Molecular screening for fertility restorer genes Rf3 & Rf4 of WA -CMS and evaluation of F1 hybrids in rice (O. sativa L.)

Abstract

In rice WA (Wild Abortive) CMS system is commercially used for hybrid seed production. In WA-CMS fertility restoration is governed by two independent and dominant genes namely Rf4 and Rf3. Conventionally, the process of screening for the trait of fertility restoration is by tedious testcross progeny evaluation. In this study, earlier reported SSR markers RM6100 and RM 10313 linked to Rf4 and Rf3, respectively have been utilized to screen one hundred breeding lines and identified that 61 lines to carry both Rf3 and Rf4 genes and these lines can be utilized in hybrid rice breeding as restorers. A set of eighteen restorer lines with different combination of Rf4 and Rf3 were selected for crossing with five CMS lines viz., APMS6A, Pusa 5A, IR58025, IR68897, IR79156 and IR68888 and seventy test cross progenies were evaluated for their fertility restoration based on pollen and spikelet fertility. The hybrids viz., APMS6A X GQ-86, IR 79156A X IR-55778R, APMS 6A X VG-269 and IR 68888A X BR-827- 35 were observed to have more than 90% spikelet fertility. In this study observed that restoration ability varied with different CMS lines hence CMS lines also playing major role achieving higher heterosis.