POD), Polyphenoloxidase Research Articles

Citrus rootstocks vs. nematodes: A battle for resistance against Tylenchulus semipenetrans

Tylenchulus semipenetrans, the causal agent of the ‘citrus slow decline’, is considered to be the most devastating nematode pest of citrus, causing considerable crop losses throughout the world. The management of this citrus nematode represents a significant challenge due to its wide host range and its adaptability to various environmental conditions. Nematicides application is the most prevalent control approach, however, their use often is associated with increased production costs and major risks to consumer health and the environment. The objective of this study is to contribute to the development of an alternative and effective method to control this plant-parasite. It intends to evaluate the resistance of the seven commonly used citrus rootstocks in Morocco based on their agronomic, physiological, and biochemical behavior in response to inoculation with T. semipenetrans. Results indicated that T. semipenetrans exhibited a strong reproductive capacity on Sour Orange, Australian sour orange, and volkameriana, showing higher root and soil infestation rates, with respectively 466.3, 250.5, and 273.3 females/10 g of root, and 1062.2, 1030.7, and 1053.2 females per 100 g of soil, compared to the other rootstocks varieties. These rootstocks allowed highest T. semipenetrans reproduction rates in both rhizospheric soil (> 3) and root (> 0.68), they also showed the highest infestation rate with more than 3 nematodes per cm of root. Moreover, these rootstocks showed significant biochemical alterations including a sharp increase in the activity of antioxidant enzymes, catalase (CAT), peroxidase (PO), polyphenol-oxidase (PPO), and in proline and malondialdehyde (MDA) accumulation compared to the control and other tested rootstocks. In contrast, T. semipenetrans reproduced poorly (with less than 135 females/10 g of root), less infested the roots (less than 0.33 females/cm of root), and induced slight biochemical modifications in Carrizo citrange. Thus, Carrizo citrange endowed with high resistance to T. semipenetrans could serve as a suitable rootstock to control this citrus devastating nematode.

Defense Inducer Compounds Up-regulated the Peroxidase, Polyphenol Oxidase, and Total Phenol Activities against Spot Blotch Disease of Wheat.

Spot blotch disease of wheat caused by Bipolaris sorokiniana (Sacc.) Shoem is considered as an economically important disease which affects all the growing stages of wheat crop. Therefore, it is important to search some effective management strategies against the spot blotch pathogen. Some synthetic elicitor compounds (salicylic acid, isonicotinic acid, and chitosan) and nano-particles (silver and aluminum) were tested against the pathogen to observe the change in biochemical activity and defense action of wheat plant against spot blotch disease. All the tested elicitor compounds and nano-particles showed a significant increase in activity of peroxidase, polyphenol oxidase (PPO), and total phenol over control. The highest increase in activity of peroxidase was recorded at 72 h from chitosan at 2 mM and 96 h from silver nano-particle at 100 ppm. Maximum PPO and total phenol activity were recorded from chitosan at 2 mM and silver nano-particle at 100 ppm as compared to pathogen-treated and healthy control. The lowest percent disease index, lowest no. of spots/leaf, and no. of infected leaves/plant were found in silver nano-particle at 100 ppm and chitosan at 2 mM, respectively. The use of defense inducer compounds results in significantly up-regulated enzymatic activity and reduced spot blotch disease. Therefore, chitosan and silver nano-particle could be used as alternative methods for the management of spot blotch disease.

Impact of Isonicotinic Acid Blending in Chitosan/Polyvinyl Alcohol on Ripening-Dependent Changes of Green Stage Tomato.

