Synthesis of Novel Thiazolyl Hydrazine Derivatives and Their Antifungal Activity

A series of novel thiazolyl hydrazine derivatives 3a–3o were synthesized and evaluated for their in vitro antifungal activity against six phytopathogenic strains, namely, Botryosphaeria dothidea (B. d.), Gibberella sanbinetti (G. s.), Fusarium oxysporum (F. o.), Thanatephorus cucumeris (T. c.), Sclerotinia sclerotiorum (S. s.), and Verticillium dahliae (V. d.), by the classical mycelial growth rate method. Biological assessment results showed that most of these target compounds showed good antifungal activity toward tested strains. Especially, compound 3l showed excellent antifungal activities against B. d. and G. s. with relatively lower EC50 values of 0.59 and 0.69 µg/mL, respectively, which were extremely superior to those of commercial fungicides fluopyram, boscalid, and hymexazol and were comparable to those of carbendazim. Given the excellent bioactivity of designed compounds, this kind of thiazolyl hydrazine framework can provide a suitable point for exploring highly efficient antifungal agents.

Assessment of lignocellulosic residues from Northern Patagonian Andes (Argentina) for cultivation of Pleurotus ostreatus

This work evaluated mycelial growth rate (Kr) and fruiting of two Pleurotus ostreatus commercial strains (A01, 129) on formulations composed of lignocellulosic residues from farming and agroindustry of Northern Patagonian Andes, and of woody materials from invasive plants. Rosehip fluffs (RF), rosehip woodchips (RWC), southern beech wood shavings (SBWS), wheat straw (WS), and willow woodchips (WWC) were used as base substrates, and brewing bagasse (BB) as an alternative supplement to wheat bran (WB). Kr was higher in WS-WB and WS-BB for both strains. Experiments in fruiting chambers showed biological efficiencies (BEs) above 40% in WS-BB (both strains) and WS-WB (strain 129). Formulations using RWC or WWC gave BEs under 40%, while those composed of SBWS or RF showed lower Kr and contamination by moulds. Medium-scale fruiting experiments using strain A01 showed the highest BEs in WS-BB and RWC-WB. These results suggest that WS is the best substrate for Pleurotus ostreatus culture, although scarce in Northern Patagonian Andes. Nevertheless, WWC and RWC are suggested as alternative substrates, while BB is cheap and abundant, suitable as an alternative supplement to WB.

Antagonism of Plant Pathogens by Calotropis procera

Phomopsis sojae and Sclerotinia sclerotiorum are responsible for stem and pod dryness and white mold in soybean. These pathologies directly affect the quality of seeds/grains and compromise the entire plant. The use of extracts from different plants has been the subject of research for the control of several phytopathogens. Calotropis procera is among botanical species that synthesize efficient compounds for biocontrol. In this context, the aim of this study was to evaluate the in vitro effect of C. procera aqueous extract on P. sojae and S. sclerotiorum. The experiment was carried out in completely randomized blocks in a 2 × 5 factorial scheme (two fungi and five extract concentrations 0%, 5%, 10%, 15% and 20%) with 4 replicates. C. procera aqueous extract concentrations were added to Petri dishes containing PDA. After 48 hours, the mycelial growth rate was evaluated. After seven days of incubation, the fungal colony area, sporulation, and germination of P. sojae and S. sclerotiorum were evaluated. There was significant interaction between fungi × extract concentrations (p < 0.05) for all variables analyzed. The mycelial growth rate of P. sojae was lower than that of S. sclerotiorum. The diameter of the P. sojae fungal colony was smaller than that of S. sclerotiorum when concentrations of 5%, 10% and 15% were used. As the extract concentration increased, fungi sporulation and germination reduced.

