Natural Fungicides Research Articles

The effect of volatile compounds of Syzygium aromaticum flower buds against Aspergillus flavus growth on wheat grain at postharvest stage

Reducing the postharvest loss of cereal grains caused by deleterious fungi is critically important for the grain supply chain. Exploring antifungal constituents of plant volatile organic compounds (PVOCs) could promote the development of natural gaseous fungicides in controlling the decay of postharvest grains. In this study, PVOCs were extracted from clove ( Syzygium aromaticum L.) buds and the primary constituents thereof were investigated for their effect on Aspergillus flavus growth in media postharvest grains. Fumigation with clove buds’ volatiles effectively inhibited A. flavus proliferation in 20% moisture wheat grains under simulated storage conditions. Gas chromatography-mass spectrometry analysis revealed that eugenol and caryophyllene were the two main constituents of clove bud volatiles (49.80% and 36.68%, respectively). An antifungal assay demonstrated that eugenol was responsible for the antifungal activity of clove bud volatiles against A. flavus. Eugenol can completely inhibit A. flavus growth at 0.12 and 0.40 μL/mL in vapor phase fumigation and liquid contact, respectively. The proliferation of A. flavus in 20% moisture wheat grains was completely controlled after fumigation with 600 μL/L eugenol vapor. Eugenol treatment can damage the membrane integrity of A. flavus mycelia, resulting in increased intracellular electrolyte leakage. The 38 metabolites in A. flavus hyphae exposed to 0.40 μL/mL eugenol were markedly differentially expressed and principally involved in the biosynthesis of glycerophospholipids, linoleic acid metabolism, fatty acid metabolism, sugar metabolism, and ATP-binding cassette transporters. Eugenol also causes phosphatidylserine eversion of the plasma membrane, increased reactive oxygen species, decreased ATP production, and damaged DNA in A. flavus . We propose that eugenol treatment can disrupt cell membrane integrity, fatty acid β -oxidation, and induce apoptosis in A. flavus . This study demonstrated the potential application of clove bud volatile organic compounds as biofumigants for postharvest grain management and provided new insights into the antifungal mechanism of the main constituents against A. flavus growth. • Clove volatiles from Syzygium aromaticum , L. could control Aspergillus flavus growth in wheat grains. • Eugenol and caryophyllene are the two main volatile components of clove determined by GC-MS. • Eugenol could inhibit the growth of A. flavus in vapor phase and liquid contact. • The antifungal actions of eugenol on A. flavus were studied by metabolomic and biochemical analyses. • Eugenol could be used as biofumigants for postharvest grain management.

Short Communication: Fungicidal effect of flax seed oil against several fungal strains

Abstract. Mir RA, Ahmad MK. 2023. Short Communication: Fungicidal effect of flax seed oil against several fungal strains. Asian J Nat Prod Biochem 21: 1-5. The plant world is provided with innate biologically active secondary metabolites, which regulate its defense mechanism. Chemical fungicides pose a great threat to the plant kingdom regarding disease resistance and phytotoxicity. Furthermore, chemical fungicides provide a short spectrum and poor control of plant pathogens. Seed oils have a great potential to act as a natural fungicide against several plant pathogens. The aim of this study was to evaluate the in vitro antifungal activity against eight fungal strains, Mucor mucedo, Penicillium expansum, Trichoderma viride, Trichoderma harzianum, Phytophthora crocatum, Aspergillus niger, Phytophthora infestans, and Venturia inaequalis by the poisoned food method. Antifungal activity was assessed regarding the inhibition percentage of radial growth on a solid medium (Potatoes Dextrose Agar/PDA). Flaxseed oil showed the highest (100%) antifungal activity against M. mucedo at a concentration of 5 ?L/mL, while moderate (53% and 60%) antifungal activity was recorded for P. expansum, and P. crocatum. However, linseed oil showed negative results against A. niger, T. viride, and T. harzianum. Thus, the results of the present study revealed that flaxseed oil has tremendous fungicidal activity and could become an alternative to synthetic fungicides for controlling certain dreadful plant fungal diseases.

