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Anthracnose caused by Colletotrichum scovillei is a significant disease of pepper, including in postharvest stage. Bacillus species represent a potential microbial resource for controlling postharvest plant diseases. Here, a strain HG-8-2 was obtained and identified as Bacillus velezensis through morphological, biochemical, physiological, and molecular analyses. The culture filtrate showed highly antifungal activity against C. scovillei both in vitro and on pepper fruit. Crude lipopeptide extracts, which had excellent stability, could effectively inhibit mycelial growth of C. scovillei with an EC50 value of 28.48 ± 1.45 µg mL-1 and inhibited conidial germination. Pretreatment with the extracts reduced the incidence and lesion size of postharvest anthracnose on pepper fruit. Analysis using propidium iodide staining, malondialdehyde content detection and scanning electron microscope observation suggested that the crude lipopeptide extracts harbored antifungal activity by damaging cell membranes and mycelial structures. The RNA-seq analysis conducted on C. scovillei samples treated with the extracts, as compared to untreated samples, revealed significant alterations in the expression of multiple genes involved in protein biosynthesis. Overall, these results demonstrated that B. velezensis HG-8-2 and its crude lipopeptide extracts exhibit highly antagonistic ability against C. scovillei, thereby offering an effective biological agent for the control of anthracnose in pepper fruit.

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Background: Botrytis cinerea a blueberry gray mold, is one of the main diseases affecting postharvest storage, causing significant losses. Several studies have shown that Bacillus tequilensis can prevent the growth of plant pathogens by producing various antibacterial substances, and can induce plant resistance. However, research on the biological management of post-harvest gray mold in blueberries using B. tequilensis remains unclear. Methods: To better control the postharvest gray mold of blueberry, the effects of B. tequilensis KXF6501 fermentation solution (YY) and KXF6501 cell-free supernatant (SQ) on the induction of disease resistance in blueberry fruits were studied using biochemical and transcriptomic analyses. Results: We found that YY controlled the conidial germination and mycelial growth of B. cinerea in vitro, followed by SQ. After 3 d of culture, the lesion diameter and incidence of gray mold in blueberry fruits inoculated with YY and SQ were smaller than those in the control group. Therefore, gray mold in blueberries was effectively controlled during the prevention period, and the control effect of YY was better than that of SQ. Transcription spectrum analysis of blueberry peel tissue showed that the YY- and SQ-induced phenylpropane metabolic pathways had more differentially expressed genes (DEGs) than other biological pathways. In addition, biochemical analyses showed that YY treatment effectively enhanced the activity of enzymes related to the phenylpropane pathway (phenylalanine ammonialyase [PAL], cinnamate 4-hydroxylase [C4H], 4-coumarate CoA ligase [4CL], and polyphenol oxidase [PPO]) and stimulated the synthesis of lignin, total phenols, and flavonoids, followed by SQ. Compared with the control, the YY and SQ treatments reduced the weight loss rate and better maintained the appearance and nutritional quality of the blueberry fruits. Conclusion: Our findings suggest that B. tequilensis KXF6501 is potentially useful as a suitable bio-control agent in harvested blueberries.

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In this study, antagonistic endophytic fungi were isolated from postharvest chestnut fruits; endophytic antagonistic fungi and their combination of inhibitory effects on the fungal pathogen Neofusicoccum parvum were evaluated. A total of 612 endophytic fungi were isolated from 300 healthy chestnut kernels, and 6 strains out of them including NS-3, NS-11, NS-38, NS-43, NS-56, and NS-58 were confirmed as antagonistic endophytic fungi against Neofusicoccum parvum; these were separately identified as Penicillium chermesinum, Penicillium italicum, Penicillium decaturense, Penicillium oxalicum, Talarmyces siamensis, and Penicillium guanacastense. Some mixed antagonistic endophytic fungi, such as NS-3-38, NS-11-38, NS-43-56, and NS-56-58-38, exhibited a much stronger antifungal activity against N. parvum than that applied individually. Among them, the mixture of NS-3-38 showed the highest antifungal activity, and the inhibition rate was up to 86.67%. The fermentation broth of NS-3, NS-38, and their combinations exhibited an obvious antifungal activity against N. parvum, and the ethyl acetate phase extract of NS-3-38 had the strongest antifungal activity, for which the inhibitory rate was up to 90.19%. The NS-3-38 fermentation broth combined with a chitosan coating significantly reduced N. parvum incidence in chestnuts from 100% to 19%. Furthermore, the fruit decay and weight loss of chestnuts during storage were significantly decreased by the NS-3-38 fermentation broth mixture along with a chitosan coating. Therefore, a mixture of P. chermesinum and P. decaturense could be used as a potential complex biocontrol agent to control postharvest fruit decay in chestnuts.

