Abstract: Uridine diphosphate (UDP)-glycosyltransferase (UGT) catalyzes the glycosylation of secondary metabolites such as flavonoids in plants,which plays important roles in plant resistance to various stresses. In this study,an UGT family gene MsUGT87A1 was cloned from alfalfa. The physicochemical properties,secondary structure and subcellular localization of MsUGT87A1 protein were analyzed by bioinformatics. The tissue-specific expression pattern of MsUGT87A1 gene and its response to different abiotic stresses were investigated by fluorescence quantitative real-time PCR. The results showed that the full-length of MsUGT87A1 gene was 1 353 bp,encoding 450 amino acids. The relative molecular weight of MsUGT87A1 was 50.98 kDa,and the theoretical isoelectric point (pI) was 5.78. The MsUGT87A1 protein was mainly located in cytoplasm. Phylogenetic tree results showed that the MsUGT87A1 in alfalfa had a high homology with the UGT87A1 in Medicago truncatula and Trifolium pratense. The expression of MsUGT87A1 gene was highest in the roots of alfalfa and positively responded to drought,salt and ABA treatments. It was preliminarily determined that the MsUGT87A1 gene was involved in response to drought and salt stresses of alfalfa. This study laid a foundation for the further exploring the function of MsUGT87A1 gene and provided a theoretical basis for genetic improvement of stress resistance of alfalfa.

Key words: Alfalfa, Glycosyltransferase, MsUGT87A1, Gene cloning, Expression pattern

摘要： 尿苷二磷酸(Uridine diphosphate，UDP)糖基转移酶(UDP-glycosyltransferase，UGT)催化植物体内黄酮等次生代谢产物的糖基化反应，在植物抵御逆境胁迫过程中具有重要作用。本研究从紫花苜蓿(Medicago sativa)中克隆UGT家族基因MsUGT87A1，利用生物信息学方法对其蛋白质理化性质、二级结构和亚细胞定位等进行分析，并通过荧光定量PCR分析MsUGT87A1基因的组织表达特异性及对不同非生物胁迫的响应情况。结果表明，MsUGT87A1基因全长1 353 bp，编码450个氨基酸，蛋白质相对分子量为50.98 kDa，理论等电点(pI)为5.78，属于亲水性蛋白，主要定位于细胞质中。系统进化树结果表明紫花苜蓿MsUGT87A1与蒺藜苜蓿、红三叶等豆科植物的UGT87A1同源性较高。MsUGT87A1基因在紫花苜蓿根中表达量最高，对干旱、盐和ABA处理均有响应，初步确定MsUGT87A1基因参与紫花苜蓿应对干旱及盐胁迫响应。该研究为进一步探究MsUGT87A1基因功能奠定基础，为紫花苜蓿抗逆性遗传改良提供理论依据。

关键词: 紫花苜蓿, 糖基转移酶, MsUGT87A1, 基因克隆, 表达模式