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Boscq S, Billoud B, Charrier B. Cell-Autonomous and Non-Cell-Autonomous Mechanisms Concomitantly Regulate the Early Developmental Pattern in the Kelp Saccharina latissima Embryo. PLANTS (BASEL, SWITZERLAND) 2024; 13:1341. [PMID: 38794413 PMCID: PMC11125204 DOI: 10.3390/plants13101341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2024] [Revised: 05/08/2024] [Accepted: 05/09/2024] [Indexed: 05/26/2024]
Abstract
Brown algae are multicellular organisms that have evolved independently from plants and animals. Knowledge of the mechanisms involved in their embryogenesis is available only for the Fucus, Dictyota, and Ectocarpus, which are brown algae belonging to three different orders. Here, we address the control of cell growth and cell division orientation in the embryo of Saccharina latissima, a brown alga belonging to the order Laminariales, which grows as a stack of cells through transverse cell divisions until growth is initiated along the perpendicular axis. Using laser ablation, we show that apical and basal cells have different functions in the embryogenesis of this alga, with the apical cell being involved mainly in growth and basal cells controlling the orientation of cell division by inhibiting longitudinal cell division and thereby the widening of the embryo. These functions were observed in the very early development before the embryo reached the 8-cell stage. In addition, the growth of the apical and basal regions appears to be cell-autonomous, because there was no compensation for the loss of a significant part of the embryo upon laser ablation, resulting in smaller and less elongated embryos compared with intact embryos. In contrast, the orientation of cell division in the apical region of the embryo appears to be controlled by the basal cell only, which suggests a polarised, non-cell-autonomous mechanism. Altogether, our results shed light on the early mechanisms of growth rate and growth orientation at the onset of the embryogenesis of Saccharina, in which non-cell-specific cell-autonomous and cell-specific non-cell-autonomous processes are involved. This complex control differs from the mechanisms described in the other brown algal embryos, in which the establishment of embryo polarity depends on environmental cues.
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2
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Bogaert KA, Zakka EE, Coelho SM, De Clerck O. Polarization of brown algal zygotes. Semin Cell Dev Biol 2023; 134:90-102. [PMID: 35317961 DOI: 10.1016/j.semcdb.2022.03.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 03/01/2022] [Accepted: 03/03/2022] [Indexed: 11/29/2022]
Abstract
Brown algae are a group of multicellular, heterokont algae that have convergently evolved developmental complexity that rivals that of embryophytes, animals or fungi. Early in development, brown algal zygotes establish a basal and an apical pole, which will become respectively the basal system (holdfast) and the apical system (thallus) of the adult alga. Brown algae are interesting models for understanding the establishment of cell polarity in a broad evolutionary context, because they exhibit a large diversity of life cycles, reproductive strategies and, importantly, their zygotes are produced in large quantities free of parental tissue, with symmetry breaking and asymmetric division taking place in a highly synchronous manner. This review describes the current knowledge about the establishment of the apical-basal axis in the model brown seaweeds Ectocarpus, Dictyota, Fucus and Saccharina, highlighting the advantages and specific interests of each system. Ectocarpus is a genetic model system that allows access to the molecular basis of early development and life-cycle control over apical-basal polarity. The oogamous brown alga Fucus, together with emerging comparative models Dictyota and Saccharina, emphasize the diversity of strategies of symmetry breaking in determining a cell polarity vector in brown algae. A comparison with symmetry-breaking mechanisms in land plants, animals and fungi, reveals that the one-step zygote polarisation of Fucus compares well to Saccharomyces budding and Arabidopsis stomata development, while the two-phased symmetry breaking in the Dictyota zygote compares to Schizosaccharomyces fission, the Caenorhabditis anterior-posterior zygote polarisation and Arabidopsis prolate pollen polarisation. The apical-basal patterning in Saccharina zygotes on the other hand, may be seen as analogous to that of land plants. Overall, brown algae have the potential to bring exciting new information on how a single cell gives rise to an entire complex body plan.
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Affiliation(s)
- Kenny A Bogaert
- Phycology Research Group, Department of Biology, Ghent University, Krijgslaan 281 S8, B-9000 Ghent, Belgium.
| | - Eliane E Zakka
- Phycology Research Group, Department of Biology, Ghent University, Krijgslaan 281 S8, B-9000 Ghent, Belgium
| | - Susana M Coelho
- Department of Algal Development and Evolution, Max Planck Institute for Biology, Tübingen, Germany
| | - Olivier De Clerck
- Phycology Research Group, Department of Biology, Ghent University, Krijgslaan 281 S8, B-9000 Ghent, Belgium
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Clerc T, Boscq S, Attia R, Kaminski Schierle GS, Charrier B, Läubli NF. Cultivation and Imaging of S. latissima Embryo Monolayered Cell Sheets Inside Microfluidic Devices. Bioengineering (Basel) 2022; 9:bioengineering9110718. [PMID: 36421119 PMCID: PMC9687954 DOI: 10.3390/bioengineering9110718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 11/08/2022] [Accepted: 11/17/2022] [Indexed: 11/23/2022] Open
Abstract
The culturing and investigation of individual marine specimens in lab environments is crucial to further our understanding of this highly complex ecosystem. However, the obtained results and their relevance are often limited by a lack of suitable experimental setups enabling controlled specimen growth in a natural environment while allowing for precise monitoring and in-depth observations. In this work, we explore the viability of a microfluidic device for the investigation of the growth of the alga Saccharina latissima to enable high-resolution imaging by confining the samples, which usually grow in 3D, to a single 2D plane. We evaluate the specimen’s health based on various factors such as its growth rate, cell shape, and major developmental steps with regard to the device’s operating parameters and flow conditions before demonstrating its compatibility with state-of-the-art microscopy imaging technologies such as the skeletonisation of the specimen through calcofluor white-based vital staining of its cell contours as well as the immunolocalisation of the specimen’s cell wall. Furthermore, by making use of the on-chip characterisation capabilities, we investigate the influence of altered environmental illuminations on the embryonic development using blue and red light. Finally, live tracking of fluorescent microspheres deposited on the surface of the embryo permits the quantitative characterisation of growth at various locations of the organism.
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Affiliation(s)
- Thomas Clerc
- Morphogenesis of Macroalgae, Laboratory of Integrative Biology of Marine Models, Station Biologique de Roscoff, CNRS, Sorbonne University, 29680 Roscoff, France
| | - Samuel Boscq
- Morphogenesis of Macroalgae, Laboratory of Integrative Biology of Marine Models, Station Biologique de Roscoff, CNRS, Sorbonne University, 29680 Roscoff, France
| | - Rafaele Attia
- Ecology of Marine Plankton, Laboratory of Adaptation and Diversity in the Marine Environment, Station Biologique de Roscoff, CNRS, Sorbonne University, 29680 Roscoff, France
| | - Gabriele S. Kaminski Schierle
- Molecular Neuroscience Group, Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
| | - Bénédicte Charrier
- Morphogenesis of Macroalgae, Laboratory of Integrative Biology of Marine Models, Station Biologique de Roscoff, CNRS, Sorbonne University, 29680 Roscoff, France
- Correspondence: (B.C.); (N.F.L.)
| | - Nino F. Läubli
- Molecular Neuroscience Group, Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
- Correspondence: (B.C.); (N.F.L.)
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The Interplay between Hydrogen Sulfide and Phytohormone Signaling Pathways under Challenging Environments. Int J Mol Sci 2022; 23:ijms23084272. [PMID: 35457090 PMCID: PMC9032328 DOI: 10.3390/ijms23084272] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Revised: 04/08/2022] [Accepted: 04/11/2022] [Indexed: 01/09/2023] Open
Abstract
Hydrogen sulfide (H2S) serves as an important gaseous signaling molecule that is involved in intra- and intercellular signal transduction in plant–environment interactions. In plants, H2S is formed in sulfate/cysteine reduction pathways. The activation of endogenous H2S and its exogenous application has been found to be highly effective in ameliorating a wide variety of stress conditions in plants. The H2S interferes with the cellular redox regulatory network and prevents the degradation of proteins from oxidative stress via post-translational modifications (PTMs). H2S-mediated persulfidation allows the rapid response of proteins in signaling networks to environmental stimuli. In addition, regulatory crosstalk of H2S with other gaseous signals and plant growth regulators enable the activation of multiple signaling cascades that drive cellular adaptation. In this review, we summarize and discuss the current understanding of the molecular mechanisms of H2S-induced cellular adjustments and the interactions between H2S and various signaling pathways in plants, emphasizing the recent progress in our understanding of the effects of H2S on the PTMs of proteins. We also discuss future directions that would advance our understanding of H2S interactions to ultimately mitigate the impacts of environmental stresses in the plants.
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Bogaert KA, Blomme J, Beeckman T, De Clerck O. Auxin's origin: do PILS hold the key? TRENDS IN PLANT SCIENCE 2022; 27:227-236. [PMID: 34716098 DOI: 10.1016/j.tplants.2021.09.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Revised: 08/23/2021] [Accepted: 09/28/2021] [Indexed: 05/12/2023]
Abstract
Auxin is a key regulator of many developmental processes in land plants and plays a strikingly similar role in the phylogenetically distant brown seaweeds. Emerging evidence shows that the PIN and PIN-like (PILS) auxin transporter families have preceded the evolution of the canonical auxin response pathway. A wide conservation of PILS-mediated auxin transport, together with reports of auxin function in unicellular algae, would suggest that auxin function preceded the advent of multicellularity. We find that PIN and PILS transporters form two eukaryotic subfamilies within a larger bacterial family. We argue that future functional characterisation of algal PIN and PILS transporters can shed light on a common origin of an auxin function followed by independent co-option in a multicellular context.
