How do forest management strategies that aim on improving plant growth influence the fungal community? Andreas Schneider, PhD student in Nathaniel Street´s group at Umeå Plant Science Centre, has contributed to the development of new sequence analysis methods that make it easier to study fungal communities. He will defend his PhD thesis on Wednesday, 1st of June 2022 at Umeå University.
Studying fungal communities in the forest soil is very challenging. The mushrooms seen in the forest in autumn are just made by some of the fungi to spread their spores. The most time of their lifecycle fungi are hidden in the soil or inside of the roots of their host plants. Recently developed advanced sequencing techniques offer many new possibilities and Andreas Schneider and his colleagues used these advances to develop automated bioinformatic tools that allow to study the dynamic and diversity of fungal communities in the soil.
“Many of the methods used to study fungi today are indirect. We take a soil sample, extract DNA from it and see to which species this DNA might belong to,” explains Andreas Schneider. “We used these methods in some of our studies, but one problem is that you do not know if the DNA comes from fungi that are dead or from some that are alive and active. That is why we used and further developed another method that is also indirect but that shows how active the fungi are. The great thing is that this can tell us what the fungi are up to, which genes are being expressed.”
To test their method, the researchers analysed how nitrogen addition affects the fungal community. Swedish forests are usually low in nitrogen and conifer trees compensate for this limitation by establishing the symbiosis with mycorrhizal fungi. The trees deliver carbon to the fungi and receive nitrogen in return. For seedlings on reforestation sites, it is crucial to establish the connection with the fungi to improve their chances to survive.
“Nitrogen addition, especially in high doses, is already known to change the fungal community in the soil quite a lot. Our experiments show that small amounts of organic nitrogen fertilization do not affect the fungal community but can improve the survival and growth rates of seedlings,” says Andreas Schneider. “This was true for seedlings coming from nurseries and also for seeds that were directly placed on the field site. We still need to follow up on the seedling growth rates over a longer period of time and for more different local conditions, but the current results are very promising.”
In a different approach, Andreas Schneider and his colleagues analysed why nitrogen addition inhibits the degradation of lignin in forest soils. Lignin is the component in dead plant material that is decomposed the most slowly by white-rot fungi. The researchers could show that nitrogen addition affects chemical processes in the soil and that this can have a negative impact on the efficiency of white-rot fungi.
They could also confirm that the composition of the fungal community associated with tree roots is changed on sites with high nitrogen fertilization favouring nitrogen tolerant fungi species. This can be caused both by soil chemistry changes and by a reprogramming of the mycorrhizal symbiosis from the side of the host tree.
“We could show that our methods are working and are useful to study dynamic changes in the fungal community”, thinks Andreas Schneider. “The biggest limitation now is the lack of genetic information for most fungal species, but we and many others are working on that. I am sure that in the future, this new knowledge and these methods will help us to evaluate even better how different forest management strategies influence fungal activity and biodiversity.”
About the public defence:
Andreas Schneider, Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, will defend his PhD thesis on Wednesday, 1st of June 2022. Faculty opponent will be Colin Averill, Department of Environmental Systems Science, ETH Zurich, Switzerland. The thesis was supervised by Nathaniel Street. Andreas Schneider was part of the PhD Research School in Forest Genetics, Biotechnology and Breeding and collaborated for his PhD project with Holmen Skog.
Title of the thesis: Perturbance and stimulation - using nitrogen addition and high throughput sequencing to study fungal communities in boreal forests
For more information, please contact:
Umeå Plant Science Centre
Department of Plant Physiology