Control Of Postharvest Diseases Research Articles

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.

Induced resistance to control postharvest stem-end rot by methyl jasmonate in mango fruit

Induced resistance is an alternative disease control strategy for postharvest fruits and vegetables. Methyl jasmonate (MeJA) is a crucial phytohormone in the defense response to biotic and abiotic stresses. The effect and relevant mechanism of MeJA on the control of postharvest disease in mango fruit remain unclear. This study investigated the effect and possible mechanism of MeJA against stem-end rot caused by Lasiodiplodia theobromae in mango fruit. The results showed that MeJA significantly inhibited the lesion expansion on mango fruit inoculated with L. theobromae. 10 μM MeJA treatment effectively induced disease resistance against L. theobromae during postharvest storage. MeJA enhanced the activities of defense-related enzymes, including phenylalanine ammonia lyase (PAL), peroxidase (POD), β-1,3-glucanase (GLU), and chitinase (CHT), increased the accumulation of endogenous jasmonic acid (JA) and salicylic acid (SA) contents, up-regulated the expressions of the related genes on JA pathway (AOS, JAR1, MYC2, and COI1) and SA pathway (ICS, and PR1), stimulated the contents of total phenolics and flavonoids, and inhibited the accumulation of malondialdehyde (MDA). Furthermore, MeJA delayed the ripening and senescence of the fruit by inhibiting the peel yellowing, flesh softening and change in soluble solids content (SSC) of mango fruit. The results indicated that the enhanced resistance of MeJA-treated mango to stem-end rot was potentially due to the activation of defense responses induced by synergistic interaction between JA and SA pathways, as well as delayed postharvest ripening. The MeJA treatment is a promising strategy to control stem-end rot of mango fruit.

Molecular and metabolic insights into the mechanism of exogenous methyl jasmonate in enhancing the postharvest resistance of kiwifruit to Botrytis cinerea

Gray mold, caused by Botrytis cinerea infection, significantly impacts postharvest kiwifruit, leading to spoilage and food safety issues. Meanwhile, methyl jasmonate (MeJA) induces defense responses in plants. This study aimed to identify the optimal MeJA concentration to induce disease resistance in kiwifruits. Notably, various plant defense enzymes were detected in MeJA-treated kiwifruit. Moreover, 0.01 mol/L MeJA was found to enhance B. cinerea resistance in kiwifruit by increasing antioxidant enzyme activity. Widely targeted metabolomics analysis revealed 62–64 differentially expressed metabolites (DEMs) between the different treatment groups. Additionally, RNA-seq analysis revealed 930–2900 differentially expressed genes (DEGs), between these groups. Subsequently, combined DEG and DEM analysis highlighted phenylpropanoid biosynthesis and plant hormone signaling as key transduction pathway associated with MeJA-induced resistance. Overall, these findings identified the mechanism of MeJA-induced resistance in kiwifruit, providing a theoretical basis for the safe and effective control of postharvest diseases in kiwifruit.

Biocontrol of Fusarium oxysporum-infested Gastrodia elata Bl. by Lactobacillus curvatus 2768-VOCs and mechanism of inhibition

Gastrodia elata Bl. Is susceptible to infestation by the fungus Fusarium oxysporum, which can cause severe post-harvest diseases. This paper presents the findings of an investigation into the control and bacteriostatic mechanisms of Lactobacillus curvatus 2768-VOCs on F. oxysporum-infected G. elata. The results of both in vitro and in vivo tests demonstrated that L. curvatus 2768-VOCs exhibited inhibitory effects against F. oxysporum, with inhibition rates of 63.37% and 44.4%, respectively. The results of the in vivo test also demonstrated that the pre-fumigation approach exhibited superior efficacy compared to direct fumigation, with the former showing a preventive effect. Furthermore, it was discovered that VOCs disrupted the integrity of F. oxysporum cell membranes and altered their permeability, resulting in the leakage of cell contents. The fumigation caused damage to the mycelial structure, accompanied by a notable decline in the total lipid and ergosterol content, and an appreciable increase in MDA content. Moreover, the fumigation of VOCs markedly diminished the activities of ATPase and mitochondrial dehydrogenase, thereby disrupting the respiration of F. oxysporum and its energy metabolism. The VOCs were subjected to GC-MS analysis, which revealed that the relative content of acids was the highest, particularly formic acid and glyoxalic acid. The study offers a theoretical basis for the biological control of postharvest diseases in G. elata.

