Abstract: This study employed high-throughput transcriptome sequencing to analyze gene expression changes in Medicago truncatula under salt stress （150 mmol·L^-1 NaCl） and alkali stress （135 mmol·L^-1 NaHCO₃+15 mmol·L^-1 Na₂CO₃） at five time points： 0 h， 6 h， 12 h，24 h and 48 h. The results showed that alkali stress induced more drastic gene expression changes， with downregulated genes generally outnumbering upregulated ones. Differentially expressed genes were significantly enriched in pathways related to ABA signaling transduction， osmotic regulation， antioxidant defense， and ion homeostasis. A total of 60 genes were commonly upregulated and 16 genes were commonly downregulated under both salt and alkali stresses. The commonly upregulated genes were mainly involved in stress-resistance mechanisms such as hormone regulation and signal transduction， whereas the commonly downregulated genes covered multiple functional categories including hormone signaling and cell wall remodeling. This study elucidates key genes involved in the responses of M. truncatula to salt and alkali stresses and identifies candidate genes for salt and alkali tolerance， providing a theoretical basis for molecular breeding of alfalfa.

Key words: Medicago truncatula, Salt and alkali stress, Transcriptome analysis, Mechanisms of stress tolerance, Differentially expressed genes

摘要： 本研究采用高通量转录组测序技术，分析蒺藜苜蓿（Medicago truncatula）在盐胁迫（150 mmol·L^-1 NaCl）和碱胁迫（135 mmol·L^-1 NaHCO₃+15 mmol·L^-1 Na₂CO₃）下，0 h，6 h，12 h，24 h，48 h 五个时间点的基因表达变化。结果显示，碱胁迫诱导的基因变化更剧烈，下调基因普遍多于上调基因；差异表达基因显著富集于脱落酸信号转导、渗透调节、抗氧化防御及离子平衡等通路。盐与碱胁迫下共上调基因 60 个、共下调基因 16 个，上调基因涉及激素调控、信号转导等抗逆机制，下调基因涵盖激素信号、细胞壁重构等多个功能类别。本研究揭示了蒺藜苜蓿响应盐碱胁迫的关键基因，筛选出耐盐耐碱候选基因资源，为苜蓿分子育种提供理论基础。

关键词: 蒺藜苜蓿, 盐和碱胁迫, 转录组分析, 耐逆机制, 差异表达基因