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Li YK, Dai GY, Zhang YM, Yao N. Imaging Plant Lipids with Fluorescent Reporters. PLANTS (BASEL, SWITZERLAND) 2024; 14:15. [PMID: 39795280 PMCID: PMC11723198 DOI: 10.3390/plants14010015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2024] [Revised: 12/13/2024] [Accepted: 12/19/2024] [Indexed: 01/13/2025]
Abstract
In plants, lipids function as structural elements and signaling molecules. Understanding lipid composition and dynamics is essential for unraveling their biological functions and metabolism. Mapping the spatiotemporal distribution of lipids in plants holds great potential for elucidating lipid biosynthetic pathways and gaining insights to guide crop genetic engineering. Recent progress in fluorescence microscopy and imaging has opened new opportunities for researchers to visualize plant lipids in vivo at high spatiotemporal resolution. In this review, we provide an up-to-date overview of the methods used to image plant lipids with fluorescence microscopy. We highlight caveats and potential limitations of these approaches and provide suggestions for optimizing their utilization. This review synthesizes current knowledge and highlights the potential of these methods to provide new insights into lipid biology.
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Affiliation(s)
- Yong-Kang Li
- Guangdong Provincial Key Laboratory of Plant Stress Biology, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China; (Y.-K.L.); (Y.-M.Z.)
| | - Guang-Yi Dai
- South China National Botanical Garden, Chinese Academy of Sciences, Guangzhou 510275, China;
| | - Yu-Meng Zhang
- Guangdong Provincial Key Laboratory of Plant Stress Biology, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China; (Y.-K.L.); (Y.-M.Z.)
| | - Nan Yao
- Guangdong Provincial Key Laboratory of Plant Stress Biology, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China; (Y.-K.L.); (Y.-M.Z.)
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2
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Kong W, Duan P, Wang Y, Zhang T, Huang M, Kang J, Wang L, Wei B, Chang Y. Silencing CaPIP5K4-1 leads to decreased male fertility in Capsicum annuum L. PLANTA 2024; 261:7. [PMID: 39630306 DOI: 10.1007/s00425-024-04584-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2024] [Accepted: 11/26/2024] [Indexed: 01/16/2025]
Abstract
MAIN CONCLUSION Phosphatidylinositol 4-phosphate 5-kinase gene CaPIP5K4-1 is highly expressed in the pepper anthers. Virus-induced gene silencing of CaPIP5K4-1 leads to reduced male fertility in pepper. The phosphatidylinositol 4-phosphate 5-kinase (PIP5K) is a pivotal enzyme in the phosphatidylinositol signaling pathway, and its crucial involvement in both plant development and stress response has been established. Here, we found that the expression of CaPIP5K4-1 in pepper was significantly higher in the fertile flower buds compared to sterile flower buds. Furthermore, its expression was validated in anthers and pollens by qRT-PCR and RNA-ISH assays, respectively. Its GFP fusion protein was mainly located on the plasma membrane. Silencing CaPIP5K4-1 in fertile pepper accessions resulted in wrinkled pollen grain cell walls, decreased pollen germination efficiency, and inhibited pollen tube growth. The transcription levels of multiple genes in the phosphatidylinositol signaling pathway were also assessed. Five phospholipase C (PLC) genes were downregulated in silenced plants. On the contrary, inositol phosphatase SAC and phosphatase and tensin homolog (PTEN) were upregulated. This study reported the role of CaPIP5K4-1 in pepper male fertility and provided insights into the regulatory mechanisms of PI signaling in pepper.
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Affiliation(s)
- Weifu Kong
- College of Horticulture, Gansu Agricultural University, Lanzhou, 730030, China
| | - Panpan Duan
- Vegetable Institute, Gansu Academy of Agricultural Sciences, Lanzhou, 730070, Gansu, China
| | - Yuhang Wang
- College of Horticulture, Gansu Agricultural University, Lanzhou, 730030, China
| | - Tao Zhang
- College of Horticulture, Gansu Agricultural University, Lanzhou, 730030, China
| | - Mianzhu Huang
- College of Horticulture, Gansu Agricultural University, Lanzhou, 730030, China
| | - Jingtao Kang
- College of Horticulture, Gansu Agricultural University, Lanzhou, 730030, China
| | - Lina Wang
- College of Horticulture, Gansu Agricultural University, Lanzhou, 730030, China
| | - Bingqiang Wei
- College of Horticulture, Gansu Agricultural University, Lanzhou, 730030, China.
| | - Yajun Chang
- Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing Botanical Garden, Mem. Sun Yat-Sen, Nanjing, 210014, China.
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3
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Ruan H, Wang T, Ren H, Zhang Y. AtFH5-labeled secretory vesicles-dependent calcium oscillation drives exocytosis and stepwise bulge during pollen germination. Cell Rep 2023; 42:113319. [PMID: 37897722 DOI: 10.1016/j.celrep.2023.113319] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2023] [Revised: 09/11/2023] [Accepted: 10/06/2023] [Indexed: 10/30/2023] Open
Abstract
Pollen germination is an essential step for delivering sperm cells to the embryo sac for double fertilization in flowering plants. The cytosolic Ca2+ concentration ([Ca2+]cyt) and vesicle dynamics are critical for pollen germination, but their potential correlation in pollen grains is not fully understood. Here, we report that [Ca2+]cyt oscillates periodically at the prospective germination sites during pollen germination. The [Ca2+]cyt is mainly from extracellular Ca2+ ([Ca2+]ext) influx, which implicates the Ca2+-permeable ion channel cyclic nucleotide-gated channel 18 (CNGC18). The [Ca2+]cyt oscillations spatiotemporally correlate with the accumulation of secretory vesicles labeled by a formin protein AtFH5, and disruption of vesicle accumulation inhibits the [Ca2+]cyt oscillations. In turn, the [Ca2+]cyt oscillations promote exocytosis, which leads to stepwise cell extension during pollen germination. Together, these data provide a timeline of vesicle dynamics, calcium oscillation, and exocytosis during pollen germination and highlight the importance of the correlation of these events for pollen germination.
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Affiliation(s)
- Huaqiang Ruan
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education, College of Life Science, Beijing Normal University, Beijing 100875, China; Center for Biological Science and Technology, Zhuhai-Macao Biotechnology Joint Laboratory, Advanced Institute of Natural Science, Beijing Normal University, Zhuhai 519087, China
| | - Ting Wang
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education, College of Life Science, Beijing Normal University, Beijing 100875, China
| | - Haiyun Ren
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education, College of Life Science, Beijing Normal University, Beijing 100875, China; Center for Biological Science and Technology, Zhuhai-Macao Biotechnology Joint Laboratory, Advanced Institute of Natural Science, Beijing Normal University, Zhuhai 519087, China.
| | - Yi Zhang
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education, College of Life Science, Beijing Normal University, Beijing 100875, China.
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4
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Weng X, Shen Y, Jiang L, Zhao L, Wang H. Spatiotemporal organization and correlation of tip-focused exocytosis and endocytosis in regulating pollen tube tip growth. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2023; 330:111633. [PMID: 36775070 DOI: 10.1016/j.plantsci.2023.111633] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 01/09/2023] [Accepted: 02/07/2023] [Indexed: 06/18/2023]
Abstract
Pollen tube polar growth is a key cellular process during plant fertilization and is regulated by tip-focused exocytosis and endocytosis. However, the spatiotemporal dynamics and localizations of apical exocytosis and endocytosis in the tip region are still a matter of debate. Here, we use a refined spinning-disk confocal microscope coupled with fluorescence recovery after photobleaching for sustained live imaging and quantitative analysis of rapid vesicular activities in growing pollen tube tips. We traced and analyzed the occurrence site of exocytic plasma membrane-targeting of Arabidopsis secretory carrier membrane protein 4 and its subsequent endocytosis in tobacco pollen tube tips. We demonstrated that the pollen tube apex is the site for both vesicle polar exocytic fusion and endocytosis to take place. In addition, we disrupted either tip-focused exocytosis or endocytosis and found that their dynamic activities are closely correlated with one another basing on the spatial organization of actin fringe. Collectively, our findings attempt to propose a new exocytosis and endocytosis-coordinated yin-yang working model underlying the apical membrane organization and dynamics during pollen tube tip growth.
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Affiliation(s)
- Xun Weng
- College of Life Sciences, South China Agricultural University, Guangzhou 510642, China
| | - Yifan Shen
- Utahloy International School of Guangzhou, Guangzhou 510642, China
| | - Liwen Jiang
- School of Life Sciences, Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China; Institute of Plant Molecular Biology & Agricultural Biotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - Lifeng Zhao
- College of Life Sciences, South China Agricultural University, Guangzhou 510642, China.
| | - Hao Wang
- College of Life Sciences, South China Agricultural University, Guangzhou 510642, China.
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5
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Hormonal Signaling in the Progamic Phase of Fertilization in Plants. HORTICULTURAE 2022. [DOI: 10.3390/horticulturae8050365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Pollen–pistil interaction is a basic process in the reproductive biology of flowering plants and has been the subject of intense fundamental research that has a pronounced practical value. The phytohormones ethylene (ET) and cytokinin (CK) together with other hormones such as auxin, gibberellin (GA), jasmonic acid (JA), abscisic acid (ABA), and brassinosteroids (BRs) influence different stages of plant development and growth. Here, we mainly focus on the information about the ET and CK signaling in the progamic phase of fertilization. This signaling occurs during male gametophyte development, including tapetum (TAP) cell death, and pollen tube growth, including synergid programmed cell death (PCD) and self-incompatibility (SI)-induced PCD. ET joins the coordination of successive events in the developing anther, including the TAP development and cell death, anther dehiscence, microspore development, pollen grain maturation, and dehydration. Both ET and CK take part in the regulation of E. ET signaling accompanies adhesion, hydration, and germination of pollen grains in the stigma and growth of pollen tubes in style tissues. Thus, ET production may be implicated in the pollination signaling between organs accumulated in the stigma and transmitted to the style and ovary to ensure successful pollination. Some data suggest that ET and CK signaling are involved in S-RNase-based SI.
