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Phylloplane microbes have been studied as strategic tools in management against plant pathogens. Non-pathogenic bacteria and fungi have been applied as crop protectants against various plant diseases. The present study aimed at evaluating the potentiality of Aspergillus niger spores in altering the activity of four key enzymes related to defense in tomato. The experiment was designed such that two groups of 50 tomato plants were considered: group 1 – sprayed with autoclaved distilled water (control) and group 2 – sprayed with A. niger spores. Spraying was carried out under aseptic conditions. The experimental parameters included analysis of the activity of peroxidase (POX), polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL) and tyrosine ammonia lyase (TAL) as well as expression of POX and PPO isoforms. The results demonstrated an inductive effect of A. niger on the activity of POX, PPO, PAL and TAL. Enhanced expression of POX and PPO isoforms was also observed. The results indicated that A. niger can be considered probiotic for the management of tomato against its phytopathogens.

BACKGROUND Button mushrooms with completely white appearance are popular with consumers. However, button mushrooms are susceptible to infection with Pseudomonas tolaasii (P. tolaasii), which results in browning. This study evaluates the effects of ultraviolet-C (UV-C) treatment on the inactivation of P. tolaasii in vitro and in vivo and on the physiological and chemical changes of button mushrooms during storage for 21 days at 4 °C. RESULTS UV-C doses of 0.5-9.0 kJ m-2 resulted in 3.91-6.26 log CFU mL-1 reduction of P. tolaasii populations in vitro, and UV-C treatment reduced P. tolaasii populations inoculated on mushroom cap surfaces and browning severity. Moreover, P. tolaasii increased polyphenol oxidase (PPO) activity, and decreased phenylalanine ammonia-lyase (PAL) activity, the accumulation of phenolics and contents of brown melanin precursors, including γ-L-glutaminyl-4-hydroxybenzene (GHB), γ-L-glutaminyl-3,4-dihydroxybenzene (GDHB), and tyrosine in button mushrooms. UV-C treatment was found to reduce the negative changes due to P. tolaasii infection. CONCLUSION These results indicated that the application of UV-C treatment inhibited browning, inactivated P. tolaasii and reduced P. tolaasii - associated chemical and enzymatic changes of button mushrooms. This article is protected by copyright. All rights reserved.

Silicon (Si) is very effective in the amelioration of heavy metal (HM) stress in different crop plants. This investigation was conducted to assess the protective role of Si in modulating aluminium (Al) uptake in 21 days old common buckwheat (Fagopyrum esculentum M.) plants. Exogenous Si (0.5 and 1 mM) treatments were used to study the effect on chlorophyll contents, anthocyanins, total phenolic content (TPC), total flavonoid content (TFC) and defence enzymes (phenylalanine ammonialyase (PAL), tyrosine ammonia lyase (TAL) and polyphenol oxidase (PPO) activities) against Al (0.2 and 0.4 mM) treatments. Results indicated that Al phytotoxicity negatively affected the above mentioned parameters while as Si application markedly reduced the phytotoxicity caused by Al3+ ions by improving their contents and increasing defense enzyme activities. Si thus alleviates phytotoxicity caused by Al ions and also promotes the production of phenolic and flavonoid compounds by stimulating the phenylpropanoid pathway. The present study revealed that exogenous Si application influenced the phenylpropanoid pathway in common buckwheat irrespective of being an Al tolerant plant thereby decreasing the oxidative damage and enhancing free radical scavenging activity by increasing the production of phenolic and flavonoid compounds under Al stress.

Pathogens associated with onion seeds cause serious problems by decreasing the percentage of germinated seeds and impeding the growth of germinated seedlings leading to pre- and post-emergence damping-off. Two fungal isolates, Aspergillus niger and Fusarium oxysporum, associated with commercial onion seeds were isolated, identified, and tested for their pathogenicity. Different concentrations of hydrogen peroxide (H2O2)-based compounds [peroxyacetic acid (PAA), potassium bicarbonate (PB)] alone or combined with microwave treatment for eight seconds (M8) or ten seconds (M10) were also evaluated against pre- and post-emergence damping-off caused by A. niger and F. oxysporum, as well as their impact on morphological and physiological traits of onion seedlings. Our results revealed that H2O2-based compounds and/or microwave treatments significantly increased the germination percentage and vigor index of onion seeds and decreased the disease incidence of damping-off. The highest germination percentages were achieved when onion seeds without artificial fungal infection were soaked in PPA1 (95.5%), M8 + PPA2 (95%) and PB_2 (93%), compared with their control (85.5%). The three treatments also significantly increased the vigor index of the onion seedlings from 804 to 2311, 2157, and 1916, respectively. Treatment of M10 + PAA_2 significantly reduced disease incidences of pre-emergence damping-off in onion cultivar Giza_20 from 35 and 30 to 18.5 and 9.6 caused by A. niger and F. oxysporum, respectively. All tested treatments were able to induce onion resistance by increasing the concentrations of salicylic acid, phenolic compounds, phenylalanine ammonia-lyase, and polyphenol oxidase. The tested treatments seem to regulate H2O2 in infected onion seedlings by increasing the level of catalase, ascorbate peroxidase, and guaiacol peroxidase.

The effects of a commercial Ascophyllum seaweed extract (ASWE) on the growth parameters of sweet pepper plants were studied under grow box home garden conditions in the Caribbean. Grow box cultivation of vegetables in the backyard is very popular in Trinidad and Tobago and the wider Caribbean region. The use of synthetic chemicals should be avoided under home conditions due to the underlying hazards and for biosafety reasons. The application of ASWE at the rate of 0.5% as a foliar spray in sweet pepper plants under grow box home garden conditions improved the plant growth parameters, increased the fruit number, and also enhanced the shelf life of the harvested sweet pepper fruits. Soil drenching of ASWE to plants was less effective compared to foliar application. ASWE foliar spray also reduced the intensity of diseases and pests in plants and further promoted the prevalence of natural enemies. The spraying of ASWE significantly increased the biochemical constituents such as chlorophyll content, reducing sugars, phenol, and amino acids compared to the water control. The activity of the defense-related enzymes (chitinase, β-1,3 glucanase, peroxidase, polyphenol oxidase, phenylalanine ammonia-lyase), and phenolic content was significantly greater in sweet pepper plants treated with ASWE treatment compared to the control. Seed treatment by priming in 0.5% ASWE significantly increased the germination percentage, shoot, and root length of seedlings. The positive effects of ASWE might be attributed to the chemical makeup, native to the seaweed extract, which is believed to contain several organic components, including dissolved nutrients and growth-promoting and diverse functional organic molecules that can induce multiple growth effects in plants. This study demonstrates that ASWE can be readily used under home garden conditions as this would be very conservative to the environment as well as promote the system of organic cultivation.

Corn (Zea mays) is one of the most widely spread cereals in the world. However, in the Far North Region of Cameroon, the incidence of some maize diseases progress because of farming practices and climate change (rainfall). This work aims to evaluate effect and resistance stimulation of neem extract and Mancozeb fungicide on Brown Spot (PBS) and Stalk Rot (PSR) diseases of corn due to Physoderma maydis in field condition. The experimental design was a two-factor split-plot. The treatments were a combination of Control (T), Mancozeb (Mz) at the concentration of 6g/L and aqueous extract of neem seeds (AENS) at the concentration of 50g/L with CMS 9015 and CMS 8704 varieties. Incidence, severity, rainfall, Area Under Disease Progress Curve (AUIPC, AUSiPC) were recorded. Phenol and protein rates, enzymatic activity of Polyphenol oxidase (PPO), peroxidase (POX) and glucanase were carried out. Stalk length and yield were evaluated. Incidence and severity of Physoderma Brown Spot (PBS) and Physoderma Stalk Rot (PSR) increased with time and environmental conditions (rainfall). The highest disease incidence was observed in the control treatments with both diseases, 52.39 and 37.67 % respectively for Brown Spot and Stalk Rot in CMS8704 variety and lower with AENS, 13.5 and 36.01%. AENS reduced PBS incidence and severity by 23.1 and 19.9 %, respectively and Mz by 9.3 and 18.1 %. The AUIPC and AUSiPC of PBS and PSR remained lower with AENS treatment during the growing season and higher with the other treatments. The highest phenol and proteins rates (8.81 and 25.1 mg/g/FM) were recorded for the AENS treatment in CMS9015 and CMS8704 variety, respectively. Enzymatic activity was more enhanced in CMS8704 variety with AENS. 4.22 A470/min/g, 1.55 A470/min/g and 1.15 µmole/min /g were recorded respectively for PPO, POX, and Glucane activities. Stalk length was higher in AENS and Mancozeb treatments with variety CMS8704 (125.13 and 123 cm respectively). A yield increase of 7.44% was obtained in the AENS treatment. The combination or not of aqueous neem extract and CMS8704 could be used in the integrated control of PBS and PSR of maize

