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Xie H, Ye X, Liu C, Li D, Wang X, Xu C, Li C, Luo K, Fan D, Wu N. The microRNA7833-AUX6 module plays a critical role in wood development by modulating cellular auxin influx in Populus tomentosa. TREE PHYSIOLOGY 2024; 44:tpad153. [PMID: 38113530 DOI: 10.1093/treephys/tpad153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 12/12/2023] [Indexed: 12/21/2023]
Abstract
The critical role of auxin on secondary vascular development in woody plants has been demonstrated. The concentration gradient of endogenous indole-3-acetic acid and the cellular and molecular pathways contributing to the auxin-directed vascular organization and wood growth have been uncovered in recent decades. However, our understanding of the roles and regulations of auxin influx in wood formation in trees remains limited. Here, we reported that a microRNA, miR7833, participates in the negative regulation of stem cambial cell division and secondary xylem development in Populus tomentosa. The miR7833 is mainly expressed in the vascular cambium during stem radical growth and specifically targets and represses two AUX/LAX family auxin influx carriers, AUX5 and AUX6, in poplar. We further revealed that poplar AUX6, the most abundant miR7833 target in the stem, is preferentially enriched in the developing xylem and is a positive regulator for cell division and differentiation events during wood formation. Moreover, inhibition of auxin influx carriers by 1-naphthoxyacetic acids abolished the regulatory effects of miR7833 and AUX6 on secondary xylem formation in poplar. Our results revealed the essential roles of the miR7833-AUX6 module in regulating cellular events in secondary xylem development and demonstrated an auxin influx-dependent mechanism for wood formation in poplar.
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Affiliation(s)
- Haiyan Xie
- Chongqing Key Laboratory of Plant Resource Conservation and Germplasm Innovation, Integrative Science Center of Germplasm Creation in Western China (Chongqing) Science City, Key Laboratory of Eco-Environments of Three Gorges Reservoir Region, Ministry of Education, Institute of Resources Botany, School of Life Sciences, Southwest University, Chongqing 400715, China
| | - Xiao Ye
- Chongqing Key Laboratory of Plant Resource Conservation and Germplasm Innovation, Integrative Science Center of Germplasm Creation in Western China (Chongqing) Science City, Key Laboratory of Eco-Environments of Three Gorges Reservoir Region, Ministry of Education, Institute of Resources Botany, School of Life Sciences, Southwest University, Chongqing 400715, China
| | - Chang Liu
- Chongqing Key Laboratory of Plant Resource Conservation and Germplasm Innovation, Integrative Science Center of Germplasm Creation in Western China (Chongqing) Science City, Key Laboratory of Eco-Environments of Three Gorges Reservoir Region, Ministry of Education, Institute of Resources Botany, School of Life Sciences, Southwest University, Chongqing 400715, China
| | - Dan Li
- Chongqing Key Laboratory of Plant Resource Conservation and Germplasm Innovation, Integrative Science Center of Germplasm Creation in Western China (Chongqing) Science City, Key Laboratory of Eco-Environments of Three Gorges Reservoir Region, Ministry of Education, Institute of Resources Botany, School of Life Sciences, Southwest University, Chongqing 400715, China
| | - Xianqiang Wang
- Chongqing Key Laboratory of Plant Resource Conservation and Germplasm Innovation, Integrative Science Center of Germplasm Creation in Western China (Chongqing) Science City, Key Laboratory of Eco-Environments of Three Gorges Reservoir Region, Ministry of Education, Institute of Resources Botany, School of Life Sciences, Southwest University, Chongqing 400715, China
| | - Changzheng Xu
- Chongqing Key Laboratory of Plant Resource Conservation and Germplasm Innovation, Integrative Science Center of Germplasm Creation in Western China (Chongqing) Science City, Key Laboratory of Eco-Environments of Three Gorges Reservoir Region, Ministry of Education, Institute of Resources Botany, School of Life Sciences, Southwest University, Chongqing 400715, China
| | - Caofeng Li
- Chongqing Key Laboratory of Plant Resource Conservation and Germplasm Innovation, Integrative Science Center of Germplasm Creation in Western China (Chongqing) Science City, Key Laboratory of Eco-Environments of Three Gorges Reservoir Region, Ministry of Education, Institute of Resources Botany, School of Life Sciences, Southwest University, Chongqing 400715, China
| | - Keming Luo
- Chongqing Key Laboratory of Plant Resource Conservation and Germplasm Innovation, Integrative Science Center of Germplasm Creation in Western China (Chongqing) Science City, Key Laboratory of Eco-Environments of Three Gorges Reservoir Region, Ministry of Education, Institute of Resources Botany, School of Life Sciences, Southwest University, Chongqing 400715, China
| | - Di Fan
- Chongqing Key Laboratory of Plant Resource Conservation and Germplasm Innovation, Integrative Science Center of Germplasm Creation in Western China (Chongqing) Science City, Key Laboratory of Eco-Environments of Three Gorges Reservoir Region, Ministry of Education, Institute of Resources Botany, School of Life Sciences, Southwest University, Chongqing 400715, China
| | - Nengbiao Wu
- Chongqing Key Laboratory of Plant Resource Conservation and Germplasm Innovation, Integrative Science Center of Germplasm Creation in Western China (Chongqing) Science City, Key Laboratory of Eco-Environments of Three Gorges Reservoir Region, Ministry of Education, Institute of Resources Botany, School of Life Sciences, Southwest University, Chongqing 400715, China
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Tan C, Li S, Song J, Zheng X, Zheng H, Xu W, Wan C, Zhang T, Bian Q, Men S. 3,4-Dichlorophenylacetic acid acts as an auxin analog and induces beneficial effects in various crops. Commun Biol 2024; 7:161. [PMID: 38332111 PMCID: PMC10853179 DOI: 10.1038/s42003-024-05848-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 01/23/2024] [Indexed: 02/10/2024] Open
Abstract
Auxins and their analogs are widely used to promote root growth, flower and fruit development, and yield in crops. The action characteristics and application scope of various auxins are different. To overcome the limitations of existing auxins, expand the scope of applications, and reduce side effects, it is necessary to screen new auxin analogs. Here, we identified 3,4-dichlorophenylacetic acid (Dcaa) as having auxin-like activity and acting through the auxin signaling pathway in plants. At the physiological level, Dcaa promotes the elongation of oat coleoptile segments, the generation of adventitious roots, and the growth of crop roots. At the molecular level, Dcaa induces the expression of auxin-responsive genes and acts through auxin receptors. Molecular docking results showed that Dcaa can bind to auxin receptors, among which TIR1 has the highest binding activity. Application of Dcaa at the root tip of the DR5:GUS auxin-responsive reporter induces GUS expression in the root hair zone, which requires the PIN2 auxin efflux carrier. Dcaa also inhibits the endocytosis of PIN proteins like other auxins. These results provide a basis for the application of Dcaa in agricultural practices.
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Affiliation(s)
- Chao Tan
- Tianjin Key Laboratory of Protein Sciences, Department of Plant Biology and Ecology, College of Life Sciences, Nankai University, 300071, Tianjin, China
| | - Suxin Li
- Tianjin Key Laboratory of Protein Sciences, Department of Plant Biology and Ecology, College of Life Sciences, Nankai University, 300071, Tianjin, China
| | - Jia Song
- Tianjin Key Laboratory of Protein Sciences, Department of Plant Biology and Ecology, College of Life Sciences, Nankai University, 300071, Tianjin, China
| | - Xianfu Zheng
- Zhengzhou ZhengShi Chemical Co., Ltd, 450000, Zhengzhou, China
| | - Hao Zheng
- Zhengzhou ZhengShi Chemical Co., Ltd, 450000, Zhengzhou, China
| | - Weichang Xu
- Zhengzhou ZhengShi Chemical Co., Ltd, 450000, Zhengzhou, China
| | - Cui Wan
- Zhengzhou ZhengShi Chemical Co., Ltd, 450000, Zhengzhou, China
| | - Tan Zhang
- Tianjin Key Laboratory of Protein Sciences, Department of Plant Biology and Ecology, College of Life Sciences, Nankai University, 300071, Tianjin, China
| | - Qiang Bian
- National Pesticide Engineering Research Center (Tianjin), College of Chemistry, Nankai University, 300071, Tianjin, China.
| | - Shuzhen Men
- Tianjin Key Laboratory of Protein Sciences, Department of Plant Biology and Ecology, College of Life Sciences, Nankai University, 300071, Tianjin, China.
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3
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Wiśniewska J, Kęsy J, Mucha N, Tyburski J. Auxin resistant 1 gene (AUX1) mediates auxin effect on Arabidopsis thaliana callus growth by regulating its content and distribution pattern. JOURNAL OF PLANT PHYSIOLOGY 2024; 293:154168. [PMID: 38176282 DOI: 10.1016/j.jplph.2023.154168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2023] [Revised: 12/28/2023] [Accepted: 12/29/2023] [Indexed: 01/06/2024]
Abstract
Callus sustained growth relies heavily on auxin, which is supplied to the culture medium. Surprisingly, there is a noticeable absence of information regarding the involvement of carrier-mediated auxin polar transport gene in callus growth regulation. Here, we delve into the role of the AUXIN RESISTANT 1 (AUX1) influx transporter in the regulation of callus growth, comparing the effects under conditions of light versus darkness. It was observed that callus growth was significantly enhanced under light illumination. This growth-stimulatory effect was accompanied by a decrease in the levels of free auxin within the callus cells when compared to conditions of darkness. In the aux1-22 mutant callus, which lacks functional AUX1, there was a substantial reduction in IAA levels. Nonetheless, the mutant callus exhibited markedly higher growth rates compared to the wild type. This suggests that the reduction in exogenous auxin uptake through the AUX1-dependent pathway may prevent the overaccumulation of growth-restricting hormone concentrations. The growth-stimulatory effect of AUX1 deficiency was counteracted by nonspecific auxin influx transport inhibitors. This finding shows that other auxin influx carriers likely play a role in facilitating the diffusion of auxin from the culture medium to sustain high growth rates. AUX1 was primarily localized in the plasma membranes of the two outermost cell layers of the callus clump and the parenchyma cells adjacent to tracheary elements. Significantly, these locations coincided with the regions of maximal auxin concentration. Consequently, it can be inferred that AUX1 mediates the auxin distribution within the callus.
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Affiliation(s)
- Justyna Wiśniewska
- Plant Physiology and Biotechnology Department, Nicolaus Copernicus University in Toruń, Lwowska 1, 87-100 Toruń, Poland; Centre for Modern Interdisciplinary Technologies, Nicolaus Copernicus University in Toruń, Wileńska 4, 87-100 Toruń, Poland
| | - Jacek Kęsy
- Plant Physiology and Biotechnology Department, Nicolaus Copernicus University in Toruń, Lwowska 1, 87-100 Toruń, Poland
| | - Natalia Mucha
- Plant Physiology and Biotechnology Department, Nicolaus Copernicus University in Toruń, Lwowska 1, 87-100 Toruń, Poland
| | - Jarosław Tyburski
- Plant Physiology and Biotechnology Department, Nicolaus Copernicus University in Toruń, Lwowska 1, 87-100 Toruń, Poland; Centre for Modern Interdisciplinary Technologies, Nicolaus Copernicus University in Toruń, Wileńska 4, 87-100 Toruń, Poland.
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Jobert F, Soriano A, Brottier L, Casset C, Divol F, Safran J, Lefebvre V, Pelloux J, Robert S, Péret B. Auxin triggers pectin modification during rootlet emergence in white lupin. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2022; 112:1127-1140. [PMID: 36178138 DOI: 10.1111/tpj.15993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 09/23/2022] [Accepted: 09/25/2022] [Indexed: 06/16/2023]
Abstract
Emergence of secondary roots through parental tissue is a highly controlled developmental process. Although the model plant Arabidopsis has been useful to uncover the predominant role of auxin in this process, its simple root structure is not representative of how emergence takes place in most plants, which display more complex root anatomy. White lupin is a legume crop producing structures called cluster roots, where closely spaced rootlets emerge synchronously. Rootlet primordia push their way through several cortical cell layers while maintaining the parent root integrity, reflecting more generally the lateral root emergence process in most multilayered species. In this study, we showed that lupin rootlet emergence is associated with an upregulation of cell wall pectin modifying and degrading genes under the active control of auxin. Among them, we identified LaPG3, a polygalacturonase gene typically expressed in cells surrounding the rootlet primordium and we showed that its downregulation delays emergence. Immunolabeling of pectin epitopes and their quantification uncovered a gradual pectin demethylesterification in the emergence zone, which was further enhanced by auxin treatment, revealing a direct hormonal control of cell wall properties. We also report rhamnogalacturonan-I modifications affecting cortical cells that undergo separation as a consequence of primordium outgrowth. In conclusion, we describe a model of how external tissues in front of rootlet primordia display cell wall modifications to allow for the passage of newly formed rootlets.
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Affiliation(s)
- François Jobert
- IPSiM, Univ Montpellier, CNRS, INRAE, Supagro, 34060, Montpellier, France
- Umeå Plant Science Centre (UPSC), Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 901 83, Umeå, Sweden
| | - Alexandre Soriano
- IPSiM, Univ Montpellier, CNRS, INRAE, Supagro, 34060, Montpellier, France
| | - Laurent Brottier
- IPSiM, Univ Montpellier, CNRS, INRAE, Supagro, 34060, Montpellier, France
| | - Célia Casset
- IPSiM, Univ Montpellier, CNRS, INRAE, Supagro, 34060, Montpellier, France
| | - Fanchon Divol
- IPSiM, Univ Montpellier, CNRS, INRAE, Supagro, 34060, Montpellier, France
| | - Josip Safran
- UMR INRAE 1158 BioEcoAgro, BIOPI Biologie des Plantes et Innovation, SFR Condorcet FR CNRS 3417, Université de Picardie, 80039, Amiens, France
| | - Valérie Lefebvre
- UMR INRAE 1158 BioEcoAgro, BIOPI Biologie des Plantes et Innovation, SFR Condorcet FR CNRS 3417, Université de Picardie, 80039, Amiens, France
| | - Jérôme Pelloux
- UMR INRAE 1158 BioEcoAgro, BIOPI Biologie des Plantes et Innovation, SFR Condorcet FR CNRS 3417, Université de Picardie, 80039, Amiens, France
| | - Stéphanie Robert
- Umeå Plant Science Centre (UPSC), Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 901 83, Umeå, Sweden
| | - Benjamin Péret
- IPSiM, Univ Montpellier, CNRS, INRAE, Supagro, 34060, Montpellier, France
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5
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Aizezi Y, Xie Y, Guo H, Jiang K. New Wine in an Old Bottle: Utilizing Chemical Genetics to Dissect Apical Hook Development. LIFE (BASEL, SWITZERLAND) 2022; 12:life12081285. [PMID: 36013464 PMCID: PMC9410295 DOI: 10.3390/life12081285] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 08/12/2022] [Accepted: 08/17/2022] [Indexed: 02/08/2023]
Abstract
The apical hook is formed by dicot seedlings to protect the tender shoot apical meristem during soil emergence. Regulated by many phytohormones, the apical hook has been taken as a model to study the crosstalk between individual signaling pathways. Over recent decades, the roles of different phytohormones and environmental signals in apical hook development have been illustrated. However, key regulators downstream of canonical hormone signaling have rarely been identified via classical genetics screening, possibly due to genetic redundancy and/or lethal mutation. Chemical genetics that utilize small molecules to perturb and elucidate biological processes could provide a complementary strategy to overcome the limitations in classical genetics. In this review, we summarize current progress in hormonal regulation of the apical hook, and previously reported chemical tools that could assist the understanding of this complex developmental process. We also provide insight into novel strategies for chemical screening and target identification, which could possibly lead to discoveries of new regulatory components in apical hook development, or unidentified signaling crosstalk that is overlooked by classical genetics screening.
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Affiliation(s)
- Yalikunjiang Aizezi
- Institute of Plant and Food Science, Department of Biology, School of Life Sciences, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
- Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Southern University of Science and Technology, Shenzhen 518055, China
| | - Yinpeng Xie
- Institute of Plant and Food Science, Department of Biology, School of Life Sciences, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
- Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Southern University of Science and Technology, Shenzhen 518055, China
| | - Hongwei Guo
- Institute of Plant and Food Science, Department of Biology, School of Life Sciences, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
- Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Southern University of Science and Technology, Shenzhen 518055, China
- Correspondence: (H.G.); (K.J.)
| | - Kai Jiang
- Institute of Plant and Food Science, Department of Biology, School of Life Sciences, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
- Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Southern University of Science and Technology, Shenzhen 518055, China
- Correspondence: (H.G.); (K.J.)
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6
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Balcerowicz M, Shetty KN, Jones AM. Fluorescent biosensors illuminating plant hormone research. PLANT PHYSIOLOGY 2021; 187:590-602. [PMID: 35237816 PMCID: PMC8491072 DOI: 10.1093/plphys/kiab278] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 05/22/2021] [Indexed: 05/20/2023]
Abstract
Phytohormones act as key regulators of plant growth that coordinate developmental and physiological processes across cells, tissues and organs. As such, their levels and distribution are highly dynamic owing to changes in their biosynthesis, transport, modification and degradation that occur over space and time. Fluorescent biosensors represent ideal tools to track these dynamics with high spatiotemporal resolution in a minimally invasive manner. Substantial progress has been made in generating a diverse set of hormone sensors with recent FRET biosensors for visualising hormone concentrations complementing information provided by transcriptional, translational and degron-based reporters. In this review, we provide an update on fluorescent biosensor designs, examine the key properties that constitute an ideal hormone biosensor, discuss the use of these sensors in conjunction with in vivo hormone perturbations and highlight the latest discoveries made using these tools.
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Affiliation(s)
| | | | - Alexander M. Jones
- Sainsbury Laboratory, Cambridge University, Cambridge CB2 1LR, UK
- Author for communication:
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Alaguero-Cordovilla A, Sánchez-García AB, Ibáñez S, Albacete A, Cano A, Acosta M, Pérez-Pérez JM. An auxin-mediated regulatory framework for wound-induced adventitious root formation in tomato shoot explants. PLANT, CELL & ENVIRONMENT 2021; 44:1642-1662. [PMID: 33464573 DOI: 10.1111/pce.14001] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 12/30/2020] [Accepted: 01/04/2021] [Indexed: 05/24/2023]
Abstract
Adventitious roots (ARs) are produced from non-root tissues in response to different environmental signals, such as abiotic stresses, or after wounding, in a complex developmental process that requires hormonal crosstalk. Here, we characterized AR formation in young seedlings of Solanum lycopersicum cv. 'Micro-Tom' after whole root excision by means of physiological, genetic and molecular approaches. We found that a regulated basipetal auxin transport from the shoot and local auxin biosynthesis triggered by wounding are both required for the re-establishment of internal auxin gradients within the vasculature. This promotes cell proliferation at the distal cambium near the wound in well-defined positions of the basal hypocotyl and during a narrow developmental window. In addition, a pre-established pattern of differential auxin responses along the apical-basal axis of the hypocotyl and an as of yet unknown cell-autonomous inhibitory pathway contribute to the temporal and spatial patterning of the newly formed ARs on isolated hypocotyl explants. Our work provides an experimental outline for the dissection of wound-induced AR formation in tomato, a species that is suitable for molecular identification of gene regulatory networks via forward and reverse genetics approaches.
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Affiliation(s)
| | | | - Sergio Ibáñez
- Instituto de Bioingeniería, Universidad Miguel Hernández, Elche, Spain
| | - Alfonso Albacete
- Present address: Instituto Murciano de Investigación y Desarrollo Agrario y Alimentario (IMIDA), La Alberca, Spain
- CEBAS-CSIC, Department of Plant Nutrition, Campus Universitario de Espinardo, Espinardo, Murcia, Spain
| | - Antonio Cano
- Departamento de Biología Vegetal, Universidad de Murcia, Murcia, Spain
| | - Manuel Acosta
- Departamento de Biología Vegetal, Universidad de Murcia, Murcia, Spain
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Jahn L, Hofmann U, Ludwig-Müller J. Indole-3-Acetic Acid Is Synthesized by the Endophyte Cyanodermella asteris via a Tryptophan-Dependent and -Independent Way and Mediates the Interaction with a Non-Host Plant. Int J Mol Sci 2021; 22:2651. [PMID: 33800748 PMCID: PMC7961953 DOI: 10.3390/ijms22052651] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 02/26/2021] [Accepted: 03/02/2021] [Indexed: 11/17/2022] Open
Abstract
The plant hormone indole-3-acetic acid (IAA) is one of the main signals playing a role in the communication between host and endophytes. Endophytes can synthesize IAA de novo to influence the IAA homeostasis in plants. Although much is known about IAA biosynthesis in microorganisms, there is still less known about the pathway by which IAA is synthesized in fungal endophytes. The aim of this study is to examine a possible IAA biosynthesis pathway in Cyanodermella asteris. In vitro cultures of C. asteris were incubated with the IAA precursors tryptophan (Trp) and indole, as well as possible intermediates, and they were additionally treated with IAA biosynthesis inhibitors (2-mercaptobenzimidazole and yucasin DF) to elucidate possible IAA biosynthesis pathways. It was shown that (a) C. asteris synthesized IAA without adding precursors; (b) indole-3-acetonitrile (IAN), indole-3-acetamide (IAM), and indole-3-acetaldehyde (IAD) increased IAA biosynthesis; and (c) C. asteris synthesized IAA also by a Trp-independent pathway. Together with the genome information of C. asteris, the possible IAA biosynthesis pathways found can improve the understanding of IAA biosynthesis in fungal endophytes. The uptake of fungal IAA into Arabidopsis thaliana is necessary for the induction of lateral roots and other fungus-related growth phenotypes, since the application of the influx inhibitor 2-naphthoxyacetic acid (NOA) but not the efflux inhibitor N-1-naphtylphthalamic acid (NPA) were altering these parameters. In addition, the root phenotype of the mutation in an influx carrier, aux1, was partially rescued by C. asteris.
