1
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Zhuang Y, Wang Y, Jiao C, Shang Z, Huang S. Arabidopsis VILLIN5 bundles actin filaments using a novel mechanism. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024. [PMID: 39093617 DOI: 10.1111/tpj.16956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Revised: 07/10/2024] [Accepted: 07/19/2024] [Indexed: 08/04/2024]
Abstract
Being a bona fide actin bundler, Arabidopsis villin5 (VLN5) plays a crucial role in regulating actin stability and organization within pollen tubes. Despite its significance, the precise mechanism through which VLN5 bundles actin filaments has remained elusive. Through meticulous deletion analysis, we have unveiled that the link between gelsolin repeat 6 (G6) and the headpiece domain (VHP), rather than VHP itself, is indispensable for VLN5-mediated actin bundling. Further refinement of this region has pinpointed a critical sequence spanning from Val763 to Ser823, essential for VLN5's actin-bundling activity. Notably, the absence of Val763-Ser823 in VLN5 results in decreased filamentous decoration within pollen tubes and a diminished ability to rescue actin bundling defects in vln2vln5 mutant pollen tubes compared to intact VLN5. Moreover, our findings highlight that the Val763-Ser823 sequence harbors a binding site for F-actin, suggesting that this linker-based F-actin binding site, in conjunction with the F-actin binding site localized in G1-G6, enables a single VLN5 to concurrently bind to two adjacent actin filaments. Therefore, our study unveils a novel mechanism by which VLN5 bundles actin filaments.
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Affiliation(s)
- Yuhui Zhuang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
- College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Yingjie Wang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Cuixia Jiao
- College of Life Sciences, Hebei Normal University, Shijiazhuang, 050016, China
| | - Zhonglin Shang
- College of Life Sciences, Hebei Normal University, Shijiazhuang, 050016, China
| | - Shanjin Huang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
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2
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Han J, Yang X, Cai Y, Qiao F, Tao J, Zhu X, Mou Q, An J, Hu J, Li Z, Guan Y. MORN motif-containing protein OsMORN1 and OsMORN2 are crucial for rice pollen viability and cold tolerance. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024; 119:998-1013. [PMID: 38761113 DOI: 10.1111/tpj.16812] [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: 07/24/2023] [Revised: 04/23/2024] [Accepted: 05/03/2024] [Indexed: 05/20/2024]
Abstract
The pollen viability directly affects the pollination process and the ultimate grain yield of rice. Here, we identified that the MORN motif-containing proteins, OsMORN1 and OsMORN2, had a crucial role in maintaining pollen fertility. Compared with the wild type (WT), the pollen viability of the osmorn1 and osmorn2 mutants was reduced, and pollen germination was abnormal, resulting in significantly lower spikelet fertility, seed-setting rate, and grain yield per plant. Further investigation revealed that OsMORN1 was localized to the Golgi apparatus and lipid droplets. Lipids associated with pollen viability underwent alterations in osmorn mutants, such as the diacylglyceride (18:3_18:3) was 5.1-fold higher and digalactosyldiacylglycerol (18:2_18:2) was 5.2-fold lower in osmorn1, while the triacylglycerol (TG) (16:0_18:2_18:3) was 8.3-fold higher and TG (16:0_18:1_18:3) was 8.5-fold lower in osmorn2 than those in WT. Furthermore, the OsMORN1/2 was found to be associated with rice cold tolerance, as osmorn1 and osmorn2 mutants were more sensitive to chilling stress than WT. The mutants displayed increased hydrogen peroxide accumulation, reduced antioxidant enzyme activities, elevated malondialdehyde content, and a significantly decreased seedling survival rate. Lipidomics analysis revealed distinct alterations in lipids under low temperature, highlighting significant changes in TG (18:2_18:3_18:3) and TG (18:4_18:2_18:2) in osmorn1, TG (16:0_18:2_18:2) and PI (17:2_18:3) in osmorn2 compared to the WT. Therefore, it suggested that OsMORN1 and OsMORN2 regulate both pollen viability and cold tolerance through maintaining lipid homeostasis.
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Affiliation(s)
- Jiajun Han
- Seed Science Center, The Advanced Seed Institute, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Xiaoying Yang
- Guangdong Provincial Key Laboratory of Plant Molecular Breeding, State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou, 510640, China
| | - Yibei Cai
- Seed Science Center, The Advanced Seed Institute, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Fengpei Qiao
- Seed Science Center, The Advanced Seed Institute, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Ji Tao
- Seed Science Center, The Advanced Seed Institute, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Xiaobo Zhu
- Hainan Research Institute, Zhejiang University, Sanya, 572025, China
| | - Qingshan Mou
- Hainan Research Institute, Zhejiang University, Sanya, 572025, China
| | - Jianyu An
- Seed Science Center, The Advanced Seed Institute, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Jin Hu
- Seed Science Center, The Advanced Seed Institute, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, 310058, China
- Hainan Research Institute, Zhejiang University, Sanya, 572025, China
| | - Zhan Li
- Guangdong Provincial Key Laboratory of Plant Molecular Breeding, State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou, 510640, China
| | - Yajing Guan
- Seed Science Center, The Advanced Seed Institute, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, 310058, China
- Hainan Research Institute, Zhejiang University, Sanya, 572025, China
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3
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Lu Y, Cheng K, Tang H, Li J, Zhang C, Zhu H. The role of Rab GTPase in Plant development and stress. JOURNAL OF PLANT PHYSIOLOGY 2024; 296:154239. [PMID: 38574493 DOI: 10.1016/j.jplph.2024.154239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Revised: 03/26/2024] [Accepted: 03/26/2024] [Indexed: 04/06/2024]
Abstract
Small GTPase is a type of crucial regulator in eukaryotes. It acts as a molecular switch by binding with GTP and GDP in cytoplasm, affecting various cellular processes. Small GTPase were divided into five subfamilies based on sequence, structure and function: Ras, Rho, Rab, Arf/Sar and Ran, with Rab being the largest subfamily. Members of the Rab subfamily play an important role in regulating complex vesicle transport and microtubule system activity. Plant cells are composed of various membrane-bound organelles, and vesicle trafficking is fundamental to the existence of plants. At present, the function of some Rab members, such as RabA1a, RabD2b/c and RabF2, has been well characterized in plants. This review summarizes the role of Rab GTPase in regulating plant tip growth, morphogenesis, fruit ripening and stress response, and briefly describes the regulatory mechanisms involved. It provides a reference for further alleviating environmental stress, improving plant resistance and even improving fruit quality.
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Affiliation(s)
- Yao Lu
- The College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, 100083, China.
| | - Ke Cheng
- The College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, 100083, China.
| | - Hui Tang
- The College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, 100083, China.
| | - Jinyan Li
- The College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, 100083, China.
| | - Chunjiao Zhang
- Supervision, Inspection & Testing Center of Agricultural Products Quality, Ministry of Agriculture and Rural Affairs, Beijing, 100083, China.
| | - Hongliang Zhu
- The College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, 100083, China.
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4
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Koenig AM, Liu B, Hu J. Visualizing the dynamics of plant energy organelles. Biochem Soc Trans 2023; 51:2029-2040. [PMID: 37975429 PMCID: PMC10754284 DOI: 10.1042/bst20221093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 11/06/2023] [Accepted: 11/08/2023] [Indexed: 11/19/2023]
Abstract
Plant organelles predominantly rely on the actin cytoskeleton and the myosin motors for long-distance trafficking, while using microtubules and the kinesin motors mostly for short-range movement. The distribution and motility of organelles in the plant cell are fundamentally important to robust plant growth and defense. Chloroplasts, mitochondria, and peroxisomes are essential organelles in plants that function independently and coordinately during energy metabolism and other key metabolic processes. In response to developmental and environmental stimuli, these energy organelles modulate their metabolism, morphology, abundance, distribution and motility in the cell to meet the need of the plant. Consistent with their metabolic links in processes like photorespiration and fatty acid mobilization is the frequently observed inter-organellar physical interaction, sometimes through organelle membranous protrusions. The development of various organelle-specific fluorescent protein tags has allowed the simultaneous visualization of organelle movement in living plant cells by confocal microscopy. These energy organelles display an array of morphology and movement patterns and redistribute within the cell in response to changes such as varying light conditions, temperature fluctuations, ROS-inducible treatments, and during pollen tube development and immune response, independently or in association with one another. Although there are more reports on the mechanism of chloroplast movement than that of peroxisomes and mitochondria, our knowledge of how and why these three energy organelles move and distribute in the plant cell is still scarce at the functional and mechanistic level. It is critical to identify factors that control organelle motility coupled with plant growth, development, and stress response.
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Affiliation(s)
- Amanda M. Koenig
- Michigan State University-Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, U.S.A
| | - Bo Liu
- Department of Plant Biology, University of California, Davis, CA, U.S.A
| | - Jianping Hu
- Michigan State University-Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, U.S.A
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5
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Khoso MA, Zhang H, Khoso MH, Poudel TR, Wagan S, Papiashvili T, Saha S, Ali A, Murtaza G, Manghwar H, Liu F. Synergism of vesicle trafficking and cytoskeleton during regulation of plant growth and development: A mechanistic outlook. Heliyon 2023; 9:e21976. [PMID: 38034654 PMCID: PMC10682163 DOI: 10.1016/j.heliyon.2023.e21976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 11/01/2023] [Accepted: 11/01/2023] [Indexed: 12/02/2023] Open
Abstract
The cytoskeleton is a fundamental component found in all eukaryotic organisms, serving as a critical factor in various essential cyto-biological mechanisms, particularly in the locomotion and morphological transformations of plant cells. The cytoskeleton is comprised of three main components: microtubules (MT), microfilaments (MF), and intermediate filaments (IF). The cytoskeleton plays a crucial role in the process of cell wall formation and remodeling throughout the growth and development of cells. It is a highly organized and regulated network composed of filamentous components. In the basic processes of intracellular transport, such as mitosis, cytokinesis, and cell polarity, the plant cytoskeleton plays a crucial role according to recent studies. The major flaws in the organization of the cytoskeletal framework are at the root of the aberrant organogenesis currently observed in plant mutants. The regulation of protein compartmentalization and abundance within cells is predominantly governed by the process of vesicle/membrane transport, which plays a crucial role in several signaling cascades.The regulation of membrane transport in eukaryotic cells is governed by a diverse array of proteins. Recent developments in genomics have provided new tools to study the evolutionary relationships between membrane proteins in different plant species. It is known that members of the GTPases, COP, SNAREs, Rabs, tethering factors, and PIN families play essential roles in vesicle transport between plant, animal, and microbial species. This Review presents the latest research on the plant cytoskeleton, focusing on recent developments related to the cytoskeleton and summarizing the role of various proteins in vesicle transport. In addition, the report predicts future research direction of plant cytoskeleton and vesicle trafficking, potential research priorities, and provides researchers with specific pointers to further investigate the significant link between cytoskeleton and vesicle trafficking.
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Affiliation(s)
- Muneer Ahmed Khoso
- Lushan Botanical Garden, Chinese Academy of Sciences, Jiujiang 332000, China
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, Department of Life Science, Northeast Forestry University, Harbin 150040, China
| | - Hailong Zhang
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, Department of Life Science, Northeast Forestry University, Harbin 150040, China
| | - Mir Hassan Khoso
- Department of Biochemistry, Shaheed Mohtarma Benazir Bhutto Medical University Larkana, Pakistan
| | - Tika Ram Poudel
- Feline Research Center of National Forestry and Grassland Administration, College of Wildlife and Protected Area, Northeast Forestry University, Harbin 150040, China
| | - Sindho Wagan
- Laboratory of Pest Physiology Biochemistry and Molecular Toxicology Department of Forest Protection Northeast Forestry University Harbin 150040, China
| | - Tamar Papiashvili
- School of Economics and Management Ministry of Education, Northeast Forestry University, Harbin 150040, China
| | - Sudipta Saha
- School of Forestry, Department of Silviculture, Northeast Forestry University, Harbin 150040, China
| | - Abid Ali
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, Department of Life Science, Northeast Forestry University, Harbin 150040, China
| | - Ghulam Murtaza
- Department of Biochemistry and Molecular Biology Harbin Medical University China, China
| | - Hakim Manghwar
- Lushan Botanical Garden, Chinese Academy of Sciences, Jiujiang 332000, China
| | - Fen Liu
- Lushan Botanical Garden, Chinese Academy of Sciences, Jiujiang 332000, China
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6
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Zhang R, Xu Y, Yi R, Shen J, Huang S. Actin cytoskeleton in the control of vesicle transport, cytoplasmic organization, and pollen tube tip growth. PLANT PHYSIOLOGY 2023; 193:9-25. [PMID: 37002825 DOI: 10.1093/plphys/kiad203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 03/08/2023] [Accepted: 03/17/2023] [Indexed: 06/19/2023]
Abstract
Pollen tubes extend rapidly via tip growth. This process depends on a dynamic actin cytoskeleton, which has been implicated in controlling organelle movements, cytoplasmic streaming, vesicle trafficking, and cytoplasm organization in pollen tubes. In this update review, we describe the progress in understanding the organization and regulation of the actin cytoskeleton and the function of the actin cytoskeleton in controlling vesicle traffic and cytoplasmic organization in pollen tubes. We also discuss the interplay between ion gradients and the actin cytoskeleton that regulates the spatial arrangement and dynamics of actin filaments and the organization of the cytoplasm in pollen tubes. Finally, we describe several signaling components that regulate actin dynamics in pollen tubes.
