Table_4_Genome-wide identification, characterization, and expression analysis of UDP-glycosyltransferase genes associated with secondary metabolism in alfalfa (Medicago sativa L.).XLSX

Uridine diphosphate glycosyltransferases (UGTs) are enzymes that catalyze glycosylation modifications and play an essential role in regulating plant metabolism. Alfalfa (Medicago sativa L.) is the most important legume in the world due to its high yields and protein content; however, the UGT genes in alfalfa have not yet been studied. Identifying UGT genes with metabolic roles in alfalfa is essential for identifying and modifying genetic traits that are relevant to yield and quality. In this study, 90 of the 239 UGT genes identified from the alfalfa “Zhongmu No. 1” genome database were found to be related to secondary metabolism, and a series of gene family characterization analyses were conducted on each. The results demonstrated that all 90 UGT genes were unevenly distributed on eight chromosomes with few introns and that tandem duplications were the crucial driving force expanding the UGT family in alfalfa. Notably, the 90 UGT genes can be clustered into ten evolutionary groups which contain specific PSPG motifs, and genes in these ten groups have specific tissue expressions. This suggests that the UGT genes in each group could have similar glycosylation roles corresponding to analogous secondary metabolites in alfalfa. Additionally, multiple cis-acting elements found in MsUGT promoter regions, such as phytohormone and flavonoids, indicate that 90 UGT members could be induced by these features, which are also related to secondary metabolism. Therefore, our study identified 90 UGT members inten evolutionary groups that are likely related to glycosylation modifications with secondary metabolites in alfalfa. These findings help uncover pivotal regulatory mechanisms associated with secondary metabolism in plant yield and quality and contribute to genetic modification and breeding in alfalfa and other plant species.

尿苷二磷酸糖基转移酶（Uridine diphosphate glycosyltransferases, UGTs）是一类催化糖基化修饰的酶，在调控植物代谢过程中发挥关键作用。紫花苜蓿（Medicago sativa L.）因高产且蛋白质含量丰富，是全球最重要的豆科植物；然而目前尚未针对紫花苜蓿中的UGT基因开展系统性研究。鉴定紫花苜蓿中参与代谢调控的UGT基因，对于识别并改良与产量和品质相关的遗传性状具有重要意义。本研究从紫花苜蓿‘中苜1号’基因组数据库中鉴定出的239个UGT基因中，有90个与次生代谢相关，并针对这90个基因开展了一系列基因家族特征分析。结果显示，这90个UGT基因均不均匀分布于8条染色体上，且内含子数量普遍较少；串联重复事件是驱动紫花苜蓿UGT基因家族扩张的关键动力。值得注意的是，这90个UGT基因可被划分为10个进化类群，每个类群均包含特异的PSPG基序，且不同类群的基因呈现出特异性的组织表达谱。这表明每个类群中的UGT基因可能具有相似的糖基化功能，对应紫花苜蓿中结构或功能类似的次生代谢产物。此外，在MsUGT基因的启动子区域中鉴定到多种顺式作用元件，包括植物激素响应元件与类黄酮响应元件等，提示这90个UGT成员可受这些与次生代谢相关的因素诱导。因此，本研究共鉴定出隶属于10个进化类群的90个UGT成员，它们可能参与紫花苜蓿中次生代谢物的糖基化修饰过程。本研究结果有助于揭示植物产量与品质相关的次生代谢调控关键机制，同时可为紫花苜蓿及其他植物物种的遗传改良与分子育种工作提供理论参考。