Genome-wide identification, phylogenetic analysis, and expression profiles of ATP-binding cassette transporter genes in the oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae)

Abstract

The ATP-binding cassette (ABC) is the largest transporter gene family and the genes play key roles in xenobiotic resistance, metabolism, and development of all phyla. However, the specific functions of ABC gene families in insects is unclear. We report a genome-wide identification, phylogenetic, and transcriptional analysis of the ABC genes in the oriental fruit fly, Bactrocera dorsalis (Hendel). We identified a total of 47 ABC genes (BdABCs) from the transcriptomic and genomic databases of B. dorsalis and classified these genes into eight subfamilies (A-H), including 7 ABCAs, 7 ABCBs, 9 ABCCs, 2 ABCDs, 1 ABCE, 3 ABCFs, 15 ABCGs, and 3 ABCHs. Comparative phylogenetic analysis of the ABCs suggests an orthologous relationship between B. dorsalis and other insect species in which these genes have been related to pesticide resistance and essential biological processes. Comparison of transcriptome and relative expression patterns of BdABCs indicated diverse multifunctions within different B. dorsalis tissues. The expression of 4, 10, and 14 BdABCs from 18 BdABCs was significantly upregulated after exposure to LD₅₀s of malathion, avermectin, and beta-cypermethrin, respectively. The maximum expression level of most BdABCs (including BdABCFs, BdABCGs, and BdABCHs) occurred at 48h post exposures, whereas BdABCEs peaked at 24h after treatment. Furthermore, RNA interference-mediated suppression of BdABCB7 resulted in increased toxicity of malathion against B. dorsalis. These data suggest that ABC transporter genes might play key roles in xenobiotic metabolism and biosynthesis in B. dorsalis.

Keywords: ABC transporters; Bactrocera dorsalis; Insecticide exposures; RNA interference; mRNA expression.