101
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Boer DR, Freire-Rios A, van den Berg WAM, Saaki T, Manfield IW, Kepinski S, López-Vidrieo I, Franco-Zorrilla JM, de Vries SC, Solano R, Weijers D, Coll M. Structural basis for DNA binding specificity by the auxin-dependent ARF transcription factors. Cell 2014; 156:577-89. [PMID: 24485461 DOI: 10.1016/j.cell.2013.12.027] [Citation(s) in RCA: 246] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 11/22/2013] [Accepted: 12/11/2013] [Indexed: 10/25/2022]
Abstract
Auxin regulates numerous plant developmental processes by controlling gene expression via a family of functionally distinct DNA-binding auxin response factors (ARFs), yet the mechanistic basis for generating specificity in auxin response is unknown. Here, we address this question by solving high-resolution crystal structures of the pivotal Arabidopsis developmental regulator ARF5/MONOPTEROS (MP), its divergent paralog ARF1, and a complex of ARF1 and a generic auxin response DNA element (AuxRE). We show that ARF DNA-binding domains also homodimerize to generate cooperative DNA binding, which is critical for in vivo ARF5/MP function. Strikingly, DNA-contacting residues are conserved between ARFs, and we discover that monomers have the same intrinsic specificity. ARF1 and ARF5 homodimers, however, differ in spacing tolerated between binding sites. Our data identify the DNA-binding domain as an ARF dimerization domain, suggest that ARF dimers bind complex sites as molecular calipers with ARF-specific spacing preference, and provide an atomic-scale mechanistic model for specificity in auxin response.
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Affiliation(s)
- D Roeland Boer
- Institute for Research in Biomedicine (IRB Barcelona), Baldiri Reixac 10-12, 08028 Barcelona, Spain; Institut de Biologia Molecular de Barcelona (IBMB-CSIC), Baldiri Reixac 10-12, 08028 Barcelona, Spain
| | - Alejandra Freire-Rios
- Laboratory of Biochemistry, Wageningen University, Dreijenlaan 3, 6703 HA Wageningen, the Netherlands
| | - Willy A M van den Berg
- Laboratory of Biochemistry, Wageningen University, Dreijenlaan 3, 6703 HA Wageningen, the Netherlands
| | - Terrens Saaki
- Laboratory of Biochemistry, Wageningen University, Dreijenlaan 3, 6703 HA Wageningen, the Netherlands
| | - Iain W Manfield
- Astbury Centre for Structural Molecular Biology (IWM) and Centre for Plant Sciences (SK), Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Stefan Kepinski
- Astbury Centre for Structural Molecular Biology (IWM) and Centre for Plant Sciences (SK), Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Irene López-Vidrieo
- Genomics Unit and Department of Plant Molecular Genetics, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, Campus Universidad Autónoma, 28049 Madrid, Spain
| | - Jose Manuel Franco-Zorrilla
- Genomics Unit and Department of Plant Molecular Genetics, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, Campus Universidad Autónoma, 28049 Madrid, Spain
| | - Sacco C de Vries
- Laboratory of Biochemistry, Wageningen University, Dreijenlaan 3, 6703 HA Wageningen, the Netherlands
| | - Roberto Solano
- Genomics Unit and Department of Plant Molecular Genetics, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, Campus Universidad Autónoma, 28049 Madrid, Spain
| | - Dolf Weijers
- Laboratory of Biochemistry, Wageningen University, Dreijenlaan 3, 6703 HA Wageningen, the Netherlands.
| | - Miquel Coll
- Institute for Research in Biomedicine (IRB Barcelona), Baldiri Reixac 10-12, 08028 Barcelona, Spain; Institut de Biologia Molecular de Barcelona (IBMB-CSIC), Baldiri Reixac 10-12, 08028 Barcelona, Spain.
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102
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Kania U, Fendrych M, Friml J. Polar delivery in plants; commonalities and differences to animal epithelial cells. Open Biol 2014; 4:140017. [PMID: 24740985 PMCID: PMC4043115 DOI: 10.1098/rsob.140017] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Although plant and animal cells use a similar core mechanism to deliver proteins
to the plasma membrane, their different lifestyle, body organization and
specific cell structures resulted in the acquisition of regulatory mechanisms
that vary in the two kingdoms. In particular, cell polarity regulators do not
seem to be conserved, because genes encoding key components are absent in plant
genomes. In plants, the broad knowledge on polarity derives from the study of
auxin transporters, the PIN-FORMED proteins, in the model plant
Arabidopsis thaliana. In animals, much information is
provided from the study of polarity in epithelial cells that exhibit basolateral
and luminal apical polarities, separated by tight junctions. In this review, we
summarize the similarities and differences of the polarization mechanisms
between plants and animals and survey the main genetic approaches that have been
used to characterize new genes involved in polarity establishment in plants,
including the frequently used forward and reverse genetics screens as well as a
novel chemical genetics approach that is expected to overcome the limitation of
classical genetics methods.
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Affiliation(s)
- Urszula Kania
- Institute of Science and Technology Austria (IST Austria), 3400 Klosterneuburg, Austria
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103
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Ganguly A, Park M, Kesawat MS, Cho HT. Functional Analysis of the Hydrophilic Loop in Intracellular Trafficking of Arabidopsis PIN-FORMED Proteins. THE PLANT CELL 2014; 26:1570-1585. [PMID: 24692422 PMCID: PMC4036572 DOI: 10.1105/tpc.113.118422] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 03/03/2014] [Accepted: 03/18/2014] [Indexed: 05/18/2023]
Abstract
Different PIN-FORMED proteins (PINs) contribute to intercellular and intracellular auxin transport, depending on their distinctive subcellular localizations. Arabidopsis thaliana PINs with a long hydrophilic loop (HL) (PIN1 to PIN4 and PIN7; long PINs) localize predominantly to the plasma membrane (PM), whereas short PINs (PIN5 and PIN8) localize predominantly to internal compartments. However, the subcellular localization of the short PINs has been observed mostly for PINs ectopically expressed in different cell types, and the role of the HL in PIN trafficking remains unclear. Here, we tested whether a long PIN-HL can provide its original molecular cues to a short PIN by transplanting the HL. The transplanted long PIN2-HL was sufficient for phosphorylation and PM trafficking of the chimeric PIN5:PIN2-HL but failed to provide the characteristic polarity of PIN2. Unlike previous observations, PIN5 showed clear PM localization in diverse cell types where PIN5 is natively or ectopically expressed and even polar PM localization in one cell type. Furthermore, in the root epidermis, the subcellular localization of PIN5 switched from PM to internal compartments according to the developmental stage. Our results suggest that the long PIN-HL is partially modular for the trafficking behavior of PINs and that the intracellular trafficking of PIN is plastic depending on cell type and developmental stage.
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Affiliation(s)
- Anindya Ganguly
- Department of Biological Sciences and Plant Genomics and Breeding Institute, Seoul National University, Seoul 151-742, Korea
| | - Minho Park
- Department of Biological Sciences and Plant Genomics and Breeding Institute, Seoul National University, Seoul 151-742, Korea
| | - Mahipal Singh Kesawat
- Department of Biological Sciences and Plant Genomics and Breeding Institute, Seoul National University, Seoul 151-742, Korea
| | - Hyung-Taeg Cho
- Department of Biological Sciences and Plant Genomics and Breeding Institute, Seoul National University, Seoul 151-742, Korea
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104
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Tian H, Wabnik K, Niu T, Li H, Yu Q, Pollmann S, Vanneste S, Govaerts W, Rolcík J, Geisler M, Friml J, Ding Z. WOX5-IAA17 feedback circuit-mediated cellular auxin response is crucial for the patterning of root stem cell niches in Arabidopsis. MOLECULAR PLANT 2014; 7:277-89. [PMID: 23939433 DOI: 10.1093/mp/sst118] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
In plants, the patterning of stem cell-enriched meristems requires a graded auxin response maximum that emerges from the concerted action of polar auxin transport, auxin biosynthesis, auxin metabolism, and cellular auxin response machinery. However, mechanisms underlying this auxin response maximum-mediated root stem cell maintenance are not fully understood. Here, we present unexpected evidence that WUSCHEL-RELATED HOMEOBOX 5 (WOX5) transcription factor modulates expression of auxin biosynthetic genes in the quiescent center (QC) of the root and thus provides a robust mechanism for the maintenance of auxin response maximum in the root tip. This WOX5 action is balanced through the activity of indole-3-acetic acid 17 (IAA17) auxin response repressor. Our combined genetic, cell biology, and computational modeling studies revealed a previously uncharacterized feedback loop linking WOX5-mediated auxin production to IAA17-dependent repression of auxin responses. This WOX5-IAA17 feedback circuit further assures the maintenance of auxin response maximum in the root tip and thereby contributes to the maintenance of distal stem cell (DSC) populations. Our experimental studies and in silico computer simulations both demonstrate that the WOX5-IAA17 feedback circuit is essential for the maintenance of auxin gradient in the root tip and the auxin-mediated root DSC differentiation.
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Affiliation(s)
- Huiyu Tian
- The Key Laboratory of Plant Cell Engineering and Germplasm Innovation, Ministry of Education, School of Life Sciences, Shandong University, Shanda Nanlu 27, Jinan 250100, China
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105
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Auxin transport and activity regulate stomatal patterning and development. Nat Commun 2014; 5:3090. [DOI: 10.1038/ncomms4090] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2013] [Accepted: 12/11/2013] [Indexed: 11/09/2022] Open
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106
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Abstract
ROPs (Rho of plants) belong to a large family of plant-specific Rho-like small GTPases that function as essential molecular switches to control diverse cellular processes including cytoskeleton organization, cell polarization, cytokinesis, cell differentiation and vesicle trafficking. Although the machineries of vesicle trafficking and cell polarity in plants have been individually well addressed, how ROPs co-ordinate those processes is still largely unclear. Recent progress has been made towards an understanding of the co-ordination of ROP signalling and trafficking of PIN (PINFORMED) transporters for the plant hormone auxin in both root and leaf pavement cells. PIN transporters constantly shuttle between the endosomal compartments and the polar plasma membrane domains, therefore the modulation of PIN-dependent auxin transport between cells is a main developmental output of ROP-regulated vesicle trafficking. The present review focuses on these cellular mechanisms, especially the integration of ROP-based vesicle trafficking and plant cell polarity.
