151
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Werner A, Herzog B, Voigt O, Valerius O, Braus GH, Pöggeler S. NBR1 is involved in selective pexophagy in filamentous ascomycetes and can be functionally replaced by a tagged version of its human homolog. Autophagy 2018; 15:78-97. [PMID: 30081713 DOI: 10.1080/15548627.2018.1507440] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Macroautophagy/autophagy is a conserved degradation process in eukaryotic cells involving the sequestration of proteins and organelles within double-membrane vesicles termed autophagosomes. In filamentous fungi, its main purposes are the regulation of starvation adaptation and developmental processes. In contrast to nonselective bulk autophagy, selective autophagy is characterized by cargo receptors, which bind specific cargos such as superfluous organelles, damaged or harmful proteins, or microbes, and target them for autophagic degradation. Herein, using the core autophagy protein ATG8 as bait, GFP-Trap analysis followed by liquid chromatography mass spectrometry (LC/MS) identified a putative homolog of the human autophagy cargo receptor NBR1 (NBR1, autophagy cargo receptor) in the filamentous ascomycete Sordaria macrospora (Sm). Fluorescence microscopy revealed that SmNBR1 colocalizes with SmATG8 at autophagosome-like structures and in the lumen of vacuoles. Delivery of SmNBR1 to the vacuoles requires SmATG8. Both proteins interact in an LC3 interacting region (LIR)-dependent manner. Deletion of Smnbr1 leads to impaired vegetative growth under starvation conditions and reduced sexual spore production under non-starvation conditions. The human NBR1 homolog partially rescues the phenotypic defects of the fungal Smnbr1 deletion mutant. The Smnbr1 mutant can neither use fatty acids as a sole carbon source nor form fruiting bodies under oxidative stress conditions. Fluorescence microscopy revealed that degradation of a peroxisomal reporter protein is impaired in the Smnbr1 deletion mutant. Thus, SmNBR1 is a cargo receptor for pexophagy in filamentous ascomycetes.
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Affiliation(s)
- Antonia Werner
- a Department of Genetics of Eukaryotic Microorganisms, Institute of Microbiology and Genetics , University of Göttingen , Göttingen , Germany
| | - Britta Herzog
- a Department of Genetics of Eukaryotic Microorganisms, Institute of Microbiology and Genetics , University of Göttingen , Göttingen , Germany
| | - Oliver Voigt
- a Department of Genetics of Eukaryotic Microorganisms, Institute of Microbiology and Genetics , University of Göttingen , Göttingen , Germany
| | - Oliver Valerius
- b Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics , University of Göttingen , Göttingen , Germany
| | - Gerhard H Braus
- b Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics , University of Göttingen , Göttingen , Germany.,c Göttingen Center for Molecular Biosciences (GZMB) , University of Göttingen , Göttingen , Germany
| | - Stefanie Pöggeler
- a Department of Genetics of Eukaryotic Microorganisms, Institute of Microbiology and Genetics , University of Göttingen , Göttingen , Germany.,c Göttingen Center for Molecular Biosciences (GZMB) , University of Göttingen , Göttingen , Germany
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152
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Leisner SM, Schoelz JE. Joining the Crowd: Integrating Plant Virus Proteins into the Larger World of Pathogen Effectors. ANNUAL REVIEW OF PHYTOPATHOLOGY 2018; 56:89-110. [PMID: 29852091 DOI: 10.1146/annurev-phyto-080417-050151] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The first bacterial and viral avirulence ( avr) genes were cloned in 1984. Although virus and bacterial avr genes were physically isolated in the same year, the questions associated with their characterization after discovery were very different, and these differences had a profound influence on the narrative of host-pathogen interactions for the past 30 years. Bacterial avr proteins were subsequently shown to suppress host defenses, leading to their reclassification as effectors, whereas research on viral avr proteins centered on their role in the viral infection cycle rather than their effect on host defenses. Recent studies that focus on the multifunctional nature of plant virus proteins have shown that some virus proteins are capable of suppression of the same host defenses as bacterial effectors. This is exemplified by the P6 protein of Cauliflower mosaic virus (CaMV), a multifunctional plant virus protein that facilitates several steps in the infection, including modulation of host defenses. This review highlights the modular structure and multifunctional nature of CaMV P6 and illustrates its similarities to other, well-established pathogen effectors.
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Affiliation(s)
- Scott M Leisner
- Department of Biological Sciences, University of Toledo, Toledo, Ohio 43606, USA
| | - James E Schoelz
- Division of Plant Sciences, University of Missouri, Columbia, Missouri 65211, USA;
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153
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Liu C, Shen W, Yang C, Zeng L, Gao C. Knowns and unknowns of plasma membrane protein degradation in plants. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2018; 272:55-61. [PMID: 29807606 DOI: 10.1016/j.plantsci.2018.04.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 04/02/2018] [Accepted: 04/10/2018] [Indexed: 06/08/2023]
Abstract
Plasma membrane (PM) not only creates a physical barrier to enclose the intracellular compartments but also mediates the direct communication between plants and the ever-changing environment. A tight control of PM protein homeostasis by selective degradation is thus crucial for proper plant development and plant-environment interactions. Accumulated evidences have shown that a number of plant PM proteins undergo clathrin-dependent or membrane microdomain-associated endocytic routes to vacuole for degradation in a cargo-ubiquitination dependent or independent manner. Besides, several trans-acting determinants involved in the regulation of endocytosis, recycling and multivesicular body-mediated vacuolar sorting have been identified in plants. More interestingly, recent findings have uncovered the participation of selective autophagy in PM protein turnover in plants. Although great progresses have been made to identify the PM proteins that undergo dynamic changes in subcellular localizations and to explore the factors that control the membrane protein trafficking, several questions remain to be answered regarding the molecular mechanisms of PM protein degradation in plants. In this short review article, we briefly summarize recent progress in our understanding of the internalization, sorting and degradation of plant PM proteins. More specifically, we focus on discussing the elusive aspects underlying the pathways of PM protein degradation in plants.
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Affiliation(s)
- Chuanliang Liu
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou 510631, China
| | - Wenjin Shen
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou 510631, China
| | - Chao Yang
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou 510631, China
| | - Lizhang Zeng
- Institute for Brain Research and Rehabilitation, South China Normal University, Guangzhou 510631, China
| | - Caiji Gao
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou 510631, China.
