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At least 19 recordsLinked to original sources
PubMed1992

Interactions of plant zinc and plant species on the bioavailability of plant cadmium to Japanese quail fed lettuce and spinach.

Many cadmium-contaminated environments contain high levels of zinc. The effects of plant Zn and plant species on plant Cd bioavailability were tested in Japanese quail fed lettuce and spinach. Four groups of birds received 10% of their diets as lettuce or spinach leaves intrinsically labeled with 109Cd and containing low or high intrinsic Zn. Two other groups were fed control diets containing 109Cd as CdSO4 and low or high Zn as ZnCO3. Cadmium concentrations in diets ranged from 0.857 to 1.05 micrograms/g dry wt. Zinc concentrations in low-Zn diets ranged from 21.2 to 22.8, and in high-Zn diets from 56.0 to 63.3 micrograms/g dry wt. Increased lettuce and spinach Zn decreased plant Cd retention in kidney, liver, and jejunum-ileum of Japanese quail. Spinach Cd was less absorbed than lettuce Cd at both Zn levels. Inorganic Zn produced a lesser decrease in Cd retention in kidney, liver, and jejunum-ileum than did plant Zn. We conclude that (1) crops that transport Zn and Cd readily into edible tissues show lower Cd bioavailability when grown in Zn-Cd contaminated environments than in Cd-only polluted sites, (2) plant species differ in Cd bioavailability for identical concentrations of Zn and Cd in edible tissues, and (3) toxicological studies with animals exposed to Cd salts and Zn supplements do not assess Cd bioavailability of Zn-Cd contaminated crops.

Absorption↗
PubMed1990

How plants respond to stimuli. The Ninth Annual Symposium on Current Topics in Plant Biochemistry and Physiology sponsored by the University of Missouri Interdisciplinary Program in Plant Biochemistry and Physiology, the US Department of Agriculture, and the National Science Foundation, Columbia, MO, USA, April 4-7, 1990.

With the rapid progress in the identification of the molecular components of calcium and protein kinase regulatory systems, it is presently an exciting time for those studying plant signal transduction. A clear message that was conveyed at the meeting was the need for an interdisciplinary approach to the problems currently facing researchers in this area. Thus, while the powerful methods of plant molecular biology allow for rapid advances in the identification of new molecules, this approach needs to be combined with careful biochemical and physiological analyses. This was exemplified by the large number of protein kinases described at the meeting but the surprisingly few reports of physiological function of phosphorylation. Similarly, while calcium has emerged as a major regulatory molecule in plants, little is known regarding the exact molecular mechanisms of calcium and calcium-modulatory protein action. These are clearly areas for future study that should reveal the elusive pathways that lie between stimuli and responses in the plant cell.

Calcium↗
PubMed1991

Phenotypically normal transgenic T-cyt tobacco plants as a model for the investigation of plant gene expression in response to phytohormonal stress.

The tumour-inducing T-DNA gene 4 (T-cyt gene) of the nopaline Ti plasmid pTiC58 was cloned and introduced into tobacco cells by leaf disc transformation using Agrobacterium plasmid vectors. Tobacco shoots exposed to elevated cytokinin levels were unable to develop roots and lacked apical dominance. Using exogenously applied phytohormone manipulations we were able to regenerate morphologically normal transgenic tobacco plants which differed in endogenous cytokinin levels from normal untransformed plants. Although T-cyt gene mRNA levels, as revealed by dot-blot hybridization data, in these rooting plants were only about half those in primary transformed shoots the total amount of cytokinins was much lower than in crown gall tissue or cytokinin-type transformed shoots as reported by others. Nevertheless the cytokinin content in T-cyt plants was about 3 times greater than in control tobacco plants. Elevated cytokinin levels have been shown to change the expression of several plant genes, including some nuclear genes encoding chloroplast proteins. Our results show that the mRNA levels of chloroplast rbcL gene increase in cytokinin-type transgenic tobacco plants as compared with untransformed plants. Data obtained suggest that T-cyt transgenic plants are a good model for studying plant gene activity in different parts of the plant under endogenous cytokinin stress.

Agrobacterium tumefaciens↗
PubMed1978

Soil and plant factors influencing the accumulation of heavy metals by plants.

