重金属铅镉对濒危植物中华水韭(Isoetes sinensis)DNA甲基化的影响

Effect of Pb and Cd on DNA methylation of Isoetes sinensis, a rare plant

为研究古老植物对重金属胁迫的分子水平的响应,探究重金属对濒危植物DNA甲基化影响的特点,选择两种重金属Pb和Cd对濒危植物中华水韭进行胁迫处理,每种重金属设置3个处理浓度,胁迫处理至第28 d选取叶片,采用MSAP(甲基化敏感扩增多态性)技术测定DNA甲基化程度。试验结果表明:重金属铅和镉均能够对中华水韭DNA甲基化产生影响,甲基化总体水平基本一致(对照、Pb处理和Cd处理分别为46.96%、48.23%和48.1%),但全甲基化水平(Pb处理是28.34%,Cd处理是20.25%)均低于对照(33.91%),而半甲基化水平(Pb处理是19.89%,Cd处理是27.85%)均高于对照(13.04%)。甲基化增强的变化,以无甲基化或内外侧胞嘧啶半甲基化向内外侧胞嘧啶全甲基化变化的模式为主。去甲基化的变化,以内外侧胞嘧啶全甲基化向无甲基化或内侧胞嘧啶半甲基化或全甲基化变化的模式为主。铅和镉胁迫在导致中华水韭DNA甲基化增强所占比率方面几乎相等(39.04%和39.71%),而在去甲基化所占比率方面镉(46.86%)高于铅(33.92%)。

To investigate the molecular response of ancient plants to heavy metal stress and to explore the feature of DNA methylation in en-dangered plants exposure to heavy metals, Isoetes sinensis, an endangered plant, was stressed with three different concentrations of two heavy metals Pb and Cd, respectively. Then the degree of DNA methylation in the leaves were measured on the 28 th day using Methylation Sensitive Amplified Polymorphism（MSAP）technique. The results showed that the DNA methylated profile of I. sinensis was affected by heavy metal stress. There was no significant difference in the amount of DNA methylation between the test and control groups（CK, Pb and Cd was46.96%, 48.23% and 48.1%, respectively）, however, full-methylation level（Pb 28.34%, Cd 20.25%）were lower than control（33.91%）, in contrast, hemi-methylation level（Pb 19.89%, Cd 27.85%）were higher than control（13.04%）. The change of patterns from no methylation or hemi-methylation of inner and outer cytosines into full-methylation of inner and outer cytosines accounted for a large proportion in enhanced methylation aspects and that from full-methylation of inner and outer cytosines into no methylation or hemi-or full-methylation of inner cy-tosines occupied most of demethylation. The proportion of DNA methylation increased by both Pb and Cd stresses is nearly equal（39.04%and 39.71%）, but the proportion of DNA demethylation by Cd is higher than that by Pb（46.86% than 33.92%）.