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Results for “Plant engineering”

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At least 361 records · Page 20Linked to original sources
PubMed2001

The use of transgenic plants in the bioremediation of soils contaminated with trace elements.

The use of plants to clean-up soils contaminated with trace elements could provide a cheap and sustainable technology for bioremediation. Field trials suggested that the rate of contaminant removal using conventional plants and growth conditions is insufficient. The introduction of novel traits into high biomass plants in a transgenic approach is a promising strategy for the development of effective phytoremediation technologies. This has been exemplified by generating plants able to convert organic and ionic forms of mercury into the less toxic, volatile, elemental mercury, a trait that occurs naturally only in some bacteria and not at all in plants. The engineering of a phytoremediator plant requires the optimization of a number of processes, including trace element mobilization in the soil, uptake into the root, detoxification and allocation within the plant. A number of transgenic plants have been generated in an attempt to modify the tolerance, uptake or homeostasis of trace elements. The phenotypes of these plants provide important insights for the improvement of engineering strategies. A better understanding, both of micronutrient acquisition and homeostasis, and of the genetic, biochemical and physiological basis of metal hyperaccumulation in plants, will be of key importance for the success of phytoremediation.

Biodegradation, Environmental↗
PubMed2003

Plant biotechnology and breeding: allied for years to come.

Plant metabolic engineering is lagging behind other kinds of genetic manipulation of plants. Creating metabolic pathways or improving their yields requires a better understanding of plant metabolism and of its regulation. Metabolic Control Analysis provides an interpretation of experimental failures and a guide for manipulators. It suggests also that there might be intrinsic limits to raising yields in already abundant products. At present, these limits can be dealt with more effectively by plant breeding.

Biotechnology↗
PubMed2003

Engineering fructan metabolism in plants.

Fructans, or polyfructosylsucroses, are storage carbohydrates present in many higher plants. They are also considered healthy food ingredients. Engineering crops into high level production of specific fructan molecules is one of the mayor strategic research goals. Understanding the properties of fructosyltransferases is important, in order to direct the synthesis of fructans. In plants at least two fructosyltransferases are needed to synthesise fructans. One enzyme synthesises the fructan trisaccharide 1-kestose, the next enzyme uses 1-kestose for elongation and/or modification, producing longer fructans. The specificity of fructosyltransferases determines the type of glycosidic bond formed and the donor and acceptor substrates used. This enables the synthesis of many structurally diverse fructans. The production of these molecules in crops such as sugar beet and potato makes the commercial use of fructans feasible.

Biotechnology↗
PubMed1993

Use of organic solvents and potential worker exposure in the motor vehicle manufacturing industry.

This survey was designed to assist with planning epidemiologic studies of the effects of solvent exposure among motor vehicle manufacturing workers. The objectives were to identify subgroups of workers with solvent exposure, and to evaluate the availability of data for a job-exposure matrix (JEM). Of 65 plants selected, 31 (48%) participated. Participant plants represent all production activities initially included in the survey, and employ 97,655 hourly workers. About 14% of these workers use organic solvents (direct exposure), and 19% work in the proximity of solvent-using operations (indirect exposure). However, only 3% have direct exposure, and 6% have indirect exposure to large-volume (> or = 100 gallons/month)/high-frequency (hourly)-use solvents. The highest solvent exposure prevalence occurs in plants manufacturing engines and power train components and in metal degreasing/cleaning and painting tasks, and entails exposure to petroleum fractions, aromatic hydrocarbons, alcohols, and ketones. A JEM can be developed using plant records on job titles, work histories, production scheduling, and plant engineering, and using the corporate computerized personnel and industrial hygiene databases. However, information on solvent use and on exposure is adequate only for recent time periods.

Automobiles↗
PubMed2006

Engineering drought tolerance in plants: discovering and tailoring genes to unlock the future.

The ability of plants to tolerate drought conditions is crucial for agricultural production worldwide. Recent progress has been made in our understanding of gene expression, transcriptional regulation and signal transduction in plant responses to drought. Molecular and genomic analyses have facilitated gene discovery and enabled genetic engineering using several functional or regulatory genes to activate specific or broad pathways related to drought tolerance in plants. Several lines of evidence have indicated that molecular tailoring of genes has the potential to overcome a number of limitations in creating drought-tolerant transgenic plants. Recent studies have increased our understanding of the regulatory networks controlling the drought stress response and have led to practical approaches for engineering drought tolerance in plants.

