Botanical Fungicides Research Articles

Antifungal and toxicological evaluation of the alkaloids fraction from Neltuma nigra leaves

The use of synthetic fungicides for control soybean crop diseases has been cuestionated because of its impacts on human health and the environment. This work evaluated the composition, antifungal activity and toxicity of the alkaloids fraction obtained from Neltuma nigra leaves and compared its effect with the fungicide difenoconazole on Sclerotium rolfsii, Cercospora kikuchii, and C. sojina. Alkaloids fraction was extracted from leaves of N. nigra and its composition was analyzed by gas-chromatography coupled to mass spectrometry (GC-MS). The antifungal effect was recorded by measuring diameters of halos of inhibition of the growth of the different evaluated fungis. The toxicity of the alkaloids fraction was carried out using the method of Caenorhabditis elegans toxicity test. The extracted alkaloids fraction contained the alkaloids tryptamine (63.9%), tetrahydroxyharman (13.8%), phenethylamine (11.1%), cassine (10.4%), and N-formylphenylethylamine (0.8%). The alkaloids fraction was as effective against S. rolfsii as on the Cercospora strains, with minimum inhibitory doses of 25.0 μg disc-1 and inhibitory halos in the range of 8.5-13.0 mm, while difenoconazole had no effect on S. rolfsii. The toxicity of the alkaloid fraction (30.4-68.8 mg L-1) and difenoconazole (0.1-2.8 mg L-1) was tested on the reproduction, body length, and fertility of C. elegans. The fraction reduced the reproductive rate by 28.8-72.4% whereas difenoconazole did it from 12.2% to complete suppression. Neither of them affected the fertility of C. elegans. These findings suggest that the alkaloids fraction of N. nigra leaves is less toxic than difenoconazole and is a promising botanical fungicide against pathogenic soybean fungi.

Antifungal activity of Leonotis nepetifolia extracts against Colletotrichum species causing bean anthracnose and their phytochemical analysis using LC-MS

Bean anthracnose results in significant yield losses, and the present primary management strategy of using synthetic fungicides is hampered by a number of factors. This study assessed the antifungal effects of aqueous, methanolic, and ethyl acetate extracts of Leonotis nepetifolia (Lamiaceae) against Colletotrichum species that cause bean anthracnose. The poisoned food technique was used to evaluate extracts in-vitro, and trials were carried out on farmer's plots. On the other hand, phytochemical analysis was done using LC-MS. Results obtained in-vitro show that the ethyl acetate extract was the most effective since it completely inhibited mycelial development at concentrations of 5 mg/mL and 2.5 mg/mL. On the other hand, the aqueous and methanolic extracts exhibited a comparable inhibitory effect, and at the higher concentration (5.0 mg/mL), a remarkable percentage of inhibition of 73.3% and 83.1% was recorded. According to field trials, bean anthracnose incidence was low and there were fewer infected pods per plant in plots treated with L. nepetifolia extracts than in the negative control. In comparison to the negative control plots, extracts-treated plots had larger weights of 100 seeds but no discernible negative effect in seed germination. LC-MS analysis indicated the presence of Linoleoyl ethanolamide, Curcumol, Deguelin, 9,10-dihydroxy-12Z-octadecenoic acid, Naringenin-7-O-glucoside, and 9S-hydroxy-10e 12z 15z-octadecatrienoic acid in the ethyl acetate extract whereas 6-Methoxyluteolin, Genistein, 5,7,3,4-tetramethoxyisoflavone, and 3,4-Dihydroxymandelic acid were identified in the aqueous extract. Antifungal activity and the presence of bioactive components revealed by extracts in this study demonstrate the potential of L. nepetifolia as a source of botanical fungicide for the management of bean anthracnose.

Plant Extracts from the Yucatan Peninsula in the In Vitro Control of Curvularia lunata and Antifungal Effect of Mosannona depressa and Piper neesianum Extracts on Postharvest Fruits of Habanero Pepper.

