Plants stand still, while their fungal partners come and go

Plants stand still, while their fungal partners come and go

Top image: Research area by Isdammen. Photo: Sunil Mundra/UNIS

Many plants and fungi cooperate; a plant pays fungi with sugar to function as an extension of its root system. The Arctic environment has extreme seasonality, but little is known about how climatic changes in the Arctic affect the diversity and composition of root-associated fungi. New research show that even if plants are rooted to the spot, their fungal partners change in response to climatic and environmental variation over time.

7 December 2015
Press release from UNIS

UNIS scientists Sunil Mundra and Pernille B. Eidesen together with colleagues from University of Oslo (Norway) and University of Tartu (Estonia) recently published these results in Molecular Ecology.

Fungi represent one of the largest groups of living organisms and play crucial roles in decomposition, symbiotic interactions, and biogeochemical cycling in most terrestrial ecosystems, including the Arctic. These ecosystem services are fundamental not only for primary production, but for the long-term functioning of the Arctic ecosystem.

Poor understanding of patterns
However, the determinants of fungal diversity and seasonal patterns remain poorly understood, especially in the High Arctic. Mere ~2% of all fungal species discovered till date and remaining need to be explored. Additionally, basic knowledge on the habitats and geographical distribution is lacking for even commonly known fungal species.

Many plants and fungi have a symbiotic association called mycorrhiza. In this partnership, a plant pays fungi with sugar to function as an extension of the plants root system, increasing its water and nutrient uptake. The Arctic environment is characterized by extreme seasonality, but little is known about how temporal climatic and environmental changes in the Arctic affect the diversity and composition of root-associated fungi.

As study system, the scientists used one of the most common plants in Svalbard; Alpine bistort (Bistorta vivipara), or “harerug” in Norwegian. This species form a type of plant root-fungi symbiosis called ectomycorrhizal. The research team concludes that seasonality and the underlying climatic variables affect richness and composition of Bistorta vivipara-associated ectomycorrhiza (ECM) and that these changes are inconsistent across years with contrasting climate.

Fungi more complex than plants
They found that the most species rich and dominating ECM fungal genera were Tomentella, Thelephora, Cortinarius, Inocybe, Hebeloma and Cenococcum. In the Arctic, B. vivipara is living at the margin of its climatic and environmental tolerances. The observed dominance and persistence of fungal symbionts with stress tolerating and nutrient mobilizing abilities is probably essential for host-plant survival in nutrient poor arctic conditions.

The present study shows that seasonal patterns of fungi are more complex than those of plants and animals as major groups of fungi display distinct distributional trends.

This research show that even if plants are rooted to the spot, their fungal partners change in response to climatic and environmental variation over time; particularly surprising was the high species richness in winter compared to the growing-season.

This work is part of a larger research project “MicroFun” at UNIS where the overall aim is to better understand what environmental factors shape diversity and distribution of microbial eukaryotes like fungi in high-arctic areas.

This research was funded by ConocoPhillips and Lundin Petroleum through The Northern Area program.

Publication:
Mundra S., Bahram M., Tedersoo L., Kaserusd H., Halvorsen R., and Eidesen PB (2015). Temporal variation of Bistorta vivipara-associated ectomycorrhizal fungal communities in the High-Arctic. Molecular Ecology, DOI: 10.1111/mec.13458. http://onlinelibrary.wiley.com/doi/10.1111/mec.13458/full

Fungi research collage

Study site established at Isdammen (Svalbard) for temporal study. Bistorta vivipara plant root samples were collected over two years in different seasons. (A, B, C) Sampling area overview on May 3, May 21, July 21, 2012, respectively; (D) Four 3 x 3 m permanent plot for sample collection; (E) Eike Müller drilling the soil core in November 2012; (F) Anna, Stuart and Kelsey at operation soil core sampling in April 2013; (G) Holes left after winter core sampling; (H) Bistorta vivipara rhizome with associated roots and developing shoot retrieved from April 2013 soil core, it seems they already started growth in winter under snow.

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