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PubMed2003

Interactions between plant hormones regulate submergence-induced shoot elongation in the flooding-tolerant dicot Rumex palustris.

Rumex palustris has the capacity to respond to complete submergence with hyponastic (upward) growth and stimulated elongation of petioles. These adaptive responses allow survival of this plant in habitats with sustained high water levels by re-establishing contact with the aerial environment. Accumulated ethylene in submerged petioles interacts with ethylene receptor proteins and operates as a reliable sensor for the under-water environment. Further downstream in the transduction pathway, a fast and substantial decrease of the endogenous abscisic acid concentration and a certain threshold level of endogenous auxin and gibberellin are required for hyponastic growth and petiole elongation. Interactions of these plant hormones results in a significant increase of the in vitro cell wall extensibility in submerged petioles. Furthermore, the pattern of transcript accumulation of a R. palustris alpha-expansin gene correlated with the pattern of petiole elongation upon submergence.

Adaptation, Physiological↗
PubMed2005

RP-ACS1, a flooding-induced 1-aminocyclopropane-1-carboxylate synthase gene of Rumex palustris, is involved in rhythmic ethylene production.

Many semi-aquatic plants respond to flooding by elongating the shoot to reach the water surface. This response is initiated by accumulation of ethylene in the plant due to decreased gas-exchange and continued ethylene production during submergence. Ethylene biosynthesis is often limited by the availability of 1-aminocyclopropane-1-carboxylic acid (ACC), the precursor of ethylene, synthesized by ACC synthase. Here, is reported the cloning of a Rumex palustris cDNA corresponding to an ACC synthase gene (RP-ACS1), whose expression is induced by submergence in the long term but does not precede the observed short-term increase in ACS activity. Under aerated conditions, RP-ACS1 messenger accumulation exhibited circadian rhythmicity with high levels in the dark phase and low levels in the light phase, similar to the oscillations in ethylene production under these conditions. ACC oxidase (RP-ACO1) messenger accumulation also showed a rhythmic pattern, but opposite to that of RP-ACS1, and closely resembled the ethylene oscillation found in R. palustris plants that were waterlogged. Together the results indicate that transcriptional regulation of RP-ACS1 may directly control rhythmic ethylene production under aerated condition and suggest that post-transcriptional regulation is important in initial up-regulation of ACS activity upon submergence.

Circadian Rhythm↗
PubMed2005

Photosynthetic consequences of phenotypic plasticity in response to submergence: Rumex palustris as a case study.

Survival and growth of terrestrial plants is negatively affected by complete submergence. This is mainly the result of hampered gas exchange between plants and their environment, since gas diffusion is severely reduced in water compared with air, resulting in O2 deficits which limit aerobic respiration. The continuation of photosynthesis could probably alleviate submergence-stress in terrestrial plants, but its potential under water will be limited as the availability of CO2 is hampered. Several submerged terrestrial plant species, however, express plastic responses of the shoot which may reduce gas diffusion resistance and enhance benefits from underwater photosynthesis. In particular, the plasticity of the flooding-tolerant terrestrial species Rumex palustris turned out to be remarkable, making it a model species suitable for the study of these responses. During submergence, the morphology and anatomy of newly developed leaves changed: 'aquatic' leaves were thinner and had thinner cuticles. As a consequence, internal O2 concentrations and underwater CO2 assimilation rates were higher at the prevailing low CO2 concentrations in water. Compared with heterophyllous amphibious plant species, underwater photosynthesis rates of terrestrial plants may be very limited, but the effects of underwater photosynthesis on underwater survival are impressive. A combination of recently published data allowed quantification of the magnitude of the acclimation response in this species. Gas diffusion resistance in terrestrial leaves underwater was about 15,000 times higher than in air. Strikingly, acclimation to submergence reduced this factor to 400, indicating that acclimated leaves of R. palustris had an approximately 40 times lower gas diffusion resistance than non-acclimated ones.

Acclimatization↗
PubMed2003

Plant movement. Submergence-induced petiole elongation in Rumex palustris depends on hyponastic growth.

