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Son YE, Park HS. SscA is required for fungal development, aflatoxin production, and pathogenicity in Aspergillus flavus. Int J Food Microbiol 2024; 413:110607. [PMID: 38308877 DOI: 10.1016/j.ijfoodmicro.2024.110607] [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: 12/14/2023] [Revised: 01/16/2024] [Accepted: 01/23/2024] [Indexed: 02/05/2024]
Abstract
Fungal spores are specialized dormant cells that act as primary reproductive biological particles and exhibit strong viability under extremely harsh conditions. They contaminate a variety of crops and foods, causing severe health hazards to humans and animals. Previous studies demonstrated that a spore-specific transcription factor SscA plays pivotal roles in the conidiogenesis of the model organism Aspergillus nidulans. In this study, we investigated the biological and genetic functions of SscA in the aflatoxin-producing fungus A. flavus. Deletion of sscA showed reduced conidia formation, lost long-term viability, and exhibited more sensitivity to thermal, oxidative, and radiative stresses. The sscA-deficient strain showed increased aflatoxin B1 production in conidia as well as mycelia. Importantly, the absence of sscA affected fungal pathogenicity on crops. Further transcriptomic and phenotypic studies suggested that SscA coordinates conidial wall structures. Overall, SscA is important for conidial formation, maturation and dormancy, mycotoxin production, and pathogenicity in A. flavus.
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Affiliation(s)
- Ye-Eun Son
- School of Food Science and Biotechnology, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Hee-Soo Park
- School of Food Science and Biotechnology, Kyungpook National University, Daegu 41566, Republic of Korea; Department of Integrative Biology, Kyungpook National University, Daegu 41566, Republic of Korea.
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Liu L, Li L, Li F, Ma W, Guo W, Fang X. Role of Pmk1, Mpk1, or Hog1 in the mitogen-activated protein kinase pathway of Aspergillus cristatus. Fungal Genet Biol 2024; 171:103874. [PMID: 38307402 DOI: 10.1016/j.fgb.2024.103874] [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: 06/09/2023] [Revised: 01/04/2024] [Accepted: 01/22/2024] [Indexed: 02/04/2024]
Abstract
Aspergillus cristatus is a probiotic fungus known for its safety and abundant secondary metabolites, making it a promising candidate for various applications. However, limited progress has been made in researching A. cristatus due to challenges in genetic manipulation. The mitogen-activated protein kinase (MAPK) signaling pathway is involved in numerous physiological processes, but its specific role in A. cristatus remains unclear. In this study, we successfully developed an efficient polyethylene glycol (PEG)-mediated protoplast transformation method for A. cristatus, enabling us to investigate the function of Pmk1, Mpk1, and Hog1 in the MAPK signaling pathway. Our findings revealed that Pmk1, Mpk1, and Hog1 are crucial for sexual reproduction, melanin synthesis, and response to external stress in A. cristatus. Notably, the deletion of Pmk1, Mpk1, or Hog1 resulted in the loss of sexual reproduction capability in A. cristatus. Overall, this research on MAPK will contribute to the continued understanding of the reproductive strategy and melanin synthesis mechanism of A. cristatus.
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Affiliation(s)
- Lulu Liu
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 6266237, China
| | - Longyue Li
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 6266237, China
| | - Fengyi Li
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 6266237, China
| | - Wei Ma
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 6266237, China
| | - Wei Guo
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 6266237, China
| | - Xu Fang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 6266237, China; Rongcheng Huihai Chuangda Biotechnology Co., Ltd., Weihai, Shandong 264309, China.
