Analysis of Amino Acid and Protein Insecticides for Transgenic Crops. (Botany & Plant Ecology).
White flies (Bemesia tabaci) are a major source of crop damage in the southwestern United States. To counter this problem, protease inhibitors as well as tryptamine have been shown to have considerable insecticidal properties. Nicotiana tabacum (tobacco) were developed expressing protease inhibitors from Manduca sexta or the enzyme tryptophan decarboxylase from Catharanthus roseus (periwinkle). Tryptophan decarboxylase produces tryptamine from tryptophan. White fly fecundity was subsequently reduced when insects were introduced to transgenic plants expressing these insecticides. Protease inhibitors may restrict insect development by inhibiting the activity of endopeptidases elastase and trypsin. Our findings have shown that environmental stress (measured by proline accumulation) also lowers the effectiveness of PIs as insecticides. The mechanism of tryptamine toxicity is complex. Our working hypothesis is that tryptamine inhibits succinate dehydrogenase (SDH), a Krebs cycle enzyme that converts succinate to fumerate ultimately increasing ATP levels. Following tryptamine treatment, Drosophila SDH activity decreased significantly. Our goal is to quantify trypramine levels in leaves of transgenic plants and determine tryptamine's mechanism of toxicity.
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|Article Type:||Brief Article|
|Date:||Mar 22, 2002|
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