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154
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Yang M, Zhang Y, Xie X, Yue N, Li J, Wang XB, Han C, Yu J, Liu Y, Li D. Barley stripe mosaic virus γb Protein Subverts Autophagy to Promote Viral Infection by Disrupting the ATG7-ATG8 Interaction. THE PLANT CELL 2018; 30:1582-1595. [PMID: 29848767 PMCID: PMC6096602 DOI: 10.1105/tpc.18.00122] [Citation(s) in RCA: 105] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 04/18/2018] [Accepted: 05/22/2018] [Indexed: 05/04/2023]
Abstract
Autophagy is a conserved defense strategy against viral infection. However, little is known about the counterdefense strategies of plant viruses involving interference with autophagy. Here, we show that γb protein from Barley stripe mosaic virus (BSMV), a positive single-stranded RNA virus, directly interacts with AUTOPHAGY PROTEIN7 (ATG7). BSMV infection suppresses autophagy, and overexpression of γb protein is sufficient to inhibit autophagy. Furthermore, silencing of autophagy-related gene ATG5 and ATG7 in Nicotiana benthamiana plants enhanced BSMV accumulation and viral symptoms, indicating that autophagy plays an antiviral role in BSMV infection. Molecular analyses indicated that γb interferes with the interaction of ATG7 with ATG8 in a competitive manner, whereas a single point mutation in γb, Tyr29Ala (Y29A), made this protein deficient in the interaction with ATG7, which was correlated with the abolishment of autophagy inhibition. Consistently, the mutant BSMVY29A virus showed reduced symptom severity and viral accumulation. Taken together, our findings reveal that BSMV γb protein subverts autophagy-mediated antiviral defense by disrupting the ATG7-ATG8 interaction to promote plant RNA virus infection, and they provide evidence that ATG7 is a target of pathogen effectors that functions in the ongoing arms race of plant defense and viral counterdefense.
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Affiliation(s)
- Meng Yang
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, P.R. China
| | - Yongliang Zhang
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, P.R. China
| | - Xialin Xie
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, P.R. China
| | - Ning Yue
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, P.R. China
| | - Jinlin Li
- MOE Key Laboratory of Bioinformatics, Center for Plant Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, P.R. China
| | - Xian-Bing Wang
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, P.R. China
| | - Chenggui Han
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, P.R. China
| | - Jialin Yu
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, P.R. China
| | - Yule Liu
- MOE Key Laboratory of Bioinformatics, Center for Plant Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, P.R. China
| | - Dawei Li
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, P.R. China
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155
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Dagdas YF, Pandey P, Tumtas Y, Sanguankiattichai N, Belhaj K, Duggan C, Leary AY, Segretin ME, Contreras MP, Savage Z, Khandare VS, Kamoun S, Bozkurt TO. Host autophagy machinery is diverted to the pathogen interface to mediate focal defense responses against the Irish potato famine pathogen. eLife 2018; 7:37476. [PMID: 29932422 PMCID: PMC6029844 DOI: 10.7554/elife.37476] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 06/21/2018] [Indexed: 12/22/2022] Open
Abstract
During plant cell invasion, the oomycete Phytophthora infestans remains enveloped by host-derived membranes whose functional properties are poorly understood. P. infestans secretes a myriad of effector proteins through these interfaces for plant colonization. Recently we showed that the effector protein PexRD54 reprograms host-selective autophagy by antagonising antimicrobial-autophagy receptor Joka2/NBR1 for ATG8CL binding (Dagdas et al., 2016). Here, we show that during infection, ATG8CL/Joka2 labelled defense-related autophagosomes are diverted toward the perimicrobial host membrane to restrict pathogen growth. PexRD54 also localizes to autophagosomes across the perimicrobial membrane, consistent with the view that the pathogen remodels host-microbe interface by co-opting the host autophagy machinery. Furthermore, we show that the host-pathogen interface is a hotspot for autophagosome biogenesis. Notably, overexpression of the early autophagosome biogenesis protein ATG9 enhances plant immunity. Our results implicate selective autophagy in polarized immune responses of plants and point to more complex functions for autophagy than the widely known degradative roles.
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Affiliation(s)
- Yasin F Dagdas
- The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom.,The Gregor Mendel Institute of Molecular Plant Biology, Vienna Biocenter, Vienna, Austria
| | - Pooja Pandey
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Yasin Tumtas
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | | | - Khaoula Belhaj
- The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Cian Duggan
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Alexandre Y Leary
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Maria E Segretin
- INGEBI-CONICET, Ciudad Autonoma de Buenos Aires, Buenos Aires, Argentina
| | - Mauricio P Contreras
- Department of Life Sciences, Imperial College London, London, United Kingdom.,INGEBI-CONICET, Ciudad Autonoma de Buenos Aires, Buenos Aires, Argentina
| | - Zachary Savage
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | | | - Sophien Kamoun
- The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Tolga O Bozkurt
- Department of Life Sciences, Imperial College London, London, United Kingdom
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156
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Dagdas YF, Pandey P, Tumtas Y, Sanguankiattichai N, Belhaj K, Duggan C, Leary AY, Segretin ME, Contreras MP, Savage Z, Khandare VS, Kamoun S, Bozkurt TO. Host autophagy machinery is diverted to the pathogen interface to mediate focal defense responses against the Irish potato famine pathogen. eLife 2018; 7:37476. [PMID: 29932422 DOI: 10.7554/elife.37476.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 06/21/2018] [Indexed: 05/27/2023] Open
Abstract
During plant cell invasion, the oomycete Phytophthora infestans remains enveloped by host-derived membranes whose functional properties are poorly understood. P. infestans secretes a myriad of effector proteins through these interfaces for plant colonization. Recently we showed that the effector protein PexRD54 reprograms host-selective autophagy by antagonising antimicrobial-autophagy receptor Joka2/NBR1 for ATG8CL binding (Dagdas et al., 2016). Here, we show that during infection, ATG8CL/Joka2 labelled defense-related autophagosomes are diverted toward the perimicrobial host membrane to restrict pathogen growth. PexRD54 also localizes to autophagosomes across the perimicrobial membrane, consistent with the view that the pathogen remodels host-microbe interface by co-opting the host autophagy machinery. Furthermore, we show that the host-pathogen interface is a hotspot for autophagosome biogenesis. Notably, overexpression of the early autophagosome biogenesis protein ATG9 enhances plant immunity. Our results implicate selective autophagy in polarized immune responses of plants and point to more complex functions for autophagy than the widely known degradative roles.
