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Zhuang Y, Wang Y, Jiao C, Shang Z, Huang S. Arabidopsis VILLIN5 bundles actin filaments using a novel mechanism. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024. [PMID: 39093617 DOI: 10.1111/tpj.16956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Revised: 07/10/2024] [Accepted: 07/19/2024] [Indexed: 08/04/2024]
Abstract
Being a bona fide actin bundler, Arabidopsis villin5 (VLN5) plays a crucial role in regulating actin stability and organization within pollen tubes. Despite its significance, the precise mechanism through which VLN5 bundles actin filaments has remained elusive. Through meticulous deletion analysis, we have unveiled that the link between gelsolin repeat 6 (G6) and the headpiece domain (VHP), rather than VHP itself, is indispensable for VLN5-mediated actin bundling. Further refinement of this region has pinpointed a critical sequence spanning from Val763 to Ser823, essential for VLN5's actin-bundling activity. Notably, the absence of Val763-Ser823 in VLN5 results in decreased filamentous decoration within pollen tubes and a diminished ability to rescue actin bundling defects in vln2vln5 mutant pollen tubes compared to intact VLN5. Moreover, our findings highlight that the Val763-Ser823 sequence harbors a binding site for F-actin, suggesting that this linker-based F-actin binding site, in conjunction with the F-actin binding site localized in G1-G6, enables a single VLN5 to concurrently bind to two adjacent actin filaments. Therefore, our study unveils a novel mechanism by which VLN5 bundles actin filaments.
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Affiliation(s)
- Yuhui Zhuang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
- College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Yingjie Wang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Cuixia Jiao
- College of Life Sciences, Hebei Normal University, Shijiazhuang, 050016, China
| | - Zhonglin Shang
- College of Life Sciences, Hebei Normal University, Shijiazhuang, 050016, China
| | - Shanjin Huang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
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2
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Qian D, Li T, Chen S, Wan D, He Y, Zheng C, Li J, Sun Z, Li J, Sun J, Niu Y, Li H, Wang M, Niu Y, Yang Y, An L, Xiang Y. Evolution of the thermostability of actin-depolymerizing factors enhances the adaptation of pollen germination to high temperature. THE PLANT CELL 2024; 36:881-898. [PMID: 37941457 PMCID: PMC10980419 DOI: 10.1093/plcell/koad280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 09/14/2023] [Accepted: 10/09/2023] [Indexed: 11/10/2023]
Abstract
Double fertilization in many flowering plants (angiosperms) often occurs during the hot summer season, but the mechanisms that enable angiosperms to adapt specifically to high temperatures are largely unknown. The actin cytoskeleton is essential for pollen germination and the polarized growth of pollen tubes, yet how this process responds to high temperatures remains unclear. Here, we reveal that the high thermal stability of 11 Arabidopsis (Arabidopsis thaliana) actin-depolymerizing factors (ADFs) is significantly different: ADFs that specifically accumulate in tip-growing cells (pollen and root hairs) exhibit high thermal stability. Through ancestral protein reconstruction, we found that subclass II ADFs (expressed specifically in pollen) have undergone a dynamic wave-like evolution of the retention, loss, and regeneration of thermostable sites. Additionally, the sites of AtADF7 with high thermal stability are conserved in ADFs specific to angiosperm pollen. Moreover, the high thermal stability of ADFs is required to regulate actin dynamics and turnover at high temperatures to promote pollen germination. Collectively, these findings suggest strategies for the adaptation of sexual reproduction to high temperature in angiosperms at the cell biology level.
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Affiliation(s)
- Dong Qian
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Tian Li
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Shuyuan Chen
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Dongshi Wan
- State Key Laboratory of Grassland Agro-Ecosystem, College of Ecology, Lanzhou University, Lanzhou 730000, China
| | - Yongxing He
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Chen Zheng
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Jiajing Li
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education, College of Life Science, Beijing Normal University, Beijing 100875, China
| | - Zhenping Sun
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education, College of Life Science, Beijing Normal University, Beijing 100875, China
| | - Jiejie Li
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education, College of Life Science, Beijing Normal University, Beijing 100875, China
| | - Junxia Sun
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Yingzhi Niu
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Hongxia Li
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Muxuan Wang
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Yue Niu
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Yang Yang
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Lizhe An
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Yun Xiang
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
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3
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Ruan H, Wang T, Ren H, Zhang Y. AtFH5-labeled secretory vesicles-dependent calcium oscillation drives exocytosis and stepwise bulge during pollen germination. Cell Rep 2023; 42:113319. [PMID: 37897722 DOI: 10.1016/j.celrep.2023.113319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2023] [Revised: 09/11/2023] [Accepted: 10/06/2023] [Indexed: 10/30/2023] Open
Abstract
Pollen germination is an essential step for delivering sperm cells to the embryo sac for double fertilization in flowering plants. The cytosolic Ca2+ concentration ([Ca2+]cyt) and vesicle dynamics are critical for pollen germination, but their potential correlation in pollen grains is not fully understood. Here, we report that [Ca2+]cyt oscillates periodically at the prospective germination sites during pollen germination. The [Ca2+]cyt is mainly from extracellular Ca2+ ([Ca2+]ext) influx, which implicates the Ca2+-permeable ion channel cyclic nucleotide-gated channel 18 (CNGC18). The [Ca2+]cyt oscillations spatiotemporally correlate with the accumulation of secretory vesicles labeled by a formin protein AtFH5, and disruption of vesicle accumulation inhibits the [Ca2+]cyt oscillations. In turn, the [Ca2+]cyt oscillations promote exocytosis, which leads to stepwise cell extension during pollen germination. Together, these data provide a timeline of vesicle dynamics, calcium oscillation, and exocytosis during pollen germination and highlight the importance of the correlation of these events for pollen germination.
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Affiliation(s)
- Huaqiang Ruan
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education, College of Life Science, Beijing Normal University, Beijing 100875, China; Center for Biological Science and Technology, Zhuhai-Macao Biotechnology Joint Laboratory, Advanced Institute of Natural Science, Beijing Normal University, Zhuhai 519087, China
| | - Ting Wang
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education, College of Life Science, Beijing Normal University, Beijing 100875, China
| | - Haiyun Ren
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education, College of Life Science, Beijing Normal University, Beijing 100875, China; Center for Biological Science and Technology, Zhuhai-Macao Biotechnology Joint Laboratory, Advanced Institute of Natural Science, Beijing Normal University, Zhuhai 519087, China.
| | - Yi Zhang
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education, College of Life Science, Beijing Normal University, Beijing 100875, China.
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4
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Stephan OOH. Effects of environmental stress factors on the actin cytoskeleton of fungi and plants: Ionizing radiation and ROS. Cytoskeleton (Hoboken) 2023; 80:330-355. [PMID: 37066976 DOI: 10.1002/cm.21758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 03/20/2023] [Accepted: 03/29/2023] [Indexed: 04/18/2023]
Abstract
Actin is an abundant and multifaceted protein in eukaryotic cells that has been detected in the cytoplasm as well as in the nucleus. In cooperation with numerous interacting accessory-proteins, monomeric actin (G-actin) polymerizes into microfilaments (F-actin) which constitute ubiquitous subcellular higher order structures. Considering the extensive spatial dimensions and multifunctionality of actin superarrays, the present study analyses the issue if and to what extent environmental stress factors, specifically ionizing radiation (IR) and reactive oxygen species (ROS), affect the cellular actin-entity. In that context, this review particularly surveys IR-response of fungi and plants. It examines in detail which actin-related cellular constituents and molecular pathways are influenced by IR and related ROS. This comprehensive survey concludes that the general integrity of the total cellular actin cytoskeleton is a requirement for IR-tolerance. Actin's functions in genome organization and nuclear events like chromatin remodeling, DNA-repair, and transcription play a key role. Beyond that, it is highly significant that the macromolecular cytoplasmic and cortical actin-frameworks are affected by IR as well. In response to IR, actin-filament bundling proteins (fimbrins) are required to stabilize cables or patches. In addition, the actin-associated factors mediating cellular polarity are essential for IR-survivability. Moreover, it is concluded that a cellular homeostasis system comprising ROS, ROS-scavengers, NADPH-oxidases, and the actin cytoskeleton plays an essential role here. Consequently, besides the actin-fraction which controls crucial genome-integrity, also the portion which facilitates orderly cellular transport and polarized growth has to be maintained in order to survive IR.
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Affiliation(s)
- Octavian O H Stephan
- Department of Biology, Friedrich-Alexander University of Erlangen-Nuremberg, Erlangen, Bavaria, 91058, Germany
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Zhang R, Xu Y, Yi R, Shen J, Huang S. Actin cytoskeleton in the control of vesicle transport, cytoplasmic organization, and pollen tube tip growth. PLANT PHYSIOLOGY 2023; 193:9-25. [PMID: 37002825 DOI: 10.1093/plphys/kiad203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 03/08/2023] [Accepted: 03/17/2023] [Indexed: 06/19/2023]
Abstract
Pollen tubes extend rapidly via tip growth. This process depends on a dynamic actin cytoskeleton, which has been implicated in controlling organelle movements, cytoplasmic streaming, vesicle trafficking, and cytoplasm organization in pollen tubes. In this update review, we describe the progress in understanding the organization and regulation of the actin cytoskeleton and the function of the actin cytoskeleton in controlling vesicle traffic and cytoplasmic organization in pollen tubes. We also discuss the interplay between ion gradients and the actin cytoskeleton that regulates the spatial arrangement and dynamics of actin filaments and the organization of the cytoplasm in pollen tubes. Finally, we describe several signaling components that regulate actin dynamics in pollen tubes.
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Affiliation(s)
- Ruihui Zhang
- National Key Laboratory of Crop Genetic Improvement, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Yanan Xu
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Ran Yi
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Jiangfeng Shen
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Shanjin Huang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
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6
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Tullis JE, Bayer KU. Distinct synaptic pools of DAPK1 differentially regulate activity-dependent synaptic CaMKII accumulation. iScience 2023; 26:106723. [PMID: 37216104 PMCID: PMC10192646 DOI: 10.1016/j.isci.2023.106723] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 03/18/2023] [Accepted: 04/19/2023] [Indexed: 05/24/2023] Open
Abstract
The death-associated protein kinase 1 (DAPK1) regulates the synaptic movement of the Ca2+/calmodulin (CaM)-dependent protein kinase II (CaMKII). Synaptic CaMKII accumulation is mediated via binding to the NMDA-receptor subunit GluN2B and is required for long-term potentiation (LTP). By contrast, long-term depression (LTD) instead requires specific suppression of this movement, which is mediated by competitive DAPK1 binding to GluN2B. We find here that DAPK1 localizes to synapses via two distinct mechanisms: basal localization requires F-actin, but retention of DAPK1 at synapses during LTD requires an additional binding mode, likely to GluN2B. While F-actin binding mediates DAPK1 enrichment at synapses, it is not sufficient to suppress synaptic CaMKII movement. However, it is a prerequisite that enables the additional LTD-specific binding mode of DAPK1, which in turn mediates suppression of the CaMKII movement. Thus, both modes of synaptic DAPK1 localization work together to regulate synaptic CaMKII localization and thereby synaptic plasticity.
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Affiliation(s)
- Jonathan E. Tullis
- Department of Pharmacology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - K. Ulrich Bayer
- Department of Pharmacology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
- Program in Neuroscience, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
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7
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Wang Q, Xu Y, Zhao S, Jiang Y, Yi R, Guo Y, Huang S. Activation of actin-depolymerizing factor by CDPK16-mediated phosphorylation promotes actin turnover in Arabidopsis pollen tubes. PLoS Biol 2023; 21:e3002073. [PMID: 37011088 PMCID: PMC10101649 DOI: 10.1371/journal.pbio.3002073] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 04/13/2023] [Accepted: 03/11/2023] [Indexed: 04/05/2023] Open
Abstract
As the stimulus-responsive mediator of actin dynamics, actin-depolymerizing factor (ADF)/cofilin is subject to tight regulation. It is well known that kinase-mediated phosphorylation inactivates ADF/cofilin. Here, however, we found that the activity of Arabidopsis ADF7 is enhanced by CDPK16-mediated phosphorylation. We found that CDPK16 interacts with ADF7 both in vitro and in vivo, and it enhances ADF7-mediated actin depolymerization and severing in vitro in a calcium-dependent manner. Accordingly, the rate of actin turnover is reduced in cdpk16 pollen and the amount of actin filaments increases significantly at the tip of cdpk16 pollen tubes. CDPK16 phosphorylates ADF7 at Serine128 both in vitro and in vivo, and the phospho-mimetic mutant ADF7S128D has enhanced actin-depolymerizing activity compared to ADF7. Strikingly, we found that failure in the phosphorylation of ADF7 at Ser128 impairs its function in promoting actin turnover in vivo, which suggests that this phospho-regulation mechanism is biologically significant. Thus, we reveal that CDPK16-mediated phosphorylation up-regulates ADF7 to promote actin turnover in pollen.
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Affiliation(s)
- Qiannan Wang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Yanan Xu
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Shuangshuang Zhao
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, China
- Key Laboratory of Plant Stress, Life Science College, Shandong Normal University, Jinan, China
| | - Yuxiang Jiang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Ran Yi
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Yan Guo
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Shanjin Huang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
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8
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Macromolecular crowding regulates matrix composition and gene expression in human gingival fibroblast cultures. Sci Rep 2023; 13:2047. [PMID: 36739306 PMCID: PMC9899282 DOI: 10.1038/s41598-023-29252-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 02/01/2023] [Indexed: 02/06/2023] Open
Abstract
Standard cell cultures are performed in aqueous media with a low macromolecule concentration compared to tissue microenvironment. In macromolecular crowding (MMC) experiments, synthetic polymeric crowders are added into cell culture media to better mimic macromolecule concentrations found in vivo. However, their effect on cultured cells is incompletely understood and appears context-dependent. Here we show using human gingival fibroblasts, a cell type associated with fast and scarless wound healing, that MMC (standard medium supplemented with Ficoll 70/400) potently modulates fibroblast phenotype and extracellular matrix (ECM) composition compared to standard culture media (nMMC) over time. MMC significantly reduced cell numbers, but increased accumulation of collagen I, cellular fibronectin, and tenascin C, while suppressing level of SPARC (Secreted Protein Acidic and Cysteine Rich). Out of the 75 wound healing and ECM related genes studied, MMC significantly modulated expression of 25 genes compared to nMMC condition. MMC also suppressed myofibroblast markers and promoted deposition of basement membrane molecules collagen IV, laminin 1, and expression of LAMB3 (Laminin Subunit Beta 3) gene. In cell-derived matrices produced by a novel decellularization protocol, the altered molecular composition of MMC matrices was replicated. Thus, MMC may improve cell culture models for research and provide novel approaches for regenerative therapy.
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9
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Langer G, Probert I, Cox MB, Taylor A, Harper GM, Brownlee C, Wheeler G. The Effect of cytoskeleton inhibitors on coccolith morphology in Coccolithus braarudii and Scyphosphaera apsteinii. JOURNAL OF PHYCOLOGY 2023; 59:87-96. [PMID: 36380706 DOI: 10.1111/jpy.13303] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 09/20/2022] [Indexed: 05/24/2023]
Abstract
The calcite platelets of coccolithophores (Haptophyta), the coccoliths, are among the most elaborate biomineral structures. How these unicellular algae accomplish the complex morphogenesis of coccoliths is still largely unknown. It has long been proposed that the cytoskeleton plays a central role in shaping the growing coccoliths. Previous studies have indicated that disruption of the microtubule network led to defects in coccolith morphogenesis in Emiliania huxleyi and Coccolithus braarudii. Disruption of the actin network also led to defects in coccolith morphology in E. huxleyi, but its impact on coccolith morphology in C. braarudii was unclear, as coccolith secretion was largely inhibited under the conditions used. A more detailed examination of the role of actin and microtubule networks is therefore required to address the wider role of the cytoskeleton in coccolith morphogenesis. In this study, we have examined coccolith morphology in C. braarudii and Scyphosphaera apsteinii following treatment with the microtubule inhibitors vinblastine and colchicine (S. apsteinii only) and the actin inhibitor cytochalasin B. We found that all cytoskeleton inhibitors induced coccolith malformations, strongly suggesting that both microtubules and actin filaments are instrumental in morphogenesis. By demonstrating the requirement for the microtubule and actin networks in coccolith morphogenesis in diverse species, our results suggest that both of these cytoskeletal elements are likely to play conserved roles in defining coccolith morphology.
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Affiliation(s)
- Gerald Langer
- Marine Biological Association, The Laboratory, Citadel Hill, Plymouth, PL1 2PB, UK
| | - Ian Probert
- Station Biologique de Roscoff, 29680, Roscoff, France
| | - Madison B Cox
- Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, North Carolina, 28403-591, USA
| | - Alison Taylor
- Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, North Carolina, 28403-591, USA
| | - Glenn M Harper
- Plymouth Electron Microscopy Centre, University of Plymouth, Plymouth, PL4 8AA, UK
| | - Colin Brownlee
- Marine Biological Association, The Laboratory, Citadel Hill, Plymouth, PL1 2PB, UK
- School of Ocean and Earth Science, University of Southampton, Southampton, SO14 3ZH, UK
| | - Glen Wheeler
- Marine Biological Association, The Laboratory, Citadel Hill, Plymouth, PL1 2PB, UK
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10
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Gu S, Tzingounis AV, Lykotrafitis G. Differential Control of Small-conductance Calcium-activated Potassium Channel Diffusion by Actin in Different Neuronal Subcompartments. FUNCTION 2023; 4:zqad018. [PMID: 37168495 PMCID: PMC10165553 DOI: 10.1093/function/zqad018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 04/13/2023] [Accepted: 04/19/2023] [Indexed: 05/13/2023] Open
Abstract
Small-conductance calcium-activated potassium (SK) channels show a ubiquitous distribution on neurons, in both somatodendritic and axonal regions. SK channels are associated with neuronal activity regulating action potential frequency, dendritic excitability, and synaptic plasticity. Although the physiology of SK channels and the mechanisms that control their surface expression levels have been investigated extensively, little is known about what controls SK channel diffusion in the neuronal plasma membrane. This aspect is important, as the diffusion of SK channels at the surface may control their localization and proximity to calcium channels, hence increasing the likelihood of SK channel activation by calcium. In this study, we successfully investigated the diffusion of SK channels labeled with quantum dots on human embryonic kidney cells and dissociated hippocampal neurons by combining a single-particle tracking method with total internal reflection fluorescence microscopy. We observed that actin filaments interfere with SK mobility, decreasing their diffusion coefficient. We also found that during neuronal maturation, SK channel diffusion was gradually inhibited in somatodendritic compartments. Importantly, we observed that axon barriers formed at approximately days in vitro 6 and restricted the diffusion of SK channels on the axon initial segment (AIS). However, after neuron maturation, SK channels on the AIS were strongly immobilized, even after disruption of the actin network, suggesting that crowding may cause this effect. Altogether, our work provides insight into how SK channels diffuse on the neuronal plasma membrane and how actin and membrane crowding impacts SK channel diffusion.
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Affiliation(s)
- Shiju Gu
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06269, USA
| | - Anastasios V Tzingounis
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06269, USA
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT 06269, USA
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11
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Spatola Rossi T, Pain C, Botchway SW, Kriechbaumer V. FRET-FLIM to Determine Protein Interactions and Membrane Topology of Enzyme Complexes. Curr Protoc 2022; 2:e598. [PMID: 36300920 DOI: 10.1002/cpz1.598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Determining protein-protein interactions is vital for gaining knowledge on cellular and metabolic processes including enzyme complexes and metabolons. Förster resonance energy transfer with fluorescence lifetime imaging microscopy (FRET-FLIM) is an advanced imaging methodology that allows for the quantitative detection of protein-protein interactions. In this method, proteins of interest for interaction studies are fused to different fluorophores such as enhanced green fluorescent protein (eGFP; donor molecule) and monomeric red fluorescent protein (mRFP; acceptor molecule). Energy transfer between the two fluorophore groups can only occur efficiently when the proteins of interest are in close physical proximity, around ≤10 nm, and therefore are most likely interacting. FRET-FLIM measures the decrease in excited-state lifetime of the donor fluorophore (eGFP) with and without the presence of the acceptor (mRFP) and can therefore give information on protein-protein interactions and the membrane topology of the tested protein. Here we describe the production of fluorescent protein fusions for FRET-FLIM analysis in tobacco leaf epidermal cells using Agrobacterium-mediated plant transformation and a FRET-FLIM data acquisition and analysis protocol in plant cells. These protocols are applicable and can be adapted for both membrane and soluble proteins in different cellular localizations. © 2022 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Protein expression in tobacco leaf cells via transient Agrobacterium-mediated plant transformation Basic Protocol 2: FRET-FLIM data acquisition and analysis.
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Affiliation(s)
- Tatiana Spatola Rossi
- Endomembrane Structure and Function Research Group, Biological and Medical Sciences, Oxford Brookes University, Oxford, UK
| | - Charlotte Pain
- Endomembrane Structure and Function Research Group, Biological and Medical Sciences, Oxford Brookes University, Oxford, UK
| | - Stanley W Botchway
- Central Laser Facility, Science and Technology Facilities Council (STFC) Rutherford Appleton Laboratory, Research Complex at Harwell, Didcot, UK
| | - Verena Kriechbaumer
- Endomembrane Structure and Function Research Group, Biological and Medical Sciences, Oxford Brookes University, Oxford, UK
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12
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Brueggeman JM, Windham IA, Nebenführ A. Nuclear movement in growing Arabidopsis root hairs involves both actin filaments and microtubules. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:5388-5399. [PMID: 35554524 DOI: 10.1093/jxb/erac207] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 05/09/2022] [Indexed: 06/15/2023]
Abstract
Nuclear migration during growth and development is a conserved phenomenon among many eukaryotic species. In Arabidopsis, movement of the nucleus is important for root hair growth, but the detailed mechanism behind this movement is not well known. Previous studies in different cell types have reported that the myosin XI-I motor protein is responsible for this nuclear movement by attaching to the nuclear transmembrane protein complex WIT1/WIT2. Here, we analyzed nuclear movement in growing root hairs of wild-type, myosin xi-i, and wit1 wit2 Arabidopsis lines in the presence of actin and microtubule-disrupting inhibitors to determine the individual effects of actin filaments and microtubules on nuclear movement. We discovered that forward nuclear movement during root hair growth can occur in the absence of myosin XI-I, suggesting the presence of an alternative actin-based mechanism that mediates rapid nuclear displacements. By quantifying nuclear movements with high temporal resolution during the initial phase of inhibitor treatment, we determined that microtubules work to dampen erratic nuclear movements during root hair growth. We also observed microtubule-dependent backwards nuclear movement when actin filaments were impaired in the absence of myosin XI-I, indicating the presence of complex interactions between the cytoskeletal arrays during nuclear movements in growing root hairs.
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Affiliation(s)
- Justin M Brueggeman
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, USA
| | - Ian A Windham
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, USA
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC, USA
| | - Andreas Nebenführ
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, USA
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13
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Pain C, Tolmie F, Wojcik S, Wang P, Kriechbaumer V. intER-ACTINg: the structure and dynamics of ER and actin are interlinked. J Microsc 2022. [PMID: 35985796 DOI: 10.1111/jmi.13139] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 08/09/2022] [Accepted: 08/10/2022] [Indexed: 11/30/2022]
Abstract
The actin cytoskeleton is the driver of gross ER remodelling and the movement and positioning of other membrane-bound organelles such as Golgi bodies. Rapid ER membrane remodelling is a feature of most plant cells and is important for normal cellular processes, including targeted secretion, immunity and signalling. Modifications to the actin cytoskeleton, through pharmacological agents such as Latrunculin B and phalloidin, or disruption of normal myosin function also affect ER structure and/or dynamics. Here, we investigate the impact of changes in the actin cytoskeleton on structure and dynamics on the ER as well as in return the impact of modified ER structure on the architecture of the actin cytoskeleton. By expressing actin markers that affect actin dynamics, or expressing of ER-shaping proteins that influence ER architecture, we found that the structure of ER-actin networks is closely inter-related; affecting one component is likely to have a direct effect on the other. Therefore, our results indicate that a complicated regulatory machinery and cross-talk between these two structures must exist in plants to co-ordinate the function of ER-actin network during multiple subcellular processes. In addition, when considering organelle structure and dynamics, the choice of actin marker is essential in preventing off-target organelle structure and dynamics modifications. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Charlotte Pain
- Plant Cell Biology, Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, OX3 0BP, UK
| | - Frances Tolmie
- Plant Cell Biology, Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, OX3 0BP, UK
| | - Stefan Wojcik
- Plant Cell Biology, Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, OX3 0BP, UK
| | - Pengwei Wang
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Science, Huazhong Agricultural University, Wuhan, 430070, China
| | - Verena Kriechbaumer
- Plant Cell Biology, Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, OX3 0BP, UK
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14
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Jiang D, He Y, Zhou X, Cao Z, Pang L, Zhong S, Jiang L, Li R. Arabidopsis HOPS subunit VPS41 carries out plant-specific roles in vacuolar transport and vegetative growth. PLANT PHYSIOLOGY 2022; 189:1416-1434. [PMID: 35417008 PMCID: PMC9237685 DOI: 10.1093/plphys/kiac167] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Accepted: 02/25/2022] [Indexed: 05/27/2023]
Abstract
The homotypic fusion and protein sorting (HOPS) complex is a conserved, multi-subunit tethering complex in eukaryotic cells. In yeast and mammalian cells, the HOPS subunit vacuolar protein sorting-associated protein 41 (VPS41) is recruited to late endosomes after Ras-related protein 7 (Rab7) activation and is essential for vacuole fusion. However, whether VPS41 plays conserved roles in plants is not clear. Here, we demonstrate that in the model plant Arabidopsis (Arabidopsis thaliana), VPS41 localizes to distinct condensates in root cells in addition to its reported localization at the tonoplast. The formation of condensates does not rely on the known upstream regulators but depends on VPS41 self-interaction and is essential for vegetative growth regulation. Genetic evidence indicates that VPS41 is required for both homotypic vacuole fusion and cargo sorting from the adaptor protein complex 3, Rab5, and Golgi-independent pathways but is dispensable for the Rab7 cargo inositol transporter 1. We also show that VPS41 has HOPS-independent functions in vacuolar transport. Taken together, our findings indicate that Arabidopsis VPS41 is a unique subunit of the HOPS complex that carries out plant-specific roles in both vacuolar transport and developmental regulation.
