Overexpression of the ABCG Gene Cluster Contributed to Multi-Insecticide Resistance in <i>Plutella xylostella</i> (L.)

The diamondback moth, <i>Plutella xylostella</i> (L.) (Lepidoptera: Plutellidae), has evolved pronounced resistance to nearly all major classes of insecticides, posing a persistent threat to global agricultural productivity. Although ATP-binding cassette (ABC) transporters are known to contribute to multiple insecticide resistance, their functional significance in <i>P. xylostella</i> remains inadequately elucidated. A genome-wide association study (GWAS) comparing resistant and susceptible strains revealed a genomically clustered trio of ABCG genes (<i>PxABCG4</i>, <i>PxABCG8</i>, <i>PxABCG9</i>) on chromosome 12 that was strongly correlated with the resistance phenotype. Functional characterization through RNAi and CRISPR/Cas9 confirmed that <i>PxABCG4</i> and <i>PxABCG9</i> contribute to resistance against indoxacarb, chlorantraniliprole, and <i>beta</i>-cypermethrin. <i>PxABCG8</i> was implicated in resistance to chlorantraniliprole and <i>beta</i>-cypermethrin in <i>P. xylostella</i>. Furthermore, molecular docking analyses demonstrated high-affinity binding between insecticides and <i>PxABCG4</i>, <i>PxABCG8</i>, and <i>PxABCG9</i>. These findings establish that this ABCG gene cluster constitutes a genetic basis of broad-spectrum insecticide resistance in <i>P. xylostella</i> and provides new insights for understanding the functions of ABCG genes in insects.