Use of natural-based commercial products as an alternative for providing bioprotection against verticillium wilt of olive.

BACKGROUND: As a result of the ineffectiveness of existing control methods against Verticillium dahliae, the causal agent of verticillium wilt of olive (Olea europaea; VWO), it is necessary to search for sustainable and environmentally friendly alternatives, such as bioprotection by products based on plant extracts and other naturally synthesized compounds. Therefore, present study aimed to evaluate the effects of seven natural-based commercial products on the inhibition of mycelial growth, the germination of V. dahliae conidia and microsclerotia, and disease progression in olive plants (cv. Picual). Aluminium lignosulfonate and a copper phosphonate salt (copper phosphite) were included for comparative purposes. RESULTS: The seaweed and willow extracts and copper phosphite inhibited V. dahliae mycelial growth by more than 50% at the high doses tested. Most of the products inhibited conidial germination by up to 90% compared to the control at the high doses tested. However, none of the products showed efficacy above 50% in inhibiting microsclerotia germination. The willow extract was the most effective at reducing disease severity and progression in olive plants, with no significant differences compared to the non-inoculated negative control. CONCLUSION: The results of the present study suggest that the use of natural-based products (i.e. seaweed and willow extracts) is a potential sustainable alternative in an integrated VWO control strategy. © 2024 Society of Chemical Industry.

Enhanced control efficacy of Bacillus subtilis NM4 via integration of chlorothalonil on potato early blight caused by Alternaria solani.

Early blight caused by Alternaria solani is a common foliar disease of potato around the world, and serious infections result in reduced yields and marketability due to infected tubers. The major aim of this study is to figure out the synergistic effect between microorganism and fungicides and to evaluate the effectiveness of Bacillus subtilis NM4 in the control of early blight in potato. Based on its colonial morphology and a 16S rRNA analysis, a bacterial antagonist isolated from kimchi was identified as B. subtilis NM4 and it has strong antifungal and anti-oomycete activity against several phytopathogenic fungi and oomycetes. The culture filtrate of strain NM4 with the fungicide effectively suppressed the mycelial growth of A. solani, with the highest growth inhibition rate of 83.48%. Although exposure to culture filtrate prompted hyphal alterations in A. solani, including bulging, combining it with the fungicide caused more severe hyphal damage with continuous bulging. Surfactins and fengycins, two lipopeptide groups, were isolated and identified as the main compounds in two fractions using LC-ESI-MS. Although the surfactin-containing fraction failed to inhibit growth, the fengycin-containing fraction, alone and in combination with chlorothalonil, restricted mycelial development, producing severe hyphal deformations with formation of chlamydospores. A pot experiment combining strain NM4, applied as a broth culture, with fungicide, at half the recommended concentration, resulted in a significant reduction in potato early blight severity. Our results indicate the feasibility of an integrated approach for the management of early blight in potato that can reduce fungicide application rates, promoting a healthy ecosystem in agriculture.

Fungicidal properties of ginger (Zingiber officinale) essential oils against Phytophthora colocasiae.

Recently, plant essential oils (EOs) have attracted special attention in plant disease control and food preservation. Since ancient times, essential oils extracted from plants have exhibited many biological characteristics, especially antimicrobial properties. Recent studies have described the potentials of EOs and derivatives to inhibit the growth and reproduction of microorganisms, mainly in response of overwhelming concerns of consumers about food safety. In the context of returning to nature, with the advancement of science and technology and improved living standards, people have begun to seek solutions for food hygiene without chemical additives. Therefore, biological pesticides and plant-oriented chemicals have received special attention from scientists because they are environmentally friendly and nonhazardous, sustainable, and effective alternatives against many noxious phytopathogens. Present study is intended to appraise the fungicidal properties of ginger EOs to combat leaf blight disease of taro, which threatens global taro production. Farmers often hinge on extremely toxic synthetic fungicides to manage diseases, but the residual effects and resistance of chemicals are unavoidable. The microwave-assisted hydrodistillation method was used for ginger EOs extraction and an FTIR (ATR) spectrometer was used to evaluate their chemical composition and citral was identified as most abundant compound (89.05%) in oil. The pathogen isolated from lesions of diseased taro plants was identified as Phytophthora colocasiae and used as test fungus in the present study. Ginger EO was evaluated in-vitro for antifungal properties against mycelium growth, sporangium production, zoospore germination, leaf, and corm necrosis inhibition. Repeated experiments have shown that the concentration of ginger essential oil (1250 ppm) proved to be the lowest dose to obtain 100% inhibition of fungal growth and spore germination, sporangia formation and leaf necrosis assessment. These results are derived from this fungal species and a hypothesis that involves further research on other plant pathogens to demonstrate the overall potency of essential oils. This study references the easy, economic, and environmental management and control of plant diseases using essential oils and byproducts.

