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Clark G, Tripathy MK, Roux SJ. Growth regulation by apyrases: Insights from altering their expression level in different organisms. Plant Physiol 2024; 194:1323-1335. [PMID: 37947023 PMCID: PMC10904326 DOI: 10.1093/plphys/kiad590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 09/28/2023] [Accepted: 09/28/2023] [Indexed: 11/12/2023]
Abstract
Apyrase (APY) enzymes are nucleoside triphosphate (NTP) diphosphohydrolases that can remove the terminal phosphate from NTPs and nucleoside diphosphates but not from nucleoside monophosphates. They have conserved structures and functions in yeast, plants, and animals. Among the most studied APYs in plants are those in Arabidopsis (Arabidopsis thaliana; AtAPYs) and pea (Pisum sativum; PsAPYs), both of which have been shown to play major roles in regulating plant growth and development. Valuable insights on their functional roles have been gained by transgenically altering their transcript abundance, either by constitutively expressing or suppressing APY genes. This review focuses on recent studies that have provided insights on the mechanisms by which APY activity promotes growth in different organisms. Most of these studies have used transgenic lines that constitutively expressed APY in multiple different plants and in yeast. As APY enzymatic activity can also be changed post-translationally by chemical blockage, this review also briefly covers studies that used inhibitors to suppress APY activity in plants and fungi. It concludes by summarizing some of the main unanswered questions about how APYs regulate plant growth and proposes approaches to answering them.
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Affiliation(s)
- Greg Clark
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, 100 E 24th Street, TX 78712, USA
| | | | - Stanley J Roux
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, 100 E 24th Street, TX 78712, USA
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2
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Tripathy MK, Roux SJ. Role of calcium in regulating key steps in phytochrome-induced signaling pathways. Physiol Mol Biol Plants 2023; 29:1875-1879. [PMID: 38222279 PMCID: PMC10784251 DOI: 10.1007/s12298-023-01403-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 11/09/2023] [Accepted: 12/08/2023] [Indexed: 01/16/2024]
Abstract
A major focus in the field of signal transduction pathways in plants has been the role of calcium ions in mediating diverse sensory responses. Among these responses, those initiated by the red-light activated photoreceptor, phytochrome have received increasing attention in recent years. Although not all phytochrome responses are mediated by calcium, many of them are, and a number of recent publications have clarified just how calcium helps to transduce some of the transcriptomic changes induced by phytochrome. Many of these publications reference Dr. Sopory's laboratory as an important contributor to the initial data documenting that an early step in the signaling pathways induced by phytochrome was an increased uptake of calcium into cells. This review summarizes the strong evidence that calcium-dependent steps play a major role in transducing phytochrome-initiated responses, and it updates the latest reports on specific steps in some phytochrome responses that are dependent on the mediation of calcium-binding protein kinases and calmodulin.
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Affiliation(s)
- Manas K. Tripathy
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712 USA
| | - Stanley J. Roux
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712 USA
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3
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Cannon AE, Vanegas DC, Sabharwal T, Salmi ML, Wang J, Clark G, McLamore ES, Roux SJ. Polarized distribution of extracellular nucleotides promotes gravity-directed polarization of development in spores of Ceratopteris richardii. Front Plant Sci 2023; 14:1265458. [PMID: 37854113 PMCID: PMC10579945 DOI: 10.3389/fpls.2023.1265458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Accepted: 09/18/2023] [Indexed: 10/20/2023]
Abstract
Gravity directs the polarization of Ceratopteris fern spores. This process begins with the uptake of calcium through channels at the bottom of the spore, a step necessary for the gravity response. Data showing that extracellular ATP (eATP) regulates calcium channels led to the hypothesis that extracellular nucleotides could play a role in the gravity-directed polarization of Ceratopteris spores. In animal and plant cells ATP can be released from mechanosensitive channels. This report tests the hypothesis that the polarized release of ATP from spores could be activated by gravity, preferentially along the bottom of the spore, leading to an asymmetrical accumulation of eATP. In order to carry out this test, an ATP biosensor was used to measure the [eATP] at the bottom and top of germinating spores during gravity-directed polarization. The [eATP] along the bottom of the spore averaged 7-fold higher than the concentration at the top. All treatments that disrupted eATP signaling resulted in a statistically significant decrease in the gravity response. In order to investigate the source of ATP release, spores were treated with Brefeldin A (BFA) and gadolinium trichloride (GdCl3). These treatments resulted in a significant decrease in gravity-directed polarization. An ATP biosensor was also used to measure ATP release after treatment with both BFA and GdCl3. Both of these treatments caused a significant decrease in [ATP] measured around spores. These results support the hypothesis that ATP could be released from mechanosensitive channels and secretory vesicles during the gravity-directed polarization of Ceratopteris spores.
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Affiliation(s)
- Ashley E. Cannon
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, United States
| | - Diana C. Vanegas
- Agricultural and Biological Engineering Department, The University of Florida, Gainesville, FL, United States
| | - Tanya Sabharwal
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, United States
| | - Mari L. Salmi
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, United States
| | - Jeffrey Wang
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, United States
| | - Greg Clark
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, United States
| | - Eric S. McLamore
- Agricultural and Biological Engineering Department, The University of Florida, Gainesville, FL, United States
| | - Stanley J. Roux
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, United States
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4
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Cannon AE, Sabharwal T, Salmi ML, Chittari GK, Annamalai V, Leggett L, Morris H, Slife C, Clark G, Roux SJ. Two distinct light-induced reactions are needed to promote germination in spores of Ceratopteris richardii. Front Plant Sci 2023; 14:1150199. [PMID: 37332704 PMCID: PMC10272463 DOI: 10.3389/fpls.2023.1150199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 05/18/2023] [Indexed: 06/20/2023]
Abstract
Germination of Ceratopteris richardii spores is initiated by light and terminates 3-4 days later with the emergence of a rhizoid. Early studies documented that the photoreceptor for initiating this response is phytochrome. However, completion of germination requires additional light input. If no further light stimulus is given after phytochrome photoactivation, the spores do not germinate. Here we show that a crucial second light reaction is required, and its function is to activate and sustain photosynthesis. Even in the presence of light, blocking photosynthesis with DCMU after phytochrome photoactivation blocks germination. In addition, RT-PCR showed that transcripts for different phytochromes are expressed in spores in darkness, and the photoactivation of these phytochromes results in the increased transcription of messages encoding chlorophyll a/b binding proteins. The lack of chlorophyll-binding protein transcripts in unirradiated spores and their slow accumulation makes it unlikely that photosynthesis is required for the initial light reaction. This conclusion is supported by the observation that the transient presence of DCMU, only during the initial light reaction, had no effect on germination. Additionally, the [ATP] in Ceratopteris richardii spores increased coincidentally with the length of light treatment during germination. Overall, these results support the conclusion that two distinct light reactions are required for the germination of Ceratopteris richardii spores.
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Sabharwal T, Lu Z, Slocum RD, Kang S, Wang H, Jiang HW, Veerappa R, Romanovicz D, Nam JC, Birk S, Clark G, Roux SJ. Constitutive expression of a pea apyrase, psNTP9, increases seed yield in field-grown soybean. Sci Rep 2022; 12:10870. [PMID: 35760854 PMCID: PMC9237067 DOI: 10.1038/s41598-022-14821-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 06/13/2022] [Indexed: 12/02/2022] Open
Abstract
To address the demand for food by a rapidly growing human population, agricultural scientists have carried out both plant breeding and genetic engineering research. Previously, we reported that the constitutive expression of a pea apyrase (Nucleoside triphosphate, diphosphohydrolase) gene, psNTP9, under the control of the CaMV35S promoter, resulted in soybean plants with an expanded root system architecture, enhanced drought resistance and increased seed yield when they are grown in greenhouses under controlled conditions. Here, we report that psNTP9-expressing soybean lines also show significantly enhanced seed yields when grown in multiple different field conditions at multiple field sites, including when the gene is introgressed into elite germplasm. The transgenic lines have higher leaf chlorophyll and soluble protein contents and decreased stomatal density and cuticle permeability, traits that increase water use efficiency and likely contribute to the increased seed yields of field-grown plants. These altered properties are explained, in part, by genome-wide gene expression changes induced by the transgene.
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Affiliation(s)
- Tanya Sabharwal
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, 78712, USA
| | | | - Robert D Slocum
- Program in Biological Sciences, Goucher College, Towson, MD, 21204, USA
| | - Seongjoon Kang
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Huan Wang
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Han-Wei Jiang
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Roopadarshini Veerappa
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Dwight Romanovicz
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Ji Chul Nam
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Simon Birk
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Greg Clark
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Stanley J Roux
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, 78712, USA.
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6
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Weeraratne G, Wang H, Weeraratne TP, Sabharwal T, Jiang HW, Cantero A, Clark G, Roux SJ. APYRASE1/2 mediate red light-induced de-etiolation growth in Arabidopsis seedlings. Plant Physiol 2022; 189:1728-1740. [PMID: 35357495 PMCID: PMC9237676 DOI: 10.1093/plphys/kiac150] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 03/07/2022] [Indexed: 05/09/2023]
Abstract
In etiolated seedlings, red light (R) activates phytochrome and initiates signals that generate major changes at molecular and physiological levels. These changes include inhibition of hypocotyl growth and promotion of the growth of primary roots, apical hooks, and cotyledons. An earlier report showed that the sharp decrease in hypocotyl growth rapidly induced by R was accompanied by an equally rapid decrease in the transcript and protein levels of two closely related apyrases (APYs; nucleoside triphosphate-diphosphohydrolases) in Arabidopsis (Arabidopsis thaliana), APY1 and APY2, enzymes whose expression alters auxin transport and growth in seedlings. Here, we report that single knockouts of either APY inhibit R-induced promotion of the growth of primary roots, apical hooks, and cotyledons, and RNAi-induced suppression of APY1 expression in the background of apy2 inhibits R-induced apical hook opening. When R-irradiated primary roots and apical hook-cotyledons began to show a gradual increase in their growth relative to dark controls, they concurrently showed increased levels of APY protein, but in hook-cotyledon tissue, this occurred without parallel increases in their transcripts. In wild-type seedlings whose root growth is suppressed by the photosynthesis inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea, the R-induced increased APY expression in roots was also inhibited. In unirradiated plants, the constitutive expression of APY2 promoted both hook opening and changes in the transcript abundance of Small Auxin Upregulated RNA (SAUR), SAUR17 and SAUR50 that help mediate de-etiolation. These results provide evidence that the expression of APY1/APY2 is regulated by R and that APY1/APY2 participate in the signaling pathway by which phytochrome induces differential growth changes in different tissues of etiolated seedlings.
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Affiliation(s)
- Gayani Weeraratne
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Huan Wang
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Tharindu P Weeraratne
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Tanya Sabharwal
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Han-Wei Jiang
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Araceli Cantero
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Greg Clark
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712, USA
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7
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Clark G, Brown KA, Tripathy MK, Roux SJ. Recent Advances Clarifying the Structure and Function of Plant Apyrases (Nucleoside Triphosphate Diphosphohydrolases). Int J Mol Sci 2021; 22:ijms22063283. [PMID: 33807069 PMCID: PMC8004787 DOI: 10.3390/ijms22063283] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 03/18/2021] [Accepted: 03/20/2021] [Indexed: 01/22/2023] Open
Abstract
Studies implicating an important role for apyrase (NTPDase) enzymes in plant growth and development began appearing in the literature more than three decades ago. After early studies primarily in potato, Arabidopsis and legumes, especially important discoveries that advanced an understanding of the biochemistry, structure and function of these enzymes have been published in the last half-dozen years, revealing that they carry out key functions in diverse other plants. These recent discoveries about plant apyrases include, among others, novel findings on its crystal structures, its biochemistry, its roles in plant stress responses and its induction of major changes in gene expression when its expression is suppressed or enhanced. This review will describe and discuss these recent advances and the major questions about plant apyrases that remain unanswered.
