Conserved MYC transcription factors play a key role in jasmonate signaling both in tomato and <i>Arabidopsis</i>

抄録

<jats:p>Jasmonates (JA) are important regulators of plant defense responses that activate expression of many wound-induced genes including the tomato proteinase inhibitor II (<jats:italic>pin2</jats:italic>) and leucine aminopeptidase (<jats:italic>LAP</jats:italic>) genes. Elements required for JA induction of the <jats:italic>LAP</jats:italic> gene are all present in the -317 to -78 proximal promoter region. Using yeast one-hybrid screening, we have identified the bHLH-leu zipper JAMYC2 and JAMYC10 proteins, specifically recognizing a T/G-box AACGTG motif in this promoter fragment. Mutation of the G-box element decreases JA-responsive <jats:italic>LAP</jats:italic> promoter expression. Expression of <jats:italic>JAMYC2</jats:italic> and <jats:italic>JAMYC10</jats:italic> is induced by JA, with a kinetics that precedes that of the <jats:italic>LAP</jats:italic> or <jats:italic>pin2</jats:italic> transcripts. JAMYC overexpression enhanced JA-induced expression of these defense genes in potato, but did not result in constitutive transcript accumulation. Using footprinting assays, an additional protected element was identified, located directly adjacent to the T/G-box motif. Mutation of this element abolishes JA response, showing that recognition of this duplicated element is also required for gene expression. Knockout mutants in the <jats:italic>AtMYC2</jats:italic> homolog gene of <jats:italic>Arabidopsis</jats:italic> are insensitive to JA and exhibit a decreased activation of the JA-responsive genes <jats:italic>AtVSP</jats:italic> and <jats:italic>JR1</jats:italic>. Activation of the <jats:italic>PDF1.2</jats:italic> and <jats:italic>b-CHI</jats:italic>, ethylene/JA-responsive genes, is, however, increased in these mutants. These results show that the JAMYC/AtMYC2 transcription factors function as members of a MYC-based regulatory system conserved in dicotyledonous plants with a key role in JA-induced defense gene activation.</jats:p>

収録刊行物

  • Genes & Development

    Genes & Development 18 (13), 1577-1591, 2004-07-01

    Cold Spring Harbor Laboratory

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