Leaves of Chenopodium album as source of natural fungicides against Sclertium rolfsii

Series of experiments were conducted to identify the possible antifungal components of Chenopodium album leaves for the management of a highly destructive soil-borne fungal pathogen Sclerotium rolfsii. A 4% methanolic extract caused up to 82% reduction in biomass of the target organism. This extract was partitioned using solvents of variable polarities, and the obtained subfractions were evaluated for their activity against S. rolfsii. The best antifungal activity was detected for the ethyl acetate subfraction (60–74%) followed by n-hexane (51–69%), n-butanol (50–60%), chloroform (20–40%) while the aqueous sub-fraction had the lowest activity (9–35%) as detected by the decrease in biomass of the pathogen. Ethyl acetate and n-hexane sub-fractions were analyzed for their chemical constituents by GC–MS technique. Literature survey showed that among the identified compounds kitazin P, imidazole-4-carboxylic acid, 2-fluoro-1-methoxymethyl-, ethyl ester and 9,12,15-octadecatrienoic acid, 2,3-dihydroxypropyl ester, (Z,Z,Z)- had antifungal activities against other fungal species and could be responsible for control of S. rolfsii by methanolic extract in the present study.

Design and synthesis of novel benzoxazole/chromene-phthalide scaffolds hybrids as potential natural products-based fungicide

Phthalide, benzoxazole, and chromene are important heterocyclic skeletons with extensive biological activities. In order to develop novel potential antifungal agents, twenty-two benzoxazole/chromene-containing phthalide derivatives were prepared, and their fungicidal activity against nine common plants pathogenic fungi were evaluated in vitro. The EC50 values indicated that compound Z-4b displayed superior antifungal activity against P. oryzae (11.0 μg/mL), F. solani (8.5 μg/mL), P. capsici (27.8 μg/mL), V. mali (3.1 μg/mL) and A. brassicae (4.3 μg/mL) strains, which was more potent than the two commercialized fungicides hymexazol and chlorothalonil. In addition, the structure-activity relationship analysis demonstrated that the combination site of oxazolamide with phthalide has an important effect on antifungal activity. This research offers a potential compound for the development of novel agricultural fungicides.

Extracellular DNA of Fusarium oxysporum f. sp. cubense as a Priming Agent for Inducing the Resistance of Banana Plantlets

Fusarium wilt is one of the major causes of global losses in the banana industry. The application of extracellular DNA (eDNA) is explored as a natural fungicide. eDNA is categorized on the basis of the receiving cell’s perception, namely self and non-self. The application of self-eDNA in agriculture presents the potential for limiting the growth of pathogens, while non-self-eDNA, as a vaccine for plants. This study evaluated whether the eDNA from Fusarium oxysporum f. sp. cubense (Foc) could limit the growth of Foc itself (self-inhibition test) while increasing the resistance of banana plant (priming test). A self-inhibition test showed that the administration of 400 and 800 μg mL−1 eDNA inhibited Foc TR4 spore germination. A priming test was carried out on banana plantlets in the interaction medium containing eDNA Foc TR4 suspension with final concentrations of 40, 80, and 200 μg mL−1. After 24 h, the plantlets were infected with a suspension of 106 spore mL−1. Increased resistance was observed in plantlets treated with 200 μg mL−1 of Foc TR4 eDNA, as indicated by the decrease in leaf symptoms and rhizome discoloration. The accumulation of O2- and H2O2 was observed 24 h after priming as was a significant increase in the relative expression of CAT, PR1, and chitinase 1 genes on day 9 post-infection. In conclusion, eDNA Foc TR4 as a growth inhibitor of pathogen and a priming agent to the banana plantlets could be considered as a biofungicide candidate to induce the resistance of banana plants.

Antifungal activity of selected lactic acid bacteria from olive drupes

In this study, 16 Lactobacilli (LABs) isolated from the drupes of olive (Olea europaea) oil varieties were identified as Lactiplantibacillus plantarum (seven isolates), Pediococcus pentosaceus (six isolates), Enterococcus faecium (two isolates) and Streptococcus salivarius (a single isolate) by peptide mass fingerprinting and sequencing of the 16S rRNA. Antifungal activity of LABs and their cell-free fermentates (CFSs) against several plant pathogenic fungi and oomycetes (fungi sensu lato), including Alternaria, Aspergillus Colletotrichum, Penicillium, Plenodomus and Phytophthora, was evaluated in vitro using the culture overlaying and the agar diffusion tests. Minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC) were determined. LABs showed antifungal activity against the fungi sensu lato tested. The most noticeable inhibitory activity was shown by isolates of L. plantarum and P. pentosaceus against Fusarium oxysporum, Colletotrichum species and Penicillium nordicum. Chemical analysis revealed CFSs contained acid lactic and variable quantities of 14 diverse phenolic acids and 26 volatile organic compounds (VOCs). No obvious correlation was found between the metabolic profile of LABs and their antifungal efficacy. However, it is the first time that the potential of fermentates of LABs, recovered from drupes of olive oil varieties, as natural fungicides, was demonstrated.

