1
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Chocano-Coralla EJ, Vidali L. Myosin XI, a model of its conserved role in plant cell tip growth. Biochem Soc Trans 2024; 52:505-515. [PMID: 38629612 DOI: 10.1042/bst20220783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 03/21/2024] [Accepted: 03/26/2024] [Indexed: 04/25/2024]
Abstract
In eukaryotic cells, organelle and vesicle transport, positioning, and interactions play crucial roles in cytoplasmic organization and function. These processes are governed by intracellular trafficking mechanisms. At the core of that trafficking, the cytoskeleton and directional transport by motor proteins stand out as its key regulators. Plant cell tip growth is a well-studied example of cytoplasm organization by polarization. This polarization, essential for the cell's function, is driven by the cytoskeleton and its associated motors. This review will focus on myosin XI, a molecular motor critical for vesicle trafficking and polarized plant cell growth. We will center our discussion on recent data from the moss Physcomitrium patens and the liverwort Marchantia polymorpha. The biochemical properties and structure of myosin XI in various plant species are discussed, highlighting functional conservation across species. We further explore this conservation of myosin XI function in the process of vesicle transport in tip-growing cells. Existing evidence indicates that myosin XI actively organizes actin filaments in tip-growing cells by a mechanism based on vesicle clustering at their tips. A hypothetical model is presented to explain the essential function of myosin XI in polarized plant cell growth based on vesicle clustering at the tip. The review also provides insight into the in vivo localization and dynamics of myosin XI, emphasizing its role in cytosolic calcium regulation, which influences the polymerization of F-actin. Lastly, we touch upon the need for additional research to elucidate the regulation of myosin function.
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Affiliation(s)
| | - Luis Vidali
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, MA, U.S.A
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2
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Phillips TA, Marcotti S, Cox S, Parsons M. Imaging actin organisation and dynamics in 3D. J Cell Sci 2024; 137:jcs261389. [PMID: 38236161 PMCID: PMC10906668 DOI: 10.1242/jcs.261389] [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] [Indexed: 01/19/2024] Open
Abstract
The actin cytoskeleton plays a critical role in cell architecture and the control of fundamental processes including cell division, migration and survival. The dynamics and organisation of F-actin have been widely studied in a breadth of cell types on classical two-dimensional (2D) surfaces. Recent advances in optical microscopy have enabled interrogation of these cytoskeletal networks in cells within three-dimensional (3D) scaffolds, tissues and in vivo. Emerging studies indicate that the dimensionality experienced by cells has a profound impact on the structure and function of the cytoskeleton, with cells in 3D environments exhibiting cytoskeletal arrangements that differ to cells in 2D environments. However, the addition of a third (and fourth, with time) dimension leads to challenges in sample preparation, imaging and analysis, necessitating additional considerations to achieve the required signal-to-noise ratio and spatial and temporal resolution. Here, we summarise the current tools for imaging actin in a 3D context and highlight examples of the importance of this in understanding cytoskeletal biology and the challenges and opportunities in this domain.
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Affiliation(s)
- Thomas A. Phillips
- Randall Centre for Cell and Molecular Biophysics, King's College London, New Hunts House, Guys Campus, London SE1 1UL, UK
| | - Stefania Marcotti
- Randall Centre for Cell and Molecular Biophysics, King's College London, New Hunts House, Guys Campus, London SE1 1UL, UK
- Microscopy Innovation Centre, King's College London, Guys Campus, London SE1 1UL, UK
| | - Susan Cox
- Randall Centre for Cell and Molecular Biophysics, King's College London, New Hunts House, Guys Campus, London SE1 1UL, UK
| | - Maddy Parsons
- Randall Centre for Cell and Molecular Biophysics, King's College London, New Hunts House, Guys Campus, London SE1 1UL, UK
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3
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Tang H, Lu KJ, Zhang Y, Cheng YL, Tu SL, Friml J. Divergence of trafficking and polarization mechanisms for PIN auxin transporters during land plant evolution. PLANT COMMUNICATIONS 2024; 5:100669. [PMID: 37528584 PMCID: PMC10811345 DOI: 10.1016/j.xplc.2023.100669] [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: 01/06/2023] [Revised: 07/03/2023] [Accepted: 07/30/2023] [Indexed: 08/03/2023]
Abstract
The phytohormone auxin, and its directional transport through tissues, plays a fundamental role in the development of higher plants. This polar auxin transport predominantly relies on PIN-FORMED (PIN) auxin exporters. Hence, PIN polarization is crucial for development, but its evolution during the rise of morphological complexity in land plants remains unclear. Here, we performed a cross-species investigation by observing the trafficking and localization of endogenous and exogenous PINs in two bryophytes, Physcomitrium patens and Marchantia polymorpha, and in the flowering plant Arabidopsis thaliana. We confirmed that the GFP fusion did not compromise the auxin export function of all examined PINs by using a radioactive auxin export assay and by observing the phenotypic changes in transgenic bryophytes. Endogenous PINs polarize to filamentous apices, while exogenous Arabidopsis PINs distribute symmetrically on the membrane in both bryophytes. In the Arabidopsis root epidermis, bryophytic PINs have no defined polarity. Pharmacological interference revealed a strong cytoskeletal dependence of bryophytic but not Arabidopsis PIN polarization. The divergence of PIN polarization and trafficking is also observed within the bryophyte clade and between tissues of individual species. These results collectively reveal the divergence of PIN trafficking and polarity mechanisms throughout land plant evolution and the co-evolution of PIN sequence-based and cell-based polarity mechanisms.
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Affiliation(s)
- Han Tang
- Institute of Science and Technology Austria (ISTA), Am Campus 1, 3400 Klosterneuburg, Austria
| | - Kuan-Ju Lu
- Graduate Institute of Biotechnology, National Chung Hsing University, No. 145, Xingda Rd., South Dist., Taichung 40227, Taiwan, R.O.C
| | - YuZhou Zhang
- College of Life Sciences, Northwest A&F University, Shaanxi, Yangling, China
| | - You-Liang Cheng
- Institute of Plant and Microbial Biology, Academia Sinica, 128 Sec. 2, Academia Rd, Nankang, Taipei 11529, Taiwan, R.O.C
| | - Shih-Long Tu
- Institute of Plant and Microbial Biology, Academia Sinica, 128 Sec. 2, Academia Rd, Nankang, Taipei 11529, Taiwan, R.O.C
| | - Jiří Friml
- Institute of Science and Technology Austria (ISTA), Am Campus 1, 3400 Klosterneuburg, Austria.
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4
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Cui X, Zou M, Li J. Basally distributed actin array drives embryonic hypocotyl elongation during the seed-to-seedling transition in Arabidopsis. THE NEW PHYTOLOGIST 2023; 240:191-206. [PMID: 37537721 DOI: 10.1111/nph.19149] [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: 02/14/2023] [Accepted: 06/27/2023] [Indexed: 08/05/2023]
Abstract
Seed germination is a vital developmental transition for the production of progeny by sexual reproduction in spermatophytes. The seed-to-seedling transition is predominately driven by hypocotyl cell elongation. However, the mechanism that underlies hypocotyl growth remains largely unknown. In this study, we characterized the actin array reorganization in embryonic hypocotyl epidermal cells. Live-cell imaging revealed a basally organized actin array formed during hypocotyl cell elongation. This polarized actin assembly is a barrel-shaped network, which comprises a backbone of longitudinally aligned actin cables and a fine actin cap linking these cables. We provide genetic evidence that the basal actin array formation requires formin-mediated actin polymerization and directional movement of actin filaments powered by myosin XIs. In fh1-1 and xi3ko mutants, actin filaments failed to reorganize into the basal actin array, and the hypocotyl cell elongation was inhibited compared with wild-type plants. Collectively, our work uncovers the molecular mechanisms for basal actin array assembly and demonstrates the connection between actin polarization and hypocotyl elongation during seed-to-seedling transition.
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Affiliation(s)
- Xuan Cui
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Science, Beijing Normal University, Beijing, 100875, China
| | - Minxia Zou
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Science, Beijing Normal University, Beijing, 100875, China
| | - Jiejie Li
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Science, Beijing Normal University, Beijing, 100875, China
- Key Laboratory of Cell Proliferation and Regulation of Ministry of Education, College of Life Science, Beijing Normal University, Beijing, 100875, China
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5
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Zhang R, Xu Y, Yi R, Shen J, Huang S. Actin cytoskeleton in the control of vesicle transport, cytoplasmic organization, and pollen tube tip growth. PLANT PHYSIOLOGY 2023; 193:9-25. [PMID: 37002825 DOI: 10.1093/plphys/kiad203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 03/08/2023] [Accepted: 03/17/2023] [Indexed: 06/19/2023]
Abstract
Pollen tubes extend rapidly via tip growth. This process depends on a dynamic actin cytoskeleton, which has been implicated in controlling organelle movements, cytoplasmic streaming, vesicle trafficking, and cytoplasm organization in pollen tubes. In this update review, we describe the progress in understanding the organization and regulation of the actin cytoskeleton and the function of the actin cytoskeleton in controlling vesicle traffic and cytoplasmic organization in pollen tubes. We also discuss the interplay between ion gradients and the actin cytoskeleton that regulates the spatial arrangement and dynamics of actin filaments and the organization of the cytoplasm in pollen tubes. Finally, we describe several signaling components that regulate actin dynamics in pollen tubes.
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Affiliation(s)
- Ruihui Zhang
- National Key Laboratory of Crop Genetic Improvement, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Yanan Xu
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Ran Yi
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Jiangfeng Shen
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Shanjin Huang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
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6
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Wu SZ, Chaves AM, Li R, Roberts AW, Bezanilla M. Cellulose synthase-like D movement in the plasma membrane requires enzymatic activity. J Cell Biol 2023; 222:e202212117. [PMID: 37071416 PMCID: PMC10120407 DOI: 10.1083/jcb.202212117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 02/28/2023] [Accepted: 03/17/2023] [Indexed: 04/19/2023] Open
Abstract
Cellulose Synthase-Like D (CSLD) proteins, important for tip growth and cell division, are known to generate β-1,4-glucan. However, whether they are propelled in the membrane as the glucan chains they produce assemble into microfibrils is unknown. To address this, we endogenously tagged all eight CSLDs in Physcomitrium patens and discovered that they all localize to the apex of tip-growing cells and to the cell plate during cytokinesis. Actin is required to target CSLD to cell tips concomitant with cell expansion, but not to cell plates, which depend on actin and CSLD for structural support. Like Cellulose Synthase (CESA), CSLD requires catalytic activity to move in the plasma membrane. We discovered that CSLD moves significantly faster, with shorter duration and less linear trajectories than CESA. In contrast to CESA, CSLD movement was insensitive to the cellulose synthesis inhibitor isoxaben, suggesting that CSLD and CESA function within different complexes possibly producing structurally distinct cellulose microfibrils.
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Affiliation(s)
- Shu-Zon Wu
- Department of Biological Sciences, Dartmouth College, Hanover, NH, USA
| | - Arielle M. Chaves
- Department of Biological Sciences, University of Rhode Island, Kingston, RI, USA
| | - Rongrong Li
- Department of Biological Sciences, University of Rhode Island, Kingston, RI, USA
| | - Alison W. Roberts
- Department of Biological Sciences, University of Rhode Island, Kingston, RI, USA
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7
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Weng X, Shen Y, Jiang L, Zhao L, Wang H. Spatiotemporal organization and correlation of tip-focused exocytosis and endocytosis in regulating pollen tube tip growth. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2023; 330:111633. [PMID: 36775070 DOI: 10.1016/j.plantsci.2023.111633] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 01/09/2023] [Accepted: 02/07/2023] [Indexed: 06/18/2023]
Abstract
Pollen tube polar growth is a key cellular process during plant fertilization and is regulated by tip-focused exocytosis and endocytosis. However, the spatiotemporal dynamics and localizations of apical exocytosis and endocytosis in the tip region are still a matter of debate. Here, we use a refined spinning-disk confocal microscope coupled with fluorescence recovery after photobleaching for sustained live imaging and quantitative analysis of rapid vesicular activities in growing pollen tube tips. We traced and analyzed the occurrence site of exocytic plasma membrane-targeting of Arabidopsis secretory carrier membrane protein 4 and its subsequent endocytosis in tobacco pollen tube tips. We demonstrated that the pollen tube apex is the site for both vesicle polar exocytic fusion and endocytosis to take place. In addition, we disrupted either tip-focused exocytosis or endocytosis and found that their dynamic activities are closely correlated with one another basing on the spatial organization of actin fringe. Collectively, our findings attempt to propose a new exocytosis and endocytosis-coordinated yin-yang working model underlying the apical membrane organization and dynamics during pollen tube tip growth.
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Affiliation(s)
- Xun Weng
- College of Life Sciences, South China Agricultural University, Guangzhou 510642, China
| | - Yifan Shen
- Utahloy International School of Guangzhou, Guangzhou 510642, China
| | - Liwen Jiang
- School of Life Sciences, Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China; Institute of Plant Molecular Biology & Agricultural Biotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - Lifeng Zhao
- College of Life Sciences, South China Agricultural University, Guangzhou 510642, China.
| | - Hao Wang
- College of Life Sciences, South China Agricultural University, Guangzhou 510642, China.
