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Zhang R, Liu X, Xu J, Chen C, Tang Z, Wu C, Li X, Su L, Liu M, Yang L, Li G, Zhang H, Wang P, Zhang Z. MoRgs3 functions in intracellular reactive oxygen species perception-integrated cAMP signaling to promote appressorium formation in Magnaporthe oryzae. mBio 2024:e0099624. [PMID: 38980036 DOI: 10.1128/mbio.00996-24] [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: 04/02/2024] [Accepted: 06/12/2024] [Indexed: 07/10/2024] Open
Abstract
Regulator of G-protein signaling (RGS) proteins exhibit GTPase-accelerating protein activities to govern G-protein function. In the rice blast fungus Magnaporthe oryzae, there is a family of at least eight RGS and RGS-like proteins (MoRgs1 to MoRgs8), each exhibiting distinct or shared functions in the growth, appressorium formation, and pathogenicity. MoRgs3 recently emerged as one of the crucial regulators that senses intracellular oxidation during appressorium formation. To explore this unique regulatory mechanism of MoRgs3, we identified the nucleoside diphosphate kinase MoNdk1 that interacts with MoRgs3. MoNdk1 phosphorylates MoRgs3 under induced intracellular reactive oxygen species levels, and MoRgs3 phosphorylation is required for appressorium formation and pathogenicity. In addition, we showed that MoRgs3 phosphorylation determines its interaction with MoCrn1, a coronin-like actin-binding protein homolog, which regulates MoRgs3 internalization. Finally, we provided evidence demonstrating that MoRgs3 functions in MoMagA-mediated cAMP signaling to regulate normal appressorium induction. By revealing a novel signal perception mechanism, our studies highlighted the complexity of regulation during the appressorium function and pathogenicity of the blast fungus. IMPORTANCE We report that MoRgs3 becomes phosphorylated in an oxidative intracellular environment during the appressorium formation stage. We found that this phosphorylation is carried out by MoNdk1, a nucleoside diphosphate kinase. In addition, this phosphorylation leads to a higher binding affinity between MoRgs3 and MoCrn1, a coronin-like actin-binding protein that was implicated in the endocytic transport of several other RGS proteins of Magnaporthe oryzae. We further found that the internalization of MoRgs3 is indispensable for its GTPase-activating protein function toward the Gα subunit MoMagA. Importantly, we characterized how such cellular regulatory events coincide with cAMP signaling-regulated appressorium formation and pathogenicity in the blast fungus. Our studies uncovered a novel intracellular reactive oxygen species signal-transducing mechanism in a model pathogenic fungus with important basic and applied implications.
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Affiliation(s)
- Ruiming Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Xinyu Liu
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Jiayun Xu
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Chen Chen
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Zhaoxuan Tang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Chengtong Wu
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Xinyue Li
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Lei Su
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Muxing Liu
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Leiyun Yang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Gang Li
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Haifeng Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Ping Wang
- Department of Microbiology, Immunology, and Parasitology, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
| | - Zhengguang Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
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Ding Y, Ma N, Haseeb HA, Dai Z, Zhang J, Guo W. Genome-wide transcriptome analysis of toxigenic Fusarium verticillioides in response to variation of temperature and water activity on maize kernels. Int J Food Microbiol 2024; 410:110494. [PMID: 38006847 DOI: 10.1016/j.ijfoodmicro.2023.110494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 11/08/2023] [Accepted: 11/13/2023] [Indexed: 11/27/2023]
Abstract
Fusarium verticillioides is one of the important mycotoxigenic pathogens of maize since it causes severe yield losses and produces fumonisins (FBs) to threaten human and animal health. Previous studies showed that temperature and water activity (aw) are two pivotal environmental factors affecting F. verticillioides growth and FBs production during maize storage. However, the genome-wide transcriptome analysis of differentially expressed genes (DEGs) in F. verticillioides under the stress combinations of temperature and aw has not been studied in detail. In this study, DEGs of F. verticillioides and their related regulatory pathways were analyzed in response to the stress of temperature and aw combinations using RNA-Seq. The results showed that the optimal growth conditions for F. verticillioides were 0.98 aw and 25 °C, whereas the highest per-unit yield of the fumonisin B1 (FB1) was observed at 0.98 aw and 15 °C. The RNA-seq analysis showed that 9648 DEGs were affected by temperature regardless of aw levels, whereas only 218 DEGs were affected by aw regardless of temperature variations. Gene Ontology (GO) analysis revealed that a decrease in temperature at both aw levels led to a significant upregulation of genes associated with 24 biological processes, while three biological processes were downregulated. Furthermore, when aw was decreased at both temperatures, seven biological processes were significantly upregulated and four were downregulated. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis revealed that the genes, whose expression was upregulated when the temperature decreased, were predominantly associated with the proteasome pathway, whereas the genes, whose expression was downregulated when the aw decreased, were mainly linked to amino acid metabolism. For the FB1, except for the FUM15 gene, the other 15 biosynthetic-related genes were highly expressed at 0.98 aw and 15 °C. In addition, the expression pattern analysis of other biosynthetic genes involved in secondary metabolite production and regulation of fumonisins production was conducted to explore how this fungus responds to the stress combinations of temperature and aw. Overall, this study primarily examines the impact of temperature and aw on the growth of F. verticillioides and its production of FB1 using transcriptome data. The findings presented here have the potential to contribute to the development of novel strategies for managing fungal diseases and offer valuable insights for preventing fumonisin contamination in food and feed storage.
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Affiliation(s)
- Yi Ding
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences/Key Laboratory of Agro-products Quality and Safety Control in Storage and Transport Process, Ministry of Agriculture and Rural Affairs, Beijing 100193, PR China
| | - Nini Ma
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences/Key Laboratory of Agro-products Quality and Safety Control in Storage and Transport Process, Ministry of Agriculture and Rural Affairs, Beijing 100193, PR China
| | - Hafiz Abdul Haseeb
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences/Key Laboratory of Agro-products Quality and Safety Control in Storage and Transport Process, Ministry of Agriculture and Rural Affairs, Beijing 100193, PR China; Directorate General of Pest Warning and Quality Control of Pesticides, Punjab, Lahore, Pakistan
| | - Zhaoji Dai
- Sanya Nanfan Research Institute, Key Laboratory of Green Prevention and Control of Tropical Plant Diseases and Pests (Ministry of Education), School of Plant Protection, Hainan University, Haikou, Hainan 570228, PR China
| | - Jun Zhang
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences/Key Laboratory of Agro-products Quality and Safety Control in Storage and Transport Process, Ministry of Agriculture and Rural Affairs, Beijing 100193, PR China
| | - Wei Guo
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences/Key Laboratory of Agro-products Quality and Safety Control in Storage and Transport Process, Ministry of Agriculture and Rural Affairs, Beijing 100193, PR China.
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Xu J, Liu X, Zhang W, Feng W, Liu M, Yang L, Yang Z, Zhang H, Zhang Z, Wang P. Hydrophobic cue-induced appressorium formation depends on MoSep1-mediated MoRgs7 phosphorylation and internalization in Magnaporthe oryzae. PLoS Genet 2023; 19:e1010748. [PMID: 37186579 PMCID: PMC10184898 DOI: 10.1371/journal.pgen.1010748] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 04/16/2023] [Indexed: 05/17/2023] Open
Abstract
The rice blast fungus Magnaporthe oryzae forms specialized infectious structures called appressoria that breach host cells to initiate infection. Previous studies demonstrated that the regulator of G-protein signaling (RGS)-like protein MoRgs7 undergoes endocytosis upon fungal sensing of hydrophobic environmental cues to activate cAMP signaling required for appressorium formation. However, the mechanism by which MoRgs7 internalizes and its fate remains undetermined. We here show that MoSep1, a conserved protein kinase of Mitotic Exit Network (MEN), phosphorylates MoRgs7 to regulate its function. MoRgs7 phosphorylation determines its interaction with MoCrn1, a coronin-like actin-binding protein homolog that also modulates the internalization of MoRgs7. Importantly, the endocytic transport of MoRgs7 is critical for its GTPase-activating protein (GAP) function important in cAMP signaling. Together, our findings revealed a novel mechanism by which M. oryzae activates MoRgs7-mediated hydrophobic cue-sensing signal transduction involving protein phosphorylation and endocytic transport to govern appressorium formation and fungal pathogenicity.
