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Niu A, Tan L, Tan S, Wang G, Qiu W. The Temporal Dynamics of Sensitivity, Aflatoxin Production, and Oxidative Stress of Aspergillus flavus in Response to Cinnamaldehyde Vapor. Foods 2023; 12:4311. [PMID: 38231749 DOI: 10.3390/foods12234311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 11/16/2023] [Accepted: 11/23/2023] [Indexed: 01/19/2024] Open
Abstract
Cinnamaldehyde (CA), a natural plant extract, possesses notable antimicrobial properties and the ability to inhibit mycotoxin synthesis. This study investigated the effects of different concentrations of gaseous CA on A. flavus and found that higher concentrations exhibited fungicidal effects, while lower concentrations exerted fungistatic effects. Although all A. flavus strains exhibited similar responses to CA vapor, the degree of response varied among them. Notably, A. flavus strains HN-1, JX-3, JX-4, and HN-8 displayed higher sensitivity. Exposure to CA vapor led to slight damage to A. flavus, induced oxidative stress, and inhibited aflatoxin B1 (AFB1) production. Upon removal of the CA vapor, the damaged A. flavus resumed growth, the oxidative stress weakened, and AFB1 production sharply increased in aflatoxin-producing strains. In the whole process, no aflatoxin was detected in aflatoxin-non-producing A. flavus. Moreover, the qRT-PCR results suggest that the recovery of A. flavus and the subsequent surge of AFB1 content following CA removal were regulated by a drug efflux pump and velvet complex proteins. In summary, these findings emphasize the significance of optimizing the targeted concentrations of antifungal EOs and provide valuable insight for their accurate application.
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Affiliation(s)
- Ajuan Niu
- Key Laboratory of Grains and Oils Quality Control and Processing, Collaborative Innovation Center for Modern Grain Circulation and Safety, College of Food Science and Engineering, Nanjing University of Finance and Economics, Nanjing 210023, China
| | - Leilei Tan
- Key Laboratory of Grains and Oils Quality Control and Processing, Collaborative Innovation Center for Modern Grain Circulation and Safety, College of Food Science and Engineering, Nanjing University of Finance and Economics, Nanjing 210023, China
| | - Song Tan
- Key Laboratory of Grains and Oils Quality Control and Processing, Collaborative Innovation Center for Modern Grain Circulation and Safety, College of Food Science and Engineering, Nanjing University of Finance and Economics, Nanjing 210023, China
| | - Guangyu Wang
- Key Laboratory of Grains and Oils Quality Control and Processing, Collaborative Innovation Center for Modern Grain Circulation and Safety, College of Food Science and Engineering, Nanjing University of Finance and Economics, Nanjing 210023, China
| | - Weifen Qiu
- Key Laboratory of Grains and Oils Quality Control and Processing, Collaborative Innovation Center for Modern Grain Circulation and Safety, College of Food Science and Engineering, Nanjing University of Finance and Economics, Nanjing 210023, China
- Joint Laboratory for International Cooperation in Grain Circulation and Security, Nanjing 210023, China
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Li X, Hou H, Li B, Guo S, Jiang L, Xu C, Xie Y, An M, Zhang C, Wu Y. Identification and physiological activity of (methoxymethyl)triphenylphosphonium chloride as a new phytotoxin isolated from Rhizoctonia solani AG-3 TB. FRONTIERS IN PLANT SCIENCE 2023; 14:1264567. [PMID: 38046597 PMCID: PMC10693298 DOI: 10.3389/fpls.2023.1264567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 11/02/2023] [Indexed: 12/05/2023]
Abstract
Rhizoctonia solani as a cosmopolitan fungus is the causative agent of many crop diseases and leads to significant economic losses in crop production. To explore the toxin structure and physiological activity of R. solani AG-3 TB, high-performance liquid chromatography (HPLC), infrared absorption spectrum (IR), and nuclear magnetic resonance spectrum (NMR) were required. Here, the compound (methoxymethyl)triphenylphosphonium chloride (MMC) with the molecular formula C20H20ClOP was purified and identified from R. solani AG-3 TB. The pure compound MMC treated at 20 μg/mL, 50 μg/mL, and 100 μg/mL can cause obvious necrosis on leaves, increase active oxygen species (AOS), decrease chlorophyll content, and damage cellular structure. The results enrich the understanding of toxin compounds for R. solani and provide valuable insights into the toxicology of R. solani AG-3 TB.
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Affiliation(s)
- Xinchun Li
- Liaoning Key Laboratory of Plant Pathology, College of Plant Protection, Shenyang Agricultural University, Shenyang, China
| | - Huihui Hou
- Liaoning Key Laboratory of Plant Pathology, College of Plant Protection, Shenyang Agricultural University, Shenyang, China
- School of Economics and Management, Liaoning University of Technology, Jinzhou, China
| | - Bin Li
- Quality Inspection Department, Sichuan Province Tobacco Company, Chengdu, China
| | - Shiping Guo
- Quality Inspection Department, Sichuan Province Tobacco Company, Chengdu, China
| | - Lianqiang Jiang
- Quality Inspection Department, Liangshan Branch of Sichuan Province Tobacco Company, Xichang, China
| | - Chuantao Xu
- Liaoning Key Laboratory of Plant Pathology, College of Plant Protection, Shenyang Agricultural University, Shenyang, China
- Quality Inspection Department, Luzhou Branch of Sichuan Province Tobacco Company, Luzhou, China
| | - Yunbo Xie
- Quality Inspection Department, Sichuan Province Tobacco Company, Chengdu, China
| | - Mengnan An
- Liaoning Key Laboratory of Plant Pathology, College of Plant Protection, Shenyang Agricultural University, Shenyang, China
| | - Chong Zhang
- Liaoning Key Laboratory of Plant Pathology, College of Plant Protection, Shenyang Agricultural University, Shenyang, China
| | - Yuanhua Wu
- Liaoning Key Laboratory of Plant Pathology, College of Plant Protection, Shenyang Agricultural University, Shenyang, China
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Qiu M, Qiu L, Deng Q, Fang Z, Sun L, Wang Y, Gooneratne R, Zhao J. L-Cysteine hydrochloride inhibits Aspergillus flavus growth and AFB 1 synthesis by disrupting cell structure and antioxidant system balance. JOURNAL OF HAZARDOUS MATERIALS 2023; 459:132218. [PMID: 37552922 DOI: 10.1016/j.jhazmat.2023.132218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 07/26/2023] [Accepted: 08/02/2023] [Indexed: 08/10/2023]
Abstract
Aflatoxin B1 (AFB1) is the most potent known naturally occurring carcinogen and pose an immense threat to food safety and human health. L-Cysteine hydrochloride (L-CH) is a food additive often used as a fruit and vegetable preservative and also to approved bread consistency. In this study, we investigated the effects and mechanisms of L-CH as an antimicrobial on the growth of Aspergillus flavus (A. flavus) and AFB1 biosynthesis. L-CH significantly inhibited A. flavus mycelial growth, affected mycelial morphology and AFB1 synthesis. Furthermore, L-CH induced glutathione (GSH) synthesis which scavenged intracellular reactive oxygen species (ROS). RNA-Seq indicated that L-CH inhibited hyphal branching, and spore and sclerotia formation by controlling cell wall and spore development-related genes. Activation of the GSH metabolic pathway eliminated intracellular ROS, leading to hyphal dwarfing. L-CH treatment downregulated most of the Aflatoxin (AF) cluster genes and aflS, aflR, AFLA_091090 transcription factors. This study provides new insights into the molecular mechanism of L-CH control of A. flavus and AFB1 foundation. We believe that L-CH could be used as a food additive to control AFB1 in foods and also in the environment.
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Affiliation(s)
- Mei Qiu
- College of Food Science and Technology, Guangdong Ocean University, Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, Key Laboratory of Advanced Processing of Aquatic Products of Guangdong Higher Education Institution, Zhanjiang 524088, China
| | - Lihong Qiu
- Department of Clinical Laboratory, Affiliated Hospital of Guangdong Medical University, Zhanjiang 524001, China
| | - Qi Deng
- College of Food Science and Technology, Guangdong Ocean University, Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, Key Laboratory of Advanced Processing of Aquatic Products of Guangdong Higher Education Institution, Zhanjiang 524088, China.
| | - Zhijia Fang
- College of Food Science and Technology, Guangdong Ocean University, Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, Key Laboratory of Advanced Processing of Aquatic Products of Guangdong Higher Education Institution, Zhanjiang 524088, China
| | - Lijun Sun
- College of Food Science and Technology, Guangdong Ocean University, Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, Key Laboratory of Advanced Processing of Aquatic Products of Guangdong Higher Education Institution, Zhanjiang 524088, China
| | - Yaling Wang
- College of Food Science and Technology, Guangdong Ocean University, Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, Key Laboratory of Advanced Processing of Aquatic Products of Guangdong Higher Education Institution, Zhanjiang 524088, China
| | - Ravi Gooneratne
- Department of Wine, Food and Molecular Biosciences, Faculty of Agriculture and Life Sciences, Lincoln University, Lincoln 7647, New Zealand
| | - Jian Zhao
- School of Chemical Engineering, The University of New South Wales, Sydney, NSW 2052, Australia
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Arreguin-Perez CA, Miranda-Miranda E, Folch-Mallol JL, Cossío-Bayúgar R. Identification of Virulence Factors in Entomopathogenic Aspergillus flavus Isolated from Naturally Infected Rhipicephalus microplus. Microorganisms 2023; 11:2107. [PMID: 37630667 PMCID: PMC10457961 DOI: 10.3390/microorganisms11082107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 08/10/2023] [Accepted: 08/15/2023] [Indexed: 08/27/2023] Open
Abstract
Aspergillus flavus has been found to be an effective entomopathogenic fungus for various arthropods, including ticks. In particular, natural fungal infections in cattle ticks show promise for biocontrol of the Rhipicephalus (Boophilus) microplus tick, which is a major ectoparasite affecting cattle worldwide. Our study aimed to elucidate the specific entomopathogenic virulence factors encoded in the genome of an A. flavus strain isolated from naturally infected cattle ticks. We performed morphological and biochemical phenotyping alongside complete genome sequencing, which revealed that the isolated fungus was A. flavus related to the L morphotype, capable of producing a range of gene-coded entomopathogenic virulence factors, including ribotoxin, aflatoxin, kojic acid, chitinases, killer toxin, and satratoxin. To evaluate the efficacy of this A. flavus strain against ticks, we conducted experimental bioassays using healthy engorged female ticks. A morbidity rate of 90% was observed, starting at a concentration of 105 conidia/mL. At a concentration of 107 conidia/mL, we observed a 50% mortality rate and a 21.5% inhibition of oviposition. The highest levels of hatch inhibition (30.8%) and estimated reproduction inhibition (34.64%) were achieved at a concentration of 108 conidia/mL. Furthermore, the tick larval progeny that hatched from the infected tick egg masses showed evident symptoms of Aspergillus infection after incubation.