Plant extracts are a valuable alternative for the control of phytopathogenic fungi in horticultural crops. In the present work, the in vitro antifungal effect of ethanol and aqueous extracts from different vegetative parts of 40 native plants of the Yucatan Peninsula on Curvularia lunata ITC26, a pathogen of habanero pepper (Capsicum chinense), and effects of the most active extracts on postharvest fruits were investigated. Among these, the ethanol extracts of Mosannona depressa (bark from stems and roots) and Piper neesianum (leaves) inhibited 100% of the mycelial growth of C. lunata. The three extracts were partitioned between acetonitrile and n-hexane. The acetonitrile fraction from M. depressa stem bark showed the lowest mean inhibitory concentration (IC50) of 188 µg/mL against C. lunata. The application of this extract and its active principle α-asarone in the postharvest fruits of C. chinense (500 µg/mL) was shown to inhibit 100% of the severity of the infection caused by C. lunata after 11 days of contact. Both samples caused the distortion and collapse of the conidia of the phytopathogen when observed using electron microscopy at 96 h. The spectrum of M. depressa enriched antifungal action is a potential candidate to be a botanical fungicide in the control of C. lunata in cultivating habanero pepper.

Chitosan-thymol nanoparticle with pH responsiveness as a potential intelligent botanical fungicide against Botrytis cinerea

The practical application of essential oils (EOs) as an alternative for synthetic pesticides in agricultural production is severely limited because of their instability, high volatility, and water insolubility. Nanoencapsulation of EOs is an important strategy to overcome these limitations. In view of this, this study aimed to develop chitosan-thymol nanoparticle (NCS-Thy) with pH-responsive which can be used as an intelligent botanical fungicide to control Botrytis cinerea. The NCS-Thy nanoparticle was prepared by ionic crosslinking method with the loading capacity and encapsulation efficiency of 29.87% and 41.92%, respectively. The synthesized NCS-Thy nanoparticle was further characterized by Fourier transform infrared spectroscopy analysis, transmission electron microscopy observation, and dynamic lights scattering. The results of release kinetics and antifungal activity of NCS-Thy under different pH conditions were determined. The results showed that the NCS-Thy nanoparticle had excellent pH-responsiveness and can release more thymol under acidic conditions formed by B. cinerea, thereby achieving higher antifungal effects. Therefore, compared with unencapsulated thymol, the NCS-Thy nanoparticle had higher antifungal activity against B. cinerea in vitro. In addition, both the protective and curative efficacies of detached leaf test and pot experiment were significantly higher than those of unencapsulated thymol. Among them, the protective efficacy of NCS-Thy in the pot experiment was 78.73%, which was significantly higher than that of unencapsulated thymol with 61.13%. Therefore, the pH-responsive chitosan-thymol nano-preparation had a promising prospect of application in practical management of gray mold as an intelligent botanical fungicide.

Bioefficacy of Lecanoric Acid Produced by Parmotrema austrosinense (Zahlbr.) Hale against Tea Fungal Pathogens

Lichens are symbiotic organisms that are composed of fungal partners and photosynthetic algal partners. During the symbiotic process in lichen thallus, the fungus synthesizes certain secondary metabolites in which lecanoric acid is very important in terms of antibiotic properties. Considering the vital importance of lecanoric acid, the present study aimed to produce lecanoric acid from the thallus of Parmotrema austrosinense lichen using Modified Bold’s basal salt medium and evaluate the bio-efficacy against tea fungal pathogens. Lecanoric acid was purified and confirmed by micro-crystallization method and subsequently bioassayed against tea fungal pathogens. The results revealed that lecanoric acid registered a significant antifungal activity in terms of the growth inhibition of test pathogens. Companion systemic and botanical fungicides were found to be inferior to lecanoric acid in the percentage of growth inhibition. The inhibition rate varied among tea pathogens. Of the tea pathogens tested, tea leaf disease-causing pathogens including Cercospora theae (C. theae), Glomerella cingulata (G. cingulate), and Phomopsis theae (P. theae) showed the highest percentage of growth inhibition followed by stem and root rot diseases. The present study suggests that lecanoric acid showed an inhibitory effect against tea pathogens, which might be due to antibiotic properties and fungicidal action of lecanoric acid.

Diagnosis and integrated management of onion wilt caused by Fusarium sp.