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Affiliation(s)
- Greg Clark
- Department of Molecular Biosciences, University of Texas, Austin, TX 78712, USA; (G.C.); (K.A.B.)
| | - Katherine A. Brown
- Department of Molecular Biosciences, University of Texas, Austin, TX 78712, USA; (G.C.); (K.A.B.)
- Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE, UK
| | | | - Stanley J. Roux
- Department of Molecular Biosciences, University of Texas, Austin, TX 78712, USA; (G.C.); (K.A.B.)
- Correspondence: ; Tel.: +1-512-471-4238
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8
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McWhite CD, Papoulas O, Drew K, Cox RM, June V, Dong OX, Kwon T, Wan C, Salmi ML, Roux SJ, Browning KS, Chen ZJ, Ronald PC, Marcotte EM. A Pan-plant Protein Complex Map Reveals Deep Conservation and Novel Assemblies. Cell 2020; 181:460-474.e14. [PMID: 32191846 DOI: 10.1016/j.cell.2020.02.049] [Citation(s) in RCA: 97] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 01/08/2020] [Accepted: 02/21/2020] [Indexed: 01/11/2023]
Abstract
Plants are foundational for global ecological and economic systems, but most plant proteins remain uncharacterized. Protein interaction networks often suggest protein functions and open new avenues to characterize genes and proteins. We therefore systematically determined protein complexes from 13 plant species of scientific and agricultural importance, greatly expanding the known repertoire of stable protein complexes in plants. By using co-fractionation mass spectrometry, we recovered known complexes, confirmed complexes predicted to occur in plants, and identified previously unknown interactions conserved over 1.1 billion years of green plant evolution. Several novel complexes are involved in vernalization and pathogen defense, traits critical for agriculture. We also observed plant analogs of animal complexes with distinct molecular assemblies, including a megadalton-scale tRNA multi-synthetase complex. The resulting map offers a cross-species view of conserved, stable protein assemblies shared across plant cells and provides a mechanistic, biochemical framework for interpreting plant genetics and mutant phenotypes.
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Affiliation(s)
- Claire D McWhite
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, University of Texas, Austin, TX 78712, USA
| | - Ophelia Papoulas
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, University of Texas, Austin, TX 78712, USA
| | - Kevin Drew
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, University of Texas, Austin, TX 78712, USA
| | - Rachael M Cox
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, University of Texas, Austin, TX 78712, USA
| | - Viviana June
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, University of Texas, Austin, TX 78712, USA
| | - Oliver Xiaoou Dong
- Department of Plant Pathology and The Genome Center, University of California, Davis, Davis, CA 95616, USA; Joint Bioenergy Institute, Emeryville, CA 94608, USA
| | - Taejoon Kwon
- Department of Biomedical Engineering, School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulju-gun, Ulsan 44919, Republic of Korea
| | - Cuihong Wan
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, University of Texas, Austin, TX 78712, USA; Hubei Key Lab of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, No. 152 Luoyu Road, Wuhan 430079, P.R. China
| | - Mari L Salmi
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, University of Texas, Austin, TX 78712, USA
| | - Stanley J Roux
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, University of Texas, Austin, TX 78712, USA
| | - Karen S Browning
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, University of Texas, Austin, TX 78712, USA
| | - Z Jeffrey Chen
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, University of Texas, Austin, TX 78712, USA
| | - Pamela C Ronald
- Department of Plant Pathology and The Genome Center, University of California, Davis, Davis, CA 95616, USA; Joint Bioenergy Institute, Emeryville, CA 94608, USA
| | - Edward M Marcotte
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, University of Texas, Austin, TX 78712, USA.
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9
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Veerappa R, Slocum RD, Siegenthaler A, Wang J, Clark G, Roux SJ. Ectopic expression of a pea apyrase enhances root system architecture and drought survival in Arabidopsis and soybean. Plant Cell Environ 2019; 42:337-353. [PMID: 30132918 DOI: 10.1111/pce.13425] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 08/13/2018] [Indexed: 05/27/2023]
Abstract
Ectoapyrases (ecto-NTPDases) function to decrease levels of extracellular ATP and ADP in animals and plants. Prior studies showed that ectopic expression of a pea ectoapyrase, psNTP9, enhanced growth in Arabidopsis seedlings and that the overexpression of the two Arabidopsis apyrases most closely related to psNTP9 enhanced auxin transport and growth in Arabidopsis. These results predicted that ectopic expression of psNTP9 could promote a more extensive root system architecture (RSA) in Arabidopsis. We confirmed that transgenic Arabidopsis seedlings had longer primary roots, more lateral roots, and more and longer root hairs than wild-type plants. Because RSA influences water uptake, we tested whether the transgenic plants could tolerate osmotic stress and water deprivation better than wild-type plants, and we confirmed these properties. Transcriptomic analyses revealed gene expression changes in the transgenic plants that helped account for their enhanced RSA and improved drought tolerance. The effects of psNTP9 were not restricted to Arabidopsis, because its expression in soybeans improved the RSA, growth, and seed yield of this crop and supported higher survival in response to drought. Our results indicate that in both Arabidopsis and soybeans, the constitutive expression of psNTP9 results in a more extensive RSA and improved survival in drought stress conditions.
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Affiliation(s)
| | - Robert D Slocum
- Department of Biological Sciences, Goucher College, Towson, Maryland
| | | | - Jing Wang
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas
| | - Greg Clark
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas
| | - Stanley J Roux
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas
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10
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Abstract
Among the most recently discovered chemical regulators of plant growth and development are extracellular nucleotides, especially extracellular ATP (eATP) and extracellular ADP (eADP). Plant cells release ATP into their extracellular matrix under a variety of different circumstances, and this eATP can then function as an agonist that binds to a specific receptor and induces signaling changes, the earliest of which is an increase in the concentration of cytosolic calcium ([Ca2+]cyt). This initial change is then amplified into downstream-signaling changes that include increased levels of reactive oxygen species and nitric oxide, which ultimately lead to major changes in the growth rate, defense responses, and leaf stomatal apertures of plants. This review presents and discusses the evidence that links receptor activation to increased [Ca2+]cyt and, ultimately, to growth and diverse adaptive changes in plant development. It also discusses the evidence that increased [Ca2+]cyt also enhances the activity of apyrase (nucleoside triphosphate diphosphohydrolase) enzymes that function in multiple subcellular locales to hydrolyze ATP and ADP, and thus limit or terminate the effects of these potent regulators.
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Affiliation(s)
- Greg Clark
- Department of Molecular Biosciences, University of Texas, Austin, TX 78712, USA.
| | - Stanley J Roux
- Department of Molecular Biosciences, University of Texas, Austin, TX 78712, USA.
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11
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Wang J, Song J, Clark G, Roux SJ. ANN1 and ANN2 Function in Post-Phloem Sugar Transport in Root Tips to Affect Primary Root Growth. Plant Physiol 2018; 178:390-401. [PMID: 30018170 PMCID: PMC6130020 DOI: 10.1104/pp.18.00713] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Accepted: 07/04/2018] [Indexed: 05/08/2023]
Abstract
Annexins are a multigene family of calcium-dependent membrane-binding proteins that play important roles in plant cell signaling. Annexins are multifunctional proteins, and their function in plants is not comprehensively understood. Arabidopsis (Arabidopsis thaliana) annexins ANN1 and ANN2 are 64% identical in their primary structure, and both are highly expressed in seedlings. Here, we showed that ann-mutant seedlings grown in the absence of sugar show decreased primary root growth and altered columella cells in root caps; however, these mutant defects are rescued by Suc, Glc, or Fru. In seedlings grown without sugar, significant up-regulation of photosynthetic gene expression and chlorophyll accumulation was found in ann-mutant cotyledons compared to that in wild type, which indicates potential sugar starvation in the roots of ann-mutant seedlings. Unexpectedly, the overall sugar content of ann-mutant primary roots was significantly higher than that of wild-type roots when grown without sugar. To examine the diffusion of sugar along the entire root to the root tip, we examined the unloading pattern of carboxyfluorescein dye and found that post-phloem sugar transport was impaired in ann-mutant root tips compared to that in wild type. Increased levels of ROS and callose were detected in the root tips of ann-mutant seedlings grown without Suc, the latter of which would restrict plasmodesmal sugar transport to root tips. Our results indicate that ANN1 and ANN2 play an important role in post-phloem sugar transport to the root tip, which in turn indirectly influences photosynthetic rates in cotyledons. This study expands our understanding of the function of annexins in plants.
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Affiliation(s)
- Jing Wang
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712
| | - Jawon Song
- Texas Advanced Computing Center, The University of Texas at Austin, Austin, Texas 78712
| | - Greg Clark
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712
| | - Stanley J Roux
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712
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12
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Kumar Tripathy M, Weeraratne G, Clark G, Roux SJ. Apyrase inhibitors enhance the ability of diverse fungicides to inhibit the growth of different plant-pathogenic fungi. Mol Plant Pathol 2017; 18:1012-1023. [PMID: 27392542 PMCID: PMC6638264 DOI: 10.1111/mpp.12458] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 06/24/2016] [Accepted: 07/06/2016] [Indexed: 06/06/2023]
Abstract
A previous study has demonstrated that the treatment of Arabidopsis plants with chemical inhibitors of apyrase enzymes increases their sensitivity to herbicides. In this study, we found that the addition of the same or related apyrase inhibitors could potentiate the ability of different fungicides to inhibit the growth of five different pathogenic fungi in plate growth assays. The growth of all five fungi was partially inhibited by three commonly used fungicides: copper octanoate, myclobutanil and propiconazole. However, when these fungicides were individually tested in combination with any one of four different apyrase inhibitors (AI.1, AI.10, AI.13 or AI.15), their potency to inhibit the growth of five fungal pathogens was increased significantly relative to their application alone. The apyrase inhibitors were most effective in potentiating the ability of copper octanoate to inhibit fungal growth, and least effective in combination with propiconazole. Among the five pathogens assayed, that most sensitive to the fungicide-potentiating effects of the inhibitors was Sclerotinia sclerotiorum. Overall, among the 60 treatment combinations tested (five pathogens, four apyrase inhibitors, three fungicides), the addition of apyrase inhibitors increased significantly the sensitivity of fungi to the fungicide treatments in 53 of the combinations. Consistent with their predicted mode of action, inhibitors AI.1, AI.10 and AI.13 each increased the level of propiconazole retained in one of the fungi, suggesting that they could partially block the ability of efflux transporters to remove propiconazole from these fungi.
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Affiliation(s)
- Manas Kumar Tripathy
- Department of Molecular BiosciencesUniversity of Texas at AustinAustinTX78712USA
| | - Gayani Weeraratne
- Department of Molecular BiosciencesUniversity of Texas at AustinAustinTX78712USA
| | - Greg Clark
- Department of Molecular BiosciencesUniversity of Texas at AustinAustinTX78712USA
| | - Stanley J. Roux
- Department of Molecular BiosciencesUniversity of Texas at AustinAustinTX78712USA
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13
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Park J, Salmi ML, Wan Salim WWA, Rademacher A, Wickizer B, Schooley A, Benton J, Cantero A, Argote PF, Ren M, Zhang M, Porterfield DM, Ricco AJ, Roux SJ, Rickus JL. An autonomous lab on a chip for space flight calibration of gravity-induced transcellular calcium polarization in single-cell fern spores. Lab Chip 2017; 17:1095-1103. [PMID: 28205656 DOI: 10.1039/c6lc01370h] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
This report describes the development of lab-on-a-chip device designed to measure changes in cellular ion gradients that are induced by changes in gravitational (g) forces. The bioCD presented here detects differential calcium ion concentrations outside of individual cells. The device includes sufficient replicates for statistical analysis of the gradients around multiple single cells and around control wells that are empty or include dead cells. In the data presented, the degree of the cellular response correlates with the magnitude of the g-force applied via rotation of the bioCD. The experiments recorded the longest continuous observation of a cellular response to hypergravity made to date, and they demonstrate the potential utility of this device for assaying the threshold of cells' g-force responses in spaceflight conditions.
