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Changes in peroxidase and polyphenol oxidase activities in susceptible and resistant wheat heads inoculated with Fusarium graminearum and induced resistance

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... On the other hand, we have noted an activation of polyphenoloxidases (PPO), enzymes involved in the oxidation of phenolic compounds into quinones that participate in the linkage of the different constituents of the wall and consequently increase its rigidity (Avdiushko et al., 1993 andEl Modafar 2010). Other studies have reported the involvement of polyphenol oxidases in plant resistance to pathogens (Mohammadi andKazemi, 2002 andCooper et al., 2004). Mycorrhization promotes stimulation of POX and PPO activities during water stress (25% FC), we also noted an exaltation of these defense mechanisms that remains dependent on the fungal isolate. ...
... On the other hand, we have noted an activation of polyphenoloxidases (PPO), enzymes involved in the oxidation of phenolic compounds into quinones that participate in the linkage of the different constituents of the wall and consequently increase its rigidity (Avdiushko et al., 1993 andEl Modafar 2010). Other studies have reported the involvement of polyphenol oxidases in plant resistance to pathogens (Mohammadi andKazemi, 2002 andCooper et al., 2004). Mycorrhization promotes stimulation of POX and PPO activities during water stress (25% FC), we also noted an exaltation of these defense mechanisms that remains dependent on the fungal isolate. ...
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Date palm (Phoenix dactylifera L.) is an important agricultural and commercial crop in the North of Africa and Middle Eastern countries of Asia. Date palm tree could be used for generations to come due to its remarkable nutritional, health and economic value in addition to its esthetic and environmental benefits. During the last decade, date palm plantations were subjected to degradation due to an extensive exploitation and to drastic environmental conditions. The major problems of drought and salinity have become more intense over time and their negative impacts on palm crop are marked by decreasing the production of phoenix dactylifera. Furthermore, fusarium wilts (bayoud) are economically important soil-borne diseases that result in significant crop losses and damage to natural ecosystems. Bayoud is a vascular wilt caused by Fusarium oxysporum f. sp. albedinis (Foa), and it is the most serious fungal disease threatening date palm plantations. This vascular disease combined with the problems of drought caused huge losses in our palm groves destroying more than 12 million trees and reducing the total areas from 150 000 to 44 000 Ha approximately. Plant-microbe interactions can be either beneficial or detrimental and a fast and accurate assessment of the surrounding organisms is essential for the plant's survival. Arbuscular mycorrhizal fungi (AMF) are a major component of soil biofertility and its use can improve crop resistance to biotic and abiotic stresses. This study highlights the importance of AMF in increasing tolerance of date palm to both Fusarium oxysporum f. sp. albedinis; a root-infecting fungal pathogen that causes wilt disease on a broad range of plant species, and to water-deficit. Initially, date palm seedlings were inoculated with four AMF spores: Glomus monosporus, Glomus clarum, Glomus deserticola and Consortium "Aoufous" (indigenous AMF), and cultivated for 14 months. Our results revealed that after this period, mycorrhizal infection rates were higher and slightly affected by water stress. The inoculation by the Consortium Aoufous, G. monosporus or G. clarum increased biomass production of date palm instead of the attacks by the fungal pathogen F. oxysporum, whatever the water regime. AMF allowed leaf water parameters to be maintained in F. oxysporum-inoculated plants or not under water-limiting conditions. The mortality rate among the date palm trees infected by F. oxysporum was lower in mycorrhizal plants than nonmycorrhizal plants. Results showed also that AMF decrease the deleterious effect of F. oxysporum on date palm, nevertheless the bioprotection effect against the plant pathogen was dependant on the type of AMF species. It therefore seems that the indigenous AM fungal communities "Aoufous" take advantage to improve crop resistance to those harsh biotic and abiotic conditions.
... a primary metabolism enzyme of phenylpropanoids seems to play an important role in the synthesis of many secondary defense-related compounds, such as phenols and lignin (Tahsili et al., 2014). Polyphenol Oxidase (PPO) (EC 1.10.3.2) another defense-related enzyme is considered to catalyze phenol oxidation to quinones that are harmful to pathogens (Mohammadi and Kazemi, 2002). These enzymes are increasingly critical in the direct resistance of plants to pathogenic agents. ...
... Polyphenol Oxidase (PPO) participates in polyphenol oxidation into quinones and plant cell lignification during microbial invasion (Mohammadi and Kazemi, 2002). The function of the PPO is latent until destructive forces such as wounding, senescence, or assault by insect pests or pathogens release the enzyme from the thylakoid (Thipyapong et al., 2004). ...
Article
Plants are the ecosystem's primary source and have a direct or indirect impact on human life. Pathogens and insect's interference into the plants contribute to enormous losses in yield and productivity. Pathogens that can invade plants capable of recognizing and responding to their attack by activating security systems. This activation requires signal transmission from the receptor to the cell gene. Recently, signal molecules have been discovered that are involved in signal transmission induced in response to biological stresses. Accumulated data indicate the presence of a dynamic and well-integrated bio-signal mechanism in plant cells. Controls plant defense responses to these net pathogen attacks.
... a primary metabolism enzyme of phenylpropanoids seems to play an important role in the synthesis of many secondary defense-related compounds, such as phenols and lignin (Tahsili et al., 2014). Polyphenol Oxidase (PPO) (EC 1.10.3.2) another defense-related enzyme is considered to catalyze phenol oxidation to quinones that are harmful to pathogens (Mohammadi and Kazemi, 2002). These enzymes are increasingly critical in the direct resistance of plants to pathogenic agents. ...
... Polyphenol Oxidase (PPO) participates in polyphenol oxidation into quinones and plant cell lignification during microbial invasion (Mohammadi and Kazemi, 2002). The function of the PPO is latent until destructive forces such as wounding, senescence, or assault by insect pests or pathogens release the enzyme from the thylakoid (Thipyapong et al., 2004). ...
Article
Plants are the ecosystem's primary source and have a direct or indirect impact on human life. Pathogens and insect's interference into the plants contribute to enormous losses in yield and productivity. Pathogens that can invade plants capable of recognizing and responding to their attack by activating security systems. This activation requires signal transmission from the receptor to the cell gene. Recently, signal molecules have been discovered that are involved in signal transmission induced in response to biological stresses. Accumulated data indicate the presence of a dynamic and well-integrated bio-signal mechanism in plant cells. Controls plant defense responses to these net pathogen attacks.
... These proteins have a role in catalyzing various substrates oxido-reduction through H2O2 [100]. Peroxidases are involved in wall-building processes, e.g., oxidation of phenols, suberization, and lignification of host cells during the defense reaction against pathogenic agents [101]. Therefore, these are essential mechanisms related to the response of plants against pathogen attacks. ...
... These changes could increase the cell walls' efficiency to become barriers that slow down the dispersal of a disease. Moreover, enhanced POD activity is considered to improve resistance against pathogens in rice [102] and wheat [101]. ...
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Anthracnose, caused by Colletotrichum gloeosporioides, is one of the most damaging pepper (Capsicum annum L.) disease. Melatonin induces transcription of defense-related genes that enhance resistance to pathogens and mediate physiological activities in plants. To study whether the mela-tonin-mediated pathogen resistance is associated with chitinase gene (CaChiIII2), pepper plants and Arabidopsis seeds were treated with melatonin, then CaChiIII2 activation, hydrogen peroxide (H2O2) levels, and antioxidant enzymes activity during plant-pathogen interactions were investigated. Melatonin pretreatment uncoupled the knockdown of CaChiIII2 and transiently activated its expression level in both control and CaChiIII2-silenced pepper plants and enhanced plant resistance. Suppression of CaChiIII2 in pepper plants showed a significant decreased in the induction of defense related genes and resistance to pathogens compared with control plants. Moreover, melatonin efficiently enabled plants to maintain intracellular H2O2 concentrations at steady-state levels and enhanced the activities of antioxidant enzymes, which possibly improved disease resistance. The activation of the chitinase gene CaChiIII2 in transgenic Arabidopsis lines was elevated under C. gloeosporioides infection and exhibited resistance through decreasing H2O2 biosynthesis and maintaining H2O2 at a steady-state level. Whereas melatonin primed CaChiIII2-overexpressed (OE) and wild-type (WT) Arabidopsis seedlings displayed a remarkable increase in root-length compared to the unprimed WT plants. Using an array of CaChiIII2 knockdown and OE, we found that melatonin efficiently induced CaChiIII2 and other pathogenesis-related genes expressions, responsible for the innate immunity response of pepper against anthracnose disease.
