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Ohba Y, Yoshihara S, Sato R, Matsuoka K, Asahina M, Satoh S, Iwai H. Plasmodesmata callose binding protein 2 contributes to the regulation of cambium/phloem formation and auxin response during the tissue reunion process in incised Arabidopsis stem. JOURNAL OF PLANT RESEARCH 2023; 136:865-877. [PMID: 37707645 DOI: 10.1007/s10265-023-01494-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 08/31/2023] [Indexed: 09/15/2023]
Abstract
Plants are exposed to a variety of biotic and abiotic stresses, including wounding at the stem. The healing process (tissue reunion) begins immediately after stem wounding. The plant hormone auxin plays an important role during tissue reunion. In decapitated stems, auxin transport from the shoot apex is reduced and tissue reunion does not occur but is restored by application of indole-3-acetic acid (IAA). In this study, we found that plasmodesmata callose binding protein 2 (PDCB2) affects the expansion of the cambium/phloem region via changes in auxin response during the process of tissue reunion. PDCB2 was expressed in the cortex and endodermis on the incised side of stems 1-3 days after incision. PDCB2-knockout plants showed reduced callose deposition at plasmodesmata and DR5::GUS activity in the endodermis/cortex in the upper region of the incision accompanied by an increase in size of the cambium/phloem region during tissue reunion. In addition, PIN(PIN-FORMED)3, which is involved in lateral auxin transport, was induced by auxin in the cambium/phloem and endodermis/cortex in the upper part of the incision in wild type, but its expression of PIN3 was decreased in pdcb2 mutant. Our results suggest that PDCB2 contributes to the regulation of cambium/phloem development via auxin response.
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Affiliation(s)
- Yusuke Ohba
- Graduate School of Life and Environmental Science, University of Tsukuba, Tsukuba, Ibaraki, 305-8572, Japan
| | - Sakura Yoshihara
- Graduate School of Life and Environmental Science, University of Tsukuba, Tsukuba, Ibaraki, 305-8572, Japan
| | - Ryosuke Sato
- Department of Biosciences, Teikyo University, Utsunomiya, Tochigi, 320-8551, Japan
| | - Keita Matsuoka
- Department of Biosciences, Teikyo University, Utsunomiya, Tochigi, 320-8551, Japan
| | - Masashi Asahina
- Department of Biosciences, Teikyo University, Utsunomiya, Tochigi, 320-8551, Japan
- Advanced Instrumental Analysis Center, Teikyo University, Utsunomiya, Tochigi, 320-8551, Japan
| | - Shinobu Satoh
- Institute of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8572, Japan
| | - Hiroaki Iwai
- Institute of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8572, Japan.
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2
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Sun H, Jing X, Wang C, Wang P, Huang Z, Sun B, Li P, Li H, Zhang C. The Great Game between Plants and Viruses: A Focus on Protein Homeostasis. Int J Mol Sci 2023; 24:12582. [PMID: 37628763 PMCID: PMC10454472 DOI: 10.3390/ijms241612582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 07/31/2023] [Accepted: 08/03/2023] [Indexed: 08/27/2023] Open
Abstract
Plant viruses are tiny pathogenic obligate parasites that cause significant damage to global crop production. They exploit and manipulate the cellular components of host plants to ensure their own survival. In response, plants activate multiple defense signaling pathways, such as gene silencing and plant hormone signaling, to hinder virus propagation. Growing evidence suggests that the regulation of protein homeostasis plays a vital role in the ongoing battle between plants and viruses. The ubiquitin-proteasome-degradation system (UPS) and autophagy, as two major protein-degradation pathways, are widely utilized by plants and viruses in their arms race. One the one hand, these pathways act as essential components of plant's antiviral defense system by facilitating the degradation of viral proteins; on the other hand, viruses exploit the UPS and autophagy to create a favorable intracellular environment for viral infection. This review aims to provide a comprehensive summary of the events involved in protein homeostasis regulation during viral infection in plants. Gaining knowledge in this area will enhance our understanding of the complex interplay between plants and viruses.
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Affiliation(s)
- Hangjun Sun
- The Engineering Research Center for Plant Health Protection Technology in Henan Province, Henan Agricultural University, Zhengzhou 450002, China
- Department of Plant Pathology, College of Plant Protection, Henan Agricultural University, Zhengzhou 450002, China
| | - Xinxin Jing
- The Engineering Research Center for Plant Health Protection Technology in Henan Province, Henan Agricultural University, Zhengzhou 450002, China
- Department of Plant Pathology, College of Plant Protection, Henan Agricultural University, Zhengzhou 450002, China
| | - Chaonan Wang
- The Engineering Research Center for Plant Health Protection Technology in Henan Province, Henan Agricultural University, Zhengzhou 450002, China
- Department of Plant Pathology, College of Plant Protection, Henan Agricultural University, Zhengzhou 450002, China
| | - Pengyue Wang
- The Engineering Research Center for Plant Health Protection Technology in Henan Province, Henan Agricultural University, Zhengzhou 450002, China
- Department of Plant Pathology, College of Plant Protection, Henan Agricultural University, Zhengzhou 450002, China
| | - Ziting Huang
- The Engineering Research Center for Plant Health Protection Technology in Henan Province, Henan Agricultural University, Zhengzhou 450002, China
- Department of Plant Pathology, College of Plant Protection, Henan Agricultural University, Zhengzhou 450002, China
| | - Bingjian Sun
- The Engineering Research Center for Plant Health Protection Technology in Henan Province, Henan Agricultural University, Zhengzhou 450002, China
- Department of Plant Pathology, College of Plant Protection, Henan Agricultural University, Zhengzhou 450002, China
| | - Pengbai Li
- The Engineering Research Center for Plant Health Protection Technology in Henan Province, Henan Agricultural University, Zhengzhou 450002, China
- Department of Plant Pathology, College of Plant Protection, Henan Agricultural University, Zhengzhou 450002, China
| | - Honglian Li
- The Engineering Research Center for Plant Health Protection Technology in Henan Province, Henan Agricultural University, Zhengzhou 450002, China
- Department of Plant Pathology, College of Plant Protection, Henan Agricultural University, Zhengzhou 450002, China
| | - Chao Zhang
- The Engineering Research Center for Plant Health Protection Technology in Henan Province, Henan Agricultural University, Zhengzhou 450002, China
- Department of Plant Pathology, College of Plant Protection, Henan Agricultural University, Zhengzhou 450002, China
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Real N, Villar I, Serrano I, Guiu-Aragonés C, Martín-Hernández AM. Mutations in CmVPS41 controlling resistance to cucumber mosaic virus display specific subcellular localization. PLANT PHYSIOLOGY 2023; 191:1596-1611. [PMID: 36527697 PMCID: PMC10022621 DOI: 10.1093/plphys/kiac583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 11/29/2022] [Indexed: 06/17/2023]
Abstract
Resistance to cucumber mosaic virus (CMV) in melon (Cucumis melo L.) has been described in several exotic accessions and is controlled by a recessive resistance gene, cmv1, that encodes a vacuolar protein sorting 41 (CmVPS41). cmv1 prevents systemic infection by restricting the virus to the bundle sheath cells, preventing viral phloem entry. CmVPS41 from different resistant accessions carries two causal mutations, either a G85E change, found in Pat-81 and Freeman's cucumber, or L348R, found in PI161375, cultivar Songwhan Charmi (SC). Here, we analyzed the subcellular localization of CmVPS41 in Nicotiana benthamiana and found differential structures in resistant and susceptible accessions. Susceptible accessions showed nuclear and membrane spots and many transvacuolar strands, whereas the resistant accessions showed many intravacuolar invaginations. These specific structures colocalized with late endosomes. Artificial CmVPS41 carrying individual mutations causing resistance in the genetic background of CmVPS41 from the susceptible variety Piel de Sapo (PS) revealed that the structure most correlated with resistance was the absence of transvacuolar strands. Coexpression of CmVPS41 with viral movement proteins, the determinant of virulence, did not change these localizations; however, infiltration of CmVPS41 from either SC or PS accessions in CMV-infected N. benthamiana leaves showed a localization pattern closer to each other, with up to 30% cells showing some membrane spots in the CmVPS41SC and fewer transvacuolar strands (reduced from a mean of 4 to 1-2) with CmVPS41PS. Our results suggest that the distribution of CmVPS41PS in late endosomes includes transvacuolar strands that facilitate CMV infection and that CmVPS41 re-localizes during viral infection.
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Affiliation(s)
- Núria Real
- Centre for Research in Agricultural Genomics (CRAG) CSIC-IRTA-UAB-UB, C/Vall Moronta, Edifici CRAG, Bellaterra (Cerdanyola del Vallés), 08193 Barcelona, Spain
| | - Irene Villar
- Centre for Research in Agricultural Genomics (CRAG) CSIC-IRTA-UAB-UB, C/Vall Moronta, Edifici CRAG, Bellaterra (Cerdanyola del Vallés), 08193 Barcelona, Spain
- Universidad de Zaragoza, Calle Pedro Cerbuna, 12, 50009 Zaragoza, Spain
| | - Irene Serrano
- Laboratoire des Interactions des Plantes et Microorganismes, CNRS, 31326 Toulouse, France
| | - Cèlia Guiu-Aragonés
- Centre for Research in Agricultural Genomics (CRAG) CSIC-IRTA-UAB-UB, C/Vall Moronta, Edifici CRAG, Bellaterra (Cerdanyola del Vallés), 08193 Barcelona, Spain
| | - Ana Montserrat Martín-Hernández
- Centre for Research in Agricultural Genomics (CRAG) CSIC-IRTA-UAB-UB, C/Vall Moronta, Edifici CRAG, Bellaterra (Cerdanyola del Vallés), 08193 Barcelona, Spain
- Institut de Recerca i Tecnologia Agroalimentàries (IRTA), Edifici CRAG, C/ Vall Moronta, Bellaterra (Cerdanyola del Vallés), 08193 Barcelona, Spain
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4
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He R, Li Y, Bernards MA, Wang A. Manipulation of the Cellular Membrane-Cytoskeleton Network for RNA Virus Replication and Movement in Plants. Viruses 2023; 15:744. [PMID: 36992453 PMCID: PMC10056259 DOI: 10.3390/v15030744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 03/10/2023] [Accepted: 03/11/2023] [Indexed: 03/15/2023] Open
Abstract
Viruses infect all cellular life forms and cause various diseases and significant economic losses worldwide. The majority of viruses are positive-sense RNA viruses. A common feature of infection by diverse RNA viruses is to induce the formation of altered membrane structures in infected host cells. Indeed, upon entry into host cells, plant-infecting RNA viruses target preferred organelles of the cellular endomembrane system and remodel organellar membranes to form organelle-like structures for virus genome replication, termed as the viral replication organelle (VRO) or the viral replication complex (VRC). Different viruses may recruit different host factors for membrane modifications. These membrane-enclosed virus-induced replication factories provide an optimum, protective microenvironment to concentrate viral and host components for robust viral replication. Although different viruses prefer specific organelles to build VROs, at least some of them have the ability to exploit alternative organellar membranes for replication. Besides being responsible for viral replication, VROs of some viruses can be mobile to reach plasmodesmata (PD) via the endomembrane system, as well as the cytoskeleton machinery. Viral movement protein (MP) and/or MP-associated viral movement complexes also exploit the endomembrane-cytoskeleton network for trafficking to PD where progeny viruses pass through the cell-wall barrier to enter neighboring cells.
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Affiliation(s)
- Rongrong He
- London Research and Development Centre, Agriculture and Agri-Food Canada, 1391 Sandford St., London, ON N5V 4T3, Canada
- Department of Biology, University of Western Ontario, 1151 Richmond St. N., London, ON N6A 5B7, Canada
| | - Yinzi Li
- London Research and Development Centre, Agriculture and Agri-Food Canada, 1391 Sandford St., London, ON N5V 4T3, Canada
| | - Mark A. Bernards
- Department of Biology, University of Western Ontario, 1151 Richmond St. N., London, ON N6A 5B7, Canada
| | - Aiming Wang
- London Research and Development Centre, Agriculture and Agri-Food Canada, 1391 Sandford St., London, ON N5V 4T3, Canada
- Department of Biology, University of Western Ontario, 1151 Richmond St. N., London, ON N6A 5B7, Canada
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5
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The Ubiquitin–Proteasome System (UPS) and Viral Infection in Plants. PLANTS 2022; 11:plants11192476. [PMID: 36235343 PMCID: PMC9572368 DOI: 10.3390/plants11192476] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 09/12/2022] [Accepted: 09/19/2022] [Indexed: 11/17/2022]
Abstract
The ubiquitin–proteasome system (UPS) is crucial in maintaining cellular physiological balance. The UPS performs quality control and degrades proteins that have already fulfilled their regulatory purpose. The UPS is essential for cellular and organic homeostasis, and its functions regulate DNA repair, gene transcription, protein activation, and receptor trafficking. Besides that, the UPS protects cellular immunity and acts on the host’s defense system. In order to produce successful infections, viruses frequently need to manipulate the UPS to maintain the proper level of viral proteins and hijack defense mechanisms. This review highlights and updates the mechanisms and strategies used by plant viruses to subvert the defenses of their hosts. Proteins involved in these mechanisms are important clues for biotechnological approaches in viral resistance.
