A new gene located on chromosome 2 causing hybrid sterility in a remote cross of rice

Abstract

Abstract ‘Ketan Nangka’, the donor of the wide compatibility gene (WCG) showed typical hybrid sterility when crossed to a landrace, ‘Bai Mi Fen’, of Yunnan province in China. A genome‐wide analysis was performed for a backcrossed population of ‘Ketan Nangka’/‘Bai Mi Fen’//‘Ketan Nangka’ using a total of 143 simple sequence repeat markers and an expressed sequence tagged marker to cover the entire rice linkage map. As a result, two independent loci were found to cause hybrid sterility via female gamete abortion. The locus on chromosome 4 may correspond to S9 , but the other, on chromosome 2, was different from all the previously reported hybrid sterility loci and was designated as S29(t) following the hybrid sterility nomenclature. On the basis of allelic interaction which causes female gamete abortion, two alleles were found: S29 kn (t) in ‘Ketan Nangka’ and S29 bi (t) in ‘Bai Mi Fen’. In the heterozygote, S29 kn (t)/S29 bi (t) , which was semi‐sterile, female gametes carrying S29 bi (t) were aborted. An Aus variety from the Indian subcontinent, ‘Dular’, was found to have a neutral allele, S29 n (t) . Two molecular markers, RM185 and RM425, linked to S9 and S29(t) , respectively, will be useful for marker‐aided transfer of WCGs in hybrid rice breeding.