1
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Woo J, Jung S, Kim S, Li Y, Chung H, Roubtsova TV, Zhang H, Caseys C, Kliebenstein D, Kim KN, Bostock RM, Lee YH, Dickman MB, Choi D, Park E, Dinesh-Kumar SP. Attenuation of phytofungal pathogenicity of Ascomycota by autophagy modulators. Nat Commun 2024; 15:1621. [PMID: 38424448 PMCID: PMC10904834 DOI: 10.1038/s41467-024-45839-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Accepted: 02/02/2024] [Indexed: 03/02/2024] Open
Abstract
Autophagy in eukaryotes functions to maintain homeostasis by degradation and recycling of long-lived and unwanted cellular materials. Autophagy plays important roles in pathogenicity of various fungal pathogens, suggesting that autophagy is a novel target for development of antifungal compounds. Here, we describe bioluminescence resonance energy transfer (BRET)-based high-throughput screening (HTS) strategy to identify compounds that inhibit fungal ATG4 cysteine protease-mediated cleavage of ATG8 that is critical for autophagosome formation. We identified ebselen (EB) and its analogs ebselen oxide (EO) and 2-(4-methylphenyl)-1,2-benzisothiazol-3(2H)-one (PT) as inhibitors of fungal pathogens Botrytis cinerea and Magnaporthe oryzae ATG4-mediated ATG8 processing. The EB and its analogs inhibit spore germination, hyphal development, and appressorium formation in Ascomycota pathogens, B. cinerea, M. oryzae, Sclerotinia sclerotiorum and Monilinia fructicola. Treatment with EB and its analogs significantly reduced fungal pathogenicity. Our findings provide molecular insights to develop the next generation of antifungal compounds by targeting autophagy in important fungal pathogens.
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Affiliation(s)
- Jongchan Woo
- Department of Plant Biology and the Genome Center, College of Biological Sciences, University of California, Davis, CA, USA
- Department of Molecular Biology, College of Agriculture, Life Sciences and Natural Resources, University of Wyoming, Laramie, WY, USA
- Plant Immunity Research Center, College of Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea
| | - Seungmee Jung
- Department of Molecular Biology, College of Agriculture, Life Sciences and Natural Resources, University of Wyoming, Laramie, WY, USA
| | - Seongbeom Kim
- Department of Agricultural Biotechnology, College of Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea
| | - Yurong Li
- Department of Plant Pathology and Microbiology, College of Agriculture and Life Sciences, Texas A & M University, College Station, TX, USA
- Corteva Agriscience, Johnston, IA, USA
| | - Hyunjung Chung
- Department of Agricultural Biotechnology, College of Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea
| | - Tatiana V Roubtsova
- Department of Plant Pathology, College of Agriculture and Environmental Sciences, University of California, Davis, CA, USA
| | - Honghong Zhang
- Department of Plant Pathology and Microbiology, College of Agriculture and Life Sciences, Texas A & M University, College Station, TX, USA
- Fujian University Key Laboratory for Plant-Microbe Interaction, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Celine Caseys
- Department of Plant Sciences, College of Agriculture and Environmental Sciences, University of California, Davis, CA, USA
| | - Dan Kliebenstein
- Department of Plant Sciences, College of Agriculture and Environmental Sciences, University of California, Davis, CA, USA
| | - Kyung-Nam Kim
- Department of Bioindustry and Bioresource Engineering, College of Life Sciences, Sejong University, Seoul, Republic of Korea
| | - Richard M Bostock
- Department of Plant Pathology, College of Agriculture and Environmental Sciences, University of California, Davis, CA, USA
| | - Yong-Hwan Lee
- Department of Agricultural Biotechnology, College of Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea
| | - Martin B Dickman
- Department of Plant Pathology and Microbiology, College of Agriculture and Life Sciences, Texas A & M University, College Station, TX, USA
| | - Doil Choi
- Plant Immunity Research Center, College of Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea.
| | - Eunsook Park
- Department of Molecular Biology, College of Agriculture, Life Sciences and Natural Resources, University of Wyoming, Laramie, WY, USA.
| | - Savithramma P Dinesh-Kumar
- Department of Plant Biology and the Genome Center, College of Biological Sciences, University of California, Davis, CA, USA.
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2
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Gayral M, Arias Gaguancela O, Vasquez E, Herath V, Flores FJ, Dickman MB, Verchot J. Multiple ER-to-nucleus stress signaling pathways are activated during Plantago asiatica mosaic virus and Turnip mosaic virus infection in Arabidopsis thaliana. Plant J 2020; 103:1233-1245. [PMID: 32390256 DOI: 10.1111/tpj.14798] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 04/02/2020] [Accepted: 04/23/2020] [Indexed: 05/22/2023]
Abstract
Pathogens and other adverse environmental conditions can trigger endoplasmic reticulum (ER) stress. ER stress signaling increases the expression of cytoprotective ER-chaperones. The inositol-requiring enzyme (IRE1) is one ER stress sensor that is activated to splice the bZIP60 mRNA that produces a truncated transcription factor that activates gene expression in the nucleus. The IRE1/bZIP60 pathway is associated with restricting potyvirus and potexvirus infection. This study shows that the Plantago asiatica mosaic virus (PlAMV) triple gene block 3 (TGB3) and the Turnip mosaic virus (TuMV) 6K2 proteins activate alternative transcription pathways involving the bZIP17, bZIP28, BAG7, NAC089 and NAC103 factors in Arabidopsis thaliana. Using the corresponding knockout mutant lines, we show that bZIP17, bZIP60, BAG7 and NAC089 are factors in reducing PlAMV infection, whereas bZIP28 and bZIP60 are factors in reducing TuMV infection. We propose a model in which bZIP60 and bZIP17 synergistically induce genes restricting PlAMV infection, while bZIP60 and bZIP28 independently induce genes supporting PlAMV infection. Regarding TuMV-green fluorescent protein (GFP) infection, bZIP60 and bZIP28 serve to repress local and systemic infection. Finally, tauroursodeoxycholic acid treatments were used to demonstrate that the protein folding capacity significantly influences PlAMV accumulation.
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Affiliation(s)
- Mathieu Gayral
- Texas A&M Agrilife Research and Extension Center in Dallas, 17360 Coit Rd, Dallas, TX, 75252, USA
| | - Omar Arias Gaguancela
- Texas A&M Agrilife Research and Extension Center in Dallas, 17360 Coit Rd, Dallas, TX, 75252, USA
| | - Evelyn Vasquez
- Departamento de Ciencias de la Vida y la Agricultura, Universidad de las Fuerzas Armadas-ESPE, Av. General Rumiñahui s/n y Ambato, Sangolquí, 171103, Ecuador
| | - Venura Herath
- Texas A&M Agrilife Research and Extension Center in Dallas, 17360 Coit Rd, Dallas, TX, 75252, USA
- Department of Plant Pathology and Microbiology, Institute for Plant Genomics and Biotechnology, Texas A&M University, 498 Olsen Blvd, College Station, TX, 77843, USA
- Department of Agricultural Biology, Faculty of Agriculture, University of Peradeniya, Peradeniya, 20400, Sri Lanka
| | - Francisco J Flores
- Departamento de Ciencias de la Vida y la Agricultura, Universidad de las Fuerzas Armadas-ESPE, Av. General Rumiñahui s/n y Ambato, Sangolquí, 171103, Ecuador
- Centro de Investigación de Alimentos, CIAL, Facultad de Ciencias de la Ingeniería e Industrias, Universidad Tecnológica Equinoccial-UTE, Av. Mariscal Sucre y Mariana de Jesús, Quito, Pichincha, 170129, Ecuador
| | - Martin B Dickman
- Department of Plant Pathology and Microbiology, Institute for Plant Genomics and Biotechnology, Texas A&M University, 498 Olsen Blvd, College Station, TX, 77843, USA
| | - Jeanmarie Verchot
- Texas A&M Agrilife Research and Extension Center in Dallas, 17360 Coit Rd, Dallas, TX, 75252, USA
- Department of Plant Pathology and Microbiology, Institute for Plant Genomics and Biotechnology, Texas A&M University, 498 Olsen Blvd, College Station, TX, 77843, USA
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3
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Zhang H, Li Y, Dickman MB, Wang Z. Cytoprotective Co-chaperone BcBAG1 Is a Component for Fungal Development, Virulence, and Unfolded Protein Response (UPR) of Botrytis cinerea. Front Microbiol 2019; 10:685. [PMID: 31024482 PMCID: PMC6467101 DOI: 10.3389/fmicb.2019.00685] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Accepted: 03/19/2019] [Indexed: 11/25/2022] Open
Abstract
The Bcl-2 associated athanogene (BAG) family is an evolutionarily conserved group of co-chaperones that confers stress protection against a variety of cellular insults extending from yeasts, plants to humans. Little is known, however, regarding the biological role of BAG proteins in phytopathogenic fungi. Here, we identified the unique BAG gene (BcBAG1) from the necrotrophic fungal pathogen, Botrytis cinerea. BcBAG1 is the homolog of Arabidopsis thaliana AtBAG4, and ectopic expression of BcBAG1 in atbag4 knock-out mutants restores salt tolerance. BcBAG1 deletion mutants (ΔBcbag1) exhibited decreased conidiation, enhanced melanin accumulation and lost the ability to develop sclerotia. Also, BcBAG1 disruption blocked fungal conidial germination and successful penetration, leading to a reduced virulence in host plants. BcBAG1 contains BAG (BD) domain at C-terminus and ubiquitin-like (UBL) domain at N-terminus. Complementation assays indicated that BD can largely restored pathogenicity of ΔBcbag1. Abiotic stress assays showed ΔBcbag1 was more sensitive than the wild-type strain to NaCl, calcofluor white, SDS, tunicamycin, dithiothreitol (DTT), heat and cold stress, suggesting BcBAG1 plays a cytoprotective role during salt stress, cell wall stress, and ER stress. BcBAG1 negatively regulated the expression of BcBIP1, BcIRE1 and the splicing of BcHAC1 mRNA, which are core regulators of unfolded protein response (UPR) during ER stress. Moreover, BcBAG1 interacted with HSP70-type chaperones, BcBIP1 and BcSKS2. In summary, this work demonstrates that BcBAG1 is pleiotropic and not only essential for fungal development, hyphal melanization, and virulence, but also required for response to multiple abiotic stresses and UPR pathway of B. cinerea.
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Affiliation(s)
- Honghong Zhang
- Fujian University Key Laboratory for Plant-Microbe Interaction, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, China.,Institute for Plant Genomics and Biotechnology, College of Agriculture and Life Sciences, Texas A&M University, College Station, TX, United States.,Department of Plant Pathology and Microbiology, College of Agriculture and Life Sciences, Texas A&M University, College Station, TX, United States
| | - Yurong Li
- Institute for Plant Genomics and Biotechnology, College of Agriculture and Life Sciences, Texas A&M University, College Station, TX, United States.,Department of Plant Pathology and Microbiology, College of Agriculture and Life Sciences, Texas A&M University, College Station, TX, United States
| | - Martin B Dickman
- Institute for Plant Genomics and Biotechnology, College of Agriculture and Life Sciences, Texas A&M University, College Station, TX, United States.,Department of Plant Pathology and Microbiology, College of Agriculture and Life Sciences, Texas A&M University, College Station, TX, United States
| | - Zonghua Wang
- Fujian University Key Laboratory for Plant-Microbe Interaction, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, China.,Institute of Oceanography, Minjiang University, Fuzhou, China
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4
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Njaci I, Williams B, Castillo-González C, Dickman MB, Zhang X, Mundree S. Genome-Wide Investigation of the Role of MicroRNAs in Desiccation Tolerance in the Resurrection Grass Tripogon loliiformis. Plants (Basel) 2018; 7:E68. [PMID: 30200279 PMCID: PMC6161015 DOI: 10.3390/plants7030068] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 08/24/2018] [Accepted: 08/29/2018] [Indexed: 12/15/2022]
Abstract
Drought causes approximately two-thirds of crop and yield loss worldwide. To sustain future generations, there is a need to develop robust crops with enhanced water use efficiency. Resurrection plants are naturally resilient and tolerate up to 95% water loss with the ability to revive upon watering. Stress is genetically encoded and resilient species may garner tolerance by tightly regulating the expression of stress-related genes. MicroRNAs (miRNAs) post-transcriptionally regulate development and other stress response processes in eukaryotes. However, their role in resurrection plant desiccation tolerance is poorly understood. In this study, small RNA sequencing and miRNA expression profiling was conducted using Tripogon loliiformis plants subjected to extreme water deficit conditions. Differentially expressed miRNA profiles, target mRNAs, and their regulatory processes were elucidated. Gene ontology enrichment analysis revealed that development, stress response, and regulation of programmed cell death biological processes; Oxidoreductase and hydrolyase molecular activities; and SPL, MYB, and WRKY transcription factors were targeted by miRNAs during dehydration stress, indicating the indispensable regulatory role of miRNAs in desiccation tolerance. This study provides insights into the molecular mechanisms of desiccation tolerance in the resurrection plant T. loliiformis. This information will be useful in devising strategies for crop improvement on enhanced drought tolerance and water use efficiency.
