Abstract: Phytochrome A （phyA） is a key receptor that enables plants to perceive far-red light signals and regulates their growth， development， and stress responses. To investigate the function of the MsphyA gene and its molecular mechanism in response to abiotic stress in alfalfa （Medicago sativa L.）， this study conducted a bioinformatic analysis of the cloned MsphyA gene and detected its expression patterns under various abiotic stresses using qRT-PCR. Bioinformatic analysis revealed that the MsphyA gene has a CDS length of 3375 bp， encoding 1124 amino acids， and possesses typical PAS， GAF， and PHY motifs characteristic of the PHY family. Protein analysis indicated that MsphyA has a relative molecular mass of 124.3 kDa and a theoretical isoelectric point of 6.1. It is classified as an unstable， hydrophilic， non-secretory protein without a signal peptide and lacks transmembrane domains. Subcellular localization prediction suggested that MsphyA is localized to the nucleus. Phylogenetic analysis showed that MsphyA is most closely related to MtphyA from M. truncatula. qRT-PCR results demonstrated that salt， drought， acid， high-temperature， and low-temperature stresses all induced MsphyA expression. These findings indicate that MsphyA is widely involved in the abiotic stress responses in alfalfa. This study provides a foundation for further exploration of the MsphyA gene’s function.

Key words: Alfalfa, phyA, Bioinformatics analysis, Abiotic stress

摘要： 光敏色素A（phyA）是植物感知远红光信号并调控生长发育及逆境应答的关键受体。为探究MsphyA基因功能及其在紫花苜蓿（Medicago sativa L.）中响应非生物胁迫的分子机制，本研究对已克隆的MsphyA基因全长质粒进行测序鉴定及完整结构域生物信息学分析，并通过qRT-PCR技术检测该基因在不同非生物胁迫下的表达模式。生物信息学分析显示MsphyA基因编码序列（Coding sequence，CDS）区全长3375 bp，编码1124个氨基酸，具有典型的PHY家族的PAS，PHY和GAF motifs特殊结构域；蛋白分析显示其相对分子量为124.3 kDa，理论等电点为6.1，属于不含信号肽的非分泌不稳定亲水性蛋白且不具备跨膜结构；亚细胞定位预测该蛋白定位于细胞核；系统进化树表明MsphyA蛋白与蒺藜苜蓿MtphyA亲缘关系最近。qRT-PCR结果表明，盐、干旱、酸、高温、低温处理均能诱导MsphyA的表达，MsphyA广泛参与紫花苜蓿的非生物胁迫应答过程，本研究为进一步探究紫花苜蓿MsphyA基因功能提供了参考。

关键词: 紫花苜蓿, phyA, 生物信息学分析, 非生物胁迫