RNA interference of Manduca sexta using chloroplast-encoded long dsRNA.

RNA interference is a promising tool for the development of pest management strategies which target specific species of insect. However, orally administered double-stranded RNA is inefficient at knocking down gene expression in species within the order Lepidoptera, a clade which includes some of the most common agricultural pests. Transplastomic plants expressing dsRNA within their chloroplasts are a promising method of delivering dsRNA to the pest, as bio-encapsulation within the plastid protects the dsRNA from nucleases in the feeding insect’s midgut and localization within the chloroplast prevents processing by the plant’s innate RNAi pathway. We transformed the chloroplast genome of tobacco Nicotiana tabacum to express a 2222 base pair dsRNA with sequence complementarity to the vacuolar ATPase subunit A gene of tobacco hornworm Manduca sexta. Bioassays using M. sexta larvae are being performed to determine if knockdown of vATPase A gene expression or lethality occur as a result of feeding on the transformed plants. Plants expressing insecticidal chloroplast dsRNA could be utilized as trap plants to be grown alongside agriculturally important crops in a greenhouse or field setting to lure and kill pest insects.