[Anthracene derivatives in various Rumex species (Rumex conglomeratus MURR., Rumex hymenosepalus TORREY, Rumex orientalis)].
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The crude extracts of the leaves of Dodonaea viscosa and Rumex nervosus as well as of the root of Rumex abyssinicus were tested for anti-microbial and anti-inflammatory activities. It was observed that the three plants possess antibacterial activity against Streptococcus pyogenes and Staphylococcus aureus and strong activity against Coxsackie virus B3 and influenza A virus. In contrast, none of them exhibited anti-fungal activity. The anti-inflammatory activity test results verified that only R. abyssinicus inhibited the synthesis of prostaglandin (PG) E(2).
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Rumex acetosa is characterized by a multiple chromosome system (2n = 12 + XX for females, and 2n = 12 + XY1Y2 for males), in which sex is determined by the ratio between the number of X chromosomes and autosome sets. For a better understanding of the molecular structure and evolution of plant sex chromosomes, we have generated a sex chromosome specific library of R. acetosa by microdissection. The screening of this library has allowed us to identify 5 repetitive DNA families that have been characterized in detail. One of these families, DOP-20, has shown no homology with other sequences in databases. Nevertheless, the putative proteins encoded by the other 4 families, DOP-8, DOP-47, DOP-60, and DOP-61, show homology with proteins from different plant retroelements, including poly proteins from Ty3-gypsy- and Ty1-copia-like long terminal repeat (LTR) retroelements, and reverse transcriptase from non-LTR retro elements. Results indicate that sequences from these 5 families are dispersed throughout the genome of both males and females, but no appreciable accumulation or differentiation of these types of sequences have been found in the Y chromosomes. These repetitive DNA sequences are more conserved in the genome of other dioecious species such as Rumex papillaris, Rumex intermedius, Rumex thyrsoides, Rumex hastatulus, and Rumex suffruticosus, than in the polygamous, gynodioecious, or hermaphrodite species Rumex induratus, Rumex lunaria, Rumex con glom er atus, Rumex crispus, and Rumex bucephalo phorus, which supports a single origin of dioecious species in this genus. The implication of these transposable elements in the origin and evolution of the heteromorphic sex chromosomes of R. acetosa is discussed.
In this paper, we analyze a satellite-DNA family, the RAYSI family, which is specific of the Y chromosomes of Rumex acetosa, a dioecious plant species with a multiple sex-chromosome system in which the females are XX and the males are XY(1)Y(2). Here, we demonstrate that this satellite DNA is common to other relatives of R. acetosa, including Rumex papillaris, Rumex intermedius, Rumex thyrsoides and Rumex tuberosus that are also dioecious species with a multiple system of sex chromosomes. This satellite-DNA family is absent from the genomes of other dioecious Rumex species having an XX/XY sex-chromosome system. Our data confirm recent molecular phylogenies that support a unique origin for all dioecious species of Rumex and two separate lineages for species with single or complex sex-chromosome systems. Our data also support an accelerated degeneration of Y-chromosome in XX/XY(1)Y(2) species by the accumulation of satellite-DNA sequences. On the other hand, the particular non-recombining nature of the Y chromosomes of R. acetosa and their closest relatives lead to a particular mode of evolution of RAYSI sequences. Thus, mechanisms leading to the suppression of recombination between the Y chromosomes reduced the rate of concerted evolution and gave rise to the apparition of different RAYSI subfamilies. Thus, R. acetosa and R. intermedius have two subfamilies (the RAYSI-S and RAYSI-J subfamilies and the INT-A and INT-B subfamilies, respectively), while R. papillaris only has one, the RAYSI-J subfamily. The RAYSI-S and RAYSI-J subfamilies of R. acetosa differ in 83 fixed diagnostic sites and several diagnostic deletions while the INT-A and the INT-B of R. intermedius differ in 27 fixed diagnostic sites. Pairwise comparisons between RAYSI-S and RAYSI-J sequences or between INT-A and INT-B sequences revealed these sites to be shared mutations detectable in repeats of the same variant in same positions. Evolutionary comparisons suggest that the subfamily RAYSI-J has appeared in the common ancestor of R. acetosa and R. papillaris, in which RAYSI-J has replaced totally (R. papillaris) or almost totally the ancestral sequence (R. acetosa). This scenario assumes that RAYSI-S sequences should be considered ancestral sequences and that a secondary event of subfamily subdivision should be occurring in R. intermedius, with their RAYSI subfamilies more closely related to one another than with other RAYSI sequences. Our analysis suggests that the different subfamilies diverged by a gradual and cohesive way probably mediated by sister-chromatid interchanges while their expansion or contraction in number might be explained by alternating cycles of sudden mechanisms of amplification or elimination.
