镉胁迫下萝卜基因组DNA甲基化敏感扩增多态性分析

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

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。

The level of cytosine methylation induced 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 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 （CmCGG 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 5^1-CCGG sites under Cd stress. There was significant positive correlation between increase of total DNA methylation level and CdC12 concentration. Four types of MSAP patterns： de novo methylation, de-methylation, atypical pattern and no changes of methylation pattern were identified among CdC12 treatments and the control （Fig. 2, Table 3）. DNA methylation alteration in plants treated with CdC12 was mainly through de novo methylation （Fig.3）.