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Zhang M, Tang C, Li Y, Lv S, Xie Z, Liu Z, Zhang H, Zhang S, Wang P, Wu J. The MYC transcription factor PbrMYC8 negatively regulates PbrMSL5 expression to promote pollen germination in Pyrus. Int J Biol Macromol 2024; 278:134640. [PMID: 39142484 DOI: 10.1016/j.ijbiomac.2024.134640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2024] [Revised: 07/22/2024] [Accepted: 08/08/2024] [Indexed: 08/16/2024]
Abstract
The successful germination of pollen is essential for double fertilization in flowering plants. Mechanosensitive channels of small conductance (MscS-like, MSL) inhibit pollen germination and maintains cellular integrity of pollen during this process. Therefore, it is vital to carefully regulate the expression of MSL to promote successful pollen germination. Despite its importance, the molecular mechanisms governing MSL expression in plants remain poorly understood. Here, we had identified 15 MSL genes in the pear, among which PbrMSL5 was expressed in pollen development. Subcellular localization experiments revealed that PbrMSL5 was located in both plasma membrane and cytoplasm. Functional investigations, including complementation experiments using the atmsl8 mutant background, demonstrated the involvement of PbrMSL5 in preserving pollen cell integrity and inhibiting germination. Antisense oligonucleotide experiments further confirmed that PbrMSL5 suppressed pear pollen germination by reducing osmotic pressure and Cl- content. Yeast one-hybrid, electrophoretic mobility shift assays, and dual luciferase reporter assay elucidated that PbrMYC8 interacts directly with the N-box element, leading to the suppression of PbrMSL5 expression and promoted pollen germination. These results represented a significant advancement in unraveling the molecular mechanisms controlling plant MSL expression. This study showed valuable contribution to advancing our comprehension of the mechanism underlying pollen germination.
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Affiliation(s)
- Mingliang Zhang
- Sanya Institute of Nanjing Agricultural University, State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Jiangsu Key Laboratory for Horticultural Crop Breeding, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | - Chao Tang
- Sanya Institute of Nanjing Agricultural University, State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Jiangsu Key Laboratory for Horticultural Crop Breeding, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | - Yu Li
- Sanya Institute of Nanjing Agricultural University, State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Jiangsu Key Laboratory for Horticultural Crop Breeding, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | - Shouzheng Lv
- Sanya Institute of Nanjing Agricultural University, State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Jiangsu Key Laboratory for Horticultural Crop Breeding, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | - Zhu Xie
- Sanya Institute of Nanjing Agricultural University, State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Jiangsu Key Laboratory for Horticultural Crop Breeding, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | - Zongqi Liu
- Sanya Institute of Nanjing Agricultural University, State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Jiangsu Key Laboratory for Horticultural Crop Breeding, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | - Hao Zhang
- Sanya Institute of Nanjing Agricultural University, State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Jiangsu Key Laboratory for Horticultural Crop Breeding, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | - Shaoling Zhang
- Sanya Institute of Nanjing Agricultural University, State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Jiangsu Key Laboratory for Horticultural Crop Breeding, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | - Peng Wang
- Sanya Institute of Nanjing Agricultural University, State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Jiangsu Key Laboratory for Horticultural Crop Breeding, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China.
| | - Juyou Wu
- Sanya Institute of Nanjing Agricultural University, State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Jiangsu Key Laboratory for Horticultural Crop Breeding, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China; Zhongshan Biological Breeding Laboratory, No.50 Zhongling Street, Nanjing, Jiangsu 210014, China.
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2
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Świeżawska-Boniecka B, Duszyn M, Kwiatkowski M, Szmidt-Jaworska A, Jaworski K. Cross Talk Between Cyclic Nucleotides and Calcium Signaling Pathways in Plants-Achievements and Prospects. FRONTIERS IN PLANT SCIENCE 2021; 12:643560. [PMID: 33664763 PMCID: PMC7921789 DOI: 10.3389/fpls.2021.643560] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 01/26/2021] [Indexed: 06/12/2023]
Abstract
A variety of plant cellular activities are regulated through mechanisms controlling the level of signal molecules, such as cyclic nucleotides (cNMPs, e.g., cyclic adenosine 3':5'-monophosphate, cAMP, and cyclic guanosine 3':5'- monophosphate, cGMP) and calcium ions (Ca2+). The mechanism regulating cNMP levels affects their synthesis, degradation, efflux and cellular distribution. Many transporters and the spatiotemporal pattern of calcium signals, which are transduced by multiple, tunable and often strategically positioned Ca2+-sensing elements, play roles in calcium homeostasis. Earlier studies have demonstrated that while cNMPs and Ca2+ can act separately in independent transduction pathways, they can interact and function together. Regardless of the context, the balance between Ca2+ and cNMP is the most important consideration. This balance seems to be crucial for effectors, such as phosphodiesterases, cyclic nucleotide gated channels and cyclase activity. Currently, a wide range of molecular biology techniques enable thorough analyses of cellular cross talk. In recent years, data have indicated relationships between calcium ions and cyclic nucleotides in mechanisms regulating specific signaling pathways. The purpose of this study is to summarize the current knowledge on nucleotide-calcium cross talk in plants.
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Blanco E, Fortunato S, Viggiano L, de Pinto MC. Cyclic AMP: A Polyhedral Signalling Molecule in Plants. Int J Mol Sci 2020; 21:E4862. [PMID: 32660128 PMCID: PMC7402341 DOI: 10.3390/ijms21144862] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Revised: 07/06/2020] [Accepted: 07/07/2020] [Indexed: 02/07/2023] Open
Abstract
The cyclic nucleotide cAMP (3',5'-cyclic adenosine monophosphate) is nowadays recognised as an important signalling molecule in plants, involved in many molecular processes, including sensing and response to biotic and abiotic environmental stresses. The validation of a functional cAMP-dependent signalling system in higher plants has spurred a great scientific interest on the polyhedral role of cAMP, as it actively participates in plant adaptation to external stimuli, in addition to the regulation of physiological processes. The complex architecture of cAMP-dependent pathways is far from being fully understood, because the actors of these pathways and their downstream target proteins remain largely unidentified. Recently, a genetic strategy was effectively used to lower cAMP cytosolic levels and hence shed light on the consequences of cAMP deficiency in plant cells. This review aims to provide an integrated overview of the current state of knowledge on cAMP's role in plant growth and response to environmental stress. Current knowledge of the molecular components and the mechanisms of cAMP signalling events is summarised.