Characterization of Alternaria porri causing onion purple blotch and its antifungal compound magnolol identified from Caryodaphnopsis baviensis.

Alternaria porri (Ellis) Clf. causes purple blotch disease on Allium plants which results in the reduction of crop yields and quality. In this study, to efficiently find natural antifungal compounds against A. porri, we optimized the culture condition for the spore production of A. porri and the disease development condition for an in vivo antifungal assay. From tested plant materials, the methanol extracts derived from ten plant species belonging to the families Cupressaceae, Fabaceae, Dipterocarpaceae, Apocynaceae, Lauraceae, and Melastomataceae were selected as potent antifungal agents against A. porri. In particular, the methanol extract of Caryodaphnopsis baviensis (Lec.) A.-Shaw completely inhibited the growth of A. porri at a concentration of 111 µg/ml. Based on chromatographic and spectroscopic analyses, a neolignan compound magnolol was identified as the antifungal compound of the C. baviensis methanol extract. Magnolol showed a significant inhibitory activity against the spore germination and mycelial growth of A. porri with IC50 values of 4.5 and 5.4 µg/ml, respectively. Furthermore, when magnolol was sprayed onto onion plants at a concentration of 500 µg/ml, it showed more than an 80% disease control efficacy for the purple blotch diseases. In terms of the antifungal mechanism of magnolol, we explored the in vitro inhibitory activity on individual oxidative phosphorylation complexes I-V, and the results showed that magnolol acts as multiple inhibitors of complexes I-V. Taken together, our results provide new insight into the potential of magnolol as an active ingredient with antifungal inhibitory action to control purple blotch on onions.

Inhibitory Effect of Osthole from Cnidium monnieri (L.) Cusson on Fusarium oxysporum, a Common Fungal Pathogen of Potato.

Fusarium wilt of potato is one of the most common diseases of potato in China, and is becoming a serious threat in potato production. It has been reported that osthole from Cnidium monnieri (L.) Cusson can inhibit plant pathogens. Here, we test the anti-fungal activity of C. monnieri osthole against Fusarium oxysporum in potatoes. The results showed that at a concentration of 5 mg/mL, osthole was able to obviously inhibit mycelial growth of F. oxysporum. We found that osthole caused changes of mycelial morphology, notably hyphal swelling and darkening. Osthole significantly reduced the spore germination of Fusarium by 57.40%. In addition, osthole also inhibited the growth of other pathogens such as Fusarium moniliforme J. Sheld, Thanatephorus cucumeris Donk, and Alternaria alternata (Fr.) Keissl, but not Alternaria solani Jonesetgrout and Valsa mali Miyabe and G. Yamada. Our results suggest that osthole has considerable potential as an agent for the prevention and treatment of potato Fusarium wilt.

Antifungal Activities of cis-trans Citral Isomers against Trichophyton rubrum with ERG6 as a Potential Target.

