Genetic Characteristics And Environmental Adaptation Mechanism Of Neptunea Cumingii Population Based On Simplified Genome And Transcriptome Technology

Naptunea cumingii is a very important marine economic shellfish in the Yellow Sea,Bohai Sea,North Korea and Japan.However,due to factors such as overfishing and global warming,the resource of coastal snails is facing a decline in China.In this study,there are 6 sea snails.The morphological comparison method,simplified genome and transcriptome techniques were used to obtain high-density SNP loci at the genome level.Based on the genetic diversity level of snails,the genetic variation pattern of environmental adaptability was inferred,and the genetic structure of snail populations was analyzed from a new perspective.In addition to the analysis of population genetic structure,adaptive evolution has also been a hotspot in evolutionary ecology research in recent decades.Local adaptation refers to certain characteristics of local groups that make them better adapted to the local environment than foreign groups.It has long been generally accepted that adaptive evolution is a slow process that requires accumulation over a long period of time,so it may not have an impact on current ecological processes.Through transcriptome sequencing technology,genes related to environmental adaptation were screened,and the genetic mechanism of environmental adaptation in different geographical groups at the transcriptome level was deeply explored.The relevant research results have important scientific significance for clarifying the genetic diversity level and germplasm genetic background of snails,and for in-depth understanding of the genetic mechanism of snail environmental adaptation,and have important guiding value for the restoration and management of snail resources.The main results are as follows:1.Multivariate statistical analysis was carried out on the quantifiable traits of 180 snails from 6 different geographical populations.Principal component analysis results showed that the cumulative contribution rates of spiral height/shell height(A),body height/shell height(B)and shell mouth width/shell height(C)reached 94.210%.Both principal component analysis and cluster analysis showed that WH group was a separate group.The results of discriminant analysis showed that comprehensive discriminant accuracy(47.5%).The results of one-way an OVA showed that ZZ and WH,YT and WH,HS and WH,LS and WH,PL and WH,HS and LS and HS and LS had 8 significant indexes.The results showed that the morphological characteristics of WH population were different from those of other populations,which may be related to environmental factors such as latitude,water temperature or nutrients.2.Based on simplified genome sequencing(GBS),83 individuals collected from 6physical geographic groups in the Yellow Sea and Bohai Sea were analyzed.After quality control filtering,a total of 1992 discrete loci(SNPs)were obtained for population genomics analysis.The observed heterozygosity of the six snail populations was 0.1551~0.1612,the expected heterozygosity was 0.1064~0.1117,and the nucleotide diversity was 0.1120~0.1241.ARLEQUIN calculates Fst in the range-0.04683 to-0.02041.AMOVA analysis showed that 0.27 % of the genetic differences came from between groups,and 100.80% of the genetic differences came from within groups.A total of 331 discrete loci were screened by two Fst values and a method associated with environmental factors.Functional annotation showed that the genes located at these discrete loci were involved in cell composition and biological processes,including growth and development,cell metabolism and catalysis Activity and other correlations,indicating that different groups of snails can detect signals related to local fitness..3.Through the transcriptome sequencing analysis of snail gill tissues under the four temperature treatments of spring,summer,autumn and winter,after quality control,the YT and ZZ populations have the most in winter,which are 7.04 G and 6.92 G,respectively.The data volume of other snails in different seasons is above 6G.GO annotation was performed on genes,among which cellular process,metabolic process,binding,and catalytically active genes were the most numerous.KEGG analysis showed that the pathways involved in snail immunity and stress included MAPK signaling pathway,TGF-beta signaling pathway,two-component system,JAK-STAT signaling pathway,Fox O signaling pathway,NF-κB signaling pathway and other pathways.From the differential expression analysis,it can be seen that ZZ_Dvs ZZ_X has the largest number of differentially expressed genes,with 5461 up-regulated genes and 4582 down-regulated genes;ZZ_Qvs ZZ_X has the least number of differentially expressed genes,with 1735 up-regulated genes and 1775down-regulated genes.YT_Dvs YT_X has the largest number of differentially expressed genes,20909,including 9503 up-regulated genes and 11406down-regulated genes;YT_Cvs YT_X has the least number of differentially expressed genes,7842,of which the number of up-regulated genes is 5160 and the number of down-regulated genes is 2682 strip.Eight key genes of MAPK signaling pathway,FASL,PKA,MEKK1,MKK3,MP1,ERK and PPP3 C,were up-regulated in ZZ population.Eleven key genes including PKA,ERK and MEKK were up-regulated in YT population.The Toll signaling pathway contained 7 up-regulated genes including TOLLIP,P13 K and ERK in ZZ population,and 5 key genes were up-regulated in YT population.q PT-PCR analysis showed that the expression trend of 11 differentially expressed genes related to immune stress was similar to RNA-seq expression profile.