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At least 325 records · Page 18Linked to original sources
PubMed2003

Plant cytochromes P450: tools for pharmacology, plant protection and phytoremediation.

Cytochromes P450 catalyse extremely diverse and often complex regiospecific and/or stereospecific reactions in the biosynthesis or catabolism of plant bioactive molecules. Engineered P450 expression is needed for low-cost production of antineoplastic drugs such as taxol or indole alkaloids and offers the possibility to increase the content of nutraceuticals such as phytoestrogens and antioxidants in plants. Natural products may serve important functions in plant defence and metabolic engineering of P450s is a prime target to improve plant defence against insects and pathogens. Herbicides, pollutants and other xenobiotics are metabolised by some plant P450 enzymes. These P450s are tools to modify herbicide tolerance, as selectable markers and for bioremediation.

Antineoplastic Agents↗
PubMed2001

Pig manure vermicompost as a component of a horticultural bedding plant medium: effects on physicochemical properties and plant growth.

This experiment was designed to characterize the physical, chemical and microbial properties of a standard commercial horticultural, greenhouse container, bedding plant medium (Metro-Mix 360), that had been substituted with a range of increasing concentrations (0%, 5%, 10%, 25%, 50% and 100% by volume) of pig manure vermicompost and to relate these properties to plant growth responses. The growth trials used tomatoes (Lycopersicon esculentum Mill.), grown in the substituted media for 31 days under glasshouse conditions, with seedling growth recorded in 20 pots for each treatment. Half of the tomato seedlings (10 pots per treatment) were watered daily with liquid inorganic fertilizer while the other half received water only. The percentage total porosity, percentage air space, pH and ammonium concentrations of the container medium all decreased significantly, after substitution of Metro-Mix 360 with equivalent amounts of pig manure vermicompost; whereas bulk density, container capacity, electrical conductivity, overall microbial activity and nitrate concentrations, all increased with increasing substitutions of vermicompost. The growth of tomato seedlings in the potting mixtures containing 100% pig manure vermicompost was reduced, possibly as a result of high soluble salt concentrations in the vermicompost and poorer porosity and aeration. The growth of tomato seedlings was greatest after substitution of Metro-Mix 360 with between 25% and 50% pig manure vermicompost, with more growth occurring in combinations of pig manure vermicompost treated regularly with a liquid fertilizer solution than in those with no fertilizer applied. Some of the growth enhancement in these mixtures seemed to be related to the combined effects of improved porosity, aeration and water retention in the medium and the high nitrate content of the substrate, which produced an increased uptake of nitrogen by the plant tissues, resulting in increased plant growth. When the tomato seedlings were watered daily with liquid inorganic fertilizer, substitution of Metro-Mix 360 with a very small amount (5%) of pig manure vermicompost resulted in a significant increase in the growth of tomato seedlings. Such effects could not be attributed solely to the nutritional or physical properties of the pig manure vermicompost. Therefore, it seems likely that the pig manure vermicompost provided other biological inputs, such as plant growth regulators into the container medium, that still need to be identified fully.

Animals↗
PubMed2001

Trade-offs in performance on different plants may not restrict the host plant range of the phytophagous mite, Tetranychus urticae.

We examined sib-mated lines of the phytophagous mite, Tetranychus urticae Koch, for trade-offs in performance on different plants. We found no significant trade-offs among 10 potential host plants examined. Trade-offs in performance were not detected in most cases, even when the variations in general performance (mean performance on all potential host plants) among the sib-mated lines were statistically adjusted, denying the possibility that this may be due to the variations in general performance among the lines. No evidence for trade-offs was obtained in an artificial selection experiment; on all tested plants, a line adapted to one marginal host plant exhibited higher performance than the control line. However, the general performance seemed to be negatively correlated with other adaptive traits of the mite, such as competition ability of adult males for their mates and overcrowding response of adult females. Such correlations may contribute to the maintenance of genetic variation in the general performance of T. urticae.

Animals↗
PubMed2003

Mitochondrial phosphatidylserine decarboxylase from higher plants. Functional complementation in yeast, localization in plants, and overexpression in Arabidopsis.

