Characterization and phylogenetic analysis of the complete mitochondrial genome of Aphis spiraecola (Hemiptera: Aphididae).

Aphis spiraecola is an important pest of citrus and transmits a number of plant viruses. Here, we sequenced and annotated the complete mitochondrial genome (mitogenome) of A. spiraecola. This mitogenome was 15,465 bp long and encoded 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), and 2 ribosomal RNA unit genes (rRNAs). Gene order was conserved and identical to that of Drosophila yakuba and to most other previously sequenced Aphididae. The whole mitogenome exhibited heavy AT nucleotide bias (81.8%). All 13 PCGs were initiated by the ATN (ATG, ATT and ATA) codon. Except for cox1 and nad4 which end with the incomplete codon T-, all PCGs terminated with the stop codon TAA. Phylogenetic analysis showed that A. spiraecola got together with the same genus species Aphis gossypii and Aphis craccivora with high support value, and Aphis had a close relationship with Schizaphis and Rhopalosiphum.

The spirea aphid, Aphis spiraecola Patch (Hemiptera: Aphididae), is a pest of citrus and is a vector of citrus tristeza virus (CTV) (Yokomi and Tang 1995; Tsai and Wang 2001). Aphis spiraecola originated from eastern Asian origin and has a worldwide distribution, which can also damage apples, ornamentals, and pears (Blackman and Eastop 2000; Cao et al. 2012).

Specimens of A. spiraecola were collected from Xinyu City, Jiangxi Province, China (27°52′N, 114°55′E, May 2019) and were stored in Entomological Museum of Gannan Normal University (Accession number GNU-AS039). After morphological identification, total genomic DNA was extracted from tissues using DNeasy DNA Extraction kit (Qiagen, Valencia, CA). Mitogenome sequence was generated using Illumina HiSeq 2500 Sequencing System (Illumina, San Diego, CA). In total, 5.7 G raw reads were obtained, quality-trimmed and assembled using MITObim v 1.7 (Hahn et al. 2013). By comparison with the homologous sequences of other Aphididae species from GenBank, the mitogenome of A. spiraecola was annotated using software GENEIOUS R8 (Biomatters Ltd., Auckland, New Zealand).

The complete mitogenome of A. spiraecola is 15,465 bp (Genbank accession, MN316642). It contains 13 protein-coding genes (PCGs), 22 tRNA genes, 2 rRNA genes, and a non-coding AT-rich region. Gene order was conserved and identical to that of Drosophila yakuba and to most other previously sequenced Aphididae (Thao et al. 2004; Ren et al. 2016; Li et al. 2017; Chen et al. 2019). The nucleotide composition of the mitogenome was biased toward A and T, with 81.8% of A + T content (A 45.1%, T 38.9%, C 10.2%, G 5.8%). Of the 13 PCGs, 4 PCGs (nad4, nad4l, nad5, and nad1) were encoded by the minority strand (N-strand) while the other nine were located on the majority strand (J-strand). All PCGs started with the standard ATN codons (eight ATT, three ATA, and two ATG). Most of the PCGs terminated with the TAA stop codon, while an incomplete stop codon T − was found in two genes (cox1 and nad4). The 22 tRNA genes vary from 62 bp (trnW, trnT, and trnV) to 73 bp (trnK). Two rRNA genes (rrnL and rrnS) locate at trnL1/trnV and trnV/control region, respectively. The lengths of rrnL and rrnS in A. spiraecola are 1263 and 775 bp, with the AT contents of 85.4 and 84.5%, respectively.

Phylogenetic tree was constructed using the maximum-likelihood method through raxmlGUI 1.5 (Silvestro and Michalak 2012) based on 13 mitochondrial protein-coding genes sequences (Figure 1). Results showed that the new sequenced species A. spiraecola got together with the same genus species Aphis gossypii and Aphis craccivora with high support value (BS = 97), and Aphis had a close relationship with Schizaphis and Rhopalosiphum. In conclusion, the mitogenome of A. spiraecola is obtained in this study and can provide essential and important DNA molecular data for further phylogenetic and evolutionary analysis of Aphididae.

Figure 1.

Phylogenetic relationships based on the 13 mitochondrial protein-coding genes sequences inferred from RaxML. Numbers on branches are Bootstrap support values (BS).