Molecular Inheritance Of The Photoperiod And Thermo-sensitive Genic Male Sterile Gene For Nongken58S In Rice

The discovery of Nongken58S provided a possibility for hybrid rice breeding method from three-line system to two-line system. Since then, through tireless efforts of researchers, various photo-thermo sensitive genic male sterile rice have been successfully breeded from Nongken58S. The genetic separation mode of the photo-period and thermo sensitive genic male-sterile gene, genetic allelism, the molecular mapping and cloning of the photoperiod and thermo-sensitive genic male-sterile genes are all have made great progress. Particularly, the photoperiod sensitive genic male-sterile gene pms3has been successfully cloned by the team of Zhang Qifa of Huazhong Agricultural University, in2011. Their study suggests that photoperiod-sensitive male sterility of Nongken58S is regulated by a lncRNA of1,236bases in length, which was named LDMAR(long-day-specific male-fertility-associated RNA), located in the12th chromosome of rice. A spontaneous mutation causing a single nucleotide polymorphism (SNP) between the wild-type and mutant, the G→>C change of the SNP altered the secondary structure of LDMAR. This change brought about increased methylation in the putative promoter region of LDMAR, which reduced the transcription of LDMAR specifically under long-day conditions, resulting in premature programmed cell death (PCD) in developing anthers, thus causing photoperiod-sensitive male sterility (PSMS).In this paper, photoperiod-sensitive genic male sterile rice Nongken58S and its derivatives—TGMS Line7001S, Changxuan3S,1103S, Pei’ai64S, W6154S, Guangzhan63S and their hybrid progenies were taken as materials, and the fertility alternation, frequency distribution and the molecular genetic law of Nongken58S photoperiod sensitive genic male-sterile gene were studied under the artificial light and temperature conditions, the main results are as follows:1. Fertility of Nongken58S and7001S is determined by day-lenth, fertility of W6154S, Guangzhan63S, Changxuan3S,1103S and Pei’ai64S is determined by temperature. Nongken58S and its derivatives PTGMS hybrid F1(including NK58S/W6154S, NK58S/Guangzhan63S, NK58S/1103S, Changxuan3S/7001S, W6154S/Guangzhan63S and PA64S/Guangzhan63S) are infertile under the conditions of long-day and high temperature, indicating that their sterility gene are alleles. Under conditions of long-day and high temperature, pollen fertility of F2segregating population of Nongken58S/W6154S, Nongken58S/Guangzhan63S, and Changxuan3S/7001S there are all sterility. This showed that their sterility gene are alleles. Under conditions of short-day and high temperature, ratio of fertile plants and sterile plants in F2segregating population of Nongken58S/W6154S and Nongken 58S/Guangzhan63S are close to1:1, pollen fertility of Changxuan3S/7001S F2were all sterility. Under conditions of short-day and low-temperature, F2plants of Nongken58S/W6154S and Nongken58S/Guangzhan63S were all fertile.2. Genotype detection of PSGMS gene pms3showed:genotype of7001S, Changxuan3S,1103S and Pei’ai64S were the same as Nongken58S, which has the G→C change of the SNP. But the genotype of W6154S and Guangzhan63S were different from Nongken58S, their SNP site is G. Can be inferred, the G→C change of the SNP in the LDMAR is not the only factor regulating photo-thermo sensitive genic male sterility of rice. In hybrid F2of Nongken58S/W6154S, Nongken58S/Guangzhan63S and Changxuan3S/7001S, under conditions of short-day and high temperature, genotype of fertile plants were all C and genotype of sterile plants were all G. It indicates that, pollen fertility of genotype-C plants is determined by day-length, pollen fertility of genotype-G plants is determined by temperature.3. Nongken58S and its derivatives PTGMS hybrid F1(except W6154S/Guangzhan63S and Guangzhan63S/W6154S) under different conditions of day-length and temperature processing, which their pollen fertility positively related to the expression level of pms3in the young spike anther. Which indicated that, the pollen fertility of Nongken58S and its derivatives—TGMS Line7001S, Changxuan3S,1103S, Pei’ai 64S, W6154S, Guangzhan63S is indeed regulated by LDMAR. Because there is not enough transcription of LDMAR under long-day and high temperature condition, the pollen sterility. But the expression level of pms3in the young spike anther of the cross F1S of W6154S and Guangzhan63S did not show a positive correlation with their pollen fertility, indicating that the molecular regulation mechanism of fertility of photo-thermo sensitive genic male-sterile rice is complex, it’s not regulates by a single factor.