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Qiu C, Liu Z. Positive selection and functional diversification of transcription factor Cmr1 homologs in Alternaria. Appl Microbiol Biotechnol 2024; 108:133. [PMID: 38229332 DOI: 10.1007/s00253-023-12893-7] [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: 06/30/2023] [Revised: 12/04/2023] [Accepted: 12/07/2023] [Indexed: 01/18/2024]
Abstract
Transcription factor Cmr1 (Colletotrichum melanin regulation 1) and its homologs in several plant fungal pathogens are the regulators of the 1,8-dihydroxynaphthalene (DHN)-melanin biosynthesis pathway and have evolved functional diversification in morphology and pathogenicity. The fungal genus Alternaria comprises the group of "black fungi" that are rich in DHN-melanin in the primary cell wall and septa of the conidia. Some Alternaria species cause many economically important plant diseases worldwide. However, the evolution and function of Cmr1 homologs in Alternaria remain poorly understood. Here, we identified a total of forty-two Cmr1 homologs from forty-two Alternaria spp. and all contained one additional diverse fungal specific transcription factor motif. Phylogenetic analysis indicated the division of these homologs into five major clades and three branches. Dated phylogeny showed the A and D clades diverged latest and earliest, respectively. Molecular evolutionary analyses revealed that three amino acid sites of Cmr1 homologs in Alternaria were the targets of positive selection. Asmr1, the homolog of Cmr1 in the potato early blight pathogen, Alternaria solani was amplified and displayed the sequence conservation at the amino acid level in different A. solani isolates. Asmr1 was further confirmed to have the transcriptional activation activity and was upregulated during the early stage of potato infection. Deletion of asmr1 led to the decreased melanin content and pathogenicity, deformed conidial morphology, and responses to cell wall and fungicide stresses in A. solani. These results suggest positive selection and functional divergence have played a role in the evolution of Cmr1 homologs in Alternaria. KEY POINTS: • Cmr1 homologs were under positive selection in Alternaria species • Asmr1 is a functional transcription factor, involved in spore development, melanin biosynthesis, pathogenicity, and responses to cell wall and fungicide stresses in A. solani • Cmr1 might be used as a potential taxonomic marker of the genus Alternaria.
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Affiliation(s)
- Chaodong Qiu
- Department of Plant Pathology, School of Plant Protection, Anhui Agricultural University, Hefei, Anhui, 230036, China
| | - Zhenyu Liu
- Department of Plant Pathology, School of Plant Protection, Anhui Agricultural University, Hefei, Anhui, 230036, China.
- Anhui Province Key Laboratory of Integrated Pest Management On Crops, Hefei, Anhui, 230036, China.
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Park J, Son H. Antioxidant Systems of Plant Pathogenic Fungi: Functions in Oxidative Stress Response and Their Regulatory Mechanisms. THE PLANT PATHOLOGY JOURNAL 2024; 40:235-250. [PMID: 38835295 DOI: 10.5423/ppj.rw.01.2024.0001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Accepted: 03/23/2024] [Indexed: 06/06/2024]
Abstract
During the infection process, plant pathogenic fungi encounter plant-derived oxidative stress, and an appropriate response to this stress is crucial to their survival and establishment of the disease. Plant pathogenic fungi have evolved several mechanisms to eliminate oxidants from the external environment and maintain cellular redox homeostasis. When oxidative stress is perceived, various signaling transduction pathways are triggered and activate the downstream genes responsible for the oxidative stress response. Despite extensive research on antioxidant systems and their regulatory mechanisms in plant pathogenic fungi, the specific functions of individual antioxidants and their impacts on pathogenicity have not recently been systematically summarized. Therefore, our objective is to consolidate previous research on the antioxidant systems of plant pathogenic fungi. In this review, we explore the plant immune responses during fungal infection, with a focus on the generation and function of reactive oxygen species. Furthermore, we delve into the three antioxidant systems, summarizing their functions and regulatory mechanisms involved in oxidative stress response. This comprehensive review provides an integrated overview of the antioxidant mechanisms within plant pathogenic fungi, revealing how the oxidative stress response contributes to their pathogenicity.
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Affiliation(s)
- Jiyeun Park
- Department of Agricultural Biotechnology, Seoul National University, Seoul 08826, Korea
| | - Hokyoung Son
- Department of Agricultural Biotechnology, Seoul National University, Seoul 08826, Korea
- Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Korea
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3
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Wu PC, Choo YL, Wei SY, Yago JI, Chung KR. Contribution of Autophagy to Cellular Iron Homeostasis and Stress Adaptation in Alternaria alternata. Int J Mol Sci 2024; 25:1123. [PMID: 38256200 PMCID: PMC10816921 DOI: 10.3390/ijms25021123] [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: 11/20/2023] [Revised: 01/04/2024] [Accepted: 01/14/2024] [Indexed: 01/24/2024] Open
Abstract
The tangerine pathotype of Alternaria alternata produces the Alternaria citri toxin (ACT), which elicits a host immune response characterized by the increase in harmful reactive oxygen species (ROS) production. ROS detoxification in A. alternata relies on the degradation of peroxisomes through autophagy and iron acquisition using siderophores. In this study, we investigated the role of autophagy in regulating siderophore and iron homeostasis in A. alternata. Our results showed that autophagy positively influences siderophore production and iron uptake. The A. alternata strains deficient in autophagy-related genes 1 and 8 (ΔAaatg1 and ΔAaatg8) could not thrive without iron, and their adaptability to high-iron environments was also reduced. Furthermore, the ability of autophagy-deficient strains to withstand ROS was compromised. Notably, autophagy deficiency significantly reduced the production of dimerumic acid (DMA), a siderophore in A. alternata, which may contribute to ROS detoxification. Compared to the wild-type strain, ΔAaatg8 was defective in cellular iron balances. We also observed iron-induced autophagy and lipid peroxidation in A. alternata. To summarize, our study indicates that autophagy and maintaining iron homeostasis are interconnected and contribute to the stress resistance and the virulence of A. alternata. These results provide new insights into the complex interplay connecting autophagy, iron metabolism, and fungal pathogenesis in A. alternata.
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Affiliation(s)
- Pei-Ching Wu
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung Hsing University, Taichung 402202, Taiwan; (P.-C.W.); (Y.-L.C.); (S.-Y.W.)
| | - Yen-Ling Choo
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung Hsing University, Taichung 402202, Taiwan; (P.-C.W.); (Y.-L.C.); (S.-Y.W.)
| | - Sian-Yong Wei
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung Hsing University, Taichung 402202, Taiwan; (P.-C.W.); (Y.-L.C.); (S.-Y.W.)
| | - Jonar I. Yago
- Plant Science Department, College of Agriculture, Nueva Vizcaya State University, Bayombong 3700, Philippines;
| | - Kuang-Ren Chung
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung Hsing University, Taichung 402202, Taiwan; (P.-C.W.); (Y.-L.C.); (S.-Y.W.)
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Fernandes C, Casadevall A, Gonçalves T. Mechanisms of Alternaria pathogenesis in animals and plants. FEMS Microbiol Rev 2023; 47:fuad061. [PMID: 37884396 DOI: 10.1093/femsre/fuad061] [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: 05/08/2023] [Revised: 09/18/2023] [Accepted: 10/25/2023] [Indexed: 10/28/2023] Open
Abstract
Alternaria species are cosmopolitan fungi darkly pigmented by melanin that infect numerous plant species causing economically important agricultural spoilage of various food crops. Alternaria spp. also infect animals, being described as entomopathogenic fungi but also infecting warm-blooded animals, including humans. Their clinical importance in human health, as infection agents, lay in the growing number of immunocompromised patients. Moreover, Alternaria spp. are considered some of the most abundant and potent sources of airborne sensitizer allergens causing allergic respiratory diseases, as severe asthma. Among the numerous strategies deployed by Alternaria spp. to attack their hosts, the production of toxins, carrying critical concerns to public health as food contaminant, and the production of hydrolytic enzymes such as proteases, can be highlighted. Alternaria proteases also trigger allergic symptoms in individuals with fungal sensitization, acting as allergens and facilitating antigen access to the host subepithelium. Here, we review the current knowledge about the mechanisms of Alternaria pathogenesis in plants and animals, the strategies used by Alternaria to cope with the host defenses, and the involvement Alternaria allergens and mechanisms of sensitization.
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Affiliation(s)
- Chantal Fernandes
- CNC-UC - Center for Neuroscience and Cell Biology of Coimbra, Rua Larga, 3004-504 Coimbra, Portugal
| | - Arturo Casadevall
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Wolfe Street, Room E5132, Baltimore, Maryland 21205, USA
| | - Teresa Gonçalves
- CNC-UC - Center for Neuroscience and Cell Biology of Coimbra, Rua Larga, 3004-504 Coimbra, Portugal
- FMUC - Faculty of Medicine, University of Coimbra, Rua Larga, 3004-504 Coimbra, Portugal
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Chen Y, Zhang Y, Xu D, Zhang Z, Li B, Tian S. PeAP1-mediated oxidative stress response plays an important role in the growth and pathogenicity of Penicillium expansum. Microbiol Spectr 2023; 11:e0380822. [PMID: 37732795 PMCID: PMC10581040 DOI: 10.1128/spectrum.03808-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 05/17/2023] [Indexed: 09/22/2023] Open
Abstract
Penicillium expansum is the causal agent of post-harvest blue mold in various fruits and serves as a model for understanding fungal pathogenicity and mycotoxin production. The relevance of oxidative stress response in the growth and virulence of P. expansum has been largely unexplored. Here, we identify the transcriptional factor PeAP1 as a regulator of oxidative stress response in P. expansum. Gene expression and protein abundance of PeAP1, as well as its nuclear localization, are specifically induced by H2O2. Deletion of PeAP1 results in increased sensitivity to H2O2, and PeAP1 mutants exhibit a variety of defects in hyphal growth and virulence. PeAP1 prevents the accumulation of both intracellular H2O2 during vegetative growth and host-derived H2O2 during biotrophic growth. Application of an antioxidant glutathione and a NADPH oxidase inhibitor, diphenylene iodonium, to the PeAP1 mutant partially restored fungal growth and virulence. RNA sequencing analysis revealed 144 H2O2-induced PeAP1 target genes, including four antioxidant-related genes, PeGST1, PePrx1, PePrx2, and PeTRX2, that were also demonstrated to be involved in oxidative stress response and/or virulence. Collectively, our results demonstrate the global regulatory role of PeAP1 in response to oxidative stress and provide insights into the critical role of the PeAP1-mediated oxidative stress response to regulate growth and virulence of P. expansum. IMPORTANCE Reactive oxygen species are the core of host plant defense and also play a vital role in the successful invasion of host plants by pathogenic fungi. Despite its importance, the relevance of oxidative stress response in fungal growth and virulence is poorly understood in P. expansum. In this study, we reveal that the transcription factor PeAP1 acts as a central regulator of oxidative stress response in P. expansum and that there is a major link between PeAP1-mediated oxidative stress response and fungal growth and virulence. To explore the underlying mechanisms, we performed comparative transcriptomic studies and identified a number of H2O2-induced PeAP1 target genes, including four novel ones, PePrx1, PePrx2, PeGST1, and PeTRX2, whose functions were linked to PeAP1 and pathogenicity. These findings provide novel insights into the regulation mechanism of PeAP1 on growth and virulence, which might offer promising targets for control of blue mold and patulin contamination.
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Affiliation(s)
- Yong Chen
- State Key Laboratory of Plant Diversity and Specialty Crops, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- China National Botanical Garden, Beijing, China
| | - Yichen Zhang
- State Key Laboratory of Plant Diversity and Specialty Crops, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Dongying Xu
- State Key Laboratory of Plant Diversity and Specialty Crops, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Zhanquan Zhang
- State Key Laboratory of Plant Diversity and Specialty Crops, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- China National Botanical Garden, Beijing, China
| | - Boqiang Li
- State Key Laboratory of Plant Diversity and Specialty Crops, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- China National Botanical Garden, Beijing, China
| | - Shiping Tian
- State Key Laboratory of Plant Diversity and Specialty Crops, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- China National Botanical Garden, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
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Wu JJ, Wu PC, Yago JI, Chung KR. The Regulatory Hub of Siderophore Biosynthesis in the Phytopathogenic Fungus Alternaria alternata. J Fungi (Basel) 2023; 9:jof9040427. [PMID: 37108881 PMCID: PMC10146468 DOI: 10.3390/jof9040427] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 03/22/2023] [Accepted: 03/28/2023] [Indexed: 04/03/2023] Open
Abstract
A GATA zinc finger-containing repressor (AaSreA) suppresses siderophore biosynthesis in the phytopathogenic fungus Alternaria alternata under iron-replete conditions. In this study, targeted gene deletion revealed two bZIP-containing transcription factors (AaHapX and AaAtf1) and three CCAAT-binding proteins (AaHapB, AaHapC, and AaHapE) that positively regulate gene expression in siderophore production. This is a novel phenotype regarding Atf1 and siderophore biosynthesis. Quantitative RT-PCR analyses revealed that only AaHapX and AaSreA were regulated by iron. AaSreA and AaHapX form a transcriptional feedback negative loop to regulate iron acquisition in response to the availability of environmental iron. Under iron-limited conditions, AaAtf1 enhanced the expression of AaNps6, thus playing a positive role in siderophore production. However, under nutrient-rich conditions, AaAtf1 plays a negative role in resistance to sugar-induced osmotic stress, and AaHapX plays a negative role in resistance to salt-induced osmotic stress. Virulence assays performed on detached citrus leaves revealed that AaHapX and AaAtf1 play no role in fungal pathogenicity. However, fungal strains carrying the AaHapB, AaHapC, or AaHapE deletion failed to incite necrotic lesions, likely due to severe growth deficiency. Our results revealed that siderophore biosynthesis and iron homeostasis are regulated by a well-organized network in A. alternata.
