Construction Of DNA Barcode Of Carangidae And Assembly And Analysis Of Pseudocaranx Dentex Genome

In order to provide molecular biological evidence for the systematic classification and species identification of Carangidae,and to verify the applicability of COI as a barcode in the identification of Carangidae worldwide,this work collected 5 genera and14 species from coastal areas of China.The COI of all Carangidae,combined with the259 of 89 species in 24 genera,screened and downloaded from the BOLD database,total 273 of 95 species in 25 genera,were calculated by calculating their distances between genes,distances between species and distances within species,constructing Neighbor joining(NJ)and Maximum parsimony(MP)phylogenetic tree.The results showed that the average levels of the different classification of the 273 Carangidae were0.186,0.169,and 0.008 respectively,respectively.The average genetic distance between species was 21 times that of the average within species,and 95 species form 4monophyletic branches(subfamily)in the phylogenetic tree,with clear boundaries,and the clustering effect of species of the same genus is also ideal.The research enriched the Carangidae DNA barcode database,provided molecular biology evidence for Carangidae identification and systematic taxonomy and verified the applicability and validity of the COI as a DNA barcode in Carangidae identification.In inaddition,to explore molecular mechanisms such as species inheritance and evolution at the genomic level,this work uses Pseudocaranx dentex as the research object,using Illumina and Pacbio sequencing data,combined with various auxiliary assembly technologies such as HI-C,a high-quality genome map of the P.dentex was generated,and the genome was annotated and comparative genome analysis was performed at the same time.The results showed that the genome size of the P.dentex was 636.82 Mb,of which 631.48 Mb was anchored to 24 chromosomes,accounting for 99.16%;the contig and scaffold N50 reached 25.60 Mb and 28.04 Mb,respectively;the Illumina read ratio was 99.23% and the coverage rate was about99.48%,,the evaluation results of CEGMA and BUSCO reached 98.39% and 98.30%,respectively.Through annotation,a total of 23,208 protein-coding genes were predicted,of which 23,149 genes were successfully annotated,accounting for 99.7%.Comparative genome analysis showed that the P.dentex diverged from its nearest ancestor,seriola,65.7 million years ago.Many gene families,such as various types of proteins and enzyme activities,show an obvious trend of expansion,and some genes are also subject to strong positive selection,which may be related to their specific biological characteristics.The high-quality genome obtained in this study has enriched the genomic information of Carangidae and provided valuable resources for the study of characteristic biological problems of Carangidae.At the same time,the partial interpretation of the genome will also contribute to provide useful methods and ideas of P.dentex in immune resistance,Molecular breeding and genetic improvement,etc.