Identification of BvUGT90 Family Members and Analysis of Drought Resistance Gene Screening in Sugar Beet

The sugar beet (<i>Beta vulgaris</i> L.) industry in China occupies a pivotal position in the national sugar supply, yet drought in its major cultivation areas has become a key limiting factor for its high-quality development. Glycosyltransferases (GTs) play a pivotal role in plant responses to abiotic stress, particularly in the regulation of drought resistance. However, the systematic identification of the <i>BvUGT90</i> gene family in sugar beet and the functional characterization of its members under drought stress remain largely unexplored. In this study, drought stress was simulated in the sugar beet cultivar 'HI0466' using the weighing method to regulate soil moisture. Samples were collected at different stress durations and after rewatering for subsequent experimental analyses. In this study, 121 members of the <i>BvUGT90</i> family were identified in sugar beet, and a comprehensive analysis was conducted on their gene structures, phylogenetic relationships, promoter cis-acting elements and expression patterns under drought stress. The results showed that these 121 members were unevenly distributed across 9 chromosomes. The proteins they encode had an average amino acid length of 474, with molecular weights ranging from 10.78 to 99.10 kDa and theoretical isoelectric points (pI) from 4.68 to 8.69 (with an average of 5.76). Notably, 110 of these members (accounting for 90.91%) were identified as hydrophilic proteins. Synteny analysis indicated a high degree of homology between the <i>BvUGT90</i> family members in sugar beet and their orthologous genes in <i>Arabidopsis thaliana</i>. Analysis of promoter cis-acting elements revealed the presence of six major categories of core elements in the promoter regions of <i>BvUGT90</i> genes, including hormone-responsive elements, stress-responsive elements and pathway regulatory elements. Transcriptomic data showed that 45 <i>BvUGT90</i> family members exhibited significant responsiveness to drought stress. Proteomic analysis demonstrated that 10 of these members were significantly upregulated at the protein level under drought stress, and these results were further validated by quantitative real-time polymerase chain reaction (qRT-PCR). Integrated transcriptomic and proteomic analyses identified <i>Bv_005070_jjst.t1</i> and <i>Bv6_140060_stjc.t1</i> as the family members with the most prominent responses to drought stress. Furthermore, transgenic transformation of sugar beet was performed, which confirmed that <i>Bv_005070_jjst.t1</i> plays an important role in drought stress resistance. The findings of this study provide direct candidate genes from this family for drought-tolerant sugar beet breeding.