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Affiliation(s)
- Dong Jiang
- Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, School of Life Sciences, Institute of Plant and Food Science, Southern University of Science and Technology, Shenzhen 518055, China
| | - Yilin He
- School of Life Sciences, Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Xiangui Zhou
- Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, School of Life Sciences, Institute of Plant and Food Science, Southern University of Science and Technology, Shenzhen 518055, China
| | - Zhiran Cao
- Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, School of Life Sciences, Institute of Plant and Food Science, Southern University of Science and Technology, Shenzhen 518055, China
| | - Lei Pang
- Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, School of Life Sciences, Institute of Plant and Food Science, Southern University of Science and Technology, Shenzhen 518055, China
| | - Sheng Zhong
- State Key Laboratory for Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences at the College of Life Sciences, Peking University, Beijing 100871, China
| | - Liwen Jiang
- School of Life Sciences, Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
- CUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen 518172, China
| | - Ruixi Li
- Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, School of Life Sciences, Institute of Plant and Food Science, Southern University of Science and Technology, Shenzhen 518055, China
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15
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Liu N, Wang W, He C, Luo H, An B, Wang Q. NADPH Oxidases Play a Role in Pathogenicity via the Regulation of F-Actin Organization in Colletotrichum gloeosporioides. Front Cell Infect Microbiol 2022; 12:845133. [PMID: 35782153 PMCID: PMC9240266 DOI: 10.3389/fcimb.2022.845133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Accepted: 05/16/2022] [Indexed: 11/29/2022] Open
Abstract
Multiunit-flavoenzyme NADPH oxidases (NOXs) play multiple roles in living cells via regulating signaling pathways. In several phytopathogenic fungi, NOXs are required for the polarized growth of hyphal tips and pathogenicity to host plants, but the possible mechanisms are still elusive. In our previous study, CgNOXA, CgNOXB, and CgNOXR were identified as components of the NOX complex in Colletotrichum gloeosporioides. The growth and the inoculation assays revealed that CgNOXA/B and CgNOXR regulate vegetative growth and are required for the full pathogenicity of C. gloeosporioides to Hevea leaves. We further demonstrated that the vital roles of CgNOXB and CgNOXR in appressorium formation and the development of invasion hyphae account for their functions in pathogenicity. Moreover, CgNOXB and CgNOXR regulate the production and distribution of ROS in hyphal tips and appressoria, control the specialized remodeling of F-actin in hyphal tips and appressoria, and are involved in fungal cell wall biosynthesis. Taken together, our findings highlight the role of NOXs in fungal pathogenicity through the organization of the actin cytoskeleton.
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Affiliation(s)
- Na Liu
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource, College of Tropical Crops, Hainan University, Haikou, China
- Sanya Nanfan Research Institute of Hainan University, Hainan Yazhou Bay Seed Laboratory, Sanya, China
| | - Wenfeng Wang
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource, College of Tropical Crops, Hainan University, Haikou, China
| | - Chaozu He
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource, College of Tropical Crops, Hainan University, Haikou, China
- Sanya Nanfan Research Institute of Hainan University, Hainan Yazhou Bay Seed Laboratory, Sanya, China
| | - Hongli Luo
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource, College of Tropical Crops, Hainan University, Haikou, China
- Sanya Nanfan Research Institute of Hainan University, Hainan Yazhou Bay Seed Laboratory, Sanya, China
| | - Bang An
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource, College of Tropical Crops, Hainan University, Haikou, China
- Sanya Nanfan Research Institute of Hainan University, Hainan Yazhou Bay Seed Laboratory, Sanya, China
| | - Qiannan Wang
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource, College of Tropical Crops, Hainan University, Haikou, China
- Sanya Nanfan Research Institute of Hainan University, Hainan Yazhou Bay Seed Laboratory, Sanya, China
- *Correspondence: Qiannan Wang,
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16
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Çetinbaş-Genç A, Conti V, Cai G. Let's shape again: the concerted molecular action that builds the pollen tube. PLANT REPRODUCTION 2022; 35:77-103. [PMID: 35041045 DOI: 10.1007/s00497-022-00437-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 01/06/2022] [Indexed: 06/14/2023]
Abstract
The pollen tube is being subjected to control by a complex network of communication that regulates its shape and the misfunction of a single component causes specific deformations. In flowering plants, the pollen tube is a tubular extension of the pollen grain required for successful sexual reproduction. Indeed, maintaining the unique shape of the pollen tube is essential for the pollen tube to approach the embryo sac. Many processes and molecules (such as GTPase activity, phosphoinositides, Ca2+ gradient, distribution of reactive oxygen species and nitric oxide, nonuniform pH values, organization of the cytoskeleton, balance between exocytosis and endocytosis, and cell wall structure) play key and coordinated roles in maintaining the cylindrical shape of pollen tubes. In addition, the above factors must also interact with each other so that the cell shape is maintained while the pollen tube follows chemical signals in the pistil that guide it to the embryo sac. Any intrinsic changes (such as erroneous signals) or extrinsic changes (such as environmental stresses) can affect the above factors and thus fertilization by altering the tube morphology. In this review, the processes and molecules that enable the development and maintenance of the unique shape of pollen tubes in angiosperms are presented emphasizing their interaction with specific tube shape. Thus, the purpose of the review is to investigate whether specific deformations in pollen tubes can help us to better understand the mechanism underlying pollen tube shape.
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Affiliation(s)
- Aslıhan Çetinbaş-Genç
- Department of Biology, Marmara University, Göztepe Campus, 34722, Kadıköy, Istanbul, Turkey.
| | - Veronica Conti
- Department of Life Sciences, University of Siena, via Mattioli 4, 53100, Siena, Italy
| | - Giampiero Cai
- Department of Life Sciences, University of Siena, via Mattioli 4, 53100, Siena, Italy
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17
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Jiang Y, Lu Q, Huang S. Functional non-equivalence of pollen ADF isovariants in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2022; 110:1068-1081. [PMID: 35233873 DOI: 10.1111/tpj.15723] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 02/24/2022] [Accepted: 02/26/2022] [Indexed: 06/14/2023]
Abstract
ADF/cofilin is a central regulator of actin dynamics. We previously demonstrated that two closely related Arabidopsis class IIa ADF isovariants, ADF7 and ADF10, are involved in the enhancement of actin turnover in pollen, but whether they have distinct functions remains unknown. Here, we further demonstrate that they exhibit distinct functions in regulating actin turnover both in vitro and in vivo. We found that ADF7 binds to ADP-G-actin with lower affinity, and severs and depolymerizes actin filaments less efficiently in vitro than ADF10. Accordingly, in pollen grains, ADF7 more extensively decorates actin filaments and is less freely distributed in the cytoplasm compared to ADF10. We further demonstrate that ADF7 and ADF10 show distinct intracellular localizations during pollen germination, and they have non-equivalent functions in promoting actin turnover in pollen. We thus propose that cooperation and labor division of ADF7 and ADF10 enable pollen cells to achieve exquisite control of the turnover of different actin structures to meet different cellular needs.
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Affiliation(s)
- Yuxiang Jiang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Qiaonan Lu
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Shanjin Huang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
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18
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Zeng J, Xi J, Li B, Yan X, Dai Y, Wu Y, Xiao Y, Pei Y, Zhang M. Microtubules play a crucial role in regulating actin organization and cell initiation in cotton fibers. PLANT CELL REPORTS 2022; 41:1059-1073. [PMID: 35217893 DOI: 10.1007/s00299-022-02837-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 01/26/2022] [Indexed: 06/14/2023]
Abstract
Dynamic organization of actin and microtubule cytoskeletons directs a distinct expansion behavior of cotton fiber initiation from cell elongation. Cotton fibers are highly elongated single cells derived from the ovule epidermis. Although actin and microtubule (MT) cytoskeletons have been implicated in cell elongation and secondary wall deposition, their roles in fiber initiation is poorly understood. Here, we used fluorescent probes and pharmacological approaches to study the roles of these cytoskeletal components during cotton fiber initiation. Both cytoskeletons align along the growth axis in initiating fibers. The dorsal view of ovules shows that unlike the fine actin filaments (AFs) in nonfiber cells, the AFs in fiber cells are dense and bundled. MTs are randomized in fiber cells and well-ordered in nonfiber cells. The pharmacological experiments revealed that the depolymerization of AFs and MTs assisted fiber initiation. Both AF stabilization and depolymerization inhibited fiber elongation. In contrast, the proper depolymerization of MTs promoted cell elongation, although the MT-stabilizing drug consistently resulted in a negative effect. Notably, we found that the organization of AFs was correlated with MT dynamics. Stabilizing the MTs by taxol treatment promoted the formation of AF bundles (in fiber initials) and transversely aligned AFs (in elongating fibers), whereas depolymerizing the MTs by oryzalin treatment promoted the fragmentation of AFs. Collectively, our data indicates that MTs plays a crucial role in regulating AF organization and early development of cotton fibers.
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Affiliation(s)
- Jianyan Zeng
- Biotechnology Research Center, Southwest University, No. 2 Tiansheng Road, Beibei, Chongqing, 400715, People's Republic of China
- Academy of Agricultural Sciences, Southwest University, No. 2 Tiansheng Road, Beibei, Chongqing, 400715, People's Republic of China
| | - Jing Xi
- Biotechnology Research Center, Southwest University, No. 2 Tiansheng Road, Beibei, Chongqing, 400715, People's Republic of China
- Academy of Agricultural Sciences, Southwest University, No. 2 Tiansheng Road, Beibei, Chongqing, 400715, People's Republic of China
- Chongqing Key Laboratory of Plant Resource Conservation and Germplasm Innovation, No. 2 Tiansheng Road, Beibei, Chongqing, 400715, People's Republic of China
| | - Baoxia Li
- Biotechnology Research Center, Southwest University, No. 2 Tiansheng Road, Beibei, Chongqing, 400715, People's Republic of China
- Academy of Agricultural Sciences, Southwest University, No. 2 Tiansheng Road, Beibei, Chongqing, 400715, People's Republic of China
- Chongqing Key Laboratory of Plant Resource Conservation and Germplasm Innovation, No. 2 Tiansheng Road, Beibei, Chongqing, 400715, People's Republic of China
| | - Xingying Yan
- Biotechnology Research Center, Southwest University, No. 2 Tiansheng Road, Beibei, Chongqing, 400715, People's Republic of China
- Academy of Agricultural Sciences, Southwest University, No. 2 Tiansheng Road, Beibei, Chongqing, 400715, People's Republic of China
| | - Yonglu Dai
- Biotechnology Research Center, Southwest University, No. 2 Tiansheng Road, Beibei, Chongqing, 400715, People's Republic of China
- Academy of Agricultural Sciences, Southwest University, No. 2 Tiansheng Road, Beibei, Chongqing, 400715, People's Republic of China
| | - Yiping Wu
- Biotechnology Research Center, Southwest University, No. 2 Tiansheng Road, Beibei, Chongqing, 400715, People's Republic of China
- Academy of Agricultural Sciences, Southwest University, No. 2 Tiansheng Road, Beibei, Chongqing, 400715, People's Republic of China
| | - Yuehua Xiao
- Biotechnology Research Center, Southwest University, No. 2 Tiansheng Road, Beibei, Chongqing, 400715, People's Republic of China
- Academy of Agricultural Sciences, Southwest University, No. 2 Tiansheng Road, Beibei, Chongqing, 400715, People's Republic of China
| | - Yan Pei
- Biotechnology Research Center, Southwest University, No. 2 Tiansheng Road, Beibei, Chongqing, 400715, People's Republic of China
- Academy of Agricultural Sciences, Southwest University, No. 2 Tiansheng Road, Beibei, Chongqing, 400715, People's Republic of China
| | - Mi Zhang
- Biotechnology Research Center, Southwest University, No. 2 Tiansheng Road, Beibei, Chongqing, 400715, People's Republic of China.
- Academy of Agricultural Sciences, Southwest University, No. 2 Tiansheng Road, Beibei, Chongqing, 400715, People's Republic of China.
- Chongqing Key Laboratory of Plant Resource Conservation and Germplasm Innovation, No. 2 Tiansheng Road, Beibei, Chongqing, 400715, People's Republic of China.
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19
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Identification and characterization of profilin gene family in rice. ELECTRON J BIOTECHN 2021. [DOI: 10.1016/j.ejbt.2021.08.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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20
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Tian X, Wang X, Li Y. Myosin XI-B is involved in the transport of vesicles and organelles in pollen tubes of Arabidopsis thaliana. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 108:1145-1161. [PMID: 34559914 DOI: 10.1111/tpj.15505] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 09/09/2021] [Accepted: 09/14/2021] [Indexed: 06/13/2023]
Abstract
The movement of organelles and vesicles in pollen tubes depends on F-actin. However, the molecular mechanism through which plant myosin XI drives the movement of organelles is still controversial, and the relationship between myosin XI and vesicle movement in pollen tubes is also unclear. In this study, we found that the siliques of the myosin xi-b/e mutant were obviously shorter than those of the wild-type (WT) and that the seed set of the mutant was severely deficient. The pollen tube growth of myosin xi-b/e was significantly inhibited both in vitro and in vivo. Fluorescence recovery after photobleaching showed that the velocity of vesicle movement in the pollen tube tip of the myosin xi-b/e mutant was lower than that of the WT. It was also found that peroxisome movement was significantly inhibited in the pollen tubes of the myosin xi-b/e mutant, while the velocities of the Golgi stack and mitochondrial movement decreased relatively less in the pollen tubes of the mutant. The endoplasmic reticulum streaming in the pollen tube shanks was not significantly different between the WT and the myosin xi-b/e mutant. In addition, we found that myosin XI-B-GFP colocalized obviously with vesicles and peroxisomes in the pollen tubes of Arabidopsis. Taken together, these results indicate that myosin XI-B may bind mainly to vesicles and peroxisomes, and drive their movement in pollen tubes. These results also suggest that the mechanism by which myosin XI drives organelle movement in plant cells may be evolutionarily conserved compared with other eukaryotic cells.
