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Liu L, Wang Y, Cao W, Yang L, Zhang C, Yuan L, Wang D, Wang W, Zhang H, Schiefelbein J, Yu F, An L. TRANSPARENT TESTA GLABRA2 defines trichome cell shape by modulating actin cytoskeleton in Arabidopsis thaliana. PLANT PHYSIOLOGY 2024; 195:1256-1276. [PMID: 38391271 DOI: 10.1093/plphys/kiae091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 01/11/2024] [Accepted: 01/17/2024] [Indexed: 02/24/2024]
Abstract
The Arabidopsis (Arabidopsis thaliana) TRANSPARENT TESTA GLABRA2 (TTG2) gene encodes a WRKY transcription factor that regulates a range of development events like trichome, seed coat, and atrichoblast formation. Loss-of-function of TTG2 was previously shown to reduce or eliminate trichome specification and branching. Here, we report the identification of an allele of TTG2, ttg2-6. In contrast to the ttg2 mutants described before, ttg2-6 displayed unique trichome phenotypes. Some ttg2-6 mutant trichomes were hyper-branched, whereas others were hypo-branched, distorted, or clustered. Further, we found that in addition to specifically activating R3 MYB transcription factor TRIPTYCHON (TRY) to modulate trichome specification, TTG2 also integrated cytoskeletal signaling to regulate trichome morphogenesis. The ttg2-6 trichomes displayed aberrant cortical microtubules (cMTs) and actin filaments (F-actin) configurations. Moreover, genetic and biochemical analyses showed that TTG2 could directly bind to the promoter and regulate the expression of BRICK1 (BRK1), which encodes a subunit of the actin nucleation promoting complex suppressor of cyclic AMP repressor (SCAR)/Wiskott-Aldrich syndrome protein family verprolin homologous protein (WAVE). Collectively, taking advantage of ttg2-6, we uncovered a function for TTG2 in facilitating cMTs and F-actin cytoskeleton-dependent trichome development, providing insight into cellular signaling events downstream of the core transcriptional regulation during trichome development in Arabidopsis.
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Affiliation(s)
- Lu Liu
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Yali Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Weihua Cao
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Lan Yang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Chi Zhang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Lanxin Yuan
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Dan Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Wenjia Wang
- CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Hongchang Zhang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - John Schiefelbein
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Fei Yu
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Lijun An
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
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2
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Martinek J, Cifrová P, Vosolsobě S, García-González J, Malínská K, Mauerová Z, Jelínková B, Krtková J, Sikorová L, Leaves I, Sparkes I, Schwarzerová K. ARP2/3 complex associates with peroxisomes to participate in pexophagy in plants. NATURE PLANTS 2023; 9:1874-1889. [PMID: 37845336 DOI: 10.1038/s41477-023-01542-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 09/11/2023] [Indexed: 10/18/2023]
Abstract
Actin-related protein (ARP2/3) complex is a heteroheptameric protein complex, evolutionary conserved in all eukaryotic organisms. Its conserved role is based on the induction of actin polymerization at the interface between membranes and the cytoplasm. Plant ARP2/3 has been reported to participate in actin reorganization at the plasma membrane during polarized growth of trichomes and at the plasma membrane-endoplasmic reticulum contact sites. Here we demonstrate that individual plant subunits of ARP2/3 fused to fluorescent proteins form motile spot-like structures in the cytoplasm that are associated with peroxisomes in Arabidopsis and tobacco. ARP2/3 is found at the peroxisome periphery and contains the assembled ARP2/3 complex and the WAVE/SCAR complex subunit NAP1. This ARP2/3-positive peroxisomal domain colocalizes with the autophagosome and, under conditions that affect the autophagy, colocalization between ARP2/3 and the autophagosome increases. ARP2/3 subunits co-immunoprecipitate with ATG8f and peroxisome-associated ARP2/3 interact in vivo with the ATG8f marker. Since mutants lacking functional ARP2/3 complex have more peroxisomes than wild type, we suggest that ARP2/3 has a novel role in the process of peroxisome degradation by autophagy, called pexophagy.
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Affiliation(s)
- Jan Martinek
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Petra Cifrová
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Stanislav Vosolsobě
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Judith García-González
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Kateřina Malínská
- Imaging Facility of Institute of Experimental Botany AS CR, Prague, Czech Republic
| | - Zdeňka Mauerová
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Barbora Jelínková
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Jana Krtková
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Lenka Sikorová
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Ian Leaves
- Biosciences, CLES, Exeter University, Exeter, UK
| | - Imogen Sparkes
- School of Biological Sciences, University of Bristol, Bristol, UK
| | - Kateřina Schwarzerová
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czech Republic.
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Yoshida MW, Kozgunova E. Microfluidic Device for High-Resolution Cytoskeleton Imaging and Washout Assays in Physcomitrium (Physcomitrella) patens. Methods Mol Biol 2023; 2604:143-158. [PMID: 36773231 DOI: 10.1007/978-1-0716-2867-6_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
Visualizing cytoskeleton dynamics at high spatiotemporal resolution provides valuable insights into the way the dynamics change as well as its interactions with multiple proteins in order to maintain cellular function. Oblique illumination fluorescent microscopy is a popular technique to image cellular events localized near the plasma membrane. In this chapter, we provide detailed protocols for high-resolution cytoskeleton imaging using protonema and gametophore cells of the moss Physcomitrella (Physcomitrium patens) in the microfluidic device. These include preparation of the polydimethylsiloxane (PDMS) device, culture of moss cells, and both short- and long-term oblique illumination fluorescent microscopy. We also describe how to introduce to, and wash out from, the device chemical compounds, such as microtubule-disrupting drugs, during live-cell imaging.
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Affiliation(s)
- Mari W Yoshida
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi, Japan
| | - Elena Kozgunova
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi, Japan. .,Institute for Advanced Research, Nagoya University, Nagoya, Japan.
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4
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Bellinvia E, García-González J, Cifrová P, Martinek J, Sikorová L, Havelková L, Schwarzerová K. CRISPR-Cas9 Arabidopsis mutants of genes for ARPC1 and ARPC3 subunits of ARP2/3 complex reveal differential roles of complex subunits. Sci Rep 2022; 12:18205. [PMID: 36307477 PMCID: PMC9616901 DOI: 10.1038/s41598-022-22982-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2022] [Accepted: 10/21/2022] [Indexed: 12/31/2022] Open
Abstract
Protein complex Arp2/3 has a conserved role in the nucleation of branched actin filaments. It is constituted of seven subunits, including actin-like subunits ARP2 and ARP3 plus five other subunits called Arp2/3 Complex Component 1 to 5, which are not related to actin. Knock-out plant mutants lacking individual plant ARP2/3 subunits have a typical phenotype of distorted trichomes, altered pavement cells shape and defects in cell adhesion. While knock-out mutant Arabidopsis plants for most ARP2/3 subunits have been characterized before, Arabidopsis plant mutants missing ARPC1 and ARPC3 subunits have not yet been described. Using CRISPR/Cas9, we generated knock-out mutants lacking ARPC1 and ARPC3 subunits. We confirmed that the loss of ARPC1 subunits results in the typical ARP2/3 mutant phenotype. However, the mutants lacking ARPC3 subunits resulted in plants with surprisingly different phenotypes. Our results suggest that plant ARP2/3 complex function in trichome shaping does not require ARPC3 subunit, while the fully assembled complex is necessary for the establishment of correct cell adhesion in the epidermis.
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Affiliation(s)
- Erica Bellinvia
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Judith García-González
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Petra Cifrová
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Jan Martinek
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Lenka Sikorová
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Lenka Havelková
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Kateřina Schwarzerová
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czech Republic.
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Bao L, Ren J, Nguyen M, Slusarczyk AS, Thole JM, Martinez SP, Huang J, Fujita T, Running MP. The cellular function of ROP GTPase prenylation is important for multicellularity in the moss Physcomitrium patens. Development 2022; 149:275605. [DOI: 10.1242/dev.200279] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 05/24/2022] [Indexed: 01/27/2023]
Abstract
ABSTRACT
A complete picture of how signaling pathways lead to multicellularity is largely unknown. Previously, we generated mutations in a protein prenylation enzyme, GGB, and showed that it is essential for maintaining multicellularity in the moss Physcomitrium patens. Here, we show that ROP GTPases act as downstream factors that are prenylated by GGB and themselves play an important role in the multicellularity of P. patens. We also show that the loss of multicellularity caused by the suppression of GGB or ROP GTPases is due to uncoordinated cell expansion, defects in cell wall integrity and the disturbance of the directional control of cell plate orientation. Expressing prenylatable ROP in the ggb mutant not only rescues multicellularity in protonemata but also results in development of gametophores. Although the prenylation of ROP is important for multicellularity, a higher threshold of active ROP is required for gametophore development. Thus, our results suggest that ROP activation via prenylation by GGB is a key process at both cell and tissue levels, facilitating the developmental transition from one dimension to two dimensions and to three dimensions in P. patens.
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Affiliation(s)
- Liang Bao
- University of Louisville 1 Department of Biology , , Louisville, KY 40208 , USA
| | - Junling Ren
- University of Louisville 1 Department of Biology , , Louisville, KY 40208 , USA
| | - Mary Nguyen
- University of Louisville 1 Department of Biology , , Louisville, KY 40208 , USA
| | | | - Julie M. Thole
- Saint Louis University 3 Department of Biology , , St Louis, MO 63103 , USA
| | | | - Jinling Huang
- East Carolina University 4 Department of Biology , , Greenville, NC 27858
| | - Tomomichi Fujita
- Hokkaido University 5 Faculty of Science , , Sapporo 060-0810 , Japan
| | - Mark P. Running
- University of Louisville 1 Department of Biology , , Louisville, KY 40208 , USA
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Chin S, Kwon T, Khan BR, Sparks JA, Mallery EL, Szymanski DB, Blancaflor EB. Spatial and temporal localization of SPIRRIG and WAVE/SCAR reveal roles for these proteins in actin-mediated root hair development. THE PLANT CELL 2021; 33:2131-2148. [PMID: 33881536 PMCID: PMC8364238 DOI: 10.1093/plcell/koab115] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 04/15/2021] [Indexed: 05/31/2023]
Abstract
Root hairs are single-cell protrusions that enable roots to optimize nutrient and water acquisition. These structures attain their tubular shapes by confining growth to the cell apex, a process called tip growth. The actin cytoskeleton and endomembrane systems are essential for tip growth; however, little is known about how these cellular components coordinate their activities during this process. Here, we show that SPIRRIG (SPI), a beige and Chediak Higashi domain-containing protein involved in membrane trafficking, and BRK1 and SCAR2, subunits of the WAVE/SCAR (W/SC) actin nucleating promoting complex, display polarized localizations in Arabidopsis thaliana root hairs during distinct developmental stages. SPI accumulates at the root hair apex via post-Golgi compartments and positively regulates tip growth by maintaining tip-focused vesicle secretion and filamentous-actin integrity. BRK1 and SCAR2 on the other hand, mark the root hair initiation domain to specify the position of root hair emergence. Consistent with the localization data, tip growth was reduced in spi and the position of root hair emergence was disrupted in brk1 and scar1234. BRK1 depletion coincided with SPI accumulation as root hairs transitioned from initiation to tip growth. Taken together, our work uncovers a role for SPI in facilitating actin-dependent root hair development in Arabidopsis through pathways that might intersect with W/SC.
