Sequencing and analysis of complete mitochondrial genome of Holotrichia titanis

【Objective】To determine and analyze the complete sequence mitochondrial genome of Holotrichia titanis,and to explore the phylogenetic relationship of Holotrichia titanis based on the mitochondrial genome sequence which provided scientific basis for revealing the taxonomic status of H. titanis and studying its molecular biology. 【Method】The mitochondrial genome of H. titanis was sequenced by Illumina NovaSeq second generation sequencing technology,and the gene structure characteristics and base composition were analyzed. Based on the protein-coding genes(PCGs) sequence of 17 Coleoptera and 3 Orthopteran outgroups,neighbor-joining and maximum likelihood were used to construct a phylogenetic tree and analyze the phylogenetic relationship between H. titanis and other insects. 【Result】The mitochondrial genome of H. titanis was 16851 bp(accession number MZ726798.1),with a total of 37 genes,including 13 PCGs,22 tRNA genes and 2 rRNA genes,and 1 non-coding control region(D-loop). There were overlapping or gene spacing regions between mitochondrial genome genes,and the AT content in mitochondrial genome accounted for 74.30%,and the base composition showed obvious AT base bias(AT-skew),AT-skew had a positive value and AT-skew bias(GC-skew) had a negative value. Among the PCGs,cox 1 gene had special TTG as the start codon,and the remaining 12 genes had typical ATN as the start codon. In the secondary structures of 22 tRNA genes,except trnS1 gene could not form a complete cloverleaf structure due to the lack of a dihydroouracil(DHU),other tRNA could form a typical cloverleaf structure. The phylogenetic results showed that H. titanis clustered on the same small branch with H. parallela,and they were closely related.【Conclusion】The complete mitochondrial genome sequence of H. titanis is obtained. The mitochondrial genome of H. titanis is consistent with the general characteristics of the mitochondrial genome of Scarabaeidae. H. titanis and H. parallela are very similar in mitochondrial genomics and phylogeny,and have a similar evolutionary history.