The Experts below are selected from a list of 258 Experts worldwide ranked by ideXlab platform
Karin I Kohl - One of the best experts on this subject based on the ideXlab platform.
-
do Armeria maritima mill willd ecotypes from metalliferous soils and non metalliferous soils differ in growth response under zn stress a comparison by a new artificial soil method
Journal of Experimental Botany, 1997Co-Authors: Karin I KohlAbstract:Morphological and biogeographical evidence suggests that the heavy-metal ecotype of Armeria maritima (Mill.) Willd. has evolved from a hybrid group between the subspecies maritima from salt marshes and the subspecies elongata from sandy soils. As part of a study on the ecotypic differentiation in A. maritima, Zn resistance was compared in populations from these three ecotypes. To study the long-term growth response to elevated Zn concentrations, an artificial soil was made from ion-exchange resin embedded in an inert sand matrix, in which metal ions were buffered by an ion-exchange system as in natural soils. In contrast to hydroponics, this artificial soil systems is suitable for long-term cultivation and it provides more reproducible growth conditions than a soil system. The long-term growth response in the artificial soil system was compared to the growth response to elevated Zn concentrations in a sand nutrient-solution system. In short-term tests, populations from non-metalliferous soils were more sensitive to Zn concentrations of 1.0 mmol I -1 than the heavy-metal populations. However, in long-term tests, the growth of adult plants from all populations was not inhibited by Zn concentrations up to 2.8 mmol kg -1 dry soil (equivalent 26% of cation-exchange capacity). The Zn resistance of all populations could therefore be sufficient for their survival on Zn mine soils. The discrepancy between long-term tests and short-term tests is discussed with respect to the hypothesis that 'sensitive' populations may differ from 'resistant' populations in the expression of Zn-resistance mechanisms.
-
the effect of nacl on growth dry matter allocation and ion uptake in salt marsh and inland populations of Armeria maritima
New Phytologist, 1997Co-Authors: Karin I KohlAbstract:SUMMARY Salt resistance was compared in populations of Armeria maritima (Mill.) Willd. from salt marshes and from inland sites to investigate which salt-resistance-related traits are present in all populations and which are derived traits of the salt-marsh ecotype. Plants were raised from seeds from six different populations and grown on a mixture of sand and ion-exchange resin at different salinity levels. Inland populations grew better at 40 mM NaCl than with salt-free treatment and survived several months at 200 mM NaCl, and were thus as salt-resistant as many species from brackish habitats. Salt-marsh populations were as salt-resistant as euhalophytes. Growth enhancement by NaCl was related to an increase in shoot:root d. wt ratio, which was shown not to be the result of damage to the roots. Carbon allocation to roots seemed to be reduced as a consequence of a better nutrient supply at elevated NaCl concentrations. In plants from all populations, tissue tolerance of sodium and chloride (500–1000 mmol kg−1 d. wt) was higher than that in glycophytes. Na substituted for K and to some extent Ca and Mg without growth reduction. Betaines were accumulated as cytoplasmic compatible solutes by all populations, whereas proline accumulation was not involved in adjustment to long-term salt stress. The halophytic capacity to load the xylem with Na was found in all populations of A. maritima. However, the allocation of Na to the shoot started at higher salinities in inland populations than in salt-marsh populations. This was presumably due to the Na storage capacity of roots of inland populations being higher than that of coastal populations. Nevertheless, the inland populations of A. maritima were significantly salt-tolerant as a consequence of their capacity to accumulate betaines and allocate Na to the shoot; this might have facilitated the colonization of salt marshes by the species.
-
population specific traits and their implication for the evolution of a drought adapted ecotype in Armeria maritima
Plant Biology, 1996Co-Authors: Karin I KohlAbstract:: Traits contributing to drought resistance of Armeria maritima were investigated by comparing six populations of this species from sandy grasslands, heavy metal mines and salt marsh sites. The sandy soil ecotype that is influenced by periodic drought was found to allocate constitutively a higher proportion of biomass to the root system, especially to the fine roots, than the other two ecotypes. The selective advantage of this lower shoot-root ratio is presumably the delayed onset of the critical water saturation deficit because of the ability to take up additional water from deeper soil layers. Under water stress, all populations of A. maritima showed a decrease in the shoot-root ratio. Additionally, under moderate long-term water stress a decrease in (= more negative) osmotic potential was found in leaves of plants from all populations. Lowest osmotic potentials were shown by the salt marsh ecotype and the highest by one of the heavy metal populations. Osmotic adjustment was achieved passively by a reduction in osmotic volume. Accumulation of osmotically active compounds was seen only under severe water stress, when the considerable betaine contents found in all populations of A. maritima even under control conditions were further increased by severe drought. The evolution of traits related to drought adaptation in the sandy soil ecotype of A. maritima is discussed.
