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Our study delved into the relationship between root‐associated fungi, gene expression and plant morphology in Norway spruce cuttings derived from both slow‐and fast‐growing trees. We found no clear link between the gene expression patterns of adventitious roots and the growth phenotype, suggesting no fundamental differences in the receptiveness to fungal symbionts between the phenotypes. Interestingly, saplings from slow‐growing parental trees exhibited a higher richness of ectomycorrhizal species and larger roots. Some ectomycorrhizal species, typically found on mature spruces, were more prevalent on saplings from slow‐growing spruces. The ericoid mycorrhizal fungus, Hyaloscypha hepaticola, showed a stronger association with saplings from fast‐growing spruces. Moreover, saplings from slow‐growing spruces had a greater number of Ascomycete taxa and free‐living saprotrophic fungi. Aboveground sapling stems displayed some phenotypic variation; saplings from fast‐growing phenotypes had longer branches but fewer whorls in their stems compared to those from the slow‐growing group. In conclusion, the observed root‐associated fungi and phenotypic characteristics in young Norway spruces may play a role in their long‐term growth rate. This suggests that the early interactions between spruces and fungi could potentially influence their growth trajectory. [ABSTRACT FROM AUTHOR]

A decline in the carbon content of agricultural soils has been reported globally. Amendments of forest industry side-streams might counteract this. We tested the effects of industrial conifer bark and its cascade process materials on the soil microbiome under barley (Hordeum vulgare L.) in clay and silt soil microcosms for 10 months, simulating the seasonal temperature changes of the boreal region. Microbial gene copy numbers were higher in clay soils than in silt. All amendments except unextracted bark increased bacterial gene copies in both soils. In turn, all other amendments, but not unextracted bark from an anaerobic digestion process, increased fungal gene copy numbers in silt soil. In clay soil, fungal increase occurred only with unextracted bark and hot water extracted bark. Soil, amendment type and simulated season affected both the bacterial and fungal community composition. Amendments increased bacteria originating from the anaerobic digestion process, as well as dinitrogen fixers and decomposers of plant cells. In turn, unextracted and hot water extracted bark determined the fungal community composition in silt. As fungal abundance increase and community diversification are related to soil carbon acquisition, bark-based amendments to soils can thus contribute to sustainable agriculture. [ABSTRACT FROM AUTHOR]

We assessed the soil carbon sequestration potential of various organic amendments of agricultural, municipal and industrial origin and the applicability of a soil carbon model to simulate it. The chemical composition of a large number of plant residues, manures, composts, digestates and biochars was determined and selected materials were incubated in soil to assess their decomposition rates and effects on soil microbial community structure. Decomposability was strongly correlated with the initial chemical composition determined by water, ethanol and acid extraction. Fresh plant materials decomposed the fastest, roots decomposed more slowly than aboveground biomass and processing decreased the decomposability of the materials. Soil carbon model Yasso07 predicted the decomposition of the amendments relatively well, except for fresh plant litter and fiber sludge from the pulp and paper industry which decomposed considerably faster than predicted by the model. Differences in the studied materials were also reflected in the soil microbial and fungal community composition. Plant root addition to laboratory microcosms induced a different soil microbial community compared to organic materials originating from the forest industry. Typical application rates of the studied amendments result in carbon sequestration at a rate sufficient to reach the goal of the 4/1000 initiative. The results can be used to select the most efficient measures to sequester carbon in croplands and to report the effects of practices like cover crop cultivation or organic matter addition. [ABSTRACT FROM AUTHOR]

