401
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Barbosa ICR, Zourelidou M, Willige BC, Weller B, Schwechheimer C. D6 PROTEIN KINASE activates auxin transport-dependent growth and PIN-FORMED phosphorylation at the plasma membrane. Dev Cell 2014; 29:674-85. [PMID: 24930721 DOI: 10.1016/j.devcel.2014.05.006] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Revised: 03/20/2014] [Accepted: 05/09/2014] [Indexed: 12/19/2022]
Abstract
The directed cell-to-cell transport of the phytohormone auxin by efflux and influx transporters is essential for proper plant growth and development. Like auxin efflux facilitators of the PIN-FORMED (PIN) family, D6 PROTEIN KINASE (D6PK) from Arabidopsis thaliana localizes to the basal plasma membrane of many cells, and evidence exists that D6PK may directly phosphorylate PINs. We find that D6PK is a membrane-bound protein that is associated with either the basal domain of the plasma membrane or endomembranes. Inhibition of the trafficking regulator GNOM leads to a rapid internalization of D6PK to endomembranes. Interestingly, the dissociation of D6PK from the plasma membrane is also promoted by auxin. Surprisingly, we find that auxin transport-dependent tropic responses are critically and reversibly controlled by D6PK and D6PK-dependent PIN phosphorylation at the plasma membrane. We conclude that D6PK abundance at the plasma membrane and likely D6PK-dependent PIN phosphorylation are prerequisites for PIN-mediated auxin transport.
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Affiliation(s)
- Inês C R Barbosa
- Department of Plant Systems Biology, Center of Life and Food Sciences Weihenstephan, Technische Universität München, 85354 Freising, Germany
| | - Melina Zourelidou
- Department of Plant Systems Biology, Center of Life and Food Sciences Weihenstephan, Technische Universität München, 85354 Freising, Germany
| | - Björn C Willige
- Department of Plant Systems Biology, Center of Life and Food Sciences Weihenstephan, Technische Universität München, 85354 Freising, Germany
| | - Benjamin Weller
- Department of Plant Systems Biology, Center of Life and Food Sciences Weihenstephan, Technische Universität München, 85354 Freising, Germany
| | - Claus Schwechheimer
- Department of Plant Systems Biology, Center of Life and Food Sciences Weihenstephan, Technische Universität München, 85354 Freising, Germany.
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402
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Plant roots use a patterning mechanism to position lateral root branches toward available water. Proc Natl Acad Sci U S A 2014; 111:9319-24. [PMID: 24927545 DOI: 10.1073/pnas.1400966111] [Citation(s) in RCA: 213] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The architecture of the branched root system of plants is a major determinant of vigor. Water availability is known to impact root physiology and growth; however, the spatial scale at which this stimulus influences root architecture is poorly understood. Here we reveal that differences in the availability of water across the circumferential axis of the root create spatial cues that determine the position of lateral root branches. We show that roots of several plant species can distinguish between a wet surface and air environments and that this also impacts the patterning of root hairs, anthocyanins, and aerenchyma in a phenomenon we describe as hydropatterning. This environmental response is distinct from a touch response and requires available water to induce lateral roots along a contacted surface. X-ray microscale computed tomography and 3D reconstruction of soil-grown root systems demonstrate that such responses also occur under physiologically relevant conditions. Using early-stage lateral root markers, we show that hydropatterning acts before the initiation stage and likely determines the circumferential position at which lateral root founder cells are specified. Hydropatterning is independent of endogenous abscisic acid signaling, distinguishing it from a classic water-stress response. Higher water availability induces the biosynthesis and transport of the lateral root-inductive signal auxin through local regulation of tryptophan aminotransferase of Arabidopsis 1 and PIN-formed 3, both of which are necessary for normal hydropatterning. Our work suggests that water availability is sensed and interpreted at the suborgan level and locally patterns a wide variety of developmental processes in the root.
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403
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Abstract
The astonishingly long lives of plants and their regeneration capacity depend on the activity of plant stem cells. As in animals, stem cells reside in stem cell niches, which produce signals that regulate the balance between self-renewal and the generation of daughter cells that differentiate into new tissues. Plant stem cell niches are located within the meristems, which are organized structures that are responsible for most post-embryonic development. The continuous organ production that is characteristic of plant growth requires a robust regulatory network to keep the balance between pluripotent stem cells and differentiating progeny. Components of this network have now been elucidated and provide a unique opportunity for comparing strategies that were developed in the animal and plant kingdoms, which underlie the logic of stem cell behaviour.
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404
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Yuan TT, Xu HH, Zhang KX, Guo TT, Lu YT. Glucose inhibits root meristem growth via ABA INSENSITIVE 5, which represses PIN1 accumulation and auxin activity in Arabidopsis. PLANT, CELL & ENVIRONMENT 2014; 37:1338-50. [PMID: 24237322 DOI: 10.1111/pce.12233] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Accepted: 11/05/2013] [Indexed: 05/18/2023]
Abstract
Glucose functions as a hormone-like signalling molecule that modulates plant growth and development in Arabidopsis thaliana. However, the role of glucose in root elongation remains elusive. Our study demonstrates that high concentrations of glucose reduce the size of the root meristem zone by repressing PIN1 accumulation and thereby reducing auxin levels. In addition, we verified the involvement of ABA INSENSITIVE 5 (ABI5) in this process by showing that abi5-1 is less sensitive to glucose than the wild type, whereas glucose induces ABI5 expression and the inducible overexpression of ABI5 reduces the size of the root meristem zone. Furthermore, the inducible overexpression of ABI5 in PIN1::PIN1-GFP plants reduces the level of PIN1-GFP, but glucose reduces the level of PIN1-GFP to a lesser extent in abi5-1 PIN1::PIN1-GFP plants than in the PIN1::PIN1-GFP control, suggesting that ABI5 is involved in glucose-regulated PIN1 accumulation. Taken together, our data suggest that ABI5 functions in the glucose-mediated inhibition of the root meristem zone by repressing PIN1 accumulation, thus leading to reduced auxin levels in roots.
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Affiliation(s)
- Ting-Ting Yuan
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, 430072, China
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405
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Chen Q, Dai X, De-Paoli H, Cheng Y, Takebayashi Y, Kasahara H, Kamiya Y, Zhao Y. Auxin overproduction in shoots cannot rescue auxin deficiencies in Arabidopsis roots. PLANT & CELL PHYSIOLOGY 2014; 55:1072-9. [PMID: 24562917 PMCID: PMC4051135 DOI: 10.1093/pcp/pcu039] [Citation(s) in RCA: 153] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Accepted: 02/18/2014] [Indexed: 05/18/2023]
Abstract
Auxin plays an essential role in root development. It has been a long-held dogma that auxin required for root development is mainly transported from shoots into roots by polarly localized auxin transporters. However, it is known that auxin is also synthesized in roots. Here we demonstrate that a group of YUCCA (YUC) genes, which encode the rate-limiting enzymes for auxin biosynthesis, plays an essential role in Arabidopsis root development. Five YUC genes (YUC3, YUC5, YUC7, YUC8 and YUC9) display distinct expression patterns during root development. Simultaneous inactivation of the five YUC genes (yucQ mutants) leads to the development of very short and agravitropic primary roots. The yucQ phenotypes are rescued by either adding 5 nM of the natural auxin, IAA, in the growth media or by expressing a YUC gene in the roots of yucQ. Interestingly, overexpression of a YUC gene in shoots in yucQ causes the characteristic auxin overproduction phenotypes in shoots; however, the root defects of yucQ are not rescued. Our data demonstrate that localized auxin biosynthesis in roots is required for normal root development and that auxin transported from shoots is not sufficient for supporting root elongation and root gravitropic responses.
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Affiliation(s)
- Qingguo Chen
- Section of Cell and Developmental Biology, University of California at San Diego, La Jolla, CA 92093-0116, USA
| | - Xinhua Dai
- Section of Cell and Developmental Biology, University of California at San Diego, La Jolla, CA 92093-0116, USA
| | - Henrique De-Paoli
- Section of Cell and Developmental Biology, University of California at San Diego, La Jolla, CA 92093-0116, USA
| | - Youfa Cheng
- Section of Cell and Developmental Biology, University of California at San Diego, La Jolla, CA 92093-0116, USA
| | - Yumiko Takebayashi
- RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, 230-0045 Japan
| | - Hiroyuki Kasahara
- RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, 230-0045 Japan
| | - Yuji Kamiya
- RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, 230-0045 Japan
| | - Yunde Zhao
- Section of Cell and Developmental Biology, University of California at San Diego, La Jolla, CA 92093-0116, USA
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406
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Takatsuka H, Umeda M. Hormonal control of cell division and elongation along differentiation trajectories in roots. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:2633-43. [PMID: 24474807 DOI: 10.1093/jxb/ert485] [Citation(s) in RCA: 139] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The continuous development of roots is supported by a sustainable system for cell production and growth at the root tip. In the stem cell niche that consists of a quiescent centre and surrounding stem cells, an undifferentiated state and low mitotic activity are preserved by the action of auxin and abscisic acid. Stem cell daughters divide several times in the proximal meristem, where auxin and gibberellin mainly promote cell proliferation. Cells then elongate with the help of gibberellin, and become finally differentiated as a constituent of a cell file in the elongation/differentiation zone. In the model plant Arabidopsis thaliana, the transition zone is located between the proximal meristem and the elongation/differentiation zone, and plays an important role in switching from mitosis to the endoreplication that causes DNA polyploidization. Recent studies have shown that cytokinins are essentially required for this transition by antagonizing auxin signalling and promoting degradation of mitotic regulators. In each root zone, different phytohormones interact with one another and coordinately control cell proliferation, cell elongation, cell differentiation, and endoreplication. Such hormonal networks maintain the elaborate structure of the root tip under various environmental conditions. In this review, we summarize and discuss key issues related to hormonal regulation of root growth, and describe how phytohormones are associated with the control of cell cycle machinery.
