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Li F, Zhang J, Zhong H, Yu K, Chen J. Comprehensive Insights into the Remarkable Function and Regulatory Mechanism of FluG during Asexual Development in Beauveria bassiana. Int J Mol Sci 2024; 25:6261. [PMID: 38892450 PMCID: PMC11173134 DOI: 10.3390/ijms25116261] [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: 04/29/2024] [Revised: 05/24/2024] [Accepted: 05/31/2024] [Indexed: 06/21/2024] Open
Abstract
Asexual development is the main propagation and transmission mode of Beauveria bassiana and the basis of its pathogenicity. The regulation mechanism of conidiation and the key gene resources for utilization are key links to improving the conidia yield and quality of Beauveria bassiana. Their clarification may promote the industrialization of fungal pesticides. Here, we compared the regulation of morphology, resistance to external stress, virulence, and nutrient utilization capacity between the upstream developmental regulatory gene fluG and the key genes brlA, abaA, and wetA in the central growth and development pathway. The results showed that the ΔbrlA and ΔabaA mutants completely lost the capacity to conidiate and that the ΔwetA mutant had seriously reduced conidiation capacity. Although the deletion of fluG did not reduce the conidiation ability as much as deletions of brlA, abaA, and wetA, it significantly reduced the fungal response to external stress, virulence, and nutrient utilization, while the deletion of the three other genes had little effect. Via transcriptome analysis and screening the yeast nuclear system library, we found that the differentially expressed genes in the ΔfluG mutants were concentrated in the signaling pathways of ABC transporters, propionate metabolism, tryptophan metabolism, DNA replication, mismatch repair, and fatty acid metabolism. FluG directly acted on 40 proteins that were involved in various signaling pathways such as metabolism, oxidative stress, and cell homeostasis. The analysis indicated that the regulatory function of fluG was mainly involved in DNA replication, cell homeostasis, fungal growth and metabolism, and the response to external stress. Our results revealed the biological function of fluG in asexual development and the responses to several environmental stresses as well as its influence on the asexual development regulatory network in B. bassiana.
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Affiliation(s)
| | - Juefeng Zhang
- Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China; (F.L.); (H.Z.); (K.Y.)
| | | | | | - Jianming Chen
- Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China; (F.L.); (H.Z.); (K.Y.)
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2
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Chen X, Moran Torres JP, Wösten HAB. The role of the Flb protein family in the life cycle of Aspergillus niger. Antonie Van Leeuwenhoek 2024; 117:58. [PMID: 38502333 PMCID: PMC10950988 DOI: 10.1007/s10482-024-01957-x] [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: 01/16/2024] [Accepted: 03/04/2024] [Indexed: 03/21/2024]
Abstract
Genes flbA-E are involved in sporulation and vegetative growth in Aspergillus nidulans. Inactivation of either of these genes results in a fluffy phenotype with delayed or even abolished sporulation. Previously, a non-sporulating phenotype was obtained by inactivating flbA in Aspergillus niger, which was accompanied by lysis, thinner cell walls, and an increased secretome complexity. Here, we further studied the role of the flb genes of A. niger. Strains ΔflbA, ΔflbB and ΔflbE showed increased biomass formation, while inactivation of flbA-D reduced, or even abolished, formation of conidia. Strain ΔflbA was more sensitive to H2O2, DTT, and the cell wall integrity stress compounds SDS and Congo Red (CR). Also, ΔflbC was more sensitive to SDS, while ΔflbB, ΔflbD, and ΔflbE were more sensitive to CR. On the other hand, inactivation of flbE increased resistance to H2O2. Enzyme secretion was impacted when the Δflb strains were grown on xylose. Strain ΔflbE showed reduced xylanase, cellulase and amylase secretion. On the other hand, amylase secretion at the periphery of the ΔflbA colony was reduced but not in its center, while secretion of this enzyme was increased in the center of the ΔflbB colony but not at its periphery. Inactivation of flbC and flbD also impacted zonal cellulase and amylase activity. Together, the Flb protein family of A. niger function in biomass formation, sporulation, stress response, and protein secretion.
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Affiliation(s)
- Xiaoyi Chen
- Microbiology, Department of Biology, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Juan P Moran Torres
- Microbiology, Department of Biology, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Han A B Wösten
- Microbiology, Department of Biology, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands.
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Son YE, Han J, Lee KT, Park HS. Pleiotropic functions of SscA on the asexual spore of the human pathogenic fungus Aspergillus fumigatus. Mycology 2023; 15:238-254. [PMID: 38813476 PMCID: PMC11132850 DOI: 10.1080/21501203.2023.2294061] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Accepted: 12/06/2023] [Indexed: 05/31/2024] Open
Abstract
Asexual spores, called conidia, are key reproductive fungal particles that enable survival in harsh environmental conditions or host systems. The conidia can infect humans, animals, and plants to cause various fungal diseases. Transcription factors, including VosA, WetA, and SscA, have key roles in conidia formation and long-term survival in Aspergillus nidulans. Herein, we report the pleiotropic functions of SscA in the conidia of the human pathogen A. fumigatus. The deletion of sscA increased conidia formation despite decreased fungal growth. Absence of sscA impaired long-term survival and reduced spore resistance to various stresses, including heat, UV, and oxidation. Transcriptomic analyses showed that SscA involved the mRNA expression of cell wall organisation-related genes. Importantly, the sscA deletion mutant conidia contained an increased amount of β-glucan and chitin compared to wild type conidia. In addition, conidial gliotoxin production was decreased in the sscA deletion strain. Overall, SscA has pleiotropic roles in conidia formation, maturation and dormancy and mycotoxin production in A. fumigatus.
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Affiliation(s)
- Ye-Eun Son
- School of Food Science and Biotechnology, Kyungpook National University, Daegu, Republic of Korea
| | - Jiwoo Han
- Korea Zoonosis Research Institute, Jeonbuk National University, Iksan, Republic of Korea
| | - Kyung-Tae Lee
- Korea Zoonosis Research Institute, Jeonbuk National University, Iksan, Republic of Korea
| | - Hee-Soo Park
- School of Food Science and Biotechnology, Kyungpook National University, Daegu, Republic of Korea
- Department of Integrative Biology, Kyungpook National University, Daegu, Republic of Korea
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4
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Tian J, Pu M, Chen B, Wang G, Li C, Zhang X, Yu Y, Wang Z, Kong Z. Verticillium dahliae Asp1 regulates the transition from vegetative growth to asexual reproduction by modulating microtubule dynamic organization. Environ Microbiol 2023; 25:738-750. [PMID: 36537236 DOI: 10.1111/1462-2920.16320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 12/16/2022] [Indexed: 12/24/2022]
Abstract
Verticillium dahliae is a devastating pathogenic fungus that causes severe vascular wilts in more than 400 dicotyledonous plants. The conidiation of V. dahliae in plant vascular tissues is the key strategy for its adaptation to the nutrient-poor environment and is required for its pathogenicity. However, it remains unclear about the regulatory mechanism of conidium production of V. dahliae in vascular tissues. Here, we found that VdAsp1, encoding an inositol polyphosphate kinase, is indispensable for the pathogenicity of V. dahliae. Loss of VdAsp1 function does not affect the invasion of the host, but it impairs the colonization and proliferation in vascular tissues. The ΔVdAsp1 mutant shows defective initiation of conidiophore formation and reduced expression of genes associated with the central developmental pathway. By live-cell imaging, we observed that some of ΔVdAsp1 mutant hyphae are swollen, and microtubule arrangements at the apical region of these hyphae are disorganized. These results indicate that VdAsp1 regulates the transition from vegetative growth to asexual reproduction by modulating microtubule dynamic organization, which is essential for V. dahliae to colonize and proliferate in vascular tissues. These findings provided a potential new direction in the control of vascular wilt pathogen by targeting conidium production in vascular tissues.
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Affiliation(s)
- Juan Tian
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Mengli Pu
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, School of Agricultural Sciences, Zhengzhou University, Zhengzhou, China
| | - Bin Chen
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Guangda Wang
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Chunli Li
- Public Technology Service Center, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Xiaxia Zhang
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Yanjun Yu
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Zhi Wang
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, School of Agricultural Sciences, Zhengzhou University, Zhengzhou, China
| | - Zhaosheng Kong
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- Shanxi Key Laboratory of Minor Crops Germplasm Innovation and Molecular Breeding, Academy of Agronomy, Shanxi Agricultural University, Taiyuan, China
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5
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Jia L, Huang Y, Yu JH, Stadler M, Shao Y, Chen W, Chen F. Characterization of key upstream asexual developmental regulators in Monascus ruber M7. FOOD BIOSCI 2022. [DOI: 10.1016/j.fbio.2022.102153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Roles of BrlA and AbaA in Mediating Asexual and Insect Pathogenic Lifecycles of Metarhizium robertsii. J Fungi (Basel) 2022; 8:jof8101110. [PMID: 36294676 PMCID: PMC9604561 DOI: 10.3390/jof8101110] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 10/19/2022] [Accepted: 10/19/2022] [Indexed: 11/07/2022] Open
Abstract
BrlA and AbaA are key activators of the central developmental pathway (CDP) that controls asexual development in Aspergillus but their roles remain insufficiently understood in hypocerealean insect pathogens. Here, regulatory roles of BrlA and AbaA orthologs in Metarhizium robertsii (Clavicipitaceae) were characterized for comparison to those elucidated previously in Beauveria bassiana (Cordycipitaceae) at phenotypic and transcriptomic levels. Time-course transcription profiles of brlA, abaA, and the other CDP activator gene wetA revealed that they were not so sequentially activated in M. robertsii as learned in Aspergillus. Aerial conidiation essential for fungal infection and dispersal, submerged blastospore production mimicking yeast-like budding proliferation in insect hemocoel, and insect pathogenicity via cuticular penetration were all abolished as a consequence of brlA or abaA disruption, which had little impact on normal hyphal growth. The disruptants were severely compromised in virulence via cuticle-bypassing infection (intrahemocoel injection) and differentially impaired in cellular tolerance to oxidative and cell wall-perturbing stresses. The ΔbrlA and ΔabaA mutant shad 255 and 233 dysregulated genes (up/down ratios: 52:203 and 101:122) respectively, including 108 genes co-dysregulated. These counts were small compared with 1513 and 2869 dysregulated genes (up/down ratios: 707:806 and 1513:1356) identified in ΔbrlA and ΔabaA mutants of B. bassiana. Results revealed not only conserved roles for BrlA and AbaA in asexual developmental control but also their indispensable roles in fungal adaptation to the insect-pathogenic lifecycle and host habitats. Intriguingly, BrlA- or AbaA-controlled gene expression networks are largely different between the two insect pathogens, in which similar phenotypes were compromised in the absence of either brlA or abaA.