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Affiliation(s)
- Isaac Njaci
- Centre for Tropical Crops and Biocommodities, Queensland University of Technology, Brisbane, QLD 4000, Australia.
| | - Brett Williams
- Centre for Tropical Crops and Biocommodities, Queensland University of Technology, Brisbane, QLD 4000, Australia.
| | - Claudia Castillo-González
- Department of Biochemistry and Biophysics, Institute for Plant Genomics and Biotechnology, Texas A&M University, College Station, TX 77843, USA.
| | - Martin B Dickman
- Department of Plant Pathology and Microbiology, Institute for Plant Genomics and Biotechnology, Texas A&M University, College Station, TX 77843, USA.
| | - Xiuren Zhang
- Department of Biochemistry and Biophysics, Institute for Plant Genomics and Biotechnology, Texas A&M University, College Station, TX 77843, USA.
| | - Sagadevan Mundree
- Centre for Tropical Crops and Biocommodities, Queensland University of Technology, Brisbane, QLD 4000, Australia.
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5
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Affiliation(s)
- Keying Yan
- Department of Plant Pathology, University of Nebraska, Lincoln, Nebraska 68583-0722
| | - Martin B. Dickman
- Department of Plant Pathology, University of Nebraska, Lincoln, Nebraska 68583-0722
| | - Jin-Rong Xu
- Department of Plant Pathology, Kansas State University, Manhattan, Kansas 66506-5502
| | - John F. Leslie
- Department of Plant Pathology, Kansas State University, Manhattan, Kansas 66506-5502
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6
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Carmona-Gutierrez D, Bauer MA, Zimmermann A, Aguilera A, Austriaco N, Ayscough K, Balzan R, Bar-Nun S, Barrientos A, Belenky P, Blondel M, Braun RJ, Breitenbach M, Burhans WC, Büttner S, Cavalieri D, Chang M, Cooper KF, Côrte-Real M, Costa V, Cullin C, Dawes I, Dengjel J, Dickman MB, Eisenberg T, Fahrenkrog B, Fasel N, Fröhlich KU, Gargouri A, Giannattasio S, Goffrini P, Gourlay CW, Grant CM, Greenwood MT, Guaragnella N, Heger T, Heinisch J, Herker E, Herrmann JM, Hofer S, Jiménez-Ruiz A, Jungwirth H, Kainz K, Kontoyiannis DP, Ludovico P, Manon S, Martegani E, Mazzoni C, Megeney LA, Meisinger C, Nielsen J, Nyström T, Osiewacz HD, Outeiro TF, Park HO, Pendl T, Petranovic D, Picot S, Polčic P, Powers T, Ramsdale M, Rinnerthaler M, Rockenfeller P, Ruckenstuhl C, Schaffrath R, Segovia M, Severin FF, Sharon A, Sigrist SJ, Sommer-Ruck C, Sousa MJ, Thevelein JM, Thevissen K, Titorenko V, Toledano MB, Tuite M, Vögtle FN, Westermann B, Winderickx J, Wissing S, Wölfl S, Zhang ZJ, Zhao RY, Zhou B, Galluzzi L, Kroemer G, Madeo F. Guidelines and recommendations on yeast cell death nomenclature. Microb Cell 2018; 5:4-31. [PMID: 29354647 PMCID: PMC5772036 DOI: 10.15698/mic2018.01.607] [Citation(s) in RCA: 121] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 12/29/2017] [Indexed: 12/18/2022]
Abstract
Elucidating the biology of yeast in its full complexity has major implications for science, medicine and industry. One of the most critical processes determining yeast life and physiology is cel-lular demise. However, the investigation of yeast cell death is a relatively young field, and a widely accepted set of concepts and terms is still missing. Here, we propose unified criteria for the defi-nition of accidental, regulated, and programmed forms of cell death in yeast based on a series of morphological and biochemical criteria. Specifically, we provide consensus guidelines on the differ-ential definition of terms including apoptosis, regulated necrosis, and autophagic cell death, as we refer to additional cell death rou-tines that are relevant for the biology of (at least some species of) yeast. As this area of investigation advances rapidly, changes and extensions to this set of recommendations will be implemented in the years to come. Nonetheless, we strongly encourage the au-thors, reviewers and editors of scientific articles to adopt these collective standards in order to establish an accurate framework for yeast cell death research and, ultimately, to accelerate the pro-gress of this vibrant field of research.
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Affiliation(s)
| | - Maria Anna Bauer
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
| | - Andreas Zimmermann
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
| | - Andrés Aguilera
- Centro Andaluz de Biología, Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla, Sevilla, Spain
| | | | - Kathryn Ayscough
- Department of Biomedical Science, University of Sheffield, Sheffield, United Kingdom
| | - Rena Balzan
- Department of Physiology and Biochemistry, University of Malta, Msida, Malta
| | - Shoshana Bar-Nun
- Department of Biochemistry and Molecular Biology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Antonio Barrientos
- Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, USA
- Department of Neurology, University of Miami Miller School of Medi-cine, Miami, USA
| | - Peter Belenky
- Department of Molecular Microbiology and Immunology, Brown University, Providence, USA
| | - Marc Blondel
- Institut National de la Santé et de la Recherche Médicale UMR1078, Université de Bretagne Occidentale, Etablissement Français du Sang Bretagne, CHRU Brest, Hôpital Morvan, Laboratoire de Génétique Moléculaire, Brest, France
| | - Ralf J. Braun
- Institute of Cell Biology, University of Bayreuth, Bayreuth, Germany
| | | | - William C. Burhans
- Department of Molecular and Cellular Biology, Roswell Park Cancer Institute, Buffalo, NY, USA
| | - Sabrina Büttner
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | | | - Michael Chang
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Katrina F. Cooper
- Dept. Molecular Biology, Graduate School of Biomedical Sciences, Rowan University, Stratford, USA
| | - Manuela Côrte-Real
- Center of Molecular and Environmental Biology, Department of Biology, University of Minho, Braga, Portugal
| | - Vítor Costa
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
- Departamento de Biologia Molecular, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
| | | | - Ian Dawes
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia
| | - Jörn Dengjel
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Martin B. Dickman
- Institute for Plant Genomics and Biotechnology, Texas A&M University, Texas, USA
| | - Tobias Eisenberg
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
- BioTechMed Graz, Graz, Austria
| | - Birthe Fahrenkrog
- Laboratory Biology of the Nucleus, Institute for Molecular Biology and Medicine, Université Libre de Bruxelles, Charleroi, Belgium
| | - Nicolas Fasel
- Department of Biochemistry, University of Lausanne, Lausanne, Switzerland
| | - Kai-Uwe Fröhlich
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
| | - Ali Gargouri
- Laboratoire de Biotechnologie Moléculaire des Eucaryotes, Center de Biotechnologie de Sfax, Sfax, Tunisia
| | - Sergio Giannattasio
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, National Research Council, Bari, Italy
| | - Paola Goffrini
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parma, Italy
| | - Campbell W. Gourlay
- Kent Fungal Group, School of Biosciences, University of Kent, Canterbury, United Kingdom
| | - Chris M. Grant
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom
| | - Michael T. Greenwood
- Department of Chemistry and Chemical Engineering, Royal Military College, Kingston, Ontario, Canada
| | - Nicoletta Guaragnella
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, National Research Council, Bari, Italy
| | | | - Jürgen Heinisch
- Department of Biology and Chemistry, University of Osnabrück, Osnabrück, Germany
| | - Eva Herker
- Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
| | | | - Sebastian Hofer
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
| | | | - Helmut Jungwirth
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
| | - Katharina Kainz
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
| | - Dimitrios P. Kontoyiannis
- Division of Internal Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Paula Ludovico
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Minho, Portugal
- ICVS/3B’s - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Stéphen Manon
- Institut de Biochimie et de Génétique Cellulaires, UMR5095, CNRS & Université de Bordeaux, Bordeaux, France
| | - Enzo Martegani
- Department of Biotechnolgy and Biosciences, University of Milano-Bicocca, Milano, Italy
| | - Cristina Mazzoni
- Instituto Pasteur-Fondazione Cenci Bolognetti - Department of Biology and Biotechnology "C. Darwin", La Sapienza University of Rome, Rome, Italy
| | - Lynn A. Megeney
- Sprott Center for Stem Cell Research, Ottawa Hospital Research Institute, The Ottawa Hospital, Ottawa, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Canada
- Department of Medicine, Division of Cardiology, University of Ottawa, Ottawa, Canada
| | - Chris Meisinger
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Jens Nielsen
- Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
- Novo Nordisk Foundation Center for Biosustainability, Chalmers University of Technology, Gothenburg, Sweden
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, DK2800 Lyngby, Denmark
| | - Thomas Nyström
- Institute for Biomedicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Heinz D. Osiewacz
- Institute for Molecular Biosciences, Goethe University, Frankfurt am Main, Germany
| | - Tiago F. Outeiro
- Department of Experimental Neurodegeneration, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
- Max Planck Institute for Experimental Medicine, Göttingen, Germany
- Institute of Neuroscience, The Medical School, Newcastle University, Framlington Place, Newcastle Upon Tyne, NE2 4HH, United Kingdom
- CEDOC, Chronic Diseases Research Centre, NOVA Medical School, Faculdade de Ciências Médicas, Universidade NOVA de Lisboa, Lisboa, Portugal
| | - Hay-Oak Park
- Department of Molecular Genetics, The Ohio State University, Columbus, OH, USA
| | - Tobias Pendl
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
| | - Dina Petranovic
- Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
- Novo Nordisk Foundation Center for Biosustainability, Chalmers University of Technology, Gothenburg, Sweden
| | - Stephane Picot
- Malaria Research Unit, SMITh, ICBMS, UMR 5246 CNRS-INSA-CPE-University Lyon, Lyon, France
- Institut of Parasitology and Medical Mycology, Hospices Civils de Lyon, Lyon, France
| | - Peter Polčic
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Bratislava, Slovak Republic
| | - Ted Powers
- Department of Molecular and Cellular Biology, College of Biological Sciences, UC Davis, Davis, California, USA
| | - Mark Ramsdale
- Biosciences, University of Exeter, Exeter, United Kingdom
| | - Mark Rinnerthaler
- Department of Cell Biology and Physiology, Division of Genetics, University of Salzburg, Salzburg, Austria
| | - Patrick Rockenfeller
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
- Kent Fungal Group, School of Biosciences, University of Kent, Canterbury, United Kingdom
| | | | - Raffael Schaffrath
- Institute of Biology, Division of Microbiology, University of Kassel, Kassel, Germany
| | - Maria Segovia
- Department of Ecology, Faculty of Sciences, University of Malaga, Malaga, Spain
| | - Fedor F. Severin
- A.N. Belozersky Institute of physico-chemical biology, Moscow State University, Moscow, Russia
| | - Amir Sharon
- School of Plant Sciences and Food Security, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Stephan J. Sigrist
- Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany
| | - Cornelia Sommer-Ruck
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
| | - Maria João Sousa
- Center of Molecular and Environmental Biology, Department of Biology, University of Minho, Braga, Portugal
| | - Johan M. Thevelein
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU Leuven, Leuven, Belgium
- Center for Microbiology, VIB, Leuven-Heverlee, Belgium
| | - Karin Thevissen
- Centre of Microbial and Plant Genetics, KU Leuven, Leuven, Belgium
| | | | - Michel B. Toledano
- Institute for Integrative Biology of the Cell (I2BC), SBIGEM, CEA-Saclay, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Mick Tuite
- Kent Fungal Group, School of Biosciences, University of Kent, Canterbury, United Kingdom
| | - F.-Nora Vögtle
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | | | - Joris Winderickx
- Department of Biology, Functional Biology, KU Leuven, Leuven-Heverlee, Belgium
| | | | - Stefan Wölfl
- Institute of Pharmacy and Molecu-lar Biotechnology, Heidelberg University, Heidelberg, Germany
| | - Zhaojie J. Zhang
- Department of Zoology and Physiology, University of Wyoming, Laramie, USA
| | - Richard Y. Zhao
- Department of Pathology, University of Maryland School of Medicine, Baltimore, USA
| | - Bing Zhou
- School of Life Sciences, Tsinghua University, Beijing, China
| | - Lorenzo Galluzzi
- Department of Radiation Oncology, Weill Cornell Medical College, New York, NY, USA
- Sandra and Edward Meyer Cancer Center, New York, NY, USA
- Université Paris Descartes/Paris V, Paris, France
| | - Guido Kroemer
- Université Paris Descartes/Paris V, Paris, France
- Equipe 11 Labellisée Ligue Contre le Cancer, Centre de Recherche des Cordeliers, Paris, France
- Cell Biology and Metabolomics Platforms, Gustave Roussy Comprehensive Cancer Center, Villejuif, France
- INSERM, U1138, Paris, France
- Université Pierre et Marie Curie/Paris VI, Paris, France
- Pôle de Biologie, Hôpital Européen Georges Pompidou, Paris, France
- Institute, Department of Women’s and Children’s Health, Karolinska University Hospital, Stockholm, Sweden
| | - Frank Madeo
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
- BioTechMed Graz, Graz, Austria
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7
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Abstract
The Bcl-2-associated athanogene (BAG) family is a multifunctional group of
proteins involved in numerous cellular functions ranging from apoptosis to
tumorigenesis. These proteins are evolutionarily conserved and encode a
characteristic region known as the BAG domain. BAGs function as adapter proteins
forming complexes with signaling molecules and molecular chaperones. In humans,
a role for BAG proteins has been suggested in tumor growth, HIV infection, and
neurodegenerative diseases; as a result, the BAGs are attractive targets for
therapeutic interventions, and their expression in cells may serve as a
predictive tool for disease development. The Arabidopsis genome
contains seven homologs of BAG family proteins (Figure 1), including four with a
domain organization similar to animal BAGs (BAG1-4). The remaining three members
(BAG5-7) contain a predicted calmodulin-binding motif near the BAG domain, a
feature unique to plant BAG proteins that possibly reflects divergent mechanisms
associated with plant-specific functions. As reported for animal BAGs, plant
BAGs also regulate several stress and developmental processes (Figure 2). The
recent article by Li et al. focuses on the role of BAG6 in
plant innate immunity. This study shows that BAG6 plays a key role in basal
plant defense against fungal pathogens. Importantly, this work further shows
that BAG6 is proteolytically activated to induce autophagic cell death and
resistance in plants. This finding underscores the importance of proteases in
the execution of plant cell death, yet little is known about proteases and their
substrates in plants.
