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The danger of mycotoxin contamination entering the food supply through post-harvest infection is of perennial concern to food safety experts. To explore the distribution of Penicillium expansum and diffusion of its mycotoxin, patulin, in blue mold-damaged pears, Pyrus bretschneideri Rehd. cv. Yali obtained from markets and orchards in China were artificially inoculated with P. expansum and assayed for patulin accumulation and degree of fungal colonization. The inoculated pears were incubated until the lesions were 5, 10, 20, or 30 mm in diameter. We sampled tissue at a range of distances from the lesion, measured the spread of Penicillium by plate colony-counting methods, and used UHPLC-MS/MS to detect and quantify the patulin concentration. More P. expansum colony-forming units were isolated from pears with a higher degree of decay. Farther from the lesion, the fewer P. expansum colonies were observed, and the lower the patulin content detected. We found a significant difference in the patulin content between samples due to lesion size, and also in tissue sampled 10 mm away from the lesion. In consideration of this finding, to ensure food safety, we recommend that when a blue mold rot lesion on pear is 5, 10, or 20 mm in diameter, 20, 30, and 40 mm beyond the lesion should be removed, respectively. If a lesion surpasses 30 mm in diameter, the whole pear should be thrown away.

In this study, the role of WSC1 in the infection of pear fruit by Penicillium expansum was investigated. The WSC1 gene was knocked out and complemented by Agrobacterium -mediated homologous recombination technology. Then, the changes in growth, development, and pathogenic processes of the knockout mutant and the complement mutant were analyzed. The results indicated that deletion of WSC1 slowed the growth rate, reduced the mycelial and spore yield, and reduced the ability to produce toxins and pathogenicity of P. expansum in pear fruits. At the same time, the deletion of WSC1 reduced the tolerance of P. expansum to cell wall stress factors, enhanced antioxidant capacity, decreased hypertonic sensitivity, decreased salt stress resistance, and was more sensitive to most metal ions. Our results confirmed that WSC1 plays an important role in maintaining cell wall integrity and responding to stress, toxin production, and the pathogenicity of P. expansum .

Patulin is a secondary metabolite produced primarily by the fungus Penicillium expansum, responsible for the blue mold disease on apples. It is found in apple products including apple cider when apple juice is added after fermentation. In the present study, two hundred and twenty-five cider-apples of the variety “Bedan”, cultivated in Brittany in France, were sampled from the orchard during harvesting until the storage step, right before processing. The patulin analysis on these samples reported a low contamination at the orchard and a significantly higher-level of contamination in the cider-apples starting from the transporting bin. The percentage of positive samples increased from 6% to 47% after 12 h in the harvesting bin before transporting and reached 95% after 24 h of transporting, decreasing then to 69% at the end of the storage. Penicillium expansum was quantified on the surface of apples using real-time PCR and was observed to be mostly consistent between the harvest and post-harvest steps. It was detected on average, on the surface of 85% of all sampled apples with a mean value around 2.35 × 106Penicillium expansum DNA/g of apple. Moreover, the changes in the fungal and bacterial epiphytic microbiota in the different steps were studied using a metabarcoding approach. The alpha and beta diversity analysis revealed the presence of unique and more diverse bacterial and fungal communities on the surface of apples picked from the orchard compared to the rest of the sampling steps. Potential indigenous biological control agents were identified on the surface of sampled apples. Future perspective includes developing actions of prevention and control of the contamination by Penicillium expansum during the harvest and along the various critical post-harvest stages before transformation in a sustainable development concern.

Postharvest food decay is one major issue for today's food loss along the supply chain. Hot water treatment (HWT), a sustainable method to reduce pathogen-induced postharvest fruit decay, has been proven to be effective on a variety of crops. However, the microbiome response to HWT is still unknown, and the role of postharvest microbiota for fruit quality is largely unexplored. To study both, we applied a combined approach of metabarcoding analysis and real time qPCR for microbiome tracking. Overall, HWT was highly effective in reducing rot symptoms on apples under commercial conditions, and induced only slight changes to the fungal microbiota, and insignificantly affected the bacterial community. Pathogen infection, however, significantly decreased the bacterial and fungal diversity, and especially rare taxa were almost eradicated in diseased apples. Here, about 90% of the total fungal community was composed by co-occurring storage pathogens Neofabraea alba and Penicillium expansum. Additionally, the prokaryote to eukaryote ratio, almost balanced in apples before storage, was shifted to 0.6% bacteria and 99.4% fungi in diseased apples, albeit the total bacterial abundance was stable across all samples. Healthy stored apples shared 18 bacterial and 4 fungal taxa that were not found in diseased apples; therefore, defining a health-related postharvest microbiome. In addition, applying a combined approach of HWT and a biological control consortium consisting of Pantoea vagans 14E4, Bacillus amyloliquefaciens 14C9 and Pseudomonas paralactis 6F3, were proven to be efficient in reducing both postharvest pathogens. Our results provide first insights into the microbiome response to HWT, and suggest a combined treatment with biological control agents. [ABSTRACT FROM AUTHOR]