The effect of isonicotinic acid (INA) in a chitosan (CS)/polyvinyl alcohol (PVA) blend on ripening-dependent changes of preserved green tomatoes (Solanum lycopersicum L.) was examined at room temperature. The results showed that CS/PVA/INA 0.5 mM and CS/PVA/INA 1.0 mM formulations retarded firmness loss and delayed the pigmentation parameters i.e., lycopene (LYP), total carotenes (TCs), and titratable acidity (TA). The CS/PVA/INA 0.5 mM and CS/PVA/INA 1.0 mM formulations were able to delay the increase in malondialdehyde (MDA) and total polyphenol (TP) contents. Furthermore, the peroxidase (POD), polyphenoloxidase (PPO), and phenylalanine ammonia-lyase (PAL) activities of tomatoes coated with CS/PVA/INA 0.5 mM and CS/PVA/INA 1.0 mM formulations were lower than those in other treatments. Meanwhile, the CS/PVA blend had the highest TP content, as well as the highest PPO and PAL activities, at the late stage of maturation. The UV analysis showed that the CS/PVA/INA blend film is a promising UV-protective food packaging material. The pure CS, PVA, and INA formulations, as well as the CS/PVA, CS/PVA/INA 0.5 mM, and CS/PVA/INA 1.0 mM formulations, were characterized by infrared (FTIR). The three polymer formulations showed strong antifungal activity against Alternaria alternata and Botrytis cinerea.

Biocontrol Potential of Endophytic Fungi for the Eco-Friendly Management of Root Rot of Cuminum cyminum Caused by Fusarium solani

Root rot disease of Cuminum cyminum caused by Fusarium solani is one of the most destructive diseases threatening cumin production. The present study investigates the biocontrol potential of some endophytes against F. solani and their effect on the induction of defense-related enzymes in a greenhouse. The results herein presented illustrate the strong biocontrol potential of three (out of twelve) endophytes. During the in vitro assay, three isolates demonstrated strong mycelial growth inhibition of F. solani: isolates 3, 4, and 9, with 87%, 65%, and 80% reductions, respectively, with respect to the control (100%). These isolates were identified as Trichoderma harzianum, T. longibrachiatum, and Chaetomium globosum, which produce siderophore and indole-3-acetic acid (IAA). Cumin seed priming with the culture filtrates of T. harzianum, C. globosum, and T. longibrachiatum positively affected the seed germination, as a higher germination (%) of culture filtrate-treated seeds was observed followed by infected and healthy control/untreated seeds. In the greenhouse, the application of T. harzianum, T. longibrachiatum, and C. globosum caused a reduction in disease severity (67.7%, 58.1%, and 59.3%, respectively) on cumin plants, with a lower disease severity (20%, 26%, and 25%, respectively) recorded in treated plants compared to the infected control (62%). Furthermore, a significant increase in defense-related enzymes in culture filtrate-treated cumin plants was recorded. Higher peroxidase (PO), polyphenoloxidase (PPO), and phenylalanine ammonia-lyase (PAL) activity, and a higher content of phenolic compounds, were found in culture filtrate-treated plants. These results indicate that the culture filtrates of these bioagents not only increased seed germination, but also protected the plants from F. solani infection by acting as important elements of the cellular antioxidant system in plants upon infection, conferring the biocontrol potential of C. globosum and Trichoderma species toward mitigating the root rot disease of cumin plants in a greenhouse.

Endophytic fungus Bipolaris sp. CSL-1 induces salt tolerance in Glycine max.L via modulating its endogenous hormones, antioxidative system and gene expression

ABSTRACT Salinity stress is one of the most serious environmental stress that inhibits plant growth. In this study, we adopted an environment friendly technique and screened different plant growth-promoting fungi for different plant growth promoting (PGP) traits and salinity stress. Among those isolates, Bipolaris sp. CSL-1 was selected based on plant growth-promoting characteristics, such as producing indole-3-acetic acid (IAA), gibberellins (GAs), organic acids and resistance to sodium chloride (NaCl) stress. Here, we found that inoculating soybean with isolate CSL-1 significantly increased shoot and root length, shoot and root fresh and dry weight and chlorophyll content under NaCl stress (200 mM). Endogenous abscisic acid (ABA) levels were significantly decreased, whereas salicylic acid (SA) levels were increased in CSL-1-inoculated plants under NaCl stress. NaCl-treated noninoculated plants showed higher levels of antioxidants and oxidative stress such as peroxidase, polyphenol oxidase (PPO), malondialdehyde (MDA) and superoxide anion (SOA). Furthermore, CSL-1 inoculation improved soybean resistance to NaCl stress, and there was a significant decrease in GmFDL19, GmNARK, and GmSIN1 expression levels. As a result, the fungal isolate CSL-1 mitigates the effect of salt stress and enhance soybean growth and might be used as a valuable ecofriendly microorganism resource in salt-affected areas.