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Affiliation(s)
- Mehdi Kabbage
- University of Wisconsin-Madison, Department of Plant Pathology, Madison, WI 53706
| | - Ryan Kessens
- University of Wisconsin-Madison, Department of Plant Pathology, Madison, WI 53706
| | - Martin B Dickman
- Texas A&M University, Department of Plant Pathology and Microbiology, Institute for Plant Genomics and Biotechnology, College Station, TX 77843
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8
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Li Y, Kabbage M, Liu W, Dickman MB. Aspartyl Protease-Mediated Cleavage of BAG6 Is Necessary for Autophagy and Fungal Resistance in Plants. Plant Cell 2016; 28:233-47. [PMID: 26739014 PMCID: PMC4746679 DOI: 10.1105/tpc.15.00626] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Revised: 11/24/2015] [Accepted: 12/31/2015] [Indexed: 05/04/2023]
Abstract
The Bcl-2-associated athanogene (BAG) family is an evolutionarily conserved group of cochaperones that modulate numerous cellular processes. Previously we found that Arabidopsis thaliana BAG6 is required for basal immunity against the fungal phytopathogen Botrytis cinerea. However, the mechanisms by which BAG6 controls immunity are obscure. Here, we address this important question by determining the molecular mechanisms responsible for BAG6-mediated basal resistance. We show that Arabidopsis BAG6 is cleaved in vivo in a caspase-1-like-dependent manner and via a combination of pull-downs, mass spectrometry, yeast two-hybrid assays, and chemical genomics, we demonstrate that BAG6 interacts with a C2 GRAM domain protein (BAGP1) and an aspartyl protease (APCB1), both of which are required for BAG6 processing. Furthermore, fluorescence and transmission electron microscopy established that BAG6 cleavage triggers autophagy in the host that coincides with disease resistance. Targeted inactivation of BAGP1 or APCB1 results in the blocking of BAG6 processing and loss of resistance. Mutation of the cleavage site blocks cleavage and inhibits autophagy in plants; disease resistance is also compromised. Taken together, these results identify a mechanism that couples an aspartyl protease with a molecular cochaperone to trigger autophagy and plant defense, providing a key link between fungal recognition and the induction of cell death and resistance.
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Affiliation(s)
- Yurong Li
- Institute for Plant Genomics and Biotechnology, Texas A&M University, College Station, Texas 77843 Department of Plant Pathology and Microbiology, Texas A&M University, College Station, Texas 77843
| | - Mehdi Kabbage
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - Wende Liu
- Institute for Plant Genomics and Biotechnology, Texas A&M University, College Station, Texas 77843
| | - Martin B Dickman
- Institute for Plant Genomics and Biotechnology, Texas A&M University, College Station, Texas 77843 Department of Plant Pathology and Microbiology, Texas A&M University, College Station, Texas 77843
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9
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Williams B, Njaci I, Moghaddam L, Long H, Dickman MB, Zhang X, Mundree S. Trehalose Accumulation Triggers Autophagy during Plant Desiccation. PLoS Genet 2015; 11:e1005705. [PMID: 26633550 PMCID: PMC4669190 DOI: 10.1371/journal.pgen.1005705] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Accepted: 11/06/2015] [Indexed: 12/19/2022] Open
Abstract
Global climate change, increasingly erratic weather and a burgeoning global population are significant threats to the sustainability of future crop production. There is an urgent need for the development of robust measures that enable crops to withstand the uncertainty of climate change whilst still producing maximum yields. Resurrection plants possess the unique ability to withstand desiccation for prolonged periods, can be restored upon watering and represent great potential for the development of stress tolerant crops. Here, we describe the remarkable stress characteristics of Tripogon loliiformis, an uncharacterised resurrection grass and close relative of the economically important cereals, rice, sorghum, and maize. We show that T. loliiformis survives extreme environmental stress by implementing autophagy to prevent Programmed Cell Death. Notably, we identified a novel role for trehalose in the regulation of autophagy in T.loliiformis. Transcriptome, Gas Chromatography Mass Spectrometry, immunoblotting and confocal microscopy analyses directly linked the accumulation of trehalose with the onset of autophagy in dehydrating and desiccated T. loliiformis shoots. These results were supported in vitro with the observation of autophagosomes in trehalose treated T. loliiformis leaves; autophagosomes were not detected in untreated samples. Presumably, once induced, autophagy promotes desiccation tolerance in T.loliiformis, by removal of cellular toxins to suppress programmed cell death and the recycling of nutrients to delay the onset of senescence. These findings illustrate how resurrection plants manipulate sugar metabolism to promote desiccation tolerance and may provide candidate genes that are potentially useful for the development of stress tolerant crops.
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Affiliation(s)
- Brett Williams
- Centre for Tropical Crops and Biocommodities, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Isaac Njaci
- Centre for Tropical Crops and Biocommodities, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Lalehvash Moghaddam
- Centre for Tropical Crops and Biocommodities, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Hao Long
- Centre for Tropical Crops and Biocommodities, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Martin B Dickman
- Department of Plant Pathology and Microbiology, Institute for Plant Genomics and Biotechnology, Texas A&M University, College Station, Texas, United States of America
| | - Xiuren Zhang
- Department of Biochemistry and Biophysics, Institute for Plant Genomics and Biotechnology, Texas A&M University, College Station, Texas, United States of America
| | - Sagadevan Mundree
- Centre for Tropical Crops and Biocommodities, Queensland University of Technology, Brisbane, Queensland, Australia
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10
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Kabbage M, Yarden O, Dickman MB. Pathogenic attributes of Sclerotinia sclerotiorum: switching from a biotrophic to necrotrophic lifestyle. Plant Sci 2015; 233:53-60. [PMID: 25711813 DOI: 10.1016/j.plantsci.2014.12.018] [Citation(s) in RCA: 137] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Revised: 12/20/2014] [Accepted: 12/22/2014] [Indexed: 05/02/2023]
Abstract
Plants and fungi have had many years of friendly and not-so friendly competition for resources and quality of life. As a result, diverse pathosystems evolved numerous strategies, coupled with the emergence of multifaceted pathogenic and saprophytic lifestyles. We discuss fungal lifestyle classifications and how the views associated with certain fungal pathogens, particularly necrotophs, are changing as we learn more about the complexities of their interactions with a given host plant. We discuss the physiological events leading to the transition from biotrophy to necrotrophy in hemi-biotrophs, and conclude that both the control of plant immune responses and the need for a more efficient mode of nutrient acquisition are possible triggers for the transition to necrotrophy. Based on recent findings, we focus on the polyphagous plant pathogen Sclerotinia sclerotiorum. Rather than overwhelming plant foes, S. sclerotiorum has evolved clever means to compromise host recognition and establish disease, resulting in a broad and immensely successful pathogenic lifestyle. The tactics used by this fungus to achieve pathogenic success are being clarified. We propose that the hemi-biotrophic lifestyle may be more temporally and spatially complex than currently depicted, and that combining lifestyle attributes with damage response curves that consider the contribution of both the fungus and the host to pathogenesis, may provide a more holistic manner to view plant pathogens.
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Affiliation(s)
- Mehdi Kabbage
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, USA
| | - Oded Yarden
- Department of Plant Pathology and Microbiology, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 7600, Israel
| | - Martin B Dickman
- Institute for Plant Genomics and Biotechnology, Texas A&M University, College Station, TX, USA; Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843, USA.
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11
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Okubara PA, Dickman MB, Blechl AE. Molecular and genetic aspects of controlling the soilborne necrotrophic pathogens Rhizoctonia and Pythium. Plant Sci 2014; 228:61-70. [PMID: 25438786 DOI: 10.1016/j.plantsci.2014.02.001] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 01/22/2014] [Accepted: 02/03/2014] [Indexed: 05/20/2023]
Abstract
The soilborne necrotrophic pathogens Rhizoctonia and Pythium infect a wide range of crops in the US and worldwide. These pathogens pose challenges to growers because the diseases they cause are not adequately controlled by fungicides, rotation or, for many hosts, natural genetic resistance. Although a combination of management practices are likely to be required for control of Rhizoctonia and Pythium, genetic resistance remains a key missing component. This review discusses the recent deployment of introduced genes and genome-based information for control of Rhizoctonia, with emphasis on three pathosystems: Rhizoctonia solani AG8 and wheat, R. solani AG1-IA and rice, and R. solani AG3 or AG4 and potato. Molecular mechanisms underlying disease suppression will be addressed, if appropriate. Although less is known about genes and factors suppressive to Pythium, pathogen genomics and biological control studies are providing useful leads to effectors and antifungal factors. Prospects for resistance to Rhizoctonia and Pythium spp. will continue to improve with growing knowledge of pathogenicity strategies, host defense gene action relative to the pathogen infection process, and the role of environmental factors on pathogen-host interactions.
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Affiliation(s)
- Patricia A Okubara
- USDA-ARS, Root Disease and Biological Control Research Unit, Pullman, WA, 99164-6430, USA.
| | - Martin B Dickman
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843-2123, USA
| | - Ann E Blechl
- USDA-ARS, Crop Improvement and Utilization Research Unit, 800 Buchanan Street, Albany, CA, 94710-1105, USA
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12
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Liang X, Dickman MB, Becker DF. Proline biosynthesis is required for endoplasmic reticulum stress tolerance in Saccharomyces cerevisiae. J Biol Chem 2014; 289:27794-806. [PMID: 25112878 PMCID: PMC4183814 DOI: 10.1074/jbc.m114.562827] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 07/30/2014] [Indexed: 12/13/2022] Open
Abstract
The amino acid proline is uniquely involved in cellular processes that underlie stress response in a variety of organisms. Proline is known to minimize protein aggregation, but a detailed study of how proline impacts cell survival during accumulation of misfolded proteins in the endoplasmic reticulum (ER) has not been performed. To address this we examined in Saccharomyces cerevisiae the effect of knocking out the PRO1, PRO2, and PRO3 genes responsible for proline biosynthesis. The null mutants pro1, pro2, and pro3 were shown to have increased sensitivity to ER stress relative to wild-type cells, which could be restored by proline or the corresponding genetic complementation. Of these mutants, pro3 was the most sensitive to tunicamycin and was rescued by anaerobic growth conditions or reduced thiol reagents. The pro3 mutant cells have higher intracellular reactive oxygen species, total glutathione, and a NADP(+)/NADPH ratio than wild-type cells under limiting proline conditions. Depletion of proline biosynthesis also inhibits the unfolded protein response (UPR) indicating proline protection involves the UPR. To more broadly test the role of proline in ER stress, increased proline biosynthesis was shown to partially rescue the ER stress sensitivity of a hog1 null mutant in which the high osmolality pathway is disrupted.
