Effects of cadmium (Cd) stress on DNA polymorphism and some physiological characteristics in leaves of Phaseolus vulgaris seedlings were studied in present hydroponic experiments by using random amplified polymorphic DNA (RAPD) technique. The results showed that in the case of 7 days stress time, with the Cd concentration increased from 0 to 80mg/L, the malondialdehyde (MDA) and Cd content increased; the total soluble protein content, proline content and GSH content raised at low concentration condition (20mg Cd/L) whereas decreased under moderate and high concentration conditions (40 and 80mg/L Cd, respectively). A total of eight oligonucleotide primers (10bp) were found to produce unique polymorphic band patterns, and subsequently used to produce 46 bands in the normal leaves genomic DNA of Phaseolus vulgaris seedlings. The RAPD map showed obvious differences between control and Cd-exposed treatments. Compared with the control, the RAPD map of Cd-stressed leaves present appearance of new bands, disappearance of normal bands, increase or decrease of band intensities. So the genomic DNA template stability was significantly affected by Cd pollution, and the DNA polymorphisms detected by RAPD technique could be used as an analytic approach for detecting the genotoxic effects of Cd stress on plants, and is also used as a valuable index for breeding vegetables varieties of Cd-resistance and evaluating Cd toxicity in Cd pollution area.%采用随机扩增多态性DNA (RAPD)等技术,检测不同浓度镉(Cd)胁迫对菜豆幼苗叶片DNA损伤及相关生理特性的影响.结果表明,随着Cd处理浓度(0,20,40,80mg/L)的增加,菜豆幼苗中的Cd含量及叶片中丙二醛(MDA)含量升高；叶片中可溶性蛋白、脯氨酸、还原型谷胱甘肽在低浓度(20mg/L)Cd处理下含量增加,中、高浓度(40,80mg/L)Cd处理下减少.选取8条寡核苷酸引物(10bp),利用RAPD随机扩增技术,对菜豆幼苗叶片细胞基因组DNA进行扩增,8条引物均产生特异性谱带.正常叶片基因组DNA的RAPD图谱得到46条谱带.与正常组相比,Cd处理下利用不同引物扩增得到的RAPD图谱发生改变,呈现不同程度的谱带强度增强或减弱、谱带缺失或新增,与对照的RAPD图谱存在明显差异.Cd胁迫下基因组模板稳定性下降,并随Cd处理浓度的增加,稳定性下降幅度增大.利用RAPD技术获得的DNA多态性变化,可指示镉毒害生物遗传效应,并为镉污染地区蔬菜品种的选育及镉毒性的评价提供依据.
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