-
Population‐specific Traits and their Implication for the Evolution of a Drought‐adapted Ecotype in Armeria maritima
Plant Biology, 1996Co-Authors: Karin I KohlAbstract:: Traits contributing to drought resistance of Armeria maritima were investigated by comparing six populations of this species from sandy grasslands, heavy metal mines and salt marsh sites. The sandy soil ecotype that is influenced by periodic drought was found to allocate constitutively a higher proportion of biomass to the root system, especially to the fine roots, than the other two ecotypes. The selective advantage of this lower shoot-root ratio is presumably the delayed onset of the critical water saturation deficit because of the ability to take up additional water from deeper soil layers. Under water stress, all populations of A. maritima showed a decrease in the shoot-root ratio. Additionally, under moderate long-term water stress a decrease in (= more negative) osmotic potential was found in leaves of plants from all populations. Lowest osmotic potentials were shown by the salt marsh ecotype and the highest by one of the heavy metal populations. Osmotic adjustment was achieved passively by a reduction in osmotic volume. Accumulation of osmotically active compounds was seen only under severe water stress, when the considerable betaine contents found in all populations of A. maritima even under control conditions were further increased by severe drought. The evolution of traits related to drought adaptation in the sandy soil ecotype of A. maritima is discussed.
Claude Lefebvre - One of the best experts on this subject based on the ideXlab platform.
-
the zn biogeochemistry of Armeria maritima mill willd within and between population studies
Belgian Journal of Botany, 2001Co-Authors: Catherine Bernard, Claude LefebvreAbstract:A wide range of variation of Zn concentrations in leaves occurs between individuals within an Armeria maritima population growing on Zn-rich spoil heaps from an old Zn-Pb mine. Experiments on controlled soil conditions with a metallicolous A. maritima population show that there is a family (genotypical) component for Zn leaf concentrations. Specific Plumbaginaceae-excreting glands regulate to some extent the Zn concentrations in capitulum stalks and probably leaves. Under greenhouse culture conditions, a non-tolerant coastal population can grow reasonably well for several months on an highly toxic soil, accumulating two to four times more Zn in leaves and performing better in Zn accumulation per individual than mine populations. Additional examples from populations of Thlaspi caerulescens suggest the general assumption that search for genotypes efficient for phytoremediations must not be restricted to metallophyte populations.
-
cytogenetic variation in populations of Armeria maritima mill willd in relation to geographical distribution and soil stress tolerances
Botany, 1999Co-Authors: J Coulaud, Claude Lefebvre, Nasrine Barghi, Sonja SiljakyakovlevAbstract:Ten Armeria maritima (Mill.) Willd. populations (2n = 18) from contrasting ecogeographic situations were compared using 30 morphometric characters of karyotype and frequencies of abnormal metaphase and interphase cells in root-tip meristems. Despite the general symmetry and similarities, karyotypes of populations can be distinguished using a set of precise karyotypic features. Variations within populations mainly concerned the occurrence of satellites and weakly condensed areas of chromosomes. Total chromosome length measurements were congruent with flow cytometry estimates of DNA amounts. The geographical differentiation of European population karyotypes is in accordance with previously defined biochemical clustering. One population from Germany (ssp. bottendorfensis) is more similar to the American population (ssp. californica) than to the other European populations. Proposed trends of karyotype evolution are discussed in comparison with previous results on other character sets and taxonomic treatments....