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Affiliation(s)
- Cesar A. Arreguin-Perez
- Centro Nacional de Investigación Disciplinaria en Salud Animal e Inocuidad, Instituto Nacional de Investigaciones Forestales Agrícolas y Pecuarias INIFAP, Boulevard Cuauhnahuac 8534, Jiutepec 62574, Morelos, Mexico; (C.A.A.-P.); (E.M.-M.)
- Centro de Investigación en Biotecnología, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, Cuernavaca 62209, Morelos, Mexico;
| | - Estefan Miranda-Miranda
- Centro Nacional de Investigación Disciplinaria en Salud Animal e Inocuidad, Instituto Nacional de Investigaciones Forestales Agrícolas y Pecuarias INIFAP, Boulevard Cuauhnahuac 8534, Jiutepec 62574, Morelos, Mexico; (C.A.A.-P.); (E.M.-M.)
| | - Jorge Luis Folch-Mallol
- Centro de Investigación en Biotecnología, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, Cuernavaca 62209, Morelos, Mexico;
| | - Raquel Cossío-Bayúgar
- Centro Nacional de Investigación Disciplinaria en Salud Animal e Inocuidad, Instituto Nacional de Investigaciones Forestales Agrícolas y Pecuarias INIFAP, Boulevard Cuauhnahuac 8534, Jiutepec 62574, Morelos, Mexico; (C.A.A.-P.); (E.M.-M.)
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Kumar P, Gupta A, Mahato DK, Pandhi S, Pandey AK, Kargwal R, Mishra S, Suhag R, Sharma N, Saurabh V, Paul V, Kumar M, Selvakumar R, Gamlath S, Kamle M, Enshasy HAE, Mokhtar JA, Harakeh S. Aflatoxins in Cereals and Cereal-Based Products: Occurrence, Toxicity, Impact on Human Health, and Their Detoxification and Management Strategies. Toxins (Basel) 2022; 14:toxins14100687. [PMID: 36287956 PMCID: PMC9609140 DOI: 10.3390/toxins14100687] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 09/27/2022] [Accepted: 09/28/2022] [Indexed: 11/08/2022] Open
Abstract
Cereals and cereal-based products are primary sources of nutrition across the world. However, contamination of these foods with aflatoxins (AFs), secondary metabolites produced by several fungal species, has raised serious concerns. AF generation in innate substrates is influenced by several parameters, including the substrate type, fungus species, moisture content, minerals, humidity, temperature, and physical injury to the kernels. Consumption of AF-contaminated cereals and cereal-based products can lead to both acute and chronic health issues related to physical and mental maturity, reproduction, and the nervous system. Therefore, the precise detection methods, detoxification, and management strategies of AFs in cereal and cereal-based products are crucial for food safety as well as consumer health. Hence, this review provides a brief overview of the occurrence, chemical characteristics, biosynthetic processes, health hazards, and detection techniques of AFs, along with a focus on detoxification and management strategies that could be implemented for food safety and security.
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Affiliation(s)
- Pradeep Kumar
- Department of Botany, University of Lucknow, Lucknow 226007, India
- Applied Microbiology Laboratory, Department of Forestry, North Eastern Regional Institute of Science and Technology, Nirjuli 791109, India
- Correspondence: (P.K.); (D.K.M.)
| | - Akansha Gupta
- Department of Dairy Science and Food Technology, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi 221005, India
- CASS Food Research Centre, School of Exercise and Nutrition Sciences, Deakin University, Burwood, VIC 3125, Australia
| | - Dipendra Kumar Mahato
- CASS Food Research Centre, School of Exercise and Nutrition Sciences, Deakin University, Burwood, VIC 3125, Australia
- Correspondence: (P.K.); (D.K.M.)
| | - Shikha Pandhi
- Department of Dairy Science and Food Technology, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi 221005, India
| | - Arun Kumar Pandey
- MMICT&BM(HM), Maharishi Markandeshwar (Deemed to be University), Mullana, Ambala 133207, India
| | - Raveena Kargwal
- Department of Processing and Food Engineering, College of Agricultural Engineering and Technology, Chaudhary Charan Singh Haryana Agricultural University, Hisar 125004, India
| | - Sadhna Mishra
- Department of Dairy Science and Food Technology, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi 221005, India
- Faculty of Agricultural Sciences, GLA University, Mathura 281406, India
| | - Rajat Suhag
- Faculty of Science and Technology, Free University of Bozen-Bolzano, Piazza Università 5, 39100 Bolzano, Italy
| | - Nitya Sharma
- Food and Bioprocess Engineering Laboratory, Centre for Rural Development and Technology, Indian Institute of Technology Delhi, New Delhi 110016, India
| | - Vivek Saurabh
- Division of Food Science and Postharvest Technology, ICAR—Indian Agricultural Research Institute, New Delhi 110012, India
| | - Veena Paul
- Department of Dairy Science and Food Technology, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi 221005, India
| | - Manoj Kumar
- Chemical and Biochemical Processing Division, ICAR—Central Institute for Research on Cotton Technology, Mumbai 400019, India
| | - Raman Selvakumar
- Centre for Protected Cultivation Technology, ICAR-Indian Agricultural Research Institute, Pusa Campus, New Delhi 110012, India
| | - Shirani Gamlath
- CASS Food Research Centre, School of Exercise and Nutrition Sciences, Deakin University, Burwood, VIC 3125, Australia
| | - Madhu Kamle
- Applied Microbiology Laboratory, Department of Forestry, North Eastern Regional Institute of Science and Technology, Nirjuli 791109, India
| | - Hesham Ali El Enshasy
- Institute of Bioproduct Development, Universiti Teknologi Malaysia (UTM), Skudai 81310, Malaysia
- City of Scientific Research and Technology Applications, New Burg Al Arab, Alexandria 21934, Egypt
| | - Jawahir A. Mokhtar
- Department of Medical Microbiology and Parasitology, Faculty of Medicine, King Abdulaziz University Hospital, Jeddah 21589, Saudi Arabia
- Vaccines and Immunotherapy Unit, King Fahad Medical Research Center, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Steve Harakeh
- King Fahd Medical Research Center, King Abdulaziz University, Jeddah 21589, Saudi Arabia
- Yousef Abdul Latif Jameel Scientific Chair of Prophetic Medicine Application, Faculty of Medicine (FM), King Abdulaziz University, Jeddah 21589, Saudi Arabia
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Sweany RR, DeRobertis CD, Kaller MD, Damann KE. Intraspecific Growth and Aflatoxin Inhibition Responses to Atoxigenic Aspergillus flavus: Evidence of Secreted, Inhibitory Substances in Biocontrol. PHYTOPATHOLOGY 2022; 112:2084-2098. [PMID: 35502929 DOI: 10.1094/phyto-01-21-0022-r] [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: 06/14/2023]
Abstract
The fungus Aspergillus flavus infects corn, peanut, and cottonseed, and contaminates seeds with acutely poisonous and carcinogenic aflatoxin. Aflatoxin contamination is a perennial threat in tropical and subtropical climates. Nonaflatoxin-producing isolates (atoxigenic) are deployed in fields to mitigate aflatoxin contamination. The biocontrol competitively excludes toxigenic A. flavus via direct replacement and thigmoregulated (touch) toxin inhibition mechanisms. To understand the broad-spectrum toxin inhibition, toxigenic isolates representing different mating types and sclerotia sizes were individually cocultured with different atoxigenic biocontrol isolates. To determine whether more inhibitory isolates had a competitive advantage to displace or touch inhibit toxigenic isolates, biomass accumulation rates were determined for each isolate. Finally, to determine whether atoxigenic isolates could inhibit aflatoxin production without touch, atoxigenic isolates were grown separated from a single toxigenic isolate by a membrane. Atoxigenic isolates 17, Af36, and K49 had superior abilities to inhibit toxin production. Small (<400 µm) sclerotial, Mat1-1 isolates were not as completely inhibited as others by most atoxigenic isolates. As expected for both direct replacement and touch inhibition, the fastest-growing atoxigenic isolates inhibited aflatoxin production the most, except for atoxigenic Af36 and K49. Aflatoxin production was inhibited when toxigenic and atoxigenic isolates were grown separately, especially by slow-growing atoxigenic Af36 and K49. Additionally, fungus-free filtrates from atoxigenic cultures inhibited aflatoxin production. Toxin production inhibition without direct contact revealed secretion of diffusible chemicals as an additional biocontrol mechanism. Biocontrol formulations should be improved by identifying isolates with broad-spectrum, high-inhibition capabilities and production of secreted inhibitory chemicals.
