In Vitro Studies of Antifungal Activity of Colloidal Silver against Important Plants Pathogens

Colloids and especially silver are increasingly used in a variety of worldwide applications because of their potential antimicrobial activity and their plasmotic and conductivity properties. This research reports the fungitoxic properties of colloidal silver on mycelial growth of important plant pathogens: Alternaria brassicicola, Botrytis cinerea, Aspergillus flavus, Aspergillus niger, Fusarium culmorum, Fusarium oxysporum, Penicillium digitatum and Sclerotinia sclerotiorum. Although variable responses towards each compound were observed within the species the results revealed a clear reaction to limiting mycelium growth relative to various concentration of Colloidal silver (CS). Results were expressed as effective concentrations which inhibit mycelial growth by 50% and 90% respectively (EC50 and EC90). Efficiency of colloidal silver on mycelial growth inhibition of different isolates based on EC50 have the following values: 3.69 ppm for Alternaria brassicicola, 7.32 ppm for Botrytis cinerea, 18.21 ppm for Aspergillus flavus, 10.43 ppm for Aspergillus niger, 11.99 ppm for Fusarium culmorum, 12.27 ppm for Fusarium oxysporum, 10.82 ppm for Penicillium digitatum and 6.34 ppm for Sclerotinia. According to the obtained results the antifungal activity of colloidal silver particles as biocide has potential for using it as a non-aggressive treatment in horticulture and sustainable horticulture

Investigaţii pentru determinarea practică a ph-ului în sol pentru un sistem de irigaţii

A method and a device based on galvanic cell for practical determiation of soil quality deterioration under the action of water, nutrients, and pesticides are analyzed. The novelty lies in facilitating the input of measured data directly into an automated irrigation system via wireless communication. pH offsetting with temperature is provided. The research was aimed to investigate materials for electrodes construction and to calibrate the device with proper electrodes using known pH solution

Revue Analytique des Maladies Fongiques Affectant la Production du Haricot Vert (Phaseolus vulgaris)

Le haricot vert (Phaseolus vulgaris), largement consommé au Bénin et en Afrique de l’Ouest offre des avantages nutritionnels significatifs en tant que source potentielle de protéines, de calories, de vitamines et de minéraux, suscitant un intérêt pour le marché mondial. Cependant, malgré ses atouts, sa production est confrontée à diverses contraintes. Cette revue analytique, basée sur des données de la littérature nationale et internationale dresse un état des lieux des contraintes biotiques liées a la production du haricot vert. De façon spécifique, la revue a permis d’inventorier toutes les maladies fongiques du haricot vert et d’identifier leurs méthodes de gestion. La rédaction de cette revue s’appuie sur une recherche bibliographique dans diverses bases de données de recherches. Les critères d’inclusion se concentrent sur les maladies fongiques et leurs méthodes de contrôle, excluant les données relatives aux maladies bactériennes, virales ainsi qu’aux bioagresseurs tels que les insectes, les acariens et les nématodes. Les résultats de cette étude révèlent que les agents phytopathogènes sont prédominants, entrainant des pertes de rendement pouvant atteindre 100%. L’application des mesures prophylactiques, combinée à l’intégration des méthodes de luttes biologique, culturale, génétique et chimique offrent une gestion efficace des agents phytopathogènes. En conclusion, des perspectives de recherches, axées sur l’épidémiologie et les méthodes de luttes, sont nécessaires pour réduire la dépendance du Bénin à l’importation venant de pays voisins.   The Green beans (Phaseolus vulgaris) widely consumed in Benin and West Africa, offers significant nutritional benefits as a potential source of protein, calories, vitamins and minerals, generating interest in global market. However, despite its advantages, its production faces various constraints. This analytical review, based on data from national and international literature, provides an overview of the biotic constraints related to green beans production. Specifically, the review inventoried all fungal diseases of green beans and identified their management methods. The compilation of this review relies on a bibliographic search in various research databases. Inclusion criteria focused on fungal diseases and their control methods excluding data on bacterial and viral diseases and bio-aggressors such as insects, mites and nematodes. The results of this study reveal that phytopathogenic agents are predominant, leading to yield losses of up to 100%. The application of prophylactic measures, combined with the integration of biological, cultural, genetic, and chemical control methods, offers effective management of phytopathogenic agents. In conclusion, research perspectives focused on epidemiology and control methods are necessary to reduce Benin’s dependence on imports from neighboring countries

