Patulin Production Research Articles

Patulin production byPenicillium expansum isolates from apples during different steps of long-term storage

Penicillium expansum is the principal cause of blue mould rot and associated production of patulin, a weak mycotoxin, in apples worldwide.P. expansum growth and patulin production is observed during improper or long-term storage of apples. We have investigated the extent to which each successive step during long-term storage contributes to patulin production in variousP. expansum isolates. Fungal isolates collected on apples from several Belgian orchards/industries were identified to species level. Random amplification of polymorphic DNA (RAPD) analysis and β-tubulin gene sequencing identifiedP. expansum andPenicillium solitum as the most prevalentPenicillium species associated with Belgian apples. All 27P. expansum isolates and eight reference strains were characterised for their patulin production capacity on apple puree agar medium for five days under classical constant temperature and atmosphere conditions. Under these conditions, a large range of patulin production levels was observed. Based on this phenotypic diversity, fiveP. expansum isolates and one reference strain were selected forin vitro investigation of patulin production under representative conditions in each step of long-term apple storage. Patulin accumulation seemed highly strain dependent and no significant differences between the storage steps were observed. The results also indicated that a high spore inoculum may lead to a strong patulin accumulation even at cold temperatures (1 °C) combined with controlled atmosphere (CA) (3% O2, 1% CO2), suggesting that future control strategies may benefit from considering the duration of storage under CA conditions as well as duration of deck storage.

Dissecting inhibitory effect of boric acid on virulence and patulin production of Penicillium expansum

Pencillium expansum, the causal agent of blue mould rot, is one of the most destructive postharvest pathogens of pome fruit. It is also considered as the main source of the mycotoxin patulin which can lead to serious health problems. In the present study, the effects of exogenous boric acid (BA) on virulence and patulin production of P. expansum were evaluated. The results showed that 0.3% BA significantly inhibited the development of P. expansum in vitro and resulted in lower virulence to apple fruit. Moreover, BA suppressed the metabolism of carbohydrate, lipid and protein, reduce patulin production in P. expansum. Further analysis revealed that the expressions of the majority of the 15 genes involved in patulin biosynthesis were down-regulated under BA treatment. In addition, a global view of proteome alteration of P. expansum spores in response to 0.3% BA was acquired by an iTRAQ-based (Isobaric tags for relative and absolute quantitation) quantitative proteomic analysis. A total of 315 differentially expressed proteins (DEPs) (87 up-regulated and 228 down-regulated) were identified, and these DEPs were mainly involved in carbohydrate and protein metabolic pathways. Among them, septins and proteins related to ribosome component or ribosome biosynthesis were noticed for their significant up-regulation. Our results provided novel information for understanding the mechanism, by which BA regulated the growth of P. expansum and its virulence.

Assessing the effectiveness of Byssochlamys nivea and Scopulariopsis brumptii in pentachlorophenol removal and biological control of two Phytophthora species

Bioremediation and biological-control by fungi have made tremendous strides in numerous biotechnology applications. The aim of this study was to test Byssochlamys nivea and Scopulariopsis brumptii in sensitivity and degradation to pentachlorophenol (PCP) and in biological-control of Phytophthora cinnamomi and Phytophthora cambivora. B. nivea and S. brumptii were tested in PCP sensitivity and degradation in microbiological media while the experiments of biological-control were carried out in microbiological media and soil. The fungal strains showed low PCP sensitivity at 12.5 and 25 mg PCP L−1 although the hyphal size, fungal mat, patulin, and spore production decreased with increasing PCP concentrations. B. nivea and S. brumptii depleted completely 12.5 and 25 mg PCP L−1 in liquid culture after 28 d of incubation at 28 °C. Electrolyte leakage assays showed that both fungi have low sensitivity to 25 mg PCP L−1 and produced no toxic compounds for the plant. B. nivea and S. brumptii were able to inhibit the growth of the two plant pathogens in laboratory studies and reduce the mortality of chestnut plants caused by two Phytophthorae in greenhouse experiments. The two fungal strains did not produce volatile organic compounds able to reduce the growth of two plant pathogens tested.