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107
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Geisler M, Wang B, Zhu J. Auxin transport during root gravitropism: transporters and techniques. PLANT BIOLOGY (STUTTGART, GERMANY) 2014; 16 Suppl 1:50-7. [PMID: 23648074 DOI: 10.1111/plb.12030] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Accepted: 02/28/2013] [Indexed: 05/04/2023]
Abstract
Root gravitropism is a complex, plant-specific process allowing roots to grow downward into the soil. Polar auxin transport and redistribution are essential for root gravitropism. Here we summarise our current understanding of underlying molecular mechanisms and involved transporters that establish, maintain and redirect intercellular auxin gradients as the driving force for root gravitropism. We evaluate the genetic, biochemical and cell biological approaches presently used for the analysis of auxin redistribution and the quantification of auxin fluxes. Finally, we also discuss new tools that provide a higher spatial or temporal resolution and our technical needs for future gravitropism studies.
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Affiliation(s)
- M Geisler
- Department of Biology - Plant Biology, University of Fribourg, Fribourg, Switzerland
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108
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Nisar N, Cuttriss AJ, Pogson BJ, Cazzonelli CI. The promoter of the Arabidopsis PIN6 auxin transporter enabled strong expression in the vasculature of roots, leaves, floral stems and reproductive organs. PLANT SIGNALING & BEHAVIOR 2014; 9:e27898. [PMID: 24487186 PMCID: PMC4091377 DOI: 10.4161/psb.27898] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Cellular auxin homeostasis controls many aspects of plant growth, organogenesis and development. The existence of intracellular auxin transport mediated by endoplasmic reticulum (ER)-localized PIN5, PIN6 and PIN8 proteins is a relatively recent discovery shaping a new era in understanding auxin-mediated growth processes. Here we summarize the importance of PIN6 in mediating intracellular auxin transport during root formation, leaf vein patterning and nectary production. While, it was previously shown that PIN6 was strongly expressed in rosette leaf cell types important in vein formation, here we demonstrate by use a PIN6 promoter-reporter fusion, that PIN6 is also preferentially expressed in the vasculature of the primary root, cotyledons, cauline leaves, floral stem, sepals and the main transmitting tract of the reproductive silique. The strong, vein- specific reporter gene expression patterns enabled by the PIN6 promoter emphasizes that transcriptional control is likely to be a major regulator of PIN6 protein levels, during vasculature formation, and supports the need for ER-localized PIN proteins in selecting specialized cells for vascular function in land plants.
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109
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Liscum E, Askinosie SK, Leuchtman DL, Morrow J, Willenburg KT, Coats DR. Phototropism: growing towards an understanding of plant movement. THE PLANT CELL 2014; 26:38-55. [PMID: 24481074 PMCID: PMC3963583 DOI: 10.1105/tpc.113.119727] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2013] [Revised: 12/31/2013] [Accepted: 01/06/2014] [Indexed: 05/19/2023]
Abstract
Phototropism, or the differential cell elongation exhibited by a plant organ in response to directional blue light, provides the plant with a means to optimize photosynthetic light capture in the aerial portion and water and nutrient acquisition in the roots. Tremendous advances have been made in our understanding of the molecular, biochemical, and cellular bases of phototropism in recent years. Six photoreceptors and their associated signaling pathways have been linked to phototropic responses under various conditions. Primary detection of directional light occurs at the plasma membrane, whereas secondary modulatory photoreception occurs in the cytoplasm and nucleus. Intracellular responses to light cues are processed to regulate cell-to-cell movement of auxin to allow establishment of a trans-organ gradient of the hormone. Photosignaling also impinges on the transcriptional regulation response established as a result of changes in local auxin concentrations. Three additional phytohormone signaling pathways have also been shown to influence phototropic responsiveness, and these pathways are influenced by the photoreceptor signaling as well. Here, we will discuss this complex dance of intra- and intercellular responses that are regulated by these many systems to give rise to a rapid and robust adaptation response observed as organ bending.
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Affiliation(s)
- Emmanuel Liscum
- Division of Biological Sciences, University of Missouri, Columbia, Missouri 65211
- Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211
- Address correspondence to
| | - Scott K. Askinosie
- Division of Biological Sciences, University of Missouri, Columbia, Missouri 65211
- Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211
| | - Daniel L. Leuchtman
- Division of Biological Sciences, University of Missouri, Columbia, Missouri 65211
- Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211
| | - Johanna Morrow
- Division of Biological Sciences, University of Missouri, Columbia, Missouri 65211
- Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211
| | - Kyle T. Willenburg
- Division of Biological Sciences, University of Missouri, Columbia, Missouri 65211
- Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211
| | - Diana Roberts Coats
- Division of Biological Sciences, University of Missouri, Columbia, Missouri 65211
- Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211
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110
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Tanaka K, Hayashi KI, Natsume M, Kamiya Y, Sakakibara H, Kawaide H, Kasahara H. UGT74D1 catalyzes the glucosylation of 2-oxindole-3-acetic acid in the auxin metabolic pathway in Arabidopsis. PLANT & CELL PHYSIOLOGY 2014; 55:218-28. [PMID: 24285754 PMCID: PMC3894777 DOI: 10.1093/pcp/pct173] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 11/19/2013] [Indexed: 05/18/2023]
Abstract
IAA is a naturally occurring auxin that plays a crucial role in the regulation of plant growth and development. The endogenous concentration of IAA is spatiotemporally regulated by biosynthesis, transport and its inactivation in plants. Previous studies have shown that the metabolism of IAA to 2-oxindole-3-acetic acid (OxIAA) and OxIAA-glucoside (OxIAA-Glc) may play an important role in IAA homeostasis, but the genes involved in this metabolic pathway are still unknown. In this study, we show that UGT74D1 catalyzes the glucosylation of OxIAA in Arabidopsis. By screening yeasts transformed with Arabidopsis UDP-glycosyltransferase (UGT) genes, we found that OxIAA-Glc accumulates in the culture media of yeasts expressing UGT74D1 in the presence of OxIAA. Further, we showed that UGT74D1 expressed in Escherichia coli converts OxIAA to OxIAA-Glc. The endogenous concentration of OxIAA-Glc decreased by 85% while that of OxIAA increased 2.5-fold in ugt74d1-deficient mutants, indicating the major role of UGT74D1 in OxIAA metabolism. Moreover, the induction of UGT74D1 markedly increased the level of OxIAA-Glc and loss of root gravitropism. These results indicate that UGT74D1 catalyzes a committed step in the OxIAA-dependent IAA metabolic pathway in Arabidopsis.
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Affiliation(s)
- Keita Tanaka
- United Graduate School of Agricultural Science, Tokyo
University of Agriculture & Technology, Tokyo, 183-8509 Japan
- RIKEN Center for Sustainable Resource Science, Yokohama,
Kanagawa, 230-0045 Japan
| | - Ken-ichiro Hayashi
- Department of Biochemistry, Okayama University of Science,
Okayama, 700-0005 Japan
| | - Masahiro Natsume
- United Graduate School of Agricultural Science, Tokyo
University of Agriculture & Technology, Tokyo, 183-8509 Japan
| | - Yuji Kamiya
- RIKEN Center for Sustainable Resource Science, Yokohama,
Kanagawa, 230-0045 Japan
| | - Hitoshi Sakakibara
- RIKEN Center for Sustainable Resource Science, Yokohama,
Kanagawa, 230-0045 Japan
| | - Hiroshi Kawaide
- United Graduate School of Agricultural Science, Tokyo
University of Agriculture & Technology, Tokyo, 183-8509 Japan
| | - Hiroyuki Kasahara
- RIKEN Center for Sustainable Resource Science, Yokohama,
Kanagawa, 230-0045 Japan
- Japan Science and Technology Agency (JST), Precursory
Research for Embryonic Science and Technology (PRESTO), Saitama, 332-0012 Japan
- *Corresponding author: E-mail,
; Fax +81-45-503-9665
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111
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Ueda J, Miyamoto K, Uheda E, Oka M, Yano S, Higashibata A, Ishioka N. Close relationships between polar auxin transport and graviresponse in plants. PLANT BIOLOGY (STUTTGART, GERMANY) 2014; 16 Suppl 1:43-49. [PMID: 24128007 DOI: 10.1111/plb.12101] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Accepted: 07/18/2013] [Indexed: 06/02/2023]
Abstract
Gravitational force on Earth is one of the major environmental factors affecting plant growth and development. Spacecraft and the International Space Station (ISS), and a three-dimensional (3-D) clinostat have been available to clarify the effects of gravistimulation on plant growth and development in space and on ground conditions, respectively. Under a stimulus-free environment such as space conditions, plants show a growth and developmental habit designated as 'automorphosis' or 'automorphogenesis'. Recent studies in hormonal physiology, together with space and molecular biology, have demonstrated the close relationships between automorphosis and polar auxin transport. Reduced polar auxin transport in space conditions, or induced by the application of polar auxin transport inhibitors, substantially induced automorphosis or automorphosis-like growth and development, indicating that polar auxin transport is responsible for graviresponse in plants. This concise review covers graviresponse in plants and automorphosis observed in space conditions, and polar auxin transport related to graviresponse in etiolated Alaska and ageotropum pea seedlings. Molecular aspects of polar auxin transport clarified in recent studies are also described.