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Cho HJ, Son SH, Chen W, Son YE, Lee I, Yu JH, Park HS. Regulation of Conidiogenesis in Aspergillus flavus. Cells 2022; 11:cells11182796. [PMID: 36139369 PMCID: PMC9497164 DOI: 10.3390/cells11182796] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 08/29/2022] [Accepted: 09/06/2022] [Indexed: 11/16/2022] Open
Abstract
Aspergillus flavus is a representative fungal species in the Aspergillus section Flavi and has been used as a model system to gain insights into fungal development and toxin production. A. flavus has several adverse effects on humans, including the production of the most carcinogenic mycotoxin aflatoxins and causing aspergillosis in immune-compromised patients. In addition, A. flavus infection of crops results in economic losses due to yield loss and aflatoxin contamination. A. flavus is a saprophytic fungus that disperses in the ecosystem mainly by producing asexual spores (conidia), which also provide long-term survival in the harsh environmental conditions. Conidia are composed of the rodlet layer, cell wall, and melanin and are produced from an asexual specialized structure called the conidiophore. The production of conidiophores is tightly regulated by various regulators, including the central regulatory cascade composed of BrlA-AbaA-WetA, the fungi-specific velvet regulators, upstream regulators, and developmental repressors. In this review, we summarize the findings of a series of recent studies related to asexual development in A. flavus and provide insights for a better understanding of other fungal species in the section Flavi.
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Affiliation(s)
- He-Jin Cho
- School of Food Science and Biotechnology, Kyungpook National University, Daegu 41566, Korea
| | - Sung-Hun Son
- School of Food Science and Biotechnology, Kyungpook National University, Daegu 41566, Korea
| | - Wanping Chen
- Department of Molecular Microbiology and Genetics, University of Göttingen, 37077 Göttingen, Germany
| | - Ye-Eun Son
- School of Food Science and Biotechnology, Kyungpook National University, Daegu 41566, Korea
| | - Inhyung Lee
- Department of Bio and Fermentation Convergence Technology, Kookmin University, Seoul 02707, Korea
| | - Jae-Hyuk Yu
- Department of Bacteriology, University of Wisconsin, Madison, WI 53706, USA
- Department of Systems Biotechnology, Konkuk University, Seoul 05029, Korea
| | - Hee-Soo Park
- School of Food Science and Biotechnology, Kyungpook National University, Daegu 41566, Korea
- Department of Integrative Biology, Kyungpook National University, Daegu 41566, Korea
- Correspondence: ; Tel.: +82-53-950-5751
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Luo X, Zhan X, Ruan R, Xi Y, Shen C, Wang H, Wang M. Genome-wide identification of the Penicillium digitatum bZIP gene family and the roles of one key member, PdatfA. Res Microbiol 2022; 173:103970. [PMID: 35868518 DOI: 10.1016/j.resmic.2022.103970] [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: 03/16/2022] [Revised: 07/03/2022] [Accepted: 07/08/2022] [Indexed: 11/16/2022]
Abstract
Penicillium digitatum is the most common cause of postharvest decay in citrus fruits around the world. Previous studies revealed that the bZIP gene family plays crucial roles in development, stress adaptation, and pathogenicity in fungi. However, little is known about the bZIP genes in P. digitatum. In this study, we systematically identified the bZIP family in 23 Penicillium species and analyzed their evolutionary relationships. We found that gene loss and gene duplication shaped the evolution of the Penicillium bZIP family. P. digitatum experienced 3 bZIP gene loss events, but with no gene duplication. We subsequently characterized the biological functions of one important member, PdatfA in P. digitatum by constructing the deletion mutant. Results showed that ΔPdatfA exhibited a moderate growth defect, reduced pigmentation, and slightly increased resistance to fungicides iprodione and fludioxonil. However, ΔPdatfA displayed similar rot symptoms to that of the wild type. The ΔPdatfA mycelia were not affected in response to oxidative stress while its conidia showed enhanced resistance due to the upregulation of catalases. Our results provide new insights into the evolution and functions of the bZIP gene family in Penicillium.
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Affiliation(s)
- Xiujun Luo
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China
| | - Xiaori Zhan
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China
| | - Ruoxin Ruan
- Hangzhou Academy of Agricultural Sciences, Hangzhou 310024, China
| | - Yue Xi
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China
| | - Chenjia Shen
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China
| | - Huizhong Wang
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China
| | - Mingshuang Wang
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China.
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FluG and FluG-like FlrA Coregulate Manifold Gene Sets Vital for Fungal Insect-Pathogenic Lifestyle but Not Involved in Asexual Development. mSystems 2022; 7:e0031822. [PMID: 35862810 PMCID: PMC9426541 DOI: 10.1128/msystems.00318-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The central developmental pathway (CDP) activator gene brlA is activated by the upstream genes fluG and flbA–flbE in Aspergillus nidulans. Increasing evidences of fungal genome divergence make it necessary to clarify whether such genetic principles fit Pezizomycotina. Previously, fluG disruption resulted in limited conidiation defect and little effect on the expression of brlA and flbA–flbE in Beauveria bassiana possessing the other FluG-like regulator FlrA. Here, single-disruption (SD) mutants of flrA and double-disruption (DD) mutants of flrA and fluG were analyzed to clarify whether FlrA and FluG are upstream regulators of key CDP genes. Despite similar subcellular localization, no protein-protein interaction was detected between FlrA and FluG, suggesting mutual independence. Three flrA SD mutants showed phenotypes similar to those previously described for ΔfluG, including limited conidiation defect, facilitated blastospore production, impaired spore quality, blocked host infection, delayed proliferation in vivo, attenuated virulence, and increased sensitivities to multiple stresses. Three DD mutants resembled the SD mutants in all phenotypes except more compromised pathogenicity and tolerance to heat shock- or calcofluor white-induced stress. No CDP gene appeared in 1,622 and 2,234 genes dysregulated in the ΔflrA and ΔfluG mutants, respectively. The majority (up/down ratio: 540:875) of those dysregulated genes were co-upregulated or co-downregulated at similar levels in the two mutants. These findings unravel novel roles for flrA and fluG in coregulating manifold gene sets vital for fungal adaptation to insect-pathogenic lifestyle and environment but not involved in CDP activation. IMPORTANCE FluG is a core regulator upstream of central developmental pathway (CDP) in Aspergillus nidulans but multiple FluG-like regulators (FLRs) remain functionally uncharacterized in ascomycetes. Our previous study revealed no role for FluG in the CDP activation and an existence of sole FLR (FlrA) in an insect-pathogenic fungus. This study reveals a similarity of FlrA to FluG in domain architecture and subcellular localization. Experimental data from analyses of targeted single- and double-gene knockout mutants demonstrate similar roles of FrlA and FluG in stress tolerance and infection cycle but no role of either in CDP activation. Transcriptomic analyses reveal that FlrA and FluG coregulate a large number of same genes at similar levels. However, the regulated genes include no key CDP gene. These findings uncover that FlrA and FluG play similar roles in the fungal adaptation to insect-pathogenic lifestyle and environment but no role in the activation of CDP.
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Li L, Zhu XM, Zhang YR, Cai YY, Wang JY, Liu MY, Wang JY, Bao JD, Lin FC. Research on the Molecular Interaction Mechanism between Plants and Pathogenic Fungi. Int J Mol Sci 2022; 23:ijms23094658. [PMID: 35563048 PMCID: PMC9104627 DOI: 10.3390/ijms23094658] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 04/07/2022] [Accepted: 04/21/2022] [Indexed: 02/01/2023] Open
Abstract
Plant diseases caused by fungi are one of the major threats to global food security and understanding the interactions between fungi and plants is of great significance for plant disease control. The interaction between pathogenic fungi and plants is a complex process. From the perspective of pathogenic fungi, pathogenic fungi are involved in the regulation of pathogenicity by surface signal recognition proteins, MAPK signaling pathways, transcription factors, and pathogenic factors in the process of infecting plants. From the perspective of plant immunity, the signal pathway of immune response, the signal transduction pathway that induces plant immunity, and the function of plant cytoskeleton are the keys to studying plant resistance. In this review, we summarize the current research progress of fungi–plant interactions from multiple aspects and discuss the prospects and challenges of phytopathogenic fungi and their host interactions.
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Affiliation(s)
- Lin Li
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-Products, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China; (L.L.); (X.-M.Z.); (J.-Y.W.); (J.-D.B.)
| | - Xue-Ming Zhu
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-Products, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China; (L.L.); (X.-M.Z.); (J.-Y.W.); (J.-D.B.)
| | - Yun-Ran Zhang
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-Products, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China; (Y.-R.Z.); (Y.-Y.C.); (J.-Y.W.); (M.-Y.L.)
| | - Ying-Ying Cai
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-Products, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China; (Y.-R.Z.); (Y.-Y.C.); (J.-Y.W.); (M.-Y.L.)
| | - Jing-Yi Wang
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-Products, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China; (Y.-R.Z.); (Y.-Y.C.); (J.-Y.W.); (M.-Y.L.)
| | - Meng-Yu Liu
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-Products, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China; (Y.-R.Z.); (Y.-Y.C.); (J.-Y.W.); (M.-Y.L.)
| | - Jiao-Yu Wang
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-Products, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China; (L.L.); (X.-M.Z.); (J.-Y.W.); (J.-D.B.)
| | - Jian-Dong Bao
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-Products, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China; (L.L.); (X.-M.Z.); (J.-Y.W.); (J.-D.B.)
| | - Fu-Cheng Lin
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-Products, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China; (L.L.); (X.-M.Z.); (J.-Y.W.); (J.-D.B.)
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-Products, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China; (Y.-R.Z.); (Y.-Y.C.); (J.-Y.W.); (M.-Y.L.)
- Correspondence: ; Tel.: +86-571-88404007
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Systematic Characterization of bZIP Transcription Factors Required for Development and Aflatoxin Generation by High-Throughput Gene Knockout in Aspergillus flavus. J Fungi (Basel) 2022; 8:jof8040356. [PMID: 35448587 PMCID: PMC9031554 DOI: 10.3390/jof8040356] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 03/23/2022] [Accepted: 03/23/2022] [Indexed: 12/31/2022] Open
Abstract
The basic leucine zipper (bZIP) is an important transcription factor required for fungal development, nutrient utilization, biosynthesis of secondary metabolites, and defense against various stresses. Aspergillus flavus is a major producer of aflatoxin and an opportunistic fungus on a wide range of hosts. However, little is known about the role of most bZIP genes in A. flavus. In this study, we developed a high-throughput gene knockout method based on an Agrobacterium-mediated transformation system. Gene knockout construction by yeast recombinational cloning and screening of the null mutants by double fluorescence provides an efficient way to construct gene-deleted mutants for this multinucleate fungus. We deleted 15 bZIP genes in A. flavus. Twelve of these genes were identified and characterized in this strain for the first time. The phenotypic analysis of these mutants showed that the 15 bZIP genes play a diverse role in mycelial growth (eight genes), conidiation (13 genes), aflatoxin biosynthesis (10 genes), oxidative stress response (11 genes), cell wall stress (five genes), osmotic stress (three genes), acid and alkali stress (four genes), and virulence to kernels (nine genes). Impressively, all 15 genes were involved in the development of sclerotia, and the respective deletion mutants of five of them did not produce sclerotia. Moreover, MetR was involved in this biological process. In addition, HapX and MetR play important roles in the adaptation to excessive iron and sulfur metabolism, respectively. These studies provide comprehensive insights into the role of bZIP transcription factors in this aflatoxigenic fungus of global significance.
