Studies on the Utility of Artificial Mutations in Plant Breeding : XII. Induction and Gene Analysis of Male-sterile Mutants in Rice

Abstract

Seeds of three kinds of rice varieties were treated with EI (O. 5%, v/v) and X-rays:. (25kR), then male-sterile mutants induced were screened in the M₂-M₄ generations. In the present study, the plants that showed complete sterility in self pollination without abnormality of female organ were defined as "male-sterile mutants". Anthers of those plants were indehiscent, containing few or no good pollen grains. The EI treatments yielded the male-sterile mutants all over the three varieties with the frequencies of 0.30-0.38%, totaling eight mutants, while the X-irradiation was ineffective in inducing the mutants. F₁ hybrids from the crosses between the mutants and their original varieties exhibited a normal seed fertility under self- and open pollinations. The segregation ratio in F₂ showed that the mutants, except one, were controlled each by a single recessive gene. Allelism test with those recessive genes revealed that at least six different loci were responsible for the different male sterilities. These results may indicate that EI treatment is highly effective in inducing male-sterile mutants and that a considerable number of loci are concerened with male sterilities in rice.