The use of plants to monitor heavy metal pollution in the terrestrial environment must be based on a cognizance of the complicated, integrated effects of pollutant source and soil-plant variables. To be detectable in plants, pollutant sources must significantly increase the plant available metal concentration in soil. The major factor governing metal availability to plants in soils is the solubility of the metal associated with the solid phase, since in order for root uptake to occur, a soluble species must exist adjacent to the root membrane for some finite period. The rate of release and form of this soluble species will have a strong influence on the rate and extent of uptake and, perhaps, mobility and toxicity in the plant and consuming animals. The factors influencing solubility and form of available metal species in soil vary widely geographically and include the concentration and chemical form of the element entering soil, soil properties (endogenous metal concentration, mineralogy, particle size distribution), and soil processes (e.g., mineral weathering, microbial activity), as these influence the kinetics of sorption reactions, metal concentration in solution and the form of soluble and insoluble chemical species. The plant root represents the first barrier to the selective accumulation of ions present in soil solution. Uptake and kinetic data for nutrient ions and chemically related nonnutrient analogs suggest that metabolic processes associated with root absorption of nutrients regulate both the affinity and rate of absorption of specific nonnutrient ions. Detailed kinetic studies of Ni, Cd, and Tl uptake by intact plants demonstrate multiphasic root absorption processes over a broad concentration range, and the use of transport mechanisms in place for the nutrient ions Cu, Zn, and K. Advantages and limitations of higher plants as indicators of increased levels of metal pollution are discussed in terms of these soil and plant phenomena.

Absorption↗
PubMed1992

Monitoring and assessment of mercury pollution in the vicinity of a chloralkali plant. IV. Bioconcentration of mercury in in situ aquatic and terrestrial plants at Ganjam, India.

In situ aquatic and terrestrial plants including a few vegetable and crop plants growing in and around a chloralkali plant at Ganjam, India were analyzed for concentrations of root and shoot mercury. The aquatic plants found to bioconcentrate mercury to different degrees included Marsilea spp., Spirodela polyrhiza, Jussiea repens, Paspalum scrobiculatam, Pistia stratiotes, Eichhornia crassipes, Hygrophila schulli, Monochoria hastata and Bacopa monniera. Among wild terrestrial plants Chloris barbata, Cynodon dactylon, Cyperus rotundus and Croton bonplandianum were found growing on heavily contaminated soil containing mercury as high as 557 mg/kg. Analysis of mercury in root and shoot of these plants in relation to the mercury levels in soil indicated a significant correlation between soil and plant mercury with the exception of C. bonplandianum. Furthermore, the tolerance to mercury toxicity was highest with C. barbata followed by C. dactylon and C. rotundus, in that order. The rice plants analyzed from the surrounding agricultural fields did not show any significant levels of bioconcentrated mercury. Of the different vegetables grown in a contaminated kitchen garden with mercury level at 8.91 mg/kg, the two leafy vegetables, namely cabbage (Brassica oleracea) and amaranthus (Amaranthus oleraceous), were found to bioconcentrate mercury at statistically significant levels. The overall study indicates that the mercury pollution is very much localized to the specific sites in the vicinity of the chloralkali plant.

Environmental Monitoring↗
PubMed1992

Plant nurseries: a reliable resource for plant identification?

Poison Centers frequently rely on the assistance of local plant nurseries to identify unknown plants involved in exposures. The reliability and accuracy of utilizing this method has never been studied; therefore, our objective was to evaluate this primary resource of plant identification. A study was done in which callers were instructed to take plant samples to a local nursery for visual identification. Once the patient was treated according to our normal protocol, the plant specimen was sent to a botanist for a second identification. The botanist provided his identification results through a blinded process. The collected data was gathered from 68 cases that completed the necessary study criteria. In 58% of the cases, plant nurseries were an unreliable source for plant identification. These incorrect identifications resulted in the "undertreatment" in 24% of the exposures.

Animals↗
PubMed1990

Expression of a yeast-derived invertase in the cell wall of tobacco and Arabidopsis plants leads to accumulation of carbohydrate and inhibition of photosynthesis and strongly influences growth and phenotype of transgenic tobacco plants.