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6
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P2K1 Receptor, Heterotrimeric Gα Protein and CNGC2/4 Are Involved in Extracellular ATP-Promoted Ion Influx in the Pollen of Arabidopsis thaliana. PLANTS 2021; 10:plants10081743. [PMID: 34451790 PMCID: PMC8400636 DOI: 10.3390/plants10081743] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 08/20/2021] [Accepted: 08/20/2021] [Indexed: 11/17/2022]
Abstract
As an apoplastic signal, extracellular ATP (eATP) is involved in plant growth and development. eATP promotes tobacco pollen germination (PG) and pollen tube growth (PTG) by stimulating Ca2+ or K+ absorption. Nevertheless, the mechanisms underlying eATP-stimulated ion uptake and their role in PG and PTG are still unclear. Here, ATP addition was found to modulate PG and PTG in 34 plant species and showed a promoting effect in most of these species. Furthermore, by using Arabidopsis thaliana as a model, the role of several signaling components involved in eATP-promoted ion (Ca2+, K+) uptake, PG, and PTG were investigated. ATP stimulated while apyrase inhibited PG and PTG. Patch-clamping results showed that ATP promoted K+ and Ca2+ influx into pollen protoplasts. In loss-of-function mutants of P2K1 (dorn1-1 and dorn1-3), heterotrimeric G protein α subunit (gpa1-1, gpa1-2), or cyclic nucleotide gated ion channel (cngc2, cngc4), eATP-stimulated PG, PTG, and ion influx were all impaired. Our results suggest that these signaling components may be involved in eATP-promoted PG and PTG by regulating Ca2+ or K+ influx in Arabidopsis pollen grains.
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7
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Abstract
The gametophyte represents the sexual phase in the alternation of generations in plants; the other, nonsexual phase is the sporophyte. Here, we review the evolutionary origins of the male gametophyte among land plants and, in particular, its ontogenesis in flowering plants. The highly reduced male gametophyte of angiosperm plants is a two- or three-celled pollen grain. Its task is the production of two male gametes and their transport to the female gametophyte, the embryo sac, where double fertilization takes place. We describe two phases of pollen ontogenesis-a developmental phase leading to the differentiation of the male germline and the formation of a mature pollen grain and a functional phase representing the pollen tube growth, beginning with the landing of the pollen grain on the stigma and ending with double fertilization. We highlight recent advances in the complex regulatory mechanisms involved, including posttranscriptional regulation and transcript storage, intracellular metabolic signaling, pollen cell wall structure and synthesis, protein secretion, and phased cell-cell communication within the reproductive tissues.
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Affiliation(s)
- Said Hafidh
- Laboratory of Pollen Biology, Institute of Experimental Botany of the Czech Academy of Sciences, 165 02 Prague 6, Czech Republic; ,
| | - David Honys
- Laboratory of Pollen Biology, Institute of Experimental Botany of the Czech Academy of Sciences, 165 02 Prague 6, Czech Republic; ,
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8
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Surso MV, Chuhchin DG, Khviyuzov SS, Pokryishkin SA. Mechanism of Pollen Germination and Pollen Tubes’ Growth in Common Juniper (Juniper communis L.) In Vitro. Russ J Dev Biol 2020. [DOI: 10.1134/s1062360420050070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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9
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Qian M, Xu L, Tang C, Zhang H, Gao H, Cao P, Yin H, Wu L, Wu J, Gu C, Zhang S. PbrPOE21 inhibits pear pollen tube growth in vitro by altering apical reactive oxygen species content. PLANTA 2020; 252:43. [PMID: 32870426 DOI: 10.1007/s00425-020-03446-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Accepted: 08/21/2020] [Indexed: 06/11/2023]
Abstract
Genome-wide identification, tissue-specific expression analysis and functional characterization of selected genes containing the pear Pollen Olea europaea I domain reveal their roles in pollen tube growth. Genes containing the Pollen Olea europaea I (POE) domain play crucial roles in diverse growth and developmental processes. Nevertheless, the specific functions of POE family members in progression of pollen tube growth (PTG) remain uncharacterized. We identified 45 PbrPOE genes in the pear (Pyrus bretschneideri) genome, clustered into seven subclasses. PbrPOE genes contained 1 to 11 exons and 0 to 10 introns, with exon/intron structure mostly conserved within each subclass. Whole-genome duplication has mainly contributed to the duplication pattern of PbrPOE genes in pear. Expression profiles of 45 PbrPOE genes in 12 different pear tissues revealed that six PbrPOE genes (PbrPOE6, 12, 21, 29, 35 and 41) of subclass B were highly expressed during the growth of the pear pollen tube in vitro. PbrPOE21 was selected for further functional analysis on the basis of its high and differential expression pattern in pollen. Antisense oligodeoxynucleotide assays demonstrated that PTG was augmented in vitro when PbrPOE21 expression was significantly inhibited. Moreover, pollen tube length in vitro was reduced when PbrPOE21 was transitorily over-expressed using particle bombardment technology. Exogenous PbrPOE21 recombinant protein inhibited PTG in vitro at an optimum concentration of 1.8 µM. PbrPOE21 also affected reactive oxygen species content in the pear pollen tube apex. We suggest that PbrPOE21 inhibits PTG in vitro by altering apical reactive oxygen species content.
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Affiliation(s)
- Ming Qian
- College of Horticulture, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China
| | - Linlin Xu
- College of Horticulture, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China
| | - Chao Tang
- College of Horticulture, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China
| | - Hao Zhang
- College of Horticulture, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China
| | - Hongru Gao
- College of Horticulture, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China
| | - Peng Cao
- College of Horticulture, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China
| | - Hao Yin
- College of Horticulture, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China
| | - Lei Wu
- College of Horticulture, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China
| | - Juyou Wu
- College of Horticulture, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China
| | - Chao Gu
- College of Horticulture, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China
| | - Shaoling Zhang
- College of Horticulture, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China.
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10
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Potocký M, Bezvoda R, Pejchar P. Antisense Oligodeoxynucleotide-Mediated Gene Knockdown in Pollen Tubes. Methods Mol Biol 2019; 1992:359-365. [PMID: 31148051 DOI: 10.1007/978-1-4939-9469-4_24] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Specific gene knockdown mediated by the antisense oligodeoxynucleotides (AODNs) strategy emerged as a rapid and effective tool for probing gene role in plant cells, particularly tip-growing pollen tubes. Here, we describe the protocol for the successful employment of AODN technique in growing tobacco pollen tubes, covering AODN design, application, and analysis of the results. We also discuss the advantages and drawbacks of this method.
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Affiliation(s)
- Martin Potocký
- Institute of Experimental Botany, Czech Academy of Sciences, Prague, Czech Republic.
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czech Republic.
| | - Radek Bezvoda
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Přemysl Pejchar
- Institute of Experimental Botany, Czech Academy of Sciences, Prague, Czech Republic
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czech Republic
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11
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Sankaranarayanan S, Higashiyama T. Capacitation in Plant and Animal Fertilization. TRENDS IN PLANT SCIENCE 2018; 23:129-139. [PMID: 29170007 DOI: 10.1016/j.tplants.2017.10.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 10/21/2017] [Accepted: 10/31/2017] [Indexed: 06/07/2023]
Abstract
Sexual reproduction relies on the successful fusion of the sperm and egg cell. Despite the vast differences between plants and animals, there are similarities at a molecular level between plant and animal reproduction. While the molecular basis of fertilization has been extensively studied in plants, the process of capacitation has received little attention until recently. Recent research has started to uncover the molecular basis of plant capacitation. Furthermore, recent studies suggest that the key molecules in plants and animal fertilization are functionally conserved. Here, we review new insights for our understanding of capacitation of pollen tube and fertilization in plants and also propose that there are commonalities in the process of sexual reproduction between plants and animals.
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Affiliation(s)
- Subramanian Sankaranarayanan
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan.
| | - Tetsuya Higashiyama
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan; Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan.
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12
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Lamport DTA, Tan L, Held MA, Kieliszewski MJ. Pollen tube growth and guidance: Occam's razor sharpened on a molecular arabinogalactan glycoprotein Rosetta Stone. THE NEW PHYTOLOGIST 2018; 217:491-500. [PMID: 28990197 DOI: 10.1111/nph.14845] [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] [Indexed: 05/21/2023]
Abstract
Occam's Razor suggests a new model of pollen tube tip growth based on a novel Hechtian oscillator that integrates a periplasmic arabinogalactan glycoprotein-calcium (AGP-Ca2+ ) capacitor with tip-localized AGPs as the source of tip-focussed cytosolic Ca2+ oscillations: Hechtian adhesion between the plasma membrane and the cell wall of the growing tip acts as a piconewton force transducer that couples the internal stress of a rapidly growing wall to the plasma membrane. Such Hechtian transduction opens stretch-activated Ca2+ channels and activates H+ -ATPase proton pump efflux that dissociates periplasmic AGP-Ca2+ resulting in a Ca2+ influx that activates exocytosis of wall precursors. Thus, a highly simplified pectic primary cell wall regulates its own synthesis by a Hechtian growth oscillator that regulates overall tip growth. By analogy with the three cryptic inscriptions of the classical Rosetta Stone, the Hechtian Hypothesis translates classical AGP function as a Ca2+ capacitor, pollen tube guide and wall plasticizer into a simple but widely applicable model of tip growth. Even wider ramifications of the Hechtian oscillator may implicate AGPs in osmosensing or gravisensing and other tropisms, leading us yet further towards the Holy Grail of plant growth.
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Affiliation(s)
- Derek T A Lamport
- School of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9QG, UK
| | - Li Tan
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA, 30602-4712, USA
| | - Michael A Held
- Department of Chemistry and Biochemistry, Ohio University, Athens, OH, 45701, USA
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13
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Suwińska A, Wasąg P, Zakrzewski P, Lenartowska M, Lenartowski R. Calreticulin is required for calcium homeostasis and proper pollen tube tip growth in Petunia. PLANTA 2017; 245:909-926. [PMID: 28078426 PMCID: PMC5391374 DOI: 10.1007/s00425-017-2649-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 01/05/2017] [Indexed: 05/19/2023]
Abstract
MAIN CONCLUSION Calreticulin is involved in stabilization of the tip-focused Ca 2+ gradient and the actin cytoskeleton arrangement and function that is required for several key processes driving Petunia pollen tube tip growth. Although the precise mechanism is unclear, stabilization of a tip-focused calcium (Ca2+) gradient seems to be critical for pollen germination and pollen tube growth. We hypothesize that calreticulin (CRT), a Ca2+-binding/buffering chaperone typically residing in the lumen of the endoplasmic reticulum (ER) of eukaryotic cells, is an excellent candidate to fulfill this role. We previously showed that in Petunia pollen tubes growing in vitro, CRT is translated on ER membrane-bound ribosomes that are abundant in the subapical zone of the tube, where CRT's Ca2+-buffering and chaperone activities might be particularly required. Here, we sought to determine the function of CRT using small interfering RNA (siRNA) to, for the first time in pollen tubes growing in vitro, knockdown expression of a gene. We demonstrate that siRNA-mediated post-transcriptional silencing of Petunia hybrida CRT gene (PhCRT) expression strongly impairs pollen tube growth, cytoplasmic zonation, actin cytoskeleton organization, and the tip-focused Ca2+ gradient. Moreover, reduction of CRT alters the localization and disturbs the structure of the ER in abnormally elongating pollen tubes. Finally, cytoplasmic streaming is inhibited, and most of the pollen tubes rupture. Our data clearly show an interplay between CRT, Ca2+ gradient, actin-dependent cytoplasmic streaming, organelle positioning, and vesicle trafficking during pollen tube elongation. Thus, we suggest that CRT functions in Petunia pollen tube growth by stabilizing Ca2+ homeostasis and acting as a chaperone to assure quality control of glycoproteins passing through the ER.
