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Yang C, Wu D, Lin H, Ma D, Fu W, Yao Y, Pan X, Wang S, Zhuang Z. Role of RNA Modifications, Especially m6A, in Aflatoxin Biosynthesis of Aspergillus flavus. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:726-741. [PMID: 38112282 DOI: 10.1021/acs.jafc.3c05926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2023]
Abstract
RNA modifications play key roles in eukaryotes, but the functions in Aspergillus flavus are still unknown. Temperature has been reported previously to be a critical environmental factor that regulates the aflatoxin production of A. flavus, but much remains to be learned about the molecular networks. Here, we demonstrated that 12 kinds of RNA modifications in A. flavus were significantly changed under 29 °C compared to 37 °C incubation; among them, m6A was further verified by a colorimetric method. Then, the transcriptome-wide m6A methylome and m6A-altered genes were comprehensively illuminated through methylated RNA immunoprecipitation sequencing and RNA sequencing, from which 22 differentially methylated and expressed transcripts under 29 °C were screened out. It is especially notable that AFCA_009549, an aflatoxin biosynthetic pathway gene (aflQ), and the m6A methylation of its 332nd adenine in the mRNA significantly affect aflatoxin biosynthesis in A. flavus both on media and crop kernels. The content of sterigmatocystin in both ΔaflQ and aflQA332C strains was significantly higher than that in the WT strain. Together, these findings reveal that RNA modifications are associated with secondary metabolite biosynthesis of A. flavus.
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Affiliation(s)
- Chi Yang
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, Proteomic Research Center, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
- Institute of Edible Mushroom, Fujian Academy of Agricultural Sciences, Fuzhou 350012, China
| | - Dandan Wu
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, Proteomic Research Center, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Hong Lin
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, Proteomic Research Center, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Dongmei Ma
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, Proteomic Research Center, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
- College of Animal Sciences (College of Bee Science), Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Wangzhuo Fu
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, Proteomic Research Center, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Yanfang Yao
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, Proteomic Research Center, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Xiaohua Pan
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, Proteomic Research Center, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Shihua Wang
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, Proteomic Research Center, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Zhenhong Zhuang
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, Proteomic Research Center, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
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2
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Liang L, Wang X, Lan H, Wei S, Lei Y, Zhang S, Zhai H, Hu Y, Lv Y. Comprehensive analysis of aflatoxin B 1 biosynthesis in Aspergillus flavus via transcriptome-wide m 6A methylome response to cycloleucine. JOURNAL OF HAZARDOUS MATERIALS 2024; 461:132677. [PMID: 37797576 DOI: 10.1016/j.jhazmat.2023.132677] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 09/22/2023] [Accepted: 09/28/2023] [Indexed: 10/07/2023]
Abstract
Aspergillus flavus and its toxic aflatoxins secondary metabolites contaminate food and grains, posing a severe threat to human health and leading to liver cancer. Here, we demonstrated that cycloleucine blocked aflatoxin B1 synthesis by inhibiting N6-methyladenosine (m6A) methylation modification of messenger RNA (mRNA). m6A Methylation Immunoprecipitation Sequencing (m6A MeRIP-Seq)-based comprehensive transcriptome-wide m6A profiling identified 102 differentially expressed genes that underwent m6A modification, of which 22 hypermethylated genes were downregulated and 49 hypomethylated genes were upregulated, suggesting a negative correlation between m6A methylation and gene expression. Notably, cycloleucine inhibited aflatoxin B1 production via multiple targets. The m6A sites of several key genes involved in the aflatoxin B1 biosynthesis pathway were significantly enriched in the coding sequence and around the stop codon, resulting in their downregulation. Furthermore, m6A methylation on genes related to the aflatoxin B1 biosynthesis pathway led to reduced mRNA stability. Cycloleucine inhibition of aflatoxin B1 production highlights its potential as an agent for removing mycotoxins in environmental pollution. ENVIRONMENTAL IMPLICATION: Aflatoxins, highly carcinogenic secondary metabolites produced by Aspergillus flavus, frequently contaminate crops such as peanut, corn, wheat and sesame leading to irreversible loss in the quality and yield of agricultural products and posing serious threats to food safety. Aflatoxins has also been linked to developmental delays and liver cancer in humans. In our study, 'monitoring aflatoxin concentrations and its bioaccumulation in organisms' has been conducted. The results demonstrated that aflatoxin production in A. flavus was completely blocked after cycloleucine treatment. Additionally, we demonstrated that inhibition of aflatoxin was linked to N6-methyladenosine methylation of multiple genes in aflatoxin biosynthesis pathway.
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Affiliation(s)
- Liuke Liang
- College of biological engineering, Henan University of Technology, Zhengzhou 450001, China
| | - Xiaoyan Wang
- College of biological engineering, Henan University of Technology, Zhengzhou 450001, China
| | - Haier Lan
- College of biological engineering, Henan University of Technology, Zhengzhou 450001, China
| | - Shan Wei
- College of biological engineering, Henan University of Technology, Zhengzhou 450001, China
| | - Yang Lei
- College of biological engineering, Henan University of Technology, Zhengzhou 450001, China
| | - Shuaibing Zhang
- College of biological engineering, Henan University of Technology, Zhengzhou 450001, China
| | - Huanchen Zhai
- College of biological engineering, Henan University of Technology, Zhengzhou 450001, China
| | - Yuansen Hu
- College of biological engineering, Henan University of Technology, Zhengzhou 450001, China
| | - Yangyong Lv
- College of biological engineering, Henan University of Technology, Zhengzhou 450001, China.
