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Blue mold caused by Penicilliumexpansum (P. expansum) causes severe fruit losses, and there is an urgent need to explore safe natural products to control post-harvest diseases and investigate potential antifungal mechanisms. In this study, flavonoids (GBLF) were extracted and purified from mature Ginkgo biloba leaves (GBL). According to an analysis of UV-visible spectroscopy, FTIR, and LC-MS, GBLF contained 10 flavonoids, including 8 quercetin and kaempferol derivatives. The inhibition halo diameter by GBLF ethanol solution reached a maximum of 11.2 ± 0.3 mm, which significantly inhibited the growth of P. expansum. In the GBLF ethanol solution treatment trial, the mycelial cells of P. expansum reached their maximum cell conductivity, protein leakage rate, and malondialdehyde (MDA) content at 48 h, with values of 3.89 ± 0.17 ms/cm, 5.22 ± 0.08 mg/L, and 5.76 ± 0.09 mmol/kg, respectively, which were 2.7, 13.74, and 4.76 times higher than those of the control. Compared with 12 h, the activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) in the enzyme antioxidant system were 3.38 ± 0.11 U/mg, 5.23 ± 0.09 U/mg, and 2.66 ± 0.10 U/mg, respectively, which decreased by 30.2%, 20.09%, and 51.47%. In conclusion, quercetin and kaempferol derivatives in GBLF may act on P. expansum by increasing the permeability of cell membranes, reducing enzymatic antioxidant activity, and accelerating lipid peroxidation. [ABSTRACT FROM AUTHOR]

Deoxyacetyl-donacinoic acid B (1), a new bergamotane-type sesquiterpenoid, was isolated from the rice solid fermentation of Penicillium expansum GY618. The structure of compound 1 was well established by the detailed interpretation of NMR and HR-ESI-MS data, as well as ECD measurement powered by molecular calculation. The antibacterial activities of compound 1 were evaluated. [ABSTRACT FROM AUTHOR]

BACKGROUND: Fresh ginseng is typically accompanied by soil after harvest, leading to contamination with harmful fungi during storage and distribution. In this study, we investigated the incidence of fungal contamination in fresh ginseng (5–6 years old) purchased from 22 different stores in Geumsan, Korea. RESULTS: The incidence of fungal contamination in the samples was 67.4–111.5%. Fusarium solani was the most abundant species in the head (38.5%) and fine root (19.3%) parts of the ginseng samples, whereas F. oxysporum was the most abundant in the main root (22.0%) part. We isolated Aspergillus, Fusarium and Penicillium spp. (total number of isolates: 395) from the ginseng samples, and 138 isolates were identified using phylogenetic analysis. Polymerase chain reaction‐based screening of 65 mycotoxin‐producing species revealed that two P. expansum isolates were positive for citrinin and/or patulin, and five F. oxysporum isolates were positive for fumonisin biosynthesis gene. One P. expansum isolate produced 738.0 mg kg−1 patulin, and the other produced 10.4 mg kg−1 citrinin and 12.0 mg kg−1 patulin on potato dextrose agar (PDA) medium. Among the 47 representative F. oxysporum isolates, 43 (91.5%) produced beauvericin (0.1–15.4 mg kg−1) and four of them (8.5%) produced enniatin B and enniatin B1 (0.1–1.8 mg kg−1) as well. However, none of these toxins was detected in fresh ginseng samples. CONCLUSION: Fusarium solani and F. oxysporum were the most abundant species in fresh ginseng samples. Most F. oxysporum (43) and P. expansum (2) strains isolated from fresh ginseng produced beauvericin and enniatins (B and B1), and patulin or citrinin, respectively, on PDA medium. This is the first report of the mycotoxigenic potential of P. expansum and F. oxysporum strains isolated from fresh ginseng. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Blue mold caused by Penicillium expansum infection results in severe postharvest deterioration of apples. Salicylic acid (SA) is an effective elicitor of fruit resistance. However, the metabolic mechanism of P. expansum infection of apples and the SA-mediated metabolic responses are still unknown. In this study, the metabolite changes during P. expansum infection of apples and SA-mediated disease resistance were explored by performing ultra-performance liquid chromatography and quadrupole-time-of-flight mass spectrometry. A total of 472 different metabolites were identified between the five groups of sample comparisons, and the correlated metabolic pathways were revealed by bioinformatics analysis. The upregulation of the tricarboxylic acid (TCA) cycle, galactose metabolism, and starch and sucrose metabolism reflected energy conversion for P. expansum invasion and fruit disease resistance. Changes in glyoxylate and dicarboxylate metabolism and carbapenem biosynthesis reflected the biosynthesis of virulence factors and secondary metabolites for fungal infection. Metabolic pathways related to apple natural disease resistance mainly included the upregulation of secondary metabolite biosynthesis and sphingolipid metabolism. SA promoted the TCA cycle, reactive oxygen metabolism, and secondary metabolite biosynthesis of apples for disease resistance. This study revealed the metabolic pathways of P. expansum infection of apples and SA-mediated disease resistance, which helps to improve the understanding of the pathogenic mechanism and disease control. [ABSTRACT FROM AUTHOR]

Introduction: Penicillium expansum is a harmful plant fungal pathogen that causes blue mold disease and produces mycotoxin patulin, leading to huge economic losses and food safety hazard. Set1 associated complex Set1/COMPASS deposits the methylation at lysine 4 of histone H3, which is associated with gene expression in diverse biological processes of fungi. However, the function and underlying mechanisms of Set1/COMPASS are poorly defined in P. expansum. Objectives: The study aimed to identify Set1/COMPASS and investigate its regulation mechanisms on growth, pathogenicity, and patulin biosynthesis of P. expansum. Methods: Analyses of phylogenetic relationship, conserved structural domain, and gene deletion were used to identify components of Set1/COMPASS. Phenotype analysis and stress tolerance test of gene deletion mutants were conducted to analyze the function of these components. Yeast two-hybrid, Co-Immunoprecipitation (Co-IP), and point mutation were performed to verify the protein interaction. Western blot was conducted for detection of H3K4 methylation levels. Results: P. expansum owns six components of Set1/COMPASS besides PeSet1. Absence of each component resulted in reduction of H3K4 methylation levels and impaired growth, pathogenicity, and patulin biosynthesis, as well as altered stress responses of P. expansum. One component PeBre2p was found to interact with the conserved global regulator PeVelB (VelvetLike protein B) at Asp294 of PeBre2p. This interaction affected fungal growth and utilization of fructose, lactose, glycine, and proline in P. expansum. Conclusion: This study revealed the important roles of Set1/COMPASS in P. expansum and clarified for the first time the combined regulation of PeBre2p and PeVelB in fungal growth and nutrition utilization. These results will provide potential targets for the control of blue mold disease.

