荠菜适应性进化机制-表观基因组多样性

Adaptation is common in nature. Plants are sessile organisms, thus environmental changes are crucial to their reproductive success. Epigenetic variation potentially provides a mechanism for plants to rapidly adapt to different environments, therefore investigating patterns of epigenetic variation in natural populations is a prerequisite for understanding the role of natural epigenetic variation in adaptation to local environments. Capsella bursa-pastoris originated in the Middle East, and was introduced into China very recently. However the C. bursa-pastoris plants are widely distributed in multiple environmental conditions in China, and show great phenotypic differentiation, such as in flowering time. In previous studies we found that the molecular diversity of the Chinese plants was extremely low, in combination with the significant morphological changes, it is suggested that epigenetic variation may play an important role in the rapid adaptation of the species in China. In this study, we plan to analyse the epigenomic variation of 96 Chinese accessions, by sequencing their DNA methylome using whole genome bisulfite sequencing. In addition, we will compare the epigenomic diversity with phenotypic variation, genome and transcriptome differentiation for these accessions, in order to thoroughly understand the mechanisms of adaptive evolution in this species. The full representation of epigenomic diversity in C. bursa-pastoris will accelerate studies in other plants to provide insight into general principles of adaptive evolution.

适应在生物界中普遍存在。植物是固着生长的有机体，环境变化对其生长繁殖影响很大。表观遗传变异为植物快速适应多变的环境创造了机会。因此，探索植物的表观遗传变异模式有助于深入理解其适应环境的进化机制。荠菜起源于中东地区，传入中国的历史很短，然而其在中国的分布很广泛，可在多种生境生长，并且开花时间等表型性状发生了显著的适应性分化。过去我们发现中国荠菜的遗传多样性非常低，可见表观遗传变异对其适应性表型的形成尤为重要。本项目拟在前期研究的基础上，利用全基因组DNA甲基化测序技术对中国荠菜的表观基因组多样性进行初步窥探，并结合性状分化实验、基因组和转录组分化来全面探讨荠菜的适应性进化机制。本项目的实施将为植物适应性进化研究提供新的参考思路。

适应在生物界中普遍存在。植物是固着生长的有机体，环境变化对其生长繁殖影响很大。表观遗传变异为植物快速适应多变的环境创造了机会。因此，探索植物的表观遗传变异模式有助于深入理解其适应环境的进化机制。荠菜起源于中东地区，传入中国的历史很短，然而其在中国的分布很广泛，可在多种生境生长，并且开花时间等表型性状发生了显著的适应性分化。过去我们发现中国荠菜的遗传多样性非常低，可见表观遗传变异对其适应性表型的形成尤为重要。此外，很有必要从性状差异、基因组分化等方面探索荠菜的适应性进化机制。本项目首先利用全基因组DNA甲基化测序技术对欧亚大陆的荠菜的表观基因组多样性进行初步窥探，发现DNA甲基化水平的分化与核苷酸变异推断的遗传结构相似，并且DNA甲基化水平与温度因子相关。其次，性状分化研究揭示了表型可塑性是荠菜在全球成功扩散的主要驱动因素。此外，项目还对部分中国荠菜个体的重测序数据进行了分析，并完成了基因组和环境关联分析，揭示了荠菜在中国存在适应性的扩散。再者，项目完成了高质量荠菜分型基因组的组装，为进一步分析重测序数据奠定了基础。项目总共产生287个个体约2.9 Tbp的重测序数据。本项目结合表观遗传、表型性状和基因组探讨了荠菜的适应性进化机制，为植物适应性进化研究提供新的参考思路。