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Affiliation(s)
- Yasin F Dagdas
- The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
- The Gregor Mendel Institute of Molecular Plant Biology, Vienna Biocenter, Vienna, Austria
| | - Pooja Pandey
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Yasin Tumtas
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | | | - Khaoula Belhaj
- The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Cian Duggan
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Alexandre Y Leary
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Maria E Segretin
- INGEBI-CONICET, Ciudad Autonoma de Buenos Aires, Buenos Aires, Argentina
| | - Mauricio P Contreras
- Department of Life Sciences, Imperial College London, London, United Kingdom
- INGEBI-CONICET, Ciudad Autonoma de Buenos Aires, Buenos Aires, Argentina
| | - Zachary Savage
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | | | - Sophien Kamoun
- The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Tolga O Bozkurt
- Department of Life Sciences, Imperial College London, London, United Kingdom
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157
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Mamun MAA, Tang C, Sun Y, Islam MN, Liu P, Wang X, Kang Z. Wheat Gene TaATG8j Contributes to Stripe Rust Resistance. Int J Mol Sci 2018; 19:ijms19061666. [PMID: 29874811 PMCID: PMC6032272 DOI: 10.3390/ijms19061666] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2018] [Revised: 05/30/2018] [Accepted: 06/01/2018] [Indexed: 11/16/2022] Open
Abstract
Autophagy-related 8 (ATG8) protein has been reported to be involved in plant’s innate immune response, but it is not clear whether such genes play a similar role in cereal crops against obligate biotrophic fungal pathogens. Here, we reported an ATG8 gene from wheat (Triticum aestivum), designated TaATG8j. This gene has three copies located in chromosomes 2AS, 2BS, and 2DS. The transcriptions of all three copies were upregulated in plants of the wheat cultivar Suwon 11, inoculated with an avirulent race (CYR23) of Puccinia striiformis f. sp. tritici (Pst), the causal fungal pathogen of stripe rust. The transient expression of TaATG8j in Nicotiana benthamiana showed that TaATG8j proteins were distributed throughout the cytoplasm, but mainly in the nucleus and plasma membrane. The overexpression of TaATG8j in N. benthamiana slightly delayed the cell death caused by the mouse apoptotic protein BAX (BCL2-associated X protein). However, the expression of TaATG8j in yeast (Schizosaccharomyces pombe) induced cell death. The virus-induced gene silencing of all TaATG8j copies rendered Suwon 11 susceptible to the avirulent Pst race CYR23, accompanied by an increased fungal biomass and a decreased necrotic area per infection site. These results indicate that TaATG8j contributes to wheat resistance against stripe rust fungus by regulating cell death, providing information for the understanding of the mechanisms of wheat resistance to the stripe rust pathogen.
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Affiliation(s)
- Md Abdullah-Al Mamun
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling 712100, China.
- Regional Wheat Research Centre, Bangladesh Agricultural Research Institute, Shyampur, Rajshahi-6212, Bangladesh.
| | - Chunlei Tang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling 712100, China.
| | - Yingchao Sun
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling 712100, China.
| | - Md Nazrul Islam
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling 712100, China.
- Key Laboratory of Integrated Pest Management on the Loess Plateau of Ministry of Agriculture, Northwest A&F University, Yangling 712100, China.
- Agrochemical and Environmental Research Division, Institute of Food and Radiation Biology, Atomic Energy Research Establishment, Bangladesh Atomic Energy Commission, Ganakbari, Savar, Dhaka-1349, Bangladesh.
| | - Peng Liu
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling 712100, China.
| | - Xiaojie Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling 712100, China.
| | - Zhensheng Kang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling 712100, China.
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158
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Zeng H, Xie Y, Liu G, Lin D, He C, Shi H. Molecular identification of GAPDHs in cassava highlights the antagonism of MeGAPCs and MeATG8s in plant disease resistance against cassava bacterial blight. PLANT MOLECULAR BIOLOGY 2018; 97:201-214. [PMID: 29679263 DOI: 10.1007/s11103-018-0733-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 04/18/2018] [Indexed: 05/02/2023]
Abstract
KEY MESSAGE MeGAPCs were identified as negative regulators of plant disease resistance, and the interaction of MeGAPCs and MeATG8s was highlighted in plant defense response. As an important enzyme of glycolysis metabolic pathway, glyceraldehyde-3-P dehydrogenase (GAPDH) plays important roles in plant development, abiotic stress and immune responses. Cassava (Manihot esculenta) is most important tropical crop and one of the major food crops, however, no information is available about GAPDH gene family in cassava. In this study, 14 MeGAPDHs including 6 cytosol GAPDHs (MeGAPCs) were identified from cassava, and the transcripts of 14 MeGAPDHs in response to Xanthomonas axonopodis pv manihotis (Xam) indicated their possible involvement in immune responses. Further investigation showed that MeGAPCs are negative regulators of disease resistance against Xam. Through transient expression in Nicotiana benthamiana, we found that overexpression of MeGAPCs led to decreased disease resistance against Xam. On the contrary, MeGAPCs-silenced cassava plants through virus-induced gene silencing (VIGS) conferred improved disease resistance. Notably, MeGAPCs physically interacted with autophagy-related protein 8b (MeATG8b) and MeATG8e and inhibited autophagic activity. Moreover, MeATG8b and MeATG8e negatively regulated the activities of NAD-dependent MeGAPDHs, and are involved in MeGAPCs-mediated disease resistance. Taken together, this study highlights the involvement of MeGAPCs in plant disease resistance, through interacting with MeATG8b and MeATG8e.
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Affiliation(s)
- Hongqiu Zeng
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources, Institute of Tropical Agriculture and Forestry, Hainan University, Haikou, 570228, China
| | - Yanwei Xie
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources, Institute of Tropical Agriculture and Forestry, Hainan University, Haikou, 570228, China
| | - Guoyin Liu
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources, Institute of Tropical Agriculture and Forestry, Hainan University, Haikou, 570228, China
| | - Daozhe Lin
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources, Institute of Tropical Agriculture and Forestry, Hainan University, Haikou, 570228, China
| | - Chaozu He
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources, Institute of Tropical Agriculture and Forestry, Hainan University, Haikou, 570228, China
| | - Haitao Shi
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources, Institute of Tropical Agriculture and Forestry, Hainan University, Haikou, 570228, China.
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159
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Abstract
Plants have evolved sophisticated mechanisms to recycle intracellular constituents, which are essential for developmental and metabolic transitions; for efficient nutrient reuse; and for the proper disposal of proteins, protein complexes, and even entire organelles that become obsolete or dysfunctional. One major route is autophagy, which employs specialized vesicles to encapsulate and deliver cytoplasmic material to the vacuole for breakdown. In the past decade, the mechanics of autophagy and the scores of components involved in autophagic vesicle assembly have been documented. Now emerging is the importance of dedicated receptors that help recruit appropriate cargo, which in many cases exploit ubiquitylation as a signal. Although operating at a low constitutive level in all plant cells, autophagy is upregulated during senescence and various environmental challenges and is essential for proper nutrient allocation. Its importance to plant metabolism and energy balance in particular places autophagy at the nexus of robust crop performance, especially under suboptimal conditions.
