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P.c.e.m. De Rooij Van Der Goes - One of the best experts on this subject based on the ideXlab platform.
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Vertical migration of nematodes and soil-borne fungi to developing roots of Ammophila arenaria (L.) link after sand accretion
Applied Soil Ecology, 1998Co-Authors: P.c.e.m. De Rooij Van Der Goes, B. A. M. Peters, W.h. Van Der PuttenAbstract:Ammophila arenaria benefits from regular burial of windblown beach sand as it allows escape from soilborne pathogens (nematodes and fungi). The present study was done to obtain more insight into the timing and order of migration of the soil organisms towards the newly formed roots. Accordingly, plants were grown in non-sterilized root zone soil, buried by 20 cm of beach sand and harvested periodically during one growing season. Plants were buried in November. After 17 weeks, the internodes of the planted seedlings elongated and again 10 weeks later, in May, new roots began to develop. The majority of plant parasitic nematodes remained in the original core until root formation started in the deposited layer. Juveniles of Heterodera spp. successfully infected the roots, formed cysts and produced an offspring in October, resulting in high numbers of larvae at the end of the experiment. In February, at the first harvest of plants, fungi were isolated from soil and buried shoots in the whole deposited layer, although it was still winter. During the growing season a shift in the community of fungi in soil and buried shoots occurred in both the original core and the deposited layer. In both layers, the plant pathogenic fungi were gradually replaced by saprophytes. As all fungal and nematode species were able to colonize the deposited sand layer within one year, we conclude that both fungi and nematodes in the root zone of A. arenaria are very well adapted to sand deposition. Because of the fast migration rate of both pathogenic fungi and parasitic nematodes, the window for A. arenaria to escape in time from its soil-borne pathogens seems to be narrow. [KEYWORDS: clonal growth; colonisation; soil pathogens; interactions; Heterodera spp.; sand dunes Plant-parasitic nematodes; breviligulata poaceae; morphology; organisms; decline; growth; dunes
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Soil-borne plant pathogens of Ammophila arenaria in coastal foredunes
1996Co-Authors: P.c.e.m. De Rooij Van Der GoesAbstract:Ammophila arenaria (Marram grass) is the most dominant sand-fixing plant species in the Dutch coastal foredunes. This species has a natural ability to emerge from being buried and is therefore used to stabilize the coastal foredunes. On seaward slopes where plants are buried regularly with windblown sand, plants retain their vigour, but start to degenerate when sand accumulation diminishes. One of the factors that may cause degeneration at stabilized sites is the infection of roots by nematodes and fungi. Burial by fresh windblown sand may enable the plants to overcome these harmful soil organisms. In the present study, the nature of the soil-borne disease and its relationship with sand deposition is investigated. In a field survey, a wide range of nematodes and fungi were isolated from the root zone of A. arenaria . Subsequent inoculation-experiments showed that adding single fungal species did not reduce the growth of seedlings whereas combining all commonly found fungi together did, thus indicating synergistic effects. Adding 80 times more individuals of the semi- endoparasitic nematode Telotylenchus ventralis than present in natural soil reduced the growth of seedlings to the same extent as in natural soil. Several groups of soil organisms, especially those groups that include plant-parasitic nematodes, have shown to affect the growth of A. arenaria Burial with unsterilized root zone sand was less beneficial for plant growth than burial with sterilized or beach sand. This implies that plants are able to escape infection by soil organisms through upward growth following sand accumulation. Fungi colonized the freshly deposited layer of sand faster than plant-parasitic nematodes. Furthermore, it could be shown that in windblown soil numbers of fungal propagules and nematodes were reduced. Rejuvenation of stands along the accumulating edges of blowouts can, therefore, be explained by the reduced inoculum pressure of plant-pathogenic organisms in the deposited soil. The amount of sand and the time when sand is deposited are important components in the chances of A. arenaria to escape infection by soil organisms.
