Polyphenol Oxidase Enzyme Activity Research Articles

Potatoes (Solanum tuberosum L.) grown at “Patata dell'alto Viterbese” PGI have different quality characteristics and storage responses

Four pre-selected potato cultivars (Solanum tuberosum L.) from the “Patata dell’Alto Viterbese” PGI area underwent physico-chemical and enzymatic characterization to assess their suitability for specific processing line. Key chemical parameters (reducing sugar content (RSC), total phenol content (TPC), dry matter (DM), physical attributes (firmness), physico-chemical aspects (color, browning development), and enzymatic factors (polyphenol oxidase enzyme activity, PPO) were analyzed at harvest and monthly during a 6-month storage period over two production seasons (2020 and 2021). The results of one-way within-subject ANOVA and Principal Component Analysis (PCA) highlighted the superior attributes of the ‘Fontane’ cultivar for the processing industry, particularly for frying applications (e.g., chips, French fries, etc.). In comparison to other tested cultivars, ‘Fontane’ exhibited: i) the highest DM (> 200 g kg−1), ii) the lowest TPC and RSC, iii) the greatest firmness, iv) low susceptibility to browning, and v) high tolerance to Low-Temperature Sweetening (LTS). The ‘Jelly’ cultivar displayed favorable attributes for versatile use, suitable for both fresh market uses (roasting, homemade “gnocchi”, etc.) and industrial applications (fresh-cut or dried potato). It demonstrated high DM content (200 g kg−1) and firmness, the lowest PPO activity, good TPC, but higher RSC than ‘Fontane’. However, elevated RSC for ‘Jelly’ renders it less suitable for industrial frying. ‘Constance’ and ‘Gaudi’ exhibited positive traits for fresh market use such as boiling and steaming, with moderate to low DM content and firmness. Nonetheless, both cultivars displayed low tolerance to LTS, and ‘Gaudi’ exhibited the poorest processing properties, showing the highest susceptibility to browning.

Automatic non-destructive estimation of polyphenol oxidase and peroxidase enzyme activity levels in three bell pepper varieties by Vis/NIR spectroscopy imaging data based on machine learning methods

The browning process of food products if often formed upon cutting and damage during their processing, transport, and storage, amongst other potential sources and reasons. Enzymic browning can be mainly due to polyphenol peroxidase (PPO) and peroxidase (POD) enzymes. Visible/near-infrared (Vis/NIR) imaging spectroscopy in the range of 350-1150 nm was used in this study for automatic and non-destructive evaluation of PPO and POD activity levels in three bell pepper varieties (red, yellow, orange; N=30), with a total of 30 inputs samples in each variety. The spectral data were then modeled by the partial least square regression (PLSR) throughout the whole spectral range, without using any subset of the most effective wavelength (EW) values. Regression determination coefficient (R2) values for the estimation (prediction) of POD enzyme activity levels were 0.794, 0.772, and 0.726 for red, yellow, and orange bell peppers, respectively, all over the validation set. At the same time, the activity levels of PPO enzyme over bell peppers showed R2 values of 0.901, 0.810, and 0.859, for red, yellow, and orange bell peppers, respectively, all over the validation set. In addition, a combination of Support vector machine (SVM) with either genetic algorithms (GA), particle swarm optimization (PSO), ant colony optimization (ACO), or imperialistic competitive algorithms (ICA) hybrid machine learning (ML) techniques were used to select the optimal (discriminant) spectral EW wavelength values, and regression performance was consistently improved, to judge from higher regression fit R2 values. Either 14 or 15 EWs were computed and selected in order of their discriminative power using previously mentioned ML techniques. The SVM-PSO method resulted the best one in the process of selecting the most effective wavelength values (nm). On the other hand, three regression methods comprising PLSR, multiple least regression (MLR), and neural network (NN), were employed to model the SVM-PSO selected EWs. The ratio of performance to deviation (RPD), the R2 and the root mean square error (RMSE), over the test set, for the non-linear NN regression method exhibited better results as compared to the other two regression methods, being closely followed by PLSR, and therefore NN regression method was selected as the best approach for modeling the most effective spectral wavelength values in this study.

