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Uyehara AN, Rasmussen CG. Redundant mechanisms in division plane positioning. Eur J Cell Biol 2023; 102:151308. [PMID: 36921356 DOI: 10.1016/j.ejcb.2023.151308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 03/05/2023] [Accepted: 03/11/2023] [Indexed: 03/18/2023] Open
Abstract
Redundancies in plant cell division contribute to the maintenance of proper division plane orientation. Here we highlight three types of redundancy: 1) Temporal redundancy, or correction of earlier defects that results in proper final positioning, 2) Genetic redundancy, or functional compensation by homologous genes, and 3) Synthetic redundancy, or redundancy within or between pathways that contribute to proper division plane orientation. Understanding the types of redundant mechanisms involved provides insight into current models of division plane orientation and opens up new avenues for exploration.
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Affiliation(s)
- Aimee N Uyehara
- Department of Botany and Plant Sciences, Center for Plant Cell Biology, University of California, Riverside, USA
| | - Carolyn G Rasmussen
- Department of Botany and Plant Sciences, Center for Plant Cell Biology, University of California, Riverside, USA.
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Máthé C, Freytag C, Kelemen A, M-Hamvas M, Garda T. "B" Regulatory Subunits of PP2A: Their Roles in Plant Development and Stress Reactions. Int J Mol Sci 2023; 24:ijms24065147. [PMID: 36982222 PMCID: PMC10049431 DOI: 10.3390/ijms24065147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 03/03/2023] [Accepted: 03/05/2023] [Indexed: 03/30/2023] Open
Abstract
Protein phosphatase PP2A is an enzyme complex consisting of C (catalytic), A (scaffold) and B (regulatory) subunits. B subunits are a large family of proteins that regulate activity, substrate specificity and subcellular localization of the holoenzyme. Knowledge on the molecular functions of PP2A in plants is less than for protein kinases, but it is rapidly increasing. B subunits are responsible for the large diversity of PP2A functioning. This paper intends to give a survey on their multiple regulatory mechanisms. Firstly, we give a short description on our current knowledge in terms of "B"-mediated regulation of metabolic pathways. Next, we present their subcellular localizations, which extend from the nucleus to the cytosol and membrane compartments. The next sections show how B subunits regulate cellular processes from mitotic division to signal transduction pathways, including hormone signaling, and then the emerging evidence for their regulatory (mostly modulatory) roles in both abiotic and biotic stress responses in plants. Knowledge on these issues should be increased in the near future, since it contributes to a better understanding of how plant cells work, it may have agricultural applications, and it may have new insights into how vascular plants including crops face diverse environmental challenges.
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Affiliation(s)
- Csaba Máthé
- Department of Botany, Faculty of Science and Technology, University of Debrecen, H-4032 Debrecen, Hungary
| | - Csongor Freytag
- Department of Botany, Faculty of Science and Technology, University of Debrecen, H-4032 Debrecen, Hungary
| | - Adrienn Kelemen
- Department of Botany, Faculty of Science and Technology, University of Debrecen, H-4032 Debrecen, Hungary
| | - Márta M-Hamvas
- Department of Botany, Faculty of Science and Technology, University of Debrecen, H-4032 Debrecen, Hungary
| | - Tamás Garda
- Department of Botany, Faculty of Science and Technology, University of Debrecen, H-4032 Debrecen, Hungary
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Vavrdová T, ˇSamaj J, Komis G. Phosphorylation of Plant Microtubule-Associated Proteins During Cell Division. FRONTIERS IN PLANT SCIENCE 2019; 10:238. [PMID: 30915087 PMCID: PMC6421500 DOI: 10.3389/fpls.2019.00238] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 02/12/2019] [Indexed: 05/20/2023]
Abstract
Progression of mitosis and cytokinesis depends on the reorganization of cytoskeleton, with microtubules driving the segregation of chromosomes and their partitioning to two daughter cells. In dividing plant cells, microtubules undergo global reorganization throughout mitosis and cytokinesis, and with the aid of various microtubule-associated proteins (MAPs), they form unique systems such as the preprophase band (PPB), the acentrosomal mitotic spindle, and the phragmoplast. Such proteins include nucleators of de novo microtubule formation, plus end binding proteins involved in the regulation of microtubule dynamics, crosslinking proteins underlying microtubule bundle formation and members of the kinesin superfamily with microtubule-dependent motor activities. The coordinated function of such proteins not only drives the continuous remodeling of microtubules during mitosis and cytokinesis but also assists the positioning of the PPB, the mitotic spindle, and the phragmoplast, affecting tissue patterning by controlling cell division plane (CDP) orientation. The affinity and the function of such proteins is variably regulated by reversible phosphorylation of serine and threonine residues within the microtubule binding domain through a number of protein kinases and phosphatases which are differentially involved throughout cell division. The purpose of the present review is to provide an overview of the function of protein kinases and protein phosphatases involved in cell division regulation and to identify cytoskeletal substrates relevant to the progression of mitosis and cytokinesis and the regulation of CDP orientation.
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Smet W, De Rybel B. Genetic and hormonal control of vascular tissue proliferation. CURRENT OPINION IN PLANT BIOLOGY 2016; 29:50-6. [PMID: 26724501 DOI: 10.1016/j.pbi.2015.11.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 11/04/2015] [Accepted: 11/05/2015] [Indexed: 05/28/2023]
Abstract
The plant vascular system develops from a handful of provascular initial cells in the early embryo into a whole range of different cell types in the mature plant. In order to account for such proliferation and to generate this kind of diversity, vascular tissue development relies on a large number of highly oriented cell divisions. Different hormonal and genetic pathways have been implicated in this process and several of these have been recently interconnected. Nevertheless, how such networks control the actual division plane orientation and how they interact with the generic cell cycle machinery to coordinate these divisions remains a major unanswered question.
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Affiliation(s)
- Wouter Smet
- Laboratory of Biochemistry, Wageningen University, Dreijenlaan 3, 6703HA Wageningen, The Netherlands
| | - Bert De Rybel
- Laboratory of Biochemistry, Wageningen University, Dreijenlaan 3, 6703HA Wageningen, The Netherlands; Department of Plant Systems Biology, VIB, Technologiepark 927, B-9052 Ghent, Belgium; Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 927, B-9052 Ghent, Belgium.
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Rasmussen CG, Wright AJ, Müller S. The role of the cytoskeleton and associated proteins in determination of the plant cell division plane. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 75:258-69. [PMID: 23496276 DOI: 10.1111/tpj.12177] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Revised: 02/26/2013] [Accepted: 03/12/2013] [Indexed: 05/08/2023]
Abstract
In plants, as in all eukaryotic organisms, microtubule- and actin-filament based structures play fundamental roles during cell division. In addition to the mitotic spindle, plant cells have evolved a unique cytoskeletal structure that designates a specific division plane before the onset of mitosis via formation of a cortical band of microtubules and actin filaments called the preprophase band. During cytokinesis, a second plant-specific microtubule and actin filament structure called the phragmoplast directs vesicles to create the new cell wall. In response to intrinsic and extrinsic cues, many plant cells form a preprophase band in G2 , then the preprophase band recruits specific proteins to populate the cortical division site prior to disassembly of the preprophase band in prometaphase. These proteins are thought to act as a spatial reminder that actively guides the phragmoplast towards the cortical division site during cytokinesis. A number of proteins involved in determination and maintenance of the plane of cell division have been identified. Our current understanding of the molecular interactions of these proteins and their regulation of microtubules is incomplete, but advanced imaging techniques and computer simulations have validated some early concepts of division site determination.
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Affiliation(s)
- Carolyn G Rasmussen
- Department of Molecular Biology, University of Wyoming, 1000 E. University Avenue, Laramie, WY, USA.
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The Preprophase Band and Division Site Determination in Land Plants. THE PLANT CYTOSKELETON 2011. [DOI: 10.1007/978-1-4419-0987-9_7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Rasmussen CG, Humphries JA, Smith LG. Determination of symmetric and asymmetric division planes in plant cells. ANNUAL REVIEW OF PLANT BIOLOGY 2011; 62:387-409. [PMID: 21391814 DOI: 10.1146/annurev-arplant-042110-103802] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The cellular organization of plant tissues is determined by patterns of cell division and growth coupled with cellular differentiation. Cells proliferate mainly via symmetric division, whereas asymmetric divisions are associated with initiation of new developmental patterns and cell types. Division planes in both symmetrically and asymmetrically dividing cells are established through the action of a cortical preprophase band (PPB) of cytoskeletal filaments, which is disassembled upon transition to metaphase, leaving behind a cortical division site (CDS) to which the cytokinetic phragmoplast is later guided to position the cell plate. Recent progress has been made in understanding PPB formation and function as well as the nature and function of the CDS. In asymmetrically dividing cells, division plane establishment is governed by cell polarity. Recent work is beginning to shed light on polarization mechanisms in asymmetrically dividing cells, with receptor-like proteins and potential downstream effectors emerging as important players in this process.
