Department of Mycorrhizal Symbioses

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We study mutualistic mycorrhizal associations between specific soil fungi and plant roots, namely arbuscular mycorrhiza, ectomycorrhiza and ericoid mycorrhiza. We also focus on interactions between various types of mycorrhiza and their interactions with soil saprophytic fungi. Find out more at https://www.ibot.cas.cz/mykosym/.

 

Research topics

  • Diversity, biogeography and community ecology of root-associated fungi
  • Relationship between the composition and symbiotic functioning of mycorrhizal fungal communities
  • Functioning of arbuscular mycorrhiza under drought
  • Fungal symbioses of seagrasses
  • Microbial inoculants in the development of specific cultivation methodologies

 

Selected recent results

1/ Alien ectomycorrhizal plants differ in their ability to interact with co-introduced and native ectomycorrhizal fungi in novel sites

Establishment of alien trees outside their native range can be constrained by the absence of suitable fungal partners. Our metastudy shows that alien conifers rely upon association with co-introduced fungi from their native range, while alien eucalypts often form novel associations with fungi native to the region of introduction. Successful establishment of distinct groups of exotic trees can vary depending on their ability to associate with local fungi.

  • Vlk L., Tedersoo L., Antl T., Větrovský T., Abarenkov K., Pergl J., Albrechtová J., Vosátka M., Baldrian P., Pyšek P. & Kohout P. (2020). Alien ectomycorrhizal plants differ in their ability to interact with co-introduced and native ectomycorrhizal fungi in novel sites. The ISME Journal, 14(9), 2336–2346. doi: 10.1038/s41396-020-0692-5

Global distribution of analysed ectomycorrhizal (EM) fungal communities

Global distribution of analysed ectomycorrhizal (EM) fungal communities (pie charts) associated with (a) alien conifers and (b) alien eucalypts. Colors of the pie charts indicate share of the three strategies that alien EM plants adapted to establish in new areas: interaction with co-introduced EM fungi from their native range (red), association with EM fungi which naturally occur in both native as well as introduced regions of the host plant (green), and establishment of novel associations with native EM fungal species (yellow). Native distribution ranges of Pinaceae and eucalypts are highlighted by green colour.

 

2/ Early successional ectomycorrhizal fungi are more likely to naturalize outside their native range than other ectomycorrhizal fungi

Ectomycorrhizal (EM) fungi are the key symbionts of numerous species of woody plants around the globe. Some have been co-introduced to a number of ecosystems along with their plant hosts. In this metastudy we investigated EM fungal communities associated with alien trees worldwide to assess the numbers and ecology of introduced EM fungi worldwide. Overall, we provide evidence that early succesional EM fungal species are more likely to naturalize in new areas on global scale.

  • Vlk L., Tedersoo L., Antl T., Větrovský T., Abarenkov K., Pergl J., Albrechtová J., Vosátka M., Baldrian P., Pyšek P. & Kohout P. (2020). Early successional ectomycorrhizal fungi are more likely to naturalize outside their native range than other ectomycorrhizal fungi. New Phytologist, 227(5), 1289-1293. doi: 10.1111/nph.16557

 

3/ Interactions of saprotrophic and root symbiotic fungi control the transformation of humic substances and phosphorus in Norway spruce needle litter

 Our results show that interactions of fungi from different ecological guilds (saprotrophic, mycorrhizal, endophytic) influence the flow of phosphorus in decaying plant litter and the transformation of the soil organic matter itself. Mineralization of plant litter promoted by saprobes was slowed down by mycorrhizal but not by endophytic fungi. The tested fungi did not affect the amount of produced humic substances but changed their chemical characteristics. Dark pigmented fungi increased the relative proportion of carboxylic moieties in the humic substances probably via the production and incorporation of melanins. Effect of fungal interactions on the  humification and phosphorus flow was not uniform over the tested species demonstrating importance of species identity in the transformation process. Fungal root endophytes can significantly contribute to litter transformation along with mycorrhizal and saprotrophic fungi.

 

4/ Taxonomic placement and description of Posidoniomyces atricolor gen. et sp. nov., the dominant root symbiont of the Mediterranean seagrass Posidonia oceanica

It is assumed that seagrasses do not form mycorrhizae or any other specific root-fungus symbioses. The dominant Mediterranean seagrass Posidonia oceanica is an exception – recently, our team discovered that its roots host a unique symbiosis formed by a hitherto undescribed pleosporalean fungus, resembling the ubiquitous terrestrial root symbiosis with the so-called Dark Septate Endophytes. Thus, the aims of the present study were 1/ to investigate the distribution of the symbiosis, 2/ to describe the total fungal diversity in P. oceanica roots and 3/ to place taxonomically and describe the dominant pleosporalean symbiont. The symbiosis was present at all 32 investigated localities across the NW Mediterranean. At the same time, the total root fungal diversity was very low and dominated by the pleosporalean fungus. A multigene phylogenetic analysis confirmed that the fungus represents a new monotypic genus in the recently established Aigialaceae family and it was described as Posidoniomyces atricolor. The fungus is not known from any other hosts or environments and represents the only biotrophic representative in the Aigialaceae.

