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At least 19 recordsLinked to original sources
PubMed2002

Characterization of expression of Puumala virus nucleocapsid protein in transgenic plants.

Transgenic plants expressing a foreign gene are a suitable system for the production of relevant immunogens in high amounts that can be used for the development of a new generation of vaccines against a variety of infectious diseases. In the present study, the expression of the nucleocapsid (N) protein of hantavirus serotype Puumala in tobacco and potato plants was investigated. Transgenic tobacco and potato plants were generated and established. These transgenic plants expressed the N protein of Puumala virus strain CG-1820. No major differences were observed when the phenotype and growth rates of transgenic plants were compared to those of normal plants. However, it was found that the leaves of transgenic tobacco plants were more slender and the tubers of transgenic potato plants were smaller than those in normal plants. In order to investigate the distribution of the expression of the foreign gene in transgenic plants, the proteins of leaves and roots of the individual transgenic tobacco and potato plants were examined by Western blot analyses. It was found that all transgenic tobacco and potato plants expressed the N protein in the leaves, whereas transgenic potato plants are able to significantly express the viral proteins also in the tubers and roots. The antigens were expressed at a level of 1 ng of protein/5 microg of dried leaves. The hantaviral recombinant N proteins obtained from transgenic tobacco and potato plants were able to elicit specific humoral and mucosal immune responses when administered intraperitoneally or orally to rabbits and mice. The expression of viral proteins in plants has two major advantages compared to other expression systems: firstly, there is no risk of contamination with mammalian viruses or other pathogens, and secondly, the production of high amounts of antigens is cheap and therefore of great economic interest.

Nucleocapsid↗
PubMed1990

Regulation of nuclear genes encoding chloroplast proteins in transgenic plants.

Transgenic plants have been particularly useful in studying nuclear genes encoding for photosynthetic functions. The expression of these genes and their chimeric constructs in transgenic plants faithfully mimics their natural counterparts. The use of sensitive chimeric reporter genes has enabled localizing the activity of genes encoding photosynthetic proteins to individual cells. Cab and rbcS transgenes have been shown to retain sensitivity to light quality, which is modulated by phytochrome. Conditional light activation under the influence of a circadian rhythm has been shown for Cab transgenes. Transgenic plants containing truncated promoters have helped delineate cis-regulatory positive and negative elements involved in light-mediated transcriptional induction and tissue specificity.

Base Sequence↗
PubMed2005

Concurrent use of transgenic plants expressing a single and two Bacillus thuringiensis genes speeds insect adaptation to pyramided plants.

Transgenic plants expressing insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) were grown on over 13 million ha in the United States and 22.4 million ha worldwide in 2004. Preventing or slowing the evolution of resistance by insects ("resistance management") is critical for the sustainable use of Bt crops. Plants containing two dissimilar Bt toxin genes in the same plant ("pyramided") have the potential to delay insect resistance. However, the advantage of pyramided Bt plants for resistance management may be compromised if they share similar toxins with single-gene plants that are deployed simultaneously. We tested this hypothesis using a unique model system composed of broccoli plants transformed to express different Cry toxins (Cry1Ac, Cry1C, or both) and a synthetic population of the diamondback moth (Plutella xylostella) carrying genes for resistance to Cry1Ac and Cry1C at frequencies of approximately 0.10 and 0.34, respectively. After 24-26 generations of selection in the greenhouse, the concurrent use of one- and two-gene plants resulted in control failure of both types of Bt plants. When only two-gene plants were used in the selection, no or few insects survived on one- or two-gene Bt plants, indicating that concurrent use of transgenic plants expressing a single and two Bt genes will select for resistance to two-gene plants more rapidly than the use of two-gene plants alone. The results of this experiment agree with the predictions of a Mendelian deterministic simulation model and have important implications for the regulation and deployment of pyramided Bt plants.

Adaptation, Biological↗
PubMed2004

Problems in monitoring horizontal gene transfer in field trials of transgenic plants.

Transgenic crops are approved for release in some countries, while many more countries are wrestling with the issue of how to conduct risk assessments. Controls on field trials often include monitoring of horizontal gene transfer (HGT) from crops to surrounding soil microorganisms. Our analysis of antibiotic-resistant bacteria and of the sensitivity of current techniques for monitoring HGT from transgenic plants to soil microorganisms has two major implications for field trial assessments of transgenic crops: first, HGT from transgenic plants to microbes could still have an environmental impact at a frequency approximately a trillion times lower than the current risk assessment literature estimates the frequency to be; and second, current methods of environmental sampling to capture genes or traits in a recombinant are too insensitive for monitoring evolution by HGT. A model for HGT involving iterative short-patch events explains how HGT can occur at high frequencies but be detected at extremely low frequencies.