The effect of cold plasma treatment on quality attributes and shelf life of apples

The effectiveness of atmospheric air dielectric barrier discharge (DBD) cold plasma was compared with existing decontamination methods for improving the quality and shelf life of apples. The samples were stored in two different storage conditions (ambient, 27 ± 3 °C; and cold, 10 ± 1 °C) to check the effect of storage temperature on their shelf life. The microbial load on the apples was reduced after all the treatments, and samples stored at 10 ℃ showed a higher reduction in microbial load with increased shelf life. The polyphenol oxidase (PPO) and phenylalanine ammonia-lyase (PAL) enzyme activities showed a significant reduction after cold plasma treatment; however, peroxidase (POD) activity showed a lower reduction than PPO and PAL enzymes. Color changes evaluated using L*, a*, and b* values showed higher retention for the red color in the treated samples compared to control samples, and the firmness of all treated samples was maintained throughout the storage period. The total phenolic content (TPC) increased after cold plasma treatment and carotenoid content was retained in the treated samples. In addition, the present study demonstrated that the novel cold plasma decontamination method was more effective in reducing the pesticides (Malathion, Fenthion, and Chlorpyrifos) from the apple surfaces than the conventional methods. Cold plasma can be a better alternative for decontaminating apples; however, other hurdles may be required to increase their shelf life further.

Efficacy of Using Chemical Inducers and Biological Agents to Control Strawberry Leaf Spot Disease on Chemical Components and Enzyme Activity

Strawberry plants are subjected to many pathogens. Fungal diseases of strawberries are important worldwide and occur in all parts of the plant, including leaves, crowns, and fruits. The results of the bio-agent experiment indicated that Trichoderma harzianum was the most effective in reducing the growth of Alternaria alternata and Botrytis cinerea in vitro, the main causes of leaf spots in strawberry plants. The inhibition zone was observed and mycelium of T. harzianum invaded the colony of the tested pathogens. The importance of the biochemical study of defense reaction in the physiology of disease resistance was accepted. The activity of total, free, and conjugated phenols as well as peroxidase, polyphenol oxidase, and catalase enzyme activities were determined in resistant and susceptible strawberry cultivars. All the total, free, and conjugated phenols increased in resistant cultivars (Fortuna and Winter Star) and decreased in susceptible cultivar (Festival). Oxidative enzymes, like the increased activity of enzymes that appear mince of new polypeptide protein, have become models in the study of plant disease resistance. The higher content of peroxidase, polyphenol oxidase, and catalase enzymes in resistant cultivars, were noticed compared with those in susceptible ones. It was found also that, the chemical inducers increased total phenols in resistant and susceptible cultivars i.e., potassium di-phosphate, ferrous sulphate, and oxalic acid. Inducer resistance also caused an increase of free phenols than the control. However, conjugated phenols accumulated faster after using chemical inducers in the leaves of the resistant cultivars, than the susceptible ones.

Melatonin postharvest spray influence on white mulberry browning, storage life, and biochemical changes

White mulberry (Morus alba L.) fruit is a rich source of bioactive compounds, but it is highly perishable and vulnerable to browning. In the current study, melatonin at concentrations of 0, 125, 250, 500, and 1000 µM was sprayed on mulberry fruit and stored at 1 °C for 12 d. Melatonin treatment yielded the lowest browning index during storage time. This reduction was accompanied by a significant decrease in malondialdehyde, H2O2 and polyphenol oxidase enzyme activity. The results showed that melatonin reduced weight loss and maintained pH, as well as total soluble solids. Furthermore, the total phenol, total flavonoids and ascorbic acid contents in treated fruit were significantly higher than in an untreated fruit, which was accompanied by an increase in antioxidant capacity. With assuming 40 % browning would render the fruit unmarketable, melatonin treatments could extend mulberry storage life beyond 8 days. The 500 and 1000 μM melatonin treatments showed the most effective results. In conclusion, exogenous melatonin application can be considered a safe and promising procedure to maintain the quality of mulberry fruit during low-temperature storage.

