[Effects of Cu2+ stress on DNA polymorphism of genome in foxtail millet of different genotypes].

Cu2+ is an essential element for plant growth, and is one of the major elements in the environment. In order to investigate the physiological characteristics and geno-toxicity effects of foxtail millet (Setaria italica (L) Beauv) under different Cu2+ stress, four genotypes of foxtail millet (Zhaogu, Huangmi, An06, D2-8) from Shanxi, China were cultivated for 30 days in a pot filled with soil of with different mass concentrations of Cu2+ (0, 50, 100, 200, 400 mg.kg-l). Effects of Cu2+ stress on DNA damage of genome in foxtail millet were studied using random amplified polymorphic DNA (RAPD) , and the contents of soluble sugar, proline and MDA were tested. The result showed that the content of soluble sugar had a trend of initial increased followed by decline in all four foxtail millet seedlings in response to the rising Cu2+ concentration, and the maximum value was 50 mg.kg-1. At Cu2 concentrations of 200 mg. kg-1 or more, the soluble sugar content in the four kinds of millet showed an average reduction of 32.44% to 56.5% compared to that of the control group. The result showed that proline synthesis was enhanced at low concentrations (less than 50 mg.kg-1) , but inhibited at high concentrations (more than 100 mg.kg-1), and the contents of MDA in the four genotypes of foxtail millet were significantly increased compared with the control group (P <0. 05). The changes occurring in random amplified polymorphic DNA profiles of the four genotypes of foxtail millet following Cu' treatment included loss of normal bands, appearance of new bands and variation in band intensity compared to the plantlet without treatment, showing that Cu2+ significantly affected the stability of the genomic DNA in the cells of millet seedlings. Additionally, the effect of DNA polymorphism changes was dose-dependent with the Cu2+ concentration. The different genotypes of millet showed different response in the physiological and genetic damage under Cu2+ stress. The change of DNA polymorphism using RAPD technique could be used as the biomarkers to find genotoxic effects of Cu2+.