title: Integrating long-day flowering signals: a LEAFY binding site is essential for proper photoperiodic activation of APETALA1.
abstract: The transition to flowering in Arabidopsis is characterized by the sharp and localized upregulation of APETALA1 (AP1) transcription in the newly formed floral primordia. Both the flower meristem-identity gene LEAFY (LFY) and the photoperiod pathway involving the FLOWERING LOCUS T (FT) and FD genes contribute to this upregulation. These pathways have been proposed to act independently but their respective contributions and mode of interaction have remained elusive. To address these questions, we studied the AP1 regulatory region. Combining in vitro and in vivo approaches, we identified which of the three putative LFY binding sites present in the AP1 promoter is essential for its activation by LFY. Interestingly, we found that this site is also important for the correct photoperiodic-dependent upregulation of AP1. In contrast, a previously proposed putative FD-binding site appears dispensable and unable to bind FD and we found no evidence for FD binding to other sites in the AP1 promoter, suggesting that the FT/FD-dependent activation of AP1 might be indirect. Altogether, our data give new insight into the interaction between the FT and LFY pathways in the upregulation of AP1 transcription under long-day conditions.
authors.affiliation: CEA, iRTSV, Laboratoire Physiologie Cellulaire et Végétale, F-38054 Grenoble, France.
authors.forename: Reyes
authors.initials: R
authors.lastname: Benlloch
authors.forename: Min Chul
authors.initials: MC
authors.lastname: Kim
authors.forename: Camille
authors.initials: C
authors.lastname: Sayou
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Thévenon
authors.forename: Francois
authors.initials: F
authors.lastname: Parcy
authors.forename: Ove
authors.initials: O
authors.lastname: Nilsson
mesh_terms: D017360:Arabidopsis / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D035264:Flowers / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D026161:MADS Domain Proteins / Q000235:genetics / Q000378:metabolism*; D017440:Photoperiod; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: C091535:AP1 protein, Arabidopsis; D029681:Arabidopsis Proteins; C074747:LFY protein, Arabidopsis; D026161:MADS Domain Proteins; D014157:Transcription Factors