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8
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Dávila-Delgado R, Flores-Canúl K, Juárez-Verdayes MA, Sánchez-López R. Rhizobia induce SYMRK endocytosis in Phaseolus vulgaris root hair cells. PLANTA 2023; 257:83. [PMID: 36928335 PMCID: PMC10020325 DOI: 10.1007/s00425-023-04116-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Accepted: 03/06/2023] [Indexed: 06/18/2023]
Abstract
PvSYMRK-EGFP undergoes constitutive and rhizobia-induced endocytosis, which rely on the phosphorylation status of T589, the endocytic YXXØ motif and the kinase activity of the receptor. Legume-rhizobia nodulation is a complex developmental process. It initiates when the rhizobia-produced Nod factors are perceived by specific LysM receptors present in the root hair apical membrane. Consequently, SYMRK (Symbiosis Receptor-like Kinase) becomes active in the root hair and triggers an extensive signaling network essential for the infection process and nodule organogenesis. Despite its relevant functions, the underlying cellular mechanisms involved in SYMRK signaling activity remain poorly characterized. In this study, we demonstrated that PvSYMRK-EGFP undergoes constitutive and rhizobia-induced endocytosis. We found that in uninoculated roots, PvSYMRK-EGFP is mainly associated with the plasma membrane, although intracellular puncta labelled with PvSymRK-EGFP were also observed in root hair and nonhair-epidermal cells. Inoculation with Rhizobium etli producing Nod factors induces in the root hair a redistribution of PvSYMRK-EGFP from the plasma membrane to intracellular puncta. In accordance, deletion of the endocytic motif YXXØ (YKTL) and treatment with the endocytosis inhibitors ikarugamycin (IKA) and tyrphostin A23 (TyrA23), as well as brefeldin A (BFA), drastically reduced the density of intracellular PvSYMRK-EGFP puncta. A similar effect was observed in the phosphorylation-deficient (T589A) and kinase-dead (K618E) mutants of PvSYMRK-EGFP, implying these structural features are positive regulators of PvSYMRK-EGFP endocytosis. Our findings lead us to postulate that rhizobia-induced endocytosis of SYMRK modulates the duration and amplitude of the SYMRK-dependent signaling pathway.
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Affiliation(s)
- Raúl Dávila-Delgado
- Departamento de Biología Molecular de Plantas, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenida Universidad 2001, Colonia Chamilpa, 62210 Cuernavaca, Morelos Mexico
| | - Karen Flores-Canúl
- Departamento de Biología Molecular de Plantas, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenida Universidad 2001, Colonia Chamilpa, 62210 Cuernavaca, Morelos Mexico
| | - Marco Adán Juárez-Verdayes
- Departamento de Biología Molecular de Plantas, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenida Universidad 2001, Colonia Chamilpa, 62210 Cuernavaca, Morelos Mexico
| | - Rosana Sánchez-López
- Departamento de Biología Molecular de Plantas, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenida Universidad 2001, Colonia Chamilpa, 62210 Cuernavaca, Morelos Mexico
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9
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Yoshida MW, Kozgunova E. Microfluidic Device for High-Resolution Cytoskeleton Imaging and Washout Assays in Physcomitrium (Physcomitrella) patens. Methods Mol Biol 2023; 2604:143-158. [PMID: 36773231 DOI: 10.1007/978-1-0716-2867-6_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
Visualizing cytoskeleton dynamics at high spatiotemporal resolution provides valuable insights into the way the dynamics change as well as its interactions with multiple proteins in order to maintain cellular function. Oblique illumination fluorescent microscopy is a popular technique to image cellular events localized near the plasma membrane. In this chapter, we provide detailed protocols for high-resolution cytoskeleton imaging using protonema and gametophore cells of the moss Physcomitrella (Physcomitrium patens) in the microfluidic device. These include preparation of the polydimethylsiloxane (PDMS) device, culture of moss cells, and both short- and long-term oblique illumination fluorescent microscopy. We also describe how to introduce to, and wash out from, the device chemical compounds, such as microtubule-disrupting drugs, during live-cell imaging.
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Affiliation(s)
- Mari W Yoshida
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi, Japan
| | - Elena Kozgunova
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi, Japan. .,Institute for Advanced Research, Nagoya University, Nagoya, Japan.
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10
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Lu Q, Liu X, Qu X, Huang S. Visualization and Quantification of the Dynamics of Actin Filaments in Arabidopsis Pollen Tubes. Methods Mol Biol 2023; 2604:285-295. [PMID: 36773243 DOI: 10.1007/978-1-0716-2867-6_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
The actin cytoskeleton plays an essential role in the regulation of polarized pollen tube growth, and its functions are dictated by its spatial organization and dynamics. Here we describe an assay to monitor the dynamics of actin filaments decorated with Lifeact-mEGFP in Arabidopsis pollen tubes using spinning disk confocal microscopy and measuring the parameters associated with their dynamics. The method allows us to assess the dynamics of actin filaments in growing Arabidopsis pollen tubes.
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Affiliation(s)
- Qiaonan Lu
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Xiaonan Liu
- School of Life Sciences, Qilu Normal University, Jinan, China
| | - Xiaolu Qu
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, China.
| | - Shanjin Huang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China.
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11
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Zhu L, Fu Y. Investigation of ROP GTPase Activity and Cytoskeleton Dynamics During Tip Growth in Root Hairs and Pollen Tubes. Methods Mol Biol 2023; 2604:227-235. [PMID: 36773237 DOI: 10.1007/978-1-0716-2867-6_17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
Pollen tubes and root hairs are typical tip-growing cells and are employed as model systems to study plant cell polarity. Previous studies have shown that the Rho family ROP GTPase plays a critical role in the regulation of pollen tube and root hair growth. Periodically, activated ROP GTPase coordinates with the tip-focused calcium gradient, to regulate actin dynamics and vesicle trafficking. Moreover, microtubules are also involved in organelle movement and growth directionality. Here, we describe methods for analyzing the spatiotemporal localization and activity of ROP, cortical microtubule organization, and F-actin dynamics in pollen tubes and/or root hairs.
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Affiliation(s)
- Lei Zhu
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, China.
| | - Ying Fu
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, China
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12
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Stroppa N, Onelli E, Moreau P, Maneta-Peyret L, Berno V, Cammarota E, Ambrosini R, Caccianiga M, Scali M, Moscatelli A. Sterols and Sphingolipids as New Players in Cell Wall Building and Apical Growth of Nicotiana tabacum L. Pollen Tubes. PLANTS (BASEL, SWITZERLAND) 2022; 12:8. [PMID: 36616135 PMCID: PMC9824051 DOI: 10.3390/plants12010008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 12/05/2022] [Accepted: 12/12/2022] [Indexed: 06/17/2023]
Abstract
Pollen tubes are tip-growing cells that create safe routes to convey sperm cells to the embryo sac for double fertilization. Recent studies have purified and biochemically characterized detergent-insoluble membranes from tobacco pollen tubes. These microdomains, called lipid rafts, are rich in sterols and sphingolipids and are involved in cell polarization in organisms evolutionarily distant, such as fungi and mammals. The presence of actin in tobacco pollen tube detergent-insoluble membranes and the preferential distribution of these domains on the apical plasma membrane encouraged us to formulate the intriguing hypothesis that sterols and sphingolipids could be a "trait d'union" between actin dynamics and polarized secretion at the tip. To unravel the role of sterols and sphingolipids in tobacco pollen tube growth, we used squalestatin and myriocin, inhibitors of sterol and sphingolipid biosynthesis, respectively, to determine whether lipid modifications affect actin fringe morphology and dynamics, leading to changes in clear zone organization and cell wall deposition, thus suggesting a role played by these lipids in successful fertilization.
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Affiliation(s)
- Nadia Stroppa
- Dipartimento di Bioscienze, Università degli Studi di Milano, Via Celoria 26, 20133 Milan, Italy
| | - Elisabetta Onelli
- Dipartimento di Bioscienze, Università degli Studi di Milano, Via Celoria 26, 20133 Milan, Italy
| | - Patrick Moreau
- CNRS, Laboratoire de Biogenèse Membranaire, University of Bordeaux, UMR 5200, 71 Avenue Edouard Bourlaux, 33140 Villenave d’Ornon, France
| | - Lilly Maneta-Peyret
- CNRS, Laboratoire de Biogenèse Membranaire, University of Bordeaux, UMR 5200, 71 Avenue Edouard Bourlaux, 33140 Villenave d’Ornon, France
| | - Valeria Berno
- ALEMBIC Advanced Light and Electron Microscopy BioImaging Center, San Raffaele Scientific Institute, DIBIT 1, Via Olgettina 58, 20132 Milan, Italy
| | - Eugenia Cammarota
- ALEMBIC Advanced Light and Electron Microscopy BioImaging Center, San Raffaele Scientific Institute, DIBIT 1, Via Olgettina 58, 20132 Milan, Italy
| | - Roberto Ambrosini
- Dipartimento di Scienze e Politiche Ambientali, Università degli Studi di Milano, Via Celoria 26, 20133 Milan, Italy
| | - Marco Caccianiga
- Dipartimento di Bioscienze, Università degli Studi di Milano, Via Celoria 26, 20133 Milan, Italy
| | - Monica Scali
- Dipartimento di Scienze della Vita, Università degli Studi di Siena, Via Aldo Moro 2, 53100 Siena, Italy
| | - Alessandra Moscatelli
- Dipartimento di Bioscienze, Università degli Studi di Milano, Via Celoria 26, 20133 Milan, Italy
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13
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Guo K, Huang C, Miao Y, Cosgrove DJ, Hsia KJ. Leaf morphogenesis: The multifaceted roles of mechanics. MOLECULAR PLANT 2022; 15:1098-1119. [PMID: 35662674 DOI: 10.1016/j.molp.2022.05.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 05/18/2022] [Accepted: 05/26/2022] [Indexed: 05/12/2023]
Abstract
Plants produce a rich diversity of biological forms, and the diversity of leaves is especially notable. Mechanisms of leaf morphogenesis have been studied in the past two decades, with a growing focus on the interactive roles of mechanics in recent years. Growth of plant organs involves feedback by mechanical stress: growth induces stress, and stress affects growth and morphogenesis. Although much attention has been given to potential stress-sensing mechanisms and cellular responses, the mechanical principles guiding morphogenesis have not been well understood. Here we synthesize the overarching roles of mechanics and mechanical stress in multilevel and multiple stages of leaf morphogenesis, encompassing leaf primordium initiation, phyllotaxis and venation patterning, and the establishment of complex mature leaf shapes. Moreover, the roles of mechanics at multiscale levels, from subcellular cytoskeletal molecules to single cells to tissues at the organ scale, are articulated. By highlighting the role of mechanical buckling in the formation of three-dimensional leaf shapes, this review integrates the perspectives of mechanics and biology to provide broader insights into the mechanobiology of leaf morphogenesis.
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Affiliation(s)
- Kexin Guo
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798, Singapore
| | - Changjin Huang
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798, Singapore
| | - Yansong Miao
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Daniel J Cosgrove
- Department of Biology, The Pennsylvania State University, University Park, PA 16802, USA.
| | - K Jimmy Hsia
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798, Singapore; School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 637459, Singapore.
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14
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Liu Z, Østerlund I, Ruhnow F, Cao Y, Huang G, Cai W, Zhang J, Liang W, Nikoloski Z, Persson S, Zhang D. Fluorescent cytoskeletal markers reveal associations between the actin and microtubule cytoskeleton in rice cells. Development 2022; 149:275467. [DOI: 10.1242/dev.200415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 05/09/2022] [Indexed: 11/20/2022]
Abstract
ABSTRACT
Rice (Oryza sativa) is one of our main food crops, feeding ∼3.5 billion people worldwide. An increasing number of studies note the importance of the cytoskeleton, including actin filaments and microtubules, in rice development and environmental responses. Yet, reliable in vivo cytoskeleton markers are lacking in rice, which limits our knowledge of cytoskeletal functions in living cells. Therefore, we generated bright fluorescent marker lines of the actin and microtubule cytoskeletons in rice, suitable for live-cell imaging in a wide variety of rice tissues. Using these lines, we show that actin bundles and microtubules engage and co-function during pollen grain development, how the cytoskeletal components are coordinated during root cell development, and that the actin cytoskeleton is robust and facilitates microtubule responses during salt stress. Hence, we conclude that our cytoskeletal marker lines, highlighted by our findings of cytoskeletal associations and dynamics, will substantially further future investigations in rice biology.