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Affiliation(s)
- Ruihui Zhang
- National Key Laboratory of Crop Genetic Improvement, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Yanan Xu
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Ran Yi
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Jiangfeng Shen
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Shanjin Huang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
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7
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Mansoor S, Ali A, Kour N, Bornhorst J, AlHarbi K, Rinklebe J, Abd El Moneim D, Ahmad P, Chung YS. Heavy Metal Induced Oxidative Stress Mitigation and ROS Scavenging in Plants. PLANTS (BASEL, SWITZERLAND) 2023; 12:3003. [PMID: 37631213 PMCID: PMC10459657 DOI: 10.3390/plants12163003] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 08/16/2023] [Accepted: 08/18/2023] [Indexed: 08/27/2023]
Abstract
Although trace elements are essential for life, environmental contamination due to metal accumulation and overuse in various sectors, such as healthcare, agriculture, industry, and cosmetics, poses significant health concerns. Exposure of plants to heavy metals leads to the overproduction of reactive oxygen species (ROS) due to their ability to change mitochondrial membrane permeability and restrict the action of ROS clearance enzymes in the cellular antioxidant system. The interaction of ROS with cellular membranes, heavy-metal-induced interactions directly or indirectly with different macromolecules, and signaling pathways leads to the accumulation of environmental pollutants and oxidative stress in exposed organisms. The heavy metal-ROS-cell signaling axis affects various pathological processes such as ATP depletion, excess ROS production, mitochondrial respiratory chain damage, decoupling of oxidative phosphorylation, and mitochondrial death. This review focuses on discussing the toxic effects of different heavy metals on plants, with particular emphasis on oxidative stress, its consequences, and mitigation strategies.
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Affiliation(s)
- Sheikh Mansoor
- Department of Plant Resources and Environment, Jeju National University, Jeju 63243, Republic of Korea;
| | - Asif Ali
- Biomedical Sciences Research Institute, School of Biomedical Sciences, Ulster University, Coleraine BT52 1SA, Northern Ireland, UK;
| | - Navneet Kour
- Division of Biochemistry, Sher-e-Kashmir University of Agricultural Sciences and Technology of Jammu, Jammu 180009, India
| | - Julia Bornhorst
- Food Chemistry, Faculty of Mathematics and Natural Sciences, University of Wuppertal, 20, 42119 Wuppertal, Germany;
- Trace Age-DFG Research Unit on Interactions of Essential Trace Elements in Healthy and Diseased Elderly (FOR 2558), Berlin-Potsdam-Jena-Wuppertal, 14558 Nuthetal, Germany
| | - Khadiga AlHarbi
- Department of Biology, College of Science, Princess Nourah bint Abdulrahman University, P.O. Box 84428, Riyadh 11671, Saudi Arabia;
| | - Jörg Rinklebe
- Laboratory of Soil and Groundwater Management, Institute of Foundation Engineering, Water and Waste Management, School of Architecture and Civil Engineering, University of Wuppertal, Pauluskirchstraße 7, 42285 Wuppertal, Germany;
| | - Diaa Abd El Moneim
- Department of Plant Production (Genetic Branch), Faculty of Environmental Agricultural Sciences, Arish University, El-Arish 45511, Egypt;
| | - Parvaiz Ahmad
- Department of Botany, Government Degree College, Pulwama 192301, Jammu and Kashmir, India
| | - Yong Suk Chung
- Department of Plant Resources and Environment, Jeju National University, Jeju 63243, Republic of Korea;
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8
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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: 1.0] [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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9
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Yan H, Zhuang M, Xu X, Li S, Yang M, Li N, Du X, Hu K, Peng X, Huang W, Wu H, Tse YC, Zhao L, Wang H. Autophagy and its mediated mitochondrial quality control maintain pollen tube growth and male fertility in Arabidopsis. Autophagy 2023; 19:768-783. [PMID: 35786359 PMCID: PMC9980518 DOI: 10.1080/15548627.2022.2095838] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Macroautophagy/autophagy, a major catabolic pathway in eukaryotes, participates in plant sexual reproduction including the processes of male gametogenesis and the self-incompatibility response. Rapid pollen tube growth is another essential reproductive process that is metabolically highly demanding to drive the vigorous cell growth for delivery of male gametes for fertilization in angiosperms. Whether and how autophagy operates to maintain the homeostasis of pollen tubes remains unknown. Here, we provide evidence that autophagy is elevated in growing pollen tubes and critically required during pollen tube growth and male fertility in Arabidopsis. We demonstrate that SH3P2, a critical non-ATG regulator of plant autophagy, colocalizes with representative ATG proteins during autophagosome biogenesis in growing pollen tubes. Downregulation of SH3P2 expression significantly disrupts Arabidopsis pollen germination and pollen tube growth. Further analysis of organelle dynamics reveals crosstalk between autophagosomes and prevacuolar compartments following the inhibition of phosphatidylinositol 3-kinase. In addition, time-lapse imaging and tracking of ATG8e-labeled autophagosomes and depolarized mitochondria demonstrate that they interact specifically via the ATG8-family interacting motif (AIM)-docking site to mediate mitophagy. Ultrastructural identification of mitophagosomes and two additional forms of autophagosomes imply that multiple types of autophagy are likely to function simultaneously within pollen tubes. Altogether, our results suggest that autophagy is functionally crucial for mediating mitochondrial quality control and canonical cytoplasm recycling during pollen tube growth.Abbreviations: AIM: ATG8-family interacting motif; ATG8: autophagy related 8; ATG5: autophagy related 5; ATG7: autophagy related 7; BTH: acibenzolar-S-methyl; DEX: dexamethasone; DNP: 2,4-dinitrophenol; GFP: green fluorescent protein; YFP: yellow fluorescent protein; PtdIns3K: phosphatidylinositol 3-kinase; PtdIns3P: phosphatidylinositol-3-phosphate; PVC: prevacuolar compartment; SH3P2: SH3 domain-containing protein 2.
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Affiliation(s)
- He Yan
- Department of Cell and Developmental Biology, College of Life Sciences, South China Agricultural University, Guangzhou, Hong Kong, China
| | - Menglong Zhuang
- Department of Cell and Developmental Biology, College of Life Sciences, South China Agricultural University, Guangzhou, Hong Kong, China
| | - Xiaoyu Xu
- Department of Cell and Developmental Biology, College of Life Sciences, South China Agricultural University, Guangzhou, Hong Kong, China
| | - Shanshan Li
- Department of Cell and Developmental Biology, College of Life Sciences, South China Agricultural University, Guangzhou, Hong Kong, China
| | - Mingkang Yang
- Department of Cell and Developmental Biology, College of Life Sciences, South China Agricultural University, Guangzhou, Hong Kong, China.,State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou null China
| | - Nianle Li
- Department of Cell and Developmental Biology, College of Life Sciences, South China Agricultural University, Guangzhou, Hong Kong, China
| | - Xiaojuan Du
- Department of Cell and Developmental Biology, College of Life Sciences, South China Agricultural University, Guangzhou, Hong Kong, China
| | - Kangwei Hu
- Department of Cell and Developmental Biology, College of Life Sciences, South China Agricultural University, Guangzhou, Hong Kong, China
| | - Xiaomin Peng
- Department of Cell and Developmental Biology, College of Life Sciences, South China Agricultural University, Guangzhou, Hong Kong, China
| | - Wei Huang
- Department of Cell and Developmental Biology, College of Life Sciences, South China Agricultural University, Guangzhou, Hong Kong, China.,State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou null China
| | - Hong Wu
- Department of Cell and Developmental Biology, College of Life Sciences, South China Agricultural University, Guangzhou, Hong Kong, China.,State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou null China
| | - Yu Chung Tse
- Core Research Facilities, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Lifeng Zhao
- Department of Cell and Developmental Biology, College of Life Sciences, South China Agricultural University, Guangzhou, Hong Kong, China
| | - Hao Wang
- Department of Cell and Developmental Biology, College of Life Sciences, South China Agricultural University, Guangzhou, Hong Kong, China
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10
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Lu Q, Liu X, Qu X, Huang S. Visualization and Quantification of the Dynamics of Actin Filaments in Arabidopsis Pollen Tubes. Methods Mol Biol 2023; 2604:285-295. [PMID: 36773243 DOI: 10.1007/978-1-0716-2867-6_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
The actin cytoskeleton plays an essential role in the regulation of polarized pollen tube growth, and its functions are dictated by its spatial organization and dynamics. Here we describe an assay to monitor the dynamics of actin filaments decorated with Lifeact-mEGFP in Arabidopsis pollen tubes using spinning disk confocal microscopy and measuring the parameters associated with their dynamics. The method allows us to assess the dynamics of actin filaments in growing Arabidopsis pollen tubes.
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Affiliation(s)
- Qiaonan Lu
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Xiaonan Liu
- School of Life Sciences, Qilu Normal University, Jinan, China
| | - Xiaolu Qu
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, China.
| | - Shanjin Huang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China.
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11
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Zhou Z, Zheng S, Haq SIU, Zheng D, Qiu QS. Regulation of pollen tube growth by cellular pH and ions. JOURNAL OF PLANT PHYSIOLOGY 2022; 277:153792. [PMID: 35973258 DOI: 10.1016/j.jplph.2022.153792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Revised: 07/29/2022] [Accepted: 08/06/2022] [Indexed: 06/15/2023]
Abstract
Tip growth of the pollen tube is a model system for the study of cell polarity establishment in flowering plants. The tip growth of the pollen tube displays an oscillating pattern corresponding to cellular ion and pH dynamics. Therefore, cellular pH and ions play an important role in pollen growth and development. In this review, we summarized the current advances in understanding the function of cellular pH and ions in regulating pollen tube growth. We analyzed the physiological roles and underlying mechanisms of cellular pH and ions, including Ca2+, K+, and Cl-, in regulating pollen tube growth. We further examined the function of Ca2+ in regulating cytoskeletons, small G proteins, and cell wall development in relation to pollen tube growth. We also examined the regulatory roles of cellular pH in pollen tube growth as well as pH regulation of ion flow, cell wall development, auxin signaling, and cytoskeleton function in pollen. In addition, we assessed the regulation of pollen tube growth by proton pumps and the maintenance of pH homeostasis in the trans-Golgi network by ion transporters. The interplay of ion homeostasis and pH dynamics was also assessed. We discussed the unanswered questions regarding pollen tube growth that need to be addressed in the future.
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Affiliation(s)
- Zhenguo Zhou
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, 73000, China.
| | - Sheng Zheng
- College of Life Sciences, Northwest Normal University, Lanzhou, Gansu, 730070, China; Academy of Plateau Science and Sustainability, Qinghai Normal University, Xining, Qinghai, 810016, China
| | - Syed Inzimam Ul Haq
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, 73000, China
| | - Dianfeng Zheng
- College of Coastal Agricultural Sciences, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China
| | - Quan-Sheng Qiu
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, 73000, China; Academy of Plateau Science and Sustainability, Qinghai Normal University, Xining, Qinghai, 810016, China; College of Coastal Agricultural Sciences, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China.
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12
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Yu SX, Jiang YT, Lin WH. Ovule initiation: the essential step controlling offspring number in Arabidopsis. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2022; 64:1469-1486. [PMID: 35713236 DOI: 10.1111/jipb.13314] [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: 05/09/2022] [Accepted: 06/14/2022] [Indexed: 06/15/2023]
Abstract
Seed is the offspring of angiosperms. Plants produce large numbers of seeds to ensure effective reproduction and survival in varying environments. Ovule is a fundamentally important organ and is the precursor of the seed. In Arabidopsis and other plants characterized by multi-ovulate ovaries, ovule initiation determines the maximal ovule number, thus greatly affecting seed number per fruit and seed yield. Investigating the regulatory mechanism of ovule initiation has both scientific and economic significance. However, the genetic and molecular basis underlying ovule initiation remains unclear due to technological limitations. Very recently, rules governing the multiple ovules initiation from one placenta have been identified, the individual functions and crosstalk of phytohormones in regulating ovule initiation have been further characterized, and new regulators of ovule boundary are reported, therefore expanding the understanding of this field. In this review, we present an overview of current knowledge in ovule initiation and summarize the significance of ovule initiation in regulating the number of plant offspring, as well as raise insights for the future study in this field that provide potential routes for the improvement of crop yield.
