Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Competition and predation as possible causes of bacterial rarity
    Kurm, Viola ; Putten, Wim H. van der; Weidner, Simone ; Geisen, Stefan ; Snoek, Basten L. ; Bakx, Tanja ; Gera Hol, Wilhelmina H. - \ 2019
    Environmental Microbiology 21 (2019)4. - ISSN 1462-2912 - p. 1356 - 1368.

    We assembled communities of bacteria and exposed them to different nutrient concentrations with or without predation by protists. Taxa that were rare in the field were less abundant at low nutrient concentrations than common taxa, independent of predation. However, some taxa that were rare in the field became highly abundant in the assembled communities, especially under ample nutrient availability. This high abundance points at a possible competitive advantage of some rare bacterial taxa under nutrient-rich conditions. In contrast, the abundance of most rare bacterial taxa decreased at low resource availability. Since low resource availability will be the prevailing situation in most soils, our data suggests that under those conditions poor competitiveness for limiting resources may contribute to bacterial rarity. Interestingly, taxa that were rare in the field and most successful under predator-free conditions in the lab also tended to be more reduced by predation than common taxa. This suggests that predation contributes to rarity of bacterial taxa in the field. We further discuss whether there may be a trade-off between competitiveness and predation resistance. The substantial variability among taxa in their responses to competition and predation suggests that other factors, for example abiotic conditions and dispersal ability, also influence the local abundance of soil bacteria.

    Where less may be more: how the rare biosphere pulls ecosystems strings
    Jousset, A. ; Bienhold, C. ; Chatzinotas, A. ; Gallien, L. ; Gobet, A. ; Kurm, V. ; Küsel, K. ; Rillig, M.C. ; Rivett, D.W. ; Salles, J.F. ; Heijden, M.G.A. van der; Youssef, N.H. ; Zhang, X.W. ; Wei, Z. ; Hol, W.H.G. - \ 2017
    ISME Journal 11 (2017)4. - ISSN 1751-7362 - p. 853 - 862.
    Rare species are increasingly recognized as crucial, yet vulnerable components of Earth’s ecosystems. This is also true for microbial communities, which are typically composed of a high number of relatively rare species. Recent studies have demonstrated that rare species can have an over-proportional role in biogeochemical cycles and may be a hidden driver of microbiome function. In this review, we provide an ecological overview of the rare microbial biosphere, including causes of rarity and the impacts of rare species on ecosystem functioning. We discuss how rare species can have a preponderant role for local biodiversity and species turnover with rarity potentially bound to phylogenetically conserved features. Rare microbes may therefore be overlooked keystone species regulating the functioning of host-associated, terrestrial and aquatic environments. We conclude this review with recommendations to guide scientists interested in investigating this rapidly emerging research area.
    Low abundant soil bacteria can be metabolically versatile and fast growing
    Kurm, V. ; Putten, W.H. van der; Boer, W. de; Naus-Wiezer, Suzanne ; Hol, W.H.G. - \ 2017
    Ecology 98 (2017)2. - ISSN 0012-9658 - p. 555 - 564.
    The abundance of species is assumed to depend on their life history traits, such as growth rate and resource specialization. However, this assumption has not been tested for bacteria. Here we investigate how abundance of soil bacteria relates to slow growth and substrate specialization (oligotrophy) versus fast growth and substrate generalization (copiotrophy). We collected 47 saprotrophic soil bacterial isolates of differing abundances and measured their growth rate and the ability to use a variety of single carbon sources. Opposite to our expectation, there was no relationship between abundance in soil and the measured growth rate or substrate utilization profile (SUP).However, isolates with lower growth rates used fewer substrates than faster growing ones supporting the assumption that growth rate may relate to substrate specialization. Interestingly, growth rate and SUP were correlated with phylogeny, rather than with abundancein soil. Most markedly, Gammaproteobacteria on average grew significantly faster and were able to use more substrates than other bacterial classes, whereas Alphaproteobacteria were growing relatively slowly and used fewer substrates. This finding suggests that growth and substrate utilization are phylogenetically deeply conserved. We conclude that growth rate and substrate utilization of soil bacteria are not general determinants of their abundance. Future studies on explaining bacterial abundance need to determine how other factors, such as competition, predation and abiotic factors may contribute to rarity or abundance in soil bacteria.
