Abstract
The genusHelianthusis a diverse taxonomic group with approximately 50 species. Most sunflower genomic investigations are devoted to economically valuable species, e.g.,H. annuus, while otherHelianthusspecies, especially perennial, are predominantly a blind spot. In the current study, we have assembled the complete mitogenomes of two perennial species:H. grosseserratus(273,543 bp) andH. strumosus(281,055 bp). We analyzed their sequences and gene profiles in comparison to the available complete mitogenomes ofH. annuus.Except forsdh4andtrnA-UGC, both perennial sunflower species had the same gene content and almost identical protein-coding sequences when compared with each other and with annual sunflowers (H. annuus). Common mitochondrial open reading frames (ORFs) (orf117,orf139, andorf334) in sunflowers and unique ORFs forH. grosseserratus(orf633) andH. strumosus(orf126,orf184,orf207) were identified. The maintenance of plastid-derived coding sequences in the mitogenomes of both annual and perennial sunflowers and the low frequency of nonsynonymous mutations point at an extremely low variability of mitochondrial DNA (mtDNA) coding sequences in theHelianthusgenus.