Sorrel Research Articles

Links between pseudometallophytes and rhizosphere microbial communities in a metalliferous soil

Abstract Short-term improvements in soil health derived from pseudometallophytes growth and metal phytoremediation were quantified based upon specific microbial properties of potential value as bioindicators of soil functioning. To this aim, plant consortia, consisting of 1–3 pseudometallophytes with different metal-tolerance strategies (hyperaccumulator: Noccaea caerulescens ; accumulator: Rumex acetosa ; excluder: Festuca rubra ), were grown in a mine soil. At the end of the experiment, soil microbial biomass, activity, structural and functional community profiling, and stability were determined. Growing together with N. caerulescens stimulated the growth of the other two pseudometallophytes. The combination of R. acetosa and N. caerulescens extracted the highest amounts of Zn. Except for β-glucosidase, a negative correlation was found between enzyme activities and number of pseudometallophytes present in the study pots. Microbial biomass C was highest in the presence of all three pseudometallophytes. The combination of different pseudometallophyte species, which may allow for a greater exploitation of potential niche space, appears promising for phytoremediation. When quantifying soil health, the importance of measuring various types of soil microbial properties has been highlighted, as the response observed was different in each of them.

Phytohabitans flavus sp. nov., Phytohabitans rumicis sp. nov. and Phytohabitans houttuyneae sp. nov., isolated from plant roots, and emended description of the genus Phytohabitans

An actinomycete strain, designated K09-0627(T), was isolated from the roots of an orchid collected in Okinawa Prefecture, Japan. Two actinomycete strains K11-0047(T) and K11-0057(T) were isolated from the roots of Rumex acetosa and Houttuynia cordata collected in Kanagawa Prefecture, Japan. 16S rRNA gene sequence analyses indicated that the isolates belonged to the genus Phytohabitans, and that they were closely related to each other and to Phytohabitans suffuscus K07-0523(T). The DNA-DNA relatedness values between the three isolates and Phytohabitans suffuscus were below 70%. On the basis of phylogenetic analysis, DNA-DNA relatedness values and phenotypic characteristics, the strains should be classified as novel species in the genus Phytohabitans, for which the names Phytohabitans flavus sp. nov. (type strain, K09-0627(T)=JCM 17387(T)=NBRC 107702(T)=DSM 45551(T)), Phytohabitans rumicis sp. nov. (type strain, K11-0047(T)=JCM 17829(T)=NBRC 108638(T)=BCC 48146(T)) and Phytohabitans houttuyneae sp. nov. (type strain, K11-0057(T)=JCM 17830(T)=NBRC 108639(T)=BCC 48147(T)) are proposed.

Seedling growth, leaf water status and signature of stable carbon isotopes in C3 perennials exposed to natural phytochemicals

In the present study, we evaluated the seedling growth, water status and signature of stable carbon isotopes in C3 perennial species exposed to natural phytochemicals. Three perennial species, cocksfoot (Dactylis glomerata), perennial ryegrass (Lolium perenne) and common sorrel (Rumex acetosa), were grown for 30 days in perlite, watered with Hoagland solution and exposed to the phytochemicals benzoxazolin-2(3H)-one (BOA) and cinnamic acid (CA) at 0, 0.1, 0.5, 1.0 and 1.5 mM concentrations. BOA markedly decreased the leaf and root fresh weights of D. glomerata and L. perenne in a concentration-dependent manner. The leaf fresh weight (LFW) of plants treated with CA (1.5 mM) was similarly affected by showing a decrease of LFW, being the lowest in L. perenne (56%) followed by D. glomerata (46%). The relative water contents of L. perenne, D. glomerata and R. acetosa were decreased while maximum RWC reduction was observed in L. perenne. Carbon isotope discrimination in L. perenne, D. glomerata and R. acetosa were reduced following treatment with BOA and CA at 1.5 mM. BOA at 1.5 mM decreased the ratio of intercellular to ambient CO2 concentration relative to control in L. perenne, D. glomerata and R. acetosa. There was an increase in water-use efficiency in L. perenne, D. glomerata and R. acetosa after treatment with BOA and CA. The dry weight of plants treated with CA (1.5 mM) showed different patterns of variation, being lowest in L. perenne (33%) followed by D. glomerata (3%) and R. acetosa (2%). Phytotoxicity was higher for the perennial grass than for the perennial broadleaf. These results clearly demonstrate a widespread occurrence of phytotoxicity among the three species, their tolerance and relationship between carbon isotope discrimination and intrinsic water-use efficiency.

