1
|
Zhou Z, Zheng S, Haq SIU, Zheng D, Qiu QS. Regulation of pollen tube growth by cellular pH and ions. JOURNAL OF PLANT PHYSIOLOGY 2022; 277:153792. [PMID: 35973258 DOI: 10.1016/j.jplph.2022.153792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Revised: 07/29/2022] [Accepted: 08/06/2022] [Indexed: 06/15/2023]
Abstract
Tip growth of the pollen tube is a model system for the study of cell polarity establishment in flowering plants. The tip growth of the pollen tube displays an oscillating pattern corresponding to cellular ion and pH dynamics. Therefore, cellular pH and ions play an important role in pollen growth and development. In this review, we summarized the current advances in understanding the function of cellular pH and ions in regulating pollen tube growth. We analyzed the physiological roles and underlying mechanisms of cellular pH and ions, including Ca2+, K+, and Cl-, in regulating pollen tube growth. We further examined the function of Ca2+ in regulating cytoskeletons, small G proteins, and cell wall development in relation to pollen tube growth. We also examined the regulatory roles of cellular pH in pollen tube growth as well as pH regulation of ion flow, cell wall development, auxin signaling, and cytoskeleton function in pollen. In addition, we assessed the regulation of pollen tube growth by proton pumps and the maintenance of pH homeostasis in the trans-Golgi network by ion transporters. The interplay of ion homeostasis and pH dynamics was also assessed. We discussed the unanswered questions regarding pollen tube growth that need to be addressed in the future.
Collapse
Affiliation(s)
- Zhenguo Zhou
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, 73000, China.
| | - Sheng Zheng
- College of Life Sciences, Northwest Normal University, Lanzhou, Gansu, 730070, China; Academy of Plateau Science and Sustainability, Qinghai Normal University, Xining, Qinghai, 810016, China
| | - Syed Inzimam Ul Haq
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, 73000, China
| | - Dianfeng Zheng
- College of Coastal Agricultural Sciences, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China
| | - Quan-Sheng Qiu
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, 73000, China; Academy of Plateau Science and Sustainability, Qinghai Normal University, Xining, Qinghai, 810016, China; College of Coastal Agricultural Sciences, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China.
| |
Collapse
|
2
|
Scali M, Moscatelli A, Bini L, Onelli E, Vignani R, Wang W. Protein Analysis of Pollen Tubes after the Treatments of Membrane Trafficking Inhibitors Gains Insights on Molecular Mechanism Underlying Pollen Tube Polar Growth. Protein J 2021; 40:205-222. [PMID: 33751342 PMCID: PMC8019430 DOI: 10.1007/s10930-021-09972-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/19/2021] [Indexed: 12/03/2022]
Abstract
Pollen tube elongation is characterized by a highly-polarized tip growth process dependent on an efficient vesicular transport system and largely mobilized by actin cytoskeleton. Pollen tubes are an ideal model system to study exocytosis, endocytosis, membrane recycling, and signaling network coordinating cellular processes, structural organization and vesicular trafficking activities required for tip growth. Proteomic analysis was applied to identify Nicotiana tabacum Differentially Abundant Proteins (DAPs) after in vitro pollen tube treatment with membrane trafficking inhibitors Brefeldin A, Ikarugamycin and Wortmannin. Among roughly 360 proteins separated in two-dimensional gel electrophoresis, a total of 40 spots visibly changing between treated and control samples were identified by MALDI-TOF MS and LC-ESI-MS/MS analysis. The identified proteins were classified according to biological processes, and most proteins were related to pollen tube energy metabolism, including ammino acid synthesis and lipid metabolism, structural features of pollen tube growth as well modification and actin cytoskeleton organization, stress response, and protein degradation. In-depth analysis of proteins corresponding to energy-related pathways revealed the male gametophyte to be a reliable model of energy reservoir and dynamics.
Collapse
Affiliation(s)
- Monica Scali
- Department of Life Sciences, University of Siena, Siena, Italy.
| | | | - Luca Bini
- Department of Life Sciences, University of Siena, Siena, Italy
| | | | - Rita Vignani
- Department of Life Sciences, University of Siena, Siena, Italy
| | - Wei Wang
- College of Life Sciences, Henan Agricultural University, Zhengzhou, China
| |
Collapse
|
3
|
Foissner I, Hoeftberger M, Hoepflinger MC, Sommer A, Bulychev AA. Brefeldin A inhibits clathrin-dependent endocytosis and ion transport in Chara internodal cells. Biol Cell 2020; 112:317-334. [PMID: 32648585 DOI: 10.1111/boc.202000031] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 05/27/2020] [Accepted: 05/28/2020] [Indexed: 11/30/2022]
Abstract
BACKGROUND The Characeae are multicellular green algae, which are closely related to higher plants. Their internodal cells are a convenient model to study membrane transport and organelle interactions. RESULTS In this study, we report on the effect of brefeldin A (BFA), an inhibitor of vesicle trafficking, on internodal cells of Chara australis. BFA induced the commonly observed agglomeration of Golgi bodies and trans Golgi network into 'brefeldin compartments' at concentrations between 6 and 500 μM and within 30-120 min treatment. In contrast to most other cells, however, BFA inhibited endocytosis and significantly decreased the number of clathrin-coated pits and clathrin-coated vesicles at the plasma membrane. BFA did not inhibit secretion of organelles at wounds induced by puncturing or local light damage but prevented the formation of cellulosic wound walls probably because of insufficient membrane recycling. We also found that BFA inhibited the formation of alkaline and acid regions along the cell surface ('pH banding pattern') which facilitates carbon uptake required for photosynthesis; we hypothesise that this is due to insufficient recycling of ion transporters. During long-term treatments over several days, BFA delayed the formation of complex 3D plasma membranes (charasomes). Interestingly, BFA had no detectable effect on clathrin-dependent charasome degradation. Protein sequence analysis suggests that the peculiar effects of BFA in Chara internodal cells are due to a mutation in the guanine-nucleotide exchange factor GNOM required for recruitment of membrane coats via activation of ADP-ribosylation factor proteins. CONCLUSIONS AND SIGNIFICANCE This work provides an overview on the effects of BFA on different processes in C. australis. It revealed similarities but also distinct differences in vesicle trafficking between higher plant and algal cells. It shows that characean internodal cells are a promising model to study interactions between seemingly distant metabolic pathways.
