Ranunculus Sceleratus Research Articles

Environmental Reservoirs for Enterotoxigenic Escherichia coli in South Asian Gangetic Riverine System

Forecasting diarrheagenic E. coli contamination of aquatic resources to prevent outbreaks largely depends on rapid and accurate diagnostic testing in a few hours. Real-time PCR is widely used for quick culture-free quantitative enumeration of pathogenic bacteria in environmental samples. In this study, real-time PCR in molecular beacon format was used for detection and culture-free quantitative enumeration of enterotoxigenic Escherichia coli (ETEC) harboring LT1 gene in a sewage-impacted south Asian Gangetic riverine system. The quantitative budget for ETEC in surface water was observed to vary significantly (DMRT, p < 0.05) among the sites. Aquatic flora (Eichhornia crassipes, Potamogeton crispus, Potamogeton pectinatus, Ranunculus sceleratus, Polygonum glabrum, Pontederia cordata, Najas indica and strands of Spirogyra spp.) collected between sites 1 and 9 exhibited significant high levels of ETEC in comparison to their representatives collected from pristine area. The level of ETEC harboring LT1 gene observed in leafy vegetables cultivated along the banks was in the following order: mint leaves > coriander > spinach > methi leaves. The study suggests that the aquatic flora and cultivated leafy vegetables in the south Asian Gangetic riverine system are environmental reservoirs for enterotoxigenic Escherichia coli.

Screening of weed extracts for antifungal properties againstColletotrichum lagenarium, the causal agent of anthracnose in cucumber

The antifungal activity of the leaf extracts from 203 weed species was investigated by performing a bioassay using cucumber plants and Colletotrichum orbiculare. The leaf extracts from four families, namely, Urticaceae, Onagraceae, Commelinaceae, and Solanaceae, showed a relatively stronger inhibition of the anthracnose lesions in cucumber plants when compared with the other families investigated in the study. A remarkable inhibition of anthracnose infection in cucumber leaves was observed with the extracts from the following 19 weed species: Boehmeria nipononivea and Boehmeria longispica, Persicaria scabra, Ranunculus japonicus and Ranunculus sceleratus, Cardamine flexuosa, Oenothera biennis, Aeschynomene indica, Indigofera pseudo-tinctoria, Torilis scabra, Calystegia japonica, Solanum americanum, Bidens pilosa, Gnaphalium japonicum, Kalimeris yomena, Bromus catharticus, Cynodon dactylon, Alopecurus aequalis, and Scirpus tabernaemontani. In particular, it is noteworthy that the extracts from C. dactylon, K. yomena, and S. americanum completely inhibited anthracnose infection in cucumber.

The potential role of waterbirds in dispersing invertebrates and plants in arid Australia

Summary1. The role of waterbirds as vectors of plants and invertebrates within and between arid‐zone wetlands is poorly understood. We present the first detailed study of passive dispersal by nomadic birds in Australasia. We investigated the numbers and types of invertebrate and plant propagules within freshly collected faecal samples as well as their viability. We compared dispersal among Grey Teal (Anas gracilis), Eurasian Coot (Fulica atra) and Black Swan (Cygnus atratus) in the Macquarie Marshes, a complex of temporary to semi‐permanent wetlands in New South Wales.2. When faecal samples (n = 60) were inundated in the laboratory and monitored over 3 weeks, ciliates (75% of samples), nematodes (22%), ostracods (13%) and rotifers (5%) were recorded, with higher taxon richness in coot samples. Faecal samples (n = 71) were also sieved to quantify intact propagules, and ostracod eggs (70% of samples), large branchiopod eggs (31%) and bryozoan statoblasts (31%) were the most abundant invertebrates. Diaspores of 19 plant taxa were recorded, 14 of which were germinated in the laboratory or shown to be viable at the end of germination trials. The abundance and diversity of invertebrate propagules was highest in coot samples, whereas the abundance and diversity of diaspores was highest in teal samples.3. One Australian Pelican (Pelecanus conspicillatus) sample was obtained and found to contain more taxa and far more propagules than any sample from other waterbirds, suggesting that piscivorous birds might have an important role in the indirect dispersal of propagules ingested by fish.4. Our results support a role for birds in explaining the distributions of cosmopolitan plant genera such as Lemna, Typha, Myriophyllum and Nitella. The alien plants Ranunculus sceleratus, Medicago polymorpha and Polygonum arenastrum were recorded, demonstrating the potential role of waterfowl in the spread of exotic species. As the frequency and duration of flooding of arid‐zone wetlands decreases owing to human activities, the importance of waterbirds in facilitating recolonisation of temporary wetlands is likely to increase.

