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Scarpella E. Leaf Vein Patterning. ANNUAL REVIEW OF PLANT BIOLOGY 2024; 75:377-398. [PMID: 38382907 DOI: 10.1146/annurev-arplant-062923-030348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
Leaves form veins whose patterns vary from a single vein running the length of the leaf to networks of staggering complexity where huge numbers of veins connect to other veins at both ends. For the longest time, vein formation was thought to be controlled only by the polar, cell-to-cell transport of the plant hormone auxin; recent evidence suggests that is not so. Instead, it turns out that vein patterning features are best accounted for by a combination of polar auxin transport, facilitated auxin diffusion through plasmodesma intercellular channels, and auxin signal transduction-though the latter's precise contribution remains unclear. Equally unclear remain the sites of auxin production during leaf development, on which that vein patterning mechanism ought to depend. Finally, whether that vein patterning mechanism can account for the variety of vein arrangements found in nature remains unknown. Addressing those questions will be the exciting challenge of future research.
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Affiliation(s)
- Enrico Scarpella
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada;
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2
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Vlad D, Zaidem M, Perico C, Sedelnikova O, Bhattacharya S, Langdale JA. The WIP6 transcription factor TOO MANY LATERALS specifies vein type in C 4 and C 3 grass leaves. Curr Biol 2024; 34:1670-1686.e10. [PMID: 38531358 DOI: 10.1016/j.cub.2024.03.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 02/04/2024] [Accepted: 03/07/2024] [Indexed: 03/28/2024]
Abstract
Grass leaves are invariantly strap shaped with an elongated distal blade and a proximal sheath that wraps around the stem. Underpinning this shape is a scaffold of leaf veins, most of which extend in parallel along the proximo-distal leaf axis. Differences between species are apparent both in the vein types that develop and in the distance between veins across the medio-lateral leaf axis. A prominent engineering goal is to increase vein density in leaves of C3 photosynthesizing species to facilitate the introduction of the more efficient C4 pathway. Here, we discover that the WIP6 transcription factor TOO MANY LATERALS (TML) specifies vein rank in both maize (C4) and rice (C3). Loss-of-function tml mutations cause large lateral veins to develop in positions normally occupied by smaller intermediate veins, and TML transcript localization in wild-type leaves is consistent with a role in suppressing lateral vein development in procambial cells that form intermediate veins. Attempts to manipulate TML function in rice were unsuccessful because transgene expression was silenced, suggesting that precise TML expression is essential for shoot viability. This finding may reflect the need to prevent the inappropriate activation of downstream targets or, given that transcriptome analysis revealed altered cytokinin and auxin signaling profiles in maize tml mutants, the need to prevent local or general hormonal imbalances. Importantly, rice tml mutants display an increased occupancy of veins in the leaf, providing a step toward an anatomical chassis for C4 engineering. Collectively, a conserved mechanism of vein rank specification in grass leaves has been revealed.
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Affiliation(s)
- Daniela Vlad
- Department of Biology, University of Oxford, South Parks Rd, Oxford OX1 3RB, UK
| | - Maricris Zaidem
- Department of Biology, University of Oxford, South Parks Rd, Oxford OX1 3RB, UK
| | - Chiara Perico
- Department of Biology, University of Oxford, South Parks Rd, Oxford OX1 3RB, UK
| | - Olga Sedelnikova
- Department of Biology, University of Oxford, South Parks Rd, Oxford OX1 3RB, UK
| | - Samik Bhattacharya
- Resolve BioSciences GmbH, Alfred-Nobel-Straße 10, 40789 Monheim am Rhein, Germany
| | - Jane A Langdale
- Department of Biology, University of Oxford, South Parks Rd, Oxford OX1 3RB, UK.
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3
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Scarpella E. Axes and polarities in leaf vein formation. PLANT PHYSIOLOGY 2023; 193:112-124. [PMID: 37261944 DOI: 10.1093/plphys/kiad321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 04/21/2023] [Accepted: 05/04/2023] [Indexed: 06/03/2023]
Abstract
For multicellular organisms to develop, cells must grow, divide, and differentiate along preferential or exclusive orientations or directions. Moreover, those orientations, or axes, and directions, or polarities, must be coordinated between cells within and between tissues. Therefore, how axes and polarities are coordinated between cells is a key question in biology. In animals, such coordination mainly depends on cell migration and direct interaction between proteins protruding from the plasma membrane. Both cell movements and direct cell-cell interactions are prevented in plants by cell walls that surround plant cells and keep them apart and in place. Therefore, plants have evolved unique mechanisms to coordinate their cell axes and polarities. Here I will discuss evidence suggesting that understanding how leaf veins form may uncover those unique mechanisms. Indeed, unlike previously thought, the cell-to-cell polar transport of the plant hormone auxin along developing veins cannot account for many features of vein patterning. Instead, those features can be accounted for by models of vein patterning that combine polar auxin transport with auxin diffusion through plasmodesmata along the axis of developing veins. Though it remains unclear whether such a combination of polar transport and axial diffusion of auxin can account for the formation of the variety of vein patterns found in plant leaves, evidence suggests that such a combined mechanism may control plant developmental processes beyond vein patterning.
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Affiliation(s)
- Enrico Scarpella
- Department of Biological Sciences, University of Alberta, CW-405 Biological Sciences Building, Edmonton, AB T6G 2E9, Canada
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4
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Liu Q, Teng S, Deng C, Wu S, Li H, Wang Y, Wu J, Cui X, Zhang Z, Quick WP, Brutnell TP, Sun X, Lu T. SHORT ROOT and INDETERMINATE DOMAIN family members govern PIN-FORMED expression to regulate minor vein differentiation in rice. THE PLANT CELL 2023; 35:2848-2870. [PMID: 37154077 PMCID: PMC10396363 DOI: 10.1093/plcell/koad125] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 03/08/2023] [Accepted: 04/02/2023] [Indexed: 05/10/2023]
Abstract
C3 and C4 grasses directly and indirectly provide the vast majority of calories to the human diet, yet our understanding of the molecular mechanisms driving photosynthetic productivity in grasses is largely unexplored. Ground meristem cells divide to form mesophyll or vascular initial cells early in leaf development in C3 and C4 grasses. Here we define a genetic circuit composed of SHORT ROOT (SHR), INDETERMINATE DOMAIN (IDD), and PIN-FORMED (PIN) family members that specifies vascular identify and ground cell proliferation in leaves of both C3 and C4 grasses. Ectopic expression and loss-of-function mutant studies of SHR paralogs in the C3 plant Oryza sativa (rice) and the C4 plant Setaria viridis (green millet) revealed the roles of these genes in both minor vein formation and ground cell differentiation. Genetic and in vitro studies further suggested that SHR regulates this process through its interactions with IDD12 and 13. We also revealed direct interactions of these IDD proteins with a putative regulatory element within the auxin transporter gene PIN5c. Collectively, these findings indicate that a SHR-IDD regulatory circuit mediates auxin transport by negatively regulating PIN expression to modulate minor vein patterning in the grasses.
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Affiliation(s)
- Qiming Liu
- Biotechnology Research Institute (BRI), Chinese Academy of Agricultural Sciences (CAAS), Beijing 100081, China
- Joint Laboratory for Photosynthesis Enhancement and C4 Rice Development, BRI, CAAS, Beijing 100081, China
| | - Shouzhen Teng
- Biotechnology Research Institute (BRI), Chinese Academy of Agricultural Sciences (CAAS), Beijing 100081, China
- Joint Laboratory for Photosynthesis Enhancement and C4 Rice Development, BRI, CAAS, Beijing 100081, China
| | - Chen Deng
- Joint Laboratory for Photosynthesis Enhancement and C4 Rice Development, BRI, CAAS, Beijing 100081, China
| | - Suting Wu
- Biotechnology Research Institute (BRI), Chinese Academy of Agricultural Sciences (CAAS), Beijing 100081, China
- Joint Laboratory for Photosynthesis Enhancement and C4 Rice Development, BRI, CAAS, Beijing 100081, China
| | - Haoshu Li
- Biotechnology Research Institute (BRI), Chinese Academy of Agricultural Sciences (CAAS), Beijing 100081, China
- Joint Laboratory for Photosynthesis Enhancement and C4 Rice Development, BRI, CAAS, Beijing 100081, China
| | - Yanwei Wang
- Joint Laboratory for Photosynthesis Enhancement and C4 Rice Development, BRI, CAAS, Beijing 100081, China
| | - Jinxia Wu
- Biotechnology Research Institute (BRI), Chinese Academy of Agricultural Sciences (CAAS), Beijing 100081, China
- Joint Laboratory for Photosynthesis Enhancement and C4 Rice Development, BRI, CAAS, Beijing 100081, China
| | - Xuean Cui
- Biotechnology Research Institute (BRI), Chinese Academy of Agricultural Sciences (CAAS), Beijing 100081, China
- Joint Laboratory for Photosynthesis Enhancement and C4 Rice Development, BRI, CAAS, Beijing 100081, China
| | - Zhiguo Zhang
- Biotechnology Research Institute (BRI), Chinese Academy of Agricultural Sciences (CAAS), Beijing 100081, China
- Joint Laboratory for Photosynthesis Enhancement and C4 Rice Development, BRI, CAAS, Beijing 100081, China
| | - William Paul Quick
- Joint Laboratory for Photosynthesis Enhancement and C4 Rice Development, BRI, CAAS, Beijing 100081, China
- C4 Rice Centre, International Rice Research Institute, Los Banos, Laguna 4030, Philippines
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
| | - Thomas P Brutnell
- Joint Laboratory for Photosynthesis Enhancement and C4 Rice Development, BRI, CAAS, Beijing 100081, China
| | - Xuehui Sun
- Biotechnology Research Institute (BRI), Chinese Academy of Agricultural Sciences (CAAS), Beijing 100081, China
- Joint Laboratory for Photosynthesis Enhancement and C4 Rice Development, BRI, CAAS, Beijing 100081, China
| | - Tiegang Lu
- Biotechnology Research Institute (BRI), Chinese Academy of Agricultural Sciences (CAAS), Beijing 100081, China
- Joint Laboratory for Photosynthesis Enhancement and C4 Rice Development, BRI, CAAS, Beijing 100081, China
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5
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Linh NM, Scarpella E. Leaf vein patterning is regulated by the aperture of plasmodesmata intercellular channels. PLoS Biol 2022; 20:e3001781. [PMID: 36166438 PMCID: PMC9514613 DOI: 10.1371/journal.pbio.3001781] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 08/03/2022] [Indexed: 02/03/2023] Open
Abstract
To form tissue networks, animal cells migrate and interact through proteins protruding from their plasma membranes. Plant cells can do neither, yet plants form vein networks. How plants do so is unclear, but veins are thought to form by the coordinated action of the polar transport and signal transduction of the plant hormone auxin. However, plants inhibited in both pathways still form veins. Patterning of vascular cells into veins is instead prevented in mutants lacking the function of the GNOM (GN) regulator of auxin transport and signaling, suggesting the existence of at least one more GN-dependent vein-patterning pathway. Here we show that in Arabidopsis such a pathway depends on the movement of auxin or an auxin-dependent signal through plasmodesmata (PDs) intercellular channels. PD permeability is high where veins are forming, lowers between veins and nonvascular tissues, but remains high between vein cells. Impaired ability to regulate PD aperture leads to defects in auxin transport and signaling, ultimately leading to vein patterning defects that are enhanced by inhibition of auxin transport or signaling. GN controls PD aperture regulation, and simultaneous inhibition of auxin signaling, auxin transport, and regulated PD aperture phenocopies null gn mutants. Therefore, veins are patterned by the coordinated action of three GN-dependent pathways: auxin signaling, polar auxin transport, and movement of auxin or an auxin-dependent signal through PDs. Such a mechanism of tissue network formation is unprecedented in multicellular organisms. How do plants form vein networks, in the absence of cellular migration or direct cell-cell interaction? This study shows that a GNOM-dependent combination of polar auxin transport, auxin signal transduction, and movement of an auxin signal through plasmodesmata patterns leaf vascular cells into veins.
