【摘要】 应用甲基化敏感扩增多态性（MSAP）技术分析了重金属镉（cd）胁迫处理后萝卜基因组DNA甲基化程度的变化。结果表明,经50、250和500mg/L CdCl₂处理后,MSAP比率分别为37%、43%和51%,均高于对照（34%）;全甲基化率（双链C^mCGG）分别为23%、25%和27%,而其对照为22%,表明重金属CdCl₂胁迫后,某些位点发生了重新甲基化。萝卜叶片DNA中总甲基化水平的增加与CdCl₂处理浓度呈显著正相关。甲基化变异可分为重新甲基化、去甲基化、不定类型以及与对照相同的甲基化模式等类型,Cd胁迫处理引起的植株基因组DNA甲基化程度的提高主要是重新甲基化。更多还原

【Abstract】 The level of cytosine methylation in- duced by cadmium in radish（Raphanus sativus L.） genome was analysed using the technique of me- thylation-sensitive amplified polymorphism （MSAP）（Table 1）.The MSAP ratios in radish seed- ling exposed to cadmium chloride at the concen- tration of 50,250 and 500 mg/L were 37%,43% and 51%,respectively,and the control was 34%; the full methylation levels（C^mCGG in double strands）were at 23%,25% and 27%,respectively, while the control was 22%（Fig.1,Table 2）.The level of increase in MSAP and full methylation indicated that de novo methylation occurred in some 5′-CCGG sites under Cd stress.There was significant positive correlation between increase of total DNA methylation level and CdC1₂ concentration.Four types of MSAP pattems:de novo methylation,de-methylation,atypical pattem and no changes of methylation pattern were iden- tified among CdC1₂treatments and the control（Fig. 2,Table 3）.DNA methylation alteration in plants treated with CdC1₂was mainly through de novo methylation（Fig.3）.更多还原