-
on the evolution of heavy metal tolerant populations in Armeria maritima evidence from allozyme variation and reproductive barriers
Journal of Evolutionary Biology, 1997Co-Authors: Xavier Vekemans, Claude LefebvreAbstract:The process of ecological differentiation leading to the evolution of heavy-metal tolerant populations in Armeria maritima was studied by comparing population genetic structure and pattern of gene flow between populations growing on heavy-metal contaminated against non-contaminated sites using allozyme markers. In addition the evolution of reproductive isolation among populations was studied by measuring pollen fertility in interpopulational hybrids. The allozyme data suggested that in A. maritima multiple independent evolutionary origins of heavy-metal tolerant populations have occurred in the absence of strong genetic bottlenecks. The pattern of gene flow among populations was consistent with the model of isolation by distance with considerable gene flow between neighbor populations, and no reduction of gene flow between tolerant and non-tolerant populations. Hence it appears that substantial gene flow has not hampered genetic differentiation, probably because of the high selection pressure for heavy-metal tolerance. The pattern of reproductive isolation among populations suggests that evolution of heavy-metal tolerant populations has not triggered the development of reproductive barriers against non-tolerant populations. However, partial reproductive isolation has occurred under geographic separation.
-
On the evolution of heavy‐metal tolerant populations in Armeria maritima: evidence from allozyme variation and reproductive barriers
Journal of Evolutionary Biology, 1997Co-Authors: Xavier Vekemans, Claude LefebvreAbstract:The process of ecological differentiation leading to the evolution of heavy-metal tolerant populations in Armeria maritima was studied by comparing population genetic structure and pattern of gene flow between populations growing on heavy-metal contaminated against non-contaminated sites using allozyme markers. In addition the evolution of reproductive isolation among populations was studied by measuring pollen fertility in interpopulational hybrids. The allozyme data suggested that in A. maritima multiple independent evolutionary origins of heavy-metal tolerant populations have occurred in the absence of strong genetic bottlenecks. The pattern of gene flow among populations was consistent with the model of isolation by distance with considerable gene flow between neighbor populations, and no reduction of gene flow between tolerant and non-tolerant populations. Hence it appears that substantial gene flow has not hampered genetic differentiation, probably because of the high selection pressure for heavy-metal tolerance. The pattern of reproductive isolation among populations suggests that evolution of heavy-metal tolerant populations has not triggered the development of reproductive barriers against non-tolerant populations. However, partial reproductive isolation has occurred under geographic separation.
-
a numerical taxonomic study of Armeria maritima plumbaginaceae in north america and greenland
Botany, 1995Co-Authors: Claude Lefebvre, Xavier VekemansAbstract:Principal components analysis, discriminant analysis, cluster analysis and two level nested analysis of variance were performed on 961 herbarium specimens of Armeria maritima covering the complete geographic range of the species in North America and Greenland. Among the monomorphic, self-compatible specimens combining coarsely reticulate pollen and papillous stigma, we recognized three subspecies. Along the Pacific coast from California to Vancouver Island, the single taxon ssp. californica is proposed, which includes the formerly described var. purpurea. In arctic and subarctic regions, ssp. sibirica, which includes var. labradorica, and ssp. interior are recognized as distinct entities. The latter has a restricted distribution and can be easily distinguished morphologically owing to its glabrous calyces. The morphological variation between ssp. californica and ssp. sibirica is continuous and some overlap occurs. The best diagnostic characters are two ratios: sheath length to flower head width and outer ...
Xavier Vekemans - One of the best experts on this subject based on the ideXlab platform.
-
variation in nuclear dna content at the species level in Armeria maritima
Hereditas, 2004Co-Authors: Xavier Vekemans, C. Lefèbvre, J Coulaud, Solange Blaise, W Gruber, Sonja Siljakyakovlev, Spencer BrownAbstract:Intraspecific variation in nuclear DNA content in 19 populations of Armeria maritima was investigated. Significant differences in DNA amount among ecogeographic groups and among populations were observed. These differences are related to geographic origin, with Californian populations having 7 % more DNA than their European counterparts. Within Europe, the four ecogeographic groups tested are not distinct, whatever their geographic origin (maritime versus continental) and their ecological characteristics (heavy-metal polluted versus non-toxic soils). However, significant differences in DNA amount appeared among population clusters identified from biochemical classification of European populations based on flavonoid compounds and isozyme markers. Variation in genome size among populations was found to be significantly correlated to variation in pollen size. Weak interpopulational variation has been detected for the nucleotidic base ratio, but was not correlated to variation in DNA amount.