Plants are known to synthesize ethanolamine (Etn) moieties by decarboxylation of free serine (Ser), but there is also some evidence for phosphatidyl-Ser (Ptd-Ser) decarboxylation. Database searches identified diverse plant cDNAs and an Arabidopsis gene encoding 50-kD proteins homologous to yeast (Saccharomyces cerevisiae) and mammalian mitochondrial Ptd-Ser decarboxylases (PSDs). Like the latter, the plant proteins have putative mitochondrial targeting and inner membrane sorting sequences and contain near the C terminus a Glycine-Serine-Threonine motif corresponding to the site of proteolysis and catalytic pyruvoyl residue formation. A truncated tomato (Lycopersicon esculentum) cDNA lacking the targeting sequence and a chimeric construct in which the targeting and sorting sequences were replaced by those from yeast PSD1 both complemented the Etn requirement of a yeast psd1 psd2 mutant, and PSD activity was detected in the mitochondria of the complemented cells. Immunoblot analysis of potato (Solanum tuberosum) mitochondria demonstrated that PSD is located in mitochondrial membranes, and mRNA analysis in Arabidopsis showed that the mitochondrial PSD gene is expressed at low levels throughout the plant. An Arabidopsis knockup mutant grew normally but had 6- to 13-fold more mitochondrial PSD mRNA and 9-fold more mitochondrial PSD activity. Total membrane PSD activity was, however, unchanged in the mutant, showing mitochondrial activity to be a minor part of the total. These results establish that plants can synthesize Etn moieties via a phospholipid pathway and have both mitochondrial and extramitochondrial PSDs. They also indicate that mitochondrial PSD is an important housekeeping enzyme whose expression is strongly regulated at the transcriptional level.

Amino Acid Sequence↗
PubMed2007

Anisohydric but isohydrodynamic: seasonally constant plant water potential gradient explained by a stomatal control mechanism incorporating variable plant hydraulic conductance.

Isohydric and anisohydric regulations of plant water status have been observed over several decades of field, glasshouse and laboratory studies, yet the functional significance and mechanism of both remain obscure. We studied the seasonal trends in plant water status and hydraulic properties in a natural stand of Eucalyptus gomphocephala through cycles of varying environmental moisture (rainfall, groundwater depth, evaporative demand) in order to test for isohydry and to provide physiological information for the mechanistic interpretation of seasonal trends in plant water status. Over a 16 month period of monitoring, spanning two summers, midday leaf water potential (psi(leaf)) correlated with predawn psi(leaf), which was correlated with water table depth below ground level, which in turn was correlated with total monthly rainfall. Eucalyptus gomphocephala was therefore not seasonally isohydric. Despite strong stomatal down-regulation of transpiration rate in response to increasing evaporative demand, this was insufficient to prevent midday psi(leaf) from falling to levels below -2 MPa in the driest month, well into the region likely to induce xylem air embolisms, based on xylem vulnerability curves obtained in the study. However, even though midday psi(leaf) varied by over 1.2 MPa across seasons, the hydrodynamic (transpiration-induced) water potential gradient from roots to shoots (delta psi(plant)), measured as the difference between predawn and midday psi(leaf), was relatively constant across seasons, averaging 0.67 MPa. This unusual pattern of hydraulic regulation, referred to here as isohydrodynamic, is explained by a hydromechanical stomatal control model where plant hydraulic conductance is dependent on transpiration rate.

Plants↗
PubMed1994

Small nuclear RNA genes transcribed by either RNA polymerase II or RNA polymerase III in monocot plants share three promoter elements and use a strategy to regulate gene expression different from that used by their dicot plant counterparts.

RNA polymerase (Pol) II- and RNA Pol III-transcribed small nuclear RNA (snRNA) genes of dicotyledonous plants contain two essential upstream promoter elements, the USE and TATA. The USE is a highly conserved plant snRNA gene-specific element, and its distance from the -30 TATA box, corresponding to approximately three and four helical DNA turns in Pol III and Pol II genes, respectively, is crucial for determining RNA Pol specificity of transcription. Sequences upstream of the USE play no role in snRNA gene transcription in dicot plants. Here we show that for expression of snRNA genes in maize, a monocotyledonous plant, the USE and TATA elements are essential, but not sufficient, for transcription. Efficient expression of both Pol II- and Pol III-specific snRNA genes in transfected maize protoplasts requires an additional element(s) positioned upstream of the USE. This element, named MSP (for monocot-specific promoter; consensus, RGCCCR), is present in one to three copies in monocot snRNA genes and is interchangeable between Pol II- and Pol III-specific genes. The efficiency of snRNA gene expression in maize protoplast is determined primarily by the strength of the MSP element(s); this contrasts with the situation in protoplasts of a dicot plant, Nicotiana plumbaginifolia, where promoter strength is a function of the quality of the USE element. Interestingly, the organization of monocot Pol III-specific snRNA gene promoters closely resembles those of equivalent vertebrate promoters. The data are discussed in the context of the coevolution of Pol II- and Pol III-specific snRNA gene promoters within many eukaryotic organisms.