    Does bacterial diversity matter in plant insect interactions?
    Kurm, V. ; Putten, W.H. van der; Hol, W.H.G. - \ 2016
    The potential of hyperspectral patterns of winter wheat to detect changes in soil microbial community composition
    Almeida De Carvalho, Sabrina ; Putten, Wim H. van der; Hol, W.H.G. - \ 2016
    Frontiers in Plant Science 7 (2016)June2016. - ISSN 1664-462X
    Biodiversity - Land use - Monitoring - Serial dilution - Species loss - Triticum aestivum L

    Reliable information on soil status and crop health is crucial for detecting and mitigating disasters like pollution or minimizing impact from soil-borne diseases. While infestation with an aggressive soil pathogen can be detected via reflected light spectra, it is unknown to what extent hyperspectral reflectance could be used to detect overall changes in soil biodiversity. We tested the hypotheses that spectra can be used to (1) separate plants growing with microbial communities from different farms; (2) to separate plants growing in different microbial communities due to different land use; and (3) separate plants according to microbial species loss. We measured hyperspectral reflectance patterns of winter wheat plants growing in sterilized soils inoculated with microbial suspensions under controlled conditions. Microbial communities varied due to geographical distance, land use and microbial species loss caused by serial dilution. After 3 months of growth in the presence of microbes from the two different farms plant hyperspectral reflectance patterns differed significantly from each other, while within farms the effects of land use via microbes on plant reflectance spectra were weak. Species loss via dilution on the other hand affected a number of spectral indices for some of the soils. Spectral reflectance can be indicative of differences in microbial communities, with the Renormalized Difference Vegetation Index the most common responding index. Also, a positive correlation was found between the Normalized Difference Vegetation Index and the bacterial species richness, which suggests that plants perform better with higher microbial diversity. There is considerable variation between the soil origins and currently it is not possible yet to make sufficient reliable predictions about the soil microbial community based on the spectral reflectance. We conclude that measuring plant hyperspectral reflectance has potential for detecting changes in microbial communities yet due to its sensitivity high replication is necessary and a strict sampling design to exclude other ‘noise’ factors.

    Context dependency and saturating effects of loss of rare soil microbes on plant productivity
    Hol, W.H.G. ; Boer, W. de; Hollander, M. de; Kuramae, E.E. ; Meisner, A. ; Putten, W.H. van der - \ 2015
    Frontiers in Plant Science 6 (2015). - ISSN 1664-462X - 10 p.
    Land use intensification is associated with loss of biodiversity and altered ecosystem functioning. Until now most studies on the relationship between biodiversity and ecosystem functioning focused on random loss of species, while loss of rare species that usually are the first to disappear received less attention. Here we test if the effect of rare microbial species loss on plant productivity depends on the origin of the microbial soil community. Soils were sampled from three land use types at two farms. Microbial communities with increasing loss of rare species were created by inoculating sterilized soils with serially diluted soil suspensions. After 8 months of incubation, the effects of the different soil communities on abiotic soil properties, soil processes, microbial community composition, and plant productivity was measured. Dilution treatments resulted in increasing species loss, which was in relation to abundance of bacteria in the original field soil, without affecting most of the other soil parameters and processes. Microbial species loss affected plant biomass positively, negatively or not at all, depending on soil origin, but not on land use history. Even within fields the effects of dilution on plant biomass varied between replicates, suggesting heterogeneity in microbial community composition. The effects of medium and severe species loss on plant biomass were similar, pointing toward a saturating effect of species loss. We conclude that changes in the composition of the soil microbial community, including rare species loss, can affect plant productivity, depending on the composition of the initial microbial community. Future work on the relation between function and species loss effects should address this variation by including multiple sampling origins.
