Several secondary metabolite gene clusters in the genomes of ten Penicillium spp. raise the risk of multiple mycotoxin occurrence in chestnuts.

Penicillium spp. produce a great variety of secondary metabolites, including several mycotoxins, on food substrates. Chestnuts represent a favorable substrate for Penicillium spp. development. In this study, the genomes of ten Penicillium species, virulent on chestnuts, were sequenced and annotated: P. bialowiezense. P. pancosmium, P. manginii, P. discolor, P. crustosum, P. palitans, P. viridicatum, P. glandicola, P. taurinense and P. terrarumae. Assembly size ranges from 27.5 to 36.8 Mb and the number of encoded genes ranges from 9,867 to 12,520. The total number of predicted biosynthetic gene clusters (BGCs) in the ten species is 551. The most represented families of BGCs are non ribosomal peptide synthase (191) and polyketide synthase (175), followed by terpene synthases (87). Genome-wide collections of gene phylogenies (phylomes) were reconstructed for each of the newly sequenced Penicillium species allowing for the prediction of orthologous relationships among our species, as well as other 20 annotated Penicillium species available in the public domain. We investigated in silico the presence of BGCs for 10 secondary metabolites, including 5 mycotoxins, whose production was validated in vivo through chemical analyses. Among the clusters present in this set of species we found andrastin A and its related cluster atlantinone A, mycophenolic acid, patulin, penitrem A and the cluster responsible for the synthesis of roquefortine C/glandicoline A/glandicoline B/meleagrin. We confirmed the presence of these clusters in several of the Penicillium species conforming our dataset and verified their capacity to synthesize them in a chestnut-based medium with chemical analysis. Interestingly, we identified mycotoxin clusters in some species for the first time, such as the andrastin A cluster in P. flavigenum and P. taurinense, and the roquefortine C cluster in P. nalgiovense and P. taurinense. Chestnuts proved to be an optimal substrate for species of Penicillium with different mycotoxigenic potential, opening the door to risks related to the occurrence of multiple mycotoxins in the same food matrix.

Effects of temperature, pH, and relative humidity on the growth of Penicillium paneum OM1 isolated from pears and its patulin production.

Patulin is a mycotoxin produced by several species of Penicillium sp., Aspergillus sp., and Byssochlamys sp. on apples and pears. Most studies have been focused on Penicillium expansum, a common postharvest pathogen, but little is known about the characteristics of Penicillium paneum. In the present study, we evaluated the effects of temperature, pH, and relative humidity (RH) on the growth of P. paneum OM1, which was isolated from pears, and its patulin production. The fungal strain showed the highest growth rate at 25 °C and pH 4.5 on pear puree agar medium (PPAM) under 97 % RH, while it produced the highest amount of patulin at 20 °C and pH 4.5 on PPAM under 97 % RH. Moreover, RT-qPCR analysis of relative expression levels of 5 patulin biosynthetic genes (patA, patE, patK, patL, and patN) in P. paneum OM1 exhibited that the expression of the 4 patulin biosynthetic genes except patL was up-regulated in YES medium (patulin conducive), while it was not in PDB medium (patulin non-conducive). Our data demonstrated that the 3 major environmental parameters had significant impact on the growth of P. paneum OM1 and its patulin production. These results could be exploited to prevent patulin contamination by P. paneum OM1 during pear storage.

Involvement of multiple forms of cell death in patulin-induced toxicities.

Patulin (PAT) is the most common mycotoxin found in moldy fruits and their derived products, and is reported to cause diverse toxic effects, including hepatotoxicity, nephrotoxicity, cardiotoxicity, neurotoxicity, immunotoxicity, gastrointestinal toxicity and dermal toxicity. The cell death induction by PAT is suggested to be a key cellular mechanism involved in PAT-induced toxicities. Accumulating evidence indicates that the multiple forms of cell death are induced in response to PAT exposure, including apoptosis, autophagic cell death, pyroptosis and ferroptosis. Mechanistically, the cell death induction by PAT is associated the oxidative stress induction via reducing the antioxidant capacity or inducing pro-oxidant NADPH oxidase, the activation of mitochondrial pathway via regulating BCL-2 family proteins, the disruption of iron metabolism through ferritinophagy-mediated ferritin degradation, and the induction of the NOD-like receptor (NLR) family pyrin domain containing 3 (NLRP3) inflammasome/caspase-1/gasdermin D (GSDMD) pathway. In this review article, we summarize the present understanding of the cell death induction by PAT, discuss the potential signaling pathways underlying PAT-induced cell death, and propose the issues that need to be addressed to promote the development of cell death-based approach to counteract PAT-induced toxicities.