Priming of seeds is a simple and low-cost method in agriculture that improves plant growth, crop yield, and manages pathogens. The current study was carried out to determine SA seed priming effect on susceptibility and resistance of two wheat cultivars (Falat and Sumai3) to Fusarium graminearum at the seedling stage. Both the 1 and 2 mM SA-primed seeds showed a higher level of resistance against F. graminearum, as a lower disease incidence of 53% and 63% in the Falat and 48% and 76% in the Sumai3 was observed compared to the F. graminearum-inoculated water-primed control. Along with the increased resistance induced by SA priming, we observed increased activities of superoxide dismutase (SOD), polyphenol oxidase (PPO), peroxidases (POX) and phenylalanine ammonia lyase (PAL), in addition to higher mRNA accumulation of PAL, β-1,3-glucanase (GLU-2), chitinase (CHI), cytochrome P450 (CYP), and pleiotropic drug resistance (PDR) genes compared to the water-primed F. graminearum-inoculated control. Therefore, SA seed priming is a suitable alternative to manage the incidence of F. graminearum infection by triggering plant defense responses.

Mucuna pruriens (L.) DC var. pruriens is the natural source for L-DOPA, precursor of the neurotransmitter dopamine, used widely in the treatment of Parkinson's disease. However, L-DOPA synthesis in plants is mediated either by Catecholamine (CA) pathway or alternate pathway catalyzed by Cytochrome P450 (CYP450) class of enzymes. Interestingly, the CA pathway itself can be initiated either by tyrosine hydroxylase (TH) or polyphenol oxidase (PPO). The CA pathway mediated synthesis of L-DOPA has not yet been proved in M. pruriens albeit strong indications. Therefore, the present investigation is focused on metabolite analysis of major intermediates of CA pathway up to the formation of dopamine and expression analysis of the selected genes, in different tissues and callus cultures. The four major intermediates, L-tyrosine, tyramine, L-DOPA and dopamine, were detected using NMR spectroscopy and quantified by HPLC in the callus cultures and in different tissues of the field plant, respectively. The various stages of leaf tissue were also analyzed for metabolite profiling. The relative amount of intermediates detected during the ontogeny of leaf indicates that PPO mediated conversion of L-tyrosine to dopamine through L-DOPA is relatively higher compared to dopamine production from tyramine. Among the two possible enzymes, activity of PPO was 6.5-fold more than TH in metabolically active young leaves compared to intermediate leaves. The gene expression profiles comprising upstream genes of L-tyrosine synthesis and downstream up to dopamine synthesis shows strong correlation with L-DOPA synthesis. The study validates CA pathway mediated synthesis of L-DOPA with PPO as candidate enzyme, in M. pruriens.

The current study was performed to evaluate the potential of two plant extracts (from Nigella sativa L. seeds and Clerodendrum inerme L. leaves) and salicylic acid to induce systemic resistance (ISR) against Potato virus Y (PVY) in potato plants. Ultrastructure investigations using the transmission electron microscope (TEM) exhibited Pinwheels and Ga-Golgi apparatus in the infected plants. Flexuous filaments particles (with a model length of 730×13 nm) were observed in the infected sap using TEM investigation. RT-PCR technique revealed a band- sized at 610 bp in the infected samples with PVY. The infection with PVY was confirmed morphologically and histologically. The most effective treatment for induction of ISR was Nigella sativa L., since the highest reduction of virus infection and the lowest inhibition rate (34.7 and 61.7, respectively), were recorded in plants treated with this plant extract and salicylic acid. Peroxidase (POD) activities were 59.7and 37.7 and polyphenol oxidase (PPO) activities were 23.7and 21.0 after 1- and 2-weeks of Nigella sativa L. treatment, respectively.On the other hand, salicylic acid had the lowest effect on decreasing PVY infection rate and virus inhibition, resulting in of ISR in potato plants. Taken together, the extracts of Nigella sativa and Clerodendrum inerme as well as salicylic acid could be used to control PVY infection. A further study is needed to evaluate these materials under field conditions.

Purpose Catharanthus roseus is a vital medicinal plant due to its content of alkaloids vincristine and vinblastine which are known to have a special interest in the pharmaceutical industries. Little is known about the effects of jasmonic acid (JA) on C. roseus plants grown under saline conditions. Materials Pots experiment was conducted to explore the impacts of four treatments of JA (0, 0.50, 1.0, and 1.50 mM) on the growth of C. roseus plants which were irrigated with saline (EC = 5.27 dS m−1) or tap water (EC = 0.53 dS m−1). Results The growth of C. roseus plants was reduced due to the irrigation with saline water; on the other hand, the salinity induced the accumulation of alkaloids. Salt stress induced a 41% increase in the alkaloid yield of C. roseus plants compared to the control plants irrigated with fresh water. Some defense mechanisms including: osmoregulation, ion compartmentalization, and antioxidants accumulation were activated in C. roseus plants upon salt stress. The foliar application of JA to the C. roseus plants increased the growth parameters and mitigated the salt stress; moreover, it enhanced nutrients uptake. Spraying of C. roseus plants with JA significantly enhanced the biosynthesis of compatible solutes and decreased the activity of pyrogallol peroxidase (PPX) and polyphenol oxidase (PPO). Foliar application of JA increased the alkaloids yield of C. roseus plants. Conclusion JA reduced the negative effects of salt stress in C. roseus plants through increasing osmoregulation compounds and regulating the activity of antioxidant enzymes. Spraying of C. roseus with JA could be used as a sustainable strategy for promotion its medicinal property by augmenting secondary metabolites production.

Genetic resistance is the main strategy to control Fusarium wilt in common bean. Despite this, few studies have focused on defense mechanisms involved in bean resistance to Fusarium oxysporum f. sp. phaseoli (Fop). Thus, the present study aimed to investigate the changes in xylem morphology and involvement of phenylpropanoid compounds and their biosynthetic enzymes in bean resistance against Fop. Uirapuru and UFSC-01 genotypes characterized, respectively, as susceptible and resistant were used. In roots and hypocotyls, guaiacol peroxidase (GPX), phenylalanine ammonia-lyase (PAL), and polyphenol oxidase (PPO) activities were determined at 0, 1, 2, 3, 4, 5, and 6 days after inoculation (dai), and flavonoids, total phenolics, and lignin content were quantified at 0, 3, and 6 dai. Cross sections of taproots and hypocotyls were examined under epifluorescence (at 1, 3, and 6 dai) and transmission electron (at 6 dai) microscopic to analyze the morphology of xylem cell walls. Overall, there was an increase in the activity of all studied enzymes in resistant bean plants, mainly during advanced colonization stages. Modifications in xylem morphology were more intense in roots of resistant genotype resulting in an increase of occluded cells, organelles, and cell wall strengthening. This study provides evidence that bean resistance is associated with increased phenylpropanoid enzymatic activity and cell wall reinforcement of some xylem cells.