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Affiliation(s)
- Hirotomo Takatsuka
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Takayama 8916-5, Ikoma, Nara 630-0192, Japan
| | - Masaaki Umeda
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Takayama 8916-5, Ikoma, Nara 630-0192, Japan JST, CREST, Takayama 8916-5, Ikoma, Nara 630-0192, Japan
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407
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de Lucas M, Prat S. PIFs get BRright: PHYTOCHROME INTERACTING FACTORs as integrators of light and hormonal signals. THE NEW PHYTOLOGIST 2014; 202:1126-1141. [PMID: 24571056 DOI: 10.1111/nph.12725] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2013] [Accepted: 01/08/2014] [Indexed: 05/19/2023]
Abstract
Light and temperature, in coordination with the endogenous clock and the hormones gibberellin (GA) and brassinosteroids (BRs), modulate plant growth and development by affecting the expression of multiple cell wall- and auxin-related genes. PHYTOCHROME INTERACTING FACTORS (PIFs) play a central role in the activation of these genes, the activity of these factors being regulated by the circadian clock and phytochrome-mediated protein destabilization. GA signaling is also integrated at the level of PIFs; the DELLA repressors are found to bind these factors and impair their DNA-binding ability. The recent finding that PIFs are co-activated by BES1 and BZR1 highlights a further role of these regulators in BR signal integration, and reveals that PIFs act in a concerted manner with the BR-related BES1/BZR1 factors to activate auxin synthesis and transport at the gene expression level, and synergistically activate several genes with a role in cell expansion. Auxins feed back into this growth regulatory module by inducing GA biosynthesis and BES1/BZR1 gene expression, in addition to directly regulating several of these growth pathway gene targets. An exciting challenge in the future will be to understand how this growth program is dynamically regulated in time and space to orchestrate differential organ expansion and to provide plants with adaptation flexibility.
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Affiliation(s)
- Miguel de Lucas
- Departamento Genética Molecular de Plantas, Centro Nacional de Biotecnología- CSIC, Darwin 3, 28049, Madrid, Spain
| | - Salomé Prat
- Departamento Genética Molecular de Plantas, Centro Nacional de Biotecnología- CSIC, Darwin 3, 28049, Madrid, Spain
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408
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Roy R, Bassham DC. Root growth movements: waving and skewing. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2014; 221-222:42-7. [PMID: 24656334 DOI: 10.1016/j.plantsci.2014.01.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Revised: 01/11/2014] [Accepted: 01/22/2014] [Indexed: 05/20/2023]
Abstract
Roots anchor a plant in the soil, acquire nutrition and respond to environmental cues. Roots perform these functions using intricate movements and a variety of pathways have been implicated in mediating their growth patterns. These include endogenous genetic factors, perception of multiple environmental stimuli, signaling pathways interacting with hormonal dynamics and cellular processes of rapid cell elongation. In this review we attempt to consolidate our understanding of two specific types of root movements, waving and skewing, that arise on the surface of growth media, and how they are regulated by various genes and factors. These include crucial factors that are part of a complex nexus of processes including polar auxin transport and cytoskeletal dynamics. This knowledge can be extrapolated in the future for engineering plants with root architecture better suited for different soil and growth conditions such as abiotic stresses or even extended spaceflight. Technological innovations and interdisciplinary approaches promise to allow the tracking of root movements on a much finer scale, thus helping to expedite the discovery of more nodes in the regulation of root waving and skewing and movement in general.
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Affiliation(s)
- Rahul Roy
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA.
| | - Diane C Bassham
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA; Plant Sciences Institute, Iowa State University, Ames, IA 50011, USA.
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409
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Pattison RJ, Csukasi F, Catalá C. Mechanisms regulating auxin action during fruit development. PHYSIOLOGIA PLANTARUM 2014; 151:62-72. [PMID: 24329770 DOI: 10.1111/ppl.12142] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Revised: 12/06/2013] [Accepted: 12/11/2013] [Indexed: 05/22/2023]
Abstract
Auxin controls many aspects of fruit development, including fruit set and growth, ripening and abscission. However, the mechanisms by which auxin regulates these processes are still poorly understood. While it is generally agreed that precise spatial and temporal control of auxin distribution and signaling are required for fruit development, the dynamics of auxin biosynthesis and the mechanisms for its transport to different fruit tissues are mostly unknown. Despite major advances in elucidating many aspects of auxin biology in vegetative tissues, until recently, the nature and importance of auxin metabolism, transport and signaling during fruit ontogeny remained obscure. In this review, we summarize recent research that has started to elucidate the molecular mechanisms by which auxin is produced and transported in the fruit and to unravel the complexity of auxin signaling during fruit development. We also discuss recent approaches used to reveal the genes and regulatory networks that mediate cell and tissue-specific control of auxin levels in the developing fruit.
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410
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Goh T, Voβ U, Farcot E, Bennett MJ, Bishopp A. Systems biology approaches to understand the role of auxin in root growth and development. PHYSIOLOGIA PLANTARUM 2014; 151:73-82. [PMID: 24494934 DOI: 10.1111/ppl.12162] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Revised: 01/28/2014] [Accepted: 01/30/2014] [Indexed: 05/08/2023]
Abstract
The past decade has seen major advances in our understanding of auxin regulated root growth and developmental processes. Key genes have been identified that regulate and/or mediate auxin homeostasis, transport, perception and response. The molecular and biochemical reactions that underpin auxin signalling are non-linear, with feed-forward and feedback loops contributing to the robustness of the system. As our knowledge of auxin biology becomes increasingly complex and their outputs less intuitive, modelling is set to become much more important. For the last several decades modelling efforts have focused on auxin transport and, latterly, on auxin response. Recently researchers have employed multi-scale modelling approaches to predict emergent properties at the tissue and organ scales. Such innovative modelling approaches are proving very promising, revealing new mechanistic insights about how auxin functions within a multicellular context to control plant growth and development. In this review we initially describe examples of models capturing auxin transport and response pathways, and then discuss increasingly complex models that integrate multiple hormone response pathways, tissues and/or scales.
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Affiliation(s)
- Tatsuaki Goh
- Centre for Plant Integrative Biology, School of Biosciences, University of Nottingham, Loughborough, UK; Graduate School of Science, Kobe University, Kobe, Hyogo, Japan
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411
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Ursache R, Miyashima S, Chen Q, Vatén A, Nakajima K, Carlsbecker A, Zhao Y, Helariutta Y, Dettmer J. Tryptophan-dependent auxin biosynthesis is required for HD-ZIP III-mediated xylem patterning. Development 2014; 141:1250-9. [PMID: 24595288 DOI: 10.1242/dev.103473] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The development and growth of higher plants is highly dependent on the conduction of water and minerals throughout the plant by xylem vessels. In Arabidopsis roots the xylem is organized as an axis of cell files with two distinct cell fates: the central metaxylem and the peripheral protoxylem. During vascular development, high and low expression levels of the class III HD-ZIP transcription factors promote metaxylem and protoxylem identities, respectively. Protoxylem specification is determined by both mobile, ground tissue-emanating miRNA165/6 species, which downregulate, and auxin concentrated by polar transport, which promotes HD-ZIP III expression. However, the factors promoting high HD-ZIP III expression for metaxylem identity have remained elusive. We show here that auxin biosynthesis promotes HD-ZIP III expression and metaxylem specification. Several auxin biosynthesis genes are expressed in the outer layers surrounding the vascular tissue in Arabidopsis root and downregulation of HD-ZIP III expression accompanied by specific defects in metaxylem development is seen in auxin biosynthesis mutants, such as trp2-12, wei8 tar2 or a quintuple yucca mutant, and in plants treated with L-kynurenine, a pharmacological inhibitor of auxin biosynthesis. Some of the patterning defects can be suppressed by synthetically elevated HD-ZIP III expression. Taken together, our results indicate that polar auxin transport, which was earlier shown to be required for protoxylem formation, is not sufficient to establish a proper xylem axis but that root-based auxin biosynthesis is additionally required.
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Affiliation(s)
- Robertas Ursache
- Institute of Biotechnology, Department of Bio and Environmental Sciences, University of Helsinki, FIN-00014, Finland
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412
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Tian H, Jia Y, Niu T, Yu Q, Ding Z. The key players of the primary root growth and development also function in lateral roots in Arabidopsis. PLANT CELL REPORTS 2014; 33:745-53. [PMID: 24504658 DOI: 10.1007/s00299-014-1575-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Revised: 12/25/2013] [Accepted: 01/20/2014] [Indexed: 05/04/2023]
Abstract
The core regulators which are required for primary root growth and development also function in lateral root development or lateral root stem cell niche maintenance. The primary root systems and the lateral root systems are the two important root systems which are vital to the survival of plants. Though the molecular mechanism of the growth and development of both the primary root systems and the lateral root systems have been extensively studied individually in Arabidopsis, there are not so much evidence to show that if both root systems share common regulatory mechanisms. AP2 family transcription factors such as PLT1 (PLETHORA1) and PLT2, GRAS family transcription factors such as SCR (SCARECROW) and SHR (SHORT ROOT) and WUSCHEL-RELATED HOMEOBOX transcription factor WOX5 have been extensively studied and found to be essential for primary root growth and development. In this study, through the expression pattern analysis and mutant examinations, we found that these core regulators also function in lateral root development or lateral root stem cell niche maintenance.
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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, Jinan, People's Republic of China
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413
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Ma Q, Robert S. Auxin biology revealed by small molecules. PHYSIOLOGIA PLANTARUM 2014; 151:25-42. [PMID: 24252105 DOI: 10.1111/ppl.12128] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Revised: 11/07/2013] [Accepted: 11/08/2013] [Indexed: 05/08/2023]
Abstract
The plant hormone auxin regulates virtually every aspect of plant growth and development and unraveling its molecular and cellular modes of action is fundamental for plant biology research. Chemical genomics is the use of small molecules to modify protein functions. This approach currently rises as a powerful technology for basic research. Small compounds with auxin-like activities or affecting auxin-mediated biological processes have been widely used in auxin research. They can serve as a tool complementary to genetic and genomic methods, facilitating the identification of an array of components modulating auxin metabolism, transport and signaling. The employment of high-throughput screening technologies combined with informatics-based chemical design and organic chemical synthesis has since yielded many novel small molecules with more instantaneous, precise and specific functionalities. By applying those small molecules, novel molecular targets can be isolated to further understand and dissect auxin-related pathways and networks that otherwise are too complex to be elucidated only by gene-based methods. Here, we will review examples of recently characterized molecules used in auxin research, highlight the strategies of unraveling the mechanisms of these small molecules and discuss future perspectives of small molecule applications in auxin biology.
