Microsatellite-Aided Screening for Fertility Restoration Genes (Rf) Facilitates Hybrid Improvement

DNA markers enabled to determine the chromosomal locations of the two Rf genes (Rf3 and Rf4) in the wild-abortive cytoplasmic male sterility (WA-CMS) system. Four simple sequence repeats (SSRs) RM171, RM258, RM315 and RM443 were used to detect the allelic status with respect to the fertility restoration genes (Rf3 and Rf4) in 300 rice cultivars or breeding lines. The results revealed that out of 300 lines, 90 lines screened had Rf3, 65 lines had Rf4, and 45 lines had Rf3 and Rf4 alleles. Furthermore, 45 lines selected using SSR markers were mated with a CMS line (IR58025A) to analyze their restoring ability. Offspring of all the test lines except HHZ8-SAL9DT1-Y1, HHZ5-SAL9-Y3-1 and IDSA77 exhibited higher pollen and spikelet fertility (> 80%), thus confirming they bear the Rf alleles. The hybrid offspring of ARH12-6-1-1-B-3-1, IR32307-10-3-2-1 and Sahel 329 had the highest pollen fertility (97.39%, 98.30% and 97.10%, respectively) and spikelet fertility (95.10%, 97.07% and 96.10%, respectively).