1
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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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Liu YK, Li JJ, Xue QQ, Zhang SJ, Xie M, Cheng T, Wang HL, Liu CM, Chu JF, Pei YS, Jia BQ, Li J, Tian LJ, Fu AG, Hao YQ, Su H. Actin-bundling protein fimbrin serves as a new auxin biosynthesis orchestrator in Arabidopsis root tips. THE NEW PHYTOLOGIST 2024. [PMID: 39044442 DOI: 10.1111/nph.19959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Accepted: 06/25/2024] [Indexed: 07/25/2024]
Abstract
Plants delicately regulate endogenous auxin levels through the coordination of transport, biosynthesis, and inactivation, which is crucial for growth and development. While it is well-established that the actin cytoskeleton can regulate auxin levels by affecting polar transport, its potential role in auxin biosynthesis has remained largely unexplored. Using LC-MS/MS-based methods combined with fluorescent auxin marker detection, we observed a significant increase in root auxin levels upon deletion of the actin bundling proteins AtFIM4 and AtFIM5. Fluorescent observation, immunoblotting analysis, and biochemical approaches revealed that AtFIM4 and AtFIM5 affect the protein abundance of the key auxin synthesis enzyme YUC8 in roots. AtFIM4 and AtFIM5 regulate the auxin synthesis enzyme YUC8 at the protein level, with its degradation mediated by the 26S proteasome. This regulation modulates auxin synthesis and endogenous auxin levels in roots, consequently impacting root development. Based on these findings, we propose a molecular pathway centered on the 'actin cytoskeleton-26S proteasome-YUC8-auxin' axis that controls auxin levels. Our findings shed light on a new pathway through which plants regulate auxin synthesis. Moreover, this study illuminates a newfound role of the actin cytoskeleton in regulating plant growth and development, particularly through its involvement in maintaining protein homeostasis via the 26S proteasome.
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Affiliation(s)
- Yan-Kun Liu
- Key Laboratory of Resource Biology and Biotechnology in Western China (Northwest University), Ministry of Education, College of Life Sciences, Northwest University, Xi'an, 710069, China
| | - Jing-Jing Li
- Key Laboratory of Resource Biology and Biotechnology in Western China (Northwest University), Ministry of Education, College of Life Sciences, Northwest University, Xi'an, 710069, China
| | - Qiao-Qiao Xue
- Key Laboratory of Resource Biology and Biotechnology in Western China (Northwest University), Ministry of Education, College of Life Sciences, Northwest University, Xi'an, 710069, China
| | - Shu-Juan Zhang
- Key Laboratory of Resource Biology and Biotechnology in Western China (Northwest University), Ministry of Education, College of Life Sciences, Northwest University, Xi'an, 710069, China
| | - Min Xie
- Key Laboratory of Resource Biology and Biotechnology in Western China (Northwest University), Ministry of Education, College of Life Sciences, Northwest University, Xi'an, 710069, China
| | - Ting Cheng
- Key Laboratory of Resource Biology and Biotechnology in Western China (Northwest University), Ministry of Education, College of Life Sciences, Northwest University, Xi'an, 710069, China
| | - Hong-Li Wang
- Key Laboratory of Resource Biology and Biotechnology in Western China (Northwest University), Ministry of Education, College of Life Sciences, Northwest University, Xi'an, 710069, China
| | - Cui-Mei Liu
- National Centre for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Jin-Fang Chu
- National Centre for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China
- College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, 100039, China
| | - Yu-Sha Pei
- Key Laboratory of Resource Biology and Biotechnology in Western China (Northwest University), Ministry of Education, College of Life Sciences, Northwest University, Xi'an, 710069, China
| | - Bing-Qian Jia
- Key Laboratory of Resource Biology and Biotechnology in Western China (Northwest University), Ministry of Education, College of Life Sciences, Northwest University, Xi'an, 710069, China
| | - Jia Li
- Key Laboratory of Resource Biology and Biotechnology in Western China (Northwest University), Ministry of Education, College of Life Sciences, Northwest University, Xi'an, 710069, China
| | - Li-Jun Tian
- Key Laboratory of Resource Biology and Biotechnology in Western China (Northwest University), Ministry of Education, College of Life Sciences, Northwest University, Xi'an, 710069, China
| | - Ai-Gen Fu
- Key Laboratory of Resource Biology and Biotechnology in Western China (Northwest University), Ministry of Education, College of Life Sciences, Northwest University, Xi'an, 710069, China
| | - Ya-Qi Hao
- Key Laboratory of Resource Biology and Biotechnology in Western China (Northwest University), Ministry of Education, College of Life Sciences, Northwest University, Xi'an, 710069, China
| | - Hui Su
- Key Laboratory of Resource Biology and Biotechnology in Western China (Northwest University), Ministry of Education, College of Life Sciences, Northwest University, Xi'an, 710069, China
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3
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Hu D, Lin D, Yi S, Gao S, Lei T, Li W, Xu T. Comparative stigmatic transcriptomics reveals self and cross pollination responses to heteromorphic incompatibility in Plumbago auriculata Lam. Front Genet 2024; 15:1372644. [PMID: 38510275 PMCID: PMC10953596 DOI: 10.3389/fgene.2024.1372644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Accepted: 02/12/2024] [Indexed: 03/22/2024] Open
Abstract
"Heteromorphic self-incompatibility" (HetSI) in plants is a mechanism of defense to avoid self-pollination and promote outcrossing. However, the molecular mechanism underlying HetSI remains largely unknown. In this study, RNA-seq was conducted to explore the molecular mechanisms underlying self-compatible (SC, "T × P" and "P × T") and self-incompatible (SI, "T × T" and "P × P") pollination in the two types of flowers of Plumbago auriculata Lam. which is a representative HetSI plant. By comparing "T × P" vs. "T × T", 3773 (1407 upregulated and 2366 downregulated) differentially expressed genes (DEGs) were identified, 1261 DEGs between "P × T" and "P × P" (502 upregulated and 759 downregulated). The processes in which these DEGs were significantly enriched were "MAPK (Mitogen-Activated Protein Kinases-plant) signaling pathway", "plant-pathogen interaction","plant hormone signal transduction", and "pentose and glucuronate interconversion" pathways. Surprisingly, we discovered that under various pollination conditions, multiple notable genes that may be involved in HetSI exhibited distinct regulation. We can infer that the HetSI strategy might be unique in P. auriculata. It was similar to "sporophytic self-incompatibility" (SSI) but the HetSI mechanisms in pin and thrum flowers are diverse. In this study, new hypotheses and inferences were proposed, which can provide a reference for crop production and breeding.
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Affiliation(s)
- Di Hu
- College of Fine Art and Calligraphy, Sichuan Normal University, Chengdu, China
| | - Di Lin
- Sichuan Certification and Accreditation Association, Chengdu, China
| | - Shouli Yi
- College of Fine Art and Calligraphy, Sichuan Normal University, Chengdu, China
| | - Suping Gao
- College of Landscape Architecture, Sichuan Agricultural University, Chengdu, China
| | - Ting Lei
- College of Landscape Architecture, Sichuan Agricultural University, Chengdu, China
| | - Wenji Li
- School of Design, Chongqing Industry Polytechnic College, Chongqing, China
| | - Tingdan Xu
- College of Fine Art and Calligraphy, Sichuan Normal University, Chengdu, China
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4
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Wang J, Shen J, Xu Y, Jiang Y, Qu X, Zhao W, Wang Y, Huang S. Differential sensitivity of ADF isovariants to a pH gradient promotes pollen tube growth. J Cell Biol 2023; 222:e202206074. [PMID: 37610419 PMCID: PMC10445753 DOI: 10.1083/jcb.202206074] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 12/20/2022] [Accepted: 08/09/2023] [Indexed: 08/24/2023] Open
Abstract
The actin cytoskeleton is one of the targets of the pH gradient in tip-growing cells, but how cytosolic pH regulates the actin cytoskeleton remains largely unknown. We here demonstrate that Arabidopsis ADF7 and ADF10 function optimally at different pH levels when disassembling actin filaments. This differential pH sensitivity allows ADF7 and ADF10 to respond to the cytosolic pH gradient to regulate actin dynamics in pollen tubes. ADF7 is an unusual actin-depolymerizing factor with a low optimum pH in in vitro actin depolymerization assays. ADF7 plays a dominant role in promoting actin turnover at the pollen tube apex. ADF10 has a typically high optimum pH in in vitro assays and plays a dominant role in regulating the turnover and organization of subapical actin filaments. Thus, functional specification and cooperation of ADF isovariants with different pH sensitivities enable the coordination of the actin cytoskeleton with the cytosolic pH gradient to support pollen tube growth.
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Affiliation(s)
- Juan Wang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Jiangfeng Shen
- 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
| | - Yuxiang Jiang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Xiaolu Qu
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Wanying Zhao
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Yingjie Wang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Shanjin Huang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
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5
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Iqbal A, Aslam S, Akhtar S, Ali Q, Rao AQ, Husnain T. Over-expression of GhACTIN1 under the control of GhSCFP promoter improves cotton fiber and yield. Sci Rep 2023; 13:18377. [PMID: 37884648 PMCID: PMC10603119 DOI: 10.1038/s41598-023-45782-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 10/24/2023] [Indexed: 10/28/2023] Open
Abstract
Actin dynamics is pivotal in controlling cotton fiber elongation and the onset of secondary wall biosynthesis. We report that overexpression of GhACTIN1 under fiber fiber-specific promoter, GhSCFP, improves cotton fiber length, strength, and micronaire value. However, the effect of transgene has a more positive effect on fiber strength and micronaire value than fiber length. F-actin quantification and cellulose contents measurement in transgenic developing cotton fiber during the elongation phase showed an increase of up to 8.7% and 4.7% respectively. Additionally, physiological factors such as water use efficiency showed no significant change in transgenic cotton lines, while stomatal conductance and photosynthetic rate were significantly increased. Moreover, agronomical data determined that lint percentage (GOT) and seed cotton yield also increased up to 4.6% and 29.5% respectively, in transgenic cotton lines compared to the control lines. Our data demonstrate that the GhACTIN1 gene is a strong candidate gene for cotton fiber and yield improvement.
