QTL analyses for anther length and dehiscence at flowering as traits for the tolerance of extreme temperatures in rice (Oryza sativa L.)

Abstract

Quantitative trait loci (QTLs) for anther length (AL), length of the dehiscence that forms at the apex of the anther [apical dehiscence length (ADL)] and at the base of the anther [basal dehiscence length (BDL)], and the percentage of longitudinal dehiscence (LD) in rice (Oryza sativa L.) were analyzed using data from two consecutive years (2009 and 2010). Backcross inbred lines (BILs) derived from backcrossing of the rice cultivars (Nipponbare × Kasalath) × Nipponbare (95 lines) were used in both years for the detection of the QTLs. Each phenotype was significantly correlated between the 2 years, though its heritability was low. The anther dehiscence is strongly under control from both the environmental and genetic factors. Four major QTLs (α < 0.05) were detected for AL, three for ADL, four for BDL, and one for LD, using composite interval mapping. These QTLs explained 47–42, 32–25 and 36–28 % of the phenotypic variation in total for AL, ADL and BDL in BILs in 2009–2010, respectively, and for LD, 25 % in 2010. The phenotypic effects of the QTLs were examined using 54 chromosome segment substitution lines (CSSLs) derived from Nipponbare × Kasalath. Four of the detected QTLs had significant effects in CSSLs with Kasalath-type segments at marker positions linked with the QTLs, and the CSSLs can, therefore, be donors for breeding rice with high-temperature tolerance.