    Intensive agriculture reduces soil biodiversity across Europe
    Tsiafouli, M.A. ; Thébault, E. ; Sgardelis, S. ; Ruiter, P.C. de; Putten, W.H. van der; Birkhofer, K. ; Hemerik, L. ; Vries, F.T. de; Bardgett, R.D. ; Brady, M. ; Bjornlund, L. ; Bracht Jörgensen, H. ; Christensen, S. ; Herfelt, T. D'; Hotes, S. ; Hol, W.H.G. ; Frouz, J. ; Liiri, M. ; Mortimer, S.R. ; Setälä, H. ; Stary, J. ; Tzanopoulos, J. ; Uteseny, C. ; Wolters, V. ; Hedlund, K. - \ 2015
    Global Change Biology 21 (2015)2. - ISSN 1354-1013 - p. 973 - 985.
    food-web structure - land-use intensity - taxonomic distinctness - community structure - phylogenetic diversity - arthropod communities - temporal variability - 7-year period - ecosystem - management
    Soil biodiversity plays a key role in regulating the processes that underpin the delivery of ecosystem goods and services in terrestrial ecosystems. Agricultural intensification is known to change the diversity of individual groups of soil biota, but less is known about how intensification affects biodiversity of the soil food web as a whole, and whether or not these effects may be generalized across regions. We examined biodiversity in soil food webs from grasslands, extensive, and intensive rotations in four agricultural regions across Europe: in Sweden, the UK, the Czech Republic and Greece. Effects of land-use intensity were quantified based on structure and diversity among functional groups in the soil food web, as well as on community-weighted mean body mass of soil fauna. We also elucidate land-use intensity effects on diversity of taxonomic units within taxonomic groups of soil fauna. We found that between regions soil food web diversity measures were variable, but that increasing land-use intensity caused highly consistent responses. In particular, land-use intensification reduced the complexity in the soil food webs, as well as the community-weighted mean body mass of soil fauna. In all regions across Europe, species richness of earthworms, Collembolans, and oribatid mites was negatively affected by increased land-use intensity. The taxonomic distinctness, which is a measure of taxonomic relatedness of species in a community that is independent of species richness, was also reduced by land-use intensification. We conclude that intensive agriculture reduces soil biodiversity, making soil food webs less diverse and composed of smaller bodied organisms. Land-use intensification results in fewer functional groups of soil biota with fewer and taxonomically more closely related species. We discuss how these changes in soil biodiversity due to land-use intensification may threaten the functioning of soil in agricultural production systems.
    The majority of minors: on the identity and function of rare soil bacteria
    Kurm, V. ; Putten, W.H. van der; Hol, W.H.G. - \ 2014
    In: Proceedings of the First Global Soil Biodiversity Conference. - - p. 1.202 - 1.202.
    Most bacterial taxa in soil are low abundant or rare. Usually, rare species are not expected to contribute substantially to ecosystem functioning, however, recent studies suggest that rare bacteria can play a crucial role in soil, for example by possessing distinct traits and acting as keystone species in biogeochemical cycles, by providing an insurance function under changing environmental conditions, or through interactions with other organisms such as plants and plant enemies. Our aim is to identify rare bacterial taxa in soil and investigate their contribution to ecosystem functioning. We use a number of approaches: First we identify bacterial taxa that are constantly rare or exhibit fluctuating abundances by mining sequence databases. Cultivation-based approaches employing flow cell sorting and nutrient-poor media will be used to investigate specific characteristics of permanently rare bacteria, such as cell size and growth rate and the ability to degrade certain substrates. Then, we test their putative role in the insurance of ecosystem functions by monitoring the abundance of selected rare taxa using qPCR under disturbance regimes such as are likely to occur under human influence. Finally we will assess the effects of the loss of rare bacteria on plant biomass production and plant community evenness. Ultimately changes in the induction of systemic plant defences as the result of loss of rare bacterial taxa will be investigated as one mechanism by which rare bacteria might affect plant performance. The combination of approaches will enable us to determine the roles of a selection of rare bacterial taxa in ecosystems. We will test which factors may be influenced by rare taxa: the possession of distinct traits, insuring ecosystem functions under environmental change or affecting plant defences. This approach will enable us to predict consequences of losing rare soil bacteria from ecosystems.
