Impact of magnetically treated water on the growth and development of tobacco ( Nicotiana tabacum var. Turkish)

Magnetism is one of the physical methods affecting water properties. It is considered as an environmental factor that plays a role in the physiological and biochemical reactions. A hydroponic experiment was conducted using four types of treated water (distilled water, magnetically treated distilled water, magnetically treated tap water, and tap water). Tobacco plants (Nicotiana tabacum var. Turkish) were placed in a growth chamber for three weeks. Plants irrigated with magnetically treated distilled water had a significant increase in the physiological parameters including shoot height and root length (P < 0.0001). The same pattern was seen in the photosynthetic rate and protein content, but no significant differences in the stomatal conductance and transpiration rate (P < 0.5601). In contrast, a significant increase of total carbohydrate content was exhibited in plant irrigated with tap water (P < 0.0064). Electron micrographs showed deformed chloroplasts with damaged thylakoid membranes associated with plastoglobules in plants irrigated with tap water and magnetically treated tap water. Lastly, this study suggests that magnetically treated water is an excellent option to improve irrigation methods and thus obtains agricultural production with high efficiency.     

Transmission of paternal chloroplasts in tobacco (Nicotiana tabacum)

Medgyesy et al. (1986, Mol. Gen. Genet. 204, 195–198) have described in Nicotiana plumbaginifolia and in an interspecific cross involving N. plumbaginifolia and N. tabacum a procedure for selecting cell lines derived from seedlings carrying paternal chloroplasts by taking advantage of a plastid-encoded mutation which confers resistance to streptomycin. We have extended their demonstration of occasional transmission of chloroplasts through pollen to the case of an intraspecific cross in N. tabacum. The line used as maternal parent, ITB19(sua), displayed a cytoplasmic male sterility due to the presence of a cytoplasm originating from N. suaveolens. The line used as paternal parent, SR1, was fertile and possessed mutant chloroplasts conferring resistance to streptomycin. From cell lines derived from 204 seedlings, three were regenerated into streptomycin-resistant buds. The plants derived from these three clones were male-sterile. Their progeny, after crossing with a wild type tobacco line, XHFD8, was resistant to streptomycin. Tests of resistance of the seedlings to tentoxin and restriction analyses of the chloroplast DNA indicated that two clones still had the maternal chloroplasts and were thus probably new streptomycin-resistant mutants, whereas the third one had acquired the chloroplasts of the paternal parent, but had retained the mitochondria of the maternal parent.Abbreviations cp-DNA chloroplast DNA - mt-DNA mitochondrial DNA - Np Nicotiana plumbaginifolia - Nt Nicotiana tabacum     

Purine metabolism in mesophyll protoplasts of tobacco (Nicotiana tabacum) leaves.

The overall metabolism of purines was studied in tobacco (Nicotiana tabacum) mesophyll protoplasts. Metabolic pathways were studied by measuring the conversion of radioactive adenine, adenosine, hypoxanthine and guanine into purine ribonucleotides, ribonucleosides, bases and nucleic acid constituents. Adenine was extensively deaminated to hypoxanthine, whereupon it was also converted into AMP and incorporated into nucleic acids. Adenosine was mainly hydrolysed to adenine. Inosinate formed from hypoxanthine was converted into AMP and GMP, which were then catabolized to adenine and guanosine respectively. Guanine was mainly deaminated to xanthine and also incorporated into nucleic acids via GTP. Increased RNA synthesis in the protoplasts resulted in enhanced incorporation of adenine and guanine, but not of hypoxanthine and adenosine, into the nucleic acid fraction. The overall pattern of purine-nucleotide metabolic pathways in protoplasts of tobacco leaf mesophyll is proposed.     

Coproporphyrinogenase in tobacco (Nicotiana tabacum L.)

1. Coproporphyrinogenase was extracted and purified from tobacco (Nicotiana tabacum L.). Enzyme activity was mainly located in mitochondria rather than in chloroplasts. The enzyme was purified by differential centrifugation, ammonium sulphate fractionation, calcium phosphate gel adsorption and dialysis. A 69-fold final purification was obtained. 2. An apparent K(m) value of 3.6x10(-5)m was found, the value being largely dependent on the amount of coproporphyrin III recovered after reduction with sodium amalgam to coproporphyrinogen III. Protoporphyrin formation was linear up to 3h and decreased with further incubation. The enzyme activity increased with the concentration of enzyme protein up to 30mug/ml of solution. 3. Enzyme activity was greatly enhanced by increasing Fe(2+) concentrations up to 0.5mm, beyond which inhibition occurred. Co(2+) and Mn(2+) were also found to activate at low concentrations (0.1mm) and inhibit at higher concentrations (5mm). Fe(3+) and Cu(2+), both at 0.1mm, and o-phenanthroline and EDTA, each at 1mm, were found to be inhibitory.     

