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Tryptophan Decarboxylase, Tryptamine, and Reproduction of the Whitefly
J. C. Thomas1, D. G. Adams, C. L. Nessler
1Department of Biochemistry (J.C.T., D.G.A., H.J.B.) and Department of Plant Sciences (J.K.B., H.J.B.), University of Arizona, Tucson, Arizona 85721.
Plant Physiology
|October 1, 1995
Summary
Transgenic tobacco plants expressing the tryptophan decarboxylase (TDC) gene produced tryptamine, significantly reducing sweetpotato whitefly reproduction by up to 97%. This offers a novel single-gene strategy for plant protection against insect pests.
Area of Science:
- Plant biotechnology
- Entomology
- Biochemistry
Background:
- Tryptophan decarboxylase (TDC) is an enzyme found in Catharanthus roseus.
- TDC catalyzes the conversion of tryptophan to tryptamine, an indole alkaloid.
- Insect pests pose a significant threat to crop yields worldwide.
Purpose of the Study:
- To investigate the potential of expressing the TDC gene in transgenic tobacco plants.
- To assess the impact of TDC expression and subsequent tryptamine accumulation on Bemisia tabaci (sweetpotato whitefly) reproduction.
- To explore a single-gene-based plant protection strategy against insect pests.
Main Methods:
- Gene expression: The TDC gene from Catharanthus roseus was expressed in tobacco plants.
- Biochemical analysis: Accumulation of the TDC enzyme and tryptamine was measured in transgenic plants.
- Insect bioassay: The reproductive success of Bemisia tabaci on transgenic and control plants was evaluated.
Main Results:
- Transgenic tobacco plants successfully expressed the 55-kD TDC enzyme.
- Significant accumulation of tryptamine was observed in transgenic plants.
- Bemisia tabaci reproduction on transgenic plants decreased by up to 97% compared to control plants.
Conclusions:
- Expression of the tryptophan decarboxylase gene in tobacco confers resistance to sweetpotato whiteflies.
- Tryptamine production, or related compounds, may act as a deterrent to whitefly reproduction.
- This study demonstrates a promising single-gene approach for developing insect-resistant crops.