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Affiliation(s)
- Sabrina Chin
- Noble Research Institute LLC, 2510 Sam Noble Parkway, Ardmore, Oklahoma 73401, USA
| | - Taegun Kwon
- Noble Research Institute LLC, 2510 Sam Noble Parkway, Ardmore, Oklahoma 73401, USA
| | - Bibi Rafeiza Khan
- Noble Research Institute LLC, 2510 Sam Noble Parkway, Ardmore, Oklahoma 73401, USA
| | - J. Alan Sparks
- Noble Research Institute LLC, 2510 Sam Noble Parkway, Ardmore, Oklahoma 73401, USA
| | - Eileen L. Mallery
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907, USA
| | - Daniel B. Szymanski
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907, USA
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907, USA
| | - Elison B. Blancaflor
- Noble Research Institute LLC, 2510 Sam Noble Parkway, Ardmore, Oklahoma 73401, USA
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7
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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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8
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Burtscher WP, List MA, Payton AC, McDaniel SF, Carey SB. Area from image analyses accurately estimates dry-weight biomass of juvenile tissue from the moss Ceratodon purpureus. APPLICATIONS IN PLANT SCIENCES 2021; 9:e11418. [PMID: 33968498 PMCID: PMC8085951 DOI: 10.1002/aps3.11418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 04/02/2021] [Indexed: 06/12/2023]
Abstract
PREMISE Mosses have long served as models for studying many areas of plant biology. Investigators have used two-dimensional measurements of juvenile growth from photographs as a surrogate for dry-weight biomass. The relationship between area and biomass, however, has not been critically evaluated. METHODS Here we grew axenic tissue cultures of 10 Ceratodon purpureus isolates to study the relationship between these parameters. We measured area and biomass on replicate cultures with two distinct starting inoculum sizes each week for three weeks. We then examined the correlation between area and biomass as well as the influence of variation in inoculum size on both parameters. RESULTS We found a strong correlation between area and biomass after two weeks of growth. Furthermore, we found inoculum size affected biomass during the first week of growth but not in subsequent weeks and inoculum size had no detectable effect on area. DISCUSSION These analyses provide experimental confirmation that area is a suitable proxy for biomass and provide clear guidelines for when inoculum size variation may affect downstream growth estimates.
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Affiliation(s)
| | - Marna A. List
- Department of BiologyUniversity of FloridaGainesvilleFlorida32611USA
| | - Adam C. Payton
- Department of BiologyUniversity of FloridaGainesvilleFlorida32611USA
| | | | - Sarah B. Carey
- Department of BiologyUniversity of FloridaGainesvilleFlorida32611USA
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9
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Rathgeb U, Chen M, Buron F, Feddermann N, Schorderet M, Raisin A, Häberli GY, Marc-Martin S, Keller J, Delaux PM, Schaefer DG, Reinhardt D. VAPYRIN-like is required for development of the moss Physcomitrella patens. Development 2020; 147:dev.184762. [DOI: 10.1242/dev.184762] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 04/19/2020] [Indexed: 12/28/2022]
Abstract
The VAPYRIN (VPY) gene in Medicago truncatula and Petunia hybrida is required for arbuscular mycorrhizal (AM) symbiosis. The moss Physcomitrella patens has a close homologue (VPY-like, VPYL), although it does not form AM. Here, we explore the phylogeny of VPY and VPYL in land plants, and we study the expression and developmental function of VPYL in P. patens. We show that PpVPYL is expressed primarily in the protonema, the early filamentous stage of moss development, and later in rhizoids arising from the leafy gametophores and in adult phyllids. Knockout mutants have specific phenotypes in branching of the protonema and in cell division of the leaves (phyllids) in gametophores. The mutants are responsive to auxin and strigolactone, which are involved in the regulation of protonemal branching, indicating that the mutants are not affected in hormonal signaling. Taken together, these results suggest that PpVPYL exerts negative regulation of protonemal branching and of cell division in phyllids. We discuss VPY and VPYL phylogeny and function in land plants in the context of AM symbiosis in angiosperms, and of development in the moss.
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Affiliation(s)
- Ursina Rathgeb
- Dept. of Biology, University of Fribourg, Fribourg, Switzerland
| | - Min Chen
- Dept. of Biology, University of Fribourg, Fribourg, Switzerland
| | - Flavien Buron
- Dept. of Biology, University of Fribourg, Fribourg, Switzerland
| | | | | | - Axelle Raisin
- Dept. of Biology, University of Fribourg, Fribourg, Switzerland
| | | | | | - Jean Keller
- Laboratoire de Recherche en Sciences Végétales, Université de Toulouse, CNRS, Auzeville, Castanet-Tolosan, France
| | - Pierre-Marc Delaux
- Laboratoire de Recherche en Sciences Végétales, Université de Toulouse, CNRS, Auzeville, Castanet-Tolosan, France
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10
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Le Bail A, Schulmeister S, Perroud PF, Ntefidou M, Rensing SA, Kost B. Analysis of the Localization of Fluorescent PpROP1 and PpROP-GEF4 Fusion Proteins in Moss Protonemata Based on Genomic "Knock-In" and Estradiol-Titratable Expression. FRONTIERS IN PLANT SCIENCE 2019; 10:456. [PMID: 31031790 PMCID: PMC6473103 DOI: 10.3389/fpls.2019.00456] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 03/26/2019] [Indexed: 05/26/2023]
Abstract
Tip growth of pollen tubes, root hairs, and apical cells of moss protonemata is controlled by ROP (Rho of plants) GTPases, which were shown to accumulate at the apical plasma membrane of these cells. However, most ROP localization patterns reported in the literature are based on fluorescent protein tagging and need to be interpreted with caution, as ROP fusion proteins were generally overexpressed at undefined levels, in many cases without assessing effects on tip growth. ROP-GEFs, important regulators of ROP activity, were also described to accumulate at the apical plasma membrane during tip growth. However, to date only the localization of fluorescent ROP-GEF fusion proteins strongly overexpressed using highly active promoters have been investigated. Here, the intracellular distributions of fluorescent PpROP1 and PpROP-GEF4 fusion proteins expressed at essentially endogenous levels in apical cells of Physcomitrella patens "knock-in" protonemata were analyzed. Whereas PpROP-GEF4 was found to associate with a small apical plasma membrane domain, PpROP1 expression was below the detection limit. Estradiol-titratable expression of a fluorescent PpROP1 fusion protein at the lowest detectable level, at which plant development was only marginally affected, was therefore employed to show that PpROP1 also accumulates at the apical plasma membrane, although within a substantially larger domain. Interestingly, RNA-Seq data indicated that the majority of all genes active in protonemata are expressed at lower levels than PpROP1, suggesting that estradiol-titratable expression may represent an important alternative to "knock-in" based analysis of the intracellular distribution of fluorescent fusion proteins in protonemal cells.
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Affiliation(s)
- Aude Le Bail
- Cell Biology, Department of Biology, Friedrich–Alexander University Erlangen–Nürnberg, Erlangen, Germany
| | - Sylwia Schulmeister
- Cell Biology, Department of Biology, Friedrich–Alexander University Erlangen–Nürnberg, Erlangen, Germany
| | | | - Maria Ntefidou
- Cell Biology, Department of Biology, Friedrich–Alexander University Erlangen–Nürnberg, Erlangen, Germany
| | - Stefan A. Rensing
- Plant Cell Biology, Faculty of Biology, Philipps University of Marburg, Marburg, Germany
| | - Benedikt Kost
- Cell Biology, Department of Biology, Friedrich–Alexander University Erlangen–Nürnberg, Erlangen, Germany
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11
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Perroud PF, Meyberg R, Rensing SA. Physcomitrella patens Reute mCherry as a tool for efficient crossing within and between ecotypes. PLANT BIOLOGY (STUTTGART, GERMANY) 2019; 21 Suppl 1:143-149. [PMID: 29772086 DOI: 10.1111/plb.12840] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 05/09/2018] [Indexed: 05/21/2023]
Abstract
Physcomitrella patens is a monoecious moss that is predominantly selfing in the wild. Laboratory crossing techniques have been established and crosses between the sequenced Gransden ecotype and the genetically divergent Villersexel ecotype were used for genetic mapping. The recently introduced ecotype Reute has a high fertility rate and is genetically more closely related to the Gransden ecotype than the Villersexel ecotype. Reute sexual reproduction phenology is similar to Gransden, which should allow successful crossing. Using the Reute ecotype and an existing Gransden mutant as a test case, we applied a normalised crossing approach to demonstrate crossing potential between these ecotypes. Also, using a standard transformation approach, we generated Reute fluorescent strains expressing mCherry that allow an easy detection of crossed offspring (sporophyte). We show that Reute can be successfully crossed with a self-infertile DR5:DsRed2 mutant generated in the Gransden background. Using newly established Reute fluorescent strains, we show that they can efficiently fertilise Reute as well as Gransden wild type. The resulting progeny display Mendelian 1:1 segregation of the fluorescent marker(s), demonstrating the suitability of such strains for genetic crossing. Overall our results demonstrate that Reute is highly suitable for genetic crossing. The Reute mCherry strain can be used as a suitable background for offspring selection after crossing.