Chimeric genes consisting of the coding sequence of the yeast invertase gene suc 2 and different N-terminal portions of the potato-derived vacuolar protein proteinase inhibitor II fused to the 35S CaMV promoter and the poly-A site of the octopine synthase gene were transferred into tobacco and Arabidopsis thaliana plants using Agrobacterium based systems. Regenerated transgenic plants display a 50- to 500-fold higher invertase activity compared to non-transformed control plants. This invertase is N-glycosylated and efficiently secreted from the plant cell leading to its apoplastic location. Whereas expression of the invertase does not lead to drastic changes in transgenic Arabidopsis thaliana plants, transgenic tobacco plants show dramatic changes with respect to development and phenotype. Expression of the invertase leads to stunted growth due to reduction of internodal distances, to development of bleached and/or necrotic regions in older leaves and to suppressed root formation. In mature leaves, high levels of soluble sugars and starch accumulate. These carbohydrates do not show a diurnal turnover. The accumulation of carbohydrate is accompanied by an inhibition of photosynthesis, and in tobacco, by an increase in the rate of respiration. Measurements in bleached versus green areas of the same leaf show that the bleached section contains high levels of carbohydrates and has lower photosynthesis and higher respiration than green sections. It is concluded that expression of invertase in the cell wall interrupts export and leads to an accumulation of carbohydrates and inhibition of photosynthesis.

Amino Acid Sequence↗
PubMed1990

Study into wild Egyptian plants of potential medicinal activity. Ninth communication: hypoglycaemic activity of some selected plants in normal fasting and alloxanised rats.

31 desert plants belonging to 17 families were collected from different Egyptian localities. 21 plants extracts were orally given to normal rats, and 15 were tested on fasted and to alloxanised rats. The results were compared with a standard oral hypoglycaemic drug (Daonil, Hoechst) used as a positive control. The following findings were obtained: 8 plants exhibited persistent hypoglycaemic effects, Lycium shawii, Salvia (S.) aegyptiaca, Pergularia tomentosa, Convolvulus (C.) althaeoides, Haloxylon salicornicum, Ephedra alata, Scrophularia deserti, and Crotalaria aegyptiaca. Transient hypoglycaemic effects appeared only 1 hour after administration in response to 4 plants, Silena succulenta, Lygos raetam, C. lanatus, and Pulicaria incisa. In the cases of Ochradenus baccatus and Zygophyllum album, slow hypoglycaemic activity was produced and appeared 3 hours after administration. 5 plants showed hypoglycaemic effects viz, Thymus capitatus, Launaea nudicaulis, Conyza dioscorides, Nitraria retusa, and Limonium tubiflorum. Among the 15 plant extracts tested on alloxanised diabetic rats only 4 showed hypoglycaemic effects more potent than those of the administered dose of Daonil. These were Matthiola livida, S. aegyptiaca, Astragalus species, and Arthrocnemum glaucum. The hypoglycaemic effect of S. aegyptiaca in fasting rats has been confirmed also in alloxanised diabetic animals. This emphasises the importance of conducting both experiments in order to obtain a reliable conclusion.

Animals↗
PubMed1990

Construction of an intron-containing marker gene: splicing of the intron in transgenic plants and its use in monitoring early events in Agrobacterium-mediated plant transformation.

Agrobacterium tumefaciens is a commonly used tool for transforming dicotyledonous plants. The underlying mechanism of transformation however is not very well understood. One problem complicating the analysis of this mechanism is the fact that most indicator genes are already active in Agrobacterium, thereby preventing the precise determination of timing and localisation of T-DNA transfer to plant cells. In order to overcome this obstacle a modified prokaryotic indicator gene was constructed. The expression of this indicator gene and its use in analysing early events in Agrobacterium-mediated plant transformation are described. A portable intron, derived from a plant intron, was introduced into the beta-glucuronidase (GUS) gene. In transgenic plants containing this chimaeric gene the intron is spliced efficiently, giving rise to GUS enzymatic activity. Mapping of the splice junction indicates the exact removal of the intron. No GUS activity is detected in agrobacteria containing this construct due to the lack of a eukaryotic splicing apparatus in prokaryotes. Early phases after transformation of Arabidopsis cotyledon explants were analysed using this GUS-intron chimaeric gene showing that as early as 36 h after Agrobacterium infection significant GUS activity is detected. In vivo GUS staining of transformed cells clearly shows that quickly proliferating calli expressing GUS activity are formed, mainly at the cut surface. Minor transformation events occur however throughout the whole cotyledon. These data indicate that Agrobacterium-mediated T-DNA transfer to plants is much more efficient than has been judged from experiments where selection is applied immediately. The intron-containing GUS gene can be used as an optimised marker gene in transient and stable transformation experiments.