Detoxification of Mycotoxin Patulin by the Yeast Kluyveromyces marxianus YG-4 in Apple Juice.

Patulin (PAT) is a mycotoxin produced by Penicillium species, which often contaminates fruit and fruit-derived products, posing a threat to human health and food safety. This work aims to investigate the detoxification of PAT by Kluyveromyces marxianus YG-4 (K. marxianus YG-4) and its application in apple juice. The results revealed that the detoxification effect of K. marxianus YG-4 on PAT includes adsorption and degradation. The adsorption binding sites were polysaccharides, proteins, and some lipids on the cell wall of K. marxianus YG-4, and the adsorption groups were hydroxyl groups, amino acid side chains, carboxyl groups, and ester groups, which were combined through strong forces (ion interactions, electrostatic interactions, and hydrogen bonding) and not easily eluted. The degradation active substance was an intracellular enzyme, and the degradation product was desoxypatulinic acid (DPA) without cytotoxicity. K. marxianus YG-4 can also effectively adsorb and degrade PAT in apple juice. The contents of organic acids and polyphenols significantly increased after detoxification, significantly improving the quality of apple juice. The detoxification ability of K. marxianus YG-4 toward PAT would be a novel approach for the elimination of PAT contamination.

Patulin alters alpha-adrenergic receptor signalling and induces epigenetic modifications in the kidneys of C57BL/6 mice.

Patulin (PAT) is a food-borne mycotoxin produced by Penicillium and Byssochlamys species. It is widely known for its mutagenic, carcinogenic, and genotoxic effects and has been associated with kidney injury; however, the mechanism of toxicity remains unclear. To address this gap, we conducted a study to explore the changes in α-adrenergic receptor signalling pathways and epigenetic modifications induced by PAT in the kidneys of C57BL/6 mice during acute (1 day) and prolonged (10 days) exposure. The mice (20-22 g) were orally administered PAT (2.5 mg/kg; at 1 and 10 days), and post-treatment, the kidneys were harvested, homogenised and extracted for RNA, DNA, and protein. The relative gene expression of the α-adrenergic receptors (ADRA1, ADRA2A, ADRA2B) and associated signalling pathways (MAPK, MAPK14, ERK, PI3K, and AKT) was assessed by qPCR. The protein expression of ERK1/2 and MAPK was determined by western blot. The impact of PAT on DNA methylation was evaluated by quantifying global DNA methylation; qPCR was used to determine gene expression levels of DNA methyltransferases (DNMT1, DNMT3A, and DNMT3B) and demethylase (MBD2). PAT downregulated the expression of ADRA1, ADRA2A, ADRA2B, PI3K, and AKT and upregulated ERK1/2 and MAPK protein expression. Furthermore, PAT induced alterations in DNA methylation patterns by upregulating DNMT1 and MBD2 expressions and downregulating DNMT3A and DNMT3B expressions, resulting in global DNA hypomethylation. In conclusion, PAT disrupts α-1 and α-2 adrenergic receptor signalling pathways and induces epigenetic modifications, that can lead to kidney injury.

Integrated transcriptomics and metabolomics reveal the mechanism of intestinal damage upon acute patulin exposure in mice.

