Historical genomics reveals the evolutionary mechanisms behind multiple outbreaks of the host-specific coffee wilt pathogen Fusarium xylarioides

Abstract

1Nearly 50% of crop yields are lost to pests and disease, with plants and pathogens locked in an amplified co-evolutionary process of disease outbreaks. Coffee wilt disease, caused by Fusarium xylarioides, decimated coffee production in west and central Africa following an initial 1920s outbreak. After successful management, it later re-emerged reaching two separate epidemics by the 2000s on arabica coffee in Ethiopia and robusta coffee in east and central Africa. Here, we use genome sequencing of six historical culture collection strains spanning 70 years to identify the evolutionary processes behind these repeated outbreaks. The robusta population arose from the initial outbreak, whilst the arabica population is divergent and emerged independently. The two populations evolved similar pathologies by separately acquiring different effector genes horizontally via transposable elements from other Fusarium taxa, including F. oxysporum. Thus, historical genomics can help reveal mechanisms that allow fungal pathogens to keep pace with humanitys efforts to resist them.