Isothermal micro-calorimetry: a tool to predict seed longevity?

This paper describes the exploratory use of isothermal micro-calorimetry (IMC) to measure directly the heat flow produced as seeds age. Heat flow was recorded in primed and non-primed (control) seeds of Ranunculus sceleratus L., aged in a micro-calorimeter at 35°C at three different seed water contents [c. 0.12, 0.075 and 0.045 g H2O (g dw)−1]. The rate of heat flow and total heat generated (an indicator of extent of reaction) were generally greater in control seeds, which aged at a faster rate, than in primed seeds. Total heat generated over a given period also increased with increasing water content. The power–time curves did not indicate first- or second-order rate kinetics, consistent with the probability that seed ageing is complex and involves a number of reactions. Even after the capacity to germinate had ceased, there was a residual power signal. As a method, IMC gave consistent results using independent samples at different times. Therefore, short-term experiments at relatively high water contents and/or temperatures may have the potential to predict the relative longevity of seed-lots, at least within a species.

Evaluation of Antiviral Activity of Compounds Isolated fromRanunculus sieboldiiandRanunculus sceleratus

Nineteen compounds isolated from Ranunculus sieboldii and Ranunculus sceleratus were tested for inhibitory effects on hepatitis B virus (HBV) and Herpes simplex virus type-1 (HSV-1). The results showed that apigenin 4'- O- alpha-rhamnopyranoside, apigenin 7- O- beta-glucopyranosyl-4'- O- alpha-rhamnopyranoside, tricin 7- O- beta-glucopyranoside, tricin, and isoscopoletin possessed inhibitory activity against HBV replication. Protocatechuyl aldehyde exhibited an inhibiting activity on HSV-1 replication. It is therefore suggested that further investigations on these bioactive compounds might be needed to discover and develop new antiviral agents.

An experimental study on the growth and flowering of riparian pioneer plants under long- and short-day conditions

