FAN, SHUGUO*, CHENGYE LIANG, AND HONGXIAN LIU. South China Institute of Botany, Academia Sinica, Guangzhou 510650, P. R. China. - Somaclonal male sterile and fertile variation of rice (Oryza sativa L.).
79 cases of male sterile variants in seven rice materials, Zhenshan
97B, Hongyuan A, Baoyuan A, W6154s, IR26, Minghui 63 and Nanguang-zhan
were found, in which 72 cases belonged to R1 generation (regenerated
plants from rice somaclones), and seven to R2 generation (plants from
first self-pollination, viz, progeny obtained by self-fertilizing the
regenerated plants). 10 673 regenerated plants were obtained in R1
generation, the frequency of male sterile variation was 1.02%
(0.85~1.08%). Male sterile variants were found in Zhenshan 97B and
Taiyin 1 in R2 generation, and the average male sterile variation
frequency in Zhenshan 97B and Taiyin 1 was 2.22% and 1.89%
respectively. 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. One
chimera was obtained from R1 regenerated plants of IR26 and Minghui 63
respectively. Fertility segregation was found from R2 generation of
Taiyin 1 and Zhenshan 97B respectively. Genotype was the main reason
in the course of inducing male sterile variants. Male sterile
variation was found in all rice materials except Nongken 58s, IR24,
Zhenshan 97A and Taiyin 1 in R1 generation. Dedifferentiation of
explants was essential to producing male sterile variation, and 2,4-D
played a decisive role in this course. The frequency of male sterile
variation in somaclones might be affected by the duration of
subculture passage. The frequency of male sterile variation in R2
generation (around 2%) was higher than that in R1 generation (around
1%). The higher frequency of male sterile variation in R2 generation
showed that the mutant frequency of one site of a pair of genes from
the wild type was much higher than that in a homozygous mutant (two
sites of a pair of genes undertaking mutants at the same time).
Key words: cytoplasmic male sterility (CMS), fertile reversion, in vitro culture, indica, japonica, Oryza sativa L.