Mycotoxin contamination has become a major food safety issue and greatly threatens human and animal health. Patulin (PAT), a common mycotoxin in the environment, is exposed through the food chain and damages the gastrointestinal tract. However, its mechanism of enterotoxicity at the genetic and metabolic levels remains to be elucidated. Herein, the intestinal histopathological and biochemical indices, transcriptome, and metabolome of C57BL/6 J mice exposed to different doses of PAT were successively assessed, as well as the toxicokinetics of PAT in vivo. The results showed that acute PAT exposure induced damaged villi and crypts, reduced mucus secretion, decreased SOD and GSH-Px activities, and enhanced MPO activity in the small intestine and mild damage in the colon. At the transcriptional level, the genes affected by PAT were dose-dependently altered in the small intestine and fluctuated in the colon. PAT primarily affected inflammation-related signaling pathways and oxidative phosphorylation in the small intestine and immune responses in the colon. At the metabolic level, amino acids decreased, and extensive lipids accumulated in the small intestine and colon. Seven metabolic pathways were jointly affected by PAT in two intestinal sites. Moreover, changes in PAT products and GST activity were detected in the small intestinal tissue but not in the colonic tissue, explaining the different damage degrees of the two sites. Finally, the integrated results collectively explained the toxicological mechanism of PAT, which damaged the small intestine directly and the colon indirectly. These results paint a clear panorama of intestinal changes after PAT exposure and provide valuable information on the exposure risk and toxic mechanism of PAT.

Patulin Biodegradation Mechanism Study in Pichia guilliermondii S15-8 Based on PgSDR-A5D9S1.

Patulin contamination has become a bottleneck problem in the safe production of fruit products, although biodegradation technology shows potential application value in patulin control. In the present study, the patulin biodegradation mechanism in a probiotic yeast, Pichia guilliermondii S15-8, was investigated. Firstly, the short-chain dehydrogenase PgSDR encoded by gene A5D9S1 was identified as a patulin degradation enzyme, through RNA sequencing and verification by qRT-PCR. Subsequently, the exogenous expression system of the degradation protein PgSDR-A5D9S1 in E. coli was successfully constructed and demonstrated a more significant patulin tolerance and degradation ability. Furthermore, the structure of PgSDR-A5D9S1 and its active binding sites with patulin were predicted via molecular docking analysis. In addition, the heat-excited protein HSF1 was predicted as the transcription factor regulating the patulin degradation protein PgSDR-A5D9S1, which may provide clues for the further analysis of the molecular regulation mechanism of patulin degradation. This study provides a theoretical basis and technical support for the industrial application of biodegradable functional strains.

A novel g-C3N4-SH@konjac glucomannan composite aerogel for patulin removal from apple juice and its photocatalytic regeneration.

Patulin (PAT) is a hazardous mycotoxin frequently occurs in fruit industry. A reusable g-C3N4-SH@KG composite aerogel for PAT removal in a novel "dark adsorption-light regeneration" mode was prepared by thiol(-SH) functionalization and konjac glucomannan (KG) immobilization. The g-C3N4-SH@KG was characterized by SEM, FT-IR, XPS and UV-Vis DRS, and its PAT adsorption and photocatalytic regeneration behaviors and mechanisms were investigated. The g-C3N4-SH@KG exhibited good regeneration performance, maintaining 83% of PAT initial adsorption capacity (0.92 mg/g) after 5 "adsorption-regeneration" cycles. The adsorption process was endothermic and spontaneous. •OH and h+ generated by photocatalysis were the main substances that degraded PAT into two products and regenerated -SH. The g-C3N4-SH@KG could effectively remove PAT without negative impact on juice quality. The study provided a new strategy for the regeneration of thiol-functionalized PAT adsorbents, and a new idea for the application of non-selective photocatalysis in the control of food contaminations.

Immunosuppressive effects of the mycotoxin patulin in macrophages.

Patulin (PAT) is a fungi-derived secondary metabolite produced by numerous fungal species, especially within Aspergillus, Byssochlamys, and Penicillium genera, amongst which P. expansum is the foremost producer. Similar to other fungi-derived metabolites, PAT has been shown to have diverse biological features. Initially, PAT was used as an effective antimicrobial agent against Gram-negative and Gram-positive bacteria. Then, PAT has been shown to possess immunosuppressive properties encompassing humoral and cellular immune response, immune cell function and activation, phagocytosis, nitric oxide and reactive oxygen species production, cytokine release, and nuclear factor-κB and mitogen-activated protein kinases activation. Macrophages are a heterogeneous population of immune cells widely distributed throughout organs and connective tissue. The chief function of macrophages is to engulf and destroy foreign bodies through phagocytosis; this ability was fundamental to his discovery. However, macrophages play other well-established roles in immunity. Thus, considering the central role of macrophages in the immune response, we review the immunosuppressive effects of PAT in macrophages and provide the possible mechanisms of action.

