Temporal studies that would offer insight into resilience of ectomycorrhizal (ECM) communities in stress prone climates are scarce despite their role in tree nutrition and water supply. Our study characterized the vitality, community composition, diversity, and function of Quercus pubescens Willd. ECM fungi in the Sub-Mediterranean stress-prone environment for 2 consecutive years (June 2016–May 2018) and related the investigated measures to environmental parameters. ECM community was assessed for species actively associating with root tips and exploring the soil volume through the assessment of mycelial ingrowth into sand-filled mesh bags. The investigated period was characterized by a drier than average summer combined with wildfire in 2016 followed by another dry summer in 2017. The vital to non-vital ECM root tip ratio decreased below one in August 2016 and remained low until January 2018. This was ascribed to a series of stress events that occurred at the site including sequential droughts and wildfire. The most abundant ECM lineages on root tips were Tomentella and other Thelephoraceae, Sebacina, and Cenococcum while in mesh bags the most abundant were Tomentella, Sebacina, Pseudotomentella, Pyronemataceae, Inocybe, Cortinarius, Agaricales, and Boletales lineages. High intra-site variability was observed, with ECM communities directly associated with root tips and exploring the soil volume varying significantly among the plots. Community composition was stable over time, while species richness varied with mean air and soil temperature, relative air humidity, and solar radiation. The most abundant exploration type observed at this site was short distance, which was associated with precipitation along with long distance exploration type. The medium distance exploration type was temporally variable and responded to soil temperature and relative air humidity reflecting seasonality at the site. The presented results indicate complex relationships between environmental parameters, abiotic stress, and ECM fungi.

Vertical ectomycorrhizal (ECM) community composition was assessed on silver fir ( Abies alba Mill.) in beech-silver fir forests in Bosnia and Herzegovina. Organic and upper mineral horizons were described by pedological analyses. Silver fir root tips were divided into vital ECM, old and non-mycorrhizal for each horizon separately. Morpho-anatomical classification of vital ECM root tips with an assessment of abundance was followed by ITS-based molecular characterization and classification into exploration types. The percentage of vital ECM root tips was not affected by the soil horizon. Altogether, 40 ECM taxa were recorded. Several taxa have not previously been reported for silver fir: Hebeloma laterinum , Inocybe fuscidula , I. glabripes , Lactarius acris , L. albocarneus , L. blennius , L. fluens , Ramaria bataillei , Russula badia , R. lutea , R. mairei , Sistotrema sp., Tarzetta catinus, Tomentella atroarenicolor , T. badia , T. cinerascens , T. bryophylla , and T. ramosissima , indicating high potential for diversity of ECM fungi in silver fir stands. No significant differences in community composition and species richness and diversity were detected between mineral and organic horizons. Community composition was affected by CaCO 3 , organic carbon concentration, organic carbon stock, total nitrogen stock, C/N ratio and soil bulk density. No significant effects of soil parameters were detected for exploration types. The contact exploration type was dominant in both soil horizons. Significantly different relative abundances of dominant taxa Tomentella stuposa , Cenococcum geophilum and Piloderma sp. 1 were detected in the two horizons. Twelve taxa were limited to the organic horizon and eight to the mineral horizon.

