Studies On Photoperiod-Thermo Sensitive Genic Male Sterile Line Huiyousos In Rapeseed (Brassica Napus L.)

The discovery and development of new photoperiod/thermo-sensitive male sterilematerials play important roles in two-line heterosis utilization. The material used in thisstudy was a new photoperiod/thermo-sensitive male sterile line Huiyou50S, which wasdeveloped from a spontaneous semi-sterile plant found in Brassica napus cultivarHuiyou50. The male sterility of Huiyou50S was controlled by recessive nuclear genes. Thefertility of F₁generation plants, BC1population and F2population were observed via thefield experiment to identify the genetic of male sterile gene; the critical sterility temperatureand temperature-sensitive period of the male sterile line were studied via growth chamberexperiment; The cytological characters of pollen and the anther development of Huiyou50Sat the different stages were compared with its isogenous fertile plants by techniquesincluding semi-thin sections, scan electronic microscopy, and pollen grains staining withaceto-carmine; BSA method was used to screen the molecule markers linked to the malesterile gene. The main results are as following:1. The research of fertility alteration was carried out in photo-thermo-controlledgrowth chamber under different temperatures and photoperiod. The results indicated thatfertility of Huiyou50S was controlled by both temperature and photoperiod, and showedmale fertility under short-day photoperiod and high temperature conditions. Under lowtemperature（day14℃/night12℃）, Huiyou50S kept the stable sterility under other the longand short-day photoperiod. When temperature rose, Huiyou50S became fertile gradually.Meanwhile, it was also controlled by photoperiod. Fertility was inhibited by the longerphotoperiod.2. The F₁generation plants and reciprocal cross F₁generation plants of Huiyou50Sand other3Brassica napus cultivars were all fertile. The BC1population segregated at a1:1ratio for fertility/sterility, and the F2population segregated at a3:1ratio for fertility/sterility, following the segregation proportion of1pair of recessive genes. It suggested that fertilityof Huiyou50S was controlled by one pair of recessive genes.3. The anther development of Huiyou50S was similar to that of Huiyou50F fromsporogenous cell, pollen mother cell, meiosis, to tetrad stage. At the uni-nucleate stage,although the exine formed, the protoplast of microspores condensed, and the cell becameempty. At last all cellular content of pollen degraded completely and only the empty anddistorted shell remained. The tapetal cells of Huiyou50S developed a large vacuole at thetetrad stage which was different from that of fertile plants. And its tapetal cells rapidlydisintegrated at the uni-nucleate stage, which occurred earlier than that in Huiyou50F, whilethe tapetum of Huiyou50F did not degenerate at this stage. In conclusion, the microsporesof Huiyou50S abort mainly at the uni-nucleate stage, and there are some associationsbetween pollen abortion and tapetal cells’ disintegration.4.286pairs of SRAP primers were used to screen the molecule markers linked to themale sterile gene, in which2pairs of primers （e8m8and e17m8） could amplify specificfragments between the male-sterile line and male-fertile line.