Germ Tube Elongation Research Articles

Enhancing biocontrol efficacy of Cryptococcus laurentii induced by carboxymethyl cellulose: Metabolic pathways and enzyme activities insights

The synergistic biocontrol effects of Cryptococcus laurentii cultured with carboxymethyl cellulose (CMC) were studied to control Penicillium italicum in postharvest grapefruit. The results showed that C. laurentii was cultured in 0.5 % (w/v) CMC (CMC-C. laurentii) significantly inhibited elongation of germ tubes, decreased germination of conidia in P. italicum, and reduced disease in grapefruit. Besides, CMC significantly increased ATP synthase and population proliferation of C. laurentii. Moreover, metabolomics analysis revealed 24 significantly differentially metabolites in CMC-C. laurentii including the citrate cycle, metabolism of glyoxylic acid, dicarboxylic acid, phenylalanine, tyrosine, and tryptophan and amino acid biosynthesis. These results demonstrate that CMC could significantly enhance the ATP synthase by promoting the citrate cycle, providing energy for strain growth, and thereby increasing the biocontrol effectiveness of C. laurentii. Furthermore, adding CMC enhanced the activities of strain extracellular hydrolases and antioxidases, which increased the resistance to stress, thus improving the antagonistic effect of C. laurentii.

Cestrum tomentosum L.f. Extracts against Colletotrichum scovillei by Altering Cell Membrane Permeability and Inducing ROS Accumulation.

Chili pepper anthracnose, caused by Colletotrichum spp., is a significant biotic stress affecting chili fruits globally. While fungicide application is commonly used for disease management due to its efficiency and costeffectiveness, excessive use poses risks to human health and the environment. Botanical fungicides offer advantages such as rapid degradation and low toxicity to mammals, making them increasingly popular for sustainable plant disease control. This study investigated the antifungal properties of Cestrum tomentosum L.f. crude extracts (CTCE) against Colletotrichum scovillei. The results demonstrated that CTCE effectively inhibited conidia germination and germ tube elongation at 40 µg/ml concentrations. Moreover, CTCE exhibited strong antifungal activity against C. scovillei mycelial growth, with an EC50 value of 18.81 µg/ml. In vivo experiments confirmed the protective and curative effects of CTCE on chili pepper fruits infected with C. scovillei. XTT analysis showed that the CTCE could significantly inhibit the cell viability of C. scovillei. Mechanistic studies revealed that CTCE disrupted the plasma membrane integrity of C. scovillei and induced the accumulation of reactive oxygen species in hyphal cells. These findings highlight CTCE as a promising eco-friendly botanical fungicide for managing C. scovillei infections in chili peppers.

Biocontrol efficacy of Botrytis cinerea on postharvest tomato fruit by the endophytic bacterium Bacillus velezensis BE1

Endophytic bacteria offer numerous advantages in the control of postharvest diseases. Bacillus velezensis has been identified as a promising biocontrol agent against postharvest pathogens in various fruits and vegetables. In this study, B. velezensis BE1 was identified by 16S rRNA sequencing and caused 76.9 % inhibition against Botrytis cinerea in dual culture assay. The cell-free culture filtrate (CFCF) of B. velezensis strongly inhibited the growth, spore germination, and germ tube elongation of B. cinerea. Moreover, 11 bioactive compounds were identified in the CFCF using gas chromatography-mass spectrometry, and phthalic acid, dioctyl ester was the predominant component by 72.92 %. Scanning and transmission electron microscopy observations revealed that the CFCF causes irreversible morphological and ultrastructural damage to the fungal hyphae and conidia, including deformed, wrinkled, lysis, collapse, and degradation of cytoplasmic organelles. The incidence and severity of gray mold were significantly suppressed after applying CFCF at 50 % in tomato fruit. The application of CFCF caused an increase in the total phenolics and flavonoids content in tomato fruit compared with the control throughout the experiment. Furthermore, the activities of enzymes associated with defense such as phenylalanine ammonia-lyase, polyphenoloxidase, and peroxidase were significantly higher in the treated tomatoes relative to the untreated group. These results indicate that B. velezensis BE1 has significant potential as an effective biocontrol agent against the pathogen B. cinerea, offering a valuable approach for controlling gray mold in postharvest fruit.