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Affiliation(s)
- Kenny Arthur Bogaert
- Department of Biology, Ghent University, Krijgslaan 281 S8, B-9000 Ghent, Belgium.
| | - Jonas Blomme
- Department of Biology, Ghent University, Krijgslaan 281 S8, B-9000 Ghent, Belgium; Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium; Center for Plant Systems Biology, VIB-UGent, Technologiepark 72, B-9052 Ghent, Belgium
| | - Tom Beeckman
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium; Center for Plant Systems Biology, VIB-UGent, Technologiepark 72, B-9052 Ghent, Belgium
| | - Olivier De Clerck
- Department of Biology, Ghent University, Krijgslaan 281 S8, B-9000 Ghent, Belgium
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Naramoto S, Hata Y, Fujita T, Kyozuka J. The bryophytes Physcomitrium patens and Marchantia polymorpha as model systems for studying evolutionary cell and developmental biology in plants. THE PLANT CELL 2022; 34:228-246. [PMID: 34459922 PMCID: PMC8773975 DOI: 10.1093/plcell/koab218] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 08/25/2021] [Indexed: 05/03/2023]
Abstract
Bryophytes are nonvascular spore-forming plants. Unlike in flowering plants, the gametophyte (haploid) generation of bryophytes dominates the sporophyte (diploid) generation. A comparison of bryophytes with flowering plants allows us to answer some fundamental questions raised in evolutionary cell and developmental biology. The moss Physcomitrium patens was the first bryophyte with a sequenced genome. Many cell and developmental studies have been conducted in this species using gene targeting by homologous recombination. The liverwort Marchantia polymorpha has recently emerged as an excellent model system with low genomic redundancy in most of its regulatory pathways. With the development of molecular genetic tools such as efficient genome editing, both P. patens and M. polymorpha have provided many valuable insights. Here, we review these advances with a special focus on polarity formation at the cell and tissue levels. We examine current knowledge regarding the cellular mechanisms of polarized cell elongation and cell division, including symmetric and asymmetric cell division. We also examine the role of polar auxin transport in mosses and liverworts. Finally, we discuss the future of evolutionary cell and developmental biological studies in plants.
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Affiliation(s)
| | - Yuki Hata
- Graduate School of Life Sciences, Tohoku University, Aoba-ku, Sendai 980-8577, Japan
| | - Tomomichi Fujita
- Department of Biological Sciences, Faculty of Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan
| | - Junko Kyozuka
- Graduate School of Life Sciences, Tohoku University, Aoba-ku, Sendai 980-8577, Japan
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Bowman JL, Flores Sandoval E, Kato H. On the Evolutionary Origins of Land Plant Auxin Biology. Cold Spring Harb Perspect Biol 2021; 13:cshperspect.a040048. [PMID: 33558368 DOI: 10.1101/cshperspect.a040048] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Indole-3-acetic acid, that is, auxin, is a molecule found in a broad phylogenetic distribution of organisms, from bacteria to eukaryotes. In the ancestral land plant auxin was co-opted to be the paramount phytohormone mediating tropic responses and acting as a facilitator of developmental decisions throughout the life cycle. The evolutionary origins of land plant auxin biology genes can now be traced with reasonable clarity. Genes encoding the two enzymes of the land plant auxin biosynthetic pathway arose in the ancestral land plant by a combination of horizontal gene transfer from bacteria and possible neofunctionalization following gene duplication. Components of the auxin transcriptional signaling network have their origins in ancestral alga genes, with gene duplication and neofunctionalization of key domains allowing integration of a portion of the preexisting transcriptional network with auxin. Knowledge of the roles of orthologous genes in extant charophycean algae is lacking, but could illuminate the ancestral functions of both auxin and the co-opted transcriptional network.
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Affiliation(s)
- John L Bowman
- School of Biological Science, Monash University, Melbourne, Victoria 3800, Australia
| | | | - Hirotaka Kato
- Graduate School of Science, Kobe University, Kobe 657-8501, Japan
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8
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Jaeger R, Moody LA. A fundamental developmental transition in Physcomitrium patens is regulated by evolutionarily conserved mechanisms. Evol Dev 2021; 23:123-136. [PMID: 33822471 DOI: 10.1111/ede.12376] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 03/09/2021] [Accepted: 03/11/2021] [Indexed: 01/15/2023]
Abstract
One of the most defining moments in history was the colonization of land by plants approximately 470 million years ago. The transition from water to land was accompanied by significant changes in the plant body plan, from those than resembled filamentous representatives of the charophytes, the sister group to land plants, to those that were morphologically complex and capable of colonizing harsher habitats. The moss Physcomitrium patens (also known as Physcomitrella patens) is an extant representative of the bryophytes, the earliest land plant lineage. The protonema of P. patens emerges from spores from a chloronemal initial cell, which can divide to self-renew to produce filaments of chloronemal cells. A chloronemal initial cell can differentiate into a caulonemal initial cell, which can divide and self-renew to produce filaments of caulonemal cells, which branch extensively and give rise to three-dimensional shoots. The process by which a chloronemal initial cell differentiates into a caulonemal initial cell is tightly regulated by auxin-induced remodeling of the actin cytoskeleton. Studies have revealed that the genetic mechanisms underpinning this transition also regulate tip growth and differentiation in diverse plant taxa. This review summarizes the known cellular and molecular mechanisms underpinning the chloronema to caulonema transition in P. patens.
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Affiliation(s)
- Richard Jaeger
- Department of Plant Sciences, University of Oxford, Oxford, UK
| | - Laura A Moody
- Department of Plant Sciences, University of Oxford, Oxford, UK
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9
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Biswal DP, Panigrahi KCS. Light- and hormone-mediated development in non-flowering plants: An overview. PLANTA 2020; 253:1. [PMID: 33245411 DOI: 10.1007/s00425-020-03501-3] [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: 03/19/2020] [Accepted: 10/21/2020] [Indexed: 06/11/2023]
Abstract
Light, hormones and their interaction regulate different aspects of development in non-flowering plants. They might have played a role in the evolution of different plant groups by conferring specific adaptive evolutionary changes. Plants are sessile organisms. Unlike animals, they lack the opportunity to abandon their habitat in unfavorable conditions. They respond to different environmental cues and adapt accordingly to control their growth and developmental pattern. While phytohormones are known to be internal regulators of plant development, light is a major environmental signal that shapes plant processes. It is plausible that light-hormone crosstalk might have played an important role in plant evolution. But how the crosstalk between light and phytohormone signaling pathways might have shaped the plant evolution is unclear. One of the possible reasons is that flowering plants have been studied extensively in context of plant development, which cannot serve the purpose of evolutionary comparisons. In order to elucidate the role of light, hormone and their crosstalk in the evolutionary adaptation in plant kingdom, one needs to understand various light- and hormone-mediated processes in diverse non-flowering plants. This review is an attempt to outline major light- and phytohormone-mediated responses in non-flowering plant groups such as algae, bryophytes, pteridophytes and gymnosperms.
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Affiliation(s)
- Durga Prasad Biswal
- School of Biological Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar, Odisha, India
- Homi Bhabha National Institute (HBNI), Training School Complex, Anushakti Nagar, Mumbai, 400094, India
| | - Kishore Chandra Sekhar Panigrahi
- School of Biological Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar, Odisha, India.
- Homi Bhabha National Institute (HBNI), Training School Complex, Anushakti Nagar, Mumbai, 400094, India.
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10
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Murúa P, Edrada-Ebel R, Muñoz L, Soldatou S, Legrave N, Müller DG, Patiño DJ, van West P, Küpper FC, Westermeier R, Ebel R, Peters AF. Morphological, genotypic and metabolomic signatures confirm interfamilial hybridization between the ubiquitous kelps Macrocystis (Arthrothamnaceae) and Lessonia (Lessoniaceae). Sci Rep 2020; 10:8279. [PMID: 32427928 PMCID: PMC7237481 DOI: 10.1038/s41598-020-65137-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2019] [Accepted: 04/28/2020] [Indexed: 01/20/2023] Open
Abstract
Macrocystis pyrifera and Lessonia spicata are economically and ecologically relevant brown seaweeds that recently have been classified as members of two separated families within Laminariales (kelps). Here we describe for the first time the Macrocystis pyrifera x Lessonia spicata hybridization in the wild (Chiloe Island, Southeastern Pacific), where populations of the two parents exist sympatrically. Externally, this hybrid exhibited typical features of its parents M. pyrifera (cylindrical and flexible distal stipes, serrate frond margins and presence of sporophylls) and L. spicata (rigid and flat main stipe and first bifurcation), as well as intermediate features between them (thick unfused haptera in the holdfast). Histological sections revealed the prevalence of mucilage ducts within stipes and fronds (absent in Lessonia) and fully developed unilocular sporangia in the sporophylls. Molecular analyses confirmed the presence of the two parental genotypes for ITS1 nrDNA and the M. pyrifera genotype for two predominantly maternally inherited cytoplasmic markers (COI and rbcLS spacer) in the tissue of the hybrid. A metabolome-wide approach revealed that this hybrid is more chemically reminiscent to M. pyrifera. Nevertheless, several hits were identified as Lessonia exclusive or more remarkably, not present in any of the parent. Meiospores developed into apparently fertile gametophytes, which gave rise to F1 sporophytes that reached several millimeters before suddenly dying. In-vitro reciprocal crossing of Mar Brava gametophytes from both species revealed that although it is rare, interfamilial hybridization between the two species is possible but mostly overcome by pseudogamy of female gametophytes.
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Affiliation(s)
- Pedro Murúa
- Instituto de Acuicultura, Universidad Austral de Chile, Sede Puerto Montt, PO box 1327, Puerto Montt, Chile.
- The Scottish Association for Marine Science, Scottish Marine Institute, Culture Collection for Algae and Protozoa, Oban, Argyll, PA37 1QA, Scotland, United Kingdom.
