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At least 739 records · Page 41Linked to original sources

PubMed2005

Molecular evidence of barley yellow dwarf virus replication/movement suppressed by the resistance gene Bdv2.

A wheat-Thinopyrum intermedium translocation line YW642 possesses the resistance to GAV serotype of barley yellow dwarf virus (BYDV), in which the resistance gene Bdv2 is derived from the chromosome 7X of Thinopyrum intermedium group 7. It is interesting to analyze BYDV accumulation content in the resistant and susceptible wheat plants for controlling BYDV disease and understanding the resistance mechanism against BYDV. In the paper, semi-quantitative reverse-transcription PCR (RT-PCR) was used to detect and quantify BYDV-GAV in the resistant and susceptible plants using specific primers for the coat protein (CP) and RNA-dependent RNA polymerase (RdRp) genes of BYDV-GAV serotype. On the inoculation site, the amount of the virus in the resistant wheat line (YW642) was much lower compared to the susceptible sib line (YW641). There was small amount of the virus could be detected in YW642 at 2-5 days post infestation (dpi), afterwards the amount of virus decreased and no virus could be detected at 14 and 16 dpi. In the uninoculated upper leaves, no BYDV was detected in YW642 from 1 to 14 dpi, while the virus could be detected at 3 dpi and then accumulated rapidly in YW641. These results showed at molecular level that the replication and/or movement of BYDV-GAV were strongly suppressed in YW642, presumably owing to the action of the BdV2 gene.

Chromosome Mapping↗

PubMed2006

[Initial identification of quantitative trait loci controlling resistance to banded leaf and sheath blight at elongating and heading date in maize].

The genetic linkage map was constructed with 146 SSR markers based on a maize population consisting of 229 F2 individuals from the cross R15 (resistant) x 478 (susceptible), covering 1666cM on a total of ten chromosomes, with an average interval length of 11.4 cM. The disease index from the population of 229 F24 lines were evaluated for BLSB resistance under artificial inoculation at elongating stage and heading date. With the method of composite interval mapping (CIM) described in QTL cartographer v2.0 procedure, 9 QTLs among of 17 QTLs were identified on 1, 2, 3, 4, 5, 6 and 10 chromosomes at Jointing Stage, accounting for 3.72% to 9.26% of the phenotypic variance. The other 10 QTLs were identified on 2, 3, 4, 5, 6, 8 and 9 chromosomes at elongating stage and heading date, accounting for 4.27% to 9.27% of the phenotypic variance. Among of them, two QTLs were detected at two stages, which were located between bnlgl600-umc1818 and umc1006-umc1723 on chromosome 2 and 6, respectively. The result indicated that the significant difference about QTL Controlling Resistance between the two stages had a close connection with Developing Stages, which was showed on the resistance of banded leaf and sheath blight in maize. So this result provided new information to the resistance breeding of maize.

Chromosome Mapping↗

PubMed2025

The Arabidopsis TIRome informs the design of artificial TIR (Toll/interleukin-1 receptor) domain proteins.

The TIR (Toll/interleukin-1 receptor) domain is an ancient protein module that functions in immune and cell death responses across the Tree of Life. TIR domains encoded by plants and prokaryotes function as enzymes to produce diverse small molecule immune signals. Plant genomes can encode hundreds of TIR-domain containing proteins-many of which confer important agricultural disease resistance as TIR-NLR (nucleotide-binding, leucine-rich repeat) immune receptors. Despite their importance, how natural variation influences TIR enzymatic output and immunity-associated cell death is largely unexplored. We assayed a complete collection of the TIR domains of Arabidopsis thaliana Col-0 (the "AtTIRome") to explore variation in TIR metabolite production and cell death signaling. Roughly half of the AtTIRome triggered cell death in transient assays. Artificial TIR proteins designed based on consensus sequences of the AtTIRome's cell death phenotypic classes revealed polymorphisms controlling variation in TIR cell death elicitation and metabolite production. Structure-function analyses of artificial TIRs revealed that natural variation in the "BB-loop", a flexible region overlying the catalytic pocket, determines differences in function across Arabidopsis TIR-containing proteins. We further demonstrate that artificial TIRs are functional on an NLR chassis and that BB-loop variation can tune the activity of a natural TIR-NLR protein. These findings shed light on the diversity of TIR outputs and reveal methods to design and engineer TIR-based immune receptors.