Study of cytotoxicity in neuroblastoma cell line exposed to patulin and citrinin.

Mycotoxins can be found in food and feed storage as well as in several kinds of foodstuff and are capable of harming mammals and some of them even in small doses. This study investigated on the undifferentiated neuronal cell line SH-SY5Y the effects of two mycotoxins: patulin (PAT) and citrinin (CTN), which are predominantly produced by fungi species Penicillium and Aspergillus. Here, the individual and combined cytotoxicity of PAT and CTN was investigated using the cytotoxic assay MTT. Our findings indicate that after 24 h of treatment, the IC50 value for PAT is 2.01 µM, which decreases at 1.5 µM after 48 h. In contrast, CTN did not attain an IC50 value at the tested concentration. Therefore, we found PAT to be the more toxic compared to CTN. However, the combined treatment suggests an additive toxic effect. With 2,7-dichlorodihydrofluorescin diacetate (DCFH-DA) DCFH-DA assay, ROS generation was demonstrated after CTN treatment, but PAT showed only small changes. The mixture presented a very constant behavior over time. Finally, the median-effect/combination index (CI-) isobologram equation demonstrated an additive effect after 24 h, but an antagonistic effect after 48 h for the interaction of the two mycotoxins.

Portable self-powered electrochemical aptasensing platform for ratiometric detection of mycotoxins based on multichannel photofuel cell.

Self-powered electrochemical sensors based on photofuel cells have attracted considerable research interest because their unique advantage of not requiring an external electric source, but their application in portable and multiplexed targets assay is limited by the inherent mechanism. In this work, a portable self-powered sensor constructed with multichannel photofuel cells was developed for the ratiometric detection of mycotoxins, namely ochratoxin A (OTA) and patulin (PAT). The spatially resolved CdS/Bi2S3-modified photoanodes and a shared Prussian Blue cathode were integrated on an etched indium-tin oxide slide to fabricate the multichannel photofuel cell. The aptamers of OTA and PAT were covalently bonded to individual photoanode regions to build sensitive interfaces, and the specific recognition of analytes impaired the output performance of constructed PFC. Accordingly, ratiometric sensing of OTA and PAT was achieved by utilizing the output performance of a control PFC as a reference signal. This approach effectively eliminates the impact of light intensity on the accuracy of the detection. Under the optimal conditions, the proposed sensing chip exhibited linear ranges of 2.0-1000 nM and 5.0-500 nM for OTA and PAT, respectively. The detection limits (3 S/N) were determined to be 0.25 nM for OTA and 0.27 nM for PAT. The developed ratiometric sensing method demonstrated good selectivity and stability in the simultaneous detection of OTA and PAT. It was successfully utilized for the analysis of OTA and PAT real samples. This work provides a new perspective for construction of portable and ratiometric self-powered sensing platform.

A Redox Mediator-Free Highly Selective and Sensitive Electrochemical Aptasensor for Patulin Mycotoxin Detection in Apple Juice Using Ni-NiO Pseudocapacitive Nanomaterials.

Pseudocapacitive nanomaterials have recently gained significant attention in electrochemical biosensors due to their rapid response, long cycle life, high surface area, biomolecule compatibility, and superior energy storage capabilities. In our study, we introduce the potential of using Ni-NiO nanofilm's pseudocapacitive traits as transducer signals in electrochemical aptasensors. Capitalizing on the innate affinity between histidine and nickel, we immobilized histidine-tagged streptavidin (HTS) onto Ni-NiO-modified electrodes. Additionally, we employed a biolayer interferometry-based SELEX to generate biotinylated patulin aptamers. These aptamers, when placed on Ni-NiO-HTS surfaces, make a suitable biosensing platform for rapid patulin mycotoxin detection in apple juice using electrochemical amperometry in microseconds. The novelty lies in optimizing pseudocapacitive nanomaterials structurally and electrochemically, offering the potential for redox mediator-free electrochemical aptasensors. Proof-of-concept is conducted by applying this surface for the ultrasensitive detection of a model analyte, patulin mycotoxin. The aptamer-functionalized bioelectrode showed an excellent linear response (10-106 fg/mL) and an impressive detection limit (1.65 fg/mL, +3σ of blank signal). Furthermore, reproducibility tests yielded a low relative standard deviation of 0.51%, indicating the good performance of the developed biosensor. Real sample analysis in freshly prepared apple juice revealed no significant difference (P < 0.05) in current intensity between spiked and real samples. The sensor interface maintained excellent stability for up to 2 weeks (signal retention 96.45%). The excellent selectivity, stability, and sensitivity of the electrochemical aptasensor exemplify the potential for using nickel-based pseudocapacitive nanomaterials for a wide variety of electrochemical sensing applications.

