Evaluation of Restorability of Two Fertility Restorer Genes in the Rice Chromosome Single Segment Substitution Lines (SSSLs)

Abstract

Rice chromosome single segment substitution line (SSSL) S15, a strong restorer line for WA-, and DA-CMS, was recently isolated at Guangdong Provincial Key Laboratory of Plant Molecular Breeding, South China Agricultural University. The present study was carried out with the objective to investigate the genetic mode of fertility restorer (Rf) genes and the genetic relationship between WA- and DA-CMS systems. The SSSL S15 was used to pollinate WA-CMS line of Bobai A and DA-CMS line of Xieqingzao A for generation of two BC3F2 populations by using marker-assisted selection (MAS) and traditional backcrossing. The results were as follows: (1) The genetic effect showed a trend of WA-CMS DA-CMS in the genetic background of SSSL S15, and the effect of Rf4 was slightly larger than that of Rf3 for the two CMS systems. (2) Two pairs of dominant genes governed restoration of pollen fertility restoration, and some modifying or minor genes were involved in the inheritance of restorer ability besides Rf3 or Rf4 in SSSL S15, indicating that the genetic mode of Rf genes showed a qualitative-quantitative characteristic for WA-, and DA-CMS system. (3) When 202 SSR markers were used to analyze the genetic background and average length of substituted chromosome segments of the two BC3F2 individuals, carrying the genotypes Rf3Rf3/rf4rf4 or rf3rf3/Rf4Rf4, the mean of segments of inherited background of them was 1.0, while the average lengths of the substituted chromosome segments, corresponding to Rf3 and Rf4 loci, of them were 12.9 cM and 18.4 cM, respectively.