Experimental Insights into Horizontal Transfer of Fungal Starship Megatransposons

Starships are a recently discovered class of cargo-carrying fungal megatransposons, whose phylogenetic distribution suggests that they are capable of horizontal transfer between species. In this project, I attempted to experimentally verify horizontal Starship transfer in a laboratory setting. I designed plasmid vectors to induce auxotrophy and insert a hygromycin resistance tag in the Starship of an Aspergillus fumigatus donor strain. I then confronted it with potential acceptor strains under different culturing conditions, intending to trigger horizontal transfer of the Starship element. I also used mycoparasitic Trichoderma as an acceptor strain, to investigate whether the close hyphal contact of mycoparasitic interaction would facilitate horizontal transfer. None of these experiments led to a detectable transfer event, emphasizing that the complexities of Starship transfer are not yet fully understood, and more work is needed to develop a working system for inducing it in laboratory conditions. Additionally, I bioinformatically identified three new putative Starships in Trichoderma virens, forming the first instance of Starships discovery in this genus.