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Henk Schat - One of the best experts on this subject based on the ideXlab platform.

  • A comparison of antimony accumulation and tolerance among Achillea wilhelmsii, Silene vulgaris and Thlaspi arvense
    Plant and Soil, 2016
    Co-Authors: Naser Jamali Hajiani, Seyed Majid Ghaderian, Naser Karimi, Henk Schat
    Abstract:

    Aims The uptake and tolerance of antimonite [Sb(III)] and antimonate [Sb(V)] were investigated in two populations of Achillea wilhelmsii, one from strongly Sb-enriched mine soil, the other from uncontaminated soil, in comparison with non-metallicolous Silene vulgaris and Thlaspi arvense.

  • a comparison of lead accumulation and tolerance among heavy metal hyperaccumulating and non hyperaccumulating metallophytes
    Plant and Soil, 2012
    Co-Authors: Ahmad Mohtadi, Seyed Majid Ghaderian, Henk Schat
    Abstract:

    The aim of the present study was to compare lead accumulation and tolerance among heavy metal hyperaccumulating and non-hyperaccumulating metallophytes. To this purpose, we compared Pb tolerance and accumulation in hydroponics among calamine and non-calamine populations of Silene vulgaris, Noccaea caerulescens, and Matthiola flavida. We established the effects of Ca on Pb tolerance and accumulation in M. flavida, and measured exchangeable soil Pb and Ca at two calamine sites. Results revealed that calamine populations of S. vulgaris and N. caerulescens were Pb hypertolerant, but the calamine M. flavida population was not. Pb hyperaccumulation capacity was exclusively found in one of the calamine N. caerulescens populations. 1) Pb hypertolerance is sometimes lacking in metallophyte populations from strongly Pb-enriched soil, probably due to a relatively high level of exchangeable soil Ca, 2) Ca effectively counteracts Pb uptake and Pb toxicity, 3) The tendency to hyperaccumulate Pb is a population-specific phenomenon in N. caerulescens, 4) Pb hypertolerance in N. caerulescens is not necessarily associated with a tendency to hyperaccumulate Pb, 5) apparent natural Pb hyperaccumulation in M. flavida is not reproducible in hydroponics, probably due to the absence of air-born contamination in laboratory experiments.

  • the role of phytochelatins in constitutive and adaptive heavy metal tolerances in hyperaccumulator and non hyperaccumulator metallophytes
    Journal of Experimental Botany, 2002
    Co-Authors: Henk Schat, Riet Vooijs, Merce Llugany, Jeanette Hartleywhitaker, Petra M Bleeker
    Abstract:

    Using the g-glutamylcysteine synthetase inhibitor, L-buthionine-[S,R]-sulphoximine (BSO), the role for phytochelatins (PCs) was evaluated in Cu, Cd, Zn, As, Ni, and Co tolerance in non-metallicolous and metallicolous, hypertolerant populations of Silene vulgaris (Moench) Garcke, Thlaspi caerulescens J.&C. Presl., Holcus lanatus L., and Agrostis castellana Boiss. et Reuter. Based on plant-internal PCthiol to metal molar ratios, the metals’ tendency to induce PC accumulation decreased in the order As/Cd/Cu > Zn > Ni/Co, and was consistently higher in non-metallicolous plants than in hypertolerant ones, except for the case of As. The sensitivities to Cu, Zn, Ni, and Co were consistently unaffected by BSO treatment, both in non-metallicolous and hypertolerant plants, suggesting that PC-based sequestration is not essential for constitutive tolerance or hypertolerance to these metals. Cd sensitivity was considerably increased by BSO, though exclusively in plants lacking Cd hypertolerance, suggesting that adaptive cadmium hypertolerance is not dependent on PC-mediated sequestration. BSO dramatically increased As sensitivity, both in non-adapted and As-hypertolerant plants, showing that PC-based sequestration is essential for both normal constitutive tolerance and adaptive hypertolerance to this metalloid. The primary function of PC synthase in plants and algae remains elusive.

