The response of growth and patulin production of postharvest pathogen Penicillium expansum to exogenous potassium phosphite treatment

The potato rhizosphere microbiota correlated to the yield of three different regions in Korea

We examined potato rhizosphere bacterial and fungal communities across three regions: Cheongju, Pyeongchang, and Gangneung. These regions have varying soil and climate conditions, resulting in different yields. We found that precipitation was the main limiting factor in our study while soil physiochemical factors affect bacterial and fungal microbiota in correlation with yield. Both bacterial and fungal microbiota showed distinct patterns according to the regions. ASVs positively correlated with yield were predominantly found in the Pyeongchang region which also produced the highest yields, while ASVs negatively correlated with yield were associated with Gangneung where the lowest yields were observed. The greatest bacterial and fungal diversity was detected in Pyeongchang consisting of Propionibacteriales, Burkholderiales, and Vicinamibacteriales. Gangneung, on the other hand primarily belong to Sordariales, Mortierellales, Cystofilobasidiales, and Tremellales. The putative yield-negative ASVs detected in Gangneung may have been influenced by drought stress. This work has highlighted key bacterial and fungal taxa as well as core taxa that may potentially be associated with high and low yields of potato in relation to metadata which includes soil chemical and physical parameters as well as weather data. Taken together we suggest that this information can be used to assess site suitability for potato production.

Natural feed additives and bioactive supplements versus chemical additives as a safe and practical approach to combat foodborne mycotoxicoses

This review highlights the possible hazard of mycotoxins occurrence in foods and feeds in regards to foodborne diseases. The possible management of the risk of contamination of foods and feeds with mycotoxins by using natural feed additives, protecting against deleterious effects of mycotoxins or inhibiting the growth of fungi and mycotoxin production, is deeply investigated in the available literature and some effective measures for safe utilization of mycotoxin contaminated feed/food are proposed. The biological methods of decontamination, degradation or biotransformation of mycotoxins are deeply analyzed and discussed. Some natural antagonists against target fungi are also reviewed and a comparison is made with conventional fungicides for ensuring a safe prevention of mycotoxin contamination. The most common and useful chemical methods of mycotoxins decontamination of agricultural commodities or raw materials are also investigated, e.g., chemical additives inactivating or destroying and/or adsorbing mycotoxins as well as chemical additives inhibiting the growth of fungi and mycotoxin production. The practical use and safety of various kind of feed/food additives or herbal/biological supplements as possible approach for ameliorating the adverse effects of some dangerous mycotoxins is deeply investigated and some suggestions are given. Various possibilities for decreasing mycotoxins toxicity, e.g., by clarifying the mechanisms of their toxicity and using some target antidotes and vitamins as supplements to the diet, are also studied in the literature and appropriate discussions or suggestions are made in this regard. Some studies on animal diets such as low carbohydrate intake, increased protein content, calorie restriction or the importance of dietary fats are also investigated in the available literature for possible amelioration of the ailments associated with mycotoxins exposure. It could be concluded that natural feed additives and bioactive supplements would be more safe and practical approach to combat foodborne mycotoxicoses as compared to chemical additives.

The Identification and Comparative Analysis of Non-Coding RNAs in Spores and Mycelia of Penicillium expansum

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.

New insights into the persistent effect of transient cinnamaldehyde vapor treatment on the growth and aflatoxin synthesis of Aspergillus flavus

The antimicrobial effects of continuous treatment with essential oils (EOs) in both liquid and gaseous phases have been intensively studied. Due to their rapid volatility, the effects of EOs on microorganisms after transient treatment are also worth exploring. In this work, the persistent effects of cinnamaldehyde (CA) vapor on Aspergillus flavus were detected by a series of biochemical analyses. Transcriptome analysis was also conducted to study the gene expression changes between recovered and normal A. flavus. When CA vapor was removed, biochemical analyses showed that the oxidative stress induced by the antimicrobial atmosphere was alleviated, and almost all the damaged functions were restored apart from mitochondrial function. Remarkably, the suppressed aflatoxin production intensified, which was confirmed by the up-regulation of most genes in the aflatoxin synthetic gene cluster, the velvet-related gene FluG and the aflatoxin precursor acetyl-CoA. Transcriptomic analysis also demonstrated significant changes in secondary metabolism, energy metabolism, oxidative stress, and amino acid metabolism in the recovery group. Taken together, these findings provide new insights into the mechanisms underlying the response of A. flavus to CA vapor treatment and will guide the rational application of EOs.

