The complete mitochondrial genome of the conifer needle endophyte, Phialocephala scopiformis DAOMC 229536 confirms evolutionary division within the fungal Phialocephala fortinii s.l. – Acephala appalanata species complex

Abstract

Despite the recent surge in mitochondrial (mt) genome sequencing, Kingdom Fungi remains underrepresented with respect to mtDNA. We describe the mt genome of the conifer needle endophyte, Phialocephala scopiformis DAOMC 229536 (Helotiales, Ascomycota). This strain is of interest to the Canadian forestry industry as it produces the anti-insectan compound rugulosin. Sequence was obtained from whole genome shotgun sequencing. Comparison to the only other published Phialocephala mt genome, Phialocephala subalpina, indicates that the suite of common mt genes - cox1-3, cob, nad1-6 and 4L, atp6, 8 and 9, as well as rrnL and rrnS - has retained an identical order. Nad4L remains one of the most conserved mitochondrial genes within Phialocephala. Members of the closely related Phialocephala fortinii s.l. - Acephala appalanata species complex (PAC) share too much sequence similarity to properly resolve lineages using ITS barcoding alone. Using P. scopiformis sequence as an outgroup, we determined ancestral gene states that help confirm clades within Phialocephala. Our results show: (1) the complete mt genome of P. scopiformis, representing the 10th complete mt genome for the order Helotiales (containing >3800 species), and (2) how large-scale genomic patterns, such as mitochondrial gene order, can be used to confirm lineages within fungal species complexes.

Revealing the high variability on nonconserved core and mobile elements of Austropuccinia psidii and other rust mitochondrial genomes

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