Defense related enzymes implicated in resistance and susceptibility to Rhizoctonia solani, the causal agent of sheath blight of rice

Plants have evolved various defense mechanisms to defend themselves from phytopathogens. Pathogenesis-related proteins are produced as part of the active defenses. In this work, changes in the activity of defense-related enzymes in rice in response to Rhizoctonia solani were examined at different time intervals viz., 0, 24, 48, and 72 h post inoculation (hpi), in late tillering tolerant and susceptible cultivars of rice. When the pathogen was induced, the activities of defense-related enzymes like chitinase, b-1,3-glucanase, peroxidase (PO), polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL), and total phenol content significantly increased in the tolerant cultivar (Tetep) compared to susceptible (KRH-4). Tetep showed increased chitinase activity up to 72 hpi, whereas KRH-4 showed no significant change up to 48 hpi but then increased activity at that time. When compared to the susceptible cultivar, tolerant Tetep had the maximum b-1-3 glucanase activity at 48 hpi. Tetep had an early induction of PAL with the highest activity at 24 hours compared to the control, but no proper trend was seen in susceptible cultivar. The early PO activity culminates in Tetep at 48 hpi. Tetep and KRH-4 both showed higher PPO enzyme activity at 48 hpi. In both the tolerant and susceptible cultivars, SOD activity steadily rose to 24 hpi and subsequently increased gradually up to 72 hpi. Tetep reported a higher total phenol concentration in the infected sheath samples than KRH-4 at 72 hpi. In this work, we looked at the biochemical methods for describing the defense-related enzymes against the sheath blight pathogen.

Evaluating the effects of chitosan incorporated with seabuckthorn leaf extract composite edible coatings on the shelf life of peach (Prunus persica L.) fruits

Peaches are highly nutritious and delicious fruits with a limited shelf life. The present study was aimed to test the efficiency of chitosan (CHI) coatings incorporated with seabuckthorn leaf extract (ST) in extending the shelf life of peach fruits at refrigerated temperature. Peach fruits of ‘Elberta’ cultivar were coated with one of the following treatment combinations: distilled water (control), CHI (1.0%), CHI (1%) + ST (0.5%), CHI (1%) + ST (1.0%), CHI (1%) + ST (1.5%) and CHI (1%) + ST (2.0%) and then stored at 4 °C for 25 days. The combined treatment of CHI and ST showed a synergistic effect in significantly decreasing the skin browning and maintaining the firmness during the storage period, corroborated by the decline in the polyphenol oxidase, cellulase and pectinase enzyme activity. In particular, fruits treated with CHI (1%) + ST (1.5%) and CHI (1%) + ST (2.0%) showed maximum efficiency in retaining the physico-chemical attributes, increasing the antioxidant potential and controlling the browning during post harvest period upto 25 days under refrigerated temperature at 4 °C. Furthermore, besides maintaining the quality parameters, the treated fruits showed a significant reduction in microbial spoilage and maintaining the acceptable sensory attributes. Therefore, the study employing the incorporation of Seabuckthorn leaf extract into chitosan edible coating could be a valuable addition and promising approach to different existing preservation techniques towards extending the shelf life of peach fruits.

Investigation of inhibition kinetics of various plant extracts on polyphenol oxidase enzyme from Paulownia Tomentosa and binding mechanism by molecular docking

Polyphenol oxidase/tyrosinase enzyme, which contains binuclear copper clusters play an important role in melanogenesis and enzymatic browning. Therefore, its inhibitors can be attractive in cosmetics and medicinal industries as depigmentation agents and also in food and agriculture industries as antibrowning compounds. Our aim in this study is to find natural plant extracts that will inhibit the polyphenol oxidase enzyme. The inhibitory effects of Verbascum thapsus, Tanacetum vulgare, Solanum nigrum and Datura stramonium herbal plant extracts obtained from Kosovo on the polyphenol oxidase enzyme activity were investigated. Polyphenol oxidase from the Poulownia tomentosa plant was purified using the three-phase purification method. It is determined that T. vulgare extract showed the most effective inhibitory effect with 0.43 mg/mL IC50 value. In order to explain and support the binding mechanism of the best inhibitor extract, the phenolic content of the T. vulgare extract was determined by LC-MS/MS and the mechanism of the inhibitory effect was explained by performing a molecular docking study for the phenolic compounds it contained at the highest rate.

