Multiple ATP-binding cassette transporters genes are involved in thiamethoxam resistance in Aphis gossypii glover

ATP-binding cassette (ABC) transporters represent the largest known group of efflux pumps, utilizing ATP to translocate a broad spectrum of substrates across lipid membranes, which play an important role in phase III of the detoxification process. The presence of ABC transporters and their potential association with insecticide resistance have not been investigated in Aphis gossypii, one of the most economically important agricultural pests worldwide. In this study, the ABC transporter inhibitor-verapamil significantly increased thiamethoxam toxicity against resistant cotton aphids, suggesting that ABCs are involved in thiamethoxam resistance. ABC transporter genes were identified using the A. gossypii genome database and transcriptome data. A total of 69 ABC transporters were identified and grouped into seven subfamilies (A-G), including 4 ABCAs, 5 ABCBs, 25 ABCCs, 2 ABCDs, 1 ABCE, 4 ABCFs and 30 ABCGs. Of these ABC transporters, 53 were predicted to be functional, 19 were full transporters, 30 were half-transporters and 4 had two NBDs. Subfamilies C and G accounted for 77% (32 and 45%, respectively) of the genes. The transcripts of 20 of 26 ABCs based on the transcriptome were upregulated, and ABCA1, ABCA2, ABCB1, ABCB4, ABCB8, ABCD1, ABCD2, ABCE1, ABCF1, ABCF3, ABCG7, ABCG15, ABCG17, ABCG24, ABCG27, ABCG30, MRP1, MRP7, MRP14 and MRP21 transcripts were significantly increased in the thiamethoxan resistant strain compared to the susceptible strain with qRT-PCR. The suppression of overexpressed ABCs (ABCA2, ABCD1, ABCD2, ABCE1 and ABCG15) significantly increased the thiamethoxam sensitivity of resistant aphids. These results suggest that ABC transporters might be involved in thiamethoxam resistance in A. gossypii and will facilitate further work to validate the functional roles of these ABCs in thiamethoxam resistance. These results are useful for understanding the multiple resistance mechanisms of thiamethoxam and the management of insecticide-resistant cotton aphids.