(E)-beta-Farnesene synthase genes affect aphid (Myzus persicae) infestation in tobacco (Nicotiana tabacum)

Aphids are major agricultural pests which cause significant yield losses of the crop plants each year. (E)-beta-farnesene (E beta F) is the alarm pheromone involved in the chemical communication between aphids and particularly in the avoidance of predation. In the present study, two E beta F synthase genes were isolated from sweet wormwood and designated as Aa beta FS1 and Aa beta FS2, respectively. Overexpression of Aa beta FS1 or Aa beta FS2 in tobacco plants resulted in the emission of E beta F ranging from 1.55 to 4.65 ng/day/g fresh tissues. Tritrophic interactions involving the peach aphids (Myzus persicae), predatory lacewings (Chrysopa septempunctata) demonstrated that the transgenic tobacco expressing Aa beta FS1 and Aa beta FS2 could repel peach aphids, but not as strongly as expected. However, Aa beta FS1 and Aa beta FS2 lines exhibited strong and statistically significant attraction to lacewings. Further experiments combining aphids and lacewing larvae in an octagon arrangement showed transgenic tobacco plants could repel aphids and attract lacewing larvae, thus minimizing aphid infestation. Therefore, we demonstrated a potentially valuable strategy of using E beta F synthase genes from sweet wormwood for aphid control in tobacco or other economic important crops in an environmentally benign way.