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12
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Genome-Wide Identification and Expression Analysis of the Basic Leucine Zipper (bZIP) Transcription Factor Gene Family in Fusarium graminearum. Genes (Basel) 2022; 13:genes13040607. [PMID: 35456413 PMCID: PMC9028111 DOI: 10.3390/genes13040607] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 03/18/2022] [Accepted: 03/26/2022] [Indexed: 12/14/2022] Open
Abstract
The basic leucine zipper (bZIP) is a widely found transcription factor family that plays regulatory roles in a variety of cellular processes including cell growth and development and various stress responses. However, the bZIP gene family has not been well studied at a genome-wide scale in Fusarium graminearum (Fg), a potent pathogen of cereal grains. In the present study, we conducted a genome-wide identification, characterization, and expression profiling of 22 F. graminearum bZIP (FgbZIP) genes at different developmental stages and under various abiotic stresses. All identified FgbZIPs were categorized into nine groups based on their sequence similarity and phylogenetic tree analysis. Furthermore, the gene structure analysis, conserved motif analysis, chromosomal localization, protein network studies, and synteny analysis were performed. The symmetry of the exon and intron varied with the phylogenetic groups. The post-translational modifications (PTMs) analysis also predicted several phosphorylation sites in FgbZIPs, indicating their functional diversity in cellular processes. The evolutionary study identified many orthogroups among eight species and also predicted several gene duplication events in F. graminearum. The protein modeling indicated the presence of a higher number of α-helices and random coils in their structures. The expression patterns of FgbZIP genes showed that 5 FgbZIP genes, including FgbZIP_1.1, FgbZIP_1.3, FgbZIP_2.6 FgbZIP_3.1 and FgbZIP_4.3, had high expression at different growth and conidiogenesis stages. Similarly, eight genes including FgbZIP_1.1, FgbZIP_1.6, FgbZIP_2.3, FgbZIP_2.4, FgbZIP_4.1, FgbZIP_4.2, FgbZIP_4.3 and FgbZIP_4.6 demonstrated their putative role in response to various abiotic stresses. In summary, these results provided basic information regarding FgbZIPs which are helpful for further functional analysis.
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Differential Roles of Five Fluffy Genes (flbA–flbE) in the Lifecycle In Vitro and In Vivo of the Insect–Pathogenic Fungus Beauveria bassiana. J Fungi (Basel) 2022; 8:jof8040334. [PMID: 35448565 PMCID: PMC9031332 DOI: 10.3390/jof8040334] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 03/18/2022] [Accepted: 03/21/2022] [Indexed: 01/06/2023] Open
Abstract
The fluffy genes flbA–flbE are well-known players in the upstream developmental activation pathway that activates the key gene brlA of central developmental pathway (CDP) to initiate conidiation in Aspergillus nidulans. Here, we report insignificant roles of their orthologs in radial growth of Beauveria bassiana under normal culture conditions and different stresses although flbA and flbD were involved in respective responses to heat shock and H2O2. Aerial conidiation level was lowered in the deletion mutants of flbB and flbE (~15%) less than of flbA and flbC (~30%), in which the key CDP genes brlA and abaA were repressed consistently during normal incubation. The CDP-controlled blastospore production in submerged cultures mimicking insect hemolymph was abolished in the flbA mutant with brlA and abaA being sharply repressed, and decreased by 55% in the flbC mutant with only abaA being downregulated. The fungal virulence against a model insect was attenuated in the absence of flbA more than of flbC irrespective of normal cuticle infection or cuticle-bypassing infection (intrahemocoel injection). These findings unravel more important role of flbA than of flbC, but null roles of flbB/D/E, in B. bassiana’s insect–pathogenic lifecycle and a scenario distinctive from that in A.nidulans.
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Magnaporthe oryzae Transcription Factor MoBZIP3 Regulates Appressorium Turgor Pressure Formation during Pathogenesis. Int J Mol Sci 2022; 23:ijms23020881. [PMID: 35055065 PMCID: PMC8778449 DOI: 10.3390/ijms23020881] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 01/10/2022] [Accepted: 01/12/2022] [Indexed: 02/01/2023] Open
Abstract
The devastating fungus Magnaporthe oryzae (M. oryzae) forms a specialized infection structure known as appressorium, which generates enormous turgor, to penetrate the plant cells. However, how M. oryzae regulates the appressorium turgor formation, is not well understood. In this study, we identified MoBZIP3, a bZIP transcription factor that functioned in pathogenesis in M. oryzae. We found that the pathogenicity of the MoBZIP3 knockout strain (Δmobzip3) was significantly reduced, and the defect was restored after re-expression of MoBZIP3, indicating that MoBZIP3 is required for M. oryzae virulence. Further analysis showed that MoBZIP3 functions in utilization of glycogen and lipid droplets for generation of glycerol in appressorium. MoBZIP3 localized in the nucleus and could bind directly to the promoters of the glycerol synthesis-related genes, MoPTH2, MoTGL1 and MoPEX6, and regulate their expression which is critical for glycerol synthesis in the appressorium turgor pressure generation. Furthermore, the critical turgor sensor gene MoSln1 was also down regulated and its subcellular localization was aberrant in Δmobzip3, which leads to a disordered actin assembly in the Δmobzip3 appressorium. Taken together, these results revealed new regulatory functions of the bZIP transcription factor MoBZIP3, in regulating M. oryzae appressorium turgor formation and infection.
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Song M, Fang S, Li Z, Wang N, Li X, Liu W, Zhang Y, Lin C, Miao W. CsAtf1, a bZIP transcription factor, is involved in fludioxonil sensitivity and virulence in the rubber tree anthracnose fungus Colletotrichum siamense. Fungal Genet Biol 2021; 158:103649. [PMID: 34921997 DOI: 10.1016/j.fgb.2021.103649] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 11/16/2021] [Accepted: 11/27/2021] [Indexed: 11/29/2022]
Abstract
In phytopathogenic fungi, the HOG MAPK pathway has roles in osmoregulation, fungicide sensitivity, and other processes. The ATF1/CREB-activating transcription factor Atf1 is a regulator that functions downstream of the HOG MAPK pathway. Here, we identified a gene, designated CsAtf1, that encodes a bZIP transcription factor in Colletotrichum siamense, which is the main pathogen that causes Colletotrichum leaf fall disease in rubber trees in China. CsAtf1 localizes to the nucleus. Its mRNA expression correlates positively with that of CsPbs2 and CsHog1 in the HOG MAPK pathway in response to activator (anisomycin), inhibitor (SB203580) and fludioxonil treatments. The CsAtf1 deletion mutant showed slightly retarded mycelial growth, small conidia, slow spore germination, and abnormal appressorium formation. This mutant showed the increased spore germination rate after fludioxonil treatment and more resistance to the fungicide fludioxonil than did the wild-type fungus. However, unlike deletion of Pbs2 or Hog1, which resulted in greater sensitivity to osmotic stress, the CsAtf1 deletion induced slightly increased resistance to osmotic stress and the cell wall stress response. The ΔCsAtf1 strain also exhibited significantly reduced virulence on rubber tree leaves. These data revealed that CsAtf1 plays a key role in the regulation of fludioxonil sensitivity and in pathogenicity regulation in C. siamense.
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Affiliation(s)
- Miao Song
- College of Plant Protection/Key Laboratory of Green Prevention and Control of Tropical Plant Diseases and Pests, Ministry of Education, Hainan University, Haikou 570228, China
| | - Siqi Fang
- College of Plant Protection/Key Laboratory of Green Prevention and Control of Tropical Plant Diseases and Pests, Ministry of Education, Hainan University, Haikou 570228, China
| | - Zhigang Li
- College of Plant Protection/Key Laboratory of Green Prevention and Control of Tropical Plant Diseases and Pests, Ministry of Education, Hainan University, Haikou 570228, China
| | - Na Wang
- College of Plant Protection/Key Laboratory of Green Prevention and Control of Tropical Plant Diseases and Pests, Ministry of Education, Hainan University, Haikou 570228, China
| | - Xiao Li
- College of Plant Protection/Key Laboratory of Green Prevention and Control of Tropical Plant Diseases and Pests, Ministry of Education, Hainan University, Haikou 570228, China
| | - Wenbo Liu
- College of Plant Protection/Key Laboratory of Green Prevention and Control of Tropical Plant Diseases and Pests, Ministry of Education, Hainan University, Haikou 570228, China
| | - Yu Zhang
- College of Plant Protection/Key Laboratory of Green Prevention and Control of Tropical Plant Diseases and Pests, Ministry of Education, Hainan University, Haikou 570228, China
| | - Chunhua Lin
- College of Plant Protection/Key Laboratory of Green Prevention and Control of Tropical Plant Diseases and Pests, Ministry of Education, Hainan University, Haikou 570228, China
| | - Weiguo Miao
- College of Plant Protection/Key Laboratory of Green Prevention and Control of Tropical Plant Diseases and Pests, Ministry of Education, Hainan University, Haikou 570228, China.
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Guo CT, Peng H, Tong SM, Ying SH, Feng MG. Distinctive role of fluG in the adaptation of Beauveria bassiana to insect-pathogenic lifecycle and environmental stresses. Environ Microbiol 2021; 23:5184-5199. [PMID: 33817932 DOI: 10.1111/1462-2920.15500] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 03/31/2021] [Accepted: 04/02/2021] [Indexed: 12/11/2022]
Abstract
The upstream developmental activation (UDA) pathway comprises three fluG-cored cascades (fluG-flbA, fluG-flbE/B/D and fluG-flbC) that activate the key gene brlA of central developmental pathway (CDP) to initiate conidiation in aspergilli. However, the core role of fluG remains poorly understood in other fungi. Here, we report distinctive role of fluG in the insect-pathogenic lifecycle of Beauveria bassiana. Disruption of fluG resulted in limited conidiation defect, which was mitigated with incubation time and associated with time-course up-regulation/down-regulation of all flb and CDP genes and another fluG-like gene (BBA_06309). In ΔfluG, increased sensitivities to various stresses correlated with repression of corresponding stress-responsive genes. Its virulence through normal cuticle infection was attenuated greatly due to blocked secretion of cuticle-degrading enzymes and delayed formation of hyphal bodies (blastospores) to accelerate proliferation in vivo and host death. In submerged ΔfluG cultures mimicking insect haemolymph, largely increased blastospore production concurred with drastic up-regulation of the CDP genes brlA and abaA, which was associated with earlier up-regulation of most flb genes in the cultures. Our results unveil an essentiality of fluG for fungal adaptation to insect-pathogenic lifecycle and suggest the other fluG-like gene to act as an alternative player in the UDA pathway of B. bassiana.
