老芒麦是青藏高原地区利用最为广泛的当家草种之一，在退化草地改良、放牧、栽培草地建植和高寒草地畜牧业发展中具有十分重要的价值和地位。干旱胁迫成为影响老芒麦牧草和种子产量、栽培利用范围的主要限制性非生物因素，但老芒麦抗旱相关性状的分子遗传机制研究几乎空白。本项目拟采用来源广泛的老芒麦种质群体为研究材料，系统评价其在环境下对干旱胁迫响应性状的变异规律，利用SSR和AFLP分子标记研究供试材料的群体结构和遗传多样性，基于RNA-seq和近缘植物抗旱相关基因的分析来筛选候选基因并鉴定SNP，开展候选基因与干旱响应性状的关联作图分析，发掘出与抗旱性状显著关联的候选基因和分子标记，为老芒麦抗旱分子育种奠定重要的技术和理论基础。

Elymus sibiricus L. (Siberian wildrye) is one of the most important cultivated forage grasses in Qinghai-Tibet Plateau(QTP). It plays a crucial role in natural grassland restoration, artificial pastures establishment and development of livestock industry in alpine steppes. With the clear drying trends in QTP, the impact of drought stress on E. sibiricus production of herbage and seeds, and cultivation extent has become a major abiotic factor. However, the molecular and genetic mechanism of E. sibiricus traits related to drought resistance are still in blank. In this project, we will use diverse E. sibiricus accessions with multiple geographic origins to screen the whole-plant physiological responses to drought stress and study variation condition, distribution rule and correlation of main related characters. Then we will use SSR and AFLP technique to characterize genetic diversity and population structure of the tested collection of E. sibiricus to provide useful resources for conducting association mapping. Next, based on RNA-seq results and GenBank-derived EST/clones of relative cereals, we select some candidate genes involved in physiological and molecular mechanism pathway of drought tolerance and identify their diploid SNPs. Finally, linkage disequilibrium (LD)-based association mapping will be carried out to identify significantly associated SNPs with drought tolerance-related traits, and in silico sequence analysis will be implemented further to identify putative functional amino acid substitutions. This project will help discover genetic and molecular mechanism of drought tolerance in E.sibiricus, and provide valuable insight for molecular breeding of E.sibiricus for drought resistance.