Biotechnology↗
PubMed2002

A novel, two-component system for cell lethality and its use in engineering nuclear male-sterility in plants.

Ablation of cells by the controlled expression of a lethal gene can be used to engineer plant traits such as male sterility and disease resistance. However, it may not be possible to achieve sufficient specificity of expression to prevent secondary effects in non-targeted tissues. In this paper we demonstrate that the extracellular ribonuclease, barnase, can be engineered into two complementary fragments, allowing overlapping promoter specificity to be used to enhance targeting specificity. Using a transient system, we first show that barnase can be split into two inactive peptide fragments, that when co-expressed can complement each other to reconstitute barnase activity. When a luciferase reporter gene was introduced into plant cells along with genes encoding both partial barnase peptides, a substantial reduction in luciferase activity was seen. Cytotoxicity of the reconstituted barnase was demonstrated by crossing together parents constitutively expressing each of the barnase fragments, then assaying their progeny for the presence of both partial barnase genes. None of over 300 tomato seeds planted resulted in a viable progeny that inherited both transgenes. When expression of the partial barnase genes was instead targeted to the tapetum, male sterility resulted. All 13 tomato progeny that inherited both transgenes were male sterile, whereas the three progeny inheriting only the N-terminal barnase gene were male fertile. Finally, we describe how male sterility generated by this type of two-component system can be used in hybrid seed production.

Bacterial Proteins↗
PubMed2006

Engineering novel traits in plants through RNA interference.

RNA interference (RNAi) is a homology-dependent gene silencing technology that involves double-stranded RNA directed against a target gene or its promoter region. Using hairpin constructs, double-stranded RNA can be expressed in plants relatively easily, enabling this technology to be applied to a wide range of species to silence the expression of both specific endogenous genes and genes of invading pathogens. RNAi has also been used to engineer metabolic pathways to overproduce secondary products with health, yield or environmental benefits. The application of tissue-specific or inducible gene silencing, with the use of appropriate promoters, and the ability to silence several genes simultaneously should enhance our ability to create novel traits in plants.

Gene Expression Regulation, Plant↗
PubMed2006

The PsEND1 promoter: a novel tool to produce genetically engineered male-sterile plants by early anther ablation.

PsEND1 is a pea anther-specific gene that displays very early expression in the anther primordium cells. Later on, PsEND1 expression becomes restricted to the epidermis, connective, endothecium and middle layer, but it is never observed in tapetal cells or microsporocytes. We fused the PsEND1 promoter region to the cytotoxic barnase gene to induce specific ablation of the cell layers where the PsEND1 is expressed and consequently to produce male-sterile plants. Expression of the chimaeric PsEND1::barnase gene in two Solanaceae (Nicotiana tabacum and Solanum lycopersicon) and two Brassicaceae (Arabidopsis thaliana and Brassica napus) species, impairs anther development from very early stages and produces complete male-sterile plants. The PsEND1::barnase gene is quite different to other chimaeric genes previously used in similar approaches to obtain male-sterile plants. The novelty resides in the use of the PsEND1 promoter, instead of a tapetum-specific promoter, to produce the ablation of specific cell lines during the first steps of the anther development. This chimaeric construct arrests the microsporogenesis before differentiation of the microspore mother cells and no viable pollen grains are produced. This strategy represents an excellent alternative to generate genetically engineered male-sterile plants, which have proved useful in breeding programmes for the production of hybrid seeds. The PsEND1 promoter also has high potential to prevent undesirable horizontal gene flow in many plant species.

Arabidopsis↗
PubMed2003

[Breeding transgenic plants with safe or no selective markers].

The bio-safety of selective markers in transgenic plants has been a hot spot in the field of plant genetic engineering. To solve the problem of selective markers in the transgenic plants, two means of producing transgenic plants have been developed. One is the utilization of bio-safe positive selective markers which are genes mainly related to metabolism of auxins and carbohydrates. The other is the establishment of transformation systems allowing marker genes to be eliminated from the transgenic plants, which include co-ransformation, double T-DNA border vectors, site-specific recombination and transposition. All these approaches of plant genetic engineering will benefit breeding transgenic plants with bio-safety.

English Abstract↗
PubMed2002

Metabolic engineering of osmoprotectant accumulation in plants.