... O tratamento de fosfito de potássio aumentou 79,9 % a atividade da PFO, indicando possivelmente que estes produtos induzem a atividade enzimática da PFO e mecanismos de defesa relacionados com o aumento de compostos relacionados com o espessamento da parede celular, fato relatado em plantas infectadas com Fusarium graminearum (MOHAMMADI; KAZEMI, 2002). ...
... Fenóis totais H2O2 A concentração de fenóis totais foi reduzida nas plantas pulverizadas com todos os produtos exceto com silício que aumentou o teor de fenóis totais em 50,2 % em relação à testemunha em todas as avaliações. É importante notar que o teor de fenóis totais em plantas de rosas tratadas com fosfito de potássio foi significativamente reduzido (tabela 2), o que está relacionado ao aumento da POD e da PFO, uma vez que os fenóis são substratos dessas enzimas, para produzir lignina e outros compostos relacionados às respostas de defesa de plantas a patógenos (MOHAMMADI; KAZEMI, 2002). ...
... In the presence of humic acid (potassium humates), peroxidase activity was significantly increased by all treatments in comparison with seedlings grown in the infested control except Bacillus subtilis where the increase in peroxidase activity was not significant. Many investigators stated that there is positive relationship between peroxidase enzyme and resistance developed in plants (Mohammadi andKazemi, 2002 andChen et al., 2000). ...
... In the presence of humic acid (potassium humates), peroxidase activity was significantly increased by all treatments in comparison with seedlings grown in the infested control except Bacillus subtilis where the increase in peroxidase activity was not significant. Many investigators stated that there is positive relationship between peroxidase enzyme and resistance developed in plants (Mohammadi andKazemi, 2002 andChen et al., 2000). ...
... Subsequently other transformed plants viz., F+V-93 and FTF-215, it varies significantly from each other, where the PPO activity ranged between 56.3 and 62.3unit mg -1 protein. Similar findings were observed by Mohammadi and Kazemi (2002) and Subramaniam et al. (2006) with increased PPO activity in transgenic wheat heads and pisang-rasthali cultivars, respectively following inoculation with respective Fusarium conidia. Plant defense mechanism is a complex one with the emergence of new pathogenic strains that makes it difficult to study. ...
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The biochemical and metabolic profiles of transgenic banana (Musa spp.) plants developed through RNAi technology for expressing resistance to Fusarium oxysporum f.sp. cubense race 1 were characterized by using gas chromatography coupled to electron impact ionization-time of flight-mass spectrometry (GC/EITOF-MS). A total of twenty-two metabolites were identified and annotated using NIST data library. Several resistance related metabolites such as 13-docosenamide, 9-octadecenamide, 9-octadecene, n-hexadecanoic acid, oleic acid, 1,2-benzenedicarboxylic acid, 2,4,6-decatrienoic acid, 1 bis (2-ethylhexyl) phthalate, methyl abietate, undecanedioic acid, 2-pentadecanone, methyl palmitate and phenols were detected in transgenic plants which were generated to silence two fungal genes viz., ftf1 and/or velvet through RNAi technology. The induction of defense related enzyme activities such as phenylalanine ammonia lyase (PAL), superoxide dismutase (SOD), peroxidase (POD) and polyphenol oxidase (PPO) were also observed. The defense related enzyme activities were higher in transformed plants than untransformed plants. However, these differences did not cause any unintended changes in the growth of transgenic banana plant.
... Different classes of PR-proteins including PR-1, PR-2 (b-1,3-glucanases), PR-3 (chitinases), PR-5 (thaumatin-like protein), and PR-9 (peroxidases) were induced within 6±12 h of inoculation and reached peak levels within 36±48 h after inoculation. Similarly, a 3-fold increase in the polyphenol oxidase (PPO) activity was detected in the resistant wheat cultivars upon inoculation with F. graminearum conidia when compared with the non-inoculated controls (Mohammadi and Kazemi, 2002). ...
Article
Genes encoding pathogenesis‐related (PR‐) proteins isolated from a cDNA library of Fusarium graminearum‐infected wheat spikes of scab‐resistant cultivar ‘Sumai‐3’ were transformed into susceptible spring wheat, ‘Bobwhite’ using a biolistic transformation protocol, with the goal of enhancing levels of resistance against scab. Twenty‐four putative transgenic lines expressing either a single PR‐protein gene or combinations thereof were regenerated. Transgene expression in a majority of these lines (20) was completely silenced in the T1 or T2 generations. Four transgenic wheat lines showed stable inheritance and expression of either a single transgene or transgene combinations up to four generations. One line co‐expressing a chitinase and β‐1,3‐glucanase gene combination, when bioassayed against scab showed a delay in the spread of the infection (type II resistance) under greenhouse conditions. This line and a second transgenic line expressing a rice thaumatin‐like protein gene (tlp) which had moderate resistance to scab in previous greenhouse trials, along with susceptible and resistance checks were evaluated for resistance to scab under field conditions. None of the transgenic lines had resistance to scab in the field under conditions of strong pathogen, suggesting these plants lacked effective resistance to initial infection (type I resistance) under these conditions. As far as is known, this is the first report of field evaluation of transgenic wheat expressing genes for PR‐proteins against disease resistance.
... To a remarkable extent, POX improves a plant's resistance to infection by stimulating lignin production based on reactive oxygen species. The physical barrier created by lignin deposition is more effective at preventing viral infection [72]. Our results match those of other studies [52,73] that considered the ability of different nanoparticles to increase the activity of plant enzymes in response to ROS. ...
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Potato virus Y (PVY) is one of the most harmful phytopathogens. It causes big problems for potatoes and other important crops around the world. Nanoclays have been extensively studied for various biomedical applications. However, reports on their interactions with phytopathogens, particularly viral infections, are still limited. In this study, the protective activity of Egyptian nanoclay (CE) and standard nanoclay (CS) against PVY was evaluated on potato (Solanum tuberosum L.) plants. Their physicochemical and morphological properties were examined with scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), and energy dispersive spectrometer (EDS). SEM and TEM analyses revealed that CE has a spherical and hexagonal structure ranging from 20 to 80 nm in size, while CS has boulder-like and tubular structures of about 320 nm in size. FTIR and EDS showed that both nanoclay types have different functional groups and contain many vital plant nutrients that are necessary for every stage and process of the plant, including development, productivity, and metabolism. Under greenhouse conditions, a 1% nanoclay foliar application enhanced potato growth, reduced disease symptoms, and reduced PVY accumulation levels compared with non-treated plants. Significant increases in levels of antioxidant enzymes (PPO and POX) and considerable decreases in oxidative stress markers (MDA and H2O2) were also reported. Moreover, a significant increase in the transcriptional levels of defense-related genes (PAL-1, PR-5, and CHI-2) was observed. All experiment and analysis results indicate that the CE type is more effective than the CS type against PVY infection. Based on these results, the foliar applications of nanoclay could be used to manage plant viral infections in a way that is both effective and environmentally friendly. To our knowledge, this is the first report of the antiviral activity of the foliar application of nanoclay against PVY infection.
