1
|
Yu M, Zhou X, Chen D, Jiao Y, Han G, Tao F. HacA, a key transcription factor for the unfolded protein response, is required for fungal development, aflatoxin biosynthesis and pathogenicity of Aspergillus flavus. Int J Food Microbiol 2024; 417:110693. [PMID: 38653122 DOI: 10.1016/j.ijfoodmicro.2024.110693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2023] [Revised: 03/16/2024] [Accepted: 04/02/2024] [Indexed: 04/25/2024]
Abstract
Aspergillus flavus is a fungus notorious for contaminating food and feed with aflatoxins. As a saprophytic fungus, it secretes large amounts of enzymes to access nutrients, making endoplasmic reticulum (ER) homeostasis important for protein folding and secretion. The role of HacA, a key transcription factor in the unfolded protein response pathway, remains poorly understood in A. flavus. In this study, the hacA gene in A. flavus was knockout. Results showed that the absence of hacA led to a decreased pathogenicity of the strain, as it failed to colonize intact maize kernels. This may be due to retarded vegetable growth, especially the abnormal development of swollen tips and shorter hyphal septa. Deletion of hacA also hindered conidiogenesis and sclerotial development. Notably, the mutant strain failed to produce aflatoxin B1. Moreover, compared to the wild type, the mutant strain showed increased sensitivity to ER stress inducer such as Dithiothreitol (DTT), and heat stress. It also displayed heightened sensitivity to other environmental stresses, including cell wall, osmotic, and pH stresses. Further transcriptomic analysis revealed the involvement of the hacA in numerous biological processes, including filamentous growth, asexual reproduction, mycotoxin biosynthetic process, signal transduction, budding cell apical bud growth, invasive filamentous growth, response to stimulus, and so on. Taken together, HacA plays a vital role in fungal development, pathogenicity and aflatoxins biosynthesis. This highlights the potential of targeting hacA as a novel approach for early prevention of A. flavus contamination.
Collapse
Affiliation(s)
- Min Yu
- School of Life Sciences, Anhui Agricultural University, Hefei 230036, China
| | - Xiaoling Zhou
- School of Life Sciences, Anhui Agricultural University, Hefei 230036, China
| | - Dongyue Chen
- School of Life Sciences, Anhui Agricultural University, Hefei 230036, China
| | - Yuan Jiao
- School of Life Sciences, Anhui Agricultural University, Hefei 230036, China
| | - Guomin Han
- School of Life Sciences, Anhui Agricultural University, Hefei 230036, China; National Engineering Laboratory of Crop Stress Resistance Breeding, Anhui Agricultural University, Hefei 230036, China
| | - Fang Tao
- School of Life Sciences, Anhui Agricultural University, Hefei 230036, China.
| |
Collapse
|
2
|
El-Dawy EGAM, Gherbawy YA, Hussein MA. Characterization of Aspergillus section Flavi associated with stored grains. Mycotoxin Res 2024; 40:187-202. [PMID: 38231446 PMCID: PMC10834605 DOI: 10.1007/s12550-023-00514-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Revised: 12/12/2023] [Accepted: 12/14/2023] [Indexed: 01/18/2024]
Abstract
Increased frequencies of Aspergillus section Flavi and aflatoxins in cereal grains have been seen in recent years due to changes in climate circumstances, such as high temperatures and drought. To assess the microbiological risks of contamination, it is critical to have a reliable and accurate means of identifying the fungi. The main goal of this study was to characterize Aspergillus species from section Flavi obtained from twenty-three samples of barley and maize grains, gathered from different markets in Qena, Egypt, using morphological and molecular techniques. Twenty-three isolates were chosen, one isolate from each sample; they were identified as A. aflatoxiformans (4 isolates), A. flavus (18), and A. parasiticus (1). The existence of four aflatoxin biosynthesis genes was also investigated in relation to the strains' ability to produce total aflatoxins and aflatoxin B1, focusing on the regulatory gene aflR and the structural genes aflD and aflM. All strains producing aflatoxins were linked to the presence of aflR1 and/or aflR2, except two isolates that exhibited aflatoxins but from which aflR1 or aflR2 were not detected, which may be due to one or more missing or unstudied additional genes involved in aflatoxin production. AflD and aflM genes were amplified by 10 and 9 isolates, respectively. Five samples of barley and maize were contaminated by aflatoxins. Fifteen isolates were positive for producing total aflatoxins in the range of 0.1-240 ppm. Antagonistic activity of Trichoderma viride against A. flavus (F5) was assessed at 31.3%. Trichoderma reduced total aflatoxins in all treated seeds, particularly those subjected to Trichoderma formulation.
Collapse
Affiliation(s)
- Eman G A M El-Dawy
- Botany and Microbiology Department, Faculty of Science, South Valley University, Qena, Egypt.
- Applied and Environmental Microbiology Center, South Valley University, Qena, Egypt.
| | - Youssuf A Gherbawy
- Botany and Microbiology Department, Faculty of Science, South Valley University, Qena, Egypt
- Applied and Environmental Microbiology Center, South Valley University, Qena, Egypt
| | - Mohamed A Hussein
- Botany and Microbiology Department, Faculty of Science, South Valley University, Qena, Egypt
- Applied and Environmental Microbiology Center, South Valley University, Qena, Egypt
| |
Collapse
|
3
|
Qu S, Chi SD, He ZM. The Development of Aspergillus flavus and Biosynthesis of Aflatoxin B1 are Regulated by the Golgi-Localized Mn 2+ Transporter Pmr1. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:1276-1291. [PMID: 38179648 DOI: 10.1021/acs.jafc.3c06964] [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: 01/06/2024]
Abstract
Microorganisms rely on diverse ion transport and trace elements to sustain growth, development, and secondary metabolism. Manganese (Mn2+) is essential for various biological processes and plays a crucial role in the metabolism of human cells, plants, and yeast. In Aspergillus flavus, we confirmed that Pmr1 localized in cis- and medial-Golgi compartments was critical in facilitating Mn2+ transport, fungal growth, development, secondary metabolism, and glycosylation. In comparison to the wild type, the Δpmr1 mutant displayed heightened sensitivity to environmental stress, accompanied by inhibited synthesis of aflatoxin B1, kojic acid, and a substantial reduction in pathogenicity toward peanuts and maize. Interestingly, the addition of exogenous Mn2+ effectively rectified the developmental and secondary metabolic defects in the Δpmr1 mutant. However, Mn2+ supplement failed to restore the growth and development of the Δpmr1Δgdt1 double mutant, which indicated that the Gdt1 compensated for the functional deficiency of pmr1. In addition, our results showed that pmr1 knockout leads to an upregulation of O-glycosyl-N-acetylglucose (O-GlcNAc) and O-GlcNAc transferase (OGT), while Mn2+ supplementation can restore the glycosylation in A. flavus. Collectively, this study indicates that the pmr1 regulates Mn2+ via Golgi and maintains growth and metabolism functions of A. flavus through regulation of the glycosylation.