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Affiliation(s)
- Shi-Xia Yu
- The Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
- Shanghai Collaborative Innovation Center of Agri-Seeds/Joint Center for Single Cell Biology, Shanghai Jiao Tong University, Shanghai, 200240, China
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Yu-Tong Jiang
- The Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Wen-Hui Lin
- The Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
- Shanghai Collaborative Innovation Center of Agri-Seeds/Joint Center for Single Cell Biology, Shanghai Jiao Tong University, Shanghai, 200240, China
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13
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Cai G. The legacy of kinesins in the pollen tube thirty years later. Cytoskeleton (Hoboken) 2022; 79:8-19. [PMID: 35766009 PMCID: PMC9542081 DOI: 10.1002/cm.21713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2022] [Revised: 06/06/2022] [Accepted: 06/27/2022] [Indexed: 11/10/2022]
Abstract
The pollen tube is fundamental in the reproduction of seed plants. Particularly in angiosperms, we now have much information about how it grows, how it senses extracellular signals, and how it converts them into a directional growth mechanism. The expansion of the pollen tube is also related to dynamic cytoplasmic processes based on the cytoskeleton (such as polymerization/depolymerization of microtubules and actin filaments) or motor activity along with the two cytoskeletal systems and is dependent on motor proteins. While a considerable amount of information is available for the actomyosin system in the pollen tube, the role of microtubules in the transport of organelles or macromolecular structures is still quite uncertain despite that 30 years ago the first work on the presence of kinesins in the pollen tube was published. Since then, progress has been made in elucidating the role of kinesins in plant cells. However, their role within the pollen tube is still enigmatic. In this review, I will postulate some roles of kinesins in the pollen tube 30 years after their initial discovery based on information obtained in other plant cells in the meantime. The most concrete hypotheses predict that kinesins in the pollen tube enable the short movement of specific organelles or contribute to generative cell or sperm cell transport, as well as mediate specific steps in the process of endocytosis.
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Affiliation(s)
- Giampiero Cai
- Dipartimento Scienze della Vita, Università di Siena, via Mattioli 4, Siena, Italy
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14
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Çetinbaş-Genç A, Conti V, Cai G. Let's shape again: the concerted molecular action that builds the pollen tube. PLANT REPRODUCTION 2022; 35:77-103. [PMID: 35041045 DOI: 10.1007/s00497-022-00437-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 01/06/2022] [Indexed: 06/14/2023]
Abstract
The pollen tube is being subjected to control by a complex network of communication that regulates its shape and the misfunction of a single component causes specific deformations. In flowering plants, the pollen tube is a tubular extension of the pollen grain required for successful sexual reproduction. Indeed, maintaining the unique shape of the pollen tube is essential for the pollen tube to approach the embryo sac. Many processes and molecules (such as GTPase activity, phosphoinositides, Ca2+ gradient, distribution of reactive oxygen species and nitric oxide, nonuniform pH values, organization of the cytoskeleton, balance between exocytosis and endocytosis, and cell wall structure) play key and coordinated roles in maintaining the cylindrical shape of pollen tubes. In addition, the above factors must also interact with each other so that the cell shape is maintained while the pollen tube follows chemical signals in the pistil that guide it to the embryo sac. Any intrinsic changes (such as erroneous signals) or extrinsic changes (such as environmental stresses) can affect the above factors and thus fertilization by altering the tube morphology. In this review, the processes and molecules that enable the development and maintenance of the unique shape of pollen tubes in angiosperms are presented emphasizing their interaction with specific tube shape. Thus, the purpose of the review is to investigate whether specific deformations in pollen tubes can help us to better understand the mechanism underlying pollen tube shape.
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Affiliation(s)
- Aslıhan Çetinbaş-Genç
- Department of Biology, Marmara University, Göztepe Campus, 34722, Kadıköy, Istanbul, Turkey.
| | - Veronica Conti
- Department of Life Sciences, University of Siena, via Mattioli 4, 53100, Siena, Italy
| | - Giampiero Cai
- Department of Life Sciences, University of Siena, via Mattioli 4, 53100, Siena, Italy
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15
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Parrotta L, Faleri C, Del Casino C, Mareri L, Aloisi I, Guerriero G, Hausman JF, Del Duca S, Cai G. Biochemical and cytological interactions between callose synthase and microtubules in the tobacco pollen tube. PLANT CELL REPORTS 2022; 41:1301-1318. [PMID: 35303156 PMCID: PMC9110548 DOI: 10.1007/s00299-022-02860-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 03/02/2022] [Indexed: 06/09/2023]
Abstract
KEY MESSAGE The article concerns the association between callose synthase and cytoskeleton by biochemical and ultrastructural analyses in the pollen tube. Results confirmed this association and immunogold labeling showed a colocalization. Callose is a cell wall polysaccharide involved in fundamental biological processes, from plant development to the response to abiotic and biotic stress. To gain insight into the deposition pattern of callose, it is important to know how the enzyme callose synthase is regulated through the interaction with the vesicle-cytoskeletal system. Actin filaments likely determine the long-range distribution of callose synthase through transport vesicles but the spatial/biochemical relationships between callose synthase and microtubules are poorly understood, although experimental evidence supports the association between callose synthase and tubulin. In this manuscript, we further investigated the association between callose synthase and microtubules through biochemical and ultrastructural analyses in the pollen tube model system, where callose is an essential component of the cell wall. Results by native 2-D electrophoresis, isolation of callose synthase complex and far-western blot confirmed that callose synthase is associated with tubulin and can therefore interface with cortical microtubules. In contrast, actin and sucrose synthase were not permanently associated with callose synthase. Immunogold labeling showed colocalization between the enzyme and microtubules, occasionally mediated by vesicles. Overall, the data indicate that pollen tube callose synthase exerts its activity in cooperation with the microtubular cytoskeleton.
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Affiliation(s)
- Luigi Parrotta
- Department of Biological, Geological and Environmental Sciences, University of Bologna, Via Irnerio 42, 40126, Bologna, Italy.
- Interdepartmental Centre for Agri-Food Industrial Research, University of Bologna, Via Quinto Bucci 336, 47521, Cesena, Italy.
| | - Claudia Faleri
- Department of Life Sciences, University of Siena, Via P.A. Mattioli 4, 53100, Siena, Italy
| | - Cecilia Del Casino
- Department of Life Sciences, University of Siena, Via P.A. Mattioli 4, 53100, Siena, Italy
| | - Lavinia Mareri
- Department of Life Sciences, University of Siena, Via P.A. Mattioli 4, 53100, Siena, Italy
| | - Iris Aloisi
- Department of Biological, Geological and Environmental Sciences, University of Bologna, Via Irnerio 42, 40126, Bologna, Italy
| | - Gea Guerriero
- Research and Innovation Department, Luxembourg Institute of Science and Technology, 5 Avenue des Hauts-Fourneaux, 4362, Esch/Alzette, Luxembourg
| | - Jean-Francois Hausman
- Research and Innovation Department, Luxembourg Institute of Science and Technology, 5 Avenue des Hauts-Fourneaux, 4362, Esch/Alzette, Luxembourg
| | - Stefano Del Duca
- Department of Biological, Geological and Environmental Sciences, University of Bologna, Via Irnerio 42, 40126, Bologna, Italy
- Interdepartmental Centre for Agri-Food Industrial Research, University of Bologna, Via Quinto Bucci 336, 47521, Cesena, Italy
| | - Giampiero Cai
- Department of Life Sciences, University of Siena, Via P.A. Mattioli 4, 53100, Siena, Italy
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16
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Jiang Y, Lu Q, Huang S. Functional non-equivalence of pollen ADF isovariants in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2022; 110:1068-1081. [PMID: 35233873 DOI: 10.1111/tpj.15723] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 02/24/2022] [Accepted: 02/26/2022] [Indexed: 06/14/2023]
Abstract
ADF/cofilin is a central regulator of actin dynamics. We previously demonstrated that two closely related Arabidopsis class IIa ADF isovariants, ADF7 and ADF10, are involved in the enhancement of actin turnover in pollen, but whether they have distinct functions remains unknown. Here, we further demonstrate that they exhibit distinct functions in regulating actin turnover both in vitro and in vivo. We found that ADF7 binds to ADP-G-actin with lower affinity, and severs and depolymerizes actin filaments less efficiently in vitro than ADF10. Accordingly, in pollen grains, ADF7 more extensively decorates actin filaments and is less freely distributed in the cytoplasm compared to ADF10. We further demonstrate that ADF7 and ADF10 show distinct intracellular localizations during pollen germination, and they have non-equivalent functions in promoting actin turnover in pollen. We thus propose that cooperation and labor division of ADF7 and ADF10 enable pollen cells to achieve exquisite control of the turnover of different actin structures to meet different cellular needs.
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Affiliation(s)
- Yuxiang Jiang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Qiaonan Lu
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Shanjin Huang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
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17
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Wasąg P, Suwińska A, Lenartowska M, Lenartowski R. RNAi-Mediated Knockdown of Calreticulin3a Impairs Pollen Tube Growth in Petunia. Int J Mol Sci 2022; 23:ijms23094987. [PMID: 35563382 PMCID: PMC9103332 DOI: 10.3390/ijms23094987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2022] [Revised: 04/14/2022] [Accepted: 04/26/2022] [Indexed: 02/05/2023] Open
Abstract
Pollen tube growth depends on several complex processes, including exo/endocytosis, cell wall biogenesis, intracellular transport, and cell signaling. Our previous results provided evidence that calreticulin (CRT)—a prominent calcium (Ca2+)-buffering molecular chaperone in the endoplasmic reticulum (ER) lumen—is involved in pollen tube formation and function. We previously cloned and characterized the CRT gene belonging to the CRT1/2 subgroup from Petunia hybrida (PhCRT1/2), and found that post-transcriptional silencing of PhCRT1/2 expression strongly impaired pollen tube growth in vitro. Here, we report cloning of a new PhCRT3a homolog; we identified the full-length cDNA sequence and described its molecular characteristics and phylogenetic relationships to other plant CRT3 genes. Using an RNA interference (RNAi) strategy, we found that knockdown of PhCRT3a gene expression caused numerous defects in the morphology and ultrastructure of cultivated pollen tubes, including disorganization of the actin cytoskeleton and loss of cytoplasmic zonation. Elongation of siPhCRT3a pollen tubes was disrupted, and some of them ruptured. Our present data provide the first evidence that PhCRT3a expression is required for normal pollen tube growth. Thus, we discuss relationships between diverse CRT isoforms in several interdependent processes driving the apical growth of the pollen tube, including actomyosin-dependent cytoplasmic streaming, organelle positioning, vesicle trafficking, and cell wall biogenesis.
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Affiliation(s)
- Piotr Wasąg
- Department of Cellular and Molecular Biology, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University in Torun, 87-100 Torun, Poland; (P.W.); (A.S.); (M.L.)
- Department of Biochemistry and Cell Biology, Faculty of Biological Sciences, Kazimierz Wielki University, 85-093 Bydgoszcz, Poland
| | - Anna Suwińska
- Department of Cellular and Molecular Biology, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University in Torun, 87-100 Torun, Poland; (P.W.); (A.S.); (M.L.)
- Centre for Modern Interdisciplinary Technologies, Nicolaus Copernicus University in Torun, 87-100 Torun, Poland
| | - Marta Lenartowska
- Department of Cellular and Molecular Biology, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University in Torun, 87-100 Torun, Poland; (P.W.); (A.S.); (M.L.)
- Centre for Modern Interdisciplinary Technologies, Nicolaus Copernicus University in Torun, 87-100 Torun, Poland
| | - Robert Lenartowski
- Department of Cellular and Molecular Biology, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University in Torun, 87-100 Torun, Poland; (P.W.); (A.S.); (M.L.)