Isoepoxydon dehydrogenase (idh) gene expression in relation to patulin production by Penicillium expansum under different temperature and atmosphere

Penicillium expansum growth and patulin production occur mainly at post-harvest stage during the long-term storage of apples. Low temperature in combination with reduced oxygen concentrations is commonly applied as a control strategy to extend apple shelf life and supply the market throughout the year. Our in vitro study investigated the effect of temperature and atmosphere on expression of the idh gene in relation to the patulin production by P. expansum. The idh gene encodes the isoepoxydon dehydrogenase enzyme, a key enzyme in the patulin biosynthesis pathway. First, a reverse transcription real-time PCR (RT-qPCR) method was optimized to measure accurately the P. expansum idh mRNA levels relative to the mRNA levels of three reference genes (18S, β-tubulin, calmodulin), taking into account important parameters such as PCR inhibition and multiple reference gene stability. Subsequently, two P. expansum field isolates and one reference strain were grown on apple puree agar medium (APAM) under three conditions of temperature and atmosphere: 20°C — air, 4°C — air and 4°C — controlled atmosphere (CA; 3% O2). When P. expansum strains reached a 0.5 and 2.0cm colony diameter, idh expression and patulin concentrations were determined by means of the developed RT-qPCR and an HPLC-UV method, respectively. The in vitro study showed a clear reduction in patulin production and down-regulation of the idh gene expression when P. expansum was grown under 4°C — CA. The results suggest that stress (low temperature and oxygen level) caused a delay of the fungal metabolism rather than a complete inhibition of toxin biosynthesis. A good correlation was found between the idh expression and patulin production, corroborating that temperature and atmosphere affected patulin production by acting at the transcriptional level of the idh gene. Finally, a reliable RT-qPCR can be considered as an alternative tool to investigate the effect of control strategies on the toxin formation in food.

A study on the physicochemical parameters for Penicillium expansum growth and patulin production: effect of temperature, pH, and water activity.

Penicillium expansum is among the most ubiquitous fungi disseminated worldwide, that could threaten the fruit sector by secreting patulin, a toxic secondary metabolite. Nevertheless, we lack sufficient data regarding the growth and the toxigenesis conditions of this species. This work enables a clear differentiation between the favorable conditions to the P. expansum growth and those promising for patulin production. A mathematical model allowing the estimation of the P. expansum growth rate according to temperature, a W, and pH, was also developed. An optimal growth rate of 0.92 cm/day was predicted at 24°C with pH level of 5.1 and high a W level of 0.99. The model's predictive capability was tested successfully on artificial contaminated apples. This model could be exploited by apple growers and the industrialists of fruit juices in order to predict the development of P. expansum during storage and apple processing.

Patulin is a cultivar-dependent aggressiveness factor favouring the colonization of apples by Penicillium expansum.

The blue mould decay of apples is caused by Penicillium expansum and is associated with contamination by patulin, a worldwide regulated mycotoxin. Recently, a cluster of 15 genes (patA-patO) involved in patulin biosynthesis was identified in P. expansum. blast analysis revealed that patL encodes a Cys6 zinc finger regulatory factor. The deletion of patL caused a drastic decrease in the expression of all pat genes, leading to an absence of patulin production. Pathogenicity studies performed on 13 apple varieties indicated that the PeΔpatL strain could still infect apples, but the intensity of symptoms was weaker compared with the wild-type strain. A lower growth rate was observed in the PeΔpatL strain when this strain was grown on nine of the 13 apple varieties tested. In the complemented PeΔpatL:patL strain, the ability to grow normally in apple and the production of patulin were restored. Our results clearly demonstrate that patulin is not indispensable in the initiation of the disease, but acts as a cultivar-dependent aggressiveness factor for P. expansum. This conclusion was strengthened by the fact that the addition of patulin to apple infected by the PeΔpatL mutant restored the normal fungal colonization in apple.

Phytic Acid Enhances Biocontrol Activity of Rhodotorula mucilaginosa against Penicillium expansum Contamination and Patulin Production in Apples.