Traceability of tomatoes (Solanun lycopersicum) based on their enzymatic profile

This study aimed at evaluating the effect of organic and conventional farming systems on enzymatic profiles of tomatoes so as to find a biomarker for their safe traceability and certification. Three tomato varieties (Khaki, Italian and Cherry), officially certificated and sold in fruit shops, were collected in different seasons. The fruits of each variety were standardized in analytical samples in relation to their ripeness indicators (color, sugar/acidity rate). Assays used for determining enzymatic activities were previously standardized to invertases (INV), polygalacturonases (PG), peroxidases (PO), polyphenoloxidases (PPO), catalases (CAT) and phenylalanine ammonia lyase (PAL). Enzymatic activities were correlated with the farming systems by the Principal Component Analysis (PCA). Enzymatic activities of PO, PPO, CAT and PAL proved to be useful for tomato certification and traceability, since their correlation was above 0.9. The statistical analysis confirmed that PO and CAT activities were the most promising to find a model of response to the farming system. Enzymatic profiles of both Italian and Cherry varieties were the most affected by the farming system.

Efficacy of Compost and Some Biocontrol Agents in Controlling Cucumber White Mould Disease under Protected House Conditions

Five different Trichoderma isolates and three different bacterial genera (Serratia marcescens, Bacillus subtilis, Pseudomonas fluorescens) were used in the present study either separately or combined with compost to evaluate their biocontrol potential against Sclerotinia sclerotiorum either in vitro or in vivo. The results showed that all tested bioagents significantly affected the radial growth of the pathogen under laboratory conditions. The highest reduction (61.85%) was detected with isolates T. asperellum followed by T. album which inhibited the radial growth by 60.74%. The combination between T. viride + T. asperellum + T. album was the most effective in reducing disease severity during both seasons and increased yield up to 2.5 kg/plant. The influence of the tested biocontrol fungi and bacteria on essential lysis enzymes activity i.e. chitinase and Beta 1,3- glucanase was investigated. The results showed that both tested fungal and bacterial agents alone or combined with compost affected the activity of both enzymes positively. Similar findings were observed with aspect to three different oxidative enzymes activity i.e. peroxidase (PO), polyphenoloxidase (PPO) and phenylalanine ammonia lyase (PAL). The profiling of peroxidase activity was induced in treated cucumber plants. Moreover, the results revealed that treating cucumber plants with the investigated bioagents expressed new protein bands.

Quantitive changes of enzyme activity in wheat induced by Streptomyces sp. Strain HU2014

Biocontrol microorganism have a diverse range of activities and they have been focused on potential biocontrol agents in agriculture. They can induce plant defensed response and enhance plant disease resistance. Streptomyces sp. produce active metabolites that can inhibit the growth of phytopathogens. Induced resistance is usually indicated by the activity of Peroxidase (POD), Polyphenoloxidase (PPO), and Phenylalanine ammonia-lyase (PAL) or other defense enzymes. The related reports mainly focused on disease control or promoting growth of cash crops or vegetables, but less on wheat presently. Moreover, the information about the concentration of fermentation broth and mycelia of Streptomyces affected the quantitative changes of defensed enzyme activities is limited. In this study, we started from isolating a Streptomyces strain, named S. sp. strain HU2014, and demonstrated (POD), (PPO), (PAL) enzymes in different concentration of the mycelia (M) and extracellular filtrate (EF) of the strain with the application of soil drench treatment. The enzyme activities were determined by visible spectrophotometry. The results showed that the activities of POD and PAL at the concentration of 103-fold dilution of the EF increased significantly to some extent in comparison with untreated control, by 173.86 % (P < 0.05) and 71.92 % (P < 0.05), respectively. In the range of different concentration of the M, POD and PPO activities were enhanced with the increasing of dilution ratio, but the difference was not significant. It is expected to be an excellent resource for the development of new biological preparations.