[Display omitted] Penicillium expansum is a harmful plant fungal pathogen that causes blue mold disease and produces mycotoxin patulin, leading to huge economic losses and food safety hazard. Set1 associated complex Set1/COMPASS deposits the methylation at lysine 4 of histone H3, which is associated with gene expression in diverse biological processes of fungi. However, the function and underlying mechanisms of Set1/COMPASS are poorly defined in P. expansum. The study aimed to identify Set1/COMPASS and investigate its regulation mechanisms on growth, pathogenicity, and patulin biosynthesis of P. expansum. Analyses of phylogenetic relationship, conserved structural domain, and gene deletion were used to identify components of Set1/COMPASS. Phenotype analysis and stress tolerance test of gene deletion mutants were conducted to analyze the function of these components. Yeast two-hybrid, Co-Immunoprecipitation (Co-IP), and point mutation were performed to verify the protein interaction. Western blot was conducted for detection of H3K4 methylation levels. P. expansum owns six components of Set1/COMPASS besides PeSet1. Absence of each component resulted in reduction of H3K4 methylation levels and impaired growth, pathogenicity, and patulin biosynthesis, as well as altered stress responses of P. expansum. One component PeBre2p was found to interact with the conserved global regulator PeVelB (Ve lvet L ike protein B) at Asp294 of PeBre2p. This interaction affected fungal growth and utilization of fructose, lactose, glycine, and proline in P. expansum. This study revealed the important roles of Set1/COMPASS in P. expansum and clarified for the first time the combined regulation of PeBre2p and PeVelB in fungal growth and nutrition utilization. These results will provide potential targets for the control of blue mold disease. [ABSTRACT FROM AUTHOR]

This study investigates the impact of polyphenols on the susceptibility of traditional and conventional apple varieties to Penicillium expansum infection and subsequent patulin biosynthesis during cold storage. Traditional varieties, notably 'Bobovec', exhibit significantly higher levels of total polyphenols (650.56 ± 9.85 mg/L) and flavonoids (184.11 ± 1.48 g/kg dw) compared to conventional ones after six months of storage, accompanied by the identification of key polyphenols such as chlorogenic acid, epicatechin, phloridzin, quercetin and procyanidins B1 and B2. These traditional varieties demonstrate enhanced resistance to P. expansum infection, as evidenced by prolonged periods for colony formation, particularly 'Bobovec' with an average of 384 h. Furthermore, the traditional variety 'Winter Banane' and conventional varieties 'Idared' and 'Fuji' showed increased patulin biosynthesis postinoculation, indicating higher susceptibility to fungal infection. The findings underscore the potential of polyphenols from traditional apple varieties as natural defences against fungal infections, suggesting the importance of selecting or breeding varieties with higher polyphenol content to improve resistance to postharvest pathogens, thereby enhancing the quality and safety of stored apples. [ABSTRACT FROM AUTHOR]

Mango fruits' quality, marketability, and shelf life are significantly influenced by postharvest decay. Mango fruit disease development during storage is inhibited by fungicides. The objective of this investigation was to assess the relative effectiveness of two fungicides, azoxystrobin 18.2% + difenoconazole 11.4% SC and hexaconazole 5% SC, in mitigating postharvest deterioration of mango cv. 'Langra' during low temperature storage. Three pathogens were found associated with postharvest decay of mango, i.e. Colletotrichum gloeosporioides, Alternaria alternata , and Penicillium expansum. In comparison to untreated ones, the preharvest application of fungicide treatments provided noticeably better disease control. The foliar application of azoxystrobin 18.2% + difenoconazole 11.4% SC (0.1%) 15 days before the harvesting of fruits significantly improved fruit firmness, soluble solid content, titratable acidity, reduced the disease incidence, percentage disease index, and lesion diameter followed by the application of hexaconazole 5% SC (0.1%) compared to the control. Furthermore, it was found that pre-harvest fungicide spraying of azoxystrobin 18.2% + difenoconazole 11.4% SC (0.1%) was an effective treatment for lowering postharvest deterioration and enhancing the physio-chemical characteristics of mango fruits during low-temperature storage. [ABSTRACT FROM AUTHOR]

Penicillium expansum is the predominant causal agent causing blue mold in postharvest fresh Codonopsis pilosula during storage. The pathogen reduces the yield and affects the quality of C. pilosula and even generates patulin, threatening human health. In this study, postharvest fresh, healthy C. pilosula was sprayed with P. expansum, and the control effect of ozone on postharvest diseases of C. pilosula was studied, and the effect of ozone on the contents in the main active ingredients of C. pilosula was compared; finally, the effect of ozone on reactive oxygen species (ROS) metabolism in C. pilosula was analyzed. The results showed that 2 mg L−1 ozone application significantly inhibited the occurrence of postharvest blue mold caused by P. expansum, reduced weight loss rate, controlled the accumulation of patulin and maintained the contents of the main active components in C. pilosula. The study will provide a theoretical basis for ozone treatment to control the occurrence of postharvest diseases of C. pilosula. [ABSTRACT FROM AUTHOR]

کاربرد اسانس گیاهان دارویی، به عنوان جایگزین قارچ­کش ­های شیمیایی خطرناک، به دلیل حلالیت کم در آب، پایداری شیمیایی ضعیف و طبیعت فرار آنها، بسیار محدود است. برای رفع این مشکل، اخیرا کپسوله‌سازی در مقیاس نانومتری اسانس ­ها و همراه کردن آن با پوشش ­های پلیمری پیشنهاد شده است. در این مطالعه ابتدا نانوامولسیون اسانس ­های مرزه خوزستانی (حاوی کارواکرول %4/87) و نعناع­ فلفلی (حاوی منتون %6/33 و منتول %3/35) به ترتیب با میانگین اندازه ذره 295 و 186 نانومتر تهیه شد و پس از اثبات کارایی آنها در مهار و کشتن قارچ Penicillium expansum، در مخلوط با پوشش پلی ساکاریدی کتیرا (5%/0 و %1) برای مهار پوسیدگی پنِیسیلیومی میوه گوجه فرنگی و بهبود شاخص­ های فیزیکوشیمیایی آن طی دوره 10 و 20 روز نگهداری در دمای 10 درجه سلسیوس بررسی شد. تیمارهای نانوامولسیون اسانس مزره %1/0 در ترکیب با کتیرا %5/0 و %1 بیشترین تاثیر را در مهار پوسیدگی پنیسیلیومی میوه گوجه فرنگی نشان داده و از ایجاد پوسیدگی ممانعت کردند. تیمار نانوامولسیون اسانس نعناع ­فلفلی در ترکیب با کتیرا در مرتبه بعدی قرار گرفت. علاوه براین اثر تیمارهای برتر روی برخی شاخص­ های فیزیکوشیمیایی میوه نشان از تاثیر مثبت معنی ­دار آنها روی شاخص‌های سفتی میوه و مواد جامد محلول (TSS) میوه می ­باشد. علاوه براین، محتوای فنول کل میوه های تیمار شده بطور معنی داری بیشتر از میوه­ های شاهد سالم بود. به هرحال به نظر می­ رسد نانوکپسوله ­سازی اسانس­ های با فعالیت ضدقارچی و آنتی­اکسیدانی و ترکیب کردن آنها با پوشش پلیمری کتیرا، افزایش کیفیت و ماندگاری میوه در طی انبارداری را در پی داشته باشد.

Patulin is a secondary metabolite primarily synthesized by the fungus Penicillium expansum, which is responsible for blue mold disease on apples. The latter are highly susceptible to fungal infection in the postharvest stages. Apples destined to produce compotes are processed throughout the year, which implies that long periods of storage are required under controlled atmospheres. P. expansum is capable of infecting apples throughout the whole process, and patulin can be detected in the end-product. In the present study, 455 apples (organically and conventionally grown), destined to produce compotes, of the variety "Golden Delicious" were sampled at multiple postharvest steps. The apple samples were analyzed for their patulin content and P. expansum was quantified using real-time PCR. The patulin results showed no significant differences between the two cultivation techniques; however, two critical control points were identified: the long-term storage and the deck storage of apples at ambient temperature before transport. Additionally, alterations in the epiphytic microbiota of both fungi and bacteria throughout various steps were investigated through the application of a metabarcoding approach. The alpha and beta diversity analysis highlighted the effect of long-term storage, causing an increase in the bacterial and fungal diversity on apples, and showed significant differences in the microbial communities during the different postharvest steps. The different network analyses demonstrated intra-species relationships. Multiple pairs of fungal and bacterial competitive relationships were observed. Positive interactions were also observed between P. expansum and multiple fungal and bacterial species. These network analyses provide a basis for further fungal and bacterial interaction analyses for fruit disease biocontrol. [ABSTRACT FROM AUTHOR]

Pathogenesis of P. expansum involved different processes and one of them is the recognition between pathogen-host, which in the case of P. expansum is preferably pome fruit. In this work, the possible mechanisms connected to host recognition are addressed through the generation of a subtractive library carried out during the incompatible P. expansum-orange interaction in the initial stages of infection. The generated library was analyzed by massive sequencing and bioinformatic analysis. Of the identified genes, a total of 24 were selected for subsequent expression analysis by RT-qPCR in two incompatible interaction situations. The characterization of the overexpressed genes revealed the presence of CWDEs, ATPases, aldolases, detoxifying enzymes and virulent determinants that could act as effectors related to fungal virulence independently of the host. However, several identified genes, which could not be associated with the virulence of P. expansum under compatible conditions, were related to enzymes to obtain the nutrients necessary for the growth and development of the pathogen under stress conditions through basal metabolism that contributes to expand the range of adaptation of the pathogen to the environment and different hosts.

