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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    Quantitative comparison between the rhizosphere effect of Arabidopsis thaliana and co-occurring plant species with a longer life history
    Schneijderberg, Martinus ; Cheng, Xu ; Franken, Carolien ; Hollander, Mattias de; Velzen, Robin van; Schmitz, Lucas ; Heinen, Robin ; Geurts, Rene ; Putten, Wim H. van der; Bezemer, Martijn T. ; Bisseling, Ton - \ 2020
    ISME Journal (2020). - ISSN 1751-7362

    As a model for genetic studies, Arabidopsis thaliana (Arabidopsis) offers great potential to unravel plant genome-related mechanisms that shape the root microbiome. However, the fugitive life history of this species might have evolved at the expense of investing in capacity to steer an extensive rhizosphere effect. To determine whether the rhizosphere effect of Arabidopsis is different from other plant species that have a less fugitive life history, we compared the root microbiome of Arabidopsis to eight other, later succession plant species from the same habitat. The study included molecular analysis of soil, rhizosphere, and endorhizosphere microbiome both from the field and from a laboratory experiment. Molecular analysis revealed that the rhizosphere effect (as quantified by the number of enriched and depleted bacterial taxa) was ~35% lower than the average of the other eight species. Nevertheless, there are numerous microbial taxa differentially abundant between soil and rhizosphere, and they represent for a large part the rhizosphere effects of the other plants. In the case of fungal taxa, the number of differentially abundant taxa in the Arabidopsis rhizosphere is 10% of the other species’ average. In the plant endorhizosphere, which is generally more selective, the rhizosphere effect of Arabidopsis is comparable to other species, both for bacterial and fungal taxa. Taken together, our data imply that the rhizosphere effect of the Arabidopsis is smaller in the rhizosphere, but equal in the endorhizosphere when compared to plant species with a less fugitive life history.

    Community-level interactions between plants and soil biota during range expansion
    Koorem, Kadri ; Snoek, Basten L. ; Bloem, Janneke ; Geisen, Stefan ; Kostenko, Olga ; Manrubia, Marta ; Ramirez, Kelly S. ; Weser, Carolin ; Wilschut, Rutger A. ; Putten, Wim H. van der - \ 2020
    Journal of Ecology (2020). - ISSN 0022-0477
    bacteria - climate change - fungi - nematodes - plant–plant interactions - plant–soil interactions

    Plant species that expand their range in response to current climate change will encounter soil communities that may hinder, allow or even facilitate plant performance. It has been shown repeatedly for plant species originating from other continents that these plants are less hampered by soil communities from the new than from the original range. However, information about the interactions between intra-continental range expanders and soil communities is sparse, especially at community level. Here we used a plant–soil feedback experiment approach to examine if the interactions between range expanders and soil communities change during range expansion. We grew communities of range-expanding and native plant species with soil communities originating from the original and new range of range expanders. In these conditioned soils, we determined the composition of fungi and bacteria by high-throughput amplicon sequencing of the ITS region and the 16S rRNA gene respectively. Nematode community composition was determined by microscopy-based morphological identification. Then we tested how these soil communities influence the growth of subsequent communities of range expanders and natives. We found that after the conditioning phase soil bacterial, fungal and nematode communities differed by origin and by conditioning plant communities. Despite differences in bacterial, fungal and nematode communities between original and new range, soil origin did not influence the biomass production of plant communities. Both native and range expanding plant communities produced most above-ground biomass in soils that were conditioned by plant communities distantly related to them. Synthesis. Communities of range-expanding plant species shape specific soil communities in both original and new range soil. Plant–soil interactions of range expanders in communities can be similar to the ones of their closely related native plant species.