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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.

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Ethylene produced by plants generally induces ripening and promotes decay, whereas the effect of ethylene produced by pathogens on plant diseases remains unclear. In this study, four ethylene-producing fungi including Alternaria alternata (A. alternata, Aa), Fusarium verticilliodes (F. verticillioides, Fv), Fusarium fujikuroi 1 (F. fujikuroi 1, Ff-1) and Fusarium fujikuroi 2 (F. fujikuroi 2, Ff-2) were severally inoculated in potato dextrose broth (PDB) media and postharvest green peppers, the ethylene production rates, disease indexes and chlorophyll fluorescence parameters were determined. The results showed that Ff-2 and Fv in the PDB media had the highest and almost the same ethylene production rates. After inoculation with green peppers, Ff-2 treated group still exhibited the highest ethylene production rate, whereas Aa treated group had a weak promotion effect on ethylene production. Moreover, the ethylene production rate of green peppers with mechanical injury was twice that without mechanical injury, and the ethylene production rates of green peppers treated with Aa, Ff-1, Ff-2 and Fv were 1.2, 2.6, 3.8 and 2.8 folds than those of green peppers without treatment, respectively. These results indicated that pathogen infection stimulated the synthesis of ethylene in green peppers. Correlation analysis indicated that the degreening of Fusarium-infected green pepper was significantly positively correlated with the ethylene production rate of green pepper, whereas the disease spot of Aa-infected green pepper had a significant positive correlations with the ethylene production rate of green peppers. Chlorophyll fluorescence results showed that the green peppers already suffered from severe disease after being infected with fungi for 4 days, and Fusarium infection caused early and serious stress, while the harm caused by A. alternata was relatively mild at the early stage. Our results clearly showed that α-keto-γ-methylthiobutyric acid (KMBA)-mediated ethylene synthesis was the major ethylene synthesis pathway in the four postharvest pathogenic fungi. All the results obtained suggested that ethylene might be the main infection factor of Fusarium spp. in green peppers. For pathogenic fungi, stimulating green peppers to produce high level of ethylene played a key role in the degreening of green peppers.

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Postharvest rot, caused by Penicillium expansum, in tomatoes poses significant economic and health risks. Traditional control methods, such as the use of fungicides, raise concerns about pathogen resistance, food safety, and environmental impact. In search of sustainable alternatives, plant secondary metabolites, particularly phenolic compounds and their derivatives, have emerged as promising natural antimicrobials. Among these, feruloyl glyceride (FG), a water-soluble derivative of ferulic acid, stands out due to its antioxidant properties, antibacterial properties, and improved solubility. In this study, we provide evidence demonstrating FG is capable of inhibiting the spore germination of P. expansum and effectively reducing the incidence rate of Penicillium rot of tomatoes, without compromising quality. Electron microscopy observations combined with metabolite and transcriptomic analyses revealed that FG treatments resulted in enhanced suberin accumulation through promoting the expression of suberin synthesis related genes and, consequently, inhibited the growth and expansion of P. expansum on the fruits. This work sheds light on the mechanisms underlying FG's inhibitory effects, allowing its potential application as a natural and safe alternative to replace chemical fungicides for postharvest preservation.