Antifungal Activities of Bacillus mojavensis BQ-33 towards the Kiwifruit Black Spot Disease Caused by the Fungal Pathogen Didymella glomerata

‘Hongyang’ kiwifruit (Actinidia chinensis, cultivar ‘Hongyang’) black spot disease is caused by the fungal pathogen Didymella glomerata, and is a serious disease, causing considerable losses to the kiwifruit industry during growth of the fruit. Hence, we aimed to identify a potential biocontrol agent against D. glomerata. In this study, bacterial isolates from the rhizosphere soil of kiwifruit were tested for their potential antifungal activity against selected fungal pathogens. Based on a phylogenetic tree constructed using sequences of 16S rDNA and the gyrA gene, BQ-33 with the best antifungal activity was identified as Bacillus mojavensis. We evaluated the antagonistic activity and inhibitory mechanism of BQ-33 against D. glomerata. Confrontation experiments showed that both BQ-33 suspension and the sterile supernatant (SS) produced by BQ-33 possessed excellent broad-spectrum antifungal activity. Furthermore, the SS damaged the cell membrane and cell wall of the mycelia, resulting in the leakage of a large quantity of small ions (Na⁺, K⁺), soluble proteins and nucleic acids. Chitinase and β-1,3-glucanase activities in SS increased in correlation with incubation time and remained at a high level for several days. An in vivo control efficacy assay indicated that 400 mL L⁻¹ of SS completely inhibited kiwifruit black spot disease caused by D. glomerata. Therefore, BQ-33 is a potential biocontrol agent against kiwifruit black spot and plant diseases caused by other fungal pathogens. To our knowledge, this is the first report of the use of a rhizosphere microorganism as a biocontrol agent against kiwifruit black spot disease caused by D. glomerata.

Combined transcriptome and metabolome analyses reveal the potential mechanism for the inhibition of Penicillium digitatum by X33 antimicrobial oligopeptide

Penicillium digitatum is the primary spoilage fungus that causes green mold during postharvest in citrus. To reduce economic losses, developing more efficient and less toxic natural antimicrobial agents is urgently required. We previously found that the X33 antimicrobial oligopeptide (X33 AMOP), produced by Streptomyces lavendulae X33, exhibited a sterilization effect on P. digitatum. In this study, the effects, and physiological mechanisms of X33 AMOP as an inhibitor of P. digitatum were investigated. The transcriptional and metabolome profiling of P. digitatum exposed to X33 AMOP revealed 3648 genes and 190 metabolites that were prominently changed. The omics analyses suggested that X33 AMOP mainly inhibited P. digitatum growth by affecting cell integrity, genetic information delivery, oxidative stress tolerance, and energy metabolism. These findings provide helpful information regarding the antimicrobial mechanism of X33 AMOP against P. digitatum at the molecular level and indicate that X33 AMOP is a potential candidate to control P. digitatum.

Mining RNA-Seq Data to Depict How Penicillium digitatum Shapes Its Transcriptome in Response to Nanoemulsion

Penicillium digitatum is the most severe pathogen that infects citrus fruits during storage. It can cause fruit rot and bring significant economic losses. The continuous use of fungicides has resulted in the emergence of drug-resistant strains. Consequently, there is a need to develop naturally and efficiently antifungal fungicides. Natural antimicrobial agents such as clove oil, cinnamon oil, and thyme oil can be extracted from different plant parts. They exhibited broad-spectrum antimicrobial properties and have great potential in the food industry. Here, we exploit a novel cinnamaldehyde (CA), eugenol (EUG), or carvacrol (CAR) combination antifungal therapy and formulate it into nanoemulsion form to overcome lower solubility and instability of essential oil. In this study, the antifungal activity evaluation and transcriptional profile of Penicillium digitatum exposed to compound nanoemulsion were evaluated. Results showed that compound nanoemulsion had a striking inhibitory effect on P. digitatum in a dose-dependent manner. According to RNA-seq analysis, there were 2,169 differentially expressed genes (DEGs) between control and nanoemulsion-treated samples, including 1,028 downregulated and 1,141 upregulated genes. Gene Ontology (GO) analysis indicated that the DEGs were mainly involved in intracellular organelle parts of cell component: cellular respiration, proton transmembrane transport of biological process, and guanyl nucleotide-binding molecular function. KEGG analysis revealed that metabolic pathway, biosynthesis of secondary metabolites, and glyoxylate and dicarboxylate metabolism were the most highly enriched pathways for these DEGs. Taken together, we can conclude the promising antifungal activity of nanoemulsion with multiple action sites against P. digitatum. These outcomes would deepen our knowledge of the inhibitory mechanism from molecular aspects and exploit naturally, efficiently, and harmlessly antifungal agents in the citrus postharvest industry.