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Affiliation(s)
- J Ueda
- Graduate School of Science, Osaka Prefecture University, Naka-ku, Sakai, Osaka, Japan
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112
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Pan IC, Schmidt W. Functional implications of K63-linked ubiquitination in the iron deficiency response of Arabidopsis roots. FRONTIERS IN PLANT SCIENCE 2014; 4:542. [PMID: 24427162 PMCID: PMC3877749 DOI: 10.3389/fpls.2013.00542] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Accepted: 12/12/2013] [Indexed: 05/02/2023]
Abstract
Iron is an essential micronutrient that plays important roles as a redox cofactor in a variety of processes, many of which are related to DNA metabolism. The E2 ubiquitin conjugase UBC13, the only E2 protein that is capable of catalyzing the formation of non-canonical K63-linked ubiquitin chains, has been associated with the DNA damage tolerance pathway in eukaryotes, critical for maintenance of genome stability and integrity. We previously showed that UBC13 and an interacting E3 ubiquitin ligase, RGLG, affect the differentiation of root epidermal cells in Arabidopsis. When grown on iron-free media, Arabidopsis plants develops root hairs that are branched at their base, a response that has been interpreted as an adaption to reduced iron availability. Mutations in UBC13A abolished the branched root hair phenotype. Unexpectedly, mutations in RGLG genes caused constitutive root hair branching. Based on recent results that link endocytotic turnover of plasma membrane-bound PIN transporters to K63-linked ubiquitination, we reinterpreted our results in a context that classifies the root hair phenotype of iron-deficient plants as a consequence of altered auxin distribution. We show here that UBC13A/B and RGLG1/2 are involved in DNA damage repair and hypothesize that UBC13 protein becomes limited under iron-deficient conditions to prioritize DNA metabolism. The data suggest that genes involved in combating detrimental effects on genome stability may represent essential components in the plant's stress response.
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Affiliation(s)
- I-Chun Pan
- Institute of Plant and Microbial Biology, Academia SinicaTaipei, Taiwan
| | - Wolfgang Schmidt
- Institute of Plant and Microbial Biology, Academia SinicaTaipei, Taiwan
- Biotechnology Center, National Chung-Hsing UniversityTaichung, Taiwan
- Genome and Systems Biology Degree Program, College of Life Science, National Taiwan UniversityTaipei, Taiwan
- *Correspondence: Wolfgang Schmidt, Institute of Plant and Microbial Biology, Academia Sinica, Academia Road 128, Taipei 11529, Taiwan e-mail:
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113
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Robinson DG, Pimpl P. Receptor-mediated transport of vacuolar proteins: a critical analysis and a new model. PROTOPLASMA 2014; 251:247-64. [PMID: 24019013 DOI: 10.1007/s00709-013-0542-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Accepted: 08/20/2013] [Indexed: 05/20/2023]
Abstract
In this article we challenge the widely accepted view that receptors for soluble vacuolar proteins (VSRs) bind to their ligands at the trans-Golgi network (TGN) and transport this cargo via clathrin-coated vesicles (CCV) to a multivesicular prevacuolar compartment. This notion, which we term the "classical model" for vacuolar protein sorting, further assumes that low pH in the prevacuolar compartment causes VSR-ligand dissociation, resulting in a retromer-mediated retrieval of the VSRs to the TGN. We have carefully evaluated the literature with respect to morphology and function of the compartments involved, localization of key components of the sorting machinery, and conclude that there is little direct evidence in its favour. Firstly, unlike mammalian cells where the sorting receptor for lysosomal hydrolases recognizes its ligand in the TGN, the available data suggests that in plants VSRs interact with vacuolar cargo ligands already in the endoplasmic reticulum. Secondly, the evidence supporting the packaging of VSR-ligand complexes into CCV at the TGN is not conclusive. Thirdly, the prevacuolar compartment appears to have a pH unsuitable for VSR-ligand dissociation and lacks the retromer core and the sorting nexins needed for VSR recycling. We present an alternative model for protein sorting in the TGN that draws attention to the much overlooked role of Ca(2+) in VSR-ligand interactions and which may possibly also be a factor in the sequestration of secretory proteins.
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Affiliation(s)
- David G Robinson
- Centre for Organismal Studies (COS), University of Heidelberg, Heidelberg, Germany
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114
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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: 47] [Impact Index Per Article: 4.3] [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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115
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Czyzewicz N, Yue K, Beeckman T, De Smet I. Message in a bottle: small signalling peptide outputs during growth and development. JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:5281-96. [PMID: 24014870 DOI: 10.1093/jxb/ert283] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Classical and recently found phytohormones play an important role in plant growth and development, but plants additionally control these processes through small signalling peptides. Over 1000 potential small signalling peptide sequences are present in the Arabidopsis genome. However, to date, a mere handful of small signalling peptides have been functionally characterized and few have been linked to a receptor. Here, we assess the potential small signalling peptide outputs, namely the molecular, biochemical, and morphological changes they trigger in Arabidopsis. However, we also include some notable studies in other plant species, in order to illustrate the varied effects that can be induced by small signalling peptides. In addition, we touch on some evolutionary aspects of small signalling peptides, as studying their signalling outputs in single-cell green algae and early land plants will assist in our understanding of more complex land plants. Our overview illustrates the growing interest in the small signalling peptide research area and its importance in deepening our understanding of plant growth and development.
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Affiliation(s)
- Nathan Czyzewicz
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire LE12 5RD, UK
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Robert HS, Grones P, Stepanova AN, Robles LM, Lokerse AS, Alonso JM, Weijers D, Friml J. Local auxin sources orient the apical-basal axis in Arabidopsis embryos. Curr Biol 2013; 23:2506-12. [PMID: 24291089 DOI: 10.1016/j.cub.2013.09.039] [Citation(s) in RCA: 142] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2013] [Revised: 08/06/2013] [Accepted: 09/18/2013] [Indexed: 11/16/2022]
Abstract
Establishment of the embryonic axis foreshadows the main body axis of adults both in plants and in animals, but underlying mechanisms are considered distinct. Plants utilize directional, cell-to-cell transport of the growth hormone auxin to generate an asymmetric auxin response that specifies the embryonic apical-basal axis. The auxin flow directionality depends on the polarized subcellular localization of PIN-FORMED (PIN) auxin transporters. It remains unknown which mechanisms and spatial cues guide cell polarization and axis orientation in early embryos. Herein, we provide conceptually novel insights into the formation of embryonic axis in Arabidopsis by identifying a crucial role of localized tryptophan-dependent auxin biosynthesis. Local auxin production at the base of young embryos and the accompanying PIN7-mediated auxin flow toward the proembryo are required for the apical auxin response maximum and the specification of apical embryonic structures. Later in embryogenesis, the precisely timed onset of localized apical auxin biosynthesis mediates PIN1 polarization, basal auxin response maximum, and specification of the root pole. Thus, the tight spatiotemporal control of distinct local auxin sources provides a necessary, non-cell-autonomous trigger for the coordinated cell polarization and subsequent apical-basal axis orientation during embryogenesis and, presumably, also for other polarization events during postembryonic plant life.
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Affiliation(s)
- Hélène S Robert
- Mendel Centre for Genomics and Proteomics of Plants Systems, Central European Institute of Technology (CEITEC), Masaryk University, 625 00 Brno, Czech Republic; Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB) and Department of Plant Biotechnology and Genetics, Ghent University, 9052 Gent, Belgium
| | - Peter Grones
- Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB) and Department of Plant Biotechnology and Genetics, Ghent University, 9052 Gent, Belgium; Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria
| | - Anna N Stepanova
- Department of Genetics, North Carolina State University, Raleigh, NC 27695, USA
| | - Linda M Robles
- Department of Genetics, North Carolina State University, Raleigh, NC 27695, USA
| | - Annemarie S Lokerse
- Laboratory of Biochemistry, Wageningen University, 6703 HA Wageningen, the Netherlands
| | - Jose M Alonso
- Department of Genetics, North Carolina State University, Raleigh, NC 27695, USA
| | - Dolf Weijers
- Laboratory of Biochemistry, Wageningen University, 6703 HA Wageningen, the Netherlands
| | - Jiří Friml
- Mendel Centre for Genomics and Proteomics of Plants Systems, Central European Institute of Technology (CEITEC), Masaryk University, 625 00 Brno, Czech Republic; Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB) and Department of Plant Biotechnology and Genetics, Ghent University, 9052 Gent, Belgium; Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria.
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117
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Sasayama D, Ganguly A, Park M, Cho HT. The M3 phosphorylation motif has been functionally conserved for intracellular trafficking of long-looped PIN-FORMEDs in the Arabidopsis root hair cell. BMC PLANT BIOLOGY 2013; 13:189. [PMID: 24274232 PMCID: PMC4222813 DOI: 10.1186/1471-2229-13-189] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 11/21/2013] [Indexed: 05/22/2023]
Abstract
BACKGROUND PIN-FORMED (PIN) efflux carriers contribute to polar auxin transport and plant development by exhibiting dynamic and diverse asymmetrical localization patterns in the plasma membrane (PM). Phosphorylation of the central hydrophilic loop (HL) of PINs has been implicated in the regulation of PIN trafficking. Recently, we reported that a phosphorylatable motif (M3) in the PIN3-HL is necessary for the polarity, intracellular trafficking, and biological functions of PIN3. In this study, using the root hair system for PIN activity assay, we investigated whether this motif has been functionally conserved among long-HL PINs. RESULTS Root hair-specific overexpression of wild-type PIN1, 2, or 7 greatly inhibited root hair growth by depleting auxin levels in the root hair cell, whereas overexpression of M3 phosphorylation-defective PIN mutants failed to inhibit root hair growth. Consistent with this root hair phenotype, the PM localization of M3 phosphorylation-defective PIN1 and PIN7 was partially disrupted, resulting in less auxin efflux and restoration of root hair growth. Partial formation of brefeldin A-compartments in these phosphorylation-mutant PIN lines also suggested that their PM targeting was partially disrupted. On the other hand, compared with the PIN1 and PIN7 mutant proteins, M3-phosphorylation-defective PIN2 proteins were almost undetectable. However, the mutant PIN2 protein levels were restored by wortmannin treatment almost to the wild-type PIN2 level, indicating that the M3 motif of PIN2, unlike that of other PINs, is implicated in PIN2 trafficking to the vacuolar lytic pathway. CONCLUSIONS These results suggest that the M3 phosphorylation motif has been functionally conserved to modulate the intracellular trafficking of long-HL PINs, but its specific function in trafficking has diverged among PIN members.
