| Spaceflight is a new method of crop mutation breeding. This kind of mutagenesis is mainly caused by the space ion irradiation. In order to compare the effects of ion beam implantation and spaceflight on soybean mutation and to assess the feasibility of the replacement of space flight with ion beam implantation, the seeds of soybean [Glycine max (L.) Merr.] cv. Suinong14, one of the major cultivar in the Northeast Spring Soybean Region, were treated with the proton and N+ beam of different energy and fluence levels and spaceflight. The effects and methods of different treatments were compared by summarizing the mutation phenotypes of the progenies. The anslysis methods of soybean mutants were also discussed by anslyzing the rosette mutant of soybean Yuexia 03-3 which was induced byγ-ray irradiation in the current study. The results were summarized as follows:1. To assess the effects and parameters of the irradiation treatments on soybean, dry seeds of soybean cv. Suinong14 were treated with three energy (3.0,5.0,7.0 MeV)and four fluence levels(1×108 H+/cm2,1×109 H+/cm2,1×1010 H+/cm2,1×1011 H+/cm2)of proton beams. The results showed that various mutations could be induced with high energy proton beams. Seed germination was not affected by irradiation,whereas some other traits of the progenies were influenced,i.e.,the height of M1 plants was significantly increased,and in M2, early-maturing,etiolating,and sterile plants were found. Total mutant frequency was 6.81% and it increased with the increment of the fluence level but not with the energy level. The highest mutant percentage of the M2 plants derived from the treatment of 3.0 MeV,1×1011 H+/cm2 was 8.26%. The mutation partiality varied according to the energy and fluency levels. Early-maturity mutants were preferentially achieved when irradiated with 1×1010 or 1×1011 H+/cm2 fluence or with 5.0 MeV proton beam. Etiolated and sterile mutants were frequently obtained when treated with 109 H+/cm2 or 1010 H+/cm2 irradiation. When the seeds were irradiated with the energy of 3.0 MeV or 7.0 MeV,more sterile mutants and etiolated mutants were obtained than in other treatments.2. Space flight and ion beam implantation are both important methods for mutation breeding of crops. To assess the feasibility of the replacement of space flight with ion beam implantation, the effects of the two mutation methods were compared. The dry seeds of suinong 14 were treated with space flight and ion beam implantation. Space flight was carried out on SJ-8 Recoverable Satellite. And ion beam implantation was performed with N+ of 30keV energy including four levels of fluence of 4×1016, 8×1016, 12×1016 and 16×1016N+/cm2. The seeds treated with the two mutation methods were sowed under the same environmental conditions to analyze the biological effects on M1 generation and the mutation frequency of M2 generation. The results indicated that there was no significant differenc at seed germination rate, plant height, per pant pods number and per plant seeds number between the spaceflight and ion beam implantation treatments at 4×1016 and 8×1016N+/cm2 levels. No significant difference was found in M2 generation between spaceflight and ion beam implantation with the total mutation rate of 4.41% and 5.02% respectively. Mutants of early maturation, sterileness, multi-leaflet, dwarfness,deformed stem and round-shaped leaves were found in both treatments,which accounted for 97.3% of the total mutant frequency induced by space flight and 89% of ion beam implantation. The mutation rate and mutant type of the two treatment were similar. The data indicated here that space flight can at least be partially replaced by ion beam implantation in mutation breeding of soybean .3. Mutants in the M2 generation such as multiple stem tips,etiolation,deletion of unifoliate,malformated unifoliate,long unifoliate,malformated stem,and dwarf can be induced when the dry seeds of soybean cv. Yuexia 03-3 were treated byγ-ray both with the two dosages of 250 Gy and 500 Gy. There was no significant difference between the two treatments in mutation rate. Besides the mutants mentioned above,a mutant named Yuexia 03-3d,which has rosette phenotype,was also found when treated with the dosages of 250 Gy.4,The main phenotypes of Yuexia 03-3d were the severely shortened internode (dwarfness), the delayed maturity time and some other agronomic changes. Since spraying GA3 to the mutant was beneficial for the recovering of the internode elongation, it was identified as a mutant in GA pathway. The result of the SSR analysis showed that the polymorphic rate between the mutant and its wild type was 12.4%. The mutant presented here will be helpful not only for studying the GA3 metabolism but also for cloning the related genes. |
