基于Hi-C技术从染色质高级结构层面解析短柄草的春化记忆机制

Vernalization is a plant-specific memory of cold environments, which is one of the important factors affecting flowering and even geographical distribution of crops. Therefore, the study of vernalization mechanism has important agricultural and economic value. Researchers have known and understood this classic memory phenomenon for nearly a century. Previously, researchers have made a gradual analysis of the regulation mechanism of vernalization. A lot of studies have shown that vernalization is regulated in the epigenetic and transcriptional levels in plants especially, vernalization memory in some individual genes, synergistic regulation in some big regions of chromatin, and collaborative memory among multiple genes in different chromatin regions. However, due to the limitation of technology, little is known about theses molecular mechanism of some vernalization memory features. Based on the high-resolution chromosome conformation capture (Hi-C) technology, this project plans to obtain the whole genome-wide chromatin spatial interaction in differently vernalized Brachypodium in order to find the chromatin spatial interaction structures related to vernalization memory, and especially to explore the vernalization memory mechanism of higher-order chromatin structure itself. Then from the new regulation level of higher-order chromatin structure, this project attempts to explain the memory features found in the epigenetic and transcriptional levels, so as to break through the bottleneck in the previous study and further provide theoretical support for elucidating the memory mechanism of eukaryotic cells.

春化是植物特有的对于寒冷环境的持续记忆，是影响农作物开花乃至地理分布的重要因素之一，因此对于春化机制的研究具有重要的农业和经济意义。研究者们关于这一经典记忆现象的认识和理解已有近百年。以往大量的研究结果表明春化在植物的表观修饰、转录水平等层面均存在调控。尤其是：一些基因本身存在春化记忆，一些染色质大片段存在区域性的协同调控，不同染色质区域的多个基因之间存在协同记忆。然而由于技术的限制，这些春化记忆特征的分子机理尚未解析。借助高通量染色质空间结构捕获（Hi-C）技术，本项目计划在不同春化阶段的短柄草中通过获得全基因组范围的染色质空间互作关系，以寻找春化记忆特异相关的染色质空间互作结构，特别是探究染色质高级结构本身介导的春化记忆机理。进而从染色质高级结构这一新的调控层面试图解析表观修饰、转录水平发掘的春化记忆特征，突破以往的研究瓶颈，为阐明真核生物细胞的记忆机制提供理论支持。

春化是植物接受长期低温从而加速开花结果的过程，具有重要的农业和经济意义。本项目我们借助新兴的高通量染色质空间结构捕获技术，在二穗短柄草中清晰的识别出了染色质高级结构层面的春化记忆，并成功绘制了春化过程中染色质高级结构的动态图谱。进而我们发现 Loop 结构对稳定单基因的春化记忆具有重要贡献，TAD 结构有助于表观修饰的区域化调控，染色质高级结构为表观修饰、转录水平多基因协同记忆提供了空间上的基础。本项目加深了我们对于春化记忆机制的全面理解，为粮食作物及经济作物的品质改良提供了新的思路和优异的改良靶点。