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Affiliation(s)
- J Park
- Agricultural & Biological Engineering, Physiological Sensing Facility at the Bindley Bioscience Center & Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47907, USA.
| | - M L Salmi
- Molecular Biosciences, The University of Texas at Austin, 1 University Station A6700, Austin, TX 78712, USA
| | - W W A Wan Salim
- Agricultural & Biological Engineering, Physiological Sensing Facility at the Bindley Bioscience Center & Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47907, USA.
| | - A Rademacher
- NASA Ames Research Center, Moffett Field, CA 94035, USA
| | - B Wickizer
- NASA Ames Research Center, Moffett Field, CA 94035, USA
| | - A Schooley
- NASA Ames Research Center, Moffett Field, CA 94035, USA
| | - J Benton
- NASA Ames Research Center, Moffett Field, CA 94035, USA
| | - A Cantero
- Molecular Biosciences, The University of Texas at Austin, 1 University Station A6700, Austin, TX 78712, USA
| | - P F Argote
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - M Ren
- Dept of Statistics, Purdue University, West Lafayette, IN 47907, USA
| | - M Zhang
- Dept of Statistics, Purdue University, West Lafayette, IN 47907, USA
| | - D M Porterfield
- Agricultural & Biological Engineering, Physiological Sensing Facility at the Bindley Bioscience Center & Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47907, USA. and Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN 47907, USA
| | - A J Ricco
- NASA Ames Research Center, Moffett Field, CA 94035, USA
| | - S J Roux
- Molecular Biosciences, The University of Texas at Austin, 1 University Station A6700, Austin, TX 78712, USA
| | - J L Rickus
- Agricultural & Biological Engineering, Physiological Sensing Facility at the Bindley Bioscience Center & Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47907, USA. and Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA
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14
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Yang X, Wang B, Farris B, Clark G, Roux SJ. Modulation of Root Skewing in Arabidopsis by Apyrases and Extracellular ATP. Plant Cell Physiol 2015; 56:2197-206. [PMID: 26412783 DOI: 10.1093/pcp/pcv134] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 09/16/2015] [Indexed: 05/04/2023]
Abstract
When plant primary roots grow along a tilted surface that is impenetrable, they can undergo a slanted deviation from the direction of gravity called skewing. Skewing is induced by touch stimuli which the roots experience as they grow along the surface. Touch stimuli also induce the release of extracellular ATP (eATP) into the plant's extracellular matrix, and two apyrases (NTPDases) in Arabidopsis, APY1 and APY2, can help regulate the concentration of eATP. The primary roots of seedlings overexpressing APY1 show less skewing than wild-type plants. Plants suppressed in their expression of APY1 show more skewing than wild-type plants. Correspondingly, chemical inhibition of apyrase activity increased skewing in mutants and wild-type roots. Exogenous application of ATP or ATPγS also increased skewing in wild-type roots, which could be blocked by co-incubation with a purinergic receptor antagonist. These results suggest a model in which gradients of eATP set up by differential touch stimuli along roots help direct skewing in roots growing along an impenetrable surface.
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Affiliation(s)
- Xingyan Yang
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, Bioengineering College, Chongqing University, Chongqing, 400030, China
| | - Bochu Wang
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, Bioengineering College, Chongqing University, Chongqing, 400030, China
| | - Ben Farris
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA
| | - Greg Clark
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA
| | - Stanley J Roux
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA
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15
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Lee HS, Kim Y, Pham G, Kim JW, Song JH, Lee Y, Hwang YS, Roux SJ, Kim SH. Brassinazole resistant 1 (BZR1)-dependent brassinosteroid signalling pathway leads to ectopic activation of quiescent cell division and suppresses columella stem cell differentiation. J Exp Bot 2015; 66:4835-49. [PMID: 26136267 PMCID: PMC4507784 DOI: 10.1093/jxb/erv316] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Previous publications have shown that BRI1 EMS suppressor 1 (BES1), a positive regulator of the brassinosteroid (BR) signalling pathway, enhances cell divisions in the quiescent centre (QC) and stimulates columella stem cell differentiation. Here, it is demonstrated that BZR1, a BES1 homologue, also promotes cell divisions in the QC, but it suppresses columella stem cell differentiation, opposite to the action of BES1. In addition, BR and its BZR1-mediated signalling pathway are shown to alter the expression/subcellular distribution of pin-formed (PINs), which may result in changes in auxin movement. BR promotes intense nuclear accumulation of BZR1 in the root tip area, and the binding of BZR1 to the promoters of several root development-regulating genes, modulating their expression in the root stem cell niche area. These BZR1-mediated signalling cascades may account for both the ectopic activation of QC cell divisions as well as the suppression of the columella stem cell differentiation. They could also inhibit auxin-dependent distal stem cell differentiation by antagonizing the auxin/WOX5-dependent pathway. In conclusion, BZR1-/BES1-mediated BR signalling pathways show differential effects on the maintenance of root apical meristem activities: they stimulate ectopic QC division while they show opposite effects on the differentiation of distal columella stem cells in a BR concentration- and BZR1-/BES1-dependent manner.
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Affiliation(s)
- Hak-Soo Lee
- Division of Biological Science and Technology, Yonsei University, Wonju, 220-710, Republic of Korea
| | - Yoon Kim
- Division of Biological Science and Technology, Yonsei University, Wonju, 220-710, Republic of Korea
| | - Giang Pham
- Division of Biological Science and Technology, Yonsei University, Wonju, 220-710, Republic of Korea
| | - Ju Won Kim
- Division of Biological Science and Technology, Yonsei University, Wonju, 220-710, Republic of Korea
| | - Ji-Hye Song
- Division of Biological Science and Technology, Yonsei University, Wonju, 220-710, Republic of Korea
| | - Yew Lee
- Division of Biological Science and Technology, Yonsei University, Wonju, 220-710, Republic of Korea Department of Life Science, Hanyang University, Seoul, 133-791, Republic of Korea
| | - Yong-Sic Hwang
- Department of Bioscience and Biotechnology, Konkuk University, Seoul 143-701, Republic of Korea
| | - Stanley J Roux
- Department of Molecular Biosciences, University of Texas, Austin, TX 78712, USA
| | - Soo-Hwan Kim
- Division of Biological Science and Technology, Yonsei University, Wonju, 220-710, Republic of Korea
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16
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Cannon AE, Salmi ML, Bushart TJ, Roux SJ. Studying molecular changes during gravity perception and response in a single cell. Methods Mol Biol 2015; 1309:199-207. [PMID: 25981777 DOI: 10.1007/978-1-4939-2697-8_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
Early studies revealed a highly predictable pattern of gravity-directed growth and development in Ceratopteris richardii spores. This makes the spores a valuable model system for the study of how a single cell senses and responds to the force of gravity. Gravity regulates both the direction and magnitude of a trans-cell calcium current in germinating spores, and the orientation of this current predicts the polarization of spore development. Molecular techniques have been developed to evaluate the transcriptomic and proteomic profiles of spores before and after gravity establishes the polarity of their development. Here we describe these techniques, along with protocols for sterilizing the spores, sowing them in a solid or liquid growth media, and evaluating germination.
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Affiliation(s)
- Ashley E Cannon
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, 78712, USA
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17
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Sessa EB, Banks JA, Barker MS, Der JP, Duffy AM, Graham SW, Hasebe M, Langdale J, Li FW, Marchant DB, Pryer KM, Rothfels CJ, Roux SJ, Salmi ML, Sigel EM, Soltis DE, Soltis PS, Stevenson DW, Wolf PG. Between two fern genomes. Gigascience 2014; 3:15. [PMID: 25324969 PMCID: PMC4199785 DOI: 10.1186/2047-217x-3-15] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Accepted: 09/18/2014] [Indexed: 11/10/2022] Open
Abstract
Ferns are the only major lineage of vascular plants not represented by a sequenced nuclear genome. This lack of genome sequence information significantly impedes our ability to understand and reconstruct genome evolution not only in ferns, but across all land plants. Azolla and Ceratopteris are ideal and complementary candidates to be the first ferns to have their nuclear genomes sequenced. They differ dramatically in genome size, life history, and habit, and thus represent the immense diversity of extant ferns. Together, this pair of genomes will facilitate myriad large-scale comparative analyses across ferns and all land plants. Here we review the unique biological characteristics of ferns and describe a number of outstanding questions in plant biology that will benefit from the addition of ferns to the set of taxa with sequenced nuclear genomes. We explain why the fern clade is pivotal for understanding genome evolution across land plants, and we provide a rationale for how knowledge of fern genomes will enable progress in research beyond the ferns themselves.
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Affiliation(s)
- Emily B Sessa
- Department of Biology, Box 118525, University of Florida, Gainesville, FL 32611, USA ; Genetics Institute, University of Florida, Box 103610, Gainesville, FL 32611, USA
| | - Jo Ann Banks
- Department of Botany and Plant Pathology, Purdue University, 915 West State Street, West Lafayette, IN 47907, USA
| | - Michael S Barker
- Department of Ecology & Evolutionary Biology, University of Arizona, 1041 East Lowell Street, Tucson, AZ 85721, USA
| | - Joshua P Der
- Department of Biology, Penn State University, 201 Life Science Building, University Park, PA 16801, USA ; Current address: Department of Biological Science, California State University, 800 N. State College Blvd., Fullerton, CA 92831, USA
| | - Aaron M Duffy
- Ecology Center and Department of Biology, Utah State University, 5305 Old Main Hill, Logan, UT 84322, USA
| | - Sean W Graham
- Department of Botany, University of British Columbia, 3529-6720 University Blvd., Vancouver, BC V6T 1Z4, Canada
| | - Mitsuyasu Hasebe
- National Institute for Basic Biology, 38 Nishigounaka, Myo-daiji-cho, Okazaki 444-8585, Japan
| | - Jane Langdale
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK
| | - Fay-Wei Li
- Department of Biology, Duke University, Post Office Box 90338, Durham, NC 27708, USA
| | - D Blaine Marchant
- Department of Biology, Box 118525, University of Florida, Gainesville, FL 32611, USA ; Florida Museum of Natural History, Dickinson Hall, University of Florida, Gainesville, FL 32611, USA
| | - Kathleen M Pryer
- Department of Biology, Duke University, Post Office Box 90338, Durham, NC 27708, USA
| | - Carl J Rothfels
- Department of Zoology, University of British Columbia, 2329 W. Mall, WAITING Vancouver, BC V6T 1Z4, Canada ; Current address: University Herbarium and Department of Integrative Biology, University of California, 1001 Valley Life Sciences Building, Berkeley, Berkeley, CA 94720, USA
| | - Stanley J Roux
- Department of Molecular Biosciences, University of Texas, 205 W. 24th Street, Austin, TX 78712, USA
| | - Mari L Salmi
- Department of Molecular Biosciences, University of Texas, 205 W. 24th Street, Austin, TX 78712, USA
| | - Erin M Sigel
- Department of Biology, Duke University, Post Office Box 90338, Durham, NC 27708, USA
| | - Douglas E Soltis
- Department of Biology, Box 118525, University of Florida, Gainesville, FL 32611, USA ; Genetics Institute, University of Florida, Box 103610, Gainesville, FL 32611, USA ; Florida Museum of Natural History, Dickinson Hall, University of Florida, Gainesville, FL 32611, USA
| | - Pamela S Soltis
- Genetics Institute, University of Florida, Box 103610, Gainesville, FL 32611, USA ; Florida Museum of Natural History, Dickinson Hall, University of Florida, Gainesville, FL 32611, USA
| | - Dennis W Stevenson
- New York Botanical Garden, 2900 Southern Boulevard, Bronx, NY 10458, USA
| | - Paul G Wolf
- Ecology Center and Department of Biology, Utah State University, 5305 Old Main Hill, Logan, UT 84322, USA
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18
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Clark GB, Morgan RO, Fernandez MP, Salmi ML, Roux SJ. Breakthroughs spotlighting roles for extracellular nucleotides and apyrases in stress responses and growth and development. Plant Sci 2014; 225:107-116. [PMID: 25017166 DOI: 10.1016/j.plantsci.2014.06.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Revised: 05/31/2014] [Accepted: 06/02/2014] [Indexed: 06/03/2023]
Abstract
Animal and plant cells release nucleotides into their extracellular matrix when touched, wounded, and when their plasma membranes are stretched during delivery of secretory vesicles and growth. These released nucleotides then function as signaling agents that induce rapid increases in the concentration of cytosolic calcium, nitric oxide and superoxide. These, in turn, are transduced into downstream physiological changes. These changes in plants include changes in the growth of diverse tissues, in gravitropism, and in the opening and closing of stomates. The concentration of extracellular nucleotides is controlled by various phosphatases, prominent among which are apyrases EC 3.6.1.5 (nucleoside triphosphate diphosphohydrolases, NTPDases). This review provides phylogenetic and pHMM analyses of plant apyrases as well as analysis of predicted post-translational modifications for Arabidopsis apyrases. This review also summarizes and discusses recent advances in research on the roles of apyrases and extracellular nucleotides in controlling plant growth and development. These include new findings that document how apyrases and extracellular nucleotides control auxin transport, modulate stomatal aperture, and mediate biotic and abiotic stress responses, and on how apyrase suppression leads to growth inhibition.
