The species of Scleroderma from Argentina, including a new species from the Nothofagus forest

Thinning Partially Mitigates the Impact of Atlantic Forest Replacement by Pine Monocultures on the Soil Microbiome

Forest replacement by exotic plantations drive important changes at the level of the overstory, understory and forest floor. In the Atlantic Forest of northern Argentina, large areas have been replaced by loblolly pine (Pinus taeda L.) monocultures. Plant and litter transformation, together with harvesting operations, change microclimatic conditions and edaphic properties. Management practices such as thinning promote the development of native understory vegetation and could counterbalance negative effects of forest replacement on soil. Here, the effects of pine plantations and thinning on physical, chemical and microbiological soil properties were assessed. Bacterial, archaeal, and fungal community structure were analyzed using a metabarcoding approach targeting ribosomal markers. Forest replacement and, to a lesser extent, thinning practices in the pine plantations induced significant changes in soil physico-chemical properties and associated shifts in bacterial and fungal communities. Most measured physical and chemical properties were altered due to forest replacement, but a few of these properties reached values similar to natural forests under the thinning operation. Fungal alpha diversity decreased in pine plantations, whereas bacterial alpha diversity tended to increase but with little statistical support. Shifts in community composition were observed for both fungal and bacterial domains, and were mostly related to changes in plant understory composition, soil carbon, organic matter, water content, pH and bulk density. Among several other changes, highly abundant phyla such as Proteobacteria (driven by many genera) and Mortierellomycota (mainly driven by Mortierella) decreased in relative abundance in the plantations, whereas Acidobacteria (mainly driven by Acidothermus and Candidatus Koribacter) and Basidiomycota (mainly driven by the ectomycorrhiza Russula) showed the opposite response. Taken together, these results provide insights into the effects of forest replacement on belowground properties and elucidate the potentially beneficial effect of thinning practices in intensive plantation systems through promoting the understory development. Although thinning did not entirely counterbalance the effects of forest replacement on physical, chemical and biological soil properties, the strategy helped mitigating the effects and might promote resilience of these properties by the end of the rotation cycle, if subsequent management practices compatible with the development of a native understory vegetation are applied.

Longistriata flava (Boletaceae, Basidiomycota) - a new monotypic sequestrate genus and species from Brazilian Atlantic Forest

A new monotypic sequestrate genus, Longistriata is described based on collections from the Neotropical forest of Atlantic forest in Paraíba, Northeast Brazil – an area known for its high degree of endemism. The striking features of this new fungus are the hypogeous habit, the vivid yellow peridium in mature basidiomes, broadly ellipsoid basidiospores with a distinct wall that is ornamented with longitudinal striations and lageniform cystidia with rounded apices. Phylogenetic analysis, based on LSU and tef-1α regions, showed that the type species, Longistriataflava, is phylogenetically sister to the monotypic sequestrate African genus Mackintoshia in Boletaceae. Together these two species formed the earliest diverging lineage in the subfamily Zangioideae. Longistriataflava is found in nutrient-poor white sand habitats where plants in the genera Coccoloba (Polygonaceae) and Guapira (Nyctaginaceae) are the only potential ectomycorrhizal host symbionts.

Notes, outline and divergence times of Basidiomycota

The Basidiomycota constitutes a major phylum of the kingdom Fungi and is second in species numbers to the Ascomycota. The present work provides an overview of all validly published, currently used basidiomycete genera to date in a single document. An outline of all genera of Basidiomycota is provided, which includes 1928 currently used genera names, with 1263 synonyms, which are distributed in 241 families, 68 orders, 18 classes and four subphyla. We provide brief notes for each accepted genus including information on classification, number of accepted species, type species, life mode, habitat, distribution, and sequence information. Furthermore, three phylogenetic analyses with combined LSU, SSU, 5.8s, rpb1, rpb2, and ef1 datasets for the subphyla Agaricomycotina, Pucciniomycotina and Ustilaginomycotina are conducted, respectively. Divergence time estimates are provided to the family level with 632 species from 62 orders, 168 families and 605 genera. Our study indicates that the divergence times of the subphyla in Basidiomycota are 406–430 Mya, classes are 211–383 Mya, and orders are 99–323 Mya, which are largely consistent with previous studies. In this study, all phylogenetically supported families were dated, with the families of Agaricomycotina diverging from 27–178 Mya, Pucciniomycotina from 85–222 Mya, and Ustilaginomycotina from 79–177 Mya. Divergence times as additional criterion in ranking provide additional evidence to resolve taxonomic problems in the Basidiomycota taxonomic system, and also provide a better understanding of their phylogeny and evolution.