... Enzyme levels in preventive and curative treatments (0.18 and 0.22 µM/g f.wt., respectively) differed significantly from the control (Figure 7). PPO's consumption of reactive oxygen species (ROS) as a substrate has also been linked to the production of lignin within the cell wall, which acts as a protective border against the spread of plant diseases [83]. Figure 7 shows that accumulated CAT was 0.63 M/g f.wt. ...
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Chemical pesticides and fungicides are used extensively, negatively affecting people’s health and the environment. Reducing synthetic pesticides and increasing the efficiency of sustainable food production using plant extracts as natural chemicals is a win–win. Here, we first describe and evaluate an ethanolic extract of Chorisia speciosa for its protective and curative activities against Rhizoctonia solani in greenhouse-grown tomato plants. The results showed that the mycelial growth of R. solani was completely suppressed in vitro by C. speciosa extract (10 µg/mL). Twenty days after fungal inoculation, the results demonstrated that using C. speciosa extract (10 µg/mL) in vivo significantly improved shoot and root growth parameters in protective and curative treatments. Further, the protective and curative treatments decreased the disease index by 26.67% and 53.33%, respectively. C. speciosa-treated tomato plants showed significantly increased antioxidant enzyme production (PPO, CAT, and SOD) and up-regulated PR-1, PR-2, PR-3, PAL, and CHS expression levels compared to untreated plants. According to HPLC examination, the most prevalent phenolic acids or flavonoid components quantities (µg/mL) noticed in C. speciosa extract were 7-OH-flavone (10.36), kaempferol (9.23), p-coumaric acid (8.65), ferulic acid (8.14), caffeic acid (7.59), gallic acid (6.33), and iso-ferulic (5.71). Our findings are the first to demonstrate that a C. speciosa extract can assist plants in combating fungal infestation. Therefore, the data imply that C. speciosa extract, as a natural and renewable product, could be adopted as a long-term approach for regulating plant fungus.
... The bio-control agents activate plant defense genes of the phenylpropanoid pathways, namely encoding peroxidase (POX.), phenylalanine ammonia-lyase (PAL), and polyphenol oxidase (PPO) [76]. They are involved in lignin's biosynthesis, which acts as a protective barrier for pathogen entry into plant tissues [77]. This study proved the activation of defense enzymes in R. solani-challenged black gram with the beneficial yeast isolates I. terricola GRY4 and P. kudriavzevii POY5. ...
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Citation: Bright, J.P.; Karunanadham, K.; Maheshwari, H.S.; Karuppiah, E.A.A.; Thankappan, S.; Nataraj, R.; Pandian, D.; Ameen, F.; Poczai, P.; Sayyed, R.Z. Seed-Borne Probiotic Yeasts Foster Plant Growth and Elicit Health Protection in Black Gram (Vigna mungo L.). Sustainability 2022, 14, 4618. https://doi.
... presumably prevents the spread of plant diseases by forming lignin within the cell wall due to using reactive oxygen species (ROS) as a substrate, thus creating a physical barrier [50]. Similarly, the TMV treatment exhibited the highest levels of accumulated POX (0.46 µmol/g FW) within infected plant tissues. ...
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A series of novel pyrimidine-based derivative compounds were synthesized and evaluated for antiviral activity against Tobacco mosaic virus (TMV). All chemical structures of the prepared compounds were identified and characterized by IR, NMR, and elemental analysis. Under greenhouse conditions, the preliminary bioassays revealed that all compounds exhibited anti-TMV activity ranging from 23.5 % to 90.1% at 50 μg/mL concentration, indicating potential antiviral efficacy. Among the new compounds, the benzylidene derivative 3a was the most potent and demonstrated the highest inhibition effect of 90%, with a significant reduction in the TMV accumulation level of 91.4%. Furthermore, the curative activity of 3a was associated with a considerable decrease in H2O2 and MDA (nonenzymatic oxidative stress markers) compared to the TMV treatment. In addition, significant increases in the transcriptional levels of pathogenesis-related proteins (PR-1, PR-3, PR-4, and PR-5) at 4 and 6 dpi were shown to induce systemic resistance against TMV. Furthermore, molecular docking investigation demonstrated that the benzylidene derivative 3a was strongly lodged in the binding sites of TMV-coat protein at position 2. Consequently, the obtained results suggest that the new 3a compound could be applied as a safe control agent against plant viral infection.
... presumably prevents the spread of plant diseases by forming lignin within the cell wall due to using reactive oxygen species (ROS) as a substrate, thus creating a physical barrier [50]. Similarly, the TMV treatment exhibited the highest levels of accumulated POX (0.46 µmol/g FW) within infected plant tissues. ...
Article
A series of novel pyrimidine-based derivative compounds were synthesized and evaluated for antiviral activity against Tobacco mosaic virus (TMV). All chemical structures of the prepared compounds were identified and characterized by IR, NMR, and elemental analysis. Under greenhouse conditions, the preliminary bioassays revealed that all compounds exhibited anti-TMV activity ranging from 23.5 % to 90.1% at 50 µg/mL concentration, indicating potential antiviral efficacy. Among the new compounds, the benzylidene derivative 3a was the most potent and demonstrated the highest inhibition effect of 90%, with a significant reduction in the TMV accumulation level of 91.4%. Furthermore, the curative activity of 3a was associated with a considerable decrease in H2O2 and MDA (nonenzymatic oxidative stress markers) compared to the TMV treatment. In addition, significant increases in the transcriptional levels of pathogenesis-related proteins (PR-1, PR-3, PR-4, and PR-5) at 4 and 6 dpi were shown to induce systemic resistance against TMV. Furthermore, molecular docking investigation demonstrated that the benzylidene derivative 3a was strongly lodged in the binding sites of TMV-coat protein at position 2. Consequently, the obtained results suggest that the new 3a compound could be applied as a safe control agent against plant viral infection.
... a primary metabolism enzyme of phenylpropanoids seems to play an important role in the synthesis of many secondary defense-related compounds, such as phenols and lignin (Tahsili et al. 2014). Polyphenol oxidase (PPO) (EC 1.10.3.2) another defense-related enzyme is considered to catalyze phenol oxidation to quinones that are harmful to pathogens (Mohammadi and Kazemi 2002). These enzymes are increasingly critical in the direct resistance of plants to pathogenic agents. ...
Article
Full-text available
Plants have a large diversity of metabolites in order to carry out the complicated plant metabolic pathway in a coordinated manner under normal as well as stressful conditions. These metabolites are further subdivided into primary metabolites which are responsible the for main metabolic pathways that are critical for the survival of plants and secondary metabolites which are not necessary for the main metabolic pathway for growth and development but are involved in developing the ability of the plants to interact with the surrounding adverse environment. Plants produce a diversity of secondary metabolites (PSMs) that serve as defense compounds against herbivores and microorganisms. In addition, some PSMs attract animals for pollination and seed dispersal. Pathogens gain entry into host cell, reproduce there and use biological machinery of host plants which is threat to global crop production. Integrated management strategies based upon minimizing population and use of resistant cultivars can address this potential problem. In the developing world, farmers are less likely to adopt these approaches instead they prefer the use of chemical pesticides. Reckless use of chemical pesticides is destroying our ecosystem, which is why ecofriendly alternatives, like plant-based metabolites to control pathogens, must be explored. Studies conducted on different plant metabolites reported that these metabolites can potentially combat plant pathogens. In this study, we also discuss some of the plant secondary metabolites including alkaloids, flavonoids and phenolics, and antioxidant enzymes like peroxidase, polyphenol oxidase, and chitinase.
... Afterwards, mycelial pellets were snap frozen in liquid nitrogen and immediately stored at -80 C till lyophilization using the Lyovac GT2 lyophilizer (SRK-Systemtechnik, Riedstadt, Germany). Lyophilized mycelial samples (100 mg) were processed as described previously (Mohammadi and Kazemi, 2002) and used for analysis of ferrichrome, proteins, and amino acids profiling. ...
