Understanding the mechanisms that maintain the coexistence of plant species is critical to addressing the global biodiversity crisis. Increasing attention has been paid to interactions between plants and soil microbes (plant-soil feedback, PSF), which can not only promote plant coexistence by increasing stabilizing effects but also hinder it by generating competitive fitness differences. However, the predictive power of the PSF has been questioned in recent studies because estimates of microbially mediated coexistence have correlated poorly with the outcomes of plant interactions observed in the field. This discrepancy may be due to the approaches typically used in PSF research, such as measuring PSF effects on a single vital rate or using soil conditioned for a short time period and without considering abiotic contexts. Here, I examined the effects of soil inoculum with different training histories and training environments (with and without added nutrients) on germination, seedling survival, and biomass of four grassland species. I then examined whether predictions of microbially mediated coexistence of four species pairs were sensitive to the vital rate identity, conditioning history, and soil training environment. I found that conspecific inoculum trained for longer had increasingly positive and negative effects on germination and biomass, respectively, although the effects of inoculum history varied across species and training environments. Estimates of microbially mediated outcomes were directly related to the vital rate used: when based on biomass and seedling survival, all four pairs were predicted to coexist, but only two pairs could do so when based on germination due to much reduced or even negative stabilization. Although coexistence predictions were not significantly related to conditioning history (including the effects of both variable conditioning durations and combinations of conditioning species) or nutrient treatments, both factors had a significant effect on stabilization. These results suggest that predictions of microbially mediated coexistence may be biased when based on a single vital rate, such as plant growth. To obtain more realistic and accurate outcome estimates, PSF effects should be integrated across different life stages, considering the temporal and abiotic contexts of these effects specific to a focal study system.

• Klíčová slova
• fitness differences, plant coexistence, plant–soil feedback, soil microbes, soil nutrients, stabilization, temperate grassland, temporal context,
• MeSH
• biomasa MeSH
• klíčení MeSH
• pastviny MeSH
• půda * chemie   MeSH
• půdní mikrobiologie * MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• půda * MeSH

BACKGROUND: Below-ground microbes mediate key ecosystem processes and play a vital role in plant nutrition and health. Understanding the composition of the belowground microbiome is therefore important for maintaining ecosystem stability. The structure of the belowground microbiome is largely determined by individual plants, but it is not clear how far their influence extends and, conversely, what the influence of other plants growing nearby is. RESULTS: To determine the extent to which a focal host plant influences its soil and root microbiome when growing in a diverse community, we sampled the belowground bacterial and fungal communities of three plant species across a primary successional grassland sequence. The magnitude of the host effect on its belowground microbiome varied among microbial groups, soil and root habitats, and successional stages characterized by different levels of diversity of plant neighbours. Soil microbial communities were most strongly structured by sampling site and showed significant spatial patterns that were partially driven by soil chemistry. The influence of focal plant on soil microbiome was low but tended to increase with succession and increasing plant diversity. In contrast, root communities, particularly bacterial, were strongly structured by the focal plant species. Importantly, we also detected a significant effect of neighbouring plant community composition on bacteria and fungi associating with roots of the focal plants. The host influence on root microbiome varied across the successional grassland sequence and was highest in the most diverse site. CONCLUSIONS: Our results show that in a species rich natural grassland, focal plant influence on the belowground microbiome depends on environmental context and is modulated by surrounding plant community. The influence of plant neighbours is particularly pronounced in root communities which may have multiple consequences for plant community productivity and stability, stressing the importance of plant diversity for ecosystem functioning.