Plants of 19 annual taxa from the hygro-nitrophilous vegetation of Central European river banks and dried ponds were exposed as seedlings for 42 days to either natural long days (LD=ca. 15.5 h) or artificial short days (SD=11 h). Phenological and morphological growth parameters such as first flowering, main stem length, leaf size and plant dry weight were measured and compared. Based on their day-length responses, the plants were classified as 11 short-day plants (SDP), 6 long-day plants (LDP) and 2±day neutral plants (DNP). Differences of morphological plant responses under SD (compared with those under LD) reached from none to almost negligible ones in Ranunculus sceleratus, Bidens cernua, Chenopodium ficifolium and Rumex palustris to an extreme reduction in all parameters, as in Chenopodium glaucum× rubrum, Ch. rubrum, Ch. glaucum, Ch. polyspermum, Bidens radiata, Persicaria lapathifolia subsp. brittingeri and subsp. lapathifolia. Growth inhibition was usually combined with neotenic flowering in SDP. Some LDP exhibited clear dormancy responses, like the formation of smaller (winter) rosettes. Erosulate therophytes were mostly SDP while (hemi)rosulate to caespitose winter annuals or short-lived hemicryptophytes were LDP. Plants of seven species that were exposed to natural SD in spring (increasing day length) showed rather different responses. While Bidens radiata flowered in late spring soon after floral induction, other species showed increasing degrees of flowering delay ( Chenopodium polyspermum→ Xanthium saccharatum→ Chenopodium rubrum). Only Atriplex prostrata did not exhibit any sign of floral induction until (decreasing) SD in late summer arrived. In the case of Chenopodium rubrum details of the divergent morphogenesis under SD and LD were studied. In this species SD lead to strong reduction of stem length, leaf number and leaf size, simplification of leaf outline and margins as well as an enhanced ramification in the axils of primary leaves (and cotyledons) instead of metaphylls. The study reveals that for the phytosociological vegetation group Chenopodion rubri, whose populations are mainly confined to river banks with moist but well-aerated sediments, erosulate, therophytic and often neotenic SDP are typical. For the species of the Bidention – that thrive preferentially at the margins of stagnant water on rather wet soils – (hemi)rosulate or caespitose winter annuals are frequent. They are often LDP and survive the cold season in a vegetative state, even under a shallow level of water. The SD response of therophytic pioneers together with an often strong neotenic plasticity is interpreted here as a reassurance for the plants to flower and set seed in riparian habitats that are available for colonization only for a short and insecure period of the year, which due to the asymmetric position of annual low water levels in larger rivers is often not before mid-summer.

Ephemeral wetland vegetation in irregularly flooded arable fields along the northern Upper Rhine: the importance of persistent seedbanks

Along the northern Upper Rhine ephemeral wetland vegetation is not confined to primary habitats such as the fringes of backwaters and river banks, but is also found in irregularly flooded arable fields. Within these highly variable environments, where disturbance is not only by flooding but also by agricultural management, we assessed the role of seedbanks for the persistence of ephemeral vegetation. In order to achieve this, we analysed the floristic composition of the above-ground vegetation and the correspond- ing soil seedbank of arable fields after a long-lasting spring and early summer flood in 2001. Moreover, we compared our vegetation data with other phytosociological studies from primary and secondary habitats along the northern Upper Rhine. The comparison between primary and secondary habitats of mudflat species revealed differences in species composition. While primary habitats were characterised by the pre- dominance of species of Isoeto-Nanojuncetea and B identetea, secondary habitats contained additionally species of the classes Agrostietea and S tellarietea. The studied soil seedbanks were dominated by species typical of both, mudflat and agri- cultural habitats. Most species found in the seedbank were characterised by short life cycles and the ability to rapidly exploit periods of favourable conditions for germination and growth. The flooding treatments that were applied prior to the third season of seed- bank analysis almost generally resulted in a high proportion of additional germination of mudflat species, even two years after the start of the analysis. The emergence of some mudflat species such as Gnaphalium uliginosum, Veronica peregrina and semi-aquatic helophytes such as Alisma lanceolatum and A. plantago-aquatica was actually confined to the flooding treatment. Seed densities were exceptionally high and increased with the duration and frequency of inundation at the sampling sites. Juncus bufonius, Ranunculus sceleratus and Veronica catenata were the most abundant species. For Juncus bufonius we found a maximum seed density of 707,072 seeds m Ð2 , which is to our knowledge the highest seed concentration that was ever found in a higher plant. The large persistent soil seedbanks proved to be of outstanding importance for the emergence of ephemeral wetland vegetation after flood disturbances in arable fields. This was also reflected by the relatively high similarity be- tween the seedbank and the established vegetation directly after flooding. Our study highlights the importance of irregularly flooded arable fields as a secondary habitat for the conservation of ephemeral wetland species. At these sites, not only im- proved drainage and landfill threatens the occurrence of mudflat vegetation but also the replenishment of the seedbank is often prevented by early re-ploughing of the fields.