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Affiliation(s)
- Xiulin Tian
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Xingjuan Wang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Yan Li
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
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21
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Zang J, Kriechbaumer V, Wang P. Plant cytoskeletons and the endoplasmic reticulum network organization. JOURNAL OF PLANT PHYSIOLOGY 2021; 264:153473. [PMID: 34298331 DOI: 10.1016/j.jplph.2021.153473] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 07/07/2021] [Accepted: 07/10/2021] [Indexed: 06/13/2023]
Abstract
Plant endoplasmic reticulum (ER) remodelling is likely to be important for its function in targeted protein secretion, organelle interaction and signal exchange. It has been known for decades that the structure and movement of the ER network is mainly regulated by the actin cytoskeleton through actin motor proteins and membrane-cytoskeleton adaptors. Recent discoveries also revealed alternative pathways that influence ER movement, through a microtubule-based machinery. Therefore, plants utilize both cytoskeletal components to drive ER dynamics, a process that is likely to be dependent on the cell type and the developmental stages. On the other hand, the ER membrane also has a direct effect towards the organization of the cytoskeletal network and disrupting the tethering factors at the ER-PM interface also rearranges the cytoskeletal structure. However, the influence of the ER network on the cytoskeleton organization has not been studied. In this review, we will provide an overview of the ER-cytoskeleton network in plants, and discuss the most recent discoveries in the field.
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Affiliation(s)
- Jingze Zang
- Key Laboratory of Horticultural Plant Biology (MOE), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, Hubei Province, China
| | - Verena Kriechbaumer
- Plant Cell Biology, Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, OX3 0BP, UK
| | - Pengwei Wang
- Key Laboratory of Horticultural Plant Biology (MOE), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, Hubei Province, China.
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22
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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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23
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Jia Q, Zhang S, Lin Y, Zhang J, Li L, Chen H, Zhang Q. Phospholipase Dδ regulates pollen tube growth by modulating actin cytoskeleton organization in Arabidopsis. PLANT SIGNALING & BEHAVIOR 2021; 16:1915610. [PMID: 33853512 PMCID: PMC8205101 DOI: 10.1080/15592324.2021.1915610] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 04/07/2021] [Accepted: 04/07/2021] [Indexed: 05/19/2023]
Abstract
The actin cytoskeleton plays pivotal roles in pollen tube growth by regulating organelle movement, cytoplasmic streaming, and vesicle trafficking. Previous studies have reported that plasma membrane-localized phospholipase Dδ (PLDδ) binds to cortical microtubules and negatively regulates plant stress tolerance. However, it remains unknown whether or how PLDδ regulates microfilament organization. In this study, we found that loss of PLDδ function led to a significant increase in pollen tube growth, whereas PLDδ overexpression resulted in pollen tube growth inhibition. We also found that wild-type PLDδ, rather than Arg 622-mutated PLDδ, complemented the pldδ phenotype in pollen tubes. In vitro biochemical assays demonstrated that PLDδ binds directly to F-actin, and immunofluorescence assays revealed that PLDδ in pollen tubes influences actin organization. Together, these results suggest that PLDδ participates in the development of pollen tube growth by organizing actin filaments.
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Affiliation(s)
- Qianru Jia
- College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, P.R.China
| | - Shujuan Zhang
- College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, P.R.China
| | - Yaoxi Lin
- College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, P.R.China
| | - Jixiu Zhang
- College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, P.R.China
| | - Li Li
- Institute of Botany, Jiangsu Province and Chinese Academy of Sciences (Nanjing Botanical Garden Mem. Sun Yat-Sen), Nanjing, P.R.China
| | - Huatao Chen
- Institute of Industrial Crops, Jiangsu Academy of Agricultural Sciences, Nanjing, P.R.China
| | - Qun Zhang
- College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, P.R.China
- CONTACT Qun Zhang College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing Weigang Road 1, College of Life Sciences #48, 210095, Nanjing, Jiangsu Province, P.R.China.
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24
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Duckney P, Kroon JT, Dixon MR, Hawkins TJ, Deeks MJ, Hussey PJ. NETWORKED2-subfamily proteins regulate the cortical actin cytoskeleton of growing pollen tubes and polarised pollen tube growth. THE NEW PHYTOLOGIST 2021; 231:152-164. [PMID: 33864269 DOI: 10.1111/nph.17391] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 03/29/2021] [Indexed: 06/12/2023]
Abstract
We have recently characterised NET2A as a pollen-specific actin-binding protein that binds F-actin at the plasma membrane of growing pollen tubes. However, the role of NET2 proteins in pollen development and fertilisation have yet to be elucidated. To further characterise the role of Arabidopsis NET2 proteins in pollen development and fertilisation, we analysed the subcellular localisation of NET2A over the course of pollen grain development and investigated the role of the NET2 family using net2 loss-of-function mutants. We observed NET2A to localise to the F-actin cytoskeleton in developing pollen grains as it underwent striking structural reorganisations at specific stages of development and during germination and pollen tube growth. Furthermore, net2 loss-of-function mutants exhibited striking morphological defects in the early stages of pollen tube growth, arising from frequent changes to pollen tube growth trajectory. We observed defects in the cortical actin cytoskeleton and actin-driven subcellular processes in net2 mutant pollen tubes. We demonstrate that NET2 proteins are essential for normal actin-driven pollen development highlighting an important role for the NET2 family members in regulating pollen tube growth during fertilisation.
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Affiliation(s)
- Patrick Duckney
- Department of Biosciences, Durham University, South Road, Durham, DH1 3LE, UK
| | - Johan T Kroon
- Department of Biosciences, Durham University, South Road, Durham, DH1 3LE, UK
| | - Martin R Dixon
- Department of Biosciences, Durham University, South Road, Durham, DH1 3LE, UK
| | - Timothy J Hawkins
- Department of Biosciences, Durham University, South Road, Durham, DH1 3LE, UK
| | - Michael J Deeks
- Department of Biosciences, Durham University, South Road, Durham, DH1 3LE, UK
- College of Life and Environmental Sciences, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
| | - Patrick J Hussey
- Department of Biosciences, Durham University, South Road, Durham, DH1 3LE, UK
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Liu C, Zhang Y, Ren H. Profilin promotes formin-mediated actin filament assembly and vesicle transport during polarity formation in pollen. THE PLANT CELL 2021; 33:1252-1267. [PMID: 33638636 DOI: 10.1093/plcell/koab027] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 01/20/2021] [Indexed: 06/12/2023]
Abstract
Pollen germination is critical for the reproduction of flowering plants. Formin-dependent actin polymerization plays vital roles in vesicle trafficking and polarity establishment during this process. However, how formin-mediated actin assembly is regulated in vivo remains poorly understood. Here, we investigated the function of reproductive profilin 4 and 5 (PRF4 and PRF5) in polarity establishment during pollen germination in Arabidopsis thaliana. Our data showed that the actin filament content was reduced in the prf4 prf5 double mutant and substantially increased in both PRF4- and PRF5-overexpressing pollen grains. By contrast, the positive effect of profilin in promoting actin polymerization was abolished in a formin mutant, atfh5. In addition, the interaction between Arabidopsis formin homology 5 (AtFH5) and actin filaments was attenuated and the trafficking of AtFH5-labeled vesicles was slowed in prf4 prf5 pollen grains. Formation of the collar-like structure at the germination pore was also defective in prf4 prf5 pollen grains as the fast assembly of actin filaments was impaired. Together, our results suggest that PRF4 and PRF5 regulate vesicle trafficking and polarity establishment during pollen germination by promoting AtFH5-mediated actin polymerization and enhancing the interaction between AtFH5 and actin filaments.
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Affiliation(s)
- Chang Liu
- Center for Biological Science and Technology, Institute of Natural Science, Beijing Normal University, Zhuhai 519087, China
| | - Yi Zhang
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education, College of Life Science, Beijing Normal University, Beijing 100875, China
| | - Haiyun Ren
- Center for Biological Science and Technology, Institute of Natural Science, Beijing Normal University, Zhuhai 519087, China
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education, College of Life Science, Beijing Normal University, Beijing 100875, China
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26
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Zhang L, Ma M, Cui L, Liu L. Deciphering the dynamic gene expression patterns of pollen abortion in a male sterile line of Avena sativa through transcriptome analysis at different developmental stages. BMC PLANT BIOLOGY 2021; 21:101. [PMID: 33602130 PMCID: PMC7893748 DOI: 10.1186/s12870-021-02881-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 02/08/2021] [Indexed: 05/14/2023]
Abstract
BACKGROUND Male sterility (MS) has important applications in hybrid seed production, and the abortion of anthers has been observed in many plant species. While most studies have focused on the genetic factors affecting male sterility, the dynamic gene expression patterns of pollen abortion in male sterile lines have not been fully elucidated. In addition, there is still no hybrid oat that is commercially planted due to the lack of a suitable system of male sterility for hybrid breeding. RESULTS In this study, we cultivated a male sterile oat line and a near-isogenic line by crossbreeding to elucidate the expression patterns of genes that may be involved in sterility. The first reported CA male sterile (CAMS) oat line was used for cross-testing and hybridization experiments and was confirmed to exhibit a type of nuclear sterility controlled by recessive genes. Oat stamens of two lines were sampled at four different developmental stages separately. Paired-end RNA sequencing was performed for each sample and generated 252.84 Gb sequences. There were 295,462 unigenes annotated in public databases in all samples, and we compared the histological characteristics and transcriptomes of oat stamens from the two oat lines at different developmental stages. Our results demonstrate that the sterility of the male sterile oat line occurs in the early stage of stamen development and is primarily attributable to abnormal meiosis and the excessive accumulation of superoxide. CONCLUSIONS To the best of our knowledge, this study is the first to decipher the dynamic expression profiles of pollen abortion CAMS and CA male fertile (CAMF) oat lines, which may represent a valuable resource for further studies attempting to understand pollen abortion and anther development in oats.
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Affiliation(s)
- Lijun Zhang
- Crop Germplasms Resources Research Institute, Shanxi Academy of Agricultural Sciences, Taiyuan, China.
| | - Mingchuan Ma
- Crop Germplasms Resources Research Institute, Shanxi Academy of Agricultural Sciences, Taiyuan, China
| | - Lin Cui
- Crop Germplasms Resources Research Institute, Shanxi Academy of Agricultural Sciences, Taiyuan, China
| | - Longlong Liu
- Crop Germplasms Resources Research Institute, Shanxi Academy of Agricultural Sciences, Taiyuan, China
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27
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Xu Y, Huang S. Control of the Actin Cytoskeleton Within Apical and Subapical Regions of Pollen Tubes. Front Cell Dev Biol 2020; 8:614821. [PMID: 33344460 PMCID: PMC7744591 DOI: 10.3389/fcell.2020.614821] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 11/13/2020] [Indexed: 01/07/2023] Open
Abstract
In flowering plants, sexual reproduction involves a double fertilization event, which is facilitated by the delivery of two non-motile sperm cells to the ovule by the pollen tube. Pollen tube growth occurs exclusively at the tip and is extremely rapid. It strictly depends on an intact actin cytoskeleton, and is therefore an excellent model for uncovering the molecular mechanisms underlying dynamic actin cytoskeleton remodeling. There has been a long-term debate about the organization and dynamics of actin filaments within the apical and subapical regions of pollen tube tips. By combining state-of-the-art live-cell imaging with the usage of mutants which lack different actin-binding proteins, our understanding of the origin, spatial organization, dynamics and regulation of actin filaments within the pollen tube tip has greatly improved. In this review article, we will summarize the progress made in this area.
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Affiliation(s)
| | - Shanjin Huang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
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28
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Zhou Y, Yang Y, Niu Y, Fan T, Qian D, Luo C, Shi Y, Li S, An L, Xiang Y. The Tip-Localized Phosphatidylserine Established by Arabidopsis ALA3 Is Crucial for Rab GTPase-Mediated Vesicle Trafficking and Pollen Tube Growth. THE PLANT CELL 2020; 32:3170-3187. [PMID: 32817253 PMCID: PMC7534478 DOI: 10.1105/tpc.19.00844] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 07/17/2020] [Accepted: 08/17/2020] [Indexed: 05/20/2023]
Abstract
RabA4 subfamily proteins, the key regulators of intracellular transport, are vital for tip growth of plant polar cells, but their unique distribution in the apical zone and role in vesicle targeting and trafficking in the tips remain poorly understood. Here, we found that loss of Arabidopsis (Arabidopsis thaliana) AMINOPHOSPHOLIPID ATPASE 3 (ALA3) function resulted in a marked decrease in YFP-RabA4b/ RFP-RabA4d- and FM4-64-labeled vesicles from the inverted-cone zone of the pollen tube tip, misdistribution of certain intramembrane compartment markers, and an obvious increase in pollen tube width. Additionally, we revealed that phosphatidylserine (PS) was abundant in the inverted-cone zone of the apical pollen tube in wild-type Arabidopsis and was mainly colocalized with the trans-Golgi network/early endosome, certain post-Golgi compartments, and the plasma membrane. Loss of ALA3 function resulted in loss of polar localization of apical PS and significantly decreased PS distribution, suggesting that ALA3 is a key regulator for establishing and maintaining the polar localization of apical PS in pollen tubes. We further demonstrated that certain Rab GTPases colocalized with PS in vivo and bound to PS in vitro. Moreover, ALA3 and RabA4d collectively regulated pollen tube growth genetically. Thus, we propose that the tip-localized PS established by ALA3 is crucial for Rab GTPase-mediated vesicle targeting/trafficking and polar growth of pollen tubes in Arabidopsis.
