Unlocking Fertility Secrets: Precise Restorer Selection for High Yielding Three-Line Hybrids Through Rf3 and Rf4 Gene Synergy in Rice (Oryza sativa L.)

Abstract

In the ever-growing population and resource constraints, the enhanced productivity is attained by harnessing hybrid vigour. The success of three-line hybrid breeding relies to a large extent on the precise identification of restorers to ensure fertile hybrids. This study is aimed to explore the genetic dynamics of fertility restoration in rice hybrids, with a specific focus on the interaction between the Wild Abortive Cytoplasmic Male Sterility (WA-CMS) and two crucial genes associated with Restoration of fertility (Rf) namely Rf3 and Rf4. Molecular screening of 105 diverse genotypes using RMS-SF21-5 and RM228 markers revealed distinct allelic combinations influencing fertility restoration. Subsequently, a subset with varying genotypic constitution of Rf genes was crossed with TNAU CMS 2A and COMS 23A. The evaluation of test cross progenies unveiled that most of the restorers belonged to Rf3Rf3/Rf4Rf4 genotype implying the significance of both genes in determining restorers. The genotypes RNR 15048, CBSN 513, IR64 DRT, CO 54, WGL 32100 and MTU1210 were identified as effective restorers. The low glycemic index of RNR 15048 and drought tolerance of IR64 DRT provide unique opportunity to develop hybrids with improved nutrition and climate resilience. Also, Marker-assisted selection, particularly the combined use of Rf3 and Rf4 markers, demonstrated a substantial increase in efficiency, emphasizing the need for a dual-gene screening approach. The findings offer valuable insights for a precise and time-efficient selection of restorers to develop high-yielding rice hybrids, highlighting the essential role of both genes in identifying optimal restorers.