<i>De Novo</i> Synthesis of Peroxidase Isozymes in Sweet Potato Slices

Shannon, Leland M.; Uritani, Ikuzô; Imaseki, Hidemasa

doi:10.1104/pp.47.4.493

Cited by 55 publications

(14 citation statements)

References 25 publications

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“…The effect of ethylene on plant enzyme systems such as peroxidase has been well documented (11,12,16,31); for example, peroxidase in sweet potato slices increased 100-fold after exposure to low ethylene concentrations (34 (Figs. 1-4) was studied until separation was complete.…”

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confidence: 99%

“…Deblading of bean leaves resulted in an increase in peroxidase activity in the abseission zone 2 to 4 days after deblading with highest activity just prior to separation. In debladed plants, the Peroxidase has been implicated in a number of diverse phenomena observed in plants (29,31,34,35) including the synthesis of ethylene (21,38). Similarly, conflicting reports (10,18) indicate that ethylene synthesis is not regulated by peroxidase.…”

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confidence: 99%

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Peroxidase Activity in the Abscission Zone of Bean Leaves during Abscission

Poovaiah

Rasmussen

1973

Plant Physiol.

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Peroxidase activity and localization in the abscission zone of bean leaves were studied histochemically and by gel electrophoresis. Deblading of bean leaves resulted in an increase in peroxidase activity in the abseission zone 2 to 4 days after deblading with highest activity just prior to separation. In debladed plants, the Peroxidase has been implicated in a number of diverse phenomena observed in plants (29,31,34,35) including the synthesis of ethylene (21,38). Similarly, conflicting reports (10,18) indicate that ethylene synthesis is not regulated by peroxidase. The localized increase in protein and RNA synthesis necessary for separation to occur in the abscission zone of Phaseolus vulgaris is increased by ethylene (2) and has been associated with an increase in cellulase activity (1,15,26).The effect of ethylene on plant enzyme systems such as peroxidase has been well documented (11,12,16,31) (Figs. 1-4) was studied until separation was complete. Reagents for the localization of peroxidase (8,29) were: 1% H202 and a 70% ethanol solution of 0.1 M benzidine. The peroxidase reaction was carried out on a glass slide. A drop of each reagent was placed in contact with the fresh tissue slice. The sections were incubated for 1 to 2 min, the resulting bubbles were removed by rinsing twice with distilled water, and color photographs were taken immediately to record enzyme localization. Potassium cyanide (0

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confidence: 99%

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confidence: 99%

Peroxidase Activity in the Abscission Zone of Bean Leaves during Abscission

Poovaiah

Rasmussen

1973

Plant Physiol.

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“…One approach aimed at elucidating mechanisms whereby ethylene exerts its effects on plant tissues has been to investigate its effect on RNA and protein synthesis (1), and on the level and activity of various enzymes (5,7,9,10,17,19). In these studies evidence was presented for the induction by ethylene of de novo synthesis of enzymes and increased enzymatic activity.…”

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confidence: 99%

Ethylene-induced Phenylalanine Ammonia-Lyase Activity in Carrot Roots

Chalutz

1973

Plant Physiol.

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Ethylene enhanced the activity of phenylalanine ammonialyase in carrot (Daucus carota L., var. "Nautv") root tissue. Slight increase in enzyme activity was exhibited by root discs incubated in ethylene-free air. It was probably due to the ethylene formed within the sliced tissue. Addition of ethylene to the air stream increased phenylalanine ammonia-lyase activity and the total protein content of the discs until maximum activity was reached after 36 to 48 hours of incubation. (4,8,10,15,16 'Abbreviation: PAL: phenylalanine ammonia-lyase.MATERIALS AND METHODS Fresh carrot (Daucus carota L., var. "Nanty") roots of uniform size were washed in detergent and water and surface sterilized with 70% ethanol. Uniform discs (1 cm thick and 1.5 cm in diameter) were cut from the roots and placed on moist filter paper in open Petri plates. About 50 discs were incubated at 20 C in the dark, inside 20-liter glass jars through which air, ethylene-air, and other gaseous mixtures saturated with water were continuously passed at a rate of 100 ml/min.For nucleic acid and protein synthesis inhibitor studies, discs were dipped for 1 min into the inhibitor solution, then placed on filter paper in Petri plates which contained 2 ml of the inhibitor solution.Acetone powders were prepared from the root discs by cutting the tissue into small pieces and placing 50-g tissue in 500 ml of acetone previously chilled to -18 C. The acetone was changed twice within a period of 1 hr. The tissue was then homogenized for 3 min, filtered through a Whatman No. 1 filter paper in a Buchner funnel, and rinsed with two 500-ml portions of chilled acetone. Mats were dried for 1 hr at room temperature, then kept overnight under vacuum, and stored at -18 C.PAL activity in acetone powders was assayed by the method of Rahe et al. (14) with slight modifications. PAL was extracted by suspending 0.5 g of powder in 10 ml of cold 0.1 M borate buffer, pH 8.8. The suspension was kept in an ice bath for 1 hr with occasional stirring and centrifuged at 40,000g for 20 min at 1 C. The supernatant served as the enzyme preparation. For the assay, 1.5 ml of the supernatant was added to a test tube containing 1.0 ml of 0.05 M L-phenylalanine and 2.5 ml of 0.1 borate buffer, pH 8.8. The assay mixture was incubated in a water bath at 40 C for 1 hr, the reaction was stopped by the addition of 0.1 ml of 5 N HCl, and the acidified mixture was extracted with 7 ml of ether. Two and one-half ml of the ether phase were evaporated to dryness, and the residue was dissolved in 2.5 ml of 0.05 N NaOH. The concentration of cinnamic acid was determined by absorbance at 269 nm, with 0.05 N NaOH as reference. Two controls were run in each assay; a no-substrate assay in which 1.0 ml of deionized water was substituted in the reaction mixture for the L-phenylalanine solution and a zero time stop reaction assay mixture acidified at zero time of incubation. Both controls were assayed as described above. Values obtained from the zero time incubation were applied in the determination of PAL ac...