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Affiliation(s)
- Jiayun Xu
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, China
| | - Xinyu Liu
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, China
| | - Wei Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, China
| | - Wanzhen Feng
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, China
| | - Muxing Liu
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, China
| | - Leiyun Yang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, China
| | - Zhixiang Yang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, China
| | - Haifeng Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, China
| | - Zhengguang Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, China
| | - Ping Wang
- Department of Microbiology, Immunology, and Parasitology, Louisiana State University Health Sciences Center, New Orleans, Louisiana, United States of America
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Yang Y, Huang P, Ma Y, Jiang R, Jiang C, Wang G. Insights into intracellular signaling network in Fusarium species. Int J Biol Macromol 2022; 222:1007-1014. [PMID: 36179869 DOI: 10.1016/j.ijbiomac.2022.09.211] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 09/23/2022] [Indexed: 11/27/2022]
Abstract
Fusarium is a large genus of filamentous fungi including numerous important plant pathogens. In addition to causing huge economic losses of crops, some Fusarium species produce a wide range of mycotoxins in cereal crops that affect human and animal health. The intracellular signaling in Fusarium plays an important role in growth, sexual and asexual developments, pathogenesis, and mycotoxin biosynthesis. In this review, we highlight the recent advances and provide insight into signal sensing and transduction in Fusarium species. G protein-coupled receptors and other conserved membrane receptors mediate recognition of environmental cues and activate complex intracellular signaling. Once activated, the cAMP-PKA and three well-conserved MAP kinase pathways activate downstream transcriptional regulatory networks. The functions of individual signaling pathways have been well characterized in a variety of Fusarium species, showing the conserved components with diverged functions. Furthermore, these signaling pathways crosstalk and coordinately regulate various fungal development and infection-related morphogenesis.
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Affiliation(s)
- Yang Yang
- State Key Laboratory of Crop Stress Biology for Arid areas, Northwestern A&F University, Yangling, Shaanxi 712100, China
| | - Panpan Huang
- State Key Laboratory of Crop Stress Biology for Arid areas, Northwestern A&F University, Yangling, Shaanxi 712100, China
| | - Yutong Ma
- State Key Laboratory of Crop Stress Biology for Arid areas, Northwestern A&F University, Yangling, Shaanxi 712100, China
| | - Ruoxuan Jiang
- State Key Laboratory of Crop Stress Biology for Arid areas, Northwestern A&F University, Yangling, Shaanxi 712100, China
| | - Cong Jiang
- State Key Laboratory of Crop Stress Biology for Arid areas, Northwestern A&F University, Yangling, Shaanxi 712100, China.
| | - Guanghui Wang
- State Key Laboratory of Crop Stress Biology for Arid areas, Northwestern A&F University, Yangling, Shaanxi 712100, China.
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Zhang H, Kim MS, Huang J, Yan H, Yang T, Song L, Yu W, Shim WB. Transcriptome analysis of maize pathogen Fusarium verticillioides revealed FvLcp1, a secreted protein with type-D fungal LysM and chitin-binding domains, that plays important roles in pathogenesis and mycotoxin production. Microbiol Res 2022; 265:127195. [PMID: 36126492 DOI: 10.1016/j.micres.2022.127195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 08/21/2022] [Accepted: 09/07/2022] [Indexed: 11/15/2022]
Abstract
Fusarium verticillioides is a key maize pathogen and produces fumonisins, a group of mycotoxins detrimental to humans and animals. Unfortunately, our understanding on how this fungus interacts with maize to trigger mycotoxin biosynthesis is limited. We performed a systematic computational network-based analysis of large-scale F. verticillioides RNA-seq datasets to identify gene subnetwork modules associated with virulence and fumonisin regulation. F. verticillioides was inoculated on two different maize lines, moderately resistant line hybrid 33K44 and highly susceptible line maize inbred line B73, to generate time-course RNA-Seq data. Among the highly discriminative subnetwork modules, we identified a putative hub gene FvLCP1, which encodes a putative a type-D fungal LysM protein with a signal peptide, three LysM domains, and two chitin binding domains. FvLcp1 is a unique protein that harbors these domains amongst five representative Fusarium species. FvLcp1 is a secreted protein important for fumonisin production with the LysM domain playing a critical role. The chitin-binding domain was essential for in vitro chitin binding. Using Magnaporthe oryzae, we learned that FvLcp1 accumulates in appressoria, suggesting that FvLcp1 is involved in host recognition and infection. Full length FvLcp1 suppressed BAX-triggered plant cell death in Nicotiana benthamiana. This unique type-D LysM secreted protein with a chitin-binding domain in F. verticillioides was shown to be potentially involved in suppressing host cell death and promoting fumonisin biosynthesis while the pathogen colonizes maize kernels.
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Affiliation(s)
- Huan Zhang
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843-2132, USA.
| | - Man S Kim
- Clinical Research Institute, Kyung Hee University Hospital at Gangdong, College of Medicine, Kyung Hee University, Seoul, South Korea
| | - Jun Huang
- Fujian University Key Laboratory for Functional Genomics of Plant Fungal Pathogens, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Huijuan Yan
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843-2132, USA
| | - Tao Yang
- Fujian University Key Laboratory for Functional Genomics of Plant Fungal Pathogens, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Linlin Song
- Fujian University Key Laboratory for Functional Genomics of Plant Fungal Pathogens, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Wenying Yu
- Fujian University Key Laboratory for Functional Genomics of Plant Fungal Pathogens, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Won Bo Shim
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843-2132, USA.
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Ma N, Zhao Y, Wang Y, Yang L, Li D, Yang J, Jiang K, Zhang KQ, Yang J. Functional analysis of seven regulators of G protein signaling (RGSs) in the nematode-trapping fungus Arthrobotrys oligospora. Virulence 2021; 12:1825-1840. [PMID: 34224331 PMCID: PMC8259722 DOI: 10.1080/21505594.2021.1948667] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 06/06/2021] [Accepted: 06/18/2021] [Indexed: 01/09/2023] Open
Abstract
Regulators of G protein signaling (RGSs) are proteins that negatively regulate G protein signal transduction. In this study, seven putative RGSs were characterized in the nematode-trapping (NT) fungus, Arthrobotrys oligospora. Deleting Rgs genes significantly increased intracellular cAMP levels, and caused defects in mycelia growth, stress resistance, conidiation, trap formation, and nematocidal activity. In particular, the ΔAoFlbA mutant was unable to produce conidia and traps. Transcriptomic analysis showed that amino acid metabolic and biosynthetic processes were significantly enriched in the ΔAoFlbA mutant compared to WT. Interestingly, Gas1 family genes are significantly expanded in A. oligospora and other NT fungi that produce adhesive traps, and are differentially expressed during trap formation in A. oligospora. Disruption of two Gas1 genes resulted in defective conidiation, trap formation, and pathogenicity. Our results indicate that RGSs play pleiotropic roles in regulating A. oligospora mycelial growth, development, and pathogenicity. Further, AoFlbA is a prominent member and required for conidiation and trap formation, possibly by regulating amino acid metabolism and biosynthesis. Our results provide a basis for elucidating the signaling mechanism of vegetative growth, lifestyle transition, and pathogenicity in NT fungi.
