Identification of Good Restorer Lines through Molecular Confirmation of Rf3 and Rf4 Genes in Rice Hybrids

Abstract

Pollen fertility can be restored by nuclear-encoded genes known as fertility restorer (Rf) genes. The initial stage in creating high-yielding heterotic hybrids involves the identification of restorers capable of effectively restoring the fertility of CMS lines. Hybrid rice breeding programs have proven effective in achieving these goals by utilizing cytoplasmic male sterility (CMS) systems in combination with restorer genes. Among these, Rf3 and Rf4 genes play critical roles in restoring male fertility and are essential components of successful hybrid rice breeding. In this study, we aimed to investigate the molecular conformation of Rf3 and Rf4 genes in a set of restorer lines and hybrids in rice. DNA was isolated from 10 restorer lines and 30 rice hybrids, two checks and KMR3R were used for comparison for positive alleles. Two functional markers, RM SF21-5 for Rf3 and RMS-PRR-9-1 for Rf4, were employed to identify the allelic status of the fertility restorer genes. Results revealed that among the 42 rice entries screened, five rice hybrids lacked both Rf3 and Rf4 genes and Four rice restorer lines and four hybrids were found to possess both Rf3 and Rf4 genes, making them valuable for hybrid breeding programs. Conversely, five hybrids lacked restorer genes and were unsuitable for such breeding programs. These findings establish Rf3and Rf4 as major fertility restoring genes in rice, consistently contributing to complete fertility restoration. The genotyping results provide valuable insights for selecting appropriate parental lines and restorers in hybrid rice breeding programs. The presence or absence of these fertility-restoring genes plays a crucial role in developing high-yielding and productive rice varieties through effective breeding strategies.