Toniniopsis dissimilis strain:M-0355157 Genome sequencing

Lichens have developed numerous adaptations to optimize their survival in various environmental conditions, largely by producing secondary compounds by the fungal partner. They often have antibiotic properties and are involved in protection against intensive U.V. radiation, pathogens, and herbivores. To contribute to the knowledge of the arsenal of secondary compounds in a crustose lichen species, we sequenced and assembled the genome of Toniniopsis dissimilis, an indicator of old-growth forests, using Oxford Nanopore Technologies (ONT, Oxford, UK) long reads. Our analyses focused on biosynthetic gene clusters (BGCs) and specifically on Type I Polyketide Genes (T1PKS) genes involved in the biosynthesis of polyketides. We used the compar-ative genomic approach to compare the genome of T. dissimilis with six other members of the family Ramalinaceae and twenty additional lichen genomes from the database. With only six T1PKS genes, a comparatively low number of those biosynthetic genes are present in the T. dissimilis genome, and from those, two-thirds are putatively involved in melanin biosynthesis. The comparative analyses showed at least three potential pathways of melanin biosynthesis in T. dissimilis, namely via the formation of 1,3,6,8-tetrahydroxynaphthalene, naphthopyrone, or YWA1 putative precursors, which highlights its importance in T. dissimilis. In addition, we report the oc-currence of genes encoding ribosomally synthesized and post-translationally modified peptides (RiPPs) in lichens, with their highest number in T. dissimilis compared to other Ramalinaceae ge-nomes. So far, no function has been assigned to RiPP-like proteins in lichens, which leaves potential for future research on this topic.