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Myxobacterial Outer Membrane β-1,6-Glucanase Induced the Cell Death of Fusarium oxysporum by Destroying the Cell Wall Integrity. Appl Environ Microbiol 2023; 89:e0123622. [PMID: 36602342 PMCID: PMC9888188 DOI: 10.1128/aem.01236-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The β-1,6-glucan is the key linker between mannoproteins in the outermost part of the cell wall and β-1,3-glucan/chitin polysaccharide to maintain the rigid structure of the cell wall. The β-1,6-glucanase GluM, which was purified from the fermentation supernatant of Corallococcus sp. EGB, was able to inhibit the germination of Fusarium oxysporum f. sp. cucumerinum conidia at a minimum concentration of 2.0 U/mL (0.08 μg/mL). The survival rates of GluM-treated conidia and monohyphae were 10.4% and 30.7%, respectively, which were significantly lower than that of β-1,3-glucanase treatment (Zymolyase, 20.0 U/mL; equate to 1.0 mg/mL) (72.9% and 73.9%). In contrast to β-1,3-glucanase treatment, the high-osmolarity glycerol (HOG) pathway of F. oxysporum f. sp. cucumerinum cells was activated after GluM treatment, and the intracellular glycerol content was increased by 2.6-fold. Moreover, the accumulation of reactive oxygen species (ROS) in F. oxysporum f. sp. cucumerinum cells after GluM treatment induced apoptosis, but it was not associated with the increased intracellular glycerol content. Together, the results indicate that β-1,6-glucan is a promising target for the development of novel broad-spectrum antifungal agents. IMPORTANCE Phytopathogenic fungi are the most devastating plant pathogens in agriculture, causing enormous economic losses to global crop production. Biocontrol agents have been promoted as replacements to synthetic chemical pesticides for sustainable agriculture development. Cell wall-degrading enzymes (CWDEs), including chitinases and β-1,3-glucanases, have been considered as important armaments to damage the cell wall. Here, we found that F. oxysporum f. sp. cucumerinum is more sensitive to β-1,6-glucanase GluM treatment (0.08 μg/mL) than β-1,3-glucanase Zymolyase (1.0 mg/mL). The HOG pathway was activated in F. oxysporum f. sp. cucumerinum cells after GluM treatment, and the intracellular glycerol content was significantly increased. Moreover, the decomposition of F. oxysporum f. sp. cucumerinum cell wall by GluM induced the burst of intracellular ROS and apoptosis, which eventually leads to cell death. Therefore, we suggest that the β-1,6-glucan of the fungal cell wall may be a better antifungal target compared to the β-1,3-glucan.
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Choo CYL, Wu PC, Yago JI, Chung KR. The Pex3-mediated peroxisome biogenesis plays a critical role in metabolic biosynthesis, stress response, and pathogenicity in Alternaria alternata. Microbiol Res 2023; 266:127236. [DOI: 10.1016/j.micres.2022.127236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 10/11/2022] [Accepted: 10/11/2022] [Indexed: 11/06/2022]
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Wu P, Choo CYL, Lu H, Wei X, Chen Y, Yago JI, Chung K. Pexophagy is critical for fungal development, stress response, and virulence in Alternaria alternata. MOLECULAR PLANT PATHOLOGY 2022; 23:1538-1554. [PMID: 35810316 PMCID: PMC9452759 DOI: 10.1111/mpp.13247] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 06/16/2022] [Accepted: 06/22/2022] [Indexed: 06/09/2023]
Abstract
Alternaria alternata can resist high levels of reactive oxygen species (ROS). The protective roles of autophagy or autophagy-mediated degradation of peroxisomes (termed pexophagy) against oxidative stress remain unclear. The present study, using transmission electron microscopy and fluorescence microscopy coupled with a GFP-AaAtg8 proteolysis assay and an mCherry tagging assay with peroxisomal targeting tripeptides, demonstrated that hydrogen peroxide (H2 O2 ) and nitrogen depletion induced autophagy and pexophagy. Experimental evidence showed that H2 O2 triggered autophagy and the translocation of peroxisomes into the vacuoles. Mutational inactivation of the AaAtg8 gene in A. alternata led to autophagy impairment, resulting in the accumulation of peroxisomes, increased ROS sensitivity, and decreased virulence. Compared to the wild type, ΔAaAtg8 failed to detoxify ROS effectively, leading to ROS accumulation. Deleting AaAtg8 down-regulated the expression of genes encoding an NADPH oxidase and a Yap1 transcription factor, both involved in ROS resistance. Deleting AaAtg8 affected the development of conidia and appressorium-like structures. Deleting AaAtg8 also compromised the integrity of the cell wall. Reintroduction of a functional copy of AaAtg8 in the mutant completely restored all defective phenotypes. Although ΔAaAtg8 produced wild-type toxin levels in axenic culture, the mutant induced a lower level of H2 O2 and smaller necrotic lesions on citrus leaves. In addition to H2 O2 , nitrogen starvation triggered peroxisome turnover. We concluded that ΔAaAtg8 failed to degrade peroxisomes effectively, leading to the accumulation of peroxisomes and the reduction of the stress response. Autophagy-mediated peroxisome turnover could increase cell adaptability and survival under oxidative stress and starvation conditions.
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Affiliation(s)
- Pei‐Ching Wu
- Department of Plant Pathology, College of Agriculture and Natural ResourcesNational Chung Hsing UniversityTaichungTaiwan
| | - Celine Yen Ling Choo
- Department of Plant Pathology, College of Agriculture and Natural ResourcesNational Chung Hsing UniversityTaichungTaiwan
| | - Hsin‐Yu Lu
- Department of Plant Pathology, College of Agriculture and Natural ResourcesNational Chung Hsing UniversityTaichungTaiwan
| | - Xian‐Yong Wei
- Department of Plant Pathology, College of Agriculture and Natural ResourcesNational Chung Hsing UniversityTaichungTaiwan
| | - Yu‐Kun Chen
- Department of Plant Pathology, College of Agriculture and Natural ResourcesNational Chung Hsing UniversityTaichungTaiwan
| | - Jonar I. Yago
- Plant Science Department, College of AgricultureNueva Vizcaya State UniversityBayombongPhilippines
| | - Kuang‐Ren Chung
- Department of Plant Pathology, College of Agriculture and Natural ResourcesNational Chung Hsing UniversityTaichungTaiwan
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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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Lu HY, Huang YL, Wu PC, Wei XY, Yago JI, Chung KR. A zinc finger suppressor involved in stress resistance, cell wall integrity, conidiogenesis, and autophagy in the necrotrophic fungal pathogen Alternaria alternata. Microbiol Res 2022; 263:127106. [PMID: 35839700 DOI: 10.1016/j.micres.2022.127106] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 05/18/2022] [Accepted: 06/22/2022] [Indexed: 10/17/2022]
Abstract
The tangerine pathotype of Alternaria alternata can withstand high-level reactive oxygen species (ROS). By analyzing loss- and gain-of-function mutants, this study demonstrated that a Cys2His2 zinc finger-containing transcription regulator, A. alternata Stress Response Regulator 1 (AaSRR1), plays a negative role in resistance to peroxides and singlet-oxygen-generating compounds. AaSRR1 plays no role in cellular susceptibility or resistance to superoxide-producing compounds. AaSRR1 also negatively regulates conidiogenesis, maintenance of cell wall and membrane integrities, and chitin biosynthesis. Some wild-type hyphae displayed necrosis after exposure to 30 mM H2O2, whereas AaSRR1 deficient mutant (ΔAaSRR1) hyphae had visible granules and vacuoles. sGFP-AaATG8 proteolysis assays revealed that H2O2 and starvation could trigger autophagy formation in both wild type and ΔAaSRR1. Autophagy occurred at higher rates in ΔAaSRR1 than wild type under both conditions, particularly after H2O2 treatments, indicating that autophagy might contribute to ROS resistance. Upon exposure to H2O2 or under starvation, AaSRR1 was translocated into the nucleus, even though the expression of AaSRR1 was decreased. AaSRR1 is required for vegetative growth but is dispensable for fungal virulence as assayed on detached calamondin leaves. AaSRR1 suppressed the expression of the gene encoding a HOG1 mitogen-activated protein (MAP) kinase implicated in ROS resistance. Mutation of AaSRR1 increased catalase activity but decreased superoxide dismutase activity, leading to fewer ROS accumulation in the cytosol. Nevertheless, our results indicated that AaSRR1 is a transcription suppressor for ROS resistance. This study also revealed tradeoffs between stress responses and hyphal growth in A. alternata.
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Affiliation(s)
- Hsin-Yu Lu
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung Hsing University, Taichung 40227, Taiwan
| | - Yu-Ling Huang
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung Hsing University, Taichung 40227, Taiwan
| | - Pei-Ching Wu
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung Hsing University, Taichung 40227, Taiwan.
| | - Xian-Yong Wei
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung Hsing University, Taichung 40227, Taiwan
| | - Jonar I Yago
- Plant Science Department, College of Agriculture, Nueva Vizcaya State University, Bayombong, Nueva Vizcaya 3700, Philippines
| | - Kuang-Ren Chung
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung Hsing University, Taichung 40227, Taiwan.
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Zhao K, Liu L, Huang S. Genome-Wide Identification and Functional Analysis of the bZIP Transcription Factor Family in Rice Bakanae Disease Pathogen, Fusarium fujikuroi. Int J Mol Sci 2022; 23:ijms23126658. [PMID: 35743103 PMCID: PMC9223689 DOI: 10.3390/ijms23126658] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 06/07/2022] [Accepted: 06/11/2022] [Indexed: 12/10/2022] Open
Abstract
Fungal basic leucine zipper (bZIP) proteins play a vital role in biological processes such as growth, biotic/abiotic stress responses, nutrient utilization, and invasion. In this study, genome-wide identification of bZIP genes in the fungus Fusarium fujikuroi, the pathogen of bakanae disease, was carried out. Forty-four genes encoding bZIP transcription factors (TFs) from the genome of F. fujikuroi (FfbZIP) were identified and functionally characterized. Structures, domains, and phylogenetic relationships of the sequences were analyzed by bioinformatic approaches. Based on the phylogenetic relationships with the FfbZIP proteins of eight other fungi, the bZIP genes can be divided into six groups (A–F). The additional conserved motifs have been identified and their possible functions were predicted. To analyze functions of the bZIP genes, 11 FfbZIPs were selected according to different motifs they contained and were knocked out by genetic recombination. Results of the characteristic studies revealed that these FfbZIPs were involved in oxygen stress, osmotic stress, cell wall selection pressure, cellulose utilization, cell wall penetration, and pathogenicity. In conclusion, this study enhanced understandings of the evolution and regulatory mechanism of the FfbZIPs in fungal growth, abiotic/biotic stress resistance, and pathogenicity, which could be the reference for other fungal bZIP studies.
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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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14
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Ma H, Li L, Gai Y, Zhang X, Chen Y, Zhuo X, Cao Y, Jiao C, Gmitter FG, Li H. Histone Acetyltransferases and Deacetylases Are Required for Virulence, Conidiation, DNA Damage Repair, and Multiple Stresses Resistance of Alternaria alternata. Front Microbiol 2021; 12:783633. [PMID: 34880849 PMCID: PMC8645686 DOI: 10.3389/fmicb.2021.783633] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Accepted: 11/02/2021] [Indexed: 01/16/2023] Open
Abstract
Histone acetylation, which is critical for transcriptional regulation and various biological processes in eukaryotes, is a reversible dynamic process regulated by HATs and HDACs. This study determined the function of 6 histone acetyltransferases (HATs) (Gcn5, RTT109, Elp3, Sas3, Sas2, Nat3) and 6 histone deacetylases (HDACs) (Hos2, Rpd3, Hda1, Hos3, Hst2, Sir2) in the phytopathogenic fungus Alternaria alternata by analyzing targeted gene deletion mutants. Our data provide evidence that HATs and HDACs are both required for mycelium growth, cell development and pathogenicity as many gene deletion mutants (ΔGcn5, ΔRTT109, ΔElp3, ΔSas3, ΔNat3, ΔHos2, and ΔRpd3) displayed reduced growth, conidiation or virulence at varying degrees. In addition, HATs and HDACs are involved in the resistance to multiple stresses such as oxidative stress (Sas3, Gcn5, Elp3, RTT109, Hos2), osmotic stress (Sas3, Gcn5, RTT109, Hos2), cell wall-targeting agents (Sas3, Gcn5, Hos2), and fungicide (Gcn5, Hos2). ΔGcn5, ΔSas3, and ΔHos2 displayed severe growth defects on sole carbon source medium suggesting a vital role of HATs and HDACs in carbon source utilization. More SNPs were generated in ΔGcn5 in comparison to wild-type when they were exposed to ultraviolet ray. Moreover, ΔRTT109, ΔGcn5, and ΔHos2 showed severe defects in resistance to DNA-damaging agents, indicating the critical role of HATs and HDACs in DNA damage repair. These phenotypes correlated well with the differentially expressed genes in ΔGcn5 and ΔHos2 that are essential for carbon sources metabolism, DNA damage repair, ROS detoxification, and asexual development. Furthermore, Gcn5 is required for the acetylation of H3K4. Overall, our study provides genetic evidence to define the central role of HATs and HDACs in the pathological and biological functions of A. alternata.