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Zhang Z, Xie Y, Sun P, Zhang F, Zheng P, Wang X, You C, Hao Y. Nitrate-inducible MdBT2 acts as a restriction factor to limit apple necrotic mosaic virus genome replication in Malus domestica. MOLECULAR PLANT PATHOLOGY 2022; 23:383-399. [PMID: 34837323 PMCID: PMC8828459 DOI: 10.1111/mpp.13166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Apple necrotic mosaic virus (ApNMV) is highly associated with the occurrence of apple mosaic disease in China. However, ApNMV-host interactions and defence mechanisms of host plants against this virus are poorly studied. Here, we report that nitrate treatment restrains ApNMV genomic RNA accumulation by destabilizing viral replication protein 1a through the MdBT2-mediated ubiquitin-proteasome pathway. MdBT2, a nitrate-responsive BTB/TAZ domain-containing protein, was identified in a yeast two-hybrid screen of an apple cDNA library using viral protein 1a as bait, and 1a was further confirmed to interact with MdBT2 both in vivo and in vitro. It was further verified that MdBT2 promoted the ubiquitination and degradation of viral protein 1a through the ubiquitin-proteasome pathway in an MdCUL3A-independent manner. Viral genomic RNA accumulation was reduced in MdBT2-overexpressing transgenic apple leaves but enhanced in MdBT2-antisense leaves compared to the wild type. Moreover, MdBT2 was found to interfere with the interaction between viral replication proteins 1a and 2apol by competitively interacting with 1a. Taken together, our results demonstrate that nitrate-inducible MdBT2 functions as a limiting factor in ApNMV viral RNA accumulation by promoting the ubiquitination and degradation of viral protein 1a and interfering with interactions between viral replication proteins.
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Affiliation(s)
- Zhenlu Zhang
- State Key Laboratory of Crop BiologyCollege of Horticulture Science and EngineeringShandong Agricultural UniversityTai’anChina
| | - Yin‐Huan Xie
- State Key Laboratory of Crop BiologyCollege of Horticulture Science and EngineeringShandong Agricultural UniversityTai’anChina
| | - Ping Sun
- State Key Laboratory of Crop BiologyCollege of Horticulture Science and EngineeringShandong Agricultural UniversityTai’anChina
| | - Fu‐Jun Zhang
- State Key Laboratory of Crop BiologyCollege of Horticulture Science and EngineeringShandong Agricultural UniversityTai’anChina
| | - Peng‐Fei Zheng
- State Key Laboratory of Crop BiologyCollege of Horticulture Science and EngineeringShandong Agricultural UniversityTai’anChina
| | - Xiao‐Fei Wang
- State Key Laboratory of Crop BiologyCollege of Horticulture Science and EngineeringShandong Agricultural UniversityTai’anChina
| | - Chun‐Xiang You
- State Key Laboratory of Crop BiologyCollege of Horticulture Science and EngineeringShandong Agricultural UniversityTai’anChina
| | - Yu‐Jin Hao
- State Key Laboratory of Crop BiologyCollege of Horticulture Science and EngineeringShandong Agricultural UniversityTai’anChina
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7
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Dubiella U, Serrano I. The Ubiquitin Proteasome System as a Double Agent in Plant-Virus Interactions. PLANTS (BASEL, SWITZERLAND) 2021; 10:plants10050928. [PMID: 34066628 PMCID: PMC8148538 DOI: 10.3390/plants10050928] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 04/30/2021] [Accepted: 05/05/2021] [Indexed: 05/03/2023]
Abstract
The ubiquitin proteasome is a rapid, adaptive mechanism for selective protein degradation, crucial for proper plant growth and development. The ubiquitin proteasome system (UPS) has also been shown to be an integral part of plant responses to stresses, including plant defence against pathogens. Recently, significant progress has been made in the understanding of the involvement of the UPS in the signalling and regulation of the interaction between plants and viruses. This review aims to discuss the current knowledge about the response of plant viral infection by the UPS and how the viruses counteract this system, or even use it for their own benefit.
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Affiliation(s)
- Ullrich Dubiella
- KWS SAAT SE & Co. KGaA, Grimsehlstraße 31, 37574 Einbeck, Germany;
| | - Irene Serrano
- Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University Göttingen, 37077 Göttingen, Germany
- Correspondence:
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8
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Chen C, Vanneste S, Chen X. Review: Membrane tethers control plasmodesmal function and formation. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2021; 304:110800. [PMID: 33568299 DOI: 10.1016/j.plantsci.2020.110800] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 12/07/2020] [Accepted: 12/11/2020] [Indexed: 06/12/2023]
Abstract
Cell-to-cell communication is crucial in coordinating diverse biological processes in multicellular organisms. In plants, communication between adjacent cells occurs via nanotubular passages called plasmodesmata (PD). The PD passage is composed of an appressed endoplasmic reticulum (ER) internally, and plasma membrane (PM) externally, that traverses the cell wall, and associates with the actin-cytoskeleton. The coordination of the ER, PM and cytoskeleton plays a potential role in maintaining the architecture and conductivity of PD. Many data suggest that PD-associated proteins can serve as tethers that connect these structures in a functional PD, to regulate cell-to-cell communication. In this review, we summarize the organization and regulation of PD activity via tethering proteins, and discuss the importance of PD-mediated cell-to-cell communication in plant development and defense against environmental stress.
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Affiliation(s)
- Chaofan Chen
- College of Life Science and Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Fujian Agriculture and Forestry University, Fuzhou, China; FAFU-UCR Joint Center for Horticultural Biology and Metabolomics, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Steffen Vanneste
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium; Department of Plants and Crops, Ghent University, Coupure links 653, 9000 Ghent, Belgium; Lab of Plant Growth Analysis, Ghent University Global Campus, Songdomunhwa-Ro, 119, Yeonsu-gu, Incheon 21985, Republic of Korea
| | - Xu Chen
- FAFU-UCR Joint Center for Horticultural Biology and Metabolomics, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou, China.
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9
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Alers-Velazquez R, Jacques S, Muller C, Boldt J, Schoelz J, Leisner S. Cauliflower mosaic virus P6 inclusion body formation: A dynamic and intricate process. Virology 2021; 553:9-22. [PMID: 33197754 DOI: 10.1016/j.virol.2020.10.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 10/13/2020] [Accepted: 10/18/2020] [Indexed: 11/17/2022]
Abstract
During an infection, Cauliflower mosaic virus (CaMV) forms inclusion bodies (IBs) mainly composed of viral protein P6, where viral activities occur. Because viral processes occur in IBs, understanding the mechanisms by which they are formed is crucial. FL-P6 expressed in N. benthamiana leaves formed IBs of a variety of shapes and sizes. Small IBs were dynamic, undergoing fusion/dissociation events. Co-expression of actin-binding polypeptides with FL-P6 altered IB size distribution and inhibited movement. This suggests that IB movement is required for fusion and growth. A P6 deletion mutant was discovered that formed a single large IB per cell, which suggests it exhibited altered fusion/dissociation dynamics. Myosin-inhibiting drugs did not affect small IB movement, while those inhibiting actin polymerization did. Large IBs colocalized with components of the aggresome pathway, while small ones generally did not. This suggests a possible involvement of the aggresome pathway in large IB formation.
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Affiliation(s)
- Roberto Alers-Velazquez
- Department of Biological Sciences, University of Toledo, 2801 West Bancroft Street, Mail Stop 601, Toledo, OH, 43606, USA
| | - Sarah Jacques
- Department of Biological Sciences, University of Toledo, 2801 West Bancroft Street, Mail Stop 601, Toledo, OH, 43606, USA
| | - Clare Muller
- Department of Biological Sciences, University of Toledo, 2801 West Bancroft Street, Mail Stop 601, Toledo, OH, 43606, USA
| | - Jennifer Boldt
- USDA-Agricultural Research Service, Application Technology Research Unit, 2801 West Bancroft Street, Mail Stop 604, Toledo, OH, 43606, USA
| | - James Schoelz
- Division of Plant Sciences, University of Missouri, Columbia, MO, 65211, USA
| | - Scott Leisner
- Department of Biological Sciences, University of Toledo, 2801 West Bancroft Street, Mail Stop 601, Toledo, OH, 43606, USA.
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10
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Reagan BC, Burch-Smith TM. Viruses Reveal the Secrets of Plasmodesmal Cell Biology. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2020; 33:26-39. [PMID: 31715107 DOI: 10.1094/mpmi-07-19-0212-fi] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Plasmodesmata (PD) are essential for intercellular trafficking of molecules required for plant life, from small molecules like sugars and ions to macromolecules including proteins and RNA molecules that act as signals to regulate plant development and defense. As obligate intracellular pathogens, plant viruses have evolved to manipulate this communication system to facilitate the initial cell-to-cell and eventual systemic spread in their plant hosts. There has been considerable interest in how viruses manipulate the PD that connect the protoplasts of neighboring cells, and viruses have yielded invaluable tools for probing the structure and function of PD. With recent advances in biochemistry and imaging, we have gained new insights into the composition and structure of PD in the presence and absence of viruses. Here, we first discuss viral strategies for manipulating PD for their intercellular movement and examine how this has shed light on our understanding of native PD function. We then address the controversial role of the cytoskeleton in trafficking to and through PD. Finally, we address how viruses could alter PD structure and consider possible mechanisms of the phenomenon described as 'gating'. This discussion supports the significance of virus research in elucidating the properties of PD, these persistently enigmatic plant organelles.
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Affiliation(s)
- Brandon C Reagan
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, U.S.A
| | - Tessa M Burch-Smith
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, U.S.A
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11
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Xu Y, Da Silva WL, Qian Y, Gray SM. An aromatic amino acid and associated helix in the C-terminus of the potato leafroll virus minor capsid protein regulate systemic infection and symptom expression. PLoS Pathog 2018; 14:e1007451. [PMID: 30440046 PMCID: PMC6264904 DOI: 10.1371/journal.ppat.1007451] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Revised: 11/29/2018] [Accepted: 11/01/2018] [Indexed: 12/26/2022] Open
Abstract
The C-terminal region of the minor structural protein of potato leafroll virus (PLRV), known as the readthrough protein (RTP), is involved in efficient virus movement, tissue tropism and symptom development. Analysis of numerous C-terminal deletions identified a five-amino acid motif that is required for RTP function. A PLRV mutant expressing RTP with these five amino acids deleted (Δ5aa-RTP) was compromised in systemic infection and symptom expression. Although the Δ5aa-RTP mutant was able to move long distance, limited infection foci were observed in systemically infected leaves suggesting that these five amino acids regulate virus phloem loading in the inoculated leaves and/or unloading into the systemically infected tissues. The 5aa deletion did not alter the efficiency of RTP translation, nor impair RTP self-interaction or its interaction with P17, the virus movement protein. However, the deletion did alter the subcellular localization of RTP. When co-expressed with a PLRV infectious clone, a GFP tagged wild-type RTP was localized to discontinuous punctate spots along the cell periphery and was associated with plasmodesmata, although localization was dependent upon the developmental stage of the plant tissue. In contrast, the Δ5aa-RTP-GFP aggregated in the cytoplasm. Structural modeling indicated that the 5aa deletion would be expected to perturb an α-helix motif. Two of 30 plants infected with Δ5aa-RTP developed a wild-type virus infection phenotype ten weeks post-inoculation. Analysis of the virus population in these plants by deep sequencing identified a duplication of sequences adjacent to the deletion that were predicted to restore the α-helix motif. The subcellular distribution of the RTP is regulated by the 5-aa motif which is under strong selection pressure and in turn contributes to the efficient long distance movement of the virus and the induction of systemic symptoms.