In order to study the effect of phenylalanine-functionalized carbon nanotubes (f-MWCNT) on the parameters of callus induction and variations in antioxidant enzymes activity as well as secondary metabolites biosynthesis of basil (Ocimum basilicum L.), optimum concentrations of functionalized and pristine carbon nanotubes were applied in optimized hormonal culture. Basil hypocotyl fragments were cultured in completely sterile conditions in culture medium with 0, 50, 100 and 200 mg/L concentrations of functionalized and pristine carbon nanotubes. The callus induction frequency Cif and dry matter content (DMC), catalase, polyphenol oxidase (PPO), peroxidase (POD), and L-phenylalanine ammonia-lyase activity were also measured in the present study. Additionally, the content of total phenolics and flavonoids, as well as individual phenolic acids, was quantified. Functionalized MWCNTs exhibited the highest callus induction as well as fresh and dry weight in the concentration, 100 mg/L of f-MWCNT. No significant differences in dry matter content between the levels was observed in this study. Catalase activity was also increased with increasing functionalized and non-functionalized carbon nanotube concentration. The highest activity of PPO, POD, and individual phenolic compounds were observed at 200 mg/L of f-MWCNT, 50 mg/L of pristine MWCNT and 100 mg/L of MWCNT, respectively.

Forty two groundnut (Arachis hypogaea) cultivars were screened for resistance to Phaeoisariopsispersonata under glasshouse conditions. Among them, two germplasms (VG19561 and VG19654) were found to have resistance against late leaf spot. Biochemical parameters such as, phenylalanine ammonia-lyase, peroxidase, polyphenol oxidase and total phenols were estimated among the resistant germplasms and susceptible check, VRI2. biochemical analysis revealed the increased activities of the enzymes viz., phenylalanine ammonia lyase, peroxidase, polyphenol oxidase, and phenolics in the resistant germplasms viz., VG19561 and VG19654 than the susceptible check, VRI 2. View Article DOI: 10.47856/ijaast.2021.v08i7.001

Endophytic microorganisms is a major constrain to the establishment and growth of tissue culture plants. We report the use of copper sulfate (CuSO4.5H2O) to eliminate the endophytic bacteria in Philodendron selloum in vitro cultures. Contaminated shoots were cultured onto Murashige and Skoog (MS) medium containing 5 mg/L BA and supplemented with different concentrations of copper sulfate at 0, 35, 70 and 140 mg/L for 6 weeks. Copper sulfate at 70 mg/L completely eliminated the endogenous bacteria without decline in plant growth. However, 35 mg/L copper sulfate was optimal for maximum shoot multiplication (25), survival percentage (100%) and growth of plants. Antioxidant enzymes activity of catalase, peroxidases, and polyphenol oxidase were increased because of copper sulfate treatments. Conversely, electrolyte leakage was decreased at low copper sulfate (≤70 mg/L). Randomly amplified polymorphic DNA (RAPD) analysis revealed that plantlets exposed to different levels of copper sulfate were not genetically different from control plants.

Enzymatic browning is associated with the action of polyphenol oxidases (PPO) and peroxidases (POD). The products of these enzymes cause undesirable changes of color and flavor of processed eggplant products. The present study aimed to evaluate kinetic properties and thermodynamics parameters of PPO and POD activities for controlling this undesirable process in extract from of violet eggplant. The effect of heat treatment on polyphenol oxidase and peroxidase activities in violet eggplant were studied over a range of 30 to 80 °C. T1/2-values of enzymatic activities are between 6.15 ± 0.03 and 13,27 ± 0,04 min at 80 °C, they decreased with increasing temperature, indicating a difference thermostability of each enzyme. D- and k-values decreased and increased, respectively, with increasing temperature, indicating faster of these enzymes inactivation at higher temperatures. Results suggested that polyphenol oxydase and peroxidase were relatively thermostable enzymes with a Z-value which from 50.25 and from 88.33 °C and Ea of 41.21 and of 27.78 kJmol-1. Thermodynamic parameters were also calculated. The Gibbs free energy ΔG values range from 43.24 ± 0,03 to 91.45 ± 0,01 kJ/mol. These kinetic data can be used to predict prevention of browning in the violet eggplant (Solanum melongena L.) by thermal inactivation of enzymes.

The ability of various Streptomyces isolates obtained from soil to induce systemic resistance in tomato (Solanum lycopersicum cv. Supra) plant against Tomato mosaic virus (ToMV) was characterized in current study. Importantly, of nine Streptomyces isolates tested herein, the culture filtrate (CF) of one isolate, designated as Streptomyces ovatisporus LC597360, was the most effective. It exhibited 93.9% biocontrol efficacy and induced a significant decrease (17.6 ± 0.8%) of symptoms severity compared with infected control plants. These finding were confirmed using I-ELISA showing that ToMV concentration was significantly reduced in plants treated with S. ovatisporus LC597360 CF as compared with plants inoculated with ToMV. Moreover, treatment with CF of S. ovatisporus LC597360 not only increased activity of defense-related enzymes such as ascorbate oxidase, catalase, peroxidase, and polyphenol oxidase, but also induced plant growth promotion. The present study is the first one that demonstrates the potential of S. ovatisporus LC597360 in biocontrol of ToMV and investigated its antiviral mechanisms.

Fusarium wilt caused by Fusarium oxysporum (Fo) is the maximum critical soil borne diseases of chickpea in Egypt and many other countries in the world. Sixteen F. oxysporum(Fo) isolates were collected from 9 Governorates in Egypt isolated from wilted chickpea plants. Identification of these isolates was achieved by variation in morphological characters i.e., growth rate, growth habits, pigments, sporulation, and the morphological identifications were further confirmed by molecular method using specific ITS primers. Virulence of these isolates was classified as high virulence (Fo7, Fo8 and Fo10), moderate (Fo2, Fo3, Fo6, Fo9, Fo11, Fo13, Fo14, Fo15 and Fo16) and low (Fo1, Fo4, Fo5, Fo12). Host response of chickpea cultivars infected with Fo7 showed a moderate resistance (Giza-2 and Giza-531) and susceptible ones (Giza-195, Giza-1 and Giza-88). Mechanism underline induce disease resistance revealed that resistant chickpea cultivars contained high activities peroxidase, polyphenol oxidase, catalase, Phenylalanine ammonia lyase and Phenolic compounds than susceptible cultivars.

The synergistic effects of carboxymethylcellulose (CMC) combined with Cryptococcus laurentii FRUC DJ1 were studied on controlling green mould resulting from Penicillium digitatum in grapefruit fruit. The results indicate that both C. laurentii and the CMC treatment suppressed P. digitatum conidia germination. In addition, C. laurentii growth in vitro was not affected by low CMC concentrations, nevertheless, the biofilm of C. laurentii was enhanced. Compared with the control fruit, the grapefruit had a lower green mould in all treatments. Significantly synergistic effects were caused by combining C. laurentii and CMC on minimum decay incidence and lesion diameter. Combined treatment induced defence enzyme activities, including chitinase, β-1,3-glucanase, peroxidase, polyphenol oxidase, and phenylalanine ammonia-lyase, together with disease tolerance-associated total phenol. Also, this combination inhibited the pathogen growth by adhered to the hyphae and reduced its infection in fruit wounds. Moreover, the commercial quality parameters in the combined treatment of C. laurentii and CMC, including weight loss, total soluble solids, ascorbic acid, and titratable acidity, were superior to single treatment. The combination of C. laurentii and CMC can not only control postharvest decay but also maintain fruit qualities. Thus, it can be used in grapefruit for commercial purposes.

Polyphenol oxidase is the popular enzyme involved in fruit-vegetable browning and melanin synthesis. In the present paper, L-3-phenyllactic acid, a natural bacteriostatic substance, was investigated as an inhibitor of polyphenol oxidase. The results were demonstrated that the residual enzyme activity of polyphenol oxidase decreased gradually with the increase of the concentration of L-3-phenyllactic acid. The L and ΔE values of the reaction system increased gradually. The reversible mixed-type inhibition mode of L-3-phenyllactic acid was determined by Lineweaver Burk plot. At the same time, the results of fluorescence quenching demonstrated that L-3-phenyllactic acid was a quencher of polyphenol oxidase, and the molecular docking study provided the binding mode of L-3-phenyllactic acid and polyphenol oxidase at the molecular level. L-3-phenyllactic acid decreased the activity of polyphenol oxidase and browning of fresh-cut Agaricus Bosporus. This research first studied the inhibitory effect of L-3-phenyllactic acid on the activity of polyphenol oxidase, and would provide a theoretical foundation for the use of L-3-phenyllactic acid as anti-polyphenol oxidase agents.