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Manipulation of iron bioavailability in the rhizosphere of banana may suppress Fusarium wilt, caused by the notorious soil-borne fungal pathogen, Fusarium oxysporum f. sp. cubense (Foc). However, iron starvation induced by the application of synthetic iron chelators does not effectively suppress Fusarium wilt. It is not clearly known whether Foc can subvert iron chelators and thereby evade iron starvation. This study investigated the production of low molecular weight microbial secondary metabolites, called siderophores, which are known to play an important role in iron scavenging and storage. Cellular amino pools were analysed to determine metabolic changes associated with adaptation iron starvation in Foc. In vitro studies were conducted using iron-deficient growth medium or in growth medium supplemented with a synthetic iron chelator, 2,2′-dipyridyl, to mimic iron starvation. The concentration of extracellular siderophores increased three-fold (p < 0.05) in the absence of iron. Liquid chromatography-mass spectrometry analysis detected the hydroxamate siderophore, ferrichrome, only in the mycelia of iron-starved cultures. Iron-starved cultures also exhibited a reduction in total cellular protein concentration. In contrast, out of the 20 proteinogenic amino acids, only arginine increased (p < 0.05) under iron starvation. Our findings suggest that iron starvation does not cause a remodelling of amino acid metabolism in Foc, except for arginine, which is required for biosynthesis of ornithine, the precursor for siderophore biosynthesis. Our results demonstrate that the biosynthesis of siderophores, particularly ferrichrome, is critical for Foc to evade iron starvation. The empirical evidence whether ferrichrome is essential for Foc survival under iron starvation is suggestive, and requires further research using reverse genetics.
... This result of current work supports the other results about the physical and bio-chemical quality preservation of the navel oranges. PPO is mainly responsible from the oxidation of phenolics into quinones, which protects the tissues from fungal pathogens [Mohammadi and Kazemi 2002]. ...
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Hydrothermal treatments are long known curing methods for the improvement of fruits resistance against storage conditions and for controlling fungal pathogens. The optimal conditions of the hydrothermal treatments significantly vary among species and varieties/cultivars. Present research was conducted to measure the storability effect of hot water dipping (HWD). First of all, three different hydrothermal temperatures (45, 50 and 55°C) tested for 3 different HWD durations (3, 4 and 5 min). Hereafter, main studies were performed with 50°C for 5 min HWD treatment which provided highest performance in preliminary experiments. In this main studies, physical, bio-chemical, physiological and enzymatic characteristics of the fruits were also tested with 20 days interval for 120 days of storage. Results suggested that the HWD treatment reduce respiration rate and enhance the activity of some enzymes, mainly polyphenol oxidase (PPO), peroxidase (POD) and superoxide dismutase (SOD), and helps to preserve physical and bio-chemical quality of ‘Newhall’ navel oranges.
... The bio-control agents activate plant defense genes of the phenylpropanoid pathways, namely encoding peroxidase (POX.), phenylalanine ammonia-lyase (PAL), and polyphenol oxidase (PPO) [76]. They are involved in lignin's biosynthesis, which acts as a protective barrier for pathogen entry into plant tissues [77]. This study proved the activation of defense enzymes in R. solani-challenged black gram with the beneficial yeast isolates I. terricola GRY4 and P. kudriavzevii POY5. ...
... The catalase (CAT) activity was determined based on the rate of H 2 O 2 oxidation (Bergmeyer 1983). The phenol peroxidase (PPO) was estimated using 0.1 M catechol and expressed as ∆OD/min/mg FW (Mohammadi and Kazemi 2002). The phenylalanine ammonia lyase (PAL) activity was estimated using the calibration curve of TCA (trans-cinnamic acid) (Nagarathna et al. 1993). ...
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Endophytes can induce the defence responses and modulates physiological attributes in host plants during pathogen attacks. In the present study, 127 bacterial endophytes (BEs) were isolated from different parts of healthy soybean plant. Among them, two BEs (M-2 and M-4) resulted a significant antagonistic property against Macrophomina phaseolina, causes charcoal rot disease in soybean. The antagonistic potential was evaluated through dual culture plate assay, where M-4 expressed higher antifungal activity than M-2 against M. phaseolina. The M-4 produces cell wall degrading enzymes viz. cellulase (145.71 ± 1.34 μgmL⁻¹), chitinase (0.168 ± 0.0009 unitmL⁻¹) and β,1–3 endoglucanase (162.14 ± 2.5 μgmL⁻¹), which helps in cell wall disintegration of pathogens. Additionally, M-4 also can produce siderophores, indole-3-acetic acid (IAA) (17.03 ± 1.10 μgmL⁻¹) and had a phosphate solubilization potential (19.89 ± 0.26 μgmL⁻¹). Further, GC–MS profiling of M-4 has been carried out to demonstrate the production of lipophilic secondary metabolites which efficiently suppress the M. phaseolina defensive compounds under co-culture conditions. Bio-efficacy study of M-4 strain shown a significant reduction in disease incidence around 60 and 80% in resistant and susceptible varieties of soybean, respectively. The inoculation of M-4 potentially enhances the physiological attributes and triggers various defence responsive enzymes viz. superoxide dismutase (SOD), phenol peroxidase (PPO), peroxidase (PO) and catalase (CAT). The histopathological study also confirmed that M-4 can reduce the persistence of microsclerotia in root and shoot tissue. Conclusively, M-4 revealed as an efficient biocontrol agent that can uses multifaceted measures for charcoal rot disease management, by suppress the M. phaseolina infection and enhance the physiological attributes of soybean. Graphical abstract
... The increased POD enzyme activity in plants as quick reaction to various stresses has been reported by different workers which is considered to scavenge hydrogen peroxide generated in plants on exposure to stress (Torres et al. 2006). Increase in POD activity in the inoculated genotypes having differential level of resistance has been reported by some workers (Purwar et al. 2012;Mohammadi and Kazemi 2012;Singh et al. 2017Singh et al. , 2019Devi et al. 2019). The enzyme POD impart resistance against Karnal bunt pathogen in wheat plants has also been demonstrated by Gogoi et al. (2001). ...
... Zhang et al. (2013) demonstrated that SOD plays a crucial role in resistance to fungal invasion by strengthening cell walls. In addition, PPO has been reported to be involved in preventing the progression of plant diseases by constructing lignin through the consumption of ROS as a substrate within the cell wall, creating a physical barrier (Mohammadi and Kazemi 2002). CAT and POX have been demonstrated to play an imperative role in providing a protective mechanism against oxidative stress following stress exposure. ...
Article
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Root rot and head blight caused by soil-borne fungi are prevalent diseases endanger the global food security. The purpose of this study is to provide insight into the interaction of Fusarium graminearum with two weed extracts, concentrating on growth rate, physiological responses, molecular changes in wheat seedlings and yield parameters. In a pot experiment, wheat grains pre-soaked for 12 h either in distilled water or 25% aqueous weed extracts (purslane or chard) were germinated either in free or F. graminearum pre-inoculated sandy soil. The results revealed that F. graminearum inoculation resulted in reduced growth rate and chlorophyll content in wheat seedlings. However, following the fungal invasion, carotenoids, stress markers (EL, MDA, C = O, OH˙ and H2O2), non-enzymatic antioxidants (ascorbate and flavonoids), osmoregulators (GB, proline and free amino acids), antioxidant enzymes activity (CAT, POX, SOD and PPO) and the expression of some stress-induced genes (CAT, GR and PR4) were substantially increased. Nevertheless, priming of wheat grains with purslane or chard extracts resulted in enhanced growth rate, balanced chlorophyll content, decreased stress symptoms, restoration of the normal level of osmoregulators and antioxidant enzymes activity, as well as down-regulation of stress-induced genes in F. graminearum-infected wheat seedlings, besides improving yield characteristics. However, PR2 gene expression was not affected by either fungal infection or weed priming. In conclusion, natural weed extracts as supplement to chemical antifungals, can be safely employed to increase the growth rate and reconfigure the pathophysiological status of wheat seedlings by reducing the detrimental effects of F. graminearum infection.
