Epipactis helleborine is an orchid species that has been introduced to North America and continues to expand its range. Numerous studies have investigated the mycorrhizal specificity of these orchids in their native range and found broad associations with Ascomycota, particularly Wilcoxina. Similar studies in North America are rare. We assessed the fungal diversity associated with populations of E. helleborine, and the surrounding soil, in mixed habitats on Vancouver Island (Canada) to make comparisons with findings from the species native range. After collecting 45 rhizomes and 36 soil samples, we amplified the nuclear ribosomal internal transcribed spacer (ITS2) region to assess alpha and beta diversity. BLAST searches were conducted, and phylogenetic reconstructions of high-matching fungal sequences from other E. helleborine studies were created. We demonstrate that E. helleborine populations continue to associate with a diverse group of Ascomycota fungi, particularly Wilcoxina spp. as they continue to expand their range northward in western North America. However, we also detected a novel association among E. helleborine rhizomes and Rhexocercosporidium, a genus containing known saprophytes and plant pathogens. Our results indicate that this orchid can pair with an extensive range of fungal partners, likely by taking advantage of varying degrees of phylogenetic niche conservatism among different fungal groups, which could have wide-reaching implications in terms of further geographic expansion and introductions to new continents.
Red leaf blotch, caused by Coniothyrium glycines, is a major leaf spot disease of soybean in Africa. Because of its unique morphological characteristics, C. glycines has been placed in numerous genera since its description in 1957, and recent phylogenetic evidence has suggested that its current placement within Coniothyrium is incorrect. To provide nomenclatural stability, we reevaluated its evolutionary history and taxonomy using a phylogenomic approach. We produced draft genomes for 13 close relatives of C. glycines and generated a consensus tree from 4643 BUSCO genes in these species and related Dothideomycetes. We show that Coniothyrium is not monophyletic and C. glycines is closely related to Aristastoma oeconomicum, a once prevalent leaf spot pathogen of cowpea in the eastern United States. Similarities in morphology and disease symptomology, along with genome distance estimations and a phylogeny based on internal transcribed spacer (ITS) and partial nuclear 28S rDNA (D1-D2) data, support the transfer of C. glycines and another species, Coniothyrium dolichi, to Aristastoma. The inclusion of this species in Aristastoma expands the morphological concept of this genus to include species that produce sclerotia and have aseptate conidia. The improved systematics and genomic resources generated with this study will advance the development of diagnostics and detection assays of this high-consequence plant pathogen.
Several species of mushroom-forming fungi have been reported to trap and consume nematodes. Nematophagy is hypothesized to have evolved as a mechanism for supplementing nitrogen, analogous to carnivorous plants. In this study, we systematically reviewed all the putative nematode-trapping saprotrophic Agaricales and documented their behavior in the presence of nematodes. Hohenbuehelia mastrucata, Pleurotus citrinopileatus, and P. djamor all trapped and consumed nematodes, as reported previously. In contrast, we found that Stropharia rugosoannulata and Coprinus comatus produce structures that have been suggested to function in nematode trapping, but these fungi neither trap nor consume the nematodes. It is possible that the structures interpreted to function in nematode trapping in S. rugosoannulata and C. comatus act as defensive mechanisms against fungivory.
Six new species of Inocybaceae from North America are described as new. Most are common and widespread throughout eastern North America. Phylogenetic analyses of nuc rDNA ITS1-5.8S-ITS2 (ITS), harnessing numerous community science records, together with nuc 28S rDNA support the phylogenetic distinctiveness of each species with strong support values. Sequences of additional genetic loci, including RNA polymerase II largest subunit (rpb1) and second largest subunit (rpb2), were also produced to supplement the descriptions and strengthen future phylogenetic studies. Of these new taxa, three are described in Inocybe: I. albofusca, a smooth-spored species in the Flocculosa clade; I. communis, a nodulose-spored species in the Xanthomelas clade; and I. lincoffii, a nodulose-spored species in I. subsect. Napipedinae. Inosperma aureiavis is a member of the Maculatum clade, whereas Pseudosperma aurivetum is a member of the Umbrinellum clade. Mallocybe diabolica is a narrow-range endemic known only from southeastern Arizona and Mexico and is allied with the Heimii clade. Complete descriptions and illustrations are presented for each species.