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Affiliation(s)
- Haijie Ma
- Collaborative Innovation Center for Efficient and Green Production of Agriculture in Mountainous Areas of Zhejiang Province, College of Horticulture Science, Zhejiang A&F University, Hangzhou, China.,Key Lab of Molecular Biology of Crop Pathogens and Insects, Ministry of Agriculture, Institute of Biotechnology, Zhejiang University, Hangzhou, China.,Citrus Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL, United States
| | - Lei Li
- Key Lab of Molecular Biology of Crop Pathogens and Insects, Ministry of Agriculture, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Yunpeng Gai
- Key Lab of Molecular Biology of Crop Pathogens and Insects, Ministry of Agriculture, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Xiaoyan Zhang
- Key Lab of Molecular Biology of Crop Pathogens and Insects, Ministry of Agriculture, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Yanan Chen
- Key Lab of Molecular Biology of Crop Pathogens and Insects, Ministry of Agriculture, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Xiaokang Zhuo
- Citrus Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL, United States
| | - Yingzi Cao
- Key Lab of Molecular Biology of Crop Pathogens and Insects, Ministry of Agriculture, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Chen Jiao
- Key Lab of Molecular Biology of Crop Pathogens and Insects, Ministry of Agriculture, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Fred G Gmitter
- Citrus Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL, United States
| | - Hongye Li
- Key Lab of Molecular Biology of Crop Pathogens and Insects, Ministry of Agriculture, Institute of Biotechnology, Zhejiang University, Hangzhou, China
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15
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Gai Y, Li L, Liu B, Ma H, Chen Y, Zheng F, Sun X, Wang M, Jiao C, Li H. Distinct and essential roles of bZIP transcription factors in the stress response and pathogenesis in Alternaria alternata. Microbiol Res 2021; 256:126915. [PMID: 34953292 DOI: 10.1016/j.micres.2021.126915] [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: 03/30/2021] [Revised: 09/05/2021] [Accepted: 10/15/2021] [Indexed: 12/27/2022]
Abstract
The ability to cope with environmental abiotic stress and biotic stress is crucial for the survival of plants and microorganisms, which enable them to occupy multiple niches in the environment. Previous studies have shown that transcription factors play crucial roles in regulating various biological processes including multiple stress tolerance and response in eukaryotes. This work identified multiple critical transcription factor genes, metabolic pathways and gene ontology (GO) terms related to abiotic stress response were broadly activated by analyzing the transcriptome of phytopathogenic fungus Alternaria alternata under metal ions stresses, oxidative stress, salt stresses, and host-pathogen interaction. We investigated the biological functions and regulatory roles of the bZIP transcriptional factor (TF) genes in the phytopathogenic fungus A.alternata by analyzing targeted gene disrupted mutants. Morphological analysis provides evidence that the bZIP transcription factors (Gcn4, MeaB, Atf1, the ER stress regulator Hac1, and the all development altered-1 gene Ada1) are required for morphogenesis as the colony morphology of these gene deletion mutants was significantly different from that of the wild-type. In addition, bZIPs are involved in the resistance to multiple stresses such as oxidative stress (Ada1, Yap1, MetR) and virulence (Hac1, MetR, Yap1, Ada1) at varying degrees. Transcriptome data demonstrated that the inactivation of bZIPs (Hac1, Atf1, Ada1 and Yap1) significantly affected many genes in multiple critical metabolism pathways and gene ontology (GO) terms. Moreover,the ΔHac1 mutants displayed reduced aerial hypha and are hypersensitivity to endoplasmic reticulum disruptors such as tunicamycin and dithiothreitol. Transcriptome analysis showed that inactivation of Hac1 significantly affected the proteasome process and its downstream unfolded protein binding, indicating that Hac1 participates in the endoplasmic reticulum stress response through the conserved unfolded protein response. Taken together, our findings reveal that bZIP transcription factors function as key regulators of fungal morphogenesis, abiotic stress response and pathogenesis, and expand our understanding of how microbial pathogens utilize these genes to deal with environmental stresses and achieve successful infection in the host plant.
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Affiliation(s)
- Yunpeng Gai
- Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China; School of Grassland Science, Beijing Forestry University, Beijing, 100083, China.
| | - Lei Li
- Department of Plant Pathology, South China Agricultural University, Guangzhou 510640, China
| | - Bing Liu
- Yangzhou Polytechnic College, Yangzhou 225009, China
| | - Haijie Ma
- School of Agriculture and Food Sciences, Zhejiang Agriculture & Forestry University, Hangzhou, 311300, China
| | - Yanan Chen
- Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Fang Zheng
- Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Xuepeng Sun
- School of Agriculture and Food Sciences, Zhejiang Agriculture & Forestry University, Hangzhou, 311300, China
| | - Mingshuang Wang
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, 311121, China
| | - Chen Jiao
- Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Hongye Li
- Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China.
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16
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Zhang H, Shen W, Zhang D, Shen X, Wang F, Hsiang T, Liu J, Li G. The bZIP Transcription Factor LtAP1 Modulates Oxidative Stress Tolerance and Virulence in the Peach Gummosis Fungus Lasiodiplodia theobromae. Front Microbiol 2021; 12:741842. [PMID: 34630367 PMCID: PMC8495313 DOI: 10.3389/fmicb.2021.741842] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 08/25/2021] [Indexed: 12/02/2022] Open
Abstract
Lasiodiplodia theobromae is one of the primary causal agents in peach gummosis disease, leading to enormous losses in peach production. In our previous study, a redox-related gene, LtAP1, from the fungus was significantly upregulated in peach shoots throughout infection. Here, we characterized LtAP1, a basic leucine zipper transcription factor, during peach gummosis progression using the CRISPR-Cas9 system and homologous recombination. The results showed that LtAP1-deletion mutant had slower vegetative growth and increased sensitivity to several oxidative and nitrosative stress agents. LtAP1 was highly induced by exogenous oxidants treatment in the L. theobromae wild-type strain. In a pathogenicity test, the deletion mutant showed decreased virulence (reduced size of necrotic lesions, less gum release, and decreased pathogen biomass) on infected peach shoots compared to the wild-type strain. The mutant showed severely reduced transcription levels of genes related to glutaredoxin and thioredoxin in L. theobroame under oxidative stress or during infection, indicating an attenuated capacity for reactive oxygen species (ROS) detoxification. When shoots were treated with an NADPH oxidase inhibitor, the pathogenicity of the mutant was partially restored. Moreover, ROS production and plant defense response were strongly activated in peach shoots infected by the mutant. These results highlight the crucial role of LtAP1 in the oxidative stress response, and further that it acts as an important virulence factor through modulating the fungal ROS-detoxification system and the plant defense response.
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Affiliation(s)
- He Zhang
- Key Laboratory of Horticultural Plant Biology-Ministry of Education, College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, China.,Haikou Experimental Station, Chinese Academy of Tropical Agricultural Sciences, Haikou, China
| | - Wanqi Shen
- Key Laboratory of Horticultural Plant Biology-Ministry of Education, College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, China
| | - Dongmei Zhang
- Key Laboratory of Horticultural Plant Biology-Ministry of Education, College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, China
| | - Xingyi Shen
- Key Laboratory of Horticultural Plant Biology-Ministry of Education, College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, China
| | - Fan Wang
- Jiangxi Oil-tea Camellia, Jiujiang University, Jiujiang, China
| | - Tom Hsiang
- School of Environmental Sciences, University of Guelph, Guelph, ON, Canada
| | - Junwei Liu
- Key Laboratory of Horticultural Plant Biology-Ministry of Education, College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, China
| | - Guohuai Li
- Key Laboratory of Horticultural Plant Biology-Ministry of Education, College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, China
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17
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The NADPH Oxidase A of Verticillium dahliae Is Essential for Pathogenicity, Normal Development, and Stress Tolerance, and It Interacts with Yap1 to Regulate Redox Homeostasis. J Fungi (Basel) 2021; 7:jof7090740. [PMID: 34575778 PMCID: PMC8468606 DOI: 10.3390/jof7090740] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 09/03/2021] [Accepted: 09/07/2021] [Indexed: 12/23/2022] Open
Abstract
Maintenance of redox homeostasis is vital for aerobic organisms and particularly relevant to plant pathogens. A balance is required between their endogenous ROS production, which is important for their development and pathogenicity, and host-derived oxidative stress. Endogenous ROS in fungi are generated by membrane-bound NADPH oxidase (NOX) complexes and the mitochondrial respiratory chain, while transcription factor Yap1 is a major regulator of the antioxidant response. Here, we investigated the roles of NoxA and Yap1 in fundamental biological processes of the important plant pathogen Verticillium dahliae. Deletion of noxA impaired growth and morphogenesis, compromised formation of hyphopodia, diminished penetration ability and pathogenicity, increased sensitivity against antifungal agents, and dysregulated expression of antioxidant genes. On the other hand, deletion of yap1 resulted in defects in conidial and microsclerotia formation, increased sensitivity against oxidative stress, and down-regulated antioxidant genes. Localized accumulation of ROS was observed before conidial fusion and during the heterokaryon incompatibility reaction upon nonself fusion. The frequency of inviable fusions was not affected by the deletion of Yap1. Analysis of a double knockout mutant revealed an epistatic relationship between noxA and yap1. Our results collectively reveal instrumental roles of NoxA and ROS homeostasis in the biology of V. dahliae.
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18
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Zhong Z, McDonald BA, Palma-Guerrero J. Tolerance to oxidative stress is associated with both oxidative stress response and inherent growth in a fungal wheat pathogen. Genetics 2021; 217:6029569. [PMID: 33724407 DOI: 10.1093/genetics/iyaa022] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 11/23/2020] [Indexed: 01/25/2023] Open
Abstract
Reactive oxygen species are toxic byproducts of aerobic respiration that are also important in mediating a diversity of cellular functions. Reactive oxygen species form an important component of plant defenses to inhibit microbial pathogens during pathogen-plant interactions. Tolerance to oxidative stress is likely to make a significant contribution to the viability and pathogenicity of plant pathogens, but the complex network of oxidative stress responses hinders identification of the genes contributing to this trait. Here, we employed a forward genetic approach to investigate the genetic architecture of oxidative stress tolerance in the fungal wheat pathogen Zymoseptoria tritici. We used quantitative trait locus (QTL) mapping of growth and melanization under axenic conditions in two cross-populations to identify genomic regions associated with tolerance to oxidative stress. We found that QTLs associated with growth under oxidative stress as well as inherent growth can affect oxidative stress tolerance, and we identified two uncharacterized genes in a major QTL associated with this trait. Our data suggest that melanization does not affect tolerance to oxidative stress, which differs from what was found for animal pathogens. This study provides a whole-genome perspective on the genetic basis of oxidative stress tolerance in a plant pathogen.
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Affiliation(s)
- Ziming Zhong
- Plant Pathology Group, Institute of Integrative Biology, ETH Zurich, 8092 Zürich, Switzerland
| | - Bruce A McDonald
- Plant Pathology Group, Institute of Integrative Biology, ETH Zurich, 8092 Zürich, Switzerland
| | - Javier Palma-Guerrero
- Plant Pathology Group, Institute of Integrative Biology, ETH Zurich, 8092 Zürich, Switzerland.,Department of Biointeractions and Crop Protection, Rothamsted Research, AL5 2JQ Harpenden, UK
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19
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Zhang X, Zong Y, Gong D, Yu L, Sionov E, Bi Y, Prusky D. NADPH Oxidase Regulates the Growth and Pathogenicity of Penicillium expansum. FRONTIERS IN PLANT SCIENCE 2021; 12:696210. [PMID: 34456938 PMCID: PMC8387719 DOI: 10.3389/fpls.2021.696210] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Accepted: 07/19/2021] [Indexed: 05/31/2023]
Abstract
The occurrence of reactive oxygen species (ROS) during the colonization of necrotrophic pathogens attacking fruit is critical during the attack, but its importance in Penicillium expansum remains unclear. This study aimed to determine the regulatory effects of NADPH oxidase (Nox) genes on the growth and pathogenicity of P. expansum in apple fruits. Deletion mutants of ΔPeNoxA, ΔPeNoxR, and ΔPeRacA genes were constructed to determine the contribution to the colonization process. The ΔPeRacA strain had a significant effect on the reduction of growth and pathogenicity, the ΔPeNoxA strain negatively regulated the growth and development of P. expansum and did not show any significant effect on the pathogenicity, and the ΔPeNoxR strain showed no effect on the growth or pathogenicity of P. expansum in the apple fruits. However, analysis of the content of O2 - and H2O2 in the mycelium of all the Nox mutants showed a significant reduction, confirming the functionality of Nox mutations. Growth under stress conditions in the presence of Congo red, sodium lauryl sulfate, and H2O2 showed a negative effect on the radial growth of ΔPeNoxA, but a positive effect on radial growth reduction by ΔPeNoxR and ΔPeRacA mutants was shown. Interestingly, the host antioxidant activity levels of superoxide dismutase (SOD) andcatalase (CAT) in the fruits after inoculation with ΔPeNoxA, ΔPeNoxR, and ΔPeRacA mutants declined, suggesting reduced ROS accumulation in the colonized region. These results suggest that PeNoxA, PeNoxR, and PeRacA differentially regulate the growth and pathogenicity of P. expansum by producing ROS, and that PeRacA showed the strongest regulatory effect.