... PAL enhances the levels of phenols, phytoalexins, and lignin in fruits, which improve physical barriers against pathogen (Shadle et al. 2003). Enzymes POD and PPO are also important in a way that, both take part in lignin synthesis and help building resistance against various fungal infections (Mohammadi and Kazemi 2002). MeJA inhances these enzyme activities and controls Alternaria alternata in cherry tomato (Chen et al. 2014). ...
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The phytohormone, methyl jasmonate (MeJA) is an important signalling molecule that plays a vital role in regulating plant defense responses as well as antioxidant systems. This is widely studied for postharvest benefits, demonstrating induced plant resistance to various storage stresses (biotic and abiotic). This also influences the production of secondary metabolites and enhances of antioxidant potential. The mode of action and postharvest application of MeJA is still a major area for research. This chapter summarises the contribution of MeJA on ameliorating postharvest quality of fruits with special reference to chilling injury and disease resistance.
... Based on our results, both of polyphenol oxidase and peroxidase enzyme activities were increased at all concentrations of yeast treatment used and fungicide compared with control. This increase may be due to a positive relationship between oxidative activity and resistance developed in plants ( Mohammadi and Kazemi, 2002). Furthermore, the activity of peroxides and polyphenol oxidase increases by using the highest concentration of yeast extract (10 g/L). ...
... Each treatment had three replicates, and the entire experiment was repeated thrice. As per the method described by Mohammadi and Kazemi (2002), PPO activity was estimated, and the absorbance was measured at 398 nm. Guaiacol was used as a substrate to estimate POD activity (El-Neshawy, 2014). ...
Article
Grapes are high nutritional and economic fruit but extremely vulnerable to fungus infections during postharvest storage. Our previous study found that the fungi, Talaromyces rugulosus O1 secretes ochratoxin A (OTA), which inflicts consumer health and economic value. This study found that T. rugulosus O1 has strong pathogenicity and spore germination to produce germ tubes to help it infect grapes. To better understand the molecular interaction between T. rugulosus O1 and grape, RNA sequencing (RNA-seq) was performed, and 5037 genes were identified as differentially expressed genes (DEGs) in grapes after T. rugulosus O1 infection. RNA-seq analysis revealed that T. rugulosus O1 infection, induced complex defense reactions in grapes, including an influx of Ca 2+ , oxidative burst, changes in GSH, plant hormone signal transduction, transcription factor regulation, overexpression of protein kinases, and biosynthesis of plant secondary metabolites. Our study found that the activity of the resistance enzymes in grapes was increased after T. rugulosus O1 infection, which is consistent with the RNA-seq results. Moreover, the accumulation of some antifungal compounds, including flavonoids, phenols, and lignin in grapes, increased grapes' antifungal ability.
... Each treatment had three replicates, and the entire experiment was repeated thrice. As per the method described by Mohammadi and Kazemi (2002), PPO activity was estimated, and the absorbance was measured at 398 nm. Guaiacol was used as a substrate to estimate POD activity (El-Neshawy, 2014). ...
Article
Grapes are high nutritional and economic fruit but extremely vulnerable to fungus infections during postharvest storage. Our previous study found that the fungi, Talaromyces rugulosus O1 secretes ochratoxin A (OTA), which inflicts consumer health and economic value. This study found that T. rugulosus O1 has strong pathogenicity and spore germination to produce germ tubes to help it infect grapes. To better understand the molecular interaction between T. rugulosus O1 and grape, RNA sequencing (RNA-seq) was performed, and 5037 genes were identified as differentially expressed genes (DEGs) in grapes after T. rugulosus O1 infection. RNA-seq analysis revealed that T. rugulosus O1 infection, induced complex defense reactions in grapes, including an influx of Ca2+, oxidative burst, changes in GSH, plant hormone signal transduction, transcription factor regulation, overexpression of protein kinases, and biosynthesis of plant secondary metabolites. Our study found that the activity of the resistance enzymes in grapes was increased after T. rugulosus O1 infection, which is consistent with the RNA-seq results. Moreover, the accumulation of some antifungal compounds, including flavonoids, phenols, and lignin in grapes, increased grapes' antifungal ability.
... The Mohammadi [43] method was used to determine the polyphenol oxidase (PPO) (EC 1.10.3.1) activity. ...
Article
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Lallemantia iberica (L. iberica) is an important dry season medicinal plant. Drought, an important abiotic stress, adversely affects the plant’s metabolism, which can be alleviated by plant growth regulators like brassinolides. A two-year field experiment was conducted in 2017–2018 to determine the effects of three different irrigation regimes and four brassinolide concentrations on the L. iberica biochemical properties. A split-plot based on a completely randomized block design in three replicates was used as an experimental design with the following irrigation regimes: full watering, watering until flowering and watering until branching. These were the main plots, and 0, 0.5, 1 and 1.5 μM brassinolide concentrations were applied as the subplots. The results showed that many antioxidant enzymes and some biochemical parameters were affected by brassinolide treatment. Furthermore, the highest membrane stability and grain yield were produced in full watering treatment in the second year, and these treatments were not affected by brassinolide application. Several concentrations of brassinolide differently affected the studied treatments, and our study suggests that the amelioration of the effects of the drought stress on L. iberica could possibly be achieved through brassinolide-induced elevation of reactive oxygen species (ROS) scavenging defense systems. There is a need for complementary research to prove the effectiveness of foliar application of this growth regulator to improve the growth and yield of L. iberica under water shortage conditions.
... PPO has been used in the synthesis of 3,4-dihydroxy-Lphenylalanine called L-DOPA which is used in the treatment of Parkinson's disease. PPO from fungi and potato play an important role in degradation of the organic contaminants (Hou et al. 2011) and in the formation of pigments (Mohammadi et al. 2002;Bravo and Osorio;2016). It is also implicated in oxygen scavenging (Constabel et al. 2000). ...
Article
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olyphenol oxidases (PPOs) are copper containing enzymes that play a significant role in the browning of fruits and vegetables by catalyzing hydroxylation and oxidation reactions. Currently, PPO gained significant interest of the researchers due to its potential applications in food, paper, pulp and, textile industries and also in pharmaceuticals. The present study was designed to purify and characterized PPO isoforms from fresh banana fruit pulp. The three novel active PPO isoforms (65 kDa, 45 kDa, 28 kDa) were detected by gel filtration chromatography and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The purified isoforms were further studied for the optimum pH (6.5), temperature (40°C), Michaelis constant (Km) and maximum reaction velocity (Vmax). The N-terminal microsequencing was performed on applied biosystem’s pulse liquid protein sequencer and was found to be 28 kDa (Alanine, proline, asparagine, serine, arginine) and 45 kDa (Alanine, proline, isoleucine, alanine, proline). Sequences were aligned by CLUSTALW and showed significant similarity with previously reported banana PPOs.
... The increased POD enzyme activity in plants as quick reaction to various stresses has been reported by different workers which is considered to scavenge hydrogen peroxide generated in plants on exposure to stress (Torres et al. 2006). Increase in POD activity in the inoculated genotypes having differential level of resistance has been reported by some workers (Purwar et al. 2012;Mohammadi and Kazemi 2012;Singh et al. 2017Singh et al. , 2019Devi et al. 2019). The enzyme POD impart resistance against Karnal bunt pathogen in wheat plants has also been demonstrated by Gogoi et al. (2001). ...