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Affiliation(s)
- P-F Perroud
- Plant Cell Biology, Faculty of Biology, University of Marburg, Marburg, Germany
| | - R Meyberg
- Plant Cell Biology, Faculty of Biology, University of Marburg, Marburg, Germany
| | - S A Rensing
- Plant Cell Biology, Faculty of Biology, University of Marburg, Marburg, Germany
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
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12
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Yanagisawa M, Alonso JM, Szymanski DB. Microtubule-Dependent Confinement of a Cell Signaling and Actin Polymerization Control Module Regulates Polarized Cell Growth. Curr Biol 2018; 28:2459-2466.e4. [DOI: 10.1016/j.cub.2018.05.076] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 04/23/2018] [Accepted: 05/24/2018] [Indexed: 10/28/2022]
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13
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Bascom CS, Hepler PK, Bezanilla M. Interplay between Ions, the Cytoskeleton, and Cell Wall Properties during Tip Growth. PLANT PHYSIOLOGY 2018; 176:28-40. [PMID: 29138353 PMCID: PMC5761822 DOI: 10.1104/pp.17.01466] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Accepted: 11/05/2017] [Indexed: 05/08/2023]
Abstract
Tip growth is a focused and tightly regulated apical explosion that depends on the interconnected activities of ions, the cytoskeleton, and the cell wall.
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Affiliation(s)
- Carlisle S Bascom
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire 03755
- Plant Biology Graduate Program, University of Massachusetts, Amherst, Massachusetts 01002
| | - Peter K Hepler
- Biology Department, University of Massachusetts, Amherst, Massachusetts 01002
| | - Magdalena Bezanilla
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire 03755
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Szymanski D, Staiger CJ. The Actin Cytoskeleton: Functional Arrays for Cytoplasmic Organization and Cell Shape Control. PLANT PHYSIOLOGY 2018; 176:106-118. [PMID: 29192029 PMCID: PMC5761824 DOI: 10.1104/pp.17.01519] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 11/29/2017] [Indexed: 05/18/2023]
Abstract
Functionally distinct actin filament arrays cluster organelles and define cellular scale flow patterns for secretion.
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Affiliation(s)
- Dan Szymanski
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907
- Department of Agronomy, Purdue University, West Lafayette, Indiana 47907
| | - Christopher J Staiger
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907
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Rawat A, Brejšková L, Hála M, Cvrčková F, Žárský V. The Physcomitrella patens exocyst subunit EXO70.3d has distinct roles in growth and development, and is essential for completion of the moss life cycle. THE NEW PHYTOLOGIST 2017; 216:438-454. [PMID: 28397275 DOI: 10.1111/nph.14548] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 02/24/2017] [Indexed: 05/28/2023]
Abstract
The exocyst, an evolutionarily conserved secretory vesicle-tethering complex, spatially controls exocytosis and membrane turnover in fungi, metazoans and plants. The exocyst subunit EXO70 exists in multiple paralogs in land plants, forming three conserved clades with assumed distinct roles. Here we report functional analysis of the first moss exocyst subunit to be studied, Physcomitrella patens PpEXO70.3d (Pp1s97_91V6), from the, as yet, poorly characterized EXO70.3 clade. Following phylogenetic analysis to confirm the presence of three ancestral land plant EXO70 clades outside angiosperms, we prepared and phenotypically characterized loss-of-function Ppexo70.3d mutants and localized PpEXO70.3d in vivo using green fluorescent protein-tagged protein expression. Disruption of PpEXO70.3d caused pleiotropic cell elongation and differentiation defects in protonemata, altered response towards exogenous auxin, increased endogenous IAA concentrations, along with defects in bud and gametophore development. During mid-archegonia development, an abnormal egg cell is formed and subsequently collapses, resulting in mutant sterility. Mutants exhibited altered cell wall and cuticle deposition, as well as compromised cytokinesis, consistent with the protein localization to the cell plate. Despite some functional redundancy allowing survival of moss lacking PpEXO70.3d, this subunit has an essential role in the moss life cycle, indicating sub-functionalization within the moss EXO70 family.
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Affiliation(s)
- Anamika Rawat
- Laboratory of Cell Morphogenesis, Department of Experimental Plant Biology, Faculty of Science, Charles University, Viničná 5, 128 44, Prague 2, Czech Republic
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic, 165 02, Prague 6, Czech Republic
| | - Lucie Brejšková
- Laboratory of Cell Morphogenesis, Department of Experimental Plant Biology, Faculty of Science, Charles University, Viničná 5, 128 44, Prague 2, Czech Republic
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic, 165 02, Prague 6, Czech Republic
| | - Michal Hála
- Laboratory of Cell Morphogenesis, Department of Experimental Plant Biology, Faculty of Science, Charles University, Viničná 5, 128 44, Prague 2, Czech Republic
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic, 165 02, Prague 6, Czech Republic
| | - Fatima Cvrčková
- Laboratory of Cell Morphogenesis, Department of Experimental Plant Biology, Faculty of Science, Charles University, Viničná 5, 128 44, Prague 2, Czech Republic
| | - Viktor Žárský
- Laboratory of Cell Morphogenesis, Department of Experimental Plant Biology, Faculty of Science, Charles University, Viničná 5, 128 44, Prague 2, Czech Republic
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic, 165 02, Prague 6, Czech Republic
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16
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Ako AE, Perroud PF, Innocent J, Demko V, Olsen OA, Johansen W. An intragenic mutagenesis strategy in Physcomitrella patens to preserve intron splicing. Sci Rep 2017; 7:5111. [PMID: 28698618 PMCID: PMC5505980 DOI: 10.1038/s41598-017-05309-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Accepted: 05/26/2017] [Indexed: 12/27/2022] Open
Abstract
Gene targeting is a powerful reverse genetics technique for site-specific genome modification. Intrinsic homologous recombination in the moss Physcomitrella patens permits highly effective gene targeting, a characteristic that makes this organism a valuable model for functional genetics. Functional characterization of domains located within a multi-domain protein depends on the ability to generate mutants harboring genetic modifications at internal gene positions while maintaining the reading-frames of the flanking exons. In this study, we designed and evaluated different gene targeting constructs for targeted gene manipulation of sequences corresponding to internal domains of the DEFECTIVE KERNEL1 protein in Physcomitrella patens. Our results show that gene targeting-associated mutagenesis of introns can have adverse effects on splicing, corrupting the normal reading frame of the transcript. We show that successful genetic modification of internal sequences of multi-exon genes depends on gene-targeting strategies which insert the selection marker cassette into the 5' end of the intron and preserve the nucleotide sequence of the targeted intron.
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Affiliation(s)
- Ako Eugene Ako
- Inland Norway University of Applied Sciences, Holsetgata 31, N-2318, Hamar, Norway
| | - Pierre-François Perroud
- Philipps University Marburg, Plant Cell Biology II, Karl-von-Frisch-Str. 8, 35043, Marburg, Germany
| | - Joseph Innocent
- Inland Norway University of Applied Sciences, Holsetgata 31, N-2318, Hamar, Norway
| | - Viktor Demko
- Norwegian University of Life Sciences, P.O. Box 5003, N-1432, As, Norway
| | - Odd-Arne Olsen
- Norwegian University of Life Sciences, P.O. Box 5003, N-1432, As, Norway.
| | - Wenche Johansen
- Inland Norway University of Applied Sciences, Holsetgata 31, N-2318, Hamar, Norway.
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17
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Bascom CS, Wu SZ, Nelson K, Oakey J, Bezanilla M. Long-Term Growth of Moss in Microfluidic Devices Enables Subcellular Studies in Development. PLANT PHYSIOLOGY 2016; 172:28-37. [PMID: 27406170 PMCID: PMC5074637 DOI: 10.1104/pp.16.00879] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 07/08/2016] [Indexed: 05/20/2023]
Abstract
Key developmental processes that occur on the subcellular and cellular level or occur in occluded tissues are difficult to access, let alone image and analyze. Recently, culturing living samples within polydimethylsiloxane (PDMS) microfluidic devices has facilitated the study of hard-to-reach developmental events. Here, we show that an early diverging land plant, Physcomitrella patens, can be continuously cultured within PDMS microfluidic chambers. Because the PDMS chambers are bonded to a coverslip, it is possible to image P. patens development at high resolution over long time periods. Using PDMS chambers, we report that wild-type protonemal tissue grows at the same rate as previously reported for growth on solid medium. Using long-term imaging, we highlight key developmental events, demonstrate compatibility with high-resolution confocal microscopy, and obtain growth rates for a slow-growing mutant. By coupling the powerful genetic tools available to P. patens with long-term growth and imaging provided by PDMS microfluidic chambers, we demonstrate the capability to study cellular and subcellular developmental events in plants directly and in real time.
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Affiliation(s)
- Carlisle S Bascom
- Department of Biology (C.S.B., S.-Z.W., M.B.) and Plant Biology Graduate Program (C.S.B.), University of Massachusetts, Amherst, Massachusetts 01003; andDepartment of Chemical Engineering (K.N., J.O.) and Department of Molecular Biology (K.N.), University of Wyoming, Laramie, Wyoming 82071
| | - Shu-Zon Wu
- Department of Biology (C.S.B., S.-Z.W., M.B.) and Plant Biology Graduate Program (C.S.B.), University of Massachusetts, Amherst, Massachusetts 01003; andDepartment of Chemical Engineering (K.N., J.O.) and Department of Molecular Biology (K.N.), University of Wyoming, Laramie, Wyoming 82071
| | - Katherine Nelson
- Department of Biology (C.S.B., S.-Z.W., M.B.) and Plant Biology Graduate Program (C.S.B.), University of Massachusetts, Amherst, Massachusetts 01003; andDepartment of Chemical Engineering (K.N., J.O.) and Department of Molecular Biology (K.N.), University of Wyoming, Laramie, Wyoming 82071
| | - John Oakey
- Department of Biology (C.S.B., S.-Z.W., M.B.) and Plant Biology Graduate Program (C.S.B.), University of Massachusetts, Amherst, Massachusetts 01003; andDepartment of Chemical Engineering (K.N., J.O.) and Department of Molecular Biology (K.N.), University of Wyoming, Laramie, Wyoming 82071
| | - Magdalena Bezanilla
- Department of Biology (C.S.B., S.-Z.W., M.B.) and Plant Biology Graduate Program (C.S.B.), University of Massachusetts, Amherst, Massachusetts 01003; andDepartment of Chemical Engineering (K.N., J.O.) and Department of Molecular Biology (K.N.), University of Wyoming, Laramie, Wyoming 82071
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18
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Schuessele C, Hoernstein SNW, Mueller SJ, Rodriguez-Franco M, Lorenz T, Lang D, Igloi GL, Reski R. Spatio-temporal patterning of arginyl-tRNA protein transferase (ATE) contributes to gametophytic development in a moss. THE NEW PHYTOLOGIST 2016; 209:1014-1027. [PMID: 26428055 DOI: 10.1111/nph.13656] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 08/14/2015] [Indexed: 06/05/2023]
Abstract
The importance of the arginyl-tRNA protein transferase (ATE), the enzyme mediating post-translation arginylation of proteins in the N-end rule degradation (NERD) pathway of protein stability, was analysed in Physcomitrella patens and compared to its known functions in other eukaryotes. We characterize ATE:GUS reporter lines as well as ATE mutants in P. patens to study the impact and function of arginylation on moss development and physiology. ATE protein abundance is spatially and temporally regulated in P. patens by hormones and light and is highly abundant in meristematic cells. Further, the amount of ATE transcript is regulated during abscisic acid signalling and downstream of auxin signalling. Loss-of-function mutants exhibit defects at various levels, most severely in developing gametophores, in chloroplast starch accumulation and senescence. Thus, arginylation is necessary for moss gametophyte development, in contrast to the situation in flowering plants. Our analysis further substantiates the conservation of the N-end rule pathway components in land plants and highlights lineage-specific features. We introduce moss as a model system to characterize the role of the NERD pathway as an additional layer of complexity in eukaryotic development.
