拟南芥幼苗超低温保存后DNA甲基化的遗传变异

运用MSAP技术分析了拟南芥（Arabidopsis thaliana）幼苗超低温保存后DNA甲基化的遗传变异情况。结果表明，在扩增的662条带中，对照和2个处理及其第2代间完全一致的带型有598条：发生变化的带型有64条，其中能遗传给第2代的有48条，占变异条带的75％。与对照相比，经超低温保存的样品新产生的甲基化位点有14个，而去甲基化的位点有22个。经过处理但未冷冻的与冷冻处理组之间带型一致的有624条，差异条带有38条，占5.7％，而对照与未冷冻处理组的差异率是7．45％，对照与冷冻处理组之间的差异率是6。63％。可见，拟南芥在超低温保存中，无论是经液氮冷冻还是未经冷冻处理，对材料的甲基化状态均有影响，而这种甲基化变化大部分是可以遗传的。

Variation of DNA Methylation in Arabidopsis thaliana Seedlings After the Cryopreservation

We analyzed the variation patterns of DNA methylation in Arabidopsis tha/iana seedlings after cryopreservation using methylation-sensitive amplified polymorphism. Of 662 fragments, 598 were shared by all the samples and their descendants; and among 64 different fragments, a varied 48 （75%） were genetically related to their descendants. Compared to the control, 14 sites showed de novo methylation, and 22 sites were demethylated in the samples after cryopreservation. Among samples treated with cryoprotection and after cryopreservation were 624 shared fragments and 38 fragments of difference, with 7.45% and 6.63% difference in the two treatment samples, respectively, as compared with the control. In conclusion, the results showed that whether cryostorage in liquid nitrogen or other treatments had impact on the DNA methylation states of the material in this study, and most of the change could be genetic to their descendants.