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Affiliation(s)
- Chong-Tao Guo
- MOE Laboratory of Biosystems Homeostasis & Protection, Institute of Microbiology, College of Life Sciences, Zhejiang University, Zhejiang, Hangzhou, 310058, China
| | - Han Peng
- MOE Laboratory of Biosystems Homeostasis & Protection, Institute of Microbiology, College of Life Sciences, Zhejiang University, Zhejiang, Hangzhou, 310058, China
| | - Sen-Miao Tong
- College of Agricultural and Food Science, Zhejiang A & F University, Lin'an, Zhejiang, 311300, China
| | - Sheng-Hua Ying
- MOE Laboratory of Biosystems Homeostasis & Protection, Institute of Microbiology, College of Life Sciences, Zhejiang University, Zhejiang, Hangzhou, 310058, China
| | - Ming-Guang Feng
- MOE Laboratory of Biosystems Homeostasis & Protection, Institute of Microbiology, College of Life Sciences, Zhejiang University, Zhejiang, Hangzhou, 310058, China
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Abstract
The fungal zinc finger transcription factor NsdC is named after, and is best known for, its essential role in sexual reproduction (never in sexual development). In previous studies with Aspergillus nidulans, it was also shown to have roles in promotion of vegetative growth and suppression of asexual conidiation. In this study, the function of the nsdC homologue in the opportunistic human pathogen A. fumigatus was investigated. NsdC was again found to be essential for sexual development, with deletion of the nsdC gene in both MAT1-1 and MAT1-2 mating partners of a cross leading to complete loss of fertility. However, a functional copy of nsdC in one mating partner was sufficient to allow sexual reproduction. Deletion of nsdC also led to decreased vegetative growth and allowed conidiation in liquid cultures, again consistent with previous findings. However, NsdC in A. fumigatus was shown to have additional biological functions including response to calcium stress, correct organization of cell wall structure, and response to the cell wall stressors. Furthermore, virulence and host immune recognition were affected. Gene expression studies involving chromatin immunoprecipitation (ChIP) of RNA polymerase II (PolII) coupled to next-generation sequencing (Seq) revealed that deletion of nsdC resulted in changes in expression of over 620 genes under basal growth conditions. This demonstrated that this transcription factor mediates the activity of a wide variety of signaling and metabolic pathways and indicates that despite the naming of the gene, the promotion of sexual reproduction is just one among multiple roles of NsdC.IMPORTANCE Aspergillus fumigatus is an opportunistic human fungal pathogen and the main causal agent of invasive aspergillosis, a life-threatening infection especially in immunocompromised patients. A. fumigatus can undergo both asexual and sexual reproductive cycles, and the regulation of both cycles involves several genes and pathways. Here, we have characterized one of these genetic determinants, the NsdC transcription factor, which was initially identified in a screen of transcription factor null mutants showing sensitivity when exposed to high concentrations of calcium. In addition to its known essential roles in sexual reproduction and control of growth rate and asexual reproduction, we have shown in the present study that A. fumigatus NsdC transcription factor has additional previously unrecognized biological functions including calcium tolerance, cell wall stress response, and correct cell wall organization and functions in virulence and host immune recognition. Our results indicate that NsdC can play novel additional biological functions not directly related to its role played during sexual and asexual processes.
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Genome-Wide Identification and Expression Analysis of the bZIP Transcription Factors in the Mycoparasite Coniothyrium minitans. Microorganisms 2020; 8:microorganisms8071045. [PMID: 32674413 PMCID: PMC7409085 DOI: 10.3390/microorganisms8071045] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 07/09/2020] [Accepted: 07/12/2020] [Indexed: 01/19/2023] Open
Abstract
The basic leucine zipper (bZIP) proteins family is one of the largest and most diverse transcription factors, widely distributed in eukaryotes. However, no information is available regarding the bZIP gene family in Coniothyrium minitans, an important biocontrol agent of the plant pathogen Sclerotinia sclerotiorum. In this study, we identified 34 bZIP genes from the C. minitans genome, which were classified into 8 groups based on their phylogenetic relationships. Intron analysis showed that 28 CmbZIP genes harbored a variable number of introns, and 15 of them shared a feature that intron inserted into the bZIP domain. The intron position in bZIP domain was highly conserved, which was related to recognize the arginine (R) and could be treated as a genomic imprinting. Expression analysis of the CmbZIP genes in response to abiotic stresses indicated that they might play distinct roles in abiotic stress responses. Results showed that 22 CmbZIP genes were upregulated during the later stage of conidial development. Furthermore, transcriptome analysis indicated that CmbZIP genes are involved in different stages of mycoparasitism. Among deletion mutants of four CmbZIPs (CmbZIP07, -09, -13, and -16), only ΔCmbZIP16 mutants significantly reduced its tolerance to the oxidative stress. The other mutants exhibited no significant effects on colony morphology, mycelial growth, conidiation, and mycoparasitism. Taken together, our results suggested that CmbZIP genes play important roles in the abiotic stress responses, conidial development, and mycoparasitism. These results provide comprehensive information of the CmbZIP gene family and lay the foundation for further research on the bZIP gene family regarding their biological functions and evolutionary history.
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The Transcriptional Regulator HbxA Governs Development, Secondary Metabolism, and Virulence in Aspergillus fumigatus. Appl Environ Microbiol 2020; 86:AEM.01779-19. [PMID: 31757831 DOI: 10.1128/aem.01779-19] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 11/18/2019] [Indexed: 12/13/2022] Open
Abstract
Aspergillus fumigatus is the leading cause of invasive aspergillosis, which in immunocompromised patients results in a mortality rate as high as 90%. Earlier studies showed that HbxA is a global regulator in Aspergillus flavus affecting morphological development and secondary metabolism. Here, we determined its role in A. fumigatus, examining whether HbxA influences the regulation of asexual development, natural product biosynthesis, and virulence of this fungus. Our analysis demonstrated that removal of the hbxA gene caused a near-complete loss of conidial production in the mutant strain, as well as a slight reduction in colony growth. Other aspects of asexual development are affected, such as size and germination of conidia. Furthermore, we showed that in A. fumigatus, the loss of hbxA decreased the expression of the brlA central regulatory pathway involved in asexual development, as well as the expression of the "fluffy" genes flbB, flbD, and fluG HbxA was also found to regulate secondary metabolism, affecting the biosynthesis of multiple natural products, including fumigaclavines, fumiquinazolines, and chaetominine. In addition, using a neutropenic mouse infection model, hbxA was found to negatively impact the virulence of A. fumigatus IMPORTANCE The number of immunodepressed individuals is increasing, mainly due to the greater life expectancy in immunodepressed patients due to improvements in modern medical treatments. However, this population group is highly susceptible to invasive aspergillosis. This devastating illness, mainly caused by the fungus Aspergillus fumigatus, is associated with mortality rates reaching 90%. Treatment options for this disease are currently limited, and a better understanding of A. fumigatus genetic regulatory mechanisms is paramount for the design of new strategies to prevent or combat this infection. Our work provides new insight into the regulation of the development, metabolism, and virulence of this important opportunistic pathogen. The transcriptional regulatory gene hbxA has a profound effect on A. fumigatus biology, governing multiple aspects of conidial development. This is relevant since conidia are the main source of inoculum in Aspergillus infections. Importantly, hbxA also regulates the biosynthesis of secondary metabolites and the pathogenicity of this fungus.
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Castellá G, Bragulat MR, Cigliano RA, Cabañes FJ. Transcriptome analysis of non-ochratoxigenic Aspergillus carbonarius strains and interactions between some black aspergilli species. Int J Food Microbiol 2019; 317:108498. [PMID: 31918247 DOI: 10.1016/j.ijfoodmicro.2019.108498] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 12/18/2019] [Accepted: 12/23/2019] [Indexed: 01/07/2023]
Abstract
Aspergillus carbonarius consistently produces large amounts of ochratoxin A (OTA), a mycotoxin with nephrotoxic effects on animals and humans. In the present study, we analyzed the transcriptional changes associated to OTA production in three atypical non-ochratoxigenic strains of A. carbonarius. In addition, in vitro interactions between ochratoxigenic strains of A. carbonarius and A. niger and non-ochratoxigenic strains of A. carbonarius and A. tubingensis were studied in order to evaluate their potential for controlling OTA production. RNA-seq analysis revealed that there are 696 differentially expressed genes identified in the three non-OTA-producing strains, including 280 up-regulated and 333 down-regulated genes. A functional and gene ontology enrichment analysis revealed that the processes related to metabolic and oxidation processes, associated with functions such as oxidoreductase and hydrolase activity were down regulated. All the genes related with OTA biosynthesis in A. carbonarius were the most down-regulated genes in non-ochratoxigenic strains. We also showed that these strains possess a deleterious mutation in the AcOTApks gene required for OTA biosynthesis. Moreover, one of these strains gave the best control of OTA production resulting in an OTA reduction of 98-100% in co-inoculation with an ochratoxigenic strain of A. niger and an OTA reduction of 79-89% with an ochratoxigenic strain of A. carbonarius. Results of this study provided novel insights into the knowledge of the OTA biosynthetic pathway in these non-ochratoxigenic wild strains, and showed the biocontrol potential of these strains.
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Affiliation(s)
- Gemma Castellá
- Veterinary Mycology Group, Department of Animal Health and Anatomy, Universitat Autònoma de Barcelona, Bellaterra, Catalonia, Spain
| | - M Rosa Bragulat
- Veterinary Mycology Group, Department of Animal Health and Anatomy, Universitat Autònoma de Barcelona, Bellaterra, Catalonia, Spain
| | | | - F Javier Cabañes
- Veterinary Mycology Group, Department of Animal Health and Anatomy, Universitat Autònoma de Barcelona, Bellaterra, Catalonia, Spain.
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The phosphatase gene MaCdc14 negatively regulates UV-B tolerance by mediating the transcription of melanin synthesis-related genes and contributes to conidiation in Metarhizium acridum. Curr Genet 2019; 66:141-153. [PMID: 31256233 DOI: 10.1007/s00294-019-01008-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 06/19/2019] [Accepted: 06/22/2019] [Indexed: 10/26/2022]
Abstract
Reversible phosphorylation of proteins regulated by protein kinases and phosphatases mediate multiple biological events in eukaryotes. In this study, a dual-specificity cell division cycle 14 phosphatase, MaCdc14, was functionally characterized in Metarhizium acridum. Deletion of MaCdc14 decreased branch numbers, affected septum formation and resulted in multiple nuclei in each hyphal compartment, indicating nuclear division and cytokinesis defects. The spore production capacity was severely impaired with decreased conidial yield and delayed conidiation in MaCdc14-deletion mutant (ΔMaCdc14). The transcription levels of conidiation-related genes were significantly changed after MaCdc14 inactivation. The morphology of conidia was uneven in size and the germination rate of conidia was increased in ΔMaCdc14. In addition, ΔMaCdc14 displayed significantly enhanced conidial tolerance to ultraviolet (UV) irradiation but had no significant effect on the thermotolerance, the sensitivities to cell wall damage reagents, osmotic and oxidative stresses, and virulence compared to the wild-type strain and complementary transformant. Furthermore, the pigmentation of ΔMaCdc14 was increased by the upregulated expression of melanin synthesis-related genes, which may result in the enhanced UV-B tolerance of ΔMaCdc14. In summary, MaCdc14 negatively regulated UV-B tolerance by mediating the transcription of melanin synthesis-related genes, contributed to conidiation by regulating the expression levels of conidiation-related genes and also played important roles in cytokinesis and morphogenesis in Metarhizium acridum.
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Yin W, Cui P, Wei W, Lin Y, Luo C. Genome-wide identification and analysis of the basic leucine zipper (bZIP) transcription factor gene family in Ustilaginoidea virens. Genome 2017; 60:1051-1059. [DOI: 10.1139/gen-2017-0089] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The basic leucine zipper (bZIP) transcription factor (TF) family is one of the largest and most diverse TF families widely distributed across the eukaryotes. The bZIP TF family plays an important role in growth, development, and response to abiotic or biotic stresses, which have been well characterized in plants, but not in plant pathogenic fungi. In this study, we performed genome-wide and systematic bioinformatics analysis of bZIP genes in the fungus Ustilaginoidea virens, the causal agent of rice false smut disease. We identified 28 bZIP family members in the U. virens genome by searching for the bZIP domain in predicted genes. The gene structures, motifs, and phylogenetic relationships were analyzed for bZIP genes in U. virens (UvbZIP). Together with bZIP proteins from two other fungi, the bZIP genes can be divided into eight groups according to their phylogenetic relationships. Based on RNA-Seq data, the expression profiles of UvbZIP genes at different infection stages were evaluated. Results showed that 17 UvbZIP genes were up-regulated during the infection period. Furthermore, 11 infection-related UvbZIP genes were investigated under H2O2 stress and the expression level of eight genes were changed, which confirmed their role in stress tolerance and pathogenicity. In summary, our genome-wide systematic characterization and expression analysis of UvbZIP genes provided insight into the molecular function of these genes in U. virens and provides a reference for other pathogens.
