Tangerine, a Starship element in the genome of Xanthoria is a representative of a new Starship family unique to lichens

Our paper on Tangerine the lichen Starship is out in PNAS! See below the summary of this study 👇

Discovery of giant transposons Starships challenged what we thought we knew about fungal genomes. But what about Starships in lichen fungi? In this paper, we present the Tangerine element from Xanthoria parietina. Tangerine has all hallmark features of a Starship: 100 kb in length, the captain gene responsible for transposition, as well as accessory genes and ‘cargo’.

Tangerine’s captain didn’t fit into any existing family of Starship captains, but in the tree it grouped together with several genes from other lichen fungi. After expanding our analyses to many more genomes, we were able to describe the clade as the new family, the Tangerine-family, unique to Lecanoromycetes.

Coolest part for me is the tantalizing possibility that Tangerine might have mediated horizontal gene transfer (HGT) between different fungi present within a lichen thallus. Two genes from Tangerine appear to have been horizontally transferred from Chaetothyriales, a group of black fungi. Some Chaetothyriales are stably associated with certain lichens, and our earlier evidence suggest that they can be present in Xanthoria as well. We found other potential HGT events linked to Starships too by juxtaposing phylogenetic tree of the captains with the species phylogeny.

Our little Tangerine is undoubtedly not the only Starship present in lichens! Hopefully we will soon know more about their diversity and what kind of role they play in the evolution of lichen fungi.