Curriculum Vitae
EDUCATION
- 1998-2004 PhD degree at Wageningen University
- 1991-1996 MSc degree in Plant pathology at Wageningen Agricultural University
RESEARCH EXPERIENCE
- 2008-2009 Postdoctoral researcher at NIOO with Wim van der Putten. The effect of soil biodiversity in nature restoration.
- 2005-2007 Postdoctoral researcher at NIOO with Wim van der Putten. Analysis of existing data.
- 1998-2004 PhD position at NIOO, The Netherlands with Wim van der Putten. Interacions among endoparasitic root-feeding nematodes; consequences for nematodes and host plant.
Selected Publications
Brinkman, E. P., Duyts, H., Van der Putten, W. H. 2005
Competition between endoparasitic nematodes and effect on biomass of Ammophila arenaria (marram grass) as affected by timing of inoculation and plant age
Nematology (journal) Vol. 7, p169-178
We studied the effects of intra- and interspecific competition on the abundance of endoparasitic nematodes and assessed the consequences for biomass production of the natural dune grass Ammophila arenaria. Pratylenchus penetrans was limited by intraspecific competition and it suppressed the abundance of Heterodera arenaria, whilst the interaction between H. arenaria and Meloidogyne maritima was neutral. Pratylenchus penetrans and H. arenaria reduced plant biomass, whereas M. maritima did not. Plant biomass was not differently affected by adding one or two nematode species. When added to older plants, numbers of H. arenaria and M. maritima were higher but numbers of P penetrans were lower, resulting in less reduction of plant biomass. We discuss our results on this natural system with respect to patterns of interspecific nematode competition observed in agricultural systems.
Reprint or PDF can be requested at library@nioo.knaw.nl
Brinkman, E. P., Duyts, H., Van der Putten, W. H. 2005
Consequences of variation in species diversity in a community of root-feeding herbivores for nematode dynamics and host plant biomass
Oikos (journal) Vol. 110, Issue 3, p417-427
To date, no study has explicitly addressed effects of variation in species diversity of root-feeding herbivores on host plant biomass. Root-feeding nematodes typically occur in multi-species communities. In a three-year field experiment, we investigated how variation in species diversity of root-feeding nematodes affected nematode dynamics and response of the dune grass Ammophila arenaria to root-feeder activity. This plant species needs regular burial by fresh beach sand to remain vigorous, suggesting that A. arenaria benefits from a temporary escape from root-feeding soil organisms and that root-feeders are involved in plant degeneration in stabilized dunes. We created series of ceased and continued sand burial and added the endoparasitic nematodes Meloidogyne maritima, Heterodera arenaria and Pratylenchus penetrans alone or in combination to A. arenaria. We included treatments with and without the whole soil community, measured plant biomass and quantified numbers of nematodes. Addition of H. arenaria and P. penetrans decreased numbers of M. maritima juveniles and delayed the first appearance in time of both juveniles and females, while numbers of males only decreased when plants had been buried. Burial with sand and addition of the other two endoparasites affected numbers of H. arenaria juveniles, while numbers of P. penetrans were low and not affected. Shoot biomass of A. arenaria was lower when M. maritima had been added alone than when the three species had been added together. Addition of root zone soil decreased biomass of all plant parts. Burial with sand decreased aboveground shoot biomass, whereas it increased belowground shoot and root biomass. Our results point at idiosyncratic effects of nematode diversity on A. arenaria biomass. Heterodera arenaria and P. penetrans protected their host by reducing numbers and delaying activity of M. maritima to a later stage in the growth season, when root-feeding activity was less harmful for plant biomass development.