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Affiliation(s)
- Adnan Iqbal
- Centre of Excellence in Molecular Biology, University of Punjab, 87 West Canal Road, Lahore, 53700, Pakistan.
- Plant Breeding and Acclimatization Institute-National Research Institute, Radzikow, 05-870, Blonie, Poland.
| | - Sibgha Aslam
- Plant Breeding and Acclimatization Institute-National Research Institute, Radzikow, 05-870, Blonie, Poland
| | - Sidra Akhtar
- Centre of Excellence in Molecular Biology, University of Punjab, 87 West Canal Road, Lahore, 53700, Pakistan
| | - Qurban Ali
- Department of Plant Breeding and Genetics, University of the Punjab, Lahore, Pakistan.
| | - Abdul Qayyum Rao
- Centre of Excellence in Molecular Biology, University of Punjab, 87 West Canal Road, Lahore, 53700, Pakistan
| | - Tayyab Husnain
- Centre of Excellence in Molecular Biology, University of Punjab, 87 West Canal Road, Lahore, 53700, Pakistan
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6
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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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7
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Xiang X, Zhang S, Li E, Shi XL, Zhi JY, Liang X, Yin GM, Qin Z, Li S, Zhang Y. RHO OF PLANT proteins are essential for pollen germination in Arabidopsis. PLANT PHYSIOLOGY 2023; 193:140-155. [PMID: 36974907 DOI: 10.1093/plphys/kiad196] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 02/21/2023] [Accepted: 03/06/2023] [Indexed: 06/18/2023]
Abstract
Pollen germination is a process of polarity establishment, through which a single and unique growth axis is established. Although most of the intracellular activities associated with pollen germination are controlled by RHO OF PLANTs (ROPs) and increased ROP activation accompanies pollen germination, a critical role of ROPs in this process has not yet been demonstrated. Here, by genomic editing of all 4 Arabidopsis (Arabidopsis thaliana) ROPs that are preferentially expressed in pollen, we showed that ROPs are essential for polarity establishment during pollen germination. We further identified and characterized 2 ROP effectors in pollen germination (REGs) through genome-wide interactor screening, boundary of ROP domain (BDR) members BDR8 and BDR9, whose functional loss also resulted in no pollen germination. BDR8 and BDR9 were distributed in the cytosol and the vegetative nucleus of mature pollen grains but redistributed to the plasma membrane (PM) of the germination site and to the apical PM of growing pollen tubes. We demonstrated that the PM redistribution of BDR8 and BDR9 during pollen germination relies on ROPs but not vice versa. Furthermore, enhanced expression of BDR8 partially restored germination of rop1 pollen but had no effects on that of the quadruple rop pollen, supporting their genetic epistasis. Results presented here demonstrate an ROP signaling route essential for pollen germination, which supports evolutionarily conserved roles of Rho GTPases in polarity establishment.
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Affiliation(s)
- Xiaojiao Xiang
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an 271018, China
| | - Shuzhan Zhang
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an 271018, China
| | - En Li
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an 271018, China
| | - Xue-Lian Shi
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an 271018, China
| | - Jing-Yu Zhi
- Department of Plant Biology and Ecology, College of Life Sciences, Nankai University, Tian'jin 300071, China
| | - Xin Liang
- Department of Plant Biology and Ecology, College of Life Sciences, Nankai University, Tian'jin 300071, China
| | - Gui-Min Yin
- Department of Plant Biology and Ecology, College of Life Sciences, Nankai University, Tian'jin 300071, China
| | - Zheng Qin
- Department of Plant Biology and Ecology, College of Life Sciences, Nankai University, Tian'jin 300071, China
| | - Sha Li
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an 271018, China
| | - Yan Zhang
- Department of Plant Biology and Ecology, College of Life Sciences, Nankai University, Tian'jin 300071, China
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8
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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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9
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Iqbal A, Aslam S, Ahmed M, Khan F, Ali Q, Han S. Role of Actin Dynamics and GhACTIN1 Gene in Cotton Fiber Development: A Prototypical Cell for Study. Genes (Basel) 2023; 14:1642. [PMID: 37628693 PMCID: PMC10454433 DOI: 10.3390/genes14081642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 08/13/2023] [Accepted: 08/15/2023] [Indexed: 08/27/2023] Open
Abstract
Cotton crop is considered valuable for its fiber and seed oil. Cotton fiber is a single-celled outgrowth from the ovule epidermis, and it is a very dynamic cell for study. It has four distinct but overlapping developmental stages: initiation, elongation, secondary cell wall synthesis, and maturation. Among the various qualitative characteristics of cotton fiber, the important ones are the cotton fiber staple length, tensile strength, micronaire values, and fiber maturity. Actin dynamics are known to play an important role in fiber elongation and maturation. The current review gives an insight into the cotton fiber developmental stages, the qualitative traits associated with cotton fiber, and the set of genes involved in regulating these developmental stages and fiber traits. This review also highlights some prospects for how biotechnological approaches can improve cotton fiber quality.
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Affiliation(s)
- Adnan Iqbal
- School of Biological Sciences and Technology, Liupanshui Normal University, Liupanshui 553004, China;
- Plant Breeding and Acclimatization Institute—National Research Institute, Radzikow, 05-870 Blonie, Poland
| | - Sibgha Aslam
- Plant Breeding and Acclimatization Institute—National Research Institute, Radzikow, 05-870 Blonie, Poland
| | - Mukhtar Ahmed
- Government Boys College Sokasan, Higher Education Department, Azad Jammu and Kashmir, Bhimber 10040, Pakistan
| | - Fahad Khan
- Department of Plant Protection, Faculty of Agricultural Sciences, Ghazi University, Dera Ghazi Khan 33001, Pakistan
| | - Qurban Ali
- Department of Plant Breeding and Genetics, Faculty of Agricultural Sciences, University of the Punjab, Lahore 54590, Pakistan
| | - Shiming Han
- School of Biological Sciences and Technology, Liupanshui Normal University, Liupanshui 553004, China;
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10
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Yu SX, Hu LQ, Yang LH, Zhang T, Dai RB, Zhang YJ, Xie ZP, Lin WH. RLI2 regulates Arabidopsis female gametophyte and embryo development by facilitating the assembly of the translational machinery. Cell Rep 2023; 42:112741. [PMID: 37421624 DOI: 10.1016/j.celrep.2023.112741] [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: 10/19/2022] [Revised: 04/01/2023] [Accepted: 06/20/2023] [Indexed: 07/10/2023] Open
Abstract
Eukaryotic protein translation is a complex process that requires the participation of different proteins. Defects in the translational machinery often result in embryonic lethality or severe growth defects. Here, we report that RNase L inhibitor 2/ATP-BINDING CASSETTE E2 (RLI2/ABCE2) regulates translation in Arabidopsis thaliana. Null mutation of rli2 is gametophytic and embryonic lethal, whereas knockdown of RLI2 causes pleiotropic developmental defects. RLI2 interacts with several translation-related factors. Knockdown of RLI2 affects the translational efficiency of a subset of proteins involved in translation regulation and embryo development, indicating that RLI2 has critical roles in these processes. In particular, RLI2 knockdown mutant exhibits decreased expression of genes involved in auxin signaling and female gametophyte and embryo development. Therefore, our results reveal that RLI2 facilitates assembly of the translational machinery and indirectly modulates auxin signaling to regulate plant growth and development.
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Affiliation(s)
- Shi-Xia Yu
- The Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China; Shanghai Collaborative Innovation Center of Agri-Seeds/Joint Center for Single Cell Biology, Shanghai Jiao Tong University, Shanghai 200240, China; School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Li-Qin Hu
- The Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China; Shanghai Collaborative Innovation Center of Agri-Seeds/Joint Center for Single Cell Biology, Shanghai Jiao Tong University, Shanghai 200240, China; School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Lu-Han Yang
- The Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Tao Zhang
- The Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Ruo-Bing Dai
- Zhiyuan College, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Yan-Jie Zhang
- The Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Zhi-Ping Xie
- The Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Wen-Hui Lin
- The Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China; Shanghai Collaborative Innovation Center of Agri-Seeds/Joint Center for Single Cell Biology, Shanghai Jiao Tong University, Shanghai 200240, China.