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Affiliation(s)
- Yuelong Zhou
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Yang Yang
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Yue Niu
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - TingTing Fan
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Dong Qian
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Changxin Luo
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Yumei Shi
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Shanwei Li
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an 271018, China
| | - Lizhe An
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Yun Xiang
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
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29
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Haque T, Eaves DJ, Lin Z, Zampronio CG, Cooper HJ, Bosch M, Smirnoff N, Franklin-Tong VE. Self-Incompatibility Triggers Irreversible Oxidative Modification of Proteins in Incompatible Pollen. PLANT PHYSIOLOGY 2020; 183:1391-1404. [PMID: 32321844 PMCID: PMC7333688 DOI: 10.1104/pp.20.00066] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 04/07/2020] [Indexed: 06/08/2023]
Abstract
Self-incompatibility (SI) is used by many angiosperms to prevent self-fertilization and inbreeding. In common poppy (Papaver rhoeas), interaction of cognate pollen and pistil S-determinants triggers programmed cell death (PCD) of incompatible pollen. We previously identified that reactive oxygen species (ROS) signal to SI-PCD. ROS-induced oxidative posttranslational modifications (oxPTMs) can regulate protein structure and function. Here, we have identified and mapped oxPTMs triggered by SI in incompatible pollen. Notably, SI-induced pollen had numerous irreversible oxidative modifications, while untreated pollen had virtually none. Our data provide a valuable analysis of the protein targets of ROS in the context of SI-induction and comprise a benchmark because currently there are few reports of irreversible oxPTMs in plants. Strikingly, cytoskeletal proteins and enzymes involved in energy metabolism are a prominent target of ROS. Oxidative modifications to a phosphomimic form of a pyrophosphatase result in a reduction of its activity. Therefore, our results demonstrate irreversible oxidation of pollen proteins during SI and provide evidence that this modification can affect protein function. We suggest that this reduction in cellular activity could lead to PCD.
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Affiliation(s)
- Tamanna Haque
- School of Biosciences, College of Life and Environmental Sciences, School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Deborah J Eaves
- School of Biosciences, College of Life and Environmental Sciences, School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Zongcheng Lin
- School of Biosciences, College of Life and Environmental Sciences, School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Cleidiane G Zampronio
- School of Biosciences, College of Life and Environmental Sciences, School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Helen J Cooper
- School of Biosciences, College of Life and Environmental Sciences, School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Maurice Bosch
- Institute of Biological, Environmental and Rural Sciences (IBERS), Aberystwyth University, Gogerddan, Aberystwyth SY23 3EB, United Kingdom
| | - Nicholas Smirnoff
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, United Kingdom
| | - Vernonica E Franklin-Tong
- School of Biosciences, College of Life and Environmental Sciences, School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
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30
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Zhao W, Qu X, Zhuang Y, Wang L, Bosch M, Franklin-Tong VE, Xue Y, Huang S. Villin controls the formation and enlargement of punctate actin foci in pollen tubes. J Cell Sci 2020; 133:jcs237404. [PMID: 32051284 DOI: 10.1242/jcs.237404] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 02/01/2020] [Indexed: 11/20/2022] Open
Abstract
Self-incompatibility (SI) in the poppy Papaver rhoeas triggers dramatic alterations in actin within pollen tubes. However, how these actin alterations are mechanistically achieved remains largely unexplored. Here, we used treatment with the Ca2+ ionophore A23187 to mimic the SI-induced elevation in cytosolic Ca2+ and trigger formation of the distinctive F-actin foci. Live-cell imaging revealed that this remodeling involves F-actin fragmentation and depolymerization, accompanied by the rapid formation of punctate actin foci and subsequent increase in their size. We established that actin foci are generated and enlarged from crosslinking of fragmented actin filament structures. Moreover, we show that villins associate with actin structures and are involved in this actin reorganization process. Notably, we demonstrate that Arabidopsis VILLIN5 promotes actin depolymerization and formation of actin foci by fragmenting actin filaments, and controlling the enlargement of actin foci via bundling of actin filaments. Our study thus uncovers important novel insights about the molecular players and mechanisms involved in forming the distinctive actin foci in pollen tubes.
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Affiliation(s)
- Wanying Zhao
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Xiaolu Qu
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan 430070, China
| | - Yuhui Zhuang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Ludi Wang
- Institute of Biological, Environmental and Rural Sciences (IBERS), Aberystwyth University, Plas Gogerddan, Aberystwyth, SY23 3EE, UK
| | - Maurice Bosch
- Institute of Biological, Environmental and Rural Sciences (IBERS), Aberystwyth University, Plas Gogerddan, Aberystwyth, SY23 3EE, UK
| | - Vernonica E Franklin-Tong
- School of Biosciences, College of Life and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - 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
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31
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Qu X, Wang Q, Wang H, Huang S. Visualization of Actin Organization and Quantification in Fixed Arabidopsis Pollen Grains and Tubes. Bio Protoc 2020; 10:e3509. [PMID: 33654717 DOI: 10.21769/bioprotoc.3509] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 12/10/2019] [Accepted: 12/31/2019] [Indexed: 11/02/2022] Open
Abstract
Although it is widely accepted that actin plays an important role in regulating pollen germination and pollen tube growth, how actin exactly performs functions remains incompletely understood. As the function of actin is dictated by its spatial organization, it is the key to reveal how exactly actin distributes in space in pollen cells. Here we describe the protocol of revealing and quantifying the spatial organization of actin using fluorescent phalloidin-staining in fixed Arabidopsis pollen grains and pollen tubes. We also introduce the method of assessing the stability and/or turnover rate of actin filaments in pollen cells using the treatment of latrunculin B.
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Affiliation(s)
- Xiaolu Qu
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, China
| | - Qiannan Wang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Haiyan Wang
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, China
| | - Shanjin Huang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
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32
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Diao M, Li X, Huang S. Arabidopsis AIP1-1 regulates the organization of apical actin filaments by promoting their turnover in pollen tubes. SCIENCE CHINA-LIFE SCIENCES 2019; 63:239-250. [PMID: 31240522 DOI: 10.1007/s11427-019-9532-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 04/02/2019] [Indexed: 11/24/2022]
Abstract
Apical actin filaments are highly dynamic structures that are crucial for rapid pollen tube growth, but the mechanisms regulating their dynamics and spatial organization remain incompletely understood. We here identify that AtAIP1-1 is important for regulating the turnover and organization of apical actin filaments in pollen tubes. AtAIP1-1 is distributed uniformly in the pollen tube and loss of function of AtAIP1-1 affects the organization of the actin cytoskeleton in the pollen tube. Specifically, actin filaments became disorganized within the apical region of aip1-1 pollen tubes. Consistent with the role of apical actin filaments in spatially restricting vesicles in pollen tubes, the apical region occupied by vesicles becomes enlarged in aip1-1 pollen tubes compared to WT. Using ADF1 as a representative actin-depolymerizing factor, we demonstrate that AtAIP1-1 enhances ADF1-mediated actin depolymerization and filament severing in vitro, although AtAIP1-1 alone does not have an obvious effect on actin assembly and disassembly. The dynamics of apical actin filaments are reduced in aip1-1 pollen tubes compared to WT. Our study suggests that AtAIP1-1 works together with ADF to act as a module in regulating the dynamics of apical actin filaments to facilitate the construction of the unique "apical actin structure" in the pollen tube.
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Affiliation(s)
- Min Diao
- Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
- iHuman Institute, Shanghai Tech University, Shanghai, 201210, China
| | - Xin Li
- Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Shanjin Huang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China.
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33
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Parrotta L, Faleri C, Guerriero G, Cai G. Cold stress affects cell wall deposition and growth pattern in tobacco pollen tubes. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2019; 283:329-342. [PMID: 31128704 DOI: 10.1016/j.plantsci.2019.03.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 01/29/2019] [Accepted: 03/15/2019] [Indexed: 05/08/2023]
Abstract
Cold is an abiotic stress seriously threatening crop productivity by decreasing biomass production. The pollen tube is a target of cold stress, but also a useful model to address questions on cell wall biosynthesis. We here provide (immuno)cytological data relative to the impact of cold on the pollen tube cell wall. We clearly show that the growth pattern is severely affected by the stress, since the typical pulsed-growth mechanism accompanied by the periodic deposition of pectin rings is absent/severely reduced. Additionally, pectins and cellulose accumulate in bulges provoked by the stress, while callose, which colocalizes with pectins in the periodic rings formed during pulsed growth, accumulates randomly in the stressed samples. The altered distribution of the cell wall components is accompanied by differences in the localization of glucan synthases: cellulose synthase shows a more diffuse localization, while callose synthase shows a more frequent cytoplasmic accumulation, thereby denoting a failure in plasma membrane insertion. The cell wall observations are complemented by the analysis of intracellular Ca2+, pH and reactive oxygen species (ROS): while in the case of pH no major differences are observed, a less focused Ca2+ and ROS gradients are present in the stressed samples. The standard oscillatory growth of pollen tubes is recovered by transient changes of turgor pressure induced by hypoosmotic media. Overall our data contribute to the understanding of the impact that cold stress has on the normal development of the pollen tube and unveil the cell wall-related aberrant features accompanying the observed alterations.
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Affiliation(s)
- Luigi Parrotta
- Università di Bologna, Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Via Irnerio 42, Bologna, Italy
| | - Claudia Faleri
- Università di Siena, Dipartimento di Scienze della Vita, via P.A. Mattioli 4, Siena, Italy
| | - Gea Guerriero
- Research and Innovation Department, Luxembourg Institute of Science and Technology, 5 avenue des Hauts-Fourneaux, L-4362, Esch/Alzette, Luxembourg
| | - Giampiero Cai
- Università di Siena, Dipartimento di Scienze della Vita, via P.A. Mattioli 4, Siena, Italy.
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34
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Mechanism of CAP1-mediated apical actin polymerization in pollen tubes. Proc Natl Acad Sci U S A 2019; 116:12084-12093. [PMID: 31123151 DOI: 10.1073/pnas.1821639116] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Srv2p/CAP1 is an essential regulator of actin turnover, but its exact function in regulating actin polymerization, particularly the contribution of its actin nucleotide exchange activity, remains incompletely understood. We found that, although Arabidopsis CAP1 is distributed uniformly in the cytoplasm, its loss of function has differential effects on the actin cytoskeleton within different regions of the pollen tube. Specifically, the F-actin level increases in the shank but decreases in the apical region of cap1 pollen tubes. The reduction in apical F-actin results mainly from impaired polymerization of membrane-originated actin within cap1 pollen tubes. The actin nucleotide exchange activity of CAP1 is involved in apical actin polymerization. CAP1 acts synergistically with pollen ADF and profilin to promote actin turnover in vitro, and it can overcome the inhibitory effects of ADF and synergize with profilin to promote actin nucleotide exchange. Consistent with its role as a shuttle molecule between ADF and profilin, the cytosolic concentration of CAP1 is much lower than that of ADF and profilin in pollen. Thus, CAP1 synergizes with ADF and profilin to drive actin turnover in pollen and promote apical actin polymerization in pollen tubes in a manner that involves its actin nucleotide exchange activity.
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35
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Laggoun F, Dardelle F, Dehors J, Falconet D, Driouich A, Rochais C, Dallemagne P, Lehner A, Mollet JC. A chemical screen identifies two novel small compounds that alter Arabidopsis thaliana pollen tube growth. BMC PLANT BIOLOGY 2019; 19:152. [PMID: 31010418 PMCID: PMC6475968 DOI: 10.1186/s12870-019-1743-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 03/27/2019] [Indexed: 05/23/2023]
Abstract
BACKGROUND During sexual reproduction, pollen grains land on the stigma, rehydrate and produce pollen tubes that grow through the female transmitting-tract tissue allowing the delivery of the two sperm cells to the ovule and the production of healthy seeds. Because pollen tubes are single cells that expand by tip-polarized growth, they represent a good model to study the growth dynamics, cell wall deposition and intracellular machineries. Aiming to understand this complex machinery, we used a low throughput chemical screen approach in order to isolate new tip-growth disruptors. The effect of a chemical inhibitor of monogalactosyldiacylglycerol synthases, galvestine-1, was also investigated. The present work further characterizes their effects on the tip-growth and intracellular dynamics of pollen tubes. RESULTS Two small compounds among 258 were isolated based on their abilities to perturb pollen tube growth. They were found to disrupt in vitro pollen tube growth of tobacco, tomato and Arabidopsis thaliana. We show that these 3 compounds induced abnormal phenotypes (bulging and/or enlarged pollen tubes) and reduced pollen tube length in a dose dependent manner. Pollen germination was significantly reduced after treatment with the two compounds isolated from the screen. They also affected cell wall material deposition in pollen tubes. The compounds decreased anion superoxide accumulation, disorganized actin filaments and RIC4 dynamics suggesting that they may affect vesicular trafficking at the pollen tube tip. CONCLUSION These molecules may alter directly or indirectly ROP1 activity, a key regulator of pollen tube growth and vesicular trafficking and therefore represent good tools to further study cellular dynamics during polarized-cell growth.