Onion wilt is an endemic disease in producing farms of Michoacán, Mexico that can reduce yields up to 25-30%. From onion plants with wilting symptoms, a monosporic isolate of the fungus Fusarium spp. was obtained, and its pathogenicity was verified. The fungus was morphologically and molecularly identified as Fusarium sp. Also, Fusarium sp. susceptibility to biological, botanical, and chemical pesticides was determined through four different bioassays. In experiment I, Trichoderma spp. in vitro antibiosis was tested using the cellophane technique. In Trials II and III, the in vitro effect of botanical and chemical fungicides on the pathogen was evaluated through the amended potato dextrose agar (PDA) culture technique. In Study IV, the biological efficacy of the products previously selected during in vitro assays was evaluated under greenhouse conditions. During the antibiosis trials, the commercial strain of Trichoderma virens (PHC Root Mate®) inhibited 33.3% of Fusarium sp. mycelial growth. Among botanical pesticides, cinnamon-neem extract (NeemAcar®) at doses of 0.06, 0.08- and 0.10-mL L-1 inhibited 100% mycelial growth of Fusarium sp. The fungicides benomyl, prochloraz, and pyraclostrobin completely suppressed Fusarium sp. development. Under greenhouse conditions, the incidence of wilt of plants treated with Trichoderma spp. and botanical extracts applied individually and in combination did not present significant differences from chemical fungicides treated. These results will help to develop an integrated disease management program for onion wilt.

The discovery of 3-fluoroalkyl indoles as potential antifungal agents to control tomato gray mold caused by Botrytis cinerea

Indole derivatives are a class of important heterocyclic natural products, which usually possess extensive bioactivities. In order to develop indole derivatives as potential fungicidal agents, a series of 3-perfluoroalkyl indole derivatives were prepared and investigated for their antifungal activities. The present data revealed that compound 3a was effective against eight test phytopathogenic fungi in vitro, and had the highest antifungal activity against B. cinerea, with an EC50 value of 0.94 µg/mL. Additionally, this indole exhibited excellent protective and curative efficacies against tomato gray mold in vivo. A possible mechanism of antifungal action for this compound was also explored. This study demonstrated that 3-perfluoroalkyl indole derivatives could potentially have utility as botanical fungicides for the management of phytopathogenic fungi.

Antifungal alkaloids from Mahoniafortunei against pathogens of postharvest fruit

Postharvest pathogens can affect a wide range of fresh fruit and vegetables, including grapes, resulting in significant profit loss. Isoquinoline alkaloids of Mahoniafortunei, a Chinese herbal medicine, have been used to treat infectious microbes, which might be effective against postharvest pathogens. The phytochemical and bioactive investigation of this plant led to the isolation of 18 alkaloids, of which 9 compounds inhibited the growth of Botrytiscinerea and 4 compounds against Penicilliumitalicum. The antifungal alkaloids could change the mycelium morphology, the total lipid content, and leak the cell contents of B.cinerea. Furthermore, the two most potent antifungal alkaloids, berberine (13) completely inhibited effect on gray mold of table grape at 512 mg L−1, while jatrorrhizine (18) exhibited an inhibition rate > 90% on grape rot at the same concentration, with lower cytotoxicity and residue than chlorothalonil, which suggested that ingredients of M.fortunei might be a low-toxicity, low-residue, eco-friendly botanical fungicide against postharvest pathogens.Graphical

Mechanism of Antifungal Activity of Piperine against Botrytis cinerea

P iperine is a major component of plants of the Piperaceae family which is widely used in medical science. Botrytis cinerea is one of the most important phytopathogenic fungi causes postharvest losses in fruits and vegetables. To verify the possibility of using piperine as a botanical fungicide against B. cinerea, we determined the in vivo and in vitro antifungal activity of piperine against B. cinerea and investigated its antifungal mechanism effects on the mycelial surface, membrane integrity, soluble protein content, superoxide dismutase, catalase, succinate dehydrogenase and the malondialdehyde content of B. cinerea. The in vitro antifungal activity assay indicated that the EC50 value of piperine against B. cinerea was 58.66 μg/mL and the in vivo antifungal assay showed that piperine at 400 μg/mL suppressed 93.88% growth of B. cinerea on Lycopersic esculentum. The antifungal mechanism assay showed that piperine could inhibit mycelial growth of B. cinerea by reducing antioxidant activity, inhibiting the tricarboxylic acid pathway, and lysing the cell membrane. All these results indicated that piperine as a natural component has the potential to control B. cinerea and can be considered as a botanical fungicide for postharvest disease control of gray mold.