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11
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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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12
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Zhang Y, An B, Wang W, Zhang B, He C, Luo H, Wang Q. Actin-bundling protein fimbrin regulates pathogenicity via organizing F-actin dynamics during appressorium development in Colletotrichum gloeosporioides. MOLECULAR PLANT PATHOLOGY 2022; 23:1472-1486. [PMID: 35791045 PMCID: PMC9452767 DOI: 10.1111/mpp.13242] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 06/12/2022] [Accepted: 06/14/2022] [Indexed: 06/15/2023]
Abstract
Anthracnose caused by Colletotrichum gloeosporioides leads to serious economic loss to rubber tree yield and other tropical crops. The appressorium, a specialized dome-shaped infection structure, plays a crucial role in the pathogenesis of C. gloeosporioides. However, the mechanism of how actin cytoskeleton dynamics regulate appressorium formation and penetration remains poorly defined in C. gloeosporioides. In this study, an actin cross-linking protein fimbrin homologue (CgFim1) was identified in C. gloeosporioides, and the knockout of CgFim1 led to impairment in vegetative growth, conidiation, and pathogenicity. We then investigated the roles of CgFim1 in the dynamic organization of the actin cytoskeleton. We observed that actin patches and cables localized at the apical and subapical regions of the hyphal tip, and showed a disc-to-ring dynamic around the pore during appressorium development. CgFim1 showed a similar distribution pattern to the actin cytoskeleton. Moreover, knockout of CgFim1 affected the polarity of the actin cytoskeleton in the hyphal tip and disrupted the actin dynamics and ring structure formation in the appressorium, which prevented polar growth and appressorium development. The CgFim1 mutant also interfered with the septin structure formation. This caused defects in pore wall overlay formation, pore contraction, and the extension of the penetration peg. These results reveal the mechanism by which CgFim1 regulates the growth and pathogenicity of C. gloeosporioides by organizing the actin cytoskeleton.
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Affiliation(s)
- Yi Zhang
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource, Key Laboratory of Biotechnology of Salt Tolerant Crops of Hainan ProvinceCollege of Tropical Crops, Hainan UniversityHaikouChina
- Sanya Nanfan Research Institute of Hainan University, Hainan Yazhou Bay Seed LaboratorySanyaChina
| | - Bang An
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource, Key Laboratory of Biotechnology of Salt Tolerant Crops of Hainan ProvinceCollege of Tropical Crops, Hainan UniversityHaikouChina
- Sanya Nanfan Research Institute of Hainan University, Hainan Yazhou Bay Seed LaboratorySanyaChina
| | - Wenfeng Wang
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource, Key Laboratory of Biotechnology of Salt Tolerant Crops of Hainan ProvinceCollege of Tropical Crops, Hainan UniversityHaikouChina
| | - Bei Zhang
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource, Key Laboratory of Biotechnology of Salt Tolerant Crops of Hainan ProvinceCollege of Tropical Crops, Hainan UniversityHaikouChina
- Sanya Nanfan Research Institute of Hainan University, Hainan Yazhou Bay Seed LaboratorySanyaChina
| | - Chaozu He
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource, Key Laboratory of Biotechnology of Salt Tolerant Crops of Hainan ProvinceCollege of Tropical Crops, Hainan UniversityHaikouChina
- Sanya Nanfan Research Institute of Hainan University, Hainan Yazhou Bay Seed LaboratorySanyaChina
| | - Hongli Luo
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource, Key Laboratory of Biotechnology of Salt Tolerant Crops of Hainan ProvinceCollege of Tropical Crops, Hainan UniversityHaikouChina
- Sanya Nanfan Research Institute of Hainan University, Hainan Yazhou Bay Seed LaboratorySanyaChina
| | - Qiannan Wang
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource, Key Laboratory of Biotechnology of Salt Tolerant Crops of Hainan ProvinceCollege of Tropical Crops, Hainan UniversityHaikouChina
- Sanya Nanfan Research Institute of Hainan University, Hainan Yazhou Bay Seed LaboratorySanyaChina
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13
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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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14
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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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15
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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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16
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Dong B, Yang Q, Song Z, Niu L, Cao H, Liu T, Du T, Yang W, Qi M, Chen T, Wang M, Jin H, Meng D, Fu Y. Hyperoside promotes pollen tube growth by regulating the depolymerization effect of actin-depolymerizing factor 1 on microfilaments in okra. HORTICULTURE RESEARCH 2021; 8:145. [PMID: 34193835 PMCID: PMC8245483 DOI: 10.1038/s41438-021-00578-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 03/14/2021] [Accepted: 04/07/2021] [Indexed: 06/13/2023]
Abstract
Mature pollen germinates rapidly on the stigma, extending its pollen tube to deliver sperm cells to the ovule for fertilization. The success of this process is an important factor that limits output. The flavonoid content increased significantly during pollen germination and pollen tube growth, which suggests it may play an important role in these processes. However, the specific mechanism of this involvement has been little researched. Our previous research found that hyperoside can prolong the flowering period of Abelmoschus esculentus (okra), but its specific mechanism is still unclear. Therefore, in this study, we focused on the effect of hyperoside in regulating the actin-depolymerizing factor (ADF), which further affects the germination and growth of pollen. We found that hyperoside can prolong the effective pollination period of okra by 2-3-fold and promote the growth of pollen tubes in the style. Then, we used Nicotiana benthamiana cells as a research system and found that hyperoside accelerates the depolymerization of intercellular microfilaments. Hyperoside can promote pollen germination and pollen tube elongation in vitro. Moreover, AeADF1 was identified out of all AeADF genes as being highly expressed in pollen tubes in response to hyperoside. In addition, hyperoside promoted AeADF1-mediated microfilament dissipation according to microfilament severing experiments in vitro. In the pollen tube, the gene expression of AeADF1 was reduced to 1/5 by oligonucleotide transfection. The decrease in the expression level of AeADF1 partially reduced the promoting effect of hyperoside on pollen germination and pollen tube growth. This research provides new research directions for flavonoids in reproductive development.
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Affiliation(s)
- Biying Dong
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, College of Forestry, Beijing Forestry University, Beijing, 100000, China
| | - Qing Yang
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, College of Forestry, Beijing Forestry University, Beijing, 100000, China
| | - Zhihua Song
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, College of Forestry, Beijing Forestry University, Beijing, 100000, China
| | - Lili Niu
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, College of Forestry, Beijing Forestry University, Beijing, 100000, China
| | - Hongyan Cao
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, College of Forestry, Beijing Forestry University, Beijing, 100000, China
| | - Tengyue Liu
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, College of Forestry, Beijing Forestry University, Beijing, 100000, China
| | - Tingting Du
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, College of Forestry, Beijing Forestry University, Beijing, 100000, China
| | - Wanlong Yang
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, College of Forestry, Beijing Forestry University, Beijing, 100000, China
| | - Meng Qi
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, College of Forestry, Beijing Forestry University, Beijing, 100000, China
| | - Ting Chen
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, College of Forestry, Beijing Forestry University, Beijing, 100000, China
| | - Mengying Wang
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, College of Forestry, Beijing Forestry University, Beijing, 100000, China
| | - Haojie Jin
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, College of Forestry, Beijing Forestry University, Beijing, 100000, China
| | - Dong Meng
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, College of Forestry, Beijing Forestry University, Beijing, 100000, China.
| | - Yujie Fu
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, College of Forestry, Beijing Forestry University, Beijing, 100000, China.
- Key Laboratory of Forest Plant Ecology, Ministry of Education, Northeast Forestry University, Harbin, 150000, China.
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17
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Hayashi M, Palmgren M. The quest for the central players governing pollen tube growth and guidance. PLANT PHYSIOLOGY 2021; 185:682-693. [PMID: 33793904 PMCID: PMC8133568 DOI: 10.1093/plphys/kiaa092] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 12/06/2020] [Indexed: 05/02/2023]
Abstract
Recent insights into the mechanism of pollen tube growth and guidance point to the importance of H+ dynamics, which are regulated by the plasma membrane H+-ATPase.
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Affiliation(s)
- Maki Hayashi
- Department for Plant and Environmental Sciences, University of Copenhagen, Frederiksberg C, Copenhagen, Denmark
| | - Michael Palmgren
- Department for Plant and Environmental Sciences, University of Copenhagen, Frederiksberg C, Copenhagen, Denmark
- International Research Centre for Environmental Membrane Biology, Foshan University, Foshan 528000,China
- Author for communication:
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18
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Diao M, Huang S. An Update on the Role of the Actin Cytoskeleton in Plasmodesmata: A Focus on Formins. FRONTIERS IN PLANT SCIENCE 2021; 12:647123. [PMID: 33659020 PMCID: PMC7917184 DOI: 10.3389/fpls.2021.647123] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 01/26/2021] [Indexed: 06/12/2023]
Abstract
Cell-to-cell communication in plants is mediated by plasmodesmata (PD) whose permeability is tightly regulated during plant growth and development. The actin cytoskeleton has been implicated in regulating the permeability of PD, but the underlying mechanism remains largely unknown. Recent characterization of PD-localized formin proteins has shed light on the role and mechanism of action of actin in regulating PD-mediated intercellular trafficking. In this mini-review article, we will describe the progress in this area.