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Affiliation(s)
- Ferdousse Laggoun
- Normandie Université, UNIROUEN, Laboratoire Glycobiologie et Matrice Extracellulaire Végétale EA4358, Fédération de Recherche “NORVEGE”- FED 4277, 76000 Rouen, France
| | - Flavien Dardelle
- Normandie Université, UNIROUEN, Laboratoire Glycobiologie et Matrice Extracellulaire Végétale EA4358, Fédération de Recherche “NORVEGE”- FED 4277, 76000 Rouen, France
- Present Address: LPS-BioSciences, Bâtiment 409, Université Paris-Sud, 91400 Orsay, France
| | - Jérémy Dehors
- Normandie Université, UNIROUEN, Laboratoire Glycobiologie et Matrice Extracellulaire Végétale EA4358, Fédération de Recherche “NORVEGE”- FED 4277, 76000 Rouen, France
| | - Denis Falconet
- Laboratoire de Physiologie Cellulaire et Végétale, CNRS, CEA, INRA, Université Grenoble Alpes, Institut de Biosciences et Biotechnologies de Grenoble, CEA Grenoble, 38000 Grenoble, cedex 9 France
| | - Azeddine Driouich
- Normandie Université, UNIROUEN, Laboratoire Glycobiologie et Matrice Extracellulaire Végétale EA4358, Fédération de Recherche “NORVEGE”- FED 4277, 76000 Rouen, France
| | - Christophe Rochais
- Normandie Université, UNICAEN, Centre d’Etudes et de Recherche sur le Médicament de Normandie, CNRS 3038 INC3M, SFR ICORE, 14032, Caen, France
| | - Patrick Dallemagne
- Normandie Université, UNICAEN, Centre d’Etudes et de Recherche sur le Médicament de Normandie, CNRS 3038 INC3M, SFR ICORE, 14032, Caen, France
| | - Arnaud Lehner
- Normandie Université, UNIROUEN, Laboratoire Glycobiologie et Matrice Extracellulaire Végétale EA4358, Fédération de Recherche “NORVEGE”- FED 4277, 76000 Rouen, France
| | - Jean-Claude Mollet
- Normandie Université, UNIROUEN, Laboratoire Glycobiologie et Matrice Extracellulaire Végétale EA4358, Fédération de Recherche “NORVEGE”- FED 4277, 76000 Rouen, France
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Wang L, Lin Z, Triviño M, Nowack MK, Franklin-Tong VE, Bosch M. Self-incompatibility in Papaver pollen: programmed cell death in an acidic environment. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:2113-2123. [PMID: 30481323 PMCID: PMC7116307 DOI: 10.1093/jxb/ery406] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Accepted: 11/07/2018] [Indexed: 05/18/2023]
Abstract
Self-incompatibility (SI) is a genetically controlled mechanism that prevents self-fertilization and thus encourages outbreeding and genetic diversity. During pollination, most SI systems utilize cell-cell recognition to reject incompatible pollen. Mechanistically, one of the best-studied SI systems is that of Papaver rhoeas (poppy), which involves the interaction between the two S-determinants, a stigma-expressed secreted protein (PrsS) and a pollen-expressed plasma membrane-localized protein (PrpS). This interaction is the critical step in determining acceptance of compatible pollen or rejection of incompatible pollen. Cognate PrpS-PrsS interaction triggers a signalling network causing rapid growth arrest and eventually programmed cell death (PCD) in incompatible pollen. In this review, we provide an overview of recent advances in our understanding of the major components involved in the SI-induced PCD (SI-PCD). In particular, we focus on the importance of SI-induced intracellular acidification and consequences for protein function, and the regulation of soluble inorganic pyrophosphatase (Pr-p26.1) activity by post-translational modification. We also discuss attempts to identify protease(s) involved in the SI-PCD process. Finally, we outline future opportunities made possible by the functional transfer of the P. rhoeas SI system to Arabidopsis.
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Affiliation(s)
- Ludi Wang
- Institute of Biological, Environmental and Rural Sciences (IBERS), Aberystwyth University, Plas Gogerddan, Aberystwyth, UK
| | - Zongcheng Lin
- Department of Plant Biotechnology and Genetics, Ghent University, Ghent, Belgium
- VIB Center for Plant Systems Biology, Ghent, Belgium
| | - Marina Triviño
- Institute of Biological, Environmental and Rural Sciences (IBERS), Aberystwyth University, Plas Gogerddan, Aberystwyth, UK
- Department of Plant Biotechnology and Genetics, Ghent University, Ghent, Belgium
- VIB Center for Plant Systems Biology, Ghent, Belgium
| | - Moritz K Nowack
- Department of Plant Biotechnology and Genetics, Ghent University, Ghent, Belgium
- VIB Center for Plant Systems Biology, Ghent, Belgium
| | - Vernonica E Franklin-Tong
- School of Biosciences, College of Life and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, UK
| | - Maurice Bosch
- Institute of Biological, Environmental and Rural Sciences (IBERS), Aberystwyth University, Plas Gogerddan, Aberystwyth, UK
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Filipin EP, Pereira DT, Ouriques LC, Bouzon ZL, Simioni C. Participation of actin filaments, myosin and phosphatidylinositol 3-kinase in the formation and polarisation of tetraspore germ tube of Gelidium floridanum (Rhodophyta, Florideophyceae). PLANT BIOLOGY (STUTTGART, GERMANY) 2019; 21:352-360. [PMID: 30472775 DOI: 10.1111/plb.12946] [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: 10/03/2018] [Accepted: 11/21/2018] [Indexed: 06/09/2023]
Abstract
This study aimed to examine the evidence of direct interaction among actin, myosin and phosphatidylinositol 3-kinase (PI3K) in the polarisation and formation of the tetraspore germ tube of Gelidium floridanum. After release, tetraspores were exposed to cytochalasin B, latrunculin B, LY294002 and BDM for a period of 6 h. In control samples, formation of the germ tube occurred after the experimental period, with cellulose formation and elongated chloroplasts moving through the tube region in the presence of F-actin. In the presence of cytochalasin B, an inhibitor of F-actin, latrunculin B, an inhibitor of G-actin, and BDM, a myosin inhibitor, tetraspores showed no formation of the germ tube or cellulose. Spherical-shaped chloroplasts were observed in the central region with a few F-actin filaments in the periphery of the cytoplasm. Tetraspores treated with LY294002, a PI3K inhibitor, showed no formation of the tube at the highest concentrations. Polarisation of cytoplasmic contents did not occur, only cellulose formation. It was concluded that F-actin directs the cell wall components and contributes to the maintenance of chloroplast shape and elongation during germ tube formation. PI3K plays a fundamental role in signalling for the asymmetric polarisation of F-actin. Thus, F-actin regulates the polarisation and germination processes of tetraspores of G. floridanum.
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Affiliation(s)
- E P Filipin
- Plant Cell Biology Laboratory, Department of Cell Biology, Embryology and Genetics, Federal University of Santa Catarina, Florianópolis, SC, Brazil
| | - D T Pereira
- Plant Cell Biology Laboratory, Department of Cell Biology, Embryology and Genetics, Federal University of Santa Catarina, Florianópolis, SC, Brazil
| | - L C Ouriques
- Central Laboratory of Electron Microscopy, Federal University of Santa Catarina, Florianópolis, SC, Brazil
| | - Z L Bouzon
- Central Laboratory of Electron Microscopy, Federal University of Santa Catarina, Florianópolis, SC, Brazil
| | - C Simioni
- Postdoctoral Research of Postgraduate Program in Cell Biology and Development, Department of Cell Biology, Embryology and Genetics, Federal University of Santa Catarina, Florianópolis, SC, Brazil
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Bascom C, Burkart GM, Mallett DR, O’Sullivan JE, Tomaszewski AJ, Walsh K, Bezanilla M. Systematic survey of the function of ROP regulators and effectors during tip growth in the moss Physcomitrella patens. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:447-457. [PMID: 30380098 PMCID: PMC6322563 DOI: 10.1093/jxb/ery376] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Accepted: 10/18/2018] [Indexed: 05/03/2023]
Abstract
Rho/Rac of plants (ROP) GTPases are plant-specific small GTPases that regulate cell morphology. ROP activity is controlled by several families of regulatory proteins. However, how these diverse regulators contribute to polarized growth remains understudied. In a system-wide approach, we used RNAi to silence each gene family of known ROP regulators in the juvenile tissues of the moss Physcomitrella patens. We found that the GTPase activating proteins, but not the ROP enhancers, are essential for tip growth. The guanine exchange factors (GEFs), which are comprised of ROPGEFs and Spikes, both contribute to growth. However, silencing Spikes results in less-polarized plants as compared to silencing ROPGEFs, suggesting that Spikes contribute more to establishing cell polarity. Silencing the single-gene family of guanine dissociation inhibitors also inhibits growth, resulting in small, unpolarized plants. In contrast, silencing the ROP effector ROP-interactive CRIB-containing (RIC) protein, which is encoded by a single gene, results in plants larger than the controls, suggesting that RIC functions to inhibit tip growth in moss. Taken together, this systematic loss-of-function survey provides insights into the function of ROP regulators during polarized growth.
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Affiliation(s)
- Carlisle Bascom
- Plant Biology Graduate Program, University of Massachusetts, Amherst, USA
- Department of Biological Sciences, Dartmouth College, Hanover NH, USA
| | - Graham M Burkart
- Plant Biology Graduate Program, University of Massachusetts, Amherst, USA
| | - Darren R Mallett
- Department of Biological Sciences, Dartmouth College, Hanover NH, USA
- Biology Department, University of Massachusetts, Amherst, USA
| | | | | | - Katherine Walsh
- Biology Department, University of Massachusetts, Amherst, USA
| | - Magdalena Bezanilla
- Department of Biological Sciences, Dartmouth College, Hanover NH, USA
- Correspondence:
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Ahmad R. Steroidal glycoalkaloids from Solanum nigrum target cytoskeletal proteins: an in silico analysis. PeerJ 2019; 7:e6012. [PMID: 30627484 PMCID: PMC6321755 DOI: 10.7717/peerj.6012] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 10/26/2018] [Indexed: 12/03/2022] Open
Abstract
Background Solanum nigrum (black nightshade; S. nigrum), a member of family Solanaceae, has been endowed with a heterogeneous array of secondary metabolites of which the steroidal glycoalkaloids (SGAs) and steroidal saponins (SS) have vast potential to serve as anticancer agents. Since there has been much controversy regarding safety of use of glycoalkaloids as anticancer agents, this area has remained more or less unexplored. Cytoskeletal proteins like actin play an important role in maintaining cell shape, synchronizing cell division, cell motility, etc. and along with their accessory proteins may also serve as important therapeutic targets for potential anticancer candidates. In the present study, glycoalkaloids and saponins from S. nigrum were screened for their interaction and binding affinity to cytoskeletal proteins, using molecular docking. Methods Bioactivity score and Prediction of Activity Spectra for Substances (PASS) analysis were performed using softwares Molinspiration and Osiris Data Explorer respectively, to assess the feasibility of selected phytoconstituents as potential drug candidates. The results were compared with two standard reference drugs doxorubicin hydrochloride (anticancer) and tetracycline (antibiotic). Multivariate data obtained were analyzed using principal component analysis (PCA). Results Docking analysis revealed that the binding affinities of the phytoconstituents towards the target cytoskeletal proteins decreased in the order coronin>villin>ezrin>vimentin>gelsolin>thymosin>cofilin. Glycoalkaloid solasonine displayed the greatest binding affinity towards the target proteins followed by alpha-solanine whereas amongst the saponins, nigrumnin-I showed maximum binding affinity. PASS Analysis of the selected phytoconstituents revealed 1 to 3 violations of Lipinski’s parameters indicating the need for modification of their structure-activity relationship (SAR) for improvement of their bioactivity and bioavailability. Glycoalkaloids and saponins all had bioactivity scores between −5.0 and 0.0 with respect to various receptor proteins and target enzymes. Solanidine, solasodine and solamargine had positive values of druglikeness which indicated that these compounds have the potential for development into future anticancer drugs. Toxicity potential evaluation revealed that glycoalkaloids and saponins had no toxicity, tumorigenicity or irritant effect(s). SAR analysis revealed that the number, type and location of sugar or the substitution of hydroxyl group on alkaloid backbone had an effect on the activity and that the presence of α-L-rhamnopyranose sugar at C-2 was critical for a compound to exhibit anticancer activity. Conclusion The present study revealed some cytoskeletal target(s) for S. nigrum phytoconstituents by docking analysis that have not been previously reported and thus warrant further investigations both in vitro and in vivo.
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Affiliation(s)
- Rumana Ahmad
- Department of Biochemisty, Era's Lucknow Medical College and Hospital, Era University, Lucknow, Uttar Pradesh, India
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Sengupta S, Mangu V, Sanchez L, Bedre R, Joshi R, Rajasekaran K, Baisakh N. An actin-depolymerizing factor from the halophyte smooth cordgrass, Spartina alterniflora (SaADF2), is superior to its rice homolog (OsADF2) in conferring drought and salt tolerance when constitutively overexpressed in rice. PLANT BIOTECHNOLOGY JOURNAL 2019; 17:188-205. [PMID: 29851294 PMCID: PMC6330539 DOI: 10.1111/pbi.12957] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Revised: 05/18/2018] [Accepted: 05/25/2018] [Indexed: 05/20/2023]
Abstract
Actin-depolymerizing factors (ADFs) maintain the cellular actin network dynamics by regulating severing and disassembly of actin filaments in response to environmental cues. An ADF isolated from a monocot halophyte, Spartina alterniflora (SaADF2), imparted significantly higher level of drought and salinity tolerance when expressed in rice than its rice homologue OsADF2. SaADF2 differs from OsADF2 by a few amino acid residues, including a substitution in the regulatory phosphorylation site serine-6, which accounted for its weak interaction with OsCDPK6 (calcium-dependent protein kinase), thus resulting in an increased efficacy of SaADF2 and enhanced cellular actin dynamics. SaADF2 overexpression preserved the actin filament organization better in rice protoplasts under desiccation stress. The predicted tertiary structure of SaADF2 showed a longer F-loop than OsADF2 that could have contributed to higher actin-binding affinity and rapid F-actin depolymerization in vitro by SaADF2. Rice transgenics constitutively overexpressing SaADF2 (SaADF2-OE) showed better growth, relative water content, and photosynthetic and agronomic yield under drought conditions than wild-type (WT) and OsADF2 overexpressers (OsADF2-OE). SaADF2-OE preserved intact grana structure after prolonged drought stress, whereas WT and OsADF2-OE presented highly damaged and disorganized grana stacking. The possible role of ADF2 in transactivation was hypothesized from the comparative transcriptome analyses, which showed significant differential expression of stress-related genes including interacting partners of ADF2 in overexpressers. Identification of a complex, differential interactome decorating or regulating stress-modulated cytoskeleton driven by ADF isoforms will lead us to key pathways that could be potential target for genome engineering to improve abiotic stress tolerance in agricultural crops.