Penicillium expansum, a common spoilage organism in postharvest fruits, can cause fruit decay and deterioration and endanger human health. It is of great significance to investigate the antimicrobial mechanism of the antimicrobial peptide from Paenibacillus ehimensis on P. expansum spores. The antimicrobial activity of the antimicrobial peptide against P. expansum spores was determined by using the two-fold dilution method as well as measuring the time-killing curve. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to evaluate the effect of the antimicrobial peptide on the ultrastructure of P. expansum spores. The effects of the antimicrobial peptide on the cell membrane and reactive oxygen species (ROS) accumulation of P. expansum were analyzed by fluorescence probes. The results showed that the minimum inhibitory concentration (MIC) of the antimicrobial peptide against P. expansum spores was 3.5 AU/mL. The spore germination rate was significantly decreased by 28.30%, 84.57% and 100% by the antimicrobial peptide at concentrations of 0.5 MIC, 1 MIC and 2 MIC compared with the blank control (P < 0.05). After treatment with the antimicrobial peptide, the spores appeared seriously sunken, the intracellular contents were leaked out, and the morphology and structure were changed. The antimicrobial peptide damaged the cell wall of P. expansum, resulting in the leakage of alkaline phosphatase. The antimicrobial peptide depolarized the cell membrane potential in a dose-dependent manner, and increased the cell membrane permeability, leading to K+ leakage. The fluidity of the cell membrane was increased, which in turn resulted in a significant decrease in DPH fluorescence intensity (P < 0.05). The integrity of the cell membrane was damaged by the antimicrobial peptide, so the fluorescence intensity of SYTOX-Green and the contamination rate of PI were increased. Moreover, the antimicrobial peptide at 1 MIC and 2 MIC increased the fluorescence intensity of DCFH-DA significantly (P < 0.05) and resulted in ROS accumulation, which affected the physiology and metabolism of P. expansum spores. This study indicated that the target sites of the antimicrobial peptide against P. expansum spores were mainly the cell membrane and ROS metabolism.

Hasat sonrası elmalarda oldukça yaygın görülen Penicillim expansum’un neden olduğu mavi küf dünya çapında önemli ekonomik kayıplara neden olmaktadır. Bu çalışmada Lamiaceae, Asteraceae, Caprifoliaceae, Papaveraceae familyalarına ait 14 bitki türü P. expansum’un misel büyümesinin kontrolü için in vivo ve in vitro etkinlikleri açısından değerlendirildi. İn vivo sonuçlara göre P. expansum’un misel büyümesini Lamiaceae familyasına ait Origanum vulgare ve Thymus longicaulis sırası ile %100 ve %87.11’lik oranlarında inhibe etti. En düşük MİK değerini O. vulgare sulu ekstraktı gösterdi (250 µg/mL). O. vulgare sulu ekstraktları (32 mg/mL) elmada yapay olarak oluşturulan mavi küf enfeksiyonunu %69.21 oranında engelledi. SEM analizinde P. expansum’un hifal yapısı üzerine O. vulgare ve T. longicaulis’in çökertme, yassılaşma ve kırışık hücre yüzeyli hücreler etkileri gözlendi. Mavi küf enfeksiyonlarını kontrol edebilmek için O. vulgare sulu ekstraktının doğal bir antifungal madde olarak değerlendirilebileceğini önerebiliriz.

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 (th). 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 th 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.

Blue mold, a postharvest disease of pome fruits, is caused by the filamentous fungus Penicillium expansum. In addition to the economic losses caused by P. expansum, food safety can be compromised, as this pathogen is mycotoxigenic. In this study, forward and reverse genetic approaches were used to identify genes involved in blue mold infection in apple fruits. For this, we generated a random T-DNA insertional mutant library. A total of 448 transformants were generated and screened for the reduced decay phenotype on apples. Of these mutants, six (T-193, T-275, T-434, T-588, T-625, and T-711) were selected for continued studies and five unique genes were identified of interest. In addition, two deletion mutants (Δt-625 and Δt-588) and a knockdown strain (t-434KD) were generated for three loci. Data show that the ∆t-588 mutant phenocopied the T-DNA insertion mutant and had virulence penalties during apple fruit decay. We hypothesize that this locus encodes a glyoxalase due to bioinformatic predictions, thus contributing to reduced colony diameter when grown in methylglyoxal (MG). This work presents novel members of signaling networks and additional genetic factors that regulate fungal virulence in the blue mold fungus during apple fruit decay. [ABSTRACT FROM AUTHOR]

Blue mold is an economically significant postharvest disease of pome fruit that is primarily caused by Penicillium expansum. To manage this disease and sustain product quality, novel decay intervention strategies are needed that also maintain long-term efficacy. Biocontrol organisms and natural products are promising tools for managing postharvest diseases. Here, two Penicillium chrysogenum isolates, 404 and 413, were investigated as potential biocontrol agents against P. expansum in apple. Notably, 404 and 413 were non-pathogenic in apple, yet they grew vigorously in vitro when compared to the highly aggressive P. expansum R19 and Pe21 isolates. Whole-genome sequencing and species-specific barcoding identified both strains as P. chrysogenum. Each P. chrysogenum strain was inoculated in apple with the subsequent co-inoculation of R19 or Pe21 simultaneously, 3, or 7 days after prior inoculation with 404 or 413. The co-inoculation of these isolates showed reduced decay incidence and severity, with the most significant reduction from the longer establishment of P. chrysogenum. In vitro growth showed no antagonism between species, further suggesting competitive niche colonization as the mode of action for decay reduction. Both P. chrysogenum isolates had incomplete patulin gene clusters but tolerated patulin treatment. Finally, hygromycin resistance was observed for both P. chrysogenum isolates, yet they are not multiresistant to apple postharvest fungicides. Overall, we demonstrate the translative potential of P. chrysogenum to serve as an effective biocontrol agent against blue mold decay in apples, pending practical optimization and formulation. [ABSTRACT FROM AUTHOR]

A chemical investigation on an endophytic fungus Penicillium expansum isolated from the medicinal plant Plantago depressa Willd. (Plantaginaceae) afforded one new diketopiperazine-type alkaloid, namely penicimine A (1), as well as two known congeners (2 and 3). Their structures were elucidated by widespread spectroscopic data, and the absolute configurations of 1 and 2 were further confirmed by single-crystal X-ray diffraction analyses. Compound 1 represented the first example of benzyl-containing diketopiperazine-type alkaloid bearing a methyl group attached at C-15 position. Compound 1 showed anti-inflammatory activity against LPS-induced nitric oxide (NO) production in RAW264.7 mouse macrophages with an IC50 value of 25.65 μM. [ABSTRACT FROM AUTHOR]