The effect of Rhodotorula mucilaginosa in combination with phytic acid (PA) on blue mold decay and patulin contamination of apples was investigated. Results from this study show that different concentrations of PA were effective in reducing the disease incidence of apples and that PA at concentration of 4 μmol/mL, decreased the incidence of blue mold decay in apples from 86.1 to 62.5%, and showed higher control efficacy compared to untreated, control fruit during storage at 20°C. However, R. mucilaginosa combined with PA (4 μmol/mL) showed better control efficacy of blue mold decay than R. mucilaginosa used as single treatment, the disease incidence was reduced to 62.5% and lesion diameter on apples was reduced to 16.59 cm. In in vitro experiments, the addition of PA enhanced the biocontrol effect of R. mucilaginosa against the growth of Penicillium expansum and reduced patulin level when compared with either R. mucilaginosa or PA used separately. R. mucilaginosa together with PA, improved the inhibition of patulin production in wounded apples, decreasing the content of patulin by 89.6% compared to the control, under experimental conditions. Both R. mucilaginosa and R. mucilaginosa in combination with PA degraded patulin in vitro. In conclusion, the appropriate combination of R. mucilaginosa and PA may provide an effective biocontrol method for reducing postharvest decay of apples.

Molecular characterization of patulin producing and non-producing Penicillium species in apples from Morocco

The isolation of patulin-producing Penicillia in apples collected in different markets in four localities in Morocco is reported. Fungi were identified by β-tubulin sequencing and further characterized using a specific PCR-based method targeting the isoepoxydon dehydrogenase (IDH) gene to discriminate between patulin-producing and non-producing strains. Production of patulin was also evaluated using standard cultural and biochemical methods.Results showed that 79.5% of contaminant fungi belonged to the genus Penicillium and that Penicillium expansum was the most isolated species (83.9%) followed by Penicillium chrysogenum (~9.7%) and Penicillium crustosum (~6.4%).Molecular analysis revealed that 64.5% of the Penicillium species produced the expected IDH-amplicon denoting patulin production in these strains. However, patulin production was not chemically confirmed in all P. expansum strains. The isolation of IDH−/patulin+ strains poses the hypothesis that gentisylaldehyde is not a direct patulin precursor, supporting previous observations that highlighted the importance of the gentisyl alcohol in the production of this mycotoxin.Total agreement between IDH-gene detection and cultural/chemical methods employed was observed in 58% of P. expansum strains and for 100% of the other species isolated.Overall the data reported here showed a substantial genetic variability within P. expansum population from Morocco.

Bioactive compounds from mustard flours for the control of patulin production in wheat tortillas

Patulin (PAT) is a toxic fungal metabolite produced by Penicillium, Aspergillus and Byssochlamys growing especially in fruit and cereals. PAT exhibits a number of toxic effects in animals and its presence in food is undesirable. In this study the reduction of the mycotoxin PAT produced by a strain of Penicillium expansum, on wheat tortillas was studied using volatile bioactive compounds present in the oriental and yellow mustard flour and also using the standard solution of the antifungal compound allyl isothiocyanate (AIT), developing an active packaging with two different systems of release of those bioactive compounds. Also the kinetic of volatilization of the compounds used in the bioactive packaging was evaluated using the technique of the gas chromatography (GC) coupled to the flame ionization detector (FID). The PAT was extracted from the samples using the QUECHERS methodology and was determined using the technique of the liquid chromatography (LC) coupled to the mass spectrometry detector in tandem (MS/MS). The maximum of volatilization of the AIT in the bioactive packaging is produced between 1 and 24 h depending on the volatilization technique and is stable during two months, whereas the reduction of PAT evidenced in the samples treated ranged from 80 to 100%.

In vitro antifungal activity of allyl isothiocyanate (AITC) against Aspergillus parasiticus and Penicillium expansum and evaluation of the AITC estimated daily intake

Isothiocyanates (ITCs) are natural compounds derived from cruciferous vegetables produced by enzymatic conversion of metabolites called glucosinolates. They are potentially useful antimicrobial compounds for food applications have been shown to be promising agents against cancer in human cell culture, animal models, and in epidemiological studies. In this study, the antifungal activity of the allyl isothiocyanate (AITC) was evaluated on two mycotoxigenic fungi as Aspergillus parasiticus and Penicillium expnsum, aflatoxins (AFs) and patulin (PAT) producers, employing an assay on solid medium. Also an approximation of the risk evaluation associated to the intake of food treated with the AITC to reduce the risk of fungi spoilage has been evaluated. On solid medium and after 20 days incubation the strain of Penicillium expansum was inhibited with AITC quantities highest than 50 mg, whereas the strain of A. parasiticus was sensible to AITC doses highest than 5 mg. The analysis of the risk assessment associated to the intake of several food classes treated with the bioactive compound AITC to prevent fungi spoilage evidenced that this product can be considered as safe due that the estimated daily intakes (EDIs) are always lower than the AITC Admissible Daily intake (ADI).