Base Sequence↗
PubMed1979

[Changes in DNA methylation in alfalfa plants infected with Cuscuta and tissue differences in DNA methylation of the parasite plants].

The tissue-specific differences in the 5-methylcytosine (m5C) content in total DNA of the parasite plant Cuscuta reflexa have been found: DNA from apical parts of the plant is less methylated (m5C = 4,2 mol %) as compared to the DNA from haustoria and posthaustorial regions (m5C = 5,4 mol %). The base compositions of total DNA preparations from C. reflexa grown on various hosts are similar. The m5C amount in stem DNA of the alfalfa plant infected with C. reflexa is by approximately 25% higher than that in the non-infected plant DNA. The GC content in alfalfa DNA does not change as a result of infection. Thus, the parasite induces the hypermethylation of DNA in the host plant. It is assumed that the changes in DNA methylation induced by the parasite plant may play a regulatory role and may cause changes in transcription and replication of host DNA.

Cytosine↗
PubMed1992

Plant endogenous beta-glucuronidase activity: how to avoid interference with the use of the E. coli beta-glucuronidase as a reporter gene in transgenic plants.

We have detected a plant beta-glucuronidase activity, present in several tissues and organs of plant species belonging to different families. The fluorimetric beta-glucuronidase assay was used to partially characterize this activity in post-ribosomal supernatants of tobacco leaves. The tobacco activity is very stable at low temperatures, but quickly inactivated above 45 degrees C. It is relatively resistant to proteases and insensitive to -SH group reagents and to ionic conditions. It does not require, nor is it inhibited by, divalent cations. Although these properties are shared by the Escherichia coli beta-glucuronidase, the two activities can be distinguished by: (i) their different sensitivity to the specific inhibitor saccharic acid-1,4-lactone; (ii) their different thermal stability (iii) their different pH optima (5.0 for the plant activity and close to neutral for the bacterial enzyme). Therefore, under appropriate experimental conditions, it should be possible to assay the E. coli beta-glucuronidase in transgenic plants without interference from the endogenous plant activity.

Escherichia coli↗
PubMed1977

Toxicants in plants and plant products.

Toxicants are widely distributed in plants and plant products, including intentionally added, incidentally added, and naturally occurring food toxicants. This review covers the toxicity of some food additives: the distribution, residues, toxicity, and methods of removal of some pesticides and toxic metals; and the presence of naturally occurring toxicants in plants and plant products. Extensive review has been done, particularly on natural toxicants. However, there are still extensive gaps in our knowledge pertaining to effect upon the health of many of the substances known to be present in natural plant food products, as well as even the identity of many natural chemical components of plant foods and their potential toxicological significance. An understanding of their presence, formation, and toxicity is important as far as public health is concerned.

Enzyme Inhibitors↗
PubMed1990

Plants used in Guatemala for the treatment of gastrointestinal disorders. 1. Screening of 84 plants against enterobacteria.

Gastrointestinal disorders are important causes of morbidity in developing countries. Natural healing is the traditional way of treating these diseases in Guatemala. Ethnobotanical surveys and literature reviews showed that 385 plants from 95 families are used in Guatemala for the treatment of gastrointestinal disorders. The activity of 84 of the most commonly used plants was screened in vitro against five enterobacteria pathogenic to man (enteropathogenic Escherichia coli, Salmonella enteritidis, Salmonella typhi, Shigella dysenteriae and Shigella flexneri). Results indicate that 34 (40.48%) plants inhibit one or more of the enterobacteria tested. The most commonly inhibited bacterium was S. typhi (33.73%) and the most resistant was E. coli (7.35%). The plants of American origin which exhibited the best antibacterial activity were: Byrsonima crassifolia, Diphysa robinioides, Gnaphalium stramineum, Guazuma ulmifolia, Psidium guajava, Sambucus mexicana, Simarouba glauca, Smilax lundelii, Spondias purpurea and Tagetes lucida. These results indicate a scientific basis for use of these medicinal plants for attacking enterobacterial infections in man.

Anti-Bacterial Agents↗
PubMed1991

Plants used in Guatemala for the treatment of dermatophytic infections. 1. Screening for antimycotic activity of 44 plant extracts.

