Direct Antifungal Activity Research Articles

Direct antifungal activity of methyl salicylate on soft rot caused by Rhizopus stolonifer and its membrane targeting mechanism

Methyl salicylate (MeSA) plays a significant role in various physiological metabolic processes of plants, however, reports on the antifungal activity were rare. This study aimed to investigate the direct antifungal activity of MeSA against Rhizopus stolonifer and to explore its antifungal mechanism at the membrane targeting level. Our study demonstrated that MeSA had antifungal activity. MeSA inhibited the mycelial growth and spore germination of Rhizopus stolonifer, and acted on the plasma membrane, changed the integrity and permeability of the cell membrane, leaked cell contents, induced reactive oxygen species (ROS) accumulation, stimulated membrane lipid peroxidation, changed the morphology of the mycelium, and finally caused apoptosis. In addition, in vivo experiments, MeSA significantly delayed the occurrence of soft rot of various fruits and vegetables. The results indicated that MeSA has direct antifungal activity for Rhizopus stolonifer, and proposed its antifungal mechanism from membrane targeting.

A smooth vetch (Vicia villosa var.) strain endogenous to the broad-spectrum antagonist Bacillus siamensis JSZ06 alleviates banana wilt disease.

Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense Tropical Race 4 (Foc TR4), poses a significant threat to banana production globally, thereby necessitating effective biocontrol methods to manage this devastating disease. This study investigates the potential of Bacillus siamensis strain JSZ06, isolated from smooth vetch, as a biocontrol agent against Foc TR4. To this end, we conducted a series of in vitro and in vivo experiments to evaluate the antifungal activity of strain JSZ06 and its crude extracts. Additionally, genomic analyses were performed to identify antibiotic synthesis genes, while metabolomic profiling was conducted to characterize bioactive compounds. The results demonstrated that strain JSZ06 exhibited strong inhibitory activity against Foc TR4, significantly reducing mycelial growth and spore germination. Moreover, scanning and transmission electron microscopy revealed substantial ultrastructural damage to Foc TR4 mycelia treated with JSZ06 extracts. Genomic analysis identified several antibiotic synthesis genes, and metabolomic profiling revealed numerous antifungal metabolites. Furthermore, in pot trials, the application of JSZ06 fermentation broth significantly enhanced banana plant growth and reduced disease severity, achieving biocontrol efficiencies of 76.71% and 79.25% for leaves and pseudostems, respectively. In conclusion, Bacillus siamensis JSZ06 is a promising biocontrol agent against Fusarium wilt in bananas, with its dual action of direct antifungal activity and plant growth promotion underscoring its potential for integrated disease management strategies.

Lactic acid induced defense responses in tobacco against Phytophthora nicotianae

Induced resistance is considered an eco-friendly disease control strategy, which can enhance plant disease resistance by inducing the plant’s immune system to activate the defense response. In recent years, studies have shown that lactic acid can play a role in plant defense against biological stress; however, whether lactic acid can improve tobacco resistance to Phytophthora nicotianae, and its molecular mechanism remains unclear. In our study, the mycelial growth and sporangium production of P. nicotianae were inhibited by lactic acid in vitro in a dose-dependent manner. Application of lactic acid could reduce the disease index, and the contents of total phenol, salicylic acid (SA), jasmonic acid (JA), lignin and H2O2, catalase (CAT) and phenylalanine ammonia–lyase (PAL) activities were significantly increased. To explore this lactic acid-induced protective mechanism for tobacco disease resistance, RNA-Seq analysis was used. Lactic acid enhances tobacco disease resistance by activating Ca2+, reactive oxygen species (ROS) signal transduction, regulating antioxidant enzymes, SA, JA, abscisic acid (ABA) and indole-3-acetic acid (IAA) signaling pathways, and up-regulating flavonoid biosynthesis-related genes. This study demonstrated that lactic acid might play a role in inducing resistance to tobacco black shank disease; the mechanism by which lactic acid induces disease resistance includes direct antifungal activity and inducing the host to produce direct and primed defenses. In conclusion, this study provided a theoretical basis for lactic acid-induced resistance and a new perspective for preventing and treating tobacco black shank disease.