Collapse
Affiliation(s)
- Ilse Foissner
- Department of Biosciences, University of Salzburg, Salzburg, Austria
| | | | | | - Aniela Sommer
- Department of Biosciences, University of Salzburg, Salzburg, Austria
| | - Alexander A Bulychev
- Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
| |
Collapse
|
4
|
Oulehlová D, Kollárová E, Cifrová P, Pejchar P, Žárský V, Cvrčková F. Arabidopsis Class I Formin FH1 Relocates between Membrane Compartments during Root Cell Ontogeny and Associates with Plasmodesmata. PLANT & CELL PHYSIOLOGY 2019; 60:1855-1870. [PMID: 31135031 DOI: 10.1093/pcp/pcz102] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 05/14/2019] [Indexed: 05/03/2023]
Abstract
Formins are evolutionarily conserved eukaryotic proteins engaged in actin nucleation and other aspects of cytoskeletal organization. Angiosperms have two formin clades with multiple paralogs; typical plant Class I formins are integral membrane proteins that can anchor cytoskeletal structures to membranes. For the main Arabidopsis housekeeping Class I formin, FH1 (At3g25500), plasmalemma localization was documented in heterologous expression and overexpression studies. We previously showed that loss of FH1 function increases cotyledon epidermal pavement cell shape complexity via modification of actin and microtubule organization and dynamics. Here, we employ transgenic Arabidopsis expressing green fluorescent protein-tagged FH1 (FH1-GFP) from its native promoter to investigate in vivo behavior of this formin using advanced microscopy techniques. The fusion protein is functional, since its expression complements the fh1 loss-of-function mutant phenotype. Accidental overexpression of FH1-GFP results in a decrease in trichome branch number, while fh1 mutation has the opposite effect, indicating a general role of this formin in controlling cell shape complexity. Consistent with previous reports, FH1-GFP associates with membranes. However, the protein exhibits surprising actin- and secretory pathway-dependent dynamic localization and relocates between cellular endomembranes and the plasmalemma during cell division and differentiation in root tissues, with transient tonoplast localization at the transition/elongation zones border. FH1-GFP also accumulates in actin-rich regions of cortical cytoplasm and associates with plasmodesmata in both the cotyledon epidermis and root tissues. Together with previous reports from metazoan systems, this suggests that formins might have a shared (ancestral or convergent) role at cell-cell junctions.
Collapse
Affiliation(s)
- Denisa Oulehlová
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague 2, CZ 128 43, Czech Republic
- Institute of Experimental Botany of the CAS, Prague 6, CZ 165 02, Czech Republic
| | - Eva Kollárová
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague 2, CZ 128 43, Czech Republic
| | - Petra Cifrová
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague 2, CZ 128 43, Czech Republic
| | - Přemysl Pejchar
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague 2, CZ 128 43, Czech Republic
- Institute of Experimental Botany of the CAS, Prague 6, CZ 165 02, Czech Republic
| | - Viktor Žárský
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague 2, CZ 128 43, Czech Republic
- Institute of Experimental Botany of the CAS, Prague 6, CZ 165 02, Czech Republic
| | - Fatima Cvrčková
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague 2, CZ 128 43, Czech Republic
| |
Collapse
|
5
|
Zhang S, Wang C, Xie M, Liu J, Kong Z, Su H. Actin Bundles in The Pollen Tube. Int J Mol Sci 2018; 19:ijms19123710. [PMID: 30469514 PMCID: PMC6321563 DOI: 10.3390/ijms19123710] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Revised: 11/18/2018] [Accepted: 11/19/2018] [Indexed: 12/31/2022] Open
Abstract
The angiosperm pollen tube delivers two sperm cells into the embryo sac through a unique growth strategy, named tip growth, to accomplish fertilization. A great deal of experiments have demonstrated that actin bundles play a pivotal role in pollen tube tip growth. There are two distinct actin bundle populations in pollen tubes: the long, rather thick actin bundles in the shank and the short, highly dynamic bundles near the apex. With the development of imaging techniques over the last decade, great breakthroughs have been made in understanding the function of actin bundles in pollen tubes, especially short subapical actin bundles. Here, we tried to draw an overall picture of the architecture, functions and underlying regulation mechanism of actin bundles in plant pollen tubes.