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Affiliation(s)
- Weixiao Yin
- Department of Plant Protection, College of Plant Science and Technology and the Key Lab of Crop Disease Monitoring & Safety Control in Hubei Province, Huazhong Agricultural University, Wuhan 430070, China
- Department of Plant Protection, College of Plant Science and Technology and the Key Lab of Crop Disease Monitoring & Safety Control in Hubei Province, Huazhong Agricultural University, Wuhan 430070, China
| | - Peng Cui
- Department of Plant Protection, College of Plant Science and Technology and the Key Lab of Crop Disease Monitoring & Safety Control in Hubei Province, Huazhong Agricultural University, Wuhan 430070, China
- Department of Plant Protection, College of Plant Science and Technology and the Key Lab of Crop Disease Monitoring & Safety Control in Hubei Province, Huazhong Agricultural University, Wuhan 430070, China
| | - Wei Wei
- Department of Plant Protection, College of Plant Science and Technology and the Key Lab of Crop Disease Monitoring & Safety Control in Hubei Province, Huazhong Agricultural University, Wuhan 430070, China
- Department of Plant Protection, College of Plant Science and Technology and the Key Lab of Crop Disease Monitoring & Safety Control in Hubei Province, Huazhong Agricultural University, Wuhan 430070, China
| | - Yang Lin
- Department of Plant Protection, College of Plant Science and Technology and the Key Lab of Crop Disease Monitoring & Safety Control in Hubei Province, Huazhong Agricultural University, Wuhan 430070, China
- Department of Plant Protection, College of Plant Science and Technology and the Key Lab of Crop Disease Monitoring & Safety Control in Hubei Province, Huazhong Agricultural University, Wuhan 430070, China
| | - Chaoxi Luo
- Department of Plant Protection, College of Plant Science and Technology and the Key Lab of Crop Disease Monitoring & Safety Control in Hubei Province, Huazhong Agricultural University, Wuhan 430070, China
- Department of Plant Protection, College of Plant Science and Technology and the Key Lab of Crop Disease Monitoring & Safety Control in Hubei Province, Huazhong Agricultural University, Wuhan 430070, China
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Fang Y, Xiong D, Tian L, Tang C, Wang Y, Tian C. Functional characterization of two bZIP transcription factors in Verticillium dahliae. Gene 2017; 626:386-394. [PMID: 28578019 DOI: 10.1016/j.gene.2017.05.061] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 05/26/2017] [Accepted: 05/30/2017] [Indexed: 12/24/2022]
Abstract
bZIP transcription factors play various biological roles in stress responses, conidiation, and pathogenicity in pathogenic fungi. Here, we report two bZIP transcription factors (VDAG_08640 and VDAG_08676) of Verticillium dahliae, which were differentially expressed during microsclerotia development and induced by hydrogen peroxide as well. We find that deletion of either gene does not affect microsclerotia formation and the sensitivity to hydrogen peroxide; however, the mutants manifest decreased activity of extracellular peroxidase and laccase. Other phenotypic characterization reveals that VDAG_08676 disruption results in significant reduction of conidial production and virulence, while VDAG_08640 disruption does not lead to observable phenotypic variances compared with the wild-type strain. To elucidate whether they exhibit functional redundancy, double deletion mutants were generated. The double deletion mutants show remarkably increased sensitivity to hydrogen peroxide stress, whereas the two genes are not involved in microsclerotia formation. Taken together, our data demonstrate that a bZIP transcription factor gene VDAG_08676 is involved in the conidial production, oxidative stress response and virulence which may lay a foundation for further analysis of other bZIP transcription factors in V. dahliae.
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Affiliation(s)
- Yulin Fang
- Beijing Key Laboratory for Forest Pest Control, College of Forestry, Beijing Forestry University, Beijing, China
| | - Dianguang Xiong
- Beijing Key Laboratory for Forest Pest Control, College of Forestry, Beijing Forestry University, Beijing, China
| | - Longyan Tian
- Beijing Key Laboratory for Forest Pest Control, College of Forestry, Beijing Forestry University, Beijing, China
| | - Chen Tang
- Beijing Key Laboratory for Forest Pest Control, College of Forestry, Beijing Forestry University, Beijing, China
| | - Yonglin Wang
- Beijing Key Laboratory for Forest Pest Control, College of Forestry, Beijing Forestry University, Beijing, China.
| | - Chengming Tian
- Beijing Key Laboratory for Forest Pest Control, College of Forestry, Beijing Forestry University, Beijing, China
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Negative regulation and developmental competence in Aspergillus. Sci Rep 2016; 6:28874. [PMID: 27364479 PMCID: PMC4929475 DOI: 10.1038/srep28874] [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: 03/21/2016] [Accepted: 05/16/2016] [Indexed: 12/14/2022] Open
Abstract
Asexual development (conidiation) in the filamentous fungus Aspergillus nidulans is governed by orchestrated gene expression. The three key negative regulators of conidiation SfgA, VosA, and NsdD act at different control point in the developmental genetic cascade. Here, we have revealed that NsdD is a key repressor affecting the quantity of asexual spores in Aspergillus. Moreover, nullifying both nsdD and vosA results in abundant formation of the development specific structure conidiophores even at 12 h of liquid culture, and near constitutive activation of conidiation, indicating that acquisition of developmental competence involves the removal of negative regulation exerted by both NsdD and VosA. NsdD's role in repressing conidiation is conserved in other aspergilli, as deleting nsdD causes enhanced and precocious activation of conidiation in Aspergillus fumigatus or Aspergillus flavus. In vivo NsdD-DNA interaction analyses identify three NsdD binding regions in the promoter of the essential activator of conidiation brlA, indicating a direct repressive role of NsdD in conidiation. Importantly, loss of flbC or flbD encoding upstream activators of brlA in the absence of nsdD results in delayed activation of brlA, suggesting distinct positive roles of FlbC and FlbD in conidiation. A genetic model depicting regulation of conidiation in A. nidulans is presented.
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Lei Y, Liu G, Yao G, Li Z, Qin Y, Qu Y. A novel bZIP transcription factor ClrC positively regulates multiple stress responses, conidiation and cellulase expression in Penicillium oxalicum. Res Microbiol 2016; 167:424-35. [PMID: 27012606 DOI: 10.1016/j.resmic.2016.03.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Revised: 01/19/2016] [Accepted: 03/11/2016] [Indexed: 12/16/2022]
Abstract
Cellulase production in filamentous fungi is largely regulated at the transcriptional level, and several transcription factors have been reported to be involved in this process. In this study, we identified ClrC, a novel transcription factor in cellulase production in Penicillium oxalicum. ClrC and its orthologs have a highly conserved basic leucine zipper (bZIP) DNA binding domain, and their biological functions have not been explored. Deletion of clrC resulted in pleiotropic effects, including altered growth, reduced conidiation and increased sensitivity to oxidative and cell wall stresses. In particular, the clrC deletion mutant ΔclrC showed 46.1% ± 8.1% and 58.0% ± 8.7% decreases in production of filter paper enzyme and xylanase activities in cellulose medium, respectively. In contrast, 57.4% ± 10.0% and 70.9% ± 19.4% increased production of filter paper enzyme, and xylanase was observed in the clrC overexpressing strain, respectively. The transcription levels of major cellulase genes, as well as two cellulase transcriptional activator genes, clrB and xlnR, were significantly downregulated in ΔclrC, but substantially upregulated in clrC overexpressing strains. Furthermore, we observed that the absence of ClrC reduced full induction of cellulase expression even in the clrB overexpressing strain. These results indicated that ClrC is a novel and efficient engineering target for improving cellulolytic enzyme production in filamentous fungi.
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Affiliation(s)
- Yunfeng Lei
- State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Shan Da Nan Road 27, Jinan, Shandong 250100, PR China
| | - Guodong Liu
- State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Shan Da Nan Road 27, Jinan, Shandong 250100, PR China
| | - Guangshan Yao
- State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Shan Da Nan Road 27, Jinan, Shandong 250100, PR China
| | - Zhonghai Li
- State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Shan Da Nan Road 27, Jinan, Shandong 250100, PR China
| | - Yuqi Qin
- State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Shan Da Nan Road 27, Jinan, Shandong 250100, PR China; National Glycoengineering Research Center, Shandong University, Shan Da Nan Road 27, Jinan, Shandong 250100, PR China
| | - Yinbo Qu
- State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Shan Da Nan Road 27, Jinan, Shandong 250100, PR China; National Glycoengineering Research Center, Shandong University, Shan Da Nan Road 27, Jinan, Shandong 250100, PR China.
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26
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Park HS, Yu JH. Developmental regulators in Aspergillus fumigatus. J Microbiol 2016; 54:223-31. [DOI: 10.1007/s12275-016-5619-5] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 12/28/2015] [Accepted: 12/30/2015] [Indexed: 12/29/2022]
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Yao G, Li Z, Wu R, Qin Y, Liu G, Qu Y. Penicillium oxalicum PoFlbC regulates fungal asexual development and is important for cellulase gene expression. Fungal Genet Biol 2016; 86:91-102. [DOI: 10.1016/j.fgb.2015.12.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 12/21/2015] [Accepted: 12/22/2015] [Indexed: 12/25/2022]
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Keller NP. Translating biosynthetic gene clusters into fungal armor and weaponry. Nat Chem Biol 2015; 11:671-7. [PMID: 26284674 DOI: 10.1038/nchembio.1897] [Citation(s) in RCA: 177] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 07/23/2015] [Indexed: 01/06/2023]
Abstract
Filamentous fungi are renowned for the production of a diverse array of secondary metabolites (SMs) where the genetic material required for synthesis of a SM is typically arrayed in a biosynthetic gene cluster (BGC). These natural products are valued for their bioactive properties stemming from their functions in fungal biology, key among those protection from abiotic and biotic stress and establishment of a secure niche. The producing fungus must not only avoid self-harm from endogenous SMs but also deliver specific SMs at the right time to the right tissue requiring biochemical aid. This review highlights functions of BGCs beyond the enzymatic assembly of SMs, considering the timing and location of SM production and other proteins in the clusters that control SM activity. Specifically, self-protection is provided by both BGC-encoded mechanisms and non-BGC subcellular containment of toxic SM precursors; delivery and timing is orchestrated through cellular trafficking patterns and stress- and developmental-responsive transcriptional programs.