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Affiliation(s)
| | | | - Jutta Ludwig-Müller
- Institute of Botany, Faculty of Biology, Technische Universität Dresden, 01062 Dresden, Germany; (L.J.); (U.H.)
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Li YH, Mo YW, Wang SB, Zhang Z. Auxin efflux carriers, MiPINs, are involved in adventitious root formation of mango cotyledon segments. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2020; 150:15-26. [PMID: 32105796 DOI: 10.1016/j.plaphy.2020.02.028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 01/27/2020] [Accepted: 02/19/2020] [Indexed: 05/12/2023]
Abstract
Adventitious roots form only at the proximal cut surface (PCS) but not at the distal cut surface (DCS) of mango cotyledon segments. In this study, mango embryos treated with indole-3-butyric acid (IBA) showed significantly increased adventitious root formation, while those treated with 2, 3, 5-triiodobenzoic acid (TIBA) demonstrated complete inhibition of adventitious rooting. Mango embryos treated with auxin influx inhibitors demonstrated lower inhibition of adventitious roots than those treated with TIBA. The endogenous indol-3-acetic acid (IAA) content on the PCS and DCS was similar at 0 h, then increased on both surfaces after 6 h, and IAA content on the PCS were always higher than those on the DCS. We cloned three genes encoding auxin efflux carriers (i.e., MiPIN2-4) and examined their temporal and spatial expression patterns under different treatments. Relative expression of all MiPINs studied was very low at 0 h but significantly increased on both PCS and DCS from 1 d to 10 d, to varying degrees. We overexpressed MiPIN1-4 in Arabidopsis plants and found a significant increase in adventitious root quantity in MiPIN1 and MiPIN3 transgenic lines. Immunofluorescence results showed that MiPIN1 and MiPIN3 are primarily localized in the vascular tissues and the cells adjacent to abaxial surface. In conclusion, we propose that in mango cotyledon segments, wounding stimulates IAA biosynthesis, the transcription levels of PIN genes were significantly increased in different magnitudes on the PCS and DCS, resulting in polar IAA transport from the DCS to PCS via the vascular tissues, thereby triggering adventitious root formation.
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Affiliation(s)
- Yun-He Li
- Key Laboratory of Tropical Fruit Biology, Ministry of Agriculture, South Subtropical Crop Research Institute, Chinese Academy of Tropical Agricultural Sciences, Zhanjiang, 524091, China.
| | - Yi-Wei Mo
- College of Life Science, Shaoxing University, Shaoxing, 312000, China
| | - Song-Biao Wang
- Key Laboratory of Tropical Fruit Biology, Ministry of Agriculture, South Subtropical Crop Research Institute, Chinese Academy of Tropical Agricultural Sciences, Zhanjiang, 524091, China
| | - Zhi Zhang
- Key Laboratory of Tropical Fruit Biology, Ministry of Agriculture, South Subtropical Crop Research Institute, Chinese Academy of Tropical Agricultural Sciences, Zhanjiang, 524091, China
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10
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Asfaw KG, Liu Q, Maisch J, Münch SW, Wehl I, Bräse S, Bogeski I, Schepers U, Nick P. A Peptoid Delivers CoQ-derivative to Plant Mitochondria via Endocytosis. Sci Rep 2019; 9:9839. [PMID: 31285457 PMCID: PMC6614412 DOI: 10.1038/s41598-019-46182-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Accepted: 06/21/2019] [Indexed: 11/09/2022] Open
Abstract
Controlled delivery of molecules interfering specifically with target activities in a cell of interest can be a powerful tool for experimental manipulation, because it can be administered at a defined time point and does not require genetic transformation, which in some systems is difficult and time consuming. Peptides as versatile tools that can be tailored for binding numerous binding partners, are of special interest. However, their passage through membranes, their intracellular targeting, and their sensitivity to proteases is limiting. The use of peptoids, where cationic amino-acid side chains are linked to nitrogen (rather than to carbon) of the peptide bond, can circumvent these limitations, because they are not cleavable by proteases. In the current work, we provide a proof-of-concept that such Trojan Peptoids, the plant PeptoQ, can be used to target a functional cargo (i.e. a rhodamine-labelled peptoid and a coenzyme Q10 derivative) into mitochondria of tobacco BY-2 cells as experimental model. We show that the uptake is specific for mitochondria, rapid, dose-dependent, and requires clathrin-mediated endocytosis, as well as actin filaments, while microtubules seem to be dispensable. Viability of the treated cells is not affected, and they show better survival under salt stress, a condition that perturbs oxidative homeostasis in mitochondria. In congruence with improved homeostasis, we observe that the salt induced accumulation of superoxide is mitigated and even inverted by pretreatment with PeptoQ. Using double labelling with appropriate fluorescent markers, we show that targeting of this Trojan Peptoid to the mitochondria is not based on a passage through the plasma membrane (as thought hitherto), but on import via endocytotic vesicles and subsequent accumulation in the mitochondrial intermembrane space, from where it can enter the matrix, e.g. when the permeability of the inner membrane is increased under salt stress.
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Affiliation(s)
- Kinfemichael Geressu Asfaw
- Molecular Cell Biology, Botanical Institute, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 4, D-76131, Karlsruhe, Germany.
| | - Qiong Liu
- Molecular Cell Biology, Botanical Institute, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 4, D-76131, Karlsruhe, Germany
| | - Jan Maisch
- Molecular Cell Biology, Botanical Institute, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 4, D-76131, Karlsruhe, Germany
| | - Stephan W Münch
- Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, D-76131, Karlsruhe, Germany
| | - Ilona Wehl
- Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, D-76131, Karlsruhe, Germany
- Institute of Toxicology and Genetics (ITG), Karlsruhe Institute of Technology (KIT), Hermann von Helmholtz Platz 1 D-76344, Eggenstein-Leopoldshafen, Germany
| | - Stefan Bräse
- Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, D-76131, Karlsruhe, Germany
- Institute of Toxicology and Genetics (ITG), Karlsruhe Institute of Technology (KIT), Hermann von Helmholtz Platz 1 D-76344, Eggenstein-Leopoldshafen, Germany
| | - Ivan Bogeski
- Molecular Physiology, Institute of Cardiovascular Physiology, University Medical Center, Georg-August-University, 37073, Göttingen, Germany
| | - Ute Schepers
- Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, D-76131, Karlsruhe, Germany
- Institute of Functional Interfaces (IFG), Karlsruhe Institute of Technology (KIT), Hermann von Helmholtz Platz 1, 76344, Eggenstein-Leopoldshafen, Germany
| | - Peter Nick
- Molecular Cell Biology, Botanical Institute, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 4, D-76131, Karlsruhe, Germany
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11
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Ilina EL, Kiryushkin AS, Semenova VA, Demchenko NP, Pawlowski K, Demchenko KN. Lateral root initiation and formation within the parental root meristem of Cucurbita pepo: is auxin a key player? ANNALS OF BOTANY 2018; 122:873-888. [PMID: 29684107 PMCID: PMC6215038 DOI: 10.1093/aob/mcy052] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 03/20/2018] [Indexed: 05/24/2023]
Abstract
Background and Aims In some plant families, including Cucurbitaceae, initiation and development of lateral roots (LRs) occur in the parental root apical meristem. The objective of this study was to identify the general mechanisms underlying LR initiation (LRI). Therefore, the first cellular events leading to LRI as well as the role of auxin in this process were studied in the Cucurbita pepo root apical meristem. Methods Transgenic hairy roots harbouring the auxin-responsive promoter DR5 fused to different reporter genes were used for visualizing of cellular auxin response maxima (ARMs) via confocal laser scanning microscopy and 3-D imaging. The effects of exogenous auxin and auxin transport inhibitors on root branching were analysed. Key Results The earliest LRI event involved a group of symmetric anticlinal divisions in pericycle cell files at a distance of 250-350 µm from the initial cells. The visualization of the ARMs enabled the precise detection of cells involved in determining the site of LR primordium formation. A local ARM appeared in sister cells of the pericycle and endodermis files before the first division. Cortical cells contributed to LR development after the anticlinal divisions in the pericycle via the formation of an ARM. Exogenous auxins did not increase the total number of LRs and did not affect the LRI index. Although exogenous auxin transport inhibitors acted in different ways, they all reduced the number of LRs formed. Conclusions Literature data, as well as results obtained in this study, suggest that the formation of a local ARM before the first anticlinal formative divisions is the common mechanism underlying LRI in flowering plants. We propose that the mechanisms of the regulation of root branching are independent of the position of the LRI site relative to the parental root tip.
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Affiliation(s)
- Elena L Ilina
- Laboratory of Cellular and Molecular Mechanisms of Plant Development, Komarov Botanical Institute, Russian Academy of Sciences, Saint-Petersburg, Russia
| | - Alexey S Kiryushkin
- Laboratory of Cellular and Molecular Mechanisms of Plant Development, Komarov Botanical Institute, Russian Academy of Sciences, Saint-Petersburg, Russia
| | - Victoria A Semenova
- Laboratory of Cellular and Molecular Mechanisms of Plant Development, Komarov Botanical Institute, Russian Academy of Sciences, Saint-Petersburg, Russia
| | - Nikolay P Demchenko
- Laboratory of Cellular and Molecular Mechanisms of Plant Development, Komarov Botanical Institute, Russian Academy of Sciences, Saint-Petersburg, Russia
| | - Katharina Pawlowski
- Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden
| | - Kirill N Demchenko
- Laboratory of Cellular and Molecular Mechanisms of Plant Development, Komarov Botanical Institute, Russian Academy of Sciences, Saint-Petersburg, Russia
- Laboratory of Molecular and Cellular Biology, All-Russia Research Institute for Agricultural Microbiology, Podbelsky chaussee, Saint-Petersburg, Russia
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12
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Advances in Understanding the Mechanism of Action of the Auxin Permease AUX1. Int J Mol Sci 2018; 19:ijms19113391. [PMID: 30380696 PMCID: PMC6275028 DOI: 10.3390/ijms19113391] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 10/19/2018] [Accepted: 10/24/2018] [Indexed: 01/08/2023] Open
Abstract
In over 40 years of research on the cellular uptake of auxin it is somewhat chastening that we have elaborated so little on the original kinetic descriptions of auxin uptake by plant cells made by Rubery and Sheldrake in 1974. Every aspect of that seminal work has been investigated in detail, and the uptake activity they measured is now known to be attributed to the AUX1/LAX family of permeases. Recent pharmacological studies have defined the substrate specificity of AUX1, biochemical studies have evaluated its permeability to auxin in plant cell membranes, and rigourous kinetic studies have confirmed the affinity of AUX1 for IAA and synthetic auxins. Advances in genome sequencing have provided a rich resource for informatic analysis of the ancestry of AUX1 and the LAX proteins and, along with models of topology, suggest mechanistic links to families of eukaryotic proton co-transporters for which crystal structures have been presented. The insights gained from all the accumulated research reflect the brilliance of Rubery and Sheldrake’s early work, but recent biochemical analyses are starting to advance further our understanding of this vitally important family of auxin transport proteins.