The genus Rumex includes hermaphroditic, polygamous, gynodioecious, monoecious, and dioecious species, with the dioecious species being represented by different sex-determining mechanisms and sex-chromosome systems. Therefore, this genus represents an exceptional case study to test several hypotheses concerning the evolution of both mating systems and the genetic control of sex determination in plants. Here, we compare nuclear intergenic transcribed spacers and chloroplast intergenic sequences of 31 species of Rumex. Our phylogenetic analysis supports a systematic classification of the genus, which differs from that currently accepted. In contrast to the current view, this new phylogeny suggests a common origin for all Eurasian and American dioecious species of Rumex, with gynodioecy as an intermediate state on the way to dioecy. Our results support the contention that sex determination based on the balance between the number of X chromosomes and the number of autosomes (X/A balance) has evolved secondarily from male-determining Y mechanisms and that multiple sex-chromosome systems, XX/XY1Y2, were derived twice from an XX/XY system. The resulting phylogeny is consistent with a classification of Rumex species according to their basic chromosome number, implying that the evolution of Rumex species might have followed a process of chromosomal reduction from x = 10 toward x = 7 through intermediate stages (x = 9 and x = 8).
Petiole growth of Rumex acetosa L., Rumex crispus L., and Rumex palustris Sm. in response to soil waterlogging was studied in relation to production of the gaseous plant hormone ethylene. Ethylene production was monitored in a flow-through system and a recently developed laser driven photoacoustic detection system, which allowed ethylene measurements as low as 6 picoliters per liter. R. acetosa showed a two-fold increase in ethylene production correlated with a slight enhancement of the growth of the petiole that developed during the waterlogging treatment. Both R. crispus and R. palustris showed a strong petiole elongation of existing as well as newly formed petioles, which was correlated with a 20-fold increase in ethylene production after approximately 7 days. Increased rates of ethylene production in R. palustris were related to a strong increase in 1-aminocyclopropane-1-carboxylic acid (ACC) concentration and a slight, but detectable, increase in ethylene forming enzyme activity. In R. acetosa on the other hand, only a very small increase in ACC concentration was observed. Changes in ethylene production in Rumex are strongly correlated with variation in ACC content and ethylene forming enzyme activity. The interaction between ethylene production/internal concentration and ethylene sensitivity of the three Rumex species is discussed in relation to their field location in a flooding gradient and their differential resistance toward waterlogging and submergence.
This study was performed to observe the effects of acarbose and Rumex patientia on morphological change of pancreatic B cells in streptozotocin (STZ)-induced diabetic (type 2) rats. Two-day-old Wistar albino rats were intraperitoneally injected with 100mg/kg of STZ or vehicle alone for control. Vehicle and STZ given rats were divided into six groups (1st, 2nd and the 3rd groups are control; the 4th, 5th and 6th groups are STZ groups). The 1st and the 4th groups received water, the 2nd and the 5th groups received 40 mg acarbose/100 g feed, the 3rd and the 6th groups received 2% decoction of Rumex patientia grain. During experimentation period, blood glucose levels were checked periodically, and HbA1c level was measured from cardiac blood at the end of the experiment. Pancreas tissues were examined by electron microscope. Glucose and HbA1c levels increased by STZ were decreased by acarbose and Rumex patientia. Morphologically, we found a mitochondrial vacuolization and swelling as well as dilatation of the endoplasmic reticulum in the B cells of STZ-induced diabetic rats. Also, a decrease in the secretory granules of B cells was observed in the STZ-induced diabetic group. No pathological changes were observed in the STZ+acarbose group. In the STZ+Rumex patientia group, a weak swelling in the B cells was observed in the some of the mitochondria.
The kinetics of chlorophyll and protein decomposition and the effect of gibberellic acid (GA) were examined in senescing leaf discs of Rumex crispus and R. obtusifolius. Loss of Rumex total chlorophyll proceeds at a slow rate for about 2 days followed by a period of rapid logarithmic decline. Chlorophyll b is lost at a slightly faster rate than chlorophyll a during senescence in discs as well as in situ. GA causes a complete cessation of net chlorophyll and protein degradation for several days in Rumex, in contrast to the incomplete senescence inhibition generally observed with cytokinins. GA is fully effective even when added at the middle of the logarithmic phase of chlorophyll loss. Senescence inhibition by GA is apparently gradually reversed upon GA removal. The cytokinins, kinetin and 6-benzylaminopurine, were also effective in Rumex leaf discs, indicating that the senescence retarding effect was not restricted to the gibberellins.
