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Sample records for nicotiana tabacum defence

  1. Phenylpropanoid Defences in Nicotiana tabacum Cells: Overlapping Metabolomes Indicate Common Aspects to Priming Responses Induced by Lipopolysaccharides, Chitosan and Flagellin-22.

    PubMed

    Mhlongo, Msizi I; Piater, Lizelle A; Madala, Ntakadzeni E; Steenkamp, Paul A; Dubery, Ian A

    2016-01-01

    Plants have evolved both constitutive and inducible defence strategies to cope with different biotic stimuli and stresses. Exposure of a plant to a challenging stress can lead to a primed state that allows it to launch a more rapid and stronger defence. Here we applied a metabolomic approach to study and compare the responses induced in Nicotiana tabacum cells by microbe-associated molecular pattern (MAMP) molecules, namely lipopolysaccharides (LPS), chitosan (CHT) and flagellin-22 (FLG22). Early response metabolites, extracted with methanol, were analysed by UHPLC-MS/MS. Using multivariate statistical tools the metabolic profiles induced by these elicitors were analysed. In the metabolic fingerprint of these agents a total of 19 cinnamic acid derivatives conjugated to quinic acids (chlorogenic acids), shikimic acid, tyramine, polyamines or glucose were found as discriminant biomarkers. In addition, treatment with the phytohormones salicylic acid (SA), methyljasmonic acid (MJ) and abscisic acid (ABA) resulted in differentially-induced phenylpropanoid pathway metabolites. The results indicate that the phenylpropanoid pathway is activated by these elicitors while hydroxycinnamic acid derivatives are commonly associated with the metabolic response to the MAMPs, and that the activated responses are modulated by both SA and MJ, with ABA not playing a role.

  2. Phenylpropanoid Defences in Nicotiana tabacum Cells: Overlapping Metabolomes Indicate Common Aspects to Priming Responses Induced by Lipopolysaccharides, Chitosan and Flagellin-22

    PubMed Central

    Mhlongo, Msizi I.; Piater, Lizelle A.; Madala, Ntakadzeni E.; Steenkamp, Paul A.; Dubery, Ian A.

    2016-01-01

    Plants have evolved both constitutive and inducible defence strategies to cope with different biotic stimuli and stresses. Exposure of a plant to a challenging stress can lead to a primed state that allows it to launch a more rapid and stronger defence. Here we applied a metabolomic approach to study and compare the responses induced in Nicotiana tabacum cells by microbe-associated molecular pattern (MAMP) molecules, namely lipopolysaccharides (LPS), chitosan (CHT) and flagellin-22 (FLG22). Early response metabolites, extracted with methanol, were analysed by UHPLC-MS/MS. Using multivariate statistical tools the metabolic profiles induced by these elicitors were analysed. In the metabolic fingerprint of these agents a total of 19 cinnamic acid derivatives conjugated to quinic acids (chlorogenic acids), shikimic acid, tyramine, polyamines or glucose were found as discriminant biomarkers. In addition, treatment with the phytohormones salicylic acid (SA), methyljasmonic acid (MJ) and abscisic acid (ABA) resulted in differentially-induced phenylpropanoid pathway metabolites. The results indicate that the phenylpropanoid pathway is activated by these elicitors while hydroxycinnamic acid derivatives are commonly associated with the metabolic response to the MAMPs, and that the activated responses are modulated by both SA and MJ, with ABA not playing a role. PMID:26978774

  3. Rapid metabolic profiling of Nicotiana tabacum defence responses against Phytophthora nicotianae using direct infrared laser desorption ionization mass spectrometry and principal component analysis

    PubMed Central

    2010-01-01

    Background Successful defence of tobacco plants against attack from the oomycete Phytophthora nicotianae includes a type of local programmed cell death called the hypersensitive response. Complex and not completely understood signaling processes are required to mediate the development of this defence in the infected tissue. Here, we demonstrate that different families of metabolites can be monitored in small pieces of infected, mechanically-stressed, and healthy tobacco leaves using direct infrared laser desorption ionization orthogonal time-of-flight mass spectrometry. The defence response was monitored for 1 - 9 hours post infection. Results Infrared laser desorption ionization orthogonal time-of-flight mass spectrometry allows rapid and simultaneous detection in both negative and positive ion mode of a wide range of naturally occurring primary and secondary metabolites. An unsupervised principal component analysis was employed to identify correlations between changes in metabolite expression (obtained at different times and sample treatment conditions) and the overall defence response. A one-dimensional projection of the principal components 1 and 2 obtained from positive ion mode spectra was used to generate a Biological Response Index (BRI). The BRI obtained for each sample treatment was compared with the number of dead cells found in the respective tissue. The high correlation between these two values suggested that the BRI provides a rapid assessment of the plant response against the pathogen infection. Evaluation of the loading plots of the principal components (1 and 2) reveals a correlation among three metabolic cascades and the defence response generated in infected leaves. Analysis of selected phytohormones by liquid chromatography electrospray ionization mass spectrometry verified our findings. Conclusion The described methodology allows for rapid assessment of infection-specific changes in the plant metabolism, in particular of phenolics, alkaloids

  4. Silicon delays tobacco Ringspot virus systemic symptoms in Nicotiana tabacum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soluble silicon (Si) provides protection to plants against a variety of abiotic and biotic stress. However, the role of Si in viral infections has been elusive. To investigate the role of Si in viral infections, hydroponic studies were conducted in Nicotiana tabacum with two pathogens: Tobacco rings...

  5. Streptomycin resistant and sensitive somatic hybrids of Nicotiana tabacum + Nicotiana knightiana: correlation of resistance to N. tabacum plastids.

    PubMed

    Menczel, L; Nagy, F; Kiss, Z R; Maliga, P

    1981-03-01

    Protoplasts of Nicotiana tabacum SRI (streptomycin resistant) and of Nicotiana knightiana (streptomycin sensitive) were fused using polyethylene glycol treatment. From three heterokaryons 500 clones were obtained. From the 43 which were further investigated, 6 resistant, 3 sensitive, and 34 chimeric (consisting of resistant and sensitive sectors) calli were found. From eight clones, a total of 39 plants were regenerated and identified as somatic hybrids. Chloroplast type (N. tabacum = NT or N. knightiana = NK) in the plants was determined on the basis of the species specific EcoRI restriction pattern of the chloroplast DNA. Regenerates contained NT (13 plants) or NK (15 plants) plastids but only the plants with the NT chloroplasts were resistant to streptomycin. This finding and our earlier data on uniparental inheritance points to the chloroplasts as the carriers of the streptomycin resistance factor.

  6. Metabolomic analysis of isonitrosoacetophenone-induced perturbations in phenolic metabolism of Nicotiana tabacum cells.

    PubMed

    Madala, Ntakadzeni E; Steenkamp, Paul A; Piater, Lizelle A; Dubery, Ian A

    2013-10-01

    Plants have developed biochemical and molecular responses to adapt to different stress environments. One of the characteristics of the multi-component defence response is the production of defence-related metabolites. Plant defences can be triggered by various stimuli, including synthetic or naturally occurring molecules, especially those derived from pathogens. In the current study, Nicotiana tabacum cell suspensions were treated with isonitrosoacetophenone (INAP), a subcomponent of a plant-derived stress metabolite with anti-fungal and anti-oxidant properties, in order to investigate the effect thereof on cellular metabolism. Subsequent metabolomic-based analyses were employed to evaluate changes in the metabolome. UPLC-MS in conjunction with multivariate data analyses was found to be an appropriate approach to study the effect of chemical inducers like INAP on plant metabolism in this model system. Principal component analysis (PCA) indicated that INAP is capable of inducing time-dependent metabolic perturbations in the cultured cells. Orthogonal projection to latent structures discriminant analysis (OPLS-DA) revealed metabolites of which the levels are affected by INAP, and eight of these were tentatively annotated from the mass spectral data and online databases. These metabolites are known in the context of plant stress- and defence responses and include benzoic- or cinnamic acid derivatives that are either glycosylated or quinilated as well as flavonoid derivatives. The results indicate that INAP affects the shikimate-, phenylpropanoid- and flavonoid pathways, the products of which may subsequently lead to an anti-oxidant environment in vivo.

  7. Pollination triggers female gametophyte development in immature Nicotiana tabacum flowers

    PubMed Central

    Brito, Michael S.; Bertolino, Lígia T.; Cossalter, Viviane; Quiapim, Andréa C.; DePaoli, Henrique C.; Goldman, Gustavo H.; Teixeira, Simone P.; Goldman, Maria H. S.

    2015-01-01

    In Nicotiana tabacum, female gametophytes are not fully developed at anthesis, but flower buds pollinated 12 h before anthesis produce mature embryo sacs. We investigated several pollination-associated parameters in N. tabacum flower buds to determine the developmental timing of important events in preparation for successful fertilization. First, we performed hand pollinations in flowers from stages 4 to 11 to study at which developmental stage pollination would produce fruits. A Peroxtesmo test was performed to correlate peroxidase activity on the stigma surface, indicative of stigma receptivity, with fruit set. Pollen tube growth and female gametophyte development were microscopically analyzed in pistils of different developmental stages. Fruits were obtained only after pollinations of flower buds at late stage 7 and older; fruit weight and seed germination capacity increased as the developmental stage of the pollinated flower approached anthesis. Despite positive peroxidase activity and pollen tube growth, pistils at stages 5 and 6 were unable to produce fruits. At late stage 7, female gametophytes were undergoing first mitotic division. After 24 h, female gametophytes of unpollinated pistils were still in the end of the first division, whereas those of pollinated pistils showed egg cells. RT-qPCR assay showed that the expression of the NtEC1 gene, a marker of egg cell development, is considerably higher in pollinated late stage 7 ovaries compared with unpollinated ovaries. To test whether ethylene is the signal eliciting female gametophyte maturation, the expression of ACC synthase was examined in unpollinated and pollinated stage 6 and late stage 7 stigmas/styles. Pollination induced NtACS expression in stage 6 pistils, which are unable to produce fruits. Our results show that pollination is a stimulus capable of triggering female gametophyte development in immature tobacco flowers and suggests the existence of a yet undefined signal sensed by the pistil. PMID

  8. Pathway of phloem unloading in tobacco sink leaves. [Nicotiana tabacum

    SciTech Connect

    Turgeon, R.

    1987-04-01

    Phloem unloading in transition sink leaves of tobacco (Nicotiana tabacum L.) was analyzed by quantitative autoradiography. Source leaves were labeled with /sup 14/CO/sub 2/ and experimental treatments were begun approximately 1 h later when label had entered the sink leaves. Autoradiographs were prepared from rapidly frozen, lyophilized sink tissue at the beginning and end of the treatments and the amount of label in veins and in surrounding cells was determined by microdensitometry. Photoassimilate unloaded from third order and larger, but not smaller, veins. Long-distance import and unloading did not respond the same way to all experimental treatments. Import was completely inhibited by cold, anaerobiosis or steam girdling the sink leaf petiole. Unloading was inhibited by cold but continued in an anaerobic atmosphere and after steam girdling. Uptake of exogenous (/sup 14/C)sucrose was inhibited by anaerobiosis. Since an apoplastic pathway of phloem unloading would involve solute uptake from the apoplast the results are most consistent with passive symplastic unloading of photoassimilates from phloem to surrounding cells.

  9. CRISPR/Cas9-mediated targeted mutagenesis in Nicotiana tabacum.

    PubMed

    Gao, Junping; Wang, Genhong; Ma, Sanyuan; Xie, Xiaodong; Wu, Xiangwei; Zhang, Xingtan; Wu, Yuqian; Zhao, Ping; Xia, Qingyou

    2015-01-01

    Genome editing is one of the most powerful tools for revealing gene function and improving crop plants. Recently, RNA-guided genome editing using the type II clustered regularly interspaced short palindromic repeats (CRISPR)-associated protein (Cas) system has been used as a powerful and efficient tool for genome editing in various organisms. Here, we report genome editing in tobacco (Nicotiana tabacum) mediated by the CRISPR/Cas9 system. Two genes, NtPDS and NtPDR6, were used for targeted mutagenesis. First, we examined the transient genome editing activity of this system in tobacco protoplasts, insertion and deletion (indel) mutations were observed with frequencies of 16.2-20.3% after transfecting guide RNA (gRNA) and the nuclease Cas9 in tobacco protoplasts. The two genes were also mutated using multiplexing gRNA at a time. Additionally, targeted deletions and inversions of a 1.8-kb fragment between two target sites in the NtPDS locus were demonstrated, while indel mutations were also detected at both the sites. Second, we obtained transgenic tobacco plants with NtPDS and NtPDR6 mutations induced by Cas9/gRNA. The mutation percentage was 81.8% for NtPDS gRNA4 and 87.5% for NtPDR6 gRNA2. Obvious phenotypes were observed, etiolated leaves for the psd mutant and more branches for the pdr6 mutant, indicating that highly efficient biallelic mutations occurred in both transgenic lines. No significant off-target mutations were obtained. Our results show that the CRISPR/Cas9 system is a useful tool for targeted mutagenesis of the tobacco genome.

  10. Molecular genetics of alkaloid biosynthesis in Nicotiana tabacum.

    PubMed

    Dewey, Ralph E; Xie, Jiahua

    2013-10-01

    Alkaloids represent an extensive group of nitrogen-containing secondary metabolites that are widely distributed throughout the plant kingdom. The pyridine alkaloids of tobacco (Nicotiana tabacum L.) have been the subject of particularly intensive investigation, driven largely due to the widespread use of tobacco products by society and the role that nicotine (16) (see Fig. 1) plays as the primary compound responsible for making the consumption of these products both pleasurable and addictive. In a typical commercial tobacco plant, nicotine (16) comprises about 90% of the total alkaloid pool, with the alkaloids nornicotine (17) (a demethylated derivative of nicotine), anatabine (15) and anabasine (5) making up most of the remainder. Advances in molecular biology have led to the characterization of the majority of the genes encoding the enzymes directly responsible the biosynthesis of nicotine (16) and nornicotine (17), while notable gaps remain within the anatabine (15) and anabasine (5) biosynthetic pathways. Several of the genes involved in the transcriptional regulation and transport of nicotine (16) have also been elucidated. Investigations of the molecular genetics of tobacco alkaloids have not only provided plant biologists with insights into the mechanisms underlying the synthesis and accumulation of this important class of plant alkaloids, they have also yielded tools and strategies for modifying the tobacco alkaloid composition in a manner that can result in changing the levels of nicotine (16) within the leaf, or reducing the levels of a potent carcinogenic tobacco-specific nitrosamine (TSNA). This review summarizes recent advances in our understanding of the molecular genetics of alkaloid biosynthesis in tobacco, and discusses the potential for applying information accrued from these studies toward efforts designed to help mitigate some of the negative health consequences associated with the use of tobacco products.

  11. Production, partial purification and characterization of xylanase using Nicotiana tabacum leaf dust as substrate.

    PubMed

    Acharya, Komal P; Shilpkar, Prateek

    2016-03-01

    Isolated Bacillus sp. was used in the present study for production of xylanase from Nicotiana tabacum leaf dust. The strain was able to give a maximum of 1.77 Uml⁻¹ xylanase activity under optimized fermentation conditions which was further increased upto 2.77 Uml⁻¹ after extraction and partial purification of enzyme. After partial purification, the enzyme was characterized and it gave the highest xylanase activity at pH 7.0, when 0.2 ml enzyme was incubated with 2.0% substrate (Nicotiana tabacum leaf dust) for 60 min at 60°C. Saccharification study of Nicotiana tabacum leaf dust with partially purified enzyme revealed that 18.4% reducing sugar was released in 20 hrs incubation, and TLC and HPTLC analysis showed that xylose and glucose sugars were obtained after hydrolysis of substrate. FTIR analysis confirmed decomposition of substrate.

  12. Nicotiana tabacum as model for ozone - plant surface reactions

    NASA Astrophysics Data System (ADS)

    Jud, Werner; Fischer, Lukas; Wohlfahrt, Georg; Tissier, Alain; Canaval, Eva; Hansel, Armin

    2015-04-01

    Elevated tropospheric ozone concentrations are considered a toxic threat to plants, responsible for global crop losses with associated economic costs of several billion dollars per year. The ensuing injuries have been related to the uptake of ozone through the stomatal pores and oxidative effects damaging the internal leaf tissue. A striking question of current research is the environment and plant specific partitioning of ozone loss between gas phase, stomatal or plant surface sink terms. Here we show results from ozone fumigation experiments using various Nicotiana Tabacum varieties, whose surfaces are covered with different amounts of unsaturated diterpenoids exuded by their glandular trichomes. Exposure to elevated ozone levels (50 to 150 ppbv) for 5 to 15 hours in an exceptionally clean cuvette system did neither result in a reduction of photosynthesis nor caused any visible leaf damage. Both these ozone induced stress effects have been observed previously in ozone fumigation experiments with the ozone sensitive tobacco line Bel-W3. In our case ozone fumigation was accompanied by a continuous release of oxygenated volatile organic compounds, which could be clearly associated to their condensed phase precursors for the first time. Gas phase reactions of ozone were avoided by choosing a high enough gas exchange rate of the plant cuvette system. In the case of the Ambalema variety, that is known to exude only the diterpenoid cis-abienol, ozone fumigation experiments yield the volatiles formaldehyde and methyl vinyl ketone (MVK). The latter could be unequivocally separated from isomeric methacrolein (MACR) by the aid of a Selective Reagent Ion Time-of-Flight Mass Spectrometer (SRI-ToF-MS), which was switched every six minutes from H3O+ to NO+ primary ion mode and vice versa. Consistent with the picture of an ozone protection mechanism caused by reactive diterpenoids at the leaf surface are the results from dark-light experiments. The ozone loss obtained from the

  13. Cloning and Expression of TNF Related Apoptosis Inducing Ligand in Nicotiana tabacum

    PubMed Central

    Heidari, Hamid Reza; Bandehpour, Mojgan; Vahidi, Hossein; Barar, Jaleh; Kazemi, Bahram; Naderi-Manesh, Hossein

    2015-01-01

    Molecular farming has been considered as a secure and economical approach for production of biopharmaceuticals. Human TNF Related Apoptosis Inducing Ligand (TRAIL) as a promising biopharmaceutical candidate has been produced in different expression hosts. However, little attention has been paid to molecular farming of the TRAIL in spite of numerous advantages of plant expression systems. Therefore, in this study the cytoplasmic production of the TRAIL was tackled in Nicotiana tabacum using Agrobacterium tumefaciens LBA 4404. Initially, the desired coding sequence was obtained using PCR technique on the constructed human cDNA library. Afterward, the necessary requirements for expression of the TRAIL in plant cell system were provided through sub-cloning into 35S-CaMV (Cauliflower Mosaic Virus) helper and final 0179-pGreen expression vectors. Then, the final TRAIL-pGreen expression vector was cloned into A. tumefaciens LBA 4404. Subsequently, the N. tabacum cells were transformed through co-culture method and expression of the TRAIL was confirmed by western blot analysis. Finally, the recombinant TRAIL was extracted through chromatographic technique and biological activity was evaluated through MTT assay (Methylthiazol Tetrazolium Assay). The result of western blot analysis indicated that only monomer and oxidized dimer forms of the TRAIL can be extracted from the N. tabacum cells. Moreover, the lack of trimeric assembly of the extracted TRAIL diminished its biological activity in sensitive A549 cell line. In conclusion, although N. tabacum cells can successfully produce the TRAIL, proper assembly and functionality of the TRAIL were unfavorable. PMID:25561925

  14. Short-term effects of hydrogen fluoride on Nicotiana tabacum L.

    PubMed

    Döğeroğlu, Tuncay; Ciçek, Arzu; Kara, Serap

    2003-09-01

    Data on the short-term effects of fumigation with hydrogen fluoride (HF) on the response behavior of the Nicotiana tabacum L. cv. St. Karabalar 6265 are being presented. Growth rate, fluoride accumulation in leaves and soils, and degradation in chlorophyll and nicotine contents of the plant species against the variations in two experimental factors, namely the exposure concentration and exposure time parameters, were investigated. Resulting data reveals that the variety selected for this study is not so tolerant to fluoride as generally reported in the literature, if only the individual effects of the pollutant is considered.

  15. Influence of selected herbicides on ozone injury in tobacco (Nicotiana tabacum)

    SciTech Connect

    Reilly, J.J.; Moore, L.D.

    1982-01-01

    Field experiments were conducted over a four year period to determine the influence of selected herbicides on ozone injury in tobacco (Nicotiana tabacum L.). Isopropalin (2,6-dinitro-N,N-dipropylcumidine), pebulate (S-propyl butylethylthiocarbamate), and diphenamid (N,N-dimethyl-2,2-diphenylacetamide) were applied at the recommended rates of 1.7, 4.5, and 4.5 kg/ha (ai), respectively. Treatment of tobacco plants with isopropalin or diphenamid reduced oxidant injury for the first two to four weeks after transplanting, but not later in the season. Pebulate has no consistent affect on the sensitivity of tobacco to ozone. 26 references, 3 tables.

  16. Heat shock, with recovery, promotes protection of Nicotiana tabacum during subsequent exposure to Ralstonia solanacearum.

    PubMed

    Byth-Illing, Heather-Anne; Bornman, Liza

    2014-03-01

    Host-pathogen interactions in plants are complex and potentially influenced by heat shock/stress (HS). Host HS proteins (HSPs) induced prior to bacterial exposure may facilitate the folding of newly synthesized defense proteins and promote incompatible host-pathogen interactions. We hypothesized that a non-lethal HS, with recovery, promotes protection of Nicotiana tabacum during subsequent exposure to avirulent soilborne necrotrophic pathogen Ralstonia solanacearum. The objective of this study included investigating the effects of HS with or without recovery on the outcome of bacterial exposure to a virulent and avirulent biovar of R. solanacearum in N. tabacum cell suspensions. This was assessed by quantifying host Hsp70/Hsc70 levels, mitochondrial electron (e (-)) transport activity as a marker of viability, and phosphatidylserine externalization and DNA fragmentation as markers of apoptosis. Our findings support the hypothesis that HS, with recovery, promotes protection of N. tabacum during subsequent exposure to R. solanacearum, suggesting a role for Hsp70/Hsc70 in the observed protection of e (-) transport, increased apoptosis, and DNA fragmentation.

  17. RNA-dependent RNA polymerase 1 from Nicotiana tabacum suppresses RNA silencing and enhances viral infection in Nicotiana benthamiana.

    PubMed

    Ying, Xiao-Bao; Dong, Li; Zhu, Hui; Duan, Cheng-Guo; Du, Quan-Sheng; Lv, Dian-Qiu; Fang, Yuan-Yuan; Garcia, Juan Antonio; Fang, Rong-Xiang; Guo, Hui-Shan

    2010-04-01

    Endogenous eukaryotic RNA-dependent RNA polymerases (RDRs) produce double-stranded RNA intermediates in diverse processes of small RNA synthesis in RNA silencing pathways. RDR6 is required in plants for posttranscriptional gene silencing induced by sense transgenes (S-PTGS) and has an important role in amplification of antiviral silencing. Whereas RDR1 is also involved in antiviral defense in plants, this does not necessarily proceed through triggering silencing. In this study, we show that Nicotiana benthamiana transformed with RDR1 from Nicotiana tabacum (Nt-RDR1 plants) exhibits hypersusceptibility to Plum pox potyvirus and other viruses, resembling RDR6-silenced (RDR6i) N. benthamiana. Analysis of transient induction of RNA silencing in N. benthamiana Nt-RDR1 and RDR6i plants revealed that Nt-RDR1 possesses silencing suppression activity. We found that Nt-RDR1 does not interfere with RDR6-dependent siRNA accumulation but turns out to suppress RDR6-dependent S-PTGS. Our results, together with previously published data, suggest that RDR1 might have a dual role, contributing, on one hand, to salicylic acid-mediated antiviral defense, and suppressing, on the other hand, the RDR6-mediated antiviral RNA silencing. We propose a scenario in which the natural loss-of-function variant of RDR1 in N. benthamiana may be the outcome of selective pressure to maintain a high RDR6-dependent antiviral defense, which would be required to face the hypersensitivity of this plant to a large number of viruses.

  18. Early events induced by the toxin deoxynivalenol lead to programmed cell death in Nicotiana tabacum cells.

    PubMed

    Yekkour, Amine; Tran, Daniel; Arbelet-Bonnin, Delphine; Briand, Joël; Mathieu, Florence; Lebrihi, Ahmed; Errakhi, Rafik; Sabaou, Nasserdine; Bouteau, François

    2015-09-01

    Deoxynivalenol (DON) is a mycotoxin affecting animals and plants. This toxin synthesized by Fusarium culmorum and Fusarium graminearum is currently believed to play a decisive role in the fungal phytopathogenesis as a virulence factor. Using cultured cells of Nicotiana tabacum BY2, we showed that DON-induced programmed cell death (PCD) could require transcription and translation processes, in contrast to what was observed in animal cells. DON could induce different cross-linked pathways involving (i) reactive oxygen species (ROS) generation linked, at least partly, to a mitochondrial dysfunction and a transcriptional down-regulation of the alternative oxidase (Aox1) gene and (ii) regulation of ion channel activities participating in cell shrinkage, to achieve PCD.

  19. A novel pollen tube growth assay utilizing a transmitting tract-ablated Nicotiana tabacum style.

    PubMed

    Eberle, Carrie A; Clasen, Benjamin M; Anderson, Neil O; Smith, Alan G

    2012-03-01

    Sexual plant reproduction requires multiple pollen-pistil interactions from the stigma (pollen adhesion, hydration, and germination) to the ovary (fertilization). Understanding the factors that regulate pollen tube growth is critical to understanding the processes essential to sexual reproduction. Many pollen tube growth assays (PTGAs) have shorter and slower pollen tube growth when compared to pollen tube growth through the style. The identification and study of factors that regulate pollen tube growth have been impeded by a lack of an efficient and reproducible PTGA. The objective of this research is to develop a robust assay for Nicotiana tabacum pollen tube growth in an environment that supports sustained and normal growth yet is amenable to testing the effects of specific factors. In this paper, we introduce a novel PTGA, which uses pistils from N. tabacum that lack a mature transmitting tract (TT) due to tissue-specific ablation. The TT-ablated style supports normal pollen tube growth and the hollow structure of the style allows modification of the growth environment by direct injection of test material. This PTGA is robust and allows for rapid and accurate measurement of pollen tube length and pollen tube morphology, supporting pollen tube growth from 20 to 35°C and at pH ranging from 4.8 to 7.6. Use of the ablated style for a PTGA is a novel method for the culture of pollen tubes with sustained growth in vivo while permitting the application of treatments to the growing pollen tubes.

  20. [Induction of polyploid in hairy roots of Nicotiana tabacum and its plant regeneration].

    PubMed

    Hou, Lili; Shi, Heping; Yu, Wu; Tsang, Po Keung Eric; Chow, Cheuk Fai Stephen

    2014-04-01

    By genetic transformation with Agrobacterum rhizogenes and artificial chromosome doubling techniques, we studied the induction of hairy roots and their polyploidization, and subsequent plant regeneration and nicotine determination to enhance the content of nicotine in Nicotiana tabacum. The results show that hairy roots could be induced from the basal surface of leaf explants of N. tabacum 8 days after inoculation with Agrobacterium rhizogenes ATCC15834. The percentage of the rooting leaf explants was 100% 15 days after inoculation. The hairy roots could grow rapidly and autonomously on solid or liquid phytohormones-free MS medium. The transformation was confirmed by PCR amplification of rol gene of Ri plasmid and paper electrophoresis of opines from N. tabacum hairy roots. The highest rate of polyploidy induction, more than 64.71%, was obtained after treatment of hairy roots with 0.1% colchicine for 36 h. The optimum medium for plant regeneration from polyploid hairy roots was MS+2.0 mg/L 6-BA +0.2 mg/L NAA. Compared with the control diploid plants, the hairy roots-regenerated plants had weak apical dominance, more axillary buds and more narrow leaves; whereas the polyploid hairy root-regenerated plants had thicker stems, shorter internodes and the colour, width and thickness of leaves were significantly higher than that of the control. Observation of the number of chromosomes in their root tip cells reveals that the obtained polyploid regenerated plants were tetraploidy, with 96 (4n = 96) chromosomes. Pot-grown experiments showed compared to the control, the flowering was delayed by 21 days in diploid hairy roots-regenerated plants and polyploid hairy root-regenerated plants. GC-MS detection shows that the content of nicotine in polyploid plants was about 6.90 and 4.57 times the control and the diploid hairy roots-regenerated plants, respectively.

  1. Expression of a Self-Incompatibility Glycoprotein (S2-Ribonuclease) from Nicotiana alata in Transgenic Nicotiana tabacum.

    PubMed Central

    Murfett, J; Cornish, EC; Ebert, PR; Bonig, I; McClure, BA; Clarke, AE

    1992-01-01

    In Nicotiana alata, self-incompatibility is controlled by a single locus, designated the S-locus, with multiple alleles. Stylar products of these alleles are ribonucleases that are secreted mainly in the transmitting tract tissues. N. tabacum plants were transformed with constructs containing the S2-cDNA and genomic S2-sequences from N. alata that were linked to the cauliflower mosaic virus 35S promoter. Unlike other genes controlled by this promoter, the genes were expressed most highly in mature floral organs. This pattern of expression was observed at both the protein and RNA levels. The S2-glycoprotein was detected in the stylar transmitting tract tissues of the transgenic plants. The transgene product was secreted, had ribonuclease activity, and was glycosylated with the correct number of glycan chains. However, the maximum level of S2-glycoprotein in styles of the transgenic plants was approximately 100-fold lower than that found in N. alata styles carrying the S2-allele. Perhaps because of this lower protein level, the plants showed no changes in the incompatibility phenotype. PMID:12297668

  2. Expression of synthetic human tropoelastin (hTE) protein in Nicotiana tabacum

    PubMed Central

    Abdelghani, Mona; El-Heba, Ghada A Abu; Abdelhadi, Abdelhadi A; Abdallah, Naglaa A

    2015-01-01

    ABSTRACT Plant molecular farming (PMF) is an important growing prospective approach in plant biotechnology; it includes production of recombinant pharmaceutical and industrial proteins in large quantities from engineered plants. Elastin is a major protein component of tissues that require elasticity, it helps keep skin smooth as it stretches to allow normal.  Elastin is used as a raw material for the cosmetic industry. In this work, we aimed to use plant as a bioreactor for the expression and production of the full human tropoelastin protein. Agrobacterium- mediated transient expression system into Nicotiana tabacum using syringe agroinfiltration was used to provide fast and convenient way to produce recombinant proteins with greater expression overall the plant leaf. This study aimed to establish an efficient and rapid system for transiently expression and production of human recombinant tropoelastin protein in transgenic N. tabacum plants. Modified elastin (ELN) gene was biosynthesized and cloned into pCambia1390 vector to be used into N. tabacum agroinfilteration. Optimization of codon usage for the human tropoelastin gene, without changing the primary structure of the protein was carried out to ensure high expression in tobacco plants. The obtained data proved that the 5th day post-infiltration is the optimum interval to obtain the maximum production of our recombinant protein. Southern blot analysis was able to detect 2175 bp fragment length representing the ELN orf (open reding frame). On the other hand, ELN -expression within plant's tissue was visualized by RT-PCR during the period 3–10 days post agroinfiltration. At the protein level, western and ELISA confirmed the expression of recombinant tropoelastin protein. Western blot analysis detected the tropoelastin protein as parent band at ∼70 kDa from freshly extracted protein, while two degraded bands of ∼55 and ∼45 kDa, representing a pattern of tropoelastin were appeared with frozen samples

  3. Phytoaccumulation of lead by sunflower (Helianthus annuus), tobacco (Nicotiana tabacum), and vetiver (Vetiveria zizanioides).

    PubMed

    Boonyapookana, Benjaporn; Parkpian, Preeda; Techapinyawat, Sombun; DeLaune, R D; Jugsujinda, Aroon

    2005-01-01

    The ability of three plant species: Helianthus annuus, Nicotiana tabacum, and Vetiveria zizanioides for phytoaccumulation of Pb was studied. Plants were grown in hydroponic solution containing Pb(NO3)2 at concentration of 0.25 and 2.5 mM Pb in the presence or absence of chelating agents (EDTA or DTPA). Lead (Pb) transport and localization within the tissues of the plant species was determined using scanning electron microscope equipped with energy dispersive X-ray spectrometers (SEM-EDS). The addition of chelators increased Pb uptake as compared to plants grown in solution containing Pb alone. Lead taken up by the plant species were concentrated in both leaf and stem at the region of vascular bundles with greater amounts in the leaf portion. Lead granules were also found in the H. annuus root tissue from the epidermis layer to the central axis. After four weeks of growth a 23-fold increase in shoot Pb content for H. annuus and N. tabacum and 17-fold increase in shoot Pb for V. zizanioides resulted from plants grown in the 2.5 mM Pb-EDTA treatment. The higher Pb treatment (2.5 mM Pb containing EDTA) resulted in higher concentrations of Pb in plant tissue at the fourth week of exposure as compared to Pb treatment containing DTPA. Overall, Pb accumulation potential of H. annuus was greater than that of N. tabacum and V. zizanioides as indicated by the bioconcentration factor (171, 70, and 88, respectively). The highest measured Pb concentrations were found in H. annuus roots, stems, and leaves (2668, 843, and 3611 microg/g DW, respectively) grown in the 2.5 mM Pb-EDTA treatment. The addition of chelators caused some reduction in plant growth and biomass. Results showed that the three plant species tested have potential for use in phytoaccumulation of Pb since the Pb was concentrated in leaf and stem as compared to control plants. H. annuus however best meet the prerequisites for a hyperaccumulator plant and would have the potential for use in the restoration of

  4. Larval Helicoverpa zea Transcriptional, Growth and Behavioral Responses to Nicotine and Nicotiana tabacum

    PubMed Central

    Gog, Linus; Vogel, Heiko; Hum-Musser, Sue M.; Tuter, Jason; Musser, Richard O.

    2014-01-01

    The polyphagous feeding habits of the corn earworm, Helicoverpa zea (Boddie), underscore its status as a major agricultural pest with a wide geographic distribution and host plant repertoire. To study the transcriptomic response to toxins in diet, we conducted a microarray analysis of H. zea caterpillars feeding on artificial diet, diet laced with nicotine and Nicotiana tabacum (L.) plants. We supplemented our analysis with growth and aversion bioassays. The transcriptome reflects an abundant expression of proteases, chitin, cytochrome P450 and immune-related genes, many of which are shared between the two experimental treatments. However, the tobacco treatment tended to elicit stronger transcriptional responses than nicotine-laced diet. The salivary factor glucose oxidase, known to suppress nicotine induction in the plant, was upregulated by H. zea in response to tobacco but not to nicotine-laced diet. Reduced caterpillar growth rates accompanied the broad regulation of genes associated with growth, such as juvenile hormone epoxide hydrolase. The differential expression of chemosensory proteins, such as odorant binding-protein-2 precursor, as well as the neurotransmitter nicotinic-acetylcholine-receptor subunit 9, highlights candidate genes regulating aversive behavior towards nicotine. We suggest that an observed coincidental rise in cannibalistic behavior and regulation of proteases and protease inhibitors in H. zea larvae signify a compensatory response to induced plant defenses. PMID:26462833

  5. Mitochondrial alternative oxidase maintains respiration and preserves photosynthetic capacity during moderate drought in Nicotiana tabacum.

    PubMed

    Dahal, Keshav; Wang, Jia; Martyn, Greg D; Rahimy, Farkhunda; Vanlerberghe, Greg C

    2014-11-01

    The mitochondrial electron transport chain includes an alternative oxidase (AOX) that is hypothesized to aid photosynthetic metabolism, perhaps by acting as an additional electron sink for photogenerated reductant or by dampening the generation of reactive oxygen species. Gas exchange, chlorophyll fluorescence, photosystem I (PSI) absorbance, and biochemical and protein analyses were used to compare respiration and photosynthesis of Nicotiana tabacum 'Petit Havana SR1' wild-type plants with that of transgenic AOX knockdown (RNA interference) and overexpression lines, under both well-watered and moderate drought-stressed conditions. During drought, AOX knockdown lines displayed a lower rate of respiration in the light than the wild type, as confirmed by two independent methods. Furthermore, CO2 and light response curves indicated a nonstomatal limitation of photosynthesis in the knockdowns during drought, relative to the wild type. Also relative to the wild type, the knockdowns under drought maintained PSI and PSII in a more reduced redox state, showed greater regulated nonphotochemical energy quenching by PSII, and displayed a higher relative rate of cyclic electron transport around PSI. The origin of these differences may lie in the chloroplast ATP synthase amount, which declined dramatically in the knockdowns in response to drought. None of these effects were seen in plants overexpressing AOX. The results show that AOX is necessary to maintain mitochondrial respiration during moderate drought. In its absence, respiration rate slows and the lack of this electron sink feeds back on the photosynthetic apparatus, resulting in a loss of chloroplast ATP synthase that then limits photosynthetic capacity.

  6. Isoprene emission protects photosynthesis but reduces plant productivity during drought in transgenic tobacco (Nicotiana tabacum) plants.

    PubMed

    Ryan, Annette C; Hewitt, C Nicholas; Possell, Malcolm; Vickers, Claudia E; Purnell, Anna; Mullineaux, Philip M; Davies, William J; Dodd, Ian C

    2014-01-01

    Isoprene protects the photosynthetic apparatus of isoprene-emitting plants from oxidative stress. The role of isoprene in the response of plants to drought is less clear. Water was withheld from transgenic isoprene-emitting and non-emitting tobacco (Nicotiana tabacum) plants, to examine: the response of isoprene emission to plant water deficit; a possible relationship between concentrations of the drought-induced phytohormone abscisic acid (ABA) and isoprene; and whether isoprene affected foliar reactive oxygen species (ROS) and lipid peroxidation levels. Isoprene emission did not affect whole-plant water use, foliar ABA concentration or leaf water potential under water deficit. Compared with well-watered controls, droughted non-emitting plants significantly increased ROS content (31-46%) and lipid peroxidation (30-47%), concomitant with decreased operating and maximum efficiencies of photosystem II photochemistry and lower leaf and whole-plant water use efficiency (WUE). Droughted isoprene-emitting plants showed no increase in ROS content or lipid peroxidation relative to well-watered controls, despite isoprene emission decreasing before leaf wilting. Although isoprene emission protected the photosynthetic apparatus and enhanced leaf and whole-plant WUE, non-emitting plants had 8-24% more biomass under drought, implying that isoprene emission incurred a yield penalty.

  7. Integration and expression of a rabbit liver cytochrome P-450 gene in transgenic Nicotiana tabacum.

    PubMed Central

    Saito, K; Noji, M; Ohmori, S; Imai, Y; Murakoshi, I

    1991-01-01

    Cytochrome P-450 is involved in the oxidative metabolism of a broad range of substrates. We have made a chimeric construct, pSN002, containing the cDNA for rabbit liver cytochrome P-450 (IIC14) under the control of the TR2' promoter for mannopine synthase in the Agrobacterium Ti plasmid. Nicotiana tabacum was transformed with Agrobacterium tumefaciens harboring a cointegrated plasmid pSN002::pGV2260. The presence of mRNA and of the translated protein from the chimeric cytochrome P-450 gene in transgenic plants was confirmed by RNA blot hybridization and by Western blot and immunohistochemical analyses, respectively. The transformants in which the foreign cytochrome P-450 protein is expressed show marked phenotypic changes, notably a tendency rapidly to senesce. We detected 2-propenylpyrrolidine, a degradative metabolite of nicotine alkaloids, in transgenic tobacco showing this pronounced phenotypic change. Such metabolism is likely to be due to the effect of senescence and not directly to the presence of the cytochrome P-450. Images PMID:1714583

  8. Crystalline ribulose bisphosphate carboxylase/oxygenase of high integrity and catalytic activity from Nicotiana tabacum.

    PubMed

    Servaites, J C

    1985-04-01

    Crystalline tobacco (Nicotiana tabacum L.) ribulose-1,5-bisphosphate carboxylase/oxygenase (EC 4.1.1.39) was prepared using a procedure which protected the enzyme from hydrolysis by endogenous proteases. Leaves were extracted in a buffered medium containing casein, leupeptin, and high concentrations of MgSO4 and NaHCO3. After filtration through ion-exchange resin to remove contaminants, the enzyme was concentrated by precipitation with polyethylene glycol and crystal formation was induced by low-salt dialysis. The crystalline enzyme had a measured specific activity of 1.7 mumol CO2 mg protein-1 min-1, and about 93% of the enzyme could be activated with Mg2+ and CO2. Crystalline enzyme prepared in the absence of casein exhibited an activity which was only one-third of this rate and only about 70% of the enzyme could be activated with Mg2+ and CO2. Casein-extracted enzyme was resolved into distinct bands corresponding to the large (55,000) and small (14,000) subunits by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The large subunit of enzyme prepared according to the latter procedure was found to be composed of five different polypeptides of slightly decreasing molecular weight. Only about one-third of the large subunits were of the 55,000 molecular weight type. No differences between the two preparations were observed in the Km (CO2) and apparent Km (ribulose bisphosphate).

  9. Lysinibacillus tabacifolii sp. nov., a novel endophytic bacterium isolated from Nicotiana tabacum leaves.

    PubMed

    Duan, Yan-Qing; He, Song-Tao; Li, Qing-Qing; Wang, Ming-Feng; Wang, Wen-Yuan; Zhe, Wei; Cao, Yong-Hong; Mo, Ming-He; Zhai, Yu-Long; Li, Wen-Jun

    2013-06-01

    A Gram-positive, catalase- and oxidase-positive, strictly aerobic, endospore-forming rod bacterium, designated K3514(T), was isolated from the leaves of Nicotiana tabacum. The strain was able to grow at temperatures of 8-40°C, pH 5.0-10.0 and NaCl concentrations of 0-7%. The predominant quinones (>30%) of this strain were MK-7(H2) and MK-7. Phylogenetic analysis of 16S rRNA gene sequence showed that strain K3514(T) was affiliated to the genus Lysinibacillus, with its closest relatives being Lysinibacillus mangiferihumi (98.3% sequence similarity), Lysinibacillus sphaericus (97.9% sequence similarity), Lysinibacillus fusiformis (97.4% sequence similarity), and Lysinibacillus xylanilyticus (97.3% sequence similarity). However, low levels of DNA-DNA relatedness values suggested that the isolate was distinct from the other closest Lysinibacillus species. Additionally, based on analysis of morphological, physiological, and biochemical characteristics, the isolate could be differentiated from the closest known relatives. Therefore, based on polyphasic taxonomic data, the novel isolate likely represents a novel species, for which the name Lysinibacillus tabacifolii sp. nov. and the type strain K3514(T) (=KCTC 33042(T) =CCTCC AB 2012050(T)) are proposed.

  10. Copper-mediated oxidative burst in Nicotiana tabacum L. cv. Bright Yellow 2 cell suspension cultures.

    PubMed

    Raeymaekers, T; Potters, G; Asard, H; Guisez, Y; Horemans, N

    2003-05-01

    In cell suspension cultures of Nicotiana tabacum L. cv. Bright Yellow 2 (BY-2) a rapid and concentration-dependent accumulation of H(2)O(2) is induced by excess concentrations of copper (up to 100 microM). This specific and early response towards copper stress was shown to be extracellular. Addition of 300 U of catalase per ml decreased the level of H(2)O(2). Superoxide dismutase (5 U/ml) induced an increase in H(2)O(2) production by 22.2%. This indicates that at least part of the H(2)O(2) is produced by dismutation of superoxide. Pretreatment of the cell cultures with the NAD(P)H oxidase inhibitors diphenylene iodonium (2 and 10 microM) and quinacrine (1 and 5 mM) prevented the generation of H(2)O(2) under copper stress for 90%. The influence of the pH on the H(2)O(2) production revealed the possible involvement of cell-wall-dependent peroxidases in the generation of reactive oxygen species after copper stress.

  11. In vitro antioxidant properties of flavonoids and polysaccharides extract from tobacco (Nicotiana tabacum L.) leaves.

    PubMed

    Ru, Qiao-Mei; Wang, Li-Juan; Li, Wei-Ming; Wang, Jing-Lu; Ding, Yu-Ting

    2012-09-21

    In the present study, antioxidant properties of flavonoids and polysaccharides from tobacco (Nicotiana tabacum L.) leaves were evaluated in several in vitro systems, e.g., scavenging activities on hydroxyl, superoxide anion, 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radicals, and reducing power. Flavonoids showed much better activity than polysaccharides in scavenging activities on free radicals. When compared to the positive control, ascorbic acid, both showed weaker antioxidant potential. However, flavonoids possessed comparable superoxide anion, DPPH and ABTS radical scavenging abilities to ascorbic acid at high concentration (600 μg/mL). Meanwhile, it was found that flavonoids had prominent effects on the reducing power, which was equivalent to ascorbic acid, and was significantly higher than polysaccharides. These results clearly indicate that flavonoids are effective in scavenging free radicals and have the potential to be powerful antioxidants. Thus, tobacco leaves could be considered as a potential source of natural antioxidants for food, pharmaceutical, cosmetics or nutraceutical industries.

  12. Development and application of an efficient virus-induced gene silencing system in Nicotiana tabacum using geminivirus alphasatellite*

    PubMed Central

    Huang, Chang-jun; Zhang, Tong; Li, Fang-fang; Zhang, Xin-yue; Zhou, Xue-ping

    2011-01-01

    Virus-induced gene silencing (VIGS) is a recently developed technique for characterizing the function of plant genes by gene transcript suppression and is increasingly used to generate transient loss-of-function assays. Here we report that the 2mDNA1, a geminivirus satellite vector, can induce efficient gene silencing in Nicotiana tabacum with Tobacco curly shoot virus. We have successfully silenced the β-glucuronidase (GUS) gene in GUS transgenic N. tabacum plants and the sulphur desaturase (Su) gene in five different N. tabacum cultivars. These pronounced and severe silencing phenotypes are persistent and ubiquitous. Once initiated in seedlings, the silencing phenotype lasted for the entire life span of the plants and silencing could be induced in a variety of tissues and organs including leaf, shoot, stem, root, and flower, and achieved at any growth stage. This system works well between 18–32 °C. We also silenced the NtEDS1 gene and demonstrated that NtEDS1 is essential for N gene mediated resistance against Tobacco mosaic virus in N. tabacum. The above results indicate that this system has great potential as a versatile VIGS system for routine functional analysis of genes in N. tabacum. PMID:21265040

  13. Asymmetric hybridization between Nicotiana tabacum and N. repanda by donor recipient protoplast fusion: transfer of TMV resistance.

    PubMed

    Bates, G W

    1990-10-01

    Genetically asymmetric hybrids were recovered by fusion of Nicotiana tabacum protoplasts with irradiated protoplasts of kanamycin-resistant, nopalineproducing plants of N. repanda. Hybrid calli were selected by culture on media containing kanamycin and were regenerated. These plants were morphologically similar to N. tabacum but produced nopaline, indicating they retained genes from N. repanda. Esterase isozyme profiles also indicated that the plants are somatic hybrids, but are more similar to N. tabacum than N. repanda. Chromosome counts showed most of the hybrids had 55-62 chromosomes, which is consistent with extensive, although incomplete elimination of N. repanda chromosomes. The hybrids were largely male sterile, but about half of them set seed when crossed with N. tabacum. Chromosome numbers of the progeny and the pattern of inheritance of kanamycin resistance indicated the continued elimination of N. repanda genetic material in these backcrosses. The N. repanda parent used in these fusions gave a hypersensitive response to TMV, whereas the N. tabacum parent was TMV sensitive. When inoculated with TMV, plants from two hybrid clones gave a hypersensitive response. Plants from the other clones became systemically infected with the virus.

  14. Increased Salt and Drought Tolerance by D-Ononitol Production in Transgenic Nicotiana tabacum L.

    PubMed Central

    Sheveleva, E.; Chmara, W.; Bohnert, H. J.; Jensen, R. G.

    1997-01-01

    A cDNA encoding myo-inositol O-methyltransferase (IMT1) has been transferred into Nicotiana tabacum cultivar SR1. During drought and salt stress, transformants (I5A) accumulated the methylated inositol D-ononitol in amounts exceeding 35 [mu]mol g-1 fresh weight In I5A, photosynthetic CO2 fixation was inhibited less during salt stress and drought, and the plants recovered faster than wild type. One day after rewatering drought-stressed plants, I5A photosynthesis had recovered 75% versus 57% recovery with cultivar SR1 plants. After 2.5 weeks of 250 mM NaCl in hydroponic solution, I5A fixed 4.9 [plus or minus] 1.4 [mu]mol CO2 m-2 s-1, whereas SR1 fixed 2.5 [plus or minus] 0.6 [mu]mol CO2 m-2 s-1. myo-Inositol, the substrate for IMT1, increases in tobacco under stress. Preconditioning of I5A plants in 50 mM NaCl increased D-ononitol amounts and resulted in increased protection when the plants were stressed subsequently with 150 mM NaCl. Pro, Suc, Fru, and Glc showed substantial diurnal fluctuations in amounts, but D-ononitol did not. Plant transformation resulting in stress-inducible, stable solute accumulation appears to provide better protection under drought and salt-stress conditions than strategies using osmotic adjustment by metabolites that are constitutively present. PMID:12223867

  15. Biocatalytic Asymmetric Alkene Reduction: Crystal Structure and Characterization of a Double Bond Reductase from Nicotiana tabacum

    PubMed Central

    2013-01-01

    The application of biocatalysis for the asymmetric reduction of activated C=C is a powerful tool for the manufacture of high-value chemical commodities. The biocatalytic potential of “-ene” reductases from the Old Yellow Enzyme (OYE) family of oxidoreductases is well-known; however, the specificity of these enzymes toward mainly small molecule substrates has highlighted the need to discover “-ene” reductases from different enzymatic classes to broaden industrial applicability. Here, we describe the characterization of a flavin-free double bond reductase from Nicotiana tabacum (NtDBR), which belongs to the leukotriene B4 dehydrogenase (LTD) subfamily of the zinc-independent, medium chain dehydrogenase/reductase superfamily of enzymes. Using steady-state kinetics and biotransformation reactions, we have demonstrated the regio- and stereospecificity of NtDBR against a variety of α,β-unsaturated activated alkenes. In addition to catalyzing the reduction of typical LTD substrates and several classical OYE-like substrates, NtDBR also exhibited complementary activity by reducing non-OYE substrates (i.e., reducing the exocyclic C=C double bond of (R)-pulegone) and in some cases showing an opposite stereopreference in comparison with the OYE family member pentaerythritol tetranitrate (PETN) reductase. This serves to augment classical OYE “-ene” reductase activity and, coupled with its aerobic stability, emphasizes the potential industrial value of NtDBR. Furthermore, we also report the X-ray crystal structures of the holo-, binary NADP(H)-bound, and ternary [NADP+ and 4-hydroxy-3-methoxycinnamaldehyde (9a)-bound] NtDBR complexes. These will underpin structure-driven site-saturated mutagenesis studies aimed at enhancing the reactivity, stereochemistry, and specificity of this enzyme. PMID:27547488

  16. Association of carbonic anhydrase with a Calvin cycle enzyme complex in Nicotiana tabacum.

    PubMed

    Jebanathirajah, J A; Coleman, J R

    1998-02-01

    Chloroplast-localized carbonic anhydrase (CA; EC 4.2.1.1), an enzyme which catalyzes the reversible hydration of CO2, appears to be associated with other enzymes of the Calvin cycle in a large multienzyme complex. Gel-filtration fast protein liquid chromatography (FPLC) of soluble proteins obtained by osmotic lysis of tobacco (Nicotiana tabacum L. cv. Carlson) chloroplasts results in the co-elution of a protein complex of greater than 600 kDa which includes CA, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), phosphoribulokinase (PRK), and ribose-5-phosphate isomerase. Anion-exchange FPLC of chloroplast extracts indicates that there is an association of CA with other proteins that modifies its elution profile in a NaCl gradient, and that Rubisco co-elutes with the fractions containing CA. Following a protocol described by Süss et al. (1993, Proc Natl Acad Sci USA 90: 5514-5518), limited protease treatment of chloroplast extracts was used to show that the association of PRK with other chloroplast proteins appears to protect a number of lysine and arginine residues which may be involved in specific protein-protein interactions. A similar treatment of CA indicates some protection of these residues when CA is associated with other chloroplast polypeptides but the level of protection is not as profound as that exhibited by PRK. In concert with previously published immunolocalization studies, these data indicate that CA may be associated with Rubisco at the stromal periphery of a Calvin cycle enzyme complex in which PRK is more centrally located and associated with thylakoid membranes.

  17. Profiling of Altered Metabolomic States in Nicotiana tabacum Cells Induced by Priming Agents

    PubMed Central

    Mhlongo, Msizi I.; Steenkamp, Paul A.; Piater, Lizelle A.; Madala, Ntakadzeni E.; Dubery, Ian A.

    2016-01-01

    Metabolomics has developed into a valuable tool for advancing our understanding of plant metabolism. Plant innate immune defenses can be activated and enhanced so that, subsequent to being pre-sensitized, plants are able to launch a stronger and faster defense response upon exposure to pathogenic microorganisms, a phenomenon known as priming. Here, three contrasting chemical activators, namely acibenzolar-S-methyl, azelaic acid and riboflavin, were used to induce a primed state in Nicotiana tabacum cells. Identified biomarkers were then compared to responses induced by three phytohormones—abscisic acid, methyljasmonate, and salicylic acid. Altered metabolomes were studied using a metabolite fingerprinting approach based on liquid chromatography and mass spectrometry. Multivariate data models indicated that these inducers cause time-dependent metabolic perturbations in the cultured cells and revealed biomarkers of which the levels are affected by these agents. A total of 34 metabolites were annotated from the mass spectral data and online databases. Venn diagrams were used to identify common biomarkers as well as those unique to a specific agent. Results implicate 20 cinnamic acid derivatives conjugated to (i) quinic acid (chlorogenic acids), (ii) tyramine, (iii) polyamines, or (iv) glucose as discriminatory biomarkers of priming in tobacco cells. Functional roles for most of these metabolites in plant defense responses could thus be proposed. Metabolites induced by the activators belong to the early phenylpropanoid pathway, which indicates that different stimuli can activate similar pathways but with different metabolite fingerprints. Possible linkages to phytohormone-dependent pathways at a metabolomic level were indicated in the case of cells treated with salicylic acid and methyljasmonate. The results contribute to a better understanding of the priming phenomenon and advance our knowledge of cinnamic acid derivatives as versatile defense metabolites. PMID

  18. Elucidating the physiological and biochemical responses of different tobacco (Nicotiana tabacum) genotypes to lead toxicity.

    PubMed

    Maodzeka, Antony; Hussain, Nazim; Wei, Liquan; Zvobgo, Gerald; Mapodzeke, James Mutemachani; Adil, Muhammad Faheem; Jabeen, Salma; Wang, Feng; Jiang, Lixi; Shamsi, Imran Haider

    2017-01-01

    In the present study, the effects of lead (Pb) uptake and toxicity were investigated in a hydroponic culture using 7 tobacco (Nicotiana tabacum L.) genotypes (Bina 1 [B1], Kutsaga Mammoth 10 [KM10], Nanjing 3 [N3], Kutsaga 35 [K35], Kutsaga E1 [KE1], Cocker 176 [C176], and Kutsaga RK6 [KRK6]) that differed in Pb tolerance. Lead was applied as a solution of Pb nitrate at concentrations of 0 μM, 10 μM, 250 μM, and 500 μM. After 4 wk of Pb treatment, tissue biomass and photosynthetic parameters were measured and elemental analysis was performed. The results showed decreases in growth and photosynthetic parameters with increases in Pb concentration compared with the control. The least reduction in the recorded physiological parameters was noted in K35, whereas the greatest reduction was observed in N3, which is an obvious indication of genotypic differences. Activities of peroxidase, catalase, and malondialdehyde increased significantly with increases in Pb concentration, with genotypes K35 and N3 showing the least and the greatest reduction, respectively. The results demonstrate the phototoxic nature of Pb on plants, and it can be concluded that in Pb-prone areas genotypes K35 and B1 can be used for cultivation because they can grow efficiently in the presence of high Pb concentrations while restricting Pb uptake in the aboveground parts, as seen by the higher Pb tolerance index. Environ Toxicol Chem 2017;36:175-181. © 2016 SETAC.

  19. Glutathione Transferase from Trichoderma virens Enhances Cadmium Tolerance without Enhancing Its Accumulation in Transgenic Nicotiana tabacum

    PubMed Central

    Dixit, Prachy; Mukherjee, Prasun K.; Ramachandran, V.; Eapen, Susan

    2011-01-01

    Background Cadmium (Cd) is a major heavy metal pollutant which is highly toxic to plants and animals. Vast agricultural areas worldwide are contaminated with Cd. Plants take up Cd and through the food chain it reaches humans and causes toxicity. It is ideal to develop plants tolerant to Cd, without enhanced accumulation in the edible parts for human consumption. Glutathione transferases (GST) are a family of multifunctional enzymes known to have important roles in combating oxidative stresses induced by various heavy metals including Cd. Some GSTs are also known to function as glutathione peroxidases. Overexpression/heterologous expression of GSTs is expected to result in plants tolerant to heavy metals such as Cd. Results Here, we report cloning of a glutathione transferase gene from Trichoderma virens, a biocontrol fungus and introducing it into Nicotiana tabacum plants by Agrobacterium-mediated gene transfer. Transgenic nature of the plants was confirmed by Southern blot hybridization and expression by reverse transcription PCR. Transgene (TvGST) showed single gene Mendelian inheritance. When transgenic plants expressing TvGST gene were exposed to different concentrations of Cd, they were found to be more tolerant compared to wild type plants, with transgenic plants showing lower levels of lipid peroxidation. Levels of different antioxidant enzymes such as glutathione transferase, superoxide dismutase, ascorbate peroxidase, guiacol peroxidase and catalase showed enhanced levels in transgenic plants expressing TvGST compared to control plants, when exposed to Cd. Cadmium accumulation in the plant biomass in transgenic plants were similar or lower than wild-type plants. Conclusion The results of the present study suggest that transgenic tobacco plants expressing a Trichoderma virens GST are more tolerant to Cd, without enhancing its accumulation in the plant biomass. It should be possible to extend the present results to crop plants for developing Cd tolerance and

  20. The Sclerophyllous Eucalyptus camaldulensis and Herbaceous Nicotiana tabacum Have Different Mechanisms to Maintain High Rates of Photosynthesis

    PubMed Central

    Huang, Wei; Tong, You-Gui; Yu, Guo-Yun; Yang, Wei-Xian

    2016-01-01

    It is believed that high levels of mesophyll conductance (gm) largely contribute to the high rates of photosynthesis in herbaceous C3 plants. However, some sclerophyllous C3 plants that display low levels of gm have high rates of photosynthesis, and the underlying mechanisms responsible for high photosynthetic rates in sclerophyllous C3 plants are unclear. In the present study, we examined photosynthetic characteristics in two high-photosynthesis plants (the sclerophyllous Eucalyptus camaldulensis and the herbaceous Nicotiana tabacum) using measurements of gas exchange and chlorophyll fluorescence. Under saturating light intensities, both species had similar rates of CO2 assimilation at 400 μmol mol−1 CO2 (A400). However, E. camaldulensis exhibited significantly lower gm and chloroplast CO2 concentration (Cc) than N. tabacum. A quantitative analysis revealed that, in E. camaldulensis, the gm limitation was the most constraining factor for photosynthesis. By comparison, in N. tabacum, the biochemical limitation was the strongest, followed by gm and gs limitations. In conjunction with a lower Cc, E. camaldulensis up-regulated the capacities of photorespiratory pathway and alternative electron flow. Furthermore, the rate of alternative electron flow was positively correlated with the rates of photorespiration and ATP supply from other flexible mechanisms, suggesting the important roles of photorespiratory pathway, and alternative electron flow in sustaining high rate of photosynthesis in E. camaldulensis. These results highlight the different mechanisms used to maintain high rates of photosynthesis in the sclerophyllous E. camaldulensis and the herbaceous N. tabacum. PMID:27933083

  1. Biological and chemical induction of resistance to the Globodera tabacum solanacearum in oriental and flue-cured tobacco (Nicotiana tabacum L.).

    PubMed

    Parkunan, Venkatesan; Johnson, Charles S; Eisenback, Jon D

    2009-09-01

    The effects of acibenzolar-S-methyl (ASM) and four combinations of plant growth-promoting rhizobacteria (PGPR) on the reproduction of a tobacco cyst nematode, Globodera tabacum solanacearum, and growth of Nicotiana tabacum (cv. K326 and Xanthi) were tested under greenhouse and field conditions. The PGPR included combinations of Bacillus subtilis A13 with B. pumilis INR7, B. pumilis SE34, B. licheniformis IN937b, or B. amyloliquefaciens IN937a, respectively. Among the four rhizobacterial combinations, IN937a + A13 exhibited the most consistent reduction in G. t. solanacearum cysts under greenhouse and field conditions. No undesirable effects of IN937a + A13 were observed on tobacco growth under greenhouse and field conditions. Use of INR7 + A13 reduced G. t. solanacearum reproduction on flue-cured tobacco cv. K326 but not on oriental tobacco cv. Xanthi. Application of ASM reduced final numbers of G. t. solanacearum cysts, but also resulted in phytotoxicity mainly under the greenhouse conditions. When oriental tobacco seedlings were pre-grown in a IN937a + A13-treated soil-less medium, a single application of ASM at 200 mg/L one week after transplanting significantly reduced G. t. solanacearum reproduction in the field.

  2. Biological and Chemical Induction of Resistance to the Globodera tabacum solanacearum in Oriental and Flue-Cured Tobacco (Nicotiana tabacum L.)

    PubMed Central

    Johnson, Charles S.; Eisenback, Jon D.

    2009-01-01

    The effects of acibenzolar-S-methyl (ASM) and four combinations of plant growth-promoting rhizobacteria (PGPR) on the reproduction of a tobacco cyst nematode, Globodera tabacum solanacearum, and growth of Nicotiana tabacum (cv. K326 and Xanthi) were tested under greenhouse and field conditions. The PGPR included combinations of Bacillus subtilis A13 with B. pumilis INR7, B. pumilis SE34, B. licheniformis IN937b, or B. amyloliquefaciens IN937a, respectively. Among the four rhizobacterial combinations, IN937a + A13 exhibited the most consistent reduction in G. t. solanacearum cysts under greenhouse and field conditions. No undesirable effects of IN937a + A13 were observed on tobacco growth under greenhouse and field conditions. Use of INR7 + A13 reduced G. t. solanacearum reproduction on flue-cured tobacco cv. K326 but not on oriental tobacco cv. Xanthi. Application of ASM reduced final numbers of G. t. solanacearum cysts, but also resulted in phytotoxicity mainly under the greenhouse conditions. When oriental tobacco seedlings were pre-grown in a IN937a + A13-treated soil-less medium, a single application of ASM at 200 mg/L one week after transplanting significantly reduced G. t. solanacearum reproduction in the field. PMID:22736815

  3. Cloning of the Lycopene β-cyclase Gene in Nicotiana tabacum and Its Overexpression Confers Salt and Drought Tolerance

    PubMed Central

    Shi, Yanmei; Guo, Jinggong; Zhang, Wei; Jin, Lifeng; Liu, Pingping; Chen, Xia; Li, Feng; Wei, Pan; Li, Zefeng; Li, Wenzheng; Wei, Chunyang; Zheng, Qingxia; Chen, Qiansi; Zhang, Jianfeng; Lin, Fucheng; Qu, Lingbo; Snyder, John Hugh; Wang, Ran

    2015-01-01

    Carotenoids are important pigments in plants that play crucial roles in plant growth and in plant responses to environmental stress. Lycopene β cyclase (β-LCY) functions at the branch point of the carotenoid biosynthesis pathway, catalyzing the cyclization of lycopene. Here, a β-LCY gene from Nicotiana tabacum, designated as Ntβ-LCY1, was cloned and functionally characterized. Robust expression of Ntβ-LCY1 was found in leaves, and Ntβ-LCY1 expression was obviously induced by salt, drought, and exogenous abscisic acid treatments. Strong accumulation of carotenoids and expression of carotenoid biosynthesis genes resulted from Ntβ-LCY1 overexpression. Additionally, compared to wild-type plants, transgenic plants with overexpression showed enhanced tolerance to salt and drought stress with higher abscisic acid levels and lower levels of malondialdehyde and reactive oxygen species. Conversely, transgenic RNA interference plants had a clear albino phenotype in leaves, and some plants did not survive beyond the early developmental stages. The suppression of Ntβ-LCY1 expression led to lower expression levels of genes in the carotenoid biosynthesis pathway and to reduced accumulation of carotenoids, chlorophyll, and abscisic acid. These results indicate that Ntβ-LCY1 is not only a likely cyclization enzyme involved in carotenoid accumulation but also confers salt and drought stress tolerance in Nicotiana tabacum. PMID:26703579

  4. Analysis of Nicotiana tabacum PIN genes identifies NtPIN4 as a key regulator of axillary bud growth.

    PubMed

    Xie, Xiaodong; Qin, Guangyong; Si, Ping; Luo, Zhaopeng; Gao, Junping; Chen, Xia; Zhang, Jianfeng; Wei, Pan; Xia, Qingyou; Lin, Fucheng; Yang, Jun

    2017-01-27

    The plant-specific PIN-FORMED (PIN) auxin efflux proteins have been well characterized in many plant species, where they are crucial in the regulation of auxin transport in various aspects of plant development. However, little is known about the exact roles of the PIN genes during plant development in Nicotiana species. This study investigated the PIN genes in tobacco (N. tabacum) and in two ancestral species (N. sylvestris and N. tomentosiformis). Genome-wide analysis of the N. tabacum genome identified 20 genes of the PIN family. An in-depth phylogenetic analysis of the PIN genes of N. tabacum, N. sylvestris and N. tomentosiformis was conducted. NtPIN4 expression was strongly induced by the application of exogenous IAA, but was downregulated by the application of ABA, a strigolactone analogue, and cytokinin, as well as by decapitation treatments, suggesting that the NtPIN4 expression level is likely positively regulated by auxin. Expression analysis indicated that NtPIN4 was highly expressed in tobacco stems and shoots, which was further validated through analysis of the activity of the NtPIN4 promoter. We used CRISPR-Cas9 technology to generate mutants for NtPIN4 and observed that both T0 and T1 plants had a significantly increased axillary bud growth phenotype, as compared with the wild-type plants. Therefore, NtPIN4 offers an opportunity for studying auxin-dependent branching processes.

  5. Ectopic expression of class 1 KNOX genes induce and adventitious shoot regeneration and alter growth and development of tobacco (Nicotiana tabacum L) and European plum (Prunus domestica L)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Transgenic plants of tobacco (Nicotiana tabacum L) and plum (Prunus domestica L) were produced by transforming with apple class 1 KNOX genes (MdKN1 and MdKN2) or corn KN1 gene. Transgenic tobacco plants were regenerated in vitro from transformed leaf discs cultured in a tissue medium lacking cytoki...

  6. Herbivore induction of jasmonic acid and chemical defences reduce photosynthesis in Nicotiana attenuata.

    PubMed

    Nabity, Paul D; Zavala, Jorge A; DeLucia, Evan H

    2013-01-01

    Herbivory initiates a shift in plant metabolism from growth to defence that may reduce fitness in the absence of further herbivory. However, the defence-induced changes in carbon assimilation that precede this reallocation in resources remain largely undetermined. This study characterized the response of photosynthesis to herbivore induction of jasmonic acid (JA)-related defences in Nicotiana attenuata to increase understanding of these mechanisms. It was hypothesized that JA-induced defences would immediately reduce the component processes of photosynthesis upon attack and was predicted that wild-type plants would suffer greater reductions in photosynthesis than plants lacking JA-induced defences. Gas exchange, chlorophyll fluorescence, and thermal spatial patterns were measured together with the production of defence-related metabolites after attack and through recovery. Herbivore damage immediately reduced electron transport and gas exchange in wild-type plants, and gas exchange remained suppressed for several days after attack. The sustained reductions in gas exchange occurred concurrently with increased defence metabolites in wild-type plants, whereas plants lacking JA-induced defences suffered minimal suppression in photosynthesis and no increase in defence metabolite production. This suppression in photosynthesis occurred only after sustained defence signalling and defence chemical mobilization, whereas a short bout of feeding damage only transiently altered components of photosynthesis. It was identified that lipoxygenase signalling interacted with photosynthetic electron transport and that the resulting JA-related metabolites reduced photosynthesis. These data represent a metabolic cost to mounting a chemical defence against herbivory and link defence-signalling networks to the differential effects of herbivory on photosynthesis in remaining leaf tissues in a time-dependent manner.

  7. Ionome changes in Xylella fastidiosa-infected Nicotiana tabacum correlate with virulence and discriminate between subspecies of bacterial isolates.

    PubMed

    Oliver, J E; Sefick, S A; Parker, J K; Arnold, T; Cobine, P A; De La Fuente, L

    2014-10-01

    Characterization of ionomes has been used to uncover the basis of nutrient utilization and environmental adaptation of plants. Here, ionomic profiles were used to understand the phenotypic response of a plant to infection by genetically diverse isolates of Xylella fastidiosa, a gram-negative, xylem-limited bacterial plant pathogen. In this study, X. fastidiosa isolates were used to infect a common model host (Nicotiana tabacum 'SR1'), and leaf and sap concentrations of eleven elements together with plant colonization and symptoms were assessed. Multivariate statistical analysis revealed that changes in the ionome were significantly correlated with symptom severity and bacterial populations in host petioles. Moreover, plant ionome modification by infection could be used to differentiate the X. fastidiosa subspecies with which the plant was infected. This report establishes host ionome modification as a phenotypic response to infection.

  8. Organ- and Growing Stage-Specific Expression of Solanesol Biosynthesis Genes in Nicotiana tabacum Reveals Their Association with Solanesol Content.

    PubMed

    Yan, Ning; Zhang, Hongbo; Zhang, Zhongfeng; Shi, John; Timko, Michael P; Du, Yongmei; Liu, Xinmin; Liu, Yanhua

    2016-11-15

    Solanesol is a noncyclic terpene alcohol that is composed of nine isoprene units and mainly accumulates in solanaceous plants, especially tobacco (Nicotiana tabacum L.). In the present study, RNA-seq analyses of tobacco leaves, stems, and roots were used to identify putative solanesol biosynthesis genes. Six 1-deoxy-d-xylulose 5-phosphate synthase (DXS), two 1-deoxy-d-xylulose 5-phosphate reductoisomerase (DXR), two 2-C-methyl-d-erythritol 4-phosphate cytidylyltransferase (IspD), four 4-diphosphocytidyl-2-C-methyl-d-erythritol kinase (IspE), two 2-C-methyl-d-erythritol 2,4-cyclo-diphosphate synthase (IspF), four 1-hydroxy-2-methyl-2-(E)-butenyl 4-diphosphate synthase (IspG), two 1-hydroxy-2-methyl-2-(E)-butenyl 4-diphosphate reductase (IspH), six isopentenyl diphosphate isomerase (IPI), and two solanesyl diphosphate synthase (SPS) candidate genes were identified in the solanesol biosynthetic pathway. Furthermore, the two N. tabacum SPS proteins (NtSPS1 and NtSPS2), which possessed two conserved aspartate-rich DDxxD domains, were highly homologous with SPS enzymes from other solanaceous plant species. In addition, the solanesol contents of three organs and of leaves from four growing stages of tobacco plants corresponded with the distribution of chlorophyll. Our findings provide a comprehensive evaluation of the correlation between the expression of different biosynthesis genes and the accumulation of solanesol, thus providing valuable insight into the regulation of solanesol biosynthesis in tobacco.

  9. Species origin of genomic factors in Nicotiana nudicaulis Watson controlling hybrid lethality in interspecific hybrids between N. nudicaulis Watson and N. tabacum L.

    PubMed

    Liu, Hongshuo; Marubashi, Wataru

    2014-01-01

    Hybrid lethality is expressed at 28°C in the cross Nicotiana nudicaulis × N. tabacum. The S subgenome of N. tabacum has been identified as controlling this hybrid lethality. To clarify the responsible genomic factor(s) of N. nudicaulis, we crossed N. trigonophylla (paternal progenitor of N. nudicaulis) with N. tabacum, because hybrids between N. sylvestris (maternal progenitor of N. nudicaulis) and N. tabacum are viable when grown in a greenhouse. In the cross N. trigonophylla×N. tabacum, approximately 50% of hybrids were vitrified, 20% were viable, and 20% were nonviable at 28°C. To reveal which subgenome of N. tabacum was responsible for these phenotypes, we crossed N. trigonophylla with two progenitors of N. tabacum, N. sylvestris (SS) and N. tomentosiformis (TT). In the cross N. sylvestris × N. trigonophylla, we confirmed that over half of hybrids of N. sylvestris × N. trigonophylla were vitrified, and none of the hybrids of N. trigonophylla × N. tomentosiformis were. The results imply that the S subgenome, encoding a gene or genes inducing hybrid lethality in the cross between N. nudicaulis and N. tabacum, has one or more genomic factors that induce vitrification. Furthermore, in vitrified hybrids of N. trigonophylla × N. tabacum and N. sylvestris × N. trigonophylla, we found that nuclear fragmentation, which progresses during expression of hybrid lethality, was accompanied by vitrification. This observation suggests that vitrification has a relationship to hybrid lethality. Based on these results, we speculate that when N. nudicaulis was formed approximately 5 million years ago, several causative genomic factors determining phenotypes of hybrid seedlings were inherited from N. trigonophylla. Subsequently, genome downsizing and various recombination-based processes took place. Some of the causative genomic factors were lost and some became genomic factor(s) controlling hybrid lethality in extant N. nudicaulis.

  10. OBSERVATIONS ON THE SUSCEPTIBILITY OF SOME WILD SPECIES OF THE GENUS NICOTINA AND OF SOME VARIETIES OF NICOTIANA TABACUM L. AND N. RUSTICA L. TO BLUE MOULD (PERONOSPORA TABACINA ADAM) -- PULAWY 1962

    DTIC Science & Technology

    Observations on the susceptibility of some wild species of the genus nicotina and of some varieties of nicotiana tabacum l. and n. rustica l. to blue mould (peronospora tabacina adam) -- pulawy 1962--Translation.

  11. RNA-Dependent RNA Polymerase 1 from Nicotiana tabacum Suppresses RNA Silencing and Enhances Viral Infection in Nicotiana benthamiana[W

    PubMed Central

    Ying, Xiao-Bao; Dong, Li; Zhu, Hui; Duan, Cheng-Guo; Du, Quan-Sheng; Lv, Dian-Qiu; Fang, Yuan-Yuan; Garcia, Juan Antonio; Fang, Rong-Xiang; Guo, Hui-Shan

    2010-01-01

    Endogenous eukaryotic RNA-dependent RNA polymerases (RDRs) produce double-stranded RNA intermediates in diverse processes of small RNA synthesis in RNA silencing pathways. RDR6 is required in plants for posttranscriptional gene silencing induced by sense transgenes (S-PTGS) and has an important role in amplification of antiviral silencing. Whereas RDR1 is also involved in antiviral defense in plants, this does not necessarily proceed through triggering silencing. In this study, we show that Nicotiana benthamiana transformed with RDR1 from Nicotiana tabacum (Nt-RDR1 plants) exhibits hypersusceptibility to Plum pox potyvirus and other viruses, resembling RDR6-silenced (RDR6i) N. benthamiana. Analysis of transient induction of RNA silencing in N. benthamiana Nt-RDR1 and RDR6i plants revealed that Nt-RDR1 possesses silencing suppression activity. We found that Nt-RDR1 does not interfere with RDR6-dependent siRNA accumulation but turns out to suppress RDR6-dependent S-PTGS. Our results, together with previously published data, suggest that RDR1 might have a dual role, contributing, on one hand, to salicylic acid–mediated antiviral defense, and suppressing, on the other hand, the RDR6-mediated antiviral RNA silencing. We propose a scenario in which the natural loss-of-function variant of RDR1 in N. benthamiana may be the outcome of selective pressure to maintain a high RDR6-dependent antiviral defense, which would be required to face the hypersensitivity of this plant to a large number of viruses. PMID:20400679

  12. Enhancement of cadmium tolerance and accumulation by introducing Perilla frutescens (L.) Britt var. frutescens genes in Nicotiana tabacum L. plants.

    PubMed

    Wei, Keqiang; Pang, Shengxi; Yang, Junxian; Wei, Zhizhong

    2015-04-01

    The tobacco has the genetic potential to remove toxic metals from the soil. To develop hyperaccumulating tobacco plants, distant hybridization between tobacco (Nicotiana tabacum L.), a high-biomass crop, and Perilla frutescens (L.) Britt var. frutescens, a newfound Cd-hyperaccumulator species, was carried out using a novel method viz. pollination following grafting. Their hybrid nature was preliminarily confirmed by phenotype, isozyme pattern, random amplified polymorphic DNA (RAPD) and metabolites analysis. About 120 putative F2 hybrids derived from the cross-combination [(N. sylvestris Speg. & Comes rootstock + N. tabacum L. var. 78-04 scion) × P. frutescens (L.) Britt var. frutescens] were then subjected to up to 300 μM CdCl2 in hydroponic conditions for 10 days. Results showed five seedlings were more resistant to Cd than female parent and accumulated 314.6 ± 99.9 mg kg(-1) Cd in their aerial biomass, which was 5.7 times greater than that in "78-04" tobacco (47.2 ± 3.56 mg kg(-1)) (P ≤ 0.05). Two of these seedlings exceeded male parent P. frutescens in the Cd concentration of shoots and reached 424 and 396 mg kg(-1), which was 13% and 6% greater for that of perilla (374.2 ± 10.38 mg kg(-1)), respectively. Compared with parents, two other F2 hybrids tended to accumulate more Cd in the root with bioconcentration factor (BCF) 7.05 and 5.17, respectively. Only one hybrid showed lower Cd concentration but transferred Cd more effectively from the root to the shoot than parents and other F2 hybrids, with the maximum translocation factor (TF) value 1.37. These indicated that the introduction of P. frutescens genes could obviously enhance the cadmium tolerance and accumulation of superior individuals.

  13. Low-temperature derivatization followed by vortex-assisted liquid-liquid microextraction for the analysis of polyamines in Nicotiana Tabacum.

    PubMed

    Cai, Kai; Cai, Bin; Xiang, Zhangmin; Zhao, Huina; Rao, Xingyi; Pan, Wenjie; Lei, Bo

    2016-07-01

    Polyamines are ubiquitous polycationic molecules that play a key role in many biological processes such as nucleic acid metabolism, protein synthesis, cell growth, and nicotine synthesis precursors. This work describes a rapid, sensitive, convenient, green, and cost-effective method for the determination of polyamines in Nicotiana tabacum by ultra high performance liquid chromatography with photodiode array detection. The analytes were derivatized with 3,5-dinitrobenzoyl chloride at low temperature (about 4°C) and then extracted with vortex-assisted liquid-liquid microextraction. The experimental designs based on quarter-fractional factorial design and Doehlert design were used to screen and optimize the important factors in microextraction process. Under the optimal conditions, the method was linear over 0.05-8.00 μg/mL with an r(2) ≥ 0.992 and exhibited good repeatability and reproducibility less than 6.0 and 6.9%, respectively. The limit of detection ranged between 0.013 and 0.029 μg/g. The newly developed method was successfully employed to analyze different leaf samples of Nicotiana tabacum, among which the polyamines contents were found to be very different. Moreover, tyramine, 1,3-diaminopropane, homospermidine, and canavalmine were tentatively identified with the electrospray ionization quadrupole time-of-flight mass spectrometry. To our knowledge, this is the first report of identification of canavalmine in Nicotiana Tabacum.

  14. Effects of down-regulating ornithine decarboxylase upon putrescine-associated metabolism and growth in Nicotiana tabacum L.

    PubMed Central

    Dalton, Heidi L.; Blomstedt, Cecilia K.; Neale, Alan D.; Gleadow, Ros; DeBoer, Kathleen D.; Hamill, John D.