Late blight is caused by Phytopthora infestans (Mont.) de Bary which establishes quickly in Solanum esculentum L. (tomato); as a result, it makes the pathogen one of the most devastating plant diseases across the world. The control of late blight is difficult because P. infestans has advanced and complex enzymes and effecter molecules coded by avirulence genes. As such, a study was carried out at the University of Zimbabwe, Department of Plant Production Sciences and Technologies, between August 2018 and May 2019 to evaluate the efficacy of Moringa oleifera Lour. (moringa), Eucalyptus nigra R.T. Baker (gumtree), and Lantana camara L. (sensu lato) (lantana) extracts as biofungicides on late blight development on S. esculentum. The effect of acetone, ethyl acetate, and water extracts of M. oleifera, E. nigra, and L. camara on percent inhibition and radial growth were evaluated in the laboratory. In addition, the efficacy of different extract concentrations of M. oleifera, E. nigra, and L. camara L. on defence enzymes, disease incidence, disease severity, and yield parameters of S. esculentum were assessed in the in vivo experiment. Increasing concentration of the botanical extracts significantly ( p ≤ 0.05 ) reduced radial growth and increased percent inhibition of P. infestans. In addition, increasing botanical extract concentration significantly ( p ≤ 0.05 ) increased peroxidase (PОD), phenylalanine ammonia lyse (PAL), and polyphenol oxidase (PPO) activity. Disease incidence and severity were significantly ( p ≤ 0.05 ) reduced as the concentration of the botanical extracts increased. Similarly, marketable and total yield significantly ( p ≤ 0.05 ) increased with increase in the botanical extract concentration. Gas chromatography mass spectrometry (GCMS) revealed the presence of furfural, 5-methyl-4- (trifluoromethyl) pyrido, dodecanamide, cyclopentasiloxane, and decamethyl. From the research, it can be concluded that M. oleifera ethyl acetate, E. nigra ethyl acetate, and L. camara water extracts contain antifungal compounds and can be used as biofungicides in late blight management.

The fungal pathogen, Alternaria alternata is responsible for causing leaf spot disease in many plants, including chili pepper. Zinc (Zn) an essential micronutrient for plant growth, also increases resistance in plants against diseases, and also acts as an antifungal agent. Here, in vitro effects of ZnSO4 on the propagation of A. alternata were investigated, and also in vivo, the effect of foliar application of ZnSO4 was investigated in chili pepper plants under disease stress. In vitro, ZnSO4 inhibited fungal growth in a dose-dependent manner, with complete inhibition being observed at the concentration of 8.50 mM. Hyphae and conidial damage were observed along with abnormal activity of antioxidant enzymes, Fourier-transform infrared spectroscopy confirmed the major changes in the protein structure of the fungal biomass after Zn accumulation. In vivo, pathogen infection caused the highest leaf spot disease incidence, and cumulative disease index, which resulted in a significant reduction in the plant’s growth (length and biomass), and physiochemical traits (photosynthetic pigment, activity of catalase, peroxidase, polyphenol oxidase, and phenylalanine ammonia lyase). The heat map and principal component analysis based on disease, growth and, physico-chemical variables generated useful information regarding the best treatment useful for disease management. Foliar Zn (0.036 mM) acted as a resistance inducer in chili pepper plants that improved activities of antioxidants (CAT and POX), and defense compounds (PPO and PAL), while managing 77% of disease. The study indicated foliar ZnSO4 as an effective and sustainable agriculture practice to manage Alternaria leaf spot disease in chili pepper plants.

William Bartlett (Pyrus communis) pears were diced, packaged and subjected to a short continuous microwave treatment (4.7 min) which increased the temperature from 19.92 ± 1.36 to 101.11 ± 2.50 °C. Retorted samples were processed at 95.40 °C for 18.0 min for comparison. Recorded temperature data were used to calculate C, D and F values. Brix, pH, colour, texture, microbial counts, microstructure and volatile profiles of both treated samples were analysed immediately after process and after 1, 2, 4 and 6 weeks of storage at 4 °C. The C, D and F values of microwaved pears were significantly (p < 0.05) lower compared to those of retorted samples. Both methods of processing resulted in products with standard plate count of < 10 cfu/g during 6 weeks of storage at 4 °C. Microwave processing offered a final product with a total colour difference in the same range as the retorted samples. Polyphenol oxidase enzyme was inactivated below the detection level by both microwave processing and retorting. Microwaved samples also maintained cell wall integrity, although the intercellular intactness was slightly weakened and prevented the final product from developing water-soaked appearance. During storage, volatile profiles of microwaved samples showed significant (p < 0.05) differences, whereas the retort samples showed minimal changes. In comparison to conventional retorting, a short microwave treatment can result in a superior quality end-product with a comparable microbiological quality and a minimum shelf life of 6 weeks at 4 °C.

Phytoremediation is a novel and cost-effective technology for removing contaminants from soil. This study investigated the effect of Chitosan (CS) and Chitosan nanoparticles (CSNPs) on phytoremediation ability of Datura stramonium L. for Cadmium (Cd) polluted soils. The results showed that D. stramonium is an accumulator plant for Cd, with the translocation factor (TF) of 1.12. Its accumulation ability was increased by the application of CS and CSNPs considerably. The concentration of Cd, in the soil, was decreased by increasing application of CS and CSNPs; also CSNPs were more effective in enhancing phytoremediation of Cd, in compared to CS. The application of CS and CSNPs significantly increased the bioconcentration factor (BCF) and TF. The highest BCF (1.85) and TF (1.65) were observed in the group treated by 5% CSNPs, showing the best function for phytoremediation of Cd. Increasing the uptake of Cd, after the CSNPs treatment, could be described as an effect of the small size, higher surface area and the low crystallinity of the nanoparticles. In the leaves of the plants treated with Cd + CS and Cd + CSNPs, the total protein content decreased in comparison to Cd- treated plants, that is the sign of Cd resistance in D. stramonium. Application of CS and CSNPs caused the increase in the peroxidase and polyphenol oxidase activities as compared to the group treated just by Cd. The results, therefore, demonstrated that D. stramonium could be suitable for phytoremediation of Cd-contaminated soils and application of CS and CSNPs could enhance BCF and TF.

Galia melon is an important commodity for Brazilian fresh fruit exports. Significant losses in harvested melon have been attributed to decay, especially caused by Fusarium pallidoroseum, the causal agent of Fusarium rot. Nowadays, the demand for an effective and safe approach to manage postharvest disease has increased. In the current study, two methods of control were studied: UV-C radiation at 2 kJ/m2 and hot water treatment (HWT), which were tested in two different ways. Some fruits were immersed (hot water dipping, HWD) at 52 °C for 2 min, and others were hot water brushed (HWB) at 55, 60, 65, and 70 °C for 15 s. The influence of the treatments on the quality of melon was evaluated by physicochemical parameters, respiration and ethylene emission measurement, and enzymatic analysis. The in vitro tests showed that the dose of 1.0 kJ/m2 of UV-C and the heat treatment at 55 °C for 15 s completely inhibited the spore germination of F. pallidoroseum. HWT by HWD at 52 °C for 2 min and HWB at 65 °C for 15 s, similarly to UVC treatment at 2 kJ/m2, efficiently controlled Fusarium rot in Galia melon, not differing from the imazalil fungicide (100 g a.i./100L) treatment. The UV-C radiation reduced the activities of polyphenol oxidase and peroxidase at specific days of storage. The climacteric peak of respiration occurred on the 16th day for all treatments, and the intensity was significantly lower for UV-C treatment. Ethylene production was not remarkably affected. Consumer acceptance evaluation indicated that fruit treated by heat and UV-C presented better appearance on the 20th day of storage. Those treatments preserved the overall quality of the fruit, delaying the onset of rot symptoms, thus increasing shelf life.

