Abstract: The genetic diversity of 74 mutagenic progenies M5 of 3 cotton varieties, Arcot-1, Su9108 and J11, irradiated by γ-ray were analyzed with 39 polymorphism SSR primer pairs. The results are as follows. Polymorphic loci of SSR markers which can detected among the mutagenic progeny M5 of 3 cotton varieties accounted for 51.3%, 48.7% and 66.7% to the total respectively, and the averages of diversity indexes (H') among the mutagenic progeny M5 of 3 cotton varieties were 0.997, 0.648, 1.187 respectively. The variance range of genetic similarity coefficient of SSR markers among the mutagenic progeny M5 of 3 cotton varieties and its original CK were 0.6515～0.9697，0.6970～1.000，0.5524～08095 respectively, and the averages were 0.8637, 0.9206, 0.6818. The pair similarity coefficient that was higher or equal to 8.000 was more than 60.0% for the mutagenic progenies M5 of two varieties (Arcot-1 and Su9108). The pair similarity coefficient that less than 7.000, was 62.5% for the mutagenic progenies M5 of J11. The analysis of molecular markers indicated that abundant genetic variation can result and genetic base in original varieties can be broadened from theγ-ray radiation. The study also clarified that the radiation of different cotton varieties resulted in the different variation, and provided detective method and theoretic base for germplasm enhancement by usingγ-ray radiation.

Key words: cotton, SSR marker, radiation, genetic diversity