1-Octen-3-ol is one of the most abundant volatile compounds associated with fungi and functions as a germination and growth inhibitor in several species. By investigating its effect on the biosynthesis of patulin, a mycotoxin made by Penicillium expansum, it was found that a sub-inhibitory level of volatile 1-octen-3-ol increased accumulation of patulin on a medium that normally suppresses the mycotoxin. Transcriptomic sequencing and comparisons of control and treated P. expansum grown on potato dextrose agar (PDA; patulin permissive) or secondary medium agar (SMA; patulin suppressive) revealed that the expression of gox2, a gene encoding a glucose oxidase, was significantly affected, decreasing 10-fold on PDA and increasing 85-fold on SMA. Thirty other genes, mostly involved in transmembrane transport, oxidation-reduction, and carbohydrate metabolism were also differently expressed on the two media. Transcription factors previously found to be involved in regulation of patulin biosynthesis were not significantly affected despite 1-octen-3-ol increasing patulin production on SMA. Further study is needed to determine the relationship between the upregulation of patulin biosynthesis genes and gox2 on SMA, and to identify the molecular mechanism by which 1-octen-3-ol induced this effect. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• (1→3)-β-D-glucan was characterized by monosaccharide composition, FTIR and NMR. • (1→3)-β-D-glucan remarkably induced resistance to blue mold rot in pear fruit. • (1→3)-β-D-glucan inhibited the growth of pathogen after 24 h of treatment in pear. • The defense mechanism might be associated with the activation of PR proteins. In this study, the (1→3)-β-D-glucan was isolated from yeast cell wall for investigating its effect on reducing the postharvest decay of pear fruit caused by Penicillium expansum and the underlying mechanisms. The results demonstrated that (1→3)-β-D-glucan could significantly induce disease resistance against P. expansum in pear wounds. (1→3)-β-D-glucan did not directly affect the growth of P. expansum in vitro and in vivo , whereas the spore germination of the pathogen was obviously inhibited in pear wounds when the induction time increased to 24 h by (1→3)-β-D-glucan. Furthermore, a large variety of defense-related genes, including PR1 , GLU , endoGLU9 , CHI4 , endoCHI , PR4 , PR5 , CHI3 and PAL , were markedly up-regulated by (1→3)-β-D-glucan treatment. To the best of our knowledge, this is the first report that (1→3)-β-D-glucan can induce the disease resistance in the postharvest fruit. These findings suggest that application of (1→3)-β-D-glucan may be an effective strategy to reduce the fungal rot of the postharvest fruit. [ABSTRACT FROM AUTHOR]

• For the first time, the feasibility of application of Baobab extracts as BCAs. has been reported. • Baobab extract enhances biocontrol efficacy of Sporidiobolus pararoseus Y16. • Baobab extract improves population dynamics of antagonist both in wounds and surface. The utilization of natural compounds to preserve fruit quality and extend the shelf life has gained great interest worldwide. African Baobab (AB) fruit (Adansonia digitata L.) produces some of these natural compounds, which contain several bioactive antioxidants with ascorbic acid being the major component. Sporidiobolus pararoseus Y16 combined with African Baobab extract (100 mg/ml) significantly inhibited the growth of Penicillium expansum infection than either yeast or African Baobab alone during storage at either 4 °C for 30 days followed by 20 °C for 15 days or 20 °C for 30 days. Furthermore, the apple treated with Sporidiobolus pararoseus Y16 and African Baobab significantly (P < 0.05) reduced the decay incidence and lesion diameter (in vivo), and colony diameter (in vitro) compared to the control. Moreover, fruits preserved with either Sporidiobolus pararoseus Y16 or African Baobab alone or their combination indicated no significant influence on the quality parameters of apple. The results of this study demonstrated a promising approach to enhancing the biocontrol performance of antagonistic yeast by employing African Baobab, and it has potential to help commercial producers and retailers in prolonging the shelf life of agricultural produce over a wider range in the future. [ABSTRACT FROM AUTHOR]

Highlights • Hongyang kiwifruit is more resistant to blue mold than Qihong kiwifruit. • Hongyang kiwifruit showed a higher biochemical resistance than Qihong kiwifruit. • The outer epidermal structure of Hongyang kiwifruit has disease resistance characteristics. Abstract This study aimed to reveal the physiological mechanism of resistance to postharvest blue mold of kiwifruit. Hongyang and Qihong kiwifruits were inoculated with Penicillium expansum (P. expansum) and stored at low temperature (0 ± 1 °C). The disease incidence and lesion diameter, activities of defense-related enzymes, and contents of defense-related substance of Hongyang and Qihong kiwifruits were also compared, combined with the observation of fruit pericarp structure by scanning electron microscopy. Results showed that the disease resistance of Hongyang was stronger than that of Qihong with late onset, low incidence, and small lesion diameter. And Hongyang kiwifruit showed a high biochemical resistance after inoculation with P. expansum. The epidermis structure of Hongyang kiwifruit had typical disease resistance characteristics with a dense epidermis structure, orderly cell arrangement, and less obvious microcracks. The strong biochemical resistance, dense, and complete epidermis structure of Hongyang fundamentally guarantee its strong resistance to diseases. [ABSTRACT FROM AUTHOR]

Mycotoxins are the secondary metabolites secreted by different types of fungi to which humans can get exposed mainly via ingestion. Patulin (C 7 H 6 O 4) is a polyketide lactone produced by various fungal specifies, including Penicillium expansum as the main producer. P. expansum can infect different fruits and vegetables yet it has preference to apples in which they cause blue rot. Therefore, apples and apple-based food products are the main source of Patulin exposure for humans. Patulin was first identified in 1943 under the name of tercinin as a possible antimicrobial agent. Although it is categorized as a non-carcinogen, Patulin has been linked, in the last decades, to neurological, gastrointestinal, and immunological adverse effects, mainly causing liver and kidney damages. In this review, the characteristics of and possible human exposure pathways to Patulin are discussed. Various surveillance and toxicity studies on the levels of Patulin in various food products and effects of Patulin on cells and animal models have been documented as well. Importance of epidemiological studies and a summary of the possible toxicity mechanisms are highlighted with a case study. The commonly used control methods as described in the literature are also discussed to guide future researchers to focus on mitigating mycotoxins contamination in the food industry. [ABSTRACT FROM AUTHOR]