  • enhanced copper tolerance in Silene vulgaris moench garcke populations from copper mines is associated with increased transcript levels of a 2b type metallothionein gene
    Plant Physiology, 2001
    Co-Authors: Nathalie A L M Van Hoof, Henk Schat, Jos A C Verkleij, Wilfried H O Ernst, Henk W J Hakvoort, Viivi H Hassinen, Koos F Ballintijn, Sirpa Karenlampi, Arja Tervahauta
    Abstract:

    Silene vulgaris (Moench) Garcke has evolved populations with extremely high levels of copper tolerance. To evaluate the role of metallothioneins (MTs) in copper tolerance in S. vulgaris, we screened a cDNA library derived from a highly copper-tolerant population using Arabidopsis-based MT probes and identified an MT2b-like gene. When expressed in yeast, this gene, SvMT2b , restored cadmium and copper tolerance in different hypersensitive strains. Northern-blot analysis and quantitative reverse transcriptase-PCR showed that plants from the copper-tolerant S. vulgaris populations had significantly higher transcript levels of SvMT2b than plants from the copper-sensitive populations, both in roots and shoots and with and without copper exposure. Southern-blot analysis suggested that the higher expression of the latter allele was caused by gene amplification. Segregating families of crosses between copper-sensitive and copper-tolerant plants exhibited a 1 to 3 segregation for SvMT2b expression. Allele-specific PCR showed that low-expression F 3 plants were homozygous for the allele inherited from the copper-sensitive parent, whereas high-expression plants possessed at least one allele from the tolerant parent. SvMT2b expression did not cosegregate with copper tolerance in crosses between sensitive and tolerant plants. However, a significant cosegregation with copper tolerance did occur in families derived from crosses between moderately tolerant F 3 plants with different SvMT2b genotypes. Thus, overexpression of SvMT2b conferred copper tolerance although only within the genetic background of a copper tolerant plant.

  • toxicity of arsenate in Silene vulgaris accumulation and degradation of arsenate induced phytochelatins
    New Phytologist, 1999
    Co-Authors: F E C Sneller, Henk Schat, W M Ten Bookum, Paul L M Koevoets, L M Van Heerwaarden, F J L Kraaijeveldsmit, Jos A C Verkleij
    Abstract:

    The results presented in this paper describe the short- and long-term toxicity of arsenate in Silene vulgaris. Short-term toxicity, measured as inhibition of root elongation, depended on phosphate nutrition, arsenate being much less toxic at high phosphate supply. At low phosphate levels more arsenic was taken up by the plants. Under chronic exposure, toxicity (measured as inhibition of biomass production) did not increase with time. In addition, the accumulation of phytochelatins (PCs) as a function of toxicity and duration of exposure was studied. Short-term PC accumulation (over a 3 d period) was positively correlated with exposure. Isolation of peptide complexes from prolongedly exposed plants showed that PC

Riet Vooijs - One of the best experts on this subject based on the ideXlab platform.

  • the role of phytochelatins in constitutive and adaptive heavy metal tolerances in hyperaccumulator and non hyperaccumulator metallophytes
    Journal of Experimental Botany, 2002
    Co-Authors: Henk Schat, Riet Vooijs, Merce Llugany, Jeanette Hartleywhitaker, Petra M Bleeker
    Abstract:

    Using the g-glutamylcysteine synthetase inhibitor, L-buthionine-[S,R]-sulphoximine (BSO), the role for phytochelatins (PCs) was evaluated in Cu, Cd, Zn, As, Ni, and Co tolerance in non-metallicolous and metallicolous, hypertolerant populations of Silene vulgaris (Moench) Garcke, Thlaspi caerulescens J.&C. Presl., Holcus lanatus L., and Agrostis castellana Boiss. et Reuter. Based on plant-internal PCthiol to metal molar ratios, the metals’ tendency to induce PC accumulation decreased in the order As/Cd/Cu > Zn > Ni/Co, and was consistently higher in non-metallicolous plants than in hypertolerant ones, except for the case of As. The sensitivities to Cu, Zn, Ni, and Co were consistently unaffected by BSO treatment, both in non-metallicolous and hypertolerant plants, suggesting that PC-based sequestration is not essential for constitutive tolerance or hypertolerance to these metals. Cd sensitivity was considerably increased by BSO, though exclusively in plants lacking Cd hypertolerance, suggesting that adaptive cadmium hypertolerance is not dependent on PC-mediated sequestration. BSO dramatically increased As sensitivity, both in non-adapted and As-hypertolerant plants, showing that PC-based sequestration is essential for both normal constitutive tolerance and adaptive hypertolerance to this metalloid. The primary function of PC synthase in plants and algae remains elusive.