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Affiliation(s)
- Daisuke Sasayama
- Department of Biological Sciences and Plant Genomics and Breeding Institute, Seoul National University, Seoul 151-742, Korea
- Organization of Advanced Science and Technology, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe, Hyogo 657-8501, Japan
| | - Anindya Ganguly
- Department of Biological Sciences and Plant Genomics and Breeding Institute, Seoul National University, Seoul 151-742, Korea
- Current address, Department of Biology, Washington University, 1 Brookings Drive, Saint Louis, MO 63130, USA
| | - Minho Park
- Department of Biological Sciences and Plant Genomics and Breeding Institute, Seoul National University, Seoul 151-742, Korea
| | - Hyung-Taeg Cho
- Department of Biological Sciences and Plant Genomics and Breeding Institute, Seoul National University, Seoul 151-742, Korea
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118
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Abbas M, Alabadí D, Blázquez MA. Differential growth at the apical hook: all roads lead to auxin. FRONTIERS IN PLANT SCIENCE 2013; 4:441. [PMID: 24204373 PMCID: PMC3817370 DOI: 10.3389/fpls.2013.00441] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 10/15/2013] [Indexed: 05/18/2023]
Abstract
The apical hook is a developmentally regulated structure that appears in dicotyledonous seedlings when seeds germinate buried in the soil. It protects the shoot apical meristem and cotyledons from damage while the seedling is pushing upwards seeking for light, and it is formed by differential cell expansion between both sides of the upper part of the hypocotyl. Its apparent simplicity and the fact that it is dispensable when seedlings are grown in vitro have converted the apical hook in one of the favorite experimental models to study the regulation of differential growth. The involvement of hormones -especially auxin-in this process was manifested already in the early studies. Remarkably, a gradient of this hormone across the hook curvature is instrumental to complete its development, similar to what has been proposed for other processes involving the bending of an organ, such as tropic responses. In agreement with this, other hormones-mainly gibberellins and ethylene-and the light, regulate in a timely and interconnected manner the auxin gradient to promote hook development and its opening, respectively. Here, we review the latest findings obtained mainly with the apical hook of Arabidopsis thaliana, paying special attention to the molecular mechanisms for the cross-regulation between the different hormone signaling pathways that underlie this developmental process.
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Affiliation(s)
| | - David Alabadí
- *Correspondence: David Alabadí, Instituto de Biología Molecular y Celular de Plantas, Universitat Politècnica de València - Consejo Superior de Investigaciones Científicas, Edificio E8, Ingeniero Fausto Elio s/n, Valencia, 46022, Spain e-mail:
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Mudgil Y, Ghawana S, Jones AM. N-MYC down-regulated-like proteins regulate meristem initiation by modulating auxin transport and MAX2 expression. PLoS One 2013; 8:e77863. [PMID: 24223735 PMCID: PMC3817199 DOI: 10.1371/journal.pone.0077863] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Accepted: 09/14/2013] [Indexed: 11/27/2022] Open
Abstract
Background N-MYC DOWN-REGULATED-LIKE (NDL) proteins interact with the Gβ subunit (AGB1) of the heterotrimeric G protein complex and play an important role in AGB1-dependent regulation of lateral root formation by affecting root auxin transport, auxin gradients and the steady-state levels of mRNA encoding the PIN-FORMED 2 and AUXIN 1 auxin transport facilitators. Auxin transport in aerial tissue follows different paths and utilizes different transporters than in roots; therefore, in the present study, we analyzed whether NDL proteins play an important role in AGB1-dependent, auxin-mediated meristem development. Methodology/Principal Findings Expression levels of NDL gene family members need to be tightly regulated, and altered expression (both over-expression and down-regulation) confers ectopic growth. Over-expression of NDL1 disrupts vegetative and reproductive organ development. Reduced expression of the NDL gene family members results in asymmetric leaf emergence, twinning of rosette leaves, defects in leaf formation, and abnormal silique distribution. Reduced expression of the NDL genes in the agb1-2 (null allele) mutant rescues some of the abnormal phenotypes, such as silique morphology, silique distribution, and peduncle angle, suggesting that proper levels of NDL proteins are maintained by AGB1. We found that all of these abnormal aerial phenotypes due to altered NDL expression were associated with increases in basipetal auxin transport, altered auxin maxima and altered MAX2 expression within the inflorescence stem. Conclusion/Significance NDL proteins, together with AGB1, act as positive regulators of meristem initiation and branching. AGB1 and NDL1 positively regulate basipetal inflorescence auxin transport and modulate MAX2 expression in shoots, which in turn regulates organ and lateral meristem formation by the establishment and maintenance of auxin gradients.
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Affiliation(s)
- Yashwanti Mudgil
- Department of Botany, University of Delhi, Delhi, India
- * E-mail:
| | | | - Alan M. Jones
- Departments of Biology and Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
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120
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Vanneste S, Friml J. Calcium: The Missing Link in Auxin Action. PLANTS (BASEL, SWITZERLAND) 2013; 2:650-75. [PMID: 27137397 PMCID: PMC4844386 DOI: 10.3390/plants2040650] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 10/07/2013] [Accepted: 10/10/2013] [Indexed: 01/18/2023]
Abstract
Due to their sessile lifestyles, plants need to deal with the limitations and stresses imposed by the changing environment. Plants cope with these by a remarkable developmental flexibility, which is embedded in their strategy to survive. Plants can adjust their size, shape and number of organs, bend according to gravity and light, and regenerate tissues that were damaged, utilizing a coordinating, intercellular signal, the plant hormone, auxin. Another versatile signal is the cation, Ca(2+), which is a crucial second messenger for many rapid cellular processes during responses to a wide range of endogenous and environmental signals, such as hormones, light, drought stress and others. Auxin is a good candidate for one of these Ca(2+)-activating signals. However, the role of auxin-induced Ca(2+) signaling is poorly understood. Here, we will provide an overview of possible developmental and physiological roles, as well as mechanisms underlying the interconnection of Ca(2+) and auxin signaling.
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Affiliation(s)
- Steffen Vanneste
- Plant Systems Biology, VIB, and Plant Biotechnology and Bio-informatics, Ghent University, Ghent 9052, Belgium.
| | - Jiří Friml
- Plant Systems Biology, VIB, and Plant Biotechnology and Bio-informatics, Ghent University, Ghent 9052, Belgium
- Institute of Science and Technology Austria (IST Austria), Klosterneuburg 3400, Austria
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121
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A role for a dioxygenase in auxin metabolism and reproductive development in rice. Dev Cell 2013; 27:113-22. [PMID: 24094741 DOI: 10.1016/j.devcel.2013.09.005] [Citation(s) in RCA: 137] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2012] [Revised: 06/27/2013] [Accepted: 09/06/2013] [Indexed: 12/28/2022]
Abstract
Indole-3-acetic acid (IAA), the natural auxin in plants, regulates many aspects of plant growth and development. Extensive analyses have elucidated the components of auxin biosynthesis, transport, and signaling, but the physiological roles and molecular mechanisms of auxin degradation remain elusive. Here, we demonstrate that the dioxygenase for auxin oxidation (DAO) gene, encoding a putative 2-oxoglutarate-dependent-Fe (II) dioxygenase, is essential for anther dehiscence, pollen fertility, and seed initiation in rice. Rice mutant lines lacking a functional DAO display increased levels of free IAA in anthers and ovaries. Furthermore, exogenous application of IAA or overexpression of the auxin biosynthesis gene OsYUCCA1 phenocopies the dao mutants. We show that recombinant DAO converts the active IAA into biologically inactive 2-oxoindole-3-acetic acid (OxIAA) in vitro. Collectively, these data support a key role of DAO in auxin catabolism and maintenance of auxin homeostasis central to plant reproductive development.
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122
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Offringa R, Kleine-Vehn J. Cell polarity and development. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2013; 55:786-8. [PMID: 23953999 DOI: 10.1111/jipb.12099] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Affiliation(s)
- Remko Offringa
- Molecular and Developmental Genetics, Institute Biology Leiden, Leiden University, Sylvius Laboratory, Sylviusweg 72, 2333, BE, The Netherlands.
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123
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Kim SY, Xu ZY, Song K, Kim DH, Kang H, Reichardt I, Sohn EJ, Friml J, Juergens G, Hwang I. Adaptor protein complex 2-mediated endocytosis is crucial for male reproductive organ development in Arabidopsis. THE PLANT CELL 2013; 25:2970-85. [PMID: 23975898 PMCID: PMC3784592 DOI: 10.1105/tpc.113.114264] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 07/15/2013] [Accepted: 08/06/2013] [Indexed: 05/18/2023]
Abstract
Fertilization in flowering plants requires the temporal and spatial coordination of many developmental processes, including pollen production, anther dehiscence, ovule production, and pollen tube elongation. However, it remains elusive as to how this coordination occurs during reproduction. Here, we present evidence that endocytosis, involving heterotetrameric adaptor protein complex 2 (AP-2), plays a crucial role in fertilization. An Arabidopsis thaliana mutant ap2m displays multiple defects in pollen production and viability, as well as elongation of staminal filaments and pollen tubes, all of which are pivotal processes needed for fertilization. Of these abnormalities, the defects in elongation of staminal filaments and pollen tubes were partially rescued by exogenous auxin. Moreover, DR5rev:GFP (for green fluorescent protein) expression was greatly reduced in filaments and anthers in ap2m mutant plants. At the cellular level, ap2m mutants displayed defects in both endocytosis of N-(3-triethylammonium-propyl)-4-(4-diethylaminophenylhexatrienyl) pyridinium dibromide, a lypophilic dye used as an endocytosis marker, and polar localization of auxin-efflux carrier PIN FORMED2 (PIN2) in the stamen filaments. Moreover, these defects were phenocopied by treatment with Tyrphostin A23, an inhibitor of endocytosis. Based on these results, we propose that AP-2-dependent endocytosis plays a crucial role in coordinating the multiple developmental aspects of male reproductive organs by modulating cellular auxin level through the regulation of the amount and polarity of PINs.
