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Voiniciuc C, Günl M, Schmidt MHW, Usadel B. Highly Branched Xylan Made by IRREGULAR XYLEM14 and MUCILAGE-RELATED21 Links Mucilage to Arabidopsis Seeds. PLANT PHYSIOLOGY 2015; 169:2481-95. [PMID: 26482889 PMCID: PMC4677919 DOI: 10.1104/pp.15.01441] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 10/17/2015] [Indexed: 05/07/2023]
Abstract
All cells of terrestrial plants are fortified by walls composed of crystalline cellulose microfibrils and a variety of matrix polymers. Xylans are the second most abundant type of polysaccharides on Earth. Previous studies of Arabidopsis (Arabidopsis thaliana) irregular xylem (irx) mutants, with collapsed xylem vessels and dwarfed stature, highlighted the importance of this cell wall component and revealed multiple players required for its synthesis. Nevertheless, xylan elongation and substitution are complex processes that remain poorly understood. Recently, seed coat epidermal cells were shown to provide an excellent system for deciphering hemicellulose production. Using a coexpression and sequence-based strategy, we predicted several MUCILAGE-RELATED (MUCI) genes that encode glycosyltransferases (GTs) involved in the production of xylan. We now show that MUCI21, a member of an uncharacterized clade of the GT61 family, and IRX14 (GT43 protein) are essential for the synthesis of highly branched xylan in seed coat epidermal cells. Our results reveal that xylan is the most abundant xylose-rich component in Arabidopsis seed mucilage and is required to maintain its architecture. Characterization of muci21 and irx14 single and double mutants indicates that MUCI21 is a Golgi-localized protein that likely facilitates the addition of xylose residues directly to the xylan backbone. These unique branches seem to be necessary for pectin attachment to the seed surface, while the xylan backbone maintains cellulose distribution. Evaluation of muci21 and irx14 alongside mutants that disrupt other wall components suggests that mucilage adherence is maintained by complex interactions between several polymers: cellulose, xylans, pectins, and glycoproteins.
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Affiliation(s)
- Cătălin Voiniciuc
- Institute for Bio- and Geosciences (IBG-2: Plant Sciences), Forschungszentrum Jülich, 52425 Jülich, Germany (C.V., M.G., M.H.-W.S., B.U.); andInstitute for Botany and Molecular Genetics, BioEconomy Science Center, RWTH Aachen University, 52074 Aachen, Germany (C.V., M.H.-W.S, B.U.)
| | - Markus Günl
- Institute for Bio- and Geosciences (IBG-2: Plant Sciences), Forschungszentrum Jülich, 52425 Jülich, Germany (C.V., M.G., M.H.-W.S., B.U.); andInstitute for Botany and Molecular Genetics, BioEconomy Science Center, RWTH Aachen University, 52074 Aachen, Germany (C.V., M.H.-W.S, B.U.)
| | - Maximilian Heinrich-Wilhelm Schmidt
- Institute for Bio- and Geosciences (IBG-2: Plant Sciences), Forschungszentrum Jülich, 52425 Jülich, Germany (C.V., M.G., M.H.-W.S., B.U.); andInstitute for Botany and Molecular Genetics, BioEconomy Science Center, RWTH Aachen University, 52074 Aachen, Germany (C.V., M.H.-W.S, B.U.)
| | - Björn Usadel
- Institute for Bio- and Geosciences (IBG-2: Plant Sciences), Forschungszentrum Jülich, 52425 Jülich, Germany (C.V., M.G., M.H.-W.S., B.U.); andInstitute for Botany and Molecular Genetics, BioEconomy Science Center, RWTH Aachen University, 52074 Aachen, Germany (C.V., M.H.-W.S, B.U.)
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Shinohara N, Kakegawa K, Fukuda H. Monoclonal antibody-based analysis of cell wall remodeling during xylogenesis. JOURNAL OF PLANT RESEARCH 2015; 128:975-986. [PMID: 26464036 DOI: 10.1007/s10265-015-0758-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Accepted: 06/19/2015] [Indexed: 06/05/2023]
Abstract
Xylogenesis, a process by which woody tissues are formed, entails qualitative and quantitative changes in the cell wall. However, the molecular events that underlie these changes are not completely understood. Previously, we have isolated two monoclonal antibodies, referred to as XD3 and XD27, by subtractive screening of a phage-display library of antibodies raised against a wall fraction of Zinnia elegans xylogenic culture cells. Here we report the biochemical and immunohistochemical characterization of those antibodies. The antibody XD3 recognized (1→4)-β-D-galactan in pectin fraction. During xylogenesis, the XD3 epitope was localized to the primary wall of tracheary-element precursor cells, which undergo substantial cell elongation, and was absent from mature tracheary elements. XD27 recognized an arabinogalactan protein that was bound strongly to a germin-like protein. The XD27 epitope was localized to pre-lignified secondary walls of tracheary elements. Thus these cell-wall-directed monoclonal antibodies revealed two molecular events during xylogenesis. The biological significance of these events is discussed in relation to current views of the plant cell wall.
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Huang D, Wang C, Yuan J, Cao J, Lan H. Differentiation of the seed coat and composition of the mucilage of Lepidium perfoliatum L.: a desert annual with typical myxospermy. Acta Biochim Biophys Sin (Shanghai) 2015; 47:775-87. [PMID: 26341978 DOI: 10.1093/abbs/gmv078] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2015] [Accepted: 05/21/2015] [Indexed: 11/12/2022] Open
Abstract
Myxospermy is an important feature in seeds of many plant species grown in desert region. Fertilization can initiate differentiation of the seed coat epidermis into a specialized cell type with mucilage production. In the present study, comprehensive analyses were performed on the seed coat differentiation, mucilage production and composition, and seed germination in Lepidium perfoliatum (Brassicaceae), a desert annual with typical myxospermy in China. First, results indicated that mucilage was secreted uniformly at the outer tangential wall, resulting in compression of the cytoplasm to the bottom of the epidermal cells. Secondly, the inner tangential wall and two radial walls of the subepidermal cells were apparently thickened by production of a secondary cell wall material, which resulted in a 'typical' palisade appearance. Thirdly, immunohistochemical staining combined with the enzymatic digestion and infrared spectrum analysis of the mucilage indicated that, while one important component of the seed coat mucilage in L. perfoliatum was pectin, it also contained β-1,3-d-glucan and xyloglucan. Finally, seed germination showed that seeds with mucilage displayed significantly higher germination percentage than that of demucilaged seeds in abundant or excess water conditions. These results suggest that the possible ecological role of mucilage in L. perfoliatum is in the adaptation to habitats with well-watered and water-logged conditions, rather than water stress.
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Affiliation(s)
- Daihong Huang
- Xinjiang Key Laboratory of Biological Resources and Genetic Engineering, College of Life Science and Technology, Xinjiang University, Urumqi 830046, China College of Life Science, Nankai University, Tianjin 300071, China
| | - Cui Wang
- Xinjiang Key Laboratory of Biological Resources and Genetic Engineering, College of Life Science and Technology, Xinjiang University, Urumqi 830046, China
| | - Junwen Yuan
- Xinjiang Key Laboratory of Biological Resources and Genetic Engineering, College of Life Science and Technology, Xinjiang University, Urumqi 830046, China
| | - Jing Cao
- Xinjiang Key Laboratory of Biological Resources and Genetic Engineering, College of Life Science and Technology, Xinjiang University, Urumqi 830046, China
| | - Haiyan Lan
- Xinjiang Key Laboratory of Biological Resources and Genetic Engineering, College of Life Science and Technology, Xinjiang University, Urumqi 830046, China
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Francoz E, Ranocha P, Burlat V, Dunand C. Arabidopsis seed mucilage secretory cells: regulation and dynamics. TRENDS IN PLANT SCIENCE 2015; 20:515-24. [PMID: 25998090 DOI: 10.1016/j.tplants.2015.04.008] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 03/02/2015] [Accepted: 04/15/2015] [Indexed: 05/21/2023]
Abstract
Seeds from various angiosperm species produce polysaccharide mucilage facilitating germination and, therefore, conferring major evolutionary advantages. The seed epidermal mucilage secretory cells (MSCs) undergo numerous tightly controlled changes of their extracellular matrixes (ECMs) throughout seed development. Recently, major progress based on the model species Arabidopsis thaliana was published, including the identification of 54 genes necessary for mucilage synthesis and release. Here, we review these genes that constitute the so-called 'MSC toolbox', within which transcription factors and proteins related to polysaccharide production, secretion, modification, and stabilization are the most abundant and belong to complex regulatory networks. We also discuss how seed coat 'omics data-mining, comparative genomics, and operon-like gene cluster studies will provide means to identify new members of the MSC toolbox.