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The plant hormone ethylene plays a critical role in fruit defense against Botrytis cinerea attack, but the underlying mechanisms remain poorly understood. Here, we showed that ethylene response factor SlERF.C1 acts as a key regulator to trigger the ethylene-mediated defense against B. cinerea in tomato fruits without compromising ripening. Knockout of SlERF.C1 increased fruit susceptibility to B. cinerea with no effect on ripening process, while overexpression enhanced resistance. RNA-Seq, transactivation assays, EMSA and ChIP-qPCR results indicated that SlERF.C1 activated the transcription of PR genes by binding to their promoters. Moreover, SlERF.C1 interacted with the mitogen-activated protein kinase SlMPK8 which allowed SlMPK8 to phosphorylate SlERF.C1 at the Ser174 residue and increases its transcriptional activity. Knocking out of SlMPK8 increased fruit susceptibility to B. cinerea, whereas overexpression enhanced resistance without affecting ripening. Furthermore, genetic crosses between SlMPK8-KO and SlERF.C1-OE lines reduced the resistance to B. cinerea attack in SlERF.C1-OE fruits. In addition, B. cinerea infection induced ethylene production which in turn triggered SlMPK8 transcription and enhanced the phosphorylation of SlERF.C1. Overall, our findings reveal the regulatory mechanism of the 'Ethylene-MPK8-ERF.C1-PR' module in resistance against B. cinerea and provide new insight into the manipulation of gray mold disease in fruits.

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Brown rot, aspergillosis and soft rot are the primary diseases of postharvest peach fruit. Our study aimed to investigate the biocontrol effect of Wickerhamomyces anomalus on the primary postharvest diseases of peach fruit and to explore its underlying physiological mechanism. The findings demonstrated that W. anomalus had an obvious inhibitory effect on Monilinia fructicola, Aspergillus niger and Rhizopus stolonifer. At the same time, W. anomalus can grow stably on the wound and surface of peach fruit at 25 °C and 4 °C and can form biofilm. W. anomalus increased the activity of resistance-related enzymes such as PPO, POD, GLU and the content of secondary metabolites such as total phenols, flavonoids and lignin in peach. Furthermore, the application of W. anomalus led to a reduced MDA level in peach fruit and increased activity of the active oxygen-scavenging enzyme system. This increase involved various antioxidant defense enzymes such as SOD and CAT, as well as ascorbic acid-glutathione (AsA-GSH) enzymes, including APX, GPX, GR, DHAR, and MDHAR. Our findings demonstrate that W. anomalus exerts its biocontrol effect by growing rapidly, competing with pathogens for nutrition and space, and enhancing the disease resistance and antioxidative capabilities of the peach fruit.

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The use of fungicides in the postharvest treatment of mangoes has been widespread due to the incidence of pathogens, but awareness of the health risks arising from their use has increased, driving the search for more sustainable treatments. This study aimed to evaluate the activity of antifungal treatment of seven essential oils (EO) against four fungi that cause postharvest diseases in mangoes and define the minimum inhibitory concentration (MIC) and chemical composition, analyzed by gas chromatography (GC-MS). The results showed that the EOs of oregano, rosemary pepper, cinnamon bark, and clove inhibited 100% of the mycelial growth of the studied pathogens, with MIC ranging from 250 to 2000 µL.L-1. The main compound found in oregano was carvacrol (69.1%); in rosemary and pepper oil, it was thymol (77.2%); cinnamaldehyde (85.1%) was the main constituent of cinnamon bark, and the eugenol (84.84%) in cloves. When evaluating the antifungal activity of these compounds, thymol and carvacrol showed greater inhibitory activity against fungi. Therefore, this study showed the great potential of oregano, clove, rosemary pepper, and cinnamon bark essential oil as alternative treatments to synthetic fungicides in controlling postharvest diseases in mangoes.

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Fungal diseases pose significant threats to the production of asparagus, resulting in economic losses and decreased crop quality. The potential of the yeast Yarrowia lipolytica as a biocontrol agent against Fusarium proliferatum, a common pathogen of asparagus, was investigated in this study. The effects of Y. lipolytica treatment on decay incidence, disease index, and activities of major disease defense-related enzymes were investigated. In addition, we examined the levels of antifungal compounds such as total phenols, flavonoids, and lignin in asparagus plants exposed to Y. lipolytica. The results showed that Y. lipolytica treatment significantly reduced decay incidence and disease index caused by F. proliferatum when compared to the control group. Furthermore, Y. lipolytica-treated plants showed increased activity of disease defense-related enzymes, indicating that defense responses were activated. The activities of all evaluated enzymes were significantly higher in Y. lipolytica-treated asparagus, indicating an improved ability to combat fungal pathogens. Furthermore, Y. lipolytica treatment increased the content of antifungal compounds such as total phenols, flavonoids, and lignin, which are known to possess antimicrobial properties. These findings highlight the potential of Y. lipolytica as a biocontrol agent for fungal diseases in asparagus crops. The ability of Y. lipolytica to reduce disease incidence, boost disease defense-related enzymes, and increase antifungal compound content provides valuable insights into its efficacy as a natural and sustainable approach to disease management. However, further investigations are needed to optimize application methods and determine its efficacy under field conditions.