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13
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Barbosa ICR, Hammes UZ, Schwechheimer C. Activation and Polarity Control of PIN-FORMED Auxin Transporters by Phosphorylation. TRENDS IN PLANT SCIENCE 2018; 23:523-538. [PMID: 29678589 DOI: 10.1016/j.tplants.2018.03.009] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/25/2017] [Revised: 03/11/2018] [Accepted: 03/14/2018] [Indexed: 05/09/2023]
Abstract
Auxin controls almost every aspect of plant development. Auxin is distributed within the plant by passive diffusion and active cell-to-cell transport. PIN-FORMED (PIN) auxin efflux transporters are polarly distributed in the plasma membranes of many cells, and knowledge about their distribution can predict auxin transport and explain auxin distribution patterns, even in complex tissues. Recent studies have revealed that phosphorylation is essential for PIN activation, suggesting that PIN phosphorylation needs to be taken into account in understanding auxin transport. These findings also ask for a re-examination of previously proposed mechanisms for phosphorylation-dependent PIN polarity control. We provide a comprehensive summary of the current knowledge on PIN regulation by phosphorylation, and discuss possible mechanisms of PIN polarity control in the context of recent findings.
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Affiliation(s)
- Inês C R Barbosa
- Department of Plant Molecular Biology, Biophore Building, Unil-Sorge, Université de Lausanne, 1015 Lausanne, Switzerland; These authors contributed equally to this review article and are listed in alphabetical order
| | - Ulrich Z Hammes
- Plant Systems Biology, Technical University Munich, Emil-Ramann-Strasse 8, 85354 Freising, Germany; These authors contributed equally to this review article and are listed in alphabetical order
| | - Claus Schwechheimer
- Plant Systems Biology, Technical University Munich, Emil-Ramann-Strasse 8, 85354 Freising, Germany; These authors contributed equally to this review article and are listed in alphabetical order.
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14
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Hoyerova K, Hosek P, Quareshy M, Li J, Klima P, Kubes M, Yemm AA, Neve P, Tripathi A, Bennett MJ, Napier RM. Auxin molecular field maps define AUX1 selectivity: many auxin herbicides are not substrates. THE NEW PHYTOLOGIST 2018; 217:1625-1639. [PMID: 29265374 DOI: 10.1111/nph.14950] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Accepted: 11/04/2017] [Indexed: 05/10/2023]
Abstract
Developmental responses to auxin are regulated by facilitated uptake and efflux, but detailed molecular understanding of the carrier proteins is incomplete. We have used pharmacological tools to explore the chemical space that defines substrate preferences for the auxin uptake carrier AUX1. Total and partial loss-of-function aux1 mutants were assessed against wild-type for dose-dependent resistance to a range of auxins and analogues. We then developed an auxin accumulation assay with associated mathematical modelling to enumerate accurate IC50 values for a small library of auxin analogues. The structure activity relationship data were analysed using molecular field analyses to create a pharmacophoric atlas of AUX1 substrates. The uptake carrier exhibits a very high level of selectivity towards small substrates including the natural indole-3-acetic acid, and the synthetic auxin 2,4-dichlorophenoxyacetic acid. No AUX1 activity was observed for herbicides based on benzoic acid (dicamba), pyridinyloxyacetic acid (triclopyr) or the 6-arylpicolinates (halauxifen), and very low affinity was found for picolinic acid-based auxins (picloram) and quinolinecarboxylic acids (quinclorac). The atlas demonstrates why some widely used auxin herbicides are not, or are very poor substrates. We list molecular descriptors for AUX1 substrates and discuss our findings in terms of herbicide resistance management.
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Affiliation(s)
- Klara Hoyerova
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Rozvojova 263, 165 02, Prague 6, Czech Republic
| | - Petr Hosek
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Rozvojova 263, 165 02, Prague 6, Czech Republic
| | - Mussa Quareshy
- School of Life Sciences, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK
| | - Jun Li
- Department of Pesticide Science, College of Crop Protection, Nanjing Agricultural University, Weigang 1, Nanjing, Jiangsu Province, China
| | - Petr Klima
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Rozvojova 263, 165 02, Prague 6, Czech Republic
| | - Martin Kubes
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Rozvojova 263, 165 02, Prague 6, Czech Republic
- Department of Chemical Biology and Genetics, Centre of the Region Haná for Biotechnological and Agricultural Research, Šlechtitelů 241/27, 78371, Olomouc, Czech Republic
| | - Antony A Yemm
- School of Life Sciences, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK
| | - Paul Neve
- Rothamsted Research, Harpenden, AL5 2JQ, UK
| | - Ashutosh Tripathi
- School of Life Sciences, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK
| | - Malcolm J Bennett
- Plant Sciences Division and Centre for Plant Integrative Biology, School of Biological Sciences, The University of Nottingham, Sutton Bonnington Campus, Loughborough, LE12 5RD, UK
| | - Richard M Napier
- School of Life Sciences, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK
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15
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Cano A, Sánchez-García AB, Albacete A, González-Bayón R, Justamante MS, Ibáñez S, Acosta M, Pérez-Pérez JM. Enhanced Conjugation of Auxin by GH3 Enzymes Leads to Poor Adventitious Rooting in Carnation Stem Cuttings. FRONTIERS IN PLANT SCIENCE 2018; 9:566. [PMID: 29755501 PMCID: PMC5932754 DOI: 10.3389/fpls.2018.00566] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 04/10/2018] [Indexed: 05/05/2023]
Abstract
Commercial carnation (Dianthus caryophyllus) cultivars are vegetatively propagated from axillary stem cuttings through adventitious rooting; a process which is affected by complex interactions between nutrient and hormone levels and is strongly genotype-dependent. To deepen our understanding of the regulatory events controlling this process, we performed a comparative study of adventitious root (AR) formation in two carnation cultivars with contrasting rooting performance, "2101-02 MFR" and "2003 R 8", as well as in the reference cultivar "Master". We provided molecular evidence that localized auxin response in the stem cutting base was required for efficient adventitious rooting in this species, which was dynamically established by polar auxin transport from the leaves. In turn, the bad-rooting behavior of the "2003 R 8" cultivar was correlated with enhanced synthesis of indole-3-acetic acid conjugated to aspartic acid by GH3 proteins in the stem cutting base. Treatment of stem cuttings with a competitive inhibitor of GH3 enzyme activity significantly improved rooting of "2003 R 8". Our results allowed us to propose a working model where endogenous auxin homeostasis regulated by GH3 proteins accounts for the cultivar dependency of AR formation in carnation stem cuttings.
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Affiliation(s)
- Antonio Cano
- Departamento de Biología Vegetal (Fisiología Vegetal), Universidad de Murcia, Murcia, Spain
| | | | - Alfonso Albacete
- Departamento de Nutrición Vegetal, Centro de Edafología y Biología Aplicada del Segura-Consejo Superior de Investigaciones Científicas, Murcia, Spain
| | | | | | - Sergio Ibáñez
- Instituto de Bioingeniería, Universidad Miguel Hernández, Elche, Spain
| | - Manuel Acosta
- Departamento de Biología Vegetal (Fisiología Vegetal), Universidad de Murcia, Murcia, Spain
| | - José Manuel Pérez-Pérez
- Instituto de Bioingeniería, Universidad Miguel Hernández, Elche, Spain
- *Correspondence: José Manuel Pérez-Pérez, arolab.edu.umh.es;
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16
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Liu Y, Dong Q, Kita D, Huang JB, Liu G, Wu X, Zhu X, Cheung AY, Wu HM, Tao LZ. RopGEF1 Plays a Critical Role in Polar Auxin Transport in Early Development. PLANT PHYSIOLOGY 2017; 175:157-171. [PMID: 28698357 PMCID: PMC5580763 DOI: 10.1104/pp.17.00697] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 07/07/2017] [Indexed: 05/20/2023]
Abstract
Polar auxin transport, facilitated by the combined activities of auxin influx and efflux carriers to maintain asymmetric auxin distribution, is essential for plant growth and development. Here, we show that Arabidopsis (Arabidopsis thaliana) RopGEF1, a guanine nucleotide exchange factor and activator of Rho GTPases of plants (ROPs), is critically involved in polar distribution of auxin influx carrier AUX1 and differential accumulation of efflux carriers PIN7 and PIN2 and is important for embryo and early seedling development when RopGEF1 is prevalently expressed. Knockdown or knockout of RopGEF1 induces embryo defects, cotyledon vein breaks, and delayed root gravity responses. Altered expression from the auxin response reporter DR5rev:GFP in the root pole of RopGEF1-deficient embryos and loss of asymmetric distribution of DR5rev:GFP in their gravistimulated root tips suggest that auxin distribution is affected in ropgef1 mutants. This is reflected by the polarity of AUX1 being altered in ropgef1 embryos and roots, shifting from the normal apical membrane location to a basal location in embryo central vascular and root protophloem cells and also reduced PIN7 accumulation at embryos and altered PIN2 distribution in gravistimulated roots of mutant seedlings. In establishing that RopGEF1 is critical for AUX1 localization and PIN differential accumulation, our results reveal a role for RopGEF1 in cell polarity and polar auxin transport whereby it imapcts auxin-mediated plant growth and development.
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Affiliation(s)
- Yuting Liu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou 510642, China
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou 510642, China
| | - Qingkun Dong
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou 510642, China
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou 510642, China
| | - Daniel Kita
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts 01003
| | - Jia-Bao Huang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou 510642, China
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou 510642, China
| | - Guolan Liu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou 510642, China
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou 510642, China
| | - Xiaowei Wu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou 510642, China
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou 510642, China
| | - Xiaoyue Zhu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou 510642, China
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou 510642, China
| | - Alice Y Cheung
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts 01003
| | - Hen-Ming Wu
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts 01003
| | - Li-Zhen Tao
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou 510642, China
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou 510642, China
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17
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Hu Y, Vandenbussche F, Van Der Straeten D. Regulation of seedling growth by ethylene and the ethylene-auxin crosstalk. PLANTA 2017; 245:467-489. [PMID: 28188422 DOI: 10.1007/s00425-017-2651-6] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 01/08/2017] [Indexed: 05/06/2023]
Abstract
This review highlights that the auxin gradient, established by local auxin biosynthesis and transport, can be controlled by ethylene, and steers seedling growth. A better understanding of the mechanisms in Arabidopsis will increase potential applications in crop species. In dark-grown Arabidopsis seedlings, exogenous ethylene treatment triggers an exaggeration of the apical hook, the inhibition of both hypocotyl and root elongation, and radial swelling of the hypocotyl. These features are predominantly based on the differential cell elongation in different cells/tissues mediated by an auxin gradient. Interestingly, the physiological responses regulated by ethylene and auxin crosstalk can be either additive or synergistic, as in primary root and root hair elongation, or antagonistic, as in hypocotyl elongation. This review focuses on the crosstalk of these two hormones at the seedling stage. Before illustrating the crosstalk, ethylene and auxin biosynthesis, metabolism, transport and signaling are briefly discussed.