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Affiliation(s)
- Rebecca R Sweany
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803
| | - Catherine D DeRobertis
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803
| | - Michael D Kaller
- School of Renewable Natural Resources, Louisiana State University Agricultural Center, Baton Rouge, LA 70803
| | - Kenneth E Damann
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803
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Sweany RR, Breunig M, Opoku J, Clay K, Spatafora JW, Drott MT, Baldwin TT, Fountain JC. Why Do Plant-Pathogenic Fungi Produce Mycotoxins? Potential Roles for Mycotoxins in the Plant Ecosystem. PHYTOPATHOLOGY 2022; 112:2044-2051. [PMID: 35502928 DOI: 10.1094/phyto-02-22-0053-sym] [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: 06/14/2023]
Abstract
For many plant-pathogenic or endophytic fungi, production of mycotoxins, which are toxic to humans, may present a fitness gain. However, associations between mycotoxin production and plant pathogenicity or virulence is inconsistent and difficult due to the complexity of these host-pathogen interactions and the influences of environmental and insect factors. Aflatoxin receives a lot of attention due to its potent toxicity and carcinogenicity but the connection between aflatoxin production and pathogenicity is complicated by the pathogenic ability and prevalence of nonaflatoxigenic isolates in crops. Other toxins directly aid fungi in planta, trichothecenes are important virulence factors, and ergot alkaloids limit herbivory and fungal consumption due to insect toxicity. We review a panel discussion at the American Phytopathological Society's Plant Health 2021 conference, which gathered diverse experts representing different research sectors, career stages, ethnicities, and genders to discuss the diverse roles of mycotoxins in the lifestyles of filamentous fungi of the families Clavicipitaceae, Trichocomaceae (Eurotiales), and Nectriaceae (Hypocreales).
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Affiliation(s)
- Rebecca R Sweany
- United States Department of Agriculture-Agricultural Research Service (USDA-ARS) Food and Feed Safety Research Unit, Southern Regional Research Center, New Orleans, LA 70124
| | - Mikaela Breunig
- Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI 78824
| | - Joseph Opoku
- USDA-ARS Pest Management and Biological Control Research Unit, U.S. Arid-Land Agricultural Research Center, Tucson, AZ 85701
| | - Keith Clay
- Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, LA 70118
| | - Joseph W Spatafora
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97333
| | - Milton T Drott
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI 53706
| | - Thomas T Baldwin
- Department of Plant Pathology, North Dakota State University, Fargo, ND 58108
| | - Jake C Fountain
- Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, MS State, MS 39762
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de Obeso Fernandez del Valle A, Scheckhuber CQ. Superoxide Dismutases in Eukaryotic Microorganisms: Four Case Studies. Antioxidants (Basel) 2022; 11:antiox11020188. [PMID: 35204070 PMCID: PMC8868140 DOI: 10.3390/antiox11020188] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 01/12/2022] [Accepted: 01/16/2022] [Indexed: 01/08/2023] Open
Abstract
Various components in the cell are responsible for maintaining physiological levels of reactive oxygen species (ROS). Several different enzymes exist that can convert or degrade ROS; among them are the superoxide dismutases (SODs). If left unchecked, ROS can cause damage that leads to pathology, can contribute to aging, and may, ultimately, cause death. SODs are responsible for converting superoxide anions to hydrogen peroxide by dismutation. Here we review the role of different SODs on the development and pathogenicity of various eukaryotic microorganisms relevant to human health. These include the fungal aging model, Podospora anserina; various members of the genus Aspergillus that can potentially cause aspergillosis; the agents of diseases such as Chagas and sleeping disease, Trypanosoma cruzi and Trypanosoma brucei, respectively; and, finally, pathogenic amoebae, such as Acanthamoeba spp. In these organisms, SODs fulfill essential and often regulatory functions that come into play during processes such as the development, host infection, propagation, and control of gene expression. We explore the contribution of SODs and their related factors in these microorganisms, which have an established role in health and disease.
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Pennerman KK, Yin G, Bennett JW. Eight-carbon volatiles: prominent fungal and plant interaction compounds. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:487-497. [PMID: 34727164 DOI: 10.1093/jxb/erab438] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 09/24/2021] [Indexed: 06/13/2023]
Abstract
Signaling via volatile organic compounds (VOCs) has historically been studied mostly by entomologists; however, botanists and mycologists are increasingly aware of the physiological potential of chemical communication in the gas phase. Most research to date focuses on the observed effects of VOCs on different organisms such as differential growth or metabolite production. However, with the increased interest in volatile signaling, more researchers are investigating the molecular mechanisms for these effects. Eight-carbon VOCs are among the most prevalent and best-studied fungal volatiles. Therefore, this review emphasizes examples of eight-carbon VOCs affecting plants and fungi. These compounds display different effects that include growth suppression in both plants and fungi, induction of defensive behaviors such as accumulation of mycotoxins, phytohormone signaling cascades, and the inhibition of spore and seed germination. Application of '-omics' and other next-generation sequencing techniques is poised to decipher the mechanistic basis of volatiles in plant-fungal communication.
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Affiliation(s)
- Kayla K Pennerman
- Joint Institute for Food Safety and Applied Nutrition, University of Maryland, College Park, MD 20742, USA
- United States Department of Agriculture, Toxicology and Mycotoxin Research Unit, Athens, GA 30605, USA
| | - Guohua Yin
- United States Department of Agriculture, Mycotoxin Prevention and Applied Microbiology Research Unit, National Center for Agricultural Utilization Research, Peoria, IL 61604, USA
- Department of Plant Biology, Rutgers University, The State University of New Jersey, New Brunswick, NJ 08901, USA
| | - Joan W Bennett
- Department of Plant Biology, Rutgers University, The State University of New Jersey, New Brunswick, NJ 08901, USA
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Sweany RR, Mack BM, Moore GG, Gilbert MK, Cary JW, Lebar MD, Rajasekaran K, Damann Jr. KE. Genetic Responses and Aflatoxin Inhibition during Co-Culture of Aflatoxigenic and Non-Aflatoxigenic Aspergillus flavus. Toxins (Basel) 2021; 13:794. [PMID: 34822579 PMCID: PMC8618995 DOI: 10.3390/toxins13110794] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 10/30/2021] [Accepted: 11/05/2021] [Indexed: 11/16/2022] Open
Abstract
Aflatoxin is a carcinogenic mycotoxin produced by Aspergillus flavus. Non-aflatoxigenic (Non-tox) A. flavus isolates are deployed in corn fields as biocontrol because they substantially reduce aflatoxin contamination via direct replacement and additionally via direct contact or touch with toxigenic (Tox) isolates and secretion of inhibitory/degradative chemicals. To understand touch inhibition, HPLC analysis and RNA sequencing examined aflatoxin production and gene expression of Non-tox isolate 17 and Tox isolate 53 mono-cultures and during their interaction in co-culture. Aflatoxin production was reduced by 99.7% in 72 h co-cultures. Fewer than expected unique reads were assigned to Tox 53 during co-culture, indicating its growth and/or gene expression was inhibited in response to Non-tox 17. Predicted secreted proteins and genes involved in oxidation/reduction were enriched in Non-tox 17 and co-cultures compared to Tox 53. Five secondary metabolite (SM) gene clusters and kojic acid synthesis genes were upregulated in Non-tox 17 compared to Tox 53 and a few were further upregulated in co-cultures in response to touch. These results suggest Non-tox strains can inhibit growth and aflatoxin gene cluster expression in Tox strains through touch. Additionally, upregulation of other SM genes and redox genes during the biocontrol interaction demonstrates a potential role of inhibitory SMs and antioxidants as additional biocontrol mechanisms and deserves further exploration to improve biocontrol formulations.
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Affiliation(s)
- Rebecca R. Sweany
- Food and Feed Safety Research Unit, Southern Regional Research Center, US Department of Agriculture, New Orleans, LA 70124, USA; (B.M.M.); (M.K.G.); (J.W.C.); (M.D.L.)
- Department of Plant Pathology and Crop Physiology, Louisiana State University, Baton Rouge, LA 70808, USA;
| | - Brian M. Mack
- Food and Feed Safety Research Unit, Southern Regional Research Center, US Department of Agriculture, New Orleans, LA 70124, USA; (B.M.M.); (M.K.G.); (J.W.C.); (M.D.L.)
- Department of Plant Pathology and Crop Physiology, Louisiana State University, Baton Rouge, LA 70808, USA;
| | - Geromy G. Moore
- Food and Feed Safety Research Unit, Southern Regional Research Center, US Department of Agriculture, New Orleans, LA 70124, USA; (B.M.M.); (M.K.G.); (J.W.C.); (M.D.L.)
- Department of Plant Pathology and Crop Physiology, Louisiana State University, Baton Rouge, LA 70808, USA;
| | - Matthew K. Gilbert
- Food and Feed Safety Research Unit, Southern Regional Research Center, US Department of Agriculture, New Orleans, LA 70124, USA; (B.M.M.); (M.K.G.); (J.W.C.); (M.D.L.)
- Department of Plant Pathology and Crop Physiology, Louisiana State University, Baton Rouge, LA 70808, USA;
| | - Jeffrey W. Cary
- Food and Feed Safety Research Unit, Southern Regional Research Center, US Department of Agriculture, New Orleans, LA 70124, USA; (B.M.M.); (M.K.G.); (J.W.C.); (M.D.L.)
- Department of Plant Pathology and Crop Physiology, Louisiana State University, Baton Rouge, LA 70808, USA;
| | - Matthew D. Lebar
- Food and Feed Safety Research Unit, Southern Regional Research Center, US Department of Agriculture, New Orleans, LA 70124, USA; (B.M.M.); (M.K.G.); (J.W.C.); (M.D.L.)