Ecosystem↗
PubMed1997

Encapsidation of potyviral RNA in various forms of transgene coat protein is not correlated with resistance in transgenic plants.

Transgenic plants expressing either bean yellow mosaic potyvirus or chimeric potyvirus coat protein (CP) were inoculated with various potyviruses. Antigen-coated plate, indirect enzyme-linked immunosorbent assay and immunoelectron microscopy of virus purified from transgenic plants showed that progeny virions contained from < 1% to as much as 25% transgenic CP. Different levels of transcapsidation may reflect the extent of compatibility between transgene CP and the viral CP.

Amino Acid Sequence↗
PubMed1997

Recombinant proteins from transgenic plants.

Transgenic plants can express a wide variety of foreign genes and offer the opportunity of large-scale protein production in agricultural systems. The recombinant protein can serve both ex situ and in situ purposes. Due to significant progress in plant molecular biology, many different plant species can now be transformed and are even capable of producing very complex proteins such as antibodies or vaccines. Furthermore, recombinant proteins can mediate resistance against microbial pathogens, such as fungi or viruses, or protect transgenic plants from insect pests.

Journal Article↗
PubMed1997

[The safety and usefulness of transgenic plants].

Transgenic crop plants, used in food and feed production, carry different beneficial transgenes, mostly for resistance to pests, herbicides and diseases. All new transgenic plant varieties, the genes they carry and their products have been thoroughly tested before released for agriculture and even more for marketing. Genetically modified organisms carry the same risk as any other organism. Food derived from genetically modified organisms due to legal regulation is most controlled and therefore most safe food ever placed on the market. In future, transgenic plants offer many new possibilities also for medical use, like plant vaccines, antibiotics and rare proteins of clinical importance produced by plants.

Consumer Product Safety↗
PubMed2002

Human anti-rhesus D IgG1 antibody produced in transgenic plants.

Transgenic plants represent an alternative to cell culture systems for producing cheap and safe antibodies for diagnostic and therapeutic use. To evaluate the functional properties of a 'plantibody', we generated transgenic Arabidopsis plants expressing full-length human IgG1 against the Rhesus D antigen, which is responsible for alloimmunization of RhD- mothers carrying an RhD+ fetus. Anti-RhD extracted from plants specifically reacted with RhD+ cells in antiglobulin technique, and elicited a respiratory burst in human peripheral blood mononuclear cells. Plant-derived antibody had equivalent properties to CHO cell-produced anti-RhD antibody, indicating its potential usefulness in diagnostic and therapeutic programs.

Agglutination Tests↗
PubMed1993

Genetically engineered protection against viruses in transgenic plants.

Transgenic plants carrying nucleotide sequences derived from plant viruses can exhibit increased resistance to viral disease. Many viral sequences confer some level of either resistance to infection or suppression of disease symptoms (tolerance). These include segments of viral genomes encoding capsid or coat proteins, sequences encoding proteins that are or may be subunits of the viral replicase, sequences incapable of encoding proteins, entire genomes of defective interfering viruses and satellite viruses, and complete genomes of mild strains of virus. The transgene may act on initiation of infection, replication of virus, spread of the infection throughout the plant, and symptom development. More than one of these processes can be impaired by a single transgene derived from a single viral gene. The level of protection ranges from very low to high, while the breadth of protection ranges from very narrow, where protection is only observed against closely related strains of the virus from which the transgene was derived, to moderately broad, extending to other viruses. Data are insufficient to establish a molecular mechanism of resistance for most of the described examples. In addition, although the use of a particular segment of the viral genome confers resistance in one virus-host system, analogous sequences from a different virus in another host may be ineffective.

Genetic Engineering↗
PubMed2004

[Molecular strategies for decreasing the gene flow of transgenic plants].

Transgenic plants can transfer foreign genes through pollen or seed to related plant species. This may cause potential harm to ecological environment. How to decrease the gene flow is drawing a growing public attention. The approaches for decreasing the gene flow include chloroplast transformation, pollen sterility, seed sterility, cleistogamy, apomixis, temporal control, and transgenic mitigation. The theoretical basis, advantages and disadvantages, and usage status of these approaches are presented in this review.

Chloroplasts↗
PubMed2005

Safety evaluation of the phosphinothricin acetyltransferase proteins encoded by the pat and bar sequences that confer tolerance to glufosinate-ammonium herbicide in transgenic plants.

