Young panicles from three rice varieties, Zhenshan 97A (WA type cytoplasmic male-sterile (CMS) line, indica), Hongyuan A (HL type CMS line, indica) and Baoyuan A (BT type CMS line, indica), were cultured on different media. Regenerated plants were obtained. Pollen fertility was examined. Characteristic of fertility-restoring mutants was examined. The main results were as follows: Two fertile revertants were found in R1 regenerated plants of Zhenshan 97A with 100% fertile pollens and more than 90% self seed set rate. One of the stabilized fertile revertants (coded A3-9-15-2) was named R type restoration which could restore the fertility of CMS lines, and its self seed set rate was over 80% in F1 hybrids. Genetic analysis of the progenies of the tested crosses indicated that the fertility restoration of Zhenshan 97A involved two pairs of restoring genes. The other fertile revertant was named B type restoration which could maintain the sterility of CMS lines for five generations all along. These two fertile revertants were similar to Zhenshan 97B in major agronomic characters. Three fertile revertants were found in R1 regenerated plants of Hongyuan A (coded HF-1, HF-2 and HF-3) and Baoyuan A (coded BF-1, BF-2 and BF-3) respectively. One excellent restorer line was obtained from the fertile revertants of Baoyuan A (coded BR-1) and Hongyuan A (coded HR-1) by means of genealogical method respectively. Development of fertility-restoring mutant by somaclonal variation could be used as an effective method to obtain restorer line of CMS line.

Key words: cytoplasmic male sterility (CMS), fertile revertant, in vitro culture, indica, japonica, Oryza sativa L.