Penicillium expansum is the most popular post-harvest pathogen and causes blue mold disease in pome fruit and leads to significant economic losses worldwide every year. However, the fundamental regulation mechanisms of growth in P. expansum are unclear. Recently, non-coding RNAs (ncRNAs) have attracted more attention due to critical roles in normalizing gene expression and maintaining cellular genotypes in organisms. However, the research related to ncRNAs in P. expansum have not been reported. Therefore, to provide an overview of ncRNAs on composition, distribution, expression changes, and potential targets in the growth process, a comparative transcriptomic analysis was performed on spores and mycelia of P. expansum in the present study. A total of 2595 novel mRNAs, 3362 long non-coding RNAs (lncRNAs), 10 novel microRNAs (miRNAs), 86 novel small interfering RNAs (siRNAs), and 11,238 circular RNAs (circRNAs) were predicted and quantified. Of these, 1482 novel mRNAs, 5987 known mRNAs, 2047 lncRNAs, 40 miRNAs, 38 novel siRNAs, and 9235 circRNAs were differentially expressed (DE) in response to the different development stages. Afterward, the involved functions and pathways of DE RNAs were revealed via Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) database enrichment analysis. The interaction networks between mRNAs, lncRNAs, and miRNAs were also predicted based on their correlation coefficient of expression profiles. Among them, it was found that miR168 family members may play important roles in fungal growth due to their central location in the network. These findings will contribute to a better understanding on regulation machinery at the RNA level on fungal growth and provide a theoretical basis to develop novel control strategies against P. expansum. [ABSTRACT FROM AUTHOR]

β-1,3-glucanase plays an important role in the biodegradation, reconstruction, and development of β-1,3-glucan. An endo-β-1,3-glucanase which was encoded by PeBgl1 was expressed, purified and characterized from Penicillium expansum for the first time. The PeBgl1 gene was amplified and transformed into the competent cells of E. coli Rosetta strain with the help of the pET-30a cloning vector. The recombinant protein PeBgl1 was expressed successfully at the induction conditions of 0.8 mmol/L IPTG at 16 °C for 16 h and then was purified by nickel ion affinity chromatography. The optimum reaction temperature of PeBgl1 was 55 °C and it had maximal activity at pH 6.0 according to the enzymatic analysis. Na2HPO4-NaH2PO4 buffer (pH 6.0) and NaCl have inhibitory and enhancing effects on the enzyme activities, respectively. SDS, TritonX-100 and some metal ions (Mg2+, Ca2+, Ba2+, Cu2+, and Zn2+) have an inhibitory effect on the enzyme activity. The results showed that PeBgl1 protein has good enzyme activity at 50–60 °C and at pH 5.0–9.0, and it is not a metal dependent enzyme, which makes it robust for storage and transportation, ultimately holding great promise in green biotechnology and biorefining. [ABSTRACT FROM AUTHOR]

ABSTRACT 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 H2O2. Deletion of PeAP1 results in increased sensitivity to H2O2, and PeAP1 mutants exhibit a variety of defects in hyphal growth and virulence. PeAP1 prevents the accumulation of both intracellular H2O2 during vegetative growth and host-derived H2O2 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 H2O2-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 H2O2-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 is a main producer of patulin that causes severe postharvest decay and food safety issues in the fruit industry. Development, pathogenicity, and patulin production of P. expansum are strongly influenced by the PacC-pH signaling pathway. Global transcription factor PacC regulates various fungal biological processes through a complicated molecular network. In the present study, three Ena family genes (PeEnas), PeEnaA, PeEnaB, and PeEnaC, as important downstream targets of PePacC, were identified in P. expansum. Deletion of PeEnaA, PeEnaB, and PeEnaC showed little effect on mycelial growth under alkaline or high salinity conditions, but double and triple deletion of these genes impaired the virulence of P. expansum on apple fruit. Notably, patulin biosynthesis of P. expansum was distinctly inhibited in the deletion mutants of PeEnas. PeEnas regulated expressions of the patulin gene cluster, AP1, CreA, Sge1, and Hog1 at the transcriptional level and played roles in maintaining membrane potential. Overexpression of PeEnaC in ΔPePacC restored the patulin production defect of ΔPePacC. Our results indicated that, as downstream targets of PePacC, the PeEna family proteins play a crucial role in patulin biosynthesis in P. expansum. [ABSTRACT FROM AUTHOR]

Communesins are rare alkaloids isolated from fungi of the genus Penicillium. In this work, the extract of a marine‐derived Penicillium expansum strain was studied using targeted molecular networking approach allowing to detect 65 communesins including 55 new ones. A fragmentation pattern for dimethylvinyl communesins was established and a script was implemented allowing to predict the structure and map all communesins in a global molecular network. A semisynthetic strategy was carried out to obtain some minor congeners from the two isolated communesins A and B. Nine communesins were then synthetised: two of them were already described as produced by the studied strain; four are new natural products which occurrence in the extracts was confirmed; three are new semi‐synthetic analogues never described so far. These communesins were evaluated for their cytotoxicity on two human cancer cell lines KB and MCF‐7 leading to a preliminary study of their structure‐activity relationships. [ABSTRACT FROM AUTHOR]

Onion is one of the most important salad and vegetable plants in all parts of Pakistan. Onions in storage are being affected by different types of diseases, but Blue Mold of Onions is one of the most important detrimental post-harvest diseases of onions. The research was conducted in the Plant Pathology Laboratory at Sindh Agriculture University, Tando Jam, to manage Penicillium expansum by applying different Botanical extracts, Viz., Caramon, Garlic and Neem. The efficacy of all three botanicals was tested on storage onion with three replications and data was collected at four days' intervals. After statistical analysis, it was observed that all three botanicals cause significant reductions in the rot severity of onion in storage: among the three botanicals, Neem was found most effective in reducing rot severity, followed by garlic and caramon. [ABSTRACT FROM AUTHOR]

One of the most significant challenges associated with postharvest apple deterioration is the blue mold caused by Penicillium expansum, which leads to considerable economic losses to apple production industries. Apple fruits are susceptible to mold infection owing to their high nutrient and water content, and current physical control methods can delay but cannot completely inhibit P. expansum growth. Biological control methods present promising alternatives; however, they are not always cost effective and have application restrictions. P. expansum infection not only enhances disease pathogenicity, but also inhibits the expression of host-related defense genes. The implementation of new ways to investigate and control P. expansum are expected with the advent of omics technology. Advances in these techniques, together with molecular biology approaches such as targeted gene deletion and whole genome sequencing, will lead to a better understanding of the P. expansum infectious machinery. Here, we review the progress of research on the blue mold disease caused by P. expansum in apples, including physiological and molecular infection mechanisms, as well as various methods to control this common plant pathogen. [ABSTRACT FROM AUTHOR]

erg4 is a key gene for ergosterol biosynthesis in filamentous fungi, but its function in Penicillium expansum remains unknown. Our results showed that P. expansum contains three erg4 genes, including erg4A, erg4B and erg4C. The expression levels of the three genes showed differences in the wild-type (WT) strain, and the expression level of erg4B was the highest, followed by erg4C. Deletion of erg4A, erg4B or erg4C in the WT strain revealed functional redundancy between them. Compared to the WT strain, erg4A, erg4B or erg4C knockout mutants reduced ergosterol levels, with erg4B deletion having the greatest effect. Furthermore, deletion of the three genes reduced sporulation of the strain, and Δerg4B and Δerg4C mutants showed defective spore morphology. In addition, Δerg4B and Δerg4C mutants were found to be more sensitive to cell wall integrity and oxidative stress. However, deletion of erg4A, erg4B or erg4C had no significant effect on colony diameter, spore germination rate, conidiophore structure of P. expansum or pathogenicity to apple fruit. Taken together, erg4A, erg4B and erg4C have redundant functions and are all involved in ergosterol synthesis and sporulation in P. expansum. In addition, erg4B and erg4C contribute to spore morphogenesis, cell wall integrity and response to oxidative stress in P. expansum. [ABSTRACT FROM AUTHOR]