침수에 의한 식물의 생장 촉진과 호르몬들의 작용 네트워크

하천변에 사는 식물들은 침수 저항성을 갖추고 있는데 그중 Ranunculus속이나 Rumex속에 속하는 일부 반수생 식물들에서 볼 수 있는 것처럼, 엽병이 급격한 생장을 일으켜 잎이 수표면에 이르게 함으로써 호흡할 수 있는 조건을 확보하는 현상은 식물체내에 축적된 에틸렌에 의하여 매개되는 현상이다. 침수 조건에서는 식물 조직 내에 에틸렌이 축적되며, 축적된 에틸렌은 옥신 등 다른 식물호르몬에 대한 조직의 감수성을 증가시켜 생장을 촉진한다. 증가된 생장으로 잎이 수표면에 이르게 되면 다시 공기를 접촉하여 호흡할 수 있게 되고, 식물체내에 축적되었던 에틸렌은 대기 중으로 확산하여 나가게 되므로 체내 에틸렌 농도가 감소하여 생장률이 침수 이전 수준으로 되돌아간다. 에틸렌에 의한 옥신의 감수성 증가는 선량 반응 곡선에 비추어 수용체의 친화도 증가가 수반되는 것으로 생각되는데, 아직 옥신 수용체가 밝혀지지 않아 분자생물학적 기작은 연구되어야 할 과제로 남아있다. 최근 옥신 수용체 발견의 가능성이 높아지고 있으며, 따라서 에틸렌에 의한 옥신 수용체의 옥신에 대한 감수성 조절기작을 탐구할 수 있는 길이 열릴 것으로 기대된다. Plants living riverside show diverse resistance responses to submergence. The promoted petiole elongation of semi-aquaitc plants, e.g., such as Ranunculus sceleratus and Rumex palustris, is one of the adaptive responses mediated by the plant hormone ethylene. The gaseous hormone is trapped in submerged plant tissues and enhances the petiole growth by increasing sensitivity of the tissues to some plant hormones including auxin. Due to the stimulated growth of petioles, the leaves finally reach the water surface and can respirate again. At the water surface, the accumulated ethylene diffuses out from the tissues to the air. As a result, the increased hormone sensitivity decreases again, and thus the growth rate reduces to the basal level as before. The increased auxin sensitivities by ethylene observed in Ranunculus sceleratus, revealed by the changes in the auxin dose-response curves, indicate the increase of affinities of the receptors to auxin. However, the molecular mechanism of the affinity regulation remains still largely unknown, because the identity of the auxin receptor is still unclear.

Effects of Natural Products on Contact Dermatitis

Some medicinal plants, which are known to produce allergic reactions, are also specifically used as antiinflammatory agents. Among the more relevant plants, we report species with cinnamaldehyde, cinnamic alcohol, geraniol, hydroxycitronellal, eugenol and isoeugenol are all potential allergens. In addition, fragrances, which are mixtures of small-molecular-weight compounds, may induce allergic contact dermatitis due to fragrance-specific CD4+ and CD8+ T lymphocytes. Plants from the Asteraceae family used in folk medicine as anti-inflammatories can cause allergic contact dermatitis because of its content in sesquiterpene lactones, which have been reported as the antiinflammatory principles in this species. Species with flavonoids, iridoids, terpenoids and alkaloids have been described as inhibitors of contact dermatitis. Scrophularia auriculata, Poria cocos, Santolina chamaecyparissus, Ranunculus sceleratus and Helichrysum italicum all showed activity in different experimental protocols of contact dermatitis, thus justifying the potential use of these medicinal plants as anti-allergens and inhibitors of contact dermatitis reactions produced by allergens and chemicals. Hydroquinone derivatives such as 1-O-b-glucopyranosyl-2-(3-hydroxymethyl-3-methylallyl) hydroquinone and arbutin, flavonoids such as kaempferol, apigenin and genistein, sesquiterpene lactones such as helenalin, diterpenes such as triptonide, triterpenes such as tripterine and bryonolic acid, iridoids such as scrovalentinoside, alkaloids such as indirubin, dehydrocorydaline, magnoflorine hydroxide and phellodendrine acetate, and polysaccharides such as fucoidin have been reported as inhibitors of contact dermatitis reactions.

