Mutagenic Effects Of ⁶⁰Co-γ Rays On Different Drought Resistance Wheat

Recently, the rapid development of radiation mutation breeding has greatly enriched germplasm resources. Herein the effects of different radiant intensity of ⁶⁰Coγ-rays on the seed vigor, protecting enzymes, seeding growth, and mitosis in root tip cells of four drought-resistance wheat seeds, e.g., Xinong-889, Xinong-979, Pubing-143 and Xiaoyan-22, were firstly investigated. Then the physiological indexes, such as the content of chlorophyll, soluble protein and malondialdehyde (MDA), and the membrane permeability of four wheat seedlings, were also assayed. The main results are as follows:1. ⁶⁰Coγ-rays radiation stimulated the cell mitosis in root tip, however, it inhibited the cell mitosis in root tip under low dose radiation. The higher dosage of ⁶⁰Coγ-rays radiation was applied, the higher rates of chromosome and nucleus aberration occurred. The most sensitive one was Xinong-889. According to the linear regression analysis, in a 0-300 Gy dose, the linear relationship between the aberration rates of chromosome and nucleus of Xinong-979 and the radiant intensity of ⁶⁰Coγ-rays displayed the highest degree of fitting.2. In a 100-300 Gy dose, there was no influence of different ⁶⁰Coγ-rays on the germination rates of the above-mentioned four wheat seeds. ⁶⁰Coγ-rays radiation stimulated the root and seedling growth, and the priority sequence of sensitivity was Xiaoyan-22>Xinong-979>Pubing-143>Xinong-889. Under a dose of 300 Gy, ⁶⁰Coγ-rays radiation inhibited the seedling growth of Xinong-979 and Xiaoyan-22.3. Obviously, ⁶⁰Coγ-rays radiation stimulated the activities of protecting enzymes SOD, CAT, and APX. The reason was proposed. First, the mutated gene was produced by radiation, the protecting enzymes system was then activated to resist and repair radiation damage.4. ⁶⁰Coγ-rays radiation stimulated the content of chlorophyll, soluble protein and MDA of four wheat seedlings, but the different influence of radiation on four varieties was also found. Under a dose of 100 Gy, radiation clearly stimulated the membrane permeability of four wheat seedlings. However, to the same wheat species, the change of membrane permeability of wheat seedlings was not obvious with the increase of the radiation dose.