1. Mycelial communities associated with Ostrya carpinifolia, Quercus pubescens and Pinus nigra in a patchy Sub-Mediterranean Karst woodlandTanja Mrak, Philip Alan Brailey-Crane, Nataša Šibanc, Tijana Martinović, Jožica Gričar, Hojka Kraigher, 2025, original scientific article Abstract: Common mycorrhizal networks of ectomycorrhizal (EcM) fungi could be of great benefit to trees growing in the shallow soils of Sub-Mediterranean Karst ecosystems, potentially playing a crucial role in the survival of trees in this harsh environment. The first step to confirm the existence of such networks is to assess the extent and nature of symbiont sharing in the mycelial community. To address this question, we incubated in-growth mesh bags under the native Ostrya carpinifolia and Quercus pubescens, and the non-native Pinus nigra, over two consecutive years. In Q. pubescens and P. nigra, but not in O. carpinifolia, mycelium production was significantly higher in the year with higher spring precipitation, indicating the influence of climatic conditions, but also the identity of the host tree. We observed a complex interaction between tree species and sampling year in structuring the composition and diversity of mycelial communities. Local environmental conditions contributed additionally and were responsible for 21.46% of the community variation between samples. Although ~ 70% of fungal operational taxonomic units were shared across the studied tree species, distinct community compositions emerged, emphasizing the role of host tree specificity. Q. pubescens exhibited greater stability in EcM richness between sampling years, whereas P. nigra showed lower EcM richness, likely due to limited availability of compatible fungi and reliance on introduced fungal partners. Additionally, differences in EcM fungal exploration strategies were observed. O. carpinifolia and Q. pubescens mainly hosted non-specific EcM fungi with short distance exploration types. In contrast, EcM fungi of P. nigra had higher spatial spread, and were predominantly conifer specific. Overall, our results emphasize the importance of host specificity, soil parameters, spatial proximity, and climatic variability for the structuring of mycelial communities in fragmented forests. Keywords: ectomycorrhizal fungi, mesh bags, exploration strategies, hop-hornbeam, Pubescent oak, European black pine Published in DiRROS: 30.07.2025; Views: 539; Downloads: 352
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2. High spatial but low temporal variability in ectomycorrhizal community composition in Abies alba forest standsTina Unuk Nahberger, Hojka Kraigher, Tine Grebenc, 2025, original scientific article Abstract: The ectomycorrhizal symbionts of silver fir have rarely been analyzed and identified, so little is known about their diversity and distribution. The aim of this study was (1) to analyze the diversity of ectomycorrhizal fungal species in three geographically distinct forest stands of Abies alba and (2) to demonstrate the high temporal variability of the ectomycorrhizal community over two consecutive growing seasons using repeated monthly sampling. Root samples were taken every month during two growing seasons in three silver fir-dominated forest stands. The ectomycorrhizal root tips were first assigned to a morphotype based on morphological characteristics and then identified by sequencing the internal transcribed spacer region. Alpha and beta diversity differed significantly between all three study sites, with the most diverse and even ectomycorrhizal community described in plot Jelovški boršt. The diversity indices over the growing season were different at two of the three study sites, supporting the idea of a fluctuation of ectomycorrhizal taxa during the growing seasons of the two consecutive years. While significant temporal variability was only confirmed for certain ectomycorrhizal taxa, there were no significant changes in the ectomycorrhizal community in general. Thus, we confirmed the high spatial but low temporal variability of the ectomycorrhizal community associated with silver fir. Keywords: ectomycorrhizal community, spatiotemporal variation, silver fir, fungal diversity, forest, root-associated fungi Published in DiRROS: 31.01.2025; Views: 641; Downloads: 453
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3. Experimental drought results in a decline of ectomycorrhizae of Quercus pubescens Willd.Tanja Mrak, Tina Unuk Nahberger, Olivera Maksimović, Hojka Kraigher, Mitja Ferlan, 2025, original scientific article Abstract: Experimental drought decreased the vitality of ectomycorrhiza and reduced the number of unique morphotypes. Quercus pubescens (Willd.) is an ectomycorrhizal (ECM) tree species that is capable of withstanding occasional drought events, but the response of its ectomycorrhiza to drought is not well known. An experiment with two rain exclusion plots and two natural precipitation regime plots was established in a secondary sub-Mediterranean oak forest. ECM roots were sampled before the experiment and after 11 months of rain exclusion. ECM root tips were divided into vital and non-vital and quantified. Morphoanatomical characterization and molecular identification were performed for vital ectomycorrhizae to obtain diversity indices and perform community analyses. Soil water content (SWC) in rain exclusion plots was reduced by approx. 