镉诱导拟南芥幼苗DNA损伤

Cadmium-induced DNA damage of arabidopsis seedlings

采用随机扩增多态性DNA(random amplified polymorphic DNA,RAPD)标记技术,并结合幼苗的形态和生理指标,研究镉(Cd)胁迫对拟南芥(Arabidopsis thaliana)幼苗基因组DNA损伤的影响。结果表明,不同浓度(0.25～5.0mg·L-1)Cd处理24d后,拟南芥幼苗根生长受到显著抑制,地上部分可溶性蛋白质含量呈先升高后降低的趋势,但对拟南芥幼苗叶片数、鲜重及叶绿素含量影响不大。选用12条寡核苷酸引物对拟南芥幼苗地上部分与根系基因组DNA进行PCR(polymerase chain reaction)扩增,发现处理组与对照组RAPD图谱之间存在明显差异,且与镉浓度之间存在剂量-效应关系。基因组模板的稳定性(genomic template stability,GTS)随着Cd浓度的增加而降低。3个处理组幼苗地上部分GTS分别为91%、89%和80%;相应根部GTS分别为71%、67%和60%。研究表明,利用RAPD技术获得的拟南芥DNA多态性变化可作为检测镉遗传毒性效应的生物标记物。比照其他几个指标,拟南芥幼苗根部RAPD谱带变化的敏感性更为优异,具有较好的应用前景。

By using random amplified polymorphic DNA （RAPD） technique in combining with morphological and physiological observation, this paper studied the genomic DNA damage of Arabidopsis thaliana seedlings under the Ca stress. After treated with 0.25, 30 and 5.0 mg·L-1 of Cd for 24 days, the root elongation growth of the seedlings was inhibited, the total soluble protein content in shoots decreased after an initial increase, but the leaf number, fresh weight, and chlorophyll content were less affected. Using 12 oligonucleotide primers （10 bp） to amplify the genomic DNA of the seedlings shoot and root cells by polymerase chain reaction （PCR）, it was observed that the RAPD profiles showed obvious differences between the normal and Cdexposed plantlets, and the change effect was dosedependent. The genomic template stability （GTS） decreased with increasing Cd stress. The GTS of the shoots in the treatments 0.25, 3.0 and 5.0 mg·L-1 of Cd was 91%, 89%, and 80%, and that of the roots was 71%, 67%, and 60%, respectively. In sum, the changes in the DNA polymorphism of A. thaliana seedlings detected by RAPD technique could be used as a biomarker to detect the genotoxic effect of Cd on plants, and the changes in the RAPD profiles of A.thaliana roots were more sensitive than the other indicators, being more suitable for the diagnosis of soil pollutants.