Portrait photo of Sandra Jämtgård in a forestPhoto: Andreas Palmén

My group’s research revolves around understanding the mechanisms governing plant nitrogen availability at the root-soil interface. A key tool in our research is the sampling technique microdialysis.
Our main aim is to develop microdialysis as a tool for root simulation, investigating key aspects of root physiology and plant-microbial interactions and how that influence plant nitrogen availability at the root surface, in a root growing in undisturbed soil.

In many ecosystems, nitrogen availability is limiting plant growth. Nitrogen is therefore applied to increase yields. Further insight into the plant perspective of nitrogen availability could lead to identifying ways to increase nitrogen use efficiency and decrease nitrogen pollution in managed environments. Critical in this seems to be the sampling methods used. Microdialysis is an approach for seeing nitrogen availability from a roots perspective.

We use microdialysis for measuring induced diffusive fluxes of foremost nitrogen, simulating what a plant root would experience in the field. An important factor in mirroring plant nitrogen availability at the root surface, particularly for the organic forms, in soil, is that this tool enables sampling with very little disturbance of the soil and that it allows continuous sampling. Due these sampling benefits, this technique has unveiled that in unfertilized soil, plant roots has access to a larger proportion of organic nitrogen than previously detected.

In a recent study, we used microdialysis to simulate root exudation by retrodialysis and its effect on nitrogen availability. Our study revealed that in a short-term perspective, nitrogen availability decreased, rather than increased most likely due to microbial immobilization.

Microdialysis allows repeated sampling, in situ in a small scale. This has led us to develop the application of this technique in additional directions. This includes sampling low molecular weight organic carbon compounds, enzymes and signalling molecules involved in plant-mycorrhiza interactions.

Our close collaboration with the Swedish Metabolomics Centre (SMC) enables our work on organic nitrogen in analysis of amino acids LC-MS (QQQ) and dipeptides and LC-MS (qTOF) quantification of isotopically labelled amino acids and metabolomic screening with GC-MS. This collaboration led to a recent study highlighting how critical the analysis is for evaluating the importance of plant uptake of organic nitrogen.

Close up of two hands setting in a microdialysis device into forest soilsMicrodialysis probe inserted into the soil organic layer in the boreal forest (photo: Sandra Jämtgård)

Read more about Sandra Jämtgård's research

Key publications

  • Buckley S, Brackin R, Näsholm T, Schmidt S, Jämtgård S. 2022. The influence of sucrose on soil nitrogen availability–A root exudate simulation using microdialysis. Geoderma 409, 115645.
  • Svennerstam H, Jämtgård S. 2022. Timing is everything–obtaining accurate measures of plant uptake of amino acids. New Phytologist 234: 311-318.
  • Plett K, Buckley S, Plett J, Anderson I, Lundberg-Felten J, Jämtgård S. 2021. Novel microdialysis technique reveals a dramatic shift in metabolite secretion during the early stages of the interaction between the ectomycorrhizal fungus Pisolithus microcarpus and its host Eucalyptus grandis. Microorganisms 9: 1817.
  • Buckley S, Brackin R, Jämtgård S, Näsholm T, Schmidt S, 2020. Microdialysis in soil environments: Current practice and future perspectives. Soil Biology & Biochemistry 143: 107743.
  • Buckley S, Brackin R, Näsholm T, Schmidt S, Jämtgård S. 2017. Improving in situ recovery of soil nitrogen using the microdialysis technique. Soil Biology & Biochemistry 114:93-103.
  • Ganeteg U, Ahmad I, Jämtgård S, Aguetoni Cambui C, Inselsbacher E, Svennerstam H, Schmidt S and Näsholm T. 2017. Amino acid transporter mutants of Arabidopsis provides evidence that a non-mycorrhizal plant acquires organic nitrogen from agricultural soil. Plant Cell and Environment 40: 413-423.
  • Jämtgård S, Näsholm T and Huss-Danell K. 2010. Nitrogen compounds in soil solutions of agricultural land. Soil Biology & Biochemistry 42: 2325-2330.