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Effects of sand deposition on the interaction between Ammophila arenaria, plant-parasitic nematodes, and pathogenic fungi
Canadian Journal of Botany, 1995Co-Authors: P.c.e.m. De Rooij Van Der Goes, W.h. Van Der Putten, B. A. M. PetersAbstract:Ammophila arenaria is a dominant sand-fixing plant species of the European coastal foredunes. It remains vigorous under regular burial conditions on seaward slopes, but starts to degenerate when sand accumulation diminishes. Several hypotheses have been put forward to explain this degeneration. In this study, we test the hypothesis that upward growth of plants following sand burial enables them to escape harmful soil organisms. Plants in a degenerating field stand of A. arenaria and potted plants grown in sterilized sand (outdoor pot experiment) were buried with sterilized or nonsterilized sand. Burial in both sterilized and nonsterilized sand resulted in stem elongation, increased numbers of living shoots, and increased shoot and root biomass. However, when plants were grown in and buried with sterilized sand, the numbers of shoots were significanlty higher than those buried with nonsterilized sand. The new root zone of buried plants was colonized by pathogenic soil organisms (nematodes and fungi) during the same growing season. It is concluded that by upward growth through pathogen-free sand, the plants benefit, at least temporarily, from escaping its pathogens and parasites. Key words: clonal growth, upward growth, migration, soil-borne disease, growth reduction.
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effects of sand deposition on the interaction between Ammophila arenaria plant parasitic nematodes and pathogenic fungi
Botany, 1995Co-Authors: P.c.e.m. De Rooij Van Der Goes, W.h. Van Der Putten, B. A. M. PetersAbstract:Ammophila arenaria is a dominant sand-fixing plant species of the European coastal foredunes. It remains vigorous under regular burial conditions on seaward slopes, but starts to degenerate when sand accumulation diminishes. Several hypotheses have been put forward to explain this degeneration. In this study, we test the hypothesis that upward growth of plants following sand burial enables them to escape harmful soil organisms. Plants in a degenerating field stand of A. arenaria and potted plants grown in sterilized sand (outdoor pot experiment) were buried with sterilized or nonsterilized sand. Burial in both sterilized and nonsterilized sand resulted in stem elongation, increased numbers of living shoots, and increased shoot and root biomass. However, when plants were grown in and buried with sterilized sand, the numbers of shoots were significantly higher than those buried with nonsterilized sand. The new root zone of buried plants was colonized by pathogenic soil organisms (nematodes and fungi) during the same growing season. It is concluded that by upward growth through pathogen-free sand, the plants benefit, at least temporarily, from escaping its pathogens and parasites. [KEYWORDS: Clonal growth; upward growth; migration; soil-borne disease; growth reduction Harmful soil organisms; hippophae-rhamnoides l; growth;breviligulata; succession; ecology]
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the role of plant parasitic nematodes and soil borne fungi in the decline of Ammophila arenaria l link
New Phytologist, 1995Co-Authors: P.c.e.m. De Rooij Van Der GoesAbstract:summary In coastal foredunes, Ammophila arenaria (L.) Link grows vigorously when it is buried regularly by windblown sand and degenerates at stabilized sites. Nematodes and soil-borne fungi were found to be involved in its decline. In order to establish their role in the disease complex, seedlings of A. arenaria were inoculated with several groups of potentially harmful soil organisms that were isolated from its root zone. Inoculation of single species of fungi did not reduce the growth of the seedlings, but combining all fungi that were commonly found in the Dutch coastal foredunes significantly reduced growth to about 80% of that in sterilized soil. This indicates synergistic effects between commonly found plant pathogenic fungi. The addition of large numbers of the nematode Telotylenchus ventralis, the only species that could be successfully grown on A. arenaria in the laboratory, reduced plant growth to the same level as in non-sterile soil, but numbers were 80 times greater than in the latter soil. Inoculation with relatively large numbers of T. ventralis in combination with the commonly occurring fungi reduced plant growth in sterilized soil to a level similar to that in non-sterile soil. The involvement of other species of nematodes, such as Heterodera spp. or Meloidogyne maritima, in the decline of A. arenaria in non-sterile soil could not be proven in inoculation experiments with sterile soil, but it is likely that these species may also be involved. It is concluded, therefore, that several different combinations of soil organisms can be harmful to A. arenaria, so that natural decline is not caused by one simple well defined pathosystem.
