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Lu Z, Zhang J, Wang H, Zhang K, Gu Z, Xu Y, Zhang J, Wang M, Han L, Xiang F, Zhou C. Rewiring of a KNOXI regulatory network mediated by UFO underlies the compound leaf development in Medicago truncatula. Nat Commun 2024; 15:2988. [PMID: 38582884 PMCID: PMC10998843 DOI: 10.1038/s41467-024-47362-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Accepted: 03/28/2024] [Indexed: 04/08/2024] Open
Abstract
Class I KNOTTED-like homeobox (KNOXI) genes are parts of the regulatory network that control the evolutionary diversification of leaf morphology. Their specific spatiotemporal expression patterns in developing leaves correlate with the degrees of leaf complexity between simple-leafed and compound-leafed species. However, KNOXI genes are not involved in compound leaf formation in several legume species. Here, we identify a pathway for dual repression of MtKNOXI function in Medicago truncatula. PINNATE-LIKE PENTAFOLIATA1 (PINNA1) represses the expression of MtKNOXI, while PINNA1 interacts with MtKNOXI and sequesters it to the cytoplasm. Further investigations reveal that UNUSUAL FLORAL ORGANS (MtUFO) is the direct target of MtKNOXI, and mediates the transition from trifoliate to pinnate-like pentafoliate leaves. These data suggest a new layer of regulation for morphological diversity in compound-leafed species, in which the conserved regulators of floral development, MtUFO, and leaf development, MtKNOXI, are involved in variation of pinnate-like compound leaves in M. truncatula.
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Affiliation(s)
- Zhichao Lu
- The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, 266237, China
| | - Juanjuan Zhang
- The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, 266237, China
| | - Hongfeng Wang
- The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, 266237, China
- Shandong Peanut Research Institute, Qingdao, 266199, China
| | - Ke Zhang
- The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, 266237, China
| | - Zhiqun Gu
- The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, 266237, China
| | - Yiteng Xu
- The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, 266237, China
| | - Jing Zhang
- The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, 266237, China
| | - Min Wang
- The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, 266237, China
| | - Lu Han
- The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, 266237, China
| | - Fengning Xiang
- The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, 266237, China
| | - Chuanen Zhou
- The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, 266237, China.
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2
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Schreiber JM, Limpens E, de Keijzer J. Distributing Plant Developmental Regulatory Proteins via Plasmodesmata. PLANTS (BASEL, SWITZERLAND) 2024; 13:684. [PMID: 38475529 DOI: 10.3390/plants13050684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 02/21/2024] [Accepted: 02/22/2024] [Indexed: 03/14/2024]
Abstract
During plant development, mobile proteins, including transcription factors, abundantly serve as messengers between cells to activate transcriptional signaling cascades in distal tissues. These proteins travel from cell to cell via nanoscopic tunnels in the cell wall known as plasmodesmata. Cellular control over this intercellular movement can occur at two likely interdependent levels. It involves regulation at the level of plasmodesmata density and structure as well as at the level of the cargo proteins that traverse these tunnels. In this review, we cover the dynamics of plasmodesmata formation and structure in a developmental context together with recent insights into the mechanisms that may control these aspects. Furthermore, we explore the processes involved in cargo-specific mechanisms that control the transport of proteins via plasmodesmata. Instead of a one-fits-all mechanism, a pluriform repertoire of mechanisms is encountered that controls the intercellular transport of proteins via plasmodesmata to control plant development.
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Affiliation(s)
- Joyce M Schreiber
- Laboratory of Cell and Developmental Biology, Wageningen University and Research, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Erik Limpens
- Laboratory of Molecular Biology, Wageningen University and Research, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Jeroen de Keijzer
- Laboratory of Cell and Developmental Biology, Wageningen University and Research, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
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3
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Kitagawa M, Tran TM, Jackson D. Traveling with purpose: cell-to-cell transport of plant mRNAs. Trends Cell Biol 2024; 34:48-57. [PMID: 37380581 DOI: 10.1016/j.tcb.2023.05.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 05/19/2023] [Accepted: 05/29/2023] [Indexed: 06/30/2023]
Abstract
Messenger RNAs (mRNAs) in multicellular organisms can act as signals transported cell-to-cell and over long distances. In plants, mRNAs traffic cell-to-cell via plasmodesmata (PDs) and over long distances via the phloem vascular system to control diverse biological processes - such as cell fate and tissue patterning - in destination organs. Research on long-distance transport of mRNAs in plants has made remarkable progress, including the cataloguing of many mobile mRNAs, characterization of mRNA features important for transport, identification of mRNA-binding proteins involved in their transport, and understanding of the physiological roles of mRNA transport. However, information on short-range mRNA cell-to-cell transport is still limited. This review discusses the regulatory mechanisms and physiological functions of mRNA transport at the cellular and whole plant levels.
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Affiliation(s)
- Munenori Kitagawa
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan 430070, PR China
| | - Thu M Tran
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - David Jackson
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA.
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4
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Hong L, Fletcher JC. Stem Cells: Engines of Plant Growth and Development. Int J Mol Sci 2023; 24:14889. [PMID: 37834339 PMCID: PMC10573764 DOI: 10.3390/ijms241914889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2023] [Revised: 09/30/2023] [Accepted: 10/03/2023] [Indexed: 10/15/2023] Open
Abstract
The development of both animals and plants relies on populations of pluripotent stem cells that provide the cellular raw materials for organ and tissue formation. Plant stem cell reservoirs are housed at the shoot and root tips in structures called meristems, with the shoot apical meristem (SAM) continuously producing aerial leaf, stem, and flower organs throughout the life cycle. Thus, the SAM acts as the engine of plant development and has unique structural and molecular features that allow it to balance self-renewal with differentiation and act as a constant source of new cells for organogenesis while simultaneously maintaining a stem cell reservoir for future organ formation. Studies have identified key roles for intercellular regulatory networks that establish and maintain meristem activity, including the KNOX transcription factor pathway and the CLV-WUS stem cell feedback loop. In addition, the plant hormones cytokinin and auxin act through their downstream signaling pathways in the SAM to integrate stem cell activity and organ initiation. This review discusses how the various regulatory pathways collectively orchestrate SAM function and touches on how their manipulation can alter stem cell activity to improve crop yield.
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Affiliation(s)
- Liu Hong
- Plant Gene Expression Center, United States Department of Agriculture—Agricultural Research Service, Albany, CA 94710, USA;
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, CA 94720, USA
| | - Jennifer C. Fletcher
- Plant Gene Expression Center, United States Department of Agriculture—Agricultural Research Service, Albany, CA 94710, USA;
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, CA 94720, USA
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5
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Kirschner GK. Local call or long-distance call: studying cell-to-cell transport by Arabidopsis callus grafting. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2023; 115:299-300. [PMID: 37449309 DOI: 10.1111/tpj.16358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/18/2023]
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6
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Yang L, Zhou Y, Wang S, Xu Y, Ostendorp S, Tomkins M, Kehr J, Morris RJ, Kragler F. Noncell-autonomous HSC70.1 chaperone displays homeostatic feedback regulation by binding its own mRNA. THE NEW PHYTOLOGIST 2023; 237:2404-2421. [PMID: 36564968 DOI: 10.1111/nph.18703] [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: 11/04/2022] [Accepted: 12/08/2022] [Indexed: 06/17/2023]
Abstract
The HSC70/HSP70 family of heat shock proteins are evolutionarily conserved chaperones involved in protein folding, protein transport, and RNA binding. Arabidopsis HSC70 chaperones are thought to act as housekeeping chaperones and as such are involved in many growth-related pathways. Whether Arabidopsis HSC70 binds RNA and whether this interaction is functional has remained an open question. We provide evidence that the HSC70.1 chaperone binds its own mRNA via its C-terminal short variable region (SVR) and inhibits its own translation. The SVR encoding mRNA region is necessary for HSC70.1 transcript mobility to distant tissues and that HSC70.1 transcript and not protein mobility is required to rescue root growth and flowering time of hsc70 mutants. We propose that this negative protein-transcript feedback loop may establish an on-demand chaperone pool that allows for a rapid response to stress. In summary, our data suggest that the Arabidopsis HSC70.1 chaperone can form a complex with its own transcript to regulate its translation and that both protein and transcript can act in a noncell-autonomous manner, potentially maintaining chaperone homeostasis between tissues.
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Affiliation(s)
- Lei Yang
- Max-Planck-Institute of Molecular Plant Physiology, Wissenschaftspark Golm, Am Mühlenberg 1, 14476, Golm, Germany
| | - Yuan Zhou
- Max-Planck-Institute of Molecular Plant Physiology, Wissenschaftspark Golm, Am Mühlenberg 1, 14476, Golm, Germany
| | - Shuangfeng Wang
- Max-Planck-Institute of Molecular Plant Physiology, Wissenschaftspark Golm, Am Mühlenberg 1, 14476, Golm, Germany
| | - Ying Xu
- Max-Planck-Institute of Molecular Plant Physiology, Wissenschaftspark Golm, Am Mühlenberg 1, 14476, Golm, Germany
| | - Steffen Ostendorp
- Institute for Plant Science and Microbiology, Universität Hamburg, Ohnhorststr. 18, 22609, Hamburg, Germany
| | - Melissa Tomkins
- Computational and Systems Biology, John Innes Centre, Norwich, NR4 7UH, UK
| | - Julia Kehr
- Institute for Plant Science and Microbiology, Universität Hamburg, Ohnhorststr. 18, 22609, Hamburg, Germany
| | - Richard J Morris
- Computational and Systems Biology, John Innes Centre, Norwich, NR4 7UH, UK
| | - Friedrich Kragler
- Max-Planck-Institute of Molecular Plant Physiology, Wissenschaftspark Golm, Am Mühlenberg 1, 14476, Golm, Germany
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7
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Ostendorp A, Ostendorp S, Zhou Y, Chaudron Z, Wolffram L, Rombi K, von Pein L, Falke S, Jeffries CM, Svergun DI, Betzel C, Morris RJ, Kragler F, Kehr J. Intrinsically disordered plant protein PARCL colocalizes with RNA in phase-separated condensates whose formation can be regulated by mutating the PLD. J Biol Chem 2022; 298:102631. [PMID: 36273579 PMCID: PMC9679465 DOI: 10.1016/j.jbc.2022.102631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 10/16/2022] [Accepted: 10/17/2022] [Indexed: 11/21/2022] Open
Abstract
In higher plants, long-distance RNA transport via the phloem is crucial for communication between distant plant tissues to align development with stress responses and reproduction. Several recent studies suggest that specific RNAs are among the potential long-distance information transmitters. However, it is yet not well understood how these RNAs enter the phloem stream, how they are transported, and how they are released at their destination. It was proposed that phloem RNA-binding proteins facilitate RNA translocation. In the present study, we characterized two orthologs of the phloem-associated RNA chaperone-like (PARCL) protein from Arabidopsis thaliana and Brassica napus at functional and structural levels. Microscale thermophoresis showed that these phloem-abundant proteins can bind a broad spectrum of RNAs and show RNA chaperone activity in FRET-based in vitro assays. Our SAXS experiments revealed a high degree of disorder, typical for RNA-binding proteins. In agroinfiltrated tobacco plants, eYFP-PARCL proteins mainly accumulated in nuclei and nucleoli and formed cytosolic and nuclear condensates. We found that formation of these condensates was impaired by tyrosine-to-glutamate mutations in the predicted prion-like domain (PLD), while C-terminal serine-to-glutamate mutations did not affect condensation but reduced RNA binding and chaperone activity. Furthermore, our in vitro experiments confirmed phase separation of PARCL and colocalization of RNA with the condensates, while mutation as well as phosphorylation of the PLD reduced phase separation. Together, our results suggest that RNA binding and condensate formation of PARCL can be regulated independently by modification of the C-terminus and/or the PLD.