    2016-01-01

    Transgenic plants of Nicotiana tabacum L. homozygous for an RNAi construct designed to silence ornithine decarboxylase (ODC) had significantly lower concentrations of nicotine and nornicotine, but significantly higher concentrations of anatabine, compared with vector-only controls. Silencing of ODC also led to significantly reduced concentrations of polyamines (putrescine, spermidine and spermine), tyramine and phenolamides (caffeoylputrescine and dicaffeoylspermidine) with concomitant increases in concentrations of amino acids ornithine, arginine, aspartate, glutamate and glutamine. Root transcript levels of S-adenosyl methionine decarboxylase, S-adenosyl methionine synthase and spermidine synthase (polyamine synthesis enzymes) were reduced compared with vector controls, whilst transcript levels of arginine decarboxylase (putrescine synthesis), putrescine methyltransferase (nicotine production) and multi-drug and toxic compound extrusion (alkaloid transport) proteins were elevated. In contrast, expression of two other key proteins required for alkaloid synthesis, quinolinic acid phosphoribosyltransferase (nicotinic acid production) and a PIP-family oxidoreductase (nicotinic acid condensation reactions), were diminished in roots of odc-RNAi plants relative to vector-only controls. Transcriptional and biochemical differences associated with polyamine and alkaloid metabolism were exacerbated in odc-RNAi plants in response to different forms of shoot damage. In general, apex removal had a greater effect than leaf wounding alone, with a combination of these injury treatments producing synergistic responses in some cases. Reduced expression of ODC appeared to have negative effects upon plant growth and vigour with some leaves of odc-RNAi lines being brittle and bleached compared with vector-only controls. Together, results of this study demonstrate that ornithine decarboxylase has important roles in facilitating both primary and secondary metabolism in Nicotiana. PMID

  15. Effects of down-regulating ornithine decarboxylase upon putrescine-associated metabolism and growth in Nicotiana tabacum L.

    PubMed

    Dalton, Heidi L; Blomstedt, Cecilia K; Neale, Alan D; Gleadow, Ros; DeBoer, Kathleen D; Hamill, John D

    2016-05-01

    Transgenic plants of Nicotiana tabacum L. homozygous for an RNAi construct designed to silence ornithine decarboxylase (ODC) had significantly lower concentrations of nicotine and nornicotine, but significantly higher concentrations of anatabine, compared with vector-only controls. Silencing of ODC also led to significantly reduced concentrations of polyamines (putrescine, spermidine and spermine), tyramine and phenolamides (caffeoylputrescine and dicaffeoylspermidine) with concomitant increases in concentrations of amino acids ornithine, arginine, aspartate, glutamate and glutamine. Root transcript levels of S-adenosyl methionine decarboxylase, S-adenosyl methionine synthase and spermidine synthase (polyamine synthesis enzymes) were reduced compared with vector controls, whilst transcript levels of arginine decarboxylase (putrescine synthesis), putrescine methyltransferase (nicotine production) and multi-drug and toxic compound extrusion (alkaloid transport) proteins were elevated. In contrast, expression of two other key proteins required for alkaloid synthesis, quinolinic acid phosphoribosyltransferase (nicotinic acid production) and a PIP-family oxidoreductase (nicotinic acid condensation reactions), were diminished in roots of odc-RNAi plants relative to vector-only controls. Transcriptional and biochemical differences associated with polyamine and alkaloid metabolism were exacerbated in odc-RNAi plants in response to different forms of shoot damage. In general, apex removal had a greater effect than leaf wounding alone, with a combination of these injury treatments producing synergistic responses in some cases. Reduced expression of ODC appeared to have negative effects upon plant growth and vigour with some leaves of odc-RNAi lines being brittle and bleached compared with vector-only controls. Together, results of this study demonstrate that ornithine decarboxylase has important roles in facilitating both primary and secondary metabolism in Nicotiana.

  16. Priming of anti-herbivore defence in Nicotiana attenuata by insect oviposition: herbivore-specific effects.

    PubMed

    Bandoly, Michele; Grichnik, Roland; Hilker, Monika; Steppuhn, Anke

    2016-04-01

    Oviposition by Spodoptera exigua on Nicotiana attenuata primes plant defence against its larvae that consequently suffer reduced performance. To reveal whether this is a general response of tobacco to insect oviposition or species-specific, we investigated whether also Manduca sexta oviposition primes N. attenuata's anti-herbivore defence. The plant response to M. sexta and S. exigua oviposition overlapped in the egg-primed feeding-induced production of the phenylpropanoid caffeoylputrescine. While M. sexta larvae were unaffected in their performance, they showed a novel response to the oviposition-mediated plant changes: a reduced antimicrobial activity in their haemolymph. In a cross-resistance experiment, S. exigua larvae suffered reduced performance on M. sexta-oviposited plants like they did on S. exigua-oviposited plants. The M. sexta oviposition-mediated plant effects on the S. exigua larval performance and on M. sexta larval immunity required expression of the NaMyb8 transcription factor that is governing biosynthesis of phenylpropanoids such as caffeoylputrescine. Thus, NaMyb8-dependent defence traits mediate the effects that oviposition by both lepidopteran species exerts on the plant's anti-herbivore defence. These results suggest that oviposition by lepidopteran species on N. attenuata leaves may generally prime the feeding-induced production of certain plant defence compounds but that different herbivore species show different susceptibility to egg-primed plant effects.

  17. Gene-Splitting Technology: A Novel Approach for the Containment of Transgene Flow in Nicotiana tabacum

    PubMed Central

    Kong, Ning; Jia, Shi-Rong; Tang, Qiao-Ling; Wang, Zhi-Xing

    2014-01-01

    The potential impact of transgene escape on the environment and food safety is a major concern to the scientists and public. This work aimed to assess the effect of intein-mediated gene splitting on containment of transgene flow. Two fusion genes, EPSPSn-In and Ic-EPSPSc, were constructed and integrated into N. tabacum, using Agrobacterium tumefaciens-mediated transformation. EPSPSn-In encodes the first 295 aa of the herbicide resistance gene 5-enolpyruvyl shikimate-3-phosphate synthase (EPSPS) fused with the first 123 aa of the Ssp DnaE intein (In), whereas Ic-EPSPSc encodes the 36 C-terminal aa of the Ssp DnaE intein (Ic) fused to the rest of EPSPS C terminus peptide sequences. Both EPSPSn-In and Ic-EPSPSc constructs were introduced into the same N. tabacum genome by genetic crossing. Hybrids displayed resistance to the herbicide N-(phosphonomethyl)-glycine (glyphosate). Western blot analysis of protein extracts from hybrid plants identified full-length EPSPS. Furthermore, all hybrid seeds germinated and grew normally on glyphosate selective medium. The 6-8 leaf hybrid plants showed tolerance of 2000 ppm glyphosate in field spraying. These results indicated that functional EPSPS protein was reassembled in vivo by intein-mediated trans-splicing in 100% of plants. In order to evaluate the effect of the gene splitting technique for containment of transgene flow, backcrossing experiments were carried out between hybrids, in which the foreign genes EPSPSn-In and Ic-EPSPSc were inserted into different chromosomes, and non-transgenic plants NC89. Among the 2812 backcrossing progeny, about 25% (664 plantlets) displayed glyphosate resistance. These data indicated that transgene flow could be reduced by 75%. Overall, our findings provide a new and highly effective approach for biological containment of transgene flow. PMID:24915192

  18. Effect of increased UV-B radiation on carotenoid accumulation and total antioxidant capacity in tobacco (Nicotiana tabacum L.) leaves.

    PubMed

    Shen, J; Jiang, C Q; Yan, Y F; Liu, B R; Zu, C L

    2017-03-08

    Carotenoids are important components of plant antioxidant systems, which protect photosystems from photooxidative destruction during ultraviolet-B (UV-B) exposure. The influence of carotenoids on total antioxidant capacity (TAC) of plants has rarely been studied. In this study, tobacco (Nicotiana tabacum L., 'K326') seedlings exposed to UV-B radiation were used in order to evaluate the effects of ambient levels of UV-B radiation on carotenoid accumulation. The aim was to investigate whether carotenoids could enhance TAC as a means of UV protection. Our results showed that leaf carotenoid content in the low UV-B exposure (+9.75 μW/cm(2)) plants was approximately 8% higher than that observed in control plants at 2-8 days of exposure. At high UV-B exposure (+20.76 μW/cm(2)), the carotenoid content increased rapidly after 1 day's exposure (10.41% higher than the control), followed by a return to the content as in control plants. Furthermore, carotenoid content positively correlated with TAC (P = 0.024). These results suggest that carotenoids have antioxidant properties and play an important role in the antioxidant system. UV-B exposure increased the carotenoid synthesis capability of plants. The plants could deplete the carotenoids to scavenge excess ROS at high UV-B radiation levels, which protects the tobacco plant from oxidative damage caused by UV-B stress.

  19. Early inhibition of photosynthesis during development of Mn toxicity in tobacco. [Nicotiana tabacum L. cv KY14

    SciTech Connect

    Nable, R.O.; Houtz, R.L.; Cheniae, G.M. )

    1988-04-01

    Early physiological effects of developing Mn toxicity in young leaves of burley tobacco (Nicotiana tabacum L. cv KY 14) were examined in glass-house/water cultured plants grown at high (summer) and low (winter) photon flux. Following transfer of plants to solutions containing 1 millimolar Mn{sup 2+}, sequential samplings were made at various times for the following 9 days, during which Mn accumulation by leaves increased rapidly from {approx} 70 on day 0 to {approx} 1700 and {approx} 5000 microgram per gram dry matter after 1 and 9 days, respectively. In plants grown at high photon flux, net photosynthesis declined by {approx} 20 and {approx} 60% after 1 and 9 days, respectively, and the onset of this decline preceded appearance (after 3 to 4 days) of visible foliar symptoms of Mn toxicity. Intercellular CO{sub 2} concentrations and rates of transpiration were not significantly affected. Though the activity of latent or activated polyphenol oxidase increased in parallel with Mn accumulation, neither leaf respiration nor the activity of catalase (EC 1.11.1.6) and peroxidase (EC 1.10.1.7) were greatly affected. These effects from Mn toxicity could not be explained by any changes in protein or chlorophyll abundance. Additionally, they were not a consequence of Mn induced Fe deficiency. Therefore, inhibition of net photosynthesis and enhancement of polyphenol oxidase activity are early indicators of excess Mn accumulation in tobacco leaves.

  20. Pretreatment with alternation of light/dark periods improves the tolerance of tobacco (Nicotiana tabacum) to clomazone herbicide.

    PubMed

    Darwish, Majd; Lopez-Lauri, Félicie; El Maataoui, Mohamed; Urban, Laurent; Sallanon, Huguette

    2014-05-05

    This work analyses the effects of alternation of light/dark periods pretreatment (AL) in tobacco plantlets (Nicotiana tabacum L. cv.Virginie vk51) growing in solution with low concentration of the clomazone herbicide. The experimentation has been carried out by exposing the plantlets to successive and regulated periods of light (16min light/8min dark cycles, PAR 50μmolm(-2)s(-1)) for three days. The photosynthesis efficiency was determined by mean of the chlorophyll fluorescence and JIP-test. The AL pretreatment improved the clomazone tolerance; this has been observed by the increase in the leaf area of the plant, the maximal photochemical quantum efficiency of PSII (Fv/Fm), the actual PSII efficiency (ФPSII), the performance index (PIabs), the electron flux beyond Quinone A (1-VJ), and also by the diminution of the energy dissipating into heat (DI0/RC). Furthermore, AL pretreatment led to low accumulation of hydrogen peroxide (H2O2) which proves that the scavenging enzymatic system have been activated before clomazone treatment. In the plantlets pretreated with AL, with regard to the ascorbate content, some of antioxidant enzyme whose function is associated with it have continued to scavenge reactive oxygen species (ROS) induced by clomazone, such as ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDHAR) and glutathione reductase (GR). So, the observed photooxidative damages induced by clomazone herbicide were noticeably reduced.

  1. Oviposition by Spodoptera exigua on Nicotiana attenuata primes induced plant defence against larval herbivory.

    PubMed

    Bandoly, Michele; Hilker, Monika; Steppuhn, Anke

    2015-08-01

    Plants exhibit multifarious defence traits against herbivory that are constitutively expressed or induced upon attack. Insect egg deposition often precedes impending larval attack, and several plants can increase their resistance against larvae after experiencing the oviposition by an herbivore. The nature of such oviposition-mediated resistance remains unknown, and here we aim to determine plant traits that explain it. We test whether oviposition on a host plant can induce plant defence responses or enhance (prime) the induction of defence traits in response to larval herbivory. We exposed Nicotiana attenuata plants to oviposition by moths of a generalist herbivore, Spodoptera exigua. Its larvae suffered higher mortality, retarded development and inflicted less feeding damage on oviposition-experienced than on oviposition-unexperienced plants. While oviposition alone did not induce any of the examined defence traits, oviposited plants exhibited a stronger inducibility of known defence traits, i.e. caffeoylputrescine (CP) and trypsin protease inhibitors (TPIs). We found no effects of oviposition on phytohormone levels, but on the feeding-inducible accumulation of the transcription factor NaMyb8 that is governing biosynthesis of phenylpropanoid-polyamine conjugates, including CP. Comparison of larval performance on wild-type plants, CP-deficient plants (silenced NaMyb8 gene), and TPI-deficient plants (silenced NaPI gene) revealed that priming of plant resistance to larvae by prior oviposition required NaMyb8-mediated defence traits. Our results show that plants can use insect egg deposition as a warning signal to prime their feeding-induced defence.

  2. Functional interactions in the use of direct and indirect defences in native Nicotiana plants.

    PubMed

    Baldwin, I T

    1999-01-01

    Nicotiana attenuata has both direct (induced nicotine production) and indirect (induced release of mono- and sesquiterpenes) defences induced by herbivore attack; both are activated by the jasmonate cascade, albeit in different tissues (roots and shoots, respectively). The fact that both types of defences are induced suggests that their benefits are conditional. Indeed, jasmonate treatment of roots to induce nicotine production increases plant fitness correlates (lifetime viable seed production) when plants are grown in environments with herbivores, but decreases fitness when they are not. Because inducing nicotine production can make 6% of a plant's nitrogen budget unavailable for seed production, it can exact a resource-based cost. Volatile production is likely to be less costly but could make plants more 'apparent' to herbivores and thereby exact an ecological cost. Direct defences could also have ecological costs if they are sequestered by specialist herbivores and used against their enemies. Herbivory by the nicotine-tolerant herbivore Manduca sexta dramatically amplifies the increase in jasmonates and the quantity of volatiles released, but decreases the nicotine response in comparison to mechanical simulations of the wounding that larval feeding causes. The apparent switching from nicotine production to the release of volatiles may reflect incompatibilities in the use of direct and indirect defences with specialist herbivores.

  3. Heterologous expression of a rice miR395 gene in Nicotiana tabacum impairs sulfate homeostasis

    PubMed Central

    Yuan, Ning; Yuan, Shuangrong; Li, Zhigang; Li, Dayong; Hu, Qian; Luo, Hong

    2016-01-01

    Sulfur participates in many important mechanisms and pathways of plant development. The most common source of sulfur in soil –SO42−– is absorbed into root tissue and distributed into aerial part through vasculature system, where it is reduced into sulfite and finally sulfide within the subcellular organs such as chloroplasts and mitochondria and used for cysteine and methionine biosynthesis. MicroRNAs are involved in many regulation pathways by repressing the expression of their target genes. MiR395 family in Arabidopsis thaliana has been reported to be an important regulator involved in sulfate transport and assimilation, and a high-affinity sulphate transporter and three ATP sulfurylases (ATPS) were the target genes of AthmiR395 (Arabidopsis thaliana miR395). We have cloned a miR395 gene from rice (Oryza sativa) and studied its function in plant nutritional response. Our results indicated that in rice, transcript level of OsamiR395 (Oryza sativa miR395) increased under sulfate deficiency conditions, and the two predicted target genes of miR395 were down-regulated under the same conditions. Overexpression of OsamiR395h in tobacco impaired its sulfate homeostasis, and sulfate distribution was also slightly impacted among leaves of different ages. One sulfate transporter (SULTR) gene NtaSULTR2 was identified to be the target of miR395 in Nicotiana tobacum, which belongs to low affinity sulfate transporter group. Both miR395 and NtaSULTR2 respond to sulfate starvation in tobacco. PMID:27350219

  4. Induction of UDP-glucose:salicylic acid glucosyltransferase activity in tobacco mosaic virus-inoculated tobacco (Nicotiana tabacum) leaves

    SciTech Connect

    Enyedi, A.J.; Raskin, I. )

    1993-04-01

    Salicylic acid (SA) is a putative signal that activates plant resistance to pathogens. SA levels increase systemically following the hypersensitive response produced by tobacco masaic virus (TMV) inoculation of tobacco (Nicotiana tabacum L. cv Xanthi-nc) leaves. The SA increase in the inoculated leaf coincided with the appearance of a [beta]-glucosidase-hydrolyzable SA conjugate identified as [beta]-O-D-glucosylsalicylic acid (GSA). SA and GSA accumulation in the TMV-inoculated leaf paralleled the increase in the activity of a UDP-glucose:salicylic acid 3-O-glucosyltransferase (EC 2.4.1.35) ([beta]-GTase) capable of converting SA to GSA. Healthy tissues had constitutive [beta]-GTase activity of 0.076 milliunits g[sup [minus]1] fresh weight. This activity started to increase 48 h after TMV inoculation, reaching its maximum (6.7-fold induction over the basal levels) 72 h after TMV inoculation. No significant GSA or elevated [beta]-GTase activity could be detected in the healthy leaf immediately above the TMV-inoculated leaf. The effect of TMV inoculation on the [beta]-GTase and GSA accumulation could be duplicated by infiltrating tobacco leaf discs with SA at the levels naturally produced in TMV-inoculated leaves (2.7--27.0 [mu]g g[sup [minus]1] fresh weight). Pretreatment of leaf discs with the protein synthesis inhibitor cycloheximide inhibited the induction of [beta]GTase by SA and prevented the formation of GSA. Of 12 analogs of SA tested, only 2,6-dihydroxybenzoic acid induced [beta]-GTase activity. 21 refs., 5 figs.

  5. Bensulfuron-Methyl Treatment of Soil Affects the Infestation of Whitefly, Aphid, and Tobacco Mosaic Virus on Nicotiana tabacum

    PubMed Central

    Li, Renyi; Islam, Saif Ul; Wu, Zujian; Ye, Xiujuan

    2016-01-01

    Bensulfuron-methyl (BSM) is widely used in paddy soil for weed control. BSM residue in the soil has been known to inhibit the growth of sensitive crop plants. However, it is unknown whether BSM residue can affect the agrosystem in general. In this study, we have found significant effects of BSM on the infestation of Bemisia tabaci, Myzus persicae, and Tobacco mosaic virus (TMV) in Nicotiana tabacum. The soil was treated with BSM before the pest inoculation. The herbicide-treated tobaccos showed resistance to B. tabaci, but this resistance could not be detected until 15-day post-infestation when smaller number of adults B. tabaci appeared. In M. persicae assay, the longevity of all development stages of insects, and the fecundity of insects were not significantly affected when feeding on BSM-treated plants. In TMV assay, the BSM treatment also reduced virus-induced lesions in early infection time. However, the titer of TMV in BSM treated plants increased greatly over time and was over 40-fold higher than the mock-infected control plants after 20 days. Further studies showed that BSM treatment increased both jasmonic acid (JA) and salicylic acid (SA) levels in tobacco, as well as the expression of target genes in the JA and SA signaling pathways, such as NtWIPK, NtPR1a, and NtPAL. NtPR1a and NtPAL were initially suppressed after virus-inoculation, while NtRDR1 and NtRDR6, which play a key role in fighting virus infection, only showed up- or were down-regulated 20 days post virus-inoculation. Taken together, our results suggested that BSM residue in the soil may affect the metabolism of important phytohormones such as JA and SA in sensitive plants and consequently affect the plant immune response against infections such as whitefly, aphids, and viruses. PMID:28083007

  6. Three nicotine demethylase genes mediate nornicotine biosynthesis in Nicotiana tabacum L.: functional characterization of the CYP82E10 gene.

    PubMed

    Lewis, Ramsey S; Bowen, Steven W; Keogh, Matthew R; Dewey, Ralph E

    2010-12-01

    In most tobacco (Nicotiana tabacum L.) plants, nornicotine is a relatively minor alkaloid, comprising about 2-5% of the total pyridine alkaloid pool in the mature leaf. Changes in gene expression at an unstable locus, however, can give rise to plants that produce high levels of nornicotine, specifically during leaf senescence and curing. Minimizing the nornicotine content in tobacco is highly desirable, because this compound serves as the direct precursor in the synthesis of N'-nitrosonornicotine, a potent carcinogen in laboratory animals. Nornicotine is likely produced almost entirely via the N-demethylation of nicotine, in a process called nicotine conversion that is catalyzed by the enzyme nicotine N-demethylase (NND). Previous studies have identified CYP82E4 as the specific NND gene responsible for the unstable conversion phenomenon, and CYP82E5v2 as a putative minor NND gene. Here, by discovery and characterization of CYP82E10, a tobacco NND gene, is reported. PCR amplification studies showed that CYP82E10 originated from the N. sylvestris ancestral parent of modern tobacco. Using a chemical mutagenesis strategy, knockout mutations were induced and identified in all three tobacco NND genes. By generating a series of mutant NND genotypes, the relative contribution of each NND gene toward the nornicotine content of the plant was assessed. Plants possessing knockout mutations in all three genes displayed nornicotine phenotypes that were much lower (∼0.5% of total alkaloid content) than that found in conventional tobacco cultivars. The introduction of these mutations into commercial breeding lines promises to be a viable strategy for reducing the levels of one of the best characterized animal carcinogens found in tobacco products.

  7. Comparative study on macro- and micro-elements concentration in Nicotiana tabacum and Faba siliquis plants by ICP-MS

    NASA Astrophysics Data System (ADS)

    Balazs, Zoltan; Voica, Cezara; Dehelean, Adriana; Magdas, Dana Alina; Ristoiu, Dumitru

    2015-12-01

    Plants are important components of ecosystems as they transfer elements from abiotic into biotic environments. The concentration of macro and micro-elements in tobacco leaves (Nicotiana tabacum) and bean (Faba siliquis) was analyzed using ICP-MS technique. The results obtained indicated that the mean concentration of Mg, P, K and Ca in tobacco leaves was 0.965, 0.812, 4.412 and 2.694 g.kg-1, respectively, while in bean samples were 0.899, 2.024, 6.725 and 1.387 g.kg-1, respectively. Mn concentration ranged from 156.835 mg.kg-1 to 234.593 mg.kg-1 in tobacco leaves and from 116.174 mg.kg-1 to 440.423 mg.kg-1 in bean samples. The results for Cu and Zn were between 7.262 mg.kg-1 and 105.738 mg.kg-1, 68.549 mg.kg-1 and 113.720 mg.kg-1 (tobacco leaves); and 6.830 mg.kg-1 and 46.034 mg.kg-1, 50.166 mg.kg-1 and 77.242 mg.kg-1 (bean samples), respectively. In analyzed samples, Pb, Cd and As concentrations ranged between <0.001-0.717 mg.kg-1, 0.046 mg.kg-1 -6.218 mg.kg-1, <0.001-0.381 mg.kg-1. The paper discusses the transfer of metal ions (Mn, As, Cd, Cu, Pb and Zn, respectively) from soil to these plants in terms of transfer factors (TF).

  8. Multi-Platform Metabolomic Analyses of Ergosterol-Induced Dynamic Changes in Nicotiana tabacum Cells

    PubMed Central

    Tugizimana, Fidele; Steenkamp, Paul A.; Piater, Lizelle A.; Dubery, Ian A.

    2014-01-01

    Metabolomics is providing new dimensions into understanding the intracellular adaptive responses in plants to external stimuli. In this study, a multi-technology-metabolomic approach was used to investigate the effect of the fungal sterol, ergosterol, on the metabolome of cultured tobacco cells. Cell suspensions were treated with different concentrations (0–1000 nM) of ergosterol and incubated for different time periods (0–24 h). Intracellular metabolites were extracted with two methods: a selective dispersive liquid-liquid micro-extraction and a general methanol extraction. Chromatographic techniques (GC-FID, GC-MS, GC×GC-TOF-MS, UHPLC-MS) and 1H NMR spectroscopy were used for quantitative and qualitative analyses. Multivariate data analyses (PCA and OPLS-DA models) were used to extract interpretable information from the multidimensional data generated from the analytical techniques. The results showed that ergosterol triggered differential changes in the metabolome of the cells, leading to variation in the biosynthesis of secondary metabolites. PCA scores plots revealed dose- and time-dependent metabolic variations, with optimal treatment conditions being found to be 300 nM ergosterol and an 18 h incubation period. The observed ergosterol-induced metabolic changes were correlated with changes in defence-related metabolites. The ‘defensome’ involved increases in terpenoid metabolites with five antimicrobial compounds (the bicyclic sesquiterpenoid phytoalexins: phytuberin, solavetivone, capsidiol, lubimin and rishitin) and other metabolites (abscisic acid and phytosterols) putatively identified. In addition, various phenylpropanoid precursors, cinnamic acid derivatives and - conjugates, coumarins and lignin monomers were annotated. These annotated metabolites revealed a dynamic reprogramming of metabolic networks that are functionally correlated, with a high complexity in their regulation. PMID:24498209

  9. Properties of tobacco (Nicotiana tabacum) cadmium-binding peptide(s). Unique non-metallothionein cadmium ligands.

    PubMed Central

    Reese, R N; Wagner, G J

    1987-01-01

    The chemical and physical characteristics of Cd-binding peptides isolated from tobacco (Nicotiana tabacum) leaves and suspension-cultured tobacco cells were determined and compared with properties of rat liver Cd,Zn-thionein. Some emphasis was placed on metal-binding and specificity properties. Cd-peptides of apparent Mr 6000 and 2000 were induced in tobacco leaves by growth of plants with 90 microM-Cd. Only the apparent-Mr-2000 Cd-peptide was induced in the leaves of tobacco plants grown in the presence of 3 microM-Cd. In cultured tobacco cells exposed to a wide range of Cd levels (3-180 microM), a peptide of apparent Mr 2000 was observed. Under denaturing conditions [6 M-guanidinium chloride (GdmCl) with or without 100 mM-2-mercaptoethanol], all of the above forms were shown to have an Mr of approx. 1300, compared with an Mr of 6000 for Cd,Zn-thionein. The apparent disaggregation of the Mr-6000 form by GdmCl to what appears to be the unit Cd-binding peptide was reversible. Tobacco-derived Cd-peptide contained approx. 40, 35 and 15 residues of glutamate/glutamine, cysteine and glycine respectively, with serine, lysine, and aromatic residues being absent. Tobacco Cd-peptide had an isoelectric point (pI) of 3.15, which is lower than the pI greater than or equal to 4 reported for metallothionein. A 50% dissociation of Cd occurred at pH 5 and 3.5 for the tobacco Cd-peptide and Cd,Zn-thionein respectively, and GdmCl was shown to cause Cd dissociation from tobacco peptide, but not from metallothionein. No evidence was obtained for Zn induction in vivo of, or Zn binding in vitro to, tobacco Cd-peptide. Copper induced a low-Mr metal-binding component in cultured tobacco cells which did not appear to be identical with the peptide induced by Cd. Properties of tobacco Cd-peptide and Cd,Zn-thionein, including metal affinity and selectivity, are greatly different, except for the common presence of 30 residues of cysteine/100 residues. PMID:3593213

  10. Drought stress alters water relations and expression of PIP-type aquaporin genes in Nicotiana tabacum plants.

    PubMed

    Mahdieh, Majid; Mostajeran, Akbar; Horie, Tomoaki; Katsuhara, Maki

    2008-05-01

    Plasma membrane intrinsic proteins (PIPs), a type of aquaporins, mediate water transport in many plant species. In this study, we investigated the relationship between the functions of PIP-type water channels and water relations of tobacco plants (Nicotiana tabacum cv. Samsun) under drought stress. Drought stress treatments have led to reductions in the stomatal conductance, transpiration, water potential and turgor pressure in leaves, and also the sap flow rate and osmotic hydraulic conductance in roots. In contrast, leaf osmotic pressure was increased in response to drought stress. Interestingly, the accumulation of NtPIP1;1 and NtPIP2;1 transcripts was significantly decreased, but only that of the NtAQP1 transcript was increased under drought stress. Functional analysis using Xenopus laevis oocytes revealed that NtPIP2;1 shows marked water transport activity, but the activities of NtAQP1 and NtPIP1;1 are weak or almost negligible, respectively, when expressed alone. However, co-expression of NtPIP1;1 with NtPIP2;1 significantly enhanced water transport activity compared with that of NtPIP1;1- or NtPIP2;1-expressing oocytes, suggesting that these two aquaporins may function as a water channel, forming a heterotetramer. Heteromerization of NtPIP1;1 and NtPIP2;1 was also suggested by co-expression analyses of NtPIP1;1-GFP (green fluorescent protein) and NtPIP2;1 in Xenopus oocytes. Re-watering treatments recovered water relation parameters and the accumulation of the three NtPIP transcripts to levels similar to control conditions. These results suggest that NtPIP1;1 and NtPIP2;1 play an important role in water transport in roots, and that expression of NtPIP1;1 and NtPIP2;1 is down-regulated in order to reduce osmotic hydraulic conductance in the roots of tobacco plants under drought stress.

  11. Root-specific expression of opine genes and opine accumulation in some cultivars of the naturally occurring genetically modified organism Nicotiana tabacum.

    PubMed

    Chen, Ke; de Borne, François Dorlhac; Julio, Emilie; Obszynski, Julie; Pale, Patrick; Otten, Léon

    2016-08-01

    Previous studies have shown that Nicotiana tabacum contains three Agrobacterium-derived T-DNA sequences inherited from its paternal ancestor Nicotiana tomentosiformis. Among these, the TB locus carries an intact mannopine synthase 2' gene (TB-mas2'). This gene is similar to the Agrobacterium rhizogenes A4-mas2' gene that encodes the synthesis of the Amadori compound deoxyfructosyl-glutamine (DFG or santhopine). In this study we show that TB-mas2' is expressed at very low levels in N. tomentosiformis and in most N. tabacum cultivars; however, some cultivars show high TB-mas2' expression levels. The TB-mas2' promoter sequences of low- and high-expressing cultivars are identical. The low/high level of expression segregates as a single Mendelian factor in a cross between a low- and a high-expression cultivar. pTB-mas2'-GUS and pA4-mas2'-GUS reporter genes were stably introduced in N. benthamiana. Both were mainly expressed in the root expansion zone and leaf vasculature. Roots of tobacco cultivars with high TB-mas2' expression contain detectable levels of DFG.

  12. Effect of UV irradiation, toluidine blue, and environment on maternal haploid frequencies from the cross between Nicotiana tabacum and N. africana

    SciTech Connect

    Chimoyo, H.M.

    1988-01-01

    Treating Nicotiana africana Merxm. pollen with three levels UV radiation prior to pollinating four cultivars of flue-cured tobacco (Coker 176, NC95, McN944 and PD4), Nicotiana tabacum produced 1,953 viable seedlings from an estimated total of 170,248 seeds, of which 1,667 were haploid and 286 were hybrids. Drenching N. tabacum flowers with toluidine blue 18 hours after pollination with normal N. africana pollen, yielded 511 viable seedlings from 70,613 seeds, of which 346 were haploid and 165 hybrids. Untreated pollen gave 548 viable seedlings from 56,291 seeds, comprising 341 haploids and 208 hybrids. Contrary to results from a previous histological study, in vivo pollen tube growth rate appears to be similar irrespective of pollen source or treatment, and fertilization seems to occur at about the same time as in the selfed control. From an estimated total of 803,854 seeds sown, 3,014 viable seedlings were obtained. Coker 176 gave significantly higher yields of haploids than the other three cultivars. Field grown plants produced more haploids than greenhouse grown plants. Further evidence was obtained to support selective chromosomal elimination as the mechanism governing the development of maternal haploids from this interspecific cross.

  13. Acidic α-galactosidase is the most abundant nectarin in floral nectar of common tobacco (Nicotiana tabacum)

    PubMed Central

    Zha, Hong-Guang; Flowers, V. Lynn; Yang, Min; Chen, Ling-Yang; Sun, Hang

    2012-01-01

    Background and Aims To date, most floral nectarins (nectar proteins) are reported to function in nectar defence, particularly for insect-pollinated outcrossing species. We compared nectarin composition and abundance in selfing common tobacco (Nicotiana tobaccum) with outcrossing ornamental tobacco plants to elucidate the functional difference of nectarins in different reproductive systems. Methods Common tobacco (CT) nectarins were separated by SDS-PAGE and the N terminus of the most abundant nectarin was sequenced via Edman degradation. The full-length nectarin gene was amplified and cloned from genomic DNA and mRNA with hiTail-PCR and RACE (rapid amplification of cDNA ends), and expression patterns were then investigated in different tissues using semi-quantitative reverse transcriptase PCR. Additionally, high-performance liquid chromatography and enzymatic analyses of nectar sugar composition, and other biochemical traits and functions of the novel nectarin were studied. Key Results The most abundant nectarin in CT nectar is an acidic α-galactosidase, here designated NTα-Gal. This compound has a molecular mass of 40 013 Da and a theoretical pI of 5·33. NTα-Gal has a conserved α-Gal characteristic signature, encodes a mature protein of 364 amino acids and is expressed in different organs. Compared with 27 other melliferous plant species from different families, CT floral nectar demonstrated the highest α-Gal activity, which is inhibited by d-galactose. Raffinose family oligosaccharides were not detected in CT nectar, indicating that NTα-Gal does not function in post-secretory hydrolysis. Moreover, tobacco plant fruits did not develop intact skin with galactose inhibition of NTα-Gal activity in nectar, suggesting that NTα-Gal induces cell-wall surface restructuring during the initial stages of fruit development. Conclusions α-Gal was the most abundant nectarin in selfing CT plants, but was not detected in the nectar of strictly outcrossing sister tobacco

  14. The transmitting tissue of Nicotiana tabacum is not essential to pollen tube growth, and its ablation can reverse prezygotic interspecific barriers.

    PubMed

    Smith, Alan G; Eberle, Carrie A; Moss, Nicole G; Anderson, Neil O; Clasen, Benjamin M; Hegeman, Adrian D

    2013-12-01

    The Nicotiana tabacum transmitting tissue is a highly specialized file of metabolically active cells that is the pathway for pollen tubes from the stigma to the ovules where fertilization occurs. It is thought to be essential to pollen tube growth because of the nutrients and guidance it provides to the pollen tubes. It also regulates gametophytic self-incompatibility in the style. To test the function of the transmitting tissue in pollen tube growth and to determine its role in regulating prezygotic interspecific incompatibility, genetic ablation was used to eliminate the mature transmitting tissue, producing a hollow style. Despite the absence of the mature transmitting tissue and greatly reduced transmitting-tissue-specific gene expression, self-pollen tubes had growth to the end of the style. Pollen tubes grew at a slower rate in the transmitting-tissue-ablated line during the first 24 h post-pollination. However, pollen tubes grew to a similar length 40 h post-pollination with and without a transmitting tissue. Ablation of the N. tabacum transmitting tissue significantly altered interspecific pollen tube growth. These results implicate the N. tabacum transmitting tissue in facilitating or inhibiting interspecific pollen tube growth in a species-dependent manner and in controlling prezygotic reproductive barriers.

  15. Posttranslational processing of a new class of hydroxyproline-containing proteins. Prolyl hydroxylation and C-terminal cleavage of tobacco (Nicotiana tabacum) vacuolar chitinase.

    PubMed

    Sticher, L; Hofsteenge, J; Neuhaus, J M; Boller, T; Meins, F

    1993-04-01

    The fungicidal class I chitinases (EC 3.2.1.14) are believed to be important in defending plants against microbial pathogens. The vacuolar isoforms of tobacco (Nicotiana tabacum), chitinases A and B, are the first examples of a new type of hydroxyproline-containing protein with intracellular location, enzymic activity, and a small number of hydroxyprolyl residues restricted to a single, short peptide sequence. We have investigated the posttranslational processing and intracellular transport of transgene-encoded chitinase A in callus cultures of Nicotiana tabacum L. cv Havana 425 and leaves of Nicotiana sylvestris Spegazzini and Comes. Pulse-chase experiments and cell fractionation show that chitinase A is processed in two distinct steps. In the first step, the nascent protein undergoes an increase in apparent M(r) of approximately 1500 detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Experiments with the inhibitor of prolyl hydroxylation, alpha,alpha'-dipyridyl, and pulse-chase labeling of cells expressing recombinant forms of chitinase A indicate that the anomalous increase in M(r) is due to hydroxylation of prolyl residues. This step occurs in the endomembrane system before sorting for secretion and vacuolar transport and does not appear to be required for correct targeting of chitinase A to the vacuole. The second step is a proteolytic cleavage. Sequencing of tryptic peptides of the mature proteins indicates that during processing essentially all molecules of chitinase A and B lose a C-terminal heptapeptide, which has been shown to be a vacuolar targeting signal. This appears to occur primarily in the endomembrane system late in intracellular transport. A model for the posttranslational modification of chitinase A is proposed.

  16. Improvement in the stability and functionality of Nicotiana tabacum produced recombinant TRAIL through employment of endoplasmic reticulum expression and ascorbate buffer mediated extraction strategies

    PubMed Central

    Heidari, Hamid Reza; Bandehpour, Mojgan; Vahidi, Hossein; Barar, Jaleh; Kazemi, Bahram; Naderi-Manesh, Hossein

    2014-01-01

    Introduction: In order to employ Nicotiana tabacum cells as a profitable natural bioreactor for production of bio-functional "Soluble human TRAIL" (ShTRAIL), endoplasmic reticulum (ER) targeted expression and innovative extraction procedures were exploited. Methods: At first, the ShTRAIL encoding gene was sub-cloned into designed H2 helper vector to equip it with potent TMV omega leader sequences, ER sorting signal peptide, poly-histidine tag and ER retention signal peptide (KDEL). Then, the ER targeted ShTRAIL cassette was sequentially sub-cloned into "CaMV-35S" helper and "pGreen-0179" final expression vectors. Afterward, Agrobacterium mediated transformation method was adopted to express the ShTRAIL in the ER of N. tabacum . Next, the ShTRAIL protein was extracted through both phosphate and innovative ascorbate extraction buffers. Subsequently, oligomerization state of the ShTRAIL was evaluated through cross-linking assay and western blot analysis. Then, semi-quantitative western blot analysis was performed to estimate the ShTRAIL production. Finally, biological activity of the ShTRAIL was evaluated through MTT assay. Results: The phosphate buffer extracted ShTRAIL was produced in dimmer form, whereas the ShTRAIL extracted with ascorbate buffer generated trimer form. The ER targeted ShTRAIL strategy increased the ShTRAIL’s production level up to about 20 μg/g of fresh weight of N. tabacum . MTT assay indicated that ascorbate buffer extracted ShTRAIL could prohibit proliferation of A549 cell line. Conclusion: Endoplasmic reticulum expression and reductive ascorbate buffer extraction procedure can be employed to enhance the stability and overall production level of bio-functional recombinant ShTRAIL from transgenic N. tabacum cells. PMID:25337465

  17. Spectral reflectance, chlorophyll fluorescence and virological investigations of tobacco plants (Nicotiana tabacum L.) infected with Tobacco mosaic virus (TMV)

    NASA Astrophysics Data System (ADS)

    Krezhova, Dora; Hristova, Dimitrina; Iliev, Ilko; Yanev, Tony

    Application of multispectral remote sensing techniques to plant condition monitoring has been adopted for various purposes. Remote sensing is a reliable tool for detecting signs of vege-tation stress and diseases. Spectral reflectance and chlorophyll fluorescence are functions of tissue optical properties and biological status of the plants, and illumination conditions. The mean reflectance spectrum depends on the relative composition of all the pigments in the leaf including chlorophylls, carotenoids etc. Chlorophyll fluorescence results from the primary re-actions of photosynthesis and during the last decade it finds widening application as a means for revelation of stress and diseases. The changes in chlorophyll function take place before the alteration in chlorophyll content to occur so that changes in the fluorescence signal arise before any visible signs are apparent. The aim of our investigations was to study the development and spreading out of a viral infection on the leaves of two cultivars tobacco plants (Nicotiana tabacum L.) infected with Tobacco mosaic virus (TMV). We applied two remote sensing tech-niques (spectral reflectance and chlorophyll fluorescence measurements) for evaluation of the changes in the optical properties of the plants in accordance to their physiological status. The serological analyses via the Double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) were made with appropriate kits (Leowe, Germany) for quantitative assessment of the concentration of viruses in the plants. The tobacco plants were grown in green house under controlled conditions. The first cultivar Nevrocop 1146 is known as resistive to the TMV, i.e. it shows hypersensitive response. The second cultivar named Krumovgrad is normally sen-sitive to the TMV. At growth stage 4-6 expanded leaf, up to one leaf from 20 plants for each cultivar were inoculated with TMV. The leaves opposite to the infected ones formed the group of control (untreated) leaves. The

  18. Molecular cloning and functional characterization of the lycopene ε-cyclase gene via virus-induced gene silencing and its expression pattern in Nicotiana tabacum.

    PubMed

    Shi, Yanmei; Wang, Ran; Luo, Zhaopeng; Jin, Lifeng; Liu, Pingping; Chen, Qiansi; Li, Zefeng; Li, Feng; Wei, Chunyang; Wu, Mingzhu; Wei, Pan; Xie, He; Qu, Lingbo; Lin, Fucheng; Yang, Jun

    2014-08-22

    Lycopene ε-cyclase (ε-LCY) is a key enzyme that catalyzes the synthesis of α-branch carotenoids through the cyclization of lycopene. Two cDNA molecules encoding ε-LCY (designated Ntε-LCY1 and Ntε-LCY2) were cloned from Nicotiana tabacum. Ntε-LCY1 and Ntε-LCY2 are encoded by two distinct genes with different evolutionary origins, one originating from the tobacco progenitor, Nicotiana sylvestris, and the other originating from Nicotiana tomentosiformis. The two coding regions are 97% identical at the nucleotide level and 95% identical at the amino acid level. Transcripts of Ntε-LCY were detectable in both vegetative and reproductive organs, with a relatively higher level of expression in leaves than in other tissues. Subcellular localization experiments using an Ntε-LCY1-GFP fusion protein demonstrated that mature Ntε-LCY1 protein is localized within the chloroplast in Bright Yellow 2 suspension cells. Under low-temperature and low-irradiation stress, Ntε-LCY transcript levels substantially increased relative to control plants. Tobacco rattle virus (TRV)-mediated silencing of ε-LCY in Nicotiana benthamiana resulted in an increase of β-branch carotenoids and a reduction in the levels of α-branch carotenoids. Meanwhile, transcripts of related genes in the carotenoid biosynthetic pathway observably increased, with the exception of β-OHase in the TRV-ε-lcy line. Suppression of ε-LCY expression was also found to alleviate photoinhibition of Potosystem II in virus-induced gene silencing (VIGS) plants under low-temperature and low-irradiation stress. Our results provide insight into the regulatory role of ε-LCY in plant carotenoid biosynthesis and suggest a role for ε-LCY in positively modulating low temperature stress responses.

  19. Molecular Cloning and Functional Characterization of the Lycopene ε-Cyclase Gene via Virus-Induced Gene Silencing and Its Expression Pattern in Nicotiana tabacum

    PubMed Central

    Shi, Yanmei; Wang, Ran; Luo, Zhaopeng; Jin, Lifeng; Liu, Pingping; Chen, Qiansi; Li, Zefeng; Li, Feng; Wei, Chunyang; Wu, Mingzhu; Wei, Pan; Xie, He; Qu, Lingbo; Lin, Fucheng; Yang, Jun

    2014-01-01

    Lycopene ε-cyclase (ε-LCY) is a key enzyme that catalyzes the synthesis of α-branch carotenoids through the cyclization of lycopene. Two cDNA molecules encoding ε-LCY (designated Ntε-LCY1 and Ntε-LCY2) were cloned from Nicotiana tabacum. Ntε-LCY1 and Ntε-LCY2 are encoded by two distinct genes with different evolutionary origins, one originating from the tobacco progenitor, Nicotiana sylvestris, and the other originating from Nicotiana tomentosiformis. The two coding regions are 97% identical at the nucleotide level and 95% identical at the amino acid level. Transcripts of Ntε-LCY were detectable in both vegetative and reproductive organs, with a relatively higher level of expression in leaves than in other tissues. Subcellular localization experiments using an Ntε-LCY1-GFP fusion protein demonstrated that mature Ntε-LCY1 protein is localized within the chloroplast in Bright Yellow 2 suspension cells. Under low-temperature and low-irradiation stress, Ntε-LCY transcript levels substantially increased relative to control plants. Tobacco rattle virus (TRV)-mediated silencing of ε-LCY in Nicotiana benthamiana resulted in an increase of β-branch carotenoids and a reduction in the levels of α-branch carotenoids. Meanwhile, transcripts of related genes in the carotenoid biosynthetic pathway observably increased, with the exception of β-OHase in the TRV-ε-lcy line. Suppression of ε-LCY expression was also found to alleviate photoinhibition of Potosystem II in virus-induced gene silencing (VIGS) plants under low-temperature and low-irradiation stress. Our results provide insight into the regulatory role of ε-LCY in plant carotenoid biosynthesis and suggest a role for ε-LCY in positively modulating low temperature stress responses. PMID:25153631

  20. Uptake of NO, NO 2 and O 3 by sunflower ( Helianthus annuus L.) and tobacco plants ( Nicotiana tabacum L.): dependence on stomatal conductivity

    NASA Astrophysics Data System (ADS)

    Neubert, A.; Kley, D.; Wildt, J.; Segschneider, H. J.; Förstel, H.

    The uptake of NO, NO 2 and O 3 by sunflowers ( Helianthus annuus L. var. giganteus) and tobacco plants ( Nicotiana tabacum L. var. Bel W3), using concentrations representative for moderately polluted air, has been determined by gas exchange experiments. Conductivities for these trace gases were measured at different light fluxes ranging from 820 μEm -2s -1 to darkness. The conductivities to water vapor and the trace gases are highly correlated. It is concluded that the uptake of NO, NO 2 and O 3 by sunflowers and tobacco plants is linearly dependent on stomatal opening. While the uptake of NO is limited by the mesophyll resistance, the uptake of NO 2 is only by diffusion through the stomata. Loss processes by deposition to the leaf surfaces are more pronounced for O 3 than for NO and NO 2.

  1. Jasmonate-Sensitivity-Assisted Screening and Characterization of Nicotine Synthetic Mutants from Activation-Tagged Population of Tobacco (Nicotiana tabacum L.)

    PubMed Central

    Yin, Guoying; Wang, Wenjing; Niu, Haixia; Ding, Yongqiang; Zhang, Dingyu; Zhang, Jie; Liu, Guanshan; Wang, Sangen; Zhang, Hongbo

    2017-01-01

    Nicotine is a secondary metabolite that is important to the defense system and commercial quality of tobacco (Nicotiana tabacum L.). Jasmonate and its derivatives (JAs) are phytohormone regulators of nicotine formation; however, the underlying molecular mechanism of this process remains largely unclear. Owing to the amphitetraploid origin of N. tabacum, research on screening and identification of nicotine-synthetic mutants is relatively scarce. Here, we describe a method based on JA-sensitivity for screening nicotine mutants from an activation-tagged population of tobacco. In this approach, the mutants were first screened for abnormal JA responses in seed germination and root elongation, and then the levels of nicotine synthesis and expression of nicotine synthetic genes in the mutants with altered JA-response were measured to determine the nicotine-synthetic mutants. We successfully obtained five mutants that maintained stable nicotine contents and JA responses for three generations. This method is simple, effective and low-cost, and the finding of transcriptional changes of nicotine synthetic genes in the mutants shows potentials for identifying novel regulators involved in JA-regulated nicotine biosynthesis. PMID:28243248

  2. Jasmonate-Sensitivity-Assisted Screening and Characterization of Nicotine Synthetic Mutants from Activation-Tagged Population of Tobacco (Nicotiana tabacum L.).

    PubMed

    Yin, Guoying; Wang, Wenjing; Niu, Haixia; Ding, Yongqiang; Zhang, Dingyu; Zhang, Jie; Liu, Guanshan; Wang, Sangen; Zhang, Hongbo

    2017-01-01

    Nicotine is a secondary metabolite that is important to the defense system and commercial quality of tobacco (Nicotiana tabacum L.). Jasmonate and its derivatives (JAs) are phytohormone regulators of nicotine formation; however, the underlying molecular mechanism of this process remains largely unclear. Owing to the amphitetraploid origin of N. tabacum, research on screening and identification of nicotine-synthetic mutants is relatively scarce. Here, we describe a method based on JA-sensitivity for screening nicotine mutants from an activation-tagged population of tobacco. In this approach, the mutants were first screened for abnormal JA responses in seed germination and root elongation, and then the levels of nicotine synthesis and expression of nicotine synthetic genes in the mutants with altered JA-response were measured to determine the nicotine-synthetic mutants. We successfully obtained five mutants that maintained stable nicotine contents and JA responses for three generations. This method is simple, effective and low-cost, and the finding of transcriptional changes of nicotine synthetic genes in the mutants shows potentials for identifying novel regulators involved in JA-regulated nicotine biosynthesis.

  3. Two aspartate residues at the putative p10 subunit of a type II metacaspase from Nicotiana tabacum L. may contribute to the substrate-binding pocket.

    PubMed

    Acosta-Maspons, Alexis; Sepúlveda-García, Edgar; Sánchez-Baldoquín, Laura; Marrero-Gutiérrez, Junier; Pons, Tirso; Rocha-Sosa, Mario; González, Lien

    2014-01-01

    Metacaspases are cysteine proteases present in plants, fungi, prokaryotes, and early branching eukaryotes, although a detailed description of their cellular function remains unclear. Currently, three-dimensional (3D) structures are only available for two metacaspases: Trypanosoma brucei (MCA2) and Saccharomyces cerevisiae (Yca1). Furthermore, metacaspases diverged from animal caspases of known structure, which limits straightforward homology-based interpretation of functional data. We report for the first time the identification and initial characterization of a metacaspase of Nicotiana tabacum L., NtMC1. By combining domain search, multiple sequence alignment (MSA), and protein fold-recognition studies, we provide compelling evidences that NtMC1 is a plant metacaspase type II, and predict its 3D structure using the crystal structure of two type I metacaspases (MCA2 and Yca1) and Gsu0716 protein from Geobacter sulfurreducens as template. Analysis of the predicted 3D structure allows us to propose Asp353, at the putative p10 subunit, as a new member of the aspartic acid triad that coordinates the P1 arginine/lysine residue of the substrate. Nevertheless, site-directed mutagenesis and expression analysis in bacteria and Nicotiana benthamiana indicate the functionality of both Asp348 and Asp353. Through the co-expression of mutant and wild-type proteins by transient expression in N. benthamiana leaves we found that polypeptide processing seems to be intramolecular. Our results provide the first evidence in plant metacaspases concerning the functionality of the putative p10 subunit.

  4. Transfer of the cytochrome P450-dependent dhurrin pathway from Sorghum bicolor into Nicotiana tabacum chloroplasts for light-driven synthesis

    PubMed Central

    Gnanasekaran, Thiyagarajan; Karcher, Daniel; Nielsen, Agnieszka Zygadlo; Martens, Helle Juel; Ruf, Stephanie; Kroop, Xenia; Olsen, Carl Erik; Motawie, Mohammed Saddik; Pribil, Mathias; Møller, Birger Lindberg; Bock, Ralph; Jensen, Poul Erik

    2016-01-01

    Plant chloroplasts are light-driven cell factories that have great potential to act as a chassis for metabolic engineering applications. Using plant chloroplasts, we demonstrate how photosynthetic reducing power can drive a metabolic pathway to synthesise a bio-active natural product. For this purpose, we stably engineered the dhurrin pathway from Sorghum bicolor into the chloroplasts of Nicotiana tabacum (tobacco). Dhurrin is a cyanogenic glucoside and its synthesis from the amino acid tyrosine is catalysed by two membrane-bound cytochrome P450 enzymes (CYP79A1 and CYP71E1) and a soluble glucosyltransferase (UGT85B1), and is dependent on electron transfer from a P450 oxidoreductase. The entire pathway was introduced into the chloroplast by integrating CYP79A1, CYP71E1, and UGT85B1 into a neutral site of the N. tabacum chloroplast genome. The two P450s and the UGT85B1 were functional when expressed in the chloroplasts and converted endogenous tyrosine into dhurrin using electrons derived directly from the photosynthetic electron transport chain, without the need for the presence of an NADPH-dependent P450 oxidoreductase. The dhurrin produced in the engineered plants amounted to 0.1–0.2% of leaf dry weight compared to 6% in sorghum. The results obtained pave the way for plant P450s involved in the synthesis of economically important compounds to be engineered into the thylakoid membrane of chloroplasts, and demonstrate that their full catalytic cycle can be driven directly by photosynthesis-derived electrons. PMID:26969746

  5. Involvement of the Leaf-Specific Multidrug and Toxic Compound Extrusion (MATE) Transporter Nt-JAT2 in Vacuolar Sequestration of Nicotine in Nicotiana tabacum

    PubMed Central

    Shitan, Nobukazu; Minami, Shota; Morita, Masahiko; Hayashida, Minaho; Ito, Shingo; Takanashi, Kojiro; Omote, Hiroshi; Moriyama, Yoshinori; Sugiyama, Akifumi; Goossens, Alain; Moriyasu, Masataka; Yazaki, Kazufumi

    2014-01-01

    Alkaloids play a key role in higher plant defense against pathogens and herbivores. Following its biosynthesis in root tissues, nicotine, the major alkaloid of Nicotiana species, is translocated via xylem transport toward the accumulation sites, leaf vacuoles. Our transcriptome analysis of methyl jasmonate-treated tobacco BY-2 cells identified several multidrug and toxic compound extrusion (MATE) transporter genes. In this study, we characterized a MATE gene, Nicotiana tabacum jasmonate-inducible alkaloid transporter 2 (Nt-JAT2), which encodes a protein that has 32% amino acid identity with Nt-JAT1. Nt-JAT2 mRNA is expressed at a very low steady state level in whole plants, but is rapidly upregulated by methyl jasmonate treatment in a leaf-specific manner. To characterize the function of Nt-JAT2, yeast cells were used as the host organism in a cellular transport assay. Nt-JAT2 was localized at the plasma membrane in yeast cells. When incubated in nicotine-containing medium, the nicotine content in Nt-JAT2-expressing cells was significantly lower than in control yeast. Nt-JAT2-expressing cells also showed lower content of other alkaloids like anabasine and anatabine, but not of flavonoids, suggesting that Nt-JAT2 transports various alkaloids including nicotine. Fluorescence assays in BY-2 cells showed that Nt-JAT2-GFP was localized to the tonoplast. These findings indicate that Nt-JAT2 is involved in nicotine sequestration in leaf vacuoles following the translocation of nicotine from root tissues. PMID:25268729

  6. Evaluation of tobacco (Nicotiana tabacum L. cv. Petit Havana SR1) hairy roots for the production of geraniol, the first committed step in terpenoid indole alkaloid pathway.

    PubMed

    Ritala, Anneli; Dong, Lemeng; Imseng, Nicole; Seppänen-Laakso, Tuulikki; Vasilev, Nikolay; van der Krol, Sander; Rischer, Heiko; Maaheimo, Hannu; Virkki, Arho; Brändli, Johanna; Schillberg, Stefan; Eibl, Regine; Bouwmeester, Harro; Oksman-Caldentey, Kirsi-Marja

    2014-04-20

    The terpenoid indole alkaloids are one of the major classes of plant-derived natural products and are well known for their many applications in the pharmaceutical, fragrance and cosmetics industries. Hairy root cultures are useful for the production of plant secondary metabolites because of their genetic and biochemical stability and their rapid growth in hormone-free media. Tobacco (Nicotiana tabacum L. cv. Petit Havana SR1) hairy roots, which do not produce geraniol naturally, were engineered to express a plastid-targeted geraniol synthase gene originally isolated from Valeriana officinalis L. (VoGES). A SPME-GC-MS screening tool was developed for the rapid evaluation of production clones. The GC-MS analysis revealed that the free geraniol content in 20 hairy root clones expressing VoGES was an average of 13.7 μg/g dry weight (DW) and a maximum of 31.3 μg/g DW. More detailed metabolic analysis revealed that geraniol derivatives were present in six major glycoside forms, namely the hexose and/or pentose conjugates of geraniol and hydroxygeraniol, resulting in total geraniol levels of up to 204.3 μg/g DW following deglycosylation. A benchtop-scale process was developed in a 20-L wave-mixed bioreactor eventually yielding hundreds of grams of biomass and milligram quantities of geraniol per cultivation bag.

  7. Comparison of Thermobifida fusca Cellulases Expressed in Escherichia coli and Nicotiana tabacum Indicates Advantages of the Plant System for the Expression of Bacterial Cellulases.

    PubMed

    Klinger, Johannes; Fischer, Rainer; Commandeur, Ulrich

    2015-01-01

    The economic conversion of lignocellulosic biomass to biofuels requires in addition to pretreatment techniques access to large quantities of inexpensive cellulases to be competitive with established first generation processes. A solution to this problem could be achieved by plant based expression of these enzymes. We expressed the complete set of six cellulases and an additional β-glucosidase expressed from Thermobifida fusca in the bacterium Escherichia coli and in tobacco plants (Nicotiana tabacum). This was done to determine whether functional enzyme expression was feasible in these organisms. In extracts of recombinant E. coli cells, five of the proteins were detected by western blot analysis, but exocellulases E3 and E6 were undetectable. In the plant-based expression system we were able to detect all six cellulases but not the β-glucosidase even though activity was detectable. When E. coli was used as the expression system, endocellulase E2 was active, while endocellulases E1 and E5 showed only residual activity. The remaining cellulases appeared completely inactive against the model substrates azo-carboxymethyl-cellulose (Azo-CMC) and 4-methylumbelliferyl-cellobioside (4-MUC). Only the β-glucosidase showed high activity against 4-MUC. In contrast, all the plant-derived enzymes were active against the respective model substrates. Our data indicate that some enzymes of bacterial origin are more active and more efficiently expressed in plants than in a bacterial host.

  8. Effect of Potato Virus Y on the NADP-Malic Enzyme from Nicotiana tabacum L.: mRNA, Expressed Protein and Activity

    PubMed Central

    Doubnerová, Veronika; Müller, Karel; Čeřovská, Noemi; Synková, Helena; Spoustová, Petra; Ryšlavá, Helena

    2009-01-01

    The effect of biotic stress induced by viral infection (Potato virus Y, strain NTN and O) on NADP-malic enzyme (EC 1.1.1.40) in tobacco plants (Nicotiana tabacum L., cv. Petit Havana, SR1) was tested at the transcriptional, translational and activity level. The increase of enzyme activity in infected leaves was correlated with the increased amount of expressed protein and with mRNA of cytosolic NADP-ME isoform. Transcription of the chloroplastic enzyme was not influenced by viral infection. The increase of the enzyme activity was also detected in stems and roots of infected plants. The effect of viral infection induced by Potato virus Y, NTN strain, causing more severe symptoms, was compared with the effect induced by milder strain PVYO. The observed increase in NADP-malic enzyme activity in all parts of the studied plants was higher in the case of PVYNTN strain than in the case of strain PVYO. The relevance of NADP-malic enzyme in plants under stress conditions was discussed. PMID:20111689

  9. Tobacco plants transformed with the bean. alpha. ai gene express an inhibitor of insect. alpha. -amylase in their seeds. [Nicotiana tabacum; Tenebrio molitor

    SciTech Connect

    Altabella, T.; Chrispeels, M.J. )

    1990-06-01

    Bean (Phaseolus vulgaris L.) seeds contain a putative plant defense protein that inhibits insect and mammalian but not plant {alpha}-amylases. We recently presented strong circumstantial evidence that this {alpha}-amylase inhibitor ({alpha}Al) is encoded by an already-identified lectin gene whose product is referred to as lectin-like-protein (LLP). We have now made a chimeric gene consisting of the coding sequence of the lectin gene that encodes LLP and the 5{prime} and 3{prime} flanking sequences of the lectin gene that encodes phytohemagglutinin-L. When this chimeric gene was expressed in transgenic tobacco (Nicotiana tabacum), we observed in the seeds a series of polypeptides (M{sub r} 10,000-18,000) that cross-react with antibodies to the bean {alpha}-amylase inhibitor. Most of these polypeptides bind to a pig pancreas {alpha}-amylase affinity column. An extract of the seeds of the transformed tobacco plants inhibits pig pancreas {alpha}-amylase activity as well as the {alpha}-amylase present in the midgut of Tenebrio molitor. We suggest that introduction of this lectin gene (to be called {alpha}ai) into other leguminous plants may be a strategy to protect the seeds from the seed-eating larvae of Coleoptera.

  10. The Development of DNA Based Methods for the Reliable and Efficient Identification of Nicotiana tabacum in Tobacco and Its Derived Products

    PubMed Central

    Fan, Wei; Li, Rong; Li, Sifan; Ping, Wenli; Li, Shujun; Naumova, Alexandra; Peelen, Tamara; Yuan, Zheng; Zhang, Dabing

    2016-01-01

    Reliable methods are needed to detect the presence of tobacco components in tobacco products to effectively control smuggling and classify tariff and excise in tobacco industry to control illegal tobacco trade. In this study, two sensitive and specific DNA based methods, one quantitative real-time PCR (qPCR) assay and the other loop-mediated isothermal amplification (LAMP) assay, were developed for the reliable and efficient detection of the presence of tobacco (Nicotiana tabacum) in various tobacco samples and commodities. Both assays targeted the same sequence of the uridine 5′-monophosphate synthase (UMPS), and their specificities and sensitivities were determined with various plant materials. Both qPCR and LAMP methods were reliable and accurate in the rapid detection of tobacco components in various practical samples, including customs samples, reconstituted tobacco samples, and locally purchased cigarettes, showing high potential for their application in tobacco identification, particularly in the special cases where the morphology or chemical compositions of tobacco have been disrupted. Therefore, combining both methods would facilitate not only the detection of tobacco smuggling control, but also the detection of tariff classification and of excise. PMID:27635142

  11. Comparison of Thermobifida fusca Cellulases Expressed in Escherichia coli and Nicotiana tabacum Indicates Advantages of the Plant System for the Expression of Bacterial Cellulases

    PubMed Central

    Klinger, Johannes; Fischer, Rainer; Commandeur, Ulrich

    2015-01-01

    The economic conversion of lignocellulosic biomass to biofuels requires in addition to pretreatment techniques access to large quantities of inexpensive cellulases to be competitive with established first generation processes. A solution to this problem could be achieved by plant based expression of these enzymes. We expressed the complete set of six cellulases and an additional β-glucosidase expressed from Thermobifida fusca in the bacterium Escherichia coli and in tobacco plants (Nicotiana tabacum). This was done to determine whether functional enzyme expression was feasible in these organisms. In extracts of recombinant E. coli cells, five of the proteins were detected by western blot analysis, but exocellulases E3 and E6 were undetectable. In the plant-based expression system we were able to detect all six cellulases but not the β-glucosidase even though activity was detectable. When E. coli was used as the expression system, endocellulase E2 was active, while endocellulases E1 and E5 showed only residual activity. The remaining cellulases appeared completely inactive against the model substrates azo-carboxymethyl-cellulose (Azo-CMC) and 4-methylumbelliferyl-cellobioside (4-MUC). Only the β-glucosidase showed high activity against 4-MUC. In contrast, all the plant-derived enzymes were active against the respective model substrates. Our data indicate that some enzymes of bacterial origin are more active and more efficiently expressed in plants than in a bacterial host. PMID:26648951

  12. Distribution and change patterns of free IAA, ABP 1 and PM H⁺-ATPase during ovary and ovule development of Nicotiana tabacum L.

    PubMed

    Chen, Dan; Deng, Yingtian; Zhao, Jie

    2012-01-15

    Auxin plays key roles in flower induction, embryogenesis, seed formation and seedling development, but little is known about whether auxin regulates the development of ovaries and ovules before pollination. In the present report, we measured the content of free indole-3-acetic (IAA) in ovaries of Nicotiana tabacum L., and localized free IAA, auxin binding protein 1 (ABP1) and plasma membrane (PM) H⁺-ATPase in the ovaries and ovules. The level of free IAA in the developmental ovaries increased gradually from the stages of ovular primordium to the functional megaspore, but slightly decreased when the embryo sacs formed. Immunoenzyme labeling clearly showed that both IAA and ABP1 were distributed in the ovules, the edge of the placenta, vascular tissues and the ovary wall, while PM H⁺-ATPase was mainly localized in the ovules. By using immunogold labeling, the subcellular distributions of IAA, ABP1 and PM H⁺-ATPase in the ovules were also shown. The results suggest that IAA, ABP1 and PM H⁺-ATPase may play roles in the ovary and ovule initiation, formation and differentiation.

  13. Exclusion of a Proton ATPase from the Apical Membrane Is Associated with Cell Polarity and Tip Growth in Nicotiana tabacum Pollen Tubes[W

    PubMed Central

    Certal, Ana C.; Almeida, Ricardo B.; Carvalho, Lara M.; Wong, Eric; Moreno, Nuno; Michard, Erwan; Carneiro, Jorge; Rodriguéz-Léon, Joaquín; Wu, Hen-Ming; Cheung, Alice Y.; Feijó, José A.

    2008-01-01

    Polarized growth in pollen tubes results from exocytosis at the tip and is associated with conspicuous polarization of Ca2+, H+, K+, and Cl− -fluxes. Here, we show that cell polarity in Nicotiana tabacum pollen is associated with the exclusion of a novel pollen-specific H+-ATPase, Nt AHA, from the growing apex. Nt AHA colocalizes with extracellular H+ effluxes, which revert to influxes where Nt AHA is absent. Fluorescence recovery after photobleaching analysis showed that Nt AHA moves toward the apex of growing pollen tubes, suggesting that the major mechanism of insertion is not through apical exocytosis. Nt AHA mRNA is also excluded from the tip, suggesting a mechanism of polarization acting at the level of translation. Localized applications of the cation ionophore gramicidin A had no effect where Nt AHA was present but acidified the cytosol and induced reorientation of the pollen tube where Nt AHA was absent. Transgenic pollen overexpressing Nt AHA-GFP developed abnormal callose plugs accompanied by abnormal H+ flux profiles. Furthermore, there is no net flux of H+ in defined patches of membrane where callose plugs are to be formed. Taken together, our results suggest that proton dynamics may underlie basic mechanisms of polarity and spatial regulation in growing pollen tubes. PMID:18364468

  14. Difference of physiological characters in dark green islands and yellow leaf tissue of Cucumber mosaic virus (CMV)-infected Nicotiana tabacum leaves.

    PubMed

    Shang, Jing; Xi, De-Hui; Yuan, Shu; Xu, Fei; Xu, Mo-Yun; Qi, Hai-Long; Wang, Shao-Dong; Huang, Qing-Rong; Wen, Lin; Lin, Hong-Hui

    2010-01-01

    Dark green islands (DGIs) are a common symptom of plants systemically infected with the mosaic virus. DGIs are clusters of green leaf cells that are free of virus but surrounded by yellow leaf tissue that is full of virus particles. In Cucumber mosaic virus (CMV)-infected Nicotiana tabacum leaves, the respiration and photosynthesis capabilities of DGIs and yellow leaf tissues were measured. The results showed that the cyanide-resistant respiration was enhanced in yellow leaf tissue and the photosynthesis was declined, while in DGIs they were less affected. The activities of the oxygen-scavenging enzymes catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) in infected leaves were significantly higher than those in the healthy leaves, and the enzyme activities in DGIs were always lower than in the yellow leaf tissues. Reactive oxygen species (ROS) staining showed that the hydrogen peroxide content in yellow leaf tissues was apparently higher than that in DGIs, while the superoxide content was on the contrary. Formation of DGIs may be a strategy of the host plants resistance to the CMV infection.

  15. iTRAQ-based quantitative proteomic analysis reveals proteomic changes in leaves of cultivated tobacco (Nicotiana tabacum) in response to drought stress.

    PubMed

    Xie, He; Yang, Da-Hai; Yao, Heng; Bai, Ge; Zhang, Yi-Han; Xiao, Bing-Guang

    2016-01-15

    Drought is one of the most severe forms of abiotic stresses that threaten the survival of plants, including crops. In turn, plants dramatically change their physiology to increase drought tolerance, including reconfiguration of proteomes. Here, we studied drought-induced proteomic changes in leaves of cultivated tobacco (Nicotiana tabacum), a solanaceous plant, using the isobaric tags for relative and absolute quantitation (iTRAQ)-based protein labeling technology. Of identified 5570 proteins totally, drought treatment increased and decreased abundance of 260 and 206 proteins, respectively, compared with control condition. Most of these differentially regulated proteins are involved in photosynthesis, metabolism, and stress and defense. Although abscisic acid (ABA) levels greatly increased in drought-treated tobacco leaves, abundance of detected ABA biosynthetic enzymes showed no obvious changes. In contrast, heat shock proteins (HSPs), thioredoxins, ascorbate-, glutathione-, and hydrogen peroxide (H2O2)-related proteins were up- or down-regulated in drought-treated tobacco leaves, suggesting that chaperones and redox signaling are important for tobacco tolerance to drought, and it is likely that redox-induced posttranslational modifications play an important role in modulating protein activity. This study not only provides a comprehensive dataset on overall protein changes in drought-treated tobacco leaves, but also shed light on the mechanism by which solanaceous plants adapt to drought stress.

  16. Salinity-induced accumulation of endogenous H2S and NO is associated with modulation of the antioxidant and redox defense systems in Nicotiana tabacum L. cv. Havana.

    PubMed

    da Silva, Cristiane Jovelina; Batista Fontes, Elizabeth Pacheco; Modolo, Luzia Valentina

    2017-03-01

    Salinity is one of the abiotic factors that most affect crop growth and production. This study focused on the effect of high salinity on the endogenous levels of the signaling molecules hydrogen sulfite (H2S) and nitric oxide (NO) in Nicotiana tabacum leaves and the extent of these for the biochemically-driven plant tolerance to such abiotic stress. The NaCl treatment for 10days led to an expressive augment of H2S and NO levels. This increase was correlated with the raise of l-Cys and l-Arg and the induction of l-cysteine desulfhydrase, cyanoalanine synthase, cysteine synthase, nitrate reductase and arginase, enzymes known to be involved in the biosynthesis of H2S or NO. The enzymatic antioxidant system (superoxide dismutase and catalase activity) was boosted and the non-enzymatic antioxidant glutathione was intensively oxidized in leaves upon stress allowing plants to cope with oxidative stress. Lower stomatal conductance was observed in stressed plants in comparison with control ones. Moreover, the high activity of antioxidant enzymes and high rate of glutathione oxidation following salt stress were considerably decreased upon NO or H2S scavenging. Thus, increment in NO and H2S levels and their interplay, along with metabolic and physiological changes, contributed to tobacco survival to extreme salinity conditions.

  17. Nicotiana tabacum EIL2 directly regulates expression of at least one tobacco gene induced by sulphur starvation.

    PubMed

    Wawrzyńska, Anna; Lewandowska, Małgorzata; Sirko, Agnieszka

    2010-03-01

    Sulphur deficiency severely affects plant growth and their agricultural productivity leading to diverse changes in development and metabolisms. Molecular mechanisms regulating gene expression under low sulphur conditions remain largely unknown. AtSLIM1, a member of the EIN3-like (EIL) family was reported to be a central transcriptional regulator of the plant sulphur response, however, no direct interaction of this protein with any sulphur-responsive promoters was demonstrated. The focus of this study was on the analysis of a promoter region of UP9C, a tobacco gene strongly induced by sulphur limitation. Cloning and subsequent examination of this promoter resulted in the identification of a 20-nt sequence (UPE-box), also present in the promoters of several Arabidopsis genes, including three out of four homologues of UP9C. The UPE-box, consisting of two parallel tebs sequences (TEIL binding site), proved to be necessary to bind the transcription factors belonging to the EIL family and of a 5-nt conserved sequence at the 3'-end. The yeast one-hybrid analysis resulted in the identification of one transcription factor (NtEIL2) capable of binding to the UPE-box. The interactions of NtEIL2, and its homologue from Arabidopsis, AtSLIM1, with DNA were affected by mutations within the UPE-box. Transient expression assays in Nicotiana benthamiana have further shown that both factors, NtEIL2 and AtSLIM1, activate the UP9C promoter. Interestingly, activation by NtEIL2, but not by AtSLIM1, was dependent on the sulphur-deficiency of the plants.

  18. Ectopic expression of class 1 KNOX genes induce adventitious shoot regeneration and alter growth and development of tobacco (Nicotiana tabacum L) and European plum (Prunus domestica L).

    PubMed

    Srinivasan, C; Liu, Zongrang; Scorza, Ralph

    2011-04-01

    Transgenic plants of tobacco (Nicotiana tabacum L) and European plum (Prunus domestica L) were produced by transforming with the apple class 1 KNOX genes (MdKN1 and MdKN2) or corn KNOX1 gene. Transgenic tobacco plants were regenerated in vitro from transformed leaf discs cultured in a medium lacking cytokinin. Ectopic expression of KNOX genes retarded shoot growth by suppressing elongation of internodes in transgenic tobacco plants. Expression of each of the three KNOX1 genes induced malformation and extensive lobbing in tobacco leaves. In situ regeneration of adventitious shoots was observed from leaves and roots of transgenic tobacco plants expressing each of the three KNOX genes. In vitro culture of leaf explants and internode sections excised from in vitro grown MdKN1 expressing tobacco shoots regenerated adventitious shoots on MS (Murashige and Skoog 1962) basal medium in the absence of exogenous cytokinin. Transgenic plum plants that expressed the MdKN2 or corn KNOX1 gene grew normally but MdKN1 caused a significant reduction in plant height, leaf shape and size and produced malformed curly leaves. A high frequency of adventitious shoot regeneration (96%) was observed in cultures of leaf explants excised from corn KNOX1-expressing transgenic plum shoots. In contrast to KNOX1-expressing tobacco, leaf and internode explants of corn KNOX1-expressing plum required synthetic cytokinin (thidiazuron) in the culture medium to induce adventitious shoot regeneration. The induction of high-frequency regeneration of adventitious shoots in vitro from leaves and stem internodal sections of plum through the ectopic expression of a KNOX1 gene is the first such report for a woody perennial fruit trees.

  19. Tolerance to clomazone herbicide is linked to the state of LHC, PQ-pool and ROS detoxification in tobacco (Nicotiana tabacum L.).

    PubMed

    Darwish, Majd; Vidal, Véronique; Lopez-Lauri, Félicie; Alnaser, Osama; Junglee, Sanders; El Maataoui, Mohamed; Sallanon, Huguette

    2015-03-01

    In this study, plantlets of two tobacco (Nicotiana tabacum L.) varieties that are clomazone-tolerant (cv. Xanthi) and clomazone-sensitive (cv. Virginie vk51) were subjected to low concentration of clomazone herbicide. The oxygen-evolving rate of isolated chloroplasts, chlorophyll a fluorescence transients, JIP-test responses, hydrogen peroxide contents, antioxidant enzyme activities, cytohistological results and photosynthetic pigment contents were recorded. The results indicated that the carotenoid content was 2-fold higher in Virginie, which had greater clomazone sensitivity than Xanthi. Virginie exhibited noticeable decreases in the LHC content (Chl a/b ratio), the maximum photochemical quantum efficiency of PSII (Fv/Fm), the performance index on the absorption basis (PIabs), and the electron flux beyond the first PSII QA evaluated as (1-VJ) with VJ=(FJ-F0)/(Fm-F0) as well as increases in the rate of photon absorption (ABS/RC) and the energy dissipation as heat (DI0/RC). These results suggest that PSII photoinhibition occurred as a consequence of more reduced PQ-pool and accumulated QA(-). The oxygen evolution measurements indicate that PSI electron transport activity was not affected by clomazone. The more significant accumulation of H2O2 in Virginie compared to Xanthi was due to the absence of ROS-scavenging enzymes, and presumably induced programmed cell death (PCD). The symptoms of PCD were observed by cytohistological analysis, which also indicated that the leaf tissues of clomazone-treated Virginie exhibited significant starch accumulation compared to Xanthi. Taken together, these results indicate that the variable tolerance to clomazone observed between Virginie and Xanthi is independent of the carotenoid content and could be related to the state of the LHC, the redox state of the PQ-pool, and the activity of detoxification enzymes.

  20. RNAi based simultaneous silencing of all forms of light-dependent NADPH:protochlorophyllide oxidoreductase genes result in the accumulation of protochlorophyllide in tobacco (Nicotiana tabacum).

    PubMed

    Talaat, Neveen B

    2013-10-01

    Conversion of protochlorophyllide (Pchlide) into chlorophyllide (Chlide), a key step in chlorophyll biosynthesis, is mediated by a light-dependent NADPH:protochlorophyllide oxidoreductase (POR). POR exists in multiple isoforms that share high degree of homology. RNAi-mediated gene silencing approach was used to suppress the expression of POR genes in order to study its role in the Chls biosynthesis in tobacco (Nicotiana tabacum L.). The transgenic plants were devoid of chlorophyll pigments and resembled albino plants. Northern blot analysis confirmed the degradation of POR transcripts into 21-23 bp fragments. Pigment analysis showed the accumulation of various intermediate compounds of Chl biosynthesis pathway including Pchlide. However, no trace of chlorophyll was observed. As compared to wild type, POR-silenced plants accumulated larger (60%) amounts of Pchlide from its endogenous substrate. When leaf discs of WT and POR-silenced plants were treated with exogenous ALA both WT and POR-silenced plants accumulated large amounts of tetrapyrrolic intermediates demonstrating that Pchlide biosynthesis potential was not suppressed in POR-silenced plants. Upon illumination, WT plants photo-transformed large amounts of Pchlide to Chlide. However, POR-silenced plants almost completely failed to do so. Results demonstrate that the antisense approaches to drop expression of individual POR isoforms have provided valuable insights into the role of distinct PORs during greening. Moreover, data illustrate that the POR is the only enzyme that can convert the Pchlide to Chlide and there is no alternate enzyme that can substitute the POR in higher plants. Thus, this investigation describes ideal mechanism for the silencing of POR isozymes in tobacco.

  1. Pneumatic hydrodynamics influence transplastomic protein yields and biological responses during in vitro shoot regeneration of Nicotiana tabacum callus: Implications for bioprocess routes to plant-made biopharmaceuticals.

    PubMed

    Barretto, Sherwin S; Michoux, Franck; Hellgardt, Klaus; Nixon, Peter J

    2017-01-15

    Transplastomic plants are capable of high-yield production of recombinant biopharmaceutical proteins. Plant tissue culture combines advantages of agricultural cultivation with the bioprocess consistency associated with suspension culture. Overexpression of recombinant proteins through regeneration of transplastomic Nicotiana tabacum shoots from callus tissue in RITA(®) temporary immersion bioreactors has been previously demonstrated. In this study we investigated the hydrodynamics of periodic pneumatic suspension of liquid medium during temporary immersion culture (4 min aeration every 8 h), and the impact on biological responses and transplastomic expression of fragment C of tetanus toxin (TetC). Biomass was grown under a range of aeration rates for 3, 20 and 40-day durations. Growth, mitochondrial activity (a viability indicator) and TetC protein yields were correlated against the hydrodynamic parameters, shear rate and energy dissipation rate (per kg of medium). A critical aeration rate of 440 ml min(-1) was identified, corresponding to a shear rate of 96.7 s(-1), pneumatic power input of 8.8 mW kg(-1) and initial 20-day pneumatic energy dissipation of 127 J kg(-1), at which significant reductions in biomass accumulation and mitochondrial activity were observed. There was an exponential decline in TetC yields with increasing aeration rates at 40 days, across the entire range of conditions tested. These observations have important implications for the optimisation and scale-up of transplastomic plant tissue culture bioprocesses for biopharmaceutical production.

  2. Different blue-light requirement for the accumulation of transcripts from nuclear genes for thylakoid proteins in Nicotiana tabacum and Lycopersicon esculentum.

