重金属镉胁迫下入侵植物黄顶菊表观遗传变异特征

Epigenetic Variation Characteristics of Invasive Plant Flaveria bidentis Under Heavy Metal Cadmium Stress

为探究入侵植物黄顶菊在重金属镉(Cd)胁迫下耐受性获得的表观遗传机制,本研究通过网室盆栽试验模拟不同浓度Cd污染生境,采用甲基化敏感扩增多态性(MSAP)技术对不同Cd浓度胁迫[0(CK)、2(Cd-1)、4(Cd-2)和8(Cd-3) mg·kg^-1]处理植物叶片基因组DNA甲基化变异特征进行分析。结果表明,15对引物共扩增出726条甲基化条带,且引物多态性百分比为84.75%;随着Cd胁迫浓度的升高,黄顶菊叶片全甲基化和整体甲基化发生比例呈逐渐增加的趋势,Cd-1、Cd-2和Cd-3的全甲基化发生比例分别为CK的1.51、1.95和2.11倍,整体甲基化发生比例分别较CK升高了39.28、53.30和63.97个百分点;不同处理下叶片甲基化状态变化分析结果表明,Cd胁迫下黄顶菊基因组DNA重新甲基化和去甲基化2种甲基化模式均有发生,但以重新甲基化类型为主要变化模式;Cd胁迫下植物表型可塑性与表观遗传相关性分析结果表明,DNA全甲基化和整体甲基化水平与黄顶菊生长指标及地上部耐受性指数的表型可塑性呈显著负相关,与抗氧化酶活性、各组织Cd含量及富集与转移系数呈显著正相关。本研究结果从表观遗传学方向为入侵植物黄顶菊的防控提供了新思路。

In order to explore the epigenetic mechanism of tolerance acquisition of the invasive plant Flaveria bidentis under heavy metal cadmium(Cd) stress, a pot experiment was conducted to simulate different concentrations of Cd contaminated habitats. Methylation sensitive amplification polymorphism(MSAP) technique was used to analyze the genomic DNA methylation variation characteristics of plant leaves under different Cd stress[0(CK)、2(Cd-1)、4(Cd-2)and 8(Cd-3) mg·kg^-1]. The results showed that 726 methylation bands were amplified by 15 pairs of primers, and the percentage of primer polymorphism was 84.75%. With the increase of Cd stress concentration, the proportion of fully methylation and total methylation in leaves of Flaveria bidentis showed a gradual increase trend. The Cd-1, Cd-2 and Cd-3 was 1.51, 1.59 and 2.11 times the fully methylation level of the CK, respectively. Total methylation level of Cd-1, Cd-2 and Cd-3 increased by 39.28, 53.30 and 63.97 percentage point compared with the CK, respectively. The results of methylation analysis of Flaveria bidentis with different treatments showed that both remethylation and demethylation occured under Cd stress, but remethylation was the main transformative mode. Correlation analysis results showed that the levels of DNA fully methylation and total methylation levels were negatively correlated with phenotypic plasticity of growth and above-ground tolerance indexes, while positively correlated with antioxidant enzyme activity, Cd contents of different tissues, accumulation and transfer coefficient. The results of this study provide a new perspective for the prevention and control of invasive plant Flaveria bidentis from the aspect of epigenetics.