Molecular and morphological characterization of Dothiorella species associated with dieback of Ostrya carpinifolia in Slovenia and Italy

Abstract

Isolates that resemble Dothiorella (Botryosphaeriaceae, Ascomycota) species were isolated from dead twigs, asymptomatic and necrotized bark of European hop hornbeam (Ostrya carpinifolia Scop.), Eurasian smoke tree (Cotinus coggygria Scop.) and common juniper (Juniperus communis L.) growing in western Slovenia and northern Italy. They were identified based on anamorph morphology and phylogenetic analyses of the ITS rDNA and EF-1α sequences, and previously designated as Dothiorella sp. A, B and C. This study has clarified the identity of these species by comparing them with other Dothiorella species known from culture based on gene sequence data, as well as morphological characters of the anamorphs. The phylogenetic results revealed three species, Dothiorella iberica, Dothiorella parva, and a Dothiorella sp. Isolates identified in the phylogenetic analyses as D. parva differed from the original description of this species and are thus described here based on the anamorph morphology. Isolates of D. parva were identified from O. carpinifolia in western Slovenia and northern Italy, and C. coggygria in western Slovenia, and coexist with Dothiorella sp. on O. carpinifolia in northern Italy. Dothiorella iberica was identified on J. communis in western Slovenia, thus expanding the geographic range of this species. This is the first record of D. parva from these hosts and countries. Our results indicate that these Dothiorella species occur widely across the Mediterranean region, and on a variety of hosts.