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The beet cyst nematode (BCN) (Heterodera schachtii), and beet curly top virus-severe (BCTV-Svr) (Curtovirus betae) are two important pathogens of sugar beet fields worldwide. Therefore, the reaction of 14 genotypes was separately assessed, using Jolgeh and Sanetta cultivars as susceptible and resistant controls, respectively, in completely randomized design experiments for BCN and BCTV-Svr. Reactions were based on the cyst and egg counts and symptoms severity index. Experiments were performed in the greenhouse of Tarbiat Modares University, Tehran, Iran, and were repeated twice independently. Based on the results of initial experiments, the S1-960090, S1-940324, S1-960294, and S1-960284 genotypes resistant to the BCN were selected for further investigation. Furthermore, the reaction of the four selected genotypes to BCN, BCTV-Svr, and the combination (mixture) of the two pathogens was evaluated by analyzing their growth, physiological, and biochemical characteristics, and virus accumulation. Resistant genotypes showed higher levels of defense-related enzymes such as catalase, guaiacol peroxidase, and polyphenol oxidase, whereas susceptible genotypes exhibited significant reductions in photosynthesis, greenness, and chlorophyll a, b, and carotenoid content compared to non-inoculated and resistant plants. This is the first study conducted to search for dual-resistance sources against two devastating pathogens that frequently occur in the sugar beet-growing regions of Iran. Based on the results of this experiment, genotypes S1-960090 and S1-940324 were identified as resistant to both pathogens and are recommended for breeding purposes.
 

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The biocontrol activity of two isolates of Candida membranifaciens against grey mold of apple fruit caused by Botrytis mali and their ability to induce biochemical defense responses in apple tissue were investigated. Apple fruit (Malus domestica) wounds were inoculated with 50 µl yeast suspension (1 × 10⁷ CFU/ml) of C. membranifaciens followed 4 h later by 20 µl of conidial suspension of B. mali (1 × 10⁵ conidia/ml). The apples were then incubated at 20 ºC for 8 days. Lesion diameter sizes were measured 4 and 8 days after pathogen inoculation. In addition to controlling grey mold, these two isolates of C. membranifaciens caused increases in peroxidase and β-1, 3-glucanase activities. These isolates also caused inhibition in catalase activity. The accumulation of phenolic compounds was increased in apple fruit treated with antagonists and inoculated with B. mali and reached its highest level 6 days after treatment. The ability of C. membranifaciens to affect H2O2-metobolizing enzymes and increase levels of β-1, 3-glucanase activity and phenolic compounds may be some of mechanisms responsible for its biocontrol activity.  

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The aims of this study were to assess the effects of drought stress on peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT) activities as well as free proline content and growth parameters of Pistacia khinjuk seedlings under drought stress. Therefore, the one-year seedlings of Pistacia khinjuk subjected to water stress (25%, 50%, 75%, and 100% field capacity) for 8 months in greenhouse condition. Results showed that drought stress decreased height, collar diameter, shoot dry weight and root dry weight of P. khinjuk seedlings. But it had different effects onantioxidant enzyme activities in root and shoot of P. khinjuk seedlings. Drought stress increased CAT activity in shoot and root of seedlings and its activity was higher in 25% field capacity (FC) than other treatments. Also, the POD enzyme activity increased in root and shoot of seedlings subjected to drought stress. The SOD activity was at the lowest level in 100% FC than other treatments. The results also showed that free proline accumulation was lower in well watered seedlings and increased under drought stress.

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To investigate the effect of droughtstress on chlorophyll content, enzymatic responses and some growth characteristics of Acacia victoriae seedlings and the effect of super-absorbent polymers (SAP) in reducing drought stress, a split plot experiment based on the completely randomized design was conducted. The treatments included four levels of drought stress (15, 30, 60 and 100% of field capacity) and four levels of SAP (0, 0.2, 0.4 and 0.6% weight percentages). The results of ANOVA showed a significant effect of drought stress on all growth characters, chlorophyll content and catalase and peroxidase enzymes activity, while the SAP didn't show any significant effect on the weight and areas of the leaves. The interaction effect between drought stress and SAP on the weight, number of leaves, proportion of root dry weight to aerial organs, chlorophyll and peroxidase enzyme activity was also significant. The effect of drought stress on reducing the number of the leaves, leaf area, length, volume and surface of roots and also increasing the root dry weight to aerial organs dry weight ratio, amount of chlorophyll and activity of antioxidant enzymes was significant. The different levels of SAP could absorb and hold water and consequently reduce the effect of drought stress and improve the growth characteristics and reduce the activity of catalase and peroxidase enzymes.