Apple blue mold is a significant postharvest disease caused by Penicillium expansum. pH modification in colonized tissues leads to the production of organic substances, the modulation of enzymes, and then increases fungal pathogenicity. This study evaluated Penicillium expansum-inoculated apple fruits' quality responding to pH treatments ranging from 2.5 to 8.5 and analyzed the reactive oxygen species (ROS) metabolism modulation in inoculated apple fruits at the same pH. The results showed that the fruit quality of the firmness, total soluble solids, and titratable acid displayed a quick loss at pHs 5.0 and 7.0, compared with 2.5 and 8.5. Similarly, higher disease incidence was observed at pHs 5.0 and 7.0. Apple fruits infected with P. expansum at pHs 2.5 and 8.5 had less content of O2•−, H2O2, and malondialdehyde (MDA); lower enzymatic activity of NADPH oxidase (NOX); and greater cell membrane integrity than those at pHs 5.0 and 7.0. The analysis of the antioxidant enzymatic activities showed upregulation of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), and glutathione reductase (GR) at pHs 2.5 and 8.5 compared with those at pHs 5.0 and 7.0. Similar trends were shown in ascorbic acid and glutathione. These results support the hypothesis that inoculated apple fruits at pHs 2.5 and 8.5 improve resistance to P. expansum by modulating ROS metabolism, compared with pHs 5.0 and 7.0. [ABSTRACT FROM AUTHOR]

Blue mold decay caused by Penicillium expansum is one of the most important postharvest diseases of grapes, leading to considerable economic losses. Regarding the increasing demand for pesticide-free foods, this study aimed to find potential yeast strains for biological control of blue mold on table grapes. A total of 50 yeast strains were screened for antagonistic activity against P. expansum using the dual culture method and six strains significantly inhibited the fungal growth. All six yeast strains (Coniochaeta euphorbiae , Auerobasidium mangrovei , Tranzscheliella sp., Geotrichum candidum , Basidioascus persicus , and Cryptococcus podzolicus) reduced the fungal growth (29.6–85.0%) and the decay degree of wounded grape berries inoculated with P. expansum while G. candidum was found to be the most efficient biocontrol agent. On the basis of antagonistic activity, the strains were further characterized by in vitro assays involving inhibition of conidial germination, production of volatile compounds, iron competition, production of hydrolytic enzymes, biofilm-forming capacity, and exhibited three or more putative mechanisms. To our knowledge, the yeasts are reported for the first time as potential biocontrol agents against the blue mold of grapes but more study is required to evaluate their efficiency related to field application. [Display omitted] • Fifty yeast strains were screened for antagonistic activity against P. expansum in vitro. • Six novel yeast strains with biocontrol activity against P. expansum on grapes were introduced. • Treatment of grapes with G. candidum resulted in an 85% reduction in P. expansum growth. • G. candidum showed higher biofilm-forming capacity in vitro than the other strains. [ABSTRACT FROM AUTHOR]

Penicillium expansum is the predominant causal agent causing blue mold in postharvest fresh Codonopsis pilosula during storage. The pathogen reduces the yield and affects the quality of C. pilosula and even generates patulin, threatening human health. In this study, postharvest fresh, healthy C. pilosula was sprayed with P. expansum, and the control effect of ozone on postharvest diseases of C. pilosula was studied, and the effect of ozone on the contents in the main active ingredients of C. pilosula was compared; finally, the effect of ozone on reactive oxygen species (ROS) metabolism in C. pilosula was analyzed. The results showed that 2 mg L−1 ozone application significantly inhibited the occurrence of postharvest blue mold caused by P. expansum, reduced weight loss rate, controlled the accumulation of patulin and maintained the contents of the main active components in C. pilosula. The study will provide a theoretical basis for ozone treatment to control the occurrence of postharvest diseases of C. pilosula.

Patulin is a secondary metabolite primarily synthesized by the fungus Penicillium expansum, which is responsible for blue mold disease on apples. The latter are highly susceptible to fungal infection in the postharvest stages. Apples destined to produce compotes are processed throughout the year, which implies that long periods of storage are required under controlled atmospheres. P. expansum is capable of infecting apples throughout the whole process, and patulin can be detected in the end-product. In the present study, 455 apples (organically and conventionally grown), destined to produce compotes, of the variety “Golden Delicious” were sampled at multiple postharvest steps. The apple samples were analyzed for their patulin content and P. expansum was quantified using real-time PCR. The patulin results showed no significant differences between the two cultivation techniques; however, two critical control points were identified: the long-term storage and the deck storage of apples at ambient temperature before transport. Additionally, alterations in the epiphytic microbiota of both fungi and bacteria throughout various steps were investigated through the application of a metabarcoding approach. The alpha and beta diversity analysis highlighted the effect of long-term storage, causing an increase in the bacterial and fungal diversity on apples, and showed significant differences in the microbial communities during the different postharvest steps. The different network analyses demonstrated intra-species relationships. Multiple pairs of fungal and bacterial competitive relationships were observed. Positive interactions were also observed between P. expansum and multiple fungal and bacterial species. These network analyses provide a basis for further fungal and bacterial interaction analyses for fruit disease biocontrol.

Penicillium expansum is the causal agent of blue mold decay on apple fruits and is also known to be the major producer of patulin, a mycotoxin that represents serious hazard to human health. Several mechanisms have been suggested to explain the pathogenesis of P. expansum in host plants. Secreted effector proteins are vital for the pathogenicity of many fungal pathogens through manipulating their hosts for efficient colonization. In this study, we performed a RNA-Seq analysis followed by computational prediction of effector proteins from P. expansum during infection of the host apple fruits, and a total of 212 and 268 candidate effector protein genes were identified at 6 and 9 h after inoculation (hai), respectively. One of the candidate effector protein genes was identified as a concanavalin A-like lectin/glucanase (Peclg), which was dramatically induced during the pathogen–host interaction. Targeted knockout of Peclg resulted in significant reduction in conidial production and germination relative to the wild type. Further studies showed that in addition to salt stress, the mutant was much more sensitive to SDS and Congo red, suggesting a defect in cell wall integrity. Pathogenicity assays revealed that the ΔPeclg mutant showed significant decrease in virulence and infectious growth on apple fruits. All these results suggest that Peclg is required for fungal growth, stress response, and the virulence of P. expansum. [ABSTRACT FROM AUTHOR]

Blue mold, caused by Penicillium expansum, is the most destructive fungal disease of apples and causes great losses during the post-harvest storage of the fruit. Although some apple cultivars are resistant to P. expansum, there has been little information on the molecular mechanism of resistance. In this study, differential proteomic analysis was performed on apple samples infected and uninfected with P. expansum. Parallel reaction monitoring (PRM) technology was used to target and verify the expression of candidate proteins. The label-free technique identified 343 differentially expressed proteins, which were mainly associated with defense responses, metal ion binding, stress responses, and oxidative phosphorylation. The differential expression of enzymes related to reactive oxygen species (ROS) synthesis and scavenging, the activation of defense-related metabolic pathways, and the further production of pathogenesis-related proteins (PR proteins) during P. expansum infection in apples, and direct resistance to pathogen invasion were determined. This study reveals the mechanisms of apple response at the proteomic level with 9 h of P. expansum infection. [ABSTRACT FROM AUTHOR]