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Kim JH, Chan KL, Hart-Cooper WM, Palumbo JD, Orts WJ. High-efficiency fungal pathogen intervention for seed protection: new utility of long-chain alkyl gallates as heat-sensitizing agents. FRONTIERS IN FUNGAL BIOLOGY 2023; 4:1172893. [PMID: 37746121 PMCID: PMC10512402 DOI: 10.3389/ffunb.2023.1172893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Accepted: 07/13/2023] [Indexed: 09/26/2023]
Abstract
Control of food-contaminating fungi, especially pathogens that produce mycotoxins, is problematic since effective method for intervening fungal infection on food crops is often limited. Generally Regarded As Safe (GRAS) chemicals, such as natural compounds or their structural derivatives, can be developed as antimicrobial agents for sustainable food/crop production. This study identified that long-chain alkyl gallates, i.e., octyl-, nonyl-, and decyl gallates (OG (octyl 3,4,5-trihydroxybenzoic acid), NG, DG), can function as heat-sensitizing agents that effectively prevent fungal contamination. Out of twenty-eight candidate compounds and six conventional antifungal agents examined, the heat-sensitizing capacity was unique to the long-chain alkyl gallates, where OG exhibited the highest activity, followed by DG and NG. Since OG is a GRAS compound classified by the United States Food and Drug Administration (FDA), further in vitro antifungal studies were performed using OG. When OG and mild heat (57.5°C) were co-administered for 90 seconds, the treatment achieved > 99.999% fungal death (> 5 log reduction). Application of either treatment alone was significantly less effective at reducing fungal survival. Of note, co-application of OG (3 mM) and mild heat (50°C) for 20 minutes completely prevented the survival of aflatoxigenic Aspergillus flavus contaminating crop seeds (Brassica rapa Pekinensis), while seed germination rate was unaffected. Heat-sensitization was also determined in selected bacterial strains (Escherichia coli, Agrobacterium tumefaciens). Altogether, OG is an effective heat-sensitizing agent for control of microbial pathogens. OG-mediated heat sensitization will improve the efficacy of antimicrobial practices, achieving safe, rapid, and cost-effective pathogen control in agriculture/food industry settings.
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Affiliation(s)
- Jong H. Kim
- Foodborne Toxin Detection and Prevention Research Unit, Western Regional Research Center, Agricultural Research Service, United States Department of Agriculture (USDA-ARS), Albany, CA, United States
| | - Kathleen L. Chan
- Foodborne Toxin Detection and Prevention Research Unit, Western Regional Research Center, Agricultural Research Service, United States Department of Agriculture (USDA-ARS), Albany, CA, United States
| | - William M. Hart-Cooper
- Bioproducts Research Unit, Western Regional Research Center, Agricultural Research Service, United States Department of Agriculture (USDA-ARS), Albany, CA, United States
| | - Jeffrey D. Palumbo
- Foodborne Toxin Detection and Prevention Research Unit, Western Regional Research Center, Agricultural Research Service, United States Department of Agriculture (USDA-ARS), Albany, CA, United States
| | - William J. Orts
- Bioproducts Research Unit, Western Regional Research Center, Agricultural Research Service, United States Department of Agriculture (USDA-ARS), Albany, CA, United States
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Jin G, Liu N, Yu B, Jiang Y, Luo H, Huang L, Zhou X, Yan L, Kang Y, Huai D, Ding Y, Chen Y, Wang X, Jiang H, Lei Y, Shen J, Liao B. Identification and Pyramiding Major QTL Loci for Simultaneously Enhancing Aflatoxin Resistance and Yield Components in Peanut. Genes (Basel) 2023; 14:genes14030625. [PMID: 36980897 PMCID: PMC10048167 DOI: 10.3390/genes14030625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 02/10/2023] [Accepted: 02/27/2023] [Indexed: 03/06/2023] Open
Abstract
Peanut is susceptible to Aspergillus flavus infection, and the consequent aflatoxin contamination has been recognized as an important risk factor affecting food safety and industry development. Planting peanut varieties with resistance to aflatoxin contamination is regarded as an ideal approach to decrease the risk in food safety, but most of the available resistant varieties have not been extensively used in production because of their low yield potential mostly due to possessing small pods and seeds. Hence, it is highly necessary to integrate resistance to aflatoxin and large seed weight. In this study, an RIL population derived from a cross between Zhonghua 16 with high yield and J 11 with resistance to infection of A. flavus and aflatoxin production, was used to identify quantitative trait locus (QTL) for aflatoxin production (AP) resistance and hundred-seed weight (HSW). From combined analysis using a high-density genetic linkage map constructed, 11 QTLs for AP resistance with 4.61–11.42% phenotypic variation explanation (PVE) and six QTLs for HSW with 3.20–28.48% PVE were identified, including three major QTLs for AP resistance (qAFTA05.1, qAFTB05.2 and qAFTB06.3) and three for HSW (qHSWA05, qHSWA08 and qHSWB06). In addition, qAFTA05.1, qAFTB06.3, qHSWA05, qHSWA08 and qHSWB06 were detected in multiple environments. The aflatoxin contents under artificial inoculation were decreased by 34.77–47.67% in those segregated lines harboring qAFTA05.1, qAFTB05.2 and qAFTB06.3, while the HSWs were increased by 47.56–49.46 g in other lines harboring qHSWA05, qHSWA08 and qHSWB06. Conditional QTL mapping indicated that HSW and percent seed infection index (PSII) had no significant influence on aflatoxin content. Interestingly, the QT 1059 simultaneously harboring alleles of aflatoxin content including qAFTA05.1 and qAFTB05.2, alleles of PSII including qPSIIB03.1, qPSIIB03.2, and qPSIIB10 and alleles of HSW including qHSWA05, qHSWB06, qHSWA08 had better resistance to A. flavus infection and to toxin production and higher yield potential compared with the two parents of the RIL. The above identified major loci for AP resistance and HWS would be helpful for marker-assisted selection in peanut breeding.
