A novel environment-induced genic male sterile (EGMS) mutant in indica rice
SummaryMale-sterile mutants were isolated from M2 and M3 generations of indica rice variety 26 Zhaizao, dry seeds of which had been exposed to 60Co-γ rays at a dose of 290 Gy. The mutants were planted in early season and ratooned in late season for two successive years for identification of fertility conversion in different growing seasons. One of the mutant lines was further observed in a growth chamber and in the field. Results showed that daily average temperature might be the major factor conditioning the male fertility conversion at a moderate daylength. The critical temperature for the male fertility conversion of the mutant grown under 12.5 h and 14.0 h daylength is about 23°C, below which the plant becomes completely male sterile. Its male fertility conversion character differs from other EGMS lines so far developed. The performance of the hybrids between the mutant and some other indica varieties demonstrated its good combining ability and its potential value in hybrid rice production. The obtained mutant line still sheds KI-stainable pollen grains under male sterilizing conditions. Nevertheless, pollen grains shed from the male sterile plants were much more vulnerable than from normal plants. At sucrose concentration below 1.5 M, the pollen grains from the mutant grown under male sterilizing conditions almost completely broke down, while above 1.5 M they became plasmolysed and shrunken. This is indicative of poor development of the membrane and walls of the pollen grains from the male sterile mutant, causing the pollen grains to be unfunctional. NBT test also clarified the abortion of the pollen grains from the mutant, which were formed in the male sterilizing environment.
Studies on response to photoperiod and temperature of the photoperiod-sensitive genic male sterile rice (PGMSR). I. Observation of fertility in PGMSRs under natural conditions at Hangzhou (30° 05′ N).
The change of fertility in PGMSRs, including 6 indica and 5 japonica rices, was observed under natural conditions at Hangzhou (30°05′N, 119°56′E, 6.5m). It was shown that the response of PGMSR to photoperiod and temperature was different with their genetic background and that the fertility transfer date varied in the tested PGMSRs.Temperature played an important role in fertility transfer of PGMSRs, as to indica, its role seems much more important or dominant.
Remove from Marked Records Artificially Induced Male-Sterile Mutants and Their Usages in Rice Breeding
Male-sterile lines were induced by gamma irradiation and ethyleneimine treatment of seed of Nihonmasari [Superior]. The segregation ratios in the M3 of nine of the 45 families obtained suggested monogenic inheritance of male sterility. Two of these nine lines were crossed with the fertile cultivar Pai-kan-tao. The segregation ratios in the F2 also indicated that male sterility in each line was controlled by a recessive allele at a single locus