Dynamic landscape of mitochondrial Cytidine-to-Uridine RNA editing in tobacco (Nicotiana tabacum) shows its tissue specificity

Plant Cell, Tissue and Organ Culture (PCTOC) - RNA editing is a prevalent nucleotide modification at the RNA level in higher plants. However, little is known about the dynamic distribution of RNA...     

CO2 enrichment in vitro. Effect on autotrophic and heterotrophic cultures of Nicotiana tabacum (var. Samsun)

Summary Plantlets of Nicotiana tabacum (var. Samsun) were grown under CO₂ enriched air supplied by a Warburg buffer. Growth of all plant parts was enhanced. The maximum growth increase was found for roots (120%).Addition of 30 g.l^-1 sucrose in the medium resulted in a three time faster growth. However, the effect of CO₂ enrichment was still positive in these conditions, although less pronounced than in autotrophic cultures.     

Nonstructural carbohydrate metabolism during leaf ageing in tobacco (Nicotiana tabacum)

Nonstructural carbohydrate status and activities of ADP-glucose pyrophosphorylase (EC 2.7.7.27, ADPG pyrophosphorylase) and sucrose phosphate synthase (EC 2.4.1.14, SPS) were determined during ageing of tobacco ( Nicotiana tabacum L., cvs KY 14 and Speight G28) leaves sampled from control plants and from plants that had the apical meristem and subsequent axillary growth removed (detopped plants). Over the 30-day period shoot growth increased much more for control compared to detopped plants, but the increase in root growth was similar for both treatments. Dry matter and leaf area of the individual leaf used for enzyme and metabolite analysis were constant over time for controls but increased 5-fold for detopped plants. Ageing of control leaves was indicated by a progressive loss of chlorophyll and ribulose 1, 5-bisphosphate carboxylase (EC 4.1.1.39, Rubisco) activity; loss of these components was diminished for detopped plants. In contrast to chlorophyll and Rubisco activity, activities of ADPG pyrophosphorylase and SPS remained relatively constant over time for controls. Thus, under normal ageing conditions, changes in activities of ADPG pyrophosphorylase and SPS were not closely associated with changes in the standard senescence indicators chlorophyll and Rubisco activity. The activities of ADPG pyrophosphorylase and SPS were enhanced, relative to controls, within 6 days after applying the detopping treatment and activities remained high for the duration of the 30-day period. Detopping also led to increased concentrations of starch and sucrose, but the increases were not well correlated with changes in enzyme activities. The data indicated that the leaves of detopped plants functioned as both source leaves, with enhanced ability to synthesize carbohydrate, and sink leaves, with enhanced growth. Therefore, activities of ADPG pyrophosphorylase and SPS were more responsive to changes within an individual leaf than to changes in whole plant growth.     

Preliminary study of Lead (Pb) immobilization by meat and bone meal combustion residues (MBMCR) in soil: Assessment of Pb toxicity (phytotoxicity and genotoxicity) using the tobacco model (Nicotiana tabacum var. xanthi Dulieu)

Lead (Pb) is a major chemical pollutant in the environment. The present investigation evaluates the possible use of Meat and Bone Meal Combustion Residues (MBMCR), to sequester Pb from the soil compartment using the heterozygous tobacco model (Nicotiana tabacum var. xanthi Dulieu) characterized by the a1+ /a1 a2+ /a2 system. The toxic potential of Pb-contaminations (50, 100, 1,000, 2,000 and 10,000 mg Pb kg(-1)) as Pb(NO3) in standard soil was investigated in lab conditions according to three endpoints: (i) acute toxicity of plants (mortality, height and surface area parameters), (ii) Pb-accumulation in roots, stems and leaves, and (iii) genetic effects as the expression of reversion in the leaf of plants. Moreover, chemical investigations of Pb interactions with soil were realized to complete the toxicity evaluation. The results demonstrated that: (i) MBMCR were not acutely toxic or genotoxic to tobacco plants, (ii) Pb is acutely toxic to tobacco plants at 10,000 mg Pb kg(-1) of soil, (ii) but is not genotoxic, and (iii) Pb-bioaccumulation is significant in leaves, stems and roots (from 1,000, 2,000, and 50 mg Pb kg(-1) of soil, respectively). In contrast, in the presence of MBMCR, the toxic impacts of Pb were inhibited and Pb-accumulation in tobacco plants was reduced. In complement, chemical analyses highlighted the high capacity of the standard soil to immobilize Pb. The results suggest that even if Pb is bioavailable from soils to plants, complex mechanisms could occur in plants protecting them from the toxic impact of Pb.     