Reprint or PDF can be requested at library@nioo.knaw.nl
Brinkman, E. P., Troelstra, S. R., Van der Putten, W. H. 2005
Soil feedback effects to the foredune grass Ammophila arenaria by endoparasitic root-feeding nematodes and whole soil communities
Soil Biol. Biochem. (journal) Vol. 37, Issue 11, p2077-2087
In coastal foredunes, the grass Ammophila arenaria develops a soil community that contributes to die-back and replacement by later successional plant species. Root-feeding nematodes and pathogenic soil microorganisms are involved in this negative feedback. Regular burial by wind-blown beach sand results in vigorous growth of A. arenaria, probably because of enabling a temporary escape from negative soil feedback. Here, we examine the role of root-feeding nematodes as compared to the whole soil community in causing negative feedback to A. arenaria. We performed a 3-year sand burial experiment in the field and every year we determined the feedback of different soil communities to plant growth in growth chamber bioassays. In the field, we established A. arenaria in tubes with beach sand, added three endoparasitic root-feeding nematode species (Meloidogyne maritima, Heterodera arenaria and Pratylenchus penetrans) or root zone soil to the plants, and created series of ceased and continued sand burial. During three subsequent years, plant biomass was measured and numbers of nematodes were counted. Every year, bioassays were performed with the field soils and biomass of seed-grown A. arenaria plants was measured to determine the strength of feedback of the established soil communities to the plant. In the field, addition of root zone soil had a negative effect on biomass of buried plants. In the bioassays, addition of root zone soil also reduced the biomass of newly planted seedlings, however, only in the case when the field plants had not been buried with beach sand. Addition of the three endoparasitic root-feeding nematodes did not influence plant biomass in the field and in the bioassays. Our results strongly suggest that the negative feedback to A. arenaria is not due to the combination of the three endoparasitic nematodes, but to other components in the soil community, or their interactions with the nematodes. (c) 2005 Elsevier Ltd. All rights reserved.
Reprint or PDF can be requested at library@nioo.knaw.nl
Brinkman, E. P., Van Veen, J. A., Van der Putten, W. H. 2004
Endoparasitic nematodes reduce multiplication of ectoparasitic nematodes, but do not prevent growth reduction of Ammophila arenaria (L.) Link (marram grass)
Appl. Soil Ecol. (journal) Vol. 27, Issue 1, p65-75
Several studies have suggested that plants are able to control the development of specialist herbivorous invertebrates, but not that of generalists. Plants are alleged to have evolved tolerance against specialists in order to suppress the development of more damaging generalists through competition. Here, we tested whether specialist plant parasitic nematodes in the root zone of the natural dune grass Ammophila arenaria are able to suppress the development of a generalist plant parasitic nematode and therewith protect the plant. We added a generalist ectoparasite (Tylenchorhynchus ventralis) and specialist endoparasites (Heterodera arenaria, Pratylenchus penetrans, Meloidogyne maritima) in different densities to A. arenaria. We also tested whether sequential inoculation of the specialists had an additional competitive effect on T ventralis. Our results show that the specialist endoparasitic nematodes indeed suppressed the development of the generalist T ventralis, but only when the specialists were added to the plant in relatively high densities that exceeded the field density of the specialist endoparasitic nematodes. Therefore, we conclude that competition by specialist nematodes is not a likely mechanism for the regulation of the generalist plant parasite T ventralis. Sequential inoculation of endoparasites did not influence the development of T. ventralis more than inoculation at the same time. Despite their inhibiting effect on the development of T ventralis, the endoparasites did not counteract the negative effect of T ventralis on plant biomass. On the contrary, they themselves had a negative effect on shoot biomass of A. arenaria, although no effect was found on root biomass. We discuss our results in relation to other mechanisms that may regulate the population density of T ventralis. (C) 2004 Elsevier B.V. All rights reserved.