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Affiliation(s)
- Carolyn G Rasmussen
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, California 92093, USA.
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Rasmussen CG, Sun B, Smith LG. Tangled localization at the cortical division site of plant cells occurs by several mechanisms. J Cell Sci 2010; 124:270-9. [PMID: 21172800 DOI: 10.1242/jcs.073676] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
TANGLED (TAN) is the founding member of a family of plant-specific proteins required for correct orientation of the division plane. Arabidopsis thaliana TAN is localized before prophase until the end of cytokinesis at the cortical division site (CDS), where it appears to help guide the cytokinetic apparatus towards the cortex. We show that TAN is actively recruited to the CDS by distinct mechanisms before and after preprophase band (PPB) disassembly. Colocalization with the PPB is mediated by one region of TAN, whereas another region mediates its recruitment to the CDS during cytokinesis. This second region binds directly to POK1, a kinesin that is required for TAN localization. Although this region of TAN is recruited to the CDS during cytokinesis without first colocalizing with the PPB, pharmacological evidence indicates that the PPB is nevertheless required for both early and late localization of TAN at the CDS. Finally, we show that phosphatase activity is required for maintenance of early but not late TAN localization at the CDS. We propose a new model in which TAN is actively recruited to the CDS by several mechanisms, indicating that the CDS is dynamically modified from prophase through to the completion of cytokinesis.
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Affiliation(s)
- Carolyn G Rasmussen
- University of California, San Diego, Section of Cell and Developmental Biology, 9500 Gilman Dr., La Jolla, CA 92093-0116, USA.
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Frey N, Klotz J, Nick P. A kinesin with calponin-homology domain is involved in premitotic nuclear migration. JOURNAL OF EXPERIMENTAL BOTANY 2010; 61:3423-37. [PMID: 20566563 PMCID: PMC2905203 DOI: 10.1093/jxb/erq164] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Revised: 05/15/2010] [Accepted: 05/18/2010] [Indexed: 05/17/2023]
Abstract
Interaction and cross-talk between microtubules and actin microfilaments are important for numerous processes during plant growth and development, including the control of cell elongation and tissue expansion, but little is known about the molecular components of this interaction. Plant kinesins with the calponin-homology domain (KCH) were recently identified and associated with a putative role in microtubule-microfilament cross-linking. The putative biological role of the rice KCH member OsKCH1 is addressed here using a combined approach with Tos17 kch1 knock-out mutants on the one hand, and a KCH1 overexpression line generated in tobacco BY-2 cells. It is shown that OsKCH1 is expressed in a development and tissue-specific manner in rice and antagonistic cell elongation and division phenotypes as a result of knock-down and overexpression are reported. Further, the dynamic repartitioning of OsKCH1 during the cell cycle is described and it is demonstrated that KCH overexpression delays nuclear positioning and mitosis in BY-2 cells. These findings are discussed with respect to a putative role of KCHs as linkers between actin filaments and microtubules during nuclear positioning.
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Affiliation(s)
- Nicole Frey
- Institute of Botany 1 and Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology (KIT), Kaiserstrasse 2, D-76131 Karlsruhe, Germany.
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Guo L, Ho CMK, Kong Z, Lee YRJ, Qian Q, Liu B. Evaluating the microtubule cytoskeleton and its interacting proteins in monocots by mining the rice genome. ANNALS OF BOTANY 2009; 103:387-402. [PMID: 19106179 PMCID: PMC2707338 DOI: 10.1093/aob/mcn248] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2008] [Revised: 10/20/2008] [Accepted: 11/17/2008] [Indexed: 05/20/2023]
Abstract
BACKGROUND Microtubules (MTs) are assembled by heterodimers of alpha- and beta-tubulins, which provide tracks for directional transport and frameworks for the spindle apparatus and the phragmoplast. MT nucleation and dynamics are regulated by components such as the gamma-tubulin complex which are conserved among eukaryotes, and other components which are unique to plants. Following remarkable progress made in the model plant Arabidopsis thaliana toward revealing key components regulating MT activities, the completed rice (Oryza sativa) genome has prompted a survey of the MT cytoskeleton in this important crop as a model for monocots. SCOPE The rice genome contains three alpha-tubulin genes, eight beta-tubulin genes and a single gamma-tubulin gene. A functional gamma-tubulin ring complex is expected to form in rice as genes encoding all components of the complex are present. Among proteins that interact with MTs, compared with A. thaliana, rice has more genes encoding some members such as the MAP65/Ase1p/PRC1 family, but fewer for the motor kinesins, the end-binding protein EB1 and the mitotic kinase Aurora. Although most known MT-interacting factors have apparent orthologues in rice, no orthologues of arabidopsis RIC1 and MAP18 have been identified in rice. Among all proteins surveyed here, only a few have had their functions characterized by genetic means in rice. Elucidating functions of proteins of the rice MT cytoskeleton, aided by recent technical advances made in this model monocot, will greatly advance our knowledge of how monocots employ their MTs to regulate their growth and form.
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Affiliation(s)
- Longbiao Guo
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou 310006, China
- Department of Plant Biology, University of California, Davis, CA 95616, USA
| | - Chin-Min Kimmy Ho
- Department of Plant Biology, University of California, Davis, CA 95616, USA
| | - Zhaosheng Kong
- Department of Plant Biology, University of California, Davis, CA 95616, USA
| | - Yuh-Ru Julie Lee
- Department of Plant Biology, University of California, Davis, CA 95616, USA
| | - Qian Qian
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou 310006, China
| | - Bo Liu
- Department of Plant Biology, University of California, Davis, CA 95616, USA
- For correspondence. E-mail:
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Wright AJ, Gallagher K, Smith LG. discordia1 and alternative discordia1 function redundantly at the cortical division site to promote preprophase band formation and orient division planes in maize. THE PLANT CELL 2009; 21:234-47. [PMID: 19168717 PMCID: PMC2648079 DOI: 10.1105/tpc.108.062810] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2008] [Revised: 12/15/2008] [Accepted: 01/06/2009] [Indexed: 05/18/2023]
Abstract
In plants, cell wall placement during cytokinesis is determined by the position of the preprophase band (PPB) and the subsequent expansion of the phragmoplast, which deposits the new cell wall, to the cortical division site delineated by the PPB. New cell walls are often incorrectly oriented during asymmetric cell divisions in the leaf epidermis of maize (Zea mays) discordia1 (dcd1) mutants, and this defect is associated with aberrant PPB formation in asymmetrically dividing cells. dcd1 was cloned and encodes a putative B'' regulatory subunit of the PP2A phosphatase complex highly similar to Arabidopsis thaliana FASS/TONNEAU2, which is required for PPB formation. We also identified alternative discordia1 (add1), a second gene in maize nearly identical to dcd1. While loss of add1 function does not produce a noticeable phenotype, knock down of both genes in add1(RNAi) dcd1(RNAi) plants prevents PPB formation and causes misorientation of symmetric and asymmetric cell divisions. Immunolocalization studies with an antibody that recognizes both DCD1 and ADD1 showed that these proteins colocalize with PPBs and remain at the cortical division site through metaphase. Our results indicate that DCD1 and ADD1 function in PPB formation, that this function is more critical in asymmetrically dividing cells than in symmetrically dividing cells, and that DCD1/ADD1 may have other roles in addition to promoting PPB formation at the cortical division site.
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Affiliation(s)
- Amanda J Wright
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, California 92093-0116, USA.
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Azimzadeh J, Nacry P, Christodoulidou A, Drevensek S, Camilleri C, Amiour N, Parcy F, Pastuglia M, Bouchez D. Arabidopsis TONNEAU1 proteins are essential for preprophase band formation and interact with centrin. THE PLANT CELL 2008; 20:2146-59. [PMID: 18757558 PMCID: PMC2553619 DOI: 10.1105/tpc.107.056812] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Plant cells have specific microtubule structures involved in cell division and elongation. The tonneau1 (ton1) mutant of Arabidopsis thaliana displays drastic defects in morphogenesis, positioning of division planes, and cellular organization. These are primarily caused by dysfunction of the cortical cytoskeleton and absence of the preprophase band of microtubules. Characterization of the ton1 insertional mutant reveals complex chromosomal rearrangements leading to simultaneous disruption of two highly similar genes in tandem, TON1a and TON1b. TON1 proteins are conserved in land plants and share sequence motifs with human centrosomal proteins. The TON1 protein associates with soluble and microsomal fractions of Arabidopsis cells, and a green fluorescent protein-TON1 fusion labels cortical cytoskeletal structures, including the preprophase band and the interphase cortical array. A yeast two-hybrid screen identified Arabidopsis centrin as a potential TON1 partner. This interaction was confirmed both in vitro and in plant cells. The similarity of TON1 with centrosomal proteins and its interaction with centrin, another key component of microtubule organizing centers, suggests that functions involved in the organization of microtubule arrays by the centrosome were conserved across the evolutionary divergence between plants and animals.