Aspergillus derived mycotoxins in food and the environment: Prevalence, detection, and toxicity

Aspergillus species are the paramount ubiquitous fungi that contaminate various food substrates and produce biochemicals known as mycotoxins. Aflatoxins (AFTs), ochratoxin A (OTA), patulin (PAT), citrinin (CIT), aflatrem (AT), secalonic acids (SA), cyclopiazonic acid (CPA), terrein (TR), sterigmatocystin (ST) and gliotoxin (GT), and other toxins produced by species of Aspergillus plays a major role in food and human health. Mycotoxins exhibited wide range of toxicity to the humans and animal models even at nanomolar (nM) concentration. Consumption of detrimental mycotoxins adulterated foodstuffs affects human and animal health even trace amounts. Bioaerosols consisting of spores and hyphal fragments are active elicitors of bronchial irritation and allergy, and challenging to the public health. Aspergillus is the furthermost predominant environmental contaminant unswervingly defile lives with a 40-90 % mortality risk in patients with conceded immunity. Genomics, proteomics, transcriptomics, and metabolomics approaches useful for mycotoxins' detection which are expensive. Antibody based detection of toxins chemotypes may result in cross-reactivity and uncertainty. Aptamers (APT) are single stranded DNA (ssDNA/RNA), are specifically binds to the target molecules can be generated by systematic evolution of ligands through exponential enrichment (SELEX). APT are fast, sensitive, simple, in-expensive, and field-deployable rapid point of care (POC) detection of toxins, and a better alternative to antibodies.

Patulin in food: A mycotoxin concern for human health and its management strategies

The mycotoxin patulin is primarily produced as a secondary metabolite by numerous fungal species and predominantly by Aspergillus, Byssochlamys, and Penicillium species. It is generally associated with fungal infected food materials. Penicillium expansum is considered the only fungal species liable for patulin contamination in pome fruits, especially in apples and apple-based products. This toxin in food poses serious health concerns and economic threat, which has aroused the need to adopt effective detection and mitigation strategies. Understanding its origin sources and biosynthetic mechanism stands essential for efficiently designing a management strategy against this fungal contamination. This review aims to present an updated outline of the sources of patulin occurrence in different foods and their biosynthetic mechanisms. It further provides information regarding the detrimental effects of patulin on human and agriculture as well as its effective detection, management, and control strategies.

Cinnamon Oil Inhibits Penicillium expansum Growth by Disturbing the Carbohydrate Metabolic Process

Penicillium expansum is a major postharvest pathogen that mainly threatens the global pome fruit industry and causes great economic losses annually. In the present study, the antifungal effects and potential mechanism of cinnamon oil against P. expansum were investigated. Results indicated that 0.25 mg L⁻¹ cinnamon oil could efficiently inhibit the spore germination, conidial production, mycelial accumulation, and expansion of P. expansum. In addition, it could effectively control blue mold rots induced by P. expansum in apples. Cinnamon oil could also reduce the expression of genes involved in patulin biosynthesis. Through a proteomic quantitative analysis, a total of 146 differentially expressed proteins (DEPs) involved in the carbohydrate metabolic process, most of which were down-regulated, were noticed for their large number and functional significance. Meanwhile, the expressions of 14 candidate genes corresponding to DEPs and the activities of six key regulatory enzymes (involving in cellulose hydrolyzation, Krebs circle, glycolysis, and pentose phosphate pathway) showed a similar trend in protein levels. In addition, extracellular carbohydrate consumption, intracellular carbohydrate accumulation, and ATP production of P. expansum under cinnamon oil stress were significantly decreased. Basing on the correlated and mutually authenticated results, we speculated that disturbing the fungal carbohydrate metabolic process would be partly responsible for the inhibitory effects of cinnamon oil on P. expansum growth. The findings would provide new insights into the antimicrobial mode of cinnamon oil.