The submergence-tolerant species Rumex palustris (Sm.) responds to complete submergence by an increase in petiole angle with the horizontal. This hyponastic growth, in combination with stimulated elongation of the petiole, can bring the leaf tips above the water surface, thus restoring gas exchange and enabling survival. Using a computerized digital camera set-up the kinetics of this hyponastic petiole movement and stimulated petiole elongation were studied. The hyponastic growth is a relatively rapid process that starts after a lag phase of 1.5 to 3 h and is completed after 6 to 7 h. The kinetics of hyponastic growth depend on the initial angle of the petiole at the time of submergence, a factor showing considerable seasonal variation. For example, lower petiole angles at the time of submergence result in a shorter lag phase for hyponastic growth. This dependency of the hyponastic growth kinetics can be mimicked by experimentally manipulating the petiole angle at the time of submergence. Stimulated petiole elongation in response to complete submergence also shows kinetics that are dependent on the petiole angle at the time of submergence, with lower initial petiole angles resulting in a longer lag phase for petiole elongation. Angle manipulation experiments show that stimulated petiole elongation can only start when the petiole has reached an angle of 40 degrees to 50 degrees. The petiole can reach this "critical angle" for stimulated petiole elongation by the process of hyponastic growth. This research shows a functional dependency of one response to submergence in R. palustris (stimulated petiole elongation) on another response (hyponastic petiole growth), because petiole elongation can only contribute to the leaf reaching the water surface when the petiole has a more or less upright position.

Adaptation, Physiological↗
PubMed2004

The roles of ethylene, auxin, abscisic acid, and gibberellin in the hyponastic growth of submerged Rumex palustris petioles.

Rumex palustris responds to complete submergence with upward movement of the younger petioles. This so-called hyponastic response, in combination with stimulated petiole elongation, brings the leaf blade above the water surface and restores contact with the atmosphere. We made a detailed study of this differential growth process, encompassing the complete range of the known signal transduction pathway: from the cellular localization of differential growth, to the hormonal regulation, and the possible involvement of a cell wall loosening protein (expansin) as a downstream target. We show that hyponastic growth is caused by differential cell elongation across the petiole base, with cells on the abaxial (lower) surface elongating faster than cells on the adaxial (upper) surface. Pharmacological studies and endogenous hormone measurements revealed that ethylene, auxin, abscisic acid (ABA), and gibberellin regulate different and sometimes overlapping stages of hyponastic growth. Initiation of hyponastic growth and (maintenance of) the maximum petiole angle are regulated by ethylene, ABA, and auxin, whereas the speed of the response is influenced by ethylene, ABA, and gibberellin. We found that a submergence-induced differential redistribution of endogenous indole-3-acetic acid in the petiole base could play a role in maintenance of the response, but not in the onset of hyponastic growth. Since submergence does not induce a differential expression of expansins across the petiole base, it is unlikely that this cell wall loosening protein is the downstream target for the hormones that regulate the differential cell elongation leading to submergence-induced hyponastic growth in R. palustris.

Abscisic Acid↗
PubMed2006

Long-term submergence-induced elongation in Rumex palustris requires abscisic acid-dependent biosynthesis of gibberellin1.

Rumex palustris (polygonceae) responds to complete submergence with enhanced elongation of its youngest petioles. This process requires the presence of gibberellin (GA) and is associated with an increase in the concentration of GA1 in elongating petioles. We have examined how GA biosynthesis was regulated in submerged plants. Therefore, cDNAs encoding GA-biosynthetic enzymes GA 20-oxidase and GA 3-oxidase, and the GA-deactivating enzyme GA 2-oxidase were cloned from R. palustris and the kinetics of transcription of the corresponding genes was determined during a 24 h submergence period. The submergence-induced elongation response could be separated into several phases: (1) during the first phase of 4 h, petiole elongation was insensitive to GA; (2) from 4 to 6 h onward growth was limited by GA; and (3) from 15 h onward underwater elongation was dependent, but not limited by GA. Submergence induced an increase of GA1 concentration, as well as enhanced transcript levels of RpGA3ox1. Exogenous abscisic acid repressed the transcript levels of RpGA20ox1 and RpGA3ox1 and thus inhibited the submergence-induced increase in GA1. Abscisic acid had no effect on the tissue responsiveness to GA.

Abscisic Acid↗
PubMed2006

Inhibitory effects of Rumex japonicus Houtt. on the development of atopic dermatitis-like skin lesions in NC/Nga mice.