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Affiliation(s)
- Nguyen Manh Linh
- Department of Biological Sciences, University of Alberta, Edmonton, Canada
| | - Enrico Scarpella
- Department of Biological Sciences, University of Alberta, Edmonton, Canada
- * E-mail:
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6
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Perico C, Tan S, Langdale JA. Developmental regulation of leaf venation patterns: monocot versus eudicots and the role of auxin. THE NEW PHYTOLOGIST 2022; 234:783-803. [PMID: 35020214 PMCID: PMC9994446 DOI: 10.1111/nph.17955] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 12/14/2021] [Indexed: 06/14/2023]
Abstract
Organisation and patterning of the vascular network in land plants varies in different taxonomic, developmental and environmental contexts. In leaves, the degree of vascular strand connectivity influences both light and CO2 harvesting capabilities as well as hydraulic capacity. As such, developmental mechanisms that regulate leaf venation patterning have a direct impact on physiological performance. Development of the leaf venation network requires the specification of procambial cells within the ground meristem of the primordium and subsequent proliferation and differentiation of the procambial lineage to form vascular strands. An understanding of how diverse venation patterns are manifest therefore requires mechanistic insight into how procambium is dynamically specified in a growing leaf. A role for auxin in this process was identified many years ago, but questions remain. In this review we first provide an overview of the diverse venation patterns that exist in land plants, providing an evolutionary perspective. We then focus on the developmental regulation of leaf venation patterns in angiosperms, comparing patterning in eudicots and monocots, and the role of auxin in each case. Although common themes emerge, we conclude that the developmental mechanisms elucidated in eudicots are unlikely to fully explain how parallel venation patterns in monocot leaves are elaborated.
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Affiliation(s)
- Chiara Perico
- Department of Plant SciencesUniversity of OxfordSouth Parks RdOxfordOX1 3RBUK
| | - Sovanna Tan
- Department of Plant SciencesUniversity of OxfordSouth Parks RdOxfordOX1 3RBUK
| | - Jane A. Langdale
- Department of Plant SciencesUniversity of OxfordSouth Parks RdOxfordOX1 3RBUK
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7
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Lv Q, Li X, Fan B, Zhu C, Chen Z. The Cellular and Subcellular Organization of the Glucosinolate–Myrosinase System against Herbivores and Pathogens. Int J Mol Sci 2022; 23:ijms23031577. [PMID: 35163500 PMCID: PMC8836197 DOI: 10.3390/ijms23031577] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2022] [Revised: 01/26/2022] [Accepted: 01/27/2022] [Indexed: 01/01/2023] Open
Abstract
Glucosinolates are an important class of secondary metabolites in Brassicales plants with a critical role in chemical defense. Glucosinolates are chemically inactive but can be hydrolyzed by myrosinases to produce a range of chemically active compounds toxic to herbivores and pathogens, thereby constituting the glucosinolate–myrosinase defense system or the mustard oil bomb. During the evolution, Brassicales plants have developed not only complex biosynthetic pathways for production of a large number of glucosinolate structures but also different classes of myrosinases that differ in catalytic mechanisms and substrate specificity. Studies over the past several decades have made important progress in the understanding of the cellular and subcellular organization of the glucosinolate–myrosinase system for rapid and timely detonation of the mustard oil bomb upon tissue damage after herbivore feeding and pathogen infection. Progress has also been made in understanding the mechanisms that herbivores and pathogens have evolved to counter the mustard oil bomb. In this review, we summarize our current understanding of the function and organization of the glucosinolate–myrosinase system in Brassicales plants and discuss both the progresses and future challenges in addressing this complex defense system as an excellent model for analyzing plant chemical defense.
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Affiliation(s)
- Qiaoqiao Lv
- College of Life Sciences, China Jiliang University, Hangzhou 310018, China; (Q.L.); (X.L.)
| | - Xifeng Li
- College of Life Sciences, China Jiliang University, Hangzhou 310018, China; (Q.L.); (X.L.)
| | - Baofang Fan
- Purdue Center for Plant Biology, Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907-2054, USA;
| | - Cheng Zhu
- College of Life Sciences, China Jiliang University, Hangzhou 310018, China; (Q.L.); (X.L.)
- Correspondence: (C.Z.); (Z.C.); Tel.: +86-571-8683-6090 (C.Z.); +1-765-494-4657 (Z.C.)
| | - Zhixiang Chen
- College of Life Sciences, China Jiliang University, Hangzhou 310018, China; (Q.L.); (X.L.)
- Purdue Center for Plant Biology, Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907-2054, USA;
- Correspondence: (C.Z.); (Z.C.); Tel.: +86-571-8683-6090 (C.Z.); +1-765-494-4657 (Z.C.)
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8
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Control of vein-forming, striped gene expression by auxin signaling. BMC Biol 2021; 19:213. [PMID: 34556094 PMCID: PMC8461865 DOI: 10.1186/s12915-021-01143-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 09/03/2021] [Indexed: 11/10/2022] Open
Abstract
Background Activation of gene expression in striped domains is a key building block of biological patterning, from the recursive formation of veins in plant leaves to that of ribs and vertebrae in our bodies. In animals, gene expression is activated in striped domains by the differential affinity of broadly expressed transcription factors for their target genes and the combinatorial interaction between such target genes. In plants, how gene expression is activated in striped domains is instead unknown. We address this question for the broadly expressed MONOPTEROS (MP) transcription factor and its target gene ARABIDOPSIS THALIANA HOMEOBOX FACTOR8 (ATHB8). Results We find that ATHB8 promotes vein formation and that such vein-forming function depends on both levels of ATHB8 expression and width of ATHB8 expression domains. We further find that ATHB8 expression is activated in striped domains by a combination of (1) activation of ATHB8 expression through binding of peak levels of MP to a low-affinity MP-binding site in the ATHB8 promoter and (2) repression of ATHB8 expression by MP target genes of the AUXIN/INDOLE-3-ACETIC-ACID-INDUCIBLE family. Conclusions Our findings suggest that a common regulatory logic controls activation of gene expression in striped domains in both plants and animals despite the independent evolution of their multicellularity. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-021-01143-9.
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Yanagisawa M, Poitout A, Otegui MS. Arabidopsis vascular complexity and connectivity controls PIN-FORMED1 dynamics and lateral vein patterning during embryogenesis. Development 2021; 148:dev197210. [PMID: 34137447 DOI: 10.1242/dev.197210] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 06/14/2021] [Indexed: 11/20/2022]
Abstract
Arabidopsis VASCULATURE COMPLEXITY AND CONNECTIVITY (VCC) is a plant-specific transmembrane protein that controls the development of veins in cotyledons. Here, we show that the expression and localization of the auxin efflux carrier PIN-FORMED1 (PIN1) is altered in vcc developing cotyledons and that overexpression of PIN1-GFP partially rescues vascular defects of vcc in a dosage-dependent manner. Genetic analyses suggest that VCC and PINOID (PID), a kinase that regulates PIN1 polarity, are both required for PIN1-mediated control of vasculature development. VCC expression is upregulated by auxin, likely as part of a positive feedback loop for the progression of vascular development. VCC and PIN1 localized to the plasma membrane in pre-procambial cells but were actively redirected to vacuoles in procambial cells for degradation. In the vcc mutant, PIN1 failed to properly polarize in pre-procambial cells during the formation of basal strands, and instead, it was prematurely degraded in vacuoles. VCC plays a role in the localization and stability of PIN1, which is crucial for the transition of pre-procambial cells into procambial cells that are involved in the formation of basal lateral strands in embryonic cotyledons.
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Affiliation(s)
- Makoto Yanagisawa
- Department of Botany, University of Wisconsin-Madison, Madison, WI 53706, USA
- Center for Quantitative Cell Imaging, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Arthur Poitout
- Department of Botany, University of Wisconsin-Madison, Madison, WI 53706, USA
- BPMP, University of Montpellier, CNRS, INRAE, Institut Agro, Montpellier 34060, France
| | - Marisa S Otegui
- Department of Botany, University of Wisconsin-Madison, Madison, WI 53706, USA
- Center for Quantitative Cell Imaging, University of Wisconsin-Madison, Madison, WI 53706, USA
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Lavania D, Linh NM, Scarpella E. Of Cells, Strands, and Networks: Auxin and the Patterned Formation of the Vascular System. Cold Spring Harb Perspect Biol 2021; 13:cshperspect.a039958. [PMID: 33431582 DOI: 10.1101/cshperspect.a039958] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Throughout plant development, vascular cells continually form from within a population of seemingly equivalent cells. Vascular cells connect end to end to form continuous strands, and vascular strands connect at both or either end to form networks of exquisite complexity and mesmerizing beauty. Here we argue that experimental evidence gained over the past few decades implicates the plant hormone auxin-its production, transport, perception, and response-in all the steps that lead to the patterned formation of the plant vascular system, from the formation of vascular cells to their connection into vascular networks. We emphasize the organizing principles of the cell- and tissue-patterning process, rather than its molecular subtleties. In the picture that emerges, cells compete for an auxin-dependent, cell-polarizing signal; positive feedback between cell polarization and cell-to-cell movement of the polarizing signal leads to gradual selection of cell files; and selected cell files differentiate into vascular strands that drain the polarizing signal from the neighboring cells. Although the logic of the patterning process has become increasingly clear, the molecular details remain blurry; the future challenge will be to bring them into razor-sharp focus.