Antifungal alkaloids from the branch-leaves of Clausena lansium Lour. Skeels (Rutaceae).

The rational utilization of botanical secondary metabolites is one of the strategies to reduce the application of chemical fungicides. The extensive biological activities of Clausena lansium indicate that it has the potential to develop botanical fungicides. A systematic investigation on the antifungal alkaloids from C. lansium branch-leaves following the bioassay-guided isolation was implemented. Sixteen alkaloids, including two new and nine known carbazole alkaloids, one known quinoline alkaloid and four known amides, were isolated. Compounds 4, 7, 12 and 14 showed strong antifungal activity on P. capsici with EC50 values ranging from 50.67 to 70.82μg/mL. Compounds 1, 3, 8, 10, 11, 12 and 16 displayed different degrees of antifungal activity against B. dothidea with EC50 values ranging from 54.18 to 129.83μg/mL. It was reported for the first time that these alkaloids had antifungal effects on P. capsici or B. dothidea, and their structure-activity relationships were further discussed systematically. Additionally, among all alkaloids, dictamine (12) had the strongest antifungal activities against P. capsici (EC50 = 50.67μg/mL) and B. dothidea (EC50 = 54.18μg/mL), and its physiological effects on P. capsici and B. dothidea were also further evaluated. C. lansium was a potential source of antifungal alkaloids, and C. lansium alkaloids had the potential as lead compounds of botanical fungicides in the development of new fungicides with novel action mechanism. This article is protected by copyright. All rights reserved.

Activity of the botanical compound thymol against kiwifruit rot caused by Fusarium tricinctum and the underlying mechanisms.

Kiwifruit rot is an important disease caused by different fungal pathogens, which can lead to huge economic loss in the kiwifruit industry. The aims of this study were to discover an effective botanical compound that significantly inhibits the pathogens causing kiwifruit rot, evaluate its control efficacy against this disease, and reveal the underlying mechanisms. A strain of Fusarium tricinctum (GF-1), isolated from diseased kiwifruit, could cause fruit rot in both Actinidia chinensis var. chinensis and Actinidia chinensis var. deliciosa. Different botanical chemicals were used for antifungal activity test against GF-1 and thymol was the most effective one with a 50% effective concentration (EC50 ) of 30.98 mg L-1 . The minimal inhibitory concentration (MIC) of thymol against GF-1 was 90 mg L-1 . Control efficacy of thymol against kiwifruit rot was evaluated and the results indicated that thymol could effectively decrease the occurrence and spread of kiwifruit rot. The mechanisms underlying the antifungal activity of thymol against F. tricinctum were investigated, and it showed that thymol could significantly damage the ultrastructure, destroy the plasma membrane integrity, and instantaneously increase energy metabolisms of F. tricinctum. Further investigations indicated that thymol could extend shelf life of kiwifruit by increasing their storability. Thymol can effectively inhibit F. tricinctum that is one of the causal agents of kiwifruit rot. Multiple modes of action are involved in the antifungal activity. The results of this study indicate that thymol can be a promising botanical fungicide to control kiwifruit rot and provide useful references for thymol application in agriculture system. © 2023 Society of Chemical Industry.

Novel Design of Citral-Thiourea Derivatives for Enhancing Antifungal Potential against Colletotrichum gloeosporioides.

