Development of a platform for breeding by design of CMS restorer lines based on an SSSL library in rice (Oryza sativa L.)

Exploitation of the heterosis of hybrid rice has shown great success in the improvement of rice yields. However, few genotypes exhibit strong restoration ability as effective restorers of cytoplasmic male sterility (CMS) in the development of hybrid rice. In this study, we developed a platform for the breeding by design of CMS restorer lines based on a library of chromosomal single segment substitution lines (SSSLs) in the Huajingxian74 (HJX74) genetic background. The target genes for breeding by design, Rf3(4) and Rf4(4), which are associated with a strong restoration ability, and gs3, gw8, Wx(g1) and Alk, which are associated with good grain quality, were selected from the HJX74 SSSL library. Through pyramiding of the target genes, a restorer line, H121R, was developed. The H121R line was then improved regarding blast resistance by pyramiding of the qBLAST11 gene. Hence, a new restorer line with blast resistance, H131R, was developed. The platform involving the Rf3(4) and Rf4(4) restorer genes would be used for the continuous improvement of restorer lines through breeding by design in rice.