In vitro control of Botrytis cinerea and Penicillium italicum by antagonistic yeasts

Gray mold in grapes (caused by Botrytis cinerea) and blue mold in citrus (caused by Penicillium italicum) are post-harvest diseases that cause major losses in these crops. The control of these diseases is based on the use of synthetic chemical fungicides. The increase in regulatory policies and demand to reduce the application of pesticides, due to harmful effects on the environment and humans, have led to the search for more ecofriendly alternatives, such as biological control agents. Thus, the present work aims to verify the antagonistic potential of four yeast strains, Pichia caribbica (CCMA 0759), Hanseniaspora opuntiae (CCMA 0760), Pichia manshurica (CCMA 0762), and Lachancea thermotolerans (CCMA 0763), against of B cinerea and P. italicum. To assess the antagonism of volatile compounds, Petri plates with two divisions containing potato-dextrose-agar (PDA) were used by placing a fungal mycelial disc and yeast suspension (3.0 × 106 cells mL-1) on opposite sides of the plate. The colony diameter and mycelial growth rate index of the fungi were evaluated via comparisons with the control plate without yeast. For the evaluation of the antagonism of diffusible substances in the medium, yeasts were striated 3 cm from the center of the plates containing PDA. After 48 h, a mycelial disc of each phytopathogen was placed in the center of the plates. The colony growth, inhibition halo, and mycelial growth rate index were evaluated via comparisons with the control plate. All yeast strains showed an antagonistic effect on the mycelial growth of B. cinerea in both tests. In the volatile compounds test, H. opuntiae, L. thermotolerans, P. caribbica, and P. manshurica inhibited mycelial growth by approximately 82%, 75%, 72%, and 50%, respectively. In the antagonism test of the diffusible substances in the medium, P. caribbica and P. manshurica inhibited mycelial growth by 58% and 33%, respectively. However, these yeast strains did not show an antagonistic effect against P. italicum. Thus, all isolates demonstrated potential to be tested as biocontrol agents of gray mold in post-harvest grape fruits.

Morphological and Pathogenic Characterization of Sclerotium rolfsii, the Causal Agent of Southern Blight Disease on Common Bean in Uganda

Over the last 5 years, Southern blight caused by Sclerotium rolfsii Sacc. has superseded root rots caused by pathogens such as Fusarium and Pythium spp. as a major constraint of common bean (Phaseolus vulgaris L.) production in Uganda. Although S. rolfsii is prevalent in all bean-growing regions of Uganda, there is a lack of information about its diversity and pathogenicity to guide the development of effective management strategies. In total, 348 S. rolfsii isolates were obtained from bean fields in seven agroecological zones of Uganda, with the following objectives: to characterize their morphology, based on mycelial growth rate, mycelium texture, and number of sclerotia; and to determine the pathogenicity of 75 selected isolates on five common bean varieties in artificially inoculated soils in a screenhouse. We found that mycelial growth rate and the number of sclerotia produced on artificial media varied among agroecological zones but not within a zone. The five bean varieties tested were found to be susceptible to S. rolfsii, including varieties MLB49-89A and RWR719 that are resistant to Fusarium and Pythium root rots, respectively. Preemergence damping-off ranged between 0 and 100%, and disease severity index ranged between 4.4 and 100%. The widespread and high levels of S. rolfsii virulence on varieties of common bean indicate that management intervention is urgently required to help reduce losses incurred by Ugandan smallholder farmers. [Formula: see text] Copyright © 2020 The Author(s). This is an open access article distributed under the CC BY 4.0 International license .

Mycelial inhibition of Trichoderma spp. isolated from the cultivation of Pleurotus ostreatus with an extract of Pycnoporus sp.

Background and Aims: The production of edible fungi is affected by bacterial, fungal and viral diseases, which very often cause large losses. In the productionof mushrooms of the genus Pleurotus, the fungi of Trichoderma spp. represent a serious problem of contamination and although there are some chemical compoundsthat control the infection, they are not entirely safe for human consumption. As a consequence, alternatives are being searched for through biotechnology,such as the one presented in this paper.Methods: Strains of fungi of the genus Trichoderma were isolated from the substrate where Pleurotus ostreatus was being cultivated. These were identifiedmorphologically and molecularly, followed by tests to inhibit the growth of Trichoderma strains in both agar and wheat straw, using a cetonic extract of thedehydrated fruiting body of Pycnoporus sp.Key results: Two strains of Trichoderma (T. pleuroti and T. atrobrunneum, belonging to the clade of T. harzianum) were isolated from infected substrate obtainedin production modules of Pleurotus ostreatus located in Tlaquitenango and Cuernavaca, in the state of Morelos, Mexico. The effect of a cetonic extract of thefruiting body of Pycnoporus sp. on the mycelial growth of the isolated strains of Trichoderma was also evaluated, observing decrease in mycelial growth rate inPetri dish up to 72% and on lignocellulosic substrate both mycelial growth and sporulation were delayed up to 10 days.Conclusions: The extract of Pycnoporus sp. could be an alternative to control the infection by Trichoderma spp. in mushroom cultures of the genus Pleurotus.Key words: disease control, edible mushrooms, lignocellulosic substrate.

