Biology subjects

Kjoller, R.

Publications and source records attributed to Kjoller, R..

3 recordsLinked to original sources

bioRxiv2025

Tree species shape ectomycorrhizal fungal traits and community composition through litter quality and resultant soil properties

Ectomycorrhizal (ECM) fungi are key components of the nitrogen (N) and carbon (C) cycles in temperate and boreal forests soils. However, it is still unclear how differences in soil properties driven by litter quality shape ECM fungal diversity and composition. To test this, we used a unique common garden experiment in Denmark which included three common European tree species, lime, beech, and Norway spruce, each associated with contrasting litter quality from fast-to slow-turnover respectively. We found that soil physicochemical properties varied significantly among tree species, with spruce soils having higher soil organic matter (SOM), phosphorus (P), inorganic N and lower pH, than beech and lime. A total of 1,248 ECM root tips were selected for Sanger sequencing and individually assessed for the presence of hyphae and/or rhizomorphs protruding from the fungal mantle. Sequencing revealed 133 fungal amplicon sequence variants (ASVs), clustered in 86 fungal operational taxonomic units (OTUs), from which 61 corresponded to ECM fungi. Compared to spruce, lime and beech supported a higher ECM fungal richness and diversity in lime and beech compared to spruce. The ECM fungal community composition differed significantly between broadleaved species and spruce, with Russula dominating in lime and beech. Regarding fungal traits, in addition to the direct observations of hyphae and rhizomorphs, species were also scored based on literature for exploration types and hyphae hydrophobicity. Tree species had a specific association with ECM fungal exploration types, with broadleaved species favoring contact and short-distance types and spruce associating with long-distance types. The results suggest that tree species via foliar litter quality have a direct impact on soil properties and indirect to the ECM fungal community, where broadleaved tree species with nutrient-rich and rapid decomposing litter support a more diverse ECM community with limited soil exploration capabilities, while spruce supports an ECM fungal community more adapted to soil exploration.

ecology↗

bioRxiv2021

Treated like dirt: Robust forensic and ecological inferences from soil eDNA after challenging sample storage

Biodiversity of soil microbiota is routinely assessed with environmental DNA-based methods, among which amplification and massive parallel sequencing of marker genes (eDNA metabarcoding) is the most common. Soil microbiota may for example be investigated in relation to biodiversity research or as a tool in forensic investigations. After sampling, the taxonomic composition of soil biotic communities may change. In order to minimize community changes after sampling, it is desirable to reduce biological activity, e.g. by freezing immediately after sampling. However, this may be impossible due to remoteness of study sites or, in forensic cases, where soil has been attached to a questioned item for protracted periods of time. Here we investigated the effect of storage duration and conditions on the assessment of the soil biota with eDNA metabarcoding. We extracted eDNA from freshly collected soil samples and again from the same samples after storage under contrasting temperature conditions. We used five different primer sets targeting bacteria, fungi, protists (cercozoans), general eukaryotes, and plants. For these groups, we quantified differences in richness, evenness and community composition. Subsequently, we tested whether we could correctly infer habitat type and original sample identity after storage using a large reference dataset. We found increased community composition differences with extended storage time and with higher storage temperature. However, for samples stored less than 28 days at a maximum of 20{degrees}C, changes were generally insignificant. Classification models could successfully assign most stored samples to their exact location of origin and correct habitat type even after weeks of storage. Even samples showing larger compositional changes generally retained the original sample as the best match (relative similarity). Our results show that for most biodiversity and forensic applications, storage of samples for days and even several weeks may not be a problem, if storage temperature does not exceed 20{degrees}C. Even after suboptimal storage conditions, significant patterns can be reproduced.

ecology↗

bioRxiv2019

Total RNA-sequencing reveals multi-level microbial community changes and functional responses to wood ash application in agricultural and forest soil

Recycling of wood ash from energy production may counteract soil acidification and return essential nutrients to soils. However, wood ash amendment affects soil physicochemical parameters that control composition and functional expression of the soil microbial community. Here, we applied Total RNA-sequencing to simultaneously assess the impact of wood ash amendment on the active soil microbial communities and the expression of functional genes from all microbial taxa. Wood ash significantly affected the taxonomic (rRNA) as well as functional (mRNA) profiles of both agricultural and forest soil. Increase in pH, electrical conductivity, dissolved organic carbon and phosphate were the most important physicochemical drivers for the observed changes. Wood ash amendment increased the relative abundance of the copiotrophic groups Chitinonophagaceae (Bacteroidetes) and Rhizobiales (Alphaproteobacteria) and resulted in higher expression of genes involved in metabolism and cell growth. Finally, Total RNA-sequencing allowed us to show that some groups of bacterial feeding protozoa increased concomitantly to the enhanced bacterial growth, which shows their pivotal role in the regulation of bacterial abundance in soil.

microbiology↗