Dijkstra, J.; van Westerhoven, A. C.; Li, Y.; Aguilera-Galvez, C.; Nakasato-Tagami, G.; Shi-Kunne, X.; Etalo, D. W.; Kema, G. H. J.

Transposable elements can significantly influence the genome dynamics of clonal fungal plant pathogens. Tropical Race 4 (TR4) is a clonal lineage within the Fusarium oxysporum species complex that poses a substantial threat to global banana production. However, how transposable elements shape TR4s genome and adaptation remains underexplored. We investigated the activity and impact of FoHeli1, a Helitron transposable element in the TR4 lineage, focusing on a Mozambican TR4 strain (M1) through a combination of genome analyses, metabolite profiling, and infection assays. FoHeli1 activity has been very recent within the TR4 lineage and is likely still ongoing. This has resulted in large structural variations in M1, including the loss of the conserved biosynthetic gene cluster required for the production of fusaric acid. We demonstrate that this deletion abolishes fusaric acid production and alters secondary metabolite profiles, but does not affect pathogenicity. Our results emphasize the significance of transposable elements, particularly FoHeli1, in reshaping the genetic and metabolic landscape of TR4 and challenge existing assumptions about the role of fusaric acid in pathogenicity.