Comparative transcriptome and metabolome analysis of emamectin benzoate-hyposensitive, and susceptible, strains of Spodoptera frugiperda (Lepidoptera: Noctuidae)

Author of the article:SU Xiang-Ning, LI Chuan-Ying, HUANG Shao-Hua, LIAO Zhang-Xuan, LIU Wei-Ling, ZHANG Yu-Ping

Author's Workplace：Plant Protection Research Institute, Guangdong Academy of Agricultural Sciences, Key Laboratory of Green Prevention and Control of Fruits and Vegetables in South China, Ministry of Agriculture and Rural Affairs, Key Laboratory of High Technology for Plant Protection of Guangdong Province, Guangzhou 510640, China

Key Words：Spodoptera frugiperda; emamectin benzoate; transcriptome; metabolome; detoxification metabolism

Abstract：

[Objectives]  To investigate and clarify the mechanism used by Spodoptera frugiperda to detoxify the insecticide emamectin benzoate. [Methods]  Transcriptome sequencing and metabolomic analysis were performed on 3rd instar S. frugiperda larvae from an emamectin benzoate-hyposensitive strain (EB-HS) and a sensitive strain (SS). The transcriptome and metabolome were analyzed jointly. [Results]  Two hundred and twenty-two differentially expressed genes (DEGs) were detected in the transcriptome, of which 76 were up-regulated and 146 down-regulated (P < 0.05). Among these, eleven metabolism-related genes were more common in the EB-HS than in the SS, and transcript levels were more than 2.0-fold higher in the EB-HS. Identified differential metabolites include uridine diphosphate glucose, L-glutamic acid, gamma- aminobutyric acid, L-threonine and L-cysteine. Gamma-aminobutyric acid was significantly up-regulated with a time difference of 2.47 and L-glutamic acid was significantly down-regulated with a difference multiple of 0.69. The combined analysis of the transcriptome and metabolome indicates that DEGs and DMs are mainly enriched in pentose and glucuronate interconversion, aminoacyl-tRNA biosynthesis, alanine, aspartate and glutamate metabolism, and other pathways. The glutamate metabolic pathway was enriched to four DEGs encoding three key enzymes, including glutamate synthetase, 4-aminobutyrate aminotransferase and glutamate decarboxylase. Four metabolites were enriched by this pathway, which significantly increased aspartic acid, 2-oxoglutarate and gamma-aminobutyric acid content, whereas L-glutamic acid content significantly decreased. Glutamate decarboxylase activity increased in the EB-HS, catalyzing L-glutamate synthesis of the more inhibitory neurotransmitter gamma-aminobutyric acid. [Conclusion]  The glutamate metabolism pathway may play an important role in the detoxification of emamectin benzoate by S. frugiperda. These findings provide a basis for further research on the mechanism responsible for insecticide detoxification in this species.