Postharvest disease of pears caused by pathogens results in great economic losses. The aim of this research was to isolate a strain of potential antagonistic yeast from soil of orchards, and to test the control efficacy against postharvest blue mold decay of pears. By molecular biological identification based on comparative sequence analysis of 5.8S rDNA gene, the antagonistic strain was identified as Wickerhamomyces anomalus. The results showed that W. anomalus significantly reduced the disease incidence and lesion diameter of blue mold of pears compared with the control in vivo. The disease incidence caused by Penicillium expansum of pears was only 5.56%, when treated with 1 × 108 cells/mL W. anomalus , compared with 100% disease incidence of the control. In vitro test showed that W. anomalus reduced the spore germination rate and germ tube length of P. expansum. Meanwhile, polyphenoloxidase (PPO), peroxidase (POD), catalase (CAT) and chitinase (CHI) activities of the pears treated by W. anomalus were significantly higher than that of the control. And the expression levels of defense-related enzymes were significantly induced by W. anomalus. All these results indicated that W. anomalus has the potential to control postharvest diseases of pears, and the mechanisms involved in inhibiting spore germination and germ tube length, induction of the activities of the defense-related enzymes of pears, and improvement of the expression levels of defense-related genes of pears. [ABSTRACT FROM AUTHOR]

Copyright of China Brewing is the property of China Brewing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Penicillium expansum is a cosmopolitan pathogen that can cause several damages to fruit crops, leading to an intense search for alternative methods for its control. This study aimed to assess the antimicrobial effects of Cymbopogon martinii , Illicium verum and Melaleuca alternifolia essential oils (EOs) against P. expansum , elucidating their mechanisms of action. The P. expansum conidia were exposed to the vapor phase of the EOs, in different concentrations (0.125 g L−1 to 1 g L−1), for different times (1–24 h). Their fungicidal/fungistatic effects assessed in vitro , and their mechanisms of action investigated through DNA, protein and glucose extravasation, lipid damage, reactive oxygen species accumulation and antioxidant activity. In situ , their antimicrobial activities were assessed on apples cv. Fuji. The EOs inhibited 100% of fungal germination after 4 h at 0.25 g L−1, causing damages to the plasma membrane, leading to DNA (∼69.27 ng), protein (∼39.28 μg) and glucose (∼5.77 mg) leakage, and lipid damage (∼7.72 pmol of TBARS). Although a high efficiency to inhibit P. expansum through an antioxidant activity was observed, a minor effect was observed in situ , indicating different interactions between EOs and the environment, which can reduce their antimicrobial activities. Highlights • The vapor phase of palmarosa, star anise and tea tree essential oils (EOs) have fungicidal activity against P. expansum. • The antimicrobial activity of the EOs are not related to the cell wall of P. expansum conidia. • The EOs were able to cause damaged to the plasma membrane of P. expansum conidia. • The packaging material used can affect the in situ activity of the EOs. [ABSTRACT FROM AUTHOR]

Penicillium expansum -infected apple fruit resulted in a disrupted balance of primary metabolites and impacted the ascorbate–glutathione cycle. The initial decline in fructose, malic acid, shikimic acid and total ascorbate content (6 hpi) was followed by a significant increase in malic acid (24 hpi) and total glutathione (3 dpi). Significant increase in sucrose was accompanied by a decline in glucose and ascorbate content (5 dpi). Total glutathione and shikimic acid gradually deteriorated with symptom development. A negative correlation was found between sucrose and ascorbate-glutathione pool. Other correlations were strong amongst other metabolites and lesion size indicating that they may be involved or important for apple fruit decay. • Decline of primary metabolites occurs to provide energy for antioxidative defence response. • Total GSH significantly increases 3 dpi reflecting an intensification of antioxidative defense. • Lesion size is with fructose and AA in positive and with organic acids and total GSH in negative correlation. • GSH and shikimic acid significantly deteriorated at advanced stages of infection. • Changes in P. expansum infected apples correspond to the general ecophysiological stress–response concept. [ABSTRACT FROM AUTHOR]

Highlights • P. expansum accelerated ripening and changed VOCs release of apple fruit. • Three common special VOCs were detected in infected fruits of two cultivars. • 'Delicious' was susceptible to P. expansum than 'Fuji'. Abstract Blue mold caused by Penicillium expansum is a major postharvest disease of apple fruit, which leads to fruit loss and patulin accumulation. In this study, 'Delicious' and 'Fuji' apples were inoculated with P. expansum to investigate effects of infection on physiology, quality and release of volatile compounds. The results showed that P. expansum significantly promoted ethylene production, increased respiration rate, and induced higher peaks of ethylene and respiration in fruit. The fungus also caused a lower of membrane integrity, firmness, and the content of total soluble solid and titratable acid. Moreover, P. expansum increased the content of volatile compounds in two cultivars of apple. C6 alcohol and aldehyde contents were significantly improved by inoculation in the earlier storage stage, and ester contents were improved in the middle and later storage stage. According to PLS-DA analysis, hexanoic acid and hexanal were the most important factors to distinguish the inoculated 'Delicious' and 'Fuji' from their controls. Interestingly, among specific volatile compounds detected in the two inoculated cultivars, 3 volatile compounds, including phenethyl acetate, methyl 2-methylbutanoate and ethyl benzeneacetate, were common in both of inoculated fruit. Although wounding increased ethylene production and respiration rate, decreased quality of the two cultivars and affected volatiles release, the effects were less than P. expansum. Compared with 'Fuji', the inoculated 'Delicious' had a higher of lesion diameter, ethylene production and respiration rate and content of total soluble solid, and a lower of membrane integrity, firmness and content of titratable acid. The inoculated 'Delicious' also released more volatile compounds, especially C6 volatiles. In general, P. expansum inoculation promoted ripening and quality loss, leading to change of volatile compounds during storage and release of specific volatiles. Moreover, 'Delicious' was more susceptible to P. expansum than 'Fuji'. [ABSTRACT FROM AUTHOR]