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Affiliation(s)
- Gaorui Jin
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Ministry of Agriculture and Rural Affairs, Wuhan 430062, China
- National Key Laboratory of Crop Genetic Improvement, National Sub-Center of Rapeseed Improvement in Wuhan, Huazhong Agricultural University, Wuhan 430070, China
| | - Nian Liu
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Ministry of Agriculture and Rural Affairs, Wuhan 430062, China
| | - Bolun Yu
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Ministry of Agriculture and Rural Affairs, Wuhan 430062, China
| | - Yifei Jiang
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Ministry of Agriculture and Rural Affairs, Wuhan 430062, China
| | - Huaiyong Luo
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Ministry of Agriculture and Rural Affairs, Wuhan 430062, China
| | - Li Huang
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Ministry of Agriculture and Rural Affairs, Wuhan 430062, China
| | - Xiaojing Zhou
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Ministry of Agriculture and Rural Affairs, Wuhan 430062, China
| | - Liying Yan
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Ministry of Agriculture and Rural Affairs, Wuhan 430062, China
| | - Yanping Kang
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Ministry of Agriculture and Rural Affairs, Wuhan 430062, China
| | - Dongxin Huai
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Ministry of Agriculture and Rural Affairs, Wuhan 430062, China
| | - Yinbing Ding
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Ministry of Agriculture and Rural Affairs, Wuhan 430062, China
| | - Yuning Chen
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Ministry of Agriculture and Rural Affairs, Wuhan 430062, China
| | - Xin Wang
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Ministry of Agriculture and Rural Affairs, Wuhan 430062, China
| | - Huifang Jiang
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Ministry of Agriculture and Rural Affairs, Wuhan 430062, China
| | - Yong Lei
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Ministry of Agriculture and Rural Affairs, Wuhan 430062, China
| | - Jinxiong Shen
- National Key Laboratory of Crop Genetic Improvement, National Sub-Center of Rapeseed Improvement in Wuhan, Huazhong Agricultural University, Wuhan 430070, China
| | - Boshou Liao
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Ministry of Agriculture and Rural Affairs, Wuhan 430062, China
- Correspondence:
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Regulator of G Protein Signaling Contributes to the Development and Aflatoxin Biosynthesis in Aspergillus flavus through the Regulation of Gα Activity. Appl Environ Microbiol 2022; 88:e0024422. [PMID: 35638847 PMCID: PMC9238415 DOI: 10.1128/aem.00244-22] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Heterotrimeric G-proteins play crucial roles in growth, asexual development, and pathogenicity of fungi. The regulator of G-protein signaling (RGS) proteins function as negative regulators of the G proteins to control the activities of GTPase in Gα subunits. In this study, we functionally characterized the six RGS proteins (i.e., RgsA, RgsB, RgsC, RgsD, RgsE, and FlbA) in the pathogenic fungus Aspergillus flavus. All the aforementioned RGS proteins were also found to be functionally different in conidiation, aflatoxin (AF) biosynthesis, and pathogenicity in A. flavus. Apart from FlbA, all other RGS proteins play a negative role in regulating both the synthesis of cyclic AMP (cAMP) and the activation of protein kinase A (PKA). Additionally, we also found that although RgsA and RgsE play a negative role in regulating the FadA-cAMP/PKA pathway, they function distinctly in aflatoxin biosynthesis. Similarly, RgsC is important for aflatoxin biosynthesis by negatively regulating the GanA-cAMP/PKA pathway. PkaA, which is the cAMP-dependent protein kinase catalytic subunit, also showed crucial influences on A. flavus phenotypes. Overall, our results demonstrated that RGS proteins play multiple roles in the development, pathogenicity, and AF biosynthesis in A. flavus through the regulation of Gα subunits and cAMP-PKA signals. IMPORTANCE RGS proteins, as crucial regulators of the G protein signaling pathway, are widely distributed in fungi, while little is known about their roles in Aspergillus flavus development and aflatoxin. In this study, we identified six RGS proteins in A. flavus and revealed that these proteins have important functions in the regulation of conidia, sclerotia, and aflatoxin formation. Our findings provide evidence that the RGS proteins function upstream of cAMP-PKA signaling by interacting with the Gα subunits (GanA and FadA). This study provides valuable information for controlling the contamination of A. flavus and mycotoxins produced by this fungus in pre- and postharvest of agricultural crops.
