The genome of the saprophytic fungus Verticillium tricorpus reveals a complex effector repertoire resembling that of its pathogenic relatives

Vascular wilts caused by Verticillium spp. are destructive plant diseases affecting hundreds of hosts. Only a few Verticillium spp. are causal agents of vascular wilt diseases, of which V. dahliae is the most notorious pathogen, and several V. dahliae genomes are available. In contrast, V. tricorpus is mainly known as a saprophyte and causal agent of opportunistic infections. Based on a hybrid approach that combines second and third generation sequencing, a neargapless V. tricorpus genome assembly was obtained. With comparative genomics, we sought to identify genomic features in V. dahliae that confer the ability to cause vascular wilt disease. Unexpectedly, both species encode similar effector repertoires and share a genomic structure with genes encoding secreted proteins clustered in genomic islands. Intriguingly, V. tricorpus contains significantly fewer repetitive elements and an extended spectrum of secreted carbohydrate- active enzymes when compared with V. dahliae. In conclusion, we highlight the technical advances of a hybrid sequencing and assembly approach and show that the saprophyte V. tricorpus shares many hallmark features with the pathogen V. dahliae.