In vitro antifungal activity of chitosan-polyphenol conjugates against Phytophthora cinnamomi

Producción CientíficaPhytophthora cinnamomi is responsible for radical rot in a wide range of hosts, resulting in large economic and ecological losses worldwide. In Spain, it is responsible for diseases such as the oak decline or the chestnut blight. In this study, different polyphenol-stevioside inclusion compounds dispersed in a hydroalcoholic solution of chitosan oligomers have been investigated, with a view to their application as natural bioactive complexes to replace conventional systemic fungicides against this fungus. The polyphenols tested in vitro were curcumin, ferulic acid, gallic acid and silymarin. Three concentrations (125, 250 and 500 µg·mL−1) were assayed, with and without silver nanoparticles (AgNPs), and notable differences were found in the inhibition of mycelium growth, with EC50 and EC90 values ranging from 171 to 373.6 µg·mL−1, and from 446.2 to 963.7 µg·mL−1, respectively. The results obtained showed that the addition of AgNPs, despite their antimicrobial activity, did not always lead to synergies. In the case of P. cinnamomi, an unexpected antagonistic behavior was found for two of the polyphenols (curcumin and silymarin), while an additive behavior for ferulic acid and a synergistic behavior for gallic acid were attained. In view of their inhibitory power, the preparations based on ferulic acid with AgNPs and on silymarin without AgNPs are proposed for applications in crop and forests protection against P. cinnamomi.Junta de Castilla y León - Fondo Europeo de Desarrollo Regional (project VA258P18)Universidad de Zaragoza (project UZ2019-TEC-07

Responses to hydric stress in the seed-borne necrotrophic fungus Alternaria brassicicola

Alternaria brassicicola is a necrotrophic fungus causing black spot disease and is an economically important seed-borne pathogen of cultivated brassicas. Seed transmission is a crucial component of its parasitic cycle as it promotes long-term survival and dispersal. Recent studies, conducted with the Arabidopsis thaliana/A. brassicicola pathosystem, showed that the level of susceptibility of the fungus to water stress strongly influenced its seed transmission ability. In this study, we gained further insights into the mechanisms involved in the seed infection process by analyzing the transcriptomic and metabolomic responses of germinated spores of A. brassicicola exposed to water stress. Then, the repertoire of putative hydrophilins, a group of proteins that are assumed to be involved in cellular dehydration tolerance, was established in A. brassicicola based on the expression data and additional structural and biochemical criteria. Phenotyping of single deletion mutants deficient for fungal hydrophilin-like proteins showed that they were affected in their transmission to A. thaliana seeds, although their aggressiveness on host vegetative tissues remained intact

Actividad antifúngica contra Fusarium culmorum de los extractos de hojas de Stevia rebaudiana y sus combinaciones con extractos de semillas de Silybum marianum y Lycium barbarum

Fusarium culmorum es un hongo que produce la fusariosis (scab o FHB), una enfermedad que plantea un importante reto en la producción de cereales y conlleva notables implicaciones de seguridad alimentaria por la contaminación con micotoxinas (tricotecenos). Ocasionalmente, se desarrolla en almacén cuando las condiciones le son favorables (a bajas temperaturas y alta humedad) o si el grano ha sido secado insuficientemente y de forma rápida. En este estudio se ha evaluado in vitro el efecto antifúngico de los extractos de hojas de estevia, solos o en combinación con polifenoles (procedentes de semillas de cardo asnal, de semillas de goji o ácido gálico puro), contra este fitopatógeno. Se han ensayado distintas concentraciones, desde 31.25 µg·mL-1 a 1 mg·mL-1 y se han obtenido, para el tratamiento basado sólo en las hojas de estevia, concentraciones inhibitorias CE50 y CE90 de 112 y 283 µg·mL-1, respectivamente; y para los tratamientos basados en hojas de estevia y polifenoles, valores de CE50 y CE90 de 160 y 500 µg·mL-1, respectivamente. Estos resultados llevan a concluir que, aunque el comportamiento para las mezclas es no-sinérgico para este patógeno (la respuesta a la presencia de polifenoles es impredecible), la actividad antifúngica de las hojas de estevia (referida, principalmente a esteviósido como principio activo) es incuestionable. En consecuencia, se propone la aplicación de extractos de hojas de estevia para la protección contra la fusariosis de cosechas y del grano en almacenes