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Affiliation(s)
- Edith Francoz
- Université de Toulouse, UPS, UMR 5546, Laboratoire de Recherche en Sciences Végétales, BP 42617, F-31326 Castanet-Tolosan, France; CNRS, UMR 5546, BP 42617, F-31326 Castanet-Tolosan, France
| | - Philippe Ranocha
- Université de Toulouse, UPS, UMR 5546, Laboratoire de Recherche en Sciences Végétales, BP 42617, F-31326 Castanet-Tolosan, France; CNRS, UMR 5546, BP 42617, F-31326 Castanet-Tolosan, France
| | - Vincent Burlat
- Université de Toulouse, UPS, UMR 5546, Laboratoire de Recherche en Sciences Végétales, BP 42617, F-31326 Castanet-Tolosan, France; CNRS, UMR 5546, BP 42617, F-31326 Castanet-Tolosan, France.
| | - Christophe Dunand
- Université de Toulouse, UPS, UMR 5546, Laboratoire de Recherche en Sciences Végétales, BP 42617, F-31326 Castanet-Tolosan, France; CNRS, UMR 5546, BP 42617, F-31326 Castanet-Tolosan, France.
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Griffiths JS, Šola K, Kushwaha R, Lam P, Tateno M, Young R, Voiniciuc C, Dean G, Mansfield SD, DeBolt S, Haughn GW. Unidirectional movement of cellulose synthase complexes in Arabidopsis seed coat epidermal cells deposit cellulose involved in mucilage extrusion, adherence, and ray formation. PLANT PHYSIOLOGY 2015; 168:502-20. [PMID: 25926481 PMCID: PMC4453796 DOI: 10.1104/pp.15.00478] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2015] [Accepted: 04/28/2015] [Indexed: 05/17/2023]
Abstract
Cellulose synthase5 (CESA5) synthesizes cellulose necessary for seed mucilage adherence to seed coat epidermal cells of Arabidopsis (Arabidopsis thaliana). The involvement of additional CESA proteins in this process and details concerning the manner in which cellulose is deposited in the mucilage pocket are unknown. Here, we show that both CESA3 and CESA10 are highly expressed in this cell type at the time of mucilage synthesis and localize to the plasma membrane adjacent to the mucilage pocket. The isoxaben resistant1-1 and isoxaben resistant1-2 mutants affecting CESA3 show defects consistent with altered mucilage cellulose biosynthesis. CESA3 can interact with CESA5 in vitro, and green fluorescent protein-tagged CESA5, CESA3, and CESA10 proteins move in a linear, unidirectional fashion around the cytoplasmic column of the cell, parallel with the surface of the seed, in a pattern similar to that of cortical microtubules. Consistent with this movement, cytological evidence suggests that the mucilage is coiled around the columella and unwinds during mucilage extrusion to form a linear ray. Mutations in CESA5 and CESA3 affect the speed of mucilage extrusion and mucilage adherence. These findings imply that cellulose fibrils are synthesized in an ordered helical array around the columella, providing a distinct structure to the mucilage that is important for both mucilage extrusion and adherence.
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Affiliation(s)
- Jonathan S Griffiths
- Department of Botany (J.S.G., K.Š., P.L., R.Y., C.V., G.D., G.W.H.) and Department of Wood Science (S.D.M.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4; andDepartment of Horticulture Plant Physiology/Biochemistry/Molecular Biology Program (R.K., M.T., S.D.) and University of Kentucky Seed Biology Group (R.K., M.T., S.D.), University of Kentucky, Lexington, Kentucky 40546
| | - Krešimir Šola
- Department of Botany (J.S.G., K.Š., P.L., R.Y., C.V., G.D., G.W.H.) and Department of Wood Science (S.D.M.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4; andDepartment of Horticulture Plant Physiology/Biochemistry/Molecular Biology Program (R.K., M.T., S.D.) and University of Kentucky Seed Biology Group (R.K., M.T., S.D.), University of Kentucky, Lexington, Kentucky 40546
| | - Rekha Kushwaha
- Department of Botany (J.S.G., K.Š., P.L., R.Y., C.V., G.D., G.W.H.) and Department of Wood Science (S.D.M.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4; andDepartment of Horticulture Plant Physiology/Biochemistry/Molecular Biology Program (R.K., M.T., S.D.) and University of Kentucky Seed Biology Group (R.K., M.T., S.D.), University of Kentucky, Lexington, Kentucky 40546
| | - Patricia Lam
- Department of Botany (J.S.G., K.Š., P.L., R.Y., C.V., G.D., G.W.H.) and Department of Wood Science (S.D.M.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4; andDepartment of Horticulture Plant Physiology/Biochemistry/Molecular Biology Program (R.K., M.T., S.D.) and University of Kentucky Seed Biology Group (R.K., M.T., S.D.), University of Kentucky, Lexington, Kentucky 40546
| | - Mizuki Tateno
- Department of Botany (J.S.G., K.Š., P.L., R.Y., C.V., G.D., G.W.H.) and Department of Wood Science (S.D.M.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4; andDepartment of Horticulture Plant Physiology/Biochemistry/Molecular Biology Program (R.K., M.T., S.D.) and University of Kentucky Seed Biology Group (R.K., M.T., S.D.), University of Kentucky, Lexington, Kentucky 40546
| | - Robin Young
- Department of Botany (J.S.G., K.Š., P.L., R.Y., C.V., G.D., G.W.H.) and Department of Wood Science (S.D.M.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4; andDepartment of Horticulture Plant Physiology/Biochemistry/Molecular Biology Program (R.K., M.T., S.D.) and University of Kentucky Seed Biology Group (R.K., M.T., S.D.), University of Kentucky, Lexington, Kentucky 40546
| | - Cătălin Voiniciuc
- Department of Botany (J.S.G., K.Š., P.L., R.Y., C.V., G.D., G.W.H.) and Department of Wood Science (S.D.M.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4; andDepartment of Horticulture Plant Physiology/Biochemistry/Molecular Biology Program (R.K., M.T., S.D.) and University of Kentucky Seed Biology Group (R.K., M.T., S.D.), University of Kentucky, Lexington, Kentucky 40546
| | - Gillian Dean
- Department of Botany (J.S.G., K.Š., P.L., R.Y., C.V., G.D., G.W.H.) and Department of Wood Science (S.D.M.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4; andDepartment of Horticulture Plant Physiology/Biochemistry/Molecular Biology Program (R.K., M.T., S.D.) and University of Kentucky Seed Biology Group (R.K., M.T., S.D.), University of Kentucky, Lexington, Kentucky 40546
| | - Shawn D Mansfield
- Department of Botany (J.S.G., K.Š., P.L., R.Y., C.V., G.D., G.W.H.) and Department of Wood Science (S.D.M.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4; andDepartment of Horticulture Plant Physiology/Biochemistry/Molecular Biology Program (R.K., M.T., S.D.) and University of Kentucky Seed Biology Group (R.K., M.T., S.D.), University of Kentucky, Lexington, Kentucky 40546
| | - Seth DeBolt
- Department of Botany (J.S.G., K.Š., P.L., R.Y., C.V., G.D., G.W.H.) and Department of Wood Science (S.D.M.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4; andDepartment of Horticulture Plant Physiology/Biochemistry/Molecular Biology Program (R.K., M.T., S.D.) and University of Kentucky Seed Biology Group (R.K., M.T., S.D.), University of Kentucky, Lexington, Kentucky 40546
| | - George W Haughn
- Department of Botany (J.S.G., K.Š., P.L., R.Y., C.V., G.D., G.W.H.) and Department of Wood Science (S.D.M.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4; andDepartment of Horticulture Plant Physiology/Biochemistry/Molecular Biology Program (R.K., M.T., S.D.) and University of Kentucky Seed Biology Group (R.K., M.T., S.D.), University of Kentucky, Lexington, Kentucky 40546
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Voiniciuc C, Yang B, Schmidt MHW, Günl M, Usadel B. Starting to gel: how Arabidopsis seed coat epidermal cells produce specialized secondary cell walls. Int J Mol Sci 2015; 16:3452-73. [PMID: 25658798 PMCID: PMC4346907 DOI: 10.3390/ijms16023452] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Revised: 01/22/2015] [Accepted: 01/29/2015] [Indexed: 11/30/2022] Open
Abstract
For more than a decade, the Arabidopsis seed coat epidermis (SCE) has been used as a model system to study the synthesis, secretion and modification of cell wall polysaccharides, particularly pectin. Our detailed re-evaluation of available biochemical data highlights that Arabidopsis seed mucilage is more than just pectin. Typical secondary wall polymers such as xylans and heteromannans are also present in mucilage. Despite their low abundance, these components appear to play essential roles in controlling mucilage properties, and should be further investigated. We also provide a comprehensive community resource by re-assessing the mucilage phenotypes of almost 20 mutants using the same conditions. We conduct an in-depth functional evaluation of all the SCE genes described in the literature and propose a revised model for mucilage production. Further investigation of SCE cells will improve our understanding of plant cell walls.