Effects on roots due to ozone and/or soil water deficit often occur through diminished belowground allocation of carbon. Responses of root biomass, morphology, anatomy and ectomycorrhizal communities were investigated in seedlings of three oak species: Quercus ilex L., Q. pubescens Willd. and Q. robur L., exposed to combined effects of elevated ozone (ambient air and 1.4 x ambient air) and water deficit (100% and 10% irrigation relative to field capacity) for one growing season at a free-air ozone exposure facility. Effects on root biomass were observed as general reduction in coarse root biomass by-26.8% and in fine root biomass by-13.1% due to water deficit. Effect on coarse root biomass was the most prominent in Q. robur (-36.3%). Root morphological changes manifested as changes in proportions of fine root (<2 mm) diameter classes due to ozone and water deficit in Q. pubescens and due to water deficit in Q. robur. In addition, reduced fine root diameter (-8.49%) in Q. robur was observed under water deficit. Changes in root anatomy were observed as increased vessel density (+18.5%) due to ozone in all three species, as reduced vessel tangential diameter (-46.7%) in Q. ilex due to interaction of ozone and water, and as generally increased bark to secondary xylem ratio (+47.0%) due to interaction of ozone and water. Water deficit influenced occurrence of distinct growth ring boundaries in roots of Q. ilex and Q. robur. It shifted the ectomycorrhizal community towards dominance of stress-resistant species, with reduced relative abundance of Tomentella sp. 2 and increased relative abundances of Sphaerosporella brunnea and Thelephora sp. Our results provide evidence that expression of stress effects varies between root traits; therefore the combined analysis of root traits is necessary to obtain a complete picture of belowground responses. (C) 2018 Elsevier B.V. All rights reserved.

Drought is an environmental stress that impacts plant productivity. Projections show both an increase in intense rain events and a reduction in the number of rain days, conditions that leads to increased risk of drought. Consequently, the identification of molecular biomarkers suitable for evaluating the impact of water deprivation conditions on forest plant seedlings is of significant value for monitoring purposes and forest management. In this study, we evaluated a biochemical methodology for the assessment of drought stress coupled with variable soil temperature in European beech (Fagus sylvatica L.) seedlings by analyzing a set of metabolites and enzymes involved in free radical scavenging and cell wall synthesis. The results indicate that the specific activities and isoform profile of superoxide dismutases and glutathione peroxidases together with the variation of phenolic compounds enable discrimination between seedlings with different degrees of photosynthetic activity. This approach represents a promising platform for the assessment of drought stress in forest trees and could serve for enhancing selection and breeding practices, allowing for plants that are more tolerant of abiotic stress.

Simbioza med ektomikoriznimi glivami in gozdnimi drevesi prispeva k rasti dreves in delovanju ekosistema. Ektomikorizne glive so razvile visoko diferencirane strukture, ki omogočajo različne načine privzemanja hranilnih snovi in transport le teh do korenin. Aktivnost fosfataz v mikoriznih glivah omogoča dostopnost fosfatnih spojin v tleh, do katerih rastline sicer nimajo dostopa. V raziskavi smo analizirali aktivnost na površino hif vezane fosfataze (SBP) mikoriznih gliv pri sadikah bukve (Fagus sylvatica L.) in predstavili metodo za zajemanje in analizo slik fosfatazne aktivnosti. Uporabili smo dvofotonski konfokalni laserski mikroskop LSM 7 MP, ki omogoča zajemanje slik od površine mikoriznega plašča skozi mikorizni plašč vse do površine koreninskih celic. Koreninske vršičke smo obarvali s komercialnim barvilom ELF® 97. Slike smo analizirali s prosto dostopnim programom ImageJ. V članku smo pod- robno opisali postopek analize in predstavili prednosti in slabosti izbrane metode. Ključne besede: na površino vezana fosfataza, eksploracijski tipi, fosfat, ELF® 97, bukevThe ectomycorrhizal symbiosis of forest trees contributes to the function of ecosystem and tree growth. The symbiotic organs of ectomycorrhiza (ECM) are highly differentiated structures differing in nutrient uptake, transfer capacities and ability to promote tree growth. In the present study surface-bound phosphatase activity (SBP) was analyzed on ectomycorrhiza of beech seedlings (Fagus sylvatica L.). The method for images acquisition and their analysis was discussed. Two-photon confocal laser scanning microscope LSM 7 MP was used to study spatial distribution of SBP enzymatic activity in various thicknesses of ECM mantle in intact (non-sectioned) ECM root tips. ELF® 97 was used for staining phosphatase enzymes. Images were analyzed using the freely available program ImageJ. In this article, we describe in detail the analysis procedure and the advantages and disadvantages of the method. Key words: surface-bound phosphatase, exploration types, phosphate, ELF® 97, beech

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.