Phenotypic diversity within plant species is crucial to shaping evolutionary responses of populations and interactions among species, yet intraspecific genetic variability notably in roots has attracted little attention. Further, evidence for the root–shoot trait synchronisation remains inconclusive, narrowing our understanding of the role that belowground traits play in local adaptation. We applied broad 'top‐to‐toe' phenotyping to a model system whose native environmental conditions were simulated in experimental settings. Fifteen maternal families of Norway spruce Picea abies from southern Finland grew in six combinations of two simulated growing seasons and three soil treatments. We scored variation in 25 functional traits, including size, architecture and morphology of intact root systems, and shoot growth and phenology. Careful phenotyping of roots uncovered five trait dimensions, with root size, architecture and morphology forming the three largest axes of variation. Dimensions varied in their treatment responses. We observed among‐family differences in all trait dimensions, marking substantial within‐population genetic diversity. For example, average total root length varied almost twofold among families, but family × soil interactions indicated treatment‐specific estimates of genetic variance. Mirroring root traits, phenotypic plasticity and genetic variation characterised shoot growth and phenology. In all, the complete phenotypic dataset yielded six trait dimensions, with assorted measures of root system and shoot size composing the main axis of variation. Although plastic and genetically variable, root architecture and morphology were not associated with shoot growth in any treatment. Also phenology and root‐to‐shoot ratio were detached from the primary axis of trait variability. Our results demonstrate that complex within‐species patterns of trait covariation can be observed even locally and that phenotypic variation in independent trait dimensions reflecting divergent growth strategies is under genetic control. More accurate predictions of population and species responses to changes in the environment can be achieved when such intraspecific diversity is taken into account. [ABSTRACT FROM AUTHOR]

In 2010, dieback of Norway spruce (Picea abies) was observed in Latvia. As mostly stands on seasonally or permanently water-saturated soils were damaged, we hypothesized that the recorded foliar damage might be associated with belowground factors. We established 48 sample plots in stands with damage symptoms for soil parameter evaluation and fine root sampling to determine the number of fine roots in different growth stages and to describe the associated fungal community. Among sample plots on organic soils, there were fewer viable older fine roots and greater number of dead fine roots in more damaged sites than in less damaged. These root parameters were significantly correlated with higher groundwater level and soil pH. The fungal community was dominated by ectomycorrhizal (ECM) species (the most common wasTylospora asterophora), the endophyteOidiodendron maiusand saprotrophic speciesCryptococcus magnus. Saprotrophic species had higher abundance in more damaged sites, suggesting a shift in fungal communities from ECM fungi. In conclusion, the results of this work suggest Norway spruce root system response to short-term climatic stress, which should be considered when planning spruce forest management, especially on organic soils with a high groundwater level. [ABSTRACT FROM AUTHOR]

Abstract: This study investigated fungal endophytes in the needles of Norway spruce (Picea abies) cuttings in relation to host tree growth. We also determined the prevalence of endophytes in needles incubated for six months. The cuttings originated from clonal origins showing slow- and fast-growth in long-term field trials but the heritable differences in growth rate were not yet detected among the studied cutting. Endophytes were isolated from surface-sterilized needles with culture-free DNA techniques. No significant differences were observed between endophyte communities of slow- and fast-growing clonal origins. However, the endophyte community correlated with the current growth rate of cuttings suggesting that endophytes reflect short- rather than long-term performance of a host. The concentration of condensed tannins was similar in slow- and fast-growing clonal origins but it showed a negative relationship with endophyte species richness, implying that these secondary compounds may play an important role in spruce tolerance against fungal infections. More than a third of endophyte species were detected in both fresh and decomposing needles, indicating that many needle endophytes are facultative saprotrophs. Several potentially pathogenic fungal species were also found within the community of saprotrophic endophytes. [Copyright &y& Elsevier]

