Submitted to: Natural Toxins
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 4, 1995
Publication Date: N/A
Interpretive Summary: Identifying mechanisms by which plants resist insects is important in solving insect pest problems on crop plants. We found that the toxicity of several plant defensive compounds to a leafhopper was significantly increased by plant enzymes that can add oxygen to these compounds. This enzyme activity may be followed readily during plant breeding or introduced by genetic engineering to promote plant resistance to insects.
Technical Abstract: Oxidation products generated by peroxidases or tyrosinases were tested in 10% sucrose solutions for effects on the corn leafhopper Dalbulus maidis. Some reduction in feeding was noted with hydrogen peroxide (a co-factor for peroxidase). Significant reduction in feeding was noted with chlorogenic acid, ferulic acid, p-coumaric acid, and 6- methoxybenzoxazolinone (MBOA), but not rutin at 1000 ppm in solution. Oxidation products of these compounds all caused significantly less feeding by the leafhoppers compared to the original compound. Oxidation products generated by peroxidase from ferulic acid and 6-methoxybenzoxazolinone caused significant mortality to the leafhoppers within 5 days. Thus, provided conditions are such that oxidizing enzymes and allelochemicals can interact due to damage by insects, resistance may be significantly enhanced by the oxidized products as opposed to the effects of the allelochemicals alone.