-
on the evolution of heavy metal tolerant populations in Armeria maritima evidence from allozyme variation and reproductive barriers
Journal of Evolutionary Biology, 1997Co-Authors: Xavier Vekemans, Claude LefebvreAbstract:The process of ecological differentiation leading to the evolution of heavy-metal tolerant populations in Armeria maritima was studied by comparing population genetic structure and pattern of gene flow between populations growing on heavy-metal contaminated against non-contaminated sites using allozyme markers. In addition the evolution of reproductive isolation among populations was studied by measuring pollen fertility in interpopulational hybrids. The allozyme data suggested that in A. maritima multiple independent evolutionary origins of heavy-metal tolerant populations have occurred in the absence of strong genetic bottlenecks. The pattern of gene flow among populations was consistent with the model of isolation by distance with considerable gene flow between neighbor populations, and no reduction of gene flow between tolerant and non-tolerant populations. Hence it appears that substantial gene flow has not hampered genetic differentiation, probably because of the high selection pressure for heavy-metal tolerance. The pattern of reproductive isolation among populations suggests that evolution of heavy-metal tolerant populations has not triggered the development of reproductive barriers against non-tolerant populations. However, partial reproductive isolation has occurred under geographic separation.
-
On the evolution of heavy‐metal tolerant populations in Armeria maritima: evidence from allozyme variation and reproductive barriers
Journal of Evolutionary Biology, 1997Co-Authors: Xavier Vekemans, Claude LefebvreAbstract:The process of ecological differentiation leading to the evolution of heavy-metal tolerant populations in Armeria maritima was studied by comparing population genetic structure and pattern of gene flow between populations growing on heavy-metal contaminated against non-contaminated sites using allozyme markers. In addition the evolution of reproductive isolation among populations was studied by measuring pollen fertility in interpopulational hybrids. The allozyme data suggested that in A. maritima multiple independent evolutionary origins of heavy-metal tolerant populations have occurred in the absence of strong genetic bottlenecks. The pattern of gene flow among populations was consistent with the model of isolation by distance with considerable gene flow between neighbor populations, and no reduction of gene flow between tolerant and non-tolerant populations. Hence it appears that substantial gene flow has not hampered genetic differentiation, probably because of the high selection pressure for heavy-metal tolerance. The pattern of reproductive isolation among populations suggests that evolution of heavy-metal tolerant populations has not triggered the development of reproductive barriers against non-tolerant populations. However, partial reproductive isolation has occurred under geographic separation.
-
a numerical taxonomic study of Armeria maritima plumbaginaceae in north america and greenland
Botany, 1995Co-Authors: Claude Lefebvre, Xavier VekemansAbstract:Principal components analysis, discriminant analysis, cluster analysis and two level nested analysis of variance were performed on 961 herbarium specimens of Armeria maritima covering the complete geographic range of the species in North America and Greenland. Among the monomorphic, self-compatible specimens combining coarsely reticulate pollen and papillous stigma, we recognized three subspecies. Along the Pacific coast from California to Vancouver Island, the single taxon ssp. californica is proposed, which includes the formerly described var. purpurea. In arctic and subarctic regions, ssp. sibirica, which includes var. labradorica, and ssp. interior are recognized as distinct entities. The latter has a restricted distribution and can be easily distinguished morphologically owing to its glabrous calyces. The morphological variation between ssp. californica and ssp. sibirica is continuous and some overlap occurs. The best diagnostic characters are two ratios: sheath length to flower head width and outer ...
-
flavonoid profiles variation in Armeria maritima mill willd
Biochemical Systematics and Ecology, 1995Co-Authors: Josiane Lauranson, Xavier Vekemans, Claude LefebvreAbstract:Abstract The leaf flavonoid content in individuals of Armeria maritima originating from populations with contrasted ecogeographical situations and belonging to seven distinct intraspecific taxa, is highly variable both quantitatively and qualitatively. Principal component analysis and comparison of frequency of individual flavonoid profiles show that congruence between classical taxonomic units and flavonoid pattern of variation is only circumstantial. The level of variability in flavonoids for ecogeographical groups of populations decrease in relation to change in breeding system from xenogamy to autogamy and to strong selection pressures (heavy metal toxicity). Populations within ecogeographical groups are significantly distinct for their level of variability.
George A F Hendry - One of the best experts on this subject based on the ideXlab platform.
