铜胁迫对不同基因型谷子幼苗基因组DNA多态性的影响

采用室内盆栽土培法,以4种基因型谷子(D2-8、安06、黄米、朝谷)为供试材料,研究了不同浓度Cu2+胁迫对谷子幼苗体内可溶性糖、脯氨酸、丙二醛(MDA)含量和基因组DNA多态性的影响.结果表明,经50~400 mg·kg-1Cu2+处理30 d后,4种谷子幼苗体内可溶性糖含量与对照相比呈现先上升后下降的趋势,在50 mg·kg-1时达到最大值.当浓度为200mg·kg-1以上时,4种谷子的可溶性糖含量的平均降幅为对照的32.44%~56.5%.脯氨酸则表现为低含量(≤50 mg·kg-1)的促进和高含量(≥100 mg·kg-1)的抑制效应,MDA含量均有增加且与对照差异显著(P<0.05).Cu2+胁迫下不同基因型谷子幼苗基因组DNA的RAPD图谱发生明显变化,表现为单条或多条RAPD谱带的增加和缺失或者荧光强度的改变,细胞中基因组模板DNA的稳定性下降,DNA多态性变化与Cu2+浓度之间存在剂量-效应关系.不同基因型谷子对Cu2+胁迫的生理和遗传损伤响应存在差异.利用RAPD技术获得的DNA多态性变化可作为检测Cu2+遗传毒性效应的生物标记物.

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^-1). 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 Cu²⁺ 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⁺.