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Affiliation(s)
- Juliette Azimzadeh
- Institut Jean-Pierre Bourgin, Station de Génétique et d'Amélioration des Plantes UR254, Institut National de la Recherche Agronomique, Centre de Versailles, F-78000 Versailles, France
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Van Damme D, Geelen D. Demarcation of the cortical division zone in dividing plant cells. Cell Biol Int 2007; 32:178-87. [PMID: 18083049 DOI: 10.1016/j.cellbi.2007.10.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2007] [Revised: 07/06/2007] [Accepted: 10/04/2007] [Indexed: 10/22/2022]
Abstract
Somatic cytokinesis in higher plants involves, besides the actual construction of a new cell wall, also the determination of a division zone. Several proteins have been shown to play a part in the mechanism that somatic plant cells use to control the positioning of the new cell wall. Plant cells determine the division zone at an early stage of cell division and use a transient microtubular structure, the preprophase band (PPB), during this process. The PPB is formed at the division zone, leaving behind a mark that during cytokinesis is utilized by the phragmoplast to guide the expanding cell plate toward the correct cortical insertion site. This review discusses old and new observations with regard to mechanisms implicated in the orientation of cell division and determination of a cortical division zone.
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Affiliation(s)
- Daniel Van Damme
- Department of Plant Systems Biology, Flanders Institute for Biotechnology, Ghen University, B-9052 Ghent, Belgium
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Griffith ME, Mayer U, Capron A, Ngo QA, Surendrarao A, McClinton R, Jürgens G, Sundaresan V. The TORMOZ gene encodes a nucleolar protein required for regulated division planes and embryo development in Arabidopsis. THE PLANT CELL 2007; 19:2246-63. [PMID: 17616738 PMCID: PMC1955705 DOI: 10.1105/tpc.106.042697] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Embryogenesis in Arabidopsis thaliana is marked by a predictable sequence of oriented cell divisions, which precede cell fate determination. We show that mutation of the TORMOZ (TOZ) gene yields embryos with aberrant cell division planes and arrested embryos that appear not to have established normal patterning. The defects in toz mutants differ from previously described mutations that affect embryonic cell division patterns. Longitudinal division planes of the proembryo are frequently replaced by transverse divisions and less frequently by oblique divisions, while divisions of the suspensor cells, which divide only transversely, appear generally unaffected. Expression patterns of selected embryo patterning genes are altered in the mutant embryos, implying that the positional cues required for their proper expression are perturbed by the misoriented divisions. The TOZ gene encodes a nucleolar protein containing WD repeats. Putative TOZ orthologs exist in other eukaryotes including Saccharomyces cerevisiae, where the protein is predicted to function in 18S rRNA biogenesis. We find that disruption of the Sp TOZ gene results in cell division defects in Schizosaccharomyces pombe. Previous studies in yeast and animal cells have identified nucleolar proteins that regulate the exit from M phase and cytokinesis, including factors involved in pre-rRNA processing. Our study suggests that in plant cells, nucleolar functions might interact with the processes of regulated cell divisions and influence the selection of longitudinal division planes during embryogenesis.
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Affiliation(s)
- Megan E Griffith
- Institute of Molecular and Cell Biology, Singapore 138673, Republic of Singapore
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Bisgrove SR, Kropf DL. Asymmetric Cell Divisions: Zygotes of Fucoid Algae as a Model System. PLANT CELL MONOGRAPHS 2007. [DOI: 10.1007/7089_2007_134] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Ehrhardt DW, Shaw SL. Microtubule dynamics and organization in the plant cortical array. ANNUAL REVIEW OF PLANT BIOLOGY 2006; 57:859-75. [PMID: 16669785 DOI: 10.1146/annurev.arplant.57.032905.105329] [Citation(s) in RCA: 144] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Live-cell studies have brought fresh insight into the organizational activities of the plant cortical array. Plant interphase arrays organize in the absence of a discrete microtubule organizing center, having plus and minus ends distributed throughout the cell cortex. Microtubule nucleation occurs at the cell cortex, frequently followed by minus-end detachment from origin sites. Microtubules associate tightly with the cell cortex, resisting lateral and axial translocation. Slow, intermitant loss of dimers from minus ends, coupled with growth-biased dynamic instability at the plus ends, results in the migration of cortically attached microtubules across the cell via polymer treadmilling. Microtubule-microtubule interactions, a direct consequence of treadmilling, result in polymer reorientation and creation of polymer bundles. The combined properties of microtubule dynamics and interactions among polymers constitute a system with predicted properties of self-organization.
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Affiliation(s)
- David W Ehrhardt
- Department of Plant Biology, Carnegie Institution, Stanford, California 94020, USA.
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Abstract
Many of the patterning mechanisms in plants were discovered while studying postembryonic processes and resemble mechanisms operating during animal development. The emergent role of the plant hormone auxin, however, seems to represent a plant-specific solution to multicellular patterning. This review summarizes our knowledge on how diverse mechanisms that were first dissected at the postembryonic level are now beginning to provide an understanding of plant embryogenesis.
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Affiliation(s)
- Viola Willemsen
- Department of Molecular Genetics, Utrecht University, 3584 CH Utrecht, The Netherlands.
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Dynamic Behavior of Microtubules and Vacuoles at M/G1 Interface Observed in Living Tobacco BY-2 Cells. TOBACCO BY-2 CELLS 2004. [DOI: 10.1007/978-3-662-10572-6_7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Himmelspach R, Williamson RE, Wasteneys GO. Cellulose microfibril alignment recovers from DCB-induced disruption despite microtubule disorganization. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2003; 36:565-75. [PMID: 14617086 DOI: 10.1046/j.1365-313x.2003.01906.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Cellulose microfibril deposition patterns define the direction of plant cell expansion. To better understand how microfibril alignment is controlled, we examined microfibril orientation during cortical microtubule disruption using the temperature-sensitive mutant of Arabidopsis thaliana, mor1-1. In a previous study, it was shown that at restrictive temperature for mor1-1, cortical microtubules lose transverse orientation and cells lose growth anisotropy without any change in the parallel arrangement of cellulose microfibrils. In this study, we investigated whether a pre-existing template of well-ordered microfibrils or the presence of well-organized cortical microtubules was essential for the cell to resume deposition of parallel microfibrils. We first transiently disrupted the parallel order of microfibrils in mor1-1 using a brief treatment with the cellulose synthesis inhibitor 2,6-dichlorobenzonitrile (DCB). We then analysed the alignment of recently deposited cellulose microfibrils (by field emission scanning electron microscopy) as cellulose synthesis recovered and microtubules remained disrupted at the mor1-1 mutant's non-permissive culture temperature. Despite the disordered cortical microtubules and an initially randomized wall texture, new cellulose microfibrils were deposited with parallel, transverse orientation. These results show that transverse cellulose microfibril deposition requires neither accurately transverse cortical microtubules nor a pre-existing template of well-ordered microfibrils. We also demonstrated that DCB treatments reduced the ability of cortical microtubules to form transverse arrays, supporting a role for cellulose microfibrils in influencing cortical microtubule organization.
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Affiliation(s)
- Regina Himmelspach
- Plant Cell Biology Group, Research School of Biological Sciences, The Australian National University, Canberra ACT 2601, Australia
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Dhonukshe P, Laxalt AM, Goedhart J, Gadella TWJ, Munnik T. Phospholipase d activation correlates with microtubule reorganization in living plant cells. THE PLANT CELL 2003; 15:2666-79. [PMID: 14508002 PMCID: PMC280570 DOI: 10.1105/tpc.014977] [Citation(s) in RCA: 163] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2003] [Accepted: 08/22/2003] [Indexed: 05/18/2023]
Abstract
A phospholipase D (PLD) was shown recently to decorate microtubules in plant cells. Therefore, we used tobacco BY-2 cells expressing the microtubule reporter GFP-MAP4 to test whether PLD activation affects the organization of plant microtubules. Within 30 min of adding n-butanol, a potent activator of PLD, cortical microtubules were released from the plasma membrane and partially depolymerized, as visualized with four-dimensional confocal imaging. The isomers sec- and tert-butanol, which did not activate PLD, did not affect microtubule organization. The effect of treatment on PLD activation was monitored by the in vivo formation of phosphatidylbutanol, a specific reporter of PLD activity. Tobacco cells also were treated with mastoparan, xylanase, NaCl, and hypoosmotic stress as reported activators of PLD. We confirmed the reports and found that all treatments induced microtubule reorganization and PLD activation within the same time frame. PLD still was activated in microtubule-stabilized (taxol) and microtubule-depolymerized (oryzalin) situations, suggesting that PLD activation triggers microtubular reorganization and not vice versa. Exogenously applied water-soluble synthetic phosphatidic acid did not affect the microtubular cytoskeleton. Cell cycle studies revealed that n-butanol influenced not just interphase cortical microtubules but also those in the preprophase band and phragmoplast, but not those in the spindle structure. Cell growth and division were inhibited in the presence of n-butanol, whereas sec- and tert-butanol had no such effects. Using these novel insights, we propose a model for the mechanism by which PLD activation triggers microtubule reorganization in plant cells.