- Aberdeen Oomycete Group, College of Life Sciences and Medicine, University of Aberdeen, Foresterhill, AB25 2ZD, Aberdeen, United Kingdom.
| | - RuAngelie Edrada-Ebel
- The Natural Products Metabolomics Group, Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, The John Arbuthnott Building, 161 Cathedral Street, Glasgow, G4 0RE, United Kingdom
| | - Liliana Muñoz
- Aberdeen Oomycete Group, College of Life Sciences and Medicine, University of Aberdeen, Foresterhill, AB25 2ZD, Aberdeen, United Kingdom
| | - Sylvia Soldatou
- Marine Biodiscovery Centre, Department of Chemistry, University of Aberdeen, Meston Building, Meston Walk, Old Aberdeen, AB24 3UE, United Kingdom
| | - Nathalie Legrave
- Marine Biodiscovery Centre, Department of Chemistry, University of Aberdeen, Meston Building, Meston Walk, Old Aberdeen, AB24 3UE, United Kingdom
| | - Dieter G Müller
- Fachbereich Biologie der Universität Konstanz, D-78457, Konstanz, Germany
| | - David J Patiño
- Instituto de Acuicultura, Universidad Austral de Chile, Sede Puerto Montt, PO box 1327, Puerto Montt, Chile
| | - Pieter van West
- Aberdeen Oomycete Group, College of Life Sciences and Medicine, University of Aberdeen, Foresterhill, AB25 2ZD, Aberdeen, United Kingdom
| | - Frithjof C Küpper
- Marine Biodiscovery Centre, Department of Chemistry, University of Aberdeen, Meston Building, Meston Walk, Old Aberdeen, AB24 3UE, United Kingdom
- School of Biological Sciences, University of Aberdeen, Cruickshank Building, St Machar Drive, Aberdeen, AB24 3UU, Scotland, UK
| | - Renato Westermeier
- Instituto de Acuicultura, Universidad Austral de Chile, Sede Puerto Montt, PO box 1327, Puerto Montt, Chile
| | - Rainer Ebel
- Marine Biodiscovery Centre, Department of Chemistry, University of Aberdeen, Meston Building, Meston Walk, Old Aberdeen, AB24 3UE, United Kingdom
| | - Akira F Peters
- School of Biological Sciences, University of Aberdeen, Cruickshank Building, St Machar Drive, Aberdeen, AB24 3UU, Scotland, UK
- Bezhin Rosko, 40 rue des pêcheurs, 29250, Santec, Brittany, France
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11
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Abstract
Cell polarity in plants operates across a broad range of spatial and temporal scales to control processes from acute cell growth to systemic hormone distribution. Similar to other eukaryotes, plants generate polarity at both the subcellular and tissue levels, often through polarization of membrane-associated protein complexes. However, likely due to the constraints imposed by the cell wall and their extremely plastic development, plants possess novel polarity molecules and mechanisms highly tuned to environmental inputs. Considerable progress has been made in identifying key plant polarity regulators, but detailed molecular understanding of polarity mechanisms remains incomplete in plants. Here, we emphasize the striking similarities in the conceptual frameworks that generate polarity in both animals and plants. To this end, we highlight how novel, plant-specific proteins engage in common themes of positive feedback, dynamic intracellular trafficking, and posttranslational regulation to establish polarity axes in development. We end with a discussion of how environmental signals control intrinsic polarity to impact postembryonic organogenesis and growth.
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Affiliation(s)
- Andrew Muroyama
- Howard Hughes Medical Institute, Stanford University, Stanford, California 94305-5020, USA; .,Department of Biology, Stanford University, Stanford, California 94305-5020, USA
| | - Dominique Bergmann
- Howard Hughes Medical Institute, Stanford University, Stanford, California 94305-5020, USA; .,Department of Biology, Stanford University, Stanford, California 94305-5020, USA
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12
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Huang JB, Zou Y, Zhang X, Wang M, Dong Q, Tao LZ. RIBOSE PHOSPHATE ISOMERSASE 1 Influences Root Development by Acting on Cell Wall Biosynthesis, Actin Organization, and Auxin Transport in Arabidopsis. FRONTIERS IN PLANT SCIENCE 2020; 10:1641. [PMID: 31969892 PMCID: PMC6960261 DOI: 10.3389/fpls.2019.01641] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 11/21/2019] [Indexed: 05/29/2023]
Abstract
Cell wall biosynthesis plays essential roles in cell division and expansion and thus is fundamental to plant growth and development. In this work, we show that an Arabidopsis mutant dpr3, isolated by a forward genetic screen, displays embryo defects and short, swelling primary root with the failure of maintenance of root apical meristem reminiscent to several cell wall-deficient mutants. Map-based cloning identified dpr3 is a mutant allele of RIBOSE PHOSPHATE ISOMERSASE 1 (RPI1), an enzyme involved in cellulose synthesis. Cellulose content in the mutant was dramatically decreased. Moreover, dpr3 (rpi1 from hereon) caused aberrant auxin distribution, as well as defective accumulation of root master regulators PLETHORA (PLT1 and PLT2) and misexpression of auxin response factor 5 (MONOPTEROS, MP). The abnormal auxin distribution is likely due to the reduced accumulation of auxin efflux transporters PIN-FORMED (PIN1 and PIN3). Surprisingly, we found that the orientation of actin microfilaments was severely altered in rpi1 root cells, whereas the cortical microtubules stay normal. Our study provides evidence that the defects in cellulose synthesis in rpi1 affect polar auxin transport possibly connected with altered F-actin organization, which is critically important for vesicle trafficking, thus exerting effects on auxin distribution, signaling, and auxin-mediated plant development.
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Affiliation(s)
- Jia-Bao Huang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou, China
- State Key Laboratory of Crop Biology, Shandong Agricultural University, Taian, China
| | - Yi Zou
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou, China
| | - Xiaojing Zhang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou, China
| | - Mingyan Wang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou, China
| | - Qingkun Dong
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou, China
| | - Li-Zhen Tao
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou, China
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13
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Bogaert KA, Blommaert L, Ljung K, Beeckman T, De Clerck O. Auxin Function in the Brown Alga Dictyota dichotoma. PLANT PHYSIOLOGY 2019; 179:280-299. [PMID: 30420566 PMCID: PMC6324224 DOI: 10.1104/pp.18.01041] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Accepted: 10/30/2018] [Indexed: 05/14/2023]
Abstract
Auxin controls body plan patterning in land plants and has been proposed to play a similar role in the development of brown algae (Phaeophyta) despite their distant evolutionary relationship with land plants. The mechanism of auxin action in brown algae remains controversial because of contradicting conclusions derived from pharmacological studies on Fucus In this study, we used Dictyota dichotoma as a model system to show that auxin plays a role during the apical-basal patterning of the embryo of brown algae. Indole-3-acetic acid was detectable in D. dichotoma germlings and mature tissue. Although two-celled D. dichotoma zygotes normally develop a rhizoid from one pole and a thallus meristem from the other, addition of exogenous auxins to one-celled embryos affected polarization, and both poles of the spheroidal embryo developed into rhizoids instead. The effect was strongest at lower pH and when variable extrinsic informational cues were applied. 2-[4-(diethylamino)-2-hydroxybenzoyl]benzoic acid, an inhibitor of the ABC-B/multidrug resistance/P-glycoprotein subfamily of transporters in land plants, affected rhizoid formation by increasing rhizoid branching and inducing ectopic rhizoids. An in silico survey of auxin genes suggested that a diverse range of biosynthesis genes and transport genes, such as PIN-LIKES, and the ATP-binding cassette subfamily (ABC-B/multidrug resistance/P-glycoprotein) transporters from land plants have homologs in D. dichotoma and Ectocarpus siliculosus Together with reports on auxin function in basal lineages of green algae, these results suggest that auxin function predates the divergence between the green and brown lineage and the transition toward land plants.
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Affiliation(s)
- Kenny A Bogaert
- Department of Biology, Ghent University, 9000 Ghent, Belgium
| | | | - Karin Ljung
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden
| | - Tom Beeckman
- VIB-UGent Center for Plant Systems Biology, B-9052 Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium
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14
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Linardić M, Braybrook SA. Towards an understanding of spiral patterning in the Sargassum muticum shoot apex. Sci Rep 2017; 7:13887. [PMID: 29066850 PMCID: PMC5654765 DOI: 10.1038/s41598-017-13767-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 09/26/2017] [Indexed: 11/09/2022] Open
Abstract
In plants and parenchymatous brown algae the body arises through the activity of an apical meristem (a niche of cells or a single cell). The meristem produces lateral organs in specific patterns, referred to as phyllotaxis. In plants, two different control mechanisms have been proposed: one is position-dependent and relies on morphogen accumulation at future organ sites; the other is a lineage-based system which links phyllotaxis to the apical cell division pattern. Here we examine the apical patterning of the brown alga, Sargassum muticum, which exhibits spiral phyllotaxis (137.5° angle) and an unlinked apical cell division pattern. The Sargassum apex presents characteristics of a self-organising system, similar to plant meristems. In contrast to complex plant meristems, we were unable to correlate the plant morphogen auxin with bud positioning in Sargassum, nor could we predict cell wall softening at new bud sites. Our data suggests that in Sargassum muticum there is no connection between phyllotaxis and the apical cell division pattern indicating a position-dependent patterning mechanism may be in place. The underlying mechanisms behind the phyllotactic patterning appear to be distinct from those seen in plants.
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Affiliation(s)
- Marina Linardić
- The Sainsbury Laboratory, University of Cambridge, Bateman Street, Cambridge, CB2 1LR, UK
| | - Siobhan A Braybrook
- The Sainsbury Laboratory, University of Cambridge, Bateman Street, Cambridge, CB2 1LR, UK.
- Molecular, Cell and Developmental Biology, UCLA, 610 Charles E Young Dr East, Los Angeles, CA, 90095-7239, USA.