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Affiliation(s)
- Yuming Hu
- Laboratory of Functional Plant Biology, Department of Biology, Ghent University, K.L. Ledeganckstraat 35, 9000, Ghent, Belgium
| | - Filip Vandenbussche
- Laboratory of Functional Plant Biology, Department of Biology, Ghent University, K.L. Ledeganckstraat 35, 9000, Ghent, Belgium
| | - Dominique Van Der Straeten
- Laboratory of Functional Plant Biology, Department of Biology, Ghent University, K.L. Ledeganckstraat 35, 9000, Ghent, Belgium.
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18
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Klíma P, Laňková M, Zažímalová E. Inhibitors of plant hormone transport. PROTOPLASMA 2016; 253:1391-1404. [PMID: 26494150 DOI: 10.1007/s00709-015-0897-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 10/09/2015] [Indexed: 06/05/2023]
Abstract
Here we present an overview of what is known about endogenous plant compounds that act as inhibitors of hormonal transport processes in plants, about their identity and mechanism of action. We have also summarized commonly and less commonly used compounds of non-plant origin and synthetic drugs that show at least partial 'specificity' to transport or transporters of particular phytohormones. Our main attention is focused on the inhibitors of auxin transport. The urgent need to understand precisely the molecular mechanism of action of these inhibitors is highlighted.
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Affiliation(s)
- Petr Klíma
- Institute of Experimental Botany, The Czech Academy of Sciences, Rozvojová 263, 165 02, Prague 6, Czech Republic
| | - Martina Laňková
- Institute of Experimental Botany, The Czech Academy of Sciences, Rozvojová 263, 165 02, Prague 6, Czech Republic
| | - Eva Zažímalová
- Institute of Experimental Botany, The Czech Academy of Sciences, Rozvojová 263, 165 02, Prague 6, Czech Republic.
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19
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Laňková M, Humpolíčková J, Vosolsobě S, Cit Z, Lacek J, Čovan M, Čovanová M, Hof M, Petrášek J. Determination of Dynamics of Plant Plasma Membrane Proteins with Fluorescence Recovery and Raster Image Correlation Spectroscopy. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2016; 22:290-9. [PMID: 27041337 DOI: 10.1017/s1431927616000568] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A number of fluorescence microscopy techniques are described to study dynamics of fluorescently labeled proteins, lipids, nucleic acids, and whole organelles. However, for studies of plant plasma membrane (PM) proteins, the number of these techniques is still limited because of the high complexity of processes that determine the dynamics of PM proteins and the existence of cell wall. Here, we report on the usage of raster image correlation spectroscopy (RICS) for studies of integral PM proteins in suspension-cultured tobacco cells and show its potential in comparison with the more widely used fluorescence recovery after photobleaching method. For RICS, a set of microscopy images is obtained by single-photon confocal laser scanning microscopy (CLSM). Fluorescence fluctuations are subsequently correlated between individual pixels and the information on protein mobility are extracted using a model that considers processes generating the fluctuations such as diffusion and chemical binding reactions. As we show here using an example of two integral PM transporters of the plant hormone auxin, RICS uncovered their distinct short-distance lateral mobility within the PM that is dependent on cytoskeleton and sterol composition of the PM. RICS, which is routinely accessible on modern CLSM instruments, thus represents a valuable approach for studies of dynamics of PM proteins in plants.
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Affiliation(s)
- Martina Laňková
- 1Institute of Experimental Botany,Academy of Sciences of the Czech Republic,Rozvojová 263,165 02 Prague 6,Czech Republic
| | - Jana Humpolíčková
- 2J. Heyrovský Institute of Physical Chemistry,Academy of Sciences of the Czech Republic,Dolejškova 2155/3,182 23 Prague 8,Czech Republic
| | - Stanislav Vosolsobě
- 3Department of Experimental Plant Biology, Faculty of Science,Charles University,Viničná 5,128 44 Prague 2,Czech Republic
| | - Zdeněk Cit
- 1Institute of Experimental Botany,Academy of Sciences of the Czech Republic,Rozvojová 263,165 02 Prague 6,Czech Republic
| | - Jozef Lacek
- 1Institute of Experimental Botany,Academy of Sciences of the Czech Republic,Rozvojová 263,165 02 Prague 6,Czech Republic
| | - Martin Čovan
- 1Institute of Experimental Botany,Academy of Sciences of the Czech Republic,Rozvojová 263,165 02 Prague 6,Czech Republic
| | - Milada Čovanová
- 1Institute of Experimental Botany,Academy of Sciences of the Czech Republic,Rozvojová 263,165 02 Prague 6,Czech Republic
| | - Martin Hof
- 2J. Heyrovský Institute of Physical Chemistry,Academy of Sciences of the Czech Republic,Dolejškova 2155/3,182 23 Prague 8,Czech Republic
| | - Jan Petrášek
- 1Institute of Experimental Botany,Academy of Sciences of the Czech Republic,Rozvojová 263,165 02 Prague 6,Czech Republic
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20
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Eckstein A, Krzeszowiec W, Waligórski P, Gabryś H. Auxin and chloroplast movements. PHYSIOLOGIA PLANTARUM 2016; 156:351-366. [PMID: 26467664 DOI: 10.1111/ppl.12396] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2015] [Accepted: 09/14/2015] [Indexed: 06/05/2023]
Abstract
Auxin is involved in a wide spectrum of physiological processes in plants, including responses controlled by the blue light photoreceptors phototropins: phototropic bending and stomatal movement. However, the role of auxin in phototropin-mediated chloroplast movements has never been studied. To address this question we searched for potential interactions between auxin and the chloroplast movement signaling pathway using different experimental approaches and two model plants, Arabidopsis thaliana and Nicotiana tabacum. We observed that the disturbance of auxin homeostasis by shoot decapitation caused a decrease in chloroplast movement parameters, which could be rescued by exogenous auxin application. In several cases, the impairment of polar auxin transport, by chemical inhibitors or in auxin carrier mutants, had a similar negative effect on chloroplast movements. This inhibition was not correlated with changes in auxin levels. Chloroplast relocations were also affected by the antiauxin p-chlorophenoxyisobutyric acid and mutations in genes encoding some of the elements of the SCF(TIR1)-Aux/IAA auxin receptor complex. The observed changes in chloroplast movement parameters are not prominent, which points to a modulatory role of auxin in this process. Taken together, the obtained results suggest that auxin acts indirectly to regulate chloroplast movements, presumably by regulating gene expression via the SCF(TIR1)-Aux/IAA-ARF pathway. Auxin does not seem to be involved in controlling the expression of phototropins.
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Affiliation(s)
- Aleksandra Eckstein
- Department of Plant Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland
| | - Weronika Krzeszowiec
- Department of Plant Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland
| | - Piotr Waligórski
- The Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Kraków, Poland
| | - Halina Gabryś
- Department of Plant Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland
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21
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Zhao H, Ma T, Wang X, Deng Y, Ma H, Zhang R, Zhao J. OsAUX1 controls lateral root initiation in rice (Oryza sativa L.). PLANT, CELL & ENVIRONMENT 2015; 38:2208-22. [PMID: 25311360 DOI: 10.1111/pce.12467] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Accepted: 10/01/2014] [Indexed: 05/06/2023]
Abstract
Polar auxin transport, mediated by influx and efflux transporters, controls many aspects of plant growth and development. The auxin influx carriers in Arabidopsis have been shown to control lateral root development and gravitropism, but little is known about these proteins in rice. This paper reports on the functional characterization of OsAUX1. Three OsAUX1 T-DNA insertion mutants and RNAi knockdown transgenic plants reduced lateral root initiation compared with wild-type (WT) plants. OsAUX1 overexpression plants exhibited increased lateral root initiation and OsAUX1 was highly expressed in lateral roots and lateral root primordia. Similarly, the auxin reporter, DR5-GUS, was expressed at lower levels in osaux1 than in the WT plants, which indicated that the auxin levels in the mutant roots had decreased. Exogenous 1-naphthylacetic acid (NAA) treatment rescued the defective phenotype in osaux1-1 plants, whereas indole-3-acetic acid (IAA) and 2,4-D could not, which suggested that OsAUX1 was a putative auxin influx carrier. The transcript levels of several auxin signalling genes and cell cycle genes significantly declined in osaux1, hinting that the regulatory role of OsAUX1 may be mediated by auxin signalling and cell cycle genes. Overall, our results indicated that OsAUX1 was involved in polar auxin transport and functioned to control auxin-mediated lateral root initiation in rice.
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Affiliation(s)
- Heming Zhao
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Tengfei Ma
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Xin Wang
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Yingtian Deng
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Haoli Ma
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Rongsheng Zhang
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Jie Zhao
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, 430072, China
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Cieslak M, Runions A, Prusinkiewicz P. Auxin-driven patterning with unidirectional fluxes. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:5083-102. [PMID: 26116915 PMCID: PMC4513925 DOI: 10.1093/jxb/erv262] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The plant hormone auxin plays an essential role in the patterning of plant structures. Biological hypotheses supported by computational models suggest that auxin may fulfil this role by regulating its own transport, but the plausibility of previously proposed models has been questioned. We applied the notion of unidirectional fluxes and the formalism of Petri nets to show that the key modes of auxin-driven patterning-the formation of convergence points and the formation of canals-can be implemented by biochemically plausible networks, with the fluxes measured by dedicated tally molecules or by efflux and influx carriers themselves. Common elements of these networks include a positive feedback of auxin efflux on the allocation of membrane-bound auxin efflux carriers (PIN proteins), and a modulation of this allocation by auxin in the extracellular space. Auxin concentration in the extracellular space is the only information exchanged by the cells. Canalization patterns are produced when auxin efflux and influx act antagonistically: an increase in auxin influx or concentration in the extracellular space decreases the abundance of efflux carriers in the adjacent segment of the membrane. In contrast, convergence points emerge in networks in which auxin efflux and influx act synergistically. A change in a single reaction rate may result in a dynamic switch between these modes, suggesting plausible molecular implementations of coordinated patterning of organ initials and vascular strands predicted by the dual polarization theory.
