A preliminary identification ofRf*-A619, a novel restorer gene for CMS-C in maize (Zea maysL.)

C-type cytoplasmic male sterility (CMS-C) is widely utilized for hybrid maize seed production. However, genetic mechanisms underlying the fertility restoration are very complicated. At present, there is a divergence on the number of fertility restorer genes in maize inbred line A619 for CMS-C. To further elucidate the restoring mechanism of A619, we used genetic analysis and molecular markers to confirm the restorer genes of maize inbred line A619 for C-type male sterile line C48-2 in this study. Firstly, the fertility segregations of (C48-2 × A619)F2populations were investigated under three environments during 2013–2015. The segregation ratio of fertile and sterile plants in the F2population fit to 15:1 via chi-square test and this result suggested that there are two dominant restorer genes in A619 for CMS-C, i.e.,Rf4and a novel gene namedRf*-A619. Next, based on the sequence differences betweenRf4and its recessive allelicrf4, a novel dominant marker F2/R2 was developed and validated to genotypingRf4in the F2population. Through genotypic analysis, we found that there were a certain amount of fertile individuals withoutRf4which accounted for 3/16 in the F2population via chi-square test at the 0.05 level. These results provided another proof to sustain that the inbred line A619 contains one additional restorer gene for CMS-C fertility restoration exceptRf4. At last, we used one SSR marker which is tightly linked with the dominant restorer geneRf5to analyze those fertile plants withoutRf4in the F2population. The PCR amplification results showed thatRf*-A619is not allelic toRf5but a novel restorer gene for CMS-C. These results not only provide a basis for the mapping and characterization of a novel restorer gene but also give a new insight into the mechanism of CMS-C fertility restoration.