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Affiliation(s)
- Xuemei Zhang
- College of Food Science and Engineering, Gansu Agricultural University, Lanzhou, China
| | - Yuanyuan Zong
- College of Food Science and Engineering, Gansu Agricultural University, Lanzhou, China
| | - Di Gong
- College of Food Science and Engineering, Gansu Agricultural University, Lanzhou, China
| | - Lirong Yu
- College of Food Science and Engineering, Gansu Agricultural University, Lanzhou, China
| | - Edward Sionov
- Department of Postharvest Science of Fresh Produce, Agricultural Research Organization, Volcani Center, Rishon LeZion, Israel
| | - Yang Bi
- College of Food Science and Engineering, Gansu Agricultural University, Lanzhou, China
| | - Dov Prusky
- College of Food Science and Engineering, Gansu Agricultural University, Lanzhou, China
- Department of Postharvest Science of Fresh Produce, Agricultural Research Organization, Volcani Center, Rishon LeZion, Israel
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20
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John E, Singh KB, Oliver RP, Tan K. Transcription factor control of virulence in phytopathogenic fungi. MOLECULAR PLANT PATHOLOGY 2021; 22:858-881. [PMID: 33973705 PMCID: PMC8232033 DOI: 10.1111/mpp.13056] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 03/02/2021] [Accepted: 03/04/2021] [Indexed: 05/12/2023]
Abstract
Plant-pathogenic fungi are a significant threat to economic and food security worldwide. Novel protection strategies are required and therefore it is critical we understand the mechanisms by which these pathogens cause disease. Virulence factors and pathogenicity genes have been identified, but in many cases their roles remain elusive. It is becoming increasingly clear that gene regulation is vital to enable plant infection and transcription factors play an essential role. Efforts to determine their regulatory functions in plant-pathogenic fungi have expanded since the annotation of fungal genomes revealed the ubiquity of transcription factors from a broad range of families. This review establishes the significance of transcription factors as regulatory elements in plant-pathogenic fungi and provides a systematic overview of those that have been functionally characterized. Detailed analysis is provided on regulators from well-characterized families controlling various aspects of fungal metabolism, development, stress tolerance, and the production of virulence factors such as effectors and secondary metabolites. This covers conserved transcription factors with either specialized or nonspecialized roles, as well as recently identified regulators targeting key virulence pathways. Fundamental knowledge of transcription factor regulation in plant-pathogenic fungi provides avenues to identify novel virulence factors and improve our understanding of the regulatory networks linked to pathogen evolution, while transcription factors can themselves be specifically targeted for disease control. Areas requiring further insight regarding the molecular mechanisms and/or specific classes of transcription factors are identified, and direction for future investigation is presented.
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Affiliation(s)
- Evan John
- Centre for Crop and Disease ManagementCurtin UniversityBentleyWestern AustraliaAustralia
- School of Molecular and Life SciencesCurtin UniversityBentleyWestern AustraliaAustralia
| | - Karam B. Singh
- Agriculture and FoodCommonwealth Scientific and Industrial Research OrganisationFloreatWestern AustraliaAustralia
| | - Richard P. Oliver
- School of Molecular and Life SciencesCurtin UniversityBentleyWestern AustraliaAustralia
| | - Kar‐Chun Tan
- Centre for Crop and Disease ManagementCurtin UniversityBentleyWestern AustraliaAustralia
- School of Molecular and Life SciencesCurtin UniversityBentleyWestern AustraliaAustralia
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21
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Wu PC, Chen YK, Yago JI, Chung KR. Peroxisomes Implicated in the Biosynthesis of Siderophores and Biotin, Cell Wall Integrity, Autophagy, and Response to Hydrogen Peroxide in the Citrus Pathogenic Fungus Alternaria alternata. Front Microbiol 2021; 12:645792. [PMID: 34262533 PMCID: PMC8273606 DOI: 10.3389/fmicb.2021.645792] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Accepted: 05/25/2021] [Indexed: 11/13/2022] Open
Abstract
Little is known about the roles of peroxisomes in the necrotrophic fungal plant pathogens. In the present study, a Pex6 gene encoding an ATPase-associated protein was characterized by analysis of functional mutations in the tangerine pathotype of Alternaria alternata, which produces a host-selective toxin. Peroxisomes were observed in fungal cells by expressing a mCherry fluorescent protein tagging with conserved tripeptides serine-lysing-leucine and transmission electron microscopy. The results indicated that Pex6 plays no roles in peroxisomal biogenesis but impacts protein import into peroxisomes. The number of peroxisomes was affected by nutritional conditions and H2O2, and their degradation was mediated by an autophagy-related machinery termed pexophagy. Pex6 was shown to be required for the formation of Woronin bodies, the biosynthesis of biotin, siderophores, and toxin, the uptake and accumulation of H2O2, growth, and virulence, as well as the Slt2 MAP kinase-mediated maintenance of cell wall integrity. Adding biotin, oleate, and iron in combination fully restored the growth of the pex6-deficient mutant (Δpex6), but failed to restore Δpex6 virulence to citrus. Adding purified toxin could only partially restore Δpex6 virulence even in the presence of biotin, oleate, and iron. Sensitivity assays revealed that Pex6 plays no roles in resistance to H2O2 and superoxide, but plays a negative role in resistance to 2-chloro-5-hydroxypyridine (a hydroxyl radical-generating compound), eosin Y and rose Bengal (singlet oxygen-generating compounds), and 2,3,5-triiodobenzoic acid (an auxin transport inhibitor). The diverse functions of Pex6 underscore the importance of peroxisomes in physiology, pathogenesis, and development in A. alternata.
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Affiliation(s)
- Pei-Ching Wu
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung Hsing University, Taichung, Taiwan
| | - Yu-Kun Chen
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung Hsing University, Taichung, Taiwan
| | - Jonar I Yago
- Plant Science Department, College of Agriculture, Nueva Vizcaya State University, Bayombong, Philippines
| | - Kuang-Ren Chung
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung Hsing University, Taichung, Taiwan
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22
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Singh Y, Nair AM, Verma PK. Surviving the odds: From perception to survival of fungal phytopathogens under host-generated oxidative burst. PLANT COMMUNICATIONS 2021; 2:100142. [PMID: 34027389 PMCID: PMC8132124 DOI: 10.1016/j.xplc.2021.100142] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 12/04/2020] [Accepted: 01/01/2021] [Indexed: 05/04/2023]
Abstract
Fungal phytopathogens pose a serious threat to global crop production. Only a handful of strategies are available to combat these fungal infections, and the increasing incidence of fungicide resistance is making the situation worse. Hence, the molecular understanding of plant-fungus interactions remains a primary focus of plant pathology. One of the hallmarks of host-pathogen interactions is the overproduction of reactive oxygen species (ROS) as a plant defense mechanism, collectively termed the oxidative burst. In general, high accumulation of ROS restricts the growth of pathogenic organisms by causing localized cell death around the site of infection. To survive the oxidative burst and achieve successful host colonization, fungal phytopathogens employ intricate mechanisms for ROS perception, ROS neutralization, and protection from ROS-mediated damage. Together, these countermeasures maintain the physiological redox homeostasis that is essential for cell viability. In addition to intracellular antioxidant systems, phytopathogenic fungi also deploy interesting effector-mediated mechanisms for extracellular ROS modulation. This aspect of plant-pathogen interactions is significantly under-studied and provides enormous scope for future research. These adaptive responses, broadly categorized into "escape" and "exploitation" mechanisms, are poorly understood. In this review, we discuss the oxidative stress response of filamentous fungi, their perception signaling, and recent insights that provide a comprehensive understanding of the distinct survival mechanisms of fungal pathogens in response to the host-generated oxidative burst.
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Affiliation(s)
- Yeshveer Singh
- Plant Immunity Laboratory, National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi 110067, India
| | - Athira Mohandas Nair
- Plant Immunity Laboratory, National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi 110067, India
| | - Praveen Kumar Verma
- Plant Immunity Laboratory, National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi 110067, India
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
- Corresponding author
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23
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Khalid AR, Zhang S, Luo X, Shaheen H, Majeed A, Maqbool M, Zahid N, Rahim J, Ren M, Qiu D. Functional Analysis of Autophagy-Related Gene ATG12 in Potato Dry Rot Fungus Fusarium oxysporum. Int J Mol Sci 2021; 22:ijms22094932. [PMID: 34066497 PMCID: PMC8125257 DOI: 10.3390/ijms22094932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 04/28/2021] [Accepted: 04/28/2021] [Indexed: 11/16/2022] Open
Abstract
Autophagy is an intracellular process in all eukaryotes which is responsible for the degradation of cytoplasmic constituents, recycling of organelles, and recycling of proteins. It is an important cellular process responsible for the effective virulence of several pathogenic plant fungal strains, having critical impacts on important crop plants including potatoes. However, the detailed physiological mechanisms of autophagy involved in the infection biology of soil-borne pathogens in the potato crop needs to be investigated further. In this study, the autophagy-related gene, FoATG12, in potato dry rot fungus Fusarium oxysporum was investigated by means of target gene replacement and overexpression. The deletion mutant ∆FoATG12 showed reduction in conidial formation and exhibited impaired aerial hyphae. The FoATG12 affected the expression of genes involved in pathogenicity and vegetative growth, as well as on morphology features of the colony under stressors. It was found that the disease symptoms were delayed upon being inoculated by the deletion mutant of FoATG12 compared to the wild-type (WT) and overexpression (OE), while the deletion mutant showed the disease symptoms on tomato plants. The results confirmed the significant role of the autophagy-related ATG12 gene in the production of aerial hyphae and the effective virulence of F. oxysporum in the potato crop. The current findings provid an enhanced gene-level understanding of the autophagy-related virulence of F. oxysporum, which could be helpful in pathogen control research and could have vital impacts on the potato crop.
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Affiliation(s)
- A. Rehman Khalid
- School of Life Sciences, Chongqing University, Chongqing 401331, China; (X.L.); (M.R.)
- Department of Plant Pathology, University of Poonch Rawalakot, Azad Jammu and Kashmir 12350, Pakistan
- Correspondence: (A.R.K.); (D.Q.)
| | - Shumin Zhang
- School of Preclinical Medicine, North Sichuan Medical College, Nanchong 637000, China;
| | - Xiumei Luo
- School of Life Sciences, Chongqing University, Chongqing 401331, China; (X.L.); (M.R.)
| | - Hamayun Shaheen
- Department of Botany, University of Azad Jammu and Kashmir, Muzaffarabad 13100, Pakistan;
| | - Afshan Majeed
- Department of Soil and Environmental Sciences, University of Poonch Rawalakot, Azad Jammu and Kashmir 12350, Pakistan;
| | - Mehdi Maqbool
- Department of Horticulture, University of Poonch Rawalakot, Azad Jammu and Kashmir 12350, Pakistan; (M.M.); (N.Z.)
| | - Noosheen Zahid
- Department of Horticulture, University of Poonch Rawalakot, Azad Jammu and Kashmir 12350, Pakistan; (M.M.); (N.Z.)
| | - Junaid Rahim
- Department of Entomology, University of Poonch Rawalakot, Azad Jammu and Kashmir 12350, Pakistan;
| | - Maozhi Ren
- School of Life Sciences, Chongqing University, Chongqing 401331, China; (X.L.); (M.R.)
| | - Dan Qiu
- School of Life Sciences, Chongqing University, Chongqing 401331, China; (X.L.); (M.R.)
- Correspondence: (A.R.K.); (D.Q.)