- Centre for Modern Interdisciplinary Technologies, Nicolaus Copernicus University in Torun, 87-100 Torun, Poland
- Correspondence:
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18
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Ghifari AS, Teixeira PF, Kmiec B, Singh N, Glaser E, Murcha MW. The dual-targeted prolyl aminopeptidase PAP1 is involved in proline accumulation in response to stress and during pollen development. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:78-93. [PMID: 34460901 DOI: 10.1093/jxb/erab397] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 08/30/2021] [Indexed: 06/13/2023]
Abstract
Plant endosymbiotic organelles such as mitochondria and chloroplasts harbour a wide array of biochemical reactions. As a part of protein homeostasis to maintain organellar activity and stability, unwanted proteins and peptides need to be completely degraded in a stepwise mechanism termed the processing pathway, where at the last stage single amino acids are released by aminopeptidases. Here, we determined the molecular and physiological functions of a prolyl aminopeptidase homologue PAP1 (At2g14260) that is able to release N-terminal proline. Transcript analyses demonstrate that an alternative transcription start site gives rise to two alternative transcripts, generating two in-frame proteins PAP1.1 and PAP1.2. Subcellular localization studies revealed that the longer isoform PAP1.1, which contains a 51 residue N-terminal extension, is exclusively targeted to chloroplasts, while the truncated isoform PAP1.2 is located in the cytosol. Distinct expression patterns in different tissues and developmental stages were observed. Investigations into the physiological role of PAP1 using loss-of-function mutants revealed that PAP1 activity may be involved in proline homeostasis and accumulation, required for pollen development and tolerance to osmotic stress. Enzymatic activity, subcellular location, and expression patterns of PAP1 suggest a role in the chloroplastic peptide processing pathway and proline homeostasis.
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Affiliation(s)
- Abi S Ghifari
- School of Molecular Sciences, The University of Western Australia, Crawley, Perth WA, Australia
- ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, Crawley, Perth WA, Australia
| | - Pedro F Teixeira
- Department of Biochemistry and Biophysics, Arrhenius Laboratory for Natural Sciences, Stockholm University, Stockholm, Sweden
| | - Beata Kmiec
- Department of Biochemistry and Biophysics, Arrhenius Laboratory for Natural Sciences, Stockholm University, Stockholm, Sweden
| | - Neha Singh
- School of Molecular Sciences, The University of Western Australia, Crawley, Perth WA, Australia
- ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, Crawley, Perth WA, Australia
| | - Elzbieta Glaser
- Department of Biochemistry and Biophysics, Arrhenius Laboratory for Natural Sciences, Stockholm University, Stockholm, Sweden
| | - Monika W Murcha
- School of Molecular Sciences, The University of Western Australia, Crawley, Perth WA, Australia
- ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, Crawley, Perth WA, Australia
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19
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Westermann J. Two Is Company, but Four Is a Party-Challenges of Tetraploidization for Cell Wall Dynamics and Efficient Tip-Growth in Pollen. PLANTS (BASEL, SWITZERLAND) 2021; 10:plants10112382. [PMID: 34834745 PMCID: PMC8623246 DOI: 10.3390/plants10112382] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 11/01/2021] [Accepted: 11/03/2021] [Indexed: 05/27/2023]
Abstract
Some cells grow by an intricately coordinated process called tip-growth, which allows the formation of long tubular structures by a remarkable increase in cell surface-to-volume ratio and cell expansion across vast distances. On a broad evolutionary scale, tip-growth has been extraordinarily successful, as indicated by its recurrent 're-discovery' throughout evolutionary time in all major land plant taxa which allowed for the functional diversification of tip-growing cell types across gametophytic and sporophytic life-phases. All major land plant lineages have experienced (recurrent) polyploidization events and subsequent re-diploidization that may have positively contributed to plant adaptive evolutionary processes. How individual cells respond to genome-doubling on a shorter evolutionary scale has not been addressed as elaborately. Nevertheless, it is clear that when polyploids first form, they face numerous important challenges that must be overcome for lineages to persist. Evidence in the literature suggests that tip-growth is one of those processes. Here, I discuss the literature to present hypotheses about how polyploidization events may challenge efficient tip-growth and strategies which may overcome them: I first review the complex and multi-layered processes by which tip-growing cells maintain their cell wall integrity and steady growth. I will then discuss how they may be affected by the cellular changes that accompany genome-doubling. Finally, I will depict possible mechanisms polyploid plants may evolve to compensate for the effects caused by genome-doubling to regain diploid-like growth, particularly focusing on cell wall dynamics and the subcellular machinery they are controlled by.
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Affiliation(s)
- Jens Westermann
- Institute of Molecular Plant Biology, Department of Biology, ETH Zürich, Universitätsstrasse 2, 8092 Zürich, Switzerland
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20
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Tian X, Wang X, Li Y. Myosin XI-B is involved in the transport of vesicles and organelles in pollen tubes of Arabidopsis thaliana. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 108:1145-1161. [PMID: 34559914 DOI: 10.1111/tpj.15505] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 09/09/2021] [Accepted: 09/14/2021] [Indexed: 06/13/2023]
Abstract
The movement of organelles and vesicles in pollen tubes depends on F-actin. However, the molecular mechanism through which plant myosin XI drives the movement of organelles is still controversial, and the relationship between myosin XI and vesicle movement in pollen tubes is also unclear. In this study, we found that the siliques of the myosin xi-b/e mutant were obviously shorter than those of the wild-type (WT) and that the seed set of the mutant was severely deficient. The pollen tube growth of myosin xi-b/e was significantly inhibited both in vitro and in vivo. Fluorescence recovery after photobleaching showed that the velocity of vesicle movement in the pollen tube tip of the myosin xi-b/e mutant was lower than that of the WT. It was also found that peroxisome movement was significantly inhibited in the pollen tubes of the myosin xi-b/e mutant, while the velocities of the Golgi stack and mitochondrial movement decreased relatively less in the pollen tubes of the mutant. The endoplasmic reticulum streaming in the pollen tube shanks was not significantly different between the WT and the myosin xi-b/e mutant. In addition, we found that myosin XI-B-GFP colocalized obviously with vesicles and peroxisomes in the pollen tubes of Arabidopsis. Taken together, these results indicate that myosin XI-B may bind mainly to vesicles and peroxisomes, and drive their movement in pollen tubes. These results also suggest that the mechanism by which myosin XI drives organelle movement in plant cells may be evolutionarily conserved compared with other eukaryotic cells.
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Affiliation(s)
- Xiulin Tian
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Xingjuan Wang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Yan Li
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
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21
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MicroRNA Omics Analysis of Camellia sinesis Pollen Tubes in Response to Low-Temperature and Nitric Oxide. Biomolecules 2021; 11:biom11070930. [PMID: 34201466 PMCID: PMC8301950 DOI: 10.3390/biom11070930] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 06/20/2021] [Accepted: 06/21/2021] [Indexed: 12/21/2022] Open
Abstract
Nitric oxide (NO) as a momentous signal molecule participates in plant reproductive development and responds to various abiotic stresses. Here, the inhibitory effects of the NO-dominated signal network on the pollen tube growth of Camellia sinensis under low temperature (LT) were studied by microRNA (miRNA) omics analysis. The results showed that 77 and 71 differentially expressed miRNAs (DEMs) were induced by LT and NO treatment, respectively. Gene ontology (GO) analysis showed that DEM target genes related to microtubules and actin were enriched uniquely under LT treatment, while DEM target genes related to redox process were enriched uniquely under NO treatment. In addition, the target genes of miRNA co-regulated by LT and NO are only located on the cell membrane and cell wall, and most of them are enriched in metal ion binding and/or transport and cell wall organization. Furthermore, DEM and its target genes related to metal ion binding/transport, redox process, actin, cell wall organization and carbohydrate metabolism were identified and quantified by functional analysis and qRT-PCR. In conclusion, miRNA omics analysis provides a complex signal network regulated by NO-mediated miRNA, which changes cell structure and component distribution by adjusting Ca2+ gradient, thus affecting the polar growth of the C. sinensis pollen tube tip under LT.
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22
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Dell’Aglio E. A COG in the machine: how good Golgi makes good pollen. PLANT PHYSIOLOGY 2021; 186:201-203. [PMID: 33674832 PMCID: PMC8154076 DOI: 10.1093/plphys/kiab078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 02/13/2021] [Indexed: 06/12/2023]
Affiliation(s)
- Elisa Dell’Aglio
- Institut National des Sciences Appliquées de Lyon, 69100 Villeurbanne, France
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23
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Abstract
The plant cell wall is an extracellular matrix that envelopes cells, gives them structure and shape, constitutes the interface with symbionts, and defends plants against external biotic and abiotic stress factors. The assembly of this matrix is regulated and mediated by the cytoskeleton. Cytoskeletal elements define where new cell wall material is added and how fibrillar macromolecules are oriented in the wall. Inversely, the cytoskeleton is also key in the perception of mechanical cues generated by structural changes in the cell wall as well as the mediation of intracellular responses. We review the delivery processes of the cell wall precursors that are required for the cell wall assembly process and the structural continuity between the inside and the outside of the cell. We provide an overview of the different morphogenetic processes for which cell wall assembly is a crucial element and elaborate on relevant feedback mechanisms.
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24
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Lénárt J, Gere A, Causon T, Hann S, Dernovics M, Németh O, Hegedűs A, Halász J. LC-MS based metabolic fingerprinting of apricot pistils after self-compatible and self-incompatible pollinations. PLANT MOLECULAR BIOLOGY 2021; 105:435-447. [PMID: 33296063 PMCID: PMC7892686 DOI: 10.1007/s11103-020-01098-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 11/19/2020] [Indexed: 06/12/2023]
Abstract
KEY MESSAGE LC-MS based metabolomics approach revealed that putative metabolites other than flavonoids may significantly contribute to the sexual compatibility reactions in Prunus armeniaca. Possible mechanisms on related microtubule-stabilizing effects are provided. Identification of metabolites playing crucial roles in sexual incompatibility reactions in apricot (Prunus armeniaca L.) was the aim of the study. Metabolic fingerprints of self-compatible and self-incompatible apricot pistils were created using liquid chromatography coupled to time-of-flight mass spectrometry followed by untargeted compound search. Multivariate statistical analysis revealed 15 significant differential compounds among the total of 4006 and 1005 aligned metabolites in positive and negative ion modes, respectively. Total explained variance of 89.55% in principal component analysis (PCA) indicated high quality of differential expression analysis. The statistical analysis showed significant differences between genotypes and pollination time as well, which demonstrated high performance of the metabolic fingerprinting and revealed the presence of metabolites with significant influence on the self-incompatibility reactions. Finally, polyketide-based macrolides similar to peloruside A and a hydroxy sphingosine derivative are suggested to be significant differential metabolites in the experiment. These results indicate a strategy of pollen tubes to protect microtubules and avoid growth arrest involved in sexual incompatibility reactions of apricot.
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Affiliation(s)
- József Lénárt
- Department of Applied Chemistry, Faculty of Food Science, Szent István University, Villányi út 29-43, Budapest, 1118, Hungary
- Department of Genetics and Plant Breeding, Faculty of Horticultural Science, Szent István University, Ménesi út 44, Budapest, 1118, Hungary
| | - Attila Gere
- Department of Postharvest Sciences and Sensory Evaluation, Faculty of Food Science, Szent István University, Villányi út 29-43, 1118, Budapest, Hungary
| | - Tim Causon
- Institute of Analytical Chemistry, University of Natural Resources and Life Sciences, Muthgasse 18, 1190, Vienna, Austria
| | - Stephan Hann
- Institute of Analytical Chemistry, University of Natural Resources and Life Sciences, Muthgasse 18, 1190, Vienna, Austria
| | - Mihály Dernovics
- Department of Plant Physiology, Agricultural Institute, Centre for Agricultural Research, Brunszvik u. 2, Martonvásár, 2462, Hungary
| | - Olga Németh
- Department of Applied Chemistry, Faculty of Food Science, Szent István University, Villányi út 29-43, Budapest, 1118, Hungary
| | - Attila Hegedűs
- Department of Genetics and Plant Breeding, Faculty of Horticultural Science, Szent István University, Ménesi út 44, Budapest, 1118, Hungary
| | - Júlia Halász
- Department of Genetics and Plant Breeding, Faculty of Horticultural Science, Szent István University, Ménesi út 44, Budapest, 1118, Hungary.
