Genome-wide identification and expression analysis of the PtrUGT gene family in Populus trichocarpa

UDP-glycosyltransferases (UGTs) were widely distributed in plants and played crucial roles in mediating glycosylation reactions associated with metabolic pathways. Although UGT gene families have been characterized in various species, a comprehensive analysis in Populus trichocarpa remained to be fully elucidated. In this study, 204 PtrUGT genes were identified through genome-wide analysis, revealing significant variations in protein length, molecular weight, and isoelectric point. Chromosomal mapping revealed an uneven distribution across all 19 chromosomes, with chr16 exhibiting the highest gene density. Furthermore, tandem duplication events were identified as the primary drivers of gene family expansion. Synteny analysis highlighted extensive gene duplication, resulting in 266 paralogous gene pairs, and revealed closer evolutionary ties to Eucalyptus robusta with 74 orthologous gene pairs, compared to Arabidopsis thaliana and Oryza sativa . Phylogenetic classification grouped the PtrUGTs into 19 distinct subgroups (A-S), with subgroup-specific motif conservation and gene structures. Promoter analysis uncovered abundant cis -regulatory elements associated with light, methyl jasmonate, abscisic acid, and stress responses, indicating functional diversification among the PtrUGT genes. Both RNA-seq and quantitative real-time PCR (qRT-PCR) analyses revealed tissue-specific expression patterns and stress-responsive regulation, with certain PtrUGTs showing significant induction under drought, salt stress, or insect herbivory stress. Subcellular localization analysis revealed that the stress-responsive PtrUGT198 is present in both the nucleus and the cytoplasm. This study provides a systematic characterization of the PtrUGT family, offering valuable insights for identifying genes related to stress resistance and facilitating molecular breeding strategies in poplar.