Diversity of phenolic compounds, antioxidant capacity, and mineral element content in four fig cultivars (Ficus carica L.) and their correlation with the rooting of hardwood cuttings

We investigated the phenolic compound profile, antioxidant capacity, rooting of cutting and fruit mineral concentration on 15-year-old trees of four Iranian figs (Ficus carica cvs. “Siyah”, “Kashki”, “Shahanjir” and “Sabz”) planted under rain-fed conditions with different fruit skin color, as well as the correlation between these traits. The range of TSS and antioxidant capacity of fruit (without significant differences) was 75.3–76.7°Brix and 87.9–90.3 DPPHsc %, respectively. “Kashki” had the highest total phenolic (TP) (mg GAE/100 g dw) in both the fruit (1964) and the stem bark (1702) and “Sabz” had the lowest flavonoid content (µg CE mg−1 dw) in the fruit (652.3), leaf (1274.5), and stem bark (1501.9). Although the rooting percentage of cuttings was similar in “Siyah”, “Shahanjir”, and “Sabz”, the lowest rooting percentage (62.7%) and the lowest polyphenol oxidase enzyme (PPO) activity (42.5 U.mL−1) were in “Kashki”. Rooting of the cuttings had a direct correlation with PPO activity and catechin and a negative correlation with the TP, vanillin and trans-ferulic acid concentration in cutting bark. These results showed that the fresh cultivar such as “Shahanjir” with outstanding characteristics, such as high potassium and antioxidant content of fruits and good rooting of the cuttings (97.2%) can be recommended for the development programs of light-colored fresh figs. On the other hand, there were two cultivars, “Siyah” and “Kashki” with dark fruit color; due to their content of TP, total flavonoid, quercetin, trans-ferulic acid and high calcium content in the fruit, these should also be considered.

Transcriptional reprogramming in sound-treated Micro-Tom plants inoculated with Pseudomonas syringae pv. tomato DC3000.

Sound vibrations (SV) are known to influence molecular and physiological processes that can improve crop performance and yield. In this study, the effects of three audible frequencies (100, 500 and 1000 Hz) at constant amplitude (90 dB) on tomato Micro-Tom physiological responses were evaluated 1 and 3 days post-treatment. Moreover, the potential use of SV treatment as priming agent for improved Micro-Tom resistance to Pseudomonas syringae pv. tomato DC3000 was tested by microarray. Results showed that the SV-induced physiological changes were frequency- and time-dependent, with the largest changes registered at 1000 Hz at day 3. SV treatments tended to alter the foliar content of photosynthetic pigments, soluble proteins, sugars, phenolic composition, and the enzymatic activity of polyphenol oxidase, peroxidase, superoxide dismutase and catalase. Microarray data revealed that 1000 Hz treatment is effective in eliciting transcriptional reprogramming in tomato plants grown under normal conditions, but particularly after the infection with Pst DC3000. Broadly, in plants challenged with Pst DC3000, the 1000 Hz pretreatment provoked the up-regulation of unique differentially expressed genes (DEGs) involved in cell wall reinforcement, phenylpropanoid pathway and defensive proteins. In addition, in those plants, DEGs associated with enhancing plant basal immunity, such as proteinase inhibitors, pathogenesis-related proteins, and carbonic anhydrase 3, were notably up-regulated in comparison with non-SV pretreated, infected plants. These findings provide new insights into the modulation of Pst DC3000-tomato interaction by sound and open up prospects for further development of strategies for plant disease management through the reinforcement of defense mechanisms in Micro-Tom plants.

Polyphenol Oxidase Enzyme Activity of Mulberries Grown in Iğdir Ecological Conditions

The presence of polyphenol oxidase enzyme (PFO) in black and white mulberry varieties grown in Iğdır province were determined. In the study, no polyphenol oxidase enzyme was detected in the white mulberry varietie, therefore the study was conducted only with black mulberry varieties. The mulberry samples were collected from Iğdır Center, Melekli and Karakoyunlu districts during June and July, both in 2015 and 2016, when the fruits were fully ripe. Mulberries were stored at -20 °C, and the crude enzyme extract was stabilized with pH 5.0 sodium-acetate buffer containing 1% Polyethylene glycol (PEG). To weigh with a precision scale, 20 grams of frozen mulberries were taken into mortars. After the mulberries were thoroughly crushed in these mortars, 40 ml of crude enzyme extract preparation solution was added to each variety and mixed homogeneously. These mixtures were filtered through a cheesecloth and rotated at 4 °C, 10,000 rpm for 30 minutes. The obtained supernatants were used for enzyme solubilization, and the enzyme activity of the solution was determined spectrophotometrically. The PFO content depended on the genotype. There was a significant difference among the tested mulberry genotypes.

