A chimaeric tryptophan decarboxylase gene as a novel selectable marker in plant cells

Plant Mol Biol. 1993 Aug;22(5):907-12. doi: 10.1007/BF00027376.


A novel selection system for plant genetic transformation was developed based on the enzyme tryptophan decarboxylase (TDC; EC from Catharanthus roseus. This enzyme converts the toxic tryptophan analogue 4-methyl tryptophan (4-mT) into the non-toxic compound 4-methyl tryptamine. Expression of tdc in transgenic plants that have no endogenous TDC-activity allows selection on 4-mT. A vector was constructed containing a tdc cDNA clone under control of the constitutively expressed cauliflower mosaic virus 35S promoter. This vector was used in Agrobacterium-mediated tobacco leaf disc transformation experiments. The optimal concentration for selection with 4-mT was found to be 0.1 mM. The transformed nature of shoots obtained after tdc gene transfer and subsequent selection on 0.1 mM 4-mT was confirmed by northern blot analysis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aromatic-L-Amino-Acid Decarboxylases / genetics*
  • Aromatic-L-Amino-Acid Decarboxylases / metabolism
  • Cloning, Molecular
  • Genetic Markers*
  • Kanamycin / pharmacology
  • Plants, Genetically Modified
  • Plants, Toxic*
  • Restriction Mapping
  • Tobacco / cytology
  • Tobacco / enzymology
  • Tobacco / genetics*
  • Transformation, Genetic
  • Tryptophan / analogs & derivatives
  • Tryptophan / pharmacology


  • Genetic Markers
  • 4-methyltryptophan
  • Kanamycin
  • Tryptophan
  • Aromatic-L-Amino-Acid Decarboxylases