- Department of Plant Pathology and Crop Physiology, Louisiana State University, Baton Rouge, LA 70808, USA;
| | - Kanniah Rajasekaran
- Food and Feed Safety Research Unit, Southern Regional Research Center, US Department of Agriculture, New Orleans, LA 70124, USA; (B.M.M.); (M.K.G.); (J.W.C.); (M.D.L.)
- Department of Plant Pathology and Crop Physiology, Louisiana State University, Baton Rouge, LA 70808, USA;
| | - Kenneth E. Damann Jr.
- Department of Plant Pathology and Crop Physiology, Louisiana State University, Baton Rouge, LA 70808, USA;
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11
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Singh Y, Nair AM, Verma PK. Surviving the odds: From perception to survival of fungal phytopathogens under host-generated oxidative burst. PLANT COMMUNICATIONS 2021; 2:100142. [PMID: 34027389 PMCID: PMC8132124 DOI: 10.1016/j.xplc.2021.100142] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 12/04/2020] [Accepted: 01/01/2021] [Indexed: 05/04/2023]
Abstract
Fungal phytopathogens pose a serious threat to global crop production. Only a handful of strategies are available to combat these fungal infections, and the increasing incidence of fungicide resistance is making the situation worse. Hence, the molecular understanding of plant-fungus interactions remains a primary focus of plant pathology. One of the hallmarks of host-pathogen interactions is the overproduction of reactive oxygen species (ROS) as a plant defense mechanism, collectively termed the oxidative burst. In general, high accumulation of ROS restricts the growth of pathogenic organisms by causing localized cell death around the site of infection. To survive the oxidative burst and achieve successful host colonization, fungal phytopathogens employ intricate mechanisms for ROS perception, ROS neutralization, and protection from ROS-mediated damage. Together, these countermeasures maintain the physiological redox homeostasis that is essential for cell viability. In addition to intracellular antioxidant systems, phytopathogenic fungi also deploy interesting effector-mediated mechanisms for extracellular ROS modulation. This aspect of plant-pathogen interactions is significantly under-studied and provides enormous scope for future research. These adaptive responses, broadly categorized into "escape" and "exploitation" mechanisms, are poorly understood. In this review, we discuss the oxidative stress response of filamentous fungi, their perception signaling, and recent insights that provide a comprehensive understanding of the distinct survival mechanisms of fungal pathogens in response to the host-generated oxidative burst.
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Affiliation(s)
- Yeshveer Singh
- Plant Immunity Laboratory, National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi 110067, India
| | - Athira Mohandas Nair
- Plant Immunity Laboratory, National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi 110067, India
| | - Praveen Kumar Verma
- Plant Immunity Laboratory, National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi 110067, India
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
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12
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Fountain J, Pandey A, Nayak S, Bajaj P, Wang H, Kumar V, Chitikineni A, Abbas H, Scully B, Kemerait R, Pandey M, Guo B, Varshney R. Transcriptional responses of toxigenic and atoxigenic isolates of Aspergillus flavus to oxidative stress in aflatoxin-conducive and non-conducive media. WORLD MYCOTOXIN J 2020. [DOI: 10.3920/wmj2020.2566] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Aflatoxin production by isolates of Aspergillus flavus varies, ranging from highly toxigenic to completely atoxigenic. Several mechanisms have been identified which regulate aflatoxin production including medium carbon source and oxidative stress. In recent studies, aflatoxin production has been implicated in partially ameliorating oxidative stress in A. flavus. To better understand the role of aflatoxin production in oxidative stress responses, a selection of toxigenic and atoxigenic isolates of A. flavus with moderate to high oxidative stress tolerance were exposed to increasing concentrations of H2O2 in both aflatoxin-conducive and non-conducive media. Mycelial mats were collected for global transcriptome sequencing followed by differential expression, functional prediction, and weighted co-expression analyses. Oxidative stress and medium carbon source had a significant effect on the expression of several secondary metabolite gene clusters including those for aflatoxin, aflatrem, aflavarin, cyclopiazonic acid, and kojic acid. Atoxigenic biological control isolates showed less differential expression under stress than other atoxigenic isolates suggesting expression profiles may be useful in screening. Increasing stress also resulted in regulation of SakA/Hog1 and MpkA MAP kinase signalling pathways pointing to their potential roles in regulating oxidative stress responses. Their expression was also influenced by medium carbon source. These results suggest that aflatoxin production along with that of other mycotoxins may occur as part of a concerted coping mechanism for oxidative stress and its effects in the environment. This mechanism is also regulated by availability of simple sugars and glycolytic compounds for their biosynthesis.
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Affiliation(s)
- J.C. Fountain
- USDA-ARS, Crop Protection and Management Research Unit, Tifton, GA 31793, USA
- Department of Plant Pathology, University of Georgia, Tifton, GA 31793, USA
- Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, Starkville, MS 39762, USA
| | - A.K. Pandey
- Center of Excellence in Genomics & Systems Biology, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana 502324, India
| | - S.N. Nayak
- Department of Biotechnology, University of Agricultural Sciences, Dharwad, Karnataka 580005, India
| | - P. Bajaj
- Center of Excellence in Genomics & Systems Biology, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana 502324, India
| | - H. Wang
- Department of Plant Pathology, University of Georgia, Tifton, GA 31793, USA
| | - V. Kumar
- Center of Excellence in Genomics & Systems Biology, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana 502324, India
| | - A. Chitikineni
- Center of Excellence in Genomics & Systems Biology, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana 502324, India
| | - H.K. Abbas
- USDA-ARS, Biological Control of Pests Research Unit, Stoneville, MS, USA
| | - B.T. Scully
- USDA-ARS, National Horticultural Research Laboratory, Fort Pierce, FL, USA
| | - R.C. Kemerait
- Department of Plant Pathology, University of Georgia, Tifton, GA 31793, USA
| | - M.K. Pandey
- Center of Excellence in Genomics & Systems Biology, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana 502324, India
| | - B. Guo
- USDA-ARS, Crop Protection and Management Research Unit, Tifton, GA 31793, USA
| | - R.K. Varshney
- Center of Excellence in Genomics & Systems Biology, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana 502324, India
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13
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Fountain J, Pandey A, Nayak S, Bajaj P, Wang H, Kumar V, Chitikineni A, Abbas H, Scully B, Kemerait R, Pandey M, Guo B, Varshney R. Transcriptional responses of toxigenic and atoxigenic isolates of Aspergillus flavus to oxidative stress in aflatoxin-conducive and non-conducive media. WORLD MYCOTOXIN J 2020. [DOI: 10.3920/wmj2020.test2566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Aflatoxin production by isolates of Aspergillus flavus varies, ranging from highly toxigenic to completely atoxigenic. Several mechanisms have been identified which regulate aflatoxin production including medium carbon source and oxidative stress. In recent studies, aflatoxin production has been implicated in partially ameliorating oxidative stress in A. flavus. To better understand the role of aflatoxin production in oxidative stress responses, a selection of toxigenic and atoxigenic isolates of A. flavus with moderate to high oxidative stress tolerance were exposed to increasing concentrations of H2O2 in both aflatoxin-conducive and non-conducive media. Mycelial mats were collected for global transcriptome sequencing followed by differential expression, functional prediction, and weighted co-expression analyses. Oxidative stress and medium carbon source had a significant effect on the expression of several secondary metabolite gene clusters including those for aflatoxin, aflatrem, aflavarin, cyclopiazonic acid, and kojic acid. Atoxigenic biological control isolates showed less differential expression under stress than other atoxigenic isolates suggesting expression profiles may be useful in screening. Increasing stress also resulted in regulation of SakA/Hog1 and MpkA MAP kinase signalling pathways pointing to their potential roles in regulating oxidative stress responses. Their expression was also influenced by medium carbon source. These results suggest that aflatoxin production along with that of other mycotoxins may occur as part of a concerted coping mechanism for oxidative stress and its effects in the environment. This mechanism is also regulated by availability of simple sugars and glycolytic compounds for their biosynthesis.
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Affiliation(s)
- J.C. Fountain
- USDA-ARS, Crop Protection and Management Research Unit, Tifton, GA 31793, USA
- Department of Plant Pathology, University of Georgia, Tifton, GA 31793, USA
- Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, Starkville, MS 39762, USA
| | - A.K. Pandey
- Center of Excellence in Genomics & Systems Biology, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana 502324, India
| | - S.N. Nayak
- Department of Biotechnology, University of Agricultural Sciences, Dharwad, Karnataka 580005, India
| | - P. Bajaj
- Center of Excellence in Genomics & Systems Biology, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana 502324, India
| | - H. Wang
- Department of Plant Pathology, University of Georgia, Tifton, GA 31793, USA
| | - V. Kumar
- Center of Excellence in Genomics & Systems Biology, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana 502324, India
| | - A. Chitikineni
- Center of Excellence in Genomics & Systems Biology, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana 502324, India
| | - H.K. Abbas
- USDA-ARS, Biological Control of Pests Research Unit, Stoneville, MS, USA
| | - B.T. Scully
- USDA-ARS, National Horticultural Research Laboratory, Fort Pierce, FL, USA
| | - R.C. Kemerait
- Department of Plant Pathology, University of Georgia, Tifton, GA 31793, USA
| | - M.K. Pandey
- Center of Excellence in Genomics & Systems Biology, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana 502324, India
| | - B. Guo
- USDA-ARS, Crop Protection and Management Research Unit, Tifton, GA 31793, USA
| | - R.K. Varshney
- Center of Excellence in Genomics & Systems Biology, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana 502324, India
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Two New Aspergillus flavus Reference Genomes Reveal a Large Insertion Potentially Contributing to Isolate Stress Tolerance and Aflatoxin Production. G3-GENES GENOMES GENETICS 2020; 10:3515-3531. [PMID: 32817124 PMCID: PMC7534430 DOI: 10.1534/g3.120.401405] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Efforts in genome sequencing in the Aspergillus genus have led to the development of quality reference genomes for several important species including A. nidulans, A. fumigatus, and A. oryzae However, less progress has been made for A. flavus As part of the effort of the USDA-ARS Annual Aflatoxin Workshop Fungal Genome Project, the isolate NRRL3357 was sequenced and resulted in a scaffold-level genome released in 2005. Our goal has been biologically driven, focusing on two areas: isolate variation in aflatoxin production and drought stress exacerbating aflatoxin production by A. flavus Therefore, we developed two reference pseudomolecule genome assemblies derived from chromosome arms for two isolates: AF13, a MAT1-2, highly stress tolerant, and highly aflatoxigenic isolate; and NRRL3357, a MAT1-1, less stress tolerant, and moderate aflatoxin producer in comparison to AF13. Here, we report these two reference-grade assemblies for these isolates through a combination of PacBio long-read sequencing and optical mapping, and coupled them with comparative, functional, and phylogenetic analyses. This analysis resulted in the identification of 153 and 45 unique genes in AF13 and NRRL3357, respectively. We also confirmed the presence of a unique 310 Kb insertion in AF13 containing 60 genes. Analysis of this insertion revealed the presence of a bZIP transcription factor, named atfC, which may contribute to isolate pathogenicity and stress tolerance. Phylogenomic analyses comparing these and other available assemblies also suggest that the species complex of A. flavus is polyphyletic.