6 vol.% relative to natural precipitation regime and was devoid of major peaks in SWC after rain events. After 11 months, ECM vitality and species richness were significantly reduced on rain exclusion plots compared to the natural precipitation regime while ECM community was reduced to a small subset of the most frequent morphotypes, with strongly decreased number of the unique morphotypes. The reduction of unique morphotypes as a result of rain exclusion may compromise the functional diversity of ectomycorrhiza in their role of nutrient uptake, while the reduction of ECM vitality may decrease the absorptive surface for water and nutrients. Keywords: ectomycorrhizal fungi, Pubescent oak, Sub-Mediterranean, karst, drought stress, rain exclusion Published in DiRROS: 12.12.2024; Views: 887; Downloads: 230
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4. How beech provenance affects the structure of secondary xylem, leaf traits, and the ectomycorrhizal community under optimal growth conditionsTanja Mrak, Jožica Gričar, Tina Unuk Nahberger, Gregor Božič, Luka Krajnc, Peter Prislan, Domen Arnič, Tom Levanič, Hojka Kraigher, 2024, original scientific article Abstract: Beyond growth parameters and drought tolerance, comparatively little is known about the functioning of different beech (Fagus sylvatica L.) provenances. We investigated properties of leaves, stem secondary xylem, and ectomycorrhiza (ECM), and explored their interdependencies to identify the best performing beech provenance in optimal growth conditions. The study was conducted on 23-year-old trees in a provenance trial. The investigated provenances originated from Atlantic (Belgium—BE), Alpine (Italy—IT, Slovenia—SI), and continental climates (the Czech Republic—CZ). A significant effect of provenance was observed for stem vessel diameters and conductive area, as well as for foliar %C, δ13C, δ15N, and δ18O. δ13C as a proxy of intrinsic water use efficiency (iWUE) showed that the highest iWUE was achieved in BE provenance. Individuals with a better iWUE had wider growth rings regardless of provenance. Better iWUE was associated with lower specific leaf area (SLA). ECM community composition and diversity indices did not differ significantly among the provenances. Specific ECM taxa were associated with individuals with high SLA, δ13C, δ15N, and δ18O. In optimal growth conditions with no stress events, BE is a promising provenance due to an efficient water conducting system with high vessel diameters and conductive area, and high iWUE, while Alpine provenances showed an adaptation of their water conducting system to freezing conditions at their original locations. Integrating findings from different compartments improves our understanding of functioning of different beech provenances. Keywords: Fagus sylvatica, provenance trial, stable isotopes, specific leaf area, xylem vessels, ectomycorrhizal fungi Published in DiRROS: 19.04.2024; Views: 1323; Downloads: 1335
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5. Buckwheat milling waste effects on root morphology and mycorrhization of Silver fir seedlings inoculated with Black Summer Truffle (Tuber aestivum Vittad.)Tina Unuk Nahberger, Tine Grebenc, Daniel Žlindra, Tanja Mrak, Matevž Likar, Hojka Kraigher, Zlata Luthar, 2022, original scientific article Abstract: Large amounts of buckwheat waste are generated annually by the industry and are used in several different ways. To date, there has been little research regarding its suitability as a medium for growing seedlings in nurseries. The aim of this study was therefore to analyze the suitability of common and Tartary buckwheat wastes (brans and husks) as media used for raising seedlings. A pot experiment with five different treatments was carried out, in which silver fir root parameters were analyzed and compared 6 and 12 months after summer truffle-spore inoculation. A significantly higher concentration of the antioxidant rutin was confirmed in Tartary buckwheat bran compared to other buckwheat waste used. We also confirmed a significantly positive effect of added Tartary buckwheat husks on specific root length, root tip density, and specific root tip density compared to added common buckwheat husks or Tartary buckwheat bran, for which a significantly negative effect on branching density was confirmed. A significantly negative effect of added buckwheat husks and Tartary buckwheat bran was confirmed for summer truffle mycorrhization level. Keywords: buckwheat waste, root growth, summer truffle, forest nursery, silver fir, inoculation with ectomycorrhizal fungi Published in DiRROS: 09.02.2022; Views: 2669; Downloads: 1446
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6. Not every edible orange milkcap is Lactarius deliciosus : first record of Lactarius quieticolor (sect. Deliciosi) from BrazilAlexandre G. S. Silva-Filho, Marcelo Aloisio Sulzbacher, Tine Grebenc, Felipe Wartchow, 2020, original scientific article Keywords: ectomycorrhizal fungi, edible mushroom, Russulaceae, Pinaceae, pine plantation Published in DiRROS: 14.01.2021; Views: 2030; Downloads: 1496
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