BACKGROUND: Rumex japonicus Houtt. (RJH) is one of the herbs used in Eastern countries for the treatment of atopic dermatitis (AD). It has been shown to have an antioxidative effect in human skin disease. OBJECTIVES: To examine whether RJH extract (RJH-E) suppresses the development of AD-like skin lesions in NC/Nga mice, which are induced by the repeated application of picryl chloride (PC). METHODS: The efficacy of RJH-E in NC/Nga mice was assessed by measuring symptom severity, scratching behaviour, Staphylococcus aureus numbers on an ear, and serum levels of IgE, interleukin (IL)-4 and interferon (IFN)-gamma. RESULTS: Oral administration of RJH-E to NC/Nga mice treated with PC inhibited the development of AD-like skin lesions as exemplified by a significant decrease in total skin symptom severity scores, and a decrease in hypertrophy, hyperkeratosis and infiltration of inflammatory cells in the skin. The scratching behaviour and numbers of S. aureus, which are known to be exacerbated in AD, were also significantly reduced by RJH-E. No significant change was observed in the serum levels of IFN-gamma, whereas IgE and IL-4 levels were significantly reduced by RJH-E. CONCLUSIONS: These results suggest that RJH-E inhibits the development of AD-like skin lesions in NC/Nga mice by suppressing the T-helper 2 cell response. Our results indicate that RJH treatment could provide an effective alternative therapy for the management of AD.

Animals↗
PubMed2006

The stimulating effects of ethylene and auxin on petiole elongation and on hyponastic curvature are independent processes in submerged Rumex palustris.

The flooding-tolerant plant species Rumex palustris (Sm.) responds to complete submergence with stimulation of petiole elongation mediated by the gaseous hormone ethylene. We examined the involvement of auxin in petiole elongation. The manipulation of petiolar auxin levels by removing the leaf blade, or by addition of synthetic auxins or auxin transport inhibitors, led to the finding that auxin plays an important role in submergence-induced petiole elongation in R. palustris. A detailed kinetic analysis revealed a transient effect of removing the auxin source (leaf blade), explaining why earlier studies in which less frequent measurements were taken failed to identify any role for auxin in petiole elongation. We previously showed that the onset of stimulated petiole elongation depends on a more upright petiole angle being reached by means of hyponastic (upward) curvature, a differential growth process that is also regulated by ethylene and auxin. This raised the possibility that both ethylene and auxin stimulate elongation only indirectly by influencing hyponastic growth. We show here that the action of ethylene and auxin in promoting petiole elongation in submerged R. palustris is independent of the promoting effect that these hormones also exert on the hyponastic curvature of the same petiole.

Amino Acids, Cyclic↗
PubMed2005

Ethylene regulates fast apoplastic acidification and expansin A transcription during submergence-induced petiole elongation in Rumex palustris.

The semi-aquatic dicot Rumex palustris responds to complete submergence by enhanced elongation of young petioles. This elongation of petiole cells brings leaf blades above the water surface, thus reinstating gas exchange with the atmosphere and increasing survival in flood-prone environments. We already know that an enhanced internal level of the gaseous hormone ethylene is the primary signal for underwater escape in R. palustris. Further downstream, concentration changes in abscisic acid (ABA), gibberellin (GA) and auxin are required to gain fast cell elongation under water. A prerequisite for cell elongation in general is cell wall loosening mediated by proteins such as expansins. Expansin genes might, therefore, be important target genes in submergence-induced and plant hormone-mediated petiole elongation. To test this hypothesis we have studied the identity, kinetics and regulation of expansin A mRNA abundance and protein activity, as well as examined pH changes in cell walls associated with this adaptive growth. We found a novel role of ethylene in triggering two processes affecting cell wall loosening during submergence-induced petiole elongation. First, ethylene was shown to promote fast net H(+) extrusion, leading to apoplastic acidification. Secondly, ethylene upregulates one expansin A gene (RpEXPA1), as measured with real-time RT-PCR, out of a group of 13 R. palustris expansin A genes tested. Furthermore, a significant accumulation of expansin proteins belonging to the same size class as RpEXPA1, as well as a strong increase in expansin activity, were apparent within 4-6 h of submergence. Regulation of RpEXPA1 transcript levels depends on ethylene action and not on GA and ABA, demonstrating that ethylene evokes at least three, parallel operating pathways that, when integrated at the whole petiole level, lead to coordinated underwater elongation. The first pathway involves ethylene-modulated changes in ABA and GA, these acting on as yet unknown downstream components, whereas the second and third routes encompass ethylene-induced apoplastic acidification and ethylene-induced RpEXPA1 upregulation.