Arabidopsis↗
PubMed1996

A whole-plant, open, gas-exchange system for measuring net photosynthesis of potted woody plants.

Chambers were constructed to measure gas exchange of entire potted grapevines (Vitis vinifera L.). The plant enclosures were constructed from Mylar film, which is nearly transparent to photosynthetically active radiation. Maintaining a slight, positive, internal pressure allowed the Mylar chambers to inflate like balloons and required no other means of support. The whole-plant, gas-exchange chamber design and construction were simple and inexpensive. They were assembled easily, equilibrated quickly, and did not require cooling. They allowed for the measurement of any plants in a relatively short period. This system would enable the researcher to make replicated comparisons of treatment influences on whole-plant CO2 assimilation throughout the growing season. While CO2 measurement was the focus of this project, it would be possible to measure whole-plant transpiration with this system.

Carbon Dioxide↗
PubMed2005

[Historical study on the introduction and cultivation of medicinal plants in the Edo-era. 1. A paper on the cultivation of 12 medicinal plant species.].

This article describes a two-page response written by a translator in 1721, in which a reply is given regarding an inquiry made on October 5 to a Chinese person related to the cultivation of 12 medicinal plant species imported to Japan from China. One page, dated October 7, describes the cultivation method for seven species and the other page, dated October 10, describes the cultivation method for the other five species. These plants were imported to Japan for the purpose of domestic propagation as important materials for Chinese medicine at the Jyuzengi Medicinal Plant Garden in Nagasaki, and some of them were apparently sent to Koishikawa Medicinal Plant Garden in Edo (Tokyo). This is a historical document concerning when and which plants were imported for cultivation.

Agriculture↗
PubMed1990

Agrobacterium in plant disease, biological disease control and plant genetic engineering.

Plant pathogenic strains of Agrobacterium cause crown gall and hairy-root diseases. The abnormal cell proliferation of diseased tissues results from elevated plant hormonal levels within them. These levels are consequent upon the transfer of DNA portions (T-DNA) from Agrobacterium plasmids to host nuclei where they are integrated and where genes for hormone synthesis, borne on the T-DNA, are expressed in transformed host cells. This process has been exploited in plant genetic engineering by producing Agrobacterium mutants with deleterious genes removed from T-DNA, and with selected beneficial genes inserted in their place. Such mutants are able to infect and transform plants so that the beneficial genes are transferred to, and expressed in, the host plants, endowing them with desirable characteristics, including insect and disease resistance and herbicide tolerance. Biological control of Agrobacterium disease has been achieved using non-pathogenic Agrobacterium strains which produce an antibiotic specifically inhibitory to Agrobacterium pathogens. Use of one of these biocontrol strains is the first instance of a genetically engineered micro-organism being released commercially.

DNA Mutational Analysis↗
PubMed1991

Selection of hybrid plants obtained by electrofusion of vacuolated x evacuolated plant protoplasts in hypo-osmolar solution.

Vacuolated and evacuolated tobacco mesophyll protoplasts were electrically fused in hypo-osmolar media by using an alternating field of modulated amplitude for alignment. The vacuolated fusion partner was isolated from Nicotiana tabaccum L. cv Xanthi and the evacuolated one from the streptomycin-resistant strain Nicotiana tabaccum L. cv Petit Havana SR1. The field and osmolarity conditions used ensured relatively high yields of heterologous fusion products despite the differences in density and size of the parental cells. After removal of the evacuolated, streptomycin-resistant fused and unfused protoplasts by flotation of vacuole-containing cells on iso-osmolar sucrose medium, the cybrids and hybrids were cultured in 25 microliters drops of agarose. During the first 5 weeks the non-fused Xanthi-protoplasts were used as a nurse culture. After addition of streptomycin to the growth media, cybrids and hybrids were successfully selected whereas fused and unfused vacuole-containing protoplasts died within 6 days. Only the streptomycin-resistant cybrids and hybrids developed into whole plants. On average a yield of 0.025% of streptomycin-resistant plants (referred to the total number of parental cells) was obtained. Polyacrylamide gel electrophoresis of leaf extracts of these plants showed that at least 50% of the streptomycin-resistant plants had a hybrid-esterase isoenzyme pattern. The protocol can be generalised by fusion of iodoacetamide-inactivated vacuolated protoplasts with meristematic (or evacuolized) protoplasts carrying no genetic marker. Use of evacolated protoplasts for electrofusion with vacuole-containing protoplasts therefore offers a way of overcoming the lack of suitable genetic markers for hybrid selection.