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3
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Chen Z, Lin H, Wang F, Adade SYSS, Peng T, Chen Q. Discrimination of toxigenic and non-toxigenic Aspergillus flavus in wheat based on nanocomposite colorimetric sensor array. Food Chem 2024; 430:137048. [PMID: 37544158 DOI: 10.1016/j.foodchem.2023.137048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 07/18/2023] [Accepted: 07/27/2023] [Indexed: 08/08/2023]
Abstract
A novel method was developed for the early detection of wheat infected with Aspergillus flavus (A. flavus) using a nanocomposite colorimetric sensors array (CSA). LC-MS analysis revealed the presence of Aflatoxin B1 (AFB1) and Aflatoxin B2 (AFB2) on day seven, demonstrating mycotoxin variabilities in infected wheat. HS-SPME-GC-MS analysis detected 2-methylbutyral, a gas exclusively associated with toxigenic A. flavus. The CSA was modified using three nanoparticles of MOF and successfully used to detect the wheat infected with A. flavus. Discrimination of different types of infected wheat samples was achieved using the RGB difference map and Principal Component Analysis (PCA) model. Additionally, the Linear Discriminant Analysis (LDA) model accurately predicted the presence of toxigenic A. flavus at various stages of infection. These findings highlight the promising capabilities of nanocomposite CSA for early-stage detection of A. flavus infection in wheat.
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Affiliation(s)
- Zeyu Chen
- School of Food and Biological Engineering, Jiangsu University, No. 301 Xuefu Road, Jiangsu 212013, PR China
| | - Hao Lin
- School of Food and Biological Engineering, Jiangsu University, No. 301 Xuefu Road, Jiangsu 212013, PR China.
| | - Fuyun Wang
- School of Food and Biological Engineering, Jiangsu University, No. 301 Xuefu Road, Jiangsu 212013, PR China
| | | | - Tingting Peng
- School of Food and Biological Engineering, Jiangsu University, No. 301 Xuefu Road, Jiangsu 212013, PR China
| | - Quansheng Chen
- School of Food and Biological Engineering, Jiangsu University, No. 301 Xuefu Road, Jiangsu 212013, PR China; College of Food and Biological Engineering, Jimei University, Xiamen 361021, PR China.
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4
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Al-Zaban MI, Alrokban AH, Mahmoud MA. Development of a real-time PCR and multiplex PCR assay for the detection and identification of mycotoxigenic fungi in stored maize grains. Mycology 2023; 14:227-238. [PMID: 37583456 PMCID: PMC10424615 DOI: 10.1080/21501203.2023.2213704] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 05/09/2023] [Indexed: 08/17/2023] Open
Abstract
This study aimed to identify important mycotoxigenic fungi and accurate detection of mycotoxin in stored maize grains using molecular methods. The current study also optimised the real-time PCR (RT-PCR) assay. The melting curve was established to identify isolated fungal species of Aspergillus (4), Fusarium (3), Penicillium (3), and Alternaria (one). A multiplex polymerase chain reaction (mPCR) technique was developed for the detection and characterisation of mycotoxin producing fungi, mycotoxin metabolic pathway genes, and the determination of eleven mycotoxins in stored maize grains using high-performance liquid chromatography (HPLC). The mPCR results indicated positive signals for potentially mycotoxigenic fungal species tested of Aspergillus, Fusarium, Penicillium, and Alternaria. A protocol for multiplex reverse transcription-polymerase chain reaction (mRT-PCR) was tested to distinguish between free and contaminated, stored maize with aflatoxin B1 (AFB1). The expression pattern of four aflatoxin biosynthetic pathway genes, AFB1 (aflQ, aflP, aflO, and aflD), was a good marker for contaminated, stored maize grains. HPLC analysis showed that maize grain samples were contaminated with mycotoxins, and the concentration was above the detection level. The results indicate that the polyphasic approach might provide a sensitive, rapid, and accurate method for detecting and identifying mycotoxigenic fungal species and mycotoxins in stored maize grains.
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Affiliation(s)
- Mayasar I. Al-Zaban
- Department of Biology, College of Science, Princess Nourah Bint Abdulrahman University, Riyadh, Saudi Arabia
| | - Ahlam H. Alrokban
- Department of Biology, College of Science, Princess Nourah Bint Abdulrahman University, Riyadh, Saudi Arabia
| | - Mohamed A. Mahmoud
- Central Laboratory of Biotechnology (CLB), Plant Pathology Research Institute, Agricultural Research Center, Giza, Egypt
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Wang J, Liang L, Wei S, Zhang S, Hu Y, Lv Y. Histone 2-Hydroxyisobutyryltransferase Encoded by Afngg1 Is Involved in Pathogenicity and Aflatoxin Biosynthesis in Aspergillus flavus. Toxins (Basel) 2022; 15:7. [PMID: 36668827 PMCID: PMC9861817 DOI: 10.3390/toxins15010007] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 12/07/2022] [Accepted: 12/16/2022] [Indexed: 12/24/2022] Open
Abstract
Aflatoxin, a carcinogenic secondary metabolite produced by Aspergillus flavus, is a significant threat to human health and agricultural production. Histone 2-hydroxyisobutyrylation is a novel post-translational modification that regulates various biological processes, including secondary metabolism. In this study, we identified the novel histone 2-hydroxyisobutyryltransferase Afngg1 in A. flavus, and explored its role in cell growth, development and aflatoxin biosynthesis. Afngg1 gene deletion markedly decreased lysine 2-hydroxyisobutyrylation modification of histones H4K5 and H4K8 compared with the control strain. Additionally, Afngg1 deletion inhibited mycelial growth of A. flavus, and the number of conidia and hydrophobicity were significantly decreased. Notably, aflatoxin B1 biosynthesis and sclerotia production were completely inhibited in the ΔAfngg1 strain. Furthermore, the pathogenicity of the ΔAfngg1 strain infecting peanut and corn grains was also diminished, including reduced spore production and aflatoxin biosynthesis compared with A. flavus control and Afngg1 complementation strains. Transcriptome analysis showed that, compared with control strains, differentially expressed genes in ΔAfngg1 were mainly involved in chromatin remodelling, cell development, secondary metabolism and oxidative stress. These results suggest that Afngg1 is involved in histone 2-hydroxyisobutyrylation and chromatin modification, and thus affects cell development and aflatoxin biosynthesis in A. flavus. Our results lay a foundation for in-depth research on the 2-hydroxyisobutyrylation modification in A. flavus, and may provide a novel target for aflatoxin contamination prevention.
