Resistance against beet armyworms and cotton aphids in caffeine-producing transgenic chrysanthemum

Abstract

Transgenic chrysanthemum plants were constructed to simultaneously express three N-methyltransferases involved in caffeine biosynthetic pathways. Resulting plants produced caffeine at approximately 3 μg g⁻¹ fresh tissue, and were tested for herbivore repellence. When starved second-instar caterpillars of beet armyworms (Spodoptera exigu) were allowed to feed, they ate up to 4.4 mm² of leaf discs from the wild type plants, while less than 1.5 mm² of those from the transgenic plants. When third-instars of cotton aphid (Aphis gossypii) were subjected to a choice-test, 27 gathered on wild type leaves, and 6 on transgenic leaves. These results indicate that caffeine-producing chrysanthemum is resistant against herbivores, lepidoptera caterpillars and aphids, both being one of the most serious pests in agriculture. We propose that the method can be practically applied to a variety of important plant species to confer resistance against biotic stresses.