Abstract: Soil salinization is a key abiotic stress factor constraining the sustainable development of agriculture in China. Alfalfa （Medicago sativa L.） is an important high-quality leguminous forage with significant value for the improvement and efficient utilization of salinized lands. SPL （SQUAMOSA promoter binding protein-like） transcription factors play an important regulatory role in plant growth and development as well as in response to abiotic stress. In this study， the MsSPL3 gene was cloned from alfalfa and its function in response to salt stress was preliminarily investigated through bioinformatics analysis， expression pattern analysis， and yeast functional verification. The results showed that the open reading frame （ORF） of MsSPL3 was 420 bp in length， encoding 139 amino acids， and contained a typical SBP domain， belonging to the SPL transcription factor family. The MsSPL3 protein was localized in the nucleus. It exhibited the highest expression level in stems and the lowest in flowers， and was significantly induced by abiotic stresses such as salt-alkali stress， abscisic acid （ABA）， and simulated drought. Overexpression of MsSPL3 significantly enhanced the tolerance of yeast to salt stress. In summary， the findings suggest that MsSPL3 is involved in the response of alfalfa to salt stress， and provides a theoretical basis for subsequent molecular breeding for salt-alkali tolerance in alfalfa.

Key words: Alfalfa, MsSPL3, Salt tolerance, Functional validation

摘要： 土壤盐渍化是制约我国农业可持续发展的关键非生物胁迫因子。紫花苜蓿（Medicago sativa L.）是重要的优质豆科牧草，在盐渍化土地的改良与高效利用中具有重要价值。SPL（SQUAMOSA promoter binding protein-like）转录因子在植物生长发育及响应非生物胁迫中发挥着重要调控作用。本试验克隆了紫花苜蓿MsSPL3基因，结合生信分析、表达模式分析以及酵母功能验证，初步探究了MsSPL3在紫花苜蓿盐胁迫应答中的功能。结果表明，MsSPL3开放阅读框（Open reading frame，ORF）全长420 bp，编码139个氨基酸，具有典型的SBP结构域，属于SPL转录因子家族。其蛋白定位于细胞核，在茎中表达水平最高，花中表达水平最低，受盐碱、脱落酸（Abscisic acid，ABA）及模拟干旱等非生物胁迫显著诱导；过表达MsSPL3能够显著增强酵母对盐胁迫的耐受性。综上，研究结果推测MsSPL3参与了紫花苜蓿对盐胁迫的响应，为后续紫花苜蓿耐盐分子育种提供了理论依据。

关键词: 紫花苜蓿, MsSPL3, 耐盐, 功能验证