Antifungal action and induction of resistance by β-aminobutyric acid against Penicillium digitatum to control green mold in orange fruit

Green mold, caused by Penicillium digitatum, is the most economically important postharvest disease of orange fruit worldwide. The aim of this study was to evaluate the effect of β-aminobutyric acid (BABA) treatment on the inhibition of P. digitatum both in orange fruit and in vitro as well as the possible mechanisms of action. BABA at 125 mM significantly inhibited mycelial growth, spore germination, and germ tube elongation of P. digitatum by 93.3, 90.3, and 90.5%, respectively. The relative electrical conductivity of mycelium was increased for a period of 0–36 h after treated with BABA at 125 mM. Furthermore, BABA caused a high level of malondialdehyde (MDA) in P. digitatum mycelia during four days of incubation. The ergosterol content in the plasma membrane of P. digitatum was significantly lower in BABA-treated mycelia. Also, protein and sugar leakage were increased with BABA treatment compared with that in the control. Besides, BABA caused a considerable reduction in the total lipid content of P. digitatum mycelia at 125 mM. Scanning electron microscopy (SEM) of P. digitatum treated with BABA at 125 mM showed shrunken, distorted, and collapsed mycelia. The application of BABA at 125 mM in orange fruit inoculated with P. digitatum suppressed disease incidence and disease severity by 74.6 and 77.3%, respectively, compared to untreated fruit. Moreover, the activity of defense-related enzymes, including peroxidase (POD), polyphenoloxidase (PPO), and phenylalanine ammonia-lyase (PAL) were significantly enhanced in the orange fruit treated with BABA at 125 mM.

Enhancing Biocontrol Agents by Hydroquinone and Salicylic Acid for Controlling Root-Rot and Wilt Diseases of Lupine

Utilization of Trichoderma harzianum and Bacillus subtilis as biocontrol agents and chemical inducers hydroquinone (HQ) and salicylic acid (SA) as plant systemic inducers resistance individually or in combinations was studied for controlling root rot and wilt diseases and growth promoting of lupine plants in vitro and in vivo. Both antagonistic bioagents and chemical inducers either individually or in combination inhibited linear growth of Fusarium oxysporum f.sp. lupini and Rhizoctonia solani with variable degrees compared to the check. Bacillus subtilis + HQ and B. subtilis + SA recorded the highest reduction of mycelial growth in both pathogenic fungi. Under the greenhouse and field conditions, all treatments significantly reduced damping-off and root rot/wilt incidence and increased the survived plants. The combination of biocontrol agents and chemical resistance inducers were more effective than using each of them individually. Also, under field conditions, these treatments significantly increased plant growth parameters and yield components in both locations (Ismailia and Sers El-layian Res. Stations Farms during 2017/2018 growing season). In physiological studies, photosynthetic pigments, activities of defense-related enzymes, including peroxidase (PO), polyphenoloxidase (PPO) and total phenols content (TPC) were increased in plants treated with biocontrol agents combined with chemical inducers compared to using each of them individually. Generally, the combination of biocontrol agents and chemical resistance inducers recorded the best results for controlling damping-off, root rot/wilt diseases, plant growth parameters and yield components in the greenhouse and field. Such these treatments may be used as a part of integrated disease management for field crops in order to avoid the use of fungicides.