Skin infections are common diseases in developing countries, of which dermatophytoses are of particular concern in the tropics, especially in infants. Through ethnobotanical surveys and literature review 100 plants were detected as being used in Guatemala for the treatment of dermatophytoses. Of these, 44 plants were screened for in vitro activity against the most common dermatophytes (Epidermophyton floccosum, Microsporum canis, Microsporum gypseum, Trichophyton mentagrophytes and Trichophyton rubrum). Results showed that aqueous extracts from 22 of the plants tested inhibit one or more of the dermatophytes. The most commonly inhibited dermatophytes were E. floccosum (43.2%), T. rubrum (36.0%), and T. mentagrophytes (31.8%); the less inhibited were M. canis (22.7%) and M. gypseum (24.0%). Plants of American origin which exhibited anti-dermatophyte activity were: Byrsonima crassifolia, Cassia grandis, Cassia occidentalis, Diphysa carthagenensis, Gliricidia sepium, Piscidia piscipula, Sambucus mexicana, Smilax regelii, Solanum americanum and Solanum nigrescens. Fungicidal and fungistatic activities as well as the minimal inhibitory concentration were demonstrated. These results provide a scientific basis for the use of these plants for the treatment of dermatophyte infections in man.

Antifungal Agents↗
PubMed2026

Phytoplasma-plant interactions: effector-mediated host reprogramming, hormonal crosstalk, metabolic alterations and plant-mediated vector manipulation.

Phytoplasmas are wall-less, phloem-restricted bacterial pathogens that infect over 1,000 plant species, causing substantial losses in agriculture, horticulture, and forestry worldwide. Despite their reduced genomes and limited metabolic autonomy, these obligate parasites colonize diverse hosts through secreted effector proteins that extensively reprogram plant development, metabolism, immune signalling, and vector interactions. Advances in genomics, transcriptomics, proteomics, metabolomics, and functional studies have substantially clarified the molecular basis of phytoplasma pathogenicity and symptom development. This review synthesizes current understanding of phytoplasma-plant interactions, covering phytoplasma biology, genome evolution, and the infection cycle across plant and insect vector hosts. We examine the molecular functions of key effectors, SAP11, SAP54/PHYL1, SAP05, TENGU, SWP1, and recently identified virulence factors, focusing on how they target host transcription factors, phytohormone networks, protein degradation pathways, and immune responses to promote colonization and disease progression. We further discuss how phytoplasma infection disrupts phytohormone signalling, primary and secondary metabolism, and developmental programs to produce characteristic disease symptoms, with particular attention to pathogen-induced changes in host volatiles and nutritional quality that alter vector behaviour and enhance transmission. Finally, we summarize insights from multi-omics studies and emerging management strategies, including CRISPR-based genome editing, RNAi, rapid molecular diagnostics, resistant cultivars, microbiome-based approaches, and sustainable vector control, and highlight key knowledge gaps and priorities for developing effective, environmentally sustainable phytoplasma disease management.

Phytoplasma↗
PubMed1991

Fluorescence emission spectra of plant leaves and plant constituents.

The UV-B radiation (e.g. 337 nm) induced blue fluorescence (BF) and red chlorophyll fluorescence spectra (RF) of green leaves from plants with different leaf structure were determined and the possible nature and candidates of the blue fluorescence emission investigated. The blue fluorescence BF is characterized by a main maximum in the 450 nm region and in most cases by a second maximum/shoulder in the 530 nm region. The latter has been termed green fluorescence GF. The red chlorophyll fluorescence RF, in turn, exhibits two maxima in the 690 and 730 nm region. In general, the intensity of BF, GF and RF emission is significantly higher in the lower than the upper leaf side. The ratio of BF to RF emission (F450/F690) seems to vary from plant species to plant species. BF and GF emission spectra appear to be a mixed signal composed of the fluorescence emission of several substances of the plant vacuole and cell wall, which may primarily arise in the epidermis. Leaves with removed epidermis and chlorophyll-free leaves, however, still exhibit a BF and GF emission. Candidates for the blue fluorescence emission (lambda max near 450 nm) are phenolic substances such as chlorogenic acid, caffeic acid, coumarins (aesculetin, scopoletin), stilbenes (t-stilbene, rhaponticin), the spectra of which are shown. GF emission (lambda max near 530 nm) seems to be caused by substances like the alkaloid berberine and quercetin. Riboflavine, NADPH and phyllohydroquinone K1 seem to contribute little to the BF and GF emission as compared to the other plant compounds. Purified natural beta-carotene does not exhibit any blue fluorescence.

Chloroplasts↗