    PubMed

    Palomares, R; Herrmann, R G; Oelmüller, R

    1991-11-01

    We have isolated recombinant lambda gt11 phages which carry cDNA clones for the major light-harvesting chlorophyll a/b-binding proteins of photosystem I (LHCPI) and II (LHCPII), subunit II of photosystem I, a chlorophyll a/b-binding protein of photosystem II (CP24), the Rieske iron-sulphur protein of the cytochrome b6/f complex, and the 33, 23 and 16 kDa proteins of the water-oxidizing complex of photosystem II from Nicotiana tabacum. The nucleotide sequences of cDNA clones encoding the precursors for LHCPI and the FeS protein are presented. If tobacco or tomato seedlings, or seedlings of a phytochrome-deficient aurea mutant of tomato which lacks more than 95% of the phytochrome of the isogenic wild type, are kept in blue light, the transcript level of each of these genes is higher than in seedlings grown in red light suggesting the involvement of a blue-UVA-light photoreceptor. In the case of LHCPI, a 1 min blue-light pulse applied to red-light-grown seedlings is sufficient to increase the transcript levels to those present in blue-light-grown seedlings, whereas almost no increase is observed for transcripts encoding the FeS and 33 kDa proteins. If dark-grown tomato seedlings receive a single far-red-light pulse, significant stimulation is detected for LHCPI transcripts, whereas transcripts encoding the FeS and 33 kDa proteins are not stimulated. It is concluded that the lower light requirement for the increase in the LHCPI transcript level is not specific for one of the light-dependent signal transduction chains.

  3. Herbivory: Caterpillar saliva beats plant defences

    NASA Astrophysics Data System (ADS)

    Musser, Richard O.; Hum-Musser, Sue M.; Eichenseer, Herb; Peiffer, Michelle; Ervin, Gary; Murphy, J. Brad; Felton, Gary W.

    2002-04-01

    Blood-feeding arthropods secrete special salivary proteins that suppress the defensive reaction they induce in their hosts. This is in contrast to herbivores, which are thought to be helpless victims of plant defences elicited by their oral secretions. On the basis of the finding that caterpillar regurgitant can reduce the amount of toxic nicotine released by the tobacco plant Nicotiana tabacum, we investigate here whether specific salivary components from the caterpillar Helicoverpa zea might be responsible for this suppression. We find that the enzyme glucose oxidase counteracts the production of nicotine induced by the caterpillar feeding on the plant.

  4. Inactivation of the β(1,2)-xylosyltransferase and the α(1,3)-fucosyltransferase genes in Nicotiana tabacum BY-2 Cells by a Multiplex CRISPR/Cas9 Strategy Results in Glycoproteins without Plant-Specific Glycans

    PubMed Central

    Mercx, Sébastien; Smargiasso, Nicolas; Chaumont, François; De Pauw, Edwin; Boutry, Marc; Navarre, Catherine

    2017-01-01

    Plants or plant cells can be used to produce pharmacological glycoproteins such as antibodies or vaccines. However these proteins carry N-glycans with plant-typical residues [β(1,2)-xylose and core α(1,3)-fucose], which can greatly impact the immunogenicity, allergenicity, or activity of the protein. Two enzymes are responsible for the addition of plant-specific glycans: β(1,2)-xylosyltransferase (XylT) and α(1,3)-fucosyltransferase (FucT). Our aim consisted of knocking-out two XylT genes and four FucT genes (12 alleles altogether) in Nicotiana tabacum BY-2 suspension cells using CRISPR/Cas9. Three XylT and six FucT sgRNAs were designed to target conserved regions. After transformation of N. tabacum BY-2 cells with genes coding for sgRNAs, Cas9, and a selectable marker (bar), transgenic lines were obtained and their extracellular as well as intracellular protein complements were analyzed by Western blotting using antibodies recognizing β(1,2)-xylose and α(1,3)-fucose. Three lines showed a strong reduction of β(1,2)-xylose and α(1,3)-fucose, while two lines were completely devoid of them, indicating complete gene inactivation. The absence of these carbohydrates was confirmed by mass spectrometry analysis of the extracellular proteins. PCR amplification and sequencing of the targeted region indicated small INDEL and/or deletions between the target sites. The KO lines did not show any particular morphology and grew as the wild-type. One KO line was transformed with genes encoding a human IgG2 antibody. The IgG2 expression level was as high as in a control transformant which had not been glycoengineered. The IgG glycosylation profile determined by mass spectrometry confirmed that no β(1,2)-xylose or α(1,3)-fucose were present on the glycosylation moiety and that the dominant glycoform was the GnGn structure. These data represent an important step toward humanizing the glycosylation of pharmacological proteins expressed in N. tabacum BY-2 cells.

  5. Na⁺/H⁺ exchanger 1 participates in tobacco disease defence against Phytophthora parasitica var. nicotianae by affecting vacuolar pH and priming the antioxidative system.

    PubMed

    Chen, Xianyang; Bao, Hexigeduleng; Guo, Jie; Jia, Weitao; Tai, Fang; Nie, Lingling; Jiang, Ping; Feng, Juanjuan; Lv, Sulian; Li, Yinxin

    2014-11-01

    Despite the importance of NHX1 (Na(+)/H(+) exchanger 1) in plant salt tolerance, little is known about its other functions. In this study, intriguingly, it was found that NHX1 participated in plant disease defence against Phytophthora parasitica var. nicotianae (Ppn) in Nicotiana benthamiana. NbNHX1 was originally isolated from N. benthamiana, and characterized. The subcellular localization of NbNHX1 with its C-terminus fused with green fluorescent protein indicated that NbNHX1 localized primarily to the tonoplast. Tobacco rattle virus-induced NbNHX1 silencing led to reduced H(+) efflux from the vacuole to cytoplasts, and decreased Ppn resistance in N. benthamiana. After attack by Ppn, NbNHX1-silenced plants exhibited impaired ability to scavenge reactive oxidative species (ROS) induced by the pathogen. Pea early browning virus-mediated ectopic expression of SeNHX1 (from Salicornia europaea) or AtNHX1 (from Arabidopsis thaliana) both conferred enhanced Ppn resistance to N. benthamiana, with a lower H2O2 concentration after Ppn inoculation. Further investigation of the role of NHX1 demonstrated that transient overexpression of NbNHX1 improved the vacuolar pH and cellular ROS level in N. benthamiana, which was coupled with an enlarged NAD(P) (H) pool and higher expression of ROS-responsive genes. In contrast, NbNHX1 silencing led to a lower pH in the vacuole and a lower cellular ROS level in N. benthamiana, which was coupled with a decreased NAD(P) (H) pool and decreased expression of ROS-responsive genes. These results suggest that NHX1 is involved in plant disease defence; and regulation of vacuolar pH by NHX1, affecting the cellular oxidation state, primes the antioxidative system which is associated with Ppn resistance in tobacco.

  6. Activity of the AtMRP3 promoter in transgenic Arabidopsis thaliana and Nicotiana tabacum plants is increased by cadmium, nickel, arsenic, cobalt and lead but not by zinc and iron.

    PubMed

    Zientara, Katarzyna; Wawrzyńska, Anna; Lukomska, Jolanta; López-Moya, José Rafael; Liszewska, Frantz; Assunção, Ana G L; Aarts, Mark G M; Sirko, Agnieszka

    2009-02-05

    Characterization of the function, regulation and metal-specificity of metal transporters is one of the basic steps needed for the understanding of transport and accumulation of toxic metals and metalloids by plants. In this work GUS was used as a reporter for monitoring the activity of the promoter of the AtMRP3 gene from Arabidopsis thaliana, a gene encoding an ABC-transporter, expression of which is induced by heavy metals. The AtMRP3 promoter-GUS fusion expression cassette was introduced into the genome of two model plants, A. thaliana and Nicotiana tabacum. The promoter induces GUS activity in the roots as well as in the shoots upon metal exposure. Similar responses of the AtMRP3 promoter to the presence of the selected metals was observed in both plant species. Cadmium, nickel, arsenic, cobalt and lead strongly activated the transcription of the reporter gene, while zinc and iron had no impact. The AtMRP3 promoter thus seems to be a useful new tool in designing plants that can be used for biomonitoring of environmental contaminations.

  7. Nuclear-encoded chloroplast ribosomal protein L12 of Nicotiana tabacum: characterization of mature protein and isolation and sequence analysis of cDNA clones encoding its cytoplasmic precursor.

    PubMed Central

    Elhag, G A; Thomas, F J; McCreery, T P; Bourque, D P

    1992-01-01

    Poly(A)+ mRNA isolated from Nicotiana tabacum (cv. Petite Havana) leaves was used to prepare a cDNA library in the expression vector lambda gt11. Recombinant phage containing cDNAs coding for chloroplast ribosomal protein L12 were identified and sequenced. Mature tobacco L12 protein has 44% amino acid identity with ribosomal protein L7/L12 of Escherichia coli. The longest L12 cDNA (733 nucleotides) codes for a 13,823 molecular weight polypeptide with a transit peptide of 53 amino acids and a mature protein of 133 amino acids. The transit peptide and mature protein share 43% and 79% amino acid identity, respectively, with corresponding regions of spinach chloroplast ribosomal protein L12. The predicted amino terminus of the mature protein was confirmed by partial sequence analysis of HPLC-purified tobacco chloroplast ribosomal protein L12. A single L12 mRNA of about 0.8 kb was detected by hybridization of L12 cDNA to poly(A)+ and total leaf RNA. Hybridization patterns of restriction fragments of tobacco genomic DNA probed with the L12 cDNA suggested the existence of more than one gene for ribosomal protein L12. Characterization of a second cDNA with an identical L12 coding sequence but a different 3'-noncoding sequence provided evidence that at least two L12 genes are expressed in tobacco. Images PMID:1542565

  8. Involvement of phospholipases C and D in the defence responses of riboflavin-treated tobacco cells.

    PubMed

    Wang, Lianlian; Zhu, Xiaoping; Liu, Jinwei; Chu, Xiaojing; Jiao, Jiao; Liang, Yuancun

    2013-04-01

    Riboflavin is an activator of defence responses in plants that increases resistance against diseases caused by fungal, oomycete, bacterial and viral pathogens. However, the mechanisms driving defence activation by riboflavin are poorly understood. We investigated the signal transduction pathways of phospholipase C (PLC) and phospholipase D (PLD) in tobacco (Nicotiana tabacum) suspension cells using a pharmacological approach to confirm whether riboflavin-mediated activation of the defence response is dependent on both PLC and PLD. The expression patterns analysed by quantitative reverse transcription-polymerase chain reaction demonstrated that the tobacco PLC and PLD gene families were differentially expressed in riboflavin-treated tobacco cells. PLC and PLD expression accompanied defence responses including the expression of defence response genes (PAL, PR-1a and PR-1b), the production of hydrogen peroxide and the accumulation of the phytoalexin scopoletin in tobacco cells treated with riboflavin. These defence responses were significantly inhibited in the presence of the PLC inhibitor U73122 and the PLD inhibitor 1-butanol; however, inhibitor analogues had no effect. Moreover, treating tobacco cells with phosphatidic acid, a signalling molecule produced by phospholipase catalysis, induced the accumulation of the phytoalexin scopoletin and compensated for the suppressive effects of U73122 and 1-butanol on riboflavin-induced accumulation of the phytoalexin. These results offer pharmacological evidence that PLC and PLD play a role in riboflavin-induced defences of tobacco.

  9. Involvement of the putative Ca²⁺-permeable mechanosensitive channels, NtMCA1 and NtMCA2, in Ca²⁺ uptake, Ca²⁺-dependent cell proliferation and mechanical stress-induced gene expression in tobacco (Nicotiana tabacum) BY-2 cells.

    PubMed

    Kurusu, Takamitsu; Yamanaka, Takuya; Nakano, Masataka; Takiguchi, Akiko; Ogasawara, Yoko; Hayashi, Teruyuki; Iida, Kazuko; Hanamata, Shigeru; Shinozaki, Kazuo; Iida, Hidetoshi; Kuchitsu, Kazuyuki

    2012-07-01

    To gain insight into the cellular functions of the mid1-complementing activity (MCA) family proteins, encoding putative Ca²⁺-permeable mechanosensitive channels, we isolated two MCA homologs of tobacco (Nicotiana tabacum) BY-2 cells, named NtMCA1 and NtMCA2. NtMCA1 and NtMCA2 partially complemented the lethality and Ca²⁺ uptake defects of yeast mutants lacking mechanosensitive Ca²⁺ channel components. Furthermore, in yeast cells overexpressing NtMCA1 and NtMCA2, the hypo-osmotic shock-induced Ca²⁺ influx was enhanced. Overexpression of NtMCA1 or NtMCA2 in BY-2 cells enhanced Ca²⁺ uptake, and significantly alleviated growth inhibition under Ca²⁺ limitation. NtMCA1-overexpressing BY-2 cells showed higher sensitivity to hypo-osmotic shock than control cells, and induced the expression of the touch-inducible gene, NtERF4. We found that both NtMCA1-GFP and NtMCA2-GFP were localized at the plasma membrane and its interface with the cell wall, Hechtian strands, and at the cell plate and perinuclear vesicles of dividing cells. NtMCA2 transcript levels fluctuated during the cell cycle and were highest at the G1 phase. These results suggest that NtMCA1 and NtMCA2 play roles in Ca²⁺-dependent cell proliferation and mechanical stress-induced gene expression in BY-2 cells, by regulating the Ca²⁺ influx through the plasma membrane.

  10. Deep sequencing of the ancestral tobacco species Nicotiana tomentosiformis reveals multiple T-DNA inserts and a complex evolutionary history of natural transformation in the genus Nicotiana.

    PubMed

    Chen, Ke; Dorlhac de Borne, François; Szegedi, Ernö; Otten, Léon

    2014-11-01

    Nicotiana species carry cellular T-DNA sequences (cT-DNAs), acquired by Agrobacterium-mediated transformation. We characterized the cT-DNA sequences of the ancestral Nicotiana tabacum species Nicotiana tomentosiformis by deep sequencing. N. tomentosiformis contains four cT-DNA inserts derived from different Agrobacterium strains. Each has an incomplete inverted-repeat structure. TA is similar to part of the Agrobacterium rhizogenes 1724 mikimopine-type T-DNA, but has unusual orf14 and mis genes. TB carries a 1724 mikimopine-type orf14-mis fragment and a mannopine-agropine synthesis region (mas2-mas1-ags). The mas2' gene codes for an active enzyme. TC is similar to the left part of the A. rhizogenes A4 T-DNA, but also carries octopine synthase-like (ocl) and c-like genes normally found in A. tumefaciens. TD shows a complex rearrangement of T-DNA fragments similar to the right end of the A4 TL-DNA, and including an orf14-like gene and a gene with unknown function, orf511. The TA, TB, TC and TD insertion sites were identified by alignment with N. tabacum and Nicotiana sylvestris sequences. The divergence values for the TA, TB, TC and TD repeats provide an estimate for their relative introduction times. A large deletion has occurred in the central part of the N. tabacum cv. Basma/Xanthi TA region, and another deletion removed the complete TC region in N. tabacum. Nicotiana otophora lacks TA, TB and TD, but contains TC and another cT-DNA, TE. This analysis, together with that of Nicotiana glauca and other Nicotiana species, indicates multiple sequential insertions of cT-DNAs during the evolution of the genus Nicotiana.

  11. Genetic variation in alkaloid accumulation in leaves of Nicotiana.

    PubMed

    Sun, Bo; Zhang, Fen; Zhou, Guo-jun; Chu, Guo-hai; Huang, Fang-fang; Wang, Qiao-mei; Jin, Li-feng; Lin, Fu-cheng; Yang, Jun

    2013-12-01

    Alkaloids are plant secondary metabolites that are widely distributed in Nicotiana species and contribute greatly to the quality of tobacco leaves. Some alkaloids, such as nornicotine and myosmine, have adverse effects on human health. To reduce the content of harmful alkaloids in tobacco leaves through conventional breeding, a genetic study of the alkaloid variation among different genotypes is required. In this study, alkaloid profiles in leaves of five Nicotiana tabacum cultivars and Nicotiana tomentosiformis were investigated. Six alkaloids were identified from all six genotypes via gas chromatograph-mass spectrometry (GC-MS). Significant differences in alkaloid content were observed both among different leaf positions and among cultivars. The contents of nornicotine and myosmine were positively and significantly correlated (R(2)=0.881), and were also separated from those of other alkaloids by clustering. Thus, the genotype plays a major role in alkaloid accumulation, indicating a high potential for manipulation of alkaloid content through traditional breeding.

  12. Current status and prospects for the study of Nicotiana genomics, genetics, and nicotine biosynthesis genes.

    PubMed

    Wang, Xuewen; Bennetzen, Jeffrey L

    2015-02-01

    Nicotiana, a member of the Solanaceae family, is one of the most important research model plants, and of high agricultural and economic value worldwide. To better understand the substantial and rapid research progress with Nicotiana in recent years, its genomics, genetics, and nicotine gene studies are summarized, with useful web links. Several important genetic maps, including a high-density map of N. tabacum consisting of ~2,000 markers published in 2012, provide tools for genetics research. Four whole genome sequences are from allotetraploid species, including N. benthamiana in 2012, and three N. tabacum cultivars (TN90, K326, and BX) in 2014. Three whole genome sequences are from diploids, including progenitors N. sylvestris and N. tomentosiformis in 2013 and N. otophora in 2014. These and additional studies provide numerous insights into genome evolution after polyploidization, including changes in gene composition and transcriptome expression in N. tabacum. The major genes involved in the nicotine biosynthetic pathway have been identified and the genetic basis of the differences in nicotine levels among Nicotiana species has been revealed. In addition, other progress on chloroplast, mitochondrial, and NCBI-registered projects on Nicotiana are discussed. The challenges and prospects for genomic, genetic and application research are addressed. Hence, this review provides important resources and guidance for current and future research and application in Nicotiana.

  13. Imposed glutathione-mediated redox switch modulates the tobacco wound-induced protein kinase and salicylic acid-induced protein kinase activation state and impacts on defence against Pseudomonas syringae.

    PubMed

    Matern, Sanja; Peskan-Berghoefer, Tatjana; Gromes, Roland; Kiesel, Rebecca Vazquez; Rausch, Thomas

    2015-04-01

    The role of the redox-active tripeptide glutathione in plant defence against pathogens has been studied extensively; however, the impact of changes in cellular glutathione redox potential on signalling processes during defence reactions has remained elusive. This study explored the impact of elevated glutathione content on the cytosolic redox potential and on early defence signalling at the level of mitogen-activated protein kinases (MAPKs), as well as on subsequent defence reactions, including changes in salicylic acid (SA) content, pathogenesis-related gene expression, callose depositions, and the hypersensitive response. Wild-type (WT) Nicotiana tabacum L. and transgenic high-glutathione lines (HGL) were transformed with the cytosol-targeted sensor GRX1-roGFP2 to monitor the cytosolic redox state. Surprisingly, HGLs displayed an oxidative shift in their cytosolic redox potential and an activation of the tobacco MAPKs wound-induced protein kinase (WIPK) and SA-induced protein kinase (SIPK). This activation occurred in the absence of any change in free SA content, but was accompanied by constitutively increased expression of several defence genes. Similarly, rapid activation of MAPKs could be induced in WT tobacco by exposure to either reduced or oxidized glutathione. When HGL plants were challenged with adapted or non-adapted Pseudomonas syringae pathovars, the cytosolic redox shift was further amplified and the defence response was markedly increased, showing a priming effect for SA and callose; however, the initial and transient hyperactivation of MAPK signalling was attenuated in HGLs. The results suggest that, in tobacco, MAPK and SA signalling may operate independently, both possibly being modulated by the glutathione redox potential. Possible mechanisms for redox-mediated MAPK activation are discussed.

  14. Relationship between Active Oxygen Species, Lipid Peroxidation, Necrosis, and Phytoalexin Production Induced by Elicitins in Nicotiana.

    PubMed Central

    Rusterucci, C.; Stallaert, V.; Milat, M. L.; Pugin, A.; Ricci, P.; Blein, J. P.

    1996-01-01

    Excised leaves of Nicotiana tabacum var Xanthi and Nicotiana rustica were treated with cryptogein and capsicein, basic and acidic elicitins, respectively. Both compounds induced leaf necrosis, the intensity of which depended on concentration and duration of treatment. N. tabacum var Xanthi was the most sensitive species and cryptogein was the most active elicitin. Lipid peroxidation in elicitin-treated Nicotiana leaves was closely correlated with the appearance of necrosis. Elicitin treatments induced a rapid and transient burst of active oxygen species (AOS) in cell cultures of both Nicotiana species, with the production by Xanthi cells being 6-fold greater than that by N. rustica. Similar maximum AOS production levels were observed with both elicitins, but capsicein required 10-fold higher concentrations than those of cryptogein. Phytoalexin production was lower in response to both elicitins in N. tabacum var Xanthi cells than in N. rustica cells, and capsicein was the most efficient elicitor of this response. In cryptogein-treated cell suspensions, phytoalexin synthesis was unaffected by diphenyleneiodonium, which inhibited AOS generation, nor was it affected by tiron or catalase, which suppressed AOS accumulation in the extracellular medium. These results suggest that AOS production, lipid peroxidation, and necrosis are directly related, whereas phytoalexin production depends on neither the presence nor the intensity of these responses. PMID:12226334

  15. Complete Chloroplast Genome of Nicotiana otophora and its Comparison with Related Species

    PubMed Central

    Asaf, Sajjad; Khan, Abdul L.; Khan, Abdur R.; Waqas, Muhammad; Kang, Sang-Mo; Khan, Muhammad A.; Lee, Seok-Min; Lee, In-Jung

    2016-01-01

    Nicotiana otophora is a wild parental species of Nicotiana tabacum, an interspecific hybrid of Nicotiana tomentosiformis and Nicotiana sylvestris. However, N. otophora is least understood as an alternative paternal donor. Here, we compared the fully assembled chloroplast (cp) genome of N. otophora and with those of closely related species. The analysis showed a cp genome size of 156,073 bp and exhibited a typical quadripartite structure, which contains a pair of inverted repeats separated by small and large single copies, containing 163 representative genes, with 165 microsatellites distributed unevenly throughout the genome. Comparative analysis of a gene with known function across Nicotiana species revealed 76 protein-coding sequences, 20 tRNA sequences, and 3 rRNA sequence shared between the cp genomes. The analysis revealed that N. otophora is a sister species to N. tomentosiformis within the Nicotiana genus, and Atropha belladonna and Datura stramonium are their closest relatives. These findings provide a valuable analysis of the complete N. otophora cp genome, which can identify species, elucidate taxonomy, and reconstruct the phylogeny of genus Nicotiana. PMID:27379132

  16. Reactions of Nicotiana species to inoculation with monopartite and bipartite begomoviruses

    PubMed Central

    2011-01-01

    Background Some Nicotiana species are widely used as experimental hosts for plant viruses. Nicotiana species differ in ploidy levels, chromosome numbers and have diverse geographical origins. Thus, these species are useful model systems to investigate virus-host interactions, co-evolution of pathogens and hosts and the effects of ploidy level on virus resistance/susceptibility. Results Here we have studied the responses of seven Nicotiana species to inoculation with Cotton leaf curl Multan virus (CLCuMV), a monopartite begomovirus, and Tomato leaf curl New Delhi virus (ToLCNDV), a bipartite begomovirus, both from the Indian subcontinent. All Nicotiana species supported the replication of both begomoviruses in inoculated leaves. However, only three Nicotiana species, namely N. benthamiana, N. tabacum and N. sylvestris showed symptoms when inoculated with ToLCNDV, while N. benthamiana was the only species that developed leaf curl symptoms when inoculated with CLCuMV. CLCuMV accumulated to detectable levels in N. tabacum, but plants remained asymptomatic. A previously identified mutation of RNA dependent RNA polymerase 1 was shown to be present only in N. benthamiana. The finding is in line with earlier results showing that the susceptibility of this species to a diverse range of plant viruses correlates with a defective RNA silencing-mediated host defense. Conclusions The results presented show that individual Nicotiana species respond differently to inoculation with begomoviruses. The inability of begomoviruses to systemically infect several Nicotiana species is likely due to inhibition of virus movement, rather than replication, and thus provides a novel model to study virus-host interactions in resistant/susceptible hosts. PMID:22011413

  17. Recombinant protein production in a variety of Nicotiana hosts: a comparative analysis.

    PubMed

    Conley, Andrew J; Zhu, Hong; Le, Linda C; Jevnikar, Anthony M; Lee, Byong H; Brandle, Jim E; Menassa, Rima

    2011-05-01

    Although many different crop species have been used to produce a wide range of vaccines, antibodies, biopharmaceuticals and industrial enzymes, tobacco has the most established history for the production of recombinant proteins. To further improve the heterologous protein yield of tobacco platforms, transient and stable expression of four recombinant proteins (i.e. human erythropoietin and interleukin-10, an antibody against Pseudomonas aeruginosa, and a hyperthermostable α-amylase) was evaluated in numerous species and cultivars of Nicotiana. Whereas the transient level of recombinant protein accumulation varied significantly amongst the different Nicotiana plant hosts, the variety of Nicotiana had little practical impact on the recombinant protein concentration in stable transgenic plants. In addition, this study examined the growth rate, amount of leaf biomass, total soluble protein levels and the alkaloid content of the various Nicotiana varieties to establish the best plant platform for commercial production of recombinant proteins. Of the 52 Nicotiana varieties evaluated, Nicotiana tabacum (cv. I 64) produced the highest transient concentrations of recombinant proteins, in addition to producing a large amount of biomass and a relatively low quantity of alkaloids, probably making it the most effective plant host for recombinant protein production.

  18. A distinct endogenous pararetrovirus family in Nicotiana tomentosiformis, a diploid progenitor of polyploid tobacco.

    PubMed

    Gregor, Wolfgang; Mette, M Florian; Staginnus, Christina; Matzke, Marjori A; Matzke, Antonius J M

    2004-03-01

    A distinct endogenous pararetrovirus (EPRV) family corresponding to a previously unknown virus has been identified in the genome of Nicotiana tomentosiformis, a diploid ancestor of allotetraploid tobacco (Nicotiana tabacum). The putative virus giving rise to N. tomentosiformis EPRVs (NtoEPRVs) is most similar to tobacco vein clearing virus, an episomal form of a normally silent EPRV family in Nicotiana glutinosa; it is also related to a putative virus giving rise to the NsEPRV family in Nicotiana sylvestris (the second diploid progenitor of tobacco) and in the N. sylvestris fraction of the tobacco genome. The copy number of NtoEPRVs is significantly higher in N. tomentosiformis than in tobacco. This suggests that after the polyploidization event, many copies were lost from the polyploid genome or were accumulated specifically in the diploid genome. By contrast, the copy number of NsEPRVs has remained constant in N. sylvestris and tobacco, indicating that changes have occurred preferentially in the NtoEPRV family during evolution of the three Nicotiana species. NtoEPRVs are often flanked by Gypsy retrotransposon-containing plant DNA. Although the mechanisms of NtoEPRV integration, accumulation, and/or elimination are unknown, these processes are possibly linked to retrotransposon activity.

  19. A tomato mutant that shows stunting, wilting, progressive necrosis and constitutive expression of defence genes contains a recombinant Hcr9 gene encoding an autoactive protein.

    PubMed

    Barker, Claire L; Talbot, Stephen J; Jones, Jonathan D G; Jones, David A

    2006-05-01

    The tomato Cf-9 gene confers resistance to races of the leaf mould fungus Cladosporium fulvum that carry the Avr9 avirulence gene. Cf-9 resides at a locus containing five paralogous genes and was isolated by transposon tagging using a modified maize Dissociation (Ds) element. The tagging experiment generated an allelic series of Ds-induced mutations of Cf-9, most of which were wild type in appearance. However, one mutant, designated M205, showed stunted growth, wilting, progressive leaf chlorosis and necrosis and constitutive expression of defence genes. The phenotype of M205 was caused by a semidominant, Avr9-independent mutation that co-segregated with a Ds element insertion at the Cf-9 locus. Molecular genetic analysis indicated that the Cf-9 locus of M205 had undergone recombination, generating a chimeric gene, designated Hcr9-M205, that comprised an in-frame fusion between the 5' coding region of the Cf-9 paralogue, Hcr9-9A, and the 3' coding region of Cf-9. The presence of a possible excision footprint adjacent to the junction between Hcr9-9A and Cf-9, and a Ds insertion at the homologous position in the downstream paralogue Hcr9-9D, is consistent with recombination between Hcr9-9A and Cf-9 promoted by transposition of Ds from Cf-9 into Hcr9-9D. Agrobacterium tumefaciens-mediated transient expression of Hcr9-M205 in Nicotiana tabacum caused chlorosis and the accumulation of defence gene transcripts, indicating that the protein encoded by this novel Hcr9 gene is autoactive.

  20. Rhizosecretion improves the production of Cyanovirin-N in Nicotiana tabacum through simplified downstream processing.

    PubMed

    Madeira, Luisa M; Szeto, Tim H; Ma, Julian K-C; Drake, Pascal M W

    2016-07-01

    Rhizosecretion has many advantages for the production of recombinant pharmaceuticals, notably facile downstream processing from hydroponic medium. The aim of this study was to increase yields of the HIV microbicide candidate, Cyanovirin-N (CV-N), obtained using this production platform and to develop a simplified methodology for its downstream processing from hydroponic medium. Placing hydroponic cultures on an orbital shaker more than doubled the concentration of CV-N in the hydroponic medium compared to plants which remained stationary, reaching a maximum of approximately 20μg/ml in one week, which is more than 3 times higher than previously reported yields. The protein composition of the hydroponic medium, the rhizosecretome, was characterised in plants cultured with or without the plant growth regulator alpha-napthaleneacetic acid by LC-ESI-MS/MS, and CV-N was the most abundant protein. The issue of large volumes in the rhizosecretion system was addressed by using ion exchange chromatography to concentrate CV-N and partially remove impurities. The semi-purified CV-N was demonstrated to bind to HIV gp120 in an ELISA and to neutralise HIVBa-L with an IC50 of 6nM in a cell-based assay. Rhizosecretion is therefore a practicable and inexpensive method for the production of functional CV-N.

  1. Titanium dioxide nanoparticles affect the growth and microRNA expression of tobacco (Nicotiana tabacum).

    PubMed

    Frazier, Taylor P; Burklew, Caitlin E; Zhang, Baohong

    2014-03-01

    Titanium dioxide (TiO(2)) is one of the most widely used pigments in the world. Due to its heavy use in industry and daily life, such as food additives, cosmetics, pharmaceuticals, and paints, many residues are released into the environment and currently TiO(2) nanoparticles are considered an emerging environmental contaminant. Although several studies have shown the effect of TiO(2) nanoparticles on a wide range of organisms including bacteria, algae, plankton, fish, mice, and rats, little research has been performed on land plants. In this study, we investigated the effect of TiO(2) nanoparticles on the growth, development, and gene expression of tobacco, an important economic and agricultural crop in the southeastern USA as well as around the world. We found that TiO(2) nanoparticles significantly inhibited the germination rates, root lengths, and biomasses of tobacco seedlings after 3 weeks of exposure to 0.1, 1, 2.5, and 5 % TiO(2) nanoparticles and that overall growth and development of the tobacco seedlings significantly decreased as TiO(2) nanoparticle concentrations increased. Overall, tobacco roots were the most sensitive to TiO(2) nanoparticle exposure. Nano-TiO(2) also significantly influenced the expression profiles of microRNAs (miRNAs), a recently discovered class of small endogenous noncoding RNAs (∼20-22 nt) that are considered important gene regulators and have been shown to play an important role in plant development as well as plant tolerance to abiotic stresses such as drought, salinity, cold, and heavy metal. Low concentrations (0.1 and 1 %) of TiO(2) nanoparticles dramatically induced miRNA expression in tobacco seedlings with miR395 and miR399 exhibiting the greatest fold changes of 285-fold and 143-fold, respectively. The results of this study show that TiO(2) nanoparticles have a negative impact on tobacco growth and development and that miRNAs may play an important role in tobacco response to heavy metals/nanoparticles by regulating gene expression.

  2. (E)-β-farnesene synthase genes affect aphid (Myzus persicae) infestation in tobacco (Nicotiana tabacum).

    PubMed

    Yu, Xiudao; Jones, Huw D; Ma, Youzhi; Wang, Genping; Xu, Zhaoshi; Zhang, Baoming; Zhang, Yongjun; Ren, Guangwei; Pickett, John A; Xia, Lanqin

    2012-03-01

    Aphids are major agricultural pests which cause significant yield losses of the crop plants each year. (E)-β-farnesene (EβF) is the alarm pheromone involved in the chemical communication between aphids and particularly in the avoidance of predation. In the present study, two EβF synthase genes were isolated from sweet wormwood and designated as AaβFS1 and AaβFS2, respectively. Overexpression of AaβFS1 or AaβFS2 in tobacco plants resulted in the emission of EβF ranging from 1.55 to 4.65 ng/day/g fresh tissues. Tritrophic interactions involving the peach aphids (Myzus persicae), predatory lacewings (Chrysopa septempunctata) demonstrated that the transgenic tobacco expressing AaβFS1 and AaβFS2 could repel peach aphids, but not as strongly as expected. However, AaβFS1 and AaβFS2 lines exhibited strong and statistically significant attraction to lacewings. Further experiments combining aphids and lacewing larvae in an octagon arrangement showed transgenic tobacco plants could repel aphids and attract lacewing larvae, thus minimizing aphid infestation. Therefore, we demonstrated a potentially valuable strategy of using EβF synthase genes from sweet wormwood for aphid control in tobacco or other economic important crops in an environmentally benign way.

  3. Overexpression of mitochondrial uncoupling protein 1 (UCP1) induces a hypoxic response in Nicotiana tabacum leaves

    PubMed Central

    Barreto, Pedro; Okura, Vagner; Pena, Izabella A.; Maia, Renato; Maia, Ivan G.; Arruda, Paulo

    2016-01-01

    Mitochondrial uncoupling protein 1 (UCP1) decreases reactive oxygen species production under stress conditions by uncoupling the electrochemical gradient from ATP synthesis. This study combined transcriptome profiling with experimentally induced hypoxia to mechanistically dissect the impact of Arabidopsis thaliana UCP1 (AtUCP1) overexpression in tobacco. Transcriptomic analysis of AtUCP1-overexpressing (P07) and wild-type (WT) plants was carried out using RNA sequencing. Metabolite and carbohydrate profiling of hypoxia-treated plants was performed using 1H-nuclear magnetic resonance spectroscopy and high-performance anion-exchange chromatography with pulsed amperometric detection. The transcriptome of P07 plants revealed a broad induction of stress-responsive genes that were not strictly related to the mitochondrial antioxidant machinery, suggesting that overexpression of AtUCP1 imposes a strong stress response within the cell. In addition, transcripts that mapped into carbon fixation and energy expenditure pathways were broadly altered. It was found that metabolite markers of hypoxic adaptation, such as alanine and tricarboxylic acid intermediates, accumulated in P07 plants under control conditions at similar rates to WT plants under hypoxia. These findings indicate that constitutive overexpression of AtUCP1 induces a hypoxic response. The metabolites that accumulated in P07 plants are believed to be important in signalling for an improvement in carbon assimilation and induction of a hypoxic response. Under these conditions, mitochondrial ATP production is less necessary and fermentative glycolysis becomes critical to meet cell energy demands. In this scenario, the more flexible energy metabolism along with an intrinsically activated hypoxic response make these plants better adapted to face several biotic and abiotic stresses. PMID:26494730

  4. Isonitrosoacetophenone Drives Transcriptional Reprogramming in Nicotiana tabacum Cells in Support of Innate Immunity and Defense

    PubMed Central

    Djami-Tchatchou, Arnaud T.; Maake, Mmapula P.; Piater, Lizelle A.; Dubery, Ian A.

    2015-01-01

    Plants respond to various stress stimuli by activating broad-spectrum defense responses both locally as well as systemically. As such, identification of expressed genes represents an important step towards understanding inducible defense responses and assists in designing appropriate intervention strategies for disease management. Genes differentially expressed in tobacco cell suspensions following elicitation with isonitrosoacetophenone (INAP) were identified using mRNA differential display and pyro-sequencing. Sequencing data produced 14579 reads, which resulted in 198 contigs and 1758 singletons. Following BLAST analyses, several inducible plant defense genes of interest were identified and classified into functional categories including signal transduction, transcription activation, transcription and protein synthesis, protein degradation and ubiquitination, stress-responsive, defense-related, metabolism and energy, regulation, transportation, cytoskeleton and cell wall-related. Quantitative PCR was used to investigate the expression of 17 selected target genes within these categories. Results indicate that INAP has a sensitising or priming effect through activation of salicylic acid-, jasmonic acid- and ethylene pathways that result in an altered transcriptome, with the expression of genes involved in perception of pathogens and associated cellular re-programming in support of defense. Furthermore, infection assays with the pathogen Pseudomonas syringae pv. tabaci confirmed the establishment of a functional anti-microbial environment in planta. PMID:25658943

  5. The influence of light quality on the accumulation of flavonoids in tobacco (Nicotiana tabacum L.) leaves.

    PubMed

    Fu, Bo; Ji, Xiaoming; Zhao, Mingqin; He, Fan; Wang, Xiaoli; Wang, Yiding; Liu, Pengfei; Niu, Lu

    2016-09-01

    Flavonoids are important secondary metabolites in plants regulated by the environment. To analyze the effect of light quality on the accumulation of flavonoids, we performed a rapid analysis of flavonoids in extracts of tobacco leaves using UHPLC-QTOF. A total of 12 flavonoids were detected and identified in tobacco leaves, which were classified into flavonoid methyl derivatives and flavonoid glycoside derivatives according to the groups linked to the flavonoid core. Correlation analysis was further conducted to investigate the effect of different wavelengths of light on their accumulation. The content of flavonoid methyl derivatives was positively correlated with the proportions of far-red light (FR; 716-810nm) and near-infrared light (NIR; 810-2200nm) in the sunlight spectrum and negatively correlated with the proportion of ultraviolet (UV-A; 350-400nm) and the red/far-red ratio (R/FR). By contrast, the content of flavonoid glycoside derivatives was positively correlated with the proportion of UV-A and the R/FR, and negatively correlated with FR and NIR. The results indicated that light quality with higher proportions of FR and NIR increases the activity of flavonoid methyltransferases but suppresses the activity of flavonoid glycoside transferases. While a high proportion of UV-A and a high R/FR can increase flavonoid glycoside transferase activity but suppress flavonoid methyltransferase activity.

  6. Short polyhistidine peptides penetrate effectively into Nicotiana tabacum-cultured cells and Saccharomyces cerevisiae cells.

    PubMed

    Kimura, Sayaka; Kawano, Tsuyoshi; Iwasaki, Takashi

    2017-01-01

    The polyhistidine peptides (PHPs) have been previously reported as novel cell-penetrating peptides and are efficiently internalized into mammal cells; however, penetration of PHPs into other cell types is unknown. In this study, the cellular uptake of PHPs in plant and yeast cells was found to be dependent on the number of histidines, and short PHPs (H6-H10 peptides) showed effective internalization. The H8 peptide showed the highest cell-penetrating capacity and localized to vacuoles in plant and yeast cells. Low-temperature conditions inhibited significantly the cellular uptake of short PHPs by both cells. However, net charge neutralization of PHPs also completely inhibited cellular uptake by plant cells, but not by yeast cells. These results indicate that short PHPs penetrate effectively into plant and yeast cells by similar mechanism with the exception of net charge dependency. The findings show the short PHPs are promising candidates for new delivery tools into plant and yeast cells.

  7. Dynamic metabonomic responses of tobacco (Nicotiana tabacum) plants to salt stress.

    PubMed

    Zhang, Jingtao; Zhang, Yong; Du, Yuanyuan; Chen, Shiyun; Tang, Huiru

    2011-04-01

    Metabolic responses are important for plant adaptation to osmotic stresses. To understand the dosage and duration dependence of salinity effects on plant metabolisms, we analyzed the metabonome of tobacco plants and its dynamic responses to salt treatments using NMR spectroscopy in combination with multivariate data analysis. Our results showed that the tobacco metabonome was dominated by 40 metabolites including organic acids/bases, amino acids, carbohydrates and choline, pyrimidine, and purine metabolites. A dynamic trajectory was clearly observable for the tobacco metabonomic responses to the dosage of salinity. Short-term low-dose salt stress (50 mM NaCl, 1 day) caused metabolic shifts toward gluconeogenesis with depletion of pyrimidine and purine metabolites. Prolonged salinity with high-dose salt (500 mM NaCl) induced progressive accumulation of osmolytes, such as proline and myo-inositol, and changes in GABA shunt. Such treatments also promoted the shikimate-mediated secondary metabolisms with enhanced biosynthesis of aromatic amino acids. Therefore, salinity caused systems alterations in widespread metabolic networks involving transamination, TCA cycle, gluconeogenesis/glycolysis, glutamate-mediated proline biosynthesis, shikimate-mediated secondary metabolisms, and the metabolisms of choline, pyrimidine, and purine. These findings provided new insights for the tobacco metabolic adaptation to salinity and demonstrated the NMR-based metabonomics as a powerful approach for understanding the osmotic effects on plant biochemistry.

  8. Expression of recombinant antibody (single chain antibody fragment) in transgenic plant Nicotiana tabacum cv. Xanthi.

    PubMed

    Dobhal, S; Chaudhary, V K; Singh, A; Pandey, D; Kumar, A; Agrawal, S

    2013-12-01

    Plants offer an alternative inexpensive and convenient technology for large scale production of recombinant proteins especially recombinant antibodies (plantibodies). In this paper, we describe the expression of a model single chain antibody fragment (B6scFv) in transgenic tobacco. Four different gene constructs of B6scFv with different target signals for expression in different compartments of a tobacco plant cell with and without endoplasmic reticulum (ER) retention signal were used. Agrobacterium mediated plant transformation of B6scFv gene was performed with tobacco leaf explants and the gene in regenerated plants was detected using histochemical GUS assay and PCR. The expression of B6scFv gene was detected by western blotting and the recombinant protein was purified from putative transgenic tobacco plants using metal affinity chromatography. The expression level of recombinant protein was determined by indirect enzyme-linked immunosorbent assay. The highest accumulation of protein was found up to 3.28 % of the total soluble protein (TSP) in plants expressing B6scFv 1003 targeted to the ER, and subsequently expression of 2.9 % of TSP in plants expressing B6scFv 1004 (with target to apoplast with ER retention signal). In contrast, lower expression of 0.78 and 0.58 % of TSP was found in plants expressing antibody fragment in cytosol and apoplast, without ER retention signal. The described method/system could be used in the future for diverse applications including expression of other recombinant molecules in plants for immunomodulation, obtaining pathogen resistance against plant pathogens, altering metabolic pathways and also for the expression of different antibodies of therapeutic and diagnostic uses.

  9. Inhibition of Trehalose Breakdown Increases New Carbon Partitioning into Cellulosic Biomass in Nicotiana tabacum

    SciTech Connect

    Best, F.M.; Ferrieri, R.; Best, F.M.; Koenig, K.; McDonald, K.; Schueller, M.J.; Rogers, A.; Ferrieri, R.A.

    2011-01-18

    Validamycin A was used to inhibit in vivo trehalase activity in tobacco enabling the study of subsequent changes in new C partitioning into cellulosic biomass and lignin precursors. After 12-h exposure to treatment, plants were pulse labeled using radioactive {sup 11}CO{sub 2}, and the partitioning of isotope was traced into [{sup 11}C]cellulose and [{sup 11}C]hemicellulose, as well as into [{sup 11}C]phenylalanine, the precursor for lignin. Over this time course of treatment, new carbon partitioning into hemicellulose and cellulose was increased, while new carbon partitioning into phenylalanine was decreased. This trend was accompanied by a decrease in phenylalanine ammonia-lyase activity. After 4 d of exposure to validamycin A, we also measured leaf protein content and key C and N metabolite pools. Extended treatment increased foliar cellulose and starch content, decreased sucrose, and total amino acid and nitrate content, and had no effect on total protein.

  10. Osmotic Adjustment of Cultured Tobacco Cells (Nicotiana tabacum var. Samsum) Grown on Sodium Chloride 1

    PubMed Central

    Heyser, James W.; Nabors, Murray W.

    1981-01-01

    Tobacco cell cultures (var. Samsum) were grown on increasing levels of NaCl to select variants for increased salt tolerance. The osmotic adjustment of NaCl-adapted and nonadapted cell lines was studied. Both cell lines were grown on modified Linsmaier and Skoog medium with or without NaCl. Few differences were found in the response of adapted and nonadapted lines to NaCl. The concentrations of sugars, Na+, Cl−, and NO3− were identical in the cells and medium. Potassium and amino acids were accumulated by the cells. All of the above solutes accounted for 80 to 90% of the osmotic potential for both cell lines when grown on basal medium with or without NaCl. The osmotic potential of growing cells was always 1 to 3 bars more negative than that of the medium. During the first 10 days culture, the cells hydrolyzed the 117 millimolar sucrose present in the fresh media, and the media became more negative by 3 bars. Growing cells absorbed and metabolized the sugars, NH4+, and NO3− during the next 25 days, and the osmotic potential of the media and cells became less negative. The addition of 130 millimolar NaCl made the media and cells osmotically more negative by 6 bars throughout the growth cycle, as compared with cells growing on basal medium. The efflux of cellular solutes during distilled H2O washes was resolved into two components. The fast component (0.6 to 1.7 minutes half-time) included solutes of the free space and cytoplasm, whereas the slow component (1.6 to 4.9 hours half-time) represented the vacuolar solutes. Sodium and Cl− were present in the vacuole. No differences were observed in the solute efflux between the adapted and nonadapted cell lines. PMID:16661743

  11. Characterisation of detergent-insoluble membranes in pollen tubes of Nicotiana tabacum (L.)

    PubMed Central

    Moscatelli, Alessandra; Gagliardi, Assunta; Maneta-Peyret, Lilly; Bini, Luca; Stroppa, Nadia; Onelli, Elisabetta; Landi, Claudia; Scali, Monica; Idilli, Aurora Irene; Moreau, Patrick

    2015-01-01

    ABSTRACT Pollen tubes are the vehicle for sperm cell delivery to the embryo sac during fertilisation of Angiosperms. They provide an intriguing model for unravelling mechanisms of growing to extremes. The asymmetric distribution of lipids and proteins in the pollen tube plasma membrane modulates ion fluxes and actin dynamics and is maintained by a delicate equilibrium between exocytosis and endocytosis. The structural constraints regulating polarised secretion and asymmetric protein distribution on the plasma membrane are mostly unknown. To address this problem, we investigated whether ordered membrane microdomains, namely membrane rafts, might contribute to sperm cell delivery. Detergent insoluble membranes, rich in sterols and sphingolipids, were isolated from tobacco pollen tubes. MALDI TOF/MS analysis revealed that actin, prohibitins and proteins involved in methylation reactions and in phosphoinositide pattern regulation are specifically present in pollen tube detergent insoluble membranes. Tubulins, voltage-dependent anion channels and proteins involved in membrane trafficking and signalling were also present. This paper reports the first evidence of membrane rafts in Angiosperm pollen tubes, opening new perspectives on the coordination of signal transduction, cytoskeleton dynamics and polarised secretion. PMID:25701665

  12. Nicotiana Roots Recruit Rare Rhizosphere Taxa as Major Root-Inhabiting Microbes.

    PubMed

    Saleem, Muhammad; Law, Audrey D; Moe, Luke A

    2016-02-01

    Root-associated microbes have a profound impact on plant health, yet little is known about the distribution of root-associated microbes among different root morphologies or between rhizosphere and root environments. We explore these issues here with two commercial varieties of burley tobacco (Nicotiana tabacum) using 16S rRNA gene amplicon sequencing from rhizosphere soil, as well as from primary, secondary, and fine roots. While rhizosphere soils exhibited a fairly rich and even distribution, root samples were dominated by Proteobacteria. A comparison of abundant operational taxonomic units (OTUs) between rhizosphere and root samples indicated that Nicotiana roots select for rare taxa (predominantly Proteobacteria, Verrucomicrobia, Actinobacteria, Bacteroidetes, and Acidobacteria) from their corresponding rhizosphere environments. The majority of root-inhabiting OTUs (~80 %) exhibited habitat generalism across the different root morphological habitats, although habitat specialists were noted. These results suggest a specific process whereby roots select rare taxa from a larger community.

  13. Effects of Host Resistance and Temperature on Development of Globodera tabacum solanacearum

    PubMed Central

    Wang, J.; Johnson, C. S.; Eisenback, J. D.

    2001-01-01

    Penetration and development of juveniles of tobacco cyst nematode (Globodera tabacum solanacearum) on a resistant (NC567) and a susceptible (K326) cultivar of flue-cured tobacco (Nicotiana tabacum L.) were determined in root zone chamber experiments. More vermiform juveniles developed into a swollen shape at 22, 27, and 31 °C than at 17 °C. Development of flask-shaped nematodes appeared to be similar across tested temperatures (17, 22, 27, and 31 °C). General patterns of penetration and development of juveniles in both resistant and susceptible cultivars were similar under all temperatures tested. More vermiform, swollen, and flask-shaped nematodes were found in roots of K326 than in those of NC567. Development from swollen to flaskshaped nematodes appeared to be similar between the two cultivars, although more vermiform juveniles developed into swollen nematodes on K326 than on NC567. Differences in resistance between the two cultivars remained stable across tested temperatures. PMID:19266009

  14. Indole-3-acetic Acid Synthesis in Tumorous and Nontumorous Species of Nicotiana 1

    PubMed Central

    Liu, Shih-Tung; Katz, Charles D.; Knight, C. Arthur

    1978-01-01

    The synthesis of indole-3-acetic acid (IAA) in the enzyme extracts of Nicotiana glauca, Nicotiana langsdorffii, their F1 hybrid, their amphidiploid hybrid, and the nontumorous mutant of the hybrid was investigated. Tryptamine, a possible precursor of IAA biosynthesis in Nicotiana tabacum, was not found in the callus tissue of N. glauca, N. langsdorffii, and their F1 hybrid. In petiole slices, the synthesis of IAA progressively increased during 5 hours of incubation in [14C]tryptophan. The rate of synthesis was about equal in the hybrid and N. langsdorffii but lower in N. glauca on either a cell or fresh weight basis. It was also found that tryptophan was about 25 times more efficient than tryptamine in promoting synthesis of IAA in petiole slices. It was found that indoleacetaldehyde oxidase, indoleacetaldehyde reductase, and tryptophan aminotransferase activities were present in all of the species examined; however, tryptophan decarboxylase activity was not found. The tryptophan aminotransferase activity in N. glauca, N. langsdorffii, and the nontumorous mutant required α-ketoglutaric acid and pyridoxal 5-phosphate whereas the addition of pyridoxal 5-phosphate seemed not to increase the enzyme activity in tumor plants. The tryptophan aminotransferase in the amphidiploid hybrid was partially purified by acetone precipitation. The enzyme activity had a temperature optimum at 49 C and a pH optimum at 8.9. It is suggested that there is an indolepyruvic acid pathway in the synthesis of IAA in the Nicotiana species examined. PMID:16660376

  15. Regulation of catalase activity in leaves of Nicotiana sylvestris by high CO sub 2

    SciTech Connect

    Havir, E.A.; McHale, N.A. )

    1989-03-01

    The effect of high CO{sub 2} (1% CO{sub 2}/21% O{sub 2}) on the activity of specific forms of catalase (CAT-1, -2, and -3) in seedling leaves of tobacco (Nicotiana sylvestris, Nicotiana tabacum) was examined. In high CO{sub 2} total catalase activity decreased by 50% in the first 2 days, followed by a more gradual decline in the next 4 days. The loss of total activity resulted primarily from a decrease in CAT-1 catalase. In contrast, the activity of CAT-3 catalase, a form with enhanced peroxidatic activity, increased 3-fold in high CO{sub 2} relative to air controls after 4 days. Short-term exposure to high CO{sub 2} indicated that the 50% loss of total activity occurs in the firs 12 hours. Catalase levels increased to normal within 12 hours after seedlings were returned to air. When seedlings were transferred to air after prolonged exposure to high CO{sub 2} (13 days), the levels of CAT-1 catalase were partially restored while CAT-3 remained at its elevated level. Levels of superoxide dismutase activity and those of several peroxisomal enzymes were not affected by high CO{sub 2}. Total catalase levels did not decline when seedlings were exposed to atmospheres of 0.04% CO{sub 2}/5% O{sub 2} or 0.04% CO{sub 2}/1% O{sub 2}, indicating that regulation of catalase in high CO{sub 2} is not related directly to suppression of photorespiration. Antibodies prepared against CAT-1 catalase from N. tabacum reacted strongly against CAT-1 catalase from both N. sylvestris and N. tabacum but not against CAT-3 catalase from either species.

  16. Predisposition of Broadleaf Tobacco to Fusarium Wilt by Early Infection with Globodera tabacum tabacum or Meloidogyne hapla

    PubMed Central

    LaMondia, J. A.

    1992-01-01

    In greenhouse experiments, broadleaf tobacco plants were inoculated with tobacco cyst (Globodera tabacum tabacum) or root-knot (Meloidogyne hapla) nematodes 3, 2, or 1 week before or at the same time as Fusarium oxysporum. Plants infected with nematodes prior to fungal inoculation had greater Fusarium wilt incidence and severity than those simultaneously inoculated. G. t. tabacum increased wilt incidence and severity more than did M. hapla. Mechanical root wounding within 1 week of F. oxysporum inoculation increased wilt severity. In field experiments, early-season G. t. tabacum control by preplant soil application of oxamyl indirectly limited the incidence and severity of wilt. Wilt incidence was 48%, 23%, and 8% in 1989 and 64%, 60%, and 19% in 1990 for 0.0, 2.2, and 6.7 kg oxamyl/ha, respectively. Early infection of tobacco by G. t. tabacum predisposed broadleaf tobacco to wilt by F. oxysporum. PMID:19283018

  17. The effect of polyploidy and hybridization on the evolution of floral colour in Nicotiana (Solanaceae)

    PubMed Central

    McCarthy, Elizabeth W.; Arnold, Sarah E. J.; Chittka, Lars; Le Comber, Steven C.; Verity, Robert; Dodsworth, Steven; Knapp, Sandra; Kelly, Laura J.; Chase, Mark W.; Baldwin, Ian T.; Kovařík, Aleš; Mhiri, Corinne; Taylor, Lin; Leitch, Andrew R.

    2015-01-01

    Background and Aims Speciation in angiosperms can be accompanied by changes in floral colour that may influence pollinator preference and reproductive isolation. This study investigates whether changes in floral colour can accompany polyploid and homoploid hybridization, important processes in angiosperm evolution. Methods Spectral reflectance of corolla tissue was examined for 60 Nicotiana (Solanaceae) accessions (41 taxa) based on spectral shape (corresponding to pigmentation) as well as bee and hummingbird colour perception in order to assess patterns of floral colour evolution. Polyploid and homoploid hybrid spectra were compared with those of their progenitors to evaluate whether hybridization has resulted in floral colour shifts. Key Results Floral colour categories in Nicotiana seem to have arisen multiple times independently during the evolution of the genus. Most younger polyploids displayed an unexpected floral colour, considering those of their progenitors, in the colour perception of at least one pollinator type, whereas older polyploids tended to resemble one or both of their progenitors. Conclusions Floral colour evolution in Nicotiana is weakly constrained by phylogeny, and colour shifts do occur in association with both polyploid and homoploid hybrid divergence. Transgressive floral colour in N. tabacum has arisen by inheritance of anthocyanin pigmentation from its paternal progenitor while having a plastid phenotype like its maternal progenitor. Potentially, floral colour evolution has been driven by, or resulted in, pollinator shifts. However, those polyploids that are not sympatric (on a regional scale) with their progenitor lineages are typically not divergent in floral colour from them, perhaps because of a lack of competition for pollinators. PMID:25979919

  18. Recombinant protein expression in Nicotiana.

    PubMed

    Matoba, Nobuyuki; Davis, Keith R; Palmer, Kenneth E

    2011-01-01

    Recombinant protein pharmaceuticals are now widely used in treatment of chronic diseases, and several recombinant protein subunit vaccines are approved for human and veterinary use. With growing demand for complex protein pharmaceuticals, such as monoclonal antibodies, manufacturing capacity is becoming limited. There is increasing need for safe, scalable, and economical alternatives to mammalian cell culture-based manufacturing systems, which require substantial capital investment for new manufacturing facilities. Since a seminal paper reporting immunoglobulin expression in transgenic plants was published in 1989, there have been many technological advances in plant expression systems to the present time where production of proteins in leaf tissues of nonfood crops such as Nicotiana species is considered a viable alternative. In particular, transient expression systems derived from recombinant plant viral vectors offer opportunities for rapid expression screening, construct optimization, and expression scale-up. Extraction of recombinant proteins from Nicotiana leaf tissues can be achieved by collection of secreted protein fractions, or from a total protein extract after grinding the leaves with buffer. After separation from solids, the major purification challenge is contamination with elements of the photosynthetic complex, which can be solved by application of a variety of facile and proven strategies. In conclusion, the technologies required for safe, efficient, scalable manufacture of recombinant proteins in Nicotiana leaf tissues have matured to the point where several products have already been tested in phase I clinical trials and will soon be followed by a rich pipeline of recombinant vaccines, microbicides, and therapeutic proteins.

  19. Diverse opportunities in defence

    NASA Astrophysics Data System (ADS)

    Brown, Gareth

    2016-08-01

    Working at the UK's defence laboratory gives Gareth Brown the ability to apply his physics and mathematics knowledge to real-world applications - and not necessarily in the ways you might expect. This article is Crown copyright

  20. Defence Reporter. Spring 2011

    DTIC Science & Technology

    2011-01-01

    of a series of services and products produced by ATHENA to keep readers up -to- date with the latest developments in key areas of defence science...the MOD’s ATHENA Collection. Defence Reporter is available by subscription. To sign up for this free service, please send an e-mail with your full...for the oral route. This study was set up lo enable some confirmation of published LD50 information of orally dosed ricin but also to enable some

  1. Stable genetic transformation of intact Nicotiana cells by the particle bombardment process

    PubMed Central

    Klein, Theodore M.; Harper, Elisabeth C.; Svab, Zora; Sanford, John C.; Fromm, Michael E.; Maliga, Pal

    1988-01-01

    We show that the genetic transformation of Nicotiana tabacum can be achieved by bombarding intact cells and tissues with DNA-coated particles. Leaves or suspension culture cells were treated with tungsten microprojectiles carrying plasmid DNA containing a neomycin phosphotransferase gene. Callus harboring the foreign gene was recovered from the bombarded tissue by selection on medium containing kanamycin. Kanamycin-resistant plants have subsequently been regenerated from the callus derived from leaves. Transient expression of an introduced β-glucuronidase gene was used to assess the efficiency of DNA delivery by microprojectiles. The frequency of cells that were stably transformed with the neomycin phosphotransferase gene was a few percent of the cells that transiently expressed the β-glucuronidase gene. These results show that gene transfer by high-velocity microprojectiles is a rapid and direct means for transforming intact plant cells and tissues that eliminates the need for production of protoplasts or infection by Agrobacterium. Images PMID:16593993

  2. The Evolutionary Fate of the Horizontally Transferred Agrobacterial Mikimopine Synthase Gene in the Genera Nicotiana and Linaria

    PubMed Central

    Talianova, Martina; Vyskot, Boris

    2014-01-01

    Few cases of spontaneously horizontally transferred bacterial genes into plant genomes have been described to date. The occurrence of horizontally transferred genes from the T-DNA of Agrobacterium rhizogenes into the plant genome has been reported in the genus Nicotiana and in the species Linaria vulgaris. Here we compare patterns of evolution in one of these genes (a gene encoding mikimopine synthase, mis) following three different events of horizontal gene transfer (HGT). As this gene plays an important role in Agrobacterium, and there are known cases showing that genes from pathogens can acquire plant protection function, we hypothesised that in at least some of the studied species we will find signs of selective pressures influencing mis sequence. The mikimopine synthase (mis) gene evolved in a different manner in the branch leading to Nicotiana tabacum and N. tomentosiformis, in the branch leading to N. glauca and in the genus Linaria. Our analyses of the genus Linaria suggest that the mis gene began to degenerate soon after the HGT. In contrast, in the case of N. glauca, the mis gene evolved under significant selective pressures. This suggests a possible role of mikimopine synthase in current N. glauca and its ancestor(s). In N. tabacum and N. tomentosiformis, the mis gene has a common frameshift mutation that disrupted its open reading frame. Interestingly, our results suggest that in spite of the frameshift, the mis gene could evolve under selective pressures. This sequence may still have some regulatory role at the RNA level as suggested by coverage of this sequence by small RNAs in N. tabacum. PMID:25420106

  3. Transcriptomics assisted proteomic analysis of Nicotiana occidentalis infected by Candidatus Phytoplasma mali strain AT.

    PubMed

    Luge, Toni; Kube, Michael; Freiwald, Anja; Meierhofer, David; Seemüller, Erich; Sauer, Sascha

    2014-08-01

    Phytoplasmas are pathogenic bacteria within the class of Mollicutes, which are associated with more than 1000 plant diseases. In this study, we applied quantitative mass spectrometry to analyse affected pathways of the model plant tobacco (Nicotiana occidentalis) upon Candidatus Phytoplasma mali strain AT infection. Using tissue obtained from leaf midribs, 1466 plant-assigned proteins were identified. For 1019 of these proteins, we could reproducibly quantify the expression changes of infected versus noninfected plants, of which 157 proteins were up- and 173 proteins were downregulated. Differential expression took place in a number of pathways, among others strong downregulation of porphyrin and chlorophyll metabolism and upregulation of alpha-linolenic acid metabolism, which was consistent with observed increased levels of jasmonic acid, a key signal molecule of plant defence. Our data shed light on the molecular networks that are involved in defence of plants against phytoplasma infection and provide a resource for further studies.

  4. Some physiological aspects of nitrate reductase-deficient Nicotiana plumbaginifolia plants

    SciTech Connect

    Saux, C.; Morot-Gaudry, J.F.; Lemoine, Y.; Caboche, M.

    1986-04-01

    Chlorate-resistant Nicotiana plumbaginifolia (cv. Viviani) mutants were found to be defective in the nitrate reductase apoprotein (NR/sup -/ nia). Because they could not grow with nitrate as sole nitrogen source, they were cultivated as graftings on wild type Nicotiana tabacum. The grafts of NR/sup -/ plants were found to contain less malate but more amino acids, sugars and starch than the wild type. Moreover they were chlorotic, with a slight increase of the proportion of LH Chl a/b protein complexes and they exhibited a lowering of the efficiency of energy transfer between the light-harvesting complexes and the active centers. After /sup 14/CO/sub 2/ pulse and chase experiments. The total /sup 14/C incorporation of the mutant leaves was approximately 20% of that of the control. The NR/sup -/ leaves mainly accumulated /sup 14/C in the whole intermediates of the Calvin-cycle and in sucrose. In the most deficient NR leaves, chloroplasts were stuffed with large starch inclusions disorganizing the lamellar system.

  5. Consequence of absence of nitrate reductase activity on photosynthesis in Nicotiana plumbaginifolia plants

    SciTech Connect

    Saux, C.; Lemoine, Y.; Marion-Poll, A.; Valadier, M.H.; Deng, M.; Morot-Gaudry, J.F.

    1987-05-01

    Chlorate-resistant Nicotiana plumbaginifolia (cv Viviani) mutants were found to be deficient in the nitrate reductase apoprotein (NR/sup -/ nia). Because they could not grow with nitrate as sole nitrogen source, they were cultivated as graftings on wild-type Nicotiana tabacum plants. The grafts of mutant plants were chlorotic compared to the grafts of wild type. Mutant leaves did not accumulate nitrogen but contained less malate and more glutamine than wild leaves. They exhibited a slight increase of the proportion of the light-harvesting chlorophyll a/b protein complexes and a lowering of the efficiency of energy transfer between these complexes and the active centers. After a 3 second /sup 14/CO/sub 2/ pulse, the total /sup 14/C incorporation of the mutant leaves was approximately 20/sup 5/ of that of the control. The /sup 14/C was essentially recovered in ribulose bisphosphate in these plants. It was consistent with a decline of ribulose bisphosphate carboxylase activity observed in the mutant. After a 3 second /sup 14/CO/sub 2/ pulse followed by a 60 second chase with normal CO/sub 2/, /sup 14/C was mainly accumulated in starch which was labeled more in the mutant than in the wild type. These results confirm the observation that in the nitrate reductase deficient leaves, chloroplasts were loaded with large starch inclusions preceding disorganization of the photosynthetic apparatus.

  6. Alternative defence policy

    SciTech Connect

    Burt, G.

    1987-01-01

    This book considers key questions connected with the present crisis, questions such as Would conventional deterrence really be effective. Just what is the Labour Party's policy. How precisely might Britain be transformed into a non-aligned, non-military state. The future of British defence policy is an issue of major concern not just in Britain but throughout the world, especially in the United States where there are major anxieties in the Pentagon about what will happen if the Labour Party wins an election outright. British defence policy is currently in a state of crisis. The former position where a reasonably united establishment on one hand confronted nuclear disarmers on the other has been replaced by a position where a wide spectrum of different opinions is held not just by the peace movement and the opposition parties but by many people in the Conservative party and the military also.

  7. Dynamic changes in the distribution of a satellite homologous to intergenic 26-18S rDNA spacer in the evolution of Nicotiana.

    PubMed Central

    Lim, K Y; Skalicka, K; Koukalova, B; Volkov, R A; Matyasek, R; Hemleben, V; Leitch, A R; Kovarik, A

    2004-01-01

    An approximately 135-bp sequence called the A1/A2 repeat was isolated from the transcribed region of the 26-18S rDNA intergenic spacer (IGS) of Nicotiana tomentosiformis. Fluorescence in situ hybridization (FISH) and Southern blot analysis revealed its occurrence as an independent satellite (termed an A1/A2 satellite) outside of rDNA loci in species of Nicotiana section Tomentosae. The chromosomal location, patterns of genomic dispersion, and copy numbers of its tandemly arranged units varied between the species. In more distantly related Nicotiana species the A1/A2 repeats were found only at the nucleolar organizer regions (NOR). There was a trend toward the elimination of the A1/A2 satellite in N. tabacum (tobacco), an allotetraploid with parents closely related to the diploids N. sylvestris and N. tomentosiformis. This process may have already commenced in an S(3) generation of synthetic tobacco. Cytosine residues in the IGS were significantly hypomethylated compared with the A1/A2 satellite. There was no clear separation between the IGS and satellite fractions in sequence analysis of individual clones and we found no evidence for CG suppression. Taken together the data indicate a dynamic nature of the A1/A2 repeats in Nicotiana genomes, with evidence for recurrent integration, copy number expansions, and contractions. PMID:15126410

  8. Cytokinin oxidase/dehydrogenase overexpression modifies antioxidant defense against heat, drought and their combination in Nicotiana tabacum plants.

    PubMed

    Lubovská, Zuzana; Dobrá, Jana; Storchová, Helena; Wilhelmová, Naďa; Vanková, Radomíra

    2014-11-01

    Cytokinins (CKs) as well as the antioxidant enzyme system (AES) play important roles in plant stress responses. The expression and activity of antioxidant enzymes (AE) were determined in drought, heat and combination of both stresses, comparing the response of tobacco plants overexpressing the main cytokinin degrading enzyme, cytokinin oxidase/dehydrogenase, under the control of root-specific WRKY6 promoter (W6:CKX1 plants) or constitutive promoter (35S:CKX1 plants) and the corresponding wild-type (WT). Expression levels as well as activities of cytosolic ascorbate peroxidase, catalase 3, and cytosolic superoxide dismutase were low under optimal conditions and increased after heat and combined stress in all genotypes. Unlike catalase 3, two other peroxisomal enzymes, catalase 1 and catalase 2, were transcribed extensively under control conditions. Heat stress, in contrast to drought or combined stress, increased catalase 1 and reduced catalase 2 expression in WT and W6:CKX1 plants. In 35S:CKX1, catalase 1 expression was enhanced by heat or drought, but not under combined stress conditions. Mitochondrial superoxide dismutase expression was generally higher in 35S:CKX1 plants than in WT. Genes encoding for chloroplastic AEs, stromatal ascorbate peroxidase, thylakoidal ascorbate peroxidase and chloroplastic superoxide dismutase, were strongly transcribed under control conditions. All stresses down-regulated their expression in WT and W6:CKX1, whereas more stress-tolerant 35S:CKX1 plants maintained high expression during drought and heat. The achieved data show that the effect of down-regulation of CK levels on AES may be mediated by altered habit, resulting in improved stress tolerance, which is associated with diminished stress impact on photosynthesis, and changes in source/sink relations.

  9. Molecular diversity, population structure, and linkage disequilibrium in a worldwide collection of tobacco (Nicotiana tabacum L.) germplasm

    PubMed Central

    2012-01-01

    Background The goals of our study were to assess the phylogeny and the population structure of tobacco accessions representing a wide range of genetic diversity; identify a subset of accessions as a core collection capturing most of the existing genetic diversity; and estimate, in the tobacco core collection, the extent of linkage disequilibrium (LD) in seven genomic regions using simple sequence repeat (SSR) markers. To this end, a collection of accessions were genotyped with SSR markers. Molecular diversity was evaluated and LD was analyzed across seven regions of the genome. Results A genotyping database for 312 tobacco accessions was profiled with 49 SSR markers. Principal Coordinate Analysis (PCoA) and Bayesian cluster analysis revealed structuring of the tobacco population with regard to commercial classes and six main clades were identified, which correspond to "Oriental", Flue-Cured", "Burley", "Dark", "Primitive", and "Other" classes. Pairwise kinship was calculated between accessions, and an overall low level of co-ancestry was observed. A set of 89 genotypes was identified that captured the whole genetic diversity detected at the 49 loci. LD was evaluated on these genotypes, using 422 SSR markers mapping on seven linkage groups. LD was estimated as squared correlation of allele frequencies (r2). The pattern of intrachromosomal LD revealed that in tobacco LD extended up to distances as great as 75 cM with r2 > 0.05 or up to 1 cM with r2 > 0.2. The pattern of LD was clearly dependent on the population structure. Conclusions A global population of tobacco is highly structured. Clustering highlights the accessions with the same market class. LD in tobacco extends up to 75 cM and is strongly dependent on the population structure. PMID:22435796

  10. Cloning, Transformation and Expression of Human Interferon α2b Gene in Tobacco Plant (Nicotiana tabacum cv. xanthi)

    PubMed Central

    Ahangarzadeh, Shahrzad; Daneshvar, Mohammad Hosein; Rajabi-Memari, Hamid; Galehdari, Hamid; Alamisaied, Khalil

    2012-01-01

    Background Molecular farming is the production of important recombinant proteins in transgenic organisms on an agricultural scale. Interferons are proteins with antiviral and antitumor activities and can be used for viral infections and cancers treatments. Objectives This study reports the transformation of INF α2b gene in tobacco plant for the first time in Iran. Materials and Methods Interferon α2b gene was amplified by PCR using specific primers containing appropriate restriction enzymes, plant highly expression sequence and Histidine tag sequence. Target sequence was cloned in plant expression vector pCAMBIA1304 and the construct named pCAMINFα. pCAMINFα was transferred to E. coli strain DH5α and plated on LB agar medium containing kanamycin 50 mgl-1. The colonies were confirmed by colony PCR and sequencing. The construct was transferred into Agrobacterium tumefaciens by freeze-thaw method and transformed colonies were confirmed by colony PCR. Tobacco plants (cultivar xanthi) were inoculated with A. tumefaciens strain LBA4404 by leaf disc method. Inoculated explants were cultured on MSII (MS + BAP 1mgl-1 + NAA 0.1 mgl-1) at 28°C and darkness for 48 hours. Then explants were transferred to selection medium containing cephotaxime (250 mgl-1) and hygromycin (15 mgl-1) in a 16/8 (day/night) h photoperiod in growth room with an irradiance of 5000 lux. Transgenic plants were regenerated and transferred to perlite. Genomic DNA was extracted from regenerated plants by Dellaporta method at 5-leaf step and transgenic lines were confirmed by PCR with specific primers. Expression of Interferon α2b gene was confirmed by dot blotting. Conclusions Since no report of interferon alpha production in plants in Iran has been expressed yet, this research could create a field of producing this drug in tobacco, in Iran. PMID:24624166

  11. Modulation of miR156 to identify traits associated with vegetative phase change in tobacco (Nicotiana tabacum).

    PubMed

    Feng, Shengjun; Xu, Yunmin; Guo, Changkui; Zheng, Jirong; Zhou, Bingying; Zhang, Yuting; Ding, Yue; Zhang, Lu; Zhu, Zhujun; Wang, Huasen; Wu, Gang

    2016-03-01

    After germination, plants progress through juvenile and adult phases of vegetative development before entering the reproductive phase. The character and timing of these phases vary significantly between different plant species, which makes it difficult to know whether temporal variations in various vegetative traits represent the same, or different, developmental processes. miR156 has been shown to be the master regulator of vegetative development in plants. Overexpression of miR156 prolongs the juvenile phase of development, whereas knocking-down the level of miR156 promotes the adult phase of development. Therefore, artificial modulation of miR156 expression is expected to cause corresponding changes in vegetative-specific traits in different plant species, particularly in those showing no substantial difference in morphology during vegetative development. To identify specific traits associated with the juvenile-to-adult transition in tobacco, we examined the phenotype of transgenic tobacco plants with elevated or reduced levels of miR156. We found that leaf shape, the density of abaxial trichomes, the number of leaf veins, the number of stomata, the size and density of epidermal cells, patterns of epidermal cell staining, the content of chlorophyll and the rate of photosynthesis, are all affected by miR156. These newly identified miR156-regulated traits therefore can be used to distinguish between juvenile and adult phases of development in tobacco, and provide a starting point for future studies of vegetative phase change in the family Solanaceae.

  12. Arabidopsis LOS5/ABA3 overexpression in transgenic tobacco (Nicotiana tabacum cv. Xanthi-nc) results in enhanced drought tolerance.

    PubMed

    Yue, Yuesen; Zhang, Mingcai; Zhang, Jiachang; Duan, Liusheng; Li, Zhaohu

    2011-10-01

    Drought is a major environmental stress factor that affects growth and development of plants. Abscisic acid (ABA), osmotically active compounds, and synthesis of specific proteins, such as proteins that scavenge oxygen radicals, are crucial for plants to adapt to water deficit. LOS5/ABA3 (LOS5) encodes molybdenum-cofactor sulfurase, which is a key regulator of ABA biosynthesis. We overexpressed LOS5 in tobacco using Agrobacterium-mediated transformation. Detached leaves of LOS5-overexpressing seedlings showed lower transpirational water loss than that of nontransgenic seedlings in the same period under normal conditions. When subjected to water-deficit stress, transgenic plants showed less wilting, maintained higher water content and better cellular membrane integrity, accumulated higher quantities of ABA and proline, and exhibited higher activities of antioxidant enzymes, i.e., superoxide dismutase, catalase, peroxidase and ascorbate peroxidase, as compared with control plants. Furthermore, LOS5-overexpressing plants treated with 30% polyethylene glycol showed similar performance in cellular membrane protection, ABA and proline accumulation, and activities of catalase and peroxidase to those under drought stress. Thus, overexpression of LOS5 in transgenic tobacco can enhance drought tolerance.

  13. Comparative transcriptome analysis of tobacco (Nicotiana tabacum) leaves to identify aroma compound-related genes expressed in different cultivated regions.

    PubMed

    Lei, Bo; Zhao, Xue-Hua; Zhang, Kai; Zhang, Jie; Ren, Wei; Ren, Zhu; Chen, Yi; Zhao, Hui-Na; Pan, Wen-Jie; Chen, Wei; Li, Hong-Xun; Deng, Wen-Ya; Ding, Fu-Zhang; Lu, Kun

    2013-01-01

    To identify genes that are differentially expressed in tobacco in response to environmental changes and to decipher the mechanisms by which aromatic carotenoids are formed in tobacco, an Agilent Tobacco Gene Expression microarray was adapted for transcriptome comparison of tobacco leaves derived from three cultivated regions of China, Kaiyang (KY), Weining (WN) and Tianzhu (TZ). A total of 1,005 genes were differentially expressed between leaves derived from KY and TZ, 733 between KY and WN, and 517 between TZ and WN. Genes that were upregulated in leaves from WN and TZ tended to be involved in secondary metabolism pathways, and included several carotenoid pathway genes, e.g., NtPYS, NtPDS, and NtLCYE, whereas those that were down-regulated tended to be involved in the response to temperature and light. The expression of 10 differentially expressed genes (DEGs) was evaluated by real-time quantitative polymerase chain reaction (qRT-PCR) and found to be consistent with the microarray data. Gene Ontology and MapMan analyses indicate that the genes that were differentially expressed among the three cultivated regions were associated with the light reaction of photosystem II, response to stimuli, and secondary metabolism. High-performance liquid chromatography (HPLC) analysis showed that leaves derived from KY had the lowest levels of lutein, β-carotene, and neoxanthin, whereas the total carotenoid content in leaves from TZ was greatest, a finding that could well be explained by the expression patterns of DEGs in the carotenoid pathway. These results may help elucidate the molecular mechanisms underlying environmental adaptation and accumulation of aroma compounds in tobacco.

  14. Effect of lead (Pb) on the systemic movement of RNA viruses in tobacco (Nicotiana tabacum var. Turkish).

    PubMed

    Alkhatib, Rami; Creamer, Rebecca; Lartey, Robert T; Ghoshroy, Soumitra

    2011-08-01

    Effect of various lead (Pb) concentrations on the systemic movement of RNA viruses was examined in tobacco plants. Prior to inoculation, plants were grown hydroponically for 6 days in Hoagland's solution supplemented with five concentrations of lead nitrate [Pb(NO(3))(2)]: 0.0 (control), 10, 15, 50, and 100 μM. Four different RNA viruses with different cell-to-cell movement mechanisms were used. Two weeks after inoculation lower and upper leaves of each treatment were harvested and examined for the presence of viral coat protein. In plants inoculated with Tobacco mosaic virus, Potato virus X, and Tobacco etch virus, TEM images and western blot assays confirmed the presence of viral coat proteins in the upper leaves of all lead treatments. However, in plants inoculated with Turnip vein-clearing virus (TVCV), no signs of viral particles were detected in the upper leaves of plants treated with 10 μM or 15 μM lead nitrate. In contrast, plants treated with high concentrations of lead nitrate (50 μM or 100 μM) showed viral particles in their upper leaves. In plants treated with 10 μM or 15 μM lead nitrate, callose accumulation was the same as in control plants. This suggests that non-toxic concentrations of lead nitrate may trigger the production of putative cellular factors in addition to callose that interfere with the TVCV systemic movement. In contrast, plants treated with 100 μM lead nitrate showed less callose as compared to control plants, facilitating the systemic movement of TVCV.

  15. Spatial patterns of senescence and development-dependent distribution of reactive oxygen species in tobacco (Nicotiana tabacum) leaves.

    PubMed

    Niewiadomska, Ewa; Polzien, Lisa; Desel, Christine; Rozpadek, Piotr; Miszalski, Zbigniew; Krupinska, Karin

    2009-07-01

    Senescence of tobacco leaves is distributed non-uniformly over a leaf blade. While photosynthetic competence and expression of photosynthesis-associated genes decline in interveinal areas of the leaf lamina with advancing age of the leaf, they are maintained at high levels in the tissue surrounding the veins. In contrast, expression of senescence-associated genes (SAG) was enhanced in both areas of the leaf blade. Accumulation of hydrogen peroxide was shown to precede the phase of senescence initiation in the veinal tissue. In the interveinal tissue, the level of hydrogen peroxide was increased with senescence progression and paralleled by an increase in the level of superoxide anions. It is hypothesized that the spatial differences in superoxide anions are important for the non-uniform down-regulation of photosynthesis-associated genes (PAG), while hydrogen peroxide is responsible for up-regulation of SAG.

  16. Isolation and Compositional Analysis of a CP12-Associated Complex of Calvin Cycle Enzymes from Nicotiana tabacum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    CP12 is a small intrinsically unstructured protein that forms a multiprotein complex with two Calvin Cycle enzymes, phosphoribulokinase (PRK) and NAD(P)-dependent glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The complex can be reconstituted in vitro from recombinant proteins under conditions t...

