Functional characterization of heterologously expressed codling moth olfactory receptors

The Codling Moth (Cydia pomonella L.), is one of the most notorious pest species threatening apple, pear, walnuts and other fruit orchards worldwide. Olfaction plays a dominate role in the ‘host’-selection behavior of the Codling Moth. Earlier, based on antennal transcriptome analysis we identified a number of critical elements of the moth olfactory system, including Olfactory Receptors (ORs) the co-receptor (CpomORCO) and the potential Pheromone Receptors CpomOR1, CpomOR3, CpomOR4, CpomOR5, CpomOR6 (Bengtsson et al 2012). To date we have described CpomOR3 using heterologous expression in Drosophila T1 trichoid and ab3A basiconic sensilla (Bengtsson et al 2014). We now extensively characterize recombinant Codling Moth ORs transiently expressed in HEK cells. Using calcium imaging and whole-cell and outside-out patch clamp recordings, we demonstrate that both the homomeric CpomORco channel forming subunit and heteromeric CpomOR complexes can be activated by the ORCO agonists VUAA1 and VUAA3. Different OR complexes show different sensitivity to the agonists and different activation/inactivation kinetics. Both the homo- and heteromeric OR complexes were also susceptible to inhibition by amiloride derivatives when activated by agonists. Functional expression of CpomORs therefore represents a valuable tool that can be utilized to further investigate mechanisms of insect OR function and develop novel means to intervene and control the pest’s behavior. A larger scale physiological and molecular analysis is under way to identify and characterize unique physiological properties of the receptors.