Collapse
Affiliation(s)
- Shujuan Zhang
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education College of Life Science, Northwest University, Xi'an 710069, China.
| | - Chunbo Wang
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education College of Life Science, Northwest University, Xi'an 710069, China.
| | - Min Xie
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education College of Life Science, Northwest University, Xi'an 710069, China.
| | - Jinyu Liu
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education College of Life Science, Northwest University, Xi'an 710069, China.
| | - Zhe Kong
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education College of Life Science, Northwest University, Xi'an 710069, China.
| | - Hui Su
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education College of Life Science, Northwest University, Xi'an 710069, China.
| |
Collapse
|
6
|
Qu X, Zhang R, Zhang M, Diao M, Xue Y, Huang S. Organizational Innovation of Apical Actin Filaments Drives Rapid Pollen Tube Growth and Turning. MOLECULAR PLANT 2017; 10:930-947. [PMID: 28502709 DOI: 10.1016/j.molp.2017.05.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 04/15/2017] [Accepted: 05/01/2017] [Indexed: 06/07/2023]
Abstract
Polarized tip growth is a fundamental cellular process in many eukaryotes. In this study, we examined the dynamic restructuring of the actin cytoskeleton and its relationship to vesicle transport during pollen tip growth in Arabidopsis. We found that actin filaments originating from the apical membrane form a specialized structure consisting of longitudinally aligned actin bundles at the cortex and inner cytoplasmic filaments with a distinct distribution. Using actin-based pharmacological treatments and genetic mutants in combination with FRAP (fluorescence recovery after photobleaching) technology to visualize the transport of vesicles within the growth domain of pollen tubes, we demonstrated that cortical actin filaments facilitate tip-ward vesicle transport. We also discovered that the inner apical actin filaments prevent backward movement of vesicles, thus ensuring that sufficient vesicles accumulate at the pollen tube tip to support the rapid growth of the pollen tube. The combinatorial effect of cortical and internal apical actin filaments perfectly explains the generation of the inverted "V" cone-shaped vesicle distribution pattern at the pollen tube tip. When pollen tubes turn, apical actin filaments at the facing side undergo depolymerization and repolymerization to reorient the apical actin structure toward the new growth direction. This actin restructuring precedes vesicle accumulation and changes in tube morphology. Thus, our study provides new insights into the functional relationship between actin dynamics and vesicle transport during rapid and directional pollen tube growth.
Collapse
Affiliation(s)
- Xiaolu Qu
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Ruihui Zhang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Meng Zhang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China; Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Min Diao
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China; Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Yongbiao Xue
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
| | - Shanjin Huang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China; Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
| |
Collapse
|
7
|
Abstract
The eukaryotic actin cytoskeleton is a highly dynamic framework that is involved in many biological processes, such as cell growth, division, morphology, and motility. G-actin polymerizes into microfilaments that associate into bundles, patches, and networks, which, in turn, organize into higher order structures that are fundamental for the course of important physiological events. Actin rings are an example for such higher order actin entities, but this term represents an actually diverse set of subcellular structures that are involved in various processes. This review especially sheds light on a crucial type of non-constricting ring-like actin networks, and categorizes them under the term 'actin fringe'. These 'actin fringes' are visualized as highly dynamic and yet steady structures in the tip of various polarized growing cells. The present comprehensive overview compares the actin fringe characteristics of rapidly elongating pollen tubes with several related actin arrays in other cell types of diverse species. The current state of knowledge about various actin fringe functions is summarized, and the key role of this structure in the polar growth process is discussed.
Collapse
Affiliation(s)
- Octavian O H Stephan
- Department of Biology, Friedrich-Alexander University of Erlangen-Nuremberg, Erlangen, Bavaria 91058, Germany
| |
Collapse
|
8
|
Li S, Dong H, Pei W, Liu C, Zhang S, Sun T, Xue X, Ren H. LlFH1-mediated interaction between actin fringe and exocytic vesicles is involved in pollen tube tip growth. THE NEW PHYTOLOGIST 2017; 214:745-761. [PMID: 28092406 DOI: 10.1111/nph.14395] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 11/16/2016] [Indexed: 05/15/2023]
Abstract
Pollen tube tip growth is an extreme form of polarized cell growth, which requires polarized exocytosis based on a dynamic actin cytoskeleton. However, the molecular basis for the connection between actin filaments and exocytic vesicles is unclear. Here, we identified a Lilium longiflorum pollen-specific formin (LlFH1) and found that it localized at the apical vesicles and plasma membrane (PM). Overexpression of LlFH1 induced excessive actin cables in the tube tip region, and downregulation of LlFH1 eliminated the actin fringe. Fluorescence recovery after photobleaching (FRAP) analysis revealed that LlFH1-labeled exocytic vesicles exhibited an initial accumulation at the shoulder of the apex and coincided with the leading edge of the actin fringe. Time-lapse analysis suggested that nascent actin filaments followed the emergence of the apical vesicles, implying that LlFH1 at apical vesicles could initiate actin polymerization. Biochemical assays showed that LlFH1 FH1FH2 could nucleate actin polymerization, but then capped the actin filament at the barbed end and inhibited its elongation. However, in the presence of lily profilins, LlFH1 FH1FH2 could accelerate barbed-end actin elongation. In addition, LlFH1 FH1FH2 was able to bundle actin filaments. Thus, we propose that LlFH1 and profilin coordinate the interaction between the actin fringe and exocytic vesicle trafficking during pollen tube growth of lily.