Control of Botrytis cinerea from Chilean grapevines by pydiflumetofen: baseline and carboxamide-mutant sensitivity.

The gray mold (Botrytis cinerea; Botrytis) is the main disease affecting grapevines production in Chile. Succinate Dehydrogenase Inhibitors (SDHI) belonging to the carboxamides fungicide family are a key tool for the control of Botrytis in grapevines from Chilean Central Valley. This study aimed to determine the sensitivity of Chilean Botrytis population to the new generation carboxamide pydiflumetofen. Conidial germination (CG) and germ-tube elongation (GTE) sensitivity assays were conducted on 200 single-spore isolates collected during the 2016-2017 season. The mean effective concentration that inhibited 50% (EC50) of CG in the Botrytis population was 0.0545 µg/mL, with mean values of 0.066 µg/mL and 0.042 µg/mL, for table and wine grapes, respectively. The mean EC50 value of GTE was 0.000245 µg/mL, 0.0003 µg/mL, and 0.0019 µg/mL for the total, table grape, and wine grape populations, respectively. The comparison between pydiflumetofen and fludioxonil, a highly-efficient fungicide carrying a different mode of action, showed the 87.5% and 97.5% of Botrytis control with an EC50 threshold of 0.1 µg/mL, in table grape, and wine grape populations, respectively. No cross-resistance between pydiflumetofen and fludioxonil was detected. For nine isolates with reduced pydiflumetofen sensitivity, we evaluated SdhB mutations using a qPCR-HRM diagnostic system. Two isolates carried the sdhBP225/H272R genotype and two the sdhBP225/H272Y. Additional analysis of SdhB mutant isolates determined that pydiflumetofen controls wild-type as well as sdhBP225/H272R and sdhBP225H/H272 mutants. Pydiflumetofen does not control CG in the sdhBP225/H272Y mutant but is effective in the GTE control. Pydiflumetofen significantly controls Botrytis independently of the SdhB genotype in wounded berry assays. This condition resembles the berry cracking due to heavy rainfall right before harvest, as seen in recent years in the Chilean Central Valley. The findings demonstrate that pydiflumetofen effectively controls the grapevine Botrytis population, suggest a moderate risk of pydiflumetofen resistance, and highlight the significance of incorporating genetic data into the design of control programs.

Metconazole inhibits fungal growth and toxin production in major Fusarium species that cause rice panicle blight

Rice panicle blight (RPB) caused by various Fusarium spp. is an emerging disease in the major rice-growing regions of China. Epidemics of this disease cause significant yield loss and reduce grain quality by contaminating panicles with different Fusarium toxins. However, there is currently no registered fungicide for the control of RPB in China. The 14α-demethylation inhibitor (DMI) fungicide metconazole has been shown to be effective against several Fusarium spp. that cause wheat head blight, wheat crown rot and maize ear rot. In this study, we investigated the specific activity of metconazole against six Fusarium spp. that cause RPB. Metconazole significantly inhibited mycelial growth, conidium formation, germination, germ tube elongation and major toxin production in Fusarium strains collected from major rice-growing regions in China, as well as disrupting cell membrane function by inhibiting ergosterol biosynthesis. Greenhouse experiments indicated a significant reduction in blight occurrence and toxin accumulation in rice panicles treated with metconazole. Overall, our study demonstrated the potential of metconazole for managing RPB and toxin contamination, as well as providing insight into its bioactivities and modes of action of metconazole against distinct Fusarium spp.

Fungicide-Loaded Liposomes for the Treatment of Fungal Diseases in Agriculture: An Assessment of Botrytis cinerea.