Use of Yucca (Yucca schidigera) Extracts as Biostimulants to Promote Germination and Early Vigor and as Natural Fungicides.

Climate change is increasing drought and salinity in many cultivated areas, therefore threatening food production. There is a great demand for novel agricultural inputs able to maintain yield under the conditions imposed by the anthropogenic global warming. Biostimulants have been proposed as a useful tool to achieve this objective. We have investigated the biostimulant effect of different yucca (Yucca schidigera) extracts on plant growth at different stages of development under different abiotic stress conditions. The extracts were tested in the model plant Arabidopsis thaliana, and in three different crops; tomato (Solanum lycopersicum var microtom), broccoli (Brassica oleracea var. italica) and lettuce (Lactuca sativa var romana). We have found that the investigated extracts are able to promote germination and early vigor under drought/osmotic and salt stress induced either by sodium chloride or lithium chloride. This effect is particularly strong in Arabidopsis thaliana and in the Brassicaceae broccoli. We have also determined using antibiograms against the model yeast Saccharomyces cerevisiae that the evaluated extracts may be used also as a natural fungicide. The results in this report show that yucca extracts may be used to enhance early vigor in some crops and as a natural fungicide, providing a new and useful tool for farmers.

Toxicity and larvicidal activity on Aedes aegypti of citronella essential oil submitted to enzymatic esterification.

The essential oil of citronella (Cymbopogon winterianus) has several biological activities, among them the insect repellent action. Some studies showed that cinnamic acid esters can be applied as natural pesticides, insecticides and fungicides. In this context, the objective of the present work was to evaluate the production of esters from citronella essential oil with cinnamic acid via enzymatic esterification. Besides, the essential oil toxicity before and after esterification against Artemia salina and larvicidal action on Aedes aegypti was investigated. Esters were produced using cinnamic acid as the acylating agent and citronella essential oil (3:1) in heptane and 15 wt% NS 88011 enzyme as biocatalysts, at 70 °C and 150 rpm. Conversion rates of citronellyl and geranyl cinnamates were 58.7 and 69.0% for NS 88011, respectively. For the toxicity to Artemia salina LC50 results of 5.29 μg mL-1 were obtained for the essential oil and 4.36 μg mL-1 for the esterified oils obtained with NS 88011. In the insecticidal activity against Aedes aegypti larvae, was obtained LC50 of 111.84 μg mL-1 for the essential oil of citronella and 86.30 μg mL-1 for the esterified oils obtained with the enzyme NS 88011, indicating high toxicity of the esters. The results demonstrated that the evaluated samples present potential of application as bioinsecticide.

Metabolite Profiling and Bioassay-Guided Fractionation of Zataria multiflora Boiss. Hydroethanolic Leaf Extracts for Identification of Broad-Spectrum Pre and Postharvest Antifungal Agents

Hydroethanolic leaf extracts of 14 Iranian Zataria multiflora Boiss. populations were screened for their antifungal activity against five plant pathogenic fungi and metabolically profiled using a non-targeted workflow based on UHPLC/ESI-QTOFMS. Detailed tandem mass-spectrometric analyses of one of the most active hydroethanolic leaf extracts led to the annotation of 68 non-volatile semi-polar secondary metabolites, including 33 flavonoids, 9 hydroxycinnamic acid derivatives, 14 terpenoids, and 12 other metabolites. Rank correlation analyses using the abundances of the annotated metabolites in crude leaf extracts and their antifungal activity revealed four O-methylated flavones, two flavanones, two dihydroflavonols, five thymohydroquinone glycoconjugates, and five putative phenolic diterpenoids as putative antifungal metabolites. After bioassay-guided fractionation, a number of mono-, di- and tri-O-methylated flavones, as well as three of unidentified phenolic diterpenoids, were found in the most active subfractions. These metabolites are promising candidates for the development of new natural fungicides for the protection of agro-food crops.