Transcription factors play a key role in Penicillium expansum infection process. Although the crucial characteristics of some transcription factors of pathogenic fungi have been found, many transcription factors involved in P. expansum infections have not been explored and studied. This study aimed to screen the transcription factors of P. expansum involved in postharvest pear infections by ATAC-seq analysis and to analyze the differentially expressed peak-related genes by GO enrichment and KEGG pathway analysis. Our results found the up-regulation of differentially expressed peak-related genes involved in the MAPK signaling pathway, pentose phosphate pathway, starch and sucrose metabolism, and pentose and glucuronate interconversions. Our study especially confirmed the differential regulation of transcription factors MCM1, Ste12 and gene WSC in the MAPK signaling pathway and PG1, RPE1 in the pentose and glucuronate interconversions pathway. These transcription factors and related genes might play an essential role in pear fruit infection by P. expansum. RT-qPCR validation of twelve expressed peak-related genes in P. expansum showed that the expression levels of these twelve genes were compatible with the ATAC-Seq. Our findings might shed some light on the regulatory molecular networks consisting of transcription factors that engaged in P. expansum invasion and infection of pear fruits. [ABSTRACT FROM AUTHOR]

Coral jasmine, night blossoming jasmine, and parijat are other names for Nyctanthes arbor-tristis. In the current study, an effort was made to check into Nyctanthes arbor-tristis antifungal characteristics. The aforementioned plants' leaves were collected for the study and turned into a basic medication powder extract. The gram-negative bacterium Pseudomonas aeruginosa was utilised to carry out the antibacterial activities. The Penicillium expansum was utilised to carry out the antifungal activities. The disc diffusion method was utilised to test antibacterial activity. Test material extracts in ethanol solvent exhibited strong antibacterial activity against harmful microorganisms. The data revealed that Nyctanthes arbor-tristis ethanol extract displays maximum antibacterial activity as reference compound. [ABSTRACT FROM AUTHOR]

Penicillium expansum is the main cause of apple rot. Besides, it can also produce mycotoxin patulin (PAT). Therefore, the search for substances that can inhibit the activity and toxigenicity of P. expansum has become a hot research topic. This study investigates the inhibitory effects of fengycin on patulin production in P. expansum. P. expansum was cultured under different environments with different concentrations of fengycin. The patulin content produced per unit weight of P. expansum mycelium was detected and determined by high pressure liquid chromatography (HPLC). Synergy brands (SYBR) GreenI Real-time PCR was used to detect the expression levels of 6-methylsalicylic acid synthase (6-MSAS) and isoepoxydon dehydrogenase (IDH), which were the key genes of producing patulin of P. expansum mycelium, in the conditions treated by fengycin and untreated. After fengycin treatments, not only the patulin content in every unit weight of P. expansum mycelium but also the expression level of 6-MSAS decreased significantly. The expression level of 6-MSAS of treatment was 0.11 folds of control. However, the expression level of IDH treated by fengycin decreased slightly. Fengycin could inhibit the P. expansum from producing patulin by downregulating the expression of key synthetic genes 6-MSAS.

Penicillium expansum causes blue mold in fruit, leading to the accumulation of patulin, a harmful toxin. Current detection methods for patulin are costly and complex, highlighting the need for a simplified approach. This study investigates the impact of P. expansum on 'Golden Delicious' and 'Fuji' apples, focusing on significant changes in lesion characteristics and fruit properties. Correlation analysis revealed strong positive associations between patulin content and lesion diameter, lesion depth, and fruit weight loss, while negative correlations were observed with apple firmness and flesh firmness. Of the four machine learning models used - Back Propagation Neural Network (BPNN), Random Forest (RF), Extreme Gradient Boosting (XGBoost) and Gradient Boosting Regression Tree (GBRT) - all showed good predictive performance without overfitting the data. BPNN outperformed the others in accurately predicting patulin accumulation (Golden Delicious: RMSE=0.72, MAE=0.217, R²=0.982; Fuji: RMSE=0.289, MAE=0.08, R²=0.994). Key features influencing patulin accumulation, identified using SHapley Additive exPlanation (SHAP) measures, included lesion diameter, lesion depth, and fruit weight loss. This research highlights the potential of machine learning to predict patulin accumulation based on these critical factors, providing a simplified detection method for postharvest fruit quality management. • The BPNN model excels at accurately predicting patulin levels in apples. • SHAP measures identify key characteristics that influence patulin accumulation. • Simplified patulin detection using lesion characteristics and fruit characteristics. [ABSTRACT FROM AUTHOR]

Blue mold, a postharvest disease of pome fruits, is caused by the filamentous fungus Penicillium expansum. In addition to the economic losses caused by P. expansum, food safety can be compromised, as this pathogen is mycotoxigenic. In this study, forward and reverse genetic approaches were used to identify genes involved in blue mold infection in apple fruits. For this, we generated a random T-DNA insertional mutant library. A total of 448 transformants were generated and screened for the reduced decay phenotype on apples. Of these mutants, six (T-193, T-275, T-434, T-588, T-625, and T-711) were selected for continued studies and five unique genes were identified of interest. In addition, two deletion mutants (Δt-625 and Δt-588) and a knockdown strain (t-434KD) were generated for three loci. Data show that the ∆t-588 mutant phenocopied the T-DNA insertion mutant and had virulence penalties during apple fruit decay. We hypothesize that this locus encodes a glyoxalase due to bioinformatic predictions, thus contributing to reduced colony diameter when grown in methylglyoxal (MG). This work presents novel members of signaling networks and additional genetic factors that regulate fungal virulence in the blue mold fungus during apple fruit decay.

Penicillium expansum is the most popular post-harvest pathogen and causes blue mold disease in pome fruit and leads to significant economic losses worldwide every year. However, the fundamental regulation mechanisms of growth in P. expansum are unclear. Recently, non-coding RNAs (ncRNAs) have attracted more attention due to critical roles in normalizing gene expression and maintaining cellular genotypes in organisms. However, the research related to ncRNAs in P. expansum have not been reported. Therefore, to provide an overview of ncRNAs on composition, distribution, expression changes, and potential targets in the growth process, a comparative transcriptomic analysis was performed on spores and mycelia of P. expansum in the present study. A total of 2595 novel mRNAs, 3362 long non-coding RNAs (lncRNAs), 10 novel microRNAs (miRNAs), 86 novel small interfering RNAs (siRNAs), and 11,238 circular RNAs (circRNAs) were predicted and quantified. Of these, 1482 novel mRNAs, 5987 known mRNAs, 2047 lncRNAs, 40 miRNAs, 38 novel siRNAs, and 9235 circRNAs were differentially expressed (DE) in response to the different development stages. Afterward, the involved functions and pathways of DE RNAs were revealed via Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) database enrichment analysis. The interaction networks between mRNAs, lncRNAs, and miRNAs were also predicted based on their correlation coefficient of expression profiles. Among them, it was found that miR168 family members may play important roles in fungal growth due to their central location in the network. These findings will contribute to a better understanding on regulation machinery at the RNA level on fungal growth and provide a theoretical basis to develop novel control strategies against P. expansum.

β-1,3-glucanase plays an important role in the biodegradation, reconstruction, and development of β-1,3-glucan. An endo-β-1,3-glucanase which was encoded by PeBgl1 was expressed, purified and characterized from Penicillium expansum for the first time. The PeBgl1 gene was amplified and transformed into the competent cells of E. coli Rosetta strain with the help of the pET-30a cloning vector. The recombinant protein PeBgl1 was expressed successfully at the induction conditions of 0.8 mmol/L IPTG at 16 °C for 16 h and then was purified by nickel ion affinity chromatography. The optimum reaction temperature of PeBgl1 was 55 °C and it had maximal activity at pH 6.0 according to the enzymatic analysis. Na2HPO4-NaH2PO4 buffer (pH 6.0) and NaCl have inhibitory and enhancing effects on the enzyme activities, respectively. SDS, TritonX-100 and some metal ions (Mg2+, Ca2+, Ba2+, Cu2+, and Zn2+) have an inhibitory effect on the enzyme activity. The results showed that PeBgl1 protein has good enzyme activity at 50–60 °C and at pH 5.0–9.0, and it is not a metal dependent enzyme, which makes it robust for storage and transportation, ultimately holding great promise in green biotechnology and biorefining.

