The effect of fertilization on the below-ground diversity and community composition of ectomycorrhizal fungi associated with western hemlock (Tsuga heterophylla)

Cortinarius subsalor and C. tibeticisalor spp. nov., two new species from the section Delibuti from China

Cortinarius subsalor and C. tibeticisalor, belonging to the section Delibuti, are described from China as new to science. Cortinarius subsalor has been found to be associated with Lithocarpus trees in subtropical China and resembling C. salor, but it differs from the later by having slender basidiomata and the narrower basidiospores. Cortinarius tibeticisalor was collected from eastern Tibetan Plateau, associated with Abies. It differs from other species within sect. Delibuti by having olive tinge of mature or dried basidiomata and bigger basidiospores. The molecular data also support C. subsalor and C. tibeticisalor as new species. The phylogenetic analyses and biogeography of sect. Delibuti are discussed and a key to the species of this section currently known in the world is provided.

A phylogenetic overview of the Hydnaceae (Cantharellales, Basidiomycota) with new taxa from China

The family Hydnaceae (Cantharellales, Basidiomycota) is a group of fungi found worldwide which exhibit stichic nuclear division. The group is highly diverse in morphology, ecology, and phylogeny, and includes some edible species which are popular all over the world. Traditionally, Hydnaceae together with Cantharellaceae, Clavulinaceae and Sistotremataceae are four families in the Cantharellales. The four families were combined and redefined as "Hydnaceae", however, a comprehensive phylogeny based on multiple-marker dataset for the entire Hydnaceae sensu stricto is still lacking and the delimitation is also unclear. We inferred Maximum Likelihood and Bayesian phylogenies for the family Hydnaceae from the data of five DNA regions: the large subunit of nuclear ribosomal RNA gene (nLSU), the internal transcribed spacer regions (ITS), the mitochondrial small subunit rDNA gene (mtSSU), the second largest subunit of RNA polymerase II (RPB2) and the translation elongation factor 1-alpha gene (TEF1). We also produced three more phylogenetic trees for Cantharellus based on 5.8S, nLSU, mtSSU, RPB2 and TEF1, Craterellus and Hydnum both based on the combined nLSU and ITS. This study has reproduced the status of Hydnaceae in the order Cantharellales, and phylogenetically confirmed seventeen genera in Hydnaceae. Twenty nine new taxa or synonyms are described, revealed, proposed, or reported, including eight new subgenera (Cantharellus subgenus Magnus, Craterellus subgenus Cariosi, subg. Craterellus, subg. Imperforati, subg. Lamelles, subg. Longibasidiosi, subg. Ovoidei, and Hydnum subgenus Brevispina); seventeen new species (Ca. laevihymeninus, Ca. magnus, Ca. subminor, Cr. badiogriseus, Cr. croceialbus, Cr. macrosporus, Cr. squamatus, H. brevispinum, H. flabellatum, H. flavidocanum, H. longibasidium, H. pallidocroceum, H. pallidomarginatum, H. sphaericum, H. tangerinum, H. tenuistipitum and H. ventricosum); two synonyms (Ca. anzutake and Ca. tuberculosporus as Ca. yunnanensis), and two newly recorded species (H. albomagnum and H. minum). The distinguishing characters of the new species and subgenera as well as their allied taxa are discussed in the notes which follow them. The delimitation and diversity in morphology, ecology, and phylogeny of Hydnaceae is discussed. Notes of seventeen genera which are phylogenetically accepted in Hydnaceae by this study and a key to the genera in Hydnaceae are provided.

Khasa D. Edaphic Selection Pressures as Drivers of Contrasting White Spruce Ectomycorrhizal Fungal Community Structure and Diversity in the Canadian Boreal Forest of Abitibi-Témiscamingue Region