  • Vohník M., Borovec O., Kolaříková Z, Sudová R, Réblová M. (2019) Extensive sampling and high-throughput sequencing reveal Posidoniomyces atricolor gen. et sp. nov. (Aigialaceae, Pleosporales) as the dominant root mycobiont of the dominant Mediterranean seagrass Posidonia oceanica. MycoKeys 55: 59–86. doi: 10.3897/mycokeys.55.35682

Characteristic root colonization pattern in the seagrass Posidonia oceanica

Posidoniomyces atricolor – characteristic root colonization pattern in the seagrass Posidonia oceanica and morphology of its colonies during isolation on nutrient media. a. In vivo colonization on the root surface (arrows) and in the hypodermis (asterisks) of P. oceanica; b. Dark septate endophytic colonization on the root surface; c. Germinating microsclerotia stained with trypan blue (arrows); d. Compact colony developed from microsclerotia (arrow); e. Surface-sterilized root segments yielding P. atricolor compact colonies (black arrows), sometimes with substrate mycelium (white arrows); f. Compact colonial morphotype of P. atricolor; g. Mycelial colonial morphotype of P. atricolor; h. Mycelial morphotype developing from microsclerotia (arrows) in transversal section. Scale bars: a, b = 20 μm, c = 50 μm, d = 100 μm, f, h = 200 μm, g = 500 μm.

 

5/ Survival and long-term infectivity of arbuscular mycorrhizal fungi in peat-based substrates stored under different temperature regimes

The study tested long-term infectivity of arbuscular mycorrhizal fungi (AMF) when introduced to a peat-based horticultural substrate and stored in five different temperature regimes (constant temperatures of −20, 5 or 20 °C) and two outdoor regimes simulating actual practice (shade and direct sunlight). Eight AMF inocula were tested, including 5 monocultures applied as 4% (v) of the substrate or their mixture in 1%, 4% and 8% (v) doses. Their infectivity was monitored for 56 weeks at 8-week intervals. In general, infectivity significantly decreased with time, but in three regimes including periods of cold (5 °C, shade and sunlight), cold stratification probably broke spore dormancy and led to temporal stimul­ation of AMF infectivity. Two AMF were found most resistant among the tested AMF. Except for storage at 5 °C, where a wider AMF spectrum maintained sufficient long-term viability, infectivity became very low after one year. Temperature fluctuations in direct sunlight were less negative than expected, whereas infectivity decline was surprisingly strong also in mild storage conditions (20 °C). Higher inoculum dose lengthened AMF infectivity. We ascribe the general decline of infectivity to unfavourable properties inherent to peat.

  • Püschel D., Kolaříková Z., Šmilauer P. & Rydlová J. (2019). Survival and long-term infectivity of arbuscular mycorrhizal fungi in peat-based substrates stored under different temperature regimes. Applied Soil Ecology 140: 98-107. doi: 10.1016/j.apsoil.2019.04.020

 

6/ Abiotic conditions determine the functioning of mycorrhizal symbiosis independently of the community composition of the fungal symbionts

The experimental study addressed the relationship between abiotic conditions, the composition of mycorrhizal fungal communities and the host plant’s benefit from mycorrhiza. While the abiotic conditions fundamentally influenced the plant benefit, the fungal community composition was determined by the fungal species’ traits. The functioning of mycorrhiza on the continuum between mutualism and parasitism had only a small and transient effect on the fungal community.

  • Voříšková A., Jansa J., Püschel D., Vosátka M., Šmilauer P. & Janoušková M. (2019). Abiotic contexts consistently influence mycorrhiza functioning independently of the composition of synthetic arbuscular mycorrhizal fungal communities. Mycorrhiza 29: 127-139. doi: 10.1007/s00572-018-00878-8

Greenhouse experiment focusing on the relationship of abiotic conditions, the composition of mycorrhizal fungal communities and the functioning of mycorrhizal symbiosis.

Greenhouse experiment focusing on the relationship of abiotic conditions, the composition of mycorrhizal fungal communities and the functioning of mycorrhizal symbiosis.