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Affiliation(s)
- Nancy P Keller
- Department of Bacteriology and Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, Wisconsin, USA
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Transcription Factor SomA Is Required for Adhesion, Development and Virulence of the Human Pathogen Aspergillus fumigatus. PLoS Pathog 2015; 11:e1005205. [PMID: 26529322 PMCID: PMC4631450 DOI: 10.1371/journal.ppat.1005205] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 09/13/2015] [Indexed: 11/19/2022] Open
Abstract
The transcription factor Flo8/Som1 controls filamentous growth in Saccharomyces cerevisiae and virulence in the plant pathogen Magnaporthe oryzae. Flo8/Som1 includes a characteristic N-terminal LUG/LUH-Flo8-single-stranded DNA binding (LUFS) domain and is activated by the cAMP dependent protein kinase A signaling pathway. Heterologous SomA from Aspergillus fumigatus rescued in yeast flo8 mutant strains several phenotypes including adhesion or flocculation in haploids and pseudohyphal growth in diploids, respectively. A. fumigatus SomA acts similarly to yeast Flo8 on the promoter of FLO11 fused with reporter gene (LacZ) in S. cerevisiae. FLO11 expression in yeast requires an activator complex including Flo8 and Mfg1. Furthermore, SomA physically interacts with PtaB, which is related to yeast Mfg1. Loss of the somA gene in A. fumigatus resulted in a slow growth phenotype and a block in asexual development. Only aerial hyphae without further differentiation could be formed. The deletion phenotype was verified by a conditional expression of somA using the inducible Tet-on system. A adherence assay with the conditional somA expression strain indicated that SomA is required for biofilm formation. A ptaB deletion strain showed a similar phenotype supporting that the SomA/PtaB complex controls A. fumigatus biofilm formation. Transcriptional analysis showed that SomA regulates expression of genes for several transcription factors which control conidiation or adhesion of A. fumigatus. Infection assays with fertilized chicken eggs as well as with mice revealed that SomA is required for pathogenicity. These data corroborate a complex control function of SomA acting as a central factor of the transcriptional network, which connects adhesion, spore formation and virulence in the opportunistic human pathogen A. fumigatus. Invasive fungal infections affecting immunocompromised patients are emerging worldwide. Among various human fungal pathogens, Aspergillus fumigatus is one of the most common molds causing severe invasive aspergillosis in immunocompromised patients. The conidia, which can evade from innate immunity and adhere to epithelial cells of alveoli in human lungs will start to germinate and cause the disease. Currently, the understanding of the molecular mechanisms of adherence of fungal cells to hosts is scarce. The transcription factor Flo8 controls adhesion to biotic or abiotic surfaces and morphological development in baker’s yeast. Flo8 homologues in the dimorphic human pathogenic yeast Candida albicans or the filamentous plant pathogen Magnaporthe oryzae are required for development and virulence. We found in this study that the Flo8 homologue SomA of A. fumigatus is required for adhesion and conidiation. Two independent invasive aspergillosis assays using chicken eggs or mouse demonstrated that deletion of the corresponding gene resulted in attenuated virulence. SomA represents an important fungal transcription factor at the interface between adherence, asexual spore formation and pathogenicity in an important opportunistic human pathogen.
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Park AR, Son H, Min K, Park J, Goo JH, Rhee S, Chae SK, Lee YW. Autoregulation of ZEB2 expression for zearalenone production in Fusarium graminearum. Mol Microbiol 2015; 97:942-56. [PMID: 26036360 DOI: 10.1111/mmi.13078] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/31/2015] [Indexed: 12/30/2022]
Abstract
Several Fusarium species produce the polyketide mycotoxin zearalenone (ZEA), a causative agent of hyperestrogenic syndrome in animals that is often found in F. graminearum-infected cereals in temperate regions. The ZEA biosynthetic cluster genes PKS4, PKS13, ZEB1 and ZEB2 encode a reducing polyketide synthase, a non-reducing polyketide synthase, an isoamyl alcohol oxidase and a transcription factor respectively. In this study, the production of two isoforms (ZEB2L and ZEB2S) from the ZEB2 gene in F. graminearum via an alternative promoter was characterized. ZEB2L contains a basic leucine zipper (bZIP) DNA-binding domain at the N-terminus, whereas ZEB2S is an N-terminally truncated form of ZEB2L that lacks the bZIP domain. Interestingly, ZEA triggers the induction of both ZEB2L and ZEB2S transcription. ZEB2L and ZEB2S interact with each other to form a heterodimer that regulates ZEA production by reducing the binding affinity of ZEB2L for the ZEB2L gene promoter. Our study provides insight into the autoregulation of ZEB2 expression by alternative promoter usage and a feedback loop during ZEA production; this regulatory mechanism is similar to that observed in higher eukaryotes.
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Affiliation(s)
- Ae Ran Park
- Department of Agricultural Biotechnology and Center for Fungal Pathogenesis, Seoul National University, 151-921, Seoul, Korea
| | - Hokyoung Son
- Department of Agricultural Biotechnology and Center for Fungal Pathogenesis, Seoul National University, 151-921, Seoul, Korea
| | - Kyunghun Min
- Department of Agricultural Biotechnology and Center for Fungal Pathogenesis, Seoul National University, 151-921, Seoul, Korea
| | - Jinseo Park
- Department of Agricultural Biotechnology and Center for Fungal Pathogenesis, Seoul National University, 151-921, Seoul, Korea
| | - Jae Hwan Goo
- Jeonnam Nano Bio Research Center, 515-853, Jangseong, Korea
| | - Sangkee Rhee
- Department of Agricultural Biotechnology and Center for Fungal Pathogenesis, Seoul National University, 151-921, Seoul, Korea
| | - Suhn-Kee Chae
- Department of Biochemistry, Paichai University, 302-735, Daejeon, Korea
| | - Yin-Won Lee
- Department of Agricultural Biotechnology and Center for Fungal Pathogenesis, Seoul National University, 151-921, Seoul, Korea
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Proteomic analyses reveal the key roles of BrlA and AbaA in biogenesis of gliotoxin in Aspergillus fumigatus. Biochem Biophys Res Commun 2015; 463:428-33. [PMID: 26032501 DOI: 10.1016/j.bbrc.2015.05.090] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 05/28/2015] [Indexed: 11/24/2022]
Abstract
The opportunistic human pathogenic fungus Aspergillus fumigatus primarily reproduces by forming a large number of asexual spores (conidia). Sequential activation of the central regulators BrlA, AbaA and WetA is necessary for the fungus to undergo asexual development. In this study, to address the presumed roles of these key developmental regulators during proliferation of the fungus, we analyzed and compared the proteomes of vegetative cells of wild type (WT) and individual mutant strains. Approximately 1300 protein spots were detectable from 2-D electrophoresis gels. Among these, 13 proteins exhibiting significantly altered accumulation levels were further identified by ESI-MS/MS. Markedly, we found that the GliM and GliT proteins associated with gliotoxin (GT) biosynthesis and self-protection of the fungus from GT were significantly down-regulated in the ΔabaA and ΔbrlA mutants. Moreover, mRNA levels of other GT biosynthetic genes including gliM, gliP, gliT, and gliZ were significantly reduced in both mutant strains, and no and low levels of GT were detectable in the ΔbrlA and ΔabaA mutant strains, respectively. As GliT is required for the protection of the fungus from GT, growth of the ΔbrlA mutant with reduced levels of GliT was severely impaired by exogenous GT. Our studies demonstrate that AbaA and BrlA positively regulate expression of the GT biosynthetic gene cluster in actively growing vegetative cells, and likely bridge morphological and chemical development during the life-cycle of A. fumigatus.
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Resistance is not futile: gliotoxin biosynthesis, functionality and utility. Trends Microbiol 2015; 23:419-28. [PMID: 25766143 DOI: 10.1016/j.tim.2015.02.005] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Revised: 02/02/2015] [Accepted: 02/17/2015] [Indexed: 12/27/2022]
Abstract
Gliotoxin biosynthesis is encoded by the gli gene cluster in Aspergillus fumigatus. The biosynthesis of gliotoxin is influenced by a suite of transcriptionally-active regulatory proteins and a bis-thiomethyltransferase. A self-protection system against gliotoxin is present in A. fumigatus. Several additional metabolites are also produced via the gliotoxin biosynthetic pathway. Moreover, the biosynthesis of unrelated natural products appears to be influenced either by gliotoxin or by the activity of specific reactions within the biosynthetic pathway. The activity of gliotoxin against animal cells and fungi, often mediated by interference with redox homeostasis or protein modification, is revealing new metabolic interactions within eukaryotic systems. Nature has provided a most useful natural product with which to reveal some of its many molecular secrets.
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Alkhayyat F, Chang Kim S, Yu JH. Genetic control of asexual development in aspergillus fumigatus. ADVANCES IN APPLIED MICROBIOLOGY 2015; 90:93-107. [PMID: 25596030 DOI: 10.1016/bs.aambs.2014.09.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Aspergillus fumigatus is one of the most common fungi found in the environment. It is an opportunistic human pathogen causing invasive pulmonary aspergillosis with a high mortality rate in immunocompromised patients. Conidia, the asexual spores, serve as the main dispersal and infection agent allowing entrance of the fungus into the host through the respiratory tract. Therefore, understanding the asexual developmental process that gives rise to the conidia is of great interest to the scientific community and is currently the focus of an immense load of research being conducted. We have been studying the genetic basis that controls asexual development and gliotoxin biosynthesis in A. fumigatus. In this review, we discuss the genetic regulatory system that dictates conidiation in this important fungus by covering the roles of crucial genetic factors from the upstream heterotrimeric G-protein signaling components to the more specific downstream central activators of the conidiation pathway. In addition, other key asexual regulators including the velvet regulators, the Flb proteins and their associated regulatory factors are discussed.
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Affiliation(s)
| | - Sun Chang Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Dae-Jon, Republic of Korea
| | - Jae-Hyuk Yu
- University of Wisconsin-Madison, MSB, Madison, WI, USA
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Tang W, Ru Y, Hong L, Zhu Q, Zuo R, Guo X, Wang J, Zhang H, Zheng X, Wang P, Zhang Z. System-wide characterization of bZIP transcription factor proteins involved in infection-related morphogenesis of Magnaporthe oryzae. Environ Microbiol 2014; 17:1377-96. [PMID: 25186614 DOI: 10.1111/1462-2920.12618] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 08/29/2014] [Accepted: 09/01/2014] [Indexed: 12/21/2022]
Abstract
The basic leucine zipper (bZIP) domain-containing transcription factors (TFs) function as key regulators of cellular growth and differentiation in eukaryotic organisms including fungi. We have previously identified MoAp1 and MoAtf1 as bZIP TFs in Magnaporthe oryzae and demonstrated that they regulate the oxidative stress response and are critical in conidiogenesis and pathogenicity. Studies of bZIP proteins could provide a novel strategy for controlling rice blast, but a systematic examination of the bZIP proteins has not been carried out. Here, we identified 19 additional bZIP TFs and characterized their functions. We found that the majority of these TFs exhibit active functions, most notably, in conidiogenesis. We showed that MoHac1 regulates the endoplasmic reticulum stress response through a conserved unfolded protein response pathway, MoMetR controls amino acid metabolism to govern growth and differentiation, and MoBzip10 governs appressorium function and invasive hyphal growth. Moreover, MoBzip5 participates in appressorium formation through a pathway distinct from that MoBzip10, and MoMeaB appears to exert a regulatory role through nutrient uptake and nitrogen utilization. Collectively, our results provide insights into shared and specific functions associated with each of these TFs and link the regulatory roles to the fungal growth, conidiation, appressorium formation, host penetration and pathogenicity.
