New 1,3-benzodioxin-4-ones from Synnemapestaloides ericacearum sp. nov., a biosynthetic link to remarkable compounds within the Xylariales

• Published in: PloS one 2018-06, Vol.13 (6), p.e0198321
• Main Authors: Tanney, Joey B, Renaud, Justin B, Miller, J David, McMullin, David R
• Format: Article
• Language: English
• Subjects: Anti-Infective Agents - chemistry; Anti-Infective Agents - isolation & purification; Anti-Infective Agents - pharmacology; Antibiotics; Antifungal activity; Antifungal agents; Antimicrobial activity; Bacteria - drug effects; Biodiversity; Biological Products - chemistry; Biological Products - isolation & purification; Biological Products - pharmacology; Biology; Biology and Life Sciences; Biosynthesis; Chemical properties; Chemistry; Coastal morphology; Computer and Information Sciences; Dioxoles - chemistry; Dioxoles - isolation & purification; Dioxoles - pharmacology; Discovery and exploration; Endophytes; Ericaceae; Ericaceae - microbiology; Filtrate; Foliage; Forests; Fungi; Fungicides; Health aspects; Host preferences; Kalmia latifolia; Leaves; Ledum - microbiology; Medicine and Health Sciences; Metabolites; Molecular Structure; Morphology; Mycotoxins; Natural products; New Brunswick; New species; Pests; Phylogenetics; Phylogeny; Physical characteristics; Plant Leaves - microbiology; Plant tissues; R&D; Research & development; Research and analysis methods; Rhododendron; Ribosomal DNA; Sporocarps; Tea; Trichoderma; Understory; Xylariales - chemistry; Xylariales - classification; Xylariales - isolation & purification; Xylariomycetidae
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0198321

Surveys of foliar endophytes from the Acadian forest region over the past three decades have identified numerous phylogenetically diverse fungi producing natural products toxic to forest pests and diseases. The life histories of some conifer endophytes can be restricted to plant foliage or may include saprotrophic phases on other plants tissues or even alternate hosts. Considering the potentially broad host preferences of conifer endophytes we explored fungi isolated from understory species and their metabolites as part of an ongoing investigation of fungal biodiversity from the Acadian forest. We report a hitherto unidentified Xylariomycetidae species isolated from symptomatic Labrador tea (Rhododendron groenlandicum) leaves and mountain laurel (Kalmia latifolia) collected in coastal southern New Brunswick, Canada. Morphological and phylogenetic evidence demonstrated the unknown species was a novel Synnemapestaloides (Sporocadaceae) species, described here as Syn. ericacearum. A preliminary screening assay indicated that the culture filtrate extract of the new species was potently antifungal towards the biotrophic pathogen Microbotryum violaceum, warranting an investigation of its natural products. Two natural products possessing a rare 1,3-benzodioxin-4-one scaffold, synnemadoxins A-B (1-2), and their postulated precursor, synnemadiacid A (3), were characterized as new structures and assessed for antimicrobial activity. All isolated compounds elicited in vitro inhibitory antifungal activity towards M. violaceum at 2.3 μg mL-1 and moderate antibiotic activity. Further, the characterization of synnemadoxins A-B provided a perspective on the biosynthesis of some related 1,3-benzodioxin-4-ones produced by other fungi within the Xylariales.