Pharmacological approach to the pro- and anti-inflammatory effects of Ranunculus sceleratus L.

Ranunculus sceleratus is a widespread species with unique toxicological and pharmacological activities. The present study seeks to assess this species’ ability, both in vitro and in vivo, to modulate processes involved in inflammations. To this end, different extracts from the aerial parts of the plant were tested in several models of acute inflammation induced by tetradecanoylphorbol acetate (TPA), arachidonic acid (AA), and carrageenan, as well as in two models of delayed hypersensitivity induced by oxazolone and dinitrofluorobencene (DNFB). The extracts were also assayed in models of eicosanoid and elastase release by intact cells. When tested in vivo, all of the extracts showed anti-inflammatory or neutral effects. In vitro, non-polar extracts of this species were able to inhibit eicosanoid production, whereas polar extracts enhanced the synthesis of 5( S)-HETE, LTB 4 and 12( S)-HHTrE. The hypothesis of a “counter-irritant” mechanism of action has thus been proposed and is also discussed herein.

Inhibition of Trypanosoma cruzi growth by medical plant extracts

This study describes the screening of extracts obtained from 18 plants and two fungi used in the Chinese and Mediterranean traditional medicines on epimastigote forms of Trypanosoma cruzi. The extracts were tested against epimastigote of T. cruzi Bra C15C2 clone in vitro at 27 °C and at a concentration of 250 μg/ml in axenic culture. Angelica dahurica, A. pubescens, A. sinensis, Astragalus membranaceus, Coptis chinensis, Haplophyllum hispanicum, Phellodendron amurense, Poria cocos, Ranunculus sceleratus and Scutellaria baicalensis showed significant effects against the parasite with a percentage of growth inhibition between 20 and 100%. C. chinensis and R. sceleratus showed the greatest activity with IC 50 values of 1.7 μg/ml for C. chinensis and 10.7 μg/ml for R. sceleratus. These activities are greater than that of allopurinol. C. chinesis and R. sceleratus extracts did not show cytotoxic effects on rat polimorphonuclear cells using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide and lactic dehydrogenase assays. These results allowed us to suggest that R. sceleratus and C. chinensis could be a source of new compounds clinically active against T. cruzi.

Changes in growth, porosity, and radial oxygen loss from adventitious roots of selected mono‐ and dicotyledonous wetland species with contrasting types of aerenchyma

ABSTRACTGrowth in stagnant, oxygen‐deficient nutrient solution increased porosity in adventitious roots of two monocotyledonous (Carex acuta and Juncus effusus) and three dicotyledonous species (Caltha palustris, Ranunculus sceleratus and Rumex palustris) wetland species from 10 to 30% under aerated conditions to 20–45%. The spatial patterns of radial oxygen loss (ROL), determined with root‐sleeving oxygen electrodes, indicated a strong constitutive ‘barrier’ to ROL in the basal root zones of the two monocotyledonous species. In contrast, roots of the dicotyledonous species showed no significant ‘barrier’ to ROL when grown in aerated solution, and only a partial ‘barrier’ when grown in stagnant conditions. This partial ‘barrier’ was strongest in C. palustris, so that ROL from basal zones of roots of R. sceleratus and R. palustris was substantial when compared to the monocotyledonous species. ROL from the basal zones would decrease longitudinal diffusion of oxygen to the root apex, and therefore limit the maximum penetration depth of these roots into anaerobic soil. Further studies of a larger number of dicotyledonous wetland species from a range of substrates are required to elucidate the ecophysiological consequences of developing a partial, rather than a strong, ‘barrier’ to ROL.

