Effect of cultivation temperature on peroxidase isozymes of plant cells grown in suspension

Phenotypical Temperature Adaptation of Protein Synthesis in Wheat Seedlings : QUALITATIVE ASPECTS. INVOLVEMENT OF AMINOACID:tRNA-LIGASES

Phenotypical temperature adaptation of protein synthesis in wheat (Triticum aestivum L.) seedlings is not affected by darkness (etiolation), by partial inhibition of protein biosynthesis (10(-3)m fluorophenylalanine), or by changing the amino acid precursor and the radioisotope ([(3)H]valine instead of [(14)C]leucine). The temperature coefficient (mu), as well as the optimum temperature of in vivo protein synthesis, increases with rising preadaptation temperature, as normally observed. Protein turnover studies revealed that only proteins with a short half-life time (t((1/2)) = 2 to 4 hours) are labeled to a measurable extent during the temperature adaptation experiments. A heat-labile protein has been detected and partially characterized by means of polyacrylamide gradient gels. Leucine:tRNA-ligase (EC 6.1 1.4) from heat-pretreated wheat seedlings exhibits enhanced thermal stability. In Arrhenius curves, the upper transition point shifts from 30 to 34 degrees C, depending on preadaptation temperature. Only the leucine:tRNA-ligase extracted from heat-adapted plants is stable when the enzyme extracts are subjected to a 34 degrees C heat treatment.

Phenotypical temperature adaptation of protein synthesis in wheat seedlings: time curves for readaptation

Optimum temperature and temperature coefficient of protein synthesis in young wheat plants exhibit phenotypical temperature adaptation. In plants grown for 2 days at either chilling (4 C), medium (20 C), or high (36 C) temperature the respective values are: 27 C and 14.2 kilocalories per mole, 31 C and 18.2 kilocalories per mole, 35 C and 23.6 kilocalories per mole, based on in vivo [(14)C]leucine incorporation into total protein. The validity of the [(14)C]leucine incubation method has been confirmed by double-labeling experiments. Readaptation time curves are complex: the optimum temperature parameter readjusts within approximately 4 hours to an altered temperature regime, whereas the temperature coefficient needs between 4 and 96 hours for complete readaptation-depending on the temperature conditions prior to the temperature shift. Heat-preadapted plants need a recovery period at medium temperature to regain their cold adaptability with respect to optimum temperature. Cycloheximide (30 micrograms per milliliter) reduces [(14)C]leucine incorporation into protein by 85%, thus indicating that predominantly the cytoplasmic 80S system of protein synthesis is involved in temperature adaptation.

Identification by physical means of organic moieties of conjugates produced from carbaryl by tobacco cells in suspension culture

Carbaryl (1-naphthyl methylcarbamate), labeled with 14C in the C1-naphthyl, carbonyl, or N-methyl position, was introduced into the culture medium of tobacco cells in suspension culture. Following incubation, cells were homogenized in water, centrifugated, and supernatants hydrolyzed with beta-glucosidase or HCl. Organic moieties (moieties) were characterized by two-dimensional thin-layer chromatography (TLC), and many were subsequently identified by infrared and mass spectrometry. On the basis of the data obtained with 14C1-naphthyl-labeled carbaryl, it appeared that 18.4% of the total characterized metabolites represented unconjugated N-CH2OH- carbaryl [1-naphthyl N-(hydroxymethyl)carbamate], excreted by the cells into the culture medium. The metabolites found in the cells primarily consisted of conjugates of 1-naphthol (73.6% of the total characterized metabolites) and N-CH2OH-carbaryl (2.5%). Conjugates of 7-hydroxycarbaryl (7-hydroxy-1-napthyl methylcarbamate), 4-hydroxycarbaryl (4-hydroxy-1-naphthyl methylcarbamate), and 5-hydroxycarbaryl (5-hydroxy-1-naphthyl methylcarbamate) were also detected in small amounts. Of five unknown 14C1-naphthyl-labeled carbaryl metabolites, three were tentatively characterized as: O-1-naphthylcholesterol (Cholest-5-en-3beta-yl-1-napthol: 3.0%); an unconjugated hydroxylated 1,4-dihydro-1,4-epiperoxynapththalene (1.4%); and an acidlabile, beta-glucosidase-resistant conjugate of a cis-dihydrodiol of 1-naphthol (0.3%; other than the trans-5,6-dihydrodiol). The cholesterol derivative may represent a new "detoxification mechanism" in plants; the epiperoxide may help to elucidate plant oxidation mechanisms. A new TLC procedure was developed which successfully separated the acetate derivative of N-hydroxycarbaryl (1-naphthyl N-hydroxy-N-methylcarbamate) from 12 other common moieties of carbaryl metabolites and their acetate derivatives. A new two-dimensional TLC system was developed for the separation of underivatized N-hydroxycarbaryl from 14 other moieties of carbaryl metabolites; two additional two-dimensional TLC systems were utilized for moiety separations. With these TLC procedures, no conjugated or unconjugated N-hydroxycarbaryl could be detected in any tobacco cell culture fraction after incubation of cells in medium containing radiolabeled carbaryl. Authentic 14C1-naphthyl-labeled N-CH2OH-carbaryl was shown to be converted to desmethylcarbaryl (1-naphthylcarbamate) 97%) and 1-naphthol (3%) by 0.1N HCl hydrolysis.