Prevention and detoxification of patulin in apple and its products: A review

Patulin-producing fungi pose an unavoidable problem for apple and its product quality, thereby threatening human and/or animal health. Studies on controlling the patulin-producing fungal growth and patulin contamination in apple and its products by physical methods, chemical fungicides, and biological methods have been performed for decades, but patulin contamination has not been addressed. Here, the important of studying regulation mechanism of patulin production in apple at the protein expression and metabolism levels is proposed, which will facilitate the development of controlling patulin production by using physical, chemical, and biological methods. Furthermore, the advantages or disadvantages and effects or mechanisms of using physical, chemical, biological methods to control the decay caused by Penicillium expansum and to remove patulin in food was discussed. The development of physical methods to remove patulin depends on the development of special equipment. Chemical methods are economical and efficient, if we have ensured that there are no unknown reactions or toxic by-products by using these chemicals. The biological method not only effectively controls the decay caused by Penicillium espansum, but also removes the toxins that already exist in the food. Degradation of patulin by microorganisms or biodegradation enzymes is an efficient and promising method to remove patulin in food if the microorganisms used and the degradation products are completely non-toxic.

Effects of Peptide C12-OOWW-NH2 on Transcriptome and Cell Wall of the Postharvest Fungal Pathogen Penicillium digitatum

In this study, the transcriptional profiling of Penicillium digitatum after C₁₂O₃TR treatment was analyzed by RNA-Seq technology. A total of 2562 and 667 genes in P. digitatum were differentially expressed after 2 and 12 h treatment, respectively. These genes were respectively mapped to 91 and 79 KEGG pathways. The expression patterns of differentially expressed genes (DEGs) at 2 and 12 h were similar, mainly were the metabolic processes in cell wall, cell membrane, genetic information and energy. Particularly, the main metabolic process which was affected by C₁₂O₃TR stress for 2 and 12 h was cell integrity, including cell wall and cell membrane. The changes of chitin in cell wall was observed by Calcofluor White (CFW) staining assay. The weaker blue fluorescence in the cell wall septa, the decrease of β-1, 3-glucan synthase activity and the increase of chitinase and AKP activity showed that C₁₂O₃TR could damage the cell wall integrity. In conclusion, these results suggested that C₁₂O₃TR could inhibit the growth of P. digitatum through various mechanisms at transcriptional level, and could influence the cell wall permeability and integrity.

Genomic Insights Into Sugar Adaptation in an Extremophile Yeast Zygosaccharomyces rouxii

The osmotolerant Zygosaccharomyces rouxii is known for its trait to survive in extreme high sugar environments. This ability determines its role in the fermentation process and leads to yeast spoilage in the food industry. However, our knowledge of the gene expression in response to high sugar stress remains limited. Here, we conducted RNA-sequencing (RNA-seq) under different sugar concentrations of the spoilage yeast, Z. rouxii, which exhibit extremely high tolerance to sugar stress. The obtained differentially expressed genes (DEGs) are significantly different to that of the Saccharomyces cerevisiae, which is sensitive to extreme high sugar stress. Most of the DEGs participated in the “glucan synthesis,” “transmembrane transport,” “ribosome,” etc. In this work, we also demonstrated that the gene ZYRO0B03476g (ZrKAR2) encoding Kar2p can significantly affect the growth of Z. rouxii under high sugar stress. In addition, we combined with a previous study on the genome sequence of Z. rouxii, indicating that several gene families contain significantly more gene copies in the Z. rouxii lineage, which involved in tolerance to sugar stress. Our results provide a gene insight for understanding the high sugar tolerance trait, which may impact food and biotechnological industries and improve the osmotolerance in other organisms.

