Developing rice lines possessing neutral alleles at sterility loci to improve the width of compatibility

To improve the width of compatibility for overcoming various sterilities in inter-subspecific hybrid rice, some elite lines combining several sterility-neutral genes were developed and the effects on mitigating various hybrid sterilities were tested. From Akihikari// IR36/Dular, neutral genes at gall and six sterility loci, S5, S7, S8, S9, S15 and S16, were combined and elite lines were obtained in their successive progeny. Four of the lines tested were confirmed to combine the neutral alleles S5-n, S7-n, S8-n, S9-n, S15-n and S16-n at the sterility loci and, among them, two harboured an additional gamete abortion-neutral allele, gall-n. F 1 s, which used the lines and various testers as parents, mitigated the spikelet sterilities by six sterility loci and gamete abortion by a gametophyte gene, gall. These lines could be selectively used as parents or donors to increase the width of compatibility of rice varieties for improving fertility in inter-subspecific hybrid rice breeding.