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Affiliation(s)
- Greg B Clark
- Department of Molecular Biosciences, University of Texas, Austin, TX 78713, USA
| | - Reginald O Morgan
- Department of Biochemistry and Molecular Biology, Faculty of Medicine and University Institute of Biotechnology of Asturias, University of Oviedo, E-33006 Oviedo, Spain
| | - Maria-Pilar Fernandez
- Department of Biochemistry and Molecular Biology, Faculty of Medicine and University Institute of Biotechnology of Asturias, University of Oviedo, E-33006 Oviedo, Spain
| | - Mari L Salmi
- Department of Molecular Biosciences, University of Texas, Austin, TX 78713, USA
| | - Stanley J Roux
- Department of Molecular Biosciences, University of Texas, Austin, TX 78713, USA.
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19
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Roux SJ. A start point for extracellular nucleotide signaling. Mol Plant 2014; 7:937-938. [PMID: 24618880 DOI: 10.1093/mp/ssu023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Affiliation(s)
- Stanley J Roux
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA.
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20
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Lim MH, Wu J, Yao J, Gallardo IF, Dugger JW, Webb LJ, Huang J, Salmi ML, Song J, Clark G, Roux SJ. Apyrase suppression raises extracellular ATP levels and induces gene expression and cell wall changes characteristic of stress responses. Plant Physiol 2014; 164:2054-67. [PMID: 24550243 PMCID: PMC3982762 DOI: 10.1104/pp.113.233429] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Accepted: 02/13/2014] [Indexed: 05/20/2023]
Abstract
Plant cells release ATP into their extracellular matrix as they grow, and extracellular ATP (eATP) can modulate the rate of cell growth in diverse tissues. Two closely related apyrases (APYs) in Arabidopsis (Arabidopsis thaliana), APY1 and APY2, function, in part, to control the concentration of eATP. The expression of APY1/APY2 can be inhibited by RNA interference, and this suppression leads to an increase in the concentration of eATP in the extracellular medium and severely reduces growth. To clarify how the suppression of APY1 and APY2 is linked to growth inhibition, the gene expression changes that occur in seedlings when apyrase expression is suppressed were assayed by microarray and quantitative real-time-PCR analyses. The most significant gene expression changes induced by APY suppression were in genes involved in biotic stress responses, which include those genes regulating wall composition and extensibility. These expression changes predicted specific chemical changes in the walls of mutant seedlings, and two of these changes, wall lignification and decreased methyl ester bonds, were verified by direct analyses. Taken together, the results are consistent with the hypothesis that APY1, APY2, and eATP play important roles in the signaling steps that link biotic stresses to plant defense responses and growth changes.
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21
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Bushart TJ, Cannon A, Clark G, Roux SJ. Structure and function of CrACA1, the major PM-type Ca2+-ATPase, expressed at the peak of the gravity-directed trans-cell calcium current in spores of the fern Ceratopteris richardii. Plant Biol (Stuttg) 2014; 16 Suppl 1:151-7. [PMID: 24373013 DOI: 10.1111/plb.12107] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Accepted: 08/16/2013] [Indexed: 05/15/2023]
Abstract
Spores of the fern Ceratopteris richardii have proven to be a valuable single-cell system for studying gravity responses. The earliest cellular change directed by gravity in these cells is a trans-cell calcium current, which peaks near 10 h after the spores are induced to germinate. This current is needed for gravity-directed axis alignment, and its peak is coincident with the time period when gravity polarises the direction of subsequent nuclear migration and rhizoid growth. Transcriptomic analysis of genes expressed at the 10-h time point revealed several that encode proteins likely to be key components that either drive the current or regulate it. Notable among these is a plasma membrane (PM)-type Ca(2+) ATPase, CrACA1, whose activity pumping Ca(2+) out of cells is regulated by gravity. This report provides an initial characterisation of the structure and expression of this protein, and demonstrates its heterologous function complementing the K616 mutant of yeast, which is deficient in PM-type Ca(2+) pump activity. Gravity-induced changes in the trans-cell Ca(2+) current occur within seconds, a result consistent with the hypothesis that the force of gravity can rapidly alter the post-translational state of the channels and pumps that drive this current across spore cells. This report identifies a transporter likely to be a key driver of the current, CrACA1, and characterises the role of this protein in early germination and gravity-driven polarity fixation through analysis of expression levels, functional complementation and pharmacological treatments. These data, along with newly available transcriptomic data obtained at the 10-h time point, indicate that CrACA1 is present, functional and likely a major contributing component of the trans-cell Ca(2+) efflux. CrACA1 is not necessary for polar axis alignment, but pharmacological perturbations of it disrupt rhizoid development. These data support and help refine the post-translational modification model for gravity responses.
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Affiliation(s)
- T J Bushart
- Section of Molecular Cell & Developmental Biology, The University of Texas at Austin, Austin, TX, USA
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22
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Salmi ML, Clark G, Roux SJ. Current status and proposed roles for nitric oxide as a key mediator of the effects of extracellular nucleotides on plant growth. Front Plant Sci 2013; 4:427. [PMID: 24298275 PMCID: PMC3829461 DOI: 10.3389/fpls.2013.00427] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Accepted: 10/09/2013] [Indexed: 05/20/2023]
Abstract
Recent data indicate that nucleotides are released into the extracellular matrix during plant cell growth, and that these extracellular nucleotides induce signaling changes that can, in a dose-dependent manner, increase or decrease the cell growth. After activation of a presumed receptor, the earliest signaling change induced by extracellular nucleotides is an increase in the concentration of cytosolic Ca(2+), but rapidly following this change is an increase in the cellular level of nitric oxide (NO). In Arabidopsis, mutants deficient in nitrate reductase activity (nia1nia2) have drastically reduced nitric oxide production and cannot transduce the effects of applied nucleotides into growth changes. Both increased levels of extracellular nucleotides and increased NO production inhibit auxin transport and inhibit growth, and these effects are potentially due to disruption of the localization and/or function of auxin transport facilitators. However, because NO- and auxin-induced signaling pathways can intersect at multiple points, there may be diverse ways by which the induction of NO by extracellular ATP could modulate auxin signaling and thus influence growth. This review will discuss these optional mechanisms and suggest possible regulatory routes based on current experimental data and predictive computational analyses.
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Affiliation(s)
| | | | - Stanley J. Roux
- *Correspondence: Stanley J. Roux, Department of Molecular Biosciences, The University of Texas at Austin, 1 University Station A6700, 205 West 24th Street, BIO 16, Austin, TX 78712-0183, USA e-mail:
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23
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Yang J, Wu J, Romanovicz D, Clark G, Roux SJ. Co-regulation of exine wall patterning, pollen fertility and anther dehiscence by Arabidopsis apyrases 6 and 7. Plant Physiol Biochem 2013; 69:62-73. [PMID: 23728389 DOI: 10.1016/j.plaphy.2013.04.022] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Accepted: 04/29/2013] [Indexed: 05/02/2023]
Abstract
An NCBI nucleotide blast keyed to apyrase (ATP-diphosphohydrolases, EC 3.6.1.5) conserved regions revealed five apyrases, AtAPYs (3-7), in addition to the previously identified AtAPY1 and 2. Here we report the functional analyses of two of the newly defined apyrases, AtAPY6 and AtAPY7. We analyzed tissue specificity of AtAPY6 and 7 expression by qRT-PCR and promoter:GUS fusion assays. We characterized the phenotypes of single and double knockout mutants for AtAPY6 and 7 in anther and pollen by light microscopy and electron microscopy. The transcripts of both AtAPY6 and 7 are expressed in mature pollen grains. Single knockout mutants of AtAPY6 and 7 displayed a minor change in pollen exine pattern under scanning electron microscopy without obvious change in fertility. Double knockout mutants of AtAPY6 and 7 (apy6apy7) displayed severe defects in pollen exine pattern, deformed pollen shape and reduced male fertility. An analysis of pollen from heterozygous apy6apy7 plants suggests that the defects in pollen exine wall are determined by the diploid genome. Our findings demonstrate that AtAPY6 and AtAPY7 are enzymes that play an important role in exine development of pollen grains, possibly through regulating the production of key polysaccharides needed for proper assembly of the exine layer.
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Affiliation(s)
- Jian Yang
- Section of Molecular Cell and Developmental Biology, University of Texas at Austin, 1 University Station A6700, Austin TX 78712, USA
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24
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Bushart TJ, Cannon AE, Ul Haque A, San Miguel P, Mostajeran K, Clark GB, Porterfield DM, Roux SJ. RNA-seq analysis identifies potential modulators of gravity response in spores of Ceratopteris (Parkeriaceae): evidence for modulation by calcium pumps and apyrase activity. Am J Bot 2013; 100:161-74. [PMID: 23048014 DOI: 10.3732/ajb.1200292] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
PREMISE OF THE STUDY Gravity regulates the magnitude and direction of a trans-cell calcium current in germinating spores of Ceratopteris richardii. Blocking this current with nifedipine blocks the spore's downward polarity alignment, a polarization that is fixed by gravity ∼10 h after light induces the spores to germinate. RNA-seq analysis at 10 h was used to identify genes potentially important for the gravity response. The data set will be valuable for other developmental and phylogenetic studies. METHODS De novo Newbler assembly of 958 527 reads from Roche 454 sequencing was executed. The sequences were identified and analyzed using in silico methods. The roles of endomembrane Ca(2+)-ATPase pumps and apyrases in the gravity response were further tested using pharmacological agents. KEY RESULTS Transcripts related to calcium signaling and ethylene biosynthesis were identified as notable constituents of the transcriptome. Inhibiting the activity of endomembrane Ca(2+)-ATPase pumps with 2,5-di-(t-butyl)-1,4-hydroquinone diminished the trans-cell current, but increased the orientation of the polar axis to gravity. The effects of applied nucleotides and purinoceptor antagonists gave novel evidence implicating extracellular nucleotides as regulators of the gravity response in these fern spores. CONCLUSIONS In addition to revealing general features of the transcriptome of germinating spores, the results highlight a number of calcium-responsive and light-receptive transcripts. Pharmacologic assays indicate endomembrane Ca(2+)-ATPases and extracellular nucleotides may play regulatory roles in the gravity response of Ceratopteris spores.
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Affiliation(s)
- Thomas J Bushart
- The University of Texas at Austin, 1 University Station A6700, Austin, Texas 78712, USA
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25
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Abstract
Gravity has major effects on both the form and overall length of root growth. Numerous papers have documented these effects (over 300 publications in the last 5 years), the most well-studied being gravitropism, which is a growth re-orientation directed by gravity toward the earth's center. Less studied effects of gravity are undulations due to the regular periodic change in the direction root tips grow, called waving, and the slanted angle of growth roots exhibit when they are growing along a nearly-vertical surface, called skewing. Although diverse studies have led to the conclusion that a gravity stimulus is needed for plant roots to show waving and skewing, the novel results just published by Paul et al. (2012) reveal that this conclusion is not correct. In studies carried out in microgravity on the International Space Station, the authors used a new imaging system to collect digital photographs of plants every six hours during 15 days of spaceflight. The imaging system allowed them to observe how roots grew when their orientation was directed not by gravity but by overhead LED lights, which roots grew away from because they are negatively phototropic. Surprisingly, the authors observed both skewing and waving in spaceflight plants, thus demonstrating that both growth phenomena were gravity independent. Touch responses and differential auxin transport would be common features of root waving and skewing at 1-g and micro-g, and the novel results of Paul et al. will focus the attention of cell and molecular biologists more on these features as they try to decipher the signaling pathways that regulate root skewing and waving.
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Affiliation(s)
- Stanley J Roux
- Section of Molecular Cell and Developmental Biology, University of Texas, Austin, TX, USA
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Liu X, Wu J, Clark G, Lundy S, Lim M, Arnold D, Chan J, Tang W, Muday GK, Gardner G, Roux SJ. Role for apyrases in polar auxin transport in Arabidopsis. Plant Physiol 2012; 160:1985-95. [PMID: 23071251 PMCID: PMC3510125 DOI: 10.1104/pp.112.202887] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Accepted: 10/10/2012] [Indexed: 05/20/2023]
Abstract
Recent evidence indicates that extracellular nucleotides regulate plant growth. Exogenous ATP has been shown to block auxin transport and gravitropic growth in primary roots of Arabidopsis (Arabidopsis thaliana). Cells limit the concentration of extracellular ATP in part through the activity of ectoapyrases (ectonucleoside triphosphate diphosphohydrolases), and two nearly identical Arabidopsis apyrases, APY1 and APY2, appear to share this function. These findings, plus the fact that suppression of APY1 and APY2 blocks growth in Arabidopsis, suggested that the expression of these apyrases could influence auxin transport. This report tests that hypothesis. The polar movement of [(3)H]indole-3-acetic acid in both hypocotyl sections and primary roots of Arabidopsis seedlings was measured. In both tissues, polar auxin transport was significantly reduced in apy2 null mutants when they were induced by estradiol to suppress the expression of APY1 by RNA interference. In the hypocotyl assays, the basal halves of APY-suppressed hypocotyls contained considerably lower free indole-3-acetic acid levels when compared with wild-type plants, and disrupted auxin transport in the APY-suppressed roots was reflected by their significant morphological abnormalities. When a green fluorescent protein fluorescence signal encoded by a DR5:green fluorescent protein construct was measured in primary roots whose apyrase expression was suppressed either genetically or chemically, the roots showed no signal asymmetry following gravistimulation, and both their growth and gravitropic curvature were inhibited. Chemicals that suppress apyrase activity also inhibit gravitropic curvature and, to a lesser extent, growth. Taken together, these results indicate that a critical step connecting apyrase suppression to growth suppression is the inhibition of polar auxin transport.
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Chiu TY, Christiansen K, Moreno I, Lao J, Loqué D, Orellana A, Heazlewood JL, Clark G, Roux SJ. AtAPY1 and AtAPY2 function as Golgi-localized nucleoside diphosphatases in Arabidopsis thaliana. Plant Cell Physiol 2012; 53:1913-25. [PMID: 23034877 DOI: 10.1093/pcp/pcs131] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Nucleoside triphosphate diphosphohydrolases (NTPDases; apyrases) (EC 3.6.1.5) hydrolyze di- and triphosphate nucleotides, but not monophosphate nucleotides. They are categorized as E-type ATPases, have a broad divalent cation (Mg(2+), Ca(2+)) requirement for activation and are insensitive to inhibitors of F-type, P-type and V-type ATPases. Among the seven NTPDases identified in Arabidopsis, only APYRASE 1 (AtAPY1) and APYRASE 2 (AtAPY2) have been previously characterized. In this work, either AtAPY1 or AtAPY2 tagged with C-terminal green fluorescent protein (GFP) driven by their respective native promoter can rescue the apy1 apy2 double knockout (apy1 apy2 dKO) successfully, and confocal microscopy reveals that these two Arabidopsis apyrases reside in the Golgi apparatus. In Saccharomyces cerevisiae, both AtAPY1 and AtAPY2 can complement the Golgi-localized GDA1 mutant, rescuing its aberrant protein glycosylation phenotype. In Arabidopsis, microsomes of the wild type show higher substrate preferences toward UDP compared with other NDP substrates. Loss-of-function Arabidopsis AtAPY1 mutants exhibit reduced microsomal UDPase activity, and this activity is even more significantly reduced in the loss-of-function AtAPY2 mutant and in the AtAPY1/AtAPY2 RNA interference (RNAi) technology repressor lines. Microsomes from wild-type plants also have detectable GDPase activity, which is significantly reduced in apy2 but not apy1 mutants. The GFP-tagged AtAPY1 or AtAPY2 constructs in the apy1 apy2 dKO plants can restore microsomal UDP/GDPase activity, confirming that they both also have functional competency. The cell walls of apy1, apy2 and the RNAi-silenced lines all have an increased composition of galactose, but the transport efficiency of UDP-galactose across microsomal membranes was not altered. Taken together, these results reveal that AtAPY1 and AtAPY2 are Golgi-localized nucleotide diphosphatases and are likely to have roles in regulating UDP/GDP concentrations in the Golgi lumen.
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Affiliation(s)
- Tsan-Yu Chiu
- Section of Molecular Cell and Developmental Biology, University of Texas, Austin, TX 78712, USA
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Clark GB, Morgan RO, Fernandez MP, Roux SJ. Evolutionary adaptation of plant annexins has diversified their molecular structures, interactions and functional roles. New Phytol 2012; 196:695-712. [PMID: 22994944 DOI: 10.1111/j.1469-8137.2012.04308.x] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Accepted: 07/29/2012] [Indexed: 05/04/2023]
Abstract
Annexins are an homologous, structurally related superfamily of proteins known to associate with membrane lipid and cytoskeletal components. Their involvement in membrane organization, vesicle trafficking and signaling is fundamental to cellular processes such as growth, differentiation, secretion and repair. Annexins exist in some prokaryotes and all eukaryotic phyla within which plant annexins represent a monophyletic clade of homologs descended from green algae. Genomic, proteomic and transcriptomic approaches have provided data on the diversity, cellular localization and expression patterns of different plant annexins. The availability of 35 complete plant genomes has enabled systematic comparative analysis to determine phylogenetic relationships, characterize structures and observe functional specificity between and within individual subfamilies. Short amino termini and selective erosion of the canonical type 2 calcium coordinating sites in domains 2 and 3 are typical of plant annexins. The convergent evolution of alternate functional motifs such as 'KGD', redox-sensitive Cys and hydrophobic Trp/Phe residues argues for their functional relevance and contribution to mechanistic diversity in plant annexins. This review examines recent findings and advances in plant annexin research with special focus on their structural diversity, cellular and molecular interactions and their potential integrated functions in the broader context of physiological responses.
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Affiliation(s)
- Greg B Clark
- Section of Molecular Cell and Developmental Biology, University of Texas, Austin, TX, 78713, USA
| | - Reginald O Morgan
- Department of Biochemistry and Molecular Biology, Faculty of Medicine and University Institute of Biotechnology of Asturias, University of Oviedo, E-33006, Oviedo, Spain
| | - Maria-Pilar Fernandez
- Department of Biochemistry and Molecular Biology, Faculty of Medicine and University Institute of Biotechnology of Asturias, University of Oviedo, E-33006, Oviedo, Spain
| | - Stanley J Roux
- Section of Molecular Cell and Developmental Biology, University of Texas, Austin, TX, 78713, USA
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Jami SK, Clark GB, Ayele BT, Roux SJ, Kirti PB. Identification and characterization of annexin gene family in rice. Plant Cell Rep 2012; 31:813-825. [PMID: 22167239 DOI: 10.1007/s00299-011-1201-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Revised: 11/24/2011] [Accepted: 11/29/2011] [Indexed: 05/31/2023]
Abstract
Plant annexins are Ca(2+)-dependent phospholipid-binding proteins and are encoded by multigene families. They are implicated in the regulation of plant development as well as protection from drought and other stresses. They are well characterized in Arabidopsis, however no such characterization of rice annexin gene family has been reported thus far. With the availability of the rice genome sequence information, we have identified ten members of the rice annexin gene family. At the protein level, they share 16-64% identity with predicted molecular masses ranging from 32 to 40 kDa. Phylogenetic analysis of rice annexins together with annexins from other monocots led to their classification into five different orthologous groups and share similar motif patterns in their protein sequences. Expression analysis by real-time RT-PCR revealed differential temporal and spatial regulation of these genes. The rice annexin genes are also found to be regulated in seedling stage by various abiotic stressors including salinity, drought, heat and cold. Additionally, in silico analysis of the putative upstream sequences was analyzed for the presence of stress-responsive cis-elements. These results provide a basis for further functional characterization of specific rice annexin genes at the tissue/developmental level and in response to abiotic stresses.
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Affiliation(s)
- Sravan Kumar Jami
- Department of Plant Science, University of Manitoba, Winnipeg, MB R3T 2N2, Canada.
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Clark G, Roux SJ. Apyrases, extracellular ATP and the regulation of growth. Curr Opin Plant Biol 2011; 14:700-6. [PMID: 21855397 DOI: 10.1016/j.pbi.2011.07.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Revised: 07/15/2011] [Accepted: 07/23/2011] [Indexed: 05/07/2023]
Abstract
Although no definitive receptor for extracellular ATP (eATP) has been identified in plants, there is now stronger physiological evidence that the effects of eATP on plant growth are mediated by a receptor, or, as in animals, by multiple receptors. Recent papers clarify how extracellular nucleotides induce changes in [Ca(2+)](cyt), and the production of nitric oxide (NO) and reactive oxygen species. They document links between eATP signaling and the synthesis or transport of hormones, and they reveal that applied nucleotides can regulate the aperture of stomates, which release ATP when stimulated by light and hormones. Ectoapyrases (ecto-nucleoside triphosphate-diphosphohydrolase) help control both the diverse signaling changes and downstream growth changes induced by extracellular nucleotides by limiting their concentration in the extracellular matrix (ECM).
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Affiliation(s)
- Greg Clark
- Section of Molecular Cell and Developmental Biology, University of Texas, Austin, TX 78712, USA
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Clark G, Fraley D, Steinebrunner I, Cervantes A, Onyirimba J, Liu A, Torres J, Tang W, Kim J, Roux SJ. Extracellular nucleotides and apyrases regulate stomatal aperture in Arabidopsis. Plant Physiol 2011; 156:1740-53. [PMID: 21636723 PMCID: PMC3149927 DOI: 10.1104/pp.111.174466] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2011] [Accepted: 05/31/2011] [Indexed: 05/19/2023]
Abstract
This study investigates the role of extracellular nucleotides and apyrase enzymes in regulating stomatal aperture. Prior data indicate that the expression of two apyrases in Arabidopsis (Arabidopsis thaliana), APY1 and APY2, is strongly correlated with cell growth and secretory activity. Both are expressed strongly in guard cell protoplasts, as determined by reverse transcription-polymerase chain reaction and immunoblot analyses. Promoter activity assays for APY1 and APY2 show that expression of both apyrases correlates with conditions that favor stomatal opening. Correspondingly, immunoblot data indicate that APY expression in guard cell protoplasts rises quickly when these cells are moved from darkness into light. Both short-term inhibition of ectoapyrase activity by polyclonal antibodies and long-term suppression of APY1 and APY2 transcript levels significantly disrupt normal stomatal behavior in light. Stomatal aperture shows a biphasic response to applied adenosine 5'-[γ-thio]triphosphate (ATPγS) or adenosine 5'-[β-thio] diphosphate, with lower concentrations inducing stomatal opening and higher concentrations inducing closure. Equivalent concentrations of adenosine 5'-O-thiomonophosphate have no effect on aperture. Two mammalian purinoceptor inhibitors block ATPγS- and adenosine 5'-[β-thio] diphosphate-induced opening and closing and also partially block the ability of abscisic acid to induce stomatal closure and of light to induce stomatal opening. Treatment of epidermal peels with ATPγS induces increased levels of nitric oxide and reactive oxygen species, and genetically suppressing the synthesis of these agents blocks the effects of nucleotides on stomatal aperture. A luciferase assay indicates that treatments that induce either the closing or opening of stomates also induce the release of ATP from guard cells. These data favor the novel conclusion that ectoapyrases and extracellular nucleotides play key roles in regulating stomatal functions.
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Affiliation(s)
- Greg Clark
- Section of Molecular, Cell, and Developmental Biology, University of Texas, Austin, Texas 78712, USA
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Salmi ML, ul Haque A, Bushart TJ, Stout SC, Roux SJ, Porterfield DM. Changes in gravity rapidly alter the magnitude and direction of a cellular calcium current. Planta 2011. [PMID: 21234599 DOI: 10.1007/s00425-010-1343-1342] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
In single-celled spores of the fern Ceratopteris richardii, gravity directs polarity of development and induces a directional, trans-cellular calcium (Ca(2+)) current. To clarify how gravity polarizes this electrophysiological process, we measured the kinetics of the cellular response to changes in the gravity vector, which we initially estimated using the self-referencing calcium microsensor. In order to generate more precise and detailed data, we developed a silicon microfabricated sensor array which facilitated a lab-on-a-chip approach to simultaneously measure calcium currents from multiple cells in real time. These experiments revealed that the direction of the gravity-dependent polar calcium current is reversed in less than 25 s when the cells are inverted, and that changes in the magnitude of the calcium current parallel rapidly changing g-forces during parabolic flight on the NASA C-9 aircraft. The data also revealed a hysteresis in the response of cells in the transition from 2g to micro-g in comparison to cells in the micro-g to 2-g transition, a result consistent with a role for mechanosensitive ion channels in the gravity response. The calcium current is suppressed by either nifedipine (calcium-channel blocker) or eosin yellow (plasma membrane calcium pump inhibitor). Nifedipine disrupts gravity-directed cell polarity, but not spore germination. These results indicate that gravity perception in single plant cells may be mediated by mechanosensitive calcium channels, an idea consistent with some previously proposed models of plant gravity perception.
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Affiliation(s)
- Mari L Salmi
- Molecular Cell and Developmental Biology, University of Texas, Austin, TX 78712, USA
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33
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Salmi ML, ul Haque A, Bushart TJ, Stout SC, Roux SJ, Porterfield DM. Changes in gravity rapidly alter the magnitude and direction of a cellular calcium current. Planta 2011; 233:911-20. [PMID: 21234599 DOI: 10.1007/s00425-010-1343-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2010] [Accepted: 12/21/2010] [Indexed: 05/21/2023]
Abstract
In single-celled spores of the fern Ceratopteris richardii, gravity directs polarity of development and induces a directional, trans-cellular calcium (Ca(2+)) current. To clarify how gravity polarizes this electrophysiological process, we measured the kinetics of the cellular response to changes in the gravity vector, which we initially estimated using the self-referencing calcium microsensor. In order to generate more precise and detailed data, we developed a silicon microfabricated sensor array which facilitated a lab-on-a-chip approach to simultaneously measure calcium currents from multiple cells in real time. These experiments revealed that the direction of the gravity-dependent polar calcium current is reversed in less than 25 s when the cells are inverted, and that changes in the magnitude of the calcium current parallel rapidly changing g-forces during parabolic flight on the NASA C-9 aircraft. The data also revealed a hysteresis in the response of cells in the transition from 2g to micro-g in comparison to cells in the micro-g to 2-g transition, a result consistent with a role for mechanosensitive ion channels in the gravity response. The calcium current is suppressed by either nifedipine (calcium-channel blocker) or eosin yellow (plasma membrane calcium pump inhibitor). Nifedipine disrupts gravity-directed cell polarity, but not spore germination. These results indicate that gravity perception in single plant cells may be mediated by mechanosensitive calcium channels, an idea consistent with some previously proposed models of plant gravity perception.
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Affiliation(s)
- Mari L Salmi
- Molecular Cell and Developmental Biology, University of Texas, Austin, TX 78712, USA
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34
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Clark G, Wu M, Wat N, Onyirimba J, Pham T, Herz N, Ogoti J, Gomez D, Canales AA, Aranda G, Blizard M, Nyberg T, Terry A, Torres J, Wu J, Roux SJ. Both the stimulation and inhibition of root hair growth induced by extracellular nucleotides in Arabidopsis are mediated by nitric oxide and reactive oxygen species. Plant Mol Biol 2010; 74:423-35. [PMID: 20820881 DOI: 10.1007/s11103-010-9683-7] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2010] [Accepted: 08/24/2010] [Indexed: 05/20/2023]
Abstract
Root hairs secrete ATP as they grow, and extracellular ATP and ADP can trigger signaling pathways that regulate plant cell growth. In several plant tissues the level of extracellular nucleotides is limited in part by ectoapyrases (ecto-NTPDases), and the growth of these tissues is strongly influenced by their level of ectoapyrase expression. Both chemical inhibition of ectoapyrase activity and suppression of the expression of two ectoapyrase enzymes by RNAi in Arabidopsis resulted in inhibition of root hair growth. As assayed by a dose-response curve, different concentrations of the poorly hydrolysable nucleotides, ATPγS and ADPβS, could either stimulate (at 7.5-25 μM) or inhibit (at ≥ 150 μM) the growth rate of root hairs in less than an hour. Equal amounts of AMPS, used as a control, had no effect on root hair growth. Root hairs of nia1nia2 mutants, which are suppressed in nitric oxide (NO) production, and of atrbohD/F mutants, which are suppressed in the production of H(2)O(2), did not show growth responses to applied nucleotides, indicating that the growth changes induced by these nucleotides in wild-type plants were likely transduced via NO and H(2)O(2) signals. Consistent with this interpretation, treatment of root hairs with different concentrations of ATPγS induced different accumulations of NO and H(2)O(2) in root hair tips. Two mammalian purinoceptor antagonists also blocked the growth responses induced by extracellular nucleotides, suggesting that they were initiated by a receptor-based mechanism.
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Affiliation(s)
- Greg Clark
- Section of Molecular Cell and Developmental Biology, University of Texas, 78712, Austin, TX, USA
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Roux SJ, McEntire K, Slocum RD, Cedel TE, Hale CC. Phytochrome induces photoreversible calcium fluxes in a purified mitochondrial fraction from oats. Proc Natl Acad Sci U S A 2010; 78:283-7. [PMID: 16592951 PMCID: PMC319037 DOI: 10.1073/pnas.78.1.283] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Previous studies have indicated that phytochrome regulates Ca(2+) fluxes across the plasma membrane of plant cells. In this study we investigated whether phytochrome can also regulate such fluxes across mitochondrial membranes, using the Ca(2+)-sensitive dye murexide to monitor the uptake and release of Ca(2+) by mitochondria. The results showed that Ca(2+) fluxes in these organelles could be photoreversibly altered, red light diminishing the net uptake rate and far-red light restoring this rate to its dark control level. Treatment of the mitochondria with ruthenium red blocked their Ca(2+) uptake. In the presence of this inhibitor, red light induced a net efflux of Ca(2+) from the mitochondria, and subsequent far-red light reduced this efflux to nearly zero, the dark control level. Light-induced rate changes in Ca(2+) flux, both with and without the inhibitor, persisted for several minutes in the dark and remained photoreversible through several irradiations for as long as 30 min. The purity of the mitochondrial preparation was judged to be about 80% by electron microscopic morphometry; most of the phytochrome present was localized on the mitochondria in the preparation by using immunocytochemical methods. Taken together with previous findings, the results suggest that red light activation of phytochrome would initiate an increase in the cytosolic Ca(2+) concentration. The results are integrated with the fact that calmodulin is a component of plant cell cytoplasms to construct a model postulating that phytochrome directs photomorphogenesis in part through its regulation of Ca(2+) and calmodulin-controlled enzyme activities.
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Affiliation(s)
- S J Roux
- Department of Botany and Cell Research Institute, The University of Texas at Austin, Austin, Texas 78712
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36
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Georgevich G, Cedel TE, Roux SJ. Use of I-labeled phytochrome to quantitate phytochrome binding to membranes of Avena sativa. Proc Natl Acad Sci U S A 2010; 74:4439-43. [PMID: 16592450 PMCID: PMC431958 DOI: 10.1073/pnas.74.10.4439] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Purified oat phytochrome was labeled with (125)I without altering the photoreversibility or absorbance properties of the pigment. The radiolabeled phytochrome was used in experiments in vitro to quantitate the binding of the pigment to both crude and purified membrane preparations from oat tissue. After the membranes were allowed to react with (125)I-labeled phytochrome, washed free of unbound material, and pelleted, they were found to have significant levels of radioactivity bound to them. Qualitative identification of phytochrome as the bound radioactive species was confirmed by autoradiography of sodium dodecyl sulfate gels after electrophoresis of the proteins contained in the washed membranes. Data supporting the specificity of the binding are that the binding shows saturation kinetics and that unlabeled phytochrome, but not bovine serum albumin, will competitively inhibit the binding of labeled phytochrome. This technique permits the detection of less than a nanogram of phytochrome and provides a new method for quantifying bound phytochrome that is independent of the spectral detectability of the pigment. It should be useful in elucidating the nature of phytochrome attachment to cellular membranes.
