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At least 469 records · Page 26Linked to original sources
PubMed2005

Suppression of damping-off disease in host plants by the rhizoplane bacterium Lysobacter sp. strain SB-K88 is linked to plant colonization and antibiosis against soilborne Peronosporomycetes.

We previously demonstrated that xanthobaccin A from the rhizoplane bacterium Lysobacter sp. strain SB-K88 suppresses damping-off disease caused by Pythium sp. in sugar beet. In this study we focused on modes of Lysobacter sp. strain SB-K88 root colonization and antibiosis of the bacterium against Aphanomyces cochlioides, a pathogen of damping-off disease. Scanning electron microscopic analysis of 2-week-old sugar beet seedlings from seeds previously inoculated with SB-K88 revealed dense colonization on the root surfaces and a characteristic perpendicular pattern of Lysobacter colonization possibly generated via development of polar, brush-like fimbriae. In colonized regions a semitransparent film apparently enveloping the root and microcolonies were observed on the root surface. This Lysobacter strain also efficiently colonized the roots of several plants, including spinach, tomato, Arabidopsis thaliana, and Amaranthus gangeticus. Plants grown from both sugar beet and spinach seeds that were previously treated with Lysobacter sp. strain SB-K88 displayed significant resistance to the damping-off disease triggered by A. cochlioides. Interestingly, zoospores of A. cochlioides became immotile within 1 min after exposure to a SB-K88 cell suspension, a cell-free supernatant of SB-K88, or pure xanthobaccin A (MIC, 0.01 microg/ml). In all cases, lysis followed within 30 min in the presence of the inhibiting factor(s). Our data indicate that Lysobacter sp. strain SB-K88 has a direct inhibitory effect on A. cochlioides, suppressing damping-off disease. Furthermore, this inhibitory effect of Lysobacter sp. strain SB-K88 is likely due to a combination of antibiosis and characteristic biofilm formation at the rhizoplane of the host plant.

Antibiosis↗
PubMed2005

Plant pigments (antioxidants) of medicinal plants Malva silvestris L. and Malva moschata L. (Malvaceae).

Qualitative-quantitative structure of plant pigments in wild plants Malva silvestrs L. and Malva moschata L. (Malvaceae), which were collected in 20 locations in Sarajevo area and surroundings, was tested during spring and summer in 2003. Acetone extracts of both categories were made and rising paper-chromatography done for the purpose of qualitative analysis. Quantitative analysis was done by spectrophotometry. Chlorophyll a, chlorophyll b and xanthophylls presence was confirmed by separation of pigments from acetone extract of these plant species. Spectrophotometric analysis of acetone extracts showed these results (given in mg/L): chlorophyll a 2,386, chlorophyll b 0,332 and carrotenoides 1,037. Data given in mg/g dry substance are: chlorophyll a 1,193x10(-2), chlorophyll b 1,66x10(-3), and carrotenoides 5,185x10(-3). Pigments structure (in mg/L) in species Malva moschata is 1,6 for chlorophyll; 1,419 for chlorophyll b; and 0,364 for carrotenoides. Data given in mg/g are: chlorophyll a 8x10(-3), chlorophyll b 7,09x10(-3), and carrotenoides 1,82x10(-3). Considering that species Malva moschata L. grows on ecologically clear soils as opposed to well-known medicinal species Malva sylvestris L., and considering the production of phytomass, phytochemical structure and pharmacological influence it can be considered very medical and be given advantage over this wider spread category.

Antioxidants↗
PubMed2003

Performance of Spodoptera litura Fabricius on different host plants: influence of nitrogen and total phenolics of plants and mid-gut esterase activity of the insect.