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Affiliation(s)
- Zengyu Liu
- Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University 1 , Minhang 200240, Shanghai , China
| | - Isabella Østerlund
- University of Copenhagen 2 Department of Plant and Environmental Sciences (PLEN) , , 1870 Frederiksberg , Denmark
- Max Planck Institute of Molecular Plant Physiology 3 Systems Biology and Mathematical Modelling , , Am Mühlenberg 1, 14476 Potsdam-Golm , Germany
| | - Felix Ruhnow
- University of Copenhagen 2 Department of Plant and Environmental Sciences (PLEN) , , 1870 Frederiksberg , Denmark
| | - Yiran Cao
- Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University 1 , Minhang 200240, Shanghai , China
| | - Guoqiang Huang
- Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University 1 , Minhang 200240, Shanghai , China
| | - Wenguo Cai
- Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University 1 , Minhang 200240, Shanghai , China
| | - Jiao Zhang
- Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University 1 , Minhang 200240, Shanghai , China
| | - Wanqi Liang
- Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University 1 , Minhang 200240, Shanghai , China
| | - Zoran Nikoloski
- Max Planck Institute of Molecular Plant Physiology 3 Systems Biology and Mathematical Modelling , , Am Mühlenberg 1, 14476 Potsdam-Golm , Germany
| | - Staffan Persson
- Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University 1 , Minhang 200240, Shanghai , China
- University of Copenhagen 2 Department of Plant and Environmental Sciences (PLEN) , , 1870 Frederiksberg , Denmark
- Copenhagen Plant Science Center (CPSC) 4 , , 1870 Frederiksberg , Denmark
- University of Copenhagen 4 , , 1870 Frederiksberg , Denmark
| | - Dabing Zhang
- Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University 1 , Minhang 200240, Shanghai , China
- School of Agriculture, Food, and Wine 5 , , Waite Campus, Urrbrae, SA 5064 , Australia
- University of Adelaide 5 , , Waite Campus, Urrbrae, SA 5064 , Australia
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15
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Ruan J, Yi P. Exogenous 6-benzylaminopurine inhibits tip growth and cytokinesis via regulating actin dynamics in the moss Physcomitrium patens. PLANTA 2022; 256:1. [PMID: 35616774 DOI: 10.1007/s00425-022-03914-2] [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: 03/03/2022] [Accepted: 05/08/2022] [Indexed: 06/15/2023]
Abstract
Exogenous BAP but not 2iP disrupts actin structures and induces tip-growth retardation and cytokinesis failure in the moss Physcomitrium patens. Synthetic cytokinins have been widely used to address hormonal responses during plant development. However, exogenous cytokinins can cause a variety of cellular effects. A detailed characterization of such effects has not been well studied. Here, using Physcomitrium patens as a model, we show that the aromatic cytokinin 6-benzylaminopurine (BAP) inhibits tip growth at concentrations above 0.2 µM. At higher concentrations (0.6-1 µM), BAP can additionally block mitotic entry and induce cytokinesis defects and cell death. These effects are associated with altered actin dynamics and structures. By contrast, 2-isopentenyladenine (2iP) does not cause marked defects at various concentrations up to 10 µM, while t-zeatin (tZ) can moderately inhibit moss growth. Our results provide mechanistic insight into the inhibitory effects of BAP on cell growth and cell division and call for attention to the use of synthetic cytokinins for bioassays.
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Affiliation(s)
- Jingtong Ruan
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, No. 24 South Section 1, Yihuan Road, Wuhou District, Chengdu, Sichuan, 610065, People's Republic of China
| | - Peishan Yi
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, No. 24 South Section 1, Yihuan Road, Wuhou District, Chengdu, Sichuan, 610065, People's Republic of China.
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16
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Heterologous Expression of Full-Length and Truncated Human ZIP4 Zinc Transporter in Saccharomyces cerevisiae. Biomolecules 2022; 12:biom12050726. [PMID: 35625653 PMCID: PMC9138318 DOI: 10.3390/biom12050726] [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] [Received: 03/22/2022] [Revised: 05/12/2022] [Accepted: 05/13/2022] [Indexed: 02/01/2023] Open
Abstract
The human (h) transporter hZIP4 is the primary Zn2+ importer in the intestine. hZIP4 is also expressed in a variety of organs such as the pancreas and brain. Dysfunction of hZIP4 can result in the Zn2+ deficiency disease acrodermatitis enteropathica (AE). AE can disrupt digestive and immune system homeostasis. A limited number of hZIP4 expression strategies have hindered increasing knowledge about this essential transmembrane protein. Here, we report the heterologous expression of hZIP4 in Saccharomyces cerevisiae. Both a wild-type and a mutant S. cerevisiae strain, in which the endogenous Zn2+ transporters were deleted, were used to test the expression and localization of an hZIP4–GFP fusion protein. A full-length hZIP4–GFP and a truncated membrane-domain-only (mhZIP4–GFP) protein were observed to be present in the plasma membrane in yeast.
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17
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Wasąg P, Suwińska A, Lenartowska M, Lenartowski R. RNAi-Mediated Knockdown of Calreticulin3a Impairs Pollen Tube Growth in Petunia. Int J Mol Sci 2022; 23:ijms23094987. [PMID: 35563382 PMCID: PMC9103332 DOI: 10.3390/ijms23094987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2022] [Revised: 04/14/2022] [Accepted: 04/26/2022] [Indexed: 02/05/2023] Open
Abstract
Pollen tube growth depends on several complex processes, including exo/endocytosis, cell wall biogenesis, intracellular transport, and cell signaling. Our previous results provided evidence that calreticulin (CRT)—a prominent calcium (Ca2+)-buffering molecular chaperone in the endoplasmic reticulum (ER) lumen—is involved in pollen tube formation and function. We previously cloned and characterized the CRT gene belonging to the CRT1/2 subgroup from Petunia hybrida (PhCRT1/2), and found that post-transcriptional silencing of PhCRT1/2 expression strongly impaired pollen tube growth in vitro. Here, we report cloning of a new PhCRT3a homolog; we identified the full-length cDNA sequence and described its molecular characteristics and phylogenetic relationships to other plant CRT3 genes. Using an RNA interference (RNAi) strategy, we found that knockdown of PhCRT3a gene expression caused numerous defects in the morphology and ultrastructure of cultivated pollen tubes, including disorganization of the actin cytoskeleton and loss of cytoplasmic zonation. Elongation of siPhCRT3a pollen tubes was disrupted, and some of them ruptured. Our present data provide the first evidence that PhCRT3a expression is required for normal pollen tube growth. Thus, we discuss relationships between diverse CRT isoforms in several interdependent processes driving the apical growth of the pollen tube, including actomyosin-dependent cytoplasmic streaming, organelle positioning, vesicle trafficking, and cell wall biogenesis.
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Affiliation(s)
- Piotr Wasąg
- Department of Cellular and Molecular Biology, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University in Torun, 87-100 Torun, Poland; (P.W.); (A.S.); (M.L.)
- Department of Biochemistry and Cell Biology, Faculty of Biological Sciences, Kazimierz Wielki University, 85-093 Bydgoszcz, Poland
| | - Anna Suwińska
- Department of Cellular and Molecular Biology, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University in Torun, 87-100 Torun, Poland; (P.W.); (A.S.); (M.L.)
- Centre for Modern Interdisciplinary Technologies, Nicolaus Copernicus University in Torun, 87-100 Torun, Poland
| | - Marta Lenartowska
- Department of Cellular and Molecular Biology, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University in Torun, 87-100 Torun, Poland; (P.W.); (A.S.); (M.L.)
- Centre for Modern Interdisciplinary Technologies, Nicolaus Copernicus University in Torun, 87-100 Torun, Poland
| | - Robert Lenartowski
- Department of Cellular and Molecular Biology, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University in Torun, 87-100 Torun, Poland; (P.W.); (A.S.); (M.L.)
- Centre for Modern Interdisciplinary Technologies, Nicolaus Copernicus University in Torun, 87-100 Torun, Poland
- Correspondence:
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18
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Sing CN, Yang EJ, Swayne TC, Higuchi-Sanabria R, Tsang CA, Boldogh IR, Pon LA. Imaging the Actin Cytoskeleton in Live Budding Yeast Cells. Methods Mol Biol 2022; 2364:53-80. [PMID: 34542848 PMCID: PMC11060504 DOI: 10.1007/978-1-0716-1661-1_3] [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] [Indexed: 04/22/2023]
Abstract
Although budding yeast, Saccharomyces cerevisiae, is widely used as a model organism in biological research, studying cell biology in yeast was hindered due to its small size, rounded morphology, and cell wall. However, with improved techniques, researchers can acquire high-resolution images and carry out rapid multidimensional analysis of a yeast cell. As a result, imaging in yeast has emerged as an important tool to study cytoskeletal organization, function, and dynamics. This chapter describes techniques and approaches for visualizing the actin cytoskeleton in live yeast cells.
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Affiliation(s)
- Cierra N Sing
- Department of Pathology and Cell Biology, Columbia University, College of Physicians and Surgeons, New York, NY, USA
| | - Emily J Yang
- Department of Pathology and Cell Biology, Columbia University, College of Physicians and Surgeons, New York, NY, USA
| | - Theresa C Swayne
- Confocal and Specialized Microscopy Shared Resource, Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, USA
| | - Ryo Higuchi-Sanabria
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA, USA
| | - Catherine A Tsang
- Department of Pathology and Cell Biology, Columbia University, College of Physicians and Surgeons, New York, NY, USA
| | - Istvan R Boldogh
- Department of Pathology and Cell Biology, Columbia University, College of Physicians and Surgeons, New York, NY, USA
- Confocal and Specialized Microscopy Shared Resource, Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, USA
| | - Liza A Pon
- Department of Pathology and Cell Biology, Columbia University, College of Physicians and Surgeons, New York, NY, USA.
- Confocal and Specialized Microscopy Shared Resource, Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, USA.
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19
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Galotto G, Wisanpitayakorn P, Bibeau JP, Liu YC, Furt F, Pierce EC, Simpson PJ, Tüzel E, Vidali L. Myosin XI drives polarized growth by vesicle focusing and local enrichment of F-actin in Physcomitrium patens. PLANT PHYSIOLOGY 2021; 187:2509-2529. [PMID: 34890463 PMCID: PMC8932395 DOI: 10.1093/plphys/kiab435] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 08/13/2021] [Indexed: 05/22/2023]
Abstract
In tip-growing plant cells, growth results from myosin XI and F-actin-mediated deposition of cell wall polysaccharides contained in secretory vesicles. Previous evidence showed that myosin XI anticipates F-actin accumulation at the cell's tip, suggesting a mechanism where vesicle clustering via myosin XI increases F-actin polymerization. To evaluate this model, we used a conditional loss-of-function strategy by generating moss (Physcomitrium patens) plants harboring a myosin XI temperature-sensitive allele. We found that loss of myosin XI function alters tip cell morphology, vacuolar homeostasis, and cell viability but not following F-actin depolymerization. Importantly, our conditional loss-of-function analysis shows that myosin XI focuses and directs vesicles at the tip of the cell, which induces formin-dependent F-actin polymerization, increasing F-actin's local concentration. Our findings support the role of myosin XI in vesicle focusing, possibly via clustering and F-actin organization, necessary for tip growth, and deepen our understanding of additional myosin XI functions.
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Affiliation(s)
- Giulia Galotto
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, Massachusetts 01609, USA
| | | | - Jeffrey P Bibeau
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, Massachusetts 01609, USA
| | - Yen-Chun Liu
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, Massachusetts 01609, USA
| | - Fabienne Furt
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, Massachusetts 01609, USA
| | - Ellen C Pierce
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, Massachusetts 01609, USA
| | - Parker J Simpson
- Bioinformatics and Computational Biology Program, Worcester Polytechnic Institute, Worcester, Massachusetts 01609, USA
| | - Erkan Tüzel
- Bioengineering Department, Temple University, Philadelphia, Pennsylvania 19122, USA
| | - Luis Vidali
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, Massachusetts 01609, USA
- Bioinformatics and Computational Biology Program, Worcester Polytechnic Institute, Worcester, Massachusetts 01609, USA
- Author for communication:
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20
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Xu R, Du S. Overexpression of Lifeact-GFP Disrupts F-Actin Organization in Cardiomyocytes and Impairs Cardiac Function. Front Cell Dev Biol 2021; 9:746818. [PMID: 34765602 PMCID: PMC8576398 DOI: 10.3389/fcell.2021.746818] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Accepted: 10/07/2021] [Indexed: 11/28/2022] Open
Abstract
Lifeact-GFP is a frequently used molecular probe to study F-actin structure and dynamic assembly in living cells. In this study, we generated transgenic zebrafish models expressing Lifeact-GFP specifically in cardiac muscles to investigate the effect of Lifeact-GFP on heart development and its application to study cardiomyopathy. The data showed that transgenic zebrafish with low to moderate levels of Lifeact-GFP expression could be used as a good model to study contractile dynamics of actin filaments in cardiac muscles in vivo. Using this model, we demonstrated that loss of Smyd1b, a lysine methyltransferase, disrupted F-actin filament organization in cardiomyocytes of zebrafish embryos. Our studies, however, also demonstrated that strong Lifeact-GFP expression in cardiomyocytes was detrimental to actin filament organization in cardiomyocytes that led to pericardial edema and early embryonic lethality of zebrafish embryos. Collectively, these data suggest that although Lifeact-GFP is a good probe for visualizing F-actin dynamics, transgenic models need to be carefully evaluated to avoid artifacts induced by Lifeact-GFP overexpression.