BACKGROUND: Patulin, produced by Penicillium expansum in apple fruit, has side effects affecting human and animal health. The effect of chlorine dioxide (ClO2) on patulin production, and the mechanisms involved in this, were investigated. RESULTS: Patulin production by P. expansum was reduced by ClO2 treatment, both in apples and in a potato dextrose broth (PDB) medium, which was attributed to the antifungal effect of ClO2, but not the direct reaction between ClO2 and patulin. Fumigation with ClO2 also significantly reduced disease development in apples infected with P. expansum, and inhibited mycelial growth and spore germination. After ClO2 treatment, P. expansum mycelial morphology was strongly affected, leading to the loss of plasma membrane integrity and causing cellular leakage. CONCLUSION: These data provide useful information that enables the inhibitory mechanism of ClO2 on patulin production by P. expansum to be better understood. It can also assist the development of effective methods to control patulin production in apples and other postharvest fruits. © 2018 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Highlights • The secretome of the blue mold pathogen, Penicillium expansum was analyzed. • Pipeline for prediction of pathogenicity-related factors was constructed and applied. • Subtilisin-related peptidase was found among putative genes involved in pathogenicity. • Deletion of Peprt resulted in reduced virulence of P. expansum. Abstract Blue mold caused by Penicillium expansum is a major postharvest disease of pome fruit. Several mechanisms possibly involved in P. expansum pathogenicity and virulence. However, factors that mediate pathogenicity and virulence are largely not yet characterized. In this work we analyzed P. expansum predicted secretome to reveal potential genes that have a role in host-pathogen interaction. A prediction pipeline was designed using an approach that combines common effector features, transcriptomic data and homology to proteins reported to be involved in pathogenicity of other pytopathogenic fungi. Among 297 genes predicted in P. expansum secretome, 103 genes (35%) were found to code for hydrolytic enzymes. The majority of the secreted enzymes are carbohydrate-degrading enzymes among which five coding for pectin-degrading enzymes are highly induced during the infection and decay of apple fruit by P. expansum, indicating that they may represent an important aspect of pathogenicity and virulence. Applying the pipeline we have predicted 17 candidate genes coding for proteins that are most likely involved in pathogenicity and virulence. One of the top candidates is a subtilisin-related peptidase, S8 (PePRT), proteolytic enzyme highly expressed in planta , and potentially involved in authophagy process. Deletion of PePRT-coding gene resulted in reduced virulence of P. expansum on apples. Moreover, Δ Peprt exhibited decreased sporulation as well as affected mycelial morphology and internal mycelial cell structure. [ABSTRACT FROM AUTHOR]

The biocontrol potential of four wild yeast strains (Meyerozyma guilliermondii – strain YS-1, Meyerozyma caribbica – strain YS-3, Cryptococcus albidus – strain YS-4, and Cryptococcus sp. – strain YS-5) against Penicillium expansum was studied in vivo (on Golden Delicious apples). The test yeasts were applied to the fruits alone as well as in combination with 2% CaCl2. Treated apples were stored at room temperature (~21°C) for up to 2weeks or under refrigeration (3°C) for up to 2months. Candida oleophila was used as positive biocontrol agent. Biocontrol activities were expressed as percentages of lesion size reduction caused by the test yeasts or by test yeasts+CaCl2 as compared with decays on apples treated with P. expansum alone. All strains tested during this study showed some degree of biocontrol activity against P. expansum. When the test yeasts were applied alone, they effected moderate pathogen inhibition reducing the decay size by 28% to 52% at day 7 and 11% to 27% at day 14 of incubation at room temperature. When the treated apples were stored at 3°C, lesion size reduction was between 48% and 63% after 1month and 24% to 41% after 2months of incubation. Addition of CaCl2 to yeast suspensions facilitated much higher pathogen inhibition. At room temperature, lesion size reduction ranged between 74% and 77% during the first week. After 2weeks of incubation, decays on yeast+CaCl2-treated apples were still substantially smaller (49%-73% lower) than those on apples treated with P. expansum alone. At refrigeration, lesion size reduction ranged between 76% and 92% in the first month of storage and between 75% and 87% after 2months of incubation. Decay incidence was 75% to 100% in apples stored at room temperature and 30% to 85% in those kept under refrigeration. The inhibitory activities of the wild yeast strains were similar to those exhibited by C. oleophila for the most part. These strains, when combined with CaCl2, showed high potential as biocontrol agents against P. expansum on stored apples. [ABSTRACT FROM AUTHOR]