Five host plants [castor, Ricinus communis (Carolus Linnaeus); cotton, Gossypium hirsutm (Carolus Linnaeus); tomato, Lycopersicum esculentum (Philip Miller); mint, Mentha arvensis (Carolus Linnaeus) and cabbage, Brassica oleracea (Carolus Linnaeus)] belonging to different families were used to study the performance of the Asian armyworm, Spodoptera litura larvae. Highest consumption of food and dry weight gain was observed in larvae fed on castor. Mint did not support optimum larval growth because of low digestibility and low efficiency of conversion of digested food to body matter. Dry weight gain ranged from 26.64 mg on mint to 86.80 mg in castor. These differences tend to be related to nitrogen and total phenolics content of the leaf tissues; however, the most clear-cut correlation is an inverse one between the host plant preference and the ratio of total phenolics to nitrogen in the leaf tissues. Mid-gut esterase activity in larvae showed an increasing trend with the increase in total phenolics: nitrogen ratio in the test plants and the order of mid-gut esterase activity in larvae was mint > cabbage > cotton > tomato > castor.

Animals↗
PubMedDate not supplied

[Molecular-biological nature of morphological abnormalities induced by chronic irradiation in coniferous plants from the Chernobyl nuclear power plant exclusion zone: emphasis on a possible role of the cytoskeleton].

Results of the analysis of morphological abnormalities in coniferous plants from the Chernobyl exclusion zone are described. It is shown that such features as total and individual protein content, genome organization and peculiarities of its expression, and karyotype are different for the control and morphologically abnormal needles. A possible role of the cytoskeleton structures in the abnormal morphogenesis in plants is discussed.

Cytoskeleton↗
PubMed2005

Tobacco bZIP transcription factor TGA2.2 and related factor TGA2.1 have distinct roles in plant defense responses and plant development.

Salicylic acid (SA) is a crucial internal signaling molecule needed for the induction of plant defense responses upon attack of a variety of pathogens. Basic leucine zipper transcription factors of the TGA family bind to activating sequence-1 (as-1)-like elements which are SA-responsive cis elements found in promoters of 'immediate early' and 'late' SA-inducible genes. TGA2.2 constitutes the main component of tobacco as-1-binding factor-1 (ASF-1). TGA2.1, which differs from TGA2.2 by being able to activate transcription in yeast, constitutes a minor fraction of the complex. Both proteins interact with NPR1, a protein essential for SA inducibility of 'late' genes. Here we demonstrate using dsRNAi mediated gene silencing that reducing the amount of TGA2.2 and TGA2.1 correlates with a significant decrease in ASF-1 activity and with a decreased inducibility of both 'immediate early' and 'late' genes. In contrast, reducing the amount of TGA2.1 alone had no effect on the expression of these target genes suggesting that TGA2.1 is dispensable for SA-inducible gene expression from the as-1 element. Expression of a TGA2.2 mutant unable to form heterodimers with the endogenous pool of TGA factors led to reduced SA-inducibility of 'immediate early' gene Nt103, indicating that the native leucine zipper is important for the protein to act positively on transcription. Plants with reduced amounts of TGA2.1 developed petal like stamens indicating a regulatory role of TGA2.1 in defining organ identity in tobacco flowers. A model is suggested that unifies conflicting results on the function of tobacco TGA factors with respect to activation of the 'late' PR-1a promoter.

Cell Nucleus↗
PubMed1990

The plant G box promoter sequence activates transcription in Saccharomyces cerevisiae and is bound in vitro by a yeast activity similar to GBF, the plant G box binding factor.

G box and I box sequences of the Arabidopsis thaliana ribulose-bisphosphate-1,5-carboxylase small subunit (RBCS) promoter are required for expression mediated by the Arabidopsis rbcS-1A promoter in transgenic tobacco plants and are bound in vitro by factors from plant nuclear extracts termed GBF and GA-1, respectively. We show here that a -390 to -60 rbcS-1A promoter fragment containing the G box and two I boxes activates transcription from a truncated iso-1-cytochrome c (CYC1) gene promoter in Saccharomyces cerevisiae. Mutagenesis of either the rbcS-1A G box or both I box sequences eliminated the expression mediated by this fragment. When polymerized, I box oligonucleotides were also capable of enhancing expression from the truncated CYC1 promoter. Single-copy G box sequences from the Arabidopsis rbcS-1A, Arabidopsis Adh and tomato rbcS-3A promoters were more potent activators and were used in mobility shift assays to identify a DNA binding activity in yeast functionally similar to GBF. In methylation interference experiments, the binding specificity of the yeast protein was indistinguishable from that obtained with plant nuclear extracts.