Microscopic characterization of orchid mycorrhizal fungi: Scleroderma as a putative novel orchid mycorrhizal fungus of Vanilla in different crop systems

Vanilla is an orchid of economic importance widely cultivated in tropical regions and native to Mexico. We sampled three species of Vanilla (V. planifolia, V. pompona, and V. insignis) in different crop systems. We studied the effect of crop system on the abundance, type of fungi, and quality of pelotons found in the roots using light and electron microscopy and direct sequencing of mycorrhizal structures. Fungi were identified directly from pelotons obtained from terrestrial roots of vanilla plants in the flowering stage. Root samples were collected from plants in crop systems located in the Totonacapan area in Mexico (states of Puebla and Veracruz). DNA was extracted directly from 40 pelotons and amplified using ITS rRNA sequencing. Peloton-like structures were observed, presenting a combination of active pelotons characterized by abundant hyphal coils and pelotons in various stages of degradation. The most active pelotons were observed in crop systems throughout living tutors (host tree) in comparison with roots collected from dead or artificial tutors. Fungi identified directly from pelotons included Scleroderma areolatum, a common ectomycorrhizal fungus that has not been reported as a mycorrhizal symbiont in orchids. Direct amplification of pelotons also yielded common plant pathogens, including Fusarium and Pyrenophora seminiperda, especially in those sites with low colonization rates, and where large numbers of degraded pelotons were observed. This research reports for the first time the potential colonization of Vanilla by Scleroderma, as a putative orchid mycorrhizal symbiont in four sites in Mexico and the influence of crop system on mycorrhizal colonization on this orchid.

Basidiospores attach to the seed of Shorea leprosula in lowland tropical dipterocarp forest and form functional ectomycorrhiza on seed germination

This research aimed to study the ectomycorrhiza formed by basidiospores attached to the outer surface of Shorea leprosula (Dipterocarpaceae) seed collected from a lowland tropical dipterocarp forest. Two groups of seeds were collected: control seeds collected from plastic net hanging 2 m above the ground and forest floor seeds collected on the forest floor. Before planting, 15 seeds from each group were observed for basidiospores attached to the seed. Ten of the 3-week-old S. leprosula seedlings of each group were individually grown in 1.5 kg of sterile zeolite for 8 months in a greenhouse. Pots were fertilized with MMN solution containing half the strength of phosphate. Fungal identity, ectomycorrhizal root tip colonization and anatomy, plant growth, and phosphate uptake were measured. The control seeds did not have basidiospores attached, whereas the forest floor seeds had 2 × 10⁵ basidiospores of Tomentella. Bioassay test results indicate that the seedlings from the control seeds did not form ectomycorrhiza, whereas those seedlings from the forest floor seeds formed 3 morphotypes of ectomycorrhizae. Based on ITS1, 5.8S, and ITS2 rDNA region analyses, the 3 morphotypes belonged to Tomentella sp. HBT2, Tomentella sp. HBT4, and Scleroderma sp. HBS3. Root colonization percentage was above 70% for all three morphotypes. Root colonization in general increased plant growth and phosphate uptake. This is the first report of Tomentella basidiospores attached on the seed surface as a functional inoculum and of Tomentella ectomycorrhiza from dipterocarps lowland tropical forest.

Scleroderma areolatum ectomycorrhiza on Fagus sylvatica L

Despite its broad host range and distribution and its potential applications in commercial plantation forests, comprehensive descriptions of Scleroderma ectomycorrhizae are available only for Scleroderma citrinum, Scleroderma bovista and Scleroderma sinnamariense. This study provides a morphological and anatomical description of tree nursery derived ectomycorrhizae of Scleroderma areolatum on Fagus sylvatica, grown for several years in a climatized room. Ectomycorrhizae of S. areolatum were silvery white with abundant rhizomorphs; all mantle layers were plectenchymatous, rhizomorphs of type E, with prominent emanating hyphae with thick cell wall. The distal ends of emanating hyphae of rhizomorphs were inflated and often merged with other emanating hyphae. All parts of the mycorrhiza were clampless. In hyphae of the outer mantle layer, rhizomorphs and emanating hyphae, oily droplets were observed that did not stain in sulfo-vanillin and disappeared in lactic acid after a few hours. Although the phylogenetic analysis positioned the newly described ectomycorrhiza together with Scleroderma verrucosum and Scleroderma cepa in a single clade with a taxon name SH005470.07FU, the ectomycorrhizae of these three species can be morphologically well separated based on rhizomorph type.