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Affiliation(s)
- Qian Ma
- Umeå Plant Science Center, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-901 83, Umeå, Sweden
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414
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Peer WA, Jenness MK, Murphy AS. Measure for measure: determining, inferring and guessing auxin gradients at the root tip. PHYSIOLOGIA PLANTARUM 2014; 151:97-111. [PMID: 24617531 DOI: 10.1111/ppl.12182] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 03/05/2014] [Accepted: 03/07/2014] [Indexed: 05/03/2023]
Abstract
The plant hormone auxin is transported from sites of synthesis to sites of action. Auxin responses are mediated by fast (non-transcriptional) and slow (transcriptional; ubiquitinylation) responses, which affect physiological changes at cellular and organismal scales. As such, auxin transport vectors regulate programmed and plastic growth responses to optimize growth and development. Here we address some common problems in extrapolating 'universal' understanding of auxin transport streams from analyses of loss-of-function mutants and auxin transport inhibitors. We also discuss the analytical methods and tools used to directly quantify, measure and infer auxin gradients within the plant [DR5:GUS/GFP (beta-glucuronidase/green fluorescent protein), DII-VENUS; surface electrodes, direct quantification]. We discuss the assumptions and limitations of each of these analyses, present comparative summaries of auxin transport methods and assay conditions (diffusion, non-specific transport and relevant assay conditions), and consider what is actually being transported and measured [labeled-indole-3-acetic acid (IAA), IAA metabolites].
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Affiliation(s)
- Wendy Ann Peer
- Department of Environmental Science and Technology, University of Maryland, College Park, MD, 20742, USA; Department of Plant Science and Landscape Architecture, University of Maryland, College Park, MD, 20742, USA
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415
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Sozzani R, Busch W, Spalding EP, Benfey PN. Advanced imaging techniques for the study of plant growth and development. TRENDS IN PLANT SCIENCE 2014; 19:304-10. [PMID: 24434036 PMCID: PMC4008707 DOI: 10.1016/j.tplants.2013.12.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 11/29/2013] [Accepted: 12/11/2013] [Indexed: 05/07/2023]
Abstract
A variety of imaging methodologies are being used to collect data for quantitative studies of plant growth and development from living plants. Multi-level data, from macroscopic to molecular, and from weeks to seconds, can be acquired. Furthermore, advances in parallelized and automated image acquisition enable the throughput to capture images from large populations of plants under specific growth conditions. Image-processing capabilities allow for 3D or 4D reconstruction of image data and automated quantification of biological features. These advances facilitate the integration of imaging data with genome-wide molecular data to enable systems-level modeling.
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Affiliation(s)
- Rosangela Sozzani
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA
| | - Wolfgang Busch
- Gregor Mendel Institute of Molecular Plant Biology, Austrian Academy of Sciences, 1030 Vienna, Austria
| | - Edgar P Spalding
- Department of Botany, University of Wisconsin, Madison, WI 53706 USA
| | - Philip N Benfey
- Department of Biology, Duke Center for Systems Biology, and Howard Hughes Medical Institute, Duke University, Durham, NC 27708, USA.
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416
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Abstract
Auxin signaling through the SCF(TIR1)-Aux/IAA-ARF pathway is one of the best-studied plant hormone response pathways. Components of this pathway, from receptors through to transcription factors, have been identified and analyzed in detail. Although we understand elementary aspects of how the auxin signal is perceived and leads to a transcriptional response, many questions remain about the in vivo function of the pathway. Two crucial issues are the tissue specificity of the response, i.e. how distinct cell types can interpret the same auxin signal differently, and the response to a signaling gradient, i.e. how a graded distribution of auxin can elicit distinct expression patterns along its range. Here, we speculate on how signaling through the canonical SCF(TIR1)-Aux/IAA-ARF pathway may achieve divergent responses.
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417
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Waadt R, Hitomi K, Nishimura N, Hitomi C, Adams SR, Getzoff ED, Schroeder JI. FRET-based reporters for the direct visualization of abscisic acid concentration changes and distribution in Arabidopsis. eLife 2014; 3:e01739. [PMID: 24737861 PMCID: PMC3985518 DOI: 10.7554/elife.01739] [Citation(s) in RCA: 170] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Abscisic acid (ABA) is a plant hormone that regulates plant growth and development and mediates abiotic stress responses. Direct cellular monitoring of dynamic ABA concentration changes in response to environmental cues is essential for understanding ABA action. We have developed ABAleons: ABA-specific optogenetic reporters that instantaneously convert the phytohormone-triggered interaction of ABA receptors with PP2C-type phosphatases to send a fluorescence resonance energy transfer (FRET) signal in response to ABA. We report the design, engineering and use of ABAleons with ABA affinities in the range of 100–600 nM to map ABA concentration changes in plant tissues with spatial and temporal resolution. High ABAleon expression can partially repress Arabidopsis ABA responses. ABAleons report ABA concentration differences in distinct cell types, ABA concentration increases in response to low humidity and NaCl in guard cells and to NaCl and osmotic stress in roots and ABA transport from the hypocotyl to the shoot and root. DOI:http://dx.doi.org/10.7554/eLife.01739.001 Plants are able to respond to detrimental changes in their environment—when, for example, water becomes scarce or the soil becomes too salty—in ways that minimize stress and damage caused by these changes. Hormones are chemicals that trigger the plant’s response under these circumstances. Abscisic acid is the hormone that regulates how plants respond to drought and salt stress and that controls the plant growth in these conditions. In the past, it was possible to measure the average level of this hormone in a given tissue, but not the level in individual cells in a living plant. Moreover, it was difficult to follow directly how abscisic acid moved between the plant cells, tissues or organs. Now, Waadt et al. (and independently Jones et al.) have developed tools that can measure the levels of abscisic acid within individual cells in living plants and in real time. The plants were genetically engineered to produce sensor proteins with two properties: they can bind to abscisic acid in a reversible manner, and they contain two ‘tags’ that fluoresce at different wavelengths. Shining light onto the plant at a specific wavelength that is only absorbed by one of the tags actually causes both of the tags on the sensor proteins to fluoresce. However, the sensors fluoresce more at one wavelength when they are bound to abscisic acid, and more at the other wavelength when they are not bound to abscisic acid. Hence, measuring the ratio of these two wavelengths in the light that is given off by the sensor proteins can be used as a measure of the concentration of abscisic acid in a plant cell. Waadt et al. developed sensor proteins called ‘ABAleons’, and used one of these to analyze the uptake, distribution and movement of abscisic acid in different tissues in the model plant Arabidopsis thaliana. Changes in the level of abscisic acid could be detected at the level of an individual plant cell, and over time scales of fractions of seconds to hours. ABAleons also revealed that the concentration of abscisic acid in guard cells—specialized cells that help stop the loss of water vapor from a leaf—increases when humidity levels are low, or when salt levels are high. Low water levels, or high salt levels, also slowly increased the concentration of abscisic acid in the roots of the plant. Furthermore, Waadt et al. saw that abscisic acid moved long distances from the base of the stem up into the shoot, and down to the root. Waadt et al. also report that the ABAleons made plants less responsive to abscisic acid, possibly because binding to the ABAleons reduced the amount of abscisic acid that was available to perform its role as a hormone. The next challenge is to engineer ABAleons that minimize this unwanted side effect, and then go on to use ABAleons to study environmental conditions and proteins involved in plant hormone responses. DOI:http://dx.doi.org/10.7554/eLife.01739.002
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Affiliation(s)
- Rainer Waadt
- Division of Biological Sciences, Cell and Developmental Biology Section, University of California, San Diego, La Jolla, United States
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418
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Auxin-callose-mediated plasmodesmal gating is essential for tropic auxin gradient formation and signaling. Dev Cell 2014; 28:132-46. [PMID: 24480642 DOI: 10.1016/j.devcel.2013.12.008] [Citation(s) in RCA: 127] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 10/16/2013] [Accepted: 12/10/2013] [Indexed: 01/10/2023]
Abstract
In plants, auxin functions as a master controller of development, pattern formation, morphogenesis, and tropic responses. A sophisticated transport system has evolved to allow the establishment of precise spatiotemporal auxin gradients that regulate specific developmental programs. A critical unresolved question relates to how these gradients can be maintained in the presence of open plasmodesmata that allow for symplasmic exchange of essential nutrients and signaling macromolecules. Here we addressed this conundrum using genetic, physiological, and cell biological approaches and identified the operation of an auxin-GSL8 feedback circuit that regulates the level of plasmodesmal-localized callose in order to locally downregulate symplasmic permeability during hypocotyl tropic response. This system likely involves a plasmodesmal switch that would prevent the dissipation of a forming gradient by auxin diffusion through the symplasm. This regulatory system may represent a mechanism by which auxin could also regulate symplasmic delivery of a wide range of signaling agents.