Mechanism of enhanced freshness formulation in optimizing antioxidant retention of gold kiwifruit (Actinidia chinensis) harvested at two maturity stages

Kiwifruit exhibits a climacteric ripening pattern and has as an extremely perishable nature. Considering that high perishability leads to a loss in antioxidants and overall nutritional quality. This study aimed to examine the efficacy of enhanced freshness formulation (EFF), a hexanal-based formulation containing antioxidants such as geraniol, α-tocopherol and ascorbic acid, on maintaining the bioactive compounds of gold kiwifruit (cv. ‘Y368’) harvested at two maturity stages. Kiwifruits were treated with three treatments, namely, control (untreated fruit), 0.01 and 0.02% (v/v) EFF. Fruits were treated with 8 weeks of cold storage at 0°C and 90% relative humidity, then transferred to 20°C for 8 days. Three bioactive compounds (ascorbic acid, total phenolics and flavonoids), antioxidant capacities using DPPH and FRAP assays, polyphenol oxidase, ascorbate oxidase, phenylalanine and tyrosine ammonia lyase enzyme activities were evaluated. The results showed that EFF significantly (p < 0.05) influenced bioactive compounds, antioxidant capacities and the activity of enzymes involved in the synthesis and oxidation of bioactive compounds. The maturity stage significantly influenced the content of bioactive compounds. Later harvested kiwifruit had greater content of bioactive compounds, compared to earlier harvested kiwifruit. The total phenolic content was 0.77, 1.09 and 1.22 mg GAE g−1 FW for control, 0.01 and 0.02% EFF, respectively. The FRAP antioxidant concentration was 0.76, 0.91 and 0.96 μmol Fe (II) g−1 FW for control, 0.01 and 0.02% EFF. The findings illustrate the capacity of EFF to optimize bioactive compounds and storability of kiwifruit during postharvest storage.

The influence of the summer pruning on ‘Fuji’ apples storage under controlled atmosphere

This study aimed to evaluate the effect of the summer pruning time in ‘Fuji’ apple trees on the quality of fruit at harvest and after storage in controlled atmosphere with extremely low O2 (CA-ELO) (0.5 kPa O2). The treatments evaluated were summer pruning in December, January, and February, in addition to a control treatment (without summer pruning). The experiment was carried out in the 2018/2019 and 2019/2020 growing seasons. The fruit were evaluated at harvest and after eight months of CA-ELO (0.5 kPa O2 + <0.5 kPa CO2/1.5 ± 0.2°C/92 ± 2% RH) storage, at chamber opening, and after 7 days of shelf-life at 23 ± 3°C and 60 ± 5% RH. The quality of the fruit was evaluated through of soluble solids, flesh firmness, titratable acidity, fruit color, and physiological disorder incidence (sunburn and flesh browning), in addition to enzymatic activity and concentration of functional compounds. There was no significant effect of the summer pruning time on fruit flesh firmness, soluble solids, titratable acidity, and rot incidence after storage under CA-ELO plus 7 days of shelf life. Summer pruning in February resulted in fruit with higher peel red color development, which in general contains a higher concentration of functional compounds at harvest (total phenolic compounds and total antioxidant activity), and lower flesh browning incidence in ‘Fuji’ apples stored under CA-ELO. The nitrogen (N) concentration and nitrogen/calcium ratio (N/Ca) in the second growing season were lower in fruit from plants pruned in February, compared to no summer pruning or earlier pruning. The superoxide dismutase and peroxidase enzyme activity were lower in fruit from treatments with summer pruning in January and February, whereas the polyphenol oxidase enzyme activity was lower when summer pruning was conducted in February.

