Analyses of microRNAs and transcriptomes in the midgut of Spodoptera litura feeding on Brassica juncea

Spodoptera litura is a destructive agricultural pest in tropical and subtropical areas.Understanding the molecular mechanisms of S.litura adaptation to its preferred host plants may help identify target genes useful for pest control.We used high-throughput sequencing to characterize the expression patterns of messenger RNAs(mRNAs)and microRNAs(miRNAs)in the midgut of S.litura fed on Brassica juncea for 6 h and 48 h.A total of 108 known and 134 novel miRNAs were identified,29 miRNAs and 237 mRNAs were differentially expressed at 6 h of B.juncea feeding,26 miRNAs and 433 mRNAs were differentially expressed at 48 h.For the mRNAs,the up-regulated genes were mostly enriched in detoxification enzymes(cytochrome P450,esterase,glutathione^-transferase,uridine diphosphate-glucuronosyl transferase),while the down-regulated genes were mostly enriched in proteinases and immune-related genes.Furthermore,most detoxification enzymes begin to up-regulate at 6 h,while most digestion and immunerelated genes begin to up-or down-regulate at 48 h.Eighteen and 37 differently expressed transcription factors were identified at 6 h and 48 h,which may regulate the functional genes.We acquired 136 and 41 miRNA versus mRNA pairs at 6 h and 48 h,respectively.Some down-regulated and up-regulated miRNAs were predicted to target detoxification enzymes and proteinases,respectively.Real-time quantitative polymerase chain reaction of nine randomly selected miRNAs and 28 genes confirmed the results of RNA-seq.This analyses of miRNA and mRNA transcriptomes provides useful information about the molecular mechanisms of S.litura response to B.juncea.