Characterizations of the pullulan/sodium alginate coatings incorporated with sodium silicate and EDTA-2Na and the antifungal effect on citrus green mold

Citrus has suffered great losses from postharvest fungal diseases. The strategy of polysaccharide-based coating combined with antimicrobial salts was introduced to preserve citrus and control green mold. Sodium silicate and ethylene diamine tetraacetic acid-2Na (EDTA-2Na) (SE) were incorporated with pullulan (PUL)/sodium alginate (SA) solutions to fabricate PSA-SE systems. The results indicated that the PSA-SE films had good biocompatibility based on hydrogen bonds and showed uniform and dense. The molecular of PUL and SA were assembled through entanglement to form a network structure and the surface roughness of the PSA-SE films increased with the addition of SA. The P3SA2-SE film indicated appropriate tensile strength and elongation at break, as well as the lowest water vapor permeability. The carbon dioxide and oxygen permeability and dissolution of P3SA2-SE film were at low values. The P3SA2-SE film had the highest water contact angle (66°). With the addition of SA, the absorbance of the PSA-SE films increased, which was conducive to light blocking. The antifungal experiments revealed that the P3SA2-SE coating showed a significant effect on controlling citrus green mold, especially in Citrus sinensis Osbeck ‘Lane Late’ almost completely inhibited Penicillium digitatum (P44). This study will promote the development of citrus postharvest disease control.

Antifungal activity of Bacillus velezensis and Pseudomonas azotoformans isolated from compost tea against anthracnose (Colletotrichum spp.) on strawberry fruit

AbstractAnthracnose, caused by Colletotrichum spp., is a threat to strawberry production globally. Unlike their chemical counterparts, microbial biofungicides offer a method of postharvest fungal disease control that is safe, sustainable and less affected by pathogen resistance. The present study evaluated the antifungal effects of three bacteria, Bacillus velezensis strains SH1 and SH2 and Pseudomonas azotoformans strain SH3, obtained from sheep manure compost tea. The bacteria or their cell‐free filtrates were tested against Colletotrichum acutatum and Colletotrichum gloeosporioides in bioassays and against strawberry anthracnose. In addition, precipitated or extracted extracellular fractions were tested to determine the effects on membrane permeability of Colletotrichum spp. spores. Confrontation assay results showed all bacteria inhibited mycelial growth, with B. velezensis SH1 and P. azotoformans SH3 being the most effective. All cell‐free filtrates inhibited mycelial growth with B. velezensis SH1 and SH2 resulting in the highest inhibition. The bacteria suppressed anthracnose lesions on strawberry fruit although effective treatments varied by causal mould. B. velezensis SH1 and SH2 significantly permeabilized spore membranes, indicating antibiosis as a possible mode of action. Investigation into antimicrobial compound production found various homologues of the lipopeptides fengycin, iturin and surfactin were produced by B. velezensis SH1 and SH2. Results suggest that lipopeptides produced by B. velezensis strains permeabilize Colletotrichum cell membranes, and that fengycins were the most inhibitory of the lipopeptides against Colletotrichum spp.

Postharvest disease, latent infection, and preharvest control of ‘Shine-Muscat’ grapes

The cultivation of ‘Shine-Muscat’ grape variety is rapidly expanding in East Asia due to its exceptional qualities favored by consumers. However, studies on the disease pathogens affecting this variety and how to control them remain limited. This study focuses on investigating postharvest diseases that impact ‘Shine-Muscat’ grapes and explores potential prevention methods, with regional emphasis on Shanghai metropolitan area, a key market for edible grapes in China. Common market diseases such as Alternaria spot, grey mold, and Aspergillus rot are frequently found in ‘Shine-Muscat’ grapes, accounting for 29.2%, 20.4%, and 16.7% of diagnostic cases, respectively. The study revealed that Alternaria spp., Cladosporium spp., and Botrytis cinerea could attach to or invade grape fruits during the flowering, young fruit, and veraison stages of ‘Shine-Muscat’. In contrast to conventional open field cultivation methods, the rain-shelter and root restriction cultivation can aid in reducing fruit disease incidence during production, and thus alleviate the postharvest disease risks. Moreover, the application of calcium propionate during fruit development stages could efficiently manage both in-field and post-harvest diseases, and extend storage life of harvested fruit.