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Affiliation(s)
- Pankaj Dhonukshe
- Section of Molecular Cytology, Swammerdam Institute for Life Sciences, University of Amsterdam, NL-1090 GB Amsterdam, The Netherlands
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22
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Dhonukshe P, Gadella TWJ. Alteration of microtubule dynamic instability during preprophase band formation revealed by yellow fluorescent protein-CLIP170 microtubule plus-end labeling. THE PLANT CELL 2003; 15:597-611. [PMID: 12615935 PMCID: PMC150016 DOI: 10.1105/tpc.008961] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2002] [Accepted: 01/01/2003] [Indexed: 05/17/2023]
Abstract
At the onset of mitosis, plant cells form a microtubular preprophase band that defines the plane of cell division, but the mechanism of its formation remains a mystery. Here, we describe the use of mammalian yellow fluorescent protein-tagged CLIP170 to visualize the dynamic plus ends of plant microtubules in transfected cowpea protoplasts and in stably transformed and dividing tobacco Bright Yellow 2 cells. Using plus-end labeling, we observed dynamic instability in different microtubular conformations in live plant cells. The interphase plant microtubules grow at 5 micro m/min, shrink at 20 micro m/min, and display catastrophe and rescue frequencies of 0.02 and 0.08 events/s, respectively, exhibiting faster turnover than their mammalian counterparts. Strikingly, during preprophase band formation, the growth rate and catastrophe frequency of plant microtubules double, whereas the shrinkage rate and rescue frequency remain unchanged, making microtubules shorter and more dynamic. Using these novel insights and four-dimensional time-lapse imaging data, we propose a model that can explain the mechanism by which changes in microtubule dynamic instability drive the dramatic rearrangements of microtubules during preprophase band and spindle formation in plant cells.
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Affiliation(s)
- Pankaj Dhonukshe
- Section of Molecular Cytology, Swammerdam Institute for Life Sciences, University of Amsterdam, PO Box 94062, NL-1090 GB Amsterdam, The Netherlands
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Ilgenfritz H, Bouyer D, Schnittger A, Mathur J, Kirik V, Schwab B, Chua NH, Jürgens G, Hülskamp M. The Arabidopsis STICHEL gene is a regulator of trichome branch number and encodes a novel protein. PLANT PHYSIOLOGY 2003; 131:643-55. [PMID: 12586888 PMCID: PMC166840 DOI: 10.1104/pp.014209] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2002] [Revised: 10/25/2002] [Accepted: 11/14/2002] [Indexed: 05/19/2023]
Abstract
Here, we analyze the STICHEL (STI) gene, which plays an important role in the regulation of branch number of the unicellular trichomes in Arabidopsis. We have isolated the STI locus by positional cloning and confirmed the identity by sequencing seven independent sti alleles. The STI gene encodes a protein of 1,218 amino acid residues containing a domain with sequence similarity to the ATP-binding eubacterial DNA-polymerase III gamma-subunits. Because endoreduplication was found to be normal in sti mutants the molecular function of STI in cell morphogenesis is not linked to DNA replication and, therefore, postulated to represent a novel pathway. Northern-blot analysis shows that STI is expressed in all organs suggesting that STI function is not trichome specific. The analysis of sti alleles and transgenic lines overexpressing STI suggests that STI regulates branching in a dosage-dependent manner.
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Affiliation(s)
- Hilmar Ilgenfritz
- Zentrum für Molekularbiologie Pflanzen, Entwicklungsgenetik, Universität Tübingen, Auf der Morgenstelle 1, D-72076 Tübingen, Germany
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24
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Sørensen MB, Mayer U, Lukowitz W, Robert H, Chambrier P, Jürgens G, Somerville C, Lepiniec L, Berger F. Cellularisation in the endosperm of Arabidopsis thaliana is coupled to mitosis and shares multiple components with cytokinesis. Development 2002; 129:5567-76. [PMID: 12421698 DOI: 10.1242/dev.00152] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Distinct forms of cytokinesis characterise specific phases of development in plants. In Arabidopsis, as in many other species, the endosperm that nurtures the embryo in the seed initially develops as a syncytium. This syncytial phase ends with simultaneous partitioning of the multinucleate cytoplasm into individual cells, a process referred to as cellularisation. Our in vivo observations show that, as in cytokinesis, cellularisation of the Arabidopsis endosperm is coupled to nuclear division. A genetic analysis reveals that most Arabidopsis mutations affecting cytokinesis in the embryo also impair endosperm cellularisation. These results imply that cellularisation and cytokinesis share multiple components of the same basic machinery. We further report the identification of mutations in a novel gene, SPATZLE, that specifically interfere with cellularisation of the endosperm, but not with cytokinesis in the embryo. The analysis of this mutant might identify a specific checkpoint for the onset of cellularisation.
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Affiliation(s)
- Mikael Blom Sørensen
- Laboratoire de Reproduction et Développement des Plantes, UMR 5667, Ecole Normale Supérieure de Lyon, 46 Allée d'Italie, F-69364 Lyon, Cedex 07, France
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25
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Wiedemeier AMD, Judy-March JE, Hocart CH, Wasteneys GO, Williamson RE, Baskin TI. Mutant alleles of Arabidopsis RADIALLY SWOLLEN 4 and 7 reduce growth anisotropy without altering the transverse orientation of cortical microtubules or cellulose microfibrils. Development 2002; 129:4821-30. [PMID: 12361973 DOI: 10.1242/dev.129.20.4821] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The anisotropic growth of plant cells depends on cell walls having anisotropic mechanical properties, which are hypothesized to arise from aligned cellulose microfibrils. To test this hypothesis and to identify genes involved in controlling plant shape, we isolated mutants in Arabidopsis thaliana in which the degree of anisotropic expansion of the root is reduced. We report here the characterization of mutants at two new loci, RADIALLY SWOLLEN 4 (RSW4) and RSW7. The radial swelling phenotype is temperature sensitive, being moderate (rsw7) or negligible (rsw4) at the permissive temperature, 19°C, and pronounced at the restrictive temperature, 30°C. After transfer to 30°C, the primary root’s elongation rate decreases and diameter increases, with all tissues swelling radially. Swelling is accompanied by ectopic cell production but swelling is not reduced when the extra cell production is eliminated chemically. A double mutant was generated, whose roots swell constitutively and more than either parent. Based on analytical determination of acid-insoluble glucose, the amount of cellulose was normal in rsw4 and slightly elevated in rsw7. The orientation of cortical microtubules was examined with immunofluorescence in whole mounts and in semi-thin plastic sections, and the orientation of microfibrils was examined with field-emission scanning electron microscopy and quantitative polarized-light microscopy. In the swollen regions of both mutants, cortical microtubules and cellulose microfibrils are neither depleted nor disoriented. Thus, oriented microtubules and microfibrils themselves are insufficient to limit radial expansion; to build a wall with high mechanical anisotropy, additional factors are required, supplied in part by RSW4 and RSW7.
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26
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Abstract
Plant microtubule arrays differ fundamentally from their animal, fungal and protistan counterparts. These differences largely reflect the requirements of plant composite polymer cell walls and probably also relate to the acquisition of chloroplasts. Plant microtubules are usually dispersed and lack conspicuous organizing centres. The key to understanding this dispersed nature is the identification of proteins that interact with and regulate the spatial and dynamic properties of microtubules. Over the past decade, a number of these proteins have been uncovered, including numerous kinesin-related proteins and a 65 kDa class of structural microtubule-associated proteins that appear to be unique to plants. Mutational analysis has identified MOR1, a probable stabilizer of microtubules that is a homologue of the TOGp-XMAP215 class of high-molecular-weight microtubule-associated proteins, and a katanin p60 subunit homologue implicated in the severing of microtubules. The identification of these two proteins provides new insights into the mechanisms controlling microtubule assembly and dynamics, particularly in the dispersed cortical array found in highly polarized plant cells.
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Affiliation(s)
- Geoffrey O Wasteneys
- Plant Cell Biology Group, Research School of Biological Sciences, The Australian National University, GPO Box 475, Canberra ACT 2601, Australia.
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27
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Kim GT, Shoda K, Tsuge T, Cho KH, Uchimiya H, Yokoyama R, Nishitani K, Tsukaya H. The ANGUSTIFOLIA gene of Arabidopsis, a plant CtBP gene, regulates leaf-cell expansion, the arrangement of cortical microtubules in leaf cells and expression of a gene involved in cell-wall formation. EMBO J 2002; 21:1267-79. [PMID: 11889033 PMCID: PMC125914 DOI: 10.1093/emboj/21.6.1267] [Citation(s) in RCA: 158] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2001] [Revised: 12/03/2001] [Accepted: 12/20/2001] [Indexed: 11/14/2022] Open
Abstract
We previously showed that the ANGUSTIFOLIA (AN) gene regulates the width of leaves of Arabidopsis thaliana, by controlling the polar elongation of leaf cells. In the present study, we found that the abnormal arrangement of cortical microtubules (MTs) in an leaf cells appeared to account entirely for the abnormal shape of the cells. It suggested that the AN gene might regulate the polarity of cell growth by controlling the arrangement of cortical MTs. We cloned the AN gene using a map-based strategy and identified it as the first member of the CtBP family to be found in plants. Wild-type AN cDNA reversed the narrow-leaved phenotype and the abnormal arrangement of cortical MTs of the an-1 mutation. In the animal kingdom, CtBPs self-associate and act as co-repressors of transcription. The AN protein can also self-associate in the yeast two-hybrid system. Furthermore, microarray analysis suggested that the AN gene might regulate the expression of certain genes, e.g. the gene involved in formation of cell walls, MERI5. A discussion of the molecular mechanisms involved in the leaf shape regulation is presented based on our observations.
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Affiliation(s)
- Gyung-Tae Kim
- National Institute for Basic Biology/Center for Integrative Bioscience, 38 Nishigounaka, Myodaiji-cho, Okazaki 444-8585, Institute for Molecular and Cellular Biosciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai, 980-77 and Form and Function, PRESTO, Japan Science and Technology Corporation, 4-1-8 Honcho, Kawaguchi 332-0012 and School of Advanced Sciences, the Graduate University for Advanced Studies, Shonan Villege, Hayama, Kanagawa 240-0193, Japan Present address: Molecular Membrane Biology Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan Present address: Osborn Memorial Laboratory, Department of Molecular, Cellular and Developmental Biology, Yale University, 165 Prospect Street, New Haven, CT 6520-8104, USA Corresponding author e-mail:
| | - Keiko Shoda
- National Institute for Basic Biology/Center for Integrative Bioscience, 38 Nishigounaka, Myodaiji-cho, Okazaki 444-8585, Institute for Molecular and Cellular Biosciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai, 980-77 and Form and Function, PRESTO, Japan Science and Technology Corporation, 4-1-8 Honcho, Kawaguchi 332-0012 and School of Advanced Sciences, the Graduate University for Advanced Studies, Shonan Villege, Hayama, Kanagawa 240-0193, Japan Present address: Molecular Membrane Biology Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan Present address: Osborn Memorial Laboratory, Department of Molecular, Cellular and Developmental Biology, Yale University, 165 Prospect Street, New Haven, CT 6520-8104, USA Corresponding author e-mail:
| | - Tomohiko Tsuge
- National Institute for Basic Biology/Center for Integrative Bioscience, 38 Nishigounaka, Myodaiji-cho, Okazaki 444-8585, Institute for Molecular and Cellular Biosciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai, 980-77 and Form and Function, PRESTO, Japan Science and Technology Corporation, 4-1-8 Honcho, Kawaguchi 332-0012 and School of Advanced Sciences, the Graduate University for Advanced Studies, Shonan Villege, Hayama, Kanagawa 240-0193, Japan Present address: Molecular Membrane Biology Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan Present address: Osborn Memorial Laboratory, Department of Molecular, Cellular and Developmental Biology, Yale University, 165 Prospect Street, New Haven, CT 6520-8104, USA Corresponding author e-mail:
| | - Kiu-Hyung Cho
- National Institute for Basic Biology/Center for Integrative Bioscience, 38 Nishigounaka, Myodaiji-cho, Okazaki 444-8585, Institute for Molecular and Cellular Biosciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai, 980-77 and Form and Function, PRESTO, Japan Science and Technology Corporation, 4-1-8 Honcho, Kawaguchi 332-0012 and School of Advanced Sciences, the Graduate University for Advanced Studies, Shonan Villege, Hayama, Kanagawa 240-0193, Japan Present address: Molecular Membrane Biology Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan Present address: Osborn Memorial Laboratory, Department of Molecular, Cellular and Developmental Biology, Yale University, 165 Prospect Street, New Haven, CT 6520-8104, USA Corresponding author e-mail:
| | - Hirofumi Uchimiya
- National Institute for Basic Biology/Center for Integrative Bioscience, 38 Nishigounaka, Myodaiji-cho, Okazaki 444-8585, Institute for Molecular and Cellular Biosciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai, 980-77 and Form and Function, PRESTO, Japan Science and Technology Corporation, 4-1-8 Honcho, Kawaguchi 332-0012 and School of Advanced Sciences, the Graduate University for Advanced Studies, Shonan Villege, Hayama, Kanagawa 240-0193, Japan Present address: Molecular Membrane Biology Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan Present address: Osborn Memorial Laboratory, Department of Molecular, Cellular and Developmental Biology, Yale University, 165 Prospect Street, New Haven, CT 6520-8104, USA Corresponding author e-mail:
| | - Ryusuke Yokoyama
- National Institute for Basic Biology/Center for Integrative Bioscience, 38 Nishigounaka, Myodaiji-cho, Okazaki 444-8585, Institute for Molecular and Cellular Biosciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai, 980-77 and Form and Function, PRESTO, Japan Science and Technology Corporation, 4-1-8 Honcho, Kawaguchi 332-0012 and School of Advanced Sciences, the Graduate University for Advanced Studies, Shonan Villege, Hayama, Kanagawa 240-0193, Japan Present address: Molecular Membrane Biology Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan Present address: Osborn Memorial Laboratory, Department of Molecular, Cellular and Developmental Biology, Yale University, 165 Prospect Street, New Haven, CT 6520-8104, USA Corresponding author e-mail:
| | - Kazuhiko Nishitani
- National Institute for Basic Biology/Center for Integrative Bioscience, 38 Nishigounaka, Myodaiji-cho, Okazaki 444-8585, Institute for Molecular and Cellular Biosciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai, 980-77 and Form and Function, PRESTO, Japan Science and Technology Corporation, 4-1-8 Honcho, Kawaguchi 332-0012 and School of Advanced Sciences, the Graduate University for Advanced Studies, Shonan Villege, Hayama, Kanagawa 240-0193, Japan Present address: Molecular Membrane Biology Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan Present address: Osborn Memorial Laboratory, Department of Molecular, Cellular and Developmental Biology, Yale University, 165 Prospect Street, New Haven, CT 6520-8104, USA Corresponding author e-mail:
| | - Hirokazu Tsukaya
- National Institute for Basic Biology/Center for Integrative Bioscience, 38 Nishigounaka, Myodaiji-cho, Okazaki 444-8585, Institute for Molecular and Cellular Biosciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai, 980-77 and Form and Function, PRESTO, Japan Science and Technology Corporation, 4-1-8 Honcho, Kawaguchi 332-0012 and School of Advanced Sciences, the Graduate University for Advanced Studies, Shonan Villege, Hayama, Kanagawa 240-0193, Japan Present address: Molecular Membrane Biology Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan Present address: Osborn Memorial Laboratory, Department of Molecular, Cellular and Developmental Biology, Yale University, 165 Prospect Street, New Haven, CT 6520-8104, USA Corresponding author e-mail:
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28
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Traas J, Doonan JH. Cellular basis of shoot apical meristem development. INTERNATIONAL REVIEW OF CYTOLOGY 2002; 208:161-206. [PMID: 11510568 DOI: 10.1016/s0074-7696(01)08004-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Shoot apical meristems are composed of proliferating, embryonic type cells, that generate tissues and organs throughout the life of the plant. This review covers the cell biology of the higher plant shoot apical meristem (SAM). The first section describes the molecular basis of plant cell growth and division. The genetic mechanisms, that operate in meristem function and the identification of several key regulators of meristem behavior are described in the second section, and intercellular communication and coordination of cellular behavior in the third part. Finally, we discuss some recent results that indicate interaction between the cellular regulators, such as the cell cycle control genes and developmental regulators.