In this work, liposomes loaded with the fungicide, Fludioxonil (FLUD), for the containment of fungal diseases in agriculture were developed. Three types of vesicles with different compositions were compared: (I) plain vesicles, composed of soy phosphatidylcholine and cholesterol; (II) PEG-coated vesicles, with an additional polyethylene glycol coating; and (III) cationic vesicles, containing didodecyldimethylammonium bromide. Nanometric-sized vesicles were obtained both by the micelle-to-vesicle transition method and by the extrusion technique, and encapsulation efficiency, drug loading content, and Zeta potential were determined for all the samples. The extruded and PEGylated liposomes were the most stable over time and together with the cationic ones showed a significant prolonged FLUD release capacity. The liposomes' biological activity was evaluated on conidial germination, germ tube elongation and colony radial growth of the ascomycete Botrytis cinerea, a phytopathogenic fungus affecting worldwide many important agricultural crops in the field as well as in the postharvest phase. The extruded and PEGylated liposomes showed greater effectiveness in inhibiting germ tube elongation and colony radial growth of the fungal pathogen, even at 0.01 µg·mL-1, the lowest concentration assessed.

Chitosan stabilized lemon essential oil nanoemulsion controls black mold rot and maintains quality of table grapes

Aspergillus carbonarius infection leads to black mold rot in table grapes, causes grape decay, reduces fruit quality and marketability, which produces significant economic losses. This study investigated the antifungal efficacy of chitosan-stabilized lemon essential oil nanoemulsion (LO-CNE) against A. carbonarius and black mold rot of table grapes. LO-CNE was prepared with a mean diameter of 130.01 ± 8.34 nm. LO-CNE exhibited superior antifungal activity, reduced spore germination and germ tube elongation, decreased the antioxidant enzyme activities in A. carbonarius; the minimal inhibitory concentration of LO-CNE was determined to be 30 mg/mL. LO-CNE reduced the occurrence of black mold rot by 63 % and lesion diameter by 56.78 % in table grapes compared to the control. At their peak activity level, the grapes treated with LO-CNE exhibited significantly enhanced antioxidant and defense-related enzyme activities. Specifically, polyphenol oxidase activity increased by 2.27-fold, peroxidase activity by 2.22-fold, superoxide dismutase activity by 0.68-fold, catalase activity by 1.61-fold, phenylalanine ammonia-lyase activity by 3.38-fold, and ascorbate peroxidase activity by 2.36-fold. The LO-CNE application reduced natural decay by 95 %, weight loss by 15 % compared to the control, and effectively maintained the quality parameters of table grapes. Therefore, LO-CNE can be considered an alternative disease-control agent for grape preservation.

Suppression of anthracnose disease by orsellinaldehyde isolated from the mushroom Coprinus comatus.

Anthracnose caused by Colletotrichum species is one of the most devastating diseases of fruits and crops. We isolated and identified an antifungal compound from the mushroom Coprinus comatus and investigated its inhibitory potential against anthracnose disease-causing fungi with the goal of discovering natural products that can suppress anthracnose-caused plant disease. The culture filtrate of C. comatus was subjected to a bioassay-guided isolation of antifungal compounds. The active compound was identified as orsellinaldehyde (2,4-dihydroxy-6-methylbenzaldehyde) based on mass spectroscopy and nuclear magnetic resonance analyses. Orsellinaldehyde displayed broad-spectrum inhibitory activity against different plant pathogenic fungi. Among the tested Colletotrichum species, it exhibited the lowest IC50 values on conidial germination and germ tube elongation of Colletotrichum orbiculare. The compound also showed remarkable inhibitory activity against Colletotrichum gloeosporiodes. The staining of Colletotrichum conidia with fluorescein diacetate and propidium iodide demonstrated that the compound is fungicidal. The postharvest in-vivo detached fruit assay indicated that orsellinaldehyde suppressed anthracnose lesion symptoms on mango and cucumber fruits caused by C. gloeosporioides and C. orbiculare, respectively. Orsellinaldehyde was identified as a potent antifungal compound from the culture filtrate of C. comatus. The inhibitory and fungicidal activities of orsellinaldehyde against different Colletotrichum species indicate its potential as a fungicide for protecting various fruits against anthracnose disease-causing fungi.

Inhibitory Activities of Five Fungicides on Alternaria suffruticosae and Their Field Control Efficacy Against Tree Peony Black Spot.