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The effect of salicylic acid (SA) on induction of resistance against root-knot nematode (Meloidogyne javanica) and the effect of M. javanica to induce biochemical defense responses in tomato (Solanum lycopersicum L.) roots at six-leaf stage were investigated. Meanwhile, the effect of different concentrations of SA on mortality of second stage juveniles of M. javanica was examined. Changes in the activity of cytoplasmic peroxidase (POX), catalase (CAT) and phenylalanine ammonia lyase (PAL) enzymes in the roots of tomato seedlings were measured during seven successive days after inoculation with M. javanica in greenhouse. SA was used as soil drench and leaf spray. The efficiency of treatments were evaluated by measuring diameter of galls, number of galls per plant, number of egg masses per plant, number of eggs per individual egg mass, root and foliage fresh weights. The results showed that use of SA as soil drench and leaf spray significantly reduce diameter of galls 28% and 32%, number of galls per plant 40% and 44%, number of egg masses per plant 45% and 49% and number of eggs per individual egg mass 53% and 55% compared to control (inoculated with nematode only). The activity of the enzymes (POX, CAT and PAL) increased in comparison with plants treated with distilled water. The maximum level of larva mortality was observed at 7 mM SA with no significant difference at concentration of 6 mM. SA caused 21.2% mortality of larvae at concentration of 5 mM.    

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DNA molecules contain nitrogenous bases that look like fluorophores; however they are weakly or non-fluorescent. Hence, it is important to identify DNA binding-ligands that do not show fluorescence emission in the Free State, though their fluorescence intensity increases upon binding to DNA. Here, we report metal ions (either K and Na) induced guanine quadruplex formation with PS2.M, d (GTG3TAG3CG3T2G2), which shows peroxidase function when complexed with hemin. Ultravioletvisible absorption spectroscopy revealed activity of the PS2.M oligomer as DNAzyme, and Circular Dichroism spectroscopy showed the formation of G-quadruplex structure of PS2.M. We also studied the intrinsic fluorescence of G-quadruplex forming peroxidase-like DNAzyme. The fluorescence spectra showed increment in the intrinsic fluorescence of folded DNA in comparison with its unfolded structure of the same sequence. Moreover, unsymmetrical cyanine dye (SYBR gold) was utilized as a probe for the study of the extrinsic fluorescence of G-quadruplex DNA, where it could discriminate between the single and four-stranded structures of DNA. Also the G-quadruplex dye interaction was also investigated using Circular Dichroism and Fluorescence spectroscopies.

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The effects of salicylic acid (SA) nano-formulation on expression of peroxidase (113-114) genes and peroxidase and phenylalanine ammonia lyase (PAL) were investigated in wheat cultivar (Bezostaya) susceptible to Heterodera filipjevi. The wheat roots and leaves were randomly divided into control group and groups exposed to 62.5, 125 and 250μg/ml SA. A spectrophotometric analysis was carried out using root extracts from infected plants at 4, 7 and 11days post inoculation with nematode (DAI) for peroxidase and PAL. The expression of peroxidase (113-114) genes was evaluated by Real time PCR analysis. Peroxidase activity was significantly increased in treatments exposed to 250µg/ml of nanosalicylic acid at 11 DAI. Phenylalanine ammonia lyase activity was induced in the treatments exposed to 250 and 125µg/ml nanosalicylic acid compared to the control at 4 and 7 DAI, respectively. Phenylalanine ammonia lyase activity was also increased in the treatments exposed to 62.5 and 250µg/ml of nanosalicylic acid compared to the control at 7 DAI. The expression level of peroxidase 113-114 in wheat leaves was significantly raised at 4 DAI when 62.5µg/ml of nanosalicylic acid was used. There was also a significant difference between expression levels of peroxidase 113-114 genes at applications of 125 and 250µg/ml of SA in comparison with the control at 4 and 7 DAI, a significant decrease was revealed in the gene expression in treatments exposed to 62.5, 125 and 250µg/ml of nanosalicylic acid compared to the control at 11 DAI. It was concluded that higher concentrations of nanosalicylic acid have a potential effect on peroxidase and PAL activities in wheat infected by H. filipjevi. High concentration of nanosalicylic acid has inhibitory effects on the expression level of peroxidase gene.