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Affiliation(s)
- Anna Suwińska
- Laboratory of Developmental Biology, Faculty of Biology and Environmental Protection, Nicolaus Copernicus University in Toruń, Toruń, Poland
| | - Piotr Wasąg
- Laboratory of Isotope and Instrumental Analysis, Faculty of Biology and Environmental Protection, Nicolaus Copernicus University in Toruń, Toruń, Poland
| | - Przemysław Zakrzewski
- Laboratory of Developmental Biology, Faculty of Biology and Environmental Protection, Nicolaus Copernicus University in Toruń, Toruń, Poland
| | - Marta Lenartowska
- Laboratory of Developmental Biology, Faculty of Biology and Environmental Protection, Nicolaus Copernicus University in Toruń, Toruń, Poland
| | - Robert Lenartowski
- Laboratory of Isotope and Instrumental Analysis, Faculty of Biology and Environmental Protection, Nicolaus Copernicus University in Toruń, Toruń, Poland.
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14
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The role of Ca 2+ and Ca 2+ channels in the gametophytic self-incompatibility of Pyrus pyrifolia. Cell Calcium 2016; 60:299-308. [DOI: 10.1016/j.ceca.2016.06.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Accepted: 06/23/2016] [Indexed: 11/15/2022]
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15
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Hafidh S, Fíla J, Honys D. Male gametophyte development and function in angiosperms: a general concept. PLANT REPRODUCTION 2016; 29:31-51. [PMID: 26728623 DOI: 10.1007/s00497-015-0272-4] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2015] [Accepted: 12/19/2015] [Indexed: 05/23/2023]
Abstract
Overview of pollen development. Male gametophyte development of angiosperms is a complex process that requires coordinated activity of different cell types and tissues of both gametophytic and sporophytic origin and the appropriate specific gene expression. Pollen ontogeny is also an excellent model for the dissection of cellular networks that control cell growth, polarity, cellular differentiation and cell signaling. This article describes two sequential phases of angiosperm pollen ontogenesis-developmental phase leading to the formation of mature pollen grains, and a functional or progamic phase, beginning with the impact of the grains on the stigma surface and ending at double fertilization. Here we present an overview of important cellular processes in pollen development and explosive pollen tube growth stressing the importance of reserves accumulation and mobilization and also the mutual activation of pollen tube and pistil tissues, pollen tube guidance and the communication between male and female gametophytes. We further describe the recent advances in regulatory mechanisms involved such as posttranscriptional regulation (including mass transcript storage) and posttranslational modifications to modulate protein function, intracellular metabolic signaling, ionic gradients such as Ca(2+) and H(+) ions, cell wall synthesis, protein secretion and intercellular signaling within the reproductive tissues.
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Affiliation(s)
- Said Hafidh
- Institute of Experimental Botany ASCR, v.v.i., Rozvojová 263, 165 00, Prague 6, Czech Republic
| | - Jan Fíla
- Institute of Experimental Botany ASCR, v.v.i., Rozvojová 263, 165 00, Prague 6, Czech Republic
| | - David Honys
- Institute of Experimental Botany ASCR, v.v.i., Rozvojová 263, 165 00, Prague 6, Czech Republic.
- Department of Experimental Plant Biology, Faculty of Science, Charles University in Prague, Viničná 5, 128 44, Prague 2, Czech Republic.
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16
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Luo N, Yan A, Yang Z. Measuring Exocytosis Rate Using Corrected Fluorescence Recovery After Photoconversion. Traffic 2016; 17:554-64. [PMID: 26822068 DOI: 10.1111/tra.12380] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 01/25/2016] [Accepted: 01/25/2016] [Indexed: 12/31/2022]
Abstract
Exocytosis plays crucial roles in regulating the distribution and function of plasma membrane (PM) and extracellular matrix proteins. However, measuring the exocytosis rate of a specific protein by conventional methods is very difficult because of exocytosis-independent trafficking such as endocytosis, which also affects membrane protein distribution. Here, we describe a novel method, corrected fluorescence recovery after photoconversion, in which exocytosis-dependent and -independent trafficking events are measured simultaneously to accurately determine exocytosis rate. In this method, the protein-of-interest is tagged with Dendra2, a green-to-red photoconvertible fluorescent protein. Following the photoconversion of PM-localized Dendra2, both the recovery of the green signal and the changes in the photoconverted red signal are measured, and the rate of exocytosis is calculated from the changing rates of these two signals.
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Affiliation(s)
- Nan Luo
- Center for Plant Cell Biology, Institute of Integrated Genome Biology, University of California, Riverside, CA, USA.,Department of Botany and Plant Sciences, University of California, Riverside, CA, 92521, USA
| | - An Yan
- Center for Plant Cell Biology, Institute of Integrated Genome Biology, University of California, Riverside, CA, USA.,Department of Botany and Plant Sciences, University of California, Riverside, CA, 92521, USA.,Current address: Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Zhenbiao Yang
- Center for Plant Cell Biology, Institute of Integrated Genome Biology, University of California, Riverside, CA, USA.,Department of Botany and Plant Sciences, University of California, Riverside, CA, 92521, USA
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17
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Wang H, Han S, Siao W, Song C, Xiang Y, Wu X, Cheng P, Li H, Jásik J, Mičieta K, Turňa J, Voigt B, Baluška F, Liu J, Wang Y, Zhao H. Arabidopsis Synaptotagmin 2 Participates in Pollen Germination and Tube Growth and Is Delivered to Plasma Membrane via Conventional Secretion. MOLECULAR PLANT 2015; 8:1737-50. [PMID: 26384245 DOI: 10.1016/j.molp.2015.09.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Revised: 08/18/2015] [Accepted: 09/05/2015] [Indexed: 05/15/2023]
Abstract
Arabidopsis synaptotagmin 2 (SYT2) has been reported to participate in an unconventional secretory pathway in somatic cells. Our results showed that SYT2 was expressed mainly in the pollen of Arabidopsis thaliana. The pollen of syt2 T-DNA and RNA interference mutant lines exhibited reduced total germination and impeded pollen tube growth. Analysis of the expression of SYT2-GFP fusion protein in the pollen tube indicates that SYT2 was localized to distinct, patchy compartments but could co-localize with the Golgi markers, BODIPY TR C5 ceramide and GmMan1-mCherry. However, SYT2-DsRed-E5 was localized to the plasma membrane in Arabidopsis suspension cells, in addition to the Golgi apparatus. The localization of SYT2 at the plasma membrane was further supported by immunofluorescence staining in pollen tubes. Moreover, brefeldin A treatment inhibited the transport of SYT2 to the plasma membrane and caused SYT2 to aggregate and form enlarged compartments. Truncation of the SYT2-C2AB domains also resulted in retention of SYT2 in the Golgi apparatus. An in vitro phospholipid-binding assay showed that SYT2-C2AB domains bind to the phospholipid membrane in a calcium-dependent manner. Take together, our results indicated that SYT2 was required for pollen germination and pollen tube growth, and was involved in conventional exocytosis.
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Affiliation(s)
- Hui Wang
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Science, Beijing Normal University, Beijing 100875, China
| | - Shengcheng Han
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Science, Beijing Normal University, Beijing 100875, China
| | - Wei Siao
- Department of Plant Cell Biology, IZMB, University of Bonn, Kirschallee 1, 53115 Bonn, Germany
| | - Chunqing Song
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Science, Beijing Normal University, Beijing 100875, China
| | - Yun Xiang
- School of Life Science, Lanzhou University, Lanzhou 730000, China
| | - Xiaorong Wu
- School of Life Science, Lanzhou University, Lanzhou 730000, China
| | - Pengyu Cheng
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Science, Beijing Normal University, Beijing 100875, China
| | - Hongjuan Li
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Science, Beijing Normal University, Beijing 100875, China
| | - Ján Jásik
- Comenius University Science Park, Comenius University, Bratislava, Mlynská dolina, 842 15 Bratislava 4, Slovakia
| | - Karol Mičieta
- Department of Botany, Faculty of Natural Sciences, Comenius University, Révová 39, 811 02 Bratislava 1, Slovakia
| | - Ján Turňa
- Department of Molecular Biology, Comenius University, Faculty of Natural Sciences, Mlynská dolina, pavilion B-2, 842 15 Bratislava 4, Slovakia
| | - Boris Voigt
- Department of Plant Cell Biology, IZMB, University of Bonn, Kirschallee 1, 53115 Bonn, Germany
| | - František Baluška
- Department of Plant Cell Biology, IZMB, University of Bonn, Kirschallee 1, 53115 Bonn, Germany; Institute of Botany, Slovak Academy of Sciences, Dubravska cesta 9, SK-84523 Bratislava, Slovak Republic.
| | - Jin Liu
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Science, Beijing Normal University, Beijing 100875, China
| | - Yingdian Wang
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Science, Beijing Normal University, Beijing 100875, China
| | - Heping Zhao
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Science, Beijing Normal University, Beijing 100875, China.
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18
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Burkart GM, Baskin TI, Bezanilla M. A family of ROP proteins that suppresses actin dynamics, and is essential for polarized growth and cell adhesion. J Cell Sci 2015; 128:2553-64. [PMID: 26045445 DOI: 10.1242/jcs.172445] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 05/31/2015] [Indexed: 01/22/2023] Open
Abstract
In plants, the ROP family of small GTPases has been implicated in the polarized growth of tip-growing cells, such as root hairs and pollen tubes; however, most of the data derive from overexpressing ROP genes or constitutively active and dominant-negative isoforms, whereas confirmation by using loss-of-function studies has generally been lacking. Here, in the model moss Physcomitrella patens, we study ROP signaling during tip growth by using a loss-of-function approach based on RNA interference (RNAi) to silence the entire moss ROP family. We find that plants with reduced expression of ROP genes, in addition to failing to initiate tip growth, have perturbed cell wall staining, reduced cell adhesion and have increased actin-filament dynamics. Although plants subjected to RNAi against the ROP family also have reduced microtubule dynamics, this reduction is not specific to loss of ROP genes, as it occurs when actin function is compromised chemically or genetically. Our data suggest that ROP proteins polarize the actin cytoskeleton by suppressing actin-filament dynamics, leading to an increase in actin filaments at the site of polarized secretion.