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Affiliation(s)
- Jing Wang
- College of Biological Engineering, Henan University of Technology, Zhengzhou 450001, China
- Henan Provincial Key Laboratory of Biological Processing and Nutritional Function of Wheat, Zhengzhou 450001, China
| | - Liuke Liang
- College of Biological Engineering, Henan University of Technology, Zhengzhou 450001, China
- Henan Provincial Key Laboratory of Biological Processing and Nutritional Function of Wheat, Zhengzhou 450001, China
| | - Shan Wei
- College of Biological Engineering, Henan University of Technology, Zhengzhou 450001, China
- Henan Provincial Key Laboratory of Biological Processing and Nutritional Function of Wheat, Zhengzhou 450001, China
| | - Shuaibing Zhang
- College of Biological Engineering, Henan University of Technology, Zhengzhou 450001, China
- Henan Provincial Key Laboratory of Biological Processing and Nutritional Function of Wheat, Zhengzhou 450001, China
| | - Yuansen Hu
- College of Biological Engineering, Henan University of Technology, Zhengzhou 450001, China
- Henan Provincial Key Laboratory of Biological Processing and Nutritional Function of Wheat, Zhengzhou 450001, China
| | - Yangyong Lv
- College of Biological Engineering, Henan University of Technology, Zhengzhou 450001, China
- Henan Provincial Key Laboratory of Biological Processing and Nutritional Function of Wheat, Zhengzhou 450001, China
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Liang L, Yang H, Wei S, Zhang S, Chen L, Hu Y, Lv Y. Putative C 2H 2 Transcription Factor AflZKS3 Regulates Aflatoxin and Pathogenicity in Aspergillus flavus. Toxins (Basel) 2022; 14:toxins14120883. [PMID: 36548780 PMCID: PMC9786134 DOI: 10.3390/toxins14120883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2022] [Revised: 12/14/2022] [Accepted: 12/15/2022] [Indexed: 12/23/2022] Open
Abstract
Aflatoxin is a carcinogenic secondary metabolite that poses a serious threat to human and animal health. Some C2H2 transcription factors are associated with fungal growth and secondary metabolic regulation. In this study, we characterized the role of AflZKS3, a putative C2H2 transcription factor based on genome annotation, in the growth and aflatoxin biosynthesis of A. flavus and explored its possible mechanisms of action. Surprisingly, the protein was found to be located in the cytoplasm, and gene deletion in A. flavus resulted in defective growth and conidia formation, as well as increased sensitivity to the fluorescent brightener Calcofluor white, Congo red, NaCl, and sorbitol stress. Notably, the biosynthesis of aflatoxin B1 was completely inhibited in the ΔAflZKS3 deletion strain, and its ability to infect peanut and corn seeds was also reduced. RNA sequencing showed that differentially expressed genes in the ΔAflZKS3 strain compared with the control and complementation strains were mainly associated with growth, aflatoxin biosynthesis, and oxidative stress. Thus, AflZKS3 likely contributes to growth, cell development, and aflatoxin synthesis in A. flavus. These findings lay the foundation for a deeper understanding of the roles of C2H2 transcription factors in A. flavus and provide a potential biocontrol target for preventing aflatoxin contamination.
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Maximizing Laboratory Production of Aflatoxins and Fumonisins for Use in Experimental Animal Feeds. Microorganisms 2022; 10:microorganisms10122385. [PMID: 36557638 PMCID: PMC9786054 DOI: 10.3390/microorganisms10122385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 11/24/2022] [Accepted: 11/29/2022] [Indexed: 12/03/2022] Open
Abstract
Warm and humid climatic conditions coupled with poor agricultural practices in sub-Saharan Africa favor the contamination of food and feed by Aspergillus flavus and Fusarium verticillioides fungi, which subsequently may produce aflatoxins (AFs) and fumonisins (FBs), respectively. The growth of fungi and the production of mycotoxins are influenced by physical (temperature, pH, water activity, light and aeration), nutritional, and biological factors. This study aimed at optimizing the conditions for the laboratory production of large quantities of AFs and FBs for use in the animal experiments. A. flavus and F. verticillioides strains, previously isolated from maize in Kenya, were used. Levels of AFB1 and total FBs (FB1, FB2, and FB3) in different growth substrates were screened using ELISA methods. Maize kernels inoculated with three different strains of A. flavus simultaneously and incubated at 29 °C for 21 days had the highest AFB1 level of 12,550 ± 3397 μg/kg of substrate. The highest level of total FBs (386,533 ± 153,302 μg/kg of substrate) was detected in cracked maize inoculated with three different strains of F. verticillioides and incubated for 21 days at temperatures of 22-25 °C in a growth chamber fitted with yellow light. These two methods are recommended for the mass production of AFB1 and FBs for animal feeding trials.