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Affiliation(s)
- Cătălin Voiniciuc
- Institute for Bio- and Geosciences (IBG-2: Plant Sciences), Forschungszentrum Jülich, 52425 Jülich, Germany.
- Institute for Botany and Molecular Genetics (IBMG), RWTH Aachen University, 52056 Aachen, Germany.
| | - Bo Yang
- Institute for Botany and Molecular Genetics (IBMG), RWTH Aachen University, 52056 Aachen, Germany.
| | - Maximilian Heinrich-Wilhelm Schmidt
- Institute for Bio- and Geosciences (IBG-2: Plant Sciences), Forschungszentrum Jülich, 52425 Jülich, Germany.
- Institute for Botany and Molecular Genetics (IBMG), RWTH Aachen University, 52056 Aachen, Germany.
| | - Markus Günl
- Institute for Bio- and Geosciences (IBG-2: Plant Sciences), Forschungszentrum Jülich, 52425 Jülich, Germany.
| | - Björn Usadel
- Institute for Bio- and Geosciences (IBG-2: Plant Sciences), Forschungszentrum Jülich, 52425 Jülich, Germany.
- Institute for Botany and Molecular Genetics (IBMG), RWTH Aachen University, 52056 Aachen, Germany.
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Leroux C, Bouton S, Kiefer-Meyer MC, Fabrice TN, Mareck A, Guénin S, Fournet F, Ringli C, Pelloux J, Driouich A, Lerouge P, Lehner A, Mollet JC. PECTIN METHYLESTERASE48 is involved in Arabidopsis pollen grain germination. PLANT PHYSIOLOGY 2015; 167:367-80. [PMID: 25524442 PMCID: PMC4326738 DOI: 10.1104/pp.114.250928] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Accepted: 12/16/2014] [Indexed: 05/18/2023]
Abstract
Germination of pollen grains is a crucial step in plant reproduction. However, the molecular mechanisms involved remain unclear. We investigated the role of PECTIN METHYLESTERASE48 (PME48), an enzyme implicated in the remodeling of pectins in Arabidopsis (Arabidopsis thaliana) pollen. A combination of functional genomics, gene expression, in vivo and in vitro pollen germination, immunolabeling, and biochemical analyses was used on wild-type and Atpme48 mutant plants. We showed that AtPME48 is specifically expressed in the male gametophyte and is the second most expressed PME in dry and imbibed pollen grains. Pollen grains from homozygous mutant lines displayed a significant delay in imbibition and germination in vitro and in vivo. Moreover, numerous pollen grains showed two tips emerging instead of one in the wild type. Immunolabeling and Fourier transform infrared analyses showed that the degree of methylesterification of the homogalacturonan was higher in pme48-/- pollen grains. In contrast, the PME activity was lower in pme48-/-, partly due to a reduction of PME48 activity revealed by zymogram. Interestingly, the wild-type phenotype was restored in pme48-/- with the optimum germination medium supplemented with 2.5 mm calcium chloride, suggesting that in the wild-type pollen, the weakly methylesterified homogalacturonan is a source of Ca(2+) necessary for pollen germination. Although pollen-specific PMEs are traditionally associated with pollen tube elongation, this study provides strong evidence that PME48 impacts the mechanical properties of the intine wall during maturation of the pollen grain, which, in turn, influences pollen grain germination.
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Affiliation(s)
- Christelle Leroux
- Laboratoire Glycobiologie et Matrice Extracellulaire, Normandie Université, Institute for Research and Innovation in Biomedicine, Végétal, Agronomie, Sol, et Innovation, 76821 Mont-Saint-Aignan, France (C.L., M.-C.K.-M., A.M., A.D., P.L., A.L., J.-C.M.);Unité Biologie des Plantes et Innovation (S.B., S.G., F.F., J.P.) and Centre de Ressources Régionales en Biologie Moléculaire (S.G.), Université de Picardie Jules Verne, 80039 Amiens, France; andInstitute of Plant Biology, University of Zürich, 8008 Zurich, Switzerland (T.N.F., C.R.)
| | - Sophie Bouton
- Laboratoire Glycobiologie et Matrice Extracellulaire, Normandie Université, Institute for Research and Innovation in Biomedicine, Végétal, Agronomie, Sol, et Innovation, 76821 Mont-Saint-Aignan, France (C.L., M.-C.K.-M., A.M., A.D., P.L., A.L., J.-C.M.);Unité Biologie des Plantes et Innovation (S.B., S.G., F.F., J.P.) and Centre de Ressources Régionales en Biologie Moléculaire (S.G.), Université de Picardie Jules Verne, 80039 Amiens, France; andInstitute of Plant Biology, University of Zürich, 8008 Zurich, Switzerland (T.N.F., C.R.)
| | - Marie-Christine Kiefer-Meyer
- Laboratoire Glycobiologie et Matrice Extracellulaire, Normandie Université, Institute for Research and Innovation in Biomedicine, Végétal, Agronomie, Sol, et Innovation, 76821 Mont-Saint-Aignan, France (C.L., M.-C.K.-M., A.M., A.D., P.L., A.L., J.-C.M.);Unité Biologie des Plantes et Innovation (S.B., S.G., F.F., J.P.) and Centre de Ressources Régionales en Biologie Moléculaire (S.G.), Université de Picardie Jules Verne, 80039 Amiens, France; andInstitute of Plant Biology, University of Zürich, 8008 Zurich, Switzerland (T.N.F., C.R.)
| | - Tohnyui Ndinyanka Fabrice
- Laboratoire Glycobiologie et Matrice Extracellulaire, Normandie Université, Institute for Research and Innovation in Biomedicine, Végétal, Agronomie, Sol, et Innovation, 76821 Mont-Saint-Aignan, France (C.L., M.-C.K.-M., A.M., A.D., P.L., A.L., J.-C.M.);Unité Biologie des Plantes et Innovation (S.B., S.G., F.F., J.P.) and Centre de Ressources Régionales en Biologie Moléculaire (S.G.), Université de Picardie Jules Verne, 80039 Amiens, France; andInstitute of Plant Biology, University of Zürich, 8008 Zurich, Switzerland (T.N.F., C.R.)
| | - Alain Mareck
- Laboratoire Glycobiologie et Matrice Extracellulaire, Normandie Université, Institute for Research and Innovation in Biomedicine, Végétal, Agronomie, Sol, et Innovation, 76821 Mont-Saint-Aignan, France (C.L., M.-C.K.-M., A.M., A.D., P.L., A.L., J.-C.M.);Unité Biologie des Plantes et Innovation (S.B., S.G., F.F., J.P.) and Centre de Ressources Régionales en Biologie Moléculaire (S.G.), Université de Picardie Jules Verne, 80039 Amiens, France; andInstitute of Plant Biology, University of Zürich, 8008 Zurich, Switzerland (T.N.F., C.R.)
| | - Stéphanie Guénin
- Laboratoire Glycobiologie et Matrice Extracellulaire, Normandie Université, Institute for Research and Innovation in Biomedicine, Végétal, Agronomie, Sol, et Innovation, 76821 Mont-Saint-Aignan, France (C.L., M.-C.K.-M., A.M., A.D., P.L., A.L., J.-C.M.);Unité Biologie des Plantes et Innovation (S.B., S.G., F.F., J.P.) and Centre de Ressources Régionales en Biologie Moléculaire (S.G.), Université de Picardie Jules Verne, 80039 Amiens, France; andInstitute of Plant Biology, University of Zürich, 8008 Zurich, Switzerland (T.N.F., C.R.)
