Transcriptome analysis and identification of P450 genes relevant to imidacloprid detoxification in Bradysia odoriphaga

Abstract

Pesticide tolerance poses many challenges for pest control, particularly for destructive pests such as Bradysia odoriphaga. Imidacloprid has been used to control B. odoriphaga since 2013, however, imidacloprid resistance in B. odoriphaga has developed in recent years. Identifying actual and potential genes involved in detoxification metabolism of imidacloprid could offer solutions for controlling this insect. In this study, RNA-seq was used to explore differentially expressed genes in B. odoriphaga that respond to imidacloprid treatment. Differential expression data between imidacloprid treatment and the control revealed 281 transcripts (176 with annotations) showing upregulation and 394 transcripts (235 with annotations) showing downregulation. Among them, differential expression levels of seven P450 unigenes were associated with imidacloprid detoxification mechanism, with 4 unigenes that were upregulated and 3 unigenes that were downregulated. The qRT-PCR results of the seven differential expression P450 unigenes after imidacloprid treatment were consistent with RNA-Seq data. Furthermore, oral delivery mediated RNA interference of these four upregulated P450 unigenes followed by an insecticide bioassay significantly increased the mortality of imidacloprid-treated B. odoriphaga. This result indicated that the four upregulated P450s are involved in detoxification of imidacloprid. This study provides a genetic basis for further exploring P450 genes for imidacloprid detoxification in B. odoriphaga.

Identification of a novel cytochrome P450 CYP3356A1 linked with insecticide detoxification in Bradysia odoriphaga

“…In our previous transcriptome data for B. odoriphaga , a partial sequence of cytochrome P450 was identified . To obtain the full‐length cDNA, 5′‐ and 3′‐rapid amplification of cDNA ends (RACE) was performed using a 3/5‐RACE kit according to the manufacturer's instructions (Clontech, Dalian, China).…”

“…In a previous study, we reported that enhanced P450 enzyme activity and elevated P450 gene expression were related to insecticide resistance in B. odoriphaga , but no reports on the properties of specific completed P450 genes and the related insecticide resistance mechanism in this pest have been found. Therefore, in this study, a full‐length cDNA encoding P450 of B. odoriphaga CYP3356A1 was cloned and used for further functional analysis.…”

“…The primary mode of action of pyrethroids is to disrupt voltage‐sensitive sodium channel function, and pyrethroids such as β‐cypermethrin are widely used in the control of many insect pests, including dipterans . Generally, applying insecticides, such as imidacloprid, thiamethoxam, chlorpyrifos and β‐cypermethrin, is the main method of pest control in Chinese chives . Yield losses for Chinese chive could reach > 50% in the absence of insecticide protection against B. odoriphaga …”

Selection of reference genes for quantitative real‐time polymerase chain reaction normalization inBradysia odoriphaga(Diptera: Sciaridae)

“…; Chen et al . ). Therefore, a comprehensive evaluation of suitable reference genes is of high importance in B. odoriphaga .…”

“…In recent years, research on B. odoriphaga has mainly focused on biological characteristics and chemical control methods and on its physiology and biochemistry (Zhao et al 2016;Gao et al 2016b). The RT-qPCR technique has been the main technical method used in these investigations (Gao et al 2016a;Chen et al 2018). Therefore, a comprehensive evaluation of suitable reference genes is of high importance in B. odoriphaga.…”