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419
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A highly selective biosensor with nanomolar sensitivity based on cytokinin dehydrogenase. PLoS One 2014; 9:e90877. [PMID: 24595403 PMCID: PMC3942484 DOI: 10.1371/journal.pone.0090877] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Accepted: 02/03/2014] [Indexed: 11/19/2022] Open
Abstract
We have developed a N6-dimethylallyladenine (cytokinin) dehydrogenase-based microbiosensor for real-time determination of the family of hormones known as cytokinins. Cytokinin dehydrogenase from Zea mays (ZmCKX1) was immobilised concurrently with electrodeposition of a silica gel film on the surface of a Pt microelectrode, which was further functionalized by free electron mediator 2,6-dichlorophenolindophenol (DCPIP) in supporting electrolyte to give a bioactive film capable of selective oxidative cleavage of the N6- side chain of cytokinins. The rapid electron shuffling between freely diffusible DCPIP and the FAD redox group in ZmCKX1 endowed the microbiosensor with a fast response time of less than 10 s. The immobilised ZmCKX1 retained a high affinity for its preferred substrate N6-(Δ2-isopentenyl) adenine (iP), and gave the miniaturized biosensor a large linear dynamic range from 10 nM to 10 µM, a detection limit of 3.9 nM and a high sensitivity to iP of 603.3 µAmM-1cm-2 (n = 4, R2 = 0.9999). Excellent selectivity was displayed for several other aliphatic cytokinins and their ribosides, including N6-(Δ2-isopentenyl) adenine, N6-(Δ2-isopentenyl) adenosine, cis-zeatin, trans-zeatin and trans-zeatin riboside. Aromatic cytokinins and metabolites such as cytokinin glucosides were generally poor substrates. The microbiosensors exhibited excellent stability in terms of pH and long-term storage and have been used successfully to determine low nanomolar cytokinin concentrations in tomato xylem sap exudates.
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420
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Horstman A, Willemsen V, Boutilier K, Heidstra R. AINTEGUMENTA-LIKE proteins: hubs in a plethora of networks. TRENDS IN PLANT SCIENCE 2014; 19:146-57. [PMID: 24280109 DOI: 10.1016/j.tplants.2013.10.010] [Citation(s) in RCA: 106] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 10/24/2013] [Accepted: 10/27/2013] [Indexed: 05/18/2023]
Abstract
Members of the AINTEGUMENTA-LIKE (AIL) family of APETALA 2/ETHYLENE RESPONSE FACTOR (AP2/ERF) domain transcription factors are expressed in all dividing tissues in the plant, where they have central roles in developmental processes such as embryogenesis, stem cell niche specification, meristem maintenance, organ positioning, and growth. When overexpressed, AIL proteins induce adventitious growth, including somatic embryogenesis and ectopic organ formation. The Arabidopsis (Arabidopsis thaliana) genome contains eight AIL genes, including AINTEGUMENTA, BABY BOOM, and the PLETHORA genes. Studies on these transcription factors have revealed their intricate relationship with auxin as well as their involvement in an increasing number of gene regulatory networks, in which extensive crosstalk and feedback loops have a major role.
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Affiliation(s)
- Anneke Horstman
- Plant Research International, Wageningen University and Research Centre, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Viola Willemsen
- Plant Developmental Biology, Wageningen University and Research Centre, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Kim Boutilier
- Plant Research International, Wageningen University and Research Centre, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Renze Heidstra
- Plant Developmental Biology, Wageningen University and Research Centre, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands.
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421
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Band LR, Wells DM, Fozard JA, Ghetiu T, French AP, Pound MP, Wilson MH, Yu L, Li W, Hijazi HI, Oh J, Pearce SP, Perez-Amador MA, Yun J, Kramer E, Alonso JM, Godin C, Vernoux T, Hodgman TC, Pridmore TP, Swarup R, King JR, Bennett MJ. Systems analysis of auxin transport in the Arabidopsis root apex. THE PLANT CELL 2014; 26:862-75. [PMID: 24632533 PMCID: PMC4001398 DOI: 10.1105/tpc.113.119495] [Citation(s) in RCA: 148] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Revised: 01/06/2014] [Accepted: 02/14/2014] [Indexed: 05/17/2023]
Abstract
Auxin is a key regulator of plant growth and development. Within the root tip, auxin distribution plays a crucial role specifying developmental zones and coordinating tropic responses. Determining how the organ-scale auxin pattern is regulated at the cellular scale is essential to understanding how these processes are controlled. In this study, we developed an auxin transport model based on actual root cell geometries and carrier subcellular localizations. We tested model predictions using the DII-VENUS auxin sensor in conjunction with state-of-the-art segmentation tools. Our study revealed that auxin efflux carriers alone cannot create the pattern of auxin distribution at the root tip and that AUX1/LAX influx carriers are also required. We observed that AUX1 in lateral root cap (LRC) and elongating epidermal cells greatly enhance auxin's shootward flux, with this flux being predominantly through the LRC, entering the epidermal cells only as they enter the elongation zone. We conclude that the nonpolar AUX1/LAX influx carriers control which tissues have high auxin levels, whereas the polar PIN carriers control the direction of auxin transport within these tissues.
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Affiliation(s)
- Leah R. Band
- Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
| | - Darren M. Wells
- Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
| | - John A. Fozard
- Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
| | - Teodor Ghetiu
- Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
| | - Andrew P. French
- Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
| | - Michael P. Pound
- Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
| | - Michael H. Wilson
- Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
| | - Lei Yu
- Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
| | - Wenda Li
- Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
| | - Hussein I. Hijazi
- Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
| | - Jaesung Oh
- Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
| | - Simon P. Pearce
- Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
| | - Miguel A. Perez-Amador
- Instituto de Biología Molecular y Celular de Plantas, Universidad Politécnica de Valencia–Consejo Superior de Investigaciones Científicas, Ciudad Politécnica de la Innovación, 46022 Valencia, Spain
| | - Jeonga Yun
- Department of Genetics, North Carolina State University, Raleigh, North Carolina 27695
| | - Eric Kramer
- Physics Department, Bard College at Simon’s Rock, Great Barrington, Massachusetts 01230
| | - Jose M. Alonso
- Department of Genetics, North Carolina State University, Raleigh, North Carolina 27695
| | - Christophe Godin
- Virtual Plants Project Team, Unité Mixte de Recherche, Amélioration Génétique des Plantes Méditerranéennes et Tropicales, Institut National de Recherche en Informatique et en Automatique/Centre de Coopération Internationale en Recherche Agronomique pour le Développement, 34095 Montpellier, France
| | - Teva Vernoux
- Laboratoire de Reproduction et Developpement des Plantes, CNRS, INRA, Ecole Normale Supérieure Lyon, Université Claude Bernard Lyon 1, Université de Lyon, 69364 Lyon, France
| | - T. Charlie Hodgman
- Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
| | - Tony P. Pridmore
- Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
| | - Ranjan Swarup
- Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
| | - John R. King
- Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
| | - Malcolm J. Bennett
- Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
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422
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Hamers D, van Voorst Vader L, Borst JW, Goedhart J. Development of FRET biosensors for mammalian and plant systems. PROTOPLASMA 2014; 251:333-347. [PMID: 24337770 DOI: 10.1007/s00709-013-0590-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Accepted: 11/19/2013] [Indexed: 06/03/2023]
Abstract
Genetically encoded biosensors are increasingly used in visualising signalling processes in different organisms. Sensors based on green fluorescent protein technology are providing a great opportunity for using Förster resonance energy transfer (FRET) as a tool that allows for monitoring dynamic processes in living cells. The development of these FRET biosensors requires careful selection of fluorophores, substrates and recognition domains. In this review, we will discuss recent developments, strategies to create and optimise FRET biosensors and applications of FRET-based biosensors for use in the two major eukaryotic kingdoms and elaborate on different methods for FRET detection.
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Affiliation(s)
- Danny Hamers
- Laboratory of Biochemistry and Microspectroscopy Centre, Wageningen University, Wageningen, The Netherlands
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423
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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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424
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Kofuji R, Hasebe M. Eight types of stem cells in the life cycle of the moss Physcomitrella patens. CURRENT OPINION IN PLANT BIOLOGY 2014; 17:13-21. [PMID: 24507489 DOI: 10.1016/j.pbi.2013.10.007] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Revised: 10/13/2013] [Accepted: 10/14/2013] [Indexed: 05/18/2023]
Abstract
Stem cells self-renew and produce cells that differentiate to become the source of the plant body. The moss Physcomitrella patens forms eight types of stem cells during its life cycle and serves as a useful model in which to explore the evolution of such cells. The common ancestor of land plants is inferred to have been haplontic and to have formed stem cells only in the gametophyte generation. A single stem cell would have been maintained in the ancestral gametophyte meristem, as occurs in extant basal land plants. During land plant evolution, stem cells diverged in the gametophyte generation to form different types of body parts, including the protonema and rhizoid filaments, leafy-shoot and thalloid gametophores, and gametangia formed in moss. A simplex meristem with a single stem cell was acquired in the sporophyte generation early in land plant evolution. Subsequently, sporophyte stem cells became multiple in the meristem and were elaborated further in seed plant lineages, although the evolutionary origin of niche cells, which maintain stem cells is unknown. Comparisons of gene regulatory networks are expected to give insights into the general mechanisms of stem cell formation and maintenance in land plants and provide information about their evolution. P. patens develops at least seven types of simplex meristem in the gametophyte and at least one type in the sporophyte generation and is a good material for regulatory network comparisons. In this review, we summarize recently revealed molecular mechanisms of stem cell initiation and maintenance in the moss.
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Affiliation(s)
- Rumiko Kofuji
- Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa 920-1192, Japan
| | - Mitsuyasu Hasebe
- National Institute for Basic Biology, National Institutes of Natural Sciences, Okazaki 444-8585, Japan; Department of Basic Biology, Graduate School of Advanced Studies, Okazaki 444-8585, Japan.
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425
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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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426
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Zhou J, Yu F, Wang X, Yang Y, Yu C, Liu H, Cheng Y, Yan C, Chen J. Specific expression of DR5 promoter in rice roots using a tCUP derived promoter-reporter system. PLoS One 2014; 9:e87008. [PMID: 24466314 PMCID: PMC3899362 DOI: 10.1371/journal.pone.0087008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Accepted: 12/15/2013] [Indexed: 11/19/2022] Open
Abstract
Variation of transgene expression caused by either position effect at the insertion site or the promoter/enhancer elements employed for the expression of selectable marker genes has complicated phenotype characterization and caused misinterpretation. We have developed a reporter system in rice to analyze the influence of vector configuration, spacer and selectable marker gene promoter on the expression of the promoterless GUS reporter and DR5 promoter. Our results indicate that a spacer inserted between the reversed 35S promoter and the GUS reporter could reduce leaky expression of the reporter but was unable to block the nonspecific expression of DR5::GUS. Stacking the selectable marker unit in head to tail with the GUS reporter aided the gene specific expression of the GUS reporter under the DR5 promoter even when the 35S promoter is used for expression of the selectable marker. Compared to 35S under this configuration, a quick and distinctive expression of DR5::GUS was observed in the root cap, quiescent center and xylem cells in the root apical meristem by using the tCUP derived promoter (tCUP1) for selection, that is similar to the pattern obtained by a sensitive DR5 variant (DR5rev) in Arabidopsis. These data suggest a conserved property of the tCUP promoter in preventing enhancer-promoter interactions in rice as it does in Arabidopsis, and also demonstrate that an analogous distal auxin maximum exists in roots of rice. Therefore, the tCUP promoter based selection system provides a new strategy for specific expression of transgenes in rice.