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Affiliation(s)
- Rui Xu
- Department of Biochemistry and Molecular Biology, Institute of Marine and Environmental Technology, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Shaojun Du
- Department of Biochemistry and Molecular Biology, Institute of Marine and Environmental Technology, University of Maryland School of Medicine, Baltimore, MD, United States
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21
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Bibeau JP, Galotto G, Wu M, Tüzel E, Vidali L. Quantitative cell biology of tip growth in moss. PLANT MOLECULAR BIOLOGY 2021; 107:227-244. [PMID: 33825083 PMCID: PMC8492783 DOI: 10.1007/s11103-021-01147-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 03/25/2021] [Indexed: 05/16/2023]
Abstract
KEY MESSAGE Here we review, from a quantitative point of view, the cell biology of protonemal tip growth in the model moss Physcomitrium patens. We focus on the role of the cytoskeleton, vesicle trafficking, and cell wall mechanics, including reviewing some of the existing mathematical models of tip growth. We provide a primer for existing cell biological tools that can be applied to the future study of tip growth in moss. Polarized cell growth is a ubiquitous process throughout the plant kingdom in which the cell elongates in a self-similar manner. This process is important for nutrient uptake by root hairs, fertilization by pollen, and gametophyte development by the protonemata of bryophytes and ferns. In this review, we will focus on the tip growth of moss cells, emphasizing the role of cytoskeletal organization, cytoplasmic zonation, vesicle trafficking, cell wall composition, and dynamics. We compare some of the existing knowledge on tip growth in protonemata against what is known in pollen tubes and root hairs, which are better-studied tip growing cells. To fully understand how plant cells grow requires that we deepen our knowledge in a variety of forms of plant cell growth. We focus this review on the model plant Physcomitrium patens, which uses tip growth as the dominant form of growth at its protonemal stage. Because mosses and vascular plants shared a common ancestor more than 450 million years ago, we anticipate that both similarities and differences between tip growing plant cells will provide mechanistic information of tip growth as well as of plant cell growth in general. Towards this mechanistic understanding, we will also review some of the existing mathematical models of plant tip growth and their applicability to investigate protonemal morphogenesis. We attempt to integrate the conclusions and data across cell biology and physical modeling to our current state of knowledge of polarized cell growth in P. patens and highlight future directions in the field.
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Affiliation(s)
- Jeffrey P Bibeau
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, MA, USA
| | - Giulia Galotto
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, MA, USA
| | - Min Wu
- Department of Mathematical Sciences, Worcester Polytechnic Institute, Worcester, MA, USA
- Bioinformatics and Computational Biology Program, Worcester Polytechnic Institute, Worcester, MA, USA
| | - Erkan Tüzel
- Bioengineering Department, Temple University, Philadelphia, PA, USA
| | - Luis Vidali
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, MA, USA.
- Bioinformatics and Computational Biology Program, Worcester Polytechnic Institute, Worcester, MA, USA.
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22
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Tian X, Wang X, Li Y. Myosin XI-B is involved in the transport of vesicles and organelles in pollen tubes of Arabidopsis thaliana. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 108:1145-1161. [PMID: 34559914 DOI: 10.1111/tpj.15505] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 09/09/2021] [Accepted: 09/14/2021] [Indexed: 06/13/2023]
Abstract
The movement of organelles and vesicles in pollen tubes depends on F-actin. However, the molecular mechanism through which plant myosin XI drives the movement of organelles is still controversial, and the relationship between myosin XI and vesicle movement in pollen tubes is also unclear. In this study, we found that the siliques of the myosin xi-b/e mutant were obviously shorter than those of the wild-type (WT) and that the seed set of the mutant was severely deficient. The pollen tube growth of myosin xi-b/e was significantly inhibited both in vitro and in vivo. Fluorescence recovery after photobleaching showed that the velocity of vesicle movement in the pollen tube tip of the myosin xi-b/e mutant was lower than that of the WT. It was also found that peroxisome movement was significantly inhibited in the pollen tubes of the myosin xi-b/e mutant, while the velocities of the Golgi stack and mitochondrial movement decreased relatively less in the pollen tubes of the mutant. The endoplasmic reticulum streaming in the pollen tube shanks was not significantly different between the WT and the myosin xi-b/e mutant. In addition, we found that myosin XI-B-GFP colocalized obviously with vesicles and peroxisomes in the pollen tubes of Arabidopsis. Taken together, these results indicate that myosin XI-B may bind mainly to vesicles and peroxisomes, and drive their movement in pollen tubes. These results also suggest that the mechanism by which myosin XI drives organelle movement in plant cells may be evolutionarily conserved compared with other eukaryotic cells.
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Affiliation(s)
- Xiulin Tian
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Xingjuan Wang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Yan Li
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
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23
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Imaging the Cytoskeleton in Living Plant Roots. Methods Mol Biol 2021; 2364:139-148. [PMID: 34542851 DOI: 10.1007/978-1-0716-1661-1_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
Abstract
For the past two decades, genetically encoded fluorescent proteins have emerged as the most popular method to image the plant cytoskeleton. Because fluorescent protein technology involves handling living plant cells, it is important to implement protocols that enable these delicate plant specimens to maintain optimal growth for the entire duration of the imaging experiment. To this end, we rely on a system that consists of a large coverslip coated with nutrient-supplemented agar. This agar-coverslip system is planted with surface-sterilized Arabidopsis thaliana seeds expressing cytoskeletal fluorescent protein reporters. The agar-coverslip system with planted seeds is then maintained in an environmentally controlled growth chamber. The entire setup is transferred onto the stage of a confocal microscope for imaging when roots of germinated seedlings reach a desired length. For plants with larger roots such as Medicago truncatula, the polymerized nutrient-supplemented agar is gently lifted or cut and used to secure pre-germinated seeds on the coverslip prior to root imaging. The agar-coverslip system we use for imaging the cytoskeleton in living roots along with general methods for expressing green fluorescent protein (GFP)-based cytoskeletal reporters in hairy roots of Medicago truncatula is described here.
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24
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Li Y, Deng Z, Kamisugi Y, Chen Z, Wang J, Han X, Wei Y, He H, Terzaghi W, Cove DJ, Cuming AC, Chen H. A minus-end directed kinesin motor directs gravitropism in Physcomitrella patens. Nat Commun 2021; 12:4470. [PMID: 34294690 PMCID: PMC8298521 DOI: 10.1038/s41467-021-24546-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2020] [Accepted: 06/21/2021] [Indexed: 11/22/2022] Open
Abstract
Gravity is a critical environmental factor regulating directional growth and morphogenesis in plants, and gravitropism is the process by which plants perceive and respond to the gravity vector. The cytoskeleton is proposed to play important roles in gravitropism, but the underlying mechanisms are obscure. Here we use genetic screening in Physcomitrella patens, to identify a locus GTRC, that when mutated, reverses the direction of protonemal gravitropism. GTRC encodes a processive minus-end-directed KCHb kinesin, and its N-terminal, C-terminal and motor domains are all essential for transducing the gravity signal. Chimeric analysis between GTRC/KCHb and KCHa reveal a unique role for the N-terminus of GTRC in gravitropism. Further study shows that gravity-triggered normal asymmetric distribution of actin filaments in the tip of protonema is dependent on GTRC. Thus, our work identifies a microtubule-based cellular motor that determines the direction of plant gravitropism via mediating the asymmetric distribution of actin filaments. Gravitropism is the process by which plants perceive and respond to gravity. Here the authors identify a minus-end-directed kinesin required for gravity-triggered actin filament rearrangement and negative gravitropic response in the moss Physcomitrella patens, thus linking a microtubule-based cellular motor to gravitropism via actin.
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Affiliation(s)
- Yufan Li
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences and School of Life Sciences, Peking University, Beijing, China
| | - Zhaoguo Deng
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | | | - Zhiren Chen
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China.,Tsinghua-Peking Center for Life Sciences, Beijing, China
| | - Jiajun Wang
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences and School of Life Sciences, Peking University, Beijing, China
| | - Xue Han
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences and School of Life Sciences, Peking University, Beijing, China
| | - Yuxiao Wei
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences and School of Life Sciences, Peking University, Beijing, China.,Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Hang He
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences and School of Life Sciences, Peking University, Beijing, China
| | | | - David J Cove
- Centre for Plant Sciences, University of Leeds, Leeds, UK
| | | | - Haodong Chen
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China. .,Tsinghua-Peking Center for Life Sciences, Beijing, China.
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25
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Fratini M, Krishnamoorthy P, Stenzel I, Riechmann M, Matzner M, Bacia K, Heilmann M, Heilmann I. Plasma membrane nano-organization specifies phosphoinositide effects on Rho-GTPases and actin dynamics in tobacco pollen tubes. THE PLANT CELL 2021; 33:642-670. [PMID: 33955493 PMCID: PMC8136918 DOI: 10.1093/plcell/koaa035] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Accepted: 11/23/2020] [Indexed: 05/04/2023]
Abstract
Pollen tube growth requires coordination of cytoskeletal dynamics and apical secretion. The regulatory phospholipid phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2) is enriched in the subapical plasma membrane of pollen tubes of Arabidopsis thaliana and tobacco (Nicotiana tabacum) and can influence both actin dynamics and secretion. How alternative PtdIns(4,5)P2 effects are specified is unclear. In tobacco pollen tubes, spinning disc microscopy (SD) reveals dual distribution of a fluorescent PtdIns(4,5)P2-reporter in dynamic plasma membrane nanodomains vs. apparent diffuse membrane labeling, consistent with spatially distinct coexisting pools of PtdIns(4,5)P2. Several PI4P 5-kinases (PIP5Ks) can generate PtdIns(4,5)P2 in pollen tubes. Despite localizing to one membrane region, the PIP5Ks AtPIP5K2-EYFP and NtPIP5K6-EYFP display distinctive overexpression effects on cell morphologies, respectively related to altered actin dynamics or membrane trafficking. When analyzed by SD, AtPIP5K2-EYFP associated with nanodomains, whereas NtPIP5K6-EYFP localized diffusely. Chimeric AtPIP5K2-EYFP and NtPIP5K6-EYFP variants with reciprocally swapped membrane-associating domains evoked reciprocally shifted effects on cell morphology upon overexpression. Overall, active PI4P 5-kinase variants stabilized actin when targeted to nanodomains, suggesting a role of nanodomain-associated PtdIns(4,5)P2 in actin regulation. This notion is further supported by interaction and proximity of nanodomain-associated AtPIP5K2 with the Rho-GTPase NtRac5, and by its functional interplay with elements of Rho of plants signaling. Plasma membrane nano-organization may thus aid the specification of PtdIns(4,5)P2 functions to coordinate cytoskeletal dynamics and secretion.
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Affiliation(s)
- Marta Fratini
- Department of Plant Biochemistry, Institute of Biochemistry and Biotechnology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany
| | - Praveen Krishnamoorthy
- Department of Plant Biochemistry, Institute of Biochemistry and Biotechnology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany
| | - Irene Stenzel
- Department of Plant Biochemistry, Institute of Biochemistry and Biotechnology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany
| | - Mara Riechmann
- Department of Plant Biochemistry, Institute of Biochemistry and Biotechnology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany
| | - Monique Matzner
- Department of Plant Biochemistry, Institute of Biochemistry and Biotechnology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany
| | - Kirsten Bacia
- Department of Biophysical Chemistry, Institute of Chemistry, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany
| | - Mareike Heilmann
- Department of Plant Biochemistry, Institute of Biochemistry and Biotechnology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany
| | - Ingo Heilmann
- Department of Plant Biochemistry, Institute of Biochemistry and Biotechnology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany
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26
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Abstract
The plant cell wall is an extracellular matrix that envelopes cells, gives them structure and shape, constitutes the interface with symbionts, and defends plants against external biotic and abiotic stress factors. The assembly of this matrix is regulated and mediated by the cytoskeleton. Cytoskeletal elements define where new cell wall material is added and how fibrillar macromolecules are oriented in the wall. Inversely, the cytoskeleton is also key in the perception of mechanical cues generated by structural changes in the cell wall as well as the mediation of intracellular responses. We review the delivery processes of the cell wall precursors that are required for the cell wall assembly process and the structural continuity between the inside and the outside of the cell. We provide an overview of the different morphogenetic processes for which cell wall assembly is a crucial element and elaborate on relevant feedback mechanisms.