    The Kok effect revisited
    Yin, Xinyou ; Niu, Yuxi ; Putten, Peter E.L. van der; Struik, Paul C. - \ 2020
    New Phytologist (2020). - ISSN 0028-646X
    day respiration - Kok method - photorespiration - photosystem II efficiency - reassimilation - Yin method

    The Kok effect refers to the abrupt decrease around the light compensation point in the slope of net photosynthetic rate vs irradiance. Arguably, this switch arises from light inhibition of respiration, allowing the Kok method to estimate day respiration (Rd). Recent analysis suggests that increasing proportions of photorespiration (quantified as Γ*/Cc, the ratio of CO2 compensation point Γ* to chloroplast CO2 concentration, Cc) with irradiance explain much of the Kok effect. Also, the Kok method has been modified to account for the decrease in PSII photochemical efficiency (Φ2) with irradiance. Using a model that illustrates how varying Rd, Γ*/Cc, Φ2 and proportions of alternative electron transport could engender the Kok effect, we quantified the contribution of these parameters to the Kok effect measured in sunflower across various O2 and CO2 concentrations and various temperatures. Overall, the decreasing Φ2 with irradiance explained c. 12%, and the varying Γ*/Cc explained c. 25%, of the Kok effect. Maximum real light inhibition of Rd was much lower than the inhibition derived from the Kok method, but still increased with photorespiration. Photorespiration had a dual contribution to the Kok effect, one via the varying Γ*/Cc and the other via its participation in light inhibition of Rd.

    Ecology Letters (Journal)
    Putten, Wim van der - \ 2020
    Ecology Letters (2020). - ISSN 1461-023X
    Science (Journal)
    Putten, Wim van der - \ 2020
    Science (2020). - ISSN 0036-8075
    The long-term restoration of ecosystem complexity
    Moreno-Mateos, David ; Alberdi, Antton ; Morriën, Elly ; Putten, Wim H. van der; Rodríguez-Uña, Asun ; Montoya, Daniel - \ 2020
    Nature Ecology & Evolution 4 (2020)5. - ISSN 2397-334X - p. 676 - 685.

    Multiple large-scale restoration strategies are emerging globally to counteract ecosystem degradation and biodiversity loss. However, restoration often remains insufficient to offset that loss. To address this challenge, we propose to focus restoration science on the long-term (centuries to millennia) re-assembly of degraded ecosystem complexity integrating interaction network and evolutionary potential approaches. This approach provides insights into eco-evolutionary feedbacks determining the structure, functioning and stability of recovering ecosystems. Eco-evolutionary feedbacks may help to understand changes in the adaptive potential after disturbance of metacommunity hub species with core structural and functional roles for their use in restoration. Those changes can be studied combining a restoration genomics approach based on whole-genome sequencing with replicated space-for-time substitutions linking changes in genetic variation to functions or traits relevant to the establishment of evolutionarily resilient communities. This approach may set the knowledge basis for future tools to accelerate the restoration of ecosystems able to adapt to ongoing global changes.

    Ongedierte
    Putten, Wim van der - \ 2020
    A global database of soil nematode abundance and functional group composition
    Hoogen, Johan van den; Geisen, Stefan ; Wall, Diana H. ; Wardle, David A. ; Traunspurger, Walter ; Goede, Ron G.M. de; Adams, Byron J. ; Ahmad, Wasim ; Ferris, Howard ; Bardgett, Richard D. ; Bonkowski, Michael ; Campos-Herrera, Raquel ; Cares, Juvenil E. ; Caruso, Tancredi ; Brito Caixeta, Larissa de; Chen, Xiaoyun ; Costa, Sofia R. ; Creamer, Rachel ; Cunha e Castro, José Mauro da; Dam, Marie ; Djigal, Djibril ; Escuer, Miguel ; Griffiths, Bryan S. ; Gutiérrez, Carmen ; Hohberg, Karin ; Kalinkina, Daria ; Kardol, Paul ; Kergunteuil, Alan ; Korthals, Gerard ; Krashevska, Valentyna ; Kudrin, Alexey A. ; Li, Qi ; Liang, Wenju ; Magilton, Matthew ; Marais, Mariette ; Martín, José Antonio Rodríguez ; Matveeva, Elizaveta ; Mayad, El Hassan ; Mzough, E. ; Mulder, Christian ; Mullin, Peter ; Neilson, Roy ; Nguyen, Duong T.A. ; Nielsen, Uffe N. ; Okada, Hiroaki ; Rius, Juan Emilio Palomares ; Pan, Kaiwen ; Peneva, Vlada ; Pellissier, Loïc ; Silva, Julio Carlos Pereira da; Pitteloud, Camille ; Powers, Thomas O. ; Powers, Kirsten ; Quist, Casper W. ; Rasmann, Sergio ; Moreno, Sara Sánchez ; Scheu, Stefan ; Setälä, Heikki ; Sushchuk, Anna ; Tiunov, Alexei V. ; Trap, Jean ; Vestergård, Mette ; Villenave, Cecile ; Waeyenberge, Lieven ; Wilschut, Rutger A. ; Wright, Daniel G. ; Keith, Aidan M. ; Yang, Jiuein ; Schmidt, Olaf ; Bouharroud, R. ; Ferji, Z. ; Putten, Wim H. van der; Routh, Devin ; Crowther, Thomas W. - \ 2020
    Scientific Data 7 (2020)1. - ISSN 2052-4463