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Yang K, Tian J, Keller NP. Post-translational modifications drive secondary metabolite biosynthesis in Aspergillus: a review. Environ Microbiol 2022; 24:2857-2881. [PMID: 35645150 PMCID: PMC9545273 DOI: 10.1111/1462-2920.16034] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2022] [Revised: 04/23/2022] [Accepted: 04/26/2022] [Indexed: 12/26/2022]
Abstract
Post‐translational modifications (PTMs) are important for protein function and regulate multiple cellular processes and secondary metabolites (SMs) in fungi. Aspergillus species belong to a genus renown for an abundance of bioactive secondary metabolites, many important as toxins, pharmaceuticals and in industrial production. The genes required for secondary metabolites are typically co‐localized in biosynthetic gene clusters (BGCs), which often localize in heterochromatic regions of genome and are ‘turned off’ under laboratory condition. Efforts have been made to ‘turn on’ these BGCs by genetic manipulation of histone modifications, which could convert the heterochromatic structure to euchromatin. Additionally, non‐histone PTMs also play critical roles in the regulation of secondary metabolism. In this review, we collate the known roles of epigenetic and PTMs on Aspergillus SM production. We also summarize the proteomics approaches and bioinformatics tools for PTM identification and prediction and provide future perspectives on the emerging roles of PTM on regulation of SM biosynthesis in Aspergillus and other fungi.
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Affiliation(s)
- Kunlong Yang
- School of Life Science, Jiangsu Normal University, Xuzhou, 221116, Jiangsu Province, People's Republic of China.,Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, Wisconsin, 53705, USA
| | - Jun Tian
- School of Life Science, Jiangsu Normal University, Xuzhou, 221116, Jiangsu Province, People's Republic of China
| | - Nancy P Keller
- Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, Wisconsin, 53705, USA
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Zhu GY, Wang X, Chen TM, Wang SY, Chen X, Song ZW, Shi XC, Laborda P. First Report of Aspergillus flavus Causing Fruit Rot on Kiwifruit in China. PLANT DISEASE 2022; 106:PDIS08211771PDN. [PMID: 34879727 DOI: 10.1094/pdis-08-21-1771-pdn] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Affiliation(s)
- G-Y Zhu
- School of Life Sciences, Nantong University, Nantong 226019, People's Republic of China
| | - X Wang
- School of Life Sciences, Nantong University, Nantong 226019, People's Republic of China
| | - T-M Chen
- School of Life Sciences, Nantong University, Nantong 226019, People's Republic of China
| | - S-Y Wang
- School of Life Sciences, Nantong University, Nantong 226019, People's Republic of China
| | - X Chen
- School of Life Sciences, Nantong University, Nantong 226019, People's Republic of China
| | - Z-W Song
- Eco-Environmental Protection Research Institute, Shanghai Academy of Agricultural Sciences, Shanghai 201403, People's Republic of China
| | - X-C Shi
- School of Life Sciences, Nantong University, Nantong 226019, People's Republic of China
| | - P Laborda
- School of Life Sciences, Nantong University, Nantong 226019, People's Republic of China
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Tan C, Deng JL, Zhang F, Zhu Z, Yan LJ, Zhang MJ, Yuan J, Wang SH. CWI pathway participated in vegetative growth and pathogenicity through a downstream effector AflRlm1 in Aspergillus flavus. iScience 2021; 24:103159. [PMID: 34693219 PMCID: PMC8517163 DOI: 10.1016/j.isci.2021.103159] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 08/01/2021] [Accepted: 09/17/2021] [Indexed: 11/26/2022] Open
Abstract
The cell wall is an essential dynamic structure for shielding fungus from environmental stress, and its synthesizing and remodeling are regulated by the cell wall integrity (CWI) pathway. Here, we explored the roles of a putative downstream effector AflRlm1 of CWI pathway in Aspergillus flavus. The results showed that AflRlm1 played a positive role in conidia production, sclerotium formation, aflatoxin biosynthesis, and pathogenicity. Furthermore, we provided evidence for the physical connection between AflRlm1 and AflSlt2 and determined the role of AflSlt2 in the phosphorylation of AflRlm1. Then, we discovered the importance of WSCs (cell wall integrity and stress response component) to the CWI signal and the process of AflRlm1 transferring to the nucleus after receiving the signal. Overall, this study clarified the transmission process of CWI signals and proves that the CWI pathway plays a key role in the development of A. flavus and the production of aflatoxin combined with transcriptome data analysis. Linked the CWI pathway from membrane receptors to transcription factors in A. flavus Found the phosphorylate activation and subcellular metastasis of AflRlm1 in stress Discovered the important role of AflRlm1 in aflatoxin biosynthesis