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Affiliation(s)
- Ni Ma
- State Key Laboratory for Conservation and Utilization of Bio-Resources, and Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, KunmingP. R. China
- School of Life Sciences, Yunnan University, KunmingP. R. China
| | - Yining Zhao
- State Key Laboratory for Conservation and Utilization of Bio-Resources, and Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, KunmingP. R. China
- School of Life Sciences, Yunnan University, KunmingP. R. China
| | - Yunchuan Wang
- State Key Laboratory for Conservation and Utilization of Bio-Resources, and Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, KunmingP. R. China
- Institute of Medical Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, KunmingP. R. China
| | - Le Yang
- State Key Laboratory for Conservation and Utilization of Bio-Resources, and Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, KunmingP. R. China
- School of Life Sciences, Yunnan University, KunmingP. R. China
| | - Dongni Li
- State Key Laboratory for Conservation and Utilization of Bio-Resources, and Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, KunmingP. R. China
- School of Life Sciences, Yunnan University, KunmingP. R. China
| | - Jiangliu Yang
- State Key Laboratory for Conservation and Utilization of Bio-Resources, and Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, KunmingP. R. China
- School of Life Sciences, Yunnan University, KunmingP. R. China
| | - Kexin Jiang
- State Key Laboratory for Conservation and Utilization of Bio-Resources, and Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, KunmingP. R. China
- School of Life Sciences, Yunnan University, KunmingP. R. China
| | - Ke-Qin Zhang
- State Key Laboratory for Conservation and Utilization of Bio-Resources, and Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, KunmingP. R. China
- School of Life Sciences, Yunnan University, KunmingP. R. China
| | - Jinkui Yang
- State Key Laboratory for Conservation and Utilization of Bio-Resources, and Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, KunmingP. R. China
- School of Life Sciences, Yunnan University, KunmingP. R. China
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Park YS, Borrego EJ, Gao X, Christensen SA, Schmelz E, Lanubile A, Drab DA, Cody W, Yan H, Shim WB, Kolomiets MV. Fusarium verticillioides Induces Maize-Derived Ethylene to Promote Virulence by Engaging Fungal G-Protein Signaling. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2021; 34:1157-1166. [PMID: 34165327 DOI: 10.1094/mpmi-09-20-0250-r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Seed maceration and contamination with mycotoxin fumonisin inflicted by Fusarium verticillioides is a major disease concern for maize producers worldwide. Meta-analyses of quantitative trait loci for Fusarium ear rot resistance uncovered several ethylene (ET) biosynthesis and signaling genes within them, implicating ET in maize interactions with F. verticillioides. We tested this hypothesis using maize knockout mutants of the 1-aminocyclopropane-1-carboxylate (ACC) synthases ZmACS2 and ZmACS6. Infected wild-type seed emitted five-fold higher ET levels compared with controls, whereas ET was abolished in the acs2 and acs6 single and double mutants. The mutants supported reduced fungal biomass, conidia, and fumonisin content. Normal susceptibility was restored in the acs6 mutant with exogenous treatment of ET precursor ACC. Subsequently, we showed that fungal G-protein signaling is required for virulence via induction of maize-produced ET. F. verticillioides Gβ subunit and two regulators of G-protein signaling mutants displayed reduced seed colonization and decreased ET levels. These defects were rescued by exogenous application of ACC. We concluded that pathogen-induced ET facilitates F. verticillioides colonization of seed, and, in turn, host ET production is manipulated via G-protein signaling of F. verticillioides to facilitate pathogenesis.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Yong-Soon Park
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843-2132, U.S.A
| | - Eli J Borrego
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843-2132, U.S.A
| | - Xiquan Gao
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843-2132, U.S.A
| | - Shawn A Christensen
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843-2132, U.S.A
- Chemistry Unit, Center of Medical, Agricultural, and Veterinary Entomology, United States Department of Agriculture, Gainesville, FL 32608, U.S.A
| | - Eric Schmelz
- Chemistry Unit, Center of Medical, Agricultural, and Veterinary Entomology, United States Department of Agriculture, Gainesville, FL 32608, U.S.A
| | - Alessandra Lanubile
- Department of Sustainable Crop Production, Università Cattolica del Sacro Cuore, Piacenza, Italy
| | - Dillon A Drab
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843-2132, U.S.A
| | - Will Cody
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843-2132, U.S.A
| | - Huijuan Yan
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843-2132, U.S.A
| | - Won-Bo Shim
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843-2132, U.S.A
| | - Michael V Kolomiets
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843-2132, U.S.A
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Yan H, Zhou Z, Shim WB. Two regulators of G-protein signaling (RGS) proteins FlbA1 and FlbA2 differentially regulate fumonisin B1 biosynthesis in Fusarium verticillioides. Curr Genet 2021; 67:305-315. [PMID: 33392742 DOI: 10.1007/s00294-020-01140-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 11/23/2020] [Accepted: 11/30/2020] [Indexed: 11/28/2022]
Abstract
Fumonisins are a group of mycotoxins produced by maize pathogen Fusarium verticillioides that pose health concerns to humans and animals. Yet we still lack a clear understanding of the mechanism of fumonisins regulation during pathogenesis. The heterotrimeric G protein complex, which consists of canonical subunits and various regulators of G-protein signaling (RGS) proteins, plays an important role in transducing signals under environmental stress. Earlier studies demonstrated that Gα and Gβ subunits are positive regulators of fumonisin B1 (FB1) biosynthesis and that two RGS genes, FvFlbA1 and FvFlbA2, were highly upregulated in Gβ deletion mutant ∆Fvgbb1. Notably, FvFlbA2 has a negative role in FB1 regulation. While many fungi contain a single copy of FlbA, F. verticillioides harbors two putative FvFlbA paralogs, FvFlbA1 and FvFlbA2. In this study, we further characterized functional roles of FvFlbA1 and FvFlbA2. While ∆FvflbA1 deletion mutant exhibited no significant defects, ∆FvflbA2 and ∆FvflbA2/A1 mutants showed thinner aerial hyphal growth while promoting FB1 production. FvFlbA2 is required for proper expression of key conidia regulation genes, including putative FvBRLA, FvWETA, and FvABAA, while suppressing FUM21, FUM1, and FUM8 expression. Split luciferase assays determined that FvFlbA paralogs interact with key heterotrimeric G protein components, which in turn will lead altered G-protein-mediated signaling pathways that regulate FB1 production and asexual development in F. verticillioides.
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Affiliation(s)
- Huijuan Yan
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX, 77843, USA
| | - Zehua Zhou
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX, 77843, USA.,College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China
| | - Won Bo Shim
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX, 77843, USA.
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9
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Samayoa LF, Cao A, Santiago R, Malvar RA, Butrón A. Genome-wide association analysis for fumonisin content in maize kernels. BMC PLANT BIOLOGY 2019; 19:166. [PMID: 31029090 PMCID: PMC6486958 DOI: 10.1186/s12870-019-1759-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 04/04/2019] [Indexed: 05/19/2023]
Abstract
BACKGROUND Plant breeding has been proposed as one of the most effective and environmentally safe methods to control fungal infection and to reduce fumonisin accumulation. However, conventional breeding can be hampered by the complex genetic architecture of resistance to fumonisin accumulation and marker-assisted selection is proposed as an efficient alternative. In the current study, GWAS has been performed for the first time for detecting high-resolution QTL for resistance to fumonisin accumulation in maize kernels complementing published GWAS results for Fusarium ear rot. RESULTS Thirty-nine SNPs significantly associated with resistance to fumonisin accumulation in maize kernels were found and clustered into 17 QTL. Novel QTLs for fumonisin content would be at bins 3.02, 5.02, 7.05 and 8.07. Genes with annotated functions probably implicated in resistance to pathogens based on previous studies have been highlighted. CONCLUSIONS Breeding approaches to fix favorable functional variants for genes implicated in maize immune response signaling may be especially useful to reduce kernel contamination with fumonisins without significantly interfering in mycelia development and growth and, consequently, in the beneficial endophytic behavior of Fusarium verticillioides.
