Arabidopsis AtMYC2 (bHLH) and AtMYB2 (MYB) Function as Transcriptional Activators in Abscisic Acid Signaling

DOI Web Site PubMed 28 Citations Open Access
  • Hiroshi Abe
    Biological Resources Division, Japan International Research Center for Agricultural Sciences, 1-1 Ohwashi, Tsukuba, Ibaraki 305-8686, Japan
  • Takeshi Urao
    Biological Resources Division, Japan International Research Center for Agricultural Sciences, 1-1 Ohwashi, Tsukuba, Ibaraki 305-8686, Japan
  • Takuya Ito
    Laboratory of Plant Molecular Biology, RIKEN Tsukuba Institute, 3-1-1 Koyadai, Tsukuba, Ibaraki 305-0074, Japan
  • Motoaki Seki
    Laboratory of Plant Molecular Biology, RIKEN Tsukuba Institute, 3-1-1 Koyadai, Tsukuba, Ibaraki 305-0074, Japan
  • Kazuo Shinozaki
    Laboratory of Plant Molecular Biology, RIKEN Tsukuba Institute, 3-1-1 Koyadai, Tsukuba, Ibaraki 305-0074, Japan
  • Kazuko Yamaguchi-Shinozaki
    Biological Resources Division, Japan International Research Center for Agricultural Sciences, 1-1 Ohwashi, Tsukuba, Ibaraki 305-8686, Japan

Description

In Arabidopsis, the induction of a dehydration-responsive gene, rd22, is mediated by abscisic acid (ABA). We reported previously that MYC and MYB recognition sites in the rd22 promoter region function as cis-acting elements in the drought- and ABA-induced gene expression of rd22. bHLH- and MYB-related transcription factors, rd22BP1 (renamed AtMYC2) and AtMYB2, interact specifically with the MYC and MYB recognition sites, respectively, in vitro and activate the transcription of the beta-glucuronidase reporter gene driven by the MYC and MYB recognition sites in Arabidopsis leaf protoplasts. Here, we show that transgenic plants overexpressing AtMYC2 and/or AtMYB2 cDNAs have higher sensitivity to ABA. The ABA-induced gene expression of rd22 and AtADH1 was enhanced in these transgenic plants. Microarray analysis of the transgenic plants overexpressing both AtMYC2 and AtMYB2 cDNAs revealed that several ABA-inducible genes also are upregulated in the transgenic plants. By contrast, a Ds insertion mutant of the AtMYC2 gene was less sensitive to ABA and showed significantly decreased ABA-induced gene expression of rd22 and AtADH1. These results indicate that both AtMYC2 and AtMYB2 proteins function as transcriptional activators in ABA-inducible gene expression under drought stress in plants.

Journal

  • The Plant Cell

    The Plant Cell 15 (1), 63-78, 2002-12-19

    Oxford University Press (OUP)

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