Tree peony black spot (TPBS), mainly caused by Alternaria suffruticosae, is a common leaf disease on the ornamental peony, which poses a great threat to the flower buds in the current year and the flowering quality in the next year. However, there is only one fungicide registered for the control of this disease, difenoconazole. In order to avoid the severe problem of pathogen resistance caused by long-term use of difenoconazole, it is necessary to screen more chemical fungicides for the prevention and control of TPBS. In this study, the biological activities of flutolanil, phenamacril, pyraclostrobin, and boscalid on mycelial growth, conidial germination, germ tube elongation, and sporulation quantity of A. suffruticosae were determined, and the field control efficacy was tested to evaluate the preventive and therapeutic activities. Difenoconazole was used as a control simultaneously. The results showed that pyraclostrobin had the strongest inhibitory effects on the conidial germination, mycelium growth, germ tube elongation, and sporulation quantity, with the average EC50 values of 0.0517, 0.5343, 0.0008, and 0.8068 μg/ml, respectively. The inhibitory activity of flutolanil on the four developmental stages of A. suffruticosae was weaker than that of the other three fungicides. Compared with flutolanil, boscalid, the other succinate dehydrogenase inhibitor, had more strong inhibitory effects on the mycelial growth and sporulation quantity, with the average EC50 values of 3.8603 and 1.4760 μg/ml, respectively. Phenamacril had a moderate inhibitory level and had more inhibitory activity on conidial germination and germ tube elongation, with the average EC50 values of 31.5349 and 5.2597 μg/ml, respectively. All of the four fungicides had no significant effects on the shape of spores and germ tubes. The control fungicide difenoconazole had the strongest inhibitory activity on mycelial growth, and the average EC50 value was only 0.3297 μg/ml. However, its inhibitory activity on the other three growth stages was not high. In the field trials, pyraclostrobin had high control efficacy on TPBS even at low concentrations, reaching a minimum of 62.6293%, which was higher than that of difenoconazole. The other three fungicides had higher control efficacy at high concentrations but decreased significantly at low concentrations. Considering the dosage and control efficacy, pyraclostrobin was the first choice for the control of TPBS. Pyraclostrobin is the preferred alternative fungicide to difenoconazole for the prevention and control of TPBS in production.

Inhibitory Properties of Cinnamon Bark Oil against Postharvest Pathogen Penicillium digitatum In Vitro.

Penicillium digitatum is a major postharvest pathogen that threatens the global citrus fruit industry and causes great economic losses annually. In the present study, inhibitory properties of cinnamon bark oil (CBO) against P. digitatum in vitro were investigated. Results indicated that 0.03% CBO could efficiently inhibit the spore germination, germ tube elongation, mycelial growth, colonial expansion and conidial accumulation of P. digitatum. The results of fluorescein diacetate (FDA) and MitoTraker Orange (MTO) staining also proved the suppression effects of CBO against P. digitatum. Meanwhile, CBO could inhibit green mold rots induced by P. digitatum in citrus fruit when the working concentration of CBO exceeded 0.06%. In addition, the expressions of 12 genes critical for the growth and virulence of P. digitatum were also significantly regulated under CBO stress. Through a transcriptomic analysis, a total of 1802 common differentially expressed genes (DEGs) were detected in P. digitatum after 4 h and 8 h of CBO treatment. Most of the DEG products were associated with carbohydrate, amino acid and lipid metabolism. They directly or indirectly led to the disturbance of the membrane and the generation of reactive oxygen species (ROS). Our results may deepen the understanding of antifungal properties of CBO against P. digitatum and provide the theoretical foundation to uncover the antifungal mechanism of CBO at the molecular level.

In Vitro and Ex Vivo Antifungal Activities of Metconazole against the Rice Blast Fungus Pyricularia oryzae.