The aim of research was to study the mannan-degrading activity of isolated micromycete cultures. Methods. The identification of cultures was carried out on a complex of cultural and morphological characteristics. β-Mannanase activity was determined by the dinitrosalicylic method, synthetic nitrophenyl substrates were used to assay other glycosidase activities. Results. From the plant substrates and bodies of bees nine strains of micromycetes were isolated. As a result the identification of the culture was attributed to the species Rhizopus oryzae Went & Prins. Geerl. (3 strains), Penicillium cyclopium Westling (2 strains), Aspergillus sp. (1 strain), Penicillium expansum Lk (3 strains). For the first time β-mannanase and α-galactosidase activity have been demonstrated in representatives of the species R. oryzae, P. cyclopium, P. expansum. It was found that galactomannan guar (0.5%) provides high β-mannanase (1.5 - 8.5 U/ml) and α-galactosidase (1,1 - 2,4 U/ml) activity in the culture fluid of the micromycetes. The best sources of nitrogen for culture growth and enzyme synthesis were peptone, yeast autolysate and ammonium sulfate (at a concentration of 5.0, 1.0, and 1.0 g/l respectively). The maximum mannan-degrading activity of micromycetes was observed at 25 °C on the 5th day of cultivation. Conclusions. New strains with high β-mannanase and α-galactosidase activity were obtained, promising for use in biotechnological processes of degradation of plant raw materials with a high content of mannans. [ABSTRACT FROM AUTHOR]

Featured Application: The potential applications of the lactoperoxidase system are in human health and in plant pest control. However, practical applications of this natural preservative system are still limited due to various factors that can dramatically reduce its antimicrobial activity. For an industrial application, it is fundamental to understand factors affecting lactoperoxisase activity. This study is a contribution to the increased knowledge on this issue. Lactoperoxidase is an enzyme that generates oxidants with antimicrobial activity in presence of a (pseudo)halogen and hydrogen peroxide, but various factors can drastically reduce the antimicrobial activity of the lactoperoxidase system. Spectroscopic, ionic chromatography, and 13C-NMR methods showed that the oxidants generated by lactoperoxidase are OSCN− in the presence of SCN− and I2 in the presence of I−. Neither of them, however, inhibited Penicillium expansum, one of the causal agents of fruit mold. When a mixture of SCN− and I− was used, no OSCN−, OCN−, I2, or interhalogen I2SCN− was produced. However, its long-term stability, NH2-oxidizing capacity, and antifungal activity against P. expansum argue in favor of an I−-derived oxidant. Strongly mineralized water optimized enzyme-catalyzed reactions with higher oxidant production. Storage at 4 °C resulted in long-term stability and extended antifungal activity against P. expansum. The relative iodide/thiocyanate concentrations turned out to be important, as better in vitro inhibition of Botrytis cinerea, the causal agent of apples's grey mold, was obtained with a high KI + KSCN concentration, a KI/KSCN ratio of 4.5, and a (KI + KSCN)/H2O2 ratio of 1. The nature of the substrates, their relative concentrations, the medium, and the storage temperature modifed the antifungal activity of lactoperoxidase. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Summary: Amongst the universal diseases affecting apples, blue mould caused by Penicillium expansum is a major concern, resulting in yield and quality losses as a result of the production of the mycotoxin patulin. Despite the characterization of the patulin biosynthetic gene cluster at both the molecular and chemical levels, the underlying regulation of patulin biosynthesis in P. expansum and the mechanisms of apple colonization remain largely obscure. Recent work has indicated that sucrose, a carbon catabolite repressive metabolite, is a critical factor in the regulation of patulin synthesis. Here, CreA, the global carbon catabolite regulator, was assessed for virulence both in vitro and in vivo. We showed that loss‐of‐function creA strains were nearly avirulent and did not produce patulin in apples. On the basis of RNA‐sequencing (RNA‐seq) analysis and physiological experimentation, these mutants were unable to successfully colonize apples for a multitude of potential mechanisms including, on the pathogen side, a decreased ability to produce proteolytic enzymes and to acidify the environment and impaired carbon/nitrogen metabolism and, on the host side, an increase in the oxidative defence pathways. Our study defines CreA and its downstream signalling pathways as promising targets for the development of strategies to fight against the development and virulence of this post‐harvest pathogen. [ABSTRACT FROM AUTHOR]

Although the Sar/Arf GTPase belonging to a small family of GTPases contributes to growth of fungi, its function in postharvest fungi has not been characterized. Here, ArfA and SarA gene deletion mutants were generated in Penicillium expansum. We found that Δ ArfA and Δ SarA exhibited attenuated colony growth and rough colony morphology, as well as insufficient spore development. Δ ArfA also increased hyphal branches. Stress experiments showed that knocking out the ArfA or SarA genes affected cell wall integrity of the P. expansum strain. In addition, Δ ArfA and Δ SarA significantly downregulated the expression of genes controlling spore development (wetA, abaA and brlA) and MAPK pathway regulators (Fus3 , Kss1 , Hog1 and Mpk1). Absence of ArfA and SarA reduced patulin production, and the related gene expression was significantly limited. Δ ArfA showed attenuated virulence in infected fruit and downregulated PG and PL gene expression. However, Δ SarA had no significant effect on fungal virulence. Taken together, both ArfA and SarA contribute to the growth, development and patulin biosynthesis in P. expansum. ArfA is also involved in the virulence of P. expansum in fruit. • ArfA and SarA deletion inhibited the growth and development of P. expansum. • ArfA and SarA deletion restrained patulin biosynthesis of P. expansum. • ArfA deletion decreased the virulence of P. expansum in apple and pear fruit. [ABSTRACT FROM AUTHOR]