Collapse
Affiliation(s)
- Su Qu
- School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Sheng-Da Chi
- School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Zhu-Mei He
- School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
- School of Medicine, Sun Yat-sen University, Shenzhen 518107, China
| |
Collapse
|
4
|
Wang W, Liu Y, Duan S, Bai N, Zhu M, Yang J. Cellular communication and fusion regulate cell fusion, trap morphogenesis, conidiation, and secondary metabolism in Arthrobotrys oligospora. Microbiol Res 2024; 278:127516. [PMID: 37857124 DOI: 10.1016/j.micres.2023.127516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 10/05/2023] [Accepted: 10/10/2023] [Indexed: 10/21/2023]
Abstract
Signal-mediated cell fusion is vital for colony development in filamentous fungi. Arthrobotrys oligospora is a representative nematode-trapping (NT) fungus that produces adhesive networks (traps) to capture nematodes. Here, we characterized Aoadv-1, Aoso, Aoham-6, and Aoham-5 of A. oligospora, homologs of proteins involved in cellular communication and fusion in the model fungus Neurospora crassa. The deletion of four genes resulted in the complete loss of cell fusion, and traps produced by mutants did not close to form mycelial rings but were still capable of capturing nematodes. The absence of these genes inhibits aerial mycelial extension, slows colony growth, and increases mycelial branching. In addition, the mutants showed reduced sporulation capacity and tolerance to oxidative stress, increased sensitivity to SDS, and disturbed lipid droplet accumulation and autophagy. In addition, transcriptome and metabolomic analyses suggested that Aoadv-1 and Aoso are involved in multiple cellular processes and secondary metabolism. Our results revealed that Aoadv-1, Aoso, Aoham-6, and Aoham-5 regulate mycelial growth and trap morphogenesis through cell fusion, which contributed to elucidating the molecular mechanisms of cellular communication regulating mycelial development and trap morphogenesis in NT fungi.
Collapse
Affiliation(s)
- Wenjie Wang
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Key Laboratory for Southwest Microbial Diversity of the Ministry of Education, and School of Life Science, Yunnan University, Kunming 650032, China
| | - Yankun Liu
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Key Laboratory for Southwest Microbial Diversity of the Ministry of Education, and School of Life Science, Yunnan University, Kunming 650032, China
| | - Shipeng Duan
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Key Laboratory for Southwest Microbial Diversity of the Ministry of Education, and School of Life Science, Yunnan University, Kunming 650032, China
| | - Na Bai
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Key Laboratory for Southwest Microbial Diversity of the Ministry of Education, and School of Life Science, Yunnan University, Kunming 650032, China
| | - Meichen Zhu
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Key Laboratory for Southwest Microbial Diversity of the Ministry of Education, and School of Life Science, Yunnan University, Kunming 650032, China
| | - Jinkui Yang
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Key Laboratory for Southwest Microbial Diversity of the Ministry of Education, and School of Life Science, Yunnan University, Kunming 650032, China.
| |
Collapse
|
5
|
Jesmin R, Cary JW, Lebar MD, Majumdar R, Gummadidala PM, Dias T, Chandler S, Basu P, Decho AW, Keller NP, Chanda A. Vibrio gazogenes-dependent disruption of aflatoxin biosynthesis in Aspergillus flavus: the connection with endosomal uptake and hyphal morphogenesis. Front Microbiol 2023; 14:1208961. [PMID: 37744918 PMCID: PMC10516221 DOI: 10.3389/fmicb.2023.1208961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Accepted: 08/07/2023] [Indexed: 09/26/2023] Open
Abstract
Aflatoxins, a family of fungal secondary metabolites, are toxic and carcinogenic compounds that pose an enormous threat to global food safety and agricultural sustainability. Specifically agricultural products in African, Southeast Asian and hot and humid regions of American countries suffer most damage from aflatoxin producing molds due to the ideal climate conditions promoting their growth. Our recent studies suggest that Vibrio gazogenes (Vg), an estuarine bacterium non-pathogenic to plants and humans, can significantly inhibit aflatoxin biosynthesis in the producers. In this study, we investigated the mechanism underlying Vg-dependent aflatoxin inhibition using the prominent aflatoxin producer, Aspergillus flavus. We show that aflatoxin inhibition upon Vg treatment was associated with fungal uptake of Vg-prodigiosin, a red pigment, which was consistently visible inside fungal hyphae during treatment. The association of prodigiosin with aflatoxin inhibition was further evident as Serratia marcescens, another prodigiosin producer, significantly inhibited aflatoxin, while non-producers like Escherichia coli, Staphylococcus aureus, Vibrio harveyi, and Vibrio fischeri did not. Also, pure prodigiosin significantly inhibited aflatoxin biosynthesis. Endocytosis inhibitors, filipin and natamycin, reduced the Vg-prodigiosin uptake by the fungus leading to a significant increase in aflatoxin production, suggesting that uptake is endocytosis-dependent. The Vg treatment also reduced hyphal fusion (>98% inhibition) and branching, which are both endosome-dependent processes. Our results, therefore, collectively support our theory that Vg-associated aflatoxin inhibition is mediated by an endocytosis-dependent uptake of Vg-prodigiosin, which possibly leads to a disruption of normal endosomal functions.
Collapse
Affiliation(s)
| | - Jeffrey W. Cary
- Food and Feed Safety Research Unit, USDA/ARS, Southern Regional Research Center, New Orleans, LA, United States
| | - Matthew D. Lebar
- Food and Feed Safety Research Unit, USDA/ARS, Southern Regional Research Center, New Orleans, LA, United States
| | - Rajtilak Majumdar
- Northwest Irrigation and Soils Research, United States Department of Agriculture, Kimberly, ID, United States
| | - Phani M. Gummadidala
- University of North Carolina School of Medicine, Chapell Hill, NC, United States
| | - Travis Dias
- University of South Carolina School of Medicine, Greenville, NC, United States
| | - Savannah Chandler
- Department of Environmental Health Sciences, University of South Carolina, Columbia, SC, United States
| | - Paramita Basu
- New York College of Podiatric Medicine, New York, NY, United States
| | - Alan W. Decho
- Department of Environmental Health Sciences, University of South Carolina, Columbia, SC, United States
| | - Nancy P. Keller
- Department of Medical Microbiology and Immunology, Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, United States
| | | |
Collapse
|
6
|
Tannous J, Cosetta CM, Drott MT, Rush TA, Abraham PE, Giannone RJ, Keller NP, Wolfe BE. LaeA-Regulated Fungal Traits Mediate Bacterial Community Assembly. mBio 2023:e0076923. [PMID: 37162223 DOI: 10.1128/mbio.00769-23] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023] Open
Abstract
Potent antimicrobial metabolites are produced by filamentous fungi in pure culture, but their ecological functions in nature are often unknown. Using an antibacterial Penicillium isolate and a cheese rind microbial community, we demonstrate that a fungal specialized metabolite can regulate the diversity of bacterial communities. Inactivation of the global regulator, LaeA, resulted in the loss of antibacterial activity in the Penicillium isolate. Cheese rind bacterial communities assembled with the laeA deletion strain had significantly higher bacterial abundances than the wild-type strain. RNA-sequencing and metabolite profiling demonstrated a striking reduction in the expression and production of the natural product pseurotin in the laeA deletion strain. Inactivation of a core gene in the pseurotin biosynthetic cluster restored bacterial community composition, confirming the role of pseurotins in mediating bacterial community assembly. Our discovery demonstrates how global regulators of fungal transcription can control the assembly of bacterial communities and highlights an ecological role for a widespread class of fungal specialized metabolites. IMPORTANCE Cheese rinds are economically important microbial communities where fungi can impact food quality and aesthetics. The specific mechanisms by which fungi can regulate bacterial community assembly in cheeses, other fermented foods, and microbiomes in general are largely unknown. Our study highlights how specialized metabolites secreted by a Penicillium species can mediate cheese rind development via differential inhibition of bacterial community members. Because LaeA regulates specialized metabolites and other ecologically relevant traits in a wide range of filamentous fungi, this global regulator may have similar impacts in other fungus-dominated microbiomes.