Drought and salinity are among the worst scourges of agriculture. One effective mechanism to reduce damage from these stresses is the accumulation of high intracellular levels of osmoprotectant compounds. These compounds include proline, ectoine, betaines, polyols, and trehalose and have evolved in many different organisms. Since some crop plants have low levels of these osmoprotectants or none at all, engineering osmoprotectant biosynthesis pathways is a potential way to improve stress tolerance. First-generation engineering work--much of it with single genes--has successfully introduced osmoprotectant pathways into plants that lack them naturally, and this has often improved stress tolerance. However, the engineered osmoprotectant levels are generally low and the increases in tolerance commensurately small. To get beyond trace levels of osmoprotectants and marginal tolerance increments we need to use flux measurements to diagnose what limits osmoprotectant levels in engineered plants and to use iterative cycles of engineering to overcome these limitations.

Amino Acids, Diamino↗
PubMed1998

Impairment of tapetum and mitochondria in engineered male-sterile tobacco plants.

Flowers of tobacco transformed with an unedited copy of the mitochondrial atp9 gene sequence fused to the yeast coxIV mitochondrial targeting presequence, showed several anther abnormalities leading to pollen abortion. The gene was expressed in vegetative and reproductive tissues of the plant. Cytological analysis revealed that tapetum development was impaired. Mitochondria of the tapetum cells were severely affected showing characteristic signs of degeneration: loss of cristae and swelling. These mitochondrial modifications were correlated with the presence of the transcript and translated product of the 'unedited' atp9 and a significant decrease in oxygen consumption in non-photosynthetic tissues. The main effect of the unedited atp9 expression in transgenic plants was male sterility.

Arabidopsis Proteins↗
PubMed1990

Wound-inducible potato inhibitor II genes: enhancement of expression by sucrose.

Expression of a chimeric potato Inhibitor II-CAT gene in transgenic tobacco plants was enhanced 50-fold when leaf tissue was floated on solutions containing 1% sucrose. The expression of the chimeric gene was also enhanced when leaf sections were floated on solutions of glucose, fructose, and maltose, but not when floated on solutions of mannitol. The increased expression due to sucrose was found to be correlated with an increase in CAT mRNA. Thus, the carbohydrates or their metabolic products may control Inhibitor II gene expression by regulating transcription. Levels of potato Inhibitor II proteins in leaf sections from young potato plants floated on 3% sucrose solutions increased 3-fold compared to leaf sections floated on water, supporting the possibility that sucrose may have a role in regulating or enhancing the expression of wound-inducible proteinase inhibitor genes in potato tissues. It is suggested that the Inhibitor II gene and perhaps other genes regulated by sucrose may contain a specific 'sucrose enhancer' that strongly increases transcription of genes already active at low levels.

Carbohydrates↗
PubMed2006

Loss and recovery of protein productivity in genetically modified plant cell lines.

This paper addresses the problem of decreasing protein expression levels in genetically modified plant cells. A modeling approach was used to explain the loss of productivity over successive generations. Using this model, productivity losses were simulated for two cell lines. Although the lines were relatively stable, the protein production level could decrease by more than 80% after a large number of generations. Motivated by this problem, a dispersion method was developed to isolate productive cells from existing cell suspensions. Dilution of transgenic cells in a feeder layer of nonproducing cells at a ratio of 1:1000 facilitated the recovery of distinct, separate daughter colonies. Applying this method, it was possible to recover high producing cell lines.

Cell Line↗
PubMed2004

Ethanol-inducible gene expression: first step towards a new green revolution?

The introduction of dwarf varieties of cereals was fundamental to the green revolution, but in the post-genomic era, the manipulation of plant morphology could be more sophisticated. A recent publication by Tahar Ait-ali et al. describes the use of the ethanol-inducible transgene expression system to re-examine plant architecture, and the genes that determine it. Their findings have implications for the manipulation of plant height and yield, and demonstrate the efficacy of regulated transgene expression for functional genomics.

Agriculture↗
PubMed2003

Transgenic plants with altered ethylene biosynthesis or perception.

The plant hormone ethylene is an essential signaling molecule involved in many plant processes including: germination, flower development, fruit ripening and responses to many environmental stimuli. Moreover, large increases in ethylene levels occur during plant stress responses, fruit ripening and flower wilting. Manipulation of ethylene biosynthesis or perception allows us to modulate these processes and thereby create plants with more robust and/or desirable traits, giving us a glimpse into the role of ethylene in the plant. Here, recent and landmark advances in genetic alteration of members of the ethylene pathway in plants and the physiological consequences of these alterations are examined.

Arabidopsis↗