Functional analysis of SDR112C1 associated with fenpropathrin tolerance in Tetranychus cinnabarinus (Boisduval)

Short-chain dehydrogenases/reductases (SDRs) are ubiquitously distributed across diverse organisms and play pivotal roles in the growth, as well as endogenous and exogenous metabolism of various substances, including drugs. The expression levels of SDR genes are reportedly upregulated in the fenpropathrin (FEN)-resistant (FeR) strain of Tetranychus cinnabarinus. However, the functions of these SDR genes in acaricide tolerance remain elusive. In this study, the activity of SDRs was found to be significantly higher (2.26-fold) in the FeR strain compared to the susceptible strain (SS) of T. cinnabarinus. A specific upregulated SDR gene, named SDR112C1, exhibited significant overexpression (3.13-fold) in the FeR population compared with that in the SS population. Furthermore, the expression of SDR112C1 showed a significant increase in the response to FEN induction. Additionally, knockdown of the SDR112C1 gene resulted in decreased SDR activity and reduced mite viability against FEN. Importantly, heterologous expression and in vitro incubation assays confirmed that recombinant SDR112C1 could effectively deplete FEN. Moreover, the overexpression of the SDR112C1 gene in Drosophila melanogaster significantly decreased the toxicity of FEN to transgenic fruit flies. These findings suggest that the overexpression of SDR SDR112C1 is a crucial factor contributing to FEN tolerance in T. cinnabarinus. This discovery not only enhances our understanding of SDR-mediated acaricide tolerance but also introduces a new family of detoxification enzymes to consider in practice, beyond cytochrome P450s, carboxyl/choline esterases and glutathione S-transferases.