To study the control of postharvest decay caused by Colletotrichum gloeosporioides and Penicillium expansum, gamma irradiation alone or in combination with fumigation was evaluated to extend the shelf life of apples in South Korea. An irradiation dose of 2.0 kGy resulted in the maximum inhibition of C. gloeosporioides and P. expansum spore germination. The gamma irradiation dose required to reduce the spore germination by 90% was 0.22 and 0.35 kGy for C. gloeosporioides and P. expansum, respectively. Microscopic observations revealed that when the fungal spores were treated with gamma irradiation (4.0 kGy), conidial germination was stopped completely resulting in no germ tube formation in C. gloeosporioides. Treatment with the eco-friendly fumigant ethanedinitrile had a greater antifungal activity against C. gloeosporioides and P. expansum in comparison with the non-treated control under in vitro conditions. The in vitro antifungal effects of the gamma irradiation and fumigation treatments allowed us to further study the effects of the combined treatments to control postharvest decay on stored apples. Interestingly, when apples were treated with gamma irradiation in combined with fumigation, disease inhibition increased more at lower (< 0.4 kGy) than at higher doses of irradiation, suggesting that combined treatments reduced the necessary irradiation dose in phytosanitary irradiation processing under storage conditions.

Blue mold disease caused by Penicillium expansum is a major post-harvest disease of apples. In this research, the biochemical basis of apple resistance to this pathogen was studied in two relatively resistant and susceptible cultivars, Granny smith and Mashhad, respectively. The activities of catalase (CAT), peroxidase (POX), superoxide dismutase (SOD) and polyphenol oxidase (PPO) enzymes and polyphenol content were compared at different time intervals of 0 to 7 days. Based on the results, fruit polyphenol content of Granny smith was higher than that of Mashhad PPO, SOD and CAT activity was higher in Granny smith than Mashhad but CAT activity decreased three days post-treatment. No detectable difference was found in POX activities in the two cultivars. It is concluded that polyphenols contribute in apple resistance to blue mold. Activation of PPO and SOD, lack of POX activity and decrease of CAT activity, all together, could lead to a toxic environment around the blue mold fungus.

Dissemination and survival of ascomycetes is through asexual spores. The brlA gene encodes a C2H2-type zinc-finger transcription factor, which is essential for asexual development. Penicillium expansum causes blue mold disease and is the main source of patulin, a mycotoxin that contaminates apple-based food. A P. expansum PeΔbrlA deficient strain was generated by homologous recombination. In vivo, suppression of brlA completely blocked the development of conidiophores that takes place after the formation of coremia/synnemata, a required step for the perforation of the apple epicarp. Metabolome analysis displayed that patulin production was enhanced by brlA suppression, explaining a higher in vivo aggressiveness compared to the wild type (WT) strain. No patulin was detected in the synnemata, suggesting that patulin biosynthesis stopped when the fungus exited the apple. In vitro transcriptome analysis of PeΔbrlA unveiled an up-regulated biosynthetic gene cluster (PEXP_073960-PEXP_074060) that shares high similarity with the chaetoglobosin gene cluster of Chaetomium globosum. Metabolome analysis of PeΔbrlA confirmed these observations by unveiling a greater diversity of chaetoglobosin derivatives. We observed that chaetoglobosins A and C were found only in the synnemata, located outside of the apple, whereas other chaetoglobosins were detected in apple flesh, suggesting a spatial-temporal organization of the chaetoglobosin biosynthesis pathway.

Antifungal proteins of fungal origin (AFPs) are small, secreted, cationic, and cysteine-rich proteins. Filamentous fungi encode a wide repertoire of AFPs belonging to different phylogenetic classes, which offer a great potential to develop new antifungals for the control of pathogenic fungi. The fungus Penicillium expansum is one of the few reported to encode three AFPs each belonging to a different phylogenetic class (A, B, and C). In this work, the production of the putative AFPs from P. expansum was evaluated, but only the representative of class A, PeAfpA, was identified in culture supernatants of the native fungus. The biotechnological production of PeAfpB and PeAfpC was achieved in Penicillium chrysogenum with the P. chrysogenum-based expression cassette, which had been proved to work efficiently for the production of other related AFPs in filamentous fungi. Western blot analyses confirmed that P. expansum only produces PeAfpA naturally, whereas PeAfpB and PeAfpC could not be detected. From the three AFPs from P. expansum, PeAfpA showed the highest antifungal activity against all fungi tested, including plant and human pathogens. P. expansum was also sensitive to its self-AFPs PeAfpA and PeAfpB. PeAfpB showed moderate antifungal activity against filamentous fungi, whereas no activity could be attributed to PeAfpC at the conditions tested. Importantly, none of the PeAFPs showed hemolytic activity. Finally, PeAfpA was demonstrated to efficiently protect against fungal infections caused by Botrytis cinerea in tomato leaves and Penicillium digitatum in oranges. The strong antifungal potency of PeAfpA, together with the lack of cytotoxicity, and significant in vivo protection against phytopathogenic fungi that cause postharvest decay and plant diseases, make PeAfpA a promising alternative compound for application in agriculture, but also in medicine or food preservation.