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Affiliation(s)
- Emanuela Blanco
- Institute of Biosciences and Bioresources, National Research Council, Via G. Amendola 165/A, 70126 Bari, Italy
| | - Stefania Fortunato
- Department of Biology, University of Bari Aldo Moro, Via E. Orabona 4, 70125 Bari, Italy; (S.F.); (L.V.)
| | - Luigi Viggiano
- Department of Biology, University of Bari Aldo Moro, Via E. Orabona 4, 70125 Bari, Italy; (S.F.); (L.V.)
| | - Maria Concetta de Pinto
- Department of Biology, University of Bari Aldo Moro, Via E. Orabona 4, 70125 Bari, Italy; (S.F.); (L.V.)
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Lemtiri-Chlieh F, Arold ST, Gehring C. Mg 2+ Is a Missing Link in Plant Cell Ca 2+ Signalling and Homeostasis-A Study on Vicia faba Guard Cells. Int J Mol Sci 2020; 21:ijms21113771. [PMID: 32471040 PMCID: PMC7312177 DOI: 10.3390/ijms21113771] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Revised: 05/13/2020] [Accepted: 05/15/2020] [Indexed: 01/04/2023] Open
Abstract
Hyperpolarization-activated calcium channels (HACCs) are found in the plasma membrane and tonoplast of many plant cell types, where they have an important role in Ca2+-dependent signalling. The unusual gating properties of HACCs in plants, i.e., activation by membrane hyperpolarization rather than depolarization, dictates that HACCs are normally open in the physiological hyperpolarized resting membrane potential state (the so-called pump or P-state); thus, if not regulated, they would continuously leak Ca2+ into cells. HACCs are permeable to Ca2+, Ba2+, and Mg2+; activated by H2O2 and the plant hormone abscisic acid (ABA); and their activity in guard cells is greatly reduced by increasing amounts of free cytosolic Ca2+ ([Ca2+]Cyt), and hence closes during [Ca2+]Cyt surges. Here, we demonstrate that the presence of the commonly used Mg-ATP inside the guard cell greatly reduces HACC activity, especially at voltages ≤ −200 mV, and that Mg2+ causes this block. Therefore, we firstly conclude that physiological cytosolic Mg2+ levels affect HACC gating and that channel opening requires either high negative voltages (≥−200 mV) or displacement of Mg2+ away from the immediate vicinity of the channel. Secondly, based on structural comparisons with a Mg2+-sensitive animal inward-rectifying K+ channel, we propose that the likely candidate HACCs described here are cyclic nucleotide gated channels (CNGCs), many of which also contain a conserved diacidic Mg2+ binding motif within their pores. This conclusion is consistent with the electrophysiological data. Finally, we propose that Mg2+, much like in animal cells, is an important component in Ca2+ signalling and homeostasis in plants.
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Affiliation(s)
- Fouad Lemtiri-Chlieh
- King Abdullah University of Science and Technology (KAUST), Biological and Environmental Science and Engineering (BESE), Thuwal 23955-6900, Saudi Arabia;
- Department of Neuroscience, University of Connecticut School of Medicine, Farmington, CT 06030, USA
- Correspondence: (F.L.-C); (C.G.)
| | - Stefan T. Arold
- King Abdullah University of Science and Technology (KAUST), Biological and Environmental Science and Engineering (BESE), Thuwal 23955-6900, Saudi Arabia;
- King Abdullah University of Science and Technology (KAUST), Computational Bioscience Research Center (CBRC), Thuwal 23955-6900, Saudi Arabia
- Centre de Biochimie Structurale, CNRS, INSERM, Université de Montpellier, 34090 Montpellier, France
| | - Chris Gehring
- King Abdullah University of Science and Technology (KAUST), Biological and Environmental Science and Engineering (BESE), Thuwal 23955-6900, Saudi Arabia;
- Department of Chemistry, Biology & Biotechnology, University of Perugia, 06121 Perugia, Italy
- Correspondence: (F.L.-C); (C.G.)
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A Cyclic Nucleotide-Gated Channel, HvCNGC2-3, Is Activated by the Co-Presence of Na⁺ and K⁺ and Permeable to Na⁺ and K⁺ Non-Selectively. PLANTS 2018; 7:plants7030061. [PMID: 30049942 PMCID: PMC6161278 DOI: 10.3390/plants7030061] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 07/09/2018] [Accepted: 07/24/2018] [Indexed: 12/21/2022]
Abstract
Cyclic nucleotide-gated channels (CNGCs) have been postulated to contribute significantly in plant development and stress resistance. However, their electrophysiological properties remain poorly understood. Here, we characterized barley CNGC2-3 (HvCNGC2-3) by the two-electrode voltage-clamp technique in the Xenopus laevis oocyte heterologous expression system. Current was not observed in X. laevis oocytes injected with HvCNGC2-3 complementary RNA (cRNA) in a bathing solution containing either Na+ or K+ solely, even in the presence of 8-bromoadenosine 3′,5′-cyclic monophosphate (8Br-cAMP) or 8-bromoguanosine 3′,5′-cyclic monophosphate (8Br-cGMP). A weakly voltage-dependent slow hyperpolarization-activated ion current was observed in the co-presence of Na+ and K+ in the bathing solution and in the presence of 10 µM 8Br-cAMP, but not 8Br-cGMP. Permeability ratios of HvCNGC2-3 to K+, Na+ and Cl− were determined as 1:0.63:0.03 according to reversal-potential analyses. Amino-acid replacement of the unique ion-selective motif of HvCNGC2-3, AQGL, with the canonical motif, GQGL, resulted in the abolition of the current. This study reports a unique two-ion-dependent activation characteristic of the barley CNGC, HvCNGC2-3.