Although much progress has been made in developing botanical fungicides to combat fungal diseases in crops, there remains a great need to improve the efficiency and long-term safety of these fungicides. This study proposes a novel strategy for designing citral-thiourea derivatives that feature such desirable properties. The motivation of the work herein was to enhance the antifungal activity of citral against C. gloeosprioides by exploiting the synergistic effect that arises from combining citral and thiourea compounds, thereby producing citral-thiourea derivatives that exhibit good long-term safety. The results revealed that the generated compounds e1, e3, e6, e18, and g showed remarkable antifungal activities against C. gloeosprioides, with corresponding EC50 values reaching 0.16, 1.66, 1.37, 4.76, and 4.60 mg/L, respectively, showing that the compounds significantly outperformed both the positive control kresoxim-methyl and the commercially available fungicide carbendazim. Furthermore, compound g showed stronger protective efficacy against C. gloeosprioides than carbendazim on mango fruit at 25 mg/L. Investigating the preliminary structure-activity relationship (SAR) of the compounds also revealed that the citral-thiourea derivatives exhibited higher antifungal activities against C. gloeosprioides compared to citral and thiourea compounds. This reinforcement of antifungal activity observed in the derivatives was found to be attributable to the two characteristics of low molecular size and the presence of a fluorine atom in the meta-position of the benzene ring. Beyond this, it was determined from QSAR that two molecular descriptors (the Kier-Hall index (order 3) and Tot dipole of the molecules) were negatively related to the antifungal activity of the citral-thiourea derivatives, while one other (the maximum resonance energy of a C-H bond) was positively related to their antifungal activity. More importantly, the citral-thiourea derivatives with high antifungal activities (i.e., compounds e1, e3, e6, e14, e15, e18, and g) exhibited negligible cytotoxicity to LO2 and HEK293T cell lines. The antifungal mechanism of the generated citral-thiourea derivatives was investigated by scanning electron microscopy (SEM) and relative conductivity. The derivatives were found to affect mycelial morphology and increase fungal cell membrane permeability, thereby resulting in the destruction of fungal cell membranes. These promising results provide novel insights into the study and potential application value of citral-thiourea derivatives as high-efficiency antifungal agents against C. gloeosprioides.

Breeding of Highly Virulent Beauveria bassiana Strains for Biological Control of the Leaf-Eating Pests of Dalbergia odorifera

Dalbergia odorifera (D. odorifera), commonly named the fragrant rosewood, is one of the second-level protected wild plants in China, and one of 34 species of rosewood in five genera and eight categories in the National Standard of China. As a kind of traditional Chinese medicine (TCM), it plays an important role in the pharmaceutical industry, including the treatment of cardiovascular diseases, rheumatic pain, etc. With the continuous expansion of the planting area of D. odorifera, the diseases and pests of D. odorifera become more and more serious, among which leaf-eating pests are the most serious. In this study, ultraviolet rays and microwaves were used to mutagenize Beauveria bassiana (B. bassiana) strain HNCMBJ-P-01, and excellent mutant strains with high spore yield and high virulence were screened out, and then they were prepared into a wettable powder for forest control experiments to study their biocontrol effects. The virulence screening test showed that the virulence of strain HBWB-44 was the strongest, and the 10 day corrected mortality rate was 80.00%, and the lethal time was 5.622 days. The results of biological control test showed that the control effect of B. bassiana wettable powder 100 times solution reached 60.89%, second only to the botanical fungicide matrine. Generically, The B. bassiana that we screened and mutated showed a good killing effect on Plecoptera bilinealis (P. bilinealis), and the wettable powder produced by it showed a good control effect on the leaf-eating pests of D. odorifera. The application of fungal insecticides in plantations has a good prospect for controlling the occurrence of leaf-eating pests of D. odorifera.

Antifungal activity of potato glycoalkaloids and its potential to control severity of dry rot caused by Fusarium sulphureum

AbstractIdentifying novel sources of antifungal agents from common food waste (i.e., green potato peel) could provide an inexpensive alternative for botanical fungicides. Identification of the potato (Solanum tuberosum L.) glycoalkaloids (PGAs) content in the green peel by high performance liquid chromatography (HPLC), and the antifungal activity of PGAs against the potato dry rot pathogen Fusarium sulphureum were evaluated using addition of PGAs to the medium in vitro and injection of it into potato tubers in vivo. The results of HPLC showed that the average content of PGAs per kilogram green potato peel was 2238.76 mg, and the α‐chaconine content was about 1.8 times higher than that of α‐solanine. Antifungal activity test of PGAs in vitro uncovered that mycelium growth rate of F. sulphureum was inhibited in potato dextrose agar (PDA) medium with varying concentrations of PGAs, and the inhibition rate was positively correlated with PGAs concentration. Moreover, PGAs were also capable of reducing the contents of malondialdehyde, total phenols, flavonoids as well as the activities of peroxidase and superoxide dismutase induced by F. sulphureum through inhibiting or killing part of mycelium. These findings suggest that the protective effect of PGAs against potato dry rot might be associated with the direct fungistatic effect on the pathogen. Thus, PGAs can serve as a promising botanical fungicide to substitute, at least partially, the use of synthetic fungicides in the disease management of potato.