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Affiliation(s)
- Soo Youn Kim
- Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Zheng-Yi Xu
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Kyungyoung Song
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Dae Heon Kim
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Hyangju Kang
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Ilka Reichardt
- Developmental Genetics, Center for Plant Molecular Biology (Zentrum fur Molekularbiologie der Pflanzen), University of Tuebingen, 72076 Tuebingen, Germany
| | - Eun Ju Sohn
- Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Jiří Friml
- Department of Plant Systems Biology, Flamders Institute for Biotechnology (VIB), and Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium
- Institute of Science and Technology, A-3400 Klosterneuburg, Austria
| | - Gerd Juergens
- Developmental Genetics, Center for Plant Molecular Biology (Zentrum fur Molekularbiologie der Pflanzen), University of Tuebingen, 72076 Tuebingen, Germany
| | - Inhwan Hwang
- Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang 790-784, Korea
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea
- Address correspondence to
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Cazzonelli CI, Vanstraelen M, Simon S, Yin K, Carron-Arthur A, Nisar N, Tarle G, Cuttriss AJ, Searle IR, Benkova E, Mathesius U, Masle J, Friml J, Pogson BJ. Role of the Arabidopsis PIN6 auxin transporter in auxin homeostasis and auxin-mediated development. PLoS One 2013; 8:e70069. [PMID: 23922907 PMCID: PMC3726503 DOI: 10.1371/journal.pone.0070069] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Accepted: 06/15/2013] [Indexed: 01/11/2023] Open
Abstract
Plant-specific PIN-formed (PIN) efflux transporters for the plant hormone auxin are required for tissue-specific directional auxin transport and cellular auxin homeostasis. The Arabidopsis PIN protein family has been shown to play important roles in developmental processes such as embryogenesis, organogenesis, vascular tissue differentiation, root meristem patterning and tropic growth. Here we analyzed roles of the less characterised Arabidopsis PIN6 auxin transporter. PIN6 is auxin-inducible and is expressed during multiple auxin-regulated developmental processes. Loss of pin6 function interfered with primary root growth and lateral root development. Misexpression of PIN6 affected auxin transport and interfered with auxin homeostasis in other growth processes such as shoot apical dominance, lateral root primordia development, adventitious root formation, root hair outgrowth and root waving. These changes in auxin-regulated growth correlated with a reduction in total auxin transport as well as with an altered activity of DR5-GUS auxin response reporter. Overall, the data indicate that PIN6 regulates auxin homeostasis during plant development.
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Affiliation(s)
- Christopher I Cazzonelli
- Australian Research Council Centre of Excellence in Plant Energy Biology, College of Medicine, Biology and Environment, Research School of Biology, The Australian National University, Canberra, Australia.
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125
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Yuan HM, Liu WC, Jin Y, Lu YT. Role of ROS and auxin in plant response to metal-mediated stress. PLANT SIGNALING & BEHAVIOR 2013; 8:e24671. [PMID: 23603941 PMCID: PMC3906317 DOI: 10.4161/psb.24671] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Being unable to move away from their places of germination, in order to avoid excess metal-induced damages, plants have to evolve different strategies and complex regulatory mechanisms to survive harsh conditions. While both ROS and auxin are documented to be important in plant response to metal stress, the mechanisms underlying the crosstalk between ROS and auxin in metal stress are poorly understood. In this review, we provide an update on the regulation of plant responses to metal-stress by ROS and auxin signaling pathways, primarily, with a focus on the copper, aluminum and cadmium stress. We aim at surveying the mechanisms underlying how metal stress modulates the changes in auxin distribution and the network of ROS and auxin in plant response to metal stress based on recent studies.
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126
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Wendrich JR, Weijers D. The Arabidopsis embryo as a miniature morphogenesis model. THE NEW PHYTOLOGIST 2013; 199:14-25. [PMID: 23590679 DOI: 10.1111/nph.12267] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Accepted: 03/12/2013] [Indexed: 05/06/2023]
Abstract
Four basic ingredients of morphogenesis, oriented cell division and expansion, cell-cell communication and cell fate specification allow plant cells to develop into a wide variety of organismal architectures. A central question in plant biology is how these cellular processes are regulated and orchestrated. Here, we present the advantages of the early Arabidopsis embryo as a model for studying the control of morphogenesis. All ingredients of morphogenesis converge during embryogenesis, and the highly predictable nature of embryo development offers unprecedented opportunities for understanding their regulation in time and space. In this review we describe the morphogenetic principles underlying embryo patterning and discuss recent advances in their regulation. Morphogenesis is under tight transcriptional control and most genes that were identified as important regulators of embryo patterning encode transcription factors or components of signaling pathways. There exists, therefore, a large gap between the transcriptional control of embryo morphogenesis and the cellular execution. We describe the first such connections, and propose future directions that should help bridge this gap and generate comprehensive understanding of the control of morphogenesis.
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Affiliation(s)
- Jos R Wendrich
- Laboratory of Biochemistry, Wageningen University, Dreijenlaan 3, 6703HA, Wageningen, the Netherlands
| | - Dolf Weijers
- Laboratory of Biochemistry, Wageningen University, Dreijenlaan 3, 6703HA, Wageningen, the Netherlands
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Abstract
Auxin is a plant hormone involved in an extraordinarily broad variety of biological mechanisms. These range from basic cellular processes, such as endocytosis, cell polarity, and cell cycle control over localized responses such as cell elongation and differential growth, to macroscopic phenomena such as embryogenesis, tissue patterning, and de novo formation of organs. Even though the history of auxin research reaches back more than a hundred years, we are still far from a comprehensive understanding of how auxin governs such a wide range of responses. Some answers to this question may lie in the auxin molecule itself. Naturally occurring auxin-like substances have been found and they may play roles in specific developmental and cellular processes. The molecular mode of auxin action can be further explored by the utilization of synthetic auxin-like molecules. A second area is the perception of auxin, where we know of three seemingly independent receptors and signalling systems, some better understood than others, but each of them probably involved in distinct physiological processes. Lastly, auxin is actively modified, metabolized, and intracellularly compartmentalized, which can have a great impact on its availability and activity. In this review, we will give an overview of these rather recent and emerging areas of auxin research and try to formulate some of the open questions. Without doubt, the manifold facets of auxin biology will not cease to amaze us for a long time to come.
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Affiliation(s)
- Michael Sauer
- Centro Nacional de Biotecnología-CNB-CSIC, Darwin 3, 28049 Madrid, Spain
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128
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Bender RL, Fekete ML, Klinkenberg PM, Hampton M, Bauer B, Malecha M, Lindgren K, A Maki J, Perera MADN, Nikolau BJ, Carter CJ. PIN6 is required for nectary auxin response and short stamen development. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 74:893-904. [PMID: 23551385 DOI: 10.1111/tpj.12184] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Revised: 03/15/2013] [Accepted: 03/20/2013] [Indexed: 05/04/2023]
Abstract
The PIN family of proteins is best known for its involvement in polar auxin transport and tropic responses. PIN6 (At1g77110) is one of the remaining PIN family members in Arabidopsis thaliana to which a biological function has not yet been ascribed. Here we report that PIN6 is a nectary-enriched gene whose expression level is positively correlated with total nectar production in Arabidopsis, and whose function is required for the proper development of short stamens. PIN6 accumulates in internal membranes consistent with the ER, and multiple lines of evidence demonstrate that PIN6 is required for auxin-dependent responses in nectaries. Wild-type plants expressing auxin-responsive DR5:GFP or DR5:GUS reporters displayed intense signal in lateral nectaries, but pin6 lateral nectaries showed little or no signal for these reporters. Further, exogenous auxin treatment increased nectar production more than tenfold in wild-type plants, but nectar production was not increased in pin6 mutants when treated with auxin. Conversely, the auxin transport inhibitor N-1-naphthylphthalamic acid (NPA) reduced nectar production in wild-type plants by more than twofold, but had no significant effect on pin6 lines. Interestingly, a MYB57 transcription factor mutant, myb57-2, closely phenocopied the loss-of-function mutant pin6-2. However, PIN6 expression was not dependent on MYB57, and RNA-seq analyses of pin6-2 and myb57-2 mutant nectaries showed little overlap in terms of differentially expressed genes. Cumulatively, these results demonstrate that PIN6 is required for proper auxin response and nectary function in Arabidopsis. These results also identify auxin as an important factor in the regulation of nectar production, and implicate short stamens in the maturation of lateral nectaries.
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Affiliation(s)
- Ricci L Bender
- Department of Biology, University of Minnesota Duluth, Duluth, MN 55812, USA
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129
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Moschou PN, Smertenko AP, Minina EA, Fukada K, Savenkov EI, Robert S, Hussey PJ, Bozhkov PV. The caspase-related protease separase (extra spindle poles) regulates cell polarity and cytokinesis in Arabidopsis. THE PLANT CELL 2013; 25:2171-86. [PMID: 23898031 PMCID: PMC3723619 DOI: 10.1105/tpc.113.113043] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Vesicle trafficking plays an important role in cell division, establishment of cell polarity, and translation of environmental cues to developmental responses. However, the molecular mechanisms regulating vesicle trafficking remain poorly understood. Here, we report that the evolutionarily conserved caspase-related protease separase (extra spindle poles [ESP]) is required for the establishment of cell polarity and cytokinesis in Arabidopsis thaliana. At the cellular level, separase colocalizes with microtubules and RabA2a (for RAS genes from rat brainA2a) GTPase-positive structures. Separase facilitates polar targeting of the auxin efflux carrier PIN-formed2 (PIN2) to the rootward side of the root cortex cells. Plants with the radially swollen4 (rsw4) allele with compromised separase activity, in addition to mitotic failure, display isotropic cell growth, perturbation of auxin gradient formation, slower gravitropic response in roots, and cytokinetic failure. Measurements of the dynamics of vesicle markers on the cell plate revealed an overall reduction of the delivery rates of KNOLLE and RabA2a GTPase in separase-deficient roots. Furthermore, dissociation of the clathrin light chain, a protein that plays major role in the formation of coated vesicles, was slower in rsw4 than in the control. Our results demonstrate that separase is a key regulator of vesicle trafficking, which is indispensable for cytokinesis and the establishment of cell polarity.
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Affiliation(s)
- Panagiotis N Moschou
- Department of Plant Biology and Forest Genetics, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linean Center for Plant Biology, SE-75007 Uppsala, Sweden.