Responses of wheat to zinc sulfate fertilizer and plant growth‐promoting rhizobacteria under cadmium stress in soil

AbstractCadmium (Cd) is a major pollutant in soils as a result of extensive use of fertilizers, mining and industrial discharges. Zinc (Zn) and certain bacterial species have been known to alleviate Cd toxicity in plants. In this study, the individual and combined effects of the application of Zn and Pseudomonas species with the aim of reducing Cd stress in wheat cultivars were investigated. Plants (durum wheat and bread wheat) were exposed to different concentrations of Cd and Zn, and either P. putida or P. fluorescens in a growth chamber. Concentrations of Zn, Cd, chlorophyll (Chl), carotenoid, hydrogen peroxide (H2O2), and malondialdehyde (MDA), as well as antioxidant enzyme activities were assayed. The addition of Zn in soils reduced the toxicity of Cd in durum wheat more than in bread wheat even though there was more uptake of Zn in bread wheat. Analysis of variance showed that by using Zn fertilizer and Pseudomonas species the amounts of peroxidase (POD), polyphenoloxidase (PPO), MDA, and H2O2 were reduced at three growth stages. Surprisingly, with increasing Zn concentration, Cd concentration in plant tissue was slightly increased, which suggests that adding Zn to soil could facilitate Cd desorption from soil particles. Application of Pseudomonas and Zn could be a promising solution to reduce detrimental effects of Cd, especially in durum wheat.

Systemic Resistance in Snap Bean (Phaseolus vulgaris L.) Elicited by Some Chemicals and Biotic Inducers Against White Mold Disease Caused by Sclerotinia sclerotiorum

The effect of chemicals and biotic inducers i.e., Bion [benzothiadiazole (BTH)], Salicylic acid (SA), Bacillus subtilis and Trichoderma harzianum as seed treatments of snap bean (Phaseolus vulgaris L. cv. Paulista.) compared to the fungicide Topsin M-70, were evaluated in the greenhouse and under field conditions during the two successive growing seasons 2016/2017 and 2017/2018 at Ashmoun, Menoufia Governorate, Egypt to control the white mold disease caused by Sclerotinia sclerotiorum (Lib.) de Bary. All the tested chemicals and biotic inducers treatments significantly reduced the percentages of pre- and post-emergence damping-off compared with the untreated control under greenhouse conditions. The highest percentage of survived plants was achieved by Topsin M-70 and Bion, followed by B. subtilis, Salicylic acid, and T. harzianum. Activities of defense-related enzymes peroxidase (PO), polyphenoloxidase (PPO) enzymes, and phenol content were determined. Bion treatment showed the highest increase in PO and PPO activity and total phenols followed by B. subtilis, Salicylic acid, and T. harzianum treatments in the presence of S. sclerotiorum. In the two successive growing seasons under field conditions, all the tested chemicals and biotic inducers treatments reduced the percentage of white mold incidence and severity of the treated snap bean plants compared with the untreated control. The highest reduction of disease incidence and severity was recorded by Topsin M-70 followed by Bion, B. subtilis, Salicylic acid,and T. harzianum, respectively. As well as, all treatments significantly increased vegetative characteristics i.e., plant height, No. of branches/plant, plant fresh and dry weight, and yield parameters i.e., average pod weight (g) and yield (ton/fed). Furthermore, chemical composition of green pods showed a significant increase in protein and carbohydrates content (%) beside all minerals Nitrogen (N), Phosphorus (P) and Potassium (K) content as compared with the untreated control in the two growing seasons.

Rice defense responses to Bipolaris oryzae mediated by a strobilurin fungicide

Strobilurins, also known as quinone outside inhibitors (QoIs), are one of the most important fungicide groups for controlling plant diseases. In addition, they can prime plants for enhanced defense against pathogen attack. Here, detailed biochemical and microscopic analyses were performed to investigate whether azoxystrobin (Az) could enhance defense responses to Bipolaris oryzae, the cause of brown spot of rice. Fungal infection increased the activity of all defense enzymes regardless of fungicide treatment. Az-sprayed plants displayed higher activities of β-1,3-glucanase, peroxidase, polyphenol oxidase (PPO) and lipoxygenase (LOX) in the absence of B. oryzae inoculation and of phenylalanine ammonia-lyase, PPO and LOX at 24 h after inoculation (hai) with B. oryzae compared to the control plants. Concentrations of total soluble phenols at 144 hai were higher in the Az-sprayed plants relative to their non-treated counterparts. Concentrations of lignin-thioglycolic acid derivatives were increased following fungal infection in the control plants. Hyphae from B. oryzae colonized bulliform, bundle sheath, epidermal, guard, mesophyll and vascular bundle cells besides intercellular spaces, but fewer and smaller fungal cells were noticed in the Az-sprayed than in the control plants. Therefore, although Az transiently reprogrammed activities of some defense enzymes, its fungicidal activity appears to have played a major role in reducing B. oryzae infection.

