|WALSH, THOMAS - Commonwealth Scientific And Industrial Research Organisation (CSIRO)|
Submitted to: Journal of Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/7/2016
Publication Date: 4/1/2016
Citation: Perera, O.P., Walsh, T.K., Luttrell, R.G. 2016. Complete mitochondrial genome of Helicoverpa zea (Boddie) and expression profiles of mitochondrial-encoded genes in early and late embryos. Journal of Insect Science. 16(1):40. 1–10. doi: 10.1093/jisesa/iew023.
Interpretive Summary: Mitochondrial genomes (mt genomes) are evolutionarily highly conserved within a species and frequently used in deriving evolutionary relationships. Conserved sequences within mt genomes also used in identification of morphologically similar species and cataloguing animal and plant species (e.g. barcode of life project). Here, the mitochondrial genome sequence of the bollworm, Helicoverpa zea, was characterized using next generation sequencing and compared with related species such as Helicoverpa armigera and H. punctigera. Gene organization of H. zea mt genome was identical to other lepidopteran mt genomes. Nucleotide composition of the H. zea mitogenome was very similar to those of the related species H. armigera and H. punctigera. Mapping of RNA-Seq reads obtained from 2-hour eggs and 48-hour embryos to protein coding genes (PCG) revealed that all H. zea PCGs were processed as single mature gene transcripts except for the bicistronic atp8/atp6 transcript. A palindromic nucleotide sequence identified in the mt genome of H. zea may be involved in starting gene transcription and mt genome replication.
Technical Abstract: The mitochondrial genome of the bollworm, Helicoverpa zea, was assembled using paired-end nucleotide sequence reads generated with a next-generation sequencing platform. Assembly resulted in a mitogenome of 15,348 bp with greater than 17,000-fold average coverage. Organization of the H. zea mitogenome (gene order and orientation) was identical to other known lepidopteran mitogenome sequences. Compared to Helicoverpa armigera mitogenome, there were a few differences in the lengths of gaps between genes, but the lengths of nucleotide overlaps were essentially conserved between the two species. Nucleotide composition of the H. zea mitogenome was very similar to those of the related species H. armigera and H. punctigera. Mapping of RNA-Seq reads obtained from 2-hour eggs and 48-hour embryos to protein coding genes (PCG) revealed that all H. zea PCGs were processed as single mature gene transcripts except for the bicistronic atp8/atp6 transcript. A tRNA-like with a predicted hammer-head like secondary structure and with a potential role in transcription start and mtDNA replication was identified within the control region of the H. zea mitogenome. Similar structures were also found within the control regions of several other lepidopteran species. Expression analysis did not reveal significant differences in expression of PCGs between two developmental stages. However, significant variation in levels of different PCGs was observed within each developmental stage.