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Affiliation(s)
- Graham M Burkart
- Department of Biology, University of Massachusetts-Amherst, 611 N. Pleasant Street, Amherst, MA 01003, USA Plant Biology Graduate Program, University of Massachusetts-Amherst, 611 N. Pleasant Street, Amherst, MA 01003, USA
| | - Tobias I Baskin
- Department of Biology, University of Massachusetts-Amherst, 611 N. Pleasant Street, Amherst, MA 01003, USA
| | - Magdalena Bezanilla
- Department of Biology, University of Massachusetts-Amherst, 611 N. Pleasant Street, Amherst, MA 01003, USA
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19
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Williams JS, Wu L, Li S, Sun P, Kao TH. Insight into S-RNase-based self-incompatibility in Petunia: recent findings and future directions. FRONTIERS IN PLANT SCIENCE 2015; 6:41. [PMID: 25699069 PMCID: PMC4318427 DOI: 10.3389/fpls.2015.00041] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 01/15/2015] [Indexed: 05/29/2023]
Abstract
S-RNase-based self-incompatibility in Petunia is a self/non-self recognition system that allows the pistil to reject self-pollen to prevent inbreeding and to accept non-self pollen for outcrossing. Cloning of S-RNase in 1986 marked the beginning of nearly three decades of intensive research into the mechanism of this complex system. S-RNase was shown to be the sole female determinant in 1994, and the first male determinant, S-locus F-box protein1 (SLF1), was identified in 2004. It was discovered in 2010 that additional SLF proteins are involved in pollen specificity, and recently two S-haplotypes of Petunia inflata were found to possess 17 SLF genes based on pollen transcriptome analysis, further increasing the complexity of the system. Here, we first summarize the current understanding of how the interplay between SLF proteins and S-RNase in the pollen tube allows cross-compatible pollination, but results in self-incompatible pollination. We then discuss some of the aspects that are not yet elucidated, including uptake of S-RNase into the pollen tube, nature, and assembly of SLF-containing complexes, the biochemical basis for differential interactions between SLF proteins and S-RNase, and fate of non-self S-RNases in the pollen tube.
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Affiliation(s)
- Justin S. Williams
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, USA
| | - Lihua Wu
- Intercollege Graduate Degree Program in Plant Biology, Pennsylvania State University, University Park, PA, USA
| | - Shu Li
- Intercollege Graduate Degree Program in Plant Biology, Pennsylvania State University, University Park, PA, USA
| | - Penglin Sun
- Intercollege Graduate Degree Program in Plant Biology, Pennsylvania State University, University Park, PA, USA
| | - Teh-Hui Kao
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, USA
- Intercollege Graduate Degree Program in Plant Biology, Pennsylvania State University, University Park, PA, USA
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20
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Malhó R, Serrazina S, Saavedra L, Dias FV, Ul-Rehman R. Ion and lipid signaling in apical growth-a dynamic machinery responding to extracellular cues. FRONTIERS IN PLANT SCIENCE 2015; 6:816. [PMID: 26500662 PMCID: PMC4594336 DOI: 10.3389/fpls.2015.00816] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 09/18/2015] [Indexed: 05/07/2023]
Abstract
Apical cell growth seems to have independently evolved throughout the major lineages of life. To a certain extent, so does our body of knowledge on the mechanisms regulating this morphogenetic process. Studies on pollen tubes, root hairs, rhizoids, fungal hyphae, even nerve cells, have highlighted tissue and cell specificities but also common regulatory characteristics (e.g., ions, proteins, phospholipids) that our focused research sometimes failed to grasp. The working hypothesis to test how apical cell growth is established and maintained have thus been shaped by the model organism under study and the type of methods used to study them. The current picture is one of a dynamic and adaptative process, based on a spatial segregation of components that network to achieve growth and respond to environmental (extracellular) cues. Here, we explore some examples of our live imaging research, namely on cyclic nucleotide gated ion channels, lipid kinases and syntaxins involved in exocytosis. We discuss how their spatial distribution, activity and concentration suggest that the players regulating apical cell growth may display more mobility than previously thought. Furthermore, we speculate on the implications of such perspective in our understanding of the mechanisms regulating apical cell growth and their responses to extracellular cues.
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Affiliation(s)
- Rui Malhó
- *Correspondence: Rui Malhó and Reiaz Ul-Rehman, BioISI – Biosystems & Integrative Sciences Institute, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal, ,
| | | | - Laura Saavedra
- †Present address: Laura Saavedra, Cátedra de Fisiología Vegetal, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba, Córdoba, Argentina; Reiaz Ul-Rehman, Department of Bioresources, University of Kashmir, Hazratbal, Srinagar 190006, India
| | | | - Reiaz Ul-Rehman
- *Correspondence: Rui Malhó and Reiaz Ul-Rehman, BioISI – Biosystems & Integrative Sciences Institute, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal, ,
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21
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Pertl-Obermeyer H, Schulze WX, Obermeyer G. In vivo cross-linking combined with mass spectrometry analysis reveals receptor-like kinases and Ca2+ signalling proteins as putative interaction partners of pollen plasma membrane H+ ATPases. J Proteomics 2014; 108:17-29. [DOI: 10.1016/j.jprot.2014.05.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Revised: 04/23/2014] [Accepted: 05/01/2014] [Indexed: 10/25/2022]
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22
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Mizuta Y, Higashiyama T. Antisense gene inhibition by phosphorothioate antisense oligonucleotide in Arabidopsis pollen tubes. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2014; 78:516-26. [PMID: 24495108 DOI: 10.1111/tpj.12461] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Revised: 01/17/2014] [Accepted: 01/22/2014] [Indexed: 05/18/2023]
Abstract
Sexual reproduction is an essential biological event for proliferation of plants. The pollen tube (PT) that contained male gametes elongates and penetrates into the pistils for successful fertilization. However, the molecular mechanisms of plant fertilization remain largely unknown. Here, we report a transient inhibition of gene function using phosphorothioate antisense oligodeoxynucleotides (AS-ODNs) without cytofectin, which is a simple way to study gene function in Arabidopsis thaliana PTs. The PTs treated with AS-ODNs against both ANX1 and ANX2 showed short, knotted, and ruptured morphology in vitro/semi-in vitro, whereas normal PT growth was shown in its sense control in vitro/semi-in vitro. PT growth was impaired in a manner dependent on the dose of AS-ODNs against both ANX1 and ANX2 above 10 μm. The treatment with AS-ODNs against ROP1 and CalS5 resulted in waving PTs and in short PTs with a few callose plugs, respectively. The expression levels of the target genes in PTs treated with their AS-ODNs were lower than or similar to those in the sense control, indicating that the inhibition was directly or indirectly related to the expression of each mRNA. The AS-ODN against fluorescent protein (sGFP) led to reduced sGFP expression, suggesting that the AS-ODN suppressed protein expression. This method will enable the identification of reproductively important genes in Arabidopsis PTs.
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Affiliation(s)
- Yoko Mizuta
- Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8602, Japan; JST, ERATO, Higashiyama Live-Holonics Project, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8602, Japan
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23
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Bezvoda R, Pleskot R, Zárský V, Potocký M. Antisense oligodeoxynucleotide-mediated gene knockdown in pollen tubes. Methods Mol Biol 2014; 1080:231-6. [PMID: 24132433 DOI: 10.1007/978-1-62703-643-6_19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Specific gene knockdown mediated by the antisense oligodeoxynucleotides (AODNs) strategy recently emerged as a rapid and effective tool for probing gene role in plant cells, particularly tip-growing pollen tubes. Here, we describe the protocol for the successful employment of AODN technique in growing tobacco pollen tubes, covering AODN design, application, and analysis of the results. We also discuss the advantages and drawbacks of this method.
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Affiliation(s)
- Radek Bezvoda
- Department of Experimental Plant Biology, Faculty of Science, Charles University and Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Prague, Czech Republic
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24
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Wang H, Zhuang X, Cai Y, Cheung AY, Jiang L. Apical F-actin-regulated exocytic targeting of NtPPME1 is essential for construction and rigidity of the pollen tube cell wall. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 76:367-79. [PMID: 23906068 DOI: 10.1111/tpj.12300] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 07/15/2013] [Accepted: 07/18/2013] [Indexed: 05/03/2023]
Abstract
In tip-confined growing pollen tubes, delivery of newly synthesized cell wall materials to the rapidly expanding apical surface requires spatial organization and temporal regulation of the apical F-actin filament and exocytosis. In this study, we demonstrate that apical F-actin is essential for the rigidity and construction of the pollen tube cell wall by regulating exocytosis of Nicotiana tabacum pectin methylesterase (NtPPME1). Wortmannin disrupts the spatial organization of apical F-actin in the pollen tube tip and inhibits polar targeting of NtPPME1, which subsequently alters the rigidity and pectic composition of the pollen tube cell wall, finally causing growth arrest of the pollen tube. In addition to mechanistically linking cell wall construction and apical F-actin, wortmannin can be used as a useful tool for studying endomembrane trafficking and cytoskeletal organization in pollen tubes.
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Affiliation(s)
- Hao Wang
- School of Life Sciences, Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
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25
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Vanneste S, Friml J. Calcium: The Missing Link in Auxin Action. PLANTS (BASEL, SWITZERLAND) 2013; 2:650-75. [PMID: 27137397 PMCID: PMC4844386 DOI: 10.3390/plants2040650] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 10/07/2013] [Accepted: 10/10/2013] [Indexed: 01/18/2023]
Abstract
Due to their sessile lifestyles, plants need to deal with the limitations and stresses imposed by the changing environment. Plants cope with these by a remarkable developmental flexibility, which is embedded in their strategy to survive. Plants can adjust their size, shape and number of organs, bend according to gravity and light, and regenerate tissues that were damaged, utilizing a coordinating, intercellular signal, the plant hormone, auxin. Another versatile signal is the cation, Ca(2+), which is a crucial second messenger for many rapid cellular processes during responses to a wide range of endogenous and environmental signals, such as hormones, light, drought stress and others. Auxin is a good candidate for one of these Ca(2+)-activating signals. However, the role of auxin-induced Ca(2+) signaling is poorly understood. Here, we will provide an overview of possible developmental and physiological roles, as well as mechanisms underlying the interconnection of Ca(2+) and auxin signaling.