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Barberini ML, Sigaut L, Huang W, Mangano S, Juarez SPD, Marzol E, Estevez J, Obertello M, Pietrasanta L, Tang W, Muschietti J. Calcium dynamics in tomato pollen tubes using the Yellow Cameleon 3.6 sensor. PLANT REPRODUCTION 2018; 31:159-169. [PMID: 29236154 DOI: 10.1007/s00497-017-0317-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 12/04/2017] [Indexed: 06/07/2023]
Abstract
In vitro tomato pollen tubes show a cytoplasmic calcium gradient that oscillates with the same period as growth. Pollen tube growth requires coordination between the tip-focused cytoplasmic calcium concentration ([Ca2+]cyt) gradient and the actin cytoskeleton. This [Ca2+]cyt gradient is necessary for exocytosis of small vesicles, which contributes to the delivery of new membrane and cell wall at the pollen tube tip. The mechanisms that generate and maintain this [Ca2+]cyt gradient are not completely understood. Here, we studied calcium dynamics in tomato (Solanum lycopersicum) pollen tubes using transgenic tomato plants expressing the Yellow Cameleon 3.6 gene under the pollen-specific promoter LAT52. We use tomato as an experimental model because tomato is a Solanaceous plant that is easy to transform, and has an excellent genomic database and genetic stock center, and unlike Arabidopsis, tomato pollen is a good system to do biochemistry. We found that tomato pollen tubes showed an oscillating tip-focused [Ca2+]cyt gradient with the same period as growth. Then, we used a pharmacological approach to disturb the intracellular Ca2+ homeostasis, evaluating how the [Ca2+]cyt gradient, pollen germination and in vitro pollen tube growth were affected. We found that cyclopiazonic acid (CPA), a drug that inhibits plant PIIA-type Ca2+-ATPases, increased [Ca2+]cyt in the subapical zone, leading to the disappearance of the Ca2+ oscillations and inhibition of pollen tube growth. In contrast, 2-aminoethoxydiphenyl borate (2-APB), an inhibitor of Ca2+ released from the endoplasmic reticulum to the cytoplasm in animals cells, completely reduced [Ca2+]cyt at the tip of the tube, blocked the gradient and arrested pollen tube growth. Although both drugs have antagonistic effects on [Ca2+]cyt, both inhibited pollen tube growth triggering the disappearance of the [Ca2+]cyt gradient. When CPA and 2-APB were combined, their individual inhibitory effects on pollen tube growth were partially compensated. Finally, we found that GsMTx-4, a peptide from spider venom that blocks stretch-activated Ca2+ channels, inhibited tomato pollen germination and had a heterogeneous effect on pollen tube growth, suggesting that these channels are also involved in the maintenance of the [Ca2+]cyt gradient. All these results indicate that tomato pollen tube is an excellent model to study calcium dynamics.
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Affiliation(s)
- María Laura Barberini
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, "Dr. Héctor Torres" (INGEBI-CONICET), Vuelta de Obligado 2490, C1428ADN, Buenos Aires, Argentina
| | - Lorena Sigaut
- Instituto de Física de Buenos Aires (IFIBA-CONICET), Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldes 2160, Ciudad Universitaria, Pabellón I, C1428EHA, Buenos Aires, Argentina
| | - Weijie Huang
- National Key Laboratory of Plant Molecular Genetics, Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai, 200032, China
- Department of Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, United Kingdom
| | - Silvina Mangano
- Fundación Instituto Leloir and Instituto de Investigaciones Bioquímicas de Buenos Aires (IIBBA-CONICET), Av. Patricias Argentinas 435, CP C1405BWE, Buenos Aires, Argentina
| | - Silvina Paola Denita Juarez
- Fundación Instituto Leloir and Instituto de Investigaciones Bioquímicas de Buenos Aires (IIBBA-CONICET), Av. Patricias Argentinas 435, CP C1405BWE, Buenos Aires, Argentina
| | - Eliana Marzol
- Fundación Instituto Leloir and Instituto de Investigaciones Bioquímicas de Buenos Aires (IIBBA-CONICET), Av. Patricias Argentinas 435, CP C1405BWE, Buenos Aires, Argentina
| | - José Estevez
- Fundación Instituto Leloir and Instituto de Investigaciones Bioquímicas de Buenos Aires (IIBBA-CONICET), Av. Patricias Argentinas 435, CP C1405BWE, Buenos Aires, Argentina
| | - Mariana Obertello
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, "Dr. Héctor Torres" (INGEBI-CONICET), Vuelta de Obligado 2490, C1428ADN, Buenos Aires, Argentina
| | - Lía Pietrasanta
- Instituto de Física de Buenos Aires (IFIBA-CONICET), Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldes 2160, Ciudad Universitaria, Pabellón I, C1428EHA, Buenos Aires, Argentina
- Centro de Microscopías Avanzadas, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldes 2160, Ciudad Universitaria, Pabellón I, C1428EHA, Buenos Aires, Argentina
| | - Weihua Tang
- National Key Laboratory of Plant Molecular Genetics, Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai, 200032, China
| | - Jorge Muschietti
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, "Dr. Héctor Torres" (INGEBI-CONICET), Vuelta de Obligado 2490, C1428ADN, Buenos Aires, Argentina.
- Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldes 2160, Ciudad Universitaria, Pabellón II, C1428EGA, Buenos Aires, Argentina.