Cuminal Inhibits Trichothecium roseum Growth by Triggering Cell Starvation: Transcriptome and Proteome Analysis

Trichothecium roseum is a harmful postharvest fungus causing serious damage, together with the secretion of insidious mycotoxins, on apples, melons, and other important fruits. Cuminal, a predominant component of Cuminum cyminum essential oil has proven to successfully inhibit the growth of T. roseum in vitro and in vivo. Electron microscopic observations revealed cuminal exposure impaired the fungal morphology and ultrastructure, particularly the plasmalemma. Transcriptome and proteome analysis was used to investigate the responses of T. roseum to exposure of cuminal. In total, 2825 differentially expressed transcripts (1516 up and 1309 down) and 225 differentially expressed proteins (90 up and 135 down) were determined. Overall, notable parts of these differentially expressed genes functionally belong to subcellular localities of the membrane system and cytosol, along with ribosomes, mitochondria and peroxisomes. According to the localization analysis and the biological annotation of these genes, carbohydrate and lipids metabolism, redox homeostasis, and asexual reproduction were among the most enriched gene ontology (GO) terms. Biological pathway enrichment analysis showed that lipids and amino acid degradation, ATP-binding cassette transporters, membrane reconstitution, mRNA surveillance pathway and peroxisome were elevated, whereas secondary metabolite biosynthesis, cell cycle, and glycolysis/gluconeogenesis were down regulated. Further integrated omics analysis showed that cuminal exposure first impaired the polarity of the cytoplasmic membrane and then triggered the reconstitution and dysfunction of fungal plasmalemma, resulting in handicapped nutrient procurement of the cells. Consequently, fungal cells showed starvation stress with limited carbohydrate metabolism, resulting a metabolic shift to catabolism of the cell's own components in response to the stress. Additionally, these predicaments brought about oxidative stress, which, in collaboration with the starvation, damaged certain critical organelles such as mitochondria. Such degeneration, accompanied by energy deficiency, suppressed the biosynthesis of essential proteins and inhibited fungal growth.

The characteristics, occurrence, and toxicological effects of patulin

Mycotoxins are the secondary metabolites secreted by different types of fungi to which humans can get exposed mainly via ingestion. Patulin (C₇H₆O₄) is a polyketide lactone produced by various fungal specifies, including Penicillium expansum as the main producer. P. expansum can infect different fruits and vegetables yet it has preference to apples in which they cause blue rot. Therefore, apples and apple-based food products are the main source of Patulin exposure for humans. Patulin was first identified in 1943 under the name of tercinin as a possible antimicrobial agent. Although it is categorized as a non-carcinogen, Patulin has been linked, in the last decades, to neurological, gastrointestinal, and immunological adverse effects, mainly causing liver and kidney damages. In this review, the characteristics of and possible human exposure pathways to Patulin are discussed. Various surveillance and toxicity studies on the levels of Patulin in various food products and effects of Patulin on cells and animal models have been documented as well. Importance of epidemiological studies and a summary of the possible toxicity mechanisms are highlighted with a case study. The commonly used control methods as described in the literature are also discussed to guide future researchers to focus on mitigating mycotoxins contamination in the food industry.

Effect of chlorine dioxide (ClO2 ) on patulin produced by Penicillum expansum and involved mechanism

BACKGROUND

Patulin, produced by Penicillium expansum in apple fruit, has side effects affecting human and animal health. The effect of chlorine dioxide (ClO₂ ) on patulin production, and the mechanisms involved in this, were investigated.

RESULTS

Patulin production by P. expansum was reduced by ClO₂ treatment, both in apples and in a potato dextrose broth (PDB) medium, which was attributed to the antifungal effect of ClO₂ , but not the direct reaction between ClO₂ and patulin. Fumigation with ClO₂ also significantly reduced disease development in apples infected with P. expansum, and inhibited mycelial growth and spore germination. After ClO₂ treatment, P. expansum mycelial morphology was strongly affected, leading to the loss of plasma membrane integrity and causing cellular leakage.

CONCLUSION

These data provide useful information that enables the inhibitory mechanism of ClO₂ on patulin production by P. expansum to be better understood. It can also assist the development of effective methods to control patulin production in apples and other postharvest fruits. © 2018 Society of Chemical Industry.