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Affiliation(s)
- Steffen Vanneste
- Plant Systems Biology, VIB, and Plant Biotechnology and Bio-informatics, Ghent University, Ghent 9052, Belgium.
| | - Jiří Friml
- Plant Systems Biology, VIB, and Plant Biotechnology and Bio-informatics, Ghent University, Ghent 9052, Belgium
- Institute of Science and Technology Austria (IST Austria), Klosterneuburg 3400, Austria
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26
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Hao H, Chen T, Fan L, Li R, Wang X. 2, 6-Dichlorobenzonitrile causes multiple effects on pollen tube growth beyond altering cellulose synthesis in Pinus bungeana Zucc. PLoS One 2013; 8:e76660. [PMID: 24146903 PMCID: PMC3795706 DOI: 10.1371/journal.pone.0076660] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Accepted: 08/26/2013] [Indexed: 01/14/2023] Open
Abstract
Cellulose is an important component of cell wall, yet its location and function in pollen tubes remain speculative. In this paper, we studied the role of cellulose synthesis in pollen tube elongation in Pinus bungeana Zucc. by using the specific inhibitor, 2, 6-dichlorobenzonitrile (DCB). In the presence of DCB, the growth rate and morphology of pollen tubes were distinctly changed. The organization of cytoskeleton and vesicle trafficking were also disturbed. Ultrastructure of pollen tubes treated with DCB was characterized by the loose tube wall and damaged organelles. DCB treatment induced distinct changes in tube wall components. Fluorescence labeling results showed that callose, and acidic pectin accumulated in the tip regions, whereas there was less cellulose when treated with DCB. These results were confirmed by FTIR microspectroscopic analysis. In summary, our findings showed that inhibition of cellulose synthesis by DCB affected the organization of cytoskeleton and vesicle trafficking in pollen tubes, and induced changes in the tube wall chemical composition in a dose-dependent manner. These results confirm that cellulose is involved in the establishment of growth direction of pollen tubes, and plays important role in the cell wall construction during pollen tube development despite its lower quantity.
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Affiliation(s)
- Huaiqing Hao
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Tong Chen
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Lusheng Fan
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Ruili Li
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Xiaohua Wang
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China
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27
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Abstract
Cellular organelles move within the cellular volume and the effect of the resulting drag forces on the liquid causes bulk movement in the cytosol. The movement of both organelles and cytosol leads to an overall motion pattern called cytoplasmic streaming or cyclosis. This streaming enables the active and passive transport of molecules and organelles between cellular compartments. Furthermore, the fusion and budding of vesicles with and from the plasma membrane (exo/endocytosis) allow for transport of material between the inside and the outside of the cell. In the pollen tube, cytoplasmic streaming and exo/endocytosis are very active and fulfill several different functions. In this review, we focus on the logistics of intracellular motion and transport processes as well as their biophysical underpinnings. We discuss various modeling attempts that have been performed to understand both long-distance shuttling and short-distance targeting of organelles. We show how the combination of mechanical and mathematical modeling with cell biological approaches has contributed to our understanding of intracellular transport logistics.
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Affiliation(s)
- Youssef Chebli
- Département de Sciences Biologiques, Institut de Recherche en Biologie Végétale, Université de Montréal, Montréal, Québec, Canada
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28
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Mähs A, Steinhorst L, Han JP, Shen LK, Wang Y, Kudla J. The calcineurin B-like Ca2+ sensors CBL1 and CBL9 function in pollen germination and pollen tube growth in Arabidopsis. MOLECULAR PLANT 2013; 6:1149-62. [PMID: 23741064 DOI: 10.1093/mp/sst095] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Ca(2+) has been established as an important second messenger regulating pollen germination and tube growth. However, to date, only a few signaling components have been identified to decode and relay Ca(2+) signals in growing pollen tubes. Here, we report a function for the calcineurin B-like (CBL) Ca(2+) sensor proteins CBL1 and CBL9 from Arabidopsis in pollen germination and tube growth. Both proteins are expressed in mature pollen and pollen tubes and impair pollen tube growth and morphology if transiently overexpressed in tobacco pollen. The induction of these phenotypes requires efficient plasma membrane targeting of CBL1 and is independent of Ca(2+) binding to the fourth EF-hand of CBL1. Overexpression of CBL1 or its closest homolog CBL9 in Arabidopsis renders pollen germination and tube growth hypersensitive towards high external K(+) concentrations while disruption of CBL1 and CBL9 reduces pollen tube growth under low K(+) conditions. Together, our data identify a crucial function for CBL1 and CBL9 in pollen germination and tube growth and suggest a model in which both proteins act at the plasma membrane through regulation of K(+) homeostasis.
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Affiliation(s)
- Anette Mähs
- Institut für Biologie und Biotechnologie der Pflanzen, Universität Münster, Schlossplatz 4, 48149 Münster, Germany
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29
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Vaškovičová K, Žárský V, Rösel D, Nikolič M, Buccione R, Cvrčková F, Brábek J. Invasive cells in animals and plants: searching for LECA machineries in later eukaryotic life. Biol Direct 2013; 8:8. [PMID: 23557484 PMCID: PMC3663805 DOI: 10.1186/1745-6150-8-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2012] [Accepted: 03/21/2013] [Indexed: 02/08/2023] Open
Abstract
Invasive cell growth and migration is usually considered a specifically metazoan phenomenon. However, common features and mechanisms of cytoskeletal rearrangements, membrane trafficking and signalling processes contribute to cellular invasiveness in organisms as diverse as metazoans and plants – two eukaryotic realms genealogically connected only through the last common eukaryotic ancestor (LECA). By comparing current understanding of cell invasiveness in model cell types of both metazoan and plant origin (invadopodia of transformed metazoan cells, neurites, pollen tubes and root hairs), we document that invasive cell behavior in both lineages depends on similar mechanisms. While some superficially analogous processes may have arisen independently by convergent evolution (e.g. secretion of substrate- or tissue-macerating enzymes by both animal and plant cells), at the heart of cell invasion is an evolutionarily conserved machinery of cellular polarization and oriented cell mobilization, involving the actin cytoskeleton and the secretory pathway. Its central components - small GTPases (in particular RHO, but also ARF and Rab), their specialized effectors, actin and associated proteins, the exocyst complex essential for polarized secretion, or components of the phospholipid- and redox- based signalling circuits (inositol-phospholipid kinases/PIP2, NADPH oxidases) are aparently homologous among plants and metazoans, indicating that they were present already in LECA. Reviewer: This article was reviewed by Arcady Mushegian, Valerian Dolja and Purificacion Lopez-Garcia.
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Affiliation(s)
- Katarína Vaškovičová
- Department of Cell Biology, Faculty of Science, Charles University in Prague, Vinicna 7, 128 43, Prague 2, Czech Republic
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30
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Zhu L, Zhang Y, Kang E, Xu Q, Wang M, Rui Y, Liu B, Yuan M, Fu Y. MAP18 regulates the direction of pollen tube growth in Arabidopsis by modulating F-actin organization. THE PLANT CELL 2013; 25:851-67. [PMID: 23463774 PMCID: PMC3634693 DOI: 10.1105/tpc.113.110528] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
For fertilization to occur in plants, the pollen tube must be guided to enter the ovule via the micropyle. Previous reports have implicated actin filaments, actin binding proteins, and the tip-focused calcium gradient as key contributors to polar growth of pollen tubes; however, the regulation of directional pollen tube growth is largely unknown. We reported previously that Arabidopsis thaliana MICROTUBULE-ASSOCIATED PROTEIN18 (MAP18) contributes to directional cell growth and cortical microtubule organization. The preferential expression of MAP18 in pollen and in pollen tubes suggests that MAP18 also may function in pollen tube growth. In this study, we demonstrate that MAP18 functions in pollen tubes by influencing actin organization, rather than microtubule assembly. In vitro biochemical results indicate that MAP18 exhibits Ca(2+)-dependent filamentous (F)-actin-severing activity. Abnormal expression of MAP18 in map18 and MAP18 OX plants was associated with disorganization of the actin cytoskeleton in the tube apex, resulting in aberrant pollen tube growth patterns and morphologies, inaccurate micropyle targeting, and fewer fertilization events. Experiments with MAP18 mutants created by site-directed mutagenesis suggest that F-actin-severing activity is essential to the effects of MAP18 on pollen tube growth direction. Our study demonstrates that in Arabidopsis, MAP18 guides the direction of pollen tube growth by modulating actin filaments.
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Kroeger J, Geitmann A. The pollen tube paradigm revisited. CURRENT OPINION IN PLANT BIOLOGY 2012; 15:618-24. [PMID: 23000432 DOI: 10.1016/j.pbi.2012.09.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 08/31/2012] [Accepted: 09/03/2012] [Indexed: 05/10/2023]
Abstract
The polar growth process characterizing pollen tube elongation has attracted numerous modeling attempts over the past years. While initial models focused on recreating the correct cellular geometry, recent models are increasingly based on experimentally assessed cellular parameters such as the dynamics of signaling processes and the mechanical properties of the cell wall. Recent modeling attempts have therefore substantially gained in biological relevance and predictive power. Different modeling methods are explained and the power and limitations of individual models are compared. Focus is on several recent models that use closed feedback loops in order to generate limit cycles representing the oscillatory behavior observed in growing tubes.
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Steinhorst L, Kudla J. Calcium - a central regulator of pollen germination and tube growth. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1833:1573-81. [PMID: 23072967 DOI: 10.1016/j.bbamcr.2012.10.009] [Citation(s) in RCA: 146] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Revised: 10/01/2012] [Accepted: 10/06/2012] [Indexed: 12/30/2022]
Abstract
Pollen tubes grow rapidly by very fast rates and reach extended lengths to bring about fertilization during plant reproduction. The pollen tube grows exclusively at its tip. Fundamental for such local, tip-focused growth are the presence of internal gradients and transmembrane fluxes of ions. Consequently, vegetative pollen tube cells are an excellent single cell model system to investigate cell biological processes of vesicle transport, cytoskeleton reorganization and regulation of ion transport. The second messenger Ca(2+) has emerged as a central and crucial modulator that not only regulates but also integrates the coordination each of these processes. In this review we reflect on recent advances in our understanding of the mechanisms of Ca(2+) function in pollen tube growth, focusing on its role in basic cellular processes such as control of cell growth, vesicular transport and intracellular signaling by localized gradients of second messengers. In particular we discuss new insights into the identity and role of Ca(2+) conductive ion channels and present experimental addressable hypotheses about their regulation. This article is part of a Special Issue entitled:12th European Symposium on Calcium.