| | - Françoise Fournet
- Laboratoire Glycobiologie et Matrice Extracellulaire, Normandie Université, Institute for Research and Innovation in Biomedicine, Végétal, Agronomie, Sol, et Innovation, 76821 Mont-Saint-Aignan, France (C.L., M.-C.K.-M., A.M., A.D., P.L., A.L., J.-C.M.);Unité Biologie des Plantes et Innovation (S.B., S.G., F.F., J.P.) and Centre de Ressources Régionales en Biologie Moléculaire (S.G.), Université de Picardie Jules Verne, 80039 Amiens, France; andInstitute of Plant Biology, University of Zürich, 8008 Zurich, Switzerland (T.N.F., C.R.)
| | - Christoph Ringli
- Laboratoire Glycobiologie et Matrice Extracellulaire, Normandie Université, Institute for Research and Innovation in Biomedicine, Végétal, Agronomie, Sol, et Innovation, 76821 Mont-Saint-Aignan, France (C.L., M.-C.K.-M., A.M., A.D., P.L., A.L., J.-C.M.);Unité Biologie des Plantes et Innovation (S.B., S.G., F.F., J.P.) and Centre de Ressources Régionales en Biologie Moléculaire (S.G.), Université de Picardie Jules Verne, 80039 Amiens, France; andInstitute of Plant Biology, University of Zürich, 8008 Zurich, Switzerland (T.N.F., C.R.)
| | - Jérôme Pelloux
- Laboratoire Glycobiologie et Matrice Extracellulaire, Normandie Université, Institute for Research and Innovation in Biomedicine, Végétal, Agronomie, Sol, et Innovation, 76821 Mont-Saint-Aignan, France (C.L., M.-C.K.-M., A.M., A.D., P.L., A.L., J.-C.M.);Unité Biologie des Plantes et Innovation (S.B., S.G., F.F., J.P.) and Centre de Ressources Régionales en Biologie Moléculaire (S.G.), Université de Picardie Jules Verne, 80039 Amiens, France; andInstitute of Plant Biology, University of Zürich, 8008 Zurich, Switzerland (T.N.F., C.R.)
| | - Azeddine Driouich
- Laboratoire Glycobiologie et Matrice Extracellulaire, Normandie Université, Institute for Research and Innovation in Biomedicine, Végétal, Agronomie, Sol, et Innovation, 76821 Mont-Saint-Aignan, France (C.L., M.-C.K.-M., A.M., A.D., P.L., A.L., J.-C.M.);Unité Biologie des Plantes et Innovation (S.B., S.G., F.F., J.P.) and Centre de Ressources Régionales en Biologie Moléculaire (S.G.), Université de Picardie Jules Verne, 80039 Amiens, France; andInstitute of Plant Biology, University of Zürich, 8008 Zurich, Switzerland (T.N.F., C.R.)
| | - Patrice Lerouge
- Laboratoire Glycobiologie et Matrice Extracellulaire, Normandie Université, Institute for Research and Innovation in Biomedicine, Végétal, Agronomie, Sol, et Innovation, 76821 Mont-Saint-Aignan, France (C.L., M.-C.K.-M., A.M., A.D., P.L., A.L., J.-C.M.);Unité Biologie des Plantes et Innovation (S.B., S.G., F.F., J.P.) and Centre de Ressources Régionales en Biologie Moléculaire (S.G.), Université de Picardie Jules Verne, 80039 Amiens, France; andInstitute of Plant Biology, University of Zürich, 8008 Zurich, Switzerland (T.N.F., C.R.)
| | - Arnaud Lehner
- Laboratoire Glycobiologie et Matrice Extracellulaire, Normandie Université, Institute for Research and Innovation in Biomedicine, Végétal, Agronomie, Sol, et Innovation, 76821 Mont-Saint-Aignan, France (C.L., M.-C.K.-M., A.M., A.D., P.L., A.L., J.-C.M.);Unité Biologie des Plantes et Innovation (S.B., S.G., F.F., J.P.) and Centre de Ressources Régionales en Biologie Moléculaire (S.G.), Université de Picardie Jules Verne, 80039 Amiens, France; andInstitute of Plant Biology, University of Zürich, 8008 Zurich, Switzerland (T.N.F., C.R.)
| | - Jean-Claude Mollet
- Laboratoire Glycobiologie et Matrice Extracellulaire, Normandie Université, Institute for Research and Innovation in Biomedicine, Végétal, Agronomie, Sol, et Innovation, 76821 Mont-Saint-Aignan, France (C.L., M.-C.K.-M., A.M., A.D., P.L., A.L., J.-C.M.);Unité Biologie des Plantes et Innovation (S.B., S.G., F.F., J.P.) and Centre de Ressources Régionales en Biologie Moléculaire (S.G.), Université de Picardie Jules Verne, 80039 Amiens, France; andInstitute of Plant Biology, University of Zürich, 8008 Zurich, Switzerland (T.N.F., C.R.)
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North HM, Berger A, Saez-Aguayo S, Ralet MC. Understanding polysaccharide production and properties using seed coat mutants: future perspectives for the exploitation of natural variants. ANNALS OF BOTANY 2014; 114:1251-63. [PMID: 24607722 PMCID: PMC4195541 DOI: 10.1093/aob/mcu011] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Accepted: 01/14/2014] [Indexed: 05/17/2023]
Abstract
BACKGROUND The epidermal cells of the seed coat of certain species accumulate polysaccharides during seed development for cell wall reinforcement or release on imbibition to form mucilage. Seed-coat epidermal cells show natural variation in their structure and mucilage production, which could explain the diverse ecophysiological roles proposed for the latter. Arabidopsis mucilage mutants have proved to be an important tool for the identification of genes involved in the production of seed-coat polysaccharides. SCOPE This review documents genes that have been characterized as playing a role in the differentiation of the epidermal cells of the arabidopsis seed coat, the natural variability in polysaccharide features of these cells and the physiological roles attributed to seed mucilage. CONCLUSIONS Seed-coat epidermal cells are an excellent model for the study of polysaccharide metabolism and properties. Intra- and interspecies natural variation in the differentiation of these epidermal cells is an under-exploited resource for such studies and promises to play an important part in improving our knowledge of polysaccharide production and ecophysiological function.
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Affiliation(s)
- Helen M North
- INRA, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, F-78026 Versailles, France AgroParisTech, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, F-78026 Versailles, France
| | - Adeline Berger
- INRA, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, F-78026 Versailles, France AgroParisTech, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, F-78026 Versailles, France
| | - Susana Saez-Aguayo
- INRA, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, F-78026 Versailles, France AgroParisTech, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, F-78026 Versailles, France
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60
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Pavlov A, Paynel F, Rihouey C, Porokhovinova E, Brutch N, Morvan C. Variability of seed traits and properties of soluble mucilages in lines of the flax genetic collection of Vavilov Institute. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2014; 80:348-361. [PMID: 24852819 DOI: 10.1016/j.plaphy.2014.04.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Accepted: 04/26/2014] [Indexed: 06/03/2023]
Abstract
Upon hydration, flax seeds secrete mucilages whose content and physico-chemical properties vary according to the genotype and environment. The aim of the work was to investigate the complex genetic relationships between the vegetative period, colour, size and production of seed, the composition (polysaccharides and proteins) and physico-chemical properties of soluble mucilages collected at 28 °C from seeds of 18 lines grown in St Petersburg area. The vegetative period duration was found to impact the size and production of seeds, the yield of mucilages, including the polysaccharides, and the galactosidase enzymes, as well as their composition (mainly the rhamnogalacturonan I moieties) and some of their properties (mainly viscosity). Data allowed to significantly distinguish 6 fibre lines with mucilages enriched in rhamnogalacturonan I, 6 lines with mucilages enriched in arabinoxylan including 5 linseeds and 1 mutated fibre-line, and 5 lines with mucilages enriched in homogalacturonan-like polymer including 4 fibre lines and 1 brown linseed. Seven fibre lines had mucilages particularly rich in galactose. High to very high variability was found for 14 traits. Relatively independent characters (form/shape, protein and galactosidase) were identified and could be combined by breeding, with a focus on mucilage yield, composition and properties. Main-component analyses of line characters showed a large diversity in linseeds mainly due to their different origin but small variation in Russian fibre lines with brown seeds.