  17. Cloning and characterization of TaVIP2 gene from Triticum aestivum and functional analysis in Nicotiana tabacum

    PubMed Central

    Zhao, Pei; Wang, Ke; Lin, Zhishan; Zhang, Wei; Du, Lipu; Zhang, Yunlong; Ye, Xingguo

    2016-01-01

    Wheat is recalcitrant to genetic transformation. A potential solution is to manipulate the expression of some host proteins involved in T-DNA integration process. VirE2 interacting protein 2 (VIP2) plays an important role in T-DNA transport and integration. In this study, a TaVIP2 gene was cloned from common wheat. Southern blot and allele-specific polymerase chain reaction (AS-PCR) combined with an online chromosomal location software tool revealed that three TaVIP2 genes were located on wheat chromosomes 1AL, 1BL, and 1DL. These three homoeoallelic TaVIP2 genes all contained 13 exons and 12 introns, and their coding sequences were the same; there were a few single nucleotide polymorphisms (SNPs) among the three genes. The heterologous expression of the TaVIP2 gene in tobacco led to enhancement of the Agrobacterium-mediated transformation efficiency up to 2.5-fold. Transgenic tobacco plants expressing TaVIP2 showed enhanced resistance to powdery mildew. Further quantitative real-time PCR (qRT-PCR) revealed that overexpression of TaVIP2 in transgenic tobacco up-regulated the expression of an endogenous gene, NtPR-1, which likely contributed to powdery mildew resistance in transgenic tobacco. Our study indicates that the TaVIP2 gene may be highly useful in efforts to improve Agrobacterium-mediated transformation efficiency and to enhance powdery mildew resistance in wheat. PMID:27857194

  18. Effects of Lead (Pb) on the Systemic Movement of RNA Viruses in Tobacco (Nicotiana tabacum var. Turkish)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Effect of different lead (Pb) concentrations on the systemic movement of RNA viruses was examined in tobacco plants. Prior to inoculation, plants were grown hydroponically for six days in Hoagland's solution supplemented with five concentrations of lead nitrate [Pb(NO3)2]:0.0 (control), 10 uM, 15 u...

  19. Effect of calcium carbonate on cadmium and nutrients uptake in tobacco (Nicotiana tabacum L.) planted on contaminated soil.

    PubMed

    Zeng, Wei-Ai; Li, Fan; Zhou, Hang; Qin, Xiao-Li; Zou, Zi-Jin; Tian, Tao; Zeng, Min; Liao, Bo-Han

    2016-01-01

    In the present study, calcium carbonate (CaCO3) was applied to Cd-contaminated soil at rates of 0, 0.5 and 1.0 g kg(-1). The effect of CaCO3 on soil pH, organic matter, available Cd, exchangeable Cd and level of major nutrients in a tobacco field and on accumulation of various elements in tobacco plants was determined. The results showed that CaCO3 application significantly increased the pH level, available P and exchangeable Ca but decreased organic matter, available Cd, exchangeable Cd, available heavy metals (Fe, Mn, Zn and Cu) and available K in soil. Additionally, CaCO3 application substantially reduced Cd accumulation in tobacco roots, stems, upper leaves, middle leaves and lower leaves, with maximum decrease of 22.3%, 32.1%, 24.5%, 22.0% and 18.2%, respectively. There were large increase in total Ca and slight increases in total N and K but decrease to varying degrees in total Fe, Cu and Zn due to CaCO3 application. CaCO3 had little effect on total P and Mn levels in tobacco leaves.

  20. The role of gluconate production by Pseudomonas spp. in the mineralization and bioavailability of calcium-phytate to Nicotiana tabacum.

    PubMed

    Giles, Courtney D; Hsu, Pei-Chun Lisa; Richardson, Alan E; Hurst, Mark R H; Hill, Jane E

    2015-12-01

    Organic phosphorus (P) is abundant in most soils but is largely unavailable to plants. Pseudomonas spp. can improve the availability of P to plants through the production of phytases and organic anions. Gluconate is a major component of Pseudomonas organic anion production and may therefore play an important role in the mineralization of insoluble organic P forms such as calcium-phytate (CaIHP). Organic anion and phytase production was characterized in 2 Pseudomonas spp. soil isolates (CCAR59, Ha200) and an isogenic mutant of strain Ha200, which lacked a functional glucose dehydrogenase (Gcd) gene (strain Ha200 gcd::Tn5B8). Wild-type and mutant strains of Pseudomonas spp. were evaluated for their ability to solubilize and hydrolyze CaIHP and to promote the growth and assimilation of P by tobacco plants. Gluconate, 2-keto-gluconate, pyruvate, ascorbate, acetate, and formate were detected in Pseudomonas spp. supernatants. Wild-type pseudomonads containing a functional gcd could produce gluconate and mineralize CaIHP, whereas the isogenic mutant could not. Inoculation with Pseudomonas improved the bioavailability of CaIHP to tobacco plants, but there was no difference in plant growth response due to Gcd function. Gcd function is required for the mineralization of CaIHP in vitro; however, further studies will be needed to quantify the relative contribution of specific organic anions such as gluconate to plant growth promotion by soil pseudomonads.

  1. Role of transpiration and metabolism in translocation and accumulation of cadmium in tobacco plants (Nicotiana tabacum L.).

    PubMed

    Liu, Haiwei; Wang, Haiyun; Ma, Yibing; Wang, Haohao; Shi, Yi

    2016-02-01

    Tobacco plants grown in pots and in hydroponic culture accumulated cadmium (Cd) particularly: the Cd content of tobacco leaves exceeded 100 mg/kg and the enrichment factor (the ratio of Cd in leaves to that in soil) was more than 4. These high levels of accumulation identify tobacco as a hyperaccumulator of Cd. Two transpiration inhibitors (paraffin or CaCl2) and shade decreased the Cd content of tobacco leaves, and the decrease showed a linear relationship with the leaf transpiration rate. A metabolism inhibitor, namely 2,4-dinitrophenol (DNP), and low temperature (4 °C) also lowered the Cd content of tobacco leaves, but the inhibitory effect of low temperature was greater. In the half number of leaves that were shaded, the Cd content decreased to 26.5% of that in leaves that were not shaded in the same tobacco plants. These results suggests that translocation of Cd from the medium to the leaves is driven by the symplastic and the apoplastic pathways. Probably, of the two crucial steps in the translocation of Cd in tobacco plants, one, namely uptake from the medium to the xylem, is energy-dependent whereas the other, namely the transfer from the xylem to the leaves, is driven mainly by transpiration.

  2. RNA sequencing analysis reveals transcriptomic variations in tobacco (Nicotiana tabacum) leaves affected by climate, soil, and tillage factors.

    PubMed

    Lei, Bo; Lu, Kun; Ding, Fuzhang; Zhang, Kai; Chen, Yi; Zhao, Huina; Zhang, Lin; Ren, Zhu; Qu, Cunmin; Guo, Wenjing; Wang, Jing; Pan, Wenjie

    2014-04-11

    The growth and development of plants are sensitive to their surroundings. Although numerous studies have analyzed plant transcriptomic variation, few have quantified the effect of combinations of factors or identified factor-specific effects. In this study, we performed RNA sequencing (RNA-seq) analysis on tobacco leaves derived from 10 treatment combinations of three groups of ecological factors, i.e., climate factors (CFs), soil factors (SFs), and tillage factors (TFs). We detected 4980, 2916, and 1605 differentially expressed genes (DEGs) that were affected by CFs, SFs, and TFs, which included 2703, 768, and 507 specific and 703 common DEGs (simultaneously regulated by CFs, SFs, and TFs), respectively. GO and KEGG enrichment analyses showed that genes involved in abiotic stress responses and secondary metabolic pathways were overrepresented in the common and CF-specific DEGs. In addition, we noted enrichment in CF-specific DEGs related to the circadian rhythm, SF-specific DEGs involved in mineral nutrient absorption and transport, and SF- and TF-specific DEGs associated with photosynthesis. Based on these results, we propose a model that explains how plants adapt to various ecological factors at the transcriptomic level. Additionally, the identified DEGs lay the foundation for future investigations of stress resistance, circadian rhythm and photosynthesis in tobacco.

  3. A survey of resistance to Tomato bushy stunt virus in the genus Nicotiana reveals that the hypersensitive response is triggered by one of three different viral proteins.

    PubMed

    Angel, Carlos A; Schoelz, James E

    2013-02-01

    In this study, we screened 22 Nicotiana spp. for resistance to the tombusviruses Tomato bushy stunt virus (TBSV), Cucumber necrosis virus, and Cymbidium ringspot virus. Eighteen species were resistant, and resistance was manifested in at least two different categories. In all, 13 species responded with a hypersensitive response (HR)-type resistance, whereas another five were resistant but either had no visible response or responded with chlorotic lesions rather than necrotic lesions. Three different TBSV proteins were found to trigger HR in Nicotiana spp. in an agroinfiltration assay. The most common avirulence (avr) determinant was the TBSV coat protein P41, a protein that had not been previously recognized as an avr determinant. A mutational analysis confirmed that the coat protein rather than the viral RNA sequence was responsible for triggering HR, and it triggered HR in six species in the Alatae section. The TBSV P22 movement protein triggered HR in two species in section Undulatae (Nicotiana glutinosa and N. edwardsonii) and one species in section Alatae (N. forgetiana). The TBSV P19 RNA silencing suppressor protein triggered HR in sections Sylvestres (N. sylvestris), Nicotiana (N. tabacum), and Alatae (N. bonariensis). In general, Nicotiana spp. were capable of recognizing only one tombusvirus avirulence determinant, with the exceptions of N. bonariensis and N. forgetiana, which were each able to recognize P41, as well as P19 and P22, respectively. Agroinfiltration failed to detect the TBSV avr determinants responsible for triggering HR in N. arentsii, N. undulata, and N. rustica. This study illustrates the breadth and variety of resistance responses to tombusviruses that exists in the Nicotiana genus.

  4. An interspecific Nicotiana hybrid as a useful and cost-effective platform for production of animal vaccines.

    PubMed

    Ling, Huai-Yian; Edwards, Aaron M; Gantier, Michael P; Deboer, Kathleen D; Neale, Alan D; Hamill, John D; Walmsley, Amanda M

    2012-01-01

    The use of transgenic plants to produce novel products has great biotechnological potential as the relatively inexpensive inputs of light, water, and nutrients are utilised in return for potentially valuable bioactive metabolites, diagnostic proteins and vaccines. Extensive research is ongoing in this area internationally with the aim of producing plant-made vaccines of importance for both animals and humans. Vaccine purification is generally regarded as being integral to the preparation of safe and effective vaccines for use in humans. However, the use of crude plant extracts for animal immunisation may enable plant-made vaccines to become a cost-effective and efficacious approach to safely immunise large numbers of farm animals against diseases such as avian influenza. Since the technology associated with genetic transformation and large-scale propagation is very well established in Nicotiana, the genus has attributes well-suited for the production of plant-made vaccines. However the presence of potentially toxic alkaloids in Nicotiana extracts impedes their use as crude vaccine preparations. In the current study we describe a Nicotiana tabacum and N. glauca hybrid that expresses the HA glycoprotein of influenza A in its leaves but does not synthesize alkaloids. We demonstrate that injection with crude leaf extracts from these interspecific hybrid plants is a safe and effective approach for immunising mice. Moreover, this antigen-producing alkaloid-free, transgenic interspecific hybrid is vigorous, with a high capacity for vegetative shoot regeneration after harvesting. These plants are easily propagated by vegetative cuttings and have the added benefit of not producing viable pollen, thus reducing potential problems associated with bio-containment. Hence, these Nicotiana hybrids provide an advantageous production platform for partially purified, plant-made vaccines which may be particularly well suited for use in veterinary immunization programs.

  5. Non-host Plant Resistance against Phytophthora capsici Is Mediated in Part by Members of the I2 R Gene Family in Nicotiana spp.

    PubMed

    Vega-Arreguín, Julio C; Shimada-Beltrán, Harumi; Sevillano-Serrano, Jacobo; Moffett, Peter

    2017-01-01

    The identification of host genes associated with resistance to Phytophthora capsici is crucial to developing strategies of control against this oomycete pathogen. Since there are few sources of resistance to P. capsici in crop plants, non-host plants represent a promising source of resistance genes as well as excellent models to study P. capsici - plant interactions. We have previously shown that non-host resistance to P. capsici in Nicotiana spp. is mediated by the recognition of a specific P. capsici effector protein, PcAvr3a1 in a manner that suggests the involvement of a cognate disease resistance (R) genes. Here, we have used virus-induced gene silencing (VIGS) and transgenic tobacco plants expressing dsRNA in Nicotiana spp. to identify candidate R genes that mediate non-host resistance to P. capsici. Silencing of members of the I2 multigene family in the partially resistant plant N. edwardsonii and in the resistant N. tabacum resulted in compromised resistance to P. capsici. VIGS of two other components required for R gene-mediated resistance, EDS1 and SGT1, also enhanced susceptibility to P. capsici in N. edwardsonii, as well as in the susceptible plants N. benthamiana and N. clevelandii. The silencing of I2 family members in N. tabacum also compromised the recognition of PcAvr3a1. These results indicate that in this case, non-host resistance is mediated by the same components normally associated with race-specific resistance.

  6. Non-host Plant Resistance against Phytophthora capsici Is Mediated in Part by Members of the I2 R Gene Family in Nicotiana spp.

    PubMed Central

    Vega-Arreguín, Julio C.; Shimada-Beltrán, Harumi; Sevillano-Serrano, Jacobo; Moffett, Peter

    2017-01-01

    The identification of host genes associated with resistance to Phytophthora capsici is crucial to developing strategies of control against this oomycete pathogen. Since there are few sources of resistance to P. capsici in crop plants, non-host plants represent a promising source of resistance genes as well as excellent models to study P. capsici – plant interactions. We have previously shown that non-host resistance to P. capsici in Nicotiana spp. is mediated by the recognition of a specific P. capsici effector protein, PcAvr3a1 in a manner that suggests the involvement of a cognate disease resistance (R) genes. Here, we have used virus-induced gene silencing (VIGS) and transgenic tobacco plants expressing dsRNA in Nicotiana spp. to identify candidate R genes that mediate non-host resistance to P. capsici. Silencing of members of the I2 multigene family in the partially resistant plant N. edwardsonii and in the resistant N. tabacum resulted in compromised resistance to P. capsici. VIGS of two other components required for R gene-mediated resistance, EDS1 and SGT1, also enhanced susceptibility to P. capsici in N. edwardsonii, as well as in the susceptible plants N. benthamiana and N. clevelandii. The silencing of I2 family members in N. tabacum also compromised the recognition of PcAvr3a1. These results indicate that in this case, non-host resistance is mediated by the same components normally associated with race-specific resistance. PMID:28261255

  7. Defence Reporter. Winter 2012

    DTIC Science & Technology

    2012-01-01

    Reporter is one part of a series of services and products produced by ATHENA to keep readers up -to- date with the latest developments in key areas...have been added to the MOD’s ATHENA Collection. Defence Reporter is available by subscription. To sign up for this free service, please send an e...study identified a number of critical REEs in addition to several non-REE materials. A ‘bottom- up ’ study assessed market data and information on

  8. Defence Reporter. Autumn 2013

    DTIC Science & Technology

    2013-01-01

    Reporter is one part of a series of services and products produced by ATHENA to keep readers up -to- date with the latest developments in key areas...ATHENA Collection. Defence Reporter is available by subscription. To sign up for this free service, please send an e-mail with your full name and...here is that in a joined- up coalition environment our allies will not be able to discover UK data and if they do have it, they may not treat it

  9. High-Level Transient Expression of ER-Targeted Human Interleukin 6 in Nicotiana benthamiana

    PubMed Central

    Nausch, Henrik; Mikschofsky, Heike; Koslowski, Roswitha; Meyer, Udo; Broer, Inge; Huckauf, Jana

    2012-01-01

    Tobacco plants can be used to express recombinant proteins that cannot be produced in a soluble and active form using traditional platforms such as Escherichia coli. We therefore expressed the human glycoprotein interleukin 6 (IL6) in two commercial tobacco cultivars (Nicotiana tabacum cv. Virginia and cv. Geudertheimer) as well as the model host N. benthamiana to compare different transformation strategies (stable vs. transient expression) and subcellular targeting (apoplast, endoplasmic reticulum (ER) and vacuole). In T0 transgenic plants, the highest expression levels were achieved by ER targeting but the overall yields of IL6 were still low in the leaves (0.005% TSP in the ER, 0.0008% in the vacuole and 0.0005% in the apoplast). The apoplast variant accumulated to similar levels in leaves and seeds, whereas the ER-targeted variant was 1.2-fold more abundant in seeds and the vacuolar variant was 6-fold more abundant in seeds. The yields improved in subsequent generations, with the best-performing T2 plants producing the ER-targeted IL6 at 0.14% TSP in both leaves and seeds. Transient expression of ER-targeted IL6 in leaves using the MagnICON system resulted in yields of up to 7% TSP in N. benthamiana, but only 1% in N. tabacum cv. Virginia and 0.5% in cv. Geudertheimer. Although the commercial tobacco cultivars produced up to threefold more biomass than N. benthamiana, this was not enough to compensate for the lower overall yields. The recombinant IL6 produced by transient and stable expression in plants was biologically active and presented as two alternative bands matching the corresponding native protein. PMID:23152824

  10. Quantitative Analysis of the Fate of Exogenous DNA in Nicotiana Protoplasts 1

    PubMed Central

    Uchimiya, Hirofumi; Murashige, Toshio

    1977-01-01

    After a 5-hour incubation of protoplasts of Nicotiana tabacum L. `Xanthi' with 3H-DNA (7.26 μg/ml) from N. tabacum L. `Xanthi nc' 3.5% of the initial radioactivity was found in acid-insoluble substances of the protoplasts. The addition of DEAE-dextran and poly-l-lysine to the incubation medium nearly doubled radioactivity adsorption. The absorption was inhibited by 2,4-dinitrophenol, KCN, and low temperature (0 C); this inhibition could not be reversed by exogenous ATP. About 500 tobacco plants established from protoplasts of a normally tobacco-mosaic virus-susceptible cultivar that had been allowed to absorb DNA prepared from a resistant cultivar did not show transfer of the virus-resistant gene. A detailed analysis was performed of the disposition of exogenous DNA in plant protoplasts, by employing Escherichia coli3H-DNA and Nicotiana glutinosa protoplasts. In 5 to 20 hours, about 10% of the 3H-DNA entered the protoplasts. Competition experiments between the 3H-DNA and unlabeled DNA or thymidine showed that the entry occurred as undegraded 3H-DNA. Examination of intraprotoplast fractions revealed that 60 to 80% of the absorbed radioactivity resided in the “soluble” fraction of the cytoplasm and 20% in the nuclear fraction. The mitochondrion fraction also contained measurable radioactivity. Sizing on sucrose density gradients showed that the bulk of the absorbed E. coli DNA had been depolymerized. Of the incorporated radioactivity, 15% was accountable as DNA, exogenous as well as resynthesized, and 15% as RNA, protein, and other cell constituents. DNA/DNA hybridization test indicated that 17.6% of the re-extractable 3H-DNA retained homology with the E. coli DNA; this was equivalent to 2.6% of the absorbed radioactivity. Resynthesized receptor protoplast DNA was represented by a fraction at least 1.7% of the total absorbed radioactivity. The amount of bacterial DNA remaining in protoplasts suggests that each protoplast retained 2.3 × 10−15g donor DNA, or

  11. Strong host resistance targeted against a viral suppressor of the plant gene silencing defence mechanism.

    PubMed Central

    Li, H W; Lucy, A P; Guo, H S; Li, W X; Ji, L H; Wong, S M; Ding, S W

    1999-01-01

    The 2b protein encoded by cucumber mosaic cucumovirus (Cmv2b) acts as an important virulence determinant by suppressing post-transcriptional gene silencing (PTGS), a natural plant defence mechanism against viruses. We report here that the tomato aspermy cucumovirus 2b protein (Tav2b), when expressed from the unrelated tobacco mosaic tobamovirus (TMV) RNA genome, activates strong host resistance responses to TMV in tobacco which are typical of the gene-for-gene disease resistance mechanism. Domain swapping between Cmv2b, which does not elicit these responses, and Tav2b, revealed functional domains in Tav2b critical for triggering virus resistance and hypersensitive cell death. Furthermore, substitution of two amino acids from Tav2b by those found at the same positions in Cmv2b, Lys21-->Val and Arg28-->Ser, abolished the ability to induce hypersensitive cell death and virus resistance. However, in Nicotiana benthamiana, a species related to tobacco, Tav2b functions as a virulence determinant and suppresses PTGS. Thus, a viral suppressor of the host gene silencing defence mechanism is the target of another independent host resistance mechanism. Our results provide new insights into the complex molecular strategies employed by viruses and their hosts for defence, counter-defence and counter counter-defence. PMID:10329615

  12. Solar Ultraviolet-B Radiation and Insect Herbivory Trigger Partially Overlapping Phenolic Responses in Nicotiana attenuata and Nicotiana longiflora

    PubMed Central

    Izaguirre, Miriam M.; Mazza, Carlos A.; SvatoŠ, AleŠ; Baldwin, Ian T.; BallarÉ, Carlos L.

    2007-01-01

    Background and Aims Plants exposed to solar ultraviolet-B radiation (UV-B, 280–315 nm) frequently suffer less insect herbivory than do plants that receive attenuated levels of UV-B. This anti-herbivore effect of solar UV-B exposure, which has been documented in several ecosystems, is in part mediated by changes in plant tissue quality. Exposure to UV-B can modify the abundance of a number of secondary metabolites, including phenolic compounds with potential impacts on insect herbivores. The aim of this study is to assess the potential anti-herbivore role of UV-B-induced phenolic compounds by comparing the phenolic profiles induced by UV-B and simulated insect herbivory in two wild species of the genus Nicotiana. Methods Plants grown under field and glasshouse conditions were exposed to contrasting levels of UV-B. Half of the plants of the attenuated UV-B treatment were given a simulated herbivory treatment, where leaves were mechanically damaged and immediately treated with oral secretions of Manduca sexta caterpillars. This treatment is known to mimic the impact of real herbivory on the expression of plant defences in Nicotiana. Phenolic profiles induced by UV-B and simulated herbivory were characterized using high-performance liquid chromatography–mass spectrometry (HPLC–MS). Key Results UV-B induced the accumulation of several UV-absorbing phenolic compounds that are known to play a significant role in UV-B screening. Interestingly, there was a significant convergence in the phenolic profiles induced by UV-B and simulated herbivory: chlorogenic acid and dicaffeoylspermidine isomers, in particular, displayed a similar pattern of response to these stimuli. In contrast, rutin, the only flavonoid that accumulated in significant quantities in the experiments, was only induced by UV-B. Conclusions The results suggest that the anti-herbivory effect induced by UV-B may be mediated at least in part by the accumulation of phenylpropanoid derivatives that are

  13. Plant Oxidosqualene Metabolism: Cycloartenol Synthase–Dependent Sterol Biosynthesis in Nicotiana benthamiana

    PubMed Central

    Gas-Pascual, Elisabet; Berna, Anne; Bach, Thomas J.; Schaller, Hubert

    2014-01-01

    The plant sterol pathway exhibits a major biosynthetic difference as compared with that of metazoans. The committed sterol precursor is the pentacyclic cycloartenol (9β,19-cyclolanost-24-en-3β-ol) and not lanosterol (lanosta-8,24-dien-3β-ol), as it was shown in the late sixties. However, plant genome mining over the last years revealed the general presence of lanosterol synthases encoding sequences (LAS1) in the oxidosqualene cyclase repertoire, in addition to cycloartenol synthases (CAS1) and to non-steroidal triterpene synthases that contribute to the metabolic diversity of C30H50O compounds on earth. Furthermore, plant LAS1 proteins have been unambiguously identified by peptidic signatures and by their capacity to complement the yeast lanosterol synthase deficiency. A dual pathway for the synthesis of sterols through lanosterol and cycloartenol was reported in the model Arabidopsis thaliana, though the contribution of a lanosterol pathway to the production of 24-alkyl-Δ5-sterols was quite marginal (Ohyama et al. (2009) PNAS 106, 725). To investigate further the physiological relevance of CAS1 and LAS1 genes in plants, we have silenced their expression in Nicotiana benthamiana. We used virus induced gene silencing (VIGS) based on gene specific sequences from a Nicotiana tabacum CAS1 or derived from the solgenomics initiative (http://solgenomics.net/) to challenge the respective roles of CAS1 and LAS1. In this report, we show a CAS1-specific functional sterol pathway in engineered yeast, and a strict dependence on CAS1 of tobacco sterol biosynthesis. PMID:25343375

  14. Plant oxidosqualene metabolism: cycloartenol synthase-dependent sterol biosynthesis in Nicotiana benthamiana.

    PubMed

    Gas-Pascual, Elisabet; Berna, Anne; Bach, Thomas J; Schaller, Hubert

    2014-01-01

    The plant sterol pathway exhibits a major biosynthetic difference as compared with that of metazoans. The committed sterol precursor is the pentacyclic cycloartenol (9β,19-cyclolanost-24-en-3β-ol) and not lanosterol (lanosta-8,24-dien-3β-ol), as it was shown in the late sixties. However, plant genome mining over the last years revealed the general presence of lanosterol synthases encoding sequences (LAS1) in the oxidosqualene cyclase repertoire, in addition to cycloartenol synthases (CAS1) and to non-steroidal triterpene synthases that contribute to the metabolic diversity of C30H50O compounds on earth. Furthermore, plant LAS1 proteins have been unambiguously identified by peptidic signatures and by their capacity to complement the yeast lanosterol synthase deficiency. A dual pathway for the synthesis of sterols through lanosterol and cycloartenol was reported in the model Arabidopsis thaliana, though the contribution of a lanosterol pathway to the production of 24-alkyl-Δ(5)-sterols was quite marginal (Ohyama et al. (2009) PNAS 106, 725). To investigate further the physiological relevance of CAS1 and LAS1 genes in plants, we have silenced their expression in Nicotiana benthamiana. We used virus induced gene silencing (VIGS) based on gene specific sequences from a Nicotiana tabacum CAS1 or derived from the solgenomics initiative (http://solgenomics.net/) to challenge the respective roles of CAS1 and LAS1. In this report, we show a CAS1-specific functional sterol pathway in engineered yeast, and a strict dependence on CAS1 of tobacco sterol biosynthesis.

  15. A glycoside of Nicotina tabacum affects mouse dopaminergic behavior.

    PubMed

    Masuda, Y; Ohnuma, S; Kawagoe, M; Sugiyama, T

    2003-01-01

    Climbing in the forced swimming test is considered a dopaminergic-specific behavior. A substance of Nicotina tabacum affecting dopamine neuronal activity was investigated using the mouse behavioral system. The substance was found to be a glycoside with the peripheral sugar chain structures Fuc alpha 1-2Gal, Gal beta 1-4GlcNAc and GalNAc alpha 1-3GalNAc and with basic polymannoses. The glycoside dose-dependently increased behavior via D2 neuronal activity, but not D1 activity. This suggests that smoking can affect human brain function not only via the nicotinic cholinergic neuron, but also via the D2 neuron.

  16. Mechanisms of nitric-oxide-induced increase of free cytosolic Ca2+ concentration in Nicotiana plumbaginifolia cells.

    PubMed

    Lamotte, Olivier; Courtois, Cécile; Dobrowolska, Grazyna; Besson, Angélique; Pugin, Alain; Wendehenne, David

    2006-04-15

    In this study, we investigated a role for nitric oxide (NO) in mediating the elevation of the free cytosolic Ca(2+) concentration ([Ca(2+)](cyt)) in plants using Nicotiana plumbaginifolia cells expressing the Ca(2+) reporter apoaequorin. Hyperosmotic stress induced a fast increase of [Ca(2+)](cyt) which was strongly reduced by pretreating cell suspensions with the NO scavenger carboxy PTIO, indicating that NO mediates [Ca(2+)](cyt) changes in plant cells challenged by abiotic stress. Accordingly, treatment of transgenic N. plumbaginifolia cells with the NO donor diethylamine NONOate was followed by a transient increase of [Ca(2+)](cyt) sensitive to plasma membrane Ca(2+) channel inhibitors and antagonist of cyclic ADP ribose. We provided evidence that NO might activate plasma membrane Ca(2+) channels by inducing a rapid and transient plasma membrane depolarization. Furthermore, NO-induced elevation of [Ca(2+)](cyt) was suppressed by the kinase inhibitor staurosporine, suggesting that NO enhances [Ca(2+)](cyt) by promoting phosphorylation-dependent events. This result was further supported by the demonstration that the NO donor induced the activation of a 42-kDa protein kinase which belongs to SnRK2 families and corresponds to Nicotiana tabacum osmotic-stress-activated protein kinase (NtOSAK). Interestingly, NtOSAK was activated in response to hyperosmotic stress through a NO-dependent process, supporting the hypothesis that NO also promotes protein kinase activation during physiological processes.

  17. Two faces of Solanaceae telomeres: a comparison between Nicotiana and Cestrum telomeres and telomere-binding proteins.

    PubMed

    Peska, V; Sýkorová, E; Fajkus, J

    2008-01-01

    While most Solanaceae genera (e.g.Solanum, Nicotiana) possess Arabidopsis-type telomeres of (TTTAGGG)n maintained by telomerase, the genera Cestrum, Vestia and Sessea (Cestrum group) lack these telomeres. Here we show that in the Cestrum-group the activity of telomerase has been lost. Nevertheless, proteins binding the single-stranded G-rich strand of the Arabidopsis-type and related human-type (TTAGGG)n telomeric sequences are present in nuclear extracts of both Nicotiana and Cestrum species. These proteins may have a role in telomere function or other cellular activities. In addition to characterizing DNA binding specificity and molecular weights of these proteins, we searched in both N. tabacum (tobacco) and C. parqui for the presence of POT1-like proteins, involved in telomere capping and telomerase regulation. Analysis of POT1-like proteins available on public databases and cloned by us from C. parqui, revealed the N-terminal OB folds typical for this protein family and a novel, plant-specific conserved C-terminal OB-fold domain (CTOB). We propose that CTOB is involved in protein-protein interactions.

  18. Induction of systemic disease resistance in Nicotiana benthamiana by the cyclodipeptides cyclo (l-Pro-l-Pro) and cyclo (d-Pro-d-Pro).

    PubMed

    Wu, Liming; Wu, Huijun; Chen, Lina; Zhang, Hongyue; Gao, Xuewen

    2017-01-01

    Cyclodipeptides, formed from two amino acids by cyclodehydration, are produced naturally by many organisms, and are known to possess a large number of biological activities. In this study, we found that cyclo (l-Pro-l-Pro) and cyclo (d-Pro-d-Pro) (where Pro is proline) could induce defence responses and systemic resistance in Nicotiana benthamiana. Treatment with the two cyclodipeptides led to a reduction in disease severity by Phytophthora nicotianae and Tobacco mosaic virus (TMV) infections compared with controls. Both cyclopeptides triggered stomatal closure, induced reactive oxygen species production and stimulated cytosolic calcium ion and nitric oxide production in guard cells. In addition, the application of cyclodipeptides significantly up-regulated the expression of the plant defence gene PR-1a and the PR-1a protein, and increased cellular salicylic acid (SA) levels. These results suggest that the SA-dependent defence pathway is involved in cyclodipeptide-mediated pathogen resistance in N. benthamiana. We report the systemic resistance induced by cyclodipeptides, which sheds light on the potential of cyclodipeptides for the control of plant diseases.

  19. Plant surface reactions: an ozone defence mechanism impacting atmospheric chemistry

    NASA Astrophysics Data System (ADS)

    Jud, W.; Fischer, L.; Canaval, E.; Wohlfahrt, G.; Tissier, A.; Hansel, A.

    2015-07-01

    Elevated tropospheric ozone concentrations are considered a toxic threat to plants, responsible for global crop losses with associated economic costs of several billion dollars per year. Plant injuries have been linked to the uptake of ozone through stomatal pores and oxidative damage of the internal leaf tissue. But a striking question remains: how much ozone effectively enters the plant through open stomata and how much is lost by chemical reactions at the plant surface? In this laboratory study we could show that semi-volatile organic compounds exuded by the glandular trichomes of different Nicotiana tabacum varieties are an efficient ozone sink at the plant surface. In our experiments, different diterpenoid compounds were responsible for a strongly variety dependent ozone uptake of plants under dark conditions, when stomatal pores are almost closed. Surface reactions of ozone were accompanied by prompt release of oxygenated volatile organic compounds, which could be linked to the corresponding precursor compounds: ozonolysis of cis-abienol (C20H34O) - a diterpenoid with two exocyclic double bonds - caused emissions of formaldehyde (HCHO) and methyl vinyl ketone (C4H6O). The ring-structured cembratrien-diols (C20H34O2) with three endocyclic double bonds need at least two ozonolysis steps to form volatile carbonyls such as 4-oxopentanal (C5H8O2), which we could observe in the gas phase, too. Fluid dynamic calculations were used to model ozone distribution in the diffusion limited leaf boundary layer under daylight conditions. In the case of an ozone-reactive leaf surface, ozone gradients in the vicinity of stomatal pores are changed in such a way, that ozone flux through the open stomata is strongly reduced. Our results show that unsaturated semi-volatile compounds at the plant surface should be considered as a source of oxygenated volatile organic compounds, impacting gas phase chemistry, as well as efficient ozone sink improving the ozone tolerance of plants.

  20. In Defence of the Lecture

    ERIC Educational Resources Information Center

    Webster, R. Scott

    2015-01-01

    In response to the lecture format coming under "attack" and being replaced by online materials and smaller tutorials, this paper attempts to offer not only a defence but also to assert that the potential value of the lecture is difficult to replicate through other learning formats. Some of the criticisms against lectures will be…

  1. Pollination in Nicotiana alata stimulates synthesis and transfer to the stigmatic surface of NaStEP, a vacuolar Kunitz proteinase inhibitor homologue

    PubMed Central

    Busot, Grethel Yanet; McClure, Bruce; Ibarra-Sánchez, Claudia Patricia; Jiménez-Durán, Karina; Vázquez-Santana, Sonia; Cruz-García, Felipe

    2008-01-01

    After landing on a wet stigma, pollen grains hydrate and germination generally occurs. However, there is no certainty of the pollen tube growth through the style to reach the ovary. The pistil is a gatekeeper that evolved in many species to recognize and reject the self-pollen, avoiding endogamy and encouraging cross-pollination. However, recognition is a complex process, and specific factors are needed. Here the isolation and characterization of a stigma-specific protein from N. alata, NaStEP (N. alata Stigma Expressed Protein), that is homologous to Kunitz-type proteinase inhibitors, are reported. Activity gel assays showed that NaStEP is not a functional serine proteinase inhibitor. Immunohistochemical and protein blot analyses revealed that NaStEP is detectable in stigmas of self-incompatible (SI) species N. alata, N. forgetiana, and N. bonariensis, but not in self-compatible (SC) species N. tabacum, N. plumbaginifolia, N. benthamiana, N. longiflora, and N. glauca. NaStEP contains the vacuolar targeting sequence NPIVL, and immunocytochemistry experiments showed vacuolar localization in unpollinated stigmas. After self-pollination or pollination with pollen from the SC species N. tabacum or N. plumbaginifolia, NaStEP was also found in the stigmatic exudate. The synthesis and presence in the stigmatic exudate of this protein was strongly induced in N. alata following incompatible pollination with N. tabacum pollen. The transfer of NaStEP to the stigmatic exudate was accompanied by perforation of the stigmatic cell wall, which appeared to release the vacuolar contents to the apoplastic space. The increase in NaStEP synthesis after pollination and its presence in the stigmatic exudates suggest that this protein may play a role in the early pollen–stigma interactions that regulate pollen tube growth in Nicotiana. PMID:18689443

  2. The hydroxyproline-rich glycopeptide systemin precursor NapreproHypSys does not play a central role in Nicotiana attenuata's anti-herbivore defense responses.

    PubMed

    Berger, Beatrice; Baldwin, Ian T

    2007-11-01

    To determine whether the Nicotiana tabacum preproHypSys homolog in Nicotiana attenuata (NapreproHypSys) mediates anti-herbivore responses, we silenced (IRsys) and ectopically over-expressed (OVsys) NapreproHypSys in N. attenuata. Neither herbivore simulation nor methyl jasmonate (MeJA) application increased transcripts in wild-type (WT) or transformed lines. Compared to WT plants, OVsys plants had marginally higher constitutive levels but normally induced levels of trypsin proteinase inhibitors (TPIs) and nicotine; IRsys plants did not differ from WT plants. Herbivory-associated signalling [salicylic acid-induced protein kinase (SIPK) activity, jasmonic acid (JA), jasmonic acid-isoleucine/leucine (JA-Ile/Leu) and ethylene production or perception] did not differ strongly among the lines, but JA, JA-Ile/Leu and ethylene were marginally higher in OVsys plants. Manduca sexta larval performance did not differ among the lines, but feeding induced levels of TPI and nicotine in OVsys plants and decreased them in IRsys plants relative to WT. The secondary metabolite profiles of plants transplanted into N. attenuata's native habitat in the Great Basin Desert (UT, USA) mirrored those of glasshouse-grown plants, and compared to WT plants, OVsys plants suffered marginally less damage from grasshoppers, mirids and flea beetles but did not differ in their ability to attract Geocoris predators. We conclude that NapreproHypSys does not play a central role in anti-herbivore defense signalling in this native tobacco.

  3. RNA silencing suppression by plant pathogens: defence, counter-defence and counter-counter-defence.

    PubMed

    Pumplin, Nathan; Voinnet, Olivier

    2013-11-01

    RNA silencing is a central regulator of gene expression in most eukaryotes and acts both at the transcriptional level through DNA methylation and at the post-transcriptional level through direct mRNA interference mediated by small RNAs. In plants and invertebrates, the same pathways also function directly in host defence against viruses by targeting viral RNA for degradation. Successful viruses have consequently evolved diverse mechanisms to avoid silencing, most notably through the expression of viral suppressors of RNA silencing. RNA silencing suppressors have also been recently identified in plant pathogenic bacteria and oomycetes, suggesting that disruption of host silencing is a general virulence strategy across several kingdoms of plant pathogens. There is also increasing evidence that plants have evolved specific defences against RNA-silencing suppression by pathogens, providing yet another illustration of the never-ending molecular arms race between plant pathogens and their hosts.

  4. Human influence on the dispersal and genetic structure of French Globodera tabacum populations.

    PubMed

    Alenda, Charline; Montarry, Josselin; Grenier, Eric

    2014-10-01

    The dispersal abilities and the population genetic structure of nematodes living in soils are poorly known. In the present study, we have pursued these issues in the tobacco cyst nematode, Globodera tabacum, which is responsible of significant yield reductions. Nine microsatellites markers were used to explore the dispersal and genetic structure of 18 French G. tabacum populations. All the populations sampled belong to the "tabacum" subspecies and low level of gene flow was observed among G. tabacum populations in France. Bayesian genetic assignments revealed two distinct genetic groups that matched with the geographic limits of two agricultural cooperative societies. An important part of the genetic variability was observed between these agricultural cooperative societies and also within populations. Those results highlight the impact of the human organization of agricultural practices on the genetic structure of G. tabacum populations and complement previous results obtained on other cyst nematodes, showing the major contribution of human activities and soil transports during harvest in the passive dispersion of these organisms.

  5. Defence Capability Plan 2006-2016

    DTIC Science & Technology

    2006-06-14

    Version Points of Contact Phase 8B Capability Staff: Defence Materiel Organisation: Squadron Leader Greg Trott Ms Katrina Burzynski (02) 6265...Capability Plan 2006 – 2016 Public Version 0 Points of Contact Phase 7 Capability Staff: Defence Materiel Organisation: Major Paul Randall Mr Ross...Staff: Defence Materiel Organisation: Major Paul Randall Lieutenant Colonel Duncan Roach (02) 6265 4441 (03) 9282 5380 LAND 58 Phase 3 Weapon

  6. Australian Defence Force Demographic Data and Challenges

    DTIC Science & Technology

    2001-10-01

    AUSTRALIAN DEFENCE FORCE DEMOGRAPHIC DATA AND CHALLENGES Directorate of Strategic Personnel Planning and Research DSPPR Technical Note 10/2001...DATE 00 OCT 2001 2. REPORT TYPE N/A 3. DATES COVERED - 4. TITLE AND SUBTITLE Australian Defence Force Demographic Data and Challenges 5a...Prescribed by ANSI Std Z39-18 AUSTRALIAN DEFENCE FORCE DEMOGRAPHIC DATA AND CHALLENGES The findings and views expressed in this report are the results

  7. Defence Reporter. Summer/Autumn 2011

    DTIC Science & Technology

    2011-01-01

    defence science and technology literature. Defence Reporter is one part of a series of services and products produced by ATHENA to keep readers up ...To sign up for this free service, please send an e-mail with your full name and address details to: DefenceReporter@dstl.gov.uk. © Crown Copyright...methodological limitations. An alternative approach based on ‘bottom up ’ comparisons with existing platforms of similar capabilities is also described. In

  8. Plant defences against herbivore and insect attack

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plants deploy a number of defences against attack by insects and other herbivores. Direct defence is conferred by plant products and structures that deter or kill the herbivores. Chemical toxins and deterrents vary widely among plant species, and some typical toxins include alkaloids, terpenoids, st...

  9. Evolutionarily stable defence and signalling of that defence.

    PubMed

    Broom, M; Speed, M P; Ruxton, G D

    2006-09-07

    We examine the evolution and maintenance of defence and conspicuousness in prey species using a game theoretic model. In contrast to previous works, predators can raise as well as lower their attack probabilities as a consequence of encountering moderately defended prey. Our model predicts four distinct possibilities for evolutionarily stable strategies (ESSs) featuring maximum crypsis. Namely that such a solution can exist with (1) zero toxicity, (2) a non-zero but non-aversive level of toxicity, (3) a high, aversive level of toxicity or (4) that no such maximally cryptic solution exists. Maximally cryptic prey may still invest in toxins, because of the increased chance of surviving an attack (should they be discovered) that comes from having toxins. The toxin load of maximally cryptic prey may be sufficiently strong that the predators will find them aversive, and seek to avoid similar looking prey in future. However, this aversiveness does not always necessarily trigger aposematic signalling, and highly toxic prey can still be maximally cryptic, because the increased initial rate of attack from becoming more conspicuous is not necessarily always compensated for by increased avoidance of aversive prey by predators. In other circumstances, the optimal toxin load may be insufficient to generate aversion but still be non-zero (because it increases survival), and in yet other circumstances, it is optimal to make no investment in toxins at all. The model also predicts ESSs where the prey are highly defended and aversive and where this defence is advertised at a cost of increased conspicuousness to predators. In many circumstances there is an infinite array of these aposematic ESSs, where the precise appearance is unimportant as long as it is highly visible and shared by all members of the population. Yet another class of solutions is possible where there is strong between-individual variation in appearance between conspicuous, poorly defended prey.

  10. Transcriptional control of plant defence responses.

    PubMed

    Buscaill, Pierre; Rivas, Susana

    2014-08-01

    Mounting of efficient plant defence responses depends on the ability to trigger a rapid defence reaction after recognition of the invading microbe. Activation of plant resistance is achieved by modulation of the activity of multiple transcriptional regulators, both DNA-binding transcription factors and their regulatory proteins, that are able to reprogram transcription in the plant cell towards the activation of defence signalling. Here we provide an overview of recent developments on the transcriptional control of plant defence responses and discuss defence-related hormone signalling, the role of WRKY transcription factors during the regulation of plant responses to pathogens, nuclear functions of plant immune receptor proteins, as well as varied ways by which microbial effectors subvert plant transcriptional reprogramming to promote disease.

  11. Changes in photosynthetic metabolism induced by tobamovirus infection in Nicotiana benthamiana studied in vivo by thermoluminescence.

    PubMed

    Sajnani, Carlota; Zurita, Jorge L; Roncel, Mercedes; Ortega, José M; Barón, Matilde; Ducruet, Jean-Marc

    2007-01-01

    * In thylakoids from Nicotiana benthamiana infected with the pepper mild mottle virus (PMMoV), a decreased amount of the PsbP and PsbQ proteins of photosystem II and different proteins of the Calvin cycle have been previously observed. We used thermoluminescence to study the consequences in vivo. * Measurements on unfrozen discs from symptomatic and asymptomatic leaves of plants infected by two tobamovirus PMMoV-S and PMMoV-I strains were compared with homologous samples in control plants. * Thermoluminescence emission did not reveal noticeable alteration of PSII electron transfer activity in infected symptomatic leaves. In these leaves, the relative intensity of the 'afterglow' emission indicated an increase of the NADPH + ATP assimilatory potential, contrasting with its decrease in asymptomatic leaves. High-temperature thermoluminescence, as a result of peroxides, increased in symptomatic and asymptomatic leaves. * In young infected leaves, PSII activity is preserved, producing a high assimilatory potential. Older asymptomatic leaves export more nutrients towards young infected leaves. This depresses their assimilatory potential and weakens their defence mechanisms against reactive oxygen species, resulting in higher peroxide content.

  12. GhWRKY68 Reduces Resistance to Salt and Drought in Transgenic Nicotiana benthamiana

    PubMed Central

    Jia, Haihong; Wang, Chen; Wang, Fang; Liu, Shuchang; Li, Guilin; Guo, Xingqi

    2015-01-01

    The WRKY transcription factors modulate numerous physiological processes, including plant growth, development and responses to various environmental stresses. Currently, our understanding of the functions of the majority of the WRKY family members and their possible roles in signalling crosstalk is limited. In particular, very few WRKYs have been identified and characterised from an economically important crop, cotton. In this study, we characterised a novel group IIc WRKY gene, GhWRKY68, which is induced by different abiotic stresses and multiple defence-related signalling molecules. The β-glucuronidase activity driven by the GhWRKY68 promoter was enhanced after exposure to drought, salt, abscisic acid (ABA) and H2O2. The overexpression of GhWRKY68 in Nicotiana benthamiana reduced resistance to drought and salt and affected several physiological indices. GhWRKY68 may mediate salt and drought responses by modulating ABA content and enhancing the transcript levels of ABA-responsive genes. GhWRKY68-overexpressing plants exhibited reduced tolerance to oxidative stress after drought and salt stress treatments, which correlated with the accumulation of reactive oxygen species (ROS), reduced enzyme activities, elevated malondialdehyde (MDA) content and altered ROS-related gene expression. These results indicate that GhWRKY68 is a transcription factor that responds to drought and salt stresses by regulating ABA signalling and modulating cellular ROS. PMID:25793865

  13. A Phytophthora sojae cytoplasmic effector mediates disease resistance and abiotic stress tolerance in Nicotiana benthamiana.

    PubMed

    Zhang, Meixiang; Ahmed Rajput, Nasir; Shen, Danyu; Sun, Peng; Zeng, Wentao; Liu, Tingli; Juma Mafurah, Joseph; Dou, Daolong

    2015-06-03

    Each oomycete pathogen encodes a large number of effectors. Some effectors can be used in crop disease resistance breeding, such as to accelerate R gene cloning and utilisation. Since cytoplasmic effectors may cause acute physiological changes in host cells at very low concentrations, we assume that some of these effectors can serve as functional genes for transgenic plants. Here, we generated transgenic Nicotiana benthamiana plants that express a Phytophthora sojae CRN (crinkling and necrosis) effector, PsCRN115. We showed that its expression did not significantly affect the growth and development of N. benthamiana, but significantly improved disease resistance and tolerance to salt and drought stresses. Furthermore, we found that expression of heat-shock-protein and cytochrome-P450 encoding genes were unregulated in PsCRN115-transgenic N. benthamiana based on digital gene expression profiling analyses, suggesting the increased plant defence may be achieved by upregulation of these stress-related genes in transgenic plants. Thus, PsCRN115 may be used to improve plant tolerance to biotic and abiotic stresses.

  14. Periplasmic multilamellar membranous structures in Nicotiana tabacum L. pollen grains treated with Ni²⁺ or Cu²⁺.

    PubMed

    Polevova, Svetlana; Breygina, Maria; Matveyeva, Natalie; Yermakov, Igor

    2014-11-01

    Essential trace elements Ni(2+) and Cu(2+) can block pollen germination without causing cell death. Mechanisms of this effect remain unclear. Using TEM, we studied the effects of Ni(2+) or Cu(2+) treatment on the ultrastructure of the aperture regions in tobacco pollen preparing to germinate in vitro, since in these zones, the main fluxes of water, ions, and metabolites cross the plasmalemma. Neither Ni(2+) nor Cu(2+) altered the cytoplasm ultrastructure, but both affected the reorganization of apertural periplasm during pollen activation. Numerous multilamellar membranous structures continuous with the plasma membrane could be seen in hydrated but not yet activated pollen. When the normal activation was completed, the structures disappeared and the plasmalemma became smooth. In the presence of 1 mM Ni(2+) or 100 μM Cu(2+), these structures preserved its original appearance. It is assumed to be the storage form for the membrane material, which is to provide an initial phase of the pollen tube growth. Ni(2+) and Cu(2+) affect the utilization of these membranes, thereby, blocking the pollen germination.

  15. Alternation of light/dark period priming enhances clomazone tolerance by increasing the levels of ascorbate and phenolic compounds and ROS detoxification in tobacco (Nicotiana tabacum L.) plantlets.

    PubMed

    Darwish, Majd; Lopez-Lauri, Félicie; Vidal, Véronique; El Maâtaoui, Mohamed; Sallanon, Huguette

    2015-07-01

    The effect of the alternation of light/dark periods (AL) (16/8 min light/dark cycles and a photosynthetic photon flux density (PPFD) of 50 μmol photons m(-2) s(-1) for three days) to clarify the mechanisms involved in the clomazone tolerance of tobacco plantlets primed with AL was studied. Clomazone decreased PSII activity, the net photosynthetic rate (Pn), and the ascorbate and total polyphenol contents and increased H2O2 and starch grain accumulation and the number of the cells that underwent programmed cell death (PCD). The pretreatment with AL reduced the inhibitory effect of clomazone on the PSII activity and photosynthesis, as indicated by the decreases in the H2O2 and starch grain accumulation and the PCD levels, and increased the content of ascorbate and certain phenolic compounds, such as chlorogenic acid, neochlorogenic acid and rutin. The AL treatment could promote photorespiration via post-illumination burst (PIB) effects. This alternative photorespiratory electron pathway may reduce H2O2 generation via the consumption of photochemical energy, such as NADH+H(+). At 10 days (D10) of AL treatment, this process induced moderate stress which stimulates H2O2 detoxification systems by increasing the activity of antioxidant enzymes and the biosynthesis of antioxidant components. Therefore, the PCD levels provoked by clomazone were noticeably decreased.

  16. Validation of a GC-FID method for rapid quantification of nicotine in fermented extracts prepared from Nicotiana tabacum fresh leaves and studies of nicotine metabolites.

    PubMed

    Millet, Agnès; Stintzing, Florian; Merfort, Irmgard

    2009-07-12

    A new GC-FID method, which allows rapid and reliable quantitation of nicotine in tobacco leaf extracts, was developed and validated. To avoid nicotine adsorption on the column, an amine-deactivated capillary column was used. The method developed was applied to study the degradation of nicotine in a fermented aqueous extract, and a loss of nearly 20% of nicotine over 12 months was observed. Careful inspection of GC-MS runs from concentrated samples of the same extract revealed the presence of nicotine metabolites such as nornicotine, anatabine, myosmine, 2,3'-bipyridyl, and 2-pyrrolidinone.

  17. CDPK1 from ginger promotes salinity and drought stress tolerance without yield penalty by improving growth and photosynthesis in Nicotiana tabacum.

    PubMed

    Vivek, Padmanabhan Jayanthi; Tuteja, Narendra; Soniya, Eppurathu Vasudevan

    2013-01-01

    In plants, transient changes in calcium concentrations of cytosol have been observed during stress conditions like high salt, drought, extreme temperature and mechanical disturbances. Calcium-dependent protein kinases (CDPKs) play important roles in relaying these calcium signatures into downstream effects. In this study, a stress-responsive CDPK gene, ZoCDPK1 was isolated from a stress cDNA generated from ginger using rapid amplification of cDNA ends (RLM-RACE) - PCR technique and characterized its role in stress tolerance. An important aspect seen during the analysis of the deduced protein is a rare coupling between the presence of a nuclear localization sequence in the junction domain and consensus sequence in the EF-hand loops of calmodulin-like domain. ZoCDPK1 is abundantly expressed in rhizome and is rapidly induced by high-salt stress, drought, and jasmonic acid treatment but not by low temperature stress or abscissic acid treatment. The sub-cellular localization of ZoCDPK1-GFP fusion protein was studied in transgenic tobacco epidermal cells using confocal laser scanning microscopy. Over-expression of ginger CDPK1 gene in tobacco conferred tolerance to salinity and drought stress as reflected by the high percentage of seed germination, higher relative water content, expression of stress responsive genes, higher leaf chlorophyll content, increased photosynthetic efficiency and other photosynthetic parameters. In addition, transgenic tobacco subjected to salinity/drought stress exhibited 50% more growth during stress conditions as compared to wild type plant during normal conditions. T3 transgenic plants are able to grow to maturity, flowers early and set viable seeds under continuous salinity or drought stress without yield penalty. The ZoCDPK1 up-regulated the expression levels of stress-related genes RD21A and ERD1 in tobacco plants. These results suggest that ZoCDPK1 functions in the positive regulation of the signaling pathways that are involved in the response to salinity and drought stress in ginger and it is likely operating in a DRE/CRT independent manner.

  18. Silencing S-Adenosyl-L-Methionine Decarboxylase (SAMDC) in Nicotiana tabacum Points at a Polyamine-Dependent Trade-Off between Growth and Tolerance Responses

    PubMed Central

    Mellidou, Ifigeneia; Moschou, Panagiotis N.; Ioannidis, Nikolaos E.; Pankou, Chryssa; Gėmes, Katalin; Valassakis, Chryssanthi; Andronis, Efthimios A.; Beris, Despoina; Haralampidis, Kosmas; Roussis, Andreas; Karamanoli, Aikaterini; Matsi, Theodora; Kotzabasis, Kiriakos; Constantinidou, Helen-Isis; Roubelakis-Angelakis, Kalliopi A.

    2016-01-01

    Polyamines (PAs) are nitrogenous molecules that are indispensable for cell viability and with an agreed-on role in the modulation of stress responses. Tobacco plants with downregulated SAMDC (AS-SAMDC) exhibit reduced PAs synthesis but normal levels of PA catabolism. We used AS-SAMDC to increase our understanding on the role of PAs in stress responses. Surprisingly, at control conditions AS-SAMDC plants showed increased biomass and altered developmental characteristics, such as increased height and leaf number. On the contrary, during salt stress AS-SAMDC plants showed reduced vigor when compared to the WT. During salt stress, the AS-SAMDC plants although showing compensatory readjustments of the antioxidant machinery and of photosynthetic apparatus, they failed to sustain their vigor. AS-SAMDC sensitivity was accompanied by inability to effectively control H2O2 levels and concentrations of monovalent and divalent cations. In accordance with these findings, we suggest that PAs may regulate the trade-off between growth and tolerance responses. PMID:27064210

  19. CbCBF from Capsella bursa-pastoris enhances cold tolerance and restrains growth in Nicotiana tabacum by antagonizing with gibberellin and affecting cell cycle signaling.

    PubMed

    Zhou, Mingqi; Xu, Ming; Wu, Lihua; Shen, Chen; Ma, Hong; Lin, Juan

    2014-06-01

    Plant cells respond to cold stress via a regulatory mechanism leading to enhanced cold acclimation accompanied by growth retardation. The C-repeat binding factor (CBF) signaling pathway is essential for cold response of flowering plants. Our previously study documented a novel CBF-like gene from the cold-tolerant Capsella bursa-pastoris named CbCBF, which was responsive to chilling temperatures. Here, we show that CbCBF expression is obviously responsive to chilling, freezing, abscisic acid, gibberellic acid (GA), indoleacetic acid or methyl jasmonate treatments and that the CbCBF:GFP fusion protein was localized to the nucleus. In addition, CbCBF overexpression conferred to the cold-sensitive tobacco plants enhanced tolerance to chilling and freezing, as well as dwarfism and delayed flowering. The leaf cells of CbCBF overexpression tobacco lines attained smaller sizes and underwent delayed cell division with reduced expression of cyclin D genes. The dwarfism of CbCBF transformants can be partially restored by GA application. Consistently, CbCBF overexpression reduced the bioactive gibberellin contents and disturbed the expression of gibberellin metabolic genes in tobacco. Meanwhile, cold induced CbCBF expression and cold tolerance in C. bursa-pastoris are reduced by GA. We conclude that CbCBF confers cold resistance and growth inhibition to tobacco cells by interacting with gibberellin and cell cycle pathways, likely through activation of downstream target genes.

  20. Functional analysis of the Sesbania rostrata leghemoglobin glb3 gene 5'-upstream region in transgenic Lotus corniculatus and Nicotiana tabacum plants.

    PubMed

    Szabados, L; Ratet, P; Grunenberg, B; de Bruijn, F J

    1990-10-01

    Expression of the Sesbania rostrata leghemoglobin glb3 gene was analyzed in transgenic Lotus corniculatus and tobacco plants harboring chimeric glb3-uidA (gus) gene fusions to identify cis-acting elements involved in nodule-specific gene expression and general transcriptional control. A 1.9-kilobase fragment of the glb3 5'-upstream region was found to direct a high level of nodule-specific beta-glucuronidase (GUS) activity in L. corniculatus, restricted to the Rhizobium-infected cells of the nodules. The same fragment directed a low level of GUS activity in tobacco, restricted primarily to the roots and to phloem cells of the stem and petiole vascular system. A deletion analysis revealed that the region between coordinates -429 and -48 relative to the ATG was sufficient for nodule-specific expression. Replacement of the -161 to -48 region, containing the glb3 CAAT and TATA boxes, with the heterologous truncated promoters delta-p35S and delta-pnos resulted in a loss of nodule specificity and reduction of GUS activity in L. corniculatus but a significant increase in tobacco, primarily in the roots. The same fragment could not direct nodule-specific expression when fused to a heterologous enhancer in cis. This region contains DNA sequences required, but not sufficient, for nodule-specific expression in L. corniculatus that function poorly or may be involved in promoter silencing in tobacco. By fusing further upstream fragments to the delta-p35S and delta-pnos promoters, two positive regulatory regions were delimited between coordinates -1601 and -670, as well as -429 and -162. The former region appears to function as a general enhancer because it significantly increased promoter activity in both orientations in L. corniculatus and tobacco. The latter region could enhance gene expression in both orientations in tobacco, but only in the correct orientation in L. corniculatus. These results show that efficient expression of the S. rostrata glb3 gene in nodules is mediated by an ATG-proximal, tissue-specific element, as well as further 5'-upstream positive elements; that the S. rostrata glb3 promoter is induced in a nodule-specific fashion in the heterologous legume L. corniculatus, suggesting a high degree of conservation of the relevant regulatory signals; and that the S. rostrata lb promoter is not silent in the nonlegume tobacco, but is expressed primarily in the roots.

  1. Alternative splicing of basic chitinase gene PR3b in the low-nicotine mutants of Nicotiana tabacum L. cv. Burley 21

    PubMed Central

    Ma, Haoran; Wang, Feng; Wang, Wenjing; Yin, Guoying; Zhang, Dingyu; Ding, Yongqiang; Timko, Michael P.; Zhang, Hongbo

    2016-01-01

    Two unlinked semi-dominant loci, A (NIC1) and B (NIC2), control nicotine and related alkaloid biosynthesis in Burley tobaccos. Mutations in either or both loci (nic1 and nic2) lead to low nicotine phenotypes with altered environmental stress responses. Here we show that the transcripts derived from the pathogenesis-related (PR) protein gene PR3b are alternatively spliced to a greater extent in the nic1 and nic2 mutants of Burley 21 tobacco and the nic1nic2 double mutant. The alternative splicing results in a deletion of 65 nucleotides and introduces a premature stop codon into the coding region of PR3b that leads to a significant reduction of PR3b specific chitinase activity. Assays of PR3b splicing in F2 individuals derived from crosses between nic1 and nic2 mutants and wild-type plants showed that the splicing phenotype is controlled by the NIC1 and NIC2 loci, even though NIC1 and NIC2 are unlinked loci. Moreover, the transcriptional analyses showed that the splicing patterns of PR3b in the low-nicotine mutants were differentially regulated by jasmonate (JA) and ethylene (ET). These data suggest that the NIC1 and NIC2 loci display differential roles in regulating the alternative splicing of PR3b in Burley 21. The findings in this study have provided valuable information for extending our understanding of the broader effects of the low-nicotine mutants of Burley 21 and the mechanism by which JA and ET signalling pathways post-transcriptionally regulate the activity of PR3b protein. PMID:27664270

  2. Increased Nicotiana tabacum fitness through positive regulation of carotenoid, gibberellin and chlorophyll pathways promoted by Daucus carota lycopene β-cyclase (Dclcyb1) expression.

    PubMed

    Moreno, J C; Cerda, A; Simpson, K; Lopez-Diaz, I; Carrera, E; Handford, M; Stange, C

    2016-04-01

    Carotenoids, chlorophylls and gibberellins are derived from the common precursor geranylgeranyl diphosphate (GGPP). One of the enzymes in carotenoid biosynthesis is lycopene β-cyclase (LCYB) that catalyzes the conversion of lycopene into β-carotene. In carrot, Dclcyb1 is essential for carotenoid synthesis in the whole plant. Here we show that when expressed in tobacco, increments in total carotenoids, β-carotene and chlorophyll levels occur. Furthermore, photosynthetic efficiency is enhanced in transgenic lines. Interestingly, and contrary to previous observations where overexpression of a carotenogenic gene resulted in the inhibition of the synthesis of gibberellins, we found raised levels of active GA4 and the concommitant increases in plant height, leaf size and whole plant biomass, as well as an early flowering phenotype. Moreover, a significant increase in the expression of the key carotenogenic genes, Ntpsy1, Ntpsy2 and Ntlcyb, as well as those involved in the synthesis of chlorophyll (Ntchl), gibberellin (Ntga20ox, Ntcps and Ntks) and isoprenoid precursors (Ntdxs2 and Ntggpps) was observed. These results indicate that the expression of Dclcyb1 induces a positive feedback affecting the expression of isoprenoid gene precursors and genes involved in carotenoid, gibberellin and chlorophyll pathways leading to an enhancement in fitness measured as biomass, photosynthetic efficiency and carotenoid/chlorophyll composition.

  3. Enhancing tonoplast Cd/H antiport activity increases Cd, Zn, and Mn tolerance, and impacts root/shoot Cd partitioning in Nicotiana tabacum L.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sequestration mechanisms that prevent high concentrations of free metal ions from persisting in metabolically active compartments of cells are thought to be central in tolerance of plants to high levels of divalent cation metals. Expression of "AtCAX2" or "AtCAX4", which encode divalent cation/proto...

  4. RNA interference of the nicotine demethylase gene CYP82E4v1 reduces nornicotine content and enhances Myzus persicae resistance in Nicotiana tabacum L.

    PubMed

    Zhao, Dan; Qin, Li-Jun; Zhao, De-Gang

    2016-10-01

    The CYP82E4v1 gene was identified to encode nicotine demethylase, which catalyzed the conversion of nicotine to nornicotine. In this study, we constructed CYP82E4v1-RNAi vector and genetically transformed tobacco variety K326. The determination results of nicotine and nornicotine content via HPLC demonstrated that there was significant increase of nicotine content and reduction of nornicotine content in transgenic plants compared with those in wild-type plants. Exogenous application of IAA or GA3 could reduce the nicotine content in tobaccos, while ABA or 6-BA could increase the content of nicotine. And the more significant difference of nicotine content change in transgenic plants. Aphid-inoculation experiment demonstrated the number of aphid population in transgenic plants was significantly lower than wild-type plants at 12 d after aphid-inoculation. Meanwhile, the activity of AOEs and PAL in transgenic and wild-type tobacco plants after aphid-inoculation was measured. At 3 d after aphid-inoculation, both AOEs and PAL activity were significantly higher than controls, including wild-type plants with aphid-inoculation and transgenic plants with mock-inoculation. Also, the relative expression of these genes involved in salicylic acid/jasmonic acid (SA/JA) signaling pathways was analyzed at different stages after aphid-inoculation and the results demonstrated that there was significantly higher expression of JA-induced LOX gene in both transgenic and wild-type plants inoculated by aphid than the non-inoculated ones while no significant difference in the expression of SA-induced PR-1a gene among them was found, which indicated the JA-mediated resistance response was activated during aphid infestation. Moreover, although the expression level of BGL (another JA-induced gene) was less significant between the two inoculated tobaccos, it was significantly higher than the plant without inoculation, which was 1.4 and 2.2 folds higher than the non-inoculated controls respectively. To sum up, the improvement of aphid-resistance in transgenic tobaccos was based on nicotine accumulation which might cause nerve and antifeed toxicity and JA-mediated resistance response by enhancing the activities of AOEs and PAL.

  5. Increased Nicotiana tabacum fitness through positive regulation of carotenoid, gibberellin and chlorophyll pathways promoted by Daucus carota lycopene β-cyclase (Dclcyb1) expression

    PubMed Central

    Moreno, J.C.; Cerda, A.; Simpson, K.; Lopez-Diaz, I.; Carrera, E; Handford, M.; Stange, C.

    2016-01-01

    Carotenoids, chlorophylls and gibberellins are derived from the common precursor geranylgeranyl diphosphate (GGPP). One of the enzymes in carotenoid biosynthesis is lycopene β-cyclase (LCYB) that catalyzes the conversion of lycopene into β-carotene. In carrot, Dclcyb1 is essential for carotenoid synthesis in the whole plant. Here we show that when expressed in tobacco, increments in total carotenoids, β-carotene and chlorophyll levels occur. Furthermore, photosynthetic efficiency is enhanced in transgenic lines. Interestingly, and contrary to previous observations where overexpression of a carotenogenic gene resulted in the inhibition of the synthesis of gibberellins, we found raised levels of active GA4 and the concommitant increases in plant height, leaf size and whole plant biomass, as well as an early flowering phenotype. Moreover, a significant increase in the expression of the key carotenogenic genes, Ntpsy1, Ntpsy2 and Ntlcyb, as well as those involved in the synthesis of chlorophyll (Ntchl), gibberellin (Ntga20ox, Ntcps and Ntks) and isoprenoid precursors (Ntdxs2 and Ntggpps) was observed. These results indicate that the expression of Dclcyb1 induces a positive feedback affecting the expression of isoprenoid gene precursors and genes involved in carotenoid, gibberellin and chlorophyll pathways leading to an enhancement in fitness measured as biomass, photosynthetic efficiency and carotenoid/chlorophyll composition. PMID:26893492

  6. CDPK1 from Ginger Promotes Salinity and Drought Stress Tolerance without Yield Penalty by Improving Growth and Photosynthesis in Nicotiana tabacum

    PubMed Central

    Vivek, Padmanabhan Jayanthi; Tuteja, Narendra; Soniya, Eppurathu Vasudevan

    2013-01-01

    In plants, transient changes in calcium concentrations of cytosol have been observed during stress conditions like high salt, drought, extreme temperature and mechanical disturbances. Calcium-dependent protein kinases (CDPKs) play important roles in relaying these calcium signatures into downstream effects. In this study, a stress-responsive CDPK gene, ZoCDPK1 was isolated from a stress cDNA generated from ginger using rapid amplification of cDNA ends (RLM-RACE) – PCR technique and characterized its role in stress tolerance. An important aspect seen during the analysis of the deduced protein is a rare coupling between the presence of a nuclear localization sequence in the junction domain and consensus sequence in the EF-hand loops of calmodulin-like domain. ZoCDPK1 is abundantly expressed in rhizome and is rapidly induced by high-salt stress, drought, and jasmonic acid treatment but not by low temperature stress or abscissic acid treatment. The sub-cellular localization of ZoCDPK1-GFP fusion protein was studied in transgenic tobacco epidermal cells using confocal laser scanning microscopy. Over-expression of ginger CDPK1 gene in tobacco conferred tolerance to salinity and drought stress as reflected by the high percentage of seed germination, higher relative water content, expression of stress responsive genes, higher leaf chlorophyll content, increased photosynthetic efficiency and other photosynthetic parameters. In addition, transgenic tobacco subjected to salinity/drought stress exhibited 50% more growth during stress conditions as compared to wild type plant during normal conditions. T3 transgenic plants are able to grow to maturity, flowers early and set viable seeds under continuous salinity or drought stress without yield penalty. The ZoCDPK1 up-regulated the expression levels of stress-related genes RD21A and ERD1 in tobacco plants. These results suggest that ZoCDPK1 functions in the positive regulation of the signaling pathways that are involved in the response to salinity and drought stress in ginger and it is likely operating in a DRE/CRT independent manner. PMID:24194837

  7. Molecular heterogeneity of photosystem I. psaD, psaE, psaF, psaH, and psaL are all present in isoforms in Nicotiana spp.

    PubMed

    Obokata, J; Mikami, K; Hayashida, N; Nakamura, M; Sugiura, M

    1993-08-01

    The protein composition of photosystem I (PSI) was examined in Nicotiana spp. by high-resolution polyacrylamide gel electrophoresis, N-terminal amino acid sequencing, and immunoblot analysis. Five PSI proteins show polymorphism in an amphidiploid species, Nicotiana tabacum, but not in its ancestral diploid species, Nicotiana sylvestris and Nicotiana tomentosiformis. These Nicotiana spp. appear to have at least 18 PSI proteins per genome that range in molecular mass from 3 to 20 kD. They include the products of nuclear genes psaD, psaE, psaF, psaG, psaH, psaK, and psaL, the product of chloroplast gene psaC, N-terminally blocked proteins of 4.5 and 3.0 kD, and an unidentified protein of 12.5 kD. The psaD, psaF, psaH, and psaL products have two isoforms each that are distinguished by different mobilities in polyacrylamide gel electrophoresis, and the psaE product has four isoforms. The two isoforms of the psaD product have distinct amino acid sequences, indicating that they are encoded by different genes within the genome. Four isoforms of the psaE products can be classified into two groups by N-terminal amino acid sequence, indicating that at least two psaE genes are present in the genome. To examine whether the polymorphic nature of PSI is peculiar to Nicotiana spp., we carried out immunoblot analysis of the psaD and psaE products in isogenic lines of tomato (Lycopersicon esculentum), Arabidopsis thaliana, red bean (Vigna angularis), and corn (Zea mays). Two electrophoretically distinct isoforms were found for the psaD products of tomato, A. thaliana, and corn, and two isoforms of psaE products were detected in tomato, A. thaliana, and red bean. These results suggest that the nuclear-encoded subunits of PSI, except for the psaG and psaK products, generally have two isoforms.

  8. Functional analysis reveals effects of tobacco alternative oxidase gene (NtAOX1a) on regulation of defence responses against abiotic and biotic stresses.

    PubMed

    Zhang, Yi; Xi, Dongmei; Wang, Jian; Zhu, Dongfang; Guo, Xingqi

    2009-07-22

    Mitochondrial AOX (alternative oxidase) is the terminal oxidase of the CN (cyanide)-resistant alternative respiratory pathway in plants. To investigate the role of the tobacco AOX gene (NtAOX1a) (where Nt is Nicotiana tabacum) under deleterious conditions which could induce ROS (reactive oxygen species) accumulation, we generated and characterized a number of independent transgenic tobacco (N. tabacum) lines with altered NtAOX1a gene expression and AP (alternative pathway) capacity. AOX efficiently inhibited the production of low-temperature-induced H2O2 and might be a major enzyme for scavenging H2O2 at low temperature. Furthermore, NtAOX1a may act as a regulator of KCN-induced resistance to TMV (tobacco mosaic virus) through the regulation of H2O2. Notably, a moderate accumulation of H2O2 under the control of NtAOX1a was crucial in viral resistance. Analysis of seed germination indicated an important role for NtAOX1a in germination under H2O2-induced oxidative stress when the CP (cytochrome pathway) was inhibited. These results demonstrate that NtAOX1a is necessary for plants to survive low temperature, pathogen attack and oxidative stress by scavenging ROS under these adverse conditions when the CP is restricted.

  9. The mechanical defence advantage of small seeds.

    PubMed

    Fricke, Evan C; Wright, S Joseph

    2016-08-01

    Seed size and toughness affect seed predators, and size-dependent investment in mechanical defence could affect relationships between seed size and predation. We tested how seed toughness and mechanical defence traits (tissue density and protective tissue content) are related to seed size among tropical forest species. Absolute toughness increased with seed size. However, smaller seeds had higher specific toughness both within and among species, with the smallest seeds requiring over 2000 times more energy per gram to break than the largest seeds. Investment in mechanical defence traits varied widely but independently of the toughness-mass allometry. Instead, a physical scaling relationship confers a toughness advantage on small seeds independent of selection on defence traits and without a direct cost. This scaling relationship may contribute to seed size diversity by decreasing fitness differences among large and small seeds. Allometric scaling of toughness reconciles predictions and conflicting empirical relationships between seed size and predation.

  10. Public Private Partnerships Applicability to Defence Procurement

    DTIC Science & Technology

    2001-09-01

    Public Private Partnerships Applicability to Defence Procurement Jonathan Barnes KPMG Corporate Finance Report Documentation Page Report Date...25SEP2001 Report Type N/A Dates Covered (from... to) 25SEP2001 - 27SEP2001 Title and Subtitle Public Private Partnerships Applicability to Defence...unclassified Classification of Abstract unclassified Limitation of Abstract UU Number of Pages 6 kpmg Aim Provide an appreciation of: n Public Private Partnerships

  11. Calcium in plant defence-signalling pathways.

    PubMed

    Lecourieux, David; Ranjeva, Raoul; Pugin, Alain

    2006-01-01

    In plant cells, the calcium ion is a ubiquitous intracellular second messenger involved in numerous signalling pathways. Variations in the cytosolic concentration of Ca2+ ([Ca2+]cyt) couple a large array of signals and responses. Here we concentrate on calcium signalling in plant defence responses, particularly on the generation of the calcium signal and downstream calcium-dependent events participating in the establishment of defence responses with special reference to calcium-binding proteins.

  12. The Harbour Defence IKC2 Experience

    DTIC Science & Technology

    2005-06-01

    Choon Kiat, Tan Defence Science and Technolgy Agency 1 Depot Road #22-01 DefenceTechnology Tower A Singapore 109679 Phone : +65 63732338 Fax...Command Post (Desktop) Mobile Units (PDA) Radar 1 Web Service Radar 2 Web Service Radar 1 Tracks Msg Radar 2 Tracks Msg Web Service Abstraction...was found to be adequate for the mobile forces, providing a relatively constant throughput of 8 kbps throughout the base, though minor service

  13. Host defences against Giardia lamblia.

    PubMed

    Lopez-Romero, G; Quintero, J; Astiazarán-García, H; Velazquez, C

    2015-08-01

    Giardia spp. is a protozoan parasite that inhabits the upper small intestine of mammals and other species and is the aetiological agent of giardiasis. It has been demonstrated that nitric oxide, mast cells and dendritic cells are the first line of defence against Giardia. IL-6 and IL-17 play an important role during infection. Several cytokines possess overlapping functions in regulating innate and adaptive immune responses. IgA and CD4(+) T cells are fundamental to the process of Giardia clearance. It has been suggested that CD4(+) T cells play a double role during the anti-Giardia immune response. First, they activate and stimulate the differentiation of B cells to generate Giardia-specific antibodies. Second, they act through a B-cell-independent mechanism that is probably mediated by Th17 cells. Several Giardia proteins that stimulate humoral and cellular immune responses have been described. Variant surface proteins, α-1 giardin, and cyst wall protein 2 can induce host protective responses to future Giardia challenges. The characterization and evaluation of the protective potential of the immunogenic proteins that are associated with Giardia will offer new insights into host-parasite interactions and may aid in the development of an effective vaccine against the parasite.

  14. Intraspecific Variability within Globodera tabacum solanacearum Using Random Amplified Polymorphic DNA

    PubMed Central

    Syracuse, A. J.; Johnson, C. S.; Eisenback, J. D.; Nessler, C. L.; Smith, E. P.

    2004-01-01

    Random amplified polymorphic DNA (RAPDs) were used to investigate the intraspecific variability among 19 geographic isolates of Globodera tabacum solanacearum from eight counties in Virginia and one county in North Carolina. Globodera tabacum tabacum, G. t. virginiae, and the Mexican cyst nematode (MCN) were included as outgroups. Six primers were used and 119 amplification products were observed. Each primer yielded reproducible differences in fragment patterns that differentiated the isolates and species. Hierarchical cluster analysis was performed to illustrate the relatedness among isolates and species. The average Jaccard's similarity index among isolates of G. t. solanacearum was 74%, possibly representing greater variation than that reported in the literature across different pathotypes of the potato cyst nematode, Globodera pallida, in studies where RAPD were also employed. The RAPD markers described here may be useful for the development of specific primers or probes that could improve the identification of TCN populations. Such improvements in the characterization of TCN genotypes would facilitate the effective deployment of existing and future resistant cultivars to control these economically important pests. PMID:19262823

  15. Heterologous Expression of Moss Light-harvesting Complex Stress-related 1 (LHCSR1), the Chlorophyll a-Xanthophyll Pigment-protein Complex Catalyzing Non-photochemical Quenching, in Nicotiana sp.*

    PubMed Central

    Pinnola, Alberta; Ghin, Leonardo; Gecchele, Elisa; Merlin, Matilde; Alboresi, Alessandro; Avesani, Linda; Pezzotti, Mario; Capaldi, Stefano; Cazzaniga, Stefano; Bassi, Roberto

    2015-01-01

    Oxygenic photosynthetic organisms evolved mechanisms for thermal dissipation of energy absorbed in excess to prevent formation of reactive oxygen species. The major and fastest component, called non-photochemical quenching, occurs within the photosystem II antenna system by the action of two essential light-harvesting complex (LHC)-like proteins, photosystem II subunit S (PSBS) in plants and light-harvesting complex stress-related (LHCSR) in green algae and diatoms. In the evolutionary intermediate Physcomitrella patens, a moss, both gene products are active. These proteins, which are present in low amounts, are difficult to purify, preventing structural and functional analysis. Here, we report on the overexpression of the LHCSR1 protein from P. patens in the heterologous systems Nicotiana benthamiana and Nicotiana tabacum using transient and stable nuclear transformation. We show that the protein accumulated in both heterologous systems is in its mature form, localizes in the chloroplast thylakoid membranes, and is correctly folded with chlorophyll a and xanthophylls but without chlorophyll b, an essential chromophore for plants and algal LHC proteins. Finally, we show that recombinant LHCSR1 is active in quenching in vivo, implying that the recombinant protein obtained is a good material for future structural and functional studies. PMID:26260788

  16. Do strigolactones contribute to plant defence?

    PubMed

    Torres-Vera, Rocío; García, Juan M; Pozo, María J; López-Ráez, Juan A

    2014-02-01

    Strigolactones are multifunctional molecules involved in several processes outside and within the plant. As signalling molecules in the rhizosphere, they favour the establishment of arbuscular mycorrhizal symbiosis, but they also act as host detection cues for root parasitic plants. As phytohormones, they are involved in the regulation of plant architecture, adventitious rooting, secondary growth and reproductive development, and novel roles are emerging continuously. In the present study, the possible involvement of strigolactones in plant defence responses was investigated. For this purpose, the resistance/susceptibility of the strigolactone-deficient tomato mutant Slccd8 against the foliar fungal pathogens Botrytis cinerea and Alternaria alternata was assessed. Slccd8 was more susceptible to both pathogens, pointing to a new role for strigolactones in plant defence. A reduction in the content of the defence-related hormones jasmonic acid, salicylic acid and abscisic acid was detected by high-performance liquid chromatography coupled to tandem mass spectrometry in the Slccd8 mutant, suggesting that hormone homeostasis is altered in the mutant. Moreover, the expression level of the jasmonate-dependent gene PinII, involved in the resistance of tomato to B. cinerea, was lower than in the corresponding wild-type. We propose here that strigolactones play a role in the regulation of plant defences through their interaction with other defence-related hormones, especially with the jasmonic acid signalling pathway.

  17. Pepper aldehyde dehydrogenase CaALDH1 interacts with Xanthomonas effector AvrBsT and promotes effector-triggered cell death and defence responses.