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Han Y, Shi W, Tang Y, Zhao X, Du X, Sun S, Zhou W, Liu G. Ocean acidification increases polyspermy of a broadcast spawning bivalve species by hampering membrane depolarization and cortical granule exocytosis. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2021; 231:105740. [PMID: 33440272 DOI: 10.1016/j.aquatox.2020.105740] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 12/27/2020] [Accepted: 12/29/2020] [Indexed: 06/12/2023]
Abstract
Ensuring that oocytes are fertilized by a single sperm during broadcast spawning is crucial for the fertilization success of many marine invertebrates. Although the adverse impacts of ocean acidification (OA) on various marine species have been revealed in recent years, its impact on polyspermy and the underlying mechanisms involved remain largely unknown. Therefore, in the present study, the effect of OA on polyspermy risk was assessed in a broadcast spawning bivalve, Tegillarca granosa. In addition, the impacts of OA on the two polyspermy blocking processes, the fast block (membrane depolarization) and the permanent block (cortical reaction), were investigated. The results show that the exposure of oocytes to two future OA scenarios (pH 7.8 and pH 7.4) leads to significant increases in polyspermy risk, about 1.70 and 2.38 times higher than the control, respectively. The maximum change in the membrane potential during oocyte membrane depolarization markedly decreased to 15.79 % (pH 7.8) and 34.06 % (pH 7.4) of the control value. Moreover, the duration of oocyte membrane depolarization was significantly reduced to approximately 63.38 % (pH 7.8) and 21.91 % (pH 7.4) of the control. In addition, cortical granule exocytosis, as well as microfilament migration, were significantly arrested by OA treatment. Exposure to future OA scenarios also led to significant reductions in the ATP and Ca2+ content of the oocytes, which may explain the hampered polyspermy blocking. Overall, the present study suggests that OA may significantly increase polyspermy risk in T. granosa by inhibiting membrane depolarization and arresting cortical granule exocytosis.
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Affiliation(s)
- Yu Han
- College of Animal Sciences, Zhejiang University, Hangzhou, 310058, PR China
| | - Wei Shi
- College of Animal Sciences, Zhejiang University, Hangzhou, 310058, PR China
| | - Yu Tang
- College of Animal Sciences, Zhejiang University, Hangzhou, 310058, PR China
| | - Xinguo Zhao
- College of Animal Sciences, Zhejiang University, Hangzhou, 310058, PR China; Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, 266071, PR China
| | - Xueying Du
- College of Animal Sciences, Zhejiang University, Hangzhou, 310058, PR China
| | - Shuge Sun
- College of Animal Sciences, Zhejiang University, Hangzhou, 310058, PR China
| | - Weishang Zhou
- College of Animal Sciences, Zhejiang University, Hangzhou, 310058, PR China
| | - Guangxu Liu
- College of Animal Sciences, Zhejiang University, Hangzhou, 310058, PR China.
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26
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Breygina M, Klimenko E. ROS and Ions in Cell Signaling during Sexual Plant Reproduction. Int J Mol Sci 2020; 21:E9476. [PMID: 33322128 PMCID: PMC7764562 DOI: 10.3390/ijms21249476] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 12/09/2020] [Accepted: 12/10/2020] [Indexed: 12/30/2022] Open
Abstract
Pollen grain is a unique haploid organism characterized by two key physiological processes: activation of metabolism upon exiting dormancy and polar tube growth. In gymnosperms and flowering plants, these processes occur in different time frames and exhibit important features; identification of similarities and differences is still in the active phase. In angiosperms, the growth of male gametophyte is directed and controlled by its microenvironment, while in gymnosperms it is relatively autonomous. Recent reviews have detailed aspects of interaction between angiosperm female tissues and pollen such as interactions between peptides and their receptors; however, accumulated evidence suggests low-molecular communication, in particular, through ion exchange and ROS production, equally important for polar growth as well as for pollen germination. Recently, it became clear that ROS and ionic currents form a single regulatory module, since ROS production and the activity of ion transport systems are closely interrelated and form a feedback loop.
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Affiliation(s)
- Maria Breygina
- Department of Plant Physiology, Biological Faculty, Lomonosov Moscow State University, 119991 Moscow, Russia;
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27
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Xu Y, Huang S. Control of the Actin Cytoskeleton Within Apical and Subapical Regions of Pollen Tubes. Front Cell Dev Biol 2020; 8:614821. [PMID: 33344460 PMCID: PMC7744591 DOI: 10.3389/fcell.2020.614821] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 11/13/2020] [Indexed: 01/07/2023] Open
Abstract
In flowering plants, sexual reproduction involves a double fertilization event, which is facilitated by the delivery of two non-motile sperm cells to the ovule by the pollen tube. Pollen tube growth occurs exclusively at the tip and is extremely rapid. It strictly depends on an intact actin cytoskeleton, and is therefore an excellent model for uncovering the molecular mechanisms underlying dynamic actin cytoskeleton remodeling. There has been a long-term debate about the organization and dynamics of actin filaments within the apical and subapical regions of pollen tube tips. By combining state-of-the-art live-cell imaging with the usage of mutants which lack different actin-binding proteins, our understanding of the origin, spatial organization, dynamics and regulation of actin filaments within the pollen tube tip has greatly improved. In this review article, we will summarize the progress made in this area.
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Affiliation(s)
| | - Shanjin Huang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
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Çetinbaş-Genç A, Vardar F. Effect of methyl jasmonate on in-vitro pollen germination and tube elongation of Pinus nigra. PROTOPLASMA 2020; 257:1655-1665. [PMID: 32734410 DOI: 10.1007/s00709-020-01539-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 07/28/2020] [Indexed: 06/11/2023]
Abstract
The purpose of the main research was to investigate the effects of methyl jasmonate (MeJA) (0.05, 0.25, 0.5, and 2.5 mM) on the pollen germination and tube elongation of Pinus nigra. Total pollen germination rate increased after MeJA treatments while the most enhancement was observed at 0.05-mM MeJA. No germination was observed at 2.5-mM MeJA. Although the unipolar and bipolar germination were observed in all groups, no significant changes were observed in unipolar and bipolar pollen germination rates after MeJA treatments. Tube length increased only at 0.05-mM MeJA. Although branched tubes were observed in all groups, branched tube rate increased only at 0.05-mM MeJA. Although two branched, three branched, and consecutive branched tubes were observed in all groups, the most common branching type was two branched type in all groups. Although anisotropy of actin filaments in the shank and apex of unbranched tubes decreased after MeJA treatments, the most decrease was observed at 0.05-mM MeJA. Also, anisotropy of actin filaments in the shank and in pre-branching region of branched tubes decreased only at 0.25-mM MeJA. Anisotropy of both two apexes of a branched tube changed only at 0.25- and 0.5-mM MeJA. Callose accumulation in the apex of unbranched and branched tubes increased in parallel with the increase in MeJA concentration. However, more callose is accumulated in one apex than the other apex of a branched tube. In conclusion, MeJA affected the actin organization, changed the callose distribution, and altered the pollen tube growth of Pinus nigra.
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Affiliation(s)
- Aslıhan Çetinbaş-Genç
- Department of Biology, Marmara University, Göztepe Campus, Kadıköy, 34722, Istanbul, Turkey.
| | - Filiz Vardar
- Department of Biology, Marmara University, Göztepe Campus, Kadıköy, 34722, Istanbul, Turkey
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29
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Çetinbaş-Genç A, Cai G, Del Duca S. Treatment with spermidine alleviates the effects of concomitantly applied cold stress by modulating Ca 2+, pH and ROS homeostasis, actin filament organization and cell wall deposition in pollen tubes of Camellia sinensis. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2020; 156:578-590. [PMID: 33065378 DOI: 10.1016/j.plaphy.2020.10.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Accepted: 10/08/2020] [Indexed: 06/11/2023]
Abstract
The aim of the current study was to examine the effect of spermidine treatment concomitant with cold stress on the elongation of Camellia sinensis pollen tube. When exogenous spermidine (0.05 mM) was applied concomitantly with cold stress, pollen germination rate and pollen tube length were significantly increased in comparison with cold stressed pollen tubes. In addition, spermidine treatment concomitantly with cold stress reduced pollen tube abnormalities induced by cold stress. Besides, cold-induced disorganizations of actin filaments were ameliorated after spermidine treatment along with cold stress because anisotropy levels of actin filaments in shank and apex of pollen tubes decreased. Changes in cold-induced callose distribution in the pollen tube cell wall were partially recovered after spermidine/cold stress treatment. Other cold-induced effects (decrease in Ca2+ content, reduction of pH gradient, accumulation of ROS) were reverted to adequate levels after spermidine treatment in conjunction with cold stress, indicating that pollen tubes are able to cope with stress. Thus, spermidine treatment reorganized the growth pattern of pollen tubes by modulating Ca2+ and ROS homeostasis, actin cytoskeleton organization, and cell wall deposition in Camellia sinensis pollen tubes under cold stress.
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Affiliation(s)
- Aslıhan Çetinbaş-Genç
- Department of Biology, Marmara University, Göztepe Campus, Kadıköy, 34722, Istanbul, Turkey.
| | - Giampiero Cai
- Department of Life Sciences, University of Siena, Via Mattioli 4, 53100, Siena, Italy.
| | - Stefano Del Duca
- Department of Biological, Geological and Environmental Sciences, University of Bologna, Via Irnerio 42, 40126, Bologna, Italy.
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30
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Wolgemuth CW, Sun SX. Active random forces can drive differential cellular positioning and enhance motor-driven transport. Mol Biol Cell 2020; 31:2283-2288. [PMID: 32726176 PMCID: PMC7550702 DOI: 10.1091/mbc.e19-11-0629] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Cells are remarkable machines capable of performing an exquisite range of functions, many of which depend crucially on the activity of molecular motors that generate forces. Recent experiments have shown that intracellular random movements are not solely thermal in nature but also arise from stochasticity in the forces from these molecular motors. Here we consider the effects of these nonthermal random forces. We show that stochastic motor force not only enhances diffusion but also leads to size-dependent transport of objects that depends on the local density of the cytoskeletal filaments on which motors operate. As a consequence, we find that objects that are larger than the mesh size of the cytoskeleton should be attracted to regions of high cytoskeletal density, while objects that are smaller than the mesh size will preferentially avoid these regions. These results suggest a mechanism for size-based organelle positioning and also suggest that motor-driven random forces can additionally enhance motor-driven transport.
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Affiliation(s)
- Charles W Wolgemuth
- Johns Hopkins Physical Sciences-Oncology Center, Johns Hopkins University, Baltimore, MD 21218.,Departments of Physics and Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721
| | - Sean X Sun
- Johns Hopkins Physical Sciences-Oncology Center, Johns Hopkins University, Baltimore, MD 21218.,Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218
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Scholz P, Anstatt J, Krawczyk HE, Ischebeck T. Signalling Pinpointed to the Tip: The Complex Regulatory Network That Allows Pollen Tube Growth. PLANTS (BASEL, SWITZERLAND) 2020; 9:E1098. [PMID: 32859043 PMCID: PMC7569787 DOI: 10.3390/plants9091098] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 08/18/2020] [Accepted: 08/23/2020] [Indexed: 12/13/2022]
Abstract
Plants display a complex life cycle, alternating between haploid and diploid generations. During fertilisation, the haploid sperm cells are delivered to the female gametophyte by pollen tubes, specialised structures elongating by tip growth, which is based on an equilibrium between cell wall-reinforcing processes and turgor-driven expansion. One important factor of this equilibrium is the rate of pectin secretion mediated and regulated by factors including the exocyst complex and small G proteins. Critically important are also non-proteinaceous molecules comprising protons, calcium ions, reactive oxygen species (ROS), and signalling lipids. Among the latter, phosphatidylinositol 4,5-bisphosphate and the kinases involved in its formation have been assigned important functions. The negatively charged headgroup of this lipid serves as an interaction point at the apical plasma membrane for partners such as the exocyst complex, thereby polarising the cell and its secretion processes. Another important signalling lipid is phosphatidic acid (PA), that can either be formed by the combination of phospholipases C and diacylglycerol kinases or by phospholipases D. It further fine-tunes pollen tube growth, for example by regulating ROS formation. How the individual signalling cues are intertwined or how external guidance cues are integrated to facilitate directional growth remain open questions.
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Affiliation(s)
- Patricia Scholz
- Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences and Goettingen Center for Molecular Biosciences (GZMB), University of Goettingen, Justus-von-Liebig Weg 11, D-37077 Goettingen, Germany; (J.A.); (H.E.K.)
| | | | | | - Till Ischebeck
- Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences and Goettingen Center for Molecular Biosciences (GZMB), University of Goettingen, Justus-von-Liebig Weg 11, D-37077 Goettingen, Germany; (J.A.); (H.E.K.)
