Young panicles from five rice varieties, Zhenshan 97A (WA type cytoplasmic male-sterile (CMS) line, indica), Hongyuan A (HL type CMS line, indica), Baoyuan A (BT type CMS line, indica), Nongken 58s (photoperiod-sensitive genic male-sterile rice (PGMR), japonica) and W6154s (thermo-sensitive genic male-sterile rice (TGMR), indica), were cultured on different media. 10 cases of male-sterile variants in three rice varieties, Hongyuan A, Baoyuan A and W6154s were found. Abortive pollen of rice could be classified into four types: pollen free type (PFT), typical abortion type (TAT), spherical abortion type (SpAT) and stained abortion type (StAT). The phenomenon that type of pollen abortion could change from one to another through tissue culture was found in rice somaclones in R1 generation. Male-sterile variants in R1 generation were crossed with ten typical maintainer lines and restorer lines (Zhenshan 97B, Erjiuai 4B, Hongyuan B, Baoyuan B, Taiyin 1, Minghui 63, Ce 64, IR24, IR26 and IR36) to investigate the restoring and maintaining relationship of these male-sterile variants. The main results were as follows: The restoring and maintaining relationship of one typical abortion type (TAT) variant in R1 regenerated plants which derived from Baoyuan A (coded 28-18) was the same as that of WA type. The variant had been backcrossed with their maintainer lines for five generations, and kept sterile all along. Four male-sterile variants, which derived from Hongyuan A (one was coded 24-1, StAT; the other was coded S14-1, TAT) and Baoyuan A (one was coded 28-5, SpAT; the other was coded 28-19, TAT), kept sterile continuously for five generations when they were backcrossed with the ten parents stated above. The other five male-sterile variants, which derived from Hongyuan A (coded 24-5), Baoyuan A (coded 28-35) and W6154s (coded WP-1, WP-2 and WS) turned into fertility with a lot of fertile pollens and more than 80% self seed set rate when they were crossed with the ten parents stated above.

Key words: in vitro culture, indica, japonica, male sterile mutants, Oryza sativa L., somaclone