Effects of antioxidant alfa-lipolic acid on polyphenol oxidase activity of acitretin- methotrexate combination in rat spleen tissue

Objectives: Acitretin, a lipophilic weak acid, is a slightly water-soluble vitamin A analog. Methotrexate is a folic acid analogue and an antimetabolite used for the treatment of many diseases.. Alpha lipoic acid is a nutritional coenzyme with important physiological effects in protein, fat and carbohydrate metabolism. Polyphenol oxidase is an oxidoreductase containing copper in its active site and oxidizes phenolic compounds. The aim of this study is to determine the effect of Alpha lipoic acid on the polyphenol oxidase enzyme activity in the spleen tissue in removing the damage caused by the free radicals produced by Acitretin and Methotrexate at the cellular level. Materials and Methods: Study groups were formed as Control , Alpha lipoic acid , Acitretin+Methotrexate and Acitretin+Methotrexate+Alpha lipoic acid groups. Rats who were starved for 24 hours were injected at the every morning. Acitretin, Methotrexate and Alpha Lipoic Acid were dissolved in 0.9% NaCl and given to rats by intraperitoneal injection. Rats were sacrificed by cervical dislocation on the 7th day after injection. After perfusion of the heart, the spleen was removed. Extracted spleen tissue samples were used for polyphenol oxidase enzyme activity determination. Results: Results: Compared with groups Control; While 18% inhibition was observed in the Alpha lipoic acid group, 20% inhibition was observed in the Acitretin + Methotrexate group. When Alpha lipoic acid was added to the Acitretin + Methotrexate group, while 19% activation was observed according to Control, 1% activation was observed compared to the Acitretin+Methotrexate group. Although there were differences between the groups, these differences were not statistically significant. Conclusion: The inhibition of PPO enzyme activity by ALA can be explained by the fact that while ALA alone acts as a radical scavenger that can regenerate substances with antioxidant properties in the spleen tissue, when given in combination, it acts as an antioxidant that triggers PPO activity.

Carboxymethyl cellulose coating maintains quality of harvested aonla fruit by regulating oxidative stress and ascorbate-glutathione cycle

Aonla is a well-known fruit of medicinal and dietary importance. Nevertheless, it has a short shelf life which is a major constraint in its utilization. In this work, 1% carboxymethyl cellulose (CMC) coating was applied on ‘Banarsi’ aonla and fruit were stored for 10 d at 20 ± 1 ºC. The results exhibited that CMC-coated fruit had lower physiological weight loss, disease incidence, relative electrolyte leakage, hydrogen peroxide (H2O2), malondialdehyde (MDA) and superoxide anion content. The coated aonla exhibited higher L* and lower b* and a* along with markedly lower chlorophyllase (Chl-Phy) and chlorophyll (Chl) degrading peroxidase (Chl-PD) which thereby resulted in higher total Chl content preservation. The CMC coated aonla fruit showed higher superoxide dismutase (SOD), ascorbate peroxidase (APX), peroxidase (POD) and catalase (CAT) along with higher ascorbate-glutathione (ASA-GSH) cycle related attributes. In addition, coated fruit exhibited higher total phenolic and total flavonoid contents along with higher phenylalanine ammonia-lyase (PAL) and reduced polyphenol oxidase (PPO) enzyme activities. On the other hand, juice pH, total soluble solids (TSS) and ripening index (RI) of coated fruit were considerably lower along with substantially higher titratable acidity (TA) content. Therefore, 1% CMC coating could be applied as an appropriate edible layer over aonla fruit to conserve their quality when stored at ambient conditions.

Postharvest Quality Exploration of “Crystal” Grapes in Karst Mountainous Area: Regulatory Effect of High Concentration 1-MCP Fumigation

The comprehensive exploration and thorough understanding of the physicochemical characteristics of “Crystal” grapes in the Karst area of Southwest China can not only produce edible table grapes, but also offer significant theoretical backing for the management of rocky desertification in the Karst area and consequently generate enhanced social and ecological benefits. This study explored the regulatory effect of 1-MCP fumigation on the postharvest storage quality of "Crystal” grapes, aiming to provide some technical support for the development of the grape industry in the Karst mountainous areas. The results indicate that compared with the control group, both the 10.0 and 50.0 μL/L 1-MCP treatment groups effectively inhibited the increase in decay rate, browning rate, shedding rate, and color change of the grapes, significantly inhibited the enhancement of polyphenol oxidase (PPO), peroxidase (POD), and lipoxygenases (LOX) browning-related enzyme activities, improved the superoxide dismutase (SOD) activity of the fruits, hindered the decrease of ascorbic acid (AsA) and polyphenols, delayed the accumulation of malondialdehyde (MDA) content, and significantly postponed the peak period of polygalacturonase (PG) activity in the fruits and the degradation of protopectin to soluble pectin, thereby maintaining desirable texture characteristics. The utilization of 1-MCP for fruit fumigation yielded a heightened overall fragrance, thereby facilitating the emission of terpenes, alcohols, aldehydes, ketone aromatic compounds, and methyl aromatic substances within the fruit. Overall, both the M10 and M50 treatments are equally effective in preserving the storage quality of “Crystal” grapes. Under the condition of ensuring the excellent edible quality of crystal grapes, M2 can extend the shelf life of crystal grapes by about 5 days, and M10 and M50 can extend the storage period of crystal grapes by 10~15 days. Considering the cost, it is recommended that the industry employs a concentration of 10.0 μL/L of 1-MCP for “Crystal” grapes. Simultaneously, this study also provides theoretical support for the ecologically high-quality development of cultivated land in the Karst mountainous area of Guizhou and tree selection.