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Affiliation(s)
- Xinwen Liang
- From the Department of Biochemistry and Redox Biology Center, University of Nebraska, Lincoln, Nebraska 68588 and
| | - Martin B Dickman
- the Institute for Plant Genomics and Biotechnology, Department of Plant Pathology and Microbiology, Texas A&M University, College Station, Texas 77843
| | - Donald F Becker
- From the Department of Biochemistry and Redox Biology Center, University of Nebraska, Lincoln, Nebraska 68588 and
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13
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Williams B, Verchot J, Dickman MB. When supply does not meet demand-ER stress and plant programmed cell death. Front Plant Sci 2014; 5:211. [PMID: 24926295 DOI: 10.3389/fpls.2014.00211/abstract] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Accepted: 04/29/2014] [Indexed: 05/24/2023]
Abstract
The endoplasmic reticulum (ER) is the central organelle in the eukaryotic secretory pathway. The ER functions in protein synthesis and maturation and is crucial for proper maintenance of cellular homeostasis and adaptation to adverse environments. Acting as a cellular sentinel, the ER is exquisitely sensitive to changing environments principally via the ER quality control machinery. When perturbed, ER-stress triggers a tightly regulated and highly conserved, signal transduction pathway known as the unfolded protein response (UPR) that prevents the dangerous accumulation of unfolded/misfolded proteins. In situations where excessive UPR activity surpasses threshold levels, cells deteriorate and eventually trigger programmed cell death (PCD) as a way for the organism to cope with dysfunctional or toxic signals. The programmed cell death that results from excessive ER stress in mammalian systems contributes to several important diseases including hypoxia, neurodegeneration, and diabetes. Importantly, hallmark features and markers of cell death that are associated with ER stress in mammals are also found in plants. In particular, there is a common, conserved set of chaperones that modulate ER cell death signaling. Here we review the elements of plant cell death responses to ER stress and note that an increasing number of plant-pathogen interactions are being identified in which the host ER is targeted by plant pathogens to establish compatibility.
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Affiliation(s)
- Brett Williams
- Centre for Tropical Crops and Biocommodities, Queensland University of Technology Brisbane, QLD, Australia
| | - Jeanmarie Verchot
- Department of Entomology and Plant Pathology, Oklahoma State University Stillwater, OK, USA
| | - Martin B Dickman
- Department of Plant Pathology and Microbiology, Institute for Plant Genomics and Biotechnology, Texas A&M University College Station, TX, USA
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14
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Williams B, Verchot J, Dickman MB. When supply does not meet demand-ER stress and plant programmed cell death. Front Plant Sci 2014; 5:211. [PMID: 24926295 PMCID: PMC4045240 DOI: 10.3389/fpls.2014.00211] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Accepted: 04/29/2014] [Indexed: 05/10/2023]
Abstract
The endoplasmic reticulum (ER) is the central organelle in the eukaryotic secretory pathway. The ER functions in protein synthesis and maturation and is crucial for proper maintenance of cellular homeostasis and adaptation to adverse environments. Acting as a cellular sentinel, the ER is exquisitely sensitive to changing environments principally via the ER quality control machinery. When perturbed, ER-stress triggers a tightly regulated and highly conserved, signal transduction pathway known as the unfolded protein response (UPR) that prevents the dangerous accumulation of unfolded/misfolded proteins. In situations where excessive UPR activity surpasses threshold levels, cells deteriorate and eventually trigger programmed cell death (PCD) as a way for the organism to cope with dysfunctional or toxic signals. The programmed cell death that results from excessive ER stress in mammalian systems contributes to several important diseases including hypoxia, neurodegeneration, and diabetes. Importantly, hallmark features and markers of cell death that are associated with ER stress in mammals are also found in plants. In particular, there is a common, conserved set of chaperones that modulate ER cell death signaling. Here we review the elements of plant cell death responses to ER stress and note that an increasing number of plant-pathogen interactions are being identified in which the host ER is targeted by plant pathogens to establish compatibility.
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Affiliation(s)
- Brett Williams
- Centre for Tropical Crops and Biocommodities, Queensland University of TechnologyBrisbane, QLD, Australia
| | - Jeanmarie Verchot
- Department of Entomology and Plant Pathology, Oklahoma State UniversityStillwater, OK, USA
| | - Martin B. Dickman
- Department of Plant Pathology and Microbiology, Institute for Plant Genomics and Biotechnology, Texas A&M UniversityCollege Station, TX, USA
- *Correspondence: Martin B. Dickman, Department of Plant Pathology and Microbiology, Institute for Plant Genomics and Biotechnology, Texas A&M University, College Station, TX 77843, USA e-mail:
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15
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Affiliation(s)
- Martin B Dickman
- Norman Borlaug Center, Texas A&M University, College Station, Texas, United States of America ; Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M Health Science Center, College Station, Texas, United States of America
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16
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Affiliation(s)
- Michael F Criscitiello
- Comparative Immunogenetics Laboratory, Texas A&M University, College Station, Texas, United States of America.
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17
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Kabbage M, Williams B, Dickman MB. Cell death control: the interplay of apoptosis and autophagy in the pathogenicity of Sclerotinia sclerotiorum. PLoS Pathog 2013; 9:e1003287. [PMID: 23592997 PMCID: PMC3623803 DOI: 10.1371/journal.ppat.1003287] [Citation(s) in RCA: 164] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Accepted: 02/19/2013] [Indexed: 01/07/2023] Open
Abstract
Programmed cell death is characterized by a cascade of tightly controlled events that culminate in the orchestrated death of the cell. In multicellular organisms autophagy and apoptosis are recognized as two principal means by which these genetically determined cell deaths occur. During plant-microbe interactions cell death programs can mediate both resistant and susceptible events. Via oxalic acid (OA), the necrotrophic phytopathogen Sclerotinia sclerotiorum hijacks host pathways and induces cell death in host plant tissue resulting in hallmark apoptotic features in a time and dose dependent manner. OA-deficient mutants are non-pathogenic and trigger a restricted cell death phenotype in the host that unexpectedly exhibits markers associated with the plant hypersensitive response including callose deposition and a pronounced oxidative burst, suggesting the plant can recognize and in this case respond, defensively. The details of this plant directed restrictive cell death associated with OA deficient mutants is the focus of this work. Using a combination of electron and fluorescence microscopy, chemical effectors and reverse genetics, we show that this restricted cell death is autophagic. Inhibition of autophagy rescued the non-pathogenic mutant phenotype. These findings indicate that autophagy is a defense response in this necrotrophic fungus/plant interaction and suggest a novel function associated with OA; namely, the suppression of autophagy. These data suggest that not all cell deaths are equivalent, and though programmed cell death occurs in both situations, the outcome is predicated on who is in control of the cell death machinery. Based on our data, we suggest that it is not cell death per se that dictates the outcome of certain plant-microbe interactions, but the manner by which cell death occurs that is crucial. During plant-microbe interactions, regulated cell death known as programmed cell death (PCD) can mediate both resistant and susceptible interactions. Sclerotinia sclerotiorum induces an apoptotic spreading cell death during infection, via the secreted virulence determinant oxalic acid. Oxalic acid deficient fungal mutants are non-pathogenic, and trigger a restricted cell death phenotype in the host that unexpectedly exhibits markers associated with the plant hypersensitive response. Using electron and fluorescence microscopy, chemical effectors and reverse genetics, we show that this restricted cell death is autophagic. Inhibition of autophagy rescued the non-pathogenic mutant phenotype. These findings indicate that autophagy is a defense response in this interaction and suggest a novel function associated with oxalic acid: the suppression of autophagy. Thus, the control of cell death, dictated by the plant (autophagy) or the fungus (apoptosis), can lead to opposing outcomes. We propose that the type of cell death is decisive to the outcome of certain plant-microbe interactions.
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Affiliation(s)
- Mehdi Kabbage
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Brett Williams
- Centre for Tropical Crops and Biocommodities, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Martin B. Dickman
- Institute for Plant Genomics and Biotechnology, Texas A&M University, College Station, Texas, United States of America
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, Texas, United States of America
- Center for Cell Death and Differentiation, Texas A&M University, College Station, Texas, United States of America
- * E-mail:
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18
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Ye CM, Chen S, Payton M, Dickman MB, Verchot J. TGBp3 triggers the unfolded protein response and SKP1-dependent programmed cell death. Mol Plant Pathol 2013; 14:241-55. [PMID: 23458484 PMCID: PMC6638746 DOI: 10.1111/mpp.12000] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The Potato virus X (PVX) triple gene block protein 3 (TGBp3), an 8-kDa membrane binding protein, aids virus movement and induces the unfolded protein response (UPR) during PVX infection. TGBp3 was expressed from the Tobacco mosaic virus (TMV) genome (TMV-p3), and we noted the up-regulation of SKP1 and several endoplasmic reticulum (ER)-resident chaperones, including the ER luminal binding protein (BiP), protein disulphide isomerase (PDI), calreticulin (CRT) and calmodulin (CAM). Local lesions were seen on leaves inoculated with TMV-p3, but not TMV or PVX. Such lesions were the result of TGBp3-elicited programmed cell death (PCD), as shown by an increase in reactive oxygen species, DNA fragmentation and induction of SKP1 expression. UPR-related gene expression occurred within 8 h of TMV-p3 inoculation and declined before the onset of PCD. TGBp3-mediated cell death was suppressed in plants that overexpressed BiP, indicating that UPR induction by TGBp3 is a pro-survival mechanism. Anti-apoptotic genes Bcl-xl, CED-9 and Op-IAP were expressed in transgenic plants and suppressed N gene-mediated resistance to TMV, but failed to alleviate TGBp3-induced PCD. However, TGBp3-mediated cell death was reduced in SKP1-silenced Nicotiana benthamiana plants. The combined data suggest that TGBp3 triggers the UPR and elicits PCD in plants.
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Affiliation(s)
- Chang-Ming Ye
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA
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19
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Abstract
The Potato virus X (PVX) triple gene block protein 3 (TGBp3), an 8-kDa membrane binding protein, aids virus movement and induces the unfolded protein response (UPR) during PVX infection. TGBp3 was expressed from the Tobacco mosaic virus (TMV) genome (TMV-p3), and we noted the up-regulation of SKP1 and several endoplasmic reticulum (ER)-resident chaperones, including the ER luminal binding protein (BiP), protein disulphide isomerase (PDI), calreticulin (CRT) and calmodulin (CAM). Local lesions were seen on leaves inoculated with TMV-p3, but not TMV or PVX. Such lesions were the result of TGBp3-elicited programmed cell death (PCD), as shown by an increase in reactive oxygen species, DNA fragmentation and induction of SKP1 expression. UPR-related gene expression occurred within 8 h of TMV-p3 inoculation and declined before the onset of PCD. TGBp3-mediated cell death was suppressed in plants that overexpressed BiP, indicating that UPR induction by TGBp3 is a pro-survival mechanism. Anti-apoptotic genes Bcl-xl, CED-9 and Op-IAP were expressed in transgenic plants and suppressed N gene-mediated resistance to TMV, but failed to alleviate TGBp3-induced PCD. However, TGBp3-mediated cell death was reduced in SKP1-silenced Nicotiana benthamiana plants. The combined data suggest that TGBp3 triggers the UPR and elicits PCD in plants.
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Affiliation(s)
- Chang-Ming Ye
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA
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20
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Zhu W, Wei W, Fu Y, Cheng J, Xie J, Li G, Yi X, Kang Z, Dickman MB, Jiang D. A secretory protein of necrotrophic fungus Sclerotinia sclerotiorum that suppresses host resistance. PLoS One 2013; 8:e53901. [PMID: 23342034 PMCID: PMC3544710 DOI: 10.1371/journal.pone.0053901] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Accepted: 12/04/2012] [Indexed: 01/08/2023] Open
Abstract
SSITL (SS1G_14133) of Sclerotinia sclerotiorum encodes a protein with 302 amino acid residues including a signal peptide, its secretion property was confirmed with immunolocalization and immunofluorescence techniques. SSITL was classified in the integrin alpha N-terminal domain superfamily, and its 3D structure is similar to those of human integrin α4-subunit and a fungal integrin-like protein. When S. sclerotiorum was inoculated to its host, high expression of SSITL was detected during the initial stages of infection (1.5–3.0 hpi). Targeted silencing of SSITL resulted in a significant reduction in virulence; on the other hand, inoculation of SSITL silenced transformant A10 initiated strong and rapid defense response in Arabidopsis, the highest expressions of defense genes PDF1.2 and PR-1 appeared at 3 hpi which was 9 hr earlier than that time when plants were inoculated with the wild-type strain of S. sclerotiorum. Systemic resistance induced by A10 was detected by analysis of the expression of PDF1.2 and PR-1, and confirmed following inoculation with Botrytis cinerea. A10 induced much larger lesions on Arabidopsis mutant ein2 and jar1, and slightly larger lesions on mutant pad4 and NahG in comparison with the wild-type plants. Furthermore, both transient and constitutive expression of SSITL in Arabidopsis suppressed the expression of PDF1.2 and led to be more susceptible to A10 and the wild-type strain of S. sclerotiorum and B. cinerea. Our results suggested that SSITL is an effector possibly and plays significant role in the suppression of jasmonic/ethylene (JA/ET) signal pathway mediated resistance at the early stage of infection.