This study investigated the ability of an aqueous extract of Ascophyllum nodosum to directly control the root-knot nematode Meloidogyne javanica and induce nematode resistance in soybean. In a first experiment, soybean plants were inoculated with 2000 eggs and juveniles of M. javanica and treated with extract doses of 0 (control), 25, 50, 75, and 100 g L−1 by two methods of application, soil drenching and foliar spraying. A second experiment evaluated the effect on the hatching percentage of 500 M. javanica eggs. A third experiment assessed defense enzyme activity in inoculated and uninoculated plants treated with A. nodosum extract (75 g L−1) by soil drenching or foliar spraying. This experiment was performed once and analyzed in duplicate. Inoculated and uninoculated untreated plants were included as controls. High extract doses (75 and 100 g L−1) promoted a 65% reduction in nematode population density in soybean. At doses of 32 g L−1 or higher, extract application by soil drenching increased shoot dry weight and plant height. The minimum dose of algal extract to obtain hatching percentages close to 0% was 21.8–22.2 g L−1. Peroxidase, polyphenol oxidase, phenylalanine ammonia-lyase, and glucanase activities were highest in uninoculated drench-treated plants at 12 days after treatment. A. nodosum extract was effective in reducing M. javanica population density in soybean and in vitro egg hatching. The use of the extract also offered potential to the increase in the activity of enzymes related to plant defense in relation to inoculated and untreated control and the uninoculated and untreated control.

Sugar beet (Beta vulgaris L. Chenopodiaceae) has become the first Egyptian crop for sugar production because it contributed with 59.5% of total sugar production. Sclerotium rolfsii is a soil-borne plant pathogenic fungi incident of southern sclerotium rot in sugar beet. The aim of the present study was to investigate the effect of some plant extracts in different solvents as inhibitory control agents against the growth plant pathogen S. rolfsii. Five plant extracts; Roselle, pomegranate, rosemary, black pepper and chamomile were evaluated as inhibitors for Sclerotium rolfsii of sugar beet root rot under laboratory and greenhouse conditions during 2016/2017 growing season at Gemmeiza Agricultural Research Station, (ARC). The results indicated that all tested plant extracts caused remarkable growth inhibition of S. rolfsii compared with control. However, black pepper extract was the most effective against S. rolfsii (recorded 93.33% inhibition). On the other hand, Pomegranate extract in methanol solvent showed also high inhibition percentage (93.30%). All plant extracts mixed with Moncut fungicides demonstrated an antagonistic effect. The pomegranate and black pepper treatments showed the lowest disease severity compared with control. Furthermore, the pomegranate and black paper treatments recorded the highest root weight, root yield/plot, total soluble solids percentage and sucrose content. Also, pomegranate and black pepper treatments reflected the highest amount of total phenols, free phenols, and conjugated phenols. Additionally, the interaction of pomegranate and black pepper treatments with S. rolfsii pathogen, showed the highest activity of oxidative enzymes peroxidase and polyphenol oxidase. This study recommends the application of pomegranate and black pepper as natural alternative fungicides against Sclerotium rolfsii plant infection.

Sustained source-activity is imperative for vigor plant growth and yield. In present study, physio-biochemical responses of wheat plant contributing to source-activity were measured after application of salicylic acid-chitosan nanoparticles (SA-CS NPs). SA-CS NPs slowly release SA for sustained availability to plant. In seedling bioassay, as compared with salicylic acid (SA), SA-CS NPs incurred up to ~1.5 folds increased activities of seed reserve food remobilizing enzymes for substantial mobilization of reserve food to growing seedlings and enhanced seedling vigor index (SVI) by 1.6 folds. At booting stage, foliar application of SA-CS NPs (0.01-0.08%; w/v) enhanced the activities of superoxide dismutase (1.94 folds), catalase (1.33 folds), peroxidase (1.99 folds) and polyphenol oxidase (1.04 folds) in flag leaf. SA-CS NPs further contrived cellular homeostasis by comforting reactive oxygen species (ROS), malondialdehyde (MDA) and proline contents in flag leaf. SA-CS NPs (0.08%; w/v) significantly increased chlorophylls (a-b) contents (1.46 folds), spike length without awns, spike lets per spike and grain weight per pot as compared with SA. Study categorically explicates that slow release of SA from SA-CS NPs could exert significant effect on source-activity by maneuvering various physio-biochemical responses of wheat plant.

A new strategy regarding the fabrication of chitosan (CS) or ethylene diamine tetraacetic acid (EDTA) on graphene oxide (GO) was performed. The nematocidal potential against Meloidogyne incognita causing root-knot infection in eggplant was tested. The plant immune response was investigated through measuring the photosynthetic pigments, phenols and proline contents, oxidative stress, and antioxidant enzymes activity. Results indicating that, the treatment by pure GO recorded the most mortality percentages of M. incognita 2nd juveniles followed by GO-CS then GO-EDTA. In vivo greenhouse experiments reveals that, the most potent treatment in reducing nematodes was GO-CS which recorded 85.42%, 75.3%, 55.5%, 87.81%, and 81.32% in numbers of 2nd juveniles, galls, females, egg masses and the developmental stage, respectively. The highest chlorophyll a (104%), chlorophyll b (46%), total phenols (137.5%), and free proline (145.2%) were recorded in GO-CS. The highest malondialdehyde (MDA) value was achieved by GO-EDTA (7.22%), and hydrogen peroxide (H2O2) content by 47.51% after the treatment with pure GO. Treatment with GO-CS increased the activities of catalase (CAT) by 98.3%, peroxidase (POD) by 97.52%, polyphenol oxidase (PPO) by 113.8%, and superoxide dismutase (SOD) by 42.43%. The synthesized nanocomposites increases not only the nematocidal activity but also the plant systematic immune response.

Blue mold decay is the one of most important postharvest disease of apples caused by the fungus, Penicillium expansum. This study aimed to investigate the biocontrol efficacy of the yeast, Wickerhamomyces anomalus, on postharvest blue mold decay of apples and the relative defense mechanisms. The results indicated that W. anomalus could significantly reduce the blue mold decay of apples, and the maximum inhibition was obtained when the concentration of W. anomalus was 1 × 108 cells ml−1. Furthermore, W. anomalus significantly reduced the fruit decay under ambient conditions, without generating any change in fruit quality. In vitro experiments showed that W. anomalus greatly inhibited the spore germination and germ tube elongation of P. expansum. Besides, its ease of adaptation, stable growth and potential colonization of in apple wounds or surfaces indicated that W. anomalus could compete with P. expansum for nutrients and space, leading to considerable inhibition blue mold decay. W. anomalus significantly induced the activities of polyphenol oxidase (PPO), peroxidase (POD), catalase (CAT), phenylalanine ammonia-lyase (PAL), and ascorbate peroxidase (APX) in apples. Moreover, W. anomalus increased the contents of flavonoid and total phenols. All these results suggested that W. anomalus has potential biocontrol efficacy to control the postharvest blue mold decay of apples

Silicon (Si) is agronomically beneficial due to positive effects it provides to plant development, including the increased defensive response capacity against attack of herbivorous insects. This study evaluated the effects of applications of Si sources via soil and foliar sprays on yellow passion fruit biochemistry and Si-induced resistance to feeding preference and development of the major passion fruit pest, Dione juno juno. Two independent experiments were conducted with applications of calcium silicate (78–88% SiO2) via soil and as foliar sprays with the commercial product AgriSil® (98% SiO2) to plants of Passiflora edulis f. flavicarpa in a greenhouse. Four doses were tested for each Si source plus a control treatment. Biochemical analyses in the plants included the concentrations of Si and total phenolics, and activities of the enzymes peroxidase (POX), phenylalanine ammonia lyase (PAL), and polyphenol oxidase (PPO). Si-induced resistance to D. juno juno was investigated in feeding assays in the laboratory and on the insect’s development on potted-plants in the greenhouse. As main results, calcium silicate favoured the increase in Si content and the activities of POX and PAL, in addition to negatively affecting larvae feeding preference, leaf area consumed, and adult-stage parameters of D. juno juno. Agrisil led to increased Si content, total phenolics concentration, and POX activity, but did not affect the feeding preference, performance, and development of D. juno juno. Calcium silicate is promising for use in integrated pest management and could provide benefits to passion fruit production by reducing the economic losses by D. juno juno attack.