    Plant–soil feedbacks of exotic plant species across life forms: a meta-analysis
    Meisner, A. ; Hol, W.H.G. ; Boer, W. de; Krumins, J.A. ; Wardle, D.A. ; Putten, W.H. van der - \ 2014
    Biological Invasions 16 (2014)12. - ISSN 1387-3547 - p. 2551 - 2561.
    serpentine grassland - invasive plants - native range - biota - communities - pathogens - traits - ecosystems - contribute - dependence
    Invasive exotic plant species effects on soil biota and processes in their new range can promote or counteract invasions via changed plant–soil feedback interactions to themselves or to native plant species. Recent meta-analyses reveale that soil influenced by native and exotic plant species is affecting growth and performance of natives more strongly than exotics. However, the question is how uniform these responses are across contrasting life forms. Here, we test the hypothesis that life form matters for effects on soil and plant–soil feedback. In a meta-analysis we show that exotics enhanced C cycling, numbers of meso-invertebrates and nematodes, while having variable effects on other soil biota and processes. Plant effects on soil biota and processes were not dependent on life form, but patterns in feedback effects of natives and exotics were dependent on life form. Native grasses and forbs caused changes in soil that subsequently negatively affected their biomass, whereas native trees caused changes in soil that subsequently positively affected their biomass. Most exotics had neutral feedback effects, although exotic forbs had positive feedback effects. Effects of exotics on natives differed among plant life forms. Native trees were inhibited in soils conditioned by exotics, whereas native grasses were positively influenced in soil conditioned by exotics. We conclude that plant life form matters when comparing plant–soil feedback effects both within and between natives and exotics. We propose that impact analyses of exotic plant species on the performance of native plant species can be improved by comparing responses within plant life form.
    Heterodera schachtii nematodes interfere with aphid-plant relations on Brassica oleracea
    Hol, W.H.G. ; Boer, W. de; Termorshuizen, A.J. ; Meyer, K.M. ; Schneider, J.H.M. ; Putten, W.H. van der; Dam, N.M. - \ 2013
    Journal of Chemical Ecology 39 (2013)9. - ISSN 0098-0331 - p. 1193 - 1203.
    multitrophic interactions - brevicoryne-brassicae - myzus-persicae - herbivore interactions - mediated interactions - indole glucosinolate - shoot herbivores - soybean aphid - jasmonic acid - amino-acids
    Aboveground and belowground herbivore species modify plant defense responses differently. Simultaneous attack can lead to non-additive effects on primary and secondary metabolite composition in roots and shoots. We previously found that aphid (Brevicoryne brassicae) population growth on Brassica oleracea was reduced on plants that were infested with nematodes (Heterodera schachtii) prior (4 weeks) to aphid infestation. Here, we examined how infection with root-feeding nematodes affected primary and secondary metabolites in the host plant and whether this could explain the increase in aphid doubling time from 3.8 to 6.7 days. We hypothesized that the effects of herbivores on plant metabolites would depend on the presence of the other herbivore and that nematode-induced changes in primary metabolites would correlate with reduced aphid performance. Total glucosinolate concentration in the leaves was not affected by nematode presence, but the composition of glucosinolates shifted, as gluconapin concentrations were reduced, while gluconapoleiferin concentrations increased in plants exposed to nematodes. Aphid presence increased 4-methoxyglucobrassicin concentrations in leaves, which correlated positively with the number of aphids per plant. Nematodes decreased amino acid and sugar concentrations in the phloem. Aphid population doubling time correlated negatively with amino acids and glucosinolate levels in leaves, whereas these correlations were non-significant when nematodes were present. In conclusion, the effects of an herbivore on plant metabolites were independent of the presence of another herbivore. Nematode presence reduced aphid population growth and disturbed feeding relations between plants and aphids.