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Affiliation(s)
- Leonie Steinhorst
- Institut für Biologie und Biotechnologie der Pflanzen, Universität Münster, Münster, Germany
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Guo F, McCubbin AG. The pollen-specific R-SNARE/longin PiVAMP726 mediates fusion of endo- and exocytic compartments in pollen tube tip growth. JOURNAL OF EXPERIMENTAL BOTANY 2012; 63:3083-95. [PMID: 22345643 PMCID: PMC3350921 DOI: 10.1093/jxb/ers023] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Revised: 01/13/2012] [Accepted: 01/17/2012] [Indexed: 05/06/2023]
Abstract
The growing pollen tube apex is dedicated to balancing exo- and endocytic processes to form a rapidly extending tube. As perturbation of either tends to cause a morphological phenotype, this system provides tractable model for studying these processes. Vesicle-associated membrane protein 7s (VAMP7s) are members of the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) family that mediate cognate membrane fusion but their role in pollen tube growth has not been investigated. This manuscript identifies PiVAMP726 of Petunia inflata as a pollen-specific VAMP7 that localizes to the inverted cone of transport vesicles at the pollen tube tip. The endocytic marker FM4-64 was found to colocalize with yellow fluorescent protein (YFP)-PiVAMP726, which is consistent with PiVAMP726 containing an amino-acid motif implicated in endosomal localization, At high overexpression levels, YFP- PiVAMP726 inhibited growth and caused the formation of novel membrane compartments within the pollen tube tip. Functional dissection of PiVAMP726 implicated the N-terminal longin domain in negative regulation of the SNARE activity, but not localization of PiVAMP726. Expression of the constitutively active C-terminal SNARE domain alone, in pollen tubes, generated similar phenotypes to the full-length protein, but the truncated domain was more potent than the wild-type protein at both inhibiting growth and forming the novel membrane compartments. Both endo- and exocytic markers localized to these compartments in addition to YFP-PiVAMP726, leading to the speculation that PiVAMP726 might be involved in the recycling of endocytic vesicles in tip growth.
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Affiliation(s)
| | - Andrew G. McCubbin
- School of Biological Sciences, Washington State University, Pullman, WA 99164-4236, USA
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Ul-Rehman R, Silva PA, Malhó R. Localization of Arabidopsis SYP125 syntaxin in the plasma membrane sub-apical and distal zones of growing pollen tubes. PLANT SIGNALING & BEHAVIOR 2011; 6:665-70. [PMID: 21499026 PMCID: PMC3172833 DOI: 10.4161/psb.6.5.14423] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2010] [Revised: 12/07/2010] [Accepted: 12/07/2010] [Indexed: 05/07/2023]
Abstract
Tip growth in pollen tubes occurs by continuous vesicle secretion and delivery of new wall material, but the exact sub-cellular location of endocytic and exocytic domains remains unclear. Here we studied the localization of the Arabidopsis thaliana pollen specific syntaxin SYP125 using GFP-fusion constructs expressed in Nicotiana tobaccum pollen tubes. In agreement with the predicted role for syntaxins, SYP125 was found to be associated with the plasma membrane and apical vesicles in growing cells. At the plasma membrane, SYP125 was asymmetrically localized with a higher labeling 20-35 μm behind the apex, a distribution which is distinct from SYP124, another pollen-specific syntaxin. Competition with a related dominant negative mutant affected the specific distribution of SYP125 but not tip growth. Co-expression of the phosphatidylinositol-4-monophosphate-5-kinase 4 (PIP5K4) or of the small GTPase Rab11 perturbed polarity and the normal distribution of GFP-SYP but did not inhibit the accumulation in vesicles or at the plasma membrane. Taken together, our results corroborates previous observations that in normal growing pollen tubes, the asymmetric distribution of syntaxins helps to define exocytic sub-domains but requires the involvement of additional signaling and functional mechanisms, namely phosphoinositides and small GTPases. The localization of syntaxins at different membrane domains likely depends on the interaction with specific partners not yet identified.
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Affiliation(s)
- Reiaz Ul-Rehman
- Universidade de Lisboa, Faculdade de Ciências de Lisboa, BioFIG, Lisbon, Portugal
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Silva PÂ, Ul-Rehman R, Rato C, Di Sansebastiano GP, Malhó R. Asymmetric localization of Arabidopsis SYP124 syntaxin at the pollen tube apical and sub-apical zones is involved in tip growth. BMC PLANT BIOLOGY 2010; 10:179. [PMID: 20718953 PMCID: PMC3095309 DOI: 10.1186/1471-2229-10-179] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2010] [Accepted: 08/18/2010] [Indexed: 05/02/2023]
Abstract
BACKGROUND The continuous polarized vesicle secretion in pollen tubes is essential for tip growth but the location of endo- and exocytic sub-domains remains however controversial. In this report we aimed to show that Arabidopsis thaliana syntaxins are involved in this process and contribute to spatially define exocytosis and membrane recycling. RESULTS Using GFP-fusion constructs, we imaged the distribution of pollen-specific (AtSYP124) and non-pollen syntaxins (AtSYP121 and AtSYP122) in transiently transformed Nicotiana tabacum pollen tubes. All three proteins associate with the plasma membrane and with apical vesicles indicating a conserved action mechanism for all SYPs. However, the GFP tagged SYP124 showed a specific distribution with a higher labelling at the plasma membrane flanks, 10-25 mum behind the apex. This distribution is affected by Ca2+ fluxes as revealed by treatment with Gd3+ (an inhibitor of extracellular Ca2+ influx) and TMB-8 (an inhibitor of intracellular Ca2+ release). Both inhibitors decreased growth rate but the distribution of SYP124 at the plasma membrane was more strongly affected by Gd3+. Competition with a related dominant negative mutant affected the specific distribution of SYP124 but not tip growth. In contrast, co-expression of the phosphatidylinositol-4-monophosphate 5-kinase 4 (PIP5K4) or of the small GTPase Rab11 perturbed polarity and the normal distribution of GFP-SYP but did not inhibit the accumulation in vesicles or at the plasma membrane. CONCLUSIONS The results presented suggest that in normal growing pollen tubes, a net exocytic flow occurs in the flanks of the tube apex mediated by SYP124. The specific distribution of SYP124 at the plasma membrane is affected by changes in Ca2+ levels in agreement with the importance of this ion for exocytosis. Apical growth and the specific localization of SYP124 were affected by regulators of membrane secretion (Ca2+, PIP5K4 and Rab11) but competition with a dominant negative mutant affected only SYP distribution. These data thus suggest that syntaxins alone do not provide the level of specificity that is required for apical growth and that additional signalling and functional mechanisms are required.
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Affiliation(s)
- Pedro Ângelo Silva
- Universidade de Lisboa, Faculdade de Ciências de Lisboa, BioFIG, 1749-016 Lisboa, Portugal
| | - Reiaz Ul-Rehman
- Universidade de Lisboa, Faculdade de Ciências de Lisboa, BioFIG, 1749-016 Lisboa, Portugal
| | - Cláudia Rato
- Universidade de Lisboa, Faculdade de Ciências de Lisboa, BioFIG, 1749-016 Lisboa, Portugal
- Institute of Medical Sciences, School of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD, UK
| | | | - Rui Malhó
- Universidade de Lisboa, Faculdade de Ciências de Lisboa, BioFIG, 1749-016 Lisboa, Portugal
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36
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Zhang Y, He J, Lee D, McCormick S. Interdependence of endomembrane trafficking and actin dynamics during polarized growth of Arabidopsis pollen tubes. PLANT PHYSIOLOGY 2010; 152:2200-10. [PMID: 20181757 PMCID: PMC2850033 DOI: 10.1104/pp.109.142349] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
During polarized growth of pollen tubes, endomembrane trafficking and actin polymerization are two critical processes that establish membrane/wall homeostasis and maintain growth polarity. Fine-tuned interactions between these two processes are therefore necessary but poorly understood. To better understand such cross talk in the model plant Arabidopsis (Arabidopsis thaliana), we first established optimized concentrations of drugs that interfere with either endomembrane trafficking or the actin cytoskeleton, then examined pollen tube growth using fluorescent protein markers that label transport vesicles, endosomes, or the actin cytoskeleton. Both brefeldin A (BFA) and wortmannin disturbed the motility and structural integrity of ARA7- but not ARA6-labeled endosomes, suggesting heterogeneity of the endosomal populations. Disrupting endomembrane trafficking by BFA or wortmannin perturbed actin polymerization at the apical region but not in the longitudinal actin cables in the shank. The interference of BFA/wortmannin with actin polymerization was progressive rather than rapid, suggesting an indirect effect, possibly due to perturbed endomembrane trafficking of certain membrane-localized signaling proteins. Both the actin depolymerization drug latrunculin B and the actin stabilization drug jasplakinolide rapidly disrupted transport of secretory vesicles, but each drug caused distinct responses on different endosomal populations labeled by ARA6 or ARA7, indicating that a dynamic actin cytoskeleton was critical for some steps in endomembrane trafficking. Our results provide evidence of cross talk between endomembrane trafficking and the actin cytoskeleton in pollen tubes.
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37
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Hepler PK, Winship LJ. Calcium at the cell wall-cytoplast interface. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2010; 52:147-60. [PMID: 20377677 DOI: 10.1111/j.1744-7909.2010.00923.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Attention is given to the role of Ca(2+) at the interface between the cell wall and the cytoplast, especially as seen in pollen tubes. While the cytoplasm directs the synthesis and deposition of the wall, it is less well appreciated that the wall exerts considerable self control and influences activities of the cytoplasm. Ca(2+) participates as a crucial factor in this two way communication. In the cytoplasm, a [Ca(2+)] above 0.1 microM, regulates myriad processes, including secretion of cell wall components. In the cell wall Ca(2+), at 10 microM to 10 mM, binds negative charges on pectins and imparts structural rigidity to the wall. The plasma membrane occupies a pivotal position between these two compartments, where selective channels regulate influx of Ca(2+), and specific carriers pump the ion back into the wall. In addition we draw attention to different factors, which either respond to the wall or are present in the wall, and usually generate elevated [Ca(2+)] in the cytoplasm. These factors include: (i) stretch activated channels; (ii) calmodulin; (iii) annexins; (iv) wall associated kinases; (v) oligogalacturonides; and (vi) extracellular adenosine 5'-triphosphate. Together they provide evidence for a rich and multifaceted system of communication between the cytoplast and cell wall, with Ca(2+) as a carrier of information.
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Affiliation(s)
- Peter K Hepler
- Department of Biology, University of Massachusetts, Amherst, MA 01003, USA.