Salicylic acid (SA), a phytohormone, has been considered to be a key regulator mediating plant defence against pathogens. It is still vague how SA activates plant defence against herbivores such as chewing and sucking pests. Here, we used an aphid-susceptible wheat variety to investigate Sitobion avenae response to SA-induced wheat plants, and the effects of exogenous SA on some defence enzymes and phenolics in the plant immune system. In SA-treated wheat seedlings, intrinsic rate of natural increase (rm), fecundity and apterous rate of S. avenae were 0.25, 31.4 nymphs/female and 64.4%, respectively, and significantly lower than that in the controls (P < 0.05). Moreover, the increased activities of phenylalanine-ammonia-lyase, polyphenol oxidase (PPO) and peroxidase in the SA-induced seedlings obviously depended on the sampling time, whereas activities of catalase and 4-coumarate:CoA ligase were suppressed significantly at 24, 48 and 72 h in comparison with the control. Dynamic levels of p-coumaric acid at 96 h, caffeic acid at 24 and 72 h and chlorogenic acid at 24, 48 and 96 h in wheat plants were significantly upregulated by exogenous SA application. Nevertheless, only caffeic acid content was positively correlated with PPO activity in SA-treated wheat seedlings (P = 0.031). These findings indicate that exogenous SA significantly enhanced the defence of aphid-susceptible wheat variety against aphids by regulating the plant immune system, and may prove a potential application of SA in aphid control.

Background: Using ornamental plants for phytoremediation of Heavy Metals (HMs) in soil environments has been grown due to its cost-effectiveness and ease of use in urban environments. The aim of this study was to assess the potential use of Calendula officinalis for soil Copper (Cu) phytoremediation in the presence of different types of chelating agents (Ethylene Diamine Tetra-Acetic Acid (EDTA), Citric acid (CIT), and Tartaric Acids (TAR)) at different levels of Cu in a calcareous soil. Methods: To investigate the effects of stress caused by the use of chelating agents on biochemical changes of C. officinalis, the activity of some antioxidants of C. officinalis (Superoxide Dismutase (SOD), Catalase (CAT), Ascorbate Peroxidase (APX), Peroxidase (POD), and Polyphenol Oxidase (PPO)) was evaluated. Results: As results, C. officinalis showed an increase in shoot and root Cu concentration in the presence of all chelating agents compared to the control. The highest accumulation of Cu in the root/shoot was observed in EDTA-treated plants. However, an increased Cu level in plant parts (due to consuming of EDTA) was corresponded to lower dry weight in shoot and root; higher H2O2 and malondialdehyde (MDA) contents, and antioxidant activity (APX, PPO, CAT, SOD, and POD) in plants compared to the control treatment. On the contrary, the application of CIT and TAR primarily increased shoot and root dry weight and Cu concentration. Conclusion: Generally, the results of this study could be suggested that plants possess a well-organized resistance mechanism against oxidative stress caused by using of CIT and TAR.

The genus Streptomyces demonstrates enormous promise in promoting plant growth and protecting plants against various pathogens. Single and consortium treatments of two selected Streptomyces strains (Streptomyces shenzhenensis TKSC3 and Streptomyces sp. SS8) were evaluated for their growth-promoting potential on rice, and biocontrol efficiency through induced systemic resistance (ISR) mediation against Xanthomonas oryzae pv. oryzicola (Xoc), the causal agent of rice bacterial leaf streak (BLS) disease. Seed bacterization by Streptomyces strains improved seed germination and vigor, relative to the untreated seed. Under greenhouse conditions, seed bacterization with consortium treatment TKSC3 + SS8 increased seed germination, root length, and dry weight by 20%, 23%, and 33%, respectively. Single and consortium Streptomyces treatments also successfully suppressed Xoc infection. The result was consistent with defense-related enzyme quantification wherein single and consortium Streptomyces treatments increased peroxidase (POX), polyphenol oxidase, phenylalanine ammonia-lyase, and β,1-3 glucanase (GLU) accumulation compared to untreated plant. Within all Streptomyces treatments, consortium treatment TKSC3 + SS8 showed the highest disease suppression efficiency (81.02%) and the lowest area under the disease progress curve value (95.79), making it the best to control BLS disease. Consortium treatment TKSC3 + SS8 induced the highest POX and GLU enzyme activities at 114.32 μmol/min/mg protein and 260.32 abs/min/mg protein, respectively, with both enzymes responsible for plant cell wall reinforcement and resistant interaction. Our results revealed that in addition to promoting plant growth, these Streptomyces strains also mediated ISR in rice plants, thereby, ensuring protection from BLS disease.

Mango (Mangifera indica L.) is a tropical fruit which is climacteric and highly perishable. Consequently, it is indispensable to address postharvest management techniques by applying eco-friendly technologies to reduce crop losses. Thus, the current study was conducted to evaluate Aloe vera gel’s influence alone and chitosan and calcium chloride (CaCl2) on mango shelf life during the storage time at the ambient temperature (25 ± 2 °C) for 21 days. The results exhibited that A. vera-chitosan coatings were able to remarkably decrease weight loss and ascorbic acid reduction throughout the storage period. Total phenol and antioxidant activity progressively diminished during the storage, and control fruits exhibited the lowest content of the phenol content and antioxidant activity during the storage. The highest correlation (R = 0.95) between antioxidant and ascorbic acid was observed in the A. vera-chitosan treated fruits. Control fruits showed the lowest catalase (CAT) and peroxidase (POD) enzyme activity during the storage time. A. vera-chitosan coating significantly inhibited the activity of polyphenol oxidase (PPO) during the storage period. Oppositely, the coating had no significant effect on total soluble solids (TSS) and titratable acidity (TA) at the end of the experiment. The discoloration trend of the fruits coated with A. vera enriched with chitosan was significantly delayed compared to the control fruits. Finally, A. vera-chitosan coating could be suggested as a suitable coating to preserve the quality of mango fruit throughout storage at the ambient temperature.

The novelty of the present research is conducting a new method in the systemic resistance of plant diseases by using distinct marine extracts. The ability of two octopus extracts to reduce the wilt disease caused by Fusarium oxysporum was observed. The applied methods are soaked roots (SR) and foliar shoots (FS). The antioxidant enzyme activities, percent disease index (PDI), and growth parameters were measured. In vitro antifungal potential of the octopus extracts against F. oxysporum was examined. The obtained result shows that SR extracts reduced PDI. Additionally, all the tested treatments promoted the growth and photosynthetic pigments of the infected plants. SR (in ethanolic extracts) was the most prominent inducer which offered a high advancement in the total soluble protein contents. Also, SR (in methanolic extracts) was the most suitable inducer which provided a very necessary development not only in the total phenol but also in the peroxidase (POD) and polyphenol oxidase (PPO) activities. GC-MS investigation of the octopus extracts exhibited that the compounds which possess antifungal activity were furoscrobiculin B and/or eugenol. They demonstrated a notable antifungal potential against F. oxysporum with a maximum activity of 38.5 and 12.7 mm ZOI after the treatment with the ethanolic and methanolic extract, respectively. FTIR results illustrated the functional group of the compound responsible for the antifungal activity. Additionally, an atomic absorption result reveals that there are traces of metals detected such as Pb, Ag, Cu, Zn, and Mg. The antifungal activity was decreased as the concentrations were reduced. Accordingly, the present extracts may be used as the vital agents in the agricultural field to restrain the plant pathogenic fungi, especially F. oxysporum from a proliferation.