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Affiliation(s)
- Can Tan
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Ji-Li Deng
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Feng Zhang
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Zhuo Zhu
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Li-Juan Yan
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Meng-Juan Zhang
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Jun Yuan
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Shi-Hua Wang
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
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Updates on the Functions and Molecular Mechanisms of the Genes Involved in Aspergillus flavus Development and Biosynthesis of Aflatoxins. J Fungi (Basel) 2021; 7:jof7080666. [PMID: 34436205 PMCID: PMC8401812 DOI: 10.3390/jof7080666] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Revised: 08/08/2021] [Accepted: 08/10/2021] [Indexed: 12/13/2022] Open
Abstract
Aspergillus flavus (A. flavus) is a ubiquitous and opportunistic fungal pathogen that causes invasive and non-invasive aspergillosis in humans and animals. This fungus is also capable of infecting a large number of agriculture crops (e.g., peanuts, maze, cotton seeds, rice, etc.), causing economic losses and posing serious food-safety concerns when these crops are contaminated with aflatoxins, the most potent naturally occurring carcinogens. In particular, A. flavus and aflatoxins are intensely studied, and they continue to receive considerable attention due to their detrimental effects on humans, animals, and crops. Although several studies have been published focusing on the biosynthesis of the aforementioned secondary metabolites, some of the molecular mechanisms (e.g., posttranslational modifications, transcription factors, transcriptome, proteomics, metabolomics and transcriptome, etc.) involved in the fungal development and aflatoxin biosynthesis in A. flavus are still not fully understood. In this study, a review of the recently published studies on the function of the genes and the molecular mechanisms involved in development of A. flavus and the production of its secondary metabolites is presented. It is hoped that the information provided in this review will help readers to develop effective strategies to reduce A. flavus infection and aflatoxin production.
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Ssu72 Regulates Fungal Development, Aflatoxin Biosynthesis and Pathogenicity in Aspergillus flavus. Toxins (Basel) 2020; 12:toxins12110717. [PMID: 33202955 PMCID: PMC7696088 DOI: 10.3390/toxins12110717] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 11/02/2020] [Accepted: 11/03/2020] [Indexed: 12/18/2022] Open
Abstract
The RNA polymerase II (Pol II) transcription process is coordinated by the reversible phosphorylation of its largest subunit-carboxy terminal domain (CTD). Ssu72 is identified as a CTD phosphatase with specificity for phosphorylation of Ser5 and Ser7 and plays critical roles in regulation of transcription cycle in eukaryotes. However, the biofunction of Ssu72 is still unknown in Aspergillus flavus, which is a plant pathogenic fungus and produces one of the most toxic mycotoxins-aflatoxin. Here, we identified a putative phosphatase Ssu72 and investigated the function of Ssu72 in A. flavus. Deletion of ssu72 resulted in severe defects in vegetative growth, conidiation and sclerotia formation. Additionally, we found that phosphatase Ssu72 positively regulates aflatoxin production through regulating expression of aflatoxin biosynthesis cluster genes. Notably, seeds infection assays indicated that phosphatase Ssu72 is crucial for pathogenicity of A. flavus. Furthermore, the Δssu72 mutant exhibited more sensitivity to osmotic and oxidative stresses. Taken together, our study suggests that the putative phosphatase Ssu72 is involved in fungal development, aflatoxin production and pathogenicity in A. flavus, and may provide a novel strategy to prevent the contamination of this pathogenic fungus.
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