title: Floral induction in tissue culture: a system for the analysis of LEAFY-dependent gene regulation.
abstract: We have developed a versatile floral induction system that is based on ectopic overexpression of the transcription factor LEAFY (LFY) in callus. During shoot regeneration, flowers or floral organs are formed directly from root explants without prior formation of rosette leaves. Morphological and reporter gene analyses show that leaf-like structures are converted to floral organs in response to LFY activity. Thus, increased levels of LFY activity are sufficient to bypass normal vegetative development and to direct formation of flowers in tissue culture. We found that about half of the cultured cells respond to inducible LFY activity with a rapid upregulation of the known direct target gene of LFY, APETALA1 (AP1). This dramatic increase in the number of LFY-responsive cells compared to whole plants suggested that the tissue culture system could greatly facilitate the analysis of LFY-dependent gene regulation by genomic approaches. To test this, we monitored the gene expression changes that occur in tissue culture after activation of LFY using a flower-specific cDNA microarray. Induction of known LFY target genes was readily detected in these experiments. In addition, several other genes were identified that had not been implicated in signaling downstream of LFY before. Thus, the floral induction system is suitable for the detection of low abundance transcripts whose expression is controlled in an LFY-dependent manner.
authors.affiliation: Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA.
authors.forename: Doris
authors.initials: D
authors.lastname: Wagner
authors.forename: Frank
authors.initials: F
authors.lastname: Wellmer
authors.forename: Kieran
authors.initials: K
authors.lastname: Dilks
authors.forename: Dilusha
authors.initials: D
authors.lastname: William
authors.forename: Michael R
authors.initials: MR
authors.lastname: Smith
authors.forename: Prakash P
authors.initials: PP
authors.lastname: Kumar
authors.forename: José Luis
authors.initials: JL
authors.lastname: Riechmann
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Greenland
authors.forename: Elliot M
authors.initials: EM
authors.lastname: Meyerowitz
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D046508:Culture Techniques / Q000379:methods*; D035264:Flowers / Q000254:growth & development*; D018506:Gene Expression Regulation, Plant; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D026161:MADS Domain Proteins; D020411:Oligonucleotide Array Sequence Analysis; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018520:Plant Shoots / Q000254:growth & development; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: C091535:AP1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D018398:Homeodomain Proteins; C074747:LFY protein, Arabidopsis; D026161:MADS Domain Proteins; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors