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Fujiwara MT, Yoshioka Y, Kazama Y, Hirano T, Niwa Y, Moriyama T, Sato N, Abe T, Yoshida S, Itoh RD. Principles of amyloplast replication in the ovule integuments of Arabidopsis thaliana. PLANT PHYSIOLOGY 2024; 196:137-152. [PMID: 38829834 DOI: 10.1093/plphys/kiae314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 04/30/2024] [Accepted: 05/01/2024] [Indexed: 06/05/2024]
Abstract
Plastids in vascular plants have various differentiated forms, among which amyloplasts are crucial for starch storage and plant productivity. Despite the vast knowledge of the binary-fission mode of chloroplast division, our understanding of the replication of non-photosynthetic plastids, including amyloplasts, remains limited. Recent studies have suggested the involvement of stromules (stroma-filled tubules) in plastid replication when the division apparatus is faulty. However, details of the underlying mechanism(s) and their relevance to normal processes have yet to be elucidated. Here, we developed a live analysis system for studying amyloplast replication using Arabidopsis (Arabidopsis thaliana) ovule integuments. We showed the full sequence of amyloplast development and demonstrated that wild-type amyloplasts adopt three modes of replication, binary fission, multiple fission, and stromule-mediated fission, via multi-way placement of the FtsZ ring. The minE mutant, with severely inhibited chloroplast division, showed marked heterogeneity in amyloplast size, caused by size-dependent but wild-type modes of plastid fission. The dynamic properties of stromules distinguish the wild-type and minE phenotypes. In minE cells, extended stromules from giant amyloplasts acquired stability, allowing FtsZ ring assembly and constriction, as well as the growth of starch grains therein. Despite hyper-stromule formation, amyloplasts did not proliferate in the ftsZ null mutant. These data clarify the differences between amyloplast and chloroplast replication and demonstrate that the structural plasticity of amyloplasts underlies the multiplicity of their replication processes. Furthermore, this study shows that stromules can generate daughter plastids via the assembly of the FtsZ ring.
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Affiliation(s)
- Makoto T Fujiwara
- Nishina Center and Plant Functions Laboratory (Disbanded in March 2004), RIKEN, Wako, Saitama 351-0198, Japan
- Department of Biology, Graduate School of Science and Technology, Sophia University, Kioicho, Chiyoda 102-8554, Japan
- College of Arts and Sciences, University of Tokyo, Komaba, Tokyo 153-8902, Japan
| | - Yasushi Yoshioka
- Graduate School of Science, Nagoya University, Furo-cho, Nagoya 464-8602, Japan
| | - Yusuke Kazama
- Nishina Center and Plant Functions Laboratory (Disbanded in March 2004), RIKEN, Wako, Saitama 351-0198, Japan
| | - Tomonari Hirano
- Nishina Center and Plant Functions Laboratory (Disbanded in March 2004), RIKEN, Wako, Saitama 351-0198, Japan
| | - Yasuo Niwa
- Laboratory of Plant Cell Technology, University of Shizuoka, Yada, Shizuoka 422-8526, Japan
| | - Takashi Moriyama
- College of Arts and Sciences, University of Tokyo, Komaba, Tokyo 153-8902, Japan
| | - Naoki Sato
- College of Arts and Sciences, University of Tokyo, Komaba, Tokyo 153-8902, Japan
| | - Tomoko Abe
- Nishina Center and Plant Functions Laboratory (Disbanded in March 2004), RIKEN, Wako, Saitama 351-0198, Japan
| | - Shigeo Yoshida
- Nishina Center and Plant Functions Laboratory (Disbanded in March 2004), RIKEN, Wako, Saitama 351-0198, Japan
| | - Ryuuichi D Itoh
- Department of Chemistry, Biology and Marine Science, Faculty of Science, University of the Ryukyus, Senbaru 1, Nishihara, Okinawa 903-0213, Japan
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2
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Jung S, Woo J, Park E. Talk to your neighbors in an emergency: Stromule-mediated chloroplast-nucleus communication in plant immunity. CURRENT OPINION IN PLANT BIOLOGY 2024; 79:102529. [PMID: 38604000 DOI: 10.1016/j.pbi.2024.102529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 03/08/2024] [Accepted: 03/19/2024] [Indexed: 04/13/2024]
Abstract
Hypersensitive response-programmed cell death (HR-PCD) is a response mounted by plants to defend themselves against pathogens. Communication between the chloroplast and the nucleus is critical for the progression of HR-PCD. Tubular protrusions of chloroplasts, known as stromules, are tightly associated with the HR-PCD progression. There is emerging evidence that signaling molecules originating from chloroplasts are transferred to the nucleus through stromules. The translocation of signaling molecules from the chloroplast to the nucleus might trigger defense responses, including transcriptional reprogramming. In this review, we discuss the possible functions of stromules in the rapid transfer of signaling molecules in the chloroplast-nucleus communication.
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Affiliation(s)
- Seungmee Jung
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA
| | - Jongchan Woo
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA
| | - Eunsook Park
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA.
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3
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Letanneur C, Brisson A, Bisaillon M, Devèze T, Plourde MB, Schattat M, Duplessis S, Germain H. Host-Specific and Homologous Pairs of Melampsora larici-populina Effectors Unveil Novel Nicotiana benthamiana Stromule Induction Factors. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2024; 37:277-289. [PMID: 38148279 DOI: 10.1094/mpmi-09-23-0148-fi] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2023]
Abstract
The poplar rust fungus Melampsora larici-populina is part of one of the most devastating group of fungi (Pucciniales) and causes important economic losses to the poplar industry. Because M. larici-populina is a heteroecious obligate biotroph, its spread depends on its ability to carry out its reproductive cycle through larch and then poplar parasitism. Genomic approaches have identified more than 1,000 candidate secreted effector proteins (CSEPs) from the predicted secretome of M. larici-populina that are potentially implicated in the infection process. In this study, we selected CSEP pairs (and one triplet) among CSEP gene families that share high sequence homology but display specific gene expression profiles among the two distinct hosts. We determined their subcellular localization by confocal microscopy through expression in the heterologous plant system Nicotiana benthamiana. Five out of nine showed partial or complete chloroplastic localization. We also screened for potential protein interactors from larch and poplar by yeast two-hybrid assays. One pair of CSEPs and the triplet shared common interactors, whereas the members of the two other pairs did not have common targets from either host. Finally, stromule induction quantification revealed that two pairs and the triplet of CSEPs induced stromules when transiently expressed in N. benthamiana. The use of N. benthamiana eds1 and nrg1 knockout lines showed that CSEPs can induce stromules through an eds1-independent mechanism. However, CSEP homologs shared the same impact on stromule induction and contributed to discovering a new stromule induction cascade that can be partially and/or fully independent of eds1. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Claire Letanneur
- Chemistry, Biochemistry, and Physics Department, Université du Québec à Trois-Rivières, Trois-Rivières, G8Z 4M3, Canada
| | - Alexandre Brisson
- Chemistry, Biochemistry, and Physics Department, Université du Québec à Trois-Rivières, Trois-Rivières, G8Z 4M3, Canada
| | - Mathias Bisaillon
- Chemistry, Biochemistry, and Physics Department, Université du Québec à Trois-Rivières, Trois-Rivières, G8Z 4M3, Canada
| | - Théo Devèze
- Chemistry, Biochemistry, and Physics Department, Université du Québec à Trois-Rivières, Trois-Rivières, G8Z 4M3, Canada
| | - Mélodie B Plourde
- Chemistry, Biochemistry, and Physics Department, Université du Québec à Trois-Rivières, Trois-Rivières, G8Z 4M3, Canada
| | - Martin Schattat
- Plant Physiology Department, Martin Luther University, 06120 Halle, Germany
| | | | - Hugo Germain
- Chemistry, Biochemistry, and Physics Department, Université du Québec à Trois-Rivières, Trois-Rivières, G8Z 4M3, Canada
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4
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Mathur J, Kunjumon TK, Mammone A, Mathur N. Membrane contacts with the endoplasmic reticulum modulate plastid morphology and behaviour. FRONTIERS IN PLANT SCIENCE 2023; 14:1293906. [PMID: 38111880 PMCID: PMC10726010 DOI: 10.3389/fpls.2023.1293906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 11/20/2023] [Indexed: 12/20/2023]
Abstract
Plastid behaviour often occurs in tandem with endoplasmic reticulum (ER) dynamics. In order to understand the underlying basis for such linked behaviour we have used time-lapse imaging-based analysis of plastid movement and pleomorphy, including the extension and retraction of stromules. Stable transgenic plants that simultaneously express fluorescent fusion proteins targeted to the plastid stroma, and the ER along with BnCLIP1-eGFP, an independent plastid envelope localized membrane contact site (MCS) marker were utilized. Our experiments strongly suggest that transient MCS formed between the plastid envelope and the ER are responsible for their concomitant behaviour.
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Affiliation(s)
- Jaideep Mathur
- Laboratory of Plant Development and Interactions, Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
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5
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Frangedakis E, Marron AO, Waller M, Neubauer A, Tse SW, Yue Y, Ruaud S, Waser L, Sakakibara K, Szövényi P. What can hornworts teach us? FRONTIERS IN PLANT SCIENCE 2023; 14:1108027. [PMID: 36968370 PMCID: PMC10030945 DOI: 10.3389/fpls.2023.1108027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Accepted: 02/13/2023] [Indexed: 06/18/2023]
Abstract
The hornworts are a small group of land plants, consisting of only 11 families and approximately 220 species. Despite their small size as a group, their phylogenetic position and unique biology are of great importance. Hornworts, together with mosses and liverworts, form the monophyletic group of bryophytes that is sister to all other land plants (Tracheophytes). It is only recently that hornworts became amenable to experimental investigation with the establishment of Anthoceros agrestis as a model system. In this perspective, we summarize the recent advances in the development of A. agrestis as an experimental system and compare it with other plant model systems. We also discuss how A. agrestis can help to further research in comparative developmental studies across land plants and to solve key questions of plant biology associated with the colonization of the terrestrial environment. Finally, we explore the significance of A. agrestis in crop improvement and synthetic biology applications in general.
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Affiliation(s)
| | - Alan O. Marron
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
| | - Manuel Waller
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
- Zurich-Basel Plant Science Center, Zurich, Switzerland
| | - Anna Neubauer
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
- Zurich-Basel Plant Science Center, Zurich, Switzerland
| | - Sze Wai Tse
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
| | - Yuling Yue
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
- Zurich-Basel Plant Science Center, Zurich, Switzerland
| | - Stephanie Ruaud
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
- Zurich-Basel Plant Science Center, Zurich, Switzerland
| | - Lucas Waser
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
- Zurich-Basel Plant Science Center, Zurich, Switzerland
- Department of Plant and Microbial Biology, University of Zürich, Zurich, Switzerland
| | | | - Péter Szövényi
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
- Zurich-Basel Plant Science Center, Zurich, Switzerland
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6
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Yanagisawa M, Chuong SDX. Chloroplast Envelopes Play a Role in the Formation of Autophagy-Related Structures in Plants. PLANTS (BASEL, SWITZERLAND) 2023; 12:443. [PMID: 36771525 PMCID: PMC9920391 DOI: 10.3390/plants12030443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 01/12/2023] [Accepted: 01/16/2023] [Indexed: 06/18/2023]
Abstract
Autophagy is a degradation process of cytoplasmic components that is conserved in eukaryotes. One of the hallmark features of autophagy is the formation of double-membrane structures known as autophagosomes, which enclose cytoplasmic content destined for degradation. Although the membrane source for the formation of autophagosomes remains to be determined, recent studies indicate the involvement of various organelles in autophagosome biogenesis. In this study, we examined the autophagy process in Bienertia sinuspersici: one of four terrestrial plants capable of performing C4 photosynthesis in a single cell (single-cell C4 species). We demonstrated that narrow tubules (stromule-like structures) 30-50 nm in diameter appear to extend from chloroplasts to form the membrane-bound structures (autophagosomes or autophagy-related structures) in chlorenchyma cells of B. sinuspersici during senescence and under oxidative stress. Immunoelectron microscopic analysis revealed the localization of stromal proteins to the stromule-like structures, sequestering portions of the cytoplasm in chlorenchyma cells of oxidative stress-treated leaves of B. sinuspersici and Arabidopsis thaliana. Moreover, the fluorescent marker for autophagosomes GFP-ATG8, colocalized with the autophagic vacuole maker neutral red in punctate structures in close proximity to the chloroplasts of cells under oxidative stress conditions. Together our results implicate a role for chloroplast envelopes in the autophagy process induced during senescence or under certain stress conditions in plants.
