Identification of a new hybrid sterility gene in rice (bi Oryza sativa L.)

Abstract

Partial female gamete abortion which is revealed as hybrid sterility of panicles in most of indica/japonica crosses of rice (Oryza sativa L.) is due to an allelic interaction between indica-type allele S5-i and japonica-type allele S5-j at S5 locus on chromosome 6, while some varieties, such as Dular, have a neutral allele S5-n, and both the S5-n/S5-i and S5-n/S5-j genotypes are fertile. We report here that a new hybrid sterility locus was found in a hybrid of former Soviet Union japonica rice USSR5 and Chinese indica rice Guangjie 9. A back-crossed population (USSR5/Guangjie 9//USSR5) was made to analyze the spikelet fertility in the B1F1 population of 120 plants with 119 simple sequence repeat (SSR) markers on all the 12 chromosomes. As the result, two loci conferring the hybrid fertility were found, which acted independently of each other. Interestingly, the locus on chromosome 4 coincided with the previously identified S9, while the locus on chromosome 5 was distinct from all the previously reported ones. The new locus was thus designated as S31(t). Based on allelic interaction causing female gamete abortion, two alleles were found at S31(t), i.e. S31(t)-un in USSR5 and S31(t)-gi in Guangjie 9. An Aus variety, Dular, was assumed to have a neutral allele, S31(t)-n. The SSR markers of RM5586 and RM13 were considered to be useful for marker-aided transfer of the wide compatibility genes in the hybrid rice breeding.