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Affiliation(s)
- Mikolaj Cieslak
- Department of Computer Science, University of Calgary, 2500 University Dr. N.W., Calgary, AB T2N 1N4, Canada
| | - Adam Runions
- Department of Computer Science, University of Calgary, 2500 University Dr. N.W., Calgary, AB T2N 1N4, Canada
| | - Przemyslaw Prusinkiewicz
- Department of Computer Science, University of Calgary, 2500 University Dr. N.W., Calgary, AB T2N 1N4, Canada
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Żur I, Dubas E, Krzewska M, Janowiak F. Current insights into hormonal regulation of microspore embryogenesis. FRONTIERS IN PLANT SCIENCE 2015; 6:424. [PMID: 26113852 PMCID: PMC4462098 DOI: 10.3389/fpls.2015.00424] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 05/26/2015] [Indexed: 05/24/2023]
Abstract
Plant growth regulator (PGR) crosstalk and interaction with the plant's genotype and environmental factors play a crucial role in microspore embryogenesis (ME), controlling microspore-derived embryo differentiation and development as well as haploid/doubled haploid plant regeneration. The complexity of the PGR network which could exist at the level of biosynthesis, distribution, gene expression or signaling pathways, renders the creation of an integrated model of ME-control crosstalk impossible at present. However, the analysis of the published data together with the results received recently with the use of modern analytical techniques brings new insights into hormonal regulation of this process. This review presents a short historical overview of the most important milestones in the recognition of hormonal requirements for effective ME in the most important crop plant species and complements it with new concepts that evolved over the last decade of ME studies.
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Affiliation(s)
- Iwona Żur
- The Franciszek Górski Institute of Plant Physiology, Polish Academy of SciencesKraków, Poland
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24
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Zelinová V, Alemayehu A, Bočová B, Huttová J, Tamás L. Cadmium-induced reactive oxygen species generation, changes in morphogenic responses and activity of some enzymes in barley root tip are regulated by auxin. Biologia (Bratisl) 2015. [DOI: 10.1515/biolog-2015-0035] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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25
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Shen C, Yue R, Sun T, Zhang L, Yang Y, Wang H. OsARF16, a transcription factor regulating auxin redistribution, is required for iron deficiency response in rice (Oryza sativa L.). PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2015; 231:148-58. [PMID: 25576000 DOI: 10.1016/j.plantsci.2014.12.003] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2014] [Revised: 11/24/2014] [Accepted: 12/01/2014] [Indexed: 05/18/2023]
Abstract
Plant response to iron deficiency is the most important feature for survival in Fe-limited soils. Several phytohormones, including auxin, are involved in iron uptake and homeostasis. However, the mechanisms behind how auxin participates in the iron deficiency response in rice are largely unknown. We found that OsARF16 was involved in the iron deficiency response and the induction of iron deficiency response genes. Most Fe-deficient symptoms could be partially restored in the osarf16 mutant, including dwarfism, photosynthesis decline, a reduction in iron content and root system architecture (RSA) regulation. OsARF16 expression was induced in the roots and shoots by Fe deprivation. Restoration of the phenotype could also be mimicked by 1-NOA, an auxin influx inhibitor. Furthermore, the qRT-PCR data indicated that the induction of Fe-deficiency response genes by iron deficiency was more compromised in the osarf16 mutant than in Nipponbare. In conclusion, osarf16, an auxin insensitive mutant, was involved in iron deficiency response in rice. Our results reveal a new biological function for OsARF16 and provide important information on how ARF-medicated auxin signaling affects iron signaling and the iron deficiency response. This work may help us to improve production or increased Fe nutrition of rice to iron deficiency by regulating auxin signaling.
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Affiliation(s)
- Chenjia Shen
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China.
| | - Runqing Yue
- Henan Academy of Agricultural Sciences, Zhengzhou 450002, China
| | - Tao Sun
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China
| | - Lei Zhang
- Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430, USA
| | - Yanjun Yang
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China
| | - Huizhong Wang
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China.
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26
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Robert HS, Grunewald W, Sauer M, Cannoot B, Soriano M, Swarup R, Weijers D, Bennett M, Boutilier K, Friml J. Plant embryogenesis requires AUX/LAX-mediated auxin influx. Development 2015; 142:702-11. [PMID: 25617434 DOI: 10.1242/dev.115832] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The plant hormone auxin and its directional transport are known to play a crucial role in defining the embryonic axis and subsequent development of the body plan. Although the role of PIN auxin efflux transporters has been clearly assigned during embryonic shoot and root specification, the role of the auxin influx carriers AUX1 and LIKE-AUX1 (LAX) proteins is not well established. Here, we used chemical and genetic tools on Brassica napus microspore-derived embryos and Arabidopsis thaliana zygotic embryos, and demonstrate that AUX1, LAX1 and LAX2 are required for both shoot and root pole formation, in concert with PIN efflux carriers. Furthermore, we uncovered a positive-feedback loop between MONOPTEROS (ARF5)-dependent auxin signalling and auxin transport. This MONOPTEROS-dependent transcriptional regulation of auxin influx (AUX1, LAX1 and LAX2) and auxin efflux (PIN1 and PIN4) carriers by MONOPTEROS helps to maintain proper auxin transport to the root tip. These results indicate that auxin-dependent cell specification during embryo development requires balanced auxin transport involving both influx and efflux mechanisms, and that this transport is maintained by a positive transcriptional feedback on auxin signalling.
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Affiliation(s)
- Hélène S Robert
- Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB) and Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium Mendel Centre for Genomics and Proteomics of Plants Systems, CEITEC MU - Central European Institute of Technology, Masaryk University, 625 00 Brno, Czech Republic
| | - Wim Grunewald
- Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB) and Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium
| | - Michael Sauer
- University of Potsdam, Institute of Biochemistry and Biology, D-14476 Potsdam, Germany Departamento Molecular de Plantas, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Cientificas, 28049 Madrid, Spain
| | - Bernard Cannoot
- Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB) and Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium
| | - Mercedes Soriano
- Wageningen University and Research Centre, P.O. Box 619, 6700 AP Wageningen, The Netherlands
| | - Ranjan Swarup
- School of Biosciences and Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, UK
| | - Dolf Weijers
- Laboratory of Biochemistry, Wageningen University, 6703 HA Wageningen, The Netherlands
| | - Malcolm Bennett
- School of Biosciences and Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, UK
| | - Kim Boutilier
- Wageningen University and Research Centre, P.O. Box 619, 6700 AP Wageningen, The Netherlands
| | - Jiří Friml
- Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB) and Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium Mendel Centre for Genomics and Proteomics of Plants Systems, CEITEC MU - Central European Institute of Technology, Masaryk University, 625 00 Brno, Czech Republic Institute of Science and Technology Austria (IST Austria), 3400 Klosterneuburg, Austria
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27
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Ma Q, Robert S. Auxin biology revealed by small molecules. PHYSIOLOGIA PLANTARUM 2014; 151:25-42. [PMID: 24252105 DOI: 10.1111/ppl.12128] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Revised: 11/07/2013] [Accepted: 11/08/2013] [Indexed: 05/08/2023]
Abstract
The plant hormone auxin regulates virtually every aspect of plant growth and development and unraveling its molecular and cellular modes of action is fundamental for plant biology research. Chemical genomics is the use of small molecules to modify protein functions. This approach currently rises as a powerful technology for basic research. Small compounds with auxin-like activities or affecting auxin-mediated biological processes have been widely used in auxin research. They can serve as a tool complementary to genetic and genomic methods, facilitating the identification of an array of components modulating auxin metabolism, transport and signaling. The employment of high-throughput screening technologies combined with informatics-based chemical design and organic chemical synthesis has since yielded many novel small molecules with more instantaneous, precise and specific functionalities. By applying those small molecules, novel molecular targets can be isolated to further understand and dissect auxin-related pathways and networks that otherwise are too complex to be elucidated only by gene-based methods. Here, we will review examples of recently characterized molecules used in auxin research, highlight the strategies of unraveling the mechanisms of these small molecules and discuss future perspectives of small molecule applications in auxin biology.
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Affiliation(s)
- Qian Ma
- Umeå Plant Science Center, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-901 83, Umeå, Sweden
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28
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Seifertová D, Skůpa P, Rychtář J, Laňková M, Pařezová M, Dobrev PI, Hoyerová K, Petrášek J, Zažímalová E. Characterization of transmembrane auxin transport in Arabidopsis suspension-cultured cells. JOURNAL OF PLANT PHYSIOLOGY 2014; 171:429-37. [PMID: 24594395 DOI: 10.1016/j.jplph.2013.09.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2013] [Revised: 09/24/2013] [Accepted: 09/28/2013] [Indexed: 05/21/2023]
Abstract
Polar auxin transport is a crucial process for control and coordination of plant development. Studies of auxin transport through plant tissues and organs showed that auxin is transported by a combination of phloem flow and the active, carrier-mediated cell-to-cell transport. Since plant organs and even tissues are too complex for determination of the kinetics of carrier-mediated auxin uptake and efflux on the cellular level, simplified models of cell suspension cultures are often used, and several tobacco cell lines have been established for auxin transport assays. However, there are very few data available on the specificity and kinetics of auxin transport across the plasma membrane for Arabidopsis thaliana suspension-cultured cells. In this report, the characteristics of carrier-mediated uptake (influx) and efflux for the native auxin indole-3-acetic acid and synthetic auxins, naphthalene-1-acetic and 2,4-dichlorophenoxyacetic acids (NAA and 2,4-D, respectively) in A. thaliana ecotype Landsberg erecta suspension-cultured cells (LE line) are provided. By auxin competition assays and inhibitor treatments, we show that, similarly to tobacco cells, uptake carriers have high affinity towards 2,4-D and that NAA is a good tool for studies of auxin efflux in LE cells. In contrast to tobacco cells, metabolic profiling showed that only a small proportion of NAA is metabolized in LE cells. These results show that the LE cell line is a useful experimental system for measurements of kinetics of auxin carriers on the cellular level that is complementary to tobacco cells.
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Affiliation(s)
- Daniela Seifertová
- Institute of Experimental Botany ASCR, Rozvojová 263, 165 02 Prague 6, Czech Republic.
| | - Petr Skůpa
- Institute of Experimental Botany ASCR, Rozvojová 263, 165 02 Prague 6, Czech Republic.
| | - Jan Rychtář
- Department of Mathematics and Statistics, The University of North Carolina at Greensboro, 130 Petty Building, NC 27403, USA.
| | - Martina Laňková
- Institute of Experimental Botany ASCR, Rozvojová 263, 165 02 Prague 6, Czech Republic.
| | - Markéta Pařezová
- Institute of Experimental Botany ASCR, Rozvojová 263, 165 02 Prague 6, Czech Republic.
| | - Petre I Dobrev
- Institute of Experimental Botany ASCR, Rozvojová 263, 165 02 Prague 6, Czech Republic.
| | - Klára Hoyerová
- Institute of Experimental Botany ASCR, Rozvojová 263, 165 02 Prague 6, Czech Republic.
| | - Jan Petrášek
- Institute of Experimental Botany ASCR, Rozvojová 263, 165 02 Prague 6, Czech Republic.
| | - Eva Zažímalová
- Institute of Experimental Botany ASCR, Rozvojová 263, 165 02 Prague 6, Czech Republic.