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Yu H, Karampelias M, Robert S, Peer WA, Swarup R, Ye S, Ge L, Cohen J, Murphy A, Friml J, Estelle M. ROOT ULTRAVIOLET B-SENSITIVE1/weak auxin response3 is essential for polar auxin transport in Arabidopsis. PLANT PHYSIOLOGY 2013; 162:965-76. [PMID: 23580592 PMCID: PMC3668084 DOI: 10.1104/pp.113.217018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The phytohormone auxin regulates virtually every aspect of plant development. To identify new genes involved in auxin activity, a genetic screen was performed for Arabidopsis (Arabidopsis thaliana) mutants with altered expression of the auxin-responsive reporter DR5rev:GFP. One of the mutants recovered in the screen, designated as weak auxin response3 (wxr3), exhibits much lower DR5rev:GFP expression when treated with the synthetic auxin 2,4-dichlorophenoxyacetic acid and displays severe defects in root development. The wxr3 mutant decreases polar auxin transport and results in a disruption of the asymmetric auxin distribution. The levels of the auxin transporters AUXIN1 and PIN-FORMED are dramatically reduced in the wxr3 root tip. Molecular analyses demonstrate that WXR3 is ROOT ULTRAVIOLET B-SENSITIVE1 (RUS1), a member of the conserved Domain of Unknown Function647 protein family found in diverse eukaryotic organisms. Our data suggest that RUS1/WXR3 plays an essential role in the regulation of polar auxin transport by maintaining the proper level of auxin transporters on the plasma membrane.
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131
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Cell polarity and patterning by PIN trafficking through early endosomal compartments in Arabidopsis thaliana. PLoS Genet 2013; 9:e1003540. [PMID: 23737757 PMCID: PMC3667747 DOI: 10.1371/journal.pgen.1003540] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 04/16/2013] [Indexed: 01/15/2023] Open
Abstract
PIN-FORMED (PIN) proteins localize asymmetrically at the plasma membrane and mediate intercellular polar transport of the plant hormone auxin that is crucial for a multitude of developmental processes in plants. PIN localization is under extensive control by environmental or developmental cues, but mechanisms regulating PIN localization are not fully understood. Here we show that early endosomal components ARF GEF BEN1 and newly identified Sec1/Munc18 family protein BEN2 are involved in distinct steps of early endosomal trafficking. BEN1 and BEN2 are collectively required for polar PIN localization, for their dynamic repolarization, and consequently for auxin activity gradient formation and auxin-related developmental processes including embryonic patterning, organogenesis, and vasculature venation patterning. These results show that early endosomal trafficking is crucial for cell polarity and auxin-dependent regulation of plant architecture. Auxin is a unique plant hormone, which is actively and directionally transported in plant tissues. Transported auxin locally accumulates in the plant body and triggers a multitude of responses, including organ formation and patterning. Therefore, regulation of the directional auxin transport is very important in multiple aspects of plant development. The PIN-FORMED (PIN) family of auxin transporters is known to localize at specific sides of cells and export auxin from the cells, enabling the directional transport of auxin in the tissues. PIN proteins are rapidly shuttling between the plasma membrane and intracellular compartments, potentially allowing dynamic changes of the asymmetric localization according to developmental and environmental cues. Here, we discovered that a mutation in the Sec1/Munc18 family protein VPS45 abolishes its own early endosomal localization and compromises intracellular trafficking of PIN proteins. By genetic and pharmacological inhibition of early endosomal trafficking, we also revealed that another early endosomal protein, ARF GEF BEN1, is involved in early endosomal trafficking at a distinct step. Furthermore, we showed that these components play crucial roles in polar localization and dynamic repolarization of PIN proteins, which underpin various developmental processes. These findings highlight the indispensable roles of early endosomal components in regulating PIN polarity and plant architecture.
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Martin MV, Fiol DF, Sundaresan V, Zabaleta EJ, Pagnussat GC. oiwa, a female gametophytic mutant impaired in a mitochondrial manganese-superoxide dismutase, reveals crucial roles for reactive oxygen species during embryo sac development and fertilization in Arabidopsis. THE PLANT CELL 2013; 25:1573-91. [PMID: 23653473 PMCID: PMC3694693 DOI: 10.1105/tpc.113.109306] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Reactive oxygen species (ROS) can function as signaling molecules, regulating key aspects of plant development, or as toxic compounds leading to oxidative damage. In this article, we show that the regulation of ROS production during megagametogenesis is largely dependent on MSD1, a mitochondrial Mn-superoxide dismutase. Wild-type mature embryo sacs show ROS exclusively in the central cell, which appears to be the main source of ROS before pollination. Accordingly, MSD1 shows a complementary expression pattern. MSD1 expression is elevated in the egg apparatus at maturity but is downregulated in the central cell. The oiwa mutants are characterized by high levels of ROS detectable in both the central cell and the micropylar cells. Remarkably, egg apparatus cells in oiwa show central cell features, indicating that high levels of ROS result in the expression of central cell characteristic genes. Notably, ROS are detected in synergid cells after pollination. This ROS burst depends on stigma pollination but precedes fertilization, suggesting that embryo sacs sense the imminent arrival of pollen tubes and respond by generating an oxidative environment. Altogether, we show that ROS play a crucial role during female gametogenesis and fertilization. MSD1 activity seems critical for maintaining ROS localization and important for embryo sac patterning.
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Affiliation(s)
- María Victoria Martin
- Instituto de Investigaciones Biológicas IIB-Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional de Mar del Plata, 7600 Mar del Plata, Argentina
| | - Diego Fernando Fiol
- Instituto de Investigaciones Biológicas IIB-Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional de Mar del Plata, 7600 Mar del Plata, Argentina
| | - Venkatesan Sundaresan
- Department of Plant Biology, University of California, Davis, California 95616
- Department of Plant Sciences, University of California, Davis, California 95616
| | - Eduardo Julián Zabaleta
- Instituto de Investigaciones Biológicas IIB-Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional de Mar del Plata, 7600 Mar del Plata, Argentina
| | - Gabriela Carolina Pagnussat
- Instituto de Investigaciones Biológicas IIB-Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional de Mar del Plata, 7600 Mar del Plata, Argentina
- Address correspondence to
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133
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Rigó G, Ayaydin F, Tietz O, Zsigmond L, Kovács H, Páy A, Salchert K, Darula Z, Medzihradszky KF, Szabados L, Palme K, Koncz C, Cséplő Á. Inactivation of plasma membrane-localized CDPK-RELATED KINASE5 decelerates PIN2 exocytosis and root gravitropic response in Arabidopsis. THE PLANT CELL 2013; 25:1592-608. [PMID: 23673979 PMCID: PMC3694694 DOI: 10.1105/tpc.113.110452] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Revised: 04/17/2013] [Accepted: 04/26/2013] [Indexed: 05/19/2023]
Abstract
CRK5 is a member of the Arabidopsis thaliana Ca(2+)/calmodulin-dependent kinase-related kinase family. Here, we show that inactivation of CRK5 inhibits primary root elongation and delays gravitropic bending of shoots and roots. Reduced activity of the auxin-induced DR5-green fluorescent protein reporter suggests that auxin is depleted from crk5 root tips. However, no tip collapse is observed and the transcription of genes for auxin biosynthesis, AUXIN TRANSPORTER/AUXIN TRANSPORTER-LIKE PROTEIN (AUX/LAX) auxin influx, and PIN-FORMED (PIN) efflux carriers is unaffected by the crk5 mutation. Whereas AUX1, PIN1, PIN3, PIN4, and PIN7 display normal localization, PIN2 is depleted from apical membranes of epidermal cells and shows basal to apical relocalization in the cortex of the crk5 root transition zone. This, together with an increase in the number of crk5 lateral root primordia, suggests facilitated auxin efflux through the cortex toward the elongation zone. CRK5 is a plasma membrane-associated kinase that forms U-shaped patterns facing outer lateral walls of epidermis and cortex cells. Brefeldin inhibition of exocytosis stimulates CRK5 internalization into brefeldin bodies. CRK5 phosphorylates the hydrophilic loop of PIN2 in vitro, and PIN2 shows accelerated accumulation in brefeldin bodies in the crk5 mutant. Delayed gravitropic response of the crk5 mutant thus likely reflects defective phosphorylation of PIN2 and deceleration of its brefeldin-sensitive membrane recycling.
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Affiliation(s)
- Gábor Rigó
- Institute of Plant Biology, Biological Research Center, H-6726 Szeged, Hungary
| | - Ferhan Ayaydin
- Institute of Plant Biology, Biological Research Center, H-6726 Szeged, Hungary
| | - Olaf Tietz
- Institute of Biology II/Molecular Plant Physiology, Faculty of Biology, Albert-Ludwigs-University of Freiburg, D-79104 Freiburg, Germany
| | - Laura Zsigmond
- Institute of Plant Biology, Biological Research Center, H-6726 Szeged, Hungary
- Department of Plant Biology, University of Szeged, H-6726 Szeged, Hungary
| | - Hajnalka Kovács
- Institute of Plant Biology, Biological Research Center, H-6726 Szeged, Hungary
| | - Anikó Páy
- Institute of Plant Biology, Biological Research Center, H-6726 Szeged, Hungary
| | - Klaus Salchert
- BASF Plant Science, DNA Landmarks, Quebec J3B 6X3, Canada
| | - Zsuzsanna Darula
- Laboratory of Proteomics Research, Biological Research Center of the Hungarian Academy of Sciences, H-6726 Szeged, Hungary
| | - Katalin F. Medzihradszky
- Laboratory of Proteomics Research, Biological Research Center of the Hungarian Academy of Sciences, H-6726 Szeged, Hungary
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94158
| | - László Szabados
- Institute of Plant Biology, Biological Research Center, H-6726 Szeged, Hungary
| | - Klaus Palme
- Institute of Biology II/Molecular Plant Physiology, Faculty of Biology, Albert-Ludwigs-University of Freiburg, D-79104 Freiburg, Germany
| | - Csaba Koncz
- Institute of Plant Biology, Biological Research Center, H-6726 Szeged, Hungary
- Max-Planck Institute für Züchtungschforshung, D-50829 Cologne, Germany
- Address correspondence to
| | - Ágnes Cséplő
- Institute of Plant Biology, Biological Research Center, H-6726 Szeged, Hungary
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134
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Jásik J, Boggetti B, Baluška F, Volkmann D, Gensch T, Rutten T, Altmann T, Schmelzer E. PIN2 turnover in Arabidopsis root epidermal cells explored by the photoconvertible protein Dendra2. PLoS One 2013; 8:e61403. [PMID: 23637828 PMCID: PMC3630207 DOI: 10.1371/journal.pone.0061403] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 03/10/2013] [Indexed: 11/18/2022] Open
Abstract
The steady state level of integral membrane proteins is dependent on a strictly controlled delivery and removal. Here we show that Dendra2, a green-to-red photoconvertible fluorescent protein, is a suitable tool to study protein turnover in plants. We characterized the fluorescence properties of Dendra2 expressed either as a free protein or as a tag in Arabidopsis thaliana roots and optimized photoconversion settings to study protein turnover. Dendra2 was fused to the PIN2 protein, an auxin transporter in the root tip, and by time-lapse imaging and assessment of red and green signal intensities in the membrane after photoconversion we quantified directly and simultaneously the rate of PIN2 delivery of the newly synthesized protein into the plasma membrane as well as the disappearance of the protein from the plasma membrane due to degradation. Additionally we have verified several factors which are expected to affect PIN2 protein turnover and therefore potentially regulate root growth.