Methyl jasmonate (MeJA) is a plant-signalling molecule that plays significant roles in stress reactions and defence responses. The goal of this study was to characterize the effects of exogenous MeJA application on the resistance of postharvest pear fruit to blue mould rot caused by Penicillium expansum and investigate the mechanism underlying the observed effects of MeJA application. MeJA treatment effectively reduced the lesion diameter of blue mould rot in pear fruit. Furthermore, MeJA significantly enhanced the activities of antioxidant and defence-related enzymes, such as polyphenol oxidase (PPO), superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), β-1,3 glucanase (GLU) and chitinase (CHI); total phenol content also increased, and membrane lipid peroxidation decreased. MeJA treatment promoted the expression of PpPPO, Cu-ZnSOD, PpPOD, PpCAT, PpCHI and PpGLU. Overall, this experiment suggested that MeJA-induced pear fruit resistance against blue mould rot may be related to the enhanced activities of defence enzymes and gene expression.

ABSTRACT Fruit blue mold disease and patulin contamination caused by Penicillium expansum lead to huge economic losses and food safety concerns worldwide. Many genes have been proven to be involved in the regulation of pathogenic and toxigenic processes of P. expansum. Histone H3 lysine 4 (H3K4) methylation is well recognized for its association with chromatin regulation and gene transcription. However, it is not clear whether H3K4 methylation is related to infection and patulin biosynthesis in Penicillium. Here, we characterized PeSet1, which is responsible for H3K4me1/me2/me3 in P. expansum. The deletion of PeSet1 caused severe defects in hyphal growth, conidiation, colonization, patulin biosynthesis, and stress responses. Moreover, we demonstrated that PeSet1 is involved in the regulation of patulin biosynthesis by mediating the expression of patulin cluster genes and crucial global regulatory factors. Likewise, PeSet1 positively regulated key genes in β-1,3-glucan biosynthesis and the reactive oxygen species scavenging process to modulate cell wall integrity and oxidative stress responses, respectively. Collectively, we have proven for the first time the function of Set1 in patulin biosynthesis and the crucial role of Set1 in colonization and stress responses in P. expansum. IMPORTANCE Penicillium expansum is one of the most important plant fungal pathogens, which not only causes blue mold rot in various fruits, leading to huge decay losses, but also produces mycotoxin patulin, posing a threat to human health. Both pathogenesis and patulin biosynthesis in P. expansum are regulated by complex and sophisticated networks. We focused on the epigenetic modification and identified a conserved histone H3K4 methyltransferase PeSet1 in P. expansum. Our work revealed the important role of PeSet1 in growth, development, colonization, patulin production, and stress responses of P. expansum. In particular, we originally described the regulation of Set1 on patulin biosynthetic pathway. These findings will provide new targets for the prevention and control of blue mold disease and patulin contamination.

ABSTRACT Hydrophobins are small amphipathic surface proteins found exclusively in fungi. In filamentous ascomycetes, one conserved role of a subset of hydrophobins is their requirement for spore dispersal. Other contributions of these proteins to fungal biology are less clear and vary across genera. To determine the functions of hydrophobins in the biology and virulence of this fungus, we created seven single mutants and a septuple-deletion mutant (Δsep) of the entire putative P. expansum hydrophobin gene family. One spore hydrophobin, HfbA, shared 72.56% sequence identity to the Aspergillus fumigatus spore hydrophobin RodA and was required for efficient spore dispersion in P. expansum. The Δsep mutant was likewise reduced in spore dispersal, hypothesized to be due to the aberrant shape and clumping of the Δsep conidia and conidiophores. Additionally, the Δsep mutant presented several differences in physiological traits, including decreased survival in extreme cold temperatures and increased production of several toxic secondary metabolites. Most striking was the unexpected fitness advantage that the Δsep strain displayed in competitive passaging with the wild-type strain on host apple where the mutant significantly increased in percentage of the colonizing population. This work uncovers potential ecological trade-offs of hydrophobin presence in filamentous fungi. IMPORTANCE Hydrophobins are amphipathic secreted proteins uniquely found in filamentous fungi. These proteins self-assemble and constitute the outer most layer of fungal surfaces thus mediating multiple aspects of fungal interactions with their environments. Hydrophobins facilitate spore dispersal, yet a full understanding of the function and need for multiple hydrophobins in fungal species remains elusive. To address the role of this protein family in Penicillium expansum, the causative agent of blue mold disease in pome fruit, all seven putative hydrophobin genes were deleted and the mutant assessed for numerous physiological traits and virulence on fruit. Despite showing a decrease in spore dispersal, the septuple-deletion mutant was more fit than the wild type in competitive pathogenicity tests on apple. Our findings suggest this gene family illustrates a functional trade-off between dispersal and host colonization in P. expansum.

Salicylic acid (SA) is a natural inducer of disease resistance in fruit, but its application in the food industry is limited due to low water solubility. Here, SA was encapsulated in β-cyclodextrin (β-CD) via the host–guest inclusion complexation method, and the efficacy of SA microcapsules (SAM) against blue mold caused by Penicillium expansum in postharvest apple fruit was elucidated. It was observed that SAM was the most effective in inhibiting the mycelial growth of P. expansum in vitro. SAM was also superior to SA for control of blue mold under in vivo conditions. Enzyme activity analysis revealed that both SA and SAM enhanced the activities of superoxide dismutase (SOD) and phenylalanine ammonia lyase (PAL) in apple fruit, whereas SAM led to higher SOD activities than SA. Total phenolic contents in the SAM group were higher than those in the SA group at the early stage of storage. SAM also improved fruit quality by retarding firmness loss and maintaining higher total soluble solids (TSS) contents. These findings indicate that microcapsules can serve as a promising formulation to load SA for increasing P. expansum inhibition activity and improving quality attributes in apple fruit. [ABSTRACT FROM AUTHOR]

Penicillium expansum is a necrotrophic pathogen, which actively kills host cells and obtains nutrients from dead cells to achieve infection. However, few reports have elucidated the differential levels of carbon and nitrogen sources over increasing distances of the leading edge in fungal colonized fruit tissues during colonization. Our results showed that the highest consumption of sucrose and fructose, as well as the accumulation of glucose, were found in the decayed region of P. expansum-colonized 'Delicious' apple fruit compared with the healthy region at the leading edge and the healthy region 6 mm away from the leading edge. As nitrogen sources, the contents of methionine, glutamate, leucine, valine, isoleucine and serine were the lowest in the decayed region compared with the healthy regions during colonization. In addition, the titratable acidity, oxalic acid, citric acid, succinic acid and malic acid showed the highest accumulation in the decayed region compared with the healthy regions. P. expansum colonization induced the accumulation of saturated fatty acids in the decayed region, while the level of unsaturated fatty acids was the lowest. These changes were not observed in the healthy regions. These results indicated that P. expansum kills cells in advance of its colonization in order to obtain the nutrients of the apple tissue from the distal leading tissue of the colonized apple. It is understood that more carbon and nitrogen sources are required for fungal colonization, and a stronger defense response against colonization occurred in the fruit, causing the transit of nutrients from the distal tissue to the infected sites. [ABSTRACT FROM AUTHOR]