    PubMed

    Kim, Nak Hyun; Hwang, Byung Kook

    2015-06-01

    Xanthomonas type III effector AvrBsT induces hypersensitive cell death and defence responses in pepper (Capsicum annuum) and Nicotiana benthamiana. Little is known about the host factors that interact with AvrBsT. Here, we identified pepper aldehyde dehydrogenase 1 (CaALDH1) as an AvrBsT-interacting protein. Bimolecular fluorescence complementation and co-immunoprecipitation assays confirmed the interaction between CaALDH1 and AvrBsT in planta. CaALDH1:smGFP fluorescence was detected in the cytoplasm. CaALDH1 expression in pepper was rapidly and strongly induced by avirulent Xanthomonas campestris pv. vesicatoria (Xcv) Ds1 (avrBsT) infection. Transient co-expression of CaALDH1 with avrBsT significantly enhanced avrBsT-triggered cell death in N. benthamiana leaves. Aldehyde dehydrogenase activity was higher in leaves transiently expressing CaALDH1, suggesting that CaALDH1 acts as a cell death enhancer, independently of AvrBsT. CaALDH1 silencing disrupted phenolic compound accumulation, H2O2 production, defence response gene expression, and cell death during avirulent Xcv Ds1 (avrBsT) infection. Transgenic Arabidopsis thaliana overexpressing CaALDH1 exhibited enhanced defence response to Pseudomonas syringae pv. tomato and Hyaloperonospora arabidopsidis infection. These results indicate that cytoplasmic CaALDH1 interacts with AvrBsT and promotes plant cell death and defence responses.

  18. Characterization of Cercospora nicotianae Hypothetical Proteins in Cercosporin Resistance

    PubMed Central

    Beseli, Aydin; Noar, Roslyn; Daub, Margaret E.

    2015-01-01

    The photoactivated toxin, cercosporin, produced by Cercospora species, plays an important role in pathogenesis of this fungus to host plants. Cercosporin has almost universal toxicity to cells due to its production of reactive oxygen species including singlet oxygen. For that reason, Cercospora species, which are highly resistant to their own toxin, are good candidates to identify genes for resistance to cercosporin and to the reactive oxygen species it produces. In previous research, the zinc cluster transcription factor CRG1 (cercosporin resistance gene 1) was found to be crucial for Cercospora species’ resistance against cercosporin, and subtractive hybridization analysis identified 185 genes differentially expressed between Cercospora nicotianae wild type (wt) and a crg1 mutant. The focus of this work was to identify and characterize the hypothetical proteins that were identified in the Cercospora nicotianae subtractive library as potential resistance factors. Quantitative RT-PCR analysis of the 20 genes encoding hypothetical proteins showed that two, 24cF and 71cR, were induced under conditions of cercosporin toxicity, suggesting a role in resistance. Transformation and expression of 24cF and 71cR in the cercosporin-sensitive fungus, Neurospora crassa, showed that 71cR provided increased resistance to cercosporin toxicity, whereas no significant increase was observed in 24cF transformants. Gene disruption was used to generate C. nicotianae 71cR mutants; these mutants did not differ from wt C. nicotianae in cercosporin resistance or production. Quantitative RT-PCR analysis showed induction of other resistance genes in the 71cR mutant that may compensate for the loss of 71cR. Analysis of 71cR conserved domains and secondary and tertiary structure identify the protein as having an NTF2-like superfamily DUF1348 domain with unknown function, to be intracellular and localized in the cytosol, and to have similarities to proteins in the steroid delta

  19. Characterization of Cercospora nicotianae Hypothetical Proteins in Cercosporin Resistance.

    PubMed

    Beseli, Aydin; Noar, Roslyn; Daub, Margaret E

    2015-01-01

    The photoactivated toxin, cercosporin, produced by Cercospora species, plays an important role in pathogenesis of this fungus to host plants. Cercosporin has almost universal toxicity to cells due to its production of reactive oxygen species including singlet oxygen. For that reason, Cercospora species, which are highly resistant to their own toxin, are good candidates to identify genes for resistance to cercosporin and to the reactive oxygen species it produces. In previous research, the zinc cluster transcription factor CRG1 (cercosporin resistance gene 1) was found to be crucial for Cercospora species' resistance against cercosporin, and subtractive hybridization analysis identified 185 genes differentially expressed between Cercospora nicotianae wild type (wt) and a crg1 mutant. The focus of this work was to identify and characterize the hypothetical proteins that were identified in the Cercospora nicotianae subtractive library as potential resistance factors. Quantitative RT-PCR analysis of the 20 genes encoding hypothetical proteins showed that two, 24cF and 71cR, were induced under conditions of cercosporin toxicity, suggesting a role in resistance. Transformation and expression of 24cF and 71cR in the cercosporin-sensitive fungus, Neurospora crassa, showed that 71cR provided increased resistance to cercosporin toxicity, whereas no significant increase was observed in 24cF transformants. Gene disruption was used to generate C. nicotianae 71cR mutants; these mutants did not differ from wt C. nicotianae in cercosporin resistance or production. Quantitative RT-PCR analysis showed induction of other resistance genes in the 71cR mutant that may compensate for the loss of 71cR. Analysis of 71cR conserved domains and secondary and tertiary structure identify the protein as having an NTF2-like superfamily DUF1348 domain with unknown function, to be intracellular and localized in the cytosol, and to have similarities to proteins in the steroid delta-isomerase family.

  20. Plant RNA silencing in viral defence.

    PubMed

    Pantaleo, Vitantonio

    2011-01-01

    RNA silencing is described in plants and insects as a defence mechanism against foreign nucleic acids, such as invading viruses. The RNA silencing-based antiviral defence involves the production of virus-derived small interfering RNAs and their association to effector proteins, which together drive the sequence specific inactivation of viruses. The entire process of antiviral defence 'borrows' several plant factors involved in other specialized RNA silencing endogenous pathways. Different viruses use variable strategies to infect different host plants, which render the antiviral RNA silencing a complex phenomenon far to be completely clarified. This chapter reports current advances in understanding the main steps of the plant's RNA-silencing response to viral invasion and discusses some of the key questions still to be answered.

  1. Overexpression of the synthetic chimeric native-T-phylloplanin-GFP genes optimized for monocot and dicot plants renders enhanced resistance to blue mold disease in tobacco (N. tabacum L.).

    PubMed

    Sahoo, Dipak K; Raha, Sumita; Hall, James T; Maiti, Indu B

    2014-01-01

    To enhance the natural plant resistance and to evaluate the antimicrobial properties of phylloplanin against blue mold, we have expressed a synthetic chimeric native-phylloplanin-GFP protein fusion in transgenic Nicotiana tabacum cv. KY14, a cultivar that is highly susceptible to infection by Peronospora tabacina. The coding sequence of the tobacco phylloplanin gene along with its native signal peptide was fused with GFP at the carboxy terminus. The synthetic chimeric gene (native-phylloplanin-GFP) was placed between the modified Mirabilis mosaic virus full-length transcript promoter with duplicated enhancer domains and the terminator sequence from the rbcSE9 gene. The chimeric gene, expressed in transgenic tobacco, was stably inherited in successive plant generations as shown by molecular characterization, GFP quantification, and confocal fluorescent microscopy. Transgenic plants were morphologically similar to wild-type plants and showed no deleterious effects due to transgene expression. Blue mold-sensitivity assays of tobacco lines were performed by applying P. tabacina sporangia to the upper leaf surface. Transgenic lines expressing the fused synthetic native-phyllopanin-GFP gene in the leaf apoplast showed resistance to infection. Our results demonstrate that in vivo expression of a synthetic fused native-phylloplanin-GFP gene in plants can potentially achieve natural protection against microbial plant pathogens, including P. tabacina in tobacco.

  2. Prophage-mediated defence against viral attack and viral counter-defence.

    PubMed

    Dedrick, Rebekah M; Jacobs-Sera, Deborah; Bustamante, Carlos A Guerrero; Garlena, Rebecca A; Mavrich, Travis N; Pope, Welkin H; Reyes, Juan C Cervantes; Russell, Daniel A; Adair, Tamarah; Alvey, Richard; Bonilla, J Alfred; Bricker, Jerald S; Brown, Bryony R; Byrnes, Deanna; Cresawn, Steven G; Davis, William B; Dickson, Leon A; Edgington, Nicholas P; Findley, Ann M; Golebiewska, Urszula; Grose, Julianne H; Hayes, Cory F; Hughes, Lee E; Hutchison, Keith W; Isern, Sharon; Johnson, Allison A; Kenna, Margaret A; Klyczek, Karen K; Mageeney, Catherine M; Michael, Scott F; Molloy, Sally D; Montgomery, Matthew T; Neitzel, James; Page, Shallee T; Pizzorno, Marie C; Poxleitner, Marianne K; Rinehart, Claire A; Robinson, Courtney J; Rubin, Michael R; Teyim, Joseph N; Vazquez, Edwin; Ware, Vassie C; Washington, Jacqueline; Hatfull, Graham F

    2017-01-09

    Temperate phages are common, and prophages are abundant residents of sequenced bacterial genomes. Mycobacteriophages are viruses that infect mycobacterial hosts including Mycobacterium tuberculosis and Mycobacterium smegmatis, encompass substantial genetic diversity and are commonly temperate. Characterization of ten Cluster N temperate mycobacteriophages revealed at least five distinct prophage-expressed viral defence systems that interfere with the infection of lytic and temperate phages that are either closely related (homotypic defence) or unrelated (heterotypic defence) to the prophage. Target specificity is unpredictable, ranging from a single target phage to one-third of those tested. The defence systems include a single-subunit restriction system, a heterotypic exclusion system and a predicted (p)ppGpp synthetase, which blocks lytic phage growth, promotes bacterial survival and enables efficient lysogeny. The predicted (p)ppGpp synthetase coded by the Phrann prophage defends against phage Tweety infection, but Tweety codes for a tetrapeptide repeat protein, gp54, which acts as a highly effective counter-defence system. Prophage-mediated viral defence offers an efficient mechanism for bacterial success in host-virus dynamics, and counter-defence promotes phage co-evolution.

  3. Plant surface reactions: an opportunistic ozone defence mechanism impacting atmospheric chemistry

    NASA Astrophysics Data System (ADS)

    Jud, W.; Fischer, L.; Canaval, E.; Wohlfahrt, G.; Tissier, A.; Hansel, A.

    2016-01-01

    Elevated tropospheric ozone concentrations are considered a toxic threat to plants, responsible for global crop losses with associated economic costs of several billion dollars per year. Plant injuries have been linked to the uptake of ozone through stomatal pores and oxidative damage of the internal leaf tissue. But a striking question remains: can surface reactions limit the stomatal uptake of ozone and therefore reduce its detrimental effects to plants?In this laboratory study we could show that semi-volatile organic compounds exuded by the glandular trichomes of different Nicotiana tabacum varieties are an efficient ozone sink at the plant surface. In our experiments, different diterpenoid compounds were responsible for a strongly variety-dependent ozone uptake of plants under dark conditions, when stomatal pores are almost closed. Surface reactions of ozone were accompanied by a prompt release of oxygenated volatile organic compounds, which could be linked to the corresponding precursor compounds: ozonolysis cis-abienol (C20H34O) - a diterpenoid with two exocyclic double bonds - caused emissions of formaldehyde (HCHO) and methyl vinyl ketone (C4H6O). The ring-structured cembratrien-diols (C20H34O2) with three endocyclic double bonds need at least two ozonolysis steps to form volatile carbonyls such as 4-oxopentanal (C5H8O2), which we could observe in the gas phase, too.Fluid dynamic calculations were used to model ozone distribution in the diffusion-limited leaf boundary layer under daylight conditions. In the case of an ozone-reactive leaf surface, ozone gradients in the vicinity of stomatal pores are changed in such a way that the ozone flux through the open stomata is strongly reduced.Our results show that unsaturated semi-volatile compounds at the plant surface should be considered as a source of oxygenated volatile organic compounds, impacting gas phase chemistry, as well as efficient ozone sink improving the ozone tolerance of plants.

  4. Towards an internet civil defence against bioterrorism.

    PubMed

    LaPorte, R E; Sauer, F; Dearwater, S; Sekikawa, A; Sa, E R; Aaron, D; Shubnikov, E

    2001-09-01

    Approaches towards the public-health prevention of bioterrorism are too little, and too late. New information-based approaches could yield better homeland protection. An internet civil defence is presented where millions of eyes could help to identify suspected cases of bioterrorism, with the internet used to report, confirm, and prevent outbreaks.

  5. In Defence of the Classroom Science Demonstration

    ERIC Educational Resources Information Center

    McCrory, Paul

    2013-01-01

    Science demonstrations are often criticised for their passive nature, their gratuitous exploitation and their limited ability to develop scientific knowledge and understanding. This article is intended to present a robust defence of the use of demonstrations in the classroom by identifying some of their unique and powerful benefits--practical,…

  6. Malaysian Defence and E-Learning

    ERIC Educational Resources Information Center

    Juhary, Jowati binti

    2005-01-01

    This paper begins with an analysis of the changing security scenario in the Asian region, with special focus on Malaysian defence strategies and foreign policies. Beginning in the mid 1990s, the Malaysian government shifted its attention away from the counter insurgency strategies of the early decades of independence to focus on wider questions of…

  7. Superconductivity: Recent Developments and Defence Applications

    DTIC Science & Technology

    1988-03-11

    particular interest to the defence community include: batteries , bearings, electromagnetic guns and launchers, energy storage, free electron lasers...has looked at muon spin rotation measurements of the penetration depth of magnetic fields into the superconductors. Basic research is under way at Chalk...and batteries (3) High density magnetic field transducers (4) Magnetic levitation (5) Magnetic, frictionless be arings (6) Magnetic separation (7

  8. Swedish Defence Acquisition Transformation: A Research Agenda

    DTIC Science & Technology

    2015-05-13

    presentation • A small country perspective • The swinging pendulum : “From preparedness to deployment to preparedness?” – or “from national defence to PSOs to...history of war The swinging (political) pendulum • A. 200 years of peace – Standing in preparedness • B. Post Cold War – Deployed on PSOs • C

  9. Testing the optimal defence hypothesis for two indirect defences: extrafloral nectar and volatile organic compounds

    PubMed Central

    Radhika, Venkatesan; Kost, Christian; Bartram, Stefan; Heil, Martin

    2008-01-01

    Many plants respond to herbivory with an increased production of extrafloral nectar (EFN) and/or volatile organic compounds (VOCs) to attract predatory arthropods as an indirect defensive strategy. In this study, we tested whether these two indirect defences fit the optimal defence hypothesis (ODH), which predicts the within-plant allocation of anti-herbivore defences according to trade-offs between growth and defence. Using jasmonic acid-induced plants of Phaseolus lunatus and Ricinus communis, we tested whether the within-plant distribution pattern of these two indirect defences reflects the fitness value of the respective plant parts. Furthermore, we quantified photosynthetic rates and followed the within-plant transport of assimilates with 13C labelling experiments. EFN secretion and VOC emission were highest in younger leaves. Moreover, the photosynthetic rate increased with leaf age, and pulse-labelling experiments suggested transport of carbon to younger leaves. Our results demonstrate that the ODH can explain the within-plant allocation pattern of both indirect defences studied. PMID:18493790

  10. Rusi/Brassey's defence yearbook 1987 97th edition

    SciTech Connect

    Not Available

    1987-01-01

    This annual review of defence and strategic affairs provides an up-to-date survey of international strategic affairs, contemporary weapons and developments and future trends. For all those involved in defence studies, university and public libraries and the general public. Contents: The Year Ahead; The Middle East; NATO; The Soviet Union and Eastern Europe; UK defence policy; The Issues: What is SDI.; Will SDI help. A military view; SDI-the industrial implications; Conventional defence, a military view; An alternative view; European armaments cooperation; Terrorism; Sri Lanka: the Tamils; Israel 1986; The Iran/Iraq war; Arab view; South Africa; Chronology of conflict; Defence literature; Arms control; Nuclear weapons; Characteristics.

  11. [Turkish (Aztec) tobbaco (Nicotiana rustica L.) unnoticeable danger?].

    PubMed

    Modnicki, Daniel

    2007-01-01

    Tobacco harmful influence on men's health is usually linked with smoking cigarettes. Alternative ways of intake tobacco are also dangerous. Nicotine and tobacco-specific N-nitrosamines with carcinogenic activity are not only present in tobacco smoke but also of nicotine-rich product for chewing. There are some internet sources about Turkish (Aztec) tobacco (Nicotiana rustica L.) as easy available material for home-made tobacco mixtures. A some reports about dangerous effects connected with chewing tobacco and similar to smoking-related disorders are present in current literature.

  12. Genetic analysis of Phytophthora nicotianae populations from different hosts using microsatellite markers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two hundred thirty-one isolates of P. nicotianae representing 14 populations from different host genera, including agricultural crops (Citrus, Nicotiana, and Lycopersicon), potted ornamental species in nurseries (Lavandula, Convolvulus, Myrtus, Correa and Ruta) and other plant genera of lesser econo...

  13. Large-scale detection and application of expressed sequence tag single nucleotide polymorphisms in Nicotiana.

    PubMed

    Wang, Y; Zhou, D; Wang, S; Yang, L

    2015-07-14

    Single nucleotide polymorphisms (SNPs) are widespread in the Nicotiana genome. Using an alignment and variation detection method, we developed 20,607,973 SNPs, based on the expressed sequence tag sequences of 10 Nicotiana species. The replacement rate was much higher than the transversion rate in the SNPs, and SNPs widely exist in the Nicotiana. In vitro verification indicated that all of the SNPs were high quality and accurate. Evolutionary relationships between 15 varieties were investigated by polymerase chain reaction with a special primer; the specific 302 locus of these sequence results clearly indicated the origin of Zhongyan 100. A database of Nicotiana SNPs (NSNP) was developed to store and search for SNPs in Nicotiana. NSNP is a tool for researchers to develop SNP markers of sequence data.

  14. Trade-offs between constitutive and induced defences drive geographical and climatic clines in pine chemical defences.

    PubMed

    Moreira, Xoaquín; Mooney, Kailen A; Rasmann, Sergio; Petry, William K; Carrillo-Gavilán, Amparo; Zas, Rafael; Sampedro, Luis

    2014-05-01

    There is increasing evidence that geographic and climatic clines drive the patterns of plant defence allocation and defensive strategies. We quantified early growth rate and both constitutive and inducible chemical defences of 18 Pinaceae species in a common greenhouse environment and assessed their defensive allocation with respect to each species' range across climatic gradients spanning 31° latitude and 2300 m elevation. Constitutive defences traded-off with induced defences, and these defensive strategies were associated with growth rate such that slow-growing species invested more in constitutive defence, whereas fast-growing species invested more in inducible defence. The position of each pine species along this trade-off axis was in turn associated with geography; moving poleward and to higher elevations, growth rate and inducible defences decreased, while constitutive defence increased. These geographic patterns in plant defence were most strongly associated with variation in temperature. Climatic and geographical clines thus act as drivers of defence profiles by mediating the constraints imposed by trade-offs, and this dynamic underlays global patterns of defence allocation.

  15. Peptides as triggers of plant defence.

    PubMed

    Albert, Markus

    2013-12-01

    Plants are confronted with several biotic stresses such as microbial pathogens and other herbivores. To defend against such attackers, plants possess an array of pattern recognition receptors (PRRs) that sense the danger and consequently initiate a defence programme that prevents further damage and spreading of the pest. Characteristic pathogenic structures, so-called microbe-associated molecular patterns (MAMPs), serve as signals that allow the plant to sense invaders. Additionally, pathogens wound or damage the plant and the resulting release of damage-associated molecular patterns (DAMPs) serves as a warning signal. This review focuses on peptides that serve as triggers or amplifiers of plant defence and thus follow the definition of a MAMP or a DAMP.

  16. Are natural antibodies involved in tumour defence?

    PubMed

    Bohn, J

    1999-09-01

    Natural antibodies (NAb) are found in the serum of healthy individuals. These antibodies are produced without any apparent specific antigenic stimulation. They are one part of the circulating immunoglobulins and are found in virtually all vertebrate species. NAb react to various self- and non-self antigens. A protective function in different infection models could be demonstrated. Several groups have reported the ability of NAb to bind to tumour cells. Their possible role in tumour defence is documented in mice. The present status of attempts to characterise the role of NAb in tumour defence is discussed, particularly as regards the human immune system. This paper focuses on antibody cell interactions and discusses the genetic background of the Nab-producing B-cells.

  17. Doubts about a classic defence of abortion.

    PubMed

    Difford, Jo

    2011-01-01

    Professor Judith Jarvis Thomson's seminal paper "A defence of abortion" published in 1971 has formed part of higher education syllabi for decades. In the paper Thomson criticizes one of the fundamental arguments against abortion, that is, the right of the foetus to life by denying that the foetus is a person. This article argues that her thought experiments do not compare to the reality of abortion and focuses on the influence of the paper on arguments concerning personhood.

  18. The Man-in-the-Middle Defence

    NASA Astrophysics Data System (ADS)

    Anderson, Ross; Bond, Mike

    Eliminating middlemen from security protocols helps less than one would think. EMV electronic payments, for example, can be made fairer by adding an electronic attorney - a middleman which mediates access to a customer’s card. We compare middlemen in crypto protocols and APIs with those in the real world, and show that a man-in-the-middle defence is helpful in many circumstances. We suggest that the middleman has been unfairly demonised.

  19. Jasmonate in plant defence: sentinel or double agent?

    PubMed

    Yan, Chun; Xie, Daoxin

    2015-12-01

    Plants and their biotic enemies, such as microbial pathogens and herbivorous insects, are engaged in a desperate battle which would determine their survival-death fate. Plants have evolved efficient and sophisticated systems to defend against such attackers. In recent years, significant progress has been made towards a comprehensive understanding of inducible defence system mediated by jasmonate (JA), a vital plant hormone essential for plant defence responses and developmental processes. This review presents an overview of JA action in plant defences and discusses how microbial pathogens evade plant defence system through hijacking the JA pathway.

  20. Acute respiratory failure due to Nicotiana glauca ingestion

    PubMed Central

    Ntelios, D; Kargakis, M; Topalis, T; Drouzas, A; Potolidis, E

    2013-01-01

    Background: A variety of organisms produce potent toxins that impact human health through compromising respiratory function. Case report: We describe a rare case of abrupt respiratory failure afterNicotiana glaucaingestion in a previously healthy sixty years old female patient. She presented complaining for gait instability and malaise after ingestion of cooked leaves of the wild plant and two hours after the onset she developed respiratory failurefor which she was intubated and mechanically ventilated for two days. The patient fully recovered and was discharged from the hospital. Conclusion: Anabasine, the plant’s main active ingredient, can cause severe systemic intoxication due to its nicotinic receptor agonist action with respiratory muscle paralysis being the main effect. PMID:24376330

  1. Iron homeostasis in host defence and inflammation

    PubMed Central

    Ganz, Tomas; Nemeth, Elizabeta

    2016-01-01

    Iron is an essential trace element for multicellular organisms and nearly all microorganisms. Although iron is abundant in the environment, common forms of iron are minimally soluble and therefore poorly accessible to biological organisms. Microorganisms entering a mammalian host face multiple mechanisms that further restrict their ability to obtain iron and thereby limit their pathogenicity. Iron levels also modulate host defence, as iron content in macrophages regulates their cytokine production. Here, we review recent advances that highlight the role of systemic and cellular iron-regulating mechanisms in protecting hosts from infection, emphasizing aspects that are applicable to human health and disease. PMID:26160612

  2. Clostridium difficile colitis: pathogenesis and host defence.

    PubMed

    Abt, Michael C; McKenney, Peter T; Pamer, Eric G

    2016-10-01

    Clostridium difficile is a major cause of intestinal infection and diarrhoea in individuals following antibiotic treatment. Recent studies have begun to elucidate the mechanisms that induce spore formation and germination and have determined the roles of C. difficile toxins in disease pathogenesis. Exciting progress has also been made in defining the role of the microbiome, specific commensal bacterial species and host immunity in defence against infection with C. difficile. This Review will summarize the recent discoveries and developments in our understanding of C. difficile infection and pathogenesis.

  3. In Defence of Multimodal Re-Signification: A Response to Havard Skaar's "In Defence of Writing"

    ERIC Educational Resources Information Center

    Adami, Elisabetta

    2011-01-01

    Responding to "In defence of writing" by Havard Skaar, published in issue 43.1 of this journal (April 2009), the present article argues that (1) compared with text production "from scratch," producing texts through copy-and-paste requires a different type of--rather than less--semiotic work, and that (2) digitally produced writing may involve the…

  4. Cotton GhMKK5 affects disease resistance, induces HR-like cell death, and reduces the tolerance to salt and drought stress in transgenic Nicotiana benthamiana

    PubMed Central

    Zhang, Liang; Li, Yuzhen; Lu, Wenjing; Meng, Fei; Wu, Chang-ai; Guo, Xingqi

    2012-01-01

    Mitogen-activated protein kinase (MAPK) cascades are involved in various processes from plant growth and development to biotic and abiotic stress responses. MAPK kinases (MAPKKs), which link MAPKs and MAPKK kinases (MAPKKKs), play crucial roles in MAPK cascades to mediate a variety of stress responses in plants. However, few MAPKKs have been functionally characterized in cotton (Gossypium hirsutum). In this study, a novel gene, GhMKK5, from cotton belonging to the group C MAPKKs was isolated and characterized. The expression of GhMKK5 can be induced by pathogen infection, abiotic stresses, and multiple defence-related signal molecules. The overexpression of GhMKK5 in Nicotiana benthamiana enhanced the plants’ resistance to the bacterial pathogen Ralstonia solanacearum by elevating the expression of pathogen resistance (PR) genes, including PR1a, PR2, PR4, PR5, and NPR1, but increased the plants’ sensitivity to the oomycete pathogen Phytophthora parasitica var. nicotianae Tucker. Importantly, GhMKK5-overexpressing plants displayed markedly elevated expression of reactive oxygen species-related and cell death marker genes, such as NtRbohA and NtCDM, and resulted in hypersensitive response (HR)-like cell death characterized by the accumulation of H2O2. Furthermore, it was demonstrated that GhMKK5 overexpression in plants reduced their tolerance to salt and drought stresses, as determined by statistical analysis of seed germination, root length, leaf water loss, and survival rate. Drought obviously accelerated the cell death phenomenon in GhMKK5-overexpressing plants. These results suggest that GhMKK5 may play an important role in pathogen infection and the regulation of the salt and drought stress responses in plants. PMID:22442420

  5. Cell physiology of mortality and immortality in a Nicotiana interspecific F1 hybrid complies with the quantitative balance between reactive oxygen and nitric oxide.

    PubMed

    Yamamoto, Takumi; Shomura, Sachiko; Mino, Masanobu

    2017-03-01

    The cultured cell line, GTH4, of an interspecific F1 hybrid between Nicotiana gossei Domin and N. tabacum L. died after a shift in temperature from 37°C to 26°C. Fluctuations in the cellular amounts of reactive oxygen species (ROS) and nitric oxide (NO) were detected in GTH4 after the temperature shift, but not in the mutant, GTH4S, which did not die at 26°C presumably due to the lack of genetic factors involved in cell death. The removal of ROS or NO suppressed cell death in GTH4, suggesting that ROS and NO both acted as mediators of cell death. However, excess amounts of the superoxide anion (O2(-)) or NO alleviated cell death. A series of experiments using generators and scavengers of ROS and NO showed that O2(-) affected the cellular levels of NO, and vice versa, indicating that a quantitative balance between O2(-) and NO was important for hybrid cell death. The combination of NO and hydrogen peroxide (H2O2) was necessary and sufficient to initiate cell death in GTH4 and GTH4S. Hypoxia, which suppressed cell death in GTH4 at 26°C, reduced the generation of H2O2 and NO, but allowed for the production of O2(-), which acted as a suppressor and/or modulator of cell death. The activation of MAPK was involved in the generation of H2O2 in GTG4 cells under normoxic conditions, but promoted O2(-) generation under hypoxic conditions. More protective cellular conditions against ROS, as estimated by the expression levels of genes for ROS-scavenging enzymes, may be involved in the mechanisms responsible for the low cell death rate of GTH4 under hypoxic conditions.

  6. Some Methods for Scenario Analysis in Defence Strategic Planning

    DTIC Science & Technology

    Scenarios are an important tool in the strategic planning process, and are increasingly used in both the Defence and business world. This paper...illustrated with small examples. We also demonstrate a single, flexible approach to combining these methods using a typical Defence strategic planning problem

  7. Resolving defence mechanisms: A perspective based on dissipative structure theory.

    PubMed

    Zhang, Wei; Guo, Ben-Yu

    2017-04-01

    Theories and classifications of defence mechanisms are not unified. This study addresses the psychological system as a dissipative structure which exchanges information with the external and internal world. When using defence mechanisms, the cognitive-affective schema of an individual could remain stable and ordered by excluding psychological entropy, obtaining psychological negentropy or by dissipating the energy of self-presentation. From this perspective, defences can be classified into three basic types: isolation, compensation and self-dissipation. However, not every kind of defence mechanisms can actually help the individual. Non-adaptive defences are just functioning as an effective strategy in the short run but can be a harmful approach in the long run, while adaptive defences could instead help the individual as a long-term mechanism. Thus, we would like to suggest that it is more useful for the individual to use more adaptive defence mechanisms and seek out social or interpersonal support when undergoing psychic difficulties. As this model of defences is theoretical at present, we therefore aim to support and enrich this viewpoint with empirical evidence.

  8. Comparative analysis of passive defences in spiders (Araneae).

    PubMed

    Pekár, Stano

    2014-07-01

    Being frequent prey of many predators, including especially wasps and birds, spiders have evolved a variety of defence mechanisms. Here I studied patterns of passive defences, namely anachoresis, crypsis, masquerade, aposematism and Batesian mimicry, in spiders. Using published information pertaining more than 1000 spider species, the phylogenetic pattern of different passive defences (i.e. defences that decrease the risk of an encounter with the predator) was investigated. Furthermore, I studied the effect of foraging guild, geographical distribution and diel activity on the frequency of defences as these determine the predators diversity, presence and perception. I found that crypsis (background matching) combined with anachoresis (hiding) was the most frequent defence confined mainly to families/genera at the base of the tree. Aposematism (warning coloration) and Batesian mimicry (imitation of noxious/dangerous model) were found in taxa that branched later in the tree, and masquerade (imitation of inedible objects) was confined to families at intermediate positions of the tree. Aposematism and Batesian mimicry were restricted to a few lineages. Masquerade was used particularly by web-building species with nocturnal activity. Aposematism was rare but mainly used by web-building diurnal species. Batesian mimicry was frequently observed in cursorial species with diurnal activity. Cryptic species were more common in temperate zones, whereas aposematic and mimetic species were more common in the tropics. Here I show that the evolution of passive defences in spiders was influenced by the ecology of species. Then, I discuss the evolutionary significance of the particularly defences.

  9. Costs of Inducible Defence along a Resource Gradient

    PubMed Central

    Brönmark, Christer; Lakowitz, Thomas; Nilsson, P. Anders; Ahlgren, Johan; Lennartsdotter, Charlotte; Hollander, Johan

    2012-01-01

    In addition to having constitutive defence traits, many organisms also respond to predation by phenotypic plasticity. In order for plasticity to be adaptive, induced defences should incur a benefit to the organism in, for example, decreased risk of predation. However, the production of defence traits may include costs in fitness components such as growth, time to reproduction, or fecundity. To test the hypothesis that the expression of phenotypic plasticity incurs costs, we performed a common garden experiment with a freshwater snail, Radix balthica, a species known to change morphology in the presence of molluscivorous fish. We measured a number of predator-induced morphological and behavioural defence traits in snails that we reared in the presence or absence of chemical cues from fish. Further, we quantified the costs of plasticity in fitness characters related to fecundity and growth. Since plastic responses may be inhibited under limited resource conditions, we reared snails in different densities and thereby levels of competition. Snails exposed to predator cues grew rounder and thicker shells, traits confirmed to be adaptive in environments with fish. Defence traits were consistently expressed independent of density, suggesting strong selection from predatory molluscivorous fish. However, the expression of defence traits resulted in reduced growth rate and fecundity, particularly with limited resources. Our results suggest full defence in predator related traits regardless of resource availability, and costs of defence consequently paid in traits related to fitness. PMID:22291961

  10. Computed Tomography Technology: Development and Applications for Defence

    SciTech Connect

    Baheti, G. L.; Saxena, Nisheet; Tripathi, D. K.; Songara, K. C.; Meghwal, L. R.; Meena, V. L.

    2008-09-26

    Computed Tomography(CT) has revolutionized the field of Non-Destructive Testing and Evaluation (NDT and E). Tomography for industrial applications warrants design and development of customized solutions catering to specific visualization requirements. Present paper highlights Tomography Technology Solutions implemented at Defence Laboratory, Jodhpur (DLJ). Details on the technological developments carried out and their utilization for various Defence applications has been covered.

  11. Costs of inducible defence along a resource gradient.

    PubMed

    Brönmark, Christer; Lakowitz, Thomas; Nilsson, P Anders; Ahlgren, Johan; Lennartsdotter, Charlotte; Hollander, Johan

    2012-01-01

    In addition to having constitutive defence traits, many organisms also respond to predation by phenotypic plasticity. In order for plasticity to be adaptive, induced defences should incur a benefit to the organism in, for example, decreased risk of predation. However, the production of defence traits may include costs in fitness components such as growth, time to reproduction, or fecundity. To test the hypothesis that the expression of phenotypic plasticity incurs costs, we performed a common garden experiment with a freshwater snail, Radix balthica, a species known to change morphology in the presence of molluscivorous fish. We measured a number of predator-induced morphological and behavioural defence traits in snails that we reared in the presence or absence of chemical cues from fish. Further, we quantified the costs of plasticity in fitness characters related to fecundity and growth. Since plastic responses may be inhibited under limited resource conditions, we reared snails in different densities and thereby levels of competition. Snails exposed to predator cues grew rounder and thicker shells, traits confirmed to be adaptive in environments with fish. Defence traits were consistently expressed independent of density, suggesting strong selection from predatory molluscivorous fish. However, the expression of defence traits resulted in reduced growth rate and fecundity, particularly with limited resources. Our results suggest full defence in predator related traits regardless of resource availability, and costs of defence consequently paid in traits related to fitness.

  12. Computed Tomography Technology: Development and Applications for Defence

    NASA Astrophysics Data System (ADS)

    Baheti, G. L.; Saxena, Nisheet; Tripathi, D. K.; Songara, K. C.; Meghwal, L. R.; Meena, V. L.

    2008-09-01

    Computed Tomography(CT) has revolutionized the field of Non-Destructive Testing and Evaluation (NDT&E). Tomography for industrial applications warrants design and development of customized solutions catering to specific visualization requirements. Present paper highlights Tomography Technology Solutions implemented at Defence Laboratory, Jodhpur (DLJ). Details on the technological developments carried out and their utilization for various Defence applications has been covered.

  13. Pakistan’s Economic and Security Dilemma: Expanded Defence Expenditures and the Relative Governance Syndrome

    DTIC Science & Technology

    2008-03-01

    higher governance countries, defence expenditures can have a positive impact on economic growth (Table 7). Table 6. Anticipated defence spending in high...predicted expenditures , conditional on governance structures. Low defence spending countries can obtain positive benefits from defence by cutting back...that obtains no positive benefit from their low level of defence. On the other hand, if low defence spending countries can cut back their expenditures

  14. Ecological mechanisms for the coevolution of mating systems and defence.

    PubMed

    Campbell, Stuart A

    2015-02-01

    The diversity of flowering plants is evident in two seemingly unrelated aspects of life history: sexual reproduction, exemplified by the stunning variation in flower form and function, and defence, often in the form of an impressive arsenal of secondary chemistry. Researchers are beginning to appreciate that plant defence and reproduction do not evolve independently, but, instead, may have reciprocal and interactive (coevolutionary) effects on each other. Understanding the mechanisms for mating-defence interactions promises to broaden our understanding of how ecological processes can generate these two rich sources of angiosperm diversity. Here, I review current research on the role of herbivory as a driver of mating system evolution, and the role of mating systems in the evolution of defence strategies. I outline different ecological mechanisms and processes that could generate these coevolutionary patterns, and summarize theoretical and empirical support for each. I provide a conceptual framework for linking plant defence with mating system theory to better integrate these two research fields.

  15. A saponin-detoxifying enzyme mediates suppression of plant defences

    NASA Astrophysics Data System (ADS)

    Bouarab, K.; Melton, R.; Peart, J.; Baulcombe, D.; Osbourn, A.

    2002-08-01

    Plant disease resistance can be conferred by constitutive features such as structural barriers or preformed antimicrobial secondary metabolites. Additional defence mechanisms are activated in response to pathogen attack and include localized cell death (the hypersensitive response). Pathogens use different strategies to counter constitutive and induced plant defences, including degradation of preformed antimicrobial compounds and the production of molecules that suppress induced plant defences. Here we present evidence for a two-component process in which a fungal pathogen subverts the preformed antimicrobial compounds of its host and uses them to interfere with induced defence responses. Antimicrobial saponins are first hydrolysed by a fungal saponin-detoxifying enzyme. The degradation product of this hydrolysis then suppresses induced defence responses by interfering with fundamental signal transduction processes leading to disease resistance.

  16. Asymmetric selection and the evolution of extraordinary defences.

    PubMed

    Urban, Mark C; Bürger, Reinhard; Bolnick, Daniel I

    2013-01-01

    Evolutionary biologists typically predict future evolutionary responses to natural selection by analysing evolution on an adaptive landscape. Much theory assumes symmetric fitness surfaces even though many stabilizing selection gradients deviate from symmetry. Here we revisit Lande's adaptive landscape and introduce novel analytical theory that includes asymmetric selection. Asymmetric selection and the resulting skewed trait distributions bias equilibrium mean phenotypes away from fitness peaks, usually toward the flatter shoulder of the individual fitness surface. We apply this theory to explain a longstanding paradox in biology and medicine: the evolution of excessive defences against enemies. These so-called extraordinary defences can evolve in response to asymmetrical selection when marginal risks of insufficient defence exceed marginal costs of excessive defence. Eco-evolutionary feedbacks between population abundances and asymmetric selection further exaggerate these defences. Recognizing the effect of asymmetrical selection on evolutionary trajectories will improve the accuracy of predictions and suggest novel explanations for apparent sub-optimality.

  17. Decreased structural defence of an invasive thistle under warming.

    PubMed

    Zhang, R; Leshak, A; Shea, K

    2012-01-01

    Plant structural defences play a key role in preventing fitness loss due to herbivory. However, how structural defences are affected by potential climate change is rarely examined. We examined how leaf morphological traits that relate to the structural defence of an invasive thistle, Carduus nutans, change in a warmer climate. We manipulated warming using open-top chambers (OTCs) and examined the morphology of leaves at three different positions (the 5th, 10th and 15th leaves, counted from the top of the plant) in two destructive summer censuses. We found that structural defence traits were different under ambient versus warmed conditions. Prickle densities (both the number of prickles per leaf area and the number of prickles per leaf mass) were significantly lower in plants grown in a warmer climate. Our results suggest that plant structural defences may be reduced under warming, and therefore should be considered when examining species' responses to climate change.

  18. Tomato Pto encodes a functional N-myristoylation motif that is required for signal transduction in Nicotiana benthamiana.

    PubMed

    de Vries, Jeroen S; Andriotis, Vasilios M E; Wu, Ai-Jiuan; Rathjen, John P

    2006-01-01

    Pto kinase of tomato (Lycopersicon esculentum) confers resistance to bacterial speck disease caused by Pseudomonas syringae pv. tomato expressing avrPto or avrPtoB. Pto interacts directly with these type-III secreted effectors, leading to induction of defence responses including the hypersensitive response (HR). Signalling by Pto requires the nucleotide-binding site-leucine-rich repeat (NBS-LRR) protein Prf. Little is known of how Pto is controlled prior to or during stimulation, although kinase activity is required for Avr-dependent activation. Here we demonstrate a role for the N-terminus in signalling by Pto. N-terminal residues outside the kinase domain were required for induction of the HR in Nicotiana benthamiana. The N-terminus also contributed to both AvrPto-binding and phosphorylation abilities. Pto residues 1-10 comprise a consensus motif for covalent attachment of myristate, a hydrophobic 14-carbon saturated fatty acid, to the Gly-2 residue. Several lines of evidence indicate that this motif is important for Pto function. A heterologous N-myristoylation motif complemented N-terminal deletion mutants of Pto for Prf-dependent signalling. Signalling by wild-type and mutant forms of Pto was strictly dependent on the Gly-2 residue. The N-myristoylation motif of Pto complemented the cognate motif of AvrPto for avirulence function and membrane association. Furthermore, Pto was myristoylated in vivo dependent on the presence of Gly-2. The subcellular localization of Pto was independent of N-myristoylation, indicating that N-myristoylation is required for some function other than membrane affinity. Consistent with this idea, AvrPtoB was also found to be a soluble protein. The data indicate an important role(s) for the myristoylated N-terminus in Pto signalling.

  19. The Transformation from Defence Procurement to Defence Acquisition - Opportunities for New Forms of Analytical Support

    DTIC Science & Technology

    2010-04-01

    to the Nordic Battle Group, NBG. Also, the defence industry in Sweden was domestic during the Cold War Era. With the current globalisation and...voyage to the AOR, or, more specifically, to the Reception Staging and Onwards Movement (RSOM) area. A tactical transport will then transport units...Rules Of Engagement RSOM: Reception Staging and Onwards Movement SAC: Strategic Airlift Capability SALIS: Strategic Airlift Interim Solution SCC

  20. Virus infection suppresses Nicotiana benthamiana adaptive phenotypic plasticity.

    PubMed

    Bedhomme, Stéphanie; Elena, Santiago F

    2011-02-17

    Competition and parasitism are two important selective forces that shape life-histories, migration rates and population dynamics. Recently, it has been shown in various pathosystems that parasites can modify intraspecific competition, thus generating an indirect cost of parasitism. Here, we investigated if this phenomenon was present in a plant-potyvirus system using two viruses of different virulence (Tobacco etch virus and Turnip mosaic virus). Moreover, we asked if parasitism interacted with the shade avoidance syndrome, the plant-specific phenotypic plasticity in response to intraspecific competition. Our results indicate that the modification of intraspecific competition by parasitism is not present in the Nicotiana benthamiana--potyvirus system and suggests that this phenomenon is not universal but depends on the peculiarities of each pathosystem. However, whereas the healthy N. benthamiana presented a clear shade avoidance syndrome, this phenotypic plasticity totally disappeared when the plants were infected with TEV and TuMV, very likely resulting in a fitness loss and being another form of indirect cost of parasitism. This result suggests that the suppression or the alteration of adaptive phenotypic plasticity might be a component of virulence that is often overlooked.

  1. Virus Infection Suppresses Nicotiana benthamiana Adaptive Phenotypic Plasticity

    PubMed Central

    Bedhomme, Stéphanie; Elena, Santiago F.

    2011-01-01

    Competition and parasitism are two important selective forces that shape life-histories, migration rates and population dynamics. Recently, it has been shown in various pathosystems that parasites can modify intraspecific competition, thus generating an indirect cost of parasitism. Here, we investigated if this phenomenon was present in a plant-potyvirus system using two viruses of different virulence (Tobacco etch virus and Turnip mosaic virus). Moreover, we asked if parasitism interacted with the shade avoidance syndrome, the plant-specific phenotypic plasticity in response to intraspecific competition. Our results indicate that the modification of intraspecific competition by parasitism is not present in the Nicotiana benthamiana – potyvirus system and suggests that this phenomenon is not universal but depends on the peculiarities of each pathosystem. However, whereas the healthy N. benthamiana presented a clear shade avoidance syndrome, this phenotypic plasticity totally disappeared when the plants were infected with TEV and TuMV, very likely resulting in a fitness loss and being another form of indirect cost of parasitism. This result suggests that the suppression or the alteration of adaptive phenotypic plasticity might be a component of virulence that is often overlooked. PMID:21359142

  2. A tobamovirus expression vector for agroinfection of legumes and Nicotiana.

    PubMed

    Liu, Zun; Kearney, Christopher M

    2010-06-01

    The highest recombinant protein expression levels in plants have been achieved using tobacco mosaic virus (TMV) vectors via agroinoculation of the tobacco, Nicotiana benthamiana. These vectors have been utilized for pharmaceutical protein production and also can serve as rapid gene expression screens for proteonomics. We have constructed a similar vector based on the legume-infecting tobamovirus, sunn hemp mosaic virus (SHMV), by deleting the coat protein gene (SHMV eliminate coat protein gene or SHEC). SHEC/GFP co-agroinoculated with a 35S/p19 binary yielded 600 microg GFP/gfw (25% TSP) in N. benthamiana. In the absence of p19, SHEC/GFP expression was nearly eliminated. SHEC also yielded strong GUS production in agroinoculated Medicago trunculata, Pinto bean, cowpea, pea and lentil even without the aid of systemic infection. A full-length version (SHAC, SHMV alternate coat protein) was created by adding to SHEC the coat protein subgenomic promoter and ORF from the tobamovirus, tobacco mild green mottle virus (TMGMV). SHAC induced a slowly developing, symptomless infection of N. benthamiana and may be of use as a virus induced gene silencing (VIGS) vector.

  3. Specificity in Mesograzer-Induced Defences in Seagrasses

    PubMed Central

    Martínez-Crego, Begoña; Arteaga, Pedro; Ueber, Alexandra; Engelen, Aschwin H.; Santos, Rui; Molis, Markus

    2015-01-01

    Grazing-induced plant defences that reduce palatability to herbivores are widespread in terrestrial plants and seaweeds, but they have not yet been reported in seagrasses. We investigated the ability of two seagrass species to induce defences in response to direct grazing by three associated mesograzers. Specifically, we conducted feeding-assayed induction experiments to examine how mesograzer-specific grazing impact affects seagrass induction of defences within the context of the optimal defence theory. We found that the amphipod Gammarus insensibilis and the isopod Idotea chelipes exerted a low-intensity grazing on older blades of the seagrass Cymodocea nodosa, which reflects a weak grazing impact that may explain the lack of inducible defences. The isopod Synischia hectica exerted the strongest grazing impact on C. nodosa via high-intensity feeding on young blades with a higher fitness value. This isopod grazing induced defences in C. nodosa as indicated by a consistently lower consumption of blades previously grazed for 5, 12 and 16 days. The lower consumption was maintained when offered tissues with no plant structure (agar-reconstituted food), but showing a reduced size of the previous grazing effect. This indicates that structural traits act in combination with chemical traits to reduce seagrass palatability to the isopod. Increase in total phenolics but not in C:N ratio and total nitrogen of grazed C. nodosa suggests chemical defences rather than a modified nutritional quality as primarily induced chemical traits. We detected no induction of defences in Zostera noltei, which showed the ability to replace moderate losses of young biomass to mesograzers via compensatory growth. Our study provides the first experimental evidence of induction of defences against meso-herbivory that reduce further consumption in seagrasses. It also emphasizes the relevance of grazer identity in determining the level of grazing impact triggering resistance and compensatory

  4. The Defence Medical Library Service and military medicine.

    PubMed

    Walker, S B

    2005-01-01

    The Defence Medical Library Service (DMLS) supports the clinical practice and career development of military health professionals across the world. Clinical governance and the need for medical knowledge to be evidence-based means the DMLS has a central role to play in support of defence medicine. The DMLS is important for enabling health professionals to make sense of the evidence-based pyramid and the hierarchy of medical knowledge. The Royal Centre for Defence Medicine (RCDM) in Birmingham is recognised as an international centre of excellence. The information, knowledge and research requirements of the RCDM will provide opportunities for the DMLS to support and engage with the academic community.

  5. Efficacy of Chaetomium Species as Biological Control Agents against Phytophthora nicotianae Root Rot in Citrus.

    PubMed

    Hung, Phung Manh; Wattanachai, Pongnak; Kasem, Soytong; Poeaim, Supattra

    2015-09-01

    Thailand is one of the largest citrus producers in Southeast Asia. Pathogenic infection by Phytophthora, however, has become one of major impediments to production. This study identified a pathogenic oomycete isolated from rotted roots of pomelo (Citrus maxima) in Thailand as Phytophthora nicotianae by the internal transcribed spacer ribosomal DNA sequence analysis. Then, we examined the in vitro and in vivo effects of Chaetomium globosum, Chaetomium lucknowense, Chaetomium cupreum and their crude extracts as biological control agents in controlling this P. nicotianae strain. Represent as antagonists in biculture test, the tested Chaetomium species inhibited mycelial growth by 50~56% and parasitized the hyphae, resulting in degradation of P. nicotianae mycelia after 30 days. The crude extracts of these Chaetomium species exhibited antifungal activities against mycelial growth of P. nicotianae, with effective doses of 2.6~101.4 µg/mL. Under greenhouse conditions, application of spores and methanol extracts of these Chaetomium species to pomelo seedlings inoculated with P. nicotianae reduced root rot by 66~71% and increased plant weight by 72~85% compared to that in the control. The method of application of antagonistic spores to control the disease was simple and economical, and it may thus be applicable for large-scale, highly effective biological control of this pathogen.

  6. Transient Expression of Tetrameric Recombinant Human Butyrylcholinesterase in Nicotiana benthamiana

    PubMed Central

    Alkanaimsh, Salem; Karuppanan, Kalimuthu; Guerrero, Andrés; Tu, Aye M.; Hashimoto, Bryce; Hwang, Min Sook; Phu, My L.; Arzola, Lucas; Lebrilla, Carlito B.; Dandekar, Abhaya M.; Falk, Bryce W.; Nandi, Somen; Rodriguez, Raymond L.; McDonald, Karen A.

    2016-01-01

    To optimize the expression, extraction and purification of plant-derived tetrameric recombinant human butyrylcholinesterase (prBChE), we describe the development and use of plant viral amplicon-based gene expression system; Tobacco Mosaic Virus (TMV) RNA-based overexpression vector (TRBO) to express enzymatically active FLAG-tagged plant made recombinant butyrylcholinesterase (rBChE) in Nicotiana benthamiana leaves using transient agroinfiltration. Two gene expression cassettes were designed to express the recombinant protein in either the ER or to the apoplastic compartment. Leaf homogenization was used to isolate ER-retained recombinant butyrylcholinesterase (prBChE-ER) while apoplast-targeted rBChE was isolated by either leaf homogenization (prBChE) or vacuum-extraction of apoplastic wash fluid (prBChE-AWF). rBChE from apoplast wash fluid had a higher specific activity but lower enzyme yield than leaf homogenate. To optimize the isolation and purification of total recombinant protein from leaf homogenates, an acidic extraction buffer was used. The acidic extraction buffer yielded >95% enzymatically active tetrameric rBChE as verified by Coomassie stained and native gel electrophoresis. Furthermore, when compared to human butyrylcholinesterase, the prBChE was found to be similar in terms of tetramerization and enzyme kinetics. The N-linked glycan profile of purified prBChE-ER was found to be mostly high mannose structures while the N-linked glycans on prBChE-AWF were primarily complex. The glycan profile of the prBChE leaf homogenates showed a mixture of high mannose, complex and paucimannose type N-glycans. These findings demonstrate the ability of plants to produce rBChE that is enzymatically active and whose oligomeric state is comparable to mammalian butyrylcholinesterase. The process of plant made rBChE tetramerization and strategies for improving its pharmacokinetics properties are also discussed. PMID:27379103

  7. Nicotiana benthamiana as a Production Platform for Artemisinin Precursors

    PubMed Central

    van Herpen, Teun W. J. M.; Cankar, Katarina; Nogueira, Marilise; Bosch, Dirk; Bouwmeester, Harro J.; Beekwilder, Jules

    2010-01-01

    Background Production of pharmaceuticals in plants provides an alternative for chemical synthesis, fermentation or natural sources. Nicotiana benthamiana is deployed at commercial scale for production of therapeutic proteins. Here the potential of this plant is explored for rapid production of precursors of artemisinin, a sesquiterpenoid compound that is used for malaria treatment. Methodology/Principal Findings Biosynthetic genes leading to artemisinic acid, a precursor of artemisinin, were combined and expressed in N. benthamiana by agro-infiltration. The first committed precursor of artemisinin, amorpha-4,11-diene, was produced upon infiltration of a construct containing amorpha-4,11-diene synthase, accompanied by 3-hydroxy-3-methylglutaryl-CoA reductase and farnesyl diphosphate synthase. Amorpha-4,11-diene was detected both in extracts and in the headspace of the N. benthamiana leaves. When the amorphadiene oxidase CYP71AV1 was co-infiltrated with the amorphadiene-synthesizing construct, the amorpha-4,11-diene levels strongly decreased, suggesting it was oxidized. Surprisingly, no anticipated oxidation products, such as artemisinic acid, were detected upon GC-MS analysis. However, analysis of leaf extracts with a non-targeted metabolomics approach, using LC-QTOF-MS, revealed the presence of another compound, which was identified as artemisinic acid-12-β-diglucoside. This compound accumulated to 39.5 mg.kg−1 fwt. Apparently the product of the heterologous pathway that was introduced, artemisinic acid, is further metabolized efficiently by glycosyl transferases that are endogenous to N. benthamiana. Conclusion/Significance This work shows that agroinfiltration of N. bentamiana can be used as a model to study the production of sesquiterpenoid pharmaceutical compounds. The interaction between the ectopically introduced pathway and the endogenous metabolism of the plant is discussed. PMID:21151979

  8. Grazing-activated chemical defence in a unicellular marine alga

    NASA Astrophysics Data System (ADS)

    Wolfe, Gordon V.; Steinke, Michael; Kirst, Gunter O.

    1997-06-01

    Marine plankton use a variety of defences against predators, some of which affect trophic structure and biogeochemistry. We have previously shown that, during grazing by the protozoan Oxyrrhis marina on the alga Emiliania huxleyi, dimethylsulphoniopropionate (DMSP) from the prey is converted to dimethyl sulphide (DMS) when lysis of ingested prey cells initiates mixing of algal DMSP and the enzyme DMSP lyase. Such a mechanism is similar to macrophyte defence reactions,. Here we show that this reaction deters protozoan herbivores, presumably through the production of highly concentrated acrylate, which has antimicrobial activity. Protozoan predators differ in their ability to ingest and survive on prey with high-activity DMSP lyase, but all grazers preferentially select strains with low enzyme activity when offered prey mixtures. This defence system involves investment in a chemical precursor, DMSP, which is not self-toxic and has other useful metabolic functions. We believe this is the first report of grazing-activated chemical defence in unicellular microorganisms.

  9. The role of thionins in rice defence against root pathogens.

    PubMed

    Ji, Hongli; Gheysen, Godelieve; Ullah, Chhana; Verbeek, Ruben; Shang, Chenjing; De Vleesschauwer, David; Höfte, Monica; Kyndt, Tina

    2015-10-01

    Thionins are antimicrobial peptides that are involved in plant defence. Here, we present an in-depth analysis of the role of rice thionin genes in defence responses against two root pathogens: the root-knot nematode Meloidogyne graminicola and the oomycete Pythium graminicola. The expression of rice thionin genes was observed to be differentially regulated by defence-related hormones, whereas all analysed genes were consistently down-regulated in M. graminicola-induced galls, at least until 7 days post-inoculation (dpi). Transgenic lines of Oryza sativa cv. Nipponbare overproducing OsTHI7 revealed decreased susceptibility to M. graminicola infection and P. graminicola colonization. Taken together, these results demonstrate the role of rice thionin genes in defence against two of the most damaging root pathogens attacking rice.

  10. Development of a Defence Distributed Computing Environment (DCE) Database Demonstrator,

    DTIC Science & Technology

    1995-11-01

    This report discusses the development of a Defence Distributed Computing Environment (DCE) database demonstrator program. The Demonstrator program...showcases the interoperability, portability, survivability and security features of Open Software Foundation’s Distributed Computing Environment.

  11. Damaged-self recognition in plant herbivore defence.

    PubMed

    Heil, Martin

    2009-07-01

    Feeding by herbivores induces plant defences, but we still do not know all the signals that mediate this response. Here, I argue that a general principle in this mediation is 'damaged-self recognition', that is, the perception of motifs by the plant that indicate disintegrated plant cells. Most defence-inducing molecules are (or contain) plant-derived motifs or disintegrate plant cells and thereby release defence elicitors. By perceiving the 'damaged self', plants can retain evolutionary control over their interactions with herbivores rather than allowing herbivores to dominate the interaction. The concept of 'damaged-self recognition' provides a paradigm for plant responses to herbivory and helps the search for the currently unknown elicitors of those defence responses, which have so far only been described at the phenotypic level.

  12. Chemical antipredator defence is linked to higher extinction risk

    PubMed Central

    2016-01-01

    Many attributes of species may be linked to contemporary extinction risk, though some such traits remain untested despite suggestions that they may be important. Here, I test whether a trait associated with higher background extinction rates, chemical antipredator defence, is also associated with current extinction risk, using amphibians as a model system—a group facing global population declines. I find that chemically defended species are approximately 60% more likely to be threatened than species without chemical defence, although the severity of the contemporary extinction risk may not relate to chemical defence. The results confirm that background and contemporary extinction rates can be predicted from the same traits, at least in certain cases. This suggests that associations between extinction risk and phenotypic traits can be temporally stable over long periods. The results also provide novel insights into the relevance of antipredator defences for species subject to conservation concerns. PMID:28018657

  13. Middle Devonian liverwort herbivory and antiherbivore defence.

    PubMed

    Labandeira, Conrad C; Tremblay, Susan L; Bartowski, Kenneth E; VanAller Hernick, Linda

    2014-04-01

    To test the extent of herbivory in early terrestrial ecosystems, we examined compression-impression specimens of the late Middle Devonian liverwort Metzgeriothallus sharonae, from the Catskill Delta deposit of eastern New York state. Shale fragments of field-collected specimens were processed by applying liquid nitrocellulose on exposed surfaces. After drying, the film coatings were lifted off and mounted on microscope slides for photography. Unprocessed fragments were photographed under cedarwood oil for enhanced contrast. An extensive repertoire of arthropodan-mediated herbivory was documented, representing three functional feeding groups and nine subordinate plant-arthropod damage types (DTs). The herbivory is the earliest occurrence of external foliage-feeding and galling in the terrestrial fossil record. Our evidence indicates that thallus oil body cells, similar to the terpenoid-containing oil bodies of modern liverworts, were probably involved in the chemical defence of M. sharonae against arthropod herbivores. Based on damage patterns of terrestrial plants and an accompanying but sparse body-fossil record, Devonian arthropodan herbivores were significantly smaller compared to those of the later Palaeozoic. These data collectively suggest that a broad spectrum herbivory may have had a more important role in early terrestrial ecosystems than previously thought.

  14. The dominant glutamic acid metabolic flux to produce γ-amino butyric acid over proline in Nicotiana tabacum leaves under water stress relates to its significant role in antioxidant activity.

    PubMed

    Liu, Cuili; Zhao, Li; Yu, Guanghui

    2011-08-01

    γ-Amino butyric acid (GABA) and proline play a crucial role in protecting plants during various environmental stresses. Their synthesis is from the common precursor glutamic acid, which is catalyzed by glutamate decarboxylase and Δ(1) -pyrroline-5-carboxylate synthetase respectively. However, the dominant pathway under water stress has not yet been established. To explore this, excised tobacco leaves were used to simulate a water-stress condition. The results showed GABA content was much higher than that of proline in leaves under water-deficit and non-water-deficit conditions. Specifically, the amount of GABA significantly increased compared to proline under continuous water loss for 16 h, indicating that GABA biosynthesis is the dominant pathway from glutamic acid metabolism under these conditions. Quantitative reverse transcription polymerase chain reaction and protein Western gel-blot analysis further confirmed this. To explore the function of GABA accumulation, a system producing superoxide anion (O(2) (-) ), peroxide hydrogen (H(2) O(2) ), and singlet oxygen ((1) O(2) ) was employed to investigate the scavenging role on free-radical production. The results demonstrated that the scavenging ability of GABA for O(2) (-) , H(2) O(2) , and (1) O(2) was significantly higher than that of proline. This indicated that GABA acts as an effective osmolyte to reduce the production of reactive oxygen species under water stress.

  15. The origin of exon 3 skipping of paternal GLOBOSA pre-mRNA in some Nicotiana tabacum lines correlates with a point mutation of the very last nucleotide of the exon.

    PubMed

    Fulneček, Jaroslav; Matyášek, Roman

    2016-04-01

    In plants, genome duplication followed by genome diversification and selection is recognized as a major evolutionary process. Rapid epigenetic and genetic changes that affect the transcription of parental genes are frequently observed after polyploidization. The pattern of alternative splicing is also frequently altered, yet the related molecular processes remain largely unresolved. Here, we study the inheritance and expression of parental variants of three floral organ identity genes in allotetraploid tobacco. DEFICIENS and GLOBOSA are B-class genes, and AGAMOUS is a C-class gene. Parental variants of these genes were found to be maintained in the tobacco genome, and the respective mRNAs were present in flower buds in comparable amounts. However, among five tobacco cultivars, we identified two in which the majority of paternal GLOBOSA pre-mRNA transcripts undergo exon 3 skipping, producing an mRNA with a premature termination codon. At the DNA level, we identified a G-A transition at the very last position of exon 3 in both cultivars. Although alternative splicing resulted in a dramatic decrease in full-length paternal GLOBOSA mRNA, no phenotypic effect was observed. Our finding likely serves as an example of the initiation of homoeolog diversification in a relatively young polyploid genome.

  16. Evaluating arguments during instigations of defence motivation and accuracy motivation.

    PubMed

    Liu, Cheng-Hong

    2017-05-01

    When people evaluate the strength of an argument, their motivations are likely to influence the evaluation. However, few studies have specifically investigated the influences of motivational factors on argument evaluation. This study examined the effects of defence and accuracy motivations on argument evaluation. According to the compatibility between the advocated positions of arguments and participants' prior beliefs and the objective strength of arguments, participants evaluated four types of arguments: compatible-strong, compatible-weak, incompatible-strong, and incompatible-weak arguments. Experiment 1 revealed that participants possessing a high defence motivation rated compatible-weak arguments as stronger and incompatible-strong ones as weaker than participants possessing a low defence motivation. However, the strength ratings between the high and low defence groups regarding both compatible-strong and incompatible-weak arguments were similar. Experiment 2 revealed that when participants possessed a high accuracy motivation, they rated compatible-weak arguments as weaker and incompatible-strong ones as stronger than when they possessed a low accuracy motivation. However, participants' ratings on both compatible-strong and incompatible-weak arguments were similar when comparing high and low accuracy conditions. The results suggest that defence and accuracy motivations are two major motives influencing argument evaluation. However, they primarily influence the evaluation results for compatible-weak and incompatible-strong arguments, but not for compatible-strong and incompatible-weak arguments.

  17. Defence and Security Research Coexistence, Coherence, and Convergence

    NASA Astrophysics Data System (ADS)

    Breant, Christian; Karock, Ulrich

    Defence and security research have coexisted at the European Union level since the inception of the European Defence Agency (EDA). The agency was established under a Joint Action of the Council of Ministers on 12 July 2004, "to support the Member States and the Council in their effort to improve European defence capabilities in the field of crisis management and to sustain the European Security and Defence Policy as it stands now and develops in the future".1 The political decision to create the EDA was taken at the Thessaloniki European Council on 19 and 20 June 2003. Heads of State or Government tasked the Council bodies to undertake the requisite actions, in the course of 2004, to create an intergovernmental agency in the field of defence capabilities development, research, acquisition and armaments. The EDA has been located in Brussels right from the start. It is an intergovernmental EU agency under the Council's authority within the single institutional framework of the Union. It performs its mission in close cooperation with its participating Member States (pMS) and the European institutional actors.

  18. Population structure and genetic diversity of Phytophthora nicotianae from tobacco in Georgia

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Black shank caused by Phytophthora nicotianae occurs worldwide and is responsible for significant yield loss in tobacco production in Georgia. Management of the disease has primarily relied on utilization of tobacco cultivars with resistance to race 0 of the pathogen and application of the fungicide...

  19. Genetic Analysis of Phytophthora nicotianae Populations from Different Hosts Using Microsatellite Markers.

    PubMed

    Biasi, Antonio; Martin, Frank N; Cacciola, Santa O; di San Lio, Gaetano Magnano; Grünwald, Niklaus J; Schena, Leonardo

    2016-09-01

    In all, 231 isolates of Phytophthora nicotianae representing 14 populations from different host genera, including agricultural crops (Citrus, Nicotiana, and Lycopersicon), potted ornamental species in nurseries (Lavandula, Convolvulus, Myrtus, Correa, and Ruta), and other plant genera were characterized using simple-sequence repeat markers. In total, 99 multilocus genotypes (MLG) were identified, revealing a strong association between genetic grouping and host of recovery, with most MLG being associated with a single host genus. Significant differences in the structure of populations were revealed but clonality prevailed in all populations. Isolates from Citrus were found to be genetically related regardless of their geographic origin and were characterized by high genetic uniformity and high inbreeding coefficients. Higher variability was observed for other populations and a significant geographical structuring was determined for isolates from Nicotiana. Detected differences were related to the propagation and cultivation systems of different crops. Isolates obtained from Citrus spp. are more likely to be distributed worldwide with infected plant material whereas Nicotiana and Lycopersicon spp. are propagated by seed, which would not contribute to the spread of the pathogen and result in a greater chance for geographic isolation of lineages. With regard to ornamental species in nurseries, the high genetic variation is likely the result of the admixture of diverse pathogen genotypes through the trade of infected plant material from various geographic origins, the presence of several hosts in the same nursery, and genetic recombination through sexual reproduction of this heterothallic species.

  20. Anaerobic soil disinfestation reduces survival and infectivity of Phytophthora nicotianae chlamydospores in pepper

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Phytophthora nicotianae is the principal causal agent of root and crown rot disease of pepper plants in Extremadura (western Spain), a spring-summer crop in this region. Preplant soil treatment by anaerobic soil disinfestation (ASD) may effectively control plant pathogens in many crop production sys...

  1. Identification and validation of polymorphic microsatellite loci for the analysis of Phytophthora nicotianae populations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A large number of SSR loci were screened in the genomic assemblies of 14 different isolates of Phytophthora nicotianae and primers were developed for amplification of 17 markers distributed among different contigs. These loci were highly polymorphic and amplified from genetically distant isolates of...

  2. Calcium Efflux as a Component of Hypersensitive Response of Nicotiana benthamiana to Pseudomonas syringae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Using a model plant Nicotiana benthamiana we have demonstrated that initial calcium uptake in response to HR (hypersensitive response)-causing pathogen, P. syringae pv syringae 61 is followed by the net calcium efflux initiated at about 12 hrs after the bacterial challenge and sustained for at least...

  3. Product variability of the 'cineole cassette' monoterpene synthases of related Nicotiana species.

    PubMed

    Fähnrich, Anke; Krause, Katrin; Piechulla, Birgit

    2011-11-01

    Nicotiana species of the section Alatae characteristically emit the floral scent compounds of the 'cineole cassette' comprising 1,8-cineole, limonene, myrcene, α-pinene, β-pinene, sabinene, and α-terpineol. We successfully isolated genes of Nicotiana alata and Nicotiana langsdorfii that encoded enzymes, which produced the characteristic monoterpenes of this 'cineole cassette' with α-terpineol being most abundant in the volatile spectra. The amino acid sequences of both terpineol synthases were 99% identical. The enzymes cluster in a monophyletic branch together with the closely related cineole synthase of Nicotiana suaveolens and monoterpene synthase 1 of Solanum lycopersicum. The cyclization reactions (α-terpineol to 1,8-cineole) of the terpineol synthases of N. alata and N. langsdorfii were less efficient compared to the 'cineole cassette' monoterpene synthases of Arabidopsis thaliana, N. suaveolens, Salvia fruticosa, Salvia officinalis, and Citrus unshiu. The terpineol synthases of N. alata and N. langsdorfii were localized in pistils and in the adaxial and abaxial epidermis of the petals. The enzyme activities reached their maxima at the second day after anthesis when flowers were fully opened and the enzyme activity in N. alata was highest at the transition from day to night (diurnal rhythm).

  4. Effects of hydrostatic pressure, agitation and CO2 stress on Phytophthora nicotianae zoospore survival

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Phytophthora nicotianae Breda de Haan was used as a model pathogen to investigate the effects of hydrostatic pressure, agitation, and aeration with CO2 or breathable air on the survival of Phytophthora zoospores in water. Injecting CO2 into 2 liters of zoospore-infested water for 5 min at 110.4 ml ...

  5. Plant defence as a complex and changing phenotype throughout ontogeny

    PubMed Central

    Ochoa-López, Sofía; Villamil, Nora; Zedillo-Avelleyra, Paulina; Boege, Karina

    2015-01-01

    Background and Aims Ontogenetic changes in anti-herbivore defences are common and result from variation in resource availability and herbivore damage throughout plant development. However, little is known about the simultaneous changes of multiple defences across the entire development of plants, and how such changes affect plant damage in the field. The aim of this study was to assess if changes in the major types of plant resistance and tolerance can explain natural herbivore damage throughout plant ontogeny. Methods An assessment was made of how six defensive traits, including physical, chemical and biotic resistance, simultaneously change across the major transitions of plant development, from seedlings to reproductive stages of Turnera velutina growing in the greenhouse. In addition, an experiment was performed to assess how plant tolerance to artificial damage to leaves changed throughout ontogeny. Finally, leaf damage by herbivores was evaluated in a natural population. Key Results The observed ontogenetic trajectories of all defences were significantly different, sometimes showing opposite directions of change. Whereas trichome density, leaf toughness, extrafloral nectary abundance and nectar production increased, hydrogen cyanide and compensatory responses decreased throughout plant development, from seedlings to reproductive plants. Only water content was higher at the intermediate juvenile ontogenetic stages. Surveys in a natural population over 3 years showed that herbivores consumed more tissue from juvenile plants than from younger seedlings or older reproductive plants. This is consistent with the fact that juvenile plants were the least defended stage. Conclusions The results suggest that defensive trajectories are a mixed result of predictions by the Optimal Defence Theory and the Growth–Differentiation Balance Hypothesis. The study emphasizes the importance of incorporating multiple defences and plant ontogeny into further studies for a more

  6. Comparative genomics tools applied to bioterrorism defence.

    PubMed

    Slezak, Tom; Kuczmarski, Tom; Ott, Linda; Torres, Clinton; Medeiros, Dan; Smith, Jason; Truitt, Brian; Mulakken, Nisha; Lam, Marisa; Vitalis, Elizabeth; Zemla, Adam; Zhou, Carol Ecale; Gardner, Shea

    2003-06-01

    Rapid advances in the genomic sequencing of bacteria and viruses over the past few years have made it possible to consider sequencing the genomes of all pathogens that affect humans and the crops and livestock upon which our lives depend. Recent events make it imperative that full genome sequencing be accomplished as soon as possible for pathogens that could be used as weapons of mass destruction or disruption. This sequence information must be exploited to provide rapid and accurate diagnostics to identify pathogens and distinguish them from harmless near-neighbours and hoaxes. The Chem-Bio Non-Proliferation (CBNP) programme of the US Department of Energy (DOE) began a large-scale effort of pathogen detection in early 2000 when it was announced that the DOE would be providing bio-security at the 2002 Winter Olympic Games in Salt Lake City, Utah. Our team at the Lawrence Livermore National Lab (LLNL) was given the task of developing reliable and validated assays for a number of the most likely bioterrorist agents. The short timeline led us to devise a novel system that utilised whole-genome comparison methods to rapidly focus on parts of the pathogen genomes that had a high probability of being unique. Assays developed with this approach have been validated by the Centers for Disease Control (CDC). They were used at the 2002 Winter Olympics, have entered the public health system, and have been in continual use for non-publicised aspects of homeland defence since autumn 2001. Assays have been developed for all major threat list agents for which adequate genomic sequence is available, as well as for other pathogens requested by various government agencies. Collaborations with comparative genomics algorithm developers have enabled our LLNL team to make major advances in pathogen detection, since many of the existing tools simply did not scale well enough to be of practical use for this application. It is hoped that a discussion of a real-life practical application of

  7. Screening micro-organisms for cadmium absorption from aqueous solution and cadmium absorption properties of Arthrobacter nicotianae.

    PubMed

    Tsuruta, Takehiko; Umenai, Daishi; Hatano, Tomonobu; Hirajima, Tsuyoshi; Sasaki, Keiko

    2014-01-01

    To obtain basic information on how microbial cells absorb cadmium from aqueous solution, we examined cadmium absorption in various micro-organisms. Of 51 micro-organism strains tested, we found that some Gram-positive bacteria, such as, Arthrobacter nicotianae and Bacillus subtilis, and some actinomycetes, such as, Streptomyces flavoviridis and S. levoris were highly capable of absorbing cadmium from an aqueous solution. A. nicotianae absorbed the largest amount of cadmium, over 800 μmol cadmium per gram of dry wt. cells. However, cadmium absorption by A. nicotianae was affected by the solution pH, cadmium concentration, and cell density. The absorption of cadmium was very rapid. Some factors that affected cadmium absorption by A. nicotianae cells were also discussed.

  8. Sense Making in the Australian Defence Organisation (ADO) Intelligence Community

    DTIC Science & Technology

    2005-07-01

    Sense Making in the Australian Defence Organisation (ADO) Intelligence Community Mark Burnett, Pete Wooding * and Paul Prekop...3 And it is possible to inter-relate all three models – see Rousseau and Breton 2005. DSTO-GD...worthy of more detailed consideration. DSTO-GD-0440 22 References Breton , R. and Rousseau, R. (2005), "The C-OODA: A Cognitive Version

  9. Communal range defence in primates as a public goods dilemma

    PubMed Central

    Willems, Erik P.; Arseneau, T. Jean. M.; Schleuning, Xenia; van Schaik, Carel P.

    2015-01-01

    Classic socio-ecological theory holds that the occurrence of aggressive range defence is primarily driven by ecological incentives, most notably by the economic defendability of an area or the resources it contains. While this ecological cost–benefit framework has great explanatory power in solitary or pair-living species, comparative work on group-living primates has always found economic defendability to be a necessary, but not sufficient condition to account for the distribution of effective range defence across the taxon. This mismatch between theory and observation has recently been ascribed to a collective action problem among group members in, what is more informatively viewed as, a public goods dilemma: mounting effective defence of a communal range against intrusions by outgroup conspecifics. We here further develop this framework, and report on analyses at three levels of biological organization: across species, across populations within a single lineage and across groups and individuals within a single population. We find that communal range defence in primates very rarely involves collective action sensu stricto and that it is best interpreted as the outcome of opportunistic and strategic individual-level decisions. Whether the public good of a defended communal range is produced by solitary, joint or collective action is thus the outcome of the interplay between the unique characteristics of each individual, local and current socio-ecological conditions, and fundamental life-history traits of the species. PMID:26503678

  10. A Review of Enterprise Architecture Use in Defence

    DTIC Science & Technology

    2014-09-01

    functions in Defence. The concept of CIS support to operations recognises the intrinsic relationship between information in its broadest sense and...guidance was provided on the conduct of the ARM, including considerations such as information to be provided, reviewer requirements, attendance quorum

  11. The Case to Widen Defence Acquisition Research Paradigms

    DTIC Science & Technology

    2012-04-30

    can be conducted Key issues associated with changes in acquisition practices Acquisition will become increasingly dependent on social science...military have been outsourced to the privately owned defence industrial base (DIB). This change has seen a movement away from procurement to... changes raises the question: Are the traditional research methodologies previously employed to examine procurement phenomena adequate for modern

  12. Evolution of hosts paying manifold costs of defence.

    PubMed

    Cressler, Clayton E; Graham, Andrea L; Day, Troy

    2015-04-07

    Hosts are expected to incur several physiological costs in defending against parasites. These include constitutive energetic (or other resource) costs of a defence system, facultative resource costs of deploying defences when parasites strike, and immunopathological costs of collateral damage. Here, we investigate the evolution of host recovery rates, varying the source and magnitude of immune costs. In line with previous work, we find that hosts paying facultative resource costs evolve faster recovery rates than hosts paying constitutive costs. However, recovery rate is more sensitive to changes in facultative costs, potentially explaining why constitutive costs are hard to detect empirically. Moreover, we find that immunopathology costs which increase with recovery rate can erode the benefits of defence, promoting chronicity of infection. Immunopathology can also lead to hosts evolving low recovery rate in response to virulent parasites. Furthermore, when immunopathology reduces fecundity as recovery rate increases (e.g. as for T-cell responses to urogenital chlamydiosis), then recovery and reproductive rates do not covary as predicted in eco-immunology. These results suggest that immunopathological and resource costs have qualitatively different effects on host evolution and that embracing the complexity of immune costs may be essential for explaining variability in immune defence in nature.

  13. Communal range defence in primates as a public goods dilemma.

    PubMed

    Willems, Erik P; Arseneau, T Jean M; Schleuning, Xenia; van Schaik, Carel P

    2015-12-05

    Classic socio-ecological theory holds that the occurrence of aggressive range defence is primarily driven by ecological incentives, most notably by the economic defendability of an area or the resources it contains. While this ecological cost-benefit framework has great explanatory power in solitary or pair-living species, comparative work on group-living primates has always found economic defendability to be a necessary, but not sufficient condition to account for the distribution of effective range defence across the taxon. This mismatch between theory and observation has recently been ascribed to a collective action problem among group members in, what is more informatively viewed as, a public goods dilemma: mounting effective defence of a communal range against intrusions by outgroup conspecifics. We here further develop this framework, and report on analyses at three levels of biological organization: across species, across populations within a single lineage and across groups and individuals within a single population. We find that communal range defence in primates very rarely involves collective action sensu stricto and that it is best interpreted as the outcome of opportunistic and strategic individual-level decisions. Whether the public good of a defended communal range is produced by solitary, joint or collective action is thus the outcome of the interplay between the unique characteristics of each individual, local and current socio-ecological conditions, and fundamental life-history traits of the species.

  14. Australia’s National Security: A Defence Update 2003

    DTIC Science & Technology

    2003-01-01

    Australia’s response to the Bali bombing 13 Bastille Middle East Forward deployment of personnel in support of UN efforts to disarm Iraq Operation Operation... Bastille Operation Operation Citadel report.p65 21/2/03, 8:5427 DEFENCE UPDATE 200328 D PS N O V 01 0/ 02 report.p65 21/2/03, 8:5428

  15. The Strategic Development of the Trinidad and Tobago Defence Force

    DTIC Science & Technology

    2009-06-12

    and ecommerce . In combination, these driving forces of change led to an explosion in world trade, an exponential increase in business ...and Tobago Defence Force‘s approach to organization strategy. In defining this term, the author slightly amends Thompson and Strickland‘s business ...extreme competition and intense rivalry especially between American and Japanese businesses . 15 After many decades of domination, American businesses

  16. Landscape settings as part of earth wall systems for defence

    NASA Astrophysics Data System (ADS)

    van den Ancker, Hanneke; Jungerius, Pieter Dirk

    2013-04-01

    Remnants of earth wall systems from different periods are preserved in many European countries. They were built for different functions, such as defence, demarcating ownership or keeping wild animals or cattle in or out a terrain, and often changed function over time. Earth walls date from a past in which man had limited access to man- and horsepower. In the case of defence systems, our ancestors made use of the landscape settings to improve the strength. The poster gives an overview of landscape settings used for this purpose, from prehistoric up to medieval age, for building round and linear earth wall defence systems. Round earth walls systems are found on: • High viewpoints along a river, often in combination with marshland at its feet, • Almost completely cut-off meanders of antecedent rivers. This natural setting offered an ideal defence. It allowed an almost 360 degree view and exposed the enemy for a long time when passing the river, while the steep slopes and narrow entrance made the hill fort difficult to access, • Islands in lakes, • Bordering a lake at one side, • Confluences of rivers, • Hills near the sea and a natural harbour with possibilities for defence, • High flat hill tops of medium size with steep sides. Of each situation examples are presented. Linear earth wall defence systems For linear defence earth walls no overview of landscape settings can be given, for lack of sufficient data. The Celtic, 10 m steep Beech Bottom Dyke earth wall system from around 20 A.D. connects two steeply incised river valleys. For building the Hadrian Wall (UK) the Romans made use of earth walls paralleling the steepest cuesta of the Cheviot hills. The Viking Danewerk (Ger), was built on push moraines and used the coastal marsh lands at their feet for defence. And the defence of the earth wall around the Velder (NL, probably 13th century) made use of the many small streams crossing this marshy coversand landscape, by diverting them into a canal

  17. Host-defence-related proteins in cows' milk.

    PubMed

    Wheeler, T T; Smolenski, G A; Harris, D P; Gupta, S K; Haigh, B J; Broadhurst, M K; Molenaar, A J; Stelwagen, K

    2012-03-01

    Milk is a source of bioactive molecules with wide-ranging functions. Among these, the immune properties have been the best characterised. In recent years, it has become apparent that besides the immunoglobulins, milk also contains a range of minor immune-related proteins that collectively form a significant first line of defence against pathogens, acting both within the mammary gland itself as well as in the digestive tract of the suckling neonate. We have used proteomics technologies to characterise the repertoire of host-defence-related milk proteins in detail, revealing more than 100 distinct gene products in milk, of which at least 15 are known host-defence-related proteins. Those having intrinsic antimicrobial activity likely function as effector proteins of the local mucosal immune defence (e.g. defensins, cathelicidins and the calgranulins). Here, we focus on the activities and biological roles of the cathelicidins and mammary serum amyloid A. The function of the immune-related milk proteins that do not have intrinsic antimicrobial activity is also discussed, notably lipopolysaccharide-binding protein, RNase4, RNase5/angiogenin and cartilage-glycoprotein 39 kDa. Evidence is shown that at least some of these facilitate recognition of microbes, resulting in the activation of innate immune signalling pathways in cells associated with the mammary and/or gut mucosal surface. Finally, the contribution of the bacteria in milk to its functionality is discussed. These investigations are elucidating how an effective first line of defence is achieved in the bovine mammary gland and how milk contributes to optimal digestive function in the suckling calf. This study will contribute to a better understanding of the health benefits of milk, as well as to the development of high-value ingredients from milk.

