Comparative mitochondrial genomes of four species of Sinopodisma and phylogenetic implications (Orthoptera, Melanoplinae)

Abstract

In this study, the whole mitochondrial genomes (mitogenomes) from four species were sequenced. The complete mitochondrial genomes of Sinopodisma pieli, S. houshana, S. qinlingensis, and S. wulingshanensis are 15,857 bp, 15,818 bp, 15,843 bp, and 15,872 bp in size, respectively. The 13 protein-coding genes (PCGs) begin with typical ATN codons, except for COXI in S. qinlingensis, which begins with ACC. The highest A+T content in all the sequenced orthopteran mitogenomes is 76.8% (S. qinlingensis), followed by 76.5% (S. wulingshanensis), 76.4% (S. pieli) and 76.4% (S. houshana) (measured on the major strand). The long polythymine stretches (T-stretch) in the A+T-rich region of the four species are not adjacent to the trnI locus but are inside the stem-loop sequences on the major strand. Moreover, several repeated elements are found in the A+T-rich region of the four species. Phylogenetic analysis based on 53 mitochondrial genomes using Bayesian Inference (BI) and Maximum Likelihood (ML) revealed that Melanoplinae (Podismini) was a monophyletic group; however, the monophyly of Sinopodisma was not supported. These data will provide important information for a better understanding of the phylogenetic relationship of Melanoplinae.

Keywords: Sinopodisma; mitogenome; phylogeny.

Figure 1.

Circular map of the mitogenome from four species.

Figure 2.

The relative synonymous codon frequencies from the four species.

Figure 3.

The long polythymine stretch and conserved sequence blocks in the A+T rich regions from four species. Note: The long polythymine stretch. T-stretch sequence was labelled with box, located in the majority strand. Within each block, nucleotides identical in the two sequences are bottom-marked with asterisks.

Figure 4.

The main repeat elements in A+T-rich regions from four species.

Figure 5.

The phylogenetic tree based on 37 mitochondrial genes. (A) ML tree; (B) BI tree.