Collapse
Affiliation(s)
- Shanwei Li
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education and College of Life Science, Beijing Normal University, Beijing, 100875, China
| | - Huaijian Dong
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education and College of Life Science, Beijing Normal University, Beijing, 100875, China
| | - 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
| | - Chaonan Liu
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education and College of Life Science, Beijing Normal University, Beijing, 100875, China
| | - Sha Zhang
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education and College of Life Science, Beijing Normal University, Beijing, 100875, China
| | - Tiantian Sun
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education and College of Life Science, Beijing Normal University, Beijing, 100875, China
| | - Xiuhua Xue
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education and College of Life Science, Beijing Normal University, Beijing, 100875, China
| | - Haiyun Ren
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education and College of Life Science, Beijing Normal University, Beijing, 100875, China
| |
Collapse
|
9
|
Roldán JA, Rojas HJ, Goldraij A. In vitro inhibition of incompatible pollen tubes in Nicotiana alata involves the uncoupling of the F-actin cytoskeleton and the endomembrane trafficking system. PROTOPLASMA 2015; 252:63-75. [PMID: 24841893 DOI: 10.1007/s00709-014-0658-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Accepted: 05/07/2014] [Indexed: 06/03/2023]
Abstract
In the S-RNase-based self-incompatibility system, subcellular events occurring in the apical region of incompatible pollen tubes during the pollen rejection process are poorly understood. F-actin dynamics and endomembrane trafficking are crucial for polar growth, which is temporally and spatially controlled in the tip region of pollen tubes. Thus, we developed a simple in vitro assay to study the changes in the F-actin cytoskeleton and the endomembrane system at the apical region of incompatible pollen tubes in Nicotiana alata. Growth but not germination of pollen tubes of S c₁₀-, S₇₀-, and S₇₅-haplotypes was selectively inhibited by style extracts carrying the same haplotypes. Pollen F-actin cytoskeleton and endomembrane system, visualized by fluorescent markers, were normal during the initial 60 min of pollen culture in the presence of compatible and incompatible style extracts. Additional culture resulted in complete growth arrest and critical alterations in the integrity of the F-actin cytoskeleton and the endomembrane system of incompatible pollen tubes. The F-actin ring and the V-shaped zone disappeared from the apical region, while distorted F-actin cables and progressive formation of membrane aggregates evolved in the subapical region and the shank. The vacuolar network of incompatible pollen tubes invaded the tip region, but vacuolar membrane integrity remained mostly unaffected. The polar growth machinery of incompatible pollen tubes was uncoupled, as evidenced by the severe disruption of colocalization between the F-actin cytoskeleton and the endomembrane compartments. A model of pollen rejection integrating the main subcellular events occurring in incompatible pollen is discussed.
Collapse
Affiliation(s)
- Juan A Roldán
- Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC-CONICET), Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, X5000HUA, Córdoba, Argentina
| | | | | |
Collapse
|
10
|
Worden N, Esteve VE, Domozych DS, Drakakaki G. Using chemical genomics to study cell wall formation and cell growth in Arabidopsis thaliana and Penium margaritaceum. Methods Mol Biol 2015; 1242:23-39. [PMID: 25408440 DOI: 10.1007/978-1-4939-1902-4_2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The cell wall is directly involved in cell growth, and its ability to loosen and rearrange allows for cell expansion through the existing turgor pressure. Thus, information on cell wall deposition and rearrangement can provide insights into the overall plant growth. This chapter describes two methods that can be used to evaluate cell expansion (1) in the model plant Arabidopsis thaliana and (2) the model alga Penium margaritaceum. These methods are further used to screen for small molecules that induce cell growth phenotypic changes affecting cell wall. Identification of such small molecules is beneficial due to their posttranslational mechanism of action that can be controlled in a temporal and spatial manner. Chemical genomics has the ability to overcome issues of genetic redundancy and lethality, which can hinder traditional genetic methods. The identification of small molecules in these screens will provide useful information on plant cell wall biology and overall plant growth.
Collapse
Affiliation(s)
- N Worden
- Department of Plant Sciences, University of California Davis, One Shields Avenue, Davis, CA, 95616, USA
| | | | | | | |
Collapse
|
11
|
Rounds CM, Hepler PK, Winship LJ. The apical actin fringe contributes to localized cell wall deposition and polarized growth in the lily pollen tube. PLANT PHYSIOLOGY 2014; 166:139-51. [PMID: 25037212 PMCID: PMC4149702 DOI: 10.1104/pp.114.242974] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Accepted: 07/08/2014] [Indexed: 05/19/2023]
Abstract
In lily (Lilium formosanum) pollen tubes, pectin, a major component of the cell wall, is delivered through regulated exocytosis. The targeted transport and secretion of the pectin-containing vesicles may be controlled by the cortical actin fringe at the pollen tube apex. Here, we address the role of the actin fringe using three different inhibitors of growth: brefeldin A, latrunculin B, and potassium cyanide. Brefeldin A blocks membrane trafficking and inhibits exocytosis in pollen tubes; it also leads to the degradation of the actin fringe and the formation of an aggregate of filamentous actin at the base of the clear zone. Latrunculin B, which depolymerizes filamentous actin, markedly slows growth but allows focused pectin deposition to continue. Of note, the locus of deposition shifts frequently and correlates with changes in the direction of growth. Finally, potassium cyanide, an electron transport chain inhibitor, briefly stops growth while causing the actin fringe to completely disappear. Pectin deposition continues but lacks focus, instead being delivered in a wide arc across the pollen tube tip. These data support a model in which the actin fringe contributes to the focused secretion of pectin to the apical cell wall and, thus, to the polarized growth of the pollen tube.