Efficacy of Botanical Mixture and Fungicides to Combat Sigatoka Disease in Banana Cultivation

Black Sigatoka disease caused by Mycosphaerella fijiensis seriously threatens banana cultivation worldwide. This infirmity is controlled by the recurrent application of synthetic fungicides, which leads to several adverse effects. Plant extracts with antifungal potential have long been investigated as they contain secondary bioactive compounds for protecting crops from microbial infection. This study compared the antifungal activities of both botanical mixtures and recommended fungicides to control Black Sigatoka in banana. Laboratory and field studies were conducted to assess the antifungal activity of the botanical mix prepared from eight different herbal plant parts against M. fijiensis, with two recommended fungicides as the positive control. In vitro results showed that the radial growth of the fungus was significantly impaired (P<0.05.) by the addition of the botanical mixture, fungicides, and combination of the botanical mixture (BM) and fungicides in the PDA media. Mycosphaerella fijiensis differed in their reaction to the BM and fungicides, and combination of BM and fungicides, but on the whole, growth inhibition increased with the concentration. In field experiments, all the treatments reduced the disease incidence significantly compared to the unsprayed control, where the disease severity index (DSI) increased from 43.88 to 67.77 within 28 days. After the first spray, the botanical mixture and fungicides (Chlorothalonil and Carbendazim) reduced the disease severity index to 39.7, 41.19, and 44.44, respectively. Fungicides and combinations of Chlorothalonil + BM and Carbendazim + BM showed the lowest DSI, 34.07 and 35.83, respectively. The results show that combining the synthetic and botanical mixture is more effective for controlling the disease. The study reveals the possibility of utilizing a botanical mixture as an integrated approach to manage Black Sigatoka disease more efficiently and in an eco-friendly manner.

An Extensive Review of Strawberry (Fragaria×ananassa) Diseases and Integrated Management Approaches: Current Understanding and Future Directions

Strawberry production has increased by more than double in the past two decades. Meanwhile, it is also susceptible to various diseases which have become a limiting factor in its yield increment. Indiscriminate use of chemicals in the management of diseases has brought several adverse effects to the environment and human health. Thus, this review aims to present the different diseases of strawberries including their epidemiology, disease cycle, and symptoms. Moreover, the focus has been given to Integrated Management. More than ten dozen of literature including journal articles, books, websites, and organizational reports were thoroughly reviewed to get the related information. Botrytis grey mold rot, anthracnose, strawberry leaf spot, powdery mildew, and red stele are the major fungal diseases whereas angular leaf spot is the serious bacterial disease of strawberries. It is severely infected by viruses such as strawberry mottle virus and crinkling and vein banding virus. In addition to this nematode causes ring spots, root-knot, and root lesions on strawberries. Integrated disease management approaches should be adopted for effective and sustainable management. It may include cultural methods, physical methods, use of bio-control agents, botanical fungicides, and at last chemicals if the disease is severe.

Stability analysis and optimal control for leaf brown spot disease of rice

<abstract> <p>Leaf brown spot, caused by fungi, is a terrible plant disease, and it can significantly reduce the quality and quantity of rice. In this paper, we developed the model based on leaf brown spot disease development and considered a preventive treatment using botanical fungicide. In addition, we develop a model with suitable optimal control strategies. The result shows disease-free equilibrium is asymptotically stable when $R_0>1$. In contrast, the endemic equilibrium is asymptotically stable when $R_0 > 1$. The obtained optimal control to can reduce the number of infected plants compared to that without control. In addition, the analytical results were confirmed by numerical simulations of the occurrence of the theoretical results.</p> </abstract>

Identification of Enolase 1 as a Potential Target for Magnaporthe oryzae: Integrated Proteomic and Molecular Dynamics Simulation