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Gehring C, Turek IS. Cyclic Nucleotide Monophosphates and Their Cyclases in Plant Signaling. FRONTIERS IN PLANT SCIENCE 2017; 8:1704. [PMID: 29046682 PMCID: PMC5632652 DOI: 10.3389/fpls.2017.01704] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 09/19/2017] [Indexed: 05/19/2023]
Abstract
The cyclic nucleotide monophosphates (cNMPs), and notably 3',5'-cyclic guanosine monophosphate (cGMP) and 3',5'-cyclic adenosine monophosphate (cAMP) are now accepted as key signaling molecules in many processes in plants including growth and differentiation, photosynthesis, and biotic and abiotic defense. At the single molecule level, we are now beginning to understand how cNMPs modify specific target molecules such as cyclic nucleotide-gated channels, while at the systems level, a recent study of the Arabidopsis cNMP interactome has identified novel target molecules with specific cNMP-binding domains. A major advance came with the discovery and characterization of a steadily increasing number of guanylate cyclases (GCs) and adenylate cyclases (ACs). Several of the GCs are receptor kinases and include the brassinosteroid receptor, the phytosulfokine receptor, the Pep receptor, the plant natriuretic peptide receptor as well as a nitric oxide sensor. We foresee that in the near future many more molecular mechanisms and biological roles of GCs and ACs and their catalytic products will be discovered and further establish cNMPs as a key component of plant responses to the environment.
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Affiliation(s)
- Chris Gehring
- Biological and Environmental Science and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Perugia, Italy
| | - Ilona S. Turek
- Biological and Environmental Science and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
- Leibniz Institute of Plant Biochemistry, Halle, Germany
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Cyclic nucleotide-gated channel 18 is an essential Ca2+ channel in pollen tube tips for pollen tube guidance to ovules in Arabidopsis. Proc Natl Acad Sci U S A 2016; 113:3096-101. [PMID: 26929345 DOI: 10.1073/pnas.1524629113] [Citation(s) in RCA: 116] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
In flowering plants, pollen tubes are guided into ovules by multiple attractants from female gametophytes to release paired sperm cells for double fertilization. It has been well-established that Ca(2+) gradients in the pollen tube tips are essential for pollen tube guidance and that plasma membrane Ca(2+) channels in pollen tube tips are core components that regulate Ca(2+) gradients by mediating and regulating external Ca(2+) influx. Therefore, Ca(2+) channels are the core components for pollen tube guidance. However, there is still no genetic evidence for the identification of the putative Ca(2+) channels essential for pollen tube guidance. Here, we report that the point mutations R491Q or R578K in cyclic nucleotide-gated channel 18 (CNGC18) resulted in abnormal Ca(2+) gradients and strong pollen tube guidance defects by impairing the activation of CNGC18 in Arabidopsis. The pollen tube guidance defects of cngc18-17 (R491Q) and of the transfer DNA (T-DNA) insertion mutant cngc18-1 (+/-) were completely rescued by CNGC18. Furthermore, domain-swapping experiments showed that CNGC18's transmembrane domains are indispensable for pollen tube guidance. Additionally, we found that, among eight Ca(2+) channels (including six CNGCs and two glutamate receptor-like channels), CNGC18 was the only one essential for pollen tube guidance. Thus, CNGC18 is the long-sought essential Ca(2+) channel for pollen tube guidance in Arabidopsis.
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9
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Qin Y, Shen X, Wang N, Ding X. Characterization of a novel cyclase-like gene family involved in controlling stress tolerance in rice. JOURNAL OF PLANT PHYSIOLOGY 2015; 181:30-41. [PMID: 25974367 DOI: 10.1016/j.jplph.2015.03.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 03/23/2015] [Accepted: 03/23/2015] [Indexed: 05/28/2023]
Abstract
A novel cyclase-like gene family (CYL) encodes proteins containing cyclase domain, but their functions are largely unknown. We report the systematic identification and characterization of CYL genes in the rice genome. Five putative CYL protein sequences (OsCYL1 to 4b) were identified. These sequences and other CYL homologs were classified into four subgroups based on phylogenetic analysis. Distinct diversification of these CYL proteins exists between plants and non-plants. The CYL family has conserved exon-intron structures, and the organizations of putative motifs in plants are specifically diverse. All OsCYL genes were expressed in a wide range of tissues or organs and were responsive to at least one of the abiotic stresses and hormone treatments applied. Protein OsCYL4a is targeted to the cell membrane. The overexpression of one stress-responsive gene OsCYL4a in rice resulted in decreased tolerance to salt, drought, cold, and oxidative stress. The expression levels of some abiotic stress-responsive factors, including H2O2-accumulating negative factors DST and OsSKIPa in OsCYL4a-overexpressing plants, were reduced compared with the wild type under normal condition and drought stress. These results suggest that rice CYL family may be functionally conserved polyketide cyclase, resulting in the rapid accumulation of reactive oxygen species to decrease tolerance to abiotic stresses.
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Affiliation(s)
- Yonghua Qin
- Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area, College of Life Sciences, South Central University for Nationalities, Wuhan 430074, China; National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan 430070, China
| | - Xin Shen
- Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area, College of Life Sciences, South Central University for Nationalities, Wuhan 430074, China
| | - Nili Wang
- National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan 430070, China
| | - Xipeng Ding
- Tropical Crops Genetic Resources Institute, Chinese Academy of Tropical Agricultural Sciences, Key Laboratory of Crop Gene Resources and Germplasm Enhancement in Southern China, Ministry of Agriculture, Danzhou 571737, Hainan, China; National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan 430070, China.