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Petrášek J, Laňková M, Zažímalová E. Determination of auxin transport parameters on the cellular level. Methods Mol Biol 2014; 1056:241-53. [PMID: 24306878 DOI: 10.1007/978-1-62703-592-7_22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The accumulation of radioactively labelled compounds in cells is frequently used for the determination of activities of various transport systems located at the plasma membrane, including the system for carrier-mediated transport of plant hormone auxin. The measurements of auxin transport could be performed on the tissue level as well, but for more precise quantitative analysis of activity of individual auxin carriers the model of plant cell cultures represents an invaluable tool. Here, we describe the method for the determination of the activities of auxin influx and efflux carriers in plant cells grown in a suspension using radiolabelled synthetic auxins 2,4-dichlorophenoxyacetic acid (2,4-D) and naphthalene-1-acetic acid (NAA). By making use of specific inhibitors of active auxin influx and efflux, as well as cell lines overexpressing or silencing particular auxin carriers, this method allows the determination of kinetic parameters of auxin flow across the plasma membrane and the activity of those carriers.
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Affiliation(s)
- Jan Petrášek
- Institute of Experimental Botany, ASC, Prague, Czech Republic
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Simon S, Kubeš M, Baster P, Robert S, Dobrev PI, Friml J, Petrášek J, Zažímalová E. Defining the selectivity of processes along the auxin response chain: a study using auxin analogues. THE NEW PHYTOLOGIST 2013; 200:1034-48. [PMID: 23914741 DOI: 10.1111/nph.12437] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Accepted: 06/25/2013] [Indexed: 05/08/2023]
Abstract
The mode of action of auxin is based on its non-uniform distribution within tissues and organs. Despite the wide use of several auxin analogues in research and agriculture, little is known about the specificity of different auxin-related transport and signalling processes towards these compounds. Using seedlings of Arabidopsis thaliana and suspension-cultured cells of Nicotiana tabacum (BY-2), the physiological activity of several auxin analogues was investigated, together with their capacity to induce auxin-dependent gene expression, to inhibit endocytosis and to be transported across the plasma membrane. This study shows that the specificity criteria for different auxin-related processes vary widely. Notably, the special behaviour of some synthetic auxin analogues suggests that they might be useful tools in investigations of the molecular mechanism of auxin action. Thus, due to their differential stimulatory effects on DR5 expression, indole-3-propionic (IPA) and 2,4,5-trichlorophenoxy acetic (2,4,5-T) acids can serve in studies of TRANSPORT INHIBITOR RESPONSE 1/AUXIN SIGNALLING F-BOX (TIR1/AFB)-mediated auxin signalling, and 5-fluoroindole-3-acetic acid (5-F-IAA) can help to discriminate between transcriptional and non-transcriptional pathways of auxin signalling. The results demonstrate that the major determinants for the auxin-like physiological potential of a particular compound are very complex and involve its chemical and metabolic stability, its ability to distribute in tissues in a polar manner and its activity towards auxin signalling machinery.
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Affiliation(s)
- Sibu Simon
- Institute of Experimental Botany, The Academy of Sciences of the Czech Republic, Rozvojová 263, 16502, Prague 6, Czech Republic; Department of Plant Systems Biology, VIB and Department of Plant Biotechnology and Genetics, Ghent University, 9052, Ghent, Belgium; Developmental and Cell Physiology of Plants, Institute of Science and Technology (IST Austria), 3400, Klosterneuburg, Austria
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Durst S, Nick P, Maisch J. Nicotiana tabacum actin-depolymerizing factor 2 is involved in actin-driven, auxin-dependent patterning. JOURNAL OF PLANT PHYSIOLOGY 2013; 170:1057-66. [PMID: 23545293 DOI: 10.1016/j.jplph.2013.03.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Revised: 03/07/2013] [Accepted: 03/07/2013] [Indexed: 05/27/2023]
Abstract
Polar transport of auxin has been identified as a central element of pattern formation. To address the underlying cellular mechanisms, we use the tobacco cell line (Nicotiana tabacum L. cv. Bright Yellow 2; BY-2) as model. We showed previously that cell divisions within a cell file are synchronized by polar auxin flow, linked to the organization of actin filaments (AF) which, in turn, is modified via actin-binding proteins (ABPs). From a preparatory study for disturbed division synchrony in cell lines overexpressing different ABPs, we identified the actin depolymerizing factor 2 (ADF2). A cell line overexpressing GFP-NtADF2 was specifically affected in division synchrony. The cell division pattern could be rescued by addition of Phosphatidylinositol 4,5-bisphosphate (PIP2) or by phalloidin. These observations allow to draw first conclusions on the pathway linking auxin signalling via actin reorganization to synchronized cell division placing the regulation of cortical actin turnover by ADF2 into the focus.
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Affiliation(s)
- Steffen Durst
- Botanical Institute, Molecular Cell Biology, Karlsruhe Institute of Technology (KIT), Kaiserstrasse 2, D-76131 Karlsruhe, Germany
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Barbez E, Laňková M, Pařezová M, Maizel A, Zažímalová E, Petrášek J, Friml J, Kleine-Vehn J. Single-cell-based system to monitor carrier driven cellular auxin homeostasis. BMC PLANT BIOLOGY 2013; 13:20. [PMID: 23379388 PMCID: PMC3598821 DOI: 10.1186/1471-2229-13-20] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Accepted: 01/31/2013] [Indexed: 05/06/2023]
Abstract
BACKGROUND Abundance and distribution of the plant hormone auxin play important roles in plant development. Besides other metabolic processes, various auxin carriers control the cellular level of active auxin and, hence, are major regulators of cellular auxin homeostasis. Despite the developmental importance of auxin transporters, a simple medium-to-high throughput approach to assess carrier activities is still missing. Here we show that carrier driven depletion of cellular auxin correlates with reduced nuclear auxin signaling in tobacco Bright Yellow-2 (BY-2) cell cultures. RESULTS We developed an easy to use transient single-cell-based system to detect carrier activity. We use the relative changes in signaling output of the auxin responsive promoter element DR5 to indirectly visualize auxin carrier activity. The feasibility of the transient approach was demonstrated by pharmacological and genetic interference with auxin signaling and transport. As a proof of concept, we provide visual evidence that the prominent auxin transport proteins PIN-FORMED (PIN)2 and PIN5 regulate cellular auxin homeostasis at the plasma membrane and endoplasmic reticulum (ER), respectively. Our data suggest that PIN2 and PIN5 have different sensitivities to the auxin transport inhibitor 1-naphthylphthalamic acid (NPA). Also the putative PIN-LIKES (PILS) auxin carrier activity at the ER is insensitive to NPA in our system, indicating that NPA blocks intercellular, but not intracellular auxin transport. CONCLUSIONS This single-cell-based system is a useful tool by which the activity of putative auxin carriers, such as PINs, PILS and WALLS ARE THIN1 (WAT1), can be indirectly visualized in a medium-to-high throughput manner. Moreover, our single cell system might be useful to investigate also other hormonal signaling pathways, such as cytokinin.
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Affiliation(s)
- Elke Barbez
- Department of Plant Systems Biology, VIB and Department of Plant Biotechnology and Genetics, Ghent University, 9052, Gent, Belgium
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna (BOKU), 1190, Vienna, Austria
| | - Martina Laňková
- Institute of Experimental Botany, The Academy of Sciences of the Czech Republic, 16502, Praha 6, Czech Republic
| | - Markéta Pařezová
- Institute of Experimental Botany, The Academy of Sciences of the Czech Republic, 16502, Praha 6, Czech Republic
| | - Alexis Maizel
- Department of Stem Cell Biology, Center for Organismal Studies, University of Heidelberg, 69120, Heidelberg, Germany
| | - Eva Zažímalová
- Institute of Experimental Botany, The Academy of Sciences of the Czech Republic, 16502, Praha 6, Czech Republic
| | - Jan Petrášek
- Institute of Experimental Botany, The Academy of Sciences of the Czech Republic, 16502, Praha 6, Czech Republic
| | - Jiří Friml
- Department of Plant Systems Biology, VIB and Department of Plant Biotechnology and Genetics, Ghent University, 9052, Gent, Belgium
- Department of Functional Genomics and Proteomics, Faculty of Science, and CEITEC, Masaryk University, Kamenice 5, CZ-62500, Brno, Czech Republic
| | - Jürgen Kleine-Vehn
- Department of Plant Systems Biology, VIB and Department of Plant Biotechnology and Genetics, Ghent University, 9052, Gent, Belgium
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna (BOKU), 1190, Vienna, Austria
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Xu W, Jia L, Shi W, Liang J, Zhou F, Li Q, Zhang J. Abscisic acid accumulation modulates auxin transport in the root tip to enhance proton secretion for maintaining root growth under moderate water stress. THE NEW PHYTOLOGIST 2013; 197:139-150. [PMID: 23106247 DOI: 10.1111/nph.12004] [Citation(s) in RCA: 148] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 09/16/2012] [Indexed: 05/18/2023]
Abstract
Maintenance of root growth is essential for plant adaptation to soil drying. Here, we tested the hypothesis that auxin transport is involved in mediating ABA's modulation by activating proton secretion in the root tip to maintain root growth under moderate water stress. Rice and Arabidopsis plants were raised under a hydroponic system and subjected to moderate water stress (-0.47 MPa) with polyethylene glycol (PEG). ABA accumulation, auxin transport and plasma membrane H(+)-ATPase activity at the root tip were monitored in addition to the primary root elongation and root hair density. We found that moderate water stress increases ABA accumulation and auxin transport in the root apex. Additionally, ABA modulation is involved in the regulation of auxin transport in the root tip. The transported auxin activates the plasma membrane H(+)-ATPase to release more protons along the root tip in its adaption to moderate water stress. The proton secretion in the root tip is essential in maintaining or promoting primary root elongation and root hair development under moderate water stress. These results suggest that ABA accumulation modulates auxin transport in the root tip, which enhances proton secretion for maintaining root growth under moderate water stress.