Wim H. Van Der Putten - One of the best experts on this subject based on the ideXlab platform.
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Responses of root-feeding nematodes (Helicotylenchus spp.) to local and non-local populations of the host plant Ammophila arenaria
Applied Soil Ecology, 2008Co-Authors: Catarina Schreck Reis, Helena Freitas, Wim H. Van Der PuttenAbstract:The root-feeding nematode community of wild plants may vary throughout their natural range. Little is known about how the variation of wild plants along their range affects their relationship with root-feeding nematodes. In the present study, we examined local and non-local combinations of host plants and root-feeding nematodes to test the hypothesis that nematode reproduction is favoured by local hosts. In two indoor experiments, we exposed populations of the wild dune grass Ammophila arenaria from northern and southern European coastal sand dunes to plant parasitic nematode species (Helicotylenchus spp.) from those same geographical origins. First, we used the southern nematode species to determine whether the effect of a local versus a non-local host may depend on nematode density. Then, in a cross-inoculation experiment we investigated how both nematode species performed with their local, as compared to the non-local hosts. In both experiments, plant biomass and ontogenetic characteristics were not significantly different between the northern and southern populations. The applied nematode densities did not have a negative impact on plant performance. This allowed us to consider the response of the two different nematode species and their host plants without co-varying differences in plant responses. Reproduction of the nematode species differed according to host origin, but contrary to what we expected, nematode species did not perform better on their local hosts. Helicotylenchus n. sp., the southern species originating from Portugal, performed better on the non-local than on the local host. Male to female ratios were significantly different between the two nematode populations and were lowest in Helicotylenchus pseudorobustus from The Netherlands. Female and juveniles percentages were also quite distinct, with more females in the nematode species from The Netherlands and more juveniles in the nematode species from Portugal. We concluded that ectoparasitic root-feeding nematodes Helicotylenchus spp. do not necessarily perform best on their local host population of the foredune grass A. arenaria. Our results imply that the natural distribution of Helicotylenchus spp. along the European coast is determined by other factors than host populations. These other factors that could be abiotic, e.g. water availability, or biotic, e.g. local natural enemies adapted to Helicotylenchus spp. Introducing plant genotypes from other parts of the natural range will, therefore, not necessarily lead to reduced abundance of semi-endo or ectoparasitic root-feeding nematodes.
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Mechanism of control of root-feeding nematodes by mycorrhizal fungi in the dune grass Ammophila arenaria.
The New phytologist, 2006Co-Authors: Eduardo De La Peña, Helena Freitas, Susana Rodríguez Echeverría, Wim H. Van Der Putten, Maurice MoensAbstract:Root-feeding herbivores can affect plant performance and the composition of natural plant communities, but there is little information about the mechanisms that control root herbivores in natural systems. This study explores the interactions between the pioneer dune grass Ammophila arenaria, arbuscular mycorrhizal fungi (AMF) and the root-feeding nematode Pratylenchus penetrans. Our objectives were to determine whether AMF can suppress nematode infection and reproduction and to explore the mechanisms of nematode control by AMF. A sequential inoculation experiment and a split-root experiment were designed to analyse the importance of plant tolerance and resistance and of direct competition between AMF and P. penetrans for the root herbivore and the plant. Root infection and multiplication of P. penetrans were significantly reduced by the native inoculum of AMF. Plant preinoculation with AMF further decreased nematode colonization and reproduction. Nematode suppression by AMF did not occur through a systemic plant response but through local mechanisms. Our results suggest that AMF are crucial for the control of root-feeding nematodes in natural systems and illustrate that locally operating mechanisms are involved in this process. [KEYWORDS: bottom-up control ; coastal dunes ; multitrophic interactions ; nematode control ; plant ; mutualists ; Pratylenchus sp. ; root-feeding nematodes]
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Soil feedback effects to the foredune grass Ammophila arenaria by endoparasitic root-feeding nematodes and whole soil communities
Soil Biology and Biochemistry, 2005Co-Authors: E. Pernilla Brinkman, Sep R. Troelstra, Wim H. Van Der PuttenAbstract: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.