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Affiliation(s)
- A Pavlov
- Department of Oil and Fiber Crops, N.I.Vavilov Research Institute of Plant Industry, 190000, B. Morskaya, 42, Saint-Petersburg, Russia.
| | - F Paynel
- University of Rouen, Chemistry Laboratory PBS, UMR 6270, CNRS, FR 3038, 76821 Mont-Saint-Aignan, France.
| | - C Rihouey
- University of Rouen, Chemistry Laboratory PBS, UMR 6270, CNRS, FR 3038, 76821 Mont-Saint-Aignan, France.
| | - E Porokhovinova
- Department of Oil and Fiber Crops, N.I.Vavilov Research Institute of Plant Industry, 190000, B. Morskaya, 42, Saint-Petersburg, Russia.
| | - N Brutch
- Department of Oil and Fiber Crops, N.I.Vavilov Research Institute of Plant Industry, 190000, B. Morskaya, 42, Saint-Petersburg, Russia.
| | - C Morvan
- University of Rouen, Chemistry Laboratory PBS, UMR 6270, CNRS, FR 3038, 76821 Mont-Saint-Aignan, France.
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61
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Griffiths JS, Tsai AYL, Xue H, Voiniciuc C, Sola K, Seifert GJ, Mansfield SD, Haughn GW. SALT-OVERLY SENSITIVE5 Mediates Arabidopsis Seed Coat Mucilage Adherence and Organization through Pectins. PLANT PHYSIOLOGY 2014; 165:991-1004. [PMID: 24808103 PMCID: PMC4081351 DOI: 10.1104/pp.114.239400] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Accepted: 04/29/2014] [Indexed: 05/17/2023]
Abstract
Interactions between cell wall polymers are critical for establishing cell wall integrity and cell-cell adhesion. Here, we exploit the Arabidopsis (Arabidopsis thaliana) seed coat mucilage system to examine cell wall polymer interactions. On hydration, seeds release an adherent mucilage layer strongly attached to the seed in addition to a nonadherent layer that can be removed by gentle agitation. Rhamnogalacturonan I (RG I) is the primary component of adherent mucilage, with homogalacturonan, cellulose, and xyloglucan constituting minor components. Adherent mucilage contains rays composed of cellulose and pectin that extend above the center of each epidermal cell. CELLULOSE SYNTHASE5 (CESA5) and the arabinogalactan protein SALT-OVERLY SENSITIVE5 (SOS5) are required for mucilage adherence through unknown mechanisms. SOS5 has been suggested to mediate adherence by influencing cellulose biosynthesis. We, therefore, investigated the relationship between SOS5 and CESA5. cesa5-1 seeds show reduced cellulose, RG I, and ray size in adherent mucilage. In contrast, sos5-2 seeds have wild-type levels of cellulose but completely lack adherent RG I and rays. Thus, relative to each other, cesa5-1 has a greater effect on cellulose, whereas sos5-2 mainly affects pectin. The double mutant cesa5-1 sos5-2 has a much more severe loss of mucilage adherence, suggesting that SOS5 and CESA5 function independently. Double-mutant analyses with mutations in MUCILAGE MODIFIED2 and FLYING SAUCER1 that reduce mucilage release through pectin modification suggest that only SOS5 influences pectin-mediated adherence. Together, these findings suggest that SOS5 mediates adherence through pectins and does so independently of but in concert with cellulose synthesized by CESA5.
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Affiliation(s)
- Jonathan S Griffiths
- Departments of Botany (J.S.G., A.Y.-L.T., C.V., K.S., G.W.H.) andWood Science (S.D.M.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4; andDepartment of Applied Genetics and Cell Biology, University of Natural Resources and Life Science, A-1990 Vienna, Austria (H.X., G.J.S.)
| | - Allen Yi-Lun Tsai
- Departments of Botany (J.S.G., A.Y.-L.T., C.V., K.S., G.W.H.) andWood Science (S.D.M.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4; andDepartment of Applied Genetics and Cell Biology, University of Natural Resources and Life Science, A-1990 Vienna, Austria (H.X., G.J.S.)
| | - Hui Xue
- Departments of Botany (J.S.G., A.Y.-L.T., C.V., K.S., G.W.H.) andWood Science (S.D.M.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4; andDepartment of Applied Genetics and Cell Biology, University of Natural Resources and Life Science, A-1990 Vienna, Austria (H.X., G.J.S.)
| | - Cătălin Voiniciuc
- Departments of Botany (J.S.G., A.Y.-L.T., C.V., K.S., G.W.H.) andWood Science (S.D.M.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4; andDepartment of Applied Genetics and Cell Biology, University of Natural Resources and Life Science, A-1990 Vienna, Austria (H.X., G.J.S.)
| | - Krešimir Sola
- Departments of Botany (J.S.G., A.Y.-L.T., C.V., K.S., G.W.H.) andWood Science (S.D.M.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4; andDepartment of Applied Genetics and Cell Biology, University of Natural Resources and Life Science, A-1990 Vienna, Austria (H.X., G.J.S.)
| | - Georg J Seifert
- Departments of Botany (J.S.G., A.Y.-L.T., C.V., K.S., G.W.H.) andWood Science (S.D.M.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4; andDepartment of Applied Genetics and Cell Biology, University of Natural Resources and Life Science, A-1990 Vienna, Austria (H.X., G.J.S.)
| | - Shawn D Mansfield
- Departments of Botany (J.S.G., A.Y.-L.T., C.V., K.S., G.W.H.) andWood Science (S.D.M.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4; andDepartment of Applied Genetics and Cell Biology, University of Natural Resources and Life Science, A-1990 Vienna, Austria (H.X., G.J.S.)
| | - George W Haughn
- Departments of Botany (J.S.G., A.Y.-L.T., C.V., K.S., G.W.H.) andWood Science (S.D.M.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4; andDepartment of Applied Genetics and Cell Biology, University of Natural Resources and Life Science, A-1990 Vienna, Austria (H.X., G.J.S.)
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62
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Chen M, Xuan L, Wang Z, Zhou L, Li Z, Du X, Ali E, Zhang G, Jiang L. TRANSPARENT TESTA8 Inhibits Seed Fatty Acid Accumulation by Targeting Several Seed Development Regulators in Arabidopsis. PLANT PHYSIOLOGY 2014; 165:905-916. [PMID: 24722549 PMCID: PMC4044850 DOI: 10.1104/pp.114.235507] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Accepted: 04/04/2014] [Indexed: 05/19/2023]
Abstract
Fatty acids (FAs) and FA-derived complex lipids play important roles in plant growth and vegetative development and are a class of prominent metabolites stored in mature seeds. The factors and regulatory networks that control FA accumulation in plant seeds remain largely unknown. The role of TRANSPARENT TESTA8 (TT8) in the regulation of flavonoid biosynthesis and the formation of seed coat color is extensively studied; however, its function in affecting seed FA biosynthesis is poorly understood. In this article, we show that Arabidopsis (Arabidopsis thaliana) TT8 acts maternally to affect seed FA biosynthesis and inhibits seed FA accumulation by down-regulating a group of genes either critical to embryonic development or important in the FA biosynthesis pathway. Moreover, the tt8 mutation resulted in reduced deposition of protein in seeds during maturation. Posttranslational activation of a TT8-GLUCOCORTICOID RECEPTOR fusion protein and chromatin immunoprecipitation assays demonstrated that TT8 represses the activities of LEAFY COTYLEDON1, LEAFY COTYLEDON2, and FUSCA3, the critical transcriptional factors important for seed development, as well as CYTIDINEDIPHOSPHATE DIACYLGLYCEROL SYNTHASE2, which mediates glycerolipid biosynthesis. These results help us to understand the entire function of TT8 and increase our knowledge of the complicated networks regulating the formation of FA-derived complex lipids in plant seeds.