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Affiliation(s)
- Ján Jásik
- Max Planck Institute for Plant Breeding Research, Köln, Germany.
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135
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Yoshida S, Saiga S, Weijers D. Auxin regulation of embryonic root formation. PLANT & CELL PHYSIOLOGY 2013; 54:325-32. [PMID: 23220820 DOI: 10.1093/pcp/pcs170] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The plant hormone auxin was initially identified as the bioactive substance that induces roots in plant tissue culture. In the past decades, mechanisms for auxin action, including its transport and response, have been described in detail. However, a molecular and cellular description of its role in root initiation is far from complete. In this review, we discuss recent advances in our understanding of auxin-dependent embryonic root formation. During this process, a root meristem is initiated in a precise and predictable position, and at a stage when the organism consists of relatively few cells. Recent studies have revealed mechanisms for local control of auxin transport, for cellular differences in auxin response components and cell type-specific chromatin regulation. The recent identification of biologically relevant target genes for auxin regulation during embryonic root initiation now also allows dissection of auxin-activated cellular processes. Finally, we discuss the potential for hormonal cross-regulation in embryonic root formation.
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Affiliation(s)
- Saiko Yoshida
- Laboratory of Biochemistry, Wageningen University, Dreijenlaan 3, 6703 HA Wageningen, The Netherlands
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136
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Abstract
The precise arrangement of plant organs, also called phyllotaxis, has fascinated scientists from multiple disciplines. Whereas early work focused on morphological observations of phyllotaxis, recent findings have started to reveal the mechanisms behind this process, showing how molecular regulation and biochemical gradients interact with physical components to generate such precise patterns of growth. Here, I review new insights into the regulation of phyllotactic patterning and provide an overview of the various factors that can drive these robust growth patterns.
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Affiliation(s)
- Jan Traas
- Laboratoire de Reproduction et Développement des Plantes, 46 allée d'Italie, 69364 Lyon, Cedex 07, France.
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137
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Asymmetric gibberellin signaling regulates vacuolar trafficking of PIN auxin transporters during root gravitropism. Proc Natl Acad Sci U S A 2013; 110:3627-32. [PMID: 23391733 DOI: 10.1073/pnas.1300107110] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Gravitropic bending of plant organs is mediated by an asymmetric signaling of the plant hormone auxin between the upper and lower side of the respective organ. Here, we show that also another plant hormone, gibberellic acid (GA), shows asymmetric action during gravitropic responses. Immunodetection using an antibody against GA and monitoring GA signaling output by downstream degradation of DELLA proteins revealed an asymmetric GA distribution and response with the maximum at the lower side of gravistimulated roots. Genetic or pharmacological manipulation of GA levels or response affects gravity-mediated auxin redistribution and root bending response. The higher GA levels at the lower side of the root correlate with increased amounts of PIN-FORMED2 (PIN2) auxin transporter at the plasma membrane. The observed increase in PIN2 stability is caused by a specific GA effect on trafficking of PIN proteins to lytic vacuoles that presumably occurs downstream of brefeldin A-sensitive endosomes. Our results suggest that asymmetric auxin distribution instructive for gravity-induced differential growth is consolidated by the asymmetric action of GA that stabilizes the PIN-dependent auxin stream along the lower side of gravistimulated roots.
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138
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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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139
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Oliva M, Farcot E, Vernoux T. Plant hormone signaling during development: insights from computational models. CURRENT OPINION IN PLANT BIOLOGY 2013; 16:19-24. [PMID: 23219863 DOI: 10.1016/j.pbi.2012.11.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Revised: 11/09/2012] [Accepted: 11/13/2012] [Indexed: 05/23/2023]
Abstract
Recent years have seen an impressive increase in our knowledge of the topology of plant hormone signaling networks. The complexity of these topologies has motivated the development of models for several hormones to aid understanding of how signaling networks process hormonal inputs. Such work has generated essential insights into the mechanisms of hormone perception and of regulation of cellular responses such as transcription in response to hormones. In addition, modeling approaches have contributed significantly to exploring how spatio-temporal regulation of hormone signaling contributes to plant growth and patterning. New tools have also been developed to obtain quantitative information on hormone distribution during development and to test model predictions, opening the way for quantitative understanding of the developmental roles of hormones.
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Affiliation(s)
- Marina Oliva
- Laboratoire de Reproduction et Développement des Plantes, CNRS, INRA, ENS Lyon, UCBL, Université de Lyon, 46 Allée d'Italie, 69364 Lyon Cedex 07, France
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140
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Barbez E, Kleine-Vehn J. Divide Et Impera--cellular auxin compartmentalization. CURRENT OPINION IN PLANT BIOLOGY 2013. [PMID: 23200033 DOI: 10.1016/j.pbi.2012.10.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The phytohormone auxin is an essential regulator for plant growth and development. Decades of intensive research revealed the mutual importance of auxin metabolism and intercellular cell-to-cell transport for the regulation of spatiotemporal auxin distribution. Just recently, intracellular putative auxin carriers, such as the PIN-FORMED (PIN)5/PIN8 and the PIN-LIKES (PILS)2/PILS5 were discovered at the endoplasmic reticulum (ER) and seem to limit nuclear auxin signaling via an auxin sequestration mechanism. Moreover, these auxin carriers at the ER might provide a link between auxin compartmentalization and auxin conjugation-based metabolism. Here we review the recent findings on auxin compartmentalization at the ER and discuss its potential contribution to cellular auxin homeostasis and its importance for plant development.
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Affiliation(s)
- Elke Barbez
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna (BOKU), 1190 Vienna, Austria
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141
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Gillaspy GE. The Role of Phosphoinositides and Inositol Phosphates in Plant Cell Signaling. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 991:141-57. [DOI: 10.1007/978-94-007-6331-9_8] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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142
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Blancaflor EB. Regulation of plant gravity sensing and signaling by the actin cytoskeleton. AMERICAN JOURNAL OF BOTANY 2013; 100:143-52. [PMID: 23002165 DOI: 10.3732/ajb.1200283] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Gravitropism is a process by which plant organs readjust their growth toward or away from the gravity vector when the plant is reoriented. The actin cytoskeleton has often been a significant component of models explaining gravitropism, but its role in this process has become somewhat controversial in light of reports showing that actin inhibitors enhance the gravitropic response. The work with inhibitors implies that actin might function as a negative regulator of gravitropism. In this article, possibilities for how such a role might be accomplished are presented. First, the organization of actin in statocytes is revisited in an attempt to rationalize how compressive forces exerted by statoliths on membranes can lead to enhanced gravity sensing. Second, recent genetic work in the model plant Arabidopsis thaliana is discussed, focusing on the potential involvement of the protein degradation machinery in actin-mediated control of statolith dynamics and on the intriguing possibility that an actin-regulated, ligand-receptor mechanism for gravity signal transduction might operate in higher plants. Third, modifications in the trafficking of auxin efflux transporters are considered as possible mechanisms for the enhanced gravity responses observed in plant organs when the actin cytoskeleton is disrupted by chemical inhibitors. The various possibilities presented in this review emphasize the large amount of research that remains to be done before we can fully understand how the actin cytoskeleton modulates tropisms in higher plants.
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Affiliation(s)
- Elison B Blancaflor
- Plant Biology Division, The Samuel Roberts Noble Foundation Inc., 2510 Sam Noble Parkway, Ardmore, Oklahoma 73401, USA.
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143
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144
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Bargmann BOR, Vanneste S, Krouk G, Nawy T, Efroni I, Shani E, Choe G, Friml J, Bergmann DC, Estelle M, Birnbaum KD. A map of cell type-specific auxin responses. Mol Syst Biol 2013; 9:688. [PMID: 24022006 PMCID: PMC3792342 DOI: 10.1038/msb.2013.40] [Citation(s) in RCA: 115] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Accepted: 07/23/2013] [Indexed: 12/31/2022] Open
Abstract
In plants, changes in local auxin concentrations can trigger a range of developmental processes as distinct tissues respond differently to the same auxin stimulus. However, little is known about how auxin is interpreted by individual cell types. We performed a transcriptomic analysis of responses to auxin within four distinct tissues of the Arabidopsis thaliana root and demonstrate that different cell types show competence for discrete responses. The majority of auxin-responsive genes displayed a spatial bias in their induction or repression. The novel data set was used to examine how auxin influences tissue-specific transcriptional regulation of cell-identity markers. Additionally, the data were used in combination with spatial expression maps of the root to plot a transcriptomic auxin-response gradient across the apical and basal meristem. The readout revealed a strong correlation for thousands of genes between the relative response to auxin and expression along the longitudinal axis of the root. This data set and comparative analysis provide a transcriptome-level spatial breakdown of the response to auxin within an organ where this hormone mediates many aspects of development.