Soil amendments with nanoparticles control cucumber wilt caused by Fusarium oxysporium

Management of Fusarium wilt, a destructive plant disease, mainly relies on chemicals, but research on novel and eco-friendly methods is needed due to the hazardous effects of chemical pesticides. This study explored the soil application of zinc oxide nanoparticles (ZnONPs) to manage Fusarium wilt disease in cucumber plants. The antifungal activity of ZnONPs against in-vitro growth of Fusarium oxysporum was tested through food poisoning test on the potato dextrose agar medium. The in-vivo potential of NPs for managing Fusarium wilt was checked in pot experiment. In-vitro results confirmed the concentration-dependent in-vitro antifungal activity. The NPs application at 500 µg/ml and 600 µg/ml concentrations showed phytotoxicity and significantly inhibited seed germination and growth of cucumber plants. However, NPs at 300 µg/ml significantly suppressed the pathogenic effects of F. oxysporum on cucumber plants without any phytotoxic effect. The pathogen-inoculated cucumber plants grown in soil amended with NPs showed significantly enhanced growth, lower disease severity, and improved root physiology compared to untreated plants. The plants under NPs treatment showed higher chlorophyll and nitrogen content while decreased membrane permeability and malondialdehyde content. Along with direct antifungal activity, the application of NPs caused an increased expression of defense-related genes and higher activities of defense-related enzymes. These findings verified the efficiency of ZnONPs for suppressing Fusarium wilt disease in cucumber crops, thereby promoting a non-chemical and environmentally friendly approach to controlling Fusarium wilt disease.

Is Silver Addition to Scaffolds Based on Polycaprolactone Blended with Calcium Phosphates Able to Inhibit Candida albicans and Candida auris Adhesion and Biofilm Formation?

Candida spp. periprosthetic joint infections are rare but difficult-to-treat events, with a slow onset, unspecific symptoms or signs, and a significant relapse risk. Treatment with antifungals meets with little success, whereas prosthesis removal improves the outcome. In fact, Candida spp. adhere to orthopedic devices and grow forming biofilms that contribute to the persistence of this infection and relapse, and there is insufficient evidence that the use of antifungals has additional benefits for anti-biofilm activity. To date, studies on the direct antifungal activity of silver against Candida spp. are still scanty. Additionally, polycaprolactone (PCL), either pure or blended with calcium phosphate, could be a good candidate for the design of 3D scaffolds as engineered bone graft substitutes. Thus, the present research aimed to assess the antifungal and anti-biofilm activity of PCL-based constructs by the addition of antimicrobials, for instance, silver, against C. albicans and C. auris. The appearance of an inhibition halo around silver-functionalized PCL scaffolds for both C. albicans and C. auris was revealed, and a significant decrease in both adherent and planktonic yeasts further demonstrated the release of Ag+ from the 3D constructs. Due to the combined antifungal, osteoproliferative, and biodegradable properties, PCL-based 3D scaffolds enriched with silver showed good potential for bone tissue engineering and offer a promising strategy as an ideal anti-adhesive and anti-biofilm tool for the reduction in prosthetic joints of infections caused by Candida spp. by using antimicrobial molecule-targeted delivery.

