缺乏适应于高寒牧区种植的豆科牧草是影响青藏高原草牧业健康发展的重要因素。花苜蓿（Medicago ruthenica）在青藏高原东缘广泛分布，是高寒地区唯一能越冬生长并完成生活史的豆科苜蓿属植物。前期研究发现，该植物在8-9月会形成许多地下越冬芽，这些芽能在-45℃安全越冬，具有极强的抗寒性，但其抗寒机理尚不明晰。本项目选取花苜蓿为试材，在青藏高原原生境下开展以下研究：1）跟踪观测地下芽在自然越冬过程中形态发育与生理特性变化，探明花苜蓿在高寒草地漫长冬季的生长节律；2）以此为基础确定取样关键时期，采用RNA-seq高通量测序技术对越冬芽进行转录组测序，通过差异基因表达分析，筛选出抗寒相关基因；3）利用拟南芥进行关键基因转化和功能验证。本研究旨在阐明越冬芽生长节律与抗寒性之间的关系，揭示花苜蓿适应高寒环境的分子机制，挖掘优异的功能基因资源，为苜蓿高原抗寒育种和栽培技术研究提供基础依据。

Lacking of adaptable cultivated legumes is the key problem affecting healthy development of grassland & animal husbandry in the Qinghai-Tibet Plateau(QTP). Medicago ruthenica, widely distributed in the eastern margin of the QTP, is the only species in Medicago genus that can adapt to alpine area. Previous studies found that this plant can form many underground overwintering buds (OWBs) in 8-9 momths.Those buds can survive at -45℃ in extremely cold winter. But the mechanism of OWBs cold resistance is still unclear. Therefore, the project selected wild M. ruthenica growing in the original habitat of QTP to research the following contents: 1) to reveal the growth rhythm of M. ruthenica in winter by tracking observation developmental and physiological changes of OWBs, 2) RNA-seq is used in this research to identify differentially expressed genes of OWBs responsive to cold hardiness at different developmental stages.3) Finally, the separated genes associated to cold hardiness are transferred to Arabidopsis to identify their function.The research will make the relationship between growth rhythm and cold hardiness of OWBs clear, clarify the molecular mechanism of cold hardiness of M. ruthenica , and isolate the functional genes, which can provide the base for breeding of new cold hardiness alfalfa varieties adaptable to cultivate in the QTP.