We studied the role of taxonomical and functional ectomycorrhizal ( ECM) fungal diversity in root formation and nutrient uptake by Norway spruce ( Picea abies) seedlings with fast- and slow-growing phenotypes., Seedlings were grown with an increasing ECM fungal diversity gradient from one to four species and sampled before aboveground growth differences between the two phenotypes were apparent. ECM fungal colonization patterns were determined and functional diversity was assayed via measurements of potential enzyme activities of eight exoenzymes probably involved in nutrient mobilization., Phenotypes did not vary in their receptiveness to different ECM fungal species. However, seedlings of slow-growing phenotypes had higher fine-root density and thus more condensed root systems than fast-growing seedlings, but the potential enzyme activities of ectomycorrhizas did not differ qualitatively or quantitatively. ECM species richness increased host nutrient acquisition potential by diversifying the exoenzyme palette. Needle nitrogen content correlated positively with high chitinase activity of ectomycorrhizas., Rather than fast- and slow-growing phenotypes exhibiting differing receptiveness to ECM fungi, our results suggest that distinctions in fine-root structuring and in the belowground growth strategy already apparent at early stages of seedling development may explain later growth differences between fast- and slow-growing families. [ABSTRACT FROM AUTHOR]

Abstract: Endophytic fungi show no symptoms of their presence but can influence the performance and vitality of host trees. The potential use of endophytes to indicate vitality has been previously realized, but a standard protocol has yet to be developed due to an incomplete understanding of the factors that regulate endophyte communities. Using a culture-free molecular approach, we examined the extent to which host genotype influences the abundance, species richness, and community composition of endophytic fungi in Norway spruce needles. Briefly, total DNA was extracted from the surface-sterilized needles of 30 clones grown in a nursery field and the copy number of the fungal internal transcribed spacer (ITS) region of ribosomal DNA was estimated by quantitative PCR. Fungal species richness and community composition were determined by denaturing gradient gel electrophoresis and DNA sequencing. We found that community structure and ITS copy number varied among spruce clones, whereas species richness did not. Host traits interacting with endophyte communities included needle surface area and the location of cuttings in the experimental area. Although Lophodermium piceae is considered the dominant needle endophyte of Norway spruce, we detected this species in only 33 % of samples. The most frequently observed fungus (66 %) was the potentially pathogenic Phoma herbarum. Interestingly, ITS copy number of endophytic fungi correlated negatively with the richness of ectomycorrhizal fungi and thus potential interactions between fungal communities and their influence on the host tree are discussed. Our results suggest that in addition to environmental factors, endophyte communities of spruce needles are determined by host tree identity and needle surface area. [Copyright &y& Elsevier]

Long-term effects of organic and conventional farming systems in parallel on the microbiota of boreal arable soil from forage and cereal crop fields were investigated. Microbial activity was measured as basal respiration and microbial biomass C and N were determined by fumigation extraction. Microbial abundance was determined by gene copy numbers from bacterial and archaeal specific 16S rRNA genes and the fungal ITS2 region with quantitative PCR. Microbial community composition for soil bacteria and fungi, including arbuscular mycorrhiza, were conducted by amplicon sequencing with richness assessed from OTU reads. We detected changes in both bacterial and fungal community composition between the farming systems. Microbial activity and biomass C and N were higher in the organic system for cereal crop rotation compared to the respective conventional system. In the autumn, organic systems had higher microbial richness. As fungi were more abundant in the autumn, they may be responsible for both higher microbial activity and C sequestration in their biomass after harvesting, especially in the organic system for cereal crop rotation. Also, crop type and cow manure explained changes in fungal community composition. The typical bacterial community of the organic system for cereal crop rotation included many soil and plant health promoting bacterial groups. Fungi benefiting from organic farming practices, other than manure, may include endophytic taxa with a variety of functions as well as pathogenic and mycotoxin producing species. Overall, the results suggest that farming practices typical of organic farming, such as use of green manure and continuous plant cover have induced changes in the soil microbiome. • Farming system induced changes in bacterial and fungal community composition in cereal and forage crop rotations. • Organic systems possessed higher microbial richness compared to conventional systems in autumn. • Organic system for cereal crop rotation had higher microbial activity and biomass than in the conventional system. • Organic system for cereal crop rotation had more indicator microbes than the respective conventional system. • Organic system for cereal crop rotation contained many soil and plant health promoting bacteria as indicator species. [ABSTRACT FROM AUTHOR]