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15
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Draft Genome Sequences of One Aspergillus parasiticus Isolate and Nine Aspergillus flavus Isolates with Varying Stress Tolerance and Aflatoxin Production. Microbiol Resour Announc 2020; 9:9/37/e00478-20. [PMID: 32912903 PMCID: PMC7484062 DOI: 10.1128/mra.00478-20] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Aspergillus flavus and Aspergillus parasiticus produce carcinogenic aflatoxins during crop infection, with extensive variations in production among isolates, ranging from atoxigenic to highly toxigenic. Here, we report draft genome sequences of one A. parasiticus isolate and nine A. flavus isolates from field environments for use in comparative, functional, and phylogenetic studies.
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16
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Zhu Z, Yang M, Bai Y, Ge F, Wang S. Antioxidant-related catalase CTA1 regulates development, aflatoxin biosynthesis, and virulence in pathogenic fungus Aspergillus flavus. Environ Microbiol 2020; 22:2792-2810. [PMID: 32250030 DOI: 10.1111/1462-2920.15011] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 03/17/2020] [Accepted: 03/31/2020] [Indexed: 11/29/2022]
Abstract
Reactive oxygen species (ROS) induce the synthesis of a myriad of secondary metabolites, including aflatoxins. It raises significant concern as it is a potent environmental contaminant. In Aspergillus flavus., antioxidant enzymes link ROS stress response with coordinated gene regulation of aflatoxin biosynthesis. In this study, we characterized the function of a core component of the antioxidant enzyme catalase (CTA1) of A. flavus. Firstly, we verified the presence of cta1 corresponding protein (CTA1) by Western blot analysis and mass-spectrometry based analysis. Then, the functional study revealed that the growth, sporulation and sclerotia formation significantly increased, while aflatoxins production and virulence were decreased in the cta1 deletion mutant as compared with the WT and complementary strains. Furthermore, the absence of the cta1 gene resulted in a significant rise in the intracellular ROS level, which in turn added to the oxidative stress level of cells. A further quantitative proteomics investigation hinted that in vivo, CTA1 might maintain the ROS level to facilitate the aflatoxin synthesis. All in all, the pleiotropic phenotype of A. flavus CTA1 deletion mutant revealed that the antioxidant system plays a crucial role in fungal development, aflatoxins biosynthesis and virulence.
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Affiliation(s)
- Zhuo Zhu
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Mingkun Yang
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.,State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
| | - Youhuang Bai
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Feng Ge
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
| | - Shihua Wang
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
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17
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Sweany RR, Damann KE. Influence of Neighboring Clonal-Colonies on Aflatoxin Production by Aspergillus flavus. Front Microbiol 2020; 10:3038. [PMID: 32010096 PMCID: PMC6974465 DOI: 10.3389/fmicb.2019.03038] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Accepted: 12/17/2019] [Indexed: 11/13/2022] Open
Abstract
Aspergillus flavus is an ascomycete fungus that infects and contaminates corn, peanuts, cottonseed, and treenuts with acutely toxic and carcinogenic aflatoxins. The ecological function of aflatoxin production is not well understood; though not phytotoxic, aflatoxin may be involved in resisting oxidative stress responses from infection or drought stress in plants. Observation of aflatoxin stimulation in 48-well plates in response to increasing inoculated wells sparked an investigation to determine if A. flavus volatiles influence aflatoxin production in neighboring colonies. Experiments controlling several culture conditions demonstrated a stimulation of aflatoxin production with increased well occupancy independent of pH buffer, moisture, or isolate. However, even with all wells inoculated, aflatoxin production was less in interior wells. Only one isolate stimulated aflatoxin production in a large Petri-dish format containing eight small Petri dishes with shared headspace. Other isolates consistently inhibited aflatoxin production when all eight Petri dishes were inoculated with A. flavus. No contact between cultures and only shared headspace implied the fungus produced inhibitory and stimulatory gases. Adding activated charcoal between wells and dishes prevented inhibition but not stimulation indicating stimulatory and inhibitory gases are different and/or gas is inhibitory at high concentration and stimulatory at lower concentrations. Characterizing stimulatory and inhibitory effects of gases in A. flavus headspace as well as the apparently opposing results in the two systems deserves further investigation. Determining how gases contribute to quorum sensing and communication could facilitate managing or using the gases in modified atmospheres during grain storage to minimize aflatoxin contamination.
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Affiliation(s)
- Rebecca R. Sweany
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, LA, United States
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18
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Fountain JC, Yang L, Pandey MK, Bajaj P, Alexander D, Chen S, Kemerait RC, Varshney RK, Guo B. Carbohydrate, glutathione, and polyamine metabolism are central to Aspergillus flavus oxidative stress responses over time. BMC Microbiol 2019; 19:209. [PMID: 31488075 PMCID: PMC6727485 DOI: 10.1186/s12866-019-1580-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 08/25/2019] [Indexed: 01/08/2023] Open
Abstract
Background The primary and secondary metabolites of fungi are critical for adaptation to environmental stresses, host pathogenicity, competition with other microbes, and reproductive fitness. Drought-derived reactive oxygen species (ROS) have been shown to stimulate aflatoxin production and regulate in Aspergillus flavus, and may function in signaling with host plants. Here, we have performed global, untargeted metabolomics to better understand the role of aflatoxin production in oxidative stress responses, and also explore isolate-specific oxidative stress responses over time. Results Two field isolates of A. flavus, AF13 and NRRL3357, possessing high and moderate aflatoxin production, respectively, were cultured in medium with and without supplementation with 15 mM H2O2, and mycelia were collected following 4 and 7 days in culture for global metabolomics. Overall, 389 compounds were described in the analysis which encompassed 9 biological super-pathways and 47 sub-pathways. These metabolites were examined for differential accumulation. Significant differences were observed in both isolates in response to oxidative stress and when comparing sampling time points. Conclusions The moderately high aflatoxin-producing isolate, NRRL3357, showed extensive stimulation of antioxidant mechanisms and pathways including polyamines metabolism, glutathione metabolism, TCA cycle, and lipid metabolism while the highly aflatoxigenic isolate, AF13, showed a less vigorous response to stress. Carbohydrate pathway levels also imply that carbohydrate repression and starvation may influence metabolite accumulation at the later timepoint. Higher conidial oxidative stress tolerance and antioxidant capacity in AF13 compared to NRRL3357, inferred from their metabolomic profiles and growth curves over time, may be connected to aflatoxin production capability and aflatoxin-related antioxidant accumulation. The coincidence of several of the detected metabolites in H2O2-stressed A. flavus and drought-stressed hosts also suggests their potential role in the interaction between these organisms and their use as markers/targets to enhance host resistance through biomarker selection or genetic engineering. Electronic supplementary material The online version of this article (10.1186/s12866-019-1580-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jake C Fountain
- USDA-ARS, Crop Protection and Management Research Unit, Tifton, GA, 31793, USA.,Department of Plant Pathology, University of Georgia, Tifton, GA, 31793, USA
| | - Liming Yang
- Department of Plant Pathology, University of Georgia, Tifton, GA, 31793, USA.,College of Biology and Environmental Science, Nanjing Forestry University, Nanjing, 210037, China
| | - Manish K Pandey
- International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana, 502324, India
| | - Prasad Bajaj
- International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana, 502324, India
| | | | - Sixue Chen
- Department of Biology, Genetics Institute, and Plant Molecular & Cellular Biology Program, University of Florida, Gainesville, FL, 32611, USA
| | - Robert C Kemerait
- Department of Plant Pathology, University of Georgia, Tifton, GA, 31793, USA
| | - Rajeev K Varshney
- International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana, 502324, India
| | - Baozhu Guo
- USDA-ARS, Crop Protection and Management Research Unit, Tifton, GA, 31793, USA.