Little is known about edaphic selection pressures as drivers of contrasting white spruce ectomycorrhizal fungal community structure and diversity in the Canadian boreal forest. We hypothesized that community composition differs among the four sites sampled-nursery, mining site, forest edge, and natural forest. Ectomycorrhizal (ECM) fungal community structure and diversity was studied at the four locations with soil fertility gradient through morpho-molecular and phylogenetic analyses in relationships with rhizospheric soil chemical properties. 41 different species were identified. Mining site had a significantly different species composition than the surrounding environments. Soil pH and percentage of roots colonized by ECM fungi increased while soil P, N, Fe, C, K, Mg, Al, Ca, and Na contents declined across the soil fertility gradient: nursery → natural forest → forest edge → mining site. Contrary to the preference of acid soils by ECM fungi, a few ecologically adapted to high pH, poor soil chemical fertility, and low organic matter content colonize white spruce roots on the non-acidogenic mining site, allowing natural regeneration of white spruce seedlings. Other ECM fungi are adapted to high fertigation level of commercial nursery. This study clearly shows the contrasting difference in white spruce ectomycorrhizal fungal community structure and diversity driven by edaphic selection pressures.

The role of phosphorus, magnesium and potassium availability in soil fungal exploration of mineral nutrient sources in Norway spruce forests

We investigated fungal growth and community composition in buried meshbags, amended with apatite, biotite or hornblende, in Norway spruce (Picea abies) forests of varying nutrient status. Norway spruce needles and soil collected from forests overlying serpentinite had low levels of potassium and phosphorus, those from granite had low levels of magnesium, whereas those from amphibolite had comparably high levels of these nutrients. We assayed the fungal colonization of meshbags by measuring ergosterol content and fungal community with 454 sequencing of the internal transcribed spacer region. In addition, we measured fine root density. Fungal biomass was increased by apatite amendment across all plots and particularly on the K- and P-deficient serpentinite plots, whereas hornblende and biotite had no effect on fungal biomass on any plots. Fungal community (total fungal and ectomycorrhizal) composition was affected strongly by sampling location and soil depth, whereas mineral amendments had no effect on community composition. Fine root biomass was significantly correlated with fungal biomass. Ectomycorrhizal communities may respond to increased host-tree phosphorus demand by increased colonization of phosphorus-containing minerals, but this does not appear to translate to a shift in ectomycorrhizal community composition. This growth response to nutrient demand does not appear to exist for potassium or magnesium limitation.

Phylogenetic structure of ectomycorrhizal fungal communities of western hemlock changes with forest age and stand type

On Vancouver Island, British Columbia, fertilization with nitrogen (N) and phosphorus (P) following clearcutting increases growth of western hemlock. To explore whether fertilization also resulted in ectomycorrhizal fungal communities that were more or less similar to neighboring unlogged stands, we sampled roots from western hemlock from three replicate plots from each of five different, well-characterized, forest stand types that differed in site type, and in logging and fertilization history. We harvested four samples of 100 ectomycorrhizal root tips from each plot, a total of 60 samples per stand type. From each sample, we analyzed fungal ribosomal internal transcribed spacers and 28S DNA, sequencing 15-29 clones per sample and 60-116 clones per plot. We detected 147 fungal operational taxonomic units among a total of 1435 sequences. Craterellus tubaeformis was frequently present and resulted in a pattern of phylogenetic overdispersion in the fungal communities. Fungal species composition was strongly correlated with foliar nitrogen concentration. However, other site quality factors were also important because the fertilized regenerating hemlock and mature hemlock-amabilis fir forests had similar foliar nitrogen content but little overlap in fungal species. Compared with unfertilized regenerating forests, fungal communities in N + P-fertilized regenerating forests had significantly more species overlap with old growth forests. However, the fungal communities of all regenerating forest were similar to one another and all differed significantly from older forests. By correlating fungal clades with habitats, this research improves understanding of how forest management can contribute to maintaining diverse ectomycorrhizal fungal communities across a landscape.