Arabidopsis↗

PubMed2005

Oral immunotherapy against a pollen allergy using a seed-based peptide vaccine.

Peptide immunotherapy using dominant T-cell epitopes is safer and more effective than conventional immunotherapy for the treatment of immunoglobulin E (IgE)-mediated allergic diseases. When allergenic T-cell epitope peptides are expressed in the edible part of transgenic plants, successful mucosal immune tolerance to these allergens may be attainable by the consumption of these plants. In this study, we generated transgenic rice seed that accumulated high concentrations (about 60 microg per grain) of polypeptide consisting of seven dominant human T-cell epitopes derived from the Japanese cedar pollen allergens, Cry j 1 and Cry j 2, in the endosperm. Oral administration of these transgenic rice seeds to B10.S mice before or after they were immunized with Cry j 1 holoprotein reduced not only their T-cell proliferative response to Cry j 1, but also their serum IgE levels, proving the efficacy of oral immunotherapy for the treatment of pollinosis.

Journal Article↗

PubMed2006

[Protective immune response of guinea pigs against challenge with foot and mouth disease virus by immunization with foliar extracts from transgenic tomato plants expressing the FMDV structural protein VP1].

The plant constitutive expression vector pBin438/VP1 for VP1 gene of foot-and-mouth disease virus strain O/ China/99 was constructed. Mediated with Agrobacterium tumefaciens GV3101 harboring pBin438/VP1, VP1 gene was transferred into cotyledons of tomato. After selected by Kanamysin, sixty resistant lines were obtained. The integration and transcription of the VP1 gene in transformed plants was detected by PCR and RT-PCR. After being detected by sandwich-ELISA assays, about 40% transformed plants confirmed to express the recombinant protein. The leave extracts of two positive lines were respectively emulsified in Freund's adjuvant and guinea pigs were intramuscular inoculation at days 0, 15 and 30d. According to the sera antibody levels and the protection of the vaccinated guinea pigs against challenge with 100ID50 FMDV, probed into the immunogenicity of the target protein expressed in transgenic plants. Experimental results showed that the plant expression vector was successfully constructed. PCR and RT-PCR analyses confirmed VP1 gene was transformed into tomato plants and got expression at the transcription levels. The expressed VP1 protein of FMDV, which was identified by ELISA and Western blot, can be specifically recognized by polyclonal antibodies against FMDV. Indirect-ELISA antibody titers reached 1:64 twenty-one days after the third inoculation. In the challenge test, the protection against FMDV challenge in two groups was 80% and 40% respectively. The immunization test in guinea pigs indicated that the expression product of transgenic tomato plants had immunogenicity and could effectively induce the specific antibodies against FMDV.

Animals↗

PubMed2003

[Study on the preparing of polyclonal antibodies against plant-selected maker gene hpt expression protein by DNA immunization].

AIM: To prepare the polyclonal antibodies (pAbs) against HPT, a kind of plant-selected maker gene encoding protein, by DNA immunization technique and explore the influencing factors for this gene immunization. METHODS: The coding sequence of hpt was cloned into eukaryotic expression vector pCDNA3. The sequence of the plasmid pCDNA3-HPT was demonstrated by restricting enzyme digestion analysis and DNA sequencing. The sequence-correct recombinant plasmids were purified and used to immunize BALB/c mice. The titer and specificity of antisera were detected by ELISA and Western blot, respecitively. RESULTS: No pAb against HPT was detected following three immunization with hpt genes. Then mice were divided into three groups when the forth booster immunization was carried out: 1st group (immunization with the endotoxin-free recombinant plasmids), 2nd group (immunization with (His)(6)-HPT fusion protein expressed in E.coli) and 3rd group (immunization with the same plasmids as before mentioned). As a result, the pAb titer of the 1st group mice increased to 1:200, and the that of 2nd group was up to 1:2 000. Yet the 3rd group detected no anti-HPT antibody. Western blot analysis had proved that antisera of the first two groups could produce specific binding reaction to the purified GST-HPT, (His)(6)-HPT protein and their expressed product (bacterial protein). CONCLUSION: We have got successfully the specific pAb against HPT by DNA immunization, but its titer is yet unsatisfactory, inferring that the character of the hpt gene self and its expression level may play an important role. In order to raise level of serum antibody prepared by DNA immunization, the farther study on various influencing factors still need to be performed.