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Affiliation(s)
- Jie Zhou
- State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, MOA Key Laboratory for Plant Protection and Biotechnology, Zhejiang Provincial Key Laboratory of Plant Virology, Zhejiang Academy of Agricultural Sciences, Hangzhou, P. R. China
| | - Feibo Yu
- College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, P. R. China
| | - Xuming Wang
- State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, MOA Key Laboratory for Plant Protection and Biotechnology, Zhejiang Provincial Key Laboratory of Plant Virology, Zhejiang Academy of Agricultural Sciences, Hangzhou, P. R. China
| | - Yong Yang
- State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, MOA Key Laboratory for Plant Protection and Biotechnology, Zhejiang Provincial Key Laboratory of Plant Virology, Zhejiang Academy of Agricultural Sciences, Hangzhou, P. R. China
| | - Chulang Yu
- State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, MOA Key Laboratory for Plant Protection and Biotechnology, Zhejiang Provincial Key Laboratory of Plant Virology, Zhejiang Academy of Agricultural Sciences, Hangzhou, P. R. China
| | - Hongjia Liu
- State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, MOA Key Laboratory for Plant Protection and Biotechnology, Zhejiang Provincial Key Laboratory of Plant Virology, Zhejiang Academy of Agricultural Sciences, Hangzhou, P. R. China
| | - Ye Cheng
- State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, MOA Key Laboratory for Plant Protection and Biotechnology, Zhejiang Provincial Key Laboratory of Plant Virology, Zhejiang Academy of Agricultural Sciences, Hangzhou, P. R. China
| | - Chengqi Yan
- State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, MOA Key Laboratory for Plant Protection and Biotechnology, Zhejiang Provincial Key Laboratory of Plant Virology, Zhejiang Academy of Agricultural Sciences, Hangzhou, P. R. China
- * E-mail: (JC); (CY)
| | - Jianping Chen
- State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, MOA Key Laboratory for Plant Protection and Biotechnology, Zhejiang Provincial Key Laboratory of Plant Virology, Zhejiang Academy of Agricultural Sciences, Hangzhou, P. R. China
- * E-mail: (JC); (CY)
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427
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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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428
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Clark NM, de Luis Balaguer MA, Sozzani R. Experimental data and computational modeling link auxin gradient and development in the Arabidopsis root. FRONTIERS IN PLANT SCIENCE 2014; 5:328. [PMID: 25071810 PMCID: PMC4083358 DOI: 10.3389/fpls.2014.00328] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 06/23/2014] [Indexed: 05/04/2023]
Abstract
The presence of an auxin gradient in the Arabidopsis root is crucial for proper root development and importantly, for stem cell niche (SCN) maintenance. Subsequently, developmental pathways in the root SCN regulate the formation of the auxin gradient. Combinations of experimental data and computational modeling enable the identification of pathways involved in establishing and maintaining the auxin gradient. We describe how the predictive power of these computational models is used to find how genes and their interactions tightly control the formation of an auxin maximum in the SCN. In addition, we highlight known connections between signaling pathways involving auxin and controlling patterning and development in Arabidopsis.
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Affiliation(s)
| | | | - Rosangela Sozzani
- *Correspondence: Rosangela Sozzani, Department of Plant and Microbial Biology, North Carolina State University, 2577 Thomas Hall, P. O. Box 7612, Raleigh, NC 27695, USA e-mail:
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429
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Dinneny JR. A gateway with a guard: how the endodermis regulates growth through hormone signaling. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2014; 214:14-9. [PMID: 24268159 DOI: 10.1016/j.plantsci.2013.09.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Revised: 09/18/2013] [Accepted: 09/19/2013] [Indexed: 05/08/2023]
Abstract
The endodermis is a defining feature of plant roots and is most widely studied as a differentially permeable barrier limiting solute uptake from the soil into the vascular stream. Recent work has revealed that this inner cell layer is also an important signaling center for hormone-mediated control of growth. Auxin, gibberellic acid, abscisic acid and strigalactones all appear to depend on the endodermis to regulate root biology and point to this cell type as having important inter-cell layer regulatory activity, as well. In this review I discuss recent work detailing the importance of the endodermis in growth control and how this function is affected during responses to the environment.
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Affiliation(s)
- José R Dinneny
- Carnegie Institution for Science, Department of Plant Biology, Stanford, CA 94305, USA.
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430
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Bartlett ME, Thompson B. Meristem identity and phyllotaxis in inflorescence development. FRONTIERS IN PLANT SCIENCE 2014; 5:508. [PMID: 25352850 PMCID: PMC4196479 DOI: 10.3389/fpls.2014.00508] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 09/10/2014] [Indexed: 05/21/2023]
Abstract
Inflorescence morphology is incredibly diverse. This diversity of form has been a fruitful source of inquiry for plant morphologists for more than a century. Work in the grasses (Poaceae), the tomato family (Solanaceae), and Arabidopsis thaliana (Brassicaceae) has led to a richer understanding of the molecular genetics underlying this diversity. The character of individual meristems, a combination of the number (determinacy) and nature (identity) of the products a meristem produces, is key in the development of plant form. A framework that describes inflorescence development in terms of shifting meristem identities has emerged and garnered empirical support in a number of model systems. We discuss this framework and highlight one important aspect of meristem identity that is often considered in isolation, phyllotaxis. Phyllotaxis refers to the arrangement of lateral organs around a central axis. The development and evolution of phyllotaxis in the inflorescence remains underexplored, but recent work analyzing early inflorescence development in the grasses identified an evolutionary shift in primary branch phyllotaxis in the Pooideae. We discuss the evidence for an intimate connection between meristem identity and phyllotaxis in both the inflorescence and vegetative shoot, and touch on what is known about the establishment of phyllotactic patterns in the meristem. Localized auxin maxima are instrumental in determining the position of lateral primordia. Upstream factors that regulate the position of these maxima remain unclear, and how phyllotactic patterns change over the course of a plant's lifetime and evolutionary time, is largely unknown. A more complete understanding of the molecular underpinnings of phyllotaxis and architectural diversity in inflorescences will require capitalizing on the extensive resources available in existing genetic systems, and developing new model systems that more fully represent the diversity of plant morphology.
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Affiliation(s)
- Madelaine E. Bartlett
- Biology Department, University of Massachusetts AmherstAmherst, MA, USA
- *Correspondence:
| | - Beth Thompson
- Biology Department, East Carolina UniversityGreenville, NC, USA
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431
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Kalve S, De Vos D, Beemster GTS. Leaf development: a cellular perspective. FRONTIERS IN PLANT SCIENCE 2014; 5:362. [PMID: 25132838 PMCID: PMC4116805 DOI: 10.3389/fpls.2014.00362] [Citation(s) in RCA: 142] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2014] [Accepted: 07/07/2014] [Indexed: 05/18/2023]
Abstract
Through its photosynthetic capacity the leaf provides the basis for growth of the whole plant. In order to improve crops for higher productivity and resistance for future climate scenarios, it is important to obtain a mechanistic understanding of leaf growth and development and the effect of genetic and environmental factors on the process. Cells are both the basic building blocks of the leaf and the regulatory units that integrate genetic and environmental information into the developmental program. Therefore, to fundamentally understand leaf development, one needs to be able to reconstruct the developmental pathway of individual cells (and their progeny) from the stem cell niche to their final position in the mature leaf. To build the basis for such understanding, we review current knowledge on the spatial and temporal regulation mechanisms operating on cells, contributing to the formation of a leaf. We focus on the molecular networks that control exit from stem cell fate, leaf initiation, polarity, cytoplasmic growth, cell division, endoreduplication, transition between division and expansion, expansion and differentiation and their regulation by intercellular signaling molecules, including plant hormones, sugars, peptides, proteins, and microRNAs. We discuss to what extent the knowledge available in the literature is suitable to be applied in systems biology approaches to model the process of leaf growth, in order to better understand and predict leaf growth starting with the model species Arabidopsis thaliana.
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Affiliation(s)
- Shweta Kalve
- Laboratory for Molecular Plant Physiology and Biotechnology, Department of Biology, University of Antwerp Antwerp, Belgium
| | - Dirk De Vos
- Laboratory for Molecular Plant Physiology and Biotechnology, Department of Biology, University of Antwerp Antwerp, Belgium ; Department of Mathematics and Computer Science, University of Antwerp Antwerp, Belgium
| | - Gerrit T S Beemster
- Laboratory for Molecular Plant Physiology and Biotechnology, Department of Biology, University of Antwerp Antwerp, Belgium
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432
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Zúñiga-Mayo VM, Reyes-Olalde JI, Marsch-Martinez N, de Folter S. Cytokinin treatments affect the apical-basal patterning of the Arabidopsis gynoecium and resemble the effects of polar auxin transport inhibition. FRONTIERS IN PLANT SCIENCE 2014; 5:191. [PMID: 24860582 PMCID: PMC4030163 DOI: 10.3389/fpls.2014.00191] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 04/23/2014] [Indexed: 05/18/2023]
Abstract
The apical-basal axis of the Arabidopsis gynoecium is established early during development and is divided into four elements from the bottom to the top: the gynophore, the ovary, the style, and the stigma. Currently, it is proposed that the hormone auxin plays a critical role in the correct apical-basal patterning through a concentration gradient from the apical to the basal part of the gynoecium, as chemical inhibition of polar auxin transport through 1-N-naphtylphtalamic acid (NPA) application, severely affects the apical-basal patterning of the gynoecium. In this work, we show that the apical-basal patterning of gynoecia is also sensitive to exogenous cytokinin (benzyl amino purine, BAP) application in a similar way as to NPA. BAP and NPA treatments were performed in different mutant backgrounds where either cytokinin perception or auxin transport and perception were affected. We observed that cytokinin and auxin signaling mutants are hypersensitive to NPA treatment, and auxin transport and signaling mutants are hypersensitive to BAP treatment. BAP effects in apical-basal gynoecium patterning are very similar to the effects of NPA, therefore, it is possible that BAP affects auxin transport in the gynoecium. Indeed, not only the cytokinin-response TCS::GFP marker, but also the auxin efflux carrier PIN1 (PIN1::PIN1:GFP) were both affected in BAP-induced valveless gynoecia, suggesting that the BAP treatment producing the morphological changes has an impact on both in the response pattern to cytokinin and on auxin transport. In summary, we show that cytokinin affects proper apical-basal gynoecium patterning in Arabidopsis in a similar way to the inhibition of polar auxin transport, and that auxin and cytokinin mutants and markers suggest a relation between both hormones in this process.
