Abstract：Radiation mutation breeding has the characteristics of high frequency of mutation, large variation range and short breeding period, which is one of the main methods of breeding. In order to speed up the work, the previous study used 60Co-γ rays to irradiate Sophora davidii germplasm with the best production performance and carry out radiation mutation breeding. In this study, the variation in twelve M2 mutant populations of S. davidii which were induced by 60Co-γ radiation was evaluated by morphological characters and inter-simple sequence repeat (ISSR) markers. The results showed that compared with the control without radiation, the mutants were characterized with the increase or decrease of plant height and crown diameter, the significant increase of stem diameter, leaf length, leaf width and leaf area, and the reduction of the branch site height. The coefficient of variation of 8 phenotypic traits were between 19.72% and 55.46%. The degree of variation of each index was branching site height (55.46%)＞ plant height (53.24%)＞ crown diameter (47.91%)＞ leaf area (38.30%)＞ number of branches (36.84%)＞ stem diameter (36.10%)＞ leaf width (23.60%)＞ leaf length (19.72%). A total of 141 amplified loci were detected by 20 ISSR primers, of which 75 were polymorphic, and the polymorphic rate (PPR) was up to 53.2%. The Nei's genetic diversity (He) and Shannon's information index (I) were 0.248 3 and 0.377 9, respectively. The genetic similarity index based on ISSR data between the mutants ranged from 0.627 7 to 0.839 4, with a mean of 0.733 6. All mutants were clustered into 4 groups based on the morphological characters or the ISSR molecular markers, but the clustering results between two levels were not fully consistent. This study provides a scientific foundation and germplasms for further radiation breeding of S. davidii.