Rice blast, caused by the filamentous fungus Pyricularia oryzae, has long been one of the major threats to almost all rice-growing areas worldwide. Metconazole, 5-(4-chlorobenzyl)-2, 2-dimethyl-1-(1H-1, 2, 4-triazol-1-ylmethyl) cyclopentanol, is a lipophilic, highly active triazole fungicide that has been applied in the control of various fungal pathogens of crops (cereals, barley, wheat), such as the Fusarium and Alternaria species. However, the antifungal activity of metconazole against P. oryzae is unknown. In this study, metconazole exhibited broad spectrum antifungal activities against seven P. oryzae strains collected from rice paddy fields and the wild type strain P131. Scanning electron microscopic analysis and fluorescein diacetate staining assays revealed that metconazole treatment damaged the cell wall integrity, cell membrane permeability and even cell viability of P. oryzae, resulting in deformed and shrunken hyphae. The supplementation of metconazole in vitro increased fungal sensitivity to different stresses, such as sodium dodecyl sulfate, congo red, sodium chloride, sorbitol and oxidative stress (H2O2). Metconazole could inhibit key virulence processes of P. oryzae, including conidial germination, germ tube elongation and appressorium formation. Furthermore, this chemical prevented P. oryzae from infecting barley epidermal cells by disturbing appressorium penetration and subsequent invasive hyphae development. Pathogenicity assays indicated a reduction of over 75% in the length of blast lesions in both barley and rice leaves when 10 μg/mL of metconazole was applied. This study provides evidence to understand the antifungal effects of metconazole against P. oryzae and demonstrates its potential in rice blast management.

Effects of TrPLDs on the pathogenicity of Trichothecium roseum infected apple fruit

Phospholipase D plays a critical regulatory role in the pathogenicity of filamentous fungi. However, the molecular mechanism of PLD regulating the pathogenicity of filamentous fungi has not been reported. In this research, the previously constructed TrPLD1 and TrPLD2 (TrPLDs) mutants were used as test strains. Firstly, the function of TrPLDs in Trichothecium roseum was studied. Then, the effects of TrPLDs on the pathogenicity of T. roseum and the quality of the inoculated apples were verified. The results suggested that the deletion of TrPLD1 delayed the spore germination of ΔTrPLD1 and inhibited germ tube elongation by down-regulating the expressions of TrbrlA, TrabaA and TrwetA. By down-regulating the extracellular enzyme-coding gene expressions, ΔTrPLD1 inhibited the degradation of apple fruit cell wall and the change of fatty acid content during infection, reduced the cell membrane permeability and malondialdehyde (MDA) content of apple fruit, thereby maintaining the integrity of fruit cell membrane, and reduced the pathogenicity of ΔTrPLD1 to apple and kept the quality of apple. However, ΔTrPLD2 did not have a significant effect on the infection process of apple fruit by the pathogen.

Inhibitory Effect of L-Methionine on Alternaria alternata Based on Metabolomics Analysis.

Alternaria alternata is the main pathogenic fungus of postharvest black spots in fruits and vegetables. This study aimed to explore the antifungal activity of methionine on A. alternata in vitro and to reveal related antifungal mechanisms through a metabolomics analysis. The results showed that the inhibitory effects of L-methionine (Met) treatment on mycelium growth, spore germination, and the germ tube elongation of A. alternata were enhanced with an increase in the Met concentration, but the inhibitory effects decreased when the Met concentration was higher than 50 mmolL-1. The results of propidium iodide staining and scanning electron microscopy showed that the Met treatment damaged the plasma membrane integrity of the A. alternata spores and caused an irreversible deformation of mycelium. In addition, after the Met treatment, the leakage of electrolytes, nucleic acid, and proteins in the A. alternata cells was significantly higher than that in the control group, indicating that the Met treatment increased the permeability of the cell membranes. Eighty-one different metabolites, divided into seven categories, were identified through the metabolomics analysis, including forty-three downregulated metabolites and thirty-eight upregulated metabolites. Among them, these differential metabolites were mainly involved in amino acid synthesis and metabolism, the pentose phosphate pathway, and the TCA cycle. Therefore, the antifungal effect of the Met treatment on A. alternata was mainly to damage the integrity of the cell membranes, make nucleic acid and protein contents leak, and affect the TCA cycle, carbohydrate metabolism, amino acid synthesis metabolism, and the metabolic pathways associated with cell membrane biosynthesis. Thus, the growth and development of A. alternata were inhibited. The research enriched the investigation of the effect of the antifungal mechanism of Met treatment on A. alternata and provided a theoretical basis for the application of Met to prevent and treat postharvest black spots in fruits and vegetables.