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10
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Hossain MA, Ye W, Munemasa S, Nakamura Y, Mori IC, Murata Y. Cyclic adenosine 5'-diphosphoribose (cADPR) cyclic guanosine 3',5'-monophosphate positively function in Ca(2+) elevation in methyl jasmonate-induced stomatal closure, cADPR is required for methyl jasmonate-induced ROS accumulation NO production in guard cells. PLANT BIOLOGY (STUTTGART, GERMANY) 2014; 16:1140-1144. [PMID: 24802616 DOI: 10.1111/plb.12175] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Accepted: 01/28/2014] [Indexed: 06/03/2023]
Abstract
Methyl jasmonate (MeJA) signalling shares several signal components with abscisic acid (ABA) signalling in guard cells. Cyclic adenosine 5'-diphosphoribose (cADPR) and cyclic guanosine 3',5'-monophosphate (cGMP) are second messengers in ABA-induced stomatal closure. In order to clarify involvement of cADPR and cGMP in MeJA-induced stomatal closure in Arabidopsis thaliana (Col-0), we investigated effects of an inhibitor of cADPR synthesis, nicotinamide (NA), and an inhibitor of cGMP synthesis, LY83583 (LY, 6-anilino-5,8-quinolinedione), on MeJA-induced stomatal closure. Treatment with NA and LY inhibited MeJA-induced stomatal closure. NA inhibited MeJA-induced reactive oxygen species (ROS) accumulation and nitric oxide (NO) production in guard cells. NA and LY suppressed transient elevations elicited by MeJA in cytosolic free Ca(2+) concentration ([Ca(2+)]cyt) in guard cells. These results suggest that cADPR and cGMP positively function in [Ca(2+)]cyt elevation in MeJA-induced stomatal closure, are signalling components shared with ABA-induced stomatal closure in Arabidopsis, and that cADPR is required for MeJA-induced ROS accumulation and NO production in Arabidopsis guard cells.
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Affiliation(s)
- M A Hossain
- Graduate School of Environmental and Life Science, Okayama University, Okayama, Japan
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11
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Wu J, Qin X, Tao S, Jiang X, Liang YK, Zhang S. Long-chain base phosphates modulate pollen tube growth via channel-mediated influx of calcium. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2014; 79:507-516. [PMID: 24905418 DOI: 10.1111/tpj.12576] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Revised: 05/22/2014] [Accepted: 05/28/2014] [Indexed: 06/03/2023]
Abstract
Long-chain base phosphates (LCBPs) have been correlated with amounts of crucial biological processes ranging from cell proliferation to apoptosis in animals. However, their functions in plants remain largely unknown. Here, we report that LCBPs, sphingosine-1-phosphate (S1P) and phytosphingosine-1-phosphate (Phyto-S1P), modulate pollen tube growth in a concentration-dependent bi-phasic manner. The pollen tube growth in the stylar transmitting tissue was promoted by SPHK1 overexpression (SPHK1-OE) but dampened by SPHK1 knockdown (SPHK1-KD) compared with wild-type of Arabidopsis; however, there was no detectable effect on in vitro pollen tube growth caused by misexpression of SPHK1. Interestingly, exogenous S1P or Phyto-S1P applications could increase the pollen tube growth rate in SPHK1-OE, SPHK1-KD and wild-type of Arabidopsis. Calcium ion (Ca(2+) )-imaging analysis showed that S1P triggered a remarkable increase in cytosolic Ca(2+) concentration in pollen. Extracellular S1P induced hyperpolarization-activated Ca(2+) currents in the pollen plasma membrane, and the Ca(2+) current activation was mediated by heterotrimeric G proteins. Moreover, the S1P-induced increase of cytosolic free Ca(2+) inhibited the influx of potassium ions in pollen tubes. Our findings suggest that LCBPs functions in a signaling cascade that facilitates Ca(2+) influx and modulates pollen tube growth.
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Affiliation(s)
- Juyou Wu
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing, 210095, China
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Jiang X, Gao Y, Zhou H, Chen J, Wu J, Zhang S. Apoplastic calmodulin promotes self-incompatibility pollen tube growth by enhancing calcium influx and reactive oxygen species concentration in Pyrus pyrifolia. PLANT CELL REPORTS 2014; 33:255-63. [PMID: 24145911 DOI: 10.1007/s00299-013-1526-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2013] [Revised: 10/03/2013] [Accepted: 10/09/2013] [Indexed: 05/17/2023]
Abstract
Calmodulin (CaM) has been associated with various physiological and developmental processes in plants, including pollen tube growth. In this study, we showed that CaM regulated the pear pollen tube growth in a concentration-dependent bi-phasic response. Using a whole-cell patch-clamp configuration, we showed that apoplastic CaM induced a hyperpolarization-activated calcium ion (Ca²⁺) current, and anti-CaM largely inhibited this type of Ca²⁺ current. Moreover, upon anti-CaM treatment, the reactive oxygen species (ROS) concentration decreased and actin filaments depolymerized in the pollen tube. Interestingly, CaM could partially rescue the inhibition of self-incompatible pear pollen tube growth. This phenotype could be mediated by CaM-enhanced pollen plasma membrane Ca²⁺ current, tip-localized ROS concentration and stabilized actin filaments. These data indicated that Ca²⁺, ROS and actin filaments were involved with CaM in regulating pollen tube growth and provide a potential way for overcoming pear self-incompatibility.