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The quest for new sources of cheap and eco-friendly insecticide for insect pest management remains a major challenge facing cowpea farmers in many developing countries. In this study, the toxicity and biochemical mechanisms associated with the insecticidal efficacy of acetone and n-hexane extracts of Xylopia aethiopica (Dunal) and Senna occidentalis (L.) on Callosobruchus chinensis (L.) were investigated. The insecticidal efficacy varied with concentration, exposure time and extracts type. Acetone extract of X. aethiopica was less toxic (LD₅₀ = 2.47%) than its n-hexane extract (LD₅₀ = 1.39%) but with S. occidentalis, acetone extract was more toxic (LD₅₀ = 0.73%) than n-hexane extract (LD₅₀ = 1.37%). Acetone extract of both plants evoked a significant reduction in egg-laying and eclosion ability of adult C. chinensis compared to n-hexane extract except on cowpea pre-treated with acetone extract of S. occidentalis. Only the extracts of X. aethiopica reduced protein concentration compared to control. The activity of glutathione reductase and glutathione peroxidase was significantly reduced by both extracts of S. occidentalis while only n-hexane extract of S. occidentalis elicited a significant reduction in the activity of glutathione S-transferase and trehalase compared to other treatment levels. GC-MS analysis depicted Diisoocotyl phthalate (50.37%) and isomers of Aromandendrene (19.22%) as the main compounds in S. occidentalis and X. aethiopica respectively. Both botanical extracts also contained other insecticidal and insectifuge compounds in differential amounts. Overall, the findings demonstrated the potential of both botanical extracts, particularly acetone extract of S. occidentalis as alternatives to synthetic insecticide for controlling adult C. chinensis.
 

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Aims: Peroxidases are used in a wide range of biotechnological processes, most of which are carried out at high temperatures and high pH levels. Since most of the commonly used peroxidases are unstable and inactive in alkaline conditions and high temprature, it is necessary to find thermoalkalophilic peroxidases for practical purposes.
Materials and Methods: In this study, extracellular production of peroxidase in the native strain Bacillus tequilensis was studied. for this purpose, Enzyme activity was evaluated using two substrates 2,4-DCP and pyrogallol in bacterial liquid culture and the effect of culture time on enzyme production, as well as the effect of parameters such as pH and temperature on enzyme activity investigated. The relative purification of the enzyme was performed using ion exchange chromatography with sephadex DEAE A50 and the kinetic parameters of enzyme activity were evaluated. In this study, kinetic parameters such as Km and Vmax were calculated.
Results: Measurement of enzyme activity at different times of culture indicated that the highest amount of peroxidase production was obtained 72 h after bacterial culture.