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Affiliation(s)
- L. F. Samayoa
- Misión Biológica de Galicia (MBG - CSIC), Box 28, 36080 Pontevedra, Spain
- Present address at department of Crop Science, North Carolina State University, Raleigh, NC 27695 USA
| | - A. Cao
- Misión Biológica de Galicia (MBG - CSIC), Box 28, 36080 Pontevedra, Spain
- Facultad de Biología, Department Biología Vegetal y Ciencias del Suelo, Universidad de Vigo, As Lagoas Marcosende, 36310 Vigo, Spain
- Agrobiología Ambiental, Calidad de Suelos y Plantas (BVE1-UVIGO), Unidad Asociada a la MBG – CSIC, 36143 Pontevedra, Spain
| | - R. Santiago
- Facultad de Biología, Department Biología Vegetal y Ciencias del Suelo, Universidad de Vigo, As Lagoas Marcosende, 36310 Vigo, Spain
- Agrobiología Ambiental, Calidad de Suelos y Plantas (BVE1-UVIGO), Unidad Asociada a la MBG – CSIC, 36143 Pontevedra, Spain
| | - R. A. Malvar
- Misión Biológica de Galicia (MBG - CSIC), Box 28, 36080 Pontevedra, Spain
- Agrobiología Ambiental, Calidad de Suelos y Plantas (BVE1-UVIGO), Unidad Asociada a la MBG – CSIC, 36143 Pontevedra, Spain
| | - A. Butrón
- Misión Biológica de Galicia (MBG - CSIC), Box 28, 36080 Pontevedra, Spain
- Agrobiología Ambiental, Calidad de Suelos y Plantas (BVE1-UVIGO), Unidad Asociada a la MBG – CSIC, 36143 Pontevedra, Spain
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10
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Battilani P, Lanubile A, Scala V, Reverberi M, Gregori R, Falavigna C, Dall'asta C, Park Y, Bennett J, Borrego EJ, Kolomiets MV. Oxylipins from both pathogen and host antagonize jasmonic acid-mediated defence via the 9-lipoxygenase pathway in Fusarium verticillioides infection of maize. MOLECULAR PLANT PATHOLOGY 2018; 19:2162-2176. [PMID: 29660236 PMCID: PMC6638020 DOI: 10.1111/mpp.12690] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 03/22/2018] [Accepted: 04/08/2018] [Indexed: 05/29/2023]
Abstract
Oxylipins are a newly emerging group of signals that serve defence roles or promote virulence. To identify specific host and fungal genes and oxylipins governing the interactions between maize and Fusarium verticillioides, maize wild-type and lipoxygenase3 (lox3) mutant were inoculated with either F. verticillioides wild-type or linoleate-diol-synthase 1-deleted mutant (ΔFvlds1D). The results showed that lox3 mutants were more resistant to F. verticillioides. The reduced colonization on lox3 was associated with reduced fumonisin production and with a stronger and earlier induction of ZmLOX4, ZmLOX5 and ZmLOX12. In addition to the reported defence function of ZmLOX12, we showed that lox4 and lox5 mutants were more susceptible to F. verticillioides and possessed decreased jasmonate levels during infection, suggesting that these genes are essential for jasmonic acid (JA)-mediated defence. Oxylipin profiling revealed a dramatic reduction in fungal linoleate diol synthase 1 (LDS1)-derived oxylipins, especially 8-HpODE (8-hydroperoxyoctadecenoic acid), in infected lox3 kernels, indicating the importance of this molecule in virulence. Collectively, we make the following conclusions: (1) LOX3 is a major susceptibility factor induced by fungal LDS1-derived oxylipins to suppress JA-stimulating 9-LOXs; (2) LOX3-mediated signalling promotes the biosynthesis of virulence-promoting oxylipins in the fungus; and (3) both fungal LDS1- and host LOX3-produced oxylipins are essential for the normal infection and colonization processes of maize seed by F. verticillioides.
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Affiliation(s)
- Paola Battilani
- Department of Sustainable Crop ProductionUniversità Cattolica del Sacro Cuore29122 PiacenzaItaly
| | - Alessandra Lanubile
- Department of Sustainable Crop ProductionUniversità Cattolica del Sacro Cuore29122 PiacenzaItaly
| | - Valeria Scala
- CREA‐DC, Consiglio per la Ricerca in Agricoltura e l'Analisi dell'Economia Agraria, Research Center for Plant Protection and Certification00156 RomeItaly
| | - Massimo Reverberi
- Department of Environmental BiologyUniversity of Rome “Sapienza”00165 RomeItaly
| | - Rossella Gregori
- Department of Sustainable Crop ProductionUniversità Cattolica del Sacro Cuore29122 PiacenzaItaly
| | - Claudia Falavigna
- Department of Organic and Industrial ChemistryUniversity of Parma43124 ParmaItaly
| | - Chiara Dall'asta
- Department of Organic and Industrial ChemistryUniversity of Parma43124 ParmaItaly
| | - Yong‐Soon Park
- BK21 plus program, College of Biological Sciences and BiotechnologyChungnam National UniversityDaejeon 34134South Korea
| | - John Bennett
- Department of Plant Pathology and MicrobiologyTexas A&M University, College StationTX 77843‐2132USA
| | - Eli J. Borrego
- Department of Plant Pathology and MicrobiologyTexas A&M University, College StationTX 77843‐2132USA
| | - Michael V. Kolomiets
- Department of Plant Pathology and MicrobiologyTexas A&M University, College StationTX 77843‐2132USA
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11
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Blacutt AA, Gold SE, Voss KA, Gao M, Glenn AE. Fusarium verticillioides: Advancements in Understanding the Toxicity, Virulence, and Niche Adaptations of a Model Mycotoxigenic Pathogen of Maize. PHYTOPATHOLOGY 2018; 108:312-326. [PMID: 28971734 DOI: 10.1094/phyto-06-17-0203-rvw] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The importance of understanding the biology of the mycotoxigenic fungus Fusarium verticillioides and its various microbial and plant host interactions is critical given its threat to maize, one of the world's most valuable food crops. Disease outbreaks and mycotoxin contamination of grain threaten economic returns and have grave implications for human and animal health and food security. Furthermore, F. verticillioides is a member of a genus of significant phytopathogens and, thus, data regarding its host association, biosynthesis of secondary metabolites, and other metabolic (degradative) capabilities are consequential to both basic and applied research efforts across multiple pathosystems. Notorious among its secondary metabolites are the fumonisin mycotoxins, which cause severe animal diseases and are implicated in human disease. Additionally, studies of these mycotoxins have led to new understandings of F. verticillioides plant pathogenicity and provide tools for research into cellular processes and host-pathogen interaction strategies. This review presents current knowledge regarding several significant lines of F. verticillioides research, including facets of toxin production, virulence, and novel fitness strategies exhibited by this fungus across rhizosphere and plant environments.