  • heavy metal induced accumulation of free proline in a metal tolerant and a nontolerant ecotype of Silene vulgaris
    Physiologia Plantarum, 1997
    Co-Authors: Henk Schat, Shanti S Sharma, Riet Vooijs
    Abstract:

    Accumulation of free proline in response to Cu, Cd and Zn was studied in nontolerant and metal-tolerant Silene vulgaris (Moench) Garcke. In the nontolerant ecotype these metals induced a massive accumulation of proline, especially in the leaves. When compared at equimolar concentrations in the nutrient solution, Cu was the most effective inducer, followed by Cd and Zn, respectively. However, when compared at equal toxic strength, as estimated from the degree of root growth inhibition, proline accumulation decreased in the order Cd > Zn > Cu. The threshold exposure levels for proline accumulation coincided with the highest no-effect-concentrations for root growth. In the metal-tolerant ecotype the constitutive proline concentration in the leaves was 5 to 6 times higher than in the nontolerant ecotype. Exposure to Cu and Zn, however, was without any effect on the leaf proline concentration, even at exposure levels that caused a 50% root growth inhibition. Only Cd, when present at concentrations above the highest no-effect-concentration for root growth, induced a further increase of the leaf proline content. Reducing transpiration by placing the plants under a transparent polyethylene cover almost completely inhibited proline accumulation, even at metal accumulation rates in the leaves that caused a 10-fold increase of the proline level in leaves of uncovered plants. The results demonstrate that metal-induced proline accumulation depends on the development of a metal-induced water deficit in the leaves. Differential metal-induced proline accumulation in distinctly metal-tolerant ecotypes is a consequence, rather than a cause of differential metal tolerance.

  • multiple tolerance and co tolerance to heavy metals in Silene vulgaris a co segregation analysis
    New Phytologist, 1997
    Co-Authors: Henk Schat, Riet Vooijs
    Abstract:

    summary Plants from metalliferous soils often exhibit combined tolerance to different heavy metals. Such tolerance could rely either on the possession of a combination of different metal-specific tolerance mechanisms (‘multiple tolerance’), or on less specific mechanisms that pleiotropically confer tolerance to different metals (‘co-tolerance’). In this study, we examined the co-segregation of tolerances to Cu, Zn, Ni, Co and Cd in crosses between distinctly tolerant ecotypes of Silene vulgaris (Moench) Garcke. The results demonstrate non-pleiotropic genetic control of tolerance to Cu, Zn and Cd. Tolerance to Ni and Co, on the other hand, seems to represent the pleiotropic byproduct of the tolerance allele of one particular locus for zinc tolerance.

  • identical major gene loci for heavy metal tolerances that have independently evolved in different local populations and subspecies of Silene vulgaris
    Evolution, 1996
    Co-Authors: Henk Schat, Riet Vooijs, Eric Kuiper
    Abstract:

    Heavy metal tolerant Silene vulgaris plants, originating from different metalliferous sites in Germany and one in Ireland, were crossed to each other and to nontolerant plants from a nonmetalliferous site in The Netherlands. Analysis of the crosses suggested that there were two distinct major gene loci for zinc tolerance among a total of five tolerant populations. The tolerance loci for zinc, copper, and cadmium in the Irish plants were shown to be identical with those in the German populations. It is argued that the occurrence of common major genes for tolerance among different geographically isolated populations must have resulted from independent parallel evolution in local nontolerant ancestral populations. Each of the tolerances studied seems to be controlled by only a few specific major genes.

F Menichini - One of the best experts on this subject based on the ideXlab platform.

  • wild mediterranean dietary plants as inhibitors of pancreatic lipase
    Phytotherapy Research, 2012
    Co-Authors: Filomena Conforti, Valentina Perri, F Menichini, Mariangela Marrelli, Dimitar Uzunov, Giancarlo Statti
    Abstract:

    Lipids are essential compounds for all living organisms. Agents that inhibit fat digestion are of theoretical benefit in the treatment of obesity. A total of 18 species (21 hydroalcoholic extracts) of edible plants from Calabria region (Italy) were evaluated for their in vitro pancreatic lipase inhibitory activity. Lipase activity was measured by monitoring the hydrolysis of p-NPC, which releases the yellow chromogen, p-nitrophenol. The aqueous ethanol extracts of Portulaca oleracea (leaves) and Silene vulgaris (leaves) exhibited the strongest inhibitory effect on lipase. The amounts of total phenolics, measured by Folin-Ciocalteu method, varied widely in the different analysed extracts and ranged from 29 to 482 mg/g of extract. In this study, the findings do not show any relationship between lipase inhibitory activity and total phenolic content.

