| Rosa roxburghii Tratt.(Rosaceae) is a peculiar fruit to China. As the fruits of this species are valued for their nutritional and medicinal characteristics, especially their high ascorbic acid(AsA) levels, it has been given widely attention at home and abroad. Now it has become an important fruit industry in Guizhou province, and the cultivation area has been expanded year by year. But because of the existing cultivar varieties is too single, far from satisfy the diversification demand of processing industry and market, it would limit the development of R. roxburghii industry in a certain extent. Therefore, this study use 60Co-? rays and chemical mutagens to mutagenize R. roxburghii to select appropriate mutagenic dose, and identify the mutagenic materials by morphology, cytology and molecular biology to obtain some genetic variation metatial which will establish metarial foundation for breeding new varieties of R. roxburghii. The main results are as follows:1. The annual cutting seedlings and dormant branches of R. roxburghii was irradiation with 60Co-? rays. The results showed that: R. roxburghii was sensitive to 60Co-rays, and can only bear in range of 0 ~ 30 Gy. When the irradiation dose was 10 Gy, the death rate of annual cutting seedling was 5 %, and 7.94 % of branches was mutagenesis, the branches length and diameter was increased?the internodal length were shortened; The cutting survival rate of dormant branches was 25.25 %, and 8 % of branches was mutagenesis, the leaf length and width were highly significant higher than control. Compared to the control, the phenological period of R. roxburghii after radiation were significant delayed.2. In this study, R. roxburghii seedlings were irradiation with different doses 60Co-? rays. The results showed that the survival rate of seedlings decreased with the increase of radiation dose. There was a highly significant decrease in survival rate of seedlings when the radiation dose was over 10 Gy, the LD50 was between 15 ~ 20 Gy. The plant shoot and root of seedlings growth were severely suppressed. The photosynthetic pigment and starch content gradually decreased with the increase of radiation dose, and there were significant differences among different treatments. The MDA content was significant increased with the increase of irradiation doses, and the soluble sugar content, soluble proteins content and free proline content increase first, and then decreased. The peak value of dissolubility sugar, soluble protein and free proline contents appeared at the doses of 10 Gy and 15 Gy, respectively. Comprehensive the effect of 60Co-? rays on LD50 and growth ?physiological characteristics of R. roxburghii seedlings, the optimum irradiation dose of was 15 ~ 20 Gy.3. In vitro propagation system of R. roxburghii(‘Guinong 5') was optimized. The result showed that: the best medium for axillary induction was MS+0.5 mg.L-1 6-BA+0.2 mg.L-1 IAA, and the induction rate was 91.1 %. The best multiplication medium was MS + 0.25 mg.L-1 6-BA + 0.05 mg.L-1 IAA + 1.0 mg.L-1 GA3, and the multiplication coefficient reached 2.58. The best rooting medium was 1/2 MS + 0.2 mg.L-1 NAA + 1.0 mg.L-1 IBA, the rooting rate was 96.67 % and the average number of roots was 5.67.4. The mutagenic effects of different concentrations of colchicine and different treatment durations on R. roxburghii germinating seeds and Stem-segment were observed. The results showed that the optimum concentration of colchicine and treatment duration was 0.1% with 24 h or 48 h for dipping seeds, and 0.2% with 48 h for soaking stem-segment.5. Morphological and physiological characteristics of some R. roxburghii tiuuse culture seedlings were changed after colchicine treatment. The results showed that the plant height, the internodal length and compound leaves index were decreased, stem diameter, leaf area, length and width of guard cells and stomatal length were increased; Meanwhile, the stomatal density were decrease and the contents of photosynthetic pigment were increased.6. SSR markers technique has been used to detect the 10 variation materials of R. roxburghii after radiation and chemical mutagenesis. There were significantly differences between 9 variation materials and control materials in bands, which indicated that genetic variation of the variation materials had already taken place. In the polymorphic amplification results, the main mutation types of bands were“the bands deletion type” and “the mixed type”. |
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