  18. BABA and Phytophthora nicotianae Induce Resistance to Phytophthora capsici in Chile Pepper (Capsicum annuum)

    PubMed Central

    Stamler, Rio A.; Holguin, Omar; Dungan, Barry; Schaub, Tanner; Sanogo, Soumaila; Goldberg, Natalie; Randall, Jennifer J.

    2015-01-01

    Induced resistance in plants is a systemic response to certain microorganisms or chemicals that enhances basal defense responses during subsequent plant infection by pathogens. Inoculation of chile pepper with zoospores of non-host Phytophthora nicotianae or the chemical elicitor beta-aminobutyric acid (BABA) significantly inhibited foliar blight caused by Phytophthora capsici. Tissue extract analyses by GC/MS identified conserved change in certain metabolite concentrations following P. nicotianae or BABA treatment. Induced chile pepper plants had reduced concentrations of sucrose and TCA cycle intermediates and increased concentrations of specific hexose-phosphates, hexose-disaccharides and amino acids. Galactose, which increased significantly in induced chile pepper plants, was shown to inhibit growth of P. capsici in a plate assay. PMID:26020237

  19. The N-terminal fragment of the tomato torrado virus RNA1-encoded polyprotein induces a hypersensitive response (HR)-like reaction in Nicotiana benthamiana.

    PubMed

    Wieczorek, Przemysław; Obrępalska-Stęplowska, Aleksandra

    2016-07-01

    The hypersensitive response (HR) is a defence reaction observed during incompatible plant-pathogen interactions in plants infected with a wide range of fungi, bacteria and viruses. Here, we show that an N-terminal polyprotein fragment encoded by tomato torrado virus RNA1, located between the first ATG codon and the protease cofactor (ProCo) motif, induces an HR-like reaction in Nicotiana benthamiana. Agrobacterium tumefaciens-mediated transient expression of the first 105 amino acids (the calculated molecular weight of the fragment was ca. 11.33 kDa, hereafter refered to as the 11K domain) from ToTV RNA1 induced an HR-like phenotype in infiltrated leaves. To investigate whether the 11K domain could influence the virulence and pathogenicity of a recombinant virus, we created a potato virus X (PVX) with the 11K coding sequence inserted under a duplicated coat protein promoter. We found that 11K substantially increased the virulence of the recombinant virus. Disease phenotype induced in N. benthamiana by PVX-11K was characterized by strong local and systemic necrosis. This was not observed when the 11K domain was expressed from PVX in an antisense orientation. Further analyses revealed that the 11K domain could not suppress posttranscriptional gene silencing (PTGS) of green fluorescent protein (GFP) in the N. benthamiana 16c line. In silico analysis of the predicted secondary structure of the 11K domain indicated the presence of two putative helices that are highly conserved in tomato-infecting representatives of the genus Torradovirus.

  20. The Ups and Downs of Genome Size Evolution in Polyploid Species of Nicotiana (Solanaceae)

    PubMed Central

    Leitch, I. J.; Hanson, L.; Lim, K. Y.; Kovarik, A.; Chase, M. W.; Clarkson, J. J.; Leitch, A. R.

    2008-01-01

    Background In studies looking at individual polyploid species, the most common patterns of genomic change are that either genome size in the polyploid is additive (i.e. the sum of parental genome donors) or there is evidence of genome downsizing. Reports showing an increase in genome size are rare. In a large-scale analysis of 3008 species, genome downsizing was shown to be a widespread biological response to polyploidy. Polyploidy in the genus Nicotiana (Solanaceae) is common with approx. 40 % of the approx. 75 species being allotetraploid. Recent advances in understanding phylogenetic relationships of Nicotiana species and dating polyploid formation enable a temporal dimension to be added to the analysis of genome size evolution in these polyploids. Methods Genome sizes were measured in 18 species of Nicotiana (nine diploids and nine polyploids) ranging in age from <200 000 years to approx. 4·5 Myr old, to determine the direction and extent of genome size change following polyploidy. These data were combined with data from genomic in situ hybridization and increasing amounts of information on sequence composition in Nicotiana to provide insights into the molecular basis of genome size changes. Key Results and Conclusions By comparing the expected genome size of the polyploid (based on summing the genome size of species identified as either a parent or most closely related to the diploid progenitors) with the observed genome size, four polyploids showed genome downsizing and five showed increases. There was no discernable pattern in the direction of genome size change with age of polyploids, although with increasing age the amount of genome size change increased. In older polyploids (approx. 4·5 million years old) the increase in genome size was associated with loss of detectable genomic in situ hybridization signal, whereas some hybridization signal was still detected in species exhibiting genome downsizing. The possible significance of these results is

  1. A novel gene required for cercosporin toxin resistance in the fungus Cercospora nicotianae.

    PubMed

    Chung, K R; Jenns, A E; Ehrenshaft, M; Daub, M E

    1999-09-01

    Cercosporin, a photosensitizing perylenequinone toxin produced by the plant pathogenic Cercospora fungi, generates the highly toxic singlet oxygen (1O2) upon exposure to light. Cercosporin shows broad toxicity against a wide range of organisms, including bacteria, fungi, plants, and animals; however, Cercospora fungi are resistant to its effects. A novel gene, crg1 (cercosporin-resistance gene) was isolated from a wild-type strain of C. nicotianae by genetic complementation of a C. nicotianae mutant (CS10) which is cercosporin sensitive and down-regulated in cercosporin production. Sequence analysis indicated that crg1 encodes a putative protein of 550 amino acids with four putative transmembrane helical regions, however CRG1 shows no strong similarity to any other protein in sequence databases. Northern analysis identified two transcripts (4.5 and 2.6 kb) that are unaffected by the presence of light or cercosporin. Southern analysis demonstrated that crg1 is present in a single copy in the C. nicotianae genome and can be detected only in Cercospora species. Targeted disruption of crg1 resulted in mutants that, like CS10, are sensitive to cercosporin. However, unlike CS10, crg1 disruption mutants are not down-regulated in toxin production. Both CS10 and the crg1 disruption mutants are unaffected in their response to other 1O2-generating photosensitizers, suggesting that CRG1 functions specifically against cercosporin, rather than against 1O2.

  2. A Comparative Analysis of Sonic Defences in Bombycoidea Caterpillars

    PubMed Central

    Bura, Veronica L.; Kawahara, Akito Y.; Yack, Jayne E.

    2016-01-01

    Caterpillars have long been used as models for studying animal defence. Their impressive armour, including flamboyant warning colours, poisonous spines, irritating sprays, and mimicry of plant parts, snakes and bird droppings, has been extensively documented. But research has mainly focused on visual and chemical displays. Here we show that some caterpillars also exhibit sonic displays. During simulated attacks, 45% of 38 genera and 33% of 61 species of silk and hawkmoth caterpillars (Bombycoidea) produced sounds. Sonic caterpillars are found in many distantly-related groups of Bombycoidea, and have evolved four distinct sound types- clicks, chirps, whistles and vocalizations. We propose that different sounds convey different messages, with some designed to warn of a chemical defence and others, to startle predators. This research underscores the importance of exploring acoustic communication in juvenile insects, and provides a model system to explore how different signals have evolved to frighten, warn or even trick predators. PMID:27510510

  3. Flow cytometry as a tool to quantify oyster defence mechanisms.

    PubMed

    Goedken, Michael; De Guise, Sylvain

    2004-04-01

    The fast growing oyster aquaculture industry is greatly hindered by Perkinsus marinus and Haplosporidium nelsoni which can kill up to 80% of the production. The relationship between parasites and oyster defence mechanisms is unclear. Two defence mechanisms of the Eastern Oyster (Crassostrea virginica) were quantified at the single cell level utilising flow cytometry. Phagocytosis was measured using fluorescent beads. Respiratory burst activity was quantified as the H2O2-specific increase in dichlorofluorescein-associated fluorescence upon stimulation. These two assays distinguished three populations of haemocytes (granulocytes, hyalinocytes and intermediate cells) with unique functional characteristics. Granulocytes were most active at phagocytosis and H2O2 production while hyalinocytes were relatively inactive. The intermediate cells had moderate phagocytic and respiratory burst activity. Flow cytometry can rapidly, accurately and directly quantify the morphology and function of a large number of individual cells, and will lead to a better understanding of the bivalve immune system.

  4. Upstream and downstream signals of nitric oxide in pathogen defence.

    PubMed

    Gaupels, Frank; Kuruthukulangarakoola, Gitto Thomas; Durner, Jörg

    2011-12-01

    Nitric oxide (NO) is now recognised as a crucial player in plant defence against pathogens. Considerable progress has been made in defining upstream and downstream signals of NO. Recently, MAP kinases, cyclic nucleotide phosphates, calcium and phosphatidic acid were demonstrated to be involved in pathogen-induced NO-production. However, the search for inducers of NO synthesis is difficult because of the still ambiguous enzymatic source of NO. Accumulation of NO triggers signal transduction by other second messengers. Here we depict NON-EXPRESSOR OF PATHOGENESIS-RELATED 1 and glyceraldehyde-3-phosphate dehydrogenase as central redox switches translating NO redox signalling into cellular responses. Although the exact position of NO in defence signal networks is unresolved at last some NO-related signal cascades are emerging.

  5. Military social work in the South African National Defence Force.

    PubMed

    Kruger, A; Van Breda, A D

    2001-11-01

    The transformation of the South African National Defence Force has prompted a critical reassessment of the Directorate of Social Work. As a result, the directorate realized the need for a formal business plan to align the profession strategically with the core business of the military system. After completion of the business plan, the need for a unique military social work practice model was identified. Such a model should present social workers with a strategy for the achievement of the goals and objectives of the business plan. The practice model rests on two key concepts: binocular vision and practice positions. Since the onset of the transformation process in the South African National Defence Force, these two documents have reflected the changing milieu within which social work is practiced. The main concepts of these documents are presented.

  6. A Comparative Analysis of Sonic Defences in Bombycoidea Caterpillars.

    PubMed

    Bura, Veronica L; Kawahara, Akito Y; Yack, Jayne E

    2016-08-11

    Caterpillars have long been used as models for studying animal defence. Their impressive armour, including flamboyant warning colours, poisonous spines, irritating sprays, and mimicry of plant parts, snakes and bird droppings, has been extensively documented. But research has mainly focused on visual and chemical displays. Here we show that some caterpillars also exhibit sonic displays. During simulated attacks, 45% of 38 genera and 33% of 61 species of silk and hawkmoth caterpillars (Bombycoidea) produced sounds. Sonic caterpillars are found in many distantly-related groups of Bombycoidea, and have evolved four distinct sound types- clicks, chirps, whistles and vocalizations. We propose that different sounds convey different messages, with some designed to warn of a chemical defence and others, to startle predators. This research underscores the importance of exploring acoustic communication in juvenile insects, and provides a model system to explore how different signals have evolved to frighten, warn or even trick predators.

  7. Australian Defence Risk Management Framework: A Comparative Study

    DTIC Science & Technology

    2005-02-01

    contemplated well ahead of the traditional corporate and business - planning processes. There is also an upside to using risk management, i.e. improving...place to properly manage these risks; • To ensure that risk management is integrated into Defence�s business planning processes; and • To establish...and based on AS/NZS 4360:1999 and the Defence Risk Management Policy. It prescribes risk management to be integrated into the business planning process

  8. Australian DefenceScience. Volume 13, Number 4, Summer

    DTIC Science & Technology

    2006-01-01

    fuselage and cockpit, mid and aft fuselage, empennage , wing , wing and fuselage intersection, and finally engine nacelles. A photographic survey of...own rivet lines as a guide. Areas of high curvature in three dimensions, like the engine nacelles, empennage - fuselage intersection and wing -fuselage...tony.cox@dsto.defence.gov.au Design and illustration: Rebekah Meere Phone: 61 3 9626 7141 Fax: 61 3 9626 7133 e-mail: rebekah.meere

  9. Debugging and Logging Services for Defence Service Oriented Architectures

    DTIC Science & Technology

    2012-02-01

    UNCLASSIFIED Debugging and Logging Services for Defence Service Oriented Architectures Michael Pilling Command, Control, Communications and...paralled de- bugging , SOAs introduce the complexity of significant parts of one’s programs being provided by others. This paper examines the features of...timestamps will allow programmers fixing bugs to avoid many spurious symptoms and get a clearer picture of the problem at hand. • Logging of

  10. Ministry of Defence Main Estimates 2009-10

    DTIC Science & Technology

    2009-07-02

    10 military equipment for use in the operational environment (e.g. further adaptations to Tornado aircraft and Lynx and Merlin helicopters). UORs...Defence Main Estimates 2009–10 13 21. A Departmental Minute laid before the House on the same day that we received the Government response to our...modifications to military equipment for use in the operational environment (eg further adaptations to Tornado aircraft and Lynx and Merlin helicopters). UORs by

  11. A Framework for the Automation of Air Defence Systems

    DTIC Science & Technology

    2000-04-01

    and Integration. [les Avancees en concepts systemes pour vehicules et en integration] To order the complete compilation report, use: ADA381871 The...are also inherent attack a target. to an autonomous architecture. The main difference The major advantages of distributing data to all between our...available for a single air defence task. [6] Krogmann, U., Towards Autonomous Systems, in AGAR.D Lecture Series 210, Advances in Soft- 5 Conclusions

  12. Signalling network construction for modelling plant defence response.

    PubMed

    Miljkovic, Dragana; Stare, Tjaša; Mozetič, Igor; Podpečan, Vid; Petek, Marko; Witek, Kamil; Dermastia, Marina; Lavrač, Nada; Gruden, Kristina

    2012-01-01

    Plant defence signalling response against various pathogens, including viruses, is a complex phenomenon. In resistant interaction a plant cell perceives the pathogen signal, transduces it within the cell and performs a reprogramming of the cell metabolism leading to the pathogen replication arrest. This work focuses on signalling pathways crucial for the plant defence response, i.e., the salicylic acid, jasmonic acid and ethylene signal transduction pathways, in the Arabidopsis thaliana model plant. The initial signalling network topology was constructed manually by defining the representation formalism, encoding the information from public databases and literature, and composing a pathway diagram. The manually constructed network structure consists of 175 components and 387 reactions. In order to complement the network topology with possibly missing relations, a new approach to automated information extraction from biological literature was developed. This approach, named Bio3graph, allows for automated extraction of biological relations from the literature, resulting in a set of (component1, reaction, component2) triplets and composing a graph structure which can be visualised, compared to the manually constructed topology and examined by the experts. Using a plant defence response vocabulary of components and reaction types, Bio3graph was applied to a set of 9,586 relevant full text articles, resulting in 137 newly detected reactions between the components. Finally, the manually constructed topology and the new reactions were merged to form a network structure consisting of 175 components and 524 reactions. The resulting pathway diagram of plant defence signalling represents a valuable source for further computational modelling and interpretation of omics data. The developed Bio3graph approach, implemented as an executable language processing and graph visualisation workflow, is publically available at http://ropot.ijs.si/bio3graph/and can be utilised for

  13. Parallel evolution of passive and active defence in land snails

    PubMed Central

    Morii, Yuta; Prozorova, Larisa; Chiba, Satoshi

    2016-01-01

    Predator-prey interactions are major processes promoting phenotypic evolution. However, it remains unclear how predation causes morphological and behavioural diversity in prey species and how it might lead to speciation. Here, we show that substantial divergence in the phenotypic traits of prey species has occurred among closely related land snails as a result of adaptation to predator attacks. This caused the divergence of defensive strategies into two alternatives: passive defence and active defence. Phenotypic traits of the subarctic Karaftohelix land snail have undergone radiation in northeast Asia, and distinctive morphotypes generally coexist in the same regions. In these land snails, we documented two alternative defence behaviours against predation by malacophagous beetles. Furthermore, the behaviours are potentially associated with differences in shell morphology. In addition, molecular phylogenetic analyses indicated that these alternative strategies against predation arose independently on the islands and on the continent suggesting that anti-predator adaptation is a major cause of phenotypic diversity in these snails. Finally, we suggest the potential speciation of Karaftohelix snails as a result of the divergence of defensive strategies into passive and active behaviours and the possibility of species radiation due to anti-predatory adaptations. PMID:27833102

  14. The circadian clock and defence signalling in plants.

    PubMed

    Sharma, Mayank; Bhatt, Deepesh

    2015-02-01

    The circadian clock is the internal time-keeping machinery in higher organisms. Cross-talk between the circadian clock and a diverse range of physiological processes in plants, including stress acclimatization, hormone signalling, photomorphogenesis and defence signalling, is currently being explored. Recent studies on circadian clock genes and genes involved in defence signalling have indicated a possible reciprocal interaction between the two. It has been proposed that the circadian clock shapes the outcome of plant-pathogen interactions. In this review, we highlight the studies carried out so far on two model plant pathogens, namely Pseudomonas syringae and Hyaloperonospora arabidopsidis, and the involvement of the circadian clock in gating effector-triggered immunity and pathogen-associated molecular pattern-triggered immunity. We focus on how the circadian clock gates the expression of various stress-related transcripts in a prolific manner to enhance plant fitness. An understanding of this dynamic relationship between clock and stress will open up new avenues in the understanding of endogenous mechanisms of defence signalling in plants.

  15. Sensory neuron regulation of gastrointestinal inflammation and bacterial host defence.

    PubMed

    Lai, N Y; Mills, K; Chiu, I M

    2017-02-02

    Sensory neurons in the gastrointestinal tract have multifaceted roles in maintaining homeostasis, detecting danger and initiating protective responses. The gastrointestinal tract is innervated by three types of sensory neurons: dorsal root ganglia, nodose/jugular ganglia and intrinsic primary afferent neurons. Here, we examine how these distinct sensory neurons and their signal transducers participate in regulating gastrointestinal inflammation and host defence. Sensory neurons are equipped with molecular sensors that enable neuronal detection of diverse environmental signals including thermal and mechanical stimuli, inflammatory mediators and tissue damage. Emerging evidence shows that sensory neurons participate in host-microbe interactions. Sensory neurons are able to detect pathogenic and commensal bacteria through specific metabolites, cell-wall components, and toxins. Here, we review recent work on the mechanisms of bacterial detection by distinct subtypes of gut-innervating sensory neurons. Upon activation, sensory neurons communicate to the immune system to modulate tissue inflammation through antidromic signalling and efferent neural circuits. We discuss how this neuro-immune regulation is orchestrated through transient receptor potential ion channels and sensory neuropeptides including substance P, calcitonin gene-related peptide, vasoactive intestinal peptide and pituitary adenylate cyclase-activating polypeptide. Recent studies also highlight a role for sensory neurons in regulating host defence against enteric bacterial pathogens including Salmonella typhimurium, Citrobacter rodentium and enterotoxigenic Escherichia coli. Understanding how sensory neurons respond to gastrointestinal flora and communicate with immune cells to regulate host defence enhances our knowledge of host physiology and may form the basis for new approaches to treat gastrointestinal diseases.

  16. Anosognosia as motivated unawareness: the 'defence' hypothesis revisited.

    PubMed

    Turnbull, Oliver H; Fotopoulou, Aikaterini; Solms, Mark

    2014-12-01

    Anosognosia for hemiplegia has seen a century of almost continuous research, yet a definitive understanding of its mechanism remains elusive. Essentially, anosognosic patients hold quasi-delusional beliefs about their paralysed limbs, in spite of all the contrary evidence, repeated questioning, and logical argument. We review a range of findings suggesting that emotion and motivation play an important role in anosognosia. We conclude that anosognosia involves (amongst other things) a process of psychological defence. This conclusion stems from a wide variety of clinical and experimental investigations, including data on implicit awareness of deficit, fluctuations in awareness over time, and dramatic effects upon awareness of psychological interventions such as psychotherapy, reframing of the emotional consequences of the paralysis, and first versus third person perspectival manipulations. In addition, we review and refute the (eight) arguments historically raised against the 'defence' hypothesis, including the claim that a defence-based account cannot explain the lateralised nature of the disorder. We argue that damage to a well-established right-lateralised emotion regulation system, with links to psychological processes that appear to underpin allocentric spatial cognition, plays a key role in anosognosia (at least in some patients). We conclude with a discussion of implications for clinical practice.

  17. Insects had it first: surfactants as a defence against predators

    PubMed Central

    Rostás, Michael; Blassmann, Katrin

    2008-01-01

    Insects have evolved an astonishing array of defences to ward off enemies. Well known and widespread is the regurgitation of oral secretion (OS), fluid that repels attacking predators. In herbivores, the effectiveness of OS has been ascribed so far to the presence of deterrent secondary metabolites sequestered from the host plant. This notion implies, however, that generalists experience less protection on plants with low amounts of secondary metabolites or with compounds ineffective against potential enemies. Resolving the dilemma, we describe a novel defence mechanism that is independent of deterrents as it relies on the intrinsic detergent properties of the OS. The OS of Spodoptera exigua (and other species) was found to be highly amphiphilic and well capable of wetting the hydrophobic cuticle of predatory ants. As a result, affected ants stopped attacking and engaged in extensive cleansing. The presence of surfactants was sufficient to explain the defensive character of herbivore OS. We hypothesize that detergency is a common but unrecognized mode of defence, which provides a base level of protection that may or may not be further enhanced by plant-derived deterrents. Our study also proves that insects ‘invented’ the use of defensive surfactants long before modern agriculture had started applying them as insecticides. PMID:18986976

  18. Effect of hypoxia and hypercapina on the airways defence reflexes.

    PubMed

    Tatár, M; Tarkanov, I A; Korpás, J; Kulik, A M

    1987-01-01

    In experiments on 10 adult anaesthetized cats (pentobarbital 30 mg.kg-1 i.p.) the effect of stimultaneous hypoxia and hypercapnia was studied on the defence respiratory reflexes of the airways. Expiratory reflex and cough were elicited by mechanical stimulation of the airways mucosa, and the obtained values were evaluated on basis of the intrapleural pressure. Inhalation of the hypoxic-hypercapnic gas mixture (11% + 7% CO2 in N2) for 15 minutes led to a significant decrease of respiratory frequency, tidal volume and PaCO2, while pHa and PaCO2 also decreased significantly together with the intensity of the expiratory reflex and that of cough. Recent studies, showed that in the course of the effect of hypoxia (11% O2) and of hypercapnia (5% CO2), cough intensity decreased, but the change was not significant. The decrease of the intensity of respiratory defence reflexes under hypoxic-hypercapnic conditions might have been due to the changes of centrally controlling structures, or to the effector part of the reflex arc, resulting from fatigue of the respiratory muscles. The possible effect of anaesthesia exerting a significant influence on the intensity and character of airways defence reflexes could not be excluded.

  19. Defence and security applications of quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Grasso, Robert J.

    2016-09-01

    Quantum Cascade Lasers (QCL) have seen tremendous recent application in the realm of Defence and Security. And, in many instances replacing traditional solid state lasers as the source of choice for Countermeasures, Remote Sensing, In-situ Sensing, Through-Barrier Sensing, and many others. Following their development and demonstration in the early 1990's, QCL's reached some maturity and specific defence and security application prior to 2005; with much initial development fostered by DARPA initiatives in the US, dstl, MoD, and EOARD funding initiatives in the UK, and University level R&D such as those by Prof Manijeh Razeghi at Northwestern University [1], and Prof Ted Masselink at Humboldt University [2]. As QCL's provide direct mid-IR laser output for electrical input, they demonstrate high quantum efficiency compared with diode pumped solid state lasers with optical parametric oscillators (OPOs) to generate mid-Infrared output. One particular advantage of QCL's is their very broad operational bandwidth, extending from the terahertz to the near-infrared spectral regions. Defence and Security areas benefiting from QCL's include: Countermeasures, Remote Sensing, Through-the-Wall Sensing, and Explosive Detection. All information used to construct this paper obtained from open sources.

  20. Chromatin assembly factor CAF-1 represses priming of plant defence response genes.

    PubMed

    Mozgová, Iva; Wildhaber, Thomas; Liu, Qinsong; Abou-Mansour, Eliane; L'Haridon, Floriane; Métraux, Jean-Pierre; Gruissem, Wilhelm; Hofius, Daniel; Hennig, Lars

    2015-09-01

    Plants have evolved efficient defence systems against pathogens that often rely on specific transcriptional responses. Priming is part of the defence syndrome, by establishing a hypersensitive state of defence genes such as after a first encounter with a pathogen. Because activation of defence responses has a fitness cost, priming must be tightly controlled to prevent spurious activation of defence. However, mechanisms that repress defence gene priming are poorly understood. Here, we show that the histone chaperone CAF-1 is required to establish a repressed chromatin state at defence genes. Absence of CAF-1 results in spurious activation of a salicylic acid-dependent pathogen defence response in plants grown under non-sterile conditions. Chromatin at defence response genes in CAF-1 mutants under non-inductive (sterile) conditions is marked by low nucleosome occupancy and high H3K4me3 at transcription start sites, resembling chromatin in primed wild-type plants. We conclude that CAF-1-mediated chromatin assembly prevents the establishment of a primed state that may under standard non-sterile growth conditions result in spurious activation of SA-dependent defence responses and consequential reduction of plant vigour.

  1. Cyanogenesis of wild lima bean (Phaseolus lunatus L.) is an efficient direct defence in nature.

    PubMed

    Ballhorn, Daniel J; Kautz, Stefanie; Heil, Martin; Hegeman, Adrian D

    2009-01-01

    In natural systems plants face a plethora of antagonists and thus have evolved multiple defence strategies. Lima bean (Phaseolus lunatus L.) is a model plant for studies of inducible indirect anti-herbivore defences including the production of volatile organic compounds (VOCs) and extrafloral nectar (EFN). In contrast, studies on direct chemical defence mechanisms as crucial components of lima beans' defence syndrome under natural conditions are nonexistent. In this study, we focus on the cyanogenic potential (HCNp; concentration of cyanogenic glycosides) as a crucial parameter determining lima beans' cyanogenesis, i.e. the release of toxic hydrogen cyanide from preformed precursors. Quantitative variability of cyanogenesis in a natural population of wild lima bean in Mexico was significantly correlated with missing leaf area. Since existing correlations do not by necessity mean causal associations, the function of cyanogenesis as efficient plant defence was subsequently analysed in feeding trials. We used natural chrysomelid herbivores and clonal lima beans with known cyanogenic features produced from field-grown mother plants. We show that in addition to extensively investigated indirect defences, cyanogenesis has to be considered as an important direct defensive trait affecting lima beans' overall defence in nature. Our results indicate the general importance of analysing 'multiple defence syndromes' rather than single defence mechanisms in future functional analyses of plant defences.

  2. Resurrection of an ancestral gene: functional and evolutionary analyses of the Ngrol genes transferred from Agrobacterium to Nicotiana.

    PubMed

    Aoki, Seishiro

    2004-08-01

    The Ng rol genes, which have high similarity in sequence to the rol genes of Agrobacterium rhizogenes, are present in the genome of untransformed plants of Nicotiana glauca. It is thought that bacterial infection resulted in the transfer of the Ng rol genes to plants early in the evolution of the genus Nicotiana, since several species in this genus contain rol-like sequences but others do not. Plants transformed with the bacterial rol genes exhibit various developmental and morphological changes. The presence of rol-like sequences in plant genomes is therefore thought to have contributed to the evolution of Nicotiana species. This paper focuses on studies of the Ng rol genes in present-day plants and during the evolution of the genus Nicotiana. The functional sequences of several Ng rol genes may have been conserved after their ancient introduction from a bacterium to the plant. Resurrection of an ancestral function of one of the Ng rol genes, as examined by physiological and evolutionary analyses, is also described. The origin of the Ng rol genes is then considered, based on results of molecular phylogenetic analyses. The effects of the horizontal transfer of the Ng rol genes and mutations in the genes are discussed on the plants of the genus Nicotiana during evolution.

  3. Hijacking common mycorrhizal networks for herbivore-induced defence signal transfer between tomato plants.

    PubMed

    Song, Yuan Yuan; Ye, Mao; Li, Chuanyou; He, Xinhua; Zhu-Salzman, Keyan; Wang, Rui Long; Su, Yi Juan; Luo, Shi Ming; Zeng, Ren Sen

    2014-01-28

    Common mycorrhizal networks (CMNs) link multiple plants together. We hypothesized that CMNs can serve as an underground conduit for transferring herbivore-induced defence signals. We established CMN between two tomato plants in pots with mycorrhizal fungus Funneliformis mosseae, challenged a 'donor' plant with caterpillar Spodoptera litura, and investigated defence responses and insect resistance in neighbouring CMN-connected 'receiver' plants. After CMN establishment caterpillar infestation on 'donor' plant led to increased insect resistance and activities of putative defensive enzymes, induction of defence-related genes and activation of jasmonate (JA) pathway in the 'receiver' plant. However, use of a JA biosynthesis defective mutant spr2 as 'donor' plants resulted in no induction of defence responses and no change in insect resistance in 'receiver' plants, suggesting that JA signalling is required for CMN-mediated interplant communication. These results indicate that plants are able to hijack CMNs for herbivore-induced defence signal transfer and interplant defence communication.

  4. Involvement of calcium/calmodulin signaling in cercosporin toxin biosynthesis by Cercospora nicotianae.

    PubMed

    Chung, Kuang-Ren

    2003-02-01

    Cercosporin is a non-host-selective, perylenequinone toxin produced by many phytopathogenic Cercospora species. The involvement of Ca(2+)/calmodulin (CaM) signaling in cercosporin biosynthesis was investigated by using pharmacological inhibitors. The results suggest that maintaining endogenous Ca(2+) homeostasis is required for cercosporin biosynthesis in Cercospora nicotianae. The addition of excess Ca(2+) to the medium slightly increased fungal growth but resulted in a reduction in cercosporin production. The addition of Ca(2+) chelators [EGTA and 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid] also reduced cercosporin production. Ca(2+) channel blockers exhibited a strong inhibition of cercosporin production only at higher concentrations (>2 mM). Cercosporin production was reduced greatly by Ca(2+) ionophores (A23187 and ionomycin) and internal Ca(2+) blocker [3,4,5-trimethoxybenzoic acid 8-(diethylamino)octyl ester]. Phospholipase C inhibitors (lithium, U73122, and neomycin) led to a concentration-dependent inhibition of cercosporin biosynthesis. Furthermore, the addition of CaM inhibitors (compound 48/80, trifluoperazine, W-7, and chlorpromazine) also markedly reduced cercosporin production. In contrast to W-7, W-5, with less specificity for CaM, led to only minor inhibition of cercosporin production. The inhibitory effects of Ca(2+)/CaM inhibitors were partially or completely reversed by the addition of external Ca(2+). As assessed with Fluo-3/AM (a fluorescent Ca(2+) indicator), the Ca(2+) content in the cytoplasm decreased significantly when fungal cultures were grown in a medium containing Ca(2+)/CaM antagonists, confirming the specificity of those Ca(2+)/CaM antagonists in C. nicotianae. Taken together, the results suggest that Ca(2+)/CaM signal transduction may play a pivotal role in cercosporin biosynthesis in C. nicotianae.

  5. L-Homoserylaminoethanol, a novel dipeptide alcohol inhibitor of eukaryotic DNA polymerase from a plant cultured cells, Nicotina tabacum L.

    PubMed

    Kuriyama, Isoko; Asano, Naoki; Kato, Ikuo; Oshige, Masahiko; Sugino, Akio; Kadota, Yasuhiro; Kuchitsu, Kazuyuki; Yoshida, Hiromi; Sakaguchi, Kengo; Mizushina, Yoshiyuki

    2004-03-01

    We found a novel inhibitor specific to eukaryotic DNA polymerase epsilon(pol epsilon) from plant cultured cells, Nicotina tabacum L. The compound (compound 1) was a dipeptide alcohol, L-homoserylaminoethanol. The 50% inhibition of pol epsilon activity by the compound was 43.6 microg/mL, and it had almost no effect on the activities of the other eukaryotic DNA polymerases such as alpha, beta, gamma and delta, prokaryotic DNA polymerases, nor DNA metabolic enzymes such as human telomerase, human immunodeficiency virus type 1 reverse transcriptase, T7 RNA polymerase, human DNA topoisomerase I and II, T4 polynucleotide kinase and bovine deoxyribonuclease I. Kinetic studies showed that inhibition of pol epsilon by the compound was non-competitive with respect to both template-primer DNA and nucleotide substrate. We succeeded in chemically synthesizing the stereoisomers, L-homoserylaminoethanol and D-homoserylaminoethanol, and found both were effective to the same extent. The IC(50) values of L- and D-homoserylaminoethanols for pol epsilon were 42.0 and 41.5 microg/mL, respectively. This represents the second discovery of a pol epsilon-specific inhibitor, and the first report on a water-soluble peptide-like compound as the inhibitor, which is required in biochemical studies of pol epsilon.

  6. Implementing Capability Based Planning within the Public Safety and Security Sector: Lessons from the Defence Experience

    DTIC Science & Technology

    2011-12-01

    Hales D Hales Consulting Dr. Paul Chouinard DRDC Centre for Security Science Defence R& D Canada – Centre for Security Science...Lessons from the Defence Experience Doug Hales D Hales Consulting Dr. Paul Chouinard DRDC Centre for Security Science Defence R& D Canada...CSS Technical Memorandum DRDC CSS TM 2011-26 December 2011 Principal Author Original signed by Doug Hales Doug Hales D

  7. Project Scheduling Tool for Maintaining Capability Interdependencies and Defence Program Investment: A User’s Guide

    DTIC Science & Technology

    2014-09-01

    UNCLASSIFIED Project Scheduling Tool for Maintaining Capability Interdependencies and Defence Program Investment: A User’s Guide M.-T. Nguyen Joint...product, the Project Scheduling Tool (version 1.4). The tool implements various mathematical Integer Linear Programming models, as well as an approach that...Scheduling Tool for Maintaining Capability Interdependencies and Defence Program Investment: A User’s Guide Executive Summary Defence decision-makers are faced

  8. Self-reported defence mechanisms as an outcome measure in psychotherapy: a study on the German version of the Defence Style Questionnaire DSQ 40.

    PubMed

    Schauenburg, Henning; Willenborg, Verena; Sammet, Isa; Ehrenthal, Johannes C

    2007-09-01

    The psychoanalytically informed construct of 'defence mechanisms' is of central importance for the understanding of the dynamics of inner conflicts and the onset of neurotic symptoms. Objective and valid assessment of 'defence' is difficult. There are a number of observer rating instruments but only few self-report questionnaires. The German version of the 'Defence Style Questionnaire - DSQ 40' (Andrews, Singh, & Bond, 1993) was examined with regard to its factorial and content validity, and its sensitivity to change during inpatient psychotherapy. One hundred and fifty-five patients with mixed diagnoses were administered the DSQ 40 and the SCL-90-R before and after 3 months of inpatient psychotherapy. Diagnoses were mostly affective and anxiety disorders as well as eating disorders, and there was a high comorbidity of personality disorders. After deletion of some items due to insufficient pairwise item-intercorrelation or false classification to a defence mechanism by experienced clinicians, we found three stable factors of defence (maladaptive, intermediate-neurotic and adaptive) consistent with the previous research. After 3 months of therapy, a decrease in maladaptive mechanisms and an increase in adaptive patterns were found, while neurotic mechanisms did not change on average. Our shortened version of the DSQ 40 was shown to be a valid instrument for the assessment of defence mechanisms and change in these mechanisms after psychotherapy. Our design did not permit an assessment of whether or not the change in defence mechanisms was due to the therapeutic treatment.

  9. Introducing 'The Diverse Nature of Defence Healthcare' university module for DMS personnel.

    PubMed

    Carter, Chris; Blake, L

    2015-12-01

    Over the past 10 years the UK Defence Medical Services has deployed healthcare personnel to a variety of operational areas in support of UK Operations. The unique nature of every operational deployment, in conjunction with the wide variety of roles which healthcare staff undertake, necessitates bespoke educational preparation of the military healthcare force. This paper explores the creation and development of one of the four modules which comprise the BSc (Hons) in Defence Health Care studies, entitled 'The Diverse Nature of Defence Healthcare'. It demonstrates the unique contribution that the Defence School of Healthcare Education makes towards Generation and Preparation of the Force for deployment.

  10. Anti-predator defence and the complexity-stability relationship of food webs.

    PubMed

    Kondoh, Michio

    2007-07-07

    The mechanism for maintaining complex food webs has been a central issue in ecology because theory often predicts that complexity (higher the species richness, more the interactions) destabilizes food webs. Although it has been proposed that prey anti-predator defence may affect the stability of prey-predator dynamics, such studies assumed a limited and relatively simpler variation in the food-web structure. Here, using mathematical models, I report that food-web flexibility arising from prey anti-predator defence enhances community-level stability (community persistence and robustness) in more complex systems and even changes the complexity-stability relationship. The model analysis shows that adaptive predator-specific defence enhances community-level stability under a wide range of food-web complexity levels and topologies, while generalized defence does not. Furthermore, while increasing food-web complexity has minor or negative effects on community-level stability in the absence of defence adaptation, or in the presence of generalized defence, in the presence of predator-specific defence, the connectance-stability relationship may become unimodal. Increasing species richness, in contrast, always lowers community-level stability. The emergence of a positive connectance-stability relationship however necessitates food-web compartmentalization, high defence efficiency and low defence cost, suggesting that it only occurs under a restricted condition.

  11. Identification of plant defence regulators through transcriptional profiling of Arabidopsis thaliana cdd1 mutant.

    PubMed

    Swain, Swadhin; Singh, Nidhi; Nandi, Ashis Kumar

    2015-03-01

    A sustainable balance between defence and growth is essential for optimal fitness under pathogen stress. Plants activate immune response at the cost of normal metabolic requirements. Thus, plants that constitutively activate defence are deprived of growth. Arabidopsis thaliana mutant constitutive defence without defect in growth and development1 (cdd1) is an exception. The cdd1 mutant is constitutive for salicylic acid accumulation, signalling, and defence against biotrophic and hemibiotrophic pathogens, without having much impact on growth. Thus, cdd1 offers an ideal genetic background to identify novel regulators of plant defence. Here we report the differential gene expression profile between cdd1 and wild-type plants as obtained by microarray hybridization. Expression of several defence-related genes also supports constitutive activation of defence in cdd1. We screened T-DNA insertion mutant lines of selected genes, for resistance against virulent bacterial pathogen Pseudomonas syringae pv. tomato DC3000 (Pst DC3000). Through bacterial resistance, callose deposition and pathogenesis-associated expression analyses, we identified four novel regulators of plant defence. Resistance levels in the mutants suggest that At2g19810 and [rom] At5g05790 are positive regulators, whereas At1g61370 and At3g42790 are negative regulators of plant defence against bacterial pathogens.

  12. Costs and benefits of chemical defence in the Red Alga Bonnemaisonia hamifera.

    PubMed

    Nylund, Göran M; Enge, Swantje; Pavia, Henrik

    2013-01-01

    A number of studies have shown that the production of chemical defences is costly in terrestrial vascular plants. However, these studies do not necessarily reflect the costs of defence production in macroalgae, due to structural and functional differences between vascular plants and macroalgae. Using a specific culturing technique, we experimentally manipulated the defence production in the red alga Bonnemaisonia hamifera to examine if the defence is costly in terms of growth. Furthermore, we tested if the defence provides fitness benefits by reducing harmful bacterial colonisation of the alga. Costly defences should provide benefits to the producer in order to be maintained in natural populations, but such benefits through protection against harmful bacterial colonisation have rarely been documented in macroalgae. We found that algae with experimentally impaired defence production, but with an externally controlled epibacterial load, grew significantly better than algae with normal defence production. We also found that undefended algae exposed to a natural epibacterial load experienced a substantial reduction in growth and a 6-fold increase in cell bleaching, compared to controls. Thus, this study provides experimental evidence that chemical defence production in macroalgae is costly, but that the cost is outweighed by fitness benefits provided through protection against harmful bacterial colonisation.

  13. Programmed cell death as a defence against infection.

    PubMed

    Jorgensen, Ine; Rayamajhi, Manira; Miao, Edward A

    2017-03-01

    Eukaryotic cells can die from physical trauma, which results in necrosis. Alternatively, they can die through programmed cell death upon the stimulation of specific signalling pathways. In this Review, we discuss the role of different cell death pathways in innate immune defence against bacterial and viral infection: apoptosis, necroptosis, pyroptosis and NETosis. We describe the interactions that interweave different programmed cell death pathways, which create complex signalling networks that cross-guard each other in the evolutionary 'arms race' with pathogens. Finally, we describe how the resulting cell corpses - apoptotic bodies, pore-induced intracellular traps (PITs) and neutrophil extracellular traps (NETs) - promote the clearance of infection.

  14. Neutrophils: Between Host Defence, Immune Modulation, and Tissue Injury

    PubMed Central

    Kruger, Philipp; Saffarzadeh, Mona; Weber, Alexander N. R.; Rieber, Nikolaus; Radsak, Markus; von Bernuth, Horst; Benarafa, Charaf; Roos, Dirk; Skokowa, Julia; Hartl, Dominik

    2015-01-01

    Neutrophils, the most abundant human immune cells, are rapidly recruited to sites of infection, where they fulfill their life-saving antimicrobial functions. While traditionally regarded as short-lived phagocytes, recent findings on long-term survival, neutrophil extracellular trap (NET) formation, heterogeneity and plasticity, suppressive functions, and tissue injury have expanded our understanding of their diverse role in infection and inflammation. This review summarises our current understanding of neutrophils in host-pathogen interactions and disease involvement, illustrating the versatility and plasticity of the neutrophil, moving between host defence, immune modulation, and tissue damage. PMID:25764063

  15. Bacterial self-defence: how Escherichia coli evades serum killing.

    PubMed

    Miajlovic, Helen; Smith, Stephen G

    2014-05-01

    The ability to survive the bactericidal action of serum is advantageous to extraintestinal pathogenic Escherichia coli that gain access to the bloodstream. Evasion of the innate defences present in serum, including complement and antimicrobial peptides, involves multiple factors. Serum resistance mechanisms utilized by E. coli include the production of protective extracellular polysaccharide capsules and expression of factors that inhibit or interfere with the complement cascade. Recent studies have also highlighted the importance of structural integrity of the cell envelope in serum survival. These survival strategies are outlined in this review with particular attention to novel findings and recent insights into well-established resistance mechanisms.

  16. Interspecific assistance: fiddler crabs help heterospecific neighbours in territory defence.

    PubMed

    Booksmythe, Isobel; Jennions, Michael D; Backwell, Patricia R Y

    2010-12-23

    Theory predicts that territory owners will help established neighbours to repel intruders, when doing so is less costly than renegotiating boundaries with successful usurpers of neighbouring territories. Here, we show for the first time, to our knowledge, cooperative territory defence between heterospecific male neighbours in the fiddler crabs Uca elegans and Uca mjoebergi. We show experimentally that resident U. elegans were equally likely to help a smaller U. mjoebergi or U. elegans neighbour during simulated intrusions by intermediate sized U. elegans males (50% of cases for both). Helping was, however, significantly less likely to occur when the intruder was a U. mjoebergi male (only 15% of cases).

  17. Doctors' attitudes on civil defence and nuclear weapon issues.

    PubMed

    Hunter-Brown, I H

    1989-01-01

    97 out of 219 doctors responded to a questionnaire on medical aspects of nuclear weapons. A majority of the respondents considered that the then-current civil defence planning was not a valuable use of National Health Service resources, and that an attack with nuclear weapons would cause a degree of suffering beyond the profession's capacity to treat; thought doctors should have a special voice on nuclear issues; and believed Britain should not be increasing its nuclear weapons, and that if expenditure on them were reduced, the savings should go on health. The high support for organizations like MAPW was gratifying.

  18. Analysis of direct punch velocity in professional defence

    NASA Astrophysics Data System (ADS)

    Lapkova, Dora; Adamek, Milan

    2016-06-01

    This paper is focused on analysis of a direct punch. Nowadays, professional defence is basic part of effective protection of people and property. There are many striking techniques and the goal of this research was to analyze the direct punch. The analysis is aimed to measure the velocity with help of high speed camera Olympus i-Speed 2 and then find the dependences of this velocity on input parameters. For data analysis two pieces of software were used - i-Speed Control Software and MINITAB. 111 participants took part in this experiment. The results are presented in this paper - especially dependence of mean velocity on time and difference in velocity between genders.

  19. Overexpression of Citrus junos mitochondrial citrate synthase gene in Nicotiana benthamiana confers aluminum tolerance.

    PubMed

    Deng, Wei; Luo, Keming; Li, Zhengguo; Yang, Yingwu; Hu, Nan; Wu, Yu

    2009-07-01

    Aluminum (Al) toxicity is one of the major factors that limit plant growth in acid soils. Al-induced release of organic acids into rhizosphere from the root apex has been identified as a major Al-tolerance mechanism in many plant species. In this study, Al tolerance of Yuzu (Citrus Junos Sieb. ex Tanaka) was tested on the basis of root elongation and the results demonstrated that Yuzu was Al tolerant compared with other plant species. Exposure to Al triggered the exudation of citrate from the Yuzu root. Thus, the mechanism of Al tolerance in Yuzu involved an Al-inducible increase in citrate release. Aluminum also elicited an increase of citrate content and increased the expression level of mitochondrial citrate synthase (CjCS) gene and enzyme activity in Yuzu. The CjCS gene was cloned from Yuzu and overexpressed in Nicotiana benthamiana using Agrobacterium tumefaciens-mediated methods. Increased expression level of the CjCS gene and enhanced enzyme activity were observed in transgenic plants compared with the wild-type plants. Root growth experiments showed that transgenic plants have enhanced levels of Al tolerance. The transgenic Nicotiana plants showed increased levels of citrate in roots compared to wild-type plants. The exudation of citrate from roots of the transgenic plants significantly increased when exposed to Al. The results with transgenic plants suggest that overexpression of mitochondrial CS can be a useful tool to achieve Al tolerance.

  20. Gene-specific disruption in the filamentous fungus Cercospora nicotianae using a split-marker approach.

    PubMed

    You, Bang-Jau; Lee, Miin-Huey; Chung, Kuang-Ren

    2009-07-01

    To determine if DNA configuration, gene locus, and flanking sequences will affect homologous recombination in the phytopathogenic fungus Cercospora nicotianae, we evaluated and compared disruption efficiency targeting four cercosporin toxin biosynthetic genes encoding a polyketide synthase (CTB1), a monooxygenase/O-methyltransferase (CTB3), a NADPH-dependent oxidoreductase (CTB5), and a FAD/FMN-dependent oxidoreductase (CTB7). Transformation of C. nicotianae using a circular plasmid resulted in low disruption frequency. The use of endonucleases or a selectable marker DNA fragment flanked by homologous sequence either at one end or at both ends in the transformation procedures, increased disruption efficiency in some but not all CTB genes. A split-marker approach, using two DNA fragments overlapping within the selectable marker, increased the frequency of targeted gene disruption and homologous integration as high as 50%, depending on the target gene and on the length of homologous DNA sequence flanking the selectable marker. The results indicate that the split-marker approach favorably decreased ectopic integration and thus, greatly facilitated targeted gene disruption in this important fungal pathogen.

  1. Evolutionary time-scale of the begomoviruses: evidence from integrated sequences in the Nicotiana genome.

    PubMed

    Lefeuvre, Pierre; Harkins, Gordon W; Lett, Jean-Michel; Briddon, Rob W; Chase, Mark W; Moury, Benoit; Martin, Darren P

    2011-01-01

    Despite having single stranded DNA genomes that are replicated by host DNA polymerases, viruses in the family Geminiviridae are apparently evolving as rapidly as some RNA viruses. The observed substitution rates of geminiviruses in the genera Begomovirus and Mastrevirus are so high that the entire family could conceivably have originated less than a million years ago (MYA). However, the existence of geminivirus related DNA (GRD) integrated within the genomes of various Nicotiana species suggests that the geminiviruses probably originated >10 MYA. Some have even suggested that a distinct New-World (NW) lineage of begomoviruses may have arisen following the separation by continental drift of African and American proto-begomoviruses ∼110 MYA. We evaluate these various geminivirus origin hypotheses using Bayesian coalescent-based approaches to date firstly the Nicotiana GRD integration events, and then the divergence of the NW and Old-World (OW) begomoviruses. Besides rejecting the possibility of a<2 MYA OW-NW begomovirus split, we could also discount that it may have occurred concomitantly with the breakup of Gondwanaland 110 MYA. Although we could only confidently narrow the date of the split down to between 2 and 80 MYA, the most plausible (and best supported) date for the split is between 20 and 30 MYA--a time when global cooling ended the dispersal of temperate species between Asia and North America via the Beringian land bridge.

  2. The cuticle: Not only a barrier for plant defence: A novel defence syndrome in plants with cuticular defects.

    PubMed

    Chassot, Céline; Nawrath, Christiane; Métraux, Jean-Pierre

    2008-02-01

    The cuticle is a physical barrier that prevents water loss and protects against irradiation, xenobiotics and pathogens. This classic textbook statement has recently been revisited and several observations were made showing that this dogma falls short of being universally true. Both transgenic Arabidopsis thaliana lines expressing cell wall-targeted fungal cutinase (so-called CUTE plants) or lipase as well as several A. thaliana mutants with altered cuticular structure remained free of symptoms after an inoculation with Botrytis cinerea. The alterations in cuticular structure lead to the release of fungitoxic substances and changes in gene expression that form a multifactorial defence response. Several models to explain this syndrome are discussed.

  3. Manic Defences in Contemporary Society. The Psychocultural Approach.

    PubMed

    Rudan, Dusko; Jakovljevic, Miro; Marcinko, Darko

    2016-12-01

    The article discusses the impact of contemporary culture on the individual's personality. We used the "psychocultural" approach whose key feature is the amalgamation of theories and methods belonging to psychodynamic and psychosocial studies, as well as those used in the field of media and cultural studies. The idea of a potentially therapeutic effect of culture (therapy culture) can already been seen in Freud's and Lacan's texts, and it is often used in critical analyses of contemporary corporate culture, which is more or less developed in some parts of the world. In their criticisms, many contemporary authors emphasize that modern societies have a tendency towards the weakening of basic commitment, or lack thereof, to a social equivalent of Winnicott's concept of environmental provisions as an inalienable democratic right essential for human emotional and mental progress or emotional well-being. The article describes frequent resorting to the so-called manic defences that defensively distort, deny and obscure the awareness that a human being is not the omnipotent source of life, but instead depends on other human beings, and often tries to compensate for loss through various activities. The article describes excessive shopping as an activity that often serves as an attempt to find what was lost, i.e. to fill an emotional void. This solution (resorting to manic defences) is encouraged by contemporary culture, especially through promotional material (e.g. advertising). The main theses of this article are supported by quotations and data from world literature.

  4. Microstructured fibres: a positive impact on defence technology?

    NASA Astrophysics Data System (ADS)

    O'Driscoll, E. J.; Watson, M. A.; Delmonte, T.; Petrovich, M. N.; Feng, X.; Flanagan, J. C.; Hayes, J. R.; Richardson, D. J.

    2006-09-01

    In this paper we seek to assess the potential impact of microstructured fibres for security and defence applications. Recent literature has presented results on using microstructured fibre for delivery of high power, high quality radiation and also on the use of microstructured fibre for broadband source generation. Whilst these two applications may appear contradictory to one another the inherent design flexibility of microstructured fibres allows fibres to be fabricated for the specific application requirements, either minimising (for delivery) or maximising (for broadband source generation) the nonlinear effects. In platform based laser applications such as infrared counter measures, remote sensing and laser directed-energy weapons, a suitable delivery fibre providing high power, high quality light delivery would allow a laser to be sited remotely from the sensor/device head. This opens up the possibility of several sensor/device types sharing the same multi-functional laser, thus reducing the complexity and hence the cost of such systems. For applications requiring broadband source characteristics, microstructured fibres can also offer advantages over conventional sources. By exploiting the nonlinear effects it is possible to realise a multifunctional source for applications such as active hyperspectral imaging, countermeasures, and biochemical sensing. These recent results suggest enormous potential for these novel fibre types to influence the next generation of photonic systems for security and defence applications. However, it is important to establish where the fibres can offer the greatest advantages and what research still needs to be done to drive the technology towards real platform solutions.

  5. Photosynthesis, photorespiration, and light signalling in defence responses.

    PubMed

    Kangasjärvi, Saijaliisa; Neukermans, Jenny; Li, Shengchun; Aro, Eva-Mari; Noctor, Graham

    2012-02-01

    Visible light is the basic energetic driver of plant biomass production through photosynthesis. The constantly fluctuating availability of light and other environmental factors means that the photosynthetic apparatus must be able to operate in a dynamic fashion appropriate to the prevailing conditions. Dynamic regulation is achieved through an array of homeostatic control mechanisms that both respond to and influence cellular energy and reductant status. In addition, light availability and quality are continuously monitored by plants through photoreceptors. Outside the laboratory growth room, it is within the context of complex changes in energy and signalling status that plants must regulate pathways to deal with biotic challenges, and this can be influenced by changes in the highly energetic photosynthetic pathways and in the turnover of the photosynthetic machinery. Because of this, defence responses are neither simple nor easily predictable, but rather conditioned by the nutritional and signalling status of the plant cell. This review discusses recent data and emerging concepts of how recognized defence pathways interact with and are influenced by light-dependent processes. Particular emphasis is placed on the potential roles of the chloroplast, photorespiration, and photoreceptor-associated pathways in regulating the outcome of interactions between plants and pathogenic organisms.

  6. Persistence of bat defence reactions in high Arctic moths (Lepidoptera).

    PubMed

    Rydell, J; Roininen, H; Philip, K W

    2000-03-22

    We investigated the bat defence reactions of three species of moths (Gynaephora groenlandica, Gynaephora rossi (Lymantriidae) and Psychophora sabini (Geometridae)) in the Canadian Arctic archipelago. Since these moths inhabit the Arctic tundra and, therefore, are most probably spatially isolated from bats, their hearing and associated defensive reactions are probably useless and would therefore be expected to disappear with ongoing adaptation to Arctic conditions. When exposed to bat-like ultrasound (26 kHz and 110 dB sound pressure level root mean square at 1 m) flying male Gynaephora spp. always reacted defensively by rapidly reversing their flight course. They could hear the sound and reacted at least 15-25 m away. Psychophora sabini walking on a surface froze at distances of at least 5-7 m from the sound source. However, two out of three individuals of this species (all males) did not respond in any way to the sound while in flight. Hence, we found evidence of degeneration of bat defence reactions, i.e. adaptation to the bat-free environment, in P. sabini but not in Gynaephora spp. Some Arctic moths (Gynaephora spp.) still possess defensive reactions against bats, possibly because the selection pressure for the loss of the trait is such that it declines only very slowly (perhaps by genetic drift; and there may not have been enough time for the trait to disappear. One possible reason may be that Arctic moths have long generation times.

  7. Mutualistic ants as an indirect defence against leaf pathogens.

    PubMed

    González-Teuber, Marcia; Kaltenpoth, Martin; Boland, Wilhelm

    2014-04-01

    Mutualistic ants are commonly considered as an efficient indirect defence against herbivores. Nevertheless, their indirect protective role against plant pathogens has been scarcely investigated. We compared the protective role against pathogens of two different ant partners, a mutualistic and a parasitic ant, on the host plant Acacia hindsii (Fabaceae). The epiphytic bacterial community on leaves was evaluated in the presence and absence of both ant partners by cultivation and by 454 pyrosequencing of the 16S rRNA gene. Pathogen-inflicted leaf damage, epiphytic bacterial abundance (colony-forming units) and number of operational taxonomic units (OTUs) were significantly higher in plants inhabited by parasitic ants than in plants inhabited by mutualistic ants. Unifrac unweighted and weighted principal component analyses showed that the bacterial community composition on leaves changed significantly when mutualistic ants were removed from plants or when plants were inhabited by parasitic ants. Direct mechanisms provided by ant-associated bacteria would contribute to the protective role against pathogens. The results suggest that the indirect defence of mutualistic ants also covers the protection from bacterial plant pathogens. Our findings highlight the importance of considering bacterial partners in ant-plant defensive mutualisms, which can contribute significantly to ant-mediated protection from plant pathogens.

  8. Effects of light on direct and indirect defences against herbivores of young plants of Mallotus japonicus demonstrate a trade-off between two indirect defence traits

    PubMed Central

    Yamawo, Akira; Hada, Yoshio

    2010-01-01

    Background and Aims Although most studies on plant defence strategies have focused on a particular defence trait, some plant species develop multiple defence traits. To clarify the effects of light on the development of multiple defence traits, the production of direct and indirect defence traits of young plants of Mallotus japonicus were examined experimentally under different light conditions. Methods The young plants were cultivated under three light conditions in the experimental field for 3 months from May to July. Numbers of ants and pearl bodies on leaves in July were examined. After cultivation, the plants were collected and the developments of trichomes and pellucid dots, and extrafloral nectaries (EFNs) on the leaves were examined. On plants without nectar-collecting insects, the size of EFNs and the volume of extrafloral nectar secreted from the EFNs were examined. Key results Densities of trichomes and pellucid dots did not differ significantly among the plants under the different light conditions, suggesting that the chemical and physical defences function under both high and low light availability. The number of EFNs on the leaves did not differ significantly among the plants under the different light conditions, but there appeared to be a trade-off between the size of EFNs and the number of pearl bodies; the largest EFNs and the smallest number of pearl bodies were found under high light availability. EFN size was significantly correlated with the volume of extrafloral nectar secreted for 24 h. The number of ants on the plants was smaller under low light availability than under high and moderate light availability. Conclusions These results suggest that direct defence traits function regardless of light conditions, but light conditions affected the development of indirect defence traits. PMID:20472698

  9. Estimating the ROI for Recruitment Marketing and Advertising Expenditure for the Australian Defence Force

    DTIC Science & Technology

    2012-03-01

    OF RECRUITMENT MARKETING AND ADVERTISING EXPENDITURE FOR THE AUSTRALIAN DEFENCE FORCE by Christopher D. Kitchin March 2012 Thesis...ROI for Recruitment Marketing and Advertising Expenditure for the Australian Defence Force 5. FUNDING NUMBERS 6. AUTHOR(S) Christopher D. Kitchin... advertising expenditure was found to have no effect on enlistments. 14. SUBJECT TERMS Marketing and Advertising Expenditure, Recruitment 15

  10. UK Defence Acquisition Process for NEC: Transaction Governance within an Integrated Project Team

    DTIC Science & Technology

    2009-04-22

    Government of Margaret Thatcher . Of the five largest defence companies in 1979, four were state owned: British Aerospace, British Shipbuilders, Royal...NEC demands a more collaborative, through- life approach to defence acquisition. 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: 17. LIMITATION...Innovative Systems Engineering), exploring organisational aspects of Through Life Systems Management. Maytorena became a lecturer in Construction Project

  11. To Gain the Academic Capital: The Conflict and Solution in the Dissertation Proposal Defence

    ERIC Educational Resources Information Center

    Ningning, Zhao

    2006-01-01

    Doctor candidates get the academic identity and academic capital in his field by the thesis writing. The dissertation proposal defence hold on the public field promotes the state of academic and legalizes the discipline of the academic community. During the dissertation proposal defence, doctor candidates may face three conflicts. The first is…

  12. The effect of energy reserves and food availability on optimal immune defence.

    PubMed

    Houston, Alasdair I; McNamara, John M; Barta, Zoltán; Klasing, Kirk C

    2007-11-22

    In order to avoid both starvation and disease, animals must allocate resources between energy reserves and immune defence. We investigate the optimal allocation. We find that animals with low reserves choose to allocate less to defence than animals with higher reserves because when reserves are low it is more important to increase reserves to reduce the risk of starvation in the future. In general, investment in immune defence increases monotonically with energy reserves. An exception is when the animal can reduce its probability of death from disease by reducing its foraging rate. In this case, allocation to immune defence can peak at intermediate reserves. When food changes over time, the optimal response depends on the frequency of changes. If the environment is relatively stable, animals forage most intensively when the food is scarce and invest more in immune defence when the food is abundant than when it is scarce. If the environment changes quickly, animals forage at low intensity when the food is scarce, but at high intensity when the food is abundant. As the rate of environmental change increases, immune defence becomes less dependent on food availability. We show that the strength of selection on reserve-dependent immune defence depends on how foraging intensity and immune defence determine the probability of death from disease.

  13. An Exploratory Study of the Defence Mechanisms Used in Psychotherapy by Adults Who Have Intellectual Disabilities

    ERIC Educational Resources Information Center

    Newman, D. W.; Beail, N.

    2010-01-01

    Problem: A significant concept in psychodynamic theory and practice is that of defence mechanisms. The identifications of defences is a key task of the therapist and these are then used in the formulation and form part of the therapist's interventions. Case studies of psychotherapy with adults who have intellectual disabilities (IDs) suggest that…

  14. The effect of energy reserves and food availability on optimal immune defence

    PubMed Central

    Houston, Alasdair I; McNamara, John M; Barta, Zoltán; Klasing, Kirk C

    2007-01-01

    In order to avoid both starvation and disease, animals must allocate resources between energy reserves and immune defence. We investigate the optimal allocation. We find that animals with low reserves choose to allocate less to defence than animals with higher reserves because when reserves are low it is more important to increase reserves to reduce the risk of starvation in the future. In general, investment in immune defence increases monotonically with energy reserves. An exception is when the animal can reduce its probability of death from disease by reducing its foraging rate. In this case, allocation to immune defence can peak at intermediate reserves. When food changes over time, the optimal response depends on the frequency of changes. If the environment is relatively stable, animals forage most intensively when the food is scarce and invest more in immune defence when the food is abundant than when it is scarce. If the environment changes quickly, animals forage at low intensity when the food is scarce, but at high intensity when the food is abundant. As the rate of environmental change increases, immune defence becomes less dependent on food availability. We show that the strength of selection on reserve-dependent immune defence depends on how foraging intensity and immune defence determine the probability of death from disease. PMID:17848371

  15. Negative regulation of defence and stress genes by EAR-motif-containing repressors.

    PubMed

    Kazan, Kemal

    2006-03-01

    Although positive control or activation mechanism(s) involved in plant defence- and stress-related gene expression is relatively well studied, little is known about what keeps defensive armoury under control when not needed. Recent reports suggest that transcriptional repression of gene expression by EAR-motif-containing repressor proteins plays a key role in modulating plant defence and stress responses.

  16. [TMV-infection localization and development of induced virus resistance in Nicotiana sanderae Hort., Datura stramonium L. and Datura metel].

    PubMed

    Kovalenko, O H; Kyrychenko, A M

    2004-01-01

    The localization of virus infection and development of local and systemic induced resistance in plants Nicotiana sanderae Hort., Datura stramonium L. and D. metel L. infected by TMV have been studied. It was shown that acquired resistance to the second infection is induced in hypersensitive plants infected by TMV independent of localization mechanism. No definite correlation exists between these defense reactions.

  17. Chronic ozone exacerbates the reduction in photosynthesis and acceleration of senescence caused by limited N availability in Nicotiana sylvestris

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Elevated ozone (O3) and limiting soil nitrogen (N) availability both negatively affect crop performance. However, little is known about how the combination of elevated O3 and limiting N affect crop growth and metabolism. In this study, we grew tobacco (Nicotiana sylvestris) in ambient and elevated O...

  18. Induced defences alter the strength and direction of natural selection on reproductive traits in common milkweed.

    PubMed

    Thompson, K A; Cory, K A; Johnson, M T J

    2017-01-30

    Evolutionary biologists have long sought to understand the ecological processes that generate plant reproductive diversity. Recent evidence indicates that constitutive antiherbivore defences can alter natural selection on reproductive traits, but it is unclear whether induced defences will have the same effect and whether reduced foliar damage in defended plants is the cause of this pattern. In a factorial field experiment using common milkweed, Asclepias syriaca L., we induced plant defences using jasmonic acid (JA) and imposed foliar damage using scissors. We found that JA-induced plants experienced selection for more inflorescences that were smaller in size (fewer flowers), whereas control plants only experienced a trend towards selection for larger inflorescences (more flowers); all effects were independent of foliar damage. Our results demonstrate that induced defences can alter both the strength and direction of selection on reproductive traits, and suggest that antiherbivore defences may promote the evolution of plant reproductive diversity.

  19. Simple growth patterns can create complex trajectories for the ontogeny of constitutive chemical defences in seaweeds.

    PubMed

    Paul, Nicholas A; Svensson, Carl Johan; de Nys, Rocky; Steinberg, Peter D

    2014-01-01

    All of the theory and most of the data on the ecology and evolution of chemical defences derive from terrestrial plants, which have considerable capacity for internal movement of resources. In contrast, most macroalgae--seaweeds--have no or very limited capacity for resource translocation, meaning that trade-offs between growth and defence, for example, should be localised rather than systemic. This may change the predictions of chemical defence theories for seaweeds. We developed a model that mimicked the simple growth pattern of the red seaweed Asparagopsis armata which is composed of repeating clusters of somatic cells and cells which contain deterrent secondary chemicals (gland cells). To do this we created a distinct growth curve for the somatic cells and another for the gland cells using empirical data. The somatic growth function was linked to the growth function for defence via differential equations modelling, which effectively generated a trade-off between growth and defence as these neighbouring cells develop. By treating growth and defence as separate functions we were also able to model a trade-off in growth of 2-3% under most circumstances. However, we found contrasting evidence for this trade-off in the empirical relationships between growth and defence, depending on the light level under which the alga was cultured. After developing a model that incorporated both branching and cell division rates, we formally demonstrated that positive correlations between growth and defence are predicted in many circumstances and also that allocation costs, if they exist, will be constrained by the intrinsic growth patterns of the seaweed. Growth patterns could therefore explain contrasting evidence for cost of constitutive chemical defence in many studies, highlighting the need to consider the fundamental biology and ontogeny of organisms when assessing the allocation theories for defence.

  20. Differential phenotypic and genetic expression of defence compounds in a plant-herbivore interaction along elevation.

    PubMed

    Salgado, Ana L; Suchan, Tomasz; Pellissier, Loïc; Rasmann, Sergio; Ducrest, Anne-Lyse; Alvarez, Nadir

    2016-09-01

    Elevation gradients impose large differences in abiotic and biotic conditions over short distances, in turn, likely driving differences in gene expression more than would genetic variation per se, as natural selection and drift are less likely to fix alleles at such a narrow spatial scale. As elevation increases, the pressure exerted on plants by herbivores and on arthropod herbivores by predators decreases, and organisms spanning the elevation gradient are thus expected to show lower levels of defence at high elevation. The alternative hypothesis, based on the optimal defence theory, is that defence allocation should be higher in low-resource habitats such as those at high elevation, due to higher costs associated with tissue replacement. In this study, we analyse variation with elevation in (i) defence compound content in the plant Lotus corniculatus and (ii) gene expression associated with defence against predators in the specific phytophagous moth, Zygaena filipendulae. Both species produce cyanogenic glycosides (CNglcs) such as lotaustralin and linamarin as defence mechanisms, with the moth, in addition, being able to sequester CNglcs from its host plant. Specifically, we tested the assumption that the defence-associated phenotype in plants and the gene expression in the insect herbivore should covary between low- and high-elevation environments. We found that L. corniculatus accumulated more CNglcs at high elevation, a result in agreement with the optimal defence theory. By contrast, we found that the levels of expression in the defence genes of Z. filipendulae larvae were not related to the CNglc content of their host plant. Overall, expression levels were not correlated with elevation either, with the exception of the UGT33A1 gene, which showed a marginally significant trend towards higher expression at high elevation when using a simple statistical framework. These results suggest that the defence phenotype of plants against herbivores, and subsequent

  1. Differential phenotypic and genetic expression of defence compounds in a plant–herbivore interaction along elevation

    PubMed Central

    Salgado, Ana L.; Suchan, Tomasz; Pellissier, Loïc; Rasmann, Sergio; Ducrest, Anne-Lyse

    2016-01-01

    Elevation gradients impose large differences in abiotic and biotic conditions over short distances, in turn, likely driving differences in gene expression more than would genetic variation per se, as natural selection and drift are less likely to fix alleles at such a narrow spatial scale. As elevation increases, the pressure exerted on plants by herbivores and on arthropod herbivores by predators decreases, and organisms spanning the elevation gradient are thus expected to show lower levels of defence at high elevation. The alternative hypothesis, based on the optimal defence theory, is that defence allocation should be higher in low-resource habitats such as those at high elevation, due to higher costs associated with tissue replacement. In this study, we analyse variation with elevation in (i) defence compound content in the plant Lotus corniculatus and (ii) gene expression associated with defence against predators in the specific phytophagous moth, Zygaena filipendulae. Both species produce cyanogenic glycosides (CNglcs) such as lotaustralin and linamarin as defence mechanisms, with the moth, in addition, being able to sequester CNglcs from its host plant. Specifically, we tested the assumption that the defence-associated phenotype in plants and the gene expression in the insect herbivore should covary between low- and high-elevation environments. We found that L. corniculatus accumulated more CNglcs at high elevation, a result in agreement with the optimal defence theory. By contrast, we found that the levels of expression in the defence genes of Z. filipendulae larvae were not related to the CNglc content of their host plant. Overall, expression levels were not correlated with elevation either, with the exception of the UGT33A1 gene, which showed a marginally significant trend towards higher expression at high elevation when using a simple statistical framework. These results suggest that the defence phenotype of plants against herbivores, and subsequent

  2. In vitro cytotoxicity of Nicotiana gossei leaves, used in the Australian Aboriginal smokeless tobacco known as pituri or mingkulpa.

    PubMed

    Moghbel, Nahid; Ryu, BoMi; Cabot, Peter J; Steadman, Kathryn J

    2016-07-08

    The Aboriginal population of Central Australia use endemic Nicotiana species to make a smokeless tobacco product known usually as pituri or mingkulpa. Nicotiana leaves are masticated with wood ash into a 'quid' that is chewed/sucked for absorption of nicotine. In addition to nicotine, smokeless tobacco products contain a spectrum of biologically active compounds that may contribute to effects on health. The objective of this study was to quantify nicotine, and related alkaloids and tobacco specific nitrosamines (TSNAs), in Nicotiana leaves used in pituri, and compare in vitro toxicity of pure nicotine with Nicotiana leaf extract at the same concentration of nicotine. An aqueous extract of dry leaves of Nicotiana gossei and a reference smokeless tobacco (CORESTA CRP2) were quantified for major pyridine alkaloids and TSNAs using HPLC-UV and LC-MS/MS. A range of extract concentrations and corresponding concentrations of nicotine standard were tested using an MTS assay to measure human lung epithelium cell (A549) survival. Cells treated for 24h with the maximum concentration of 1.5mg/ml of nicotine resulted in 77% viability. In contrast, extracts from N. gossei leaves and CRP2 containing a similar concentration of nicotine (1.3mg/ml) resulted in remarkably lower viability of 1.5 and 6%, respectively. Comparison of cytotoxicity of pure nicotine with that of the extracts revealed that nicotine was not the source of their cytotoxicity. Other biologically active compounds such as the known carcinogens NNK and NNN, derived from nicotine and nornicotine and found to be present in the smokeless tobacco extracts, may be responsible.

  3. Inhibition of in Vitro Pollen Tube Growth by Isolated S-Glycoproteins of Nicotiana alata.

    PubMed Central

    Jahnen, W.; Lush, W. M.; Clarke, A. E.

    1989-01-01

    Pollen from three S-genotypes of Nicotiana alata was grown in vitro in the presence of S-glycoproteins isolated from styles of the same three genotypes. Pollen germination was not affected by the presence of the S-glycoproteins, but pollen tube growth of all genotypes was inhibited. S2 pollen was preferentially inhibited by the S2-glycoprotein and S3 pollen by the S3-glycoprotein. The S6-glycoprotein preferentially inhibited growth of both S2 and S6 pollen over S3 pollen. Heat treatment dramatically increased the inhibitory activity of the S-glycoproteins as inhibitors both of pollen germination and tube growth; after heat treatment, S-allele specificity of pollen tube inhibition was not detected. PMID:12359898

  4. Wax esters of different compositions produced via engineering of leaf chloroplast metabolism in Nicotiana benthamiana.

    PubMed

    Aslan, Selcuk; Sun, Chuanxin; Leonova, Svetlana; Dutta, Paresh; Dörmann, Peter; Domergue, Frédéric; Stymne, Sten; Hofvander, Per

    2014-09-01

    In a future bio-based economy, renewable sources for lipid compounds at attractive cost are needed for applications where today petrochemical derivatives are dominating. Wax esters and fatty alcohols provide diverse industrial uses, such as in lubricant and surfactant production. In this study, chloroplast metabolism was engineered to divert intermediates from de novo fatty acid biosynthesis to wax ester synthesis. To accomplish this, chloroplast targeted fatty acyl reductases (FAR) and wax ester synthases (WS) were transiently expressed in Nicotiana benthamiana leaves. Wax esters of different qualities and quantities were produced providing insights to the properties and interaction of the individual enzymes used. In particular, a phytyl ester synthase was found to be a premium candidate for medium chain wax ester synthesis. Catalytic activities of FAR and WS were also expressed as a fusion protein and determined functionally equivalent to the expression of individual enzymes for wax ester synthesis in chloroplasts.

  5. Changes induced by the Pepper mild mottle tobamovirus on the chloroplast proteome of Nicotiana benthamiana.

    PubMed

    Pineda, M; Sajnani, C; Barón, M

    2010-01-01

    We have analyzed the chloroplast proteome of Nicotiana benthamiana using two-dimensional gel electrophoresis and mass spectrometry followed by a database search. In order to improve the resolution of the two-dimensional electrophoresis gels, we have made separate maps for the low and the high pH range. At least 200 spots were detected. We identified 72 polypeptides, some being isoforms of different multiprotein families. In addition, changes in this chloroplast proteome induced by the infection with the Spanish strain of the Pepper mild mottle virus were investigated. Viral infection induced the down-regulation of several chloroplastidic proteins involved in both the photosynthetic electron-transport chain and the Benson-Calvin cycle.

  6. Molecular Characterization of the Cercosporin Biosynthetic Pathway in the Fungal Plant Pathogen Cercospora nicotianae.

    PubMed

    Newman, Adam G; Townsend, Craig A

    2016-03-30

    Perylenequinones are a class of photoactivated polyketide mycotoxins produced by fungal plant pathogens that notably produce reactive oxygen species with visible light. The best-studied perylenequinone is cercosporin-a product of the Cercospora species. While the cercosporin biosynthetic gene cluster has been described in the tobacco pathogen Cercospora nicotianae, little is known of the metabolite's biosynthesis. Furthermore, in vitro investigations of the polyketide synthase central to cercosporin biosynthesis identified the naphthopyrone nor-toralactone as its direct product-an observation in conflict with published biosynthetic proposals. Here, we present an alternative biosynthetic pathway to cercosporin based on metabolites characterized from a series of biosynthetic gene knockouts. We show that nor-toralactone is the key polyketide intermediate and the substrate for the unusual didomain protein CTB3. We demonstrate the unique oxidative cleavage activity of the CTB3 monooxygenase domain in vitro. These data advance our understanding of perylenequinone biosynthesis and expand the biochemical repertoire of flavin-dependent monooxygenases.

  7. Production of Recombinant Cholera Toxin B Subunit in Nicotiana benthamiana Using GENEWARE® Tobacco Mosaic Virus Vector.

    PubMed

    Moore, Lauren; Hamorsky, Krystal; Matoba, Nobuyuki

    2016-01-01

    Here, we describe a method to produce a recombinant cholera toxin B subunit in Nicotiana benthamiana plants (CTBp) using the GENEWARE(®) tobacco mosaic virus vector system. Infectious transcripts of the vector RNA are generated in vitro and inoculated on N. benthamiana seedlings. After 11 days, CTBp is extracted in a simple tris buffer at room temperature. No protease inhibitor is required. The leaf homogenate is treated with mild heat and a pH shift to selectively precipitate host-derived proteins. CTBp is purified to >95 % homogeneity by two-step chromatography using immobilized metal affinity and ceramic hydroxyapatite resins. This procedure yields on average 400 mg of low-endotoxin CTBp from 1 kg of fresh leaf material.

  8. The transcriptome of Verticillium dahliae-infected Nicotiana benthamiana determined by deep RNA sequencing.

    PubMed

    Faino, Luigi; de Jonge, Ronnie; Thomma, Bart P H J

    2012-09-01

    Verticillium wilt disease is caused by fungi of the Verticillium genus that occur on a wide range of host plants, including Solanaceous species such as tomato and tobacco. Currently, the well characterized Ve1 gene of tomato is the only Verticillium wilt resistance gene cloned. During experiments to identify the Verticillium molecule that activates Ve1 resistance in tomato, RNA sequencing (RNA-Seq) of Verticillium-infected Nicotiana benthamiana was performed. In total, over 99% of the obtained reads were derived from N. benthamiana. Here, we report the assembly and annotation of the N. benthamiana transcriptome. In total, 142,738 transcripts > 100 bp were obtained, amounting to a total transcriptome size of 38.7 Mbp, which is comparable to the Arabidopsis transcriptome. About 30,282 transcripts could be annotated based on homology to Arabidopsis genes. By assembly of the N. benthamiana transcriptome, we provide a catalogue of transcripts of a Solanaceous model plant under pathogen stress.

  9. Polypeptide synthesis induced in Nicotiana clevelandii protoplasts by infection with raspberry ringspot nepovirus.

    PubMed

    Acosta, O; Mayo, M A

    1993-01-01

    Infection of Nicotiana clevelandii protoplasts by raspberry ringspot nepovirus resulted in the accumulation of about 24 polypeptides that differed in M(r) and pI from polypeptides accumulating in mock-inoculated protoplasts. Similar polypeptides accumulated in protoplasts infected with the S and E strains of RRV but different infection-specific polypeptides were detected in protoplasts infected with tobacco ringspot nepovirus. The M(r) of RRV-specific polypeptides ranged from 210,000 to 18,000 and most are presumed to be derived from others by proteolytic cleavage. No evidence was found for marked changes in polypeptide abundance with time after inoculation or for any virus-specific polypeptide becoming disproportionately abundant in the medium during culture.

  10. Modelling an infrared Man Portable Air Defence System

    NASA Astrophysics Data System (ADS)

    Birchenall, Richard P.; Richardson, Mark A.; Brian, Butters; Roy, Walmsley

    2010-09-01

    The global proliferation of shoulder launched IR Man Portable Air Defence Systems (ManPADS) has resulted in the existence of a serious threat to both civilian and military aircraft from terrorist attack. Some of the older generations of ManPADS can be defeated with modern countermeasures but even the most sophisticated protection still has vulnerabilities to the latest family of ManPADS. This paper describes the work undertaken by the authors to model a second generation ManPAD, based on the Russian SA-14, and assess the vulnerabilities of aircraft both with and without flare countermeasures from these systems. The conclusions are the results of over 11,000 simulated firings against targets of varying aspects, velocities and altitudes.