THE INFLUENCE OF MEDICINAL AND AROMATIC PLANTS EXTRACTS ON THE ANTIFUNGAL EFFECT OF FLUCONAZOLE REGARDING C. ALBICANS AND C. TROPICALIS ISOLATED FROM PATIENTS WITH DENTURE STOMATITS

Candida albicans is one of the most common and virulent representatives of Candida fungi which causes fungal lesions of the mucous membranes predominantly in people with compromised immune system. Candida resistance to classical antifungals such as polyenes, azoles, allylamines is a serious practical problem. Imidazole and triazole are the most commonly used antifungal agents for candidiasis today. Their mechanism of action lies in the inhibition of ergosterol biosynthesis which is indispensable for maintaining the structural integrity of fungal cell membranes. Activation of elimination systems is often associated with changes in the structure of fungal membranes, leading to a decrease in the supply of azoles into the fungal cell Screening of antifungal activity and synergism of antifungal activity of 166 aqueous-ethanol plant extracts with Fluconazole in relation to 2 clinical strains of Candida fungi (C.) (C. albicans and C. tropicalis) with different mechanisms of azole resistance isolated from patients with prosthetic stomatitis was conducted by means of agar diffusion method. The expressed direct antifungal activity of extracts of Calendula officinalis L. inflorescences, flowers of Limonium platyphyllum Lincz., flowers of Grataegus monogyna Jacq., roots of Potentilla repens L., the grass of Melilotus albus Medik, leaves of Peucedanum ruthenicum Bieb, leaves of Rhus coriaria L. and aerial part of Polythridum commune Hedw was determined in reference to the tested strains. Synergism of antifungal action with 1/4, 1/8 and 1/32 of Fluconazole MIC (minimal inhibiting concentration) in relation to both test strains of yeast-like Candida fungi was demonstrated by the flowers of Calendula officinalis L, aerial part of Melilotus albus Medik. The main purpose of the screening was to discriminate extracts in order to select those that would be promising for further testing by a more accurate сheckerboard titration method. The efflux mechanism of resistance to triazoles (in C. tropicalis test strain) is more susceptible to modification by biologically active compounds of medicinal plants. Regarding C. albicans test strain which combines the efflux mechanism of resistance with mutation(s) of ergosterol biosynthesis enzymes, the modifying effect of plant extracts is much less frequent and less pronounced. Therefore, it may be assumed that mutations of ergosterol biosynthesis enzymes provide high stability of the phenotypic manifestation of Candida azole resistance. Should that be the case, determining the azole resistance mechanism of Candida clinical isolates may be important for clinical practice. Combination therapy is more beneficial than monotherapy because it may provide more effective destruction or suppression of pathogens. The combined action of synergistic agents is quite easy to achieve in case of localized superficial lesions (which occur on the mucous membranes of the prosthetic bed in candidal prosthetic stomatitis): for example, using a systemic antifungal agent and a topical agent that contains a modifier of resistance of plant origin fungi. Synergistic interactions will increase the therapeutic efficacy of drugs, reduce the likelihood of resistance occurrence or further development, and will reduce dose-related toxicity.

Cyclic Lipopeptides of Bacillus amyloliquefaciens DHA6 Are the Determinants to Suppress Watermelon Fusarium Wilt by Direct Antifungal Activity and Host Defense Modulation.

Fusarium wilt, caused by Fusarium oxysporum f. sp. niveum (Fon), poses a serious threat to watermelon productivity. We previously characterized six antagonistic bacterial strains, including DHA6, capable of suppressing watermelon Fusarium wilt under greenhouse conditions. This study investigates the role of extracellular cyclic lipopeptides (CLPs) produced by strain DHA6 in Fusarium wilt suppression. Taxonomic analysis based on the 16S rRNA gene sequence categorized strain DHA6 as Bacillus amyloliquefaciens. MALDI-TOF mass spectrometry identified five families of CLPs, i.e., iturin, surfactin, bacillomycin, syringfactin, and pumilacidin, in the culture filtrate of B. amyloliquefaciens DHA6. These CLPs exhibited significant antifungal activity against Fon by inducing oxidative stress and disrupting structural integrity, inhibiting mycelial growth and spore germination. Furthermore, pretreatment with CLPs promoted plant growth and suppressed watermelon Fusarium wilt by activating antioxidant enzymes (e.g., catalase, superoxide dismutase, and peroxidase) and triggering genes involved in salicylic acid and jasmonic acid/ethylene signaling in watermelon plants. These results highlight the critical roles of CLPs as determinants for B. amyloliquefaciens DHA6 in suppressing Fusarium wilt through direct antifungal activity and modulation of plant defense responses. This study provides a foundation for developing B. amyloliquefaciens DHA6-based biopesticides, serving as both antimicrobial agents and resistance inducers, to effectively control Fusarium wilt in watermelon and other crops.

