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 near-gapless 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.