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Affiliation(s)
- G Georgevich
- Department of Life Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260
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Clark G, Torres J, Finlayson S, Guan X, Handley C, Lee J, Kays JE, Chen ZJ, Roux SJ. Apyrase (nucleoside triphosphate-diphosphohydrolase) and extracellular nucleotides regulate cotton fiber elongation in cultured ovules. Plant Physiol 2010; 152:1073-83. [PMID: 20018604 PMCID: PMC2815863 DOI: 10.1104/pp.109.147637] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2009] [Accepted: 12/08/2009] [Indexed: 05/20/2023]
Abstract
Ectoapyrase enzymes remove the terminal phosphate from extracellular nucleoside tri- and diphosphates. In Arabidopsis (Arabidopsis thaliana), two ectoapyrases, AtAPY1 and AtAPY2, have been implicated as key modulators of growth. In fibers of cotton (Gossypium hirsutum), transcript levels for GhAPY1 and GhAPY2, two closely related ectoapyrases that have high sequence similarity to AtAPY1 and AtAPY2, are up-regulated when fibers enter their rapid growth phase. In an ovule culture system, fibers release ATP as they grow, and when their ectoapyrase activity is blocked by the addition of polyclonal anti-apyrase antibodies or by two different small molecule inhibitors, the medium ATP level rises and fiber growth is suppressed. High concentrations of the poorly hydrolyzable nucleotides ATPgammaS and ADPbetaS applied to the medium inhibit fiber growth, and low concentrations of them stimulate growth, but treatment with adenosine 5'-O-thiomonophosphate causes no change in the growth rate. Both the inhibition and stimulation of growth by applied nucleotides can be blocked by an antagonist that blocks purinoceptors in animal cells, and by adenosine. Treatment of cotton ovule cultures with ATPgammaS induces increased levels of ethylene, and two ethylene antagonists, aminovinylglycine and silver nitrate, block both the growth stimulatory and growth inhibitory effects of applied nucleotides. In addition, the ethylene precursor, 1-aminocyclopropane-1-carboxylic acid, lowers the concentration of nucleotide needed to promote fiber growth. These data indicate that ectoapyrases and extracellular nucleotides play a significant role in regulating cotton fiber growth and that ethylene is a likely downstream component of the signaling pathway.
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Reichler SA, Torres J, Rivera AL, Cintolesi VA, Clark G, Roux SJ. Intersection of two signalling pathways: extracellular nucleotides regulate pollen germination and pollen tube growth via nitric oxide. J Exp Bot 2009; 60:2129-38. [PMID: 19363208 PMCID: PMC2682505 DOI: 10.1093/jxb/erp091] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2008] [Revised: 03/02/2009] [Accepted: 03/02/2009] [Indexed: 05/18/2023]
Abstract
Plant and animal cells release or secrete ATP by various mechanisms, and this activity allows extracellular ATP to serve as a signalling molecule. Recent reports suggest that extracellular ATP induces plant responses ranging from increased cytosolic calcium to changes in auxin transport, xenobiotic resistance, pollen germination, and growth. Although calcium has been identified as a secondary messenger for the extracellular ATP signal, other parts of this signal transduction chain remain unknown. Increasing the extracellular concentration of ATPgammaS, a poorly-hydrolysable ATP analogue, inhibited both pollen germination and pollen tube elongation, while the addition of AMPS had no effect. Because pollen tube elongation is also sensitive to nitric oxide, this raised the possibility that a connection exists between the two pathways. Four approaches were used to test whether the germination and growth effects of extracellular ATPgammaS were transduced via nitric oxide. The results showed that increases in extracellular ATPgammaS induced increases in cellular nitric oxide, chemical agonists of the nitric oxide signalling pathway lowered the threshold of extracellular ATPgammaS that inhibits pollen germination, an antagonist of guanylate cyclase, which can inhibit some nitric oxide signalling pathways, blocked the ATPgammaS-induced inhibition of both pollen germination and pollen tube elongation, and the effects of applied ATPgammaS were blocked in nia1nia2 mutants, which have diminished NO production. The concurrence of these four data sets support the conclusion that the suppression of pollen germination and pollen tube elongation by extracellular nucleotides is mediated in part via the nitric oxide signalling pathway.
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Salmi ML, Roux SJ. Gene expression changes induced by space flight in single-cells of the fern Ceratopteris richardii. Planta 2008; 229:151-9. [PMID: 18807069 DOI: 10.1007/s00425-008-0817-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2008] [Accepted: 09/03/2008] [Indexed: 05/10/2023]
Abstract
This work describes a rare high-throughput evaluation of gene expression changes induced by space flight in a single plant cell. The cell evaluated is the spore of the fern Ceratopteris richardii, which exhibits both perception and response to gravity. cDNA microarray and Q RT-PCR analysis of spores germinating in microgravity onboard NASA space shuttle flight STS-93 revealed changes in the mRNA expression of roughly 5% of genes analyzed. These gene expression changes were compared with gene expression changes that occur during gravity perception and response in animal cells and multicellular plants. Our data contribute to a better understanding of the impact of space flight conditions, including microgravity, on cellular growth and development, and provide insights into the adaptive strategies of individual cells in response to these conditions.
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Affiliation(s)
- Mari L Salmi
- Section of Molecular Cell and Developmental Biology, The University of Texas at Austin, 1 University Station A6700, Austin, TX 78712-0183, USA
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Torres J, Rivera A, Clark G, Roux SJ. PARTICIPATION OF EXTRACELLULAR NUCLEOTIDES IN THE WOUND RESPONSE OF DASYCLADUS VERMICULARIS AND ACETABULARIA ACETABULUM (DASYCLADALES, CHLOROPHYTA)(1). J Phycol 2008; 44:1504-11. [PMID: 27039864 DOI: 10.1111/j.1529-8817.2008.00602.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
As assayed by fluorescent reporter dyes, nitric oxide (NO) and H2 O2 , two downstream signaling agents induced by wounding in the alga Dasycladus vermicularis (Scop.) Krasser, can also be induced in unwounded Dasycladus cells by μM Adenosine 5'[γ-thio]triphosphate (ATPγS) and Adenosine 5'-[β-thio]diphosphate (ADPβS), but not by Adenosine 5'-O-thiomonophosphate (AMPS). These nucleotide-induced responses are blocked by pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS), an antagonist of animal purinoceptors, and by adenosine, a feed-back inhibitor of extracellular nucleotide responses in animals. Similar nucleotide- and nucleotide-antagonist responses were observed in Acetabularia acetabulum (L.) P. C. Silva. Significant levels of ATP released from Dasycladus cells were measured at wound sites by a sensitive luciferin-luciferase assay. Additionally, the normal wound-induced production of NO and H2 O2 in Dasycladus can be blocked by pretreating the cells with PPADS. Our results indicate that nucleotides released from wounds can serve as a signal to trigger wound responses in algae, and that coordinated signaling between extracellular nucleotides and the NO pathway may have been established early during the evolution of plants.
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Affiliation(s)
- Jonathan Torres
- Section of Molecular Cell and Developmental Biology, University of Texas, Austin, Texas 78712, USA
| | - Amy Rivera
- Section of Molecular Cell and Developmental Biology, University of Texas, Austin, Texas 78712, USA
| | - Greg Clark
- Section of Molecular Cell and Developmental Biology, University of Texas, Austin, Texas 78712, USA
| | - Stanley J Roux
- Section of Molecular Cell and Developmental Biology, University of Texas, Austin, Texas 78712, USA
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Jami SK, Clark GB, Turlapati SA, Handley C, Roux SJ, Kirti PB. Ectopic expression of an annexin from Brassica juncea confers tolerance to abiotic and biotic stress treatments in transgenic tobacco. Plant Physiol Biochem 2008; 46:1019-30. [PMID: 18768323 DOI: 10.1016/j.plaphy.2008.07.006] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2008] [Accepted: 07/10/2008] [Indexed: 05/18/2023]
Abstract
Plant annexins belong to a multigene family and are suggested to play a role in stress responses. A full-length cDNA for a gene encoding an annexin protein was isolated and characterized from Brassica juncea (AnnBj1). AnnBj1 message levels were regulated by abscisic acid, ethephon, salicylic acid, and methyl jasmonate as well as chemicals that induce osmotic stress (NaCl, Mannitol or PEG), heavy metal stress (CdCl(2)) and oxidative stress (methyl viologen or H(2)O(2)). In order to determine if AnnBj1 functions in protection against stress, we generated transgenic tobacco plants ectopically expressing AnnBj1 under the control of constitutive CaMV 35S promoter. The transgenic tobacco plants showed significant tolerance to dehydration (mannitol), salt (NaCl), heavy metal (CdCl(2)) and oxidative stress (H(2)O(2)) at the seedling stage and retained higher chlorophyll levels in response to the above stresses as determined in detached leaf senescence assays. The transgenic plants also showed decreased accumulation of thiobarbituric acid-reactive substances (TBARS) compared to wild-type plants in response to mannitol treatments in leaf disc assays. AnnBj1 recombinant protein exhibited low levels of peroxidase activity in vitro and transgenic plants showed increased total peroxidase activity. Additionally, the transgenic plants showed enhanced resistance to the oomycete pathogen, Phytophthora parasitica var. nicotianae, and increased message levels for several pathogenesis-related proteins. Our results demonstrate that ectopic expression of AnnBj1 in tobacco provides tolerance to a variety of abiotic and biotic stresses.
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Affiliation(s)
- Sravan Kumar Jami
- Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad-500046, AP, India
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Yao J, Chang C, Salmi ML, Hung YS, Loraine A, Roux SJ. Genome-scale cluster analysis of replicated microarrays using shrinkage correlation coefficient. BMC Bioinformatics 2008; 9:288. [PMID: 18564431 PMCID: PMC2459189 DOI: 10.1186/1471-2105-9-288] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2007] [Accepted: 06/18/2008] [Indexed: 11/10/2022] Open
Abstract
Background Currently, clustering with some form of correlation coefficient as the gene similarity metric has become a popular method for profiling genomic data. The Pearson correlation coefficient and the standard deviation (SD)-weighted correlation coefficient are the two most widely-used correlations as the similarity metrics in clustering microarray data. However, these two correlations are not optimal for analyzing replicated microarray data generated by most laboratories. An effective correlation coefficient is needed to provide statistically sufficient analysis of replicated microarray data. Results In this study, we describe a novel correlation coefficient, shrinkage correlation coefficient (SCC), that fully exploits the similarity between the replicated microarray experimental samples. The methodology considers both the number of replicates and the variance within each experimental group in clustering expression data, and provides a robust statistical estimation of the error of replicated microarray data. The value of SCC is revealed by its comparison with two other correlation coefficients that are currently the most widely-used (Pearson correlation coefficient and SD-weighted correlation coefficient) using statistical measures on both synthetic expression data as well as real gene expression data from Saccharomyces cerevisiae. Two leading clustering methods, hierarchical and k-means clustering were applied for the comparison. The comparison indicated that using SCC achieves better clustering performance. Applying SCC-based hierarchical clustering to the replicated microarray data obtained from germinating spores of the fern Ceratopteris richardii, we discovered two clusters of genes with shared expression patterns during spore germination. Functional analysis suggested that some of the genetic mechanisms that control germination in such diverse plant lineages as mosses and angiosperms are also conserved among ferns. Conclusion This study shows that SCC is an alternative to the Pearson correlation coefficient and the SD-weighted correlation coefficient, and is particularly useful for clustering replicated microarray data. This computational approach should be generally useful for proteomic data or other high-throughput analysis methodology.
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Affiliation(s)
- Jianchao Yao
- Institute for Cellular and Molecular Biology and Department of Mathematics, University of Texas at Austin, Austin, Texas 78712, USA.
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Roux SJ, Steinebrunner I. Extracellular ATP: an unexpected role as a signaler in plants. Trends Plant Sci 2007; 12:522-527. [PMID: 17928260 DOI: 10.1016/j.tplants.2007.09.003] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2007] [Revised: 08/14/2007] [Accepted: 09/25/2007] [Indexed: 05/04/2023]
Abstract
ATP and other nucleoside triphosphates not only drive energy-dependent reactions inside cells, but can also function outside the plasma membrane in the extracellular matrix, where they function as agonists that can induce diverse physiological responses without being hydrolyzed. This external role of ATP is well established in animal cells but only recently has it become apparent that extracellular ATP (eATP) can also function as a signaling agent in plants. Recent data have shown that eATP and other nucleotides can induce an increase in the cytosolic Ca(2+) concentration and diverse downstream changes that influence plant growth and defense responses. Ectoapyrase enzymes that regulate the eATP concentration also have an impact on plant growth. These results beg the question of whether there is a receptor that can bind to eATP and transduce this into signaling changes. Answering this will be key to understanding how eATP and ectoapyrases influence plant growth and development.