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19
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Aspergillus flavus NRRL 35739, a Poor Biocontrol Agent, May Have Increased Relative Expression of Stress Response Genes. J Fungi (Basel) 2019; 5:jof5020053. [PMID: 31226781 PMCID: PMC6616650 DOI: 10.3390/jof5020053] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2019] [Revised: 06/16/2019] [Accepted: 06/18/2019] [Indexed: 12/21/2022] Open
Abstract
Biocontrol of the mycotoxin aflatoxin utilizes non-aflatoxigenic strains of Aspergillus flavus, which have variable success rates as biocontrol agents. One non-aflatoxigenic strain, NRRL 35739, is a notably poor biocontrol agent. Its growth in artificial cultures and on peanut kernels was found to be slower than that of two aflatoxigenic strains, and NRRL 35739 exhibited less sporulation when grown on peanuts. The non-aflatoxigenic strain did not greatly prevent aflatoxin accumulation. Comparison of the transcriptomes of aflatoxigenic and non-aflatoxigenic A. flavus strains AF36, AF70, NRRL 3357, NRRL 35739, and WRRL 1519 indicated that strain NRRL 35739 had increased relative expression of six heat shock and stress response proteins, with the genes having relative read counts in NRRL 35739 that were 25 to 410 times more than in the other four strains. These preliminary findings tracked with current thought that aflatoxin biocontrol efficacy is related to the ability of a non-aflatoxigenic strain to out-compete aflatoxigenic ones. The slower growth of NRRL 35739 might be due to lower stress tolerance or overexpression of stress response(s). Further study of NRRL 35739 is needed to refine our understanding of the genetic basis of competitiveness among A. flavus strains.
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20
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Pennerman KK, Scarsella JB, Yin GH, Hua SST, Hartman TG, Bennett JW. Volatile 1-octen-3-ol increases patulin production by Penicillium expansum on a patulin-suppressing medium. Mycotoxin Res 2019; 35:329-340. [PMID: 31025195 DOI: 10.1007/s12550-019-00348-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 02/26/2019] [Accepted: 02/27/2019] [Indexed: 12/21/2022]
Abstract
1-Octen-3-ol is one of the most abundant volatile compounds associated with fungi and functions as a germination and growth inhibitor in several species. By investigating its effect on the biosynthesis of patulin, a mycotoxin made by Penicillium expansum, it was found that a sub-inhibitory level of volatile 1-octen-3-ol increased accumulation of patulin on a medium that normally suppresses the mycotoxin. Transcriptomic sequencing and comparisons of control and treated P. expansum grown on potato dextrose agar (PDA; patulin permissive) or secondary medium agar (SMA; patulin suppressive) revealed that the expression of gox2, a gene encoding a glucose oxidase, was significantly affected, decreasing 10-fold on PDA and increasing 85-fold on SMA. Thirty other genes, mostly involved in transmembrane transport, oxidation-reduction, and carbohydrate metabolism were also differently expressed on the two media. Transcription factors previously found to be involved in regulation of patulin biosynthesis were not significantly affected despite 1-octen-3-ol increasing patulin production on SMA. Further study is needed to determine the relationship between the upregulation of patulin biosynthesis genes and gox2 on SMA, and to identify the molecular mechanism by which 1-octen-3-ol induced this effect.
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Affiliation(s)
- Kayla K Pennerman
- Department of Plant Biology, Rutgers University, The State University of New Jersey, New Brunswick, NJ, 08901, USA.
| | - Joseph B Scarsella
- Department of Food Science, Rutgers University, The State University of New Jersey, New Brunswick, NJ, 08901, USA
| | - Guo-Hua Yin
- Department of Plant Biology, Rutgers University, The State University of New Jersey, New Brunswick, NJ, 08901, USA
| | - Sui-Sheng T Hua
- Foodborne Toxin Detection and Prevention Research, United States Department of Agriculture, Agricultural Research Service, Albany, CA, 94710, USA
| | - Thomas G Hartman
- Department of Food Science, Rutgers University, The State University of New Jersey, New Brunswick, NJ, 08901, USA
| | - Joan W Bennett
- Department of Plant Biology, Rutgers University, The State University of New Jersey, New Brunswick, NJ, 08901, USA
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21
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Contreras G, Wang N, Schäfer H, Wink M. Oxidative stress and the presence of bacteria increase gene expression of the antimicrobial peptide aclasin, a fungal CSαβ defensin in Aspergillus clavatus. PeerJ 2019; 7:e6290. [PMID: 30828484 PMCID: PMC6394349 DOI: 10.7717/peerj.6290] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 12/15/2018] [Indexed: 12/17/2022] Open
Abstract
Background Antimicrobial peptides (AMPs) represent a broad class of naturally occurring antimicrobial compounds. Plants, invertebrates and fungi produce various AMPs as, for example, defensins. Most of these defensins are characterised by the presence of a cysteine-stabilised α-helical and β-sheet (CSαβ) motif. The changes in gene expression of a fungal CSαβ defensin by stress conditions were investigated in Aspergillus clavatus. A. clavatus produces the CSαβ defensin Aclasin, which is encoded by the aclasin gene. Methods Aclasin expression was evaluated in submerged mycelium cultures under heat shock, osmotic stress, oxidative stress and the presence of bacteria by quantitative real-time PCR. Results Aclasin expression increased two fold under oxidative stress conditions and in the presence of viable and heat-killed Bacillus megaterium. Under heat shock and osmotic stress, aclasin expression decreased. Discussion The results suggest that oxidative stress and the presence of bacteria might regulate fungal defensin expression. Moreover, fungi might recognise microorganisms as plants and animals do.
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Affiliation(s)
- Gabriela Contreras
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Baden-Württemberg, Germany
| | - Nessa Wang
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Baden-Württemberg, Germany
| | - Holger Schäfer
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Baden-Württemberg, Germany
| | - Michael Wink
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Baden-Württemberg, Germany
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22
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Inhibition of Aflatoxin Production by Paraquat and External Superoxide Dismutase in Aspergillus flavus. Toxins (Basel) 2019; 11:toxins11020107. [PMID: 30759855 PMCID: PMC6409742 DOI: 10.3390/toxins11020107] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 02/11/2019] [Accepted: 02/12/2019] [Indexed: 01/01/2023] Open
Abstract
Aflatoxin contamination of crops is a worldwide problem, and elucidation of the regulatory mechanism of aflatoxin production, for example relative to the oxidative–antioxidative system, is needed. Studies have shown that oxidative stress induced by reactive oxygen species promotes aflatoxin production. However, superoxide has been suggested to have the opposite effect. Here, we investigated the effects of the superoxide generator, paraquat, and externally added superoxide dismutase (SOD) on aflatoxin production in Aspergillus flavus. Paraquat with an IC50 value of 54.9 µM inhibited aflatoxin production without affecting fungal growth. It increased cytosolic and mitochondrial superoxide levels and downregulated the transcription of aflatoxin biosynthetic cluster genes, including aflR, a key regulatory protein. The addition of bovine Cu/ZnSOD to the culture medium suppressed the paraquat-induced increase in superoxide levels, but it did not fully restore paraquat-inhibited aflatoxin production because bovine Cu/ZnSOD with an IC50 value of 17.9 µg/mL itself inhibited aflatoxin production. Externally added bovine Cu/ZnSOD increased the SOD activity in fungal cell extracts and upregulated the transcription of genes encoding Cu/ZnSOD and alcohol dehydrogenase. These results suggest that intracellular accumulation of superoxide impairs aflatoxin production by downregulating aflR expression, and that externally added Cu/ZnSOD also suppresses aflatoxin production by a mechanism other than canonical superoxide elimination activity.
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23
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Yao G, Yue Y, Fu Y, Fang Z, Xu Z, Ma G, Wang S. Exploration of the Regulatory Mechanism of Secondary Metabolism by Comparative Transcriptomics in Aspergillus flavus. Front Microbiol 2018; 9:1568. [PMID: 30131770 PMCID: PMC6090018 DOI: 10.3389/fmicb.2018.01568] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 06/25/2018] [Indexed: 12/31/2022] Open
Abstract
Mycotoxins cause a huge threaten to agriculture, food safety, and human and animal life. Among them, aflatoxins (AFs) have always been considered the most potent carcinogens, and filamentous fungi from Aspergillus genus are their major producers, especially A. flavus. Although the biosynthesis path of these chemicals had been well-identified, the regulatory mechanisms controlling expression of AF gene cluster were poorly understood. In this report, genome-wide transcriptome profiles of A. flavus from AF conducing [yeast sucrose media (YES)] and non-conducing [yeast peptone media (YEP)] conditions were compared by using deep RNA sequencing (RNA-seq), and the results revealed that AF biosynthesis pathway and biosynthesis of amino acids were significantly upregulated in YES vs. YEP. Further, a novel LaeA-like methyltransferase AFLA_121330 (Lael1) was identified for the first time, to play a specific role in the regulation of AF biosynthesis. Contrary to LaeA, which gene deletion reduced the level, lael1 deletion resulted in a significant increase in AF production. Further, co-expression network analysis revealed that mitochondrial pyruvate transport and signal peptide processing were potentially involved in AF synthesis for the first time, as well as biological processes of ribosome, branched-chain amino acid biosynthetic process and translation were co-regulated by AfRafA and AfStuA. To sum up, our analyses could provide novel insights into the molecular mechanism for controlling the AF and other secondary metabolite synthesis, adding novel targets for plant breeding and making fungicides.