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Reactive oxygen species (ROS) at low concentrations effectively regulates intracellular pathways such as gene expression. Whereas their high concentrations are involved in the pathogenesis of many diseases by causing oxidative stress and damaging vital macromolecules. Each cell is equipped with an antioxidant defense system to neutralize high levels of ROS. Peroxidase, as an essential antioxidant enzyme, catalyzes the oxidation of various substrates using hydrogen peroxide which is a reactive oxygen species. Since, the caffeine and theobromine are widely consumed daily in the world, and their concentrations affect the activity of many enzymes. Therefore, in the present study, the inhibitory effect of these methylxanthines on peroxidase activity has been examined. The peroxidase activity is measured by a spectrophotometer at 510 nm for 3 minutes with following absorption due to the oxidation of 4-aminoantipyrine in the presence and absence of caffeine and theobromine. In this study, it was observed that both compounds had an inhibitory effect on peroxidase activity. The values of IC₅₀ for theobromine and caffeine were obtained as 0.5 and 0.6 mmol, respectively. Moreover, the values of K_m and V_max showed that both inhibitors acted by an un-competitive mechanism of inhibition. Also, K_i values for theobromine and caffeine were calculated 0.03 and 0.08 mM, respectively. The values of K_i and IC₅₀ for theobromine was lower than those of caffeine indicating that theobromine has a higher inhibition strength and binding affinity to the enzyme-substrate complex. Therefore, it can be concluded that theobromine has a stronger inhibitory effect on peroxidase activity.

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Grape trunk diseases are critical problems for grapes from the time of planting to the harvest stage. Grapes are susceptible to 29 fungal diseases due to their perennial woody trunk, so identifying and managing them is crucial. Among the methods of controlling these diseases, feeding with mineral fertilizers to reduce leaf symptoms resulting from the toxic secretions of fungi living in the woody part of the tree is of great importance. To manage these diseases, a mixture of fertilizers including calcium chloride CaCl₂, 466 g, magnesium nitrate Mg(NO₃)₂, 403 g, seaweed extract (75 ml) and sterile distilled water 466 ml per liter of foliar spraying on the selected treatments in Sohrabi’s garden were used once every 20 days. Guaiacol peroxidase, catalase and leaf area index were measured in Sohrabi’s garden during 2017 and 2018 and were compared with the control. In the treatments sprayed with the fertilizers, the average amount of guaiacol peroxidase enzyme was 12.72 µl compared to the control (10.6 µl) and the average amount of catalase enzyme was 83.68 µl compared to the control (31.85 µl). The average size of the leaf area in the foliar treatments in Sohrabi’s garden was 11564 mm², compared to the control that was 4959 mm². The severity of the disease in the sprayed treatments (19.95 %) was lower than the control (56.6 %). These results are due to the increase in the leaf surface, which increases the amount of photosynthesis, and the increase in guaiacol peroxidase and catalase, which reduce the oxidative stress resulting from fungal secretions, which resulted in decreasing symptoms in foliar treatments.

 

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Wheat Streak Mosaic Virus (WSMV) causes extensive economic damage to wheat (Triticum aestivum L.) in many regions of the world. The present study was conducted to find out if the variations in biochemical changes in reaction to WSMV infection in F2 generation of either potentially resistant (Adl-Cross) or susceptible (Marvdasht) cultivars are genetically inherited. A factorial experiment was employed with two factors of: genotypes (Adl-Cross, Marvdasht, reistant F2s and susceptible F2s), and inoculation (either infected or non infected) at Shiraz University, Iran during 2007-2009. Leaves of seedlings were harvested at different time intervals for total protein, total phenolic compounds and peroxidase activity analysis. Results indicated that virus infection caused stress in all genotypes. Total protein reduction in the inoculated resistant Adl-Cross and in its F2s was not significant whereas it was significant in the inoculated susceptible Marvdasht and its susceptible F2s. Viral infection reduced peroxidase activity in the susceptible Marvdasht cultivar and in its susceptible F2s whereas in Adl-Cross and in its resistant F2s the activity was increased. It is speculated that peroxidase enzyme may affect synthesis of compounds effective in resistance to wheat streak mosaic virus. The trend in the increase in phenolic compounds indicated that their formation and accumulation is faster in the resistant genotypes as compared with the susceptible ones. It appears that the extent of total protein, total phenolic compounds as well as peroxidase activity changes in response to WSMV are inherited by the next generations and these biochemical changes in a genotype could be adopted as selective factors in the preliminary experimental stages of selection for tolerance to the virus.