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Affiliation(s)
- Christian Schuessele
- Plant Biotechnology, Faculty of Biology, University of Freiburg, Schaenzlestr. 1, 79104, Freiburg, Germany
- Institute of Biology 3, Faculty of Biology, University of Freiburg, Schaenzlestr. 1, 79104, Freiburg, Germany
| | - Sebastian N W Hoernstein
- Plant Biotechnology, Faculty of Biology, University of Freiburg, Schaenzlestr. 1, 79104, Freiburg, Germany
- Institute of Biology 3, Faculty of Biology, University of Freiburg, Schaenzlestr. 1, 79104, Freiburg, Germany
| | - Stefanie J Mueller
- Plant Biotechnology, Faculty of Biology, University of Freiburg, Schaenzlestr. 1, 79104, Freiburg, Germany
| | - Marta Rodriguez-Franco
- Cell Biology, Faculty of Biology, University of Freiburg, Schaenzlestr. 1, 79104, Freiburg, Germany
| | - Timo Lorenz
- Plant Biotechnology, Faculty of Biology, University of Freiburg, Schaenzlestr. 1, 79104, Freiburg, Germany
| | - Daniel Lang
- Plant Biotechnology, Faculty of Biology, University of Freiburg, Schaenzlestr. 1, 79104, Freiburg, Germany
| | - Gabor L Igloi
- Institute of Biology 3, Faculty of Biology, University of Freiburg, Schaenzlestr. 1, 79104, Freiburg, Germany
| | - Ralf Reski
- Plant Biotechnology, Faculty of Biology, University of Freiburg, Schaenzlestr. 1, 79104, Freiburg, Germany
- FRIAS - Freiburg Institute for Advanced Studies, University of Freiburg, 79104, Freiburg, Germany
- BIOSS - Centre for Biological Signalling Studies, University of Freiburg, 79104, Freiburg, Germany
- TIP - Trinational Institute for Plant Research, Upper Rhine Valley, 79104, Freiburg, Germany
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19
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Abstract
At first glance, mitosis in plants looks quite different from that in animals. In fact, terrestrial plants have lost the centrosome during evolution, and the mitotic spindle is assembled independently of a strong microtubule organizing center. The phragmoplast is a plant-specific mitotic apparatus formed after anaphase, which expands centrifugally towards the cell cortex. However, the extent to which plant mitosis differs from that of animals at the level of the protein repertoire is uncertain, largely because of the difficulty in the identification and in vivo characterization of mitotic genes of plants. Here, we discuss protocols for mitosis imaging that can be combined with endogenous green fluorescent protein (GFP) tagging or conditional RNA interference (RNAi) in the moss Physcomitrella patens, which is an emergent model plant for cell and developmental biology. This system has potential for use in the high-throughput study of mitosis and other intracellular processes, as is being done with various animal cell lines.
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20
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Burkart GM, Baskin TI, Bezanilla M. A family of ROP proteins that suppresses actin dynamics, and is essential for polarized growth and cell adhesion. J Cell Sci 2015; 128:2553-64. [PMID: 26045445 DOI: 10.1242/jcs.172445] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 05/31/2015] [Indexed: 01/22/2023] Open
Abstract
In plants, the ROP family of small GTPases has been implicated in the polarized growth of tip-growing cells, such as root hairs and pollen tubes; however, most of the data derive from overexpressing ROP genes or constitutively active and dominant-negative isoforms, whereas confirmation by using loss-of-function studies has generally been lacking. Here, in the model moss Physcomitrella patens, we study ROP signaling during tip growth by using a loss-of-function approach based on RNA interference (RNAi) to silence the entire moss ROP family. We find that plants with reduced expression of ROP genes, in addition to failing to initiate tip growth, have perturbed cell wall staining, reduced cell adhesion and have increased actin-filament dynamics. Although plants subjected to RNAi against the ROP family also have reduced microtubule dynamics, this reduction is not specific to loss of ROP genes, as it occurs when actin function is compromised chemically or genetically. Our data suggest that ROP proteins polarize the actin cytoskeleton by suppressing actin-filament dynamics, leading to an increase in actin filaments at the site of polarized secretion.
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Affiliation(s)
- Graham M Burkart
- Department of Biology, University of Massachusetts-Amherst, 611 N. Pleasant Street, Amherst, MA 01003, USA Plant Biology Graduate Program, University of Massachusetts-Amherst, 611 N. Pleasant Street, Amherst, MA 01003, USA
| | - Tobias I Baskin
- Department of Biology, University of Massachusetts-Amherst, 611 N. Pleasant Street, Amherst, MA 01003, USA
| | - Magdalena Bezanilla
- Department of Biology, University of Massachusetts-Amherst, 611 N. Pleasant Street, Amherst, MA 01003, USA
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21
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Perroud PF, Demko V, Johansen W, Wilson RC, Olsen OA, Quatrano RS. Defective Kernel 1 (DEK1) is required for three-dimensional growth in Physcomitrella patens. THE NEW PHYTOLOGIST 2014; 203:794-804. [PMID: 24844771 PMCID: PMC4285852 DOI: 10.1111/nph.12844] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 04/04/2014] [Indexed: 05/18/2023]
Abstract
Orientation of cell division is critical for plant morphogenesis. This is evident in the formation and function of meristems and for morphogenetic transitions. Mosses undergo such transitions: from two-dimensional tip-growing filaments (protonema) to the generation of three-dimensional leaf-like structures (gametophores). The Defective Kernel 1 (DEK1) protein plays a key role in the perception of and/or response to positional cues that specify the formation and function of the epidermal layer in developing seeds of flowering plants. The moss Physcomitrella patens contains the highly conserved DEK1 gene. Using efficient gene targeting, we generated a precise PpDEK1 deletion (∆dek1), which resulted in normal filamentous growth of protonema. Two distinct mutant phenotypes were observed: an excess of buds on the protonema, and abnormal cell divisions in the emerging buds resulting in developmental arrest and the absence of three-dimensional growth. Overexpression of a complete PpDEK1 cDNA, or the calpain domain of PpDEK1 alone, successfully complements both phenotypes. These results in P. patens demonstrate the morphogenetic importance of the DEK1 protein in the control of oriented cell divisions. As it is not for protonema, it will allow dissection of the structure/function relationships of the different domains of DEK1 using gene targeting in null mutant background.
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Affiliation(s)
- Pierre-François Perroud
- Department of Biology, Washington University in St Louis, Campus Box 1137, St Louis, MO, 63130-4899, USA
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22
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Beike AK, von Stackelberg M, Schallenberg-Rüdinger M, Hanke ST, Follo M, Quandt D, McDaniel SF, Reski R, Tan BC, Rensing SA. Molecular evidence for convergent evolution and allopolyploid speciation within the Physcomitrium-Physcomitrella species complex. BMC Evol Biol 2014; 14:158. [PMID: 25015729 PMCID: PMC4227049 DOI: 10.1186/1471-2148-14-158] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 07/04/2014] [Indexed: 11/10/2022] Open
Abstract
Background The moss Physcomitrella patens (Hedw.) Bruch & Schimp. is an important experimental model system for evolutionary-developmental studies. In order to shed light on the evolutionary history of Physcomitrella and related species within the Funariaceae, we analyzed the natural genetic diversity of the Physcomitrium-Physcomitrella species complex. Results Molecular analysis of the nuclear single copy gene BRK1 reveals that three Physcomitrium species feature larger genome sizes than Physcomitrella patens and encode two expressed BRK1 homeologs (polyploidization-derived paralogs), indicating that they may be allopolyploid hybrids. Phylogenetic analyses of BRK1 as well as microsatellite simple sequence repeat (SSR) data confirm a polyphyletic origin for three Physcomitrella lineages. Differences in the conservation of mitochondrial editing sites further support hybridization and cryptic speciation within the Physcomitrium-Physcomitrella species complex. Conclusions We propose a revised classification of the previously described four subspecies of Physcomitrella patens into three distinct species, namely Physcomitrella patens, Physcomitrella readeri and Physcomitrella magdalenae. We argue that secondary reduction of sporophyte complexity in these species is due to the establishment of an ecological niche, namely spores resting in mud and possible spore dispersal by migratory birds. Besides the Physcomitrium-Physcomitrella species complex, the Funariaceae are host to their type species, Funaria hygrometrica, featuring a sporophyte morphology which is more complex. Their considerable developmental variation among closely related lineages and remarkable trait evolution render the Funariaceae an interesting group for evolutionary and genetic research.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Stefan A Rensing
- Faculty of Biology, University of Freiburg, Schänzlestr, 1, 79104 Freiburg, Germany.