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Postharvest diseases lead to substantial economic losses to the pear industry (Xu et al. 2021). In August 2022 and 2023, 'Housui' pears (Pyrus pyrifolia) with no visible wounds were harvested from Baoying county, Jiangsu Province, China and stored at 20°C with 85% relative humidity. Approximately 8% of pear fruits showed soft rot after 15 days of storage. The margin area of rot tissue was aseptically incubated on PDA medium at 25°C. Mycelial tips were transferred to new PDA after 24 h. Five fungal isolates were obtained after isolation and identification, including Alternaria sp., Botryosphaeria sp., Diaporthe sp., Fusarium sp. and Gilbertella sp. For each isolate, pathogenicity tests were confirmed three times by placing 10 µL of spore suspension (106 spores/mL) on three 'Housui' pear fruits superficially wounded with sterile toothpicks, and sterile distilled water served as controls. Lesions caused by Gilbertella sp. were distinctly observed after incubating at 20°C for 24h, and controls have no symptom. The lesions expanded to large brown spots with smelling of alcohol after 48 h, similar to natural disease symptom. The colony of Gilbertella sp. was initially white and rapidly turned gray, generating large amounts of black sporangia. -Sporangia were firstly white, then turn black, globose to dorsoventrally flattened, 70.22 to 131.58 × 75 to 135.17 µm, average 93.19 × 106.54 µm (n = 50), borne erect or nodding, breaking into two equal pieces. Sporangiophores were hyaline, 11.17 to 34.57 µm wide, average 19.67 µm (n = 50). Columellae were hyaline, pyriform or obovoid to cylindrical, with a distinct basal collar, 32.37 to 102.84 × 23.62 to 68.68 µm, average 60.06 × 40.07 µm (n = 50). Sporangiospores were single celled, mostly ellipsoid, 5.76 to 11.49 × 3.89 to 6.18 µm, average 8.68 × 5.08 µm (n = 100), attaching with 4-5 hyaline appendages at the ends. Chlamydospores were solitary or in short chain, cylindrical or oval. Zygospore was not observed. The isolate was morphologically identified as G. persicaria (Benny 1991). Molecular identification was performed by PCR amplification, sequencing and phylogenetic analysis of the internal transcribed spacer region of rDNA (ITS), partial 28S rDNA large subunit (LSU), and actin-1 (ACT-1) gene using primer pairs ITS1/ITS4, LR0R/LR5 and Gil_ACT_F/Gil_ACT_R (Zhang et al. 2020). The ITS (OP897009), LSU (OR794326), and ACT-1 (OR805109) sequences revealed 99.85%, 99.30% and 100% sequence identity to nucleotide sequences of G. persicaria from NCBI (ON875318, OP243274, and AJ287159). Phylogenetic analysis based on the maximum likelihood method grouped the isolate with other G. persicaria strains. Pathogenicity of the isolate was performed on wounded and non-wounded fruits. Wounded fruits severely rot after 48 h, and no non-wounded fruit rot after 5 days. Therefore, wound was required for the infection of G. persicaria. The pathogen was consistently re-isolated and purified from the inoculated pears, morphologically identified as G. persicaria, fulfilling Koch's postulates. Fruit rot caused by G. persicaria has been reported on peach, tomato, apricot, plum, apple, dragon fruit, papaya and eggplant, as well as Pyrus communis (Mehrotra 1964; Ginting et al. 1996; Cruz-Lachica et al. 2021). This is the first report of G. persicaria infection on 'Housui' pears in China. This disease is a potential threat to 'Housui' pear storage. The confirmation of this soft rot pathogen provides a foundation for pear postharvest disease prevention.

