Molecular reassessment of diaporthalean fungi associated with strawberry, including the leaf blight fungus, Paraphomopsis obscurans gen. et comb. nov. (Melanconiellaceae)
2022
Udayanga, Dhanushka | Miriyagalla, Shaneya D. | Manamgoda, Dimuthu S. | Lewers, Kimberly S. | Gardiennet, Alain | Castlebury, Lisa A.
Phytopathogenic fungi in the order Diaporthales (Sordariomycetes) cause diseases on numerous economically important crops worldwide. In this study, we reassessed the diaporthalean species associated with prominent diseases of strawberry, namely leaf blight, leaf blotch, root rot and petiole blight, based on molecular data and morphological characters using fresh and herbarium collections. Combined analyses of four nuclear loci, 28S ribosomal DNA/large subunit rDNA (LSU), ribosomal internal transcribed spacers 1 and 2 with 5.8S ribosomal DNA (ITS), and partial sequences of second largest subunit of RNA polymerase II (RPB2) and translation elongation factor 1-a (TEF1), were used to reconstruct a phylogeny for these pathogens. Results confirmed that the leaf blight pathogen formerly known as Phomopsis obscurans belongs in the family Melanconiellaceae and is not congeneric with Diaporthe (syn. Phomopsis). A new genus Paraphomopsis is introduced herein with a new combination, Paraphomopsis obscurans, to accommodate the leaf blight fungus. Gnomoniopsis fragariae comb. nov. (Gnomoniaceae), is introduced to accommodate Gnomoniopsis fructicola, the cause of leaf blotch of strawberry. Fresh collections and new molecular data were incorporated for the recently typified species, Paragnomia fragariae (Sydowiellace), which causes petiole blight and root rot of Fragaria spp. and is distinct from the above taxa. An updated multi-locus phylogeny for the Diaporthales is provided to place and distinguish the leaf blight and leaf blotch pathogen, as well as the species associated with petiole blight and root rot of strawberry.
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