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Affiliation(s)
- Mingxun Chen
- Key Laboratory of Crop Gene Resources of Zhejiang Province, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, People's Republic of China
| | - Lijie Xuan
- Key Laboratory of Crop Gene Resources of Zhejiang Province, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, People's Republic of China
| | - Zhong Wang
- Key Laboratory of Crop Gene Resources of Zhejiang Province, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, People's Republic of China
| | - Longhua Zhou
- Key Laboratory of Crop Gene Resources of Zhejiang Province, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, People's Republic of China
| | - Zhilan Li
- Key Laboratory of Crop Gene Resources of Zhejiang Province, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, People's Republic of China
| | - Xue Du
- Key Laboratory of Crop Gene Resources of Zhejiang Province, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, People's Republic of China
| | - Essa Ali
- Key Laboratory of Crop Gene Resources of Zhejiang Province, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, People's Republic of China
| | - Guoping Zhang
- Key Laboratory of Crop Gene Resources of Zhejiang Province, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, People's Republic of China
| | - Lixi Jiang
- Key Laboratory of Crop Gene Resources of Zhejiang Province, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, People's Republic of China
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63
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Yu L, Shi D, Li J, Kong Y, Yu Y, Chai G, Hu R, Wang J, Hahn MG, Zhou G. CELLULOSE SYNTHASE-LIKE A2, a glucomannan synthase, is involved in maintaining adherent mucilage structure in Arabidopsis seed. PLANT PHYSIOLOGY 2014; 164:1842-56. [PMID: 24569843 PMCID: PMC3982747 DOI: 10.1104/pp.114.236596] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Accepted: 02/24/2014] [Indexed: 05/17/2023]
Abstract
Mannans are hemicellulosic polysaccharides that are considered to have both structural and storage functions in the plant cell wall. However, it is not yet known how mannans function in Arabidopsis (Arabidopsis thaliana) seed mucilage. In this study, CELLULOSE SYNTHASE-LIKE A2 (CSLA2; At5g22740) expression was observed in several seed tissues, including the epidermal cells of developing seed coats. Disruption of CSLA2 resulted in thinner adherent mucilage halos, although the total amount of the adherent mucilage did not change compared with the wild type. This suggested that the adherent mucilage in the mutant was more compact compared with that of the wild type. In accordance with the role of CSLA2 in glucomannan synthesis, csla2-1 mucilage contained 30% less mannosyl and glucosyl content than did the wild type. No appreciable changes in the composition, structure, or macromolecular properties were observed for nonmannan polysaccharides in mutant mucilage. Biochemical analysis revealed that cellulose crystallinity was substantially reduced in csla2-1 mucilage; this was supported by the removal of most mucilage cellulose through treatment of csla2-1 seeds with endo-β-glucanase. Mutation in CSLA2 also resulted in altered spatial distribution of cellulose and an absence of birefringent cellulose microfibrils within the adherent mucilage. As with the observed changes in crystalline cellulose, the spatial distribution of pectin was also modified in csla2-1 mucilage. Taken together, our results demonstrate that glucomannans synthesized by CSLA2 are involved in modulating the structure of adherent mucilage, potentially through altering cellulose organization and crystallization.
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64
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Saez-Aguayo S, Rondeau-Mouro C, Macquet A, Kronholm I, Ralet MC, Berger A, Sallé C, Poulain D, Granier F, Botran L, Loudet O, de Meaux J, Marion-Poll A, North HM. Local evolution of seed flotation in Arabidopsis. PLoS Genet 2014; 10:e1004221. [PMID: 24625826 PMCID: PMC3953066 DOI: 10.1371/journal.pgen.1004221] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Accepted: 01/22/2014] [Indexed: 02/02/2023] Open
Abstract
Arabidopsis seeds rapidly release hydrophilic polysaccharides from the seed coat on imbibition. These form a heavy mucilage layer around the seed that makes it sink in water. Fourteen natural Arabidopsis variants from central Asia and Scandinavia were identified with seeds that have modified mucilage release and float. Four of these have a novel mucilage phenotype with almost none of the released mucilage adhering to the seed and the absence of cellulose microfibrils. Mucilage release was modified in the variants by ten independent causal mutations in four different loci. Seven distinct mutations affected one locus, coding the MUM2 β-D-galactosidase, and represent a striking example of allelic heterogeneity. The modification of mucilage release has thus evolved a number of times independently in two restricted geographical zones. All the natural mutants identified still accumulated mucilage polysaccharides in seed coat epidermal cells. Using nuclear magnetic resonance (NMR) relaxometry their production and retention was shown to reduce water mobility into internal seed tissues during imbibition, which would help to maintain seed buoyancy. Surprisingly, despite released mucilage being an excellent hydrogel it did not increase the rate of water uptake by internal seed tissues and is more likely to play a role in retaining water around the seed.
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Affiliation(s)
- Susana Saez-Aguayo
- INRA, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France
- AgroParisTech, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France
| | - Corinne Rondeau-Mouro
- INRA, UR 1268 Biopolymères Interactions Assemblages, INRA, Nantes, France
- Irstea, UR TERE, CS 64427, Rennes, France
| | - Audrey Macquet
- INRA, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France
- AgroParisTech, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France
| | - Ilkka Kronholm
- Department of Genetics and Plant Breeding, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | | | - Adeline Berger
- INRA, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France
- AgroParisTech, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France
| | - Christine Sallé
- INRA, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France
- AgroParisTech, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France
| | - Damien Poulain
- INRA, UR 1268 Biopolymères Interactions Assemblages, INRA, Nantes, France
| | - Fabienne Granier
- INRA, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France
- AgroParisTech, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France
| | - Lucy Botran
- INRA, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France
- AgroParisTech, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France
| | - Olivier Loudet
- INRA, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France
- AgroParisTech, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France
| | - Juliette de Meaux
- Department of Genetics and Plant Breeding, Max Planck Institute for Plant Breeding Research, Cologne, Germany
- Institute of Evolution and Biodiversity, University of Münster, Münster, Germany
| | - Annie Marion-Poll
- INRA, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France
- AgroParisTech, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France
| | - Helen M. North
- INRA, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France
- AgroParisTech, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France
- * E-mail:
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65
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Wang Z, Chen M, Chen T, Xuan L, Li Z, Du X, Zhou L, Zhang G, Jiang L. TRANSPARENT TESTA2 regulates embryonic fatty acid biosynthesis by targeting FUSCA3 during the early developmental stage of Arabidopsis seeds. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2014; 77:757-69. [PMID: 24397827 DOI: 10.1111/tpj.12426] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Revised: 12/09/2013] [Accepted: 12/23/2013] [Indexed: 05/20/2023]
Abstract
TRANSPARENT TESTA2 (TT2) regulates the biosynthesis of proanthocyanidins in the seed coat of Arabidopsis. We recently found that TT2 also participates in inhibition of fatty acid (FA) biosynthesis in the seed embryo. However, the mechanism by which TT2 suppresses the accumulation of seed FA remains unclear. In this study, we show that TT2 is expressed in embryos at an early developmental stage. TT2 is directly bound to the regulatory region of FUSCA3 (FUS3), and mediates the expression of numerous genes in the FA biosynthesis pathway. These genes include BCCP2, CAC2, MOD1 and KASII, which encode proteins involved in the initial steps of FA chain formation, FAD2 and FAD3, which are responsible for FA desaturation, and FAE1, which catalyzes very-long-chain FA elongation. Loss of function of TT2 results in reduced expression of GLABRA2 but does not cause a significant reduction in the mucilage attached to the seed coats, which competes with FA for photosynthates. TT2 is expressed in both maternal seed coats and embryonic tissues, but proanthocyanidins are only found in wild-type seed coats and not in embryonic tissues. The amount of proanthocyanidins in the seed coat is negatively correlated with the amount of FAs in the embryo.
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Affiliation(s)
- Zhong Wang
- Provincial Key Laboratory of Crop Gene Resources, College of Agriculture and Biotechnology, Zhejiang University, 866 Yu-Hang-Tang Road, Hangzhou, 310058, China
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66
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Kong Y, Zhou G, Abdeen AA, Schafhauser J, Richardson B, Atmodjo MA, Jung J, Wicker L, Mohnen D, Western T, Hahn MG. GALACTURONOSYLTRANSFERASE-LIKE5 is involved in the production of Arabidopsis seed coat mucilage. PLANT PHYSIOLOGY 2013; 163:1203-17. [PMID: 24092888 PMCID: PMC3813644 DOI: 10.1104/pp.113.227041] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Accepted: 10/02/2013] [Indexed: 05/17/2023]
Abstract
The function of a putative galacturonosyltransferase from Arabidopsis (Arabidopsis thaliana; At1g02720; GALACTURONOSYLTRANSFERASE-LIKE5 [AtGATL5]) was studied using a combination of molecular genetic, chemical, and immunological approaches. AtGATL5 is expressed in all plant tissues, with highest expression levels in siliques 7 DPA. Furthermore, its expression is positively regulated by several transcription factors that are known to regulate seed coat mucilage production. AtGATL5 is localized in both endoplasmic reticulum and Golgi, in comparison with marker proteins resident to these subcellular compartments. A transfer DNA insertion in the AtGATL5 gene generates seed coat epidermal cell defects both in mucilage synthesis and cell adhesion. Transformation of atgatl5-1 mutants with the wild-type AtGATL5 gene results in the complementation of all morphological phenotypes. Compositional analyses of the mucilage isolated from the atgatl5-1 mutant demonstrated that galacturonic acid and rhamnose contents are decreased significantly in atgatl5-1 compared with wild-type mucilage. No changes in structure were observed between soluble mucilage isolated from wild-type and mutant seeds, except that the molecular weight of the mutant mucilage increased 63% compared with that of the wild type. These data provide evidence that AtGATL5 might function in the regulation of the final size of the mucilage rhamnogalacturonan I.