Determination and analysis of patulin in apples, hawthorns, and their products by high-performance liquid chromatography.

This study aimed to establish a high-performance liquid chromatography (HPLC) method to investigate the residues of patulin in apples, hawthorns, and their products. A total of 400 samples were collected from online shopping plats and supermarkets in China, including apples (n = 50), hawthorns (n = 50), and their products (apple juice, apple puree, apple jam, hawthorn juice, hawthorn chips, and hawthorn rolls, n = 300). In this experiment, this method had good linearity and a recovery of 82.3-94.4% for patulin. The limit of detection (LOD) was 0.2 µg/kg for liquid samples, while it was 0.3 µg/kg for solid and semi-fluid samples. The frequencies of patulin were 79.8% in 400 samples, and the patulin concentration is from 0.6 to 126.0 µg/kg. Two samples (0.5%) for patulin exceeded the regulatory limit (50 µg/kg) in 400 samples. The frequencies of patulin in kinds of samples were 32.0-98.0% (p < 0.05), and the percentage of samples exceeding the limit was not more than 2.0%. The frequencies of patulin in domestic samples were 83.0%, while they were 57.7% in imported samples. Two domestic samples (0.6%) contained patulin above the regulatory limit, while none of the imported samples exceeded the limit. Among the online and offline samples, the frequencies of patulin were 76.4 and 82.1%. Two online samples (1.0%) for patulin exceeded the regulatory limit, whereas none of the offline samples exceeded the limit. These results showed it is important to monitor regularly the content of patulin in apples, hawthorns, and their products to ensure consumer food safety.

The Influence of Long-Term Storage on the Epiphytic Microbiome of Postharvest Apples and on Penicillium expansum Occurrence and Patulin Accumulation.

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.

Smartphone-Controlled Aptasensor for Voltammetric Detection of Patulin in Apple Juice.

Patulin (PAT) is a mycotoxin that adversely affects the health of humans and animals. PAT can be particularly found in products such as apples and apple juice and can cause many health problems if consumed. Therefore, accurate and sensitive determination of PAT is very important for food quality and human and animal health. A voltammetric aptasensor was introduced in this study for PAT determination while measuring the changes at redox probe signal. The limit of detection (LOD) was found to be 0.18 pg/mL in the range of 1-104 pg/mL of PAT in buffer medium under optimum experimental conditions. The selectivity of the PAT aptasensor against ochratoxin A, fumonisin B1 and deoxynivalenol mycotoxins was examined and it was found that the aptasensor was very selective to PAT. PAT determination was performed in an apple juice medium for the first time by using a smartphone-integrated portable device, and accordingly, an LOD of 0.47 pg/mL was achieved in diluted apple juice medium. A recovery range of 91.24-93.47% was obtained for PAT detection.

Optimization of Seleno-chitosan-phytic acid nanocomplex for efficient removal of patulin from apple juice.

A novel and effective adsorbent known as Seleno-chitosan-phytic acid nanocomplex (Se-CS-PA) has been developed specifically for efficiently removing patulin (PAT) from a simulated juice solution. The synthesis of Se-CS-PA nanocomplex was confirmed through Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), and energy dispersive X-Ray (EDX) analyses. Response surface methodology (RSM) was employed using central composite design (CCD) to examine the impact of four independent variables (PA concentration, amount of nano-complex, duration of interaction between PAT and nano-complex, and initial concentration of PAT) on the removal of PAT. PA concentration of 0.1 % with 2.1 g Se-CS-PA nanocomplex according to RSM polynomial equation and apple juice with 25 µg.L-1 PAT yielded a remarkable adsorption rate of 94.23 % and 87.52 % respectively after 7 h. The process of PAT adsorption was explained using the pseudo-first-order model (R2 = 0.8858) for the kinetic model and the Freundlich isotherm (R2 = 0.9988) for the isotherm model.

