DELLA transcriptional regulators are central components in the control of plant growth responses to the environment. This control is considered to be mediated by changes in the metabolism of the hormones gibberellins (GAs), which promote the degradation of DELLAs. However, here we show that warm temperature or shade reduced the stability of a GA-insensitive DELLA allele in Arabidopsis thaliana Furthermore, the degradation of DELLA induced by the warmth preceded changes in GA levels and depended on the E3 ubiquitin ligase CONSTITUTIVELY PHOTOMORPHOGENIC1 (COP1). COP1 enhanced the degradation of normal and GA-insensitive DELLA alleles when coexpressed in Nicotiana benthamiana. DELLA proteins physically interacted with COP1 in yeast, mammalian, and plant cells. This interaction was enhanced by the COP1 complex partner SUPRESSOR OF phyA-105 1 (SPA1). The level of ubiquitination of DELLA was enhanced by COP1 and COP1 ubiquitinated DELLA proteins in vitro. We propose that DELLAs are destabilized not only by the canonical GA-dependent pathway but also by COP1 and that this control is relevant for growth responses to shade and warm temperature.

Departamento de Genética Molecular de Plantas Centro Nacional de Biotecnología Consejo Superior de Investigaciones Cientίficas 28049 Madrid Spain

Department of Molecular Biology and Radiobiology Central European Institute of Technology Faculty of AgriSciences Mendel University in Brno CZ 61300 Brno Czech Republic

Department of Neurology Keck School of Medicine University of Southern California Los Angeles CA 90098

Department of Plant Microbe Interactions and Cluster of Excellence in Plant Sciences Max Planck Institute for Plant Breeding Research 50829 Cologne Germany

Facultad de Veterinaria y Ciencias Experimentales Universidad Catόlica de Valencia 46001 Valencia Spain

Fundaciόn Instituto Leloir Instituto de Investigaciones Bioquίmicas de Buenos Aires Consejo Nacional de Investigaciones Cientίficas y Técnicas 1405 Buenos Aires Argentina

Institute of Synthetic Biology and Cluster of Excellence in Plant Sciences University of Düsseldorf 40225 Düsseldorf Germany

Instituto de Biologίa Molecular y Celular de Plantas Consejo Superior de Investigaciones Cientίficas Universidad Politécnica de Valencia 46022 Valencia Spain

Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura Facultad de Agronomίa Universidad de Buenos Aires Consejo Nacional de Investigaciones Cientίficas y Técnicas 1417 Buenos Aires Argentina

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