Three new alkaloids (1, 4 and 8), together with nine known analogues (2, 3, 5–7, and 9–12), were isolated from the marine-derived fungus Penicillium expansum Y32. Their structures including the absolute configurations were elucidated by spectroscopic and Mosher’s and Marfey’s methods, along with quantum electronic circular dichroism (ECD) calculations. Each of the compounds was evaluated for cardiovascular effects in a live zebrafish model. All of the compounds showed a significant mitigative effect on bradycardia caused by astemizole (ASM) in the heart rate experiments. Compounds 4–6 and 8–12 exhibited potent vasculogenetic activity in vasculogenesis experiments. This is the first study to report that these types of compounds show cardiovascular effects in zebrafish. The results suggest that these compounds could be promising candidates for cardiovascular disease lead compounds.

Penicillium expansum destaca-se como fitopatógeno cosmopolita e altamente agressivo, responsável pelo bolor azul, doença que proporciona a perda de qualidade e quantidade pós colheita de frutos. Aplicações de produtos químicos é tradicionalmente o método de controle mais utilizado. No entanto, a bioprospecção de algas tem-se revelado uma fonte para uma grande quantidade de compostos antifúngicos. Desta maneira, o presente trabalho tem por objetivo avaliar os efeitos dos extratos etanólicos de sete microalgas e cinco macroalgas contra P. expasum. O potencial antifúngico foi avaliado analisando-se a porcentagem de germinação, o tamanho do tubo germinativo, a concentração mínima inibitória e a concentração efetiva mediana (CE50). O perfil espectrofotométrico foi realizado nos extratos que apresentaram efeito inibitório. Dentre as algas estudadas, os extratos de Chlorella sp. e H. pluvialis, nas concentrações finais de 18,8 e 125,95 mg.mL-1, foram capazes de inibir 100 e 91% da germinação, respectivamente. A CE50 foi de 2,93 e 61,20 mg.mL-1, para Chlorella sp. e H. pluvialis, respectivamente. Chlorella sp. apresentou picos de absorção na faixa da clorofila-a, já H. pluvialis apresentou um pico correspondente a faixa dos compostos fenólicos. Embora sejam necessários mais estudos para caracterizar os extratos, Chlorella sp. e H. pluvialis apresentaram efeito antifúngico promissor no controle de P. expansum.

The germination of fungal spores under non-isothermal conditions has been studied for several years, however, no mathematical model has been able to describe them suitably. Therefore, in this paper, we developed a new model to clarify the understanding of fungal spore germination under non-isothermal conditions by considering the effects of magnitude of condition change and difference in phase of spore during condition change on kinetic parameters, i.e. , the mean rate of germination ( μ ) and the time that half of spores had germinated ( t h ). To combine both effects into our new model, it was necessary to develop other two new models. The first model was used for estimating the swelling time of spores. The second model was the relationship between t h vs μ . After we had completed both models and successfully combined both effects into the new model for fungal spore germination under non-isothermal conditions, the new model was validated against experimental data on germination of Penicillium expansum spores in the literature. The prediction results showed that the new model well described the germination of this fungus under non-isothermal conditions., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 Published by Elsevier Ltd.)

Penicillium expansum is the causal agent of post-harvest blue mold in various fruits and serves as a model for understanding fungal pathogenicity and mycotoxin production. The relevance of oxidative stress response in the growth and virulence of P. expansum has been largely unexplored. Here, we identify the transcriptional factor PeAP1 as a regulator of oxidative stress response in P. expansum . Gene expression and protein abundance of PeAP1, as well as its nuclear localization, are specifically induced by H 2 O 2 . Deletion of PeAP1 results in increased sensitivity to H 2 O 2 , and PeAP1 mutants exhibit a variety of defects in hyphal growth and virulence. PeAP1 prevents the accumulation of both intracellular H 2 O 2 during vegetative growth and host-derived H 2 O 2 during biotrophic growth. Application of an antioxidant glutathione and a NADPH oxidase inhibitor, diphenylene iodonium, to the PeAP1 mutant partially restored fungal growth and virulence. RNA sequencing analysis revealed 144 H 2 O 2 -induced PeAP1 target genes, including four antioxidant-related genes, PeGST1 , PePrx1 , PePrx2 , and PeTRX2 , that were also demonstrated to be involved in oxidative stress response and/or virulence. Collectively, our results demonstrate the global regulatory role of PeAP1 in response to oxidative stress and provide insights into the critical role of the PeAP1-mediated oxidative stress response to regulate growth and virulence of P. expansum . IMPORTANCE Reactive oxygen species are the core of host plant defense and also play a vital role in the successful invasion of host plants by pathogenic fungi. Despite its importance, the relevance of oxidative stress response in fungal growth and virulence is poorly understood in P. expansum . In this study, we reveal that the transcription factor PeAP1 acts as a central regulator of oxidative stress response in P. expansum and that there is a major link between PeAP1-mediated oxidative stress response and fungal growth and virulence. To explore the underlying mechanisms, we performed comparative transcriptomic studies and identified a number of H 2 O 2 -induced PeAP1 target genes, including four novel ones, PePrx1 , PePrx2 , PeGST1 , and PeTRX2 , whose functions were linked to PeAP1 and pathogenicity. These findings provide novel insights into the regulation mechanism of PeAP1 on growth and virulence, which might offer promising targets for control of blue mold and patulin contamination.

