The sugar beet (Beta vulgaris 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 BvUGT90 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 BvUGT90 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 BvUGT90 family members in sugar beet and their orthologous genes in Arabidopsis thaliana. Analysis of promoter cis-acting elements revealed the presence of six major categories of core elements in the promoter regions of BvUGT90 genes, including hormone-responsive elements, stress-responsive elements and pathway regulatory elements. Transcriptomic data showed that 45 BvUGT90 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 Bv_005070_jjst.t1 and Bv6_140060_stjc.t1 as the family members with the most prominent responses to drought stress. Furthermore, transgenic transformation of sugar beet was performed, which confirmed that Bv_005070_jjst.t1 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.

Soil salinity restricts sugar beet growth and productivity, creating a need for effective agronomic approaches to improve plant performance under salt-affected conditions. However, the comparative responses of sugar beet to different foliar-applied exogenous substances under controlled NaCl stress and field saline–alkali conditions remain insufficiently understood. In this study, sugar beet (Beta vulgaris L.) cultivar ‘HI0479’ was used to evaluate the effects of different concentrations of PAA@Mn₃O₄ nanoparticles (PMO), methyl jasmonate (MeJA), and γ-aminobutyric acid (GABA). A pot experiment was first conducted under controlled NaCl stress to identify concentrations for subsequent field evaluation, followed by a one-season field experiment under non-saline–alkali and saline–alkali soil conditions. Based on the overall responses of growth and physiological traits, 100 mg L⁻¹ PMO, 100 mg L⁻¹ MeJA, and 1000 mg L⁻¹ GABA were selected for field evaluation. Under the imposed NaCl treatment, these foliar treatments improved growth and physiological performance and were associated with changes in photosynthetic characteristics, antioxidant enzyme activities, MDA content, osmolyte accumulation, and selected growth-related hormone levels. Under saline–alkali field conditions, PMO, MeJA, and GABA increased storage-root yield by 13.59%, 12.69%, and 12.37%, respectively, compared with the control. Although estimated storage-root sugar concentration decreased, the corresponding estimated sugar yields increased by 10.77%, 9.79%, and 7.41%, respectively. These results show that the three foliar treatments produced favorable growth- and yield-related responses under the experimental conditions evaluated while also revealing a trade-off between storage-root yield and estimated storage-root sugar concentration. The findings provide a basis for further agronomic evaluation of foliar PMO, MeJA, and GABA in sugar beet grown under salt-affected conditions.

Sugar beet (Beta vulgaris L.) is an important economic crop and a primary source of sugar in northern China, characterized by strong stress tolerance and high nutritional value. Microbial inoculants can promote crop growth by regulating soil enzyme activities, enriching dominant beneficial bacterial genera in rhizosphere soil, and improving the availability of soil nutrients. This study aimed to investigate the role of microbial inoculants in sugar beet production and their potential to replace chemical fertilizers and put forward the scientific hypothesis that microbial inoculants can increase soil nutrients and improve the soil microenvironment. A two-year field experiment was conducted: in 2022, treatments with different application rates of Bacillus subtilis and Trichoderma spp. inoculants were set up to screen the optimal inoculant and its dosage (M1); in 2023, based on this optimal inoculant (M1), treatments with reduced chemical fertilizer input were established to explore the mechanisms underlying the maintenance of sugar beet yield and quality. The results showed that the M1N2 (75 kg/ha fertilizer and 20% less nitrogen fertilizer) treatment significantly increased nitrogen, phosphorus, and potassium agronomic use efficiencies by 91.48%, 51.94%, and 53.50%, respectively, compared with the control (CK). Soil urease, catalase, and sucrase activities were significantly enhanced by 14.57%, 66.84%, and 222.46%, respectively. The treatment also significantly increased the relative abundance of beneficial bacterial genera such as JG30-KF-CM45 and KD4-96, while sugar beet yield was significantly increased by 5.53% relative to the CK. This study provides a theoretical basis for the application of microbial inoculants and the reduction in chemical fertilizers in sugar beet production.