Trichophyton rubrum causes ringworm worldwide. Citral (CIT), extracted from Pectis plants, is a monoterpene and naturally composed of geometric isomers neral (cis-citral) and geranial (trans-citral). CIT has promising antifungal activities and ergosterol biosynthesis inhibition effects against several pathogenic fungi. However, no study has focused on neral and geranial against T. rubrum, which hinders the clinical application of CIT. This study aimed to compare antifungal activities of neral and geranial and preliminarily elucidate their ergosterol biosynthesis inhibition mechanism against T. rubrum. Herein, the disc diffusion assays, cellular leakage measurement, flow cytometry, SEM/TEM observation, sterol quantification, and sterol pattern change analyses were employed. The results showed geranial exhibited larger inhibition zones (p < 0.01 or 0.05), higher cellular leakage rates (p < 0.01), increased conidia with damaged membranes (p < 0.01) within 24 h, more distinct shriveled mycelium in SEM, prominent cellular material leakage, membrane damage, and morphological changes in TEM. Furthermore, geranial possessed more promising ergosterol biosynthesis inhibition effects than neral, and both induced the synthesis of 7-Dehydrodesmosterol and Cholesta-5,7,22,24-tetraen-3ß-ol, which represented marker sterols when ERG6 was affected. These results suggest geranial is more potent than neral against T. rubrum, and both inhibit ergosterol biosynthesis by affecting ERG6.

Growth Restriction of Rhizoctonia solani via Breakage of Intracellular Organelles Using Crude Extracts of Gallnut and Clove.

Plant diseases reduce crop yield and quality, hampering the development of agriculture. Fungicides, which restrict chemical synthesis in fungi, are the strongest controls for plant diseases. However, the harmful effects on the environment due to continued and uncontrolled utilization of fungicides have become a major challenge in recent years. Plant-sourced fungicides are a class of plant antibacterial substances or compounds that induce plant defenses. They can kill or inhibit the growth of target pathogens efficiently with no or low toxicity, they degrade readily, and do not prompt development of resistance, which has led to their widespread use. In this study, the growth inhibition effect of 24 plant-sourced ethanol extracts on rice sprigs was studied. Ethanol extract of gallnuts and cloves inhibited the growth of bacteria by up to 100%. Indoor toxicity measurement results showed that the gallnut and glove constituents inhibition reached 39.23 µg/mL and 18.82 µg/mL, respectively. Extract treated rice sprigs were dry and wrinkled. Gallnut caused intracellular swelling and breakage of mitochondria, disintegration of nuclei, aggregation of protoplasts, and complete degradation of organelles in hyphae and aggregation of cellular contents. Protection of Rhizoctonia solani viability reached 46.8% for gallnut and 37.88% for clove in water emulsions of 1000 µg/mL gallnut and clove in the presence of 0.1% Tween 80. The protection by gallnut was significantly stronger than that of clove. The data could inform the choice of plant-sourced fungicides for the comprehensive treatment of rice sprig disease. The studied extract effectively protected rice sprigs and could be a suitable alternative to commercially available chemical fungicides. Further optimized field trials are needed to effectively sterilize rice paddies.

Antifungal activity of propyl disulphide from neem against Lasiodiplodia theobromae and Neofusicoccum parvum causing stem end rot in mango.

AIM: To investigate the antifungal effect of the neem extract volatile propyl disulphide against the fungal plant pathogens. METHODS AND RESULTS: Postharvest pathogens were isolated and identified as Lasiodiplodia theobromae and Neofusicoccum parvum causing the stem end rot of mango fruit. Antifungal activity of propyl disulphide at different concentrations was determined in comparison with ethanol and distilled water. Both diffusion assays were effective in controlling the mycelial growth of the tested fungi. The high coefficient of determination (R2 , 0·970-0·997) of the growth curves indicated the good fit of the experimental data to the Gompertz growth model. Propyl disulphide significantly (P ≤ 0·05) decreased the mycelial growth during the stationary phase (A) and increased the lag phase (λ) than both control (ethanol and distilled water). CONCLUSION: This compound can potentially be applied to other tropical and subtropical fruits for the successful control of postharvest losses of fresh produce. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report of propyl disulphide from neem extract against plant pathogens and could be beneficial for effective microbial decay prevention in food industries.

Verticillium dahliae VdTHI20, Involved in Pyrimidine Biosynthesis, Is Required for DNA Repair Functions and Pathogenicity.

