| It is important to understand the diapause characteristics of insects for pest population control.The fall webworm,Hyphantria cunea(Drury)is a severe invasive pest and has caused significant damages to forests and diversity of species.At present,the biological characteristics and molecular regulation mechanism of diapause induction of H.cunea are still unclear.The effects of photoperiod and temperature on the diapause induction in H.cunea were investigated in this paper,and main factors controlling the diapause induction of H.cunea were determined.The larval instars sensitive to photoperiod induced diapause was determined by switch photoperiod treatment experiments.Transcriptome dynamic changes of sensitive stages between non-diapause and diapause induction were compared.Genes potential and KEGG pathway related to diapause induction were screened through pathway analysis.The main results are listed as follows:1.The results indicated that the H.cunea is a typical kind of short-photoperiod diapause insect,and the photoperiod play a crucial role in the process of diapause induction,and temperature is the cofactor of diapause induction.Low temperature and short photoperiod tended to diapause,and the critical photoperiod shortened with the rising of temperature.The critical photoperiod were 14 h 58 min: 9 h 02 min(L:D),14 h 45 min: 9 h 15 min(L:D),14 h 35 min: 9 h 25 min(L:D)and 14 h 24 min: 9 h 36min(L:D)at 21,23,25 and 27 ℃,respectively.It was revealed that 3-5 instar of H.cunea larvae were the most sensitive developmental stage to the short photoperiod induced diapause.2.Here we used high-throughput RNA-Seq to identify candidate genes and processes linked to diapause induction by comparing the transcriptome differences between the most sensitive larval brains developmental stage of diapause(L10:D14)and non-diapause(L16:D8).The reference sequence of the transcriptome was reassembled to obtain 56455 Unigenes.After sequencing and filtering,a total of20,935 sequences(37.08%)were annotated in 8 public databases.According to the annotations,Nr database had the largest match(19,853,35.17%),the top match was obtained by Spodoptera litura,with 3,110 sequences(15.68%).10,432 unigenes were categorized into 52 sub-categories GO categories.In GO functional groups,most of the cell component are cell and cell part.In the molecular function group,most genes belong to the binding and catalytic activity.metabolic process and cellular processes are dominant in biological process groups.A total of 9,938 unigenes were annotated against KEGG database and assigned to 228 pathways.Ribosome is the most involved metabolic pathway.Several functional terms related to ECM-receptor interaction,Cellular detoxification,Insect hormone biosynthesis,Energy metabolism and other metabolic pathways were enriched during the most sensitive induction period.these metabolic pathways play an important role in the diapause induction of H.cunea.The expression and regulation of Circadian rhythm,Signal transduction and Environmental adaptation signaling pathway related genes were differentially expressed in diapause.Among them,Glucose dehydrogenase,Glutathione-S-transferase,Juvenile hormone acid methyltransferase,Heat shock protein,Take out play important role in insect diapause regulation.In this study,the effects of photoperiod and temperature on diapause induction of H.cunea were elucidated.The photoperiod plays a crucial role in the process of diapause induction of H.cunea.We identified the genes and metabolic pathway related to diapause induction.This study enriches the study of insect diapause and lays a foundation for understanding of the molecular mechanism of insect diapause and its regulation. |
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