Arabidopsis BOR transporters and their regulation under boron toxicity

In Arabidopsis thaliana, the BOR transporter family (AtBOR1–AtBOR7) mediates boron efflux, long-distance transport, and stress responses; however, the functional differentiation and regulatory mechanisms among these transporters remain poorly understood. This study comprehensively characterizes the AtBor gene family through integrated structural, phylogenetic, gene expression, and protein interaction analyses. Phylogenetic analysis divided the seven AtBOR proteins into three distinct clades, indicating evolutionary diversification. Expression profiling under varying boron concentrations and abiotic stress conditions revealed constitutive or moderate expression of AtBOR1, AtBOR2, and AtBOR3 across tissues, suggesting conserved functions in maintaining basal boron homeostasis. Conversely, AtBOR4–AtBOR7 showed low or stress-responsive expression patterns, with notable induction of AtBOR3 in shoots under cold stress, indicating its potential role in boron redistribution during abiotic stress adaptation. Subcellular localization analyses predicted predominant plasma membrane targeting for most AtBOR transporters, while protein–protein interaction studies implicated several members in vesicle trafficking, stress signaling, and detoxification pathways. This study represents the first systematic characterization of all seven AtBOR genes under boron toxicity, providing novel insights into their functional specialization and regulatory dynamics. The results presented here significantly enhance our understanding of boron transporter diversity, laying the foundation for future development of crop varieties with improved micronutrient use efficiency and enhanced resilience to environmental stresses.