Silicon induces resistance to postharvest rot of carrot caused by Sclerotinia sclerotiorum and the possible of defense mechanisms

The inhibitory potential of silicon (Si) against Sclerotinia sclerotiorum, the causal agent of postharvest carrot rot was investigated under in vitro and in vivo conditions, and possible modes of action were evaluated. Silicon at the concentration of 10 mM strongly decreased the mycelial growth of S. sclerotiorum by 92.2% with inhibition of sclerotia formation by 76.3%. Myceliogenic and carpogenic germination of S. sclerotiorum sclerotia were inhibited by 89.1 and 78.9%, respectively, at the same concentration. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) values were 12 and 30 mM, respectively. Cell membrane permeability and lipid peroxidation of S. sclerotiorum mycelia were increased with Si treatment. Silicon at 10 mM significantly decrease the content of oxalic acid in S. sclerotiorum mycelia compared to the control. Application of silicon at 10 mM reduced the incidence of sclerotinia rot in carrot roots by 60.6% with 40 mm lesion length. Silicon treatment enhanced the activities of peroxidase (POD), polyphenoloxidase (PPO) and phenylalanine ammonia-lyase (PAL) in carrot roots inoculated with S. sclerotiorum. These results confirm that silicon might applied as an alternative tool to chemical fungicides for controlling sclerotinia rot of carrot during storage and to promote the defense response in carrot.

Root priming with Bacillus spp. against bacterial wilt disease of tomato caused by Ralstonia solanacearum

Bacillus spp. have long been used as biological control organisms against plant bacterial diseases but the mechanisms by which the bacteria confer protection against the pathogens are not properly understood. Among nine strains of Bacillus spp. three of them, viz. NBAII 63 (B. megaterium), NBAII 71 (B. cereus) and NBAII 65 (B. megaterium) were found highly inhibitory against R. solanacearum. These strains of Bacillus spp. produced indole acetic acid (IAA) and siderophore and solubilized the phosphorous. High amount of IAA (174.2 μg/ml) and siderophore (1.32μg/ml) production followed by the highest phosphorous solubilization (53.3 μg/ml) by the strain NBAII 63 were found. These three potential Bacillus strains showed the increased activity of defense related enzymes, viz. peroxidase (PO), polyphenoloxidase (PPO), phenylalanine ammonia-lyase (PAL) and total phenols in pre treated tomato plants challenged with R. solanacearum. Significant activities of PO, PPO, PAL were observed at 8 days after the treatment of antagonist and declined gradually afterwards. The maximum phenol content (185 μg/g of plant tissue) was observed in the tomato plants whose roots were treated with Bacillus strain 63 at 8 days after inoculation treatment. These Bacillus strains could be used as potential biocontrol agent for the management of bacterial wilt disease of tomato.

Effect of Klebsiella pneumoniae on speck disease development in Solanum lycopersicum

Colonisation and infection of Pseudomonas syringae pv. tomato is governed not only by host resistance but also by its interactions with other phylloplane bacterial colonizers. In the present study, reduced disease symptoms were observed as a result of interaction between P. syringae pv. tomato and Klebsiella pneumoniae, a predominant human enteric pathogen colonising phyllosphere. Tomato (Solanum lycopersicum) plants raised under controlled aseptic conditions were divided into 4 groups of 25 plants each and treated as follows: Group 1- inoculated with P. syringae pv. tomato; Group 2- inoculated with K. pneumoniae; Group 3- combination of P. syringae pv. tomato and K. pneumoniae (1:1); Group 4- Distilled water (control). Sampled leaves from the above groups were analysed at 24, 48, 72 and 96 hours post inoculation for the activity of cytoplasmic Peroxidase (POX), Polyphenoloxidase (PPO) and Phenylalanine ammonia lyase (PAL). Disease incidence was recorded in treated as well as leaves emerging after 2 weeks of inoculation. Plants treated with P. syringae pv. tomato had maximum disease incidence while no infection was observed in control and those inoculated with K. pneumoniae alone. Inoculation of plants with combination of both microbes could substantially reduce the disease severity. The results thus demonstrate that K. pneumoniae, a common HEP on plant surfaces, reduces the ability of P. syringae pv. tomato to colonise the host.

