Plasmid engineering of aphid alarm pheromone in tobacco seedlings affects the preference of aphids

Plants producing sufficient amount of aphid alarm pheromone by expressing (E)-beta-Farnesene (E beta F) synthase gene may contribute to plant protection by reducing aphid populations. However, terpene biosynthesis varies among plant species and developmental stages. In the present study, volatile headspace analysis of tobacco seedlings with Ma beta FS1 (an E beta F synthase from the Asian peppermint Mentha asiatica) failed to generate E beta F. We further targeted Ma beta FS1 to the tobacco plastid, using a chloroplast targeting sequence, either with or without the AtFPS1 gene for the biosynthesis of the precursor farnesyl diphosphate. When both Ma beta FS1 and AtFPS1 genes were targeted to the chloroplast, low levels of E beta F were detected in stably transformed tobacco seedlings; resulting in specific repellence of the green peach aphid, Myzus persicae. These data indicate that redirecting the E beta F biosynthetic pathway from its natural cytosolic location to the chloroplast is a valid strategy. This redirecting strategy may be very useful for other crop plants that do not naturally produce E beta F or other repellent volatiles.