Abstract: 【Objective】 The purpose of the experiment is to reveal the relationship between cyclobutyl pyrimidine dimers (CPDs) accumulation and UV-B sensitivity in mung bean cultivars. 【Method】 Two mung bean cultivars (Phaseolus raditus L. cv. Qindou-20 and Zhonglü-1) were grown in greenhouse with treatment or without treatment of UV-B radiation (0.4 W·m-2) for four days. The UV-B-induced CPDs in mung bean DNA were quantified by enzyme-linked immunosorbent assay (ELISA) with specific monoclonal antibody and the relationship between CPDs accumulation and the UV-B sensitivity of mung bean seedlings were discussed. 【Result】 The UV-B-induced inhibition of the biomass and net photosynthetic rate of the primary leaves of cultivar Zhonglü-1 were respectively lower than that of cultivar Qindou-20, so that the cultivar Zhonglü-1 was more tolerant to UV-B than the cultivar Qindou-20. Meanwhile, the cultivar Zhonglü-1 had lower CPD accumulation and susceptibility to CPD induction, higher photorepair capacity and same dark repair capacity as compared with the cultivar Qindou-20. 【Conclusion】 Different UV-B sensitivities between two mung bean cultivars may be mainly caused by the differences in CPD accumulation, which are caused by the different susceptibility to CPD induction and the different photorepair capacities. In addition, the different susceptibility to CPD induction between two mung bean cultivars is related to the different levels of UV-absorbing compounds.

Key words: Mung bean, Cyclobutyl pyrimidine dimer (CPD), UV-B sensitivity, DNA repair