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Vivo-Llorca G, Morellá-Aucejo Á, García-Fernández A, Díez P, Llopis-Lorente A, Orzáez M, Martínez-Máñez R. Horseradish Peroxidase-Functionalized Gold Nanoconjugates for Breast Cancer Treatment Based on Enzyme Prodrug Therapy. Int J Nanomedicine 2022; 17:409-422. [PMID: 35115775 PMCID: PMC8802903 DOI: 10.2147/ijn.s323802] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 10/28/2021] [Indexed: 01/13/2023] Open
Abstract
Introduction Breast cancer has the highest mortality rate among cancers in women. Patients suffering from certain breast cancers, such as triple-negative breast cancer (TNBC), lack effective treatments. This represents a clinical concern due to the associated poor prognosis and high mortality. As an approach to succeed over conventional therapy limitations, we present herein the design and evaluation of a novel nanodevice based on enzyme-functionalized gold nanoparticles to efficiently perform enzyme prodrug therapy (EPT) in breast cancer cells. Results In particular, the enzyme horseradish peroxidase (HRP) – which oxidizes the prodrug indole-3-acetic acid (IAA) to release toxic oxidative species – is incorporated on gold nanoconjugates (HRP-AuNCs), obtaining an efficient nanoplatform for EPT. The nanodevice is biocompatible and effectively internalized by breast cancer cell lines. Remarkably, co-treatment with HRP-AuNCs and IAA (HRP-AuNCs/IAA) reduces the viability of breast cancer cells below 5%. Interestingly, 3D tumor models (multicellular tumor spheroid-like cultures) co-treated with HRP-AuNCs/IAA exhibit a 74% reduction of cell viability, whereas the free formulated components (HRP, IAA) have no effect. Conclusion Altogether, our results demonstrate that the designed HRP-AuNCs nanoformulation shows a remarkable therapeutic performance. These findings might help to bypass the clinical limitations of current tumor enzyme therapies and advance towards the use of nanoformulations for EPT in breast cancer.
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Affiliation(s)
- Gema Vivo-Llorca
- Instituto Interuniversitario de Investigación de Reconocimiento Molecular y Desarrollo Tecnológico (IDM), Universitat Politècnica de València, Universitat de València, València, Spain
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Madrid, Spain
- Unidad Mixta UPV-CIPF de Investigación de Mecanismos de Enfermedades y Nanomedicina, Valencia, Universitat Politècnica de València, Centro de Investigación Príncipe Felipe, València, Spain
| | - Ángela Morellá-Aucejo
- Instituto Interuniversitario de Investigación de Reconocimiento Molecular y Desarrollo Tecnológico (IDM), Universitat Politècnica de València, Universitat de València, València, Spain
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Madrid, Spain
- Unidad Mixta UPV-CIPF de Investigación de Mecanismos de Enfermedades y Nanomedicina, Valencia, Universitat Politècnica de València, Centro de Investigación Príncipe Felipe, València, Spain
| | - Alba García-Fernández
- Instituto Interuniversitario de Investigación de Reconocimiento Molecular y Desarrollo Tecnológico (IDM), Universitat Politècnica de València, Universitat de València, València, Spain
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Madrid, Spain
- Unidad Mixta UPV-CIPF de Investigación de Mecanismos de Enfermedades y Nanomedicina, Valencia, Universitat Politècnica de València, Centro de Investigación Príncipe Felipe, València, Spain
- Correspondence: Alba García-Fernández; Ramón Martínez-Máñez Email ;
| | - Paula Díez
- Instituto Interuniversitario de Investigación de Reconocimiento Molecular y Desarrollo Tecnológico (IDM), Universitat Politècnica de València, Universitat de València, València, Spain
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Madrid, Spain
- Unidad Mixta UPV-CIPF de Investigación de Mecanismos de Enfermedades y Nanomedicina, Valencia, Universitat Politècnica de València, Centro de Investigación Príncipe Felipe, València, Spain
- Unidad Mixta de Investigación en Nanomedicina y sensores, Universitat Politènica de València, Instituto de Investigación Sanitaria la Fe, Valènica, Spain
| | - Antoni Llopis-Lorente
- Instituto Interuniversitario de Investigación de Reconocimiento Molecular y Desarrollo Tecnológico (IDM), Universitat Politècnica de València, Universitat de València, València, Spain
- Department of Chemical Engineering and Chemistry, Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Mar Orzáez
- Unidad Mixta UPV-CIPF de Investigación de Mecanismos de Enfermedades y Nanomedicina, Valencia, Universitat Politècnica de València, Centro de Investigación Príncipe Felipe, València, Spain
- Centro de Investigación Príncipe Felipe, Laboratorio de Péptidos y Proteínas, València, Spain
| | - Ramón Martínez-Máñez
- Instituto Interuniversitario de Investigación de Reconocimiento Molecular y Desarrollo Tecnológico (IDM), Universitat Politècnica de València, Universitat de València, València, Spain
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Madrid, Spain
- Unidad Mixta UPV-CIPF de Investigación de Mecanismos de Enfermedades y Nanomedicina, Valencia, Universitat Politècnica de València, Centro de Investigación Príncipe Felipe, València, Spain
- Unidad Mixta de Investigación en Nanomedicina y sensores, Universitat Politènica de València, Instituto de Investigación Sanitaria la Fe, Valènica, Spain
- Departamento de Química, Universitat Politècnica de València, València, Spain
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Harnvanichvech Y, Gorelova V, Sprakel J, Weijers D. The Arabidopsis embryo as a quantifiable model for studying pattern formation. QUANTITATIVE PLANT BIOLOGY 2021; 2:e3. [PMID: 37077211 PMCID: PMC10095805 DOI: 10.1017/qpb.2021.3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 02/15/2021] [Accepted: 02/21/2021] [Indexed: 05/03/2023]
Abstract
Phenotypic diversity of flowering plants stems from common basic features of the plant body pattern with well-defined body axes, organs and tissue organisation. Cell division and cell specification are the two processes that underlie the formation of a body pattern. As plant cells are encased into their cellulosic walls, directional cell division through precise positioning of division plane is crucial for shaping plant morphology. Since many plant cells are pluripotent, their fate establishment is influenced by their cellular environment through cell-to-cell signaling. Recent studies show that apart from biochemical regulation, these two processes are also influenced by cell and tissue morphology and operate under mechanical control. Finding a proper model system that allows dissecting the relationship between these aspects is the key to our understanding of pattern establishment. In this review, we present the Arabidopsis embryo as a simple, yet comprehensive model of pattern formation compatible with high-throughput quantitative assays.
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Affiliation(s)
- Yosapol Harnvanichvech
- Physical Chemistry and Soft Matter, Wageningen University, Wageningen, The Netherlands
- Laboratory of Biochemistry, Wageningen University, Wageningen, The Netherlands
| | - Vera Gorelova
- Laboratory of Biochemistry, Wageningen University, Wageningen, The Netherlands
| | - Joris Sprakel
- Physical Chemistry and Soft Matter, Wageningen University, Wageningen, The Netherlands
| | - Dolf Weijers
- Laboratory of Biochemistry, Wageningen University, Wageningen, The Netherlands
- Author for correspondence: Dolf Weijers, E-mail:
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3
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Javed Z, Tripathi GD, Mishra M, Dashora K. Actinomycetes – The microbial machinery for the organic-cycling, plant growth, and sustainable soil health. BIOCATALYSIS AND AGRICULTURAL BIOTECHNOLOGY 2021. [DOI: 10.1016/j.bcab.2020.101893] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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4
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Yue J, Yang H, Yang S, Wang J. TDIF regulates auxin accumulation and modulates auxin sensitivity to enhance both adventitious root and lateral root formation in poplar trees. TREE PHYSIOLOGY 2020; 40:1534-1547. [PMID: 32598454 DOI: 10.1093/treephys/tpaa077] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 05/11/2020] [Accepted: 06/16/2020] [Indexed: 05/25/2023]
Abstract
Of six TRACHEARY ELEMENT DIFFERENTIATION INHIBITORY FACTOR (TDIF)-encoding genes in poplar, PtTDIF1 is predominantly expressed in adventitious roots (ARs), and the other five PtTDIFs are preferentially expressed in lateral roots (LRs). Upon auxin application, expression of all PtTDIFs declined in ARs but transiently increased in LRs. Both exogenous TDIF peptides and overexpression of PtTDIFs in poplar positively regulated the initiation and elongation of LRs, and overexpression of PtTDIFs also increased the number of ARs. As visualized by the auxin-responsive marker DR5:GUS, TDIF had differential impacts on the auxin signaling activity in ARs and LRs, which was corroborated by the free indole-3-acetic acid (IAA) measurements in them. Shoot tips of PtTDIF2- and PtTDIFL2-overexpressing (together as PtTDIFsOE) trees revealed an enhanced IAA biosynthetic capacity, and removal of the aerial tissues dramatically diminished the root phenotypes of micro-propagated PtTDIFsOE trees. Furthermore, PtTDIFsOE poplars displayed an increased sensitivity for exogenous IAA, and N-1-naphthylphthalamic acid (NPA) completely blocked the TDIF-induced AR and LR formation. In PtTDIFsOE roots, several auxin-related LR initiation markers such as GATA23, LBD16 and LBD29 were transcriptionally upregulated, further supporting that TDIF regulates LR organogenesis by strengthening the spatiotemporal auxin cues and that dynamic interplays between hormones govern root branching and developmental plasticity in tree species.