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Ohtaka K, Hori K, Kanno Y, Seo M, Ohta H. Primitive Auxin Response without TIR1 and Aux/IAA in the Charophyte Alga Klebsormidium nitens. PLANT PHYSIOLOGY 2017; 174:1621-1632. [PMID: 28533212 PMCID: PMC5490900 DOI: 10.1104/pp.17.00274] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 05/16/2017] [Indexed: 05/20/2023]
Abstract
The phytohormone auxin regulates many aspects of growth and development in land plants, but the origin and evolution of auxin signaling and response mechanisms remain largely unknown. Indeed, it remains to be investigated whether auxin-related pathways diverged before the emergence of land plants. To address this knowledge deficit, we analyzed auxin responses in the charophyte alga Klebsormidium nitens NIES-2285, whose ancestor diverged from a green algal ancestor during the evolution of land plants. This strain is the same as Klebsormidium flaccidum NIES-2285, for which the draft genome was sequenced in 2014, and was taxonomically reclassified as K. nitens This genome sequence revealed genes involved in auxin responses. Furthermore, the auxin indole-3-acetic acid (IAA) was detected in cultures of K. nitens, but K. nitens lacks the central regulators of the canonical auxin-signaling pathway found in land plants. Exogenous IAA inhibited cell division and cell elongation in K. nitens Inhibitors of auxin biosynthesis and of polar auxin transport also inhibited cell division and elongation. Moreover, exogenous IAA rapidly induced expression of a LATERAL ORGAN BOUNDARIES-DOMAIN transcription factor. These results suggest that K. nitens has acquired the part of the auxin system that regulates transcription and cell growth without the requirement for the central players that govern auxin signaling in land plants.
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Affiliation(s)
- Kinuka Ohtaka
- Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Kanagawa, 226-8503, Japan
| | - Koichi Hori
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Kanagawa, 226-8503, Japan
| | - Yuri Kanno
- RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, 230-0045, Japan
| | - Mitsunori Seo
- RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, 230-0045, Japan
| | - Hiroyuki Ohta
- Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Kanagawa, 226-8503, Japan
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Kanagawa, 226-8503, Japan
- Japan Science and Technology Agency, Core Research for Evolutional Science and Technology Program, Tokyo, 102-0076, Japan
- Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, 152-8550, Japan
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16
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Kovaleva LV, Voronkov AS, Zakharova EV, Minkina YV, Timofeeva GV, Andreev IM. Exogenous IAA and ABA stimulate germination of petunia male gametophyte by activating Ca2+-dependent K+-channels and by modulating the activity of plasmalemma H+-ATPase and actin cytoskeleton. Russ J Dev Biol 2016. [DOI: 10.1134/s1062360416030036] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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17
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Zhu J, Geisler M. Keeping it all together: auxin-actin crosstalk in plant development. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:4983-98. [PMID: 26085676 DOI: 10.1093/jxb/erv308] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Polar auxin transport and the action of the actin cytoskeleton are tightly interconnected, which is documented by the finding that auxin transporters reach their final destination by active movement of secretory vesicles along F-actin tracks. Moreover, auxin transporter polarity and flexibility is thought to depend on transporter cycling that requires endocytosis and exocytosis of vesicles. In this context, we have reviewed the current literature on an involvement of the actin cytoskeleton in polar auxin transport and identify known similarities and differences in its structure, function and dynamics in comparison to non-plant organisms. By describing how auxin modulates actin expression and actin organization and how actin and its stability affects auxin-transporter endocytosis and recycling, we discuss the current knowledge on regulatory auxin-actin feedback loops. We focus on known effects of auxin and of auxin transport inhibitors on the stability and organization of actin and examine the functionality of auxin and/or auxin transport inhibitor-binding proteins with respect to their suitability to integrate auxin/auxin transport inhibitor action. Finally, we indicate current difficulties in the interpretation of organ, time and concentration-dependent auxin/auxin transport inhibitor treatments and formulate simple future experimental guidelines.
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Affiliation(s)
- Jinsheng Zhu
- University of Fribourg, Department of Biology-Plant Biology, CH-1700 Fribourg, Switzerland
| | - Markus Geisler
- University of Fribourg, Department of Biology-Plant Biology, CH-1700 Fribourg, Switzerland
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Jia H, Hu Y, Fan T, Li J. Hydrogen sulfide modulates actin-dependent auxin transport via regulating ABPs results in changing of root development in Arabidopsis. Sci Rep 2015; 5:8251. [PMID: 25652660 PMCID: PMC4317700 DOI: 10.1038/srep08251] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Accepted: 01/12/2015] [Indexed: 01/22/2023] Open
Abstract
Hydrogen sulfide (H2S) signaling has been considered a key regulator of plant developmental processes and defenses. In this study, we demonstrate that high levels of H2S inhibit auxin transport and lead to alterations in root system development. H2S inhibits auxin transport by altering the polar subcellular distribution of PIN proteins. The vesicle trafficking and distribution of the PIN proteins are an actin-dependent process. H2S changes the expression of several actin-binding proteins (ABPs) and decreases the occupancy percentage of F-actin bundles in the Arabidopsis roots. We observed the effects of H2S on F-actin in T-DNA insertion mutants of cpa, cpb and prf3, indicating that the effects of H2S on F-actin are partially removed in the mutant plants. Thus, these data imply that the ABPs act as downstream effectors of the H2S signal and thereby regulate the assembly and depolymerization of F-actin in root cells. Taken together, our data suggest that the existence of a tightly regulated intertwined signaling network between auxin, H2S and actin that controls root system development. In the proposed process, H2S plays an important role in modulating auxin transport by an actin-dependent method, which results in alterations in root development in Arabidopsis.
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Affiliation(s)
- Honglei Jia
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Yanfeng Hu
- Key Laboratory of Mollisols Agroecology, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Nangang District, Harbin 150000, China
| | - Tingting Fan
- School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei, Anhui 230009, China
| | - Jisheng Li
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
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Rice actin-binding protein RMD is a key link in the auxin-actin regulatory loop that controls cell growth. Proc Natl Acad Sci U S A 2014; 111:10377-82. [PMID: 24982173 DOI: 10.1073/pnas.1401680111] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The plant hormone auxin plays a central role in plant growth and development. Auxin transport and signaling depend on actin organization. Despite its functional importance, the mechanistic link between actin filaments (F-actin) and auxin intracellular signaling remains unclear. Here, we report that the actin-organizing protein Rice Morphology Determinant (RMD), a type II formin from rice (Oryza sativa), provides a key link. Mutants lacking RMD display abnormal cell growth and altered configuration of F-actin array direction. The rmd mutants also exhibit an inhibition of auxin-mediated cell elongation, decreased polar auxin transport, altered auxin distribution gradients in root tips, and suppression of plasma membrane localization of auxin transporters O. sativa PIN-FORMED 1b (OsPIN1b) and OsPIN2 in root cells. We demonstrate that RMD is required for endocytosis, exocytosis, and auxin-mediated OsPIN2 recycling to the plasma membrane. Moreover, RMD expression is directly regulated by heterodimerized O. sativa auxin response factor 23 (OsARF23) and OsARF24, providing evidence that auxin modulates the orientation of F-actin arrays through RMD. In support of this regulatory loop, osarf23 and lines with reduced expression of both OsARF23 and OsARF24 display reduced RMD expression, disrupted F-actin organization and cell growth, less sensitivity to auxin response, and altered auxin distribution and OsPIN localization. Our findings establish RMD as a crucial component of the auxin-actin self-organizing regulatory loop from the nucleus to cytoplasm that controls rice cell growth and morphogenesis.
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Vondráková Z, Eliášová K, Vágner M. The anti-actin drugs latrunculin and cytochalasin affect the maturation of spruce somatic embryos in different ways. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2014; 221-222:90-9. [PMID: 24656339 DOI: 10.1016/j.plantsci.2014.02.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Revised: 01/24/2014] [Accepted: 02/19/2014] [Indexed: 05/13/2023]
Abstract
The role of the actin cytoskeleton in somatic embryo development was investigated using latrunculin B and cytochalasin D. Brief treatments (1h) with either drug at the start of maturation fragmented the actin in suspensor cells and/or depolymerized actin filaments in meristematic cells. The drugs targeted different cells: latB primarily affected the suspensor cells, but cchD damaged both suspensor and meristematic cells. Lethal damage to the meristematic and suspensor cells was observed when the drugs were applied throughout the maturation period, although the severity of this effect depended on their concentrations. The drugs' effects on the yield of mature somatic embryos were investigated by applying them to embryo cultures throughout the maturation period or for one week at three different points in the maturation process: immediately prior to the start of maturation, during the first week of maturation, and during the fourth week of maturation. The strongest effects were observed when the drugs were applied at the start of maturation. Under these conditions, latB destroyed the suspensors, eliminating the underdeveloped embryos that depend on them. This accelerated the development of embryos that were capable of separating from the suspensors. Thus, while the total number of embryos at the end of the maturation period was lower than in untreated control cultures, the surviving mature embryos were of high quality. cchD treatment at the start of maturation strongly inhibited embryo development. Drug treatment at the end of the maturation period did not significantly affect embryo development: latB caused no change in the yield of somatic embryos, but cchD treatment increased the number of malformed embryos compared to untreated controls.
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Affiliation(s)
- Zuzana Vondráková
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Rozvojová 263, CZ-16502 Prague 6, Czech Republic
| | - Kateřina Eliášová
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Rozvojová 263, CZ-16502 Prague 6, Czech Republic
| | - Martin Vágner
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Rozvojová 263, CZ-16502 Prague 6, Czech Republic.
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21
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Zhang S, van Duijn B. Cellular Auxin Transport in Algae. PLANTS 2014; 3:58-69. [PMID: 27135491 PMCID: PMC4844313 DOI: 10.3390/plants3010058] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 12/20/2013] [Accepted: 01/14/2014] [Indexed: 12/18/2022]
Abstract
The phytohormone auxin is one of the main directors of plant growth and development. In higher plants, auxin is generated in apical plant parts and transported from cell-to-cell in a polar fashion. Auxin is present in all plant phyla, and the existence of polar auxin transport (PAT) is well established in land plants. Algae are a group of relatively simple, autotrophic, photosynthetic organisms that share many features with land plants. In particular, Charophyceae (a taxon of green algae) are closest ancestors of land plants. In the study of auxin function, transport and its evolution, the algae form an interesting research target. Recently, proof for polar auxin transport in Chara species was published and auxin related research in algae gained more attention. In this review we discuss auxin transport in algae with respect to land plants and suggest directions for future studies.