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Objective: Environmental pollution is of major concern today and lead is considered to be one of the most important environmental pollutants. Long-term contact with lead causes harmful effects to humans. This study seeks to determine the effects of Curcuma longa (turmeric extract) consumption and exercise training on glutathione peroxidase and protein carbonyl in kidney and spleen tissues from rats exposed to lead. Methods: We randomly classified 60 male rats into the following six groups of 10 rats per group: 1) control; 2) sham (turmeric extract solvent); 3) lead; 4) training + lead; 5) turmeric extract + lead; and 6) training + lead + turmeric extract. The training program for groups 3 and 6 consisted of running on a level treadmill for 40 sessions (eight weeks at five sessions per week) at a speed of 22 to 15 m/min for 26 to 64 minutes. Turmeric extract (30 mg/kg) was injected three times per week for eight weeks. Amounts of glutathione peroxidase and protein carbonyl were measured by ELISA. Results: The amount of protein carbonyl in the kidney and spleen tissues of the lead group increased compared to the sham, training, combined and extract groups. Rats in the combined, extract and practice groups (F=4.787; P=0.002) had lower levels of protein carbonyl in their kidney and spleen tissues compared to the sham group (F=6.970, P=0.000). Glutathione peroxidase levels in the kidney and spleen tissues were less in the lead group compared to the sham group. However these levels in the training, extract, and combined groups increased compared with the sham group (respectively, in kidney and spleen P=0.051, F=2.466 and P=0/086, F=2.11). Conclusion: Intake of turmeric extract and exercise alone did not cause complete inhibition of the oxidative effects in kidney and spleen tissues. However, exercise and consumption of turmeric extract can be effective in reducing the harmful effects of lead.

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A greenhouse experiment was conducted to investigate the effects of mycorrhial fungus (Glomus mosseae) on cadmium (Cd) toxicity in pepper (Capsicum annuum L. cv. Zhongjiao 105) plants. Half of plants were inoculated with arbuscular mycorrhizal fungi (AMF). Cd was supplied in the form of cadmium chloride at 0.0, 0.1 and 0.5 mM through irrigation water in the soil. Mycorrhizal colonization was higher in the control than in cadmium-treated soil. Dry weights of root and shoot of mycorrhizal (M) plants were higher than non mycorrhizal (NM) ones in both control and cadmium treatments. Measurements of Cd concentration indicated that M plants immobilized more Cd in the root and partitioned less Cd to the shoots. Cd decreased the leaf chlorophyll content, total sugar and total protein contents, and the concentrations of phosphorous and magnesium. M plants had greater contents of chlorophyll, total sugar, total protein and P and Mg concentrations than NM plants. Moreover, increasing the Cd concentration caused an increase in malondialdehyde (MDA) content in leaves of pepper plants; however, M plants showed a lower MDA content than NM plants. Cd decreased the activity of superoxide dismutase (SOD) in leaves of NM and M plants, on the other hand, it increased the activity of peroxidase (POD) and ascorbate peroxidase (APX) in leaves of NM and M plants. APX was stimulated more than POD in M plants versus NM plants, suggesting that APX is a major player in H₂O₂-scavenging in M plants. The study suggests that mycorrhization with G. mosseae can be a suitable way to induce Cd-stress resistance in pepper plants.

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Enzymes in plant tissues can have undesirable or desirable effects on the quality of fruits and vegetables; therefore management of their change in fruits and vegetables is one of the concerns in food industry. Nowadays consumer's trend has been oriented to use fresh products or foods prepared by little process, therefore producers are interested the ways to increase shelf life by alternative methods. The aim of this work was to study the ability of thyme (Thymus vulgaris L.) essential oil in reduction of peroxidase enzyme activity (as an important biochemical degradation factor) in the black Spanish radish and green bean. For this purpose, plant extract containing peroxidase enzyme was mixed with a substrate mixture composed from guaiacol, hydrogen peroxide, sodium phosphate buffer and different concentrations of thyme essential oil (50, 75, 100 and 200 μg/100 ml). The absorbance of the samples was measured at 470 nm for 400 seconds spectrophotometrically. Results of this study showed that the peroxidase enzyme activity in the black Spanish radish and green beans were 4625 and 51 (gram of vegetable × second / unit of activity) respectively and by addition of thyme essential oil in the above concentrations the peroxidase enzyme activity of black Spanish radish was 2655, 2550, 2015 and 2162 (gram of vegetable × second / unit of activity) respectively and the peroxidase enzyme activity of green bean was 708, 6/551, 579 and 690 (gram of vegetable × second / unit of activity) respectively.