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Affiliation(s)
- Yi Xu
- Section of Plant Pathology and Plant-Microbe Biology, School of Integrated Plant Science, Cornell University, Ithaca, NY, United States of America
| | - Washington Luis Da Silva
- Section of Plant Pathology and Plant-Microbe Biology, School of Integrated Plant Science, Cornell University, Ithaca, NY, United States of America
| | - Yajuan Qian
- Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Stewart M. Gray
- Section of Plant Pathology and Plant-Microbe Biology, School of Integrated Plant Science, Cornell University, Ithaca, NY, United States of America
- Emerging Pest and Pathogens Research Unit, USDA, ARS, Ithaca, NY, United States of America
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12
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DeBlasio SL, Xu Y, Johnson RS, Rebelo AR, MacCoss MJ, Gray SM, Heck M. The Interaction Dynamics of Two Potato Leafroll Virus Movement Proteins Affects Their Localization to the Outer Membranes of Mitochondria and Plastids. Viruses 2018; 10:E585. [PMID: 30373157 PMCID: PMC6265731 DOI: 10.3390/v10110585] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 10/19/2018] [Accepted: 10/19/2018] [Indexed: 12/15/2022] Open
Abstract
The Luteoviridae is an agriculturally important family of viruses whose replication and transport are restricted to plant phloem. Their genomes encode for four proteins that regulate viral movement. These include two structural proteins that make up the capsid and two non-structural proteins known as P3a and P17. Little is known about how these proteins interact with each other and the host to coordinate virus movement within and between cells. We used quantitative, affinity purification-mass spectrometry to show that the P3a protein of Potato leafroll virus complexes with virus and that this interaction is partially dependent on P17. Bimolecular complementation assays (BiFC) were used to validate that P3a and P17 self-interact as well as directly interact with each other. Co-localization with fluorescent-based organelle markers demonstrates that P3a directs P17 to the mitochondrial outer membrane while P17 regulates the localization of the P3a-P17 heterodimer to plastids. Residues in the C-terminus of P3a were shown to regulate P3a association with host mitochondria by using mutational analysis and also varying BiFC tag orientation. Collectively, our work reveals that the PLRV movement proteins play a game of intracellular hopscotch along host organelles to transport the virus to the cell periphery.
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Affiliation(s)
- Stacy L DeBlasio
- United States Department of Agriculture, Biological Integrated Pest Management Research Unit, Robert W. Holley Center for Agriculture and Health, 538 Tower Road, Ithaca, NY 14853, USA.
- Boyce Thompson Institute for Plant Research, Ithaca, NY 14853, USA.
| | - Yi Xu
- Section of Plant Pathology and Plant-Microbe Biology, School of Integrated Plant Science, Cornell University, Ithaca, NY 14853, USA.
| | - Richard S Johnson
- Department of Genome Sciences, University of Washington, Seattle WA 98109, USA.
| | - Ana Rita Rebelo
- Boyce Thompson Institute for Plant Research, Ithaca, NY 14853, USA.
| | - Michael J MacCoss
- Department of Genome Sciences, University of Washington, Seattle WA 98109, USA.
| | - Stewart M Gray
- United States Department of Agriculture, Biological Integrated Pest Management Research Unit, Robert W. Holley Center for Agriculture and Health, 538 Tower Road, Ithaca, NY 14853, USA.
- Section of Plant Pathology and Plant-Microbe Biology, School of Integrated Plant Science, Cornell University, Ithaca, NY 14853, USA.
| | - Michelle Heck
- United States Department of Agriculture, Biological Integrated Pest Management Research Unit, Robert W. Holley Center for Agriculture and Health, 538 Tower Road, Ithaca, NY 14853, USA.
- Boyce Thompson Institute for Plant Research, Ithaca, NY 14853, USA.
- Section of Plant Pathology and Plant-Microbe Biology, School of Integrated Plant Science, Cornell University, Ithaca, NY 14853, USA.
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13
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Bendix C, Lewis JD. The enemy within: phloem-limited pathogens. MOLECULAR PLANT PATHOLOGY 2018; 19:238-254. [PMID: 27997761 PMCID: PMC6638166 DOI: 10.1111/mpp.12526] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 12/06/2016] [Accepted: 12/08/2016] [Indexed: 05/06/2023]
Abstract
The growing impact of phloem-limited pathogens on high-value crops has led to a renewed interest in understanding how they cause disease. Although these pathogens cause substantial crop losses, many are poorly characterized. In this review, we present examples of phloem-limited pathogens that include intracellular bacteria with and without cell walls, and viruses. Phloem-limited pathogens have small genomes and lack many genes required for core metabolic processes, which is, in part, an adaptation to the unique phloem environment. For each pathogen class, we present multiple case studies to highlight aspects of disease caused by phloem-limited pathogens. The pathogens presented include Candidatus Liberibacter asiaticus (citrus greening), Arsenophonus bacteria, Serratia marcescens (cucurbit yellow vine disease), Candidatus Phytoplasma asteris (Aster Yellows Witches' Broom), Spiroplasma kunkelii, Potato leafroll virus and Citrus tristeza virus. We focus on commonalities in the virulence strategies of these pathogens, and aim to stimulate new discussions in the hope that widely applicable disease management strategies can be found.
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Affiliation(s)
- Claire Bendix
- United States Department of AgriculturePlant Gene Expression CenterAlbanyCA94710USA
| | - Jennifer D. Lewis
- United States Department of AgriculturePlant Gene Expression CenterAlbanyCA94710USA
- Department of Plant and Microbial BiologyUniversity of California, BerkeleyBerkeleyCA94720USA
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14
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Pitzalis N, Heinlein M. The roles of membranes and associated cytoskeleton in plant virus replication and cell-to-cell movement. JOURNAL OF EXPERIMENTAL BOTANY 2017; 69:117-132. [PMID: 29036578 DOI: 10.1093/jxb/erx334] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The infection of plants by viruses depends on cellular mechanisms that support the replication of the viral genomes, and the cell-to-cell and systemic movement of the virus via plasmodesmata (PD) and the connected phloem. While the propagation of some viruses requires the conventional endoplasmic reticulum (ER)-Golgi pathway, others replicate and spread between cells in association with the ER and are independent of this pathway. Using selected viruses as examples, this review re-examines the involvement of membranes and the cytoskeleton during virus infection and proposes potential roles of class VIII myosins and membrane-tethering proteins in controlling viral functions at specific ER subdomains, such as cortical microtubule-associated ER sites, ER-plasma membrane contact sites, and PD.
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15
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Boissinot S, Pichon E, Sorin C, Piccini C, Scheidecker D, Ziegler-Graff V, Brault V. Systemic Propagation of a Fluorescent Infectious Clone of a Polerovirus Following Inoculation by Agrobacteria and Aphids. Viruses 2017; 9:E166. [PMID: 28661469 PMCID: PMC5537658 DOI: 10.3390/v9070166] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 06/16/2017] [Accepted: 06/22/2017] [Indexed: 11/16/2022] Open
Abstract
A fluorescent viral clone of the polerovirus Turnip yellows virus (TuYV) was engineered by introducing the Enhanced Green Fluorescent Protein (EGFP) sequence into the non-structural domain sequence of the readthrough protein, a minor capsid protein. The resulting recombinant virus, referred to as TuYV-RTGFP, was infectious in several plant species when delivered by agroinoculation and invaded efficiently non-inoculated leaves. As expected for poleroviruses, which infect only phloem cells, the fluorescence emitted by TuYV-RTGFP was restricted to the vasculature of infected plants. In addition, TuYV-RTGFP was aphid transmissible and enabled the observation of the initial sites of infection in the phloem after aphid probing in epidermal cells. The aphid-transmitted virus moved efficiently to leaves distant from the inoculation sites and importantly retained the EGFP sequence in the viral genome. This work reports on the first engineered member in the Luteoviridae family that can be visualized by fluorescence emission in systemic leaves of different plant species after agroinoculation or aphid transmission.
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Affiliation(s)
- Sylvaine Boissinot
- Université de Strasbourg, Institut National de la Recherche Agronomique, SVQV UMR-A 1131, 68000 Colmar, France.
| | - Elodie Pichon
- Université de Strasbourg, Institut National de la Recherche Agronomique, SVQV UMR-A 1131, 68000 Colmar, France.
- UMR 385 BGPI, Institut National de la Recherche Agronomique-Centre de Coopération Internationale en Recherche Agronomique pour le Développement, SupAgro, CIRAD TA-A54/K, Campus International de Baillarguet, 34398 Montpellier, France.
| | - Céline Sorin
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, UPR 2357, Université de Strasbourg, 12 rue du Général Zimmer, 67084 Strasbourg, France.
- Institute of Plant Science Paris Saclay (IPS2), CNRS, INRA, University Paris Diderot, University of Paris-Saclay, 91405 Orsay, France.
| | - Céline Piccini
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, UPR 2357, Université de Strasbourg, 12 rue du Général Zimmer, 67084 Strasbourg, France.
| | - Danièle Scheidecker
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, UPR 2357, Université de Strasbourg, 12 rue du Général Zimmer, 67084 Strasbourg, France.
| | - Véronique Ziegler-Graff
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, UPR 2357, Université de Strasbourg, 12 rue du Général Zimmer, 67084 Strasbourg, France.
| | - Véronique Brault
- Université de Strasbourg, Institut National de la Recherche Agronomique, SVQV UMR-A 1131, 68000 Colmar, France.
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16
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Ju J, Kim K, Lee KJ, Lee WH, Ju HJ. Localization of Barley yellow dwarf virus Movement Protein Modulating Programmed Cell Death in Nicotiana benthamiana. THE PLANT PATHOLOGY JOURNAL 2017; 33:53-65. [PMID: 28167888 PMCID: PMC5291398 DOI: 10.5423/ppj.ft.10.2016.0233] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2016] [Accepted: 11/16/2016] [Indexed: 05/11/2023]
Abstract
Barley yellow dwarf virus (BYDV) belongs to Luteovirus and is limited only at phloem related tissues. An open reading frame (ORF) 4 of BYDV codes for the movement protein (MP) of BYDV gating plasmodesmata (PD) to facilitate virus movement. Like other Luteoviruses, ORF 4 of BYDV is embedded in the ORF3 but expressed from the different reading frame in leaky scanning manner. Although MP is a very important protein for systemic infection of BYDV, there was a little information. In this study, MP was characterized in terms of subcellular localization and programmed cell death (PCD). Gene of MP or its mutant (ΔMP) was expressed by Agroinfiltration method. MP was clearly localized at the nucleus and the PD, but ΔMP which was deleted distal N-terminus of MP showed no localization to PD exhibited the different target with original MP. In addition to PD localization, MP appeared associated with small granules in cytoplasm whereas ΔMP did not. MP associated with PD and small granules induced PCD, but ΔMP showed no association with PD and small granules did not exhibit PCD. Based on this study, the distal N-terminal region within MP is seemingly responsible for the localization of PD and the induction small granules and PCD induction. These results suggest that subcellular localization of BYDV MP may modulate the PCD in Nicotiana benthamiana.
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Affiliation(s)
- Jiwon Ju
- Department of Agricultural Biology, College of Agriculture & Life Sciences, Chonbuk National University, Jeonju 54896,
Korea
| | - Kangmin Kim
- Division of Biotechnology, Chonbuk National University, Iksan 54596,
Korea
- Plant Medicinal Research Center, College of Agriculture & Life Sciences, Chonbuk National University, Jeonju 54896,
Korea
| | - Kui-Jae Lee
- Division of Biotechnology, Chonbuk National University, Iksan 54596,
Korea
- Plant Medicinal Research Center, College of Agriculture & Life Sciences, Chonbuk National University, Jeonju 54896,
Korea
| | - Wang Hu Lee
- Department of Agricultural Biology, College of Agriculture & Life Sciences, Chonbuk National University, Jeonju 54896,
Korea
- Plant Medicinal Research Center, College of Agriculture & Life Sciences, Chonbuk National University, Jeonju 54896,
Korea
- Institute of Agricultural Science & Technology, College of Agriculture & Life Sciences, Chonbuk National University, Jeonju 54896,
Korea
| | - Ho-Jong Ju
- Department of Agricultural Biology, College of Agriculture & Life Sciences, Chonbuk National University, Jeonju 54896,
Korea
- Plant Medicinal Research Center, College of Agriculture & Life Sciences, Chonbuk National University, Jeonju 54896,
Korea
- Institute of Agricultural Science & Technology, College of Agriculture & Life Sciences, Chonbuk National University, Jeonju 54896,
Korea
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17
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Margaria P, Anderson CT, Turina M, Rosa C. Identification of Ourmiavirus 30K movement protein amino acid residues involved in symptomatology, viral movement, subcellular localization and tubule formation. MOLECULAR PLANT PATHOLOGY 2016; 17:1063-79. [PMID: 26637973 PMCID: PMC6638536 DOI: 10.1111/mpp.12348] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 11/26/2015] [Indexed: 05/03/2023]
Abstract
Several plant viruses encode movement proteins (MPs) classified in the 30K superfamily. Despite a great functional diversity, alignment analysis of MP sequences belonging to the 30K superfamily revealed the presence of a central core region, including amino acids potentially critical for MP structure and functionality. We performed alanine-scanning mutagenesis of the Ourmia melon virus (OuMV) MP, and studied the effects of amino acid substitutions on MP properties and virus infection. We identified five OuMV mutants that were impaired in systemic infection in Nicotiana benthamiana and Arabidopsis thaliana, and two mutants showing necrosis and pronounced mosaic symptoms, respectively, in N. benthamiana. Green fluorescent protein fusion constructs (GFP:MP) of movement-defective MP alleles failed to localize in distinct foci at the cell wall, whereas a GFP fusion with wild-type MP (GFP:MPwt) mainly co-localized with plasmodesmata and accumulated at the periphery of epidermal cells. The movement-defective mutants also failed to produce tubular protrusions in protoplasts isolated from infected leaves, suggesting a link between tubule formation and the ability of OuMV to move. In addition to providing data to support the importance of specific amino acids for OuMV MP functionality, we predict that these conserved residues might be critical for the correct folding and/or function of the MP of other viral species in the 30K superfamily.
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Affiliation(s)
- Paolo Margaria
- Department of Plant Pathology and Environmental Microbiology, Pennsylvania State University, University Park, PA, 16802, USA
| | - Charles T Anderson
- Department of Biology, Pennsylvania State University, University Park, PA, 16802, USA
| | - Massimo Turina
- Istituto per la Protezione Sostenibile delle Piante, CNR, 10135, Torino, Italy
| | - Cristina Rosa
- Department of Plant Pathology and Environmental Microbiology, Pennsylvania State University, University Park, PA, 16802, USA
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18
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Wang A, Zhou X. ER Stress, UPR and Virus Infections in Plants. CURRENT RESEARCH TOPICS IN PLANT VIROLOGY 2016. [PMCID: PMC7123154 DOI: 10.1007/978-3-319-32919-2_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/17/2023]
Abstract
The endoplasmic reticulum (ER) endomembrane is a central site for protein synthesis. Perturbation of ER homeostasis can result in an accumulation of unfolded proteins within the ER lumen, causing ER stress and the unfolded protein response (UPR). In humans, ER stress and UPR are closely associated with a vast number of diseases, including viral diseases. In plants, two arms that govern the UPR signaling network have been described: one that contains two ER membrane–associated transcription factors (bZIP17 and bZIP28) and the other that encompasses a dual protein kinase (RNA-splicing factor IRE1) and its target RNA (bZIP60). Although early studies mainly focus on the essential roles of the UPR in abiotic stresses, the significance of UPR in plant diseases caused by virus infections has recently drawn much attention. This chapter summarizes the latest scenario of ER stress and UPR in virus-infected plant cells, highlights the emerging roles of the IRE1 pathway in virus infections, and outlines exciting future directions to spark more research interest in the UPR field in plants.
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Affiliation(s)
- Aiming Wang
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, Ontario Canada
| | - Xueping Zhou
- State Key Laboratory for Biology of Plan, Chinese Academy of Agricultural Sciences, Beijing, China
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19
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Shen Q, Hu T, Bao M, Cao L, Zhang H, Song F, Xie Q, Zhou X. Tobacco RING E3 Ligase NtRFP1 Mediates Ubiquitination and Proteasomal Degradation of a Geminivirus-Encoded βC1. MOLECULAR PLANT 2016; 9:911-25. [PMID: 27018391 DOI: 10.1016/j.molp.2016.03.008] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Revised: 02/17/2016] [Accepted: 03/03/2016] [Indexed: 05/19/2023]
Abstract
The βC1 protein encoded by the Tomato yellow leaf curl China virus-associated betasatellite functions as a pathogenicity determinant. To better understand the molecular basis whereby βC1 functions in pathogenicity, a yeast two-hybrid screen of a tobacco cDNA library was carried out using βC1 as the bait. The screen revealed that βC1 interacts with a tobacco RING-finger protein designated NtRFP1, which was further confirmed by the bimolecular fluorescence complementation and co-immunoprecipitation assays in Nicotiana benthamiana cells. Expression of NtRFP1 was induced by βC1, and in vitro ubiquitination assays showed that NtRFP1 is a functional E3 ubiquitin ligase that mediates βC1 ubiquitination. In addition, βC1 was shown to be ubiquitinated in vivo and degraded by the plant 26S proteasome. After viral infection, plants overexpressing NtRFP1 developed attenuated symptoms, whereas plants with silenced expression of NtRFP1 showed severe symptoms. Other lines of evidence showed that NtRFP1 attenuates βC1-induced symptoms through promoting its degradation by the 26S proteasome. Taken together, our results suggest that tobacco RING E3 ligase NtRFP1 attenuates disease symptoms by interacting with βC1 to mediate its ubiquitination and degradation via the ubiquitin/26S proteasome system.
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Affiliation(s)
- Qingtang Shen
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Tao Hu
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Min Bao
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China; State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Linge Cao
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Huawei Zhang
- State Key Laboratory of Plant Genomics, National Center for Plant Gene Research, Chinese Academy of Sciences, Beijing 100101, China
| | - Fengmin Song
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Qi Xie
- State Key Laboratory of Plant Genomics, National Center for Plant Gene Research, Chinese Academy of Sciences, Beijing 100101, China
| | - Xueping Zhou
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China; State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
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20
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Feng Z, Xue F, Xu M, Chen X, Zhao W, Garcia-Murria MJ, Mingarro I, Liu Y, Huang Y, Jiang L, Zhu M, Tao X. The ER-Membrane Transport System Is Critical for Intercellular Trafficking of the NSm Movement Protein and Tomato Spotted Wilt Tospovirus. PLoS Pathog 2016; 12:e1005443. [PMID: 26863622 PMCID: PMC4749231 DOI: 10.1371/journal.ppat.1005443] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 01/17/2016] [Indexed: 12/15/2022] Open
Abstract
Plant viruses move through plasmodesmata to infect new cells. The plant endoplasmic reticulum (ER) is interconnected among cells via the ER desmotubule in the plasmodesma across the cell wall, forming a continuous ER network throughout the entire plant. This ER continuity is unique to plants and has been postulated to serve as a platform for the intercellular trafficking of macromolecules. In the present study, the contribution of the plant ER membrane transport system to the intercellular trafficking of the NSm movement protein and Tomato spotted wilt tospovirus (TSWV) is investigated. We showed that TSWV NSm is physically associated with the ER membrane in Nicotiana benthamiana plants. An NSm-GFP fusion protein transiently expressed in single leaf cells was trafficked into neighboring cells. Mutations in NSm that impaired its association with the ER or caused its mis-localization to other subcellular sites inhibited cell-to-cell trafficking. Pharmacological disruption of the ER network severely inhibited NSm-GFP trafficking but not GFP diffusion. In the Arabidopsis thaliana mutant rhd3 with an impaired ER network, NSm-GFP trafficking was significantly reduced, whereas GFP diffusion was not affected. We also showed that the ER-to-Golgi secretion pathway and the cytoskeleton transport systems were not involved in the intercellular trafficking of TSWV NSm. Importantly, TSWV cell-to-cell spread was delayed in the ER-defective rhd3 mutant, and this reduced viral infection was not due to reduced replication. On the basis of robust biochemical, cellular and genetic analysis, we established that the ER membrane transport system serves as an important direct route for intercellular trafficking of NSm and TSWV.
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Affiliation(s)
- Zhike Feng
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, People's Republic of China
| | - Fan Xue
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, People's Republic of China
| | - Min Xu
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, People's Republic of China
| | - Xiaojiao Chen
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, People's Republic of China
| | - Wenyang Zhao
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, People's Republic of China
| | - Maria J. Garcia-Murria
- Departament de Bioquímica i Biologia Molecular, Universitat de València, Burjassot, Spain
| | - Ismael Mingarro
- Departament de Bioquímica i Biologia Molecular, Universitat de València, Burjassot, Spain
| | - Yong Liu
- Institute of Plant Protection, Hunan Academy of Agricultural Sciences, Changsha, People's Republic of China
| | - Ying Huang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, People's Republic of China
| | - Lei Jiang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, People's Republic of China
| | - Min Zhu
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, People's Republic of China
| | - Xiaorong Tao
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, People's Republic of China
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21
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Chaparro-Garcia A, Schwizer S, Sklenar J, Yoshida K, Petre B, Bos JIB, Schornack S, Jones AME, Bozkurt TO, Kamoun S. Phytophthora infestans RXLR-WY Effector AVR3a Associates with Dynamin-Related Protein 2 Required for Endocytosis of the Plant Pattern Recognition Receptor FLS2. PLoS One 2015; 10:e0137071. [PMID: 26348328 PMCID: PMC4562647 DOI: 10.1371/journal.pone.0137071] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Accepted: 08/12/2015] [Indexed: 11/18/2022] Open
Abstract
Pathogens utilize effectors to suppress basal plant defense known as PTI (Pathogen-associated molecular pattern-triggered immunity). However, our knowledge of PTI suppression by filamentous plant pathogens, i.e. fungi and oomycetes, remains fragmentary. Previous work revealed that the co-receptor BAK1/SERK3 contributes to basal immunity against the potato pathogen Phytophthora infestans. Moreover BAK1/SERK3 is required for the cell death induced by P. infestans elicitin INF1, a protein with characteristics of PAMPs. The P. infestans host-translocated RXLR-WY effector AVR3a is known to supress INF1-mediated cell death by binding the plant E3 ligase CMPG1. In contrast, AVR3aKI-Y147del, a deletion mutant of the C-terminal tyrosine of AVR3a, fails to bind CMPG1 and does not suppress INF1-mediated cell death. Here, we studied the extent to which AVR3a and its variants perturb additional BAK1/SERK3-dependent PTI responses in N. benthamiana using the elicitor/receptor pair flg22/FLS2 as a model. We found that all tested variants of AVR3a suppress defense responses triggered by flg22 and reduce internalization of activated FLS2. Moreover, we discovered that AVR3a associates with the Dynamin-Related Protein 2 (DRP2), a plant GTPase implicated in receptor-mediated endocytosis. Interestingly, silencing of DRP2 impaired ligand-induced FLS2 internalization but did not affect internalization of the growth receptor BRI1. Our results suggest that AVR3a associates with a key cellular trafficking and membrane-remodeling complex involved in immune receptor-mediated endocytosis. We conclude that AVR3a is a multifunctional effector that can suppress BAK1/SERK3-mediated immunity through at least two different pathways.
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Affiliation(s)
| | - Simon Schwizer
- The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Jan Sklenar
- The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Kentaro Yoshida
- The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Benjamin Petre
- The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Jorunn I. B. Bos
- The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | | | | | - Tolga O. Bozkurt
- The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Sophien Kamoun
- The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
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22
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Smirnova E, Firth AE, Miller WA, Scheidecker D, Brault V, Reinbold C, Rakotondrafara AM, Chung BYW, Ziegler-Graff V. Discovery of a Small Non-AUG-Initiated ORF in Poleroviruses and Luteoviruses That Is Required for Long-Distance Movement. PLoS Pathog 2015; 11:e1004868. [PMID: 25946037 PMCID: PMC4422679 DOI: 10.1371/journal.ppat.1004868] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 04/08/2015] [Indexed: 02/03/2023] Open
Abstract
Viruses in the family Luteoviridae have positive-sense RNA genomes of around 5.2 to 6.3 kb, and they are limited to the phloem in infected plants. The Luteovirus and Polerovirus genera include all but one virus in the Luteoviridae. They share a common gene block, which encodes the coat protein (ORF3), a movement protein (ORF4), and a carboxy-terminal extension to the coat protein (ORF5). These three proteins all have been reported to participate in the phloem-specific movement of the virus in plants. All three are translated from one subgenomic RNA, sgRNA1. Here, we report the discovery of a novel short ORF, termed ORF3a, encoded near the 5’ end of sgRNA1. Initially, this ORF was predicted by statistical analysis of sequence variation in large sets of aligned viral sequences. ORF3a is positioned upstream of ORF3 and its translation initiates at a non-AUG codon. Functional analysis of the ORF3a protein, P3a, was conducted with Turnip yellows virus (TuYV), a polerovirus, for which translation of ORF3a begins at an ACG codon. ORF3a was translated from a transcript corresponding to sgRNA1 in vitro, and immunodetection assays confirmed expression of P3a in infected protoplasts and in agroinoculated plants. Mutations that prevent expression of P3a, or which overexpress P3a, did not affect TuYV replication in protoplasts or inoculated Arabidopsis thaliana leaves, but prevented virus systemic infection (long-distance movement) in plants. Expression of P3a from a separate viral or plasmid vector complemented movement of a TuYV mutant lacking ORF3a. Subcellular localization studies with fluorescent protein fusions revealed that P3a is targeted to the Golgi apparatus and plasmodesmata, supporting an essential role for P3a in viral movement. In order to maximize coding capacity, RNA viruses often encode overlapping genes and use unusual translational control mechanisms. Plant viruses express proteins required for movement of the virus through the plant, often from non-canonically translated open reading frames (ORFs). Viruses in the economically important Luteoviridae family are confined to the phloem (vascular) tissue, probably due to their specialized phloem-specific movement proteins. These proteins are translated from one viral mRNA, sgRNA1, via initiation at more than one AUG codon to express overlapping genes, and by ribosomal read-through of a stop codon. Here, we describe yet another gene translated from sgRNA1, ORF3a. Translation of ORF3a initiates at a non-standard (not AUG) start codon. We found that ORF3a is not required for viral genome replication, but is required for long-distance movement of the virus in the plant. The movement function could be restored in trans by providing the ORF3a product, P3a, from another viral or plasmid vector. P3a localizes in the Golgi apparatus and adjacent to the plasmodesmata, supporting a role in intercellular movement. In summary, we used a powerful bioinformatic tool to discover a cryptic gene whose product is required for movement of a phloem-specific plant virus, revealing multiple levels of translational control that regulate expression of four proteins from a single mRNA.
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Affiliation(s)
- Ekaterina Smirnova
- Institut de Biologie Moléculaire des Plantes CNRS-UPR 2357, Université de Strasbourg, Strasbourg, France
| | - Andrew E. Firth
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
- * E-mail: (AEF); (WAM); (VZG)
| | - W. Allen Miller
- Institut de Biologie Moléculaire des Plantes CNRS-UPR 2357, Université de Strasbourg, Strasbourg, France
- Department of Plant Pathology and Microbiology, Iowa State University, Ames, Iowa, United States of America
- * E-mail: (AEF); (WAM); (VZG)
| | - Danièle Scheidecker
- Institut de Biologie Moléculaire des Plantes CNRS-UPR 2357, Université de Strasbourg, Strasbourg, France
| | | | | | - Aurélie M. Rakotondrafara
- Department of Plant Pathology, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Betty Y.-W. Chung
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
| | - Véronique Ziegler-Graff
- Institut de Biologie Moléculaire des Plantes CNRS-UPR 2357, Université de Strasbourg, Strasbourg, France
- * E-mail: (AEF); (WAM); (VZG)
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The Tomato yellow leaf curl virus V2 protein forms aggregates depending on the cytoskeleton integrity and binds viral genomic DNA. Sci Rep 2015; 5:9967. [PMID: 25940862 PMCID: PMC4419519 DOI: 10.1038/srep09967] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Accepted: 03/23/2015] [Indexed: 12/25/2022] Open
Abstract
The spread of Tomato yellow leaf curl virus (TYLCV) was accompanied by the formation of coat protein (CP) aggregates of increasing size in the cytoplasm and nucleus of infected tomato (Solanum lycopersicum) cells. In order to better understand the TYLCV-host interaction, we investigated the properties and the subcellular accumulation pattern of the non-structural viral protein V2. CP and V2 are the only sense-oriented genes on the virus circular single-stranded DNA genome. Similar to CP, V2 localized to cytoplasmic aggregates of increasing size and as infection progressed was also found in nuclei, where it co-localized with CP. V2 was associated with viral genomic DNA molecules, suggesting that V2 functions as a DNA shuttling protein. The formation and the 26S proteasome-mediated degradation of V2 aggregates were dependent on the integrity of the actin and microtubule cytoskeleton. We propose that the cytoskeleton-dependent formation and growth of V2 aggregates play an important role during TYLCV infection, and that microtubules and actin filaments are important for the delivery of V2 to the 26S proteasome.
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Plant virus replication and movement. Virology 2015; 479-480:657-71. [DOI: 10.1016/j.virol.2015.01.025] [Citation(s) in RCA: 136] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 01/19/2015] [Accepted: 01/28/2015] [Indexed: 01/10/2023]
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The plasmodesmal protein PDLP1 localises to haustoria-associated membranes during downy mildew infection and regulates callose deposition. PLoS Pathog 2014; 10:e1004496. [PMID: 25393742 PMCID: PMC4231120 DOI: 10.1371/journal.ppat.1004496] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 09/29/2014] [Indexed: 01/08/2023] Open
Abstract
The downy mildew pathogen Hyaloperonospora arabidopsidis (Hpa) is a filamentous oomycete that invades plant cells via sophisticated but poorly understood structures called haustoria. Haustoria are separated from the host cell cytoplasm and surrounded by an extrahaustorial membrane (EHM) of unknown origin. In some interactions, including Hpa-Arabidopsis, haustoria are progressively encased by host-derived, callose-rich materials but the molecular mechanisms by which callose accumulates around haustoria remain unclear. Here, we report that PLASMODESMATA-LOCATED PROTEIN 1 (PDLP1) is expressed at high levels in Hpa infected cells. Unlike other plasma membrane proteins, which are often excluded from the EHM, PDLP1 is located at the EHM in Hpa-infected cells prior to encasement. The transmembrane domain and cytoplasmic tail of PDLP1 are sufficient to convey this localization. PDLP1 also associates with the developing encasement but this association is lost when encasements are fully mature. We found that the pdlp1,2,3 triple mutant is more susceptible to Hpa while overexpression of PDLP1 enhances plant resistance, suggesting that PDLPs enhance basal immunity against Hpa. Haustorial encasements are depleted in callose in pdlp1,2,3 mutant plants whereas PDLP1 over-expression elevates callose deposition around haustoria and across the cell surface. These data indicate that PDLPs contribute to callose encasement of Hpa haustoria and suggests that the deposition of callose at haustoria may involve similar mechanisms to callose deposition at plasmodesmata.
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Gorovits R, Moshe A, Ghanim M, Czosnek H. Degradation mechanisms of the Tomato yellow leaf curl virus coat protein following inoculation of tomato plants by the whitefly Bemisia tabaci. PEST MANAGEMENT SCIENCE 2014; 70:1632-9. [PMID: 24464776 DOI: 10.1002/ps.3737] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Accepted: 01/16/2014] [Indexed: 05/10/2023]
Abstract
BACKGROUND Tomato yellow leaf curl virus (TYLCV) is a begomovirus infecting tomato cultures worldwide. TYLCV is transmitted to plants by the whitefly Bemisia tabaci. Once in the plant, the virus is subjected to attack by the host-plant defences, which may include sequestration in aggregates, proteolysis, ubiquitination, 26S proteasome degradation and autophagy. Elucidating how the virus avoids destruction will make it possible to understand infection and possibly devise countermeasures. RESULTS The accumulation of viral coat protein (CP) and of viral DNA in plants is a marker of a successful virus transmission by B. tabaci. In response to infection, tomato tissues display multiple ways of degrading TYLCV proteins and DNA. In this study it is shown that CP (in soluble and insoluble states) is the target of protease digestion, 26S proteasome degradation and autophagy. The highest degradation capacity was detected among soluble proteins and proteins in large aggregates/inclusion bodies; cytoplasmic extracts displayed higher activity than nuclear fractions. The very same fractions possessed the highest capacity to degrade viral genomic DNA. Separately, 26S proteasome degradation was associated with large aggregates (more pronounced in the nuclear than in the cytoplasmic fractions), which are indicators of a successful abduction of plants by viruses. Autophagy/lysosome/vacuole degradation was a characteristic of intermediate aggregates, sequestering the CP in the cytoplasm and retarding the development of large aggregates. Chloroplast proteases were active in soluble as well as in insoluble protein extracts. CONCLUSIONS To the best of the authors' knowledge, this study is the first attempt to identify elements of the virus-targeted degradation machinery, which is a part of the plant response to virus invasion.
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Affiliation(s)
- Rena Gorovits
- Institute of Plant Sciences and Genetics in Agriculture and the Otto Warburg Minerva Centre for Agricultural Biotechnology, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
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Sun L, Andika IB, Shen J, Yang D, Chen J. The P2 of Wheat yellow mosaic virus rearranges the endoplasmic reticulum and recruits other viral proteins into replication-associated inclusion bodies. MOLECULAR PLANT PATHOLOGY 2014; 15:466-78. [PMID: 24304930 PMCID: PMC6638913 DOI: 10.1111/mpp.12109] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Viruses commonly modify host endomembranes to facilitate biological processes in the viral life cycle. Infection by viruses belonging to the genus Bymovirus (family Potyviridae) has long been known to induce the formation of large membranous inclusion bodies in host cells, but their assembly and biological roles are still unclear. Immunoelectron microscopy of cells infected with the bymovirus Wheat yellow mosaic virus (WYMV) showed that P1, P2 and P3 are the major viral protein constituents of the membranous inclusions, whereas NIa-Pro (nuclear inclusion-a protease) and VPg (viral protein genome-linked) are probable minor components. P1, P2 and P3 associated with the endoplasmic reticulum (ER), but only P2 was able to rearrange ER and form large aggregate structures. Bioinformatic analyses and chemical experiments showed that P2 is an integral membrane protein and depends on the active secretory pathway to form aggregates of ER membranes. In planta and in vitro assays demonstrated that P2 interacts with P1, P3, NIa-Pro or VPg and recruits these proteins into the aggregates. In vivo RNA labelling using WYMV-infected wheat protoplasts showed that the synthesis of viral RNAs occurs in the P2-associated inclusions. Our results suggest that P2 plays a major role in the formation of membranous compartments that house the genomic replication of WYMV.
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Affiliation(s)
- Liying Sun
- State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, MoA Key Laboratory for Plant Protection and Biotechnology, Zhejiang Provincial Key Laboratory of Plant Virology, Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou, 310021, China
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28
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Factors that affect the intracellular localization and trafficking of African horse sickness virus core protein, VP7. Virology 2014; 456-457:279-91. [DOI: 10.1016/j.virol.2014.03.030] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 01/26/2014] [Accepted: 03/29/2014] [Indexed: 11/21/2022]
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Serra-Soriano M, Pallás V, Navarro JA. A model for transport of a viral membrane protein through the early secretory pathway: minimal sequence and endoplasmic reticulum lateral mobility requirements. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2014; 77:863-79. [PMID: 24438546 DOI: 10.1111/tpj.12435] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Revised: 12/30/2013] [Accepted: 01/09/2014] [Indexed: 05/19/2023]
Abstract
Viral movement proteins exploit host endomembranes and the cytoskeleton to move within the cell via routes that, in some cases, are dependent on the secretory pathway. For example, melon necrotic spot virus p7B, a type II transmembrane protein, leaves the endoplasmic reticulum (ER) through the COPII-dependent Golgi pathway to reach the plasmodesmata. Here we investigated the sequence requirements and putative mechanisms governing p7B transport through the early secretory pathway. Deletion of either the cytoplasmic N-terminal region (CR) or the luminal C-terminal region (LR) led to ER retention, suggesting that they are both essential for ER export. Through alanine-scanning mutagenesis, we identified residues in the CR and LR that are critical for both ER export and for viral cell-to-cell movement. Within the CR, alanine substitution of aspartic and proline residues in the DSSP β-turn motif (D7 AP10 A) led to movement of discrete structures along the cortical ER in an actin-dependent manner. In contrast, alanine substitution of a lysine residue in the LR (K49 A) resulted in a homogenous ER distribution of the movement protein and inhibition of ER-Golgi traffic. Moreover, the ability of p7B to recruit Sar1 to the ER membrane is lost in the D7 AP10 A mutant, but enhanced in the K49 A mutant. In addition, fluorescence recovery after photobleaching revealed that K49 A but not D7 AP10 A dramatically diminished protein lateral mobility. From these data, we propose a model whereby the LR directs actin-dependent mobility toward the cortical ER, where the cytoplasmic DSSP β-turn favors assembly of COPII vesicles for export of p7B from the ER.
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Affiliation(s)
- Marta Serra-Soriano
- Instituto de Biología Molecular y Celular de Plantas, Universitat Politècnica de València/Consejo Superior de Investigaciones Científicas, Avenida Ingeniero Fausto Elio s/n, 46022, Valencia, Spain
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30
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Baudisch B, Langner U, Garz I, Klösgen RB. The exception proves the rule? Dual targeting of nuclear-encoded proteins into endosymbiotic organelles. THE NEW PHYTOLOGIST 2014; 201:80-90. [PMID: 24024706 DOI: 10.1111/nph.12482] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2013] [Accepted: 08/05/2013] [Indexed: 05/17/2023]
Abstract
Plant cells harbor two types of endosymbiotic organelle: mitochondria and chloroplasts. As a consequence of endosymbiotic gene transfer, the majority of their proteins are encoded in the nucleus and post-translationally 're'-imported into the respective target organelle. The corresponding transport signals are usually selective for a single organelle, but several proteins are transported into both the mitochondria and chloroplasts. To estimate the number of proteins with such dual targeting properties in Arabidopsis, we classified the proteins encoded by nuclear genes of endosymbiotic origin according to the respective targeting specificity of their N-terminal transport signals as predicted by the TargetP software package. Selected examples of the resulting protein classes were subsequently analyzed by transient transformation assays as well as by in organello protein transport experiments. It was found that most proteins with high prediction values for both organelles show dual targeting with both experimental approaches. Unexpectedly, however, dual targeting was even found among those proteins that are predicted to be localized solely in one of the two endosymbiotic organelles. In total, among the 16 candidate proteins analyzed, we identified 10 proteins with dual targeting properties. This unexpectedly high proportion suggests that such transport properties are much more abundant than anticipated.
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Affiliation(s)
- Bianca Baudisch
- Institute of Biology - Plant Physiology, Martin Luther University Halle-Wittenberg, Weinbergweg 10, 06120, Halle (Saale), Germany
| | - Uwe Langner
- Institute of Biology - Plant Physiology, Martin Luther University Halle-Wittenberg, Weinbergweg 10, 06120, Halle (Saale), Germany
| | - Ingo Garz
- Institute of Biology - Plant Physiology, Martin Luther University Halle-Wittenberg, Weinbergweg 10, 06120, Halle (Saale), Germany
| | - Ralf Bernd Klösgen
- Institute of Biology - Plant Physiology, Martin Luther University Halle-Wittenberg, Weinbergweg 10, 06120, Halle (Saale), Germany
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31
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Feng Z, Chen X, Bao Y, Dong J, Zhang Z, Tao X. Nucleocapsid of Tomato spotted wilt tospovirus forms mobile particles that traffic on an actin/endoplasmic reticulum network driven by myosin XI-K. THE NEW PHYTOLOGIST 2013; 200:1212-24. [PMID: 24032608 DOI: 10.1111/nph.12447] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Accepted: 07/11/2013] [Indexed: 05/27/2023]
Abstract
A number of viral proteins from plant viruses, other than movement proteins, have been shown to traffic intracellularly along actin filaments and to be involved in viral infection. However, there has been no report that a viral capsid protein may traffic within a cell by utilizing the actin/endoplasmic reticulum (ER) network. We used Tomato spotted wilt tospovirus (TSWV) as a model virus to study the cell biological properties of a nucleocapsid (N) protein. We found that TSWV N protein was capable of forming highly motile cytoplasmic inclusions that moved along the ER and actin network. The disruption of actin filaments by latrunculin B, an actin-depolymerizing agent, almost stopped the intracellular movement of N inclusions, whereas treatment with a microtubule-depolymerizing reagent, oryzalin, did not. The over-expression of a myosin XI-K tail, functioning in a dominant-negative manner, completely halted the movement of N inclusions. Latrunculin B treatment strongly inhibited the formation of TSWV local lesions in Nicotiana tabacum cv Samsun NN and delayed systemic infection in N. benthamiana. Collectively, our findings provide the first evidence that the capsid protein of a plant virus has the novel property of intracellular trafficking. The findings add capsid protein as a new class of viral protein that traffics on the actin/ER system.
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Affiliation(s)
- Zhike Feng
- Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China
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32
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Agbeci M, Grangeon R, Nelson RS, Zheng H, Laliberté JF. Contribution of host intracellular transport machineries to intercellular movement of turnip mosaic virus. PLoS Pathog 2013; 9:e1003683. [PMID: 24098128 PMCID: PMC3789768 DOI: 10.1371/journal.ppat.1003683] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Accepted: 08/21/2013] [Indexed: 11/19/2022] Open
Abstract
The contribution of different host cell transport systems in the intercellular movement of turnip mosaic virus (TuMV) was investigated. To discriminate between primary infections and secondary infections associated with the virus intercellular movement, a gene cassette expressing GFP-HDEL was inserted adjacent to a TuMV infectious cassette expressing 6K₂:mCherry, both within the T-DNA borders of the binary vector pCambia. In this system, both gene cassettes were delivered to the same cell by a single binary vector and primary infection foci emitted green and red fluorescence while secondarily infected cells emitted only red fluorescence. Intercellular movement was measured at 72 hours post infiltration and was estimated to proceed at an average rate of one cell being infected every three hours over an observation period of 17 hours. To determine if the secretory pathway were important for TuMV intercellular movement, chemical and protein inhibitors that blocked both early and late secretory pathways were used. Treatment with Brefeldin A or Concanamycin A or expression of ARF1 or RAB-E1d dominant negative mutants, all of which inhibit pre- or post-Golgi transport, reduced intercellular movement by the virus. These treatments, however, did not inhibit virus replication in primary infected cells. Pharmacological interference assays using Tyrphostin A23 or Wortmannin showed that endocytosis was not important for TuMV intercellular movement. Lack of co-localization by endocytosed FM4-64 and Ara7 (AtRabF2b) with TuMV-induced 6K₂-tagged vesicles further supported this conclusion. Microfilament depolymerizing drugs and silencing expression of myosin XI-2 gene, but not myosin VIII genes, also inhibited TuMV intercellular movement. Expression of dominant negative myosin mutants confirmed the role played by myosin XI-2 as well as by myosin XI-K in TuMV intercellular movement. Using this dual gene cassette expression system and transport inhibitors, components of the secretory and actomyosin machinery were shown to be important for TuMV intercellular spread.
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Affiliation(s)
- Maxime Agbeci
- INRS-Institut Armand-Frappier, Laval, Québec, Canada
| | | | - Richard S. Nelson
- Plant Biology Division, Samuel Roberts Noble Foundation, Inc., Ardmore, Oklahoma, United States of America
| | - Huanquan Zheng
- Department of Biology, McGill University, Montréal, Québec, Canada
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Nakajima Y, Suzuki S. Environmental stresses induce misfolded protein aggregation in plant cells in a microtubule-dependent manner. Int J Mol Sci 2013; 14:7771-83. [PMID: 23574938 PMCID: PMC3645715 DOI: 10.3390/ijms14047771] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Revised: 03/25/2013] [Accepted: 03/27/2013] [Indexed: 12/02/2022] Open
Abstract
Misfolded protein aggregation in mammalian cells is one of the cellular responses to environmental stresses. However, the aggregation of misfolded proteins in plant cells exposed to environmental stresses is still poorly understood. Here, we report the misfolded protein aggregation in plant cells in response to environmental stresses, including ultraviolet (UV) radiation, heat stress and cold stress. Treatment of grape and tobacco cultured cells with MG-132, a proteasome inhibitor, induced misfolded protein aggregation. All of the environmental stresses examined induced the endoplasmic reticulum (ER) stress response in the cells. The cells under ER stress showed aggregation of misfolded proteins. The misfolded protein aggregation was completely inhibited by treatment of the cells with trichostatin A or colchicine, suggesting that the misfolded proteins might be aggregated in plant cells in a microtubule-dependent manner. Detected aggregates were initially observed immediately after exposure to the environmental stresses (1 min after UV radiation, 5 min after heat stress exposure, and 15 min after cold stress exposure). Based on these findings, we hypothesize that environmental stresses induce misfolded protein aggregation in plant cells in a microtubule-dependent manner.
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Affiliation(s)
- Yuko Nakajima
- Laboratory of Fruit Genetic Engineering, the Institute of Enology and Viticulture, University of Yamanashi, Kofu, Yamanashi 400-0005, Japan; E-Mail:
| | - Shunji Suzuki
- Laboratory of Fruit Genetic Engineering, the Institute of Enology and Viticulture, University of Yamanashi, Kofu, Yamanashi 400-0005, Japan; E-Mail:
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Lim HS, Lee MY, Moon JS, Moon JK, Yu YM, Cho IS, Bae H, deBoer M, Ju H, Hammond J, Jackson AO. Actin Cytoskeleton and Golgi Involvement in Barley stripe mosaic virus Movement and Cell Wall Localization of Triple Gene Block Proteins. THE PLANT PATHOLOGY JOURNAL 2013; 29:17-30. [PMID: 25288925 PMCID: PMC4174794 DOI: 10.5423/ppj.oa.09.2012.0144] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Revised: 10/08/2012] [Accepted: 10/10/2012] [Indexed: 05/29/2023]
Abstract
Barley stripe mosaic virus (BSMV) induces massive actin filament thickening at the infection front of infected Nicotiana benthamiana leaves. To determine the mechanisms leading to actin remodeling, fluorescent protein fusions of the BSMV triple gene block (TGB) proteins were coexpressed in cells with the actin marker DsRed: Talin. TGB ectopic expression experiments revealed that TGB3 is a major elicitor of filament thickening, that TGB2 resulted in formation of intermediate DsRed:Talin filaments, and that TGB1 alone had no obvious effects on actin filament structure. Latrunculin B (LatB) treatments retarded BSMV cell-to-cell movement, disrupted actin filament organization, and dramatically decreased the proportion of paired TGB3 foci appearing at the cell wall (CW). BSMV infection of transgenic plants tagged with GFP-KDEL exhibited membrane proliferation and vesicle formation that were especially evident around the nucleus. Similar membrane proliferation occurred in plants expressing TGB2 and/or TGB3, and DsRed: Talin fluorescence in these plants colocalized with the ER vesicles. TGB3 also associated with the Golgi apparatus and overlapped with cortical vesicles appearing at the cell periphery. Brefeldin A treatments disrupted Golgi and also altered vesicles at the CW, but failed to interfere with TGB CW localization. Our results indicate that actin cytoskeleton interactions are important in BSMV cell-to-cell movement and for CW localization of TGB3.
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Affiliation(s)
- Hyoun-Sub Lim
- Department of Applied Biology, Chungnam National University, Daejeon 305-764, Korea
| | - Mi Yeon Lee
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720 USA
| | - Jae Sun Moon
- Green Bio Research Center, Korea Research Institute of Bioscience & Biotechnology, Daejeon 305-333, Korea
| | - Jung-Kyung Moon
- National Institute of Crop Science, Suwon, Rural Development Administration, 441-707, Korea
| | - Yong-Man Yu
- Department of Applied Biology, Chungnam National University, Daejeon 305-764, Korea
| | - In Sook Cho
- National Institute of Horticultural & Herbal Science, Rural Development Administration, Suwon 441-440, Korea
| | - Hanhong Bae
- School of Biotechnology, Yeungnam University, Gyeongsan, Korea
| | - Matt deBoer
- Virology Department, Wageningen University, 6709 PD Wageningen, The Netherlands
| | - Hojong Ju
- Department of Agricultural Biology, Chonbuk National University, Jeonju 561-756, Korea
| | - John Hammond
- USDA-ARS, US National Arboretum, Floral and Nursery Plants Research Unit, Beltsville, MD 20705 USA
| | - Andrew O. Jackson
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720 USA
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Niehl A, Amari K, Heinlein M. CDC48 function during TMV infection: regulation of virus movement and replication by degradation? PLANT SIGNALING & BEHAVIOR 2013; 8:e22865. [PMID: 23154510 PMCID: PMC3656987 DOI: 10.4161/psb.22865] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2012] [Accepted: 11/12/2012] [Indexed: 05/21/2023]
Abstract
Cell-division-cycle protein 48 (CDC48) is an essential, conserved ATP-driven chaperone in eukaryotic cells, which functions in diverse cellular processes including the targeting of misfolded and aggregated proteins for degradation via proteasomal and aggresomal-autophagic pathways. We recently demonstrated that plant CDC48 localizes to and interacts with Tobacco mosaic virus (TMV) movement protein (MP) in ER-associated viral protein inclusions. Our data suggest that CDC48 participates in the clearance of these viral protein inclusions in an ER-assisted protein degradation (ERAD)-like mechanism. As TMV MP-inclusions formed at late infection stages resemble aggresomes, we here propose that TMV MP enters both, ERAD-like and aggresomal pathways in its host cells and that CDC48 coordinates these processes. Moreover, as viruses often exploit host pathways for replication and spread, we propose a model in which CDC48 functions in the degradation pathway of overaccumulating viral protein and also actively participates in the regulation of TMV replication and cell-to-cell movement.
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Affiliation(s)
- Annette Niehl
- Botany; Department of Environmental Sciences; University of Basel; Basel, Switzerland
- Correspondence to: Annette Niehl,
| | - Khalid Amari
- Botany; Department of Environmental Sciences; University of Basel; Basel, Switzerland
| | - Manfred Heinlein
- Botany; Department of Environmental Sciences; University of Basel; Basel, Switzerland
- Institut de Biologie Moléculaire des Plantes; UPR 2357 CNRS; Université de Strasbourg; Strasbourg, France
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Andika IB, Zheng S, Tan Z, Sun L, Kondo H, Zhou X, Chen J. Endoplasmic reticulum export and vesicle formation of the movement protein of Chinese wheat mosaic virus are regulated by two transmembrane domains and depend on the secretory pathway. Virology 2013; 435:493-503. [PMID: 23137810 DOI: 10.1016/j.virol.2012.10.024] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Revised: 09/10/2012] [Accepted: 10/15/2012] [Indexed: 12/15/2022]
Abstract
The 37K protein of Chinese wheat mosaic virus (CWMV) belongs to the 30K superfamily of plant virus movement proteins. CWMV 37K trans-complemented the cell-to-cell spread of a movement-defective Potato virus X. CWMV 37K fused to enhanced green fluorescent protein localized to plasmodesmata and formed endoplasmic reticulum (ER)-derived vesicular and large aggregate structures. CWMV 37K has two putative N-terminal transmembrane domains (TMDs). Mutations disrupting TMD1 or TMD2 impaired 37K movement function; those mutants were unable to form ER-derived structures but instead accumulated in the ER. Treatment with Brefeldin A or overexpression of the dominant negative mutant of Sar1 retained 37K in the ER, indicating that ER export of 37K is dependent on the secretory pathway. Moreover, CWMV 37K interacted with pectin methylesterases and mutations in TMD1 or TMD2 impaired this interaction in planta. The results suggest that the two TMDs regulate the movement function and intracellular transport of 37K.
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Affiliation(s)
- Ida Bagus Andika
- State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, Ministry of Agriculture Key Laboratory of Biotechnology in Plant Protection, Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, PR China
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Thran M, Link K, Sonnewald U. The Arabidopsis DCP2 gene is required for proper mRNA turnover and prevents transgene silencing in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2012; 72:368-77. [PMID: 22639932 DOI: 10.1111/j.1365-313x.2012.05066.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Post-transcriptional gene silencing often limits the over-expression of transgenes in transgenic plants. It involves RNA-DEPENDENT RNA POLYMERASE 6 (RDR6), which recognizes aberrant transcripts, such as inaccurately processed or uncapped mRNA, and triggers silencing of target transcripts. Here, we describe the isolation and characterization of an Arabidopsis mutant displaying increased transgene silencing (its1). Reduced accumulation of transgene mRNA in the its1 mutant background was accompanied by accumulation of transgene-specific siRNAs and was overcome by potyvirus infection. We therefore speculated that ITS1 is a suppressor of post-transcriptional gene silencing. Map-based cloning and subsequent complementation revealed that ITS1 encodes DECAPPING 2 (DCP2), which is crucial for decapping, a prerequisite for mRNA degradation. In agreement with the proposed function of DCP2, we found a reduced accumulation of uncapped mRNA in the its1 mutant. Furthermore, silencing in the its1 mutant was dependent on RDR6 function, suggesting that reduced decapping leads to accumulation of aberrant capped mRNA. Hence, we provide evidence for a class of aberrant mRNA that accumulates upon impaired mRNA decapping and triggers post-transcriptional gene silencing in Arabidopsis. As DCP2 knockouts cause post-embryo lethality, we isolated a hypomorphic dcp2 allele, providing insights into mRNA degradation and its interplay with post-transcriptional gene silencing.
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Affiliation(s)
- Moritz Thran
- Department of Biology, Friedrich Alexander University Erlangen-Nuremberg, Staudtstrasse 5, 91058 Erlangen, Germany
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Gorovits R, Moshe A, Kolot M, Sobol I, Czosnek H. Progressive aggregation of Tomato yellow leaf curl virus coat protein in systemically infected tomato plants, susceptible and resistant to the virus. Virus Res 2012; 171:33-43. [PMID: 23099086 DOI: 10.1016/j.virusres.2012.09.017] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Revised: 09/23/2012] [Accepted: 09/27/2012] [Indexed: 02/04/2023]
Abstract
Tomato yellow leaf curl virus (TYLCV) coat protein (CP) accumulated in tomato leaves during infection. The CP was immuno-detected in the phloem associated cells. At the early stages of infection, punctate signals were detected in the cytoplasm, while in the later stages aggregates of increasing size were localized in cytoplasm and nuclei. Sedimentation of protein extracts through sucrose gradients confirmed that progress of infection was accompanied by the formation of CP aggregates of increasing size. Genomic ssDNA was found in the cytoplasm and in the nucleus, while the dsDNA replicative form was exclusively associated with the nucleus. CP-DNA complexes were detected by immuno-capture PCR in nuclear and cytoplasmic large aggregates. Nuclear aggregates contained infectious particles transmissible to test plants by whiteflies. In contrast to susceptible tomatoes, the formation of large CP aggregates in resistant plants was delayed. By experimentally changing the level of resistance/susceptibility of plants, we showed that maintenance of midsized CP aggregates was associated with resistance, while large aggregates where characteristic of susceptibility. We propose that sequestering of virus CP into midsized aggregates and retarding the formation of large insoluble aggregates containing infectious particles is part of the response of resistant plants to TYLCV.
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Affiliation(s)
- Rena Gorovits
- Institute of Plant Sciences and Genetics in Agriculture and the Otto Warburg Minerva Center for Agricultural Biotechnology, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel
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Moshe A, Gorovits R. Virus-induced aggregates in infected cells. Viruses 2012; 4:2218-32. [PMID: 23202461 PMCID: PMC3497049 DOI: 10.3390/v4102218] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Revised: 09/27/2012] [Accepted: 09/29/2012] [Indexed: 12/21/2022] Open
Abstract
During infection, many viruses induce cellular remodeling, resulting in the formation of insoluble aggregates/inclusions, usually containing viral structural proteins. Identification of aggregates has become a useful diagnostic tool for certain viral infections. There is wide variety of viral aggregates, which differ by their location, size, content and putative function. The role of aggregation in the context of a specific virus is often poorly understood, especially in the case of plant viruses. The aggregates are utilized by viruses to house a large complex of proteins of both viral and host origin to promote virus replication, translation, intra- and intercellular transportation. Aggregated structures may protect viral functional complexes from the cellular degradation machinery. Alternatively, the activation of host defense mechanisms may involve sequestration of virus components in aggregates, followed by their neutralization as toxic for the host cell. The diversity of virus-induced aggregates in mammalian and plant cells is the subject of this review.
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Affiliation(s)
- Adi Moshe
- Institute of Plant Sciences and Genetics in Agriculture and the Otto Warburg Minerva Center for Agricultural Biotechnology, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
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Alcaide-Loridan C, Jupin I. Ubiquitin and plant viruses, let's play together! PLANT PHYSIOLOGY 2012; 160:72-82. [PMID: 22802610 PMCID: PMC3440231 DOI: 10.1104/pp.112.201905] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
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41
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Wrapping membranes around plant virus infection. Curr Opin Virol 2011; 1:388-95. [PMID: 22440840 DOI: 10.1016/j.coviro.2011.09.009] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Revised: 09/25/2011] [Accepted: 09/26/2011] [Indexed: 12/22/2022]
Abstract
Positive strand RNA viruses cause membrane modifications which are microenvironments or larger intracellular compartments, also called 'viroplasms'. These compartments serve to concentrate virus and host factors needed to produce new genomes. Forming these replication sites often involves virus induced membrane synthesis, changes in fatty acid metabolism, and viral recruitment of cellular factors to subcellular domains. Interacting viral and host factors builds the physical scaffold for replication complexes. Such virus induced changes are a visible cytopathology that has been used by plant and mammalian virologists to describe virus disease. This article describes key examples of membrane modifications that are essential for plant virus replication and intercellular transport.
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Jungkunz I, Link K, Vogel F, Voll LM, Sonnewald S, Sonnewald U. AtHsp70-15-deficient Arabidopsis plants are characterized by reduced growth, a constitutive cytosolic protein response and enhanced resistance to TuMV. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2011; 66:983-95. [PMID: 21418353 DOI: 10.1111/j.1365-313x.2011.04558.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Arabidopsis thaliana contains 18 genes encoding Hsp70s. This heat shock protein superfamily is divided into two sub-families: DnaK and Hsp110/SSE. In order to functionally characterize members of the Hsp70 superfamily, loss-of-function mutants with reduced cytosolic Hsp70 expression were studied. AtHsp70-1 and AtHsp70-2 are constitutively expressed and represent the major cytosolic Hsp70 isoforms under ambient conditions. Analysis of single and double mutants did not reveal any difference compared to wild-type controls. In yeast, SSE protein has been shown to act as a nucleotide exchange factor, essential for Hsp70 function. To test whether members of the Hsp110/SSE sub-family serve essential functions in plants, two members of the sub-family, AtHsp70-14 and AtHsp70-15, were analysed. Both genes are highly homologous and constitutively expressed. Deficiency of AtHsp70-15 but not of AtHsp70-14 led to severe growth retardation. AtHsp70-15-deficient plants were smaller than wild-type and exhibited a slightly different leaf shape. Stomatal closure under ambient conditions and in response to ABA was impaired in the AtHsp70-15 transgenic plants, but ABA-dependent inhibition of germination was not affected. Heat treatment of AtHsp70-15-deficient plants resulted in drastically increased mortality, indicating that AtHsp70-15 plays an essential role during normal growth and in the heat response of Arabidopsis plants. AtHsp70-15-deficient plants are more tolerant to infection by turnip mosaic virus. Comparative transcriptome analysis revealed that AtHsp70-15-deficient plants display a constitutive stress response similar to the cytosolic protein response. Based on these results, AtHsp70-15 is likely to be a key factor in proper folding of cytosolic proteins, and may function as nucleotide exchange factor as proposed for yeast.
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Affiliation(s)
- Isabel Jungkunz
- Department of Biology, Friedrich Alexander University Erlangen-Nuremberg, Staudtstrasse 5, 91058 Erlangen, Germany
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Zheng H, Yan F, Lu Y, Sun L, Lin L, Cai L, Hou M, Chen J. Mapping the self-interacting domains of TuMV HC-Pro and the subcellular localization of the protein. Virus Genes 2011; 42:110-6. [PMID: 20938729 DOI: 10.1007/s11262-010-0538-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2010] [Accepted: 09/29/2010] [Indexed: 11/25/2022]
Abstract
The helper component-proteinase (HC-Pro) of potyviruses is a multifunctional protein involved in aphid transmission, polyprotein processing, cell-to-cell and long-distance movement, genome amplification and symptom expression. The HC-Pros of several potyviruses interact with themselves but the key domains responsible for self-interaction are apparently not conserved. In our experiments, yeast two-hybrid assays and bimolecular fluorescence complementation showed that Turnip mosaic virus (TuMV) HC-Pro interacted with itself in yeast cells, plant cells and insect cells. It was also shown that the central and C-terminal regions of the HC-Pro participated in these self-interactions. Fluorescence microscopy showed that TuMV HC-Pro was present in the cytoplasm and formed aggregates along the ER.
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Affiliation(s)
- Hongying Zheng
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, People's Republic of China
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Shemyakina EA, Solovyev AG, Leonova OG, Popenko VI, Schiemann J, Morozov SY. The Role of Microtubule Association in Plasmodesmal Targeting of Potato mop-top virus Movement Protein TGBp1. Open Virol J 2011; 5:1-11. [PMID: 21660184 PMCID: PMC3109696 DOI: 10.2174/1874357901105010001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Revised: 10/11/2010] [Accepted: 10/25/2010] [Indexed: 12/19/2022] Open
Abstract
Cell-to-cell movement of Potato mop-top virus (PMTV) is mediated by three virus-encoded ‘triple gene block’ (TGB) proteins termed TGBp1, TGBp2 and TGBp3. TGBp1 binds virus RNAs to form viral ribonucleoprotein complexes (vRNPs), the transport form of viral genome. TGBp2 and TGBp3 are necessary for intracellular delivery of TGBp1-containing vRNPs to plasmodesmata. To analyze subcellular localization and transport of TGBp1 we used a single binary vector for agrobacterium-mediated co-expression of PMTV TGBp1 fused to green fluorescent protein and TGBp2/TGBp3. At two days post infiltration (dpi) TGBp1 was found in the nucleus and in association with microtubules (MTs). Similar localization pattern was revealed in cells expressing GFP-TGBp1 alone after particle bombardment. At 3 dpi, in addition to the nucleus and MTs, TGBp1 was detected in numerous granular bodies located both along the MTs and at the cell wall. The latter structures co-localized with plasmodesmata-associated callose depositions. At 4 dpi, GFP-TGBp1 was detected in cell wall-associated bodies and also in residual MTs, the nucleoplasm and large perinuclear inclusions resembling aggresomes. Therefore GFP-TGBp1 association with MTs preceded to its localization to plasmodesmata. Disassembly of cell MTs by colchicine prevented GFP-TGBp1 targeting to plasmodesmata and the MT-dependent aggresome formation. Deletion analysis also revealed a correlation between TGBp1 microtubule association and plasmodesmata targeting. We propose that TGBp1 interaction with MTs may be important for the formation of vRNP bodies destined for the transport to plasmodesmata as well as degradation of the excessive TGBp1.
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Affiliation(s)
- Elena A Shemyakina
- Department of Virology, Biological Faculty, Moscow State University, Moscow, 119992, Russia
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Link K, Vogel F, Sonnewald U. PD Trafficking of Potato Leaf Roll Virus Movement Protein in Arabidopsis Depends on Site-specific Protein Phosphorylation. FRONTIERS IN PLANT SCIENCE 2011; 2:18. [PMID: 22645527 PMCID: PMC3355765 DOI: 10.3389/fpls.2011.00018] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Accepted: 05/27/2011] [Indexed: 05/22/2023]
Abstract
Many plant viruses encode for specialized movement proteins (MP) to facilitate passage of viral material to and through plasmodesmata (PD). To analyze intracellular trafficking of potato leaf roll virus (PLRV) movement protein (MP17) we performed GFP fusion experiments with distinct deletion variants of MP17. These studies revealed that the C-terminus of MP17 is essential but not sufficient for PD targeting. Interestingly, fusion of GFP to three C-terminal MP17 deletion variants resulted in the accumulation of GFP in chloroplasts. This indicates that MP17 harbors hidden plastid targeting sequences. Previous studies showed that posttranslational protein phosphorylation influences PD targeting of MP and virus spread. Analysis of MP17-derived phospho-peptides by mass spectrometry revealed four phosphorylated serine residues (S71, S79, S137, and S140). Site-directed mutagenesis of S71/S79 and S137/S140 showed that the C-terminal serine residues S137/S140 are dispensable for PD targeting. However, exchange of S71/S79 to A71/A79 abolished PD targeting of the mutated MP17 protein. To mimic phosphorylation of S71/S79 both amino acids were substituted by aspartic acid. The resulting D71/D79 variant of MP17 was efficiently targeted to PD. Further deletion analysis showed that PD targeting of MP17 is dependent on the C-terminus, phosphorylation of S71 and/or S79 and a N-terminal domain.
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Affiliation(s)
- Katrin Link
- Lehrstuhl für Biochemie, Friedrich-Alexander Universität Erlangen-NürnbergErlangen, Germany
| | - Florian Vogel
- Lehrstuhl für Biochemie, Friedrich-Alexander Universität Erlangen-NürnbergErlangen, Germany
- Environmental Process Engineering, Friedrich-Alexander University Erlangen-Nürnberg Busan CampusBusan, Republic of Korea
| | - Uwe Sonnewald
- Lehrstuhl für Biochemie, Friedrich-Alexander Universität Erlangen-NürnbergErlangen, Germany
- *Correspondence: Uwe Sonnewald, Lehrstuhl für Biochemie, Department Biologie, Staudtstr. 5, 91058 Erlangen, Germany. e-mail:
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Abstract
At only 50 nm in diameter, plasmodesmata (PD) are below the limit of resolution of conventional light microscopy. Consequently, much of our current interpretation of the substructure of PD is derived from transmission electron microscopy. However, PD can be imaged with alternative techniques, including field emission scanning electron microscopy and 'super-resolution' imaging approaches such as 3D-structured illumination microscopy. This review considers the methods currently available for studying PD and focuses on the boundary between light- and electron-based imaging approaches.
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Affiliation(s)
- Karen Bell
- Institute of Molecular Plant Sciences, University of Edinburgh, Mayfield Road, Edinburgh, EH9 3JR, UK
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Jo Y, Cho WK, Rim Y, Moon J, Chen XY, Chu H, Kim CY, Park ZY, Lucas WJ, Kim JY. Plasmodesmal receptor-like kinases identified through analysis of rice cell wall extracted proteins. PROTOPLASMA 2011; 248:191-203. [PMID: 21161304 PMCID: PMC3111878 DOI: 10.1007/s00709-010-0251-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2010] [Accepted: 11/24/2010] [Indexed: 05/06/2023]
Abstract
In plants, plasmodesmata (PD) are intercellular channels that function in both metabolite exchange and the transport of proteins and RNAs. Currently, many of the PD structural and regulatory components remain to be elucidated. Receptor-like kinases (RLKs) belonging to a notably expanded protein family in plants compared to the animal kingdom have been shown to play important roles in plant growth, development, pathogen resistance, and cell death. In this study, cell biological approaches were used to identify potential PD-associated RLK proteins among proteins contained within cell walls isolated from rice callus cultured cells. A total of 15 rice RLKs were investigated to determine their subcellular localization, using an Agrobacterium-mediated transient expression system. Of these six PD-associated RLKs were identified based on their co-localization with a viral movement protein that served as a PD marker, plasmolysis experiments, and subcellular localization at points of wall contact between spongy mesophyll cells. These findings suggest potential PD functions in apoplasmic signaling in response to environmental stimuli and developmental inputs.
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Affiliation(s)
- Yeonhwa Jo
- Division of Applied Life Science (BK21 Program), Environmental Biotechnology National Core Research Center, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, 660-701 Republic of Korea
| | - Won Kyong Cho
- Division of Applied Life Science (BK21 Program), Environmental Biotechnology National Core Research Center, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, 660-701 Republic of Korea
| | - Yeonggil Rim
- Division of Applied Life Science (BK21 Program), Environmental Biotechnology National Core Research Center, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, 660-701 Republic of Korea
| | - Juyeon Moon
- Division of Applied Life Science (BK21 Program), Environmental Biotechnology National Core Research Center, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, 660-701 Republic of Korea
| | - Xiong-Yan Chen
- Division of Applied Life Science (BK21 Program), Environmental Biotechnology National Core Research Center, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, 660-701 Republic of Korea
| | - Hyosub Chu
- Division of Applied Life Science (BK21 Program), Environmental Biotechnology National Core Research Center, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, 660-701 Republic of Korea
- Present Address: Bioindustrial Process Center, Jeonbuk Branch Institute of Korea Research Institute of Bioscience and Biotechnology (KRIBB), Jeonbuk, 580-185 Republic of Korea
| | - Cha Young Kim
- Division of Applied Life Science (BK21 Program), Environmental Biotechnology National Core Research Center, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, 660-701 Republic of Korea
- Present Address: Bioindustrial Process Center, Jeonbuk Branch Institute of Korea Research Institute of Bioscience and Biotechnology (KRIBB), Jeonbuk, 580-185 Republic of Korea
| | - Zee-Yong Park
- Department of Life Science, Gwangju Institute of Science and Technology, Gwangju, 500-712 Republic of Korea
| | - William J. Lucas
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA 95616 USA
| | - Jae-Yean Kim
- Division of Applied Life Science (BK21 Program), Environmental Biotechnology National Core Research Center, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, 660-701 Republic of Korea
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Vogel F, Hofius D, Paulus KE, Jungkunz I, Sonnewald U. The second face of a known player: Arabidopsis silencing suppressor AtXRN4 acts organ-specifically. THE NEW PHYTOLOGIST 2011; 189:484-493. [PMID: 21039560 DOI: 10.1111/j.1469-8137.2010.03482.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Plant viruses exploit the symplastic transport pathway provided by plasmodesmata by encoding for specialized movement proteins, which interact with host factors to enable viral intracellular and intercellular spread. Stable expression of the Potato leaf roll virus movement protein MP17 in Arabidopsis results in a carbohydrate export block and stunted growth. To identify host factors essential for viral infection, we screened a progeny population of EMS (ethyl methanesulfonate)-mutagenized Arabidopsis expressing a MP17:GFP fusion for suppressor mutants with restored wild type-like phenotype. Two suppressor mutants showed decreased susceptibility against Turnip mosaic virus and post-transcriptional silencing of MP17:GFP RNA in source leaves. Map based cloning identified in both lines mutations in XRN4 (Exoribonuclease 4), which was previously described as a suppressor of transgene silencing in source leaves. Importantly, silencing of MP17:GFP was not present in cotyledons and roots of the two suppressor mutants, which was confirmed in a third xrn4 T-DNA knock out line. Subsequent analysis of MP17:GFP transcript stability in xrn2 and xrn3 mutants indicated an essential role of AtXRN2 for silencing suppression in roots/cotyledons while AtXRN3 appears to act similar to AtXRN4 in source leaves, only. Overall, these findings point towards an organ-specific regulation of gene silencing in Arabidopsis.
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Affiliation(s)
- Florian Vogel
- Friedrich-Alexander Universität Erlangen-Nürnberg, Staudtstrasse 5, D-91058 Erlangen Germany.
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49
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Werner D, Gerlitz N, Stadler R. A dual switch in phloem unloading during ovule development in Arabidopsis. PROTOPLASMA 2011; 248:225-35. [PMID: 21153670 DOI: 10.1007/s00709-010-0223-8] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Accepted: 10/12/2010] [Indexed: 05/18/2023]
Abstract
Developing flowers are important sinks in Arabidopsis thaliana. Their energy demand is covered by assimilates which are synthesized in source leaves and transported via the vasculature. Assimilates are unloaded either symplastically through plasmodesmata or apoplastically by specific transport proteins. Here we studied the pathway of phloem unloading and post-phloem transport in developing gynoecia. Using phloem-mobile fluorescent tracers, we show that phloem unloading into cells of ovule primordia followed a symplastic pathway. Subsequently, the same tracers could not move out of phloem cells into mature ovules anymore. A further change in the mode of phloem unloading occurred after anthesis. In open flowers as well as in outgrowing siliques, the phloem was again unloaded via the symplast. This observed onset of symplastic phloem unloading was accompanied by a change in frequency of MP17-GFP-labeled plasmodesmata. We could also show that the change in cell-cell connectivity was independent of fertilization and increasing sink demand. The presented results indicate that symplastic connectivity is highly regulated and varies not only between different sink tissues but also between different developmental stages.
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Affiliation(s)
- Dagmar Werner
- Lehrstuhl Molekulare Pflanzenphysiologie, Universität Erlangen-Nürnberg, Staudtstrasse 5, 91058, Erlangen, Germany
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50
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Niehl A, Heinlein M. Cellular pathways for viral transport through plasmodesmata. PROTOPLASMA 2011; 248:75-99. [PMID: 21125301 DOI: 10.1007/s00709-010-0246-1] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2010] [Accepted: 11/16/2010] [Indexed: 05/03/2023]
Abstract
Plant viruses use plasmodesmata (PD) to spread infection between cells and systemically. Dependent on viral species, movement through PD can occur in virion or non-virion form, and requires different mechanisms for targeting and modification of the pore. These mechanisms are supported by viral movement proteins and by other virus-encoded factors that interact among themselves and with plant cellular components to facilitate virus movement in a coordinated and regulated fashion.
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Affiliation(s)
- Annette Niehl
- Institut de Biologie Moléculaire des Plantes du CNRS, Université de Strasbourg, 12 rue du Général Zimmer, 67084, Strasbourg, France
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