Inhibitory effect of (E)-2-heptenal on Aspergillus flavus growth revealed by metabolomics and biochemical analyses

The prevention of fungal proliferation in postharvest grains is critical for maintaining grain quality and reducing mycotoxin contamination. Fumigation with natural gaseous fungicides is a promising and sustainable approach to protect grains from fungal spoilage. In this study, the antifungal activities of (E)-2-alkenals (C5-C10) on Aspergillus flavus were tested in the vapor phase, and (E)-2-heptenal showed the highest antifungal activity against A. flavus. (E)-2-Heptenal completely inhibited A. flavus growth at 0.0125 µL/mL and 0.2 µL/mL in the vapor phase and liquid contact, respectively. (E)-2-Heptenal can disrupt the plasma membrane integrity of A. flavus via leakage of intracellular electrolytes. Scanning electron microscopy indicated that the mycelial morphology of A. flavus was remarkably affected by (E)-2-heptenal. Metabolomic analyses indicated that 49 metabolites were significantly differentially expressed in A. flavus mycelia exposed to 0.2 µL/mL (E)-2-heptenal; these metabolites were mainly involved in galactose metabolism, starch and sucrose metabolism, the phosphotransferase system, and ATP-binding cassette transporters. ATP production was reduced in (E)-2-heptenal-treated A. flavus, and Janus Green B staining showed reduced cytochrome c oxidase activity. (E)-2-Heptenal treatment induced oxidative stress in A. flavus mycelia with an accumulation of superoxide anions and hydrogen peroxide and increased activities of superoxide dismutase and catalase. Simulated storage experiments showed that fumigation with 400 µL/L of (E)-2-heptenal vapor could completely inhibit A. flavus growth in wheat grains with 20% moisture; this demonstrates its potential use in preventing grain spoilage. This study provides valuable insights into understanding the antifungal effects of (E)-2-heptenal on A. flavus. KEY POINTS : • (E)-2-Heptenal vapor showed the highest antifungal activity against A. flavus among (C5-C10) (E)-2-alkenals. • The antifungal effects of (E)-2-heptenal against A. flavus were determined. • The antifungal actions of (E)-2-heptenal on A. flavus were revealed by metabolomics and biochemical analyses.

Lantadene A and boswellic acid isolated from the leaves of Lantana camara L. have the potential to control phytopathogenic Fusarium species

Phytopathogenic Fusarium species are restricting factors causing diseases and yield loss in crop production. As part of exploration for pesticides from medicinal plants, this study aimed to isolate and characterize bioactive compounds from Lantana camara L. and evaluate their efficiency against Fusarium phytopathogens. Phytochemical investigation of ethyl acetate leaf extract led to separation of lantadene A (22-angeloyloxy-9-hydroxy-3-oxo-olean-12-en-28-oic acid) and boswellic acid (11-keto-β-boswellic acid). The chemical structures of the aforementioned compounds were confirmed using physical properties, spectroscopic analysis, and published data. Lantadene A exhibited significant antifungal activity against F. subglutinans, F. proliferatum, F. solani, F. graminearum, and F. semitectum with minimum inhibitory concentration (MIC) less than or equal to 0.63 mg/mL. Boswellic acid exhibited strong activity (MIC = 0.63 mg/mL) against F. subglutinans and F. semitectum. In terms of their toxicity towards Raw 264.7 cells, lantadene A and boswellic acid recorded half-maximal inhibitory concentration values of 84.2 μg/mL and 186.6 μg/mL, respectively. Both lantadene A and boswellic acid had no phytotoxic effect against seed germination and seedling root length. Lantadene A and boswellic acid have strong potential to be further investigated as lead natural fungicides (biopesticides) to control Fusarium crop diseases.