Ethnobotanical review of wild edible plants of Slovakia

This paper is an ethnobotanical review of wild edible plants gathered for consumption from the 19th century to the present day, within the present borders of Slovakia. Twenty-four sources (mainly ethnographic) documenting the culinary use of wild plants were analysed. The use of 106 species (over 3% of the Slovak flora) has been recorded. Nowadays most of them are no longer used, or used rarely, apart from a few species of wild fruits. The most frequently used plants include the fruits of <em>Rubus idaeus</em>, <em>Fragaria </em>spp., <em>Rubus </em>subgenus <em>Rubus</em>, <em>Vaccinium myrtillus</em>, <em>V. vitis-idaea</em>, <em>Fagus sylvatica</em>, <em>Corylus avellana</em>, <em>Prunus spinosa</em>, <em>Pyrus </em>spp., <em>Malus </em>spp., <em>Crataegus </em>spp. and the leaves of <em>Urtica dioica</em>, <em>Rumex acetosa</em>, Chenopodiaceae species, <em>Cardamine amara</em>, <em>Glechoma </em>spp., <em>Taraxacum </em>spp. and <em>Oxalis acetosella</em>. The most commonly used wild food taxa are nearly identical to those used in Poland, and the same negative association of wild vegetables with famine exists in Slovakia, resulting in their near complete disappearance from the present-day diet.

The phytocoenoses of anthropogenically transformed areas with a great importance for Apoidea

The paper indicates the phytocenoses most rich in bee taxons and occurring in habitats located along railway lines crossing Lublin Upland. To date, in the study area 124 basic phytocoenoses have been discovered, described and classifi ed into 12 different synecological groups. Among 52 phytocoenoses, the participation of bee flora was considerable. Most voluble phytocoenoses represent ruderal and segetal associations (<i>Artemisietea vulgaris</i>, <i>Stellarietea mediae</i> classes - 87 species), meadow and pasture associations (<i>Mollinio-Arrhenatheretea</i> - 56 species), psammophilous and xerothermic grasslands (<i>Festuco</i>- <i>Brometea</i>, <i>Koelerio glauce</i>-<i>Corynophoretea canescensis</i> - 38 species), thermophilous forest edge communities and thickets (<i>Trifolio</i>-<i>Geranietea</i> and <i>Rhamno</i>-<i>Prunetea</i> - 33 species). Significantly fewer melliferous and polleniferous taxons were noticed in mesophilous deciduous forests or thermophilous oak forests - 29 species. Most simple in structure and species richness are associations with <i>Rumex acetosa</i>, <i>Reseda lutea</i>, <i>Linaria vulgaris</i>, <i>Papaver rhoeas</i>, <i>Cirsium arvense</i>, <i>Oenothera biennis</i>, <i>Viola arvensis</i> and <i>Potentilletum anserine</i> or <i>Sisymbrietum altissimi</i>. The communities form patches (15-20 m<sup>2</sup>) with 80-100% cover of the diagnostic taxon and are of low or medium stability. The most persistent and floristically stable are <i>Tanaceto Artemisietum</i>, <i>Rudbeckio</i>- <i>Solidaginetum</i>, <i>Echio</i>-<i>Melilotetum</i>, <i>Sambucetum nigrae</i>, <i>Rubo fruticosi</i>-<i>Prunetum spinosae</i> and communities with <i>Rosa rugosa</i>, <i>Rubus caesius</i>, <i>Geranium robertianum</i>, <i>Pastinaca sativa</i>, <i>Trifolium medium</i> or <i>Euphorbia cyparissias</i>. The maintenance of the mosaic of phytocoenoses in anthropogenically transformed habitats, including those along railway lines, is of decisive importance for the protection of floristic diversity and adaptation processes of Apoidea.