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Affiliation(s)
- Jing Yue
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Heyu Yang
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Shaohui Yang
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Jiehua Wang
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
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5
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Dong W, Song Y. The Significance of Flavonoids in the Process of Biological Nitrogen Fixation. Int J Mol Sci 2020; 21:E5926. [PMID: 32824698 PMCID: PMC7460597 DOI: 10.3390/ijms21165926] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 08/12/2020] [Accepted: 08/14/2020] [Indexed: 11/16/2022] Open
Abstract
Nitrogen is essential for the growth of plants. The ability of some plant species to obtain all or part of their requirement for nitrogen by interacting with microbial symbionts has conferred a major competitive advantage over those plants unable to do so. The function of certain flavonoids (a group of secondary metabolites produced by the plant phenylpropanoid pathway) within the process of biological nitrogen fixation carried out by Rhizobium spp. has been thoroughly researched. However, their significance to biological nitrogen fixation carried out during the actinorhizal and arbuscular mycorrhiza-Rhizobium-legume interaction remains unclear. This review catalogs and contextualizes the role of flavonoids in the three major types of root endosymbiosis responsible for biological nitrogen fixation. The importance of gaining an understanding of the molecular basis of endosymbiosis signaling, as well as the potential of and challenges facing modifying flavonoids either quantitatively and/or qualitatively are discussed, along with proposed strategies for both optimizing the process of nodulation and widening the plant species base, which can support nodulation.
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Affiliation(s)
| | - Yuguang Song
- School of Life Science, Qufu Normal University, Qufu 273165, China;
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6
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Singh S, Yadav S, Singh A, Mahima M, Singh A, Gautam V, Sarkar AK. Auxin signaling modulates LATERAL ROOT PRIMORDIUM1 (LRP1) expression during lateral root development in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 101:87-100. [PMID: 31483536 DOI: 10.1111/tpj.14520] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 08/17/2019] [Accepted: 08/21/2019] [Indexed: 05/18/2023]
Abstract
Auxin signaling mediated by various auxin/indole-3-acetic acid (Aux/IAAs) and AUXIN RESPONSE FACTORs (ARFs) regulate lateral root (LR) development by controlling the expression of downstream genes. LATERAL ROOT PRIMORDIUM1 (LRP1), a member of the SHORT INTERNODES/STYLISH (SHI/STY) family, was identified as an auxin-inducible gene. The precise developmental role and molecular regulation of LRP1 in root development remain to be understood. Here we show that LRP1 is expressed in all stages of LR development, besides the primary root. The expression of LRP1 is regulated by histone deacetylation in an auxin-dependent manner. Our genetic interaction studies showed that LRP1 acts downstream of auxin responsive Aux/IAAs-ARFs modules during LR development. We showed that auxin-mediated induction of LRP1 is lost in emerging LRs of slr-1 and arf7arf19 mutants roots. NPA treatment studies showed that LRP1 acts after LR founder cell specification and asymmetric division during LR development. Overexpression of LRP1 (LRP1 OE) showed an increased number of LR primordia (LRP) at stages I, IV and V, resulting in reduced emerged LR density, which suggests that it is involved in LRP development. Interestingly, LRP1-induced expression of YUC4, which is involved in auxin biosynthesis, contributes to the increased accumulation of endogenous auxin in LRP1 OE roots. LRP1 interacts with SHI, STY1, SRS3, SRS6 and SRS7 proteins of the SHI/STY family, indicating their possible redundant role during root development. Our results suggested that auxin and histone deacetylation affect LRP1 expression and it acts downstream of LR forming auxin response modules to negatively regulate LRP development by modulating auxin homeostasis in Arabidopsis thaliana.
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Affiliation(s)
- Sharmila Singh
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Sandeep Yadav
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Alka Singh
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Mahima Mahima
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Archita Singh
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Vibhav Gautam
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India
- Centre of Experimental Medicine and Surgery, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
| | - Ananda K Sarkar
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India
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7
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Meents AK, Furch ACU, Almeida-Trapp M, Özyürek S, Scholz SS, Kirbis A, Lenser T, Theißen G, Grabe V, Hansson B, Mithöfer A, Oelmüller R. Beneficial and Pathogenic Arabidopsis Root-Interacting Fungi Differently Affect Auxin Levels and Responsive Genes During Early Infection. Front Microbiol 2019; 10:380. [PMID: 30915043 PMCID: PMC6422953 DOI: 10.3389/fmicb.2019.00380] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Accepted: 02/13/2019] [Indexed: 01/08/2023] Open
Abstract
Auxin (indole-3-acetic acid, IAA) is an important phytohormone involved in root growth and development. Root-interacting beneficial and pathogenic fungi utilize auxin and its target genes to manipulate the performance of their hosts for their own needs. In order to follow and visualize auxin effects in fungi-colonized Arabidopsis roots, we used the dual auxin reporter construct DR5::EGFP-DR5v2::tdTomato and fluorescence microscopy as well as LC-MS-based phytohormone analyses. We demonstrate that the beneficial endophytic fungi Piriformospora indica and Mortierella hyalina produce and accumulate IAA in their mycelia, in contrast to the phytopathogenic biotrophic fungus Verticillium dahliae and the necrotrophic fungus Alternaria brassicicola. Within 3 h after exposure of Arabidopsis roots to the pathogens, the signals of the auxin-responsive reporter genes disappeared. When exposed to P. indica, significantly higher auxin levels and stimulated expression of auxin-responsive reporter genes were detected both in lateral root primordia and the root elongation zone within 1 day. Elevated auxin levels were also present in the M. hyalina/Arabidopsis root interaction, but no downstream effects on auxin-responsive reporter genes were observed. However, the jasmonate level was strongly increased in the colonized roots. We propose that the lack of stimulated root growth upon infection with M. hyalina is not caused by the absence of auxin, but an inhibitory effect mediated by high jasmonate content.
