Molecular detection of WA-CMS restorers from tropical japonica-derived lines, their evaluation for fertility restoration and adaptation

Abstract

Hybrid rice based on wild-abortive cytoplasmic male sterility (WA-CMS) is important in boosting rice production, which requires diverse parents to harness heterosis. For this, exploiting the diversity of japonica through tropical japonica (TRJ) lines is an excellent route. In this study, 310 TRJ-based new plant type (NPT) lines were developed and evaluated for Rf3 and Rf4 genes. Gene-based (DRRM-Rf3-5 and DRRM-Rf3-10) and functional marker (RMS-SF21-5) targeted Rf3 locus, while gene-linked (RM6100) and functional marker (RMS-PPR9-1) targeted the Rf4 locus. The frequency of the restorer allele of Rf3 gene was lower when compared to that of Rf4. Combined phenotypic and molecular screening using gene-based and functional markers identified 42 lines that carried Rf3 and/or Rf4 genes. All the selected lines produced fertile F1s when crossed to a WA-CMS line, “Pusa 6A”, but with varying levels of spikelet fertility. This is the first report of a marker-cum-phenotype-based restorer selection using TRJ-derived lines. Multilocation evaluation of these lines at three locations indicated better adaptation for grain yield in some of the lines.