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Kulich I, Vojtíková Z, Sabol P, Ortmannová J, Neděla V, Tihlaříková E, Žárský V. Exocyst Subunit EXO70H4 Has a Specific Role in Callose Synthase Secretion and Silica Accumulation. PLANT PHYSIOLOGY 2018; 176:2040-2051. [PMID: 29301954 PMCID: PMC5841730 DOI: 10.1104/pp.17.01693] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 01/02/2018] [Indexed: 05/20/2023]
Abstract
Biogenesis of the plant secondary cell wall involves many important aspects, such as phenolic compound deposition and often silica encrustation. Previously, we demonstrated the importance of the exocyst subunit EXO70H4 for biogenesis of the trichome secondary cell wall, namely for deposition of the autofluorescent and callose-rich cell wall layer. Here, we reveal that EXO70H4-driven cell wall biogenesis is constitutively active in the mature trichome, but also can be activated elsewhere upon pathogen attack, giving this study a broader significance with an overlap into phytopathology. To address the specificity of EXO70H4 among the EXO70 family, we complemented the exo70H4-1 mutant by 18 different Arabidopsis (Arabidopsis thaliana) EXO70 paralogs subcloned under the EXO70H4 promoter. Only EXO70H4 had the capacity to rescue the exo70H4-1 trichome phenotype. Callose deposition phenotype of exo70H4-1 mutant is caused by impaired secretion of PMR4, a callose synthase responsible for the synthesis of callose in the trichome. PMR4 colocalizes with EXO70H4 on plasma membrane microdomains that do not develop in the exo70H4-1 mutant. Using energy-dispersive x-ray microanalysis, we show that both EXO70H4- and PMR4-dependent callose deposition in the trichome are essential for cell wall silicification.
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Affiliation(s)
- Ivan Kulich
- Department of Experimental Plant Biology, Faculty of Sciences, Charles University, Prague, Czech Republic
| | - Zdeňka Vojtíková
- Department of Experimental Plant Biology, Faculty of Sciences, Charles University, Prague, Czech Republic
| | - Peter Sabol
- Department of Experimental Plant Biology, Faculty of Sciences, Charles University, Prague, Czech Republic
| | - Jitka Ortmannová
- Department of Experimental Plant Biology, Faculty of Sciences, Charles University, Prague, Czech Republic
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Vilém Neděla
- Institute of Scientific Instruments of the Academy of Sciences of the Czech Republic, Brno, Czech Republic
| | - Eva Tihlaříková
- Institute of Scientific Instruments of the Academy of Sciences of the Czech Republic, Brno, Czech Republic
| | - Viktor Žárský
- Department of Experimental Plant Biology, Faculty of Sciences, Charles University, Prague, Czech Republic
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Prague, Czech Republic
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52
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Ma J, Chen J, Wang M, Ren Y, Wang S, Lei C, Cheng Z. Disruption of OsSEC3A increases the content of salicylic acid and induces plant defense responses in rice. JOURNAL OF EXPERIMENTAL BOTANY 2018; 69:1051-1064. [PMID: 29300985 PMCID: PMC6018903 DOI: 10.1093/jxb/erx458] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 12/13/2017] [Indexed: 05/19/2023]
Abstract
The exocyst, an evolutionarily conserved octameric protein complex involved in exocytosis, has been reported to be involved in diverse aspects of morphogenesis in Arabidopsis. However, the molecular functions of such exocytotic molecules in rice are poorly understood. Here, we examined the molecular function of OsSEC3A, an important subunit of the exocyst complex in rice. The OsSEC3A gene is expressed in various organs, and OsSEC3A has the potential ability to participate in the exocyst complex by interacting with several other exocyst subunits. Disruption of OsSEC3A by CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9) caused dwarf stature and a lesion-mimic phenotype. The Ossec3a mutant exhibited enhanced defense responses, as shown by up-regulated transcript levels of pathogenesis- and salicylic acid synthesis-related genes, increased levels of salicylic acid, and enhanced resistance to the fungal pathogen Magnaporthe oryzae. Subcellular localization analysis demonstrated that OsSEC3A has a punctate distribution with the plasma membrane. In addition, OsSEC3A interacted with rice SNAP25-type t-SNARE protein OsSNAP32, which is involved in rice blast resistance, via the C-terminus and bound to phosphatidylinositol lipids, particularly phosphatidylinositol-3-phosphate, through its N-terminus. These findings uncover the novel function of rice exocyst subunit SEC3 in defense responses.
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Affiliation(s)
- Jin Ma
- Key Laboratory of Ministry of Education for Cell Proliferation and Differentiation, College of Life Sciences, Peking University, Beijing, China
| | - Jun Chen
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Min Wang
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Yulong Ren
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Shuai Wang
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Cailin Lei
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Zhijun Cheng
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing, China
- Correspondence: and
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53
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van Gisbergen PAC, Wu SZ, Chang M, Pattavina KA, Bartlett ME, Bezanilla M. An ancient Sec10-formin fusion provides insights into actin-mediated regulation of exocytosis. J Cell Biol 2018; 217:945-957. [PMID: 29374070 PMCID: PMC5839782 DOI: 10.1083/jcb.201705084] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 12/21/2017] [Accepted: 01/08/2018] [Indexed: 11/22/2022] Open
Abstract
Interactions between actin nucleators and the exocyst in yeast and mammals control membrane remodeling. van Gisbergen et al. now describe For1F, a fusion of an exocyst subunit (Sec10) and an actin nucleation factor (formin), retained in the moss lineage for more than 170 million years, which provides unique insight into the regulation of exocytosis by actin. Exocytosis, facilitated by the exocyst, is fundamentally important for remodeling cell walls and membranes. Here, we analyzed For1F, a novel gene that encodes a fusion of an exocyst subunit (Sec10) and an actin nucleation factor (formin). We showed that the fusion occurred early in moss evolution and has been retained for more than 170 million years. In Physcomitrella patens, For1F is essential, and the expressed protein is a fusion of Sec10 and formin. Reduction of For1F or actin filaments inhibits exocytosis, and For1F dynamically associates with Sec6, another exocyst subunit, in an actin-dependent manner. Complementation experiments demonstrate that constitutive expression of either half of the gene or the paralogous Sec10b rescues loss of For1F, suggesting that fusion of the two domains is not essential, consistent with findings in yeast, where formin and the exocyst are linked noncovalently. Although not essential, the fusion may have had selective advantages and provides a unique opportunity to probe actin regulation of exocytosis.
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Affiliation(s)
| | - Shu-Zon Wu
- Biological Sciences Department, Dartmouth College, Hanover, NH
| | - Mingqin Chang
- Biological Sciences Department, Dartmouth College, Hanover, NH.,Plant Biology Graduate Program, University of Massachusetts Amherst, Amherst, MA
| | - Kelli A Pattavina
- Molecular and Cellular Biology Graduate Program, University of Massachusetts Amherst, Amherst, MA
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54
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Du Y, Overdijk EJR, Berg JA, Govers F, Bouwmeester K. Solanaceous exocyst subunits are involved in immunity to diverse plant pathogens. JOURNAL OF EXPERIMENTAL BOTANY 2018; 69:655-666. [PMID: 29329405 PMCID: PMC5853398 DOI: 10.1093/jxb/erx442] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Accepted: 12/04/2017] [Indexed: 05/28/2023]
Abstract
The exocyst, a multiprotein complex consisting of eight subunits, plays an essential role in many biological processes by mediating secretion of post-Golgi-derived vesicles towards the plasma membrane. In recent years, roles for plant exocyst subunits in pathogen defence have been uncovered, largely based on studies in the model plant Arabidopsis. Only a few studies have been undertaken to assign the role of exocyst subunits in plant defence in other plants species, including crops. In this study, predicted protein sequences from exocyst subunits were retrieved by mining databases from the Solanaceous plants Nicotiana benthamiana, tomato, and potato. Subsequently, their evolutionary relationship with Arabidopsis exocyst subunits was analysed. Gene silencing in N. benthamiana showed that several exocyst subunits are required for proper plant defence against the (hemi-)biotrophic plant pathogens Phytophthora infestans and Pseudomonas syringae. In contrast, some exocyst subunits seem to act as susceptibility factors for the necrotrophic pathogen Botrytis cinerea. Furthermore, the majority of the exocyst subunits were found to be involved in callose deposition, suggesting that they play a role in basal plant defence. This study provides insight into the evolution of exocyst subunits in Solanaceous plants and is the first to show their role in immunity against multiple unrelated pathogens.
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Affiliation(s)
- Yu Du
- College of Horticulture, Northwest A&F University, Yangling, Shaanxi, China
- Laboratory of Phytopathology, Wageningen University & Research, Wageningen, The Netherlands
| | - Elysa J R Overdijk
- Laboratory of Phytopathology, Wageningen University & Research, Wageningen, The Netherlands
- Laboratory of Cell Biology, Wageningen University & Research, Wageningen, The Netherlands
| | - Jeroen A Berg
- Laboratory of Phytopathology, Wageningen University & Research, Wageningen, The Netherlands
| | - Francine Govers
- Laboratory of Phytopathology, Wageningen University & Research, Wageningen, The Netherlands
| | - Klaas Bouwmeester
- Laboratory of Phytopathology, Wageningen University & Research, Wageningen, The Netherlands
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55
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Białas A, Zess EK, De la Concepcion JC, Franceschetti M, Pennington HG, Yoshida K, Upson JL, Chanclud E, Wu CH, Langner T, Maqbool A, Varden FA, Derevnina L, Belhaj K, Fujisaki K, Saitoh H, Terauchi R, Banfield MJ, Kamoun S. Lessons in Effector and NLR Biology of Plant-Microbe Systems. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2018; 31:34-45. [PMID: 29144205 DOI: 10.1101/171223] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
A diversity of plant-associated organisms secrete effectors-proteins and metabolites that modulate plant physiology to favor host infection and colonization. However, effectors can also activate plant immune receptors, notably nucleotide-binding domain and leucine-rich repeat region (NLR)-containing proteins, enabling plants to fight off invading organisms. This interplay between effectors, their host targets, and the matching immune receptors is shaped by intricate molecular mechanisms and exceptionally dynamic coevolution. In this article, we focus on three effectors, AVR-Pik, AVR-Pia, and AVR-Pii, from the rice blast fungus Magnaporthe oryzae (syn. Pyricularia oryzae), and their corresponding rice NLR immune receptors, Pik, Pia, and Pii, to highlight general concepts of plant-microbe interactions. We draw 12 lessons in effector and NLR biology that have emerged from studying these three little effectors and are broadly applicable to other plant-microbe systems.
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Affiliation(s)
- Aleksandra Białas
- 1 The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Erin K Zess
- 1 The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | | | - Marina Franceschetti
- 2 Department of Biological Chemistry, John Innes Centre, Norwich, United Kingdom
| | - Helen G Pennington
- 1 The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Kentaro Yoshida
- 3 Graduate School of Agricultural Science, Kobe University, Kobe, Japan
| | - Jessica L Upson
- 1 The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Emilie Chanclud
- 1 The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Chih-Hang Wu
- 1 The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Thorsten Langner
- 1 The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Abbas Maqbool
- 1 The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Freya A Varden
- 2 Department of Biological Chemistry, John Innes Centre, Norwich, United Kingdom
| | - Lida Derevnina
- 1 The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Khaoula Belhaj
- 1 The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Koki Fujisaki
- 4 Iwate Biotechnology Research Center, Kitakami, Iwate, Japan; and
| | - Hiromasa Saitoh
- 4 Iwate Biotechnology Research Center, Kitakami, Iwate, Japan; and
- 5 Department of Molecular Microbiology, Tokyo University of Agriculture, Tokyo, Japan
| | - Ryohei Terauchi
- 3 Graduate School of Agricultural Science, Kobe University, Kobe, Japan
- 4 Iwate Biotechnology Research Center, Kitakami, Iwate, Japan; and
| | - Mark J Banfield
- 2 Department of Biological Chemistry, John Innes Centre, Norwich, United Kingdom
| | - Sophien Kamoun
- 1 The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
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56
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Leijon F, Melzer M, Zhou Q, Srivastava V, Bulone V. Proteomic Analysis of Plasmodesmata From Populus Cell Suspension Cultures in Relation With Callose Biosynthesis. FRONTIERS IN PLANT SCIENCE 2018; 9:1681. [PMID: 30510561 PMCID: PMC6252348 DOI: 10.3389/fpls.2018.01681] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Accepted: 10/29/2018] [Indexed: 05/19/2023]
Abstract
Plasmodesmata are channels that link adjacent cells in plant tissues through which molecular exchanges take place. They are involved in multiple processes vital to plant cells, such as responses to hormonal signaling or environmental challenges including osmotic stress, wounding and pathogen attack. Despite the importance of plasmodesmata, their proteome is not well-defined. Here, we have isolated fractions enriched in plasmodesmata from cell suspension cultures of Populus trichocarpa and identified 201 proteins that are enriched in these fractions, thereby providing further insight on the multiple functions of plasmodesmata. Proteomics analysis revealed an enrichment of proteins specifically involved in responses to stress, transport, metabolism and signal transduction. Consistent with the role of callose deposition and turnover in the closure and aperture of the plasmodesmata and our proteomic analysis, we demonstrate the enrichment of callose synthase activity in the plasmodesmata represented by several gene products. A new form of calcium-independent callose synthase activity was detected, in addition to the typical calcium-dependent enzyme activity, suggesting a role of calcium in the regulation of plasmodesmata through two forms of callose synthase activities. Our report provides the first proteomic investigation of the plasmodesmata from a tree species and the direct biochemical evidence for the occurrence of several forms of active callose synthases in these structures. Data are available via ProteomeXchange with identifier PXD010692.