Collapse
Affiliation(s)
- Caleb M Rounds
- Department of Biology, University of Massachusetts, Amherst, Massachusetts 01003 (C.M.R., P.K.H.); andSchool of Natural Science, Hampshire College, Amherst, Massachusetts 01002 (L.J.W.)
| | - Peter K Hepler
- Department of Biology, University of Massachusetts, Amherst, Massachusetts 01003 (C.M.R., P.K.H.); andSchool of Natural Science, Hampshire College, Amherst, Massachusetts 01002 (L.J.W.)
| | - Lawrence J Winship
- Department of Biology, University of Massachusetts, Amherst, Massachusetts 01003 (C.M.R., P.K.H.); andSchool of Natural Science, Hampshire College, Amherst, Massachusetts 01002 (L.J.W.)
| |
Collapse
|
12
|
Takahashi K, Hayashi KI, Kinoshita T. Auxin activates the plasma membrane H+-ATPase by phosphorylation during hypocotyl elongation in Arabidopsis. PLANT PHYSIOLOGY 2012; 159:632-41. [PMID: 22492846 PMCID: PMC3375930 DOI: 10.1104/pp.112.196428] [Citation(s) in RCA: 224] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
The phytohormone auxin is a major regulator of diverse aspects of plant growth and development. The ubiquitin-ligase complex SCF(TIR1/AFB) (for Skp1-Cul1-F-box protein), which includes the TRANSPORT INHIBITOR RESPONSE1/AUXIN SIGNALING F-BOX (TIR1/AFB) auxin receptor family, has recently been demonstrated to be critical for auxin-mediated transcriptional regulation. Early-phase auxin-induced hypocotyl elongation, on the other hand, has long been explained by the acid-growth theory, for which proton extrusion by the plasma membrane H(+)-ATPase is a functional prerequisite. However, the mechanism by which auxin mediates H(+)-ATPase activation has yet to be elucidated. Here, we present direct evidence for H(+)-ATPase activation in etiolated hypocotyls of Arabidopsis (Arabidopsis thaliana) by auxin through phosphorylation of the penultimate threonine during early-phase hypocotyl elongation. Application of the natural auxin indole-3-acetic acid (IAA) to endogenous auxin-depleted hypocotyl sections induced phosphorylation of the penultimate threonine of the H(+)-ATPase and increased H(+)-ATPase activity without altering the amount of the enzyme. Changes in both the phosphorylation level of H(+)-ATPase and IAA-induced elongation were similarly concentration dependent. Furthermore, IAA-induced H(+)-ATPase phosphorylation occurred in a tir1-1 afb2-3 double mutant, which is severely defective in auxin-mediated transcriptional regulation. In addition, α-(phenylethyl-2-one)-IAA, the auxin antagonist specific for the nuclear auxin receptor TIR1/AFBs, had no effect on IAA-induced H(+)-ATPase phosphorylation. These results suggest that the TIR1/AFB auxin receptor family is not involved in auxin-induced H(+)-ATPase phosphorylation. Our results define the activation mechanism of H(+)-ATPase by auxin during early-phase hypocotyl elongation; this is the long-sought-after mechanism that is central to the acid-growth theory.
Collapse
|
13
|
Guo F, McCubbin AG. The pollen-specific R-SNARE/longin PiVAMP726 mediates fusion of endo- and exocytic compartments in pollen tube tip growth. JOURNAL OF EXPERIMENTAL BOTANY 2012; 63:3083-95. [PMID: 22345643 PMCID: PMC3350921 DOI: 10.1093/jxb/ers023] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Revised: 01/13/2012] [Accepted: 01/17/2012] [Indexed: 05/06/2023]
Abstract
The growing pollen tube apex is dedicated to balancing exo- and endocytic processes to form a rapidly extending tube. As perturbation of either tends to cause a morphological phenotype, this system provides tractable model for studying these processes. Vesicle-associated membrane protein 7s (VAMP7s) are members of the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) family that mediate cognate membrane fusion but their role in pollen tube growth has not been investigated. This manuscript identifies PiVAMP726 of Petunia inflata as a pollen-specific VAMP7 that localizes to the inverted cone of transport vesicles at the pollen tube tip. The endocytic marker FM4-64 was found to colocalize with yellow fluorescent protein (YFP)-PiVAMP726, which is consistent with PiVAMP726 containing an amino-acid motif implicated in endosomal localization, At high overexpression levels, YFP- PiVAMP726 inhibited growth and caused the formation of novel membrane compartments within the pollen tube tip. Functional dissection of PiVAMP726 implicated the N-terminal longin domain in negative regulation of the SNARE activity, but not localization of PiVAMP726. Expression of the constitutively active C-terminal SNARE domain alone, in pollen tubes, generated similar phenotypes to the full-length protein, but the truncated domain was more potent than the wild-type protein at both inhibiting growth and forming the novel membrane compartments. Both endo- and exocytic markers localized to these compartments in addition to YFP-PiVAMP726, leading to the speculation that PiVAMP726 might be involved in the recycling of endocytic vesicles in tip growth.