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Affiliation(s)
- Min Diao
- iHuman Institute, Shanghai Tech University, Shanghai, China
| | - Shanjin Huang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
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19
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Zhou PM, Liang Y, Mei J, Liao HZ, Wang P, Hu K, Chen LQ, Zhang XQ, Ye D. The Arabidopsis AGC kinases NDR2/4/5 interact with MOB1A/1B and play important roles in pollen development and germination. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 105:1035-1052. [PMID: 33215783 DOI: 10.1111/tpj.15085] [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: 05/09/2020] [Revised: 09/29/2020] [Accepted: 10/21/2020] [Indexed: 06/11/2023]
Abstract
Pollen formation and pollen tube growth are essential for the delivery of male gametes into the female embryo sac for double fertilization. Little is known about the mechanisms that regulate the late developmental process of pollen formation and pollen germination. In this study, we characterized a group of Arabidopsis AGC kinase proteins, NDR2/4/5, involved in pollen development and pollen germination. The NDR2/4/5 genes are mainly expressed in pollen grains at the late developmental stages and in pollen tubes. They function redundantly in pollen formation and pollen germination. At the tricellular stages, the ndr2 ndr4 ndr5 mutant pollen grains exhibit an abnormal accumulation of callose, precocious germination and burst in anthers, leading to a drastic reduction in fertilization and a reduced seed set. NDR2/4/5 proteins can interact with another group of proteins (MOB1A/1B) homologous to the MOB proteins from the Hippo signaling pathway in yeast and animals. The Arabidopsis mob1a mob1b mutant pollen grains also have a phenotype similar to that of ndr2 ndr4 ndr5 pollen grains. These results provide new evidence demonstrating that the Hippo signaling components are conserved in plants and play important roles in sexual plant reproduction.
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Affiliation(s)
- Peng-Min Zhou
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Yan Liang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Juan Mei
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Hong-Ze Liao
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Pu Wang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Ke Hu
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Li-Qun Chen
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Xue-Qin Zhang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, China
| | - De Ye
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, China
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20
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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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21
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Flores-Tornero M, Vogler F, Mutwil M, Potěšil D, Ihnatová I, Zdráhal Z, Sprunck S, Dresselhaus T. Transcriptomic and Proteomic Insights into Amborella trichopoda Male Gametophyte Functions. PLANT PHYSIOLOGY 2020; 184:1640-1657. [PMID: 32989009 PMCID: PMC7723084 DOI: 10.1104/pp.20.00837] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 09/16/2020] [Indexed: 05/27/2023]
Abstract
Flowering plants (angiosperms) are characterized by pollen tubes (PTs; male gametophytes) carrying two immobile sperm cells that grow over long distances through the carpel toward the ovules, where double fertilization is executed. It is not understood how these reproductive structures evolved, which genes occur de novo in male gametophytes of angiosperms, and to which extent PT functions are conserved among angiosperms. To contribute to a deeper understanding of the evolution of gametophyte functions, we generated RNA sequencing data from seven reproductive and two vegetative control tissues of the basal angiosperm Amborella trichopoda and complemented these with proteomic data of pollen grains (PGs) and PTs. The eudicot model plant Arabidopsis (Arabidopsis thaliana) served as a reference organism for data analysis, as more than 200 genes have been associated with male gametophyte functions in this species. We describe methods to collect bicellular A. trichopoda PGs, to induce their germination in vitro, and to monitor PT growth and germ cell division. Transcriptomic and proteomic analyses indicate that A. trichopoda PGs are prepared for germination requiring lipids, energy, but likely also reactive oxygen species, while PTs are especially characterized by catabolic/biosynthetic and transport processes including cell wall biosynthesis and gene regulation. Notably, a number of pollen-specific genes were lacking in Arabidopsis, and the number of genes involved in pollen signaling is significantly reduced in A. trichopoda In conclusion, we provide insight into male gametophyte functions of the most basal angiosperm and establish a valuable resource for future studies on the evolution of flowering plants.
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Affiliation(s)
- María Flores-Tornero
- Cell Biology and Plant Biochemistry, University of Regensburg, 93053 Regensburg, Germany
| | - Frank Vogler
- Cell Biology and Plant Biochemistry, University of Regensburg, 93053 Regensburg, Germany
| | - Marek Mutwil
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - David Potěšil
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Masaryk University, CZ-62500 Brno, Czech Republic
| | - Ivana Ihnatová
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Masaryk University, CZ-62500 Brno, Czech Republic
- RECETOX, Faculty of Science, Masaryk University, CZ-62500 Brno, Czech Republic
| | - Zbyněk Zdráhal
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Masaryk University, CZ-62500 Brno, Czech Republic
| | - Stefanie Sprunck
- Cell Biology and Plant Biochemistry, University of Regensburg, 93053 Regensburg, Germany
| | - Thomas Dresselhaus
- Cell Biology and Plant Biochemistry, University of Regensburg, 93053 Regensburg, Germany
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22
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Luo X, Ou Y, Li R, He Y. Maternal transmission of the epigenetic 'memory of winter cold' in Arabidopsis. NATURE PLANTS 2020; 6:1211-1218. [PMID: 32958896 DOI: 10.1038/s41477-020-00774-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 08/24/2020] [Indexed: 05/11/2023]
Abstract
Some plants can 'remember' past environmental experience to become adapted to a given environment. For instance, after experiencing prolonged low-temperature exposure in winter (winter cold), vernalization-responsive plants remember past cold experience when temperature rises in spring, to acquire competence to flower at a later season favourable for seed production1,2. In Arabidopsis thaliana, prolonged cold induces silencing of the potent floral repressor FLOWERING LOCUS C (FLC) by Polycomb group (PcG) chromatin modifiers. This Polycomb-repressed chromatin state is epigenetically maintained and thus 'memorized' in subsequent growth and development upon return to warmth1,3. 'Memory of winter cold' has been viewed as being mitotically stable but meiotically unstable3-5, and thus not to be transmitted intergenerationally. In general, whether and how chromatin-mediated environmental memories are transmitted across generations are unknown in plants. Here, we show that the cold-induced Polycomb-repressed chromatin state at FLC or memory of winter cold is maintained in the egg cell, that is meiotically stable in the process of female gamete formation, and provide evidence that this Polycomb-mediated memory is not maintained in the sperm cell. Moreover, we show that this cold memory is inherited maternally but not paternally to the zygote and early embryos. Our study demonstrates and further provides mechanistic insights into intergenerational transmission of chromatin state-mediated environmental memories in plants.
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Affiliation(s)
- Xiao Luo
- Shanghai Center for Plant Stress Biology & National Key Laboratory of Plant Molecular Genetics, Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Shanghai, China
| | - Yang Ou
- Shanghai Center for Plant Stress Biology & National Key Laboratory of Plant Molecular Genetics, Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Renjie Li
- Shanghai Center for Plant Stress Biology & National Key Laboratory of Plant Molecular Genetics, Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Shanghai, China
- School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Yuehui He
- Shanghai Center for Plant Stress Biology & National Key Laboratory of Plant Molecular Genetics, Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Shanghai, China.
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23
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Hoffmann RD, Portes MT, Olsen LI, Damineli DSC, Hayashi M, Nunes CO, Pedersen JT, Lima PT, Campos C, Feijó JA, Palmgren M. Plasma membrane H +-ATPases sustain pollen tube growth and fertilization. Nat Commun 2020; 11:2395. [PMID: 32409656 PMCID: PMC7224221 DOI: 10.1038/s41467-020-16253-1] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 04/23/2020] [Indexed: 01/18/2023] Open
Abstract
Pollen tubes are highly polarized tip-growing cells that depend on cytosolic pH gradients for signaling and growth. Autoinhibited plasma membrane proton (H+) ATPases (AHAs) have been proposed to energize pollen tube growth and underlie cell polarity, however, mechanistic evidence for this is lacking. Here we report that the combined loss of AHA6, AHA8, and AHA9 in Arabidopsis thaliana delays pollen germination and causes pollen tube growth defects, leading to drastically reduced fertility. Pollen tubes of aha mutants had reduced extracellular proton (H+) and anion fluxes, reduced cytosolic pH, reduced tip-to-shank proton gradients, and defects in actin organization. Furthermore, mutant pollen tubes had less negative membrane potentials, substantiating a mechanistic role for AHAs in pollen tube growth through plasma membrane hyperpolarization. Our findings define AHAs as energy transducers that sustain the ionic circuit defining the spatial and temporal profiles of cytosolic pH, thereby controlling downstream pH-dependent mechanisms essential for pollen tube elongation, and thus plant fertility.
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Affiliation(s)
- Robert D Hoffmann
- Department for Plant and Environmental Sciences, University of Copenhagen, 1871, Frederiksberg C, Denmark
| | - Maria Teresa Portes
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, 20742, USA
| | - Lene Irene Olsen
- Department for Plant and Environmental Sciences, University of Copenhagen, 1871, Frederiksberg C, Denmark
| | - Daniel Santa Cruz Damineli
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, 20742, USA
- Department of Pediatrics, Faculdade de Medicina da Universidade de São Paulo, São Paulo, SP, 01246-903, Brazil
| | - Maki Hayashi
- Department for Plant and Environmental Sciences, University of Copenhagen, 1871, Frederiksberg C, Denmark
| | - Custódio O Nunes
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, 20742, USA
| | - Jesper T Pedersen
- Department for Plant and Environmental Sciences, University of Copenhagen, 1871, Frederiksberg C, Denmark
| | - Pedro T Lima
- Instituto Gulbenkian de Ciência, Oeiras, 2780-156, Portugal
| | - Cláudia Campos
- Instituto Gulbenkian de Ciência, Oeiras, 2780-156, Portugal
| | - José A Feijó
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, 20742, USA.
- Instituto Gulbenkian de Ciência, Oeiras, 2780-156, Portugal.
| | - Michael Palmgren
- Department for Plant and Environmental Sciences, University of Copenhagen, 1871, Frederiksberg C, Denmark.
