Abstract: 【Aim】 The objective of this study is to clone an odorant receptor gene from the diamondback moth, Plutella xylostella, characterize its expression profiles in different tissues and investigate its function. Our study provides a theoretical basis for understanding the mechanisms of host plant recognition of the diamondback moth. 【Methods】 The full-length cDNA sequence of PxylOR9 gene was obtained and cloned based on the transcriptome analysis of adult P. xylostella antennae. The relative expression levels of this gene in different tissues of both adult males and females were detected using semi-quantitative RTPCR. Two-electrode voltage clamp electrophysiological recording was used to test the response of Xenopus oocytes injected with PxylOR9 to 59 plant volatiles in vitro. 【Results】 Based on transcriptome sequencing and analysis in the preliminary study, several sequences of odorant receptors were predicted in P. xylostella. The full length cDNA of one of these genes, PxylOR9 (GenBank accession number: KP757898), was cloned in this study. Sequence analysis revealed that PxylOR9 has six transmembrane domains with an intracellular N-terminus, which is the typical structure of insect odorant receptors. Phylogenetic analysis showed that PxylOR9 is obviously different from sex pheromone receptors of several lepidopteran insects, but cluster together with their other general odorant receptors. The semi-quantitative RT-PCR results showed that the expression level of PxylOR9 was much higher in the antennae of both males and females than in other tissues. Voltage clamp electrophysiological recording indicated that PxylOR9 could only respond to the stimulation with β-ionone among the tested plant volatiles. 【Conclusion】 PxylOR9 of P. xylostella belongs to the general odorant receptor with a typical characteristic. PxylOR9 is highly expressed in adult antennae of P. xylostella. PxylOR9 can be activated by plant volatile β-ionone, implying that PxylOR9 may be involved in the recognition of P. xylostella to plants.

Key words: Plutella xylostella, general odorant receptor, semi-quantitative RT-PCR, two-electrode voltage clamp, β-ionone