Transcriptomesof The Tigrina Swallowtail Luehdorfia Chinensis And Evolutionary Analyses Forchemosensory Genes

Luehdorfia chinensis is one of the rare and threatened butterflies in the world,which only distributed in parts of Qinling region and the Yangtze River in China,and is a second class national-level protected animal.It is crucial to protect L.chinensis population for its rapid decrease of wild population recent years.L.chinensis is an obligate parasitic insect which feeds on Asarum sieboldii and Asarum forbesii.Chemoreception is a biological process essential for the survival of insect,as it allows the recognition of important volatile cues for the detection of food,egg-laying substrates,mates and so on.This key role in several vital biological processes makes chemoreception a particularly interesting system for studying the role of natural selection in molecular adaptation.Interactions between insects and plants are mediated by various chemoreceptors,such as olfactory receptor(Or),gustatory receptor(Gr),odorant binding protein(OBP),chemosensory protein(CSP)and ionotropic receptor(IR).Here,we sequenced the transcriptomes of L.chinensis using next generation sequencing technologies to detection their molecular mechanism of chemoreception.The main results and conclusions are as follows:1)Approximately 45 million clean reads were generated for each sample on average using high-throughput sequencing.All sequences were assembled in 175,641 contigs and 110,007 final UniGenes,and a total of 26,137 UniGenes were annotated,with an average of 23.76%,which indicates that a large number of transcriptsstill need to be annotated.Based on genome homologyanalysis,a total of 43,825 sequences were assigned to 61 clusters of gene ontology(GO),in which the "cellular process","metabolic process" and "single-organism process" occupya major proportion.According to statistics,a total of 13,524 UniGenes were assigned to 25 clusters of orthologous groups(COG),in which the "Signal transduction mechanisms" makes up the largest proportion(a total 7,178 sequences,about 9.2%).We found a total of 5,718 genes and 296 metabolic pathways in the Kyoto Encyclopedia of Genes and Genomes(KEGG).A total of 17,635 potential SSRs and 7,908 high quality of SNPs were identified.2)In the transcriptome of L.chinensis we identified 25 Ors,18 Grs,8 OBPs,10 CSPs and 11 IRs.Among these genes,we found CSP12?Gr11 and OBP5 have specific expression.We speculate that the CSP12 may related to detection of egg-laying substrates for is female-specific expression.The Grll and OBP5 mainly express in antenna and maxillary palp,which validates that the insects major organs to detect scents and pheromone mainly enriched in the head.3)According to the phylogenetic analysis of chemoreception genes,we found that the LchiOr13,LchiOr14,LchiOr24,LchiOr35 and LchiOr41 are more original.The olfactory receptor(Or)gene of L.chinensis and Heliconius melpomene have closed relationship,and this is also in accordance with odorant binding protein(OBP)gene.In the gustatory receptor(Gr),LchiGr63 is more original than others.In the ionotropic receptors(IR)tree,LchiIR may be the most original gene.In summary,we generated the most comprehensive transcriptome data for L.chinensis,successfully assembled the transcriptome without reference genome information.Our results will provide an extensive resource for investigating the chemoreceptor complement of this rare and threatened butterfly,and some new clues for the study of genes of feeding mechanisms and critical senses.