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Affiliation(s)
- Anja K Meents
- Department of Bioorganic Chemistry, Max Planck Institute for Chemical Ecology, Jena, Germany.,Department of Plant Physiology, Matthias Schleiden Institute of Genetics, Bioinformatics and Molecular Botany, Friedrich-Schiller-University Jena, Jena, Germany.,Research Group Plant Defense Physiology, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Alexandra C U Furch
- Department of Plant Physiology, Matthias Schleiden Institute of Genetics, Bioinformatics and Molecular Botany, Friedrich-Schiller-University Jena, Jena, Germany
| | - Marília Almeida-Trapp
- Department of Bioorganic Chemistry, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Sedef Özyürek
- Department of Plant Physiology, Matthias Schleiden Institute of Genetics, Bioinformatics and Molecular Botany, Friedrich-Schiller-University Jena, Jena, Germany
| | - Sandra S Scholz
- Department of Plant Physiology, Matthias Schleiden Institute of Genetics, Bioinformatics and Molecular Botany, Friedrich-Schiller-University Jena, Jena, Germany
| | - Alexander Kirbis
- Department of Genetics, Matthias Schleiden Institute of Genetics, Bioinformatics and Molecular Botany, Friedrich-Schiller-University Jena, Jena, Germany
| | - Teresa Lenser
- Department of Genetics, Matthias Schleiden Institute of Genetics, Bioinformatics and Molecular Botany, Friedrich-Schiller-University Jena, Jena, Germany
| | - Günter Theißen
- Department of Genetics, Matthias Schleiden Institute of Genetics, Bioinformatics and Molecular Botany, Friedrich-Schiller-University Jena, Jena, Germany
| | - Veit Grabe
- Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Bill Hansson
- Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Axel Mithöfer
- Department of Bioorganic Chemistry, Max Planck Institute for Chemical Ecology, Jena, Germany.,Research Group Plant Defense Physiology, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Ralf Oelmüller
- Department of Plant Physiology, Matthias Schleiden Institute of Genetics, Bioinformatics and Molecular Botany, Friedrich-Schiller-University Jena, Jena, Germany
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Pulungan SI, Yano R, Okabe Y, Ichino T, Kojima M, Takebayashi Y, Sakakibara H, Ariizumi T, Ezura H. SlLAX1 is Required for Normal Leaf Development Mediated by Balanced Adaxial and Abaxial Pavement Cell Growth in Tomato. PLANT & CELL PHYSIOLOGY 2018. [PMID: 29528453 DOI: 10.1093/pcp/pcy052] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Leaves are the major plant organs with a primary function for photosynthesis. Auxin controls various aspects of plant growth and development, including leaf initiation, expansion and differentiation. Unique and intriguing auxin features include its polar transport, which is mainly controlled by the AUX1/LAX and PIN gene families as influx and efflux carriers, respectively. The role of AUX1/LAX genes in root development is well documented, but the role of these genes in leaf morphogenesis remains unclear. Moreover, most studies have been conducted in the plant model Arabidopsis thaliana, while studies in tomato are still scarce. In this study, we isolated six lines of the allelic curly leaf phenotype 'curl' mutants from a γ-ray and EMS (ethyl methanesulfonate) mutagenized population. Using a map-based cloning strategy combined with exome sequencing, we observed that a mutation occurred in the SlLAX1 gene (Solyc09g014380), which is homologous to an Arabidopsis auxin influx carrier gene, AUX1 (AtAUX1). Characterization of six alleles of single curl mutants revealed the pivotal role of SlLAX1 in controlling tomato leaf flatness by balancing adaxial and abaxial pavement cell growth, which has not been reported in tomato. Using TILLING (Targeting Induced Local Lesions IN Genome) technology, we isolated an additional mutant allele of the SlLAX1 gene and this mutant showed a curled leaf phenotype similar to other curl mutants, suggesting that Solyc09g014380 is responsible for the curl phenotype. These results showed that SlLAX1 is required for normal leaf development mediated by balanced adaxial and abaxial pavement cell growth in tomato.
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Affiliation(s)
- Sri Imriani Pulungan
- Graduate School Life and Environmental Sciences, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki, 305-8572 Japan
| | - Ryoichi Yano
- Faculty Life and Environmental Sciences, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki, 305-8572 Japan
| | - Yoshihiro Okabe
- Faculty Life and Environmental Sciences, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki, 305-8572 Japan
- Tsukuba Plant Innovation Research Center, University of Tsukuba, Tsukuba, Ibaraki, 305-8577 Japan
| | - Takuji Ichino
- Faculty Life and Environmental Sciences, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki, 305-8572 Japan
| | - Mikiko Kojima
- RIKEN Center for Sustainable Resource Science, Suehiro 1-7-22, Tsurumi, Yokohama, Kanagawa, 230-0045 Japan
| | - Yumiko Takebayashi
- RIKEN Center for Sustainable Resource Science, Suehiro 1-7-22, Tsurumi, Yokohama, Kanagawa, 230-0045 Japan
| | - Hitoshi Sakakibara
- RIKEN Center for Sustainable Resource Science, Suehiro 1-7-22, Tsurumi, Yokohama, Kanagawa, 230-0045 Japan
| | - Tohru Ariizumi
- Faculty Life and Environmental Sciences, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki, 305-8572 Japan
- Tsukuba Plant Innovation Research Center, University of Tsukuba, Tsukuba, Ibaraki, 305-8577 Japan
| | - Hiroshi Ezura
- Faculty Life and Environmental Sciences, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki, 305-8572 Japan
- Tsukuba Plant Innovation Research Center, University of Tsukuba, Tsukuba, Ibaraki, 305-8577 Japan
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AUX1-mediated root hair auxin influx governs SCF TIR1/AFB-type Ca 2+ signaling. Nat Commun 2018; 9:1174. [PMID: 29563504 PMCID: PMC5862985 DOI: 10.1038/s41467-018-03582-5] [Citation(s) in RCA: 120] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 02/26/2018] [Indexed: 01/01/2023] Open
Abstract
Auxin is a key regulator of plant growth and development, but the causal relationship between hormone transport and root responses remains unresolved. Here we describe auxin uptake, together with early steps in signaling, in Arabidopsis root hairs. Using intracellular microelectrodes we show membrane depolarization, in response to IAA in a concentration- and pH-dependent manner. This depolarization is strongly impaired in aux1 mutants, indicating that AUX1 is the major transporter for auxin uptake in root hairs. Local intracellular auxin application triggers Ca2+ signals that propagate as long-distance waves between root cells and modulate their auxin responses. AUX1-mediated IAA transport, as well as IAA- triggered calcium signals, are blocked by treatment with the SCFTIR1/AFB - inhibitor auxinole. Further, they are strongly reduced in the tir1afb2afb3 and the cngc14 mutant. Our study reveals that the AUX1 transporter, the SCFTIR1/AFB receptor and the CNGC14 Ca2+ channel, mediate fast auxin signaling in roots. Auxin regulates multiple aspects of plant growth and development. Here Dindas et al. show that in root-hair cells, the AUX1 auxin influx carrier mediates proton-driven auxin import that is perceived by auxin receptors and coupled to Ca2+ waves that may modulate adaptive responses in the root.
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10
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Actinomycetes benefaction role in soil and plant health. Microb Pathog 2017; 111:458-467. [DOI: 10.1016/j.micpath.2017.09.036] [Citation(s) in RCA: 176] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2017] [Revised: 09/13/2017] [Accepted: 09/14/2017] [Indexed: 11/18/2022]
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11
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Ng JLP, Perrine-Walker F, Wasson AP, Mathesius U. The Control of Auxin Transport in Parasitic and Symbiotic Root-Microbe Interactions. PLANTS (BASEL, SWITZERLAND) 2015; 4:606-43. [PMID: 27135343 PMCID: PMC4844411 DOI: 10.3390/plants4030606] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Revised: 08/12/2015] [Accepted: 08/18/2015] [Indexed: 01/13/2023]
Abstract
Most field-grown plants are surrounded by microbes, especially from the soil. Some of these, including bacteria, fungi and nematodes, specifically manipulate the growth and development of their plant hosts, primarily for the formation of structures housing the microbes in roots. These developmental processes require the correct localization of the phytohormone auxin, which is involved in the control of cell division, cell enlargement, organ development and defense, and is thus a likely target for microbes that infect and invade plants. Some microbes have the ability to directly synthesize auxin. Others produce specific signals that indirectly alter the accumulation of auxin in the plant by altering auxin transport. This review highlights root-microbe interactions in which auxin transport is known to be targeted by symbionts and parasites to manipulate the development of their host root system. We include case studies for parasitic root-nematode interactions, mycorrhizal symbioses as well as nitrogen fixing symbioses in actinorhizal and legume hosts. The mechanisms to achieve auxin transport control that have been studied in model organisms include the induction of plant flavonoids that indirectly alter auxin transport and the direct targeting of auxin transporters by nematode effectors. In most cases, detailed mechanisms of auxin transport control remain unknown.
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Affiliation(s)
- Jason Liang Pin Ng
- Division of Plant Science, Research School of Biology, Australian National University, Linnaeus Way, Building 134, Canberra ACT 2601, Australia.
| | | | | | - Ulrike Mathesius
- Division of Plant Science, Research School of Biology, Australian National University, Linnaeus Way, Building 134, Canberra ACT 2601, Australia.