Effects of Fogging System and Nitric Oxide on Growth and Yield of 'Naomi' Mango Trees Exposed to Frost Stress.

In years with unfavorable weather, winter frost during the blossoming season can play a significant role in reducing fruit yield and impacting the profitability of cultivation. The mango Naomi cultivar Mangifera indica L. has a low canopy that is severely affected by the effects of frost stress. As a result of the canopy being exposed to physiological problems, vegetative development is significantly inhibited. The current investigation aimed to study the influence of spraying nitric oxide and fogging spray systems on Naomi mango trees grafted on 'Succary' rootstock under frost stress conditions. The treatments were as follows: nitric oxide (NO) 50 and 100 μM, fogging spray system, and control. In comparison to the control, the use of nitric oxide and a fogging system significantly improved the leaf area, photosynthesis pigments of the leaf, the membrane stability index, yield, and physical and chemical characteristics of the Naomi mango cultivar. For instance, the application of 50 μM NO, 100 μM NO, and the fogging spray system resulted in an increase in yield by 41.32, 106.12, and 121.43% during the 2020 season, and by 39.37, 101.30, and 124.68% during the 2021 season compared to the control, respectively. The fogging spray system and highest level of NO decreased electrolyte leakage, proline content, total phenolic content, catalase (CAT), peroxidases (POX), and polyphenol oxidase (PPO) enzyme activities in leaves. Furthermore, the number of damaged leaves per shoot was significantly reduced after the application of fogging spray systems and nitric oxide in comparison to the control. Regarding vegetative growth, our results indicated that the fogging spray system and spraying nitric oxide at 100 μM enhanced the leaf surface area compared to the control and other treatments. A similar trend was noticed regarding yield and fruit quality, whereas the best values were obtained when the fogging spray system using nitric oxide was sprayed at a concentration of 100 μM. The application of fogging spray systems and nitric oxide can improve the production and fruit quality of Naomi mango trees by reducing the effects of adverse frost stress conditions.

Boosting biopesticide potential of Trichoderma harzianum for controlling the downy mildew and improving the growth and the productivity of King Ruby seedless grape

BackgroundPlasmopara viticola, the causal agent of grape downy mildew, is one of the most serious grape diseases. Application of Trichoderma harzianum grown on different potato dextrose supplemented broth media using some chemical inducers (TSDCIS), i.e., thiamine (T2), a mixture of micronutrients (T3) and potassium tartrate (T4), compared to Trichoderma without amendment (T1), was conducted under field conditions to evaluate the potential of T. harzianum against grape downy mildew, improving the growth, as well as the yield quality, and quantity.ResultsFoliar application of all TSDCIS significantly reduced the disease severity and increased the phenolic content, peroxidase, polyphenol oxidase enzyme activity, growth parameters, and yield parameters. Trichoderma growing on medium supplemented with potassium tartrate (T4) achieved the most significant reduction in the disease severity (78.9, 81.8%) than the control treatment in two growing seasons, respectively. In contrast, it decreased H2O2 content, lipid peroxidation, and cellular electrolyte leakage. Scanning electron microscopy observations revealed that the number of opened stomata, average stomatal area, and stomatal pore area decreased significantly in response to T4 treatment.ConclusionsIt can be concluded that using Trichoderma growing on medium supplemented with potassium tartrate (T4) to biosafety control the downy mildew disease of grape and improve its growth, yield, and fruit quality is recommended.

