Abstract：Uridine diphosphate glycosyltransferases(UGT) are a class of key enzymes in plants, which are widely involved in physiological processes such as secondary metabolism, hormone balance, and stress response. However, current research on the functions of UGT genes in rice(Oryza sativa) remains insufficient. To explore the mechanism of UGT genes in rice growth and development as well as abiotic stress response, this study comprehensively analyzed the rice UGT family using bioinformatics methods. Meanwhile, combined with qPCR technology, the expression patterns of the OsUGT79 gene in different tissues under 4 abiotic stresses were further investigated. A total of 165 UGT genes were identified in rice. The length of the proteins encoded by these genes ranged from 113 to 772 aa, with a molecular weight of 12.53~83.65 kD. Most of these proteins were acidic(95.2%), hydrophilic(50.3%), and structurally stable(75.2%). These genes were unevenly distributed on 12 chromosomes, and the promoter regions were rich in cis-acting elements related to abiotic stress response, growth and development, and hormone regulation. Subcellular localization prediction showed that UGT proteins were mainly located in chloroplasts(57%) and cytoplasm(24.8%). Phylogenetic analysis divided these UGT genes into 3 major groups and 6 subgroups(Group Ⅰ~Group Ⅵ), among which Group Ⅰ and Group Ⅱ belonged to the 1st and 2nd major groups respectively, while Group Ⅲ~Group Ⅵ were classified into the 3rd major group. Conserved motif analysis revealed that 85% of UGT proteins contained the GTB-type superfamily domain. Collinearity analysis results indicated that there were 10 pairs of segmentally duplicated genes and 2 pairs of tandemly duplicated genes in this family. The representative protein OsUGT79 comprised 422 aa with a molecular mass of 51.03 kD, which was acidic, hydrophilic and structurally stable. The gene was localized on chromosome 4, belongs to subgroup Ⅵ of the 3rd major group, and was predicted to be located in chloroplasts. qPCR analysis showed that, under high temperature, drought and cadmium stress, the expression of OsUGT79 in shoots rose rapidly and then declined, with peaks at 12 h for high temperature and cadmium stress at 6 h for drought; under salt stress, shoot expression dropped sharply and remained low. In roots, the expression of OsUGT79 increased markedly from 6 h and continued to rise, reaching maximum at 24 h for all stresses except salt. After a 48 h recovery, shoot expression exceeded all stress-time maxima(except under cadmium), whereas root levels fell below the stress peaks and even below pre-stress values. Moreover, the magnitude of change was consistently greater in roots than in shoots, indicating that OsUGT79 mainly participated in early stress perception and initial responses in roots, while contributing to post-stress physiological recovery in shoot tissues. This study provides the first comprehensive portrait of the rice UGT family's composition and evolutionary characteristics, laying a theoretical foundation for elucidating the functions of OsUGT79 and other UGT members in abiotic stress adaptation and offering valuable insights for molecular breeding of stress-resilient rice.
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