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Affiliation(s)
- Suyun Zhang
- Plant Biodynamics Laboratory, Biology Institute Leiden, Leiden University, Sylviusweg 72, Leiden 2333, BE, The Netherlands.
| | - Bert van Duijn
- Plant Biodynamics Laboratory, Biology Institute Leiden, Leiden University, Sylviusweg 72, Leiden 2333, BE, The Netherlands.
- Fytagoras, Sylviusweg 72, Leiden 2333, BE, The Netherlands.
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22
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Blancaflor EB. Regulation of plant gravity sensing and signaling by the actin cytoskeleton. AMERICAN JOURNAL OF BOTANY 2013; 100:143-52. [PMID: 23002165 DOI: 10.3732/ajb.1200283] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Gravitropism is a process by which plant organs readjust their growth toward or away from the gravity vector when the plant is reoriented. The actin cytoskeleton has often been a significant component of models explaining gravitropism, but its role in this process has become somewhat controversial in light of reports showing that actin inhibitors enhance the gravitropic response. The work with inhibitors implies that actin might function as a negative regulator of gravitropism. In this article, possibilities for how such a role might be accomplished are presented. First, the organization of actin in statocytes is revisited in an attempt to rationalize how compressive forces exerted by statoliths on membranes can lead to enhanced gravity sensing. Second, recent genetic work in the model plant Arabidopsis thaliana is discussed, focusing on the potential involvement of the protein degradation machinery in actin-mediated control of statolith dynamics and on the intriguing possibility that an actin-regulated, ligand-receptor mechanism for gravity signal transduction might operate in higher plants. Third, modifications in the trafficking of auxin efflux transporters are considered as possible mechanisms for the enhanced gravity responses observed in plant organs when the actin cytoskeleton is disrupted by chemical inhibitors. The various possibilities presented in this review emphasize the large amount of research that remains to be done before we can fully understand how the actin cytoskeleton modulates tropisms in higher plants.
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Affiliation(s)
- Elison B Blancaflor
- Plant Biology Division, The Samuel Roberts Noble Foundation Inc., 2510 Sam Noble Parkway, Ardmore, Oklahoma 73401, USA.
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23
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Abstract
Brown algae are an extremely interesting, but surprisingly poorly explored, group of organisms. They are one of only five eukaryotic lineages to have independently evolved complex multicellularity, which they express through a wide variety of morphologies ranging from uniseriate branched filaments to complex parenchymatous thalli with multiple cell types. Despite their very distinct evolutionary history, brown algae and land plants share a striking amount of developmental features. This has led to an interest in several aspects of brown algal development, including embryogenesis, polarity, cell cycle, asymmetric cell division and a putative role for plant hormone signalling. This review describes how investigations using brown algal models have helped to increase our understanding of the processes controlling early embryo development, in particular polarization, axis formation and asymmetric cell division. Additionally, the diversity of life cycles in the brown lineage and the emergence of Ectocarpus as a powerful model organism, are affording interesting insights on the molecular mechanisms underlying haploid-diploid life cycles. The use of these and other emerging brown algal models will undoubtedly add to our knowledge on the mechanisms that regulate development in multicellular photosynthetic organisms.
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Affiliation(s)
- Kenny A Bogaert
- Phycology Research Group, Department of Biology, Center for Molecular Phylogenetics and Evolution, Ghent University, Ghent, Belgium
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24
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Raven JA. Polar auxin transport in relation to long-distance transport of nutrients in the Charales. JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:1-9. [PMID: 23264638 DOI: 10.1093/jxb/ers358] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
This paper examines the significance of the recent demonstration of polar auxin transport (PAT) in the green macroalga Chara (Charophyceae: Charales) and, especially, options for explaining some features of PAT in the Charales. The occurrence of PAT in the Charales shows that PAT originated in the algal ancestors of the embryophytes (liverworts, mosses, hornworts, and vascular plants), although it is not yet known if PAT occurs elsewhere in the Charophyceae or in other algae. While in the embryophytes PAT occurs in parenchymatously constructed structures which commonly also have xylem and phloem (or their bryophyte analogues) as long-distance transport processes in parallel to PAT, in Chara corallina PAT shares the pathway for long-distance transport of nutrients though the parenchymatously constructed nodal complexes and the single giant cells of the internode. The speed of auxin movement of PAT is much more rapid than that attributable to diffusion and of the same order as the rate of cytoplasmic streaming in the giant internodal cells, yet complete inhibition of streaming by the inhibitor cytochalasin H does not slow down auxin transport. Explanations for this phenomenon are sought in the operation of other mechanochemical motors, dynein-tubulin and kinesin-tubulin, as alternatives to the myosin-actin system which powers cytoplasmic streaming. Experiments in which microtubules are disrupted, for example by colchicine, could show if one of the tubulin-based motors is involved. If these motors are involved, some mechanism is needed to amplify the speeds known for the motors to explain the order of magnitude higher speeds seen for auxin transport.
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Affiliation(s)
- John A Raven
- Division of Plant Sciences, University of Dundee at James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK.
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25
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Finet C, Jaillais Y. Auxology: when auxin meets plant evo-devo. Dev Biol 2012; 369:19-31. [PMID: 22687750 DOI: 10.1016/j.ydbio.2012.05.039] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Revised: 05/09/2012] [Accepted: 05/31/2012] [Indexed: 11/27/2022]
Abstract
Auxin is implicated throughout plant growth and development. Although the effects of this plant hormone have been recognized for more than a century, it is only in the past two decades that light has been shed on the molecular mechanisms that regulate auxin homeostasis, signaling, transport, crosstalk with other hormonal pathways as well as its roles in plant development. These discoveries established a molecular framework to study the role of auxin in land plant evolution. Here, we review recent advances in auxin biology and their implications in both micro- and macro-evolution of plant morphology. By analogy to the term 'hoxology', which refers to the critical role of HOX genes in metazoan evolution, we propose to introduce the term 'auxology' to take into account the crucial role of auxin in plant evo-devo.
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Affiliation(s)
- Cédric Finet
- Howard Hughes Medical Institute and Laboratory of Molecular Biology, University of Wisconsin, Madison, WI 53706, USA.
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26
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Xue XH, Guo CQ, Du F, Lu QL, Zhang CM, Ren HY. AtFH8 is involved in root development under effect of low-dose latrunculin B in dividing cells. MOLECULAR PLANT 2011; 4:264-78. [PMID: 21307369 DOI: 10.1093/mp/ssq085] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Formins have been paid much attention for their potent nucleating activity. However, the connection between the in vivo functions of AtFHs (Arabidopsis thaliana formin homologs) and their effects on actin organization is poorly understood. In this study, we characterized the bundling activity of AtFH8 in vitro and in vivo. Biochemical analysis showed that AtFH8(FH1FH2) could form dimers and bundle preformed actin filaments or induce stellar structures during actin polymerization. Expression of truncated forms of AtFH8 and immunolocalization analysis showed that AtFH8 localized primarily to nuclear envelope in interphase and to the new cell wall after cytokinesis, depending primarily on its N-terminal transmembrane domain. GUS histochemical staining showed AtFH8 was predominantly expressed in Arabidopsis root meristem, vasculature, and outgrowth points of lateral roots. The primary root growth and lateral root initiation of atfh8 could be decreased by latrunculin B (LatB). Analysis of the number of dividing cells in Arabidopsis root tips showed that much fewer dividing cells in Lat B-treated atfh8 plants than wild-type plants, which indicates that AtFH8 was involved in cell division. Actin cytoskeleton in root meristem of atfh8-1 was more sensitive to LatB treatment than that of wild-type. Altogether, our results indicate that AtFH8 is an actin filament nucleator and bundler that functions in cell division and root development.
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Affiliation(s)
- Xiu-Hua Xue
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education, College of Life Science, Beijing Normal University, Beijing 100875, China
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De Smet I, Beeckman T. Asymmetric cell division in land plants and algae: the driving force for differentiation. Nat Rev Mol Cell Biol 2011; 12:177-88. [PMID: 21346731 DOI: 10.1038/nrm3064] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Asymmetric cell division generates two cells with different fates and has an important role in plant development. It produces distinct cell types and new organs, and maintains stem cell niches. To handle the constraints of having immobile cells, plants possess numerous unique features to obtain asymmetry, such as specific regulators of intrinsic polarity. Although several components have not yet been identified, new findings, together with knowledge from different developmental systems, now allow us to take an important step towards a mechanistic overview of asymmetric cell division in plants and algae. Strikingly, several key regulators are used for different developmental processes, and common mechanisms can be recognized.
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Affiliation(s)
- Ive De Smet
- Plant and Crop Sciences Division, School of Biosciences, University of Nottingham, Loughborough LE12 5RD, UK.
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28
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Rasmussen CG, Humphries JA, Smith LG. Determination of symmetric and asymmetric division planes in plant cells. ANNUAL REVIEW OF PLANT BIOLOGY 2011; 62:387-409. [PMID: 21391814 DOI: 10.1146/annurev-arplant-042110-103802] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The cellular organization of plant tissues is determined by patterns of cell division and growth coupled with cellular differentiation. Cells proliferate mainly via symmetric division, whereas asymmetric divisions are associated with initiation of new developmental patterns and cell types. Division planes in both symmetrically and asymmetrically dividing cells are established through the action of a cortical preprophase band (PPB) of cytoskeletal filaments, which is disassembled upon transition to metaphase, leaving behind a cortical division site (CDS) to which the cytokinetic phragmoplast is later guided to position the cell plate. Recent progress has been made in understanding PPB formation and function as well as the nature and function of the CDS. In asymmetrically dividing cells, division plane establishment is governed by cell polarity. Recent work is beginning to shed light on polarization mechanisms in asymmetrically dividing cells, with receptor-like proteins and potential downstream effectors emerging as important players in this process.