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Affiliation(s)
- Guangshan Yao
- Fujian Key Laboratory of Pathogenic Fungi and Mycotoxins, Key Laboratory of Biopesticide and Chemical Biology of Ministry of Education, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Yuewei Yue
- Fujian Key Laboratory of Pathogenic Fungi and Mycotoxins, Key Laboratory of Biopesticide and Chemical Biology of Ministry of Education, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Yishi Fu
- Fujian Key Laboratory of Pathogenic Fungi and Mycotoxins, Key Laboratory of Biopesticide and Chemical Biology of Ministry of Education, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Zhou Fang
- Fujian Key Laboratory of Pathogenic Fungi and Mycotoxins, Key Laboratory of Biopesticide and Chemical Biology of Ministry of Education, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Zhangling Xu
- Fujian Key Laboratory of Pathogenic Fungi and Mycotoxins, Key Laboratory of Biopesticide and Chemical Biology of Ministry of Education, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Genli Ma
- Fujian Key Laboratory of Pathogenic Fungi and Mycotoxins, Key Laboratory of Biopesticide and Chemical Biology of Ministry of Education, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Shihua Wang
- Fujian Key Laboratory of Pathogenic Fungi and Mycotoxins, Key Laboratory of Biopesticide and Chemical Biology of Ministry of Education, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
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24
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Fountain JC, Koh J, Yang L, Pandey MK, Nayak SN, Bajaj P, Zhuang WJ, Chen ZY, Kemerait RC, Lee RD, Chen S, Varshney RK, Guo B. Proteome analysis of Aspergillus flavus isolate-specific responses to oxidative stress in relationship to aflatoxin production capability. Sci Rep 2018; 8:3430. [PMID: 29467403 PMCID: PMC5821837 DOI: 10.1038/s41598-018-21653-x] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 02/03/2018] [Indexed: 12/24/2022] Open
Abstract
Aspergillus flavus is an opportunistic pathogen of plants such as maize and peanut under conducive conditions such as drought stress resulting in significant aflatoxin production. Drought-associated oxidative stress also exacerbates aflatoxin production by A. flavus. The objectives of this study were to use proteomics to provide insights into the pathogen responses to H2O2-derived oxidative stress, and to identify potential biomarkers and targets for host resistance breeding. Three isolates, AF13, NRRL3357, and K54A with high, moderate, and no aflatoxin production, were cultured in medium supplemented with varying levels of H2O2, and examined using an iTRAQ (Isobaric Tags for Relative and Absolute Quantification) approach. Overall, 1,173 proteins were identified and 220 were differentially expressed (DEPs). Observed DEPs encompassed metabolic pathways including antioxidants, carbohydrates, pathogenicity, and secondary metabolism. Increased lytic enzyme, secondary metabolite, and developmental pathway expression in AF13 was correlated with oxidative stress tolerance, likely assisting in plant infection and microbial competition. Elevated expression of energy and cellular component production in NRRL3357 and K54A implies a focus on oxidative damage remediation. These trends explain isolate-to-isolate variation in oxidative stress tolerance and provide insights into mechanisms relevant to host plant interactions under drought stress allowing for more targeted efforts in host resistance research.
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Affiliation(s)
- Jake C Fountain
- Department of Plant Pathology, University of Georgia, Tifton, GA, USA.,USDA-ARS Crop Protection and Management Research Unit, Tifton, GA, USA.,Center of Excellence in Genomics & Systems Biology, International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Telangana, India
| | - Jin Koh
- Department of Biology, Genetics Institute, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL, USA
| | - Liming Yang
- Department of Plant Pathology, University of Georgia, Tifton, GA, USA.,USDA-ARS Crop Protection and Management Research Unit, Tifton, GA, USA.,College of Biology and Environmental Science, Nanjing Forestry University, Nanjing, China
| | - Manish K Pandey
- Center of Excellence in Genomics & Systems Biology, International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Telangana, India
| | - Spurthi N Nayak
- Center of Excellence in Genomics & Systems Biology, International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Telangana, India
| | - Prasad Bajaj
- Center of Excellence in Genomics & Systems Biology, International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Telangana, India
| | - Wei-Jian Zhuang
- College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Zhi-Yuan Chen
- Department of Plant Pathology and Crop Physiology, Louisiana State University, Baton Rouge, LA, USA
| | - Robert C Kemerait
- Department of Plant Pathology, University of Georgia, Tifton, GA, USA
| | - R Dewey Lee
- Department of Crop and Soil Sciences, University of Georgia, Tifton, GA, USA
| | - Sixue Chen
- Department of Biology, Genetics Institute, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL, USA
| | - Rajeev K Varshney
- Center of Excellence in Genomics & Systems Biology, International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Telangana, India
| | - Baozhu Guo
- USDA-ARS Crop Protection and Management Research Unit, Tifton, GA, USA.
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25
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Yang L, Fountain JC, Ji P, Ni X, Chen S, Lee RD, Kemerait RC, Guo B. Deciphering drought-induced metabolic responses and regulation in developing maize kernels. PLANT BIOTECHNOLOGY JOURNAL 2018; 16:1616-1628. [PMID: 29431900 PMCID: PMC6097124 DOI: 10.1111/pbi.12899] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 01/31/2018] [Accepted: 02/03/2018] [Indexed: 05/07/2023]
Abstract
Drought stress conditions decrease maize growth and yield, and aggravate preharvest aflatoxin contamination. While several studies have been performed on mature kernels responding to drought stress, the metabolic profiles of developing kernels are not as well characterized, particularly in germplasm with contrasting resistance to both drought and mycotoxin contamination. Here, following screening for drought tolerance, a drought-sensitive line, B73, and a drought-tolerant line, Lo964, were selected and stressed beginning at 14 days after pollination. Developing kernels were sampled 7 and 14 days after drought induction (DAI) from both stressed and irrigated plants. Comparative biochemical and metabolomic analyses profiled 409 differentially accumulated metabolites. Multivariate statistics and pathway analyses showed that drought stress induced an accumulation of simple sugars and polyunsaturated fatty acids and a decrease in amines, polyamines and dipeptides in B73. Conversely, sphingolipid, sterol, phenylpropanoid and dipeptide metabolites accumulated in Lo964 under drought stress. Drought stress also resulted in the greater accumulation of reactive oxygen species (ROS) and aflatoxin in kernels of B73 in comparison with Lo964 implying a correlation in their production. Overall, field drought treatments disordered a cascade of normal metabolic programming during development of maize kernels and subsequently caused oxidative stress. The glutathione and urea cycles along with the metabolism of carbohydrates and lipids for osmoprotection, membrane maintenance and antioxidant protection were central among the drought stress responses observed in developing kernels. These results also provide novel targets to enhance host drought tolerance and disease resistance through the use of biotechnologies such as transgenics and genome editing.
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Affiliation(s)
- Liming Yang
- USDA‐ARS, Crop Protection and Management Research UnitTiftonGAUSA
- Department of Plant PathologyUniversity of GeorgiaTiftonGAUSA
- College of Biology and the EnvironmentNanjing Forestry UniversityNanjingJiangsuChina
| | - Jake C. Fountain
- USDA‐ARS, Crop Protection and Management Research UnitTiftonGAUSA
- Department of Plant PathologyUniversity of GeorgiaTiftonGAUSA
| | - Pingsheng Ji
- Department of Plant PathologyUniversity of GeorgiaTiftonGAUSA
| | - Xinzhi Ni
- USDA‐ARS, Crop Genetics and Breeding Research UnitTiftonGAUSA
| | - Sixue Chen
- Department of Biology, Genetics Institute, and Plant Molecular & Cellular Biology ProgramUniversity of FloridaGainesvilleFLUSA
| | - Robert D. Lee
- Department of Crop and Soil SciencesUniversity of GeorgiaTiftonGAUSA
| | | | - Baozhu Guo
- USDA‐ARS, Crop Protection and Management Research UnitTiftonGAUSA
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26
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Li T, Gong L, Jiang G, Wang Y, Gupta VK, Qu H, Duan X, Wang J, Jiang Y. Carbon Sources Influence Fumonisin Production inFusarium proliferatum. Proteomics 2017; 17. [DOI: 10.1002/pmic.201700070] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 07/21/2017] [Indexed: 01/05/2023]
Affiliation(s)
- Taotao Li
- Key Laboratory of Plant Resource Conservation and Sustainable Utilization South China Botanical Garden; Chinese Academy of Sciences; Guangzhou P. R. China
- Guangdong Provincial Key Laboratory of Applied Botany South China Botanical Garden; Chinese Academy of Sciences; Guangzhou P. R. China
| | - Liang Gong
- Key Laboratory of Plant Resource Conservation and Sustainable Utilization South China Botanical Garden; Chinese Academy of Sciences; Guangzhou P. R. China
- Guangdong Provincial Key Laboratory of Applied Botany South China Botanical Garden; Chinese Academy of Sciences; Guangzhou P. R. China
| | - Guoxiang Jiang
- Key Laboratory of Plant Resource Conservation and Sustainable Utilization South China Botanical Garden; Chinese Academy of Sciences; Guangzhou P. R. China
- Guangdong Provincial Key Laboratory of Applied Botany South China Botanical Garden; Chinese Academy of Sciences; Guangzhou P. R. China
| | - Yong Wang
- Zhong Shan Entry-Exit Inspection and Quarantine Bureau; Zhongshan P. R. China
| | - Vijai Kumar Gupta
- School of Science; Department of Chemistry and Biotechnology ERA Chair of Green Chemistry; Tallinn University of Technology; Tallinn Estonia
| | - Hongxia Qu
- Key Laboratory of Plant Resource Conservation and Sustainable Utilization South China Botanical Garden; Chinese Academy of Sciences; Guangzhou P. R. China
- Guangdong Provincial Key Laboratory of Applied Botany South China Botanical Garden; Chinese Academy of Sciences; Guangzhou P. R. China
| | - Xuewu Duan
- Key Laboratory of Plant Resource Conservation and Sustainable Utilization South China Botanical Garden; Chinese Academy of Sciences; Guangzhou P. R. China
- Guangdong Provincial Key Laboratory of Applied Botany South China Botanical Garden; Chinese Academy of Sciences; Guangzhou P. R. China
| | - Jiasheng Wang
- Department of Environmental Health Science College of Public Health; University of Georgia; Athens GA USA
| | - Yueming Jiang
- Key Laboratory of Plant Resource Conservation and Sustainable Utilization South China Botanical Garden; Chinese Academy of Sciences; Guangzhou P. R. China
- Guangdong Provincial Key Laboratory of Applied Botany South China Botanical Garden; Chinese Academy of Sciences; Guangzhou P. R. China
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27
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Zhang C, Selvaraj JN, Yang Q, Liu Y. A Survey of Aflatoxin-Producing Aspergillus sp. from Peanut Field Soils in Four Agroecological Zones of China. Toxins (Basel) 2017; 9:E40. [PMID: 28117685 PMCID: PMC5308272 DOI: 10.3390/toxins9010040] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 01/05/2017] [Accepted: 01/06/2017] [Indexed: 11/20/2022] Open
Abstract
Peanut pods are easily infected by aflatoxin-producing Aspergillus sp.ecies from field soil. To assess the aflatoxin-producing Aspergillus sp. in different peanut field soils, 344 aflatoxin-producing Aspergillus strains were isolated from 600 soil samples of four agroecological zones in China (the Southeast coastal zone (SEC), the Yangtze River zone (YZR), the Yellow River zone (YR) and the Northeast zone (NE)). Nearly 94.2% (324/344) of strains were A. flavus and 5.8% (20/344) of strains were A. parasiticus. YZR had the highest population density of Aspergillus sp. and positive rate of aflatoxin production in isolated strains (1039.3 cfu·g-1, 80.7%), the second was SEC (191.5 cfu·g-1, 48.7%), the third was YR (26.5 cfu·g-1, 22.7%), and the last was NE (2.4 cfu·g-1, 6.6%). The highest risk of AFB₁ contamination on peanut was in YZR which had the largest number of AFB₁ producing isolates in 1g soil, followed by SEC and YR, and the lowest was NE. The potential risk of AFB₁ contamination in peanuts can increase with increasing population density and a positive rate of aflatoxin-producing Aspergillus sp. in field soils, suggesting that reducing aflatoxigenic Aspergillus sp. in field soils could prevent AFB₁ contamination in peanuts.