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Release from native root herbivores and biotic resistance by soil pathogens in a new habitat both affect the alien Ammophila arenaria in South Africa.
Oecologia, 2004Co-Authors: Irma C. Knevel, Ursula M. Hertling, Thomas Lans, Frank B. J. Menting, Wim H. Van Der PuttenAbstract:Many native communities contain exotic plants that pose a major threat to indigenous vegetation and ecosystem functioning. Therefore the enemy release hypothesis (ERH) and biotic resistance hypothesis (BRH) were examined in relation to the invasiveness of the introduced dune grass Ammophila arenaria in South Africa. To compare plant-soil feedback from the native habitat in Europe and the new habitat in South Africa, plants were grown in their own soil from both Europe and South Africa, as well as in sterilised and non-sterilised soils from a number of indigenous South African foredune plant species. While the soil feedback of most plant species supports the ERH, the feedback from Sporobolus virginicus soil demonstrates that this plant species may contribute to biotic resistance against the introduced A. arenaria, through negative feedback from the soil community. Not only the local plant species diversity, but also the type of plant species present seemed to be important in determining the potential for biotic resistance. As a result, biotic resistance against invasive plant species may depend not only on plant competition, but also on the presence of plant species that are hosts of potential soil pathogens that may negatively affect the invaders. In conclusion, exotic plant species such as A. arenaria in South Africa that do not become highly invasive, may experience the ERH and BRH simultaneously, with the balance between enemy escape versus biotic resistance determining the invasiveness of a species in a new habitat.
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Endoparasitic nematodes reduce multiplication of ectoparasitic nematodes, but do not prevent growth reduction of Ammophila arenaria (L.) Link (marram grass)
Applied Soil Ecology, 2004Co-Authors: E. Pernilla Brinkman, Johannes A. Van Veen, Wim H. Van Der PuttenAbstract: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.
R.a. Lubke - One of the best experts on this subject based on the ideXlab platform.
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indigenous and Ammophila arenaria dominated dune vegetation on the south african cape coast
Applied Vegetation Science, 1999Co-Authors: Ursula M. Hertling, R.a. LubkeAbstract:. Communities formed by the potentially invasive European Ammophila arenaria (marram grass) are compared with those dominated by indigenous dune plant species in coastal dune systems. Sampling of communities was carried out along the Cape coast for species richness, species diversity, importance values and species associations. The influence of soil and other environmental factors on vegetation were also compared. While species richness values in A. arenaria communities appear similar to those of indigenous dune plant communities, diversity indices are significantly lower. However, on the basis of importance values of individual species, A. arenaria does not show extreme dominance to the exclusion of other species, as it does on the North American Pacific coast, where it has also been introduced. Because of its growth in dense tufts, A. arenaria is accompanied mostly by small chamaephytes and therophytes, while indigenous stands support more phanerophytes. Moreover, A. arenaria forms weaker species associations than dominant indigenous dune plant species. The alien status of A. arenaria in South Africa is confirmed by applying classification and ordination analyses which failed to differentiate A. arenaria communities according to their geographical origin as achieved with indigenous communities. This may be attributed to the lack of vigorous indigenous plants in A. arenaria communities, which accounts for the low variety in species composition of A. arenaria communities along the coastline. With regard to environmental factors, A. arenaria communities were observed to be less sensitive to extrinsic factors, such as climate, than indigenous dune plant communities. Results confirm that A. arenaria is an alien plant species in South Africa, but do not imply its invasiveness in the present or near future.