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Affiliation(s)
- Dhruv Lavania
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - Nguyen Manh Linh
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - Enrico Scarpella
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
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Ravichandran SJ, Linh NM, Scarpella E. The canalization hypothesis - challenges and alternatives. THE NEW PHYTOLOGIST 2020; 227:1051-1059. [PMID: 32285457 DOI: 10.1111/nph.16605] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Accepted: 04/01/2020] [Indexed: 05/14/2023]
Abstract
The 'canalization hypothesis' was suggested 50 years ago by Tsvi Sachs to account for the formation of vascular strands in response to wounding or auxin application. The hypothesis proposes that positive feedback between auxin movement through a cell and the cell's auxin conductivity leads to the gradual selection of narrow 'canals' of polar auxin transport that will differentiate into vascular strands. Though the hypothesis has provided an invaluable conceptual framework to understand the patterned formation of vascular strands, evidence has been accumulating that seems to be incompatible with the hypothesis. We suggest that the challenging evidence is incompatible with current interpretations of the hypothesis but not with the concept at the core of the hypothesis' original formulation.
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Affiliation(s)
- Sree Janani Ravichandran
- Department of Biological Sciences, University of Alberta, CW-405 Biological Sciences Building, Edmonton, AB, T6G 2E9, Canada
| | - Nguyen Manh Linh
- Department of Biological Sciences, University of Alberta, CW-405 Biological Sciences Building, Edmonton, AB, T6G 2E9, Canada
| | - Enrico Scarpella
- Department of Biological Sciences, University of Alberta, CW-405 Biological Sciences Building, Edmonton, AB, T6G 2E9, Canada
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12
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Govindaraju P, Verna C, Zhu T, Scarpella E. Vein patterning by tissue-specific auxin transport. Development 2020; 147:dev.187666. [PMID: 32493758 DOI: 10.1242/dev.187666] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 05/27/2020] [Indexed: 11/20/2022]
Abstract
Unlike in animals, in plants, vein patterning does not rely on direct cell-cell interaction and cell migration; instead, it depends on the transport of the plant hormone auxin, which in turn depends on the activity of the PIN-FORMED1 (PIN1) auxin transporter. The current hypotheses of vein patterning by auxin transport propose that, in the epidermis of the developing leaf, PIN1-mediated auxin transport converges to peaks of auxin level. From those convergence points of epidermal PIN1 polarity, auxin would be transported in the inner tissues where it would give rise to major veins. Here, we have tested predictions of this hypothesis and have found them unsupported: epidermal PIN1 expression is neither required nor sufficient for auxin transport-dependent vein patterning, whereas inner-tissue PIN1 expression turns out to be both required and sufficient for auxin transport-dependent vein patterning. Our results refute all vein patterning hypotheses based on auxin transport from the epidermis and suggest alternatives for future tests.
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Affiliation(s)
- Priyanka Govindaraju
- Department of Biological Sciences, University of Alberta, CW-405 Biological Sciences Building, Edmonton AB T6G 2E9, Canada
| | - Carla Verna
- Department of Biological Sciences, University of Alberta, CW-405 Biological Sciences Building, Edmonton AB T6G 2E9, Canada
| | - Tongbo Zhu
- Department of Biological Sciences, University of Alberta, CW-405 Biological Sciences Building, Edmonton AB T6G 2E9, Canada
| | - Enrico Scarpella
- Department of Biological Sciences, University of Alberta, CW-405 Biological Sciences Building, Edmonton AB T6G 2E9, Canada
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13
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Amalraj B, Govindaraju P, Krishna A, Lavania D, Linh NM, Ravichandran SJ, Scarpella E. GAL4
/
GFP enhancer‐trap
lines for identification and manipulation of cells and tissues in developing Arabidopsis leaves. Dev Dyn 2020; 249:1127-1146. [DOI: 10.1002/dvdy.181] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 03/30/2020] [Accepted: 04/11/2020] [Indexed: 12/12/2022] Open
Affiliation(s)
- Brindhi Amalraj
- Department of Biological SciencesUniversity of Alberta Edmonton Alberta Canada
| | | | - Anmol Krishna
- Department of Biological SciencesUniversity of Alberta Edmonton Alberta Canada
| | - Dhruv Lavania
- Department of Biological SciencesUniversity of Alberta Edmonton Alberta Canada
| | - Nguyen M. Linh
- Department of Biological SciencesUniversity of Alberta Edmonton Alberta Canada
| | | | - Enrico Scarpella
- Department of Biological SciencesUniversity of Alberta Edmonton Alberta Canada
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14
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Verna C, Ravichandran SJ, Sawchuk MG, Linh NM, Scarpella E. Coordination of tissue cell polarity by auxin transport and signaling. eLife 2019; 8:51061. [PMID: 31793881 PMCID: PMC6890459 DOI: 10.7554/elife.51061] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Accepted: 11/01/2019] [Indexed: 02/02/2023] Open
Abstract
Plants coordinate the polarity of hundreds of cells during vein formation, but how they do so is unclear. The prevailing hypothesis proposes that GNOM, a regulator of membrane trafficking, positions PIN-FORMED auxin transporters to the correct side of the plasma membrane; the resulting cell-to-cell, polar transport of auxin would coordinate tissue cell polarity and induce vein formation. Contrary to predictions of the hypothesis, we find that vein formation occurs in the absence of PIN-FORMED or any other intercellular auxin-transporter; that the residual auxin-transport-independent vein-patterning activity relies on auxin signaling; and that a GNOM-dependent signal acts upstream of both auxin transport and signaling to coordinate tissue cell polarity and induce vein formation. Our results reveal synergism between auxin transport and signaling, and their unsuspected control by GNOM in the coordination of tissue cell polarity during vein patterning, one of the most informative expressions of tissue cell polarization in plants. Plants, animals and other living things grow and develop over their lifetimes: for example, oak trees come from acorns and chickens begin their lives as eggs. To achieve these transformations, the cells in those living things must grow, divide and change their shape and other features. Plants and animals specify the directions in which their cells will grow and develop by gathering specific proteins to one side of the cells. This makes one side different from all the other sides, which the cells use as an internal compass that points in one direction. To align their internal compasses, animal cells touch one another and often move around inside the body. Plant cells, on the other hand, are surrounded by a wall that keeps them apart and prevents them from moving around. So how do plant cells align their internal compasses? Scientists have long thought that a protein called GNOM aligns the internal compasses of plant cells. The hypothesis proposes that GNOM gathers another protein, called PIN1, to one side of a cell. PIN1 would then pump a plant hormone known as auxin out of this first cell and, in doing so, would also drain auxin away from the cell on the opposite side. In this second cell, GNOM would then gather PIN1 to the side facing the first cell, and this process would repeat until all the cells' compasses were aligned. To test this hypothesis, Verna et al. combined microscopy with genetic approaches to study how cells' compasses are aligned in the leaves of a plant called Arabidopsis thaliana. The experiments revealed that auxin needs to move from cell-to-cell to align the cells’ compasses. However, contrary to the above hypothesis, this movement of auxin was not sufficient: the cells also needed to be able to detect and respond to the auxin that entered them. Along with controlling how auxin moved between the cells, GNOM also regulated how the cells responded to the auxin. These findings reveal how plants specify which directions their cells grow and develop. In the future, this knowledge may eventually aid efforts to improve crop yields by controlling the growth and development of crop plants.
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Affiliation(s)
- Carla Verna
- Department of Biological Sciences, University of Alberta, Edmonton, Canada
| | | | - Megan G Sawchuk
- Department of Biological Sciences, University of Alberta, Edmonton, Canada
| | - Nguyen Manh Linh
- Department of Biological Sciences, University of Alberta, Edmonton, Canada
| | - Enrico Scarpella
- Department of Biological Sciences, University of Alberta, Edmonton, Canada
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15
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Biedroń M, Banasiak A. Auxin-mediated regulation of vascular patterning in Arabidopsis thaliana leaves. PLANT CELL REPORTS 2018; 37:1215-1229. [PMID: 29992374 PMCID: PMC6096608 DOI: 10.1007/s00299-018-2319-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 07/04/2018] [Indexed: 05/02/2023]
Abstract
The vascular system develops in response to auxin flow as continuous strands of conducting tissues arranged in regular spatial patterns. However, a mechanism governing their regular and repetitive formation remains to be fully elucidated. A model system for studying the vascular pattern formation is the process of leaf vascularization in Arabidopsis. In this paper, we present current knowledge of important factors and their interactions in this process. Additionally, we propose the sequence of events leading to the emergence of continuous vascular strands and point to significant problems that need to be resolved in the future to gain a better understanding of the regulation of the vascular pattern development.
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Affiliation(s)
- Magdalena Biedroń
- Department of Plant Developmental Biology, Institute of Experimental Biology, University of Wrocław, ul. Kanonia 6/8, 50-328, Wrocław, Poland
| | - Alicja Banasiak
- Department of Plant Developmental Biology, Institute of Experimental Biology, University of Wrocław, ul. Kanonia 6/8, 50-328, Wrocław, Poland.