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Reis T, Tralamazza S, Coelho E, Zorzete P, Corrêa B. Early expression of the aflatoxin gene cluster in Aspergillus nomiae isolated from Brazil nut. Toxicon 2022; 209:36-42. [DOI: 10.1016/j.toxicon.2022.01.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 12/30/2021] [Accepted: 01/21/2022] [Indexed: 10/19/2022]
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Schamann A, Schmidt-Heydt M, Geisen R. Analysis of the competitiveness between a non-aflatoxigenic and an aflatoxigenic Aspergillus flavus strain on maize kernels by droplet digital PCR. Mycotoxin Res 2021; 38:27-36. [PMID: 34913138 PMCID: PMC8816369 DOI: 10.1007/s12550-021-00447-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 11/12/2021] [Accepted: 12/01/2021] [Indexed: 11/26/2022]
Abstract
Non-aflatoxigenic Aspergillus flavus strains are used as a biocontrol system on maize fields to decrease the aflatoxin biosynthesis of aflatoxigenic A. flavus strains. A. flavus strain AF36 was the first commercially available biocontrol strain and is authorized for use on maize fields by the US Environmental Protection Agency, e.g., in Texas and Arizona. A droplet digital PCR (ddPCR) assay was developed to analyze the mechanisms of competition and interaction of aflatoxigenic and non-aflatoxigenic A. flavus strains. This assay enables the parallel identification and quantification of the biocontrol strain A. flavus AF36 and the aflatoxigenic A. flavus strain MRI19. To test the assay, spores of both strains were mixed in varying ratios and were incubated on maize-based agar or maize kernels for up to 20 days. Genomic equivalent ratios (genome copy numbers) of both strains were determined by ddPCR at certain times after incubation and were compared to the spore ratios used for inoculation. The aflatoxin biosynthesis was also measured. In general, A. flavus MRI19 had higher competitiveness in the tested habitats compared to the non-aflatoxigenic strain, as indicated by higher final genomic equivalent ratios of this strain compared to the spore ratios used for inoculation. Nevertheless, A. flavus AF36 effectively controlled aflatoxin biosynthesis of A. flavus MRI19, as a clear aflatoxin inhibition was already seen by the inoculation of 10% spores of the biocontrol strain mixed with 90% spores of the aflatoxigenic strain compared to samples inoculated with only spores of the aflatoxigenic A. flavus MRI19.
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Affiliation(s)
- Alexandra Schamann
- Department of Safety and Quality of Fruit and Vegetables, Max Rubner-Institut (MRI) - Federal Research Institute of Nutrition and Food, Karlsruhe, Germany
| | - Markus Schmidt-Heydt
- Department of Safety and Quality of Fruit and Vegetables, Max Rubner-Institut (MRI) - Federal Research Institute of Nutrition and Food, Karlsruhe, Germany.
| | - Rolf Geisen
- Department of Safety and Quality of Fruit and Vegetables, Max Rubner-Institut (MRI) - Federal Research Institute of Nutrition and Food, Karlsruhe, Germany
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Li T, Zhang Z, Wang Y, Li Y, Zhu J, Hu R, Yang Y, Liu M. Quantitative Proteomic Analysis for High- and Low-Aflatoxin-Yield Aspergillus flavus Strains Isolated From Natural Environments. Front Microbiol 2021; 12:741875. [PMID: 34621259 PMCID: PMC8491651 DOI: 10.3389/fmicb.2021.741875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 09/01/2021] [Indexed: 11/13/2022] Open
Abstract
The molecular mechanisms underlying aflatoxin production have been well-studied in strains of the fungus Aspergillus flavus (A. flavus) under artificial conditions. However, aflatoxin biosynthesis has rarely been studied in A. flavus strains isolated from field conditions with different aflatoxin-producing ability. In the present study, tandem mass tag (TMT) labeling and high-performance liquid chromatography (HPLC) coupled with tandem-mass spectrometry analysis were used for proteomic quantification in natural isolates of high- and low-aflatoxin-yield A. flavus strains. Additionally, findings obtained using the TMT-labeling method were validated using the high-resolution multiple reaction monitoring (MRM-HR) method. In total, 4,363 proteins were quantified, among which 1,045 proteins were differentially expressed between the high- and low-aflatoxin-yield A. flavus strains. Bioinformatics analysis showed that the up-regulated proteins were significantly enriched in carbon-related metabolism and the biosynthesis of secondary metabolites, whereas the down-regulated proteins were enriched in oxidative phosphorylation. Moreover, GST proteins were found to be significantly down-regulated in high-yield A. flavus strains; this result contradicted previous findings obtained from A. flavus strains grown under artificial conditions. In summary, our study provides novel insights into aflatoxin regulation in A. flavus under field conditions and could facilitate the development of various strategies for the effective control of aflatoxin contamination in food crops.