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Affiliation(s)
- Xueting Jiang
- College of Horticulture, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, No 6. Tongwei Road, Nanjing, 210095, China
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Tunc-Ozdemir M, Rato C, Brown E, Rogers S, Mooneyham A, Frietsch S, Myers CT, Poulsen LR, Malhó R, Harper JF. Cyclic nucleotide gated channels 7 and 8 are essential for male reproductive fertility. PLoS One 2013; 8:e55277. [PMID: 23424627 PMCID: PMC3570425 DOI: 10.1371/journal.pone.0055277] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2012] [Accepted: 12/29/2012] [Indexed: 01/03/2023] Open
Abstract
The Arabidopsis thaliana genome contains 20 CNGCs, which are proposed to encode cyclic nucleotide gated, non-selective, Ca²⁺-permeable ion channels. CNGC7 and CNGC8 are the two most similar with 74% protein sequence identity, and both genes are preferentially expressed in pollen. Two independent loss-of-function T-DNA insertions were identified for both genes and used to generate plant lines in which only one of the two alleles was segregating (e.g., cngc7-1+/-/cngc8-2-/- and cngc7-3-/-/cngc8-1+/-). While normal pollen transmission was observed for single gene mutations, pollen harboring mutations in both cngc7 and 8 were found to be male sterile (transmission efficiency reduced by more than 3000-fold). Pollen grains harboring T-DNA disruptions of both cngc7 and 8 displayed a high frequency of bursting when germinated in vitro. The male sterile defect could be rescued through pollen expression of a CNGC7 or 8 transgene including a CNGC7 with an N-terminal GFP-tag. However, rescue efficiencies were reduced ∼10-fold when the CNGC7 or 8 included an F to W substitution (F589W and F624W, respectively) at the junction between the putative cyclic nucleotide binding-site and the calmodulin binding-site, identifying this junction as important for proper functioning of a plant CNGC. Using confocal microscopy, GFP-CNGC7 was found to preferentially localize to the plasma membrane at the flanks of the growing tip. Together these results indicate that CNGC7 and 8 are at least partially redundant and provide an essential function at the initiation of pollen tube tip growth.
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Affiliation(s)
- Meral Tunc-Ozdemir
- Department of Biochemistry, University of Nevada, Reno, Nevada, United States of America
| | - Claudia Rato
- Universidade de Lisboa, Faculdade de Ciências de Lisboa, BioFIG, Lisboa, Portugal
| | - Elizabeth Brown
- Department of Biochemistry, University of Nevada, Reno, Nevada, United States of America
| | - Stephanie Rogers
- Department of Biochemistry, University of Nevada, Reno, Nevada, United States of America
| | - Amanda Mooneyham
- Department of Biochemistry, University of Nevada, Reno, Nevada, United States of America
| | - Sabine Frietsch
- Department of Biochemistry, University of Nevada, Reno, Nevada, United States of America
| | - Candace T. Myers
- Department of Biochemistry, University of Nevada, Reno, Nevada, United States of America
| | - Lisbeth Rosager Poulsen
- Department of Biochemistry, University of Nevada, Reno, Nevada, United States of America
- Department of Plant Biology and Biotechnology, Centre for Membrane Pumps in Cells and Disease (PUMPKIN), University of Copenhagen, Danish National Research Foundation, Frederiksberg, Denmark
| | - Rui Malhó
- Universidade de Lisboa, Faculdade de Ciências de Lisboa, BioFIG, Lisboa, Portugal
| | - Jeffrey F. Harper
- Department of Biochemistry, University of Nevada, Reno, Nevada, United States of America
- * E-mail:
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Tunc-Ozdemir M, Tang C, Ishka MR, Brown E, Groves NR, Myers CT, Rato C, Poulsen LR, McDowell S, Miller G, Mittler R, Harper JF. A cyclic nucleotide-gated channel (CNGC16) in pollen is critical for stress tolerance in pollen reproductive development. PLANT PHYSIOLOGY 2013; 161:1010-20. [PMID: 23370720 PMCID: PMC3560999 DOI: 10.1104/pp.112.206888] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Accepted: 12/10/2012] [Indexed: 05/18/2023]
Abstract
Cyclic nucleotide-gated channels (CNGCs) have been implicated in diverse aspects of plant growth and development, including responses to biotic and abiotic stress, as well as pollen tube growth and fertility. Here, genetic evidence identifies CNGC16 in Arabidopsis (Arabidopsis thaliana) as critical for pollen fertility under conditions of heat stress and drought. Two independent transfer DNA disruptions of cngc16 resulted in a greater than 10-fold stress-dependent reduction in pollen fitness and seed set. This phenotype was fully rescued through pollen expression of a CNGC16 transgene, indicating that cngc16-1 and 16-2 were both loss-of-function null alleles. The most stress-sensitive period for cngc16 pollen was during germination and the initiation of pollen tube tip growth. Pollen viability assays indicate that mutant pollen are also hypersensitive to external calcium chloride, a phenomenon analogous to calcium chloride hypersensitivities observed in other cngc mutants. A heat stress was found to increase concentrations of 3',5'-cyclic guanyl monophosphate in both pollen and leaves, as detected using an antibody-binding assay. A quantitative PCR analysis indicates that cngc16 mutant pollen have attenuated expression of several heat-stress response genes, including two heat shock transcription factor genes, HsfA2 and HsfB1. Together, these results provide evidence for a heat stress response pathway in pollen that connects a cyclic nucleotide signal, a Ca(2+)-permeable ion channel, and a signaling network that activates a downstream transcriptional heat shock response.
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Affiliation(s)
- Meral Tunc-Ozdemir
- Department of Biochemistry, University of Nevada, Reno, Nevada 89557 (M.T.-O., C.T., M.R.I., E.B., C.T.M., L.R.P., S.M., J.F.H.); Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210 (N.R.G.); Universidade de Lisboa, Faculdade de Ciências de Lisboa, BioFIG, 1749–016 Lisboa, Portugal (C.R.); Department of Plant Biology and Biotechnology, Centre for Membrane Pumps in Cells and Disease (PUMPKIN), University of Copenhagen, Danish National Research Foundation, 2000 Frederiksberg, Denmark (L.R.P.); and The Mina and Everard Goodman Faculty of Life Sciences Bar Ilan University, Ramat-Gan 52900, Israel (G.M.); and Department of Biological Sciences, University of North Texas, Denton, Texas 76203 (R.M.)