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Selenium is an essential element for humans, therefore, adding it to plants is convenient for biofortification. Thus, the aim of this work was to analyze experimentally the ability of sodium selenite to increase the concentration of Se and modify the antioxidant activity in tomato plants. We used plants of the Toro hybrid variety and applied three treatments: 0, 2 and 5 mg L^-1 of selenium as sodium selenite (Na₂SeO₃) using an irrigation system. Three samplings 40, 80, and 120 days after transplantation and a quantification of the accumulation of selenium and macronutrients in leaves, stems, and fruits were carried out. Plant height, stem diameter, firmness, and total solids of fruits and total dry matter were measured. The enzyme activity of catalase, glutathione peroxidase, and superoxide dismutase was quantified. The results indicated positive effects of Se on agronomic variables of the plants and fruit quality; however, fruit production showed no significant differences. Se had no effect on the concentration of the macro and micronutrients. The addition of 5 mg L^-1 of Se resulted in significant increases in the concentration of selenium on a dry basis, reaching 20.4 µg g^-1 in leaves, 52.3 µg g^-1 in stems, and 35.8 µg g^-1 in fruits. The increase in enzyme activity in the fruits was enhanced by the application of 5 mg L^-1 of Se: There was up to 352.7% more catalase activity, 312.2% more glutathione peroxidase activity, and 200.8% more superoxide dismutase activity compared with the control.

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In this study, the crude protein extract containing PolyPhenolOxidase (PPO) and Peroxidases (POD) were extracted from medlar fruit (Mespilus germanica L.) grown in Golestan Province, Iran. POD and PPO activities were studied using guaiacol and catechol as substrates, respectively. The effect of pH, temperature and thermal stability, inhibitors and cations were investigated. Results showed that V_max was higher for PPO compared to the POD. The optimum pHs for POD and PPO were obtained at 6.5 and 5.5, respectively. The optimum temperature for both enzymes was 35°C. The Iranian medlar POD was more thermal stable than the PPO. Ascorbic acid had the highest inhibitory effect on both enzymes. Ca²⁺ and Zn²⁺ had the highest decreasing and increasing effect on both enzymes.

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Fruits and vegetables are perishable products due to their high water content and high enzymatic activity, and large amounts of them are deteriorated each year before consumption. Different methods such as the use of heat or chemical preservatives are common to reduce food waste, but increasing consumer demand for fresh or minimal processed foods has led to increased research for finding alternative preservation methods. In this study, the ability of clove, cumin and fennel essential oils (concentrations of 50, 75, 100 and 200 ppm) in reducing peroxidase enzyme activity (as one of the main factors of biochemical deterioration) in apple fruit was investigated. Clove essential oil in pure state and in concentrations of 100 and 75 ppm reduced 66.67% of the peroxidase enzyme activity while concentrations of 200 and 50 ppm of clove essential oil reduced 62.97 and 48.15% of the peroxidase enzyme activity in apple fruit respectively. Cumin essential oil in all applied concentrations led to a 66.67% reduction in peroxidase enzyme activity in apple fruit samples. Also, the use of concentrations of 100, 75 and 50 ppm of fennel essential oil has reduced 62.97% of peroxidase enzyme activity in apple fruit samples, while increasing the fennel essential oil concentration reduces its inhibitory effect on peroxidase enzyme activity so that the application of pure state and concentration of 200 ppm of fennel essential oil reduced 18.52 and 55.56% of peroxidase enzyme activity in apple fruit, respectively. The results of response surface optimization method showed that the lowest peroxidase enzyme activity for clove, cumin and fennel essential oils were obtained in essential oil concentration and enzyme activity time of 200 ppm and 40 seconds for clove essential oil, 146 ppm and 112 seconds for cumin and 130 ppm and 183 seconds for fennel essential oil respectively.