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Affiliation(s)
- Anna Ostendorp
- Universität Hamburg, Department of Biology, Institute of Plant Science and Microbiology, Hamburg, Germany,For correspondence: Anna Ostendorp
| | - Steffen Ostendorp
- Universität Hamburg, Department of Biology, Institute of Plant Science and Microbiology, Hamburg, Germany
| | - Yuan Zhou
- Max Planck Institute of Molecular Plant Physiology, Department II, Potsdam, Germany
| | - Zoé Chaudron
- Universität Hamburg, Department of Biology, Institute of Plant Science and Microbiology, Hamburg, Germany
| | - Lukas Wolffram
- Universität Hamburg, Department of Biology, Institute of Plant Science and Microbiology, Hamburg, Germany
| | - Khadija Rombi
- Universität Hamburg, Department of Biology, Institute of Plant Science and Microbiology, Hamburg, Germany
| | - Linn von Pein
- Universität Hamburg, Department of Biology, Institute of Plant Science and Microbiology, Hamburg, Germany
| | - Sven Falke
- Laboratory for Structural Biology of Infection and Inflammation, c/o DESY, Hamburg, Germany,Universität Hamburg, Department of Chemistry, Institute of Biochemistry and Molecular Biology, Hamburg, Germany
| | - Cy M. Jeffries
- European Molecular Biology Laboratory (EMBL) Hamburg Site, c/o DESY, Hamburg, Germany
| | - Dmitri I. Svergun
- European Molecular Biology Laboratory (EMBL) Hamburg Site, c/o DESY, Hamburg, Germany
| | - Christian Betzel
- Laboratory for Structural Biology of Infection and Inflammation, c/o DESY, Hamburg, Germany,Universität Hamburg, Department of Chemistry, Institute of Biochemistry and Molecular Biology, Hamburg, Germany
| | - Richard J. Morris
- Computational and Systems Biology, John Innes Centre, Norwich, United Kingdom
| | - Friedrich Kragler
- Max Planck Institute of Molecular Plant Physiology, Department II, Potsdam, Germany
| | - Julia Kehr
- Universität Hamburg, Department of Biology, Institute of Plant Science and Microbiology, Hamburg, Germany
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8
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Li R, Wei Z, Li Y, Shang X, Cao Y, Duan L, Ma L. SKI-INTERACTING PROTEIN interacts with SHOOT MERISTEMLESS to regulate shoot apical meristem formation. PLANT PHYSIOLOGY 2022; 189:2193-2209. [PMID: 35640153 PMCID: PMC9342996 DOI: 10.1093/plphys/kiac241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 05/02/2022] [Indexed: 06/15/2023]
Abstract
The shoot apical meristem (SAM), which is formed during embryogenesis, generates leaves, stems, and floral organs during the plant life cycle. SAM development is controlled by SHOOT MERISTEMLESS (STM), a conserved Class I KNOX transcription factor that interacts with another subclass homeodomain protein, BELL, to form a heterodimer, which regulates gene expression at the transcriptional level in Arabidopsis (Arabidopsis thaliana). Meanwhile, SKI-INTERACTING PROTEIN (SKIP), a conserved protein in eukaryotes, works as both a splicing factor and as a transcriptional regulator in plants to control gene expression at the transcriptional and posttranscriptional levels by interacting with distinct partners. Here, we show that, similar to plants with a loss of function of STM, a loss of function of SKIP or the specific knockout of SKIP in the SAM region resulted in failed SAM development and the inability of the mutants to complete their life cycle. In comparison, Arabidopsis mutants that expressed SKIP specifically in the SAM region formed a normal SAM and were able to generate a shoot system, including leaves and floral organs. Further analysis confirmed that SKIP interacts with STM in planta and that SKIP and STM regulate the expression of a similar set of genes by binding to their promoters. In addition, STM also interacts with EARLY FLOWERING 7 (ELF7), a component of Polymerase-Associated Factor 1 complex, and mutation in ELF7 exhibits similar SAM defects to that of STM and SKIP. This work identifies a component of the STM transcriptional complex and reveals the mechanism underlying SKIP-mediated SAM formation in Arabidopsis.
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Affiliation(s)
- Ruiqi Li
- State Key Laboratory of Plant Physiology and Biochemistry, College of Agriculture and Biotechnology, China Agricultural University, Beijing 100193, China
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Zhifeng Wei
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Yan Li
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Xudong Shang
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Ying Cao
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Liusheng Duan
- State Key Laboratory of Plant Physiology and Biochemistry, College of Agriculture and Biotechnology, China Agricultural University, Beijing 100193, China
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9
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Tan FQ, Wang W, Li J, Lu Y, Zhu B, Hu F, Li Q, Zhao Y, Zhou DX. A coiled-coil protein associates Polycomb Repressive Complex 2 with KNOX/BELL transcription factors to maintain silencing of cell differentiation-promoting genes in the shoot apex. THE PLANT CELL 2022; 34:2969-2988. [PMID: 35512211 PMCID: PMC9338815 DOI: 10.1093/plcell/koac133] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 04/25/2022] [Indexed: 05/06/2023]
Abstract
Polycomb repressive complex 2 (PRC2), which mediates the deposition of H3K27me3 histone marks, is important for developmental decisions in animals and plants. In the shoot apical meristem (SAM), Three Amino acid Loop Extension family KNOTTED-LIKE HOMEOBOX /BEL-like (KNOX/BELL) transcription factors are key regulators of meristem cell pluripotency and differentiation. Here, we identified a PRC2-associated coiled-coil protein (PACP) that interacts with KNOX/BELL transcription factors in rice (Oryza sativa) shoot apex cells. A loss-of-function mutation of PACP resulted in differential gene expression similar to that observed in PRC2 gene knockdown plants, reduced H3K27me3 levels, and reduced genome-wide binding of the PRC2 core component EMF2b. The genomic binding of PACP displayed a similar distribution pattern to EMF2b, and genomic regions with high PACP- and EMF2b-binding signals were marked by high levels of H3K27me3. We show that PACP is required for the repression of cell differentiation-promoting genes targeted by a rice KNOX1 protein in the SAM. PACP is involved in the recruitment or stabilization of PRC2 to genes targeted by KNOX/BELL transcription factors to maintain H3K27me3 and gene repression in dividing cells of the shoot apex. Our results provide insight into PRC2-mediated maintenance of H3K27me3 and the mechanism by which KNOX/BELL proteins regulate SAM development.
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Affiliation(s)
| | | | - Junjie Li
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China
| | - Yue Lu
- Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding/Key Laboratory of Plant Functional Genomics of the Ministry of Education, College of Agriculture, Yangzhou University, Yangzhou 225009, China
| | - Bo Zhu
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China
| | - Fangfang Hu
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China
| | - Qi Li
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China
| | - Yu Zhao
- Authors for correspondence: (Y.Z.); (D.X.Z.)
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10
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Kitagawa M, Xu X, Jackson D. Trafficking and localization of KNOTTED1 related mRNAs in shoot meristems. Commun Integr Biol 2022; 15:158-163. [PMID: 35832536 PMCID: PMC9272838 DOI: 10.1080/19420889.2022.2095125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Multicellular organisms use transcripts and proteins as signaling molecules for cell-to-cell communication. Maize KNOTTED1 (KN1) was the first homeodomain transcription factor identified in plants, and functions in maintaining shoot stem cells. KN1 acts non-cell autonomously, and both its messenger RNA (mRNA) and protein traffic between cells through intercellular nanochannels called plasmodesmata. KN1 protein and mRNA trafficking are regulated by a chaperonin subunit and a catalytic subunit of the RNA exosome, respectively. These studies suggest that the function of KN1 in stem cell regulation requires the cell-to-cell transport of both its protein and mRNA. However, in situ hybridization experiments published 25 years ago suggested that KN1 mRNA was missing from the epidermal (L1) layer of shoot meristems, suggesting that only the KN1 protein could traffic. Here, we show evidence that KN1 mRNA is present at a low level in L1 cells of maize meristems, supporting an idea that both KN1 protein and mRNA traffic to the L1 layer. We also summarize mRNA expression patterns of KN1 homologs in diverse angiosperm species, and discuss KN1 trafficking mechanisms.
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Affiliation(s)
| | - Xiaosa Xu
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA
| | - David Jackson
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA
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11
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A Forward Genetic Approach to Identify Plasmodesmal Trafficking Regulators Based on Trichome Rescue. METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2022; 2457:393-407. [PMID: 35349156 DOI: 10.1007/978-1-0716-2132-5_27] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Plasmodesmata (PD) are channels in the walls of plant cells which enable cell-to-cell information transfer. This includes the selective transport of specific transcription factors that control cell fate during plant development. KNOTTED1 (KN1) homeobox (KNOX) family transcription factors that are essential for the maintenance and function of stem cells in shoot meristems use this trafficking pathway, but its mechanism is largely unknown. Here we describe a forward genetic approach to the identification of regulators of selective KN1 trafficking through PD, using a trichome rescue system that permits simple visual analysis in Arabidopsis leaves. A KN1 trafficking regulator identified in this approach had the capacity to regulate the transport not only of KN1 but also of another mobile regulatory protein, TRANSPARENT TESTA GLABRA1 (TTG1). Our system could be easily adapted to reveal the mechanism underlying the selective transport of additional mobile signals through PD.
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12
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Kitagawa M, Wu P, Balkunde R, Cunniff P, Jackson D. An RNA exosome subunit mediates cell-to-cell trafficking of a homeobox mRNA via plasmodesmata. Science 2022; 375:177-182. [PMID: 35025667 DOI: 10.1126/science.abm0840] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Messenger RNAs (mRNAs) function as mobile signals for cell-to-cell communication in multicellular organisms. The KNOTTED1 (KN1) homeodomain family transcription factors act non–cell autonomously to control stem cell maintenance in plants through cell-to-cell movement of their proteins and mRNAs through plasmodesmata; however, the mechanism of mRNA movement is largely unknown. We show that cell-to-cell movement of a KN1 mRNA requires ribosomal RNA–processing protein 44A (AtRRP44A), a subunit of the RNA exosome that processes or degrades diverse RNAs in eukaryotes. AtRRP44A can interact with plasmodesmata and mediates the cell-to-cell trafficking of KN1 mRNA, and genetic analysis indicates that AtRRP44A is required for the developmental functions of SHOOT MERISTEMLESS, an Arabidopsis KN1 homolog. Our findings suggest that AtRRP44A promotes mRNA trafficking through plasmodesmata to control stem cell–dependent processes in plants.
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Affiliation(s)
| | - Peipei Wu
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | | | - Patrick Cunniff
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - David Jackson
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA.,National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, P.R. China
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13
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Doolabh K, Naidoo Y, Dewir YH, Al-Suhaibani N. Micromorphology, Ultrastructure and Histochemistry of Commelina benghalensis L. Leaves and Stems. PLANTS (BASEL, SWITZERLAND) 2021; 10:512. [PMID: 33803463 PMCID: PMC8000186 DOI: 10.3390/plants10030512] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 02/26/2021] [Accepted: 03/01/2021] [Indexed: 12/02/2022]
Abstract
Commelina benghalensis L. is used as a traditional medicine in treating numerous ailments and diseases such as infertility in women, conjunctivitis, gonorrhea, and jaundice. This study used light and electron microscopy coupled with histochemistry to investigate the micromorphology, ultrastructure and histochemical properties of C. benghalensis leaves and stems. Stereo and scanning electron microscopy revealed dense non-glandular trichomes on the leaves and stems and trichome density was greater in emergent leaves than in the young and mature. Three morphologically different non-glandular trichomes were observed including simple multicellular, simple bicellular and simple multicellular hooked. The simple bicellular trichomes were less common than the multicellular and hooked. Transmission electron micrographs showed mitochondria, vesicles and vacuoles in the trichome. The leaf section contained chloroplasts with plastoglobuli and starch grains. Histochemical analysis revealed various pharmacologically important compounds such as phenols, alkaloids, proteins and polysaccharides. The micromorphological and ultrastructural investigations suggest that Commelina benghalensis L. is an economically important medicinal plant due to bioactive compounds present in the leaves and stems.
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Affiliation(s)
- Kareshma Doolabh
- School of Life Sciences, University of KwaZulu-Natal, Westville, Private Bag X54001, Durban 4000, South Africa; (K.D.); (Y.N.)
| | - Yougasphree Naidoo
- School of Life Sciences, University of KwaZulu-Natal, Westville, Private Bag X54001, Durban 4000, South Africa; (K.D.); (Y.N.)
| | - Yaser Hassan Dewir
- Plant Production Department, PO Box 2460, College of Food and Agriculture Sciences, King Saud University, Riyadh 11451, Saudi Arabia;
- Department of Horticulture, Faculty of Agriculture, Kafrelsheikh University, Kafr El-Sheikh 33516, Egypt
| | - Nasser Al-Suhaibani
- Plant Production Department, PO Box 2460, College of Food and Agriculture Sciences, King Saud University, Riyadh 11451, Saudi Arabia;
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14
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Lopes FL, Galvan-Ampudia C, Landrein B. WUSCHEL in the shoot apical meristem: old player, new tricks. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:1527-1535. [PMID: 33332559 DOI: 10.1093/jxb/eraa572] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Accepted: 12/01/2020] [Indexed: 05/21/2023]
Abstract
The maintenance of the stem cell niche in the shoot apical meristem, the structure that generates all of the aerial organs of the plant, relies on a canonical feedback loop between WUSCHEL (WUS) and CLAVATA3 (CLV3). WUS is a homeodomain transcription factor expressed in the organizing centre that moves to the central zone to promote stem cell fate. CLV3 is a peptide whose expression is induced by WUS in the central zone and that can move back to the organizing centre to inhibit WUS expression. Within the past 20 years since the initial formulation of the CLV-WUS feedback loop, the mechanisms of stem cell maintenance have been intensively studied and the function of WUS has been redefined. In this review, we highlight the most recent advances in our comprehension of the molecular mechanisms of WUS function, of its interaction with other transcription factors and hormonal signals, and of its connection to environmental signals. Through this, we will show how WUS can integrate both internal and external cues to adapt meristem function to the plant environment.
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Affiliation(s)
- Filipa Lara Lopes
- Plant Stress Signaling, Instituto Gulbenkian de Ciência, Rua da Quinta Grande, Oeiras, Portugal
| | - Carlos Galvan-Ampudia
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, Ecole Normale Supérieure de Lyon, CNRS, INRAE, Lyon Cedex, France
| | - Benoit Landrein
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, Ecole Normale Supérieure de Lyon, CNRS, INRAE, Lyon Cedex, France
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15
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Wang Y, Liu X, Su H, Yin S, Han C, Hao D, Dong X. The regulatory mechanism of chilling-induced dormancy transition from endo-dormancy to non-dormancy in Polygonatum kingianum Coll.et Hemsl rhizome bud. PLANT MOLECULAR BIOLOGY 2019; 99:205-217. [PMID: 30627860 DOI: 10.1007/s11103-018-0812-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2018] [Accepted: 12/11/2018] [Indexed: 05/27/2023]
Abstract
We identified three dormant stages of Polygonatum kingianum and changes that occurred during dormancy transition in the following aspects including cell wall and hormones, as well as interaction among them. Polygonatum kingianum Coll.et Hemsl (P. kingianum) is an important traditional Chinese medicine, but the mechanism of its rhizome bud dormancy has not yet been studied systematically. In this study, three dormancy phases were induced under controlled conditions, and changes occurring during the transition were examined, focusing on phytohormones and the cell wall. As revealed by HPLC-MS (High Performance Liquid Chromatography-Mass Spectrometry) analysis, the endo- to non-dormancy transition was association with a reduced abscisic acid (ABA)/gibberellin (GA3) ratio, a decreased level of auxin (IAA) and an increased level of trans-zeatin (tZR). Transmission electron microscopy showed that plasmodesmata (PDs) and the cell wall of the bud underwent significant changes between endo- and eco-dormancy. A total of 95,462 differentially expressed genes (DEGs) were identified based on transcriptomics, and clustering and principal component analysis confirmed the different physiological statuses of the three types of bud samples. Changes in the abundance of transcripts associated with IAA, cytokinins (CTKs), GA, ABA, brassinolide (BR), jasmonic acid (JA), ethylene, salicylic acid (SA), PDs and cell wall-loosening factors were analysed during the bud dormancy transition in P. kingianum. Furthermore, nitrilase 4 (NIT4) and tryptophan synthase alpha chain (TSA1), which are related to IAA synthesis, were identified as hub genes of the co-expression network, and strong interactions between hormones and cell wall-related factors were observed. This research will provide a good model for chilling-treated rhizome bud dormancy in P. kingianum and cultivation of this plant.
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Affiliation(s)
- Yue Wang
- College of Agronomy and Biotechnology, China Agricultural University, No. 2 Yuanmingyuan West Road, Beijing, China
| | - Xiaoqing Liu
- College of Agronomy and Biotechnology, China Agricultural University, No. 2 Yuanmingyuan West Road, Beijing, China
| | - He Su
- College of Agronomy and Biotechnology, China Agricultural University, No. 2 Yuanmingyuan West Road, Beijing, China
| | - Shikai Yin
- College of Agronomy and Biotechnology, China Agricultural University, No. 2 Yuanmingyuan West Road, Beijing, China
| | - Caixia Han
- College of Agronomy and Biotechnology, China Agricultural University, No. 2 Yuanmingyuan West Road, Beijing, China
| | - Dandan Hao
- College of Agronomy and Biotechnology, China Agricultural University, No. 2 Yuanmingyuan West Road, Beijing, China
| | - Xuehui Dong
- College of Agronomy and Biotechnology, China Agricultural University, No. 2 Yuanmingyuan West Road, Beijing, China.
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16
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Cui X, Zhang Z, Wang Y, Wu J, Han X, Gu X, Lu T. TWI1 regulates cell-to-cell movement of OSH15 to control leaf cell fate. THE NEW PHYTOLOGIST 2019; 221:326-340. [PMID: 30151833 DOI: 10.1111/nph.15390] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 07/01/2018] [Indexed: 06/08/2023]
Abstract
Cell pattern formation in plant leaves has attracted much attention from both plant biologists and breeders. However, in rice, the molecular mechanism remains unclear. Here, we describe the isolation and functional characterization of TWISTED-LEAF1 (TWI1), a critical gene involved in the development of the mestome sheath, vascular bundle sheath, interveinal mesophyll and sclerenchyma in rice leaves. Mutant twi1 plants have twisted leaves which might be caused by the compromised development and disordered patterning of bundle sheath, sclerenchyma and interveinal mesophyll cells. Expression of TWI1 can functionally rescue these mutant phenotypes. TWI1 encodes a transcription factor binding protein that interacts with OSH15, a class I KNOTTED1-like homeobox (KNOX) transcription factor. The cell-to-cell trafficking of OSH15 is restricted through its interaction with TWI1. Knockout or knockdown of OSH15 in twi1 rescues the twisted leaf phenotype. These studies reveal a key factor controlling cell pattern formation in rice leaves.
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Affiliation(s)
- Xuean Cui
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Zhiguo Zhang
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Yanwei Wang
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Jinxia Wu
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Xiao Han
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Xiaofeng Gu
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Tiegang Lu
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
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17
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Liu L, Li C, Song S, Teo ZWN, Shen L, Wang Y, Jackson D, Yu H. FTIP-Dependent STM Trafficking Regulates Shoot Meristem Development in Arabidopsis. Cell Rep 2018; 23:1879-1890. [DOI: 10.1016/j.celrep.2018.04.033] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2017] [Revised: 12/04/2017] [Accepted: 04/05/2018] [Indexed: 10/16/2022] Open
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18
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Kehr J, Kragler F. Long distance RNA movement. THE NEW PHYTOLOGIST 2018; 218:29-40. [PMID: 29418002 DOI: 10.1111/nph.15025] [Citation(s) in RCA: 108] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 12/28/2017] [Indexed: 05/06/2023]
Abstract
Contents Summary 29 I. Introduction 29 II. Phloem as a conduit for macromolecules 30 III. Classes of phloem transported RNAs and their function 32 IV. Mode of RNA transport 35 V. Conclusions 37 Acknowledgements 37 References 37 SUMMARY: In higher plants, small noncoding RNAs and large messenger RNA (mRNA) molecules are transported between cells and over long distances via the phloem. These large macromolecules are thought to get access to the sugar-conducting phloem vessels via specialized plasmodesmata (PD). Analyses of the phloem exudate suggest that all classes of RNA molecules, including silencing-induced RNAs (siRNAs), micro RNAs (miRNAs), transfer RNAs (tRNAs), ribosomal RNA (rRNAs) and mRNAs, are transported via the vasculature to distant tissues. Although the functions of mobile siRNAs and miRNAs as signalling molecules are well established, we lack a profound understanding of mobile mRNA function(s) in recipient cells and tissues, and how they are selected for transport. A surprisingly high number of up to thousands of mRNAs were described in diverse plant species such as cucumber, pumpkin, Arabidopsis and grapevine to move long distances over graft junctions to distinct body parts. In this review, we present an overview of the classes of mobile RNAs, the potential mechanisms facilitating RNA long-distance transport, and the roles of mobile RNAs in regulating transcription and translation. Furthermore, we address potential function(s) of mobile protein-encoding mRNAs with respect to their characteristics and evolutionary constraints.
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Affiliation(s)
- Julia Kehr
- Biocenter Klein Flottbek, Molekulare Pflanzengenetik, University Hamburg, Ohnhorststr. 18, Hamburg 22609, Germany
| | - Friedrich Kragler
- Department II, Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, Potsdam-Golm 14476, Germany
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19
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Spiegelman Z, Lee CM, Gallagher KL. KinG Is a Plant-Specific Kinesin That Regulates Both Intra- and Intercellular Movement of SHORT-ROOT. PLANT PHYSIOLOGY 2018; 176:392-405. [PMID: 29122988 PMCID: PMC5761801 DOI: 10.1104/pp.17.01518] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 11/06/2017] [Indexed: 05/09/2023]
Abstract
Both endogenous plant proteins and viral movement proteins associate with microtubules to promote their movement through plasmodesmata. The association of viral movement proteins with microtubules facilitates the formation of virus-associated replication complexes, which are required for the amplification and subsequent spread of the virus. However, the role of microtubules in the intercellular movement of plant proteins is less clear. Here we show that the SHORT-ROOT (SHR) protein, which moves between cells in the root to regulate root radial patterning, interacts with a type-14 kinesin, KINESIN G (KinG). KinG is a calponin homology domain kinesin that directly interacts with the SHR-binding protein SIEL (SHR-INTERACING EMBRYONIC LETHAL) and localizes to both microtubules and actin. Since SIEL and SHR associate with endosomes, we suggest that KinG serves as a linker between SIEL, SHR, and the plant cytoskeleton. Loss of KinG function results in a decrease in the intercellular movement of SHR and an increase in the sensitivity of SHR movement to treatment with oryzalin. Examination of SHR and KinG localization and dynamics in live cells suggests that KinG is a nonmotile kinesin that promotes the pausing of SHR-associated endosomes. We suggest a model in which interaction of KinG with SHR allows for the formation of stable movement complexes that facilitate the cell-to-cell transport of SHR.
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Affiliation(s)
- Ziv Spiegelman
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Chin-Mei Lee
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Kimberly L Gallagher
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104
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20
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Alhajturki D, Muralidharan S, Nurmi M, Rowan BA, Lunn JE, Boldt H, Salem MA, Alseekh S, Jorzig C, Feil R, Giavalisco P, Fernie AR, Weigel D, Laitinen RAE. Dose-dependent interactions between two loci trigger altered shoot growth in BG-5 × Krotzenburg-0 (Kro-0) hybrids of Arabidopsis thaliana. THE NEW PHYTOLOGIST 2018; 217:392-406. [PMID: 28906562 DOI: 10.1111/nph.14781] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Accepted: 08/06/2017] [Indexed: 06/07/2023]
Abstract
Hybrids occasionally exhibit genetic interactions resulting in reduced fitness in comparison to their parents. Studies of Arabidopsis thaliana have highlighted the role of immune conflicts, but less is known about the role of other factors in hybrid incompatibility in plants. Here, we present a new hybrid incompatibility phenomenon in this species. We have characterized a new case of F1 hybrid incompatibility from a cross between the A. thaliana accessions Krotzenburg-0 (Kro-0) and BG-5, by conducting transcript, metabolite and hormone analyses, and identified the causal loci through genetic mapping. The F1 hybrids showed arrested growth of the main stem, altered shoot architecture, and altered concentrations of hormones in comparison to parents. The F1 phenotype could be rescued in a developmental-stage-dependent manner by shifting to a higher growth temperature. These F1 phenotypes were linked to two loci, one on chromosome 2 and one on chromosome 3. The F2 generation segregated plants with more severe phenotypes which were linked to the same loci as those in the F1 . This study provides novel insights into how previously unknown mechanisms controlling shoot branching and stem growth can result in hybrid incompatibility.
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Affiliation(s)
- Dema Alhajturki
- Max Planck Institute of Molecular Plant Physiology, 14476, Potsdam, Germany
| | | | - Markus Nurmi
- Max Planck Institute of Molecular Plant Physiology, 14476, Potsdam, Germany
| | - Beth A Rowan
- Max Planck Institute for Developmental Biology, 72076, Tübingen, Germany
| | - John E Lunn
- Max Planck Institute of Molecular Plant Physiology, 14476, Potsdam, Germany
| | - Helena Boldt
- Max Planck Institute for Developmental Biology, 72076, Tübingen, Germany
| | - Mohamed A Salem
- Max Planck Institute of Molecular Plant Physiology, 14476, Potsdam, Germany
- Department of Pharmacognosy, Faculty of Pharmacy, Cairo University, Cairo, 11562, Egypt
| | - Saleh Alseekh
- Max Planck Institute of Molecular Plant Physiology, 14476, Potsdam, Germany
| | - Christian Jorzig
- Max Planck Institute of Molecular Plant Physiology, 14476, Potsdam, Germany
| | - Regina Feil
- Max Planck Institute of Molecular Plant Physiology, 14476, Potsdam, Germany
| | - Patrick Giavalisco
- Max Planck Institute of Molecular Plant Physiology, 14476, Potsdam, Germany
| | - Alisdair R Fernie
- Max Planck Institute of Molecular Plant Physiology, 14476, Potsdam, Germany
| | - Detlef Weigel
- Max Planck Institute for Developmental Biology, 72076, Tübingen, Germany
| | - Roosa A E Laitinen
- Max Planck Institute of Molecular Plant Physiology, 14476, Potsdam, Germany
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21
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Munien P, Naidoo Y, Naidoo G. Micromorphology, histochemistry and ultrastructure of the foliar trichomes of Withania somnifera (L.) Dunal (Solanaceae). PLANTA 2015; 242:1107-22. [PMID: 26063189 DOI: 10.1007/s00425-015-2341-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 05/28/2015] [Indexed: 05/11/2023]
Abstract
The leaves of Withania somnifera contained four morphologically distinct trichome types: glandular capitate, non-glandular dendritic (branched), non-glandular bicellular and non-glandular multicellular trichomes. Major phytochemical compounds present within glandular and non-glandular trichomes were alkaloids and phenolic compounds. The aim of this study was to characterize the micromorphology of the foliar trichomes of Withania somnifera as well as to elucidate the location and composition of the secretory products. Trichome density and length was also determined in three developmental stages of the leaves. Light microscopy and scanning electron microscopy showed the presence of four morphologically distinct trichome types: glandular capitate, non-glandular dendritic, non-glandular bicellular and non-glandular multicellular. The dendritic trichomes exhibited cuticular warts which are involved in the "Lotus-Effect". Glandular capitate and non-glandular dendritic trichomes were aggregated on the mid-vein of young and mature leaves, possibly to protect underlying vasculature. Histochemical staining also revealed the presence of two major classes of phytochemical compounds that are of medicinal importance, i.e. alkaloids and phenolic compounds. These compounds are used to treat a wide variety of ailments and also act as chemical deterrents in plants. The results of this study explain possible roles of four morphologically distinct trichome types based on their morphology, foliar distribution and content.
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Affiliation(s)
- Prelina Munien
- School of Life Sciences, University of KwaZulu-Natal, P/Bag X54001, Durban, 4000, South Africa.
| | - Yougasphree Naidoo
- School of Life Sciences, University of KwaZulu-Natal, P/Bag X54001, Durban, 4000, South Africa.
| | - Gonasageran Naidoo
- School of Life Sciences, University of KwaZulu-Natal, P/Bag X54001, Durban, 4000, South Africa
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22
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Gallagher KL, Sozzani R, Lee CM. Intercellular protein movement: deciphering the language of development. Annu Rev Cell Dev Biol 2015; 30:207-33. [PMID: 25288113 DOI: 10.1146/annurev-cellbio-100913-012915] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Development in multicellular organisms requires the coordinated production of a large number of specialized cell types through sophisticated signaling mechanisms. Non-cell-autonomous signals are one of the key mechanisms by which organisms coordinate development. In plants, intercellular movement of transcription factors and other mobile signals, such as hormones and peptides, is essential for normal development. Through a combination of different approaches, a large number of non-cell-autonomous signals that control plant development have been identified. We review some of the transcriptional regulators that traffic between cells, as well as how changes in symplasmic continuity affect and are affected by development. We also review current models for how mobile signals move via plasmodesmata and how movement is inhibited. Finally, we consider challenges in and new tools for studying protein movement.
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Affiliation(s)
- Kimberly L Gallagher
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104; ,
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23
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Plant virus replication and movement. Virology 2015; 479-480:657-71. [DOI: 10.1016/j.virol.2015.01.025] [Citation(s) in RCA: 136] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 01/19/2015] [Accepted: 01/28/2015] [Indexed: 01/10/2023]
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24
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Huang W, Pitorre D, Poretska O, Marizzi C, Winter N, Poppenberger B, Sieberer T. ALTERED MERISTEM PROGRAM1 suppresses ectopic stem cell niche formation in the shoot apical meristem in a largely cytokinin-independent manner. PLANT PHYSIOLOGY 2015; 167:1471-86. [PMID: 25673776 PMCID: PMC4378165 DOI: 10.1104/pp.114.254623] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Accepted: 02/09/2015] [Indexed: 05/03/2023]
Abstract
Plants are able to reiteratively form new organs in an environmentally adaptive manner during postembryonic development. Organ formation in plants is dependent on stem cell niches (SCNs), which are located in the so-called meristems. Meristems show a functional zonation along the apical-basal axis and the radial axis. Shoot apical meristems of higher plants are dome-like structures, which contain a central SCN that consists of an apical stem cell pool and an underlying organizing center. Organ primordia are formed in the circular peripheral zone (PZ) from stem cell descendants in which differentiation programs are activated. One mechanism to keep this radial symmetry integrated is that the existing SCN actively suppresses stem cell identity in the PZ. However, how this lateral inhibition system works at the molecular level is far from understood. Here, we show that a defect in the putative carboxypeptidase ALTERED MERISTEM PROGRAM1 (AMP1) causes the formation of extra SCNs in the presence of an intact primary shoot apical meristem, which at least partially contributes to the enhanced shoot meristem size and leaf initiation rate found in the mutant. This defect appears to be neither a specific consequence of the altered cytokinin levels in amp1 nor directly mediated by the WUSCHEL/CLAVATA feedback loop. De novo formation of supernumerary stem cell pools was further enhanced in plants mutated in both AMP1 and its paralog LIKE AMP1, indicating that they exhibit partially overlapping roles to suppress SCN respecification in the PZ.
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Affiliation(s)
- Wenwen Huang
- Department of Microbiology, Immunobiology and Genetics, Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria (W.H., D.P., O.P., C.M., N.W., B.P., T.S.); andResearch Unit Plant Growth Regulation (O.P., T.S.) and Biotechnology of Horticultural Crops (B.P.), TUM School of Life Sciences Weihenstephan, Technische Universität München, D-85354 Freising, Germany
| | - Delphine Pitorre
- Department of Microbiology, Immunobiology and Genetics, Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria (W.H., D.P., O.P., C.M., N.W., B.P., T.S.); andResearch Unit Plant Growth Regulation (O.P., T.S.) and Biotechnology of Horticultural Crops (B.P.), TUM School of Life Sciences Weihenstephan, Technische Universität München, D-85354 Freising, Germany
| | - Olena Poretska
- Department of Microbiology, Immunobiology and Genetics, Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria (W.H., D.P., O.P., C.M., N.W., B.P., T.S.); andResearch Unit Plant Growth Regulation (O.P., T.S.) and Biotechnology of Horticultural Crops (B.P.), TUM School of Life Sciences Weihenstephan, Technische Universität München, D-85354 Freising, Germany
| | - Christine Marizzi
- Department of Microbiology, Immunobiology and Genetics, Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria (W.H., D.P., O.P., C.M., N.W., B.P., T.S.); andResearch Unit Plant Growth Regulation (O.P., T.S.) and Biotechnology of Horticultural Crops (B.P.), TUM School of Life Sciences Weihenstephan, Technische Universität München, D-85354 Freising, Germany
| | - Nikola Winter
- Department of Microbiology, Immunobiology and Genetics, Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria (W.H., D.P., O.P., C.M., N.W., B.P., T.S.); andResearch Unit Plant Growth Regulation (O.P., T.S.) and Biotechnology of Horticultural Crops (B.P.), TUM School of Life Sciences Weihenstephan, Technische Universität München, D-85354 Freising, Germany
| | - Brigitte Poppenberger
- Department of Microbiology, Immunobiology and Genetics, Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria (W.H., D.P., O.P., C.M., N.W., B.P., T.S.); andResearch Unit Plant Growth Regulation (O.P., T.S.) and Biotechnology of Horticultural Crops (B.P.), TUM School of Life Sciences Weihenstephan, Technische Universität München, D-85354 Freising, Germany
| | - Tobias Sieberer
- Department of Microbiology, Immunobiology and Genetics, Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria (W.H., D.P., O.P., C.M., N.W., B.P., T.S.); andResearch Unit Plant Growth Regulation (O.P., T.S.) and Biotechnology of Horticultural Crops (B.P.), TUM School of Life Sciences Weihenstephan, Technische Universität München, D-85354 Freising, Germany
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25
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Aguilar-Martínez JA, Uchida N, Townsley B, West DA, Yanez A, Lynn N, Kimura S, Sinha N. Transcriptional, posttranscriptional, and posttranslational regulation of SHOOT MERISTEMLESS gene expression in Arabidopsis determines gene function in the shoot apex. PLANT PHYSIOLOGY 2015; 167:424-42. [PMID: 25524441 PMCID: PMC4326739 DOI: 10.1104/pp.114.248625] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 12/12/2014] [Indexed: 05/21/2023]
Abstract
The activity of SHOOT MERISTEMLESS (STM) is required for the functioning of the shoot apical meristem (SAM). STM is expressed in the SAM but is down-regulated at the site of leaf initiation. STM is also required for the formation of compound leaves. However, how the activity of STM is regulated at the transcriptional, posttranscriptional, and posttranslational levels is poorly understood. We previously found two conserved noncoding sequences in the promoters of STM-like genes across angiosperms, the K-box and the RB-box. Here, we characterize the function of the RB-box in Arabidopsis (Arabidopsis thaliana). The RB-box, along with the K-box, regulates the expression of STM in leaf sinuses, which are areas on the leaf blade with meristematic potential. The RB-box also contributes to restrict STM expression to the SAM. We identified FAR1-RELATED SEQUENCES-RELATED FACTOR1 (FRF1) as a binding factor to the RB-box region. FRF1 is an uncharacterized member of a subfamily of four truncated proteins related to the FAR1-RELATED SEQUENCES factors. Internal deletion analysis of the STM promoter identified a region required to repress the expression of STM in hypocotyls. Expression of STM in leaf primordia under the control of the JAGGED promoter produced plants with partially undifferentiated leaves. We further found that the ELK domain has a role in the posttranslational regulation of STM by affecting the nuclear localization of STM.
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Affiliation(s)
- José Antonio Aguilar-Martínez
- Department of Plant Biology, University of California, Davis, California 95616 (J.A.A.-M., N.U., B.T., D.A.W., A.Y., N.L., S.K., N.S.);World Premier International Research Center Initiative-Institute of Transformative Bio-Molecules, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan (N.U.); andDepartment of Bioresource and Environmental Sciences, Kyoto Sangyo University, Kyoto 603-8555, Japan (S.K.)
| | - Naoyuki Uchida
- Department of Plant Biology, University of California, Davis, California 95616 (J.A.A.-M., N.U., B.T., D.A.W., A.Y., N.L., S.K., N.S.);World Premier International Research Center Initiative-Institute of Transformative Bio-Molecules, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan (N.U.); andDepartment of Bioresource and Environmental Sciences, Kyoto Sangyo University, Kyoto 603-8555, Japan (S.K.)
| | - Brad Townsley
- Department of Plant Biology, University of California, Davis, California 95616 (J.A.A.-M., N.U., B.T., D.A.W., A.Y., N.L., S.K., N.S.);World Premier International Research Center Initiative-Institute of Transformative Bio-Molecules, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan (N.U.); andDepartment of Bioresource and Environmental Sciences, Kyoto Sangyo University, Kyoto 603-8555, Japan (S.K.)
| | - Donnelly Ann West
- Department of Plant Biology, University of California, Davis, California 95616 (J.A.A.-M., N.U., B.T., D.A.W., A.Y., N.L., S.K., N.S.);World Premier International Research Center Initiative-Institute of Transformative Bio-Molecules, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan (N.U.); andDepartment of Bioresource and Environmental Sciences, Kyoto Sangyo University, Kyoto 603-8555, Japan (S.K.)
| | - Andrea Yanez
- Department of Plant Biology, University of California, Davis, California 95616 (J.A.A.-M., N.U., B.T., D.A.W., A.Y., N.L., S.K., N.S.);World Premier International Research Center Initiative-Institute of Transformative Bio-Molecules, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan (N.U.); andDepartment of Bioresource and Environmental Sciences, Kyoto Sangyo University, Kyoto 603-8555, Japan (S.K.)
| | - Nafeesa Lynn
- Department of Plant Biology, University of California, Davis, California 95616 (J.A.A.-M., N.U., B.T., D.A.W., A.Y., N.L., S.K., N.S.);World Premier International Research Center Initiative-Institute of Transformative Bio-Molecules, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan (N.U.); andDepartment of Bioresource and Environmental Sciences, Kyoto Sangyo University, Kyoto 603-8555, Japan (S.K.)
| | - Seisuke Kimura
- Department of Plant Biology, University of California, Davis, California 95616 (J.A.A.-M., N.U., B.T., D.A.W., A.Y., N.L., S.K., N.S.);World Premier International Research Center Initiative-Institute of Transformative Bio-Molecules, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan (N.U.); andDepartment of Bioresource and Environmental Sciences, Kyoto Sangyo University, Kyoto 603-8555, Japan (S.K.)
| | - Neelima Sinha
- Department of Plant Biology, University of California, Davis, California 95616 (J.A.A.-M., N.U., B.T., D.A.W., A.Y., N.L., S.K., N.S.);World Premier International Research Center Initiative-Institute of Transformative Bio-Molecules, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan (N.U.); andDepartment of Bioresource and Environmental Sciences, Kyoto Sangyo University, Kyoto 603-8555, Japan (S.K.)
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Abstract
The symplastic communication network established by plasmodesmata (PD) and connected phloem provides an essential pathway for spatiotemporal intercellular signaling in plant development but is also exploited by viruses for moving their genomes between cells in order to infect plants systemically. Virus movement depends on virus-encoded movement proteins (MPs) that target PD and therefore represent important keys to the cellular mechanisms underlying the intercellular trafficking of viruses and other macromolecules. Viruses and their MPs have evolved different mechanisms for intracellular transport and interaction with PD. Some viruses move from cell to cell by interacting with cellular mechanisms that control the size exclusion limit of PD whereas other viruses alter the PD architecture through assembly of specialized transport structures within the channel. Some viruses move between cells in the form of assembled virus particles whereas other viruses may interact with nucleic acid transport mechanisms to move their genomes in a non-encapsidated form. Moreover, whereas several viruses rely on the secretory pathway to target PD, other viruses interact with the cortical endoplasmic reticulum and associated cytoskeleton to spread infection. This chapter provides an introduction into viruses and their role in studying the diverse cellular mechanisms involved in intercellular PD-mediated macromolecular trafficking.
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Affiliation(s)
- Manfred Heinlein
- Institut de Biologie Moléculaire des Plantes (IBMP), Centre National de la Recherche Scientifique (CNRS), 12 rue du Général Zimmer, 67084, Strasbourg, France,
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Kumar D, Kumar R, Hyun TK, Kim JY. Cell-to-cell movement of viruses via plasmodesmata. JOURNAL OF PLANT RESEARCH 2015; 128:37-47. [PMID: 25527904 DOI: 10.1007/s10265-014-0683-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 10/14/2014] [Indexed: 05/03/2023]
Abstract
Plant viruses utilize plasmodesmata (PD), unique membrane-lined cytoplasmic nanobridges in plants, to spread infection cell-to-cell and long-distance. Such invasion involves a range of regulatory mechanisms to target and modify PD. Exciting discoveries in this field suggest that these mechanisms are executed by the interaction between plant cellular components and viral movement proteins (MPs) or other virus-encoded factors. Striking working analogies exist among endogenous non-cell-autonomous proteins and viral MPs, in which not only do they all use PD to traffic, but also they exploit same regulatory components to exert their functions. Thus, this review discusses on the viral strategies to move via PD and the PD-regulatory mechanisms involved in viral pathogenesis.
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Affiliation(s)
- Dhinesh Kumar
- Division of Applied Life Science (BK21plus), Department of Biochemistry, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, 27-306, 501 Jinju-Daero, Jinju, 660-701, Korea
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28
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Chen H, Jackson D, Kim JY. Identification of evolutionarily conserved amino acid residues in homeodomain of KNOX proteins for intercellular trafficking. PLANT SIGNALING & BEHAVIOR 2014; 9:e28355. [PMID: 24603432 PMCID: PMC4091555 DOI: 10.4161/psb.28355] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2014] [Revised: 02/25/2014] [Accepted: 02/25/2014] [Indexed: 06/03/2023]
Abstract
Maize knotted (KN1) homeodomain (HD) protein is a well-known mobile transcription factor crucial for stem cell maintenance. Recent studies have revealed that the trihelical HD of knotted1-like homeobox (KNOX) proteins is necessary and sufficient for selective cell-to-cell trafficking. Also, the efficient trafficking ability for HD is likely to be acquired during the evolution of early nonvascular land plants. Here, using the point-mutated HD of KN1 and shoot meristemless (STM) in the trichome rescue system, together with molecular structure modeling, we have found the evolutionarily conserved amino acid residues, such as arginine in helix α1 and leucine in helix α3, which are essential for intercellular trafficking. Our studies provided important clues for the 3-dimensional protein structure required for cell-to-cell movement of non-cell-autonomous transcription factors.
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Affiliation(s)
- Huan Chen
- Division of Applied Life Science (BK21plus); Plant Molecular Biology & Biotechnology Research Center; Gyeongsang National University; Jinju, Korea
| | - David Jackson
- Cold Spring Harbor Laboratory; Cold Spring Harbor, NY USA
| | - Jae-Yean Kim
- Division of Applied Life Science (BK21plus); Plant Molecular Biology & Biotechnology Research Center; Gyeongsang National University; Jinju, Korea
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29
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Hamada T. Microtubule organization and microtubule-associated proteins in plant cells. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2014; 312:1-52. [PMID: 25262237 DOI: 10.1016/b978-0-12-800178-3.00001-4] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Plants have unique microtubule (MT) arrays, cortical MTs, preprophase band, mitotic spindle, and phragmoplast, in the processes of evolution. These MT arrays control the directions of cell division and expansion especially in plants and are essential for plant morphogenesis and developments. Organizations and functions of these MT arrays are accomplished by diverse MT-associated proteins (MAPs). This review introduces 10 of conserved MAPs in eukaryote such as γ-TuC, augmin, katanin, kinesin, EB1, CLASP, MOR1/MAP215, MAP65, TPX2, formin, and several plant-specific MAPs such as CSI1, SPR2, MAP70, WVD2/WDL, RIP/MIDD, SPR1, MAP18/PCaP, EDE1, and MAP190. Most of the studies cited in this review have been analyzed in the particular model plant, Arabidopsis thaliana. The significant knowledge of A. thaliana is the important established base to understand MT organizations and functions in plants.
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Affiliation(s)
- Takahiro Hamada
- Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Tokyo, Japan.
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30
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Yoo SC, Chen C, Rojas M, Daimon Y, Ham BK, Araki T, Lucas WJ. Phloem long-distance delivery of FLOWERING LOCUS T (FT) to the apex. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 75:456-68. [PMID: 23607279 DOI: 10.1111/tpj.12213] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 04/05/2013] [Accepted: 04/16/2013] [Indexed: 05/05/2023]
Abstract
Cucurbita moschata FLOWERING LOCUS T-LIKE 2 (hereafter FTL2) and Arabidopsis thaliana (Arabidopsis) FLOWERING LOCUS T (FT), components of the plant florigenic signaling system, move long-distance through the phloem from source leaves to the vegetative apex where they mediate floral induction. The mechanisms involved in long-distance trafficking of FT/FTL2 remain to be elucidated. In this study, we identified the critical motifs on both FT and FTL2 required for cell-to-cell trafficking through mutant analyses using a zucchini yellow mosaic virus expression vector. Western blot analysis, performed on phloem sap collected from just beneath the vegetative apex of C. moschata plants, established that all mutant proteins tested retained the ability to enter the phloem translocation stream. However, immunolocalization studies revealed that a number of these FTL2/FT mutants were defective in the post-phloem zone, suggesting that a regulation mechanism for FT trafficking exists in the post-phloem unloading step. The selective movements of FT/FTL2 were further observed by microinjection and trichome rescue studies, which revealed that FT/FTL2 has the ability to dilate plasmodesmata microchannels during the process of cell-to-cell trafficking, and various mutants were compromised in their capacity to traffic through plasmodesmata. Based on these findings, a model is presented to account for the mechanism by which FT/FTL2 enters the phloem translocation stream and subsequently exits the phloem and enters the apical tissue, where it initiates the vegetative to floral transition.
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Affiliation(s)
- Soo-Cheul Yoo
- Department of Plant Biology, University of California, Davis, CA 95616, USA
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31
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Niehl A, Peña EJ, Amari K, Heinlein M. Microtubules in viral replication and transport. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 75:290-308. [PMID: 23379770 DOI: 10.1111/tpj.12134] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2012] [Revised: 01/29/2013] [Accepted: 01/31/2013] [Indexed: 05/05/2023]
Abstract
Viruses use and subvert host cell mechanisms to support their replication and spread between cells, tissues and organisms. Microtubules and associated motor proteins play important roles in these processes in animal systems, and may also play a role in plants. Although transport processes in plants are mostly actin based, studies, in particular with Tobacco mosaic virus (TMV) and its movement protein (MP), indicate direct or indirect roles of microtubules in the cell-to-cell spread of infection. Detailed observations suggest that microtubules participate in the cortical anchorage of viral replication complexes, in guiding their trafficking along the endoplasmic reticulum (ER)/actin network, and also in developing the complexes into virus factories. Microtubules also play a role in the plant-to-plant transmission of Cauliflower mosaic virus (CaMV) by assisting in the development of specific virus-induced inclusions that facilitate viral uptake by aphids. The involvement of microtubules in the formation of virus factories and of other virus-induced inclusions suggests the existence of aggresomal pathways by which plant cells recruit membranes and proteins into localized macromolecular assemblies. Although studies related to the involvement of microtubules in the interaction of viruses with plants focus on specific virus models, a number of observations with other virus species suggest that microtubules may have a widespread role in viral pathogenesis.
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Affiliation(s)
- Annette Niehl
- Zürich-Basel Plant Science Center, Botany, Department of Environmental Sciences, University of Basel, Hebelstrasse 1, CH-4056 Basel, Switzerland
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32
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Di Giacomo E, Iannelli MA, Frugis G. TALE and Shape: How to Make a Leaf Different. PLANTS (BASEL, SWITZERLAND) 2013. [PMID: 27137378 DOI: 10.3390/plantas2020317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The Three Amino acid Loop Extension (TALE) proteins constitute an ancestral superclass of homeodomain transcription factors conserved in animals, plants and fungi. In plants they comprise two classes, KNOTTED1-LIKE homeobox (KNOX) and BEL1-like homeobox (BLH or BELL, hereafter referred to as BLH), which are involved in shoot apical meristem (SAM) function, as well as in the determination and morphological development of leaves, stems and inflorescences. Selective protein-protein interactions between KNOXs and BLHs affect heterodimer subcellular localization and target affinity. KNOXs exert their roles by maintaining a proper balance between undifferentiated and differentiated cell state through the modulation of multiple hormonal pathways. A pivotal function of KNOX in evolutionary diversification of leaf morphology has been assessed. In the SAM of both simple- and compound-leafed seed species, downregulation of most class 1 KNOX (KNOX1) genes marks the sites of leaf primordia initiation. However, KNOX1 expression is re-established during leaf primordia development of compound-leafed species to maintain transient indeterminacy and morphogenetic activity at the leaf margins. Despite the increasing knowledge available about KNOX1 protein function in plant development, a comprehensive view on their downstream effectors remains elusive. This review highlights the role of TALE proteins in leaf initiation and morphological plasticity with a focus on recent advances in the identification of downstream target genes and pathways.
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Affiliation(s)
- Elisabetta Di Giacomo
- Istituto di Biologia e Biotecnologia Agraria, UOS Roma, Consiglio Nazionale delle Ricerche, Via Salaria Km. 29,300, Monterotondo Scalo, 00015 Roma, Italy.
| | - Maria Adelaide Iannelli
- Istituto di Biologia e Biotecnologia Agraria, UOS Roma, Consiglio Nazionale delle Ricerche, Via Salaria Km. 29,300, Monterotondo Scalo, 00015 Roma, Italy.
| | - Giovanna Frugis
- Istituto di Biologia e Biotecnologia Agraria, UOS Roma, Consiglio Nazionale delle Ricerche, Via Salaria Km. 29,300, Monterotondo Scalo, 00015 Roma, Italy.
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33
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Di Giacomo E, Iannelli MA, Frugis G. TALE and Shape: How to Make a Leaf Different. PLANTS 2013; 2:317-42. [PMID: 27137378 PMCID: PMC4844364 DOI: 10.3390/plants2020317] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 04/10/2013] [Accepted: 04/19/2013] [Indexed: 11/25/2022]
Abstract
The Three Amino acid Loop Extension (TALE) proteins constitute an ancestral superclass of homeodomain transcription factors conserved in animals, plants and fungi. In plants they comprise two classes, KNOTTED1-LIKE homeobox (KNOX) and BEL1-like homeobox (BLH or BELL, hereafter referred to as BLH), which are involved in shoot apical meristem (SAM) function, as well as in the determination and morphological development of leaves, stems and inflorescences. Selective protein-protein interactions between KNOXs and BLHs affect heterodimer subcellular localization and target affinity. KNOXs exert their roles by maintaining a proper balance between undifferentiated and differentiated cell state through the modulation of multiple hormonal pathways. A pivotal function of KNOX in evolutionary diversification of leaf morphology has been assessed. In the SAM of both simple- and compound-leafed seed species, downregulation of most class 1 KNOX (KNOX1) genes marks the sites of leaf primordia initiation. However, KNOX1 expression is re-established during leaf primordia development of compound-leafed species to maintain transient indeterminacy and morphogenetic activity at the leaf margins. Despite the increasing knowledge available about KNOX1 protein function in plant development, a comprehensive view on their downstream effectors remains elusive. This review highlights the role of TALE proteins in leaf initiation and morphological plasticity with a focus on recent advances in the identification of downstream target genes and pathways.
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Affiliation(s)
- Elisabetta Di Giacomo
- Istituto di Biologia e Biotecnologia Agraria, UOS Roma, Consiglio Nazionale delle Ricerche, Via Salaria Km. 29,300, Monterotondo Scalo, 00015 Roma, Italy.
| | - Maria Adelaide Iannelli
- Istituto di Biologia e Biotecnologia Agraria, UOS Roma, Consiglio Nazionale delle Ricerche, Via Salaria Km. 29,300, Monterotondo Scalo, 00015 Roma, Italy.
| | - Giovanna Frugis
- Istituto di Biologia e Biotecnologia Agraria, UOS Roma, Consiglio Nazionale delle Ricerche, Via Salaria Km. 29,300, Monterotondo Scalo, 00015 Roma, Italy.
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34
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Wu S, Gallagher KL. Intact microtubules are required for the intercellular movement of the SHORT-ROOT transcription factor. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 74:148-159. [PMID: 23294290 DOI: 10.1111/tpj.12112] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Revised: 12/11/2012] [Accepted: 01/02/2013] [Indexed: 05/28/2023]
Abstract
In both plants and animals, cell-to-cell signaling controls key aspects of development. In plants, cells communicate through direct transfer of transcription factors between cells. It is thought that most, if not all, mobile transcription factors move via plasmodesmata, membrane-lined channels that connect nearly all cells in the plant. However, the mechanisms by which these proteins access the plasmodesmata are not known. Using four independent assays, we examined the movement of the SHORT-ROOT (SHR) transcription factor under conditions that affect microtubule stability, organization or dynamics. We found that intact microtubules are required for cell-to-cell trafficking of SHR. Either chemical or genetic disruption of microtubules results in a significant reduction in SHR transport. Interestingly, inhibition of microtubules also results in mis-localization of the SHR-INTERACTING EMBRYONIC LETHAL (SIEL) protein, which has been shown to bind directly to SHR and is required for SHR movement. These results show that microtubules facilitate cell-to-cell transport of an endogenous plant protein.
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Affiliation(s)
- Shuang Wu
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
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35
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McGarry RC, Kragler F. Phloem-mobile signals affecting flowers: applications for crop breeding. TRENDS IN PLANT SCIENCE 2013; 18:198-206. [PMID: 23395308 DOI: 10.1016/j.tplants.2013.01.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2012] [Revised: 01/06/2013] [Accepted: 01/07/2013] [Indexed: 05/23/2023]
Abstract
Transport of endogenous macromolecules within and between tissues serves as a signaling pathway to regulate numerous aspects of plant growth. The florigenic FT gene product moves via the phloem from leaves to apical tissues and induces the flowering program in meristems. Similarly, short interfering RNA (siRNA) signals produced in source or sink tissues move cell-to-cell and long distance via the phloem to apical tissues. Recent advances in identifying these mobile signals regulating flowering or the epigenetic status of targeted tissues can be applicable to crop-breeding programs. In this review, we address the identity of florigen, the mechanism of allocation, and how virus-induced flowering and grafting of transgenes producing siRNA signals affecting meiosis can produce transgene-free progenies useful for agriculture.
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Affiliation(s)
- Roisin C McGarry
- University of North Texas, Department of Biological Sciences, 1155 Union Circle 305220, Denton, TX 76203-5017, USA.
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36
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Plasmodesmata: intercellular tunnels facilitating transport of macromolecules in plants. Cell Tissue Res 2013; 352:49-58. [DOI: 10.1007/s00441-012-1550-1] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Accepted: 12/18/2012] [Indexed: 01/15/2023]
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37
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Cho SY, Cho WK, Choi HS, Kim KH. Cis-acting element (SL1) of Potato virus X controls viral movement by interacting with the NbMPB2Cb and viral proteins. Virology 2012; 427:166-76. [PMID: 22405626 DOI: 10.1016/j.virol.2012.02.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Revised: 01/09/2012] [Accepted: 02/04/2012] [Indexed: 01/21/2023]
Abstract
A number of candidate tobacco proteins that bind to cis-acting elements (SL1 RNAs) of Potato virus X (PVX) have been identified in previous studies. We further characterized TMV-MP30 binding protein 2C (MPB2C) homologous protein. We isolated NbMPB2Cb from Nicotiana benthamiana and confirmed the interaction of NbMPB2Cb with SL1 RNAs in vitro. The mRNA level of NbMPB2Cb was increased upon infection by PVX and Tobacco mosaic virus. The movement of PVX was reduced by overexpression of NbMPB2Cb and increased by silenced of NbMPB2Cb. In contrast, PVX RNA accumulation was not significantly altered in protoplasts. Protein-protein interaction assays showed that NbMPB2Cb interacts with PVX movement-associated proteins. PVX infection altered the subcellular localization of NbMPB2Cb from microtubules to endoplasmic reticulum. These data suggest that the NbMPB2Cb negatively affects PVX movement by interacting with SL1 RNAs and movement-associated proteins of PVX and by re-localizing in response to PVX infection.
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Affiliation(s)
- Sang-Yun Cho
- Department of Agricultural Biotechnology and Plant Genomics and Breeding Institute, College of Agriculture and Life Sciences, Seoul National University, Seoul 151-921, Republic of Korea
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38
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Lu KJ, Huang NC, Liu YS, Lu CA, Yu TS. Long-distance movement of Arabidopsis FLOWERING LOCUS T RNA participates in systemic floral regulation. RNA Biol 2012; 9:653-62. [PMID: 22614833 DOI: 10.4161/rna.19965] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The finding of mRNA acting as a systemic information molecule is one of the most exciting discoveries in recent plant biology. However, evidence demonstrating the functional significance of non-cell autonomous RNA remains limited. Recent analyses of Arabidopsis and rice revealed FLOWERING LOCUS T (FT) protein as a systemic florigenic signal. However, whether the FT RNA also participates in systemic floral regulation remains controversial. By using Arabidopsis cleft-grafting experiments, we showed that the RNA of Arabidopsis FT undergoes long-distance movement from the stock to the scion apex in both FT transformants and non-transformants. In addition, the sequences of FT RNA are sufficient to target a cell-autonomous RNA for long-distance movement. Therefore, FT RNA is a bona fide non-cell autonomous RNA. To examine the systemic action of FT RNA, we uncoupled the movement of FT RNA from protein by fusing FT with RED FLUORESCENT PROTEIN (RFP). When RFP-FT protein was retained in companion cells, the detection of RFP-FT RNA correlates with floral promotion in the scion. Further depletion of the translocated RFP-FT RNA by RNAi or artificial miRNA against FT delayed the floral promotion, indicating that the translocated FT RNA acts as a part of the systemic floral signaling. Our results indicate that both FT RNA and protein move long distance and act redundantly to integrate the photoperiodic signals.
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Affiliation(s)
- Kuan-Ju Lu
- Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, National Chung-Hsing University and Academia Sinica, Taipei, Taiwan
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39
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Fichtenbauer D, Xu XM, Jackson D, Kragler F. The chaperonin CCT8 facilitates spread of tobamovirus infection. PLANT SIGNALING & BEHAVIOR 2012; 7:318-21. [PMID: 22476462 PMCID: PMC3443910 DOI: 10.4161/psb.19152] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The homeodomain transcription factor KNOTTED1 (KN1) functions in shoot meristem maintenance and is thought to move from cell to cell in a similar fashion as viral movement proteins. Both types of transported proteins bind to RNA, and associate with intercellular bridges formed by plasmodesmata. In a mutant screen for KN1 transport deficiency, a component of a type II chaperonin complex, CCT8, was identified, and found to interact with non-cell-autonomous proteins. The cct8 mutants are characterized by limited functionality of non-cell-autonomous proteins after their movement, and a phenotype resembling lack of homeodomain protein activity. Evidence suggests that CCT8 functions in post-translocational refolding of transported proteins. Here we show that spread of tobamovirus infection is reduced in a cct8 mutant. This suggests that similar to KN1, viral movement proteins are unfolded and refolded during transport to gain functionality in the receiving cells.
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Affiliation(s)
- Daniela Fichtenbauer
- Department of Biochemistry and Cell Biology; Center for Molecular Biology; University of Vienna; Vienna, Austria
- Max Planck Institute of Molecular Plant Physiology; Golm, Germany
| | | | - Dave Jackson
- Cold Spring Harbor Laboratories; Cold Spring Harbor, NY USA
| | - Friedrich Kragler
- Department of Biochemistry and Cell Biology; Center for Molecular Biology; University of Vienna; Vienna, Austria
- Max Planck Institute of Molecular Plant Physiology; Golm, Germany
- Correspondence to: Friedrich Kragler;
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40
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Peña EJ, Heinlein M. RNA transport during TMV cell-to-cell movement. FRONTIERS IN PLANT SCIENCE 2012; 3:193. [PMID: 22973280 PMCID: PMC3428586 DOI: 10.3389/fpls.2012.00193] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Accepted: 08/06/2012] [Indexed: 05/08/2023]
Abstract
Studies during the last 25 years have provided increasing evidence for the ability of plants to support the cell-to-cell and systemic transport of RNA molecules and that this process plays a role in plant development and in the systemic orchestration of cellular responses against pathogens and other environmental challenges. Since RNA viruses exploit the cellular RNA transport machineries for spreading their genomes between cells they represent convenient models to investigate the underlying mechanisms. In this regard, the intercellular spread of Tobacco mosaic virus (TMV) has been studied for many years. The RNA of TMV moves cell-to-cell in a non-encapsidated form in a process depending on virus-encoded movement protein (MP). Here, we discuss the current state of the art in studies using TMV and its MP as a model for RNA transport. While the ability of plants to transport viral and cellular RNA molecules is consistent with RNA transport phenomena in other systems, further studies are needed to increase our ability to visualize viral RNA (vRNA) in vivo and to distinguish RNA-transport related processes from those involved in antiviral defense.
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Affiliation(s)
- Eduardo J. Peña
- Institut de Biologie Moléculaire des Plantes du Centre National de la Recherche Scientifique, Université de StrasbourgStrasbourg, France
| | - Manfred Heinlein
- Institut de Biologie Moléculaire des Plantes du Centre National de la Recherche Scientifique, Université de StrasbourgStrasbourg, France
- Department of Plant Physiology, University of BaselBasel, Switzerland
- *Correspondence: Manfred Heinlein, Institut de Biologie Moléculaire des Plantes du Centre National de la Recherche Scientifique, UPR 2357, Université de Strasbourg, 12, Rue du Général Zimmer, 67084 Strasbourg cedex, France. e-mail:
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41
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Xu XM, Wang J, Xuan Z, Goldshmidt A, Borrill PGM, Hariharan N, Kim JY, Jackson D. Chaperonins facilitate KNOTTED1 cell-to-cell trafficking and stem cell function. Science 2011; 333:1141-4. [PMID: 21868675 DOI: 10.1126/science.1205727] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Cell-to-cell communication in plants includes the selective trafficking of transcription factors and other signals through plasmodesmata. The KNOTTED1 (KN1) homeobox (KNOX) family transcription factors, which use this pathway, are essential for stem cell establishment and/or maintenance. Here we show that KN1 trafficking requires the chaperonin complex, which belongs to a group of cytosolic chaperones that fold specific substrate proteins. Genetic and physical interaction data show a functional relevance for chaperonins in KNOX family-dependent stem cell maintenance. Furthermore, tissue-specific complementation assays indicate a mechanistic basis for chaperonin function during the posttranslocational refolding process. Our study shows that chaperonins are essential for the cell-to-cell trafficking of a subset of mobile transcription factors and demonstrates the importance of chaperonin-dependent protein trafficking for plant stem cell function.