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Ceratocystis paradoxa is a major cause of postharvest disease in tender coconuts worldwide. We conducted a comprehensive study using widely targeted metabolomics, electronic tongue (E-tongue), and electronic nose (E-nose) analyses to investigate the impacts of C. paradoxa invasion on the quality of tender coconut water (TCW) from fresh control (FC), uninoculated (UN), skin-inoculated (SI), and deep-inoculated (DI) nuts. DI exhibited significantly higher taste indicators associated with bitterness, saltiness, astringency aftertaste, and bitter aftertaste, as well as odor sensor values related to various compounds such as long-chain alkanes, hydrides, methane, organic sulfides, etc. Invasion of C. paradoxa into the endosperm altered the flavor characteristics of TCW mainly through the modulation of carbohydrate and secondary metabolite pathways. Furthermore, significant correlations were observed between the differentially expressed flavorful metabolites and the sensor indicators of the E-nose and E-tongue. These findings offer valuable insights into understanding the impact of C. paradoxa infection on coconuts.

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Postharvest fruit rot caused by pathogens is a serious problem in the pear industry. This study investigated the fungal diversity and main pathogens and identified a new pathogen in the stored 'Huangguan' pear (Pyrus bretschneideri Rehd.), the dominant pear variety in northern China. We sampled 20 refrigeration houses from five main producing regions in Hebei Province and used Illumina sequencing technology to detect the fungal composition. Alternaria (56.3%) was the most abundant fungus, followed by Penicillium (9.2%) and Monilinia (6.2%). We also isolated and identified nine strains of Alternaria and four strains of Penicillium. Moreover, we observed a new postharvest fruit disease in 'Huangguan' pear caused by Stemphylium eturmiunum, which was confirmed by phylogenetic analysis by combining the sequences of three conserved genes, including internal transcribed spacer, gapdh, and calmodulin. This study marks the first documentation of S. eturmiunum causing fruit rot in 'Huangguan' pears, offering valuable insights for identifying and controlling this newly identified postharvest disease.

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The biocontrol effectiveness of Metschnikowia citriensis relies on its production of pulcherriminic acid (PA), which forms insoluble and stable pulcherrimin pigments by chelating iron ions, this inhibits pathogen growth by preventing their utilization of chelated Fe3+. In this study, ΔM. citriensis, which did not produce PA, was used as a control to examine changes in its biocontrol effectiveness by adding tryptophan to the medium. Tryptophan was shown to have no discernible impact on the growth and PA production of ΔM. citriensis; moreover, the PA synthesis-related genes PULs, Snf2, and leucyl-tRNA synthesis-related genes A3136 and A3022 were all down-regulated in ΔM. citriensis. The PA-free ΔM. citriensis eventually showed a much poorer inhibition zone against the pathogens in vitro, and a noticeably decreased control efficiency against postharvest diseases in citrus fruit. Tryptophan was added to the medium, which had no appreciable impact on inhibitory zone of ΔM. citriensis against pathogens in vitro, but enhanced its ability to control citrus postharvest diseases. Additionally, the control effects of culture broth of M. citriensis and ΔM. citriensis on postharvest diseases in citrus fruit were assessed. It was found that both culture broth of M. citriensis and ΔM. citriensis exhibited remarkable control effects against citrus postharvest diseases, with culture broth of M. citriensis which containing PA being more effective in controlling the disease. Last but not least, we extracted and dissolved pulcherrimin to obtain PA extracts, which were then injected to citrus fruits to assess the biocontrol effectiveness. The findings demonstrated that postharvest diseases of citrus fruit can be effectively controlled by PA extracts. This research suggested a new biological strategy for the management of citrus postharvest diseases.

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Blue mold (penicilliosis) is a common disease of Lanzhou lily (Lilium davidii var. willmottiae) during postharvest storage, which not only seriously affects the appearance and reduces the quality of lily bulbs, but also leads to the accumulation of mycotoxins in rotten lily tissues, seriously endangering human health. Therefore, it is of great significance to clarify the main isolates causing postharvest blue mold of fresh Lanzhou lily and put forward effective measures to control the disease caused by these pathogens. In this study, pathogens were isolated and purified from the naturally diseased blue-mold tissue of Lanzhou lily, and then morphological and molecular biology techniques were applied to identify the isolates, verify the pathogenicity, determine the disease index and disease incidence, and finally, to analyze the control effect of ozone treatment on the blue mold of lily scale and mycotoxin accumulation. The results indicated that the main isolates causing postharvest blue mold of lily were Talaromyces adpressus, Penicillium gladioli, T. calidominioluteus, and P. polonicum. The pathogenicity test showed that P. gladioli and P. polonicum had a higher disease index than T. calidominioluteus and T. adpressus. Ozone treatment significantly reduced the incidence of disease caused by P. gladioli and P. polonicum, and effectively controlled the accumulation of patulin. This study characterized the main pathogens causing blue mold of postharvest Lanzhou lily during storage, and confirmed ozone application has a significant inhibitory effect on blue mold development and patulin accumulation in Lanzhou lily, which could be helpful in commercially controlling blue mold of postharvest Lanzhou lily during storage.

