B-Box (BBX) proteins and transcriptional regulation: dynamics, signaling and functions in plants

Transcriptional regulation is the cornerstone of plant developmental plasticity and environmental resilience. Central to these processes are the B-Box (BBX) proteins, a family of zinc-finger transcription factors that have emerged as pivotal signaling hubs. While their roles were initially defined through light signaling and photoperiodic flowering in Arabidopsis, recent advances have repositioned BBX proteins as integrative nodes across a vast array of physiological processes, including seed germination, thermomorphogenesis, shade avoidance and senescence, as well as responses to both abiotic and biotic stresses. The remarkable functional diversity of BBX proteins emerges from a highly orchestrated, hierarchical regulatory landscape. This review synthesizes recent progress in how BBX activity is modulated through chromatin remodeling, alternative splicing and E3-ligase-mediated protein stability, among other mechanisms. We propose that understanding BBX function requires a shift from identifying isolated target genes to decoding the combinatorial logic of their interactions. Deciphering this interactome under fluctuating environments not only deepens our knowledge of the molecular mechanisms regulating plant plasticity but also identifies highly promising targets for the precision breeding of climate-resilient crops.