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Affiliation(s)
- J Traas
- Laboratoire de Biologie Cellulaire, Institut National de la Recherche Agronomique, Versailles, France
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29
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Ketelaar T, Emons AMC. The cytoskeleton in plant cell growth: lessons from root hairs. THE NEW PHYTOLOGIST 2001; 152:409-418. [PMID: 33862998 DOI: 10.1046/j.0028-646x.2001.00278.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
In this review, we compare expansion of intercalary growing cells, in which growth takes place over a large surface, and root hairs, where expansion occurs at the tip only. Research that pinpoints the role of the cytoskeleton and the cytoplasmic free calcium in both root hairs and intercalary growing cells is reviewed. From the results of that research, we suggest experiments to be carried out on intercalary growing cells to test our hypotheses on plant cell expansion. Our main hypothesis is that instability of the cortical actin cytoskeleton determines the location where expansion takes place and the amount of expansion. Contents Summary 409 I. How do plant cells expand their surface? 409 II. Immunolocalization of epitopes in fixed root hairs for light-microscopy 410 III. The cytoskeleton in growing root hairs 412 1. Microtubules 412 2. Actin filaments 413 3. Free cytoplasmic calcium concentration 413 IV. The role of cytoskeletal elements and cytoplasmic free alcium in intercalary expanding root cells 414 1. Microtubules 414 2. Actin filaments 415 3. Free cytoplasmic calcium concentration 416 Acknowledgements 416 References 416.
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Affiliation(s)
- Tijs Ketelaar
- Laboratory of Plant Cell Biology, Wageningen University, Arboretumlaan 4, 6703 BD Wageningen, The Netherlands; Present address: Department of Biological Sciences, University of Durham, Science Laboratories, South Road, Durham DH1 3LE, UK
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30
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Baluska F, Busti E, Dolfini S, Gavazzi G, Volkmann D. Lilliputian mutant of maize lacks cell elongation and shows defects in organization of actin cytoskeleton. Dev Biol 2001; 236:478-91. [PMID: 11476586 DOI: 10.1006/dbio.2001.0333] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The maize mutant lilliputian is characterized by miniature seedling stature, reduced cell elongation, and aberrant root anatomy. Here, we document that root cells of this mutant show several defects in the organization of actin filaments (AFs). Specifically, cells within the meristem lack dense perinuclear AF baskets and fail to redistribute AFs during mitosis. In contrast, mitotic cells of wild-type roots accumulate AFs at plasma membrane-associated domains that face the mitotic spindle poles. Both mitotic and early postmitotic mutant cells fail to assemble transverse arrays of cortical AFs, which are characteristic for wild-type root cells. In addition, early postmitotic cells show aberrant distribution of endoplasmic AF bundles that are normally organized through anchorage sites at cross-walls and nuclear surfaces. In wild-type root apices, these latter AF bundles are organized in the form of symmetrically arranged conical arrays and appear to be essential for the onset of rapid cell elongation. Exposure of wild-type and cv. Alarik maize root apices to the F-actin drugs cytochalasin D and latrunculin B mimics the phenotype of lilliputian root apices. In contrast to AFs, microtubules are more or less normally organized in root cells of lilliputian mutant. Collectively, these data suggest that the LILLIPUTIAN protein, the nature of which is still unknown, impinges on plant development via its action on the actin cytoskeleton.
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Affiliation(s)
- F Baluska
- Institute of Botany, Plant Cell Biology, University of Bonn, Kirschallee 1, D-53115 Bonn, Germany.
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31
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McClinton RS, Chandler JS, Callis J. cDNA isolation, characterization, and protein intracellular localization of a katanin-like p60 subunit from Arabidopsis thaliana. PROTOPLASMA 2001; 216:181-90. [PMID: 11732186 DOI: 10.1007/bf02673870] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Katanin, a heterodimeric protein with ATP-dependent microtubule-severing activity, localizes to the centrosome in animal cells. Widespread occurrence is suspected as several species contain homologs to the katanin p60 subunit. Recently we isolated an Arabidopsis thaliana cDNA with significant identity to the p60 subunit of sea urchin katanin. Like p60, the encoded protein is a member of the AAA superfamily of ATPases, containing the Walker ATP binding consensus and the signature AAA minimal consensus sequences within a single larger AAA/CAD amino acid motif. Phylogenetic analysis placed the encoded protein in the AAA subfamily of cytoskeleton-interactive proteins, where it formed a strongly supported clade with 4 other members identified as katanin p60 subunits. The clone was named AtKSS (Arabidopsis thaliana katanin-like protein small subunit). Western blots, performed using a polyclonal antibody raised against recombinant AtKSS, revealed AtKSS is present in protein extracts of all Arabidopsis organs examined. To evaluate potential interactions between AtKSS and the cytoskeleton, the intracellular localization of AtKSS was correlated with that of tubulin. AtKSS was found in perinuclear regions during interphase, surrounding the spindle poles during mitosis, but was absent from the preprophase band and phragmoplast microtubule arrays. These data support the thesis that AtKSS is an Arabidopsis homolog of the p60 subunit of katanin. Its cell cycle-dependent distribution is consistent with microtubule-severing activity, but additional studies will better define its role.
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Affiliation(s)
- R S McClinton
- Department of Biology, University of Louisiana at Lafayette, P.O. Box 42451, Lafayette, LA 70504-2451, USA
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32
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Brown RC, Lemmon BE. The cytoskeleton and spatial control of cytokinesis in the plant life cycle. PROTOPLASMA 2001; 215:35-49. [PMID: 11732063 DOI: 10.1007/bf01280302] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
One of the intriguing aspects of development in plants is the precise control of division plane and subsequent placement of walls resulting in the specific architecture of tissues and organs. The placement of walls can be directed by either of two microtubule cycles. The better known microtubule cycle is associated with control of the future division plane in meristematic growth where new cells become part of tissues. The future daughter domains are determined before the nucleus enters prophase and the future site of cytokinesis is marked by a preprophase band (PPB) of cortical microtubules. The spindle axis is then organized in accordance with the PPB and, following chromosome movement, a phragmoplast is initiated in the interzone and expands to join with parental walls at the site previously occupied by the PPB. The alternative microtubule cycle lacks both the hooplike cortical microtubules of interphase and the PPB. Wall placement is determined by a radial microtubule system that defines a domain of cytoplasm either containing a nucleus or destined to contain a nucleus (the nuclear cytoplasmic domain) and controls wall placement at its perimeter. This more flexible system allows for cytoplasmic polarization and migration of nuclei in coenocytes prior to cellularization. The uncoupling of cytokinesis from karyokinesis is a regular feature of the reproductive phase in plants and results in specific, often unusual, patterns of cells which reflect the position of nuclei at the time of cellularization (e.g., the arrangement of spores in a tetrad, cells of the male and female gametophytes of angiosperms, and the distinctive cellularization of endosperm). Thus, both microtubule cycles are required for completion of plant life cycles from bryophytes to angiosperms. In angiosperm seed development, the two methods of determining the boundaries of domains where walls will be deposited are operative side by side. Whereas the PPB cycle drives embryo development, the radial-microtubule-system cycle drives the common nuclear type of endosperm development from the syncytial stage through cellularization. However, a switch to the PPB cycle can occur in endosperm, as it does in barley, when peripheral cells divide to produce a multilayered aleurone. The triggers for the switch between microtubule cycles, which are currently unknown, are key to understanding plant development.
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Affiliation(s)
- R C Brown
- Department of Biology, University of Louisiana at Lafayette, LA 70504-2451, USA.
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33
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Sugimoto K, Williamson RE, Wasteneys GO. New techniques enable comparative analysis of microtubule orientation, wall texture, and growth rate in intact roots of Arabidopsis. PLANT PHYSIOLOGY 2000; 124:1493-506. [PMID: 11115865 PMCID: PMC1539303 DOI: 10.1104/pp.124.4.1493] [Citation(s) in RCA: 152] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
This article explores root epidermal cell elongation and its dependence on two structural elements of cells, cortical microtubules and cellulose microfibrils. The recent identification of Arabidopsis morphology mutants with putative cell wall or cytoskeletal defects demands a procedure for examining and comparing wall architecture and microtubule organization patterns in this species. We developed methods to examine cellulose microfibrils by field emission scanning electron microscopy and microtubules by immunofluorescence in essentially intact roots. We were able to compare cellulose microfibril and microtubule alignment patterns at equivalent stages of cell expansion. Field emission scanning electron microscopy revealed that Arabidopsis root epidermal cells have typical dicot primary cell wall structure with prominent transverse cellulose microfibrils embedded in pectic substances. Our analysis showed that microtubules and microfibrils have similar orientation only during the initial phase of elongation growth. Microtubule patterns deviate from a predominantly transverse orientation while cells are still expanding, whereas cellulose microfibrils remain transverse until well after expansion finishes. We also observed microtubule-microfibril alignment discord before cells enter their elongation phase. This study and the new technology it presents provide a starting point for further investigations on the physical properties of cell walls and their mechanisms of assembly.