Efficacy Evaluation of Iraqi Propolis Against Gray Mold of Stored Orange Caused by Penicillium digitatum

This study was conducted to evaluate Iraqi propolis against gray mold on orange. Propolis Ethanolic Extract (PEE) in three concentrations 1, 2 and 3% were used to treated orange treatments separately and storage at 25±2°C for three weeks. Results showed a significant reduced in disease severity in the first, second and third week for all PEE concentrations compared with infected control. The best treatment was 3% in disease severity reduction. Disease incidence was significantly reduced with the treatment treated with PEE for all concentrations compared with the pathogen treatment, both concentration of PEE 2 and 3% was the most effective. Also, all PEE concentrations reduce depth of the mold area compared with pathogen treatment. There are no significant differences in patulin production between PEE and pathogen treatments was founded.

Colonization of grapes berries and cider by potential producers of patulin

The aim of this study was to detect potential producers of mycotoxin patulin from grapes (berries, surface sterilized berries - endogenous mycobiota and grape juice) of Slovak origin. We analyzed 47 samples of grapes, harvested in 2011, 2012 and 2013 from various wine-growing regions. For the isolation of species we used the method of direct plating berries and surface-sterilized berries (using 1% freshly pre-pared chlorine) berries on DRBC (Dichloran Rose Bengal Chloramphenicol agar). For the determination of fungal contamination of grape juice we used plate-dilution method and DRBC and DG18 (Dichloran 18% Glycerol agar) as media. The cultivation in all modes of inoculation was carried at 25 ±1 °C, for 5 to 7 days. After incubation Aspergillus and Pencillium isolates were inoculated on the identification media. The potential producers of patulin were isolated from 23 samples berries, 19 samples of surface-sterilized berries and 6 samples of grape juice. Overall, the representatives of producers of patulin were detected in 32 (68.1%) samples (75 isolates). In this work we focused on the detection of potential producers of patulin, Penicillium expansum (the most important producer of patulin in fruits), Penicillium griseofulvum and Aspergillus clavatus were isolated. Chosen isolates of potential patulin producers were tested for the ability to produce relevant mycotoxins in in vitro conditions using thin layer chromatography method. The ability to produce patulin in in vitro condition was detected in 82% of isolates of Penicillium expansum, 65% of Penicillium griseofuvum and 100% of Aspergillus clavatus. Some isolates of Penicillium expansum were able to produce citrinin and roquefortine C, Penicillium griseofulvum cyclopiazonic acid, griseofulvin and roquefortin C, also.

Effects of carbon, nitrogen and ambient pH on patulin production and related gene expression in Penicillium expansum

Patulin, a potent mycotoxin which can cause serious health concerns, is mainly produced in foods by Penicillium expansum. Environmental factors play important roles in regulating biosynthesis of mycotoxins; however, information about the effects of environmental factors on patulin production and the involved mechanisms in P. expansum is limited. Here, we investigated the effects of different carbon (C) and nitrogen (N) sources, and ambient pH on patulin production in three P. expansum strains T01, M1 and Pe21, and the expression profile of 15 genes involved in patulin biosynthetic pathway. It was found that C and N sources and pH had great influence on patulin production in P. expansum. In general, patulin production of all three P. expansum strains showed similar trends under different C and N sources and pH conditions, though there were some differences in the optimal conditions among these strains. Glucose-containing sugars, complex N sources, and acidic conditions were favorable conditions for patulin production. The results of RT-qPCR showed that the relative expressions of most of the patulin genes were up-regulated under patulin-permissive conditions, indicating that patulin biosynthesis was mainly regulated at transcriptional level by these environmental factors. These findings will provide useful information to better understand the regulation mechanisms of patulin biosynthesis, and be helpful in developing effective means for controlling patulin contamination.

Ozone for post-harvest treatment of apple fruits

Different biotic contaminations can affect apple production. Among these, infections by Penicillium expansum , the causal agent of blue-green post-harvest rot and patulin production, is particularly important. Fruit of the apple varieties: ‘Royal Gala’, ‘Golden Delicious’ and ‘Fuji’ were challenged with a patulin-producing P. expansum strain and stored at 1 ± 1°C in presence of gaseous ozone at 0.5 μL L -1 for 2 months. During the storage period, fungal populations, the biosynthesis of patulin and the activity of some Pathogenesis Related Proteins (glucanase, peroxidase and phenylalanine ammonia-lyase) were evaluated. Ozone treatment reduced fungal populations and patulin production. The activity of the assayed enzymes was not directly or clearly correlated with the inhibiting effect of ozone. These results indicate that ozone could be used to increase storage duration of apple varieties to maintain their quality.