| | - Chong Tang
- Department of Biochemistry, University of Nevada, Reno, Nevada 89557 (M.T.-O., C.T., M.R.I., E.B., C.T.M., L.R.P., S.M., J.F.H.); Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210 (N.R.G.); Universidade de Lisboa, Faculdade de Ciências de Lisboa, BioFIG, 1749–016 Lisboa, Portugal (C.R.); Department of Plant Biology and Biotechnology, Centre for Membrane Pumps in Cells and Disease (PUMPKIN), University of Copenhagen, Danish National Research Foundation, 2000 Frederiksberg, Denmark (L.R.P.); and The Mina and Everard Goodman Faculty of Life Sciences Bar Ilan University, Ramat-Gan 52900, Israel (G.M.); and Department of Biological Sciences, University of North Texas, Denton, Texas 76203 (R.M.)
| | - Maryam Rahmati Ishka
- Department of Biochemistry, University of Nevada, Reno, Nevada 89557 (M.T.-O., C.T., M.R.I., E.B., C.T.M., L.R.P., S.M., J.F.H.); Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210 (N.R.G.); Universidade de Lisboa, Faculdade de Ciências de Lisboa, BioFIG, 1749–016 Lisboa, Portugal (C.R.); Department of Plant Biology and Biotechnology, Centre for Membrane Pumps in Cells and Disease (PUMPKIN), University of Copenhagen, Danish National Research Foundation, 2000 Frederiksberg, Denmark (L.R.P.); and The Mina and Everard Goodman Faculty of Life Sciences Bar Ilan University, Ramat-Gan 52900, Israel (G.M.); and Department of Biological Sciences, University of North Texas, Denton, Texas 76203 (R.M.)
| | - Elizabeth Brown
- Department of Biochemistry, University of Nevada, Reno, Nevada 89557 (M.T.-O., C.T., M.R.I., E.B., C.T.M., L.R.P., S.M., J.F.H.); Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210 (N.R.G.); Universidade de Lisboa, Faculdade de Ciências de Lisboa, BioFIG, 1749–016 Lisboa, Portugal (C.R.); Department of Plant Biology and Biotechnology, Centre for Membrane Pumps in Cells and Disease (PUMPKIN), University of Copenhagen, Danish National Research Foundation, 2000 Frederiksberg, Denmark (L.R.P.); and The Mina and Everard Goodman Faculty of Life Sciences Bar Ilan University, Ramat-Gan 52900, Israel (G.M.); and Department of Biological Sciences, University of North Texas, Denton, Texas 76203 (R.M.)
| | - Norman R. Groves
- Department of Biochemistry, University of Nevada, Reno, Nevada 89557 (M.T.-O., C.T., M.R.I., E.B., C.T.M., L.R.P., S.M., J.F.H.); Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210 (N.R.G.); Universidade de Lisboa, Faculdade de Ciências de Lisboa, BioFIG, 1749–016 Lisboa, Portugal (C.R.); Department of Plant Biology and Biotechnology, Centre for Membrane Pumps in Cells and Disease (PUMPKIN), University of Copenhagen, Danish National Research Foundation, 2000 Frederiksberg, Denmark (L.R.P.); and The Mina and Everard Goodman Faculty of Life Sciences Bar Ilan University, Ramat-Gan 52900, Israel (G.M.); and Department of Biological Sciences, University of North Texas, Denton, Texas 76203 (R.M.)
| | | | | | - Lisbeth R. Poulsen
- Department of Biochemistry, University of Nevada, Reno, Nevada 89557 (M.T.-O., C.T., M.R.I., E.B., C.T.M., L.R.P., S.M., J.F.H.); Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210 (N.R.G.); Universidade de Lisboa, Faculdade de Ciências de Lisboa, BioFIG, 1749–016 Lisboa, Portugal (C.R.); Department of Plant Biology and Biotechnology, Centre for Membrane Pumps in Cells and Disease (PUMPKIN), University of Copenhagen, Danish National Research Foundation, 2000 Frederiksberg, Denmark (L.R.P.); and The Mina and Everard Goodman Faculty of Life Sciences Bar Ilan University, Ramat-Gan 52900, Israel (G.M.); and Department of Biological Sciences, University of North Texas, Denton, Texas 76203 (R.M.)
| | - Stephen McDowell
- Department of Biochemistry, University of Nevada, Reno, Nevada 89557 (M.T.-O., C.T., M.R.I., E.B., C.T.M., L.R.P., S.M., J.F.H.); Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210 (N.R.G.); Universidade de Lisboa, Faculdade de Ciências de Lisboa, BioFIG, 1749–016 Lisboa, Portugal (C.R.); Department of Plant Biology and Biotechnology, Centre for Membrane Pumps in Cells and Disease (PUMPKIN), University of Copenhagen, Danish National Research Foundation, 2000 Frederiksberg, Denmark (L.R.P.); and The Mina and Everard Goodman Faculty of Life Sciences Bar Ilan University, Ramat-Gan 52900, Israel (G.M.); and Department of Biological Sciences, University of North Texas, Denton, Texas 76203 (R.M.)
| | - Gad Miller
- Department of Biochemistry, University of Nevada, Reno, Nevada 89557 (M.T.-O., C.T., M.R.I., E.B., C.T.M., L.R.P., S.M., J.F.H.); Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210 (N.R.G.); Universidade de Lisboa, Faculdade de Ciências de Lisboa, BioFIG, 1749–016 Lisboa, Portugal (C.R.); Department of Plant Biology and Biotechnology, Centre for Membrane Pumps in Cells and Disease (PUMPKIN), University of Copenhagen, Danish National Research Foundation, 2000 Frederiksberg, Denmark (L.R.P.); and The Mina and Everard Goodman Faculty of Life Sciences Bar Ilan University, Ramat-Gan 52900, Israel (G.M.); and Department of Biological Sciences, University of North Texas, Denton, Texas 76203 (R.M.)
