The arbuscular mycorrhizal (AM) fungi are a globally distributed group of soil organisms that play critical roles in ecosystem function. However, the ecological niches of individual AM fungal taxa are poorly understood. We collected > 300 soil samples from natural ecosystems worldwide and modelled the realised niches of AM fungal virtual taxa (VT; approximately species-level phylogroups). We found that environmental and spatial variables jointly explained VT distribution worldwide, with temperature and pH being the most important abiotic drivers, and spatial effects generally occurring at local to regional scales. While dispersal limitation could explain some variation in VT distribution, VT relative abundance was almost exclusively driven by environmental variables. Several environmental and spatial effects on VT distribution and relative abundance were correlated with phylogeny, indicating that closely related VT exhibit similar niche optima and widths. Major clades within the Glomeraceae exhibited distinct niche optima, Acaulosporaceae generally had niche optima in low pH and low temperature conditions, and Gigasporaceae generally had niche optima in high precipitation conditions. Identification of the realised niche space occupied by individual and phylogenetic groups of soil microbial taxa provides a basis for building detailed hypotheses about how soil communities respond to gradients and manipulation in ecosystems worldwide.

• Klíčová slova
• arbuscular mycorrhizal fungi, ecological niche, molecular taxa, niche optimum, niche width, pH, phylogenetic correlation, temperature,
• MeSH
• ekosystém MeSH
• fylogeneze MeSH
• houby MeSH
• koncentrace vodíkových iontů MeSH
• mykorhiza * MeSH
• půda MeSH
• půdní mikrobiologie MeSH
• teplota MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• půda MeSH

Members of the family Pospiviroidae have single-stranded circular RNA genomes that adopt a rod-like or a quasi-rod-like conformation. These genomes contain a central conserved region that is involved in replication in the nucleus through an asymmetric RNA-RNA rolling-circle mechanism. Members of the family Pospiviroidae lack the hammerhead ribozymes that are typical of viroids classified in the family Avsunviroidae. The family Pospiviroidae includes the genera Apscaviroid, Cocadviroid, Coleviroid, Hostuviroid and Pospiviroid, with >25 species. This is a summary of the ICTV Report on the family Pospiviroidae, which is available at ictv.global/report/pospiviroidae.

• Klíčová slova
• ICTV Report, Pospiviroidae, taxonomy,
• MeSH
• genom virový MeSH
• kruhová RNA MeSH
• replikace viru * MeSH
• RNA katalytická genetika   MeSH
• RNA virová genetika   MeSH
• RNA genetika   MeSH
• viroidy klasifikace   genetika   fyziologie   MeSH
• Publikační typ
• časopisecké články MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• hammerhead ribozyme MeSH Prohlížeč
• kruhová RNA MeSH
• RNA katalytická MeSH
• RNA virová MeSH
• RNA MeSH

Members of the family Avsunviroidae have a single-stranded circular RNA genome that adopts a rod-like or branched conformation and can form, in the strands of either polarity, hammerhead ribozymes involved in their replication in plastids through a symmetrical RNA-RNA rolling-circle mechanism. These viroids lack the central conserved region typical of members of the family Pospiviroidae. The family Avsunviroidae includes three genera, Avsunviroid, Pelamoviroid and Elaviroid, with a total of four species. This is a summary of the ICTV Report on the taxonomy of the family Avsunviroidae, which is available at http://www.ictv.global/report/avsunviroidae.

• Klíčová slova
• Avsunviroidae, ICTV, avocado sunblotch viroid, eggplant latent viroid, peach latent mosaic viroid, taxonomy, viroid,
• MeSH
• genom virový MeSH
• kruhová RNA MeSH
• replikace DNA MeSH
• replikace viru * MeSH
• RNA katalytická genetika   MeSH
• RNA virová genetika   MeSH
• RNA genetika   MeSH
• viroidy klasifikace   genetika   fyziologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• hammerhead ribozyme MeSH Prohlížeč
• kruhová RNA MeSH
• RNA katalytická MeSH
• RNA virová MeSH
• RNA MeSH