Current Status and Future Opportunities of Omics Tools in Mycotoxin Research

Mycotoxins are toxic secondary metabolites of low molecular weight produced by filamentous fungi, such as Aspergillus, Fusarium, and Penicillium spp. Mycotoxins are natural contaminants of agricultural commodities and their prevalence may increase due to global warming. Dangerous mycotoxins cause a variety of health problems not only for humans, but also for animals. For instance, they possess carcinogenic, immunosuppressive, hepatotoxic, nephrotoxic, and neurotoxic effects. Hence, various approaches have been used to assess and control mycotoxin contamination. Significant challenges still exist because of the complex heterogeneous nature of food composition. The potential of combined omics approaches such as metabolomics, genomics, transcriptomics, and proteomics would contribute to our understanding about pathogen fungal crosstalk as well as strengthen our ability to identify, isolate, and characterise mycotoxins pre and post-harvest. Multi-omics approaches along with advanced analytical tools and chemometrics provide a complete annotation of such metabolites produced before/during the contamination of crops. We have assessed the merits of these individual and combined omics approaches and their promising applications to mitigate the issue of mycotoxin contamination. The data included in this review focus on aflatoxin, ochratoxin, and patulin and would be useful as benchmark information for future research.

Identification of differentially expressed genes involved in spore germination of Penicillium expansum by comparative transcriptome and proteome approaches

In this study, Penicillium expansum, a common destructive phytopathogen and patulin producer was isolated from naturally infected apple fruits and identified by morphological observation and rDNA-internal transcribed spacer analysis. Subsequently, a global view of the transcriptome and proteome alteration of P. expansum spores during germination was evaluated by RNA-seq (RNA sequencing) and iTRAQ (isobaric tags for relative and absolute quantitation) approaches. A total of 3,026 differentially expressed genes (DEGs), 77 differentially expressed predicted transcription factors and 489 differentially expressed proteins (DEPs) were identified. The next step involved screening out 130 overlapped candidates through correlation analysis between the RNA-seq and iTRAQ datasets. Part of them showed a different expression trend in the mRNA and protein levels, and most of them were involved in metabolism and genetic information processing. These results not only highlighted a set of genes and proteins that were important in deciphering the molecular processes of P. expansum germination but also laid the foundation to develop effective control methods and adequate environmental conditions.

Effect of Cinnamaldehyde and Citral Combination on Transcriptional Profile, Growth, Oxidative Damage and Patulin Biosynthesis of Penicillium expansum

Penicillium expansum, as a main postharvest pathogen of fruits, can secrete patulin (PAT), causing fruit decay and health problems. In this study, the antifungal test, SEM (scanning electron microscope) observation, transcriptional profile, PAT biosynthesis, and physiological characters of P. expansum exposed to cinnamaldehyde and citral combination (Cin/Cit) were evaluated. Cin/Cit could inhibit the mycelial growth and spore germination of P. expansum in a dose-dependent manner. Besides, Cin/Cit caused spores and mycelia wrinkled and depressed by SEM observation. Gene expression profiles of P. expansum were conducted by RNA sequencing (RNA-seq) in the presence or absence of Cin/Cit treatment. A total of 1713 differentially expressed genes (DEGs) were obtained, including 793 down-regulated and 920 up-regulated genes. Most of the DEGs participated in the biosynthesis of secondary metabolites, amino acid metabolism, and oxidation-reduction process, etc. Cin/Cit induced the dysfunction of the mitochondrial membrane, causing the potential influence on energy metabolism and reactive oxidative species production. The changes of superoxide dismutase (SOD) and catalase (CAT) activities combing with the increase of hydrogen peroxide content indicated the oxidative stress on P. expansum induced by Cin/Cit, which corresponded well with the transcriptional results. Moreover, both the RNA-seq data and the qRT-PCR showed the remarkable down-regulation of genes included in the PAT biosynthetic pathway under the Cin/Cit treatment. These findings provided more useful information about the antifungal mechanism of Cin/Cit against P. expansum at molecular and gene levels and suggested that Cin/Cit is a potential candidate to control P. expansum.

Antifungal mechanism of cinnamaldehyde and citral combination against Penicillium expansum based on FT-IR fingerprint, plasma membrane, oxidative stress and volatile profile

Cinnamaldehyde (Cin) and citral (Cit) have been studied as antimicrobial agents and natural preservatives, but their action modes are controversial, and the knowledge of their antifungal mechanism against P. expansum is still incomplete.