Electric Stimulation↗
PubMed2006

Tolerance of transgenic canola plants (Brassica napus) amended with plant growth-promoting bacteria to flooding stress at a metal-contaminated field site.

The growth of transgenic canola (Brassica napus) expressing a gene for the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase was compared to non-transformed canola exposed to flooding and elevated soil Ni concentration, in situ. In addition, the ability of the plant growth-promoting bacterium Pseudomonas putida UW4, which also expresses ACC deaminase, to facilitate the growth of non-transformed and transgenic canola under the above mentioned conditions was examined. Transgenic canola and/or canola treated with P. putida UW4 had greater shoot biomass compared to non-transformed canola under low flood-stress conditions. Under high flood-stress conditions, shoot biomass was reduced and Ni accumulation was increased in all instances relative to low flood-stress conditions. This is the first field study to document the increase in plant tolerance utilizing transgenic plants and plant growth-promoting bacteria exposed to multiple stressors.

Biomass↗
PubMed2006

Shedding light on plant competition: modelling the influence of plant morphology on light capture (and vice versa).

A plant's morphology is both strongly influenced by local light availability and, simultaneously, strongly influences this local light availability. This reciprocal relationship is complex, but lies at the heart of understanding plant growth and competition. Here, we develop a sub-individual-based simulation model, cast at the level of interacting plant components. The model explicitly simulates growth, development and competition for light at the level of leaves, branches, etc., located in 3D space. In this way, we are able to explore the manner in which the low-level processes governing plant growth and development give rise to individual-, cohort-, and community-level phenomena. In particular, we show that individual-level trade-offs between growing up and growing out arise naturally in the model, and robustly give rise to cohort-level phenomena such as self-thinning, and community processes such as the effect of ecological disturbance on the maintenance of biodiversity. We conclude with a note on our methodology and how to interpret the results of simulation models such as this one.

Algorithms↗
PubMed2005

Functional markers and a 'systemic strategy': convergency between plant breeding, plant nutrition and molecular biology.

Research perspectives towards sustainable plant production through plant breeding on abiotic stress tolerance require interdisciplinary competence. The present paper wants to strengthen awareness of important activities or current insights in plant breeding, plant nutrition and molecular biology to facilitate approximation of the disciplines and to direct efforts in molecular biology early in development towards application. As a consequence of recent discussion on appropriate approaches in systems biology towards crop improvement, a global 'systemic strategy' is presented to identify functional marker candidates for abiotic stress tolerance more efficiently.

Breeding↗
PubMed1998

Expression and assembly of a full-length monoclonal antibody in plants using a plant virus vector.

We have used a tobacco mosaic virus-based vector to express monoclonal antibody (mAb) CO17-1A, directed to a colon cancer antigen, in plants. Genes encoding heavy and light chains of this antibody were introduced independently into the tobacco mosaic virus vector. Upon co-infection of Nicotiana benthamiana plants with both recombinant virus constructs, genes for heavy and light chains were expressed and assembled into a full-length antibody. A functional plant-expressed antibody was detected by ELISA and immunoblot in extracts from systemically infected leaves. This is the first report on the use of a plant virus vector to express and assemble a full-size antibody.

Antibodies, Monoclonal↗
PubMed1997

The plant 2-Cys peroxiredoxin BAS1 is a nuclear-encoded chloroplast protein: its expressional regulation, phylogenetic origin, and implications for its specific physiological function in plants.