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Affiliation(s)
- Victor M. Zúñiga-Mayo
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico NacionalIrapuato, México
| | - J. Irepan Reyes-Olalde
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico NacionalIrapuato, México
| | - Nayelli Marsch-Martinez
- Departamento de Biotecnología y Bioquímica, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico NacionalIrapuato, México
| | - Stefan de Folter
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico NacionalIrapuato, México
- *Correspondence: Stefan de Folter, Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Km. 9.6 Libramiento Norte, Carretera Irapuato-León, Irapuato, Guanajuato, CP 36821, México e-mail:
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433
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Chen Y, Aung K, Rolčík J, Walicki K, Friml J, Brandizzi F. Inter-regulation of the unfolded protein response and auxin signaling. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2014; 77:97-107. [PMID: 24180465 PMCID: PMC3981873 DOI: 10.1111/tpj.12373] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Revised: 10/17/2013] [Accepted: 10/21/2013] [Indexed: 05/03/2023]
Abstract
The unfolded protein response (UPR) is a signaling network triggered by overload of protein-folding demand in the endoplasmic reticulum (ER), a condition termed ER stress. The UPR is critical for growth and development; nonetheless, connections between the UPR and other cellular regulatory processes remain largely unknown. Here, we identify a link between the UPR and the phytohormone auxin, a master regulator of plant physiology. We show that ER stress triggers down-regulation of auxin receptors and transporters in Arabidopsis thaliana. We also demonstrate that an Arabidopsis mutant of a conserved ER stress sensor IRE1 exhibits defects in the auxin response and levels. These data not only support that the plant IRE1 is required for auxin homeostasis, they also reveal a species-specific feature of IRE1 in multicellular eukaryotes. Furthermore, by establishing that UPR activation is reduced in mutants of ER-localized auxin transporters, including PIN5, we define a long-neglected biological significance of ER-based auxin regulation. We further examine the functional relationship of IRE1 and PIN5 by showing that an ire1 pin5 triple mutant enhances defects of UPR activation and auxin homeostasis in ire1 or pin5. Our results imply that the plant UPR has evolved a hormone-dependent strategy for coordinating ER function with physiological processes.
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Affiliation(s)
- Yani Chen
- Michigan State University/Department of Energy Plant Research Laboratory and Department of Plant Biology, Michigan State University, East Lansing, MI 48824, USA
| | - Kyaw Aung
- Michigan State University/Department of Energy Plant Research Laboratory and Department of Plant Biology, Michigan State University, East Lansing, MI 48824, USA
| | - Jakub Rolčík
- Laboratory of Growth Regulators, Faculty of Science, Palacký University and Institute of Experimental Botany AS CR, Šlechtitelů 11, 78371 Olomouc, Czech Republic
| | - Kathryn Walicki
- Michigan State University/Department of Energy Plant Research Laboratory and Department of Plant Biology, Michigan State University, East Lansing, MI 48824, USA
| | - Jiří Friml
- Department of Functional Genomics and Proteomics, Central European Institute of Technology (CEITEC), Masaryk University, 62500 Brno, Czech Republic
- Institute of Science and Technology Austria (IST Austria), 3400 Klosterneuburg, Austria
| | - Federica Brandizzi
- Michigan State University/Department of Energy Plant Research Laboratory and Department of Plant Biology, Michigan State University, East Lansing, MI 48824, USA
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434
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Taniguchi M, Nakamura M, Tasaka M, Morita MT. Identification of gravitropic response indicator genes in Arabidopsis inflorescence stems. PLANT SIGNALING & BEHAVIOR 2014; 9:e29570. [PMID: 25763694 PMCID: PMC4203507 DOI: 10.4161/psb.29570] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Differential organ growth during gravitropic response is caused by differential accumulation of auxin, that is, relative higher auxin concentration in lower flanks than in upper flanks of responding organs. Auxin responsive reporter systems such as DR5::GUS and DR5::GFP have usually been used as indicators of gravitropic response in roots and hypocotyls of Arabidopsis. However, in the inflorescence stems, the reporter systems don't work well to monitor gravitropic response. Here, we aim to certify appropriate gravitropic response indicators (GRIs) in inflorescence stems. We performed microarray analysis comparing gene expression profiles between upper and lower flanks of Arabidopsis inflorescence stems after gravistimulation. Thirty genes showed > 2-fold differentially increased expression in lower flanks at 30 min, of which 19 were auxin response genes. We focused on IAA5 and IAA2 and verified whether they are appropriate GRIs by real-time qRT-PCR analyses. Transcript levels of IAA5 and IAA2 were remarkably higher in lower flanks than in upper flanks after gravistimulation. The biased IAA5 or IAA2 expression is disappeared in sgr2-1 mutant which is defective in gravity perception, indicating that gravity perception process is essential for formation of the biased gene expression during gravitropism. IAA5 expression was remarkably increased in lower flanks at 30 min after gravistimulation, whereas IAA2 expression was gradually decreased in upper flanks in a time-dependent manner. Therefore, we conclude that IAA5 is a sensitive GRI to monitor asymmetric auxin signaling caused by gravistimulation in Arabidopsis inflorescence stems.
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Affiliation(s)
- Masatoshi Taniguchi
- Graduate School of Bioagricultural Sciences; Nagoya University; Furo-cho, Chikusa-ku, Nagoya, Japan
| | - Moritaka Nakamura
- Institute of Biochemistry and Biology; Plant Physiology; University of Potsdam; Potsdam-Golm, Germany
| | - Masao Tasaka
- Graduate School of Biological Sciences; Nara Institute of Science and Technology; Takayama, Ikoma, Nara, Japan
| | - Miyo Terao Morita
- Graduate School of Bioagricultural Sciences; Nagoya University; Furo-cho, Chikusa-ku, Nagoya, Japan
- Correspondence to: Miyo Terao Morita,
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435
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Kierzkowski D, Lenhard M, Smith R, Kuhlemeier C. Interaction between meristem tissue layers controls phyllotaxis. Dev Cell 2013; 26:616-28. [PMID: 24091013 DOI: 10.1016/j.devcel.2013.08.017] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Revised: 06/30/2013] [Accepted: 08/22/2013] [Indexed: 01/03/2023]
Abstract
Phyllotaxis and vein formation are among the most conspicuous patterning processes in plants. The expression and polarization of the auxin efflux carrier PIN1 is the earliest marker for both processes, with mathematical models indicating that PIN1 can respond to auxin gradients and/or auxin flux. Here, we use cell-layer-specific PIN1 knockouts and partial complementation of auxin transport mutants to examine the interaction between phyllotactic patterning, which occurs primarily in the L1 surface layer of the meristem, and midvein specification in the inner tissues. We show that PIN1 expression in the L1 is sufficient for correct organ positioning, as long as the L1-specific influx carriers are present. Thus, differentiation of inner tissues can proceed without PIN1 or any of the known polar transporters. On theoretical grounds, we suggest that canalization of auxin flux between an auxin source and an auxin sink may involve facilitated diffusion rather than polar transport.
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Affiliation(s)
- Daniel Kierzkowski
- Institute of Plant Sciences, University of Bern, Bern CH-3013, Switzerland
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436
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Canalization: what the flux? Trends Genet 2013; 30:41-8. [PMID: 24296041 DOI: 10.1016/j.tig.2013.11.001] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Revised: 10/29/2013] [Accepted: 11/01/2013] [Indexed: 01/06/2023]
Abstract
Polarized transport of the hormone auxin plays crucial roles in many processes in plant development. A self-organizing pattern of auxin transport--canalization--is thought to be responsible for vascular patterning and shoot branching regulation in flowering plants. Mathematical modeling has demonstrated that membrane localization of PIN-FORMED (PIN)-family auxin efflux carriers in proportion to net auxin flux can plausibly explain canalization and possibly other auxin transport phenomena. Other plausible models have also been proposed, and there has recently been much interest in producing a unified model of all auxin transport phenomena. However, it is our opinion that lacunae in our understanding of auxin transport biology are now limiting progress in developing the next generation of models. Here we examine several key areas where significant experimental advances are necessary to address both biological and theoretical aspects of auxin transport, including the possibility of a unified transport model.