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Chandler JW, Werr W. Cytokinin-auxin crosstalk in cell type specification. TRENDS IN PLANT SCIENCE 2015; 20:291-300. [PMID: 25805047 DOI: 10.1016/j.tplants.2015.02.003] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Revised: 02/13/2015] [Accepted: 02/24/2015] [Indexed: 05/24/2023]
Abstract
Auxin and cytokinin affect cell fate specification transcriptionally and non-transcriptionally, and their roles have been characterised in several founder cell specification and activation contexts. Similarly to auxin, local cytokinin synthesis and response gradients are instructive, and the roles of ARABIDOPSIS RESPONSE REGULATOR 7/15 (ARR7/15) and the negative cytokinin response regulator ARABIDOPSIS HISTIDINE PHOSPHOTRANSFER PROTEIN 6, as well as auxin signalling via MONOPTEROS/BODENLOS, are functionally conserved across different developmental processes. Auxin and cytokinin crosstalk is tissue- and context-specific, and may be synergistic in the shoot apical meristem (SAM) but antagonistic in the root. We review recent advances in understanding the interactions between auxin and cytokinin in pivotal developmental processes, and show that feedback complexity and the multistep nature of specification processes argue against a single morphogenetic signal.
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Affiliation(s)
- John William Chandler
- Institute of Developmental Biology, Cologne Biocenter, Zülpicher Strasse 47b, 50674 Cologne, Germany.
| | - Wolfgang Werr
- Institute of Developmental Biology, Cologne Biocenter, Zülpicher Strasse 47b, 50674 Cologne, Germany
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Revalska M, Vassileva V, Zechirov G, Iantcheva A. Is the auxin influx carrierLAX3essential for plant growth and development in the model plantsMedicago truncatula, Lotus japonicusandArabidopsis thaliana? BIOTECHNOL BIOTEC EQ 2015. [DOI: 10.1080/13102818.2015.1031698] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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14
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Pabón-Mora N, Sharma B, Holappa LD, Kramer EM, Litt A. The Aquilegia FRUITFULL-like genes play key roles in leaf morphogenesis and inflorescence development. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 74:197-212. [PMID: 23294330 DOI: 10.1111/tpj.12113] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Revised: 12/19/2012] [Accepted: 01/02/2013] [Indexed: 05/03/2023]
Abstract
The APETALA1/FRUITFULL (AP1/FUL) MADS box transcription factors are best known for the role of AP1 in Arabidopsis sepal and petal identity, the canonical A function of the ABC model of flower development. However, this gene lineage underwent multiple duplication events during angiosperm evolution, providing different taxa with unique gene complements. One such duplication correlates with the origin of the core eudicots, and produced the euAP1 and euFUL clades. Together, euAP1 and euFUL genes function in proper floral meristem identity and repression of axillary meristem growth. Independently, euAP1 genes function in floral meristem and sepal identity, whereas euFUL genes control phase transition, cauline leaf growth and fruit development. To investigate the impact of the core eudicot duplication on the functional diversification of this gene lineage, we studied the role of pre-duplication FUL-like genes in columbine (Aquilegia coerulea). Our results show that AqcFL1 genes are broadly expressed in vegetative and reproductive meristems, leaves and flowers. Virus-induced gene silencing of the loci results in plants with increased branching, shorter inflorescences with fewer flowers, and dramatic changes in leaf shape and complexity. However, aqcfl1 plants have normal flowers and fruits. Our results show that, in contrast to characterized AP1/FUL genes, the AqcFL1 loci are either genetically redundant or have been decoupled from the floral genetic program, and play a major role in leaf morphogenesis. We analyze the results in the context of the core eudicot duplication, and discuss the implications of our findings in terms of the genetic regulation of leaf morphogenesis in Aquilegia and other flowering plants.
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1,10-Phenanthroline promotes copper complexes into tumor cells and induces apoptosis by inhibiting the proteasome activity. J Biol Inorg Chem 2012; 17:1257-67. [PMID: 23053530 DOI: 10.1007/s00775-012-0940-x] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Accepted: 09/12/2012] [Indexed: 01/09/2023]
Abstract
Indole-3-acetic acid and indole-3-propionic acid, two potent natural plant growth hormones, have attracted attention as promising prodrugs in cancer therapy. Copper is known to be a cofactor essential for tumor angiogenesis. We have previously reported that taurine, L-glutamine, and quinoline-2-carboxaldehyde Schiff base copper complexes inhibit cell proliferation and proteasome activity in human cancer cells. In the current study, we synthesized two types of copper complexes, dinuclear complexes and ternary complexes, to investigate whether a certain structure could easily carry copper into cancer cells and consequently inhibit tumor proteasome activity and induce apoptosis. We observed that ternary complexes binding with 1,10-phenanthroline are more potent proteasome inhibitors and apoptosis inducers than dinuclear complexes in PC-3 human prostate cancer cells. Furthermore, the ternary complexes potently inhibit proteasome activity before induction of apoptosis in MDA-MB-231 human breast cancer cells, but not in nontumorigenic MCF-10A cells. Our results suggest that copper complexes binding with 1,10-phenanthroline as the third ligand could serve as potent, selective proteasome inhibitors and apoptosis inducers in tumor cells, and that the ternary complexes may be good potential anticancer drugs.
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Abdel-Lateif K, Bogusz D, Hocher V. The role of flavonoids in the establishment of plant roots endosymbioses with arbuscular mycorrhiza fungi, rhizobia and Frankia bacteria. PLANT SIGNALING & BEHAVIOR 2012; 7:636-41. [PMID: 22580697 PMCID: PMC3442858 DOI: 10.4161/psb.20039] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Flavonoids are a group of secondary metabolites derived from the phenylpropanoid pathway. They are ubiquitous in the plant kingdom and have many diverse functions including key roles at different levels of root endosymbioses. While there is a lot of information on the role of particular flavonoids in the Rhizobium-legume symbiosis, yet their exact role during the establishment of arbuscular mycorrhiza and actinorhizal symbioses still remains unclear. Within the context of the latest data suggesting a common symbiotic signaling pathway for both plant-fungal and plant bacterial endosymbioses between legumes and actinorhiza-forming fagales, this mini-review highlights some of the recent studies on the three major types of root endosymbioses. Implication of the molecular knowledge of endosymbioses signaling and genetic manipulation of flavonoid biosynthetic pathway on the development of strategies for the transfer and optimization of nodulation are also discussed.
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Affiliation(s)
- Khalid Abdel-Lateif
- Equipe Rhizogenèse; UMR DIADE (IRD, UM2); Institut de Recherche pour le Développement (IRD); Montpellier, France
| | - Didier Bogusz
- Equipe Rhizogenèse; UMR DIADE (IRD, UM2); Institut de Recherche pour le Développement (IRD); Montpellier, France
| | - Valérie Hocher
- Equipe Rhizogenèse; UMR DIADE (IRD, UM2); Institut de Recherche pour le Développement (IRD); Montpellier, France
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Kharshiing EV, Kumar GP, Sharma R. PIN it on auxin: the role of PIN1 and PAT in tomato development. PLANT SIGNALING & BEHAVIOR 2010; 5:1379-83. [PMID: 20980815 PMCID: PMC3115237 DOI: 10.4161/psb.5.11.13035] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Accepted: 07/16/2010] [Indexed: 05/23/2023]
Abstract
The growth and development of plants is regulated by several external and internal factors including auxin. Its distribution regulates several developmental processes in plants. Auxin molecules function as mobile signals and are involved in the spatial and temporal coordination of plant morphogenesis and in plant responses to their environment. The intercellular transport of auxin is facilitated by transport proteins and the disruption of polar auxin flow results in various developmental abnormalities. In this review, we discuss the developmental and physiological significance of over-accumulation of PIN1 auxin transport facilitator protein in tomato as seen in the enhanced polar auxin transport pct1-2 mutant.
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Affiliation(s)
- Eros V Kharshiing
- Department of Botany; St. Edmund's College; Meghalaya, India
- School of Life Sciences; University of Hyderabad; Hyderabad, India
| | - G Pavan Kumar
- School of Life Sciences; University of Hyderabad; Hyderabad, India
| | - Rameshwar Sharma
- School of Life Sciences; University of Hyderabad; Hyderabad, India
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Zazímalová E, Murphy AS, Yang H, Hoyerová K, Hosek P. Auxin transporters--why so many? Cold Spring Harb Perspect Biol 2010; 2:a001552. [PMID: 20300209 PMCID: PMC2829953 DOI: 10.1101/cshperspect.a001552] [Citation(s) in RCA: 253] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Interacting and coordinated auxin transporter actions in plants underlie a flexible network that mobilizes auxin in response to many developmental and environmental changes encountered by these sessile organisms. The independent but synergistic activity of individual transporters can be differentially regulated at various levels. This invests auxin transport mechanisms with robust functional redundancy and added auxin flow capacity when needed. An evolutionary perspective clarifies the roles of the different transporter groups in plant development. Mathematical and functional analysis of elements of auxin transport makes it possible to rationalize the relative contributions of members of the respective transporter classes to the localized auxin transport streams that then underlie both preprogrammed developmental changes and reactions to environmental stimuli.
