Researchers found that a disease-causing gene called ToxA, which helps fungal pathogens infect wheat crops, travels between different fungal species using molecular ‘cargo ships’ called Starship transposons. By sequencing multiple fungal isolates, scientists discovered that ToxA rides within a larger mobile genetic element called Sanctuary that can move around within fungal genomes and between species. This discovery helps explain how wheat pathogens become more dangerous over time through horizontal gene transfer.