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Affiliation(s)
- Tao Li
- State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan National Laboratory for Optoelectronics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Huazhong University of Science and Technology, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Zhaowei Zhang
- Chinese Academy of Agricultural Sciences, Wuhan, China
| | - Yu Wang
- State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan National Laboratory for Optoelectronics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Huazhong University of Science and Technology, Wuhan, China
| | - Ying Li
- State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan National Laboratory for Optoelectronics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Huazhong University of Science and Technology, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Jiang Zhu
- State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan National Laboratory for Optoelectronics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Huazhong University of Science and Technology, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Rui Hu
- State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan National Laboratory for Optoelectronics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Huazhong University of Science and Technology, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Yunhuang Yang
- State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan National Laboratory for Optoelectronics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Huazhong University of Science and Technology, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Maili Liu
- State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan National Laboratory for Optoelectronics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Huazhong University of Science and Technology, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
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Archer M, Xu J. Current Practices for Reference Gene Selection in RT-qPCR of Aspergillus: Outlook and Recommendations for the Future. Genes (Basel) 2021; 12:genes12070960. [PMID: 34202507 PMCID: PMC8307107 DOI: 10.3390/genes12070960] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 06/20/2021] [Accepted: 06/21/2021] [Indexed: 12/21/2022] Open
Abstract
Aspergillus is a genus of filamentous fungi with vast geographic and ecological distributions. Species within this genus are clinically, agriculturally and biotechnologically relevant, leading to increasing interest in elucidating gene expression dynamics of key metabolic and physiological processes. Reverse-transcription quantitative Polymerase Chain Reaction (RT-qPCR) is a sensitive and specific method of quantifying gene expression. A crucial step for comparing RT-qPCR results between strains and experimental conditions is normalisation to experimentally validated reference gene(s). In this review, we provide a critical analysis of current reference gene selection and validation practices for RT-qPCR gene expression analyses of Aspergillus. Of 90 primary research articles obtained through our PubMed query, 17 experimentally validated the reference gene(s) used. Twenty reference genes were used across the 90 studies, with beta-tubulin being the most used reference gene, followed by actin, 18S rRNA and glyceraldehyde 3-phosphate dehydrogenase. Sixteen of the 90 studies used multiple reference genes for normalisation. Failing to experimentally validate the stability of reference genes can lead to conflicting results, as was the case for four studies. Overall, our review highlights the need to experimentally validate reference genes in RT-qPCR studies of Aspergillus.
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Affiliation(s)
| | - Jianping Xu
- Correspondence: ; Tel.: +1-905-525-9140 (ext. 27934); Fax: +1-905-522-6066
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12
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Abd El-Aziz AR, Shehata SM, Hisham SM, Alobathani AA. Molecular profile of aflatoxigenic and non-aflatoxigenic isolates of Aspergillus flavus isolated from stored maize. Saudi J Biol Sci 2021; 28:1383-1391. [PMID: 33613068 PMCID: PMC7878702 DOI: 10.1016/j.sjbs.2020.11.073] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 11/18/2020] [Accepted: 11/24/2020] [Indexed: 12/02/2022] Open
Abstract
Maize is a significant staple crop and utilized in Saudi Arabia as food and feed, but maize is often infected with Aspergillus flavus in tropical and subtropical climates, especially during storage. This study intended at a polyphasic approach, consisting of microscopic morphological, biochemical, and molecular characterizations that were applied to 29 of A. flavus isolates of stored maize, with the goal of characterization and identification of aflatoxigenic and non-aflatoxigenic A. flavus isolates. The technique of real-time PCR (RTi-PCR) was used to detection of A. flavus in stored maize samples, the findings have been very accurate. Centered on macroscopic morphological (primarily colony color and morphology of conidia) and microscopic (morphology of conidia and size) characteristics. Results have shown 23 A. flavus isolates (80%) were categorized as the dark green of colonies also all isolates were rough conidia. The isolates have been two different groups, 16 isolates (62%) had sclerotium-forming and the remaining 13 isolates (38%) had no sclerotium-forming isolates. To the identification of aflatoxigenic isolates of A. flavus in stored maize, we utilized the qualitative methods (easy and inexpensive) like UV test, yellow pigmentation, and ammonia vapor and quantitative method as HPLC (accurate and expensive). the accuracy methods to the identification aflatoxigenicity isolates, vary, and classified in the following descending order: HPLC (100%) > UV method (81%) > yellow pigmentation (YP) and ammonia vapor (AV) (63%). The profile of Aflatoxigenicity of A. flavus isolates by HPLC has been involved in two types first of 11 isolates (38%) have been aflatoxigenic isolates while 18 isolates (62%) were non-aflatoxigenic isolates. The expression of six aflatoxins (AFs) genes (aflD, aflM, aflO, aflP, aflR, and aflQ) was estimated using PCR and RT-PCR. PCR of all genes did not correspond to the aflatoxigenic isolates. The transcriptional analysis of aflO and aflQ was a beneficial marker for discriminating aflatoxigenic from non-aflatoxigenic A. flavus isolates. Also, qRT-PCR indicated that non-aflatoxigenic isolates had a high incidence of defect or downregulation in late AF-genes contrast with early AF-genes. therefore, these non-aflatoxigenic isolates could be critical factors for an efficient and competent strategy for the control of aflatoxin contamination pre-harvest can be considered.