2-Cys peroxiredoxins constitute a family of enzymes which catalyze the transfer of electrons from sulfhydryl residues to peroxides and are ubiquitously distributed among all organisms. This paper characterizes the higher plant 2-Cys-peroxiredoxin BAS1. (i) Escherichia coli over-expressing BAS1 exhibit increased tolerance for alkyl hydroperoxides in vivo. This result substantiates the peroxiredoxin function of BAS1. (ii) BAS1 protein is associated with the soluble chloroplast fraction of mesophyll protoplasts. Import and processing of in vitro-transcribed and cell-free translated BAS1 protein into isolated chloroplasts provides conclusive evidence that the plant-specific N-terminal extension of bas1 encodes the chloroplast import signal which targets the pre-form of BAS1 to the chloroplast stroma where it is cleaved to its mature size. (iii) Genomic analysis reveals that the targeting signal is encoded by a separate exon in Arabidopsis thalina. (iv) The amino acid sequence of the BAS1 core protein of higher plants has a higher degree of similarity to open reading frames in the genome of the bluegreen algae Synechochystis PCC sp. 6803 and in the plastome of the red algae Porphyra purpurea than to any other nuclear-encoded 2-Cys peroxiredoxin. Therefore, it is tempting to speculate that the chloroplast import signal was added to an ancestor gene of endosymbiotic origin in the course of plant evolution. (v) The bas1 gene expression is regulated under the control of the cellular redox state which is in accordance with the anti-oxidant function of the enzyme. While oxidative stressors increased expression only slightly, antioxidants such as reduced thiols strongly suppressed the transcript level. The implications of these findings are discussed with respect to the possible physiological functions of BAS1.

Amino Acid Sequence↗
PubMed1990

Translatability of a plant-mRNA strongly influences its accumulation in transgenic plants.

Current knowledge of parameters affecting RNA stability is very restricted in plants. Here we investigated factors which might contribute to the stability of a particular plant messenger RNA. To this end, insertion and deletion mutants were made in two different exons and an intron of the transcribed region of a well characterised patatin gene (pgT5). Mutant genes were expressed under the control of a strong leaf-stem specific promoter (ST-LS1) and analysed in vivo in transgenic tobacco plants. Northern analysis revealed the importance of the translatability of the mature messenger RNA with respect to its accumulation in transgenic plants. Enlargement of the 3' non-translated region by several hundred base-pairs reduced the steady state mRNA level slightly; the introduction of a stop codon leading to premature termination of translation of the RNA led to a dramatic decrease of the steady state mRNA level.

Base Sequence↗
PubMed2004

Dof domain proteins: plant-specific transcription factors associated with diverse phenomena unique to plants.

Dof (DNA-binding with one finger) domain proteins are plant-specific transcription factors with a highly conserved DNA-binding domain, which presumably includes a single C(2)-C(2) zinc finger. During the past decade, numerous Dof domain proteins have been identified in both monocots and dicots including maize, barley, wheat, rice, tobacco, Arabidopsis, pumpkin, potato, and pea. Biochemical, molecular biological and molecular genetic analyses revealed that Dof domain proteins function as a transcriptional activator or a repressor involved in diverse plant-specific biological processes. Although more physiological roles of Dof domain proteins would be elucidated in future because of numerous Dof domain proteins in plants, it is already evident that the Dof domain proteins play critical roles as transcriptional regulators in plant growth and development. Here I summarize our current knowledge about Dof domain proteins.

Amino Acid Sequence↗
PubMed1986

Gene cluster of Pseudomonas syringae pv. "phaseolicola" controls pathogenicity of bean plants and hypersensitivity of nonhost plants.

Loss of the ability of Pseudomonas syringae pv. "phaseolicola" NPS3121 to elicit a hypersensitive response on tobacco and other nonhost plants was associated with loss of pathogenicity on the susceptible host bean. Eight independent, prototrophic transposon Tn5 insertion mutants which had lost the ability to elicit a hypersensitive response on tobacco plants were identified. Six of these mutants no longer produced disease lesions on primary leaves of the susceptible bean cultivar Red Kidney and failed to elicit a hypersensitive response on the resistant bean cultivar Red Mexican and on the nonhost plants tomato, cowpea, and soybean. The two remaining mutants had reduced pathogenicity on Red Kidney bean and elicited variable hypersensitive responses on the other plants tested. Southern blot analysis indicated that each mutant carried a single independent Tn5 insertion in one of three EcoRI fragments of about 17, 7, and 5 kilobases. Marker exchange mutagenesis further supported the conclusion that the pleiotropic mutant phenotype was not associated with multiple Tn5 insertions. A genomic library of the wild-type strain was constructed in the cosmid vector pLAFR3. A recombinant plasmid, designated pPL6, that carried P. syringae pv. "phaseolicola" genomic sequences was identified by colony hybridization. This plasmid restored the wild-type phenotype to all but one mutant, suggesting that genes affected by the insertions were clustered. Structural analysis of pPL6 and the wild-type genome indicated that the 17- and 5-kilobase EcoRI fragments were contiguous in the strain NPS3121 genome.

Cloning, Molecular↗