Highly potent natural fungicides identified in silico against the cereal killer fungus Magnaporthe oryzae

Magnaporthe oryzae is one of the most notorious fungal pathogens that causes blast disease in cereals, and results in enormous loss of grain production. Many chemical fungicides are being used to control the pathogen but none of them are fully effective in controlling blast disease. Therefore, there is a demand for the discovery of a new natural biofungicide to manage the blast disease efficiently. A large number of new natural products showed inhibitory activities against M. oryzae in vitro. To find out effective biofungicides, we performed in silico molecular docking analysis of some of the potent natural compounds targeting four enzymes namely, scytalone dehydratase, SDH1 (PDB ID:1STD), trihydroxynaphthalene reductase, 3HNR (PDB ID:1YBV), trehalose-6-phosphate synthase, Tps1 (PDB ID:6JBI) and isocitrate lyase, ICL1 (PDB ID:5E9G) of M. oryzae fungus that regulate melanin biosynthesis and/or appresorium formation. Thirty-nine natural compounds that were previously reported to inhibit the growth of M. oryzae were subjected to rigid and flexible molecular docking against aforementioned enzymes followed by molecular dynamic simulation. The results of virtual screening showed that out of 39, eight compounds showed good binding energy with any one of the target enzymes as compared to reference commercial fungicides, azoxystrobin and strobilurin. Among the compounds, camptothecin, GKK1032A2 and chaetoviridin-A bind with more than one target enzymes of M. oryzae. All of the compounds except tricyclazole showed good bioactivity score. Taken together, our results suggest that all of the eight compounds have the potential to develop new fungicides, and remarkably, camptothecin, GKK1032A2 and chaetoviridin-A could act as multi-site mode of action fungicides against the blast fungus M. oryzae.

Antifungal Activity of Ginger Rhizome Extract against Fusarium solani

Fusarium solani is one of the most ruinous soil-borne pathogens and seriously affects crop yields and quality worldwide. Ginger is an important medicinal crop, and ginger rhizome extract (GRE) has been used as an alternative for chemical fungicides and bactericides. We investigated the fungistatic effect of GRE on F. solani and analyzed the chemical constituents of GRE using UPLC-MS/MS. Antifungal assay results showed that 20 mg/mL of GRE completely inhibited the growth of F. solani. Morphological analysis revealed that GRE destroyed the morphology and structure of mycelia, thus inhibiting mycelial growth. Furthermore, GRE suppressed the activities of cell wall-degrading and cellular respiratory-related enzymes and decreased the content of fusaric acid, which reduced or even abrogated the infection ability of F. solani. UPLC-MS/MS analysis showed that GRE constituents belonged to eight categories, among which phenolic acids were the highest in content (46.29%) and tannins were the lowest in content (0.06%). When the antifungal activities of major phenolic and flavonoid compounds were evaluated, 4.0 mg/mL 4-hydroxybenzaldehyde and 15.0 mg/mL quercetin were found to completely inhibit F. solani growth. These results highlight GRE as an excellent source of antifungal compounds and suggest the possibility of using 4-hydroxybenzaldehyde and quercetin as natural fungicides to control crop diseases.

Phytochemical composition, antioxidant, and antifungal activity of essential oil from Myrtus Communis, L

Myrtus communis. L, essential oil is considered a source of biologically active compounds. In our present study, we tried to determine the chemical composition of this oil by GS/MS after their extraction by steam distillation and to determine their antioxidant and antifungal activity. In the tested oil GC/MS, twenty-three components were identified, which represented 99.99 % of the total detected constituent. The major components of the leaves were 1.8 Cineol (41.24 %), d-Limonene (15.37 %), α-pinene (15.22 %), and Myrtenyl acetate (14.35 %). Other components were present in amounts less than 4 %. Our essential oil presents low antioxidant power, on the other hand, it has presented very high antifungal power, Penicillium digitatum ID = 53.67 mm, MIC = 0.5 μL/mL, MIF = 1 μL/mL, Aspergillus Niger ID = 49 mm, MIC = 0.5 μL/mL. Indeed, the results obtained in this work have allowed us to recommend the essential oil of Myrtus communis. L in the field of biotechnology as a natural fungicide.