    Competition increases sensitivity of wheat (Triticum aestivum) to biotic plant-soil feedback
    Hol, W.H.G. ; Boer, W. de; Hooven, F. ten; Putten, W.H. van der - \ 2013
    PLoS ONE 8 (2013)6. - ISSN 1932-6203
    community structure - grassland - ecology - ecosystems - diversity - pathogens - diseases - fungi
    Plant-soil feedback (PSF) and plant competition play an important role in structuring vegetation composition, but their interaction remains unclear. Recent studies suggest that competing plants could dilute pathogenic effects, whereas the standing view is that competition may increase the sensitivity of the focal plant to PSF. In agro-ecosystems each of these two options would yield contrasting outcomes: reduced versus enhanced effects of weeds on crop biomass production. To test the effect of competition on sensitivity to PSF, we grew Triticum aestivum (Common wheat) with and without competition from a weed community composed of Vicia villosa, Chenopodium album and Myosotis arvensis. Plants were grown in sterilized soil, with or without living field inoculum from 4 farms in the UK. In the conditioning phase, field inocula had both positive and negative effects on T. aestivum shoot biomass, depending on farm. In the feedback phase the differences between shoot biomass in T. aestivum monoculture on non-inoculated and inoculated soils had mostly disappeared. However, T. aestivum plants growing in mixtures in the feedback phase were larger on non-inoculated soil than on inoculated soil. Hence, T. aestivum was more sensitive to competition when the field soil biota was present. This was supported by the statistically significant negative correlation between shoot biomass of weeds and T. aestivum, which was absent on sterilized soil. In conclusion, competition in cereal crop-weed systems appears to increase cereal crop sensitivity to soil biota.
    Soil food web properties explain ecosystem services across European land use systems
    Vries, F.T. de; Thebault, E.M.C. ; Liiri, M. ; Birkhofer, K. ; Tsiafouli, M. ; Bjornlund, L. ; Jorgensen, H.B. ; Brady, M.V. ; Christensen, S. ; Ruiter, P.C. de; Hertefeldt, T. d'; Frouz, J. ; Hedlund, K. ; Hemerik, L. ; Hol, W.H.G. ; Hotes, S. ; Mortimer, S.R. ; Setälä, H. ; Sgardelis, S.P. ; Uteseny, K. ; Putten, W.H. van der; Wolters, V. ; Bardgett, R.D. - \ 2013
    Proceedings of the National Academy of Sciences of the United States of America 110 (2013)35. - ISSN 0027-8424 - p. 14296 - 14301.
    nitrogen mineralization - carbon sequestration - bacterial community - mycorrhizal fungi - biomass - scale - intensification - decomposition - biodiversity - agriculture
    Intensive land use reduces the diversity and abundance of many soil biota, with consequences for the processes that they govern and the ecosystem services that these processes underpin. Relationships between soil biota and ecosystem processes have mostly been found in laboratory experiments and rarely are found in the field. Here, we quantified, across four countries of contrasting climatic and soil conditions in Europe, how differences in soil food web composition resulting from land use systems (intensive wheat rotation, extensive rotation, and permanent grassland) influence the functioning of soils and the ecosystem services that they deliver. Intensive wheat rotation consistently reduced the biomass of all components of the soil food web across all countries. Soil food web properties strongly and consistently predicted processes of C and N cycling across land use systems and geographic locations, and they were a better predictor of these processes than land use. Processes of carbon loss increased with soil food web properties that correlated with soil C content, such as earthworm biomass and fungal/bacterial energy channel ratio, and were greatest in permanent grassland. In contrast, processes of N cycling were explained by soil food web properties independent of land use, such as arbuscular mycorrhizal fungi and bacterial channel biomass. Our quantification of the contribution of soil organisms to processes of C and N cycling across land use systems and geographic locations shows that soil biota need to be included in C and N cycling models and highlights the need to map and conserve soil biodiversity across the world.