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Affiliation(s)
- Carolyn G Rasmussen
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, California 92093, USA.
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29
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Le Bail A, Billoud B, Kowalczyk N, Kowalczyk M, Gicquel M, Le Panse S, Stewart S, Scornet D, Cock JM, Ljung K, Charrier B. Auxin metabolism and function in the multicellular brown alga Ectocarpus siliculosus. PLANT PHYSIOLOGY 2010; 153:128-44. [PMID: 20200071 PMCID: PMC2862433 DOI: 10.1104/pp.109.149708] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2009] [Accepted: 02/17/2010] [Indexed: 05/20/2023]
Abstract
Ectocarpus siliculosus is a small brown alga that has recently been developed as a genetic model. Its thallus is filamentous, initially organized as a main primary filament composed of elongated cells and round cells, from which branches differentiate. Modeling of its early development suggests the involvement of very local positional information mediated by cell-cell recognition. However, this model also indicates that an additional mechanism is required to ensure proper organization of the branching pattern. In this paper, we show that auxin indole-3-acetic acid (IAA) is detectable in mature E. siliculosus organisms and that it is present mainly at the apices of the filaments in the early stages of development. An in silico survey of auxin biosynthesis, conjugation, response, and transport genes showed that mainly IAA biosynthesis genes from land plants have homologs in the E. siliculosus genome. In addition, application of exogenous auxins and 2,3,5-triiodobenzoic acid had different effects depending on the developmental stage of the organism, and we propose a model in which auxin is involved in the negative control of progression in the developmental program. Furthermore, we identified an auxin-inducible gene called EsGRP1 from a small-scale microarray experiment and showed that its expression in a series of morphogenetic mutants was positively correlated with both their elongated-to-round cell ratio and their progression in the developmental program. Altogether, these data suggest that IAA is used by the brown alga Ectocarpus to relay cell-cell positional information and induces a signaling pathway different from that known in land plants.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | - Bénédicte Charrier
- CNRS-Université Pierre et Marie Curie, UMR 7139 Marine Plants and Biomolecules (A.L.B., B.B., N.K., M.G., S.S., D.S., J.M.C., B.C.), and Platform of Cytology, CNRS FR2424 (S.L.P.), Station Biologique de Roscoff, 29682 Roscoff cedex, France; Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University for Agricultural Sciences, S–901 83 Umea, Sweden (M.K., K.L.)
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30
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Nick P. Probing the actin-auxin oscillator. PLANT SIGNALING & BEHAVIOR 2010; 5:94-8. [PMID: 20023411 PMCID: PMC2884107 DOI: 10.4161/psb.5.2.10337] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Accepted: 10/15/2009] [Indexed: 05/20/2023]
Abstract
The directional transport of the plant hormone auxin depends on transcellular gradients of auxin-efflux carriers that continuously cycle between plasma membrane and intracellular compartments. This cycling has been proposed to depend on actin filaments. However, the role of actin for the polarity of auxin transport has been disputed. To get insight into this question, actin bundling was induced by overexpression of the actin-binding domain of talin in tobacco BY-2 cells and in rice plants. This bundling can be reverted by addition of auxins, which allows to address the role of actin organization on the flux of auxin. In both systems, the reversion of a normal actin configuration can be restored by addition of exogenous auxins and this fully restores the respective auxin-dependent functions. These findings lead to a model of a self-referring regulatory circuit between polar auxin transport and actin organization. To further dissect the actin-auxin oscillator, we used photoactivated release of caged auxin in tobacco cells to demonstrate that auxin gradients can be manipulated at a subcellular level.
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Affiliation(s)
- Peter Nick
- Molecular Cell Biology, Botanical Institute, Karlsruhe Institute of Technology, Karlsruhe, Germany.
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31
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Nick P, Han MJ, An G. Auxin stimulates its own transport by shaping actin filaments. PLANT PHYSIOLOGY 2009; 151:155-67. [PMID: 19633235 PMCID: PMC2736007 DOI: 10.1104/pp.109.140111] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2009] [Accepted: 07/17/2009] [Indexed: 05/18/2023]
Abstract
The directional transport of the plant hormone auxin has been identified as central element of axis formation and patterning in plants. This directionality of transport depends on gradients, across the cell, of auxin-efflux carriers that continuously cycle between plasma membrane and intracellular compartments. This cycling has been proposed to depend on actin filaments. However, the role of actin for the polarity of auxin transport has been disputed. The organization of actin, in turn, has been shown to be under control of auxin. By overexpression of the actin-binding protein talin, we have generated transgenic rice (Oryza sativa) lines, where actin filaments are bundled to variable extent and, in consequence, display a reduced dynamics. We show that this bundling of actin filaments correlates with impaired gravitropism and reduced longitudinal transport of auxin. We can restore a normal actin configuration by addition of exogenous auxins and restore gravitropism as well as polar auxin transport. This rescue is mediated by indole-3-acetic acid and 1-naphthyl acetic acid but not by 2,4-dichlorophenoxyacetic acid. We interpret these findings in the context of a self-referring regulatory circuit between polar auxin transport and actin organization. This circuit might contribute to the self-amplification of auxin transport that is a central element in current models of auxin-dependent patterning.
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Affiliation(s)
- Peter Nick
- Institute of Botany 1, University of Karlsruhe, D-76128 Karlsruhe, Germany.
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32
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Lau S, Shao N, Bock R, Jürgens G, De Smet I. Auxin signaling in algal lineages: fact or myth? TRENDS IN PLANT SCIENCE 2009; 14:182-8. [PMID: 19285905 DOI: 10.1016/j.tplants.2009.01.004] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2008] [Revised: 01/08/2009] [Accepted: 01/12/2009] [Indexed: 05/05/2023]
Abstract
Auxin is of major importance throughout the life cycle of a plant, affecting several physiological and developmental processes, such as cell expansion and division. However, the evolutionary time point at which auxin became involved in such diverse processes is currently unclear. Despite some controversy, numerous reports demonstrate the presence of auxin in algal lineages and its effects on algal development, suggesting an early evolutionary origin of auxin-dependent mechanisms. Here, we review these reports and discuss in silico analyses of auxin signaling components. It seems that, at least in microalgae, the assumed major components of auxin signaling in land plants are absent. However, these microalgae might have alternative auxin signaling pathways that could account for their responses to auxin.
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Affiliation(s)
- Steffen Lau
- Center for Plant Molecular Biology (ZMBP), Developmental Genetics, Tübingen University, Auf der Morgenstelle 3, D-72076 Tübingen, Germany
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33
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Le Bail A, Billoud B, Maisonneuve C, Peters AF, Mark Cock J, Charrier B. EARLY DEVELOPMENT PATTERN OF THE BROWN ALGA ECTOCARPUS SILICULOSUS (ECTOCARPALES, PHAEOPHYCEAE) SPOROPHYTE(1). JOURNAL OF PHYCOLOGY 2008; 44:1269-81. [PMID: 27041723 DOI: 10.1111/j.1529-8817.2008.00582.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The distant phylogenetic position of brown macroalgae from the other multicellular phyla offers the opportunity to study novel and alternative developmental processes involved in the establishment of multicellularity. At present, however, very little information is available about developmental patterning in this group. Ectocarpus siliculosus (Dillwyn) Lyngb. has uniseriate filaments and displays one of the simplest architectures in the Phaeophyceae. The aim of this study was to decipher the morphogenetic steps that lead to the development of the Ectocarpus sporophyte. We carried out a detailed morphometric study of the events that occurred between gamete germination and the 100-cell stage. This analysis was performed on two ecologically distant isolates to assess plasticity in developmental patterning within this species. Cell sizes were measured in both isolates, allowing the definition of two main cell types based on their shape (round and elongated). On average, the filament is composed of about 40% round cells, which are present in the central region of the filament, but different combinations of the two cell types within filaments were observed and quantified. Young sporophytes grew apically, with elongated cells progressively differentiating into round cells. Secondary filaments emerged preferentially on round cells, primarily from the older central cells. Statistical analyses showed that the pattern of branching was regulated to ensure a stereotyped architecture. This description of the developmental patterning during the growth of the E. siliculosus sporophyte will serve as a base for more detailed studies of development, in this species and in brown algae in general.