Alternaria brassicicola’ya karşı Trans-cinnamic Asit ve Xenorhabdus szentirmaii’nin Antifungal Metabolitlerinin Kullanım Potansiyellerinin Araştırılması

The, antifungal activities of trans-cinamic acid (TCA) and cell-free supernatant (CFS) of X. szentirmaii were evaluated against Alternaria brassicicola that cause Black spot disease. The results showed that TCA was more suppressive than CFS of X. szentirmaii in the control of A. brassicicola. In petri assays, the highest suppressive effect on spore germination was in TCA treatments compared to CFS of X. szentirmaii. Moreover, no germ tube elongation was observed in any of tested concentrations (0.25%, 0.50%, 1%, 2%) of TCA. The highest level of mycelial growth inhibitions (100% and 92%) were exhibited by TCA (2%) and TCA (1%), respectively. The curative and protective activity of TCA on disease severity of A. brassicicola were also evaluated on broccoli plants. In the curative activity assays, disease severities were 71.00%, 56.33% and 54.03% for control, TCA (1%) and TCA (2%), respectively. Whereas in the protective activity, TCA (2%) suppressed the disease severity significantly greater than TCA (1%). The disease severity of A. brassicicola after TCA application on broccoli plants was 25.21% and 17.37% for TCA (1%) and TCA (2%) respectively. Similar data were obtained in the efficacy of TCA on A. brassicicola. In the curative activity assays, TCA (1%) and TCA (2%) exhibited the efficacy with rates of 20.57% and 23.02%, respectively. However, TCA (2%) showed significantly higher efficacy than TCA (1%) in the protective activity. The current study provides that TCA has a great potential to suppress A. brassicicola and can be a good alternative to synthetic fungicides.

Carboxymethyl cellulose/Tween 80/Litsea cubeba essential oil nanoemulsion inhibits the growth of Penicillium digitatum and extends the shelf-life of ‘Shatangju’ mandarin

Penicillium digitatum (P. digitatum) is the primary pathogenic fungus responsible for postharvest citrus green mold, leading to a deterioration in fruit quality and significant economic losses. Litsea cubeba essential oil (LCEO) has gained widespread attention as a natural antifungal substance due to its high safety profile, non-resistance traits, and broad-spectrum antifungal activity. In this study, we prepared Litsea cubeba essential oil nanoemulsion (LCEO-NE) using Tween 80 and carboxymethyl cellulose (CMC) as emulsifiers through ultrasonic emulsification. The investigation delved into their stability, rheology, inhibitory activity against P. digitatum, and efficacy in preserving ‘Shatangju’ mandarin during storage. The results showed that the droplet size, polydispersity index, and zeta potential were 18.69 nm, 0.116, and −29.72 mV, respectively. LCEO-NE added with CMC and Tween 80 synergistically (LCEO-NE-CMC) have exhibited higher pH stability, ionic strength stability, thermal stability, storage stability, and centrifugal stability compared to LCEO-NE with Tween 80. In vitro fungistatic tests revealed that the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of LCEO-NE-CMC against P. digitatum were 1 μL mL−1 and 2 μL mL−1, respectively. LCEO-NE-CMC effectively inhibited mycelium growth, spore germination, and elongation of germ tubes. Scanning electron microscopy results demonstrated that LCEO-NE-CMC caused wrinkling and twisting of P. digitatum mycelium. Transmission electron microscopy results further revealed severe damage to the cell membrane, cytoplasm, and organelles, hindering mycelial growth. Furthermore, LCEO-NE-CMC treatment of ‘Shatangju’ mandarin significantly reduced weight loss and decay rate and delayed the decline in hardness and total soluble solids. In summary, LCEO-NE-CMC has been validated as a potent antifungal agent capable of extending the shelf life of ‘Shatangju’ mandarin.