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Affiliation(s)
| | - Richard D Vierstra
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri 63130, USA;
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160
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Pooggin MM, Ryabova LA. Ribosome Shunting, Polycistronic Translation, and Evasion of Antiviral Defenses in Plant Pararetroviruses and Beyond. Front Microbiol 2018; 9:644. [PMID: 29692761 PMCID: PMC5902531 DOI: 10.3389/fmicb.2018.00644] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 03/19/2018] [Indexed: 12/15/2022] Open
Abstract
Viruses have compact genomes and usually translate more than one protein from polycistronic RNAs using leaky scanning, frameshifting, stop codon suppression or reinitiation mechanisms. Viral (pre-)genomic RNAs often contain long 5′-leader sequences with short upstream open reading frames (uORFs) and secondary structure elements, which control both translation initiation and replication. In plants, viral RNA and DNA are targeted by RNA interference (RNAi) generating small RNAs that silence viral gene expression, while viral proteins are recognized by innate immunity and autophagy that restrict viral infection. In this review we focus on plant pararetroviruses of the family Caulimoviridae and describe the mechanisms of uORF- and secondary structure-driven ribosome shunting, leaky scanning and reinitiation after translation of short and long uORFs. We discuss conservation of these mechanisms in different genera of Caulimoviridae, including host genome-integrated endogenous viral elements, as well as in other viral families, and highlight a multipurpose use of the highly-structured leader sequence of plant pararetroviruses in regulation of translation, splicing, packaging, and reverse transcription of pregenomic RNA (pgRNA), and in evasion of RNAi. Furthermore, we illustrate how targeting of several host factors by a pararetroviral effector protein can lead to transactivation of viral polycistronic translation and concomitant suppression of antiviral defenses. Thus, activation of the plant protein kinase target of rapamycin (TOR) by the Cauliflower mosaic virus transactivator/viroplasmin (TAV) promotes reinitiation of translation after long ORFs on viral pgRNA and blocks antiviral autophagy and innate immunity responses, while interaction of TAV with the plant RNAi machinery interferes with antiviral silencing.
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Affiliation(s)
- Mikhail M Pooggin
- INRA, UMR Biologie et Génétique des Interactions Plante-Parasite, Montpellier, France
| | - Lyubov A Ryabova
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, UPR 2357, Université de Strasbourg, Strasbourg, France
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161
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Zhou S, Hong Q, Li Y, Li Q, Wang M. Autophagy contributes to regulate the ROS levels and PCD progress in TMV-infected tomatoes. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2018; 269:12-19. [PMID: 29606209 DOI: 10.1016/j.plantsci.2017.11.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 10/10/2017] [Accepted: 11/01/2017] [Indexed: 06/08/2023]
Abstract
Programmed cell death (PCD) and autophagy are both important means for plants to resist pathogen. It is also the main biological reaction of plant immunity. In previous studies, we found that TMV local-infection on tomato leaves not only caused the PCD process in the distal root tissues, but also induced autophagy in root-tip cells. However, the reasons for these biological phenomena are unclear. In order to get deeper insight, the role of a putative inducible factor reactive oxidative species (ROS) was investigated. The situ staining and subcellular localization analysis showed that the ROS level in the root tissue of TMV infected plants was significantly promoted. TEM observation showed that the intracellular ROS was excreted into the cell wall and intercellular layer. At the same time, the results of western blot and qRT-PCR showed that the expression of autophagy related protein Atg8 and genes (Atg5, Atg7 and Atg10) were increased. However, in the subsequent DPI inhibition experiments we found that the accumulation of ROS in infected plant root-tip tissues was inhibited and the autophagy in the root-tip cells also decreased. When 3-methyladenine (3-MA) was used to inhibit autophagy, there was no significant change in the ROS level in the apical tissue, while the systemic PCD process of the root-tip cells was elevated. Taken together, these results indicate that local TMV inoculation on the leaves induced the root-tip cells producing and releasing a lot of ROS into the extracellular matrix for defense against pathogen invasion. Meanwhile, ROS acted as a signaling substance and triggered autophagy in root-tip cells, in order to eliminate excessive intracellular ROS oxidative damage and maintain cell survival.
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Affiliation(s)
- Shumin Zhou
- Lab of Plant Cell Biology, Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Qiang Hong
- Lab of Plant Cell Biology, Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Yang Li
- Lab of Plant Cell Biology, Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Qi Li
- Lab of Plant Cell Biology, Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Mao Wang
- College of Biology, China Agricultural University, Beijing 100094, China.
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162
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Li F, Zhang C, Li Y, Wu G, Hou X, Zhou X, Wang A. Beclin1 restricts RNA virus infection in plants through suppression and degradation of the viral polymerase. Nat Commun 2018; 9:1268. [PMID: 29593293 PMCID: PMC5871769 DOI: 10.1038/s41467-018-03658-2] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Accepted: 02/28/2018] [Indexed: 01/22/2023] Open
Abstract
Autophagy emerges as an essential immunity defense against intracellular pathogens. Here we report that turnip mosaic virus (TuMV) infection activates autophagy in plants and that Beclin1 (ATG6), a core component of autophagy, inhibits virus replication. Beclin1 interacts with NIb, the RNA-dependent RNA polymerase (RdRp) of TuMV, via the highly conserved GDD motif and the interaction complex is targeted for autophagic degradation likely through the adaptor protein ATG8a. Beclin1-mediated NIb degradation is inhibited by autophagy inhibitors. Deficiency of Beclin1 or ATG8a enhances NIb accumulation and promotes viral infection and vice versa. These data suggest that Beclin1 may be a selective autophagy receptor. Overexpression of a Beclin1 truncation mutant that binds to NIb but lacks the ability to mediate NIb degradation also inhibits virus replication. The Beclin1-RdRp interaction further extends to several RNA viruses. Thus Beclin1 restricts viral infection through suppression and also likely autophagic degradation of the viral RdRp.
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Affiliation(s)
- Fangfang Li
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, ON, N5V 4T3, Canada
- Department of Biology, Western University, London, ON, N6A 5B7, Canada
| | - Changwei Zhang
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, ON, N5V 4T3, Canada
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 210095, Nanjing, China
| | - Yinzi Li
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, ON, N5V 4T3, Canada
- Department of Biology, Western University, London, ON, N6A 5B7, Canada
| | - Guanwei Wu
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, ON, N5V 4T3, Canada
- Department of Biology, Western University, London, ON, N6A 5B7, Canada
| | - Xilin Hou
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 210095, Nanjing, China
| | - Xueping Zhou
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, 100193, Beijing, China
| | - Aiming Wang
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, ON, N5V 4T3, Canada.
- Department of Biology, Western University, London, ON, N6A 5B7, Canada.
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163
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Leary AY, Sanguankiattichai N, Duggan C, Tumtas Y, Pandey P, Segretin ME, Salguero Linares J, Savage ZD, Yow RJ, Bozkurt TO. Modulation of plant autophagy during pathogen attack. JOURNAL OF EXPERIMENTAL BOTANY 2018; 69:1325-1333. [PMID: 29294077 DOI: 10.1093/jxb/erx425] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In plants, the highly conserved catabolic process of autophagy has long been known as a means of maintaining cellular homeostasis and coping with abiotic stress conditions. Accumulating evidence has linked autophagy to immunity against invading pathogens, regulating plant cell death, and antimicrobial defences. In turn, it appears that phytopathogens have evolved ways not only to evade autophagic clearance but also to modulate and co-opt autophagy for their own benefit. In this review, we summarize and discuss the emerging discoveries concerning how pathogens modulate both host and self-autophagy machineries to colonize their host plants, delving into the arms race that determines the fate of interorganismal interaction.
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164
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Avin-Wittenberg T, Baluška F, Bozhkov PV, Elander PH, Fernie AR, Galili G, Hassan A, Hofius D, Isono E, Le Bars R, Masclaux-Daubresse C, Minina EA, Peled-Zehavi H, Coll NS, Sandalio LM, Satiat-Jeunemaitre B, Sirko A, Testillano PS, Batoko H. Autophagy-related approaches for improving nutrient use efficiency and crop yield protection. JOURNAL OF EXPERIMENTAL BOTANY 2018; 69:1335-1353. [PMID: 29474677 DOI: 10.1093/jxb/ery069] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Accepted: 02/16/2018] [Indexed: 05/18/2023]
Abstract
Autophagy is a eukaryotic catabolic pathway essential for growth and development. In plants, it is activated in response to environmental cues or developmental stimuli. However, in contrast to other eukaryotic systems, we know relatively little regarding the molecular players involved in autophagy and the regulation of this complex pathway. In the framework of the COST (European Cooperation in Science and Technology) action TRANSAUTOPHAGY (2016-2020), we decided to review our current knowledge of autophagy responses in higher plants, with emphasis on knowledge gaps. We also assess here the potential of translating the acquired knowledge to improve crop plant growth and development in a context of growing social and environmental challenges for agriculture in the near future.
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Affiliation(s)
- Tamar Avin-Wittenberg
- Department of Plant and Environmental Sciences, Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Givat Ram, Jerusalem, Israel
| | - Frantisek Baluška
- Institute of Cellular and Molecular Botany, University of Bonn, Kirschallee, Bonn, Germany
| | - Peter V Bozhkov
- Department of Molecular Sciences, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, Uppsala, Sweden
| | - Pernilla H Elander
- Department of Molecular Sciences, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, Uppsala, Sweden
| | - Alisdair R Fernie
- Max-Planck-Institute of Molecular Plant Physiology, Am Mühlenberg, Potsdam-Golm, Germany
| | - Gad Galili
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot Israel
| | - Ammar Hassan
- Institute of Cellular and Molecular Botany, University of Bonn, Kirschallee, Bonn, Germany
| | - Daniel Hofius
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center of Plant Biology, Uppsala, Sweden
| | - Erika Isono
- Department of Biology, University of Konstanz, Universitätsstrasse, Konstanz, Germany
| | - Romain Le Bars
- Cell Biology Pôle Imagerie-Gif, Institute of Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Céline Masclaux-Daubresse
- INRA-AgroParisTech, Institut Jean-Pierre Bourgin, UMR1318, ERL CNRS 3559, Saclay Plant Sciences, Versailles, France
| | - Elena A Minina
- Department of Molecular Sciences, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, Uppsala, Sweden
| | - Hadas Peled-Zehavi
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot Israel
| | - Núria S Coll
- Centre for Research in Agricultural Genomics (CSIC-IRTA-UAB-UB), Bellaterra-Cerdanyola del Valles, Catalonia, Spain
| | - Luisa M Sandalio
- Departmento de Bioquímica, Biología Celular y Molecular de Plantas Experimental del Zaidín, CSIC, Granada, Spain
| | - Béatrice Satiat-Jeunemaitre
- Cell Biology Pôle Imagerie-Gif, Institute of Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Agnieszka Sirko
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, ul. Pawinskiego, Warsaw, Poland
| | - Pilar S Testillano
- Pollen Biotechnology of Crop Plants group, Centro de Investigaciones Biológicas, Biological Research Centre (CIB), CSIC, Ramiro de Maeztu, Madrid, Spain
| | - Henri Batoko
- Université Catholique de Louvain, Institute of Life Sciences, Croix du Sud, Louvain-la-Neuve, Belgium
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165
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Affiliation(s)
- Peter V Bozhkov
- Department of Molecular Sciences, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, Uppsala, Sweden
- Correspondence:
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166
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Üstün S, Hafrén A, Liu Q, Marshall RS, Minina EA, Bozhkov PV, Vierstra RD, Hofius D. Bacteria Exploit Autophagy for Proteasome Degradation and Enhanced Virulence in Plants. THE PLANT CELL 2018; 30:668-685. [PMID: 29500318 PMCID: PMC5894834 DOI: 10.1105/tpc.17.00815] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 02/09/2018] [Accepted: 03/01/2018] [Indexed: 05/21/2023]
Abstract
Autophagy and the ubiquitin-proteasome system (UPS) are two major protein degradation pathways implicated in the response to microbial infections in eukaryotes. In animals, the contribution of autophagy and the UPS to antibacterial immunity is well documented and several bacteria have evolved measures to target and exploit these systems to the benefit of infection. In plants, the UPS has been established as a hub for immune responses and is targeted by bacteria to enhance virulence. However, the role of autophagy during plant-bacterial interactions is less understood. Here, we have identified both pro- and antibacterial functions of autophagy mechanisms upon infection of Arabidopsis thaliana with virulent Pseudomonas syringae pv tomato DC3000 (Pst). We show that Pst activates autophagy in a type III effector (T3E)-dependent manner and stimulates the autophagic removal of proteasomes (proteaphagy) to support bacterial proliferation. We further identify the T3E Hrp outer protein M1 (HopM1) as a principle mediator of autophagy-inducing activities during infection. In contrast to the probacterial effects of Pst-induced proteaphagy, NEIGHBOR OF BRCA1-dependent selective autophagy counteracts disease progression and limits the formation of HopM1-mediated water-soaked lesions. Together, we demonstrate that distinct autophagy pathways contribute to host immunity and bacterial pathogenesis during Pst infection and provide evidence for an intimate crosstalk between proteasome and autophagy in plant-bacterial interactions.
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Affiliation(s)
- Suayib Üstün
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, 75007 Uppsala, Sweden
| | - Anders Hafrén
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, 75007 Uppsala, Sweden
| | - Qinsong Liu
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, 75007 Uppsala, Sweden
| | - Richard S Marshall
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri 63130
| | - Elena A Minina
- Department of Molecular Sciences, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, 75007 Uppsala, Sweden
| | - Peter V Bozhkov
- Department of Molecular Sciences, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, 75007 Uppsala, Sweden
| | - Richard D Vierstra
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri 63130
| | - Daniel Hofius
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, 75007 Uppsala, Sweden
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167
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Romero-Barrios N, Vert G. Proteasome-independent functions of lysine-63 polyubiquitination in plants. THE NEW PHYTOLOGIST 2018; 217:995-1011. [PMID: 29194634 DOI: 10.1111/nph.14915] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 10/12/2017] [Indexed: 05/21/2023]
Abstract
Contents Summary 995 I. Introduction 995 II. The plant Ub machinery 996 III. From Ub to Ub linkage types in plants 997 IV. Increasing analytical resolution for K63 polyUb in plants 998 V. How to build K63 polyUb chains? 998 VI. Cellular roles of K63 polyUb in plants 999 VII. Physiological roles of K63 polyUb in plants 1004 VIII. Future perspectives: towards the next level of the Ub code 1006 Acknowledgements 1006 References 1007 SUMMARY: Ubiquitination is a post-translational modification essential for the regulation of eukaryotic proteins, having an impact on protein fate, function, localization or activity. What originally appeared to be a simple system to regulate protein turnover by the 26S proteasome is now known to be the most intricate regulatory process cells have evolved. Ubiquitin can be arranged in countless chain assemblies, triggering various cellular outcomes. Polyubiquitin chains using lysine-63 from ubiquitin represent the second most abundant type of ubiquitin modification. Recent studies have exposed their common function in proteasome-independent functions in non-plant model organisms. The existence of lysine-63 polyubiquitination in plants is, however, only just emerging. In this review, we discuss the recent advances on the characterization of ubiquitin chains and the molecular mechanisms driving the formation of lysine-63-linked ubiquitin modifications. We provide an overview of the roles associated with lysine-63 polyubiquitination in plant cells in the light of what is known in non-plant models. Finally, we review the crucial roles of lysine-63 polyubiquitin-dependent processes in plant growth, development and responses to environmental conditions.
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Affiliation(s)
- Natali Romero-Barrios
- Institute for Integrative Biology of the Cell (I2BC), CNRS/CEA/Univ. Paris Sud, Université Paris-Saclay, Gif-sur-Yvette, 91198, France
| | - Grégory Vert
- Institute for Integrative Biology of the Cell (I2BC), CNRS/CEA/Univ. Paris Sud, Université Paris-Saclay, Gif-sur-Yvette, 91198, France
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168
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Soto-Burgos J, Zhuang X, Jiang L, Bassham DC. Dynamics of Autophagosome Formation. PLANT PHYSIOLOGY 2018; 176:219-229. [PMID: 29061903 PMCID: PMC5761814 DOI: 10.1104/pp.17.01236] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 10/18/2017] [Indexed: 05/20/2023]
Abstract
Environmental stress activates autophagy and leads to autophagosome formation at the endoplasmic reticulum.
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Affiliation(s)
- Junmarie Soto-Burgos
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, Iowa 50011
| | - Xiaohong Zhuang
- Centre for Cell and Developmental Biology, State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Liwen Jiang
- Centre for Cell and Developmental Biology, State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Diane C Bassham
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, Iowa 50011
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169
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Hafrén A, Üstün S, Hochmuth A, Svenning S, Johansen T, Hofius D. Turnip Mosaic Virus Counteracts Selective Autophagy of the Viral Silencing Suppressor HCpro. PLANT PHYSIOLOGY 2018; 176:649-662. [PMID: 29133371 PMCID: PMC5761789 DOI: 10.1104/pp.17.01198] [Citation(s) in RCA: 113] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Accepted: 11/10/2017] [Indexed: 05/19/2023]
Abstract
Autophagy is a conserved intracellular degradation pathway and has emerged as a key mechanism of antiviral immunity in metazoans, including the selective elimination of viral components. In turn, some animal viruses are able to escape and modulate autophagy for enhanced pathogenicity. Whether host autophagic responses and viral countermeasures play similar roles in plant-virus interactions is not well understood. Here, we have identified selective autophagy as antiviral pathway during plant infection with turnip mosaic virus (TuMV), a positive-stranded RNA potyvirus. We show that the autophagy cargo receptor NBR1 suppresses viral accumulation by targeting the viral RNA silencing suppressor helper-component proteinase (HCpro), presumably in association with virus-induced RNA granules. Intriguingly, TuMV seems to antagonize NBR1-dependent autophagy during infection by the activity of distinct viral proteins, thereby limiting its antiviral capacity. We also found that NBR1-independent bulk autophagy prevents premature plant death, thus extending the lifespan of virus reservoirs and particle production. Together, our study highlights a conserved role of selective autophagy in antiviral immunity and suggests the evolvement of viral protein functions to inhibit autophagy processes, despite a potential trade-off in host survival.
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Affiliation(s)
- Anders Hafrén
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences (SLU) and Linnean Center for Plant Biology, 75007 Uppsala, Sweden
| | - Suayib Üstün
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences (SLU) and Linnean Center for Plant Biology, 75007 Uppsala, Sweden
| | - Anton Hochmuth
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences (SLU) and Linnean Center for Plant Biology, 75007 Uppsala, Sweden
| | - Steingrim Svenning
- Molecular Cancer Research Group, Institute of Medical Biology, University of Tromsø - The Arctic University of Norway, 9037 Tromsø, Norway
| | - Terje Johansen
- Molecular Cancer Research Group, Institute of Medical Biology, University of Tromsø - The Arctic University of Norway, 9037 Tromsø, Norway
| | - Daniel Hofius
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences (SLU) and Linnean Center for Plant Biology, 75007 Uppsala, Sweden
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170
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Pecenková T, Markovic V, Sabol P, Kulich I, Žárský V. Exocyst and autophagy-related membrane trafficking in plants. JOURNAL OF EXPERIMENTAL BOTANY 2017; 69:47-57. [PMID: 29069430 DOI: 10.1093/jxb/erx363] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Endomembrane traffic in eukaryotic cells functions partially as a means of communication; delivery of membrane in one direction has to be balanced with a reduction at the other end. This effect is typically the case during the defence against pathogens. To combat pathogens, cellular growth and differentiation are suppressed, while endomembrane traffic is poised towards limiting the pathogen attack. The octameric exocyst vesicle-tethering complex was originally discovered as a factor facilitating vesicle-targeting and vesicle-plasma membrane (PM) fusion during exocytosis prior to and possibly during SNARE complex formation. Interestingly, it was recently implicated both in animals and plants in autophagy membrane traffic. In animal cells, the exocyst is integrated into the mTOR-regulated energy metabolism stress/starvation pathway, participating in the formation and especially initiation of an autophagosome. In plants, the first functional link was to autophagy-related anthocyanin import to the vacuole and to starvation. In this concise review, we summarize the current knowledge of exocyst functions in autophagy and defence in plants that might involve unconventional secretion and compare it with animal conditions. Formation of different exocyst complexes during undisturbed cell growth, as opposed to periods of cellular stress reactions involving autophagy, might contribute to the coordination of endomembrane trafficking pathways.
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Affiliation(s)
- Tamara Pecenková
- Laboratory of Cell Biology, Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Czech Republic
- Laboratory of Cell Morphogenesis, Department of Experimental Plant Biology, Charles University in Prague, Faculty of Science, Czech Republic
| | - Vedrana Markovic
- Laboratory of Cell Biology, Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Czech Republic
- Laboratory of Cell Morphogenesis, Department of Experimental Plant Biology, Charles University in Prague, Faculty of Science, Czech Republic
| | - Peter Sabol
- Laboratory of Cell Morphogenesis, Department of Experimental Plant Biology, Charles University in Prague, Faculty of Science, Czech Republic
| | - Ivan Kulich
- Laboratory of Cell Morphogenesis, Department of Experimental Plant Biology, Charles University in Prague, Faculty of Science, Czech Republic
| | - Viktor Žárský
- Laboratory of Cell Biology, Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Czech Republic
- Laboratory of Cell Morphogenesis, Department of Experimental Plant Biology, Charles University in Prague, Faculty of Science, Czech Republic
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171
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Geldreich A, Haas G, Kubina J, Bouton C, Tanguy M, Erhardt M, Keller M, Ryabova L, Dimitrova M. Formation of large viroplasms and virulence of Cauliflower mosaic virus in turnip plants depend on the N-terminal EKI sequence of viral protein TAV. PLoS One 2017; 12:e0189062. [PMID: 29253877 PMCID: PMC5734791 DOI: 10.1371/journal.pone.0189062] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 11/17/2017] [Indexed: 12/11/2022] Open
Abstract
Cauliflower mosaic virus (CaMV) TAV protein (TransActivator/Viroplasmin) plays a pivotal role during the infection cycle since it activates translation reinitiation of viral polycistronic RNAs and suppresses RNA silencing. It is also the major component of cytoplasmic electron-dense inclusion bodies (EDIBs) called viroplasms that are particularly evident in cells infected by the virulent CaMV Cabb B-JI isolate. These EDIBs are considered as virion factories, vehicles for CaMV intracellular movement and reservoirs for CaMV transmission by aphids. In this study, focused on different TAV mutants in vivo, we demonstrate that three physically separated domains collectively participate to the formation of large EDIBs: the N-terminal EKI motif, a sequence of the MAV domain involved in translation reinitiation and a C-terminal region encompassing the zinc finger. Surprisingly, EKI mutant TAVm3, corresponding to a substitution of the EKI motif at amino acids 11-13 by three alanines (AAA), which completely abolished the formation of large viroplasms, was not lethal for CaMV but highly reduced its virulence without affecting the rate of systemic infection. Expression of TAVm3 in a viral context led to formation of small irregularly shaped inclusion bodies, mild symptoms and low levels of viral DNA and particles accumulation, despite the production of significant amounts of mature capsid proteins. Unexpectedly, for CaMV-TAVm3 the formation of viral P2-containing electron-light inclusion body (ELIB), which is essential for CaMV aphid transmission, was also altered, thus suggesting an indirect role of the EKI tripeptide in CaMV plant-to-plant propagation. This important functional contribution of the EKI motif in CaMV biology can explain the strict conservation of this motif in the TAV sequences of all CaMV isolates.
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Affiliation(s)
- Angèle Geldreich
- Institut de Biologie Moléculaire des Plantes, CNRS UPR2357, Université de Strasbourg, Strasbourg, France
| | - Gabrielle Haas
- Institut de Biologie Moléculaire des Plantes, CNRS UPR2357, Université de Strasbourg, Strasbourg, France
| | - Julie Kubina
- Institut de Biologie Moléculaire des Plantes, CNRS UPR2357, Université de Strasbourg, Strasbourg, France
| | - Clément Bouton
- Institut de Biologie Moléculaire des Plantes, CNRS UPR2357, Université de Strasbourg, Strasbourg, France
| | - Mélanie Tanguy
- Institut de Biologie Moléculaire des Plantes, CNRS UPR2357, Université de Strasbourg, Strasbourg, France
| | - Mathieu Erhardt
- Institut de Biologie Moléculaire des Plantes, CNRS UPR2357, Université de Strasbourg, Strasbourg, France
| | - Mario Keller
- Institut de Biologie Moléculaire des Plantes, CNRS UPR2357, Université de Strasbourg, Strasbourg, France
| | - Lyubov Ryabova
- Institut de Biologie Moléculaire des Plantes, CNRS UPR2357, Université de Strasbourg, Strasbourg, France
| | - Maria Dimitrova
- Institut de Biologie Moléculaire des Plantes, CNRS UPR2357, Université de Strasbourg, Strasbourg, France
- * E-mail:
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172
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Batoko H, Dagdas Y, Baluska F, Sirko A. Understanding and exploiting autophagy signaling in plants. Essays Biochem 2017; 61:675-685. [PMID: 29233877 PMCID: PMC5869243 DOI: 10.1042/ebc20170034] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 10/11/2017] [Accepted: 10/19/2017] [Indexed: 12/20/2022]
Abstract
Autophagy is an essential catabolic pathway and is activated by various endogenous and exogenous stimuli. In particular, autophagy is required to allow sessile organisms such as plants to cope with biotic or abiotic stress conditions. It is thought that these various environmental signaling pathways are somehow integrated with autophagy signaling. However, the molecular mechanisms of plant autophagy signaling are not well understood, leaving a big gap of knowledge as a barrier to being able to manipulate this important pathway to improve plant growth and development. In this review, we discuss possible regulatory mechanisms at the core of plant autophagy signaling.
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Affiliation(s)
- Henri Batoko
- Université catholique de Louvain, Institut des Sciences de la Vie, Croix du Sud 4, L7.07.14, 1348 Louvain-la-Neuve, Belgium
| | - Yasin Dagdas
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna Biocenter, Dr. Bohr-Gasse 3, 1030 Vienna, Austria
| | | | - Agnieszka Sirko
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, Pawinskiego 5A, 02-106 Warsaw, Poland
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173
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Üstün S, Hafrén A, Hofius D. Autophagy as a mediator of life and death in plants. CURRENT OPINION IN PLANT BIOLOGY 2017; 40:122-130. [PMID: 28946008 DOI: 10.1016/j.pbi.2017.08.011] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 08/14/2017] [Accepted: 08/16/2017] [Indexed: 05/20/2023]
Abstract
Autophagy is a major pathway for degradation and recycling of cytoplasmic material, including individual proteins, aggregates, and entire organelles. Autophagic processes serve mainly survival functions in cellular homeostasis, stress adaptation and immune responses but can also have death-promoting activities in different eukaryotic organisms. In plants, the role of autophagy in the regulation of programmed cell death (PCD) remained elusive and a subject of debate. More recent evidence, however, has resulted in the consensus that autophagy can either promote or restrict different forms of PCD. Here, we present latest advances in understanding the molecular mechanisms and functions of plant autophagy and discuss their implications for life and death decisions in the context of developmental and pathogen-induced PCD.
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Affiliation(s)
- Suayib Üstün
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences (SLU) and Linnean Center for Plant Biology, SE-75007 Uppsala, Sweden
| | - Anders Hafrén
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences (SLU) and Linnean Center for Plant Biology, SE-75007 Uppsala, Sweden
| | - Daniel Hofius
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences (SLU) and Linnean Center for Plant Biology, SE-75007 Uppsala, Sweden.
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174
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Schoelz JE, Leisner S. Setting Up Shop: The Formation and Function of the Viral Factories of Cauliflower mosaic virus. FRONTIERS IN PLANT SCIENCE 2017; 8:1832. [PMID: 29163571 PMCID: PMC5670102 DOI: 10.3389/fpls.2017.01832] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Accepted: 10/10/2017] [Indexed: 05/23/2023]
Abstract
Similar to cells, viruses often compartmentalize specific functions such as genome replication or particle assembly. Viral compartments may contain host organelle membranes or they may be mainly composed of viral proteins. These compartments are often termed: inclusion bodies (IBs), viroplasms or viral factories. The same virus may form more than one type of IB, each with different functions, as illustrated by the plant pararetrovirus, Cauliflower mosaic virus (CaMV). CaMV forms two distinct types of IBs in infected plant cells, those composed mainly of the viral proteins P2 (which are responsible for transmission of CaMV by insect vectors) and P6 (required for viral intra-and inter-cellular infection), respectively. P6 IBs are the major focus of this review. Much of our understanding of the formation and function of P6 IBs comes from the analyses of their major protein component, P6. Over time, the interactions and functions of P6 have been gradually elucidated. Coupled with new technologies, such as fluorescence microscopy with fluorophore-tagged viral proteins, these data complement earlier work and provide a clearer picture of P6 IB formation. As the activities and interactions of the viral proteins have gradually been determined, the functions of P6 IBs have become clearer. This review integrates the current state of knowledge on the formation and function of P6 IBs to produce a coherent model for the activities mediated by these sophisticated virus-manufacturing machines.
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Affiliation(s)
- James E. Schoelz
- Division of Plant Sciences, University of Missouri, Columbia, MO, United States
| | - Scott Leisner
- Department of Biological Sciences, University of Toledo, Toledo, OH, United States
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175
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Czosnek H, Hariton-Shalev A, Sobol I, Gorovits R, Ghanim M. The Incredible Journey of Begomoviruses in Their Whitefly Vector. Viruses 2017; 9:E273. [PMID: 28946649 PMCID: PMC5691625 DOI: 10.3390/v9100273] [Citation(s) in RCA: 93] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 09/13/2017] [Accepted: 09/18/2017] [Indexed: 12/21/2022] Open
Abstract
Begomoviruses are vectored in a circulative persistent manner by the whitefly Bemisia tabaci. The insect ingests viral particles with its stylets. Virions pass along the food canal and reach the esophagus and the midgut. They cross the filter chamber and the midgut into the haemolymph, translocate into the primary salivary glands and are egested with the saliva into the plant phloem. Begomoviruses have to cross several barriers and checkpoints successfully, while interacting with would-be receptors and other whitefly proteins. The bulk of the virus remains associated with the midgut and the filter chamber. In these tissues, viral genomes, mainly from the tomato yellow leaf curl virus (TYLCV) family, may be transcribed and may replicate. However, at the same time, virus amounts peak, and the insect autophagic response is activated, which in turn inhibits replication and induces the destruction of the virus. Some begomoviruses invade tissues outside the circulative pathway, such as ovaries and fat cells. Autophagy limits the amounts of virus associated with these organs. In this review, we discuss the different sites begomoviruses need to cross to complete a successful circular infection, the role of the coat protein in this process and the sites that balance between virus accumulation and virus destruction.
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Affiliation(s)
- Henryk Czosnek
- Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, 7610001, Israel.
| | - Aliza Hariton-Shalev
- Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, 7610001, Israel.
| | - Iris Sobol
- Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, 7610001, Israel.
| | - Rena Gorovits
- Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, 7610001, Israel.
| | - Murad Ghanim
- Department of Entomology, Agricultural Research Organization, Volcani Center, HaMaccabim Road 68, Rishon LeZion, 7505101, Israel.
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176
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Clavel M, Michaeli S, Genschik P. Autophagy: A Double-Edged Sword to Fight Plant Viruses. TRENDS IN PLANT SCIENCE 2017; 22:646-648. [PMID: 28633985 DOI: 10.1016/j.tplants.2017.06.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 06/06/2017] [Accepted: 06/06/2017] [Indexed: 05/20/2023]
Abstract
In metazoans, autophagy is an essential component of host defense against viruses, orchestrating their degradation. Such antiviral functions for autophagy have also been long suspected in the green lineage. Two recent reports provide molecular insights on how plants selectively send viral proteins and even particles to the vacuole.
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Affiliation(s)
- Marion Clavel
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, Unité Propre de Recherche 2357, Conventionné avec l'Université de Strasbourg, 67084 Strasbourg, France
| | - Simon Michaeli
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, Unité Propre de Recherche 2357, Conventionné avec l'Université de Strasbourg, 67084 Strasbourg, France
| | - Pascal Genschik
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, Unité Propre de Recherche 2357, Conventionné avec l'Université de Strasbourg, 67084 Strasbourg, France.
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177
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New advances in autophagy in plants: Regulation, selectivity and function. Semin Cell Dev Biol 2017; 80:113-122. [PMID: 28734771 DOI: 10.1016/j.semcdb.2017.07.018] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 07/08/2017] [Accepted: 07/15/2017] [Indexed: 01/01/2023]
Abstract
Autophagy is a major and conserved pathway for delivering unwanted proteins or damaged organelles to the vacuole for degradation and recycling. In plants, it functions as a housekeeping process to maintain cellular homeostasis under normal conditions and is induced by stress and senescence; it thus plays important roles in development, stress tolerance and metabolism. Autophagy can both execute bulk degradation and be highly selective in targeting cargos under specific environmental conditions or during certain developmental processes. Here, we review recent research on autophagy in plants, and discuss new insights into its core mechanism, regulation, selectivity and physiological roles. Potential future directions are also highlighted.
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