Identification of BBX proteins as rate-limiting cofactors of HY5.

As a source of both energy and environmental information, monitoring of incoming light is crucial for plants to optimize growth throughout development. Concordantly, the light signalling pathways in plants are highly integrated with numerous other regulatory pathways. One of these signal integrators is the basic leucine zipper domain (bZIP) transcription factor LONG HYPOCOTYL 5 (HY5), which has a key role as a positive regulator of light signalling in plants.

Degradation of the transcription factors PIF4 and PIF5 under UV-B promotes UVR8-mediated inhibition of hypocotyl growth in Arabidopsis.

Inhibition of hypocotyl growth is a well-established UV-B-induced photomorphogenic response that is mediated by the UV-B photoreceptor UV RESISTANCE LOCUS 8 (UVR8). However, the molecular mechanism by which UVR8 signaling triggers inhibition of hypocotyl growth is poorly understood. The bZIP protein ELONGATED HYPOCOTYL 5 (HY5) functions as the main positive regulatory transcription factor in the UVR8 signaling pathway, with HY5-HOMOLOG (HYH) playing a minor role.

RUP2 represses UVR8-mediated flowering in noninductive photoperiods.

Plants have evolved complex photoreceptor-controlled mechanisms to sense and respond to seasonal changes in day length. This ability allows plants to optimally time the transition from vegetative growth to flowering. UV-B is an important part intrinsic to sunlight; however, whether and how it affects photoperiodic flowering has remained elusive.

Regulation of MYB and bHLH transcription factors: a glance at the protein level.

In complex, constantly changing environments, plants have developed astonishing survival strategies. These elaborated strategies rely on rapid and precise gene regulation mediated by transcription factors (TFs). TFs represent a large fraction of plant genomes and among them, MYBs and basic helix-loop-helix (bHLHs) have unique inherent properties specific to plants.