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67
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Lee KJD, Cornuault V, Manfield IW, Ralet MC, Paul Knox J. Multi-scale spatial heterogeneity of pectic rhamnogalacturonan I (RG-I) structural features in tobacco seed endosperm cell walls. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 75:1018-27. [PMID: 23789903 PMCID: PMC3824205 DOI: 10.1111/tpj.12263] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Revised: 05/24/2013] [Accepted: 06/10/2013] [Indexed: 05/23/2023]
Abstract
Plant cell walls are complex configurations of polysaccharides that fulfil a diversity of roles during plant growth and development. They also provide sets of biomaterials that are widely exploited in food, fibre and fuel applications. The pectic polysaccharides, which comprise approximately a third of primary cell walls, form complex supramolecular structures with distinct glycan domains. Rhamnogalacturonan I (RG-I) is a highly structurally heterogeneous branched glycan domain within the pectic supramolecule that contains rhamnogalacturonan, arabinan and galactan as structural elements. Heterogeneous RG-I polymers are implicated in generating the mechanical properties of cell walls during cell development and plant growth, but are poorly understood in architectural, biochemical and functional terms. Using specific monoclonal antibodies to the three major RG-I structural elements (arabinan, galactan and the rhamnogalacturonan backbone) for in situ analyses and chromatographic detection analyses, the relative occurrences of RG-I structures were studied within a single tissue: the tobacco seed endosperm. The analyses indicate that the features of the RG-I polymer display spatial heterogeneity at the level of the tissue and the level of single cell walls, and also heterogeneity at the biochemical level. This work has implications for understanding RG-I glycan complexity in the context of cell-wall architectures and in relation to cell-wall functions in cell and tissue development.
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Affiliation(s)
- Kieran JD Lee
- Centre for Plant Sciences, Faculty of Biological Sciences, University of LeedsLeeds, LS2 9JT, UK
| | - Valérie Cornuault
- Centre for Plant Sciences, Faculty of Biological Sciences, University of LeedsLeeds, LS2 9JT, UK
| | - Iain W Manfield
- Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of LeedsLeeds, LS2 9JT, UK
| | - Marie-Christine Ralet
- UR1268 Biopolymères, Interactions et Assemblages, Institut National de la Recherche AgronomiqueRue de la Géraudière, BP 71627, F–44316, Nantes, France
| | - J Paul Knox
- Centre for Plant Sciences, Faculty of Biological Sciences, University of LeedsLeeds, LS2 9JT, UK
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Kunieda T, Shimada T, Kondo M, Nishimura M, Nishitani K, Hara-Nishimura I. Spatiotemporal secretion of PEROXIDASE36 is required for seed coat mucilage extrusion in Arabidopsis. THE PLANT CELL 2013; 25:1355-67. [PMID: 23572548 PMCID: PMC3663273 DOI: 10.1105/tpc.113.110072] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 03/13/2013] [Accepted: 03/21/2013] [Indexed: 05/21/2023]
Abstract
The epidermal cells of the Arabidopsis thaliana seed coat, which correspond to the second layer of the outer integument (oi2), contain large quantities of a pectic polysaccharide called mucilage within the apoplastic space beneath the outer periclinal cell wall. Immediately after seed imbibition, the mucilage is extruded and completely envelops the seed in a gel-like capsule. We found that a class III peroxidase family protein, PEROXIDASE36 (PER36), functions as a mucilage extrusion factor. Expression of PER36 occurred only in oi2 cells for a few days around the torpedo stage. A PER36-green fluorescent protein fusion was secreted into the outer cell wall in a polarized manner. per36 mutants were defective in mucilage extrusion after seed imbibition due to the failure of outer cell wall rupture, although the mutants exhibited normal monosaccharide composition of the mucilage. This abnormal phenotype of per36 was rescued by pectin solubilization, which promoted cell wall loosening. These results suggest that PER36 regulates the degradation of the outer cell wall. Taken together, this work indicates that polarized secretion of PER36 in a developmental stage-dependent manner plays a role in cell wall modification of oi2 cells.
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Affiliation(s)
- Tadashi Kunieda
- Department of Botany, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
- Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Tomoo Shimada
- Department of Botany, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Maki Kondo
- Department of Cell Biology, National Institute for Basic Biology, Okazaki 444-8585, Japan
| | - Mikio Nishimura
- Department of Cell Biology, National Institute for Basic Biology, Okazaki 444-8585, Japan
| | - Kazuhiko Nishitani
- Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Ikuko Hara-Nishimura
- Department of Botany, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
- Address correspondence to
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69
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Voiniciuc C, Dean GH, Griffiths JS, Kirchsteiger K, Hwang YT, Gillett A, Dow G, Western TL, Estelle M, Haughn GW. Flying saucer1 is a transmembrane RING E3 ubiquitin ligase that regulates the degree of pectin methylesterification in Arabidopsis seed mucilage. THE PLANT CELL 2013; 25:944-59. [PMID: 23482858 PMCID: PMC3634698 DOI: 10.1105/tpc.112.107888] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Revised: 02/14/2013] [Accepted: 02/18/2013] [Indexed: 05/21/2023]
Abstract
Pectins are complex polysaccharides that form the gel matrix of the primary cell wall and are abundant in the middle lamella that holds plant cells together. Their degree of methylesterification (DM) impacts wall strength and cell adhesion since unesterified pectin regions can cross-link via Ca(2+) ions to form stronger gels. Here, we characterize flying saucer1 (fly1), a novel Arabidopsis thaliana seed coat mutant, which displays primary wall detachment, reduced mucilage extrusion, and increased mucilage adherence. These defects appear to result from a lower DM in mucilage and are enhanced by the addition of Ca(2+) or completely rescued using alkaline Ca(2+) chelators. FLY1 encodes a transmembrane protein with a RING-H2 domain that has in vitro E3 ubiquitin ligase activity. FLY1 is orthologous to TRANSMEMBRANE UBIQUITIN LIGASE1, a Golgi-localized E3 ligase involved in the quality control of membrane proteins in yeast. However, FLY1-yellow fluorescent protein (YFP) fusions are localized in punctae that are predominantly distinct from the Golgi and the trans-Golgi network/early endosome in the seed coat epidermis. Wortmannin treatment, which induces the fusion of late endosomes in plants, resulted in enlarged FLY1-YFP bodies. We propose that FLY1 regulates the DM of pectin in mucilage, potentially by recycling pectin methylesterase enzymes in the endomembrane system of seed coat epidermal cells.
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Affiliation(s)
- Cătălin Voiniciuc
- Department of Botany, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Gillian H. Dean
- Department of Botany, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Jonathan S. Griffiths
- Department of Botany, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Kerstin Kirchsteiger
- Section of Cell and Developmental Biology, University of California, La Jolla, California 92093
| | - Yeen Ting Hwang
- Department of Botany, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Alan Gillett
- Department of Botany, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Graham Dow
- Department of Botany, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Tamara L. Western
- Department of Botany, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Mark Estelle
- Section of Cell and Developmental Biology, University of California, La Jolla, California 92093
| | - George W. Haughn
- Department of Botany, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Address correspondence to
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Saez-Aguayo S, Ralet MC, Berger A, Botran L, Ropartz D, Marion-Poll A, North HM. PECTIN METHYLESTERASE INHIBITOR6 promotes Arabidopsis mucilage release by limiting methylesterification of homogalacturonan in seed coat epidermal cells. THE PLANT CELL 2013; 25:308-23. [PMID: 23362209 PMCID: PMC3584544 DOI: 10.1105/tpc.112.106575] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Revised: 12/20/2012] [Accepted: 01/03/2013] [Indexed: 05/17/2023]
Abstract
Imbibed seeds of the Arabidopsis thaliana accession Djarly are affected in mucilage release from seed coat epidermal cells. The impaired locus was identified as a pectin methylesterase inhibitor gene, PECTIN METHYLESTERASE INHIBITOR6 (PMEI6), specifically expressed in seed coat epidermal cells at the time when mucilage polysaccharides are accumulated. This spatio-temporal regulation appears to be modulated by GLABRA2 and LEUNIG HOMOLOG/MUCILAGE MODIFIED1, as expression of PMEI6 is reduced in mutants of these transcription regulators. In pmei6, mucilage release was delayed and outer cell walls of epidermal cells did not fragment. Pectin methylesterases (PMEs) demethylate homogalacturonan (HG), and the majority of HG found in wild-type mucilage was in fact derived from outer cell wall fragments. This correlated with the absence of methylesterified HG labeling in pmei6, whereas transgenic plants expressing the PMEI6 coding sequence under the control of the 35S promoter had increased labeling of cell wall fragments. Activity tests on seeds from pmei6 and 35S:PMEI6 transgenic plants showed that PMEI6 inhibits endogenous PME activities, in agreement with reduced overall methylesterification of mucilage fractions and demucilaged seeds. Another regulator of PME activity in seed coat epidermal cells, the subtilisin-like Ser protease SBT1.7, acts on different PMEs, as a pmei6 sbt1.7 mutant showed an additive phenotype.