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Affiliation(s)
- Alex A Blacutt
- First and fourth authors: Department of Plant Pathology, University of Georgia, Athens 30602; and second, third, and fifth authors: United States Department of Agriculture-Agricultural Research Service, U.S. National Poultry Research Center, Toxicology and Mycotoxin Research Unit, Athens, GA 30605-2720
| | - Scott E Gold
- First and fourth authors: Department of Plant Pathology, University of Georgia, Athens 30602; and second, third, and fifth authors: United States Department of Agriculture-Agricultural Research Service, U.S. National Poultry Research Center, Toxicology and Mycotoxin Research Unit, Athens, GA 30605-2720
| | - Kenneth A Voss
- First and fourth authors: Department of Plant Pathology, University of Georgia, Athens 30602; and second, third, and fifth authors: United States Department of Agriculture-Agricultural Research Service, U.S. National Poultry Research Center, Toxicology and Mycotoxin Research Unit, Athens, GA 30605-2720
| | - Minglu Gao
- First and fourth authors: Department of Plant Pathology, University of Georgia, Athens 30602; and second, third, and fifth authors: United States Department of Agriculture-Agricultural Research Service, U.S. National Poultry Research Center, Toxicology and Mycotoxin Research Unit, Athens, GA 30605-2720
| | - Anthony E Glenn
- First and fourth authors: Department of Plant Pathology, University of Georgia, Athens 30602; and second, third, and fifth authors: United States Department of Agriculture-Agricultural Research Service, U.S. National Poultry Research Center, Toxicology and Mycotoxin Research Unit, Athens, GA 30605-2720
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12
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Yan Q, Zhang Z, Yang Y, Chen F, Shao Y. Proteome analysis reveals global response to deletion of mrflbA in Monascus ruber. J Microbiol 2018; 56:255-263. [DOI: 10.1007/s12275-018-7425-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Revised: 01/09/2018] [Accepted: 01/20/2018] [Indexed: 12/01/2022]
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13
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Xu J, Wang X, Li Y, Zeng J, Wang G, Deng C, Guo W. Host-induced gene silencing of a regulator of G protein signalling gene (VdRGS1) confers resistance to Verticillium wilt in cotton. PLANT BIOTECHNOLOGY JOURNAL 2018; 16:1629-1643. [PMID: 29431919 PMCID: PMC6096726 DOI: 10.1111/pbi.12900] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Accepted: 02/03/2018] [Indexed: 05/20/2023]
Abstract
Verticillium wilt (VW), caused by soil-borne fungi of the genus Verticillium, is a serious disease affecting a wide range of plants and leading to a constant and major challenge to agriculture worldwide. Cotton (Gossypium hirsutum) is the world's most important natural textile fibre and oil crop. VW of cotton is a highly devastating vascular disease; however, few resistant germplasms have been reported in cotton. An increasing number of studies have shown that RNA interference (RNAi)-based host-induced gene silencing (HIGS) is an effective strategy for improving plant resistance to pathogens by silencing genes essential for the pathogenicity of these pathogens. Here, we have identified and characterized multifunctional regulators of G protein signalling (RGS) in the Verticillium dahliae virulence strain, Vd8. Of eight VdRGS genes, VdRGS1 showed the most significant increase in expression in V. dahliae after treating with the roots of cotton seedlings. Based on the phenotype detection of VdRGS1 deletion and complementation mutants, we found that VdRGS1 played crucial roles in spore production, hyphal development, microsclerotia formation and pathogenicity. Tobacco rattle virus-mediated HIGS in cotton plants silenced VdRGS1 transcripts in invaded V. dahliae strains and enhanced broad-spectrum resistance to cotton VW. Our data demonstrate that VdRGS1 is a conserved and essential gene for V. dahliae virulence. HIGS of VdRGS1 provides effective control against V. dahliae infection and could obtain the durable disease resistance in cotton and in other VW-susceptible host crops by developing the stable transformants.
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Affiliation(s)
- Jun Xu
- State Key Laboratory of Crop Genetics & Germplasm EnhancementNanjing Agricultural UniversityNanjingJiangsuChina
| | - Xinyu Wang
- College of Life SciencesNanjing Agricultural UniversityNanjingJiangsuChina
| | - Yongqing Li
- State Key Laboratory of Crop Genetics & Germplasm EnhancementNanjing Agricultural UniversityNanjingJiangsuChina
| | - Jianguo Zeng
- College of Life SciencesNanjing Agricultural UniversityNanjingJiangsuChina
| | - Guilin Wang
- State Key Laboratory of Crop Genetics & Germplasm EnhancementNanjing Agricultural UniversityNanjingJiangsuChina
| | - Chaoyang Deng
- State Key Laboratory of Crop Genetics & Germplasm EnhancementNanjing Agricultural UniversityNanjingJiangsuChina
| | - Wangzhen Guo
- State Key Laboratory of Crop Genetics & Germplasm EnhancementNanjing Agricultural UniversityNanjingJiangsuChina
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14
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Functional analysis of a regulator of G-protein signaling CgRGS1 in the rubber tree anthracnose fungus Colletotrichum gloeosporioides. Arch Microbiol 2017; 200:391-400. [PMID: 29177869 DOI: 10.1007/s00203-017-1455-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2017] [Revised: 11/12/2017] [Accepted: 11/14/2017] [Indexed: 01/02/2023]
Abstract
Colletotrichum gloeosporioides is the causal agent of rubber anthracnose, which is also one of the important biological factors threatening the development of natural rubber industry in the world. Regulators of G-protein signaling (RGS) are key negative regulators of G-proteins, which play important roles in growth, development and pathogenic processes of plant pathogens. In this study, a RGS gene CgRGS1 was functionally characterized in C. gloeosporioides. Compared to the wild type, the CgRGS1 deletion mutant had slow vegetative growth, reduced conidia with multi-end germination, low appressorium formation rate, high resistance to oxidative stress and SDS. Moreover, the mutant was sensitive to osmotic pressure and showed decreased virulence. In conclusion, CgRGS1 is involved in regulation of vegetative growth, conidiation, germination, appressorium formation, oxidative stress, osmotic pressure response and pathogenicity in C. gloeosporioides.
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15
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Moretti M, Wang L, Grognet P, Lanver D, Link H, Kahmann R. Three regulators of G protein signaling differentially affect mating, morphology and virulence in the smut fungusUstilago maydis. Mol Microbiol 2017; 105:901-921. [DOI: 10.1111/mmi.13745] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/06/2017] [Indexed: 12/30/2022]
Affiliation(s)
- Marino Moretti
- Department of Organismic Interactions; Max Planck Institute for Terrestrial Microbiology; Karl-von-Frisch-Strasse 10, Marburg D-35043 Germany
| | - Lei Wang
- Department of Organismic Interactions; Max Planck Institute for Terrestrial Microbiology; Karl-von-Frisch-Strasse 10, Marburg D-35043 Germany
| | - Pierre Grognet
- Department of Organismic Interactions; Max Planck Institute for Terrestrial Microbiology; Karl-von-Frisch-Strasse 10, Marburg D-35043 Germany
| | - Daniel Lanver
- Department of Organismic Interactions; Max Planck Institute for Terrestrial Microbiology; Karl-von-Frisch-Strasse 10, Marburg D-35043 Germany
| | - Hannes Link
- Dynamic Control of Metabolic Networks; Max Planck Institute for Terrestrial Microbiology; Karl-von-Frisch-Strasse 16, Marburg D-35043 Germany
| | - Regine Kahmann
- Department of Organismic Interactions; Max Planck Institute for Terrestrial Microbiology; Karl-von-Frisch-Strasse 10, Marburg D-35043 Germany
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16
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Ridenour JB, Bluhm BH. The novel fungal-specific gene FUG1 has a role in pathogenicity and fumonisin biosynthesis in Fusarium verticillioides. MOLECULAR PLANT PATHOLOGY 2017; 18:513-528. [PMID: 27071505 PMCID: PMC6638258 DOI: 10.1111/mpp.12414] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2016] [Revised: 04/06/2016] [Accepted: 04/07/2016] [Indexed: 05/05/2023]
Abstract
Fusarium verticillioides is a globally important pathogen of maize, capable of causing severe yield reductions and economic losses. In addition, F. verticillioides produces toxic secondary metabolites during kernel colonization that pose significant threats to human and animal health. Fusarium verticillioides and other plant-pathogenic fungi possess a large number of genes with no known or predicted function, some of which could encode novel virulence factors or antifungal targets. In this study, we identified and characterized the novel gene FUG1 (Fungal Unknown Gene 1) in F. verticillioides through functional genetics. Deletion of FUG1 impaired maize kernel colonization and fumonisin biosynthesis. In addition, deletion of FUG1 increased sensitivity to the antimicrobial compound 2-benzoxazolinone and to hydrogen peroxide, which indicates that FUG1 may play a role in mitigating stresses associated with host defence. Transcriptional profiling via RNA-sequencing (RNA-seq) identified numerous fungal genes that were differentially expressed in the kernel environment following the deletion of FUG1, including genes involved in secondary metabolism and mycelial development. Sequence analysis of the Fug1 protein provided evidence for nuclear localization, DNA binding and a domain of unknown function associated with previously characterized transcriptional regulators. This information, combined with the observed transcriptional reprogramming in the deletion mutant, suggests that FUG1 represents a novel class of fungal transcription factors or genes otherwise involved in signal transduction.
