Coniochaeta endophytica sp. nov., a foliar endophyte associated with healthy photosynthetic tissue of Platycladus orientalis (Cupressaceae)

Abstract

The ecologically diverse genus Coniochaeta (Coniochaetaceae, Ascomycota) contains numerous endophytic strains that occur in healthy leaves and lichen thalli in temperate and boreal North America. These endophytes frequently represent undescribed species. Here we examine two endophytic isolates of Coniochaeta from healthy photosynthetic tissue of Platycladus orientalis (Cupressaceae), a conifer cultivated for horticultural use in Arizona, USA. On the basis of morphology, in vitro assays, phylogenetic analyses of two loci, and analyses of whole genome data, we designate these endophytes as a novel species, Coniochaeta endophytica sp. nov. Strains of C. endophytica are closely related to an isolate from a native lichen in North Carolina, which we also characterize here. We compare C. endophytica with two known species that appear to be close relatives: C. prunicola, associated with wood necrosis in stonefruit trees in South Africa, and C. cephalothecoides, isolated from soil in Asia. The new species is distinct in phylogenetic, in vitro, and whole-genome analyses from C. prunicola, and differs slightly in conidiophore morphology from that species. Although available sequence data for C. cephalothecoides are of uncertain relation to the type specimen for that species, our results support the distinctiveness of C. endophytica on the basis of morphology, perithecial formation, and phylogenetic analyses. We discuss the challenge of identifying new species in the context of fungal ecology surveys, such as those for endophytes, which often rely only on a single locus and can misidentify taxa based on their closest matches in public databases or simple comparisons of barcode sequences alone.

Secondary metabolism drives ecological breadth in the Xylariaceae

“…Inclusion of previously unstudied endophytic taxa markedly increased the known phylogenetic diversity of the family 7 (Supplementary Fig. 1), highlighting the importance of including unnamed endophytes (which are typically sterile mycelium in culture which precludes morphological characterization and formal naming; but see 115 ) in phylogenetic studies.…”

Taxonomic Re-Examination of Nine Rosellinia Types (Ascomycota, Xylariales) Stored in the Saccardo Mycological Collection

“…The molecular analysis of the holotype confirms the taxonomic re-classification proposed by Popushoi [ 60 ]. Coniochaeta endophytica was described only from its asexual stage [ 39 ]. Coniochaeta prunicola has ascospores similar to Rosellinia ambigua (9.2 ± 0.6 × 6.7 ± 0.6 μm) but it differs in the dimension of ascomata (200–250 μm diam), the presence of a long neck above the perithecia and shorter asci (av.…”

Two new endophytic species enrich the Coniochaeta endophytica / C. prunicola clade: Coniochaeta lutea sp. nov. and C. palaoa sp. nov.

“…Fungal endophytes occur in healthy tissues of plants worldwide (Rodriguez et al 2009). In contrast to fungi that readily produce visible structures on host material or substrates, the diverse endophytes that occur within symptomless tissues of plants and lichens have only recently begun to receive more active attention from systematists (see Bussaban et al 2003;Rojas et al 2008Rojas et al , 2010Gazis et al 2011Gazis et al , 2012Bills et al 2013;Chen et al 2015;Torres-Cruz et al 2017;Harrington et al 2019). A relative lack of studies prior to the past three decades means that endophytes are under-represented in culture collections and may be overlooked in evolutionary or taxonomic treatments, even if they are represented in GenBank with barcode sequences.…”

“…A relative lack of studies prior to the past three decades means that endophytes are under-represented in culture collections and may be overlooked in evolutionary or taxonomic treatments, even if they are represented in GenBank with barcode sequences. Moreover, the prevalence of saprotrophic and pathogenic fungi in collections and databases often leads to casual assignment of their species names to newly discovered endophytes, even though careful exploration can demonstrate the uniqueness and often novelty of the endophytic taxa (Harrington et al 2019). Including endophytes in phylogenetic and taxonomic studies provides insight with regard to the identification of endophytes while informing the diversity, relationships, and ecological traits ascribed to previously described taxa (see U'Ren et al 2016;Carbone et al 2016;Torres-Cruz et al 2017;Harrington et al 2019).…”

“…Temperate and boreal plants and lichens frequently harbor endophytes in the genus Coniochaeta (Coniochaetaceae; Coniochaetales; Sordariomycetes, Ascomycota). Diverse strains can be isolated readily from healthy, surface-sterilized tissues on standard media such as malt extract agar (MEA) (e.g., Arnold & Hoffman 2008;U'Ren et al 2012;del Olmo Ruiz 2012;Huang et al 2016;Chen 2017;Harrington et al 2019;U'Ren et al 2019;Oita et al 2021). As described in Harrington et al (2019), Coniochaeta is a diverse genus with species that inhabit a wide range of substrates, including butter, dung, wood, soil, uranium mine wastewater, lichens, and healthy, diseased, or senescent tissues of mosses, ferns, conifers, and angiosperms (see also Weber 2002;García et al 2006;del Olmo Ruiz 2012;Rafa et al 2012;Vázquez-Campos et al 2014;Xie et al 2015;Chen 2017;U'Ren et al 2019).…”