| In the century of 1970s and 1980s, Chinese pear cultivar'Dangshansuli'in domestic and southeast Asia's market deeply favored by consumers. In rencent years, because lack of the research about new varieties, cultivation techniques and storage aspects of post-processing. Degradation appeared on the quality descend in produce. It is not only to solve the problem by tandard cultivation technology. Besides Chinese pear cultivar'Dangshansuli'variety itself exists quality defects, it also have many problem to solve, such as Single species, no early and medium strains etc. So choose the excellent new varieties is great for economic benefit and the income of peasantry will also remarkable. This experiment try to use radiation mutagenesis of restingshoot, To research the grow and effect of physical radiation in Chinese pear cultivar'Dangshansuli', and preliminary explore the radiation mutation breeding in Chinese pear cultivar'Dangshansuli'.1. The dormant branch of Chinese pear cultivar'Dangshansuli'was treated with 60Coγ-ray irradiation and than grafted. The survival rate of treated bud and the length of shoot growth were investigated. The results showed that the survival rate of bud treated with the dose of 30Gy, 40Gy and 50Gy was 0.7257, 0.5427, 0.194, and of which the length of shoot growth was 48.21, 35.47, 25.67, respectively. Ten suitable random primers were screened out from 42 ones. The treatment with 40Gy dose was the greatest in variation by RAPD-PCR amplification of the genomic DNA. Therefore, it was proposed that the survival rate of bud and the length of shoot growth were decreased as the irradiation dose increased.2. The results showed that the optimal concentration of the four important components-Taq DNA polymerase,Mg2+, dNTPs and primer were 1.25U, 2.5 mmol/L, 0.3 mmol/L and 10mmol/L respectively in total 25μl reaction volume of RAPD. Thereby RAPD system in pear genomic DNA analysis had been established. The schedule of RAPD-PCR program was 2min initial denaturation at 94℃, then 1 min denaturation at 94℃, 1 min anneal at 36℃, 1min extension at 72℃, 40 cycles amplification, and 10min final extension at 72℃.3. By many times experiment, the genomic DNAs of pear were amplified by RAPD analysis using the 10 steady arbitrary primers screened from 42 ones. That is, S51,S1461,S1465,S1467,S1469,S1474,S1490,S1508,S1513,S1518.4. The DNA fingerprint constructed by the special bands of 8 arbitrary primers had been established. 5. To test the Genomic DNA variation after radiation, we get total of 71 bands including 22 specific bands. Different doses of radiation lead different degree of variation. The most bands of ten primers is S1513 which has five bands. The least bands of ten primers are S51 and S1490 which are both one band. For 32 genomic DNA samples amplification, 15 samples have specific bands, the rate is 47%. The samples named 40-6 have 11 specific bands. The samples named 50-2 have 3 specific bands. The mutation rate of five samples in 30 Gy treatment is 24%, average rate is 20%, the mutation rate of five samples in 40 Gy treatment is 27%, average rate is 23%, the mutation rate of five samples in 50 Gy treatment is 24%, The average rate is 19%.
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