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24
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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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25
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Li YB, Xu R, Liu C, Shen N, Han LB, Tang D. Magnaporthe oryzae fimbrin organizes actin networks in the hyphal tip during polar growth and pathogenesis. PLoS Pathog 2020; 16:e1008437. [PMID: 32176741 PMCID: PMC7098657 DOI: 10.1371/journal.ppat.1008437] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 03/26/2020] [Accepted: 02/26/2020] [Indexed: 01/19/2023] Open
Abstract
Magnaporthe oryzae causes rice blast disease, but little is known about the dynamic restructuring of the actin cytoskeleton during its polarized tip growth and pathogenesis. Here, we used super-resolution live-cell imaging to investigate the dynamic organization of the actin cytoskeleton in M. oryzae during hyphal tip growth and pathogenesis. We observed a dense actin network at the apical region of the hyphae and actin filaments originating from the Spitzenkörper (Spk, the organizing center for hyphal growth and development) that formed branched actin bundles radiating to the cell membrane. The actin cross-linking protein Fimbrin (MoFim1) helps organize this actin distribution. MoFim1 localizes to the actin at the subapical collar, the actin bundles, and actin at the Spk. Knockout of MoFim1 resulted in impaired Spk maintenance and reduced actin bundle formation, preventing polar growth, vesicle transport, and the expansion of hyphae in plant cells. Finally, transgenic rice (Oryza sativa) expressing RNA hairpins targeting MoFim1 exhibited improved resistance to M. oryzae infection, indicating that MoFim1 represents an excellent candidate for M. oryzae control. These results reveal the dynamics of actin assembly in M. oryzae during hyphal tip development and pathogenesis, and they suggest a mechanism in which MoFim1 organizes such actin networks.
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Affiliation(s)
- Yuan-Bao Li
- State Key Laboratory of Ecological Control of Fujian-Taiwan Crop Pests, Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Plant Immunity Center, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
- College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Rui Xu
- State Key Laboratory of Ecological Control of Fujian-Taiwan Crop Pests, Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Plant Immunity Center, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
- College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Chengyu Liu
- State Key Laboratory of Ecological Control of Fujian-Taiwan Crop Pests, Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Plant Immunity Center, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
- College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Ningning Shen
- State Key Laboratory of Ecological Control of Fujian-Taiwan Crop Pests, Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Plant Immunity Center, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
- College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Li-Bo Han
- State Key Laboratory of Ecological Control of Fujian-Taiwan Crop Pests, Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Plant Immunity Center, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Dingzhong Tang
- State Key Laboratory of Ecological Control of Fujian-Taiwan Crop Pests, Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Plant Immunity Center, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
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26
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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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27
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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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28
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Li X, Diao M, Zhang Y, Chen G, Huang S, Chen N. Guard Cell Microfilament Analyzer Facilitates the Analysis of the Organization and Dynamics of Actin Filaments in Arabidopsis Guard Cells. Int J Mol Sci 2019; 20:ijms20112753. [PMID: 31195605 PMCID: PMC6600335 DOI: 10.3390/ijms20112753] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 05/26/2019] [Accepted: 05/28/2019] [Indexed: 11/29/2022] Open
Abstract
The actin cytoskeleton is involved in regulating stomatal movement, which forms distinct actin arrays within guard cells of stomata with different apertures. How those actin arrays are formed and maintained remains largely unexplored. Elucidation of the dynamic behavior of differently oriented actin filaments in guard cells will enhance our understanding in this regard. Here, we initially developed a program called ‘guard cell microfilament analyzer’ (GCMA) that enables the selection of individual actin filaments and analysis of their orientations semiautomatically in guard cells. We next traced the dynamics of individual actin filaments and performed careful quantification in open and closed stomata. We found that de novo nucleation of actin filaments occurs at both dorsal and ventral sides of guard cells from open and closed stomata. Interestingly, most of the nucleated actin filaments elongate radially and longitudinally in open and closed stomata, respectively. Strikingly, radial filaments tend to form bundles whereas longitudinal filaments tend to be removed by severing and depolymerization in open stomata. By contrast, longitudinal filaments tend to form bundles that are severed less frequently in closed stomata. These observations provide insights into the formation and maintenance of distinct actin arrays in guard cells in stomata of different apertures.
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Affiliation(s)
- Xin Li
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
- University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Min Diao
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.
- iHuman Institute, Shanghai Tech University, Shanghai 201210, China.
| | - Yanan Zhang
- OLYMPUS (CHINA) CO., LTD, Beijing 100027, China.
| | - Guanlin Chen
- Baidu Online Network Technology (Beijing) CO., LTD, Beijing 100193, China.
| | - Shanjin Huang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.
| | - Naizhi Chen
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
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29
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Zhang R, Qu X, Zhang M, Jiang Y, Dai A, Zhao W, Cao D, Lan Y, Yu R, Wang H, Huang S. The Balance between Actin-Bundling Factors Controls Actin Architecture in Pollen Tubes. iScience 2019; 16:162-176. [PMID: 31181400 PMCID: PMC6556835 DOI: 10.1016/j.isci.2019.05.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 04/29/2019] [Accepted: 05/21/2019] [Indexed: 11/19/2022] Open
Abstract
How actin-bundling factors cooperatively regulate shank-localized actin bundles remains largely unexplored. Here we demonstrate that FIM5 and PLIM2a/PLIM2b decorate shank-localized actin bundles and that loss of function of PLIM2a and/or PLIM2b suppresses phenotypes associated with fim5 mutants. Specifically, knockout of PLIM2a and/or PLIM2b partially suppresses the disorganized actin bundle and intracellular trafficking phenotype in fim5 pollen tubes. PLIM2a/PLIM2b generates thick but loosely packed actin bundles, whereas FIM5 generates thin but tight actin bundles that tend to be cross-linked into networks in vitro. Furthermore, PLIM2a/PLIM2b and FIM5 compete for binding to actin filaments in vitro, and PLIM2a/PLIM2b decorate disorganized actin bundles in fim5 pollen tubes. These data together suggest that the disorganized actin bundles in fim5 mutants are at least partially due to gain of function of PLIM2a/PLIM2b. Our data suggest that the balance between FIM5 and PLIM2a/PLIM2b is crucial for the normal bundling and organization of shank-localized actin bundles in pollen tubes. The transcription of PLIM2a and PLIM2b is upregulated in fim5 pollen tubes Downregulation of PLIM2a and/or PLIM2b suppresses the defects in fim5 pollen tubes Both FIM5 and PLIM2a/PLIM2b decorate shank-localized actin filaments FIM5 can inhibit the binding of PLIM2a and PLIM2b to actin filaments
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Affiliation(s)
- Ruihui Zhang
- 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
| | - Meng Zhang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yuxiang Jiang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Anbang Dai
- Ministry of Education Key Laboratory of Protein Sciences, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Wanying Zhao
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Dai Cao
- School of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Yaxian Lan
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Rong Yu
- School of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Hongwei Wang
- Ministry of Education Key Laboratory of Protein Sciences, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural 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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30
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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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31
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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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32
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Zheng YY, Lin XJ, Liang HM, Wang FF, Chen LY. The Long Journey of Pollen Tube in the Pistil. Int J Mol Sci 2018; 19:E3529. [PMID: 30423936 PMCID: PMC6275014 DOI: 10.3390/ijms19113529] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Revised: 11/04/2018] [Accepted: 11/07/2018] [Indexed: 12/17/2022] Open
Abstract
In non-cleistogamous plants, the male gametophyte, the pollen grain is immotile and exploits various agents, such as pollinators, wind, and even water, to arrive to a receptive stigma. The complex process of pollination involves a tubular structure, i.e., the pollen tube, which delivers the two sperm cells to the female gametophyte to enable double fertilization. The pollen tube has to penetrate the stigma, grow in the style tissues, pass through the septum, grow along the funiculus, and navigate to the micropyle of the ovule. It is a long journey for the pollen tube and its two sperm cells before they meet the female gametophyte, and it requires very accurate regulation to perform successful fertilization. In this review, we update the knowledge of molecular dialogues of pollen-pistil interaction, especially the progress of pollen tube activation and guidance, and give perspectives for future research.
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Affiliation(s)
- Yang-Yang Zheng
- Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Center for Genomics and Biotechnology, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Xian-Ju Lin
- Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Center for Genomics and Biotechnology, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Hui-Min Liang
- Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Center for Genomics and Biotechnology, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Fang-Fei Wang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Li-Yu Chen
- Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Center for Genomics and Biotechnology, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
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33
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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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Diao M, Qu X, Huang S. Calcium imaging in Arabidopsis pollen cells using G-CaMP5. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2018; 60:897-906. [PMID: 29424471 DOI: 10.1111/jipb.12642] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 02/07/2018] [Indexed: 05/18/2023]
Abstract
Calcium (Ca2+ ) signaling has been implicated in pollen germination and pollen tube growth. To date, however, we still know very little about how exactly Ca2+ signaling links to various physiological subcellular processes during pollen germination and pollen tube growth. Given that Ca2+ signaling is tightly related to the cytosolic concentration and dynamics of Ca2+ , it is vital to trace the dynamic changes in Ca2+ levels in order to decode Ca2+ signaling. Here, we demonstrate that G-CaMP5 serves well as an indicator for monitoring cytosolic Ca2+ dynamics in pollen cells. Using this probe, we show that cytosolic Ca2+ changes dramatically during pollen germination, and, as reported previously, Ca2+ forms a tip-focused gradient in the pollen tube and undergoes oscillation in the tip region during pollen tube growth. In particular, using G-CaMP5 allowed us to capture the dynamic changes in the cytosolic Ca2+ concentration ([Ca2+ ]cyt ) in pollen tubes in response to various exogenous treatments. Our data suggest that G-CaMP5 is a suitable probe for monitoring the dynamics of [Ca2+ ]cyt in pollen cells.