The potentiality of Wickerhamomyces anomalus against postharvest black spot disease in cherry tomatoes and insights into the defense mechanisms involved

Our previous study revealed that Wickerhamomyces anomalus effectively inhibited Botrytis cinerea disease in cherry tomatoes. However, the potentiality of W. anomalus against black spot disease in cherry tomatoes as well as possible mechanisms related to this efficacy remain unclear. In our current study, we investigated the efficacy of W. anomalus against black spot disease in cherry tomatoes, and the molecular mechanisms related to disease-resistance response of W. anomalus treated cherry tomatoes were also investigated by transcriptome analysis. The results exhibited that W. anomalus successfully controlled postharvest black spot disease of cherry tomatoes caused by Alternaria alternata. Furthermore, W. anomalus vigorously controlled the spore germination and reduced the germ tube elongation of A. alternata. The physiological mechanisms by which W. anomalus inhibited the black spot decay in cherry tomatoes mainly through enhancing the ascorbate peroxidase (APX) and chitinase (CHI), and reducing the content of malondialdehyde (MDA). In addition, based on transcriptome technology, W. anomalus could up-regulate genes involved in several important KEGG pathways, including amino sugar and nucleotide sugar metabolism pathway, selenocompound metabolism pathway, linoleic acid metabolism pathway, and galactose metabolism pathway. These genes may help the fruit to enhance the enzyme activities and nutritional values of cherry tomatoes, synthesize the regulatory molecules in plant disease response as well as plant growth and development, increase the defense and oxidation resistance of the fruit during and after harvesting, and trigger ROS induced resistance in cherry tomatoes. Ultimately, W. anomalus has been proved as a biocontrol agent which could effectively control black spot disease in cherry tomatoes caused by A. alternata. This study can provide theoretical reference for the practical application of antagonistic yeasts in the biological control of postharvest diseases of cherry tomatoes.

Antifungal Activity of Extracts From the Ferulago Pauciradiata in Vitro Against Botrytis Cinerea Pers

This is the first study to reveal the antifungal properties of Ferulago pauciradiata plant. In this context investigated the effects of methanol (FPM), ethanol (FPE), hexane (FPH) and water (FPW) extracts of the F. pauciradiata plant on the prevention of losses caused by gray mold (Botrytis cinerea Pers) in vitro. The effects of FPM, FPE, and FPH 10, 25, 50, 100, 300, 500, 1000, and 2000 µL doses were determined by mycelium growth, germ tube elongation, and spore germination in vitro. The water extract didn’t show antifungal activity against B. cinerea. Compared to the control, both FPM and FPH caused 100% inhibition at the dose of 2000 µL by suppressing mycelial growth due to dose increases, while FPE had a 97.3% effect on the same parameter at the dose of 2000 µL. While there was no elongation at the 2000 µL dose of FPM and FPH, there was an elongation of 8.4 µm at the same dose of FPM. In spore germination, 0% germination was observed in FPM and FPH 2000 µL dose, while 17.5% germination was observed in FPE. These results show that F. pauciradiata extracts, which are of biological origin and are not environmentally toxic, are a good alternative for use in the control of B. cinerea.

The polyphenolic suberized peridermal skin of the Sikkim cucumber acts as an effective chemical barrier against Botrytis cinerea infection

Certain species of fleshy fruit that undergo skin cracking are capable of forming a specialized polyphenolic periderm to seal the wounded skin. Some of the genetic and metabolic components pertaining periderm formation have been identified, however it remains unknown if, and to what extent, this specialized tissue can act as an efficient barrier against the invasion of pathogenic fungi. We monitored the infection process of Botrytis cinerea on the cuticle-coated skin of the common cucumber (Cucumis sativus) or on the polyphenolic suberized peridermal skin of the Sikkim cucumber (C. sativus var. sikkimensis). In vivo inoculation assays inferred that while B. cinerea can successfully penetrate and form necrotic lesions on sativus fruit, it is incapable of penetrating the peridermal skin of sikkimensis fruit. Gas chromatography-mass spectrometry (GC-MS) profiling of fruit skin extracts, in vitro conidial germination and germ tube elongation assays, and qRT-PCR cutinase-encoding gene expression analyses, inferred that the accumulation of suberin monomers in the peridermal skin of sikkimensis fruit stimulate increased elongation of B. cinerea germ tubes and significantly alters the differential expression of cutinase-encoding genes. Among them, Bcin0607010, Bcin08g01580 and Bcin07g06480, three yet unidentified cutinases, whose expression is specifically increased in the presence of sikkimensis fruit skin extracts. Our data demonstrate that a polyphenolic suberized peridermal skin in cucumber fruit can shape the interactions with B. cinerea and implies that suberization of fleshy fruit may provide a means for reducing damage imposed by this and other pathogens.