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Dangwal M, Kapoor S, Kapoor M. The PpCMT chromomethylase affects cell growth and interacts with the homolog of LIKE HETEROCHROMATIN PROTEIN 1 in the moss Physcomitrella patens. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2014; 77:589-603. [PMID: 24329971 DOI: 10.1111/tpj.12406] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Revised: 11/30/2013] [Accepted: 12/03/2013] [Indexed: 05/06/2023]
Abstract
Chromomethylases (CMTs) are plant-specific cytosine DNA methyltransferases that are involved in maintenance of CpNpG methylation. In seed plants, histone methylation and interaction of CMT with LIKE HETEROCHROMATIN PROTEIN 1 (LHP1) is essential for recruitment of CMT to target sites. LHP1 has been characterized as a putative component of the POLYCOMB REPRESSIVE COMPLEX1 (PRC1) in plants, and functions downstream of PRC2 to maintain genes in repressed state for orchestrated development. In the present study, we show that targeted disruption of PpCMT results in an approximately 50% reduction in global cytosine methylation levels. This affects growth of apical cells, predominantly growth of side branch initials emerging from chloronema cells. In some places, these cells develop thick walls with plasmolyzed cellular contents. Transcript accumulation patterns of genes involved in apical cell extension and metabolism of hemicelluloses, such as xyloglucans, in the primary cell walls decreased many fold in ppcmt mutant lines, as determined by real-time PCR. Using yeast two-hybrid method and bimolecular fluorescence complementation assay, we show that PpCMT and PpLHP1 interact through their chromo domains, while PpLHP1 homodimerizes through its chromo shadow domain. The results presented in this study provide insight into the role of the single chromomethylase, PpCMT, in proliferation of protonema filaments, and shed light on the evolutionary conservation of proteins interacting with these methylases in the early land plant, Physcomitrella patens.
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Affiliation(s)
- Meenakshi Dangwal
- University School of Biotechnology, Guru Gobind Singh Indraprastha University, Sector 16C, Dwarka, New Delhi, 110078, India
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24
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Zimmer AD, Lang D, Buchta K, Rombauts S, Nishiyama T, Hasebe M, Van de Peer Y, Rensing SA, Reski R. Reannotation and extended community resources for the genome of the non-seed plant Physcomitrella patens provide insights into the evolution of plant gene structures and functions. BMC Genomics 2013; 14:498. [PMID: 23879659 PMCID: PMC3729371 DOI: 10.1186/1471-2164-14-498] [Citation(s) in RCA: 136] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Accepted: 07/19/2013] [Indexed: 11/24/2022] Open
Abstract
Background The moss Physcomitrella patens as a model species provides an important reference for early-diverging lineages of plants and the release of the genome in 2008 opened the doors to genome-wide studies. The usability of a reference genome greatly depends on the quality of the annotation and the availability of centralized community resources. Therefore, in the light of accumulating evidence for missing genes, fragmentary gene structures, false annotations and a low rate of functional annotations on the original release, we decided to improve the moss genome annotation. Results Here, we report the complete moss genome re-annotation (designated V1.6) incorporating the increased transcript availability from a multitude of developmental stages and tissue types. We demonstrate the utility of the improved P. patens genome annotation for comparative genomics and new extensions to the cosmoss.org resource as a central repository for this plant “flagship” genome. The structural annotation of 32,275 protein-coding genes results in 8387 additional loci including 1456 loci with known protein domains or homologs in Plantae. This is the first release to include information on transcript isoforms, suggesting alternative splicing events for at least 10.8% of the loci. Furthermore, this release now also provides information on non-protein-coding loci. Functional annotations were improved regarding quality and coverage, resulting in 58% annotated loci (previously: 41%) that comprise also 7200 additional loci with GO annotations. Access and manual curation of the functional and structural genome annotation is provided via the http://www.cosmoss.org model organism database. Conclusions Comparative analysis of gene structure evolution along the green plant lineage provides novel insights, such as a comparatively high number of loci with 5’-UTR introns in the moss. Comparative analysis of functional annotations reveals expansions of moss house-keeping and metabolic genes and further possibly adaptive, lineage-specific expansions and gains including at least 13% orphan genes.
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Affiliation(s)
- Andreas D Zimmer
- Plant Biotechnology, Faculty of Biology, University of Freiburg, Schaenzlestrasse 1, 79104, Freiburg, Germany
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25
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Zhang C, Mallery E, Reagan S, Boyko VP, Kotchoni SO, Szymanski DB. The endoplasmic reticulum is a reservoir for WAVE/SCAR regulatory complex signaling in the Arabidopsis leaf. PLANT PHYSIOLOGY 2013; 162:689-706. [PMID: 23613272 PMCID: PMC3668063 DOI: 10.1104/pp.113.217422] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
During plant cell morphogenesis, signal transduction and cytoskeletal dynamics interact to locally organize the cytoplasm and define the geometry of cell expansion. The WAVE/SCAR (for WASP family verprolin homologous/suppressor of cyclic AMP receptor) regulatory complex (W/SRC) is an evolutionarily conserved heteromeric protein complex. Within the plant kingdom W/SRC is a broadly used effector that converts Rho-of-Plants (ROP)/Rac small GTPase signals into Actin-Related Protein2/3 and actin-dependent growth responses. Although the components and biochemistry of the W/SRC pathway are well understood, a basic understanding of how cells partition W/SRC into active and inactive pools is lacking. In this paper, we report that the endoplasmic reticulum (ER) is an important organelle for W/SRC regulation. We determined that a large intracellular pool of the core W/SRC subunit NAP1, like the known positive regulator of W/SRC, the DOCK family guanine nucleotide-exchange factor SPIKE1 (SPK1), localizes to the surface of the ER. The ER-associated NAP1 is inactive because it displays little colocalization with the actin network, and ER localization requires neither activating signals from SPK1 nor a physical association with its W/SRC-binding partner, SRA1. Our results indicate that in Arabidopsis (Arabidopsis thaliana) leaf pavement cells and trichomes, the ER is a reservoir for W/SRC signaling and may have a key role in the early steps of W/SRC assembly and/or activation.
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26
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Domozych DS, Fujimoto C, LaRue T. Polar Expansion Dynamics in the Plant Kingdom: A Diverse and Multifunctional Journey on the Path to Pollen Tubes. PLANTS (BASEL, SWITZERLAND) 2013; 2:148-73. [PMID: 27137370 PMCID: PMC4844288 DOI: 10.3390/plants2010148] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Revised: 02/24/2013] [Accepted: 03/01/2013] [Indexed: 12/18/2022]
Abstract
Polar expansion is a widespread phenomenon in plants spanning all taxonomic groups from the Charophycean Green Algae to pollen tubes in Angiosperms and Gymnosperms. Current data strongly suggests that many common features are shared amongst cells displaying polar growth mechanics including changes to the structural features of localized regions of the cell wall, mobilization of targeted secretion mechanisms, employment of the actin cytoskeleton for directing secretion and in many cases, endocytosis and coordinated interaction of multiple signal transduction mechanisms prompted by external biotic and abiotic cues. The products of polar expansion perform diverse functions including delivery of male gametes to the egg, absorption, anchorage, adhesion and photo-absorption efficacy. A comparative analysis of polar expansion dynamics is provided with special emphasis on those found in early divergent plants.
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Affiliation(s)
- David S Domozych
- Department of Biology and Skidmore Microscopy Imaging Center, Skidmore College, Saratoga Springs, New York, NY 12866, USA.
| | - Chelsea Fujimoto
- Department of Biology and Skidmore Microscopy Imaging Center, Skidmore College, Saratoga Springs, New York, NY 12866, USA.
| | - Therese LaRue
- Department of Biology and Skidmore Microscopy Imaging Center, Skidmore College, Saratoga Springs, New York, NY 12866, USA.
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27
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Furt F, Liu YC, Bibeau JP, Tüzel E, Vidali L. Apical myosin XI anticipates F-actin during polarized growth of Physcomitrella patens cells. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 73:417-428. [PMID: 23020796 DOI: 10.1111/tpj.12039] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Revised: 09/07/2012] [Accepted: 09/27/2012] [Indexed: 05/28/2023]
Abstract
Tip growth is essential for land colonization by bryophytes, plant sexual reproduction and water and nutrient uptake. Because this specialized form of polarized cell growth requires both a dynamic actin cytoskeleton and active secretion, it has been proposed that the F-actin-associated motor myosin XI is essential for this process. Nevertheless, a spatial and temporal relationship between myosin XI and F-actin during tip growth is not known in any plant cell. Here, we use the highly polarized cells of the moss Physcomitrella patens to show that myosin XI and F-actin localize, in vivo, at the same apical domain and that both signals fluctuate. Surprisingly, phase analysis shows that increase in myosin XI anticipates that of F-actin; in contrast, myosin XI levels at the tip fluctuate in identical phase with a vesicle marker. Pharmacological analysis using a low concentration of the actin polymerization inhibitor latrunculin B showed that the F-actin at the tip can be significantly diminished while myosin XI remains elevated in this region, suggesting that a mechanism exists to cluster myosin XI-associated structures at the cell's apex. In addition, this approach uncovered a mechanism for actin polymerization-dependent motility in the moss cytoplasm, where myosin XI-associated structures seem to anticipate and organize the actin polymerization machinery. From our results, we inferred a model where the interaction between myosin XI-associated vesicular structures and F-actin polymerization-driven motility function at the cell's apex to maintain polarized cell growth. We hypothesize this is a general mechanism for the participation of myosin XI and F-actin in tip growing cells.
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Affiliation(s)
- Fabienne Furt
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, MA 01609, USA
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Yanagisawa M, Zhang C, Szymanski DB. ARP2/3-dependent growth in the plant kingdom: SCARs for life. FRONTIERS IN PLANT SCIENCE 2013; 4:166. [PMID: 23802001 PMCID: PMC3689024 DOI: 10.3389/fpls.2013.00166] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2013] [Accepted: 05/12/2013] [Indexed: 05/18/2023]
Abstract
In the human experience SCARs (suppressor of cAMP receptors) are permanent reminders of past events, not always based on bad decisions, but always those in which an interplay of opposing forces leaves behind a clear record in the form of some permanent watery mark. During plant morphogenesis, SCARs are important proteins that reflect an unusual evolutionary outcome, in which the plant kingdom relies heavily on this single class of actin-related protein (ARP) 2/3 complex activator to dictate the time and place of actin filament nucleation. This unusually simple arrangement may serve as a permanent reminder that cell shape control in plants is fundamentally different from that of crawling cells in mammals that use the power of actin polymerization to define and maintain cell shape. In plant cells, actin filaments indirectly affect cell shape by determining the transport properties of organelles and cargo molecules that modulate the mechanical properties of the wall. It is becoming increasingly clear that polarized bundles of actin filaments operate at whole cell spatial scales to organize the cytoplasm and dictate the patterns of long-distance intracellular transport and secretion. The number of actin-binding proteins and actin filament nucleators that are known to participate in the process of actin network formation are rapidly increasing. In plants, formins and ARP2/3 are two important actin filament nucleators. This review will focus on ARP2/3, and the apparent reliance of most plant species on the SCAR/WAVE (WASP family verprolin homologous) regulatory complex as the sole pathway for ARP2/3 activation.
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Affiliation(s)
| | - Chunhua Zhang
- Department of Botany and Plant Sciences, University of CaliforniaRiverside, CA, USA
| | - Daniel B. Szymanski
- Department of Agronomy, Purdue UniversityWest Lafayette, IN, USA
- Department of Biological Sciences, Purdue UniversityWest Lafayette, IN, USA
- *Correspondence: Daniel B. Szymanski, Department of Agronomy, Purdue University, 1150 Lilly Hall of Life Sciences, West Lafayette, IN 47907-1150, USA e-mail:
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Abstract
Tip growth is employed throughout the plant kingdom. Our understanding of tip growth has benefited from modern tools in molecular genetics, which have enabled the functional characterization of proteins mediating tip growth. Here we first discuss the evolutionary role of tip growth in land plants and then describe the prominent model tip-growth systems, elaborating on some advantages and disadvantages of each. Next we review the organization of tip-growing cells, the role of the cytoskeleton, and recent developments concerning the physiological basis of tip growth. Finally, we review advances in the understanding of the extracellular signals that are known to guide tip-growing cells.
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Affiliation(s)
- Caleb M Rounds
- Department of Biological Sciences, Mount Holyoke College, South Hadley, MA 01075, USA
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Bonhomme S, Nogué F, Rameau C, Schaefer DG. Usefulness of Physcomitrella patens for studying plant organogenesis. Methods Mol Biol 2013; 959:21-43. [PMID: 23299666 DOI: 10.1007/978-1-62703-221-6_2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
In this chapter, we review the main organogenesis features and associated regulation processes of the moss Physcomitrella patens (P. patens), the model plant for the Bryophytes. We highlight how the study of this descendant of the earliest plant species that colonized earth, brings useful keys to understand the mechanisms that determine and control both vascular and non vascular plants organogenesis. Despite its simple morphogenesis pattern, P. patens still requires the fine tuning of organogenesis regulators, including hormone signalling, common to the whole plant kingdom, and which study is facilitated by a high number of molecular tools, among which the powerful possibility of gene targeting/replacement. The recent discovery of moss cells reprogramming capacity completes the picture of an excellent model for studying plant organogenesis.
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Affiliation(s)
- Sandrine Bonhomme
- Institut Jean-Pierre Bourgin, UMR1318 INRA-AgroParisTech, INRA Centre de Versailles-Grignon, Versailles, France.
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31
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Zhang C, Mallery EL, Szymanski DB. ARP2/3 localization in Arabidopsis leaf pavement cells: a diversity of intracellular pools and cytoskeletal interactions. FRONTIERS IN PLANT SCIENCE 2013; 4:238. [PMID: 23874346 PMCID: PMC3709099 DOI: 10.3389/fpls.2013.00238] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Accepted: 06/16/2013] [Indexed: 05/03/2023]
Abstract
In plant cells the actin cytoskeleton adopts many configurations, but is best understood as an unstable, interconnected track that rearranges to define the patterns of long distance transport of organelles during growth. Actin filaments do not form spontaneously; instead filament nucleators, such as the evolutionarily conserved actin-related protein (ARP) 2/3 complex, can efficiently generate new actin filament networks when in a fully activated state. A growing number of genetic experiments have shown that ARP2/3 is necessary for morphogenesis in processes that range from tip growth during root nodule formation to the diffuse polarized growth of leaf trichomes and pavement cells. Although progress has been rapid in the identification of proteins that function in series to positively regulate ARP2/3, less has been learned about the actual function of ARP2/3 in cells. In this paper, we analyze the localization of ARP2/3 in Arabidopsis leaf pavement cells. We detect a pool of ARP2/3 in the nucleus, and also find that ARP2/3 is efficiently and specifically clustered on multiple organelle surfaces and associates with both the actin filament and microtubule cytoskeletons. Our mutant analyses and ARP2/3 and actin double labeling experiments indicate that the clustering of ARP2/3 on organelle surfaces and an association with actin bundles does not necessarily reflect an active pool of ARP2/3, and instead most of the complex appears to exist as a latent organelle-associated pool.
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Affiliation(s)
- Chunhua Zhang
- Department of Agronomy, Purdue UniversityWest Lafayette, IN, USA
| | | | - Daniel B. Szymanski
- Department of Agronomy, Purdue UniversityWest Lafayette, IN, USA
- Department of Biology, Purdue UniversityWest Lafayette, IN, USA
- *Correspondence: Daniel B. Szymanski, Department of Agronomy, Purdue University, Lily Hall of Life Sciences, 915 West State Street, West Lafayette, IN 47907-2054, USA e-mail:
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Vidali L, Bezanilla M. Physcomitrella patens: a model for tip cell growth and differentiation. CURRENT OPINION IN PLANT BIOLOGY 2012; 15:625-31. [PMID: 23022392 DOI: 10.1016/j.pbi.2012.09.008] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Revised: 09/01/2012] [Accepted: 09/04/2012] [Indexed: 05/25/2023]
Abstract
The moss Physcomitrella patens has emerged as an excellent model system owing to its amenability to reverse genetics. The moss gametophyte has three filamentous tissues that grow by tip growth: chloronemata, caulonemata, and rhizoids. Because establishment of the moss plant relies on this form of growth, it is particularly suited for dissecting the molecular basis of tip growth. Recent studies demonstrate that a core set of actin cytoskeletal proteins is essential for tip growth. Additional actin cytoskeletal components are required for modulating growth to produce caulonemata and rhizoids. Differentiation into these cell types has previously been linked to auxin, light and nutrients. Recent studies have identified that core auxin signaling components as well as transcription factors that respond to auxin or nutrient levels are required for tip-growing cell differentiation. Future studies may establish a connection between the actin cytoskeleton and auxin or nutrient-induced cell differentiation.
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Affiliation(s)
- Luis Vidali
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, MA 01609, United States
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Domozych DS. The quest for four-dimensional imaging in plant cell biology: it's just a matter of time. ANNALS OF BOTANY 2012; 110:461-74. [PMID: 22628381 PMCID: PMC3394652 DOI: 10.1093/aob/mcs107] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Accepted: 04/04/2012] [Indexed: 05/22/2023]
Abstract
BACKGROUND Analysis of plant cell dynamics over time, or four-dimensional imaging (4-DI), represents a major goal of plant science. The ability to resolve structures in the third dimension within the cell or tissue during developmental events or in response to environmental or experimental stresses (i.e. 4-DI) is critical to our understanding of gene expression, post-expression modulations of macromolecules and sub-cellular system interactions. SCOPE Microscopy-based technologies have been profoundly integral to this type of investigation, and new and refined microscopy technologies now allow for the visualization of cell dynamics with unprecedented resolution, contrast and experimental versatility. However, certain realities of light and electron microscopy, choice of specimen and specimen preparation techniques limit the scope of readily attaining 4-DI. Today, the plant microscopist must use a combinatorial strategy whereby multiple microscopy-based investigations are used. Modern fluorescence, confocal laser scanning, transmission electron and scanning electron microscopy provide effective conduits for synthesizing data detailing live cell dynamics and highly resolved snapshots of specific cell structures that will ultimately lead to 4-DI. This review provides a synopsis of such technologies available.
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Affiliation(s)
- David S Domozych
- Department of Biology and Skidmore Microscopy Imaging Center, Skidmore College, Saratoga Springs, NY 12866, USA.
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Pei W, Du F, Zhang Y, He T, Ren H. Control of the actin cytoskeleton in root hair development. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2012; 187:10-8. [PMID: 22404828 DOI: 10.1016/j.plantsci.2012.01.008] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2011] [Revised: 01/18/2012] [Accepted: 01/19/2012] [Indexed: 05/09/2023]
Abstract
The development of root hair includes four stages: bulge site selection, bulge formation, tip growth, and maturation. The actin cytoskeleton is involved in all of these stages and is organized into distinct arrangements in the different stages. In addition to the actin configuration, actin isoforms also play distinct roles in the different stages. The actin cytoskeleton is regulated by actin-binding proteins, such as formin, Arp2/3 complex, profilin, actin depolymerizing factor, and villin. Some upstream signals, i.e. calcium, phospholipids, and small GTPase regulate the activity of these actin-binding proteins to produce the proper actin configuration. We constructed a working model on how the actin cytoskeleton is controlled by actin-binding proteins and upstream signaling in root hair development based on the current literature: at the tip of hairs, actin polymerization appears to be facilitated by Arp2/3 complex that is activated by small GTPase, and profilin that is regulated by phosphatidylinositol 4,5-bisphosphate. Meanwhile, actin depolymerization and turnover are likely mediated by villin and actin depolymerizing factor, which are stimulated by calcium. At the shank, actin cables are produced by formin and villin. Under the complicated interaction, the actin cytoskeleton is controlled spatially and temporally during root hair development.
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Affiliation(s)
- Weike Pei
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education and College of Life Science, Beijing Normal University, Beijing 100875, China
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Dyachok J, Zhu L, Liao F, He J, Huq E, Blancaflor EB. SCAR mediates light-induced root elongation in Arabidopsis through photoreceptors and proteasomes. THE PLANT CELL 2011; 23:3610-26. [PMID: 21972261 PMCID: PMC3229138 DOI: 10.1105/tpc.111.088823] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Revised: 09/09/2011] [Accepted: 09/17/2011] [Indexed: 05/18/2023]
Abstract
The ARP2/3 complex, a highly conserved nucleator of F-actin, and its activator, the SCAR complex, are essential for growth in plants and animals. In this article, we present a pathway through which roots of Arabidopsis thaliana directly perceive light to promote their elongation. The ARP2/3-SCAR complex and the maintenance of longitudinally aligned F-actin arrays are crucial components of this pathway. The involvement of the ARP2/3-SCAR complex in light-regulated root growth is supported by our finding that mutants of the SCAR complex subunit BRK1/HSPC300, or other individual subunits of the ARP2/3-SCAR complex, showed a dramatic inhibition of root elongation in the light, which mirrored reduced growth of wild-type roots in the dark. SCAR1 degradation in dark-grown wild-type roots by constitutive photomorphogenic 1 (COP1) E3 ligase and 26S proteasome accompanied the loss of longitudinal F-actin and reduced root growth. Light perceived by the root photoreceptors, cryptochrome and phytochrome, suppressed COP1-mediated SCAR1 degradation. Taken together, our data provide a biochemical explanation for light-induced promotion of root elongation by the ARP2/3-SCAR complex.
