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