We developed SCAR primers based on isolated and sequenced male-specific fragments as identified in an AFLP analysis of the dioecious plant Rumex nivalis. PCR amplification using these primers on females and males resulted in fragments exclusively present in males. Co-amplification of the nuclear rDNA internal transcribed spacer 2 together with the male-specific fragment was applied as an internal control for successful PCR reactions to avoid false-negative sex scoring. With a length of about 164 bp, the AFLP fragment was of a similar size as the tandemly arranged, repetitive sequences of 180 bp located on the Y chromosomes of Rumex acetosa. The genetic distances between the Y-chromosomal sequences of R. nivalis and R. acetosa, both members of the section Acetosa, were substantial. We found intra-individual divergence among cloned sequences of the male-specific fragment in R. nivalis. The patterns of interspecific and intra-individual sequence variation found are in accordance with proposed modes of the evolution of sex chromosomes. Y chromosomes possibly arose only once in the genus Rumex and consist mainly of heterochromatic DNA. Due to the almost complete absence of selection on them, Y chromosomes are likely to accumulate large numbers of mutations.
Complete submergence of flooding-tolerant Rumex palustris plants strongly stimulates petiole elongation. This escape response is initiated by the accumulation of ethylene inside the submerged tissue. In contrast, petioles of flooding-intolerant Rumex acetosa do not increase their elongation rate under water even though ethylene also accumulates when they are submerged. Abscisic acid (ABA) was found to be a negative regulator of enhanced petiole growth in both species. In R. palustris, accumulated ethylene stimulated elongation by inhibiting biosynthesis of ABA via a reduction of RpNCED expression and enhancing degradation of ABA to phaseic acid. Externally applied ABA inhibited petiole elongation and prevented the upregulation of gibberellin A(1) normally found in submerged R. palustris. In R. acetosa submergence did not stimulate petiole elongation nor did it depress levels of ABA. However, if ABA concentrations in R. acetosa were first artificially reduced, submergence (but not ethylene) was then able to enhance petiole elongation strongly. This result suggests that in Rumex a decrease in ABA is a prerequisite for ethylene and other stimuli to promote elongation.
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.
Ethylene-enhanced leaf elongation upon submergence is part of the survival mechanism of Rumex palustris Sm. plants that grow in frequently flooded areas. Other Rumex species, like R. acetosa L., do not possess this ability and can therefore only survive in habitats that are not frequently inundated. Expansins are proteins that induce extension of isolated cell walls, and therefore might play a role in the stimulation of petiole elongation, also in Rumex. We report here on the identification of several gene sequences encoding for alpha-expansins in R. palustris and R. acetosa plants. The pattern of transcript accumulation of one of these genes, Rp-EXP1, could be correlated with the pattern of leaf elongation in R. palustris after submergence or ethylene treatment. Induction of expansin gene activity was not found in R. acetosa upon these treatments, indicating that ethylene induces the expression of expansin genes in leaves of species that exhibit flooding-induced shoot elongation.
A model is presented of the regulation of ethylene biosynthesis in relation to submergence and flooding resistance. It is based on time-course measurements of ethylene production, ethylene accumulation, and concentrations of free and conjugated 1-aminocyclo-propane-1-carboxylic acid (ACC) in submerged and drained flooding-resistant Rumex palustris Sm. and flooding-sensitive Rumex acetosella L. plants. From these data, in vivo reaction rates of the final steps in the ethylene biosynthetic pathway were calculated. According to our model, submergence stimulates ACC formation and inhibits conversion of ACC to ethylene in both Rumex species, and as a result, ACC accumulates. This may explain the stimulated ACC conjugation observed in submerged plants. Although submergence inhibited ethylene production, physical entrapment increased endogenous ethylene concentrations in both flooding-resistant R. palustris and flooding-sensitive R. acetosella plants. However, R. palustris plants controlled their internal ethylene levels in the long term by a negative regulation of ACC synthase induced by ethylene. In flooding-sensitive R. acetosella plants, absence of negative regulation increased internal ethylene levels to more than 20 [mu]L L-1 after 6 d of submergence. This may accelerate the process of senescence and contribute to their low level of flooding resistance.