Penicillium expansum (Link) Thom. is one of the most important postharvest pathogens of apple fruit worldwide. It causes blue mold, a decay that can lead to significant economic losses during storage, which can also impact fruit destined for processing due to the production of carcinogenic mycotoxin patulin. Apple fruit cvs. Idared, Golden Delicious and Braeburn with blue mold symptoms were collected from five storage facilities in Serbia and nine fungal isolates were obtained. Pathogenicity of the isolates was tested and proven by artificial inoculation of healthy apples cv. Idared. In order to identify the causal agents of decay, morphological and molecular methods were used. Colony morphology and microscopic features were observed on differential media, and isolates were tested for the production of cyclopiazonic acid. Molecular analysis included PCR amplification with species specific primers for P. expansum based on polygalacturonase gene (Pepg1), universal primers for internal transcribed spacer rDNA region and primers based on β-tubulin gene. All isolates formed compact blue green colonies with characteristic earthy odor. Conidiophores were terverticillate with smooth septate stipes and conidia were smooth, globose to subglobose, born in colums. The average size of conidia was 3.38 ± 0.49 (SD) x 3 ± 0.36 (SD) μm. Using species specific primers PEF/PER the texpected amplicons of ~404 bp were obtained in all nine tested isolates and PCR conducted with the Bt-LEVUp4/ Bt-LEV-Lo1 and universal ITS1/ITS4 primer pairs generated amplicons of the expected sizes of ~800 bp and ~600 bp, respectively. MegaBlast analyses of the 2X consensus of nucleotide sequences of the isolate JP1 partial β-tubulin gene and ITS region showed 99-100% and 100% similarity with several P. expansum sequences of corresponding regions of this species deposited in GenBank. Based on morphological and molecular features, the isolates obtained from decayed apple fruit collected in several storage facilities in Serbia were identified as P. expansum

Penicillium expansum 3.5425 was applied in solid-state fermentation (SSF) of agricultural wastes for polygalacturonase biosynthesis. Among various carbon additives, apple pomace was most suitable for the biosynthesis of polygalacturonase (1440.57 U/g). Optimization of medium parameters using rotational orthogonal design (ROD) experiment combined with optimal fermentation conditions resulted in a 2.72-fold increase in the polygalacturonase production. By using ammonium sulphate precipitation, ion-exchange and gel-permeation chromatography, the polygalacturonase produced by P. expansum 3.5425 was finally purified which had specific activity of 19269 U/mg and molecular weight of 30 kDa. The enzyme was remarkably active in the pH range of 3-5 and at 50°C, which makes it more acceptable in the industrial application. Besides, partially purified polygalacturonase (875.15 U/mL) was used for apple juice clarification and the clarity at 0.4 mL/kg was maximum, which reveals a great potential of polygalacturonase in food industry. [ABSTRACT FROM AUTHOR]

Penicillium expansum is a destructive phytopathogen provoking the blue mold decay of pome fruits and producing a polyketide-derived mycotoxin, patulin. In this study, the effects of exogenous essential oil decanal on development and patulin production of P. expansum were determined. Results indicated that 0.12 g L −1 decanal could significantly inhibit the growth of P. expansum in vitro . 0.24 g L −1 decanal showed a good controlling effect against the blue mold rot on apple and pear fruit. Besides, decanal could inhibit patulin production and the expression of genes involved in patulin biosynthesis. Through RNA sequencing approach, 1703, 3247 and 3963 genes were found which have changed abundantly after 6 h, 12 h and 18 h of incubation in decanal treated samples. Differentially expressed genes (DEGs) mainly participated in metabolism and genetic information processing. The expressions of about two-thirds of the DEGs were down-regulated. Among them, DEGs involved in oxidative phosphorylation, transcription, and translation would be partly responsible for growth inhibition of P. expansum . The findings would provide some new insights for exploring the possible antifungal mechanisms of decanal against P. expansum . [ABSTRACT FROM AUTHOR]

The effect of chlorine dioxide (ClO 2 ) on Penicillium expansum growth and patulin production in vitro and on its disease severity in apples was investigated. ClO 2 treatment significantly reduced the lesion diameter in apples infected with P. expansum and inhibited mycelial growth and spore germination. After ClO 2 treatment, P. expansum mycelial morphology was strongly affected, and a reduced spore plasma membrane integrity with an increased malondialdehyde (MDA) mycelial content was observed. Moreover, patulin production by P. expansum was reduced by ClO 2 treatment, both in apples and in PDB meidium. These data showed new and precise clues to the inhibitory effect of ClO 2 on P. expansum growth, and provided an effective method to ensure safety of apple products caused by P. expansum . [ABSTRACT FROM AUTHOR]

Mycotoxin patulin is one of the quality indicators for apple juice. Like other mycotoxins, it raises consumer health concerns. The issue of low quality is particularly relevant for apples provided by small producers, whose quality control may not be standardised. As sulphur dioxide (SO2) is common in fruit preservation against fungi, the aim of this study was to determine how efficient it is in degrading patulin in apple juices stored in real-life conditions. This included refrigerated (4 °C) and non-refrigerated warehouses/environments (30 °C) over 8, 10, 12, and 20 weeks of storage. Apple juice was diluted to 0.010 μg g-1, 0.050 μg g-1, and 0.100 μg g-1 of patulin. SO2 was added to each sample in the amounts of 250 μg mL-1 and 50 μg mL-1. Untreated juice samples for each patulin concentration served as controls under the same experimental conditions. Patulin content was determined with high performance liquid chromatography. The best degradation was observed with 250 μg mL-1 of SO2 at 30 °C regardless of the patulin baseline concentration. Although treatment with SO2 and refrigeration did not fully remove patulin, it was highly efficient over twelve weeks of storage. Our results suggest that patulin levels can be reduced between 33 and 100 % at 30 °C and up to 100 % at 4 °C. [ABSTRACT FROM AUTHOR]