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Affiliation(s)
- Abeer R.M. Abd El-Aziz
- Botany and Microbiology, Department, College of Science, King Saud University, Riyadh, Saudi Arabia
- Corresponding author.
| | - Shereen M. Shehata
- Pharmaceutical Chemistry Depart., College of Pharmacy, King Saud University, Riyadh, Saudi Arabia
| | - Sameh M. Hisham
- Botany and Microbiology, Department, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - Afnan A. Alobathani
- Botany and Microbiology, Department, College of Science, King Saud University, Riyadh, Saudi Arabia
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Sohrabi N, Taghizadeh M. Molecular identification of aflatoxigenic Aspergillus species in feedstuff samples. Curr Med Mycol 2018; 4:1-6. [PMID: 30324150 PMCID: PMC6181065 DOI: 10.18502/cmm.4.2.66] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Background and Purpose: Aflatoxins are naturally produced by some species of Aspergillus, such as A.flavus and A.parasiticus. Aflatoxins reportedly have carcinogenic effects on human, poultry, and livestock, and therefore could be linked to severe human illnesses. Aflatoxin biosynthesis pathway involves different clustered genes, including structural, regular, and unassigned genes. The present study was conducted to detect aflR,aflP, and aflD as three important genes contributing to aflatoxin B1 production cycle in Aspergillus species isolated from the feedstuffs of animal husbandry. Materials and Methods: This study was conducted on 25 isolates of A. flavus, A. parasiticus, A. nomius, and A. nidulans, isolated from animal feedstuff as a test group. The test group was compared with two standard strains (i.e., A. flavus and A. parasiticus) as aflatoxigenic reference organisms and negative controls (i.e., A. fumigatus, A.fusarium, and A.penicillium) in terms of the presence of aflR, aflP, and aflD genes using polymerase chain reaction (PCR). The determination of the toxigenicity and aflatoxin production of isolated Aspergillus species was accomplished using thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC). Results: The results obtained by the amplification of the selected genes by PCR method for the detection of aflatoxigenic Asprgillus species were significantly correlated with TLC and HPLC results. Accordingly, all samples, having positive results for aflatoxin B1 production in TLC and HPLC, were able to show the amplification of three target genes. However, 4 cases out of 6 (66%) non-aflatoxigenic isolates were positive for three or two genes. Conclusion: Based on the findings, the molecular detection of aflatoxin biosynthesis genes (i.e., aflP, aflD, and aflR) could be considered as a quick and reliable method for the detection of aflatoxigenic Aspergillus. Furthermore, this method could be useful in planning and implementing strategies targeted toward improving the safety of human or animal food.
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Affiliation(s)
| | - Morteza Taghizadeh
- Department of Research and Development, Razi Vaccine and Serum Research Institute, Agricultural Research Education and Extension Organization, Karaj, Iran
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Habibi N, Nassiri-Toosi M, Sharafi H, Alavian SM, Shams-Ghahfarokhi M, Razzaghi-Abyaneh M. Aflatoxin B1 exposure and the risk of hepatocellular carcinoma in Iranian carriers of viral hepatitis B and C. TOXIN REV 2018. [DOI: 10.1080/15569543.2018.1446027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Nasim Habibi
- Department of Mycology, Pasteur Institute of Iran, Tehran, Iran
- Department of Drug Quality Assurance, Pharmaceutical Sciences Branch, Islamic Azad University, Tehran, Iran
| | - Mohsen Nassiri-Toosi
- Liver Transplantation Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Heidar Sharafi
- Baqiyatallah Research Center for Gastroenterology and Liver Diseases, Baqiyatallah University of Medical Sciences, Tehran, Iran
- Middle East Liver Diseases (MELD) Center, Tehran, Iran
| | - Seyed Moayed Alavian
- Baqiyatallah Research Center for Gastroenterology and Liver Diseases, Baqiyatallah University of Medical Sciences, Tehran, Iran
- Middle East Liver Diseases (MELD) Center, Tehran, Iran
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Okoth S, De Boevre M, Vidal A, Diana Di Mavungu J, Landschoot S, Kyallo M, Njuguna J, Harvey J, De Saeger S. Genetic and Toxigenic Variability within Aspergillus flavus Population Isolated from Maize in Two Diverse Environments in Kenya. Front Microbiol 2018; 9:57. [PMID: 29434580 PMCID: PMC5790802 DOI: 10.3389/fmicb.2018.00057] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 01/10/2018] [Indexed: 12/18/2022] Open
Abstract
Aspergillus flavus is the main producer of carcinogenic aflatoxins in agricultural commodities such as maize. This fungus occurs naturally on crops, and produces aflatoxins when environmental conditions are favorable. The aim of this study is to analyse the genetic variability among 109 A. flavus isolates previously recovered from maize sampled from a known aflatoxin-hotspot (Eastern region, Kenya) and the major maize-growing area in the Rift Valley (Kenya), and to determine their toxigenic potential. DNA analyses of internal transcribed spacer (ITS) regions of ribosomal DNA, partial β-tubulin gene (benA) and calmodulin gene (CaM) sequences were used. The strains were further analyzed for the presence of four aflatoxin-biosynthesis genes in relation to their capability to produce aflatoxins and other metabolites, targeting the regulatory gene aflR and the structural genes aflP, aflD, and aflQ. In addition, the metabolic profile of the fungal strains was unraveled using state-of-the-art LC-MS/MS instrumentation. The three gene-sequence data grouped the isolates into two major clades, A. minisclerotigenes and A. flavus. A. minisclerotigenes was most prevalent in Eastern Kenya, while A. flavus was common in both regions. A. parasiticus was represented by a single isolate collected from Rift Valley. Diversity existed within the A. flavus population, which formed several subclades. An inconsistency in identification of some isolates using the three markers was observed. The calmodulin gene sequences showed wider variation of polymorphisms. The aflatoxin production pattern was not consistent with the presence of aflatoxigenic genes, suggesting an inability of the primers to always detect the genes or presence of genetic mutations. Significant variation was observed in toxin profiles of the isolates. This is the first time that a profound metabolic profiling of A. flavus isolates was done in Kenya. Positive associations were evident for some metabolites, while for others no associations were found and for a few metabolite-pairs negative associations were seen. Additionally, the growth medium influenced the mycotoxin metabolite production. These results confirm the wide variation that exists among the group A. flavus and the need for more insight in clustering the group.