Animals↗

PubMed1998

Efficacy of a food plant-based oral cholera toxin B subunit vaccine.

Transgenic potatoes were engineered to synthesize a cholera toxin B subunit (CTB) pentamer with affinity for GMI-ganglioside. Both serum and intestinal CTB-specific antibodies were induced in orally immunized mice. Mucosal antibody titers declined gradually after the last immunization but were restored following an oral booster of transgenic potato. The cytopathic effect of cholera holotoxin (CT) on Vero cells was neutralized by serum from mice immunized with transgenic potato tissues. Following intraileal injection with CT, the plant-immunized mice showed up to a 60% reduction in diarrheal fluid accumulation in the small intestine. Protection against CT was based on inhibition of enterotoxin binding to the cell-surface receptor GMI-ganglioside. These results demonstrate the ability of transgenic food plants to generate protective immunity in mice against a bacterial enterotoxin.

Animals↗

PubMed2003

Structural characterization of plant-derived hepatitis B surface antigen employed in oral immunization studies.

Several subunit vaccine antigens have been successfully expressed in plants and recently the hepatitis B surface antigen (HBsAg), expressed in potatoes, was shown to be orally immunogenic in animal studies. However, to date, a detailed analysis of the plant-derived antigen is lacking. Herein, we comprehensively characterize the structure and post-translational processing of HBsAg from potato tuber and two plant cell suspension cultures. The HBsAg was found to accumulate intracellularly as tubular structures, with a complex size distribution, differing substantially from the virus-like particle (VLP) preparations of the current commercial vaccines. Extensive disulfide-bond cross-linking, which is important for immunogenicity, was evident and 21-37% of total HBsAg protein displayed epitopes which correlate with vaccine potency. The significance of these results with regard to the production of cost-effective orally delivered vaccines is discussed.

Administration, Oral↗

PubMedDate not supplied

[Pathogen-induced plant proteins].

Pathogen-induced plant proteins are classified by their functional characteristics: (a) involvement in plant cell signaling; (b) inhibition of enzymes excreted by the pathogens; (c) stabilization of plant cell walls or ability to trigger apoptosis; (d) enzymatic activity producing lysis of cell walls of pathogenic fungi and bacteria; (e) enzymatic activity in metabolic pathways of phenylpropane and terpene phytoalexins; and (f) ability to affect the pathogens directly, by disturbing the function of their cell membranes or by inactivating their ribosomes. Examples of transgenic plants with increased immunity against pathogens are also provided.

Plant Cells↗

PubMed2025

Genetic suppressors of the growth-immunity trade-off in the Arabidopsis salicylic acid-accumulating dmr6 dlo1 mutant.

Plants actively suppress growth and development upon activation of immunity. In turn, when pathogen attack has subsided, immune responses are suppressed again. Phytohormones play an important role in regulating this balance and the growth-immunity trade-off in general. The trade-off is evident in the Arabidopsis dmr6 dlo1 mutant, which accumulates the immune-activating phytohormone salicylic acid (SA) to high levels, resulting in high disease resistance but repression of growth. Little is known about the SA-induced growth trade-off mechanism. In this study, we performed a genetic suppressor screen on the dmr6 dlo1 double mutant to select mutants with reduced growth repression and identify suppressors of the SA-mediated trade-off. We identified 7 independent zund (giant) mutants, with restored growth but retained resistance to downy mildew. Through bulked segregant analysis and whole-genome sequencing (BSA-seq), we identified three mutant alleles of MED15a, an NPR1 allele, one ICS1/SID2 allele, and a PAD4 splice defect. Genetic complementation of mutants confirmed the roles of these genes in the SA-mediated growth-immunity trade-off. We discuss their application in tweaking SA signaling to optimize the balance between growth and immunity that is important when deploying immunity traits in breeding.