Collapse
Affiliation(s)
- Joanna Tannous
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Casey M Cosetta
- Department of Biology, Tufts University, Medford, Massachusetts, USA
| | - Milton T Drott
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, Wisconsin, USA
- USDA-ARS Cereal Disease Laboratory, St. Paul, Minnesota, USA
| | - Tomás A Rush
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Paul E Abraham
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Richard J Giannone
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Nancy P Keller
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Benjamin E Wolfe
- Department of Biology, Tufts University, Medford, Massachusetts, USA
| |
Collapse
|
7
|
Palos-Fernández R, Turrà D, Pietro AD. The Gal4-Type Transcription Factor Pro1 Integrates Inputs from Two Different MAPK Cascades to Regulate Development in the Fungal Pathogen Fusarium oxysporum. J Fungi (Basel) 2022; 8:jof8121242. [PMID: 36547575 PMCID: PMC9781702 DOI: 10.3390/jof8121242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Revised: 11/19/2022] [Accepted: 11/21/2022] [Indexed: 11/25/2022] Open
Abstract
Mitogen-activated protein kinase (MAPK) signaling pathways control fundamental aspects of growth and development in fungi. In the soil-inhabiting ascomycete Fusarium oxysporum, which causes vascular wilt disease in more than a hundred crops, the MAPKs Fmk1 and Mpk1 regulate an array of developmental and virulence-related processes. The downstream components mediating these disparate functions are largely unknown. Here we find that the GATA-type transcription factor Pro1 integrates signals from both MAPK pathways to control a subset of functions, including quorum sensing, hyphal fusion and chemotropism. By contrast, Pro1 is dispensable for other downstream processes such as invasive hyphal growth and virulence, or response to cell wall stress. We further show that regulation of Pro1 activity by these upstream pathways occurs at least in part at the level of transcription. Besides the MAPK pathways, upstream regulators of Pro1 transcription also include the Velvet regulatory complex, the signaling protein Soft (Fso1) and the transcription factor Ste12 which was previously shown to act downstream of Fmk1. Collectively, our results reveal a role of Pro1 in integrating the outputs from different signaling pathways of F. oxysporum thereby mediating key developmental decisions in this important fungal pathogen.
Collapse
Affiliation(s)
| | - David Turrà
- Center for Studies on Bioinspired Agro-Enviromental Technology, Department of Agriculture, Università di Napoli Federico II, 80055 Portici, Italy
| | - Antonio Di Pietro
- Departamento de Genética, Universidad de Córdoba, 14014 Córdoba, Spain
- Correspondence: ; Tel.: +34-957-218-981
| |
Collapse
|
8
|
Ge J, Zhang Z, Li Y, Hu Z, He B, Li Y, Zeng B, Jiang C. Inhibition of AoAur1 increases mycelial growth, hyphal fusion and improves physiological adaptation to high-temperature stress in Aspergillus oryzae. Arch Microbiol 2022; 204:477. [PMID: 35829968 DOI: 10.1007/s00203-022-03075-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 06/03/2022] [Accepted: 06/13/2022] [Indexed: 11/02/2022]
Abstract
Inositol phosphorylceramide (IPC) participates in hyphal growth and serves as a signaling molecule that enables fungi to adapt to diverse environments. Here, a gene, encodes IPC synthase, was identified from the Aspergillus oryzae 3.042 genome and designated AoAur1. The characteristics, phylogenetic evolution, and resistance to aureobasidin A of AoAur1 were analyzed. The expression pattern of AoAur1 was markedly downregulated under temperature stress. Additionally, an RNAi-AoAur1 strain in which the AoAur1 expression was inhibited had mycelial that grew more quickly, had a higher frequency of hyphal fusion, and was more resistant to high-temperature stress than the control. Gene expression profiles showed that the genes related to IPC biosynthesis were obviously downregulated, while AoCerS, which participates in dihydroceramide biosynthesis, increased in the RNAi-AoAur1 strain at the three temperature treatments. A metabolomic analysis revealed that the intracellular IPC content decreased, and the accumulation of dihydroceramide and galactosylceramide increased significantly in the RNAi-AoAur1 strain. Thus, the inhibition of AoAur1 reduced IPC level followed by an increase in the contents of dihydroceramide and galactosylceramide that promote mycelial growth and the formation of spores in the RNAi-AoAur1 strain. Interestingly, the inhibition of AoAur1 also induced the expression of hyphal fusion-related genes, which promote hyphal fusion, thus, contributing to the transduction of stress signal to enhance the ability of cells to adapt to temperature stress. Our results demonstrated that the downregulation of AoAur1 and a decrease in the accumulation of IPC is one of the mechanisms that enables A. oryzae to adapt low- and high-temperature stress.
