Mitochondrial genomes in the iconic reindeer lichens: Architecture, variation, and synteny across multiple evolutionary scales
- Author:
- Hoffman J.R., Karol K.G., Ohmura Y., Pogoda C.S., Keepers K.G., McMullin R.T. & Lendemer J.C.
- Year:
- 2023
- Journal:
- Mycologia
- Pages:
- 115(2): 187–205
- Url:
- https://doi.org/10.1080/00275514.2022.2157665
Variation in mitochondrial genome composition across intraspecific, interspecific, and higher
taxonomic scales has been little studied in lichen obligate symbioses. Cladonia is one of the
most diverse and ecologically important lichen genera, with over 500 species representing an
array of unique morphologies and chemical profiles. Here, we assess mitochondrial genome
diversity and variation in this flagship genus, with focused sampling of two clades of the
“true” reindeer lichens, Cladonia subgenus Cladina, and additional genomes from nine outgroup
taxa. We describe composition and architecture at the gene and the genome scale,
examining patterns in organellar genome size in larger taxonomic groups in Ascomycota.
Mitochondrial genomes of Cladonia, Pilophorus, and Stereocaulon were consistently larger than
those of Lepraria and contained more introns, suggesting a selective pressure in asexual
morphology in Lepraria driving it toward genomic simplification. Collectively, lichen mitochondrial
genomes were larger than most other fungal life strategies, reaffirming the notion that
coevolutionary streamlining does not correlate to genome size reductions. Genomes from
Cladonia ravenelii and Stereocaulon pileatum exhibited ATP9 duplication, bearing paralogs that
may still be functional. Homing endonuclease genes (HEGs), though scarce in Lepraria, were
diverse and abundant in Cladonia, exhibiting variable evolutionary histories that were sometimes
independent of the mitochondrial evolutionary history. Intraspecific HEG diversity was
also high, with C. rangiferina especially bearing a range of HEGs with one unique to the
species. This study reveals a rich history of events that have transformed mitochondrial
genomes of Cladonia and related genera, allowing future study alongside a wealth of
assembled genomes.
Keywords: Ascomycetes; Cladoniaceae;
fungi; North America;
organelle; transposable
elements.
- Id:
- 35452
- Submitter:
- zpalice
- Post_time:
- Wednesday, 24 May 2023 11:42