  • wild mediterranean dietary plants as inhibitors of pancreatic lipase
    Phytotherapy Research, 2012
    Co-Authors: Filomena Conforti, Valentina Perri, F Menichini, Mariangela Marrelli, Dimitar Uzunov, Giancarlo Statti
    Abstract:

    Lipids are essential compounds for all living organisms. Agents that inhibit fat digestion are of theoretical benefit in the treatment of obesity. A total of 18 species (21 hydroalcoholic extracts) of edible plants from Calabria region (Italy) were evaluated for their in vitro pancreatic lipase inhibitory activity. Lipase activity was measured by monitoring the hydrolysis of p-NPC, which releases the yellow chromogen, p-nitrophenol. The aqueous ethanol extracts of Portulaca oleracea (leaves) and Silene vulgaris (leaves) exhibited the strongest inhibitory effect on lipase. The amounts of total phenolics, measured by Folin-Ciocalteu method, varied widely in the different analysed extracts and ranged from 29 to 482 mg/g of extract. In this study, the findings do not show any relationship between lipase inhibitory activity and total phenolic content. Copyright © 2011 John Wiley & Sons, Ltd.

Wilfried H O Ernst - One of the best experts on this subject based on the ideXlab platform.

  • enhanced copper tolerance in Silene vulgaris moench garcke populations from copper mines is associated with increased transcript levels of a 2b type metallothionein gene
    Plant Physiology, 2001
    Co-Authors: Nathalie A L M Van Hoof, Henk Schat, Jos A C Verkleij, Wilfried H O Ernst, Henk W J Hakvoort, Viivi H Hassinen, Koos F Ballintijn, Sirpa Karenlampi, Arja Tervahauta
    Abstract:

    Silene vulgaris (Moench) Garcke has evolved populations with extremely high levels of copper tolerance. To evaluate the role of metallothioneins (MTs) in copper tolerance in S. vulgaris, we screened a cDNA library derived from a highly copper-tolerant population using Arabidopsis-based MT probes and identified an MT2b-like gene. When expressed in yeast, this gene, SvMT2b , restored cadmium and copper tolerance in different hypersensitive strains. Northern-blot analysis and quantitative reverse transcriptase-PCR showed that plants from the copper-tolerant S. vulgaris populations had significantly higher transcript levels of SvMT2b than plants from the copper-sensitive populations, both in roots and shoots and with and without copper exposure. Southern-blot analysis suggested that the higher expression of the latter allele was caused by gene amplification. Segregating families of crosses between copper-sensitive and copper-tolerant plants exhibited a 1 to 3 segregation for SvMT2b expression. Allele-specific PCR showed that low-expression F 3 plants were homozygous for the allele inherited from the copper-sensitive parent, whereas high-expression plants possessed at least one allele from the tolerant parent. SvMT2b expression did not cosegregate with copper tolerance in crosses between sensitive and tolerant plants. However, a significant cosegregation with copper tolerance did occur in families derived from crosses between moderately tolerant F 3 plants with different SvMT2b genotypes. Thus, overexpression of SvMT2b conferred copper tolerance although only within the genetic background of a copper tolerant plant.

  • life cycle phases of a zinc and cadmium resistant ecotype of Silene vulgaris in risk assessment of polymetallic mine soils
    Environmental Pollution, 2000
    Co-Authors: Wilfried H O Ernst, H J M Nelissen
    Abstract:

    Short-term exposure of plants to heavy metals is often used for risk assessment of metal-enriched soils (OECD guideline 208) without considering the reliability of the assessment for long-term exposure, i.e. for the completion of a plant's life-cycle. In the present study with 15 orogenic soils three phases of the life-cycle of a Zn–Cd-resistant ecotype of Silene vulgaris were studied to improve risk assessment of metal-enriched soils. The first phase, i.e. emergence of seedlings was not related to the water-soluble or total metal concentration of the soils. Seedling mortality was low as long as the water-soluble metal concentration did not surpass 0.15 μmol Zn and 0.04 μmol Cu g−1 dry soil. Curtailment of the life-cycle prior to flowering, i.e. the vegetative growth as second phase, occurred on those soils where roots and shoots were heavily enriched by Zn already in the seedling phase. In the third phase, i.e. the generative phase, time to flowering and yield differences between orogenic soils were substantial, but soil metal concentrations could not be directly related to timing of reproduction or biomass. Ranking of data showed a high inconsistency of the responses to metal exposure during the first phases of the life-cycle. It is concluded that total plant mass and seed mass are the only realistic endpoints of life-cycle bioassays in risk assessment as long as ranks are inconsistent between two successive early phases of the life-cycle.