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Affiliation(s)
- Min Diao
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiaolu Qu
- 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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35
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Ding X, Zhang S, Liu J, Liu S, Su H. Arabidopsis FIM4 and FIM5 regulates the growth of root hairs in an auxin-insensitive way. PLANT SIGNALING & BEHAVIOR 2018; 13:e1473667. [PMID: 30148414 PMCID: PMC6204792 DOI: 10.1080/15592324.2018.1473667] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 04/27/2018] [Indexed: 06/08/2023]
Abstract
Tip-growing cells provide a useful model system for studying the underlying mechanisms of plant cell growth. The apical growth of root hairs is dependent on the microfilament skeleton, and auxin is an important regulator of root hair development. We functionally characterized actin bundling proteins AtFIM4 and AtFIM5, which were preferentially expressed in tip-growing cells such as pollen tubes and root hairs. The morphology and length of root hairs in atfim4/atfim5 double mutant line had obvious defects. In addition, we found the growth of root hairs of atfim4/atfim5 double mutant was insensitive to exogenous IAA (indole-3-acetic acid) treatment. So we consider that AtFIM4 and AtFIM5 act together to regulate the growth of root hair in an auxin-insensitive way.
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Affiliation(s)
- X. Ding
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, School of Life Sciences, Northwest University, Xi’an, China
| | - S. Zhang
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, School of Life Sciences, Northwest University, Xi’an, China
| | - J. Liu
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, School of Life Sciences, Northwest University, Xi’an, China
| | - S. Liu
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, School of Life Sciences, Northwest University, Xi’an, China
| | - H. Su
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, School of Life Sciences, Northwest University, Xi’an, China
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36
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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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37
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Miears HL, Gruber DR, Horvath NM, Antos JM, Young J, Sigurjonsson JP, Klem ML, Rosenkranz EA, Okon M, McKnight CJ, Vugmeyster L, Smirnov SL. Plant Villin Headpiece Domain Demonstrates a Novel Surface Charge Pattern and High Affinity for F-Actin. Biochemistry 2018; 57:1690-1701. [PMID: 29444403 DOI: 10.1021/acs.biochem.7b00856] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Plants utilize multiple isoforms of villin, an F-actin regulating protein with an N-terminal gelsolin-like core and a distinct C-terminal headpiece domain. Unlike their vertebrate homologues, plant villins have a much longer linker polypeptide connecting the core and headpiece. Moreover, the linker-headpiece connection region in plant villins lacks sequence homology to the vertebrate villin sequences. It is unknown to what extent the plant villin headpiece structure and function resemble those of the well-studied vertebrate counterparts. Here we present the first solution NMR structure and backbone dynamics characterization of a headpiece from plants, villin isoform 4 from Arabidopsis thaliana. The villin 4 headpiece is a 63-residue domain (V4HP63) that adopts a typical headpiece fold with an aromatics core and a tryptophan-centered hydrophobic cap within its C-terminal subdomain. However, V4HP63 has a distinct N-terminal subdomain fold as well as a novel, high mobility loop due to the insertion of serine residue in the canonical sequence that follows the variable length loop in headpiece sequences. The domain binds actin filaments with micromolar affinity, like the vertebrate analogues. However, the V4HP63 surface charge pattern is novel and lacks certain features previously thought necessary for high-affinity F-actin binding. Utilizing the updated criteria for strong F-actin binding, we predict that the headpiece domains of all other villin isoforms in A. thaliana have high affinity for F-actin.
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Affiliation(s)
- Heather L Miears
- Department of Chemistry , Western Washington University , 516 High Street , Bellingham , Washington 98225-9150 , United States
| | - David R Gruber
- Department of Chemistry , Western Washington University , 516 High Street , Bellingham , Washington 98225-9150 , United States
| | - Nicholas M Horvath
- Department of Chemistry , Western Washington University , 516 High Street , Bellingham , Washington 98225-9150 , United States
| | - John M Antos
- Department of Chemistry , Western Washington University , 516 High Street , Bellingham , Washington 98225-9150 , United States
| | - Jeff Young
- Department of Biology , Western Washington University , 516 High Street , Bellingham , Washington 98225-9160 , United States
| | - Johann P Sigurjonsson
- Department of Chemistry , Western Washington University , 516 High Street , Bellingham , Washington 98225-9150 , United States
| | - Maya L Klem
- Department of Chemistry , Western Washington University , 516 High Street , Bellingham , Washington 98225-9150 , United States
| | - Erin A Rosenkranz
- Department of Chemistry , Western Washington University , 516 High Street , Bellingham , Washington 98225-9150 , United States
| | - Mark Okon
- Department of Biochemistry and Molecular Biology, Department of Chemistry, and Michael Smith Laboratories , University of British Columbia , Vancouver , British Columbia V6T 1Z3 , Canada
| | - C James McKnight
- Department of Physiology and Biophysics , Boston University School of Medicine , 700 Albany Street , Boston , Massachusetts 02118-2526 , United States
| | - Liliya Vugmeyster
- Department of Chemistry , University of Colorado at Denver , Denver , Colorado 80204 , United States
| | - Serge L Smirnov
- Department of Chemistry , Western Washington University , 516 High Street , Bellingham , Washington 98225-9150 , United States
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38
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Mondal HA, Louis J, Archer L, Patel M, Nalam VJ, Sarowar S, Sivapalan V, Root DD, Shah J. Arabidopsis ACTIN-DEPOLYMERIZING FACTOR3 Is Required for Controlling Aphid Feeding from the Phloem. PLANT PHYSIOLOGY 2018; 176:879-890. [PMID: 29133373 PMCID: PMC5761796 DOI: 10.1104/pp.17.01438] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Accepted: 11/09/2017] [Indexed: 05/09/2023]
Abstract
The actin cytoskeleton network has an important role in plant cell growth, division, and stress response. Actin-depolymerizing factors (ADFs) are a group of actin-binding proteins that contribute to reorganization of the actin network. Here, we show that the Arabidopsis (Arabidopsis thaliana) ADF3 is required in the phloem for controlling infestation by Myzus persicae Sülzer, commonly known as the green peach aphid (GPA), which is an important phloem sap-consuming pest of more than fifty plant families. In agreement with a role for the actin-depolymerizing function of ADF3 in defense against the GPA, we show that resistance in adf3 was restored by overexpression of the related ADF4 and the actin cytoskeleton destabilizers, cytochalasin D and latrunculin B. Electrical monitoring of the GPA feeding behavior indicates that the GPA stylets found sieve elements faster when feeding on the adf3 mutant compared to the wild-type plant. In addition, once they found the sieve elements, the GPA fed for a more prolonged period from sieve elements of adf3 compared to the wild-type plant. The longer feeding period correlated with an increase in fecundity and population size of the GPA and a parallel reduction in callose deposition in the adf3 mutant. The adf3-conferred susceptibility to GPA was overcome by expression of the ADF3 coding sequence from the phloem-specific SUC2 promoter, thus confirming the importance of ADF3 function in the phloem. We further demonstrate that the ADF3-dependent defense mechanism is linked to the transcriptional up-regulation of PHYTOALEXIN-DEFICIENT4, which is an important regulator of defenses against the GPA.
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Affiliation(s)
- Hossain A Mondal
- Department of Biological Sciences, University of North Texas, Denton, Texas 76203
- Uttar Banga Krishi Viswavidyalaya, Pundibari, Cooch Behar 736165, India
| | - Joe Louis
- Department of Biological Sciences, University of North Texas, Denton, Texas 76203
- Department of Entomology and Department of Biochemistry, University of Nebraska, Lincoln, Nebraska 68583
| | - Lani Archer
- Department of Biological Sciences, University of North Texas, Denton, Texas 76203
- BioDiscovery Institute, University of North Texas, Denton, Texas 76203
| | - Monika Patel
- Department of Biological Sciences, University of North Texas, Denton, Texas 76203
- BioDiscovery Institute, University of North Texas, Denton, Texas 76203
| | - Vamsi J Nalam
- Department of Biological Sciences, University of North Texas, Denton, Texas 76203
- Department of Biology, Indiana University-Purdue University, Fort Wayne, Indiana 46805
| | - Sujon Sarowar
- Department of Biological Sciences, University of North Texas, Denton, Texas 76203
| | - Vishala Sivapalan
- Department of Biological Sciences, University of North Texas, Denton, Texas 76203
| | - Douglas D Root
- Department of Biological Sciences, University of North Texas, Denton, Texas 76203
| | - Jyoti Shah
- Department of Biological Sciences, University of North Texas, Denton, Texas 76203
- BioDiscovery Institute, University of North Texas, Denton, Texas 76203
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39
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Jia H, Yang J, Liesche J, Liu X, Hu Y, Si W, Guo J, Li J. Ethylene promotes pollen tube growth by affecting actin filament organization via the cGMP-dependent pathway in Arabidopsis thaliana. PROTOPLASMA 2018; 255:273-284. [PMID: 28864968 DOI: 10.1007/s00709-017-1158-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 08/23/2017] [Indexed: 06/07/2023]
Abstract
Ethylene and cGMP are key regulators of plant developmental processes. In this study, we demonstrate that ethylene or cGMP promote pollen tube growth in a dose-dependent manner. The etr1-1 mutant was found to be insensitive to ethylene with regard to pollen tube growth, while the growth-promoting effect of ethylene in etr2-2, ein4-4, or ein4-7 did not change, suggesting that ethylene signaling was mainly perceived by ETR1. However, the function of cGMP was not inhibited in etr1-1 and pollen tubes became insensitive to ethylene when the endogenous cGMP level was artificially decreased. This shows that cGMP is necessary for the control of pollen tube growth and that it might be a downstream component of ETR1 in the ethylene signaling pathway. Our study also found that ethylene or cGMP increase the actin bundles and elevated the percentage of relative amount of F-actin, while removal of cGMP decreased actin bundles abundance and altered the ratio of F-actin in the tip and base regions of pollen tubes. In conclusion, our data suggests that ethylene functions as the upstream signal of cGMP, and that both signals promote pollen germination and tube growth by regulating F-actin, which is essential for vesicular transport and cytoplasmic streaming.