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Affiliation(s)
- Sheila Okoth
- School of Biological Sciences, University of Nairobi, Nairobi, Kenya
| | - Marthe De Boevre
- Department of Bioanalysis, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium
| | - Arnau Vidal
- Department of Bioanalysis, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium
| | - José Diana Di Mavungu
- Department of Bioanalysis, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium
| | - Sofie Landschoot
- Department of Applied Bioscience Engineering, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Martina Kyallo
- Biosciences Eastern and Central Africa, International Livestock Research Institute, Nairobi, Kenya
| | - Joyce Njuguna
- Biosciences Eastern and Central Africa, International Livestock Research Institute, Nairobi, Kenya
| | - Jagger Harvey
- Feed the Future Innovation Lab, Kansas State University, Manhattan, KS, United States
| | - Sarah De Saeger
- Department of Bioanalysis, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium
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4-Hydroxy-7-methyl-3-phenylcoumarin Suppresses Aflatoxin Biosynthesis via Downregulation of aflK Expressing Versicolorin B Synthase in Aspergillus flavus. Molecules 2017; 22:molecules22050712. [PMID: 28468270 PMCID: PMC6154296 DOI: 10.3390/molecules22050712] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Revised: 04/26/2017] [Accepted: 04/27/2017] [Indexed: 11/22/2022] Open
Abstract
Naturally occurring coumarins possess antibacterial and antifungal properties. In this study, these natural and synthetic coumarins were used to evaluate their antifungal activities against Aspergillus flavus, which produces aflatoxins. In addition to control antifungal activities, antiaflatoxigenic properties were also determined using a high-performance liquid chromatography in conjunction with fluorescence detection. In this study, 38 compounds tested and 4-hydroxy-7-methyl-3-phenyl coumarin showed potent antifungal and antiaflatoxigenic activities against A. flavus. Inhibitory mode of antiaflatoxigenic action by 4-hydroxy-7-methyl-3-phenyl coumarin was based on the downregulation of aflD, aflK, aflQ, and aflR in aflatoxin biosynthesis. In the cases of coumarins, antifungal and aflatoxigenic activities are highly related to the lack of diene moieties in the structures. In structurally related compounds, 2,3-dihydrobenzofuran exhibited antifungal and antiaflatoxigenic activities against A. flavus. The inhibitory mode of antiaflatoxigenic action by 2,3-dihydrobenzofuran was based on the inhibition of the transcription factor (aflS) in the aflatoxin biosynthesis pathway. These potent inhibitions of 2,3-dihydrobenzofuran and 4-hydroxy-7-methyl-3-phenyl coumarin on the Aspergillus growth and production of aflatoxins contribute to the development of new controlling agents to mitigate aflatoxin contamination.
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17
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Evaluating Aflatoxin Gene Expression in Aspergillus Section Flavi. Methods Mol Biol 2016. [PMID: 27924542 DOI: 10.1007/978-1-4939-6707-0_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
The determination of aflatoxin production ability and differentiation of aflatoxigenic strains can be assessed by monitoring the expression of one or several key genes using reverse transcription polymerase chain reaction (RT-PCR). We herein describe the methods for RNA induction, extraction, and quality determination, and the RT-PCR conditions used to evaluate the ability of a given Aspergillus strain to produce aflatoxins.
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Baquião AC, Rodriges AG, Lopes EL, Tralamazza SM, Zorzete P, Correa B. Expression of Genes by Aflatoxigenic and Nonaflatoxigenic Strains of Aspergillus flavus Isolated from Brazil Nuts. Foodborne Pathog Dis 2016; 13:434-40. [PMID: 27224419 DOI: 10.1089/fpd.2015.2111] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The aims of the present study were to monitor the production of aflatoxin B1 (AFB1) and mycelial growth, and to evaluate the expression of genes directly and indirectly involved in the biosynthesis of aflatoxins by Aspergillus flavus isolated from Brazil nuts. Six previously identified A. flavus strains were grown on coconut agar at 25°C for up to 10 days. Mycotoxins were separated by high-performance liquid chromatography and fungal growth was measured daily using the diametric mycelial growth rate. Transcriptional analysis was performed by real-time polymerase chain reaction (PCR) after 2 and 7 d of incubation using specific primers (aflR, aflD, aflP, lipase, metalloprotease, and LaeA). Three (50%) of the six A. flavus isolates produced AFB1 (ICB-1, ICB-12, and ICB-54) and three (50%) were not aflatoxigenic (ICB-141, ICB-161, and ICB-198). Aflatoxin production was observed from d 2 of incubation (1.5 ng/g for ICB-54) and increased gradually with time of incubation until d 10 (15,803.6 ng/g for ICB-54). Almost all A. flavus isolates exhibited a similar gene expression pattern after 2 d of incubation (p > 0.10). After 7 d of incubation, the LaeA (p < 0.05) and metalloprotease (p < 0.05) genes were the most expressed by nonaflatoxigenic strains, whereas aflatoxigenic isolates exhibited higher expression of the aflR (p < 0.05) and aflD genes (p < 0.05). Our results suggest that the expression of aflR and aflD is correlated with aflatoxin production in A. flavus and that overexpression of aflR could affect the transcriptional and aflatoxigenic pattern (ICB-54). Elucidation of the molecular mechanisms that regulate the secondary metabolism of toxigenic fungi may permit the rational silencing of the genes involved and consequently the programmed inhibition of aflatoxin production. Knowledge of the conditions, under which aflatoxin genes are expressed, should contribute to the development of innovative and more cost-effective strategies to reduce and prevent aflatoxin contamination in Brazil nuts.
