Phenotypic, biochemical and molecular analysis of punctual substitutions in CONSTITUTIVE PHOTOMORPHOGENIC 1 in Arabidopsis thalianaplants

CRISTIAN M. ESCUDERO; JAVIER F. BOTTO

Foz do Iguazu

Congreso; 11th international Congress of Plant Molecular Biology; 2015

CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1) is a highly conserved protein with E3 ubiquitin ligase activity that acts as a potent negative regulator of photomorphogenesis. COP1 protein comprises three recognizable domains (RING finger, coiled-coil and WD40) involved in protein-protein interactions. The aim of this study is to investigate the COP1 signaling mechanisms evaluating the functional importance of the WD40 domain in different developmental responses. By physiological characterization of Arabidopsis transgenic plants that have independent amino acid substitutions in the WD40 domain, we found that some aminoacid changes can promote and other cancel the shade avoidance hypocotyl growth. In these substitution lines, we observed that the expression of transcription factors and auxin genes are deregulated. Interestingly, the shade avoidance response was recovered in the non-responsive transgenic line when seedlings were grown in a medium with GA4, but not with auxin, suggesting that the protein-protein interaction in this region could affect directly or indirectly the gibberellin signaling that promote hypocotyl elongation. Furthermore, specific aminoacid substitutions in the WD40 domain of COP1 accelerate flowering time because CO (CONSTANS) and COP1 interaction is impeded, and consequently FT (Flowering Locus T) expression is high. Our results suggest that the WD40 domain of COP1 is relevant for specific protein-protein interactions in developmental responses along the life cycle of the plant.