Carvacrol exhibits direct antifungal activity against stem-end rot disease and induces disease resistance to stem-end rot disease in kiwifruit

Kiwifruit stem-end rot is a common post-harvest disease caused by Clonostachys rosea and Fusariam equiseti, which triggers rapid fruit decay and reduces the commodity value of the fruit. This study investigated the antifungal activity and mechanism of carvacrol against pathogens of kiwifruit stem-end rot and its ability to induce disease resistance in kiwifruit. The results showed that the minimum inhibitory concentration and minimum fungus concentration of carvacrol to Clonostachys rosea and Fusariam equiseti were 0.06 and 0.09 mg/mL, respectively. Carvacrol could significantly inhibit mycelial growth and spore germination. With the increase of carvacrol concentration, the release of nucleic acid, electrical conductivity, protein, soluble sugar, and lipid contents gradually increased. Propidium iodide staining showed that the membrane integrity of Clonostachys rosea and Fusariam equiseti mycelia treated with carvacrol was damaged. In addition, carvacrol treatment inhibited the spread of plaque diameter after inoculation with Clonostachys rosea and Fusariam equiseti, effectively improved the activities of disease-resistant enzymes during storage, promoted the accumulation of pathogenesis-related proteins chitinase and glucanase, and increased the content of total phenols and flavonoids. These results show the potential application of carvacrol to control kiwifruit stem-end rot disease.

The application of zinc oxide nanoparticles: An effective strategy to protect rice from rice blast and abiotic stresses

The causal agent of blast disease, the filamentous fungus Magnaporthe oryzae, leads to tremendous damage on rice production worldwide. Zinc oxide nanoparticles (ZnO NPs) have multi-functions in plant growth and antimicrobial activity. However, the effects of ZnO NPs on M. oryzae and disease resistance in rice are still unclear.Here, we showed that ZnO NPs have direct antifungal activity against M. oryzae by inhibiting its conidiation and appressorium formation. In addition, ZnO NPs significantly inhibit blast development and enhance basal resistance in rice by inducing ROS accumulation and expression of defense-related genes OsNAC4, OsPR10, OsKSL4, and OsPR1b. Furthermore, we showed that ZnO NPs treatment reduces ABA level in plant, leading to increased ROS accumulation and enhanced resistance against M. oryzae. Importantly, ZnO NPs treatment improves the tolerance of rice seedlings to osmotic and heat stresses.In conclusion, not only being an effective aid in fighting against blast disease, ZnO NPs also provides a novel strategy to enhance the tolerance of rice seedlings to abiotic stress.

Compatible Consortium of Endophytic Bacillus halotolerans Strains Cal.l.30 and Cal.f.4 Promotes Plant Growth and Induces Systemic Resistance against Botrytis cinerea.

Evaluating microbial-based alternatives to conventional fungicides and biofertilizers enables us to gain a deeper understanding of the biocontrol and plant growth-promoting activities. Two genetically distinct Bacillus halotolerans strains (Cal.l.30, Cal.f.4) were evaluated for the levels of their compatibility. They were applied individually or in combination under in vitro and greenhouse conditions, using seed bio-priming and soil drenching as inoculum delivery systems, for their plant growth-promoting effect. Our data indicate that application of Cal.l.30 and Cal.f.4 as single strains and as a mixture significantly enhanced growth parameters of Arabidopsis and tomato plants. We investigated whether seed and an additional soil treatment with these strains could induce the expression of defense-related genes in leaves of young tomato seedling plants. These treatments mediated a long lasting, bacterial-mediated, systemic-induced resistance as evidenced by the high levels of expression of RP3, ACO1 and ERF1 genes in the leaves of young tomato seedlings. Furthermore, we presented data showing that seed and soil treatment with B. halotolerans strains resulted in an effective inhibition of Botrytis cinerea attack and development on tomato leaves. Our findings highlighted the potential of B. halotolerans strains as they combine both direct antifungal activity against plant pathogens and the ability to prime plant innate immunity and enhance plant growth.

