Sugar beet is an important sugar crop, and its roots are mainly used for processing raw materials to produce products such as sugar, molasses, and saccharin, as well as being used as fodder for livestock. BvCPD, a key enzyme gene for brassinosteroid (BR) synthesis, regulates the development of parenchyma cells and vascular bundles by promoting BR synthesis, which promotes the expansion of the sugar beet taproot and influences the growth, development, and yield of sugar beets. This study investigated the impact of BvCPD on the physiological metabolism of sugar beet utilizing BvCPD overexpression, silent, and wild-type (WT) lines. BvCPD increased the chlorophyll content and maximum photochemical efficiency and improved the photosynthetic characteristics of sugar beet leaves. Simultaneously, BvCPD increased the rate of sugar beet taproot respiration and ATP content by enhancing the activities of phosphoglycerate kinase, alcohol dehydrogenase, sucrose synthase, and sucrose synthase catabolism. Moreover, BvCPD induced changes in the sugar fraction content, which increased the sugar yield of a single plant. In addition, BvCPD promoted water absorption, nitrogen accumulation, and lignin/cellulose synthesis activities, facilitated by increased activities of phenylalanine ammonia-lyase, cinnamyl alcohol dehydrogenase, cellulose synthase, and protein serine/threonine phosphatases, providing the requisite energy and materials for sugar beet growth. These findings not only provide a new perspective for understanding the physiological mechanisms regulating the growth of sugar beets but also provide a theoretical basis for the future improvement of sugar beet varieties through molecular breeding techniques.

Sugar beet cytoplasmic male sterility (CMS) underpins hybrid seed production, yet the contribution of protein phosphorylation remains unexplored. Using 4D label-free phosphoproteomics on anthers of the Owen-type CMS line MS327 and its maintainer OT328 at the 2–3 mm bud stage, we identified 1241 phosphoproteins, 1975 phosphopeptides and 3357 phosphosites, of which 469 proteins and 848 sites were quantifiable. Twenty-one phosphopeptides exhibited significant differential abundance (fold change > 2.0, p < 0.05; 3 up, 18 down), while 69 and 141 peptides were detected exclusively in the maintainer and the sterile line, respectively. Pathway enrichment implicated the spliceosome and fatty acid elongation pathways in male sterility. Integrating KEGG, GO and predicted protein–protein interaction networks analyses, we identified nuclear cap-binding protein subunit 2 (NCBP2), the RRM-containing splicing factor SR45a and 3-ketoacyl-CoA synthase as candidate phosphoproteins associated with male sterility. All six core proteins were deeply conserved across the examined species. Although transcript levels of the six corresponding genes did not differ significantly between the two lines in either leaf or anthers, anther phosphorylation levels did, pointing to post-translational rather than transcriptional control. This first phosphoproteomic survey of sugar beet CMS provides a valuable readout of post-translational reprogramming and offers promising candidate targets for future functional validation.