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32
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Williams JH, Oliveira PE. For things to stay the same, things must change: polyploidy and pollen tube growth rates. ANNALS OF BOTANY 2020; 125:925-935. [PMID: 31957784 PMCID: PMC7218811 DOI: 10.1093/aob/mcaa007] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 01/17/2020] [Indexed: 05/13/2023]
Abstract
BACKGROUND AND AIMS Pollen tube growth rate (PTGR) is an important single-cell performance trait that may evolve rapidly under haploid selection. Angiosperms have experienced repeated cycles of polyploidy (whole genome duplication), and polyploidy has cell-level phenotypic consequences arising from increased bulk DNA amount and numbers of genes and their interactions. We sought to understand potential effects of polyploidy on several underlying determinants of PTGR - pollen tube dimensions and construction rates - by comparing diploid-polyploid near-relatives in Betula (Betulaceae) and Handroanthus (Bignoniaceae). METHODS We performed intraspecific, outcrossed hand-pollinations on pairs of flowers. In one flower, PTGR was calculated from the longest pollen tube per time of tube elongation. In the other, styles were embedded in glycol methacrylate, serial-sectioned in transverse orientation, stained and viewed at 1000× to measure tube wall thicknesses (W) and circumferences (C). Volumetric growth rate (VGR) and wall production rate (WPR) were then calculated for each tube by multiplying cross-sectional tube area (πr2) or wall area (W × C), by the mean PTGR of each maternal replicate respectively. KEY RESULTS In Betula and Handroanthus, the hexaploid species had significantly wider pollen tubes (13 and 25 %, respectively) and significantly higher WPRs (22 and 18 %, respectively) than their diploid congeners. PTGRs were not significantly different in both pairs, even though wider polyploid tubes were predicted to decrease PTGRs by 16 and 20 %, respectively. CONCLUSIONS The larger tube sizes of polyploids imposed a substantial materials cost on PTGR, but polyploids also exhibited higher VGRs and WPRs, probably reflecting the evolution of increased metabolic activity. Recurrent cycles of polyploidy followed by genome reorganization may have been important for the evolution of fast PTGRs in angiosperms, involving a complex interplay between correlated changes in ploidy level, genome size, cell size and pollen tube energetics.
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Affiliation(s)
- Joseph H Williams
- Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN, USA
| | - Paulo E Oliveira
- Instituto de Biologia, Universidade Federal de Uberlândia, Campus Umuarama, Uberlândia, Minas Gerais 38405-320 Brazil
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Guo J, Yang Z. Exocytosis and endocytosis: coordinating and fine-tuning the polar tip growth domain in pollen tubes. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:2428-2438. [PMID: 32173729 PMCID: PMC7178420 DOI: 10.1093/jxb/eraa134] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Accepted: 03/11/2020] [Indexed: 05/06/2023]
Abstract
Pollen tubes rapidly elongate, penetrate, and navigate through multiple female tissues to reach ovules for sperm delivery by utilizing a specialized form of polar growth known as tip growth. This process requires a battery of cellular activities differentially occurring at the apical growing region of the plasma membrane (PM), such as the differential cellular signaling involving calcium (Ca2+), phospholipids, and ROP-type Rho GTPases, fluctuation of ions and pH, exocytosis and endocytosis, and cell wall construction and remodeling. There is an emerging understanding of how at least some of these activities are coordinated and/or interconnected. The apical active ROP modulates exocytosis to the cell apex for PM and cell wall expansion differentially occurring at the tip. The differentiation of the cell wall involves at least the preferential distribution of deformable pectin polymers to the apex and non-deformable pectin polymers to the shank of pollen tubes, facilitating the apical cell expansion driven by high internal turgor pressure. Recent studies have generated inroads into how the ROP GTPase-based intracellular signaling is coordinated spatiotemporally with the external wall mechanics to maintain the tubular cell shape and how the apical cell wall mechanics are regulated to allow rapid tip growth while maintaining the cell wall integrity under the turgor pressure. Evidence suggests that exocytosis and endocytosis play crucial but distinct roles in this spatiotemporal coordination. In this review, we summarize recent advances in the regulation and coordination of the differential pectin distribution and the apical domain of active ROP by exocytosis and endocytosis in pollen tubes.
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Affiliation(s)
- Jingzhe Guo
- FAFU-UCR Joint Center for Horticultural Biology and Metabolomics, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
- Department of Botany and Plant Sciences and Institute for Integrative Genome Biology, University of California, Riverside, CA, USA
| | - Zhenbiao Yang
- Department of Botany and Plant Sciences and Institute for Integrative Genome Biology, University of California, Riverside, CA, USA
- Correspondence:
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Çetinbaş-Genç A. Putrescine modifies the pollen tube growth of tea (Camellia sinensis) by affecting actin organization and cell wall structure. PROTOPLASMA 2020; 257:89-101. [PMID: 31342152 DOI: 10.1007/s00709-019-01422-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Accepted: 07/17/2019] [Indexed: 06/10/2023]
Abstract
The aim of the current study was to examine the effect of different exogenous putrescine concentrations (200, 400, 600, and 800 μM) on the tea pollen performance. It was shown that putrescine has a dose-dependent effect on pollen performance. Results exhibited that pollen germination and tube elongation were induced by 200 and 400 μM putrescine treatment, especially, 400 μM putrescine-enhanced pollen performance. However, pollen performance was inhibited by higher concentrations of putrescine. Putrescine concentrations above 400 μM changed the actin filament distribution in pollen tubes by affecting the distribution of sucrose synthase enzyme. Alterations of the distribution on sucrose synthase enzyme also caused the alterations in the dispersion of cellulose and callose in the cell wall, and morphological alterations such as balloon-shaped and snake-shaped pollen tube tip accompanied them. Moreover, putrescine concentrations above 400 μM caused a decrease of ROS level in apex and led to chromatin condensation of the generative nucleus. In conclusion, exogenous putrescine application can be used as a pollen performance enhancer at low concentrations while the high concentrations cause adverse effects reducing fertilization success.
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Affiliation(s)
- Aslıhan Çetinbaş-Genç
- Department of Biology, Marmara University, Göztepe Campus, Kadıköy, 34722, Istanbul, Turkey.
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35
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Qian D, Xiang Y. Actin Cytoskeleton as Actor in Upstream and Downstream of Calcium Signaling in Plant Cells. Int J Mol Sci 2019; 20:ijms20061403. [PMID: 30897737 PMCID: PMC6471457 DOI: 10.3390/ijms20061403] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 03/14/2019] [Accepted: 03/15/2019] [Indexed: 01/04/2023] Open
Abstract
In plant cells, calcium (Ca2+) serves as a versatile intracellular messenger, participating in several fundamental and important biological processes. Recent studies have shown that the actin cytoskeleton is not only an upstream regulator of Ca2+ signaling, but also a downstream regulator. Ca2+ has been shown to regulates actin dynamics and rearrangements via different mechanisms in plants, and on this basis, the upstream signaling encoded within the Ca2+ transient can be decoded. Moreover, actin dynamics have also been proposed to act as an upstream of Ca2+, adjust Ca2+ oscillations, and establish cytosolic Ca2+ ([Ca2+]cyt) gradients in plant cells. In the current review, we focus on the advances in uncovering the relationship between the actin cytoskeleton and calcium in plant cells and summarize our current understanding of this relationship.
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Affiliation(s)
- Dong Qian
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China.
| | - Yun Xiang
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China.
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36
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Fang KF, Du BS, Zhang Q, Xing Y, Cao QQ, Qin L. Boron deficiency alters cytosolic Ca 2+ concentration and affects the cell wall components of pollen tubes in Malus domestica. PLANT BIOLOGY (STUTTGART, GERMANY) 2019; 21:343-351. [PMID: 30444945 DOI: 10.1111/plb.12941] [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: 09/05/2018] [Accepted: 11/13/2018] [Indexed: 06/09/2023]
Abstract
Boron (B) is essential for normal plant growth, including pollen tube growth. B deficiency influences various physiological and metabolic processes in plants. However, the underlying mechanism of B deficiency in pollen tube growth is not sufficiently understood. In the present research, the influence of B deficiency on apple (Malus domestica) pollen tube growth was studied and the possible regulatory mechanism evaluated. Apple pollen grains were cultured under different concentrations of B. Scanning ion-selective electrode technique, fluorescence labelling and Fourier-transform infrared (FTIR) analysis were used to detect calcium ion flux, cytosolic Ca2+ concentration ([Ca2+ ]cyt), actin filaments and cell wall components of pollen tubes. B deficiency inhibited apple pollen germination and induced retardation of tube growth. B deficiency increased extracellular Ca2+ influx and thus led to increased [Ca2+ ]cyt in the pollen tube tip. In addition, B deficiency modified actin filament arrangement at the pollen tube apex. B deficiency also altered the deposition of pollen tube wall components. Clear differences were not observed in the distribution patterns of cellulose and callose between control and B deficiency treated pollen tubes. However, B deficiency affected distribution patterns of pectin and arabinogalactan proteins (AGP). Clear ring-like signals of pectins and AGP on control pollen tubes varied according to B deficiency. B deficiency further decreased acid pectins, esterified pectins and AGP content at the tip of the pollen tube, which were supported by changes in chemical composition of the tube walls. B appears to have an active role in pollen tube growth by affecting [Ca2+ ]cyt, actin filament assembly and pectin and AGP deposition in the pollen tube. These findings provide valuable information that enhances our current understanding of the mechanism regulating pollen tube growth.
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Affiliation(s)
- K F Fang
- College of Landscape Architecture, Beijing University of Agriculture, Beijing, China
- Beijing Collaborative Innovation Center for Eco-environmental Improvement with Forestry and Fruit Trees, Beijing, China
| | - B S Du
- College of Landscape Architecture, Beijing University of Agriculture, Beijing, China
| | - Q Zhang
- Beijing Collaborative Innovation Center for Eco-environmental Improvement with Forestry and Fruit Trees, Beijing, China
- Key Laboratory for Agricultural Application and New Technique, College of Plant Science and Technology, Beijing University of Agriculture, Beijing, China
| | - Y Xing
- Beijing Collaborative Innovation Center for Eco-environmental Improvement with Forestry and Fruit Trees, Beijing, China
- Key Laboratory for Agricultural Application and New Technique, College of Plant Science and Technology, Beijing University of Agriculture, Beijing, China
| | - Q Q Cao
- Beijing Collaborative Innovation Center for Eco-environmental Improvement with Forestry and Fruit Trees, Beijing, China
- College of Biological Science and Engineering, Beijing University of Agriculture, Beijing, China
| | - L Qin
- Beijing Collaborative Innovation Center for Eco-environmental Improvement with Forestry and Fruit Trees, Beijing, China
- Key Laboratory for Agricultural Application and New Technique, College of Plant Science and Technology, Beijing University of Agriculture, Beijing, China
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37
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Del Duca S, Aloisi I, Parrotta L, Cai G. Cytoskeleton, Transglutaminase and Gametophytic Self-Incompatibility in the Malinae (Rosaceae). Int J Mol Sci 2019; 20:ijms20010209. [PMID: 30626063 PMCID: PMC6337636 DOI: 10.3390/ijms20010209] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 12/21/2018] [Accepted: 01/04/2019] [Indexed: 12/14/2022] Open
Abstract
Self-incompatibility (SI) is a complex process, one out of several mechanisms that prevent plants from self-fertilizing to maintain and increase the genetic variability. This process leads to the rejection of the male gametophyte and requires the co-participation of numerous molecules. Plants have evolved two distinct SI systems, the sporophytic (SSI) and the gametophytic (GSI) systems. The two SI systems are markedly characterized by different genes and proteins and each single system can also be divided into distinct subgroups; whatever the mechanism, the purpose is the same, i.e., to prevent self-fertilization. In Malinae, a subtribe in the Rosaceae family, i.e., Pyrus communis and Malus domestica, the GSI requires the production of female determinants, known as S-RNases, which penetrate the pollen tube to interact with the male determinants. Beyond this, the penetration of S-RNase into the pollen tube triggers a series of responses involving membrane proteins, such as phospholipases, intracellular variations of cytoplasmic Ca2+, production of reactive oxygen species (ROS) and altered enzymatic activities, such as that of transglutaminase (TGase). TGases are widespread enzymes that catalyze the post-translational conjugation of polyamines (PAs) to different protein targets and/or the cross-linking of substrate proteins leading to the formation of cross-linked products with high molecular mass. When actin and tubulin are the substrates, this destabilizes the cytoskeleton and inhibits the pollen-tube's growth process. In this review, we will summarize the current knowledge of the relationship between S-RNase penetration, TGase activity and cytoskeleton function during GSI in the Malinae.