Phenolic compounds from Allium schoenoprasum, Tragopogon pratensis and Rumex acetosa and their antiproliferative effects.

Experimental studies have shown that phenolic compounds have antiproliferative and tumour arresting effects. The aim of this original study was to investigate the content of phenolic compounds (PhC) in flowers of Allium schoenoprasum (chive), Tragopogon pratensis (meadow salsify) and Rumex acetosa (common sorrel) and their effect on proliferation of HaCaT cells. Antiproliferative effects were evaluated in vitro using the following concentrations of phenolic compounds in cultivation medium: 100, 75, 50 and 25 µg/mL. Phenolic composition was also determined by HPLC. The results indicate that even low concentrations of these flowers’ phenolic compounds inhibited cell proliferation significantly and the possible use of the studied herb’s flowers as sources of active phenolic compounds for human nutrition.

Wild edible plants traditionally gathered in Gorbeialdea (Biscay, Basque Country)

This ethnobotanical study aims to describe the domain of wild edible plants in Gorbeialdea (Biscay, Iberian Peninsula), and to assess the cultural importance of the different species and food categories. Field work was conducted between 2008 and 2010, interviewing 103 informants about the traditional use of wild plants for food. The edible use of 49 species was recorded, 45% of them gathered for their fruits. The most important species coincide with those registered in other regions in the north of the Iberian Peninsula (Prunus spinosa, Rubus ulmifolius, Castanea sativa, Fragaria vesca, Rumex acetosa, Vaccinium myrtillus and Arbutus unedo). However, the importance of some species and uses that had not been previously recorded as edible in the ethnobotanical literature of the Iberian Peninsula, highlights the singularity of the area. The consumption of the leaves of Fagus sylvatica, the seeds of Pinus radiata, and the shoots of Pteridium aquilinum are some examples of specific uses. The eating of the fruits of Quercus robur, and Q. ilex was common until some decades ago and is still remembered by the informants. However, the consumption of those fruits has now a social stigma, and as shown in this paper, it can be overlooked by a methodology only based on open interviews. The most important use-category was ‘fruits’, following the trend found in other northern regions of the Iberian and Italian Peninsulas. ‘Snack vegetables’ is also a relevant category, including 35% of the cited species, with a high diversity of chewed plants, mainly as hunger or thirst quenchers. On the contrary, there was a low valorization of condiments and elaborated vegetables.

Ecophysiological responses of three native herbs to phytotoxic potential of invasive Acacia melanoxylon R. Br.

Acacia melanoxylon R. Br. (Blackwood) is a native Australian species that has invaded woodlands and degraded natural habitats in the north western Iberian Peninsula (Galicia), Spain. Several phenolic (p-hydroxybenzoic, vanillic, p-coumaric, syringic, protocatequic, ferulic acids) and flavonoids (catechin, luteolin, rutin, apigenin, and quercetin) were identified from methanol extracts of flowers and phyllodes of A. melanoxylon by HPLC. Flowers and phyllodes of A. melanoxylon were soaked separately in the water in a ratio of 1:1 (w/v) for 24 h to prepare aqueous extracts (100, 75, 50 and 25%) and distilled water was used as control. The seeds of three native plants, cocksfoot (Dactylis glomerata), perennial ryegrass (Lolium perenne), common sorrel (Rumex acetosa) and a general test crop lettuce (Lactuca sativa) were grown in perlite culture and aqueous extracts of A. melanoxylon (flowers and phyllodes) were applied exogenously at various concentrations. A. melanoxylon flowers extract (100%) inhibited the shoot length of D. glomerata and L. perenne by 31 and 20% of the control, respectively. Leaf and root fresh weights of L. perenne, D. glomerata, and L. sativa were reduced after treatment with acacia flowers and phyllodes extract. Leaf relative water content of D. glomerata and L. perenne was reduced by acacia flowers and phyllodes extract at all concentrations. Both extracts reduced leaf osmotic potential in D. glomerata, L. perenne and L. sativa. Quantum efficiency of open PSII reaction centers (Fv/Fm) and quantum yield (ΦPSII) of photosystem II were decreased in L. perenne, D. glomerata; R. acetosa and L. sativa after treatment with acacia flowers/phyllodes extract at 100% concentration. Acacia flowers and phyllodes extract (100%) inhibited the qP level during all 6 days in D. glomerata, L. perenne, R. acetosa and L. sativa. A significant reduction in NPQ was observed during different days in all four plant species due to Acacia flowers and phyllodes extract (100%). The δ13C ratios were less negative in L. perenne, D. glomerata and L. sativa as compared to the control. A. melanoxylon flowers and phyllodes extract (100%) significantly reduced leaf protein contents in D. glomerata, L. perenne and in L. sativa.