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Affiliation(s)
- K Sugimoto
- Plant Cell Biology Group, Research School of Biological Sciences, Australian National University, Canberra, Australian Capital Territory 2601, Australia
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34
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Abstract
We are currently witnessing the discovery of many novel proteins that are associated with cytoskeletal activity. Integrated analyses of growth, cytoskeletal and cell-wall patterns are yielding surprising results, which demand reflection on the current model for wall construction. Meanwhile, research on actin filament and microtubule activity during gravitropic bending and trichome morphogenesis is stimulating new ideas about the establishment and maintenance of polarity.
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Affiliation(s)
- G O Wasteneys
- Plant Cell Biology Group, Research School of Biological Sciences, The Australian National University, GPO Box 475, Australian Capital Territory 2601, Canberra, Australia.
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Schwab B, Folkers U, Ilgenfritz H, Hülskamp M. Trichome morphogenesis in Arabidopsis. Philos Trans R Soc Lond B Biol Sci 2000; 355:879-83. [PMID: 11128981 PMCID: PMC1692796 DOI: 10.1098/rstb.2000.0623] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Trichomes (plant hairs) in Arabidopsis thaliana are large non-secreting epidermal cells with a characteristic three-dimensional architecture. Because trichomes are easily accessible to a combination of genetic, cell biological and molecular methods they have become an ideal model system to study various aspects of plant cell morphogenesis. In this review we will summarize recent progress in the understanding of trichome morphogenesis.
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Affiliation(s)
- B Schwab
- Zentrum Für Molekular Biologie Der Pflanzen, Entwicklungsgenetik, Universität Tübingen, Germany
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36
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Jang JC, Fujioka S, Tasaka M, Seto H, Takatsuto S, Ishii A, Aida M, Yoshida S, Sheen J. A critical role of sterols in embryonic patterning and meristem programming revealed by the fackel mutants of Arabidopsis thaliana. Genes Dev 2000. [DOI: 10.1101/gad.14.12.1485] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Here we report a novel Arabidopsis dwarf mutant,fackel-J79, whose adult morphology resembles that of brassinosteroid-deficient mutants but also displays distorted embryos, supernumerary cotyledons, multiple shoot meristems, and stunted roots. We cloned the FACKEL gene and found that it encodes a protein with sequence similarity to both the human sterol reductase family and yeast C-14 sterol reductase and is preferentially expressed in actively growing cells. Biochemical analysis indicates that the fk-J79mutation results in deficient C-14 sterol reductase activity, abnormal sterol composition, and reduction of brassinosteroids (BRs). Unlike other BR-deficient mutants, the defect of hypocotyl elongation infk-J79 cannot be corrected by exogenous BRs. The unique phenotypes and sterol composition in fk-J79 indicate crucial roles of sterol regulation and signaling in cell division and cell expansion in embryonic and post-embryonic development in plants.
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Cheng JC, Lertpiriyapong K, Wang S, Sung ZR. The role of the Arabidopsis ELD1 gene in cell development and photomorphogenesis in darkness. PLANT PHYSIOLOGY 2000; 123:509-20. [PMID: 10859181 PMCID: PMC59019 DOI: 10.1104/pp.123.2.509] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/1999] [Accepted: 02/15/2000] [Indexed: 05/18/2023]
Abstract
Because cell growth and differentiation are regulated by complex interactions among different signaling pathways, a growth defect affects subsequent differentiation. We report on a growth-defective mutant of Arabidopsis, called eld1 (elongation defective 1). Cell elongation was impaired in every organ examined. Later characteristics of the eld1 phenotype include defective vascular tissue differentiation, the inability to grow in soil, ectopic deposition of suberin around twisted vascular bundles, the de-etiolation phenotype, and continuation of shoot development and flowering in the dark. The dwarf phenotype of eld1 could not be rescued by treatment with exogenous growth regulators. Because defective cell elongation is the earliest and most universal feature detected in eld1 mutants, control of or activity in cell elongation may be the primary function of the ELD1 gene. The impaired cell growth results in pleiotropic effects on cell proliferation and differentiation, and the retardation in hypocotyl elongation enables growth and development in darkness.
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Affiliation(s)
- J C Cheng
- Department of Plant and Microbial Biology, University of California, Berkeley 94720, USA
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38
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Abstract
Growth and development of all plant cells and organs relies on a fully functional cytoskeleton comprised principally of microtubules and microfilaments. These two polymeric macromolecules, because of their location within the cell, confer structure upon, and convey information to, the peripheral regions of the cytoplasm where much of cellular growth is controlled and the formation of cellular identity takes place. Other ancillary molecules, such as motor proteins, are also important in assisting the cytoskeleton to participate in this front-line work of cellular development. Roots provide not only a ready source of cells for fundamental analyses of the cytoskeleton, but the formative zone at their apices also provides a locale whereby experimental studies can be made of how the cytoskeleton permits cells to communicate between themselves and to cooperate with growth-regulating information supplied from the apoplasm.
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Affiliation(s)
- Peter W. Barlow
- IACR-Long Ashton Research Station, Department of Agricultural Sciences, University of Bristol, Long Ashton, Bristol BS41 9AF, United Kingdom; e-mail: , Botanisches Institut, Rheinische Friedrich-Wilhelms-Universitat Bonn, Kirschallee 1, D-53115 Bonn, Germany; e-mail:
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39
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40
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Zhao L, Sack FD. Ultrastructure of stomatal development in Arabidopsis (Brassicaceae) leaves. AMERICAN JOURNAL OF BOTANY 1999. [PMID: 10406715 DOI: 10.2307/2656609] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Stomatal development was studied in wild-type Arabidopsis leaves using light and electron microscopy. Development involves three successive types of stomatal precursor cells: meristemoid mother cells, meristemoids, and guard mother cells (GMCs). The first two types divide asymmetrically, whereas GMCs divide symmetrically. Analysis of cell wall patterns indicates that meristemoids can divide asymmetrically a variable number of times. Before meristemoid division, the nucleus and a preprophase band of microtubules become located on one side of the cell, and the vacuole on the other. Meristemoids are often triangular in shape and have evenly thickened walls. GMCs can be detected by their roughly oval shape, increased starch accumulation, and wall thickenings on opposite ends of the cells. Because these features are also found in developing stomata, stomatal differentiation begins in GMCs. The wall thickenings mark the division site in the GMC since they overlie a preprophase band of microtubules and occur where the cell plate fuses with the parent cell wall. Stomatal differentiation in Arabidopsis resembles that of other genera with kidney-shaped guard cells. This identification of stages in stomatal development in wild-type Arabidopsis provides a foundation for the analysis of relevant genes and of mutants defective in stomatal patterning, cell specification, and differentiation.
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Affiliation(s)
- L Zhao
- Department of Plant Biology, Ohio State University, 1735 Neil Avenue, Columbus, Ohio 43210
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41
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Pickett-Heaps JD, Gunning BE, Brown RC, Lemmon BE, Cleary AL. The cytoplast concept in dividing plant cells: cytoplasmic domains and the evolution of spatially organized cell. AMERICAN JOURNAL OF BOTANY 1999. [PMID: 21680355 DOI: 10.2307/2656933] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The unique cytokinetic apparatus of higher plant cells comprises two cytoskeletal systems: a predictive preprophase band of microtubules (MTs), which defines the future division site, and the phragmoplast, which mediates crosswall formation after mitosis. We review features of plant cell division in an evolutionary context and from the viewpoint that the cell is a domain of cytoplasm (cytoplast) organized around the nucleus by a cytoskeleton consisting of a single "tensegral" unit. The term "tensegrity" is a contraction of "tensional integrity" and the concept proposes that the whole cell is organized by an integrated cytoskeleton of tension elements (e.g., actin fibers) extended over compression-resistant elements (e.g., MTs).During cell division, a primary role of the spindle is seen as generating two cytoplasts from one with separation of chromosomes a later, derived function. The telophase spindle separates the newly forming cytoplasts and the overlap between half spindles (the shared edge of two new domains) dictates the position at which cytokinesis occurs. Wall MTs of higher plant cells, like the MT cytoskeleton in animal and protistan cells, spatially define the interphase cytoplast. Redeployment of actin and MTs into the preprophase band (PPB) is the overt signal that the boundary between two nascent cytoplasts has been delineated. The "actin-depleted zone" that marks the site of the PPB throughout mitosis may be a more persistent manifestation of this delineation of two domains of cortical actin. The growth of the phragmoplast is controlled by these domains, not just by the spindle. These domains play a major role in controlling the path of phragmoplast expansion. Primitive land plants show different morphological changes that reveal that the plane of division, with or without the PPB, has been determined well in advance of mitosis.The green alga Spirogyra suggests how the phragmoplast system might have evolved: cytokinesis starts with cleavage and then actin-related determinants stimulate and positionally control cell-plate formation in a phragmoplast arising from interzonal MTs from the spindle. Actin in the PPB of higher plants may be assembling into a potential furrow, imprinting a cleavage site whose persistent determinants (perhaps actin) align the outgrowing edge of the phragmoplast, as in Spirogyra. Cytochalasin spatially disrupts polarized mitosis and positioning of the phragmoplast. Thus, the tensegral interaction of actin with MTs (at the spindle pole and in the phragmoplast) is critical to morphogenesis, just as they seem to be during division of animal cells. In advanced green plants, intercalary expansion driven by turgor is controlled by MTs, which in conjunction with actin, may act as stress detectors, thereby affecting the plane of division (a response clearly evident after wounding of tissue). The PPB might be one manifestation of this strain detection apparatus.