Mixotrophy of Platanthera minor, an orchid associated with ectomycorrhiza-forming Ceratobasidiaceae fungi

• We investigated the fungal symbionts and carbon nutrition of a Japanese forest photosynthetic orchid, Platanthera minor, whose ecology suggests a mixotrophic syndrome, that is, a mycorrhizal association with ectomycorrhiza (ECM)-forming fungi and partial exploitation of fungal carbon. • We performed molecular identification of symbionts by PCR amplifications of the fungal ribosomal DNA on hyphal coils extracted from P. minor roots. We tested for a (13)C and (15)N enrichment characteristic of mixotrophic plants. We also tested the ectomycorrhizal abilities of orchid symbionts using a new protocol of direct inoculation of hyphal coils onto roots of Pinus densiflora seedlings. • In phylogenetic analyses, most isolated fungi were close to ECM-forming Ceratobasidiaceae clades previously detected from a few fully heterotrophic orchids or environmental ectomycorrhiza surveys. The direct inoculation of fungal coils of these fungi resulted in ectomycorrhiza formation on P. densiflora seedlings. Stable isotope analyses indicated mixotrophic nutrition of P. minor, with fungal carbon contributing from 50% to 65%. • This is the first evidence of photosynthetic orchids associated with ectomycorrhizal Ceratobasidiaceae taxa, confirming the evolution of mixotrophy in the Orchideae orchid tribe, and of ectomycorrhizal abilities in the Ceratobasidiaceae. Our new ectomycorrhiza formation technique may enhance the study of unculturable orchid mycorrhizal fungi.

Archaeorhizomycetes: unearthing an ancient class of ubiquitous soil fungi

Estimates suggest that only one-tenth of the true fungal diversity has been described. Among numerous fungal lineages known only from environmental DNA sequences, Soil Clone Group 1 is the most ubiquitous. These globally distributed fungi may dominate below-ground fungal communities, but their placement in the fungal tree of life has been uncertain. Here, we report cultures of this group and describe the class, Archaeorhizomycetes, phylogenetically placed within subphylum Taphrinomycotina in the Ascomycota. Archaeorhizomycetes comprises hundreds of cryptically reproducing filamentous species that do not form recognizable mycorrhizal structures and have saprotrophic potential, yet are omnipresent in roots and rhizosphere soil and show ecosystem and host root habitat specificity.

Rapid identification and detection of pine pathogenic fungi associated with mountain pine beetles by padlock probes

Fifteen million hectares of pine forests in western Canada have been attacked by the mountain pine beetle (Dendroctonus ponderosae; MPB), leading to devastating economic losses. Grosmannia clavigera and Leptographium longiclavatum, are two fungi intimately associated with the beetles, and are crucial components of the epidemic. To detect and discriminate these two closely related pathogens, we utilized a method based on ligase-mediated nucleotide discrimination with padlock probe technology, and signal amplification by hyperbranched rolling circle amplification (HRCA). Two padlock probes were designed to target species-specific single nucleotide polymorphisms (SNPs) located at the inter-generic spacer 2 region and large subunit of the rRNA respectively, which allows discrimination between the two species. Thirty-four strains of G. clavigera and twenty-five strains of L. longiclavatum representing a broad geographic origin were tested with this assay. The HRCA results were largely in agreement with the conventional identification based on morphology or DNA-based methods. Both probes can also efficiently distinguish the two MPB-associated fungi from other fungi in the MPB, as well as other related fungi in the order Ophiostomatales. We also tested this diagnostic method for the direct detection of these fungi from the DNA of MPB. A nested PCR approach was used to enrich amplicons for signal detection. The results confirmed the presence of these two fungi in MPB. Thus, the padlock probe assay coupled with HRCA is a rapid, sensitive and reproducible method for the identification and detection of these ophiostomatoid fungi.

Co-invasion by Pinus and its mycorrhizal fungi

*The absence of co-evolved mutualists of plants invading a novel habitat is the logical corollary of the more widely recognized 'enemy escape'. To avoid or overcome the loss of mutualists, plants may co-invade with nonnative mutualists, form novel associations with native mutualists or form associations with native cosmopolitan mutualists, which are native but not novel to the invading plant. *We tested these hypotheses by contrasting the ectomycorrhizal fungal communities associated with invasive Pinus contorta in New Zealand with co-occurring endemic Nothofagus solandri var. cliffortioides. *Fungal communities on Pinus were species poor (14 ectomycorrhizal species) and dominated by nonnative (93%) and cosmopolitan fungi (7%). Nothofagus had a species-rich (98 species) fungal community dominated by native Cortinarius and two cosmopolitan fungi. *These results support co-invasion by mutualists rather than novel associations as an important mechanism by which plants avoid or overcome the loss of mutualists, consistent with invasional meltdown.