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Affiliation(s)
- Weifeng Xu
- School of Life Sciences and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Hong Kong, Hong Kong
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China
| | - Liguo Jia
- School of Life Sciences and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Hong Kong, Hong Kong
- College of Agronomy, Inner Mongolia Agricultural University, Huhhot, China
| | - Weiming Shi
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China
| | - Jiansheng Liang
- College of Bioscience and Biotechnology, Yangzhou University, Yangzhou, China
| | - Feng Zhou
- College of Life Sciences, South China Agricultural University, Guangzhou, China
| | - Qianfeng Li
- School of Life Sciences and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Hong Kong, Hong Kong
| | - Jianhua Zhang
- School of Life Sciences and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Hong Kong, Hong Kong
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Boot KJM, Libbenga KR, Hille SC, Offringa R, van Duijn B. Polar auxin transport: an early invention. JOURNAL OF EXPERIMENTAL BOTANY 2012; 63:4213-8. [PMID: 22473986 PMCID: PMC3398450 DOI: 10.1093/jxb/ers106] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Revised: 03/14/2012] [Accepted: 03/19/2012] [Indexed: 05/20/2023]
Abstract
In higher plants, cell-to-cell polar auxin transport (PAT) of the phytohormone auxin, indole-3-acetic acid (IAA), generates maxima and minima that direct growth and development. Although IAA is present in all plant phyla, PAT has only been detected in land plants, the earliest being the Bryophytes. Charophyta, a group of freshwater green algae, are among the first multicellular algae with a land plant-like phenotype and are ancestors to land plants. IAA has been detected in members of Charophyta, but its developmental role and the occurrence of PAT are unknown. We show that naphthylphthalamic acid (NPA)-sensitive PAT occurs in internodal cells of Chara corallina. The relatively high velocity (at least 4-5 cm/h) of auxin transport through the giant (3-5 cm) Chara cells does not occur by simple diffusion and is not sensitive to a specific cytoplasmic streaming inhibitor. The results demonstrate that PAT evolved early in multicellular plant life. The giant Chara cells provide a unique new model system to study PAT, as Chara allows the combining of real-time measurements and mathematical modelling with molecular, developmental, cellular, and electrophysiological studies.
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Affiliation(s)
- Kees J. M. Boot
- Plant Biodynamics Laboratory, Institute Biology Leiden, Leiden University, Sylviusweg 72, 2333 BE Leiden, The Netherlands
- Molecular and Developmental Genetics, Institute Biology Leiden, Leiden University, Sylviusweg 72, 2333 BE Leiden, The Netherlands
| | - Kees R. Libbenga
- Plant Biodynamics Laboratory, Institute Biology Leiden, Leiden University, Sylviusweg 72, 2333 BE Leiden, The Netherlands
| | - Sander C. Hille
- Plant Biodynamics Laboratory, Institute Biology Leiden, Leiden University, Sylviusweg 72, 2333 BE Leiden, The Netherlands
- Mathematical Institute, Leiden University, Niels Bohrweg 1, 2333 CA Leiden, The Netherlands
| | - Remko Offringa
- Plant Biodynamics Laboratory, Institute Biology Leiden, Leiden University, Sylviusweg 72, 2333 BE Leiden, The Netherlands
- Molecular and Developmental Genetics, Institute Biology Leiden, Leiden University, Sylviusweg 72, 2333 BE Leiden, The Netherlands
| | - Bert van Duijn
- Plant Biodynamics Laboratory, Institute Biology Leiden, Leiden University, Sylviusweg 72, 2333 BE Leiden, The Netherlands
- Fytagoras, Sylviusweg 72, 2333 BE Leiden, The Netherlands
- To whom correspondence should be addressed. E-mail:
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Hošek P, Kubeš M, Laňková M, Dobrev PI, Klíma P, Kohoutová M, Petrášek J, Hoyerová K, Jiřina M, Zažímalová E. Auxin transport at cellular level: new insights supported by mathematical modelling. JOURNAL OF EXPERIMENTAL BOTANY 2012; 63:3815-27. [PMID: 22438304 PMCID: PMC3388834 DOI: 10.1093/jxb/ers074] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2011] [Revised: 02/01/2012] [Accepted: 02/16/2012] [Indexed: 05/20/2023]
Abstract
The molecular basis of cellular auxin transport is still not fully understood. Although a number of carriers have been identified and proved to be involved in auxin transport, their regulation and possible activity of as yet unknown transporters remain unclear. Nevertheless, using single-cell-based systems it is possible to track the course of auxin accumulation inside cells and to specify and quantify some auxin transport parameters. The synthetic auxins 2,4-dichlorophenoxyacetic acid (2,4-D) and naphthalene-1-acetic acid (NAA) are generally considered to be suitable tools for auxin transport studies because they are transported specifically via either auxin influx or efflux carriers, respectively. Our results indicate that NAA can be metabolized rapidly in tobacco BY-2 cells. The predominant metabolite has been identified as NAA glucosyl ester and it is shown that all NAA metabolites were retained inside the cells. This implies that the transport efficiency of auxin efflux transporters is higher than previously assumed. By contrast, the metabolism of 2,4-D remained fairly weak. Moreover, using data on the accumulation of 2,4-D measured in the presence of auxin transport inhibitors, it is shown that 2,4-D is also transported by efflux carriers. These results suggest that 2,4-D is a promising tool for determining both auxin influx and efflux activities. Based on the accumulation data, a mathematical model of 2,4-D transport at a single-cell level is proposed. Optimization of the model provides estimates of crucial transport parameters and, together with its validation by successfully predicting the course of 2,4-D accumulation, it confirms the consistency of the present concept of cellular auxin transport.
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Affiliation(s)
- Petr Hošek
- Institute of Experimental Botany, the Academy of Sciences of the Czech Republic, Rozvojová 263, 165 02 Prague 6, Czech Republic
- Department of Biomedical Informatics, Faculty of Biomedical Engineering, Czech Technical University in Prague, Nám. Sítná 3105, 272 01 Kladno 2, Czech Republic
| | - Martin Kubeš
- Institute of Experimental Botany, the Academy of Sciences of the Czech Republic, Rozvojová 263, 165 02 Prague 6, Czech Republic
| | - Martina Laňková
- Institute of Experimental Botany, the Academy of Sciences of the Czech Republic, Rozvojová 263, 165 02 Prague 6, Czech Republic
| | - Petre I. Dobrev
- Institute of Experimental Botany, the Academy of Sciences of the Czech Republic, Rozvojová 263, 165 02 Prague 6, Czech Republic
| | - Petr Klíma
- Institute of Experimental Botany, the Academy of Sciences of the Czech Republic, Rozvojová 263, 165 02 Prague 6, Czech Republic
| | - Milada Kohoutová
- Department of Biomedical Informatics, Faculty of Biomedical Engineering, Czech Technical University in Prague, Nám. Sítná 3105, 272 01 Kladno 2, Czech Republic
| | - Jan Petrášek
- Institute of Experimental Botany, the Academy of Sciences of the Czech Republic, Rozvojová 263, 165 02 Prague 6, Czech Republic
| | - Klára Hoyerová
- Institute of Experimental Botany, the Academy of Sciences of the Czech Republic, Rozvojová 263, 165 02 Prague 6, Czech Republic
| | - Marcel Jiřina
- Department of Biomedical Informatics, Faculty of Biomedical Engineering, Czech Technical University in Prague, Nám. Sítná 3105, 272 01 Kladno 2, Czech Republic
| | - Eva Zažímalová
- Institute of Experimental Botany, the Academy of Sciences of the Czech Republic, Rozvojová 263, 165 02 Prague 6, Czech Republic
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Kubeš M, Yang H, Richter GL, Cheng Y, Młodzińska E, Wang X, Blakeslee JJ, Carraro N, Petrášek J, Zažímalová E, Hoyerová K, Peer WA, Murphy AS. The Arabidopsis concentration-dependent influx/efflux transporter ABCB4 regulates cellular auxin levels in the root epidermis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2012; 69:640-54. [PMID: 21992190 DOI: 10.1111/j.1365-313x.2011.04818.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Arabidopsis ATP-binding cassette B4 (ABCB4) is a root-localised auxin efflux transporter with reported auxin uptake activity in low auxin concentrations. Results reported here demonstrate that ABCB4 is a substrate-activated regulator of cellular auxin levels. The contribution of ABCB4 to shootward auxin movement at the root apex increases with auxin concentration, but in root hair elongation assays ABCB4-mediated uptake is evident at low concentrations as well. Uptake kinetics of ABCB4 heterologously expressed in Schizosaccharomyces pombe differed from the saturation kinetics of AUX1 as uptake converted to efflux at threshold indole-3-acetic acid (IAA) concentrations. The concentration dependence of ABCB4 appears to be a direct effect on transporter activity, as ABCB4 expression and ABCB4 plasma membrane (PM) localisation at the root apex are relatively insensitive to changes in auxin concentration. However, PM localization of ABCB4 decreases with 1-naphthylphthalamic acid (NPA) treatment. Unlike other plant ABCBs studied to date, and consistent with decreased detergent solubility, ABCB4(pro) :ABCB4-GFP is partially internalised in all cell types by 0.05% DMSO, but not 0.1% ethanol. In trichoblasts, ABCB4(pro) :ABCB4-GFP PM signals are reduced by >200 nm IAA and 2,4-dichlorophenoxyacetic acid (2,4-D). In heterologous systems and in planta, ABCB4 transports benzoic acid with weak affinity, but not the oxidative catabolism products 2-oxindole-3-acetic-acid and 2-oxindole-3-acetyl-β-D-glucose. ABCB4 mediates uptake, but not efflux, of the synthetic auxin 2,4-D in cells lacking AUX1 activity. Results presented here suggest that 2,4-D is a non-competitive inhibitor of IAA transport by ABCB4 and indicate that ABCB4 is a target of 2,4-D herbicidal activity.
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Affiliation(s)
- Martin Kubeš
- Institute of Experimental Botany, the Academy of Sciences of the Czech Republic, Rozvojová 263, CZ-165 02 Prague 6, Czech Republic
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Swarup R, Péret B. AUX/LAX family of auxin influx carriers-an overview. FRONTIERS IN PLANT SCIENCE 2012; 3:225. [PMID: 23087694 PMCID: PMC3475149 DOI: 10.3389/fpls.2012.00225] [Citation(s) in RCA: 187] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2012] [Accepted: 09/20/2012] [Indexed: 05/19/2023]
Abstract
Auxin regulates several aspects of plant growth and development. Auxin is unique among plant hormones for exhibiting polar transport. Indole-3-acetic acid (IAA), the major form of auxin in higher plants, is a weak acid and its intercellular movement is facilitated by auxin influx and efflux carriers. Polarity of auxin movement is provided by asymmetric localization of auxin carriers (mainly PIN efflux carriers). PIN-FORMED (PIN) and P-GLYCOPROTEIN (PGP) family of proteins are major auxin efflux carriers whereas AUXIN1/LIKE-AUX1 (AUX/LAX) are major auxin influx carriers. Genetic and biochemical evidence show that each member of the AUX/LAX family is a functional auxin influx carrier and mediate auxin related developmental programmes in different organs and tissues. Of the four AUX/LAX genes, AUX1 regulates root gravitropism, root hair development and leaf phyllotaxy whereas LAX2 regulates vascular development in cotyledons. Both AUX1 and LAX3 have been implicated in lateral root (LR) development as well as apical hook formation whereas both AUX1 and LAX1 and possibly LAX2 are required for leaf phyllotactic patterning.
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Affiliation(s)
- Ranjan Swarup
- School of Biosciences and Centre for Plant Integrative Biology, University of NottinghamLoughborough, UK
- *Correspondence: Ranjan Swarup, School of Biosciences and Centre for Plant Integrative Biology, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, UK. e-mail:
| | - Benjamin Péret
- Laboratory of Plant Development Biology, SBVME/Institute for Biotechnology and Environmental Biology, CEA CadaracheSt. Paul lez Durance, France
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