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Affiliation(s)
- Stanley J Roux
- Section of Molecular Cell & Developmental Biology, The University of Texas at Austin, Austin, TX 78712, USA.
| | - Iris Steinebrunner
- Section of Molecular Biotechnology, Technical University of Dresden, 01069 Dresden, Germany
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Lee Y, Roux SJ, Kim SH. Biochemical characterization of a family of proteins that stabilizes a plant Ran protein in its GTP-bound conformation. Plant Physiol Biochem 2007; 45:515-20. [PMID: 17433702 DOI: 10.1016/j.plaphy.2007.03.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2006] [Accepted: 03/05/2007] [Indexed: 05/14/2023]
Abstract
Ran-binding proteins (RanBP) are a group of proteins that bind to Ran (Ras-related nuclear small G-protein) and thus control the GTP/GDP-bound states of the Ran and couple the Ran GTPase cycle to cellular processes. In an effort to identify potential downstream effectors for PsRan1-dependent cellular processes, we detected a group of pea Ran (PsRan1)-binding proteins and characterized their biochemical activities. A Ran overlay assay using [(32)P-GTP]-labeled PsRan1 revealed three PsRan1-binding proteins (33, 45, and 85kDa in size) from total protein extracts of dark-grown pea plumules. These proteins bound preferentially to the Ran-GTP over Ran-GDP conformation and subsequently stabilized its GTP-bound status. We propose that they are a family of proteins that maintain the Ran protein in the active conformation and are potential downstream mediators for PsRan1-dependent cellular processes. Our report provides the basis for characterizing and dissecting Ran downstream targets and Ran-mediated events, and it thus facilitates our understanding about the roles played by Ran/RanBP signaling pathways during plant growth and development.
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Affiliation(s)
- Y Lee
- Department of Biological Sciences, Yonsei University, 234 Heungup-Myun, 220710 Wonju-Si, Korea
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Wu J, Steinebrunner I, Sun Y, Butterfield T, Torres J, Arnold D, Gonzalez A, Jacob F, Reichler S, Roux SJ. Apyrases (nucleoside triphosphate-diphosphohydrolases) play a key role in growth control in Arabidopsis. Plant Physiol 2007; 144:961-75. [PMID: 17434987 PMCID: PMC1914212 DOI: 10.1104/pp.107.097568] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Expression of two Arabidopsis (Arabidopsis thaliana) apyrase (nucleoside triphosphate-diphosphohydrolase) genes with high similarity, APY1 and APY2, was analyzed during seedling development and under different light treatments using beta-glucuronidase fusion constructs with the promoters of both genes. As evaluated by beta-glucuronidase staining and independently confirmed by other methods, the highest expression of both apyrases was in rapidly growing tissues and/or tissues that accumulate high auxin levels. Red-light treatment of etiolated seedlings suppressed the protein and message level of both apyrases at least as rapidly as it inhibited hypocotyl growth. Adult apy1 and apy2 single mutants had near-normal growth, but apy1apy2 double-knockout plants were dwarf, due primarily to reduced cell elongation. Pollen tubes and etiolated hypocotyls overexpressing an apyrase had faster growth rates than wild-type plants. Growing pollen tubes released ATP into the growth medium and suppression of apyrase activity by antiapyrase antibodies or by inhibitors simultaneously increased medium ATP levels and inhibited pollen tube growth. These results imply that APY1 and APY2, like their homologs in animals, act to reduce the concentration of extracellular nucleotides, and that this function is important for the regulation of growth in Arabidopsis.
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Affiliation(s)
- Jian Wu
- Section of Molecular Cell and Developmental Biology, University of Texas, Austin, Texas 78712, USA
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Salmi ML, Morris KE, Roux SJ, Porterfield DM. Nitric oxide and cGMP signaling in calcium-dependent development of cell polarity in Ceratopteris richardii. Plant Physiol 2007; 144:94-104. [PMID: 17351052 PMCID: PMC1913794 DOI: 10.1104/pp.107.096131] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Single-celled spores of the fern Ceratopteris richardii undergo gravity-directed cell polarity development that is driven by polar calcium currents. Here we present results that establish a role for nitric oxide (NO)/cGMP signaling in transducing the stimulus of gravity to directed polarization of the spores. Application of specific NO donors and scavengers inhibited the calcium-dependent gravity response in a dose-dependent manner. The effects of NO donor exposure were antagonized by application of NO scavenger compounds. Similarly, the guanylate cyclase inhibitors 6-anilino-5,8-quinolinedione and 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin, and the phosphodiesterase inhibitor Viagra, which modulate NO-dependent cGMP levels in the cells, disrupted gravity-directed cell polarity in a dose-dependent manner. Viagra effects were antagonized by application of NO scavengers, consistent with the postulate that NO and cGMP are linked in the signaling pathway. To identify other components of the signaling system we analyzed gene expression changes induced by Viagra treatment using microarrays and quantitative real-time reverse transcription-polymerase chain reaction. Preliminary microarray analysis revealed several genes whose expression was significantly altered by Viagra treatment. Three of these genes had strong sequence similarity to key signal transduction or stress response genes and quantitative real-time reverse transcription-polymerase chain reaction was used to more rigorously quantify the effects of Viagra on their expression in spores and to test how closely these effects could be mimicked by treatment with dibutyryl cGMP. Taken together our results implicate NO and cGMP as downstream effectors that help link the gravity stimulus to polarized growth in C. richardii spores. Sequence data from this article can be found in the GenBank/EMBL data libraries under accession numbers BE 640669 to BE 643506, BQ 086920 to BQ 087668, and CV 734654 to CV 736151.
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Affiliation(s)
- Mari L Salmi
- Section of Molecular Cell and Developmental Biology, University of Texas, Austin, TX 78712, USA
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Bushart TJ, Roux SJ. Conserved features of germination and polarized cell growth: a few insights from a pollen-fern spore comparison. Ann Bot 2007; 99:9-17. [PMID: 16867999 PMCID: PMC2802967 DOI: 10.1093/aob/mcl159] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2006] [Accepted: 06/12/2006] [Indexed: 05/11/2023]
Abstract
BACKGROUND The germination of both pollen and fern spores results in the emergence of a cell-pollen tube from pollen, rhizoid from spore-that grows in a polar fashion, primarily at its apical end. In both of these tip-growing cells, the delivery of secretory vesicles to the growing end is guided in part by a calcium gradient, with calcium entering at the tip where it is most highly concentrated. The similarities between the two systems extend beyond tip-focused calcium gradients to encompass signalling pathways and elements including calmodulin, nitric oxide, annexins and Rop-GTPases. SCOPE AND AIMS This review is limited to those pathways and elements that function similarly in fern and pollen systems based on currently available evidence. The aim is to illustrate the common mechanisms by which tip growth occurs, facilitate further investigations into this area, and examine the implications for the evolutionarily conserved control of tip growth. CONCLUSIONS The interplay of calcium, nitric oxide and other effectors in both pollen and fern spores suggests certain signalling pathways became important regulators of germination and growth early in the evolution of land plants. Both large- and small-scale comparative genomic methods have shown to be promising in their ability to find new and relevant comparisons for further research. Cross-species comparisons may serve to speed up this process by highlighting both basic pathways and system-specific deviations.
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Affiliation(s)
| | - Stanley J. Roux
- Molecular Cell and Developmental Biology, University of Texas, Austin, TX 78751, USA
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Jeter CR, Roux SJ. Plant responses to extracellular nucleotides: Cellular processes and biological effects. Purinergic Signal 2006; 2:443-9. [PMID: 18404482 PMCID: PMC2254475 DOI: 10.1007/s11302-005-3981-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2005] [Accepted: 08/26/2005] [Indexed: 11/26/2022] Open
Abstract
Higher plants exhibit cellular responsiveness to the exogenous application of purine nucleotides in a manner consistent with a cell–cell signaling function for these molecules. Like animals, plants respond to extracellular ATP, ADP, and stable analogues (e.g., ATPγS and ADPβS) by increasing the cytoplasmic concentration of calcium. Agonist substrate specificity and concentration dependency suggest receptor mediation of these events, and, although the identity of the plant receptor is currently unknown, pharmacological analysis points to the involvement of a plasma membrane-localized calcium channel. Extracellular ATP can also induce the production of reactive oxygen species and stimulate an increase in the mRNA levels of a number of stress- and calcium-regulated genes, suggesting a role for nucleotide-based signaling in plant wound and defense responses. Furthermore, the growth and development of plants can also be altered by the application of external ATP. Recent studies are only beginning to uncover the complexities of plant signaling networks activated in response to extracellular ATP and how these might interact to affect plant physiological processes.
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Affiliation(s)
- Collene R. Jeter
- Science Park-Research Division, Department of Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville, TX 78957 USA
| | - Stanley J. Roux
- Section of Molecular Cell and Developmental Biology, The University of Texas-Austin, University Station A6700, Austin, TX 78712-0183 USA
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Haque AU, Rokkam M, Carlo ARD, Wereley ST, Wells HW, McLamb WT, Roux SJ, Irazoqui PP, Porterfield DM. Design, Fabrication and Characterization of anIn SilicoCell Physiology lab for Bio Sensing Applications. ACTA ACUST UNITED AC 2006. [DOI: 10.1088/1742-6596/34/1/122] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Song CJ, Steinebrunner I, Wang X, Stout SC, Roux SJ. Extracellular ATP induces the accumulation of superoxide via NADPH oxidases in Arabidopsis. Plant Physiol 2006; 140:1222-32. [PMID: 16428598 PMCID: PMC1435826 DOI: 10.1104/pp.105.073072] [Citation(s) in RCA: 210] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Extracellular ATP can serve as a signaling agent in animal cells, and, as suggested by recent reports, may also do so in plant cells. In animal cells it induces the production of reactive oxygen species through the mediation of NADPH oxidase. Similarly, here we report that in leaves of Arabidopsis (Arabidopsis thaliana), applied ATP, but not AMP or phosphate, induces the accumulation of superoxide (O2-) in a biphasic, dose-dependent manner, with a threshold at 500 nm ATP. This effect did not require ATP hydrolysis for it was mimicked by ATPgammaS. ATP also induced increased levels of Arabidopsis respiratory burst oxidase homolog D (AtrbohD) mRNA, but ATP-treated plants that had disrupted AtrbohD and AtrbohF genes did not accumulate O2-, indicating that NADPH oxidases are responsible for the induced O2- accumulation. Inhibitors of mammalian P2-type ATP receptors abolished ATP-induced O2- production, suggesting that the ATP effects may be mediated through P2-like receptors in plants. Cytosolic Ca2+ and calmodulin are likely to help transduce the ATP responses, as they do in animal cells, because a Ca2+ channel blocker, a Ca2+ chelator, and calmodulin antagonist all reduced ATP-induced O2- accumulation. Furthermore, ATP treatment enhanced the expression of genes that are induced by wounds and other stresses. The ATP measured at wound sites averaged 40 microm, well above the level needed to induce O2- accumulation and gene expression changes. Transgenic plants overexpressing an apyrase gene had reduced O2- production in response to applied ATP and wounding. Together, these data suggest a possible role for extracellular ATP as a signal potentially in wound and stress responses.
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Affiliation(s)
- Charlotte J Song
- Section of Molecular Cell and Developmental Biology, University of Texas, Austin, Texas 78712, USA
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