Collapse
Affiliation(s)
| | - Andrew G. McCubbin
- School of Biological Sciences, Washington State University, Pullman, WA 99164-4236, USA
| |
Collapse
|
14
|
|
15
|
Takác T, Pechan T, Richter H, Müller J, Eck C, Böhm N, Obert B, Ren H, Niehaus K, Samaj J. Proteomics on brefeldin A-treated Arabidopsis roots reveals profilin 2 as a new protein involved in the cross-talk between vesicular trafficking and the actin cytoskeleton. J Proteome Res 2010; 10:488-501. [PMID: 21090759 DOI: 10.1021/pr100690f] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The growing importance of vesicular trafficking and cytoskeleton dynamic reorganization during plant development requires the exploitation of novel experimental approaches. Several genetic and cell biological studies have used diverse pharmaceutical drugs that inhibit vesicular trafficking and secretion to study these phenomena. Here, proteomic and cell biology approaches were applied to study effects of brefeldin A (BFA), an inhibitor of vesicle recycling and secretion, in Arabidopsis roots. The main aim of this study was to obtain an overview of proteins affected by BFA, but especially to identify new proteins involved in the vesicular trafficking and its cross-talk to the actin cytoskeleton. The results showed that BFA altered vesicular trafficking and caused the formation of BFA-compartments which was accompanied by differential expression of several proteins in root cells. Some of the BFA-up-regulated proteins belong to the class of the vesicular trafficking proteins, such as V-ATPase and reversibly glycosylated polypeptide, while others, such as profilin 2 and elongation factor 1 alpha, are rather involved in the remodeling of the actin cytoskeleton. Upregulation of profilin 2 by BFA was verified by immunoblot and live imaging at subcellular level. The latter approach also revealed that profilin 2 accumulated in BFA-compartments which was accompanied by remodeling of the actin cytoskeleton in BFA-treated root cells. Thus, profilin 2 seems to be involved in the cross-talk between vesicular trafficking and the actin cytoskeleton, in a BFA-dependent manner.
Collapse
Affiliation(s)
- Tomás Takác
- Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Department of Cell Biology, Palacký University, Olomouc, Czech Republic.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Zhang Y, He J, Lee D, McCormick S. Interdependence of endomembrane trafficking and actin dynamics during polarized growth of Arabidopsis pollen tubes. PLANT PHYSIOLOGY 2010; 152:2200-10. [PMID: 20181757 PMCID: PMC2850033 DOI: 10.1104/pp.109.142349] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
During polarized growth of pollen tubes, endomembrane trafficking and actin polymerization are two critical processes that establish membrane/wall homeostasis and maintain growth polarity. Fine-tuned interactions between these two processes are therefore necessary but poorly understood. To better understand such cross talk in the model plant Arabidopsis (Arabidopsis thaliana), we first established optimized concentrations of drugs that interfere with either endomembrane trafficking or the actin cytoskeleton, then examined pollen tube growth using fluorescent protein markers that label transport vesicles, endosomes, or the actin cytoskeleton. Both brefeldin A (BFA) and wortmannin disturbed the motility and structural integrity of ARA7- but not ARA6-labeled endosomes, suggesting heterogeneity of the endosomal populations. Disrupting endomembrane trafficking by BFA or wortmannin perturbed actin polymerization at the apical region but not in the longitudinal actin cables in the shank. The interference of BFA/wortmannin with actin polymerization was progressive rather than rapid, suggesting an indirect effect, possibly due to perturbed endomembrane trafficking of certain membrane-localized signaling proteins. Both the actin depolymerization drug latrunculin B and the actin stabilization drug jasplakinolide rapidly disrupted transport of secretory vesicles, but each drug caused distinct responses on different endosomal populations labeled by ARA6 or ARA7, indicating that a dynamic actin cytoskeleton was critical for some steps in endomembrane trafficking. Our results provide evidence of cross talk between endomembrane trafficking and the actin cytoskeleton in pollen tubes.
Collapse
|
17
|
Klima A, Foissner I. FM dyes label sterol-rich plasma membrane domains and are internalized independently of the cytoskeleton in characean internodal cells. PLANT & CELL PHYSIOLOGY 2008; 49:1508-21. [PMID: 18757863 DOI: 10.1093/pcp/pcn122] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
We applied the endocytic markers FM1-43, FM4-64 and filipin to internodal cells of the green alga Chara corallina. Both FM dyes stained stable, long-living plasma membrane patches with a diameter of up to 1 microm. After 5 min, FM dyes labeled cortical, trembling structures up to 500 nm in size. After 15 min, FM dyes localized to endoplasmic organelles up to 1 microm in diameter, which migrated actively along actin bundles or participated in cytoplasmic mass streaming. After 30-60 min, FM fluorescence appeared in the membrane of small, endoplasmic vacuoles but not in that of the central vacuole. Some of the FM-labeled organelles were also stained by neutral red and lysotracker yellow, indicative of acidic compartments. Filipin, a sterol-specific marker, likewise labeled plasma membrane domains which co-localized with the FM patches. However, internalization of filipin could not be observed. KCN, cytochalasin D, latrunculin B and oryzalin had no effect on size, shape and distribution of FM- and filipin-labeled plasma membrane domains. Internalization of FM dyes was inhibited by KCN but not by drugs which interfere with the actin or microtubule cytoskeleton. Our data indicate that the plasma membrane of characean internodal cells contains discrete domains which are enriched in sterols and probably correspond to clusters of lipid rafts. The inhibitor experiments suggest that FM uptake is active but independent of actin filaments, actin polymerization and microtubules. The possible function of the sterol-rich, FM labeled plasma membrane areas and the significance of actin-independent FM internalization (via endocytosis or energy-dependent flippases) are discussed.