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Guan L, Yang S, Li S, Liu Y, Liu Y, Yang Y, Qin G, Wang H, Wu T, Wang Z, Feng X, Wu Y, Zhu JK, Li X, Li L. AtSEC22 Regulates Cell Morphogenesis via Affecting Cytoskeleton Organization and Stabilities. FRONTIERS IN PLANT SCIENCE 2021; 12:635732. [PMID: 34149743 PMCID: PMC8211912 DOI: 10.3389/fpls.2021.635732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 04/01/2021] [Indexed: 05/03/2023]
Abstract
The plant cytoskeleton forms a stereoscopic network that regulates cell morphogenesis. The cytoskeleton also provides tracks for trafficking of vesicles to the target membrane. Fusion of vesicles with the target membrane is promoted by SNARE proteins, etc. The vesicle-SNARE, Sec22, regulates membrane trafficking between the ER and Golgi in yeast and mammals. Arabidopsis AtSEC22 might also regulate early secretion and is essential for gametophyte development. However, the role of AtSEC22 in plant development is unclear. To clarify the role of AtSEC22 in the regulation of plant development, we isolated an AtSEC22 knock-down mutant, atsec22-4, and found that cell morphogenesis and development were seriously disturbed. atsec22-4 exhibited shorter primary roots (PRs), dwarf plants, and partial abortion. More interestingly, the atsec22-4 mutant had less trichomes with altered morphology, irregular stomata, and pavement cells, suggesting that cell morphogenesis was perturbed. Further analyses revealed that in atsec22-4, vesicle trafficking was blocked, resulting in the trapping of proteins in the ER and collapse of structures of the ER and Golgi apparatus. Furthermore, AtSEC22 defects resulted in impaired organization and stability of the cytoskeleton in atsec22-4. Our findings revealed essential roles of AtSEC22 in membrane trafficking and cytoskeleton dynamics during plant development.
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Affiliation(s)
- Li Guan
- Key Laboratory of Saline-Alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Sciences, Northeast Forestry University, Harbin, China
| | - Shurui Yang
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai’an, China
| | - Shenglin Li
- Key Laboratory of Saline-Alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Sciences, Northeast Forestry University, Harbin, China
| | - Yu Liu
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai’an, China
| | - Yuqi Liu
- Key Laboratory of Saline-Alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Sciences, Northeast Forestry University, Harbin, China
| | - Yi Yang
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai’an, China
| | - Guochen Qin
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Haihai Wang
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Tao Wu
- Key Laboratory of Soybean Molecular Design Breeding, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun, China
| | - Zhigang Wang
- School of Life Sciences and Agriculture and Forestry, Qiqihar University, Qiqihar, China
| | - Xianzhong Feng
- Key Laboratory of Soybean Molecular Design Breeding, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun, China
| | - Yongrui Wu
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Jian-Kang Zhu
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Xugang Li
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai’an, China
| | - Lixin Li
- Key Laboratory of Saline-Alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Sciences, Northeast Forestry University, Harbin, China
- *Correspondence: Lixin Li,
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28
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Xu Y, Huang S. Control of the Actin Cytoskeleton Within Apical and Subapical Regions of Pollen Tubes. Front Cell Dev Biol 2020; 8:614821. [PMID: 33344460 PMCID: PMC7744591 DOI: 10.3389/fcell.2020.614821] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 11/13/2020] [Indexed: 01/07/2023] Open
Abstract
In flowering plants, sexual reproduction involves a double fertilization event, which is facilitated by the delivery of two non-motile sperm cells to the ovule by the pollen tube. Pollen tube growth occurs exclusively at the tip and is extremely rapid. It strictly depends on an intact actin cytoskeleton, and is therefore an excellent model for uncovering the molecular mechanisms underlying dynamic actin cytoskeleton remodeling. There has been a long-term debate about the organization and dynamics of actin filaments within the apical and subapical regions of pollen tube tips. By combining state-of-the-art live-cell imaging with the usage of mutants which lack different actin-binding proteins, our understanding of the origin, spatial organization, dynamics and regulation of actin filaments within the pollen tube tip has greatly improved. In this review article, we will summarize the progress made in this area.
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Affiliation(s)
| | - Shanjin Huang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
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Wang X, Sheng X, Tian X, Zhang Y, Li Y. Organelle movement and apical accumulation of secretory vesicles in pollen tubes of Arabidopsis thaliana depend on class XI myosins. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 104:1685-1697. [PMID: 33067901 DOI: 10.1111/tpj.15030] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 09/12/2020] [Accepted: 09/18/2020] [Indexed: 06/11/2023]
Abstract
F-actin and myosin XI play important roles in plant organelle movement. A few myosin XI genes in the genome of Arabidopsis are mainly expressed in mature pollen, which suggests that they may play a crucial role in pollen germination and pollen tube tip growth. In this study, a genetic complementation assay was conducted in a myosin xi-c (myo11c1) myosin xi-e (myo11c2) double mutant, and fluorescence labeling combined with microscopic observation was applied. We found that myosin XI-E (Myo11C2)-green fluorescent protein (GFP) restored the slow pollen tube growth and seed deficiency phenotypes of the myo11c1 myo11c2 double mutant and Myo11C2-GFP partially colocalized with mitochondria, peroxisomes and Golgi stacks. Furthermore, decreased mitochondrial movement and subapical accumulation were detected in myo11c1 myo11c2 double mutant pollen tubes. Fluorescence recovery after photobleaching experiments showed that the fluorescence recoveries of GFP-RabA4d and AtPRK1-GFP at the pollen tube tip of the myo11c1 myo11c2 double mutant were lower than those of the wild type were after photobleaching. These results suggest that Myo11C2 may be associated with mitochondria, peroxisomes and Golgi stacks, and play a crucial role in organelle movement and apical accumulation of secretory vesicles in pollen tubes of Arabidopsis thaliana.
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Affiliation(s)
- Xingjuan Wang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Xiaojing Sheng
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Xiulin Tian
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Yu Zhang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Yan Li
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
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30
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Liu HK, Li YJ, Wang SJ, Yuan TL, Huang WJ, Dong X, Pei JQ, Zhang D, McCormick S, Tang WH. Kinase Partner Protein Plays a Key Role in Controlling the Speed and Shape of Pollen Tube Growth in Tomato. PLANT PHYSIOLOGY 2020; 184:1853-1869. [PMID: 33020251 PMCID: PMC7723124 DOI: 10.1104/pp.20.01081] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Accepted: 09/23/2020] [Indexed: 05/10/2023]
Abstract
The rapid and responsive growth of a pollen tube requires delicate coordination of membrane receptor signaling, Rho-of-Plants (ROP) GTPase activity switching, and actin cytoskeleton assembly. The tomato (Solanum lycopersicum) kinase partner protein (KPP), is a ROP guanine nucleotide exchange factor (GEF) that activates ROP GTPases and interacts with the tomato pollen receptor kinases LePRK1 and LePRK2. It remains unclear how KPP relays signals from plasma membrane-localized LePRKs to ROP switches and other cellular machineries to modulate pollen tube growth. Here, we biochemically verified KPP's activity on ROP4 and showed that KPP RNA interference transgenic pollen tubes grew slower while KPP-overexpressing pollen tubes grew faster, suggesting that KPP functions as a rheostat for speed control in LePRK2-mediated pollen tube growth. The N terminus of KPP is required for self-inhibition of its ROPGEF activity, and expression of truncated KPP lacking the N terminus caused pollen tube tip enlargement. The C-terminus of KPP is required for its interaction with LePRK1 and LePRK2, and the expression of a truncated KPP lacking the C-terminus triggered pollen tube bifurcation. Furthermore, coexpression assays showed that self-associated KPP recruited actin-nucleating Actin-Related Protein2/3 (ARP2/3) complexes to the tip membrane. Interfering with ARP2/3 activity reduced the pollen tube abnormalities caused by overexpressing KPP fragments. In conclusion, KPP plays a key role in pollen tube speed and shape control by recruiting the branched actin nucleator ARP2/3 complex and an actin bundler to the membrane-localized receptors LePRK1 and LePRK2.
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Affiliation(s)
- Hai-Kuan Liu
- National Key Laboratory of Plant Molecular Genetics, Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yu-Jie Li
- National Key Laboratory of Plant Molecular Genetics, Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shu-Jie Wang
- National Key Laboratory of Plant Molecular Genetics, Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ting-Lu Yuan
- National Key Laboratory of Plant Molecular Genetics, Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wei-Jie Huang
- National Key Laboratory of Plant Molecular Genetics, Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xin Dong
- National Key Laboratory of Plant Molecular Genetics, Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jia-Qi Pei
- National Key Laboratory of Plant Molecular Genetics, Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Dong Zhang
- National Key Laboratory of Plant Molecular Genetics, Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Sheila McCormick
- Plant Gene Expression Center, United States Department of Agriculture/Agricultural Research Service, and Department of Plant and Microbial Biology, University of California at Berkeley, Albany, California 94710
| | - Wei-Hua Tang
- National Key Laboratory of Plant Molecular Genetics, Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
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31
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Grebnev G, Cvitkovic M, Fritz C, Cai G, Smith AS, Kost B. Quantitative Structural Organization of Bulk Apical Membrane Traffic in Pollen Tubes. PLANT PHYSIOLOGY 2020; 183:1559-1585. [PMID: 32482906 PMCID: PMC7401101 DOI: 10.1104/pp.20.00380] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 05/15/2020] [Indexed: 05/13/2023]
Abstract
Pollen tube tip growth depends on balancing secretion of cell wall material with endocytic recycling of excess material incorporated into the plasma membrane (PM). The classical model of tip growth, which predicts bulk secretion, occurs apically, and is compensated by subapical endocytosis, has been challenged in recent years. Many signaling proteins and lipids with important functions in the regulation of membrane traffic underlying tip growth associate with distinct regions of the pollen tube PM, and understanding the mechanisms responsible for the targeting of these regulatory factors to specific PM domains requires quantitative information concerning the sites of bulk secretion and endocytosis. Here, we quantitatively characterized the spatial organization of membrane traffic during tip growth by analyzing steady-state distributions and dynamics of FM4-64-labeled lipids and YFP-tagged transmembrane (TM) proteins in tobacco (Nicotiana tabacum) pollen tubes growing normally or treated with Brefeldin A to block secretion. We established that (1) secretion delivers TM proteins and recycled membrane lipids to the same apical PM domain, and (2) FM4-64-labeled lipids, but not the analyzed TM proteins, undergo endocytic recycling within a clearly defined subapical region. We mathematically modeled the steady-state PM distributions of all analyzed markers to better understand differences between them and to support the experimental data. Finally, we mapped subapical F-actin fringe and trans-Golgi network positioning relative to sites of bulk secretion and endocytosis to further characterize functions of these structures in apical membrane traffic. Our results support and further define the classical model of apical membrane traffic at the tip of elongating pollen tubes.
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Affiliation(s)
- Gleb Grebnev
- Cell Biology, Department of Biology, Friedrich-Alexander-University Erlangen Nuremberg, 91058 Erlangen, Germany
| | - Mislav Cvitkovic
- PULS Group, Department of Physics, Friedrich-Alexander-University Erlangen Nuremberg, 91058 Erlangen, Germany
- Group for Computational Life Sciences, Division of Physical Chemistry, Ruđer Bošković Institute, 10000 Zagreb, Croatia
| | - Carolin Fritz
- Cell Biology, Department of Biology, Friedrich-Alexander-University Erlangen Nuremberg, 91058 Erlangen, Germany
| | - Giampiero Cai
- Department of Life Sciences, University of Siena, 53100 Siena, Italy
| | - Ana-Suncana Smith
- PULS Group, Department of Physics, Friedrich-Alexander-University Erlangen Nuremberg, 91058 Erlangen, Germany
- Group for Computational Life Sciences, Division of Physical Chemistry, Ruđer Bošković Institute, 10000 Zagreb, Croatia
| | - Benedikt Kost
- Cell Biology, Department of Biology, Friedrich-Alexander-University Erlangen Nuremberg, 91058 Erlangen, Germany
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32
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Galotto G, Abreu I, Sherman C, Liu B, Gonzalez-Guerrero M, Vidali L. Chitin Triggers Calcium-Mediated Immune Response in the Plant Model Physcomitrella patens. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2020; 33:911-920. [PMID: 32240064 DOI: 10.1094/mpmi-03-20-0064-r] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
A characteristic feature of a plant immune response is the increase of the cytosolic calcium (Ca2+) concentration following infection, which results in the downstream activation of immune response regulators. The bryophyte Physcomitrella patens has been shown to mount an immune response when exposed to bacteria, fungi, or chitin elicitation, in a manner similar to the one observed in Arabidopsis thaliana. Nevertheless, whether the response of P. patens to microorganism exposure is Ca2+ mediated is currently unknown. Here, we show that P. patens plants treated with chitin oligosaccharides exhibit Ca2+ oscillations, and that a calcium ionophore can stimulate the expression of defense-related genes. Treatment with chitin oligosaccharides also results in an inhibition of growth, which can be explained by the depolymerization of the apical actin cytoskeleton of tip growing cells. These results suggest that chitin-triggered calcium oscillations are conserved and were likely present in the common ancestor of bryophytes and vascular plants.