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Affiliation(s)
- J D Pickett-Heaps
- School of Botany, University of Melbourne, Parkville, Victoria 3052, Australia
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42
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Mayer U, Herzog U, Berger F, Inzé D, Jürgens G. Mutations in the pilz group genes disrupt the microtubule cytoskeleton and uncouple cell cycle progression from cell division in Arabidopsis embryo and endosperm. Eur J Cell Biol 1999; 78:100-8. [PMID: 10099932 DOI: 10.1016/s0171-9335(99)80011-9] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Organised cell division and expansion play important roles in plant embryogenesis. To address their cellular basis, we have analysed Arabidopsis abnormal-embryo mutants which were isolated for their characteristic phenotype: mutant embryos are small, mushroom-shaped ("pilz") and consist of only one or few large cells each containing one or more variably enlarged nuclei and often cell wall stubs. These 23 mutants represent four genes, PFIFFERLING, HALLIMASCH, CHAMPIGNON, and PORCINO, which map to different chromosomes. All four genes have very similar mutant phenotypes although porcino embryos often consisted of only one large cell. The endosperm did not cellularise and contained a variably reduced number of highly enlarged nuclei. By contrast, genetic evidence suggests that these genes are not required for gametophyte development. Expression of cell cycle genes, Cdc2a, CyclinA2 and CyclinB1, and the cytokinesis-specific KNOLLE gene was not altered in mutant embryos. However, KNOLLE syntaxin accumulated in patches but no KNOLLE-positive structure resembling a forming cell plate occurred in mitotic cells. A general defect in microtubule assembly was observed in all mutants. Interphase cells lacked cortical microtubules, and spindles were absent from mitotic nuclei although in rare cases, short stubs of microtubules were attached to partially condensed chromosomes. Our results suggest that the cellular components affected by the pilz group mutations are necessary for continuous microtubule organisation, mitotic division and cytokinesis but do not mediate cell cycle progression.
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Affiliation(s)
- U Mayer
- Lehrstuhl für Entwicklungsgenetik, Universität Tübingen, Germany.
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43
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Hülskamp M, Schnittger A, Folkers U. Pattern formation and cell differentiation: trichomes in Arabidopsis as a genetic model system. INTERNATIONAL REVIEW OF CYTOLOGY 1998; 186:147-78. [PMID: 9770299 DOI: 10.1016/s0074-7696(08)61053-0] [Citation(s) in RCA: 100] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Arabidopsis trichomes are single-celled hairs that originate from epidermal cells and are distributed regularly on most aerial body parts. During the last decade, trichome formation in Arabidopsis has been established as a genetic and molecular model system to study various general developmental and cellular mechanisms. This review summarizes progress in the investigation of several aspects of trichome development: the spatial regulation of cell fate determination, the regulation of cell differentiation in response to exogenous signals and plant hormones, and the regulation of endoreplication, cell growth, and cell morphogenesis.
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Affiliation(s)
- M Hülskamp
- Lehrstuhl für Entwicklungsgenetik, Universität Tübingen, Germany
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44
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Liu CM, Meinke DW. The titan mutants of Arabidopsis are disrupted in mitosis and cell cycle control during seed development. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 1998; 16:21-31. [PMID: 9807824 DOI: 10.1046/j.1365-313x.1998.00268.x] [Citation(s) in RCA: 168] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
We describe in this report a novel class of mutants that should facilitate the identification of genes required for progression through the mitotic cell cycle during seed development in angiosperms. Three non-allelic titan (ttn) mutants with related but distinct phenotypes are characterized. The common feature among these mutants is that endosperm nuclei become greatly enlarged and highly polyploid. The mutant embryo is composed of a few giant cells in ttn1, several small cells in ttn2, and produces a normal plant in ttn3. Condensed chromosomes arrested at prophase of mitosis are found in the free nuclear endosperm of ttn1 and ttn2 seeds. Large mitotic figures with excessive numbers of chromosomes are visible in ttn3 endosperm. The ttn1 mutation appears to disrupt cytoskeletal organization because endosperm nuclei fail to migrate to the chalazal end of the seed. How double fertilization leads to the establishment of distinct patterns of mitosis and cytokinesis in the embryo and endosperm is a central question in plant reproductive biology. Molecular isolation of TITAN genes should help to answer this question, as well as related issues concerning cell cycle regulation, chromosome movement and endosperm identity in angiosperms.
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Affiliation(s)
- C M Liu
- Department of Botany, Oklahoma State University, Stillwater 74078, USA
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45
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Vaughn KC, Harper JD. Microtubule-organizing centers and nucleating sites in land plants. INTERNATIONAL REVIEW OF CYTOLOGY 1998; 181:75-149. [PMID: 9522456 DOI: 10.1016/s0074-7696(08)60417-9] [Citation(s) in RCA: 95] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Microtubule-organizing centers (MTOCs) are morphologically diverse cellular sites involved in the nucleation and organization of microtubules (MTs). These structures are synonymous with the centrosome in mammalian cells. In most land plant cells, however, no such structures are observed and some have argued that plant cells may not have MTOCs. This review summarizes a number of experimental approaches toward the elucidation of those subcellular sites involved in microtubule nucleation and organization. In lower land plants, structurally well-defined MTOCs are present, such as the blepharoplast, multilayered structure, and polar organizer. In higher plants, much of the nucleation and organization of MTs occurs on the nuclear envelope or other endomembranes, such as the plasmalemma and smooth (tubular) endoplasmic reticulum. In some instances, one endomembrane may serve as a site of nucleation whereas others serve as the site of organization. Structural and motor microtubule-associated proteins also appear to be involved in MT nucleation and organization. Immunochemical evidence indicates that at least several of the proteins found in mammalian centrosomes, gamma-tubulin, centrin, pericentrin, and polypeptides recognized by the monoclonal antibodies MPM-2, 6C6, and C9 also recognize putative lower land plant MTOCs, indicating shared mechanisms of nucleation/organization in plants and animals. The most recent data from tubulin incorporation in vivo, mutants with altered MT organization, and molecular studies indicate the potential of these research tools in investigation of MTOCs in plants.
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Affiliation(s)
- K C Vaughn
- Southern Weed Science Laboratory, USDA-ARS, Stoneville, Mississippi 38776, USA
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46
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Abstract
There are two quite different modes of polar cell expansion in plant cells, namely, diffuse growth and tip growth. The direction of diffuse growth is determined by the orientation of cellulose microfibrils in the cell wall, which in turn are aligned by microtubules in the cell cortex. The orientation of the cortical microtubule array changes in response to developmental and environmental signals, and recent evidence indicates that microtubule disassembly/reassembly and microtubule translocation participate in reorientation of the array. Tip growth, in contrast, is governed mainly by F-actin, which has several putative forms and functions in elongating cells. Longitudinal cables are involved in vesicle transport to the expanding apical dome and, in some tip growers, a subapical ring of F-actin may participate in wall-membrane adhesions. The structure and function of F-actin within the apical dome may be variable, ranging from a dense meshwork to sparse single filaments. The presence of multiple F-actin structures in elongating tips suggests extensive regulation of this cytoskeletal array.
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Affiliation(s)
- D L Kropf
- University of Utah, Department of Biology, Salt Lake City 84112-0840, USA.
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47
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Abstract
Cell morphogenesis encompasses all processes required to establish a three-dimensional cell shape. Cells acquire the architecture specific to their developmental context by using the spatial information provided by internal or external cues. As a response to these signals, cells become reorganized and establish functionally distinct subcellular domains that ultimately lead to morphological changes. In its simplest form, cell morphogenesis results in the establishment of asymmetry along one axis, a cell polarity. Although cell polarity has been studied intensively in budding yeast and epithelial cells, little is known about more complex modes of cell morphogenesis involving multiple axes. In this review we compare the regulation of cell morphogenesis of different genetically well-characterized cell types in Arabidopsis thaliana.
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Affiliation(s)
- M Hülskamp
- Lehrstuhl für Entwicklungsgenetik, Universität Tübingen, Germany. huelskamp@uni-tuebingen
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