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Feng H, Xu M, Gao Y, Liang J, Guo F, Guo Y, Huang L. Vm-milR37 contributes to pathogenicity by regulating glutathione peroxidase gene VmGP in Valsa mali. MOLECULAR PLANT PATHOLOGY 2021; 22:243-254. [PMID: 33278058 PMCID: PMC7814965 DOI: 10.1111/mpp.13023] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Revised: 10/18/2020] [Accepted: 11/05/2020] [Indexed: 05/22/2023]
Abstract
MicroRNAs play important roles in various biological processes by regulating their corresponding target genes. However, the function and regulatory mechanism of fungal microRNA-like RNAs (milRNAs) are still largely unknown. In this study, a milRNA (Vm-milR37) was isolated and identified from Valsa mali, which causes the most serious disease on the trunk of apple trees in China. Based on the results of deep sequencing and quantitative reverse transcription PCR, Vm-milR37 was found to be expressed in the mycelium, while it was not expressed during the V. mali infection process. Overexpression of Vm-milR37 did not affect vegetative growth, but significantly decreased pathogenicity. Based on degradome sequencing, the target of Vm-milR37 was identified as VmGP, a glutathione peroxidase. The expression of Vm-milR37 and VmGP showed a divergent trend in V. mali-apple interaction samples and Vm-milR37 overexpression transformants. The expression of VmGP could be suppressed significantly by Vm-milR37 when coexpressed in tobacco leaves. Deletion of VmGP showed significantly reduced pathogenicity compared with the wild type. VmGP deletion mutants showed more sensitivity to hydrogen peroxide. Apple leaves inoculated with Vm-milR37 overexpression transformants and VmGP deletion mutant displayed increased accumulation of reactive oxygen species compared with the wild type. Thus, Vm-milR37 plays a critical role in pathogenicity by regulating VmGP, which contributes to the oxidative stress response during V. mali infection. These results provide important evidence to define the roles of milRNAs and their corresponding target genes in pathogenicity.
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Affiliation(s)
- Hao Feng
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant ProtectionNorthwest A&F UniversityYanglingChina
| | - Ming Xu
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant ProtectionNorthwest A&F UniversityYanglingChina
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life SciencesNorthwest A&F UniversityYanglingChina
| | - Yuqi Gao
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant ProtectionNorthwest A&F UniversityYanglingChina
| | - Jiahao Liang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant ProtectionNorthwest A&F UniversityYanglingChina
| | - Feiran Guo
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant ProtectionNorthwest A&F UniversityYanglingChina
| | - Yan Guo
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant ProtectionNorthwest A&F UniversityYanglingChina
| | - Lili Huang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant ProtectionNorthwest A&F UniversityYanglingChina
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The critical role of MetR/ MetB/ MetC/ MetX in cysteine and methionine metabolism, fungal development and virulence of Alternaria alternata. Appl Environ Microbiol 2021; 87:AEM.01911-20. [PMID: 33277273 PMCID: PMC7851696 DOI: 10.1128/aem.01911-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Methionine is a unique sulfur-containing amino acid, which plays an important role in biological protein synthesis and various cellular processes. Here, we characterized the biological functions of AaMetB, AaMetC, and AaMetX in the tangerine pathotype of Alternaria alternata Morphological analysis showed that the mutants lacking AaMetB, AaMetC, or AaMetX resulted in less aerial hypha and fewer conidia in artificial media. Pathogenicity analysis showed that AaMetB, AaMetC, and AaMetX are required for full virulence. The defects in vegetative growth, conidiation and virulence of ΔMetB, ΔMetC, and ΔMetX can be restored by exogenous methionine and homocysteine, indicating that AaMetB, AaMetC, and AaMetX are required for methionine biosynthesis. However, exogenous cysteine only restored the growth and virulence defects of ΔMetR but not ΔMetB/C/X, suggesting that AaMetR is essential for cysteine biosynthesis. Oxidant sensitivity assay showed that only ΔMetR is sensitive to H2O2 and many ROS-generating compounds, indicating that AaMetR is essential for oxidative tolerance. Interestingly, fungicides indoor bioassays showed that only the ΔMetR mutants are susceptive to chlorothalonil, a fungicide that could bind to the cysteine of glyceraldehyde-3-phosphate dehydrogenase. Comparative transcriptome analysis showed that the inactivation of MetB, MetC, MetX, or MetR significantly affected the expression of methionine metabolism-related genes. Moreover, the inactivation of AaMetR significantly affected the expression of many genes related to glutathione metabolism, which is essential for ROS tolerance. Taken together, our study provides genetic evidence to define the critical roles of AaMetB, AaMetC, AaMetX, and AaMetR in cysteine and methionine metabolism, fungal development and virulence of Alternaria alternata IMPORTANCE The transcription factor METR regulating methionine metabolism is essential for reactive oxygen species (ROS) tolerance and virulence in many phytopathogenic fungi. However, the underlying regulatory mechanism of METR involved in this process is still unclear. In the present study, we generated AaMetB, AaMetC and AaMetX deletion mutants and compared these mutants with AaMetR disrupted mutants. Interestingly, we found that AaMetB, AaMetC and AaMetX are required for vegetative growth, conidiation, and pathogenicity in Alternaria alternata, but not for ROS tolerance and cysteine metabolism. Furthermore, we found that METR is involved in the biosynthesis of cysteine, which is an essential substrate for the biosynthesis of methionine and glutathione. This study emphasizes the critical roles of MetR, MetB, MetC, MetX in the regulation of cysteine and methionine metabolism, as well as the cross-link with glutathione-mediated ROS tolerance in phytopathogenic fungi, which provides a foundation for future investigations.
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Igbalajobi O, Gao J, Fischer R. The HOG Pathway Plays Different Roles in Conidia and Hyphae During Virulence of Alternaria alternata. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2020; 33:1405-1410. [PMID: 33104446 DOI: 10.1094/mpmi-06-20-0165-r] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The black mold Alternaria alternata causes dramatic losses in agriculture due to postharvest colonization and mycotoxin formation and is a weak pathogen on living plants. Fungal signaling processes are crucial for successful colonization of a host plant. Because the mitogen-activated protein kinase HogA is important for the expression of stress-associated genes, we tested a ∆hogA-deletion strain for pathogenicity. When conidia were used as inoculum, the ∆hogA-deletion strain was largely impaired in colonizing tomato and apple. In comparison, hyphae as inoculum colonized the fruit very well. Hence, HogA appears to be important only in the initial stages of plant colonization. A similar difference between conidial inoculum and hyphal inoculum was observed on artificial medium in the presence of different stress agents. Whereas wild-type conidia adapted well to different stresses, the ∆hogA-deletion strain failed to grow under the same conditions. With hyphae as inoculum, the wild type and the ∆hogA-deletion strain grew in a very similar way. At the molecular level, we observed upregulation of several catalase (catA, -B, and -D) and superoxide dismutase (sodA, -B, and -E) genes in germlings but not in hyphae after exposure to 4 mM hydrogen peroxide. The upregulation required the high osmolarity glycerol (HOG) pathway. In contrast, in mycelia, catD, sodA, sodB, and sodE were upregulated upon stress in the absence of HogA. Several other stress-related genes behaved in a similar way.
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Affiliation(s)
- Olumuyiwa Igbalajobi
- Karlsruhe Institute of Technology (KIT)-South Campus, Institute of Applied Biosciences, Department of Microbiology, Fritz-Haber-Weg 4,D-76131 Karlsruhe, Germany
| | - Jia Gao
- Karlsruhe Institute of Technology (KIT)-South Campus, Institute of Applied Biosciences, Department of Microbiology, Fritz-Haber-Weg 4,D-76131 Karlsruhe, Germany
| | - Reinhard Fischer
- Karlsruhe Institute of Technology (KIT)-South Campus, Institute of Applied Biosciences, Department of Microbiology, Fritz-Haber-Weg 4,D-76131 Karlsruhe, Germany
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Differential responses of genes and enzymes associated with ROS protective responses in the sugarcane smut fungus. Fungal Biol 2020; 124:1039-1051. [PMID: 33213784 DOI: 10.1016/j.funbio.2020.09.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 09/09/2020] [Accepted: 09/23/2020] [Indexed: 12/29/2022]
Abstract
The fungal pathogen Sporisorium scitamineum causes sugarcane smut disease. We have previously shown that resistant sugarcane plants induce ROS, coinciding with a delay in fungal colonization. Here, we investigated whether the fungus modifies the enzymatic antioxidant system in vitro and when colonizing sugarcane tissues in response to ROS. In vitro, the exposure to ROS did not affect cell integrity, and a combination of superoxide dismutases (SOD) and catalases (CAT) were active. In vitro, the fungus did not alter the expression of the transcriptional regulator Yap1 and the effector Pep1. The fungus activated distinct enzymes when colonizing plant tissues. Instead of CAT, S. scitamineum induced glutathione peroxidase (Gpx) expression only when colonizing smut-resistant plants. Yap1 had an earlier expression in both smut-susceptible and -resistant plants, with no apparent correlation with the expression of antioxidant genes sod, cat, gpx, or external redox imbalance. The expression of the effector pep1 was induced only in smut-resistant plants, potentially in response to ROS. These results collectively suggest that S. scitamineum copes with oxidative stress by inducing different mechanisms depending on the conditions (in vitro/in planta) and intensity of ROS. Moreover, the effector Pep1 is responsive to the stress imposed only by the sugarcane resistant genotype.
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Wu PC, Chen CW, Choo CYL, Chen YK, Yago JI, Chung KR. Proper Functions of Peroxisomes Are Vital for Pathogenesis of Citrus Brown Spot Disease Caused by Alternaria alternata. J Fungi (Basel) 2020; 6:jof6040248. [PMID: 33114679 PMCID: PMC7712655 DOI: 10.3390/jof6040248] [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: 09/17/2020] [Revised: 10/14/2020] [Accepted: 10/24/2020] [Indexed: 11/27/2022] Open
Abstract
In addition to the production of a host-selective toxin, the tangerine pathotype of Alternaria alternata must conquer toxic reactive oxygen species (ROS) in order to colonize host plants. The roles of a peroxin 6-coding gene (pex6) implicated in protein import into peroxisomes was functionally characterized to gain a better understanding of molecular mechanisms in ROS resistance and fungal pathogenicity. The peroxisome is a vital organelle involved in metabolisms of fatty acids and hydrogen peroxide in eukaryotes. Targeted deletion of pex6 had no impacts on the biogenesis of peroxisomes and cellular resistance to ROS. The pex6 deficient mutant (Δpex6) reduced toxin production by 40% compared to wild type and barely induce necrotic lesions on citrus leaves. Co-inoculation of purified toxin with Δpex6 conidia on citrus leaves, however, failed to fully restore lesion formation, indicating that toxin only partially contributed to the loss of Δpex6 pathogenicity. Δpex6 conidia germinated poorly and formed fewer appressorium-like structures (nonmelanized enlargement of hyphal tips) than wild type. Δpex6 hyphae grew slowly and failed to penetrate beyond the epidermal layers. Moreover, Δpex6 had thinner cell walls and lower viability. All of these defects resulting from deletion of pex6 could also account for the loss of Δpex6 pathogenicity. Overall, our results have demonstrated that proper peroxisome functions are of vital importance to pathogenesis of the tangerine pathotype of A. alternata.
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Affiliation(s)
- Pei-Ching Wu
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung Hsing University, Taichung 40227, Taiwan; (C.-W.C.); (C.Y.L.C.); (Y.-K.C.)
- Correspondence: (P.-C.W.); (K.-R.C.); Tel.: +886-4-22840780 (ext. 316) (P.-C.W.); +886-4-22840780 (ext. 301) (K.-R.C.)
| | - Chia-Wen Chen
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung Hsing University, Taichung 40227, Taiwan; (C.-W.C.); (C.Y.L.C.); (Y.-K.C.)
| | - Celine Yen Ling Choo
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung Hsing University, Taichung 40227, Taiwan; (C.-W.C.); (C.Y.L.C.); (Y.-K.C.)
| | - Yu-Kun Chen
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung Hsing University, Taichung 40227, Taiwan; (C.-W.C.); (C.Y.L.C.); (Y.-K.C.)
| | - Jonar I. Yago
- Plant Science Department, College of Agriculture, Nueva Vizcaya State University, Bayombong, Nueva Vizcaya 3700, Philippines;
| | - Kuang-Ren Chung
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung Hsing University, Taichung 40227, Taiwan; (C.-W.C.); (C.Y.L.C.); (Y.-K.C.)
- Correspondence: (P.-C.W.); (K.-R.C.); Tel.: +886-4-22840780 (ext. 316) (P.-C.W.); +886-4-22840780 (ext. 301) (K.-R.C.)
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Fu H, Chung K, Gai Y, Mao L, Li H. The basal transcription factor II H subunit Tfb5 is required for stress response and pathogenicity in the tangerine pathotype of Alternaria alternata. MOLECULAR PLANT PATHOLOGY 2020; 21:1337-1352. [PMID: 32776683 PMCID: PMC7488464 DOI: 10.1111/mpp.12982] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 06/25/2020] [Accepted: 07/20/2020] [Indexed: 05/16/2023]
Abstract
The basal transcription factor II H (TFIIH) is a multicomponent complex. In the present study, we characterized a TFIIH subunit Tfb5 by analysing loss- and gain-of-function mutants to gain a better understanding of the molecular mechanisms underlying stress resistance and pathogenicity in the citrus fungal pathogen Alternaria alternata. Tfb5 deficiency mutants (ΔAatfb5) decreased sporulation and pigmentation, and were impaired in the maintenance of colony surface hydrophobicity and cell wall integrity. ΔAatfb5 increased sensitivity to ultraviolet light, DNA-damaging agents, and oxidants. The expression of Aatfb5 was up-regulated in the wild type upon infection in citrus leaves, implicating the requirement of Aatfb5 in fungal pathogenesis. Biochemical and virulence assays revealed that ΔAatfb5 was defective in toxin production and cellwall-degrading enzymes, and failed to induce necrotic lesions on detached citrus leaves. Aatfb5 fused with green fluorescent protein (GFP) was localized in the cytoplasm and nucleus and physically interacted with another subunit, Tfb2, based on yeast two-hybrid and co-immunoprecipitation analyses. Transcriptome and Antibiotics & Secondary Metabolite Analysis Shell (antiSMASH) analyses revealed the positive and negative roles of Aatfb5 in the production of various secondary metabolites and in the regulation of many metabolic and biosynthetic processes in A. alternata. Aatfb5 may play a negative role in oxidative phosphorylation and a positive role in peroxisome biosynthesis. Two cutinase-coding genes (AaCut2 and AaCut15) required for full virulence were down-regulated in ΔAatfb5. Overall, this study expands our understanding of how A. alternata uses the basal transcription factor to deal with stress and achieve successful infection in the plant host.