Evaluation of Natural Antifungal Compounds from Artemisia afra and its Effectiveness on Prevention of Aflatoxins

Artemisia afra is a medicinal plant with antimicrobial activities, known to treat tuberculosis, measles, cough, and influenza. In consequence, its applications have increasingly become pivotal to control various microbes which cause different diseases. This study therefore, evaluated the chemical composition and the antifungal activity of A. afra essential oil. The extraction of essential oil was done using steam distillation. The essential oil chemical composition was analysed by GC-MS. The analysis revealed 19 compounds from A. afra. The main compounds were borneol (71.529%), terpinen-4-ol (8.582%), β-thujone (3.283%), β-terpineol (2.590%), α-terpineol (1.791%), chrysanthenone (1.507%), myrtenal (1.393%), eucalyptol (1,8-cineole) (1.263%), cis-sabinene hydrate (1.172%) and trans-carane, 4,5-epoxy (1.088%). The growth and aflatoxin production inhibitions against A. flavus were determined via antifungal and antiaflatoxigenic bioassays of the A. afra essential oil at the concentration range of 10–50 µL/mL using a poisoned-food method. The quantification of the aflatoxins production was carried out using high-performance liquid chromatography. The antifungal activity of A. afra essential oil was effective against A. flavus with growth inhibition of 99.97–99.99% and controlled aflatoxins production by 99.25–99.63%. The results indicated that A. afra essential oil can become an alternative natural fungicide for the control of A. flavus growth and aflatoxins production.
 Keywords: Artemisia afra; essential oil; A. flavus; aflatoxins; GC-MS

Potential Biochemical Pesticide-Synthesis of Neofuranocoumarin and Inhibition the Proliferation of Spodoptera frugiperda Cells through Activating the Mitochondrial Pathway.

Furanocoumarins, the secondary metabolites of plants, are considered to be natural insecticides and fungicides because they prevent the invasion of plant pathogenic microorganisms and the predation of herbivorous insects. In this study, novel 2-arylfuranocoumarin derivatives were designed to synthesize by condensation, esterification, bromination, and Wittig reaction. The results showed an excellent photosensitive activity of 2-thiophenylfuranocoumarin (I34). Cell Counting Kit-8 detected that I34 could inhibit the proliferation of Spodoptera frugiperda (Sf9) cells in a time- and concentration-dependent manner under ultraviolet A (UV-A) light for 3 min. The inverted microscope revealed that cells treated with I34 swelled, the membrane was ruptured, and apoptotic bodies appeared. The flow cytometry detected that I34 could induce apoptosis of Sf9 cells, increase the level of intracellular reactive oxygen species (ROS), decrease the mitochondrial membrane potential, and block cell cycle arrest in the G2/M phase. Transmission electron microscopy detected cell mitochondrial cristae damage, matrix degradation, and mitochondrial vacuolation. Further enzyme activity detection revealed that the enzyme activities of apoptosis-related proteins caspase-3 and caspase-9 increased significantly (p < 0.05). Finally, Western blotting analysis detected that the phosphorylation level of Akt and Bad and the expression of the apoptosis inhibitor protein Bcl-XL were inhibited, cleaved-PARP and P53 were increased, and cytochrome C was released from the mitochondria into the cytoplasm. Moreover, under UV-A irradiation, I34 promoted the increase in ROS in Sf9 cells, activated the mitochondrial apoptotic signal transduction pathway, and finally, inhibited cell proliferation. Thus, novel furanocoumarins exhibit a potential application prospect as a biochemical pesticide.

Discovery of Niphimycin C from Streptomyces yongxingensis sp. nov. as a Promising Agrochemical Fungicide for Controlling Banana Fusarium Wilt by Destroying the Mitochondrial Structure and Function.

Banana Fusarium wilt caused by Fusarium oxysporum f. sp. cubense (Foc) is the most destructive soil-borne fungal disease. Tropical race 4 (Foc TR4), one of the strains of Foc, can infect many commercial cultivars, which represents a threat to global banana production. Currently, there are hardly any effective chemical fungicides to control the disease. To search for natural product-based fungicides for controlling banana Fusarium wilt, we identified a novel strain Streptomyces yongxingensis sp. nov. (JCM 34965) from a marine soft coral, from which a bioactive compound, niphimycin C, was isolated using an activity-guided method. Niphimycin C exhibited a strong antifungal activity against Foc TR4 with a value of 1.20 μg/mL for EC50 and obviously inhibited the mycelial growth and spore germination of Foc TR4. It caused the functional loss of mitochondria and the disorder of metabolism of Foc TR4 cells. Further study showed that niphimycin C reduced key enzyme activities of the tricarboxylic acid (TCA) cycle and the electron transport chain (ETC). It displayed broad-spectrum antifungal activities against the selected 12 phytopathogenic fungi. In pot experiments, niphimycin C reduced the disease indexes in banana plantlets and inhibited the infection of Foc TR4 in roots. Hence, niphimycin C could be a promising agrochemical fungicide for the management of fungal diseases.

