Trait-specific improvement of a Cytoplasmic male-sterile line using molecular marker-assisted selection in rice
To specifically improve preharvest sprouting (PHS) and amylose content (AC) in the cytoplasmic male-sterile (CMS) line G46A, two simple sequence repeat (SSR) markers, RM3754 and RM447, that are closely linked to qPSR8, a major quantitative trait locus for PHS, were adopted to select for reduced PHS; SSR marker 484/485, which is tightly linked to the waxy gene, was used to select for AC. In the backcross progenies with G46B, the maintainer of G46A, as recurrent parent and ‘Lemont’ as donor parent, most plants with a homozygous Lemont allele at both RM3754 and RM447 showed good PHS resistance. Amylose content in the progeny of G46B/Lemont was significantly related to a difference in alleles at the 484/485 locus. Based on agronomic trait performance and evaluation for PHS and AC, 28 elite lines obtained from the BC3F5 generation were then used in further backcross schemes to breed improved CMS lines. Subsequently, two improved CMS lines showed traits similar to G46A but with improved PHS resistance and intermediate AC.