Abstract
Here, we determined the nearly complete mitochondrial genome (mitogenome) of Chrysochares punctatus (Coleoptera: Chrysomelidae: Eumolpinae), an important insect pest on Apocynum venetum in Northwestern China. This mitogenome was 14,451 bp long, encoding 13 protein-coding genes (PCGs), 21 transfer RNA genes (tRNAs), and 2 ribosomal RNA genes. The C. punctatus mitogenome presented an A + T content of 75.11%, with a positive AT-skew (0.064) and a negative GC-skew (−0.192). Ten PCGs started with a typical ATN codon, whereas the remaining three PCGs started with AAC (cox1) and TTG (nad1 and nad2). All tRNAs had a typical secondary cloverleaf structure, except for trnS1 which lacked the dihydrouridine arm. Bayesian phylogenetic analysis based on the nucleotide sequences of 13 PCGs recovered a phylogeny within Chrysomelidae: (((Chrysomelinae + Galerucinae), (((Eumolpinae, Lamprosomatinae), Cassidinae), Criocerinae)), Bruchinae).
Keywords: Insects, leaf beetles, mitochondrial DNA, phylogeny
Chrysochares punctatus (Coleoptera: Chrysomelidae: Eumolpinae) is an important insect pest on Apocynum venetum (Gentianales: Apocynaceae). Here, we sequenced and annotated the mitochondrial genome (mitogenome) of C. punctatus. Adult specimens were collected from Altay City (87.55°E, 47.71°N), Xinjiang Uygur Autonomous Region, China, in July 2018. All samples (LZUALT45) have been deposited in the State Key Laboratory of Grassland Agro-Ecosystems, College of Pastoral Agricultural Science and Technology, Lanzhou University, Lanzhou, China. The total genomic DNA was extracted from a single specimen (LZUALT45_1) using a DNeasy Tissue Kit (Qiagen). The C. punctatus mitogenome was amplified with a set of universal and specific primers, and sequenced in both directions, following the method of our previous study (Yuan et al. 2016).
The nearly complete mitogenome of C. punctatus was 14,451 bp long (GenBank accession number MN745103). This mitogenome contained 13 protein-coding genes (PCGs), 21 transfer RNA genes (tRNAs), and 2 ribosomal RNA genes (rrnL and rrnS). The order and orientation of the mitochondrial genes were identical to the inferred ancestral arrangement of insects (Boore 1999). Gene overlaps were found at seven gene junctions and involved a total of 27 bp; the longest overlap (8 bp) existed between trnW and trnC. A total of 29 bp intergenic spacers were present in seven positions, ranging in the size from 1 bp to 17 bp.
The nucleotide composition of the C. punctatus mitogenome was biased toward A and T with an A + T content of 75.11% in J-strand. This mitogenome presented a positive AT-skew (0.064) and a negative GC-skew (−0.192), as found in most insect mitogenomes. The rrnL was 1265 bp long with an A + T content of 80.24% and the rrnS was 744 bp with an A + T content of 77.28%. Among the 13 PCGs, the lowest A + T content was 67.19% in cox1, while the highest was 84.31% in atp8. Ten PCGs started with a typical ATN codon: two (cox2, nad6) with ATC, two (atp8, nad5) with ATT, two (nad1, nad2) with TTG, five (atp6, cox3, nad4, nad4L, cob) with ATG. The remaining two PCGs began with AAC (cox1) or ATA (nad3). Five PCGs terminated with a complete end codon TAA, whereas the remaining eight terminated with an incomplete stop codon TA or T. All of the 21 tRNAs, ranging from 61 bp (trnA) to 71 bp (trnK), had a typical cloverleaf structure, except for trnS1 which lacked the dihydrouridine arm.
The concatenated nucleotide sequences of 13 PCGs from 35 leaf beetles and two outgroups (Anoplophora glabripennis and Batocera lineolata) from Cerambycidae were used for phylogenetic analysis, using RAxML-HPC2 on the CIPRES Science Gateway 3.3 (Miller et al. 2010). The maximum likelihood tree strongly supported a closer relationship between C. punctatus and Chrysodinopsis sp. from the same subfamily Eumolpinae (Figure 1). Phylogenetic relationships among subfamilies were recovered as (((Chrysomelinae + Galerucinae), (((Eumolpinae, Lamprosomatinae), Cassidinae), Criocerinae)), Bruchinae).
Figure 1.
Mitochondrial phylogeny of 35 Chrysomelidae species based on the concatenated nucleotide sequences of 13 mitochondrial protein-coding genes. Bootstrap values less than 50 are not shown on the branch.
Funding Statement
This study was funded by the Program for Changjiang Scholars and Innovative Research Team in University [IRT_17R50], the Science and Technology Project of the Xinjiang Uygur Autonomous Region, China [2016E02015 and 2016A03006], and the Key Project at Central Government Level: The Ability Establishment of Sustainable Use for Valuable Chinese Medicine Resources [2060302].
Disclosure statement
The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.
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