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Affiliation(s)
- John B. Ridenour
- Department of Plant PathologyUniversity of Arkansas Division of AgricultureFayettevilleAR 72701USA
| | - Burton H. Bluhm
- Department of Plant PathologyUniversity of Arkansas Division of AgricultureFayettevilleAR 72701USA
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17
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Ridenour JB, Smith JE, Bluhm BH. The HAP Complex Governs Fumonisin Biosynthesis and Maize Kernel Pathogenesis in Fusarium verticillioides. J Food Prot 2016; 79:1498-1507. [PMID: 28221941 DOI: 10.4315/0362-028x.jfp-15-596] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Contamination of maize ( Zea mays ) with fumonisins produced by the fungus Fusarium verticillioides is a global concern for food safety. Fumonisins are a group of polyketide-derived secondary metabolites linked to esophageal cancer and neural tube birth defects in humans and numerous toxicoses in livestock. Despite the importance of fumonisins in global maize production, the regulation of fumonisin biosynthesis during kernel pathogenesis is poorly understood. The HAP complex is a conserved, heterotrimeric transcriptional regulator that binds the consensus sequence CCAAT to modulate gene expression. Recently, functional characterization of the Hap3 subunit linked the HAP complex to the regulation of secondary metabolism and stalk rot pathogenesis in F. verticillioides . Here, we determine the involvement of HAP3 in fumonisin biosynthesis and kernel pathogenesis. Deletion of HAP3 suppressed fumonisin biosynthesis on both nonviable and live maize kernels and impaired pathogenesis in living kernels. Transcriptional profiling via RNA sequencing indicated that the HAP complex regulates at least 1,223 genes in F. verticillioides , representing nearly 10% of all predicted genes. Disruption of the HAP complex caused the misregulation of biosynthetic gene clusters underlying the production of secondary metabolites, including fusarins. Taken together, these results reveal that the HAP complex is a central regulator of fumonisin biosynthesis and kernel pathogenesis and works as both a positive and negative regulator of secondary metabolism in F. verticillioides .
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Affiliation(s)
- John B Ridenour
- Department of Plant Pathology, Division of Agriculture, University of Arkansas, Fayetteville, Arkansas 72701, USA
| | - Jonathon E Smith
- Department of Plant Pathology, Division of Agriculture, University of Arkansas, Fayetteville, Arkansas 72701, USA
| | - Burton H Bluhm
- Department of Plant Pathology, Division of Agriculture, University of Arkansas, Fayetteville, Arkansas 72701, USA
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18
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Schmoll M, Dattenböck C, Carreras-Villaseñor N, Mendoza-Mendoza A, Tisch D, Alemán MI, Baker SE, Brown C, Cervantes-Badillo MG, Cetz-Chel J, Cristobal-Mondragon GR, Delaye L, Esquivel-Naranjo EU, Frischmann A, Gallardo-Negrete JDJ, García-Esquivel M, Gomez-Rodriguez EY, Greenwood DR, Hernández-Oñate M, Kruszewska JS, Lawry R, Mora-Montes HM, Muñoz-Centeno T, Nieto-Jacobo MF, Nogueira Lopez G, Olmedo-Monfil V, Osorio-Concepcion M, Piłsyk S, Pomraning KR, Rodriguez-Iglesias A, Rosales-Saavedra MT, Sánchez-Arreguín JA, Seidl-Seiboth V, Stewart A, Uresti-Rivera EE, Wang CL, Wang TF, Zeilinger S, Casas-Flores S, Herrera-Estrella A. The Genomes of Three Uneven Siblings: Footprints of the Lifestyles of Three Trichoderma Species. Microbiol Mol Biol Rev 2016; 80:205-327. [PMID: 26864432 PMCID: PMC4771370 DOI: 10.1128/mmbr.00040-15] [Citation(s) in RCA: 121] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The genus Trichoderma contains fungi with high relevance for humans, with applications in enzyme production for plant cell wall degradation and use in biocontrol. Here, we provide a broad, comprehensive overview of the genomic content of these species for "hot topic" research aspects, including CAZymes, transport, transcription factors, and development, along with a detailed analysis and annotation of less-studied topics, such as signal transduction, genome integrity, chromatin, photobiology, or lipid, sulfur, and nitrogen metabolism in T. reesei, T. atroviride, and T. virens, and we open up new perspectives to those topics discussed previously. In total, we covered more than 2,000 of the predicted 9,000 to 11,000 genes of each Trichoderma species discussed, which is >20% of the respective gene content. Additionally, we considered available transcriptome data for the annotated genes. Highlights of our analyses include overall carbohydrate cleavage preferences due to the different genomic contents and regulation of the respective genes. We found light regulation of many sulfur metabolic genes. Additionally, a new Golgi 1,2-mannosidase likely involved in N-linked glycosylation was detected, as were indications for the ability of Trichoderma spp. to generate hybrid galactose-containing N-linked glycans. The genomic inventory of effector proteins revealed numerous compounds unique to Trichoderma, and these warrant further investigation. We found interesting expansions in the Trichoderma genus in several signaling pathways, such as G-protein-coupled receptors, RAS GTPases, and casein kinases. A particularly interesting feature absolutely unique to T. atroviride is the duplication of the alternative sulfur amino acid synthesis pathway.
