Cytospora paraplurivora sp. nov. isolated from orchards with fruit tree decline syndrome in Ontario, Canada

Abstract

A new species ofCytosporawas isolated from cankered wood ofPrunusspp. during a survey of orchards exhibiting symptoms of fruit tree decline syndrome in southern Ontario, Canada. We found isolates that are morphologically similar to species in theCytosporaceaefamily, which is characterized by single or labyrinthine locules, filamentous conidiophores or clavate to elongate obovoid asci and allantoid, hyaline conidia. Multi-gene phylogenetic analysis of ITS, LSU,actandtef1- αshowed that the isolates form a distinct clade, sister toCytospora plurivora. Morphologically, our isolates showed differences in the length of conidia and culture characteristics compared toC.plurivora, suggesting the establishment of a new species. The species is described asCytospora paraplurivorasp. nov. and placed in the familyCytosporaceaeofDiaporthales. Additionally, we sequenced, assembled and characterized the genome of the representative isolate for this new species. The phylogenomic analysis confirms the species order and family level classification.C.paraplurivorasp. nov. has the potential to severely affect stone fruits production, causing cankers and dieback in stressed trees, and eventually leads to tree decline. Pathogenicity tests show that the species is pathogenic toPrunus persica var.persica.