Climate development models predict alterations that will critically influence plant metabolism in southern and central Europe. Although the molecular players involved in the response to climatic stress factors have been well described in crops, little information is available for forest tree species. Consequently, the identification of molecular biomarkers suitable for evaluating the actual impact of different environmental stress conditions on forest plants would be of great importance for monitoring purposes and forest management. In this study, we evaluated a biochemical methodology for the assessment of temperature stress in European beech (Fagus sylvatica L.) and Scots pine (Pinus sylvestris L.) seedlings by analyzing a set of metabolites and enzymes involved in free radical scavenging and cell wall synthesis. The results indicate that the combined analysis of the specific activities and isoform profile of peroxidases, superoxide dismutases, and glutathione peroxidases coupled with the amount variation of phenolic compounds enabled the discrimination between stressed and control seedlings. This approach represents a promising platform for the assessment of temperature stress in forest trees and could also enhance selection and breeding practices, allowing for plants more tolerant and (or) resistant to abiotic stress.

European beech (Fagus sylvatica L.) is an economically and ecologically important forest tree species in Europe. Expected future temperature increases due to global climate change may significantly affect growth of beech trees and consequently influence carbon cycling in beech forests. We tested the hypothesis that soil temperature influences the growth of both belowground and aboveground parts of beech seedlings. One-year-old seedlings were transferred into rhizotrons and subjected to two different soil temperatures for 2 years while the soil moisture level was kept constant. The main effect of the soil temperature was a changed biomass of the woody part of the seedlings. Soil temperature significantly influenced the biomass of shoots and roots and diameter of the stem, which were the highest for the seedlings grown in conditions of soil temperatures maintained in the range of summer soil temperatures from the site of origin of the seedlings. Increased soil temperature also resulted in increased specific root length and specific root tip density. Root-to-shoot ratio and leaf parameters (leaf mass, number of leaves, and specific leaf area), except for leaf area ratio, were not influenced by soil temperature.

Complete List of Authors: Popovic, Milica; Faculty of Chemistry, University of Belgrade, Department of Biochemistry; University of Nova Gorica, Center for biomedical sciences and engineering Sustar, Vid; University of Nova Gorica, Center for biomedical sciences and engineering Gricar, Jozica; Slovenian Forestry Institute, Štraus, Ines; Slovenian Forestry Institute, Torkar, Gregor; Laboratory for Environmental Research, University of Nova Gorica, Vipavska 13, SI-5000 Nova Gorica, Slovenia; Faculty of Education, University of Ljubljana, Kardeljeva pl. 16, SI-1000 Ljubljana, Slovenia Kraigher, Hojka; Slovenian Forestry Institute, de Marco, Ario; University of Nova Gorica, Center for biomedical sciences and engineering

Natural processes or human activities affect environmental conditions, as reflected in the structure of the communities and the level of ectomycorrhizalfungi. The aim of the study was to determine the potential impacts of several temperature regimes of air and soil (substrate) on the occurrence and species diversity of ectomycorrhizal fungi in symbiosis and in the substrate. For this purpose, we analyzed the occurrence of types of ectomycorrhizae on beech seedlings in rhizotrons exposed to four different environmental temperature conditions: 1) air 15-25°C, 2) air 15-25°C in combination with cooling of roots for 5°C, 3) elevated air temperature from 30-50°C, and 4) ambiental conditions (air temperature in Ljubljana). Types of ectomycorrhizae were identified with a combined approach of anatomical morphological characterisation and with analysis of molecular markers (ITS1-5.8S rDNA-ITS2 ribosomal region in rDNA). We identified a total of 6 types of ectomycorrhizae on 51 root tips on 40 beech seedlings. The diversity of ectomycorrhizal types was the highest in terms of near-optimal growth conditions of beech. Most similar as far as species diversity of ectomycorrhizal fungi are concerned were the experiments with air temperature of 15-25°C with or without cooling of the root system. The commonest ectomycorrhizal species was Hebeloma sacchariolens, which was also the most commonly seen species in fine roots of dead plants. Selected species of ectomycorrhizal fungi were further substantiated with DGGE method in all analyzed substrate samples.