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Affiliation(s)
- Monika Schmoll
- Austrian Institute of Technology, Department Health and Environment, Bioresources Unit, Tulln, Austria
| | - Christoph Dattenböck
- Austrian Institute of Technology, Department Health and Environment, Bioresources Unit, Tulln, Austria
| | | | | | - Doris Tisch
- Research Division Biotechnology and Microbiology, Institute of Chemical Engineering, TU Wien, Vienna, Austria
| | - Mario Ivan Alemán
- Cinvestav, Department of Genetic Engineering, Irapuato, Guanajuato, Mexico
| | - Scott E Baker
- Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Christopher Brown
- University of Otago, Department of Biochemistry and Genetics, Dunedin, New Zealand
| | | | - José Cetz-Chel
- LANGEBIO, National Laboratory of Genomics for Biodiversity, Cinvestav-Irapuato, Guanajuato, Mexico
| | | | - Luis Delaye
- Cinvestav, Department of Genetic Engineering, Irapuato, Guanajuato, Mexico
| | | | - Alexa Frischmann
- Research Division Biotechnology and Microbiology, Institute of Chemical Engineering, TU Wien, Vienna, Austria
| | | | - Monica García-Esquivel
- LANGEBIO, National Laboratory of Genomics for Biodiversity, Cinvestav-Irapuato, Guanajuato, Mexico
| | | | - David R Greenwood
- The University of Auckland, School of Biological Sciences, Auckland, New Zealand
| | - Miguel Hernández-Oñate
- LANGEBIO, National Laboratory of Genomics for Biodiversity, Cinvestav-Irapuato, Guanajuato, Mexico
| | - Joanna S Kruszewska
- Polish Academy of Sciences, Institute of Biochemistry and Biophysics, Laboratory of Fungal Glycobiology, Warsaw, Poland
| | - Robert Lawry
- Lincoln University, Bio-Protection Research Centre, Lincoln, Canterbury, New Zealand
| | | | | | | | | | | | | | - Sebastian Piłsyk
- Polish Academy of Sciences, Institute of Biochemistry and Biophysics, Laboratory of Fungal Glycobiology, Warsaw, Poland
| | - Kyle R Pomraning
- Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Aroa Rodriguez-Iglesias
- Austrian Institute of Technology, Department Health and Environment, Bioresources Unit, Tulln, Austria
| | | | | | - Verena Seidl-Seiboth
- Research Division Biotechnology and Microbiology, Institute of Chemical Engineering, TU Wien, Vienna, Austria
| | | | | | - Chih-Li Wang
- National Chung-Hsing University, Department of Plant Pathology, Taichung, Taiwan
| | - Ting-Fang Wang
- Academia Sinica, Institute of Molecular Biology, Taipei, Taiwan
| | - Susanne Zeilinger
- Research Division Biotechnology and Microbiology, Institute of Chemical Engineering, TU Wien, Vienna, Austria University of Innsbruck, Institute of Microbiology, Innsbruck, Austria
| | | | - Alfredo Herrera-Estrella
- LANGEBIO, National Laboratory of Genomics for Biodiversity, Cinvestav-Irapuato, Guanajuato, Mexico
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19
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The Accordant Trend of Both Parameters (rgs Expression and cAMP Content) Follows the Pattern of Development of Fruiting Body in Volvariella volvacea. Curr Microbiol 2015; 71:579-84. [PMID: 26264785 DOI: 10.1007/s00284-015-0885-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 06/29/2015] [Indexed: 10/23/2022]
Abstract
The formation of fruiting body in Volvariella volvacea is affected by endogenous genes and environmental factors. However, its regulation at a molecular level is still poorly understood. To study the genes involved in the formation of fruiting body, we cloned a new regulator of the G protein signaling (RGS) encoding gene (rgs) from V. volvacea. Phylogenetic analysis showed that RGS in V. volvacea and other basidiomycete RGS proteins from Schizophyllum commune and Coprinus cinereus belong to the same clade. In addition, we assayed intracellular cAMP content in the three developmental stages (mycelium, fruiting body primordia, and button). We also found that the expression of rgs was highly positively correlated to the content of intracellular cAMP during fruiting body formation. The conserved protein sequences and expression of rgs, together with high concent of cAMP at primordia tissue, suggested that rgs gene and cAMP may play a crucial role in fruiting body formation in V. volvacea.
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20
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Wang Y, Geng Z, Jiang D, Long F, Zhao Y, Su H, Zhang KQ, Yang J. Characterizations and functions of regulator of G protein signaling (RGS) in fungi. Appl Microbiol Biotechnol 2013; 97:7977-87. [DOI: 10.1007/s00253-013-5133-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 07/15/2013] [Accepted: 07/16/2013] [Indexed: 12/20/2022]
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Shin KS, Park HS, Kim YH, Yu JH. Comparative proteomic analyses reveal that FlbA down-regulates gliT expression and SOD activity in Aspergillus fumigatus. J Proteomics 2013; 87:40-52. [DOI: 10.1016/j.jprot.2013.05.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Revised: 05/05/2013] [Accepted: 05/09/2013] [Indexed: 10/26/2022]
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Shin JH, Kim JE, Malapi-Wight M, Choi YE, Shaw BD, Shim WB. Protein phosphatase 2A regulatory subunits perform distinct functional roles in the maize pathogen Fusarium verticillioides. MOLECULAR PLANT PATHOLOGY 2013; 14:518-29. [PMID: 23452277 PMCID: PMC6638791 DOI: 10.1111/mpp.12023] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Fusarium verticillioides is a pathogen of maize causing ear rot and stalk rot. The fungus also produces fumonisins, a group of mycotoxins linked to disorders in animals and humans. A cluster of genes, designated FUM genes, plays a key role in the synthesis of fumonisins. However, our understanding of the regulatory mechanism of fumonisin biosynthesis is still incomplete. We have demonstrated previously that Cpp1, a protein phosphatase type 2A (PP2A) catalytic subunit, negatively regulates fumonisin production and is involved in cell shape maintenance. In general, three PP2A subunits, structural A, regulatory B and catalytic C, make up a heterotrimer complex to perform regulatory functions. Significantly, we identified two PP2A regulatory subunits in the F. verticillioides genome, Ppr1 and Ppr2, which are homologous to Saccharomyces cerevisiae Cdc55 and Rts1, respectively. In this study, we hypothesized that Ppr1 and Ppr2 are involved in the regulation of fumonisin biosynthesis and/or cell development in F. verticillioides, and generated a series of mutants to determine the functional role of Ppr1 and Ppr2. The PPR1 deletion strain (Δppr1) resulted in drastic growth defects, but increased microconidia production. The PPR2 deletion mutant strain (Δppr2) showed elevated fumonisin production, similar to the Δcpp1 strain. Germinating Δppr1 conidia formed abnormally swollen cells with a central septation site, whereas Δppr2 showed early hyphal branching during conidia germination. A kernel rot assay showed that the mutants were slow to colonize kernels, but this is probably a result of growth defects rather than a virulence defect. Results from this study suggest that two PP2A regulatory subunits in F. verticillioides carry out distinct roles in the regulation of fumonisin biosynthesis and fungal development.
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Affiliation(s)
- Joon-Hee Shin
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843-2132, USA
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Cao A, Santiago R, Ramos AJ, Marín S, Reid LM, Butrón A. Environmental factors related to fungal infection and fumonisin accumulation during the development and drying of white maize kernels. Int J Food Microbiol 2013; 164:15-22. [PMID: 23587708 DOI: 10.1016/j.ijfoodmicro.2013.03.012] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2012] [Revised: 03/04/2013] [Accepted: 03/14/2013] [Indexed: 10/27/2022]
Abstract
In Southern Europe where whole maize kernels are ground and used for making bread and other food products, infection of the kernels by Fusarium verticillioides and subsequent fumonisin contamination pose a serious safety issue. The influence of environmental factors on this fungal infection and mycotoxin accumulation as the kernel develops has not been fully determined, especially in such food grade maize. The objectives of the present study were to determine which environmental factors may contribute to kernel invasion by F. verticillioides and fumonisin accumulation as kernels develop and dry in naturally infected white maize. Three maize hybrids were planted at two different sowing dates and kernel samples were collected 20, 40, 60, 80 and 100 days after silking. The percentage of kernels infected, and ergosterol and fumonisin contents were recorded for each sampling. F. verticillioides was the most prevalent species identified as the kernels developed. Temperature and moisture conditions during the first 80 days after silking favored natural kernel infection by F. verticillioides rather than by Aspergillus or Penicillium species. Fumonisin was found in kernels as early as 20 days after silking however significant fumonisin accumulation above levels acceptable in the EU did not occur until after physiological maturity of the kernel indicating that kernel drying in the field poses a high risk. Our results suggest that this could be due to increasing kernel damage by insects that favor fungal development, such as the damage by the moth Sitotroga cerealella, and to the occurrence of stress conditions for F. verticillioides growth that could trigger fumonisin biosynthesis, such as exposure to suboptimal temperatures for growth simultaneously with low water activity.