• Publikační typ
• časopisecké články MeSH

Phytoremediation of petroleum hydrocarbons in subarctic regions relies on the successful establishment of plants that stimulate petroleum-degrading microorganisms, which can be challenging due to the extreme climate, limited nutrients, and difficulties in maintaining sites in remote locations. A long-term phytoremediation experiment was initiated in Alaska in 1995 with the introduction of grasses and/or fertilizer to petroleum hydrocarbon (PHC)-contaminated soils that were subsequently left unmanaged. In 2011, the PHC concentrations were below detection limits in all soils tested and the originally planted grasses had been replaced by volunteer plant species that had colonized the site. Here, we sought to understand how the original treatments influenced the structure of prokaryotic communities associated with plant species that colonized the soils and to assess the interactions between the rhizospheric and endophytic communities of the colonizing vegetation 20 years after the experiment was established. Metataxonomic analysis performed using 16S rRNA gene sequencing revealed that the original type of contaminated soil and phytoremediation strategy influenced the structure of both rhizospheric and endophytic communities of colonizing plants, even 20 years after the treatments were applied and following the disappearance of the originally planted grasses. Our findings demonstrate that the choice of initial phytoremediation strategy drove the succession of microorganisms associated with the colonizing vegetation. The outcome of this study provides new insight into the establishment of plant-associated microbial communities during secondary succession of subarctic areas previously contaminated by PHCs and indicates that the strategies for restoring these ecosystems influence the plant-associated microbiota in the long term. IMPORTANCE Subarctic ecosystems provide key services to local communities, yet they are threatened by pollution caused by spills and disposal of petroleum waste. Finding solutions for the remediation and restoration of subarctic soils is valuable for reasons related to human and ecosystem health, as well as environmental justice. This study provides novel insight into the long-term succession of soil and plant-associated microbiota in subarctic soils that had been historically contaminated with different sources of PHCs and subjected to distinct phytoremediation strategies. We provide evidence that even after the successful removal of PHCs and the occurrence of secondary succession, the fingerprint of the original source of contamination and the initial choice of remediation strategy can be detected as a microbial legacy in the rhizosphere, roots, and shoots of volunteer vegetation even 2 decades after the contamination had occurred. Such information needs to be borne in mind when designing and applying restoration approaches for PHC-contaminated soils in subarctic ecosystems.

• Klíčová slova
• bacterial communities, endophyte, petroleum hydrocarbons, phytoremediation, rhizosphere, rhizosphere-inhabiting microbes, secondary succession, subarctic,
• Publikační typ
• časopisecké články MeSH

The aim of this study was to compare plant-soil interactions in the native range of two congeneric European species differing in their invasive success in the world: a globally invasive Cirsium vulgare and non-invasive C. oleraceum. We assessed changes in soil nutrients and soil biota following soil conditioning by each species and compared performance of plants grown in self-conditioned and unconditioned soil, from which all, some or no biota was excluded. The invasive species depleted more nutrients than the non-invasive species and coped better with altered nutrient levels. The invasive species had higher seedling establishment which benefited from the presence of unconditioned biota transferred by soil filtrate. Biomass of both species increased in soil with self-conditioned soil filtrate and decreased in soil with self-conditioned whole-soil inoculum compared to unconditioned filtrate and inoculum. However, the increase was smaller and the decrease greater for the invasive species. The invasive species allocated less biomass to roots when associated with harmful biota, reducing negative effects of the biota on its performance. The results show that in the native range the invasive species is more limited by self-conditioned pathogens and benefits more from unconditioned mutualists and thus may benefit more from loss of effectively specialized soil biota in a secondary range. Our study highlights the utility of detailed plant-soil feedback research in species native range for understanding factors regulating species performance in their native range and pinpointing the types of biota involved in their regulation.

• Klíčová slova
• Arbuscular mycorrhizal fungi (AMF), Enemy release hypothesis, Mycorrhizal inoculation potential (MIP), Phospholipid/neutral fatty acid analysis (PLFA/NLFA), Plant invasiveness, Structural equation modelling,
• MeSH
• kořeny rostlin MeSH
• mykorhiza * fyziologie   MeSH
• půda MeSH
• půdní mikrobiologie MeSH
• rostliny MeSH
• zavlečené druhy MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• půda MeSH