Collapse
Affiliation(s)
- Jinxin Ge
- Jiangxi Key Laboratory of Bioprocess Engineering and Co-Innovation Center for In-Vitro Diagnostic Reagents and Devices of Jiangxi Province, College of Life Sciences, Jiangxi Science and Technology Normal University, Nanchang, 330013, China
| | - Zhe Zhang
- Jiangxi Key Laboratory of Bioprocess Engineering and Co-Innovation Center for In-Vitro Diagnostic Reagents and Devices of Jiangxi Province, College of Life Sciences, Jiangxi Science and Technology Normal University, Nanchang, 330013, China
| | - Yuan Li
- Jiangxi Key Laboratory of Bioprocess Engineering and Co-Innovation Center for In-Vitro Diagnostic Reagents and Devices of Jiangxi Province, College of Life Sciences, Jiangxi Science and Technology Normal University, Nanchang, 330013, China
| | - Zhihong Hu
- Jiangxi Key Laboratory of Bioprocess Engineering and Co-Innovation Center for In-Vitro Diagnostic Reagents and Devices of Jiangxi Province, College of Life Sciences, Jiangxi Science and Technology Normal University, Nanchang, 330013, China
| | - Bin He
- Jiangxi Key Laboratory of Bioprocess Engineering and Co-Innovation Center for In-Vitro Diagnostic Reagents and Devices of Jiangxi Province, College of Life Sciences, Jiangxi Science and Technology Normal University, Nanchang, 330013, China
| | - Yongkai Li
- Jiangxi Key Laboratory of Bioprocess Engineering and Co-Innovation Center for In-Vitro Diagnostic Reagents and Devices of Jiangxi Province, College of Life Sciences, Jiangxi Science and Technology Normal University, Nanchang, 330013, China
| | - Bin Zeng
- Jiangxi Key Laboratory of Bioprocess Engineering and Co-Innovation Center for In-Vitro Diagnostic Reagents and Devices of Jiangxi Province, College of Life Sciences, Jiangxi Science and Technology Normal University, Nanchang, 330013, China. .,College of Pharmacy, Shenzhen Technology University, Shenzhen, 518000, China.
| | - Chunmiao Jiang
- Jiangxi Key Laboratory of Bioprocess Engineering and Co-Innovation Center for In-Vitro Diagnostic Reagents and Devices of Jiangxi Province, College of Life Sciences, Jiangxi Science and Technology Normal University, Nanchang, 330013, China.
| |
Collapse
|
9
|
Yuan XY, Li JY, Zhi QQ, Chi SD, Qu S, Luo YF, He ZM. SfgA Renders Aspergillus flavus More Stable to the External Environment. J Fungi (Basel) 2022; 8:jof8060638. [PMID: 35736121 PMCID: PMC9224668 DOI: 10.3390/jof8060638] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2022] [Revised: 06/07/2022] [Accepted: 06/08/2022] [Indexed: 02/04/2023] Open
Abstract
sfgA is known as a key negative transcriptional regulator gene of asexual sporulation and sterigmatocystin production in Aspergillus nidulans. However, here, we found that the homolog sfgA gene shows a broad and complex regulatory role in governing growth, conidiation, sclerotia formation, secondary metabolism, and environmental stress responses in Aspergillus flavus. When sfgA was deleted in A. flavus, the fungal growth was slowed, but the conidiation was significantly increased, and the sclerotia formation displayed different behavior at different temperatures, which increased at 30 °C but decreased at 36 °C. In addition, sfgA regulated aflatoxin biosynthesis in a complex way that was associated with the changes in cultured conditions, and the increased production of aflatoxin in the ∆sfgA mutant was associated with a decrease in sclerotia size. Furthermore, the ∆sfgA mutant exhibited sensitivity to osmotic, oxidative, and cell wall stresses but still produced dense conidia. Transcriptome data indicated that numerous development- and secondary-metabolism-related genes were expressed differently when sfgA was deleted. Additionally, we also found that sfgA functions downstream of fluG in A. flavus, which is consistent with the genetic position in FluG-mediated conidiation in A. nidulans. Collectively, sfgA plays a critical role in the development, secondary metabolism, and stress responses of A. flavus, and sfgA renders A. flavus more stable to the external environment.
Collapse
Affiliation(s)
- Xiao-Yu Yuan
- The Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Science, Sun Yat-sen University, Guangzhou 510275, China; (X.-Y.Y.); (J.-Y.L.); (Q.-Q.Z.); (S.-D.C.); (S.Q.)
| | - Jie-Ying Li
- The Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Science, Sun Yat-sen University, Guangzhou 510275, China; (X.-Y.Y.); (J.-Y.L.); (Q.-Q.Z.); (S.-D.C.); (S.Q.)
| | - Qing-Qing Zhi
- The Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Science, Sun Yat-sen University, Guangzhou 510275, China; (X.-Y.Y.); (J.-Y.L.); (Q.-Q.Z.); (S.-D.C.); (S.Q.)
- College of Agriculture and Biology, Zhongkai University of Agriculture and Engineering, Guangzhou 510225, China
| | - Sheng-Da Chi
- The Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Science, Sun Yat-sen University, Guangzhou 510275, China; (X.-Y.Y.); (J.-Y.L.); (Q.-Q.Z.); (S.-D.C.); (S.Q.)
| | - Su Qu
- The Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Science, Sun Yat-sen University, Guangzhou 510275, China; (X.-Y.Y.); (J.-Y.L.); (Q.-Q.Z.); (S.-D.C.); (S.Q.)
| | - Yan-Feng Luo
- Guangdong Jinyinshan Environmental Protection Technology Co., Ltd., Guangzhou 510705, China;
| | - Zhu-Mei He
- The Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Science, Sun Yat-sen University, Guangzhou 510275, China; (X.-Y.Y.); (J.-Y.L.); (Q.-Q.Z.); (S.-D.C.); (S.Q.)
- Correspondence:
| |
Collapse
|
10
|
Abstract
Aspergillus flavusaflR, a gene encoding a Zn(II)2Cys6 DNA-binding domain, is an important transcriptional regulator of the aflatoxin biosynthesis gene cluster. Our previous results of Gene ontology (GO) analysis for the binding sites of AflR in A. flavus suggest that AflR may play an integrative regulatory role. In this study the ΔaflR and overexpression (OE) strains based on the well-established double-crossover recombinational technique were constructed to investigate the integrative function of the aflR gene in A. flavus. The disruption of aflR severely affected the aflatoxin biosynthetic pathway, resulting in a significant decrease in aflatoxin production. The aflatoxin B1 (AFB1) of the ΔaflR strain was 180 ng/mL and aflatoxin B2 (AFB2) was 2.95 ng/mL on YES medium for 5 days, which was 1/1,000 of that produced by the wild-type strain (WT). In addition, the ΔaflR strain produced relatively sparse conidia and a very small number of sclerotia. On the seventh day, the sclerotia yield on each plate of the WT and OE strains exceeded 1,000, while the sclerotial formation of the ΔaflR strain was not detected until 14 days. However, the biosynthesis of cyclopiazonic acid (CPA) was not affected by aflR gene disruption. Transcriptomic analysis of the ΔaflR strain grown on potato dextrose agar (PDA) plates at 0 h, 24 h, and 72 h showed that expression of clustering genes involved in the biosynthesis of aflatoxin was significantly downregulated. Meanwhile, the ΔaflR strain compared with the WT strain showed significant expression differences in genes involved in spore germination, sclerotial development, and carbohydrate metabolism compared to the WT. The results demonstrated that the A. flavusaflR gene also played a positive role in the fungal growth and development in addition to aflatoxin biosynthesis. IMPORTANCE Past studies of the A. flavusaflR gene and its orthologues in related Aspergillus species were solely focused on their roles in secondary metabolism. In this study, we used the ΔaflR and OE strains to demonstrate the role of aflR in growth and development of A. flavus. For the first time, we confirmed that the ΔaflR strain also was defective in production of conidia and sclerotia, asexual propagules of A. flavus. Our transcriptomic analysis further showed that genes involved in spore germination, sclerotial development, aflatoxin biosynssssthesis, and carbohydrate metabolism exhibited significant differences in the ΔaflR strain compared with the WT strain. Our study indicates that AflR not only plays an important role in regulating aflatoxin synthesis but also in playing a positive role in the conidial formation and sclerotial development in A. flavus. This study reveals the critical and positive role of the aflR gene in fungal growth and development, and provides a theoretical basis for the genetic studies of other aspergilli.