Collapse
Affiliation(s)
- Andreas Klima
- Department of Cell Biology, Division of Plant Physiology, University of Salzburg, Hellbrunnerstrasse 34, A-5020 Salzburg, Austria
| | | |
Collapse
|
18
|
Wang HJ, Wan AR, Jauh GY. An actin-binding protein, LlLIM1, mediates calcium and hydrogen regulation of actin dynamics in pollen tubes. PLANT PHYSIOLOGY 2008; 147:1619-36. [PMID: 18480376 PMCID: PMC2492651 DOI: 10.1104/pp.108.118604] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Actin microfilaments are crucial for polar cell tip growth, and their configurations and dynamics are regulated by the actions of various actin-binding proteins (ABPs). We explored the function of a lily (Lilium longiflorum) pollen-enriched LIM domain-containing protein, LlLIM1, in regulating the actin dynamics in elongating pollen tube. Cytological and biochemical assays verified LlLIM1 functioning as an ABP, promoting filamentous actin (F-actin) bundle assembly and protecting F-actin against latrunculin B-mediated depolymerization. Overexpressed LlLIM1 significantly disturbed pollen tube growth and morphology, with multiple tubes protruding from one pollen grain and coaggregation of FM4-64-labeled vesicles and Golgi apparatuses at the subapex of the tube tip. Moderate expression of LlLIM1 induced an oscillatory formation of asterisk-shaped F-actin aggregates that oscillated with growth period but in different phases at the subapical region. These results suggest that the formation of LlLIM1-mediated overstabilized F-actin bundles interfered with endomembrane trafficking to result in growth retardation. Cosedimentation assays revealed that the binding affinity of LlLIM1 to F-actin was simultaneously regulated by both pH and Ca(2+): LlLIM1 showed a preference for F-actin binding under low pH and low Ca(2+) concentration. The potential functions of LlLIM1 as an ABP sensitive to pH and calcium in integrating endomembrane trafficking, oscillatory pH, and calcium circumstances to regulate tip-focused pollen tube growth are discussed.
Collapse
Affiliation(s)
- Huei-Jing Wang
- Institute of Plant and Microbial Biology, Academia Sinica, Nankang, Taipei 115, Taiwan, Republic of China
| | | | | |
Collapse
|
19
|
Cheung AY, Duan QH, Costa SS, de Graaf BHJ, Di Stilio VS, Feijo J, Wu HM. The dynamic pollen tube cytoskeleton: live cell studies using actin-binding and microtubule-binding reporter proteins. MOLECULAR PLANT 2008; 1:686-702. [PMID: 19825573 DOI: 10.1093/mp/ssn026] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Pollen tubes elongate within the pistil to transport sperm cells to the embryo sac for fertilization. Growth occurs exclusively at the tube apex, rendering pollen tube elongation a most dramatic polar cell growth process. A hallmark pollen tube feature is its cytoskeleton, which comprises elaborately organized and dynamic actin microfilaments and microtubules. Pollen tube growth is dependent on the actin cytoskeleton; its organization and regulation have been examined extensively by various approaches, including fluorescent protein labeled actin-binding proteins in live cell studies. Using the previously described GFP-NtADF1 and GFP-LlADF1, and a new actin reporter protein NtPLIM2b-GFP, we re-affirm that the predominant actin structures in elongating tobacco and lily pollen tubes are long, streaming actin cables along the pollen tube shank, and a subapical structure comprising shorter actin cables. The subapical collection of actin microfilaments undergoes dynamic changes, giving rise to the appearance of structures that range from basket- or funnel-shaped, mesh-like to a subtle ring. NtPLIM2b-GFP is used in combination with a guanine nucleotide exchange factor for the Rho GTPases, AtROP-GEF1, to illustrate the use of these actin reporter proteins to explore the linkage between the polar cell growth process and its actin cytoskeleton. Contrary to the actin cytoskeleton, microtubules appear not to play a direct role in supporting the polar cell growth process in angiosperm pollen tubes. Using a microtubule reporter protein based on the microtubule end-binding protein from Arabidopsis AtEB1, GFP-AtEB1, we show that the extensive microtubule network in elongating pollen tubes displays varying degrees of dynamics. These reporter proteins provide versatile tools to explore the functional connection between major structural and signaling components of the polar pollen tube growth process.
Collapse
Affiliation(s)
- Alice Y Cheung
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA 01003, USA.
| | | | | | | | | | | | | |
Collapse
|
20
|
Foissner I, Wasteneys GO. Wide-ranging effects of eight cytochalasins and latrunculin A and B on intracellular motility and actin filament reorganization in characean internodal cells. PLANT & CELL PHYSIOLOGY 2007; 48:585-97. [PMID: 17327257 DOI: 10.1093/pcp/pcm030] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Numerous forms of cytochalasins have been identified and, although they share common biological activity, they may differ considerably in potency. We investigated the effects of cytochalasins A, B, C, D, E, H and J and dihydrocytochalasin B in an ideal experimental system for cell motility, the giant internodal cells of the characean alga Nitella pseudoflabellata. Cytochalasins D (60 microM) and H (30 microM) were found to be most suited for fast and reversible inhibition of actin-based motility, while cytochalasins A and E arrested streaming at lower concentrations but irreversibly. We observed no clear correlation between the ability of cytochalasins to inhibit motility and the actual disruption of the subcortical actin bundle tracks on which myosin-dependent motility occurs. Indeed, the actin bundles remained intact at the time of streaming cessation and disassembled only after one to several days' treatment. Even when applied at concentrations lower than that required to inhibit cytoplasmic streaming, all of the cytochalasins induced reorganization of the more labile cortical actin filaments into actin patches, swirling clusters or short rods. Latrunculins A and B arrested streaming only after disrupting the subcortical actin bundles, a process requiring relatively high concentrations (200 microM) and very long treatment periods of >1 d. Latrunculins, however, worked synergistically with cytochalasins. A 1 h treatment with 15 nM latrunculin A and 4 microM cytochalasin D induced reversible fragmentation of subcortical actin bundles and arrested cytoplasmic streaming. Our findings provide insights into the mechanisms by which cytochalasins and latrunculins interfere with characean actin to inhibit motility.