The comparative of some abiotic compounds (Ascorbic acid, Citric acid, DL-Aspartic acid, Indole-3Acetic acid, Indole-3Butyric acid, DL-leucine, Gibberllic acid, L-Arginine and Sulfosalicylic acid), as resistance inducing for managing Meloidogyne javanica infecting tomato (Super strain B Australian cv.) was studied under greenhouse conditions. The results showed that all tested compounds reduced all nematode parameters compared with untreated control. Application of Citric acid caused a superior effect in the reduction percentage of J2 in soil (95.2%) followed by L-arginine (92.9%) and then Gibberllic acid (92.2%). Also, DL-Aspartic acid gave the highest effect in the reduction percentage of root galls (95.6%) followed by Citric acid and then L-Arginine acid as following (94.3% and 93.02%) respectively compared with untreated control. The treatments of L-arginine followed by Gibberllic acid were recorded the best in plant growth response of tomato plants compared with the untreated control. Tested abiotic agent inducers activators had the potential to suppress M. javanica infection through the stimulation of tomato tolerance. Most of the treatments showed a significant reduction in the percentage values of total and non-reducing sugars comparing with infected and healthy control, while Sulfosalicylic acid and L-arginine recorded high amounts in total and non-reducing sugars. On the other hand, Dl-Aspartic acid, Indol-3Acetic acid and Citric acid showed a high percentage of total phenols comparing with untreated control. Among all treatments, only Dl-leucine showed a significant increment in proline comparing with untreated control and healthy control. The level of Polyphenol oxidase and peroxidase activity increased in the treated plants compared with untreated plants.

Relevance. Oxidative reactions (based on peroxidase activity, POX and polyphenol oxidase, PPO; hydrogen peroxide content) that occur in response to infection or reinfection of the off-spring of infected plants depend on the type of host-virus interaction (sensitive, tolerant, stable) and the nature of the interaction with viral infection (primary infection, reinfection of second and third generations).Results. Reinfection with tomato aspermy virus (TАV) or tobacco mosaic virus (TMV) of the off-spring of third infected tomato generation caused a significant decrease in POX activity compared to successive generations of infected plants (G2) for Craigella (Tm-22/Tm- 22) and S. pimpinellifolium genotypes or an increase for Rufina and Craigella (Tm-1/Tm-1) ones. In genotypes containing resistance genes, Rufina and Craigella, no differences were observed in PPO of TMV primary infection and control, while significant differences were found in case of TAV (susceptibility). As a result of TMV infection, the sensitive (Elvira) and tolerant (S. pimpinellifolium) genotypes showed an increase in PPO values compared to the control. At the same time, in most genotypes primarily / secondarily infected with TAV or TMV, statistically significant differences were revealed in the activity of POX or PPO, as well as the accumulation of hydrogen peroxide in plant leaves, which indicates specific protective reactions of the genotypes.

This study aimed to investigate the effect of Pichia galeiformis on disease resistance and elucidate the changes in phenylpropane biosynthesis treated by P. galeiformis in postharvest citrus. The results showed that P. galeiformis reduced the disease incidence and lesion diameters without direct contact with the pathogen Penicillium digitatum. Transcriptome analysis revealed that phenylpropanoid biosynthesis was triggered by P. galeiformis. Genes encoding phenylpropanoid biosynthesis were upregulated, including phenylalanine ammonia-lyase (PAL), 4-coumaroyl-CoA ligase (4CL), cinnamate-4-hydroxylase (C4H), peroxidase (POD), cinnamyl alcohol dehydrogenase (CAD), O-methyltransferase, and hydroxyl cinnamoyl transferase. Moreover, P. galeiformis increased the activity of PAL, 4CL, C4H, POD, polyphenol oxidase, and CAD in citrus pericarp. In addition, P. galeiformis treated citrus displayed higher levels of total phenolic compounds, flavonoid, and lignin and higher amounts of ferulic and sinapic acid. In conclusion, these results suggested that P. galeiformis could induce resistance through modulating the pathway of phenylpropanoid biosynthesis in postharvest citrus.

The Cd accumulating difference in edible parts of leafy vegetables were involvement with the cultivar-dependent oxidation resistance of plants. According to the transcriptomic results, the total expression of the 4 major antioxidase genes in Cd pollution-safe cultivars (Cd-PSCs) under control condition were higher than in high-Cd-accumulating cultivars (HCCs) of the 4 tested leafy vegetables, indicating the cultivar-dependent high oxidation resistance of Cd-PSCs. Simultaneously, expression of superoxide dismutase (SOD) and peroxidase (POD) genes in Cd-PSCs were all higher than in HCCs under control condition. The real detection of SOD activities in Cd-PSCs under control condition were higher than in HCCs, which verified the transcriptomic results. What’s more, there were no uniform response mechanisms of antioxidase genes to cope with Cd stress among the 4 tested leafy vegetables, even 3 of them were native from the same genus Brassica. Meanwhile, expression of the 4 major antioxidase genes were difference from genus, such as the polyphenol oxidase (PPO) genes were hardly expression in genus Brassica. These results would contribute to the understanding the inherent difference between Cd-PSCs and HCCs, and the cultivar-dependent Cd oxidation resistance related to Cd-PSCs might a easy signal for in vitro catching and screening.

Insecticidal control of foliar pests is often accompanied by secondary oxidative stresses in treated plants. Pyridalyl and five insect growth regulators (IGRs), diflubenzuron, chromafenozide, chlorfluazuron, lufenuron and hexaflumuron were tested for their efficacy and persistence against 4th instar larvae of Spodoptera littoralis (Boisd.) in field-laboratory bioassay experiments at Sakha Agricultural Research Station, Kafrelsheikh, Egypt. The potentiality of theses insecticides to induce oxidative stress in cotton plants (Gossypium barbadense Linnaeus var. Giza 92) was assessed via determination of the activity of the antioxidative enzymes: superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and polyphenol oxidase (PPO) as well as total protein content. Pyridalyl exhibited the highest initial effect (96.5% mortality) and mean residual activity (68% mortality) against S. littoralis followed by hexaflumuron and diflubenzuron, while lufenuron resulted in the lowest initial effect and mean residual activity of 88.1% and 44.9% mortality, respectively. Pyridalyl was the most persistent on cotton plants (LT50 = 9.5 days) relative to the tested IGRs (LT50 = 5.78–7.54 days). Exposure of cotton to the tested insecticides caused oxidative stress to the treated plants in a concentration-dependent manner manifested in significant elevation of the activity of SOD, CAT, POD and PPO comparing to untreated ones. The IGRs varied in their ability to induce oxidative stress, and the maximum was recorded in the chlorfluazuron treatment. The total protein content significantly increased after application of the tested insecticides, and the increase was more pronounced in the treatments that contained a pyridine ring in their chemical structure i.e., chlorfluazuron and pyridalyl.

Cotton leaf worm (Spodoptera littoralis) is considered one of the most destructive agricultural pests in Egypt. It is overcome by the producer by using chemical pesticides, but that leads to the appearance of new generations and causes environmental pollution. So in the present investigation six soybean genotypes (Giza-82, Giza 22, Giza 83, Giza 21, Giza 35 and Giza 111) were planted under natural infection with cotton leaf worm. The effect of two elicitors, methyl jasmonate (20 µM MeJA) and sodium nitroprusside (500 µM SNP) on the six soybean genotypes was studied to enhance the ability of the susceptible genotypes to resist cotton leaf worm. Results showed that Giza 35 and Giza 111 showed tolerance performance under natural infection compared to Giza 22 and Giza 82 as sensitive ones, while Giza 83 and Giza 21 showed moderate tolerance. Treatments with MeJA and SNP positively affected contents of secondary metabolites (phenol, flavonoid and tannin), non-enzymatic antioxidants (anthocyanin, tocopherol and ascorbic acid) and enzymatic antioxidants (catalase, peroxidase, polyphenol oxidase and Guaiacol peroxidase) in shoots of all soybean genotypes. Treatment with MeJA was found to be more effective than SNP and enhanced the resistance of the susceptible genotypes. In conclusion, treatment of soybean plants with MeJA and SNP would be effective enhancing the ability of these plants to resists cotton leaf worm infection and increased secondary metabolites and antioxidants responsible for plant defense.