Effectiveness of Plant Extracts as Safe Control Means against Damping-off and Root Rot Diseases in Faba Bean Plants

Faba bean root rot caused by Fusarium solani and Rhizoctonia solani is one of the most important biotic stresses in the major growing areas in Egypt. In this study, aqueous extracts and organic solvent extracts of three wild medicinal plants (Lawsonia inermis, Eugenia jambolana and Moringa oleifera) were evaluated in vitro and in vivo for protection of faba bean plants against damping-off and root rot diseases. Under laboratory conditions, all aqueous and organic solvent extracts significantly suppressed linear growth of F. solani and R. solani. E. jambolana extracts recorded the highest inhibition to the linear growth of both pathogenic tested fungi. Also, organic solvent extracts were more active than aqueous extracts of all tested plants. Under greenhouse and field conditions, all tested extracts significantly reduced damping-off and root rot incidence as well as increased some crop parameters in the field compared with untreated control. Faba bean seeds treated with E. jambolana extracts gave the highest protection against damping-off and root rot as well as recorded the highest crop components compared to the other extracts. In physiological studies, activity of defense-related enzymes, including peroxidase (PO), polyphenoloxidase (PPO), phenylalanine ammonia lyase (PAL), superoxide dismutase (SOD) and catalase (CAT), as well as content of phenolic compounds were increased in plants treated with aqueous or organic solvent extracts grown in soil infested with any of F. solani and R. solani, compared with untreated plants (control). In general, E. jambolana extracts recorded the highest increase in the activity of all enzymes as well as the content of total phenolic compounds. The organic solvent extracts increased the activity of all assessed enzymes and total phenolic compounds more than aqueous extracts of all tested plants. These results suggested that aqueous and organic solvent extracts may play an important role for controlling faba bean damping-off and root rot diseases.

Role of some Non-traditional Compounds in Managing Sugar Beet Powdery Mildew

Certain non-traditional compounds such as compost tea, humic acid and sulphated canola oil were tested as foliar application to evaluate their efficacy to induce systemic resistance against Erysiphe betae, the causal agent of powdery mildew in sugar beet (Herkl cv.) versus the traditional fungicide Opera under greenhouse and field conditions at Gemmeiza Agricultural Research Station, Agricultural Research Center (A.R.C.), Egypt during two successive winter seasons (2014/2015 and 2015/2016). Under greenhouse conditions, results revealed that spraying plants with all the tested compounds reduced disease severity of powdery mildew. The fungicide Opera was the most effective treatment in reducing disease severity and increasing the efficacy followed by Sulplex, compost tea and humic acid. Also, all treatments significantly increased total phenols and orthodihydric (OD) phenol content of the leaves compared to the control 15, 30 and 45 days after inoculation. Also, spraying plants with the tested compounds increased the activity of peroxidase (PO), polyphenoloxidase (PPO) and chitinase enzymes compared to the control, 15, 30 and 45 days after artificial inoculation. Inthe detection of chitinase activity by using SDS-glycol chitin polyacrylamide gel electrophoresis the molecular weight for all samples ranged from 28 to 30 kDa. high intensity band expressing the highest chitinase activity was found in compost-tea treatment followed by Sulplex. Moreover, control, fungicide Opera and humic acid treatments showed low chitinase activity. Under field experiments, results indicated that the fungicide Opera was the most effective treatment for controlling powdery mildew followed by Sulplex and compost tea. Meanwhile, humic acid was the lowest effective one in this regard. All treatments increased root yield per feddan compared to the control. The fungicide Opera and Sulplex gave the highest root yield per feddan followed by compost tea then humic acid. Moreover, compost tea and Sulplex gave the highest percentages of total soluble solids (T.S.S.), sucrose percentages in beet roots and purity.

