Genetic analysis of fertility restoration genes for WA-type cytoplasmic male sterility in Iranian restorer rice line DN-33-18.

Cytoplasmic genetic male sterility system can be used to exploit heterosis in grain crops only when the effective restorer lines are available. Crosses between an Iranian CMS line Neda A with three newly developed lines DN-33-1, DN-33-18 and DN-32-6 showed that only the cross of Neda-A/DN-33-18 had more than 80% pollen and grain fertility in F1 generation. The inheritance of fertility restoration in F 2 population of this cross was evaluated at flowering and grain filling stages. Pollen staining test with 1% I 2 KI solution showed segregation ratio of 15:1 (fertile: sterile), representing two nuclear independent dominant genes controlling the trait carried by fertile parent DN-33-18. Segregation for spikelet fertility in F 2 confirmed the results of pollen fertility test. Molecular tagging of fertility restorer genes with SSR markers showed that four markers RM258, RM171, RM591 and RM3148 produced polymorphic bands between two parents. Linkage analysis on F 2 recessive class showed that RM258 and RM171 (on chromosome 10) flanked to restorer gene Rf4 at the distances of 3.1 and 6.3 cm, respectively. In this study polymorphism was not detected for Rf3 gene using SSR markers RM1, RM443, RM315 and RM294 on chromosome 1 of rice but we found new SSR marker RM3148 linked with Rf locus at a genetic distance of 19.7 cm. Key words : Rice, cytoplasmic male sterility (CMS), inheritance, molecular tagging, simple sequence repeat (SSR) markers.