HE Holtan, S Bandong, CM Marion, L Adam, et al. Plant Physiology, 2011.
A B-box zinc finger protein, B-BOX32 (BBX32), was identified as playing a role in determining hypocotyl length during a large-scale functional genomics study. Further analysis revealed that seedlings over expressing BBX32 display elongated hypocotyls in red, far-red and blue light, along with reduced cotyledon expansion in red light. Through comparative analysis of mutant and over expression line phenotypes, including global expression profiling and growth curve studies, we demonstrate that BBX32 acts antagonistically to HY5. We further show that BBX32 interacts with STH2, another Bbox protein previously shown to interact with HY5. Based on these data, we propose that BBX32 functions downstream of multiple photoreceptors as a modulator of light responses. As such, BBX32 potentially has a native role in mediating gene repression to maintain dark adaptation… AR75L chamber (Percival) was used for white light. Fluence rates were measured using a spectroradiometer (EPP2000-VIS-50, StellarNet Inc). Hypocotyl and cotyledon area measurements were performed using digital images (Canon G9) analyzed with Image J. View PDF.
Fig. 1. Simplified model depicting a functional role of BBX32 in photomorphogenesis. The hypothetical model indicates that BBX32 interacts with STH2 and suppresses the activities of positive factors, STH2 and HY5, involved in photomorphogenesis that control multiple aspects of seedling de-etiolation, including light-regulated gene expression and cell expansion.