Estudio de la actividad antifúngica in vitro de materiales compuestos basados en complejos de inclusión de polifenoles contra Phytophthora cinnamomi

El hongo Phytophthora cinnamomi es responsable de la podredumbre radical en una amplia gama de hospedantes, produciendo grandes pérdidas económicas y ecológicas a nivel mundial. En el caso de España, es responsable de enfermedades como la ‘seca’ de la encina y el alcornoque, o la ‘tinta’ del castaño. En este estudio se han investigado diferentes compuestos de inclusión de polifenoles-esteviósido dispersados en una solución hidroalcohólica de oligómeros de quitosano, con aplicación como complejos naturales bioactivos para reemplazar a los fungicidas sistémicos convencionales. Los polifenoles ensayados in vitro han sido curcumina, ácido ferúlico, ácido gálico y silimarina. Se han ensayado tres concentraciones (125, 250 y 500 µg·mL−1), con y sin nanopartículas de plata (AgNPs), y se han encontrado diferencias notables en la inhibición del crecimiento del micelio, con valores de CE50 y CE90 que han oscilado entre 171 y 373,6 µg·mL−1, y entre 446,2 y 963,7 µg·mL−1, respectivamente, observándose un rendimiento superior de los preparados a base de ácido ferúlico con AgNPs y de silimarina sin nAg. Los resultados obtenidos ponen en evidencia que la adición de AgNPs, pese a su actividad antimicrobiana, no siempre da lugar a sinergismos. En el caso de P. cinnamomi, se ha encontrado un comportamiento antagonístico inesperado para dos de los polifenoles (curcumina y silimarina), un comportamiento aditivo para el ácido ferúlico y un comportamiento sinergístico para el ácido gálico. Los preparados referidos pueden ser prometedores para aplicaciones de protección de cultivos y masas forestales contra P. cinnamomi

The composting potential of the by-product marc resulting from the white and red winemaking process

The production of an organic fertilizer was carried out, from waste generated in the winemaking process of white (Riesling Italian-RI) and red (Cabernet Sauvignon-CS) grapes obtained from the vineyard of Pietroasa (Romania). The potential of the biotransformation process of by-product marc in an open pile in the autumn-winter season was controlled and the thermophilic phase reached average values of 60 ºC at a neutral pH which gives it suitable characteristics to be used as a soil fertiliser. The values of the germination index (GI) of Lepidium sativum L. seeds, using water dilutions from the RI and CS compost marc, demonstrated that there was no degree of phytotoxicity (average GI 144.2% and 139.8%, respectively). The compost marc microflora was represented by bacterial and fungal isolates belonging to genera Rhizopus (10%), Aspergillus (80%), and Penicillium (17%), compared to by-product marc that only present fermentation yeasts. The structure of the microorganism populations in the compost marc dried by lyophilisation showed an almost double number of CFUg-1 compared to the oven-dried compost. The presence of potential antagonistic microorganisms and the high number of CFUg-1, demonstrated that this compost can have a suppressive effect on soil pathogens in addition to its quality as a fertilizer

Isolation of 12 polymorphic microsatellite loci in the phytopathogenic fungus Alternaria brassicicola

International audienc

Silver Nanoparticles and Polyphenol Inclusion Compounds Composites for Phytophthora cinnamomi Mycelial Growth Inhibition

Phytophthora cinnamomi, responsible for “root rot” or “dieback” plant disease, causes a significant amount of economic and environmental impact. In this work, the fungicide action of nanocomposites based on silver nanoparticles and polyphenol inclusion compounds, which feature enhanced bioavailability and water solubility, was assayed for the control of this soil-borne water mold. Inclusion compounds were prepared by an aqueous two-phase system separation method through extraction, either in an hydroalcoholic solution with chitosan oligomers (COS) or in a choline chloride:urea:glycerol deep eutectic solvent (DES). The new inclusion compounds were synthesized from stevioside and various polyphenols (gallic acid, silymarin, ferulic acid and curcumin), in a [6:1] ratio in the COS medium and in a [3:1] ratio in the DES medium, respectively. Their in vitro response against Phytophthora cinnamomi isolate MYC43 (at concentrations of 125, 250 and 500 µg·mL−1) was tested, which found a significant mycelial growth inhibition, particularly high for the composites prepared using DES. Therefore, these nanocomposites hold promise as an alternative to fosetyl-Al and metalaxyl conventional systemic fungicides