Sirvi Autor "Davison, John" järgi

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Contrast in Mycorrhizal Associations Leads to Divergent Rhizosphere Metabolomes and Plant–Soil Feedback Among Grassland Species
(2026-02) Semchenko, Marina; Pétriacq, Pierre; Prigent, Sylvain; Saar, Sirgi; Horn, Greete; Davison, John; Koorem, Kadri; Moora, Mari; Zobel, Kristjan
Species-specific feedback between plants and soil microbial communities is an important driver of vegetation dynamics. Arbuscular mycorrhizal (AM) fungi colonise most terrestrial plants but are not expected to generate specific feedbacks due to low host specificity. We tested whether variation in mycorrhizal associations and associated rhizosphere metabolomes among co-existing temperate grassland species leads to species-specific plant–soil feedback. More mycorrhizal plant species showed more divergent plant–soil feedback: they experienced reduced growth and mycorrhizal colonisation in soils originating from weakly mycorrhizal species, but feedback became neutral in soil from species with similar mycorrhizal strategies. The species with the most self-promoting soil feedback was characterised by strong metabolome shifts related to stress and immune responses following soil inoculum manipulation, while the metabolomes of species with more negative feedback were unresponsive. This study demonstrates that AM fungi can generate species-specific plant–soil feedback, which can be predicted from plant mycorrhizal strategies and rhizosphere chemistry.
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Phenotypic plasticity masks evolutionary change in grasslandplant traits in response to land use abandonment
(2026-01) Tõnisson, Anastasia; Eck, Jenalle; Jing, Yuying; Kängsep, Piia; Laaspere, Lauri; Wu, Jianlu; Puura, Laura; Torsus, Mari; Koorem, Kadri; Moora, Mari; Sepp, Siim-Kaarel; Davison, John; Semchenko, Marina
Traditionally managed grasslands are among the most biodiverse habitats in Europe, but are threatened by land use abandonment. While the negative impacts of grazing and mowing cessation on species richness are well documented, little is known about potential evolutionary changes within species. Yet, intraspecific functional diversity is critical for successful grassland restoration and ensuring adaptive potential to future climate change. To disentangle the heritable and non-heritable components of population-level response to land use change in semi-natural grasslands, we examined 22 populations of a common grass, Briza media, from grazed sites and sites where grazing was abandoned, with resulting tree and shrub encroachment. We measured a range of traits under field conditions and following clonal propagation under common garden conditions. Field surveys revealed that abandonment resulted in litter accumulation, greater shading by woody and herbaceous vegetation, and lower temperature and moisture fluctuations compared with grazed sites. Plants responded to conditions at abandoned sites with phenotypic plasticity in traits that enhanced competitive ability for light (greater height and specific leaf area) but reduced tissue protection against stress (lower dry matter content). However, when the same genotypes were measured after clonal propagation in common conditions, counter-gradient variation was apparent, with heritable shifts towards increased tissue protection in populations from abandoned sites. When measured under field conditions, trait diversity was higher in sites with higher levels of shading and productive sites with higher variation in light conditions. However, high heritable trait diversity was instead characteristic of grazed sites with high densities of flowering B. media individuals. Synthesis. These findings demonstrate that land use change can cause evolutionary shifts and changes in heritable trait diversity that are masked in the field by phenotypic plasticity. Hence, the assessment of functional trait variation based on field observations is not a reliable way to assess the genetic variation essential for population adaptive potential.
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Plant mycorrhizal status indicates partner selectivity in arbuscular mycorrhizal interaction networks
(2024) Koorem, Kadri; Sepp, Siim-Kaarel; Bueno, C. Guillermo; Davison, John; Liu, Siqiao; Meng, Yiming; Semchenko, Marina; Vasar, Martti; Zobel, Martin; Moora, Mari
Mycorrhizal symbiosis, specifically arbuscular mycorrhiza, is one of Earth's oldest and most widespread symbiosis. Existing evidence suggests that plant species differ in their associations with mycorrhizal partners, with different species reported to be always (obligately mycorrhizal, OM), sometimes (facultatively mycorrhizal, FM) or never (non-mycorrhizal, NM) associating with arbuscular mycorrhizal (AM) fungi and this plant reliance on AM fungi is called plant mycorrhizal status. However, very little is known about how host plant mycorrhizal status shapes the network topology of interacting AM fungi. Here, we use a standardized sampling scheme to test whether plant species with different mycorrhizal statuses differ in mean AM fungal hyphal colonization and various indices of the AM fungal networks such as nestedness rank and resource range. We collected the roots and rhizosphere soil of 19 plant species representing five families. Each plant species was sampled from three distinct habitats. We determined AM fungal colonization in the roots and AM fungal community composition in roots and rhizosphere soil using molecular methods. We found that previously reported NM plant species had lower mean AM fungal colonization than FM plant species, but no differences were found between FM and OM plant species. Network analyses indicated that AM fungal communities in the roots of FM plant species had higher nestedness rank and resource range than networks associated with OM plant species, suggesting that OM plant species are more generalist regarding partner selection and interact with a wider range of fungal partners. Our results suggest that plant mycorrhizal status conveys useful information about the characteristics of AM fungal interaction networks, revealing that plant species consistently associated with AM fungi are less selective towards their fungal partners.
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Symbiont plasticity as a driver of plant success
(2024) Zobel, Martin; Koorem, Kadri; Moora, Mari; Semchenko, Marina; Davison, John
We discuss which plant species are likely to become winners, that is achieve the highest global abundance, in changing landscapes, and whether plant-associated microbes play a determining role. Reduction and fragmentation of natural habitats in historic landscapes have led to the emergence of patchy, hybrid landscapes, and novel landscapes where anthropogenic ecosystems prevail. In patchy landscapes, species with broad niches are favoured. Plasticity in the degree of association with symbiotic microbes may contribute to broader plant niches and optimization of symbiosis costs and benefits, by downregulating symbiosis when it is unnecessary and upregulating it when it is beneficial. Plasticity can also be expressed as the switch from one type of mutualism to another, for example from nutritive to defensive mutualism with increasing soil fertility and the associated increase in parasite load. Upon dispersal, wide mutualistic partner receptivity is another facet of symbiont plasticity that becomes beneficial, because plants are not limited by the availability of specialist partners when arriving at new locations. Thus, under conditions of global change, symbiont plasticity allows plants to optimize the activity of mutualistic relationships, potentially allowing them to become winners by maximizing geographic occupancy and local abundance.