Enhancing tomato resistance by exploring early defense events against Fusarium wilt disease

Studying plant early immunity, such as the unique immune mechanisms against pathogens, is an important field of research. Tomato wilt resulting from the infection by Fusarium oxysporum f. sp. lycopersici (Fol) is an important soil-borne vascular disease. In this study, we challenged tomato plants with Fol for a time-course RNA sequencing (RNA-seq) analysis. The result indicated that phenylpropanoid and flavonoid pathway genes were significantly enriched during the early invasion stage. Further study revealed that the flavonoids galangin and quercetin could effectively inhibit Fol growth and enhance wilt resistance in tomato. Moreover, the genes involved in plant-pathogen interactions, the MAPK signaling pathway, and plant hormone signal transduction were significantly enriched. These genes were also involved in plant pattern-triggered immunity (PTI) and effector-triggered immunity (ETI) signaling pathways. Strikingly, the transcription levels of pathogen-related protein 1 (SlPR1) were dramatically increased at 2 days post Fol inoculation, implying that SlPR1 is important in early immunity in tomato. SlPR1 does not have direct antifungal activity. Instead, its C-terminal peptide CAPE1 could activate root defense responses, such as the reactive oxygen species (ROS) burst, salicylic acid (SA)/jasmonic acid (JA) production, and defense-related gene expression, which collectively increased tomato resistance to Fol infection. In addition, CAPE1 could induce systemic acquired resistance (SAR). Application of CAPE1 onto tomato leaves induced local resistance to the pathogen Botrytis cinerea and systemic resistance to Fol infection. These results advanced our understanding for the early immunity against Fol in tomato and provide potential strategy for tomato disease control.

Serendipita indica chitinase protects rice from the blast and bakanae diseases.

Serendipita indica, a multifunctional and useful endophyte fungus, has been intensively investigated in promoting plant growth and resistance towards biotic and abiotic stress. Multiple chitinases from microorganisms or plants have been identified to have a high antifungal activity as a biological control. However, chitinase of S. indica still needs to be characterized. We functionally characterized a chitinase (SiChi) in S. indica. The result showed that the purified SiChi protein confers high chitinase activity; importantly, SiChi inhibits the conidial germination of Magnaporthe oryzae and Fusarium moniliforme. After the successful colonization of rice roots by S. indica, both the rice blast disease and bakanae disease were significantly reduced. Interestingly, the purified SiChi could promptly induce rice disease resistance towards M. oryzae and F. moniliforme pathogens when sprayed on rice leaves. Like S. indica, SiChi could upregulate rice pathogen-resistant proteins and defense enzymes. In conclusion, chitinase of S. indica has direct antifungal activity and indirect induced resistance activity, implying an efficient and economic strategy for rice disease control by applying S. indica and SiChi.

Impact of palladium nanoparticles on plant and its fungal pathogen. A case study: Brassica napus-Plenodomus lingam.

The technological exploitation of palladium or palladium nanoparticles (PdNPs) is increasing, and their wider usage relates to an unwanted release of pollutants into the environment, raising public health concerns about the infiltration of palladium into the consumption chain. This study focuses on the effect of spherical gold-cored PdNPs of 50 ± 10 nm diameter stabilized by sodium citrate on the interaction between an oilseed rape (Brassica napus) and the fungal pathogen Plenodomus lingam. Pretreatment of B. napus cotyledons with PdNPs suspension 24 h before but not 24 h after inoculation with P. lingam resulted in a decrease in the extent of disease symptoms; however, this effect was caused by Pd2+ ions (35 mg l-1 or 70 mg l-1). Tests to determine any direct antifungal activity on P. lingam in vitro demonstrated that the residual Pd2+ ions present in the PdNP suspension were responsible for the antifungal activity and that PdNPs themselves do not contribute to this effect. Brassica napus plants did not show any symptoms of palladium toxicity in any form. PdNPs/Pd2+ slightly increased the chlorophyll content and the transcription of pathogenesis-related gene 1 (PR1), indicating the activation of the plant defence system. We conclude that the only toxic effect of the PdNP suspension was on P. lingam via ions and that PdNPs/Pd2+ did not have any deleterious effect on the B. napus plants.