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7
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Prautsch J, Erickson JL, Özyürek S, Gormanns R, Franke L, Lu Y, Marx J, Niemeyer F, Parker JE, Stuttmann J, Schattat MH. Effector XopQ-induced stromule formation in Nicotiana benthamiana depends on ETI signaling components ADR1 and NRG1. PLANT PHYSIOLOGY 2023; 191:161-176. [PMID: 36259930 PMCID: PMC9806647 DOI: 10.1093/plphys/kiac481] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 09/22/2022] [Indexed: 05/28/2023]
Abstract
In Nicotiana benthamiana, the expression of the Xanthomonas effector XANTHOMONAS OUTER PROTEIN Q (XopQ) triggers RECOGNITION OF XOPQ1 (ROQ1)-dependent effector-triggered immunity (ETI) responses accompanied by the accumulation of plastids around the nucleus and the formation of stromules. Both plastid clustering and stromules were proposed to contribute to ETI-related hypersensitive cell death and thereby to plant immunity. Whether these reactions are directly connected to ETI signaling events has not been tested. Here, we utilized transient expression experiments to determine whether XopQ-triggered plastid reactions are a result of XopQ perception by the immune receptor ROQ1 or a consequence of XopQ virulence activity. We found that N. benthamiana mutants lacking ROQ1, ENHANCED DISEASE SUSCEPTIBILITY 1, or the helper NUCLEOTIDE-BINDING LEUCINE-RICH REPEAT IMMUNE RECEPTORS (NLRs) N-REQUIRED GENE 1 (NRG1) and ACTIVATED DISEASE RESISTANCE GENE 1 (ADR1), fail to elicit XopQ-dependent host cell death and stromule formation. Mutants lacking only NRG1 lost XopQ-dependent cell death but retained some stromule induction that was abolished in the nrg1_adr1 double mutant. This analysis aligns XopQ-triggered stromules with the ETI signaling cascade but not to host programmed cell death. Furthermore, data reveal that XopQ-triggered plastid clustering is not strictly linked to stromule formation during ETI. Our data suggest that stromule formation, in contrast to chloroplast perinuclear dynamics, is an integral part of the N. benthamiana ETI response and that both NRG1 and ADR1 hNLRs play a role in this ETI response.
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Affiliation(s)
- Jennifer Prautsch
- Biology, Plant Physiology, Martin-Luther-University Halle-Wittenberg, Halle, Germany
| | - Jessica Lee Erickson
- Biology, Plant Genetics, Martin-Luther-University Halle-Wittenberg, Halle, Germany
- Leibniz-Institut for Plant Biochemistry, Halle, Germany
| | - Sedef Özyürek
- Biology, Plant Physiology, Martin-Luther-University Halle-Wittenberg, Halle, Germany
| | - Rahel Gormanns
- Biology, Plant Physiology, Martin-Luther-University Halle-Wittenberg, Halle, Germany
| | - Lars Franke
- Biochemistry and Biotechnology, Martin-Luther-University Halle-Wittenberg, Halle, Germany
| | - Yang Lu
- Biology, Plant Physiology, Martin-Luther-University Halle-Wittenberg, Halle, Germany
| | - Jolina Marx
- Leibniz-Institut for Plant Biochemistry, Halle, Germany
| | - Frederik Niemeyer
- Biology, Plant Physiology, Martin-Luther-University Halle-Wittenberg, Halle, Germany
| | - Jane E Parker
- Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Johannes Stuttmann
- Biology, Plant Genetics, Martin-Luther-University Halle-Wittenberg, Halle, Germany
- Institute for Biosafety in Plant Biotechnology, Federal Research Centre for Cultivated Plants, Julius Kühn-Institute (JKI), Quedlinburg, Germany
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8
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Mackenzie SA, Mullineaux PM. Plant environmental sensing relies on specialized plastids. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:7155-7164. [PMID: 35994779 DOI: 10.1093/jxb/erac334] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 08/22/2022] [Indexed: 06/15/2023]
Abstract
In plants, plastids are thought to interconvert to various forms that are specialized for photosynthesis, starch and oil storage, and diverse pigment accumulation. Post-endosymbiotic evolution has led to adaptations and specializations within plastid populations that align organellar functions with different cellular properties in primary and secondary metabolism, plant growth, organ development, and environmental sensing. Here, we review the plastid biology literature in light of recent reports supporting a class of 'sensory plastids' that are specialized for stress sensing and signaling. Abundant literature indicates that epidermal and vascular parenchyma plastids display shared features of dynamic morphology, proteome composition, and plastid-nuclear interaction that facilitate environmental sensing and signaling. These findings have the potential to reshape our understanding of plastid functional diversification.
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Affiliation(s)
- Sally A Mackenzie
- Departments of Biology and Plant Science, The Pennsylvania State University, University Park, PA 16802, USA
| | - Philip M Mullineaux
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, Essex CO4 3SQ, UK
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9
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Mathur J, Kroeker OF, Lobbezoo M, Mathur N. The ER Is a Common Mediator for the Behavior and Interactions of Other Organelles. FRONTIERS IN PLANT SCIENCE 2022; 13:846970. [PMID: 35401583 PMCID: PMC8990311 DOI: 10.3389/fpls.2022.846970] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Accepted: 03/02/2022] [Indexed: 05/29/2023]
Abstract
Optimal functioning of a plant cell depends upon the efficient exchange of genetic information, ions, proteins and metabolites between the different organelles. Intuitively, increased proximity between organelles would be expected to play an important role in facilitating exchanges between them. However, it remains to be seen whether under normal, relatively non-stressed conditions organelles maintain close proximity at all. Moreover, does interactivity involve direct and frequent physical contact between the different organelles? Further, many organelles transition between spherical and tubular forms or sporadically produce thin tubular extensions, but it remains unclear whether changes in organelle morphology play a role in increasing their interactivity. Here, using targeted multicolored fluorescent fusion proteins, we report observations on the spatiotemporal relationship between plastids, mitochondria, peroxisomes and the endoplasmic reticulum in living plant cells. Under normal conditions of growth, we observe that the smaller organelles do not establish direct, physical contacts with each other but, irrespective of their individual form they all maintain intimate connectivity with the ER. Proximity between organelles does increase in response to stress through concomitant alterations in ER dynamics. Significantly, even under increased proximity the ER still remains sandwiched between the different organelles. Our observations provide strong live-imaging-based evidence for the ER acting as a common mediator in interactions between other organelles.
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10
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Ishida H, Okashita Y, Ishida H, Hayashi M, Izumi M, Makino A, Bhuiyan NH, van Wijk KJ. GFS9 Affects Piecemeal Autophagy of Plastids in Young Seedlings of Arabidopsis thaliana. PLANT & CELL PHYSIOLOGY 2021; 62:1372-1386. [PMID: 34086965 DOI: 10.1093/pcp/pcab084] [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: 09/15/2020] [Revised: 05/26/2021] [Accepted: 06/04/2021] [Indexed: 06/12/2023]
Abstract
Chloroplasts, and plastids in general, contain abundant protein pools that can be major sources of carbon and nitrogen for recycling. We have previously shown that chloroplasts are partially and sequentially degraded by piecemeal autophagy via the Rubisco-containing body. This degradation occurs during plant development and in response to the environment; however, little is known about the fundamental underlying mechanisms. To discover the mechanisms of piecemeal autophagy of chloroplasts/plastids, we conducted a forward-genetics screen following ethyl-methanesulfonate mutagenesis of an Arabidopsis (Arabidopsis thaliana) transgenic line expressing chloroplast-targeted green fluorescent protein (CT-GFP). This screen allowed us to isolate a mutant, gfs9-5, which hyperaccumulated cytoplasmic bodies labeled with CT-GFP of up to 1.0 μm in diameter in the young seedlings. We termed these structures plastid bodies (PBs). The mutant was defective in a membrane-trafficking factor, green fluorescent seed 9 (GFS9), and PB accumulation in gfs9-5 was promoted by darkness and nutrient deficiency. Transmission electron microscopy indicated that gfs9-5 hyperaccumulated structures corresponding to autophagosomes and PBs. gfs9-5 hyperaccumulated membrane-bound endogenous ATG8 proteins, transgenic yellow fluorescent protein (YFP)-ATG8e proteins and autophagosome-like structures labeled with YFP-ATG8e. The YFP-ATG8e signal was associated with the surface of plastids and their protrusions in gfs9-5. Double mutants of gfs9 and autophagy-defective 5 did not accumulate PBs. In gfs9-5, the YFP-ATG8e proteins and PBs could be delivered to the vacuole and autophagic flux was increased. We discuss a possible connection between GFS9 and autophagy and propose a potential use of gfs9-5 as a new tool to study piecemeal plastid autophagy.
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Affiliation(s)
- Hiroyuki Ishida
- Department of Applied Plant Science, Graduate School of Agricultural Science, Tohoku University, 468-1 Aramaki Aza Aoba, Sendai 980-8572, Japan
- School of Integrative Plant Sciences, Section of Plant Biology, Cornell University, Ithaca, NY 14853, USA
| | - Yu Okashita
- Department of Applied Plant Science, Graduate School of Agricultural Science, Tohoku University, 468-1 Aramaki Aza Aoba, Sendai 980-8572, Japan
| | - Hiromi Ishida
- Department of Applied Plant Science, Graduate School of Agricultural Science, Tohoku University, 468-1 Aramaki Aza Aoba, Sendai 980-8572, Japan
- School of Integrative Plant Sciences, Section of Plant Biology, Cornell University, Ithaca, NY 14853, USA
| | - Makoto Hayashi
- Department of Bioscience, Nagahama Institute of Bioscience and Technology, Tamura 1266, Nagahama, Shiga 526-0829, Japan
| | - Masanori Izumi
- Center for Sustainable Resource Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Amane Makino
- Department of Applied Plant Science, Graduate School of Agricultural Science, Tohoku University, 468-1 Aramaki Aza Aoba, Sendai 980-8572, Japan
| | - Nazmul H Bhuiyan
- School of Integrative Plant Sciences, Section of Plant Biology, Cornell University, Ithaca, NY 14853, USA
- Eurofins Lancaster Lab PSS, Richmond, VA, USA
| | - Klaas J van Wijk
- School of Integrative Plant Sciences, Section of Plant Biology, Cornell University, Ithaca, NY 14853, USA
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11
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Lichtscheidl I, Lancelle S, Weidinger M, Adlassnig W, Koller-Peroutka M, Bauer S, Krammer S, Hepler PK. Gland cell responses to feeding in Drosera capensis, a carnivorous plant. PROTOPLASMA 2021; 258:1291-1306. [PMID: 34155556 PMCID: PMC8523503 DOI: 10.1007/s00709-021-01667-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 05/11/2021] [Indexed: 05/08/2023]
Abstract
Glands of Drosera absorb and transport nutrients from captured prey, but the mechanism and dynamics remain unclear. In this study, we offered animal proteins in the form of fluorescent albumin (FITC-BSA) and observed the reactions of the glands by live cell imaging and fluorescence microscopy. The ultrastructure of these highly dynamic processes was also assessed in high-pressure frozen and freeze substituted (HPF-FS) cells. HPF-FS yielded excellent preservation of the cytoplasm of all cell types, although the cytosol looked different in gland cells as compared to endodermoid and stalk cells. Especially prominent were the ER and its contacts with the plasma membrane, plasmodesmata, and other organelles as well as continuities between organelles. Also distinct were actin microfilaments in association with ER and organelles. Application of FITC-BSA to glands caused the formation of fluorescent endosomes that pinched off the plasma membrane. Endosomes fused to larger aggregates, and accumulated in the bulk cytoplasm around the nucleus. They did not fuse with the cell sap vacuole but remained for at least three days; in addition, fluorescent vesicles also proceeded through endodermoid and transfer cells to the epidermal and parenchymal cells of the tentacle stalk.
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Affiliation(s)
- Irene Lichtscheidl
- Cell Imaging and Ultrastructure Research, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
| | - Sue Lancelle
- Biology Department, University of Massachusetts Amherst, 221 Morrill Science Center III; 611 North Pleasant Street, Amherst, MA 01003-9297 USA
| | - Marieluise Weidinger
- Cell Imaging and Ultrastructure Research, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
| | - Wolfram Adlassnig
- Cell Imaging and Ultrastructure Research, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
| | - Marianne Koller-Peroutka
- Cell Imaging and Ultrastructure Research, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
| | - Sonja Bauer
- Cell Imaging and Ultrastructure Research, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
| | - Stefanie Krammer
- Cell Imaging and Ultrastructure Research, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
| | - Peter K. Hepler
- Biology Department, University of Massachusetts Amherst, 221 Morrill Science Center III; 611 North Pleasant Street, Amherst, MA 01003-9297 USA
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12
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Itoh RD, Nakajima KP, Sasaki S, Ishikawa H, Kazama Y, Abe T, Fujiwara MT. TGD5 is required for normal morphogenesis of non-mesophyll plastids, but not mesophyll chloroplasts, in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 107:237-255. [PMID: 33884686 DOI: 10.1111/tpj.15287] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 04/10/2021] [Accepted: 04/13/2021] [Indexed: 06/12/2023]
Abstract
Stromules are dynamic membrane-bound tubular structures that emanate from plastids. Stromule formation is triggered in response to various stresses and during plant development, suggesting that stromules may have physiological and developmental roles in these processes. Despite the possible biological importance of stromules and their prevalence in green plants, their exact roles and formation mechanisms remain unclear. To explore these issues, we obtained Arabidopsis thaliana mutants with excess stromule formation in the leaf epidermis by microscopy-based screening. Here, we characterized one of these mutants, stromule biogenesis altered 1 (suba1). suba1 forms plastids with severely altered morphology in a variety of non-mesophyll tissues, such as leaf epidermis, hypocotyl epidermis, floral tissues, and pollen grains, but apparently normal leaf mesophyll chloroplasts. The suba1 mutation causes impaired chloroplast pigmentation and altered chloroplast ultrastructure in stomatal guard cells, as well as the aberrant accumulation of lipid droplets and their autophagic engulfment by the vacuole. The causal defective gene in suba1 is TRIGALACTOSYLDIACYLGLYCEROL5 (TGD5), which encodes a protein putatively involved in the endoplasmic reticulum (ER)-to-plastid lipid trafficking required for the ER pathway of thylakoid lipid assembly. These findings suggest that a non-mesophyll-specific mechanism maintains plastid morphology. The distinct mechanisms maintaining plastid morphology in mesophyll versus non-mesophyll plastids might be attributable, at least in part, to the differential contributions of the plastidial and ER pathways of lipid metabolism between mesophyll and non-mesophyll plastids.
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Affiliation(s)
- Ryuuichi D Itoh
- Department of Chemistry, Biology and Marine Science, Faculty of Science, University of the Ryukyus, Senbaru 1, Nishihara, Okinawa, 903-0213, Japan
| | - Kohdai P Nakajima
- Department of Chemistry, Biology and Marine Science, Faculty of Science, University of the Ryukyus, Senbaru 1, Nishihara, Okinawa, 903-0213, Japan
| | - Shun Sasaki
- Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, 7-1 Kioicho, Chiyoda, Tokyo, 102-8554, Japan
| | - Hiroki Ishikawa
- Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, 7-1 Kioicho, Chiyoda, Tokyo, 102-8554, Japan
| | - Yusuke Kazama
- Nishina Center, RIKEN, Wako, Saitama, 351-0198, Japan
| | - Tomoko Abe
- Nishina Center, RIKEN, Wako, Saitama, 351-0198, Japan
| | - Makoto T Fujiwara
- Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, 7-1 Kioicho, Chiyoda, Tokyo, 102-8554, Japan
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13
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Mathur J. Organelle extensions in plant cells. PLANT PHYSIOLOGY 2021; 185:593-607. [PMID: 33793902 PMCID: PMC8133556 DOI: 10.1093/plphys/kiaa055] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 09/15/2020] [Indexed: 05/03/2023]
Abstract
The life strategy of plants includes their ability to respond quickly at the cellular level to changes in their environment. The use of targeted fluorescent protein probes and imaging of living cells has revealed several rapidly induced organelle responses that create the efficient sub-cellular machinery for maintaining homeostasis in the plant cell. Several organelles, including plastids, mitochondria, and peroxisomes, extend and retract thin tubules that have been named stromules, matrixules, and peroxules, respectively. Here, I combine all these thin tubular forms under the common head of organelle extensions. All extensions change shape continuously and in their elongated form considerably increase organelle outreach into the surrounding cytoplasm. Their pleomorphy reflects their interactions with the dynamic endoplasmic reticulum and cytoskeletal elements. Here, using foundational images and time-lapse movies, and providing salient information on some molecular and biochemically characterized mutants with increased organelle extensions, I draw attention to their common role in maintaining homeostasis in plant cells.
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Affiliation(s)
- Jaideep Mathur
- Laboratory of Plant Development and Interactions, Department of Molecular and Cellular biology, University of Guelph, 50 Stone Road, Guelph, Ontario, N1G2W1 Canada
- Author for communication:
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14
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Hanson MR, Conklin PL. Stromules, functional extensions of plastids within the plant cell. CURRENT OPINION IN PLANT BIOLOGY 2020; 58:25-32. [PMID: 33137706 DOI: 10.1016/j.pbi.2020.10.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 10/11/2020] [Accepted: 10/12/2020] [Indexed: 06/11/2023]
Abstract
Stromules are thin tubular extensions of the plastid compartment surrounded by the envelope membrane. A myriad of functions have been proposed for them, and they likely have multiple roles. Recent work has illuminated aspects of their formation, especially the important of microtubules in their movement and microfilaments in anchoring. A variety of biotic and abiotic stresses result in induction of stromule formation, and in recent years, stromule formation has been strongly implicated as part of the innate immune response. Both stromules and chloroplasts relocate to surround the nucleus when pathogens are sensed, possibly to supply signaling molecules such as reactive oxygen species. In addition to the nucleus, stromules have been observed in close proximity to other compartments such as mitochondria, endoplasmic reticulum, and the plasma membrane, potentially facilitating exchange of substrates and products to carry out important biosynthetic pathways. Much remains to be learned about the identity of proteins and other molecules released from chloroplasts and stromules and how they function in plant development and defense.
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Affiliation(s)
- Maureen R Hanson
- Department of Molecular Biology and Genetics, Biotechnology Building, Cornell University, Ithaca, NY 14853, USA.
| | - Patricia L Conklin
- Biological Sciences Department, State University of New York, Cortland, NY 13045, USA
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15
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Ishikawa H, Yasuzawa M, Koike N, Sanjaya A, Moriyama S, Nishizawa A, Matsuoka K, Sasaki S, Kazama Y, Hayashi Y, Abe T, Fujiwara MT, Itoh RD. Arabidopsis PARC6 Is Critical for Plastid Morphogenesis in Pavement, Trichome, and Guard Cells in Leaf Epidermis. FRONTIERS IN PLANT SCIENCE 2019; 10:1665. [PMID: 32010156 PMCID: PMC6974557 DOI: 10.3389/fpls.2019.01665] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2019] [Accepted: 11/26/2019] [Indexed: 05/20/2023]
Abstract
Recently, a recessive Arabidopsis thaliana mutant with abundant stromules in leaf epidermal pavement cells was visually screened and isolated. The gene responsible for this mutant phenotype was identified as PARC6, a chloroplast division site regulator gene. The mutant allele parc6-5 carried two point mutations (G62R and W700stop) at the N- and C-terminal ends of the coding sequence, respectively. Here, we further characterized parc6-5 and other parc6 mutant alleles, and showed that PARC6 plays a critical role in plastid morphogenesis in all cell types of the leaf epidermis: pavement cells, trichome cells, and guard cells. Transient expression of PARC6 transit peptide (TP) fused to the green fluorescent protein (GFP) in plant cells showed that the G62R mutation has no or little effect on the TP activity of the PARC6 N-terminal region. Then, plastid morphology was microscopically analyzed in the leaf epidermis of wild-type (WT) and parc6 mutants (parc6-1, parc6-3, parc6-4 and parc6-5) with the aid of stroma-targeted fluorescent proteins. In parc6 pavement cells, plastids often assumed aberrant grape-like morphology, similar to those in severe plastid division mutants, atminE1, and arc6. In parc6 trichome cells, plastids exhibited extreme grape-like aggregations, without the production of giant plastids (>6 µm diameter), as a general phenotype. In parc6 guard cells, plastids exhibited a variety of abnormal phenotypes, including reduced number, enlarged size, and activated stromules, similar to those in atminE1 and arc6 guard cells. Nevertheless, unlike atminE1 and arc6, parc6 exhibited a low number of mini-chloroplasts (< 2 µm diameter) and rarely produced chloroplast-deficient guard cells. Importantly, unlike parc6, the chloroplast division site mutant arc11 exhibited WT-like plastid phenotypes in trichome and guard cells. Finally, observation of parc6 complementation lines expressing a functional PARC6-GFP protein indicated that PARC6-GFP formed a ring-like structure in both constricting and non-constricting chloroplasts, and that PARC6 dynamically changes its configuration during the process of chloroplast division.
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Affiliation(s)
- Hiroki Ishikawa
- Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, Tokyo, Japan
| | - Mana Yasuzawa
- Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, Tokyo, Japan
| | - Nana Koike
- Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, Tokyo, Japan
| | - Alvin Sanjaya
- Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, Tokyo, Japan
| | - Shota Moriyama
- Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, Tokyo, Japan
| | - Aya Nishizawa
- Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, Tokyo, Japan
| | - Kanae Matsuoka
- Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, Tokyo, Japan
| | - Shun Sasaki
- Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, Tokyo, Japan
| | - Yusuke Kazama
- Nishina Center for Accelerator-Based Science, RIKEN, Wako, Japan
| | - Yoriko Hayashi
- Nishina Center for Accelerator-Based Science, RIKEN, Wako, Japan
| | - Tomoko Abe
- Nishina Center for Accelerator-Based Science, RIKEN, Wako, Japan
| | - Makoto T. Fujiwara
- Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, Tokyo, Japan
- Nishina Center for Accelerator-Based Science, RIKEN, Wako, Japan
| | - Ryuuichi D. Itoh
- Department of Chemistry, Biology and Marine Science, Faculty of Science, University of the Ryukyus, Okinawa, Japan
- *Correspondence: Ryuuichi D. Itoh,
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16
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Zhuang X, Jiang L. Chloroplast Degradation: Multiple Routes Into the Vacuole. FRONTIERS IN PLANT SCIENCE 2019; 10:359. [PMID: 30972092 PMCID: PMC6443708 DOI: 10.3389/fpls.2019.00359] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Accepted: 03/07/2019] [Indexed: 05/05/2023]
Abstract
Chloroplasts provide energy for all plants by producing sugar during photosynthesis. To adapt to various environmental and developmental cues, plants have developed specific strategies to control chloroplast homeostasis in plant cells, including chloroplast degradation during leaf senescence and the transition of chloroplasts into other types of plastids during the day-night cycle. In recent years, autophagy has emerged as an essential mechanism for selective degradation of chloroplast materials (also known as chlorophagy) in the vacuole. Different types of membrane structures have been implicated to involve in the delivery of distinct chloroplast contents. Here we provide a current overview on chlorophagy and discuss the possible chloroplast receptors and upstream signals in this process.
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Affiliation(s)
- Xiaohong Zhuang
- School of Life Sciences, Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Hong Kong, China
- The Chinese University of Hong Kong Shenzhen Research Institute, Shenzhen, China
- *Correspondence: Xiaohong Zhuang,
| | - Liwen Jiang
- School of Life Sciences, Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Hong Kong, China
- The Chinese University of Hong Kong Shenzhen Research Institute, Shenzhen, China
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17
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LaBrant E, Barnes AC, Roston RL. Lipid transport required to make lipids of photosynthetic membranes. PHOTOSYNTHESIS RESEARCH 2018; 138:345-360. [PMID: 29961189 DOI: 10.1007/s11120-018-0545-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 06/20/2018] [Indexed: 05/21/2023]
Abstract
Photosynthetic membranes provide much of the usable energy for life on earth. To produce photosynthetic membrane lipids, multiple transport steps are required, including fatty acid export from the chloroplast stroma to the endoplasmic reticulum, and lipid transport from the endoplasmic reticulum to the chloroplast envelope membranes. Transport of hydrophobic molecules through aqueous space is energetically unfavorable and must be catalyzed by dedicated enzymes, frequently on specialized membrane structures. Here, we review photosynthetic membrane lipid transport to the chloroplast in the context of photosynthetic membrane lipid synthesis. We independently consider the identity of transported lipids, the proteinaceous transport components, and membrane structures which may allow efficient transport. Recent advances in lipid transport of chloroplasts, bacteria, and other systems strongly suggest that lipid transport is achieved by multiple mechanisms which include membrane contact sites with specialized protein machinery. This machinery is likely to include the TGD1, 2, 3 complex with the TGD5 and TGD4/LPTD1 systems, and may also include a number of proteins with domains similar to other membrane contact site lipid-binding proteins. Importantly, the likelihood of membrane contact sites does not preclude lipid transport by other mechanisms including vectorial acylation and vesicle transport. Substantial progress is needed to fully understand all photosynthetic membrane lipid transport processes and how they are integrated.
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Affiliation(s)
- Evan LaBrant
- Department of Biochemistry, University of Nebraska-Lincoln, 1901 Vine St, Lincoln, NE, 68588, USA
| | - Allison C Barnes
- Department of Biochemistry, University of Nebraska-Lincoln, 1901 Vine St, Lincoln, NE, 68588, USA
| | - Rebecca L Roston
- Department of Biochemistry, University of Nebraska-Lincoln, 1901 Vine St, Lincoln, NE, 68588, USA.
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18
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Erickson JL, Schattat MH. Shaping plastid stromules-principles of in vitro membrane tubulation applied in planta. CURRENT OPINION IN PLANT BIOLOGY 2018; 46:48-54. [PMID: 30041102 DOI: 10.1016/j.pbi.2018.07.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 07/01/2018] [Accepted: 07/06/2018] [Indexed: 05/10/2023]
Abstract
Plastids undergo drastic shape changes under stress, including the formation of stroma-filled tubules, or `stromules'. Stromules are dynamic, and may extend, branch and retract within minutes. There are two prerequisites for stromule extension: excess plastid membrane and a force(s) that shapes the membrane into a tubule. In vitro studies provide insight into the basic molecular machinery for tubulation, and are often cited when discussing stromule formation. In this review, we evaluate in vitro modes of tubulation in the context of stromule dynamics, and find that most mechanisms fail to explain stromule morphology and behavior observed in planta. Current data support a model of stromule formation relying on pulling motors (myosins and kinesins) and cytoskeleton (actin and microtubules).
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Affiliation(s)
- Jessica Lee Erickson
- Department of Plant Physiology, Institute for Biology, Martin Luther University Halle-Wittenberg, D-06099 Halle, Germany
| | - Martin Hartmut Schattat
- Department of Plant Physiology, Institute for Biology, Martin Luther University Halle-Wittenberg, D-06099 Halle, Germany.
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19
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Itoh RD, Ishikawa H, Nakajima KP, Moriyama S, Fujiwara MT. Isolation and analysis of a stromule-overproducing Arabidopsis mutant suggest the role of PARC6 in plastid morphology maintenance in the leaf epidermis. PHYSIOLOGIA PLANTARUM 2018; 162:479-494. [PMID: 28984364 DOI: 10.1111/ppl.12648] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 09/24/2017] [Accepted: 10/02/2017] [Indexed: 05/10/2023]
Abstract
Stromules, or stroma-filled tubules, are thin extensions of the plastid envelope membrane that are most frequently observed in undifferentiated or non-mesophyll cells. The formation of stromules is developmentally regulated and responsive to biotic and abiotic stress; however, the physiological roles and molecular mechanisms of the stromule formation remain enigmatic. Accordingly, we attempted to obtain Arabidopsis thaliana mutants with aberrant stromule biogenesis in the leaf epidermis. Here, we characterize one of the obtained mutants. Plastids in the leaf epidermis of this mutant were giant and pleomorphic, typically having one or more constrictions that indicated arrested plastid division, and usually possessed one or more extremely long stromules, which indicated the deregulation of stromule formation. Genetic mapping, whole-genome resequencing-aided exome analysis, and gene complementation identified PARC6/CDP1/ARC6H, which encodes a vascular plant-specific, chloroplast division site-positioning factor, as the causal gene for the stromule phenotype. Yeast two-hybrid assay and double mutant analysis also identified a possible interaction between PARC6 and MinD1, another known chloroplast division site-positioning factor, during the morphogenesis of leaf epidermal plastids. To the best of our knowledge, PARC6 is the only known A. thaliana chloroplast division factor whose mutations more extensively affect the morphology of plastids in non-mesophyll tissue than in mesophyll tissue. Therefore, the present study demonstrates that PARC6 plays a pivotal role in the morphology maintenance and stromule regulation of non-mesophyll plastids.
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Affiliation(s)
- Ryuuichi D Itoh
- Department of Chemistry, Biology and Marine Science, Faculty of Science, University of the Ryukyus, Okinawa, Japan
| | - Hiroki Ishikawa
- Department of Biology, Graduate School of Science and Technology, Sophia University, Tokyo, Japan
| | - Kohdai P Nakajima
- Department of Chemistry, Biology and Marine Science, Faculty of Science, University of the Ryukyus, Okinawa, Japan
| | - Shota Moriyama
- Department of Biology, Graduate School of Science and Technology, Sophia University, Tokyo, Japan
| | - Makoto T Fujiwara
- Department of Biology, Graduate School of Science and Technology, Sophia University, Tokyo, Japan
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20
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Fujiwara MT, Yasuzawa M, Kojo KH, Niwa Y, Abe T, Yoshida S, Nakano T, Itoh RD. The Arabidopsis arc5 and arc6 mutations differentially affect plastid morphology in pavement and guard cells in the leaf epidermis. PLoS One 2018; 13:e0192380. [PMID: 29466386 PMCID: PMC5821325 DOI: 10.1371/journal.pone.0192380] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 01/20/2018] [Indexed: 01/09/2023] Open
Abstract
Chloroplasts, or photosynthetic plastids, multiply by binary fission, forming a homogeneous population in plant cells. In Arabidopsis thaliana, the division apparatus (or division ring) of mesophyll chloroplasts includes an inner envelope transmembrane protein ARC6, a cytoplasmic dynamin-related protein ARC5 (DRP5B), and members of the FtsZ1 and FtsZ2 families of proteins, which co-assemble in the stromal mid-plastid division ring (FtsZ ring). FtsZ ring placement is controlled by several proteins, including a stromal factor MinE (AtMinE1). During leaf mesophyll development, ARC6 and AtMinE1 are necessary for FtsZ ring formation and thus plastid division initiation, while ARC5 is essential for a later stage of plastid division. Here, we examined plastid morphology in leaf epidermal pavement cells (PCs) and stomatal guard cells (GCs) in the arc5 and arc6 mutants using stroma-targeted fluorescent proteins. The arc5 PC plastids were generally a bit larger than those of the wild type, but most had normal shapes and were division-competent, unlike mutant mesophyll chloroplasts. The arc6 PC plastids were heterogeneous in size and shape, including the formation of giant and mini-plastids, plastids with highly developed stromules, and grape-like plastid clusters, which varied on a cell-by-cell basis. Moreover, unique plastid phenotypes for stomatal GCs were observed in both mutants. The arc5 GCs rarely lacked chlorophyll-bearing plastids (chloroplasts), while they accumulated minute chlorophyll-less plastids, whereas most GCs developed wild type-like chloroplasts. The arc6 GCs produced large chloroplasts and/or chlorophyll-less plastids, as previously observed, but unexpectedly, their chloroplasts/plastids exhibited marked morphological variations. We quantitatively analyzed plastid morphology and partitioning in paired GCs from wild-type, arc5, arc6, and atminE1 plants. Collectively, our results support the notion that ARC5 is dispensable in the process of equal division of epidermal plastids, and indicate that dysfunctions in ARC5 and ARC6 differentially affect plastid replication among mesophyll cells, PCs, and GCs within a single leaf.
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Affiliation(s)
- Makoto T. Fujiwara
- Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, Chiyoda, Tokyo, Japan
- Nishina Center and Plant Functions Laboratory, RIKEN, Wako, Saitama, Japan
| | - Mana Yasuzawa
- Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, Chiyoda, Tokyo, Japan
| | - Kei H. Kojo
- Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, Chiyoda, Tokyo, Japan
| | - Yasuo Niwa
- Laboratory of Plant Molecular Improvement, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, Suruga, Shizuoka, Japan
| | - Tomoko Abe
- Nishina Center and Plant Functions Laboratory, RIKEN, Wako, Saitama, Japan
| | - Shigeo Yoshida
- Nishina Center and Plant Functions Laboratory, RIKEN, Wako, Saitama, Japan
| | - Takeshi Nakano
- Gene Discovery Research Group, Center for Sustainable Resource Science, RIKEN, Wako, Saitama, Japan
- CREST, JST (Japan Science and Technology Agency), Kawaguchi, Saitama, Japan
| | - Ryuuichi D. Itoh
- Department of Chemistry, Biology and Marine Science, Faculty of Science, University of the Ryukyus, Nishihara, Okinawa, Japan
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21
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Delfosse K, Wozny MR, Barton KA, Mathur N, Griffiths N, Mathur J. Plastid Envelope-Localized Proteins Exhibit a Stochastic Spatiotemporal Relationship to Stromules. FRONTIERS IN PLANT SCIENCE 2018; 9:754. [PMID: 29915611 PMCID: PMC5995270 DOI: 10.3389/fpls.2018.00754] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 05/16/2018] [Indexed: 05/13/2023]
Abstract
UNLABELLED Plastids in the viridiplantae sporadically form thin tubules called stromules that increase the interactive surface between the plastid and the surrounding cytoplasm. Several recent publications that report observations of certain proteins localizing to the extensions have then used the observations to suggest stromule-specific functions. The mechanisms by which specific localizations on these transient and sporadically formed extensions might occur remain unclear. Previous studies have yet to address the spatiotemporal relationship between a particular protein localization pattern and its distribution on an extended stromules and/or the plastid body. Here, we have used discrete protein patches found in several transgenic plants as fiducial markers to investigate this relationship. While we consider the inner plastid envelope-membrane localized protein patches of the GLUCOSE 6-PHOSPHATE/PHOSPHATE TRANSLOCATOR1 and the TRIOSE-PHOSPHATE/ PHOSPHATE TRANSLOCATOR 1 as artifacts of fluorescent fusion protein over-expression, stromule formation is not compromised in the respective stable transgenic lines that maintain normal growth and development. Our analysis of chloroplasts in the transgenic lines in the Arabidopsis Columbia background, and in the arc6 mutant, under stromule-inducing conditions shows that the possibility of finding a particular protein-enriched domain on an extended stromule or on a region of the main plastid body is stochastic. Our observations provide insights on the behavior of chloroplasts, the relationship between stromules and the plastid-body and strongly challenge claims of stromule-specific functions based solely upon protein localization to plastid extensions. ONE SENTENCE SUMMARY Observations of the spatiotemporal relationship between plastid envelope localized fluorescent protein fusions of two sugar-phosphate transporters and stromules suggest a stochastic rather than specific localization pattern that questions the idea of independent functions for stromules.
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22
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Vincent AE, Turnbull DM, Eisner V, Hajnóczky G, Picard M. Mitochondrial Nanotunnels. Trends Cell Biol 2017; 27:787-799. [PMID: 28935166 PMCID: PMC5749270 DOI: 10.1016/j.tcb.2017.08.009] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 08/11/2017] [Accepted: 08/22/2017] [Indexed: 01/13/2023]
Abstract
Insight into the regulation of complex physiological systems emerges from understanding how biological units communicate with each other. Recent findings show that mitochondria communicate at a distance with each other via nanotunnels, thin double-membrane protrusions that connect the matrices of non-adjacent mitochondria. Emerging evidence suggest that mitochondrial nanotunnels are generated by immobilized mitochondria and transport proteins. This review integrates data from the evolutionarily conserved structure and function of intercellular projections in bacteria with recent developments in mitochondrial imaging that permit nanotunnel visualization in eukaryotes. Cell type-specificity, timescales, and the selective size-based diffusion of biomolecules along nanotunnels are also discussed. The joining of individual mitochondria into dynamic networks of communicating organelles via nanotunnels and other mechanisms has major implications for organelle and cellular behaviors.
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Affiliation(s)
- Amy E Vincent
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neurosciences, Newcastle University, Newcastle upon Tyne, UK
| | - Doug M Turnbull
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neurosciences, Newcastle University, Newcastle upon Tyne, UK
| | - Veronica Eisner
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - György Hajnóczky
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Martin Picard
- Division of Behavioral Medicine, Department of Psychiatry, Columbia University Medical Center, New York, NY, USA; Department of Neurology, The Merritt Center and Columbia Translational Neuroscience Initiative, Columbia University Medical Center, New York, NY, USA; Columbia Aging Center, Columbia University Mailman School of Public Health, New York, NY 10032, USA.
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23
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Fujiwara MT, Yasuzawa M, Sasaki S, Nakano T, Niwa Y, Yoshida S, Abe T, Itoh RD. The Arabidopsis minD mutation causes aberrant FtsZ1 ring placement and moderate heterogeneity of chloroplasts in the leaf epidermis. PLANT SIGNALING & BEHAVIOR 2017. [PMID: 28644708 PMCID: PMC5586359 DOI: 10.1080/15592324.2017.1343776] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Symmetric division of leaf mesophyll chloroplasts requires MinD and MinE, which work together to suppress division other than at the mid-chloroplast. arc11 is a MinD loss-of-function mutant of Arabidopsis thaliana. In arc11 plants, asymmetric chloroplast division, as well as its delay or arrest, results in extreme size polymorphism of chloroplasts in mature mesophyll cells. The current study examined chloroplast phenotypes in the epidermis of arc11 leaves. Fluorescence microscopy analysis revealed that epidermal chloroplasts in mature leaves exhibited moderate heterogeneity in size. This probably resulted from completion of many of the previous non-equatorial or multiple division events in expanding leaves. Additionally, analyses of plastids found that epidermal chloroplasts in arc11 mutants showed several phenotypes that have not previously been described.
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Affiliation(s)
- Makoto T. Fujiwara
- Nishina Center and Plant Functions Laboratory, RIKEN, Wako, Saitama, Japan
- Department of Biology, Sophia University, Chiyoda, Tokyo, Japan
- CONTACT Makoto T. Fujiwara Department of Biology, Sophia University, 7–1 Kioicho, Chiyoda, Tokyo, 102-8554, Japan
| | - Mana Yasuzawa
- Department of Biology, Sophia University, Chiyoda, Tokyo, Japan
| | - Shun Sasaki
- Department of Biology, Sophia University, Chiyoda, Tokyo, Japan
| | - Takeshi Nakano
- Gene Discovery Research Group, RIKEN Center for Sustainable Resource Science, Wako, Saitama, Japan
- CREST, JST (Japan Science and Technology Agency), Kawaguchi, Saitama, Japan
| | - Yasuo Niwa
- Laboratory of Plant Molecular Improvement, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, Suruga, Shizuoka, Japan
| | - Shigeo Yoshida
- Nishina Center and Plant Functions Laboratory, RIKEN, Wako, Saitama, Japan
| | - Tomoko Abe
- Nishina Center and Plant Functions Laboratory, RIKEN, Wako, Saitama, Japan
| | - Ryuuichi D. Itoh
- Department of Chemistry, Biology and Marine Science, Faculty of Science, University of the Ryukyus, Nishihara, Okinawa, Japan
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Betti M, Bauwe H, Busch FA, Fernie AR, Keech O, Levey M, Ort DR, Parry MAJ, Sage R, Timm S, Walker B, Weber APM. Manipulating photorespiration to increase plant productivity: recent advances and perspectives for crop improvement. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:2977-88. [PMID: 26951371 DOI: 10.1093/jxb/erw076] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Recycling of the 2-phosphoglycolate generated by the oxygenase reaction of Rubisco requires a complex and energy-consuming set of reactions collectively known as the photorespiratory cycle. Several approaches aimed at reducing the rates of photorespiratory energy or carbon loss have been proposed, based either on screening for natural variation or by means of genetic engineering. Recent work indicates that plant yield can be substantially improved by the alteration of photorespiratory fluxes or by engineering artificial bypasses to photorespiration. However, there is also evidence indicating that, under certain environmental and/or nutritional conditions, reduced photorespiratory capacity may be detrimental to plant performance. Here we summarize recent advances obtained in photorespiratory engineering and discuss prospects for these advances to be transferred to major crops to help address the globally increasing demand for food and biomass production.
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Affiliation(s)
- Marco Betti
- Departamento de Bioquímica Vegetal y Biología Molecular, Facultad de Química, 41012 Sevilla, Spain
| | - Hermann Bauwe
- Plant Physiology Department, University of Rostock, D-18051 Rostock, Germany
| | - Florian A Busch
- Research School of Biology, The Australian National University, Canberra ACT 2601, Australia
| | - Alisdair R Fernie
- Max-Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Olivier Keech
- Department of Plant Physiology, Umeå Plant Science Centre, Umeå University, S-90187 Umeå, Sweden
| | - Myles Levey
- Institute of Plant Molecular and Developmental Biology, Heinrich-Heine-University, 40225 Düsseldorf, Germany
| | - Donald R Ort
- Global Change and Photosynthesis Research Unit, United States Department of Agriculture/Agricultural Research Service, Urbana, IL 61801, USA Institute for Genomic Biology, University of Illinois, Urbana, IL 61801, USA
| | - Martin A J Parry
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK
| | - Rowan Sage
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada, M5S 3B2
| | - Stefan Timm
- Plant Physiology Department, University of Rostock, D-18051 Rostock, Germany
| | - Berkley Walker
- Global Change and Photosynthesis Research Unit, United States Department of Agriculture/Agricultural Research Service, Urbana, IL 61801, USA Carl Woese Institute for Genomic Biology, University of Illinois, Urbana, IL 61801, USA
| | - Andreas P M Weber
- Institute of Plant Biochemistry, Cluster of Excellence on Plant Science (CEPLAS), Heinrich-Heine-University, 40225 Düsseldorf, Germany
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Celler K, Fujita M, Kawamura E, Ambrose C, Herburger K, Holzinger A, Wasteneys GO. Microtubules in Plant Cells: Strategies and Methods for Immunofluorescence, Transmission Electron Microscopy, and Live Cell Imaging. Methods Mol Biol 2016; 1365:155-84. [PMID: 26498784 DOI: 10.1007/978-1-4939-3124-8_8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Microtubules (MTs) are required throughout plant development for a wide variety of processes, and different strategies have evolved to visualize and analyze them. This chapter provides specific methods that can be used to analyze microtubule organization and dynamic properties in plant systems and summarizes the advantages and limitations for each technique. We outline basic methods for preparing samples for immunofluorescence labeling, including an enzyme-based permeabilization method, and a freeze-shattering method, which generates microfractures in the cell wall to provide antibodies access to cells in cuticle-laden aerial organs such as leaves. We discuss current options for live cell imaging of MTs with fluorescently tagged proteins (FPs), and provide chemical fixation, high-pressure freezing/freeze substitution, and post-fixation staining protocols for preserving MTs for transmission electron microscopy and tomography.
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Affiliation(s)
- Katherine Celler
- Department of Botany, The University of British Columbia, Vancouver, BC, Canada
| | - Miki Fujita
- Department of Botany, The University of British Columbia, Vancouver, BC, Canada
| | - Eiko Kawamura
- Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - Chris Ambrose
- Department of Biology, University of Saskatchewan, Saskatoon, SK, Canada
| | - Klaus Herburger
- Functional Plant Biology, Institute of Botany, University of Innsbruck, Sternwartestraße 15, 6020, Innsbruck, Austria
| | - Andreas Holzinger
- Functional Plant Biology, Institute of Botany, University of Innsbruck, Sternwartestraße 15, 6020, Innsbruck, Austria.
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Fujiwara MT, Kojo KH, Kazama Y, Sasaki S, Abe T, Itoh RD. The Arabidopsis minE mutation causes new plastid and FtsZ1 localization phenotypes in the leaf epidermis. FRONTIERS IN PLANT SCIENCE 2015; 6:823. [PMID: 26500667 PMCID: PMC4593956 DOI: 10.3389/fpls.2015.00823] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 09/22/2015] [Indexed: 05/25/2023]
Abstract
Plastids in the leaf epidermal cells of plants are regarded as immature chloroplasts that, like mesophyll chloroplasts, undergo binary fission. While mesophyll chloroplasts have generally been used to study plastid division, recent studies have suggested the presence of tissue- or plastid type-dependent regulation of plastid division. Here, we report the detailed morphology of plastids and their stromules, and the intraplastidic localization of the chloroplast division-related protein AtFtsZ1-1, in the leaf epidermis of an Arabidopsis mutant that harbors a mutation in the chloroplast division site determinant gene AtMinE1. In atminE1, the size and shape of epidermal plastids varied widely, which contrasts with the plastid phenotype observed in atminE1 mesophyll cells. In particular, atminE1 epidermal plastids occasionally displayed grape-like morphology, a novel phenotype induced by a plastid division mutation. Observation of an atminE1 transgenic line harboring an AtMinE1 promoter::AtMinE1-yellow fluorescent protein fusion gene confirmed the expression and plastidic localization of AtMinE1 in the leaf epidermis. Further examination revealed that constriction of plastids and stromules mediated by the FtsZ1 ring contributed to the plastid pleomorphism in the atminE1 epidermis. These results illustrate that a single plastid division mutation can have dramatic consequences for epidermal plastid morphology, thereby implying that plastid division and morphogenesis are differentially regulated in epidermal and mesophyll plastids.
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Affiliation(s)
- Makoto T. Fujiwara
- RIKEN Nishina CenterSaitama, Japan
- Graduate School of Science and Technology, Sophia UniversityTokyo, Japan
| | - Kei H. Kojo
- Graduate School of Science and Technology, Sophia UniversityTokyo, Japan
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of TokyoKashiwa, Japan
- LPixel Inc.Tokyo, Japan
| | | | - Shun Sasaki
- Graduate School of Science and Technology, Sophia UniversityTokyo, Japan
| | | | - Ryuuichi D. Itoh
- Department of Chemistry, Biology and Marine Science, Faculty of Science, University of the RyukyusOkinawa, Japan
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Brunkard JO, Runkel AM, Zambryski PC. Chloroplasts extend stromules independently and in response to internal redox signals. Proc Natl Acad Sci U S A 2015; 112:10044-9. [PMID: 26150490 PMCID: PMC4538653 DOI: 10.1073/pnas.1511570112] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
A fundamental mystery of plant cell biology is the occurrence of "stromules," stroma-filled tubular extensions from plastids (such as chloroplasts) that are universally observed in plants but whose functions are, in effect, completely unknown. One prevalent hypothesis is that stromules exchange signals or metabolites between plastids and other subcellular compartments, and that stromules are induced during stress. Until now, no signaling mechanisms originating within the plastid have been identified that regulate stromule activity, a critical missing link in this hypothesis. Using confocal and superresolution 3D microscopy, we have shown that stromules form in response to light-sensitive redox signals within the chloroplast. Stromule frequency increased during the day or after treatment with chemicals that produce reactive oxygen species specifically in the chloroplast. Silencing expression of the chloroplast NADPH-dependent thioredoxin reductase, a central hub in chloroplast redox signaling pathways, increased chloroplast stromule frequency, whereas silencing expression of nuclear genes related to plastid genome expression and tetrapyrrole biosynthesis had no impact on stromules. Leucoplasts, which are not photosynthetic, also made more stromules in the daytime. Leucoplasts did not respond to the same redox signaling pathway but instead increased stromule formation when exposed to sucrose, a major product of photosynthesis, although sucrose has no impact on chloroplast stromule frequency. Thus, different types of plastids make stromules in response to distinct signals. Finally, isolated chloroplasts could make stromules independently after extraction from the cytoplasm, suggesting that chloroplast-associated factors are sufficient to generate stromules. These discoveries demonstrate that chloroplasts are remarkably autonomous organelles that alter their stromule frequency in reaction to internal signal transduction pathways.
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Affiliation(s)
- Jacob O Brunkard
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720
| | - Anne M Runkel
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720
| | - Patricia C Zambryski
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720
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Delfosse K, Wozny MR, Jaipargas EA, Barton KA, Anderson C, Mathur J. Fluorescent Protein Aided Insights on Plastids and their Extensions: A Critical Appraisal. FRONTIERS IN PLANT SCIENCE 2015; 6:1253. [PMID: 26834765 PMCID: PMC4719081 DOI: 10.3389/fpls.2015.01253] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2015] [Accepted: 12/21/2015] [Indexed: 05/20/2023]
Abstract
Multi-colored fluorescent proteins targeted to plastids have provided new insights on the dynamic behavior of these organelles and their interactions with other cytoplasmic components and compartments. Sub-plastidic components such as thylakoids, stroma, the inner and outer membranes of the plastid envelope, nucleoids, plastoglobuli, and starch grains have been efficiently highlighted in living plant cells. In addition, stroma filled membrane extensions called stromules have drawn attention to the dynamic nature of the plastid and its interactions with the rest of the cell. Use of dual and triple fluorescent protein combinations has begun to reveal plastid interactions with mitochondria, the nucleus, the endoplasmic reticulum and F-actin and suggests integral roles of plastids in retrograde signaling, cell to cell communication as well as plant-pathogen interactions. While the rapid advances and insights achieved through fluorescent protein based research on plastids are commendable it is necessary to endorse meaningful observations but subject others to closer scrutiny. Here, in order to develop a better and more comprehensive understanding of plastids and their extensions we provide a critical appraisal of recent information that has been acquired using targeted fluorescent protein probes.
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Schattat MH, Barton KA, Mathur J. The myth of interconnected plastids and related phenomena. PROTOPLASMA 2015; 252:359-71. [PMID: 24965372 DOI: 10.1007/s00709-014-0666-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 06/12/2014] [Indexed: 05/08/2023]
Abstract
Studies spread over nearly two and a half centuries have identified the primary plastid in autotrophic algae and plants as a pleomorphic, multifunctional organelle comprising of a double-membrane envelope enclosing an organization of internal membranes submerged in a watery stroma. All plastid units have been observed extending and retracting thin stroma-filled tubules named stromules sporadically. Observations on living plant cells often convey the impression that stromules connect two or more independent plastids with each other. When photo-bleaching techniques were used to suggest that macromolecules such as the green fluorescent protein could flow between already interconnected plastids, for many people this impression changed to conviction. However, it was noticed only recently that the concept of protein flow between plastids rests solely on the words "interconnected plastids" for which details have never been provided. We have critically reviewed botanical literature dating back to the 1880s for understanding this term and the phenomena that have become associated with it. We find that while meticulously detailed ontogenic studies spanning nearly 150 years have established the plastid as a singular unit organelle, there is no experimental support for the idea that interconnected plastids exist under normal conditions of growth and development. In this review, while we consider several possibilities that might allow a single elongated plastid to be misinterpreted as two or more interconnected plastids, our final conclusion is that the concept of direct protein flow between plastids is based on an unfounded assumption.
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Affiliation(s)
- Martin H Schattat
- Martin-Luther-Universität Halle-Wittenberg Pflanzenphysiologie, Weinbergweg 10, 06120, Halle (Saale), Germany,
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Wilson ME, Basu MR, Bhaskara GB, Verslues PE, Haswell ES. Plastid osmotic stress activates cellular stress responses in Arabidopsis. PLANT PHYSIOLOGY 2014; 165:119-28. [PMID: 24676856 PMCID: PMC4012573 DOI: 10.1104/pp.114.236620] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 03/25/2014] [Indexed: 05/21/2023]
Abstract
Little is known about cytoplasmic osmoregulatory mechanisms in plants, and even less is understood about how the osmotic properties of the cytoplasm and organelles are coordinately regulated. We have previously shown that Arabidopsis (Arabidopsis thaliana) plants lacking functional versions of the plastid-localized mechanosensitive ion channels Mechanosensitive Channel of Small Conductance-Like2 (MSL2) and MSL3 contain leaf epidermal plastids under hypoosmotic stress, even during normal growth and development. Here, we use the msl2 msl3 mutant as a model to investigate the cellular response to constitutive plastid osmotic stress. Under unstressed conditions, msl2 msl3 seedlings exhibited several hallmarks of drought or environmental osmotic stress, including solute accumulation, elevated levels of the compatible osmolyte proline (Pro), and accumulation of the stress hormone abscisic acid (ABA). Furthermore, msl2 msl3 mutants expressed Pro and ABA metabolism genes in a pattern normally seen under drought or osmotic stress. Pro accumulation in the msl2 msl3 mutant was suppressed by conditions that reduce plastid osmotic stress or inhibition of ABA biosynthesis. Finally, treatment of unstressed msl2 msl3 plants with exogenous ABA elicited a much greater Pro accumulation response than in the wild type, similar to that observed in plants under drought or osmotic stress. These results suggest that osmotic imbalance across the plastid envelope can elicit a response similar to that elicited by osmotic imbalance across the plasma membrane and provide evidence for the integration of the osmotic state of an organelle into that of the cell in which it resides.
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Abstract
Plastid division is fundamental to the biology of plant cells. Division by binary fission entails the coordinated assembly and constriction of four concentric rings, two internal and two external to the organelle. The internal FtsZ ring and external dynamin-like ARC5/DRP5B ring are connected across the two envelopes by the membrane proteins ARC6, PARC6, PDV1, and PDV2. Assembly-stimulated GTPase activity drives constriction of the FtsZ and ARC5/DRP5B rings, which together with the plastid-dividing rings pull and squeeze the envelope membranes until the two daughter plastids are formed, with the final separation requiring additional proteins. The positioning of the division machinery is controlled by the chloroplast Min system, which confines FtsZ-ring formation to the plastid midpoint. The dynamic morphology of plastids, especially nongreen plastids, is also considered here, particularly in relation to the production of stromules and plastid-derived vesicles and their possible roles in cellular communication and plastid functionality.
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Wang P, Zhang J, Su J, Wang P, Liu J, Liu B, Feng D, Wang J, Wang H. The chloroplast min system functions differentially in two specific nongreen plastids in Arabidopsis thaliana. PLoS One 2013; 8:e71190. [PMID: 23936263 PMCID: PMC3728212 DOI: 10.1371/journal.pone.0071190] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 06/26/2013] [Indexed: 01/12/2023] Open
Abstract
The nongreen plastids, such as etioplasts, chromoplasts, etc., as well as chloroplasts, are all derived from proplastids in the meristem. To date, the Min system members in plants have been identified as regulators of FtsZ-ring placement, which are essential for the symmetrical division of chloroplasts. However, the regulation of FtsZ-ring placement in nongreen plastids is poorly understood. In this study, we investigated the division site placement of nongreen plastids by examining the etioplasts as representative in Arabidopsis Min system mutants. Surprisingly, the shape and number of etioplasts in cotyledons of arc3, arc11 and mcd1 mutants were similar to that observed in wild-type plants, whereas arc12 and parc6 mutants exhibited enlarged etioplasts that were reduced in number. In order to examine nongreen plastids in true leaves, we silenced the ALB3 gene in these Min system mutant backgrounds to produce immature chloroplasts without the thylakoidal network using virus induced gene silencing (VIGS). Interestingly, consistent with our observations in etioplasts, enlarged and fewer nongreen plastids were only detected in leaves of parc6 (VIGS-ALB3) and arc12 (VIGS-ALB3) plants. Further, the FtsZ-ring assembled properly at the midpoint in nongreen plastids of arc3, arc11 and mcd1 (VIGS-ALB3) plants, but organized into multiple rings in parc6 (VIGS-ALB3) and presented fragmented filaments in arc12 (VIGS-ALB3) plants, suggesting that division site placement in nongreen plastids requires fewer components of the plant Min system. Taken together, these results suggest that division site placement in nongreen plastids is different from that in chloroplasts.
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Affiliation(s)
- Peng Wang
- Guangdong Key Laboratory of Plant Resources and State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, People’s Republic of China
| | - Jie Zhang
- Guangdong Key Laboratory of Plant Resources and State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, People’s Republic of China
| | - Jianbin Su
- Guangdong Key Laboratory of Plant Resources and State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, People’s Republic of China
| | - Peng Wang
- Guangdong Key Laboratory of Plant Resources and State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, People’s Republic of China
| | - Jun Liu
- Guangdong Key Laboratory of Plant Resources and State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, People’s Republic of China
| | - Bing Liu
- Guangdong Key Laboratory of Plant Resources and State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, People’s Republic of China
| | - Dongru Feng
- Guangdong Key Laboratory of Plant Resources and State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, People’s Republic of China
| | - Jinfa Wang
- Guangdong Key Laboratory of Plant Resources and State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, People’s Republic of China
| | - Hongbin Wang
- Guangdong Key Laboratory of Plant Resources and State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, People’s Republic of China
- * E-mail:
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Velikanov GA, Levanov VY, Belova LP, Ponomareva AA, Il’ina TM. Adjustable channel for diffusion between vacuoles of next cells: Vacuolar symplast. ACTA ACUST UNITED AC 2012. [DOI: 10.1134/s2079086412040093] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Schattat M, Barton K, Baudisch B, Klösgen RB, Mathur J. Plastid stromule branching coincides with contiguous endoplasmic reticulum dynamics. PLANT PHYSIOLOGY 2011; 155:1667-77. [PMID: 21273446 PMCID: PMC3091094 DOI: 10.1104/pp.110.170480] [Citation(s) in RCA: 111] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2010] [Accepted: 01/24/2011] [Indexed: 05/18/2023]
Abstract
Stromules are stroma-filled tubules extending from plastids whose rapid extension toward or retraction from other plastids has suggested a role in interplastidic communication and exchange of metabolites. Several studies point to sporadic dilations, kinks, and branches occurring along stromule length but have not elucidated the underlying basis for these occurrences. Similarly, although specific details on interacting partners have been missing, a consensus viewpoint suggests that stromules increase the interactive surface of a plastid with its cytoplasmic surroundings. Here, using live imaging, we show that the behavior of dynamic, pleomorphic stromules strongly coincides with that of cortical endoplasmic reticulum (ER) tubules. Covisualization of fluorescent protein-highlighted stromules and the ER in diverse cell types clearly suggests correlative dynamics of the two membrane-bound compartments. The extension and retraction, as well as directional changes in stromule branches occur in tandem with the behavior of neighboring ER tubules. Three-dimensional and four-dimensional volume rendering reveals that stromules that extend into cortical regions occupy channels between ER tubules possibly through multiple membrane contact sites. Our observations clearly depict coincidental stromule-ER behavior and suggest that either the neighboring ER tubules shape stromules directly or the behavior of both ER and stromules is simultaneously dictated by a shared cytoskeleton-based mechanism. These new observations strongly implicate the ER membrane in interactions with stromules and suggest that their interacting surfaces might serve as major conduits for bidirectional exchange of ions, lipids, and metabolites between the two organelles.
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Affiliation(s)
| | | | | | | | - Jaideep Mathur
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G2W1 (M.S., K.B., J.M.); Institut für Biologie-Pflanzenphysiologie, Martin-Luther-Universität Halle-Wittenberg, 06120 Halle/Saale, Germany (B.B., R.B.K.)
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Hanson MR, Sattarzadeh A. Stromules: recent insights into a long neglected feature of plastid morphology and function. PLANT PHYSIOLOGY 2011; 155:1486-92. [PMID: 21330493 PMCID: PMC3091082 DOI: 10.1104/pp.110.170852] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2011] [Accepted: 02/16/2011] [Indexed: 05/20/2023]
Affiliation(s)
- Maureen R Hanson
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853, USA.
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37
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Breuers FKH, Bräutigam A, Weber APM. The Plastid Outer Envelope - A Highly Dynamic Interface between Plastid and Cytoplasm. FRONTIERS IN PLANT SCIENCE 2011; 2:97. [PMID: 22629266 PMCID: PMC3355566 DOI: 10.3389/fpls.2011.00097] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Accepted: 11/29/2011] [Indexed: 05/09/2023]
Abstract
Plastids are the defining organelles of all photosynthetic eukaryotes. They are the site of photosynthesis and of a large number of other essential metabolic pathways, such as fatty acid and amino acid biosyntheses, sulfur and nitrogen assimilation, and aromatic and terpenoid compound production, to mention only a few examples. The metabolism of plastids is heavily intertwined and connected with that of the surrounding cytosol, thus causing massive traffic of metabolic precursors, intermediates, and products. Two layers of biological membranes that are called the inner (IE) and the outer (OE) plastid envelope membranes bound the plastids of Archaeplastida. While the IE is generally accepted as the osmo-regulatory barrier between cytosol and stroma, the OE was considered to represent an unspecific molecular sieve, permeable for molecules of up to 10 kDa. However, after the discovery of small substrate specific pores in the OE, this view has come under scrutiny. In addition to controlling metabolic fluxes between plastid and cytosol, the OE is also crucial for protein import into the chloroplast. It contains the receptors and translocation channel of the TOC complex that is required for the canonical post-translational import of nuclear-encoded, plastid-targeted proteins. Further, the OE is a metabolically active compartment of the chloroplast, being involved in, e.g., fatty acid metabolism and membrane lipid production. Also, recent findings hint on the OE as a defense platform against several biotic and abiotic stress conditions, such as cold acclimation, freezing tolerance, and phosphate deprivation. Moreover, dynamic non-covalent interactions between the OE and the endomembrane system are thought to play important roles in lipid and non-canonical protein trafficking between plastid and endoplasmic reticulum. While proteomics and bioinformatics has provided us with comprehensive but still incomplete information on proteins localized in the plastid IE, the stroma, and the thylakoids, our knowledge of the protein composition of the plastid OE is far from complete. In this article, we report on the recent progress in discovering novel OE proteins to draw a conclusive picture of the OE. A "parts list" of the plastid OE will be presented, using data generated by proteomics of plastids isolated from various plant sources.
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Affiliation(s)
| | - Andrea Bräutigam
- Institut für Biochemie der Pflanzen, Heinrich-Heine Universität DüsseldorfDüsseldorf, Germany
| | - Andreas P. M. Weber
- Institut für Biochemie der Pflanzen, Heinrich-Heine Universität DüsseldorfDüsseldorf, Germany
- *Correspondence: Andreas P. M. Weber, Institut für Biochemie der Pflanzen, Heinrich-Heine Universität Düsseldorf, Universitätstrasse 1, D-40225 Düsseldorf, Germany. e-mail:
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Abstract
Stromules are thin stroma-filled tubules that extend from all plastid types in all multicellular plants examined. They are most easily visualised by epifluorescence or confocal microscopy of plastids containing green fluorescent protein (GFP) or other fluorescent proteins. Transient expression of gene constructs encoding plastid-targeted GFP following bombardment of whole plants or organs of Arabidopsis with gold or tungsten particles coated with plasmid DNA is a relatively rapid and simple means of producing material for observation of stromules.
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Affiliation(s)
- John C Gray
- Department of Plant Sciences, University of Cambridge, Cambridge, UK.
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Miyagishima SY, Kabeya Y. Chloroplast division: squeezing the photosynthetic captive. Curr Opin Microbiol 2010; 13:738-46. [PMID: 21041111 DOI: 10.1016/j.mib.2010.10.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2010] [Revised: 09/28/2010] [Accepted: 10/06/2010] [Indexed: 10/18/2022]
Abstract
Chloroplasts have evolved from a cyanobacterial endosymbiont and have been retained in eukaryotic cells for more than one billion years via chloroplast division and inheritance by daughter cells during cell division. Recent studies revealed that chloroplast division is performed by a large protein complex at the division site, encompassing both the inside and the outside of the two envelope membranes. The division complex has retained a few components of the cyanobacterial division complex to go along with other components supplied by the host cell. On the basis of the information about the division complex, we are beginning to understand how the division complex evolved, and how eukaryotic host cells regulate chloroplast division during proliferation and differentiation.
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Affiliation(s)
- Shin-Ya Miyagishima
- Initiative Research Program, Advanced Science Institute, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
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Pyke KA. Plastid division. AOB PLANTS 2010; 2010:plq016. [PMID: 22476074 PMCID: PMC2995336 DOI: 10.1093/aobpla/plq016] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Revised: 08/19/2010] [Accepted: 09/28/2010] [Indexed: 05/25/2023]
Abstract
BACKGROUND AND AIMS Plastids undergo a process of binary fission in order to replicate. Plastid replication is required at two distinct stages of plant growth: during cell division to ensure correct plastid segregation, and during cell expansion and development to generate large populations of functional plastids, as in leaf mesophyll cells. This review considers some of the recent advances in the understanding of how plastids undergo binary fission, a process which uses several different proteins, both internal and external to the plastid, which have been derived from the original endosymbiont's genome as well as new proteins that have been recruited from the host genome. KEY POINTS Several of the proteins currently used in this process in higher plants have homologues in modern-day bacteria. An alternative mode of replication by a budding-type mechanism also appears to be used in some circumstances. The review also highlights how most of our knowledge of plastid division is centred on the chloroplast developing in leaf mesophyll cells and a role for plastid division during the development of other plastid types is poorly understood. Whilst models for a protein-based mechanism have been devised, exactly how the division process is controlled at the plastid level and at the plastid population level is poorly understood.
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Affiliation(s)
- Kevin Andrew Pyke
- Plant and Crop Sciences Division , School of Biosciences, University of Nottingham , Sutton Bonington Campus, Loughborough LE12 5RD , UK
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Zellnig G, Perktold A, Zechmann B. Fine structural quantification of drought-stressed Picea abies (L.) organelles based on 3D reconstructions. PROTOPLASMA 2010; 243:129-36. [PMID: 19544038 DOI: 10.1007/s00709-009-0058-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2009] [Accepted: 06/05/2009] [Indexed: 05/08/2023]
Abstract
Ultrastructural investigations of cells and organelles by transmission electron microscopy (TEM) usually lead to two-dimensional information of cell structures without supplying exact quantitative data due to the limited number of investigated ultrathin sections. This can lead to misinterpretation of observed structures especially in context of their three-dimensional (3D) assembly. 3D investigations and quantitative morphometric analysis are therefore essential to get detailed information about the arrangement and the amount of subcellular structures inside a cell or organelle, respectively, especially when the plant sample was exposed to environmental stress. In the present research, serial sectioned chloroplasts, mitochondria, and peroxisomes from first year spruce needles (Picea abies (L.) Karst.) were 3D reconstructed and digitally measured using a computer-supported image analysis system in order to obtain a detailed quantitative characterization of complete cell organelles including precise morphological data of drought-induced fine structural changes. In control plants, chloroplast volume was composed of 56% stroma, 15% starch, 27% thylakoids, and 2% plastoglobules. In drought-stressed chloroplasts, the relative volume of both the thylakoids and the plastoglobules significantly increased to 37% and 12%, respectively. Chloroplasts of stressed plants differed from control plants not only in the mean thylakoid and plastoglobules content but also in the complete lack of starch grains. Mitochondria occurred in variable forms in both control and stressed samples. In stressed plants, mitochondria showed a significant smaller mean volume which was only 81% when compared with the control organelles. Peroxisomes were inconspicuous in both samples and their volume did not differ between control and drought-stressed samples. The present study shows that specific subcellular structures are subject to significant quantitative changes during drought stress of spruce needles giving a detailed insight in adaptation processes of the investigated cell organelles.
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Affiliation(s)
- Günther Zellnig
- Institute of Plant Sciences, University of Graz, Schubertstrasse 51, 8010 Graz, Austria.
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Itoh R, Fujiwara MT. Regulation of leucoplast morphology in roots: interorganellar signaling from mitochondria? PLANT SIGNALING & BEHAVIOR 2010; 5:856-9. [PMID: 20505352 PMCID: PMC3014538 DOI: 10.4161/psb.5.7.11893] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2010] [Accepted: 03/23/2010] [Indexed: 05/22/2023]
Abstract
The appearance of leaf mesophyll chloroplasts in angiosperms is characterized by their uniform and static shape, which is molded by symmetric division of the preexisting organelles, involving three prokaryote-derived proteins: the division executor protein, FtsZ, and the division site positioning proteins, MinD and MinE. On the other hand, noncolored plastids in roots, where the involvement of the known chloroplast division factors in plastid morphogenesis is yet unclear, are morphologically heterogeneous and transform dynamically. This is further emphasized by the active formation of long tubular protrusions called stromules from the main body of those plastids. Molecular regulation and physiological significance of such dynamic morphology of root plastids also remain unknown. In this context, we have recently demonstrated that the mitochondrial respiratory inhibitor antimycin A induces rapid and reversible filamentation of root plastids (leucoplasts) in Arabidopsis thaliana. In contrast, the same treatment with antimycin A did not affect the morphology of amyloplasts in the columella cells at the root tip. The alternative oxidase inhibitor salicylhydroxamic acid suppresses the antimycin-induced plastid filamentation, perhaps implying an alternative oxidase-mediated interorganellar signaling between the mitochondria and the leucoplasts in the root cells. Our data may provide some clues as to how the formation of stromules is initiated.
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Affiliation(s)
- Ryuuichi Itoh
- Department of Chemistry, Biology and Marine Science, Faculty of Science, University of the Ryukyus, Nishihara, Okinawa, Japan.
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Itoh RD, Yamasaki H, Septiana A, Yoshida S, Fujiwara MT. Chemical induction of rapid and reversible plastid filamentation in Arabidopsis thaliana roots. PHYSIOLOGIA PLANTARUM 2010; 139:144-58. [PMID: 20088905 DOI: 10.1111/j.1399-3054.2010.01352.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Plastids assume various morphologies depending on their developmental status, but the basis for developmentally regulated plastid morphogenesis is poorly understood. Chemical induction of alterations in plastid morphology would be a useful tool for studying this; however, no such chemicals have been identified. Here, we show that antimycin A, an effective respiratory inhibitor, can change plastid morphology rapidly and reversibly in Arabidopsis thaliana. In the root cortex, hypocotyls, cotyledon epidermis and true leaf epidermis, significant differences in mitochondrial morphology were not observed between antimycin-treated and untreated tissues. In contrast, antimycin caused extreme filamentation of plastids in the mature cortices of main roots. This phenomenon was specifically observed in the mature root cortex. Other mitochondrial respiratory inhibitors (rotenone and carbonyl cyanide m-chlorophenylhydrazone), hydrogen peroxide, S-nitroso-N-acetylpenicillamine [a nitric oxide (NO) donor] and 3-(3,4-dichlorophenyl)-1,1-dimethylurea did not mimic the phenomenon under the present study conditions. Antimycin-induced plastid filamentation was initiated within 5 min after the onset of chemical treatment and appeared to complete within 1 h. Plastid morphology was restored within 7 h after the washout of antimycin, suggesting that the filamentation was reversible. Co-applications of antimycin and cytoskeletal inhibitors (demecolcine or latrunculin B) or protein synthesis inhibitors (cycloheximide or chloramphenicol) still caused plastid filamentation. Antimycin A was also effective for plastid filamentation in the chloroplast division mutants atftsZ1-1 and atminE1. Salicylhydroxamic acid, an alternative oxidase inhibitor, was solely found to suppress the filamentation, implying the possibility that this phenomenon was partly mediated by an antimycin-activated alternative oxidase in the mitochondria.
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Affiliation(s)
- Ryuuichi D Itoh
- Department of Chemistry, Biology and Marine Science, Faculty of Science, University of the Ryukyus, Senbaru 1, Nishihara, Okinawa 903-0213, Japan.
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Fujiwara MT, Hashimoto H, Kazama Y, Hirano T, Yoshioka Y, Aoki S, Sato N, Itoh RD, Abe T. Dynamic morphologies of pollen plastids visualised by vegetative-specific FtsZ1-GFP in Arabidopsis thaliana. PROTOPLASMA 2010; 242:19-33. [PMID: 20195657 DOI: 10.1007/s00709-010-0119-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2009] [Accepted: 02/05/2010] [Indexed: 05/22/2023]
Abstract
The behaviour and multiplication of pollen plastids have remained elusive despite their crucial involvement in cytoplasmic inheritance. Here, we present live images of plastids in pollen grains and growing tubes from transgenic Arabidopsis thaliana lines expressing stroma-localised FtsZ1-green-fluorescent protein fusion in a vegetative cell-specific manner. Vegetative cells in mature pollen contained a morphologically heterogeneous population of round to ellipsoidal plastids, whilst those in late-developing (maturing) pollen included plastids that could have one or two constriction sites. Furthermore, plastids in pollen tubes exhibited remarkable tubulation, stromule (stroma-filled tubule) extension, and back-and-forth movement along the direction of tube growth. Plastid division, which involves the FtsZ1 ring, was rarely observed in mature pollen grains.
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Abstract
Microtubules are required throughout plant development for a wide variety of processes, and different strategies have been evolved to visualize them. This chapter summarizes the most effective of these methods and points out potential problems and pitfalls. We outline the freeze-shattering method for immunolabeling microtubules in aerial organs such as leaves that require mechanical permeabilization, discuss current options for live cell imaging of MTs with fluorescently tagged proteins (FPs), and provide different fixation protocols for preserving MTs for transmission electron microscopy including chemical fixation, high pressure freezing/freeze substitution, and post-fixation staining procedures for transmission electron microscopy.
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Affiliation(s)
- Andreas Holzinger
- Institute of Botany, Department of Physiology and Cell Physiology, University of Innsbruck, Innsbruck, Austria
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Schmitz AJ, Glynn JM, Olson BJSC, Stokes KD, Osteryoung KW. Arabidopsis FtsZ2-1 and FtsZ2-2 are functionally redundant, but FtsZ-based plastid division is not essential for chloroplast partitioning or plant growth and development. MOLECULAR PLANT 2009; 2:1211-22. [PMID: 19995726 DOI: 10.1093/mp/ssp077] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
FtsZ1 and FtsZ2 are phylogenetically distinct families of FtsZ in plants that co-localize to mid-plastid rings and facilitate division of chloroplasts. In plants, altered levels of either FtsZ1 or FtsZ2 cause dose-dependent defects in chloroplast division; thus, studies on the functional relationship between FtsZ genes require careful manipulation of FtsZ levels in vivo. To define the functional relationship between the two FtsZ2 genes in Arabidopsis thaliana, FtsZ2-1 and FtsZ2-2, we expressed FtsZ2-1 in an ftsZ2-2 null mutant, and vice versa, and determined whether the chloroplast division defects were rescued in plants expressing different total levels of FtsZ2. Full rescue was observed when either the FtsZ2-1 or FtsZ2-2 level approximated total FtsZ2 levels in wild-type (WT). Additionally, FtsZ2-2 interacts with ARC6, as shown previously for FtsZ2-1. These data indicate that FtsZ2-1 and FtsZ2-2 are functionally redundant for chloroplast division in Arabidopsis. To rigorously validate the requirement of each FtsZ family for chloroplast division, we replaced FtsZ1 with FtsZ2 in vivo, and vice versa, while maintaining the FtsZ level in the transgenic plants equal to that of the total level in WT. Chloroplast division defects were not rescued, demonstrating conclusively that FtsZ1 and FtsZ2 are non-redundant for maintenance of WT chloroplast numbers. Finally, we generated ftsZ triple null mutants and show that plants completely devoid of FtsZ protein are viable and fertile. As plastids are presumably essential organelles, these findings suggest that an FtsZ-independent mode of plastid partitioning may occur in higher plants.
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Affiliation(s)
- Aaron J Schmitz
- Department of Plant Biology, 166 Plant Biology Bldg, Michigan State University, East Lansing, MI 48824-1312, USA
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Guirimand G, Burlat V, Oudin A, Lanoue A, St-Pierre B, Courdavault V. Optimization of the transient transformation of Catharanthus roseus cells by particle bombardment and its application to the subcellular localization of hydroxymethylbutenyl 4-diphosphate synthase and geraniol 10-hydroxylase. PLANT CELL REPORTS 2009; 28:1215-34. [PMID: 19504099 DOI: 10.1007/s00299-009-0722-2] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2009] [Revised: 04/30/2009] [Accepted: 05/14/2009] [Indexed: 05/07/2023]
Abstract
The monoterpene indole alkaloids (MIA) synthesized in Catharanthus roseus are highly valuable metabolites due to their pharmacological properties. In planta, the MIA biosynthetic pathway exhibits a complex compartmentation at the cellular level, whereas subcellular data are sparse. To gain insight into this level of organization, we have developed a high efficiency green fluorescent protein (GFP) imaging approach to systematically localize MIA biosynthetic enzymes within C. roseus cells following a biolistic-mediated transient transformation. The biolistic transformation protocol has been first optimized to obtain a high number of transiently transformed cells with a ~12-fold increase compared to previous protocols and thus to clearly and easily identify the fusion GFP expression patterns in numerous cells. On the basis of this protocol, the subcellular localization of hydroxymethylbutenyl 4-diphosphate synthase (HDS), a methyl erythritol phosphate pathway enzyme and geraniol 10-hydroxylase (G10H), a monoterpene-secoiridoid pathway enzyme has been next characterized. Besides showing the accumulation of HDS within plastids of C. roseus cells, we also provide evidences of the presence of HDS in long stroma-filled thylakoid-free extensions budding from plastids, i.e. stromules that are in close association with other organelles such as endoplasmic reticulum (ER) or mitochondria in agreement with their proposed function in enhancing interorganelle metabolite exchanges. Furthermore, we also demonstrated that G10H is an ER-anchored protein, consistent with the presence of a transmembrane helix at the G10H N-terminal end, which is both necessary and sufficient to drive the ER anchoring.
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Affiliation(s)
- Grégory Guirimand
- Université François Rabelais de Tours, EA 2106 Biomolécules et Biotechnologies Végétales, IFR 135 Imagerie fonctionnelle, 37200, Tours, France
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Briggs WR, Lin C. Introduction to the Symposium-in-Print on photosynthesis. Photochem Photobiol 2008; 84:1300-1. [PMID: 19067953 DOI: 10.1111/j.1751-1097.2008.00463.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Winslow R Briggs
- Carnegie Institution for Science, Plant Biology, Stanford, CA, USA.
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Yang Y, Glynn JM, Olson BJSC, Schmitz AJ, Osteryoung KW. Plastid division: across time and space. CURRENT OPINION IN PLANT BIOLOGY 2008; 11:577-84. [PMID: 18990608 DOI: 10.1016/j.pbi.2008.10.001] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2008] [Revised: 09/27/2008] [Accepted: 10/03/2008] [Indexed: 05/24/2023]
Abstract
Plastid division is executed by the coordinated action of at least two molecular machineries--an internal machinery situated on the stromal side of the inner envelope membrane that was contributed by the cyanobacterial endosymbiont from which plastids evolved, and an external machinery situated on the cytosolic side of the outer envelope membrane that was contributed by the host. Here we review progress in defining the components of the plastid division complex and understanding the mechanisms of envelope constriction and division-site placement in plants. We also highlight recent work identifying the first molecular linkage between the internal and external division machineries, shedding light on how their mid-plastid positioning is coordinated across the envelope membranes. Little is known about the mechanisms that regulate plastid division in plant cells, but recent studies have begun to hint at potential mechanisms.
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Affiliation(s)
- Yue Yang
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824, USA
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