镉胁迫下萝卜基因组DNA甲基化敏感扩增多态性分析

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 CdCl_2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CdCl_2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CdCl_2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。

Analysis of Genomic DNA Methylation Level in Radish under Cadmium Stress by Methylation-sensitive Amplified Polymorphism Technique

The level of cytosine methylation induced by cadmium in radish (Raphanus sativus L.) genome was analysed using the technique of methylation-sensitive amplified polymorphism (MSAP). The MSAP ratios in radish seedling exposed to cadmium chloride at the concentration of 50, 250 and 500 mg/L were 37%, 43% and 51%, respectively, and the control was 34%; the full methylation levels (C(m)CGG in double strands) were at 23%, 25% and 27%, respectively, while the control was 22%. 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 CdCl(2) concentration. Four types of MSAP patterns: de novo methylation, de-methylation, atypical pattern and no changes of methylation pattern were identified among CdCl(2) treatments and the control. DNA methylation alteration in plants treated with CdCl(2) was mainly through de novo methylation.