  • combination toxicology of metal enriched soils physiological responses of a zn and cd resistant ecotype of Silene vulgaris on polymetallic soils
    Environmental and Experimental Botany, 2000
    Co-Authors: Wilfried H O Ernst, H J M Nelissen, Wilma Ten M Bookum
    Abstract:

    Plants of an ecotype of Silene vulgaris (Caryophyllaceae) originating from a Cd-Pb-Zn mine at Plombiere (Belgium) were grown on 15 polymetallic soils for a full life-cycle to investigate physiological responses which can help explain previously reported disorders in plants. The degree of regulation of the metal concentration in the young seedlings was a very reliable indicator of the subsequent plant performance. Uptake of Zn could be regulated up to 200 nmol water-soluble Zn g−1 dry soil without surpassing 7 μmol Zn g−1 dry leaf tissue supporting the hypothesis of a high regulating potential of Zn-resistant ecotypes. As soon as a certain ecotype-specific threshold was surpassed the Zn concentration in all plant tissues strongly increased. The Cu concentration in roots and shoots had no threshold and showed the tendency to increase near linearly with the external Cu soil concentration. Similar behaviours were found for Cd, Mn and Pb. The metal concentration of seeds was the lowest of all plant parts; nevertheless it increased linearly with increasing concentration of Fe and Zn in the soil. From visible symptoms the degree of chlorosis was positively related with the concentration of Zn, but not with that of Cu, and interrelated with Fe availability. High cyanidin concentrations in leaves were not indicating a surplus of heavy metals, but deficiency in phosphorus and to a lesser degree in nitrogen. Phytochelatins (PCs) were only present in measurable amounts in leaves of plants grown on soils rich in Cu; but PCs amounts in the early vegetative phase could not be related to vegetative and seed biomass at the reproductive stage. Therefore, it is concluded that PCs are a less reliable indicator of metal toxicity during a full life-cycle than the metal concentration of young seedlings.

  • the impact of elevated uv b 280 320 nm radiation levels on the reproduction biology of a highland and a lowland population of Silene vulgaris
    Plant Ecology, 1997
    Co-Authors: J W M Van De Staaij, E Bolink, J Rozema, Wilfried H O Ernst
    Abstract:

    A highland (altitude 1600 m) and a lowland (altitude –2 m) population of the perennial herb Silene vulgaris were tested on the effects of elevated levels of UV-B radiation on their reproductivity. Highland populations receive higher natural UV-B doses than lowland populations. Therefore adaptation to high UV-B levels of the highland population is to be expected. The lowland population showed a decrease in the number of seed producing flowers and the number of seeds produced per plant under elevated UV-B levels. The highland population increased the number of seeds per plant under elevated UV-B levels. In both populations individual seed mass as well as seed germination percentages were unaffected by the UV-B flux received by the parental plant. Possible effects of UV-B induced alterations in reproductivity on the geographical distribution of the different populations are discussed.

  • phytochelatins in cadmium sensitive and cadmium tolerant Silene vulgaris chain length distribution and sulfide incorporation
    Plant Physiology, 1994
    Co-Authors: J A De Knecht, Henk Schat, Jos A C Verkleij, Paul L M Koevoets, M Van Dillen, Wilfried H O Ernst
    Abstract:

    In response to a range of Cd concentrations, the root tips of Cd-tolerant plants of Silene vulgaris exhibit a lower rate of PC production accompanied by a lower rate of longer chain PC synthesis than those of Cd-sensitive plants. At the same Cd exposure level, stable PC-Cd complexes are more rapidly formed in the roots of Cd-sensitive plants than in those of tolerant plants. At an equal PC concentration in the roots, the PC composition and the amount of sulfide incorporated per unit of PC-thiol is the same in both populations. Although these compounds might play some role in mechanisms that contribute to Cd detoxification, the ability to produce these compounds in greater amounts is not, itself, the mechanism that produces increased Cd tolerance in tolerant S. vulgaris plants.