DNA changes during sequential leaf senescence of tobacco (Nicotiana tabacum)

Age related DNA changes in tobacco (Nicotiana tabacum) leaf nuclei were investigated by Feulgen cytophotometry, thermal denaturation, renaturation, and DNA-DNA hybridization studies during sequential leaf senescence. Cytophotometric Feulgen-DNA comparison measurements between young and senescing nuclei displayed 18% reduction in Feulgen-DNA values, with a corresponding decrease in nuclear area in senescing nuclei. Hydrolysis kinetics indicated that the loss was not due to compactness of the DNA as the curves for older nuclei were consistently lower than curves generated from younger nuclei. DNA loss in senescing nuclei was associated with a decrease in euchromatin or shift from euchromatin to facultative heterochromatin. Purified DNA from young and senescing leaf nuclei did not display different thermal profiles nor did hydroxylapatite chromatography reassociation curves. DNA-DNA hybridization in free solution from young and senescing leaf DNA performed by a Gilford thermo-programmer system indicated that DNA of senescing tobacco nuclei reassociated more slowly than DNA from young nuclei and the mixture of young and senescing leaf DNA displayed intermediate reassociation values. The study indicates that the DNA changes during senescence involve a complex phenomenon which includes the possibility of small single strand nicks undetectable by thermal denaturation, and a loss of small double strand fragments which were detectable only by precise DNA-DNA free solution reassociation and not by hydroxylapatite chromatography reassociation.     

Molecular characterization of profilin isoforms from tobacco (Nicotiana tabacum) pollen

Profilins are actin-binding proteins in eukaryotes which participate in the phosphoinositide pathway via binding to PIP₂. Using polyclonal rabbit sera raised against plant profilins, the occurrence of several profilin isoforms is demonstrated in two-dimensionally analyzed tobacco pollen extracts. The cDNAs coding for two novel tobacco profilin isoforms (ntPro2, ntPro3) were isolated from a pollen cDNA library by antibody screening. When the cDNA and deduced amino acid sequences of the two isoforms were compared with a previously isolated tobacco pollen profilin cl)NA (ntPro1), significant differences were noted in the non-coding regions, whereas the coding sequences, in particular the functional domains, showed little variation. The cDNAs coding for the three tobacco profilin isoforms were expressed inEscherichia coli and shown to bind comparably to different anti-profilin antisera. The high degree of similarity among the different tobacco pollen profilin isoforms points to functional equivalence. Assuming that the presence of profilin is indispensable to the control of the large amounts of actin present in pollen, the occurrence of different profilin isoforms in pollen is interpreted to represent a protective mechanism against loss of profilin functions.     

Effects of ribavirin and adenine arabinoside on tobacco mosaic virus in Nicotiana tabacum L. var Xanthi tissue cultures

Although both ribavirin (1-β-ribofuranosyl-1,2,4-triazole-3carboxamide) and adenine arabinoside inhibited the multiplication of tobacco mosaic virus (TMV) in mechanically inoculated leaf tissues, neither chemical inhibited virus multiplication in unorganized tobacco callus after in vitro inoculation. The adenine deaminase inhibitor, pentostatin, did not increase the activity of adenine arabinoside in cultured cells. Several different developmental conditions and media did not increase the ability of either chemical to eradicate the virus from tobacco tissue cultures. However, the virus was eradicated from TMV-infected callus when grown in the presence of combinations of ribavirin and adenine arabinoside in shoot inducing medium.     