Rumex acetosa Y chromosomes: constitutive or facultative heterochromatin?

Condensed Y chromosomes in Rumex acetosa L. root-tip nuclei were studied using 5-azaC treatment and immunohistochemical detection of methylated histones. Although Y chromosomes were decondensed within root meristem in vivo, they became condensed and heteropycnotic in roots cultured in vitro. 5-azacytidine (5-azaC) treatment of cultured roots caused transitional dispersion of their Y chromosome bodies, but 7 days after removal of the drug from the culture medium, Y heterochromatin recondensed and again became visible. The response of Rumex sex chromatin to 5-azaC was compared with that of condensed segments of pericentromeric heterochromatin in Rhoeo spathacea (Sw.) Steam roots. It was shown that Rhoeo chromocentres, composed of AT-rich constitutive heterochromatin, did not undergo decondensation after 5-azaC treatment. The Y-bodies observed within male nuclei of R. acetosa were globally enriched with H3 histone, demethylated at lysine 4 and methylated at lysine 9. This is the first report of histone tail-modification in condensed sex chromatin in plants. Our results suggest that the interphase condensation of Y chromosomes in Rumex is facultative rather than constitutive. Furthermore, the observed response of Y-bodies to 5-azaC may result indirectly from demethylation and the subsequent altered expression of unknown genes controlling tissue-specific Y-inactivation as opposed to the global demethylation of Y-chromosome DNA.

Allelochemical stress inhibits growth, leaf water relations, PSII photochemistry, non-photochemical fluorescence quenching, and heat energy dissipation in three C3 perennial species.

In this study, the effect of two allelochemicals, benzoxazolin-2(3H)-one (BOA) and cinnamic acid (CA), on different physiological and morphological characteristics of 1-month-old C3 plant species (Dactylis glomerata, Lolium perenne, and Rumex acetosa) was analysed. BOA inhibited the shoot length of D. glomerata, L. perenne, and R. acetosa by 49%, 19%, and 19% of the control. The root length of D. glomerata, L. perenne, and R. acetosa growing in the presence of 1.5 mM BOA and CA was decreased compared with the control. Both allelochemicals (BOA, CA) inhibited leaf osmotic potential (LOP) in L. perenne and D. glomerata. In L. perenne, Fv/Fm decreased after treatment with BOA (1.5 mM) while CA (1.5 mM) also significantly reduced Fv/Fm in L. perenne. Both allelochemicals decreased ΦPSII in D. glomerata and L. perenne within 24 h of treatment, while in R. acetosa, ΦPSII levels decreased by 72 h following treatment with BOA and CA. There was a decrease in qP and NPQ on the first, fourth, fifth, and sixth days after treatment with BOA in D. glomerata, while both allelochemicals reduced the qP level in R. acetosa. There was a gradual decrease in the fraction of light absorbed by PSII allocated to PSII photochemistry (P) in R. acetosa treated with BOA and CA. The P values in D. glomerata were reduced by both allelochemicals and the portion of absorbed photon energy that was thermally dissipated (D) in D. glomerata and L. perenne was decreased by BOA and CA. Photon energy absorbed by PSII antennae and trapped by ‘closed’ PSII reaction centres (E) was decreased after CA exposure in D. glomerata. BOA and CA (1.5 mM concentration) decreased the leaf protein contents in all three perennial species. This study provides new understanding of the physiological and biochemical mechanisms of action of BOA and CA in one perennial dicotyledon and two perennial grasses. The acquisition of such knowledge may ultimately provide a rational and scientific basis for the design of safe and effective herbicides.