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Affiliation(s)
- Wenjun Zhu
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei Province, People’s Republic of China
- The Provincial Key Lab of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei Province, People’s Republic of China
| | - Wei Wei
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei Province, People’s Republic of China
- The Provincial Key Lab of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei Province, People’s Republic of China
| | - Yanping Fu
- The Provincial Key Lab of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei Province, People’s Republic of China
| | - Jiasen Cheng
- The Provincial Key Lab of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei Province, People’s Republic of China
| | - Jiatao Xie
- The Provincial Key Lab of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei Province, People’s Republic of China
| | - Guoqing Li
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei Province, People’s Republic of China
- The Provincial Key Lab of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei Province, People’s Republic of China
| | - Xianhong Yi
- The Provincial Key Lab of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei Province, People’s Republic of China
| | - Zhensheng Kang
- State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling, Shaanxi, People’s Republic of China
| | - Martin B. Dickman
- Institute for Plant Genomics and Biotechnology, Department of Plant Pathology and Microbiology, Texas A&M University, College Station, Texas, United States of America
| | - Daohong Jiang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei Province, People’s Republic of China
- The Provincial Key Lab of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei Province, People’s Republic of China
- * E-mail:
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Abstract
Programmed cell death (PCD) is essential for proper growth, development, and cellular homeostasis in all eukaryotes. The regulation of PCD is of central importance in plant-microbe interactions; notably, PCD and features associated with PCD are observed in many host resistance responses. Conversely, pathogen induction of inappropriate cell death in the host results in a susceptible phenotype and disease. Thus, the party in control of PCD has a distinct advantage in these battles. PCD processes appear to be of ancient origin, as indicated by the fact that many features of cell death strategy are conserved between animals and plants; however, some of the details of death execution differ. Mammalian core PCD genes, such as caspases, are not present in plant genomes. Similarly, pro- and antiapoptotic mammalian regulatory elements are absent in plants, but, remarkably, when expressed in plants, successfully impact plant PCD. Thus, subtle structural similarities independent of sequence homology appear to sustain operational equivalence. The vacuole is emerging as a key organelle in the modulation of plant PCD. Under different signals for cell death, the vacuole either fuses with the plasmalemma membrane or disintegrates. Moreover, the vacuole appears to play a key role in autophagy; evidence suggests a prosurvival function for autophagy, but other studies propose a prodeath phenotype. Here, we describe and discuss what we know and what we do not know about various PCD pathways and how the host integrates signals to activate salicylic acid and reactive oxygen pathways that orchestrate cell death. We suggest that it is not cell death as such but rather the processes leading to cell death that contribute to the outcome of a given plant-pathogen interaction.
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Affiliation(s)
- Martin B Dickman
- Institute for Plant Genomics and Biotechnology, Center for Cell Death and Differentiation, Department of Plant Pathology and Microbiology, Texas A&M University, College Station, Texas 77843, USA.
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Ye CM, Kelly V, Payton M, Dickman MB, Verchot J. SGT1 is induced by the potato virus X TGBp3 and enhances virus accumulation in Nicotiana benthamiana. Mol Plant 2012; 5:1151-3. [PMID: 22461666 DOI: 10.1093/mp/sss026] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
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O'Connell RJ, Thon MR, Hacquard S, Amyotte SG, Kleemann J, Torres MF, Damm U, Buiate EA, Epstein L, Alkan N, Altmüller J, Alvarado-Balderrama L, Bauser CA, Becker C, Birren BW, Chen Z, Choi J, Crouch JA, Duvick JP, Farman MA, Gan P, Heiman D, Henrissat B, Howard RJ, Kabbage M, Koch C, Kracher B, Kubo Y, Law AD, Lebrun MH, Lee YH, Miyara I, Moore N, Neumann U, Nordström K, Panaccione DG, Panstruga R, Place M, Proctor RH, Prusky D, Rech G, Reinhardt R, Rollins JA, Rounsley S, Schardl CL, Schwartz DC, Shenoy N, Shirasu K, Sikhakolli UR, Stüber K, Sukno SA, Sweigard JA, Takano Y, Takahara H, Trail F, van der Does HC, Voll LM, Will I, Young S, Zeng Q, Zhang J, Zhou S, Dickman MB, Schulze-Lefert P, Ver Loren van Themaat E, Ma LJ, Vaillancourt LJ. Lifestyle transitions in plant pathogenic Colletotrichum fungi deciphered by genome and transcriptome analyses. Nat Genet 2012; 44:1060-5. [PMID: 22885923 DOI: 10.1038/ng.2372] [Citation(s) in RCA: 561] [Impact Index Per Article: 46.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Accepted: 07/05/2012] [Indexed: 11/09/2022]
Abstract
Colletotrichum species are fungal pathogens that devastate crop plants worldwide. Host infection involves the differentiation of specialized cell types that are associated with penetration, growth inside living host cells (biotrophy) and tissue destruction (necrotrophy). We report here genome and transcriptome analyses of Colletotrichum higginsianum infecting Arabidopsis thaliana and Colletotrichum graminicola infecting maize. Comparative genomics showed that both fungi have large sets of pathogenicity-related genes, but families of genes encoding secreted effectors, pectin-degrading enzymes, secondary metabolism enzymes, transporters and peptidases are expanded in C. higginsianum. Genome-wide expression profiling revealed that these genes are transcribed in successive waves that are linked to pathogenic transitions: effectors and secondary metabolism enzymes are induced before penetration and during biotrophy, whereas most hydrolases and transporters are upregulated later, at the switch to necrotrophy. Our findings show that preinvasion perception of plant-derived signals substantially reprograms fungal gene expression and indicate previously unknown functions for particular fungal cell types.
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Affiliation(s)
- Richard J O'Connell
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne, Germany.
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Affiliation(s)
- Martin B. Dickman
- Borlaug Advanced Research Center, Texas A&M University, College Station, Texas, United States of America
- Department of Plant Pathology & Microbiology, Texas A&M University, College Station, Texas, United States of America
| | - Paul de Figueiredo
- Borlaug Advanced Research Center, Texas A&M University, College Station, Texas, United States of America
- Department of Plant Pathology & Microbiology, Texas A&M University, College Station, Texas, United States of America
- Department of Veterinary Pathobiology, Texas A&M University, College Station, Texas, United States of America
- Department of Microbial and Molecular Pathogenesis, Texas A&M Health Science Center, College Station, Texas, United States of America
- * E-mail:
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Paul JY, Becker DK, Dickman MB, Harding RM, Khanna HK, Dale JL. Apoptosis-related genes confer resistance to Fusarium wilt in transgenic 'Lady Finger' bananas. Plant Biotechnol J 2011; 9:1141-1148. [PMID: 21819535 DOI: 10.1111/j.1467-7652.2011.00639.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense (Foc), is one of the most devastating diseases of banana (Musa spp.). Apart from resistant cultivars, there are no effective control measures for the disease. We investigated whether the transgenic expression of apoptosis-inhibition-related genes in banana could be used to confer disease resistance. Embryogenic cell suspensions of the banana cultivar, 'Lady Finger', were stably transformed with animal genes that negatively regulate apoptosis, namely Bcl-xL, Ced-9 and Bcl-2 3' UTR, and independently transformed plant lines were regenerated for testing. Following a 12-week exposure to Foc race 1 in small-plant glasshouse bioassays, seven transgenic lines (2 × Bcl-xL, 3 × Ced-9 and 2 × Bcl-2 3' UTR) showed significantly less internal and external disease symptoms than the wild-type susceptible 'Lady Finger' banana plants used as positive controls. Of these, one Bcl-2 3' UTR line showed resistance that was equivalent to that of wild-type Cavendish bananas that were included as resistant negative controls. Further, the resistance of this line continued for 23-week postinoculation at which time the experiment was terminated. Using TUNEL assays, Foc race 1 was shown to induce apoptosis-like features in the roots of wild-type 'Lady Finger' plants consistent with a necrotrophic phase in the life cycle of this pathogen. This was further supported by the observed reduction in these effects in the roots of the resistant Bcl-2 3' UTR-transgenic line. This is the first report on the generation of transgenic banana plants with resistance to Fusarium wilt.
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Affiliation(s)
- Jean-Yves Paul
- Centre for Tropical Crops and Biocommodities, Faculty of Science and Technology, Queensland University of Technology, Brisbane, Qld, Australia
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Bar-Dror T, Dermastia M, Kladnik A, Žnidarič MT, Novak MP, Meir S, Burd S, Philosoph-Hadas S, Ori N, Sonego L, Dickman MB, Lers A. Programmed cell death occurs asymmetrically during abscission in tomato. Plant Cell 2011; 23:4146-63. [PMID: 22128123 PMCID: PMC3246325 DOI: 10.1105/tpc.111.092494] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Revised: 10/11/2011] [Accepted: 11/17/2011] [Indexed: 05/03/2023]
Abstract
Abscission occurs specifically in the abscission zone (AZ) tissue as a natural stage of plant development. Previously, we observed delay of tomato (Solanum lycopersicum) leaf abscission when the LX ribonuclease (LX) was inhibited. The known association between LX expression and programmed cell death (PCD) suggested involvement of PCD in abscission. In this study, hallmarks of PCD were identified in the tomato leaf and flower AZs during the late stage of abscission. These included loss of cell viability, altered nuclear morphology, DNA fragmentation, elevated levels of reactive oxygen species and enzymatic activities, and expression of PCD-associated genes. Overexpression of antiapoptotic proteins resulted in retarded abscission, indicating PCD requirement. PCD, LX, and nuclease gene expression were visualized primarily in the AZ distal tissue, demonstrating an asymmetry between the two AZ sides. Asymmetric expression was observed for genes associated with cell wall hydrolysis, leading to AZ, or associated with ethylene biosynthesis, which induces abscission. These results suggest that different abscission-related processes occur asymmetrically between the AZ proximal and distal sides. Taken together, our findings identify PCD as a key mechanism that occurs asymmetrically during normal progression of abscission and suggest an important role for LX in this PCD process.
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Affiliation(s)
- Tal Bar-Dror
- Department of Postharvest Science of Fresh Produce, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Robert H. Smith Faculty of Agriculture, Food, and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel
| | - Marina Dermastia
- Department of Biotechnology and Systems Biology, National Institute of Biology, SI-1000 Ljubljana, Slovenia
| | - Aleš Kladnik
- Department of Biology, Biotechnical Faculty, University of Ljubljana, SI-1000 Ljubljana, Slovenia
| | - Magda Tušek Žnidarič
- Department of Biotechnology and Systems Biology, National Institute of Biology, SI-1000 Ljubljana, Slovenia
| | - Maruša Pompe Novak
- Department of Biotechnology and Systems Biology, National Institute of Biology, SI-1000 Ljubljana, Slovenia
| | - Shimon Meir
- Department of Postharvest Science of Fresh Produce, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel
| | - Shaul Burd
- Department of Postharvest Science of Fresh Produce, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel
| | - Sonia Philosoph-Hadas
- Department of Postharvest Science of Fresh Produce, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel
| | - Naomi Ori
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Robert H. Smith Faculty of Agriculture, Food, and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel
| | - Lilian Sonego
- Department of Postharvest Science of Fresh Produce, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel
| | - Martin B. Dickman
- Department of Plant Pathology and Microbiology, Institute for Plant Genomics and Biotechnology, Texas A&M University, College Station, Texas 77843
| | - Amnon Lers
- Department of Postharvest Science of Fresh Produce, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel
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Williams B, Kabbage M, Kim HJ, Britt R, Dickman MB. Tipping the balance: Sclerotinia sclerotiorum secreted oxalic acid suppresses host defenses by manipulating the host redox environment. PLoS Pathog 2011; 7:e1002107. [PMID: 21738471 PMCID: PMC3128121 DOI: 10.1371/journal.ppat.1002107] [Citation(s) in RCA: 279] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Accepted: 04/22/2011] [Indexed: 12/21/2022] Open
Abstract
Sclerotinia sclerotiorum is a necrotrophic ascomycete fungus with an extremely broad host range. This pathogen produces the non-specific phytotoxin and key pathogenicity factor, oxalic acid (OA). Our recent work indicated that this fungus and more specifically OA, can induce apoptotic-like programmed cell death (PCD) in plant hosts, this induction of PCD and disease requires generation of reactive oxygen species (ROS) in the host, a process triggered by fungal secreted OA. Conversely, during the initial stages of infection, OA also dampens the plant oxidative burst, an early host response generally associated with plant defense. This scenario presents a challenge regarding the mechanistic details of OA function; as OA both suppresses and induces host ROS during the compatible interaction. In the present study we generated transgenic plants expressing a redox-regulated GFP reporter. Results show that initially, Sclerotinia (via OA) generates a reducing environment in host cells that suppress host defense responses including the oxidative burst and callose deposition, akin to compatible biotrophic pathogens. Once infection is established however, this necrotroph induces the generation of plant ROS leading to PCD of host tissue, the result of which is of direct benefit to the pathogen. In contrast, a non-pathogenic OA-deficient mutant failed to alter host redox status. The mutant produced hypersensitive response-like features following host inoculation, including ROS induction, callose formation, restricted growth and cell death. These results indicate active recognition of the mutant and further point to suppression of defenses by the wild type necrotrophic fungus. Chemical reduction of host cells with dithiothreitol (DTT) or potassium oxalate (KOA) restored the ability of this mutant to cause disease. Thus, Sclerotinia uses a novel strategy involving regulation of host redox status to establish infection. These results address a long-standing issue involving the ability of OA to both inhibit and promote ROS to achieve pathogenic success. Necrotrophic fungal pathogens need to kill plant cells to establish disease and obtain nutrition. While such pathogens are economically important, they are relatively understudied and mechanistic details important for pathogenic success are limited. Sclerotinia sclerotiorum is a necrotrophic ascomycete fungus that infects virtually all dicotyledonous (>400 species) plants. Our data indicate that oxalic acid production and modulation of reactive oxygen species (ROS) are key components for the successful interaction of this fungus with the host plant. Here, we use a GFP regulated reporter system to analyze the host redox status during infections with wild type and a non-pathogenic oxalic acid (OA) deficient Sclerotinia mutant. Additionally, we show that secreted OA enables Sclerotinia to hijack the host cell redox machinery, initially creating reducing conditions followed by an oxidizing environment that is necessary for pathogenesis. We also provide evidence that the OA-deficient mutants are actively recognized by the plant resulting in the elicitation of a hypersensitive-like response and resistance. Our study provides insight into how Sclerotinia, and quite possibly other necrotrophic pathogens, co-opt host redox and cell death pathways for successful colonization of the host.