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38
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Deng F, Zhu S, Wu L, Cheng B. Effects of low-energy argon ion implantation on the dynamic organization of the actin cytoskeleton during maize pollen germination. GENETICS AND MOLECULAR RESEARCH 2010; 9:785-96. [DOI: 10.4238/vol9-2gmr768] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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39
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The regulation of vesicle trafficking by small GTPases and phospholipids during pollen tube growth. ACTA ACUST UNITED AC 2009; 23:87-93. [DOI: 10.1007/s00497-009-0118-z] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2009] [Accepted: 10/22/2009] [Indexed: 01/01/2023]
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40
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Pertl H, Schulze WX, Obermeyer G. The Pollen Organelle Membrane Proteome Reveals Highly Spatial−Temporal Dynamics during Germination and Tube Growth of Lily Pollen. J Proteome Res 2009; 8:5142-52. [DOI: 10.1021/pr900503f] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Heidi Pertl
- Molecular Plant Biophysics and Biochemistry, Deptartment of Molecular Biology, University of Salzburg, Billrothstrasse 11, 5020 Salzburg, Austria, and Max-Planck-Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Golm, Germany
| | - Waltraud X. Schulze
- Molecular Plant Biophysics and Biochemistry, Deptartment of Molecular Biology, University of Salzburg, Billrothstrasse 11, 5020 Salzburg, Austria, and Max-Planck-Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Golm, Germany
| | - Gerhard Obermeyer
- Molecular Plant Biophysics and Biochemistry, Deptartment of Molecular Biology, University of Salzburg, Billrothstrasse 11, 5020 Salzburg, Austria, and Max-Planck-Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Golm, Germany
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41
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McKenna ST, Kunkel JG, Bosch M, Rounds CM, Vidali L, Winship LJ, Hepler PK. Exocytosis precedes and predicts the increase in growth in oscillating pollen tubes. THE PLANT CELL 2009; 21:3026-40. [PMID: 19861555 PMCID: PMC2782290 DOI: 10.1105/tpc.109.069260] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2009] [Revised: 09/28/2009] [Accepted: 10/14/2009] [Indexed: 05/18/2023]
Abstract
We examined exocytosis during oscillatory growth in lily (Lilium formosanum and Lilium longiflorum) and tobacco (Nicotiana tabacum) pollen tubes using three markers: (1) changes in cell wall thickness by Nomarski differential interference contrast (DIC), (2) changes in apical cell wall fluorescence in cells stained with propidium iodide (PI), and (3) changes in apical wall fluorescence in cells expressing tobacco pectin methyl esterase fused to green fluorescent protein (PME-GFP). Using PI fluorescence, we quantified oscillatory changes in the amount of wall material from both lily and tobacco pollen tubes. Measurement of wall thickness by DIC was only possible with lily due to limitations of microscope resolution. PME-GFP, a direct marker for exocytosis, only provides information in tobacco because its expression in lily causes growth inhibition and cell death. We show that exocytosis in pollen tubes oscillates and leads the increase in growth rate; the mean phase difference between exocytosis and growth is -98 degrees +/- 3 degrees in lily and -124 degrees +/- 4 degrees in tobacco. Statistical analyses reveal that the anticipatory increase in wall material predicts, to a high degree, the rate and extent of the subsequent growth surge. Exocytosis emerges as a prime candidate for the initiation and regulation of oscillatory pollen tube growth.
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Affiliation(s)
| | - Joseph G. Kunkel
- Department of Biology, University of Massachusetts, Amherst, Massachusetts 01003
| | - Maurice Bosch
- Institute of Biological, Environmental, and Rural Sciences, Aberystwyth University Plas Gogerddan, Aberystwyth, SY23 3EB, United Kingdom
| | - Caleb M. Rounds
- Department of Biology, University of Massachusetts, Amherst, Massachusetts 01003
| | - Luis Vidali
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, Massachusetts 01609
| | | | - Peter K. Hepler
- Department of Biology, University of Massachusetts, Amherst, Massachusetts 01003
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Moscatelli A, Idilli AI. Pollen tube growth: a delicate equilibrium between secretory and endocytic pathways. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2009; 51:727-39. [PMID: 19686370 DOI: 10.1111/j.1744-7909.2009.00842.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Although pollen tube growth is a prerequisite for higher plant fertilization and seed production, the processes leading to pollen tube emission and elongation are crucial for understanding the basic mechanisms of tip growth. It was generally accepted that pollen tube elongation occurs by accumulation and fusion of Golgi-derived secretory vesicles (SVs) in the apical region, or clear zone, where they were thought to fuse with a restricted area of the apical plasma membrane (PM), defining the apical growth domain. Fusion of SVs at the tip reverses outside cell wall material and provides new segments of PM. However, electron microscopy studies have clearly shown that the PM incorporated at the tip greatly exceeds elongation and a mechanism of PM retrieval was already postulated in the mid-nineteenth century. Recent studies on endocytosis during pollen tube growth showed that different endocytic pathways occurred in distinct zones of the tube, including the apex, and led to a new hypothesis to explain vesicle accumulation at the tip; namely, that endocytic vesicles contribute substantially to V-shaped vesicle accumulation in addition to SVs and that exocytosis does not involve the entire apical domain. New insights suggested the intriguing hypothesis that modulation between exo- and endocytosis in the apex contributes to maintain PM polarity in terms of lipid/protein composition and showed distinct degradation pathways that could have different functions in the physiology of the cell. Pollen tube growth in vivo is closely regulated by interaction with style molecules. The study of endocytosis and membrane recycling in pollen tubes opens new perspectives to studying pollen tube-style interactions in vivo.
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Affiliation(s)
- Alessandra Moscatelli
- Dipartimento di Biologia L. Gorini, Università degli Studi di Milano, Milano, Italy.
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43
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Myers C, Romanowsky SM, Barron YD, Garg S, Azuse CL, Curran A, Davis RM, Hatton J, Harmon AC, Harper JF. Calcium-dependent protein kinases regulate polarized tip growth in pollen tubes. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2009; 59:528-39. [PMID: 19392698 DOI: 10.1111/j.1365-313x.2009.03894.x] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Calcium signals are critical for the regulation of polarized growth in many eukaryotic cells, including pollen tubes and neurons. In plants, the regulatory pathways that code and decode Ca(2+) signals are poorly understood. In Arabidopsis thaliana, genetic evidence presented here indicates that pollen tube tip growth involves the redundant activity of two Ca(2+)-dependent protein kinases (CPKs), isoforms CPK17 and -34. Both isoforms appear to target to the plasma membrane, as shown by imaging of CPK17-yellow fluorescent protein (YFP) and CPK34-YFP in growing pollen tubes. Segregation analyses from two independent sets of T-DNA insertion mutants indicate that a double disruption of CPK17 and -34 results in an approximately 350-fold reduction in pollen transmission efficiency. The near sterile phenotype of homozygous double mutants could be rescued through pollen expression of a CPK34-YFP fusion. In contrast, a transgene rescue was blocked by mutations engineered to disrupt the Ca(2+)-activation mechanism of CPK34 (CPK34-YFP-E465A,E500A), providing in vivo evidence linking Ca(2+) activation to a biological function of a CPK. While double mutant pollen tubes displayed normal morphology, relative growth rates for the most rapidly growing tubes were reduced by more than three-fold compared with wild type. In addition, while most mutant tubes appeared to grow far enough to reach ovules, the vast majority (>90%) still failed to locate and fertilize ovules. Together, these results provide genetic evidence that CPKs are essential to pollen fitness, and support a mechanistic model in which CPK17 and -34 transduce Ca(2+) signals to increase the rate of pollen tube tip growth and facilitate a response to tropism cues.
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Affiliation(s)
- Candace Myers
- Biochemistry Department MS200, University of Nevada, Reno, NV 89557, USA
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44
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Wang Y, Chen T, Zhang C, Hao H, Liu P, Zheng M, Baluška F, Šamaj J, Lin J. Nitric oxide modulates the influx of extracellular Ca2+ and actin filament organization during cell wall construction in Pinus bungeana pollen tubes. THE NEW PHYTOLOGIST 2009; 182:851-862. [PMID: 19646068 DOI: 10.1111/j.1469-8137.2009.02820.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Nitric oxide (NO) plays a key role in many physiological processes in plants, including pollen tube growth. Here, effects of NO on extracellular Ca(2+) flux and microfilaments during cell wall construction in Pinus bungeana pollen tubes were investigated. Extracellular Ca(2+) influx, the intracellular Ca(2+) gradient, patterns of actin organization, vesicle trafficking and cell wall deposition upon treatment with the NO donor S-nitroso-N-acetylpenicillamine (SNAP), the NO synthase (NOS) inhibitor N(omega)-nitro-L-arginine (L-NNA) or the NO scavenger 2-(4-carboxyphenyl)-4, 4, 5, 5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO) were analyzed. SNAP enhanced pollen tube growth in a dose-dependent manner, while L-NNA and cPTIO inhibited NO production and arrested pollen tube growth. Noninvasive detection and microinjection of a Ca(2+) indicator revealed that SNAP promoted extracellular Ca(2+) influx and increased the steepness of the tip-focused Ca(2+) gradient, while cPTIO and L-NNA had the opposite effect. Fluorescence labeling indicated that SNAP, cPTIO and L-NNA altered actin organization, which subsequently affected vesicle trafficking. Finally, the configuration and/or distribution of cell wall components such as pectins and callose were significantly altered in response to L-NNA. Fourier transform infrared (FTIR) microspectroscopy confirmed the changes in the chemical composition of walls. Our results indicate that NO affects the configuration and distribution of cell wall components in pollen tubes by altering extracellular Ca(2+) influx and F-actin organization.
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Affiliation(s)
- Yuhua Wang
- Key Laboratory of Photosynthesis and Molecular Environmental Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- Graduate School of Chinese Academy of Sciences, Beijing 100049, China
- The College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | - Tong Chen
- Key Laboratory of Photosynthesis and Molecular Environmental Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Chunyang Zhang
- Key Laboratory of Photosynthesis and Molecular Environmental Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- Graduate School of Chinese Academy of Sciences, Beijing 100049, China
| | - Huaiqing Hao
- Key Laboratory of Photosynthesis and Molecular Environmental Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Peng Liu
- Key Laboratory of Photosynthesis and Molecular Environmental Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- Graduate School of Chinese Academy of Sciences, Beijing 100049, China
| | - Maozhong Zheng
- Key Laboratory of Photosynthesis and Molecular Environmental Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- Graduate School of Chinese Academy of Sciences, Beijing 100049, China
| | - František Baluška
- Institute of Cellular and Molecular Botany, Rheinische Friedrich-Wilhelms-University Bonn, Department of Plant Cell Biology, Kirschallee 1, D-53115 Bonn, Germany
| | - Jozef Šamaj
- Institute of Cellular and Molecular Botany, Rheinische Friedrich-Wilhelms-University Bonn, Department of Plant Cell Biology, Kirschallee 1, D-53115 Bonn, Germany
- Institute of Plant Genetics and Biotechnology, Slovak Academy of Sciences, Akademicka 2, SK-95007, Nitra, Slovak Republic
- Palacky University Olomouc, Faculty of Natural Science, Olomouc 771 46, Czech Republic
| | - Jinxing Lin
- Key Laboratory of Photosynthesis and Molecular Environmental Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
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45
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Lee CB, Kim S, McClure B. A pollen protein, NaPCCP, that binds pistil arabinogalactan proteins also binds phosphatidylinositol 3-phosphate and associates with the pollen tube endomembrane system. PLANT PHYSIOLOGY 2009; 149:791-802. [PMID: 19098095 PMCID: PMC2633847 DOI: 10.1104/pp.108.127936] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2008] [Accepted: 12/18/2008] [Indexed: 05/21/2023]
Abstract
As pollen tubes grow toward the ovary, they are in constant contact with the pistil extracellular matrix (ECM). ECM components are taken up during growth, and some pistil molecules exert their effect inside the pollen tube. For instance, the Nicotiana alata 120-kD glycoprotein (120K) is an abundant arabinogalactan protein that is taken up from the ECM; it has been detected in association with pollen tube vacuoles, but the transport pathway between these compartments is unknown. We recently identified a pollen C2 domain-containing protein (NaPCCP) that binds to the carboxyl-terminal domain of 120K. As C2 domain proteins mediate protein-lipid interactions, NaPCCP could function in intracellular transport of 120K in pollen tubes. Here, we describe binding studies showing that the NaPCCP C2 domain is functional and that binding is specific for phosphatidylinositol 3-phosphate. Subcellular fractionation, immunolocalization, and live imaging results show that NaPCCP is associated with the plasma membrane and internal pollen tube vesicles. Colocalization between an NaPCCPgreen fluorescent protein fusion and internalized FM4-64 suggest an association with the endosomal system. NaPCCP localization is altered in pollen tubes rejected by the self-incompatibility mechanism, but our hypothesis is that it has a general function in the transport of endocytic cargo rather than a specific function in self-incompatibility. NaPCCP represents a bifunctional protein with both phosphatidylinositol 3-phosphate- and arabinogalactan protein-binding domains. Therefore, it could function in the transport of pistil ECM proteins in the pollen tube endomembrane system.