Antifungal Activity of Essential Oil Extracted from &lt;i&gt;Melaleuca alternifolia&lt;/i&gt; against Pathogenic Fungi on Mango (&lt;i&gt;Mangifera indica &lt;/i&gt;L.) for Mango Postharvest Application

An infection by pathogenic fungi is one of the major problem in post-harvest stage of mangoes. Therefore, the extraction of essential oil from Melaleuca alternifolia is being tested as a natural fungicide for controlling fungus infections of selected mangoes locally known as susu mango. The extraction was performed using Solvent-Free Microwave Assisted Extraction with a yield of 0.57% concentration. The inhibitory effect of this essential oil against isolated fungi from mango was investigated through in-vitro and in-vivo analyses. Distilled water was used as a negative control while chemical fungicide (Globus 5.5) was used as a positive control in the analyses. The mycelial growth inhibition of the extracted essential oil for poisoned food test and disc diffusion method showed 62.50 ± 0.49% and 59.70 ± 0.30% respectively for in-vivo experiment which used unwounded and artificially wounded mangoes. The result also demonstrated that the essential oil applied on the mangoes could decrease the disease incidence from 100% to 61.33% for up to 10 days incubation at room temperature compared to that of the control. Hence, the essential oil of Melaleuca alternifolia can act as a green fungicide and is also a promising alternative to the synthetic chemical fungicide for controlling post-harvest disease on mangoes.

The antifungal mechanisms of plant volatile compound 1-octanol against Aspergillus flavus growth.

The exploitation of active ingredients from plant volatile organic compounds as natural gaseous fungicides shows remarkable potential for controlling fungal decay in postharvest agroproducts. Although 1-octanol is a common component of cereal volatiles, its antifungal potency against spoilage fungi in postharvest grains remains unclear. In this study, we studied the effectiveness of 1-octanol against Aspergillus flavus growth in postharvest grains and its mechanisms of action. 1-Octanol vapor and liquid contact dose-dependently inhibited A. flavus spore germination and mycelial growth at a low concentration. The simulated storage experiment demonstrated that 300 μL/L of 1-octanol vapor completely controlled A. flavus growth in wheat, corn, and paddy grains with 20% moisture content. 1-Octanol treatment irreversibly damaged the conidial and mycelial morphology of A. flavus and caused electrolyte leakage due to reduced plasma membrane integrity. It induced apoptosis along with morphological abnormalities, phosphatidylserine externalization, mitochondrial membrane potential depolarization, intracellular reactive oxygen species accumulation, and DNA fragmentation in A. flavus cells. Metabolomic analysis revealed that 1-octanol treatment disrupted the biosynthesis of unsaturated fatty acids, ATP-binding cassette transporters, amino acid metabolism, and glycerophospholipid metabolism. This study demonstrated the promising application potential of 1-octanol as a biofumigant for preventing fungal spoilage of postharvest cereal grains. KEY POINTS: • (1) 1-Octanol inhibits Aspergillus flavus growth in the vapor phase and liquid contact; • (2) 1-Octanol damages membrane integrity and induces apoptosis of A. flavus; • (3) Metabolomic changes in A. flavus mycelia were analyzed after 1-octanol treatment.

Impact of powdery mildew and sooty mold diseases on mango by natural fungicide

An investigation was carried out to determine the efficacy of some organic materials to manage powdery mildew and sooty mold diseases on mango, under natural field condition at Sharqia and Ismaelia governorates in Egypt. PlcoCure natural fungicide applied as foliar spray to find out its efficacy and profitability compared with control (no spray) and chemical fungicides Super sard potassium soap, Malathion, mineral oil to control sooty mold. All the treatments controlled the diseases significantly compared with control. As chemical, the PlcoCure showed significant impact on disease reduction. This natural fungicide gave a higher benefit with minimum production cost and this approach is proposed to the mango growing farmers to control the diseases. So, organic combination might be a better option to control powdery mildew and sooty mold diseases on mango rather than chemical control as it is cost-effective, environment friendly and good yield.