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Affiliation(s)
- Brett Williams
- Institute for Plant Genomics and Biotechnology, Department of Plant Pathology and Microbiology, Texas A&M University, College Station, Texas, United States of America
| | - Mehdi Kabbage
- Institute for Plant Genomics and Biotechnology, Department of Plant Pathology and Microbiology, Texas A&M University, College Station, Texas, United States of America
| | - Hyo-Jin Kim
- Institute for Plant Genomics and Biotechnology, Department of Plant Pathology and Microbiology, Texas A&M University, College Station, Texas, United States of America
| | - Robert Britt
- Institute for Plant Genomics and Biotechnology, Department of Plant Pathology and Microbiology, Texas A&M University, College Station, Texas, United States of America
| | - Martin B. Dickman
- Institute for Plant Genomics and Biotechnology, Department of Plant Pathology and Microbiology, Texas A&M University, College Station, Texas, United States of America
- * E-mail:
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Ye C, Dickman MB, Whitham SA, Payton M, Verchot J. The unfolded protein response is triggered by a plant viral movement protein. Plant Physiol 2011; 156:741-55. [PMID: 21474436 PMCID: PMC3177272 DOI: 10.1104/pp.111.174110] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Accepted: 04/04/2011] [Indexed: 05/17/2023]
Abstract
Infection with Potato virus X (PVX) in Nicotiana benthamiana plants leads to increased transcript levels of several stress-related host genes, including basic-region leucine zipper 60 (bZIP60), SKP1, ER luminal binding protein (BiP), protein disulfide isomerase (PDI), calreticulin (CRT), and calmodulin (CAM). bZIP60 is a key transcription factor that responds to endoplasmic reticulum (ER) stress and induces the expression of ER-resident chaperones (BiP, PDI, CRT, and CAM). SKP1 is a component of SCF (for SKP1-Cullin-F box protein) ubiquitin ligase complexes that target proteins for proteasomal degradation. Expression of PVX TGBp3 from a heterologous vector induces the same set of genes in N. benthamiana and Arabidopsis (Arabidopsis thaliana) leaves. Virus-induced gene silencing was employed to knock down the expression of bZIP60 and SKP1, and the number of infection foci on inoculated leaves was reduced and systemic PVX accumulation was altered. Silencing bZIP60 led to the suppression of BiP and SKP1 transcript levels, suggesting that bZIP60 might be an upstream signal transducer. Overexpression of TGBp3 led to localized necrosis, but coexpression of TGBp3 with BiP abrogated necrosis, demonstrating that the unfolded protein response alleviates ER stress-related cell death. Steady-state levels of PVX replicase and TGBp2 (which reside in the ER) proteins were unaltered by the presence of TGBp3, suggesting that TGBp3 does not contribute to their turnover. Taken together, PVX TGBp3-induced ER stress leads to up-regulation of bZIP60 and unfolded protein response-related gene expression, which may be important to regulate cellular cytotoxicity that could otherwise lead to cell death if viral proteins reach high levels in the ER.
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Affiliation(s)
| | | | | | | | - Jeanmarie Verchot
- Department of Entomology and Plant Pathology (C.Y., J.V.) and Department of Statistics (M.P.), Oklahoma State University, Stillwater, Oklahoma 74078; Institute for Plant Genomics and Biotechnology, Department of Plant Pathology and Microbiology, Texas A&M University, College Station, Texas 77843 (M.B.D.); Department of Plant Pathology, Iowa State University, Ames, Iowa 50011 (S.A.W.)
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Kim KS, Min JY, Dickman MB. Oxalic acid is an elicitor of plant programmed cell death during Sclerotinia sclerotiorum disease development. Mol Plant Microbe Interact 2008; 21:605-12. [PMID: 18393620 DOI: 10.1094/mpmi-21-5-0605] [Citation(s) in RCA: 209] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Accumulating evidence supports the idea that necrotrophic plant pathogens interact with their hosts by controlling cell death. Sclerotinia sclerotiorum is a necrotrophic ascomycete fungus with a broad host range (>400 species). Previously, we established that oxalic acid (OA) is an important pathogenicity determinant of this fungus. In this report, we describe a mechanism by which oxalate contributes to the pathogenic success of this fungus; namely, that OA induces a programmed cell death (PCD) response in plant tissue that is required for disease development. This response exhibits features associated with mammalian apoptosis, including DNA laddering and TUNEL reactive cells. Fungal mutants deficient in OA production are nonpathogenic, and apoptotic-like characteristics are not observed following plant inoculation. The induction of PCD by OA is independent of the pH-reducing abilities of this organic acid, which is required for sclerotial development. Moreover, oxalate also induces increased reactive oxygen species (ROS) levels in the plant, which correlate to PCD. When ROS induction is inhibited, apoptotic-like cell death induced by OA does not occur. Taken together, we show that Sclerotinia spp.-secreted OA is an elicitor of PCD in plants and is responsible for induction of apoptotic-like features in the plant during disease development. This PCD is essential for fungal pathogenicity and involves ROS. Thus, OA appears to function by triggering in the plant pathways responsible for PCD. Further, OA secretion by Sclerotinia spp. is not directly toxic but, more subtly, may function as a signaling molecule.
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Affiliation(s)
- Kyoung Su Kim
- Institute for Plant Genomics and Biotechnology, Department of Plant Pathology and Microbiology, Texas A&M University, College Station, Texas 77843, USA
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Krishnan N, Dickman MB, Becker DF. Proline modulates the intracellular redox environment and protects mammalian cells against oxidative stress. Free Radic Biol Med 2008; 44:671-81. [PMID: 18036351 PMCID: PMC2268104 DOI: 10.1016/j.freeradbiomed.2007.10.054] [Citation(s) in RCA: 248] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2007] [Revised: 10/25/2007] [Accepted: 10/30/2007] [Indexed: 10/22/2022]
Abstract
The potential of proline to suppress reactive oxygen species (ROS) and apoptosis in mammalian cells was tested by manipulating intracellular proline levels exogenously and endogenously by overexpression of proline metabolic enzymes. Proline was observed to protect cells against H(2)O(2), tert-butyl hydroperoxide, and a carcinogenic oxidative stress inducer but was not effective against superoxide generators such as menadione. Oxidative stress protection by proline requires the secondary amine of the pyrrolidine ring and involves preservation of the glutathione redox environment. Overexpression of proline dehydrogenase (PRODH), a mitochondrial flavoenzyme that oxidizes proline, resulted in 6-fold lower intracellular proline content and decreased cell survival relative to control cells. Cells overexpressing PRODH were rescued by pipecolate, an analog that mimics the antioxidant properties of proline, and by tetrahydro-2-furoic acid, a specific inhibitor of PRODH. In contrast, overexpression of the proline biosynthetic enzymes Delta(1)-pyrroline-5-carboxylate (P5C) synthetase (P5CS) and P5C reductase (P5CR) resulted in 2-fold higher proline content, significantly lower ROS levels, and increased cell survival relative to control cells. In different mammalian cell lines exposed to physiological H(2)O(2) levels, increased endogenous P5CS and P5CR expression was observed, indicating that upregulation of proline biosynthesis is an oxidative stress response.
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Affiliation(s)
- Navasona Krishnan
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, NE 68588
| | - Martin B. Dickman
- Institute for Plant Genomics and Biotechnology, Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843
| | - Donald F. Becker
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, NE 68588
- Corresponding Author: Department of Biochemistry, University of Nebraska, N258 Beadle Center, Lincoln, NE 68588, Tel. 402-472-9652; Fax. 402-472-7842;
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Khanna HK, Paul JY, Harding RM, Dickman MB, Dale JL. Inhibition of Agrobacterium-induced cell death by antiapoptotic gene expression leads to very high transformation efficiency of banana. Mol Plant Microbe Interact 2007; 20:1048-54. [PMID: 17849707 DOI: 10.1094/mpmi-20-9-1048] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The death of plant cells in culture following exposure to Agrobacterium tumefaciens remains a major obstacle in developing Agrobacterium-mediated transformation into a highly efficient genotype-independent technology. Here, we present evidence that A. tumefaciens exposure induces cell death in banana cell suspensions. More than 90% of embryogenic banana cells died after exposure to A. tumefaciens and cell death was accompanied by a subset of features associated with apoptosis in mammalian cells, including DNA laddering, fragmentation, and formation of apoptotic-like bodies. Importantly, these cellular responses were inhibited in cells expressing the animal antiapoptosis genes Bcl-xL, Bcl-2 3' untranslated region, and CED-9. Inhibition of cell death resulted in up to 90% of cell clumps transformed with Bcl-xL, a 100-fold enhancement over vector controls, approaching the transformation and regeneration of every "transformable" cell. Similar results using sugarcane, a crop plant known for recalcitrance to Agrobacterium transformation, suggest that antiapoptosis genes may inhibit these phenomena and increase the transformation frequency of many recalcitrant plant species, including the major monocot cereal crop plants. Evidence of inhibition of plant cell death by cross-kingdom antiapoptotic genes also contributes to the growing evidence that genes for control of programmed cell death are conserved across wide evolutionary distances, even though these mechanisms are not well understood in plants.
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Affiliation(s)
- Harjeet K Khanna
- Institute of Health and Biomedical Innovation, Queensland University of Technology, 2 George St., Brisbane Queensland, 4001, Australia.
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Chen C, Wanduragala S, Becker DF, Dickman MB. Tomato QM-like protein protects Saccharomyces cerevisiae cells against oxidative stress by regulating intracellular proline levels. Appl Environ Microbiol 2006; 72:4001-6. [PMID: 16751508 PMCID: PMC1489650 DOI: 10.1128/aem.02428-05] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Exogenous proline can protect cells of Saccharomyces cerevisiae from oxidative stress. We altered intracellular proline levels by overexpressing the proline dehydrogenase gene (PUT1) of S. cerevisiae. Put1p performs the first enzymatic step of proline degradation in S. cerevisiae. Overexpression of Put1p results in low proline levels and hypersensitivity to oxidants, such as hydrogen peroxide and paraquat. A put1-disrupted yeast mutant deficient in Put1p activity has increased protection from oxidative stress and increased proline levels. Following a conditional life/death screen in yeast, we identified a tomato (Lycopersicon esculentum) gene encoding a QM-like protein (tQM) and found that stable expression of tQM in the Put1p-overexpressing strain conferred protection against oxidative damage from H2O2, paraquat, and heat. This protection was correlated with reactive oxygen species (ROS) reduction and increased proline accumulation. A yeast two-hybrid system assay was used to show that tQM physically interacts with Put1p in yeast, suggesting that tQM is directly involved in modulating proline levels. tQM also can rescue yeast from the lethality mediated by the mammalian proapoptotic protein Bax, through the inhibition of ROS generation. Our results suggest that tQM is a component of various stress response pathways and may function in proline-mediated stress tolerance in plants.