Northern peatlands are often dominated by ericaceous shrub species which rely on ericoid mycorrhizal fungi (ERM) for access to organic sources of nutrients, such as nitrogen (N) and phosphorus (P), and host abundant dark septate endophytes (DSE). Relationships between hosts and fungal symbionts may change during deposition of anthropogenic N and P. We studied the long-term effects of N and P addition on two ericaceous shrubs, Calluna vulgaris and Erica tetralix , at Whim Bog, Scotland by analyzing fungal colonization of roots, enzymatic activity, and fungal species composition. Unexpectedly, the frequency of typical ERM intracellular colonization did not change while the occurrence of ERM hyphae tended to increase and DSE hyphae to decrease. Our findings indicate that altered nutrient limitations shift root associated fungal colonization patterns as well as affect ericaceous root enzyme activity and thereby decomposition potential. Reduction of recalcitrant fungal biomass in melanized DSE may have implications for peatland C sequestration under nutrient addition. • Long-term effects of N/NP on ericaceous root fungal colonization & enzymatic activity. • ERM intracellular colonization unchanged, ERM hyphae increased & DSE hyphae decreased. • Loss of recalcitrant fungal biomass in melanized DSE may reduce peatland C sink. • Nitrate reduced C. vulgaris root enzyme activity, suggests host/symbiont sensitivity. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal fungi (AMF) enhance plant phosphorus uptake, increase soil water holding abilities, reduce soil erosion and can protect their hosts from soil-borne pathogens. Hence, AMF play an important part in improving sustainable agricultural practices, and information about the effects of different preceding crop species on the following crop's AMF well-being is crucial for designing crop rotations. We studied onion root and soil microbial diversity and onion root AMF colonization rates after being preceded by three AMF hosting and one non-hosting green manure crop species in a boreal climate organic field. One-season cultivation of different preceding green manure crops did not have a strong effect on AMF colonization or microbial diversity in onion roots nor in the surrounding soil. Onions had high AMF colonization and microbial diversity after all four preceding crops. The overall fungal and bacterial populations of the soil reacted more strongly to seasonal variations than preceding crops. The study suggests that one season is a too short time to influence the AMF community in boreal climate organic fields with conventional tillage. Thus, non-host preceding crops can also be used in rotations, especially together with AMF host crops. • For organic onion cultivation AMF non-hosts can be used in rotations under conventional tillage. • One-year cultivation of different crops does not affect soil microbial community structure in boreal fields. • Bare soil during winter period uniforms the soil microbial communities. [ABSTRACT FROM AUTHOR]

Short-term agronomic and environmental benefits are fundamental factors in encouraging farmers to use biochar on a broad scale. The short-term impacts of forest residue biochar (BC) on the productivity and carbon (C) storage of arable boreal clay soil were studied in a field experiment. In addition, rain simulations and aggregate stability tests were carried out to investigate the potential of BC to reduce nutrient export to surface waters. A BC addition of 30 t ha−1 increased soil test phosphorus and decreased bulk density in the surface soil but did not significantly change pH or water retention properties, and most importantly, did not increase the yield. There were no changes in the bacterial or fungal communities, or biomasses. Soil basal respiration was higher in BC-amended plots in the spring, but no differences in respiration rates were detected in the fall two years after the application. Rain simulation experiments did not support the use of BC in reducing erosion or the export of nutrients from the field. Of the C added, on average 80% was discovered in the 0–45 cm soil layer one year after the application. Amendment of boreal clay soil with a high rate of BC characterized by a moderately alkaline pH, low surface functionalities, and a recalcitrant nature, did not induce such positive impacts that would unambiguously motivate farmers to invest in BC. BC use seems unviable from the farmer's perspective but could play a role in climate change mitigation, as it will likely serve as long-term C storage. Unlabelled Image • Forest residue biochar significantly increased carbon stored in soil. • Biochar amendment was not effective in reducing leaching of nutrients. • Biochar did not change the clay soil water retention properties. • Soil bacterial or fungal communities were not changed. • A high biochar dose did not induce such positive impacts that would benefit farmers. [ABSTRACT FROM AUTHOR]