Verticillium dahliae (V. dahliae) infects roots and colonizes the vascular vessels of host plants, significantly reducing the economic yield of cotton and other crops. In this study, the protein VdTHI20, which is involved in the thiamine biosynthesis pathway, was characterized by knocking out the corresponding VdTHI20 gene in V. dahliae via Agrobacterium tumefaciens-mediated transformation (ATMT). The deletion of VdTHI20 resulted in several phenotypic defects in vegetative growth and conidiation and in impaired virulence in tobacco seedlings. We show that VdTHI20 increases the tolerance of V. dahliae to UV damage. The impaired vegetative growth of ΔVdTHI20 mutant strains was restored by complementation with a functional copy of the VdTHI20 gene or by supplementation with additional thiamine. Furthermore, the root infection and colonization of the ΔVdTHI20 mutant strains were suppressed, as indicated by green fluorescent protein (GFP)-labelling under microscope observation. When the RNAi constructs of VdTHI20 were used to transform Nicotiana benthamiana, the transgenic lines expressing dsVdTHI20 showed elevated resistance to V. dahliae. Together, these results suggest that VdTHI20 plays a significant role in the pathogenicity of V. dahliae. In addition, the pathogenesis-related gene VdTHI20 exhibits potential for controlling V. dahliae in important crops.

Influence of selenium yeast on the growth, selenium uptake and mineral composition of Coriolus versicolor mushroom.

The ability of Coriolus versicolor medicinal mushroom to grow and accumulate selenium during submerged cultivation in a selenium-fortified medium is examined in this paper. For selenium supplementation, commercial selenium yeast was used. Control, nonenriched sample and reference cultures cultivated in the medium enriched with commercial yeast Saccharomyces cerevisiae were also prepared. The mushroom demonstrated a high ability to accumulate selenium from the added source (around 970 and 1,300 µg/g of dry mycelium weight for samples enriched with selenium in a concentration of 10 and 20 mg Se/L, respectively). The addition of selenium significantly (p ≤ .05) increased the biomass yield, whereas the addition of nonenriched yeast had no significant (p ≤ .05) impact. Furthermore, regression analysis showed statistically significant (p ≤ .05) and positive correlations between the content of Se and Fe (r = .92), Se and Cu (r = .92), Se and Mn (r = .98), and Se and Sr (r = .96), suggesting that selenium incorporation was followed by incorporation of these elements, and led to mineral enrichment of the obtained mycelium. Methanol extracts prepared from mycelium biomass demonstrated a better inhibitory effect on Gram-positive bacterial strains with minimal inhibitory concentrations between <0.3125 and 40 mg/ml. The obtained results showed that selenium yeast could be used for obtaining a potential novel food supplement: mushroom biomass with high selenium content and enhanced mineral composition.

The antimicrobial activity of protein elicitor AMEP412 against Streptomyces scabiei.

In this paper, we report the antimicrobial activity of AMEP412 (a protein elicitor from Bacillus subtilis) against Streptomyces scabiei, which is the potato common scab pathogen. The purified protein samples showed an obvious inhibition zone on an S. scabiei agar plate, and the minimum inhibition concentration detected was 50 µg mL-1. The fluorescence localization assay revealed that AMEP412 could bind to aerial mycelia and spores. The stability test showed that AMEP412 was stable at 60 °C for 30 min and in pH values from 5.0 to 10.0. Its antimicrobial activity was not sensitive to metal cations. However, its activity declined by 23% when treated with Proteinase K, and was completely abrogated with Tween 80 treatment. Three antimicrobial peptides (GS21, GY20 and GY23) were identified from AMEP412, which further verified its antimicrobial activity. This research reveals the antimicrobial function of AMEP412, which not only enriches the function of the protein elicitor, but also provides a candidate for the biocontrol of potato common scab.

Effects of sophorolipids on fungal and oomycete pathogens in relation to pH solubility.

AIMS: The objective of this study was to determine the effects of sophorolipids on several fungal and oomycete plant pathogens and the relationship between sophorolipids at different pH and antimicrobial activities. METHODS AND RESULTS: Sophorolipids had different solubility at different pH with a dramatic increase in solubility when pH was 6 or higher. Inhibition of mycelial growth of Phytophthora infestans by sophorolipids was affected by pH values, showing that when the pH value was higher, the inhibition rate was lower. Sophorolipids inhibited spore germination and mycelial growth of several fungal and oomycete pathogens in vitro including Fusarium sp., F. oxysporum, F. concentricum, Pythium ultimum, Pyricularia oryzae, Rhizoctorzia solani, Alternaria kikuchiana, Gaeumannomyces graminis var. tritici and P. infestans and caused morphological changes in hyphae by microscope observation. Sophorolipids reduced ß-1,3-glucanase activity in mycelia of P. infestans. In greenhouse studies, foliar application of sophorolipids at 3 mg ml-1 reduced severity of late blight of potato caused by P. infestans significantly. CONCLUSION: Sophorolipids influenced spore germination and hyphal tip growth of several plant pathogens and pH solubility of sophorolipids had an effect on their efficacy. Application of sophorolipids reduced late blight disease on potato under greenhouse conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: The findings indicated that sophorolipids have the potential to be developed as a convenient and easy-to-use formulation for managing plant diseases.