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Affiliation(s)
- Giulia Galotto
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, MA, U.S.A
| | - Isidro Abreu
- Centro de Biotecnología y Genómica de Plantas (UPM-INIA), Universidad Politécnica de Madrid, Madrid, Spain
| | - Catherine Sherman
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, MA, U.S.A
- Bioinformatics and Computational Biology Program, Worcester Polytechnic Institute, Worcester, MA, U.S.A
| | - Boyuan Liu
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, MA, U.S.A
| | - Manuel Gonzalez-Guerrero
- Centro de Biotecnología y Genómica de Plantas (UPM-INIA), Universidad Politécnica de Madrid, Madrid, Spain
- Department of Biotechnology-Plant Biology, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid, Madrid, Spain
| | - Luis Vidali
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, MA, U.S.A
- Bioinformatics and Computational Biology Program, Worcester Polytechnic Institute, Worcester, MA, U.S.A
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33
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Domozych DS, Sun L, Palacio-Lopez K, Reed R, Jeon S, Li M, Jiao C, Sørensen I, Fei Z, Rose JKC. Endomembrane architecture and dynamics during secretion of the extracellular matrix of the unicellular charophyte, Penium margaritaceum. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:3323-3339. [PMID: 31974570 PMCID: PMC7289721 DOI: 10.1093/jxb/eraa039] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 01/21/2020] [Indexed: 05/02/2023]
Abstract
The extracellular matrix (ECM) of many charophytes, the assemblage of green algae that are the sister group to land plants, is complex, produced in large amounts, and has multiple essential functions. An extensive secretory apparatus and endomembrane system are presumably needed to synthesize and secrete the ECM, but structural details of such a system have not been fully characterized. Penium margaritaceum is a valuable unicellular model charophyte for studying secretion dynamics. We report that Penium has a highly organized endomembrane system, consisting of 150-200 non-mobile Golgi bodies that process and package ECM components into different sets of vesicles that traffic to the cortical cytoplasm, where they are transported around the cell by cytoplasmic streaming. At either fixed or transient areas, specific cytoplasmic vesicles fuse with the plasma membrane and secrete their constituents. Extracellular polysaccharide (EPS) production was observed to occur in one location of the Golgi body and sometimes in unique Golgi hybrids. Treatment of cells with brefeldin A caused disruption of the Golgi body, and inhibition of EPS secretion and cell wall expansion. The structure of the endomembrane system in Penium provides mechanistic insights into how extant charophytes generate large quantities of ECM, which in their ancestors facilitated the colonization of land.
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Affiliation(s)
- David S Domozych
- Department of Biology, Skidmore College, Saratoga Springs, NY, USA
- Correspondence:
| | - Li Sun
- Department of Biology, Skidmore College, Saratoga Springs, NY, USA
| | | | - Reagan Reed
- Department of Biology, Skidmore College, Saratoga Springs, NY, USA
| | - Susan Jeon
- Department of Biology, Skidmore College, Saratoga Springs, NY, USA
| | - Mingjia Li
- Department of Biology, Skidmore College, Saratoga Springs, NY, USA
| | - Chen Jiao
- Boyce Thompson Institute, Ithaca, NY, USA
| | - Iben Sørensen
- Plant Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, USA
| | - Zhangjun Fei
- Boyce Thompson Institute, Ithaca, NY, USA
- U.S. Department of Agriculture-Agricultural Research Service, Robert W. Holley Center for Agriculture and Health, Ithaca, NY, USA
| | - Jocelyn K C Rose
- Plant Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, USA
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34
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Kimata Y, Ueda M. Intracellular dynamics and transcriptional regulations in plant zygotes: a case study of Arabidopsis. PLANT REPRODUCTION 2020; 33:89-96. [PMID: 32322957 DOI: 10.1007/s00497-020-00389-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 04/09/2020] [Indexed: 06/11/2023]
Abstract
Recent understandings ofArabidopsiszygote. Body axis formation is essential for the proper development of multicellular organisms. The apical-basal axis in Arabidopsis thaliana is determined by the asymmetric division of the zygote, following its cellular polarization. However, the regulatory mechanism of zygote polarization is unclear due to technical issues. The zygote is located deep in the seed (ovule) in flowers, which prevents the living dynamics of zygotes from being observed. In addition, elucidation of molecular pathways by conventional forward genetic screens was not enough because of high gene redundancy in early development. Here, we present a review introducing two new methods, which have been developed to overcome these problems. Method 1: the two-photon live-cell imaging method provides a new system to visualize the dynamics of intracellular structures in Arabidopsis zygotes, such as cytoskeletons and vacuoles. Microtubules form transverse rings and control zygote elongation, while vacuoles dynamically change their shapes along longitudinal actin filaments and support polar nuclear migration. Method 2: the transcriptome method uses isolated Arabidopsis zygotes and egg cells to reveal the gene expression profiles before and after fertilization. This approach revealed that de novo transcription occurs extensively and immediately after fertilization. Moreover, inhibition of the de novo transcription was shown to sufficiently block the zygotic division, thus indicating a strong possibility that yet unidentified zygote regulators can be found using this transcriptome approach. These new strategies in Arabidopsis will help to further our understanding of the fundamental principles regarding the proper formation of plant bodies from unicellular zygotes.
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Affiliation(s)
- Yusuke Kimata
- Institute of Transformative Bio-Molecules (ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8601, Japan
| | - Minako Ueda
- Institute of Transformative Bio-Molecules (ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8601, Japan.
- Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8602, Japan.
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35
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Rho of Plants GTPases and Cytoskeletal Elements Control Nuclear Positioning and Asymmetric Cell Division during Physcomitrella patens Branching. Curr Biol 2020; 30:2860-2868.e3. [PMID: 32470363 DOI: 10.1016/j.cub.2020.05.022] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 04/06/2020] [Accepted: 05/06/2020] [Indexed: 02/02/2023]
Abstract
Branching morphogenesis is a widely used mechanism for development [1, 2]. In plants, it is initiated by the emergence of a new growth axis, which is of particular importance for plants to explore space and access resources [1]. Branches can emerge either from a single cell or from a group of cells [3-5]. In both cases, the mother cells that initiate branching must undergo dynamic morphological changes and/or adopt oriented asymmetric cell divisions (ACDs) to establish the new growth direction. However, the underlying mechanisms are not fully understood. Here, using the bryophyte moss Physcomitrella patens as a model, we show that side-branch formation in P. patens protonemata requires coordinated polarized cell expansion, directional nuclear migration, and orientated ACD. By combining pharmacological experiments, long-term time-lapse imaging, and genetic analyses, we demonstrate that Rho of plants (ROP) GTPases and actin are essential for cell polarization and local cell expansion (bulging). The growing bulge acts as a prerequisite signal to guide long-distance microtubule (MT)-dependent nuclear migration, which determines the asymmetric positioning of the division plane. MTs play an essential role in nuclear migration but are less involved in bulge formation. Hence, cell polarity and cytoskeletal elements act cooperatively to modulate cell morphology and nuclear positioning during branch initiation. We propose that polarity-triggered nuclear positioning and ACD comprise a fundamental mechanism for increasing multicellularity and tissue complexity during plant morphogenesis.
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36
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Rensing SA, Goffinet B, Meyberg R, Wu SZ, Bezanilla M. The Moss Physcomitrium ( Physcomitrella) patens: A Model Organism for Non-Seed Plants. THE PLANT CELL 2020; 32:1361-1376. [PMID: 32152187 PMCID: PMC7203925 DOI: 10.1105/tpc.19.00828] [Citation(s) in RCA: 137] [Impact Index Per Article: 34.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 02/17/2020] [Accepted: 03/05/2020] [Indexed: 05/06/2023]
Abstract
Since the discovery two decades ago that transgenes are efficiently integrated into the genome of Physcomitrella patens by homologous recombination, this moss has been a premier model system to study evolutionary developmental biology questions, stem cell reprogramming, and the biology of nonvascular plants. P patens was the first non-seed plant to have its genome sequenced. With this level of genomic information, together with increasing molecular genetic tools, a large number of reverse genetic studies have propelled the use of this model system. A number of technological advances have recently opened the door to forward genetics as well as extremely efficient and precise genome editing in P patens Additionally, careful phylogenetic studies with increased resolution have suggested that P patens emerged from within Physcomitrium Thus, rather than Physcomitrella patens, the species should be named Physcomitrium patens Here we review these advances and describe the areas where P patens has had the most impact on plant biology.
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Affiliation(s)
- Stefan A Rensing
- Faculty of Biology, Plant Cell Biology, Philipps University of Marburg, 35037 Marburg an der Lahn, Hesse, Germany
| | - Bernard Goffinet
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut 06269
| | - Rabea Meyberg
- Faculty of Biology, Plant Cell Biology, Philipps University of Marburg, 35037 Marburg an der Lahn, Hesse, Germany
| | - Shu-Zon Wu
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire 03755
| | - Magdalena Bezanilla
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire 03755
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37
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Galotto G, Bibeau JP, Vidali L. Automated Image Acquisition and Morphological Analysis of Cell Growth Mutants in Physcomitrella patens. Methods Mol Biol 2020; 1992:307-322. [PMID: 31148047 DOI: 10.1007/978-1-4939-9469-4_20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/05/2023]
Abstract
This protocol describes the automated imaging and a quantitative analysis of the morphology of small plants from the moss Physcomitrella patens. This method can be used for the analysis of growth phenotypes produced by transient RNA interference or for the analysis of stable mutant plants. Furthermore, we describe how to acquire higher resolution images via the acquisition of a collection of multiple overlapping tiles from the same image. Information is presented to guide the investigator in the choice of vectors and basic conditions to perform transient RNA interference in moss. Detailed directions and examples for fluorescence image acquisition of small regenerating moss plants are provided. Instructions for stitching image tiles and for using an ImageJ-based macro for the quantitative morphological analysis of moss plants are also provided.
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Affiliation(s)
- Giulia Galotto
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, MA, USA
| | - Jeffrey P Bibeau
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, MA, USA
| | - Luis Vidali
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, MA, USA.
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Bibeau JP, Furt F, Mousavi SI, Kingsley JL, Levine MF, Tüzel E, Vidali L. In vivo interactions between myosin XI, vesicles and filamentous actin are fast and transient in Physcomitrella patens. J Cell Sci 2020; 133:jcs.234682. [PMID: 31964706 DOI: 10.1242/jcs.234682] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 01/07/2020] [Indexed: 12/25/2022] Open
Abstract
The actin cytoskeleton and active membrane trafficking machinery are essential for polarized cell growth. To understand the interactions between myosin XI, vesicles and actin filaments in vivo, we performed fluorescence recovery after photobleaching and showed that the dynamics of myosin XIa at the tip of the spreading earthmoss Physcomitrella patens caulonemal cells are actin-dependent and that 50% of myosin XI is bound to vesicles. To obtain single-particle information, we used variable-angle epifluorescence microscopy in protoplasts to demonstrate that protein myosin XIa and VAMP72-labeled vesicles localize in time and space over periods lasting only a few seconds. By tracking data with Hidden Markov modeling, we showed that myosin XIa and VAMP72-labeled vesicles exhibit short runs of actin-dependent directed transport. We also found that the interaction of myosin XI with vesicles is short-lived. Together, this vesicle-bound fraction, fast off-rate and short average distance traveled seem be crucial for the dynamic oscillations observed at the tip, and might be vital for regulation and recycling of the exocytosis machinery, while simultaneously promoting vesicle focusing and vesicle secretion at the tip, necessary for cell wall expansion.
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Affiliation(s)
- Jeffrey P Bibeau
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, MA 01609, USA
| | - Fabienne Furt
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, MA 01609, USA
| | - S Iman Mousavi
- Department of Physics, Worcester Polytechnic Institute, Worcester, MA 01609, USA
| | - James L Kingsley
- Department of Physics, Worcester Polytechnic Institute, Worcester, MA 01609, USA
| | - Max F Levine
- Bioinformatics and Computational Biology Program, Worcester Polytechnic Institute, Worcester, MA 01609, USA
| | - Erkan Tüzel
- Department of Physics, Worcester Polytechnic Institute, Worcester, MA 01609, USA.,Bioinformatics and Computational Biology Program, Worcester Polytechnic Institute, Worcester, MA 01609, USA.,Bioengineering Department, College of Engineering, Temple University, Philadelphia, PA 19122, USA
| | - Luis Vidali
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, MA 01609, USA .,Bioinformatics and Computational Biology Program, Worcester Polytechnic Institute, Worcester, MA 01609, USA
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van Gisbergen P, Wu SZ, Cheng X, Pattavina KA, Bezanilla M. In vivo analysis of formin dynamics in the moss P. patens reveals functional class diversification. J Cell Sci 2020; 133:jcs233791. [PMID: 31969472 PMCID: PMC10679510 DOI: 10.1242/jcs.233791] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 01/07/2020] [Indexed: 01/02/2023] Open
Abstract
Formins are actin regulators critical for diverse processes across eukaryotes. With many formins in plants and animals, it has been challenging to determine formin function in vivo We found that the phylogenetically distinct class I integral membrane formins (denoted For1) from the moss P.patens enrich at sites of membrane turnover, with For1D more tightly associated with the plasma membrane than For1A. To probe formin function, we generated formin-null lines with greatly reduced formin complexity. We found that For1A and For1D help to anchor actin near the cell apex, with For1A contributing to formation of cytosolic actin, while For1D contributes to plasma membrane-associated actin. At the cortex, For1A and For1D localized to motile puncta and differentially impacted actin dynamics. We found that class I cortical formin mobility depended on microtubules and only moderately on actin, whereas class II formin (denoted For2) mobility solely depended on actin. Moreover, cortical For2A tightly correlated with the puncta labeled by the endocytic membrane dye FM4-64, and null mutants in class I formins did not affect uptake of a similar dye, FM1-43, suggesting that class I and II formins are involved in distinct membrane trafficking pathways.