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Affiliation(s)
- Changbin Chen
- Institute for Plant Genomics and Biotechnology, Department of Plant Pathology and Microbiology, Texas A&M University, 2123 TAMU, College Station, TX 77843, USA
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Doukhanina EV, Chen S, van der Zalm E, Godzik A, Reed J, Dickman MB. Identification and Functional Characterization of the BAG Protein Family in Arabidopsis thaliana. J Biol Chem 2006; 281:18793-801. [PMID: 16636050 DOI: 10.1074/jbc.m511794200] [Citation(s) in RCA: 142] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The genes that control mammalian programmed cell death are conserved across wide evolutionary distances. Although plant cells can undergo apoptosis-like cell death, plant homologs of mammalian regulators of apoptosis have, in general, not been found. This is in part due to the lack of primary sequence conservation between animal and putative plant regulators of apoptosis. Thus, alternative approaches beyond sequence similarities are required to find functional plant homologs of apoptosis regulators. Here, we present the results of using advanced bioinformatic tools to uncover the Arabidopsis family of BAG proteins. The mammalian BAG (Bcl-2-associated athanogene) proteins are a family of chaperone regulators that modulate a number of diverse processes ranging from proliferation to growth arrest and cell death. Such proteins are distinguished by a conserved BAG domain that directly interacts with Hsp70 and Hsc70 proteins to regulate their activity. Our searches of the Arabidopsis thaliana genome sequence revealed seven homologs of the BAG protein family. We further show that plant BAG family members are also multifunctional and remarkably similar to their animal counterparts, as they regulate apoptosis-like processes ranging from pathogen attack to abiotic stress and development.
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Affiliation(s)
- Elena V Doukhanina
- Department of Plant Pathology, University of Nebraska, Lincoln, Nebraska 68583, USA
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Chen C, Ha YS, Min JY, Memmott SD, Dickman MB. Cdc42 is required for proper growth and development in the fungal pathogen Colletotrichum trifolii. Eukaryot Cell 2006; 5:155-66. [PMID: 16400178 PMCID: PMC1360247 DOI: 10.1128/ec.5.1.155-166.2006] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Cdc42 is a highly conserved small GTP-binding protein that is involved in regulating morphogenesis in eukaryotes. In this study, we isolated and characterized a highly conserved Cdc42 gene from Colletotrichum trifolii (CtCdc42), a fungal pathogen of alfalfa. CtCdc42 is, at least in part, functionally equivalent to Saccharomyces cerevisiae Cdc42p, since it restores the temperature-sensitive phenotype of a yeast Cdc42p mutant. Inhibition of CtCdc42 by expression of an antisense CtCdc42 or a dominant negative form of CtCdc42 (DN Cdc42) resulted in appressorium differentiation under noninductive conditions, suggesting that CtCdc42 negatively regulates pathogenic development in this fungus. We also examined the possible linkage between CtCdc42 and Ras signaling. Expression of a dominant active Cdc42 (DA Cdc42) in C. trifolii leads to aberrant hyphal growth under nutrient-limiting conditions. This phenotype was similar to that of our previously reported dominant active Ras (DA Ras) mutant. Also consistent with our observations of the DA Ras mutant, high levels of reactive oxygen species (ROS) were observed in the DA Cdc42 mutant, and proline restored the wild-type phenotype. Moreover, overexpression of DN Cdc42 resulted in a significant decrease in spore germination, virtually no hyphal branching, and earlier sporulation, again similar to what we observed in a dominant negative Ras (DN Ras) mutant strain. Interestingly, coexpression of DA Cdc42 with DN Ras resulted in germination rates close to wild-type levels, while coexpression of DN Cdc42 with the DA Ras mutant restored the wild-type phenotype. These data suggest that CtCdc42 is positioned as a downstream effector of CtRas to regulate spore germination and pathogenic development.
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Affiliation(s)
- Changbin Chen
- Department of Plant Pathology, 406 Plant Sciences Hall, University of Nebraska--Lincoln, Lincoln, Nebraska 68583-0722, USA
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Abstract
Recent advances in sequencing technologies have led to a remarkable increase in the number of sequenced fungal genomes. Several important plant pathogenic fungi are among those that have been sequenced or are being sequenced. Additional fungal pathogens are likely to be sequenced in the near future. Analysis of the available genomes has provided useful information about genes that may be important for plant infection and colonization. Genome features, such as repetitive sequences, telomeres, conserved syntenic blocks, and expansion of pathogenicity-related genes, are discussed in detail with Magnaporthe oryzae (M. grisea) and Fusarium graminearum as examples. Functional and comparative genomic studies in plant pathogenic fungi, although still in the early stages and limited to a few pathogens, have enormous potential to improve our understanding of the molecular mechanisms involved in host-pathogen interactions. Development of advanced genomics tools and infrastructure is critical for efficient utilization of the vast wealth of available genome sequence information and will form a solid foundation for systems biology studies of plant pathogenic fungi.
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Affiliation(s)
- Jin-Rong Xu
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907, USA.
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Scheffer J, Chen C, Heidrich P, Dickman MB, Tudzynski P. A CDC42 homologue in Claviceps purpurea is involved in vegetative differentiation and is essential for pathogenicity. Eukaryot Cell 2005; 4:1228-38. [PMID: 16002649 PMCID: PMC1168960 DOI: 10.1128/ec.4.7.1228-1238.2005] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Claviceps purpurea, a biotrophic pathogen of cereals, has developed a unique pathogenic strategy including an extended period of unbranched directed growth in the host's style and ovarian tissue to tap the vascular system. Since the small GTPase Cdc42 has been shown to be involved in cytoskeleton organization and polarity in other fungi, we investigated the role of Cdc42 in the development and pathogenicity of C. purpurea. Expression of heterologous dominant-active (DA) and dominant-negative (DN) alleles of Colletotrichum trifolii in a wild strain of C. purpurea had significant impact on vegetative differentiation: whereas DA Ctcdc42 resulted in loss of conidiation and in aberrant cell shape, expression of DN Ctcdc42 stimulated branching and conidiation. Deletion of the endogenous Cpcdc42 gene was not lethal but led to a phenotype comparable to that of DN Ctcdc42 transformants. DeltaCpcdc42 mutants were nonpathogenic; i.e., they induced no disease symptoms. Cytological analysis (light microscopy and electron microscopy) revealed that the mutants can penetrate and invade the stylar tissue. However, invasive growth was arrested in an early stage, presumably induced by plant defense reactions (necrosis or increased production of reactive oxygen species), which were never observed in wild-type infection. The data show a significant impact of Cpcdc42 on vegetative differentiation and pathogenicity in C. purpurea.
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Affiliation(s)
- Jan Scheffer
- Institut für Botanik, Westfälische Wilhelms-Universität, Schlossgarten 3, D-48149 Münster, Germany
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38
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Abstract
Sclerotinia sclerotiorum is a filamentous ascomycete phytopathogen able to infect an extremely wide range of cultivated plants. Our previous studies have shown that increases in cAMP levels result in the impairment of the development of the sclerotium, a highly differentiated structure important in the disease cycle of this fungus. cAMP also inhibits the activation of a S. sclerotiorum mitogen-activated protein kinase (MAPK), which we have previously shown to be required for sclerotial maturation; thus cAMP-mediated sclerotial inhibition is modulated through MAPK. However, the mechanism(s) by which cAMP inhibits MAPK remains unclear. Here we demonstrate that a protein kinase A (PKA)-independent signalling pathway probably mediates MAPK inhibition by cAMP. Expression of a dominant negative form of Ras, an upstream activator of the MAPK pathway, also inhibited sclerotial development and MAPK activation, suggesting that a conserved Ras/MAPK pathway is required for sclerotial development. Evidence from bacterial toxins that specifically inhibit the activity of small GTPases, suggested that Rap-1 or Ras is involved in cAMP action. The Rap-1 inhibitor, GGTI-298, restored MAPK activation in the presence of cAMP, further suggesting that Rap-1 is responsible for cAMP-dependent MAPK inhibition. Importantly, inhibition of Rap-1 is able to restore sclerotial development blocked by cAMP. Our results suggest a novel mechanism involving the requirement of Ras/MAPK pathway for sclerotial development that is negatively regulated by a PKA-independent cAMP signalling pathway. Cross-talk between these two pathways is mediated by Rap-1.
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Affiliation(s)
- Changbin Chen
- Department of Plant Pathology, University of Nebraska-Lincoln, Nebraska, NE 68583, USA
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Chen C, Dickman MB. Proline suppresses apoptosis in the fungal pathogen Colletotrichum trifolii. Proc Natl Acad Sci U S A 2005; 102:3459-64. [PMID: 15699356 PMCID: PMC552905 DOI: 10.1073/pnas.0407960102] [Citation(s) in RCA: 246] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2004] [Accepted: 01/07/2005] [Indexed: 01/07/2023] Open
Abstract
The role of reactive oxygen species (ROS) in cell communication, control of gene expression, and oxygen sensing is well established. Inappropriate regulation of ROS levels can damage cells, resulting in a diseased state. In Colletotrichum trifolii, a fungal pathogen of alfalfa, the mutationally activated oncogenic fungal Ras (DARas) elevates levels of ROS, causing abnormal fungal growth and development and eventual apoptotic-like cell death but only when grown under nutrient-limiting conditions. Remarkably, restoration to the wild-type phenotype requires only proline. Here, we describe a generally unrecognized function of proline: its ability to function as a potent antioxidant and inhibitor of programmed cell death. Addition of proline to DARas mutant cells effectively quenched ROS levels and prevented cell death. Treating cells with inhibitors of ROS production yielded similar results. In addition, proline protected wild-type C. trifolii cells against various lethal stresses, including UV light, salt, heat, and hydrogen peroxide. These observations appear to be general because proline also protected yeast cells from lethal levels of the ROS-generating herbicide methyl viologen (paraquat), suggesting a common protective role for proline in response to oxidative stress. The ability of proline to scavenge intracellular ROS and inhibit ROS-mediated apoptosis may be an important and broad-based function of this amino acid in responding to cellular stress, in addition to its well established role as an osmolyte.
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Affiliation(s)
- Changbin Chen
- Department of Plant Pathology, University of Nebraska, 406 Plant Sciences Hall, Lincoln, NE 68583-0722, USA
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Chen S, Dickman MB. Bcl-2 family members localize to tobacco chloroplasts and inhibit programmed cell death induced by chloroplast-targeted herbicides. J Exp Bot 2004; 55:2617-23. [PMID: 15475374 DOI: 10.1093/jxb/erh275] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
In mammalian cells, apoptosis is often mediated via organelles. While apoptotic-like cell death occurs in plants, the mechanistic details are unresolved. Transgenic tobacco plants have been generated that harbour selected animal anti-apoptotic genes. Subcellular fractionation followed by western blot analysis indicated that chloroplasts serve as a location for these animal anti-apoptotic proteins in addition to the established mitochondrial location. To explore the functional significance of this observation, tobacco plants were treated with three chloroplast-directed herbicides. Wild-type plants died and exhibited features associated with apoptosis. Transgenic plants survived and did not show any apoptotic-like characteristics. Moreover, the herbicide-induced apoptotic-like cell death was light requiring. It was concluded that chloroplasts may be involved in mediating certain types of plant programmed cell death.
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Affiliation(s)
- Shaorong Chen
- Department of Plant Pathology, 406 Plant Sciences Hall, University of Nebraska, Lincoln, NE 68583-0722, USA
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41
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Chen S, Vaghchhipawala Z, Li W, Asard H, Dickman MB. Tomato phospholipid hydroperoxide glutathione peroxidase inhibits cell death induced by Bax and oxidative stresses in yeast and plants. Plant Physiol 2004; 135:1630-41. [PMID: 15235116 PMCID: PMC519077 DOI: 10.1104/pp.103.038091] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2003] [Revised: 03/30/2004] [Accepted: 03/30/2004] [Indexed: 05/19/2023]
Abstract
Using a conditional life or death screen in yeast, we have isolated a tomato (Lycopersicon esculentum) gene encoding a phospholipid hydroperoxide glutathione peroxidase (LePHGPx). The protein displayed reduced glutathione-dependent phospholipid hydroperoxide peroxidase activity, but differs from counterpart mammalian enzymes that instead contain an active seleno-Cys. LePHGPx functioned as a cytoprotector in yeast (Saccharomyces cerevisiae), preventing Bax, hydrogen peroxide, and heat stress induced cell death, while also delaying yeast senescence. When tobacco (Nicotiana tabacum) leaves were exposed to lethal levels of salt and heat stress, features associated with mammalian apoptosis were observed. Importantly, transient expression of LePHGPx protected tobacco leaves from salt and heat stress and suppressed the apoptotic-like features. As has been reported, conditional expression of Bax was lethal in tobacco, resulting in tissue collapse and membrane permeability to Evans blue. When LePHGPx was coexpressed with Bax, little cell death and no vital staining were observed. Moreover, stable expression of LePHGPx in tobacco conferred protection against the fungal phytopathogen Botrytis cinerea. Taken together, our data indicated that LePHGPx can protect plant tissue from a variety of stresses. Moreover, functional screens in yeast are a viable tool for the identification of plant genes that regulate cell death.