Itraconazole and neutrophil interactions in the immune-inflammatory response of paracoccidioidomycosis using a murine air pouch infection model

Paracoccidioidomycosis (PCM) caused by Paracoccidioides brasiliensis (Pb), is a severe mycosis, prevalent in tropical countries. The presence of polymorphonuclear neutrophils (PMN) in lesions is conspicuous, indicating their central role in innate immunity through the direct killing of Pb and the production of cytokines that activate acquired immunity in the presence of itraconazole (Itra). The toxicity and direct antifungal activity of Itra on Pb in splenocyte co-cultures were evaluated in vitro. Itra showed no toxic effect but marked antifungal activity against Pb. Purified PMN were obtained by the subcutaneous (SC) injection of Pb into mice. Results showed the effect of Itra on the size of the air pouch produced, the cellular population that migrated to the infection site, protein, and mitochondrial metabolism patterns, production of ROS an NO, and the number of cytokines synthesized. Lower doses (3 and 10 mg/kg) of Itra did not affect the cellular profile but led to a lower influx of viable more active PMN, and increased production of ROS and proteins. At a dose of 50 mg/kg the PMN profile remained unchanged along with all other parameters analyzed remained unaltered. Decreases in most cytokine levels were inversely proportional to the Itra concentration. Lower Itra concentrations may elicit activation of the immune response because the combined effects of therapy and immune response are needed, while the higher dose does not require it. Itra also promotes the activation of the cytokines which elicit PMN activation and consequently the resolution of Pb18 infection in the air pouch.

SCREENING OF MEDICINAL AND AROMATIC PLANTS EXTRACTS FOR THE SYNERGISM WITH FLUCONAZOLE AGAINST CANDIDA ALBICANS AND CANDIDA TROPICALIS FUNGI ASSOCIATED WITH DENTURE STOMATITIS.

The aim: To conduct a primary screening of the ability of aqueous-ethanol extracts of medicinal plants to enhance the effect of fluconazole against resistant strains of Candida sp. associated with denture stomatitis, to justify the potential use of combined antifungal therapy. Materials and methods: 40 biochemical tests using the VITEK 2 system with the use of VITEK 2 YST ID card (Biomerieux, France). The computer programs UTHSCSA ImageTool 2.0 and Microsoft Office Excel 2003 were used for statistical processing of the results. Results: 114 extracts out of 166 studied ones (68.7 « 0.28%) showed direct antifungal activity in relation to C. tropicalis strain, 74 extracts (44.6 « 0.30%) turned out to be highly active (d IZ > 10 mm). Only 50 extracts out of 166 studied ones (30.1 « 0.28%) showed antifungal activity against C. albicans strain, 26 extracts (15.7 « 0.22%) were highly active (d IZ > 10 mm). Significant direct antifungal activity both against C. albicans strain and C. tropicalis strain was demonstrated by the extracts of the leaves of Sophora japonica, thallus of Mnium cuspidatum Hedw. (M.silvaticum Lindb.), herbs of Euphorbia amygdaloides L., Lathyrus niger (L.) Bernh., Betonica officinalis L. s. l., flowers of Primula officinalis Hill., roots of Scrophularia nodosa L. Conclusions: 1. Aqueous-ethanolic extracts of medicinal and aromatic plants of Ukrainian flora have direct antifungal activity against azole resistant C. albicans and C. tropicalis (44,6«0,30% and 15,7«0,22% of tested extracts respectively) associated with denture stomatitis as well restore their sensitivity to fluconazole (44,6«0,30% and 15,7«0,22% of extracts respectively).