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Indigenous and Ammophila arenaria‐dominated dune vegetation on the South African Cape coast
Applied Vegetation Science, 1999Co-Authors: Ursula M. Hertling, R.a. LubkeAbstract:. Communities formed by the potentially invasive European Ammophila arenaria (marram grass) are compared with those dominated by indigenous dune plant species in coastal dune systems. Sampling of communities was carried out along the Cape coast for species richness, species diversity, importance values and species associations. The influence of soil and other environmental factors on vegetation were also compared. While species richness values in A. arenaria communities appear similar to those of indigenous dune plant communities, diversity indices are significantly lower. However, on the basis of importance values of individual species, A. arenaria does not show extreme dominance to the exclusion of other species, as it does on the North American Pacific coast, where it has also been introduced. Because of its growth in dense tufts, A. arenaria is accompanied mostly by small chamaephytes and therophytes, while indigenous stands support more phanerophytes. Moreover, A. arenaria forms weaker species associations than dominant indigenous dune plant species. The alien status of A. arenaria in South Africa is confirmed by applying classification and ordination analyses which failed to differentiate A. arenaria communities according to their geographical origin as achieved with indigenous communities. This may be attributed to the lack of vigorous indigenous plants in A. arenaria communities, which accounts for the low variety in species composition of A. arenaria communities along the coastline. With regard to environmental factors, A. arenaria communities were observed to be less sensitive to extrinsic factors, such as climate, than indigenous dune plant communities. Results confirm that A. arenaria is an alien plant species in South Africa, but do not imply its invasiveness in the present or near future.
Ursula M. Hertling - One of the best experts on this subject based on the ideXlab platform.
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Release from native root herbivores and biotic resistance by soil pathogens in a new habitat both affect the alien Ammophila arenaria in South Africa.
Oecologia, 2004Co-Authors: Irma C. Knevel, Ursula M. Hertling, Thomas Lans, Frank B. J. Menting, Wim H. Van Der PuttenAbstract:Many native communities contain exotic plants that pose a major threat to indigenous vegetation and ecosystem functioning. Therefore the enemy release hypothesis (ERH) and biotic resistance hypothesis (BRH) were examined in relation to the invasiveness of the introduced dune grass Ammophila arenaria in South Africa. To compare plant-soil feedback from the native habitat in Europe and the new habitat in South Africa, plants were grown in their own soil from both Europe and South Africa, as well as in sterilised and non-sterilised soils from a number of indigenous South African foredune plant species. While the soil feedback of most plant species supports the ERH, the feedback from Sporobolus virginicus soil demonstrates that this plant species may contribute to biotic resistance against the introduced A. arenaria, through negative feedback from the soil community. Not only the local plant species diversity, but also the type of plant species present seemed to be important in determining the potential for biotic resistance. As a result, biotic resistance against invasive plant species may depend not only on plant competition, but also on the presence of plant species that are hosts of potential soil pathogens that may negatively affect the invaders. In conclusion, exotic plant species such as A. arenaria in South Africa that do not become highly invasive, may experience the ERH and BRH simultaneously, with the balance between enemy escape versus biotic resistance determining the invasiveness of a species in a new habitat.