Abscisic Acid↗
PubMed2005

Intersex inflorescences of Rumex acetosa demonstrate that sex determination is unique to each flower.

* A triploid intersex individual of the normally dioecious species Rumex acetosa showed extreme variability in gynoecium development. Analysis of the development and distribution of these flowers on inflorescences enabled insight to be gained into the mechanism of sex determination. * Floral phenotypes on intersex inflorescences were classified according to gynoecium development. Flower morphology was investigated by scanning electron and light microscopy. Organ identity gene expression in intersex floral primordia was assessed using in situ hybridization. * The distribution of the different floral phenotypes shows that each individual flower is determined separately, and that the phenotype of each flower is not influenced by its position on the inflorescence, or by the phenotype of neighbouring flowers. C-function gene expression persisted in gynoecia that had ceased development. * Gynoecium development in mutant flowers resembled the phenotype of the Arabidopsis mutant ettin and suggests that a hormone gradient may be involved. C-function expression does not appear to control the extent of female development, and indicates that genes which are downstream of the organ-identity genes must control organ suppression.

Chromosomes, Plant↗
PubMed2006

Limited costs of wrong root placement in Rumex palustris in heterogeneous soils.

Nutrient hot spots in the soil have a limited life span, but the costs and benefits for root foraging are still underexposed. We assessed short-term costs that may arise when a nutrient-rich patch induces root proliferation, but then rapidly disappears. Rumex palustris plants were grown with a homogeneous or a heterogeneous nutrient application. After root proliferation in a nutrient-rich patch, nutrient supply was switched from homogeneous to heterogeneous, and vice versa, or the patch location was changed. R. palustris proliferated its roots in the rich patch. After switching, the relative growth rates of the roots were adjusted to the novel pattern of nutrient availability. However, the changes in local root biomass lagged behind the rapid shift in nutrient supply, because the root mass realized in specific sectors could not be rapidly relocated. Despite this, R. palustris did not exhibit costs of switching in terms of biomass or nitrogen uptake. Our data suggest that rapid shifts in uptake rate and redistribution of nitrogen within the plant may have lowered the costs of incorrect root placement.

Biomass↗
PubMed2005

Antimutagenicity and cytotoxicity of the constituents from the aerial parts of Rumex acetosa.

Four anthraquinones isolated for the first time from the aerial parts of Rumex acetosa (Polygonaceae), a Korean and a Japanese medicinal plant, and two synthetic derivatives were examined for their cytotoxicities against five cultured human tumor cell lines, i.e. A549 (non-small cell lung), SK-OV-3 (ovary), SK-MEL-2 (melanoma), XF498 (central nerve system) and HCY15 (colon), using the Sulfrhodamine-B method in vitro and antimutagenic activities by Ames test with Salmonella typhimurium TA98 and TA100 and SOS chromotest with E. coli PQ37. Among the tested compounds, emodin strongly inhibited the proliferation of each examined tumor cell line with IC50 values ranged from 2.94 to 3.64 microg/ml and showed potent antimutagenic activities with 71.5% and 53.3% at the concentration of 0.1 mg/plate against the mutagens, NPD and sodium azide, respectively. Its antigenotoxic activity was also very effective at the final concentration of 10 microg/reaction tube against the mutagens, MNNG and NQO by SOS chromotest, reducing the induction factors by 19.6% and 43.5%, respectively. The structure-activity correlation study suggests that an additional OH group at C-6 position in the anthraquinone nucleus may play an important role for their cytotoxicities and an introduction of OH- or OCH3 group at C-6 position is necessary for their antimutagenicities.

Animals↗
PubMed2005

Antioxidant and antibacterial activities of Rumex japonicus HOUTT. Aerial parts.

We evaluated total phenolic content, antioxidant activity, reducing power and antibacterial activity of ethanol, hexane, chloroform, ethyl acetate and aqueous extracts of aerial parts of Rumex japonicus HOUTT. The ethyl acetate extract had the highest amount of phenolic compounds. It also exhibited the highest reducing power and antioxidant activity when assayed by the 1,1-diphenyl-2-picrylhydrazyl (DPPH), beta-carotene bleaching and superoxide radical methods. The ethyl acetate extract possessed the strongest antibacterial activity against Bacillus subtilis, B. cereus and E. coli. GC-MS analysis indicated that ethyl acetate extract contained a variety of phenolic compounds. HPLC analysis showed that pyrogallol was the predominant phenolic compound in this extract. Thus, our study verified that the ethyl acetate extract has strong antioxidant and antibacterial activities which are correlated with its high level of phenolic compounds, particularly pyrogallol and pyrocatechin. This extract of R. japonicus aerial parts can be utilized as an effective and safe source of antioxidants.