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Affiliation(s)
- Julia Dyachok
- Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401
| | - Ling Zhu
- Section of Molecular Cell and Developmental Biology and the Institute for Cellular and Molecular Biology, University of Texas, Austin, Texas 78712
| | - Fuqi Liao
- Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401
| | - Ji He
- Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401
| | - Enamul Huq
- Section of Molecular Cell and Developmental Biology and the Institute for Cellular and Molecular Biology, University of Texas, Austin, Texas 78712
| | - Elison B. Blancaflor
- Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401
- Address correspondence to
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Agrawal GK, Bourguignon J, Rolland N, Ephritikhine G, Ferro M, Jaquinod M, Alexiou KG, Chardot T, Chakraborty N, Jolivet P, Doonan JH, Rakwal R. Plant organelle proteomics: collaborating for optimal cell function. MASS SPECTROMETRY REVIEWS 2011; 30:772-853. [PMID: 21038434 DOI: 10.1002/mas.20301] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2009] [Revised: 02/02/2010] [Accepted: 02/02/2010] [Indexed: 05/10/2023]
Abstract
Organelle proteomics describes the study of proteins present in organelle at a particular instance during the whole period of their life cycle in a cell. Organelles are specialized membrane bound structures within a cell that function by interacting with cytosolic and luminal soluble proteins making the protein composition of each organelle dynamic. Depending on organism, the total number of organelles within a cell varies, indicating their evolution with respect to protein number and function. For example, one of the striking differences between plant and animal cells is the plastids in plants. Organelles have their own proteins, and few organelles like mitochondria and chloroplast have their own genome to synthesize proteins for specific function and also require nuclear-encoded proteins. Enormous work has been performed on animal organelle proteomics. However, plant organelle proteomics has seen limited work mainly due to: (i) inter-plant and inter-tissue complexity, (ii) difficulties in isolation of subcellular compartments, and (iii) their enrichment and purity. Despite these concerns, the field of organelle proteomics is growing in plants, such as Arabidopsis, rice and maize. The available data are beginning to help better understand organelles and their distinct and/or overlapping functions in different plant tissues, organs or cell types, and more importantly, how protein components of organelles behave during development and with surrounding environments. Studies on organelles have provided a few good reviews, but none of them are comprehensive. Here, we present a comprehensive review on plant organelle proteomics starting from the significance of organelle in cells, to organelle isolation, to protein identification and to biology and beyond. To put together such a systematic, in-depth review and to translate acquired knowledge in a proper and adequate form, we join minds to provide discussion and viewpoints on the collaborative nature of organelles in cell, their proper function and evolution.
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Affiliation(s)
- Ganesh Kumar Agrawal
- Research Laboratory for Biotechnology and Biochemistry (RLABB), P.O. Box 13265, Sanepa, Kathmandu, Nepal.
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Wu SZ, Ritchie JA, Pan AH, Quatrano RS, Bezanilla M. Myosin VIII regulates protonemal patterning and developmental timing in the moss Physcomitrella patens. MOLECULAR PLANT 2011; 4:909-21. [PMID: 21873296 DOI: 10.1093/mp/ssr068] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Plants have two classes of myosins. While recent work has focused on class XI myosins showing that myosin XI is responsible for organelle motility and cytoplasmic streaming, much less is known about the role of myosin VIII in plant growth and development. We have used a combination of RNAi and insertional knockouts to probe myosin VIII function in the moss Physcomitrella patens. We isolated Δmyo8ABCDE plants demonstrating that myosin VIII is not required for plant viability. However, myosin VIII mutants are smaller than wild-type plants in part due to a defect in cell size. Additionally, Δmyo8ABCDE plants produce more side branches and form gametophores much earlier than wild-type plants. In the absence of nutrient media, Δmyo8ABCDE plants exhibit significant protonemal patterning defects, including highly curved protonemal filaments, morphologically defective side branches, as well as an increase in the number of branches. Exogenous auxin partially rescues protonemal defects in Δmyo8ABCDE plants grown in the absence of nutrients. This result, together with defects in protonemal branching, smaller caulonemal cells, and accelerated development in the Δmyo8ABCDE plants, suggests that myosin VIII is involved in hormone homeostasis in P. patens.
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Affiliation(s)
- Shu-Zon Wu
- Department of Biology, University of Massachusetts, Amherst, MA 01003, USA
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38
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Ishikawa M, Murata T, Sato Y, Nishiyama T, Hiwatashi Y, Imai A, Kimura M, Sugimoto N, Akita A, Oguri Y, Friedman WE, Hasebe M, Kubo M. Physcomitrella cyclin-dependent kinase A links cell cycle reactivation to other cellular changes during reprogramming of leaf cells. THE PLANT CELL 2011; 23:2924-38. [PMID: 21862705 PMCID: PMC3180801 DOI: 10.1105/tpc.111.088005] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
During regeneration, differentiated plant cells can be reprogrammed to produce stem cells, a process that requires coordination of cell cycle reactivation with acquisition of other cellular characteristics. However, the factors that coordinate the two functions during reprogramming have not been determined. Here, we report a link between cell cycle reactivation and the acquisition of new cell-type characteristics through the activity of cyclin-dependent kinase A (CDKA) during reprogramming in the moss Physcomitrella patens. Excised gametophore leaf cells of P. patens are readily reprogrammed, initiate tip growth, and form chloronema apical cells with stem cell characteristics at their first cell division. We found that leaf cells facing the cut undergo CDK activation along with induction of a D-type cyclin, tip growth, and transcriptional activation of protonema-specific genes. A DNA synthesis inhibitor, aphidicolin, inhibited cell cycle progression but prevented neither tip growth nor protonemal gene expression, indicating that cell cycle progression is not required for acquisition of protonema cell-type characteristics. By contrast, treatment with a CDK inhibitor or induction of dominant-negative CDKA;1 protein inhibited not only cell cycle progression but also tip growth and protonemal gene expression. These findings indicate that cell cycle progression is coordinated with other cellular changes by the concomitant regulation through CDKA;1.
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Affiliation(s)
- Masaki Ishikawa
- Exploratory Research for Advanced Technology, Japan Science and Technology Agency, Okazaki 444-8585, Japan
| | - Takashi Murata
- National Institute for Basic Biology, Okazaki 444-8585, Japan
- School of Life Science, Graduate University for Advanced Studies, Okazaki 444-8585, Japan
| | - Yoshikatsu Sato
- Exploratory Research for Advanced Technology, Japan Science and Technology Agency, Okazaki 444-8585, Japan
| | - Tomoaki Nishiyama
- Exploratory Research for Advanced Technology, Japan Science and Technology Agency, Okazaki 444-8585, Japan
- Advanced Science Research Center, Kanazawa University, Kanazawa 920-0934, Japan
| | - Yuji Hiwatashi
- National Institute for Basic Biology, Okazaki 444-8585, Japan
- School of Life Science, Graduate University for Advanced Studies, Okazaki 444-8585, Japan
| | - Akihiro Imai
- Exploratory Research for Advanced Technology, Japan Science and Technology Agency, Okazaki 444-8585, Japan
- National Institute for Basic Biology, Okazaki 444-8585, Japan
| | - Mina Kimura
- Exploratory Research for Advanced Technology, Japan Science and Technology Agency, Okazaki 444-8585, Japan
| | - Nagisa Sugimoto
- Exploratory Research for Advanced Technology, Japan Science and Technology Agency, Okazaki 444-8585, Japan
| | - Asaka Akita
- Exploratory Research for Advanced Technology, Japan Science and Technology Agency, Okazaki 444-8585, Japan
| | - Yasuko Oguri
- Exploratory Research for Advanced Technology, Japan Science and Technology Agency, Okazaki 444-8585, Japan
| | - William E. Friedman
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, Colorado 80309
| | - Mitsuyasu Hasebe
- Exploratory Research for Advanced Technology, Japan Science and Technology Agency, Okazaki 444-8585, Japan
- National Institute for Basic Biology, Okazaki 444-8585, Japan
- School of Life Science, Graduate University for Advanced Studies, Okazaki 444-8585, Japan
- Address correspondence to
| | - Minoru Kubo
- Exploratory Research for Advanced Technology, Japan Science and Technology Agency, Okazaki 444-8585, Japan
- National Institute for Basic Biology, Okazaki 444-8585, Japan
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Prigge MJ, Bezanilla M. Evolutionary crossroads in developmental biology: Physcomitrella patens. Development 2010; 137:3535-43. [DOI: 10.1242/dev.049023] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The moss Physcomitrella patens has recently emerged as a powerful genetically tractable model plant system. As a member of the bryophytes, P. patens provides a unique opportunity to study the evolution of a myriad of plant traits, such as polarized cell growth, gametophyte-to-sporophyte transitions, and sperm-to-pollen transition. The availability of a complete genome sequence, together with the ability to perform gene targeting efficiently in P. patens has spurred a flurry of elegant reverse genetic studies in this plant model that address a variety of key questions in plant developmental biology.
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Affiliation(s)
- Michael J. Prigge
- Section of Cell and Developmental Biology, University of California, San Diego, CA 92093-0116, USA
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40
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Cove DJ, Perroud PF, Charron AJ, McDaniel SF, Khandelwal A, Quatrano RS. The moss Physcomitrella patens: a novel model system for plant development and genomic studies. Cold Spring Harb Protoc 2010; 2009:pdb.emo115. [PMID: 20147063 DOI: 10.1101/pdb.emo115] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- David J Cove
- Department of Biology, Washington University, St. Louis, MO 63130, USA
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41
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Shakirov EV, Perroud PF, Nelson AD, Cannell ME, Quatrano RS, Shippen DE. Protection of Telomeres 1 is required for telomere integrity in the moss Physcomitrella patens. THE PLANT CELL 2010; 22:1838-48. [PMID: 20515974 PMCID: PMC2910979 DOI: 10.1105/tpc.110.075846] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
In vertebrates, the single-stranded telomeric DNA binding protein Protection of Telomeres 1 (POT1) shields chromosome ends and prevents them from eliciting a DNA damage response. By contrast, Arabidopsis thaliana encodes two divergent full-length POT1 paralogs that do not exhibit telomeric DNA binding in vitro and have evolved to mediate telomerase regulation instead of chromosome end protection. To further investigate the role of POT1 in plants, we established the moss Physcomitrella patens as a new model for telomere biology and a counterpoint to Arabidopsis. The sequence and architecture of the telomere tract is similar in P. patens and Arabidopsis, but P. patens harbors only a single-copy POT1 gene. Unlike At POT1 proteins, Pp POT1 efficiently bound single-stranded telomeric DNA in vitro. Deletion of the P. patens POT1 gene resulted in the rapid onset of severe developmental defects and sterility. Although telomerase activity levels were unperturbed, telomeres were substantially shortened, harbored extended G-overhangs, and engaged in end-to-end fusions. We conclude that the telomere capping function of POT1 is conserved in early diverging land plants but is subsequently lost in Arabidopsis.
