Abstract: As one main Lepidopteran pest in tea garden, the larvae of tea geometrid damages mainly the tea leaves, which severely reduce the yield of tea products. The olfactory system of tea geometrid plays a very important role in terms of seeking host and food. Therefore, a general odorant binding protein—EoblGOBP2, existing in the olfactory system of tea geometrid, the function binding with tea plant volatiles was studied in vitro here. Based on the cloned EoblGOBP2 gene by RT-PCR, the recombinant protein EoblGOBP2 was successfully expressed in an optimized prokaryotic prokaryotic expression system, then the binding characteristics of the purified EoblGOBP2 with 1-NPN was measured by fluorescence spectrometry. Scatchard plot analysis indicated that the dissociation constant between EoblGOBP2 and 1-NPN was 2.310 μmol·L^-1. In the competitive binding assays, to the seven candidate ligands, all of the relative fluorescence intensity of 1-NPN decreased more than 50%, which suggested that all of the tested ligands have strong binding capability with EoblGOBP2. The compound of dibutyl phthalate showed the maximum binding capability with EoblGOBP2, and their dissociation constant was 4.353 μmol·L^-1. As all of the candidate chemical ligands belong to the tea volatiles secondary metabolites, indicating that EoblGOBP2 plays an important role in the odor recognition process of olfactory identification in the olfactory system of tea geometrid.

Key words: Ectropis oblique, general odorant binding protein, prokaryotic expression, purification, tea plant volatiles, binding characteristics