Collapse
|
11
|
Xu J, Wang P, Zhou Z, Cotty PJ, Kong Q. Selection of Atoxigenic Aspergillus flavus for Potential Use in Aflatoxin Prevention in Shandong Province, China. J Fungi (Basel) 2021; 7:jof7090773. [PMID: 34575811 PMCID: PMC8472152 DOI: 10.3390/jof7090773] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 08/13/2021] [Accepted: 09/13/2021] [Indexed: 11/17/2022] Open
Abstract
Aspergillus flavus is a common filamentous fungus widely present in the soil, air, and in crops. This facultative pathogen of both animals and plants produces aflatoxins, a group of mycotoxins with strong teratogenic and carcinogenic properties. Peanuts are highly susceptible to aflatoxin contamination and consumption of contaminated peanuts poses serious threats to the health of humans and domestic animals. Currently, the competitive displacement of aflatoxin-producers from agricultural environments by atoxigenic A. flavus is the most effective method of preventing crop aflatoxin contamination. In the current study, 47 isolates of A. flavus collected from peanut samples originating in Shandong Province were characterized with molecular methods and for aflatoxin-producing ability in laboratory studies. Isolates PA04 and PA10 were found to be atoxigenic members of the L strains morphotype. When co-inoculated with A. flavus NRRL3357 at ratios of 1:10, 1:1, and 10:1 (PA04/PA10: NRRL3357), both atoxigenic strains were able to reduce aflatoxin B1 (AFB1) levels, on both culture media and peanut kernels, by up to 90%. The extent to which atoxigenic strains reduced contamination was correlated with the inoculation ratio. Abilities to compete of PA04 and PA10 were also independently verified against local aflatoxin-producer PA37. The results suggest that the two identified atoxigenic strains are good candidates for active ingredients of biocontrol products for the prevention of aflatoxin contamination of peanuts in Shandong Province.
Collapse
Affiliation(s)
- Jia Xu
- School of Food Science and Engineering, Ocean University of China, Qingdao 266003, China; (J.X.); (P.W.); (P.J.C.)
| | - Peng Wang
- School of Food Science and Engineering, Ocean University of China, Qingdao 266003, China; (J.X.); (P.W.); (P.J.C.)
| | - Zehua Zhou
- Food Technology Department, Wageningen University & Research, 6700 AK Wageningen, The Netherlands;
| | - Peter John Cotty
- School of Food Science and Engineering, Ocean University of China, Qingdao 266003, China; (J.X.); (P.W.); (P.J.C.)
| | - Qing Kong
- School of Food Science and Engineering, Ocean University of China, Qingdao 266003, China; (J.X.); (P.W.); (P.J.C.)
- Correspondence: ; Tel.: +86-532-8203-2290; Fax: +86-532-8203-238
| |
Collapse
|
12
|
Li J, Zhi QQ, Zhang J, Yuan XY, Jia LH, Wan YL, Liu QY, Shi JR, He ZM. Synthetic antimicrobial agents inhibit aflatoxin production. Braz J Microbiol 2021; 52:821-835. [PMID: 33447936 DOI: 10.1007/s42770-021-00423-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 01/05/2021] [Indexed: 11/25/2022] Open
Abstract
Antimicrobial peptides (AMPs) are biologically active molecules that can eradicate bacteria by destroying the bacterial membrane structure, causing the bacteria to rupture. However, little is known about the extent and effect of AMPs on filamentous fungi. In this study, we synthesized small molecular polypeptides by an inexpensive heat conjugation approach and examined their effects on the growth of Aspergillus flavus and its secondary metabolism. The antimicrobial agents significantly inhibited aflatoxin production, conidiation, and sclerotia formation in A. flavus. Furthermore, we found that the expression of aflatoxin structural genes was significantly inhibited, and the intracellular reactive oxygen species (ROS) level was reduced. Additionally, the antimicrobial agents can change membrane permeability. Overall, our results demonstrated that antimicrobial agents, safe to mammalian cells, have an obvious impact on aflatoxin production, which indicated that antimicrobial agents may be adopted as a new generation of potential agents for controlling aflatoxin contamination.
Collapse
Affiliation(s)
- Jing Li
- The Guangdong Provincial Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275, China
| | - Qing-Qing Zhi
- The Guangdong Provincial Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275, China
| | - Jie Zhang
- The Guangdong Provincial Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275, China
| | - Xiao-Yu Yuan
- The Guangdong Provincial Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275, China
| | - Li-Hong Jia
- The Guangdong Provincial Key Laboratory for Biotechnology Drug Candidates, School of Bioscience and Biopharmaceutics, Guangdong Pharmaceutical University, Guangzhou, 510006, China
| | - Yu-Lin Wan
- The Guangdong Provincial Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275, China
| | - Qiu-Yun Liu
- The Guangdong Provincial Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275, China.
| | - Jian-Rong Shi
- Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base, Ministry of Science and Technology, Nanjing, 210000, China.
| | - Zhu-Mei He
- The Guangdong Provincial Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275, China.
| |
Collapse
|
13
|
Katayama T, Bayram Ö, Mo T, Karahoda B, Valerius O, Takemoto D, Braus GH, Kitamoto K, Maruyama JI. Novel Fus3- and Ste12-interacting protein FsiA activates cell fusion-related genes in both Ste12-dependent and -independent manners in Ascomycete filamentous fungi. Mol Microbiol 2020; 115:723-738. [PMID: 33155715 DOI: 10.1111/mmi.14639] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 10/28/2020] [Accepted: 11/02/2020] [Indexed: 01/01/2023]
Abstract
Filamentous fungal cells, unlike yeasts, fuse during vegetative growth. The orthologs of mitogen-activated protein (MAP) kinase Fus3 and transcription factor Ste12 are commonly involved in the regulation of cell fusion. However, the specific regulatory mechanisms underlying cell fusion in filamentous fungi have not been revealed. In the present study, we identified the novel protein FsiA as an AoFus3- and AoSte12-interacting protein in the filamentous fungus Aspergillus oryzae. The expression of AonosA and cell fusion-related genes decreased upon fsiA deletion and increased with fsiA overexpression, indicating that FsiA is a positive regulator of cell fusion. In addition, the induction of cell fusion-related genes by fsiA overexpression was also observed in the Aoste12 deletion mutant, indicating that FsiA can induce the cell fusion-related genes in an AoSte12-independent manner. Surprisingly, the fsiA and Aoste12 double deletion mutant exhibited higher cell fusion efficiency and increased mRNA levels of the cell fusion-related genes as compared to the fsiA single deletion mutant, which revealed that AoSte12 represses the cell fusion-related genes in the fsiA deletion mutant. Taken together, our data demonstrate that FsiA activates the cell fusion-related genes by suppressing the negative function of AoSte12 as well as by an AoSte12-independent mechanism.