Efficient Role of Endophytic Aspergillus terreus in Biocontrol of Rhizoctonia solani Causing Damping-off Disease of Phaseolus vulgaris and Vicia faba.

The wide spread of plant pathogens affects the whole world, threatening national food security. Various fungi including Rhizoctonia solani induce the fungal disease damping-off that negatively affects plant seedlings' growth. Recently, endophytic fungi are used as safe alternatives to chemical pesticides that harm plant and human health. Here, an endophytic Aspergillus terreus was isolated from Phaseolus vulgaris seeds to control damping-off diseases by improving the defense system in Phaseolus vulgaris and Vicia faba seedlings. Endophytic fungus was morphologically and genetically identified Aspergillus terreus, and it is deposited in GeneBank under accession OQ338187. A. terreus demonstrated antifungal efficacy against R. solani with an inhibition zone at 22.0 mm. Moreover, the minimum inhibitory concentrations (MIC) of ethyl acetate extract (EAE) of A. terreus were between 0.3125 and 0.625 mg/mL to inhibit R. solani growth. Precisely 58.34% of the Vicia faba plants survived when A. terreus was added compared with the untreated infected (16.67%). Similarly, Phaseolus vulgaris achieved 41.67% compared to the infected (8.33%). Both groups of treated infected plants showed reduced oxidative damage (reduced Malondialdehyde and hydrogen peroxide levels) as compared to untreated infected plants. Reduced oxidative damage was correlated with the increase in photosynthetic pigments and the antioxidant defense system including polyphenol oxidase, peroxidase, catalase, and superoxide dismutase enzyme activities. Overall, the endophytic A. terreus can be considered an effective tool to control the suppression of Rhizoctonia solani in legumes, especially Phaseolus vulgaris and Vicia faba, as an alternative to synthetic chemical pesticides that harm the environment and human health.

Effects of bacterization on the development of Zea mays during droughts in the conditions of a vegetation experiment

Sustainable agriculture is a concept developed in the late 20th century to promote the production of crops using the biological capabilities of cultivated organisms while minimizing the human impact on agrocenoses. In recent years, the discovery of new types of bacteria that positively impact plant growth has opened up opportunities for the development of effective microbiological preparations and they offer promising prospects for adaptive crop production, enabling farmers to adjust to changing environmental conditions while reducing reliance on anthropogenic inputs. Corn, as the third most important grain crop after wheat and rice, is sensitive to a lack of moisture. Therefore, understanding the mechanisms of adaptation and resistance of this plant to drought remains an urgent task. The aim of the work was to determine the effect of bacterization of Zea mays ("Early gourmet 121") seeds by strains of rhizobacteria on the development of corn under conditions of artificial drought in a vegetation experiment. Strains of bacteria with known properties useful for plant growth and development were used – Bacillus cereus, Pseudomonas putida, Azospirillum brasilense and Azotobacter chroococcum. The study investigated the indicators of seedlings and the content of mono-, oligo-, and soluble sugars in the leaves and the activity of polyphenol oxidase in the roots. The results showed that bacterization of seeds with suspensions of P. putida led to an increase in the length of roots in plants grown under moisture deficit conditions and significantly affected the above-ground parts. Positive effects on the mass of the above-ground parts were observed when seeds were bacterized with suspensions of P. putida, A. chroococcum and a mixture of bacterial suspensions and grown under sufficient irrigation. A similar positive effect occurred when seeds were bacterized only with a mixture of suspensions of the tested bacteria under drought conditions. Bacterization of corn seeds with P. putida or A. brasilense resulted in increased root mass and sugar accumulation in leaves when growing seedlings under conditions of moisture deficit. Additionally, inoculation of P. putida or A. chroococcum seeds increased the activity of polyphenol oxidase enzyme in seedling roots. While the bacteria showed a positive impact on corn development under some conditions, this effect was not observed when there was sufficient moisture. Therefore, we believe that a more promising approach for developing biological preparations based on beneficial microorganisms is to explore combinations of multiple soil bacteria strains. By identifying a mix of bacteria that can effectively stimulate plant growth in both stressed and favourable conditions, we can maximize the potential benefits for crop production. Such combinations of bacteria may enhance plant growth and yield not only during drought stress but also under optimal conditions, providing a more robust and reliable solution for crop management.