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Postharvest diseases caused by fungal pathogens are significant contributors to the postharvest losses of fruits. Moreover, some fungal pathogens produce mycotoxins, which further compromise the safety and quality of fruits. In this review, the potential of biotechnological and biocontrol approaches for mitigating postharvest diseases and mycotoxins in fruits is explored. The review begins by discussing the impact of postharvest diseases on fruit quality and postharvest losses. Next, it provides an overview of major postharvest diseases caused by fungal pathogens. Subsequently, it delves into the role of biotechnological approaches in controlling these diseases. The review also explored the application of biocontrol agents, such as antagonistic yeasts, bacteria, and fungi, which can suppress pathogen growth. Furthermore, future trends and challenges in these two approaches are discussed in detail. Overall, this review can provide insights into promising biotechnological and biocontrol strategies for managing postharvest diseases and mycotoxins in fruits.

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The postharvest disease popularly known as gray mold is considered one of the most limiting factors strawberry fruit production. The most effective way to control this disease is still the use of chemical fungicides. However, other alternative sources of control are being explored. Among these, psychrophilic yeasts adapted to extreme conditions, such as those found in the Antarctic region, may have great potential for use as biocontrol agents. Thus, the present study aimed to select psychrotolerant yeasts obtained from Antarctic region and to evaluate their potential for biocontrol under gray mold, caused by Botrytis cinerea in strawberries stored at low temperature. For this, 20 potential antagonist yeasts were evaluated in vitro (thermotolerance and enzymatic) assays. Debaryomyces hansenii, Rhodotorula mucilaginosa and Dioszegia hungarica were selected for growing in strawberry juice. However, only D. hansenii was selected for in vivo studies and showed a reduction in the incidence of gray mold by 82% for the tests performed on injury and 86% for the tests on non-injured fruits treated by immersion bath. Thus, demonstrating that the selection of this cold-adapted Antarctic yeast can be a promising strategy as a biocontrol agent used to curb the development of gray mold in strawberry fruits.