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16
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Shirakawa M, Hara-Nishimura I. Specialized Vacuoles of Myrosin Cells: Chemical Defense Strategy in Brassicales Plants. PLANT & CELL PHYSIOLOGY 2018; 59:1309-1316. [PMID: 29897512 DOI: 10.1093/pcp/pcy082] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 04/13/2018] [Indexed: 05/20/2023]
Abstract
Plant vacuoles display many versatile functions. Vacuoles in vegetative tissues are generally involved in protein degradation, and are called lytic vacuoles. However, vegetative vacuoles in specialized cells can accumulate large concentrations of proteins, such as those in idioblast myrosin cells along veins in the order Brassicales, which store large amounts of myrosinases (thioglucoside glucohydrolase and thioglucoside glucohydrolase). Myrosinases cleave the bond between sulfur and glucose in sulfur-rich compounds (glucosinolates) to produce toxic compounds (isothiocyanates) when plants are damaged by pests. This defense strategy is called the myrosinase-glucosinolate system. Recent studies identified atypical myrosinases, PENETRATION 2 (PEN2) and PYK10, along with key components for development of myrosin cells. In this review, we discuss three topics in the myrosinase-glucosinolate system. First, we summarize the complexity and importance of the myrosinase-glucosinolate system, including classical myrosinases, atypical myrosinases and the system that counteracts the myrosinase-glucosinolate system. Secondly, we describe molecular machineries underlying myrosin cell development, including specific reporters, cell lineage, cell differentiation and cell fate determination. The master regulators for myrosin cell differentiation, FAMA and SCREAM, are key transcription factors involved in guard cell differentiation. This indicates that myrosin cells and guard cells share similar transcriptional networks. Finally, we hypothesize that the myrosinase-glucosinolate system may have originated in stomata of ancestral Brassicales plants and, after that, plants co-opted this defense strategy into idioblasts near veins at inner tissue layers.
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Affiliation(s)
- Makoto Shirakawa
- Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Japan
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17
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Affiliation(s)
- Raili Ruonala
- Institute of Biotechnology and Department of Biosciences, University of Helsinki, 00014 Helsinki, Finland
- The Sainsbury Laboratory, University of Cambridge, Cambridge CB2 1LR, United Kingdom;, ,
| | - Donghwi Ko
- The Sainsbury Laboratory, University of Cambridge, Cambridge CB2 1LR, United Kingdom;, ,
| | - Ykä Helariutta
- Institute of Biotechnology and Department of Biosciences, University of Helsinki, 00014 Helsinki, Finland
- The Sainsbury Laboratory, University of Cambridge, Cambridge CB2 1LR, United Kingdom;, ,
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18
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Shirakawa M, Ueda H, Shimada T, Hara-Nishimura I. FAMA: A Molecular Link between Stomata and Myrosin Cells. TRENDS IN PLANT SCIENCE 2016; 21:861-871. [PMID: 27477926 DOI: 10.1016/j.tplants.2016.07.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 06/24/2016] [Accepted: 07/04/2016] [Indexed: 05/04/2023]
Abstract
Plants use sophisticated defense strategies against herbivores, including the myrosinase-glucosinolate system in Brassicales plants. This system sequesters myrosinase in myrosin cells, which are idioblasts in inner leaf tissues, and produces a toxic compound when cells are damaged by herbivores. Although the molecular mechanisms underlying myrosin cell development are largely unknown, recent studies have revealed that two key components, a basic helix-loop-helix (bHLH) transcription factor (FAMA) and vesicle trafficking factors (such as SYNTAXIN OF PLANTS 22), regulate the differentiation and fate determination of myrosin cells. FAMA also functions as a master regulator of guard cell (GC) differentiation. In this review, we discuss how FAMA operates two distinct genetic programs: the generation of myrosin cells in inner plant tissue and GCs in the epidermis.
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Affiliation(s)
- Makoto Shirakawa
- Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Haruko Ueda
- Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Tomoo Shimada
- Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
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19
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Bar-Sinai Y, Julien JD, Sharon E, Armon S, Nakayama N, Adda-Bedia M, Boudaoud A. Mechanical Stress Induces Remodeling of Vascular Networks in Growing Leaves. PLoS Comput Biol 2016; 12:e1004819. [PMID: 27074136 PMCID: PMC4830508 DOI: 10.1371/journal.pcbi.1004819] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 02/17/2016] [Indexed: 01/13/2023] Open
Abstract
Differentiation into well-defined patterns and tissue growth are recognized as key processes in organismal development. However, it is unclear whether patterns are passively, homogeneously dilated by growth or whether they remodel during tissue expansion. Leaf vascular networks are well-fitted to investigate this issue, since leaves are approximately two-dimensional and grow manyfold in size. Here we study experimentally and computationally how vein patterns affect growth. We first model the growing vasculature as a network of viscoelastic rods and consider its response to external mechanical stress. We use the so-called texture tensor to quantify the local network geometry and reveal that growth is heterogeneous, resembling non-affine deformations in composite materials. We then apply mechanical forces to growing leaves after veins have differentiated, which respond by anisotropic growth and reorientation of the network in the direction of external stress. External mechanical stress appears to make growth more homogeneous, in contrast with the model with viscoelastic rods. However, we reconcile the model with experimental data by incorporating randomness in rod thickness and a threshold in the rod growth law, making the rods viscoelastoplastic. Altogether, we show that the higher stiffness of veins leads to their reorientation along external forces, along with a reduction in growth heterogeneity. This process may lead to the reinforcement of leaves against mechanical stress. More generally, our work contributes to a framework whereby growth and patterns are coordinated through the differences in mechanical properties between cell types.
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Affiliation(s)
- Yohai Bar-Sinai
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot, Israel
- Racah Institute of Physics, The Hebrew University, Jerusalem, Israel
- Laboratoire de Physique Statistique, Ecole Normale Supérieure, CNRS, Université Paris VI, Université Paris VII, Paris, France
| | - Jean-Daniel Julien
- Laboratoire de Physique, ENS Lyon, CNRS, UCB Lyon I, Université de Lyon, Lyon, France
- Laboratoire Reproduction et Développement des Plantes, Univ Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, Lyon, France
- Laboratoire Joliot-Curie, Univ Lyon, ENS de Lyon, CNRS, Lyon, France
| | - Eran Sharon
- Racah Institute of Physics, The Hebrew University, Jerusalem, Israel
| | - Shahaf Armon
- Racah Institute of Physics, The Hebrew University, Jerusalem, Israel
| | - Naomi Nakayama
- Institute of Molecular Plant Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Mokhtar Adda-Bedia
- Laboratoire de Physique Statistique, Ecole Normale Supérieure, CNRS, Université Paris VI, Université Paris VII, Paris, France
| | - Arezki Boudaoud
- Laboratoire Reproduction et Développement des Plantes, Univ Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, Lyon, France
- Laboratoire Joliot-Curie, Univ Lyon, ENS de Lyon, CNRS, Lyon, France
- Institut Universitaire de France, Paris, France
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20
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Shirakawa M, Ueda H, Shimada T, Hara-Nishimura I. Myrosin cells are differentiated directly from ground meristem cells and are developmentally independent of the vasculature in Arabidopsis leaves. PLANT SIGNALING & BEHAVIOR 2016; 11:e1150403. [PMID: 26967973 PMCID: PMC4883950 DOI: 10.1080/15592324.2016.1150403] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Myrosin cells accumulate myrosinases in their vacuoles to catalyze the production of toxic compounds when tissues are damaged by herbivores. Myrosin cells are positioned adjacent to the abaxial side of the vasculature but their origin is unclear. To determine whether the myrosin cells are differentiated from vascular precursor cells, we generated a transgenic Arabidopsis line that expressed a myrosin cell reporter together with one of 3 vascular precursor cell reporters. The myrosin-positive cells were discontinuously distributed while the vascular precursor-positive cells were continuously distributed. The fluorescent signals of the myosin and vascular reporters did not overlap. Furthermore, the shape of myrosin-positive cells was different from the shape of vascular precursor-positive cells. These results indicate that myosin cells develop independently of the vasculature.
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Affiliation(s)
- Makoto Shirakawa
- Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Haruko Ueda
- Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Tomoo Shimada
- Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
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21
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Verna C, Sawchuk MG, Linh NM, Scarpella E. Control of vein network topology by auxin transport. BMC Biol 2015; 13:94. [PMID: 26560462 PMCID: PMC4641347 DOI: 10.1186/s12915-015-0208-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 10/28/2015] [Indexed: 02/08/2023] Open
Abstract
Background Tissue networks such as the vascular networks of plant and animal organs transport signals and nutrients in most multicellular organisms. The transport function of tissue networks depends on topological features such as the number of networks’ components and the components’ connectedness; yet what controls tissue network topology is largely unknown, partly because of the difficulties in quantifying the effects of genes on tissue network topology. We address this problem for the vein networks of plant leaves by introducing biologically motivated descriptors of vein network topology; we combine these descriptors with cellular imaging and molecular genetic analysis; and we apply this combination of approaches to leaves of Arabidopsis thaliana that lack function of, overexpress or misexpress combinations of four PIN-FORMED (PIN) genes—PIN1, PIN5, PIN6, and PIN8—which encode transporters of the plant signal auxin and are known to control vein network geometry. Results We find that PIN1 inhibits vein formation and connection, and that PIN6 acts redundantly to PIN1 in these processes; however, the functions of PIN6 in vein formation are nonhomologous to those of PIN1, while the functions of PIN6 in vein connection are homologous to those of PIN1. We further find that PIN8 provides functions redundant and homologous to those of PIN6 in PIN1-dependent inhibition of vein formation, but that PIN8 has no functions in PIN1/PIN6-dependent inhibition of vein connection. Finally, we find that PIN5 promotes vein formation; that all the vein-formation-promoting functions of PIN5 are redundantly inhibited by PIN6 and PIN8; and that these functions of PIN5, PIN6, and PIN8 are independent of PIN1. Conclusions Our results suggest that PIN-mediated auxin transport controls the formation of veins and their connection into networks. Electronic supplementary material The online version of this article (doi:10.1186/s12915-015-0208-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Carla Verna
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
| | - Megan G Sawchuk
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
| | - Nguyen Manh Linh
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
| | - Enrico Scarpella
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
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22
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Vanhaeren H, Gonzalez N, Inzé D. A Journey Through a Leaf: Phenomics Analysis of Leaf Growth in Arabidopsis thaliana. THE ARABIDOPSIS BOOK 2015; 13:e0181. [PMID: 26217168 PMCID: PMC4513694 DOI: 10.1199/tab.0181] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
In Arabidopsis, leaves contribute to the largest part of the aboveground biomass. In these organs, light is captured and converted into chemical energy, which plants use to grow and complete their life cycle. Leaves emerge as a small pool of cells at the vegetative shoot apical meristem and develop into planar, complex organs through different interconnected cellular events. Over the last decade, numerous phenotyping techniques have been developed to visualize and quantify leaf size and growth, leading to the identification of numerous genes that contribute to the final size of leaves. In this review, we will start at the Arabidopsis rosette level and gradually zoom in from a macroscopic view on leaf growth to a microscopic and molecular view. Along this journey, we describe different techniques that have been key to identify important events during leaf development and discuss approaches that will further help unraveling the complex cellular and molecular mechanisms that underlie leaf growth.