Base Sequence↗
PubMed2005

Lipoxygenase inhibitors from natural plant sources. Part 1: Medicinal plants with inhibitory activity on arachidonate 5-lipoxygenase and 5-lipoxygenase[sol ]cyclooxygenase.

Arachidonate 5-lipoxygenase is the key enzyme in leukotriene biosynthesis and catalyses the initial steps in the conversion of arachidonic acid to biologically active leukotrienes. Leukotrienes are considered as potent mediators of inflammatory and allergic reactions and regarding their pro-inflammatory properties the inhibition of 5-lipoxygenase pathway is considered to be interesting in the treatment of a variety of inflammatory diseases. Besides 5-lipoxygenase inhibitors, drugs able to block the 5-lipoxygenase as well as the cyclooxygenase metabolic pathway are also of therapeutic value. A potential source for new 5-lipoxygenase inhibitors is undoubtedly provided by the abundance of medicinal plants used in traditional medicine. The present review article reports the results from a comprehensive literature search of plants that have been tested for 5-lipoxygenase inhibitory activity over the past 15 years. The obtained information is summarized in a tabular format and promising plant species and chemical classes of compounds are presented. Relevant in vitro tests are also described in this article.

Humans↗
PubMed1984

On the use of plants and plant-derived compounds for the control of schistosomiasis.

The rising costs of chemotherapy and synthetic molluscides have led to an increasing interest in plants which are lethal to the intermediate host of schistosomiasis (bilharzia). Over one thousand species have been tested but only a few have been phytochemically examined. Approximately fifty molluscicidal compounds have so far been isolated from plants, including saponins, terpenoids, flavonoids, naphthoquinones and tannins. The saponins from Phytolacca dodecandra are the most active and have been successfully employed in field tests. The latest results in this area and the problems involved in the use of plants and natural products for the control of schistosomiasis are discussed here.

Animals↗
PubMed1990

Plants contain multiple biotin enzymes: discovery of 3-methylcrotonyl-CoA carboxylase, propionyl-CoA carboxylase and pyruvate carboxylase in the plant kingdom.

Acetyl-CoA carboxylase is the sole biotin enzyme previously reported in plants. Western analysis with 125I-streptavidin of proteins extracted from carrot somatic embryos visualized six biotin-containing polypeptides, the relative molecular masses of which are 210,000, 140,000, 73,000, 50,000, 39,000, and 34,000. This multiplicity of the biotin-containing polypeptides can be partly explained by the discovery of 3-methylcrotonyl-CoA carboxylase, propionyl-CoA carboxylase, and pyruvate carboxylase in extracts of somatic carrot embryos, biotin enzymes previously unknown in the plant kingdom. These biotin enzymes seem to be widely distributed in the plant kingdom.

Animals↗
PubMed1992

Regioselectivity of a plant lauric acid omega hydroxylase. Omega hydroxylation of cis and trans unsaturated lauric acid analogs and epoxygenation of the terminal olefin by plant cytochrome P-450.

The study of the stereochemistry and regioselectivity of plant fatty acid hydroxylases is hampered by the difficulty to purify plant cytochrome P-450 enzymes. To provide an alternative, we have now defined an experimental plant system which expresses only one hydroxylase activity towards lauric acid: microsomes from clofibrate-induced Vicia sativa seedlings hydroxylate this fatty acid exclusively at the methyl terminus. To explore the catalytic capabilities of this laurate oxidase, a series of 1-14C-radiolabeled unsaturated lauric acid analogs (7-, 8-, 9-, 10- and 11-dodecenoic acids) were synthesized. Microsomes from clofibrate induced Vicia sativa seedling catalyzed the omega-oxidation of the lauric acid analogs in the presence of O2 and NADPH. The cis and trans forms of the four in-chain unsaturated analogs of lauric acid were 12-hydroxylated with similar efficiency. The terminal olefin was readily converted to the epoxide with only marginal autocatalytic inactivation of the enzyme. The formation of each metabolite was inhibited to the same extend when microsomes were incubated in presence of carbon monoxide or a suicide-substrate for omega LAH, suggesting that a single cytochrome P-450 isoenzyme from Vicia sativa microsomes is able to omega hydroxylate lauric acid and in-chain unsaturated analogs, and to epoxygenate 11-dodecenoic acid.