  11. Potato skin proteome is enriched with plant defence components

    PubMed Central

    Barel, Gilli; Ginzberg, Idit

    2008-01-01

    Periderm is a tissue of secondary origin that replaces damaged epidermis. It can be found in underground plant organs, as an above-ground tissue of woody species (cork), and as a wound-healing tissue. Its outer layers are composed of phellem cells with suberized walls that constitute a protective barrier, preventing pathogen invasion and fluid loss. In potato, a model for periderm studies, periderm tissue replaces the epidermis early in tuber development and the suberized phellems constitute the tuber's skin. To identify factors involved in phellem/skin development and that play a role in its defensive characteristics, two-dimensional gel electrophoresis was used to compare the skin and parenchymatic flesh proteomes of young developing tubers. Proteins exhibiting differentially high signal intensity in the skin were sorted by functional categories. As expected, the differential skin proteome was enriched in proteins whose activity is characteristic of actively dividing tissues such as cell proliferation, C1 metabolism, and the oxidative respiratory chain. Interestingly, the major functional category consisted of proteins (63%) involved in plant defence responses to biotic and abiotic stresses. This group included three isozymes of caffeoyl-CoA O-methyltransferase and five isozymes of peroxidase that may play a role in suberization processes. The differential expression of these proteins in the skin was further verified by RT-PCR of their corresponding transcripts in skin and tuber flesh samples. The results presented here shed light on the early events in skin development and further expand the concept of the periderm as a protective tissue containing an array of plant defence components. PMID:18653692

  12. Silicon-based plant defences, tooth wear and voles.

    PubMed

    Calandra, Ivan; Zub, Karol; Szafrańska, Paulina A; Zalewski, Andrzej; Merceron, Gildas

    2016-02-01

    Plant-herbivore interactions are hypothesized to drive vole population cycles through the grazing-induced production of phytoliths in leaves. Phytoliths act as mechanical defences because they deter herbivory and lower growth rates in mammals. However, how phytoliths impair herbivore performance is still unknown. Here, we tested whether the amount of phytoliths changes tooth wear patterns. If confirmed, abrasion from phytoliths could play a role in population crashes. We applied dental microwear texture analysis (DMTA) to laboratory and wild voles. Lab voles were fed two pelleted diets with differing amounts of silicon, which produced similar dental textures. This was most probably due to the loss of food mechanical properties through pelletization and/or the small difference in silicon concentration between diets. Wild voles were trapped in Poland during spring and summer, and every year across a population cycle. In spring, voles feed on silica-rich monocotyledons, while in the summer they also include silica-depleted dicotyledons. This was reflected in the results; the amount of silica therefore leaves a traceable record in the dental microwear texture of voles. Furthermore, voles from different phases of population cycles have different microwear textures. We tentatively propose that these differences result from grazing-induced phytolith concentrations. We hypothesize that the high amount of phytoliths in response to intense grazing in peak years may result in malocclusion and other dental abnormalities, which would explain how these silicon-based plant defences help provoke population crashes. DMTA could then be used to reconstruct vole population dynamics using teeth from pellets or palaeontological material.

  13. HYPXIM: an innovative hyperspectral satellite for science, security and defence

    NASA Astrophysics Data System (ADS)

    Lefevre-Fonollosa, Marie-José; Fratter, Isabelle; Mandea, Mioara

    2013-04-01

    We provide a broad overview of hyperspectral applications and data requirements gathered by an ad-hoc group of some twenty French scientists and defence users. This group known by as GSH (Groupe de Synthèse sur l'Hyperspectral) has addressed clear and detailed technical requirements for a high spatial resolution hyperspectral mission on the following themes: study of vegetation, coastal and inland water ecosystems, urban environment, atmospheric studies, and more widely, geosciences and security -defence matters. The synthesis of these requirements helped substantially to set up consolidated space-based system requirements (i.e. mission requirements) in terms of spectral domain, spectral resolution, signal-to-noise ratio, spatial resolution, swath and revisiting period, which revealed the main key drivers for the design of a very innovative hyperspectral space system. During the phase 0, CNES with the support of industry (Astrium et Thales Alenia Space) has compared two different scenario. The first one, named HYPXIM-C (HYPXIM-Challenging), aimed to finding out the highest possible resolution level (15m) achievable using a microsatellite platform, whereas the second scenario, called HYPXIM-P (HYPXIM-Performance), aimed to reach a higher spatial resolution (8m) and to provide a TIR hyperspectral capability. Recently, the HYPXIM phase A has been decided and it focuses on the most performing concept, however without TIR capabilities. The challenge for the selected HYPXIM mission is to design a high resolution spectroimager on an agile mini-satellite, at a reasonable cost. We will present the wide field HYPXIM core mission performance objectives, as well as the orbital parameters and mission scenarios.

  14. Brood parasitism selects for no defence in a cuckoo host.

    PubMed

    Krüger, Oliver

    2011-09-22

    In coevolutionary arms races, like between cuckoos and their hosts, it is easy to understand why the host is under selection favouring anti-parasitism behaviour, such as egg rejection, which can lead to parasites evolving remarkable adaptations to 'trick' their host, such as mimetic eggs. But what about cases where the cuckoo egg is not mimetic and where the host does not act against it? Classically, such apparently non-adaptive behaviour is put down to evolutionary lag: given enough time, egg mimicry and parasite avoidance strategies will evolve. An alternative is that absence of egg mimicry and of anti-parasite behaviour is stable. Such stability is at first sight highly paradoxical. I show, using both field and experimental data to parametrize a simulation model, that the absence of defence behaviour by Cape bulbuls (Pycnonotus capensis) against parasitic eggs of the Jacobin cuckoo (Clamator jacobinus) is optimal behaviour. The cuckoo has evolved massive eggs (double the size of bulbul eggs) with thick shells, making it very hard or impossible for the host to eject the cuckoo egg. The host could still avoid brood parasitism by nest desertion. However, higher predation and parasitism risks later in the season makes desertion more costly than accepting the cuckoo egg, a strategy aided by the fact that many cuckoo eggs are incorrectly timed, so do not hatch in time and hence do not reduce host fitness to zero. Selection will therefore prevent the continuation of any coevolutionary arms race. Non-mimetic eggs and absence of defence strategies against cuckoo eggs will be the stable, if at first sight paradoxical, result.

  15. Potato skin proteome is enriched with plant defence components.

    PubMed

    Barel, Gilli; Ginzberg, Idit

    2008-01-01

    Periderm is a tissue of secondary origin that replaces damaged epidermis. It can be found in underground plant organs, as an above-ground tissue of woody species (cork), and as a wound-healing tissue. Its outer layers are composed of phellem cells with suberized walls that constitute a protective barrier, preventing pathogen invasion and fluid loss. In potato, a model for periderm studies, periderm tissue replaces the epidermis early in tuber development and the suberized phellems constitute the tuber's skin. To identify factors involved in phellem/skin development and that play a role in its defensive characteristics, two-dimensional gel electrophoresis was used to compare the skin and parenchymatic flesh proteomes of young developing tubers. Proteins exhibiting differentially high signal intensity in the skin were sorted by functional categories. As expected, the differential skin proteome was enriched in proteins whose activity is characteristic of actively dividing tissues such as cell proliferation, C(1) metabolism, and the oxidative respiratory chain. Interestingly, the major functional category consisted of proteins (63%) involved in plant defence responses to biotic and abiotic stresses. This group included three isozymes of caffeoyl-CoA O-methyltransferase and five isozymes of peroxidase that may play a role in suberization processes. The differential expression of these proteins in the skin was further verified by RT-PCR of their corresponding transcripts in skin and tuber flesh samples. The results presented here shed light on the early events in skin development and further expand the concept of the periderm as a protective tissue containing an array of plant defence components.

  16. The Only African Wild Tobacco, Nicotiana africana: Alkaloid Content and the Effect of Herbivory

    PubMed Central

    Marlin, Danica; Nicolson, Susan W.; Yusuf, Abdullahi A.; Stevenson, Philip C.; Heyman, Heino M.; Krüger, Kerstin

    2014-01-01

    Herbivory in some Nicotiana species is known to induce alkaloid production. This study examined herbivore-induced defenses in the nornicotine-rich African tobacco N. africana, the only Nicotiana species indigenous to Africa. We tested the predictions that: 1) N. africana will have high constitutive levels of leaf, flower and nectar alkaloids; 2) leaf herbivory by the African bollworm Helicoverpa armigera will induce increased alkaloid levels in leaves, flowers and nectar; and 3) increased alkaloid concentrations in herbivore-damaged plants will negatively affect larval growth. We grew N. africana in large pots in a greenhouse and exposed flowering plants to densities of one, three and six fourth-instar larvae of H. armigera, for four days. Leaves, flowers and nectar were analyzed for nicotine, nornicotine and anabasine. The principal leaf alkaloid was nornicotine (mean: 28 µg/g dry mass) followed by anabasine (4.9 µg/g) and nicotine (0.6 µg/g). Nornicotine was found in low quantities in the flowers, but no nicotine or anabasine were recorded. The nectar contained none of the alkaloids measured. Larval growth was reduced when leaves of flowering plants were exposed to six larvae. As predicted by the optimal defense theory, herbivory had a localized effect and caused an increase in nornicotine concentrations in both undamaged top leaves of herbivore damaged plants and herbivore damaged leaves exposed to one and three larvae. The nicotine concentration increased in damaged compared to undamaged middle leaves. The nornicotine concentration was lower in damaged leaves of plants exposed to six compared to three larvae, suggesting that N. africana rather invests in new growth as opposed to protecting older leaves under severe attack. The results indicate that the nornicotine-rich N. africana will be unattractive to herbivores and more so when damaged, but that potential pollinators will be unaffected because the nectar remains alkaloid-free even after herbivory. PMID

  17. Membrane transporters in self resistance of Cercospora nicotianae to the photoactivated toxin cercosporin.

    PubMed

    Beseli, Aydin; Amnuaykanjanasin, Alongkorn; Herrero, Sonia; Thomas, Elizabeth; Daub, Margaret E

    2015-11-01

    The goal of this work is to characterize membrane transporter genes in Cercospora fungi required for autoresistance to the photoactivated, active-oxygen-generating toxin cercosporin they produce for infection of host plants. Previous studies implicated a role for diverse membrane transporters in cercosporin resistance. In this study, transporters identified in a subtractive cDNA library between a Cercospora nicotianae wild type and a cercosporin-sensitive mutant were characterized, including two ABC transporters (CnATR2, CnATR3), an MFS transporter (CnMFS2), a uracil transporter, and a zinc transport protein. Phylogenetic analysis showed that only CnATR3 clustered with transporters previously characterized to be involved in cercosporin resistance. Quantitative RT-PCR analysis of gene expression under conditions of cercosporin toxicity, however, showed that only CnATR2 was upregulated, thus this gene was selected for further characterization. Transformation and expression of CnATR2 in the cercosporin-sensitive fungus Neurospora crassa significantly increased cercosporin resistance. Targeted gene disruption of CnATR2 in the wild type C. nicotianae, however, did not decrease resistance. Expression analysis of other transporters in the cnatr2 mutant under conditions of cercosporin toxicity showed significant upregulation of the cercosporin facilitator protein gene (CFP), encoding an MFS transporter previously characterized as playing an important role in cercosporin autoresistance in Cercospora species. We conclude that cercosporin autoresistance in Cercospora is mediated by multiple genes, and that the fungus compensates for mutations by up-regulation of other resistance genes. CnATR2 may be a useful gene, alone or in addition to other known resistance genes, for engineering Cercospora resistance in crop plants.

  18. Cercosporin-deficient mutants by plasmid tagging in the asexual fungus Cercospora nicotianae.

    PubMed

    Chung, K-R; Ehrenshaft, M; Wetzel, D K; Daub, M E

    2003-11-01

    We have successfully adapted plasmid insertion and restriction enzyme-mediated integration (REMI) to produce cercosporin toxin-deficient mutants in the asexual phytopathogenic fungus Cercospora nicotianae. The use of pre-linearized plasmid or restriction enzymes in the transformation procedure significantly decreased the transformation frequency, but promoted a complicated and undefined mode of plasmid integration that leads to mutations in the C. nicotianae genome. Vector DNA generally integrated in multiple copies, and no increase in single-copy insertion was observed when enzymes were added to the transformation mixture. Out of 1873 transformants tested, 39 putative cercosporin toxin biosynthesis ( ctb) mutants were recovered that showed altered levels of cercosporin production. Seven ctb mutants were recovered using pre-linearized plasmids without the addition of enzymes, and these were considered to be non-REMI mutants. The correlation between a specific insertion and a mutant phenotype was confirmed using rescued plasmids as gene disruption vectors in the wild-type strain. Six out of fifteen rescued plasmids tested yielded cercosporin-deficient transformants when re-introduced into the wild-type strain, suggesting a link between the insertion site and the cercosporin-deficient phenotype. Sequence analysis of a fragment flanking the insert site recovered from one insertion mutant showed it to be disrupted in sequences with high homology to the acyl transferase domain of polyketide synthases from other fungi. Disruption of this polyketide synthase gene ( CTB1) using a rescued plasmid resulted in mutants that were defective in cercosporin production. Thus, we provide the first molecular evidence that cercosporin is synthesized via a polyketide pathway as previously hypothesized.

  19. Expression, Purification, and Biophysical Characterization of a Secreted Anthrax Decoy Fusion Protein in Nicotiana benthamiana

    PubMed Central

    Karuppanan, Kalimuthu; Duhra-Gill, Sifti; Kailemia, Muchena J.; Phu, My L.; Lebrilla, Carlito B.; Dandekar, Abhaya M.; Rodriguez, Raymond L.; Nandi, Somen; McDonald, Karen A.

    2017-01-01

    Anthrax toxin receptor-mediated drug development for blocking anthrax toxin action has received much attention in recent decades. In this study, we produced a secreted anthrax decoy fusion protein comprised of a portion of the human capillary morphogenesis gene-2 (CMG2) protein fused via a linker to the fragment crystallizable (Fc) domain of human immunoglobulin G1 in Nicotiana benthamiana plants using a transient expression system. Using the Cauliflower Mosaic Virus (CaMV) 35S promoter and co-expression with the p19 gene silencing suppressor, we were able to achieve a high level of recombinant CMG2-Fc-Apo (rCMG2-Fc-Apo) protein accumulation. Production kinetics were observed up to eight days post-infiltration, and maximum production of 826 mg/kg fresh leaf weight was observed on day six. Protein A affinity chromatography purification of the rCMG2-Fc-Apo protein from whole leaf extract and apoplast wash fluid showed the homodimeric form under non-reducing gel electrophoresis and mass spectrometry analysis confirmed the molecular integrity of the secreted protein. The N-glycosylation pattern of purified rCMG2-Fc-Apo protein was analysed; the major portion of N-glycans consists of complex type structures in both protein samples. The most abundant (>50%) N-glycan structure was GlcNAc2(Xyl)Man3(Fuc)GlcNAc2 in rCMG2-Fc-Apo recovered from whole leaf extract and apoplast wash fluid. High mannose N-glycan structures were not detected in the apoplast wash fluid preparation, which confirmed the protein secretion. Altogether, these findings demonstrate that high-level production of rCMG2-Fc-Apo can be achieved by transient production in Nicotiana benthamiana plants with apoplast targeting. PMID:28054967

  20. Metabolomic analysis of wild and transgenic Nicotiana langsdorffii plants exposed to abiotic stresses: unraveling metabolic responses.

    PubMed

    Scalabrin, Elisa; Radaelli, Marta; Rizzato, Giovanni; Bogani, Patrizia; Buiatti, Marcello; Gambaro, Andrea; Capodaglio, Gabriele

    2015-08-01

    Nicotiana langsdorffii plants, wild and transgenic for the Agrobacterium rhizogenes rol C gene and the rat glucocorticoid receptor (GR) gene, were exposed to different abiotic stresses (high temperature, water deficit, and high chromium concentrations). An untargeted metabolomic analysis was carried out in order to investigate the metabolic effects of the inserted genes in response to the applied stresses and to obtain a comprehensive profiling of metabolites induced during abiotic stresses. High-performance liquid chromatography separation (HPLC) coupled to high-resolution mass spectrometry (HRMS) enabled the identification of more than 200 metabolites, and statistical analysis highlighted the most relevant compounds for each plant treatment. The plants exposed to heat stress showed a unique set of induced secondary metabolites, some of which were known while others were not previously reported for this kind of stress; significant changes were observed especially in lipid composition. The role of trichome, as a protection against heat stress, is here suggested by the induction of both acylsugars and glykoalkaloids. Water deficit and Cr(VI) stresses resulted mainly in enhanced antioxidant (HCAs, polyamine) levels and in the damage of lipids, probably as a consequence of reactive oxygen species (ROS) production. Moreover, the ability of rol C expression to prevent oxidative burst was confirmed. The results highlighted a clear influence of GR modification on plant stress response, especially to water deficiency-a phenomenon whose applications should be further investigated. This study provides new insights into the field of system biology and demonstrates the importance of metabolomics in the study of plant functioning. Graphical Abstract Untargeted metabolomic analysis was applied to wild type, GR and RolC modified Nicotiana Langsdorffii plants exposed to heat, water and Cr(VI) stresses. The key metabolites, highly affected by stress application, were identified

  1. Necrotic Lesion Resistance Induced by Peronospora tabacina on Leaves of Nicotiana obtusifolia.

    PubMed

    Heist, E P; Zaitlin, D; Funnell, D L; Nesmith, W C; Schardl, C L

    2004-11-01

    ABSTRACT Infection of Nicotiana obtusifolia plant introduction (PI) #555573 by the downy mildew pathogen Peronospora tabacina resulted in a compatible interaction, in which P. tabacina penetrated and freely colonized host leaf tissue. This interaction became incompatible 5 to 6 days later, with the appearance of necrotic lesions (NLs) and inhibition of pathogen growth and subsequent sporulation. NL development depended upon the presence of P. tabacina in host tissue, was not due to the effects of other microbes, and occurred co-incident in time with the pathogen's ability to produce asexual sporangia on a susceptible N. obtusifolia genotype. Inhibition of the necrotic response by CoCl(2) (a calcium channel blocker) and pathogen-induced transcription of a defense-related gene (PR-1a) suggested that necrosis was due to hypersensitive cell death in the host. In contrast, N. obtusifolia PI#555543 did not exhibit hypersensitivity upon infection by P. tabacina, but rather developed characteristic symptoms of tobacco blue mold disease: chlorotic lesions accompanied by abundant pathogen sporulation. Disease reactions scored on PI#555573 x PI#555543 F(2) progeny inoculated with P. tabacina sporangia indicated that the resistance phenotype was due to the action of a single gene from N. obtusifolia PI#555573, which we have named Rpt1. To date, Rpt1 is the only gene known to confer a hypersensitive response (HR) to P. tabacina infection in any species of Nicotiana. A survey of wild N. obtusifolia revealed that the HR to P. tabacina was expressed in the progeny of 7 of 21 (33%) plants collected in southern Arizona, but not in the progeny of plants originating from Death Valley National Park in California and the Big Bend National Park in west Texas.

  2. Mechanisms and ecological consequences of plant defence induction and suppression in herbivore communities

    PubMed Central

    Kant, M. R.; Jonckheere, W.; Knegt, B.; Lemos, F.; Liu, J.; Schimmel, B. C. J.; Villarroel, C. A.; Ataide, L. M. S.; Dermauw, W.; Glas, J. J.; Egas, M.; Janssen, A.; Van Leeuwen, T.; Schuurink, R. C.; Sabelis, M. W.; Alba, J. M.

    2015-01-01

    Background Plants are hotbeds for parasites such as arthropod herbivores, which acquire nutrients and energy from their hosts in order to grow and reproduce. Hence plants are selected to evolve resistance, which in turn selects for herbivores that can cope with this resistance. To preserve their fitness when attacked by herbivores, plants can employ complex strategies that include reallocation of resources and the production of defensive metabolites and structures. Plant defences can be either prefabricated or be produced only upon attack. Those that are ready-made are referred to as constitutive defences. Some constitutive defences are operational at any time while others require activation. Defences produced only when herbivores are present are referred to as induced defences. These can be established via de novo biosynthesis of defensive substances or via modifications of prefabricated substances and consequently these are active only when needed. Inducibility of defence may serve to save energy and to prevent self-intoxication but also implies that there is a delay in these defences becoming operational. Induced defences can be characterized by alterations in plant morphology and molecular chemistry and are associated with a decrease in herbivore performance. These alterations are set in motion by signals generated by herbivores. Finally, a subset of induced metabolites are released into the air as volatiles and function as a beacon for foraging natural enemies searching for prey, and this is referred to as induced indirect defence. Scope The objective of this review is to evaluate (1) which strategies plants have evolved to cope with herbivores and (2) which traits herbivores have evolved that enable them to counter these defences. The primary focus is on the induction and suppression of plant defences and the review outlines how the palette of traits that determine induction/suppression of, and resistance/susceptibility of herbivores to, plant defences can

  3. Independent Effects of a Herbivore's Bacterial Symbionts on Its Performance and Induced Plant Defences.

    PubMed

    Staudacher, Heike; Schimmel, Bernardus C J; Lamers, Mart M; Wybouw, Nicky; Groot, Astrid T; Kant, Merijn R

    2017-01-18

    It is well known that microbial pathogens and herbivores elicit defence responses in plants. Moreover, microorganisms associated with herbivores, such as bacteria or viruses, can modulate the plant's response to herbivores. Herbivorous spider mites can harbour different species of bacterial symbionts and exert a broad range of effects on host-plant defences. Hence, we tested the extent to which such symbionts affect the plant's defences induced by their mite host and assessed if this translates into changes in plant resistance. We assessed the bacterial communities of two strains of the common mite pest Tetranychus urticae. We found that these strains harboured distinct symbiotic bacteria and removed these using antibiotics. Subsequently, we tested to which extent mites with and without symbiotic bacteria induce plant defences in terms of phytohormone accumulation and defence gene expression, and assessed mite oviposition and survival as a measure for plant resistance. We observed that the absence/presence of these bacteria altered distinct plant defence parameters and affected mite performance but we did not find indications for a causal link between the two. We argue that although bacteria-related effects on host-induced plant defences may occur, these do not necessarily affect plant resistance concomitantly.

  4. Genetic dissection of basal defence responsiveness in accessions of Arabidopsis thaliana.

    PubMed

    Ahmad, Shakoor; Van Hulten, Marieke; Martin, Janet; Pieterse, Corné M J; Van Wees, Saskia C M; Ton, Jurriaan

    2011-07-01

    Basal resistance involves a multitude of pathogen- and herbivore-inducible defence mechanisms, ranging from localized callose deposition to systemic defence gene induction by salicylic acid (SA) and jasmonic acid (JA). In this study, we have explored and dissected genetic variation in the responsiveness of basal defence mechanisms within a selection of Arabidopsis accessions. Responsiveness of JA-induced PDF1.2 gene expression was associated with enhanced basal resistance against the necrotrophic fungus Plectosphaerella cucumerina and the herbivore Spodoptera littoralis. Conversely, accessions showing augmented PR-1 induction upon SA treatment were more resistant to the hemi-biotrophic pathogen Pseudomonas syringae, and constitutively expressed defence-related transcription factor (TF) genes. Unexpectedly, accessions with primed responsiveness to SA deposited comparatively little callose after treatment with microbe-associated molecular patterns. A quantitative trait locus (QTL) analysis identified two loci regulating flagellin-induced callose and one locus regulating SA-induced PR-1 expression. The latter QTL was found to contribute to basal resistance against P. syringae. None of the defence regulatory QTLs influenced plant growth, suggesting that the constitutive defence priming conferred by these loci is not associated with major costs on plant growth. Our study demonstrates that natural variation in basal resistance can be exploited to identify genetic loci that prime the plant's basal defence arsenal.

  5. Independent Effects of a Herbivore’s Bacterial Symbionts on Its Performance and Induced Plant Defences

    PubMed Central

    Staudacher, Heike; Schimmel, Bernardus C. J.; Lamers, Mart M.; Wybouw, Nicky; Groot, Astrid T.; Kant, Merijn R.

    2017-01-01

    It is well known that microbial pathogens and herbivores elicit defence responses in plants. Moreover, microorganisms associated with herbivores, such as bacteria or viruses, can modulate the plant’s response to herbivores. Herbivorous spider mites can harbour different species of bacterial symbionts and exert a broad range of effects on host-plant defences. Hence, we tested the extent to which such symbionts affect the plant’s defences induced by their mite host and assessed if this translates into changes in plant resistance. We assessed the bacterial communities of two strains of the common mite pest Tetranychus urticae. We found that these strains harboured distinct symbiotic bacteria and removed these using antibiotics. Subsequently, we tested to which extent mites with and without symbiotic bacteria induce plant defences in terms of phytohormone accumulation and defence gene expression, and assessed mite oviposition and survival as a measure for plant resistance. We observed that the absence/presence of these bacteria altered distinct plant defence parameters and affected mite performance but we did not find indications for a causal link between the two. We argue that although bacteria-related effects on host-induced plant defences may occur, these do not necessarily affect plant resistance concomitantly. PMID:28106771

  6. Collective defence portfolios of ant hosts shift with social parasite pressure.

    PubMed

    Jongepier, Evelien; Kleeberg, Isabelle; Job, Sylwester; Foitzik, Susanne

    2014-09-22

    Host defences become increasingly costly as parasites breach successive lines of defence. Because selection favours hosts that successfully resist parasitism at the lowest possible cost, escalating coevolutionary arms races are likely to drive host defence portfolios towards ever more expensive strategies. We investigated the interplay between host defence portfolios and social parasite pressure by comparing 17 populations of two Temnothorax ant species. When successful, collective aggression not only prevents parasitation but also spares host colonies the cost of searching for and moving to a new nest site. However, once parasites breach the host's nest defence, host colonies should resort to flight as the more beneficial resistance strategy. We show that under low parasite pressure, host colonies more likely responded to an intruding Protomognathus americanus slavemaker with collective aggression, which prevented the slavemaker from escaping and potentially recruiting nest-mates. However, as parasite pressure increased, ant colonies of both host species became more likely to flee rather than to fight. We conclude that host defence portfolios shift consistently with social parasite pressure, which is in accordance with the degeneration of frontline defences and the evolution of subsequent anti-parasite strategies often invoked in hosts of brood parasites.

  7. Metabolomic Assessment of Induced and Activated Chemical Defence in the Invasive Red Alga Gracilaria vermiculophylla

    PubMed Central

    Nylund, Göran M.; Weinberger, Florian; Rempt, Martin; Pohnert, Georg

    2011-01-01

    In comparison with terrestrial plants the mechanistic knowledge of chemical defences is poor for marine macroalgae. This restricts our understanding in the chemically mediated interactions that take place between algae and other organisms. Technical advances such as metabolomics, however, enable new approaches towards the characterisation of the chemically mediated interactions of organisms with their environment. We address defence responses in the red alga Gracilaria vermiculophylla using mass spectrometry based metabolomics in combination with bioassays. Being invasive in the north Atlantic this alga is likely to possess chemical defences according to the prediction that well-defended exotics are most likely to become successful invaders in systems dominated by generalist grazers, such as marine macroalgal communities. We investigated the effect of intense herbivore feeding and simulated herbivory by mechanical wounding of the algae. Both processes led to similar changes in the metabolic profile. Feeding experiments with the generalist isopod grazer Idotea baltica showed that mechanical wounding caused a significant increase in grazer resistance. Structure elucidation of the metabolites of which some were up-regulated more than 100 times in the wounded tissue, revealed known and novel eicosanoids as major components. Among these were prostaglandins, hydroxylated fatty acids and arachidonic acid derived conjugated lactones. Bioassays with pure metabolites showed that these eicosanoids are part of the innate defence system of macroalgae, similarly to animal systems. In accordance with an induced defence mechanism application of extracts from wounded tissue caused a significant increase in grazer resistance and the up-regulation of other pathways than in the activated defence. Thus, this study suggests that G. vermiculophylla chemically deters herbivory by two lines of defence, a rapid wound-activated process followed by a slower inducible defence. By unravelling

  8. Metabolomic assessment of induced and activated chemical defence in the invasive red alga Gracilaria vermiculophylla.

    PubMed

    Nylund, Göran M; Weinberger, Florian; Rempt, Martin; Pohnert, Georg

    2011-01-01

    In comparison with terrestrial plants the mechanistic knowledge of chemical defences is poor for marine macroalgae. This restricts our understanding in the chemically mediated interactions that take place between algae and other organisms. Technical advances such as metabolomics, however, enable new approaches towards the characterisation of the chemically mediated interactions of organisms with their environment. We address defence responses in the red alga Gracilaria vermiculophylla using mass spectrometry based metabolomics in combination with bioassays. Being invasive in the north Atlantic this alga is likely to possess chemical defences according to the prediction that well-defended exotics are most likely to become successful invaders in systems dominated by generalist grazers, such as marine macroalgal communities. We investigated the effect of intense herbivore feeding and simulated herbivory by mechanical wounding of the algae. Both processes led to similar changes in the metabolic profile. Feeding experiments with the generalist isopod grazer Idotea baltica showed that mechanical wounding caused a significant increase in grazer resistance. Structure elucidation of the metabolites of which some were up-regulated more than 100 times in the wounded tissue, revealed known and novel eicosanoids as major components. Among these were prostaglandins, hydroxylated fatty acids and arachidonic acid derived conjugated lactones. Bioassays with pure metabolites showed that these eicosanoids are part of the innate defence system of macroalgae, similarly to animal systems. In accordance with an induced defence mechanism application of extracts from wounded tissue caused a significant increase in grazer resistance and the up-regulation of other pathways than in the activated defence. Thus, this study suggests that G. vermiculophylla chemically deters herbivory by two lines of defence, a rapid wound-activated process followed by a slower inducible defence. By unravelling

  9. The cytoskeleton in cell-autonomous immunity: structural determinants of host defence

    PubMed Central

    Mostowy, Serge; Shenoy, Avinash R.

    2016-01-01

    Host cells use antimicrobial proteins, pathogen-restrictive compartmentalization and cell death in their defence against intracellular pathogens. Recent work has revealed that four components of the cytoskeleton — actin, microtubules, intermediate filaments and septins, which are well known for their roles in cell division, shape and movement — have important functions in innate immunity and cellular self-defence. Investigations using cellular and animal models have shown that these cytoskeletal proteins are crucial for sensing bacteria and for mobilizing effector mechanisms to eliminate them. In this Review, we highlight the emerging roles of the cytoskeleton as a structural determinant of cell-autonomous host defence. PMID:26292640

  10. The cytoskeleton in cell-autonomous immunity: structural determinants of host defence.

    PubMed

    Mostowy, Serge; Shenoy, Avinash R

    2015-09-15

    Host cells use antimicrobial proteins, pathogen-restrictive compartmentalization and cell death in their defence against intracellular pathogens. Recent work has revealed that four components of the cytoskeleton--actin, microtubules, intermediate filaments and septins, which are well known for their roles in cell division, shape and movement--have important functions in innate immunity and cellular self-defence. Investigations using cellular and animal models have shown that these cytoskeletal proteins are crucial for sensing bacteria and for mobilizing effector mechanisms to eliminate them. In this Review, we highlight the emerging roles of the cytoskeleton as a structural determinant of cell-autonomous host defence.

  11. Cladosporium fulvum CfHNNI1 induces hypersensitive necrosis, defence gene expression and disease resistance in both host and nonhost plants.

    PubMed

    Cai, Xin-Zhong; Zhou, Xin; Xu, You-Ping; Joosten, Matthieu H A J; de Wit, Pierre J G M

    2007-05-01

    Nonhost resistance as a durable and broad-spectrum defence strategy is of great potential for agricultural applications. We have previously isolated a cDNA showing homology with genes encoding bZIP transcription factors from tomato leaf mould pathogen Cladosporium fulvum. Upon expression, the cDNA results in necrosis in C. fulvum host tomato and nonhost tobacco plants and is thus named CfHNNI1 (for C . f ulvum host and nonhost plant necrosis inducer 1). In the present study we report the induction of necrosis in a variety of nonhost plant species belonging to three families by the transient in planta expression of CfHNNI1 using virus-based vectors. Additionally, transient expression of CfHNNI1 also induced expression of the HR marker gene LeHSR203 and greatly reduced the accumulation of recombinant Potato virus X. Stable CfHNNI1 transgenic tobacco plants were generated in which the expression of CfHNNI1 is under the control of the pathogen-inducible hsr203J promoter. When infected with the oomycetes pathogen Phytophthora parasitica var. nicotianae, these transgenic plants manifested enhanced expression of CfHNNI1 and subsequent accumulation of CfHNNI1 protein, resulting in high expression of the HSR203J and PR genes, and strong resistance to the pathogen. The CfHNNI1 transgenic plants also exhibited induced resistance to Pseudomonas syringae pv. tabaci and Tobacco mosaic virus. Furthermore, CfHNNI1 was highly expressed and the protein was translocated into plant cells during the incompatible interactions between C. fulvum and host and nonhost plants. Our results demonstrate that CfHNNI1 is a potential general elicitor of hypersensitive response and nonhost resistance.

  12. BjMYB1, a transcription factor implicated in plant defence through activating BjCHI1 chitinase expression by binding to a W-box-like element

    PubMed Central

    Gao, Ying; Jia, Shuangwei; Wang, Chunlian; Wang, Fujun; Wang, Fajun; Zhao, Kaijun

    2016-01-01

    We previously identified the W-box-like-4 (Wbl-4) element (GTAGTGACTCAT), one of six Wbl elements in the BjC-P promoter of the unusual chitinase gene BjCHI1 from Brassica juncea, as the core element responsive to fungal infection. Here, we report the isolation and characterization of the cognate transcription factor interacting with the Wbl-4 element. Using Wbl-4 as a target, we performed yeast one-hybrid screening of a B. juncea cDNA library and isolated an R2R3-MYB transcription factor designated as BjMYB1. BjMYB1 was localized in the nucleus of plant cells. EMSA assays confirmed that BjMYB1 binds to the Wbl-4 element. Transiently expressed BjMYB1 up-regulated the activity of the BjC-P promoter through its binding to the Wbl-4 element in tobacco (Nicotiana benthamiana) leaves. In B. juncea, BjMYB1 displayed a similar induced expression pattern as that of BjCHI1 upon infection by the fungus Botrytis cinerea. Moreover, heterogeneous overexpression of BjMYB1 significantly elevated the resistance of transgenic Arabidopsis thaliana to the fungus B. cinerea. These results suggest that BjMYB1 is potentially involved in host defence against fungal attack through activating the expression of BjCHI1 by binding to the Wbl-4 element in the BjC-P promoter. This finding demonstrates a novel DNA target of plant MYB transcription factors. PMID:27353280

  13. Simultaneous detection and quantification of Phytophthora nicotianae and P. cactorum, and distribution analyses in strawberry greenhouses by duplex real-time PCR.

    PubMed

    Li, Mingzhu; Inada, Minoru; Watanabe, Hideki; Suga, Haruhisa; Kageyama, Koji

    2013-01-01

    Phytophthora nicotianae and P. cactorum cause Phytophthora rot of strawberry. A duplex real-time PCR technique for simultaneous detection and quantification of the two pathogens was developed. Species-specific primers for P. nicotianae and P. cactorum were designed based on the internal transcribed spacer regions (ITS) of rDNA and the ras-related protein gene Ypt1, respectively. TaqMan probes were labeled with FAM for P. nicotianae and HEX for P. cactorum. Specificities were demonstrated using 52 isolates, including various soil-borne pathogens. Sensitivities for P. nicotianae and P. cactorum DNAs were 10 fg and 1 pg, respectively. The technique was applied to naturally infested soil and root samples; the two pathogens were detected and the target DNA concentrations were quantified. Significant correlations of DNA quantities in roots and the surrounding soils were found. The minimum soil DNA concentration predicting the development of disease symptoms was estimated as 20 pg (g soil)(-1). In three strawberry greenhouses examined, the target DNA concentrations ranged from 1 to 1,655 pg (g soil)(-1) for P. nicotianae and from 13 to 233 pg (g soil)(-1) for P. cactorum. The method proved fast and reliable, and provides a useful tool to monitor P. nicotianae and P. cactorum in plants or soils.

  14. Functional characterization of SOR1, a gene required for resistance to photosensitizing toxins in the fungus Cercospora nicotianae.

    PubMed

    Ehrenshaft, M; Chung, K R; Jenns, A E; Daub, M E

    1999-01-01

    The Cercospora nicotianae SOR1 gene is required for resistance to singlet oxygen-generating photosensitizers. SOR1 was characterized in the wild-type and in five photosensitizer-sensitive mutant strains which are complemented to photosensitizer resistance by transformation with SOR1. Sequence analysis determined that three of the mutants contain SOR1 copies with mutations encoding substitutions in the protein-coding sequence; however, two other mutants had wild-type SOR1 protein and promoter sequences. All five mutants accumulate SOR1 mRNA at levels comparable to that of the wild-type strain. In the wild-type strain, SOR1 accumulation is enhanced two-fold by light, but is unaffected by the presence of cercosporin, the photosensitizer synthesized by C. nicotianae. Southern analysis indicates that SOR1 is present in other fungi that synthesize structurally related perylenequinone photosensitizers.

  15. Formation of Defence Primary Healthcare: a new way of delivering firm base primary healthcare.

    PubMed

    Burgess, John E; Gall, M; Orr, S; Kilbey, S

    2016-06-09

    Following the Strategic Defence and Security Review of 2010, the UK Surgeon General was directed to merge the delivery of primary healthcare from the three single Service organisations to a unified Defence Primary Healthcare. Although front line clinical staff were to be preserved, considerable savings were to be made in headquarters staff. This was one of the largest UK military medicine changes in delivery for a generation. The changes were completed on time with the transfer of UK and overseas general practice, specialist community services and dentistry, with a later requirement to add healthcare for the Reserves. The first years of this initiative have been remarkably successful, and Defence Primary Healthcare (DPHC) has progressively increased performance in all the QOF criteria measured by Defence Statistics.

  16. Probiotics to enhance anti-infective defences in the gastrointestinal tract.

    PubMed

    Gill, Harsharnjit S

    2003-10-01

    Several clinical studies have demonstrated the therapeutic and/or prophylactic efficacy of specific probiotics against acute viral gastroenteritis and antibiotic-associated diarrhoea (including Clostridium difficile infection). Emerging evidence also suggests beneficial effects against Helicobacter pylori infection. The evidence of efficacy against traveller's diarrhoea remains, however, inconclusive. The precise mechanisms by which probiotics potentiate host gastrointestinal defences and mediate protection are not fully known. There is evidence to suggest, however, that probiotics might contribute to host defence by reinforcing non-immunological defences and stimulating both specific and non-specific host immune responses. Little is known about the relative importance of the probiotic-stimulated mechanisms in host protection. This review summarises the evidence for the anti-infective effects of probiotics and discusses the effect of orally delivered probiotics on non-immunological and immunological defence mechanisms in the host, especially in the gastrointestinal tract.

  17. House finches (Carpodacus mexicanus) balance investment in behavioural and immunological defences against pathogens.

    PubMed

    Zylberberg, Maxine; Klasing, Kirk C; Hahn, Thomas P

    2013-02-23

    Infection with parasites and pathogens is costly for hosts, causing loss of nutritional resources, reproductive potential, tissue integrity and even life. In response, animals have evolved behavioural and immunological strategies to avoid infection by pathogens and infestation by parasites. Scientists generally study these strategies in isolation from each other; however, since these defences entail costs, host individuals should benefit from balancing investment in these strategies, and understanding of infectious disease dynamics would benefit from studying the relationship between them. Here, we show that Carpodacus mexicanus (house finches) avoid sick individuals. Moreover, we show that individuals investing less in behavioural defences invest more in immune defences. Such variation has important implications for the dynamics of pathogen spread through populations, and ultimately the course of epidemics. A deeper understanding of individual- and population-level disease defence strategies will improve our ability to understand, model and predict the outcomes of pathogen spread in wildlife.

  18. Trade-off among different anti-herbivore defence strategies along an altitudinal gradient

    PubMed Central

    Dostálek, Tomáš; Rokaya, Maan Bahadur; Maršík, Petr; Rezek, Jan; Skuhrovec, Jiří; Pavela, Roman; Münzbergová, Zuzana

    2016-01-01

    The type and intensity of plant–herbivore interactions are likely to be altered under climate change as a consequence of differential dispersal rates of plants and their herbivores. Here, we studied variation in herbivore damage on Salvia nubicola in the field and compared its growth and defence strategies against herbivores in controlled conditions using seeds from populations along a broad altitudinal gradient. Our work is one of the first studies to simultaneously measure complex intraspecific variation in plant growth, direct and indirect defences as well as plant tolerance (ability to regrow) as a consequence of herbivore attack simulated by clipping. In the field, we found that plants experienced higher herbivore pressure in lower altitudes. In the greenhouse, plants grown from seeds collected in lower-altitude populations grew better and produced a higher content of phenolic compounds (direct defence) and volatile organic compounds (indirect defence) in response to simulated herbivory. However, there were no differences in tolerance and effect of S. nubicola extracts on the model generalist herbivore Spodoptera littoralis (direct defence) along the altitudinal gradient. Although we found that S. nubicola developed a range of defence strategies, the strategies do not seem to be used simultaneously in all populations even though most of them are correlated with altitudinal gradient. Our finding is in agreement with the current knowledge that co-expression of multiple defences might be costly for a plant, since investment in defensive traits is assumed to reduce the resource availability for growth and reproduction. Our study thus shows the importance of simultaneous study of different defence strategies since understanding these trade-offs could be necessary for detecting the mechanisms by which plants are able to cope with future climate change. PMID:27169609

  19. Conformal Load-Bearing Antenna Structure for Australian Defence Force Aircraft

    DTIC Science & Technology

    2007-03-01

    while the F/A-18 has over 70. Large antenna structures , such as reflecting dishes or planar arrays, are usually housed in fairings or radomes ...manufacturing issues related to incorporating antenna into glass fibre/ ceramic structural armour [24]. A.2.4 USAF The goals of USAF CLAS programs have been...Conformal Load-Bearing Antenna Structure for Australian Defence Force Aircraft Paul J. Callus Air Vehicles Division Defence Science and

  20. Contrasting ontogenetic trajectories for phenolic and terpenoid defences in Eucalyptus froggattii

    PubMed Central

    Goodger, Jason Q. D.; Heskes, Allison M.; Woodrow, Ian E.

    2013-01-01

    Background and Aims Plant defence metabolites are considered costly due to diversion of energy and nutrients away from growth. These costs combined with changes in resource availability and herbivory throughout plant ontogeny are likely to promote changes in defence metabolites. A comprehensive understanding of plant defence strategy requires measurement of lifetime ontogenetic trajectories – a dynamic component largely overlooked in plant defence theories. This study aimed to compare ontogenetic trajectories of foliar phenolics and terpenoids. Phenolics are predicted to be inexpensive to biosynthesize, whereas expensive terpenoids also require specialized, non-photosynthetic secretory structures to avoid autotoxicity. Based on these predicted costs, it is hypothesized that phenolics would be maximally deployed early in ontogeny, whereas terpenoids would be maximally deployed later, once the costs of biosynthesis and foregone photosynthesis could be overcome by enhanced resource acquisition. Methods Leaves were harvested from a family of glasshouse-grown Eucalyptus froggattii seedlings, field-grown saplings and the maternal parent tree, and analysed for total terpenoids and phenolics. Key Results Foliar phenolics were highest in young seedlings and lowest in the adult tree. Indeed the ratio of total phenolics to total terpenoids decreased in a significantly exponential manner with plant ontogeny. Most individual terpene constituents increased with plant ontogeny, but some mono- and sesquiterpenes remained relatively constant or even decreased in concentration as plants aged. Conclusions Plant ontogeny can influence different foliar defence metabolites in directionally opposite ways, and the contrasting trajectories support our hypothesis that phenolics would be maximally deployed earlier than terpenoids. The results highlight the importance of examining ontogenetic trajectories of defence traits when developing and testing theories of plant defence, and

  1. Trade-off among different anti-herbivore defence strategies along an altitudinal gradient.

    PubMed

    Dostálek, Tomáš; Rokaya, Maan Bahadur; Maršík, Petr; Rezek, Jan; Skuhrovec, Jiří; Pavela, Roman; Münzbergová, Zuzana

    2016-01-01

    The type and intensity of plant-herbivore interactions are likely to be altered under climate change as a consequence of differential dispersal rates of plants and their herbivores. Here, we studied variation in herbivore damage on Salvia nubicola in the field and compared its growth and defence strategies against herbivores in controlled conditions using seeds from populations along a broad altitudinal gradient. Our work is one of the first studies to simultaneously measure complex intraspecific variation in plant growth, direct and indirect defences as well as plant tolerance (ability to regrow) as a consequence of herbivore attack simulated by clipping. In the field, we found that plants experienced higher herbivore pressure in lower altitudes. In the greenhouse, plants grown from seeds collected in lower-altitude populations grew better and produced a higher content of phenolic compounds (direct defence) and volatile organic compounds (indirect defence) in response to simulated herbivory. However, there were no differences in tolerance and effect of S. nubicola extracts on the model generalist herbivore Spodoptera littoralis (direct defence) along the altitudinal gradient. Although we found that S. nubicola developed a range of defence strategies, the strategies do not seem to be used simultaneously in all populations even though most of them are correlated with altitudinal gradient. Our finding is in agreement with the current knowledge that co-expression of multiple defences might be costly for a plant, since investment in defensive traits is assumed to reduce the resource availability for growth and reproduction. Our study thus shows the importance of simultaneous study of different defence strategies since understanding these trade-offs could be necessary for detecting the mechanisms by which plants are able to cope with future climate change.

  2. Littoral Infrared Ship Self Defence Technology Studies (Autodefense cotiere infrarouge des navires etudes technologiques)

    DTIC Science & Technology

    2014-05-01

    Modeling Radiometry Ship signature control Surveillance 14. Abstract Task Group Number 51 (RTG-51/SET-088), titled “Littoral Infrared Ship...Centre Renaissancelaan 30, 1000 Bruxelles Armaments Department ITALIE 9-11, Drumul Taberei Street CANADA Centro Gestione Conoscenza Sector 6...Distribučné a Defence R&D Canada informačné stredisko STO Department of National Defence ITALY Demänová 393 305 Rideau Street, 9th Floor Centro Gestione

  3. The CTB1 gene encoding a fungal polyketide synthase is required for cercosporin biosynthesis and fungal virulence of Cercospora nicotianae.

    PubMed

    Choquer, Mathias; Dekkers, Katherine L; Chen, Hui-Qin; Cao, Lihua; Ueng, Peter P; Daub, Margaret E; Chung, Kuang-Ren

    2005-05-01

    Cercosporin is a light-activated, non-host-selective toxin produced by many Cercospora fungal species. In this study, a polyketide synthase gene (CTB1) was functionally identified and molecularly characterized to play a key role in cercosporin biosynthesis by Cercospora nicotianae. We also provide conclusive evidence to confirm the crucial role of cercosporin in fungal pathogenesis. CTB1 encoded a polypeptide with a deduced length of 2,196 amino acids containing a keto synthase (KS), an acyltransferase (AT), a thioesterase/claisen cyclase (TE/CYC), and two acyl carrier protein (ACP) domains, and had high levels of similarity to many fungal type I polyketide synthases. Expression of a 6.8-kb CTB1 transcript was highly regulated by light and medium composition, consistent with the conditions required for cercosporin biosynthesis in cultures. Targeted disruption of CTB1 resulted in the loss of both CTB1 transcript and cercosporin biosynthesis in C. nicotianae. The ctb1-null mutants incited fewer necrotic lesions on inoculated tobacco leaves compared with the wild type. Complementation of ctb1-null mutants with a full-length CTB1 clone restored wild-type levels of cercosporin production as well as the ability to induce lesions on tobacco. Thus, we have demonstrated conclusively that cercosporin is synthesized via a polyketide pathway, and cercosporin is an important virulence factor in C. nicotianae. The results also suggest that strategies that avoid the toxicity of cercosporin will be useful in reduction of disease incidence caused by Cercospora spp.

  4. Synthesis of 'cineole cassette' monoterpenes in Nicotiana section Alatae: gene isolation, expression, functional characterization and phylogenetic analysis.

    PubMed

    Fähnrich, Anke; Brosemann, Anne; Teske, Laura; Neumann, Madeleine; Piechulla, Birgit

    2012-08-01

    The scent bouquets of flowers of Nicotiana species, particularly those of section Alatae, are rich in monoterpenes, including 1,8-cineole, limonene, β-myrcene, α- and β-pinene, sabinene, and α-terpineol. New terpene synthase genes were isolated from flowers of Nicotiana bonariensis, N. forgetiana, N. longiflora, and N. mutabilis. The recombinant enzymes synthesize simultaneously the characteristic 'cineole cassette' monoterpenes with 1,8-cineole as the dominant volatile product. Interestingly, amino acid sequence comparison and phylogenetic tree construction clustered the newly isolated cineole synthases (CIN) of section Alatae together with the catalytically similar CIN of N. suaveolens of section Suaveolentes, thus suggesting a common ancestor. These CIN genes of N. bonariensis, N. forgetiana, N. longiflora, and N. mutabilis are distinct from the terpineol synthases (TERs) of the taxonomically related N. alata and N. langsdorfii (both Alatae), thus indicating gene diversification of monoterpene synthases in section Alatae. Furthermore, the presence of CINs in species of the American section Alatae supports the hypothesis that one parent of the Australian section Suaveolentes was a member of the present section Alatae. Amino acid sequences of the Nicotiana CINs and TERs were compared to identify relevant amino acids of the cyclization reaction from α-terpineol to 1,8-cineole.

  5. An overview of the Defence Research Agency photovoltaic programme

    NASA Technical Reports Server (NTRS)

    Goodbody, C.; Davies, M. A. H.

    1993-01-01

    The Defense Research Agency (DRA) has been active in the photovoltaic field since the early 1960's, then as the Royal Aircraft Establishment (RAE). The early work was aimed at developing silicon cells, solar panels, and light-weight flexible arrays in support of the 'UK' and 'X' series of British scientific and technology satellites, for which the RAE was either the design authority or technical advisor. The X3 satellite - Prospero, launched in 1971 test flew 50 micron wrap-round silicon cells. The X4 satellite - Miranda, launched in 1974 test flew a deployable flexible silicon array which was developed at the DRA. During this period an extensive range of test equipment was developed which was maintained, modernized, and extended to date. Following a period of reduced activity in the late 1970's and early 1980's the current program evolved. The programs that have been undertaken since 1983 are briefly summarized. These range from various cell developments, new types of coverglasses, flight experiments, radiation testing, primary cell calibration, and environmental testing. The current photovoltaic program is mainly funded by the UK Ministry of Defence and by the Department of Trade and Industry through the British National Space Center (BNSC). The program is aimed at research and development, both internally and with industry, to meet the customer's technical objectives and requirements and to provide them with technical advice. The facilities are also being used on contract work for various national and international organizations.

  6. Cold defence responses: the role of oxidative stress.

    PubMed

    Blagojevic, Dusko P; Grubor-Lajsic, Gordana N; Spasic, Mihajlo B

    2011-01-01

    Low temperatures provoke increased production of heat accompanied by increased respiration, oxygen consumption and the production of partially reduced oxygen species called ROS. ROS induce different forms of cellular oxidative damage, disturb the redox state and can change the activity of several metabolic enzymes. Organisms have developed a functionally connected set of anti-oxidant enzymes and low molecular mass compounds (together termed the ADS) that metabolise primary ROS. If ROS production within cells overwhelms the ADS, oxidative damage arises and oxidative stress can occur. Short-term cold exposure in endotherms leads to oxidative stress. As cold exposure persists organisms develop adaptive changes toward reducing ROS production and increasing the ADS. In contrast, heterotherms and ectotherms as a normal part of their over-wintering strategy slow down metabolism, oxygen consumption and subsequently cause ROS production. Increased baseline activity of key anti-oxidant enzymes as well as 'secondary' enzymatic defence and/or glutathione levels in preparation for a putative oxidative stressful situation arising from tissue re-oxygenation seems to be the preferred evolutionary adaptation of such animals exposed to low environmental temperatures.

  7. Limiting immunopathology: Interaction between carotenoids and enzymatic antioxidant defences.

    PubMed

    Babin, A; Saciat, C; Teixeira, M; Troussard, J-P; Motreuil, S; Moreau, J; Moret, Y

    2015-04-01

    The release of reactive oxygen and nitrogen species (ROS and RNS) during the inflammatory response generates damages to host tissues, referred to as immunopathology, and is an important factor in ecological immunology. The integrated antioxidant system, comprising endogenous antioxidant enzymes (e.g. superoxide dismutase SOD, and catalase CAT) and dietary antioxidants (e.g. carotenoids), helps to cope with immune-mediated oxidative stress. Crustaceans store large amounts of dietary carotenoids for yet unclear reasons. While being immunostimulants and antioxidants, the interaction of these pigments with antioxidant enzymes remains unclear. Here, we tested the interaction between dietary supplementation with carotenoids and immune challenge on immune defences and the activity of the antioxidant enzymes SOD and CAT, in the amphipod crustacean Gammarus pulex. Dietary supplementation increased the concentrations of circulating carotenoids and haemocytes in the haemolymph, while the immune response induced the consumption of circulating carotenoids and a drop of haemocyte density. Interestingly, supplemented gammarids exhibited down-regulated SOD activity but high CAT activity compared to control ones. Our study reveals specific interactions of dietary carotenoids with endogenous antioxidant enzymes, and further underlines the potential importance of carotenoids in the evolution of immunity and/or of antioxidant mechanisms in crustaceans.

  8. Thermal Imaging And Its Application In Defence Systems

    NASA Astrophysics Data System (ADS)

    Akula, Aparna; Ghosh, Ripul; Sardana, H. K.

    2011-10-01

    Thermal imaging is a boon to the armed forces namely army, navy and airforce because of its day night working capability and ability to perform well in all weather conditions. Thermal detectors capture the infrared radiation emitted by all objects above absolute zero temperature. The temperature variations of the captured scene are represented as a thermogram. With the advent of infrared detector technology, the bulky cooled thermal detectors having moving parts and demanding cryogenic temperatures have transformed into small and less expensive uncooled microbolometers having no moving parts, thereby making systems more rugged requiring less maintenance. Thermal imaging due to its various advantages has a large number of applications in military and defence. It is popularly used by the army and navy for border surveillance and law enforcement. It is also used in ship collision avoidance and guidance systems. In the aviation industry it has greatly mitigated the risks of flying in low light and night conditions. They are widely used in military aviation to identify, locate and target the enemy forces. Recently, they are also being incorporated in civil aviation for health monitoring of aircrafts.

  9. Faba bean forisomes can function in defence against generalist aphids.

    PubMed

    Medina-Ortega, Karla J; Walker, Gregory P

    2015-06-01

    Phloem sieve elements have shut-off mechanisms that prevent loss of nutrient-rich phloem sap when the phloem is damaged. Some phloem proteins such as the proteins that form forisomes in legume sieve elements are one such mechanism and in response to damage, they instantly form occlusions that stop the flow of sap. It has long been hypothesized that one function of phloem proteins is defence against phloem sap-feeding insects such as aphids. This study provides the first experimental evidence that aphid feeding can induce phloem protein occlusion and that the aphid-induced occlusions inhibit phloem sap ingestion. The great majority of phloem penetrations in Vicia faba by the generalist aphids Myzus persicae and Macrosiphum euphorbiae triggered forisome occlusion and the aphids eventually withdrew their stylets without ingesting phloem sap. This contrasts starkly with a previous study on the legume-specialist aphid, Acyrthosiphon pisum, where penetration of faba bean sieve elements did not trigger forisome occlusion and the aphids readily ingested phloem sap. Next, forisome occlusion was demonstrated to be the cause of failed phloem ingestion attempts by M. persicae: when occlusion was inhibited by the calcium channel blocker lanthanum, M. persicae readily ingested faba bean phloem sap.

  10. Adrenomedullin and mucosal defence: interaction between host and microorganism.

    PubMed

    Allaker, Robert P; Kapas, Supriya

    2003-04-15

    Many surface epithelial cells express adrenomedullin (AM) and it is postulated that it may have an important protective role. This peptide has many properties in common with other cationic antimicrobial peptides including the human beta-defensins. Antimicrobial activity against members of the human skin, oral, respiratory tract and gastric microflora has been demonstrated. Both pathogenic and commensal strains of bacteria are sensitive; Gram-positive and Gram-negative bacteria being equally susceptible. No activity against the yeast Candida albicans was observed. Minimum inhibitory and minimum bacteriocidal concentrations range from 7.75 x 10(-4) to 12.5 and 0.003 to >25.0 microg ml(-1), respectively. On exposure of oral, skin and gastric epithelial cells to whole cells and culture supernatants from bacteria isolated from these sites an increase in AM peptide and gene expression has been observed. No upregulation was detected with C. albicans. In cultured cells and an animal infection model increased AM peptide and gene expression has been demonstrated using immunohistochemical and in situ hybridization techniques. These collective findings suggest that AM represents a new category of antimicrobial peptide, which contributes to the mucosal host defence system.

  11. Microglial self-defence mediated through GLT-1 and glutathione.

    PubMed

    Persson, Mikael; Rönnbäck, Lars

    2012-01-01

    Glutamate is stored in synaptic vesicles in presynaptic neurons. It is released into the synaptic cleft to provide signalling to postsynaptic neurons. Normally, the astroglial glutamate transporters GLT-1 and GLAST take up glutamate to mediate a high signal-to-noise ratio in the synaptic signalling, and also to prevent excitotoxic effects by glutamate. In astrocytes, glutamate is transformed into glutamine, which is safely transported back to neurons. However, in pathological conditions, such as an ischemia or virus infection, astroglial transporters are down-regulated which could lead to excitotoxicity. Lately, it was shown that even microglia can express glutamate transporters during pathological events. Microglia have two systems for glutamate transport: GLT-1 for transport into the cells and the x (c) (-) system for transport out of the cells. We here review results from our work and others, which demonstrate that microglia in culture express GLT-1, but not GLAST, and transport glutamate from the extracellular space. We also show that TNF-α can induce increased microglial GLT-1 expression, possibly associating the expression with inflammatory systems. Furthermore, glutamate taken up through GLT-1 may be used for direct incorporation into glutathione and to fuel the intracellular glutamate pool to allow cystine uptake through the x (c) (-) system. This can lead to a defence against oxidative stress and have an antiviral function.

  12. Trained immunity: A smart way to enhance innate immune defence.

    PubMed

    van der Meer, Jos W M; Joosten, Leo A B; Riksen, Niels; Netea, Mihai G

    2015-11-01

    The innate arm of the immune system is generally viewed as primitive and non-specific and - in contrast to the adaptive immune arm - not to possess memory. However in plants and invertebrate animals that lack adaptive immunity, innate immunity will exhibit a prolonged enhanced functional state after adequate priming. A similar enhancement of function of the innate immunity has occasionally been described in vertebrates, including humans. Over the past few years we have studied this phenomenon in greater detail and we have coined the term 'Trained (innate) immunity' (TI). TI can be induced by a variety of stimuli, of which we have studied BCG and β-glucan in greater detail. The non-specific protective effects of BCG that have been observed in vaccination studies in the literature are probably due to TI. Monocytes and macrophages are among the main cells of the innate immune arm that can be trained. We have discovered that both BCG (via NOD2 signalling) and β-glucan (via dectin-1) induce epigenetic reprogramming, in particular stable changes in histone trimethylation at H3K4. These epigenetic changes lead to cellular activation, enhanced cytokine production and a change in the metabolic state of the cell with a shift from oxidative phosphorylation to aerobic glycolysis. TI is not only important for host defence and vaccine responses, but most probably also for diseases like atherosclerosis. Modulation of TI is a promising area for new treatments.

  13. Functional small airways defence in symptomless cigarette smokers.

    PubMed Central

    Agnew, J E; Lopez-Vidriero, M T; Pavia, D; Clarke, S W

    1986-01-01

    Smoking induced changes in the secretory cells of bronchiolar epithelium by facilitating secretion of cross linked glycoprotein mucus may influence the efficiency of mucus-cilia coupling. The functional impact on mucociliary transport in small (peripheral) airways has been studied by comparing data on aerosol deposition and clearance from symptomless cigarette smokers (30 tests, 18 subjects) with data from age matched non-smokers (30 tests, 19 subjects). Gamma camera images, assessed in terms of a penetration index comparing peripheral with inner zone deposition, indicated closely similar initial deposition in the two groups. Alveolar deposition, however, assessed in terms of particle retention at 24 hours, was significantly (p less than 0.01) less in the smokers. Given the similarity of initial deposition, this implies that an increased proportion of small conducting airways are protected by mucociliary defence in the smokers' lungs. Clearance from conducting airways of the peripheral zone in tests with relatively high peripheral deposition (14 tests on smokers, and 12 on non-smokers) nevertheless proceeded at the same rate in smokers as in non-smokers. PMID:3787532

  14. An overview of the Defence Research Agency photovoltaic programme

    NASA Astrophysics Data System (ADS)

    Goodbody, C.; Davies, M. A. H.

    1993-05-01

    The Defense Research Agency (DRA) has been active in the photovoltaic field since the early 1960's, then as the Royal Aircraft Establishment (RAE). The early work was aimed at developing silicon cells, solar panels, and light-weight flexible arrays in support of the 'UK' and 'X' series of British scientific and technology satellites, for which the RAE was either the design authority or technical advisor. The X3 satellite - Prospero, launched in 1971 test flew 50 micron wrap-round silicon cells. The X4 satellite - Miranda, launched in 1974 test flew a deployable flexible silicon array which was developed at the DRA. During this period an extensive range of test equipment was developed which was maintained, modernized, and extended to date. Following a period of reduced activity in the late 1970's and early 1980's the current program evolved. The programs that have been undertaken since 1983 are briefly summarized. These range from various cell developments, new types of coverglasses, flight experiments, radiation testing, primary cell calibration, and environmental testing. The current photovoltaic program is mainly funded by the UK Ministry of Defence and by the Department of Trade and Industry through the British National Space Center (BNSC). The program is aimed at research and development, both internally and with industry, to meet the customer's technical objectives and requirements and to provide them with technical advice. The facilities are also being used on contract work for various national and international organizations.

  15. Caterpillar hairs as an anti-parasitoid defence

    NASA Astrophysics Data System (ADS)

    Kageyama, Azusa; Sugiura, Shinji

    2016-10-01

    Caterpillar hairs are thought to act as a physical barrier against natural enemies, including parasitoids. However, very few studies have experimentally demonstrated how hairs protect caterpillars from parasitoid oviposition. To clarify the importance of caterpillar hairs as an anti-parasitoid defence, we observed the generalist endoparasitoid Meteorus pulchricornis (Hymenoptera: Braconidae) attacking both smooth and hairy caterpillars under laboratory conditions. A female Meteorus pulchricornis uses its ovipositor to inject venom and lay a single egg inside host larvae. We placed a smooth Spodoptera litura (Lepidoptera: Noctuidae) caterpillar or a hairy Lymantria dispar japonica (Lepidoptera: Erebidae) caterpillar in front of parasitoid females. We observed that 100 % and 84 % of the parasitoids could successfully stab their ovipositors into the smooth larvae of S. litura and first instars of the hairy caterpillar L. dispar japonica, respectively. However, only 24 % of parasitoids could successfully stab their ovipositors into second-instar L. dispar japonica. A higher rate of successful stabs (94 %) by parasitoids was obtained by cutting the hairs of second instar L. dispar japonica much shorter than the parasitoid ovipositor. The results demonstrate that the long, thick hairs of second and later instars of L. dispar japonica function as a physical barrier against parasitoid oviposition.

  16. The correlated evolution of antipredator defences and brain size in mammals.

    PubMed

    Stankowich, Theodore; Romero, Ashly N

    2017-01-11

    Mammals that possess elaborate antipredator defences such as body armour, spines and quills are usually well protected, intermediate in size, primarily insectivorous and live in simple open environments. The benefits of such defences seem clear and may relax selection on maintaining cognitive abilities that aid in vigilance and predator recognition, and their bearers may accrue extensive production and maintenance costs. Here, in this comparative phylogenetic analysis of measurements of encephalization quotient and morphological defence scores of 647 mammal species representing nearly every order, we found that as lineages evolve stronger defences, they suffer a correlated reduction in encephalization. The only exceptions were those that live in trees-a complex three-dimensional world probably requiring greater cognitive abilities. At the proximate level, because brain tissue is extremely energetically expensive to build, mammals may be trading off spending more on elaborate defences and saving by building less powerful brains. At the ultimate level, having greater defences may also reduce the need for advanced cognitive abilities for constant assessment of environmental predation risk, especially in simple open environments.

  17. Competition induces allelopathy but suppresses growth and anti-herbivore defence in a chemically rich seaweed.

    PubMed

    Rasher, Douglas B; Hay, Mark E

    2014-02-22

    Many seaweeds and terrestrial plants induce chemical defences in response to herbivory, but whether they induce chemical defences against competitors (allelopathy) remains poorly understood. We evaluated whether two tropical seaweeds induce allelopathy in response to competition with a reef-building coral. We also assessed the effects of competition on seaweed growth and seaweed chemical defence against herbivores. Following 8 days of competition with the coral Porites cylindrica, the chemically rich seaweed Galaxaura filamentosa induced increased allelochemicals and became nearly twice as damaging to the coral. However, it also experienced significantly reduced growth and increased palatability to herbivores (because of reduced chemical defences). Under the same conditions, the seaweed Sargassum polycystum did not induce allelopathy and did not experience a change in growth or palatability. This is the first demonstration of induced allelopathy in a seaweed, or of competitors reducing seaweed chemical defences against herbivores. Our results suggest that the chemical ecology of coral-seaweed-herbivore interactions can be complex and nuanced, highlighting the need to incorporate greater ecological complexity into the study of chemical defence.

  18. Defence strategies against a parasitoid wasp in Drosophila: fight or flight?

    PubMed

    Lefèvre, Thierry; de Roode, Jacobus C; Kacsoh, Balint Z; Schlenke, Todd A

    2012-04-23

    Hosts may defend themselves against parasitism through a wide variety of defence mechanisms, but due to finite resources, investment in one defence mechanism may trade-off with investment in another mechanism. We studied resistance strategies against the parasitoid wasp Leptopilina boulardi in two Drosophila species. We found that D. melanogaster had significantly lower physiological resistance against L. boulardi than D. simulans, and hypothesized that D. melanogaster might instead invest more heavily in other forms of defence, such as behavioural defence. We found that when given a choice between clean oviposition sites and sites infested with wasps, both D. melanogaster and D. simulans detected and avoided infested sites, which presumably limits later exposure of their offspring to infection. Unlike D. simulans, however, D. melanogaster laid significantly fewer eggs than controls in the forced presence of wasps. Our findings suggest that D. melanogaster relies more heavily on behavioural avoidance as defence against wasp parasitism than D. simulans, and that this may compensate for a lack of physiological defence.

  19. Parental risk management in relation to offspring defence: bad news for kids

    PubMed Central

    Mahr, Katharina; Riegler, Georg; Hoi, Herbert

    2015-01-01

    Do parents defend their offspring whenever necessary, and do self-sacrificing parents really exist? Studies recognized that parent defence is dynamic, mainly depending on the threat predators pose. In this context, parental risk management should consider the threat to themselves and to their offspring. Consequently, the observed defence should be a composite of both risk components. Surprisingly, no study so far has determined the influence of these two threat components on parental decision rules. In a field experiment, we investigated parental risk taking in relation to the threat posed to themselves and their offspring. To disentangle the two threat components, we examined defence behaviours of parent blue tits Cyanistes caeruleus towards three different predators and during different nestling developmental stages. Nest defence strategies in terms of alarm call intensity and nearest predator approach differed between the three predators. Defence intensity was only partly explained by threat level. Most importantly, parental risk management varied in relation to their own, but not offspring risk. Parent defence investment was independent of nestling risk when parents followed a high-risk strategy. However, parents considered nestling as well as parental risk when following a low-risk strategy. Our findings could have general implications for the economy of risk management and decision-making strategies in living beings, including humans. PMID:25392467

  20. Uncoupling of reactive oxygen species accumulation and defence signalling in the metal hyperaccumulator plant Noccaea caerulescens.

    PubMed

    Fones, Helen N; Eyles, Chris J; Bennett, Mark H; Smith, J Andrew C; Preston, Gail M

    2013-09-01

    The metal hyperaccumulator plant Noccaea caerulescens is protected from disease by the accumulation of high concentrations of metals in its aerial tissues, which are toxic to many pathogens. As these metals can lead to the production of damaging reactive oxygen species (ROS), metal hyperaccumulator plants have developed highly effective ROS tolerance mechanisms, which might quench ROS-based signals. We therefore investigated whether metal accumulation alters defence signalling via ROS in this plant. We studied the effect of zinc (Zn) accumulation by N. caerulescens on pathogen-induced ROS production, salicylic acid accumulation and downstream defence responses, such as callose deposition and pathogenesis-related (PR) gene expression, to the bacterial pathogen Pseudomonas syringae pv. maculicola. The accumulation of Zn caused increased superoxide production in N. caerulescens, but inoculation with P. syringae did not elicit the defensive oxidative burst typical of most plants. Defences dependent on signalling through ROS (callose and PR gene expression) were also modified or absent in N. caerulescens, whereas salicylic acid production in response to infection was retained. These observations suggest that metal hyperaccumulation is incompatible with defence signalling through ROS and that, as metal hyperaccumulation became effective as a form of elemental defence, normal defence responses became progressively uncoupled from ROS signalling in N. caerulescens.

  1. Parental risk management in relation to offspring defence: bad news for kids.

    PubMed

    Mahr, Katharina; Riegler, Georg; Hoi, Herbert

    2015-01-07

    Do parents defend their offspring whenever necessary, and do self-sacrificing parents really exist? Studies recognized that parent defence is dynamic, mainly depending on the threat predators pose. In this context, parental risk management should consider the threat to themselves and to their offspring. Consequently, the observed defence should be a composite of both risk components. Surprisingly, no study so far has determined the influence of these two threat components on parental decision rules. In a field experiment, we investigated parental risk taking in relation to the threat posed to themselves and their offspring. To disentangle the two threat components, we examined defence behaviours of parent blue tits Cyanistes caeruleus towards three different predators and during different nestling developmental stages. Nest defence strategies in terms of alarm call intensity and nearest predator approach differed between the three predators. Defence intensity was only partly explained by threat level. Most importantly, parental risk management varied in relation to their own, but not offspring risk. Parent defence investment was independent of nestling risk when parents followed a high-risk strategy. However, parents considered nestling as well as parental risk when following a low-risk strategy. Our findings could have general implications for the economy of risk management and decision-making strategies in living beings, including humans.

  2. RNA silencing is required for Arabidopsis defence against Verticillium wilt disease

    PubMed Central

    Ellendorff, Ursula; Fradin, Emilie F.; de Jonge, Ronnie; Thomma, Bart P. H. J.

    2009-01-01

    RNA silencing is a conserved mechanism in eukaryotes that plays an important role in various biological processes including regulation of gene expression. RNA silencing also plays a role in genome stability and protects plants against invading nucleic acids such as transgenes and viruses. Recently, RNA silencing has been found to play a role in defence against bacterial plant pathogens in Arabidopsis through modulating host defence responses. In this study, it is shown that gene silencing plays a role in plant defence against multicellular microbial pathogens; vascular fungi belonging to the Verticillium genus. Several components of RNA silencing pathways were tested, of which many were found to affect Verticillium defence. Remarkably, no altered defence towards other fungal pathogens that include Alternaria brassicicola, Botrytis cinerea, and Plectosphaerella cucumerina, but also the vascular pathogen Fusarium oxysporum, was recorded. Since the observed differences in Verticillium susceptibility cannot be explained by notable differences in root architecture, it is speculated that the gene silencing mechanisms affect regulation of Verticillium-specific defence responses. PMID:19098131

  3. RNA silencing is required for Arabidopsis defence against Verticillium wilt disease.

    PubMed

    Ellendorff, Ursula; Fradin, Emilie F; de Jonge, Ronnie; Thomma, Bart P H J

    2009-01-01

    RNA silencing is a conserved mechanism in eukaryotes that plays an important role in various biological processes including regulation of gene expression. RNA silencing also plays a role in genome stability and protects plants against invading nucleic acids such as transgenes and viruses. Recently, RNA silencing has been found to play a role in defence against bacterial plant pathogens in Arabidopsis through modulating host defence responses. In this study, it is shown that gene silencing plays a role in plant defence against multicellular microbial pathogens; vascular fungi belonging to the Verticillium genus. Several components of RNA silencing pathways were tested, of which many were found to affect Verticillium defence. Remarkably, no altered defence towards other fungal pathogens that include Alternaria brassicicola, Botrytis cinerea, and Plectosphaerella cucumerina, but also the vascular pathogen Fusarium oxysporum, was recorded. Since the observed differences in Verticillium susceptibility cannot be explained by notable differences in root architecture, it is speculated that the gene silencing mechanisms affect regulation of Verticillium-specific defence responses.

  4. Comparing systemic defence-related gene expression changes upon migratory and sedentary nematode attack in rice.

    PubMed

    Kyndt, T; Nahar, K; Haegeman, A; De Vleesschauwer, D; Höfte, M; Gheysen, G

    2012-03-01

    Complex defence signalling pathways, controlled by different hormones, are known to be involved in the reaction of plants to a wide range of biotic and abiotic stress factors. Here, we studied the differential expression of genes involved in stress and defence responses in systemic tissue of rice infected with the root knot nematode (RKN) Meloidogyne graminicola and the migratory root rot nematode Hirschmanniella oryzae, two agronomically important rice pathogens with very different lifestyles. qRT-PCR revealed that all investigated systemic tissues had significantly lower expression of isochorismate synthase, a key enzyme for salicylic acid production involved in basal defence and systemic acquired resistance. The systemic defence response upon migratory nematode infection was remarkably similar to fungal rice blast infection. Almost all investigated defence-related genes were up-regulated in rice shoots 3 days after root rot nematode attack, including the phenylpropanoid pathway, ethylene pathway and PR genes, but many of which were suppressed at 7 dpi. Systemic shoot tissue of RKN-infected plants showed similar attenuation of expression of almost all studied genes already at 3 dpi, with clear attenuation of the ethylene pathway and methyl jasmonate biosynthesis. These results provide an interesting starting point for further studies to elucidate how nematodes are able to suppress systemic plant defence mechanisms and the effect in multitrophic interactions.

  5. Hijacking common mycorrhizal networks for herbivore-induced defence signal transfer between tomato plants

    PubMed Central

    Song, Yuan Yuan; Ye, Mao; Li, Chuanyou; He, Xinhua; Zhu-Salzman, Keyan; Wang, Rui Long; Su, Yi Juan; Luo, Shi Ming; Zeng, Ren Sen

    2014-01-01

    Common mycorrhizal networks (CMNs) link multiple plants together. We hypothesized that CMNs can serve as an underground conduit for transferring herbivore-induced defence signals. We established CMN between two tomato plants in pots with mycorrhizal fungus Funneliformis mosseae, challenged a ‘donor' plant with caterpillar Spodoptera litura, and investigated defence responses and insect resistance in neighbouring CMN-connected ‘receiver' plants. After CMN establishment caterpillar infestation on ‘donor' plant led to increased insect resistance and activities of putative defensive enzymes, induction of defence-related genes and activation of jasmonate (JA) pathway in the ‘receiver' plant. However, use of a JA biosynthesis defective mutant spr2 as ‘donor' plants resulted in no induction of defence responses and no change in insect resistance in ‘receiver' plants, suggesting that JA signalling is required for CMN-mediated interplant communication. These results indicate that plants are able to hijack CMNs for herbivore-induced defence signal transfer and interplant defence communication. PMID:24468912

  6. Metabolic engineering of medium-chain fatty acid biosynthesis in Nicotiana benthamiana plant leaf lipids

    PubMed Central

    Reynolds, Kyle B.; Taylor, Matthew C.; Zhou, Xue-Rong; Vanhercke, Thomas; Wood, Craig C.; Blanchard, Christopher L.; Singh, Surinder P.; Petrie, James R.

    2015-01-01

    Various research groups are investigating the production of oil in non-seed biomass such as leaves. Recently, high levels of oil accumulation have been achieved in plant biomass using a combination of biotechnological approaches which also resulted in significant changes to the fatty acid composition of the leaf oil. In this study, we were interested to determine whether medium-chain fatty acids (MCFA) could be accumulated in leaf oil. MCFA are an ideal feedstock for biodiesel and a range of oleochemical products including lubricants, coatings, and detergents. In this study, we explore the synthesis, accumulation, and glycerolipid head-group distribution of MCFA in leaves of Nicotiana benthamiana after transient transgenic expression of C12:0-, C14:0-, and C16:0-ACP thioesterase genes. We demonstrate that the production of these MCFA in leaf is increased by the co-expression of the WRINKLED1 (WRI1) transcription factor, with the lysophosphatidic acid acyltransferase (LPAAT) from Cocos nucifera being required for the assembly of tri-MCFA TAG species. We also demonstrate that the newly-produced MCFA are incorporated into the triacylglycerol of leaves in which WRI1 + diacylglycerol acyltransferase1 (DGAT1) genes are co-expressed for increased oil accumulation. PMID:25852716

  7. Zoospore density-dependent behaviors of Phytophthora nicotianae are autoregulated by extracellular products.

    PubMed

    Kong, Ping; Hong, Chuanxue

    2010-07-01

    Phytophthora species are destructive fungus-like plant pathogens that use asexual single-celled flagellate zoospores for dispersal and plant infection. Many of the zoospore behaviors are density-dependent although the underlying mechanisms are poorly understood. Here, we use P. nicotianae as a model and demonstrate autoregulation of some zoospore behaviors using signal molecules that zoospores release into the environment. Specifically, zoospore aggregation, plant targeting, and infection required or were enhanced by threshold concentrations of these signal molecules. Below the threshold concentration, zoospores did not aggregate and move toward a cauline leaf of Arabidopsis thaliana (Col-0) and failed to individually attack annual vinca (Catharanthus roseus cv. Little Bright Eye). These processes were reversed when supplemented with zoospore-free fluid (ZFF) prepared from a zoospore suspension above threshold densities but not with calcium chloride at a concentration equivalent to extracellular Ca(2+) in ZFF. These results suggest that Ca(2+) is not a primary signal molecule regulating these communal behaviors. Zoospores coordinated their communal behaviors by releasing, detecting, and responding to signal molecules. This chemical communication mechanism raises the possibility that Phytophthora plant infection may not depend solely on zoospore number in the real world. Single zoospore infection may take place if it is signaled by a common molecule available in the environment which contributes to the destructiveness of these plant pathogens.

  8. The effect of intermittent dosing of Nicotiana glauca on teratogenesis in goats.

    PubMed

    Welch, K D; Panter, K E; Lee, S T; Gardner, D R

    2015-01-01

    Sustained inhibition of fetal movement in livestock species, induced by several poisonous plants, can result in numerous skeletal-contracture malformations. Lupines are responsible for a condition in cattle referred to as "crooked calf syndrome" that occurs when pregnant cattle graze teratogenic lupines. Similar malformations are also seen in animals poisoned by Conium maculatum (coniine) and Nicotiana glauca (anabasine). A proposed management strategy to limit these types of birth defects includes utilizing an intermittent grazing schedule to allow short durations of grazing lupine-infested areas interrupted by movement to a lupine-free pasture. The objective of this study was to use a goat model to determine if an intermittent schedule of five continuous days on treatment followed by two days off treatment would be sufficient to decrease, or prevent, the incidence of anabasine-induced malformations. The data from this study suggest that, for N. glauca in goats, the intermittent grazing program of five days exposure with two days of non-exposure is insufficient to prevent significant skeletal malformations from occurring. However, this study did demonstrate an inverse relationship between the amount of serum anabasine in the dam and the extent of fetal movement.