    As the most abundant animals on earth, nematodes are a dominant component of the soil community. They play critical roles in regulating biogeochemical cycles and vegetation dynamics within and across landscapes and are an indicator of soil biological activity. Here, we present a comprehensive global dataset of soil nematode abundance and functional group composition. This dataset includes 6,825 georeferenced soil samples from all continents and biomes. For geospatial mapping purposes these samples are aggregated into 1,933 unique 1-km pixels, each of which is linked to 73 global environmental covariate data layers. Altogether, this dataset can help to gain insight into the spatial distribution patterns of soil nematode abundance and community composition, and the environmental drivers shaping these patterns.

    A data-driven methodology reveals novel myofiber clusters in older human muscles
    Raz, Yotam ; Akker, Erik B. van den; Roest, Tijmen ; Riaz, Muhammad ; Rest, Ondine van de; Suchiman, Eka D. ; Lakenberg, Nico ; Stassen, Stefanie A. ; Putten, Maaike van; Feskens, Edith J.M. ; Reinders, Marcel J.T. ; Goeman, Jelle ; Beekman, Marian ; Raz, Vered ; Slagboom, Pieternella Eline - \ 2020
    FASEB Journal 34 (2020)4. - ISSN 0892-6638 - p. 5525 - 5537.
    bioinformatics - clustering - fibertyping - human - muscle - muscle health - myofiber - myosin heavy chain - RNA-sequencing - sarcomere

    Skeletal muscles control posture, mobility and strength, and influence whole-body metabolism. Muscles are built of different types of myofibers, each having specific metabolic, molecular, and contractile properties. Fiber classification is, therefore, regarded the key for understanding muscle biology, (patho-) physiology. The expression of three myosin heavy chain (MyHC) isoforms, MyHC-1, MyHC-2A, and MyHC-2X, marks myofibers in humans. Typically, myofiber classification is performed by an eye-based histological analysis. This classical approach is insufficient to capture complex fiber classes, expressing more than one MyHC-isoform. We, therefore, developed a methodological procedure for high-throughput characterization of myofibers on the basis of multiple isoforms. The mean fluorescence intensity of the three most abundant MyHC isoforms was measured per myofiber in muscle biopsies of 56 healthy elderly adults, and myofiber classes were identified using computational biology tools. Unsupervised clustering revealed the existence of six distinct myofiber clusters. A comparison with the visual assessment of myofibers using the same images showed that some of these myofiber clusters could not be detected or were frequently misclassified. The presence of these six clusters was reinforced by RNA expressions levels of sarcomeric genes. In addition, one of the clusters, expressing all three MyHC isoforms, correlated with histological measures of muscle health. To conclude, this methodological procedure enables deep characterization of the complex muscle heterogeneity. This study opens opportunities to further investigate myofiber composition in comparative studies.