    Soil and freshwater and marine sediment food webs: their structure and function
    Krumins, J.A. ; Oevelen, D. van; Bezemer, T.M. ; Deyn, G.B. de; Hol, W.H.G. ; Donk, E. van; Boer, W. de; Ruiter, P.C. de; Middelburg, J.J. ; Monroy, F. ; Soetaert, K. ; Thébault, E. ; Koppel, J. van de; Veen, J.A. van; Viketoft, M. ; Putten, W.H. van der - \ 2013
    Bioscience 63 (2013)1. - ISSN 0006-3568 - p. 35 - 42.
    global carbon-cycle - terrestrial ecosystems - real ecosystems - climate-change - biodiversity - stability - communities - limitation - patterns - sequestration
    The food webs of terrestrial soils and of freshwater and marine sediments depend on adjacent aboveground or pelagic ecosystems for organic matter input that provides nutrients and energy. There are important similarities in the flow of organic matter through these food webs and how this flow feeds back to primary production. In both soils and sediments, trophic interactions occur in a cycle in which consumers stimulate nutrient cycling such that mineralized resources are made available to the primary producers. However, aquatic sediments and terrestrial soils differ greatly in the connectivity between the production and the consumption of organic matter. Terrestrial soils and shallow aquatic sediments can receive organic matter within hours of photosynthesis when roots leak carbon, whereas deep oceanic sediments receive organic matter possibly months after carbon assimilation by phytoplankton. This comparison has implications for the capacity of soils and sediments to affect the global carbon balance.
    Testing the paradox of enrichment along a land use gradient in a multitrophic aboveground and belowground community
    Meyer, K.M. ; Vos, M. ; Hol, W.H.G. ; Mooij, W.M. ; Termorshuizen, A.J. ; Putten, W.H. van der - \ 2012
    PLoS ONE 7 (2012)11. - ISSN 1932-6203 - 9 p.
    plant-mediated interactions - inducible defenses - biological-control - shoot herbivores - insect herbivory - root - performance - biodiversity - competition - ecosystems
    In the light of ongoing land use changes, it is important to understand how multitrophic communities perform at different land use intensities. The paradox of enrichment predicts that fertilization leads to destabilization and extinction of predator-prey systems. We tested this prediction for a land use intensity gradient from natural to highly fertilized agricultural ecosystems. We included multiple aboveground and belowground trophic levels and land use-dependent searching efficiencies of insects. To overcome logistic constraints of field experiments, we used a successfully validated simulation model to investigate plant responses to removal of herbivores and their enemies. Consistent with our predictions, instability measured by herbivore-induced plant mortality increased with increasing land use intensity. Simultaneously, the balance between herbivores and natural enemies turned increasingly towards herbivore dominance and natural enemy failure. Under natural conditions, there were more frequently significant effects of belowground herbivores and their natural enemies on plant performance, whereas there were more aboveground effects in agroecosystems. This result was partly due to the “boom-bust” behavior of the shoot herbivore population. Plant responses to herbivore or natural enemy removal were much more abrupt than the imposed smooth land use intensity gradient. This may be due to the presence of multiple trophic levels aboveground and belowground. Our model suggests that destabilization and extinction are more likely to occur in agroecosystems than in natural communities, but the shape of the relationship is nonlinear under the influence of multiple trophic interactions.
    Idiosyncrasy in ecology - What's in a word?
    Hol, W.H.G. ; Meyer, K.M. ; Putten, W.H. van der - \ 2011
    Frontiers in Ecology and the Environment 9 (2011)8. - ISSN 1540-9295 - p. 431 - 433.
