鬼箭锦鸡儿与荒漠锦鸡儿简化基因组进化分析及其对气候变化的分子适应机制研究

It remains elusive whether the plants occurring in the Qinghai-Tibetan Plateau and western desert regoin shared the common responses to the climatic changes and environmental heterogeneity since Quaternary. Then microclimatic caused by landscape changes and human activities could also promoted intra and interspecific divergence. In the present project, we selected Caragana jubata. and C. roborovskyi to compare the genetic diversity and climate adaptation inter- and intraspecies，which based on GBS analysis. As closely related Eurychoric Caragana species-pairs, they respectively adapted in the Qinhai-Tibetan plateau alpine steppe and become constructive species in the desert region of Northwest China. It seemed that early origin but differentiated gradually influenced by the microenvironments due to the qinghai-tibet plateau uplift. We will apply genotyping by sequencing (GBS) to detect genetic diversity, gene flow, and selection of individuals between and within populations, firstly compare phylogenetic tree and analysis phylogeographic structures, which build on neutral and non-neutral SNP pairs; secondly, clarify all historical changes and evolutionary process that resulted in the current distributions of two species. It will be a good case of studying patterns of genomic divergence response to climatic changes, and may shed light on the underlying evolutionary processes: Since Quaternary till now, the alpine and desert Caragana species share the same pattern of genetic diversity, or not? Such detailed comparisons will effectively reveal the adaptation mechimanism of these two plants, and also for further conservation and unitilization of these Caragana species resources.

第四纪以来异质性生境和气候变化对青藏高原地区和西部荒漠地区分布植物物种的遗传多样性和物种演化是否具有相同的作用是值得深入研究的重要课题。本项目拟选择锦鸡儿属近缘种鬼箭锦鸡儿和荒漠锦鸡儿进行研究，比较其种内种间遗传多样性分布规律及应对环境和气候变化的适应机制。广布于青藏高原的鬼箭锦鸡儿和西北荒漠地区主要建群种之一荒漠锦鸡儿在该属中起源较早，且受青藏高原隆升影响深广。通过简化基因组测序对中性与适应性基因分别构建系统发育树，并进行群体遗传结构分析，阐明两个近缘物种异域分布在不同生境的种群，在基因流水平、选择作用强度等方面的遗传变异规律，全面了解种群现状并追溯现代分布种群的进化历程。结合环境因子比较高原和旱区分布植物在第四纪和近期的环境变化中的气候响应趋势和遗传多样性的变化式样，揭示近缘物种适应不同非生物环境的进化机制，同时也为锦鸡儿属物种的种质资源保护和利用提供理论支持。

第四纪以来异质性生境和气候变化对青藏高原地区和西部荒漠地区分布植物物种的遗传多样性和物种演化是否具有相同的作用是值得深入研究的重要课题。本项目通过对锦鸡儿属两个近缘物种的进化历史和适应机制进行比较研究，探讨青藏高原及高寒山地分布的鬼箭锦鸡儿与西北荒漠干旱地区分布的荒漠锦鸡儿在不同种群中由于所处地域的环境的差异及历史上和近期的气候变化造成的植物基因谱系的时空变化。基于简化基因组SNP的遗传多样性PCA分析和种群遗传结构Structure分析表明鬼箭锦鸡儿主要分为3个亚群，青藏高原外的高山种群为一个亚群，川藏及其边界的种群为一个亚群，青海甘肃及祁连山脉以东的种群为一个亚群。PCA显示川藏亚群和甘青亚群是朝向不同的环境梯度方向形成替代群体。荒漠锦鸡儿可分为2个亚群，青藏高原祁连山区（张掖，嘉峪关，山丹等地）及祁连山以西种群（天山东北段乌鲁木齐）为一个亚群，武威以东蒙新高原荒漠区的种群为一个亚群（临夏，榆中，贺兰山等地），两个群体有差异，但在考虑了所有种群后发现种群呈替代分布类型。SNP揭示的青藏高原祁连山区亚群和蒙新高原荒漠区亚群也朝向不同的环境梯度方向形成替代群体。将适应不同气候生境的两个锦鸡儿属近缘种种群进行基因组范围SNP变异信息和部分种群叶形态和功能性状进行关联分析，发现两物种遗传变异与环境梯度下种群的叶形态与功能性状分化相关。本研究揭示了两个近缘锦鸡儿属植物基因遗传多样性分布及种群遗传结构和青藏高原隆升引起的环境寒化和旱化演变有关，遗传变异时空格局与种群地理分布区域的相关性揭示了非生物环境的差异与遗传变异之间的关系，同时也为有效保护该属宝贵的野生种质资源提供理论依据。