Two new compounds, including one meroterpenoid (1) and a polyketide derivative (2), along with six compounds (3 − 8), were isolated from the rice solid fermentation of Penicillium expansum GY618. The structures of these new compounds were elucidated through interpretations of spectroscopic data and highresolution electrospray ionization mass spectrometry. The absolute configurations of all new compounds were unambiguously established through the optical rotation or calculation of the ECD spectrum. All isolated compounds were evaluated for their antibacterial and antitumor activities. Compound 6 exhibited weak antitumor activity. [Display omitted] • One new meroterpenoid and a new polyketide derivative were isolated. • The absolute configuration of all new compounds was unambiguously established. • Compound 6 showed weak antitumor activity. [ABSTRACT FROM AUTHOR]

Apples (Malus domestica) are one of the most consumed fruits globally. It is a relevant crop in Argentina and Spain, and one of the main fruits for export and industrialization in these countries. Quality control of apples, fundamentally in the postharvest stage, is critical to prevent fungal diseases. The blue mould, caused by Penicillium expansum , is responsible for great economic losses due to the deterioration of the fruit and mycotoxin production. Many studies have characterized this pathogen; however, little is known about the differences between populations from distant geographical origins. The objective of the present study was to characterize two P. expansum populations, from Argentina and Spain, through morphological, metabolomic and molecular approaches, and to evaluate the existence of differences related to their geographical source. A total of 103 isolates, 53 from Argentina and 50 from Spain were studied. Their morphological features were consistent with the species description. The secondary metabolite profiles revealed low chemical diversity. All 103 isolates shared the production of 13 compounds, namely andrastins, aurantioclavine, chaetoglobosins, communesins, expansolides, roquefortine C and patulin. Penostatins and citrinin were produced by 102 and 101 isolates, respectively. A region of the β-tubulin gene was selected to analyse the diversity of the P. expansum isolates. No substantial differences were observed between isolates of different geographical origins through morphology, patulin accumulation, secondary metabolite profiles and phylogenetic analysis. However, the analysis of polymorphisms revealed 29 haplotypes with a relative separation between isolates of both populations; 13 haplotypes contained Argentinean isolates, while Spanish isolates were separated into 16 haplotypes. The diversity indices of Shannon (H'= 2.075; H'= 2.402) and Simpson (Si D = 0.850; Si D = 0.895) for isolates from Argentina and Spain, respectively, indicated that the diversity of P. expansum is greater in Spain than in Argentina. This distribution could be explained both by the existence of haplotype exchange between both countries, with the ancestral haplotypes originating in Spain, and the subsequent adaptation to the environmental conditions or apples varieties grown in each region. • Penicillium expansum populations from Argentinean and Spanish apples were compared. • P. expansum populations showed low secondary metabolite diversity. • Phylogenetic analyses did not allow establishing evolutionary relationships. • Relative separation was revealed by analysis of polymorphisms in the β-tub fragment. • A significant geographical genetic structure was found in the populations. [ABSTRACT FROM AUTHOR]

Penicillium expansum (P. expansum), a widespread fungal pathogen, causes serious economic loss and public health concerns. The aim of this research is to investigate the antifungal effect of Kluyveromyces marxianus YG-4 (K. marxianus YG-4) against P. expansum and possible mechanism. The results showed that competition for nutrients and space, as well as the release of volatile organic compounds (VOCs), are the antifungal mechanisms. Citronellol may be the antifungal component of K. marxianus YG-4 VOCs based on GC-MS analysis. Further experiments had shown that citronellol inhibited the growth of P. expansum LPH9 by damaging the cell structure, disrupting the redox system, reducing antioxidant enzyme activity, and causing oxidative damage. K. marxianus YG-4, K. marxianus YG-4 VOCs and citronellol can effectively inhibit the spore germination of P. expansum on apples. The above results indicated that K. marxianus YG-4 had strong biocontrol activity and can be used as an excellent candidate strain for fruit preservation., Competing Interests: Declaration of competing interest The authors declare no conflicts of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Penicillium expansum is the major fungus that causes blue mold and produces patulin, threatening human health. Due to health and environmental pollution concerns, chitosan (CS) has attracted more and more attention as a safer alternative to synthetic fungicides for the control of blue mold. In the present study, four different benzimidazole groups were introduced onto CS by the acylation reaction to obtain benzimidazole-based chitosan derivatives (R1b-R4b). After being well-characterized with Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-vis spectra), and nuclear magnetic resonance (NMR), their antifungal activities against P. expansum were screened. Results showed that the inhibitory effects of chitosan derivatives against the pathogen were significantly correlated with chitosan derivatives' concentration and their structures. R4b was shown as optimum with good solubility and antifungal activity with a minimum inhibitory concentration (MIC) value of 0.5 mg/mL and a minimum fungicidal concentration (MFC) value of 2.0 mg/mL. The remarkable antifungal efficiency of R4b against P. expansum was further demonstrated in terms of spore germination, mycelial growth, patulin production, and the preliminary antifungal mechanism. R4b exhibited significant inhibition of patulin production, while its antifungal mechanism was revealed by destroying cell membrane integrity and inducing membrane depolarization. Furthermore, R4b treatment could significantly reduce the incidence of blue mold rot in apple fruit, and the MTT assay showed the nontoxicity of R4b against Raw 264.7, HBZY-1, and Caco-2 cells. Altogether, these results indicate that it is promising to be used as a fruit preservative in the future.

Antioxidant and antifungal activities of three essential oils (EOs): Melaleuca ericifolia Smith (rosalina; REO), Melaleuca quinquenervia (niaouli; NEO) and Abies alba (fir; FEO) were determined. The antioxidant capacity was investigated by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, and the disc diffusion method was applied to evaluate their antifungal efficacy (in four concentrations 62.5 μL/L, 125 μL/L, 250 μL/L, 500 μL/L used) against Penicillium (P.) expansum microscopic filamentous fungus isolated from bread samples. From the findings it can be clearly evident that antioxidant activities of the EOs were very weak with values ranging from 25.81 ± 7.8 TEAC (6.2 ± 1.4%; FEO) to 162.0 ± 2.1 TEAC (15.9 ± 0.4%; NEO). Regarding antifungal properties, our results revealed that the effects of the EOs on P. expansum growth inhibition were dose-dependent, and they were proportionally increased with increasing EOs concentrations. Detected inhibition zones ranged from 0.00 ± 0.00 mm (for all EOs at 62.5 μL/L) to 11.67 ± 1.15 mm (for REO at 500 μL/L). In conclusion, all analyzed EOs possess promising in vitro antifungal activity (despite their weak antioxidant capacity) suggesting their use as a promising natural preservative in the food industry.

Penicillium expansum is a main producer of patulin that causes severe postharvest decay and food safety issues in the fruit industry. Development, pathogenicity, and patulin production of P. expansum are strongly influenced by the PacC-pH signaling pathway. Global transcription factor PacC regulates various fungal biological processes through a complicated molecular network. In the present study, three Ena family genes (PeEnas), PeEnaA, PeEnaB, and PeEnaC, as important downstream targets of PePacC, were identified in P. expansum. Deletion of PeEnaA, PeEnaB, and PeEnaC showed little effect on mycelial growth under alkaline or high salinity conditions, but double and triple deletion of these genes impaired the virulence of P. expansum on apple fruit. Notably, patulin biosynthesis of P. expansum was distinctly inhibited in the deletion mutants of PeEnas. PeEnas regulated expressions of the patulin gene cluster, AP1, CreA, Sge1, and Hog1 at the transcriptional level and played roles in maintaining membrane potential. Overexpression of PeEnaC in ΔPePacC restored the patulin production defect of ΔPePacC. Our results indicated that, as downstream targets of PePacC, the PeEna family proteins play a crucial role in patulin biosynthesis in P. expansum.