Rice blast is an essential factor affecting rice yield and quality, which is caused by Magnaporthe oryzae (M. oryzae). Isobavachalcone (IBC) is a botanical fungicide derived from the seed extract of the Leguminosae plant Psoralea corylifolia L. and has shown an excellent rice blast control effect in field applications. To explore the potential targets of rice blast control, the analysis of the differentially expressed proteins (DEPs) between the liquid culture medium of mycelium treated by 10 mg/L of IBC for 2 h and the control group indicated that Enolase 1 (ENO1) was the most significantly down-regulated DEP with a fold change value of 0.305. In vitro experiments showed that after treating liquid culture mycelium with 10 mg/L of IBC for 0.5, 1, 2, 4, and 8 h, the enzymatic activity of ENO1 in the IBC experimental groups was 0.97, 0.75, 0.52, 0.44, and 0.39 times as much as in the control groups, respectively. To further explore the molecular interaction and binding mode between IBC and ENO1, the three-dimensional structure of ENO1 was established based on homology modeling. Molecular docking and molecular dynamics simulation showed that IBC had a pi-pi stacking effect with the residue TYR_365, a hydrogen bond interaction with the residue ARG_393, and hydrophobic interactions with non-polar residues ALA_361, LYS_362, and VAL_371 of ENO1. These findings indicated that ENO1 is a potential target of M. oryzae, which would pave the way for screening novel effective fungicides targeting ENO1.

Polymethoxylated flavonoids (PMFs)-loaded citral nanoemulsion controls green mold in citrus by damaging the cell membrane of Penicillium digitatum

Citrus is susceptible to Penicillium digitatum (P. digitatum) infection in post-harvest storage, resulting in enormous economic losses. This study aimed to investigate the antifungal activity and potential mechanism of the combination of Polymethoxylated flavones (PMFs) and citral (two natural antifungal components derived from citrus) against P. digitatum in vitro and citrus fruit. The results show that PMFs can enhance the antifungal activity of citral nanoemulsion, and PMFs-loaded citral nanoemulsion (PCT) has significant antifungal activity in a concentration-dependent manner. PCT can evidently inhibit spore germination and mycelial growth in vitro, and effectively control the growth of green mold on postharvest citrus fruit. Furthermore, PCT treatment resulted in the alteration of mycelia morphology, accumulation of reactive oxygen species, and membrane lipid peroxidation. These changes can disrupt the normal structure and function of the cell membrane, as evidenced by the reduction of total lipid and ergosterol content in the mycelia and the stronger red fluorescence of the cells emitted after PI staining. Based on the above results, we infer that PCT has a strong inhibitory effect on P. digitatum, and its potential mechanism is related to the destruction of the cell membrane. Therefore, PCT can be considered as a botanical fungicide for citrus preservation.

Effectiveness of several plant extracts as botanical fungicides to control damping-off disease caused by Sclerotium rolfsii on soybean

Sclerotium rolfsii is the causal organism of the damping-off disease of soybean. Control of this disease is usually carried out by using chemical fungicides that have a negative impact on the environment. One of the efforts to overcome this problem is by using botanical fungicides from plant extracts. This study aims to determine the effect of plant extracts from Alpinia purpurata, Zingiber officinale, Curcuma longa, Curcuma xanthorrhiza, and Kaempferi galanga on the in-vitro growth of Sclerotium rolfsii and on the in-vivo of damping-off disease of soybean. In addition, a phytochemical test was also undertaken to determine the content of secondary compounds found in plant extracts. The experiment was carried out at the Chemistry Laboratory of the Faculty of Mathematics and Natural Sciences, Microbiology Laboratory and a Greenhouse of Faculty of Agriculture at the University of Mataram, from July until October 2020. The experiments used a completely randomized design (CRD) with seven treatments and three replications. The seven treatments were A. purpurata, Z. officinale, C. longa, C. xanthorrhiza, and K. galanga with a concentration of 5% (v/v), control (+), and the alcohol (-). The results showed that the extracts of A. purpurata, Z. officinale, C. longa, C. xanthorrhiza, and K. galanga with a concentration of 5% could suppress the growth of S.rolfsii by in-vitro. However, in the in-vivo trial, no extracts could suppress damping-off disease of soybean.