  9. Transient Expression of Candidatus Liberibacter Asiaticus Effector Induces Cell Death in Nicotiana benthamiana

    PubMed Central

    Pitino, Marco; Armstrong, Cheryl M.; Cano, Liliana M.; Duan, Yongping

    2016-01-01

    Candidatus Liberibacter asiaticus “Las” is a phloem-limited bacterial plant pathogen, and the most prevalent species of Liberibacter associated with citrus huanglongbing (HLB), a devastating disease of citrus worldwide. Although, the complete sequence of the Las genome provides the basis for studying functional genomics of Las and molecular mechanisms of Las-plant interactions, the functional characterization of Las effectors remains a slow process since remains to be cultured. Like other plant pathogens, Las may deliver effector proteins into host cells and modulate a variety of host cellular functions for their infection progression. In this study, we identified 16 putative Las effectors via bioinformatics, and transiently expressed them in Nicotiana benthamiana. Diverse subcellular localization with different shapes and aggregation patterns of the effector candidates were revealed by UV- microscopy after transient expression in leaf tissue. Intriguingly, one of the 16 candidates, Las5315mp (mature protein), was localized in the chloroplast and induced cell death at 3 days post inoculation (dpi) in N. benthamiana. Moreover, Las5315mp induced strong callose deposition in plant cells. This study provides new insights into the localizations and potential roles of these Las effectors in planta. PMID:27458468

  10. Evaluation of hepatoprotective effect of Pistacia lentiscus, Phillyrea latifolia and Nicotiana glauca.

    PubMed

    Janakat, Sana; Al-Merie, Hela

    2002-11-01

    The hepatoprotective effect of the boiled and non-boiled aqueous extracts of Pistacia lentiscus, Phillyrea latifolia, and Nicotiana glauca, that are alleged to be effective in the treatment of jaundice in Jordanian folk medicine, was evaluated in vivo using carbon tetrachloride (CCl(4)) intoxicated rats as an experimental model. Plant extracts were administrated orally at a dose of 4 ml/kg body weight, containing various amounts of solid matter. Only total serum bilirubin level was reduced by treatment with non-boiled aqueous extract of N. glauca leaves, while the boiled and non-boiled aqueous extracts of the N. glauca flowers were non effective. Bilirubin level and the activity of alkaline phosphatase (ALP) were both reduced upon treatment with boiled aqueous extract of P. latifolia without reducing the activity of alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Aqueous extract of P. lentiscus (both boiled and non-boiled) showed marked antihepatotoxic activity against CCl(4) by reducing the activity of the three enzymes and the level of bilirubin. The effect of the non-boiled aqueous extract was more pronounced than that of the boiled extract.

  11. Oligomerization status influences subcellular deposition and glycosylation of recombinant butyrylcholinesterase in Nicotiana benthamiana

    PubMed Central

    Schneider, Jeannine D; Marillonnet, Sylvestre; Castilho, Alexandra; Gruber, Clemens; Werner, Stefan; Mach, Lukas; Klimyuk, Victor; Mor, Tsafrir S; Steinkellner, Herta

    2014-01-01

    Plants have a proven track record for the expression of biopharmaceutically interesting proteins. Importantly, plants and mammals share a highly conserved secretory pathway that allows similar folding, assembly and posttranslational modifications of proteins. Human butyrylcholinesterase (BChE) is a highly sialylated, tetrameric serum protein, investigated as a bioscavenger for organophosphorous nerve agents. Expression of recombinant BChE (rBChE) in Nicotiana benthamiana results in accumulation of both monomers as well as assembled oligomers. In particular, we show here that co-expression of BChE with a novel gene-stacking vector, carrying six mammalian genes necessary for in planta protein sialylation, resulted in the generation of rBChE decorated with sialylated N-glycans. The N-glycosylation profile of monomeric rBChE secreted to the apoplast largely resembles the plasma-derived orthologue. In contrast, rBChE purified from total soluble protein extracts was decorated with a significant portion of ER-typical oligomannosidic structures. Biochemical analyses and live-cell imaging experiments indicated that impaired N-glycan processing is due to aberrant deposition of rBChE oligomers in the endoplasmic reticulum or endoplasmic-reticulum-derived compartments. In summary, we show the assembly of rBChE multimers, however, also points to the need for in-depth studies to explain the unexpected subcellular targeting of oligomeric BChE in plants. PMID:24618259

  12. Unpredictability of nectar nicotine promotes outcrossing by hummingbirds in Nicotiana attenuata.

    PubMed

    Kessler, Danny; Bhattacharya, Samik; Diezel, Celia; Rothe, Eva; Gase, Klaus; Schöttner, Matthias; Baldwin, Ian T

    2012-08-01

    Many plants use sophisticated strategies to maximize their reproductive success via outcrossing. Nicotiana attenuata flowers produce nectar with nicotine at concentrations that are repellent to hummingbirds, increasing the number of flowers visited per plant. In choice tests using native hummingbirds, we show that these important pollinators learn to tolerate high-nicotine nectar but prefer low-nicotine nectar, and show no signs of nicotine addiction. Nectar nicotine concentrations, unlike those of other vegetative tissues, are unpredictably variable among flowers, not only among populations, but also within populations, and even among flowers within an inflorescence. To evaluate whether variations in nectar nicotine concentrations increase outcrossing, polymorphic microsatellite markers, optimized to evaluate paternity in native N. attenuata populations, were used to compare outcrossing in plants silenced for expression of a biosynthetic gene for nicotine production (Napmt1/2) and in control empty vector plants, which were antherectomized and transplanted into native populations. When only exposed to hummingbird pollinators, seeds produced by flowers with nicotine in their nectar had a greater number of genetically different sires, compared to seeds from nicotine-free flowers. As the variation in nectar nicotine levels among flowers in an inflorescence decreased in N. attenuata plants silenced in various combinations of three Dicer-like (DCL) proteins, small RNAs are probably involved in the unpredictable variation in nectar nicotine levels within a plant.

  13. Insect herbivory elicits genome-wide alternative splicing responses in Nicotiana attenuata.

    PubMed

    Ling, Zhihao; Zhou, Wenwu; Baldwin, Ian T; Xu, Shuqing

    2015-10-01

    Changes in gene expression and alternative splicing (AS) are involved in many responses to abiotic and biotic stresses in eukaryotic organisms. In response to attack and oviposition by insect herbivores, plants elicit rapid changes in gene expression which are essential for the activation of plant defenses; however, the herbivory-induced changes in AS remain unstudied. Using mRNA sequencing, we performed a genome-wide analysis on tobacco hornworm (Manduca sexta) feeding-induced AS in both leaves and roots of Nicotiana attenuata. Feeding by M. sexta for 5 h reduced total AS events by 7.3% in leaves but increased them in roots by 8.0% and significantly changed AS patterns in leaves and roots of existing AS genes. Feeding by M. sexta also resulted in increased (in roots) and decreased (in leaves) transcript levels of the serine/arginine-rich (SR) proteins that are involved in the AS machinery of plants and induced changes in SR gene expression that were jasmonic acid (JA)-independent in leaves but JA-dependent in roots. Changes in AS and gene expression elicited by M. sexta feeding were regulated independently in both tissues. This study provides genome-wide evidence that insect herbivory induces changes not only in the levels of gene expression but also in their splicing, which might contribute to defense against and/or tolerance of herbivory.

  14. Imaging viral infection: studies on Nicotiana benthamiana plants infected with the pepper mild mottle tobamovirus.

    PubMed

    Pérez-Bueno, María Luisa; Ciscato, Massimo; VandeVen, Martin; García-Luque, Isabel; Valcke, Roland; Barón, Matilde

    2006-11-01

    We have studied by kinetic Chl-fluorescence imaging (Chl-FI) Nicotiana benthamiana plants infected with the Italian strain of the pepper mild mottle tobamovirus (PMMoV-I). We have mapped leaf photosynthesis at different points of the fluorescence induction curve as well as at different post-infection times. Images of different fluorescence parameters were obtained to investigate which one could discriminate control from infected leaves in the absence of symptoms. The non-photochemical quenching (NPQ) of excess energy in photosystem II (PSII) seems to be the most adequate chlorophyll fluorescence parameter to assess the effect of tobamoviral infection on the chloroplast. Non-symptomatic mature leaves from inoculated plants displayed a very characteristic time-varying NPQ pattern. In addition, a correlation between NPQ amplification and virus localization by tissue-print was found, suggesting that an increase in the local NPQ values is associated with the areas invaded by the pathogen. Changes in chloroplast ultrastructure in non-symptomatic leaf areas showing different NPQ levels were also investigated. A gradient of ultrastructural modifications was observed among the different areas.

  15. Changes in cytokinins are sufficient to alter developmental patterns of defense metabolites in Nicotiana attenuata.

    PubMed

    Brütting, Christoph; Schäfer, Martin; Vanková, Radomíra; Gase, Klaus; Baldwin, Ian T; Meldau, Stefan

    2017-01-01

    Plant defense metabolites are well known to be regulated developmentally. The optimal defense (OD) theory posits that a tssue's fitness values and probability of attack should determine defense metabolite allocations. Young leaves are expected to provide a larger fitness value to the plant, and therefore their defense allocations should be higher when compared with older leaves. The mechanisms that coordinate development with defense remain unknown and frequently confound tests of the OD theory predictions. Here we demonstrate that cytokinins (CKs) modulate ontogeny-dependent defenses in Nicotiana attenuata. We found that leaf CK levels highly correlate with inducible defense expressions with high levels in young and low levels in older leaves. We genetically manipulated the developmental patterns of two different CK classes by using senescence- and chemically inducible expression of CK biosynthesis genes. Genetically modifying the levels of different CKs in leaves was sufficient to alter ontogenic patterns of defense metabolites. We conclude that the developmental regulation of growth hormones that include CKs plays central roles in connecting development with defense and therefore in establishing optimal patterns of defense allocation in plants.

  16. Silencing of the FRO1 gene and its effects on iron partition in Nicotiana benthamiana.

    PubMed

    Gama, Florinda; Saavedra, Teresa; Dandlen, Susana; de Varennes, Amarilis; Correia, Pedro J; Pestana, Maribela; Nolasco, Gustavo

    2017-03-06

    To evaluate the dynamic role of the ferric-chelate reductase enzyme (FCR) and to identify possible pathways of regulation of its activity in different plant organs an investigation was conducted by virus-induced gene silencing (VIGS) using tobacco rattle virus (TRV) to silence the ferric reductase oxidase gene (FRO1) that encodes the FCR enzyme. Half of Nicotiana benthamiana plants received the VIGS vector and the rest remained as control. Four treatments were imposed: two levels of Fe in the nutrient solution (0 or 2.5 μM of Fe), each one with silenced or non-silenced (VIGS-0; VIGS-2.5) plants. Plants grown without iron (0; VIGS-0) developed typical symptoms of iron deficiency in the youngest leaves. To prove that FRO1 silencing had occurred, resupply of Fe (R) was done by adding 2.5 μM of Fe to the nutrient solution in a subset of chlorotic plants (0-R; VIGS-R). Twelve days after resupply, 0-R plants had recovered from Fe deficiency while plants containing the VIGS vector (VIGS-R) remained chlorotic and both FRO1 gene expression and FCR activity were considerably reduced, consequently preventing Fe uptake. With the VIGS technique we were able to silence the FRO1 gene in N. benthamiana and point out its importance in chlorophyll synthesis and Fe partition.

  17. Potato virus X movement in Nicotiana benthamiana: new details revealed by chimeric coat protein variants.

    PubMed

    Betti, Camilla; Lico, Chiara; Maffi, Dario; D'Angeli, Simone; Altamura, Maria Maddalena; Benvenuto, Eugenio; Faoro, Franco; Baschieri, Selene

    2012-02-01

    Potato virus X coat protein is necessary for both cell-to-cell and phloem transfer, but it has not been clarified definitively whether it is needed in both movement phases solely as a component of the assembled particles or also of differently structured ribonucleoprotein complexes. To clarify this issue, we studied the infection progression of a mutant carrying an N-terminal deletion of the coat protein, which was used to construct chimeric virus particles displaying peptides selectively affecting phloem transfer or cell-to-cell movement. Nicotiana benthamiana plants inoculated with expression vectors encoding the wild-type, mutant and chimeric viral genomes were examined by microscopy techniques. These experiments showed that coat protein-peptide fusions promoting cell-to-cell transfer only were not competent for virion assembly, whereas long-distance movement was possible only for coat proteins compatible with virus particle formation. Moreover, the ability of the assembled PVX to enter and persist into developing xylem elements was revealed here for the first time.

  18. Constraints to herbivore-induced systemic responses: bidirectional signaling along orthostichies in Nicotiana attenuata.

    PubMed

    Schittko, Ursula; Baldwin, Ian T

    2003-03-01

    We investigated the impact of leaf vascular connections on systemically transmitted herbivore-induced gene expression in Nicotiana attenuata. Although systemic signaling is clearly associated with the plant vascular system, few studies consider vascular architecture when measuring systemically induced defenses. N. attenuata is a plant with dispersed phyllotaxis approximating 3/8 in the rosette stage of growth. We mimicked Manduca sexta herbivory by introducing larval regurgitant to wounds produced with a standardized continuous mechanical wounding and investigated mRNA accumulation of genes. Herbivory in N. attenuata induces the expression of genes coding for a proteinase inhibitor protein (PI), threonine deaminase (TD, EC 4.3.1.19), a luminal-binding protein (BiP), and an alpha-dioxygenase (alpha-DOX). We measured the systemic response of sink leaves when orthostichous (growing at an angular distance of 0 degrees) source leaves were treated, and vice versa, and compared it to the systemic response of leaves growing at the maximum angular distance of 180 degrees. Vascular architecture clearly controlled the intensity of systemic mRNA accumulation within the 4-hr time frame of the experiment. In addition, we found signal translocation to be bidirectional, travelling from source to sink as well as from sink to source leaves, which argues against a phloem-based assimilate-linked signal identity.

  19. Salivary proteins of spider mites suppress defenses in Nicotiana benthamiana and promote mite reproduction.

    PubMed

    Villarroel, Carlos A; Jonckheere, Wim; Alba, Juan M; Glas, Joris J; Dermauw, Wannes; Haring, Michel A; Van Leeuwen, Thomas; Schuurink, Robert C; Kant, Merijn R

    2016-04-01

    Spider mites (Tetranychidae sp.) are widely occurring arthropod pests on cultivated plants. Feeding by the two-spotted spider mite T. urticae, a generalist herbivore, induces a defense response in plants that mainly depends on the phytohormones jasmonic acid and salicylic acid (SA). On tomato (Solanum lycopersicum), however, certain genotypes of T. urticae and the specialist species T. evansi were found to suppress these defenses. This phenomenon occurs downstream of phytohormone accumulation via an unknown mechanism. We investigated if spider mites possess effector-like proteins in their saliva that can account for this defense suppression. First we performed an in silico prediction of the T. urticae and the T. evansi secretomes, and subsequently generated a short list of candidate effectors based on additional selection criteria such as life stage-specific expression and salivary gland expression via whole mount in situ hybridization. We picked the top five most promising protein families and then expressed representatives in Nicotiana benthamiana using Agrobacterium tumefaciens transient expression assays to assess their effect on plant defenses. Four proteins from two families suppressed defenses downstream of the phytohormone SA. Furthermore, T. urticae performance on N. benthamiana improved in response to transient expression of three of these proteins and this improvement was similar to that of mites feeding on the tomato SA accumulation mutant nahG. Our results suggest that both generalist and specialist plant-eating mite species are sensitive to SA defenses but secrete proteins via their saliva to reduce the negative effects of these defenses.

  20. Identification of photoperiod-regulated gene in soybean and functional analysis in Nicotiana benthamiana.

    PubMed

    Ai-Hua, Sha; Yin-Hua, Chen; Zhi-Hui, Shan; Xiao-Juan, Zhang; Xue-Jun, Wu; De-Zheng, Qiu; Xin-An, Zhou

    2014-04-01

    Soybean (Glycine max) is a short-day crop and the photoperiod is a crucial factor regulating its flowering time. To investigate the molecular mechanism controlling the flowering time by photoperiod in soybean, cDNA-amplified fragment length polymorphism (cDNA-AFLP) was used to identify photoperiod-regulated genes in leaves of soybean growing under short-day length, neutral photoperiod and long-day length. A total of 36 transcript-derived fragments (TDFs) were identified to be regulated by photoperiod. Among them, 26 TDFs were homologues of genes with known function. These genes are involved in secondary metabolism, cellular metabolism, cell wall components metabolism, ion transport and hormone signalling. Silencing of the homologue genes in Nicotiana benthamiana for 14 TDFs was conducted by virus-induced gene silencing. The flowering time was delayed by silencing of the genes encoding rhodanese and 40S ribosomal protein S4 (RPS4). The results indicated that rhodanese and RPS4 probably play important roles in regulating flowering time.

  1. Metabolic engineering of Nicotiana benthamiana for the increased production of taxadiene.

    PubMed

    Hasan, Md Mohidul; Kim, Hyun-Soon; Jeon, Jae-Heung; Kim, Sung Hong; Moon, BoKyung; Song, Jai-Young; Shim, Sang Hee; Baek, Kwang-Hyun

    2014-06-01

    We report the production of taxadiene by transformation of N. benthamiana with a taxadiene synthase gene. The production was significantly increased by an elicitor treatment or metabolic pathway shunting. Paclitaxel (Taxol(®)) was first isolated from the bark of the pacific yew tree as an anticancer agent and has been used extensively to treat various types of cancer. Taxadiene, the first committed product of paclitaxel synthesis is cyclized from geranylgeranyl diphosphate (GGPP), and further complex hydroxylation and acylation processes of the unique taxane core skeleton produce paclitaxel. To accomplish de novo production of taxadiene, we transformed Nicotiana benthamiana with a taxadiene synthase (TS) gene. The introduced TS gene under the transcriptional control of the CaMV 35S promoter was constitutively expressed in N. benthamiana, and the de novo production of taxadiene was confirmed by mass spectroscopy profiling. Transformed N. benthamiana homozygous lines produced 11-27 μg taxadiene/g of dry weight. The highest taxadiene production line TSS-8 was further treated with an elicitor, methyl jasmonate, and metabolic pathway shunting by suppression of the phytoene synthase gene expression which resulted in accumulation of increased taxadiene accumulation by 1.4- or 1.9-fold, respectively. In summary, we report that the production of taxadiene in N. benthamiana was possible by the ectopic expression of the TS gene, and higher accumulation of taxadiene could be achieved by elicitor treatment or metabolic pathway shunting of the terpenoid pathway.

  2. The alternative respiratory pathway is involved in brassinosteroid-induced environmental stress tolerance in Nicotiana benthamiana

    PubMed Central

    Deng, Xing-Guang; Zhu, Tong; Zhang, Da-Wei; Lin, Hong-Hui

    2015-01-01

    Brassinosteroids (BRs), plant steroid hormones, play essential roles in modulating cell elongation, vascular differentiation, senescence, and stress responses. However, the mechanisms by which BRs regulate plant mitochondria and resistance to abiotic stress remain largely unclear. Mitochondrial alternative oxidase (AOX) is involved in the plant response to a variety of environmental stresses. In this report, the role of AOX in BR-induced tolerance against cold, polyethylene glycol (PEG), and high-light stresses was investigated. Exogenous applied brassinolide (BL, the most active BR) induced, while brassinazole (BRZ, a BR biosynthesis inhibitor) reduced alternative respiration and AOX1 expression in Nicotiana benthamiana. Chemical scavenging of H2O2 and virus-induced gene silencing (VIGS) of NbRBOHB compromised the BR-induced alternative respiratory pathway, and this result was further confirmed by NbAOX1 promoter analysis. Furthermore, inhibition of AOX activity by chemical treatment or a VIGS-based approach decreased plant resistance to environmental stresses and compromised BR-induced stress tolerance. Taken together, our results indicate that BR-induced AOX capability might contribute to the avoidance of superfluous reactive oxygen species accumulation and the protection of photosystems under stress conditions in N. benthamiana. PMID:26175355

  3. Detection of Nicotiana DNA in Tobacco Products Using a Novel Multiplex Real-Time PCR Assay.

    PubMed

    Korchinski, Katie L; Land, Adrian D; Craft, David L; Brzezinski, Jennifer L

    2016-07-01

    Establishing that a product contains tobacco is a requirement for the U.S. Food and Drug Administration's regulation and/or prosecution of tobacco products. Therefore, a multiplex real-time PCR method was designed to determine if Nicotiana (tobacco) DNA is present in tobacco products. The PCR method simultaneously amplifies a 73 bp fragment of the cytochrome P450 monoxygenase CYP82E4 gene and 66 bp fragment in the nia-1 gene for nitrate reductase, which are detected using dual-labeled TaqMan probes. The assay is capable of detecting approximately 7.8 pg purified tobacco DNA, with a similar sensitivity for either gene target while incorporating an internal positive control (IPC). DNA was extracted from prepared tobacco products-including chewing tobacco, pipe tobacco, and snuff-or from the cut fill (no wrapper) of cigarettes and cigars. Of the 13 products analyzed, 12 were positive for both tobacco-specific markers and the IPC. DNA was also extracted from the fill of five varieties of herbal cigarettes, which were negative for both tobacco-specific gene targets and positive for the IPC. Our method expands on current assays by introducing a multiplex reaction, targeting two sequences in two different genes of interest, incorporating an IPC into the reaction, and lowering the LOD and LOQ while increasing the efficiency of the PCR.

  4. Optimization of Engineered Production of the Glucoraphanin Precursor Dihomomethionine in Nicotiana benthamiana

    PubMed Central

    Crocoll, Christoph; Mirza, Nadia; Reichelt, Michael; Gershenzon, Jonathan; Halkier, Barbara Ann

    2016-01-01

    Glucosinolates are natural products characteristic of the Brassicales order, which include vegetables such as cabbages and the model plant Arabidopsis thaliana. Glucoraphanin is the major glucosinolate in broccoli and associated with the health-promoting effects of broccoli consumption. Toward our goal of creating a rich source of glucoraphanin for dietary supplements, we have previously reported the feasibility of engineering glucoraphanin in Nicotiana benthamiana through transient expression of glucoraphanin biosynthetic genes from A. thaliana (Mikkelsen et al., 2010). As side-products, we obtained fivefold to eightfold higher levels of chain-elongated leucine-derived glucosinolates, not found in the native plant. Here, we investigated two different strategies to improve engineering of the methionine chain elongation part of the glucoraphanin pathway in N. benthamiana: (1) coexpression of the large subunit (LSU1) of the heterodimeric isopropylmalate isomerase and (2) coexpression of BAT5 transporter for efficient transfer of intermediates across the chloroplast membrane. We succeeded in raising dihomomethionine (DHM) levels to a maximum of 432 nmol g−1 fresh weight that is equivalent to a ninefold increase compared to the highest production of this intermediate, as previously reported (Mikkelsen et al., 2010). The increased DHM production without increasing leucine-derived side-product levels provides new metabolic engineering strategies for improved glucoraphanin production in a heterologous host. PMID:26909347

  5. Molecular analysis of the cercosporin biosynthetic gene cluster in Cercospora nicotianae.

    PubMed

    Chen, Huiqin; Lee, Miin-Huey; Daub, Margret E; Chung, Kuang-Ren

    2007-05-01

    We describe a core gene cluster, comprised of eight genes (designated CTB1-8), and associated with cercosporin toxin production in Cercospora nicotianae. Sequence analysis identified 10 putative open reading frames (ORFs) flanking the previously characterized CTB1 and CTB3 genes that encode, respectively, the polyketide synthase and a dual methyltransferase/monooxygenase required for cercosporin production. Expression of eight of the genes was co-ordinately induced under cercosporin-producing conditions and was regulated by the Zn(II)Cys(6) transcriptional activator, CTB8. Expression of the genes, affected by nitrogen and carbon sources and pH, was also controlled by another transcription activator, CRG1, previously shown to regulate cercosporin production and resistance. Disruption of the CTB2 gene encoding a methyltransferase or the CTB8 gene yielded mutants that were completely defective in cercosporin production and inhibitory expression of the other CTB cluster genes. Similar 'feedback' transcriptional inhibition was observed when the CTB1, or CTB3 but not CTB4 gene was inactivated. Expression of four ORFs located on the two distal ends of the cluster did not correlate with cercosporin biosynthesis and did not show regulation by CTB8, suggesting that the biosynthetic cluster was limited to CTB1-8. A biosynthetic pathway and a regulatory network leading to cercosporin formation are proposed.

  6. Effects of Iron Excess on Nicotiana plumbaginifolia Plants (Implications to Oxidative Stress).

    PubMed Central

    Kampfenkel, K.; Van Montagu, M.; Inze, D.

    1995-01-01

    Fe excess is believed to generate oxidative stress. To contribute to the understanding of Fe metabolism, Fe excess was induced in Nicotiana plumbaginifolia grown in hydroponic culture upon root cutting. Toxicity symptoms leading to brown spots covering the leaf surface became visible after 6 h. Photosynthesis was greatly affected within 12 h; the photosynthetic rate was decreased by 40%. Inhibition of photosynthesis was accompanied by photoinhibition, increased reduction of photosystem II, and higher thylakoid energization. Fe excess seemed to stimulate photorespiration because catalase activity doubled. To cope with cellular damage, respiration rate increased and cytosolic glucose-6-phosphate dehydrogenase activity more than doubled. Simultaneously, the content of free hexoses was reduced. Indicative of generation of oxidative stress was doubling of ascorbate peroxidase activity within 12 h. Contents of the antioxidants ascorbate and glutathione were reduced by 30%, resulting in equivalent increases of dehydroascorbate and oxidized glutathione. Taken together, moderate changes in leaf Fe content have a dramatic effect on plant metabolism. This indicates that cellular Fe concentrations must be finely regulated to avoid cellular damage most probably because of oxidative stress induced by Fe. PMID:12228397

  7. Localization of Barley yellow dwarf virus Movement Protein Modulating Programmed Cell Death in Nicotiana benthamiana.

    PubMed

    Ju, Jiwon; Kim, Kangmin; Lee, Kui-Jae; Lee, Wang Hu; Ju, Ho-Jong

    2017-02-01

    Barley yellow dwarf virus (BYDV) belongs to Luteovirus and is limited only at phloem related tissues. An open reading frame (ORF) 4 of BYDV codes for the movement protein (MP) of BYDV gating plasmodesmata (PD) to facilitate virus movement. Like other Luteoviruses, ORF 4 of BYDV is embedded in the ORF3 but expressed from the different reading frame in leaky scanning manner. Although MP is a very important protein for systemic infection of BYDV, there was a little information. In this study, MP was characterized in terms of subcellular localization and programmed cell death (PCD). Gene of MP or its mutant (ΔMP) was expressed by Agroinfiltration method. MP was clearly localized at the nucleus and the PD, but ΔMP which was deleted distal N-terminus of MP showed no localization to PD exhibited the different target with original MP. In addition to PD localization, MP appeared associated with small granules in cytoplasm whereas ΔMP did not. MP associated with PD and small granules induced PCD, but ΔMP showed no association with PD and small granules did not exhibit PCD. Based on this study, the distal N-terminal region within MP is seemingly responsible for the localization of PD and the induction small granules and PCD induction. These results suggest that subcellular localization of BYDV MP may modulate the PCD in Nicotiana benthamiana.

  8. Localization of Barley yellow dwarf virus Movement Protein Modulating Programmed Cell Death in Nicotiana benthamiana

    PubMed Central

    Ju, Jiwon; Kim, Kangmin; Lee, Kui-Jae; Lee, Wang Hu; Ju, Ho-Jong

    2017-01-01

    Barley yellow dwarf virus (BYDV) belongs to Luteovirus and is limited only at phloem related tissues. An open reading frame (ORF) 4 of BYDV codes for the movement protein (MP) of BYDV gating plasmodesmata (PD) to facilitate virus movement. Like other Luteoviruses, ORF 4 of BYDV is embedded in the ORF3 but expressed from the different reading frame in leaky scanning manner. Although MP is a very important protein for systemic infection of BYDV, there was a little information. In this study, MP was characterized in terms of subcellular localization and programmed cell death (PCD). Gene of MP or its mutant (ΔMP) was expressed by Agroinfiltration method. MP was clearly localized at the nucleus and the PD, but ΔMP which was deleted distal N-terminus of MP showed no localization to PD exhibited the different target with original MP. In addition to PD localization, MP appeared associated with small granules in cytoplasm whereas ΔMP did not. MP associated with PD and small granules induced PCD, but ΔMP showed no association with PD and small granules did not exhibit PCD. Based on this study, the distal N-terminal region within MP is seemingly responsible for the localization of PD and the induction small granules and PCD induction. These results suggest that subcellular localization of BYDV MP may modulate the PCD in Nicotiana benthamiana. PMID:28167888

  9. Silencing Nicotiana attenuata LHY and ZTL alters circadian rhythms in flowers.

    PubMed

    Yon, Felipe; Joo, Youngsung; Cortés Llorca, Lucas; Rothe, Eva; Baldwin, Ian T; Kim, Sang-Gyu

    2016-02-01

    The rhythmic opening/closing and volatile emissions of flowers are known to attract pollinators at specific times. That these rhythms are maintained under constant light or dark conditions suggests a circadian clock involvement. Although a forward and reverse genetic approach has led to the identification of core circadian clock components in Arabidopsis thaliana, the involvement of these clock components in floral rhythms has remained untested, probably because of the weak diurnal rhythms in A. thaliana flowers. Here, we addressed the role of these core clock components in the flowers of the wild tobacco Nicotiana attenuata, whose flowers open at night, emit benzyl acetone (BA) scents and move vertically through a 140° arc. We first measured N. attenuata floral rhythms under constant light conditions. The results suggest that the circadian clock controls flower opening, BA emission and pedicel movement, but not flower closing. We generated transgenic N. attenuata lines silenced in the homologous genes of Arabidopsis LATE ELONGATED HYPOCOTYL (LHY) and ZEITLUPE (ZTL), which are known to be core clock components. Silencing NaLHY and NaZTL strongly altered floral rhythms in different ways, indicating that conserved clock components in N. attenuata coordinate these floral rhythms.

  10. Role of brassinosteroid signaling in modulating Tobacco mosaic virus resistance in Nicotiana benthamiana

    PubMed Central

    Deng, Xing-Guang; Zhu, Tong; Peng, Xing-Ji; Xi, De-Hui; Guo, Hongqing; Yin, Yanhai; Zhang, Da-Wei; Lin, Hong-Hui

    2016-01-01

    Plant steroid hormones, brassinosteroids (BRs), play essential roles in plant growth, development and stress responses. However, mechanisms by which BRs interfere with plant resistance to virus remain largely unclear. In this study, we used pharmacological and genetic approaches in combination with infection experiments to investigate the role of BRs in plant defense against Tobacco Mosaic Virus (TMV) in Nicotiana benthamiana. Exogenous applied BRs enhanced plant resistance to virus infection, while application of Bikinin (inhibitor of glycogen synthase kinase-3), which activated BR signaling, increased virus susceptibility. Silencing of NbBRI1 and NbBSK1 blocked BR-induced TMV resistance, and silencing of NbBES1/BZR1 blocked Bikinin-reduced TMV resistance. Silencing of NbMEK2, NbSIPK and NbRBOHB all compromised BR-induced virus resistance and defense-associated genes expression. Furthermore, we found MEK2-SIPK cascade activated while BES1/BZR1 inhibited RBOHB-dependent ROS production, defense gene expression and virus resistance induced by BRs. Thus, our results revealed BR signaling had two opposite effects on viral defense response. On the one hand, BRs enhanced virus resistance through MEK2-SIPK cascade and RBOHB-dependent ROS burst. On the other hand, BES1/BZR1 inhibited RBOHB-dependent ROS production and acted as an important mediator of the trade-off between growth and immunity in BR signaling. PMID:26838475

  11. Nicotiana benthamiana: Its History and Future as a Model for Plant-Pathogen Interactions.

    PubMed

    Goodin, Michael M; Zaitlin, David; Naidu, Rayapati A; Lommel, Steven A

    2015-01-01

    Nicotiana benthamiana is the most widely used experimental host in plant virology, due mainly to the large number of diverse plant viruses that can successfully infect it. Addi- tionally, N. benthamiana is susceptible to a wide variety of other plant-pathogenic agents (such as bacteria, oomycetes, fungi, and so on), making this species a cornerstone of host-pathogen research, particularly in the context of innate immunity and defense signaling. Moreover, because it can be genetically transformed and regenerated with good efficiency and is amenable to facile methods for virus- induced gene silencing or transient protein expression, N. benthamiana is rapidly gaining popularity in plant biology, particularly in studies requiring protein localization, inter- action, or plant-based systems for protein expression and purification. Paradoxically, despite being an indispensable research model, little is known about the origins, genetic variation, or ecology of the N. benthamiana accessions cur- rently used by the research community. In addition to ad- dressing these latter topics, the purpose of this review is to provide information regarding sources for tools and reagents that can be used to support research in N. benthamiana. Finally, we propose that N. benthamiana is well situated to become a premier plant cell biology model, particularly for the virology community, who as a group were the first to recognize the potential of this unique Australian native.

  12. Molecular Characterization of the Cercosporin Biosynthetic Pathway in the Fungal Plant Pathogen Cercospora nicotianae

    PubMed Central

    Newman, Adam G.; Townsend, Craig A.

    2016-01-01

    Perylenequinones are a class of photoactivated polyketide mycotoxins produced by fungal plant pathogens that notably produce reactive oxygen species with visible light. The best-studied perylenequinone is cercosporin—a product of the Cercospora species. While the cercosporin biosynthetic gene cluster has been described in the tobacco pathogen Cercospora nicotianae, little is known of the metabolite’s biosynthesis. Furthermore, in vitro investigations of the polyketide synthase central to cercosporin biosynthesis identified the naphthopyrone nor-toralactone as its direct product—an observation in conflict with published biosynthetic proposals. Here, we present an alternative biosynthetic pathway to cercosporin based on metabolites characterized from a series of biosynthetic gene knockouts. We show that nor-toralactone is the key polyketide intermediate and the substrate for the unusual didomain protein CTB3. We demonstrate the unique oxidative cleavage activity of the CTB3 monooxygenase domain in vitro. These data advance our understanding of perylenequinone biosynthesis and expand the biochemical repertoire of flavin-dependent monooxygenases. PMID:26938470

  13. Silencing Nicotiana attenuata LHY and ZTL alters circadian rhythms in flowers

    PubMed Central

    Yon, Felipe; Joo, Youngsung; Cortés Llorca, Lucas; Rothe, Eva; Baldwin, Ian T.; Kim, Sang-Gyu

    2016-01-01

    Summary The rhythmic opening/closing and volatile emissions of flowers is known to attract pollinators at specific times. That these rhythms are maintained under constant light or dark conditions suggests a circadian clock involvement. Although a forward and reverse genetic approach led to the identification of core circadian clock components in Arabidopsis thaliana, involvement of these clock components for floral rhythms remained untested likely due to weak diurnal rhythms in A. thaliana flowers.Here we addressed the role of these core clock components in the flowers of the wild tobacco Nicotiana attenuata, whose flowers open at night, emit benzyl acetone (BA) scents, and move vertically through a 140° arc.We first measured N. attenuata floral rhythms under constant light conditions. The results suggest that the circadian clock controls flower opening, BA emission, and pedicel movement, but not flower closing.We generated transgenic N. attenuata lines silenced in the homologous genes of Arabidopsis LATE ELONGATED HYPOCOTYL (LHY) and ZEITLUPE (ZTL), which are known as a core clock component. Silencing NaLHY and NaZTL strongly altered floral rhythms in different ways, indicating that conserved clock components in N. attenuata coordinate these floral rhythms. PMID:26439540

  14. Fiber Bragg Grating Temperature Sensor for Defence and Industrial Applications

    NASA Astrophysics Data System (ADS)

    Gebru, Haftay Abadi; Padhy, B. B.

    2011-10-01

    This paper presents the design and development of fiber Bragg grating (FBG) temperature sensor suitable for naval applications like temperature monitoring of onboard ships. The Bragg gratings used here have a reflection Bragg wavelength of 1550 nm and are inscribed by phase mask technique using ultraviolet (UV) laser beam at 255.3 nm. The high-resolution temperature sensor has been designed and developed based on the principle of converting the strain to temperature. This is achieved by using bimetallic configuration. Here lead and tungsten metals are used. The expansion of lead is concentrated on the Bragg grating, thus imparting strain on it. The wavelength shift with change of temperature is recorded with optical spectrum analyzer. The minimum temperature that could be measured accurately by the sensor with repeatability is of the order of 10-2. We have achieved thermal sensitivity of 46 pm/°C and 72 pm/°C for sensor lengths (length of the metallic strips) of 60 mm and 100 mm respectively. The thermal sensitivity achieved is approximately 3.5 times and 5.5 times that of bare FBG with thermal sensitivity of 13 pm/°C for the respective sensor lengths. This type of sensor can play vital role in defence and industrial applications like monitoring fresh water/lubricating oil temperatures of machinery in onboard ships, temperature monitoring of airframe of the aircraft, aircraft engine control system sensors, temperature measurement of hot gases from propellant combustion to protect the rocket motor casing, monitoring and control of temperature of copper bars of the power generators etc.

  15. Constitutive immune defences correlate with life-history variables in tropical birds.

    PubMed

    Lee, K A; Wikelski, M; Robinson, W D; Robinson, T R; Klasing, K C

    2008-03-01

    1. It has been suggested that immune defences are shaped by life history and ecology, but few general patterns have been described across species. We hypothesized that 'fast' life-history traits (e.g. short development times, large clutch sizes) would be associated with developmentally inexpensive immune defences, minimizing the resource demands of young animals' immune systems during periods of rapid growth. Conversely, 'slow' life histories should be associated with well developed antibody-mediated defences, which are developmentally costly. 2. We therefore predicted that 'fast-living' species would exhibit higher levels of complement proteins, a component of non-specific innate defence, but lower levels of constitutive ('natural') antibodies. Additionally, we predicted that constitutive immune defences in general would be higher in species with ecological characteristics that might increase exposure to pathogens, such as open nests, omnivorous diets, gregariousness, and closed forested habitat. 3. Across 70 Neotropical bird species, we found a strongly positive relationship between incubation period and natural antibody levels in adult birds, suggesting that longer developmental times might allow the production of a more diverse and/or more reactive adaptive immune system. Complement activity was positively, although weakly, correlated with clutch size, providing some support for the hypothesis that faster-living species rely more on innate defences, such as complement. Unexpectedly, solitary species had higher natural antibody titres than species that frequently join flocks. 4. Our results suggest that, despite probably widespread differences in the intensity and diversity of pathogen exposure, species-level variation in constitutive immune defences is understandable within the context of life-history theory.

  16. Predator-induced defences in Daphnia longicephala: location of kairomone receptors and timeline of sensitive phases to trait formation.

    PubMed

    Weiss, Linda C; Leimann, Julian; Tollrian, Ralph

    2015-09-01

    The freshwater crustacean Daphnia adapts to changing predation risks by forming inducible defences. These are only formed when they are advantageous, saving associated costs when the defence is superfluous. However, in order to be effective, the time lag between the onset of predation and the defence formation has to be short. Daphnia longicephala develop huge protective crests upon exposure to chemical cues (kairomones) from its predator the heteropteran backswimmer Notonecta glauca. To analyse time lags, we determined kairomone-sensitive stages and the developmental time frames of inducible defences. Moreover, we looked at additive effects that could result from the summation of prolonged kairomone exposure. Kairomones are perceived by chemoreceptors and integrated by the nervous system, which alters the developmental program leading to defence formation. The underlying neuronal and developmental pathways are not thoroughly described and surprisingly, the location of the kairomone receptors is undetermined. We show that D. longicephala start to sense predator cues at the onset of the second juvenile instar, defences develop with a time lag of one instar and prolonged kairomone exposure does not impact the magnitude of the defence. By establishing a method to reversibly impair chemosensors, we show the first antennae as the location of kairomone-detecting chemoreceptors. This study provides fundamental information on kairomone perception, kairomone-sensitive stages, developmental time frames and lag times of inducible defences in D. longicephala that will greatly contribute to the further understanding of the neuronal and developmental mechanisms of predator-induced defences in Daphnia.

  17. Leaf Colour as a Signal of Chemical Defence to Insect Herbivores in Wild Cabbage (Brassica oleracea)

    PubMed Central

    Wilkins, Lucas; Osorio, Daniel; Hartley, Susan E.

    2015-01-01

    Leaf colour has been proposed to signal levels of host defence to insect herbivores, but we lack data on herbivory, leaf colour and levels of defence for wild host populations necessary to test this hypothesis. Such a test requires measurements of leaf spectra as they would be sensed by herbivore visual systems, as well as simultaneous measurements of chemical defences and herbivore responses to leaf colour in natural host-herbivore populations. In a large-scale field survey of wild cabbage (Brassica oleracea) populations, we show that variation in leaf colour and brightness, measured according to herbivore spectral sensitivities, predicts both levels of chemical defences (glucosinolates) and abundance of specialist lepidopteran (Pieris rapae) and hemipteran (Brevicoryne brassicae) herbivores. In subsequent experiments, P. rapae larvae achieved faster growth and greater pupal mass when feeding on plants with bluer leaves, which contained lower levels of aliphatic glucosinolates. Glucosinolate-mediated effects on larval performance may thus contribute to the association between P. rapae herbivory and leaf colour observed in the field. However, preference tests found no evidence that adult butterflies selected host plants based on leaf coloration. In the field, B. brassicae abundance varied with leaf brightness but greenhouse experiments were unable to identify any effects of brightness on aphid preference or performance. Our findings suggest that although leaf colour reflects both levels of host defences and herbivore abundance in the field, the ability of herbivores to respond to colour signals may be limited, even in species where performance is correlated with leaf colour. PMID:26353086

  18. Leaf Colour as a Signal of Chemical Defence to Insect Herbivores in Wild Cabbage (Brassica oleracea).

    PubMed

    Green, Jonathan P; Foster, Rosie; Wilkins, Lucas; Osorio, Daniel; Hartley, Susan E

    2015-01-01

    Leaf colour has been proposed to signal levels of host defence to insect herbivores, but we lack data on herbivory, leaf colour and levels of defence for wild host populations necessary to test this hypothesis. Such a test requires measurements of leaf spectra as they would be sensed by herbivore visual systems, as well as simultaneous measurements of chemical defences and herbivore responses to leaf colour in natural host-herbivore populations. In a large-scale field survey of wild cabbage (Brassica oleracea) populations, we show that variation in leaf colour and brightness, measured according to herbivore spectral sensitivities, predicts both levels of chemical defences (glucosinolates) and abundance of specialist lepidopteran (Pieris rapae) and hemipteran (Brevicoryne brassicae) herbivores. In subsequent experiments, P. rapae larvae achieved faster growth and greater pupal mass when feeding on plants with bluer leaves, which contained lower levels of aliphatic glucosinolates. Glucosinolate-mediated effects on larval performance may thus contribute to the association between P. rapae herbivory and leaf colour observed in the field. However, preference tests found no evidence that adult butterflies selected host plants based on leaf coloration. In the field, B. brassicae abundance varied with leaf brightness but greenhouse experiments were unable to identify any effects of brightness on aphid preference or performance. Our findings suggest that although leaf colour reflects both levels of host defences and herbivore abundance in the field, the ability of herbivores to respond to colour signals may be limited, even in species where performance is correlated with leaf colour.

  19. "New Sport" in the street: self-defence, security and space in belle epoque Paris.

    PubMed

    Freundschuh, Aaron

    2006-01-01

    Near the turn of the twentieth century, traditional self-defence methods (for example, jiu-jitsu) were revamped into a more accessible and practical set of techniques and tactics for everyday use in urban public space. Framed as a "new sport" with broad public utility, early urban self-defence developed against the backdrop of heightening fears of violent crime and a burgeoning politics of security, as well as tensions provoked by the increasingly common appearance of unchaperoned, middle-class women in public. Self-defence masters pitched their innovations in an inclusive rhetoric, always with separate lessons for men and women and their respective spaces of risk. This article places modern self-defence practices in tension with historical transformations in the urban landscape, arguing that urban self-defence posited a certain subjective relation to the city that tapped simultaneously into the desire for empowerment, fantasies of criminal danger and a law-and-order tone that shaded into urban vigilantism.

  20. Future directions in the ontogeny of plant defence: understanding the evolutionary causes and consequences.

    PubMed

    Barton, Kasey E; Boege, Karina

    2017-04-01

    Plant defence often varies by orders of magnitude as plants develop from the seedling to juvenile to mature and senescent stages. Ontogenetic trajectories can involve switches among defence traits, leading to complex shifting phenotypes across plant lifetimes. While considerable research has characterised ontogenetic trajectories for now hundreds of plant species, we still lack a clear understanding of the molecular, ecological and evolutionary factors driving these patterns. In this study, we identify several non-mutually exclusive factors that may have led to the evolution of ontogenetic trajectories in plant defence, including developmental constraints, resource allocation costs, multi-functionality of defence traits, and herbivore selection pressure. Evidence from recent physiological studies is highlighted to shed light on the underlying molecular mechanisms involved in the regulation and activation of these developmental changes. Overall, our goal is to promote new research avenues that would provide evidence for the factors that have promoted the evolution of this complex lifetime phenotype. Future research focusing on the questions and approaches identified here will advance the field and shed light on why defence traits shift so dramatically across plant ontogeny, a widespread but poorly understood ecological pattern.

  1. Crowd-out of defence and health spending: is Israel different from other industrialised nations?

    PubMed Central

    2013-01-01

    Does high defence spending limit the growth of public health investment? Using comparative data from 31 OECD countries between 1980 and 2010, we find little evidence that defence crowds out public health spending. Whether measured in terms of long-term levels or short-term changes, per capita defence and health spending positively and significantly correlate. To investigate the possibility that countries with high security needs such as Israel exhibit differing patterns, we also compare crowd-out among countries experiencing violent conflicts as well as current high military-spending countries. We observed a greater positive correlation between changes in health and defence spending among conflict-countries (r = 0.65, p < 0.01) than in non-conflict countries (r = 0.12, p = 0.01). However, similar to other high-military spending countries, Israel’s politicians reduced defence spending while increasing health expenditure during its recent recession. These analyses reveal that while Israel’s politicians have chronically underinvested in public health, there are modest steps being taken to rectify the country’s unique and avoidable crowding out of public health from its high military spending. PMID:23607605

  2. Natural selection on quantitative immune defence traits: a comparison between theory and data.

    PubMed

    Seppälä, O

    2015-01-01

    Parasites present a threat for free-living species and affect several ecological and evolutionary processes. Immune defence is the main physiological barrier against infections, and understanding its evolution is central for predicting disease dynamics. I review theoretical predictions and empirical data on natural selection on quantitative immune defence traits in the wild. Evolutionary theory predicts immune traits to be under stabilizing selection owing to trade-offs between immune function and life-history traits. Empirical data, however, support mainly positive directional selection, but also show variation in the form of selection among study systems, immune traits and fitness components. I argue that the differences between theory and empirical data may at least partly arise from methodological difficulties in testing stabilizing selection as well as measuring fitness. I also argue that the commonness of positive directional selection and the variation in selection may be caused by several biological factors. First, selection on immune function may show spatial and temporal variation as epidemics are often local/seasonal. Second, factors affecting the range of phenotypic variation in immune traits could alter potential for selection. Third, different parasites may impose different selective pressures depending on their characteristics. Fourth, condition dependence of immune defence can obscure trade-offs related to it, thus possibly modifying observed selection gradients. Fifth, nonimmunological defences could affect the form of selection by reducing the benefits of strong immune function. To comprehensively understand the evolution of immune defence, the role of above factors should be considered in future studies.

  3. Rapid evolution of antioxidant defence in a natural population of Daphnia magna.

    PubMed

    Oexle, S; Jansen, M; Pauwels, K; Sommaruga, R; De Meester, L; Stoks, R

    2016-07-01

    Natural populations can cope with rapid changes in stressors by relying on sets of physiological defence mechanisms. Little is known onto what extent these physiological responses reflect plasticity and/or genetic adaptation, evolve in the same direction and result in an increased defence ability. Using resurrection ecology, we studied how a natural Daphnia magna population adjusted its antioxidant defence to ultraviolet radiation (UVR) during a period with increasing incident UVR reaching the water surface. We demonstrate a rapid evolution of the induction patterns of key antioxidant enzymes under UVR exposure in the laboratory. Notably, evolutionary changes strongly differed among enzymes and mainly involved the evolution of UV-induced plasticity. Whereas D. magna evolved a strong plastic up-regulation of glutathione peroxidase under UVR, it evolved a lower plastic up-regulation of glutathione S-transferase and superoxide dismutase and a plastic down-regulation of catalase. The differentially evolved antioxidant strategies were collectively equally effective in dealing with oxidative stress because they resulted in the same high levels of oxidative damage (to lipids, proteins and DNA) and lowered fitness (intrinsic growth rate) under UVR exposure. The lack of better protection against UVR may suggest that the UVR exposure did not increase between both periods. Predator-induced evolution to migrate to lower depths that occurred during the same period may have contributed to the evolved defence strategy. Our results highlight the need for a multiple trait approach when focusing on the evolution of defence mechanisms.

  4. Plant defence suppression is mediated by a fungal sirtuin during rice infection by Magnaporthe oryzae.

    PubMed

    Fernandez, Jessie; Marroquin-Guzman, Margarita; Nandakumar, Renu; Shijo, Sara; Cornwell, Kathryn M; Li, Gang; Wilson, Richard A

    2014-10-01

    Crop destruction by the hemibiotrophic rice pathogen Magnaporthe oryzae requires plant defence suppression to facilitate extensive biotrophic growth in host cells before the onset of necrosis. How this is achieved at the genetic level is not well understood. Here, we report that a M. oryzae sirtuin, MoSir2, plays an essential role in rice defence suppression and colonization by controlling superoxide dismutase (SOD) gene expression. Loss of MoSir2 function in Δsir2 strains did not affect appressorial function, but biotrophic growth in rice cells was attenuated. Compared to wild type, Δsir2 strains failed to neutralize plant-derived reactive oxygen species (ROS) and elicited robust defence responses in rice epidermal cells that included elevated pathogenesis-related gene expression and granular depositions. Deletion of a SOD-encoding gene under MoSir2 control generated Δsod1 deletion strains that mimicked Δsir2 for impaired rice defence suppression, confirming SOD activity as a downstream output of MoSir2. In addition, comparative protein acetylation studies and forward genetic analyses identified a JmjC domain-containing protein as a likely target of MoSir2, and a Δsir2 Δjmjc double mutant was restored for MoSOD1 expression and defence suppression in rice epidermal cells. Together, this work reveals MoSir2 and MoJmjC as novel regulators of early rice cell infection.

  5. Growth-defence balance in grass biomass production: the role of jasmonates.

    PubMed

    Shyu, Christine; Brutnell, Thomas P

    2015-07-01

    Growth-defence balance is the selective partitioning of resources between biomass accumulation and defence responses. Although it is generally postulated that reallocation of limited carbon pools drives the antagonism between growth and defence, little is known about the mechanisms underlying this regulation. Jasmonates (JAs) are a group of oxylipins that are required for a broad range of responses from defence against insects to reproductive growth. Application of JAs to seedlings also leads to inhibited growth and repression of photosynthesis, suggesting a role for JAs in regulating growth-defence balance. The majority of JA research uses dicot models such as Arabidopsis and tomato, while understanding of JA biology in monocot grasses, which comprise most bioenergy feedstocks, food for human consumption, and animal feed, is limited. Interestingly, JA mutants of grasses exhibit unique phenotypes compared with well-studied dicot models. Gene expression analyses in bioenergy grasses also suggest roles for JA in rhizome development, which has not been demonstrated in Arabidopsis. In this review we summarize current knowledge of JA biology in panicoid grasses-the group that consists of the world's emerging bioenergy grasses such as switchgrass, sugarcane, Miscanthus, and sorghum. We discuss outstanding questions regarding the role of JAs in panicoid grasses, and highlight the importance of utilizing emerging grass models for molecular studies to provide a basis for engineering bioenergy grasses that can maximize biomass accumulation while efficiently defending against stress.

  6. The nexus between growth and defence signalling: auxin and cytokinin modulate plant immune response pathways.

    PubMed

    Naseem, Muhammad; Kaltdorf, Martin; Dandekar, Thomas

    2015-08-01

    Plants deploy a finely tuned balance between growth and defence responses for better fitness. Crosstalk between defence signalling hormones such as salicylic acid (SA) and jasmonates (JAs) as well as growth regulators plays a significant role in mediating the trade-off between growth and defence in plants. Here, we specifically discuss how the mutual antagonism between the signalling of auxin and SA impacts on plant growth and defence. Furthermore, the synergism between auxin and JA benefits a class of plant pathogens. JA signalling also poses growth cuts through auxin. We discuss how the effect of cytokinins (CKs) is multifaceted and is effective against a broad range of pathogens in mediating immunity. The synergism between CKs and SA promotes defence against biotrophs. Reciprocally, SA inhibits CK-mediated growth responses. Recent reports show that CKs promote JA responses; however, in a feedback loop, JA suppresses CK responses. We also highlight crosstalk between auxin and CKs and discuss their antagonistic effects on plant immunity. Efforts to minimize the negative effects of auxin on immunity and a reduction in SA- and JA-mediated growth losses should lead to better sustainable plant protection strategies.

  7. Light acclimation, retrograde signalling, cell death and immune defences in plants.

    PubMed

    Karpiński, Stanisław; Szechyńska-Hebda, Magdalena; Wituszyńska, Weronika; Burdiak, Paweł

    2013-04-01

    This review confronts the classical view of plant immune defence and light acclimation with recently published data. Earlier findings have linked plant immune defences to nucleotide-binding site leucine-rich repeat (NBS-LRR)-dependent recognition of pathogen effectors and to the role of plasma membrane-localized NADPH-dependent oxidoreductase (AtRbohD), reactive oxygen species (ROS) and salicylic acid (SA). However, recent results suggest that plant immune defence also depends on the absorption of excessive light energy and photorespiration. Rapid changes in light intensity and quality often cause the absorption of energy, which is in excess of that required for photosynthesis. Such excessive light energy is considered to be a factor triggering photoinhibition and disturbance in ROS/hormonal homeostasis, which leads to cell death in foliar tissues. We highlight here the tight crosstalk between ROS- and SA-dependent pathways leading to light acclimation, and defence responses leading to pathogen resistance. We also show that LESION SIMULATING DISEASE 1 (LSD1) regulates and integrates these processes. Moreover, we discuss the role of plastid-nucleus signal transduction, photorespiration, photoelectrochemical signalling and 'light memory' in the regulation of acclimation and immune defence responses. All of these results suggest that plants have evolved a genetic system that simultaneously regulates systemic acquired resistance (SAR), cell death and systemic acquired acclimation (SAA).

  8. Targeted predation of extrafloral nectaries by insects despite localized chemical defences.

    PubMed

    Gish, Moshe; Mescher, Mark C; De Moraes, Consuelo M

    2015-10-07

    Extrafloral (EF) nectaries recruit carnivorous arthropods that protect plants from herbivory, but they can also be exploited by nectar thieves. We studied the opportunistic, targeted predation (and destruction) of EF nectaries by insects, and the localized chemical defences that plants presumably use to minimize this effect. In field and laboratory experiments, we identified insects that were possibly responsible for EF nectary predation in Vicia faba (fava bean) and determined the extent and accuracy of the feeding damage done to the EF nectaries by these insects. We also performed biochemical analyses of plant tissue samples in order to detect microscale distribution patterns of chemical defences in the area of the EF nectary. We observed selective, targeted feeding on EF nectaries by several insect species, including some that are otherwise not primarily herbivorous. Biochemical analyses revealed high concentrations of l-3,4-dihydroxyphenylalanine, a non-protein amino acid that is toxic to insects, near and within the EF nectaries. These results suggest that plants allocate defences to the protection of EF nectaries from predation, consistent with expectations of optimal defence theory, and that this may not be entirely effective, as insects limit their exposure to these defences by consuming only the secreting tissue of the nectary.

  9. Targeted predation of extrafloral nectaries by insects despite localized chemical defences

    PubMed Central

    Gish, Moshe; Mescher, Mark C.; De Moraes, Consuelo M.

    2015-01-01

    Extrafloral (EF) nectaries recruit carnivorous arthropods that protect plants from herbivory, but they can also be exploited by nectar thieves. We studied the opportunistic, targeted predation (and destruction) of EF nectaries by insects, and the localized chemical defences that plants presumably use to minimize this effect. In field and laboratory experiments, we identified insects that were possibly responsible for EF nectary predation in Vicia faba (fava bean) and determined the extent and accuracy of the feeding damage done to the EF nectaries by these insects. We also performed biochemical analyses of plant tissue samples in order to detect microscale distribution patterns of chemical defences in the area of the EF nectary. We observed selective, targeted feeding on EF nectaries by several insect species, including some that are otherwise not primarily herbivorous. Biochemical analyses revealed high concentrations of l-3,4-dihydroxyphenylalanine, a non-protein amino acid that is toxic to insects, near and within the EF nectaries. These results suggest that plants allocate defences to the protection of EF nectaries from predation, consistent with expectations of optimal defence theory, and that this may not be entirely effective, as insects limit their exposure to these defences by consuming only the secreting tissue of the nectary. PMID:26446809

  10. Mating with large males decreases the immune defence of females in Drosophila melanogaster.

    PubMed

    Imroze, K; Prasad, N G

    2011-12-01

    Mating has been widely reported to be a costly event for females. Studies indicate that female cost of mating in terms of fecundity and survivorship can be affected by their mates, leading to antagonistic coevolution between the sexes. However, as of now, there is no evidence that the female cost of mating in terms of immune defence is affected by their mates. We assess the effect of different sized males on antibacterial immune defence and reproductive fitness of their mates. We used a large outbred population of Drososphila melanogaster as the host and Serratia marcescens as the pathogen. We generated three different male phenotypes: small, medium and large, by manipulating larval densities. Compared to females mating with small males, those mating with large males had higher bacterial loads and lower fecundity. There was no significant effect of male phenotype on the fraction of females mated or copulation duration (an indicator of ejaculate investment). Thus, our study is the first clear demonstration that male phenotype can affect the cost of mating to females in terms of their antibacterial immune defence. Mating with large males imposes an additional cost of mating to females in terms of reduced immune defence. The observed results are very likely due to qualitative/quantitative differences in the ejaculates of the three different types of males. If the phenotypic variation that we observed in males in our study is mirrored by genetic variation, then, it can potentially lead to antagonistic coevolution of the sexes over immune defence.

  11. Ethylene and the Regulation of Senescence Processes in Transgenic Nicotiana sylvestris Plants

    PubMed Central

    Yang, Thomas F.; Gonzalez-Carranza, Zinnia H.; Maunders, Martin J.; Roberts, Jeremy A.

    2008-01-01

    Background and Aims Exposure of plants to ethylene can influence a spectrum of developmental processes including organ senescence and abscission. The aim of this study was to examine the role of the gaseous regulator in Nicotiana sylvestris plants exhibiting a silenced or constitutive ethylene response. Methods Transgenic N. sylvestris plants were generated that either ectopically expressed the Arabidopsis mutant ethylene receptor ETR1-1 or the tomato EIN3-like (LeEIL1) gene. Highly expressing homozygous lines were selected and the time-course of development, from germination to organ senescence, was studied. Key Results Fifty percent of the homozygous Pro35S:ETR1-1 lines examined showed a high susceptibility to collapse prior to flowering, with plant death occurring within a few days of leaf wilting. The time-course of leaf senescence in the remaining Pro35S:ETR1-1 lines was visibly arrested compared to wild type (negative segregant) plants and this observation was reaffirmed by chlorophyll and protein analysis. Petal necrosis was also delayed in Pro35S:ETR1-1 lines and corolla abscission did not take place. When senescence of Pro35S:ETR1-1 plants did take place this was accompanied by leaf bleaching, but tissues remained fully turgid and showed no signs of collapse. A single Pro35S:LeEIL1 line was found to exhibit consistently accelerated leaf and flower senescence and precocious flower bud shedding. Conclusions These observations support a role for ethylene in regulating a spectrum of developmental events associated with organ senescence and tissue necrosis. Furthermore, the transgenic lines generated during this study may provide a valuable resource for exploring how senescence processes are regulated in plants. PMID:17901061

  12. Silencing of a germin-like gene in Nicotiana attenuata improves performance of native herbivores.

    PubMed

    Lou, Yonggen; Baldwin, Ian T

    2006-03-01

    Germins and germin-like proteins (GLPs) are known to function in pathogen resistance, but their involvement in defense against insect herbivores is poorly understood. In the native tobacco Nicotiana attenuata, attack from the specialist herbivore Manduca sexta or elicitation by adding larval oral secretions (OS) to wounds up-regulates transcripts of a GLP. To understand the function of this gene, which occurs as a single copy, we cloned the full-length NaGLP and silenced its expression in N. attenuata by expressing a 250-bp fragment in an antisense orientation with an Agrobacterium-based transformation system and by virus-induced gene silencing (VIGS). Homozygous lines harboring a single insert and VIGS plants had significantly reduced constitutive (measured in roots) and elicited NaGLP transcript levels (in leaves). Silencing NaGLP improved M. sexta larval performance and Tupiocoris notatus preference, two native herbivores of N. attenuata. Silencing NaGLP also attenuated the OS-induced hydrogen peroxide (H(2)O(2)), diterpene glycosides, and trypsin proteinase inhibitor responses, which may explain the observed susceptibility of antisense or VIGS plants to herbivore attack and increased nicotine contents, but did not influence the OS-elicited jasmonate and salicylate bursts, or the release of the volatile organic compounds (limonene, cis-alpha-bergamotene, and germacrene-A) that function as an indirect defense. This suggests that NaGLP is involved in H(2)O(2) production and might also be related to ethylene production and/or perception, which in turn influences the defense responses of N. attenuata via H(2)O(2) and ethylene-signaling pathways.

  13. HSPRO controls early Nicotiana attenuata seedling growth during interaction with the fungus Piriformospora indica.

    PubMed

    Schuck, Stefan; Camehl, Iris; Gilardoni, Paola A; Oelmueller, Ralf; Baldwin, Ian T; Bonaventure, Gustavo

    2012-10-01

    In a previous study aimed at identifying regulators of Nicotiana attenuata responses against chewing insects, a 26-nucleotide tag matching the HSPRO (ORTHOLOG OF SUGAR BEET Hs1(pro)(-)(1)) gene was found to be strongly induced after simulated herbivory (Gilardoni et al., 2010). Here we characterized the function of HSPRO during biotic interactions in transgenic N. attenuata plants silenced in its expression (ir-hspro). In wild-type plants, HSPRO expression was not only induced during simulated herbivory but also when leaves were inoculated with Pseudomonas syringae pv tomato DC3000 and roots with the growth-promoting fungus Piriformospora indica. Reduced HSPRO expression did not affect the regulation of direct defenses against Manduca sexta herbivory or P. syringae pv tomato DC3000 infection rates. However, reduced HSPRO expression positively influenced early seedling growth during interaction with P. indica; fungus-colonized ir-hspro seedlings increased their fresh biomass by 30% compared with the wild type. Grafting experiments demonstrated that reduced HSPRO expression in roots was sufficient to induce differential growth promotion in both roots and shoots. This effect was accompanied by changes in the expression of 417 genes in colonized roots, most of which were metabolic genes. The lack of major differences in the metabolic profiles of ir-hspro and wild-type colonized roots (as analyzed by liquid chromatography time-of-flight mass spectrometry) suggested that accelerated metabolic rates were involved. We conclude that HSPRO participates in a whole-plant change in growth physiology when seedlings interact with P. indica.

  14. Heterologous expression and characterization of choline oxidase from the soil bacterium Arthrobacter nicotianae.

    PubMed

    Ribitsch, D; Karl, W; Wehrschütz-Sigl, E; Tutz, S; Remler, P; Weber, H J; Gruber, K; Stehr, R; Bessler, C; Hoven, N; Sauter, K; Maurer, K H; Schwab, H

    2009-01-01

    In the course of a microbial screening of soil samples for new oxidases, different enrichment strategies were carried out. With choline as the only carbon source, a microorganism was isolated and identified as Arthrobacter nicotianae. From this strain, a gene coding for a choline oxidase was isolated from chromosomal DNA. This gene named codA was cloned in Escherichia coli BL21-Gold and the protein (An_CodA) heterologously overexpressed as a soluble intracellular protein of 59.1 kDa. Basic biochemical characterization of purified protein revealed a pH optimum of 7.4 and activity over a broad temperature range (15-70 degrees C). Specific activities were determined toward choline chloride (4.70 +/- 0.12 U/mg) and the synthetic analogs bis(2-hydroxyethyl)-dimethylammonium chloride (0.05 +/- 0.45 x 10(-2) U/mg) and tris-(2-hydroxyethyl)-methylammonium methylsulfate (0.01 +/- 0.12 x 10(-2) U/mg). With increasing number of oxidizable groups, a significant decrease in activity was noted. Determination of kinetic parameters in atmorspheric oxygen resulted in K (M) = 1.51 +/- 0.09 mM and V (max) = 42.73 +/- 0.42 mU/min for choline chloride and K (M) = 4.77 +/- 0.76 mM and V (max) = 48.40 +/- 2.88 mU/min for the reaction intermediate betaine aldehyde respectively. Nuclear magnetic resonance spectroscopic analysis of the products formed during the enzyme reaction with choline chloride showed that in vitro the intermediate betaine aldehyde exists also free in solution.

  15. Production of an active anti-CD20-hIL-2 immunocytokine in Nicotiana benthamiana.

    PubMed

    Marusic, Carla; Novelli, Flavia; Salzano, Anna M; Scaloni, Andrea; Benvenuto, Eugenio; Pioli, Claudio; Donini, Marcello

    2016-01-01

    Anti-CD20 murine or chimeric antibodies (Abs) have been used to treat non-Hodgkin lymphomas (NHLs) and other diseases characterized by overactive or dysfunctional B cells. Anti-CD20 Abs demonstrated to be effective in inducing regression of B-cell lymphomas, although in many cases patients relapse following treatment. A promising approach to improve the outcome of mAb therapy is the use of anti-CD20 antibodies to deliver cytokines to the tumour microenvironment. In particular, IL-2-based immunocytokines have shown enhanced antitumour activity in several preclinical studies. Here, we report on the engineering of an anti-CD20-human interleukin-2 (hIL-2) immunocytokine (2B8-Fc-hIL2) based on the C2B8 mAb (Rituximab) and the resulting ectopic expression in Nicotiana benthamiana. The scFv-Fc-engineered immunocytokine is fully assembled in plants with minor degradation products as assessed by SDS-PAGE and gel filtration. Purification yields using protein-A affinity chromatography were in the range of 15-20 mg/kg of fresh leaf weight (FW). Glycopeptide analysis confirmed the presence of a highly homogeneous plant-type glycosylation. 2B8-Fc-hIL2 and the cognate 2B8-Fc antibody, devoid of hIL-2, were assayed by flow cytometry on Daudi cells revealing a CD20 binding activity comparable to that of Rituximab and were effective in eliciting antibody-dependent cell-mediated cytotoxicity of human PBMC versus Daudi cells, demonstrating their functional integrity. In 2B8-Fc-hIL2, IL-2 accessibility and biological activity were verified by flow cytometry and cell proliferation assay. To our knowledge, this is the first example of a recombinant immunocytokine based on the therapeutic Rituximab antibody scaffold, whose expression in plants may be a valuable tool for NHLs treatment.

  16. Leaf proteome rebalancing in Nicotiana benthamiana for upstream enrichment of a transiently expressed recombinant protein.

    PubMed

    Robert, Stéphanie; Goulet, Marie-Claire; D'Aoust, Marc-André; Sainsbury, Frank; Michaud, Dominique

    2015-10-01

    A key factor influencing the yield of biopharmaceuticals in plants is the ratio of recombinant to host proteins in crude extracts. Postextraction procedures have been devised to enrich recombinant proteins before purification. Here, we assessed the potential of methyl jasmonate (MeJA) as a generic trigger of recombinant protein enrichment in Nicotiana benthamiana leaves before harvesting. Previous studies have reported a significant rebalancing of the leaf proteome via the jasmonate signalling pathway, associated with ribulose 1,5-bisphosphate carboxylase oxygenase (RuBisCO) depletion and the up-regulation of stress-related proteins. As expected, leaf proteome alterations were observed 7 days post-MeJA treatment, associated with lowered RuBisCO pools and the induction of stress-inducible proteins such as protease inhibitors, thionins and chitinases. Leaf infiltration with the Agrobacterium tumefaciens bacterial vector 24 h post-MeJA treatment induced a strong accumulation of pathogenesis-related proteins after 6 days, along with a near-complete reversal of MeJA-mediated stress protein up-regulation. RuBisCO pools were partly restored upon infiltration, but most of the depletion effect observed in noninfiltrated plants was maintained over six more days, to give crude protein samples with 50% less RuBisCO than untreated tissue. These changes were associated with net levels reaching 425 μg/g leaf tissue for the blood-typing monoclonal antibody C5-1 expressed in MeJA-treated leaves, compared to less than 200 μg/g in untreated leaves. Our data confirm overall the ability of MeJA to trigger RuBisCO depletion and recombinant protein enrichment in N. benthamiana leaves, estimated here for C5-1 at more than 2-fold relative to host proteins.

  17. Geographic variation of floral traits in Nicotiana glauca : Relationships with biotic and abiotic factors

    NASA Astrophysics Data System (ADS)

    Nattero, Julieta; Sérsic, Alicia N.; Cocucci, Andrea A.

    2011-09-01

    Geographic pattern of phenotypic variation can appear in a clinal or a mosaic fashion and can evidence adaptive or non-adaptive variation. To shed light on the mechanisms underlying this variation, we studied the relationships between geographic variation of floral traits and both biotic and abiotic factors of the hummingbird-pollinated plant, Nicotiana glauca, across its natural range. We obtained floral measures of 38 populations from an area about 1600 km long and 1050 km wide and an altitude range from 7 to over 3400 m. We used a MANOVA to detect between-population differentiations in flower traits and a DFA to determine the traits that best discriminate between populations. To test for associations between floral traits and climatic variables we used correlation analysis. We explored any possible distance-based pattern of variation (either geographic or altitudinal) in floral traits or bill length of pollinators using Mantel tests. Finally, we used a multiple regression to analyze simultaneously the effects and relative importance of abiotic predictor variables and bill length on corolla length. We found a high variation in flower traits among populations. Morphometric traits were the ones that best discriminated across populations. There was a clinal pattern of floral phenotypic variation explained by climatic factors. Differences in floral phenotypic distances were structured by altitudinal distances but not by geographic distances. Bill length of the hummingbird pollinators was structured both by altitudinal and geographic distances. Differences in bill length of hummingbird pollinators explained differences in corolla length across populations. Our findings support the assumption of flower evolution at a broad geographic scale. Floral traits seem to be structured not only by altitude but also by climatic factors.

  18. Multiplexed, targeted gene editing in Nicotiana benthamiana for glyco-engineering and monoclonal antibody production.

    PubMed

    Li, Jin; Stoddard, Thomas J; Demorest, Zachary L; Lavoie, Pierre-Olivier; Luo, Song; Clasen, Benjamin M; Cedrone, Frederic; Ray, Erin E; Coffman, Andrew P; Daulhac, Aurelie; Yabandith, Ann; Retterath, Adam J; Mathis, Luc; Voytas, Daniel F; D'Aoust, Marc-André; Zhang, Feng

    2016-02-01

    Biopharmaceutical glycoproteins produced in plants carry N-glycans with plant-specific residues core α(1,3)-fucose and β(1,2)-xylose, which can significantly impact the activity, stability and immunogenicity of biopharmaceuticals. In this study, we have employed sequence-specific transcription activator-like effector nucleases (TALENs) to knock out two α(1,3)-fucosyltransferase (FucT) and the two β(1,2)-xylosyltransferase (XylT) genes within Nicotiana benthamiana to generate plants with improved capacity to produce glycoproteins devoid of plant-specific residues. Among plants regenerated from N. benthamiana protoplasts transformed with TALENs targeting either the FucT or XylT genes, 50% (80 of 160) and 73% (94 of 129) had mutations in at least one FucT or XylT allele, respectively. Among plants regenerated from protoplasts transformed with both TALEN pairs, 17% (18 of 105) had mutations in all four gene targets, and 3% (3 of 105) plants had mutations in all eight alleles comprising both gene families; these mutations were transmitted to the next generation. Endogenous proteins expressed in the complete knockout line had N-glycans that lacked β(1,2)-xylose and had a significant reduction in core α(1,3)-fucose levels (40% of wild type). A similar phenotype was observed in the N-glycans of a recombinant rituximab antibody transiently expressed in the homozygous mutant plants. More importantly, the most desirable glycoform, one lacking both core α(1,3)-fucose and β(1,2)-xylose residues, increased in the antibody from 2% when produced in the wild-type line to 55% in the mutant line. These results demonstrate the power of TALENs for multiplexed gene editing. Furthermore, the mutant N. benthamiana lines provide a valuable platform for producing highly potent biopharmaceutical products.

  19. Expression of Aspergillus nidulans phy gene in Nicotiana benthamiana produces active phytase with broad specificities.

    PubMed

    Oh, Tae-Kyun; Oh, Sung; Kim, Seongdae; Park, Jae Sung; Vinod, Nagarajan; Jang, Kyung Min; Kim, Sei Chang; Choi, Chang Won; Ko, Suk-Min; Jeong, Dong Kee; Udayakumar, Rajangam

    2014-09-03

    A full-length phytase gene (phy) of Aspergillus nidulans was amplified from the cDNA library by polymerase chain reaction (PCR), and it was introduced into a bacterial expression vector, pET-28a. The recombinant protein (rPhy-E, 56 kDa) was overexpressed in the insoluble fraction of Escherichia coli culture, purified by Ni-NTA resin under denaturing conditions and injected into rats as an immunogen. To express A. nidulans phytase in a plant, the full-length of phy was cloned into a plant expression binary vector, pPZP212. The resultant construct was tested for its transient expression by Agrobacterium-infiltration into Nicotiana benthamiana leaves. Compared with a control, the agro-infiltrated leaf tissues showed the presence of phy mRNA and its high expression level in N. benthamiana. The recombinant phytase (rPhy-P, 62 kDa) was strongly reacted with the polyclonal antibody against the nonglycosylated rPhy-E. The rPhy-P showed glycosylation, two pH optima (pH 4.5 and pH 5.5), an optimum temperature at 45~55 °C, thermostability and broad substrate specificities. After deglycosylation by peptide-N-glycosidase F (PNGase-F), the rPhy-P significantly lost the phytase activity and retained 1/9 of the original activity after 10 min of incubation at 45 °C. Therefore, the deglycosylation caused a significant reduction in enzyme thermostability. In animal experiments, oral administration of the rPhy-P at 1500 U/kg body weight/day for seven days caused a significant reduction of phosphorus excretion by 16% in rat feces. Besides, the rPhy-P did not result in any toxicological changes and clinical signs.

  20. Glyphosate inhibition of 5-enolpyruvylshikimate 3-phosphate synthease from suspension-cultured cells of Nicotiana silvestris

    SciTech Connect

    Rubin, J.L.; Gaines, C.G.; Jensen, R.A.

    1984-07-01

    Treatment of isogenic suspension-cultured cells of Nicotiana silvestris Speg, et Comes with glyphosate (N-(phosphonomethyl)glycine) led to elevated levels of intracellular shikimate (364-fold increase by 1.0 millimolar glyphosate). In the presence of glyphosate, it is likely that most molecules of shikimate originate from the action of 3-deoxy-d-arabino-heptulosonate 7-phosphate (DAHP) synthase-Mn since this isozyme, in contrast to the DAHP synthase-Co isozyme, is insensitive to inhibition by glyphosate. 5-Enolpyruvylshikimate 3-phosphate (EPSP) synthase (EC 2.5.1.19) from N. silvestris was sensitive to micromolar concentrations of glyphosate and possessed a single inhibitor binding site. Rigorous kinetic studies of EPSP synthase required resolution from the multiple phosphatase activities present in crude extracts, a result achieved by ion-exchange column chromatography. Although EPSP synthase exhibited a broad pH profile (50% of maximal activity between pH 6.2 and 8.5), sensitivity to glyphosate increased dramatically with increasing pH within this range. In accordance with these data and the pK/sub a/ values of glyphosate, it is likely that the ionic form of glyphosate inhibiting EPSP synthase is COO/sup -/CH/sub 2/NH/sub 2//sup +/CH/sub 2/PO/sub 3//sup 2 -/, and that a completely ionized phosphono group is essential for inhibition. At pH 7.0, inhibition was competitive with respect to phosphoenolpyruvate (K/sub i/ = 1.25 micromolar) and uncompetitive with respect to shikimate-3-P (K/sub i/ = 18.3 micromolar). All data were consistent with a mechanism of inhibition in which glyphosate competes with PEP for binding to an (enzyme:shikimate-3-P) complex and ultimately forms the dead-end complex of (enzyme:shikimate-3-P:glyphosate). 36 references, 8 figures, 1 table.

  1. Reduced gravitropic sensitivity in roots of a starch-deficient mutant of Nicotiana sylvestris

    NASA Technical Reports Server (NTRS)

    Kiss, J. Z.; Sack, F. D.

    1989-01-01

    Gravitropism was studied in seedlings of Nicotiana sylvestris Speg. et Comes wild-type (WT) and mutant NS 458 which has a defective plastid phosphoglucomutase (EC 2.7.5.1.). Starch was greatly reduced in NS 458 compared to the WT, but small amounts of starch were detected in rootcap columella cells in NS 458 by light and electron microscopy. The roots of WT are more sensitive to gravity than mutant NS 458 roots since: (1) in mutant roots, curvature was reduced and delayed in the time course of curvature; (2) curvature of mutant roots was 24-56% that of WT roots over the range of induction periods tested; (3) in intermittent-stimulation experiments, curvature of mutant roots was 37% or less than that of WT roots in all treatments tested. The perception time, determined by intermittent-stimulation experiments, was < or = 5 s for WT roots and 30-60 s for mutant roots. The growth rates for WT and NS 458 roots were essentially equal. These results and our previous results with WT and starchless mutant Arabidopsis roots (Kiss et al. 1989, Planta 177, 198-206) support the conclusions that a full complement of starch is necessary for full gravitropic sensitivity and that amyloplasts function in gravity perception. Since a presumed relatively small increase in plastid buoyant mass (N. sylvestris mutant versus Arabidopsis mutant) significantly improves the orientation of the N. sylvestris mutant roots, we suggest that plastids are the likeliest candidates to be triggering gravity perception in roots of both mutants.

  2. Genetic processes in intergeneric cell hybrids Atropa + Nicotiana : 1. Genetic constitution of cells of different clonal origin grown in vitro.

    PubMed

    Gleba, Y Y; Momot, V P; Okolot, A N; Cherep, N N; Skarzhynskaya, M V; Kotov, V

    1983-06-01

    The genetic constitution of the cell hybrids Atropa belladonna + Nicotiana chinensis, obtained by cloning of individual heteroplasmic protoplast fusion products (Gleba et al. 1982) and cultured in vitro for 12 months, has been studied. The study comprised 11 hybrid cell clones of independent origin and included analysis of a) chromosome number, size, morphology, and relative position in metaphase plates, b) multiple molecular forms of the enzymes esterase and amylase, and c) relative nuclear DNA content. The data obtained permit us to conclude that, after one year of unorganized growth in vitro, the cells of most (8) clones had retained chromosomes of both parents, while species-specific elimination of nearly all Atropa chromosomes had occurred in three clones. About half of the non-segregating clones possess 120-150 chromosomes including 50-70 of Atropa and 50-90 of Nicotiana. Other clones are polyploid and possess 200-250 chromosomes with a predominance of either Atropa or Nicotiana chromosome types. Only a few chromosomal changes (reconstituted chromosomes, ring chromosomes) have been detected. In some metaphase plates, chromosomes of the two parents tend to group separately, indicating non-random arrangement of chromosomes of the two parents within the hybrid nucleus. Cytophotometric studies of the relative nuclear DNA content showed that distribution histograms for cell clones were similar to those of non-hybrid cultured cells. Cell populations were relatively homogenous and do not indicate any genetic instability as a result of hybridization between remote plant species. Biochemical analysis of iso