An Antarctic lichen isolate (Cladonia borealis) genome reveals potential adaptation to extreme environments

Abstract

Cladonia borealis is a lichen that inhabits Antarctica’s harsh environment. We sequenced the whole genome of a C. borealis culture isolated from a specimen collected in Antarctica using long-read sequencing technology to identify specific genetic elements related to its potential environmental adaptation. The final genome assembly produced 48 scaffolds, the longest being 2.2 Mbp, a 1.6 Mbp N50 contig length, and a 36 Mbp total length. A total of 10,749 protein-coding genes were annotated, containing 33 biosynthetic gene clusters and 102 carbohydrate-active enzymes. A comparative genomics analysis was conducted on six Cladonia species, and the genome of C. borealis exhibited 45 expanded and 50 contracted gene families. We identified that C. borealis has more Copia transposable elements and expanded transporters (ABC transporters and magnesium transporters) compared to other Cladonia species. Our results suggest that these differences contribute to C. borealis’ remarkable adaptability in the Antarctic environment. This study also provides a useful resource for the genomic analysis of lichens and genetic insights into the survival of species isolated from Antarctica.

Discovery and heterologous expression of functional 4-O-dimethylallyl-L-tyrosine synthases from lichen-forming fungi

“…Lichens are relatively underexplored because of their complex biology, as well as the technical challenges around cultivation in laboratory settings [6]. Thanks to advancements in DNA sequencing technologies and bioinformatics, it has recently become easier to obtain high-quality genome sequences from lichen-forming fungi and thus gauge their biosynthetic capabilities [7][8][9]. A major challenge, however, remains the heterologous expression of genes originating from these organisms, thus hampering the linking of metabolites to biosynthetic genes [10,11].…”