Inhibitory effect of exogenous sodium bicarbonate on development and pathogenicity of postharvest disease Penicillium expansum

Penicillium expansum, a widespread filamentous fungus, is a major causative agent of fruit decay and may lead to the production of patulin which causes harmful effects on human health. In this study, P. expansum isolated from naturally infected pears (Pyrus bretschneideri Rehd.) was identified by morphological observation and rDNA-internal transcribed spacer analysis. Then, the effects of exogenous sodium bicarbonate (NaHCO3) on development and pathogenicity of P. expansum were evaluated in vitro and in vivo. Results indicated that NaHCO3 at 0.6% (w/v) significantly (P<0.05) reduced the germination of P. expansum conidia by up to 80% compared to the control after 10h incubation. NaHCO3 also showed good ability to inhibit germ tube elongation, mycelia expansion and hypha production of P. expansum. The lesion diameter and disease incidence of blue molds were markedly reduced by 0.6% NaHCO3 treatment. Loss of membrane integrity was examined and quantified under 0.6% NaHCO3 condition by the method of propidium iodide fluorescent staining. Furthermore, we found that NaHCO3 obviously affected the relative expressions of four genes involved in patulin biosynthesis and effectively prevented patulin accumulation. These data will provide theoretical foundations for improving the application potential of NaHCO3 on postharvest horticulture pathogens control.

Mycoflora and Patulin-producing strains of cereals in North-Western Morocco

Cereals are considered a food that is exposed to fungal contamination and mycotoxin production. The present study was conducted to evaluate and identify the patulin-producing fungal flora contaminating the wheat and bar-ley grain in the field, the storage silo, and products of transformation (flour, semolina). Sampling was carried out in the region of Meknes (Morocco) dur-ing the growing season of 2012. The study of macroscopic and microscopic characters enabled to isolate and identify over 140 isolates belonging mainly to the genuses Aspergillus, Penicillium, Fusarium, Cladosporium, Alternaria, Ulocladium, Rhizopus, Mucor and Trichoderma. Of the 51 isolates of Penicilli-um, eight were found to be producer of patulin by TLC and HPLC. Six out of the eight mycotoxigenic isolates were classified and identified as Penicillium expansum. The patulin content varied from one species to another and reached 41.72 μg/mL in one of the Penicillium expansum isolates.

Fungi Isolated from Traditional and Exotic Apple Varieties from Portugal and Patulin Production

The objective of our study was to examine the effects of cultivar type on developed fungi species and evaluate the potential for patulin production by fungi. In addition, patulin diffusion was also investigated. The experiments were carried out in traditional (Bravo de Esmolfe) and exotic apples (Golden, Starking, Fuji, Reineta Parda and Gala Galaxy) varieties from Portugal. High-performance liquid chromatography with solid phase extraction and UV detection (SPE-HPLC-UV) was validated and used to analyze patulin in the apple. The most prevalent fungal population was Penicillium spp and 27% of rotten fruits had patulin. Fungi of the genera Cladosporium spp., Alternaria spp., Fusarium spp. and Aspergillus spp. were also found even in apples without patulin production. The variety with the highest production of patulin was Bravo Esmolfe, however this variety showed the lowest prevalence of Penicillium spp. compared to other varieties of apples where was detected patulin.Patulin was not detected in any apples of Fuji and Gala varieties, despite having been identified fungi usually associated with the production of patulin. Thus, these two varieties are presented as the most suitable for the production of the apple based-foods.