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Affiliation(s)
- Honglei Jia
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China
- School of Environmental Science and Engineering, Shaanxi University of Science & Technology, Xi'an, Shaanxi, 710021, China
| | - Jun Yang
- School of Environmental Science and Engineering, Shaanxi University of Science & Technology, Xi'an, Shaanxi, 710021, China
| | - Johannes Liesche
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Xin Liu
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Yanfeng Hu
- Key Laboratory of Mollisols Agroecology, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Nangang District, Harbin, 150000, China
| | - Wantong Si
- Inner Mongolia Key Laboratory of Biomass-Energy Conversion, Inner Mongolia University of Science and Technology, Neimenggu, Baotou, 014010, China
| | - Junkang Guo
- School of Environmental Science and Engineering, Shaanxi University of Science & Technology, Xi'an, Shaanxi, 710021, China
| | - Jisheng Li
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China.
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40
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Paez-Garcia A, Sparks JA, de Bang L, Blancaflor EB. Plant Actin Cytoskeleton: New Functions from Old Scaffold. PLANT CELL MONOGRAPHS 2018. [DOI: 10.1007/978-3-319-69944-8_6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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41
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Szymanski D, Staiger CJ. The Actin Cytoskeleton: Functional Arrays for Cytoplasmic Organization and Cell Shape Control. PLANT PHYSIOLOGY 2018; 176:106-118. [PMID: 29192029 PMCID: PMC5761824 DOI: 10.1104/pp.17.01519] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 11/29/2017] [Indexed: 05/18/2023]
Abstract
Functionally distinct actin filament arrays cluster organelles and define cellular scale flow patterns for secretion.
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Affiliation(s)
- Dan Szymanski
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907
- Department of Agronomy, Purdue University, West Lafayette, Indiana 47907
| | - Christopher J Staiger
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907
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42
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Su H, Feng H, Chao X, Ding X, Nan Q, Wen C, Liu H, Xiang Y, Liu W. Fimbrins 4 and 5 Act Synergistically During Polarized Pollen Tube Growth to Ensure Fertility in Arabidopsis. PLANT & CELL PHYSIOLOGY 2017; 58:2006-2016. [PMID: 29036437 DOI: 10.1093/pcp/pcx138] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2017] [Accepted: 09/03/2017] [Indexed: 06/07/2023]
Abstract
The germination and polar growth of pollen are prerequisite for double fertilization in plants. The actin cytoskeleton and its binding proteins play pivotal roles in pollen germination and pollen tube growth. Two homologs of the actin-bundling protein fimbrin, AtFIM4 and AtFIM5, are highly expressed in pollen in Arabidopsis and can form distinct actin architectures in vitro, but how they co-operatively regulate pollen germination and pollen tube growth in vivo is largely unknown. In this study, we explored their functions during pollen germination and polar growth. Histochemical analysis demonstrated that AtFIM4 was expressed only after pollen grain hydration and, in the early stage of pollen tube growth, the expression level of AtFIM4 was low, indicating that it functions mainly during polarized tube growth, whereas AtFIM5 had high expression levels in both pollen grains and pollen tubes. Atfim4/atfim5 double mutant plants had fertility defects including reduced silique length and seed number, which were caused by severe defects in pollen germination and pollen tube growth. When the atfim4/atfim5 double mutant was complemented with the AtFIM5 protein, the polar growth of pollen tubes was fully rescued; however, AtFIM4 could only partially restore these defects. Fluorescence labeling showed that loss of function of both AtFIM4 and AtFIM5 decreased the extent of actin filament bundling throughout pollen tubes. Collectively, our results revealed that AtFIM4 acts co-ordinately with AtFIM5 to organize and maintain normal actin architecture in pollen grains and pollen tubes to fulfill double fertilization in plants.
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Affiliation(s)
- Hui Su
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, School of Life Sciences, Northwest University, Xi'an 710069, China
| | - Hualing Feng
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, School of Life Sciences, Northwest University, Xi'an 710069, China
| | - Xiaoting Chao
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, School of Life Sciences, Northwest University, Xi'an 710069, China
| | - Xia Ding
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, School of Life Sciences, Northwest University, Xi'an 710069, China
| | - Qiong Nan
- Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Chenxi Wen
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, School of Life Sciences, Northwest University, Xi'an 710069, China
| | | | - Yun Xiang
- Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Wenzhe Liu
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, School of Life Sciences, Northwest University, Xi'an 710069, China
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43
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Chang M, Li Z, Huang S. Monomeric G-actin is uniformly distributed in pollen tubes and is rapidly redistributed via cytoplasmic streaming during pollen tube growth. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2017; 92:509-519. [PMID: 28845534 DOI: 10.1111/tpj.13668] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2017] [Revised: 08/11/2017] [Accepted: 08/18/2017] [Indexed: 05/25/2023]
Abstract
Dynamic assembly and disassembly of the actin cytoskeleton has been implicated in the regulation of pollen germination and subsequent tube growth. It is widely accepted that actin filaments are arrayed into distinct structures within different regions of the pollen tube. Maintenance of the equilibrium between monomeric globular actin (G-actin) and filamentous actin (F-actin) is crucial for actin assembly and array construction, and the local concentration of G-actin thus directly impacts actin assembly. The localization and dynamics of G-actin in the pollen tube, however, remain to be determined conclusively. To address this question, we created a series of fusion proteins between green fluorescent protein (GFP) and the Arabidopsis reproductive actin ACT11. Expression of a fusion protein with GFP inserted after methionine at position 49 within the DNase I-binding loop of ACT11 (GFPMet49 -ACT11) rescued the phenotypes in act11 mutants. Consistent with the notion that the majority of actin is in its monomeric form, GFPMet49 -ACT11 and GFP fusion proteins of four other reproductive actins generated with the same strategy do not obviously label filamentous structures. In further support of the functionality of these fusion proteins, we found that they can be incorporated into filamentous structures in jasplakinolide (Jasp)-treated pollen tubes. Careful observations showed that G-actin is distributed uniformly in the pollen tube and is rapidly redistributed via cytoplasmic streaming during pollen tube growth. Our study suggests that G-actin is readily available in the cytoplasm to support continuous actin polymerization during rapid pollen tube growth.
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Affiliation(s)
- Ming Chang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Zhankun Li
- 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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44
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Jiang Y, Wang J, Xie Y, Chen N, Huang S. ADF10 shapes the overall organization of apical actin filaments by promoting their turnover and ordering in pollen tubes. J Cell Sci 2017; 130:3988-4001. [PMID: 29061882 DOI: 10.1242/jcs.207738] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2017] [Accepted: 10/09/2017] [Indexed: 12/26/2022] Open
Abstract
Here, we show that Arabidopsis ADF10 plays an important role in shaping the overall organization of apical actin filaments by promoting their turnover and ordering. ADF10 severs and depolymerizes actin filaments in vitro and is distributed throughout the entire pollen tube. In adf10 mutants, severing and monomer dissociation events for apical actin filaments are reduced, and the apical actin structure extends further toward the tube base than in wild-type tubes. In particular, the percentage of apical actin filaments that form large angles to the tube growth axis is much higher in adf10 pollen tubes, and the actin filaments are more randomly distributed, implying that ADF10 promotes their ordering. Consistent with the role of apical actin filaments in physically restricting the movement of vesicles, the region in which apical vesicles accumulate is enlarged at the tip of adf10 pollen tubes. Both tipward and backward movements of small vesicles are altered within the growth domain of adf10 pollen tubes. Thus, our study suggests that ADF10 shapes the organization of apical actin filaments to regulate vesicle trafficking and pollen tube growth.
