Mobile Eukaryotic Chromosomes in Fungal Pathogens

forthcoming

Horizontal gene transfer (HGT) has significantly shaped the evolution and biology of prokaryotes. In eukaryotes, however, the dynamics, mechanisms and consequences of HGT are less well understood, mostly due to its comparatively low frequency and especially the lack of experimental model systems. Recently, I described a model system for studying eukaryotic HGT, consisting of entomopathogenic fungi of the Metarhizium genus. In this taxon, HGT occurs frequently for entire accessory chromosomes. This massive transfer of genetic material is highly specific, always involving the same chromosome, and is likely regulated by the chromosome itself. Using this unique model system, the MobiChrom project addresses key knowledge gaps of HGT in general and horizontal chromosome transfer specifically: What are the evolutionary dynamics of horizontal chromosome transfer? What are the consequences for the recipient fungus's interaction with the insect host? And what are the mechanisms mediating this specific horizontal transfer? First, I will evaluate the distribution of accessory chromosomes across five co-existing Metarhizium species to understand their transfer frequencies and the involved evolutionary dynamics, while identifying candidate genes involved in HGT or host interactions. Next, I will examine how these acquired accessory chromosomes influence the recipient fungus's interaction with the host, functionally analysing how genes on these mobile chromosomes affect pathogenicity. Finally, I will investigate the genetic mechanisms underlying horizontal transfer, identifying the signals responsible for the specific transfer of the mobile chromosome and the genes that regulate this process. Through these complementary study approaches, the MobiChrom project will advance our understanding of the impact of HGT on the biology of organisms and yield fundamental knowledge on the processes, dynamics and functional relevance of the HGT of entire chromosomes in microbial eukaryotes.