Arabidopsis↗

PubMed2006

Plant responses to UV radiation and links to pathogen resistance.

Increased incident ultraviolet (UV) radiation due to ozone depletion has heightened interest in plant responses to UV because solar UV wavelengths can reduce plant genome stability, growth, and productivity. These detrimental effects result from damage to cell components including nucleic acids, proteins, and membrane lipids. As obligate phototrophs, plants must counter the onslaught of cellular damage due to prolonged exposure to sunlight. They do so by attenuating the UV dose received through accumulation of UV-absorbing secondary metabolites, neutralizing reactive oxygen species produced by UV, monomerizing UV-induced pyrimidine dimers by photoreactivation, extracting UV photoproducts from DNA via nucleotide excision repair, and perhaps transiently tolerating the presence of DNA lesions via replicative bypass of the damage. The signaling mechanisms controlling these responses suggest that UV exposure also may be beneficial to plants by increasing cellular immunity to pathogens. Indeed, pathogen resistance can be enhanced by UV treatment, and recent experiments suggest DNA damage and its processing may have a role.

DNA Damage↗

PubMed2002

Treatment of silymarin, a plant flavonoid, prevents ultraviolet light-induced immune suppression and oxidative stress in mouse skin.

It is well documented that ultraviolet (UV) light-induced immune suppression and oxidative stress play an important role in the induction of skin cancers. Earlier, we have shown that topical treatment of silymarin, a plant flavonoid from milk thistle (Silybum marianum L. Gaertn.), to mouse skin prevents photocarcinogenesis, but the preventive mechanism of photocarcinogenesis in vivo animal system by silymarin is not well defined and understood. To define the mechanism of prevention, we employed immunostaining, analytical assays and ELISA which revealed that topical treatment of silymarin (1 mg/cm2 skin area) to C3H/HeN mice inhibits UVB (90 mJ/cm2)-induced suppression of contact hypersensitivity (CHS) response to contact sensitizer dinitrofluorobenzene. Prevention of UVB-induced suppression of CHS by silymarin was found to be associated with the inhibition of infiltrating leukocytes, particularly CD11b+ cell type, and myeloperoxidase activity (50-71%). Silymarin treatment also resulted in significant reduction of UVB-induced immunosuppressive cytokine interleukin-10 producing cells and its production (58-72%, p<0.001). Topical treatment of silymarin also resulted in significant reduction of the number of UVB-induced H2O2 producing cells and inducible nitric oxide synthase expressing cells concomitant with decrease in H2O2 (58-65%, p<0.001) and nitric oxide (65-68%, p<0.001) production. Together, these data suggest that prevention of UVB-induced immuno-suppression and oxidative stress by silymarin may be associated with the prevention of photocarcinogenesis in mice. The data obtained from this study also suggest: i) phase-I clinical trial of silymarin in high skin cancer risk human population and ii) development of sunscreen containing silymarin as an antioxidant (chemopreventive agent) or silymarin can be supplemented in skin care products.

Animals↗

PubMedDate not supplied

A dynamic mathematical model to clarify signaling circuitry underlying programmed cell death control in Arabidopsis disease resistance.