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Affiliation(s)
- Stefano Del Duca
- Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Università di Bologna, Via Irnerio 42, 40126 Bologna, Italy.
| | - Iris Aloisi
- Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Università di Bologna, Via Irnerio 42, 40126 Bologna, Italy.
| | - Luigi Parrotta
- Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Università di Bologna, Via Irnerio 42, 40126 Bologna, Italy.
- Dipartimento di Scienze della Vita, Università di Siena, Via Mattioli 4, 53100 Siena, Italy.
| | - Giampiero Cai
- Dipartimento di Scienze della Vita, Università di Siena, Via Mattioli 4, 53100 Siena, Italy.
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Quantitative Analysis of Tip Growth, Phototropic Responses, and Other Blue Light-Dependent Photoresponses of Vaucheria. Methods Mol Biol 2019; 1924:83-120. [PMID: 30694469 DOI: 10.1007/978-1-4939-9015-3_8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The coenocytic tip-growing alga Vaucheria exhibits positive and negative phototropism, apical expansion, polarotropism, and branch induction from the illuminated region of the cell, all of which are caused by blue light. The bending response of Vaucheria is a blue light-mediated growth response. Differently from diffuse-growing cells or organs, the apical hemispherical dome of the Vaucheria cell is the site of not only maximum growth activity but also the site of blue light perception. Thence the phototropic response is initiated by the bulging mechanism: that is, a quick shift of the growth center to the adjacent subapical flank region. Since tip growth is driven by localized exocytosis, both phototropic bending and branch induction are considered to be closely related blue light-responses. Here I describe first how to prepare a highly useful culture medium for most freshwater algae, to establish unialgal and axenic culture of Vaucheria, and then describe several simple illumination systems using ordinary and/or inverted microscopes for the measurements of tip growth and for analyses of phototropism, polarotropism, and blue light-induced branching. Brief information is also included concerning the nature and function of aureochrome, the newly discovered, ochrophyte-specific blue light receptor. Aureochrome mediates blue light-induced branching, but its role in the phototropic response is still not elucidated.
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Zhang S, Wang C, Xie M, Liu J, Kong Z, Su H. Actin Bundles in The Pollen Tube. Int J Mol Sci 2018; 19:ijms19123710. [PMID: 30469514 PMCID: PMC6321563 DOI: 10.3390/ijms19123710] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Revised: 11/18/2018] [Accepted: 11/19/2018] [Indexed: 12/31/2022] Open
Abstract
The angiosperm pollen tube delivers two sperm cells into the embryo sac through a unique growth strategy, named tip growth, to accomplish fertilization. A great deal of experiments have demonstrated that actin bundles play a pivotal role in pollen tube tip growth. There are two distinct actin bundle populations in pollen tubes: the long, rather thick actin bundles in the shank and the short, highly dynamic bundles near the apex. With the development of imaging techniques over the last decade, great breakthroughs have been made in understanding the function of actin bundles in pollen tubes, especially short subapical actin bundles. Here, we tried to draw an overall picture of the architecture, functions and underlying regulation mechanism of actin bundles in plant pollen tubes.
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Affiliation(s)
- Shujuan Zhang
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education College of Life Science, Northwest University, Xi'an 710069, China.
| | - Chunbo Wang
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education College of Life Science, Northwest University, Xi'an 710069, China.
| | - Min Xie
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education College of Life Science, Northwest University, Xi'an 710069, China.
| | - Jinyu Liu
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education College of Life Science, Northwest University, Xi'an 710069, China.
| | - Zhe Kong
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education College of Life Science, Northwest University, Xi'an 710069, China.
| | - Hui Su
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education College of Life Science, Northwest University, Xi'an 710069, China.
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Lipchinsky A. Electromechanics of polarized cell growth. Biosystems 2018; 173:114-132. [PMID: 30300677 DOI: 10.1016/j.biosystems.2018.10.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 09/30/2018] [Accepted: 10/04/2018] [Indexed: 10/28/2022]
Abstract
One of the most challenging questions in cell and developmental biology is how molecular signals are translated into mechanical forces that ultimately drive cell growth and motility. Despite an impressive body of literature demonstrating the importance of cytoskeletal and motor proteins as well as osmotic stresses for cell developmental mechanics, a host of dissenting evidence strongly suggests that these factors per se cannot explain growth mechanics even at the level of a single tip-growing cell. The present study addresses this issue by exploring fundamental interrelations between electrical and mechanical fields operating in cells. In the first instance, we employ a simplified but instructive model of a quiescent cell to demonstrate that even in a quasi-equilibrium state, ion transport processes are conditioned principally by mechanical tenets. Then we inquire into the electromechanical conjugacy in growing pollen tubes as biologically relevant and physically tractable developmental systems owing to their extensively characterized growth-associated ionic fluxes and strikingly polarized growth and morphology. A comprehensive analysis of the multifold stress pattern in the growing apices of pollen tubes suggests that tip-focused ionic fluxes passing through the polyelectrolyte-rich apical cytoplasm give rise to electrokinetic flows that actualize otherwise isotropic intracellular turgor into anisotropic stress field. The stress anisotropy can be then imparted from the apical cytoplasm to the abutting frontal cell wall to induce its local extension and directional cell growth. Converging lines of evidence explored in the concluding sections attest that tip-focused ionic fluxes and associated interfacial transport phenomena are not specific for pollen tubes but are also employed by a vast variety of algal, plant, fungal and animal cells, rendering their cytoplasmic stress fields essentially anisotropic and ultimately instrumental in cell shaping, growth and motility.
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Affiliation(s)
- Andrei Lipchinsky
- Department of Plant Physiology and Biochemistry, St. Petersburg State University, 7/9 Universitetskaya nab., St. Petersburg, 199034, Russia.
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Perico C, Sparkes I. Plant organelle dynamics: cytoskeletal control and membrane contact sites. THE NEW PHYTOLOGIST 2018; 220:381-394. [PMID: 30078196 DOI: 10.1111/nph.15365] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Accepted: 06/10/2018] [Indexed: 05/22/2023]
Abstract
Contents Summary 381 I. Introduction 381 II. Basic movement characteristics 382 III. Actin and associated motors, myosins, play a primary role in plant organelle movement and positioning 382 IV. Mechanisms of myosin recruitment: a tightly regulated system? 384 V. Microtubules, associated motors and interplay with actin 386 VI. Role of organelle interactions: tales of tethers 387 VII. Summary model to describe organelle movement in higher plants 390 VIII. Why is organelle movement important? 390 IX. Conclusions and future perspectives 391 Acknowledgements 391 References 391 SUMMARY: Organelle movement and positioning are correlated with plant growth and development. Movement characteristics are seemingly erratic yet respond to external stimuli including pathogens and light. Given these clear correlations, we still do not understand the specific roles that movement plays in these processes. There are few exceptions including organelle inheritance during cell division and photorelocation of chloroplasts to prevent photodamage. The molecular and biophysical components that drive movement can be broken down into cytoskeletal components, motor proteins and tethers, which allow organelles to physically interact with one another. Our understanding of these components and concepts has exploded over the past decade, with recent technological advances allowing an even more in-depth profiling. Here, we provide an overview of the cytoskeletal and tethering components and discuss the mechanisms behind organelle movement in higher plants.
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Affiliation(s)
- Chiara Perico
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol, BS8 1TQ, UK
| | - Imogen Sparkes
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol, BS8 1TQ, UK
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Parrotta L, Faleri C, Del Duca S, Cai G. Depletion of sucrose induces changes in the tip growth mechanism of tobacco pollen tubes. ANNALS OF BOTANY 2018; 122:23-43. [PMID: 29659664 PMCID: PMC6025209 DOI: 10.1093/aob/mcy043] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Accepted: 03/09/2018] [Indexed: 05/24/2023]
Abstract
Background and Aims Pollen tubes are rapidly growing, photosynthetically inactive cells that need high rates of energy to support growth. Energy can derive from internal and external storage sources. The lack of carbon sources can cause various problems during pollen tube growth, which in turn could affect the reproduction of plants. Methods We analysed the effects of energy deficiency on the development of Nicotiana tabacum pollen tubes by replacing sucrose with glycerol in the growth medium. We focused on cell growth and related processes, such as metabolite composition and cell wall synthesis. Key Results We found that the lack of sucrose affects pollen germination and pollen tube length during a specific growth period. Both sugar metabolism and ATP concentration were affected by sucrose shortage when pollen tubes were grown in glycerol-based media; this was related to decreases in the concentrations of glucose, fructose and UDP-glucose. The intracellular pH and ROS levels also showed a different distribution in pollen tubes grown in sucrose-depleted media. Changes were also observed at the cell wall level, particularly in the content and distribution of two enzymes related to cell wall synthesis (sucrose synthase and callose synthase). Furthermore, both callose and newly secreted cell wall material (mainly pectins) showed an altered distribution corresponding to the lack of oscillatory growth in pollen tubes. Growth in glycerol-based media also temporarily affected the movement of generative cells and, in parallel, the deposition of callose plugs. Conclusion Pollen tubes represent an ideal model system for studying metabolic pathways during the growth of plant cells. In our study, we found evidence that glycerol, a less energetic source for cell growth than sucrose, causes critical changes in cell wall deposition. The evidence that different aspects of pollen tube growth are affected is an indication that pollen tubes adapt to metabolic stress.
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Affiliation(s)
- Luigi Parrotta
- Dipartimento Scienze della Vita, Università di Siena, Siena, Italy
| | - Claudia Faleri
- Dipartimento Scienze della Vita, Università di Siena, Siena, Italy
| | - Stefano Del Duca
- Dipartimento Scienze Biologiche, Geologiche e Ambientali, Università di Bologna, Bologna, Italy
| | - Giampiero Cai
- Dipartimento Scienze della Vita, Università di Siena, Siena, Italy
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Kumar AS, Park E, Nedo A, Alqarni A, Ren L, Hoban K, Modla S, McDonald JH, Kambhamettu C, Dinesh-Kumar SP, Caplan JL. Stromule extension along microtubules coordinated with actin-mediated anchoring guides perinuclear chloroplast movement during innate immunity. eLife 2018; 7:e23625. [PMID: 29338837 PMCID: PMC5815851 DOI: 10.7554/elife.23625] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Accepted: 01/16/2018] [Indexed: 12/21/2022] Open
Abstract
Dynamic tubular extensions from chloroplasts called stromules have recently been shown to connect with nuclei and function during innate immunity. We demonstrate that stromules extend along microtubules (MTs) and MT organization directly affects stromule dynamics since stabilization of MTs chemically or genetically increases stromule numbers and length. Although actin filaments (AFs) are not required for stromule extension, they provide anchor points for stromules. Interestingly, there is a strong correlation between the direction of stromules from chloroplasts and the direction of chloroplast movement. Stromule-directed chloroplast movement was observed in steady-state conditions without immune induction, suggesting it is a general function of stromules in epidermal cells. Our results show that MTs and AFs may facilitate perinuclear clustering of chloroplasts during an innate immune response. We propose a model in which stromules extend along MTs and connect to AF anchor points surrounding nuclei, facilitating stromule-directed movement of chloroplasts to nuclei during innate immunity.