Reprint or PDF can be requested at library@nioo.knaw.nl
Van der Putten, W. H., Kowalchuk, G. A., Brinkman, E. P., Doodeman, G. T. A., Van der Kaaij, R. M., Kamp, A. F. D., Menting, F. B. J., Veenendaal, E. M. 2007
Soil feedback of exotic savanna grass relates to pathogen absence and mycorrhizal selectivity
Ecology (journal), ISSN/ISBN:0012-9658 Vol. 88, Issue 4, p978-988
Enemy release of exotic plants from soil pathogens has been tested by examining plant - soil feedback effects in repetitive growth cycles. However, positive soil feedback may also be due to enhanced benefit from the local arbuscular mycorrhizal fungi (AMF). Few studies actually have tested pathogen effects, and none of them did so in arid savannas. In the Kalahari savanna in Botswana, we compared the soil feedback of the exotic grass Cenchrus biflorus with that of two dominant native grasses, Eragrostis lehmanniana and Aristida meridionalis. The exotic grass had neutral to positive soil feedback, whereas both native grasses showed neutral to negative feedback effects. Isolation and testing of root-inhabiting fungi of E. lehmanniana yielded two host-specific pathogens that did not influence the exotic C. biflorus or the other native grass, A. meridionalis. None of the grasses was affected by the fungi that were isolated from the roots of the exotic C. biflorus. We isolated and compared the AMF community of the native and exotic grasses by polymerase chain reaction-denaturing gradient gel elecrophoresis (PCR-DGGE), targeting AMF 18S rRNA. We used roots from monospecific field stands and from plants grown in pots with mixtures of soils from the monospecific field stands. Three-quarters of the root samples of the exotic grass had two nearly identical sequences, showing 99% similarity with Glomus versiforme. The two native grasses were also associated with distinct bands, but each of these bands occurred in only a fraction of the root samples. The native grasses contained a higher diversity of AMF bands than the exotic grass. Canonical correspondence analyses of the AMF band patterns revealed almost as much difference between the native and exotic grasses as between the native grasses. In conclusion, our results support the hypothesis that release from soil-borne enemies may facilitate local abundance of exotic plants, and we provide the first evidence that these processes may occur in arid savanna ecosystems. Pathogenicity tests implicated the involvement of soil pathogens in the soil feedback responses, and further studies should reveal the functional consequences of the observed high infection with a low diversity of AMF in the roots of exotic plants.
Reprint or PDF can be requested at library@nioo.knaw.nl
Brinkman, E. P., Duyts, H., van der Putten, W. H. 2008
Interactions between root-feeding nematodes depend on plant species identity
Soil Biol. Biochem. (journal), ISSN/ISBN:0038-0717 Vol. 40, Issue 9, p2186-2193
Root-feeding nematodes play an important role in structuring the composition of natural plant communities. Little is known about the role of intra- and interspecific interactions in determining the abundance of root-feeding nematodes in natural ecosystems. We examined interactions between two ectoparasitic root-feeding nematodes on two plant species: a good host plant for both nematode species and a good host for only one of the nematodes. We tested the hypothesis that root herbivore competitiveness depends on host suitability and related the experimental results to field data. In a greenhouse, we added different densities of the nematodes Tylenchorhynchus microphasmis and Tylenchorhynchus ventralis to Ammophila arenaria (the good host for both) and Carex arenaria (a good host for T microphasmis only). Addition of T ventralis did not significantly affect multiplication of T microphasmis on both plant species. In contrast, on A. arenaria, I ventralis experienced interspecific competition. However, on C arenaria, T microphasmis facilitated multiplication of T ventralis. To explain this effect, we studied systemic plant-mediated effects in a split-root experiment. Nematode addition to one root compartment did not significantly influence nematode multiplication in the other root compartment, irrespective of nematode species identity. Therefore, the observed nematode interactions were not related to induced changes in the roots. In a two-choice experiment we tested whether host suitability was related to root attractiveness. Both nematode species were attracted to seedlings of A, arenaria, but not to C arenaria. The low multiplication of T ventralis on C. arenaria could be related to poor attraction to the roots. However, the poor attraction of T microphasmis cannot be related to poor host suitability. Adding T ventralis reduced shoot biomass of A. arenaria more than T microphasmis did, whereas for C. arenaria the effect was the reverse. The interaction of the two nematodes on A. arenaria and C. arenaria shoot biomass was insignificant. However, the effect on root biomass of A. arenaria was interactive: adding T ventralis to plants with high inoculation densities of T microphasmis further decreased root biomass. Adding T microphasmis further decreased root biomass of plants inoculated with low levels of T ventralis. Depending on host plant identity, interactions between root-feeding nematodes may lead to competition or facilitation. Our results suggest that facilitation by T microphasmis contributes to persistence of T ventralis on C. arenaria. Thus, the population dynamics of root-feeding nematodes is influenced both by host plant identity and the presence of other root-feeding nematodes. (C) 2008 Elsevier Ltd. All rights reserved.
Reprint or PDF can be requested at library@nioo.knaw.nl
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