    Distinct Biogeographic Phenomena Require a Specific Terminology: A Reply to Wilson and Sagoff
    Essl, Franz ; Dullinger, Stefan ; Genovesi, Piero ; Hulme, Philip E. ; Jeschke, Jonathan M. ; Katsanevakis, Stelios ; Kühn, Ingolf ; Lenzner, Bernd ; Pauchard, Aníbal ; Pyšek, Petr ; Rabitsch, Wolfgang ; Richardson, David M. ; Seebens, Hanno ; Kleunen, Mark Van; Putten, Wim H. van der; Vilà, Montserrat ; Bacher, Sven - \ 2020
    Bioscience 70 (2020)2. - ISSN 0006-3568 - p. 111 - 114.
    Using photorespiratory oxygen response to analyse leaf mesophyll resistance
    Yin, Xinyou ; Putten, Peter E.L. van der; Belay, Daniel ; Struik, Paul C. - \ 2020
    Photosynthesis Research 144 (2020). - ISSN 0166-8595 - p. 85 - 99.
    CO compensation point - CO transfer - Internal conductance - O response - Re-assimilation - Resistance

    Classical approaches to estimate mesophyll conductance ignore differences in resistance components for CO2 from intercellular air spaces (IAS) and CO2 from photorespiration (F) and respiration (Rd). Consequently, mesophyll conductance apparently becomes sensitive to (photo)respiration relative to net photosynthesis, (F + Rd)/A. This sensitivity depends on several hard-to-measure anatomical properties of mesophyll cells. We developed a method to estimate the parameter m (0 ≤ m ≤ 1) that lumps these anatomical properties, using gas exchange and chlorophyll fluorescence measurements where (F + Rd)/A ratios vary. This method was applied to tomato and rice leaves measured at five O2 levels. The estimated m was 0.3 for tomato but 0.0 for rice, suggesting that classical approaches implying m = 0 work well for rice. The mesophyll conductance taking the m factor into account still responded to irradiance, CO2, and O2 levels, similar to response patterns of stomatal conductance to these variables. Largely due to different m values, the fraction of (photo)respired CO2 being refixed within mesophyll cells was lower in tomato than in rice. But that was compensated for by the higher fraction via IAS, making the total re-fixation similar for both species. These results, agreeing with CO2 compensation point estimates, support our method of effectively analysing mesophyll resistance.

    Towards an integrative understanding of soil biodiversity
    Thakur, Madhav P. ; Phillips, Helen R.P. ; Brose, Ulrich ; Vries, Franciska T. De; Lavelle, Patrick ; Loreau, Michel ; Mathieu, Jerome ; Mulder, Christian ; Putten, Wim H. Van der; Rillig, Matthias C. ; Wardle, David A. ; Bach, Elizabeth M. ; Bartz, Marie L.C. ; Bennett, Joanne M. ; Briones, Maria J.I. ; Brown, George ; Decaëns, Thibaud ; Eisenhauer, Nico ; Ferlian, Olga ; Guerra, Carlos António ; König-Ries, Birgitta ; Orgiazzi, Alberto ; Ramirez, Kelly S. ; Russell, David J. ; Rutgers, Michiel ; Wall, Diana H. ; Cameron, Erin K. - \ 2020
    Biological Reviews 95 (2020)2. - ISSN 1464-7931 - p. 350 - 364.
    alpha diversity - beta diversity - biodiversity theory - metacommunity theory - neutral theory - niche theory - spatial scale - species–energy relationship - theory of island biogeography

    Soil is one of the most biodiverse terrestrial habitats. Yet, we lack an integrative conceptual framework for understanding the patterns and mechanisms driving soil biodiversity. One of the underlying reasons for our poor understanding of soil biodiversity patterns relates to whether key biodiversity theories (historically developed for aboveground and aquatic organisms) are applicable to patterns of soil biodiversity. Here, we present a systematic literature review to investigate whether and how key biodiversity theories (species–energy relationship, theory of island biogeography, metacommunity theory, niche theory and neutral theory) can explain observed patterns of soil biodiversity. We then discuss two spatial compartments nested within soil at which biodiversity theories can be applied to acknowledge the scale-dependent nature of soil biodiversity.

