Biochemical changes in pear (Pyrus communis L. depending on different phases of the dormancy

Pear cultivars of variable frost tolerance were tested as for frost injuries suffered as a consequence of artificial freezing temperatures during the endodormancy as well as the ecodormancy. Damages were registered according to a visually defined scale, then peroxidase and polyphenol-oxidase activity was checked in buds, spurs and limbs. According to our results, 'Packham's Triumph' was the most frost tolerant cultivar. Regarding enzyme activity of both enzymes, the performance of cultivars displaying different susceptibility was also different in spurs as well as in buds. Results referring to the endodormancy were especially instructive. During the ecodormancy, data obtained at the same time indicated the differences existing between the developmental stages of dormancy in the respective cultivars.

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Biochemical changes in pear (Pyrus communis L. depending on different phases of the dormancy

International Journal of Horticultural Science ◽

10.31421/ijhs/10/3/487 ◽

2004 ◽

Vol 10 (3) ◽

Author(s):

Göndör M. ◽

Honty K. ◽

Pedryc A. ◽

Hajdrik I. ◽

Stefanovits-Bányai É.

Keyword(s):

Enzyme Activity ◽

Polyphenol Oxidase ◽

Oxidase Activity ◽

Developmental Stages ◽

Frost Tolerance ◽

Biochemical Changes ◽

Polyphenol Oxidase Activity ◽

Pyrus Communis L ◽

Artificial Freezing ◽

Frost Injuries

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The effect of 1-MCP concentration on skin and flesh color polyphenol oxidase activity during cold storage and shelf life periods in ‘Ankara’ pear (Pyrus communis L.)

Acta Horticulturae ◽

10.17660/actahortic.2020.1275.31 ◽

2020 ◽

pp. 221-228

Author(s):

N. Bakoğlu ◽

N. Tuna Gunes

Keyword(s):

Shelf Life ◽

Polyphenol Oxidase ◽

Cold Storage ◽

Oxidase Activity ◽

Pyrus Communis ◽

Flesh Color ◽

Polyphenol Oxidase Activity ◽

Pyrus Communis L

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Enzyme activity in banana fruits rotted by Botryodiplodia theobromae Pat.

Acta Agrobotanica ◽

10.5586/aa.1978.004 ◽

2015 ◽

Vol 31 (1–2) ◽

pp. 41-46

Author(s):

Nityananda Chakraborty ◽

Balen Nandi

Keyword(s):

Enzyme Activity ◽

Polyphenol Oxidase ◽

Peroxidase Activity ◽

Oxidase Activity ◽

Botryodiplodia Theobromae ◽

Polyphenol Oxidase Activity

Peroxidase and polyphenol oxidase activities in fruits of two cultivars of banana, 'champa' and 'kanthali' rotted by <i>Botryodiplodia theobromae</i> Pat. was studied. The enzymes showed much higher activities in infected than that in uninfected 'tissues. Increase in peroxidase activity was evidently inhibited by cycloheximide. Polyphenol oxidase activity was also inhibited in presence of phenylthiourea and Na-diethyldithiocarbamate more strongly by the former. Increase in activities seemed to be due to increased sytheses of the enzymes. In an <i>in vitro</i> culture, the fungus exhibited some peroxidase but no polyphenoloxidase activity.

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Plant age affects elicitation of polyphenol oxidase activity by neem extract in Solanum lycopersicum against Pseudomonas syringae pv. tomato

Israel Journal of Plant Sciences ◽

10.1080/07929978.2015.1035606 ◽

2015 ◽

Vol 62 (4) ◽

pp. 283-293 ◽

Cited By ~ 1

Author(s):

Navodit Goel ◽

Prabir Kumar Paul

Keyword(s):

Enzyme Activity ◽

Pseudomonas Syringae ◽

Polyphenol Oxidase ◽

Azadirachta Indica ◽

Oxidase Activity ◽

Plant Age ◽

Polyphenol Oxidase Activity ◽

Neem Extract ◽

Defense Enzyme ◽

The Impact

Polyphenol oxidase (PPO) is a key defense enzyme widely distributed in the plant kingdom. The enzyme has been reported to be inducible by biotic inducers. The present study instigated the impact of plant age on induction of activity of PPO and pattern of isoenzymes by aqueous fruit extracts of Azadirachta indica (neem). The study involved the host–pathogen system of tomato (F1 tomato, Roopsi variety, Century seeds) and Pseudomonas syringae pv. tomato. Plants of 6, 8, 10 and 12 weeks of age were used for the study. Samples were collected 0, 24, 48, 72, 96 hours and 2 weeks post treatment. The results demonstrated that plant age impacts the expression and inducibility of PPO in tomato. Neem extract does not significantly inhibit the growth of Pseudomonas syringae pv. tomato. Therefore, the reduction in disease severity in neem-treated plants is related to changes in the activity of PPO in the host plant. The 10-week-old plants had significantly highest PPO activity as compared to 12-week-old plants, which had the lowest enzyme activity. Consequently, the 10-week-old plants were more resistant to the pathogen among all the ages studied. The distal untreated leaves or the leaves emerging after neem treatment were also significantly resistant to the pathogen. Treatment with neem prior to pathogen inoculation was more effective in priming the plants. The neem extract induced the defense response in tomato primarily through upregulation of the PPO gene.

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Some Kinetic Properties of Polyphenol Oxidase Obtained from Various Salvia Species (Salvia Viridis L., Salvia Virgata Jacq. and Salvia Tomentosa Miller)

Food Science and Technology International ◽

10.1177/108201303036476 ◽

2003 ◽

Vol 9 (4) ◽

pp. 309-315 ◽

Cited By ~ 11

Author(s):

G. Gundo[notdef]ggmaz ◽

S. Do[notdef]ggan ◽

O. Arslan

Keyword(s):

Ascorbic Acid ◽

Enzyme Activity ◽

Polyphenol Oxidase ◽

Oxidase Activity ◽

Arrhenius Equation ◽

Activation Energies ◽

Kinetic Properties ◽

Acid Activation ◽

Effective Inhibitor ◽

Polyphenol Oxidase Activity

Polyphenol oxidase (PPO) was partially purified by (NH4)2SO4 precipitation followed by dialysis from different organs of Salvia species (Salvia virgata Jacq., Salvia viridis L. and Salvia tomentosa Miller). Polyphenol oxidase activity was measured spectrophotometrically at 420 nm using catechol as a substrate. Vmax, KM and Vmax/KM values for polyphenol oxidase activity from different organs of Salvia species were determined. S. tomentosa Miller was the species with the highest PPO activity, followed by S. virgata Jacq and S. viridis L. S. tomentosa Miller was the most suitable Salvia species for dark-tea preparations because of the highest Vmax/KM values. The effects of various inhibitors on the reaction catalysed by the enzyme were tested and calculated I50 values, reduced the enzyme activity by 50%. The most effective inhibitor was L-cysteine followed by ascorbic acid. Activation energies, Ea, were determined from Arrhenius equation.

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