Commercial Sphagnum peat moss is a vector for exotic ectomycorrhizal mushrooms

Sphagnum peat moss is one of the most commonly used substrates for forest plant and houseplant production. It is extracted from peat bogs in the circumboreal region and exported worldwide. Commercial peat moss is pasteurized, and is therefore believed to be free of viable ectomycorrhizal propagules. We used a bioassay with Pinus montezumae to demonstrate that commercial peat moss carries viable ectomycorrhizal spores, able to form mycorrhizae. Ectomycorrhizal fungi on seedling root-tips were sequenced for phylogenetic analyses using the ITS rDNA barcode region. We found three species: Suillus brevipes, Sphaerosporella brunnea, and Thelephora terrestris. S. brevipes and T. terrestris were found as viable inoculum transported in the peat moss, while S. brunnea was a greenhouse contaminant. S. brevipes and T. terrestris have biological characteristics (such as heat resistant and long living spores) that facilitate their survival to the extraction, transport, and storage processes of peat moss. This allows them to colonize nursery seedlings and to become potential invasive species in plantation areas. S. brevipes and T. terrestris are two of the most introduced fungi by anthropic activities; it has been argued that the vehicle for the introductions are their pine symbionts. This is the first time it has been demonstrated that peat moss is an important vehicle for the introduction of these fungi; a fact potentially related to the pattern of introduction of these ectomycorrhizal species from the northern hemisphere to elsewhere in the world.

Ectomycorrhizal fungal communities associated to Nothofagus species in Northern Patagonia

Ectomycorrhizal fungi constitute an important component of soil biota in Nothofagus forests in Patagonia. However, ectomycorrhizal fungal community is poorly known in this region. Here, we assess biodiversity and community compositions of ectomycorrhizal fungal species associated with Nothofagus dombeyi, N. obliqua and N. alpina. We selected three monospecific Nothofagus forest sites for each species within the boundaries of the Lanin National Park in Northern Patagonia. Ectomycorrhizal fungal species were identified based on morphotyping and rDNA (ITS and 28S rDNA) sequence analysis using both universal and taxon-specific primers. Contrary to previous studies on congeneric host trees, our results showed no significant differences among Nothofagus forest types in terms of fungal biodiversity and community composition. However, altitude had a strong effect on the structure of the ectomycorrhizal fungal community associated with Nothofagus spp.

Diversity and evolution of ectomycorrhizal host associations in the Sclerodermatineae (Boletales, Basidiomycota)

This study uses phylogenetic analysis of the Sclerodermatineae to reconstruct the evolution of ectomycorrhizal host associations in the group using divergence dating, ancestral range and ancestral state reconstructions. Supermatrix and supertree analysis were used to create the most inclusive phylogeny for the Sclerodermatineae. Divergence dates were estimated in BEAST. Lagrange was used to reconstruct ancestral ranges. BayesTraits was used to reconstruct ectomycorrhizal host associations using extant host associations with data derived from literature sources. The supermatrix data set was combined with internal transcribed spacer (ITS) data sets for Astraeus, Calostoma, and Pisolithus to produce a 168 operational taxonomic unit (OTU) supertree. The ensuing analysis estimated that basal Sclerodermatineae originated in the late Cretaceous while major genera diversified near the mid Cenozoic. Asia and North America are the most probable ancestral areas for all Sclerodermatineae, and angiosperms, primarily rosids, are the most probable ancestral hosts. Evolution in the Sclerodermatineae follows the biogeographic history of disjunct plant communities associated with early Cenozoic mesophytic forests and a boreotropical history. Broad geographic distributions are observed in the most promiscuous Sclerodermatineae (those with broad host ranges), while those with relatively limited distribution have fewer documented ectomycorrhizal associations. This suggests that ectomycorrhizal generalists have greater dispersal capabilities than specialists.