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Affiliation(s)
- Huilan Fu
- Key Laboratory of Molecular Biology of Crop Pathogens and InsectsInstitute of BiotechnologyZhejiang UniversityHangzhouChina
| | - Kuang‐Ren Chung
- Department of Plant PathologyCollege of Agriculture and Natural ResourcesNational Chung‐Hsing UniversityTaichungTaiwan
| | - Yunpeng Gai
- Key Laboratory of Molecular Biology of Crop Pathogens and InsectsInstitute of BiotechnologyZhejiang UniversityHangzhouChina
| | - Lijuan Mao
- Analysis Center of Agrobiology and Environmental SciencesFaculty of Agriculture, Life and Environment SciencesZhejiang UniversityHangzhouChina
| | - Hongye Li
- Key Laboratory of Molecular Biology of Crop Pathogens and InsectsInstitute of BiotechnologyZhejiang UniversityHangzhouChina
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Wu PC, Chen CW, Choo CYL, Chen YK, Yago JI, Chung KR. Biotin biosynthesis affected by the NADPH oxidase and lipid metabolism is required for growth, sporulation and infectivity in the citrus fungal pathogen Alternaria alternata. Microbiol Res 2020; 241:126566. [PMID: 33032167 DOI: 10.1016/j.micres.2020.126566] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 06/30/2020] [Accepted: 07/23/2020] [Indexed: 02/06/2023]
Abstract
The tangerine pathotype of Alternaria alternata affects many citrus cultivars, resulting in yield losses. The capability to produce the host-selective toxin and cell-wall-degrading enzymes and to mitigate toxic reactive oxygen species is crucial for A. alternata pathogenesis to citrus. Little is known about nutrient availability within citrus tissues to the fungal pathogen. In the present study, we assess the infectivity of a biotin deficiency mutant (ΔbioB) and a complementation strain (CP36) on citrus leaves to determine how biotin impacts A. alternata pathogenesis. Growth and sporulation of ΔbioB are highly dependent on biotin. ΔbioB retains its ability to acquire and transport biotin from the surrounding environment. Growth deficiency of ΔbioB can also be partially restored by the presence of oleic acid or Tween 20, suggesting the requirement of biotin in lipid metabolism. Experimental evidence indicates that de novo biotin biosynthesis is regulated by the NADPH oxidase, implicating in the production of H2O2, and is affected by the function of peroxisomes. Three genes involved in the biosynthesis of biotin are clustered and co-regulated by biotin indicating a transcriptional feedback loop activation. Infectivity assays using fungal mycelium reveal that ΔbioB cultured on medium without biotin fails to infect citrus leaves; co-inoculation with biotin fully restores infectivity. The CP36 strain re-expressing a functional copy of bioB displays wild-type growth, sporulation and virulence. Taken together, we conclude that the attainability or accessibility of biotin is extremely restricted in citrus cells. A. alternata must be able to synthesize biotin in order to utilize nutrients for growth, colonization and development within the host.
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Affiliation(s)
- Pei-Ching Wu
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Chia-Wen Chen
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Celine Yen Ling Choo
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Yu-Kun Chen
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Jonar I Yago
- Plant Science Department, College of Agriculture, Nueva Vizcaya State University, Bayombong, Nueva Vizcaya, 3700, Philippines
| | - Kuang-Ren Chung
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung Hsing University, Taichung, 40227, Taiwan.
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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: 9] [Impact Index Per Article: 2.3] [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 Basic Leucine Zipper Transcription Factor PlBZP32 Associated with the Oxidative Stress Response Is Critical for Pathogenicity of the Lychee Downy Blight Oomycete Peronophythora litchii. mSphere 2020; 5:5/3/e00261-20. [PMID: 32493721 PMCID: PMC7273347 DOI: 10.1128/msphere.00261-20] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
In this study, we utilized the RNAi technique to investigate the functions of PlBZP32, which possesses a basic leucine zipper (bZIP)-PAS structure, and provided insights into the contributions of bZIP transcription factors to oxidative stress, the production of sporangia, the germination of cysts, and the pathogenicity of Peronophythora litchii. This study also revealed the role of PlBZP32 in regulating the enzymatic activities of extracellular peroxidases and laccases in the plant-pathogenic oomycete. Basic leucine zipper (bZIP) transcription factors are widespread in eukaryotes, including plants, animals, fungi, and oomycetes. However, the functions of bZIPs in oomycetes are rarely known. In this study, we identified a bZIP protein possessing a special bZIP-PAS structure in Peronophythora litchii, named PlBZP32. We found that PlBZP32 is upregulated in zoospores, in cysts, and during invasive hyphal growth. We studied the functions of PlBZP32 using the RNAi technique to suppress the expression of this gene. PlBZP32-silenced mutants were more sensitive to oxidative stress, showed a lower cyst germination rate, and produced more sporangia than the wild-type strain SHS3. The PlBZP32-silenced mutants were also less invasive on the host plant. Furthermore, we analyzed the activities of extracellular peroxidases and laccases and found that silencing PlBZP32 decreased the activities of P. litchii peroxidase and laccase. To our knowledge, this is the first report that the functions of a bZIP-PAS protein are associated with oxidative stress, asexual development, and pathogenicity in oomycetes. IMPORTANCE In this study, we utilized the RNAi technique to investigate the functions of PlBZP32, which possesses a basic leucine zipper (bZIP)-PAS structure, and provided insights into the contributions of bZIP transcription factors to oxidative stress, the production of sporangia, the germination of cysts, and the pathogenicity of Peronophythora litchii. This study also revealed the role of PlBZP32 in regulating the enzymatic activities of extracellular peroxidases and laccases in the plant-pathogenic oomycete.
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Zhang MM, Wang ZQ, Xu X, Huang S, Yin WX, Luo C. MfOfd1 is crucial for stress responses and virulence in the peach brown rot fungus Monilinia fructicola. MOLECULAR PLANT PATHOLOGY 2020; 21:820-833. [PMID: 32319202 PMCID: PMC7214477 DOI: 10.1111/mpp.12933] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Revised: 02/23/2020] [Accepted: 02/24/2020] [Indexed: 06/01/2023]
Abstract
Monilinia fructicola is the most widely distributed species among the Monilinia genus in the world, and causes blossom blight, twig canker, and fruit rot on Rosaceae fruits. To date, studies on genomics and pathogenicity are limited in M. fructicola. In this study, we identified a redox-related gene, MfOfd1, which was significantly up-regulated at 1 hr after inoculation of M. fructicola on peach fruits. We used the clustered regulatory inter-spaced short palindromic repeats (CRISPR)/Cas9 system combined with homologous recombination to determine the function of the MfOfd1 gene. The results showed that the sporulation of knockdown transformants was reduced by 53% to 83%. The knockdown transformants showed increased sensitivity to H2 O2 and decreased virulence on peach fruits compared to the wild-type isolate Bmpc7. It was found that H2 O2 could stimulate the expression of MfOfd1 in the wild-type isolate. The transformants were also more sensitive to exogenous osmotic stress, such as glycerol, d-sorbitol, and NaCl, and to dicarboximide fungicides (iprodione and dimethachlon). These results indicate that the MfOfd1 gene plays an important role in M. fructicola in sporulation, oxidative response, osmotic stress tolerance, and virulence.
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Affiliation(s)
- Ming-Ming Zhang
- The Key Lab of Horticultural Plant BiologyMinistry of EducationHuazhong Agricultural UniversityWuhanChina
| | - Zuo-Qian Wang
- Institute of Plant Protection and Soil FertilizerHubei Academy of Agricultural ScienceWuhanChina
| | - Xiao Xu
- The Key Lab of Horticultural Plant BiologyMinistry of EducationHuazhong Agricultural UniversityWuhanChina
| | - Song Huang
- The Key Lab of Horticultural Plant BiologyMinistry of EducationHuazhong Agricultural UniversityWuhanChina
| | - Wei-Xiao Yin
- Key Lab of Crop Disease Monitoring and Safety Control in Hubei Province and College of Plant Science and TechnologyHuazhong Agricultural UniversityWuhanChina
| | - Chao‐Xi Luo
- The Key Lab of Horticultural Plant BiologyMinistry of EducationHuazhong Agricultural UniversityWuhanChina
- Key Lab of Crop Disease Monitoring and Safety Control in Hubei Province and College of Plant Science and TechnologyHuazhong Agricultural UniversityWuhanChina
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The siderophore repressor SreA maintains growth, hydrogen peroxide resistance, and cell wall integrity in the phytopathogenic fungus Alternaria alternata. Fungal Genet Biol 2020; 139:103384. [PMID: 32278718 DOI: 10.1016/j.fgb.2020.103384] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 03/25/2020] [Accepted: 03/31/2020] [Indexed: 01/18/2023]
Abstract
The siderophore-mediated iron uptake machinery is required by the tangerine pathotype of Alternaria alternata to colonize host plants. The present study reports the functions of the GATA-type transcription regulator SreA by analyzing loss- and gain-of-function mutants. The expression of sreA is transiently upregulated by excess iron. The sreA deficiency mutant (ΔsreA) shows severe growth defect but produces ACT toxin and incites necrotic lesions on citrus leaves as efficiently as wild type. SreA suppresses the expression of genes encoding polypeptides required for siderophore biosynthesis and transport under iron-replete conditions. Under iron-replete conditions, SreA impacts the expression of the genes encoding the NADPH oxidase complex involved in H2O2 production. SreA negatively impacts H2O2 resistance as ΔsreA increases resistance to H2O2. However, sreA deficiency has no effects on the expression of genes encoding several key factors (Yap1, Hog1, and Skn7) involved in oxidative stress resistance. ΔsreA increases resistance to calcofluor white and Congo red, which may suggest a role of SreA in the maintenance of cell wall integrity. Those are novel phenotypes associated with fungal sreA. Overall, our results indicate that SreA is required to protect fungal cells from cytotoxicity caused by excess iron. The results also highlight the regulatory functions of SreA and provide insights into the critical role of siderophore-mediated iron homeostasis in resistance to oxidative stress in A. alternata.
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Wang PH, Wu PC, Huang R, Chung KR. The Role of a Nascent Polypeptide-Associated Complex Subunit Alpha in Siderophore Biosynthesis, Oxidative Stress Response, and Virulence in Alternaria alternata. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2020; 33:668-679. [PMID: 31928525 DOI: 10.1094/mpmi-11-19-0315-r] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The present study demonstrates that a nascent polypeptide-associated complex α subunit (Nac1) functions as a transcriptional regulator and plays both positive and negative roles in a vast array of functions in Alternaria alternata. Gain- and loss-of-function studies reveal that Nac1 is required for the formation and germination of conidia, likely via the regulation of Fus3 and Slt2 mitogen-activated protein kinase (MAPK)-coding genes, both implicated in conidiation. Nac1 negatively regulates hyphal branching and the production of cell wall-degrading enzymes. Importantly, Nac1 is required for the biosynthesis of siderophores, a novel phenotype that has not been reported to be associated with a Nac in fungi. The expression of Nac1 is positively regulated by iron, as well as by the Hog1 MAPK and the NADPH-dependent oxidase (Nox) complex. Nac1 confers cellular susceptibility to reactive oxygen species (ROS) likely via negatively regulating the expression of the genes encoding Yap1, Skn7, Hog1, and Nox, all involved in ROS resistance. The involvement of Nac1 in sensitivity to glucose-, mannitol-, or sorbitol-induced osmotic stress could be due to its ability to suppress the expression of Skn7. The requirement of Nac1 in resistance to salts is unlikely mediated through the transcriptional activation of Hog1. Although Nac1 plays no role in toxin production, Nac1 is required for fungal full virulence. All observed deficiencies can be restored by re-expressing a functional copy of Nac1, confirming that Nac1 contributes to the phenotypes. Thus, a dynamic regulation of gene expression via Nac1 is critical for developmental, physiological, and pathological processes of A. alternata.