Selenium reduces the pathogenicity of Sclerotinia sclerotiorum by inhibiting sclerotial formation and germination.

Sclerotinia sclerotiorum (S. sclerotiorum) is a devastating fungal pathogen with worldwide distribution, and threatened the agro-ecological safety in the long term. To control the damage caused by Sclerotinia diseases, as well as consider the fungicide resistance and chemical residues, strategy of which plant nutritional regulation, as an eco-friendly approach, is gaining much significance. Selenium (Se), as a beneficial microelement for plant, has been manifested to be effective in inhibiting the mycelial growth of S.sclerotiorum in our previous study. In the present study, we observed that Se (both selenate and selenite) inhibited the formation of sclerotia, which is an important life form in the disease cycle of S. sclerotiorum. And the inhibition ratios of number of sclerotia in treatments of Se(VI)5.0 and Se(IV)5.0 were 54.55% and 43.84%, respectively; the inhibition ratios of weight of sclerotia in treatments of Se(VI)5.0 and Se(IV)5.0 were 42.29% and 25.67%, respectively. Results suggested that Se inhibited mycelial growth, severely damaged sclerotial ultrastructure, reduced the capacity of acid production, decreased superoxide dismutase (SOD) and catalase (CAT) activities, increased the content of hydrogen peroxide (H2O2) and superoxide anion (O2-) in mycelium, and all of these resulted in the reduction in sclerotial formation. Further studies revealed that Se application in medium increased Se concentration in sclerotia and thus inhibited sclerotial germination. Moreover, the pathogenicity of mycelia germinating from sclerotia that pretreated with Se, decreased significantly to rape leaves. These findings broadened our understanding of Se application in plant protection, as well as provided evidences for developing environment-friendly fungicide for S. sclerotiorum control.

Alternative control of grape rots by essential oils of two Eucalyptus species.

BACKGROUND: Essential oils (EOs) are volatile natural compounds produced by plant secondary metabolism, and some of them exhibit antimicrobial activity. The objective of the present study was to determine the chemical composition the EOs of Eucalyptus staigeriana and Eucalyptus globulus, and their effect in vitro and in vivo against Botrytis cinerea and Colletotrichum acutatum, the most important fungal rot diseases of grapes. Moreover, grapes collected from field experiments were used to evaluate the impact of the alternative control on the alcoholic fermentation and wine composition. RESULTS: The major compound of E. staigeriana EO were citral 30.91% (19.74% geranial, 11.17% neral), 1.8-cineole (24.59%) and limonene (19.47%), while 1.8-cineole represented 68.26% of E. globulus EO. The two EOs showed in vitro antifungal activity against both pathogens. Eucalyptus staigeriana EO exhibited the highest activity inhibiting mycelial growth (MG) and conidial germination at 0.5 µL mL-1 . Moreover, this EO was able to reduce the incidence and severity of grey rot caused by B. cinerea and the severity of ripe rot caused by C. acutatum The alternative control did not significantly influence alcoholic fermentation, the physicochemical characteristics, and the volatile composition of wines. CONCLUSION: These results are promising and indicate that E. staigeriana EO might be further investigated as a natural alternative for the control of fungal rots on wine grapes. © 2019 Society of Chemical Industry.

Interdependent nitric oxide and hydrogen peroxide independently regulate the coix seed oil-induced triterpene acid accumulation in Ganoderma lingzhi.

