Variation characteristics of female semi-sterile mutant rs(s) in rice induced by space flight

Objective  To reveal the variation characteristics of female semi-sterility in rice induced by space flight.

Method The morphologic, cytological, physiological and genetic characteristics of a female semi-sterile mutant rs(s) obtained in conventional indica rice ‘Qiu B’ through space flight mutagenesis were studied. The setting rates of the mutant and its wild type, as well as their reciprocal cross F₁ and F₂ populations, were investigated. Cytological observations of pollen and embryo sac fertility of the mutant and the wild type were conducted. The content changes of auxin (IAA), cytokinin (TZR), abscisic acid (ABA) and gibberellin (GA₃) in young ears of parents were determined.

Result The mutant rs(s) was female semi-sterile and it had normal stamen development, indicating the semi-sterility might be controlled by a single recessive gene. During the development, the ovary was shrift and thin, the elongation of the stigma was not obvious, and the pistil was abnormal in the mitotic stage of embryo sac development, which leaded to embryo sac abortion. The content of IAA increased sharply at the 6th stage of young panicle differentiation.

Conclusion The mutant rs(s) is a new female semi-sterile mutant. The auxin content is up-regulated in the mitotic stage, which may be the main cause of pistil development malformation and female semi-sterility.