Restorer gene of wild abortive cytoplasmic male sterility (WA-CMS) system Khao Dawk Mali 105
(KDML 105) and Chai Nat 1 (CN 1) rice cultivar was studied. Pollen fertility, Spikelet fertility and molecular
markers linked to restorer genes at Rf3 and Rf4 loci were investigated in F1 hybrid of the cross between
IR58025A and KDML105, IR58025A and CN 1 and F2 population. The results showed that CN 1 was
classified as fertile or R line. Whereas KDML 105 was classified as fertile or B line. Pollen fertility assay of
F2 plants suggested that the restoration of male sterility in CN 1 being controlled by a single nuclearindependent
dominant gene. In addition, analysis of an influence between the restorer gene and pollen fertility
by ANOVA revealed that the restorer gene at Rf4 locus could restore male sterility in CN 1. Therefore, Thai
rice cultivars could be classified by RMS_PPR9_4 marker, which is the restorer gene at Rf4 locus.