Selection for monoculture and mixture genotypes in a biodiversity experiment

Studies in experimental grasslands have shown variation in plant individual performance in response to neighbourhood diversity. To which extent these responses are due to phenotypic plasticity or genetic variation is largely unknown. We collected seed families of five herbaceous species ( Cirsium oleraceum, Crepis biennis, Plantago lanceolata, Plantago media and Rumex acetosa) in monocultures and 60-species mixtures five years after establishment and replanted or transplanted the offspring into the same monocultures and 60-species mixtures. In all five species the actual environment significantly affected plant survival, growth and performance in terms of shoot biomass and investment into reproduction, indicating stronger competition for light and different levels of herbivory in mixtures as compared with monocultures. Effects of the original environment were smaller and less consistent, but indicated differential selection in monocultures vs. mixtures. The interaction between actual and original environment, corresponding to the “home” vs. “away” comparison, was rarely significant, yet this was providing a first sign of local adaptation. We conclude that, for the investigated plant species, more than five growing seasons in monocultures or mixtures would be needed to better demonstrate the selection of genotypes specifically adapted to monocultures or mixtures. A faster local adaptation may have been prevented by the ability of these species to respond to variation in neighbourhood diversity to a large degree via phenotypic plasticity and other factors.

Plant‐based fertilizers for organic vegetable production

AbstractTo ensure high yield and quality in organic vegetable production, crops often require additional fertilizer applied during the season. Due to the risk of contamination of edible plant products from slurry, plant‐based fertilizers may be used as an alternative. The purpose of our work was to develop mobile green manures with specific high nutrient concentrations (e.g., nitrogen [N], sulfur [S], and phosphorus [P]) that are released quickly after soil incorporation and that are easy to handle during storage and application. To distinguish from traditional green manures that are grown to improve soil fertility, the term “mobile green manures” is used for green‐manure crops that are harvested in one field and then moved as a whole and used as fertilizer in other fields. To further investigate mobile‐green‐manure crops for use as efficient fertilizers, pot and field experiments were conducted with cauliflower (Brassica oleracea botrytis) and kale (Brassica oleracea sabellica) supplied with organic matter consisting of a wide range of plant species with varying nutrient concentrations. Further, field experiments were conducted with leek (Allium porrum) and celery (Apium graveolens dulce) supplied with increasing amounts of organic matter consisting of fresh, ensiled, or dried green manures. Results show that garden sorrel (Rumex acetosa), dyer's woad (Isatis tinctoria), and fodder radish (Raphanus sativus) harvested with a high leaf‐to‐stem ratio resulted in high P concentration, and cruciferous crops in high S concentration. Dyer's woad, salad burnet (Sanguisorba minor), and stinging nettle (Urtica dioica) showed high boron (B) concentration, whereas species such as dandelion (Taraxacum officinale), chicory (Cichorium intybus), and garden sorrel showed high potassium (K) concentration. Green manures with high P and S concentrations increased the nutrient uptake and yield of pot‐grown cauliflower and kale. Field experiments showed that the production of cauliflower and kale decreased when the carbon‐to‐nitrogen (C : N) ratio of applied green manure increased. In kale, for example, application of 160 kg N ha–1 in early harvested lucerne (Medicago sativa) with a C : N ratio of 10 resulted in the highest kale production whereas application of an equal amount of N in late harvested lucerne with a C : N ratio of 20 produced 34% less. Differences in vegetable production were not due to the amount of N applied, but to the N availability. Field experiments with fresh, ensiled, or dry green manure applied to leek and celery showed that the C : N ratio has to be low to get a fast response. Further, these field experiments demonstrate the importance of green manures, which can be stored and are easy to handle during transport, crop application, and soil incorporation. It is concluded that it is possible to produce green manures with high concentrations of S, P, K, and B, and low C : N ratios and that these properties have a great impact on the value of the green manure for vegetable production.

