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Floral induction in tissue culture: a system for the analysis of LEAFY‐dependent gene regulation
Author(s) -
Wagner Doris,
Wellmer Frank,
Dilks Kieran,
William Dilusha,
Smith Michael R.,
Kumar Prakash P.,
Riechmann José Luis,
Greenland Andrew J.,
Meyerowitz Elliot M.
Publication year - 2004
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2004.02127.x
Subject(s) - leafy , biology , gene expression , gene , ectopic expression , callus , microbiology and biotechnology , complementary dna , botany , explant culture , reporter gene , arabidopsis , genetics , mutant , in vitro
Summary 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.