入侵植物黄顶菊不同器官和不同发育阶段DNA表观遗传多样性变化特征

DNA甲基化是植物DNA普遍存在的一种表观遗传修饰方式，不仅在植物快速适应新环境中发挥重要的作用，还参与植物生长发育和器官分化特异性过程。本研究通过构建优化的甲基化敏感扩增多态性（MSAP）体系来分析入侵植物黄顶菊不同器官和同一器官不同发育阶段的组织甲基化变异特征。结果表明：器官特异性MSAP体系利用筛选的13对引物共扩增536条条带，其中引物EhHM7对表观遗传多样性贡献率最大，多态性百分比为92.45%；发育阶段特异性MSAP体系利用筛选的14对引物共扩增407条条带，其中EcHM1对表观遗传多样性贡献率最大，多态性百分比为80.56%。甲基化类型变异结果显示，黄顶菊不同器官（根、茎和叶）间以及同一器官不同发育阶段（老叶和嫩叶）的组织间均表现出显著的甲基化水平差异性，半甲基化、全甲基化和整体甲基化三种甲基化变异类型中茎组织的甲基化发生率最高，分别达到30.28%、19.37%和49.66%，老叶组织的全甲基化和整体甲基化率显著高于嫩叶组织，分别达到33.29%和52.77%。主成分分析结果显示，黄顶菊叶片个体分布较根、茎的个体分布更为密集，且嫩叶较老叶密集，表明根个体间和茎个体间均存在较大的差异，这种个体差异大于黄顶菊叶片的个体间差异，且老叶的个体差异大于嫩叶，这种个体间差异在样品采集时不可忽视。所以，在利用表观遗传学方法进行黄顶菊入侵性的研究中，必须要制定科学的采样方案，把植物器官和生长发育阶段特异性作为一个重要因素考虑在内。

Epigenetic diversity variation characteristics of Flaveria bidentis genome DNA of different organs at different developmental stages

As one of the epigenetic modifications, DNA methylation has become ubiquitous in plant genome DNA. It not only plays an important role in rapid adaptation to new environments but also participates in the process of plant growth and organ differentiation. In this study, we constructed an optimized MSAP system to analyze the methylation variation characteristics of different organs at different developmental stages of the same organs of Flaveria bidentis. The results showed that the organ-specific MSAP system amplified 536 bands by using 13 pairs of primers, in which the primer EhHM7 made the greatest contribution to epigenetic diversity, and the percentage of polymorphism was 92.45%. The developmental stage-specific MSAP system amplified 407 bands by using 14 pairs of primers, in which EcHM1 had the greatest contribution to epigenetic diversity, and the percentage of polymorphism was 80.56%. The results of varying themethylation type showed that there were significant differences in methylation levels among the different organs (roots, stems, and leaves)at different developmental stages of the same organs (old leaves and young leaves), among the three methylation variants of hemi-methylation, full methylation, and overall methylation, the methylation rate of the stem tissue was the highest, reaching 30.28%, 19.37% and 49.66%, respectively.The full-methylated and overall methylated rate of the old leaf tissue were significantly higher than those of the young leaf tissue, reaching 33.29% and 52.77%, respectively.The principal component analysis showed that the individual distribution of leaves of Flaveria bidentis were more intensive than that of roots and stem organs, and the young leaves were denser than the old leaves, which indicated that there were larger differences between individual roots and stems. This individual difference was greater than that of the leaves of Flaveria bidentis, and the individual difference of old leaves were greater than that of young leaves, which could not be ignored during sample collection. Therefore, during the studies on the invasiveness of Flaveria bidentis by using epigenetic methods, it is necessary to formulate a scientific sampling plan and consider plant organ and growth stage specificity as important factors.