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Affiliation(s)
- Shaorong Chen
- Department of Plant Pathology, University of Nebraska, Lincoln, Nebraska 68583, USA
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Chen C, Harel A, Gorovoits R, Yarden O, Dickman MB. MAPK regulation of sclerotial development in Sclerotinia sclerotiorum is linked with pH and cAMP sensing. Mol Plant Microbe Interact 2004; 17:404-413. [PMID: 15077673 DOI: 10.1094/mpmi.2004.17.4.404] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Sclerotial development is fundamental to the disease cycle of the omnivorous broad host range fungal phytopathogen Sclerotinia sclerotiorum. We have isolated a highly conserved homolog of ERK-type mitogen-activated protein kinases (MAPKs) from S. sclerotiorum (Smk1) and have demonstrated that Smk1 is required for sclerotial development. The smk1 transcription and MAPK enzyme activity are induced dramatically during sclerotiogenesis, especially during the production of sclerotial initials. When PD98059 (a specific inhibitor of the activation of MAPK by MAPK kinase) was applied to differentiating cultures or when antisense expression of smk1 was induced, sclerotial maturation was impaired. The smk1 transcript levels were highest under acidic pH conditions, suggesting that Smk1 regulates sclerotial development via a pH-dependent signaling pathway, involving the accumulation of oxalic acid, a previously identified pathogenicity factor that functions at least in part by reducing pH. Addition of cyclic AMP (cAMP) inhibited smk1 transcription, MAPK activation, and sclerotial development. Thus, S. sclerotiorum can coordinate environmental signals (such as pH) to trigger a signaling pathway mediated by Smk1 to induce sclerotia formation, and this pathway is negatively regulated by cAMP.
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Affiliation(s)
- Changbin Chen
- Department of Plant Pathology, 406 Plant Sciences Hall, University of Nebraska-Lincoln, 68583-0722, USA
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Chen C, Dickman MB. Dominant active Rac and dominant negative Rac revert the dominant active Ras phenotype in Colletotrichum trifolii by distinct signalling pathways. Mol Microbiol 2004; 51:1493-507. [PMID: 14982641 DOI: 10.1111/j.1365-2958.2003.03932.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The small G-protein superfamily is an evolutionarily conserved group of GTPases that regulate diverse signalling pathways including pathways for growth and development in eukaryotes. Previously, we showed that dominant active mutation in the unique Ras gene (DARas) of the fungal phytopathogen Colletotrichum trifolii displays a nutrient-dependent phenotype affecting polarity, growth and differentiation. Signalling via the MAP kinase pathway is significantly impaired in this mutant as well. Here we describe the cloning and functional characterization of Rac (Ct-Rac1), a member of the Rho family of G proteins. Ct-Rac1 expression is downregulated by DARas under limiting nutrition. Co-expression of DARas with dominant active Rac (DARac) stimulates MAPK activation and restores the wild-type phenotype. Inhibition of MAPK activation suppresses phenotypic restoration suggesting Rac-mediated MAPK activation is responsible for reversion to the wild-type phenotype. We also examined the role of reactive oxygen species (ROS) in these genetic backgrounds. The DARas mutant strain generates high levels of ROS as determined by DCFH-DA fluorescence. Co-expression with DNRac decreases ROS generation to wild-type levels and restores normal fungal growth and development. Pretreatment of DARas with antioxidants or a cytosolic phospholipase A2 inhibitor also restores the wild-type phenotype. These findings suggest that Ras-mediated ROS generation is dependent on a Rac-cPLA(2)-linked signalling pathway. Taken together, this study provides evidence that Rac functions to restore the hyphal morphology of DARas by regulating MAPK activation and intracellular ROS generation.
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Affiliation(s)
- Changbin Chen
- Department of Plant Pathology, University of Nebraska-Lincoln, Nebraska 68583, USA
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Jamir Y, Guo M, Oh HS, Petnicki-Ocwieja T, Chen S, Tang X, Dickman MB, Collmer A, Alfano JR. Identification of Pseudomonas syringae type III effectors that can suppress programmed cell death in plants and yeast. Plant J 2004; 37:554-65. [PMID: 14756767 DOI: 10.1046/j.1365-313x.2003.01982.x] [Citation(s) in RCA: 213] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The Pseudomonas syringae pv. tomato DC3000 type III secretion system (TTSS) is required for bacterial pathogenicity on plants and elicitation of the hypersensitive response (HR), a programmed cell death (PCD) that occurs on resistant plants. Cosmid pHIR11 enables non-pathogens to elicit an HR dependent upon the TTSS and the effector HopPsyA. We used pHIR11 to determine that effectors HopPtoE, avirulence AvrPphEPto, AvrPpiB1Pto, AvrPtoB, and HopPtoF could suppress a HopPsyA-dependent HR on tobacco and Arabidopsis. Mixed inoculum and Agrobacterium-mediated transient expression experiments confirmed that suppressor action occurred within plant cells. These suppressors, with the exception of AvrPpiB1Pto, inhibited the expression of the tobacco pathogenesis-related (PR) gene PR1a. DC3000 suppressor mutants elicited an enhanced HR consistent with these mutants lacking an HR suppressor. Additionally, HopPtoG was identified as a suppressor on the basis of an enhanced HR produced by a hopPtoG mutant. Remarkably, these proteins functioned to inhibit the ability of the pro-apoptotic protein, Bax to induce PCD in plants and yeast, indicating that these effectors function as anti-PCD proteins in a trans-kingdom manner. The high proportion of effectors that suppress PCD suggests that suppressing plant immunity is one of the primary roles for DC3000 effectors and a central requirement for P. syringae pathogenesis.
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Affiliation(s)
- Yashitola Jamir
- Plant Science Initiative and Department of Plant Pathology, University of Nebraska, Lincoln, NE 68588-0660, USA
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Abstract
The shared features between plant and animal programmed cell death are becoming increasingly apparent. In this study, human Bcl-2, an anti-apoptotic member of the Bcl-2 family of cell death regulators, was stably expressed in tobacco. Previously, we have shown that such plants were resistant/tolerant to several necrotrophic fungal pathogens. In this study, we show that transgenic plants are protected by several lethal abiotic stresses including heat, cold, menadione and hydrogen peroxide. Importantly, wild type tobacco, exposed to these treatments, not only died but during the death process exhibited features associated with mammalian apoptosis including DNA laddering, fragmentation, and the development of apoptotic bodies. These features were not observed in viable transgenic tobacco. Thus, abiotic stress induced cell death in plants can be accompanied by apoptotic-like features that are inhibited by expression of Bcl-2. These observations add to the growing body of evidence indicating trans-kingdom conservation of programmed cell death mechanisms.
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Affiliation(s)
- Wei Li
- Department of Plant Pathology, 406 Plant Sciences Hall, University of Nebraska, Lincoln, NE 68583, USA
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Abstract
Ras is a small monomeric GTP binding protein that transduces signals for growth and differentiation of eukaryotic organisms. Previously, a unique ras gene, designated Ct-ras, was cloned from the alfalfa fungal phytopathogen, Colletotrichum trifolii. Expression of Ct-Ras in mouse fibroblast cells (NIH3T3) demonstrated that Ct-ras is functionally similar to the mammalian ras genes since activating mutations of Ct-ras caused oncogenic phenotypes in nu/nu mice, including tumors. In C. trifolii, activated 'oncogenic' Ras (Val2) induced abnormal hyphal proliferation, defects in polarized growth and significantly reduced differentiation such as conidiation and appressorium formation in a nutrient dependent manner. Gene disruption of ct-ras was lethal. To further evaluate the function of Ct-Ras in C. trifolii, three different approaches were used: overexpression of cytosolic Ras by CAAX box deletion; expression of dominant negative Ct-RasT22N; and antisense ct-ras expression. Results showed that suppression of Ct-Ras activity significantly decreases fungal germination frequencies and hyphal growth rates. Taken together, these data suggest involvement of Ct-Ras in regulation of fungal cell growth and differentiation.
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Affiliation(s)
- Young-sil Ha
- Department of Plant Pathology, University of Nebraska, 406G Plant Science Hall, Lincoln, NE 68583-0722, USA
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Abstract
Plant pathology has made significant progress over the years, a process that involved overcoming a variety of conceptual and technological hurdles. Descriptive mycology and the advent of chemical plant-disease management have been followed by biochemical and physiological studies of fungi and their hosts. The later establishment of biochemical genetics along with the introduction of DNA-mediated transformation have set the stage for dissection of gene function and advances in our understanding of fungal cell biology and plant-fungus interactions. Currently, with the advent of high-throughput technologies, we have the capacity to acquire vast data sets that have direct relevance to the numerous subdisciplines within fungal biology and pathology. These data provide unique opportunities for basic research and for engineering solutions to important agricultural problems. However, we also are faced with the challenge of data organization and mining to analyze the relationships between fungal and plant genomes and to elucidate the physiological function of pertinent DNA sequences. We present our perspective of fungal biology and agriculture, including administrative and political challenges to plant protection research.
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Affiliation(s)
- O Yarden
- Department of Plant Pathology and Microbiology, Faculty of Agricultural, Food and Environmental Quality Sciences, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
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Abstract
Selected antiapoptotic genes were expressed in baker's yeast (Saccharomyces cerevisiae) to evaluate cytoprotective effects during oxidative stress. When exposed to treatments resulting in the generation of reactive oxygen species (ROS), including H(2)O(2), menadione, or heat shock, wild-type yeast died and exhibited apoptotic-like characteristics, consistent with previous studies. Yeast strains were generated expressing nematode ced-9, human bcl-2, or chicken bcl-xl genes. These transformants tolerated a range of oxidative stresses, did not display features associated with apoptosis, and remained viable under conditions that were lethal to wild-type yeast. Yeast strains expressing a mutant antiapoptotic gene (bcl-2 deltaalpha 5-6), known to be nonfunctional in mammalian cells, were unable to tolerate any of the ROS-generating insults. These data are the first report showing CED-9 has cytoprotective effects against oxidative stress, and add CED-9 to the list of Bcl-2 protein family members that modulate ROS-mediated programmed cell death. In addition, these data indicate that Bcl-2 family members protect wild-type yeast from physiological stresses. Taken together, these data support the concept of the broad evolutionary conservation and functional similarity of the apoptotic processes in eukaryotic organisms.
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Affiliation(s)
- Shao-Rong Chen
- Department of Plant Pathology, University of Nebraska, Lincoln, NE 68583-0722, USA
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Dickman MB, Ha YS, Yang Z, Adams B, Huang C. A protein kinase from Colletotrichum trifolii is induced by plant cutin and is required for appressorium formation. Mol Plant Microbe Interact 2003; 16:411-21. [PMID: 12744512 DOI: 10.1094/mpmi.2003.16.5.411] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
When certain phytopathogenic fungi contact plant surfaces, specialized infection structures (appressoria) are produced that facilitate penetration of the plant external barrier; the cuticle. Recognition of this hydrophobic host surface must be sensed by the fungus, initiating the appropriate signaling pathway or pathways for pathogenic development. Using polymerase chain reaction and primers designed from mammalian protein kinase C sequences (PKC), we have isolated, cloned, and characterized a protein kinase from Colletotrichum trifolii, causal agent of alfalfa anthracnose. Though sequence analysis indicated conserved sequences in mammalian PKC genes, we were unable to induce activity of the fungal protein using known activators of PKC. Instead, we show that the C. trifolii gene, designated LIPK (lipid-induced protein kinase) is induced specifically by purified plant cutin or long-chain fatty acids which are monomeric constituents of cutin. PKC inhibitors prevented appressorium formation and, to a lesser extent, spore germination. Overexpression of LIPK resulted in multiple, abnormally shaped appressoria. Gene replacement of lipk yielded strains which were unable to develop appressoria and were unable to infect intact host plant tissue. However, these mutants were able to colonize host tissue following artificial wounding, resulting in typical anthracnose lesions. Taken together, these data indicate a central role in triggering infection structure formation for this protein kinase, which is induced specifically by components of the plant cuticle. Thus, the fungus is able to sense and use host surface chemistry to induce a protein kinase-mediated pathway that is required for pathogenic development.
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Affiliation(s)
- M B Dickman
- Department of Plant Pathology, University of Nebraska, Lincoln 68583-0722, USA.
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50
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Ahmed A, Crawford T, Gould S, Ha YS, Hollrah M, Noor-E-Ain F, Dickman MB, Dussault PH. Synthesis of (R)- and (S)-10,16-dihydroxyhexadecanoic acid: cutin stereochemistry and fungal activation. Phytochemistry 2003; 63:47-52. [PMID: 12657297 DOI: 10.1016/s0031-9422(03)00003-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The first asymmetric syntheses of the cutin monomers (R)- and (S)-10,16-dihydroxyhexadecanoic acid (10,16-DHPA) and confirmation of (S)(+)-absolute configuration for 10,16-DHPA derived from tomato are reported. The individual DHPA stereoisomers display differences in their ability to activate the fungal pathogen Colletotrichum trifolii.
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Affiliation(s)
- Aqeel Ahmed
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
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