David E Mccauley - One of the best experts on this subject based on the ideXlab platform.

  • intraspecific variation in mitochondrial genome sequence structure and gene content in Silene vulgaris an angiosperm with pervasive cytoplasmic male sterility
    New Phytologist, 2012
    Co-Authors: Daniel B Sloan, Douglas R Taylor, David E Mccauley, Karel Muller, Helena Storchova
    Abstract:

    Summary In angiosperms, mitochondrial-encoded genes can cause cytoplasmic male sterility (CMS), resulting in the coexistence of female and hermaphroditic individuals (gynodioecy). We compared four complete mitochondrial genomes from the gynodioecious species Silene vulgaris and found unprecedented amounts of intraspecific diversity for plant mitochondrial DNA (mtDNA). Remarkably, only about half of overall sequence content is shared between any pair of genomes. The four mtDNAs range in size from 361 to 429 kb and differ in gene complement, with rpl5 and rps13 being intact in some genomes but absent or pseudogenized in others. The genomes exhibit essentially no conservation of synteny and are highly repetitive, with evidence of reciprocal recombination occurring even across short repeats (< 250 bp). Some mitochondrial genes exhibit atypically high degrees of nucleotide polymorphism, while others are invariant. The genomes also contain a variable number of small autonomously mapping chromosomes, which have only recently been identified in angiosperm mtDNA. Southern blot analysis of one of these chromosomes indicated a complex in vivo structure consisting of both monomeric circles and multimeric forms. We conclude that S. vulgaris harbors an unusually large degree of variation in mtDNA sequence and structure and discuss the extent to which this variation might be related to CMS.

  • mitochondrial heteroplasmy and paternal leakage in natural populations of Silene vulgaris a gynodioecious plant
    Molecular Biology and Evolution, 2009
    Co-Authors: Stephanie A Pearl, Mark E Welch, David E Mccauley
    Abstract:

    It is currently thought that most angiosperms transmit their mitochondrial genomes maternally. Maternal transmission limits opportunities for genetic heterogeneity (heteroplasmy) of the mitochondrial genome within individuals. Recent studies of the gynodioecious species Silene vulgaris and Silene acaulis, however, document both direct and indirect evidence of mitochondrial heteroplasmy, suggesting that the mitochondrial genome is at times transmitted via paternal leakage. This heteroplasmy allows the generation of multi-locus recombinants, as documented in recent studies of both species. A prior study that employed quantitative PCR (q-PCR) on a limited sample provided direct evidence of heteroplasmy in the mitochondrial gene atp1 in S. vulgaris. Here, we apply the q-PCR methods to a much larger sample and extend them to incorporate the study of an additional atp1 haplotype along with two other haplotypes of the mitochondrial gene cox1 to evaluate the origin, extent, and transmission of mitochondrial genome heteroplasmy in S. vulgaris. We first calibrate our q-PCR methods experimentally and then use them to quantify heteroplasmy in 408 S. vulgaris individuals sampled from 22 natural populations located in Virginia, New York, and Tennessee. Sixty-one individuals exhibit heteroplasmy, including five that exhibited the joint heteroplasmy at both loci that is a prerequisite for effective recombination. The heteroplasmic individuals were distributed among 18 of the populations studied, demonstrating that heteroplasmy is a widespread phenomenon in this species. Further, we compare mother and offspring from 71 families to determine the rate of heteroplasmy gained and lost via paternal leakage and vegetative sorting across generations. Of 17 sibships exhibiting cox1 heteroplasmy and 14 sibships exhibiting atp1 heteroplasmy, more than half of the observations of heteroplasmy are generated via paternal leakage at the time of fertilization, with the rest being inherited from a heteroplasmic mother. Moreover, we show that the average paternal contribution during paternal leakage is about 12%. These findings are surprising, given that the current understanding of gynodioecy assumes that mitochondrial cytoplasmic male sterility elements are strictly maternally inherited. Knowledge of the dynamics of mitochondrial populations within individuals plays an important role in understanding the evolution of gynodioecy, and we discuss our findings within this context.