Article
Covered smut of barley is an important seed borne disease caused by Ustilago hordei. This disease has been a serious threat and consequently necessitated understanding of barley-smut resistance mechanism. The present study focussed on the biochemical changes in three barley cultivars viz., PL426 (resistant), PL891 (moderately susceptible) and VJM201 (susceptible), during the infection process of covered smut. Dehulled seeds of each of these varieties were artificially inoculated with U. hordei (108 teliospore suspension) prior to germination and the seedling samples were collected at a day interval till 8 days after germination (DAG) for the study. The results revealed a significant increase in antioxidative activities of defense enzymes [peroxidase (POD), phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO)] and total phenolic content in inoculated samples than the uninoculated ones and the increase was more pronounced in resistant line (PL426) than susceptible (VJM201) and moderately susceptible (PL891) ones. PL426 recorded maximum activity of POD (86.70 units min−1 g−1 fw) and PPO (89.30 units min−1 g−1 fw) which leads to the accumulation of more phenols (0.64 mg/g). The biochemical results were further confirmed by observing the effect of aqueous extract of resistant and susceptible varieties on germination of teliospores of U. hordei. Maximum germination inhibition (98%) of teliospores was exhibited by PL426 when 100% concentration was used whereas the inhibition in case of PL891 and VJM201 was only 18% and 2%, respectively at the same concentration. The study has highlighted the changes in the most efficient antioxidative system that could limit the cellular damage caused by U. hordei.
... The susceptible seedlings (sids-1) showed higher activity than that of the resistant one (Giza-168). Similar trend of results was also detected by Mohammadi and Kazemi, (2002). ...
... The phenylpropanoid metabolite pathway is also an important indicator of the basal defense response of plants. Peroxidases (POD) are involved in the cell-wall-building processes such as oxidation of phenolic compounds, suberization, and lignification of host plant cells during the defense reaction against pathogenic agents (Datta & Muthukrishman, 1999;Mohammadi & Kazemi, 2002). ROS production is also an early response in plant-pathogen interaction. ...
... Phenols have a diverse role in stressed plants such as neutralization of reactive oxygen species (ROS), cell wall lignification, anti-nutritional, and unpalatability (Khattab 2007;Bhonwong et al. 2009;Tanase et al. 2019). An increase in phenolic constituents is a common defense response to encounter potential insect/pest infestation in host plants (Mohammadi and Kazemi 2002;Padmaja et al. 2014;Nagrare et al. 2017). Our observation demonstrated that A. soccata infestation upregulates phenolic metabolism in susceptible genotypes by 22.2-32.4% at 15 DAE, and it was not much changed in resistant genotypes. ...
Article
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Shoot fly [Atherigona soccata (Rondani)] is a destructive pest of sorghum at the seedling stage and causes huge losses to grain yield and green fodder. The host-plant resistance mechanism is the best approach to reduce the attack of insects in plants. The damage parameters, morphophysiological traits, and biochemical metabolites had been investigated in the leaves and stem of contrasting sorghum genotypes, viz., resistant (IS18551, ICSV705, ICSV700), moderately resistant (PSC-4), and susceptible (SWARNA and SL-44) at 15 and 21 days after emergence (DAE) against shoot fly infestation.
... Normally, PPO is up-regulated by abiotic and biotic stresses though the responses to stresses varies within PPO gene families by plant species [28]. Overexpression of PPO displayed enhanced resistance to pathogen in wheat, chickpea, tomato, and populus [29][30][31][32][33]. Conversely, down-regulation of PPO resulted in increased disease susceptibility. ...
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Objective: Early leaf spot (ELS) caused by Cercospora arachidicola (Hori) is a serious foliar disease in peanut worldwide, which causes considerable reduction of yield. Identification of resistance genes is important for both conventional and molecular breeding. Few resistance genes have been identified and the mechanism of defense responses to this pathogen remains unknown. Results: We detected several genes involved in disease resistance to ELS through transcriptome analysis. Using RNA-seq technology, one hundred thirty-three differentially expressed genes (DEGs) were identified between resistant and susceptible lines. Among these DEGs, coiled coil-nucleotide binding-leucine rich repeat (NLR) type resistance genes were identified as duplicated R genes on the chromosome B2. Peanut phytoalexin deficient 4 (PAD4) regulator of effector-triggered immunity mediated by NLR resistance proteins and polyphenol oxidase (PPO) genes play important roles in early leaf spot resistance. Our study provides the useful information on plant response to C. arachidicola infection in peanut. The results suggest that a few major genes and several factors mediate the resistance to ELS disease, showing the characteristics of quantitative trait in defense responses.
... The peroxidases promote oxidation of phenols to polyphenol whereas polyphenol oxidases catalyse the oxidation of polyphenols to quinones and lignin's. Therefore, enhanced activity of peroxidase and polyphenol oxidase was recorded in the F. graminearum infected wheat heads of resistance cultivars compared to susceptible ones [99]. In a study to find the effect of seaweed extract on this disease, it was observed that the peroxidase and polyphenol oxidase activity was enhanced in wheat plant showing reduced severity of the phytopathogen [100]. ...
Article
In the scenario of global warming and climate change, an outbreak of new pests and pathogens has become a serious concern owing to the rapid emergence of arms races, their epidemic infection, and the ability to break down host resistance, etc. Fusarium head blight (FHB) is one such evidence that depredates major cereals throughout the world. The symptomatological perplexity and aetiological complexity make this disease very severe, engendering significant losses in the yield. Apart from qualitative and quantitative losses, mycotoxin production solemnly deteriorates the grain quality in addition to life endangerment of humans and animals after consumption of toxified grains above the permissible limit. To minimize this risk, we must be very strategic in designing sustainable management practices constituting cultural, biological, chemical, and host resistance approaches. Even though genetic resistance isthe most effective and environmentally friendly strategy, a huge genetic variation and unstable resistance response limit the holistic deployment of resistance genes in FHB management. Thus, the focus must shift towardsthe editing of susceptible (S) host proteins that are soft targets of newly evolving effector molecules, which ultimately could be exploited to repress the disease development process. Hence, we must understand the pathological, biochemical, and molecular insight of disease development in a nutshell.In the present time,the availability of functional genomics, proteomics, and metabolomics information on host-pathogen interaction in FHB have constructed various networks whichhelped in understanding the events of pathogenesis and coherent host response(s). So now translation of this information for designing of host defense in the form of desirable resistant variety/genotype is the next step. The insightscollected and presented in this review will be aiding understanding the disease and apprise a solution to the multi-faceted problems which are related to FHB resistance in wheat and other cereals to ensure global food safety and food security.
... He added that antioxidants might protect a target by scavenging oxygen-derived species or minimizing the formation of oxygenderived species.Various antioxidants ascorbic acid and its derivatives, glutathione, proline, trehalose, polyols, tocopherols, as well as pigments such as carotenoids and melanins-are present in fungal cells. Mohammadi, and Kazemi, (2002), observed a significant increase in POX specific activity in heads of wheat cultivars following the inoculation with F. graminearum conidia. ...
... Moreover, at the end of storage period, Meet Ghamr cultivar had significant lower decay value ( (Table 1). Recently, Mohammadi and Kazemi (2002) found that polyphenoloxidase oxidize phenols to form more toxic quinines , which directly influence invading pathogens in plant-pathogen interactions. 5-Fruit behaviour during marketing period: Fruit behaviour parameters during marketing period for 4 days at 20±1 o C and 65% RH after removal from cold storage at 1 o C are shown in (Table 3). ...
... Además, la PFO está involucrada en la lignificación de las células vegetales favoreciendo la defensa contra los fitopatógenos (Chen et al., 2014). La enzima POD realiza funciones de oxidación de compuestos fenólicos y lignificación de la pared celular de las plantas (Mohammadi & Kazemi, 2002;Yin et al., 2013). Las peroxidasas por su parte, pueden contribuir a la resistencia inducida ayudando a generar H 2 O 2 que tiene actividad antifúngica frente a diversos fitopatógenos (Peng & Kuc, 1992). ...