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Affiliation(s)
- Peter van Gisbergen
- Plant Biology Graduate Program, University of Massachusetts, Amherst, MA 01003, USA
| | - Shu-Zon Wu
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA
| | - Xiaohang Cheng
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA
| | - Kelli A Pattavina
- Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, MA 01003, USA
| | - Magdalena Bezanilla
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA
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de Bang L, Paez-Garcia A, Cannon AE, Chin S, Kolape J, Liao F, Sparks JA, Jiang Q, Blancaflor EB. Brassinosteroids Inhibit Autotropic Root Straightening by Modifying Filamentous-Actin Organization and Dynamics. FRONTIERS IN PLANT SCIENCE 2020; 11:5. [PMID: 32117357 PMCID: PMC7010715 DOI: 10.3389/fpls.2020.00005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Accepted: 01/06/2020] [Indexed: 05/12/2023]
Abstract
When positioned horizontally, roots grow down toward the direction of gravity. This phenomenon, called gravitropism, is influenced by most of the major plant hormones including brassinosteroids. Epi-brassinolide (eBL) was previously shown to enhance root gravitropism, a phenomenon similar to the response of roots exposed to the actin inhibitor, latrunculin B (LatB). This led us to hypothesize that eBL might enhance root gravitropism through its effects on filamentous-actin (F-actin). This hypothesis was tested by comparing gravitropic responses of maize (Zea mays) roots treated with eBL or LatB. LatB- and eBL-treated roots displayed similar enhanced downward growth compared with controls when vertical roots were oriented horizontally. Moreover, the effects of the two compounds on root growth directionality were more striking on a slowly-rotating two-dimensional clinostat. Both compounds inhibited autotropism, a process in which the root straightened after the initial gravistimulus was withdrawn by clinorotation. Although eBL reduced F-actin density in chemically-fixed Z. mays roots, the impact was not as strong as that of LatB. Modification of F-actin organization after treatment with both compounds was also observed in living roots of barrel medic (Medicago truncatula) seedlings expressing genetically encoded F-actin reporters. Like in fixed Z. mays roots, eBL effects on F-actin in living M. truncatula roots were modest compared with those of LatB. Furthermore, live cell imaging revealed a decrease in global F-actin dynamics in hypocotyls of etiolated M. truncatula seedlings treated with eBL compared to controls. Collectively, our data indicate that eBL-and LatB-induced enhancement of root gravitropism can be explained by inhibited autotropic root straightening, and that eBL affects this process, in part, by modifying F-actin organization and dynamics.
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Affiliation(s)
- Louise de Bang
- Noble Research Institute LLC, Ardmore, OK, United States
- Department of Plant and Environmental Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Ashley E. Cannon
- Noble Research Institute LLC, Ardmore, OK, United States
- Department of Biological Sciences, University of North Texas, Denton, TX, United States
| | - Sabrina Chin
- Noble Research Institute LLC, Ardmore, OK, United States
| | - Jaydeep Kolape
- Noble Research Institute LLC, Ardmore, OK, United States
- Center for Biotechnology, University of Nebraska—Lincoln, Lincoln, NE, United States
| | - Fuqi Liao
- Noble Research Institute LLC, Ardmore, OK, United States
| | - J. Alan Sparks
- Noble Research Institute LLC, Ardmore, OK, United States
| | - Qingzhen Jiang
- Noble Research Institute LLC, Ardmore, OK, United States
| | - Elison B. Blancaflor
- Noble Research Institute LLC, Ardmore, OK, United States
- *Correspondence: Elison B. Blancaflor,
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41
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Rathgeb U, Chen M, Buron F, Feddermann N, Schorderet M, Raisin A, Häberli GY, Marc-Martin S, Keller J, Delaux PM, Schaefer DG, Reinhardt D. VAPYRIN-like is required for development of the moss Physcomitrella patens. Development 2020; 147:dev.184762. [DOI: 10.1242/dev.184762] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 04/19/2020] [Indexed: 12/28/2022]
Abstract
The VAPYRIN (VPY) gene in Medicago truncatula and Petunia hybrida is required for arbuscular mycorrhizal (AM) symbiosis. The moss Physcomitrella patens has a close homologue (VPY-like, VPYL), although it does not form AM. Here, we explore the phylogeny of VPY and VPYL in land plants, and we study the expression and developmental function of VPYL in P. patens. We show that PpVPYL is expressed primarily in the protonema, the early filamentous stage of moss development, and later in rhizoids arising from the leafy gametophores and in adult phyllids. Knockout mutants have specific phenotypes in branching of the protonema and in cell division of the leaves (phyllids) in gametophores. The mutants are responsive to auxin and strigolactone, which are involved in the regulation of protonemal branching, indicating that the mutants are not affected in hormonal signaling. Taken together, these results suggest that PpVPYL exerts negative regulation of protonemal branching and of cell division in phyllids. We discuss VPY and VPYL phylogeny and function in land plants in the context of AM symbiosis in angiosperms, and of development in the moss.
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Affiliation(s)
- Ursina Rathgeb
- Dept. of Biology, University of Fribourg, Fribourg, Switzerland
| | - Min Chen
- Dept. of Biology, University of Fribourg, Fribourg, Switzerland
| | - Flavien Buron
- Dept. of Biology, University of Fribourg, Fribourg, Switzerland
| | | | | | - Axelle Raisin
- Dept. of Biology, University of Fribourg, Fribourg, Switzerland
| | | | | | - Jean Keller
- Laboratoire de Recherche en Sciences Végétales, Université de Toulouse, CNRS, Auzeville, Castanet-Tolosan, France
| | - Pierre-Marc Delaux
- Laboratoire de Recherche en Sciences Végétales, Université de Toulouse, CNRS, Auzeville, Castanet-Tolosan, France
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Jia H, Chen S, Wang X, Shi C, Liu K, Zhang S, Li J. Copper oxide nanoparticles alter cellular morphology via disturbing the actin cytoskeleton dynamics in Arabidopsis roots. Nanotoxicology 2019; 14:127-144. [PMID: 31684790 DOI: 10.1080/17435390.2019.1678693] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Copper oxide nanoparticles (CuO NPs) have severe nano-toxic effects on organisms. Limited data is available on influence of CuO NPs on plant cells. Here, the molecular mechanisms involved in the toxicity of CuO NPs are studied. Exposure to CuO NPs significantly increased copper content in roots (0.062-0.325 mg/g FW), but CuO NPs translocation rates from root to shoot were low (1.1-2.8%). Presented data were significant at p < 0.05 compared to control. CuO NPs inhibited longitudinal growth and promoted transverse growth in root tip cells. However, CuO NPs did not affect the leaf cells, implying that the transfer ability of CuO NPs was weak, and toxicity mainly affected roots. CuO NPs can conjugate with actin protein. The actin cytoskeleton experienced reorganization in the presence of CuO NPs. The longitudinal filamentous actin (F-actin) decreased, and the transverse F-actin increased. CuO NPs inhibited actin polymerization and promoted depolymerization. The behavior of individual F-actin was at steady state with time-lapse under CuO NPs treatment by time-lapse reflection fluorescence (TIRF) microscopy. The growth rate of actin filaments was weakened by CuO NPs. CuO NPs disturbed the subcellular localization of PINs and the gradient of auxin distribution in root tips in an actin-dependent manner. In conclusion, CuO NPs conjugated with actin and disturbed F-actin dynamics, triggering abnormal cell growth in the root tip, and findings provide theoretical basis for further study nano-toxicity in plants.
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Affiliation(s)
- Honglei Jia
- Biomass Energy Center for Arid and Semi-Arid Lands, College of Life Sciences, Northwest a&F University, Yangling, Shaanxi, China.,School of Environmental Science and Engineering, Shaanxi University of Science and Technology, Xi'an, Shaanxi, China
| | - Sisi Chen
- Biomass Energy Center for Arid and Semi-Arid Lands, College of Life Sciences, Northwest a&F University, Yangling, Shaanxi, China
| | - Xiaofeng Wang
- Biomass Energy Center for Arid and Semi-Arid Lands, College of Life Sciences, Northwest a&F University, Yangling, Shaanxi, China
| | - Cong Shi
- Biomass Energy Center for Arid and Semi-Arid Lands, College of Life Sciences, Northwest a&F University, Yangling, Shaanxi, China
| | - Kena Liu
- School of Environmental Science and Engineering, Shaanxi University of Science and Technology, Xi'an, Shaanxi, China
| | - Shuangxi Zhang
- Biomass Energy Center for Arid and Semi-Arid Lands, College of Life Sciences, Northwest a&F University, Yangling, Shaanxi, China
| | - Jisheng Li
- Biomass Energy Center for Arid and Semi-Arid Lands, College of Life Sciences, Northwest a&F University, Yangling, Shaanxi, China
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Chang J, Xu Z, Li M, Yang M, Qin H, Yang J, Wu S. Spatiotemporal cytoskeleton organizations determine morphogenesis of multicellular trichomes in tomato. PLoS Genet 2019; 15:e1008438. [PMID: 31584936 PMCID: PMC6812842 DOI: 10.1371/journal.pgen.1008438] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 10/24/2019] [Accepted: 09/19/2019] [Indexed: 11/18/2022] Open
Abstract
Plant trichomes originate from epidermal cell, forming protective structure from abiotic and biotic stresses. Different from the unicellular trichome in Arabidopsis, tomato trichomes are multicellular structure and can be classified into seven different types based on cell number, shape and the presence of glandular cells. Despite the importance of tomato trichomes in insect resistance, our understanding of the tomato trichome morphogenesis remains elusive. In this study, we quantitatively analyzed morphological traits of trichomes in tomato and further performed live imaging of cytoskeletons in stably transformed lines with actin and microtubule markers. At different developmental stages, two types of cytoskeletons exhibited distinct patterns in different trichome cells, ranging from transverse, spiral to longitudinal. This gradual transition of actin filament angle from basal to top cells could correlate with the spatial expansion mode in different cells. Further genetic screen for aberrant trichome morphology led to the discovery of a number of independent mutations in SCAR/WAVE and ARP2/3 complex, which resulted in actin bundling and distorted trichomes. Disruption of microtubules caused isotropic expansion while abolished actin filaments entirely inhibited axial extension of trichomes, indicating that microtubules and actin filaments may control distinct aspects of trichome cell expansion. Our results shed light on the roles of cytoskeletons in the formation of multicellular structure of tomato trichomes.
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Affiliation(s)
- Jiang Chang
- College of Horticulture, FAFU-UCR Joint Center and Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Zhijing Xu
- College of Horticulture, FAFU-UCR Joint Center and Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Meng Li
- College of Horticulture, FAFU-UCR Joint Center and Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Meina Yang
- College of Horticulture, FAFU-UCR Joint Center and Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Haiyang Qin
- College of Horticulture, FAFU-UCR Joint Center and Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Jie Yang
- College of Horticulture, FAFU-UCR Joint Center and Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Shuang Wu
- College of Horticulture, FAFU-UCR Joint Center and Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Fujian Agriculture and Forestry University, Fuzhou, China
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44
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Reshetniak S, Rizzoli SO. Interrogating Synaptic Architecture: Approaches for Labeling Organelles and Cytoskeleton Components. Front Synaptic Neurosci 2019; 11:23. [PMID: 31507402 PMCID: PMC6716447 DOI: 10.3389/fnsyn.2019.00023] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 08/02/2019] [Indexed: 01/06/2023] Open
Abstract
Synaptic transmission has been studied for decades, as a fundamental step in brain function. The structure of the synapse, and its changes during activity, turned out to be key aspects not only in the transfer of information between neurons, but also in cognitive processes such as learning and memory. The overall synaptic morphology has traditionally been studied by electron microscopy, which enables the visualization of synaptic structure in great detail. The changes in the organization of easily identified structures, such as the presynaptic active zone, or the postsynaptic density, are optimally studied via electron microscopy. However, few reliable methods are available for labeling individual organelles or protein complexes in electron microscopy. For such targets one typically relies either on combination of electron and fluorescence microscopy, or on super-resolution fluorescence microscopy. This review focuses on approaches and techniques used to specifically reveal synaptic organelles and protein complexes, such as cytoskeletal assemblies. We place the strongest emphasis on methods detecting the targets of interest by affinity binding, and we discuss the advantages and limitations of each method.