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Affiliation(s)
- Yuxiang Jiang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Juan Wang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yurong Xie
- Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Naizhi Chen
- Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Shanjin Huang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
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45
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Zhu J, Nan Q, Qin T, Qian D, Mao T, Yuan S, Wu X, Niu Y, Bai Q, An L, Xiang Y. Higher-Ordered Actin Structures Remodeled by Arabidopsis ACTIN-DEPOLYMERIZING FACTOR5 Are Important for Pollen Germination and Pollen Tube Growth. MOLECULAR PLANT 2017; 10:1065-1081. [PMID: 28606871 DOI: 10.1016/j.molp.2017.06.001] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 06/02/2017] [Accepted: 06/05/2017] [Indexed: 06/07/2023]
Abstract
Dynamics of the actin cytoskeleton are essential for pollen germination and pollen tube growth. ACTIN-DEPOLYMERIZING FACTORs (ADFs) typically contribute to actin turnover by severing/depolymerizing actin filaments. Recently, we demonstrated that Arabidopsis subclass III ADFs (ADF5 and ADF9) evolved F-actin-bundling function from conserved F-actin-depolymerizing function. However, little is known about the physiological function, the evolutional significance, and the actin-bundling mechanism of these neofunctionalized ADFs. Here, we report that loss of ADF5 function caused delayed pollen germination, retarded pollen tube growth, and increased sensitive to latrunculin B (LatB) treatment by affecting the generation and maintenance of actin bundles. Examination of actin filament dynamics in living cells revealed that the bundling frequency was significantly decreased in adf5 pollen tubes, consistent with its biochemical functions. Further biochemical and genetic complementation analyses demonstrated that both the N- and C-terminal actin-binding domains of ADF5 are required for its physiological and biochemical functions. Interestingly, while both are atypical actin-bundling ADFs, ADF5, but not ADF9, plays an important role in mature pollen physiological activities. Taken together, our results suggest that ADF5 has evolved the function of bundling actin filaments and plays an important role in the formation, organization, and maintenance of actin bundles during pollen germination and pollen tube growth.
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Affiliation(s)
- Jingen Zhu
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Qiong Nan
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Tao Qin
- State Key Laboratory of Plant Physiology and Biochemistry, Department of Plant Sciences, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Dong Qian
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Tonglin Mao
- State Key Laboratory of Plant Physiology and Biochemistry, Department of Plant Sciences, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Shunjie Yuan
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Xiaorong Wu
- 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
| | - Qifeng Bai
- 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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46
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Zhang M, Han LB, Wang WY, Wu SJ, Jiao GL, Su L, Xia GX, Wang HY. Overexpression of GhFIM2 propels cotton fiber development by enhancing actin bundle formation. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2017; 59:531-534. [PMID: 28474404 DOI: 10.1111/jipb.12552] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 04/28/2017] [Indexed: 06/07/2023]
Abstract
Cell elongation and secondary wall deposition are two consecutive stages during cotton fiber development. The mechanisms controlling the progression of these two developmental phases remain largely unknown. Here, we report the functional characterization of the actin-bundling protein GhFIM2 in cotton fiber. Overexpression of GhFIM2 increased the abundance of actin bundles, which was accompanied with accelerated fiber growth at the fast-elongating stage. Meanwhile, overexpression of GhFIM2 could propel the onset of secondary cell wall biogenesis. These results indicate that the dynamic rearrangement of actin higher structures involving GhFIM2 plays an important role in the development of cotton fiber cells.
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Affiliation(s)
- Min Zhang
- Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
- State Key Laboratory of Plant Genomics, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Li-Bo Han
- Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
- State Key Laboratory of Plant Genomics, Beijing 100101, China
| | - Wen-Yan Wang
- Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
- State Key Laboratory of Plant Genomics, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shen-Jie Wu
- Institute of Cotton Research, Shanxi Academy of Agricultural Sciences, Yuncheng 044000, China
| | - Gai-Li Jiao
- Institute of Cotton Research, Shanxi Academy of Agricultural Sciences, Yuncheng 044000, China
| | - Lei Su
- Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
- State Key Laboratory of Plant Genomics, Beijing 100101, China
| | - Gui-Xian Xia
- Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
- State Key Laboratory of Plant Genomics, Beijing 100101, China
| | - Hai-Yun Wang
- Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
- State Key Laboratory of Plant Genomics, Beijing 100101, China
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47
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Qu X, Zhang R, Zhang M, Diao M, Xue Y, Huang S. Organizational Innovation of Apical Actin Filaments Drives Rapid Pollen Tube Growth and Turning. MOLECULAR PLANT 2017; 10:930-947. [PMID: 28502709 DOI: 10.1016/j.molp.2017.05.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 04/15/2017] [Accepted: 05/01/2017] [Indexed: 06/07/2023]
Abstract
Polarized tip growth is a fundamental cellular process in many eukaryotes. In this study, we examined the dynamic restructuring of the actin cytoskeleton and its relationship to vesicle transport during pollen tip growth in Arabidopsis. We found that actin filaments originating from the apical membrane form a specialized structure consisting of longitudinally aligned actin bundles at the cortex and inner cytoplasmic filaments with a distinct distribution. Using actin-based pharmacological treatments and genetic mutants in combination with FRAP (fluorescence recovery after photobleaching) technology to visualize the transport of vesicles within the growth domain of pollen tubes, we demonstrated that cortical actin filaments facilitate tip-ward vesicle transport. We also discovered that the inner apical actin filaments prevent backward movement of vesicles, thus ensuring that sufficient vesicles accumulate at the pollen tube tip to support the rapid growth of the pollen tube. The combinatorial effect of cortical and internal apical actin filaments perfectly explains the generation of the inverted "V" cone-shaped vesicle distribution pattern at the pollen tube tip. When pollen tubes turn, apical actin filaments at the facing side undergo depolymerization and repolymerization to reorient the apical actin structure toward the new growth direction. This actin restructuring precedes vesicle accumulation and changes in tube morphology. Thus, our study provides new insights into the functional relationship between actin dynamics and vesicle transport during rapid and directional pollen tube growth.
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Affiliation(s)
- Xiaolu Qu
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Ruihui Zhang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Meng Zhang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China; Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Min Diao
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China; Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Yongbiao Xue
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
| | - Shanjin Huang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China; Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
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48
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Abstract
The eukaryotic actin cytoskeleton is a highly dynamic framework that is involved in many biological processes, such as cell growth, division, morphology, and motility. G-actin polymerizes into microfilaments that associate into bundles, patches, and networks, which, in turn, organize into higher order structures that are fundamental for the course of important physiological events. Actin rings are an example for such higher order actin entities, but this term represents an actually diverse set of subcellular structures that are involved in various processes. This review especially sheds light on a crucial type of non-constricting ring-like actin networks, and categorizes them under the term 'actin fringe'. These 'actin fringes' are visualized as highly dynamic and yet steady structures in the tip of various polarized growing cells. The present comprehensive overview compares the actin fringe characteristics of rapidly elongating pollen tubes with several related actin arrays in other cell types of diverse species. The current state of knowledge about various actin fringe functions is summarized, and the key role of this structure in the polar growth process is discussed.
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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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49
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Li S, Dong H, Pei W, Liu C, Zhang S, Sun T, Xue X, Ren H. LlFH1-mediated interaction between actin fringe and exocytic vesicles is involved in pollen tube tip growth. THE NEW PHYTOLOGIST 2017; 214:745-761. [PMID: 28092406 DOI: 10.1111/nph.14395] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 11/16/2016] [Indexed: 05/15/2023]
Abstract
Pollen tube tip growth is an extreme form of polarized cell growth, which requires polarized exocytosis based on a dynamic actin cytoskeleton. However, the molecular basis for the connection between actin filaments and exocytic vesicles is unclear. Here, we identified a Lilium longiflorum pollen-specific formin (LlFH1) and found that it localized at the apical vesicles and plasma membrane (PM). Overexpression of LlFH1 induced excessive actin cables in the tube tip region, and downregulation of LlFH1 eliminated the actin fringe. Fluorescence recovery after photobleaching (FRAP) analysis revealed that LlFH1-labeled exocytic vesicles exhibited an initial accumulation at the shoulder of the apex and coincided with the leading edge of the actin fringe. Time-lapse analysis suggested that nascent actin filaments followed the emergence of the apical vesicles, implying that LlFH1 at apical vesicles could initiate actin polymerization. Biochemical assays showed that LlFH1 FH1FH2 could nucleate actin polymerization, but then capped the actin filament at the barbed end and inhibited its elongation. However, in the presence of lily profilins, LlFH1 FH1FH2 could accelerate barbed-end actin elongation. In addition, LlFH1 FH1FH2 was able to bundle actin filaments. Thus, we propose that LlFH1 and profilin coordinate the interaction between the actin fringe and exocytic vesicle trafficking during pollen tube growth of lily.
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Affiliation(s)
- Shanwei Li
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education and College of Life Science, Beijing Normal University, Beijing, 100875, China
| | - Huaijian Dong
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education and College of Life Science, Beijing Normal University, Beijing, 100875, China
| | - Weike Pei
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education and College of Life Science, Beijing Normal University, Beijing, 100875, China
| | - Chaonan Liu
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education and College of Life Science, Beijing Normal University, Beijing, 100875, China
| | - Sha Zhang
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education and College of Life Science, Beijing Normal University, Beijing, 100875, China
| | - Tiantian Sun
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education and College of Life Science, Beijing Normal University, Beijing, 100875, China
| | - Xiuhua Xue
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education and College of Life Science, Beijing Normal University, Beijing, 100875, China
| | - Haiyun Ren
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education and College of Life Science, Beijing Normal University, Beijing, 100875, China
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50
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Abstract
Underlying rapid and directional pollen tube growth is the active intracellular trafficking system that carries materials necessary for cell wall synthesis and membrane expansion to the expanding point of the pollen tube. The actin cytoskeleton has been shown to control various intracellular trafficking events in the pollen tube, but the underlying cellular and molecular mechanisms remain poorly understood. To better understand how the actin cytoskeleton is involved in the regulation of intracellular trafficking events, we need to establish assays to visualize and quantify the distribution and dynamics of organelles, vesicles, or secreted proteins. In this chapter, we introduce methods regarding the visualization and quantification of the distribution and dynamics of organelles or vesicles in pollen tubes.
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