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Affiliation(s)
- Aude Le Bail
- UPMC Univ Paris 6, UMR 7139 Végétaux marins et Biomolécules, Station Biologique, F 29682, Roscoff, France CNRS, UMR 7139 Végétaux marins et Biomolécules, Station Biologique, F 29682, Roscoff, FranceUPMC Univ Paris 06, Atelier de BioInformatique, MB1202, 75005 Paris, France UPMC Univ Paris 6, UMR 7139 Végétaux marins et Biomolécules, Station Biologique, F 29682, Roscoff, France CNRS, UMR 7139 Végétaux marins et Biomolécules, Station Biologique, F 29682, Roscoff, France
| | - Bernard Billoud
- UPMC Univ Paris 6, UMR 7139 Végétaux marins et Biomolécules, Station Biologique, F 29682, Roscoff, France CNRS, UMR 7139 Végétaux marins et Biomolécules, Station Biologique, F 29682, Roscoff, FranceUPMC Univ Paris 06, Atelier de BioInformatique, MB1202, 75005 Paris, France UPMC Univ Paris 6, UMR 7139 Végétaux marins et Biomolécules, Station Biologique, F 29682, Roscoff, France CNRS, UMR 7139 Végétaux marins et Biomolécules, Station Biologique, F 29682, Roscoff, France
| | - Carole Maisonneuve
- UPMC Univ Paris 6, UMR 7139 Végétaux marins et Biomolécules, Station Biologique, F 29682, Roscoff, France CNRS, UMR 7139 Végétaux marins et Biomolécules, Station Biologique, F 29682, Roscoff, FranceUPMC Univ Paris 06, Atelier de BioInformatique, MB1202, 75005 Paris, France UPMC Univ Paris 6, UMR 7139 Végétaux marins et Biomolécules, Station Biologique, F 29682, Roscoff, France CNRS, UMR 7139 Végétaux marins et Biomolécules, Station Biologique, F 29682, Roscoff, France
| | - Akira F Peters
- UPMC Univ Paris 6, UMR 7139 Végétaux marins et Biomolécules, Station Biologique, F 29682, Roscoff, France CNRS, UMR 7139 Végétaux marins et Biomolécules, Station Biologique, F 29682, Roscoff, FranceUPMC Univ Paris 06, Atelier de BioInformatique, MB1202, 75005 Paris, France UPMC Univ Paris 6, UMR 7139 Végétaux marins et Biomolécules, Station Biologique, F 29682, Roscoff, France CNRS, UMR 7139 Végétaux marins et Biomolécules, Station Biologique, F 29682, Roscoff, France
| | - J Mark Cock
- UPMC Univ Paris 6, UMR 7139 Végétaux marins et Biomolécules, Station Biologique, F 29682, Roscoff, France CNRS, UMR 7139 Végétaux marins et Biomolécules, Station Biologique, F 29682, Roscoff, FranceUPMC Univ Paris 06, Atelier de BioInformatique, MB1202, 75005 Paris, France UPMC Univ Paris 6, UMR 7139 Végétaux marins et Biomolécules, Station Biologique, F 29682, Roscoff, France CNRS, UMR 7139 Végétaux marins et Biomolécules, Station Biologique, F 29682, Roscoff, France
| | - Bénédicte Charrier
- UPMC Univ Paris 6, UMR 7139 Végétaux marins et Biomolécules, Station Biologique, F 29682, Roscoff, France CNRS, UMR 7139 Végétaux marins et Biomolécules, Station Biologique, F 29682, Roscoff, FranceUPMC Univ Paris 06, Atelier de BioInformatique, MB1202, 75005 Paris, France UPMC Univ Paris 6, UMR 7139 Végétaux marins et Biomolécules, Station Biologique, F 29682, Roscoff, France CNRS, UMR 7139 Végétaux marins et Biomolécules, Station Biologique, F 29682, Roscoff, France
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Lau S, Jürgens G, De Smet I. The evolving complexity of the auxin pathway. THE PLANT CELL 2008; 20:1738-46. [PMID: 18647826 PMCID: PMC2518236 DOI: 10.1105/tpc.108.060418] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Affiliation(s)
- Steffen Lau
- Center for Plant Molecular Biology, Developmental Genetics, Tübingen University, D-72076 Tübingen, Germany
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Robert C, Noriega A, Tocino A, Cervantes E. Morphological analysis of seed shape in Arabidopsis thaliana reveals altered polarity in mutants of the ethylene signaling pathway. JOURNAL OF PLANT PHYSIOLOGY 2008; 165:911-919. [PMID: 18155318 DOI: 10.1016/j.jplph.2007.10.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2007] [Revised: 07/03/2007] [Accepted: 10/01/2007] [Indexed: 05/25/2023]
Abstract
The shape of Arabidopsis thaliana dry seed is described here as a prolate spheroid. The accuracy of this approximation is discussed. Considering its limitations, it allows a geometric approximation to the analysis of changes occurring in seed shape during imbibition prior to seed germination as well as the differences in shape between genotypes and their changes during imbibition. The triple mutant ein2-1, ers1-2, etr1-7 presents notable alterations in seed shape. In addition, seeds of this and other mutants in the ethylene signaling pathway (ctr1-1, eto1-1, etr1-1, ein2-1) show different response to imbibition than the wild type. Imbibed seeds of the wild type increase their asymmetry compared with the dry seeds. This is detected by the relative changes in the curvature values in both poles. Thus, during imbibition of the wild-type seeds, the reduction in curvature values observed in the basal pole gives them an ovoid shape. In contrast, in the seeds of the ethylene mutants, reduction in curvature values occurs in both basal and apical poles, and its shape remains as a prolate spheroid. Our data indicate that the ethylene signaling pathway is involved, in general, in the complex regulation of seed shape and, in particular, in the establishment of polarity in seeds, controlling curvature values in the seed poles.
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Affiliation(s)
- Céline Robert
- Departamento de Producción Vegetal, IRNASA-CSIC, Salamanca, Apartado 257, Salamanca, Spain
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36
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Holweg CL. Acto-Myosin motorises the flow of auxin. PLANT SIGNALING & BEHAVIOR 2007; 2:247-248. [PMID: 19704667 PMCID: PMC2634136 DOI: 10.4161/psb.2.4.3864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2007] [Accepted: 01/16/2007] [Indexed: 05/28/2023]
Abstract
Auxin has always been a hormone of intensive investigation because of its crucial roles in plant growth. With the recent confirmation of PIN1 and AUX1 as proteins specifically controlling auxin distribution, the ongoing debate about possible mechanisms in polar auxin transport (PAT) made further progress. Another new set of data suggested vesicle-based processes to have meaningful roles in auxin pathways. This view got additional support by the finding that cytoplasmic streaming as well as PAT decreased under inhibition of actin or myosin. Inhibitory effects on both events were also observed when actin-binding proteins (ABPs) were overexpressed for fluorescent actin-labelling. Here, the block of motility was reasoned by myosins and ABPs competing for F-actin binding. In summary, the observations constantly show that acto-myosin controls the motility of vesicles and in parallel, is essential for directional auxin flow. A direct functional link between PAT and vesicles can not be concluded from these experiments, but might be either understood as the shuttling of components of the auxin-efflux machinery by myosin-guided vesicles, or, in the more unusual meaning of PAT by secretion, as the delivery of auxin in membraneous compartments moved by myosin.
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Iwano M, Shiba H, Matoba K, Miwa T, Funato M, Entani T, Nakayama P, Shimosato H, Takaoka A, Isogai A, Takayama S. Actin dynamics in papilla cells of Brassica rapa during self- and cross-pollination. PLANT PHYSIOLOGY 2007; 144:72-81. [PMID: 17337527 PMCID: PMC1913780 DOI: 10.1104/pp.106.095273] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2006] [Accepted: 02/17/2007] [Indexed: 05/14/2023]
Abstract
The self-incompatibility system of the plant species Brassica is controlled by the S-locus, which contains S-RECEPTOR KINASE (SRK) and S-LOCUS PROTEIN11 (SP11). SP11 binding to SRK induces SRK autophosphorylation and initiates a signaling cascade leading to the rejection of self pollen. However, the mechanism controlling hydration and germination arrest during self-pollination is unclear. In this study, we examined the role of actin, a key cytoskeletal component regulating the transport system for hydration and germination in the papilla cell during pollination. Using rhodamine-phalloidin staining, we showed that cross-pollination induced actin polymerization, whereas self-pollination induced actin reorganization and likely depolymerization. By monitoring transiently expressed green fluorescent protein fused to the actin-binding domain of mouse talin, we observed the concentration of actin bundles at the cross-pollen attachment site and actin reorganization and likely depolymerization at the self-pollen attachment site; the results correspond to those obtained by rhodamine-phalloidin staining. We further showed that the coat of self pollen is sufficient to mediate this response. The actin-depolymerizing drug cytochalasin D significantly inhibited pollen hydration and germination during cross-pollination, further emphasizing a role for actin in these processes. Additionally, three-dimensional electron microscopic tomography revealed the close association of the actin cytoskeleton with an apical vacuole network. Self-pollination disrupted the vacuole network, whereas cross-pollination led to vacuolar rearrangements toward the site of pollen attachment. Taken together, our data suggest that self- and cross-pollination differentially affect the dynamics of the actin cytoskeleton, leading to changes in vacuolar structure associated with hydration and germination.
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Affiliation(s)
- Megumi Iwano
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara 630-0101, Japan.
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Schlicht M, Strnad M, Scanlon MJ, Mancuso S, Hochholdinger F, Palme K, Volkmann D, Menzel D, Baluska F. Auxin immunolocalization implicates vesicular neurotransmitter-like mode of polar auxin transport in root apices. PLANT SIGNALING & BEHAVIOR 2006; 1:122-33. [PMID: 19521492 PMCID: PMC2635008 DOI: 10.4161/psb.1.3.2759] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2006] [Accepted: 04/03/2006] [Indexed: 05/18/2023]
Abstract
Immunolocalization of auxin using a new specific antibody revealed, besides the expected diffuse cytoplasmic signal, enrichments of auxin at end-poles (cross-walls), within endosomes and within nuclei of those root apex cells which accumulate abundant F-actin at their end-poles. In Brefeldin A (BFA) treated roots, a strong auxin signal was scored within BFA-induced compartments of cells having abundant actin and auxin at their end-poles, as well as within adjacent endosomes, but not in other root cells. Importantly, several types of polar auxin transport (PAT) inhibitors exert similar inhibitory effects on endocytosis, vesicle recycling, and on the enrichments of F-actin at the end-poles. These findings indicate that auxin is transported across F-actin-enriched end-poles (synapses) via neurotransmitter-like secretion. This new concept finds genetic support from the semaphore1, rum1 and rum1/lrt1 mutants of maize which are impaired in PAT, endocytosis and vesicle recycling, as well as in recruitment of F-actin and auxin to the auxin transporting end-poles. Although PIN1 localizes abundantly to the end-poles, and they also fail to support the formation of in these mutants affected in PAT, auxin and F-actin are depleted from their end-poles which also fail to support formation of the large BFA-induced compartments.