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Affiliation(s)
- Sofiia Reshetniak
- Institute for Neuro- and Sensory Physiology, Center for Biostructural Imaging of Neurodegeneration (BIN), University Medical Center Göttingen, Göttingen, Germany
- International Max Planck Research School for Molecular Biology, Göttingen, Germany
| | - Silvio O. Rizzoli
- Institute for Neuro- and Sensory Physiology, Center for Biostructural Imaging of Neurodegeneration (BIN), University Medical Center Göttingen, Göttingen, Germany
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Diao M, Li X, Huang S. Arabidopsis AIP1-1 regulates the organization of apical actin filaments by promoting their turnover in pollen tubes. SCIENCE CHINA-LIFE SCIENCES 2019; 63:239-250. [PMID: 31240522 DOI: 10.1007/s11427-019-9532-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 04/02/2019] [Indexed: 11/24/2022]
Abstract
Apical actin filaments are highly dynamic structures that are crucial for rapid pollen tube growth, but the mechanisms regulating their dynamics and spatial organization remain incompletely understood. We here identify that AtAIP1-1 is important for regulating the turnover and organization of apical actin filaments in pollen tubes. AtAIP1-1 is distributed uniformly in the pollen tube and loss of function of AtAIP1-1 affects the organization of the actin cytoskeleton in the pollen tube. Specifically, actin filaments became disorganized within the apical region of aip1-1 pollen tubes. Consistent with the role of apical actin filaments in spatially restricting vesicles in pollen tubes, the apical region occupied by vesicles becomes enlarged in aip1-1 pollen tubes compared to WT. Using ADF1 as a representative actin-depolymerizing factor, we demonstrate that AtAIP1-1 enhances ADF1-mediated actin depolymerization and filament severing in vitro, although AtAIP1-1 alone does not have an obvious effect on actin assembly and disassembly. The dynamics of apical actin filaments are reduced in aip1-1 pollen tubes compared to WT. Our study suggests that AtAIP1-1 works together with ADF to act as a module in regulating the dynamics of apical actin filaments to facilitate the construction of the unique "apical actin structure" in the pollen tube.
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Affiliation(s)
- Min Diao
- Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
- iHuman Institute, Shanghai Tech University, Shanghai, 201210, China
| | - Xin Li
- Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Shanjin Huang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China.
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Mechanism of CAP1-mediated apical actin polymerization in pollen tubes. Proc Natl Acad Sci U S A 2019; 116:12084-12093. [PMID: 31123151 DOI: 10.1073/pnas.1821639116] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Srv2p/CAP1 is an essential regulator of actin turnover, but its exact function in regulating actin polymerization, particularly the contribution of its actin nucleotide exchange activity, remains incompletely understood. We found that, although Arabidopsis CAP1 is distributed uniformly in the cytoplasm, its loss of function has differential effects on the actin cytoskeleton within different regions of the pollen tube. Specifically, the F-actin level increases in the shank but decreases in the apical region of cap1 pollen tubes. The reduction in apical F-actin results mainly from impaired polymerization of membrane-originated actin within cap1 pollen tubes. The actin nucleotide exchange activity of CAP1 is involved in apical actin polymerization. CAP1 acts synergistically with pollen ADF and profilin to promote actin turnover in vitro, and it can overcome the inhibitory effects of ADF and synergize with profilin to promote actin nucleotide exchange. Consistent with its role as a shuttle molecule between ADF and profilin, the cytosolic concentration of CAP1 is much lower than that of ADF and profilin in pollen. Thus, CAP1 synergizes with ADF and profilin to drive actin turnover in pollen and promote apical actin polymerization in pollen tubes in a manner that involves its actin nucleotide exchange activity.
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Laggoun F, Dardelle F, Dehors J, Falconet D, Driouich A, Rochais C, Dallemagne P, Lehner A, Mollet JC. A chemical screen identifies two novel small compounds that alter Arabidopsis thaliana pollen tube growth. BMC PLANT BIOLOGY 2019; 19:152. [PMID: 31010418 PMCID: PMC6475968 DOI: 10.1186/s12870-019-1743-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 03/27/2019] [Indexed: 05/23/2023]
Abstract
BACKGROUND During sexual reproduction, pollen grains land on the stigma, rehydrate and produce pollen tubes that grow through the female transmitting-tract tissue allowing the delivery of the two sperm cells to the ovule and the production of healthy seeds. Because pollen tubes are single cells that expand by tip-polarized growth, they represent a good model to study the growth dynamics, cell wall deposition and intracellular machineries. Aiming to understand this complex machinery, we used a low throughput chemical screen approach in order to isolate new tip-growth disruptors. The effect of a chemical inhibitor of monogalactosyldiacylglycerol synthases, galvestine-1, was also investigated. The present work further characterizes their effects on the tip-growth and intracellular dynamics of pollen tubes. RESULTS Two small compounds among 258 were isolated based on their abilities to perturb pollen tube growth. They were found to disrupt in vitro pollen tube growth of tobacco, tomato and Arabidopsis thaliana. We show that these 3 compounds induced abnormal phenotypes (bulging and/or enlarged pollen tubes) and reduced pollen tube length in a dose dependent manner. Pollen germination was significantly reduced after treatment with the two compounds isolated from the screen. They also affected cell wall material deposition in pollen tubes. The compounds decreased anion superoxide accumulation, disorganized actin filaments and RIC4 dynamics suggesting that they may affect vesicular trafficking at the pollen tube tip. CONCLUSION These molecules may alter directly or indirectly ROP1 activity, a key regulator of pollen tube growth and vesicular trafficking and therefore represent good tools to further study cellular dynamics during polarized-cell growth.
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Affiliation(s)
- Ferdousse Laggoun
- Normandie Université, UNIROUEN, Laboratoire Glycobiologie et Matrice Extracellulaire Végétale EA4358, Fédération de Recherche “NORVEGE”- FED 4277, 76000 Rouen, France
| | - Flavien Dardelle
- Normandie Université, UNIROUEN, Laboratoire Glycobiologie et Matrice Extracellulaire Végétale EA4358, Fédération de Recherche “NORVEGE”- FED 4277, 76000 Rouen, France
- Present Address: LPS-BioSciences, Bâtiment 409, Université Paris-Sud, 91400 Orsay, France
| | - Jérémy Dehors
- Normandie Université, UNIROUEN, Laboratoire Glycobiologie et Matrice Extracellulaire Végétale EA4358, Fédération de Recherche “NORVEGE”- FED 4277, 76000 Rouen, France
| | - Denis Falconet
- Laboratoire de Physiologie Cellulaire et Végétale, CNRS, CEA, INRA, Université Grenoble Alpes, Institut de Biosciences et Biotechnologies de Grenoble, CEA Grenoble, 38000 Grenoble, cedex 9 France
| | - Azeddine Driouich
- Normandie Université, UNIROUEN, Laboratoire Glycobiologie et Matrice Extracellulaire Végétale EA4358, Fédération de Recherche “NORVEGE”- FED 4277, 76000 Rouen, France
| | - Christophe Rochais
- Normandie Université, UNICAEN, Centre d’Etudes et de Recherche sur le Médicament de Normandie, CNRS 3038 INC3M, SFR ICORE, 14032, Caen, France
| | - Patrick Dallemagne
- Normandie Université, UNICAEN, Centre d’Etudes et de Recherche sur le Médicament de Normandie, CNRS 3038 INC3M, SFR ICORE, 14032, Caen, France
| | - Arnaud Lehner
- Normandie Université, UNIROUEN, Laboratoire Glycobiologie et Matrice Extracellulaire Végétale EA4358, Fédération de Recherche “NORVEGE”- FED 4277, 76000 Rouen, France
| | - Jean-Claude Mollet
- Normandie Université, UNIROUEN, Laboratoire Glycobiologie et Matrice Extracellulaire Végétale EA4358, Fédération de Recherche “NORVEGE”- FED 4277, 76000 Rouen, France
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Abstract
Fluorescence recovery after photobleaching (FRAP) is an important tool used by cell biologists to study the diffusion and binding kinetics of vesicles, proteins, and other molecules in the cytoplasm, nucleus, or cell membrane. Although many FRAP models have been developed over the past decades, the influence of the complex boundaries of 3D cellular geometries on the recovery curves, in conjunction with regions of interest and optical effects (imaging, photobleaching, photoswitching, and scanning), has not been well studied. Here, we developed a 3D computational model of the FRAP process that incorporates particle diffusion, cell boundary effects, and the optical properties of the scanning confocal microscope, and validated this model using the tip-growing cells of Physcomitrella patens. We then show how these cell boundary and optical effects confound the interpretation of FRAP recovery curves, including the number of dynamic states of a given fluorophore, in a wide range of cellular geometries-both in two and three dimensions-namely nuclei, filopodia, and lamellipodia of mammalian cells, and in cell types such as the budding yeast, Saccharomyces pombe, and tip-growing plant cells. We explored the performance of existing analytical and algorithmic FRAP models in these various cellular geometries, and determined that the VCell VirtualFRAP tool provides the best accuracy to measure diffusion coefficients. Our computational model is not limited only to these cells types, but can easily be extended to other cellular geometries via the graphical Java-based application we also provide. This particle-based simulation-called the Digital Confocal Microscopy Suite or DCMS-can also perform fluorescence dynamics assays, such as number and brightness, fluorescence correlation spectroscopy, and raster image correlation spectroscopy, and could help shape the way these techniques are interpreted.
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49
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Bascom C, Burkart GM, Mallett DR, O’Sullivan JE, Tomaszewski AJ, Walsh K, Bezanilla M. Systematic survey of the function of ROP regulators and effectors during tip growth in the moss Physcomitrella patens. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:447-457. [PMID: 30380098 PMCID: PMC6322563 DOI: 10.1093/jxb/ery376] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Accepted: 10/18/2018] [Indexed: 05/03/2023]
Abstract
Rho/Rac of plants (ROP) GTPases are plant-specific small GTPases that regulate cell morphology. ROP activity is controlled by several families of regulatory proteins. However, how these diverse regulators contribute to polarized growth remains understudied. In a system-wide approach, we used RNAi to silence each gene family of known ROP regulators in the juvenile tissues of the moss Physcomitrella patens. We found that the GTPase activating proteins, but not the ROP enhancers, are essential for tip growth. The guanine exchange factors (GEFs), which are comprised of ROPGEFs and Spikes, both contribute to growth. However, silencing Spikes results in less-polarized plants as compared to silencing ROPGEFs, suggesting that Spikes contribute more to establishing cell polarity. Silencing the single-gene family of guanine dissociation inhibitors also inhibits growth, resulting in small, unpolarized plants. In contrast, silencing the ROP effector ROP-interactive CRIB-containing (RIC) protein, which is encoded by a single gene, results in plants larger than the controls, suggesting that RIC functions to inhibit tip growth in moss. Taken together, this systematic loss-of-function survey provides insights into the function of ROP regulators during polarized growth.
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Affiliation(s)
- Carlisle Bascom
- Plant Biology Graduate Program, University of Massachusetts, Amherst, USA
- Department of Biological Sciences, Dartmouth College, Hanover NH, USA
| | - Graham M Burkart
- Plant Biology Graduate Program, University of Massachusetts, Amherst, USA
| | - Darren R Mallett
- Department of Biological Sciences, Dartmouth College, Hanover NH, USA
- Biology Department, University of Massachusetts, Amherst, USA
| | | | | | - Katherine Walsh
- Biology Department, University of Massachusetts, Amherst, USA
| | - Magdalena Bezanilla
- Department of Biological Sciences, Dartmouth College, Hanover NH, USA
- Correspondence:
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Zhang S, Wang C, Xie M, Liu J, Kong Z, Su H. Actin Bundles in The Pollen Tube. Int J Mol Sci 2018; 19:ijms19123710. [PMID: 30469514 PMCID: PMC6321563 DOI: 10.3390/ijms19123710] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Revised: 11/18/2018] [Accepted: 11/19/2018] [Indexed: 12/31/2022] Open
Abstract
The angiosperm pollen tube delivers two sperm cells into the embryo sac through a unique growth strategy, named tip growth, to accomplish fertilization. A great deal of experiments have demonstrated that actin bundles play a pivotal role in pollen tube tip growth. There are two distinct actin bundle populations in pollen tubes: the long, rather thick actin bundles in the shank and the short, highly dynamic bundles near the apex. With the development of imaging techniques over the last decade, great breakthroughs have been made in understanding the function of actin bundles in pollen tubes, especially short subapical actin bundles. Here, we tried to draw an overall picture of the architecture, functions and underlying regulation mechanism of actin bundles in plant pollen tubes.
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Affiliation(s)
- Shujuan Zhang
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education College of Life Science, Northwest University, Xi'an 710069, China.
| | - Chunbo Wang
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education College of Life Science, Northwest University, Xi'an 710069, China.
| | - Min Xie
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education College of Life Science, Northwest University, Xi'an 710069, China.
| | - Jinyu Liu
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education College of Life Science, Northwest University, Xi'an 710069, China.
| | - Zhe Kong
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education College of Life Science, Northwest University, Xi'an 710069, China.
| | - Hui Su
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education College of Life Science, Northwest University, Xi'an 710069, China.
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