Coping with enemy defenses: gene expression analysis of a specialist mirid feeding on defenseless tobacco plants

Plant-insect interactions have driven the evolution of both organisms, in a sort of evolutionary arm race where plants have evolved different chemical defenses to escape from insect pressure, and in turn, insects evolved detoxification mechanisms to overcome plant toxic metabolites. Specialist insects, compared to generalists, often rely on well-developed specific enzymatic systems that allow them to metabolize otherwise toxic plant chemicals. Nicotiana attenuata (Torr. ex S.Watson), the coyote tobacco that extensively grows in the Utah desert, is a model plants whose sophisticated array of defenses has been extensively studied. In the present work, preliminary results of the molecular interactions between N. attenuata and one of its specialists, the mirid Tupiocoris notatus (Distant), are presented. We used RNAseq to compare T. notatus gene expression when fed on wild-type plants and plants silenced in jasmonic acid (JA)-mediated defenses. Insects that fed on JA-silenced plants showed a greater number of down-regulated transcripts than up-regulated transcripts. Among differently regulated genes we identified cytochromes P450 as well as other enzymes involved in detoxification and stress-response. Our results shed light on the molecular mechanisms of adaption that T. notatus evolved to cope with N. attenuata.