  • Variable Populations Within Variable Populations: Quantifying Mitochondrial Heteroplasmy in Natural Populations of the Gynodioecious Plant Silene vulgaris
    Oxford University Press (OUP), 2006
    Co-Authors: Mark E Welch, Michael Z Darnell, David E Mccauley
    Abstract:

    Abstract Populations of mitochondria reside within individuals. Among angiosperms, these populations are rarely considered as genetically variable entities and typically are not found to be heteroplasmic in nature, leading to the widespread assumption that plant mitochondrial populations are homoplasmic. However, empirical studies of mitochondrial variation in angiosperms are relatively uncommon due to a paucity of sequence variation. Recent greenhouse studies of Silene vulgaris suggested that heteroplasmy might occur in this species at a level that it is biologically relevant. Here, we use established qualitative methods and a novel quantitative PCR method to study the intraindividual population genetics of mitochondria across two generations in natural populations of S. vulgaris. We show incidences of heteroplasmy for mitochondrial atpA and patterns of inheritance that are suggestive of more widespread heteroplasmy at both atpA and cox1. Further, our results demonstrate that quantitative levels of mitochondrial variation within individuals are high, constituting 26% of the total in one population. These findings are most consistent with a biparental model of mitochondrial inheritance. However, selection within individuals may be instrumental in the maintenance of variation because S. vulgaris is gynodioecious. Male sterility is, in part, regulated by the mitochondrial genome, and strong selection pressures appear to influence the frequency of females in these populations.

  • the effects of inbreeding outbreeding and long distance gene flow on survivorship in north american populations of Silene vulgaris
    Journal of Ecology, 2006
    Co-Authors: Maia F Bailey, David E Mccauley
    Abstract:

    Summary 1 Silene vulgaris was introduced from Europe to North America prior to 1800. We evaluated the influence of the resulting population structure on traits related to fitness in a two generation series of glasshouse crosses. Plants were either self-fertilized, outcrossed within local populations, outcrossed between local populations or outcrossed between three geographical regions separated by > 150 km. 2 Inbreeding depression following self-fertilization occurred in nearly every maternal lineage studied but its magnitude varied among geographical regions, especially when the fitness component compared was seed germination. 3 The consequences of long-distance gene flow varied among geographical regions: crosses between some pairs of regions resulted in fitter offspring than within region outcrosses (i.e. heterosis), whereas other pairs of regions showed outbreeding depression (offspring of more distant crosses were less fit). 4 Individuals derived from self-fertilization of F1 individuals were fitter if the first crosses had been made between populations or regions rather than within populations, both in terms of seed germination and seedling survivorship. The benefits of gene flow therefore persist for at least one generation beyond that created by the gene flow event. 5 The fitness of offspring of crosses between F1 individuals and their maternal population did not depend on the relatedness of the parents of the F1. Thus, there was no evidence of outbreeding depression following recombination within F1 individuals whose creation involved gene flow. 6 Our results imply that alteration of the rate of self-fertilization or the rate of gene flow between populations of S. vulgaris could affect the demographic characters that influence population establishment and persistence in this species.

  • ecological genetics of gynodioecy in Silene vulgaris relative fitness of females and hermaphrodites during the colonization process
    Evolution, 1999
    Co-Authors: Douglas R Taylor, Steven Trimble, David E Mccauley
    Abstract:

    Recent theoretical models have addressed the influence of metapopulation dynamics on the fitness of females and hermaphrodites in gynodioecious plants. In particular, selection is thought to favor hermaphrodites during pop- ulation establishment because that sex should be less prone to pollen limitation, especially if self-fertilization is possible. However, inbreeding depression could limit this advantage. In this experimental study of Silene vulgaris, a weedy gynodioecious plant, the fitness of females and hermaphrodites was estimated from seed production in both mixed-sex populations and for individuals isolated from these populations by 20, 40, 80, or 160 m. In mixed populations females display statistically significant greater per capita seed production owing to higher capsule production and higher rates of seed germination. The fitness of both sexes declines with increasing isolation, but at different rates, such that in the 160-m treatment hermaphrodites are by far the more fit sex. Allozyme studies suggest that this differential decline is because the selling rate in hermaphrodites increases as a function of isolation, at least partially compensating for a decline in the availability of outcross pollen. Overall, the negative effects of pollen limitation on females far outweighs the negative effects of inbreeding depression following selling in hermaphrodites. Thus, ex- tinction/recolonization dynamics would appear to favor hermaphrodites as long as seed dispersal events exceed some critical distance.