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Affiliation(s)
- Pin-Hua Wang
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Pei-Ching Wu
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Richie Huang
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Kuang-Ren Chung
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung Hsing University, Taichung, 40227, Taiwan
- Ph.D. Program in Microbial Genomics, National Chung Hsing University and Academia Sinica, Taichung 40227, Taiwan
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Mendoza-Martínez AE, Cano-Domínguez N, Aguirre J. Yap1 homologs mediate more than the redox regulation of the antioxidant response in filamentous fungi. Fungal Biol 2019; 124:253-262. [PMID: 32389287 DOI: 10.1016/j.funbio.2019.04.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 04/02/2019] [Accepted: 04/03/2019] [Indexed: 10/27/2022]
Abstract
The regulation of gene expression in response to increased levels of reactive oxygen species (ROS) is a ubiquitous response in aerobic organisms. However, different organisms use different strategies to perceive and respond to high ROS levels. Yeast Yap1 is a paradigmatic example of a specific mechanism used by eukaryotic cells to link ROS sensing and gene regulation. The activation of this transcription factor by H2O2 is mediated by peroxiredoxins, which are widespread enzymes that use cysteine thiols to sense ROS, as well as to catalyze the reduction of peroxides to water. In filamentous fungi, Yap1 homologs and peroxiredoxins also are major regulators of the antioxidant response. However, Yap1 homologs are involved in a wider array of processes by regulating genes involved in nutrient assimilation, secondary metabolism, virulence and development. Such novel functions illustrate the divergent roles of ROS and other oxidizing compounds as important regulatory signaling molecules.
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Affiliation(s)
- Ariann E Mendoza-Martínez
- Departamento de Biología Celular y del Desarrollo, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-242, 04510 Ciudad de México, Mexico
| | - Nallely Cano-Domínguez
- Departamento de Biología Celular y del Desarrollo, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-242, 04510 Ciudad de México, Mexico
| | - Jesús Aguirre
- Departamento de Biología Celular y del Desarrollo, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-242, 04510 Ciudad de México, Mexico.
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Lu K, Zhang M, Yang R, Zhang M, Guo Q, Baek KH, Xu H. The MAP Kinase Kinase Gene AbSte7 Regulates Multiple Aspects of Alternaria brassicicola Pathogenesis. THE PLANT PATHOLOGY JOURNAL 2019; 35:91-99. [PMID: 31007639 PMCID: PMC6464198 DOI: 10.5423/ppj.oa.07.2018.0125] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 11/15/2018] [Accepted: 12/06/2018] [Indexed: 05/13/2023]
Abstract
Mitogen-activated protein kinase (MAPK) cascades in fungi are ubiquitously conserved signaling pathways that regulate stress responses, vegetative growth, pathogenicity, and many other developmental processes. Previously, we reported that the AbSte7 gene, which encodes a mitogen-activated protein kinase kinase (MAPKK) in Alternaria brassicicola, plays a central role in pathogenicity against host cabbage plants. In this research, we further characterized the role of AbSte7 in the pathogenicity of this fungus using ΔAbSte7 mutants. Disruption of the AbSte7 gene of A. brassicicola reduced accumulation of metabolites toxic to the host plant in liquid culture media. The ΔAbSte7 mutants could not efficiently detoxify cruciferous phytoalexin brassinin, possibly due to reduced expression of the brassinin hydrolase gene involved in detoxifying brassinin. Disruption of the AbSte7 gene also severely impaired fungal detoxification of reactive oxygen species. AbSte7 gene disruption reduced the enzymatic activity of cell wall-degrading enzymes, including cellulase, β-glucosidase, pectin methylesterase, polymethyl-galacturonase, and polygalacturonic acid transeliminase, during host plant infection. Altogether, the data strongly suggest the MAPKK gene AbSte7 plays a pivotal role in A. brassicicola during host infection by regulating multiple steps, and thus increasing pathogenicity and inhibiting host defenses.
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Affiliation(s)
- Kai Lu
- Department of Plant Protection, Shandong Agricultural University, Tai’an 271018,
China
| | - Min Zhang
- Department of Plant Protection, Shandong Agricultural University, Tai’an 271018,
China
| | - Ran Yang
- Department of Plant Protection, Shandong Agricultural University, Tai’an 271018,
China
| | - Min Zhang
- Department of Plant Protection, Shandong Agricultural University, Tai’an 271018,
China
| | - Qinjun Guo
- Department of Plant Protection, Shandong Agricultural University, Tai’an 271018,
China
| | - Kwang-Hyun Baek
- Department of Biotechnology, Yeungnam University, Gyeongsan, Gyeongbuk 38541,
Korea
- Co-corresponding authors: H. Xu, Phone) +86-538-824-1575, FAX) +86-538-824-1324, E-mail) . K.-H. Baek, Phone) +82-53-810-3029, FAX) +82-53-810-4769, E-mail)
| | - Houjuan Xu
- Department of Plant Protection, Shandong Agricultural University, Tai’an 271018,
China
- Co-corresponding authors: H. Xu, Phone) +86-538-824-1575, FAX) +86-538-824-1324, E-mail) . K.-H. Baek, Phone) +82-53-810-3029, FAX) +82-53-810-4769, E-mail)
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Simaan H, Lev S, Horwitz BA. Oxidant-Sensing Pathways in the Responses of Fungal Pathogens to Chemical Stress Signals. Front Microbiol 2019; 10:567. [PMID: 30941117 PMCID: PMC6433817 DOI: 10.3389/fmicb.2019.00567] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 03/05/2019] [Indexed: 12/04/2022] Open
Abstract
Host defenses expose fungal pathogens to oxidants and antimicrobial chemicals. The fungal cell employs conserved eukaryotic signaling pathways and dedicated transcription factors to program its response to these stresses. The oxidant-sensitive transcription factor of yeast, YAP1, and its orthologs in filamentous fungi, are central to tolerance to oxidative stress. The C-terminal domain of YAP1 contains cysteine residues that, under oxidizing conditions, form an intramolecular disulfide bridge locking the molecule in a conformation where the nuclear export sequence is masked. YAP1 accumulates in the nucleus, promoting transcription of genes that provide the cell with the ability to counteract oxidative stress. Chemicals including xenobiotics and plant signals can also promote YAP1 nuclearization in yeast and filamentous fungi. This could happen via direct or indirect oxidative stress, or by a different biochemical pathway. Plant phenolics are known antioxidants, yet they have been shown to elicit cellular responses that would usually be triggered to counter oxidant stress. Here we will discuss the evidence that YAP1 and MAPK pathways respond to phenolic compounds. Following this and other examples, we explore here how oxidative-stress sensing networks of fungi might have evolved to detect chemical stressors. Furthermore, we draw functional parallels between fungal YAP1 and mammalian Keap1-Nrf2 signaling systems.
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Affiliation(s)
- Hiba Simaan
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel
| | - Sophie Lev
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, Westmead, NSW, Australia
| | - Benjamin A Horwitz
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel
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Jain M, Munoz-Bodnar A, Zhang S, Gabriel DW. A Secreted 'Candidatus Liberibacter asiaticus' Peroxiredoxin Simultaneously Suppresses Both Localized and Systemic Innate Immune Responses In Planta. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2018; 31:1312-1322. [PMID: 29953333 DOI: 10.1094/mpmi-03-18-0068-r] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The oxidative (H2O2) burst is a seminal feature of the basal plant defense response to attempted pathogen invasions. In 'Candidatus Liberibacter asiaticus' UF506, expression of the SC2 prophage-encoded secreted peroxidase (F489_gp15) increases bacterial fitness and delays symptom progression in citrus. Two chromosomal 1-Cys peroxiredoxin genes, CLIBASIA_RS00940 (Lasprx5) and CLIBASIA_RS00445 (Lasbcp), are conserved among all sequenced 'Ca. L. asiaticus' strains, including those lacking prophages. Both LasBCP and LasdPrx5 have only a single conserved peroxidatic Cys (CP/SH) and lack the resolving Cys (CR/SH). Lasprx5 appeared to be a housekeeping gene with similar moderate transcript abundance in both 'Ca. L. asiaticus'-infected psyllids and citrus. By contrast, Lasbcp was expressed only in planta, similar to the expression of the SC2 peroxidase. Since 'Ca. L. asiaticus' is uncultured, Lasbcp and Lasprx5 were functionally validated in a cultured surrogate species, Liberibacter crescens, and both genes significantly increased oxidative stress tolerance and cell viability in culture. LasBCP was nonclassically secreted and, in L. crescens, conferred 214-fold more resistance to tert-butyl hydroperoxide (tBOOH) than wild type. Transient overexpression of Lasbcp in tobacco suppressed H2O2-mediated transcriptional activation of RbohB, the key gatekeeper of the systemic plant defense signaling cascade. Lasbcp expression did not interfere with the perception of 'Ca. L. asiaticus' flagellin (flg22Las) but interrupted the downstream activation of RbohB and stereotypical deposition of callose in tobacco. Critically, LasBCP also protected against tBOOH-induced peroxidative degradation of lipid membranes in planta, preventing subsequent accumulation of antimicrobial oxylipins that can also trigger the localized hypersensitive cell death response.
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Affiliation(s)
- Mukesh Jain
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611, U.S.A
| | | | - Shujian Zhang
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611, U.S.A
| | - Dean W Gabriel
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611, U.S.A
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The methionine biosynthesis regulator AaMetR contributes to oxidative stress tolerance and virulence in Alternaria alternata. Microbiol Res 2018; 219:94-109. [PMID: 30642471 DOI: 10.1016/j.micres.2018.11.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 11/12/2018] [Accepted: 11/23/2018] [Indexed: 12/29/2022]
Abstract
The tangerine pathotype of A. alternata, which produces a unique host-selective ACT toxin causes brown spots on citrus leaves and fruits. In this study, we report a methionine biosynthesis regulator (MetR), which belong to bZIP transcription factor, is required for methionine metabolism, oxidative stress tolerance and pathogenicity. We generated two ΔAaMetR mutants in the tangerine pathotype of Alternaria alternata and investigated the resulting mutant phenotypes. The ΔAaMetR disruption mutant grew poorly in the absence of methionine and unable to produce conidia. Furthermore, pathogenicity tests have shown that ΔAaMetR mutant on their tangerine host can neither penetrate nor cause disease. These ΔAaMetR mutants exhibit an increased sensitivity to exogenous H2O2 and many ROS generating oxidants. To elucidate the transcription network of AaMetR, we performed RNA-Seq experiments on wild-type and ΔAaMetR mutant and identified genes that were differentially expressed between the two genotypes. Transcriptome data demonstrated that AaMetR contributes in many other biological processes including ROS detoxification, sulfur transfer, and amino acid metabolism. Comparative transcriptome analysis indicated that the ΔAaMetR mutant up-regulated several genes involved in cysteine and methionine metabolism. In conclusion, our results highlight the global regulatory role of AaMetR in cysteine and methionine metabolism and provide new insights into the crucial role of ROS detoxification, sporulation and pathogenicity in the tangerine pathotype of A. alternata.
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Lin HC, Yu PL, Chen LH, Tsai HC, Chung KR. A Major Facilitator Superfamily Transporter Regulated by the Stress-Responsive Transcription Factor Yap1 Is Required for Resistance to Fungicides, Xenobiotics, and Oxidants and Full Virulence in Alternaria alternata. Front Microbiol 2018; 9:2229. [PMID: 30279684 PMCID: PMC6153361 DOI: 10.3389/fmicb.2018.02229] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2018] [Accepted: 08/31/2018] [Indexed: 11/29/2022] Open
Abstract
Alternaria alternata relies on the ability to produce a host-selective toxin and to detoxify reactive oxygen species to successfully colonize the host. An A. alternata major facilitator superfamily transporter designated AaMFS54 was functionally characterized by analysis of loss- and gain-of-function mutations to better understand the factors required for fungal pathogenesis. AaMFS54 was originally identified from a wild-type expression library after being subtracted with that of a mutant impaired for the oxidative stress-responsive transcription regulator Yap1. AaMFS54 contains 14 transmembrane helixes. Fungal mutant lacking AaMFS54 produced fewer conidia and increased sensitivity to many potent oxidants (potassium superoxide and singlet-oxygen generating compounds), xenobiotics (2,3,5-triiodobenzoic acid and 2-chloro-5-hydroxypyridine), and fungicides (clotrimazole, fludioxonil, vinclozolin, and iprodione). AaMFS54 mutant induced necrotic lesion sizes similar to those induced by wild-type on leaves of susceptible citrus cultivars after point inoculation with spore suspensions. However, the mutant produced smaller colonies and less fluffy hyphae on the affected leaves. Virulence assays on citrus leaves inoculated by spraying with spores revealed that AaMFS54 mutant induced less severe lesions than wild-type, indicating the requirement of AaMFS54 in pathogenesis. All defective phenotypes were restored in a strain re-acquiring a functional copy of AaMFS54. Northern blotting analysis revealed that the expression of AaMFS54 was suppressed by xenobiotics. The current studies indicate that the Yap1-mediated transporter plays a role in resistance to toxic oxidants and fungicides in A. alternata. The relationships of MFS transporters with other regulatory components conferring stress resistance and A. alternata pathogenesis are also discussed.