Transgenic plant varieties, which are tolerant to glufosinate-ammonium, were developed. The herbicide tolerance is based upon the presence of either the bar or the pat gene, which encode for two homologous phosphinothricin acetyltransferases (PAT), in the plant genome. Based on both a review of published literature and experimental studies, the safety assessment reviews the first step of a two-step-approach for the evaluation of the safety of the proteins expressed in plants. It can be used to support the safety of food or feed products derived from any crop that contains and expresses these PAT proteins. The safety evaluation supports the conclusion that the genes and the donor microorganisms (Streptomyces) are innocuous. The PAT enzymes are highly specific and do not possess the characteristics associated with food toxins or allergens, i.e., they have no sequence homology with any known allergens or toxins, they have no N-glycosylation sites, they are rapidly degraded in gastric and intestinal fluids, and they are devoid of adverse effects in mice after intravenous administration at a high dose level. In conclusion, there is a reasonable certainty of no harm resulting from the inclusion of the PAT proteins in human food or in animal feed.

Acetyltransferases↗
PubMed2002

Economic, ecological, food safety, and social consequences of the deployment of bt transgenic plants.

Transgenic plants expressing insecticidal proteins from the bacterium, Bacillus thuringiensis (Bt), are revolutionizing agriculture. Bt, which had limited use as a foliar insecticide, has become a major insecticide because genes that produce Bt toxins have been engineered into major crops grown on 11.4 million ha worldwide in 2000. Based on the data collected to date, generally these crops have shown positive economic benefits to growers and reduced the use of other insecticides. The potential ecological and human health consequences of Bt plants, including effects on nontarget organisms, food safety, and the development of resistant insect populations, are being compared for Bt plants and alternative insect management strategies. Scientists do not have full knowledge of the risks and benefits of any insect management strategies. Bt plants were deployed with the expectation that the risks would be lower than current or alternative technologies and that the benefits would be greater. Based on the data to date, these expectations seem valid.

Animals↗
PubMed2000

Potato mop-top virus RNA can move long distance in the absence of coat protein: evidence from resistant, transgenic plants.

Transgenic expression of a translatable version of the Potato mop-top virus (PMTV) coat protein (CP) gene (encoded by RNA 3) in Nicotiana benthamiana prevented production of symptoms and infective virus particles. RNAs 1 and 2 accumulated in inoculated and systemic leaves but, apart from small amounts of CP transgene RNA transcript, no genomic-length RNA 3 was found. Crude leaf extracts from inoculated plants were not infective. However, when RNA extracts from such transgenic plants were inoculated to nontransgenic N. benthamiana and N. clevelandii, RNA 1 and RNA 2 replicated in systemic leaves of both species in the absence of RNA 3 and virus particles, but symptoms did not develop. We suggest that the triple-gene block proteins of PMTV (encoded by RNA 2) represent a class of long-distance RNA movement factors.

Blotting, Northern↗
PubMed1988

In vivo import of plastocyanin and a fusion protein into developmentally different plastids of transgenic plants.

Transgenic tomato plants that constitutively express a foreign plastocyanin gene were used to study protein transport in different tissues. Normally expression of endogenous plastocyanin genes in plants is restricted to photosynthetic tissues only, whereas this foreign plastocyanin protein is found to be present in all tissues examined. The protein is transported into the local plastids in these tissues and it is processed to the mature size. We conclude that plastids of developmentally different tissues are capable of importing precursor proteins that are normally not found in these tissues. Most likely such plastids, though functionally and morphologically differentiated, have similar or identical protein import mechanisms when compared to the chloroplasts in green tissue.

Chloroplasts↗
PubMed2005

[Advances in the Study on Marker Genes in transgenic Plants.].

Plant transgenic engineering is becoming more and more important in the world. The safety of selectable marker genes in the transgenic plants has been noticed widely. The new advances of selectable markers in transgenic plants were reviewed in this paper in three aspects. The first is the establishment of transformation systems allowing resistant marker genes to be eliminated from the transgenic plants, including co-transformation, site-specific recombination and transposition, as well as other methods. In these ways, the transgenes can be inserted into transgenic plants more than once. The second is the utilization and development of bio-safe positively selective marker genes, mainly referred to the carbohydrates metabolism genes, the stress- resistant enzymatic genes and the green fluorescent protein(GFP) gene. At the same time, the mercuric reductase genes, the key genes for chloroplast synthesis and other genes should also be quickly developed as markers. The third is the establishment of marker-free and skelecton-free transformation vector systems, which are efficient and simple. The prospects in application of these novel methods, marker free and safe selectable markers are also viewed in the article.