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Affiliation(s)
- Eva Zazímalová
- Institute of Experimental Botany AS CR, Rozvojová 263, CZ-165 02 Prague 6, Czech Republic.
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Flachowsky H, Szankowski I, Fischer TC, Richter K, Peil A, Höfer M, Dörschel C, Schmoock S, Gau AE, Halbwirth H, Hanke MV. Transgenic apple plants overexpressing the Lc gene of maize show an altered growth habit and increased resistance to apple scab and fire blight. PLANTA 2010; 231:623-35. [PMID: 19967387 DOI: 10.1007/s00425-009-1074-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2009] [Accepted: 11/10/2009] [Indexed: 05/07/2023]
Abstract
Transgenic apple plants (Malus x domestica cv. 'Holsteiner Cox') overexpressing the Leaf Colour (Lc) gene from maize (Zea mays) exhibit strongly increased production of anthocyanins and flavan-3-ols (catechins, proanthocyanidins). Greenhouse plants investigated in this study exhibit altered phenotypes with regard to growth habit and resistance traits. Lc-transgenic plants show reduced size, transversal gravitropism of lateral shoots, reduced trichome development, and frequently reduced shoot diameter and abnormal leaf development with fused leaves. Such phenotypes seem to be in accordance with a direct or an indirect effect on polar-auxin-transport in the transgenic plants. Furthermore, leaves often develop necrotic lesions resembling hypersensitive response lesions. In tests, higher resistance against fire blight (caused by the bacterium Erwinia amylovora) and against scab (caused by the fungus Venturia inaequalis) is observed. These phenotypes are discussed with respect to the underlying altered physiology of the Lc-transgenic plants. The results are expected to be considered in apple breeding strategies.
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Affiliation(s)
- Henryk Flachowsky
- Institute for Breeding Research on Horticultural and Fruit Crops, Julius Kühn-Institut, Federal Research Centre for Cultivated Plants, Pillnitzer Platz 3a, 01326 Dresden, Germany
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20
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Pérez-Torres CA, López-Bucio J, Cruz-Ramírez A, Ibarra-Laclette E, Dharmasiri S, Estelle M, Herrera-Estrella L. Phosphate availability alters lateral root development in Arabidopsis by modulating auxin sensitivity via a mechanism involving the TIR1 auxin receptor. THE PLANT CELL 2008; 20:3258-72. [PMID: 19106375 PMCID: PMC2630440 DOI: 10.1105/tpc.108.058719] [Citation(s) in RCA: 338] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2008] [Revised: 11/05/2008] [Accepted: 12/02/2008] [Indexed: 05/12/2023]
Abstract
The survival of plants, as sessile organisms, depends on a series of postembryonic developmental events that determine the final architecture of plants and allow them to contend with a continuously changing environment. Modulation of cell differentiation and organ formation by environmental signals has not been studied in detail. Here, we report that alterations in the pattern of lateral root (LR) formation and emergence in response to phosphate (Pi) availability is mediated by changes in auxin sensitivity in Arabidopsis thaliana roots. These changes alter the expression of auxin-responsive genes and stimulate pericycle cells to proliferate. Modulation of auxin sensitivity by Pi was found to depend on the auxin receptor TRANSPORT INHIBITOR RESPONSE1 (TIR1) and the transcription factor AUXIN RESPONSE FACTOR19 (ARF19). We determined that Pi deprivation increases the expression of TIR1 in Arabidopsis seedlings and causes AUXIN/INDOLE-3-ACETIC ACID (AUX/IAA) auxin response repressors to be degraded. Based on our results, we propose a model in which auxin sensitivity is enhanced in Pi-deprived plants by an increased expression of TIR1, which accelerates the degradation of AUX/IAA proteins, thereby unshackling ARF transcription factors that activate/repress genes involved in LR formation and emergence.
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Affiliation(s)
- Claudia-Anahí Pérez-Torres
- Departamento de Ingeniería Genética de Plantas, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, 36821 Irapuato, Guanajuato, Mexico
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21
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Rahman A, Bannigan A, Sulaman W, Pechter P, Blancaflor EB, Baskin TI. Auxin, actin and growth of the Arabidopsis thaliana primary root. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2007; 50:514-28. [PMID: 17419848 DOI: 10.1111/j.1365-313x.2007.03068.x] [Citation(s) in RCA: 176] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
To understand how auxin regulates root growth, we quantified cell division and elemental elongation, and examined actin organization in the primary root of Arabidopsis thaliana. In treatments for 48 h that inhibited root elongation rate by 50%, we find that auxins and auxin-transport inhibitors can be divided into two classes based on their effects on cell division, elongation and actin organization. Indole acetic acid (IAA), 1-naphthalene acetic acid (NAA) and tri-iodobenzoic acid (TIBA) inhibit root growth primarily through reducing the length of the growth zone rather than the maximal rate of elemental elongation and they do not reduce cell production rate. These three compounds have little effect on the extent of filamentous actin, as imaged in living cells or by chemical fixation and immuno-cytochemistry, but tend to increase actin bundling. In contrast, 2,4-dichlorophenoxy-acetic acid (2,4-D) and naphthylphthalamic acid (NPA) inhibit root growth primarily by reducing cell production rate. These compounds remove actin and slow down cytoplasmic streaming, but do not lead to mislocalization of the auxin-efflux proteins, PIN1 or PIN2. The effects of 2,4-D and NPA were mimicked by the actin inhibitor, latrunculin B. The effects of these compounds on actin were also elicited by a 2 h treatment at higher concentration but were not seen in two mutants, eir1-1 and aux1-7, with deficient auxin transport. Our results show that IAA regulates the size of the root elongation zone whereas 2,4-D affects cell production and actin-dependent processes; and, further, that elemental elongation and localization of PINs are appreciably independent of actin.
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Affiliation(s)
- Abidur Rahman
- Biology Department, University of Massachusetts, Amherst, MA 01003, USA
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Wasson AP, Pellerone FI, Mathesius U. Silencing the flavonoid pathway in Medicago truncatula inhibits root nodule formation and prevents auxin transport regulation by rhizobia. THE PLANT CELL 2006; 18:1617-29. [PMID: 16751348 PMCID: PMC1488924 DOI: 10.1105/tpc.105.038232] [Citation(s) in RCA: 215] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2005] [Revised: 04/18/2006] [Accepted: 05/05/2006] [Indexed: 05/10/2023]
Abstract
Legumes form symbioses with rhizobia, which initiate the development of a new plant organ, the nodule. Flavonoids have long been hypothesized to regulate nodule development through their action as auxin transport inhibitors, but genetic proof has been missing. To test this hypothesis, we used RNA interference to silence chalcone synthase (CHS), the enzyme that catalyzes the first committed step of the flavonoid pathway, in Medicago truncatula. Agrobacterium rhizogenes transformation was used to create hairy roots that showed strongly reduced CHS transcript levels and reduced levels of flavonoids in silenced roots. Flavonoid-deficient roots were unable to initiate nodules, even though normal root hair curling was observed. Nodule formation and flavonoid accumulation could be rescued by supplementation of plants with the precursor flavonoids naringenin and liquiritigenin. The flavonoid-deficient roots showed increased auxin transport compared with control roots. Inoculation with rhizobia reduced auxin transport in control roots after 24 h, similar to the action of the auxin transport inhibitor N-(1-naphthyl)phthalamic acid (NPA). Rhizobia were unable to reduce auxin transport in flavonoid-deficient roots, even though NPA inhibited auxin transport. Our results present genetic evidence that root flavonoids are necessary for nodule initiation in M. truncatula and suggest that they act as auxin transport regulators.
