title: The transcriptional regulator BBX24 impairs DELLA activity to promote shade avoidance in Arabidopsis thaliana.
abstract: In response to canopy shade, plant vegetative structures elongate to gain access to light. However, the mechanism that allows a plastic transcriptional response to canopy shade light is not fully elucidated. Here we propose that the activity of PIF4, a key transcription factor in the shade signalling network, is modulated by the interplay between the BBX24 transcriptional regulator and DELLA proteins, which are negative regulators of the gibberellin (GA) signalling pathway. We show that GA-related targets are enriched among genes responsive to BBX24 under shade and that the shade-response defect in bbx24 mutants is rescued by a GA treatment that promotes DELLA degradation. BBX24 physically interacts with DELLA proteins and alleviates DELLA-mediated repression of PIF4 activity. The proposed molecular mechanism provides reversible regulation of the activity of a key transcription factor that may prove especially relevant under fluctuating light conditions.
authors: IFEVA, Facultad de Agronomía, Universidad de Buenos Aires y Consejo Nacional de Investigaciones Científicas y Técnicas, Avenue San Martín 4453, Buenos Aires C1417DSE, Argentina.
authors: Carlos D
authors: CD
authors: Crocco
authors: 1] Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, Valencia 46022, Spain [2] Department of Agronomy, Food, Natural Resources, Animals and the Environment (DAFNAE), Padova University, Viale dell'Universitá 16, Legnaro 35020, Italy.
authors: Antonella
authors: A
authors: Locascio
authors: IFEVA, Facultad de Agronomía, Universidad de Buenos Aires y Consejo Nacional de Investigaciones Científicas y Técnicas, Avenue San Martín 4453, Buenos Aires C1417DSE, Argentina.
authors: Cristian M
authors: CM
authors: Escudero
authors: Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, Valencia 46022, Spain.
authors: David
authors: D
authors: Alabadí
authors: Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, Valencia 46022, Spain.
authors: Miguel A
authors: MA
authors: Blázquez
authors: IFEVA, Facultad de Agronomía, Universidad de Buenos Aires y Consejo Nacional de Investigaciones Científicas y Técnicas, Avenue San Martín 4453, Buenos Aires C1417DSE, Argentina.
authors: Javier F
authors: JF
authors: Botto
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000502:physiology* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000378:metabolism*; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000528:radiation effects; D017343:Genes, Plant; D005875:Gibberellins / Q000494:pharmacology; D018546:Hypocotyl / Q000033:anatomy & histology / Q000187:drug effects / Q000528:radiation effects; D008027:Light; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D010846:Picloram / Q000494:pharmacology; D010937:Plant Growth Regulators / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects / Q000528:radiation effects; D012097:Repressor Proteins / Q000378:metabolism*; D014026:Nicotiana / Q000378:metabolism; D015534:Trans-Activators / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
chemical_list: D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D005875:Gibberellins; D010846:Picloram; D010937:Plant Growth Regulators; D012097:Repressor Proteins; D015534:Trans-Activators; C585246:BBX24 protein, Arabidopsis; C109555:GAI protein, Arabidopsis; C459466:PIF4 protein, Arabidopsis