Detergent extraction of enzymes from tobacco leaves varying in maturity

Enzyme activities of tobacco leaves were compared in detergent extracts. Highest levels of chlorogenic acid oxidase, malate-NAD oxidoreductase, and acid phosphatase were obtained from bud tissues. Peroxidase activity was least in young leaves and highest in senescent leaves yellowed with Ethrel. Peroxidase zymograms obtained by means of disc electrophoresis showed differences in isozyme composition among all five samples examined. Although protease was found in material extracted from buds, upper, middle, and lower leaf positions, none could be demonstrated in Ethrel-treated mature leaves.

Hybridization of some Trifolium species through stylar temperature treatments

Plants of seven perennial Trifolium species were interspecifically pollinated. The female flowers opened at 40 °C, and the male flowers opened in the greenhouse or field without a temperature treatment. T. pratense was pollinated with T. ambiguum, T. hirtum, T. ochroleucum, T. rubens, T. sarosiense, and T. medium. T. medium was pollinated with T. pratense. Seeds were obtained from all pollinations ; however, 86 of the progeny were morphologically and cytologically similar to their female parent, and probably resulted from self-fertilization. Many seeds of possible hybrid origin were small and/or did not germinate. Some seeds produced weak or albino seedlings which died at an early age. Excised pistils of T. medium from flowers that opened at 40 °C were more compatible with pollen of T. pratense than pistils of T. medium that developed in the field, indicating that the elevated temperature caused greater hybrid seed production than was observed in our earlier studies. The high temperature technique may prove useful in obtaining hybrids in Trifolium.

Peroxidases in the genus Nicotiana

Leaf peroxidases of 60 Nicotiana species, 19 cultivars, autopolyploids, interspecific hybrids, and amphidiploids have been compared by polyacrylamide gel block electrophoresis. At least 19 peroxidase bands, four cathodic and 15 anodic, were detected in the species which varied from two bands in N. arentsii to 12 bands in N. tabacum. Tihe cultivars of the latter species failed to reveal any intraspecific variation. Specific difference and varietal resemblance in root peroxidase bands were also observed in nine species and 20 varieties analyzed. Zymograms from autopolyploids and amphidiploids appeared to be identical to that of diploid parents, suggesting that peroxidase banding patterns are independent of ploidy levels. An additive manner of parental peroxidase bands without hybrid enzyme formation in interspecific hybrids and the failure of dissociating peroxidases into subunits lead to a hypothesis that peroxidases in Nicotiana may be controlled by multiple, dominant genes and/or codominant alleles in chromosomes of different genomes. This is in keeping with the lack of relationship between ploidy level and peroxidase banding pattern. Also, species with different chromosome numbers shared many peroxidases in common that possibly reflects a residual homology of peroxidase loci among Nicotiana species. Some species classified in different sections or subgenera but having a common geographic center of origin, showed close similarities in peroxidase zymogram. Results suggest that these species may be closely related in phylogeny, and/or geographic isolation changes the peroxidase genes through mutation and selection. Based on leaf peroxidase zymograms of F 1 hybrids, a putative ancestor of N. tomentosiformis was the progenitor of N. tabacum at its inception.

Herbicide metabolism in plants: specificity of peroxidases for aniline substrates

Images

Plant suspension culture media macromolecules-pectic substances, protein, and peroxidase

Macromolecules secreted into the media by a nondifferentiating suspension culture of tobacco cells were found to be composed of protein and polysaccharide, and to account for the viscosity of the media. The concentration, composition, and viscosity of these macromolecules changed significantly with the age of the culture and growth temperature. The concentration changed from 0.02 mg/ml in newly inoculated cultures to over 1 mg/ml in older cultures. The macromolecules contained from 6 to 18% protein and 3 to 4 mumoles hydroxy-proline/mg nitrogen, more than 20 times the level found in whole cells. The macromolecules contained 5 to 25% pectic substances whose carboxyl groups were either methyl esterified or combined with calcium. Arabinose, xylose, glucose, galactose, and mannose were identified in acid hydrolysates of the macromolecules. Peroxidase activity of the macromolecules increased as cultures became older. Peroxidase isoenzyme patterns changed with culture age and growth temperature. The relation of the macromolecules to cell walls and intercellular substances is discussed.

Rapid technique for enumeration and isolation of peroxidase-producing microorganisms

Peroxidase-positive microorganisms were enumerated on agar plates by use of a p-anisidine-H(2)O(2) spray. Combined with replica-plating, the same technique allowed the selective isolation of peroxidase-producing microbial cultures.