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Affiliation(s)
- Wei Tang
- Department of Plant Pathology, College of Plant Protection, Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Ministry of Education, Nanjing, 210095, China
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Qiu L, Wang JJ, Chu ZJ, Ying SH, Feng MG. Phytochrome controls conidiation in response to red/far-red light and daylight length and regulates multistress tolerance inBeauveria bassiana. Environ Microbiol 2014; 16:2316-28. [DOI: 10.1111/1462-2920.12486] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 04/03/2014] [Indexed: 12/13/2022]
Affiliation(s)
- Lei Qiu
- Institute of Microbiology; College of Life Sciences; Zhejiang University; Hangzhou Zhejiang China
| | - Juan-Juan Wang
- Institute of Microbiology; College of Life Sciences; Zhejiang University; Hangzhou Zhejiang China
| | - Zhen-Jian Chu
- Institute of Microbiology; College of Life Sciences; Zhejiang University; Hangzhou Zhejiang China
| | - Sheng-Hua Ying
- Institute of Microbiology; College of Life Sciences; Zhejiang University; Hangzhou Zhejiang China
| | - Ming-Guang Feng
- Institute of Microbiology; College of Life Sciences; Zhejiang University; Hangzhou Zhejiang China
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36
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Molecular mechanisms of Aspergillus flavus secondary metabolism and development. Fungal Genet Biol 2014; 66:11-8. [DOI: 10.1016/j.fgb.2014.02.008] [Citation(s) in RCA: 133] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Revised: 02/21/2014] [Accepted: 02/25/2014] [Indexed: 12/16/2022]
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37
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Chen Y, Zhu J, Ying SH, Feng MG. Three mitogen-activated protein kinases required for cell wall integrity contribute greatly to biocontrol potential of a fungal entomopathogen. PLoS One 2014; 9:e87948. [PMID: 24498410 PMCID: PMC3912201 DOI: 10.1371/journal.pone.0087948] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Accepted: 12/30/2013] [Indexed: 01/26/2023] Open
Abstract
Bck1, Mkk1 and Slt2 are three mitogen-activated protein (MAP) kinases constituting cell wall integrity (CWI) pathway that may control multi-stress responses via crosstalk with high-osmolarity glycerol (HOG) pathway in budding yeast. In this study, Bck1, Mkk1 and Slt2 orthologues in Beauveria bassiana were confirmed as the three-module cascade essential for CWI because cell wall impairment occurred in the hyphae and conidia of Δbck1, Δmkk1 and Δslt2 examined in multiple experiments. Strikingly, all the deletion mutants became more sensitive to hyperosmotic NaCl and sorbitol with the Western blot of Hog1 phosphorylation being weakened in Δbck1 and absent in Δmkk1 and Δslt2. Apart from crossing responses to cell wall perturbation and high osmolarity, three deletion mutants exhibited faster growth and conidiation on nutrition-rich medium, much less virulence to Galleria mellonella larvae, and higher sensitivity to nutritional, fungicidal, thermal and UV-B irradiative stresses, accompanied with less accumulation of intracellular mannitol and trehalose. Moreover, Δmkk1 and Δslt2 were equally more sensitive to all the stresses of different types except wet-heat stress than wild type and more or less different from Δbck1 in sensitivity to most of the stresses despite their null responses to two oxidants. All the changes in three deletion mutants were restored by each targeted gene complementation. Taken together, the CWI-required Bck1, Mkk1 and Slt2 are all positive, but differential, regulators of multi-stress tolerance and virulence perhaps due to interplay with the HOG pathway essential for osmoregulation, thereby contributing greatly to the biocontrol potential of the fungal entomopathogen.
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Affiliation(s)
- Ying Chen
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
| | - Jing Zhu
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
| | - Sheng-Hua Ying
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
| | - Ming-Guang Feng
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
- * E-mail:
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Wang J, Liu J, Hu Y, Ying SH, Feng MG. Cytokinesis-required Cdc14 is a signaling hub of asexual development and multi-stress tolerance in Beauveria bassiana. Sci Rep 2013; 3:3086. [PMID: 24169500 PMCID: PMC3812655 DOI: 10.1038/srep03086] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Accepted: 10/14/2013] [Indexed: 12/16/2022] Open
Abstract
A dual-specificity, paralogue-free Cdc14 phosphatase was located in the nuclei of Beauveria bassiana (filamentous entomopathogen) and functionally characterized. Inactivation of cdc14 caused defective cytokinesis due to multinucleate cells formed in Δcdc14 and 89% decrease of blastospore production, followed by slower growth and a loss of ≥ 96% conidial yield under normal conditions. These defects coincided well with drastic down-regulation of 25 genes required for mitosis and conidiation. Moreover, Δcdc14 became hypersensitive to oxidative, osmotic, and cell wall and mitosis perturbing stresses, and lost 41−70% of conidial thermotolerance, UV-B resistance and virulence, accompanied with transcriptional down-regualtion of various signaling factors and stress-responsive effectors and depressed phosphorylation signals of Hog1 and Slt2 in high-osmolarity glycerol and cell-wall integrity pathways. All changes were well restored by rescuing cdc14. Our findings indicate that Cdc14 vital for the fungal cytokinesis acts as a signaling hub in regulating not only asexual development but multi-stress responses and virulence.
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Affiliation(s)
- Jie Wang
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, People's Republic of China
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Chi MH, Craven KD. Oxygen and an extracellular phase transition independently control central regulatory genes and conidiogenesis in Aspergillus fumigatus. PLoS One 2013; 8:e74805. [PMID: 24040343 PMCID: PMC3764054 DOI: 10.1371/journal.pone.0074805] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 08/06/2013] [Indexed: 11/18/2022] Open
Abstract
Conidiogenesis is the primary process for asexual reproduction in filamentous fungi. As the conidia resulting from the conidiogenesis process are primarily disseminated via air currents and/or water, an outstanding question has been how fungi recognize aerial environments suitable for conidial development. In this study, we documented the somewhat complex development of the conidia-bearing structures, termed conidiophores, from several Aspergillus species in a subsurface (gel-phase) layer of solid media. A subset of the isolates studied was able to develop conidiophores in a gel-phase environment, but exposure to the aeriform environment was required for the terminal developmental transition from phialide cells to conidia. The remaining Aspergilli could not initiate the conidiogenesis process until they were exposed to the aeriform environment. Our observations of conidiophore development in high or low oxygen conditions in both aeriform and gel-phase environments revealed that oxygen and the aeriform state are positive environmental factors for inducing conidiogenesis in most of the aspergilli tested in this study. Transcriptional analysis using A. fumigatus strain AF293 confined to either the aeriform or gel-phase environments revealed that expression of a key regulatory gene for conidiophore development (AfubrlA) is facilitated by oxygen while expression of another regulatory gene controlling conidia formation from phialides (AfuabaA) was repressed regardless of oxygen levels in the gel-embedded environment. Furthermore, by comparing the developmental behavior of conidiation-defective mutants lacking genes controlling various regulatory checkpoints throughout the conidiogenesis pathway, we propose that this aerial response by the fungus requires both oxygen and the phase transition (solid to aeriform), with these environmental signals integrating into the upstream regulatory pathway and central regulatory pathway of conidiogenesis, respectively. Our findings provide not only novel insight into how fungi respond to an aerial environment to trigger development for airborne conidia production but also the relationship between environmental factors and conidiogenesis regulation in aspergilli.
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Affiliation(s)
- Myoung-Hwan Chi
- Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, Oklahoma, United States of America
| | - Kelly D. Craven
- Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, Oklahoma, United States of America
- * E-mail:
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Krijgsheld P, Bleichrodt R, van Veluw G, Wang F, Müller W, Dijksterhuis J, Wösten H. Development in Aspergillus. Stud Mycol 2013; 74:1-29. [PMID: 23450714 PMCID: PMC3563288 DOI: 10.3114/sim0006] [Citation(s) in RCA: 235] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The genus Aspergillus represents a diverse group of fungi that are among the most abundant fungi in the world. Germination of a spore can lead to a vegetative mycelium that colonizes a substrate. The hyphae within the mycelium are highly heterogeneous with respect to gene expression, growth, and secretion. Aspergilli can reproduce both asexually and sexually. To this end, conidiophores and ascocarps are produced that form conidia and ascospores, respectively. This review describes the molecular mechanisms underlying growth and development of Aspergillus.
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Affiliation(s)
- P. Krijgsheld
- Microbiology and Kluyver Centre for Genomics of Industrial Fermentations, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - R. Bleichrodt
- Microbiology and Kluyver Centre for Genomics of Industrial Fermentations, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - G.J. van Veluw
- Microbiology and Kluyver Centre for Genomics of Industrial Fermentations, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - F. Wang
- Microbiology and Kluyver Centre for Genomics of Industrial Fermentations, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - W.H. Müller
- Biomolecular Imaging, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - J. Dijksterhuis
- Applied and Industrial Mycology, CBS-KNAW Fungal Biodiversity Centre, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - H.A.B. Wösten
- Microbiology and Kluyver Centre for Genomics of Industrial Fermentations, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
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Liu Q, Ying SH, Li JG, Tian CG, Feng MG. Insight into the transcriptional regulation of Msn2 required for conidiation, multi-stress responses and virulence of two entomopathogenic fungi. Fungal Genet Biol 2013; 54:42-51. [PMID: 23466345 DOI: 10.1016/j.fgb.2013.02.008] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Revised: 01/12/2013] [Accepted: 02/21/2013] [Indexed: 01/28/2023]
Abstract
Msn2/4 transcription factors in some fungi have null effects on virulence and cellular stress responses. Here we found that the transcriptional regulation of Msn2 orthologs is vital for the conidiation, virulence and multi-stress responses of Beauveria bassiana (Bb) and Metarhizium robertsii (Mr), which lack Msn4 orthologs. Compared to wild-type and complemented strains of each fungus with all similar phenotypes, ΔBbmsn2 and ΔMrmsn2 showed remarkable defects in conidial yield (∼40% decrease) and virulence (∼25% decrease). Both delta mutants lost 20-65% of their tolerances to hyperosmolarity, oxidation, carbendazim, cell wall perturbing and high temperature at 34 °C during colony growth. Their conidia were also significantly (18-41%) less tolerant to oxidation, hyperosmolarity, wet-heat stress at 45 °C and UV-B irradiation. Accompanied with the defective phenotypes, several conidiation- and virulence-associated genes were greatly repressed in ΔBbmsn2 and ΔMrmsn2. Moreover, differentially expressed genes in the transcriptomes of ΔBbmsn2 versus wild type were ∼3% more under oxidative stress, but ∼12% fewer under heat shock, than those in the ΔMrmsn2 counterparts. Many stress-responsive effector genes and cellular signaling factors were remarkably downregulated. Taken together, the two entomopathogens could have evolved somewhat distinct stress-responsive mechanisms finely tuned by Msn2, highlighting the biological significance of Msn2 orthologs for filamentous fungi.