Plant cells undergo programmed cell death in response to invading pathogens. This cell death limits the spread of the infection and triggers whole plant antimicrobial and immune responses. The signaling network connecting molecular recognition of pathogens to these responses is a prime target for manipulation in genetic engineering strategies designed to improve crop plant disease resistance. Moreover, as alterations to metabolism can be misinterpreted as pathogen infection, successful plant metabolic engineering will ultimately depend on controlling these signaling pathways to avoid inadvertent activation of cell death. Programmed cell death resulting from infection of Arabidopsis thaliana with Pseudomonas syringae bacterial pathogens was chosen as a model system. Signaling circuitry hypotheses in this model system were tested by construction of a differential-equations-based mathematical model. Model-based simulations of time evolution of signaling components matched experimental measurements of programmed cell death and associated signaling components obtained in a companion study. Simulation of systems-level consequences of mutations used in laboratory studies led to two major improvements in understanding of signaling circuitry: (1) Simulations supported experimental evidence that a negative feedback loop in salicylic acid biosynthesis postulated by others does not exist. (2) Simulations showed that a second negative regulatory circuit for which there was strong experimental support did not affect one of two pathways leading to programmed cell death. Simulations also generated testable predictions to guide future experiments. Additional testable hypotheses were generated by results of individually varying each model parameter over 2 orders of magnitude that predicted biologically important changes to system dynamics. These predictions will be tested in future laboratory studies designed to further elucidate the signaling network control structure.

Apoptosis↗

PubMed2005

The flavonoid luteolin prevents lipopolysaccharide-induced NF-kappaB signalling and gene expression by blocking IkappaB kinase activity in intestinal epithelial cells and bone-marrow derived dendritic cells.

The nuclear factor (NF)-kappaB transcriptional system is a major effector pathway involved in inflammation and innate immune responses. The flavonoid luteolin is found in various herbal extracts and has shown anti-inflammatory properties. However, the mechanism of action and impact of luteolin on innate immunity is still unknown. We report that luteolin significantly blocks lipopolysaccharide (LPS)-induced IkappaB phosphorylation/degradation, NF-kappaB transcriptional activity and intercellular adhesion molecule-1 (ICAM-1) gene expression in rat IEC-18 cells. Using chromatin immunoprecipitation, we demonstrate that LPS-induced RelA recruitment to the ICAM-1 gene promoter is significantly reduced in luteolin-treated cells. Moreover, in vitro kinase assays show that luteolin directly inhibits LPS-induced IkappaB kinase (IKK) activity in IEC-18 cells. Using bone-marrow derived dendritic cells (BMDCs) isolated from interleukin (IL)-10(-/-) mice or from recently engineered transgenic mice expressing the enhanced green fluorescent protein (EGFP) under the transcriptional control of NF-kappaB cis-elements (cis-NF-kappaB(EGFP)), we found that luteolin blocks LPS-induced IkappaB phosphorylation and IKK activity, and decreases EGFP, IL-12 and tumour necrosis factor-alpha gene expression. Moreover, intraperitoneal administration of luteolin significantly inhibited LPS-induced EGFP expression in both peripheral blood mononuclear cells and splenocytes isolated from cis-NF-kappaB(EGFP) mice. These results indicate that luteolin blocks LPS-induced NF-kappaB signalling and proinflammatory gene expression in intestinal epithelial cells and dendritic cells. Modulation of innate immunity by natural plant products may represent an attractive strategy to prevent intestinal inflammation associated with dysregulated innate immune responses.

Animals↗

PubMed2026

Balancing growth and immunity of potato by humidity-dependent expression of a late blight resistance gene.

Inducible expression of resistance genes is an effective approach to balance plant growth and immunity, thus facilitating the development of disease-resistant crop cultivars. While pathogen-responsive and immunity-related promoters have been adopted for this purpose, alternative design strategies remain to be explored. High relative humidity (RH) has been recognized as a crucial permissive environmental condition for the occurrence of devastating plant diseases including tomato and potato late blight. Here, we identified humidity-activated cis-regulatory elements (HAEs) in Solanum lycopersicum through an integrative analysis of transcriptomics and chromatin accessibility data. Sequence homology-inferred HAEs in S. tuberosum can predict humidity-elicited changes in downstream gene expression. Transgenic S. tuberosum lines expressing a late blight resistance gene driven by an artificial humidity-inducible promoter containing a natural S. tuberosum HAE were generated. These transgenic lines exhibited comparable late blight resistance levels to the lines overexpressing the same resistance gene in controlled zoospore inoculation bioassays, while avoiding growth suppression and tuber yield penalties in common garden experiments. Our findings highlight the importance of plant cis-regulatory elements in the transcriptional responses to high RH and provide a proof-of-concept for a humidity-inducible environment-responsive resistance gene deployment strategy to engineer disease-resistant crop cultivars without compromising growth and yield.

