Suppression of a P450 hydroxylase gene in plant trichome glands enhances natural-product-based aphid resistance

Trichome glands on the surface of many higher plants produce and secrete exudates affecting insects, microbes, and herbivores. Metabolic engineering of gland exudation has potential for improving pest/disease resistance, and for facilitating molecular farming. We identified a cytochrome P450 hydroxylase gene specific to the trichome gland and used both antisense and sense co-suppression strategies to investigate its function. P P450-suppressed transgenic tobacco plants showed a greater than or equal to 41% decrease in the predominant exudate component, cembratriene-diol (CBT-diol), and a greater than or equal to 19-fold increase in its precursor, cembratriene-ol (CBT-ol). Thus, the level of CBT-ol was raised from 0.2 to greater than or equal to4.3% of leaf dry weight. Exudate from antisense-expressing plants had higher aphidicidal activity, and transgenic plants with exudate containing high concentrations of CBT-ol showed greatly diminished aphid colonization responses. Our results demonstrate the feasibility of significantly modifying the natural-product chemical composition and aphid-interactive properties of gland exudates using metabolic engineering. The results also have implications for molecular farming.