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Affiliation(s)
- Hsien-Che Lin
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung-Hsing University, Taichung, Taiwan
| | - Pei-Ling Yu
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung-Hsing University, Taichung, Taiwan
| | - Li-Hung Chen
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung-Hsing University, Taichung, Taiwan
| | - Hsieh-Chin Tsai
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung-Hsing University, Taichung, Taiwan
| | - Kuang-Ren Chung
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung-Hsing University, Taichung, Taiwan
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Feng H, Zhang M, Zhao Y, Li C, Song L, Huang L. Secreted peroxidases VmPODs play critical roles in the conidiation, H 2O 2 sensitivity and pathogenicity of Valsa mali. Fungal Genet Biol 2018; 119:20-28. [PMID: 30125671 DOI: 10.1016/j.fgb.2018.08.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 07/02/2018] [Accepted: 08/15/2018] [Indexed: 01/22/2023]
Abstract
Apple Valsa canker, caused by the necrotrophic pathogen Valsa mali, is a devastating disease of apples and causes great financial loss in East Asia. Improving the understanding of apple - V. mali interactions will contribute to disease management. In this study, three predicted secreted peroxidases (VmPOD1, VmPOD2 and VmPOD3) were uncovered based on the secretome and genome information of V. mali. Phylogenetic analysis showed that VmPOD1 is a catalase peroxidase, VmPOD2 is a chloroperoxidase, and VmPOD3 is a plant peroxidase-like peroxidase. The secretion function of the corresponding genes was confirmed using the yeast invertase secretion system. The deletion of VmPODs did not affect the vegetative growth when the mutants (ΔVmPOD1, ΔVmPOD2 and ΔVmPOD3) and the wild-type strain 03-8 were grown on PDA medium at 25 °C in the dark. However, the respective mutants showed impaired conidiation ability with fewer pycnidia, and all gene deletion mutants grew more slowly than 03-8 on PDA supplemented with H2O2 (Final concentration: 0.06 mol/L H2O2). In addition, VmPOD1 and VmPOD2 were found to be significantly up-regulated at an early infection stage, and VmPOD3 showed sustained high expression during the whole infection progress of V. mali. In addition, the virulence of ΔVmPOD3 was significantly reduced, implying that VmPOD3 plays a critical role during the interaction between V. mali and apple. All of the defective phenotypes could be nearly restored by re-introducing the wild-type VmPOD1, VmPOD2 or VmPOD3 allele. The results enhanced our understanding of the secreted peroxidase, which could also act as a type of virulence factor from the necrotrophic pathogen V. mali and provided new insight into the role of the pathogen-secreted peroxidase.
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Affiliation(s)
- Hao Feng
- College of Plant Protection and State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Mian Zhang
- College of Plant Protection and State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Yuhuan Zhao
- College of Plant Protection and State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Chen Li
- College of Plant Protection and State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Linlin Song
- College of Plant Protection and State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Lili Huang
- College of Plant Protection and State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling, Shaanxi 712100, China.
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Thioredoxin and Glutaredoxin Systems Required for Oxidative Stress Resistance, Fungicide Sensitivity, and Virulence of Alternaria alternata. Appl Environ Microbiol 2018; 84:AEM.00086-18. [PMID: 29752269 DOI: 10.1128/aem.00086-18] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 05/04/2018] [Indexed: 01/07/2023] Open
Abstract
This study determined the function of thioredoxin and glutaredoxin systems in the phytopathogenic fungus Alternaria alternata via analyzing mutants obtained from the targeted deletion of genes encoding thioredoxin peroxidase (Tsa1), thioredoxin reductase (Trr1), and glutathione reductase (Glr1). Trr1 and Glr1, but not Tsa1, are required for growth and conidiation. The reduced growth and conidiation seen in the Trr1 or Glr1 deletion mutant can be restored by glutathione. Deletion mutants showing growth inhibition by oxidants are defective for H2O2 detoxification and induce smaller lesions on citrus leaves. Trr1 and Glr1, but not Tsa1, also contribute to NaCl resistance. Glr1 is required for sorbitol resistance and is responsible for resistance to mancozeb and boscalid but not chlorothalonil fungicides, a novel phenotype that has not been reported in fungi. Trr1 is required for resistance to boscalid and chlorothalonil fungicides but confers susceptibility to mancozeb. The Tsa1 deletion mutant displays wild-type sensitivity to the tested fungicides. The expression of Tsa1 and Trr1 is regulated by the oxidative stress responsive regulators Yap1, Hog1, and Skn7. The expression of Tsa1, but not Trr1, is also regulated indirectly by the NADPH oxidase. The results indicate that the capability to resist oxidative stress is required for virulence of A. alternataIMPORTANCE The thioredoxin and glutaredoxin systems are important thiol antioxidant systems in cells, and knowledge of these two systems in the plant-pathogenic fungus A. alternata is useful for finding new strategies to reduce the virulence of this pathogen. In this study, we demonstrated that thiol antioxidant system-related genes (Tsa1, Trr1, and Glr1) are required for H2O2 detoxification and virulence in A. alternata Moreover, deletion of Trr1 results in hypersensitivity to the fungicides chlorothalonil and boscalid, and Glr1 deletion mutants are highly sensitive to mancozeb, which is the fungicide mostly used in citrus fields. Therefore, our findings demonstrate that the ability to detoxify reactive oxygen species (ROS) plays a critical role in pathogenesis on citrus and provide novel insights into the physiological functions of thiol-containing systems in fungicide sensitivity for A. alternata.
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Tan X, Sun J, Ning H, Qin Z, Miao Y, Sun T, Zhang X. De novo transcriptome sequencing and comprehensive analysis of the heat stress response genes in the basidiomycetes fungus Ganoderma lucidum. Gene 2018; 661:139-151. [PMID: 29605602 DOI: 10.1016/j.gene.2018.03.093] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 02/14/2018] [Accepted: 03/28/2018] [Indexed: 12/22/2022]
Abstract
Ganoderma lucidum is a valuable basidiomycete with numerous pharmacological compounds, which is widely consumed throughout China. We previously found that the polysaccharide content of Ganoderma lucidum fruiting bodies could be significantly improved by 45.63% with treatment of 42 °C heat stress (HS) for 2 h. To further investigate genes involved in HS response and explore the mechanisms of HS regulating the carbohydrate metabolism in Ganoderma lucidum, high-throughput RNA-Seq was conducted to analyse the difference between control and heat-treated mycelia at transcriptome level. We sequenced six cDNA libraries with three from control group (mycelia cultivated at 28 °C) and three from heat-treated group (mycelia subjected to 42 °C for 2 h). A total of 99,899 transcripts were generated using Trinity method and 59,136 unigenes were annotated by seven public databases. Among them, 2790 genes were identified to be differential expressed genes (DEGs) under HS condition, which included 1991 up-regulated and 799 down-regulated. 176 DEGs were then manually classified into five main responsive-related categories according to their putative functions and possible metabolic pathways. These groups include stress resistance-related factors; protein assembly, transportation and degradation; signal transduction; carbohydrate metabolism and energy provision-related process; other related functions, suggesting that a series of metabolic pathways in Ganoderma lucidum are activated by HS and the response mechanism involves a complex molecular network which needs further study. Remarkably, 48 DEGs were found to regulate carbohydrate metabolism, both in carbohydrate hydrolysis for energy provision and polysaccharide synthesis. In summary, this comprehensive transcriptome analysis will provide enlarged resource for further investigation into the molecular mechanisms of basidiomycete under HS condition.
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Affiliation(s)
- Xiaoyan Tan
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science & Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Junshe Sun
- Chinese Academy of Agricultural Engineering, Beijing 100125, China
| | - Huijuan Ning
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science & Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Zifang Qin
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science & Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Yuxin Miao
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science & Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Tian Sun
- Tianfangjian (China) Pharma Company Ltd, Guangzhou 510623, China.
| | - Xiuqing Zhang
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science & Nutritional Engineering, China Agricultural University, Beijing 100083, China.
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Wang M, Yang X, Ruan R, Fu H, Li H. Csn5 Is Required for the Conidiogenesis and Pathogenesis of the Alternaria alternata Tangerine Pathotype. Front Microbiol 2018; 9:508. [PMID: 29616013 PMCID: PMC5870056 DOI: 10.3389/fmicb.2018.00508] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 03/06/2018] [Indexed: 11/13/2022] Open
Abstract
The COP9 signalosome (CSN) is a highly conserved protein complex involved in the ubiquitin-proteasome system. Its metalloisopeptidase activity resides in subunit 5 (CSN5). Functions of csn5 in phytopathogenic fungi are poorly understood. Here, we knocked out the csn5 ortholog (Aacsn5) in the tangerine pathotype of Alternaria alternata. The ΔAacsn5 mutant showed a moderately reduced growth rate compared to the wildtype strain and was unable to produce conidia. The growth of ΔAacsn5 mutant was not affected in response to oxidative and osmotic stresses. Virulence assays revealed that ΔAacsn5 induced no or significantly reduced necrotic lesions on detached citrus leaves. The defects in hyphal growth, conidial sporulation, and pathogenicity of ΔAacsn5 were restored by genetic complementation of the mutant with wildtype Aacsn5. To explore the molecular mechanisms of conidiation and pathogenesis underlying Aacsn5 regulation, we systematically examined the transcriptomes of both ΔAacsn5 and the wildtype. Generally, 881 genes were overexpressed and 777 were underexpressed in the ΔAacsn5 mutant during conidiation while 694 overexpressed and 993 underexpressed during infection. During asexual development, genes related to the transport processes and nitrogen metabolism were significantly downregulated; the expression of csn1-4 and csn7 in ΔAacsn5 was significantly elevated; secondary metabolism gene clusters were broadly affected; especially, the transcript level of the whole of cluster 28 and 30 was strongly induced. During infection, the expression of the host-specific ACT toxin gene cluster which controls the biosynthesis of the citrus specific toxin was significantly repressed; many other SM clusters with unknown products were also regulated; 86 out of 373 carbohydrate-active enzymes responsible for breaking down the plant dead tissues showed uniquely decreased expression. Taken together, our results expand our understanding of the roles of csn5 on conidiation and pathogenicity in plant pathogenic fungi and provide a foundation for future investigations.
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Affiliation(s)
- Mingshuang Wang
- Key Lab of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Xiao Yang
- Key Lab of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Ruoxin Ruan
- Key Lab of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, China.,Hangzhou Academy of Agricultural Sciences, Hangzhou, China
| | - Huilan Fu
- Key Lab of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Hongye Li
- Key Lab of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, China
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Lee Y, Son H, Shin JY, Choi GJ, Lee Y. Genome-wide functional characterization of putative peroxidases in the head blight fungus Fusarium graminearum. MOLECULAR PLANT PATHOLOGY 2018; 19:715-730. [PMID: 28387997 PMCID: PMC6638050 DOI: 10.1111/mpp.12557] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 03/28/2017] [Accepted: 04/01/2017] [Indexed: 06/01/2023]
Abstract
Reactive oxygen species (ROS) are associated with various developmental processes and host-pathogen interactions in pathogenic fungi. Peroxidases are a group of ROS-detoxifying enzymes that are involved in the oxidative stress response and in a variety of physiological processes. In this study, we performed a genome-wide functional characterization of putative peroxidase genes in Fusarium graminearum, a head blight pathogen of cereal crops. We identified 31 putative peroxidase genes and generated deletion mutants for these genes. Twenty-six of the deletion mutants showed developmental phenotypes indistinguishable from that of the wild-type, and five deletion mutants exhibited phenotypic changes in at least one phenotypic category. Four deletion mutants, fca6, fca7, fpx1 and fpx15, showed increased sensitivity to extracellular H2 O2 . Deletion mutants of FCA7 also exhibited reduced virulence and increased trichothecene production compared with those of the wild-type strain, suggesting that Fca7 may play an important role in the host-pathogen interaction in F. graminearum. To identify the transcription factors (TFs) regulating FCA6, FCA7, FPX1 and FPX15 in response to oxidative stress, we screened an F. graminearum TF mutant library for growth in the presence of H2 O2 and found that multiple TFs co-regulated the expression of FCA7 under oxidative stress conditions. These results demonstrate that a complex network of transcriptional regulators of antioxidant genes is involved in oxidative stress responses in this fungus. Moreover, our study provides insights into the roles of peroxidases in developmental processes and host-pathogen interactions in plant-pathogenic fungi.
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Affiliation(s)
- Yoonji Lee
- Department of Agricultural BiotechnologySeoul National UniversitySeoul08826South Korea
| | - Hokyoung Son
- Center for Food and BioconvergenceSeoul National UniversitySeoul08826South Korea
| | - Ji Young Shin
- Department of Agricultural BiotechnologySeoul National UniversitySeoul08826South Korea
| | - Gyung Ja Choi
- Eco‐friendly New Materials Research Group, Research Center for Biobased Chemistry, Division of Convergence ChemistryKorea Research Institute of Chemical TechnologyDaejeon34114South Korea
| | - Yin‐Won Lee
- Department of Agricultural BiotechnologySeoul National UniversitySeoul08826South Korea
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Segal LM, Wilson RA. Reactive oxygen species metabolism and plant-fungal interactions. Fungal Genet Biol 2018; 110:1-9. [DOI: 10.1016/j.fgb.2017.12.003] [Citation(s) in RCA: 94] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 12/04/2017] [Accepted: 12/06/2017] [Indexed: 11/26/2022]
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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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