| | - Ron Mittler
- Department of Biochemistry, University of Nevada, Reno, Nevada 89557 (M.T.-O., C.T., M.R.I., E.B., C.T.M., L.R.P., S.M., J.F.H.); Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210 (N.R.G.); Universidade de Lisboa, Faculdade de Ciências de Lisboa, BioFIG, 1749–016 Lisboa, Portugal (C.R.); Department of Plant Biology and Biotechnology, Centre for Membrane Pumps in Cells and Disease (PUMPKIN), University of Copenhagen, Danish National Research Foundation, 2000 Frederiksberg, Denmark (L.R.P.); and The Mina and Everard Goodman Faculty of Life Sciences Bar Ilan University, Ramat-Gan 52900, Israel (G.M.); and Department of Biological Sciences, University of North Texas, Denton, Texas 76203 (R.M.)
| | - Jeffrey F. Harper
- Department of Biochemistry, University of Nevada, Reno, Nevada 89557 (M.T.-O., C.T., M.R.I., E.B., C.T.M., L.R.P., S.M., J.F.H.); Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210 (N.R.G.); Universidade de Lisboa, Faculdade de Ciências de Lisboa, BioFIG, 1749–016 Lisboa, Portugal (C.R.); Department of Plant Biology and Biotechnology, Centre for Membrane Pumps in Cells and Disease (PUMPKIN), University of Copenhagen, Danish National Research Foundation, 2000 Frederiksberg, Denmark (L.R.P.); and The Mina and Everard Goodman Faculty of Life Sciences Bar Ilan University, Ramat-Gan 52900, Israel (G.M.); and Department of Biological Sciences, University of North Texas, Denton, Texas 76203 (R.M.)
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Steinhorst L, Kudla J. Calcium - a central regulator of pollen germination and tube growth. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1833:1573-81. [PMID: 23072967 DOI: 10.1016/j.bbamcr.2012.10.009] [Citation(s) in RCA: 193] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Revised: 10/01/2012] [Accepted: 10/06/2012] [Indexed: 12/30/2022]
Abstract
Pollen tubes grow rapidly by very fast rates and reach extended lengths to bring about fertilization during plant reproduction. The pollen tube grows exclusively at its tip. Fundamental for such local, tip-focused growth are the presence of internal gradients and transmembrane fluxes of ions. Consequently, vegetative pollen tube cells are an excellent single cell model system to investigate cell biological processes of vesicle transport, cytoskeleton reorganization and regulation of ion transport. The second messenger Ca(2+) has emerged as a central and crucial modulator that not only regulates but also integrates the coordination each of these processes. In this review we reflect on recent advances in our understanding of the mechanisms of Ca(2+) function in pollen tube growth, focusing on its role in basic cellular processes such as control of cell growth, vesicular transport and intracellular signaling by localized gradients of second messengers. In particular we discuss new insights into the identity and role of Ca(2+) conductive ion channels and present experimental addressable hypotheses about their regulation. This article is part of a Special Issue entitled:12th European Symposium on Calcium.
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Affiliation(s)
- Leonie Steinhorst
- Institut für Biologie und Biotechnologie der Pflanzen, Universität Münster, Münster, Germany
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Hepler PK, Kunkel JG, Rounds CM, Winship LJ. Calcium entry into pollen tubes. TRENDS IN PLANT SCIENCE 2012; 17:32-8. [PMID: 22104406 DOI: 10.1016/j.tplants.2011.10.007] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Revised: 10/20/2011] [Accepted: 10/25/2011] [Indexed: 05/22/2023]
Abstract
Growing pollen tubes require calcium to maintain a tip-focused cytosolic gradient and as a constituent of the constantly expanding cell wall. Advances in cell and molecular biology as well as electrophysiology implicate several candidate channels and receptors in the flow of calcium into the cell. In this review we discuss the channels that have been identified and consider the role of the growing tip cell wall acting as a sink for calcium thus accounting for differences in oscillatory phase between influx measured on the outside of the cell and changes in tip concentration inside the cell. We also briefly draw attention to uptake mechanisms that restrict and shape the calcium signature in the growing pollen tube.
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Affiliation(s)
- Peter K Hepler
- Biology Department, University of Massachusetts, Amherst, MA 01003, USA.
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Rounds CM, Winship LJ, Hepler PK. Pollen tube energetics: respiration, fermentation and the race to the ovule. AOB PLANTS 2011; 2011:plr019. [PMID: 22476489 PMCID: PMC3169925 DOI: 10.1093/aobpla/plr019] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2011] [Accepted: 06/16/2011] [Indexed: 05/20/2023]
Abstract
BACKGROUND Pollen tubes grow by transferring chemical energy from stored cellular starch and newly assimilated sugars into ATP. This drives myriad processes essential for cell elongation, directly or through the creation of ion gradients. Respiration plays a central role in generating and regulating this energy flow and thus in the success of plant reproduction. Pollen tubes are easily grown in vitro and have become an excellent model for investigating the contributions of respiration to plant cellular growth and morphogenesis at the molecular, biochemical and physiological levels. SCOPE In recent decades, pollen tube research has become increasingly focused on the molecular mechanisms involved in cellular processes. Yet, effective growth and development requires an intact, integrated set of cellular processes, all supplied with a constant flow of energy. Here we bring together information from the current and historical literature concerning respiration, fermentation and mitochondrial physiology in pollen tubes, and assess the significance of more recent molecular and genetic investigations in a physiological context. CONCLUSIONS The rapid growth of the pollen tube down the style has led to the evolution of high rates of pollen tube respiration. Respiration rates in lily predict a total energy turnover of 40-50 fmol ATP s(-1) per pollen grain. Within this context we examine the energetic requirements of cell wall synthesis, osmoregulation, actin dynamics and cyclosis. At present, we can only estimate the amount of energy required, because data from growing pollen tubes are not available. In addition to respiration, we discuss fermentation and mitochondrial localization. We argue that the molecular pathways need to be examined within the physiological context to understand better the mechanisms that control tip growth in pollen tubes.
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Affiliation(s)
- Caleb M. Rounds
- Department of Biology, University of Massachusetts, Amherst, MA 01003, USA
| | | | - Peter K. Hepler
- Department of Biology, University of Massachusetts, Amherst, MA 01003, USA
- Corresponding author's e-mail address:
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