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indigenous and Ammophila arenaria dominated dune vegetation on the south african cape coast
Applied Vegetation Science, 1999Co-Authors: Ursula M. Hertling, R.a. LubkeAbstract:. Communities formed by the potentially invasive European Ammophila arenaria (marram grass) are compared with those dominated by indigenous dune plant species in coastal dune systems. Sampling of communities was carried out along the Cape coast for species richness, species diversity, importance values and species associations. The influence of soil and other environmental factors on vegetation were also compared. While species richness values in A. arenaria communities appear similar to those of indigenous dune plant communities, diversity indices are significantly lower. However, on the basis of importance values of individual species, A. arenaria does not show extreme dominance to the exclusion of other species, as it does on the North American Pacific coast, where it has also been introduced. Because of its growth in dense tufts, A. arenaria is accompanied mostly by small chamaephytes and therophytes, while indigenous stands support more phanerophytes. Moreover, A. arenaria forms weaker species associations than dominant indigenous dune plant species. The alien status of A. arenaria in South Africa is confirmed by applying classification and ordination analyses which failed to differentiate A. arenaria communities according to their geographical origin as achieved with indigenous communities. This may be attributed to the lack of vigorous indigenous plants in A. arenaria communities, which accounts for the low variety in species composition of A. arenaria communities along the coastline. With regard to environmental factors, A. arenaria communities were observed to be less sensitive to extrinsic factors, such as climate, than indigenous dune plant communities. Results confirm that A. arenaria is an alien plant species in South Africa, but do not imply its invasiveness in the present or near future.
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Indigenous and Ammophila arenaria‐dominated dune vegetation on the South African Cape coast
Applied Vegetation Science, 1999Co-Authors: Ursula M. Hertling, R.a. LubkeAbstract:. Communities formed by the potentially invasive European Ammophila arenaria (marram grass) are compared with those dominated by indigenous dune plant species in coastal dune systems. Sampling of communities was carried out along the Cape coast for species richness, species diversity, importance values and species associations. The influence of soil and other environmental factors on vegetation were also compared. While species richness values in A. arenaria communities appear similar to those of indigenous dune plant communities, diversity indices are significantly lower. However, on the basis of importance values of individual species, A. arenaria does not show extreme dominance to the exclusion of other species, as it does on the North American Pacific coast, where it has also been introduced. Because of its growth in dense tufts, A. arenaria is accompanied mostly by small chamaephytes and therophytes, while indigenous stands support more phanerophytes. Moreover, A. arenaria forms weaker species associations than dominant indigenous dune plant species. The alien status of A. arenaria in South Africa is confirmed by applying classification and ordination analyses which failed to differentiate A. arenaria communities according to their geographical origin as achieved with indigenous communities. This may be attributed to the lack of vigorous indigenous plants in A. arenaria communities, which accounts for the low variety in species composition of A. arenaria communities along the coastline. With regard to environmental factors, A. arenaria communities were observed to be less sensitive to extrinsic factors, such as climate, than indigenous dune plant communities. Results confirm that A. arenaria is an alien plant species in South Africa, but do not imply its invasiveness in the present or near future.
W.h. Van Der Putten - One of the best experts on this subject based on the ideXlab platform.
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first record of helicotylenchus varicaudatus yuen 1964 nematoda hoplolaimidae parasitizing Ammophila arenaria l link in portuguese coastal sand dunes
Phytopathologia Mediterranea, 2010Co-Authors: Schreck C Reis, W.h. Van Der Putten, M Vieira Dos C Santos, M Marais, M S N De A Santos, Henk Duyts, Helena Freitas, I M O De AbrantesAbstract:Summary. A spiral nematode, Helicotylenchus varicaudatus Yuen, 1964, parasitizing Ammophila arenaria (L.) Link, the dominant grass in the Portuguese coastal sand dunes, is reported from Portugal for the first time and raises to seven the number of Helicotylenchus species detected in Portugal. A redescription of the species, with illustrations, and light and scanning electron microscope images of both female and male specimens, is presented. The rDNA containing the internal transcribed spacer regions (ITS) of H. varicaudatus was analysed with ITS-RFLP using the restriction endonuclease Hinf I. Molecular data from the ribosomal small subunit (SSU) (18S) confirmed the identification.