Efficacy of Essential Oil Vapours in Reducing Postharvest Rots and Effect on the Fruit Mycobiome of Nectarines.

Nectarines can be affected by many diseases, resulting in significant production losses. Natural products, such as essential oils (EOs), are promising alternatives to pesticides to control storage rots. This work aimed to test the efficacy of biofumigation with EOs in the control of nectarine postharvest diseases while also evaluating the effect on the quality parameters (firmness, total soluble solids, and titratable acidity) and on the fruit fungal microbiome. Basil, fennel, lemon, oregano, and thyme EOs were first tested in vitro at 0.1, 0.5, and 1.0% concentrations to evaluate their inhibition activity against Monilinia fructicola. Subsequently, an in vivo screening trial was performed by treating nectarines inoculated with M. fructicola, with the five EOs at 2.0% concentration by biofumigation, performed using slow-release diffusers placed inside the storage cabinets. Fennel, lemon, and basil EOs were the most effective after storage and were selected to be tested in efficacy trials using naturally infected nectarines. After 28 days of storage, all treatments showed a significant rot reduction compared to the untreated control. Additionally, no evident phytotoxic effects were observed on the treated fruits. EO vapors did not affect the overall quality of the fruits but showed a positive effect in reducing firmness loss. Metabarcoding analysis showed a significant impact of tissue, treatment, and sampling time on the fruit microbiome composition. Treatments were able to reduce the abundance of Monilinia spp., but basil EO favored a significant increase in Penicillium spp. Moreover, the abundance of other fungal genera was found to be modified.

Enhancing biological control of postharvest green mold in lemons: Synergistic efficacy of native yeasts with diverse mechanisms of action.

Argentina is among the most important lemon fruit producers in the world. Penicillium digitatum is the primary lemon fungal phytopathogen, causing green mold during the postharvest. Several alternatives to the use of synthetic fungicides have been developed, being the use of biocontrol yeasts one of the most promising. Although many of the reports are based on the use of a single yeast species, it has been shown that the combination of agents with different mechanisms of action can increase control efficiency through synergistic effects. The combined use of native yeasts with different mechanisms of action had not been studied as a biological control strategy in lemons. In this work, the mechanisms of action of native yeasts (Clavispora lusitaniae AgL21, Clavispora lusitaniae AgL2 and Clavispora lusitaniae AcL2) with biocontrol activity against P. digitatum were evaluated. Isolate AgL21 was selected for its ability to form biofilm, colonize lemon wounds, and inhibit fungal spore germination. The compatibility of C. lusitaniae AgL21 with two killer yeasts of the species Kazachstania exigua (AcL4 and AcL8) was evaluated. In vivo assays were then carried out with the yeasts applied individually or mixed in equal cell concentrations. AgL21 alone was able to control green mold with 87.5% efficiency, while individual killer yeasts were significantly less efficient (43.3% and 38.3%, respectively). Inhibitory effects were increased when C. lusitaniae AgL21 and K. exigua strains were jointly applied. The most efficient treatment was the combination of AgL21 and AcL4, reaching 100% efficiency in wound protection. The combination of AgL21 with AcL8 was as well promising, with an efficiency of 97.5%. The combined application of native yeasts showed a synergistic effect considering that the multiple mechanisms of action involved could hinder the development of green mold in lemon more efficiently than using single yeasts. Therefore, this work demonstrates that the integration of native yeasts with diverse modes of action can provide new insights to formulate effective microbial consortia. This could lead to the development of tailor-made biofungicides, allowing control of postharvest fungal diseases in lemons while remaining competitive with traditionally used synthetic chemicals.

Evalution of co-culture system on Debaryomyces hansenii and Bacillus atrophaeus strains and its efficacy on disease control and quality maintenance of postharvest fruit

