青藏高原乡土牧草垂穗披碱草响应环境变化的种群分化及适应机制

Elymus nutans Griseb., as an important local forage grass in alpine region, is a perennial, caespitose species with a great ecological and economic value in genus Elymus (Poaceae).The special ecological adaptability to the complicated cold alpine environment had been formed during the long period of evolution. However, the effect of the phenotypic plasticity and genetic differentiation on environmental changes was still unclear. Therefore, the different populations of E. nutans along the environmental gradients in Qinghai-Tibet plateau were collected for studying the function mechanisms. The common garden trials was applied to analyze the phenotypic variation, and reveal the key phenotypic traits and their plasticity. Based on the genotyping by sequencing (GBS) technology and the methylation sensitive amplified fragment length polymorphism markers (MSAP), the population genetic variation were detected, which revealed the genetic variation pattern and genetic structure, as well as the epigenetics. Finally, based on the genetic data, the association analysis was conducted to excavate the crucial loci of the ecological adaptability combine the phenotypic and environmental factors data, These results in the study would not only reveal the genetic and epigenetic mechanism for the ecological adaptability, but also provide an important reference and theoretical guide for conservation and utilization of germplasms, as well as the marker assisted breeding of E. nutans.

垂穗披碱草是禾本科披碱草属重要的多年生物种，是高寒牧草的代表种之一，具有重要的生态和经济价值。它在长期的进化过程中，形成了对高寒复杂环境独特的生态适应性，但关于其遗传机制研究还很少，特别是表型可塑性和遗传分化在其适应环境变化中的作用机制还不清楚。本项目拟采集青藏高原环境梯度上的野生垂穗披碱草种群，通过同质园种植试验分析其表型变异，揭示响应环境变化的关键表型性状及可塑性；借助基因测序分型技术GBS和甲基化敏感多态性标记MSAP检测供试种群的遗传变异，揭示其遗传变异和表观遗传的变异模式和遗传结构；在此基础上，联合表型和环境因子数据进行关联分析，挖掘其与环境因子、表型性状显著关联的遗传位点，解析其高寒生态适应性的遗传机制，并为垂穗披碱草种质资源的保护、利用及育种提供重要的理论依据。

为了揭示青藏高原乡土牧草垂穗披碱草对高寒复杂环境独特的生态适应性，本项目采集了来自青藏高原的31个野生垂穗披碱草种群对其形态学表型、遗传结构、分化模式及与气候因子的关联等方面进行了研究。研究结果表明，供试的垂穗披碱草居群表现出了丰富的表型变异和分化，其中小穗和小花等性状受环境影响较为明显。供试种群的遗传多样性水平总体呈现出“东高西低”的趋势，且其遗传结构和表观遗传结构总体呈现出相似的类型和分化模式。降水相关的环境因子与垂穗披碱草居群遗传多样性参数密切相关。环境距离(IBE)和地理距离(IBD)对垂穗披碱草种群的遗传分化均有显著影响，同时IBE模式相比于IBD模式在垂穗披碱草自然居群的遗传分化上具有更强的驱动作用。本研究结果可以为垂穗披碱草种质资源的保护、利用及育种提供重要的理论依据。项目执行期间发表论文3篇，培养研究生2名。