Acetates↗
PubMed2005

24-nor-Ursane type triterpenoids from the stems of Rumex japonicus.

Fractionation of an EtOAc-soluble extract of the stems of Rumex japonicus led to the isolation of two new 24-norursane type triterpenoids, 2alpha,3alpha,19alpha-trihydroxy-24-norurs-4(23),12-dien-28-oic acid (1) and 4(R),23-epoxy-2alpha,3alpha,19alpha-trihydroxy-24-norurs-12-en-28-oic acid (2), along with the known compounds myrianthic acid (3), tormentic acid, and emodin. The structures of 1 and 2 were elucidated by spectroscopic methods, particularly by extensive 1D and 2D NMR studies.

Carbohydrate Conformation↗
PubMed2001

[Studies on chemical constituents in root of Rumex patientia L].

OBJECTIVE: Investigating the chemical constituents in the root of Rumex patientia. METHOD: Compounds were separated by rechromatography on silica gel. Their structures were determined by spectral analysis and chemical evidence. RESULT: Eight compounds were isolated and identified as 5-methoxy-7-hydroxy-1 (3H)-benzofuranone (I), 5, 7-dihydroxy-1 (3H)-benzofuranone(II), nonadecanoic acid-2,3-dihydroxypropyl ester(III), torachrysone-8-O-beta-D-glucopyranoside(IV), gallic acid(V), beta-sitosterol(VI), beta-sitosterol-3-O-beta-D-glucopyranoside(VII) and catechin(VIII). CONCLUSION: Compound III is a new natural products, and compounds I and II were obtained from this plant for the first time.

Benzofurans↗
PubMed2002

The effects of acarbose and Rumex patientia on liver ultrastructure in streptozotocin-induced diabetic (type II) rats.

The aim of this study was to investigate the effects of acarbose and Rumex patientia on liver ultrastructure in streptozotocin (STZ)-induced diabetic (type II) rats. Forty-two-day-old, neonatal Wistar albino rats were used. They were divided into six groups. STZ was injected into groups 4, 5 and 6 on postnatal day 2. Groups 1 and 5 received water, groups 2 and 6 received 2% decoction of R. patientia grain and groups 3 and 4 received 40 mg acarbose/100 g feed. During the experimental period, blood glucose levels were checked periodically and HbA1c levels were measured from cardiac blood at the end of the experiment. In addition, liver tissue was examined by electron microscopy. Our results showed that glucose and HbA1c levels, which are increased by STZ, were decreased by acarbose and R. patientia. In group 5, most of the mitochondria of hepatocytes were swollen and some hepatocytes contained lipid granules in their cytoplasm. In group 4, no pathological changes were observed in hepatocytes, but some lysosomes were found in their cytoplasms. In group 6, mitochondrial changes were minimal compared with those in group 5, and no lipid granules were observed in hepatocytes.

Acarbose↗
PubMed2003

Evaluation of neuropharmacological effects of Rumex maritimus Linn. (Polygonaceae) root extracts.

Hexane, ethyl acetate and methanol extracts of the root of Rumex maritimus Linn. (Polygonaceae) were evaluated for neuropharmacological activities in different models. All the extracts significantly and dose dependently inhibited acetic acid induced abdominal constrictions in mice. The hexane and methanol extract exhibited significant central analgesic activity in the radiant heat method. Only the methanol extract showed statistically significant mild to moderate central nervous system depressant activity assessed by hole cross, open field and hole board test in the mice model.

Acetic Acid↗
PubMed2004

Effects of Rumex patientia root extract on indomethacine and ethanol induced gastric damage in rats.

The effects of an aqueous root extract from Rumex patientia (D-1) compared to COX-2 selective inhibitors on indomethacine and ethanol induced stomach ulcers were investigated. Adult male Wistar albino rats, weighing between 185-200 g were used. It was determined that D-1 does not show its gastroprotective activity via a COX enzyme in indomethacine induced ulcers. Antioxidant effects protect the gastrointestinal system. The effect of D-1 in ethanol induced ulcers may also be due to its antioxidant effect.

Animals↗