Regulatory Mechanisms of BBX Transcription Factors

Plants frequently encounter abiotic stresses such as drought, cold, and high light, which severely reduce crop yields. B-box (BBX) transcription factors are emerging as central regulators that link light signalling to stress responses, but their global regulatory networks remain poorly defined. This review synthesises evidence from Arabidopsis and major crops, including tomato, rice, apple, and tobacco, drawing on gene expression analyses, mutant phenotyping, protein interaction assays, and ubiquitination studies. The compiled results show that BBX proteins act as either positive or negative modulators depending on species and stress type. They control stress tolerance by physically interacting with partners like HY5 and PIFs, directly regulating downstream target genes, and undergoing COP1- or MIEL1-mediated proteasomal degradation. Notably, the C-terminal region dictates their functional divergence, as confirmed by domain-swapping experiments. These findings establish BBX proteins as versatile hubs that integrate environmental cues with developmental programmes. The conclusions suggest that precise manipulation of specific BBX members or their regulatory domains offers a viable route to enhance broad-spectrum stress resilience in crops, supporting sustainable food production under changing climates.