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Affiliation(s)
- Sonali Sengupta
- School of PlantEnvironmental and Soil SciencesLouisiana State University Agricultural CenterBaton RougeLAUSA
| | - Venkata Mangu
- School of PlantEnvironmental and Soil SciencesLouisiana State University Agricultural CenterBaton RougeLAUSA
- Present address:
Department of BiochemistrySchool of Dental MedicineUniversity of PennsylvaniaPhiladelphiaPAUSA
| | - Luis Sanchez
- School of PlantEnvironmental and Soil SciencesLouisiana State University Agricultural CenterBaton RougeLAUSA
- Present address:
Escuela Superior Politécnica del LitoralCentro de Investigaciones Biotecnológicas del EcuadorGuayaquilEcuador
| | - Renesh Bedre
- School of PlantEnvironmental and Soil SciencesLouisiana State University Agricultural CenterBaton RougeLAUSA
- Present address:
Texas A&M AgriLife Research and Extension CenterWeslacoTXUSA
| | - Rohit Joshi
- School of PlantEnvironmental and Soil SciencesLouisiana State University Agricultural CenterBaton RougeLAUSA
- Present address:
School of Life SciencesJawaharlal Nehru UniversityNew DelhiIndia
| | | | - Niranjan Baisakh
- School of PlantEnvironmental and Soil SciencesLouisiana State University Agricultural CenterBaton RougeLAUSA
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Zhang S, Wang C, Xie M, Liu J, Kong Z, Su H. Actin Bundles in The Pollen Tube. Int J Mol Sci 2018; 19:ijms19123710. [PMID: 30469514 PMCID: PMC6321563 DOI: 10.3390/ijms19123710] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Revised: 11/18/2018] [Accepted: 11/19/2018] [Indexed: 12/31/2022] Open
Abstract
The angiosperm pollen tube delivers two sperm cells into the embryo sac through a unique growth strategy, named tip growth, to accomplish fertilization. A great deal of experiments have demonstrated that actin bundles play a pivotal role in pollen tube tip growth. There are two distinct actin bundle populations in pollen tubes: the long, rather thick actin bundles in the shank and the short, highly dynamic bundles near the apex. With the development of imaging techniques over the last decade, great breakthroughs have been made in understanding the function of actin bundles in pollen tubes, especially short subapical actin bundles. Here, we tried to draw an overall picture of the architecture, functions and underlying regulation mechanism of actin bundles in plant pollen tubes.
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Affiliation(s)
- Shujuan Zhang
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education College of Life Science, Northwest University, Xi'an 710069, China.
| | - Chunbo Wang
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education College of Life Science, Northwest University, Xi'an 710069, China.
| | - Min Xie
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education College of Life Science, Northwest University, Xi'an 710069, China.
| | - Jinyu Liu
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education College of Life Science, Northwest University, Xi'an 710069, China.
| | - Zhe Kong
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education College of Life Science, Northwest University, Xi'an 710069, China.
| | - Hui Su
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education College of Life Science, Northwest University, Xi'an 710069, China.
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Arabidopsis class I formins control membrane-originated actin polymerization at pollen tube tips. PLoS Genet 2018; 14:e1007789. [PMID: 30418966 PMCID: PMC6258422 DOI: 10.1371/journal.pgen.1007789] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 11/26/2018] [Accepted: 10/25/2018] [Indexed: 12/17/2022] Open
Abstract
A population of dynamic apical actin filaments is required for rapid polarized pollen tube growth. However, the cellular mechanisms driving their assembly remain incompletely understood. It was postulated that formin is a major player in nucleating apical actin assembly, but direct genetic and cytological evidence remains to be firmly established. Here we found that both Arabidopsis formin 3 (AtFH3) and formin 5 (AtFH5) are involved in the regulation of apical actin polymerization and actin array construction in pollen tubes, with AtFH3 playing a more dominant role. We found that both formins have plasma membrane (PM) localization signals but exhibit distinct PM localization patterns in the pollen tube, and loss of their function reduces the amount of apical actin filaments. Live-cell imaging revealed that the reduction in filamentous actin is very likely due to the decrease in filament elongation. Furthermore, we found that the rate of tip-directed vesicle transport is reduced and the pattern of apical vesicle accumulation is altered in formin loss-of-function mutant pollen tubes, which explains to some extent the reduction in pollen tube elongation. Thus, we provide direct genetic and cytological evidence showing that formin is an important player in nucleating actin assembly from the PM at pollen tube tips. Actin polymerization has been implicated in the regulation of rapid polarized pollen tube growth. The important role of actin polymerization is well appreciated, but the mechanisms that regulate rapid actin polymerization in pollen tubes remain incompletely understood. It was postulated that one of the major actin polymerization pathways in pollen tubes involves formin/profilin modules. However, direct genetic and cytological evidence is still required to support the role of formin in this framework. Using state-of-the-art live-cell imaging in combination with reverse genetic approaches, we demonstrate here that two class I formins, Arabidopsis formin 3 (AtFH3) and formin 5 (AtFH5), are involved in the regulation of apical actin polymerization and actin array construction in pollen tubes. In support of the role of AtFH3 and AtFH5 in regulating membrane-originated apical actin polymerization, we found that both of them are localized to the plasma membrane (PM) at pollen tube tips. Live-cell imaging revealed that the reduction in filamentous actin is very likely due to the decrease in elongation of actin filaments originating from the apical membrane. We also found that AtFH3 and AtFH5 exhibit distinct PM localization patterns in the pollen tube, suggesting that they might have distinct roles in regulating actin polymerization in pollen tubes. Our study provides direct genetic and cytological evidence that formins act as important players in regulating apical actin assembly in pollen tubes.
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Liu C, Zhang Y, Ren H. Actin Polymerization Mediated by AtFH5 Directs the Polarity Establishment and Vesicle Trafficking for Pollen Germination in Arabidopsis. MOLECULAR PLANT 2018; 11:1389-1399. [PMID: 30296598 DOI: 10.1016/j.molp.2018.09.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 09/10/2018] [Accepted: 09/27/2018] [Indexed: 05/13/2023]
Abstract
The process of pollen germination is crucial for flowering plant reproduction, but the mechanisms through which pollen grains establish polarity and select germination sites are not well understood. In this study, we report that a formin family protein, AtFH5, is localized to the vesicles and rotates ahead of Lifeact-mEGFP-labeled actin filaments during pollen germination. The translocation of AtFH5 to the plasma membrane initiates the assembly of a collar-like actin structure at the prospective germination site prior to germination. Genetic and pharmacological evidence further revealed an interdependent relationship between the mobility of AtFH5-labeled vesicles and the polymerization of actin filaments: vesicle-localized AtFH5 promotes actin assembly, and the polymerization and elongation of actin filaments, in turn, is essential for the mobility of AtFH5-labeled vesicles in pollen grains. Taken together, our work revealed a molecular mechanism underlying the polarity establishment and vesicle mobility during pollen germination.
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Affiliation(s)
- Chang Liu
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education, College of Life Science, Beijing Normal University, Beijing 100875, China
| | - Yi Zhang
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education, College of Life Science, Beijing Normal University, Beijing 100875, China
| | - Haiyun Ren
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education, College of Life Science, Beijing Normal University, Beijing 100875, China.
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Li J, Chen S, Wang X, Shi C, Liu H, Yang J, Shi W, Guo J, Jia H. Hydrogen Sulfide Disturbs Actin Polymerization via S-Sulfhydration Resulting in Stunted Root Hair Growth. PLANT PHYSIOLOGY 2018; 178:936-949. [PMID: 30166418 PMCID: PMC6181039 DOI: 10.1104/pp.18.00838] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 08/21/2018] [Indexed: 05/20/2023]
Abstract
Hydrogen sulfide (H2S) is an important signaling molecule in plants. Our previous report suggested that H2S signaling affects the actin cytoskeleton and root hair growth. However, the underlying mechanisms of its effects are not understood. S-Sulfhydration of proteins is regulated directly by H2S, which converts the thiol groups of cysteine (Cys) residues to persulfides and alters protein function. In this work, we studied the effects of S-sulfhydration on actin dynamics in Arabidopsis (Arabidopsis thaliana). We generated transgenic plants overexpressing the H2S biosynthesis-related genes l-CYSTEINE DESULFHYDRASE (LCD) and d-CYSTEINE DESULFHYDRASE in the O-acetylserine(thiol)lyase isoform a1 (oasa1) mutant and Columbia-0 backgrounds. The H2S content increased significantly in overexpressing LCD/oasa1 plants. The density of filamentous actin (F-actin) bundles and the F-actin/globular actin ratio decreased in overexpressing LCD/oasa1 plants. S-Sulfhydration also was enhanced in overexpressing LCD/oasa1 plants. An analysis of actin dynamics suggested that S-sulfhydration inhibited actin polymerization. We also found that ACTIN2 (ACT2) was S-sulfhydrated at Cys-287. Cys-287 is adjacent to the D-loop, which acts as a central region for hydrophobic and electrostatic interactions and stabilizes F-actin filaments. Overaccumulation of H2S caused the depolymerization of F-actin bundles and inhibited root hair growth. Introduction of ACT2 carrying a Cys-287-to-Ser mutation into an act2-1 mutant partially suppressed H2S-dependent inhibition of root hair growth. We conclude that H2S regulates actin dynamics and affects root hair growth.
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Affiliation(s)
- Jisheng Li
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
- Biomass Energy Center for Arid and Semi-arid Lands, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Sisi Chen
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Xiaofeng Wang
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Cong Shi
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Huaxin Liu
- School of Environmental Science and Engineering, Shaanxi University of Science and Technology, Xi'an, Shaanxi 710021, China
| | - Jun Yang
- School of Environmental Science and Engineering, Shaanxi University of Science and Technology, Xi'an, Shaanxi 710021, China
| | - Wei Shi
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Junkang Guo
- School of Environmental Science and Engineering, Shaanxi University of Science and Technology, Xi'an, Shaanxi 710021, China
| | - Honglei Jia
- School of Environmental Science and Engineering, Shaanxi University of Science and Technology, Xi'an, Shaanxi 710021, China
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45
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Li H, Luo N, Wang W, Liu Z, Chen J, Zhao L, Tan L, Wang C, Qin Y, Li C, Xu T, Yang Z. The REN4 rheostat dynamically coordinates the apical and lateral domains of Arabidopsis pollen tubes. Nat Commun 2018; 9:2573. [PMID: 29968705 PMCID: PMC6030205 DOI: 10.1038/s41467-018-04838-w] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 05/11/2018] [Indexed: 11/08/2022] Open
Abstract
The dynamic maintenance of polar domains in the plasma membrane (PM) is critical for many fundamental processes, e.g., polar cell growth and growth guidance but remains poorly characterized. Rapid tip growth of Arabidopsis pollen tubes requires dynamic distribution of active ROP1 GTPase to the apical domain. Here, we show that clathrin-mediated endocytosis (CME) coordinates lateral REN4 with apical ROP1 signaling. REN4 interacted with but antagonized active ROP1. REN4 also interacts and co-localizes with CME components, but exhibits an opposite role to CME, which removes both REN4 and active ROP1 from the PM. Mathematical modeling shows that REN4 restrains the spatial distribution of active ROP1 and is important for the robustness of polarity control. Hence our results indicate that REN4 acts as a spatiotemporal rheostat by interacting with ROP1 to initiate their removal from the PM by CME, thereby coordinating a dynamic demarcation between apical and lateral domains during rapid tip growth.
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Affiliation(s)
- Hui Li
- Shanghai Center for Plant Stress Biology and Shanghai Institute of Plant Physiology and Ecolog, Shanghai Institutes for Biological Sciences Chinese Academy of Sciences, 201602, Shanghai, China
- Center for Plant Cell Biology, Institute of Integrative Genome Biology, and Department of Botany and Plant Sciences, University of California, Riverside, CA, 92508, USA
- School of Life Sciences, East China Normal University, 200241, Shanghai, China
| | - Nan Luo
- Center for Plant Cell Biology, Institute of Integrative Genome Biology, and Department of Botany and Plant Sciences, University of California, Riverside, CA, 92508, USA
- FAFU-UCR Joint Center for Horticultural Biology and Metebolomics, Institute of Science and Technology, Fujian Agriculture and Forestry University, 350002, Fuzhou, China
| | - Weidong Wang
- Center for Plant Cell Biology, Institute of Integrative Genome Biology, and Department of Botany and Plant Sciences, University of California, Riverside, CA, 92508, USA
| | - Zengyu Liu
- FAFU-UCR Joint Center for Horticultural Biology and Metebolomics, Institute of Science and Technology, Fujian Agriculture and Forestry University, 350002, Fuzhou, China
| | - Jisheng Chen
- Center for Plant Cell Biology, Institute of Integrative Genome Biology, and Department of Botany and Plant Sciences, University of California, Riverside, CA, 92508, USA
- FAFU-UCR Joint Center for Horticultural Biology and Metebolomics, Institute of Science and Technology, Fujian Agriculture and Forestry University, 350002, Fuzhou, China
| | - Liangtao Zhao
- Shanghai Center for Plant Stress Biology and Shanghai Institute of Plant Physiology and Ecolog, Shanghai Institutes for Biological Sciences Chinese Academy of Sciences, 201602, Shanghai, China
| | - Li Tan
- Shanghai Center for Plant Stress Biology and Shanghai Institute of Plant Physiology and Ecolog, Shanghai Institutes for Biological Sciences Chinese Academy of Sciences, 201602, Shanghai, China
| | - Chunyan Wang
- Shanghai Center for Plant Stress Biology and Shanghai Institute of Plant Physiology and Ecolog, Shanghai Institutes for Biological Sciences Chinese Academy of Sciences, 201602, Shanghai, China
| | - Yuan Qin
- FAFU-UCR Joint Center for Horticultural Biology and Metebolomics, Institute of Science and Technology, Fujian Agriculture and Forestry University, 350002, Fuzhou, China
| | - Chao Li
- School of Life Sciences, East China Normal University, 200241, Shanghai, China
| | - Tongda Xu
- Shanghai Center for Plant Stress Biology and Shanghai Institute of Plant Physiology and Ecolog, Shanghai Institutes for Biological Sciences Chinese Academy of Sciences, 201602, Shanghai, China
- FAFU-UCR Joint Center for Horticultural Biology and Metebolomics, Institute of Science and Technology, Fujian Agriculture and Forestry University, 350002, Fuzhou, China
| | - Zhenbiao Yang
- Center for Plant Cell Biology, Institute of Integrative Genome Biology, and Department of Botany and Plant Sciences, University of California, Riverside, CA, 92508, USA.