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437
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Wabnik K, Robert HS, Smith RS, Friml J. Modeling framework for the establishment of the apical-basal embryonic axis in plants. Curr Biol 2013; 23:2513-8. [PMID: 24291090 DOI: 10.1016/j.cub.2013.10.038] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Revised: 09/17/2013] [Accepted: 10/15/2013] [Indexed: 11/17/2022]
Abstract
The apical-basal axis of the early plant embryo determines the body plan of the adult organism. To establish a polarized embryonic axis, plants evolved a unique mechanism that involves directional, cell-to-cell transport of the growth regulator auxin. Auxin transport relies on PIN auxin transporters, whose polar subcellular localization determines the flow directionality. PIN-mediated auxin transport mediates the spatial and temporal activity of the auxin response machinery that contributes to embryo patterning processes, including establishment of the apical (shoot) and basal (root) embryo poles. However, little is known of upstream mechanisms guiding the (re)polarization of auxin fluxes during embryogenesis. Here, we developed a model of plant embryogenesis that correctly generates emergent cell polarities and auxin-mediated sequential initiation of apical-basal axis of plant embryo. The model relies on two precisely localized auxin sources and a feedback between auxin and the polar, subcellular PIN transporter localization. Simulations reproduced PIN polarity and auxin distribution, as well as previously unknown polarization events during early embryogenesis. The spectrum of validated model predictions suggests that our model corresponds to a minimal mechanistic framework for initiation and orientation of the apical-basal axis to guide both embryonic and postembryonic plant development.
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Affiliation(s)
- Krzysztof Wabnik
- Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB) and Department of Plant Biotechnology and Genetics, Ghent University, Technologiepark 927, 9052 Gent, Belgium
| | - Hélène S Robert
- Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB) and Department of Plant Biotechnology and Genetics, Ghent University, Technologiepark 927, 9052 Gent, Belgium; Mendel Centre for Genomics and Proteomics of Plants Systems, Central European Institute of Technology (CEITEC), Masaryk University, 625 00 Brno, Czech Republic
| | - Richard S Smith
- Institute of Plant Sciences, University of Bern, Altenbergrain 21, 3013 Bern, Switzerland; Department of Comparative Development and Genetics, Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, 50829 Köln, Germany
| | - Jiří Friml
- Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB) and Department of Plant Biotechnology and Genetics, Ghent University, Technologiepark 927, 9052 Gent, Belgium; Mendel Centre for Genomics and Proteomics of Plants Systems, Central European Institute of Technology (CEITEC), Masaryk University, 625 00 Brno, Czech Republic; Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria.
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438
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439
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A quantitative ratiometric sensor for time-resolved analysis of auxin dynamics. Sci Rep 2013; 3:2052. [PMID: 23787479 PMCID: PMC3689175 DOI: 10.1038/srep02052] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 06/06/2013] [Indexed: 12/23/2022] Open
Abstract
Time-resolved quantitative analysis of auxin-mediated processes in plant cells is as of yet limited. By applying a synergistic mammalian and plant synthetic biology approach, we have developed a novel ratiometric luminescent biosensor with wide applicability in the study of auxin metabolism, transport, and signalling. The sensitivity and kinetic properties of our genetically encoded biosensor open new perspectives for the analysis of highly complex auxin dynamics in plant growth and development.
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440
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Galvan-Ampudia CS, Julkowska MM, Darwish E, Gandullo J, Korver RA, Brunoud G, Haring MA, Munnik T, Vernoux T, Testerink C. Halotropism is a response of plant roots to avoid a saline environment. Curr Biol 2013; 23:2044-50. [PMID: 24094855 DOI: 10.1016/j.cub.2013.08.042] [Citation(s) in RCA: 187] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Revised: 07/09/2013] [Accepted: 08/13/2013] [Indexed: 01/24/2023]
Abstract
Tropisms represent fascinating examples of how plants respond to environmental signals by adapting their growth and development. Here, a novel tropism is reported, halotropism, allowing plant seedlings to reduce their exposure to salinity by circumventing a saline environment. In response to a salt gradient, Arabidopsis, tomato, and sorghum roots were found to actively prioritize growth away from salinity above following the gravity axis. Directionality of this response is established by an active redistribution of the plant hormone auxin in the root tip, which is mediated by the PIN-FORMED 2 (PIN2) auxin efflux carrier. We show that salt-induced phospholipase D activity stimulates clathrin-mediated endocytosis of PIN2 at the side of the root facing the higher salt concentration. The intracellular relocalization of PIN2 allows for auxin redistribution and for the directional bending of the root away from the higher salt concentration. Our results thus identify a cellular pathway essential for the integration of environmental cues with auxin-regulated root growth that likely plays a key role in plant adaptative responses to salt stress.
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Affiliation(s)
- Carlos S Galvan-Ampudia
- Section of Plant Physiology, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, the Netherlands
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441
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Peer WA. From perception to attenuation: auxin signalling and responses. CURRENT OPINION IN PLANT BIOLOGY 2013; 16:561-8. [PMID: 24004572 DOI: 10.1016/j.pbi.2013.08.003] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Revised: 08/09/2013] [Accepted: 08/14/2013] [Indexed: 05/10/2023]
Abstract
The plant hormone auxin is essential for growth, development, and responses to environmental factors. Recently, Auxin Binding Protein 1 was shown to mediate non-transcriptional auxin signalling at the cell periphery. This has provoked reexamination of the paradigm that all auxin perception is intracellular and is mediated by the TIR1/AFB-Aux/IAA co-receptors for which auxin functions as a concentration-dependent molecular glue. Further, another F-box protein, SKP2a, was shown to bind auxin in the same way as TIR1/AFB, which provides a link to the role of auxin in the cell cycle. New work on auxin signalling and homeostasis include D6 PROTEIN KINASE activation of PINFORMED (PIN) auxin carriers, ROP-GTPase mediation of PIN localization, endoplasmic reticulum localization PIN and PIN-LIKES auxin carriers, and auxin biosynthesis and metabolism.
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Affiliation(s)
- Wendy Ann Peer
- Department of Environmental Science and Technology, University of Maryland, 5138 Plant Science Building, College Park, MD 20742, USA; Department of Plant Science and Landscape Architecture, University of Maryland, 5138 Plant Science Building, College Park, MD 20742, USA.
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442
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Zhang KX, Xu HH, Yuan TT, Zhang L, Lu YT. Blue-light-induced PIN3 polarization for root negative phototropic response in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 76:308-21. [PMID: 23888933 DOI: 10.1111/tpj.12298] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Revised: 06/04/2013] [Accepted: 07/12/2013] [Indexed: 05/04/2023]
Abstract
Root negative phototropism is an important response in plants. Although blue light is known to mediate this response, the cellular and molecular mechanisms underlying root negative phototropism remain unclear. Here, we report that the auxin efflux carrier PIN-FORMED (PIN) 3 is involved in asymmetric auxin distribution and root negative phototropism. Unilateral blue-light illumination polarized PIN3 to the outer lateral membrane of columella cells at the illuminated root side, and increased auxin activity at the illuminated side of roots, where auxin promotes growth and causes roots bending away from the light source. Furthermore, root negative phototropic response and blue-light-induced PIN3 polarization were modulated by a brefeldin A-sensitive, GNOM-dependent, trafficking pathway and by phot1-regulated PINOID (PID)/PROTEIN PHOSPHATASE 2A (PP2A) activity. Our results indicate that blue-light-induced PIN3 polarization is needed for asymmetric auxin distribution during root negative phototropic response.
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Affiliation(s)
- Kun-Xiao Zhang
- Key Lab of MOE for Plant Development, College of Life Sciences, Wuhan University, Wuhan, 430072, China
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443
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Uga Y, Sugimoto K, Ogawa S, Rane J, Ishitani M, Hara N, Kitomi Y, Inukai Y, Ono K, Kanno N, Inoue H, Takehisa H, Motoyama R, Nagamura Y, Wu J, Matsumoto T, Takai T, Okuno K, Yano M. Control of root system architecture by DEEPER ROOTING 1 increases rice yield under drought conditions. Nat Genet 2013; 45:1097-102. [PMID: 23913002 DOI: 10.1038/ng.2725] [Citation(s) in RCA: 659] [Impact Index Per Article: 59.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Accepted: 07/15/2013] [Indexed: 01/27/2023]
Abstract
The genetic improvement of drought resistance is essential for stable and adequate crop production in drought-prone areas. Here we demonstrate that alteration of root system architecture improves drought avoidance through the cloning and characterization of DEEPER ROOTING 1 (DRO1), a rice quantitative trait locus controlling root growth angle. DRO1 is negatively regulated by auxin and is involved in cell elongation in the root tip that causes asymmetric root growth and downward bending of the root in response to gravity. Higher expression of DRO1 increases the root growth angle, whereby roots grow in a more downward direction. Introducing DRO1 into a shallow-rooting rice cultivar by backcrossing enabled the resulting line to avoid drought by increasing deep rooting, which maintained high yield performance under drought conditions relative to the recipient cultivar. Our experiments suggest that control of root system architecture will contribute to drought avoidance in crops.
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Affiliation(s)
- Yusaku Uga
- National Institute of Agrobiological Sciences, Tsukuba, Japan.
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444
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Benitez-Alfonso Y, Faulkner C, Pendle A, Miyashima S, Helariutta Y, Maule A. Symplastic intercellular connectivity regulates lateral root patterning. Dev Cell 2013; 26:136-47. [PMID: 23850190 DOI: 10.1016/j.devcel.2013.06.010] [Citation(s) in RCA: 158] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Revised: 04/05/2013] [Accepted: 06/11/2013] [Indexed: 11/18/2022]
Abstract
Cell-to-cell communication coordinates the behavior of individual cells to establish organ patterning and development. Although mobile signals are known to be important in lateral root development, the role of plasmodesmata (PD)-mediated transport in this process has not been investigated. Here, we show that changes in symplastic connectivity accompany and regulate lateral root organogenesis in Arabidopsis. This connectivity is dependent upon callose deposition around PD affecting molecular flux through the channel. Two plasmodesmal-localized β-1,3 glucanases (PdBGs) were identified that regulate callose accumulation and the number and distribution of lateral roots. The fundamental role of PD-associated callose in this process was illustrated by the induction of similar phenotypes in lines with altered callose turnover. Our results show that regulation of callose and cell-to-cell connectivity is critical in determining the pattern of lateral root formation, which influences root architecture and optimal plant performance.