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Affiliation(s)
- Bastiaan O R Bargmann
- Biology Department, Center for Genomics and Systems Biology, New York University, New York, NY, USA
- Department of Cell and Developmental Biology, UCSD, La Jolla, CA, USA
| | - Steffen Vanneste
- Department of Plant Systems Biology, VIB, Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
| | - Gabriel Krouk
- Laboratoire de Biochimie et Physiologie Moléculaire des Plantes, Institut de Biologie Intégrative des Plantes—Claude Grignon, Montpellier, France
| | - Tal Nawy
- Biology Department, Center for Genomics and Systems Biology, New York University, New York, NY, USA
| | - Idan Efroni
- Biology Department, Center for Genomics and Systems Biology, New York University, New York, NY, USA
| | - Eilon Shani
- Department of Cell and Developmental Biology, UCSD, La Jolla, CA, USA
| | - Goh Choe
- Department of Cell and Developmental Biology, UCSD, La Jolla, CA, USA
| | - Jiří Friml
- Department of Plant Systems Biology, VIB, Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
- Institute of Science and Technology Austria (IST Austria), Klosterneuburg, Austria
| | | | - Mark Estelle
- Department of Cell and Developmental Biology, UCSD, La Jolla, CA, USA
| | - Kenneth D Birnbaum
- Biology Department, Center for Genomics and Systems Biology, New York University, New York, NY, USA
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145
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Liu J, Mehdi S, Topping J, Friml J, Lindsey K. Interaction of PLS and PIN and hormonal crosstalk in Arabidopsis root development. FRONTIERS IN PLANT SCIENCE 2013; 4:75. [PMID: 23577016 PMCID: PMC3617403 DOI: 10.3389/fpls.2013.00075] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Accepted: 03/17/2013] [Indexed: 05/05/2023]
Abstract
Understanding how hormones and genes interact to coordinate plant growth is a major challenge in developmental biology. The activities of auxin, ethylene, and cytokinin depend on cellular context and exhibit either synergistic or antagonistic interactions. Here we use experimentation and network construction to elucidate the role of the interaction of the POLARIS peptide (PLS) and the auxin efflux carrier PIN proteins in the crosstalk of three hormones (auxin, ethylene, and cytokinin) in Arabidopsis root development. In ethylene hypersignaling mutants such as polaris (pls), we show experimentally that expression of both PIN1 and PIN2 significantly increases. This relationship is analyzed in the context of the crosstalk between auxin, ethylene, and cytokinin: in pls, endogenous auxin, ethylene and cytokinin concentration decreases, approximately remains unchanged and increases, respectively. Experimental data are integrated into a hormonal crosstalk network through combination with information in literature. Network construction reveals that the regulation of both PIN1 and PIN2 is predominantly via ethylene signaling. In addition, it is deduced that the relationship between cytokinin and PIN1 and PIN2 levels implies a regulatory role of cytokinin in addition to its regulation to auxin, ethylene, and PLS levels. We discuss how the network of hormones and genes coordinates plant growth by simultaneously regulating the activities of auxin, ethylene, and cytokinin signaling pathways.
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Affiliation(s)
- Junli Liu
- The Integrative Cell Biology Laboratory and The Biophysical Sciences Institute, School of Biological and Biomedical Sciences, Durham University, Durham, UK
- *Correspondence: Junli Liu and Keith Lindsey, The Integrative Cell Biology Laboratory and The Biophysical Sciences Institute, School of Biological and Biomedical Sciences, Durham University, South Road, Durham DH1 3LE, UK. e-mail: ;
| | - Saher Mehdi
- The Integrative Cell Biology Laboratory and The Biophysical Sciences Institute, School of Biological and Biomedical Sciences, Durham University, Durham, UK
| | - Jennifer Topping
- The Integrative Cell Biology Laboratory and The Biophysical Sciences Institute, School of Biological and Biomedical Sciences, Durham University, Durham, UK
| | - Jirí Friml
- VIB Department of Plant Systems Biology and Department Plant Biotechnology and Bioinformatics, University of Gent, Gent, Belgium
| | - Keith Lindsey
- The Integrative Cell Biology Laboratory and The Biophysical Sciences Institute, School of Biological and Biomedical Sciences, Durham University, Durham, UK
- *Correspondence: Junli Liu and Keith Lindsey, The Integrative Cell Biology Laboratory and The Biophysical Sciences Institute, School of Biological and Biomedical Sciences, Durham University, South Road, Durham DH1 3LE, UK. e-mail: ;
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146
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SCF(TIR1/AFB)-auxin signalling regulates PIN vacuolar trafficking and auxin fluxes during root gravitropism. EMBO J 2012; 32:260-74. [PMID: 23211744 PMCID: PMC3553380 DOI: 10.1038/emboj.2012.310] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Accepted: 10/19/2012] [Indexed: 01/31/2023] Open
Abstract
The distribution of the phytohormone auxin regulates many aspects of plant development including growth response to gravity. Gravitropic root curvature involves coordinated and asymmetric cell elongation between the lower and upper side of the root, mediated by differential cellular auxin levels. The asymmetry in the auxin distribution is established and maintained by a spatio-temporal regulation of the PIN-FORMED (PIN) auxin transporter activity. We provide novel insights into the complex regulation of PIN abundance and activity during root gravitropism. We show that PIN2 turnover is differentially regulated on the upper and lower side of gravistimulated roots by distinct but partially overlapping auxin feedback mechanisms. In addition to regulating transcription and clathrin-mediated internalization, auxin also controls PIN abundance at the plasma membrane by promoting their vacuolar targeting and degradation. This effect of elevated auxin levels requires the activity of SKP-Cullin-F-box(TIR1/AFB) (SCF(TIR1/AFB))-dependent pathway. Importantly, also suboptimal auxin levels mediate PIN degradation utilizing the same signalling pathway. These feedback mechanisms are functionally important during gravitropic response and ensure fine-tuning of auxin fluxes for maintaining as well as terminating asymmetric growth.
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147
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Brassinosteroids regulate organ boundary formation in the shoot apical meristem of Arabidopsis. Proc Natl Acad Sci U S A 2012; 109:21152-7. [PMID: 23213257 DOI: 10.1073/pnas.1210799110] [Citation(s) in RCA: 124] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Spatiotemporal control of the formation of organ primordia and organ boundaries from the stem cell niche in the shoot apical meristem (SAM) determines the patterning and architecture of plants, but the underlying signaling mechanisms remain poorly understood. Here we show that brassinosteroids (BRs) play a key role in organ boundary formation by repressing organ boundary identity genes. BR-hypersensitive mutants display organ-fusion phenotypes, whereas BR-insensitive mutants show enhanced organ boundaries. The BR-activated transcription factor BZR1 directly represses the cup-shaped cotyledon (CUC) family of organ boundary identity genes. In WT plants, BZR1 accumulates at high levels in the nuclei of central meristem and organ primordia but at a low level in organ boundary cells to allow CUC gene expression. Activation of BR signaling represses CUC gene expression and causes organ fusion phenotypes. This study uncovers a role for BR in the spatiotemporal control of organ boundary formation and morphogenesis in the SAM.
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148
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Lau OS, Bergmann DC. Stomatal development: a plant's perspective on cell polarity, cell fate transitions and intercellular communication. Development 2012; 139:3683-92. [PMID: 22991435 DOI: 10.1242/dev.080523] [Citation(s) in RCA: 145] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The plant stomatal lineage manifests features common to many developmental contexts: precursor cells are chosen from an initially equivalent field of cells, undergo asymmetric and self-renewing divisions, communicate among themselves and respond to information from a distance. As we review here, the experimental accessibility of these epidermal lineages, particularly in Arabidopsis, has made stomata a conceptual and technical framework for the study of cell fate, stem cells, and cell polarity in plants.
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Affiliation(s)
- On Sun Lau
- Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305-5020, USA
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149
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Wang B, Henrichs S, Geisler M. The AGC kinase, PINOID, blocks interactive ABCB/PIN auxin transport. PLANT SIGNALING & BEHAVIOR 2012; 7:1515-7. [PMID: 23073023 PMCID: PMC3578881 DOI: 10.4161/psb.22093] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Plant growth and development is determined by intracellular and intercellular auxin gradients that are controlled at first hand by auxin efflux catalysts of the ABCB/PGP and PIN families. ABCB transport activity was shown to be counter-actively regulated by protein phosphorylation by the AGC protein kinase, PINOID (PID), that is coordinated by interaction with the immunophilin-like FKBP42, TWISTED DWARF1 (TWD1). In contrast, PID was shown to determine PIN polarity, however, the direct impact of PID on PIN activity has yet not been tested. Co-expression in yeast indicates that PID had no effect on PIN1,2 alone but specifically inhibits interactive ABCB1-PIN1/PIN2 auxin efflux in an action that is dependent on its kinase activity. PIN1-PID co-transfection in N. benthamiana revealed that PID blocks PIN1-mediated auxin efflux without changing PIN1 location. In summary, these data provide evidence that PID phosphorylation does not only determine PIN polarity but also has a direct impact on transport activity of the activity of the binary PIN-ABCB1 complex.
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Affiliation(s)
- Bangjun Wang
- Department of Biology-Plant Biology, University of Fribourg, Fribourg, Switzerland
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150
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Lilley JLS, Gee CW, Sairanen I, Ljung K, Nemhauser JL. An endogenous carbon-sensing pathway triggers increased auxin flux and hypocotyl elongation. PLANT PHYSIOLOGY 2012; 160:2261-70. [PMID: 23073695 PMCID: PMC3510146 DOI: 10.1104/pp.112.205575] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Accepted: 10/10/2012] [Indexed: 05/18/2023]
Abstract
The local environment has a substantial impact on early seedling development. Applying excess carbon in the form of sucrose is known to alter both the timing and duration of seedling growth. Here, we show that sucrose changes growth patterns by increasing auxin levels and rootward auxin transport in Arabidopsis (Arabidopsis thaliana). Sucrose likely interacts with an endogenous carbon-sensing pathway via the PHYTOCHROME-INTERACTING FACTOR (PIF) family of transcription factors, as plants grown in elevated carbon dioxide showed the same PIF-dependent growth promotion. Overexpression of PIF5 was sufficient to suppress photosynthetic rate, enhance response to elevated carbon dioxide, and prolong seedling survival in nitrogen-limiting conditions. Thus, PIF transcription factors integrate growth with metabolic demands and thereby facilitate functional equilibrium during photomorphogenesis.
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Affiliation(s)
| | | | - Ilkka Sairanen
- Department of Biology, University of Washington, Seattle, Washington 98195 (J.L.S.L., C.W.G., J.L.N.); Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences, SE–901 83 Umea, Sweden (I.S., K.L.)
| | - Karin Ljung
- Department of Biology, University of Washington, Seattle, Washington 98195 (J.L.S.L., C.W.G., J.L.N.); Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences, SE–901 83 Umea, Sweden (I.S., K.L.)
| | - Jennifer L. Nemhauser
- Department of Biology, University of Washington, Seattle, Washington 98195 (J.L.S.L., C.W.G., J.L.N.); Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences, SE–901 83 Umea, Sweden (I.S., K.L.)
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