Observation of Revertants in CMS Line Zhenshan 97A and PGMRs Line HN5s

To compare the differences between the CMS(Cytoplamic Male Sterile Line) Zhenshan 97A and PGMRs (Photoperiod Sensitive Genic Male-Sterile Rice )HN5s in the sensitivity to physical and chemical inducing factors and to study the changes in pollen fertility under inducing conditions, pollen abortive type in the revertants offspring by self polleniation and the rate of fertile mutation ,which was obtained by the combination treatments of 60Co-γ irradiation , sodium azide and mature embryo culture,were observed. The following results were obtained :1) Male-sterile plant was converted into fertile revertants;2)Abortion type of pollen was changed into pollen free or spherical abortion type or stained abortion type;3) Photoperiod sensitive male-sterile plant was changed into thermal sensitive male-sterile plants. Furthermore it was put forward that the shift of sterility in photoperiod sensitive male-sterile rice was resulted from the reversion of the male-sterile gene to fertile gene and the accumulation in the course of self-cross in revertants or crossed with other plants under natural conditions.