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Mexico is the main exporter of tomato worldwide. The use of greenhouses favors the protection and production of vegetables, however; tomato seedlings are sensitive to necrotrophic fungi such as Alternaria sp. The use of fungicides for disease control has been effective, however; the damage to the environment and the appearance of resistant strains leads the investigation of safe alternatives to the use of synthetic fungicides. Chitosan possesses antifungal activity in addition to the ability to activate defense mechanisms in plants. In this study, tomato seedlings were treated with chitosan at different concentrations. The percentage of foliar damage, spore's germination, induction of hydrogen peroxide and enzymatic activity (peroxidase and polyphenoloxidase) was determined. A statistically significant reduction in leaf damage and germination of spores was obtained in plants treated with 0.01% chitosan (up to 80%) compared to the control. The production of H2O2 and the enzymatic activity was induced in treated plants. Thus, the application of chitosan can be a viable alternative for rot control caused by Alternaria sp. in tomato.
... The esterification of total PHE content in the cell wall (lignification) is an effective defence mechanism against pathogen invasion spread (Han et al. 2016). Phenolic compounds are known as nonenzymatic antioxidants which scavenge ROS reducing their possible toxicity (Mohammadi and Kazemi 2002). However, knowledge about physiological and biochemical mechanisms involved in FHB resistance of wheat is limited. ...
Article
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Wheat (Triticum aestivum L.) is leading cereal crop worldwide, but its yield is highly affected due to various diseases, especially Fusarium head blight (FHB), which affects the metabolism of plants. The present study was conducted at the Agricultural Institute Osijek using three winter wheat cultivars (Apache, Bezostaya1, and U1) during 2016/2017. The objectives of our studies were to examine differences in physiological characteristics of FHB resistance among wheat cultivars in the early stage of infection. The FHB incidence and severity was the highest in 'Bezostaya1'. Results suggest that activation of some anti-oxidative enzymes in the first 2 h after Fusarium attack was not efficient to prevent disease. 'Apache', which revealed an average FHB incidence, efficiently activated defence response through phenol metabolism elevation. The most effective defence response trough activation of anti-oxidative enzymes triggered by H2O2 was revealed in 'U1', which resulted in a minimal FHB incidence and disease severity. The obtained results confirm differences in defence strategies of wheat genotypes.
... Higher activity of SOD and reduced decay was then noted for sweet cherry fruit [55]. PPO and POD were previously reported to be responsible for the oxidation of phenolics in plant cells into antimicrobial quinones and protect plants from pathogens [56]. Similar to present results, HWD was previously noted to enhance the activities of PPO and POD in muskmelon fruits [30]. ...
Article
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The current research aimed at studying the possibility of improving the postharvest storability of “Nanfeng” mandarins by hot water dipping (HWD) treatment. The research was conducted in two phases. Firstly, two different temperatures (50 and 55°C) were tested for three different dipping durations (2, 3, and 4 min) on the mandarin fruits, and the best combination was defined for the prevention of weight loss and fruit decay. Next, the optimal treatment (HWD at 50°C for 3 min) was used in further studies to test the effects on the postharvest fruit quality attributes. Regular measurements were performed to determine total soluble solid (TSS) content, titratable acid (TA) content, vitamin C (VC) content, total sugar content, respiration rate, malondialdehyde (MDA) content, and activities of superoxide dismutase (SOD) enzyme, polyphenoloxidase (PPO) enzyme, and peroxidase (POD) enzyme. According to the results obtained, HWD treatment was found to prevent the loss of TSS, TA, and VC contents during the storage period. The HWD-treated fruits were also found to have a lower respiration rate and MDA content as compared with control treatment. Furthermore, HWD treatment significantly enhanced the activities of SOD, POD, and PPO which are known to enhance tolerance to lipid peroxidation and are associated with the fruit protection from injuries and pathogens. Present results also suggest that the activation of the SOD and POD enzymes is highly related to the respiratory activities of the fresh produce. This suggests that the HWD can be used to improve the storability of “Nanfeng” mandarins by maintaining the postharvest physical and biochemical quality.
... FM = fresh matter. n = 10 production of monolignol radicals which are subsequently cross-linked to generate lignin subunits through oxidative coupling during pathogens infection (Huttermann et al. 2001;Mohammadi and Kazemi 2002). The CHI and GLU are often linked with the resistance of plants to either abiotic and biotic stresses and their importance against fungal pathogens is related to their capacity to hydrolyse chitin and β-1,3-glucan, respectively (Gnanamangai et al. 2011;Lattanzio et al. 2006;Wu and Bradford 2003). ...
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Leaf blast, caused by the hemibiotrophic fungus Pyricularia oryzae, is the most important disease affecting rice production worldwide. The present study investigated the potential of using glutamate (Glu) to increase rice resistance to leaf blast. Rice plants (cultivarMetica-1) were non-supplied (−Glu) or supplied (10 mM) (+Glu) with Glu and non-inoculated or inoculated with P. oryzae. Leaf blast severity and the number of lesions per cm2 of leaf were significantly lower by 55 and 50%, respectively, for +Glu plants in comparison to -Glu plants at 96 h after inoculation (hai). The area under the leaf blast progress curve was significantly lower by 70% for +Glu plants in comparison to -Glu plants. For inoculated +Glu plants, the activities of chitinase, β-1-3-glucanase, phenylalanine ammonia-lyase, and polyphenoloxidases as well as the concentrations of total soluble phenolics and lignin-thioglycolic acid derivatives were significantly higher for inoculated +Glu plants in comparison to inoculated -Glu ones. The use of glutamate may become an alternative to be used in the management of rice blast in the context of a sustainable agriculture.
... Similar phenomena was also observed in the studies relevant to it on other fruits such as Peach, Pear and Mango (Liu et al., 2005;Zeng et al., 2006). Production of POD is related with resistance to disease and helpful in phenolic cross link synthesis which involves in connecting biopolymer chains (Mohammadi et al., 2002). This indicates that increase in activity of POD is related to resistance of orange fruit against microorganisms. ...
... These studies are in agreement with the present study, where the preliminary studies showed that HAF significantly reduces decay percentage and the main studies showed that HAF treatment increases the activities of SOD. PPO and POD were previously reported to be responsible for the oxidation of phenolics in plant cells into antimicrobial quinones and protecting plants from pathogens [46]. A similar relationship between decay percentage and PPO and POD activities was noted for muskmelon fruits. ...
Article
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The effects of hot air flow (HAF) treatment on the postharvest storage of ‘Newhall’ navel oranges were investigated in this study. Studies were conducted with two separate sections. First of all, the effects of HAF at 37 °C for 36 h, for 48 h, and for 60 h were tested on fruit decay and weight loss. Thus, the optimal treatment was found as HAF at 37 °C for 48 h based on the fruit decay percentage and weight loss, and further studies were carried out with this treatment. The HAF-treated and control fruits were flowed at 37 °C and 20 °C with relative humidity (RH) of 85–95% for 48 h, respectively. After flowing, fruits of both treatments were individually film-packed, precooled (10–12 °C, 12 h), and stored (6 ± 0.5 °C and 85–90% relative humidity) for 120 days. Regular (0, 15, 30, 45, 60, 90, and 120 days) measurements were carried out for analyzing total soluble solid (TSS) content, titratable acid (TA) content, vitamin C (VC) content, total sugar content, respiration rate, malondialdehyde (MDA) content, and protective enzyme activities. The results indicated that HAF treatment significantly inhibited the MDA content and respiration rate of navel orange fruits after 45 d storage. The superoxide dismutase (SOD) and peroxidase (POD) enzyme activities were enhanced after 60 d storage, while polyphenol oxidase (PPO) enzyme activities were enhanced throughout the storage period. Results suggested that the SOD and POD activities are highly related with respiratory activities and could be enhanced with hot air flow. Meanwhile, HAF treatment maintained high content of TSS, total sugar, TA, and VC.
... In addition to SOD and CAT, polyphenol oxidases (PPO) and peroxidase (POD) also help in the defense mechanism of plants during abiotic stresses. PPO cause polyphenols to oxidize to quinones, which can be important for the plant's defense responses, while PODs are oxidoreductive enzymes that play a crucial role in the process of wall-building, such as suberization, oxidation of phenols, and lignification of host plant cells against biotic and abiotic stresses during the defense reaction (Mohammadi and Kazemi 2002). ...