Microbial antagonists are used to manage both pre- and postharvest diseases of fruit crops. Mixing two types of antagonists has been reported to enhance the viability, stability, and biocontrol efficacy of each strain used individually. In the present study, a co-cultivation system for Debaryomyces hansenii (Y-1) and Bacillus atrophaeus (TE-7) strains was evaluated, and the regulatory mechanism associated with antagonistic activity and postharvest disease control in mango and litchi fruits was investigated. Results indicated that the optimized co-cultivation system for Y-1 and TE-7 (Y + T) significantly promoted the growth of both strains, compared to single cultures, and improved their ability to adapt to co-cultivation conditions. Non-targeted metabolomics revealed that characteristic metabolites, including N-Acetyl-L-glutamic acid, adenine, umbelliferone, and cucurbitacin B significantly accumulated in co-culture, which involved in citrate cycle (TCA cycle), amino acid biosynthesis, phenylpropanoid biosynthesis, and alkaloid biosynthesis. Subsequent in vivo and in vitro assays indicated that the Y + T system, relative to the use of the individual strains, significantly enhanced the inhibition of pathogen growth, increased disease control, and also decreased weight loss and changes in peel color. The co-culture also enhanced the content of total acids (TA) and total soluble solids (TSS) in mango and litchi fruits compared to the control group. These results suggest that the Y + T co-cultivation system is highly effective in antagonistic protection, disease control, and quality maintenance of postharvest fruit. Our study provides new insights into the interactions that occur between biocontrol microorganisms in a co-culture system, and information that can be used for the development of improved strategies for the postharvest preservation of fruit.

Endophytic Stenotrophomonas geniculata KJ-6 via producing antifungal volatile organic compounds effectively control Lanzhou lily postharvest diseases

The endophytic bacterial Stenotrophomonas geniculata KJ-6, was isolated from Arisaematis rhizoma. This strain has the ability to control three postharvest pathogenic fungi of Lanzhou lily (Trichoderma lixii F-2, Talaromyces tumuli F-3, and Fusarium annulatum F-6) by releasing volatile organic compounds (VOCs). The experiment utilized the double-layer sealed bottom plate method. The results demonstrate that KJ-6 effectively inhibits the mycelial growth of F-2, F-3, and F-6, with inhibition rates of 81.59%, 79.87%, and 84.7%, respectively. Moreover, scanning electron microscopy (SEM) revealed abnormal mycelium morphology in the test pathogenic fungi treated with KJ-6 VOCs, characterized by multiple wrinkles, cracks, and distortions. Using five common phytopathogenic fungi as controls, our results demonstrated that the VOCs from KJ-6 exhibited broad-spectrum antifungal effects. Analysis using headspace gas chromatography-ion mobility spectrometry identified three components of the VOCs produced by KJ-6, including 1-propanethiol, isoamyl acetate, and 2-methyl-1-butanol. Antifungal tests revealed that 1-propanethiol plays a crucial role in the inhibitory activity of VOCs. It exhibited inhibitory rates of 64.17%, 72.73%, and 26.71% on the mycelium growth of F-2, F-3, and F-6, respectively. In vivo experiments further confirmed that VOCs can significantly reduce the disease index and decay rate of Lanzhou lily bulbs during storage. Moreover, KJ-6 treatment led to a significant reduction in the degree of browning of lily bulbs. Additionally, it enhanced the activity of defense-related enzymes, improved disease resistance, and extended the shelf life of lily bulbs. As a result, this study offers a theoretical foundation for the biological control of postharvest diseases in Lanzhou lily.

Potentiation effect of the AI-2 signaling molecule on postharvest disease control of pear and loquat by Bacillus amyloliquefaciens and its mechanism

An autoinducer-2 (AI-2) signaling molecule from Bacillus was synthesized, and its mechanism on the biofilm formation and biocontrol ability of B. amyloliquefaciens was verified in vitro and in vivo. The 16S/ITS amplicon sequencing was used to analyze the effect of B. amyloliquefaciens B4 with or without AI-2 on the microflora of pears during storage. The results showed that B. amyloliquefaciens B4 secreted AI-2, which promoted biofilm formation. Additionally, AI-2 at a concentration of 40 μmol/L enhanced the biocontrol ability of B. amyloliquefaciens B4 on postharvest pear and loquat fruits. Finally, amplicon sequencing demonstrated that the addition of AI-2 increased the abundance of B. amyloliquefaciens B4 in fruit by stimulating the growth and biofilm formation of this bacterium.