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Affiliation(s)
- Arianne Costa Baquião
- 1 Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo , São Paulo, Brazil
| | - Aline Guedes Rodriges
- 1 Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo , São Paulo, Brazil
| | - Evandro Luiz Lopes
- 2 Escola Paulista de Política, Economia e Negócios, Universidade Federal de São Paulo , São Paulo, Brazil
| | - Sabina Moser Tralamazza
- 1 Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo , São Paulo, Brazil
| | - Patricia Zorzete
- 1 Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo , São Paulo, Brazil
| | - Benedito Correa
- 1 Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo , São Paulo, Brazil
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Mahmoud MA. Detection of Aspergillus flavus in stored peanuts using real-time PCR and the expression of aflatoxin genes in toxigenic and atoxigenic A. flavus isolates. Foodborne Pathog Dis 2015; 12:289-96. [PMID: 25621617 DOI: 10.1089/fpd.2014.1854] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Aspergillus flavus is the main species from section Flavi responsible for aflatoxin accumulation in stored peanuts. Rapid methods to detect A. flavus could help to prevent aflatoxins from entering the food chain. A real-time polymerase chain reaction (RTi-PCR) assay was standardized for rapid, specific, and sensitive detection of A. flavus in stored peanuts. A. flavus was detected in 53.6% and 50% of peanut samples by RTi-PCR and A. flavus and Aspergillus parasiticus agar culture, respectively, with 95% agreement between them. Twenty-two A. flavus isolates were screened using high-performance liquid chromatography for their capacity to produce aflatoxin AFB1 (B1). B1 was produced by >72% of the isolates. Sixteen isolates produced B1 at concentrations ranging from 1.64 to 109.18 μg/mL. Four aflatoxin biosynthetic pathway genes (aflD, aflM, aflP, and aflQ) were evaluated using PCR and reverse-transcription PCR in 22 A. flavus isolates from peanut kernels with the aim of rapidly and accurately differentiating toxigenic and atoxigenic isolates. The PCR amplification of genes did not correlate with aflatoxin production capability. The expression of aflD and aflQ was a good marker for differentiating toxigenic from atoxigenic isolates.
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Affiliation(s)
- Mohamed A Mahmoud
- Plant Pathology Research Institute, Agricultural Research Center , Giza, Egypt
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Zhang F, Guo Z, Zhong H, Wang S, Yang W, Liu Y, Wang S. RNA-Seq-based transcriptome analysis of aflatoxigenic Aspergillus flavus in response to water activity. Toxins (Basel) 2014; 6:3187-207. [PMID: 25421810 PMCID: PMC4247253 DOI: 10.3390/toxins6113187] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Revised: 10/27/2014] [Accepted: 11/13/2014] [Indexed: 01/06/2023] Open
Abstract
Aspergillus flavus is one of the most important producers of carcinogenic aflatoxins in crops, and the effect of water activity (aw) on growth and aflatoxin production of A. flavus has been previously studied. Here we found the strains under 0.93 aw exhibited decreased conidiation and aflatoxin biosynthesis compared to that under 0.99 aw. When RNA-Seq was used to delineate gene expression profile under different water activities, 23,320 non-redundant unigenes, with an average length of 1297 bp, were yielded. By database comparisons, 19,838 unigenes were matched well (e-value < 10−5) with known gene sequences, and another 6767 novel unigenes were obtained by comparison to the current genome annotation of A. flavus. Based on the RPKM equation, 5362 differentially expressed unigenes (with |log2Ratio| ≥ 1) were identified between 0.99 aw and 0.93 aw treatments, including 3156 up-regulated and 2206 down-regulated unigenes, suggesting that A. flavus underwent an extensive transcriptome response during water activity variation. Furthermore, we found that the expression of 16 aflatoxin producing-related genes decreased obviously when water activity decreased, and the expression of 11 development-related genes increased after 0.99 aw treatment. Our data corroborate a model where water activity affects aflatoxin biosynthesis through increasing the expression of aflatoxin producing-related genes and regulating development-related genes.
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Affiliation(s)
- Feng Zhang
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of the Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Zhenni Guo
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of the Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Hong Zhong
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of the Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Sen Wang
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of the Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Weiqiang Yang
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of the Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Yongfeng Liu
- Shenzhen Key Laboratory of Bioenergy, BGI-Shenzhen, Shenzhen 518083, China.
| | - Shihua Wang
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of the Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
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