Full Paper

Plant Molecular Biology

, Volume 17, Issue 3, pp 567-579

First online:

Auxin-induced expression of the soybean GH3 promoter in transgenic tobacco plants

  • Gretchen HagenAffiliated withDepartment of Biochemistry, University of Missouri
  • , Gary MartinAffiliated withDepartment of Biochemistry, University of Missouri
  • , Yi LiAffiliated withDepartment of Biochemistry, University of Missouri
  • , Tom J. GuilfoyleAffiliated withDepartment of Biochemistry, University of Missouri

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The gene encoding the auxin-responsive GH3 mRNA (G. Hagen, A. Kleinschmidt, TJ. Guilfoyle, Planta 162: 147–153 (1984)) from soybean was cloned, and its sequence and transcription initiation site were determined. The promoter of the GH3 gene has been fused to the open reading frame of theEscherichia coli uidA gene which encodes β-glucuronidase (GUS). This fusion gene was introduced into tobacco viaAgrobacterium tumefaciens-mediated transformation, and the expression of the gene was examined by fluorometric assay and histochemical staining of young R1 tobacco seedlings and mature plants. In transgenic tobacco plants that have not been exposed to exogenous auxin, expression of the fusion gene is largely restricted to roots of young green plants and developing floral organs, including ovules, developing seeds, and pollen, of mature plants. Application of exogenous auxin to tobacco seedlings or plant organs results in a greater than 50-fold increase in expression of GUS. Auxin-induced GUS expression is greates in vascular tissue, but not restricted to this tissue. The auxin-deduced GUS expression was characterized for kinetics, auxin specificity and dose response.

Key words

auxin GH3 gene transgenic tobacco auxin-regulated gene expression