Collapse
Affiliation(s)
- Ilse Foissner
- Department of Cell Biology, University of Salzburg, Salzburg, Austria.
| | | |
Collapse
|
21
|
Fabian L, Troscianczuk J, Forer A. Calyculin A, an enhancer of myosin, speeds up anaphase chromosome movement. CELL & CHROMOSOME 2007; 6:1. [PMID: 17381845 PMCID: PMC1847834 DOI: 10.1186/1475-9268-6-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/19/2007] [Accepted: 03/24/2007] [Indexed: 12/23/2022]
Abstract
Actin and myosin inhibitors often blocked anaphase movements in insect spermatocytes in previous experiments. Here we treat cells with an enhancer of myosin, Calyculin A, which inhibits myosin-light-chain phosphatase from dephosphorylating myosin; myosin thus is hyperactivated. Calyculin A causes anaphase crane-fly spermatocyte chromosomes to accelerate poleward; after they reach the poles they often move back toward the equator. When added during metaphase, chromosomes at anaphase move faster than normal. Calyculin A causes prometaphase chromosomes to move rapidly up and back along the spindle axis, and to rotate. Immunofluorescence staining with an antibody against phosphorylated myosin regulatory light chain (p-squash) indicated increased phosphorylation of cleavage furrow myosin compared to control cells, indicating that calyculin A indeed increased myosin phosphorylation. To test whether the Calyculin A effects are due to myosin phosphatase or to type 2 phosphatases, we treated cells with okadaic acid, which inhibits protein phosphatase 2A at concentrations similar to Calyculin A but requires much higher concentrations to inhibit myosin phosphatase. Okadaic acid had no effect on chromosome movement. Backward movements did not require myosin or actin since they were not affected by 2,3-butanedione monoxime or LatruculinB. Calyculin A affects the distribution and organization of spindle microtubules, spindle actin, cortical actin and putative spindle matrix proteins skeletor and titin, as visualized using immunofluorescence. We discuss how accelerated and backwards movements might arise.
Collapse
Affiliation(s)
- Lacramioara Fabian
- Department of Biology, York University, Toronto, Ontario, M3J 1P3, Canada
| | | | - Arthur Forer
- Department of Biology, York University, Toronto, Ontario, M3J 1P3, Canada
| |
Collapse
|
22
|
Samaj J, Müller J, Beck M, Böhm N, Menzel D. Vesicular trafficking, cytoskeleton and signalling in root hairs and pollen tubes. TRENDS IN PLANT SCIENCE 2006; 11:594-600. [PMID: 17092761 DOI: 10.1016/j.tplants.2006.10.002] [Citation(s) in RCA: 150] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2006] [Revised: 09/11/2006] [Accepted: 10/23/2006] [Indexed: 05/12/2023]
Abstract
Root hairs and pollen tubes show strictly polar cell expansion called tip growth. Recent studies of tip growth in root hairs and pollen tubes have revealed that small GTPases of the Rab, Arf and Rho/Rac families, along with their regulatory proteins, are essential for spatio-temporal regulation of vesicular trafficking, cytoskeleton organization and signalling. ROP/RAC GTPases are involved in a multiplicity of functions including the regulation of cytoskeleton organization, calcium signalling and endocytosis in pollen tubes and root hairs. One of the most exciting recent discoveries is the preferential localization of vesicles of the trans-Golgi network (TGN), defined by specific RAB GTPases, in the apical "clear zone" and the definition of TGN as a bona fide organelle involved in both polarized secretion and endocytosis. The TGN is thought to serve the function of an early endosome in plants because it is involved in early endocytosis and rapid vesicular recycling of the plasma membrane in root epidermal cells.
Collapse
Affiliation(s)
- Jozef Samaj
- Institute of Cellular and Molecular Botany, University of Bonn, Kirschallee 1, D-53115 Bonn, Germany.
| | | | | | | | | |
Collapse
|
23
|
Blancaflor EB, Wang YS, Motes CM. Organization and function of the actin cytoskeleton in developing root cells. INTERNATIONAL REVIEW OF CYTOLOGY 2006; 252:219-64. [PMID: 16984819 DOI: 10.1016/s0074-7696(06)52004-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The actin cytoskeleton is a highly dynamic structure, which mediates various cellular functions in large part through accessory proteins that tilt the balance between monomeric G-actin and filamentous actin (F-actin) or by facilitating interactions between actin and the plasma membrane, microtubules, and other organelles. Roots have become an attractive model to study actin in plant development because of their simple anatomy and accessibility of some root cell types such as root hairs for microscopic analyses. Roots also exhibit a remarkable developmental plasticity and possess a delicate sensory system that is easily manipulated, so that one can design experiments addressing a range of important biological questions. Many facets of root development can be regulated by the diverse actin network found in the various root developmental regions. Various molecules impinge on this actin scaffold to define how a particular root cell type grows or responds to a specific environmental signal. Although advances in genomics are leading the way toward elucidating actin function in roots, more significant strides will be realized when such tools are combined with improved methodologies for accurately depicting how actin is organized in plant cells.
Collapse
Affiliation(s)
- Elison B Blancaflor
- Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401, USA
| | | | | |
Collapse
|