Genetic Markers↗
PubMed2006

The Lem2 gene promoter of barley directs cell- and development-specific expression of gfp in transgenic plants.

Transgenic approaches to combating fungal pathogens, such as Fusarium graminearum, require the targeting of antifungal gene expression in tissues of developing seed spikes of cereal grains, especially lemmas and epicarps. The Lem2 gene of barley encodes a lectin-like protein that is strongly up-regulated by salicylic acid and is preferentially expressed in lemmas, paleas (lemma/palea) and coleoptiles. Transient expression studies have indicated that the proximal -75/+70 region (relative to the transcription start site) determines organ specificity. In the present study, Golden Promise barley stably transformed with Morex Lem2 promoter/gfp reporter constructs displayed cell- and development-specific expression of gfp (green fluorescent protein gene). This expression corresponded to the expression seen in Northern blots of Morex organs. Under the full-length promoter, strong GFP fluorescence was observed in the lemma/palea, glumes, coleoptile, auricle and ligule. Weak GFP fluorescence was also observed in the rachis, tips of primary leaves and the leaf sheath. Unexpectedly, strong expression occurred in the epicarp, even though Lem2 is not expressed in this organ in Morex. Studies showed that the Lem2 promoter is more highly methylated in the epicarp than in the lemma of Morex. In the lemma/palea, gfp underwent a temporal shift in expression from the mesophyll to specialized epidermal cork cells. Similar to the lemma/palea, expression in the leaf sheath was localized in the cork cells. Progressive 5' deletions of the promoter to nucleotide -75 gradually reduced the level of gfp expression, but tissue- and cell-specific expression was retained.

5' Flanking Region↗
PubMed1994

[Molecular genetics and biotechnology in medicinal plants: studies by transgenic plants].

The advances in molecular genetics and biotechnology in the field of medicinal plant research are discussed with focusing on the works using transgenic plants. Differentiated organ cultures and transgenic teratomas, incited by the infection with mutants of Agrobacterium Ti and Ri plasmids, were established in quinolizidine-alkaloid producing plants and Solanaceae plants. These cultured cells were used for the production and bioconversion of specific alkaloids produced in these plants. The methods of integration of foreign genes into medicinal plants were developed using an Ri binary vector. The mode of gene expression driven by TR1'-2' promoters was elucidated in transgenic medicinal plants, e.g., Nicotiana tabacum, Glycyrrhiza uralensis, Digitalis purpurea and Atropa belladonna. The genes for herbicide resistance, mammalian cytochrome P450 and bacterial beta-hydroxydecanoylthioester dehydrase were transferred and expressed in plants either to confer herbicide-resistant trait or to change the pattern of metabolites. The cDNA clones encoding cysteine synthase responsible for sulfur assimilation and biosynthesis of non-protein amino acids were isolated and characterized from Spinacea oleracea and Citrullus vulgaris. The functional lysine residue was identified by site-directed mutagenesis experiments. An over-expression system in Escherichia coli was constructed for the bacterial production of the plant specific non-protein amino acids. We made transgenic N. tabacum integrated with sense- and antisense-constructs of cysteine synthase cDNA driven by cauliflower mosaic virus 35S promoter for the purpose of genetic manipulation of biosynthetic flow of cysteine in plants. The future prospects of medicinal plant research are also discussed in the context of modern plant molecular biology.

Alkaloids↗
PubMed1995

Broad resistance to plant viruses in transgenic plants conferred by antisense inhibition of a host gene essential in S-adenosylmethionine-dependent transmethylation reactions.

S-Adenosylhomocysteine hydrolase (SAHH) is a key enzyme in transmethylation reactions that use S-adenosylmethionine as the methyl donor. Because of the importance of SAHH in a number of S-adenosylmethionine-dependent transmethylation reactions, particularly the 5' capping of mRNA during viral replication, SAHH has been considered as a target of potential antiviral agents against animal viruses. To test the possibility of engineering a broad type of resistance to plant viruses, we expressed the antisense RNA for tobacco SAHH in transgenic tobacco plants. As expected, transgenic plants constitutively expressing an anti-sense SAHH gene showed resistance to infection by various plant viruses. Among those plants, about half exhibited some level of morphological change (typically stunting). Analysis of the physiological change in those plants showed that they contained excess levels of cytokinin. Because cytokinin has been found to induce acquired resistance, there is also a strong possibility that the observed resistance was induced by cytokinin.

Journal Article↗