Alkenes↗
PubMed1988

Studies on the use of plant extracts in assessing the effects of plant metabolism on the mutagenicity and toxicity of pesticides.

We have carried out studies on the effects of plant metabolism on the mutagenicity of agricultural chemicals. Our approach is to use a cell-free plant extract, as a source of metabolic enzymes, in a standard Ames test. Using a number of test compounds, we observe that plant metabolism can alter the mutagenicity of several pesticides, and can in some instances give rise to metabolites apparently unique from those which are formed in animal cells. A number of parameters of the assay have been examined, and we find that the assay temperature and preincubation of the pesticide with the extract can significantly alter the outcome of the test. We also have devised a method of controlling for the effects that natural extracts can have on the spontaneous reversion rate of the Salmonella tester strains, in an effort to distinguish slight mutagenic responses from the effects of nutrients (e.g. histidine for his- bacteria) in the assay.

Animals↗
PubMed1990

Plant-derived sweetening agents: saccharide and polyol constituents of some sweet-tasting plants.

Samples of the sweet-tasting species Acanthospermum hispidum DC. (Compositae) (aerial parts), Boscia salicifolia Oliv. (Capparidaceae) (stem bark), Hovenia dulcis Thunb. (Rhamnaceae) (peduncles) and Inga spectabilis Willd. (Leguminosae) (arils) were acquired as part of a continuing search for high-intensity natural sweeteners of plant origin. Following their preliminary safety evaluation, the sweetness of these plants was traced to large amounts of sugars and polyols by taste-guided fractionation, which were identified and quantified using gas chromatography/mass spectrometry. The combined yields of sugars and polyols in the A. hispidum, B. salicifolia, H. dulcis, and I. spectabilis samples investigated were 6.9, 10.1, 18.4 and 12.1% w/w, respectively. These yields are much higher than the total saccharide and polyol content (2.4% w/w) of the sweet dried fruits of Thladiantha grosvenorii (Swingle) C. Jeffrey (Cucurbitaceae), a species which has previously been reported to contain more than 1% w/w of the intensely sweet triterpene, mogroside V. The dried leaves of Symplocos tinctoria (L.) L'Hérit. (Symplocaceae), which were not appreciably sweet, were found to contain only 2.0% w/w of sugars. The results of this investigation, therefore, suggest that unless the saccharide and/or polyol content of a plant part is well over 5% w/w, then it is unlikely to exhibit an overtly sweet taste, unless an intense sweetener is present.

Alcohols↗
PubMed1991

Ethnobotanical review of medicinal plants from Thai traditional books, Part II: Plants with antidiarrheal, laxative and carminative properties.

A survey of medicinal plants used in Thailand has been made from Thai books on traditional herbal medicine. In this part of the survey, 326 plants with antidiarrheal, laxative and/or carminative properties are described. Information provided for each species includes plant part used, methods of preparation and administration and literature references to Thai books, together with indications of usage in other Southeast Asian countries and of phytochemical work which has been performed.

Antidiarrheals↗
PubMed2004

The plant uncoupling protein homologues: a new family of energy-dissipating proteins in plant mitochondria.

Uncoupling proteins (UCPs) form a subfamily within the mitochondrial carrier protein family, which catalyze a free fatty acid-mediated proton recycling and can modulate the tightness of coupling between mitochondrial respiration and ATP synthesis. As in mammalian tissues, UCPs are rather ubiquitous in the plant kingdom and widespread in plant tissues in which they could have various physiological roles, such as heat production or protection against free oxygen radicals. The simultaneous occurrence in plant mitochondria of two putative energy-dissipating systems, namely UCP which dissipates the proton motive force, and alternative oxidase (AOX) which dissipates the redox potential, raises the question of their functional interactions.

Carrier Proteins↗
PubMed1997

Atomic force microscopy of plant cell walls, plant cell wall polysaccharides and gels.