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Affiliation(s)
- Felicia Leijon
- Division of Glycoscience, School of Engineering Sciences in Chemistry, Biotechnology and Health, Royal Institute of Technology, AlbaNova University Centre, Stockholm, Sweden
| | - Michael Melzer
- Leibniz Institute of Plant Genetics and Crop Plant Research, Gatersleben, Germany
| | - Qi Zhou
- Division of Glycoscience, School of Engineering Sciences in Chemistry, Biotechnology and Health, Royal Institute of Technology, AlbaNova University Centre, Stockholm, Sweden
| | - Vaibhav Srivastava
- Division of Glycoscience, School of Engineering Sciences in Chemistry, Biotechnology and Health, Royal Institute of Technology, AlbaNova University Centre, Stockholm, Sweden
- *Correspondence: Vaibhav Srivastava, Vincent Bulone,
| | - Vincent Bulone
- Division of Glycoscience, School of Engineering Sciences in Chemistry, Biotechnology and Health, Royal Institute of Technology, AlbaNova University Centre, Stockholm, Sweden
- ARC Centre of Excellence in Plant Cell Walls and School of Agriculture, Food and Wine, The University of Adelaide, Adelaide, SA, Australia
- *Correspondence: Vaibhav Srivastava, Vincent Bulone,
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57
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Białas A, Zess EK, De la Concepcion JC, Franceschetti M, Pennington HG, Yoshida K, Upson JL, Chanclud E, Wu CH, Langner T, Maqbool A, Varden FA, Derevnina L, Belhaj K, Fujisaki K, Saitoh H, Terauchi R, Banfield MJ, Kamoun S. Lessons in Effector and NLR Biology of Plant-Microbe Systems. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2018; 31:34-45. [PMID: 29144205 DOI: 10.1094/mpmi-08-17-0196-fi] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
A diversity of plant-associated organisms secrete effectors-proteins and metabolites that modulate plant physiology to favor host infection and colonization. However, effectors can also activate plant immune receptors, notably nucleotide-binding domain and leucine-rich repeat region (NLR)-containing proteins, enabling plants to fight off invading organisms. This interplay between effectors, their host targets, and the matching immune receptors is shaped by intricate molecular mechanisms and exceptionally dynamic coevolution. In this article, we focus on three effectors, AVR-Pik, AVR-Pia, and AVR-Pii, from the rice blast fungus Magnaporthe oryzae (syn. Pyricularia oryzae), and their corresponding rice NLR immune receptors, Pik, Pia, and Pii, to highlight general concepts of plant-microbe interactions. We draw 12 lessons in effector and NLR biology that have emerged from studying these three little effectors and are broadly applicable to other plant-microbe systems.
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Affiliation(s)
- Aleksandra Białas
- 1 The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Erin K Zess
- 1 The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | | | - Marina Franceschetti
- 2 Department of Biological Chemistry, John Innes Centre, Norwich, United Kingdom
| | - Helen G Pennington
- 1 The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Kentaro Yoshida
- 3 Graduate School of Agricultural Science, Kobe University, Kobe, Japan
| | - Jessica L Upson
- 1 The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Emilie Chanclud
- 1 The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Chih-Hang Wu
- 1 The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Thorsten Langner
- 1 The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Abbas Maqbool
- 1 The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Freya A Varden
- 2 Department of Biological Chemistry, John Innes Centre, Norwich, United Kingdom
| | - Lida Derevnina
- 1 The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Khaoula Belhaj
- 1 The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Koki Fujisaki
- 4 Iwate Biotechnology Research Center, Kitakami, Iwate, Japan; and
| | - Hiromasa Saitoh
- 4 Iwate Biotechnology Research Center, Kitakami, Iwate, Japan; and
- 5 Department of Molecular Microbiology, Tokyo University of Agriculture, Tokyo, Japan
| | - Ryohei Terauchi
- 3 Graduate School of Agricultural Science, Kobe University, Kobe, Japan
- 4 Iwate Biotechnology Research Center, Kitakami, Iwate, Japan; and
| | - Mark J Banfield
- 2 Department of Biological Chemistry, John Innes Centre, Norwich, United Kingdom
| | - Sophien Kamoun
- 1 The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
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58
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Wu C, Tan L, van Hooren M, Tan X, Liu F, Li Y, Zhao Y, Li B, Rui Q, Munnik T, Bao Y. Arabidopsis EXO70A1 recruits Patellin3 to the cell membrane independent of its role as an exocyst subunit. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2017; 59:851-865. [PMID: 28815958 DOI: 10.1111/jipb.12578] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2017] [Accepted: 08/14/2017] [Indexed: 06/07/2023]
Abstract
The exocyst is a well-known complex which tethers vesicles at the cell membrane before fusion. Whether an individual subunit can execute a unique function is largely unknown. Using yeast-two-hybrid (Y2H) analysis, we found that EXO70A1 interacted with the GOLD domain of Patellin3 (PATL3). The direct EXO70A1-PATL3 interaction was supported by in vitro and in vivo experiments. In Arabidopsis, PATL3-GFP colocalized with EXO70A1 predominantly at the cell membrane, and PATL3 localization was insensitive to BFA and TryA23. Remarkably, in the exo70a1 mutant, PATL3 proteins accumulated as punctate structures within the cytosol, which did not colocalize with several endomembrane compartment markers, and was insensitive to BFA. Furthermore, PATL3 localization was not changed in the exo70e2, PRsec6 or exo84b mutants. These data suggested that EXO70A1, but not other exocyst subunits, was responsible for PATL3 localization, which is independent of its role in secretory/recycling vesicle-tethering/fusion. Both EXO70A1 and PATL3 were shown to bind PI4P and PI(4,5)P2 in vitro. Evidence was obtained that the other four members of the PATL family bound to EXO70A1 as well, and shared a similar localization pattern as PATL3. These findings offered new insights into exocyst subunit-specific function, and provided data and tools for further characterization of PATL family proteins.
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Affiliation(s)
- Chengyun Wu
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Lu Tan
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Max van Hooren
- Department of Plant Cell Biology, Swammerdam Institute for Life Sciences (SILS), University of Amsterdam, Science park 904, 1098 XH, Amsterdam, The Netherlands
| | - Xiaoyun Tan
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Feng Liu
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Yan Li
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Yanxue Zhao
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Bingxuan Li
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Qingchen Rui
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Teun Munnik
- Department of Plant Cell Biology, Swammerdam Institute for Life Sciences (SILS), University of Amsterdam, Science park 904, 1098 XH, Amsterdam, The Netherlands
| | - Yiqun Bao
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
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59
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Mayers JR, Hu T, Wang C, Cárdenas JJ, Tan Y, Pan J, Bednarek SY. SCD1 and SCD2 Form a Complex That Functions with the Exocyst and RabE1 in Exocytosis and Cytokinesis. THE PLANT CELL 2017; 29:2610-2625. [PMID: 28970336 PMCID: PMC5774579 DOI: 10.1105/tpc.17.00409] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 09/12/2017] [Accepted: 09/26/2017] [Indexed: 05/21/2023]
Abstract
Although exocytosis is critical for the proper trafficking of materials to the plasma membrane, relatively little is known about the mechanistic details of post-Golgi trafficking in plants. Here, we demonstrate that the DENN (Differentially Expressed in Normal and Neoplastic cells) domain protein STOMATAL CYTOKINESIS DEFECTIVE1 (SCD1) and SCD2 form a previously unknown protein complex, the SCD complex, that functionally interacts with subunits of the exocyst complex and the RabE1 family of GTPases in Arabidopsis thaliana Consistent with a role in post-Golgi trafficking, scd1 and scd2 mutants display defects in exocytosis and recycling of PIN2-GFP. Perturbation of exocytosis using the small molecule Endosidin2 results in growth inhibition and PIN2-GFP trafficking defects in scd1 and scd2 mutants. In addition to the exocyst, the SCD complex binds in a nucleotide state-specific manner with Sec4p/Rab8-related RabE1 GTPases and overexpression of wild-type RabE1 rescues scd1 temperature-sensitive mutants. Furthermore, SCD1 colocalizes with the exocyst subunit, SEC15B, and RabE1 at the cell plate and in distinct punctae at or near the plasma membrane. Our findings reveal a mechanism for plant exocytosis, through the identification and characterization of a protein interaction network that includes the SCD complex, RabE1, and the exocyst.
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Affiliation(s)
| | - Tianwei Hu
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Chao Wang
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Jessica J Cárdenas
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - Yuqi Tan
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - Jianwei Pan
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
- College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, China
| | - Sebastian Y Bednarek
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
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60
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Rawat A, Brejšková L, Hála M, Cvrčková F, Žárský V. The Physcomitrella patens exocyst subunit EXO70.3d has distinct roles in growth and development, and is essential for completion of the moss life cycle. THE NEW PHYTOLOGIST 2017; 216:438-454. [PMID: 28397275 DOI: 10.1111/nph.14548] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 02/24/2017] [Indexed: 05/28/2023]
Abstract
The exocyst, an evolutionarily conserved secretory vesicle-tethering complex, spatially controls exocytosis and membrane turnover in fungi, metazoans and plants. The exocyst subunit EXO70 exists in multiple paralogs in land plants, forming three conserved clades with assumed distinct roles. Here we report functional analysis of the first moss exocyst subunit to be studied, Physcomitrella patens PpEXO70.3d (Pp1s97_91V6), from the, as yet, poorly characterized EXO70.3 clade. Following phylogenetic analysis to confirm the presence of three ancestral land plant EXO70 clades outside angiosperms, we prepared and phenotypically characterized loss-of-function Ppexo70.3d mutants and localized PpEXO70.3d in vivo using green fluorescent protein-tagged protein expression. Disruption of PpEXO70.3d caused pleiotropic cell elongation and differentiation defects in protonemata, altered response towards exogenous auxin, increased endogenous IAA concentrations, along with defects in bud and gametophore development. During mid-archegonia development, an abnormal egg cell is formed and subsequently collapses, resulting in mutant sterility. Mutants exhibited altered cell wall and cuticle deposition, as well as compromised cytokinesis, consistent with the protein localization to the cell plate. Despite some functional redundancy allowing survival of moss lacking PpEXO70.3d, this subunit has an essential role in the moss life cycle, indicating sub-functionalization within the moss EXO70 family.
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Affiliation(s)
- Anamika Rawat
- Laboratory of Cell Morphogenesis, Department of Experimental Plant Biology, Faculty of Science, Charles University, Viničná 5, 128 44, Prague 2, Czech Republic
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic, 165 02, Prague 6, Czech Republic
| | - Lucie Brejšková
- Laboratory of Cell Morphogenesis, Department of Experimental Plant Biology, Faculty of Science, Charles University, Viničná 5, 128 44, Prague 2, Czech Republic
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic, 165 02, Prague 6, Czech Republic
| | - Michal Hála
- Laboratory of Cell Morphogenesis, Department of Experimental Plant Biology, Faculty of Science, Charles University, Viničná 5, 128 44, Prague 2, Czech Republic
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic, 165 02, Prague 6, Czech Republic
| | - Fatima Cvrčková
- Laboratory of Cell Morphogenesis, Department of Experimental Plant Biology, Faculty of Science, Charles University, Viničná 5, 128 44, Prague 2, Czech Republic
| | - Viktor Žárský
- Laboratory of Cell Morphogenesis, Department of Experimental Plant Biology, Faculty of Science, Charles University, Viničná 5, 128 44, Prague 2, Czech Republic
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic, 165 02, Prague 6, Czech Republic
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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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Sabol P, Kulich I, Žárský V. RIN4 recruits the exocyst subunit EXO70B1 to the plasma membrane. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:3253-3265. [PMID: 28338727 PMCID: PMC5853926 DOI: 10.1093/jxb/erx007] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 01/09/2017] [Indexed: 05/22/2023]
Abstract
The exocyst is a conserved vesicle-tethering complex with principal roles in cell polarity and morphogenesis. Several studies point to its involvement in polarized secretion during microbial pathogen defense. In this context, we have found an interaction between the Arabidopsis EXO70B1 exocyst subunit, a protein which was previously associated with both the defense response and autophagy, and RPM1 INTERACTING PROTEIN 4 (RIN4), the best studied member of the NOI protein family and a known regulator of plant defense pathways. Interestingly, fragments of RIN4 mimicking the cleavage caused by the Pseudomonas syringae effector protease, AvrRpt2, fail to interact strongly with EXO70B1. We observed that transiently expressed RIN4, but not the plasma membrane (PM) protein aquaporin PIP2, recruits EXO70B1 to the PM. Unlike EXO70B1, RIN4 does not recruit the core exocyst subunit SEC6 to the PM under these conditions. Furthermore, the AvrRpt2 effector protease delivered by P. syringae is able to release both RIN4 and EXO70B1 to the cytoplasm. We present a model for how RIN4 might regulate the localization and putative function of EXO70B1 and speculate on the role the AvrRpt2 protease might have in the regulation of this defense response.
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Affiliation(s)
- Peter Sabol
- Charles University in Prague, Viničná, Prague, Czech Republic
| | - Ivan Kulich
- Charles University in Prague, Viničná, Prague, Czech Republic
- Correspondence:
| | - Viktor Žárský
- Charles University in Prague, Viničná, Prague, Czech Republic
- Institute of Experimental Botany, Rozvojová, Prague, Czech Republic
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63
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Synek L, Vukašinović N, Kulich I, Hála M, Aldorfová K, Fendrych M, Žárský V. EXO70C2 Is a Key Regulatory Factor for Optimal Tip Growth of Pollen. PLANT PHYSIOLOGY 2017; 174:223-240. [PMID: 28356503 PMCID: PMC5411130 DOI: 10.1104/pp.16.01282] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 03/25/2017] [Indexed: 05/21/2023]
Abstract
The exocyst, a eukaryotic tethering complex, coregulates targeted exocytosis as an effector of small GTPases in polarized cell growth. In land plants, several exocyst subunits are encoded by double or triple paralogs, culminating in tens of EXO70 paralogs. Out of 23 Arabidopsis thaliana EXO70 isoforms, we analyzed seven isoforms expressed in pollen. Genetic and microscopic analyses of single mutants in EXO70A2, EXO70C1, EXO70C2, EXO70F1, EXO70H3, EXO70H5, and EXO70H6 genes revealed that only a loss-of-function EXO70C2 allele resulted in a significant male-specific transmission defect (segregation 40%:51%:9%) due to aberrant pollen tube growth. Mutant pollen tubes grown in vitro exhibited an enhanced growth rate and a decreased thickness of the tip cell wall, causing tip bursts. However, exo70C2 pollen tubes could frequently recover and restart their speedy elongation, resulting in a repetitive stop-and-go growth dynamics. A pollen-specific depletion of the closest paralog, EXO70C1, using artificial microRNA in the exo70C2 mutant background, resulted in a complete pollen-specific transmission defect, suggesting redundant functions of EXO70C1 and EXO70C2. Both EXO70C1 and EXO70C2, GFP tagged and expressed under the control of their native promoters, localized in the cytoplasm of pollen grains, pollen tubes, and also root trichoblast cells. The expression of EXO70C2-GFP complemented the aberrant growth of exo70C2 pollen tubes. The absent EXO70C2 interactions with core exocyst subunits in the yeast two-hybrid assay, cytoplasmic localization, and genetic effect suggest an unconventional EXO70 function possibly as a regulator of exocytosis outside the exocyst complex. In conclusion, EXO70C2 is a novel factor contributing to the regulation of optimal tip growth of Arabidopsis pollen tubes.
