Abstract
Hortaea werneckii, an extreme halotolerant black yeast in the order of Capnodiales, was recently isolated from different stations and depths in the Mediterranean Sea, where it was shown to be the dominant fungal species. In order to explore the genome characteristics of these Mediterranean isolates, we carried out a de-novo sequencing of the genome of one strain isolated at a depth of 3400 m (MC873) and a re-sequencing of one strain taken from a depth of 2500 m (MC848), whose genome was previously sequenced but was highly fragmented. A comparative phylogenomic analysis with other published H. werneckii genomes was also carried out to investigate the evolution of the strains from the deep sea in this environment. A high level of genome completeness was obtained for both genomes, for which genome duplication and an extensive level of heterozygosity (~4.6%) were observed, supporting the recent hypothesis that a genome duplication caused by intraspecific hybridization occurred in most H. werneckii strains. Phylogenetic analyses showed environmental and/or geographical specificity, suggesting a possible evolutionary adaptation of marine H. werneckii strains to the deep sea environment. We release high-quality genome assemblies from marine H. werneckii strains, which provides additional data for further genomics analysis, including niche adaptation, fitness and evolution studies.
Highlights
Hortaea werneckii belongs to the so-called black yeast, a polyphyletic group of pleomorphic and melanised fungi that present in many cases a polyextremotolerant lifestyle [1,2]
H. werneckii is assigned to the division of Ascomycota in the family Teratosphaeriaceae (Pezizomycotina, Dothideomycetes, Capnodiales) and the species was previously classified as Exophiala werneckii, Cladosporium werneckii or Phaeoannellomyces werneckii [9], until the genus Hortaea was established [10]
Automatic functional annotation of predicted proteins was performed using PANNZER2 program [41] and resulting proteomes were compared by OrthoFinder (v.2.3.11)
Summary
Hortaea werneckii belongs to the so-called black yeast, a polyphyletic group of pleomorphic and melanised fungi that present in many cases a polyextremotolerant lifestyle [1,2]. Up to date, this species was mainly studied for its remarkable halo-tolerance, being the only known fungus able to grow in a wide range of salinity, from 0 M NaCl to saturation at 5.1 M NaCl [3,4]. The identification at species level is complicated by the fact that some housekeeping genes commonly used for taxonomic purposes, such as β-tubulin, Life 2020, 10, 229; doi:10.3390/life10100229 www.mdpi.com/journal/life
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