-
the role of ascorbate in drought treated cochlearia atlantica pobed and Armeria maritima mill willd
New Phytologist, 1991Co-Authors: Sarah M Buckland, Adam H Price, George A F HendryAbstract:summary Cochlearia atlantica is a species rich in ascorbic acid. After 4 days of intermittent drought treatment, there was a large decrease in the concentration of ascorbate and glutathione, functioning probably as radical scavengers (anti-oxidants). Although there was no increase in lipid peroxidation (a marker of oxygen radical damage), drought treatment did result in the destruction of chlorophyll and a decrease in protein. This species showed little or no change in the activities of five enzymes usually associated with the processing of, and protection from, activated forms of oxygen. Armeria maritima showed similar decreases in relative water content and dry weight after droughting, but a quantitatively smaller decrease in ascorbate with no loss of glutathione. Instead a major response to drought, in this species, was the marked increases in the activities of superoxide dismutasc and peroxidase. Despite these increases in enzymic defences against oxygen radicals, drought treatment resulted in increased lipid peroxidation. in A. maritima. It is concluded that ascorbic acid and glutathione may play a significant role in the response to drought in C. atlantica but protection in A. maritima is largely through enzymic processing of activated farms of oxygen.
-
The role of ascorbate in drought‐treated Cochlearia atlantica Pobed. and Armeria maritima (Mill.) Willd.
New Phytologist, 1991Co-Authors: Sarah M Buckland, Adam H Price, George A F HendryAbstract:summary Cochlearia atlantica is a species rich in ascorbic acid. After 4 days of intermittent drought treatment, there was a large decrease in the concentration of ascorbate and glutathione, functioning probably as radical scavengers (anti-oxidants). Although there was no increase in lipid peroxidation (a marker of oxygen radical damage), drought treatment did result in the destruction of chlorophyll and a decrease in protein. This species showed little or no change in the activities of five enzymes usually associated with the processing of, and protection from, activated forms of oxygen. Armeria maritima showed similar decreases in relative water content and dry weight after droughting, but a quantitatively smaller decrease in ascorbate with no loss of glutathione. Instead a major response to drought, in this species, was the marked increases in the activities of superoxide dismutasc and peroxidase. Despite these increases in enzymic defences against oxygen radicals, drought treatment resulted in increased lipid peroxidation. in A. maritima. It is concluded that ascorbic acid and glutathione may play a significant role in the response to drought in C. atlantica but protection in A. maritima is largely through enzymic processing of activated farms of oxygen.
Philippe Sonnet - One of the best experts on this subject based on the ideXlab platform.
-
Leachability of cadmium, lead, and zinc in a long-term spontaneously revegetated slag heap: implications for phytostabilization
Journal of Soils and Sediments, 2013Co-Authors: David Houben, Eléonore Couder, Philippe SonnetAbstract:PurposeFor abandoned slag heaps, the spontaneous establishment of a vegetation cover is usually considered beneficial as it represents a means of phytostabilization. However, for slag containing heavy metals, such a vegetation cover has a potential long-term effect on the fate of the metals. The objective of this study was to investigate how the long-term spontaneous revegetation of a slag heap can affect the fractionation and the leachability of Cd, Zn, and Pb.Materials and methodsSoils from two plots covered by either Armeria maritima or Agrostis tenuis and a bare plot soil were sampled from a slag heap from a zinc smelting plant and characterized. The Community Bureau of Reference (BCR) sequential extraction scheme was adopted to determine the metal pools. The leachability of Cd, Pb, and Zn was assessed by means of a leaching column experiment.Results and discussionLong-term presence of a plant cover increased the proportion of Zn in the most mobile fraction and Pb in the fraction bound to organic matter. Cd distribution was relatively unaffected. Overall, the metal leachability was enhanced in the revegetated soils, notably due to higher organic anion release. However, responses of metal behavior to revegetation depended on the established plant species. The highest leachability of Cd was found in the soil covered by Agrostis tenuis , while the highest leachability of both Zn and Pb was observed in the soil below Armeria maritima .ConclusionsAny remediation strategy for metal-rich waste dumps by phytostabilization should take into careful consideration the potential long-term mobilization effect of plant establishment on heavy metals. We conclude that, when using pioneer plants for phytostabilization purposes, preference should be given to pseudo-metallophyte over hyperaccumulator species.