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Affiliation(s)
- Hannes Vanhaeren
- Department of Plant Systems Biology, VIB, B-9052 Gent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Gent, Belgium
| | - Nathalie Gonzalez
- Department of Plant Systems Biology, VIB, B-9052 Gent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Gent, Belgium
| | - Dirk Inzé
- Department of Plant Systems Biology, VIB, B-9052 Gent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Gent, Belgium
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23
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Fouracre JP, Ando S, Langdale JA. Cracking the Kranz enigma with systems biology. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:3327-39. [PMID: 24510938 DOI: 10.1093/jxb/eru015] [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] [Indexed: 05/09/2023]
Abstract
Leaves with Kranz anatomy exhibit a highly characteristic arrangement of closely spaced veins surrounded by concentric wreaths of bundle sheath and mesophyll cells. This anatomical framework is vital for effective C4 photosynthesis in nearly all known land plant lineages and has evolved independently on over 60 occasions. Over the last 3 years, technological advances, particularly in high-throughput DNA sequencing, have allowed the development of Kranz anatomy to be interrogated at unprecedented depth. This review highlights the recent advances in our understanding that have been facilitated by systems biology approaches, and proposes a testable model for the regulation of Kranz development.
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Affiliation(s)
- Jim P Fouracre
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford, OX1 3RB, UK
| | - Sayuri Ando
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford, OX1 3RB, UK
| | - Jane A Langdale
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford, OX1 3RB, UK
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24
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Furuta KM, Hellmann E, Helariutta Y. Molecular control of cell specification and cell differentiation during procambial development. ANNUAL REVIEW OF PLANT BIOLOGY 2014; 65:607-38. [PMID: 24579995 DOI: 10.1146/annurev-arplant-050213-040306] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Land plants develop vascular tissues that enable the long-distance transport of water and nutrients in xylem and phloem, provide mechanical support for their vertical growth, and produce cells in radial growth. Vascular tissues are produced in many parts of the plant and during different developmental stages. Early vascular development is focused in procambial meristems, and in some species it continues during the secondary phase of plant development in cambial meristems. In this review, we highlight recent progress in understanding procambial development. This involves the analysis of stem cell-like properties of procambial tissues, specification of xylem and phloem, and differentiation of the conductive tissues. Several major plant hormones, small-RNA species, and transcriptional networks play a role in vascular development. We describe current approaches to integrating these networks as well as their potential role in explaining the diversity and evolution of plant vascular systems.
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Affiliation(s)
- Kaori Miyashima Furuta
- Institute of Biotechnology and Department of Biology and Environmental Sciences, University of Helsinki, Helsinki FIN-00014, Finland; , ,
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25
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Marcos D, Berleth T. Dynamic auxin transport patterns preceding vein formation revealed by live-imaging of Arabidopsis leaf primordia. FRONTIERS IN PLANT SCIENCE 2014; 5:235. [PMID: 24966861 PMCID: PMC4052221 DOI: 10.3389/fpls.2014.00235] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2014] [Accepted: 05/11/2014] [Indexed: 05/18/2023]
Abstract
Self-regulatory patterning mechanisms capable of generating biologically meaningful, yet unpredictable cellular patterns offer unique opportunities for obtaining mathematical descriptions of underlying patterning systems properties. The networks of higher-order veins in leaf primordia constitute such a self-regulatory system. During the formation of higher-order veins, vascular precursors are selected from a homogenous field of subepidermal cells in unpredictable positions to eventually connect in complex cellular networks. Auxin transport routes have been implicated in this selection process, but understanding of their role in vascular patterning has been limited by our inability to monitor early auxin transport dynamics in vivo. Here we describe a live-imaging system in emerging Arabidopsis thaliana leaves that uses a PIN1:GFP reporter to visualize auxin transport routes and an Athb8:YFP reporter as a marker for vascular commitment. Live-imaging revealed common features initiating the formation of all higher-order veins. The formation of broad PIN1 expression domains is followed by their restriction, leading to sustained, elevated PIN1 expression in incipient procambial cells files, which then express Athb8. Higher-order PIN1 expression domains (hPEDs) are initiated as freely ending domains that extend toward each other and sometimes fuse with them, creating connected domains. During the restriction and specification phase, cells in wider hPEDs are partitioned into vascular and non-vascular fates: Central cells acquire a coordinated cell axis and express elevated PIN1 levels as well as the pre-procambial marker Athb8, while edge cells downregulate PIN1 and remain isodiametric. The dynamic nature of the early selection process is underscored by the instability of early hPEDs, which can result in dramatic changes in vascular network architecture prior to Athb8 expression, which is correlated with the promotion onto vascular cell fate.
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Affiliation(s)
| | - Thomas Berleth
- *Correspondence: Thomas Berleth, Department of Cell and Systems Biology, University of Toronto, 25 Willcocks Street, Toronto, ON M5S 3B2, Canada e-mail:
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26
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Jacques E, Verbelen JP, Vissenberg K. Mechanical stress in Arabidopsis leaves orients microtubules in a 'continuous' supracellular pattern. BMC PLANT BIOLOGY 2013; 13:163. [PMID: 24138025 PMCID: PMC3853881 DOI: 10.1186/1471-2229-13-163] [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: 11/29/2012] [Accepted: 10/09/2013] [Indexed: 05/02/2023]
Abstract
BACKGROUND Cortical microtubules form a dynamic network and continuously undergo shrinking (catastrophe), pausing and rebuilding (rescue). The advantage of such a dynamic system is that it may mediate appropriate responses in a short time span. Microtubules are known to play a pivotal role in determining the orientation of the cellulose microfibril deposition in the plant cell wall. The latter is a solid exoskeleton surrounding the protoplast. It forms the physical framework that interconnects most cells and has to bear the tensile stresses within the tissue. Here we describe the effect of externally applied pressure on microtubule organization in growing Arabidopsis leaves. RESULTS Confocal microscopy examination of transgenic plants bearing GFP-tagged TUA6 proteins led to the observation that application of an additional mechanical pressure on growing Arabidopsis leaves triggers an excessive bundling of microtubules within the individual cell. Besides, the microtubules seem to align in neighboring cells, creating a 'continuous' supracellular pattern. This effect occurs within 3 hours after applied external force and is age-dependent, whereby only cells of leaves up to 19 days after sowing (DAS) are susceptible to the applied pressure. CONCLUSIONS Upon externally applied pressure on developing Arabidopsis leaves, microtubules bundle and rearrange to form seemingly continuous supracellular patterns. As microtubules guide the cellulose synthase complexes, this observed reorganisation pattern probably affects the cellulose deposition, contributing to the reinforcement of the cell wall in a particular position to cope with the extra-applied pressure. The age-effect is reasonable, since younger cells, which are actively shaping their cell walls, are more vulnerable to altered mechanical stresses while in leaves older than 19 DAS, the walls are more robust and therefore can sustain the applied forces.
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Affiliation(s)
- Eveline Jacques
- Department Biology, Plant Growth and Development, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerpen, Belgium
| | - Jean-Pierre Verbelen
- Department Biology, Plant Growth and Development, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerpen, Belgium
| | - Kris Vissenberg
- Department Biology, Plant Growth and Development, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerpen, Belgium
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27
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Sawchuk MG, Scarpella E. Polarity, continuity, and alignment in plant vascular strands. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2013; 55:824-834. [PMID: 23773763 DOI: 10.1111/jipb.12086] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Accepted: 06/04/2013] [Indexed: 06/02/2023]
Abstract
Plant vascular cells are joined end to end along uninterrupted lines to connect shoot organs with roots; vascular strands are thus polar, continuous, and internally aligned. What controls the formation of vascular strands with these properties? The "auxin canalization hypothesis"-based on positive feedback between auxin flow through a cell and the cell's capacity for auxin transport-predicts the selection of continuous files of cells that transport auxin polarly, thus accounting for the polarity and continuity of vascular strands. By contrast, polar, continuous auxin transport-though required-is insufficient to promote internal alignment of vascular strands, implicating additional factors. The auxin canalization hypothesis was derived from the response of mature tissue to auxin application but is consistent with molecular and cellular events in embryo axis formation and shoot organ development. Objections to the hypothesis have been raised based on vascular organizations in callus tissue and shoot organs but seem unsupported by available evidence. Other objections call instead for further research; yet the inductive and orienting influence of auxin on continuous vascular differentiation remains unique.
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Affiliation(s)
- Megan G Sawchuk
- Department of Biological Sciences, University of Alberta, Edmonton Alberta, Canada, T6G 2E9
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28
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Sack L, Scoffoni C. Leaf venation: structure, function, development, evolution, ecology and applications in the past, present and future. THE NEW PHYTOLOGIST 2013; 198:983-1000. [PMID: 23600478 DOI: 10.1111/nph.12253] [Citation(s) in RCA: 323] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2012] [Accepted: 02/18/2013] [Indexed: 05/18/2023]
Abstract
The design and function of leaf venation are important to plant performance, with key implications for the distribution and productivity of ecosystems, and applications in paleobiology, agriculture and technology. We synthesize classical concepts and the recent literature on a wide range of aspects of leaf venation. We describe 10 major structural features that contribute to multiple key functions, and scale up to leaf and plant performance. We describe the development and plasticity of leaf venation and its adaptation across environments globally, and a new global data compilation indicating trends relating vein length per unit area to climate, growth form and habitat worldwide. We synthesize the evolution of vein traits in the major plant lineages throughout paleohistory, highlighting the multiple origins of individual traits. We summarize the strikingly diverse current applications of leaf vein research in multiple fields of science and industry. A unified core understanding will enable an increasing range of plant biologists to incorporate leaf venation into their research.
