title: Regulation of APETALA3 floral homeotic gene expression by meristem identity genes.
abstract: The Arabidopsis APETALA3 (AP3) floral homeotic gene is required for specifying petal and stamen identities, and is expressed in a spatially limited domain of cells in the floral meristem that will give rise to these organs. Here we show that the floral meristem identity genes LEAFY (LFY) and APETALA1 (AP1) are required for the activation of AP3. The LFY transcription factor binds to a sequence, with dyad symmetry, that lies within a region of the AP3 promoter required for early expression of AP3. Mutation of this region abolishes LFY binding in vitro and in yeast one hybrid assays, but has no obvious effect on AP3 expression in planta. Experiments using a steroid-inducible form of LFY show that, in contrast to its direct transcriptional activation of other floral homeotic genes, LFY acts in both a direct and an indirect manner to regulate AP3 expression. This LFY-induced expression of AP3 depends in part on the function of the APETALA1 (AP1) floral homeotic gene, since mutations in AP1 reduce LFY-dependent induction of AP3 expression. LFY therefore appears to act through several pathways, one of which is dependent on AP1 activity, to regulate AP3 expression.
authors.affiliation: Department of Molecular, Cellular and Developmental Biology, Yale University, P.O. Box 208104, New Haven, CT 06520, USA.
authors.forename: Rebecca S
authors.initials: RS
authors.lastname: Lamb
authors.forename: Theresa A
authors.initials: TA
authors.lastname: Hill
authors.forename: Queenie K-G
authors.initials: QK
authors.lastname: Tan
authors.forename: Vivian F
authors.initials: VF
authors.lastname: Irish
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics*; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D005801:Genes, Homeobox; D017343:Genes, Plant; D018398:Homeodomain Proteins / Q000235:genetics; D026161:MADS Domain Proteins / Q000235:genetics*; D018519:Meristem / Q000235:genetics / Q000254:growth & development; D008957:Models, Genetic; D009154:Mutation; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic; D014157:Transcription Factors; D014158:Transcription, Genetic
chemical_list: C091535:AP1 protein, Arabidopsis; C101342:APETALA 3 protein, Arabidopsis; D029681:Arabidopsis Proteins; D018744:DNA, Plant; D018398:Homeodomain Proteins; C074747:LFY protein, Arabidopsis; D026161:MADS Domain Proteins; D010940:Plant Proteins; D014157:Transcription Factors