Phylogenetic variability in the pigment complement of aquatic tracheophytes

The pigment complements of five emergent aquatic tracheophyte species were analyzed using high performance liquid chromatography. The species were chosen to represent major taxa and included Equisetum palustre L., a pteridophyte; Glyceria fluitans (L.) Robert Brown, a monocot; and three dicots, Callitriche sp., Veronica beccabunga L., and Ranunculus sceleratus L. The samples had been taken from the same site on the same date and time of day. Cluster analysis of the results for each sample revealed that several of the species are distinct from the others in the quantitative composition of their pigment complements. However, these distinctions do not reflect phylogenetic differences among the major taxa. It is concluded that differences in the chloroplast genomes that have been used to trace the phylogenetic development of the plants are not reflected in the phenotypic characteristics of the pigment complement.

Changes in Endogenous Levels of Free Polyamines during Petiole Elongation in the Semiaquatic Plant Ranunculus sceleratus

We investigated the relationships between polyamines and indole‐3‐acetic acid‐ (IAA) and ethylene‐induced petiole elongation in Ranunculus sceleratus. When applied exogenously, polyamines inhibited IAA‐induced petiole elongation in the presence or absence of ethylene. An inhibitor of arginine decarboxylase, α‐difluoromethylarginine, stimulated IAA‐induced petiole growth. IAA, ethylene, and fusicoccin all caused decreases in levels of endogenous spermine and other polyamine(s) (spermidine or putrescine or both). According to our kinetic studies, IAA and ethylene induced changes in endogenous polyamine contents at late stages of petiole elongation. Based on these results, we conclude that polyamines are involved in the regulation of IAA‐ and ethylene‐induced growth, especially in late stages of petiole elongation in Ranunculus.

Screening of antiinflammatory medicinal plants used in traditional medicine against skin diseases

The antiinflammatory activity of twelve medicinal plants used against skin disorders were tested in different experimental models of topical inflammation and one in vitro inhibitory test against phospholipase A2 (PLA2) from Naja naja venom. Forsythia suspensa was the most active species on the arachidonic acid (AA) topical test. This last species together with Astragalus membranaceus and Ranunculus sceleratus were the most active on the 12-O-tetradecanoylphorbol-13-acetate (TPA) acute ear oedema test. Scrophularia auriculata was the most active on multiple topical applications of TPA and on the oxazolone-induced delayed type hypersensitivity (DTH). Santolina chamaecyparissus was the only species that inhibited PLA2in vitro. © 1998 John Wiley & Sons, Ltd.

The contrasting role of auxin in submergence‐induced petiole elongation in two species from frequently flooded wetlands

The involvement of auxin in the submergence‐induced petiole elongation has been investigated in Rumex palustris and Ranunculus sceleratus. Both wetland species are capable of enhanced petiole elongation upon submergence or treatment with exogenous ethylene (5μl l−1). Treatment of intact Rumex palustris plants with 1‐naphthalene acetic acid (NAA) at 10−4M enhanced petiole elongation, while treatment with N‐1‐naphthylphthalamic acid (NPA) had no effect on petiole elongation. The elongation response after NAA or NPA treatment was comparable for plants in both submerged and drained conditions. Pre‐ageing of detached petioles of Rumex palustris for 3 h in light or in dark conditions had no effect on the submergence‐induced elongation. In comparison to intact plants, detached petioles of Rumex palustris, with or without lamina, did not show significant differences in responsiveness to IAA between drained or submerged conditions. This was in contrast to Ranunculus sceleratus where submergence caused a clear increase in responsiveness towards IAA. Removal of the lamina, the putative source of auxin, or treatment with NPA did not hinder the submergence‐induced elongation of detached Rumex palustris petioles, but severely inhibited elongation of detached Ranunculus sceleratus petioles. This inhibition could be restored by application of NAA, suggesting the specific involvement of auxin in the submergence response of Ranunculus sceleratus. It is concluded that, in contrast to Ranunculus sceleratus, auxin is probably not involved in the submergence‐induced petiole elongation of Rumex palustris.