Synthesis and antifungal activities of 3-substituted phthalide derivatives

In order to obtain novel bioactive compounds with significant antifungal activities, two series of 3-substituted phthalide derivatives were designed and synthesized via reduction, bromine substitution, and etherification. In addition, the antifungal activities of all target compounds against nine phytopathogenic fungi in vitro were tested by using the mycelial growth rate method at the concentration of 50 μg mL−1. Preliminary bioassay tests showed that some compounds exhibited more potent antifungal activities as compared with hymexazol. The preliminary structure-activity relationships (SARs) of all target compounds were also investigated.

Manganese affects the growth and metabolism ofGanoderma lucidumbased on LC-MS analysis

BackgroundAs a metal-enriched edible fungus,Ganoderma lucidumis capable of adsorbing manganese effectively. And the manganese ion is demonstrated to play an important role in the synthesis of manganese peroxidase (Mnp) and other physiological activities duringG. lucidumgrowth. Recently, the influence of manganese on the metabolites ofG. lucidumfruiting bodies can be revealed through metabonomics technique.MethodsIn this study, we uncovered the changes between the control and 200 mg/kg Mn-treated fruiting bodies with liquid chromatography coupled to mass spectrometry (LC-MS).ResultsThe mycelial growth rate, dry yield, Mnp activity , total polysaccharide content, triterpenoid content, and total manganese content in the mature fruiting bodies ofG. lucidumchanged between the control and different Mn-treated groups. Based on LC-MS method, a total of 16 significantly different metabolites were obtained and identified, among which, five presented significantly down-regulated and 11 up-regulated in Mn-treated samples. The metabolites chavicol and palmitoylethanolamide were particularly significantly up-regulated, and were found the strong promotion relationship. Dependent on the MetPA database, four KEGG pathways were detected and glycerophospholipid metabolism was most impacted, in which, choline was involved in.DiscussionThe added manganese ion in the substrate enhanced Mnp activities, and consequently promoted the mycelial growth, yield , metabolites in the fruiting bodies including triterpenoids, total manganese, chavicol, etc. Our finding can provide a theoretical reference to regulation of manganese on the physiological metabolism ofG. lucidum.

Evaluation of Mango Peel Extracts on the in vitro Colletotrichum gloeosporioides Development

Aims: To evaluate the in vitro effect of mango peel extracts using different types of solvent and concentrations on the Colletotrichum gloeosporioides development. Study Design: Activities were aimed at evaluating the in vitro antifungal potential of mango peel extracts. Study Location and duration: The study was carried out at the Laboratory of Post-Harvest Pathology of Fruits and Vegetables - State University of Montes Claros and Laboratory of Natural Products, Department of Chemistry - Federal University of Lavras during October and December 2018. Methodology: ‘Palmer’ mango peel (Mangifera indica) was submitted to drying in oven and grinding. Subsequently, extracts were obtained in Soxhlet system, using methanol, ethyl acetate and hexane as solvents. The three extracts were tested in vitro at concentrations of 0.0; 0.25; 0.5; 1.0 and 2.0 mg/mL by adding them in culture medium against C. gloeosporioides, which was isolated from mango fruits with anthracnose symptoms. The effect of extracts and their respective concentrations on the mycelial growth rate and conidia production and germination was evaluated. The design was completely randomized in a 3 x 5 factorial arrangement with 5 replicates. Results: Increased extract concentrations caused reduction in the mycelial growth rate of the pathogen (R2 = 0.96). Both factors under study acted simultaneously in conidia production (P < 0.05), and the hexane extract presented better results for this analyzed variable. There was total germination inhibition (P < 0.05) when 1 mg/mL ethyl acetate extract and 2 mg/mL methanol and hexane extracts were used. Conclusion: Methanol, hexane and ethyl acetate mango peel extracts had inhibitory effect on the in vitro C. gloeosporioides development.