Many orchid species are endangered due to anthropogenic pressures such as habitat destruction and overharvesting, meanwhile, all orchids rely on orchid mycorrhizal fungi (OMF) for seed germination and seedling growth. Therefore, a better understanding of this intimate association is crucial for orchid conservation. Isolation and identification of OMF remain challenging as many fungi are unculturable. In our study, we tested the efficiency of both culture-dependent and culture-independent methods to describe OMF diversity in multiple temperate orchids and assessed any phylogenetic patterns in cultivability. The culture-dependent method involved the cultivation and identification of single pelotons (intracellular hyphal coils), while the culture-independent method used next-generation sequencing (NGS) to identify root-associated fungal communities. We found that most orchid species were associated with multiple fungi, and the orchid host had a greater impact than locality on the variability in fungal communities. The culture-independent method revealed greater fungal diversity than the culture-dependent one, but despite the lower detection, the isolated fungal strains were the most abundant OMF in adult roots. Additionally, the abundance of NGS reads of cultured OTUs was correlated with the extent of mycorrhizal root colonization in orchid plants. Finally, this limited-scale study tentatively suggests that the cultivability character of OMF may be randomly distributed along the phylogenetic trees of the rhizoctonian families.

• Keywords
• Ceratobasidiaceae, Orchidaceae, Serendipitaceae, Tulasnellaceae, culture-independent and -dependent methods, fungal phylogeny, metabarcoding, mycorrhizal fungi,
• Publication type
• Journal Article MeSH

Ericoid mycorrhiza represents a key adaptation of the Ericaceae plants to facilitate their establishment in harsh conditions. The Ericaceae are a large family of flowering plants, with global distribution. However, our current knowledge about the ericoid mycorrhizal fungal diversity and ecology largely relates to the Northern Hemisphere. Our study focused on the assembly of root-associated fungal (RAF) communities of Erica dominans in two types of microhabitats of contrasting moisture along an elevation gradient in Drakensberg mountains in South Africa. RAF communities were determined by 454-sequencing of the internal transcribed spacer (ITS) region of ribosomal DNA. The majority of RAF showed affinity to the orders Helotiales, Pezizales, and Pleosporales. Microhabitat type as well as elevation had significant but weak effect on RAF community composition. We identified two putative ericoid mycorrhizal fungi, the ecological niches of which were differentiated between the studied microhabitats. Our study also provides one of the first comprehensive data about RAF communities of Ericaceae on African continent and shows the occurrence of the most studied ericoid mycorrhizal fungus Pezoloma ericae (belonging to P. ericae aggregate) in roots of Ericaceae host plant in Africa.

• Keywords
• Biogeography, DSE, Ericaceae, Fungal ecology, Mycorrhizal symbiosis,
• MeSH
• Ericaceae microbiology   MeSH
• Plant Roots microbiology   MeSH
• Mycorrhizae classification   physiology   MeSH
• Soil * MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• South Africa MeSH
• Names of Substances
• Soil * MeSH

Orchid mycorrhizal (OrM) fungi play a crucial role in the ontogeny of orchids, yet little is known about how the structure of OrM fungal communities varies with space and environmental factors. Previous studies suggest that within orchid patches, the distance to adult orchids may affect the abundance of OrM fungi. Many orchid species grow in species-rich temperate semi-natural grasslands, the persistence of which depends on moderate physical disturbances, such as grazing and mowing. The aim of this study was to test whether the diversity, structure and composition of OrM fungal community are influenced by the orchid patches and management intensity in semi-natural grasslands. We detected putative OrM fungi from 0 to 32 m away from the patches of host orchid species (Orchis militaris and Platanthera chlorantha) in 21 semi-natural calcareous grasslands using pyrosequencing. In addition, we assessed different ecological conditions in semi-natural grasslands but primarily focused on the effect of grazing intensity on OrM fungal communities in soil. We found that investigated orchid species were mostly associated with Ceratobasidiaceae and Tulasnellaceae and, to a lesser extent, with Sebacinales. Of all the examined factors, the intensity of grazing explained the largest proportion of variation in OrM fungal as well as total fungal community composition in soil. Spatial analyses showed limited evidence for spatial clustering of OrM fungi and their dependence on host orchids. Our results indicate that habitat management can shape OrM fungal communities, and the spatial distribution of these fungi appears to be weakly structured outside the orchid patches.

• Keywords
• Calcareous grassland, Fungal community composition, Grazing intensity, Next-generation sequencing, Orchid mycorrhiza, Spatial distribution,
• MeSH
• Basidiomycota MeSH
• Phylogeny MeSH
• Mycorrhizae classification   MeSH
• Orchidaceae microbiology   MeSH
• Grassland * MeSH
• Soil Microbiology * MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Estonia MeSH