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Affiliation(s)
- Anton P Wasson
- School of Biochemistry and Molecular Biology, Australian Research Council Centre of Excellence for Integrative Legume Research, Australian National University, Canberra ACT 0200, Australia
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Raghavan C, Ong EK, Dalling MJ, Stevenson TW. Regulation of genes associated with auxin, ethylene and ABA pathways by 2,4-dichlorophenoxyacetic acid in Arabidopsis. Funct Integr Genomics 2005; 6:60-70. [PMID: 16317577 DOI: 10.1007/s10142-005-0012-1] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2005] [Revised: 09/15/2005] [Accepted: 09/25/2005] [Indexed: 11/29/2022]
Abstract
The chemical 2,4-dichlorophenoxyacetic acid (2,4-D) regulates plant growth and development and mimics auxins in exhibiting a biphasic mode of action. Although gene regulation in response to the natural auxin indole acetic acid (IAA) has been examined, the molecular mode of action of 2,4-D is poorly understood. Data from biochemical studies, (Grossmann (2000) Mode of action of auxin herbicides: a new ending to a long, drawn out story. Trends Plant Sci 5:506-508) proposed that at high concentrations, auxins and auxinic herbicides induced the plant hormones ethylene and abscisic acid (ABA), leading to inhibited plant growth and senescence. Further, in a recent gene expression study (Raghavan et al. (2005) Effect of herbicidal application of 2,4-dichlorophenoxyacetic acid in Arabidopsis. Funct Integr Genomics 5:4-17), we have confirmed that at high concentrations, 2,4-D induced the expression of the gene NCED1, which encodes 9-cis-epoxycarotenoid dioxygenase, a key regulatory enzyme of ABA biosynthesis. To understand the concentration-dependent mode of action of 2,4-D, we further examined the regulation of whole genome of Arabidopsis in response to a range of 2,4-D concentrations from 0.001 to 1.0 mM, using the ATH1-121501 Arabidopsis whole genome microarray developed by Affymetrix. Results of this study indicated that 2,4-D induced the expression of auxin-response genes (IAA1, IAA13, IAA19) at both auxinic and herbicidal levels of application, whereas the TIR1 and ASK1 genes, which are associated with ubiquitin-mediated auxin signalling, were down-regulated in response to low concentrations of 2,4-D application. It was also observed that in response to low concentrations of 2,4-D, ethylene biosynthesis was induced, as suggested by the up-regulation of genes encoding 1-aminocyclopropane-1-carboxylic acid (ACC) synthase and ACC oxidase. Although genes involved in ethylene biosynthesis were not regulated in response to 0.1 and 1.0 mM 2,4-D, ethylene signalling was induced as indicated by the down-regulation of CTR1 and ERS, both of which play a key role in the ethylene signalling pathway. In response to 1.0 mM 2,4-D, both ABA biosynthesis and signalling were induced, in contrast to the response to lower concentrations of 2,4-D where ABA biosynthesis was suppressed. We present a comprehensive model indicating a molecular mode of action for 2,4-D in Arabidopsis and the effects of this growth regulator on the auxin, ethylene and abscisic acid pathways.
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Affiliation(s)
- Chitra Raghavan
- School of Applied Sciences, RMIT University, Bundoora, Victoria, 3083, Australia
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Dhonukshe P, Kleine-Vehn J, Friml J. Cell polarity, auxin transport, and cytoskeleton-mediated division planes: who comes first? PROTOPLASMA 2005; 226:67-73. [PMID: 16231102 DOI: 10.1007/s00709-005-0104-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2005] [Accepted: 03/30/2005] [Indexed: 05/04/2023]
Abstract
In plants, cell polarity is an issue more recurring than in other systems, because plants, due to their adaptive and flexible development, often change cell polarity postembryonically according to intrinsic cues and demands of the environment. Recent findings on the directional movement of the plant signalling molecule auxin provide a unique connection between individual cell polarity and the establishment of polarity at the tissue, organ, and whole-plant levels. Decisions about the subcellular polar targeting of PIN auxin transport components determine the direction of auxin flow between cells and consequently mediate multiple developmental events. In addition, mutations or chemical interference with PIN-based auxin transport result in abnormal cell divisions. Thus, the complicated links between cell polarity establishment, auxin transport, cytoskeleton, and oriented cell divisions now begin to emerge. Here we review the available literature on the issues of cell polarity in both plants and animals to extend our understanding on the generation, maintenance, and transmission of cell polarity in plants.
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Affiliation(s)
- Pankaj Dhonukshe
- Zentrum für Molekularbiologie der Pflanzen, Universität Tübingen, Tübingen, Federal Republic of Germany.
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Mattsson J, Ckurshumova W, Berleth T. Auxin signaling in Arabidopsis leaf vascular development. PLANT PHYSIOLOGY 2003; 131:1327-39. [PMID: 12644682 PMCID: PMC166892 DOI: 10.1104/pp.013623] [Citation(s) in RCA: 209] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2002] [Revised: 09/09/2002] [Accepted: 11/18/2002] [Indexed: 05/18/2023]
Abstract
A number of observations have implicated auxin in the formation of vascular tissues in plant organs. These include vascular strand formation in response to local auxin application, the effects of impaired auxin transport on vascular patterns and suggestive phenotypes of Arabidopsis auxin response mutants. In this study, we have used molecular markers to visualize auxin response patterns in developing Arabidopsis leaves as well as Arabidopsis mutants and transgenic plants to trace pathways of auxin signal transduction controlling the expression of early procambial genes. We show that in young Arabidopsis leaf primordia, molecular auxin response patterns presage sites of procambial differentiation. This is the case not only in normal development but also upon experimental manipulation of auxin transport suggesting that local auxin signals are instrumental in patterning Arabidopsis leaf vasculature. We further found that the activity of the Arabidopsis gene MONOPTEROS, which is required for proper vascular differentiation, is also essential in a spectrum of auxin responses, which include the regulation of rapidly auxin-inducible AUX/IAA genes, and discovered the tissue-specific vascular expression profile of the class I homeodomain-leucine zipper gene, AtHB20. Interestingly, MONOPTEROS activity is a limiting factor in the expression of AtHB8 and AtHB20, two genes encoding transcriptional regulators expressed early in procambial development. Our observations connect general auxin signaling with early controls of vascular differentiation and suggest molecular mechanisms for auxin signaling in patterned cell differentiation.
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Affiliation(s)
- Jim Mattsson
- Department of Botany, University of Toronto, 25 Willcocks Street, Toronto, Canada M5S 3B2
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KAWANO NAKAKO, KAWANO TOMONORI, LAPEYRIE FREDERIC. Inhibition of the indole-3-acetic acid-induced epinastic curvature in tobacco leaf strips by 2,4-dichlorophenoxyacetic acid. ANNALS OF BOTANY 2003; 91:465-71. [PMID: 12588726 PMCID: PMC4241065 DOI: 10.1093/aob/mcg043] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
It has been reported that auxin induces an epinastic growth response in plant leaf tissues. Leaf strips of tobacco (Nicotiana tabacum L. 'Bright Yellow 2') were used to study the effects of indole-3-acetic acid (IAA), the principal form of auxin in higher plants, and a synthetic auxin, 2,4-dichlorophenoxyacetic acid (2,4-D), on epinastic leaf curvature. Incubation of leaf strips with 10 micro M IAA resulted in a marked epinastic curvature response. Unexpectedly, 2,4-D showed only a weak IAA-like activity in inducing epinasty. Interestingly, the presence of 2,4-D resulted in inhibition of the IAA-dependent epinastic curvature. In vivo Lineweaver-Burk kinetic analysis clearly indicated that the interaction between IAA and 2,4-D reported here is not a result of competitive inhibition. Using kinetic analysis, it was not possible to determine whether the mode of interaction between IAA and 2,4-D was non-competitive or uncompetitive. 2,4-D inhibits the IAA-dependent epinasty via complex and as yet unidentified mechanisms.