    Soil fauna diversity increases CO2 but suppresses N2O emissions from soil
    Lubbers, Ingrid M. ; Berg, Matty P. ; Deyn, Gerlinde B. De; Putten, Wim H. van der; Groenigen, Jan Willem van - \ 2020
    Global Change Biology 26 (2020)3. - ISSN 1354-1013 - p. 1886 - 1898.
    community composition - functional dissimilarity - GHG mitigation - net diversity effect - soil-derived GHG emission - species richness

    Soil faunal activity can be a major control of greenhouse gas (GHG) emissions from soil. Effects of single faunal species, genera or families have been investigated, but it is unknown how soil fauna diversity may influence emissions of both carbon dioxide (CO2, end product of decomposition of organic matter) and nitrous oxide (N2O, an intermediate product of N transformation processes, in particular denitrification). Here, we studied how CO2 and N2O emissions are affected by species and species mixtures of up to eight species of detritivorous/fungivorous soil fauna from four different taxonomic groups (earthworms, potworms, mites, springtails) using a microcosm set-up. We found that higher species richness and increased functional dissimilarity of species mixtures led to increased faunal-induced CO2 emission (up to 10%), but decreased N2O emission (up to 62%). Large ecosystem engineers such as earthworms were key drivers of both CO2 and N2O emissions. Interestingly, increased biodiversity of other soil fauna in the presence of earthworms decreased faunal-induced N2O emission despite enhanced C cycling. We conclude that higher soil fauna functional diversity enhanced the intensity of belowground processes, leading to more complete litter decomposition and increased CO2 emission, but concurrently also resulting in more complete denitrification and reduced N2O emission. Our results suggest that increased soil fauna species diversity has the potential to mitigate emissions of N2O from soil ecosystems. Given the loss of soil biodiversity in managed soils, our findings call for adoption of management practices that enhance soil biodiversity and stimulate a functionally diverse faunal community to reduce N2O emissions from managed soils.

    Rhizosphere and litter feedbacks to range-expanding plant species and related natives
    Manrubia, Marta ; Putten, Wim H. van der; Weser, Carolin ; Veen, Ciska G.F. - \ 2020
    Journal of Ecology 108 (2020)1. - ISSN 0022-0477 - p. 353 - 365.
    litter feedback - novel communities - plant range expansion - plant–soil feedback - rhizosphere feedback

    Plant–soil feedback (PSF) results from the net legacy effect that plants leave in the composition of soil communities and abiotic soil properties. PSF is induced by the rhizosphere and by litter inputs into the soil, however, we have little understanding of their individual contributions. Here, we examine feedback effects from the rhizosphere of living plants, decomposing litter and their combination. We used four pairs of climate warming-induced range-expanding plant species and congeneric natives, and examined PSF effects on plant biomass production, as well as on decomposition in their new range. We tested the hypothesis that the plant rhizosphere provides less negative feedback to range-expanders than to the congeneric natives, and that feedback mediated by litter decomposition does not provide such a difference because decomposers might be less specialized than pathogens. To determine PSF, we used soil from the congener species within each pair as an ‘away’ soil to indicate whether range-expanders may have lost their specialized soil biota upon arrival in the novel range. Our results show that although range-expanding plant species and their congeneric natives developed neutral PSF in both rhizosphere- and litter-conditioned soils, two of the four range-expanders produced more biomass than natives in soils conditioned by litter, that is, soils with high nutrient content. Shoot litter from two out of four range-expanding species decomposed more than that of natives, but decomposition was unaffected by soil conditioning. Synthesis. We compared PSF effects of range-expanders and congeneric natives mediated via both the rhizosphere and litter using the congeneric species as a control. Under those conditions, PSF effects were neutral and not affected by plant origin. Therefore, we conclude that studies not comparing within plant genera may overestimate the impact of plant origin on PSF. Still, even under those conditions range-expanders appeared to benefit more from high soil nutrient availability than natives, thus providing a possible advantage over congeneric natives.