Expression of ‘dehydrin-like’ proteins in orthodox seeds ofRanunculus sceleratusduring development and water stress

AbstractWestern blot analysis using antiserum raised against the lysine-rich box common to dehydrins, one class of late-embryogenesis-abundant (LEA) proteins, was used to study the abundance of heat-stable ‘dehydrin-like’ proteins during development and water stress inRanunculus sceleratusL. achenes (seeds). A 61 kDa dehydrin-like protein was apparently limited to immature seeds (fresh and dried) which had not attained full desiccation tolerance. In contrast, lower-molecular-mass proteins which were induced by desiccation were found only in more mature seeds. The molecular masses of desiccation-induced proteins changed during seed development from 18 kDa in seeds harvested at 13 days post anthesis (DPA) to 31 kDa at harvest maturity, 21 DPA.Placing seeds at 21 DPA in polyethylene glycol (PEG) at −1.5 MPa reduced seed moisture content and was accompanied by accumulation of 31 kDa protein. This protein was no longer detected when the seeds were transferred to water. In seeds harvested at 13 DPA, PEG induced the synthesis not only of 18 kDa protein (which is associated with dried seeds at this developmental stage), but also of 28 kDa and 31 kDa proteins. These dehydrin-like proteins were also synthesised when seeds at 13 DPA were imbibed in water. These and other data indicate that both quantitative and qualitative changes in dehydrin-like proteins can occur inR. sceleratus, depending on seed maturity and the degree and duration of water stress.

The ultrastructure of seed coat development inRanunculus sceleratus

Seed-coat development in Ranunculus sceleratus L. has been studied by electron microscopy. Three layers developed from the single integument. The outer epidermis consisted of elongated and flattened cells that were always well attached to each other. The cells were characterized by thin walls, the presence of chloroplasts and small vacuoles. The cells of the middle layer were originally closely packed. Gradually, extensive intercellular spaces were formed. The cells of the inner epidermis elongated initially, until they became cubic and developed a thick wall with numerous wall ingrowths at the side bordering the nucellus. Thus, they give rise to a mechanical layer protecting the inner part of the seed. The elongation of cells, the thickening of cell walls, the formation of wall ridges, and the formation of intercellular spaces each coincided with characteristic configurations of microtubules. Plasmodesmata were originally found between all cells of the integument but their number decreased drastically during development, especially between the three developing seed-coat layers. Well-differentiated chloroamyloplasts, present in all cells of the developing seed-coat, pointed to autotrophy during development. Maturation eventually led to the disappearance of cytoplasm in all cells, the compression of the cells of the outer epidermis and middle layers, and the formation of a mechanical layer from the inner epidermis.

The relationship between ‘dehydrin-like’ proteins and seed longevity inRanunculus sceleratusL.

The relationship between the abundance of proteins homologous to the dehydrin/RAB group of LEAs and seed longevity has been studied in Ranuncufus sceleratus L. The presence of these «dehydrin-like» proteins was not related to increases in seed longevity associated with seed development or priming treatments. Similarly, a drying-induced increase in the amount of «dehydrin-like» proteins was not accompanied by an improvement in longevity

Peroxidase, Ethylene, and Submergence-Promoted Growth of Petioles of Ranunculus sceleratus L.

Summary The distal 20 mm segments of petioles of intact Ranunculus sceleratus L. plants elongate after submergence. This growth is most pronounced in petioles of recently fully-expanded leaves. Initial peroxidase activities were lower in petioles that had a greater capacity to elongate under water, and lower activities were maintained during submergence. For isolated leaves, submergence or treatment with ethylene in air promoted growth of the petioles and the maintenance of low tissue-peroxidase levels. Petioles of isolated leaves, held with their blades in air or floating at the water/air interface, grow to a small extent but have very high levels of extractable peroxidase activity.