- FAFU-UCR Joint Center for Horticultural Biology and Metebolomics, Institute of Science and Technology, Fujian Agriculture and Forestry University, 350002, Fuzhou, China.
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46
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Kaštier P, Krasylenko YA, Martinčová M, Panteris E, Šamaj J, Blehová A. Cytoskeleton in the Parasitic Plant Cuscuta During Germination and Prehaustorium Formation. FRONTIERS IN PLANT SCIENCE 2018; 9:794. [PMID: 29971075 PMCID: PMC6018488 DOI: 10.3389/fpls.2018.00794] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 05/24/2018] [Indexed: 05/30/2023]
Abstract
Although cytoskeleton is a driving force for cell division and growth in higher plants, there is little evidence about its components in parasitic angiosperms. Microtubules and actin filaments in cells of shoot apical meristem and root-like structure of stem holoparasites European (C. europaea L.) and Eastern (C. monogyna Vahl.) dodders, as well as in prehaustorium, the specific organ adapted to parasitism, were visualized for the first time by immunolabeling and fluorescence microscopy. The significance of cytoskeletal elements during germination and prehaustorium formation was addressed by treatments with taxol, oryzalin, latrunculin B, cytochalasin B/D, jasplakinolide, and 2,3-butanedione monoxime. In shoot apical meristem many dividing cells were observed, in contrast to root-like structure, devoid of cell divisions. Cortical microtubules were oriented transversely and/or obliquely, while actin filaments were randomly distributed in cells of both organs. Furthermore, longitudinal cortical microtubules were present in digitate cells of prehaustorium, and transverse arrays were found in its file cells. Long and short random actin filaments were also observed in prehaustorium cells. Thus, it was shown that the cytoskeleton in dodder shoot cells is organized in a similar way to non-parasitic dicots, while cytoskeletal organization has some peculiarities in quickly senescing root-like structure and prehaustorium.
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Affiliation(s)
- Peter Kaštier
- Department of Plant Physiology, Faculty of Natural Sciences, Comenius University in Bratislava, Bratislava, Slovakia
| | - Yuliya A. Krasylenko
- Department of Cell Biology, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University Olomouc, Olomouc, Czechia
- Department of Cell Biology and Biotechnology, Institute of Food Biotechnology and Genomics, National Academy of Sciences of Ukraine, Kiev, Ukraine
| | - Michaela Martinčová
- Department of Plant Physiology, Faculty of Natural Sciences, Comenius University in Bratislava, Bratislava, Slovakia
| | - Emmanuel Panteris
- Department of Botany, School of Biology, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Jozef Šamaj
- Department of Cell Biology, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University Olomouc, Olomouc, Czechia
| | - Alžbeta Blehová
- Department of Plant Physiology, Faculty of Natural Sciences, Comenius University in Bratislava, Bratislava, Slovakia
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47
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Li G, Yang X, Zhang X, Song Y, Liang W, Zhang D. Rice Morphology Determinant-Mediated Actin Filament Organization Contributes to Pollen Tube Growth. PLANT PHYSIOLOGY 2018; 177:255-270. [PMID: 29581178 PMCID: PMC5933118 DOI: 10.1104/pp.17.01759] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 03/19/2018] [Indexed: 05/25/2023]
Abstract
For successful fertilization in angiosperms, rapid tip growth in pollen tubes delivers the male gamete into the ovules. The actin-binding protein-mediated organization of the actin cytoskeleton within the pollen tube plays a crucial role in this polarized process. However, the mechanism underlying the polarity of the actin filament (F-actin) array and behaviors in pollen tube growth remain largely unknown. Here, we demonstrate that an actin-organizing protein, Rice Morphology Determinant (RMD), a type II formin from rice (Oryza sativa), controls pollen tube growth by modulating the polarity and distribution of the F-actin array. The rice rmd mutant exhibits abnormal pollen tube growth and a decreased germination rate of the pollen grain in vitro and in vivo. The rmd pollen tubes display a disorganized F-actin pattern with disrupted apical actin density and shank longitudinal cable direction/arrangement, indicating the novel role of RMD in F-actin polarity during tip growth. Consistent with this role, RMD localizes at the tip of the rice pollen tube, which is essential for pollen tube growth and polarity as well as F-actin organization. Furthermore, the direction and characteristics of the RMD-guided F-actin array positively regulate the deposition of cell wall components and the pattern and velocity of cytoplasmic streaming during rice pollen tube growth. Collectively, our results suggest that RMD is essential for the spatial regulation of pollen tube growth via modulating F-actin organization and array orientation in rice. This work provides insights into tip-focused cell growth and polarity.
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Affiliation(s)
- Gang Li
- University of Adelaide-Shanghai Jiao Tong University Joint Laboratory for Plant Science and Breeding, School of Agriculture, Food, and Wine, University of Adelaide, Waite Campus, Urrbrae, South Australia 5064, Australia
| | - Xiujuan Yang
- University of Adelaide-Shanghai Jiao Tong University Joint Laboratory for Plant Science and Breeding, School of Agriculture, Food, and Wine, University of Adelaide, Waite Campus, Urrbrae, South Australia 5064, Australia
| | - Xiaoqing Zhang
- Joint International Research Laboratory of Metabolic and Developmental Sciences, Shanghai Jiao Tong University-University of Adelaide Joint Centre for Agriculture and Health, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Yu Song
- Joint International Research Laboratory of Metabolic and Developmental Sciences, Shanghai Jiao Tong University-University of Adelaide Joint Centre for Agriculture and Health, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Wanqi Liang
- Joint International Research Laboratory of Metabolic and Developmental Sciences, Shanghai Jiao Tong University-University of Adelaide Joint Centre for Agriculture and Health, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Dabing Zhang
- University of Adelaide-Shanghai Jiao Tong University Joint Laboratory for Plant Science and Breeding, School of Agriculture, Food, and Wine, University of Adelaide, Waite Campus, Urrbrae, South Australia 5064, Australia
- Joint International Research Laboratory of Metabolic and Developmental Sciences, Shanghai Jiao Tong University-University of Adelaide Joint Centre for Agriculture and Health, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
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48
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Sui X, Liu X, Lin W, Wu Z, Yang L. Targeting of rice grassy stunt virus pc6 protein to plasmodesmata requires the ER-to-Golgi secretory pathway and an actin-myosin VIII motility system. Arch Virol 2018; 163:1317-1323. [PMID: 29392491 DOI: 10.1007/s00705-018-3726-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 12/10/2017] [Indexed: 10/18/2022]
Abstract
The nonstructural protein pc6 encoded by rice grassy stunt virus (RGSV) plays a significant role in viral cell-to-cell movement, presumably by transport through plasmodesmata (PD). We confirmed the association of pc6 with PD, and also elucidated the mechanisms of protein targeting to PD. Several inhibitor treatments showed conclusively that pc6 is targeted to PD via the ER-to-Golgi secretory system and actin filaments. In addition, VIII-1 myosin was also found to be involved in pc6 PD targeting. Deletion mutants demonstrated that C-terminal amino acid residues 209-229 (transmembrane domain 2; TM2) are essential for pc6 to move through PD.
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Affiliation(s)
- Xuelian Sui
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Province Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China
| | - Xiaojuan Liu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Province Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China
| | - Wenwu Lin
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Province Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China
| | - Zujian Wu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Province Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China.
| | - Liang Yang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Province Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China.
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49
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Chen W, Gong P, Guo J, Li H, Li R, Xing W, Yang Z, Guan Y. Glycolysis regulates pollen tube polarity via Rho GTPase signaling. PLoS Genet 2018; 14:e1007373. [PMID: 29702701 PMCID: PMC5942846 DOI: 10.1371/journal.pgen.1007373] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 05/09/2018] [Accepted: 04/19/2018] [Indexed: 12/25/2022] Open
Abstract
As a universal energy generation pathway utilizing carbon metabolism, glycolysis plays an important housekeeping role in all organisms. Pollen tubes expand rapidly via a mechanism of polarized growth, known as tip growth, to deliver sperm for fertilization. Here, we report a novel and surprising role of glycolysis in the regulation of growth polarity in Arabidopsis pollen tubes via impingement of Rho GTPase-dependent signaling. We identified a cytosolic phosphoglycerate kinase (pgkc-1) mutant with accelerated pollen germination and compromised pollen tube growth polarity. pgkc-1 mutation greatly diminished apical exocytic vesicular distribution of REN1 RopGAP (Rop GTPase activating protein), leading to ROP1 hyper-activation at the apical plasma membrane. Consequently, pgkc-1 pollen tubes contained higher amounts of exocytic vesicles and actin microfilaments in the apical region, and showed reduced sensitivity to Brefeldin A and Latrunculin B, respectively. While inhibition of mitochondrial respiration could not explain the pgkc-1 phenotype, the glycolytic activity is indeed required for PGKc function in pollen tubes. Moreover, the pgkc-1 pollen tube phenotype was mimicked by the inhibition of another glycolytic enzyme. These findings highlight an unconventional regulatory function for a housekeeping metabolic pathway in the spatial control of a fundamental cellular process. Glycolysis, which breaks down glucose to produce energy, has long been considered a “housekeeping” pathway in living cells, i.e., it helps maintain basic cellular functions. Here, we found that the glycolysis pathway plays an unconventional regulatory role in cell polarity, i.e., the intrinsic asymmetry in the shape, structure, and organization of cellular components. Mutation in the gene encoding the glycolytic enzyme cytosolic phosphoglycerate kinase (PGKc) leads to swollen and shorter pollen tubes in Arabidopsis thaliana, which is associated with the over-activation of Rho GTPase—a master regulator of cell polarity. Our results suggest that this phenomenon is caused by a specific regulatory role of cytosolic glycolysis rather than the global energy supply or moonlighting functions of glycolytic enzymes that modulate pollen tube growth polarity. Our findings shed light on the diverse biological roles of glycolysis in plants beyond simple “housekeeping” functions.
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Affiliation(s)
- Wei Chen
- Shanghai Center for Plant Stress Biology, Chinese Academy of Sciences, Shanghai, China
- FAFU-UCR Joint Center for Horticultural Biology and Metabolomics, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
- University of Chinese Academy of Sciences, Shanghai, China
| | - Pingping Gong
- FAFU-UCR Joint Center for Horticultural Biology and Metabolomics, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Jingzhe Guo
- FAFU-UCR Joint Center for Horticultural Biology and Metabolomics, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
- Center for Plant Cell Biology, Institute of Integrated Genome Biology, and Department of Botany and Plant Sciences, University of California, Riverside, California, United States of America
| | - Hui Li
- Shanghai Center for Plant Stress Biology, Chinese Academy of Sciences, Shanghai, China
- Center for Plant Cell Biology, Institute of Integrated Genome Biology, and Department of Botany and Plant Sciences, University of California, Riverside, California, United States of America
| | - Ruizi Li
- FAFU-UCR Joint Center for Horticultural Biology and Metabolomics, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Weiman Xing
- Shanghai Center for Plant Stress Biology, Chinese Academy of Sciences, Shanghai, China
| | - Zhenbiao Yang
- FAFU-UCR Joint Center for Horticultural Biology and Metabolomics, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
- Center for Plant Cell Biology, Institute of Integrated Genome Biology, and Department of Botany and Plant Sciences, University of California, Riverside, California, United States of America
| | - Yuefeng Guan
- FAFU-UCR Joint Center for Horticultural Biology and Metabolomics, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
- * E-mail:
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50
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Simultaneous imaging and functional studies reveal a tight correlation between calcium and actin networks. Proc Natl Acad Sci U S A 2018; 115:E2869-E2878. [PMID: 29507239 DOI: 10.1073/pnas.1711037115] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Tip-growing cells elongate in a highly polarized manner via focused secretion of flexible cell-wall material. Calcium has been implicated as a vital factor in regulating the deposition of cell-wall material. However, deciphering the molecular and mechanistic calcium targets in vivo has remained challenging. Here, we investigated intracellular calcium dynamics in the moss Physcomitrella patens, which provides a system with an abundant source of genetically identical tip-growing cells, excellent cytology, and a large molecular genetic tool kit. To visualize calcium we used a genetically encoded cytosolic FRET probe, revealing a fluctuating tipward gradient with a complex oscillatory profile. Wavelet analysis coupled with a signal-sifting algorithm enabled the quantitative comparison of the calcium behavior in cells where growth was inhibited mechanically, pharmacologically, or genetically. We found that cells with suppressed growth have calcium oscillatory profiles with longer frequencies, suggesting that there is a feedback between the calcium gradient and growth. To investigate the mechanistic basis for this feedback we simultaneously imaged cytosolic calcium and actin, which has been shown to be essential for tip growth. We found that high cytosolic calcium promotes disassembly of a tip-focused actin spot, while low calcium promotes assembly. In support of this, abolishing the calcium gradient resulted in dramatic actin accumulation at the tip. Together these data demonstrate that tipward calcium is quantitatively linked to actin accumulation in vivo and that the moss P. patens provides a powerful system to uncover mechanistic links between calcium, actin, and growth.
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