Genetic identification, pathogenicity and patulin production of Penicillium species from apple blue mold in China

Abstract Objectives Blue mold is a common postharvest disease that leads to severe rot and patulin (PAT) contamination in fruits, which is a key factor endangering the storage and quality of apple products. However, the Penicillium species from apple blue mold in China and their pathogenicity and PAT production ability have not been well studied. Materials and Methods In this study, 62 strains of pathogenic Penicillium species were isolated from blue mold apples collected from different regions of China. The ITS, BenA, and CaM genes were sequenced for molecular identification. Results Penicillium strains were identified as three species, 57 P. expansum, 3 P. crustosum, and 2 P. polonicum. Twelve variants of the ITS sequence, 61 variants of BenA and 67 variants of CiaM genes were identified between Penicillium species. Fungal morphology was observed on potato dextrose agar (PDA). After 10 d of cultivation, P. expansum cultures were detected with PAT concentrations ranging from 457.98 to 1333.85 mg/kg, and two P. polonicum strains were 6.02 mg/kg and 6.30 mg/kg. The three P. crustosum strains could not produce PAT on PDA. In apple inoculation, P. expansum strains showed significantly faster infection rates than P. crustosum and P. polonicum strains. All P. expansum strains can produce PAT during infection, and the concentrations in the rot apple tissues were 2.31–88.67 mg/kg. The P. crustosum and P. polonicum strains could not produce PAT during infection. Conclusions This study provides data and information regarding the morphology, virulence and PAT production of Penicillium pathogens that will improve the understanding of apple blue mold and postharvest disease control.

Transcriptomic analysis reveals the resistance mechanism of flavonoids from Sedum aizoon L. to Rhizopus nigricans in postharvest strawberry fruit

Strawberry (Fragaria × ananassa) is one of the most popular fruits worldwide, rich in vitamins and with extremely high nutritional value. However, the postharvest diseases of strawberries caused by pathogenic fungi reduced the commercial value and caused serious economic losses. Rhizopus nigricans (R. nigricans) is one of the fungal pathogens causing huge economic losses and potential food safety problems. Flavonoids from Sedum aizoon L. (FSAL) is an herbal medicine reported to have fungicidal activity. In this study, strawberries were treated with FSAL, analyzed the incidence and fruit quality, and their antioxidant enzymes, such as ascorbate peroxidase (APX), catalase (CAT), polyphenol oxidase et al. (PPO), and peroxidase (POD). The results showed that exogenous FSAL treatment (especially at 30 h) enhanced strawberry resistance to R. nigricans, reduced disease incidence, maintained better fruit quality, and exhibited higher pathogen resistance-related defense enzyme activities. Further transcriptomic analysis of samples treated for 30 h revealed a total of 710 genes responsive to FSAL, and there were 510 and 200 genes identified as being substantially upregulated and downregulated, respectively. KEGG analysis indicated that FSAL treatment induced resistance in strawberry in relation to phenylpropanoid biosynthesis, glutathione metabolism, and amino acid metabolism-related changes. The results of this study may reveal the mechanism of FSAL-induced resistance in strawberry and provide new theoretical foundation for the safe and efficient control of postharvest diseases in strawberry.

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 and mechanism of chitosan against Fusarium solani caused ginger soft rot during postharvest storage

Postharvest rot caused by Fusarium solani (F. solani) results in enormous economic loss to the global vegetables industry. Chitosan has been shown to be effective in control postharvest diseases of vegetables, but the specific mechanism of chitosan on F. solani has not been studied. In this study, we evaluated antifungal activity of chitosan against F. solani caused soft rot in vitro and in vivo. Antifungal assay results showed that chitosan significantly inhibited the mycelial growth and spore germination of F. solani. Simultaneously, chitosan showed disruptive activity on the mycelial morphology and cell membrane, which were achieved by decreasing intracellular sugars, proteins and lipids content. Furthermore, chitosan treatment significantly decreased tricarboxylic acid (TCA)-related enzymes activity, reducing the number of metabolites in the TCA cycle. UPLC-Triple-TOF/MS-based metabolomics analysis showed that chitosan interferes with fungal metabolic pathways, mainly related to energy metabolism, lipid metabolism and sugar metabolism. Exogenous α-D-glucose and linoleic acid treatment promoted mycelia growth, verifying the sugar catabolism and TCA cycle was involved in the inhibition of chitosan against F. solani. The in vivo study showed that chitosan treatment effectively reduced disease rate and severity of postharvest soft rot through activating the biochemical defense response and modulating the expression of phytopathogenic responses LysM genes. These results contribute to explore the underlying mechanisms of chitosan against F. solani.

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.