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Affiliation(s)
- Lukáš Synek
- Institute of Experimental Botany, Czech Academy of Sciences, 16502 Prague 6, Czech Republic (L.S., N.V., M.H., K.A., M.F., V.Ž.); and
- Department of Experimental Botany, Faculty of Science, Charles University, 12844 Prague 2, Czech Republic (I.K., M.H., K.A., V.Ž.)
| | - Nemanja Vukašinović
- Institute of Experimental Botany, Czech Academy of Sciences, 16502 Prague 6, Czech Republic (L.S., N.V., M.H., K.A., M.F., V.Ž.); and
- Department of Experimental Botany, Faculty of Science, Charles University, 12844 Prague 2, Czech Republic (I.K., M.H., K.A., V.Ž.)
| | - Ivan Kulich
- Institute of Experimental Botany, Czech Academy of Sciences, 16502 Prague 6, Czech Republic (L.S., N.V., M.H., K.A., M.F., V.Ž.); and
- Department of Experimental Botany, Faculty of Science, Charles University, 12844 Prague 2, Czech Republic (I.K., M.H., K.A., V.Ž.)
| | - Michal Hála
- Institute of Experimental Botany, Czech Academy of Sciences, 16502 Prague 6, Czech Republic (L.S., N.V., M.H., K.A., M.F., V.Ž.); and
- Department of Experimental Botany, Faculty of Science, Charles University, 12844 Prague 2, Czech Republic (I.K., M.H., K.A., V.Ž.)
| | - Klára Aldorfová
- Institute of Experimental Botany, Czech Academy of Sciences, 16502 Prague 6, Czech Republic (L.S., N.V., M.H., K.A., M.F., V.Ž.); and
- Department of Experimental Botany, Faculty of Science, Charles University, 12844 Prague 2, Czech Republic (I.K., M.H., K.A., V.Ž.)
| | - Matyáš Fendrych
- Institute of Experimental Botany, Czech Academy of Sciences, 16502 Prague 6, Czech Republic (L.S., N.V., M.H., K.A., M.F., V.Ž.); and
- Department of Experimental Botany, Faculty of Science, Charles University, 12844 Prague 2, Czech Republic (I.K., M.H., K.A., V.Ž.)
| | - Viktor Žárský
- Institute of Experimental Botany, Czech Academy of Sciences, 16502 Prague 6, Czech Republic (L.S., N.V., M.H., K.A., M.F., V.Ž.); and
- Department of Experimental Botany, Faculty of Science, Charles University, 12844 Prague 2, Czech Republic (I.K., M.H., K.A., V.Ž.)
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Kalmbach L, Hématy K, De Bellis D, Barberon M, Fujita S, Ursache R, Daraspe J, Geldner N. Transient cell-specific EXO70A1 activity in the CASP domain and Casparian strip localization. NATURE PLANTS 2017; 3:17058. [PMID: 28436943 DOI: 10.1038/nplants.2017.58] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Accepted: 03/24/2017] [Indexed: 06/07/2023]
Abstract
In a striking case of evolutionary convergence, polarized cell layers with ring-like diffusion barriers have evolved in both plant and animal lineages independently. In plants, ring-like Casparian strips become localized by the CASPARIAN STRIP MEMBRANE DOMAIN PROTEINS (CASPs). The mechanism of this striking localization, however, has remained enigmatic. Here we present a genetic screen aimed at isolating determinants of CASP localization. One of the mutants, lord of the rings 2 (lotr2)/exo70a1, displays dramatic de-localization of CASPs into randomly localized microdomains. EXO70A1 is a subunit of the exocyst complex, a central component of secretion in eukaryotes. Irradiation of EXO70 subunit genes in plants has suggested specialization of this conserved complex. Intriguingly, lotr2/exo70a1 does neither affect secretion of the CASPs, nor that of other membrane proteins in the endodermis, thus separating exocyst activity in localization from a general defect in secretion. Our results establish EXO70A1 as a central player in Casparian strip formation, generating a transient positional information that will be translated into a precisely localized cell wall modification.
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Affiliation(s)
- Lothar Kalmbach
- Department of Plant Molecular Biology, University of Lausanne, Biophore Building, UNIL-Sorge, 1015 Lausanne, Switzerland
| | - Kian Hématy
- Department of Plant Molecular Biology, University of Lausanne, Biophore Building, UNIL-Sorge, 1015 Lausanne, Switzerland
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, 78000 Versailles, France
| | - Damien De Bellis
- Department of Plant Molecular Biology, University of Lausanne, Biophore Building, UNIL-Sorge, 1015 Lausanne, Switzerland
- Electron Microscopy Facility, University of Lausanne, Biophore Building, UNIL-Sorge, 1015 Lausanne, Switzerland
| | - Marie Barberon
- Department of Plant Molecular Biology, University of Lausanne, Biophore Building, UNIL-Sorge, 1015 Lausanne, Switzerland
| | - Satoshi Fujita
- Department of Plant Molecular Biology, University of Lausanne, Biophore Building, UNIL-Sorge, 1015 Lausanne, Switzerland
| | - Robertas Ursache
- Department of Plant Molecular Biology, University of Lausanne, Biophore Building, UNIL-Sorge, 1015 Lausanne, Switzerland
| | - Jean Daraspe
- Electron Microscopy Facility, University of Lausanne, Biophore Building, UNIL-Sorge, 1015 Lausanne, Switzerland
| | - Niko Geldner
- Department of Plant Molecular Biology, University of Lausanne, Biophore Building, UNIL-Sorge, 1015 Lausanne, Switzerland
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65
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Sekereš J, Pejchar P, Šantrůček J, Vukašinović N, Žárský V, Potocký M. Analysis of Exocyst Subunit EXO70 Family Reveals Distinct Membrane Polar Domains in Tobacco Pollen Tubes. PLANT PHYSIOLOGY 2017; 173:1659-1675. [PMID: 28082718 PMCID: PMC5338673 DOI: 10.1104/pp.16.01709] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 01/10/2017] [Indexed: 05/05/2023]
Abstract
The vesicle-tethering complex exocyst is one of the crucial cell polarity regulators. The EXO70 subunit is required for the targeting of the complex and is represented by many isoforms in angiosperm plant cells. This diversity could be partly responsible for the establishment and maintenance of membrane domains with different composition. To address this hypothesis, we employed the growing pollen tube, a well-established cell polarity model system, and performed large-scale expression, localization, and functional analysis of tobacco (Nicotiana tabacum) EXO70 isoforms. Various isoforms localized to different regions of the pollen tube plasma membrane, apical vesicle-rich inverted cone region, nucleus, and cytoplasm. The overexpression of major pollen-expressed EXO70 isoforms resulted in growth arrest and characteristic phenotypic deviations of tip swelling and apical invaginations. NtEXO70A1a and NtEXO70B1 occupied two distinct and mutually exclusive plasma membrane domains. Both isoforms partly colocalized with the exocyst subunit NtSEC3a at the plasma membrane, possibly forming different exocyst complex subpopulations. NtEXO70A1a localized to the small area previously characterized as the site of exocytosis in the tobacco pollen tube, while NtEXO70B1 surprisingly colocalized with the zone of clathrin-mediated endocytosis. Both NtEXO70A1a and NtEXO70B1 colocalized to different degrees with markers for the anionic signaling phospholipids phosphatidylinositol 4,5-bisphosphate and phosphatidic acid. In contrast, members of the EXO70 C class, which are specifically expressed in tip-growing cells, exhibited exocytosis-related functional effects in pollen tubes despite the absence of apparent plasma membrane localization. Taken together, our data support the existence of multiple membrane-trafficking domains regulated by different EXO70-containing exocyst complexes within a single cell.
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Affiliation(s)
- Juraj Sekereš
- Institute of Experimental Botany, Czech Academy of Sciences, Prague 6, Czech Republic (J.S., P.P., N.V., V.Ž., M.P.)
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague 2, Czech Republic (J.S., V.Ž.); and
- Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague 6, Czech Republic (J.Š.)
| | - Přemysl Pejchar
- Institute of Experimental Botany, Czech Academy of Sciences, Prague 6, Czech Republic (J.S., P.P., N.V., V.Ž., M.P.)
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague 2, Czech Republic (J.S., V.Ž.); and
- Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague 6, Czech Republic (J.Š.)
| | - Jiří Šantrůček
- Institute of Experimental Botany, Czech Academy of Sciences, Prague 6, Czech Republic (J.S., P.P., N.V., V.Ž., M.P.)
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague 2, Czech Republic (J.S., V.Ž.); and
- Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague 6, Czech Republic (J.Š.)
| | - Nemanja Vukašinović
- Institute of Experimental Botany, Czech Academy of Sciences, Prague 6, Czech Republic (J.S., P.P., N.V., V.Ž., M.P.)
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague 2, Czech Republic (J.S., V.Ž.); and
- Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague 6, Czech Republic (J.Š.)
| | - Viktor Žárský
- Institute of Experimental Botany, Czech Academy of Sciences, Prague 6, Czech Republic (J.S., P.P., N.V., V.Ž., M.P.)
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague 2, Czech Republic (J.S., V.Ž.); and
- Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague 6, Czech Republic (J.Š.)
| | - Martin Potocký
- Institute of Experimental Botany, Czech Academy of Sciences, Prague 6, Czech Republic (J.S., P.P., N.V., V.Ž., M.P.);
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague 2, Czech Republic (J.S., V.Ž.); and
- Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague 6, Czech Republic (J.Š.)
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Vukašinović N, Oda Y, Pejchar P, Synek L, Pečenková T, Rawat A, Sekereš J, Potocký M, Žárský V. Microtubule-dependent targeting of the exocyst complex is necessary for xylem development in Arabidopsis. THE NEW PHYTOLOGIST 2017; 213:1052-1067. [PMID: 27801942 DOI: 10.1111/nph.14267] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 09/13/2016] [Indexed: 05/23/2023]
Abstract
Cortical microtubules (MTs) play a major role in the patterning of secondary cell wall (SCW) thickenings in tracheary elements (TEs) by determining the sites of SCW deposition. The EXO70A1 subunit of the exocyst secretory vesicle tethering complex was implicated to be important for TE development via the MT interaction. We investigated the subcellular localization of several exocyst subunits in the xylem of Arabidopsis thaliana and analyzed the functional significance of exocyst-mediated trafficking in TE development. Live cell imaging of fluorescently tagged exocyst subunits in TE using confocal microscopy and protein-protein interaction assays were performed to describe the role of the exocyst and its partners in TE development. In TEs, exocyst subunits were localized to the sites of SCW deposition in an MT-dependent manner. We propose that the mechanism of exocyst targeting to MTs involves the direct interaction of exocyst subunits with the COG2 protein. We demonstrated the importance of a functional exocyst subunit EXO84b for normal TE development and showed that the deposition of SCW constituents is partially compromised, possibly as a result of the mislocalization of secondary cellulose synthase in exocyst mutants. We conclude that the exocyst complex is an important factor bridging the pattern defined by cortical MTs with localized secretion of the SCW in developing TEs.
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Affiliation(s)
- Nemanja Vukašinović
- Institute of Experimental Botany, v.v.i., The Czech Academy of Sciences, 16502, Prague 6, Czech Republic
- Department of Experimental Plant Biology, Faculty of Science, Charles University in Prague, 128 44, Prague 2, Czech Republic
| | - Yoshihisa Oda
- Center for Frontier Research, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka, 411-8540, Japan
- Department of Genetics, School of Life Science, SOKENDAI (Graduate University for Advanced Studies), 1111 Yata, Mishima, Shizuoka, 411-8540, Japan
| | - Přemysl Pejchar
- Institute of Experimental Botany, v.v.i., The Czech Academy of Sciences, 16502, Prague 6, Czech Republic
| | - Lukáš Synek
- Institute of Experimental Botany, v.v.i., The Czech Academy of Sciences, 16502, Prague 6, Czech Republic
| | - Tamara Pečenková
- Institute of Experimental Botany, v.v.i., The Czech Academy of Sciences, 16502, Prague 6, Czech Republic
| | - Anamika Rawat
- Institute of Experimental Botany, v.v.i., The Czech Academy of Sciences, 16502, Prague 6, Czech Republic
- Department of Experimental Plant Biology, Faculty of Science, Charles University in Prague, 128 44, Prague 2, Czech Republic
| | - Juraj Sekereš
- Institute of Experimental Botany, v.v.i., The Czech Academy of Sciences, 16502, Prague 6, Czech Republic
- Department of Experimental Plant Biology, Faculty of Science, Charles University in Prague, 128 44, Prague 2, Czech Republic
| | - Martin Potocký
- Institute of Experimental Botany, v.v.i., The Czech Academy of Sciences, 16502, Prague 6, Czech Republic
| | - Viktor Žárský
- Institute of Experimental Botany, v.v.i., The Czech Academy of Sciences, 16502, Prague 6, Czech Republic
- Department of Experimental Plant Biology, Faculty of Science, Charles University in Prague, 128 44, Prague 2, Czech Republic
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67
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Seo DH, Ahn MY, Park KY, Kim EY, Kim WT. The N-Terminal UND Motif of the Arabidopsis U-Box E3 Ligase PUB18 Is Critical for the Negative Regulation of ABA-Mediated Stomatal Movement and Determines Its Ubiquitination Specificity for Exocyst Subunit Exo70B1. THE PLANT CELL 2016; 28:2952-2973. [PMID: 27956469 PMCID: PMC5240735 DOI: 10.1105/tpc.16.00347] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Revised: 11/18/2016] [Accepted: 12/09/2016] [Indexed: 05/20/2023]
Abstract
The Arabidopsis thaliana U-box E3 ligases PUB18/PUB19 and PUB22/PUB23 are negative regulators of drought stress responses. PUB18/PUB19 regulate the drought stress response in an abscisic acid (ABA)-dependent manner, whereas PUB22/PUB23 regulate this response in an ABA-independent manner. A major structural difference between PUB18/PUB19 and PUB22/PUB23 is the presence of the UND (U-box N-terminal domain). Here, we focused on elucidating the molecular mechanism that mediates the functional difference between PUB18 and PUB22 and found that the UNDPUB18 was critically involved in the negative regulation of ABA-mediated stomatal movements. Exo70B1, a subunit of the exocyst complex, was identified as a target of PUB18, whereas Exo70B2 was a substrate of PUB22. However, the ∆UND-PUB18 derivative failed to ubiquitinate Exo70B1, but ubiquitinated Exo70B2. By contrast, the UNDPUB18-PUB22 chimeric protein ubiquitinated Exo70B1 instead of Exo70B2, suggesting that the ubiquitination specificities of PUB18 and PUB22 to Exo70B1 and Exo70B2, respectively, are dependent on the presence or absence of the UNDPUB18 motif. The ABA-insensitive phenotypes of the pub18 pub19 exo70b1 triple mutant were reminiscent of those of exo70b1 rather than pub18 pub19, indicating that Exo70B1 functions downstream of PUB18. Overall, our results suggest that the UNDPUB18 motif is crucial for the negative regulation of ABA-dependent stomatal movement and for determination of its ubiquitination specificity to Exo70B1.
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Affiliation(s)
- Dong Hye Seo
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Min Yong Ahn
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Ki Youl Park
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Eun Yu Kim
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Woo Taek Kim
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
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68
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Bloch D, Pleskot R, Pejchar P, Potocký M, Trpkošová P, Cwiklik L, Vukašinović N, Sternberg H, Yalovsky S, Žárský V. Exocyst SEC3 and Phosphoinositides Define Sites of Exocytosis in Pollen Tube Initiation and Growth. PLANT PHYSIOLOGY 2016; 172:980-1002. [PMID: 27516531 PMCID: PMC5047084 DOI: 10.1104/pp.16.00690] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 08/08/2016] [Indexed: 05/16/2023]
Abstract
Polarized exocytosis is critical for pollen tube growth, but its localization and function are still under debate. The exocyst vesicle-tethering complex functions in polarized exocytosis. Here, we show that a sec3a exocyst subunit null mutant cannot be transmitted through the male gametophyte due to a defect in pollen tube growth. The green fluorescent protein (GFP)-SEC3a fusion protein is functional and accumulates at or proximal to the pollen tube tip plasma membrane. Partial complementation of sec3a resulted in the development of pollen with multiple tips, indicating that SEC3 is required to determine the site of pollen germination pore formation. Time-lapse imaging demonstrated that SEC3a and SEC8 were highly dynamic and that SEC3a localization on the apical plasma membrane predicts the direction of growth. At the tip, polar SEC3a domains coincided with cell wall deposition. Labeling of GFP-SEC3a-expressing pollen with the endocytic marker FM4-64 revealed the presence of subdomains on the apical membrane characterized by extensive exocytosis. In steady-state growing tobacco (Nicotiana tabacum) pollen tubes, SEC3a displayed amino-terminal Pleckstrin homology-like domain (SEC3a-N)-dependent subapical membrane localization. In agreement, SEC3a-N interacted with phosphoinositides in vitro and colocalized with a phosphatidylinositol 4,5-bisphosphate (PIP2) marker in pollen tubes. Correspondingly, molecular dynamics simulations indicated that SEC3a-N associates with the membrane by interacting with PIP2 However, the interaction with PIP2 is not required for polar localization and the function of SEC3a in Arabidopsis (Arabidopsis thaliana). Taken together, our findings indicate that SEC3a is a critical determinant of polar exocytosis during tip growth and suggest differential regulation of the exocytotic machinery depending on pollen tube growth modes.
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Affiliation(s)
- Daria Bloch
- Department of Molecular Biology and Ecology of Plants, Tel Aviv University, Tel Aviv 69978, Israel (D.B., H.S., S.Y.);Institute of Experimental Botany, Czech Academy of Sciences, 165 02 Prague, Czech Republic (R.P., P.P., M.P., P.T., N.V., V.Ž.);J. Heyrovsky Institute of Physical Chemistry, Czech Academy of Sciences, 182 23 Prague, Czech Republic (L.C.); andDepartment of Experimental Plant Biology, Faculty of Science, Charles University, 128 44 Prague, Czech Republic (N.V., V.Ž.)
| | - Roman Pleskot
- Department of Molecular Biology and Ecology of Plants, Tel Aviv University, Tel Aviv 69978, Israel (D.B., H.S., S.Y.);Institute of Experimental Botany, Czech Academy of Sciences, 165 02 Prague, Czech Republic (R.P., P.P., M.P., P.T., N.V., V.Ž.);J. Heyrovsky Institute of Physical Chemistry, Czech Academy of Sciences, 182 23 Prague, Czech Republic (L.C.); andDepartment of Experimental Plant Biology, Faculty of Science, Charles University, 128 44 Prague, Czech Republic (N.V., V.Ž.)
| | - Přemysl Pejchar
- Department of Molecular Biology and Ecology of Plants, Tel Aviv University, Tel Aviv 69978, Israel (D.B., H.S., S.Y.);Institute of Experimental Botany, Czech Academy of Sciences, 165 02 Prague, Czech Republic (R.P., P.P., M.P., P.T., N.V., V.Ž.);J. Heyrovsky Institute of Physical Chemistry, Czech Academy of Sciences, 182 23 Prague, Czech Republic (L.C.); andDepartment of Experimental Plant Biology, Faculty of Science, Charles University, 128 44 Prague, Czech Republic (N.V., V.Ž.)
| | - Martin Potocký
- Department of Molecular Biology and Ecology of Plants, Tel Aviv University, Tel Aviv 69978, Israel (D.B., H.S., S.Y.);Institute of Experimental Botany, Czech Academy of Sciences, 165 02 Prague, Czech Republic (R.P., P.P., M.P., P.T., N.V., V.Ž.);J. Heyrovsky Institute of Physical Chemistry, Czech Academy of Sciences, 182 23 Prague, Czech Republic (L.C.); andDepartment of Experimental Plant Biology, Faculty of Science, Charles University, 128 44 Prague, Czech Republic (N.V., V.Ž.)
| | - Pavlína Trpkošová
- Department of Molecular Biology and Ecology of Plants, Tel Aviv University, Tel Aviv 69978, Israel (D.B., H.S., S.Y.);Institute of Experimental Botany, Czech Academy of Sciences, 165 02 Prague, Czech Republic (R.P., P.P., M.P., P.T., N.V., V.Ž.);J. Heyrovsky Institute of Physical Chemistry, Czech Academy of Sciences, 182 23 Prague, Czech Republic (L.C.); andDepartment of Experimental Plant Biology, Faculty of Science, Charles University, 128 44 Prague, Czech Republic (N.V., V.Ž.)
| | - Lukasz Cwiklik
- Department of Molecular Biology and Ecology of Plants, Tel Aviv University, Tel Aviv 69978, Israel (D.B., H.S., S.Y.);Institute of Experimental Botany, Czech Academy of Sciences, 165 02 Prague, Czech Republic (R.P., P.P., M.P., P.T., N.V., V.Ž.);J. Heyrovsky Institute of Physical Chemistry, Czech Academy of Sciences, 182 23 Prague, Czech Republic (L.C.); andDepartment of Experimental Plant Biology, Faculty of Science, Charles University, 128 44 Prague, Czech Republic (N.V., V.Ž.)
| | - Nemanja Vukašinović
- Department of Molecular Biology and Ecology of Plants, Tel Aviv University, Tel Aviv 69978, Israel (D.B., H.S., S.Y.);Institute of Experimental Botany, Czech Academy of Sciences, 165 02 Prague, Czech Republic (R.P., P.P., M.P., P.T., N.V., V.Ž.);J. Heyrovsky Institute of Physical Chemistry, Czech Academy of Sciences, 182 23 Prague, Czech Republic (L.C.); andDepartment of Experimental Plant Biology, Faculty of Science, Charles University, 128 44 Prague, Czech Republic (N.V., V.Ž.)
| | - Hasana Sternberg
- Department of Molecular Biology and Ecology of Plants, Tel Aviv University, Tel Aviv 69978, Israel (D.B., H.S., S.Y.);Institute of Experimental Botany, Czech Academy of Sciences, 165 02 Prague, Czech Republic (R.P., P.P., M.P., P.T., N.V., V.Ž.);J. Heyrovsky Institute of Physical Chemistry, Czech Academy of Sciences, 182 23 Prague, Czech Republic (L.C.); andDepartment of Experimental Plant Biology, Faculty of Science, Charles University, 128 44 Prague, Czech Republic (N.V., V.Ž.)
| | - Shaul Yalovsky
- Department of Molecular Biology and Ecology of Plants, Tel Aviv University, Tel Aviv 69978, Israel (D.B., H.S., S.Y.);Institute of Experimental Botany, Czech Academy of Sciences, 165 02 Prague, Czech Republic (R.P., P.P., M.P., P.T., N.V., V.Ž.);J. Heyrovsky Institute of Physical Chemistry, Czech Academy of Sciences, 182 23 Prague, Czech Republic (L.C.); andDepartment of Experimental Plant Biology, Faculty of Science, Charles University, 128 44 Prague, Czech Republic (N.V., V.Ž.)
| | - Viktor Žárský
- Department of Molecular Biology and Ecology of Plants, Tel Aviv University, Tel Aviv 69978, Israel (D.B., H.S., S.Y.);Institute of Experimental Botany, Czech Academy of Sciences, 165 02 Prague, Czech Republic (R.P., P.P., M.P., P.T., N.V., V.Ž.);J. Heyrovsky Institute of Physical Chemistry, Czech Academy of Sciences, 182 23 Prague, Czech Republic (L.C.); andDepartment of Experimental Plant Biology, Faculty of Science, Charles University, 128 44 Prague, Czech Republic (N.V., V.Ž.)
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69
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Vukašinović N, Žárský V. Tethering Complexes in the Arabidopsis Endomembrane System. Front Cell Dev Biol 2016; 4:46. [PMID: 27243010 PMCID: PMC4871884 DOI: 10.3389/fcell.2016.00046] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 05/02/2016] [Indexed: 12/30/2022] Open
Abstract
Targeting of endomembrane transport containers is of the utmost importance for proper land plant growth and development. Given the immobility of plant cells, localized membrane vesicle secretion and recycling are amongst the main processes guiding proper cell, tissue and whole plant morphogenesis. Cell wall biogenesis and modification are dependent on vectorial membrane traffic, not only during normal development, but also in stress responses and in plant defense against pathogens and/or symbiosis. It is surprising how little we know about these processes in plants, from small GTPase regulation to the tethering complexes that act as their effectors. Tethering factors are single proteins or protein complexes mediating first contact between the target membrane and arriving membrane vesicles. In this review we focus on the tethering complexes of the best-studied plant model—Arabidopsis thaliana. Genome-based predictions indicate the presence of all major tethering complexes in plants that are known from a hypothetical last eukaryotic common ancestor (LECA). The evolutionary multiplication of paralogs of plant tethering complex subunits has produced the massively expanded EXO70 family, indicating a subfunctionalization of the terminal exocytosis machinery in land plants. Interpretation of loss of function (LOF) mutant phenotypes has to consider that related, yet clearly functionally-specific complexes often share some common core subunits. It is therefore impossible to conclude with clarity which version of the complex is responsible for the phenotypic deviations observed. Experimental interest in the analysis of plant tethering complexes is growing and we hope to contribute with this review by attracting even more attention to this fascinating field of plant cell biology.
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Affiliation(s)
- Nemanja Vukašinović
- Laboratory of Cell Morphogenesis, Department of Experimental Plant Biology, Faculty of Science, Charles University Prague, Czech Republic
| | - Viktor Žárský
- Laboratory of Cell Morphogenesis, Department of Experimental Plant Biology, Faculty of Science, Charles University Prague, Czech Republic
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70
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Martin-Urdiroz M, Deeks MJ, Horton CG, Dawe HR, Jourdain I. The Exocyst Complex in Health and Disease. Front Cell Dev Biol 2016; 4:24. [PMID: 27148529 PMCID: PMC4828438 DOI: 10.3389/fcell.2016.00024] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Accepted: 03/11/2016] [Indexed: 01/23/2023] Open
Abstract
Exocytosis involves the fusion of intracellular secretory vesicles with the plasma membrane, thereby delivering integral membrane proteins to the cell surface and releasing material into the extracellular space. Importantly, exocytosis also provides a source of lipid moieties for membrane extension. The tethering of the secretory vesicle before docking and fusion with the plasma membrane is mediated by the exocyst complex, an evolutionary conserved octameric complex of proteins. Recent findings indicate that the exocyst complex also takes part in other intra-cellular processes besides secretion. These various functions seem to converge toward defining a direction of membrane growth in a range of systems from fungi to plants and from neurons to cilia. In this review we summarize the current knowledge of exocyst function in cell polarity, signaling and cell-cell communication and discuss implications for plant and animal health and disease.
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Affiliation(s)
| | - Michael J Deeks
- Biosciences, College of Life and Environmental Sciences, University of Exeter Exeter, UK
| | - Connor G Horton
- Biosciences, College of Life and Environmental Sciences, University of Exeter Exeter, UK
| | - Helen R Dawe
- Biosciences, College of Life and Environmental Sciences, University of Exeter Exeter, UK
| | - Isabelle Jourdain
- Biosciences, College of Life and Environmental Sciences, University of Exeter Exeter, UK
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71
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Kim SJ, Brandizzi F. The plant secretory pathway for the trafficking of cell wall polysaccharides and glycoproteins. Glycobiology 2016; 26:940-949. [PMID: 27072815 DOI: 10.1093/glycob/cww044] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 04/03/2016] [Indexed: 01/22/2023] Open
Abstract
Plant endomembranes are required for the biosynthesis and secretion of complex cell wall matrix polysaccharides, glycoproteins and proteoglycans. To define the biochemical roadmap that guides the synthesis and deposition of these cell wall components it is first necessary to outline the localization of the biosynthetic and modifying enzymes involved, as well as the distribution of the intermediate and final constituents of the cell wall. Thus far, a comprehensive understanding of cell wall matrix components has been hampered by the multiplicity of trafficking routes in the secretory pathway, and the diverse biosynthetic roles of the endomembrane organelles, which may exhibit tissue and development specific features. However, the recent identification of protein complexes producing matrix polysaccharides, and those supporting the synthesis and distribution of a grass-specific hemicellulose are advancing our understanding of the functional contribution of the plant secretory pathway in cell wall biosynthesis. In this review, we provide an overview of the plant membrane trafficking routes and report on recent exciting accomplishments in the understanding of the mechanisms underlying secretion with focus on cell wall synthesis in plants.
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Affiliation(s)
- Sang-Jin Kim
- Great Lakes Bioenergy Research Center Michigan State University-DOE Plant Research Laboratory
| | - Federica Brandizzi
- Great Lakes Bioenergy Research Center Michigan State University-DOE Plant Research Laboratory Department of Plant Biology, Michigan State University, East Lansing, MI, USA
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72
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Ma J, Cheng Z, Chen J, Shen J, Zhang B, Ren Y, Ding Y, Zhou Y, Zhang H, Zhou K, Wang JL, Lei C, Zhang X, Guo X, Gao H, Bao Y, Wan JM. Phosphatidylserine Synthase Controls Cell Elongation Especially in the Uppermost Internode in Rice by Regulation of Exocytosis. PLoS One 2016; 11:e0153119. [PMID: 27055010 PMCID: PMC4824389 DOI: 10.1371/journal.pone.0153119] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 03/23/2016] [Indexed: 11/18/2022] Open
Abstract
The uppermost internode is one of the fastest elongating organs in rice, and is expected to require an adequate supply of cell-wall materials and enzymes to the cell surface to enhance mechanical strength. Although it has been reported that the phenotype of shortened uppermost internode 1 (sui1) is caused by mutations in PHOSPHATIDYLSERINE SYNTHASE (OsPSS), the underlying mechanism remains unclear. Here we show that the OsPSS-1, as a gene expressed predominantly in elongating cells, regulates post-Golgi vesicle secretion to intercellular spaces. Mutation of OsPSS-1 leads to compromised delivery of CESA4 and secGFP towards the cell surface, resulting in weakened intercellular adhesion and disorganized cell arrangement in parenchyma. The phenotype of sui1-4 is caused largely by the reduction in cellulose contents in the whole plant and detrimental delivery of pectins in the uppermost internode. We found that OsPSS-1 and its potential product PS (phosphatidylserine) localized to organelles associated with exocytosis. These results together suggest that OsPSS-1 plays a potential role in mediating cell expansion by regulating secretion of cell wall components.
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Affiliation(s)
- Jin Ma
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Zhijun Cheng
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing, China
- * E-mail: (ZJC); (JMW)
| | - Jun Chen
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Jinbo Shen
- School of Life Sciences, Centre for Cell and Developmental Biology, Chinese University of Hong Kong, New Territories, Hong Kong, China
| | - Baocai Zhang
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Yulong Ren
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Yu Ding
- School of Life Sciences, Centre for Cell and Developmental Biology, Chinese University of Hong Kong, New Territories, Hong Kong, China
| | - Yihua Zhou
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Huan Zhang
- National Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, China
| | - Kunneng Zhou
- National Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, China
| | - Jiu-Lin Wang
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Cailin Lei
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Xin Zhang
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Xiuping Guo
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - He Gao
- National Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, China
| | - Yiqun Bao
- National Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, China
| | - Jian-Min Wan
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing, China
- National Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, China
- * E-mail: (ZJC); (JMW)
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Abstract
Unconventional protein secretion (UPS) describes secretion pathways that bypass one or several of the canonical secretion pit-stops on the way to the plasma membrane, and/or involve the secretion of leaderless proteins. So far, alternatives to conventional secretion were primarily observed and studied in yeast and animal cells. The sessile lifestyle of plants brings with it unique restraints on how they adapt to adverse conditions and environmental challenges. Recently, attention towards unconventional secretion pathways in plant cells has substantially increased, with the large number of leaderless proteins identified through proteomic studies. While UPS pathways in plants are certainly not yet exhaustively researched, an emerging notion is that induction of UPS pathways is correlated with pathogenesis and stress responses. Given the multitude UPS events observed, comprehensively organizing the routes proteins take to the apoplast in defined UPS categories is challenging. With the establishment of a larger collection of studied plant proteins taking these UPS pathways, a clearer picture of endomembrane trafficking as a whole will emerge. There are several novel enabling technologies, such as vesicle proteomics and chemical genomics, with great potential for dissecting secretion pathways, providing information about the cargo that travels along them and the conditions that induce them.
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Affiliation(s)
- Destiny J Davis
- Department of Plant Sciences, University of California, Asmundson Hall, One Shields Avenue, Davis, CA, 95616, USA
| | - Byung-Ho Kang
- Center for Organelle Biogenesis and Function, School of Life Sciences, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Angelo S Heringer
- Department of Plant Sciences, University of California, Asmundson Hall, One Shields Avenue, Davis, CA, 95616, USA
| | - Thomas E Wilkop
- Department of Plant Sciences, University of California, Asmundson Hall, One Shields Avenue, Davis, CA, 95616, USA.
| | - Georgia Drakakaki
- Department of Plant Sciences, University of California, Asmundson Hall, One Shields Avenue, Davis, CA, 95616, USA.
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74
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Robinson DG, Ding Y, Jiang L. Unconventional protein secretion in plants: a critical assessment. PROTOPLASMA 2016; 253:31-43. [PMID: 26410830 DOI: 10.1007/s00709-015-0887-1] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 09/18/2015] [Indexed: 05/27/2023]
Abstract
Unconventional protein secretion (UPS) is a collective term for mechanisms by which cytosolic proteins that lack a signal peptide ("leaderless secretory proteins" (LSPs)) can gain access to the cell exterior. Numerous examples of UPS have been well documented in animal and yeast cells. In contrast, our understanding of the mechanism(s) and function of UPS in plants is very limited. This review evaluates the available literature on this subject. The apparent large numbers of LSPs in the plant secretome suggest that UPS also occurs in plants but is not a proof. Although the direct transport of LSPs across the plant plasma membrane (PM) has not yet been described, it is possible that as in other eukaryotes, exosomes may be released from plant cells through fusion of multivesicular bodies (MVBs) with the PM. In this way, LSPs, but also small RNAs (sRNAs), that are passively taken up from the cytosol into the intraluminal vesicles of MVBs, could reach the apoplast. Another possible mechanism is the recently discovered exocyst-positive organelle (EXPO), a double-membrane-bound compartment, distinct from autophagosomes, which appears to sequester LSPs.
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Affiliation(s)
- David G Robinson
- Centre for Organismal Studies, University of Heidelberg, Im Neuenheimer Feld 230, D-69120, Heidelberg, Germany.
| | - Yu Ding
- Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Liwen Jiang
- Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
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75
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Disruption of OsEXO70A1 Causes Irregular Vascular Bundles and Perturbs Mineral Nutrient Assimilation in Rice. Sci Rep 2015; 5:18609. [PMID: 26691393 PMCID: PMC4686888 DOI: 10.1038/srep18609] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 11/23/2015] [Indexed: 11/08/2022] Open
Abstract
Normal uptake, transportation, and assimilation of primary nutrients are essential to plant growth. Tracheary elements (TEs) are tissues responsible for the transport of water and minerals and characterized by patterned secondary cell wall (SCW) thickening. Exocysts are involved in the regulation of SCW deposition by mediating the targeted transport of materials and enzymes to specific membrane areas. EXO70s are highly duplicated in plants and provide exocysts with functional specificity. In this study, we report the isolation of a rice mutant rapid leaf senescence2 (rls2) that exhibits dwarfism, ferruginous spotted necrotic leaves, decreased hydraulic transport, and disordered primary nutrient assimilation. Histological analysis of rls2-1 mutants has indicated impaired cell expansion, collapsed vascular tissues, and irregular SCW deposition. Map-based cloning has revealed that RLS2 encodes OsEXO70A1, which is one of the 47 members of EXO70s in rice. RLS2 was widely expressed and spatially restricted in vascular bundles. Subcellular localization analysis demonstrated that RLS2 was present on both membrane and nuclear regions. Expression analysis revealed that mutations in rls2 triggers transcriptional fluctuation of orthologous EXO70 genes and affects genes involved in primary nutrient absorption and transport. In brief, our study revealed that RLS2 is required for normal vascular bundle differentiation and primary nutrient assimilation.
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76
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Safavian D, Zayed Y, Indriolo E, Chapman L, Ahmed A, Goring DR. RNA Silencing of Exocyst Genes in the Stigma Impairs the Acceptance of Compatible Pollen in Arabidopsis. PLANT PHYSIOLOGY 2015; 169:2526-38. [PMID: 26443677 PMCID: PMC4677879 DOI: 10.1104/pp.15.00635] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 10/06/2015] [Indexed: 05/19/2023]
Abstract
Initial pollen-pistil interactions in the Brassicaceae are regulated by rapid communication between pollen grains and stigmatic papillae and are fundamentally important, as they are the first step toward successful fertilization. The goal of this study was to examine the requirement of exocyst subunits, which function in docking secretory vesicles to sites of polarized secretion, in the context of pollen-pistil interactions. One of the exocyst subunit genes, EXO70A1, was previously identified as an essential factor in the stigma for the acceptance of compatible pollen in Arabidopsis (Arabidopsis thaliana) and Brassica napus. We hypothesized that EXO70A1, along with other exocyst subunits, functions in the Brassicaceae dry stigma to deliver cargo-bearing secretory vesicles to the stigmatic papillar plasma membrane, under the pollen attachment site, for pollen hydration and pollen tube entry. Here, we investigated the functions of exocyst complex genes encoding the remaining seven subunits, SECRETORY3 (SEC3), SEC5, SEC6, SEC8, SEC10, SEC15, and EXO84, in Arabidopsis stigmas following compatible pollinations. Stigma-specific RNA-silencing constructs were used to suppress the expression of each exocyst subunit individually. The early postpollination stages of pollen grain adhesion, pollen hydration, pollen tube penetration, seed set, and overall fertility were analyzed in the transgenic lines to evaluate the requirement of each exocyst subunit. Our findings provide comprehensive evidence that all eight exocyst subunits are necessary in the stigma for the acceptance of compatible pollen. Thus, this work implicates a fully functional exocyst complex as a component of the compatible pollen response pathway to promote pollen acceptance.
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Affiliation(s)
- Darya Safavian
- Department of Cell and Systems Biology and Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, Ontario, Canada M5S 3B2
| | - Yara Zayed
- Department of Cell and Systems Biology and Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, Ontario, Canada M5S 3B2
| | - Emily Indriolo
- Department of Cell and Systems Biology and Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, Ontario, Canada M5S 3B2
| | - Laura Chapman
- Department of Cell and Systems Biology and Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, Ontario, Canada M5S 3B2
| | - Abdalla Ahmed
- Department of Cell and Systems Biology and Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, Ontario, Canada M5S 3B2
| | - Daphne R Goring
- Department of Cell and Systems Biology and Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, Ontario, Canada M5S 3B2
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77
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Lin Y, Ding Y, Wang J, Shen J, Kung CH, Zhuang X, Cui Y, Yin Z, Xia Y, Lin H, Robinson DG, Jiang L. Exocyst-Positive Organelles and Autophagosomes Are Distinct Organelles in Plants. PLANT PHYSIOLOGY 2015; 169:1917-32. [PMID: 26358417 PMCID: PMC4634068 DOI: 10.1104/pp.15.00953] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 09/09/2015] [Indexed: 05/23/2023]
Abstract
Autophagosomes are organelles that deliver cytosolic proteins for degradation in the vacuole of the cell. In contrast, exocyst-positive organelles (EXPO) deliver cytosolic proteins to the cell surface and therefore represent a form of unconventional protein secretion. Because both structures have two boundary membranes, it has been suggested that they may have been falsely treated as separate entities. Using suspension culture cells and root tissue cells of transgenic Arabidopsis (Arabidopsis thaliana) plants expressing either the EXPO marker Arabidopsis Exo70E2-GFP or the autophagosome marker yellow fluorescent protein (YFP)-autophagy-related gene 8e/f (ATG8e/f), and using specific antibodies against Exo70E2 and ATG8, we have now established that, in normally growing cells, EXPO and autophagosomes are distinct from one another. However, when cells/roots are subjected to autophagy induction, EXPO as well as autophagosomes fuse with the vacuole. In the presence of concanamycin A, the punctate fluorescent signals from both organelles inside the vacuole remain visible for hours and overlap to a significant degree. Tonoplast staining with FM4-64/YFP-Rab7-like GTPase/YFP-vesicle-associated membrane protein711 confirmed the internalization of tonoplast membrane concomitant with the sequestration of EXPO and autophagosomes. This suggests that EXPO and autophagosomes may be related to one another; however, whereas induction of autophagy led to an increase in the amount of ATG8 recruited to membranes, Exo70E2 did not respond in a similar manner.
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Affiliation(s)
- Youshun Lin
- Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.L., Y.D., J.W., J.S., C.H.K., X.Z., Y.C., L.J.);CUHK Shenzhen Research Institute, Chinese University of Hong Kong, Shenzhen 518057, China (L.J.);Department of Biology, Hong Kong Baptist University, Hong Kong, China (Z.Y., Y.X.);Partner State Key Laboratory of Agrobiotechnology, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.X.);National Key Laboratory of Plant Molecular Genetics and National Center for Plant Gene Research (Shanghai), Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China (H.L.); andCentre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany (D.G.R.)
| | - Yu Ding
- Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.L., Y.D., J.W., J.S., C.H.K., X.Z., Y.C., L.J.);CUHK Shenzhen Research Institute, Chinese University of Hong Kong, Shenzhen 518057, China (L.J.);Department of Biology, Hong Kong Baptist University, Hong Kong, China (Z.Y., Y.X.);Partner State Key Laboratory of Agrobiotechnology, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.X.);National Key Laboratory of Plant Molecular Genetics and National Center for Plant Gene Research (Shanghai), Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China (H.L.); andCentre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany (D.G.R.)
| | - Juan Wang
- Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.L., Y.D., J.W., J.S., C.H.K., X.Z., Y.C., L.J.);CUHK Shenzhen Research Institute, Chinese University of Hong Kong, Shenzhen 518057, China (L.J.);Department of Biology, Hong Kong Baptist University, Hong Kong, China (Z.Y., Y.X.);Partner State Key Laboratory of Agrobiotechnology, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.X.);National Key Laboratory of Plant Molecular Genetics and National Center for Plant Gene Research (Shanghai), Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China (H.L.); andCentre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany (D.G.R.)
| | - Jinbo Shen
- Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.L., Y.D., J.W., J.S., C.H.K., X.Z., Y.C., L.J.);CUHK Shenzhen Research Institute, Chinese University of Hong Kong, Shenzhen 518057, China (L.J.);Department of Biology, Hong Kong Baptist University, Hong Kong, China (Z.Y., Y.X.);Partner State Key Laboratory of Agrobiotechnology, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.X.);National Key Laboratory of Plant Molecular Genetics and National Center for Plant Gene Research (Shanghai), Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China (H.L.); andCentre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany (D.G.R.)
| | - Chun Hong Kung
- Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.L., Y.D., J.W., J.S., C.H.K., X.Z., Y.C., L.J.);CUHK Shenzhen Research Institute, Chinese University of Hong Kong, Shenzhen 518057, China (L.J.);Department of Biology, Hong Kong Baptist University, Hong Kong, China (Z.Y., Y.X.);Partner State Key Laboratory of Agrobiotechnology, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.X.);National Key Laboratory of Plant Molecular Genetics and National Center for Plant Gene Research (Shanghai), Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China (H.L.); andCentre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany (D.G.R.)
| | - Xiaohong Zhuang
- Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.L., Y.D., J.W., J.S., C.H.K., X.Z., Y.C., L.J.);CUHK Shenzhen Research Institute, Chinese University of Hong Kong, Shenzhen 518057, China (L.J.);Department of Biology, Hong Kong Baptist University, Hong Kong, China (Z.Y., Y.X.);Partner State Key Laboratory of Agrobiotechnology, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.X.);National Key Laboratory of Plant Molecular Genetics and National Center for Plant Gene Research (Shanghai), Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China (H.L.); andCentre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany (D.G.R.)
| | - Yong Cui
- Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.L., Y.D., J.W., J.S., C.H.K., X.Z., Y.C., L.J.);CUHK Shenzhen Research Institute, Chinese University of Hong Kong, Shenzhen 518057, China (L.J.);Department of Biology, Hong Kong Baptist University, Hong Kong, China (Z.Y., Y.X.);Partner State Key Laboratory of Agrobiotechnology, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.X.);National Key Laboratory of Plant Molecular Genetics and National Center for Plant Gene Research (Shanghai), Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China (H.L.); andCentre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany (D.G.R.)
| | - Zhao Yin
- Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.L., Y.D., J.W., J.S., C.H.K., X.Z., Y.C., L.J.);CUHK Shenzhen Research Institute, Chinese University of Hong Kong, Shenzhen 518057, China (L.J.);Department of Biology, Hong Kong Baptist University, Hong Kong, China (Z.Y., Y.X.);Partner State Key Laboratory of Agrobiotechnology, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.X.);National Key Laboratory of Plant Molecular Genetics and National Center for Plant Gene Research (Shanghai), Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China (H.L.); andCentre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany (D.G.R.)
| | - Yiji Xia
- Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.L., Y.D., J.W., J.S., C.H.K., X.Z., Y.C., L.J.);CUHK Shenzhen Research Institute, Chinese University of Hong Kong, Shenzhen 518057, China (L.J.);Department of Biology, Hong Kong Baptist University, Hong Kong, China (Z.Y., Y.X.);Partner State Key Laboratory of Agrobiotechnology, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.X.);National Key Laboratory of Plant Molecular Genetics and National Center for Plant Gene Research (Shanghai), Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China (H.L.); andCentre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany (D.G.R.)
| | - Hongxuan Lin
- Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.L., Y.D., J.W., J.S., C.H.K., X.Z., Y.C., L.J.);CUHK Shenzhen Research Institute, Chinese University of Hong Kong, Shenzhen 518057, China (L.J.);Department of Biology, Hong Kong Baptist University, Hong Kong, China (Z.Y., Y.X.);Partner State Key Laboratory of Agrobiotechnology, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.X.);National Key Laboratory of Plant Molecular Genetics and National Center for Plant Gene Research (Shanghai), Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China (H.L.); andCentre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany (D.G.R.)
| | - David G Robinson
- Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.L., Y.D., J.W., J.S., C.H.K., X.Z., Y.C., L.J.);CUHK Shenzhen Research Institute, Chinese University of Hong Kong, Shenzhen 518057, China (L.J.);Department of Biology, Hong Kong Baptist University, Hong Kong, China (Z.Y., Y.X.);Partner State Key Laboratory of Agrobiotechnology, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.X.);National Key Laboratory of Plant Molecular Genetics and National Center for Plant Gene Research (Shanghai), Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China (H.L.); andCentre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany (D.G.R.)
| | - Liwen Jiang
- Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.L., Y.D., J.W., J.S., C.H.K., X.Z., Y.C., L.J.);CUHK Shenzhen Research Institute, Chinese University of Hong Kong, Shenzhen 518057, China (L.J.);Department of Biology, Hong Kong Baptist University, Hong Kong, China (Z.Y., Y.X.);Partner State Key Laboratory of Agrobiotechnology, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.X.);National Key Laboratory of Plant Molecular Genetics and National Center for Plant Gene Research (Shanghai), Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China (H.L.); andCentre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany (D.G.R.)
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Fujisaki K, Abe Y, Ito A, Saitoh H, Yoshida K, Kanzaki H, Kanzaki E, Utsushi H, Yamashita T, Kamoun S, Terauchi R. Rice Exo70 interacts with a fungal effector, AVR-Pii, and is required for AVR-Pii-triggered immunity. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2015; 83:875-87. [PMID: 26186703 DOI: 10.1111/tpj.12934] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Revised: 06/26/2015] [Accepted: 06/26/2015] [Indexed: 05/03/2023]
Abstract
Vesicle trafficking including the exocytosis pathway is intimately associated with host immunity against pathogens. However, we still have insufficient knowledge about how it contributes to immunity, and how pathogen factors affect it. In this study, we explore host factors that interact with the Magnaporthe oryzae effector AVR-Pii. Gel filtration chromatography and co-immunoprecipitation assays identified a 150 kDa complex of proteins in the soluble fraction comprising AVR-Pii and OsExo70-F2 and OsExo70-F3, two rice Exo70 proteins presumably involved in exocytosis. Simultaneous knockdown of OsExo70-F2 and F3 totally abrogated Pii immune receptor-dependent resistance, but had no effect on Pia- and Pik-dependent resistance. Knockdown levels of OsExo70-F3 but not OsExo70-F2 correlated with reduction of Pii function, suggesting that OsExo70-F3 is specifically involved in Pii-dependent resistance. Under our current experimental conditions, over-expression of AVR-Pii or knockdown of OsExo70-F2 and -F3 genes in rice did not affect the virulence of compatible isolates of M. oryzae. AVR-Pii interaction with OsExo70-F3 appears to play a crucial role in immunity triggered by Pii, suggesting a role for OsExo70 as a decoy or helper in Pii/AVR-Pii interactions.
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Affiliation(s)
- Koki Fujisaki
- Iwate Biotechnology Research Center, Kitakami, Iwate, Japan
| | - Yoshiko Abe
- Iwate Biotechnology Research Center, Kitakami, Iwate, Japan
| | - Akiko Ito
- Iwate Biotechnology Research Center, Kitakami, Iwate, Japan
| | | | - Kentaro Yoshida
- Organization of Advanced Science and Technology, Kobe University, Kobe, Hyogo, Japan
| | | | - Eiko Kanzaki
- Iwate Biotechnology Research Center, Kitakami, Iwate, Japan
| | - Hiroe Utsushi
- Iwate Biotechnology Research Center, Kitakami, Iwate, Japan
| | | | - Sophien Kamoun
- The Sainsbury Laboratory, Norwich Research Park, Norwich, UK
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79
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New Insight into the Mechanism and Function of Autophagy in Plant Cells. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 320:1-40. [PMID: 26614870 DOI: 10.1016/bs.ircmb.2015.07.005] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Autophagy is a degradation pathway that is conserved throughout eukaryotic organisms and plays important roles in the tolerance of abiotic and biotic stresses. It functions as a housekeeping process to remove unwanted cell components under normal conditions, and is induced during stress and senescence to break down damaged cellular contents and to recycle materials. The target components are engulfed into specialized transport structures termed autophagosomes and are subsequently delivered to the vacuole for degradation. Here, we review milestones in the study of autophagy in plants, discuss recent advances in our understanding of the mechanism and physiological roles of plant autophagy, and highlight potential future directions of research.
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80
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Abstract
The exocyst is an octameric protein complex that is implicated in the tethering of secretory vesicles to the plasma membrane prior to SNARE-mediated fusion. Spatial and temporal control of exocytosis through the exocyst has a crucial role in a number of physiological processes, such as morphogenesis, cell cycle progression, primary ciliogenesis, cell migration and tumor invasion. In this Cell Science at a Glance poster article, we summarize recent works on the molecular organization, function and regulation of the exocyst complex, as they provide rationales to the involvement of this complex in such a diverse array of cellular processes.
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Affiliation(s)
- Bin Wu
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Wei Guo
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
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81
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Handa Y, Nishide H, Takeda N, Suzuki Y, Kawaguchi M, Saito K. RNA-seq Transcriptional Profiling of an Arbuscular Mycorrhiza Provides Insights into Regulated and Coordinated Gene Expression in Lotus japonicus and Rhizophagus irregularis. PLANT & CELL PHYSIOLOGY 2015; 56:1490-511. [PMID: 26009592 DOI: 10.1093/pcp/pcv071] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 05/13/2015] [Indexed: 05/03/2023]
Abstract
Gene expression during arbuscular mycorrhizal development is highly orchestrated in both plants and arbuscular mycorrhizal fungi. To elucidate the gene expression profiles of the symbiotic association, we performed a digital gene expression analysis of Lotus japonicus and Rhizophagus irregularis using a HiSeq 2000 next-generation sequencer with a Cufflinks assembly and de novo transcriptome assembly. There were 3,641 genes differentially expressed during arbuscular mycorrhizal development in L. japonicus, approximately 80% of which were up-regulated. The up-regulated genes included secreted proteins, transporters, proteins involved in lipid and amino acid metabolism, ribosomes and histones. We also detected many genes that were differentially expressed in small-secreted peptides and transcription factors, which may be involved in signal transduction or transcription regulation during symbiosis. Co-regulated genes between arbuscular mycorrhizal and root nodule symbiosis were not particularly abundant, but transcripts encoding for membrane traffic-related proteins, transporters and iron transport-related proteins were found to be highly co-up-regulated. In transcripts of arbuscular mycorrhizal fungi, expansion of cytochrome P450 was observed, which may contribute to various metabolic pathways required to accommodate roots and soil. The comprehensive gene expression data of both plants and arbuscular mycorrhizal fungi provide a powerful platform for investigating the functional and molecular mechanisms underlying arbuscular mycorrhizal symbiosis.
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Affiliation(s)
- Yoshihiro Handa
- Division of Symbiotic Systems, National Institute for Basic Biology, Okazaki, Aichi 444-8585, Japan
| | - Hiroyo Nishide
- Data Integration and Analysis Facility, National Institute for Basic Biology, Okazaki, Aichi 444-8585, Japan
| | - Naoya Takeda
- Division of Symbiotic Systems, National Institute for Basic Biology, Okazaki, Aichi 444-8585, Japan School of Life Science, SOKENDAI (Graduate University for Advanced Studies), Okazaki, Aichi 444-8585, Japan
| | - Yutaka Suzuki
- Department of Medical Genome Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba 277-8561, Japan
| | - Masayoshi Kawaguchi
- Division of Symbiotic Systems, National Institute for Basic Biology, Okazaki, Aichi 444-8585, Japan School of Life Science, SOKENDAI (Graduate University for Advanced Studies), Okazaki, Aichi 444-8585, Japan
| | - Katsuharu Saito
- Faculty of Agriculture, Shinshu University, Minamiminowa, Nagano 399-4598, Japan
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82
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Zhao Q, Gao C, Lee P, Liu L, Li S, Hu T, Shen J, Pan S, Ye H, Chen Y, Cao W, Cui Y, Zeng P, Yu S, Gao Y, Chen L, Mo B, Liu X, Xiao S, Zhao Y, Zhong S, Chen X, Jiang L. Fast-suppressor screening for new components in protein trafficking, organelle biogenesis and silencing pathway in Arabidopsis thaliana using DEX-inducible FREE1-RNAi plants. J Genet Genomics 2015; 42:319-30. [PMID: 26165498 DOI: 10.1016/j.jgg.2015.03.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Revised: 03/21/2015] [Accepted: 03/27/2015] [Indexed: 12/20/2022]
Abstract
Membrane trafficking is essential for plant growth and responses to external signals. The plant unique FYVE domain-containing protein FREE1 is a component of the ESCRT complex (endosomal sorting complex required for transport). FREE1 plays multiple roles in regulating protein trafficking and organelle biogenesis including the formation of intraluminal vesicles of multivesicular body (MVB), vacuolar protein transport and vacuole biogenesis, and autophagic degradation. FREE1 knockout plants show defective MVB formation, abnormal vacuolar transport, fragmented vacuoles, accumulated autophagosomes, and seedling lethality. To further uncover the underlying mechanisms of FREE1 function in plants, we performed a forward genetic screen for mutants that suppressed the seedling lethal phenotype of FREE1-RNAi transgenic plants. The obtained mutants are termed as suppressors of free1 (sof). To date, 229 putative sof mutants have been identified. Barely detecting of FREE1 protein with M3 plants further identified 84 FREE1-related suppressors. Also 145 mutants showing no reduction of FREE1 protein were termed as RNAi-related mutants. Through next-generation sequencing (NGS) of bulked DNA from F2 mapping population of two RNAi-related sof mutants, FREE1-RNAi T-DNA inserted on chromosome 1 was identified and the causal mutation of putative sof mutant is being identified similarly. These FREE1- and RNAi-related sof mutants will be useful tools and resources for illustrating the underlying mechanisms of FREE1 function in intracellular trafficking and organelle biogenesis, as well as for uncovering the new components involved in the regulation of silencing pathways in plants.
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Affiliation(s)
- Qiong Zhao
- Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Caiji Gao
- Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - PoShing Lee
- Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Lin Liu
- Department of Botany and Plant Sciences, Institute of Integrative Genome Biology, University of California, Riverside, CA 92521, USA
| | - Shaofang Li
- Department of Botany and Plant Sciences, Institute of Integrative Genome Biology, University of California, Riverside, CA 92521, USA
| | - Tangjin Hu
- CUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen 518057, China
| | - Jinbo Shen
- Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Shuying Pan
- CUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen 518057, China
| | - Hao Ye
- CUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen 518057, China
| | - Yunru Chen
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Wenhan Cao
- Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Yong Cui
- Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Peng Zeng
- Beijing Genomics Institute at Shenzhen, Shenzhen 518083, China
| | - Sheng Yu
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Yangbin Gao
- Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, USA
| | - Liang Chen
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Beixin Mo
- Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences, Shenzhen University, Shenzhen 518060, China
| | - Xin Liu
- Beijing Genomics Institute at Shenzhen, Shenzhen 518083, China
| | - Shi Xiao
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Yunde Zhao
- Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, USA
| | - Silin Zhong
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Xuemei Chen
- Department of Botany and Plant Sciences, Institute of Integrative Genome Biology, University of California, Riverside, CA 92521, USA
| | - Liwen Jiang
- Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China; CUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen 518057, China.
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83
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Kulich I, Vojtíková Z, Glanc M, Ortmannová J, Rasmann S, Žárský V. Cell wall maturation of Arabidopsis trichomes is dependent on exocyst subunit EXO70H4 and involves callose deposition. PLANT PHYSIOLOGY 2015; 168:120-31. [PMID: 25767057 PMCID: PMC4424025 DOI: 10.1104/pp.15.00112] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2015] [Accepted: 03/10/2015] [Indexed: 05/22/2023]
Abstract
Arabidopsis (Arabidopsis thaliana) leaf trichomes are single-cell structures with a well-studied development, but little is understood about their function. Developmental studies focused mainly on the early shaping stages, and little attention has been paid to the maturation stage. We focused on the EXO70H4 exocyst subunit, one of the most up-regulated genes in the mature trichome. We uncovered EXO70H4-dependent development of the secondary cell wall layer, highly autofluorescent and callose rich, deposited only in the upper part of the trichome. The boundary is formed between the apical and the basal parts of mature trichome by a callose ring that is also deposited in an EXO70H4-dependent manner. We call this structure the Ortmannian ring (OR). Both the secondary cell wall layer and the OR are absent in the exo70H4 mutants. Ecophysiological aspects of the trichome cell wall thickening include interference with antiherbivore defense and heavy metal accumulation. Ultraviolet B light induces EXO70H4 transcription in a CONSTITUTIVE PHOTOMORPHOGENIC1-dependent way, resulting in stimulation of trichome cell wall thickening and the OR biogenesis. EXO70H4-dependent trichome cell wall hardening is a unique phenomenon, which may be conserved among a variety of the land plants. Our analyses support a concept that Arabidopsis trichome is an excellent model to study molecular mechanisms of secondary cell wall deposition.
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Affiliation(s)
- Ivan Kulich
- Department of Experimental Plant Biology, Faculty of Sciences, Charles University, 12844 Prague, Czech Republic (I.K., Z.V., M.G., J.O., V.Z.);Institute of Experimental Botany, Academy of Sciences of the Czech Republic, 16502 Prague, Czech Republic (J.O., V.Z.); andDepartment of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland (S.R.)
| | - Zdeňka Vojtíková
- Department of Experimental Plant Biology, Faculty of Sciences, Charles University, 12844 Prague, Czech Republic (I.K., Z.V., M.G., J.O., V.Z.);Institute of Experimental Botany, Academy of Sciences of the Czech Republic, 16502 Prague, Czech Republic (J.O., V.Z.); andDepartment of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland (S.R.)
| | - Matouš Glanc
- Department of Experimental Plant Biology, Faculty of Sciences, Charles University, 12844 Prague, Czech Republic (I.K., Z.V., M.G., J.O., V.Z.);Institute of Experimental Botany, Academy of Sciences of the Czech Republic, 16502 Prague, Czech Republic (J.O., V.Z.); andDepartment of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland (S.R.)
| | - Jitka Ortmannová
- Department of Experimental Plant Biology, Faculty of Sciences, Charles University, 12844 Prague, Czech Republic (I.K., Z.V., M.G., J.O., V.Z.);Institute of Experimental Botany, Academy of Sciences of the Czech Republic, 16502 Prague, Czech Republic (J.O., V.Z.); andDepartment of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland (S.R.)
| | - Sergio Rasmann
- Department of Experimental Plant Biology, Faculty of Sciences, Charles University, 12844 Prague, Czech Republic (I.K., Z.V., M.G., J.O., V.Z.);Institute of Experimental Botany, Academy of Sciences of the Czech Republic, 16502 Prague, Czech Republic (J.O., V.Z.); andDepartment of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland (S.R.)
| | - Viktor Žárský
- Department of Experimental Plant Biology, Faculty of Sciences, Charles University, 12844 Prague, Czech Republic (I.K., Z.V., M.G., J.O., V.Z.);Institute of Experimental Botany, Academy of Sciences of the Czech Republic, 16502 Prague, Czech Republic (J.O., V.Z.); andDepartment of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland (S.R.)
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84
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Onelli E, Idilli AI, Moscatelli A. Emerging roles for microtubules in angiosperm pollen tube growth highlight new research cues. FRONTIERS IN PLANT SCIENCE 2015; 6:51. [PMID: 25713579 PMCID: PMC4322846 DOI: 10.3389/fpls.2015.00051] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Accepted: 01/20/2015] [Indexed: 05/21/2023]
Abstract
In plants, actin filaments have an important role in organelle movement and cytoplasmic streaming. Otherwise microtubules (MTs) have a role in restricting organelles to specific areas of the cell and in maintaining organelle morphology. In somatic plant cells, MTs also participate in cell division and morphogenesis, allowing cells to take their definitive shape in order to perform specific functions. In the latter case, MTs influence assembly of the cell wall, controlling the delivery of enzymes involved in cellulose synthesis and of wall modulation material to the proper sites. In angiosperm pollen tubes, organelle movement is generally attributed to the acto-myosin system, the main role of which is in distributing organelles in the cytoplasm and in carrying secretory vesicles to the apex for polarized growth. Recent data on membrane trafficking suggests a role of MTs in fine delivery and repositioning of vesicles to sustain pollen tube growth. This review examines the role of MTs in secretion and endocytosis, highlighting new research cues regarding cell wall construction and pollen tube-pistil crosstalk, that help unravel the role of MTs in polarized growth.
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Affiliation(s)
| | - Aurora I. Idilli
- Institute of Biophysics, National Research Council and Fondazione Bruno Kessler, Trento, Italy
| | - Alessandra Moscatelli
- Department of Biosciences, University of Milan, Milan, Italy
- *Correspondence: Alessandra Moscatelli, Department of Biosciences, University of Milan, Via Celoria, 26, 20113 Milano, Italy e-mail:
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85
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Cole RA, McInally SA, Fowler JE. Developmentally distinct activities of the exocyst enable rapid cell elongation and determine meristem size during primary root growth in Arabidopsis. BMC PLANT BIOLOGY 2014; 14:386. [PMID: 25551204 PMCID: PMC4302519 DOI: 10.1186/s12870-014-0386-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 12/15/2014] [Indexed: 05/20/2023]
Abstract
BACKGROUND Exocytosis is integral to root growth: trafficking components of systems that control growth (e.g., PIN auxin transport proteins) to the plasma membrane, and secreting materials that expand the cell wall to the apoplast. Spatiotemporal regulation of exocytosis in eukaryotes often involves the exocyst, an octameric complex that tethers selected secretory vesicles to specific sites on the plasma membrane and facilitates their exocytosis. We evaluated Arabidopsis lines with mutations in four exocyst components (SEC5, SEC8, EXO70A1 and EXO84B) to explore exocyst function in primary root growth. RESULTS The mutants have root growth rates that are 82% to 11% of wild-type. Even in lines with the most severe defects, the organization of the quiescent center and tissue layers at the root tips appears similar to wild-type, although meristematic, transition, and elongation zones are shorter. Reduced cell production rates in the mutants are due to the shorter meristems, but not to lengthened cell cycles. Additionally, mutants demonstrate reduced anisotropic cell expansion in the elongation zone, but not the meristematic zone, resulting in shorter mature cells that are similar in shape to wild-type. As expected, hypersensitivity to brefeldin A links the mutant root growth defect to altered vesicular trafficking. Several experimental approaches (e.g., dose-response measurements, localization of signaling components) failed to identify aberrant auxin or brassinosteroid signaling as a primary driver for reduced root growth in exocyst mutants. CONCLUSIONS The exocyst participates in two spatially distinct developmental processes, apparently by mechanisms not directly linked to auxin or brassinosteroid signaling pathways, to help establish root meristem size, and to facilitate rapid cell expansion in the elongation zone.
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Affiliation(s)
- Rex A Cole
- Botany and Plant Pathology, Oregon State University, 2082 Cordley Hall, Corvallis, 97331 OR USA
| | - Samantha A McInally
- Botany and Plant Pathology, Oregon State University, 2082 Cordley Hall, Corvallis, 97331 OR USA
| | - John E Fowler
- Botany and Plant Pathology, Oregon State University, 2082 Cordley Hall, Corvallis, 97331 OR USA
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86
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Ding Y, Robinson DG, Jiang L. Unconventional protein secretion (UPS) pathways in plants. Curr Opin Cell Biol 2014; 29:107-15. [PMID: 24949560 DOI: 10.1016/j.ceb.2014.05.008] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Revised: 04/09/2014] [Accepted: 05/22/2014] [Indexed: 02/09/2023]
Abstract
As in yeast and mammalian cells, novel unconventional protein secretion (UPS) or unconventional membrane trafficking pathways are now known to operate in plants. UPS in plants is generally associated with stress conditions such as pathogen attack, but little is known about its underlying mechanism and function. Here, we present an update on the current knowledge of UPS in the plants in terms of its transport pathways, possible functions and its relationship to autophagy.
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Affiliation(s)
- Yu Ding
- School of Life Sciences, Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - David G Robinson
- Centre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany
| | - Liwen Jiang
- School of Life Sciences, Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China; Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen 518057, China.
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87
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Vukašinović N, Cvrčková F, Eliáš M, Cole R, Fowler JE, Žárský V, Synek L. Dissecting a hidden gene duplication: the Arabidopsis thaliana SEC10 locus. PLoS One 2014; 9:e94077. [PMID: 24728280 PMCID: PMC3984084 DOI: 10.1371/journal.pone.0094077] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Accepted: 03/11/2014] [Indexed: 01/01/2023] Open
Abstract
Repetitive sequences present a challenge for genome sequence assembly, and highly similar segmental duplications may disappear from assembled genome sequences. Having found a surprising lack of observable phenotypic deviations and non-Mendelian segregation in Arabidopsis thaliana mutants in SEC10, a gene encoding a core subunit of the exocyst tethering complex, we examined whether this could be explained by a hidden gene duplication. Re-sequencing and manual assembly of the Arabidopsis thaliana SEC10 (At5g12370) locus revealed that this locus, comprising a single gene in the reference genome assembly, indeed contains two paralogous genes in tandem, SEC10a and SEC10b, and that a sequence segment of 7 kb in length is missing from the reference genome sequence. Differences between the two paralogs are concentrated in non-coding regions, while the predicted protein sequences exhibit 99% identity, differing only by substitution of five amino acid residues and an indel of four residues. Both SEC10 genes are expressed, although varying transcript levels suggest differential regulation. Homozygous T-DNA insertion mutants in either paralog exhibit a wild-type phenotype, consistent with proposed extensive functional redundancy of the two genes. By these observations we demonstrate that recently duplicated genes may remain hidden even in well-characterized genomes, such as that of A. thaliana. Moreover, we show that the use of the existing A. thaliana reference genome sequence as a guide for sequence assembly of new Arabidopsis accessions or related species has at least in some cases led to error propagation.
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Affiliation(s)
- Nemanja Vukašinović
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Prague, Czech Republic
- Department of Experimental Plant Biology, Faculty of Science, Charles University in Prague, Prague, Czech Republic
| | - Fatima Cvrčková
- Department of Experimental Plant Biology, Faculty of Science, Charles University in Prague, Prague, Czech Republic
| | - Marek Eliáš
- Department of Botany, Faculty of Science, Charles University in Prague, Prague, Czech Republic
- Department of Biology and Ecology, Faculty of Science, University of Ostrava, Ostrava, Czech Republic
| | - Rex Cole
- Department of Botany and Plant Pathology and Center for Genome Research and Biocomputing, Oregon State University, Corvallis, Oregon, United States of America
| | - John E. Fowler
- Department of Botany and Plant Pathology and Center for Genome Research and Biocomputing, Oregon State University, Corvallis, Oregon, United States of America
| | - Viktor Žárský
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Prague, Czech Republic
- Department of Experimental Plant Biology, Faculty of Science, Charles University in Prague, Prague, Czech Republic
| | - Lukáš Synek
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Prague, Czech Republic
- * E-mail:
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88
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Exo70 isoform switching upon epithelial-mesenchymal transition mediates cancer cell invasion. Dev Cell 2014; 27:560-73. [PMID: 24331928 DOI: 10.1016/j.devcel.2013.10.020] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Revised: 07/31/2013] [Accepted: 10/28/2013] [Indexed: 02/06/2023]
Abstract
Epithelial-mesenchymal transition (EMT) is an important developmental process hijacked by cancer cells for their dissemination. Here, we show that Exo70, a component of the exocyst complex, undergoes isoform switching mediated by ESRP1, a pre-mRNA splicing factor that regulates EMT. Expression of the epithelial isoform of Exo70 affects the levels of key EMT transcriptional regulators such as Snail and ZEB2 and is sufficient to drive the transition to epithelial phenotypes. Differential Exo70 isoform expression in human tumors correlates with cancer progression, and increased expression of the epithelial isoform of Exo70 inhibits tumor metastasis in mice. At the molecular level, the mesenchymal-but not the epithelial-isoform of Exo70 interacts with the Arp2/3 complex and stimulates actin polymerization for tumor invasion. Our findings provide a mechanism by which the exocyst function and actin dynamics are modulated for EMT and tumor invasion.
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89
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Synek L, Sekereš J, Žárský V. The exocyst at the interface between cytoskeleton and membranes in eukaryotic cells. FRONTIERS IN PLANT SCIENCE 2014; 4:543. [PMID: 24427163 PMCID: PMC3877765 DOI: 10.3389/fpls.2013.00543] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Accepted: 12/12/2013] [Indexed: 05/07/2023]
Abstract
Delivery and final fusion of the secretory vesicles with the relevant target membrane are hierarchically organized and reciprocally interconnected multi-step processes involving not only specific protein-protein interactions, but also specific protein-phospholipid interactions. The exocyst was discovered as a tethering complex mediating initial encounter of arriving exocytic vesicles with the plasma membrane. The exocyst complex is regulated by Rab and Rho small GTPases, resulting in docking of exocytic vesicles to the plasma membrane (PM) and finally their fusion mediated by specific SNARE complexes. In model Opisthokont cells, the exocyst was shown to directly interact with both microtubule and microfilament cytoskeleton and related motor proteins as well as with the PM via phosphatidylinositol 4, 5-bisphosphate specific binding, which directly affects cortical cytoskeleton and PM dynamics. Here we summarize the current knowledge on exocyst-cytoskeleton-PM interactions in order to open a perspective for future research in this area in plant cells.
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Affiliation(s)
- Lukáš Synek
- Laboratory of Cell Biology, Institute of Experimental Botany, Academy of Sciences of the Czech RepublicPrague, Czech Republic
| | - Juraj Sekereš
- Laboratory of Cell Biology, Institute of Experimental Botany, Academy of Sciences of the Czech RepublicPrague, Czech Republic
- Laboratory of Plant Cell Biology, Department of Experimental Plant Biology, Faculty of Science, Charles University in PraguePrague, Czech Republic
| | - Viktor Žárský
- Laboratory of Cell Biology, Institute of Experimental Botany, Academy of Sciences of the Czech RepublicPrague, Czech Republic
- Laboratory of Plant Cell Biology, Department of Experimental Plant Biology, Faculty of Science, Charles University in PraguePrague, Czech Republic
- *Correspondence: Viktor Žárský, Laboratory of Plant Cell Biology, Department of Experimental Plant Biology, Faculty of Science, Charles University in Prague, Vinicna 5, 12844 Prague, Czech Republic e-mail:
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90
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Ding Y, Wang J, Chun Lai JH, Ling Chan VH, Wang X, Cai Y, Tan X, Bao Y, Xia J, Robinson DG, Jiang L. Exo70E2 is essential for exocyst subunit recruitment and EXPO formation in both plants and animals. Mol Biol Cell 2013; 25:412-26. [PMID: 24307681 PMCID: PMC3907280 DOI: 10.1091/mbc.e13-10-0586] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
In contrast to a single copy of Exo70 in yeast and mammals, the Arabidopsis genome contains 23 paralogues of Exo70 (AtExo70). Using AtExo70E2 and its GFP fusion as probes, we recently identified a novel double-membrane organelle termed exocyst-positive organelle (EXPO) that mediates an unconventional protein secretion in plant cells. Here we further demonstrate that AtExo70E2 is essential for exocyst subunit recruitment and for EXPO formation in both plants and animals. By performing transient expression in Arabidopsis protoplasts, we established that a number of exocyst subunits (especially the members of the Sec family) are unable to be recruited to EXPO in the absence of AtExo70E2. The paralogue AtExo70A1 is unable to substitute for AtExo70E2 in this regard. Fluorescence resonance energy transfer assay and bimolecular fluorescence complementation analyses confirm the interaction between AtExo70E2 and Sec6 and Sec10. AtExo70E2, but not its yeast counterpart, is also capable of inducing EXPO formation in an animal cell line (HEK293A cells). Electron microscopy confirms the presence of double-membraned, EXPO-like structures in HEK293A cells expressing AtExo70E2. Inversely, neither human nor yeast Exo70 homologues cause the formation of EXPO in Arabidopsis protoplasts. These results point to a specific and crucial role for AtExo70E2 in EXPO formation.
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Affiliation(s)
- Yu Ding
- School of Life Sciences, Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China Division of Life Science, Division of Biomedical Engineering and State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China Department of Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany Shenzhen Research Institute, Chinese University of Hong Kong, Shenzhen 518057, China
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91
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Zárský V, Kulich I, Fendrych M, Pečenková T. Exocyst complexes multiple functions in plant cells secretory pathways. CURRENT OPINION IN PLANT BIOLOGY 2013; 16:726-33. [PMID: 24246229 DOI: 10.1016/j.pbi.2013.10.013] [Citation(s) in RCA: 116] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Revised: 10/21/2013] [Accepted: 10/22/2013] [Indexed: 05/18/2023]
Abstract
The exocyst is a complex of proteins mediating first contact (tethering) between secretory vesicles and the target membrane. Discovered in yeast as an effector of RAB and RHO small GTPases, it was also found to function in land plants. Plant cells and tissues rely on targeted exocytosis and this implies that the exocyst is involved in regulation of cell polarity and morphogenesis, including cytokinesis, plasma membrane protein recycling (including PINs, the auxin efflux carriers), cell wall biogenesis, fertilization, stress and biotic interactions including defence against pathogens. The dramatic expansion of the EXO70 subunit gene family, of which individual members are likely responsible for exocyst complex targeting, implies that there are specialized functions of different exocysts with different EXO70s. One of these functions comprises a role in autophagy-related Golgi independent membrane trafficking into the vacuole or apoplast. It is also possible, that some EXO70 paralogues have been recruited into exocyst independent functions. The exocyst has the potential to function as an important regulatory hub to coordinate endomembrane dynamics in plants.
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Affiliation(s)
- Viktor Zárský
- Department of Experimental Plant Biology, Faculty of Sciences, Charles University, Viničná 5, Prague 2, 128 43, Czech Republic; Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Rozvojová 263, Prague 6, 165 02, Czech Republic.
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92
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Cvrčková F. Formins and membranes: anchoring cortical actin to the cell wall and beyond. FRONTIERS IN PLANT SCIENCE 2013; 4:436. [PMID: 24204371 PMCID: PMC3817587 DOI: 10.3389/fpls.2013.00436] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Accepted: 10/13/2013] [Indexed: 05/03/2023]
Abstract
Formins are evolutionarily conserved eukaryotic proteins participating in actin and microtubule organization. Land plants have three formin clades, with only two - Class I and II - present in angiosperms. Class I formins are often transmembrane proteins, residing at the plasmalemma and anchoring the cortical cytoskeleton across the membrane to the cell wall, while Class II formins possess a PTEN-related membrane-binding domain. Lower plant Class III and non-plant formins usually contain domains predicted to bind RHO GTPases that are membrane-associated. Thus, some kind of membrane anchorage appears to be a common formin feature. Direct interactions between various non-plant formins and integral or peripheral membrane proteins have indeed been reported, with varying mechanisms and biological implications. Besides of summarizing new data on Class I and Class II formin-membrane relationships, this review surveys such "non-classical" formin-membrane interactions and examines which, if any, of them may be evolutionarily conserved and operating also in plants. FYVE, SH3 and BAR domain-containing proteins emerge as possible candidates for such conserved membrane-associated formin partners.
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Affiliation(s)
- Fatima Cvrčková
- *Correspondence: Fatima Cvrčková, Department of Experimental Plant Biology, Faculty of Science, Charles University, Viničná 5, CZ 128 43, Prague, Czech Republic e-mail:
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93
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Cvrčková F, Žárský V. Old AIMs of the exocyst: evidence for an ancestral association of exocyst subunits with autophagy-associated Atg8 proteins. PLANT SIGNALING & BEHAVIOR 2013; 8:e27099. [PMID: 24305598 PMCID: PMC4091244 DOI: 10.4161/psb.27099] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
In a recent addendum, Oren Tzfadia and Gad Galili (PSB 2014; 9:e26732) showed that several Arabidopsis exocyst subunits possess consensus Atg8-interacting motifs (AIMs), which may mediate their interaction with the autophagy-associated Atg8 protein, providing thus a mechanistic base for participation of exocyst (sub)complexes in autophagy. However, the bioinformatically identified AIMs are short peptide motifs that may occur by chance. We thus performed an exhaustive search in a large collection of plant exocyst-derived sequences from our previous bioinformatic study and found that AIMs are over-represented among exocyst subunits of all lineages examined, including moss and club moss, compared with a representative sample of the Arabidopsis proteome. This is consistent with the proposed exocyst AIMs being biologically meaningful and evolutionarily ancient. Moreover, among the numerous EXO70 paralogs, the monocot-specific EXO70F clade appears to be exempt from the general AIM enrichment, suggesting a modification of the autophagy connection in a subset of exocyst variants.
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94
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Li S, Chen M, Yu D, Ren S, Sun S, Liu L, Ketelaar T, Emons AMC, Liu CM. EXO70A1-mediated vesicle trafficking is critical for tracheary element development in Arabidopsis. THE PLANT CELL 2013; 25:1774-86. [PMID: 23709627 PMCID: PMC3694705 DOI: 10.1105/tpc.113.112144] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2013] [Revised: 04/20/2013] [Accepted: 05/14/2013] [Indexed: 05/18/2023]
Abstract
Exocysts are highly conserved octameric complexes that play an essential role in the tethering of Golgi-derived vesicles to target membranes in eukaryotic organisms. Genes encoding the EXO70 subunit are highly duplicated in plants. Based on expression analyses, we proposed previously that individual EXO70 members may provide the exocyst with functional specificity to regulate cell type- or cargo-specific exocytosis, although direct evidence is not available. Here, we show that, as a gene expressed primarily during tracheary element (TE) development, EXO70A1 regulates vesicle trafficking in TE differentiation in Arabidopsis thaliana. Mutations of EXO70A1 led to aberrant xylem development, producing dwarfed and nearly sterile plants with very low fertility, reduced cell expansion, and decreased water potential and hydraulic transport. Grafting of a mutant shoot onto wild-type rootstock rescued most of these aboveground phenotypes, while grafting of a wild-type shoot to the mutant rootstock did not rescue the short root hair phenotype, consistent with the role of TEs in hydraulic transport from roots to shoots. Histological analyses revealed an altered pattern of secondary cell wall thickening and accumulation of large membrane-bound compartments specifically in developing TEs of the mutant. We thus propose that EXO70A1 functions in vesicle trafficking in TEs to regulate patterned secondary cell wall thickening.
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Affiliation(s)
- Shipeng Li
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- Laboratory of Cell Biology, Wageningen University, 6708PB Wageningen, The Netherlands
- Department of Life Science, Qilu Normal University, Jinan 250013, China
| | - Min Chen
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- College of Life Science, Shandong Normal University, Jinan 250014, China
| | - Dali Yu
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- Department of Life Science, Qilu Normal University, Jinan 250013, China
| | - Shichao Ren
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Shufeng Sun
- Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Linde Liu
- College of Life Science, Ludong University, Yantai 264025, China
| | - Tijs Ketelaar
- Laboratory of Cell Biology, Wageningen University, 6708PB Wageningen, The Netherlands
| | - Anne-Mie C. Emons
- Laboratory of Cell Biology, Wageningen University, 6708PB Wageningen, The Netherlands
| | - Chun-Ming Liu
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- Address correspondence to
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95
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Vaškovičová K, Žárský V, Rösel D, Nikolič M, Buccione R, Cvrčková F, Brábek J. Invasive cells in animals and plants: searching for LECA machineries in later eukaryotic life. Biol Direct 2013; 8:8. [PMID: 23557484 PMCID: PMC3663805 DOI: 10.1186/1745-6150-8-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2012] [Accepted: 03/21/2013] [Indexed: 02/08/2023] Open
Abstract
Invasive cell growth and migration is usually considered a specifically metazoan phenomenon. However, common features and mechanisms of cytoskeletal rearrangements, membrane trafficking and signalling processes contribute to cellular invasiveness in organisms as diverse as metazoans and plants – two eukaryotic realms genealogically connected only through the last common eukaryotic ancestor (LECA). By comparing current understanding of cell invasiveness in model cell types of both metazoan and plant origin (invadopodia of transformed metazoan cells, neurites, pollen tubes and root hairs), we document that invasive cell behavior in both lineages depends on similar mechanisms. While some superficially analogous processes may have arisen independently by convergent evolution (e.g. secretion of substrate- or tissue-macerating enzymes by both animal and plant cells), at the heart of cell invasion is an evolutionarily conserved machinery of cellular polarization and oriented cell mobilization, involving the actin cytoskeleton and the secretory pathway. Its central components - small GTPases (in particular RHO, but also ARF and Rab), their specialized effectors, actin and associated proteins, the exocyst complex essential for polarized secretion, or components of the phospholipid- and redox- based signalling circuits (inositol-phospholipid kinases/PIP2, NADPH oxidases) are aparently homologous among plants and metazoans, indicating that they were present already in LECA. Reviewer: This article was reviewed by Arcady Mushegian, Valerian Dolja and Purificacion Lopez-Garcia.
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Affiliation(s)
- Katarína Vaškovičová
- Department of Cell Biology, Faculty of Science, Charles University in Prague, Vinicna 7, 128 43, Prague 2, Czech Republic
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96
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Krause C, Richter S, Knöll C, Jürgens G. Plant secretome - from cellular process to biological activity. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2013; 1834:2429-41. [PMID: 23557863 DOI: 10.1016/j.bbapap.2013.03.024] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Revised: 03/19/2013] [Accepted: 03/25/2013] [Indexed: 10/27/2022]
Abstract
Recent studies suggest that plants secrete a large number of proteins and peptides into the extracellular space. Secreted proteins play a crucial role in stress response, communication and development of organisms. Here we review the current knowledge of the secretome of more than ten plant species, studied in natural conditions or during (a)biotic stress. This review not only deals with the classical secretory route via endoplasmic reticulum and Golgi followed by proteins containing a known N-terminal signal peptide, but also covers new findings about unconventional secretion of leaderless proteins. We describe alternative secretion pathways and the involved compartments like the recently discovered EXPO. The well characterized secreted peptides that function as ligands of receptor proteins exemplify the biological significance and activity of the secretome. This article is part of a Special Issue entitled: An Updated Secretome.
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Affiliation(s)
- Cornelia Krause
- Center for Plant Molecular Biology (ZMBP), University of Tübingen, Auf der Morgenstelle 3, 72076 Tübingen, Germany
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97
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Ostertag M, Stammler J, Douchkov D, Eichmann R, Hückelhoven R. The conserved oligomeric Golgi complex is involved in penetration resistance of barley to the barley powdery mildew fungus. MOLECULAR PLANT PATHOLOGY 2013; 14:230-40. [PMID: 23145810 PMCID: PMC6638642 DOI: 10.1111/j.1364-3703.2012.00846.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Membrane trafficking is vital to plant development and adaptation to the environment. It is suggested that post-Golgi vesicles and multivesicular bodies are essential for plant defence against directly penetrating fungal parasites at the cell wall. However, the actual plant proteins involved in membrane transport for defence are largely unidentified. We applied a candidate gene approach and single cell transient-induced gene silencing for the identification of membrane trafficking proteins of barley involved in the response to the fungal pathogen Blumeria graminis f.sp. hordei. This revealed potential components of vesicle tethering complexes [putative exocyst subunit HvEXO70F-like and subunits of the conserved oligomeric Golgi (COG) complex] and Golgi membrane trafficking (COPIγ coatomer and HvYPT1-like RAB GTPase) as essential for resistance to fungal penetration into the host cell.
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Affiliation(s)
- Maya Ostertag
- Lehrstuhl für Phytopathologie, Technische Universität München, Freising-Weihenstephan, Germany
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98
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van Gisbergen PAC, Bezanilla M. Plant formins: membrane anchors for actin polymerization. Trends Cell Biol 2013; 23:227-33. [PMID: 23317636 DOI: 10.1016/j.tcb.2012.12.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Revised: 12/06/2012] [Accepted: 12/10/2012] [Indexed: 11/18/2022]
Abstract
In plants, the actin cytoskeleton plays a fundamental role in intracellular transport, cell growth, and morphology. Formins are central regulators of actin polymerization and actin-based processes in many eukaryotes. Plants have a diverse family of formins and this diversity arose early in land plant evolution, probably deriving from family expansion and domain acquisition. Recently, formins from different plant lineages have been studied and the focus of these studies is beginning to shift from biochemical characterization to in vivo function. In vivo studies have shown that distinct biochemical activities confer specific cellular functions. Despite these differences, many plant formins have in common a direct link to the plasma membrane, suggesting that formins in plants are important links between the plasma membrane and actin remodeling.
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99
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Stegmann M, Anderson RG, Westphal L, Rosahl S, McDowell JM, Trujillo M. The exocyst subunit Exo70B1 is involved in the immune response of Arabidopsis thaliana to different pathogens and cell death. PLANT SIGNALING & BEHAVIOR 2013; 8:e27421. [PMID: 24389869 PMCID: PMC4091220 DOI: 10.4161/psb.27421] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Revised: 12/03/2013] [Accepted: 12/03/2013] [Indexed: 05/20/2023]
Abstract
Components of the vesicle trafficking machinery are central to the immune response in plants. The role of vesicle trafficking during pre-invasive penetration resistance has been well documented. However, emerging evidence also implicates vesicle trafficking in early immune signaling. Here we report that Exo70B1, a subunit of the exocyst complex which mediates early tethering during exocytosis is involved in resistance. We show that exo70B1 mutants display pathogen-specific immuno-compromised phenotypes. We also show that exo70B1 mutants display lesion-mimic cell death, which in combination with the reduced responsiveness to pathogen-associated molecular patterns (PAMPs) results in complex immunity-related phenotypes.
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Affiliation(s)
- Martin Stegmann
- Leibniz Institute of Plant Biochemistry; Halle, (Saale) Germany
| | - Ryan G Anderson
- Department of Plant Pathology, Physiology, & Weed Science; Virginia Tech; Blacksburg, VA USA
| | - Lore Westphal
- Leibniz Institute of Plant Biochemistry; Halle, (Saale) Germany
| | - Sabine Rosahl
- Leibniz Institute of Plant Biochemistry; Halle, (Saale) Germany
| | - John M McDowell
- Department of Plant Pathology, Physiology, & Weed Science; Virginia Tech; Blacksburg, VA USA
| | - Marco Trujillo
- Leibniz Institute of Plant Biochemistry; Halle, (Saale) Germany
- Correspondence to: Marco Trujillo,
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100
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Abstract
Tip growth is employed throughout the plant kingdom. Our understanding of tip growth has benefited from modern tools in molecular genetics, which have enabled the functional characterization of proteins mediating tip growth. Here we first discuss the evolutionary role of tip growth in land plants and then describe the prominent model tip-growth systems, elaborating on some advantages and disadvantages of each. Next we review the organization of tip-growing cells, the role of the cytoskeleton, and recent developments concerning the physiological basis of tip growth. Finally, we review advances in the understanding of the extracellular signals that are known to guide tip-growing cells.
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Affiliation(s)
- Caleb M Rounds
- Department of Biological Sciences, Mount Holyoke College, South Hadley, MA 01075, USA
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