The Study On Response Of The Asian Corn Borer,Ostrinia Furnacalis To Environmental Toxins And The Molecular Mechanism Of Its Detoxification

Insects are often stressed by environmental toxins such as heavy metals and plant secondery compounds during growth and development.To explore the response and the molecular mechanism by which insects detoxify environmental toxins,we tested the physiological response and the molecular mechanism that the heavy metal cadmium(Cd)affects the communication system in Asian corn borer(ACB),Ostrinia furnacalis by using the third-generation full-length transcriptome sequencing technology and the next-generation sequencing technology in our study.In addition,combining with the data of genomes and transcriptomes in insects,we annotated two detoxifying enzyme families,metallothioneins(MTs)and P450.The results were as follow:1,we found that Cd was mainly accumulated in the digestion tract of larvae,and it was mainly excreted out of body by excrement,silk,pupal case and molt of larvae to reduce toxicity in the body.2,we found that sex pheromone titer of female adult in Asian corn borer were decreased in Cd treatment.To determine the molecular mechanisms of the effects regulated sex pheromones communication,a RNA-seq comparison transcriptome was used in our study.We found that there were 123 differentially expressed genes in heavy metal Cd treatment,which including in 122 up-regulated genes and 1 down-regulated gene.The analysis of the metabolic pathways of 123 differential genes showed that two differential genes are involved in the synthesis and metabolic pathways of fatty acids.Previous studies have showed that the synthesis of sex pheromones is closely related to the synthesis and metabolism of fatty acids in moth species.In addition,the synthesis of sex pheromone components is derived from fatty acids and amino acids.Therefore,these two differentially expressed genes may be the key genes that involved in the molecular mechanism of heavy metal Cd affect sex pheromone communication system in the ACB.3,we identified and cloned the pheromone biosynthesis activating neuropeptide receptor(PBANR)gene,which regulated the production and release of sex pheromones in the ACB.The O.furnacalis PBANR(Ostfu PBANR)gene has an ORF of 1,086 bp and encoded 362 amino acids.Expression analysis showed that Ostfu PBANR was highly expressed in the pheromone glands compared with other tissues.Interestingly,Ostfu PBANR was expressed higher in the larval stages compared to the pupal or adult stages,suggesting that Ostfu PBANR may have broad functions in larva beyond adult pheromone synthesis.4,we identified 259 putative insect MTs from 14 orders and 120 insect species.Via the evolution analysis of 75 MTs from Lepidoptera insects,we found that these 75 MTs were clustered in three branches,and we named Lep MT?,Lep MT? and Lep MT? families.In addition,we identified 4 MTs of O.furnacalis,which could help us to determine how O.furnacalis detoxify HMs.5,we annotated and identified the P450 genes of three Ostrinia species by bioinformatics methods.The numbers of P450 s in ACB,ECB and ABB were 79,78 and80 respectively.By comparing the number and evolutionary relationship of the CYP Clan3 gene family of three closely related species,10 CYP genes of ACB and ECB were clustered together in the phylogenetic tree construction,and 6 CYP genes only appeared in ACB and ECB,but not exist in ABB.These 16 candidate P450 genes may be involved in the detoxification of plant secondary metabolite and evolution of host adaption in ACB.In this study,we studied the molecular mechanism that the heavy metal cadmium(Cd)affects the communication system in ACB.In addition,we annotated two detoxification gene families,MT and P450,which involved in the detoxification of heavy metals and plant secondary metabolite.Our results are very important for determining the molecular mechanism of how ACB response the environmental toxins such as heavy metal Cd and host secondary metabolite.