Allelopathic potential of Acacia melanoxylon on the germination and root growth of native species

Water extracts that were obtained from the flowers and phyllodes of Acacia melanoxylon were used to determine their allelopathic potential in relation to the germination and seedling growth of the native species, cocksfoot (Dactylis glomerata), perennial ryegrass (Lolium perenne), and common sorrel (Rumex acetosa), as well as a general biotest specie, lettuce (Lactuca sativa), in laboratory bioassays. The flowers and phyllodes of A. melanoxylon were soaked separately in distilled water in a ratio of 1:1 (w/v) for 24 h in order to prepare the aqueous extracts. Distilled water was used as the control. The seeds of the target species were germinated in Petri dishes and counted daily for up to 7 days. The A. melanoxylon flower extract (100%, 75%, and 50%) decreased the seed germination of D. glomerata, R. acetosa, L. perenne, and L. sativa. The flower extract caused the most reduction in the germination index and germination speed in D. glomerata, L. perenne, and L. sativa. The mean LC50 value of the A. melanoxylon flower and phyllode extracts in relation to the germination inhibition of L. perenne was 43% and 41%, respectively, 40% and 38%, respectively, in R. acetosa, and 53% and 41%, respectively, in L. sativa. All four concentrations of the flower extract proved to be more phytotoxic than the phyllode extract, reducing the root length of all four species, while the phyllode extract decreased the root length of L. perenne and R. acetosa at the 100% concentration. The L. perenne and D. glomerata grass seeds were more sensitive regarding germination, as compared to L. sativa and R. acetosa. The flower aqueous extract of A. melanoxylon was more phytotoxic, as compared to the phyllode aqueous extract, even at the lowest concentration (25%).

A Study of Chromium, Cooper, and Lead Distribution from Lignite Fuels Using Cultivated and Non-cultivated Plants as Biological Monitors

Concentrations of chromium, copper, and lead were determined in soil and plant specimens collected from the area of coal power plant (CPP), A. Dimitrios, the largest CPP in Greece located on the eastern part of Ptolemais basin, Macedonia. Two cultivated plants (Brassica oleracea var. capitata L. and Zea mays L.) and two non-cultivated plants (Rumex acetosa L. and Verbascum phlomoides L.) were chosen. The mean heavy metal content in the soil is described in the descending order of Cr>Pb>Cu, while for the plant material, the order was Cr>Cu>Pb. Stations in the vicinity of the CPP showed a distinctly high load of Cr in the soil, whereas for the other metals, no such correlation has been noted. Unexpectedly, high levels of chromium and copper have been found in plant samples of the control station (Grevena) where there is no significant point source of air pollution by particulate matter. In general, roots revealed a higher metal concentration than that of the other plant organs. This is more obvious in B. oleracea var. capitata for all metals studied. Thus, B. oleracea var. capitata possesses the potential for phytoremediation of soils contaminated by metals since this plant is removable together with its roots from the contaminated soil. The most contaminated leaves showed a variation in surface roughness. In V. phlomoides the non-glandular, branched candelabrum-like trichomes on the leaf epidermis effectively trapped and retained a considerable number of particles. In contrast, the waxy cuticle of R. acetosa, which forms a smooth sheet over the epidermal cells, enabled the fast removal of particles by rain or wind. In the case of Z. mays, seeds accumulated the lowest amount of all metals.