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Affiliation(s)
- Lawren Sack
- Department of Ecology and Evolution, University of California Los Angeles, 621 Charles E. Young Drive South, Los Angeles, CA, 90095, USA
| | - Christine Scoffoni
- Department of Ecology and Evolution, University of California Los Angeles, 621 Charles E. Young Drive South, Los Angeles, CA, 90095, USA
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Lucas WJ, Groover A, Lichtenberger R, Furuta K, Yadav SR, Helariutta Y, He XQ, Fukuda H, Kang J, Brady SM, Patrick JW, Sperry J, Yoshida A, López-Millán AF, Grusak MA, Kachroo P. The plant vascular system: evolution, development and functions. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2013; 55:294-388. [PMID: 23462277 DOI: 10.1111/jipb.12041] [Citation(s) in RCA: 398] [Impact Index Per Article: 36.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The emergence of the tracheophyte-based vascular system of land plants had major impacts on the evolution of terrestrial biology, in general, through its role in facilitating the development of plants with increased stature, photosynthetic output, and ability to colonize a greatly expanded range of environmental habitats. Recently, considerable progress has been made in terms of our understanding of the developmental and physiological programs involved in the formation and function of the plant vascular system. In this review, we first examine the evolutionary events that gave rise to the tracheophytes, followed by analysis of the genetic and hormonal networks that cooperate to orchestrate vascular development in the gymnosperms and angiosperms. The two essential functions performed by the vascular system, namely the delivery of resources (water, essential mineral nutrients, sugars and amino acids) to the various plant organs and provision of mechanical support are next discussed. Here, we focus on critical questions relating to structural and physiological properties controlling the delivery of material through the xylem and phloem. Recent discoveries into the role of the vascular system as an effective long-distance communication system are next assessed in terms of the coordination of developmental, physiological and defense-related processes, at the whole-plant level. A concerted effort has been made to integrate all these new findings into a comprehensive picture of the state-of-the-art in the area of plant vascular biology. Finally, areas important for future research are highlighted in terms of their likely contribution both to basic knowledge and applications to primary industry.
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Affiliation(s)
- William J Lucas
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA 95616, USA.
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30
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Rubio-Somoza I, Weigel D. Coordination of flower maturation by a regulatory circuit of three microRNAs. PLoS Genet 2013; 9:e1003374. [PMID: 23555288 PMCID: PMC3610633 DOI: 10.1371/journal.pgen.1003374] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Accepted: 01/29/2013] [Indexed: 12/27/2022] Open
Abstract
The development of multicellular organisms relies on interconnected genetic programs that control progression through their life cycle. MicroRNAs (miRNAs) and transcription factors (TFs) play key roles in such regulatory circuits. Here, we describe how three evolutionary conserved miRNA-TF pairs interact to form multiple checkpoints during reproductive development of Arabidopsis thaliana. Genetic, cellular, and physiological experiments show that miR159- and miR319-regulated MYB and TCP transcription factors pattern the expression of miR167 family members and their ARF6/8 targets. Coordinated action of these miRNA-TF pairs is crucial for the execution of consecutive hormone-dependent transitions during flower maturation. Cross-regulation includes both cis- and trans-regulatory interactions between these miRNAs and their targets. Our observations reveal how different miRNA-TF pairs can be organized into modules that coordinate successive steps in the plant life cycle. Development of multicellular organisms relies on properly timed execution of different genetic programs. An example is provided by developmental progression of flowers, which begins with the initiation of individual organs, followed by differentiation, growth, and finally production of the gametes. This article investigates the contribution of three microRNAs (miRNAs) and the transcription factors (TFs) that are regulated by these miRNAs to this process. Two of the miRNA-TF pairs act early to control in parallel the activity of the third miRNA-TF pair, which in turn modulates hormone programs that drive organ maturation and reproduction. Importantly, the two upstream TFs directly interact to regulate expression of the downstream miRNA. The results described here demonstrate how miRNA-TF pairs can be organized into regulatory circuits, with independent miRNA-TF pairs converging on common downstream genes.
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Affiliation(s)
- Ignacio Rubio-Somoza
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, Tübingen, Germany.
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31
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Shaw SL, Ehrhardt DW. Smaller, faster, brighter: advances in optical imaging of living plant cells. ANNUAL REVIEW OF PLANT BIOLOGY 2013; 64:351-75. [PMID: 23506334 DOI: 10.1146/annurev-arplant-042110-103843] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The advent of fluorescent proteins and access to modern imaging technologies have dramatically accelerated the pace of discovery in plant cell biology. Remarkable new insights into such diverse areas as plant pathogenesis, cytoskeletal dynamics, sugar transport, cell wall synthesis, secretory control, and hormone signaling have come from careful examination of living cells using advanced optical probes. New technologies, both commercially available and on the horizon, promise a continued march toward more quantitative methods for imaging and for extending the optical exploration of biological structure and activity to molecular scales. In this review, we lay out fundamental issues in imaging plant specimens and look ahead to several technological innovations in molecular tools, instrumentation, imaging methods, and specimen handling that show promise for shaping the coming era of plant cell biology.
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Affiliation(s)
- Sidney L Shaw
- Department of Biology, Indiana University, Bloomington, IN 47405, USA.
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32
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Wenzel CL, Marrison J, Mattsson J, Haseloff J, Bougourd SM. Ectopic divisions in vascular and ground tissues of Arabidopsis thaliana result in distinct leaf venation defects. JOURNAL OF EXPERIMENTAL BOTANY 2012; 63:5351-64. [PMID: 22936832 PMCID: PMC3431004 DOI: 10.1093/jxb/ers196] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Leaf venation patterns vary considerably between species and between leaves within a species. A mechanism based on canalization of auxin transport has been suggested as the means by which plastic yet organized venation patterns are generated. This study assessed the plasticity of Arabidopsis thaliana leaf venation in response to ectopic ground or procambial cell divisions and auxin transport inhibition (ATI). Ectopic ground cell divisions resulted in vascular fragments between major veins, whereas ectopic procambial cell divisions resulted in additional, abnormal vessels along major veins, with more severely perturbed lines forming incomplete secondary and higher-order venation. These responses imply limited vascular plasticity in response to unscheduled cell divisions. Surprisingly, a combination of ectopic ground cell divisions and ATI resulted in massive vascular overgrowth. It is hypothesized that the vascular overproduction in auxin transport-inhibited wild-type leaves is limited by simultaneous differentiation of ground cells into mesophyll cells. Ectopic ground cell divisions may negate this effect by providing undifferentiated ground cells that respond to accumulated auxin by differentiation into vascular cells.
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Affiliation(s)
- C L Wenzel
- Department of Biology, University of York, York, Y010 5DD, UK.
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33
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Donner TJ, Scarpella E. Transcriptional control of early vein expression of CYCA2; 1 and CYCA2;4 in Arabidopsis leaves. Mech Dev 2012; 130:14-24. [PMID: 22842098 DOI: 10.1016/j.mod.2012.07.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 06/14/2012] [Accepted: 07/16/2012] [Indexed: 01/14/2023]
Abstract
Unlike most animal tissue networks, the patterns of vein networks in plant leaves are variable and plastic, suggesting distinct control mechanisms. Thus, knowledge of the gene regulatory circuits that pattern leaf vein networks could suggest new control mechanisms of tissue network formation. However, the cis-regulatory elements required for expression at early stages of vein development are largely unknown. Here we show that the Arabidopsis genes CYCLIN A2;1 (CYCA2;1) and CYCLIN A2;4 (CYCA2;4), previously shown to act redundantly in vein cell proliferation, are expressed at early stages of vein development. We show that stage-specific expression of CYCA2;1 and CYCA2;4 in vein development depends on regulatory elements containing, respectively, one and three evolutionarily conserved transcription-factor binding sites. Our data suggest that early vein expression is encoded in regulatory elements of different structures.
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Affiliation(s)
- Tyler J Donner
- Department of Biological Sciences, University of Alberta, CW-405 Biological Sciences Building, Edmonton, AB, Canada T6G 2E9
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34
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Wozny M, Schattat MH, Mathur N, Barton K, Mathur J. Color recovery after photoconversion of H2B::mEosFP allows detection of increased nuclear DNA content in developing plant cells. PLANT PHYSIOLOGY 2012; 158:95-106. [PMID: 22108524 PMCID: PMC3252088 DOI: 10.1104/pp.111.187062] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Accepted: 11/21/2011] [Indexed: 05/10/2023]
Abstract
Many higher plants are polysomatic whereby different cells possess variable amounts of nuclear DNA. The conditional triggering of endocycles results in higher nuclear DNA content (C value) that in some cases has been correlated to increased cell size. While numerous multicolored fluorescent protein (FP) probes have revealed the general behavior of the nucleus and intranuclear components, direct visualization and estimation of changes in nuclear-DNA content in live cells during their development has not been possible. Recently, monomeric Eos fluorescent protein (mEosFP) has emerged as a useful photoconvertible protein whose color changes irreversibly from a green to a red fluorescent form upon exposure to violet-blue light. The stability and irreversibility of red fluorescent mEosFP suggests that detection of green color recovery would be possible as fresh mEosFP is produced after photoconversion. Thus a ratiometric evaluation of the red and green forms of mEosFP following photoconversion could be used to estimate production of a core histone such as H2B during its concomitant synthesis with DNA in the synthesis phase of the cell cycle. Here we present proof of concept observations on transgenic tobacco (Nicotiana tabacum) Bright Yellow 2 cells and Arabidopsis (Arabidopsis thaliana) plants stably expressing H2B::mEosFP. In Arabidopsis seedlings an increase in green fluorescence is observed specifically in cells known to undergo endoreduplication. The detection of changes in nuclear DNA content by correlating color recovery of H2B::mEosFP after photoconversion is a novel approach involving a single FP. The method has potential for facilitating detailed investigations on conditions that favor increased cell size and the development of polysomaty in plants.