... When microbes invade plant cells, polyphenol oxidases are involved in the oxidation of polyphenols into quinines (Soliva et al., 2001) [33] . Peroxidases participate in wall building processes, e.g., oxidation of phenols, and the suberization and lignification of host cells during the defence reaction against pathogenic agents (Mohammadi and Kazami, 2002) [24] . These phenol oxidizing enzymes may participate in plant responses to microbes (Reimers et al., 1992;Chen et al., 2000) [29,8] . ...
... Lignin is important for the formation of plant cell walls, which serve as rigid physical barriers during pathogen infection [44]. Additionally, PPO is related to the lignification of host plant cells, and its catalytic products, quinones, are toxic to pathogens [31,45]. Taken together, these results suggest that the phenylpropanoid pathway is actively involved in foxtail millet defense against U. crameri. ...
... In addition, we found that the highest PPO activity occurred in the booting stage. Polyphenol oxidase is a key enzyme that is involved in the lignification of the plant cell wall, wherein it participates in the process of tissue aging [25]. The PCA is an unsupervised method for classifying sample groups based on the inherent similarities or dissimilarities in the chemical composition data without prior knowledge of sample classes [26]. ...
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Barley grass possesses high nutritional value and antioxidant properties. In this study, the phytochemical constituents and antioxidant enzyme activities in six cultivars of barley grass were explored at three developmental stages: tillering, jointing, and booting stages. Total chlorophyll (Chl t) and carotenoid (Car) content, chlorophyll a/b (Chl a/b) ratio, total nitrogen nutrition (TNN), and total soluble protein (TSP) content, and superoxide dismutase (SOD), peroxidase (POD), and polyphenol oxidase (PPO) activities were assayed. The results indicated that the cultivar × development interaction was significant and that developmental stage was the main factor affecting the parameters studied. Cultivars had a negligible effect on these parameters, which varied with the developmental stages. In the tillering stage, Chl t and Car content, TNN, and POD activity achieved their highest value; in the jointing stage, SOD activity peaked; in the booting stage, Chl a/b ratio, TSP content, and PPO activity showed their highest values. TNN showed a negative correlation with TSP. Compared with those in the jointing, Chl t, Car, TSP, TNN content, Chl a/b ratio, and POD and PPO activities increased in the booting and the tillering stages, whereas SOD activity decreased. The differences in phytochemical constituents and antioxidant enzyme activities in barley grass were mainly correlated with the developmental stages. The aim of this study was to demonstrate the influence of developmental stages of barley grass on its phytochemical profile and antioxidant activities. Our results will help understand the mechanism of action of barley grass and provide theoretical support for the therapeutic application of barley grass.
Research
Bakanae of rice caused by Fusarium fujikuroi has become an important disease in major rice production regions worldwide. Twenty-nine isolates of F. fujikuroi were differentiated based on produced pigments, gibberellic acid (GA3), molecular characteristics and correlated with bakanae disease symptoms of rice seedling. All isolates of F. fujikuroi produced pigments except six isolates. Also, all isolates differed in the production of gibberellic acid. The isolate FI 12 was the highest produced for GA 3 and disease severity index. Molecular analysis showed that nine ISJ primers produced a total of 809 amplified bands. Current results indicated that the Fusarium isolates were clustered largely based on location and/or severity of isolates and level of GA 3 production. The molecular results obtained proved the existence of high levels of genetic variation and high-resolution power of ISJ marker in detecting Fusarium molecular diversity. The differential behavior of bakanae pathogen in resistant and susceptible rice genotypes during infection was studied. Under greenhouse condition, Giza 177 was highly susceptible to rice genotypes while Giza 179 and Giza 178 were moderately resistant. Biochemical changes such as antioxidant enzymes and hydrogen peroxide (H2O2) was observed in rice seedling after 7, 15 and 21 days from inoculation. Enzymes activities were increased in Giza 179 and Giza 178 genotypes, but in H2O2 content was decreasing. Under field conditions, all genotypes showed increased chlorophyll content, number of tillers/hills and means of panicle length/10 healthy plants compared with infected plants. Giza 179 showed the highest grain yield.
Article
Penicillium digitatum and Penicillium italicum are potentially important post-harvest pathogens of citrus fruit causing huge economic loss. In this study salicylic acid (SA) and Cinnamomum verum were tested to control the infection of P. digitatum (green mold) and P. italicum (blue mold) as an alternative to chemical control. In an in vitro assay methanolic extracts of five plants were tested for antifungal activity where C. verum exhibited the highest colony growth inhibition 74.6 and 76.4 % of green and blue mold respectively. Moreover, during In Planta assay the combination of C. verum and SA produced the lowest disease incidence (20 and 33.3%) and severity (13.1 and 6.1%) of green and blue mold respectively compared to stand-alone treatments without affecting the fruit quality considerably. Furthermore, an upsurge in the the activity of polyphenol oxidase (PPO), peroxidase (POD), and phenylalanine ammonia lyase (PAL) encoding genes of citrus fruit was recorded during transcriptional profiling. The highest gene expression was recorded in fruit treated with C. verum and SA in combination compared to healthy control. Similar results were observed during quantification of corresponding gene products. This unveils the fact that the enhanced expression of defense-linked genes might be associated with the disease suppression. Conclusively, our findings indicate that C. verum and SA in combination can suppress green and blue mold of Citrus by modulating the expression of defense-linked genes. The combined use of plant extracts and resistance inducers is a safer alternate to chemicals to suppress green and blue mold during storage.
Preprint
Longan (Dimocarpus longan) is a subtropical fruit best known for its nutritious fruit and has been regarded as a precious tonic and traditional medicine since ancient times. High-quality chromosome-scale genome assembly is valuable for functional genomic study and genetic improvement of longan. Here, we report a chromosome-level reference genome sequence for longan cultivar JDB with an assembled genome of 455.5 Mb in size anchored to fifteen chromosomes, representing a significant improvement of contiguity (contig N50=12.1 Mb, scaffold N50= 29.5 Mb) over a previous draft assembly. A total of 40,420 protein-coding genes were predicted in D. longan genome. Synteny analysis suggests longan shares the widespread gamma event with core eudicots, but has no other whole genome duplications. Comparative genomics showed that D. longan genome experienced significant expansions of gene families related to phenylpropanoid biosynthesis and UDP-glucosyltransferase. Deep genome sequencing analysis of 87 longan accessions identified longan biogeography as a major contributing factor for genetic diversity, and revealed a clear population admixture and introgression among cultivars of different geographic origins, postulating a likely migration trajectory of longan overall confirmed by existing historical records. The chromosome-level reference genome assembly, annotation and population genetic resource for D. longan will facilitate the molecular studies and breeding of desirable longan cultivars in the future.
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Different Palestinian plant extracts were bio-assessed against the fungi Ustilago tritici and Ustilago nuda Moreover, they were tested for their potentiality in inducing resistance pathways on four different cultivars of wheat and barley. Measuring two common enzymes indicator such as guaiacol Peroxidase (POX) and Polyphenol oxidase (PPO) expressed in plants after being induced physically or chemically. In vitro antifungal activity of the plant extracts on the fungal growth was carried out. Results showed that 70% of the plant extracts have antifungal activity against Ustilago tritici and Ustilago nuda. Coridothyme extracts was ranked first with 61% growth inhibition among all. Results also revealed that some plant extracts have significantly increased the impact on POX and/ or PPO compared to the control among all wheat and barley cultivars tested. Oregano, Clove or Lavender and Pomegranate, Achillce or Cammomile oil have effective induction for resistance indicator enzymes in wheat and barley, respectively. This study, investigated the role of endogenous Palestinian plant extracts in inducing wheat and barley resistance systems against loose smut disease. In-order to alternate chemical control with fungicides.
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