Midgut transcriptome response to a Cry toxin in the diamondback moth, Plutella xylostella (Lepidoptera: Plutellidae)

To investigate the response of Plutella xylostella transcriptome in defending against a Bt toxin, high-throughput RNA-sequencing was carried out to examine Cry1Ac-susceptible and -resistant strains. The comparative analysis indentified over 2900 differentially expressed unigenes (DEUs) between these two strains. Gene Ontology analysis placed these unigenes primarily into cell, cell part, organelle, binding, catalytic, cellular process, metabolic process, and response to stimulus categories. Based on pathway analyses, DEUs were enriched in oxidoreductase activity and membrane lipid metabolic processes, and they were also significantly enriched in pathways related to the metabolic and biosynthesis of secondary metabolites. Most of the unigenes involved in the metabolic pathway were up-regulated in resistant strains. Within the ABC transporter pathway, majority of the down-regulated unigenes belong to ABCC2 and ABCC10, respectively, while up-regulated unigenes were mainly categorized as ABCG2. Furthermore, two aminopeptidases, and four cadherins encoding genes were significantly elevated as well. This study provides a transcriptome foundation for the identification and functional characterization of genes involved in the Bt resistance in an agriculturally important insect pest, P. xylostella.