Collapse
Affiliation(s)
- Takuya Katayama
- Department of Biotechnology, The University of Tokyo, Tokyo, Japan.,Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo, Japan
| | - Özgür Bayram
- Biology Department, Maynooth University, Maynooth, Ireland
| | - Taoning Mo
- Department of Biotechnology, The University of Tokyo, Tokyo, Japan
| | - Betim Karahoda
- Biology Department, Maynooth University, Maynooth, Ireland
| | - Oliver Valerius
- Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, and Göttingen Center for Molecular Biosciences (GZMB), Georg-August University, Göttingen, Germany
| | - Daigo Takemoto
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Gerhard H Braus
- Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, and Göttingen Center for Molecular Biosciences (GZMB), Georg-August University, Göttingen, Germany
| | - Katsuhiko Kitamoto
- Pharmaceutical Medical Business Sciences, Nihon Pharmaceutical University, Tokyo, Japan
| | - Jun-Ichi Maruyama
- Department of Biotechnology, The University of Tokyo, Tokyo, Japan.,Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo, Japan
| |
Collapse
|
14
|
Frawley D, Greco C, Oakley B, Alhussain MM, Fleming AB, Keller NP, Bayram Ö. The tetrameric pheromone module SteC-MkkB-MpkB-SteD regulates asexual sporulation, sclerotia formation and aflatoxin production in Aspergillus flavus. Cell Microbiol 2020; 22:e13192. [PMID: 32068947 PMCID: PMC7202998 DOI: 10.1111/cmi.13192] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 01/07/2020] [Accepted: 01/26/2020] [Indexed: 11/29/2022]
Abstract
For eukaryotes like fungi to regulate biological responses to environmental stimuli, various signalling cascades are utilized, like the highly conserved mitogen‐activated protein kinase (MAPK) pathways. In the model fungus Aspergillus nidulans, a MAPK pathway known as the pheromone module regulates development and the production of secondary metabolites (SMs). This pathway consists five proteins, the three kinases SteC, MkkB and MpkB, the adaptor SteD and the scaffold HamE. In this study, homologs of these five pheromone module proteins have been identified in the plant and human pathogenic fungus Aspergillus flavus. We have shown that a tetrameric complex consisting of the three kinases and the SteD adaptor is assembled in this species. It was observed that this complex assembles in the cytoplasm and that MpkB translocates into the nucleus. Deletion of steC, mkkB, mpkB or steD results in abolishment of both asexual sporulation and sclerotia production. This complex is required for the positive regulation of aflatoxin production and negative regulation of various SMs, including leporin B and cyclopiazonic acid (CPA), likely via MpkB interactions in the nucleus. These data highlight the conservation of the pheromone module in Aspergillus species, signifying the importance of this pathway in regulating fungal development and secondary metabolism.
Collapse
Affiliation(s)
- Dean Frawley
- Department of Biology, Maynooth University, Maynooth, Co. Kildare, Ireland
| | - Claudio Greco
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Berl Oakley
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, USA
| | - Mohamed M Alhussain
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin, Ireland
| | - Alastair B Fleming
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin, Ireland
| | - Nancy P Keller
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, Wisconsin, USA.,Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Özgür Bayram
- Department of Biology, Maynooth University, Maynooth, Co. Kildare, Ireland
| |
Collapse
|
15
|
Zhi QQ, He L, Li JY, Li J, Wang ZL, He GY, He ZM. The Kinetochore Protein Spc105, a Novel Interaction Partner of LaeA, Regulates Development and Secondary Metabolism in Aspergillus flavus. Front Microbiol 2019; 10:1881. [PMID: 31456789 PMCID: PMC6700525 DOI: 10.3389/fmicb.2019.01881] [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: 04/01/2019] [Accepted: 07/30/2019] [Indexed: 01/04/2023] Open
Abstract
Nuclear protein LaeA is known as the global regulator of secondary metabolism in Aspergillus. LaeA connects with VeA and VelB to form a heterotrimeric complex, which coordinates fungal development and secondary metabolism. Here, we describe a new interaction partner of LaeA, the kinetochore protein Spc105, from the aflatoxin-producing fungus Aspergillus flavus. We showed that in addition to involvement in nuclear division, Spc105 is required for normal conidiophore development and sclerotia production of A. flavus. Moreover, Spc105 positively regulates the production of secondary metabolites such as aflatoxin and kojic acid, and negatively regulates the production of cyclopiazonic acid. Transcriptome analysis of the Δspc105 strain revealed that 23 backbone genes were differentially expressed, corresponding to 19 of the predicted 56 secondary metabolite gene clusters, suggesting a broad regulatory role of Spc105 in secondary metabolism. Notably, the reduced expression of laeA in our transcriptome data led to the discovery of the correlation between Spc105 and LaeA, and double mutant analysis indicated a functional interdependence between Spc105 and LaeA. Further, in vitro and in vivo protein interaction assays revealed that Spc105 interacts directly with the S-adenosylmethionine (SAM)-binding domain of LaeA, and that the leucine zipper motif in Spc105 is required for this interaction. The Spc105-LaeA interaction identified in our study indicates a cooperative interplay of distinct regulators in A. flavus, providing new insights into fungal secondary metabolism regulation networks.
