title: GIGANTEA enables drought escape response via abscisic acid-dependent activation of the florigens and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS.
abstract: Modulation of the transition to flowering plays an important role in the adaptation to drought. The drought-escape (DE) response allows plants to adaptively shorten their life cycle to make seeds before severe stress leads to death. However, the molecular basis of the DE response is unknown. A screen of different Arabidopsis (Arabidopsis thaliana) flowering time mutants under DE-triggering conditions revealed the central role of the flower-promoting gene GIGANTEA (GI) and the florigen genes FLOWERING LOCUS T (FT) and TWIN SISTER OF FT (TSF) in the DE response. Further screens showed that the phytohormone abscisic acid is required for the DE response, positively regulating flowering under long-day conditions. Drought stress promotes the transcriptional up-regulation of the florigens in an abscisic acid- and photoperiod-dependent manner, so that early flowering only occurs under long days. Along with the florigens, the floral integrator SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 is also up-regulated in a similar fashion and contributes to the activation of TSF. The DE response was recovered under short days in the absence of the floral repressor SHORT VEGETATIVE PHASE or in GI-overexpressing plants. Our data reveal a key role for GI in connecting photoperiodic cues and environmental stress independently from the central FT/TSF activator CONSTANS. This mechanism explains how environmental cues may act upon the florigen genes in a photoperiodically controlled manner, thus enabling plastic flowering responses.
authors.affiliation: Department of Life Sciences, University of Milan, 20133 Milan, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Riboni
authors.forename: Massimo
authors.initials: M
authors.lastname: Galbiati
authors.forename: Chiara
authors.initials: C
authors.lastname: Tonelli
authors.forename: Lucio
authors.initials: L
authors.lastname: Conti
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D017360:Arabidopsis / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D055864:Droughts; D060405:Florigen / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D026161:MADS Domain Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D049488:Phosphatidylethanolamine Binding Protein / Q000235:genetics / Q000378:metabolism; D017440:Photoperiod; D030821:Plants, Genetically Modified; D013312:Stress, Physiological; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: C419046:AGL20 protein, Arabidopsis; D029681:Arabidopsis Proteins; C092776:CONSTANS protein, Arabidopsis; D004268:DNA-Binding Proteins; C418905:FT protein, Arabidopsis; D060405:Florigen; C121183:GI protein, Arabidopsis; D026161:MADS Domain Proteins; D049488:Phosphatidylethanolamine Binding Protein; C500577:TSF protein, Arabidopsis; D014157:Transcription Factors; D000040:Abscisic Acid