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Affiliation(s)
- NAKAKO KAWANO
- Unité Mixte de Recherche INRA‐UHP Interactions Arbres/Micro‐organismes, Institut National de la Recherche Agronomique, F‐54280 Champenoux, France
| | - TOMONORI KAWANO
- Unité Mixte de Recherche INRA‐UHP Interactions Arbres/Micro‐organismes, Institut National de la Recherche Agronomique, F‐54280 Champenoux, France
- Department of Biological Science, Graduate School of Science, Hiroshima University, Higashi‐Hiroshima, Japan
| | - FREDERIC LAPEYRIE
- Unité Mixte de Recherche INRA‐UHP Interactions Arbres/Micro‐organismes, Institut National de la Recherche Agronomique, F‐54280 Champenoux, France
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Becker D, Hedrich R. Channelling auxin action: modulation of ion transport by indole-3-acetic acid. PLANT MOLECULAR BIOLOGY 2002; 49:349-356. [PMID: 12036259 DOI: 10.1023/a:1015211231864] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The growth hormone auxin is a key regulator of plant cell division and elongation. Since plants lack muscles, processes involved in growth and movements rely on turgor formation, and thus on the transport of solutes and water. Modern electrophysiological techniques and molecular genetics have shed new light on the regulation of plant ion transporters in response to auxin. Guard cells, hypocotyls and coleoptiles have advanced to major model systems in studying auxin action. This review will therefore focus on the molecular mechanism by which auxin modulates ion transport and cell expansion in these model cell types.
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Affiliation(s)
- Dirk Becker
- Biocenter, Julius-von-Sachs-Institut for Biosciences, Department of Plant Molecular Physiology and Biophysics, Würzburg, Germany.
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Kawano T, Kawano N, Hosoya H, Lapeyrie F. Fungal auxin antagonist hypaphorine competitively inhibits indole-3-acetic acid-dependent superoxide generation by horseradish peroxidase. Biochem Biophys Res Commun 2001; 288:546-51. [PMID: 11676477 DOI: 10.1006/bbrc.2001.5800] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Plant peroxidases (EC 1.11.1.7) including horseradish peroxidase (HRP-C), but not the nonplant peroxidases, are known to be highly specific indole-3-acetic acid (IAA) oxygenases which oxidize IAA in the absence of H2O2, and superoxide anion radicals (O2*-) are produced as by-products. Hypaphorine, a putative auxin antagonist isolated from ectomycorrhizal fungi, inhibited the IAA-dependent generation of O2*- by HRP-C, which occurs in the absence of H2O2. Hypaphorine has no effect on the nonspecific heme-catalyzed O2*- generation induced by high concentration of ethanol. It is probable that the inhibitory effect of hypaphorine on O2*- generation is highly specific to the IAA-dependent reaction. The mode of inhibition of the IAA-dependent O2*--generating reaction by hypaphorine was analyzed with a double-reciprocal plot and determined to be competitive inhibition, indicating that hypaphorine competes with IAA by binding to the putative IAA binding site on HRP-C. This implies the importance of structural similarity between hypaphorine and IAA. This work presented the first evidence for antagonism between IAA and a structurally related fungal alkaloid on binding to a purified protein which shares some structural similarity with auxin-binding proteins.
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Affiliation(s)
- T Kawano
- Unité Mixte de Recherche INRA-UHP Interactions Arbres/Micro-organismes, Institut National de la Recherche Agronomique, Champenoux, F-54280, France
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29
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Abstract
Auxins are a class of phytohormones implicated in virtually every aspect of plant growth and development. Many early plant responses to auxin are apparently mediated by members of a family of Aux/IAA proteins that dimerize with and inhibit members of the auxin response factor (ARF) family of transcription factors. Aux/IAA proteins are unstable, and their degradation is triggered by a ubiquitin-protein ligase that is regulated by modification with a ubiquitin-related protein. Recent genetic and biochemical evidence indicates that auxin accelerates the degradation of the already short-lived Aux/IAA proteins to derepress transcription by ARF proteins. Several pieces of the auxin-signaling puzzle remain to be assembled, including the proteins that initially bind auxin, the proteins that convey this signal to the protein degradation machinery, and the targets of the transcriptional derepression.
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Affiliation(s)
- L E Rogg
- Department of Biochemistry and Cell Biology, Rice University, Houston, TX 77005, USA
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30
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Brown DE, Rashotte AM, Murphy AS, Normanly J, Tague BW, Peer WA, Taiz L, Muday GK. Flavonoids act as negative regulators of auxin transport in vivo in arabidopsis. PLANT PHYSIOLOGY 2001; 126:524-35. [PMID: 11402184 PMCID: PMC111146 DOI: 10.1104/pp.126.2.524] [Citation(s) in RCA: 428] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2000] [Revised: 12/14/2000] [Accepted: 01/21/2001] [Indexed: 05/17/2023]
Abstract
Polar transport of the plant hormone auxin controls many aspects of plant growth and development. A number of synthetic compounds have been shown to block the process of auxin transport by inhibition of the auxin efflux carrier complex. These synthetic auxin transport inhibitors may act by mimicking endogenous molecules. Flavonoids, a class of secondary plant metabolic compounds, have been suggested to be auxin transport inhibitors based on their in vitro activity. The hypothesis that flavonoids regulate auxin transport in vivo was tested in Arabidopsis by comparing wild-type (WT) and transparent testa (tt4) plants with a mutation in the gene encoding the first enzyme in flavonoid biosynthesis, chalcone synthase. In a comparison between tt4 and WT plants, phenotypic differences were observed, including three times as many secondary inflorescence stems, reduced plant height, decreased stem diameter, and increased secondary root development. Growth of WT Arabidopsis plants on naringenin, a biosynthetic precursor to those flavonoids with auxin transport inhibitor activity in vitro, leads to a reduction in root growth and gravitropism, similar to the effects of synthetic auxin transport inhibitors. Analyses of auxin transport in the inflorescence and hypocotyl of independent tt4 alleles indicate that auxin transport is elevated in plants with a tt4 mutation. In hypocotyls of tt4, this elevated transport is reversed when flavonoids are synthesized by growth of plants on the flavonoid precursor, naringenin. These results are consistent with a role for flavonoids as endogenous regulators of auxin transport.
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Affiliation(s)
- D E Brown
- Department of Biology, Wake Forest University, Winston-Salem, North Carolina 27109, USA
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31
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Casimiro I, Marchant A, Bhalerao RP, Beeckman T, Dhooge S, Swarup R, Graham N, Inzé D, Sandberg G, Casero PJ, Bennett M. Auxin transport promotes Arabidopsis lateral root initiation. THE PLANT CELL 2001; 13:843-52. [PMID: 11283340 PMCID: PMC135543 DOI: 10.1105/tpc.13.4.843] [Citation(s) in RCA: 668] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Lateral root development in Arabidopsis provides a model for the study of hormonal signals that regulate postembryonic organogenesis in higher plants. Lateral roots originate from pairs of pericycle cells, in several cell files positioned opposite the xylem pole, that initiate a series of asymmetric, transverse divisions. The auxin transport inhibitor N-1-naphthylphthalamic acid (NPA) arrests lateral root development by blocking the first transverse division(s). We investigated the basis of NPA action by using a cell-specific reporter to demonstrate that xylem pole pericycle cells retain their identity in the presence of the auxin transport inhibitor. However, NPA causes indoleacetic acid (IAA) to accumulate in the root apex while reducing levels in basal tissues critical for lateral root initiation. This pattern of IAA redistribution is consistent with NPA blocking basipetal IAA movement from the root tip. Characterization of lateral root development in the shoot meristemless1 mutant demonstrates that root basipetal and leaf acropetal auxin transport activities are required during the initiation and emergence phases, respectively, of lateral root development.
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Affiliation(s)
- I Casimiro
- Departmento de Ciencias Morfologicas y Biologia Celular y Animal, University of Extremadura, Badajoz, Spain
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32
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Parry G, Delbarre A, Marchant A, Swarup R, Napier R, Perrot-Rechenmann C, Bennett MJ. Novel auxin transport inhibitors phenocopy the auxin influx carrier mutation aux1. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2001; 25:399-406. [PMID: 11260496 DOI: 10.1046/j.1365-313x.2001.00970.x] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The hormone auxin is transported in plants through the combined actions of diffusion and specific auxin influx and efflux carriers. In contrast to auxin efflux, for which there are well documented inhibitors, understanding the developmental roles of carrier-mediated auxin influx has been hampered by the absence of specific competitive inhibitors. However, several molecules that inhibit auxin influx in cultured cells have been described recently. The physiological effects of two of these novel influx carrier inhibitors, 1-naphthoxyacetic acid (1-NOA) and 3-chloro-4-hydroxyphenylacetic acid (CHPAA), have been investigated in intact seedlings and tissue segments using classical and new auxin transport bioassays. Both molecules do disrupt root gravitropism, which is a developmental process requiring rapid auxin redistribution. Furthermore, the auxin-insensitive and agravitropic root-growth characteristics of aux1 plants were phenocopied by 1-NOA and CHPAA. Similarly, the agravitropic phenotype of inhibitor-treated seedlings was rescued by the auxin 1-naphthaleneacetic acid, but not by 2,4-dichlorophenoxyacetic acid, again resembling the relative abilities of these two auxins to rescue the phenotype of aux1. Further investigations have shown that none of these compounds block polar auxin transport, and that CHPAA exhibits some auxin-like activity at high concentrations. Whilst results indicate that 1-NOA and CHPAA represent useful tools for physiological studies addressing the role of auxin influx in planta, 1-NOA is likely to prove the more useful of the two compounds.