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Niehl A, Heinlein M. Cellular pathways for viral transport through plasmodesmata. PROTOPLASMA 2011; 248:75-99. [PMID: 21125301 DOI: 10.1007/s00709-010-0246-1] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2010] [Accepted: 11/16/2010] [Indexed: 05/03/2023]
Abstract
Plant viruses use plasmodesmata (PD) to spread infection between cells and systemically. Dependent on viral species, movement through PD can occur in virion or non-virion form, and requires different mechanisms for targeting and modification of the pore. These mechanisms are supported by viral movement proteins and by other virus-encoded factors that interact among themselves and with plant cellular components to facilitate virus movement in a coordinated and regulated fashion.
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Affiliation(s)
- Annette Niehl
- Institut de Biologie Moléculaire des Plantes du CNRS, Université de Strasbourg, 12 rue du Général Zimmer, 67084, Strasbourg, France
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Xu XM, Jackson D. Lights at the end of the tunnel: new views of plasmodesmal structure and function. CURRENT OPINION IN PLANT BIOLOGY 2010; 13:684-92. [PMID: 20934901 DOI: 10.1016/j.pbi.2010.09.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Revised: 08/16/2010] [Accepted: 09/07/2010] [Indexed: 05/06/2023]
Abstract
Plasmodesmata (PDs), tiny channels connecting neighboring plant cells, play big roles in the transport of metabolites, viral movement, cell fate specification and development. Many recent studies are opening our eyes to the composition and formation of PDs, as well as the function and regulation of trafficking through them. Both proteomic and genetic approaches have revealed the central importance of callose in modulating PD connectivity. Moreover, many new developmental regulators, including transcription factors as well as small RNAs (sRNAs), have been found to be mobile and essential for specifying cell fate and tissue patterning.
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Hay A, Tsiantis M. KNOX genes: versatile regulators of plant development and diversity. Development 2010; 137:3153-65. [PMID: 20823061 DOI: 10.1242/dev.030049] [Citation(s) in RCA: 357] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Knotted1-like homeobox (KNOX) proteins are homeodomain transcription factors that maintain an important pluripotent cell population called the shoot apical meristem, which generates the entire above-ground body of vascular plants. KNOX proteins regulate target genes that control hormone homeostasis in the meristem and interact with another subclass of homeodomain proteins called the BELL family. Studies in novel genetic systems, both at the base of the land plant phylogeny and in flowering plants, have uncovered novel roles for KNOX proteins in sculpting plant form and its diversity. Here, we discuss how KNOX proteins influence plant growth and development in a versatile context-dependent manner.
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Affiliation(s)
- Angela Hay
- Plant Sciences Department, University of Oxford, Oxford, UK.
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Koch J, Pranjic K, Huber A, Ellinger A, Hartig A, Kragler F, Brocard C. PEX11 family members are membrane elongation factors that coordinate peroxisome proliferation and maintenance. J Cell Sci 2010; 123:3389-400. [PMID: 20826455 DOI: 10.1242/jcs.064907] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Dynamic changes of membrane structure are intrinsic to organelle morphogenesis and homeostasis. Ectopic expression of proteins of the PEX11 family from yeast, plant or human lead to the formation of juxtaposed elongated peroxisomes (JEPs),which is evocative of an evolutionary conserved function of these proteins in membrane tubulation. Microscopic examinations reveal that JEPs are composed of independent elongated peroxisomes with heterogeneous distribution of matrix proteins. We established the homo- and heterodimerization properties of the human PEX11 proteins and their interaction with the fission factor hFis1, which is known to recruit the GTPase DRP1 to the peroxisomal membrane. We show that excess of hFis1 but not of DRP1 is sufficient to fragment JEPs into normal round-shaped organelles, and illustrate the requirement of microtubules for JEP formation. Our results demonstrate that PEX11-induced JEPs represent intermediates in the process of peroxisome membrane proliferation and that hFis1 is the limiting factor for progression. Hence, we propose a model for a conserved role of PEX11 proteins in peroxisome maintenance through peroxisome polarization, membrane elongation and segregation.
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Affiliation(s)
- Johannes Koch
- Max F. Perutz Laboratories, Center of Molecular Biology, University of Vienna, Department of Biochemistry and Cell Biology, Dr Bohr-Gasse 9, 1030, Vienna, Austria
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Abstract
Plant development depends on the activity of a group of dividing cells called the meristem. Extensive genetic analyses have identified the major regulators of the shoot apical meristem (SAM), which control the development of all aerial organs. Among them, the three-amino-acid-loop-extension (TALE) class of homeoproteins has been shown to control meristem formation and/or maintenance, organ morphogenesis, organ position, and several aspects of the reproductive phase. This family contains the KNOTTED-like homeodomain (KNOX) and BEL1-like Homeodomain (BELL) members, which function as heterodimers. In this review, we have reported the functions of the TALE members throughout the Arabidopsis life cycle. Genetic analyses revealed a complex network, as TALE members exhibit both overlapping and antagonistic activities. The characterization of a new KNOX member (KNATM), which lacks a homeodomain and interacts with other members to modulate their activities, adds another layer of complexity to this network. While the mode of action of these transcription factors is still largely unknown, they have been implicated in the regulation of several hormonal pathways, providing a link between gene regulatory networks and signaling in the SAM.
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Affiliation(s)
- Olivier Hamant
- Laboratoire de reproduction et développement des plantes, Institut National de la Recherche Agronomique, CNRS/ENS, université de Lyon, 46 Allée d'Italie, Lyon cedex 07, France
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Lucas WJ, Ham BK, Kim JY. Plasmodesmata - bridging the gap between neighboring plant cells. Trends Cell Biol 2009; 19:495-503. [PMID: 19748270 DOI: 10.1016/j.tcb.2009.07.003] [Citation(s) in RCA: 167] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2009] [Revised: 07/20/2009] [Accepted: 07/20/2009] [Indexed: 12/15/2022]
Abstract
Land plants have developed highly sophisticated intercellular channels called plasmodesmata (PD) that mediate the cell-to-cell trafficking of signaling molecules, including non-cell autonomous proteins (NCAPs) and RNAs. Until recently, the biological significance of this position-dependent intercellular signaling system was underestimated, as only a limited number of endogenous NCAPs had been discovered. However, identification of an ever-increasing population of NCAPs suggests that the PD communication pathway is involved in diverse biological processes, ranging from development to pathogen defense. The identification of components involved in plasmodesmal structure and associated signaling molecules is now yielding novel insights into the evolution and function of PD in mediating the trafficking of non-cell-autonomous information macromolecules. Important future challenges are to build a detailed model for the plasmodesmal supramolecular complex and to further elucidate the molecular and cellular aspects of this novel plant cell-to-cell communication pathway.
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Affiliation(s)
- William J Lucas
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA 95616, USA.
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Ruggenthaler P, Fichtenbauer D, Krasensky J, Jonak C, Waigmann E. Microtubule-associated protein AtMPB2C plays a role in organization of cortical microtubules, stomata patterning, and tobamovirus infectivity. PLANT PHYSIOLOGY 2009; 149:1354-65. [PMID: 19074626 PMCID: PMC2649411 DOI: 10.1104/pp.108.130450] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2008] [Accepted: 11/25/2008] [Indexed: 05/20/2023]
Abstract
AtMPB2C is the Arabidopsis (Arabidopsis thaliana) homolog of MPB2C, a microtubule-associated host factor of tobacco mosaic virus movement protein that was been previously identified in Nicotiana tabacum. To analyze the endogenous function of AtMPB2C and its role in viral infections, transgenic Arabidopsis plant lines stably overexpressing green fluorescent protein (GFP)-AtMPB2C were established. The GFP-AtMPB2C fusion protein was detectable in various cell types and organs and localized at microtubules in a punctuate pattern or in filaments. To determine whether overexpression impacted on the cortical microtubular cytoskeleton, GFP-AtMPB2C-overexpressing plants were compared to known microtubular marker lines. In rapidly elongated cell types such as vein cells and root cells, GFP-AtMPB2C overexpression caused highly unordered assemblies of cortical microtubules, a disturbed, snake-like microtubular shape, and star-like crossing points of microtubules. Phenotypically, GFP-AtMPB2C transgenic plants showed retarded growth but were viable and fertile. Seedlings of GFP-AtMPB2C transgenic plants were characterized by clockwise twisted leaves, clustered stomata, and enhanced drought tolerance. GFP-AtMPB2C-overexpressing plants showed increased resistance against oilseed rape mosaic virus, a close relative of tobacco mosaic virus, but not against cucumber mosaic virus when compared to Arabidopsis wild-type plants. These results suggest that AtMPB2C is involved in the alignment of cortical microtubules, the patterning of stomata, and restricting tobamoviral infections.
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Affiliation(s)
- Pia Ruggenthaler
- Department of Medical Biochemistry, Medical University of Vienna, 1030 Vienna, Austria
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Maule AJ. Plasmodesmata: structure, function and biogenesis. CURRENT OPINION IN PLANT BIOLOGY 2008; 11:680-6. [PMID: 18824402 DOI: 10.1016/j.pbi.2008.08.002] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2008] [Revised: 08/01/2008] [Accepted: 08/12/2008] [Indexed: 05/07/2023]
Abstract
Plasmodesmata remain one of the outstanding mysteries in plant biology. In providing conduits for the exchange of small and large, informational molecules they are central to the growth, development and defence of all higher plants. In the past few years, strategies have been devised for the molecular dissection of plasmodesmal composition and function, and we are beginning to see how these enigmatic structures will become to be understood.
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Affiliation(s)
- Andrew J Maule
- John Innes Centre, Norwich Research Park, Colney, Norwich NR4 7UH, UK.
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Bolduc N, Hake S, Jackson D. Dual functions of the KNOTTED1 homeodomain: sequence-specific DNA binding and regulation of cell-to-cell transport. Sci Signal 2008; 1:pe28. [PMID: 18544748 DOI: 10.1126/scisignal.123pe28] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Homeodomain proteins are well-characterized developmental regulators that control expression of target genes through sequence-specific DNA binding. The homeodomain forms a trihelical structure, with the third helix conferring specific interactions with the DNA major groove. A specific class of plant homeodomain proteins, called KNOX [KNOTTED1 (KN1)-like homeobox], also has the ability to signal between cells by directly trafficking through intercellular channels called plasmodesmata. Trafficking is mediated by a signal that is also contained within the homeodomain. Movement protein binding protein 2C was identified as a protein that interacts with the KN1 homeodomain and regulates the cell-to-cell trafficking of KN1 by sequestering the protein on microtubules. Therefore, KN1 has multiple potential cellular addresses, each of which is conferred by its homeodomain.
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Affiliation(s)
- Nathalie Bolduc
- Plant Gene Expression Center, 800 Buchanan Street, Albany, CA 94710, USA
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