Molecular mapping of QTLs for overwintering ability of axillary buds in rice

The quantitative trait loci (QTLs) for overwintering ability of axillary buds (OAAB) were identified by using a F₂ population including 312 plants derived from a cross between an indica variety Shuhui527 and a japonica Glutinous variety 89-1. A molecular linkage map with 122 polymorphic SSR markers was constructed by the interval mapping. The OAAB of F₂ population was evaluated in winter, and overwintering seedling rate under low temperature was used as cold tolerance index for OAAB. A continuous distribution partial to sensitive cold parent for OAAB was observed in the F₂ population, OAAB was a quantitative trait controlled by polygenes. Three major QTLs concerned with OAAB located on chromosome 2, 3 and 7. The loci were on the region of RM256~RM250, RM218~RM232, RM320~RM560, respectively. Their contribution to phenotypic variation was 13.1%, 6.6% and 18.0%, respectively. Accumulated contribution was 30.9%.