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Affiliation(s)
- Markus Schlicht
- IZMB; Rheinische Friedrich-Wilhelms-Universität; Bonn, Germany
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Mancuso S, Barlow PW, Volkmann D, Baluska F. Actin turnover-mediated gravity response in maize root apices: gravitropism of decapped roots implicates gravisensing outside of the root cap. PLANT SIGNALING & BEHAVIOR 2006; 1:52-8. [PMID: 19521476 PMCID: PMC2633879 DOI: 10.4161/psb.1.2.2432] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2005] [Accepted: 10/31/2005] [Indexed: 05/08/2023]
Abstract
The dynamic actin cytoskeleton has been proposed to be linked to gravity sensing in plants but the mechanistic understanding of these processes remains unknown. We have performed detailed pharmacological analyses of the role of the dynamic actin cytoskeleton in gravibending of maize (Zea mays) root apices. Depolymerization of actin filaments with two drugs having different mode of their actions, cytochalasin D and latrunculin B, stimulated root gravibending. By contrast, drug-induced stimulation of actin polymerization and inhibition of actin turnover, using two different agents phalloidin and jasplakinolide, compromised the root gravibending. Importantly, all these actin drugs inhibited root growth to similar extents suggesting that high actin turnover is essential for the gravity-related growth responses rather than for the general growth process. Both latrunculin B and cytochalasin D treatments inhibited root growth but restored gravibending of the decapped root apices, indicating that there is a strong potential for effective actin-mediated gravity sensing outside the cap. This elusive gravity sensing outside the root cap is dependent not only on the high rate of actin turnover but also on weakening of myosin activities, as general inhibition of myosin ATPases induced stimulation of gravibending of the decapped root apices. Collectively, these data provide evidence for the actin turnover-mediated gravity sensing outside the root cap.
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Affiliation(s)
- Stefano Mancuso
- Electrophysiology Laboratory; Department of Horticulture; University of Florence; Sesto Fiorentino, Italy
| | - Peter W Barlow
- School of Biological Sciences; University of Bristol; Woodland Road; Bristol, UK
| | - Dieter Volkmann
- Rheinische Friedrich-Wilhelms-University of Bonn; Institute of Cellular and Molecular Botany; Bonn, Germany
| | - Frantisek Baluska
- Rheinische Friedrich-Wilhelms-University of Bonn; Institute of Cellular and Molecular Botany; Bonn, Germany
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40
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Blancaflor EB, Wang YS, Motes CM. Organization and function of the actin cytoskeleton in developing root cells. INTERNATIONAL REVIEW OF CYTOLOGY 2006; 252:219-64. [PMID: 16984819 DOI: 10.1016/s0074-7696(06)52004-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The actin cytoskeleton is a highly dynamic structure, which mediates various cellular functions in large part through accessory proteins that tilt the balance between monomeric G-actin and filamentous actin (F-actin) or by facilitating interactions between actin and the plasma membrane, microtubules, and other organelles. Roots have become an attractive model to study actin in plant development because of their simple anatomy and accessibility of some root cell types such as root hairs for microscopic analyses. Roots also exhibit a remarkable developmental plasticity and possess a delicate sensory system that is easily manipulated, so that one can design experiments addressing a range of important biological questions. Many facets of root development can be regulated by the diverse actin network found in the various root developmental regions. Various molecules impinge on this actin scaffold to define how a particular root cell type grows or responds to a specific environmental signal. Although advances in genomics are leading the way toward elucidating actin function in roots, more significant strides will be realized when such tools are combined with improved methodologies for accurately depicting how actin is organized in plant cells.
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Affiliation(s)
- Elison B Blancaflor
- Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401, USA
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Baluska F, Hlavacka A. Plant formins come of age: something special about cross-walls. THE NEW PHYTOLOGIST 2005; 168:499-503. [PMID: 16313632 DOI: 10.1111/j.1469-8137.2005.01595.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Affiliation(s)
- Frantisek Baluska
- Institute of Cellular and Molecular Botany, University of Bonn, Bonn, Germany.
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42
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Dhonukshe P, Kleine-Vehn J, Friml J. Cell polarity, auxin transport, and cytoskeleton-mediated division planes: who comes first? PROTOPLASMA 2005; 226:67-73. [PMID: 16231102 DOI: 10.1007/s00709-005-0104-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2005] [Accepted: 03/30/2005] [Indexed: 05/04/2023]
Abstract
In plants, cell polarity is an issue more recurring than in other systems, because plants, due to their adaptive and flexible development, often change cell polarity postembryonically according to intrinsic cues and demands of the environment. Recent findings on the directional movement of the plant signalling molecule auxin provide a unique connection between individual cell polarity and the establishment of polarity at the tissue, organ, and whole-plant levels. Decisions about the subcellular polar targeting of PIN auxin transport components determine the direction of auxin flow between cells and consequently mediate multiple developmental events. In addition, mutations or chemical interference with PIN-based auxin transport result in abnormal cell divisions. Thus, the complicated links between cell polarity establishment, auxin transport, cytoskeleton, and oriented cell divisions now begin to emerge. Here we review the available literature on the issues of cell polarity in both plants and animals to extend our understanding on the generation, maintenance, and transmission of cell polarity in plants.
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Affiliation(s)
- Pankaj Dhonukshe
- Zentrum für Molekularbiologie der Pflanzen, Universität Tübingen, Tübingen, Federal Republic of Germany.
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Li L, Xu J, Xu ZH, Xue HW. Brassinosteroids stimulate plant tropisms through modulation of polar auxin transport in Brassica and Arabidopsis. THE PLANT CELL 2005; 17:2738-53. [PMID: 16141452 PMCID: PMC1242269 DOI: 10.1105/tpc.105.034397] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Brassinosteroids (BRs) are important plant growth regulators in multiple developmental processes. Previous studies have indicated that BR treatment enhanced auxin-related responses, but the underlying mechanisms remain unknown. Using (14)C-labeled indole-3-acetic acid and Arabidopsis thaliana plants harboring an auxin-responsive reporter construct, we show that the BR brassinolide (BL) stimulates polar auxin transport capacities and modifies the distribution of endogenous auxin. In plants treated with BL or defective in BR biosynthesis or signaling, the transcription of PIN genes, which facilitate functional auxin transport in plants, was differentially regulated. In addition, BL enhanced plant tropistic responses by promoting the accumulation of the PIN2 protein from the root tip to the elongation zone and stimulating the expression and dispersed localization of ROP2 during tropistic responses. Constitutive overexpression of ROP2 results in enhanced polar accumulation of PIN2 protein in the root elongation region and increased gravitropism, which is significantly affected by latrunculin B, an inhibitor of F-actin assembly. The ROP2 dominant negative mutants (35S-ROP2-DA/DN) show delayed tropistic responses, and this delay cannot be reversed by BL addition, strongly supporting the idea that ROP2 modulates the functional localization of PIN2 through regulation of the assembly/reassembly of F-actins, thereby mediating the BR effects on polar auxin transport and tropistic responses.
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Affiliation(s)
- Li Li
- National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 200032 Shanghai, China
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Voigt B, Timmers ACJ, Samaj J, Müller J, Baluska F, Menzel D. GFP-FABD2 fusion construct allows in vivo visualization of the dynamic actin cytoskeleton in all cells of Arabidopsis seedlings. Eur J Cell Biol 2005; 84:595-608. [PMID: 16032928 DOI: 10.1016/j.ejcb.2004.11.011] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
In vivo visualization of filamentous actin in all cells of Arabidopsis thaliana seedlings is essential for understanding the numerous roles of the actin cytoskeleton in diverse processes of cell differentiation. A previously introduced reporter construct based on the actin-binding domain of mouse talin proved to be useful for unravelling some of these aspects in cell layers close to the organ surface. However, cells more deeply embedded, especially stelar cells active in polar transport of auxin, show either diffuse or no fluorescence at all due to the lack of expression of the fusion protein. The same problem is encountered in the root meristem. Recently introduced actin reporters based on fusions between A. thaliana fimbrin 1 and GFP gave brilliant results in organs from the root differentiation zone upwards to the leaves, however failed to depict the filamentous actin cytoskeleton in the transition zone of the root, in the apical meristem and the root cap. To overcome these problems, we have prepared new transgenic lines for the visualization of F-actin in vivo. We report here that a construct consisting of GFP fused to the C-terminal half of A. thaliana fimbrin 1 reveals dynamic arrays of F-actin in all cells of stably transformed A. thaliana seedlings.
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Affiliation(s)
- Boris Voigt
- Department of Plant Cell Biology, Institute of Cellular and Molecular Botany, Rheinische Friedrich-Wilhelms-University of Bonn, Kirschallee 1, D-53115 Bonn, Germany
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Abstract
BACKGROUND The phytohormone auxin is critical for plant growth and orchestrates many developmental processes. SCOPE This review considers the complex array of mechanisms plants use to control auxin levels, the movement of auxin through the plant, the emerging view of auxin-signalling mechanisms, and several interactions between auxin and other phytohormones. Though many natural and synthetic compounds exhibit auxin-like activity in bioassays, indole-3-acetic acid (IAA) is recognized as the key auxin in most plants. IAA is synthesized both from tryptophan (Trp) using Trp-dependent pathways and from an indolic Trp precursor via Trp-independent pathways; none of these pathways is fully elucidated. Plants can also obtain IAA by beta-oxidation of indole-3-butyric acid (IBA), a second endogenous auxin, or by hydrolysing IAA conjugates, in which IAA is linked to amino acids, sugars or peptides. To permanently inactivate IAA, plants can employ conjugation and direct oxidation. Consistent with its definition as a hormone, IAA can be transported the length of the plant from the shoot to the root; this transport is necessary for normal development, and more localized transport is needed for tropic responses. Auxin signalling is mediated, at least in large part, by an SCFTIR1 E3 ubiquitin ligase complex that accelerates Aux/IAA repressor degradation in response to IAA, thereby altering gene expression. Two classes of auxin-induced genes encode negatively acting products (the Aux/IAA transcriptional repressors and GH3 family of IAA conjugating enzymes), suggesting that timely termination of the auxin signal is crucial. Auxin interaction with other hormone signals adds further challenges to understanding auxin response. CONCLUSIONS Nearly six decades after the structural elucidation of IAA, many aspects of auxin metabolism, transport and signalling are well established; however, more than a few fundamental questions and innumerable details remain unresolved.
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