Oligomeric proanthocyanidins from Rumex acetosa L. inhibit the attachment of herpes simplex virus type-1

The polyphenole-enriched acetone–water extract R2 from the aerial parts of Rumex acetosa L. containing high amounts of oligomeric and polymeric proanthocyanidins and flavonoids was tested for antiviral activity. R2 exhibited strong antiviral activity against herpes simplex virus type-1 (HSV-1) while the replication of adenovirus 3 was not affected. By plaque reduction test and MTT assay on Vero cells, the HSV-1-specific inhibitory concentration (IC 50) and cytotoxic concentration (CC 50) were determined. R2 exibited an IC 50 of 0.8 μg/mL and a selectivity index (SI) (ratio of IC 50 to CC 50) of approximately 100 when added to the virus inoculum for 1 h at 37 °C prior to infection. The antiviral activity was due to the presence of flavan-3-ols and oligomeric proanthocyanidins in the extract. Structure–activity analyses indicated that flavan-3-ols and proanthocyanidins with galloylation at position O-3 are highly potent compounds (SI > 40), while ungalloylated compounds did not exhibit antiviral effects (SI < 1). R2 and a major proanthocyanidin from R2, epicatechin-3-O-gallate-(4β → 8)-epicatechin-3-O-gallate abolished virus entry into the host cell by blocking attachment to the cell surface. When added after attachment at a concentration of ≥12.5 μg/mL, R2 inhibited also penetration of HSV-1 into the host cell. R2 and epicatechin-3-O-gallate-(4β → 8)-epicatechin-3-O-gallate were shown to directly interact with viral particles leading to the oligomerisation of envelope proteins as demonstrated for the essential viral glycoprotein gD. Using raft cultures with three-dimensional organotypic human skin equivalents it was shown that treatment of cultures with R2 after infection with HSV-1 resulted in a reduced viral spread.

Endogenous abscisic acid as a key switch for natural variation in flooding-induced shoot elongation.

Elongation of leaves and stem is a key trait for survival of terrestrial plants during shallow but prolonged floods that completely submerge the shoot. However, natural floods at different locations vary strongly in duration and depth, and, therefore, populations from these locations are subjected to different selection pressure, leading to intraspecific variation. Here, we identified the signal transduction component that causes response variation in shoot elongation among two accessions of the wetland plant Rumex palustris. These accessions differed 2-fold in petiole elongation rates upon submergence, with fast elongation found in a population from a river floodplain and slow elongation in plants from a lake bank. Fast petiole elongation under water consumes carbohydrates and depends on the (inter)action of the plant hormones ethylene, abscisic acid, and gibberellic acid. We found that carbohydrate levels and dynamics in shoots did not differ between the fast and slow elongating plants, but that the level of ethylene-regulated abscisic acid in petioles, and hence gibberellic acid responsiveness of these petioles explained the difference in shoot elongation upon submergence. Since this is the exact signal transduction level that also explains the variation in flooding-induced shoot elongation among plant species (namely, R. palustris and Rumex acetosa), we suggest that natural selection results in similar modification of regulatory pathways within and between species.

Pollen and non-pollen palynomorph evidence of medieval farming activities in southwestern Greenland

Radiocarbon dating, pollen and non-pollen palynomorph analyses from a lake core were used to establish the timing and effects of farming activities around Lake Igaliku, Eastern Settlement, Greenland. The absence of agro-pastoral impact before the medieval colonization by Europeans provides an opportunity to understand the development of farming activity in a pristine landscape. The results show that the first phase of clearance and grazing pressure, without the expansion of the Norse apophyte (native plant, in habitats created by humans) Rumex acetosa type, could have occurred in the 9–10th century a.d. The presence of Norse settlers and livestock is clearly recorded from the 11–12th century a.d. with increasing frequencies of the Norse apophytes Rumex acetosa type and Ranunculus acris type, and coprophilous fungi. This colonization phase is followed by a period of decreasing human impact at the beginning of the 14th century, with a decrease in weeds, apophytes and coprophilous fungi suggesting a reduced grazing pressure. The regrowth of Salix and Betula and the disappearance of anthropogenic indicators except Rumex acetosa type between the 15th and 18th century demonstrate the abandonment of the settlement, until the development of contemporary agriculture in the 20th century.

