铜胁迫对不同基因型谷子幼苗基因组DNA多态性的影响

Effects of Cu^(2+) Stress on DNA Polymorphism of Genome in Foxtail Millet of Different Genotypes

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.

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 CuE＋ 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 chanze of DNA Dolvmorohism usin RAPD techniaue could be used as the biomarkers to find genotoxic effects of Cu2＋ .