 on the long arm of chromosome 10, an interval corresponding to that known for the indica Rf1 allele. The distance between RM171 and Rf1 is 2.8 cM, and that between Rf1 and RM6100 is 4.9 cM. Similar linkage results were obtained from mapping 89 individuals of the corresponding BC5F2 population (Dianyu 1A/6/Dianyu 1A/WAB450-13).