BACKGROUND Rice spikelet rot disease (RSRD) is an emerging disease that significantly reduces rice yield and quality. In this study, we evaluated the potential use of the broad-spectrum endophytic fungus Phomopsis liquidambaris B3 as a biocontrol agent against RSRD. We also compared the control effects of different treatments, including chemical fungicides and treatment with multiple strains and single strains in combination or individually, against RSRD. The objective of this study was to find an effective and environmentally friendly control strategy to reduce the occurrence of RSRD and improve the rice yield. RESULTS In pot experiments, the effect of B3 alone was better than that of fungicide or combined measures. The results showed that root colonization by B3 significantly reduced the incidence and disease index of RSRD by 41.0% and 53.8%, respectively. This was related to enhanced superoxide dismutase (SOD), peroxidase (POD), and polyphenol oxidase (PPO) activity, and to significantly upregulated expression levels of OsAOX, OsLOX, OsPAL, and OsPR10 in rice. Moreover, B3 improved the diversity of the bacterial community rather than the fungal community in the rice rhizosphere. It also led to a decrease in Fusarium proliferatum colonization and fumonisin content in the grain. Finally, root development was markedly promoted after B3 inoculation, and the yield improved by 48.60%. The result of field experiments showed that the incidence of RSRD and the fumonisin content were observably reduced in rice receiving B3, by 24.41% and 37.87%, respectively. CONCLUSION The endophytic fungus Phomopsis liquidambaris B3 may become an effective tool to relieve rice spikelet rot disease. © 2020 Society of Chemical Industry.

Bacterial blight of rice caused by Xanthomonas oryzae pv. oryzae (Xoo) is an important disease of rice causing significant yield losses. Currently, there are ten highly diverse pathotypes of Xoo prevalent in Punjab state of India. Breeding for and deploying host plant resistance is the most economical approach for the management of this disease. But pathogen variability coupled with uncertainties in prevailing weather conditions due to climate change poses serious threat to the durability of R genes and makes the plant vulnerable to attack by the pathogen. During the current study, biochemical basis of resistance of two R genes, Xa4 and Xa7 was studied at different temperature regimes and five pathotypes of Xoo viz. PbXo-4, PbXo-7, PbXo-8, PbXo-10 and Sgr-1001. Level of resistance in Xa4 and Xa7 genes was observed to be highly correlated with the expression of three defense related enzymes viz. peroxidase, polyphenol oxidase and phenylalanine ammonia lyase. It was further observed that the expression of Xa4 and Xa7 was influenced by temperature as Xa4 showed increased effectiveness at lower temperature while Xa7 was more effective at high temperature. The differential pattern of lesion length progression on these near isogenic lines in response to different temperature regimes also suggests the level of quantitative resistance imparted by these genes.

Cereal leaf beetle (CLB, Oulema spp.) are economically important pests of cereals, because their feeding, especially at the larval stage may significantly reduce the quality and quantity of the obtained crop. The aim of the study was explanation the expression level of PPO and PAL genes involved in the secondary metabolites production in response to feeding of CLB larvae with a reduced or not reduced bacterial component. It was indicated that bacteria associated with CLB larvae supressed wheat response to CLB feeding to the benefit of insect host. Each of the three wheat varieties developed a unique defence mechanism against tested stress factors (including mechanical damage or damage caused by larvae feeding). The Arkadia variety reacted much faster and stronger to treatments in comparison to the other two wheat varieties. Understanding of the expression of genes involved in the plant defence response against herbivory pests is very important from an ecological point of view and has a great potential for use in plant protection.

Chitosan-Gelatin (CHI-Gel) based edible coating incorporated with longkong pericarp extract (LPE) was developed and investigated for its impact on the quality of black tiger shrimp (Penaeus monodon) during refrigerated storage (4 ​°C) for 20 days. Shrimp coated with CHI-Gel-LPE (1.5%) had better quality indices than control (no coating), those coated with CHI, CHI-Gel, and CHI-Gel-LPE at lower concentrations (0.5 and 1%). The CHI-Gel-LPE inhibited melanosis and polyphenol oxidase (PPO) and controlled the pH changes in a dose-dependent manner. Lipid oxidation indices such as TBARS, PV, p-anisidine, and totox values were significantly controlled by the treatments throughout the storage. The CHI-GEL-LPE-1.5% coated sample had the lowest protein oxidation, and it's ascertained by the lowest loss of sulfhydryl groups, with the lowest carbonyl content throughout the storage (P ​

The present investigation was undertaken to study the chemical and biochemical parameters of selected powdery mildew resistant and susceptible genotypes of fenugreek. It is observed that the Kasuri selection - 2 was found immune, Purandar local-1 found moderately susceptible and Lasalgaon as highly susceptible. Rest of fifteen varieties were found susceptible. It is observed that the activity of polyphenol oxidase (PPO) and peroxidase (PO) enzymes were higher in immune variety (Kasuri selection-2) as compared to susceptible varieties before and after incidence of powdery mildew and has shown negative significant correlation (-0.766) for (PPO) and (-0.569) for (PO) after 80 DAS with PDI. It is concluded that total chlorophyll content in immune variety was higher than susceptible varieties, before (40 DAS) and after (80 DAS) incidence of powdery mildew and has shown negative significant correlation (-0.654) and (-0.741) at 40 DAS and 80 DAS, respectively with PDI. The activity of polyphenol oxidase (PPO) and peroxidase (PO) enzymes were higher in immune variety (Kasuri selection-2) as compared to susceptible varieties before and after incidence of powdery mildew. The nitrogen concentration has direct relation with powdery mildew of fenugreek. However, there was no concrete relation with other macro or micronutrient concentration in fenugreek with powdery mildew disease.

When a plant is under heavy metals stress, it has different mechanism of coping with it. Brassica oleracea var. acephala (kale) is a plant that has an ability of heavy metal accumulation and removal of heavy metals from the ground. The plants were exposed to 50, 100, 200, and 500 μM of CdCl2 for 5days, in controlled in vitro conditions. Root length was measured to confirm the Cd effect on plant growth. There are five key antioxidants enzymes responsible for the regulation of heavy metals stress: superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), Peroxidase (POD) and Polyphenol oxidase (PPO). All enzymes showed significant activity, especially triggered by 500 μM CdCl2 in both varieties. The domestic sorts seem more resistant if compared to hybrid variety, showing significant lower expression of antioxidants enzymes at higher concentrations. In general, significant percentage of enzymes is more expressed in the hybrid Italian sort, Nero di Toscana, indicating the ability of domestic sorts to be more resistant to heavy metal stress.

Deactivation of polyphenol oxidase (PPO) in natural products is essential for downstream processing of functional molecules used as food or food additives, particularly those served as antioxidants. In the present work, we identified two proteins with PPO activity from lowbush blueberry using ammonium sulphate precipitation and chromatography procedures. Deactivation of these proteins was studied using aqueous solutions of ethanol of different concentrations. The PPO activity was recovered after ethanol removal for the protein samples previously soaked in a low concentration ethanol solution. A complete and unrecoverable deactivation of the proteins was achieved using ethanol with concentration over 70% (v/v), as manifested by the significant changes in circular dichroism (CD) and fluorescence spectroscopy measurements. Based on these findings, we propose a new extraction process for blueberry anthocyanin, in which an ethanol shock, i.e. soaking blueberry fruit in a 70% (v/v) ethanol solution for 1 h, is implemented before subsequent procedures. This new process increases the anthocyanin yield by 55% in comparison to that without the ethanol shock.