目的 对女贞Ligustrum lucidum UDP-糖基转移酶（UDP-glycosyltransferase，UGT）基因家族进行系统鉴定，并分析UGT75亚家族在成熟果实不同采收时期的表达模式，为解析女贞环烯醚萜苷类成分生物合成机制及相关功能基因挖掘提供基础。方法 基于女贞基因组数据，采用保守结构域检索、系统发育分析等多种生物信息学方法对女贞UGT基因家族成员进行系统鉴定，并分析其理化性质、亚细胞定位、基因结构、保守基序、染色体定位及共线性关系；结合逆转录实时荧光定量PCR分析（reverse transcription quantitative PCR，RT-qPCR）与公开的代谢组数据，分析LlUGT75亚家族候选基因在成熟果实不同采收时期的表达模式，并探讨其表达水平与环烯醚萜类化合物积累的相关性。结果 女贞全基因组中共鉴定获得UGT基因家族成员197个，分为12个亚家族，其中UGT75亚家族包含12个成员。LlUGT75亚家族蛋白多表现为弱酸性、亲水性且体外可能不稳定，具有多样化的亚细胞定位特征；其基因结构和保守基序较为保守，普遍含有C端PSPG相关基序。LlUGT基因在染色体上分布不均，部分基因可能与复制扩张有关。RT-qPCR结果显示，LlUGT75亚家族候选基因在成熟果实不同采收时期呈差异表达；结合代谢组相关性分析，Llu21G013200.1与木樨榄苷-11-甲酯、女贞苷、橄榄苦苷及特女贞苷的积累趋势较为一致；基因共表达网络分析表明LlUGT75候选基因与环烯醚萜生物合成通路基因之间存在一定的表达协同关系，其中Llu14G003660.1表现出较为紧密的网络连接特征。结论 女贞UGT基因家族结构较为保守，其扩张可能与基因复制事件有关。LlUGT75亚家族成员在成熟果实不同采收时期呈差异表达，提示其可能发生功能分化，并可能与环烯醚萜苷类成分积累有关。为女贞UGT功能基因挖掘及主要活性成分生物合成机制解析提供参考。

Objective To systematically identify the UDP-glycosyltransferase (UGT) gene family in Ligustrum lucidum and analyze the expression patterns of the UGT75 subfamily in mature fruits at different harvest stages, so as to provide a basis for elucidating the biosynthetic mechanism of iridoid glycosides in L. lucidum and mining related functional genes. Methods Based on the genome data of L. lucidum, members of the UGT gene family were systematically identified using bioinformatics methods, including conserved domain search and phylogenetic analysis. Their physicochemical properties, subcellular localization, gene structures, conserved motifs, chromosomal localization and collinearity relationships were further analyzed. Combined with reverse transcription quantitative PCR (RT-qPCR) and public metabolomic data, the expression patterns of LlUGT75 candidate genes in mature fruits at different harvest stages were analyzed, and the correlation between their expression levels and the accumulation of iridoid compounds was explored. Results A total of 197 UGT gene family members were identified from the whole genome of L. lucidum and classified into 12 subfamilies, among which the UGT75 subfamily contained 12 members. Most LlUGT75 proteins were weakly acidic, hydrophilic and possibly unstable in vitro, and exhibited diverse subcellular localization patterns. Their gene structures and conserved motifs were relatively conserved, with a conserved C-terminal PSPG-related motif commonly identified. LlUGT genes were unevenly distributed on chromosomes, and the expansion of some members might be related to gene duplication events. RT-qPCR results showed that LlUGT75 candidate genes were differentially expressed in mature fruits at different harvest stages. Combined with metabolomic correlation analysis, the expression trend of Llu21G013200.1 was relatively consistent with the accumulation trends of oleoside 11-methyl ester, ligustroside, oleuropein and specnuezhenide. In addition, gene co-expression network analysis revealed a certain degree of expression coordination between LlUGT75 candidate genes and genes involved in the iridoid biosynthetic pathway, in which Llu14G003660.1 exhibited relatively strong network connectivity. Conclusion The UGT gene family in L. lucidum is relatively conserved in structure, and its expansion may be associated with gene duplication events. LlUGT75 subfamily members show differential expression in mature fruits at different harvest stages, suggesting that they may have undergone functional differentiation and may be related to the accumulation of iridoid glycosides. This study provides a reference for mining functional UGT genes and elucidating the biosynthetic mechanism of major active components in L. lucidum.

R282.12

南京中医药大学中药学一流学科“引领计划”科学研究专项（ZYXYL2024-02）；吴啟南全国老药工传承工作室课题（2025）