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Affiliation(s)
| | | | | | | | - Jaideep Mathur
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G2W1
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35
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Ckurshumova W, Caragea AE, Goldstein RS, Berleth T. Glow in the dark: fluorescent proteins as cell and tissue-specific markers in plants. MOLECULAR PLANT 2011; 4:794-804. [PMID: 21772029 DOI: 10.1093/mp/ssr059] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Since the hallmark discovery of Aequorea victoria's Green Fluorescent Protein (GFP) and its adaptation for efficient use in plants, fluorescent protein tags marking expression profiles or genuine proteins of interest have been used to recognize plant tissues and cell types, to monitor dynamic cell fate selection processes, and to obtain cell type-specific transcriptomes. Fluorescent tagging enabled visualization in living tissues and the precise recordings of dynamic expression pattern changes. The resulting accurate recording of cell fate acquisition kinetics in space and time has strongly stimulated mathematical modeling of self-organizing feedback mechanisms. In developmental studies, the use of fluorescent proteins has become critical, where morphological markers of tissues, cell types, or differentiation stages are either not known or not easily recognizable. In this review, we focus on the use of fluorescent markers to identify and illuminate otherwise invisible cell states in plant development.
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Affiliation(s)
- Wenzislava Ckurshumova
- Department of Cell and Systems Biology, University of Toronto, 25 Willcocks St, Toronto, ON M5S 3B2, Canada.
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36
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Vanneste S, Coppens F, Lee E, Donner TJ, Xie Z, Van Isterdael G, Dhondt S, De Winter F, De Rybel B, Vuylsteke M, De Veylder L, Friml J, Inzé D, Grotewold E, Scarpella E, Sack F, Beemster GTS, Beeckman T. Developmental regulation of CYCA2s contributes to tissue-specific proliferation in Arabidopsis. EMBO J 2011; 30:3430-41. [PMID: 21772250 DOI: 10.1038/emboj.2011.240] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Accepted: 06/24/2011] [Indexed: 11/09/2022] Open
Abstract
In multicellular organisms, morphogenesis relies on a strict coordination in time and space of cell proliferation and differentiation. In contrast to animals, plant development displays continuous organ formation and adaptive growth responses during their lifespan relying on a tight coordination of cell proliferation. How developmental signals interact with the plant cell-cycle machinery is largely unknown. Here, we characterize plant A2-type cyclins, a small gene family of mitotic cyclins, and show how they contribute to the fine-tuning of local proliferation during plant development. Moreover, the timely repression of CYCA2;3 expression in newly formed guard cells is shown to require the stomatal transcription factors FOUR LIPS/MYB124 and MYB88, providing a direct link between developmental programming and cell-cycle exit in plants. Thus, transcriptional downregulation of CYCA2s represents a critical mechanism to coordinate proliferation during plant development.
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37
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Peer WA, Blakeslee JJ, Yang H, Murphy AS. Seven things we think we know about auxin transport. MOLECULAR PLANT 2011; 4:487-504. [PMID: 21505044 DOI: 10.1093/mp/ssr034] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Polar transport of the phytohormone auxin and the establishment of localized auxin maxima regulate embryonic development, stem cell maintenance, root and shoot architecture, and tropic growth responses. The past decade has been marked by dramatic progress in efforts to elucidate the complex mechanisms by which auxin transport regulates plant growth. As the understanding of auxin transport regulation has been increasingly elaborated, it has become clear that this process is involved in almost all plant growth and environmental responses in some way. However, we still lack information about some basic aspects of this fundamental regulatory mechanism. In this review, we present what we know (or what we think we know) and what we do not know about seven auxin-regulated processes. We discuss the role of auxin transport in gravitropism in primary and lateral roots, phototropism, shoot branching, leaf expansion, and venation. We also discuss the auxin reflux/fountain model at the root tip, flavonoid modulation of auxin transport processes, and outstanding aspects of post-translational regulation of auxin transporters. This discussion is not meant to be exhaustive, but highlights areas in which generally held assumptions require more substantive validation.
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Affiliation(s)
- Wendy Ann Peer
- Department of Horticulture, 625 Agriculture Mall Drive, Purdue University, West Lafayette, IN 47907, USA.
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38
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Gardiner J, Donner TJ, Scarpella E. Simultaneous activation of SHR and ATHB8 expression defines switch to preprocambial cell state in Arabidopsis leaf development. Dev Dyn 2010; 240:261-70. [DOI: 10.1002/dvdy.22516] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
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39
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Matte Risopatron JP, Sun Y, Jones BJ. The vascular cambium: molecular control of cellular structure. PROTOPLASMA 2010; 247:145-161. [PMID: 20978810 DOI: 10.1007/s00709-010-0211-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Accepted: 09/09/2010] [Indexed: 05/30/2023]
Abstract
Indeterminate growth and the production of new organs in plants require a constant supply of new cells. The majority of these cells are produced in mitotic regions called meristems. For primary or tip growth of the roots and shoots, the meristems are located in the apices. These apical meristems have been shown to function as developmentally regulated and environmentally responsive stem cell niches. The principle requirements to maintain a functioning meristem in a dynamic system are a balance of cell division and differentiation and the regulation of the planes of cell division and expansion. Woody plants also have secondary indeterminate mitotic regions towards the exterior of roots, stems and branches that produce the cells for continued growth in girth. The chief secondary meristem is the vascular cambium (VC). As its name implies, cells produced in the VC contribute to the growth in girth via the production of secondary vascular elements. Although we know a considerable amount about the cellular and molecular basis of the apical meristems, our knowledge of the cellular basis and molecular functioning of the VC has been rudimentary. This is now changing as a growing body of research shows that the primary and secondary meristems share some common fundamental regulatory mechanisms. In this review, we outline recent research that is leading to a better understanding of the molecular forces that shape the cellular structure and function of the VC.
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40
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Alim K, Frey E. Quantitative predictions on auxin-induced polar distribution of PIN proteins during vein formation in leaves. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2010; 33:165-173. [PMID: 20571847 DOI: 10.1140/epje/i2010-10604-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Accepted: 05/10/2010] [Indexed: 05/29/2023]
Abstract
The dynamic patterning of the plant hormone auxin and its efflux facilitator the PIN protein are the key regulators for the spatial and temporal organization of plant development. In particular auxin induces the polar localization of its own efflux facilitator. Due to this positive feedback, auxin flow is directed and patterns of auxin and PIN arise. During the earliest stage of vein initiation in leaves auxin accumulates in a single cell in a rim of epidermal cells from which it flows into the ground meristem tissue of the leaf blade. There the localized auxin supply yields the successive polarization of PIN distribution along a strand of cells. We model the auxin and PIN dynamics within cells with a minimal canalization model. Solving the model analytically we uncover an excitable polarization front that triggers a polar distribution of PIN proteins in cells. As polarization fronts may extend to opposing directions from their initiation site, we suggest a possible resolution to the puzzling occurrence of bipolar cells, thus we offer an explanation for the development of closed, looped veins. Employing non-linear analysis, we identify the role of the contributing microscopic processes during polarization. Furthermore, we deduce quantitative predictions on polarization fronts establishing a route to determine the up to now largely unknown kinetic rates of auxin and PIN dynamics.
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Affiliation(s)
- K Alim
- Arnold Sommerfeld Center for Theoretical Physics and Center for NanoScience, Ludwig-Maximilians-Universität, Theresienstr. 37, D-80333, München, Germany.
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41
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Scarpella E, Barkoulas M, Tsiantis M. Control of leaf and vein development by auxin. Cold Spring Harb Perspect Biol 2010; 2:a001511. [PMID: 20182604 DOI: 10.1101/cshperspect.a001511] [Citation(s) in RCA: 162] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Leaves are the main photosynthetic organs of vascular plants and show considerable diversity in their geometries, ranging from simple spoon-like forms to complex shapes with individual leaflets, as in compound leaves. Leaf vascular tissues, which act as conduits of both nutrients and signaling information, are organized in networks of different architectures that usually mirror the surrounding leaf shape. Understanding the processes that endow leaves and vein networks with ordered and closely aligned shapes has captured the attention of biologists and mathematicians since antiquity. Recent work has suggested that the growth regulator auxin has a key role in both initiation and elaboration of final morphology of both leaves and vascular networks. A key feature of auxin action is the existence of feedback loops through which auxin regulates its own transport. These feedbacks may facilitate the iterative generation of basic modules that underlies morphogenesis of both leaves and vasculature.
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Affiliation(s)
- Enrico Scarpella
- Department of Biological Sciences, University of Alberta, Edmonton AB, Canada.
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42
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Ji J, Strable J, Shimizu R, Koenig D, Sinha N, Scanlon MJ. WOX4 promotes procambial development. PLANT PHYSIOLOGY 2010; 152:1346-56. [PMID: 20044450 PMCID: PMC2832261 DOI: 10.1104/pp.109.149641] [Citation(s) in RCA: 147] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2009] [Accepted: 12/21/2009] [Indexed: 05/20/2023]
Abstract
Plant shoot organs arise from initial cells that are recruited from meristematic tissues. Previous studies have shown that members of the WUSCHEL-related HOMEOBOX (WOX) gene family function to organize various initial cell populations during plant development. The function of the WOX4 gene is previously undescribed in any plant species. Comparative analyses of WOX4 transcription and function are presented in Arabidopsis (Arabidopsis thaliana), a simple-leafed plant with collateral vasculature, and in tomato (Solanum lycopersicum), a dissected-leafed species with bicollateral venation. WOX4 is transcribed in the developing vascular bundles of root and shoot lateral organs in both Arabidopsis and tomato. RNA interference-induced down-regulation of WOX4 in Arabidopsis generated small plants whose vascular bundles accumulated undifferentiated ground tissue and exhibited severe reductions in differentiated xylem and phloem. In situ hybridization analyses of Atwox4-RNA interference plants revealed delayed and reduced expression of both the phloem developmental marker ALTERED PHLOEM1 and HOMEOBOX GENE8, a marker of the vascular procambium. Overexpression of SlWOX4 correlated with overproliferation of xylem and phloem in transgenic tomato seedlings. The cumulative data suggest that the conserved WOX4 function is to promote differentiation and/or maintenance of the vascular procambium, the initial cells of the developing vasculature.