Cardamom oil-infused paper box: Enhancing rambutan fruit post-harvest disease control with reusable packaging

The research aimed to develop a paper box with 10–300 μl of cardamom oil to improve rambutan storage, reduce waste, and explore reuse possibilities. The experiment investigated the delay in mold growth caused by the post-harvest disease, Pestalotiopsis sp., both on the medium and on rambutan fruit under storage conditions of 10 ± 2 °C and approximately 80% RH. The results showed that CM at 300 μl significantly inhibited Pestalotiopsis sp. mycelium and spore germination on the medium, while a lower volume of 30 μl effectively delayed mold incidence on rambutan during the 14-day storage period. The confirmed antifungal mode of action indicated that CM disrupted Pestalotiopsis sp. ergosterol and cell membrane integrity, resulting in mycelium lysis and damaged morphology, thereby inhibiting its growth. The active fruit box can be reused for at least 2 or 3 storage cycles, effectively delaying rambutan decay and preserving its color change parameters. By using the box with 30 μl of CM, rambutan's shelf-life was extended to 14 days compared to the control's shelf-life of around 7 days. Active paper boxes offer a valuable solution for improving post-harvest fruit storage and transportation, benefiting both farmers and consumers.

The 2′,4′-Dichloro-chalcone Inhibits the In Vitro Growth and Pathogenicity of Fusarium tricinctum and Trichothecium roseum by Activating Cyanide-Resistant Respiration

Chalcones are a class of flavonoids possessing antimicrobial properties and have potential for use as coatings of plant products for the control of postharvest diseases. The effects of 2′,4′-dichloro-chalcone on the in vitro growth and in vivo pathogenicity of Fusarium tricinctum and Trichothecium roseum were investigated. First, 1 µM of 2′,4′-dichloro-chalcone strongly inhibited the mycelial growth and conidial production of F. tricinctum (32.3%) and T. roseum (65.2%) in vitro. Meanwhile, the cell membrane permeability was increased by 25% and 22.5% and the accumulation of reactive oxygen species was increased by 41.7 and 65.4%, respectively, of F. tricinctum and T. roseum. This treatment also significantly inhibited the total respiration rate and activated the cyanide-resistant respiratory pathway in both pathogens. The expression level of AOX was enhanced in F. tricinctum and T. roseum by 52.76 and 39.13%, respectively. This treatment also significantly inhibited the expansion of potato dry rot from F. tricinctum (48.6%) and apple rot spot from T. roseum (36.2%). Therefore, 2′,4′-dichloro-chalcone has potential use as an alternative safety method in the control of postharvest diseases by F. tricinctum and T. roseum in agricultural practices.

Antifungal activity of volatile organic compounds from essential oils against the postharvest pathogens Botrytis cinerea, Monilinia fructicola, Monilinia fructigena, and Monilinia laxa.

Gray mold and brown rot, caused respectively by Botrytis cinerea and Monilinia spp., are fungal diseases responsible for significant losses during the storage of fruit and vegetables. Nowadays, the control of postharvest diseases is shifting towards more sustainable strategies, including the use of plant secondary metabolites. In this study, the antifungal activity of Origanum vulgare, Thymus vulgaris, Thymus serpyllum, Melaleuca alternifolia, Lavandula officinalis, Lavandula hybrida, Citrus bergamia, Rosmarinus officinalis, Cinnamomum zeylanicum essential oils (EOs) in vapor phase was tested in vitro against B. cinerea, Monilinia fructicola, Monilinia fructigena, and Monilinia laxa. For the experiments, a protocol using a volatile organic compounds (VOC) chamber was designed. Results indicate a dose-dependent inhibitory activity of all the tested EOs, with O. vulgare, T. vulgaris, and T. serpyllum being the most active ones, with minimum inhibitory concentrations (MIC) of 22.73, 45.45, and 22.73 µl/L, respectively, against B. cinerea and a range between 5.64 and 22.73 µl/L against the three Monilinia spp. Overall, B. cinerea presented lower sensitivity to vapor-phase EOs than any of the Monilinia strains, except for the C. zeylanicum EO, which consistently showed higher inhibition against B. cinerea. Among the three Monilinia spp., M. fructicola was the least sensitive, while M. fructigena was the most sensitive. The use of VOC chambers proved to be a reliable protocol for the assessment of antimicrobial activities of EOs. These results suggest that the VOC emitted by the tested EOs are effective towards important decay-causing fungi, and that they could be used for the control of gray mold and brown rot in in vivo trials.