Cell-wall-bound oxidases from tobacco (Nicotiana tabacum) xylem participate in lignin formation

A band of cells closest to the cambium in the xylem of tobacco (Nicotiana tabacum L. cv. Samsun) stems oxidized 2,2-azinobis-(3-ethylbenzo-thiazoline-6-sulphonate) (ABTS), o-dianisidine and syringaldazine in the absence of exogenously added hydrogen peroxide. The oxidation was not prevented by catalase which suggests that the oxidation is not dependent on the production and utilisation of endogenous hydrogen peroxide by cell-wall peroxidases. Cell walls, isolated from tobacco xylem, also oxidized these substrates in the absence of added hydrogen peroxide. The cell walls consumed molecular oxygen whilst oxidizing a range of compounds including coniferyl alcohol. The substrate preference and sensitivity to inhibitors suggest the presence of laccasetype polyphenol oxidases (p-diphenol:O₂ oxidoreductase EC 1.14.18.1) which are covalently bound to the wall. The oxidation of coniferyl alcohol by the xylem cell walls was confirmed by assays based on the disappearance of coniferyl alcohol and was not affected by the presence of 500 units·mi^-1 catalase or Superoxide dismutase. Prolonged incubation of cell walls with coniferyl alcohol led to the production of a yellow-orange water-insoluble material that precipitated with the cell walls. Although a proportion of this material was soluble in methanol, the majority was tightly associated with the cell walls. These coloured cell walls had elevated lignin contents when assayed by the acetyl-bromide method. Fourier transforminfrared spectroscopic analysis of the coloured cell walls indicated that the increased lignin content is due to the deposition of guaiacyl-type lignin. Digestion of the xylem cell walls with Driselase, a mixture of fungal glycases, produced a wall residue that had a dramatically reduced ability to oxidize ABTS in the absence of added H₂O₂. However, oxidase activity could not be detected in the Driselase-solubilized extract, although small amounts of oxidase activity could be recovered from the Driselaseresistant wall residue by extraction in 3 M CaCl₂.Abbreviations ABTS 2,2-azinobis-(3-ethylbenzo-thiazoline-6-sulphonate) - dl-DOPA 3-(3,4-dihydroxyphenyl)-alanine - FTIR Fourier transform infra-red - o-D o-dianisidine - o-pD o-phenylenediamine - SYR syringaldazine The authors acknowledge funding from the Scottish Office Agriculture and Food Department. They would like to thank Professor J.R. Hillman for his support, Dr. G.D. Lyon for his help and advice with the oxygen electrode and Mrs F. Carr for lignin determinations.     

Effect of Ethephon on stomatal opening in detached epidermal strips of tobacco leaves (Nicotiana tabacum L. cv. Samsun)

The effect of Ethephon preparations upon stomatal openings in detached epidermal strips of tobacco leaves floated on 0.1 M KC1 was measured microscopically after different times of exposure. Addition of 0.01 v/v % or 0.1 v/v % Camposan, Ethrel, or E-BOH resulted in the opening or closing of the stomata depending upon the time of exposure and the concentration of Ethephon. It is evident from the results obtained in these studies that an increase in stomatal opening was induced by the acidity of the preparations and the released ethylene too. Prolonged times of action resulted in decreased stomatal openings or in stomata being closed, respectively. High concentrations of Ethephon also resulted in major damage being caused to guard cells after having been permitted to act upon them for an extended period of time.     

Mismatch-specific DNA breakdown in nuclear extract from tobacco (Nicotiana tabacum) callus

Mismatch-specific enzymatic activity was sought for in nuclei from normal and transformed plant cells originating from tobacco (Nicotiana tabacum) callus and crown gall tumor induced by Agrobacterium tumefaciens. The specific enzymatic activity was assayed with substrates derived from synthetic oligonucleotides (19-mer sequences corresponding to the human K-ras gene). Single-base changes in the middle of the sequence were the basis for creating heteroduplexes with all eight mismatches. Homo- and heteroduplexes were ligated in a size ladder and used as substrates. We detected mismatch-specific DNA breakdown and determined basic requirements for the reations. Kinetic analysis indicates the following reactivity order of preference: C : A=C : C=C : T>G : TA : AG : AG : GT : T>>G : C. It can be said now that specific mismatch recognition and repair activities have been detected in all kingdoms of living species.     

Immunoreactive and bioactive somatostatin-like material is present in tobacco (Nicotiana tabacum)

Immunoreactive and biologically active somatostatin-like material is present in extracts of tobacco plants (Nicotiana tabacum). Comparative chromatographic and immunological characterization of this peptide along with synthetic (hypothalamic-like) somatostatin-14 and -28, indicates that both molecular forms are present in the plant. Tobacco-somatostatin inhibits the prostaglandin E2-induced release of growth hormone from cultured anterior pituitary cells. This finding raises questions concerning the evolutionary mechanisms responsible for the presence of this neuropeptide in plants, and the physiological significance of this phenomena.     

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

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.