Sequencing, physical organization and kinetic expression of the patulin biosynthetic gene cluster from Penicillium expansum

Patulin is a polyketide-derived mycotoxin produced by numerous filamentous fungi. Among them, Penicillium expansum is by far the most problematic species. This fungus is a destructive phytopathogen capable of growing on fruit, provoking the blue mold decay of apples and producing significant amounts of patulin. The biosynthetic pathway of this mycotoxin is chemically well-characterized, but its genetic bases remain largely unknown with only few characterized genes in less economic relevant species. The present study consisted of the identification and positional organization of the patulin gene cluster in P. expansum strain NRRL 35695. Several amplification reactions were performed with degenerative primers that were designed based on sequences from the orthologous genes available in other species. An improved genome Walking approach was used in order to sequence the remaining adjacent genes of the cluster. RACE-PCR was also carried out from mRNAs to determine the start and stop codons of the coding sequences. The patulin gene cluster in P. expansum consists of 15 genes in the following order: patH, patG, patF, patE, patD, patC, patB, patA, patM, patN, patO, patL, patI, patJ, and patK. These genes share 60–70% of identity with orthologous genes grouped differently, within a putative patulin cluster described in a non-producing strain of Aspergillus clavatus. The kinetics of patulin cluster genes expression was studied under patulin-permissive conditions (natural apple-based medium) and patulin-restrictive conditions (Eagle's minimal essential medium), and demonstrated a significant association between gene expression and patulin production. In conclusion, the sequence of the patulin cluster in P. expansum constitutes a key step for a better understanding of the mechanisms leading to patulin production in this fungus. It will allow the role of each gene to be elucidated, and help to define strategies to reduce patulin production in apple-based products.

Antifungal activity of silver ion on ultrastructure and production of aflatoxin B1 and patulin by two mycotoxigenic strains, Aspergillus flavus OC1 and Penicillium vulpinum CM1

The antifungal activity of silver ion from silver nitrate solution was tested against two pathogenic and toxigenic fungal strains. The first was Aspergillus flavus OC1, a clinical aflatoxigenic strain that causes fungal keratitis and the second was Penicillium vulpinum CM1, a maize-pathogenic strain that is positive for patulin (PAT) producing ability. Agar well diffusion assays on yeast sucrose (YES) agar were applied for determination of the antifungal activity of silver ions either filter- or autoclaved-sterilized. Transmission electron microscopy was used to analyze the cellular effects of silver ion. The mycotoxins AFB1 and PAT were analyzed in the fungal strains cultures treated with silver ion. Filter-sterilized ions have a greater potential for growth inhibition of both fungal strains than autoclaved-sterilized ions. The minimal inhibitory concentration of the filter-sterilized ions against A. flavus OC1 was 70 μg mL(-1) and against P. vulpinum CM1 was 60 μg mL(-1) and that the minimum fungicidal concentration was 120 μg mL(-1) against the first strain and 80 μg mL(-1) against the second strain. Hyphal cells treated with silver ion showed considerable changes in the nature of cell membranes and cytoplasmic organelles. Silver applied to YES broth inhibited mycelial growth and AFB1 and PAT formation of both strains. Growth and mycotoxin production appeared to be correlated processes. These findings indicate the future possibility to use silver ion as substitute for synthetic fungicides to control the growth of pathogenic fungi and their mycotoxin production.

Accumulation of the Mycotoxin Patulin in the Presence of Gluconic Acid Contributes to Pathogenicity of Penicillium expansum

Penicillium expansum, the causal agent of blue mold rot, causes severe postharvest fruit maceration through secretion of D-gluconic acid (GLA) and secondary metabolites such as the mycotoxin patulin in colonized tissue. GLA involvement in pathogenicity has been suggested but the mechanism of patulin accumulation and its contribution to P. expansum pathogenicity remain unclear. The roles of GLA and patulin accumulation in P. expansum pathogenicity were studied using i) glucose oxidase GOX2-RNAi mutants exhibiting decreased GOX2 expression, GLA accumulation, and reduced pathogenicity; ii) IDH-RNAi mutants exhibiting downregulation of IDH (the last gene in patulin biosynthesis), reduced patulin accumulation, and no effect on GLA level; and iii) PACC-RNAi mutants exhibiting downregulation of both GOX2 and IDH that reduced GLA and patulin production. Present results indicate that conditions enhancing the decrease in GLA accumulation by GOX2-RNAi and PACC-RNAi mutants, and not low pH, affected patulin accumulation, suggesting GLA production as the driving force for further patulin accumulation. Thus, it is suggested that GLA accumulation may modulate patulin synthesis as a direct precursor under dynamic pH conditions modulating the activation of the transcription factor PACC and the consequent pathogenicity factors, which contribute to host-tissue colonization by P. expansum.