Phytophthora infestans↗

PubMed1982

Complex studies of the influence of the working conditions in the Plock Petrochemical Plant on the behaviour of some parameters of cell immunity.

Complex evaluations of the function of peripheral blood granulocytes in the Phenol Plant workers were made. Only precise examinations of the bactericidal and ingestive functions as well as the metabolism of those cells may lead to the discovery of a clinically unnoticeable insufficiency of the system as has been confirmed by other authors and by our own previous studies. Routine methods of separating granulocytes of heparinized peripheral blood were used. Phagocytic activity of cells after contact with three antigens was studied. Bactericidal activity of granulocytes in the presence of Staph. aureus and antibactericidal activity of lysosomal proteins of granulocytes were evaluated. According to the general assessment, no permanent disturbances of the granulocyte function were observed in the phenol plant workers. However, disturbances of the phagocytic and bactericidal abilities were detected in some individual cases. In general evaluation no disturbances of function of granulocytes concerning all some cases phagocytary and bactericidal abilities did not occur simultaneously.

Acid Phosphatase↗

PubMed2002

Chloroisonicotinamide derivative induces a broad range of disease resistance in rice and tobacco.

Systemic acquired resistance (SAR) is a potent innate immunity system in plants that is effective against a broad range of pathogens. SAR in dicotyledonous plants such as tobacco and Arabidopsis has been partially elucidated and is mediated by salicylic acid (SA). However, the SAR mechanism of monocotyledonous rice plants remains to be clarified, although some similarities between SAR mechanisms in both types have been reported. Here we have characterized N-cyanomethyl-2-chloroisonicotinamide (NCI) as an effective SAR inducer in both plant species. Soil drench application of NCI induces a broad range of disease resistance in tobacco and rice and, more specifically, PR gene expression in tobacco. Both SA measurements in wild-type NCI-treated tobacco and pathogenic infection studies using NahG transgenic tobacco plants indicate that NCI-induced resistance enhancement does not require SA. Therefore, it is suggested that NCI induces SAR by triggering signaling at the same level as or downstream of SA accumulation as do both benzo(1,2,3)thiadiazole-7-carbothioic acid S-methyl ester and 2,6-dichloroisonicotinic acid. The fact that all of these chemicals are effective in rice and tobacco suggests that several common components function in disease resistance in both plant species.

Bacteria↗

PubMed2000

Changes in cellular immunity among workers occupationally exposed to styrene in a plastics lamination plant.

BACKGROUND: Styrene is a widely used industrial chemical. Immune and hematological parameters were examined in 29 hand laminators and sprayers exposed to styrene for an average of 14 years and in 19 in-factory unexposed controls. The workers performed hand lamination procedures in a production area with an average area airborne styrene level of 139.5 mg/m(3). Mean concentration of styrene in the blood of exposed workers was 945.7 microg/L and the mean styrene in exhaled air was 38.8 microg/L. METHODS: Parameters of internal and external exposure, immune function assays, immunoglobulins, acute phase reactants and hematology were evaluated in exposed and non-exposed populations. RESULTS: Using multifactorial analysis of variance we found a significant decrease in proliferation of lymphocytes stimulated by Concanavalin A but not by pokeweed mitogen (PWM) in workers occupationally exposed to styrene. Proliferative response to PWM was significantly correlated with the levels of styrene in blood. Phagocytic activity of monocytes, levels of IgG, IgA, IgM, IgE and alpha-2-macroglobulin in serum were indistinguishable in the two groups. The population exposed to styrene had increased levels of C4-component of complement. Levels of C3-component of complement were positively correlated with duration of exposure. A significant elevation in the percentage and number of monocytes and a significantly decreased number of lymphocytes were seen in exposed workers. Styrene concentrations in both blood and exhaled air were associated with decreased percentage of large granular lymphocytes. CONCLUSIONS: These results suggest immune alterations of cell-mediated immune response of T-lymphocytes and imbalance in leucocyte subsets in peripheral blood of workers exposed to styrene.

Acute-Phase Proteins↗