Recent progress has been made in adding exogenous vegetable oils in culture media to promote bioactive metabolite production in several medicinal mushrooms, but the mechanism is still unclear. In this study, we found that the vegetable oil coix seed oil (CSO) could induce the biosynthesis of triterpene acids (TAs) and also significantly increase cytoplasmic nitric oxide (NO) and hydrogen peroxide (H2O2) concentrations in the mycelium of Ganoderma lingzhi. The change in TA biosynthesis caused by CSO could be reversed by adding NO scavenger or H2O2 scavenger, and adding NO scavenger or H2O2 scavenger resulted in the reduction of the cytoplasmic H2O2 or NO concentration under CSO treatment, respectively. Moreover, adding NO scavenger or H2O2 scavenger reversed TA biosynthesis, which could be rescued by H2O2 or NO donor, respectively. Taken together, our study indicated that both NO and H2O2 were involved in the regulation of TA biosynthesis, and CSO-activated NO and H2O2 were interdependent but independently regulated the TA biosynthesis under CSO treatment in G. lingzhi.

Exploring Ecological Alternatives for Crop Protection Using Coriandrum sativum Essential Oil.

Essential oils (EOs) are a natural source of active compounds with antifungal, antimycotoxigenic, and herbicidal potential, and have been successfully used in organic agriculture, instead of chemical compounds obtained by synthesis, due to their high bioactivity and the absence of toxicity. The aim of this study was to highlight the importance of Coriandrum sativum essential oil (CEO) as a potential source of bioactive constituents and its applications as an antifungal and bioherbicidal agent. The CEO was obtained by steam distillation of coriander seeds and GC-MS technique was used to determine the chemical composition. Furthermore, in vitro tests were used to determine the antifungal potential of CEO on Fusarium graminearum mycelia growth through poisoned food technique, resulting in the minimum fungistatic (MCFs) and fungicidal concentrations (MCFg). The antifungal and antimycotoxigenic effect of CEO was studied on artificially contaminated wheat seeds with F. graminearum spores. Additionally, the herbicidal potential of CEO was studied by fumigating monocotyledonous and dicotyledonous weed seeds, which are problematic in agricultural field crops in Romania. The in vitro studies showed the antifungal potential of CEO, with a minimum concentration for a fungistatic effect of 0.4% and the minimum fungicidal concentration of 0.6%, respectively. An increase in the antifungal effects was observed in the in vivo experiment with F. graminearum, where a mixture of CEO with Satureja hortensis essential oil (SEO) was used. This increase is attributed to the synergistic effect of both EOs. Moreover, the synthesis of deoxynivalenol (DON)-type mycotoxins was found to be less inhibited. Hence, CEO has shown an herbicidal potential on weed seeds by affecting inhibition of germination.

Effects of cold plasma, UV-C or aqueous ozone treatment on Botrytis cinerea and their potential application in preserving blueberry.

AIMS: This study aimed to compare the effects of cold plasma (CP), ultraviolet (UV-C) and aqueous ozone (AO) on Botrytis cinerea and explore their application in preserving blueberry. METHODS AND RESULTS: The effects of CP, UV-C or AO on B. cinerea were investigated. Results showed that three treatments effectively inhibited the growth of B. cinerea, increasing cell membrane penetrability and causing the leakage of cytoplasm and nucleic acid. Scanning electron microscopy showed that CP caused the mycelium fold and collapse depression; UV-C caused the mycelium shrivelled; mycelium treated with AO appeared to fold and break. In the in vivo test in blueberry, all treatments effectively inhibited the growth of micro-organisms, maintained qualities and enhanced antioxidant activities in blueberry during postharvest storage. CONCLUSION: Cold plasma, UV-C and AO effectively inhibited the growth of B. cinerea and significantly extended the shelf life of blueberry. Based on in vitro and in vivo tests, CP showed better effects to preserve blueberry compared with other treatments. SIGNIFICANCE AND IMPACT OF THE STUDY: Our findings revealed the effective mechanisms of CP, UV-C and AO to inhibit B. cinerea in vitro. CP exhibited better application potential to preserve fresh fruit than traditional sterilization methods such as UV-C and AO.

Dual Mode of Action of Grape Cane Extracts against Botrytis cinerea.