    Nonlinear responses of soil nematode community composition to increasing aridity
    Xiong, Dan ; Wei, Cun Zheng ; Wubs, Jasper E.R. ; Veen, G.J. ; Liang, Wenju ; Wang, Xiaobo ; Li, Qi ; Putten, Wim H. Van der; Han, Xingguo - \ 2020
    Global Ecology and Biogeography 29 (2020)1. - ISSN 1466-822X - p. 117 - 126.
    aridity - biodiversity - global climate change - grassland transect - nonlinear response - soil nematode community

    Aim: Increasing aridity under global change is predicted to have a profound impact on the structure and functioning of terrestrial ecosystems, yet we have a poor understanding of how belowground communities respond. In order to understand the longer term responses of different trophic levels in the soil food web to increasing aridity, we investigated the abundance, richness and community similarity of the soil nematode community along a 3,200 km aridity gradient. Location: A transect across semi-arid and arid grasslands in Northern China, where the aridity ranges from.43 to.97. Time period: July and August 2012. Major taxa studied: Soil-borne Nematoda. Methods: We used generalized additive (mixed) models to analyse the abundance, richness and community similarity patterns of soil nematodes. We used structural equation modelling (SEM) to disentangle the direct and indirect environmental drivers (aridity, soil and plant variables) of the nematode community. Results: The abundance, richness and similarity of nematode communities declined nonlinearly with increasing aridity. The most pronounced decline in nematode richness and community similarity occurred in arid conditions (aridity >.80). However, the shape of the response to aridity differed among nematode feeding groups. In arid conditions, the abundance and richness of bacterial feeders were less sensitive to changes in aridity than for fungal feeders. The SEM analysis revealed that nematode community responses to aridity were not mediated via changes in plant and soil variables, but instead were affected directly by aridity. Main conclusions: Our results showed that in mesic grasslands, increasing aridity primarily caused a decline in nematode abundance, whereas increasing aridity in xeric grasslands led to a loss of nematode diversity. The nonlinear responses of nematodes to aridity could also result in nonlinear shifts in ecosystem functioning, because soil nematodes operate at various trophic levels in the soil food web, thereby influencing the performance of plants, soil biodiversity and biogeochemical cycling.