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445
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Fozard JA, Lucas M, King JR, Jensen OE. Vertex-element models for anisotropic growth of elongated plant organs. FRONTIERS IN PLANT SCIENCE 2013; 4:233. [PMID: 23847638 PMCID: PMC3706750 DOI: 10.3389/fpls.2013.00233] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Accepted: 06/13/2013] [Indexed: 05/09/2023]
Abstract
New tools are required to address the challenge of relating plant hormone levels, hormone responses, wall biochemistry and wall mechanical properties to organ-scale growth. Current vertex-based models (applied in other contexts) can be unsuitable for simulating the growth of elongated organs such as roots because of the large aspect ratio of the cells, and these models fail to capture the mechanical properties of cell walls in sufficient detail. We describe a vertex-element model which resolves individual cells and includes anisotropic non-linear viscoelastic mechanical properties of cell walls and cell division whilst still being computationally efficient. We show that detailed consideration of the cell walls in the plane of a 2D simulation is necessary when cells have large aspect ratio, such as those in the root elongation zone of Arabidopsis thaliana, in order to avoid anomalous transverse swelling. We explore how differences in the mechanical properties of cells across an organ can result in bending and how cellulose microfibril orientation affects macroscale growth. We also demonstrate that the model can be used to simulate growth on realistic geometries, for example that of the primary root apex, using moderate computational resources. The model shows how macroscopic root shape can be sensitive to fine-scale cellular geometries.
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Affiliation(s)
- John A. Fozard
- Agricultural and Environmental Sciences, Centre for Plant Integrative Biology, School of Biosciences, University of NottinghamLeics, UK
| | - Mikaël Lucas
- Institut de Recherche pour le Développement, UMR DIADEMontpellier, France
| | - John R. King
- Agricultural and Environmental Sciences, Centre for Plant Integrative Biology, School of Biosciences, University of NottinghamLeics, UK
- School of Mathematical Sciences, University of NottinghamNottingham, UK
| | - Oliver E. Jensen
- Agricultural and Environmental Sciences, Centre for Plant Integrative Biology, School of Biosciences, University of NottinghamLeics, UK
- School of Mathematics, University of ManchesterManchester, UK
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446
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Del Bianco M, Giustini L, Sabatini S. Spatiotemporal changes in the role of cytokinin during root development. THE NEW PHYTOLOGIST 2013; 199:324-338. [PMID: 23692218 DOI: 10.1111/nph.12338] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Accepted: 04/12/2013] [Indexed: 05/07/2023]
Abstract
The root is a dynamic system whose structure is regulated by a complex network of interactions between hormones. The primary root meristem is specified in the embryo. After germination, the primary root meristem grows and then reaches a final size that will be maintained during the life of the plant. Subsequently, secondary structures such as lateral roots and root nodules form via the re-specification of differentiated cells. Cytokinin plays key roles in the regulation of root development. Down-regulation of the cytokinin response is required for the specification of a new stem cell niche, during both embryo and lateral root development. In the root meristem, cytokinin signalling regulates the longitudinal zonation of the meristem by controlling cell differentiation. Moreover, cytokinin regulates radial patterning of root vasculature by promoting protophloem cell identity and by spatially inhibiting protoxylem formation. In this review, an effort is made to describe the known details of the role of cytokinin during root development, taking into account also the interactions between cytokinin and other hormones. Attention is given on the dynamicity of cytokinin signalling output during different developmental events. Indeed, there is much evidence that the effects of cytokinin change as organs grow, underlining the importance of the spatiotemporal specificity of cytokinin signalling.
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Affiliation(s)
- Marta Del Bianco
- Laboratory of Functional Genomics and Proteomics of Model Systems, Dipartimento di Biologia e Biotecnologie, Università di Roma, Sapienza - via dei Sardi, 70-00185, Rome, Italy
| | - Leonardo Giustini
- Laboratory of Functional Genomics and Proteomics of Model Systems, Dipartimento di Biologia e Biotecnologie, Università di Roma, Sapienza - via dei Sardi, 70-00185, Rome, Italy
| | - Sabrina Sabatini
- Laboratory of Functional Genomics and Proteomics of Model Systems, Dipartimento di Biologia e Biotecnologie, Università di Roma, Sapienza - via dei Sardi, 70-00185, Rome, Italy
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447
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Feng Z, Zhang W, Xu J, Gauron C, Ducos B, Vriz S, Volovitch M, Jullien L, Weiss S, Bensimon D. Optical control and study of biological processes at the single-cell level in a live organism. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2013; 76:072601. [PMID: 23764902 PMCID: PMC3736146 DOI: 10.1088/0034-4885/76/7/072601] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Living organisms are made of cells that are capable of responding to external signals by modifying their internal state and subsequently their external environment. Revealing and understanding the spatio-temporal dynamics of these complex interaction networks is the subject of a field known as systems biology. To investigate these interactions (a necessary step before understanding or modelling them) one needs to develop means to control or interfere spatially and temporally with these processes and to monitor their response on a fast timescale (< minute) and with single-cell resolution. In 2012, an EMBO workshop on 'single-cell physiology' (organized by some of us) was held in Paris to discuss those issues in the light of recent developments that allow for precise spatio-temporal perturbations and observations. This review will be largely based on the investigations reported there. We will first present a non-exhaustive list of examples of cellular interactions and developmental pathways that could benefit from these new approaches. We will review some of the novel tools that have been developed for the observation of cellular activity and then discuss the recent breakthroughs in optical super-resolution microscopy that allow for optical observations beyond the diffraction limit. We will review the various means to photo-control the activity of biomolecules, which allow for local perturbations of physiological processes. We will end up this review with a report on the current status of optogenetics: the use of photo-sensitive DNA-encoded proteins as sensitive reporters and efficient actuators to perturb and monitor physiological processes.
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Affiliation(s)
- Zhiping Feng
- Department of Molecular, Cellular and Integrative Physiology, University of California Los Angeles, Los Angeles, CA 90095, USA
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448
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Jung JKH, McCouch S. Getting to the roots of it: Genetic and hormonal control of root architecture. FRONTIERS IN PLANT SCIENCE 2013; 4:186. [PMID: 23785372 PMCID: PMC3685011 DOI: 10.3389/fpls.2013.00186] [Citation(s) in RCA: 145] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Accepted: 05/22/2013] [Indexed: 05/17/2023]
Abstract
Root system architecture (RSA) - the spatial configuration of a root system - is an important developmental and agronomic trait, with implications for overall plant architecture, growth rate and yield, abiotic stress resistance, nutrient uptake, and developmental plasticity in response to environmental changes. Root architecture is modulated by intrinsic, hormone-mediated pathways, intersecting with pathways that perceive and respond to external, environmental signals. The recent development of several non-invasive 2D and 3D root imaging systems has enhanced our ability to accurately observe and quantify architectural traits on complex whole-root systems. Coupled with the powerful marker-based genotyping and sequencing platforms currently available, these root phenotyping technologies lend themselves to large-scale genome-wide association studies, and can speed the identification and characterization of the genes and pathways involved in root system development. This capability provides the foundation for examining the contribution of root architectural traits to the performance of crop varieties in diverse environments. This review focuses on our current understanding of the genes and pathways involved in determining RSA in response to both intrinsic and extrinsic (environmental) response pathways, and provides a brief overview of the latest root system phenotyping technologies and their potential impact on elucidating the genetic control of root development in plants.
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Affiliation(s)
| | - Susan McCouch
- Department of Plant Breeding and Genetics, Cornell UniversityIthaca, NY, USA
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449
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Jones AM, Grossmann G, Danielson JÅ, Sosso D, Chen LQ, Ho CH, Frommer WB. In vivo biochemistry: applications for small molecule biosensors in plant biology. CURRENT OPINION IN PLANT BIOLOGY 2013; 16:389-95. [PMID: 23587939 PMCID: PMC3679211 DOI: 10.1016/j.pbi.2013.02.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Revised: 02/22/2013] [Accepted: 02/22/2013] [Indexed: 05/02/2023]
Abstract
Revolutionary new technologies, namely in the areas of DNA sequencing and molecular imaging, continue to impact new discoveries in plant science and beyond. For decades we have been able to determine properties of enzymes, receptors and transporters in vitro or in heterologous systems, and more recently been able to analyze their regulation at the transcriptional level, to use GFP reporters for obtaining insights into cellular and subcellular localization, and tp measure ion and metabolite levels with unprecedented precision using mass spectrometry. However, we lack key information on the location and dynamics of the substrates of enzymes, receptors and transporters, and on the regulation of these proteins in their cellular environment. Such information can now be obtained by transitioning from in vitro to in vivo biochemistry using biosensors. Genetically encoded fluorescent protein-based sensors for ion and metabolite dynamics provide highly resolved spatial and temporal information, and are complemented by sensors for pH, redox, voltage, and tension. They serve as powerful tools for identifying missing processes (e.g., glucose transport across ER membranes), components (e.g., SWEET sugar transporters for cellular sugar efflux), and signaling networks (e.g., from systematic screening of mutants that affect sugar transport or cytosolic and vacuolar pH). Combined with the knowledge of properties of enzymes and transporters and their interactions with the regulatory machinery, biosensors promise to be key diagnostic tools for systems and synthetic biology.
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Affiliation(s)
- Alexander M Jones
- Carnegie Institution for Science, Department of Plant Biology, 260 Panama St., Stanford, CA 94305, USA
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450
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Laskowski M. Lateral root initiation is a probabilistic event whose frequency is set by fluctuating levels of auxin response. JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:2609-17. [PMID: 23709673 DOI: 10.1093/jxb/ert155] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The locations in which lateral roots arise are determined by local peaks of auxin response driven by whole-plant physiology. The architecture of a plant root system adapts it to the conditions in which it grows: large shoot systems demand large root systems, and growth in soils that have low or patchy nutrient distributions is often best managed by non-uniform patterns of root branching. It is not surprising then that the regulation of lateral root spacing is responsive to a wide array of stimuli. Molecular genetic studies have outlined a mechanism by which multiple modules of auxin response in specific cell types drive lateral root initiation. These peaks of auxin responsiveness are functionally controlled by the growth of the plant and the changing environmental conditions it experiences. Thus, the process of lateral root initiation, which depends on strong local auxin response, is globally mediated.
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Affiliation(s)
- Marta Laskowski
- Department of Biology, Oberlin College, Oberlin, OH 44074, USA.
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