Postharvest biocontrol of green mold (Penicillium digitatum) in citrus by Bacillus velezensis strain S161 and its mode of action

Green mold caused by Penicillium digitatum is a major postharvest disease of citrus that can result in significant losses during storage. Synthetic chemical fungicides typically used to control this disease have raised potential concerns regarding environmental pollution, human health, and the development of fungicide resistance. Biological control of postharvest diseases has been demonstrated to be an effective alternative to chemical control. In the present study, we investigated the postharvest biocontrol efficacy of Bacillus velezensis strain S161 against P. digitatum and its potential mechanisms of action. Results indicated that a cell-free supernatant (CFS) obtained from liquid culture of S161 strongly inhibited the mycelial growth, spore germination, and germ tube elongation of P. digitatum in vitro. The CFS effectively protected citrus fruit against P. digitatum, providing 95.6 % control. Further investigations revealed that the CFS degraded and ruptured hyphal membranes and spores and induced the excessive accumulation of reactive oxygen species (ROS) in hyphal cells resulting in oxidative damage. CFS exposure also resulted in the downregulation of genes associated with spore germination, growth, reproduction, and virulence. antiSMASH analysis of biosynthetic gene clusters (BGCs) in B. velezensis indicated that B. velezensis possesses several core clusters, encoding the synthesis of surfactin, bacillomycin D, fengycin, bacilysin, bacillibactin, macrolactin, difficidin, bacillaene, and amylocycicin. Further analysis using Liquid Chromatography Tandem Mass Spectrometry (LC-MS) revealed the presence of four of these metabolites (surfactin, iturin, fengycin, and bacillibactin) in the CFS of B. velezensis. Additional bioassays conducted in sealed plates revealed that volatile organic compounds (VOCs) produced by S161 also inhibited the growth of P. digitatum. A total of 24 VOCs were found to be produced by S161 using headspace solid-phase microextraction/gas chromatography-mass spectrometry (HS-SPME/GC-MS). The identified VOCs were mainly ketones and alcohols. Collectively, our results indicate that B. velezensis strain S161 is an effective biocontrol agent of P. digitatum on citrus and inhibits pathogen germination and growth through a range of mechanisms, including the downregulation of genes associated with spore germination and growth, induction of oxidative stress, and the antimicrobial activity of VOCs.

Phenyl tetramethyl cyclopropane carboxamide class: New broad-spectrum postharvest fungicides

Fresh postharvest fruit and vegetable loss due to the development of postharvest diseases is enormous. Synthetic fungicides are the primary and most effective tool to control postharvest disease caused by fungal pathogens. However, broad-spectrum synthetic fungicides possess a high risk to the environment and human health. Therefore, in recent years many authorized fungicides have been banned or their permitted maximal residue levels were reduced. Hence, there is a need to develop new compounds with low toxicity and antifungal properties. In the current study, 13 compounds from the Aromatic-tetramethyl-cyclopropane-carboxamide (PTCC) class that have no neurotoxicity were screened for possible antifungal activity. Three of the tested compound (JS-2, JS-9, and JS-10) significantly reduced the growth of Botrytis cinerea, Penicillium expansum, and Colletorichum gloeosporioides, three major postharvest pathogens, and reduced B. cinerea germ tube elongation. The initial mode of action studies revealed that the PTCC increased fungal membrane polarity, indicating the induction of changes in the membrane composition. Additionally, JS-2 increased the mitochondrial membrane potential and ATP production, which hinders the fungal respiratory activity by a possible interference with the proton pump in the mitochondria. JS-9 reduced ROS, and ATP production, which suggests interference with metabolic activity. The third compound JS-10, reduced fungal viability, however, more study is needed to identify the specific metabolic pathway that is affected. Furthermore, the PTCC compounds reduced decay development in mango, apple fruit, and grape berries. The greatest effect was observed in the pathosystem of B. cinerea-grape. Overall, the results of the current study emphasize the potential of the new PTCC class compounds as new fungicides.