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Affiliation(s)
| | - Eunsook Park
- Department of Plant Biology, College of Biological SciencesUniversity of California, DavisDavisUnited States
- The Genome Center, College of Biological SciencesUniversity of California, DavisDavisUnited States
| | - Alexander Nedo
- Delaware Biotechnology InstituteUniversity of DelawareNewarkUnited States
- Department of Biological Sciences, College of Arts and SciencesUniversity of DelawareNewarkUnited States
| | - Ali Alqarni
- Delaware Biotechnology InstituteUniversity of DelawareNewarkUnited States
- Department of Biological Sciences, College of Arts and SciencesUniversity of DelawareNewarkUnited States
- Department of Plant and Soil Sciences, College of Agriculture and Natural ResourcesUniversity of DelawareNewarkUnited States
| | - Li Ren
- Department of Plant and Soil Sciences, College of Agriculture and Natural ResourcesUniversity of DelawareNewarkUnited States
| | - Kyle Hoban
- Delaware Biotechnology InstituteUniversity of DelawareNewarkUnited States
- Department of Biological Sciences, College of Arts and SciencesUniversity of DelawareNewarkUnited States
| | - Shannon Modla
- Delaware Biotechnology InstituteUniversity of DelawareNewarkUnited States
| | - John H McDonald
- Department of Biological Sciences, College of Arts and SciencesUniversity of DelawareNewarkUnited States
| | - Chandra Kambhamettu
- Department of Plant and Soil Sciences, College of Agriculture and Natural ResourcesUniversity of DelawareNewarkUnited States
- Department of Computer and Information Sciences, College of EngineeringUniversity of DelawareNewarkUnited States
| | - Savithramma P Dinesh-Kumar
- Department of Plant Biology, College of Biological SciencesUniversity of California, DavisDavisUnited States
- The Genome Center, College of Biological SciencesUniversity of California, DavisDavisUnited States
| | - Jeffrey Lewis Caplan
- Delaware Biotechnology InstituteUniversity of DelawareNewarkUnited States
- Department of Biological Sciences, College of Arts and SciencesUniversity of DelawareNewarkUnited States
- Department of Plant and Soil Sciences, College of Agriculture and Natural ResourcesUniversity of DelawareNewarkUnited States
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Jia H, Yang J, Liesche J, Liu X, Hu Y, Si W, Guo J, Li J. Ethylene promotes pollen tube growth by affecting actin filament organization via the cGMP-dependent pathway in Arabidopsis thaliana. PROTOPLASMA 2018; 255:273-284. [PMID: 28864968 DOI: 10.1007/s00709-017-1158-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 08/23/2017] [Indexed: 06/07/2023]
Abstract
Ethylene and cGMP are key regulators of plant developmental processes. In this study, we demonstrate that ethylene or cGMP promote pollen tube growth in a dose-dependent manner. The etr1-1 mutant was found to be insensitive to ethylene with regard to pollen tube growth, while the growth-promoting effect of ethylene in etr2-2, ein4-4, or ein4-7 did not change, suggesting that ethylene signaling was mainly perceived by ETR1. However, the function of cGMP was not inhibited in etr1-1 and pollen tubes became insensitive to ethylene when the endogenous cGMP level was artificially decreased. This shows that cGMP is necessary for the control of pollen tube growth and that it might be a downstream component of ETR1 in the ethylene signaling pathway. Our study also found that ethylene or cGMP increase the actin bundles and elevated the percentage of relative amount of F-actin, while removal of cGMP decreased actin bundles abundance and altered the ratio of F-actin in the tip and base regions of pollen tubes. In conclusion, our data suggests that ethylene functions as the upstream signal of cGMP, and that both signals promote pollen germination and tube growth by regulating F-actin, which is essential for vesicular transport and cytoplasmic streaming.
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Affiliation(s)
- Honglei Jia
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China
- School of Environmental Science and Engineering, Shaanxi University of Science & Technology, Xi'an, Shaanxi, 710021, China
| | - Jun Yang
- School of Environmental Science and Engineering, Shaanxi University of Science & Technology, Xi'an, Shaanxi, 710021, China
| | - Johannes Liesche
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Xin Liu
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Yanfeng Hu
- Key Laboratory of Mollisols Agroecology, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Nangang District, Harbin, 150000, China
| | - Wantong Si
- Inner Mongolia Key Laboratory of Biomass-Energy Conversion, Inner Mongolia University of Science and Technology, Neimenggu, Baotou, 014010, China
| | - Junkang Guo
- School of Environmental Science and Engineering, Shaanxi University of Science & Technology, Xi'an, Shaanxi, 710021, China
| | - Jisheng Li
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China.
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Goring DR. Exocyst, exosomes, and autophagy in the regulation of Brassicaceae pollen-stigma interactions. JOURNAL OF EXPERIMENTAL BOTANY 2017; 69:69-78. [PMID: 29036428 DOI: 10.1093/jxb/erx340] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Brassicaceae pollen-stigma interactions have been extensively studied in Brassica and Arabidopsis species to identify cellular events triggered in the stigmatic papillae by pollen contact. Compatible pollinations are linked to the activation of basal cellular responses in the stigmatic papillae, which include calcium gradients, actin networks, and polarized secretion. The occurrence of these cellular events in stigmatic papillae coincides with the stages of pollen hydration and pollen tube entry into the stigmatic papillar cell wall. However, the form of the vesicle trafficking appears to differ between species, with vesicle-like structures detected in Arabidopsis species while exosomes were found to be secreted in Brassica species. Around the same timeframe, self-incompatible pollen recognition leads altered cellular responses in the stigmatic papillae to interfere with basal compatible pollen responses and disrupt regulated secretion, causing self-pollen rejection. Here, the literature on the changing cellular dynamics in the stigmatic papillae following pollination is reviewed and discussed in the context of other well-characterized examples of polarized secretion in plants.
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Affiliation(s)
- Daphne R Goring
- Department of Cell & Systems Biology, University of Toronto, Canada M5S 3B2
- Centre for the Analysis of Genome Evolution and Function, University of Toronto, Canada M5S 3B2
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46
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Slane D, Reichardt I, El Kasmi F, Bayer M, Jürgens G. Evolutionarily diverse SYP1 Qa-SNAREs jointly sustain pollen tube growth in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2017; 92:375-385. [PMID: 28792633 DOI: 10.1111/tpj.13659] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 08/01/2017] [Accepted: 08/03/2017] [Indexed: 05/08/2023]
Abstract
Intracellular membrane fusion is effected by SNARE proteins that reside on adjacent membranes and form bridging trans-SNARE complexes. Qa-SNARE members of the Arabidopsis SYP1 family are involved in membrane fusion at the plasma membrane or during cell plate formation. Three SYP1 family members have been classified as pollen-specific as inferred from gene expression profiling studies, and two of them, SYP124 and SYP125, are confined to angiosperms. The SYP124 gene appears genetically unstable, whereas its sister gene SYP125 shows essentially no variation among Arabidopsis accessions. The third pollen-specific member SYP131 is sister to SYP132, which appears evolutionarily conserved in the plant lineage. Although evolutionarily diverse, the three SYP1 proteins are functionally overlapping in that only the triple mutant syp124 syp125 syp131 shows a specific and severe male gametophytic defect. While pollen development and germination appear normal, pollen tube growth is arrested during passage through the style. Our results suggest that angiosperm pollen tubes employ a combination of ancient and modern Qa-SNARE proteins to sustain their growth-promoting membrane dynamics during the reproductive process.
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Affiliation(s)
- Daniel Slane
- Max Planck Institute for Developmental Biology, Cell Biology, 72076, Tübingen, Germany
| | - Ilka Reichardt
- ZMBP, Developmental Genetics, University of Tübingen, 72076, Tübingen, Germany
| | - Farid El Kasmi
- ZMBP, Developmental Genetics, University of Tübingen, 72076, Tübingen, Germany
| | - Martin Bayer
- Max Planck Institute for Developmental Biology, Cell Biology, 72076, Tübingen, Germany
| | - Gerd Jürgens
- Max Planck Institute for Developmental Biology, Cell Biology, 72076, Tübingen, Germany
- ZMBP, Developmental Genetics, University of Tübingen, 72076, Tübingen, Germany
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Aloisi I, Cai G, Faleri C, Navazio L, Serafini-Fracassini D, Del Duca S. Spermine Regulates Pollen Tube Growth by Modulating Ca 2+-Dependent Actin Organization and Cell Wall Structure. FRONTIERS IN PLANT SCIENCE 2017; 8:1701. [PMID: 29033970 PMCID: PMC5627395 DOI: 10.3389/fpls.2017.01701] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Accepted: 09/15/2017] [Indexed: 05/25/2023]
Abstract
Proper growth of the pollen tube depends on an elaborate mechanism that integrates several molecular and cytological sub-processes and ensures a cell shape adapted to the transport of gametes. This growth mechanism is controlled by several molecules among which cytoplasmic and apoplastic polyamines. Spermine (Spm) has been correlated with various physiological processes in pollen, including structuring of the cell wall and modulation of protein (mainly cytoskeletal) assembly. In this work, the effects of Spm on the growth of pear pollen tubes were analyzed. When exogenous Spm (100 μM) was supplied to germinating pollen, it temporarily blocked tube growth, followed by the induction of apical swelling. This reshaping of the pollen tube was maintained also after growth recovery, leading to a 30-40% increase of tube diameter. Apical swelling was also accompanied by a transient increase in cytosolic calcium concentration and alteration of pH values, which were the likely cause for major reorganization of actin filaments and cytoplasmic organelle movement. Morphological alterations of the apical and subapical region also involved changes in the deposition of pectin, cellulose, and callose in the cell wall. Thus, results point to the involvement of Spm in cell wall construction as well as cytoskeleton organization during pear pollen tube growth.
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Affiliation(s)
- Iris Aloisi
- Department of Biological, Geological and Environmental Sciences, University of Bologna, Bologna, Italy
| | - Giampiero Cai
- Department of Life Sciences, University of Siena, Siena, Italy
| | - Claudia Faleri
- Department of Life Sciences, University of Siena, Siena, Italy
| | | | | | - Stefano Del Duca
- Department of Biological, Geological and Environmental Sciences, University of Bologna, Bologna, Italy
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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: 3.1] [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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Peng X, Yan T, Sun M. The WASP-Arp2/3 complex signal cascade is involved in actin-dependent sperm nuclei migration during double fertilization in tobacco and maize. Sci Rep 2017; 7:43161. [PMID: 28225074 PMCID: PMC5320560 DOI: 10.1038/srep43161] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Accepted: 01/20/2017] [Indexed: 12/14/2022] Open
Abstract
Sperm nuclear migration during fertilization in Arabidopsis and rice has recently been found to be actin-dependent, but the driving force behind this actin cytoskeleton-dependent motion is unclear. Here, we confirmed that the actin-dependent sperm nuclei migration during fertilization is a conserved mechanism in plants. Using in vitro fertilization systems, we showed that a functional actin is also essential in maize and tobacco for sperm nuclei migration after gamete membrane fusion. Cytoskeleton depolymerization inhibitor treatments supported the view that sperm nuclei migration is actin-dependent but microtubule-independent in both egg cell and central cell during double fertilization. We further revealed that the actin-based motor myosin is not the driving force for sperm nuclear migration in maize and tobacco. The WASP-Arp2/3 complex signal cascade is shown here to be involved in the regulation of sperm nuclear migration in maize and tobacco. It is interesting that sperm nuclei migration within somatic cell also need WASP-Arp2/3 complex signal cascade and actin, suggesting that the mechanism of sperm nuclear migration is not gamete specific.
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Affiliation(s)
- Xiongbo Peng
- State Key Laboratory for Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Tingting Yan
- State Key Laboratory for Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Mengxiang Sun
- State Key Laboratory for Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
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50
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Zhang M, Zhang R, Qu X, Huang S. Arabidopsis FIM5 decorates apical actin filaments and regulates their organization in the pollen tube. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:3407-17. [PMID: 27117336 PMCID: PMC4892729 DOI: 10.1093/jxb/erw160] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The actin cytoskeleton is increasingly recognized as a major regulator of pollen tube growth. Actin filaments have distinct distribution patterns and dynamic properties within different regions of the pollen tube. Apical actin filaments are highly dynamic and crucial for pollen tube growth. However, how apical actin filaments are generated and properly constructed remains an open question. Here we showed that Arabidopsis fimbrin5 (FIM5) decorates filamentous structures throughout the entire tube but is apically concentrated. Apical actin structures are disorganized to different degrees in the pollen tubes of fim5 loss-of-function mutants. Further observations suggest that apical actin structures are not constructed properly because apical actin filaments cannot be maintained at the cortex of fim5 pollen tubes. Actin filaments appeared to be more curved in fim5 pollen tubes and this was confirmed by measurements showing that the convolutedness and the rate of change of convolutedness of actin filaments was significantly increased in fim5 pollen tubes. This suggests that the rigidity of the actin filaments may be compromised in fim5 pollen tubes. Further, the apical cell wall composition is altered, implying that tip-directed vesicle trafficking events are impaired in fim5 pollen tubes. Thus, we found that FIM5 decorates apical actin filaments and regulates their organization in order to drive polarized pollen tube growth.
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Affiliation(s)
- Meng Zhang
- Key Laboratory of Plant Molecular Physiology, Institute of Botany Chinese Academy of Sciences, Beijing 100093 China University of Chinese Academy of Sciences, Beijing 100049 China
| | - Ruihui Zhang
- Key Laboratory of Plant Molecular Physiology, Institute of Botany Chinese Academy of Sciences, Beijing 100093 China University of Chinese Academy of Sciences, Beijing 100049 China
| | - Xiaolu Qu
- Center for Plant Biology, School of Life Sciences, Tsinghua University Beijing 100084, China Tsinghua-Peking Joint Center for Life Sciences, Beijing 100084 China
| | - Shanjin Huang
- Key Laboratory of Plant Molecular Physiology, Institute of Botany Chinese Academy of Sciences, Beijing 100093 China Center for Plant Biology, School of Life Sciences, Tsinghua University Beijing 100084, China National Center for Plant Gene Research, Beijing 100101 China
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