Suppression of dry root rot disease caused by Rhizoctonia bataticola (Taub.) Butler in chickpea plants by application of thiamine loaded chitosan nanoparticles.

The present study evaluated the effect of thiamine loaded chitosan nanoparticle (TChNp) on chickpea plant growth under greenhouse condition. TChNp treated plants showed increased number of leaves, branches, shoot/root length, number of secondary roots and plant dry weight. Enhanced nodulation with larger nodules was observed in TChNp treated chickpea plants. A significant increase in the number of flowers, pods and grain yield was observed in the TChNp treated chickpea plants compared to the chitosan and untreated control. The TChNps showed direct antifungal activity towards Rhizoctonia bataticola as evidenced by in vitro and SEM analyses, which might be due to the solubility and size of the nanoparticle. TChNps treated chickpea plants challenged with R. bataticola showed significant reduction in plant mortality compared to infected untreated control under pot condition. These results indicate the potential of the TChNps in enhancing the yield and suppressing the dry root rot disease in chickpea.

Antimicrobial peptide CB-M exhibits direct antifungal activity against Botrytis cinerea and induces disease resistance to gray mold in cherry tomato fruit

Gray mold is a common postharvest disease caused by Botrytis cinerea that causes fruit decay and reduces fruit storage quality. In this study, the antifungal activity of antimicrobial peptide CB-M against B. cinerea and its mechanism of action, as well as the ability of CB-M to induce disease resistance in cherry tomato fruit, were investigated. CB-M had a strong inhibitory effect on spore survival and mycelial growth of B. cinerea, and these effects were enhanced with increased CB-M concentration. Moreover, significant leakages of cellular constituents and fluorescence microscopy assay confirmed that CB-M treatment could destroy the cell membrane integrity of B. cinerea. Scanning electron microscopy observations further demonstrated obvious distortion and shriveling of B. cinerea hyphae. Gel retardation and SDS-PAGE assay showed that CB-M could likely bind to cellular DNA and degrade/inhibit protein synthesis in B. cinerea. Furthermore, preincubation with CB-M before pathogen inoculation significantly decreased lesion diameter and incidence of gray mold caused by B. cinerea in tomato, cherry tomato, and grape fruit throughout whole storage time. Cherry tomato was used to explore the ability of CB-M to induce gray mold resistance, and the results showed that CB-M preincubation enhanced the activities of superoxide dismutase, peroxidase, and catalase, accelerated the accumulation of pathogenesis-related proteins, flavonoids, and total phenolics, and increased the activities of β-1,3-glucanase, chitinase, and phenylalanine ammonia-lyase during storage. These results indicated that CB-M is a good substitute for fungicides and has excellent prospects for controlling postharvest gray mold in horticultural crops.

24-epibrassinolide enhances mango resistance to Colletotrichum gloeosporioides via activating multiple defense response

Brassinosteroids (BRs) are natural steroidal phytohormones that regulate many essential processes of plant growth, development and responses to stress. However, the role of BRs in the defense response against Colletotrichum gloeosporioides in mango fruit remains largely unknown. This study investigated the resistance against C. gloeosporioides and the possible mechanisms of exogenous 24-epibrassinolide (EBR) in mango fruit. Results showed 1 μmol L−1 EBR effectively reduced the disease incidence and disease severity on mango fruit after inoculating with C. gloeosporioides. However, EBR had no direct antifungal activity against C. gloeosporioides in vitro test. EBR significantly improved the activities of phenylalanine ammonia-lyase (PAL), peroxidase (POD), chitinase (CHT), cinnamate-4-hydroxylase (C4H), β-1,3-glucanase (GLU) and 4-hydroxycinnamate CoA ligase (4CL), as well as the accumulation of flavonoids, lignin and total phenolics in mango fruit. EBR treatment also increased hydrogen peroxide (H2O2) content in mango fruit at early storage stage after inoculation, while increased catalase (CAT), ascorbate peroxidase (APX) and superoxide dismutase (SOD) activities with low reactive oxygen species (ROS) level in later storage stage. Besides, EBR treatment markedly reduced the changes in pectin methylesterase (PME) and polygalacturonase (PG) activities, which slowed down the hydrolysis of pectin, thus maintaining cell wall integrity. The principal component analysis indicated that EBR treatment was strongly associated with the increase of defense enzyme activities and metabolite contents and the inhibition of pectin hydrolysis. These results indicated that exogenous EBR could be a promising strategy to increase resistance against C. gloeosporioides in mango fruit by improving the defense responses against pathogens.