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Affiliation(s)
- Chushu Zhang
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences/Key Laboratory of Agro-Products Processing, Ministry of Agriculture, Beijing 100193, China.
- Shandong Peanut Research Institute, Qingdao 266100, China.
| | - Jonathan Nimal Selvaraj
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences/Key Laboratory of Agro-Products Processing, Ministry of Agriculture, Beijing 100193, China.
| | - Qingli Yang
- Qingdao Agricultural University, Qingdao 266109, China.
| | - Yang Liu
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences/Key Laboratory of Agro-Products Processing, Ministry of Agriculture, Beijing 100193, China.
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28
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Fountain JC, Bajaj P, Nayak SN, Yang L, Pandey MK, Kumar V, Jayale AS, Chitikineni A, Lee RD, Kemerait RC, Varshney RK, Guo B. Responses of Aspergillus flavus to Oxidative Stress Are Related to Fungal Development Regulator, Antioxidant Enzyme, and Secondary Metabolite Biosynthetic Gene Expression. Front Microbiol 2016; 7:2048. [PMID: 28066369 PMCID: PMC5175028 DOI: 10.3389/fmicb.2016.02048] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2016] [Accepted: 12/06/2016] [Indexed: 12/21/2022] Open
Abstract
The infection of maize and peanut with Aspergillus flavus and subsequent contamination with aflatoxin pose a threat to global food safety and human health, and is exacerbated by drought stress. Drought stress-responding compounds such as reactive oxygen species (ROS) are associated with fungal stress responsive signaling and secondary metabolite production, and can stimulate the production of aflatoxin by A. flavus in vitro. These secondary metabolites have been shown to possess diverse functions in soil-borne fungi including antibiosis, competitive inhibition of other microbes, and abiotic stress alleviation. Previously, we observed that isolates of A. flavus showed differences in oxidative stress tolerance which correlated with their aflatoxin production capabilities. In order to better understand these isolate-specific oxidative stress responses, we examined the transcriptional responses of field isolates of A. flavus with varying levels of aflatoxin production (NRRL3357, AF13, and Tox4) to H2O2-induced oxidative stress using an RNA sequencing approach. These isolates were cultured in an aflatoxin-production conducive medium amended with various levels of H2O2. Whole transcriptomes were sequenced using an Illumina HiSeq platform with an average of 40.43 million filtered paired-end reads generated for each sample. The obtained transcriptomes were then used for differential expression, gene ontology, pathway, and co-expression analyses. Isolates which produced higher levels of aflatoxin tended to exhibit fewer differentially expressed genes than isolates with lower levels of production. Genes found to be differentially expressed in response to increasing oxidative stress included antioxidant enzymes, primary metabolism components, antibiosis-related genes, and secondary metabolite biosynthetic components specifically for aflatoxin, aflatrem, and kojic acid. The expression of fungal development-related genes including aminobenzoate degradation genes and conidiation regulators were found to be regulated in response to increasing stress. Aflatoxin biosynthetic genes and antioxidant enzyme genes were also found to be co-expressed and highly correlated with fungal biomass under stress. This suggests that these secondary metabolites may be produced as part of coordinated oxidative stress responses in A. flavus along with antioxidant enzyme gene expression and developmental regulation.
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Affiliation(s)
- Jake C Fountain
- Department of Plant Pathology, University of GeorgiaTifton, GA, USA; United States Department of Agriculture, Agricultural Research Service Crop Protection and Management Research UnitTifton, GA, USA
| | - Prasad Bajaj
- International Crop Research Institute for the Semi-Arid Tropics Hyderabad, India
| | - Spurthi N Nayak
- International Crop Research Institute for the Semi-Arid Tropics Hyderabad, India
| | - Liming Yang
- Department of Plant Pathology, University of GeorgiaTifton, GA, USA; United States Department of Agriculture, Agricultural Research Service Crop Protection and Management Research UnitTifton, GA, USA
| | - Manish K Pandey
- International Crop Research Institute for the Semi-Arid Tropics Hyderabad, India
| | - Vinay Kumar
- International Crop Research Institute for the Semi-Arid Tropics Hyderabad, India
| | - Ashwin S Jayale
- International Crop Research Institute for the Semi-Arid Tropics Hyderabad, India
| | - Anu Chitikineni
- International Crop Research Institute for the Semi-Arid Tropics Hyderabad, India
| | - Robert D Lee
- Department of Crop and Soil Sciences, University of Georgia Tifton, GA, USA
| | - Robert C Kemerait
- Department of Plant Pathology, University of Georgia Tifton, GA, USA
| | - Rajeev K Varshney
- International Crop Research Institute for the Semi-Arid Tropics Hyderabad, India
| | - Baozhu Guo
- United States Department of Agriculture, Agricultural Research Service Crop Protection and Management Research Unit Tifton, GA, USA
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29
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Fountain JC, Bajaj P, Pandey M, Nayak SN, Yang L, Kumar V, Jayale AS, Chitikineni A, Zhuang W, Scully BT, Lee RD, Kemerait RC, Varshney RK, Guo B. Oxidative stress and carbon metabolism influence Aspergillus flavus transcriptome composition and secondary metabolite production. Sci Rep 2016; 6:38747. [PMID: 27941917 PMCID: PMC5150527 DOI: 10.1038/srep38747] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 11/15/2016] [Indexed: 11/09/2022] Open
Abstract
Contamination of crops with aflatoxin is a serious global threat to food safety. Aflatoxin production by Aspergillus flavus is exacerbated by drought stress in the field and by oxidative stress in vitro. We examined transcriptomes of three toxigenic and three atoxigenic isolates of A. flavus in aflatoxin conducive and non-conducive media with varying levels of H2O2 to investigate the relationship of secondary metabolite production, carbon source, and oxidative stress. We found that toxigenic and atoxigenic isolates employ distinct mechanisms to remediate oxidative damage, and that carbon source affected the isolates’ expression profiles. Iron metabolism, monooxygenases, and secondary metabolism appeared to participate in isolate oxidative responses. The results suggest that aflatoxin and aflatrem biosynthesis may remediate oxidative stress by consuming excess oxygen and that kojic acid production may limit iron-mediated, non-enzymatic generation of reactive oxygen species. Together, secondary metabolite production may enhance A. flavus stress tolerance, and may be reduced by enhancing host plant tissue antioxidant capacity though genetic improvement by breeding selection.
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Affiliation(s)
- Jake C Fountain
- Department of Plant Pathology, University of Georgia, Tifton, GA, USA.,USDA-ARS Crop Protection and Management Research Unit, Tifton, GA, USA
| | - Prasad Bajaj
- International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana, India
| | - Manish Pandey
- International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana, India
| | - Spurthi N Nayak
- International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana, India
| | - Liming Yang
- Department of Plant Pathology, University of Georgia, Tifton, GA, USA.,USDA-ARS Crop Protection and Management Research Unit, Tifton, GA, USA
| | - Vinay Kumar
- International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana, India
| | - Ashwin S Jayale
- International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana, India
| | - Anu Chitikineni
- International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana, India
| | - Weijian Zhuang
- Fujian Agricultural and Forestry University, Fuzhou, Fujian, China
| | - Brian T Scully
- USDA-ARS US Horticultural Research Laboratory, Fort Pierce, FL, USA
| | - R Dewey Lee
- Department of Crop and Soil Sciences, University of Georgia, Tifton, GA, USA
| | - Robert C Kemerait
- Department of Plant Pathology, University of Georgia, Tifton, GA, USA
| | - Rajeev K Varshney
- International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana, India
| | - Baozhu Guo
- USDA-ARS Crop Protection and Management Research Unit, Tifton, GA, USA
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