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Affiliation(s)
- Christopher B Lee
- Division of Biological Sciences, Interdisciplinary Plant Group, University of Missouri, Columbia, Missouri 65211, USA
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46
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Geitmann A, Dumais J. Not-so-tip-growth. PLANT SIGNALING & BEHAVIOR 2009; 4:136-8. [PMID: 19649191 PMCID: PMC2637501 DOI: 10.4161/psb.4.2.7633] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2008] [Accepted: 12/16/2008] [Indexed: 05/19/2023]
Abstract
In tip-growing plant cells such as pollen tubes and root hairs, surface expansion is confined to the cell apex. Vesicles containing pectic cell wall material are delivered to this apical region to provide the material necessarily to build the expanding cell wall. Quantification of wall expansion reveals that the surface expansion rates are not highest at the pole but instead in an annular region around the pole. These findings raise the question of the precise localization of exocytosis events in these cells. Recently, we used spatio-temporal image correlation spectroscopy (STICS) in combination with high temporal resolution confocal imaging to characterize the intracellular movement of vesicles in growing pollen tubes. These observations, together with the analysis of FRAP (fluorescence recovery after photobleaching) experiments, indicate that exocytosis is likely to occur predominantly in the same annular region where wall expansion rates are greatest. Therefore, tip growth in plant cells does not seem to happen exactly at the tip.
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Affiliation(s)
- Anja Geitmann
- Institut de Recherche en Biologie Végétale, Département de Sciences Biologiques, Université de Montréal, Montréal, Québec, Canada.
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Cai G, Cresti M. Organelle motility in the pollen tube: a tale of 20 years. JOURNAL OF EXPERIMENTAL BOTANY 2009; 60:495-508. [PMID: 19112169 DOI: 10.1093/jxb/ern321] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Organelle movement is an evident feature of pollen tubes and is essential for the process of tube growth because it enables the proper distribution of organelles and the accumulation of secretory vesicles in the tube apex. Organelles move along the actin filaments through dynamic interactions with myosin but other proteins are probably responsible for control of this activity. The role of microtubules and microtubule-based motors is less clear and somewhat enigmatic. Nevertheless, the pollen tube is an excellent cell model in which to study and analyse the molecular mechanisms that drive and control organelle motility in relation to plant cell expansion. Current knowledge and the main scientific discoveries in this field of research over the last 20 years are summarized here. Future prospects in the study of the molecular mechanisms that mediate organelle transport and vesicle accumulation during pollen tube elongation are also discussed.
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Affiliation(s)
- Giampiero Cai
- Dipartimento Scienze Ambientali, Università di Siena, via Mattioli 4, I-53100 Siena, Italy.
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Sousa E, Kost B, Malhó R. Arabidopsis phosphatidylinositol-4-monophosphate 5-kinase 4 regulates pollen tube growth and polarity by modulating membrane recycling. THE PLANT CELL 2008; 20:3050-64. [PMID: 19033528 PMCID: PMC2613665 DOI: 10.1105/tpc.108.058826] [Citation(s) in RCA: 120] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2008] [Revised: 10/19/2008] [Accepted: 11/09/2008] [Indexed: 05/18/2023]
Abstract
Phosphatidylinositol-4-monophosphate 5-kinases produce phosphatidylinositol (4,5)-bisphosphate [PtdIns(4,5)P(2)] and have been implicated in vesicle trafficking and cytoskeletal rearrangements. Here, we adopted a reverse genetics approach to investigate the function of the Arabidopsis thaliana pollen-expressed gene encoding phosphatidylinositol-4-monophosphate 5-kinase 4 (PIP5K4). Pollen germination, tube growth, and polarity were significantly impaired in homozygous mutant plants lacking PIP5K4 transcript. In vitro, supplementation with PtdIns(4,5)P(2) rescued these phenotypes. In vivo, mutant pollen fertilized ovules, leading to normal seed set and silique length. However, fertilization took longer than in wild-type plants, and the pip5k4 null mutant allele was transmitted through the pollen at a reduced frequency. Analysis of endocytic events using FM1-43 (or FM4-64) suggested a reduction in endocytosis and membrane recycling in pip5k4 null mutant pollen tubes. Imaging of elongating tobacco (Nicotiana tabacum) pollen tubes transiently transformed with a PIP5K4-green fluorescent protein fusion construct revealed that the protein localized to the plasma membrane, particularly in the subapical region. Overexpression of PIP5K4-GFP delocalized the protein to the apical region of the plasma membrane, perturbed pollen tube growth, and caused apical cell wall thickening. Thus, PIP5K4 plays a crucial role in regulating the polarity of pollen tubes. This study supports a model for membrane secretion and recycling where the apical and subapical regions appear to contain the components required to promote and sustain growth.
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Affiliation(s)
- Eva Sousa
- Universidade de Lisboa, Faculdade de Ciências de Lisboa, Instituto Ciéncia Aplicada e Tecnologia, 1749-016 Lisboa, Portugal
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Lee CB, Swatek KN, McClure B. Pollen proteins bind to the C-terminal domain of Nicotiana alata pistil arabinogalactan proteins. J Biol Chem 2008; 283:26965-73. [PMID: 18678868 DOI: 10.1074/jbc.m804410200] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pollen tube growth is influenced by interaction between pollen proteins and the pistil extracellular matrix. The transmitting tract-specific glycoprotein (NaTTS) and 120-kDa glycoprotein (120K) are two pistil arabinogalactan proteins (AGPs) that share a conserved C-terminal domain (CTD) and directly influence pollen tubes in Nicotiana alata. 120K and other extracellular matrix proteins are taken up and transported to vacuoles of growing pollen tubes. We hypothesize that signaling and trafficking processes inside pollen tubes are important for controlling pollen tube growth. We performed a yeast two-hybrid screen of pollen cDNAs using sequences from 120K and NaTTS as baits. We found that an S-RNase-binding protein (SBP1), a C2 domain-containing protein (NaPCCP), and a putative cysteine protease bound to the AGP baits. SBP1 from Petunia hybrida and Solanum chacoense is a putative E3 ubiquitin ligase that binds to S-RNase and other proteins. C2 domain-containing proteins bind lipids and can regulate myriad cellular processes. Cysteine proteases are often associated with the degradation of vacuolar proteins. Expression analysis revealed that transcripts for these proteins are expressed in mature pollen. NaPCCP and NaSBP1 were characterized further because of their potential roles in signaling and trafficking. In vitro pull-down assays verified binding between maltose-binding protein (MBP) fusions, MBP::NaPCCP or MBP::NaSBP1 and glutathione S-transferase (GST), GST::AGP CTD fusions. NaSBP1 binds to the AGP CTDs through its helical and RING domains. NaPCCP binds through its C-terminal region. Binding between NaPCCP and NaSBP1 and the pistil AGPs may contribute to signaling and trafficking inside pollen tubes growing in planta.
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Affiliation(s)
- Christopher B Lee
- Divisions of Biological Sciences, Interdisciplinary Plant Group, Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211, USA
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Wu X, Chen T, Zheng M, Chen Y, Teng N, Samaj J, Baluska F, Lin J. Integrative proteomic and cytological analysis of the effects of extracellular Ca(2+) influx on Pinus bungeana pollen tube development. J Proteome Res 2008; 7:4299-312. [PMID: 18715029 DOI: 10.1021/pr800241u] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Ca (2+) is an essential ion in the control of pollen germination and tube growth. However, the control of pollen tube development by Ca (2+) signaling and its interactions with cytoskeletal components, energy-providing pathways, and cell-expansion machinery remain elusive. Here, we used nifedipine (Nif) to study Ca (2+) functions in differential protein expression and other cellular processes in Pinus bungeana pollen tube growth. Proteomics analysis indicated that 50 proteins showed differential expression with varying doses of Nif. Thirty-four of these were homologous to previously reported proteins and were classified into different functional categories closely related to tip-growth machinery. Blocking the L-type Ca (2+) channel with Nif in the pollen tube membrane induced several early alterations within a short time, including a reduction of extracellular Ca (2+) influx and a subsequently dramatic decrease in cytosolic free Ca (2+) concentration ([Ca (2+)] c), concomitant with ultrastructural abnormalities and changes in the abundance of proteins involved in energy production and signaling. Secondary alterations included actin filament depolymerization, disrupted patterns of endocytosis/exocytosis, and cell wall remodeling, along with changes in the proteins involved in these processes. These results suggested that extracellular Ca (2+) influx was necessary for the maintenance of the typical tip-focused [Ca (2+)] c gradient in the P. bungeana pollen tube, and that reduced adenosine triphosphate production (ATP), depolymerization of the cytoskeleton, and abnormal endocytosis/exocytosis, together with enhanced rigidity of cell walls, were responsible for the growth arrest observed in pollen tubes treated with Nif.
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Affiliation(s)
- Xiaoqin Wu
- Key Laboratory of Photosynthesis and Molecular Environment Physiology, Institute of Botany, Chinese Academy of Sciences, 100093 Beijing, China
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