Antifungal Activity of Copper Oxide Nanoparticles against Root Rot Disease in Cucumber.

Metal oxide nanoparticles have recently garnered interest as potentially valuable substances for the management of plant diseases. Copper oxide nanoparticles (Cu2ONPs) were chemically fabricated to control root rot disease in cucumbers. A scanning electron microscope (SEM), X-ray diffraction (XRD) and photoluminescence (PL) were employed to characterize the produced nanoparticles. Moreover, the direct antifungal activity of Cu2ONPs against Fusarium solani under laboratory, greenhouse, and field conditions were also evaluated. In addition, the induction of host-plant resistance by Cu2ONPs was confirmed by the results of enzyme activities (catalase, peroxidase, and polyphenoloxidase) and gene expression (PR-1 and LOX-1). Finally, the effect of Cu2ONPs on the growth and productivity characteristics of the treated cucumber plants was investigated. The average particle size from all the peaks was found to be around 25.54 and 25.83 nm for 0.30 and 0.35 Cu2O, respectively. Under laboratory conditions, the study found that Cu2ONPs had a greater inhibitory effect on the growth of Fusarium solani than the untreated control. Cu2ONP treatment considerably reduced the disease incidence of the root rot pathogen in cucumber plants in both greenhouse and field environments. Defense enzyme activity and defense genes (PR1 and LOX1) transcription levels were higher in cucumber plants treated with Cu2ONPs and fungicide than in the untreated control. SEM analysis revealed irregularities, changes, twisting, and plasmolysis in the mycelia, as well as spore shrinking and collapsing in F. solani treated with Cu2ONPs, compared to the untreated control. The anatomical analysis revealed that cucumber plants treated with Cu2ONPs had thicker cell walls, root cortex, and mesophyll tissue (MT) than untreated plants. Cucumber growth and yield characteristics were greatly improved after treatment with Cu2ONPs and fungicide. To the best of our knowledge, employing Cu2ONPs to treat cucumber rot root disease is a novel strategy that has not yet been reported.

Resistance Induction and Direct Antifungal Activity of Some Monoterpenes against Rhizoctonia solani, the Causal of Root Rot in Common Bean.

This study was conducted to evaluate eco-friendly control agents (carvone, cuminaldehyde, and linalool) against Rhizoctonia solani, which causes root rot disease either by induction of defense response or direct antifungal activity. The induction of resistance was examined by detecting the transcription of defense genes and the effect of the tested control agents on the growth and the yield of common bean plants. The growth of R. solani was significantly inhibited after treatment with the tested compounds compared to the untreated control under laboratory conditions. The disease severity of root rot was decreased in common bean plants treated with the tested compounds compared to untreated control plants under greenhouse conditions. Common bean plants treated with the tested control agents expressed defense genes (Phenylalanine ammonia lyase and β-1,3-Glucanase) involved in jasmonic acid (JA) and salicylic acid (SA) signaling pathways with 2–5 fold higher than the control. Treatment of common beans with the tested control agents and fungicide significantly improved the growth and yield characteristics of common bean. Therefore, the use of monoterpenes could be a novel strategy to control this pathogen and consider the first report.