Host specificity of Euops chinesis, a potential biological control agent of Fallopia japonica, an invasive plant in Europe and North America

Fallopia japonica (Houttuyn) Ronse Decraene (Polygonaceae) is a serious invasive weed in North American and Europe. In its native China, a leaf-rolling weevil, Euops chinesis (Coleoptera: Attelabidae) was found attacking F. japonica in the field. No-choice tests, multiple-choice tests, open field tests and field surveys were conducted as a measure of its host specificity. Forty-six plant species were selected from 17 families for host range testing, among which, six species, F. multiflora, F. japonica, Persicaria perfoliata, Rumex acetosa, R. japonicus and R. aquaticus, were exposed to adults in no-choice tests. However, larvae could only develop successfully on F. japonica, and this plant appeared to be the only host in the field, suggesting the weevil is host-specific. As larval development appears to depend on a fungus in the leaf rolls, the insect–fungus mutualism and risks including host specificity of the fungus should be evaluated before the insect’s introduction.

Antifungal activity of extracts of some plants used in Brazilian traditional medicine against the pathogenic fungus Paracoccidioides brasiliensis

Paracoccidioidomycosis (PCM) is a systemic granulomatous disease caused by Paracoccidioides brasiliensis Almeida (Onygenales) that requires 1–2 years of treatment. In the absence of drug therapy, the disease is usually fatal, highlighting the need for the identification of safer, novel, and more effective antifungal compounds. With this need in mind, several plants employed in Brazilian traditional medicine were assayed on P. brasiliensis and murine macrophages. Extracts were prepared from 10 plant species: Inga spp. Mill. (Leguminosae), Schinus terebinthifolius Raddi (Anacardiaceae), Punica granatum L. (Punicaceae), Alternanthera brasiliana Kuntze (Amaranthaceae), Piper regnellii CDC. (Piperaceae), P. abutiloides Kunth (Piperaceae), Herissantia crispa L. Briz. (Malvaceae), Rubus urticaefolius Poir (Rosaceae), Rumex acetosa L. (Polygonaceae), and Baccharis dracunculifolia DC. (Asteraceae). Hexane fractions from hydroalcoholic extracts of Piper regnellii and Baccharis dracunculifolia were the most active against the fungus, displaying minimum inhibitory concentration (MIC) values of 7.8 μg/mL and 7.8–30 μg/mL, respectively. Additionally, neither of the extracts exhibited any apparent cytotoxic effects on murine macrophages at 20 μg/mL. Analyses of these fractions using gas chromatography-mass spectrometry (GC-MS) showed that the major components of B. dracunculifolia were ethyl hydrocinnamate (14.35%) and spathulenol (16.02%), while the major components of the hexane fraction of Piper regnellii were 1-methoxy-4-(1-propenyl) benzene (21.94%) and apiol (21.29%). The activities of these fractions against P. brasiliensis without evidence of cytotoxicity to macrophages justify their investigation as a potential source of new chemical agents for the treatment of PCM.

Differences in EDTA-assisted metal phytoextraction between metallicolous and non-metallicolous accessions of Rumex acetosa L.

Two common sorrel ( Rumex acetosa) accessions, one from a Zn–Pb contaminated site (CS accession) and the other from an uncontaminated site (UCS accession), were hydroponically exposed to a mixture of heavy metals (Pb 2+ + Zn 2+ + Cd 2+) with and without EDTA at an equimolar rate. The metallicolous CS accession showed a higher tolerance to metal treatment in the absence of the chelating agent, whereas the UCS accession was especially tolerant to EDTA treatment alone. Combination of metal and EDTA treatment resulted in a higher Pb accumulation in shoots of both accessions although plants hardly showed phytotoxic symptoms. Cd and Zn uptake was not augmented by EDTA addition to the polymetallic medium. Chelant-assisted Pb accumulation was 70% higher in the CS accession than in the UCS accession, despite the fact that the former accession evapotranspired less water than the UCS accession. These results support the existence of a non-selective apoplastic transport of metal chelates by R. acetosa roots, not related to transpiration stream.