    Rhizosphere and litter feedbacks to range-expanding plant species and related natives
    Manrubia, M. ; Putten, Wim van der; Weser, Carolin ; Veen, Ciska G.F. - \ 2019
    Dryad
    litter feedback - novel communities - plant range expansion - plant-soil feedback - rhizosphere feedback
    1. Plant-soil feedback (PSF) results from the net legacy effect that plants leave in the composition of soil communities and abiotic soil properties. PSF is induced by the rhizosphere and by litter inputs into the soil, however, we have little understanding of their individual contributions. Here, we examine feedback effects from the rhizosphere of living plants, decomposing litter, and their combination. 2. We used four pairs of climate warming-induced range-expanding plant species and congeneric natives, and examined PSF effects on plant biomass production, as well as on decomposition in their new range. 3. We tested the hypothesis that the plant rhizosphere provides less negative feedback to range-expanders than to the congeneric natives, and that feedback mediated by litter decomposition does not provide such a difference because decomposers might be less specialized than pathogens. To determine PSF, we used soil from the congener species within each pair as an “away” soil to indicate whether range-expanders may have lost their specialized soil biota upon arrival in the novel range. 4. Our results show that although range-expanding plant species and their congeneric natives developed neutral PSF in both rhizosphere- and litter-conditioned soils, two of the four range-expanders produced more biomass than natives in soils conditioned by litter, i.e. soils with high nutrient content. Shoot litter from two out of four range-expanding species decomposed more than that of natives, but decomposition was unaffected by soil conditioning. 5. Synthesis. We compared PSF effects of range expanders and congeneric natives mediated via both the rhizosphere and litter using the congeneric species as a control. Under those conditions, PSF effects were neutral and not affected by plant origin. Therefore, we conclude that studies not comparing within plant genera may overestimate the impact of plant origin on PSF. Still, even under those conditions range-expanders appeared to benefit more from high soil nutrient availability than natives, thus providing a possible advantage over congeneric natives.
    Data from: Nonlinear responses of soil nematode community composition to increasing aridity
    Xiong, Dan ; Wei, Cun Zheng ; Wubs, E.R.J. ; Veen, G.J. ; Liang, Wenju ; Wang, Xiaobo ; Li, Qi ; Putten, Wim van der; Han, Xingguo - \ 2019
    Dryad
    biodiversity - aridity - soil nematode community - non-linear response - global climate change - grassland transect
    Aim: Increasing aridity under global change is predicted to have a profound impact on the structure and functioning of terrestrial ecosystems, yet we have poor understanding of how belowground communities respond. In order to understand the longer-term responses of different trophic levels in the soil food web to increasing aridity, we investigated the abundance, richness and community similarity of the soil nematode community along a 3200-km aridity gradient. Location: A transect across semi-arid and arid grasslands in Northern China, where the aridity ranges from 0.43 to 0.97. Time period: July and August 2012. Major taxa studied: Soil-borne Nematoda. Methods: We used Generalized Additive (Mixed) Models to analyze the abundance, richness and community similarity patterns of soil nematodes. We used Structural Equation Modelling (SEM) to disentangle the direct and indirect environmental drivers (aridity, soil and plant variables) of the nematode community. Results: The abundance, richness and similarity of nematode communities declined non-linearly with increasing aridity. The most pronounced decline in nematode richness and community similarity occurred under arid conditions (aridity > 0.80). However, the shape of response to aridity differed among nematode feeding groups. Under arid conditions, the abundance and richness of bacterial feeders were less sensitive to changes in aridity than fungal feeders. The SEM analysis revealed that nematode community responses to aridity were not mediated via changes in plant and soil variables, but rather were directly affected by aridity. Main conclusions: Our results show that in mesic grasslands increasing aridity primarily caused decline in nematode abundance, whereas increasing aridity in xeric grasslands led to loss of nematode diversity. The non-linear responses of nematodes to aridity could result in non-linear shifts in ecosystem functioning as well, because soil nematodes operate at various trophic levels in the soil food web, thereby influencing the performance of plants, soil biodiversity and biogeochemical cycling.
    Science (Journal)
    Putten, Wim van der - \ 2019
    Science (2019). - ISSN 0036-8075
    Inteeltbeheersing bij rashonden: de stabij
    Windig, Jack - \ 2019
    Structural Motifs of Wheat Straw Lignin Differ in Susceptibility to Degradation by the White-Rot Fungus Ceriporiopsis subvermispora
    Erven, Gijs Van; Wang, Jianli ; Sun, Peicheng ; Waard, Pieter De; Putten, Jacinta Van Der; Frissen, Guus E. ; Gosselink, Richard J.A. ; Zinovyev, Grigory ; Potthast, Antje ; Berkel, Willem J.H. Van; Kabel, Mirjam A. - \ 2019
    ACS sustainable chemistry & engineering 7 (2019)24. - ISSN 2168-0485 - p. 20032 - 20042.
    biological pretreatment - lignin quantification - ligninolysis - NMR spectroscopy - oxidation - selective delignification - single-electron transfer - stereoselectivity

    The white-rot fungus Ceriporiopsis subvermispora delignifies plant biomass extensively and selectively and, therefore, has great biotechnological potential. We previously demonstrated that after 7 weeks of fungal growth on wheat straw 70% w/w of lignin was removed and established the underlying degradation mechanisms via selectively extracted diagnostic substructures. In this work, we fractionated the residual (more intact) lignin and comprehensively characterized the obtained isolates to determine the susceptibility of wheat straw lignin's structural motifs to fungal degradation. Using 13C IS pyrolysis gas chromatography-mass spectrometry (py-GC-MS), heteronuclear single quantum coherence (HSQC) and 31P NMR spectroscopy, and size-exclusion chromatography (SEC) analyses, it was shown that β-O-4′ ethers and the more condensed phenylcoumarans and resinols were equally susceptible to fungal breakdown. Interestingly, for β-O-4′ ether substructures, marked cleavage preferences could be observed: β-O-4′-syringyl substructures were degraded more frequently than their β-O-4′-guaiacyl and β-O-4′-tricin analogues. Furthermore, diastereochemistry (threo > erythro) and γ-acylation (γ-OH > γ-acyl) influenced cleavage susceptibility. These results indicate that electron density of the 4′-O-coupled ring and local steric hindrance are important determinants of oxidative β-O-4′ ether degradation. Our findings provide novel insight into the delignification mechanisms of C. subvermispora and contribute to improving the valorization of lignocellulosic biomass.

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