Genetic analysis of male sterility obtained from a rice cultivar Lebed backcrossed with Taichung 65

摘要

Background Male sterility is a useful agronomic trait for breeding of self-pollinating crops and is often observed in the progenies of hybrids of distantly related species, for example, Oryza sativa L. subsp. indica and O. sativa L. subsp. japonica . To explore new male sterile lines in rice, we performed successive backcrosses using a japonica cultivar Taichung 65 (T65) as a recurrent pollen parent and various indica cultivars as the initial female parents. Findings We observed male sterile plants in the backcross progeny from an indica cultivar, Lebed. Both fertile and sterile plants were present in the BCsub4/subFsub1/sub generation. The sterile plants segregated for fertile and sterile plants when backcrossed with T65 in BCsub5/subFsub1/sub, BCsub6/subFsub1/sub and BCsub7/subFsub1/sub with a ratio of 1:1. Conversely, all the backcross progenies from the fertile BCsub4/subFsub1/sub were consistently fertile. Anthers of the male sterile line were stunted and did not shed pollen; cross-sectional observations revealed defects in sporophytic cells. The male sterility appears to be caused by heterozygous alleles derived from T65 and Lebed. A male sterility gene was mapped between two INDEL markers on the long arm of chromosome 10, which corresponded to a 407?kb region in the Nipponbare genome. Conclusions Since the heterozygous Lebed allele acts as dominant sporophytic pollen killer, it would be useful for recurrent selection breeding of japonica rice.