Genome sequence of Pseudopithomyces chartarum, causal agent of facial eczema (pithomycotoxicosis) in ruminants, and identification of the putative sporidesmin toxin gene cluster

Abstract

<jats:title>Abstract</jats:title><jats:p>Facial eczema (FE) in grazing ruminants is a debilitating liver syndrome induced by ingestion of sporidesmin, a toxin belonging to the epipolythiodioxopiperazine class of compounds. Sporidesmin is produced in spores of the fungus <jats:italic>Pseudopithomyces chartarum</jats:italic>, a microbe which colonises leaf litter in pastures. New Zealand has a high occurrence of FE in comparison to other countries as animals are fed predominantly on ryegrass, a species that supports high levels of <jats:italic>Pse. chartarum</jats:italic> spores. The climate is also particularly conducive for <jats:italic>Pse. chartarum</jats:italic> growth. Here, we present the genome of <jats:italic>Pse. chartarum</jats:italic> and identify the putative sporidesmin gene cluster. The <jats:italic>Pse. chartarum</jats:italic> genome was sequenced using single molecule real-time sequencing (PacBio) and gene models identified. Loci containing genes with homology to the aspirochlorine, sirodesmin PL and gliotoxin cluster genes of <jats:italic>Aspergillus oryzae, Leptosphaeria maculans</jats:italic> and <jats:italic>Aspergillus fumigatus</jats:italic>, respectively, were identified by tBLASTn. We identified and annotated an epipolythiodioxopiperazine cluster at a single locus with all the functionality required to synthesise sporidesmin.</jats:p><jats:sec><jats:title>Highlights</jats:title><jats:list list-type="bullet"><jats:list-item><jats:p>The whole genome of <jats:italic>Pseudopithomyces chartarum</jats:italic> has been sequenced and assembled.</jats:p></jats:list-item><jats:list-item><jats:p>The genome is 39.13 Mb, 99% complete, and contains 11,711 protein coding genes.</jats:p></jats:list-item><jats:list-item><jats:p>A putative sporidesmin A toxin (cause of facial eczema) gene cluster is described.</jats:p></jats:list-item><jats:list-item><jats:p>The genomes of <jats:italic>Pse. chartarum</jats:italic> and the <jats:italic>Leptosphaerulina chartarum</jats:italic> teleomorph differ.</jats:p></jats:list-item><jats:list-item><jats:p>Comparative genomics is required to further resolve the <jats:italic>Pseudopithomyces</jats:italic> clade.</jats:p></jats:list-item></jats:list></jats:sec>