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Affiliation(s)
- G Parry
- Division of Plant Sciences, School of Biosciences, University of Nottingham, Nottingham NG7 2RD, UK
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33
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Zolman BK, Yoder A, Bartel B. Genetic analysis of indole-3-butyric acid responses in Arabidopsis thaliana reveals four mutant classes. Genetics 2000; 156:1323-37. [PMID: 11063705 PMCID: PMC1461311 DOI: 10.1093/genetics/156.3.1323] [Citation(s) in RCA: 206] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Indole-3-butyric acid (IBA) is widely used in agriculture because it induces rooting. To better understand the in vivo role of this endogenous auxin, we have identified 14 Arabidopsis mutants that are resistant to the inhibitory effects of IBA on root elongation, but that remain sensitive to the more abundant auxin indole-3-acetic acid (IAA). These mutants have defects in various IBA-mediated responses, which allowed us to group them into four phenotypic classes. Developmental defects in the absence of exogenous sucrose suggest that some of these mutants are impaired in peroxisomal fatty acid chain shortening, implying that the conversion of IBA to IAA is also disrupted. Other mutants appear to have normal peroxisomal function; some of these may be defective in IBA transport, signaling, or response. Recombination mapping indicates that these mutants represent at least nine novel loci in Arabidopsis. The gene defective in one of the mutants was identified using a positional approach and encodes PEX5, which acts in the import of most peroxisomal matrix proteins. These results indicate that in Arabidopsis thaliana, IBA acts, at least in part, via its conversion to IAA.
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Affiliation(s)
- B K Zolman
- Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005, USA
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34
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Scarpella E, Rueb S, Boot KJ, Hoge JH, Meijer AH. A role for the rice homeobox gene Oshox1 in provascular cell fate commitment. Development 2000; 127:3655-69. [PMID: 10934011 DOI: 10.1242/dev.127.17.3655] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The vascular tissues of plants form a network of interconnected cell files throughout the plant body. The transition from a genetically totipotent meristematic precursor to different stages of a committed procambial cell, and its subsequent differentiation into a mature vascular element, involves developmental events whose molecular nature is still mostly unknown. The rice protein Oshox1 is a member of the homeodomain leucine zipper family of transcription factors. Here we show that the strikingly precise onset of Oshox1 gene expression marks critical, early stages of provascular ontogenesis in which the developmental fate of procambial cells is specified but not yet stably determined. This suggests that the Oshox1 gene may be involved in the establishment of the conditions required to restrict the developmental potential of procambial cells. In support of this hypothesis, ectopic expression of Oshox1 in provascular cells that normally do not yet express this gene results in anticipation of procambial cell fate commitment, eventually culminating in premature vascular differentiation. Oshox1 represents the first example of a transcription factor whose function can be linked to specification events mediating provascular cell fate commitment.
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Affiliation(s)
- E Scarpella
- Institute of Molecular Plant Sciences, Leiden University, Clusius Laboratory, PO Box 9505, The Netherlands
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35
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Abstract
The root forms at the basal end of an axis that is set up early in embryogenesis, and recent genetic analysis has indicated that auxin transport is required for the formation of the root pole. Drug studies show that auxin transport is also required for the maintenance of the tissue organisation in the seedling root. These studies support existing models for tissue patterning that involve canalised auxin flow. Molecular insights into the mechanism of cell-type specification and patterning has come from the epidermis where positionally controlled cell specification is regulated by a cascade of transcription factors.
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Affiliation(s)
- S Costa
- Department of Cell Biology, John Innes Centre, Norwich, UK.
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36
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Palme K, Gälweiler L. PIN-pointing the molecular basis of auxin transport. CURRENT OPINION IN PLANT BIOLOGY 1999; 2:375-381. [PMID: 10508762 DOI: 10.1016/s1369-5266(99)00008-4] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Significant advances in the genetic dissection of the auxin transport pathway have recently been made. Particularly relevant is the molecular analysis of mutants impaired in auxin transport and the subsequent cloning of genes encoding candidate proteins for the elusive auxin efflux carrier. These studies are thought to pave the way to the detailed understanding of the molecular basis of several important facets of auxin action.
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Affiliation(s)
- K Palme
- Max-Delbrück-Laboratorium in der Max-Planck-Gesellschaft, Carl-von-Linné-Weg 10, D-50829, Köln, Germany.
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37
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Mattsson J, Sung ZR, Berleth T. Responses of plant vascular systems to auxin transport inhibition. Development 1999; 126:2979-91. [PMID: 10357941 DOI: 10.1242/dev.126.13.2979] [Citation(s) in RCA: 271] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
To assess the role of auxin flows in plant vascular patterning, the development of vascular systems under conditions of inhibited auxin transport was analyzed. In Arabidopsis, nearly identical responses evoked by three auxin transport inhibitor substances revealed an enormous plasticity of the vascular pattern and suggest an involvement of auxin flows in determining the sites of vascular differentiation and in promoting vascular tissue continuity. Organs formed under conditions of reduced auxin transport contained increased numbers of vascular strands and cells within those strands were improperly aligned. In leaves, vascular tissues became progressively confined towards the leaf margin as the concentration of auxin transport inhibitor was increased, suggesting that the leaf vascular system depends on inductive signals from the margin of the leaf. Staged application of auxin transport inhibitor demonstrated that primary, secondary and tertiary veins became unresponsive to further modulations of auxin transport at successive stages of early leaf development. Correlation of these stages to anatomical features in early leaf primordia indicated that the pattern of primary and secondary strands becomes fixed at the onset of lamina expansion. Similar alterations in the leaf vascular responses of alyssum, snapdragon and tobacco plants suggest common functions of auxin flows in vascular patterning in dicots, while two types of vascular pattern alterations in Arabidopsis auxin transport mutants suggest that at least two distinct primary defects can result in impaired auxin flow. We discuss these observations with regard to the relative contributions of auxin transport, auxin sensitivity and the cellular organisation of the developing organ on the vascular pattern.
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Affiliation(s)
- J Mattsson
- Department of Plant and Microbial Biology, University of California, Berkeley CA 94720, USA.
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38
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Marchant A, Kargul J, May ST, Muller P, Delbarre A, Perrot-Rechenmann C, Bennett MJ. AUX1 regulates root gravitropism in Arabidopsis by facilitating auxin uptake within root apical tissues. EMBO J 1999; 18:2066-73. [PMID: 10205161 PMCID: PMC1171291 DOI: 10.1093/emboj/18.8.2066] [Citation(s) in RCA: 409] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Plants employ a specialized transport system composed of separate influx and efflux carriers to mobilize the plant hormone auxin between its site(s) of synthesis and action. Mutations within the permease-like AUX1 protein significantly reduce the rate of carrier-mediated auxin uptake within Arabidopsis roots, conferring an agravitropic phenotype. We are able to bypass the defect within auxin uptake and restore the gravitropic root phenotype of aux1 by growing mutant seedlings in the presence of the membrane-permeable synthetic auxin, 1-naphthaleneacetic acid. We illustrate that AUX1 expression overlaps that previously described for the auxin efflux carrier, AtPIN2, using transgenic lines expressing an AUX1 promoter::uidA (GUS) gene. Finally, we demonstrate that AUX1 regulates gravitropic curvature by acting in unison with the auxin efflux carrier to co-ordinate the localized redistribution of auxin within the Arabidopsis root apex. Our results provide the first example of a developmental role for the auxin influx carrier within higher plants and supply new insight into the molecular basis of gravitropic signalling.
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Affiliation(s)
- A Marchant
- Division of Plant Sciences, School of Biological Sciences, University of Nottingham, NG7 2RD, UK
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