Regulation and functional analysis of BvMBF1c in response to Cercospora leaf spot (CLS) stresses in sugar beet (Beta vulgaris L.)

The Multiprotein Bridging Factor 1 (MBF1) gene family, a conserved transcriptional coactivator central to plant stress adaptation, has been systematically characterized in this study across diverse species, including the economically critical crop sugar beet (Beta vulgaris L.). Phylogenetic analysis delineated two evolutionarily distinct clades: Group I (MBF1a/b) with conserved exon-intron structures and Group II (MBF1c) exhibiting intron-poor architectures, a feature linked to rapid transcriptional activation under stress. In sugar beet, BvMBF1c demonstrated nuclear localization and pathogen-responsive expression dynamics, peaking within 48 h post-Cercospora beticola (C. beticola) inoculation. Yeast two-hybrid assays confirmed a novel interaction between BvMBF1c and trehalose-6-phosphate synthase (TPS5), implicating its role in osmotic regulation through trehalose biosynthesis—a mechanism critical for mitigating pathogen-induced cellular stress. Synteny and collinearity analyses revealed lineage-specific duplication events, underscoring the role of genomic plasticity in stress adaptation. Notably, MBF1c homologs displayed conserved microsynteny in woody perennials (Populus trichocarpa, Citrus sinensis) but diverged in monocots, reflecting adaptive evolution to species-specific environmental pressures. This study integrates evolutionary, structural, and functional insights to position MBF1c as a molecular hub bridging transcriptional regulation with metabolic homeostasis, offering actionable targets for breeding climate-resilient crops. Our findings highlight BvMBF1c as a candidate for enhancing disease resistance in sugar beet, with broader implications for improving stress tolerance in agronomically vital species.