Methods developed for the routine imaging of polysaccharides by atomic force microscopy (AFM) have been used to image plant polysaccharides from higher plants (pectin) and algae (carrageenan). These methods have been extended to image K-carrageenan association in hydrated films. Finally, AFM has been used to image polysaccharide architecture in moist plant cell walls. Simple experimental and image processing methods have been used to enhance molecular structure in 'rough' cell wall surfaces.

Cell Wall↗
PubMed2004

Plant-plant signaling: application of trans- or cis-methyl jasmonate equivalent to sagebrush releases does not elicit direct defenses in native tobacco.

Nicotiana attenuata plants growing in close proximity to damaged sagebrush (Artemisia tridentata ssp. tridentata) suffer less herbivory than plants near undamaged sagebrush. Sagebrush constitutively releases methyl jasmonate (MeJA), a compound that when applied directly to N. attenuata, elicits herbivore resistance and the direct defense traits [protease inhibitors (PIs), nicotine]. Damage increases the release of volatile MeJA, primarily in the cis epimer, suggesting that cis-MeJA may mediate this apparent interplant signaling. We characterized sagebrush's MeJA plume before and after damage in nature and in the laboratory, and compared the activity of trans- and cis-MeJA in inducing PIs, nicotine, and Manduca sexta resistance in N. attenuata. We used both lanolin applications and aqueous sprays that mimic natural exposures, and we determined the amount of volatilized MeJA required to elicit a nicotine response in open-grown plants. Wounding rapidly and transiently increased cis-MeJA emissions from damaged parts (but not systemically), and the released plume did not rapidly dissipate in nature. cis-MeJA was not consistently more active than trans-MeJA, and the order of exposure (trans- then cis-) did not influence activity. We conclude that volatile MeJA, either trans- or cis-, when applied at levels consistent with those released by sagebrush does not elicit direct defenses in N. attenuata.

Acetates↗
PubMed2006

Fish-oil esters of plant sterols improve the lipid profile of dyslipidemic subjects more than do fish-oil or sunflower oil esters of plant sterols.

BACKGROUND: Fish-oil fatty acid esters of plant sterols (FO-PS) were shown to have hypotriglyceridemic and hypocholesterolemic properties in animal models. OBJECTIVE: The objective of the study was to evaluate the hypolipidemic effects of FO-PS supplementation in healthy hypercholesterolemic persons fed an olive oil (OO)-based diet. DESIGN: Twenty-one moderately overweight, hyperlipidemic subjects participated in a semi-randomized, single-blind, 4-period crossover study including 4 experimental isoenergetic diets of 4 wk each and 4-wk intervening washout periods. Diets contained 30% of energy as fat, of which 70% was from extra-virgin OO, and differed only in the supplement oil: OO, fish oil, FO-PS, or sunflower oil esters of plant sterols (SU-PS). Both fish oil and FO-PS provided 5.4 g total eicosapentaenoic and docosahexaenoic acids/d. FO-PS, SU-PS, and OO provided the equivalent of 1.7, 1.7, and 0.02 g free plant sterols/d, respectively. RESULTS: Fish oil and FO-PS resulted in fasting and postprandial plasma triacylglycerol concentrations that were markedly lower than those observed with OO and SU-PS (P = 0.0001), but to a different extent. LDL cholesterol was significantly lower after supplementation with FO-PS and SU-PS than at the end of the control OO diet (P = 0.0031 and 0.0407, respectively). HDL cholesterol was not affected. FO-PS and SU-PS resulted in a lower ratio of total to HDL cholesterol and lower apolipoprotein (apo) B concentrations than did OO and fish oil. The ratio of apoB to apoA was significantly lower after SU-PS consumption than after consumption of OO (P = 0.0126) and fish oil (P = 0.0292). FO-PS and SU-PS resulted in similar ratios of apoB to apoA. HDL2 and the ratio of HDL2 to HDL3 were significantly higher at the end of the FO-PS treatment than at the end of the OO (P = 0.0006), fish oil (P = 0.0036), and SU-PS (P = 0.0016) treatments. CONCLUSION: Supplementation of an OO-based diet with FO-PS may reduce cardiovascular disease risk more than does supplementation with fish oil or SU-PS.

Adult↗