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“…Thus, the observed inhibitory effect of cycloheximide could be an indirect one related to processes which are triggered by injury, perhaps including the formation of a wound hormone and proteinase inhibitor (8,14). A more direct proof of synthesis de novo of isoperoxidases, enhanced by injury and C2H4, was given for sweet potato roots using blasticidin S and '4C-leucine (16). In injured horseradish roots, cycloheximide inhibited '4C-leucine incorporation into the peptide portion of isoperoxidases, but had little effect on the incorporation of neutral sugars (10).…”

Section: Discussionmentioning

confidence: 99%

Cell Isoperoxidases in Sweet Potato Plants in Relation to Mechanical Injury and Ethylene

1976

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Leaves and storage roots of sweet potato plants (Ipomea batatas) showed the same qualitative isoperoxidase patterns and a similar distribution of distinctive isoperoxidases between the cell protoplast and cell wall free, ionically bound, and covalently bound fractions. No changes in the qualitative isoenzyme spectrum were found in relation to age, mechanical injury, or ethylene action. Thus, as in tobacco plants, the cell isoperoxidases in sweet potato did not reflect the possible differential mRNA synthesis in relation to organ, age, or injury. Transcription does not seem to be a limiting factor in injury-and ethylene-dependent peroxidase enhancement during the first 24 hr.The contribution of the wall ionically bound and protoplast fractions was highest in young and old leaves, respectively. In the protoplast and wall ionically and covalently bound fractions, 14, 6, and 5 isoenzyme bands were found; in addition, 4 bands, not detected in the protoplast, were also revealed in the covalently bound fraction. The distinctive "juvenile" and, developing with age, "mature" isoforms were mainly found in the ionically bound and protoplast fractions, respectively.The injury-enhanced and/or ethylene-enhanced peroxidase development was most pronounced in young leaves. Ethylene suppressed some injury-enhanced, had no effect on some other injury-enhanced, and greatly promoted some of the injury-unaffected or enhanced isoperoxidases. After ethylene removal, an increase in the "mature" isoforms was found in the protoplast of intact leaves.Electron microscopy of leaves revealed peroxidase in membrane-bound vesicles located mainly in the vacuole; a thin layer of reaction products was also found on the wall's outer surface. No Golgi apparatus were seen in the ceUs of control or ethylene-treated intact leaves. In ethylenetreated intact or injured leaves accumulations of reaction products between the plasmalemma and wall were also found. Numerous Golgi apparatus with dark stained vesicles were seen in injured, and especially in injured and ethylene-treated leaves; the vacuolar bodies seemed to occur in very great number.Previous investigation (2-4) has shown that sweet potato storage roots differ significantly from tobacco pith and leaves and carrot roots in the peroxidase reaction to mechanical injury, C2H4, IAA, and actinomycin D. However, like tobacco tissues, sweet potato root isoperoxidases were distinctive in their distribution between cell wall and protoplast fractions as well as in their reaction to cut injury. The root isoperoxidases were also distinctive in their reaction to C2H4. This report deals mainly with age-, mechanical injury-, and C2H4-related changes in cell peroxidase of sweet potato leaves. MATERIALS AND METHODSHealthy storage roots of Ipomea batatas were purchased locally. Plants grown from several buds of single roots, with 2 to 3 or 7 to 8 shoots, were used in each experiment, especially in experiments in which leaf isoperoxidases were compared to the root isoenzymes.Mechanical injury was induced i...

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De Novo Synthesis of Peroxidase Isozymes in Sweet Potato Slices

Cited by 55 publications

References 25 publications

Peroxidase Activity in the Abscission Zone of Bean Leaves during Abscission

Peroxidase Activity in the Abscission Zone of Bean Leaves during Abscission

Ethylene-induced Phenylalanine Ammonia-Lyase Activity in Carrot Roots

Cell Isoperoxidases in Sweet Potato Plants in Relation to Mechanical Injury and Ethylene

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