Genome-wide identification of ATP-binding cassette transporters and expression profiles in the Asian citrus psyllid, Diaphorina citri, exposed to imidacloprid.

ATP-binding cassette (ABC) transporters belong to a large protein superfamily found in both prokaryotic and eukaryotic organisms. In arthropods, ABC transporters are involved in defense and resistance to insecticides. The Asian citrus psyllid (ACP), Diaphorina citri, is a major vector of the Huanglongbing pathogen (Candidatus Liberibacter asiaticus) worldwide. In this study, the ABC transporter genes were identified based on the transcriptome and genome database of D. citri. A total of 44 DcitABC transporters were identified and grouped into 8 subfamilies (ABCA-ABCH), including 4 DcitABCAs, 4 Bs, 5 Cs, 2 Ds, 1 E, 3 Fs, 15 Gs and 10 Hs, respectively. Phylogenetic analysis of ABC transporters revealed a close relationship between D. citri and Laodelphax striatellus. qPCR analyses showed that several DcitABC transporters were highly expressed in fat body, midgut and the hindgut with Malpighian tubules. In particular, DcitABCG11 and DcitABCG14 were most highly expressed in the hindgut. The transcript abundance of 11 DcitABC genes was significantly upregulated upon exposure to an LC50 concentration of imidacloprid. The expressions of three cytochrome P450 genes and one glutathione S-transferase gene were also significantly elevated. This suggested that DcitABC genes, together with metabolic enzyme genes, are associated with imidacloprid detoxification.