Collapse
Affiliation(s)
- Qing-Qing Zhi
- The Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Lei He
- Cancer Hospital and Institute of Guangzhou Medical University, Guangzhou, China
| | - Jie-Ying Li
- The Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Jing Li
- The Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Zhen-Long Wang
- The Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Guang-Yao He
- The Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Zhu-Mei He
- The Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| |
Collapse
|
16
|
Fischer MS, Glass NL. Communicate and Fuse: How Filamentous Fungi Establish and Maintain an Interconnected Mycelial Network. Front Microbiol 2019; 10:619. [PMID: 31001214 PMCID: PMC6455062 DOI: 10.3389/fmicb.2019.00619] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 03/12/2019] [Indexed: 12/22/2022] Open
Abstract
Cell-to-cell communication and cell fusion are fundamental biological processes across the tree of life. Survival is often dependent upon being able to identify nearby individuals and respond appropriately. Communication between genetically different individuals allows for the identification of potential mating partners, symbionts, prey, or predators. In contrast, communication between genetically similar (or identical) individuals is important for mediating the development of multicellular organisms or for coordinating density-dependent behaviors (i.e., quorum sensing). This review describes the molecular and genetic mechanisms that mediate cell-to-cell communication and cell fusion between cells of Ascomycete filamentous fungi, with a focus on Neurospora crassa. Filamentous fungi exist as a multicellular, multinuclear network of hyphae, and communication-mediated cell fusion is an important aspect of colony development at each stage of the life cycle. Asexual spore germination occurs in a density-dependent manner. Germinated spores (germlings) avoid cells that are genetically different at specific loci, while chemotropically engaging with cells that share identity at these recognition loci. Germlings with genetic identity at recognition loci undergo cell fusion when in close proximity, a fitness attribute that contributes to more rapid colony establishment. Communication and cell fusion also occur between hyphae in a colony, which are important for reinforcing colony architecture and supporting the development of complex structures such as aerial hyphae and sexual reproductive structures. Over 70 genes have been identified in filamentous fungi (primarily N. crassa) that are involved in kind recognition, chemotropic interactions, and cell fusion. While the hypothetical signal(s) and receptor(s) remain to be described, a dynamic molecular signaling network that regulates cell-cell interactions has been revealed, including two conserved MAP-Kinase cascades, a conserved STRIPAK complex, transcription factors, a NOX complex involved in the generation of reactive oxygen species, cell-integrity sensors, actin, components of the secretory pathway, and several other proteins. Together these pathways facilitate the integration of extracellular signals, direct polarized growth, and initiate a transcriptional program that reinforces signaling and prepares cells for downstream processes, such as membrane merger, cell fusion and adaptation to heterokaryon formation.
Collapse
Affiliation(s)
- Monika S. Fischer
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley CA, United States
| | - N. Louise Glass
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley CA, United States
- Environmental Genomics and Systems Biology Division, The Lawrence Berkeley National Laboratory, Berkeley, CA, United States
| |
Collapse
|
17
|
Liu W, Cai Y, He P, Chen L, Bian Y. Comparative transcriptomics reveals potential genes involved in the vegetative growth of Morchella importuna. 3 Biotech 2019; 9:81. [PMID: 30800592 PMCID: PMC6374242 DOI: 10.1007/s13205-019-1614-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 02/02/2019] [Indexed: 12/16/2022] Open
Abstract
True morels (Morchella spp.) are edible, medicinal mushrooms which have recently been artificially cultivated in China but stable production remains a problem. Here, we describe complete and comprehensive transcriptome of Morchella importuna at the stages of vegetative mycelium (VM), initial sclerotium (IS) and mature sclerotium (MS) by deep transcriptional sequencing and de novo assembly for the first time and which will potentially provide useful information for improving its cultivation. A total of 26,496 genes were identified with a contig N50 length of 1763 bp and an average length of over 1064 bp. Additionally, 11,957 open reading frames (ORFs) were predicted and 9676 of them (80.9%) were annotated. The 2605 differentially expressed genes (DEGs) identified by gene expression clustering were mainly involved with energy metabolism and could be divided into three broad clusters, of which genes in cluster_1 and cluster_2 were involved in the metabolic process of carbohydrate, polysaccharide, hydrolase, caprolactam, beta-galactosidase, and disaccharide, respectively. Genes in cluster_3 were the largest category, mainly identified with the catalytic activity and transporter activity. Overall, the enzymes involved in the carbohydrate metabolism were highly expressed, and the CAZyme (carbohydrate-active enzyme) genes were significantly expressed within cluster_3. For expression verification, 16 CAZYme genes were selected for qRT-PCR, and the results suggested that the catabolism of carbohydrates occurs mainly in the vegetative mycelium stage, and the anabolism of the energy-rich substances is the main event of mycelial growth and sclerotial morphogenesis of M. importuna.
Collapse
Affiliation(s)
- Wei Liu
- Institute of Applied Mycology, Huazhong Agricultural University, 430070 Wuhan, China
- Key Laboratory of Agro-Microbial Resource Comprehensive Utilization, Ministry of Agriculture, Huazhong Agricultural University, 430070 Wuhan, Hubei China
| | - Yingli Cai
- Institute of Vegetable, Wuhan Academy of Agricultural Sciences, 430070 Wuhan, China
| | - Peixin He
- School of Food and Biological Engineering, Zhengzhou University of Light Industry, 450001 Zhengzhou, China
| | - Lianfu Chen
- Institute of Applied Mycology, Huazhong Agricultural University, 430070 Wuhan, China
- Key Laboratory of Agro-Microbial Resource Comprehensive Utilization, Ministry of Agriculture, Huazhong Agricultural University, 430070 Wuhan, Hubei China
| | - Yinbing Bian
- Institute of Applied Mycology, Huazhong Agricultural University, 430070 Wuhan, China
- Key Laboratory of Agro-Microbial Resource Comprehensive Utilization, Ministry of Agriculture, Huazhong Agricultural University, 430070 Wuhan, Hubei China
| |
Collapse
|
18
|
Cary JW, Entwistle S, Satterlee T, Mack BM, Gilbert MK, Chang PK, Scharfenstein L, Yin Y, Calvo AM. The Transcriptional Regulator Hbx1 Affects the Expression of Thousands of Genes in the Aflatoxin-Producing Fungus Aspergillus flavus. G3 (BETHESDA, MD.) 2019; 9:167-178. [PMID: 30425054 PMCID: PMC6325891 DOI: 10.1534/g3.118.200870] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 11/09/2018] [Indexed: 12/21/2022]
Abstract
In filamentous fungi, homeobox proteins are conserved transcriptional regulators described to control conidiogenesis and fruiting body formation. Eight homeobox (hbx) genes are found in the genome of the aflatoxin-producing ascomycete, Aspergillus flavus While loss-of-function of seven of the eight genes had little to no effect on fungal growth and development, disruption of hbx1, resulted in aconidial colonies and lack of sclerotial production. Furthermore, the hbx1 mutant was unable to produce aflatoxins B1 and B2, cyclopiazonic acid and aflatrem. In the present study, hbx1 transcriptome analysis revealed that hbx1 has a broad effect on A. flavus gene expression, and the effect of hbx1 increases overtime, impacting more than five thousand protein-coding genes. Among the affected genes, those in the category of secondary metabolism (SM), followed by that of cellular transport, were the most affected. Specifically, regarding the effect of hbx1 on SM, we found that genes in 44 SM gene clusters where upregulated while 49 were downregulated in the absence of hbx1, including genes in the SM clusters responsible for the synthesis of asparasone, piperazine and aflavarin, all known to be associated with sclerotia. In addition, our study revealed that hbx1 affects the expression of other transcription factor genes involved in development, including the conidiation central regulatory pathway and flb genes.