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Can root-feeders alter the composition of AMF communities? Experimental evidence from the dune grass Ammophila arenaria
Basic and Applied Ecology, 2009Co-Authors: Susana Rodríguez-echeverría, Maurice Moens, Helena Freitas, E. De La Peña, W.h. Van Der PuttenAbstract:Root herbivores and plant mutualists, such as arbuscular mycorrhizal fungi (AMF), have a significant effect on the structure and dynamic of plant communities. Nevertheless, the interactions between the two groups of organisms in natural ecosystems are far from understood. We carried out an inoculation experiment to examine the effect of two root herbivores, Pratylenchus penetrans and P. dunensis (Nematoda), on the composition of the AMF communities associated with two populations of the dune grass Ammophila arenaria. The outcome of the interaction in terms of plant and nematode performance was also analyzed. The total percentage of AMF colonization was not affected by the presence of root-feeders, but they did alter the composition of the AMF communities inside the roots. These changes were dependent on the root-feeder species and the original AMF community: the most severe alterations were observed in the mycorrhizal plants from Wales attacked by P. penetrans. Plant growth was impaired in plants from Wales inoculated with AMF and P. dunensis, which suggests a highly species-specific synergistic interaction with negative consequences for the plant. Root infection by the nematodes was reduced in all mycorrhizal plants when compared to non-mycorrhizal plants. However, a significant reduction of the final number of nematodes was observed only in the mycorrhizal plants from one population
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genetic diversity and differentiation of Ammophila arenaria l link as revealed by issr markers
Journal of Coastal Research, 2008Co-Authors: Susana Rodriguezecheverria, Helena Freitas, W.h. Van Der PuttenAbstract:Abstract Ammophila arenaria (L.) Link (marram grass) is the most important sand-fixing plant species along the northwestern European and Mediterranean coast, and it is also planted worldwide for sand dune stabilization. In spite of the intense use of this species in foredune restoration and stabilization programs, little is known about the genetic diversity within and between populations. We analyzed the genetic diversity of seven European populations of A. arenaria using inter-simple sequence repeats (ISSR) markers. The studied populations were selected in Wales, England, Belgium, the Netherlands, Portugal, and France. One half of the populations showed similar values of genetic diversity. The lowest values (Nei's index =0.17) were found in the population from the Netherlands, which had been established after a foredune reinforcement project, and in a declining population in the south of Portugal. Statistical and phylo-genetic analyses revealed genetic differences between populations, and northern and so...
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PLANT-PARASITIC NEMATODES ASSOCIATED WITH Ammophila arenaria (L.) LINK IN PORTUGUESE COASTAL SAND DUNES
2005Co-Authors: C. Schreck Reis, Helena Freitas, W.h. Van Der PuttenAbstract:Summary. Portuguese sand dunes extend over a total length of 450 Km and include more than half of the country’s coastline. In the mobile part of the Portuguese sand dunes, Ammophila arenaria (L.) Link (Marram Grass) is the dominant and, often, the only naturally occurring plant species. The unrivalled contribution of A. arenaria to sand stabilization and dune formation is related to its extensive root and rhizome system and its vertical growth, stimulated by sand deposition. Because work on plant parasitic nematodes in dunes has mostly been done in more northerly temperate climate regions, little information on the warmer and drier climate regions is available. Therefore, in order to enhance knowledge on nematodes found in dunes in such regions, we present results of a survey of plant parasitic nematodes in the roots and rhizosphere of A. arenaria in two dune systems along the Portuguese coast. In the most northern population, the number and diversity of nematodes was higher than in the south of the country, and A. arenaria plants were more vigorous. Only two of the three endoparasitic nematode genera known to parasitize A. arenaria in north-western Europe were present in the Portuguese dunes.
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Competition between endoparasitic nematodes and effect on biomass of Ammophila arenaria (marram grass) as affected by timing of inoculation and plant age
Nematology, 2005Co-Authors: E.p. Brinkman, Henk Duyts, W.h. Van Der PuttenAbstract:AbstractWe 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.
