Alternative splicing of a carboxyl/choline esterase gene enhances the fenpropathrin tolerance of Tetranychus cinnabarinus.

Detoxification plays a crucial role in agricultural pests to withstand the pesticides, and cytochrome P450s, carboxyl/cholinesterases (CCEs), and glutathione-S-transferases are the main proteins responsible for their detoxification ability. The activity of CCEs can be up-regulated, down-regulated, or modified by mutation. However, few studies have examined the role of alternative splicing in altering the properties of CCEs. We identified two variants of TcCCE23 in Tetranychus cinnabarinus: a long version (CCE23-V1) and a short version that is 18 nucleotides shorter than CCE23-V1 (CCE23-V2). Whether splicing affects the activity of TcCCE23 remains unclear. Overexpression of CCE23-V2 in fenpropathrin resistant T. cinnabarinus revealed that splicing affected the detoxification of fenpropathrin by CCE23-V2. The mortality of mites was significantly higher when the expression of CCE23-V2 was knocked down (43.2% ± 3.3%) via injection of CCE23-dsRNA compared with the control group injected with GFP-dsRNA under fenpropathrin exposure; however, the down-regulation of CCE23-V1 (61.3 ± 6.3%) by CCE23-siRNA had no such effect, indicating CCE23-V2 plays a greater role in xenobiotic metabolism than CCE23-V1. The tolerance of flies overexpressing CCE23-V2 to fenpropathrin (LD 50 = 19.47 μg/g) was significantly higher than that of Gal4/UAS-CCE23-V1 transgenic flies (LD 50 = 13.11 μg/g). Molecular docking analysis showed that splicing opened a "gate" that enlarge the substrate binding cavity of CCE23-V2, which might enhance the ability of CCE23-V2 to harbor fenpropathrin molecules. These findings suggest that splicing might enhance the detoxifying capability of TcCCE23. Generally, our data improve the understanding of the diversity and complexity of the mechanisms underlying the regulation of CCEs. This article is protected by copyright. All rights reserved.