The phenolic compounds of Rumex induratus leaves were determined by HPLC-DAD-MS/MS-ESI. The results revealed a profile composed of 19 compounds: caffeoyl-hexoside, two p-coumaroyl-hexoside isomers, feruloyl-hexoside, sinapoyl-hexoside, 6-C-hexosyl-quercetin, 8-C-hexosyl-luteolin, 6-C-hexosyl-luteolin, 6-C-hexosyl-apigenin, 3-O-hexosyl-quercetin, 3-O-rutinosyl-quercetin, 7-O-hexosyl-diosmetin, 3-O-rutinosyl-isorhamnetin, 7-O-(acetyl)-pento-hexosyl-diosmetin, 6-C-hexosyl-genkwanin, and four unidentified O-glycosyl-C-glycosylflavones. The quantification of the identified phenolics by HPLC-DAD showed 6-C-hexosyl-luteolin as the main compound. Organic acid composition was determined by HPLC-UV, revealing a high content of oxalic acid. R. induratus was also investigated for its capacity to act as a scavenger of DPPH and superoxide radicals. Good antioxidative results were obtained against both radicals. Unlike other species of the genus Rumex, R. induratus did not present any anthraquinone derivative.
Rumex palustris responds to total submergence by increasing the elongation rate of young petioles. This favours survival by shortening the duration of submergence. Underwater elongation is stimulated by ethylene entrapped within the plant by surrounding water. However, abnormally fast extension rates were found to be maintained even when leaf tips emerged above the floodwater. This fast post-submergence growth was linked to a promotion of ethylene production that is presumed to compensate for losses brought about by ventilation. Three sources of ACC contributed to post-submergence ethylene production in R. palustris: (i) ACC that had accumulated in the roots during submergence and was transported in xylem sap to the shoot when stomata re-opened and transpiration resumed, (ii) ACC that had accumulated in the shoot during the preceding period of submergence and (iii) ACC produced de novo in the shoot following de-submergence. This new production of ethylene was associated with increased expression of an ACC synthase gene (RP-ACS1) and an ACC oxidase gene (RP-ACO1), increased ACC synthase activity and a doubling of ACC oxidase activity, measured in vitro. Out of seven species of Rumex examined, a de-submergence upsurge in ethylene production was seen only in shoots of those that had the ability to elongate fast when submerged.
A study was conducted, using chlorophyll fluorescence, rapid fluorescence induction kinetics, and polyphasic fluorescence transients, to determine the effect of salt treatment and heat stress on PSII photochemistry in Rumex leaves. Salt treatment was accomplished by adding NaCl solutions of different concentrations ranging from 50 to 200 mmol/L. Heat stress was induced by exposing the plant leaves to temperatures ranging from 29 to 47 degrees C. The control plants were grown without NaCl treatment. The data acquired in this study showed that NaCl treatment alone had no effect on the maximal photochemistry of PSH or the polyphasic rise of chlorophyll fluorescence. However, the NaCl treatment modified heat stress on PSII photochemistry in Rumex leaves, which was manifested by a lesser heat-induced decrease in photochemical quenching (qP), efficiency of excitation energy capture by open PSII reaction centers (Fv'/Fm'), and quantum yield of PSII electron transport (phiPSII). The data also showed that NaCl treatment compromised the impact of heat stress on the capacity of transferring electrons from Q(A)- to Q(B). Furthermore, the NaCl treatment promoted heat resistance of O2-evolving complex (OEC). In summary, NaCl treatment enhanced the thermostability of PSII.
By measuring chlorophyll fluorescence, the effects of NaCl treatment on the maximal efficiency and heat tolerance of PSII were examined in leaves of Rumex seedlings. NaCl 200 mmol/L treatment had no effect on the maximal efficiency of PSII, but increased the heat tolerance of PSII in Rumex leaves. Compared with control leaves, the heat stress-induced decrease in F(v)/F(m) and the increase in F(k)/F(j) ratio were less in NaCl-treated leaves. In addition, the heat stress-induced decrease in photochemical quenching (q(P)), the efficiency of excitation energy capture by open PSII reaction center (F(v)' /F(m)') and the quantum yield of electron transport (PhiPSII) were less in NaCl-treated leaves. Moreover, the increase in the Q(B)-non-reducing PSII reaction center content was less in NaCl-treated leaves than in control leaves. Discussion was made on the possible mechanisms of the increase in the heat tolerance of PSII in NaCl-treated leaves.