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Banana is a fruit of great importance in Brazil and crown rot cause considerable damage and losses (Ploetz et al. 2003). The disease is associated with fungal complexes, especially the Lasiodiplodia theobromae sensu lato (Kamel et al. 2016; Renganathan et al. 2020; Waliullah et al. 2022). Three asymptomatic bunches of banana cv. 'Prata Catarina' were collected in Russas, Brazil (04°58'11.6"S, 38°01'44.5"W), in 2017. The samples were disinfected (NaClO, 200 ppm), and incubated in a moist chamber at 28 °C, with 12 h light/12 h dark for 3 days. With the appearance of the symptoms (32% of severity), the isolation was conducted in potato dextrose agar (PDA). A monosporic culture (BAN14) was obtained from a typical crown rot lesion, which was subjected to morphological characterization, showing abundant aerial mycelium of olivaceous grey color on the surface and greenish grey on the back (Rayner 1970) in PDA after 15 days at 28 °C. The growth rate was 28.2 mm. day-1. The fungus produced pycnidia and conidia on water agar medium containing pine needles, with 3-4 weeks at 28 °C, presenting conidia initially aseptate, subglobose to subcylindrical, becoming pigmented with 1-central transverse septum and longitudinal striations 23.5 (18.7) 26.0 x 12.7 (9.7) 14.8 µm (n=50). Paraphyses, hyaline, cylindrical, thin-walled, apparently coenocytic with rounded apex, with length and width dimensions of 34 (43.8) 53.2 x 2.1 (2.5) 3.2 µm (n=30). Conidiophore absent, conidiogenous cells hyaline, smooth and with thin walls. The genomic DNA was extracted and amplified by PCR with primers TEF1-688F/TEF1-1251R, ITS1/ITS4, and Bt2a/Bt2b, and sequenced in both directions (O'Donnell et al. 1998; O'Donnell et al. 2010) (GenBank accession ON975017 [TEF1], ON986403 [TUB2], and ON921398 [ITS]). BLASTn analysis of TEF1, TUB2 and ITS sequences in NCBI database showed 99 to 100% nucleotide identity to a representative isolate of Lasiodiplodia iraniensis (IRAN921). Phylogenetic analysis using maximum parsimony based on the combined TEF1, TUB2 and ITS sequences indicated that the BAN14 formed a supported clade (82% bootstrap value) to L. iraniensis. The pathogenicity was evaluated in 20 banana fruit cv. 'Prata Catarina', at the point of harvest. For inoculation, the bananas were washed with water and soap, and disinfected with NaClO (200 ppm). Posteriorly, two wounds were made on the extremities of the fruits, in which were deposited mycelial discs of 5 mm in diameter, with 7 days of the growth on PDA. After inoculation, the fruits were incubated in plastic boxes in a wet chamber at 25 °C, with 12 h light/12 h dark for 5 days. The control fruits were not inoculated with the pathogen, only with PDA discs. The experiments were repeat twice. The BAN14 isolate was pathogenic to the banana cv. 'Prata Catarina'. The BAN14 was grouped with the species L. iraniensis described by Abdollahzadeh et al. (2010) in Iran. This species is distributed in Asia, South and North America, Australia, and Africa. In Brazil it was reported in association to Anacardium occidentale, Annona muricata, A. squamosa, Annona ×cherimola-squamosa, Citrus sp., Eucalyptus sp., Jatropha curcas, Mangifera indica, Manihot esculenta, Nopalea cochenillifera, Vitis sp. and V. vinifera. Until the moment, there is not description of the relation between banana crown rot and L. iraniensis (Farr and Rossman 2022). Our work is the first report on the pathogenicity of this species on banana fruit cv. 'Prata Catarina' worldwide.

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The use of synthetic fungicides against postharvest Alternaria rot adversely affects human health and the environment. In this study, as a safe alternative to fungicides, Bacillus subtilis strain Y17B isolated from soil exhibited significant antifungal activity against Alternaria alternata. Y17B was identified as B. subtilis based on phenotypic identification and 16S rRNA sequence analysis. To reveal the antimicrobial activity of this strain, a PCR-based study detected the presence of antifungal lipopeptide (LP) biosynthetic genes from genomic DNA. UPLC Q TOF mass spectrometry analysis detected the LPs surfactin (m/z 994.64, 1022.68, and 1026.62), iturin (m/z 1043.56), and fengycin (m/z 1491.85) in the extracted LP crude of B. subtilis Y17B. In vitro antagonistic study demonstrated the efficiency of LPs in inhibiting A. alternata growth. Microscopy (SEM and TEM) studies showed the alteration of the morphology of A. alternata in the interaction with LPs. In vivo test results revealed the efficiency of LPs in reducing the growth of the A. alternata pathogen. The overall results highlight the biocontrol potential of LPs produced by B. subtilis Y17B as an effective biological control agent against A. alternata fruit rot of cherry.

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Fungal response to oxidative stress during infection on postharvest fruit is largely unknown. Here, we found that hydrogen peroxide (H2O2) treatment inhibited the growth of Fusarium proliferatum causing crown rot of banana fruit, confirmed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observation. H2O2 exposure increased endogenous reactive oxygen species (ROS) and fumonisin B1 (FB1) production in F. proliferatum, possibly by modulating FUM or ROS-related gene expression. Importantly, H2O2 treatment inhibited F. proliferatum growth in vivo but induced FB1 accumulation in banana peel. Finally, we constructed the FpFUM21 deletion mutant (ΔFpfum21) of F. proliferatum that was attenuated in FB1 biosynthesis and less tolerant to oxidative stress. Moreover, the ΔFpfum21 strain was less virulent compared to the wild type (WT) due to the inability to induce FB1 production in the banana host. These results suggested that FB1 biosynthesis is associated with oxidative stress in F. proliferatum and contributes to fungal infection on banana fruit.

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