Exploring the Biocontrol Capability of Non-Mycotoxigenic Strains of Penicillium expansum.

Penicillium expansum is one the major postharvest pathogens of pome fruit during postharvest handling and storage. This fungus also produces patulin, which is a highly toxic mycotoxin that can contaminate infected fruits and their derived products and whose levels are regulated in many countries. In this study, we investigated the biocontrol potential of non-mycotoxigenic strains of Penicillium expansum against a mycotoxigenic strain. We analyzed the competitive behavior of two knockout mutants that were unable to produce patulin. The first mutant (∆patK) involved the deletion of the patK gene, which is the initial gene in patulin biosynthesis. The second mutant (∆veA) involved the deletion of veA, which is a global regulator of primary and secondary metabolism. At the phenotypic level, the ∆patK mutant exhibited similar phenotypic characteristics to the wild-type strain. In contrast, the ∆veA mutant displayed altered growth characteristics compared with the wild type, including reduced conidiation and abnormal conidiophores. Neither mutant produced patulin under the tested conditions. Under various stress conditions, the ∆veA mutants exhibited reduced growth and conidiation when exposed to stressors, including cell membrane stress, oxidative stress, osmotic stress, and different pH values. However, no significant changes were observed in the ∆patK mutant. In competitive growth experiments, the presence of non-mycotoxigenic strains reduced the population of the wild-type strain during in vitro growth. Furthermore, the addition of either of the non-mycotoxigenic strains resulted in a significant decrease in patulin levels. Overall, our results suggest the potential use of non-mycotoxigenic mutants, particularly ∆patK mutants, as biocontrol agents to reduce patulin contamination in food and feed.

WSC1 Regulates the Growth, Development, Patulin Production, and Pathogenicity of Penicillium expansum Infecting Pear Fruits.

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.

A film-like SERS aptasensor for sensitive detection of patulin based on GO@Au nanosheets.

Patulin (PAT) commonly contaminates fruits, posing a significant risk to human health. Therefore, a highly effective and sensitive approach in identifying PAT is warranted. Herein, a SERS aptasensor was constructed based on a two-dimensional film-like structure. GO@Au nanosheets modified with SH-cDNA were employed as capture probes, while core-shell Au@Ag nanoparticles modified with 4-MBA and SH-Apt were utilized as signal probes. Through the interaction between capture probes and signal probes, adjustable hotspots were formed, yielding a significant Raman signal. During sensing, the GO@Au-cDNA competitively attached to Au@AgNPs@MBA-Apt, resulting in an inverse relationship between PAT levels and SERS intensity. The acquired results exhibited linear responses to PAT within the range of 1-70 ng/mL, with a calculated limit of detection of 0.46 ng/mL. In addition, the SERS aptasensor exhibited satisfactory recoveries in apple samples, which aligned closely with HPLC. With high sensitivity and specificity, this method holds significant potential for PAT detection.

The small GTPase Ypt7 of Penicillium expansum is required for growth, patulin biosynthesis and virulence.

Ypt GTPases are the largest subfamily of small GTPases involved in membrane transport. Here, a PeYpt7 gene deletion mutant of P. expansum was constructed. The ΔPeYpt7 mutant showed reduced colony growth with abnormal mycelial growth, reduced conidiation, and insufficient spore development. The mutation rendered the pathogen susceptible to osmotic stress and cell wall stressors. In addition, the absence of PeYpt7 reduced patulin production in P. expansum and significantly limited gene expression (PatG, PatH, PatI, PatD, PatF, and PatL). In addition, the mutant showed attenuated virulence in infected fruit and reduced expression of pathogenic factors was (PMG, PG, PL, and GH1). Thus, PeYpt7 modulates the growth, morphology, patulin accumulation, and pathogenicity of P. expansum by limiting the expression of related genes.