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Affiliation(s)
- Qian Liu
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, People's Republic of China
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Wang J, Zhou G, Ying SH, Feng MG. P-type calcium ATPase functions as a core regulator of Beauveria bassiana growth, conidiation and responses to multiple stressful stimuli through cross-talk with signalling networks. Environ Microbiol 2012. [PMID: 23206243 DOI: 10.1111/1462-2920.12044] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
P-type Ca(2+) -ATPase (Pmr1) is a core element in calcium-calcineurin pathway and evidence for its cross-talk with other signalling pathways in filamentous fungi is of scarcity. Here, we characterized the striking functions of a Golgi Ca(2+) -ATPase (Bbpmr1) in Beauveria bassiana (fungal entomopathogen) by multi-phenotypic and transcriptional analyses under normal and stressful conditions. Bbpmr1 inactivation caused severe defects in nutritional uptake, growth, conidiation and germination under normal conditions, drastic reductions in cell tolerances to oxidative, hyperosmotic, cell wall disturbing and fungicidal stresses and toxic metal ions during colony growth and/or conidial germination, and half loss of the fungal biocontrol potential represented by conidial virulence, thermotolerance and UV-B resistance. Accompanied with the multi-phenotypic defects, four important genes associated with asexual development were repressed by ≥ 75% in ΔBbpmr1 versus wild type, and all or most of stress-responsive genes encoding 14 cascaded proteins in MAPK pathways, two Ras GTPases, two protein kinases, Ssk1-type response regulator, TOR signalling protein, and many downstream enzymes and proteins were greatly downregulated in ΔBbpmr1 under the chemical stresses. Conclusively, Bbpmr1 regulates positively fundamental aspects on B. bassiana biology and environmental adaptation through wide cross-talk with cellular signalling networks including MAPK cascades and those upstream or independent of the cascades.
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Affiliation(s)
- Jie Wang
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, 310058, Zhejiang, China
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Park HS, Bayram O, Braus GH, Kim SC, Yu JH. Characterization of the velvet regulators in Aspergillus fumigatus. Mol Microbiol 2012; 86:937-53. [PMID: 22970834 DOI: 10.1111/mmi.12032] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/05/2012] [Indexed: 01/19/2023]
Abstract
Fungal development and secondary metabolism is intimately associated via activities of the fungi-specific velvet family proteins. Here we characterize the four velvet regulators in the opportunistic human pathogen Aspergillus fumigatus. The deletion of AfuvosA, AfuveA and AfuvelB causes hyperactive asexual development (conidiation) and precocious and elevated accumulation of AfubrlA during developmental progression. Moreover, the absence of AfuvosA, AfuveA or AfuvelB results in the abundant formation of conidiophores and highly increased AfubrlA mRNA accumulation in liquid submerged culture, suggesting that they act as repressors of conidiation. The deletion of AfuvosA or AfuvelB causes a reduction in conidial trehalose amount, long-term spore viability, conidial tolerance to oxidative and UV stresses, and accelerated and elevated conidial germination regardless of the presence or absence of an external carbon source, suggesting an interdependent role of them in many aspects of fungal biology. Genetic studies suggest that AfuAbaA activates AfuvosA and AfuvelB expression during the mid to late phase of conidiation. Finally, the AfuveA null mutation can be fully complemented by Aspergillus nidulans VeA, which can physically interact with AfuVelB and AfuLaeA in vivo. A model depicting the similar yet different roles of the velvet regulators governing conidiation and sporogenesis in A. fumigatus is presented.
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Affiliation(s)
- Hee-Soo Park
- Department of Bacteriology, University of Wisconsin, Madison, WI, USA
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Barker BM, Kroll K, Vödisch M, Mazurie A, Kniemeyer O, Cramer RA. Transcriptomic and proteomic analyses of the Aspergillus fumigatus hypoxia response using an oxygen-controlled fermenter. BMC Genomics 2012; 13:62. [PMID: 22309491 PMCID: PMC3293747 DOI: 10.1186/1471-2164-13-62] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Accepted: 02/06/2012] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND Aspergillus fumigatus is a mold responsible for the majority of cases of aspergillosis in humans. To survive in the human body, A. fumigatus must adapt to microenvironments that are often characterized by low nutrient and oxygen availability. Recent research suggests that the ability of A. fumigatus and other pathogenic fungi to adapt to hypoxia contributes to their virulence. However, molecular mechanisms of A. fumigatus hypoxia adaptation are poorly understood. Thus, to better understand how A. fumigatus adapts to hypoxic microenvironments found in vivo during human fungal pathogenesis, the dynamic changes of the fungal transcriptome and proteome in hypoxia were investigated over a period of 24 hours utilizing an oxygen-controlled fermenter system. RESULTS Significant increases in transcripts associated with iron and sterol metabolism, the cell wall, the GABA shunt, and transcriptional regulators were observed in response to hypoxia. A concomitant reduction in transcripts was observed with ribosome and terpenoid backbone biosynthesis, TCA cycle, amino acid metabolism and RNA degradation. Analysis of changes in transcription factor mRNA abundance shows that hypoxia induces significant positive and negative changes that may be important for regulating the hypoxia response in this pathogenic mold. Growth in hypoxia resulted in changes in the protein levels of several glycolytic enzymes, but these changes were not always reflected by the corresponding transcriptional profiling data. However, a good correlation overall (R(2) = 0.2, p < 0.05) existed between the transcriptomic and proteomics datasets for all time points. The lack of correlation between some transcript levels and their subsequent protein levels suggests another regulatory layer of the hypoxia response in A. fumigatus. CONCLUSIONS Taken together, our data suggest a robust cellular response that is likely regulated both at the transcriptional and post-transcriptional level in response to hypoxia by the human pathogenic mold A. fumigatus. As with other pathogenic fungi, the induction of glycolysis and transcriptional down-regulation of the TCA cycle and oxidative phosphorylation appear to major components of the hypoxia response in this pathogenic mold. In addition, a significant induction of the transcripts involved in ergosterol biosynthesis is consistent with previous observations in the pathogenic yeasts Candida albicans and Cryptococcus neoformans indicating conservation of this response to hypoxia in pathogenic fungi. Because ergosterol biosynthesis enzymes also require iron as a co-factor, the increase in iron uptake transcripts is consistent with an increased need for iron under hypoxia. However, unlike C. albicans and C. neoformans, the GABA shunt appears to play an important role in reducing NADH levels in response to hypoxia in A. fumigatus and it will be intriguing to determine whether this is critical for fungal virulence. Overall, regulatory mechanisms of the A. fumigatus hypoxia response appear to involve both transcriptional and post-transcriptional control of transcript and protein levels and thus provide candidate genes for future analysis of their role in hypoxia adaptation and fungal virulence.
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Affiliation(s)
- Bridget M Barker
- Department of Immunology and Infectious Disease, Montana State University, Bozeman, MT, USA
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Cortese MS, Etxebeste O, Garzia A, Espeso EA, Ugalde U. Elucidation of functional markers from Aspergillus nidulans developmental regulator FlbB and their phylogenetic distribution. PLoS One 2011; 6:e17505. [PMID: 21423749 PMCID: PMC3053368 DOI: 10.1371/journal.pone.0017505] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Accepted: 02/06/2011] [Indexed: 11/18/2022] Open
Abstract
Aspergillus nidulans is a filamentous fungus widely used as a model for biotechnological and clinical research. It is also used as a platform for the study of basic eukaryotic developmental processes. Previous studies identified and partially characterized a set of proteins controlling cellular transformations in this ascomycete. Among these proteins, the bZip type transcription factor FlbB is a key regulator of reproduction, stress responses and cell-death. Our aim here was the prediction, through various bioinformatic methods, of key functional residues and motifs within FlbB in order to inform the design of future laboratory experiments and further the understanding of the molecular mechanisms that control fungal development. A dataset of FlbB orthologs and those of its key interaction partner FlbE was assembled from 40 members of the Pezizomycotina. Unique features were identified in each of the three structural domains of FlbB. The N-terminal region encoded a bZip transcription factor domain with a novel histidine-containing DNA binding motif while the dimerization determinants exhibited two distinct profiles that segregated by class. The C-terminal region of FlbB showed high similarity with the AP-1 family of stress response regulators but with variable patterns of conserved cysteines that segregated by class and order. Motif conservation analysis revealed that nine FlbB orthologs belonging to the Eurotiales order contained a motif in the central region that could mediate interaction with FlbE. The key residues and motifs identified here provide a basis for the design of follow-up experimental investigations. Additionally, the presence or absence of these residues and motifs among the FlbB orthologs could help explain the differences in the developmental programs among fungal species as well as define putative complementation groups that could serve to extend known functional characterizations to other species.
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Affiliation(s)
- Marc S Cortese
- Department of Applied Chemistry, Faculty of Chemistry, University of the Basque Country, San Sebastián, Spain.
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Tao L, Yu JH. AbaA and WetA govern distinct stages of Aspergillus fumigatus development. Microbiology (Reading) 2011; 157:313-326. [DOI: 10.1099/mic.0.044271-0] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The opportunistic human pathogen Aspergillus fumigatus produces a massive number of asexual spores (conidia) as the primary means of dispersal, survival, genome protection and infection of hosts. In this report, we investigate the functions of two developmental regulators, AfuAbaA and AfuWetA, in A. fumigatus. The AfuabaA gene is predicted to encode an ATTS/TEA DNA-binding domain protein and is activated by AfuBrlA during the middle stage of A. fumigatus asexual development (conidiation). The deletion of AfuabaA results in the formation of aberrant conidiophores exhibiting reiterated cylinder-like terminal cells lacking spores. Furthermore, the absence of AfuabaA causes delayed autolysis and cell death, whereas the overexpression of AfuabaA accelerates these processes, indicating an additional role for AfuAbaA. The AfuwetA gene is sequentially activated by AfuAbaA in the late phase of conidiation. The deletion of AfuwetA causes the formation of defective spore walls and a lack of trehalose biogenesis, leading to a rapid loss of spore viability and reduced tolerance to various stresses. This is the first report to demonstrate that WetA is essential for trehalose biogenesis in conidia. Moreover, the absence of AfuwetA causes delayed germ-tube formation and reduced hyphal branching, suggesting a role of AfuWetA in the early phase of fungal growth. A genetic model depicting the regulation of conidiation in A. fumigatus is proposed.
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Affiliation(s)
- Li Tao
- State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing, PR China
- Departments of Bacteriology and Genetics, University of Wisconsin, Madison, WI 53706, USA
| | - Jae-Hyuk Yu
- Departments of Bacteriology and Genetics, University of Wisconsin, Madison, WI 53706, USA
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Yu JH. Regulation of Development in Aspergillus nidulans and Aspergillus fumigatus. MYCOBIOLOGY 2010; 38:229-237. [PMID: 23956662 PMCID: PMC3741515 DOI: 10.4489/myco.2010.38.4.229] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Accepted: 11/16/2010] [Indexed: 06/02/2023]
Abstract
Members of the genus Aspergillus are the most common fungi and all reproduce asexually by forming long chains of conidiospores (or conidia). The impact of various Aspergillus species on humans ranges from beneficial to harmful. For example, several species including Aspergillus oryzae and Aspergillus niger are used in industry for enzyme production and food processing. In contrast, Aspergillus flavus produce the most potent naturally present carcinogen aflatoxins, which contaminate various plant- and animal-based foods. Importantly, the opportunistic human pathogen Aspergillus fumigatus has become the most prevalent airborne fungal pathogen in developed countries, causing invasive aspergillosis in immunocompromised patients with a high mortality rate. A. fumigatus produces a massive number of small hydrophobic conidia as the primary means of dispersal, survival, genome-protection, and infecting hosts. Large-scale genome-wide expression studies can now be conducted due to completion of A. fumigatus genome sequencing. However, genomics becomes more powerful and informative when combined with genetics. We have been investigating the mechanisms underlying the regulation of asexual development (conidiation) and gliotoxin biosynthesis in A. fumigatus, primarily focusing on a characterization of key developmental regulators identified in the model fungus Aspergillus nidulans. In this review, I will summarize our current understanding of how conidiation in two aspergilli is regulated.
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Affiliation(s)
- Jae-Hyuk Yu
- Departments of Bacteriology and Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
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