    Individuals in a community context: Neighboring plants structure the composition of arbuscular mycorrhizal fungi in individual ragwort plants
    Voorde, T.F.J. van de; Putten, W.H. van der; Hol, W.H.G. ; Gamper, H.A. ; Bezemer, T.M. - \ 2010
    In: The future of Biodiversity: Genes, Species, Ecosystems. - Giessen, Germany : Justus-Liebig-University - p. 241 - 241.
    Biological Invasions and Soil Biodiversity
    Putten, W.H. van der; Hol, W.H.G. - \ 2010
    In: European Atlas Of Soil Biodiversity Luxemburg : European Union - ISBN 9789279158063 - p. 58 - 59.
    Comparing arbuscular mycorrhizal communities of individual plants in a grassland biodiversity experiment
    Voorde, T.F.J. van de; Putten, W.H. van der; Gamper, H.A. ; Hol, W.H.G. ; Bezemer, T.M. - \ 2010
    New Phytologist 186 (2010)3. - ISSN 0028-646X - p. 746 - 754.
    fungal communities - senecio-jacobaea - species-diversity - ribosomal-rna - roots - colonization - productivity - variability - ecology - soil
    Plants differ greatly in the soil organisms colonizing their roots. However, how soil organism assemblages of individual plant roots can be influenced by plant community properties remains poorly understood. We determined the composition of arbuscular mycorrhizal fungi (AMF) in Jacobaea vulgaris plants, using terminal restriction fragment length polymorphism (T-RFLP). The plants were collected from an experimental field site with sown and unsown plant communities. Natural colonization was allowed for 10 yr in sown and unsown plots. Unsown plant communities were more diverse and spatially heterogeneous than sown ones. Arbuscular mycorrhizal fungi diversity did not differ between sown and unsown plant communities, but there was higher AMF assemblage dissimilarity between individual plants in the unsown plant communities. When we grew J. vulgaris in field soil that was homogenized after collection in order to rule out spatial variation, no differences in AMF dissimilarity between sown and unsown plots were found. Our study shows that experimental manipulation of plant communities in the field, and hence plant community assembly history, can influence the AMF communities of individual plants growing in those plant communities. This awareness is important when interpreting results from field surveys and experimental ecological studies in relation to plant–symbiont interactions
    Reduction of rare soil microbes modifies plant-herbivore interactions
    Hol, W.H.G. ; Boer, W. de; Termorshuizen, A.J. ; Meyer, K.M. ; Schneider, J.M.H. ; Dam, N.M. van; Veen, J.A. van; Putten, W.H. van der - \ 2010
    Ecology Letters 13 (2010). - ISSN 1461-023X - p. 292 - 301.
    ecosystem function relationship - 16s ribosomal-rna - myzus-persicae - diversity - biodiversity - communities - rhizobacteria - gradients - dynamics - biomass
    Rare species are assumed to have little impact on community interactions and ecosystem processes. However, very few studies have actually attempted to quantify the role of rare species in ecosystems. Here we compare effects of soil community assemblages on plantherbivore interactions and show that reduction of rare soil microbes increases both plant biomass and plant nutritional quality. Two crop plant species growing in soil where rare microbes were reduced, had tissues of higher nutritional quality, which theoretically makes them more susceptible to pest organisms such as shoot-feeding aphids and rootfeeding nematodes. Reduction of rare microbes increased aphid body size in the absence of nematodes; nematodes always reduced aphid body size independent of the soil microbial community. This study is the first to show that rare soil microbes are not redundant but may play a role in crop protection by enhancing aboveground and belowground plant defence. It remains to be tested whether these are direct effects of rare soil microbes on plants and herbivores, or indirect effects via shifts in the microbial soil community assemblages.
    Linking plant community heterogeneity to arbuscular mycorrhizae colonizing individual plants: A molecular field study
    Voorde, T.F.J. van de; Putten, W.H. van der; Gamper, H.A. ; Hol, W.H.G. ; Bezemer, T.M. - \ 2010
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