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Affiliation(s)
- Eugene V. Shakirov
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128
| | | | - Andrew D. Nelson
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128
| | - Maren E. Cannell
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128
| | - Ralph S. Quatrano
- Department of Biology, Washington University, St. Louis, Missouri 63130
| | - Dorothy E. Shippen
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128
- Address correspondence to
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Wiedemann G, Hermsen C, Melzer M, Büttner-Mainik A, Rennenberg H, Reski R, Kopriva S. Targeted knock-out of a gene encoding sulfite reductase in the moss Physcomitrella patens affects gametophytic and sporophytic development. FEBS Lett 2010; 584:2271-8. [PMID: 20347810 DOI: 10.1016/j.febslet.2010.03.034] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2009] [Revised: 03/17/2010] [Accepted: 03/22/2010] [Indexed: 01/16/2023]
Abstract
A key step in sulfate assimilation into cysteine is the reduction of sulfite to sulfide by sulfite reductase (SiR). This enzyme is encoded by three genes in the moss Physcomitrella patens. To obtain a first insight into the roles of the individual isoforms, we deleted the gene encoding the SiR1 isoform in P. patens by homologous recombination and subsequently analysed the DeltaSiR1 mutants. While DeltaSiR1 mutants showed no obvious alteration in sulfur metabolism, their regeneration from protoplasts and their ability to produce mature spores was significantly affected, highlighting an unexpected link between moss sulfate assimilation and development, that is yet to be characterized.
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Affiliation(s)
- Gertrud Wiedemann
- University of Freiburg, Faculty of Biology, Plant Biotechnology, Freiburg, Germany
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Khandelwal A, Cho SH, Marella H, Sakata Y, Perroud PF, Pan A, Quatrano RS. Role of ABA and ABI3 in desiccation tolerance. Science 2010; 327:546. [PMID: 20110497 DOI: 10.1126/science.1183672] [Citation(s) in RCA: 138] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
We show in bryophytes that abscisic acid (ABA) pretreatment of moss (Physcomitrella patens) cells confers desiccation tolerance. In angiosperms, both ABA and the transcriptional regulator ABSCISIC ACID INSENSITIVE 3 (ABI3) are required to protect the seed during desiccation. ABA was not able to protect moss cells in stable deletion lines of ABI3 (DeltaPpabi3). Hence, moss has the same functional link between ABA, ABI3, and the desiccation tolerance phenotype that is found in angiosperms. Furthermore, we identified 22 genes that were induced during ABA pretreatment in wild-type lines. When their expression was compared with that of DeltaPpabi3 during ABA pretreatment and immediately after desiccation, a new target of ABI3 action appears to be in the recovery period.
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Affiliation(s)
- A Khandelwal
- Monsanto Company, 700 Chesterfield Parkway West, St. Louis, MO 63017, USA
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Kotchoni SO, Zakharova T, Mallery EL, Le J, El-Assal SED, Szymanski DB. The association of the Arabidopsis actin-related protein2/3 complex with cell membranes is linked to its assembly status but not its activation. PLANT PHYSIOLOGY 2009; 151:2095-109. [PMID: 19801398 PMCID: PMC2785977 DOI: 10.1104/pp.109.143859] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2009] [Accepted: 09/28/2009] [Indexed: 05/18/2023]
Abstract
In growing plant cells, the combined activities of the cytoskeleton, endomembrane, and cell wall biosynthetic systems organize the cytoplasm and define the architecture and growth properties of the cell. These biosynthetic machineries efficiently synthesize, deliver, and recycle the raw materials that support cell expansion. The precise roles of the actin cytoskeleton in these processes are unclear. Certainly, bundles of actin filaments position organelles and are a substrate for long-distance intracellular transport, but the functional linkages between dynamic actin filament arrays and the cell growth machinery are poorly understood. The Arabidopsis (Arabidopsis thaliana) "distorted group" mutants have defined protein complexes that appear to generate and convert small GTPase signals into an Actin-Related Protein2/3 (ARP2/3)-dependent actin filament nucleation response. However, direct biochemical knowledge about Arabidopsis ARP2/3 and its cellular distribution is lacking. In this paper, we provide biochemical evidence for a plant ARP2/3. The plant complex utilizes a conserved assembly mechanism. ARPC4 is the most critical core subunit that controls the assembly and steady-state levels of the complex. ARP2/3 in other systems is believed to be mostly a soluble complex that is locally recruited and activated. Unexpectedly, we find that Arabidopsis ARP2/3 interacts strongly with cell membranes. Membrane binding is linked to complex assembly status and not to the extent to which it is activated. Mutant analyses implicate ARP2 as an important subunit for membrane association.
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Charron AJ, Quatrano RS. Between a rock and a dry place: the water-stressed moss. MOLECULAR PLANT 2009; 2:478-86. [PMID: 19825631 DOI: 10.1093/mp/ssp018] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The earliest land plants faced a suite of abiotic stresses largely unknown to their aquatic algal ancestors. The descendants of these plants evolved two general mechanisms for survival in the relatively arid aerial environment. While the vascular plants or 'tracheophytes' developed tissue specializations to transport and retain water, the other main lineages of land plants, the bryophytes, retained a simple, nonvascular morphology. The bryophytes--mosses, hornworts, and liverworts--continually undergo a co-equilibration of their water content with the surrounding environment and rely to a great extent on intrinsic cellular mechanisms to mitigate damage due to water stress. This short review will focus on the cellular and molecular responses to dehydration and rehydration in mosses, and offer insights into general plant responses to water stress.
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Affiliation(s)
- Audra J Charron
- Department of Biology, Washington University in St Louis, 1 Brookings Dr., St Louis, MO 63130, USA
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Galletta BJ, Cooper JA. Actin and endocytosis: mechanisms and phylogeny. Curr Opin Cell Biol 2009; 21:20-7. [PMID: 19186047 DOI: 10.1016/j.ceb.2009.01.006] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2008] [Revised: 01/05/2009] [Accepted: 01/06/2009] [Indexed: 11/29/2022]
Abstract
The regulated assembly of actin filament networks is a crucial part of endocytosis, with crucial temporal and spatial relationships between proteins of the endocytic and actin assembly machinery. Of particular importance has been a wealth of studies in budding and fission yeast. Cell biology approaches, combined with molecular genetics, have begun to uncover the complexity of the regulation of actin dynamics during the endocytic process. In a wide range of organisms, clathrin-mediated endocytosis appears to be linked to Arp2/3-mediated actin assembly. The conservation of the components, across a wide range eukaryotic species, suggests that the partnership between endocytosis and actin may be evolutionarily ancient.
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Affiliation(s)
- Brian J Galletta
- Department of Cell Biology, Washington University Medical School, St Louis, MO, USA
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Sinclair A, Schenkel M, Mathur J. Signaling to the Actin Cytoskeleton During Cell Morphogenesis and Patterning. SIGNALING IN PLANTS 2009. [DOI: 10.1007/978-3-540-89228-1_7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Dyachok J, Shao MR, Vaughn K, Bowling A, Facette M, Djakovic S, Clark L, Smith L. Plasma membrane-associated SCAR complex subunits promote cortical F-actin accumulation and normal growth characteristics in Arabidopsis roots. MOLECULAR PLANT 2008; 1:990-1006. [PMID: 19825598 DOI: 10.1093/mp/ssn059] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The ARP2/3 complex, a highly conserved nucleator of F-actin polymerization, and its activator, the SCAR complex, have been shown to play important roles in leaf epidermal cell morphogenesis in Arabidopsis. However, the intracellular site(s) and function(s) of SCAR and ARP2/3 complex-dependent actin polymerization in plant cells remain unclear. We demonstrate that putative SCAR complex subunits BRK1 and SCAR1 are localized to the plasma membrane at sites of cell growth and wall deposition in expanding cells of leaves and roots. BRK1 localization is SCAR-dependent, providing further evidence of an association between these proteins in vivo. Consistent with plasma membrane localization of SCAR complex subunits, cortical F-actin accumulation in root tip cells is reduced in brk1 mutants. Moreover, mutations disrupting the SCAR or ARP2/3 complex reduce the growth rate of roots and their ability to penetrate semi-solid medium, suggesting reduced rigidity. Cell walls of mutant roots exhibit abnormal structure and composition at intercellular junctions where BRK1 and SCAR1 are enriched in the adjacent plasma membrane. Taken together, our results suggest that SCAR and ARP2/3 complex-dependent actin polymerization promotes processes at the plasma membrane that are important for normal growth and wall assembly.
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Affiliation(s)
- Julia Dyachok
- University of California San Diego, La Jolla, CA 92093-0116, USA
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Finka A, Saidi Y, Goloubinoff P, Neuhaus JM, Zrÿd JP, Schaefer DG. The knock-out of ARP3a gene affects F-actin cytoskeleton organization altering cellular tip growth, morphology and development in moss Physcomitrella patens. ACTA ACUST UNITED AC 2008; 65:769-84. [PMID: 18613119 DOI: 10.1002/cm.20298] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The seven subunit Arp2/3 complex is a highly conserved nucleation factor of actin microfilaments. We have isolated the genomic sequence encoding a putative Arp3a protein of the moss Physcomitrella patens. The disruption of this ARP3A gene by allele replacement has generated loss-of-function mutants displaying a complex developmental phenotype. The loss-of function of ARP3A gene results in shortened, almost cubic chloronemal cells displaying affected tip growth and lacking differentiation to caulonemal cells. In moss arp3a mutants, buds differentiate directly from chloronemata to form stunted leafy shoots having differentiated leaves similar to wild type. Yet, rhizoids never differentiate from stem epidermal cells. To characterize the F-actin organization in the arp3a-mutated cells, we disrupted ARP3A gene in the previously described HGT1 strain expressing conditionally the GFP-talin marker. In vivo observation of the F-actin cytoskeleton during P. patens development demonstrated that loss-of-function of Arp3a is associated with the disappearance of specific F-actin cortical structures associated with the establishment of localized cellular growth domains. Finally, we show that constitutive expression of the P. patens Arp3a and its Arabidopsis thaliana orthologs efficiently complement the mutated phenotype indicating a high degree of evolutionary conservation of the Arp3 function in land plants.
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Affiliation(s)
- Andrija Finka
- Department of Plant Molecular Biology, University of Lausanne, Lausanne, Switzerland.
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