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Affiliation(s)
- Jiabing Ji
- Plant Biology Department, University of Georgia, Athens, Georgia 30602
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43
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44
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Donner TJ, Sherr I, Scarpella E. Auxin signal transduction in Arabidopsis vein formation. PLANT SIGNALING & BEHAVIOR 2010; 5:70-2. [PMID: 20592815 PMCID: PMC2835964 DOI: 10.4161/psb.5.1.10233] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Accepted: 10/01/2009] [Indexed: 05/12/2023]
Abstract
The plant signaling molecule auxin has been implicated in the control of a confounding multitude of diverse processes in plants, including leaf vascular patterning. In Arabidopsis leaves, expression of the HD-ZIP III gene ATHB8 is initiated in files of isodiametric subepidermal cells that will elongate into vein-forming procambium. We have recently shown that ATHB8 is transiently required for preprocambial development and procambium differentiation, and that permanence of the effects of loss of ATHB8 function on vein formation depends on the activity of the auxin response factor MONOPTEROS (MP). Further, we have shown that the onset of ATHB8 expression is directly and positively regulated by MP through an auxin-response element in the ATHB8 promoter, suggesting a molecular path by which auxin signals are translated into vein patterning inputs. Within broad fields of MP expression, however, only a subset of cells initiates expression of ATHB8. Here we discuss putative mechanisms by which wide domains of MP expression could activate ATHB8 transcription in single cell files.
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Affiliation(s)
- Tyler J Donner
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
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45
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McKown AD, Dengler NG. Shifts in leaf vein density through accelerated vein formation in C4 Flaveria (Asteraceae). ANNALS OF BOTANY 2009; 104:1085-98. [PMID: 19759038 PMCID: PMC2766201 DOI: 10.1093/aob/mcp210] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2009] [Revised: 06/19/2009] [Accepted: 07/22/2009] [Indexed: 05/21/2023]
Abstract
BACKGROUND AND AIMS Leaf venation in many C(4) species is characterized by high vein density, essential in facilitating rapid intercellular diffusion of C(4) photosynthetic metabolites between different tissues (mesophyll, bundle sheath). Greater vein density has been hypothesized to be an early step in C(4) photosynthesis evolution. Development of C(4) vein patterning is thought to occur from either accelerated or prolonged procambium formation, relative to ground tissue development. METHODS Cleared and sectioned tissues of phylogenetically basal C(3) Flaveria robusta and more derived C(4) Flaveria bidentis were compared for vein pattern in mature leaves and vein pattern formation in developing leaves. KEY RESULTS In mature leaves, major vein density did not differ between C(3) and C(4) Flaveria species, whereas minor veins were denser in C(4) species than in C(3) species. The developmental study showed that both major and minor vein patterning in leaves of C(3) and C(4) species were initiated at comparable stages (based on leaf length). An additional vein order in the C(4) species was observed during initiation of the higher order minor veins compared with the C(3) species. In the two species, expansion of bundle sheath and mesophyll cells occurred after vein pattern was complete and xylem differentiation was continuous in minor veins. In addition, mesophyll cells ceased dividing sooner and enlarged less in C(4) species than in C(3) species. CONCLUSIONS Leaf vein pattern characteristic to C(4) Flaveria was achieved primarily through accelerated and earlier offset of higher order vein formation, rather than other modifications in the timing of vein pattern formation, as compared with C(3) species. Earlier cessation of mesophyll cell division and reduced expansion also contributed to greater vein density in the C(4) species. The relatively late expansion of bundle sheath and mesophyll cells shows that vein patterning precedes ground tissue development in C(4) species.
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Affiliation(s)
- Athena D McKown
- Department of Forest Sciences, University of British Columbia, 2424 Main Mall, Vancouver, BC V6T 1Z4, Canada.
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46
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Donner TJ, Sherr I, Scarpella E. Regulation of preprocambial cell state acquisition by auxin signaling in Arabidopsis leaves. Development 2009; 136:3235-46. [DOI: 10.1242/dev.037028] [Citation(s) in RCA: 218] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The principles underlying the formation of veins in the leaf have long intrigued developmental biologists. In Arabidopsis leaves, files of anatomically inconspicuous subepidermal cells that will elongate into vein-forming procambial cells selectively activate ATHB8 gene expression. The biological role of ATHB8 in vein formation and the molecular events that culminate in acquisition of the ATHB8preprocambial cell state are unknown, but intertwined pathways of auxin transport and signal transduction have been implicated in defining paths of vascular strand differentiation. Here we show that ATHB8 is required to stabilize preprocambial cell specification against auxin transport perturbations, to restrict preprocambial cell state acquisition to narrow fields and to coordinate procambium formation within and between veins. We further show that ATHB8 expression at preprocambial stages is directly and positively controlled by the auxin-response transcription factor MONOPTEROS (MP) through an auxin-response element in the ATHB8promoter. We finally show that the consequences of loss of ATHB8function for vein formation are masked by MP activity. Our observations define, at the molecular level, patterning inputs of auxin signaling in vein formation.
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Affiliation(s)
- Tyler J. Donner
- Department of Biological Sciences, University of Alberta, CW-405 Biological Sciences Building, Edmonton AB, T6G 2E9, Canada
| | - Ira Sherr
- Department of Biological Sciences, University of Alberta, CW-405 Biological Sciences Building, Edmonton AB, T6G 2E9, Canada
| | - Enrico Scarpella
- Department of Biological Sciences, University of Alberta, CW-405 Biological Sciences Building, Edmonton AB, T6G 2E9, Canada
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47
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Corson F, Adda-Bedia M, Boudaoud A. In silico leaf venation networks: growth and reorganization driven by mechanical forces. J Theor Biol 2009; 259:440-8. [PMID: 19446571 DOI: 10.1016/j.jtbi.2009.05.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2008] [Revised: 05/05/2009] [Accepted: 05/05/2009] [Indexed: 11/25/2022]
Abstract
Development commonly involves an interplay between signaling, genetic expression and biophysical forces. However, the relative importance of these mechanisms during the different stages of development is unclear. Leaf venation networks provide a fitting context for the examination of these questions. In mature leaves, venation patterns are extremely diverse, yet their local structure satisfies a universal property: at junctions between veins, angles and diameters are related by a vectorial equation analogous to a force balance. Using a cell proliferation model, we reproduce in silico the salient features of venation patterns. Provided that vein cells are given different mechanical properties, tensile forces develop along the veins during growth, causing the network to deform progressively. Our results suggest that the local structure of venation networks results from a reorganization driven by mechanical forces, independently of how veins form. This conclusion is supported by recent observations of vein development in young leaves and by the good quantitative agreement between our simulations and data from mature leaves.
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Affiliation(s)
- Francis Corson
- Laboratoire de Physique Statistique, Ecole Normale Supérieure, UPMC Paris 06, Université Paris Diderot, CNRS, 24 rue Lhomond, 75005 Paris, France.
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Rolland-Lagan AG, Amin M, Pakulska M. Quantifying leaf venation patterns: two-dimensional maps. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2009; 57:195-205. [PMID: 18785998 DOI: 10.1111/j.1365-313x.2008.03678.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The leaf vasculature plays crucial roles in transport and mechanical support. Understanding how vein patterns develop and what underlies pattern variation between species has many implications from both physiological and evolutionary perspectives. We developed a method for extracting spatial vein pattern data from leaf images, such as vein densities and also the sizes and shapes of the vein reticulations. We used this method to quantify leaf venation patterns of the first rosette leaf of Arabidopsis thaliana throughout a series of developmental stages. In particular, we characterized the size and shape of vein network areoles (loops), which enlarge and are split by new veins as a leaf develops. Pattern parameters varied in time and space. In particular, we observed a distal to proximal gradient in loop shape (length/width ratio) which varied over time, and a margin-to-center gradient in loop sizes. Quantitative analyses of vein patterns at the tissue level provide a two-way link between theoretical models of patterning and molecular experimental work to further explore patterning mechanisms during development. Such analyses could also be used to investigate the effect of environmental factors on vein patterns, or to compare venation patterns from different species for evolutionary studies. The method also provides a framework for gathering and overlaying two-dimensional maps of point, line and surface morphological data.
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Sawchuk MG, Donner TJ, Head P, Scarpella E. Unique and overlapping expression patterns among members of photosynthesis-associated nuclear gene families in Arabidopsis. PLANT PHYSIOLOGY 2008; 148:1908-24. [PMID: 18820083 PMCID: PMC2593682 DOI: 10.1104/pp.108.126946] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2008] [Accepted: 09/24/2008] [Indexed: 05/18/2023]
Abstract
Light provides crucial positional information in plant development, and the morphogenetic processes that are orchestrated by light signals are triggered by changes of gene expression in response to variations in light parameters. Control of expression of members of the RbcS and Lhc families of photosynthesis-associated nuclear genes by light cues is a paradigm for light-regulated gene transcription, but high-resolution expression profiles for these gene families are lacking. In this study, we have investigated expression patterns of members of the RbcS and Lhc gene families in Arabidopsis (Arabidopsis thaliana) at the cellular level during undisturbed development and upon controlled interference of the light environment. Members of the RbcS and Lhc gene families are expressed in specialized territories, including root tip, leaf adaxial, abaxial, and epidermal domains, and with distinct chronologies, identifying successive stages of leaf mesophyll ontogeny. Defined spatial and temporal overlap of gene expression fields suggest that the light-harvesting and photosynthetic apparatus may have a different polypeptide composition in different cells and that such composition could change over time even within the same cell.
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Affiliation(s)
- Megan G Sawchuk
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2E9
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Sakaguchi J, Fukuda H. Cell differentiation in the longitudinal veins and formation of commissural veins in rice (Oryza sativa) and maize (Zea mays). JOURNAL OF PLANT RESEARCH 2008; 121:593-602. [PMID: 18932023 DOI: 10.1007/s10265-008-0189-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2008] [Accepted: 09/18/2008] [Indexed: 05/20/2023]
Abstract
Vascular development is a central theme in plant science. However, little is known about the mechanism of vascular development in monocotyledons (compared with dicotyledons). Therefore, we investigated sequential processes of differentiation into various different vascular cells by carrying out detailed observations using serial sections of the bases of developing leaves of rice and maize. The developmental process of the longitudinal vascular bundles was divided into six stages in rice and five stages in maize. The initiation of differentiation into procambial progenitor cells forming the commissural vein arose in a circular layer cell that was adjacent to both a metaxylem vessel and one or a few phloem cells in stage V longitudinal vascular bundles. In most cases the differentiation of ground meristem cells into procambial progenitor cells extended in one direction, toward the next longitudinal vascular bundle, and subsequent periclinal divisions and further differentiation produced a vessel element, two companion cells and a sieve element to form a commissural vein. These results suggest the presence of an intercellular signal(s) that induces differentiation of the circular layer cell and the ground meristem cells into procambial progenitor cells, forming a commissural vein sequentially.
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Affiliation(s)
- Jun Sakaguchi
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
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