Crude extracts of Vitis vinifera canes represent a natural source of stilbene compounds with well characterized antifungals properties. In our trials, exogenous application of a stilbene extract (SE) obtained from grape canes on grapevine leaves reduces the necrotic lesions caused by Botrytis cinerea. The SE showed to possess a direct antifungal activity by inhibiting the mycelium growth. The activation of some grapevine defense mechanism was also investigated. H2O2 production and activation of mitogen-activated protein kinase (MAPK) phosphorylation cascades as well as accumulation of stilbenoid phytoalexins were explored on grapevine cell suspension. Moreover, the transcription of genes encoding for proteins affecting defense responses was analyzed on grapevine plants. The SE induced some grapevine defense mechanisms including MAPK activation, and the expression of pathogenesis-related (PR) genes and of a gene encoding the glutathione-S-transferase 1 ( GST1) . By contrast, treatment of grapevine leaves with SE negatively regulates de novo stilbene production.

Antifungal efficiency of wild plants against human-opportunistic pathogens.

BACKGROUND: Fungal infection with opportunistic fungi can cause a serious problem for immunocompromised persons such as organ-transplant recipients, cancer, and HIV/AIDS patients. Control of these organisms using natural products is an interesting strategy to avoid the use of heavy chemotherapy in patients. OBJECTIVE: This study aimed to use the extract of Forsskaolea tenacissima L. and Xanthium spinosum L. to suppress the growth of Candida albicans and Geotrichum candidum and to investigate their potential mode of action. MATERIALS AND METHODS: Different plant extracts were tested for their antifungal activity using disc diffusion method and their mode of action was explored using the scanning electron microscopy (SEM) and gas chromatography-mass spectrometry (GC-MS). RESULTS: The results showed that chloroform extract of X. spinosum was the most effective against G. candidum, inhibiting its growth at very low concentration (38µg/mL). Chloroform extract of F. tenacissima was the most effective against C. albicans, with a minimum inhibitory concentration of 39µg/mL. SEM demonstrated the fungitoxicity of the plant extracts against both pathogens. C. albicans treated with plant extract were invaginated and ruptured and the treated mycelia of G. candidum were distorted and squashed. GC-MS analysis showed that the chloroform extract of both plants had 13 different compounds. CONCLUSION: Due to these promising results, these extracts should be further investigated and tested on different strains of C. albicans and G. candidum towards validation of their efficacy as a natural drug.

Isolation and structural elucidation of antifungal compounds from Ryudai gold (Curcuma longa) against Fusarium solani sensu lato isolated from American manatee.

In a previous study, we reported that Curcuma longa strain Ryudai gold (RD) showed antifungal activity against Fusarium solani sensu lato (FSSL) among the different species and varieties of turmeric. The present study focused on isolation, identification and structural elucidation of antifungal compounds in RD. The ethyl acetate (EtOAc) fraction was eluted with n-hexane and EtOAc with gradually increasing the concentration of EtOAc (n-hexane:EtOAc; 100:0; 80:20; 60:40, 40:60, 20:80 and 0:100). The antifungal compounds were isolated from the most effective fraction by using silica gel, TOYOPEARL® HW-40F column, and high-performance liquid chromatography. Structural identification of the antifungal compounds was conducted using 1H NMR, 13C NMR, and liquid chromatography-tandem mass spectrometry. The MeOH extract of the rhizome of RD inhibited the growth of FSSL in a concentration-dependent manner. The EtOAc fraction of the MeOH extract of RD demonstrated the highest antifungal activity against FSSL. The purified antifungal compounds were turmeronol B (1), turmeronol A (2), (E)-α-atlantone (3), dihydrobisdemethoxycurcumin (4), demethoxycurcumin (5) and curcumin (6). These six compounds showed concentration-dependent antifungal activity against FSSL. The concentration required for 50% growth inhibition (IC50) of the four isolates of FSSL ranged from 116 to172, 127 to 185, 88 to 109, 90 to 112, 74 to 80 and 63 to 68 µM/L for turmeronol B, turmeronol A, (E)-α-atlantone, dihydrobisdemethoxycurcumin, demethoxycurcumin and curcumin, respectively. These results suggested that RD contained potential antifungal compounds that could be useful to control FSSL. The isolated compounds of RD can be a good source of natural antifungal agents or the lead compounds for the development of new synthetic drugs.