Collapse
Affiliation(s)
- Jeffrey W Cary
- Food and Feed Safety Research Unit, USDA/ARS, Southern Regional Research Center, New Orleans, Louisiana
| | - Sarah Entwistle
- Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois
| | - Timothy Satterlee
- Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois
| | - Brian M Mack
- Food and Feed Safety Research Unit, USDA/ARS, Southern Regional Research Center, New Orleans, Louisiana
| | - Matthew K Gilbert
- Food and Feed Safety Research Unit, USDA/ARS, Southern Regional Research Center, New Orleans, Louisiana
| | - Perng K Chang
- Food and Feed Safety Research Unit, USDA/ARS, Southern Regional Research Center, New Orleans, Louisiana
| | - Leslie Scharfenstein
- Food and Feed Safety Research Unit, USDA/ARS, Southern Regional Research Center, New Orleans, Louisiana
| | - Yanbin Yin
- Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois
| | - Ana M Calvo
- Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois
| |
Collapse
|
19
|
Pfannenstiel BT, Greco C, Sukowaty AT, Keller NP. The epigenetic reader SntB regulates secondary metabolism, development and global histone modifications in Aspergillus flavus. Fungal Genet Biol 2018; 120:9-18. [PMID: 30130575 PMCID: PMC6215504 DOI: 10.1016/j.fgb.2018.08.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 08/13/2018] [Accepted: 08/17/2018] [Indexed: 12/22/2022]
Abstract
Due to the role, both beneficial and harmful, that fungal secondary metabolites play in society, the study of their regulation is of great importance. Genes for any one secondary metabolite are contiguously arranged in a biosynthetic gene cluster (BGC) and subject to regulation through the remodeling of chromatin. Histone modifying enzymes can place or remove post translational modifications (PTM) on histone tails which influences how tight or relaxed the chromatin is, impacting transcription of BGCs. In a recent forward genetic screen, the epigenetic reader SntB was identified as a transcriptional regulator of the sterigmatocystin BGC in A. nidulans, and regulated the related metabolite aflatoxin in A. flavus. In this study we investigate the role of SntB in the plant pathogen A. flavus by analyzing both ΔsntB and overexpression sntB genetic mutants. Deletion of sntB increased global levels of H3K9K14 acetylation and impaired several developmental processes including sclerotia formation, heterokaryon compatibility, secondary metabolite synthesis, and ability to colonize host seeds; in contrast the overexpression strain displayed fewer phenotypes. ΔsntB developmental phenotypes were linked with SntB regulation of NosA, a transcription factor regulating the A. flavus cell fusion cascade.
Collapse
Affiliation(s)
| | - Claudio Greco
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI, USA
| | - Andrew T Sukowaty
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI, USA
| | - Nancy P Keller
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI, USA; Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, USA.
| |
Collapse
|
20
|
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.
Collapse
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
| |
Collapse
|
21
|
Zhao X, Zhi QQ, Li JY, Keller NP, He ZM. The Antioxidant Gallic Acid Inhibits Aflatoxin Formation in Aspergillus flavus by Modulating Transcription Factors FarB and CreA. Toxins (Basel) 2018; 10:toxins10070270. [PMID: 29970790 PMCID: PMC6071284 DOI: 10.3390/toxins10070270] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 06/23/2018] [Accepted: 06/27/2018] [Indexed: 12/28/2022] Open
Abstract
Aflatoxin biosynthesis is correlated with oxidative stress and is proposed to function as a secondary defense mechanism to redundant intracellular reactive oxygen species (ROS). We find that the antioxidant gallic acid inhibits aflatoxin formation and growth in Aspergillus flavus in a dose-dependent manner. Global expression analysis (RNA-Seq) of gallic acid-treated A. flavus showed that 0.8% (w/v) gallic acid revealed two possible routes of aflatoxin inhibition. Gallic acid significantly inhibited the expression of farB, encoding a transcription factor that participates in peroxisomal fatty acid β-oxidation, a fundamental contributor to aflatoxin production. Secondly, the carbon repression regulator encoding gene, creA, was significantly down regulated by gallic acid treatment. CreA is necessary for aflatoxin synthesis, and aflatoxin biosynthesis genes were significantly downregulated in ∆creA mutants. In addition, the results of antioxidant enzyme activities and the lipid oxidation levels coupled with RNA-Seq data of antioxidant genes indicated that gallic acid may reduce oxidative stress through the glutathione- and thioredoxin-dependent systems in A. flavus.
Collapse
Affiliation(s)
- Xixi Zhao
- The Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Science, Sun Yat-sen University, Guangzhou 510275, China.
| | - Qing-Qing Zhi
- The Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Science, Sun Yat-sen University, Guangzhou 510275, China.
| | - Jie-Ying Li
- The Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Science, Sun Yat-sen University, Guangzhou 510275, China.
| | - Nancy P Keller
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI 53706, USA.
| | - Zhu-Mei He
- The Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Science, Sun Yat-sen University, Guangzhou 510275, China.
| |
Collapse
|
22
|
Larrondo LF, Canessa P. The Clock Keeps on Ticking: Emerging Roles for Circadian Regulation in the Control of Fungal Physiology and Pathogenesis. Curr Top Microbiol Immunol 2018; 422:121-156. [PMID: 30255278 DOI: 10.1007/82_2018_143] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Tic-tac, tic-tac, the sound of time is familiar to us, yet, it also silently shapes daily biological processes conferring 24-hour rhythms in, among others, cellular and systemic signaling, gene expression, and metabolism. Indeed, circadian clocks are molecular machines that permit temporal control of a variety of processes in individuals, with a close to 24-hour period, optimizing cellular dynamics in synchrony with daily environmental cycles. For over three decades, the molecular bases of these clocks have been extensively described in the filamentous fungus Neurospora crassa, yet, there have been few molecular studies in fungi other than Neurospora, despite evidence of rhythmic phenomena in many fungal species, including pathogenic ones. This chapter will revise the mechanisms underlying clock regulation in the model fungus N. crassa, as well as recent findings obtained in several fungi. In particular, this chapter will review the effect of circadian regulation of virulence and organismal interactions, focusing on the phytopathogen Botrytis cinerea, as well as several entomopathogenic fungi, including the behavior-manipulating species Ophiocordyceps kimflemingiae and Entomophthora muscae. Finally, this review will comment current efforts in the study of mammalian pathogenic fungi, while highlighting recent circadian lessons from parasites such as Trypanosoma and Plasmodium. The clock keeps on ticking, whether we can hear it or not.
Collapse
Affiliation(s)
- Luis F Larrondo
- Millennium Institute for Integrative Biology (iBio), Santiago, Chile. .,Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.
| | - Paulo Canessa
- Millennium Institute for Integrative Biology (iBio), Santiago, Chile.,Facultad de Ciencias de la Vida, Centro de Biotecnologia Vegetal, Universidad Andres Bello, Santiago, Chile
| |
Collapse
|