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Affiliation(s)
- Ana Cao
- Misión Biológica de Galicia (CSIC), Apdo. 28, 36080 Pontevedra, Spain
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Ramanujam R, Yishi X, Liu H, Naqvi NI. Structure-function analysis of Rgs1 in Magnaporthe oryzae: role of DEP domains in subcellular targeting. PLoS One 2012; 7:e41084. [PMID: 22927898 PMCID: PMC3426613 DOI: 10.1371/journal.pone.0041084] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Accepted: 06/18/2012] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Rgs1, a prototypical Regulator of G protein Signaling, negatively modulates the cyclic AMP pathway thereby influencing various aspects of asexual development and pathogenesis in the rice-blast fungus Magnaporthe oryzae. Rgs1 possesses tandem DEP motifs (termed DEP-A and DEP-B; for Dishevelled, Egl-10, Pleckstrin) at the N-terminus, and a Gα-GTP interacting RGS catalytic core domain at the C-terminus. In this study, we focused on gaining further insights into the mechanisms of Rgs1 regulation and subcellular localization by characterizing the role(s) of the individual domains and the full-length protein during asexual development and pathogenesis in Magnaporthe. METHODOLOGY/PRINCIPAL FINDINGS Utilizing western blot analysis and specific antisera against the N- and C-terminal halves of Rgs1, we identify and report the in vivo endoproteolytic processing/cleavage of full-length Rgs1 that yields an N-terminal DEP and a RGS core domain. Independent expression of the resultant DEP-DEP half (N-Rgs1) or RGS core (C-Rgs1) fragments, failed to complement the rgs1Δ defects in colony morphology, aerial hyphal growth, surface hydrophobicity, conidiation, appressorium formation and infection. Interestingly, the full-length Rgs1-mCherry, as well as the tagged N-terminal DEP domains (individually or in conjunction) localized to distinct punctate vesicular structures in the cytosol, while the catalytic RGS core motif was predominantly vacuolar. CONCLUSIONS/SIGNIFICANCE Based on our data from sequence alignments, immuno-blot and microscopic analysis, we propose that the post-translational proteolytic processing of Rgs1 and the vacuolar sequestration of the catalytic RGS domain represents an important means of down regulating Rgs1 function and thus forming an additional and alternative means of regulating G protein signaling in Magnaporthe. We further hypothesize the prevalence of analogous mechanisms functioning in other filamentous fungi. Furthermore, we conclusively assign a specific vesicular/membrane targeting function for the N-terminal DEP domains of Rgs1 in the rice-blast fungus.
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Affiliation(s)
- Ravikrishna Ramanujam
- Fungal Patho-Biology Group, Temasek Life Sciences Laboratory, Singapore, Singapore
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Xu Yishi
- Fungal Patho-Biology Group, Temasek Life Sciences Laboratory, Singapore, Singapore
| | - Hao Liu
- MOE Key Laboratory of Industrial Fermentation Microbiology, College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Naweed I. Naqvi
- Fungal Patho-Biology Group, Temasek Life Sciences Laboratory, Singapore, Singapore
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
- * E-mail:
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Horevaj P, Bluhm BH. BDM1, a phosducin-like gene of Fusarium graminearum, is involved in virulence during infection of wheat and maize. MOLECULAR PLANT PATHOLOGY 2012; 13:431-444. [PMID: 22044756 PMCID: PMC6638705 DOI: 10.1111/j.1364-3703.2011.00758.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Fusarium graminearum is a common pathogen of wheat and maize throughout the world. Despite recent advances in the elucidation of the genetic basis of virulence, significant gaps in the regulatory network underlying pathogenesis remain to be filled. In particular, little is known at the molecular level about the overlap among mechanisms of pathogenicity on maize and wheat. G-protein signalling has been implicated in pathogenesis in F. graminearum, although the underlying mechanisms are not fully understood. In this study, we investigated the involvement of a putative phosducin-like gene (BDM1) in growth, development and pathogenesis in F. graminearum. Targeted deletion of BDM1 revealed roles in sexual and asexual sporulation, germ tube development, hyphal branching and mycelial morphology. During pathogenesis, BDM1 is required for wild-type levels of colonization of maize silk tissue and stalks, but is dispensable for the colonization of kernels. The deletion of BDM1 also reduced the virulence of F. graminearum during the infection of wheat seedlings and heads, resulting in a significant reduction in fungal biomass and a delayed spread of visual symptom expression (i.e. bleaching in heads). Furthermore, BDM1 is required for wild-type levels of deoxynivalenol biosynthesis during the infection of wheat heads and maize silks. In summation, BDM1 is one of the few genes characterized to date in F. graminearum involved in virulence during infection of both maize and wheat. Thus, the functional characterization of BDM1 has established a new regulatory link between pathogenesis in maize and wheat, and provides a genetic resource through which the regulatory networks underlying virulence in F. graminearum can be further elucidated.
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Affiliation(s)
- Peter Horevaj
- Department of Plant Pathology, University of Arkansas Division of Agriculture, Fayetteville, AR 72701, USA
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Functional analyses of regulators of G protein signaling in Gibberella zeae. Fungal Genet Biol 2012; 49:511-20. [PMID: 22634273 DOI: 10.1016/j.fgb.2012.05.006] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Revised: 05/08/2012] [Accepted: 05/09/2012] [Indexed: 11/20/2022]
Abstract
Regulators of G protein signaling (RGS) proteins make up a highly diverse and multifunctional protein family that plays a critical role in controlling heterotrimeric G protein signaling. In this study, seven RGS genes (FgFlbA, FgFlbB, FgRgsA, FgRgsB, FgRgsB2, FgRgsC, and FgGprK) were functionally characterized in the plant pathogenic fungus, Gibberella zeae. Mutant phenotypes were observed for deletion mutants of FgRgsA and FgRgsB in vegetative growth, FgFlbB and FgRgsB in conidia morphology, FgFlbA in conidia production, FgFlbA, FgRgsB, and FgRgsC in sexual development, FgFlbA and FgRgsA in spore germination and mycotoxin production, and FgFlbA, FgRgsA, and FgRgsB in virulence. Furthermore, FgFlbA, FgRgsA, and FgRgsB acted pleiotropically, while FgFlbB and FgRgsC deletion mutants exhibited a specific defect in conidia morphology and sexual development, respectively. Amino acid substitutions in Gα subunits and overexpression of the FgFlbA gene revealed that deletion of FgFlbA and dominant active GzGPA2 mutant, gzgpa2(Q207L), had similar phenotypes in cell wall integrity, perithecia formation, mycotoxin production, and virulence, suggesting that FgFlbA may regulate asexual/sexual development, mycotoxin biosynthesis, and virulence through GzGPA2-dependent signaling in G. zeae.
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Christensen S, Borrego E, Shim WB, Isakeit T, Kolomiets M. Quantification of fungal colonization, sporogenesis, and production of mycotoxins using kernel bioassays. J Vis Exp 2012:3727. [PMID: 22546841 PMCID: PMC3578446 DOI: 10.3791/3727] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
The rotting of grains by seed-infecting fungi poses one of the greatest economic challenges to cereal production worldwide, not to mention serious risks to human and animal health. Among cereal production, maize is arguably the most affected crop, due to pathogen-induced losses in grain integrity and mycotoxin seed contamination. The two most prevalent and problematic mycotoxins for maize growers and food and feed processors are aflatoxin and fumonisin, produced by Aspergillus flavus and Fusarium verticillioides, respectively. Recent studies in molecular plant-pathogen interactions have demonstrated promise in understanding specific mechanisms associated with plant responses to fungal infection and mycotoxin contamination(1,2,3,4,5,6). Because many labs are using kernel assays to study plant-pathogen interactions, there is a need for a standardized method for quantifying different biological parameters, so results from different laboratories can be cross-interpreted. For a robust and reproducible means for quantitative analyses on seeds, we have developed in-lab kernel assays and subsequent methods to quantify fungal growth, biomass, and mycotoxin contamination. Four sterilized maize kernels are inoculated in glass vials with a fungal suspension (10(6)) and incubated for a predetermined period. Sample vials are then selected for enumeration of conidia by hemocytometer, ergosterol-based biomass analysis by high performance liquid chromatography (HPLC), aflatoxin quantification using an AflaTest fluorometer method, and fumonisin quantification by HPLC.
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