Quality, antioxidant compounds, antioxidant capacity and enzymes activity of ‘El-Bayadi’ table grapes at harvest as affected by preharvest salicylic acid and gibberellic acid spray

Berry quality, antioxidant compounds, antioxidant capacity and enzymes activity of ‘El-Bayadi’ table grapes cultivar at harvest as affected by preharvest spray of salicylic acid (SA, 4.0mM) and gibberellic acid (GA3, 30mg/L) were evaluated during 2014 and 2015 seasons. GA3 spray increased berry weight, length and width compared to SA and control treatments. SA spray decreased berry length and width compared to control. Both cluster weight and length increased by SA and GA3 compared to control. TSS content was not affected by treatments, but was higher in 2015 than 2014 season. Titratable acidity was higher at GA3 and SA treatments than control and was higher in 2014 than 2015 season. TSS/acid ratio was lower at SA than GA3 and control treatments. Berry firmness was lower at SA than GA3 and control treatments and was higher in 2014 than 2015 season. Total phenols and flavonoids concentrations were higher at SA and GA3 treatments than control. trans-resveratrol concentration increased, while trans-piceid decreased by SA spray compared to GA3 and control treatments. Total phenols concentration was higher in 2015 than 2014 season, in contrast to total flavonoids and trans-resveratrol. Vitamin C concentration increased by GA3 spray compared to SA and control and was higher in 2015 season than 2014. Peroxidase (POD) polyphenoloxidase (PPO), polygalacturonase (PG) and xylanase activities increased by GA3 spray compared to SA and control. While, SA spray decreased both POD and PPO activities compared to control. Both SA and GA3 spray lowered antioxidant capacity (higher DPPH IC50 values) than control. Nitrogen, phosphorus and potassium, and protein concentrations were higher at SA and GA3 treatments than control. In conclusion, preharvest spray of SA and GA3 could be used to improve the overall quality ‘El-Bayadi’ table grapes.

Integrated Management of Tomato Sclerotinia Rot Disease by using the Combined Treatments between Compost, Bioagents and some Commercial Biocides

Efficacy of compost, bioagents and some commercial biocides individually or in combination for controlling tomato sclerotinia rot caused by Sclerotinia sclerotiorum (Lib.) de Bary under greenhouse and field conditions were studied. Results indicated that Trichoderma album and Bacillus subtilis were the most effective bioagents in inhibiting mycelial growth of S. sclerotiorum in vitro. All treatments significantly reduced disease incidence and severity of tomato white rot disease compared with untreated control. However, T. album and Pseudomonas fluorescens combined with compost reduced the disease incidence and disease severity from 100 and 77.40 in control to 11.1 & 1.5% and 11.1 & 2.5%, respectively, under greenhouse conditions. The integrated T. album, P. fluorescens and Bio-Zeid with compost recorded the highest increase of fresh weight and dry weight of shoots and roots compared with individual treatments and control. Under field conditions, adding compost to the soil pre-transplanting decreased the percentage of infection and increased yield of tomato plants compared with other treatments with compost. In this respect, the integration between T. album + B. subtilis + Ps. fluorescens and compost was the most effective treatment for reduced the disease incidence and disease severity. As well as, this treatment increased the fruit weight per plant. On the side, all treatments increased the phenols and flavonoids content in tomato plants. The highest increase in the total phenols and flavonoids contents were recorded with T. album, P. fluorescens and Bio-Zeid combined with compost. Also, all treatments increased peroxidase (PO), polyphenoloxidase (PPO), chitinase and β-1, 3- glucanase activities in treated tomato plants. It could be concluded, the combination between compost, bioagents and some commercial biocides might be useful as an useful tool for controlling tomato sclerotinia disease under greenhouses and field conditions.