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Affiliation(s)
- Susana Saez-Aguayo
- Institut National de la Recherche Agronomique, Institut Jean-Pierre Bourgin, Unité Mixte de Recherche 1318, Saclay Plant Sciences, F-78026 Versailles, France
- AgroParisTech, Institut Jean-Pierre Bourgin, Unité Mixte de Recherche 1318, Saclay Plant Sciences, F-78026 Versailles, France
| | - Marie-Christine Ralet
- Institut National de la Recherche Agronomique, Unité de Recherche 1268 Biopolymères Interactions Assemblages, F-44316 Nantes, France
| | - Adeline Berger
- Institut National de la Recherche Agronomique, Institut Jean-Pierre Bourgin, Unité Mixte de Recherche 1318, Saclay Plant Sciences, F-78026 Versailles, France
- AgroParisTech, Institut Jean-Pierre Bourgin, Unité Mixte de Recherche 1318, Saclay Plant Sciences, F-78026 Versailles, France
| | - Lucy Botran
- Institut National de la Recherche Agronomique, Institut Jean-Pierre Bourgin, Unité Mixte de Recherche 1318, Saclay Plant Sciences, F-78026 Versailles, France
- AgroParisTech, Institut Jean-Pierre Bourgin, Unité Mixte de Recherche 1318, Saclay Plant Sciences, F-78026 Versailles, France
| | - David Ropartz
- Institut National de la Recherche Agronomique, Unité de Recherche 1268 Biopolymères Interactions Assemblages, F-44316 Nantes, France
| | - Annie Marion-Poll
- Institut National de la Recherche Agronomique, Institut Jean-Pierre Bourgin, Unité Mixte de Recherche 1318, Saclay Plant Sciences, F-78026 Versailles, France
- AgroParisTech, Institut Jean-Pierre Bourgin, Unité Mixte de Recherche 1318, Saclay Plant Sciences, F-78026 Versailles, France
| | - Helen M. North
- Institut National de la Recherche Agronomique, Institut Jean-Pierre Bourgin, Unité Mixte de Recherche 1318, Saclay Plant Sciences, F-78026 Versailles, France
- AgroParisTech, Institut Jean-Pierre Bourgin, Unité Mixte de Recherche 1318, Saclay Plant Sciences, F-78026 Versailles, France
- Address correspondence to
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71
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Abstract
Recent progress in the identification and characterization of pectin biosynthetic proteins and the discovery of pectin domain-containing proteoglycans are changing our view of how pectin, the most complex family of plant cell wall polysaccharides, is synthesized. The functional confirmation of four types of pectin biosynthetic glycosyltransferases, the identification of multiple putative pectin glycosyl- and methyltransferases, and the characteristics of the GAUT1:GAUT7 homogalacturonan biosynthetic complex with its novel mechanism for retaining catalytic subunits in the Golgi apparatus and its 12 putative interacting proteins are beginning to provide a framework for the pectin biosynthetic process. We propose two partially overlapping hypothetical and testable models for pectin synthesis: the consecutive glycosyltransferase model and the domain synthesis model.
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Affiliation(s)
- Melani A Atmodjo
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602-4712, USA.
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73
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Angeles-Núñez JG, Tiessen A. Regulation of AtSUS2 and AtSUS3 by glucose and the transcription factor LEC2 in different tissues and at different stages of Arabidopsis seed development. PLANT MOLECULAR BIOLOGY 2012; 78:377-92. [PMID: 22228409 DOI: 10.1007/s11103-011-9871-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Accepted: 12/14/2011] [Indexed: 05/25/2023]
Abstract
Sucrose synthase (SUS) is a key enzyme of carbon metabolism in heterotrophic tissues of plants. The Arabidopsis genome contains six SUS genes. Two members of this family, namely AtSUS2 (At5g49190) and AtSUS3 (At4g02280) are strongly and differentially expressed in Arabidopsis seed. Expression analysis was carried out using SUS:promoter-GUS fusion lines in a wild-type genetic background or in a mutant carrying a lesion in the transcription factor LEAFY COTYLEDON 2 (LEC2; At1g28300). The accumulation patterns of mRNA, protein, and SUS activity were altered in the lec2 mutant during seed development 9-18 days after flowering. This indicates that LEC2 acts epistatically on the expression of AtSUS2 and AtSUS3. It appears that LEC2 is required for cotyledon-specific expression of both SUS genes but it is not responsible for expression in the radicle tip during embryo development. The AtSUS2 promoter was induced in planta by feeding of glucose but less so by sucrose and trehalose. Non-phosphorylable glucose analogs such as 3-O-methyl-glucose and 2-deoxyglucose also caused an induction, suggesting that sugar signaling proceeds by a hexokinase-independent pathway, possibly involving hexose sensing. Analysis of transgenic lines carrying of truncated versions of the AtSUS2:promoter fused to Beta-glucuronidase activity revealed an internal 421 bp region that was responsible for expression in seeds. Bioinformatic sequence analysis revealed regulatory cis-elements putatively responsible for the spatio-temporal pattern of AtSUS2 expression such as the SEF3 (aaccca) and W-box (ttgact) motifs. These findings are discussed in relation to the roles played by AtSUS2, AtSUS3 and LEC2 in the biosynthesis of seed storage products in Arabidopsis.
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Affiliation(s)
- Juan Gabriel Angeles-Núñez
- Departamento de Ingeniería Genética, CINVESTAV, Unidad Irapuato, Km 9.8 Libramiento Norte, CP 36821 Irapuato, Guanajuato, Mexico
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74
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Moreau M, Azzopardi M, Clément G, Dobrenel T, Marchive C, Renne C, Martin-Magniette ML, Taconnat L, Renou JP, Robaglia C, Meyer C. Mutations in the Arabidopsis homolog of LST8/GβL, a partner of the target of Rapamycin kinase, impair plant growth, flowering, and metabolic adaptation to long days. THE PLANT CELL 2012; 24:463-81. [PMID: 22307851 PMCID: PMC3315227 DOI: 10.1105/tpc.111.091306] [Citation(s) in RCA: 170] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2011] [Revised: 01/04/2012] [Accepted: 01/15/2012] [Indexed: 05/19/2023]
Abstract
The conserved Target of Rapamycin (TOR) kinase forms high molecular mass complexes and is a major regulator of cellular adaptations to environmental cues. The Lethal with Sec Thirteen 8/G protein β subunit-like (LST8/GβL) protein is a member of the TOR complexes, and two putative LST8 genes are present in Arabidopsis thaliana, of which only one (LST8-1) is significantly expressed. The Arabidopsis LST8-1 protein is able to complement yeast lst8 mutations and interacts with the TOR kinase. Mutations in the LST8-1 gene resulted in reduced vegetative growth and apical dominance with abnormal development of flowers. Mutant plants were also highly sensitive to long days and accumulated, like TOR RNA interference lines, higher amounts of starch and amino acids, including proline and glutamine, while showing reduced concentrations of inositol and raffinose. Accordingly, transcriptomic and enzymatic analyses revealed a higher expression of genes involved in nitrate assimilation when lst8-1 mutants were shifted to long days. The transcriptome of lst8-1 mutants in long days was found to share similarities with that of a myo-inositol 1 phosphate synthase mutant that is also sensitive to the extension of the light period. It thus appears that the LST8-1 protein has an important role in regulating amino acid accumulation and the synthesis of myo-inositol and raffinose during plant adaptation to long days.
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Affiliation(s)
- Manon Moreau
- Institut Jean-Pierre Bourgin, Unité Mixte de Recherche 1318, Institut National de la Recherche Agronomique AgroParisTech, 78026 Versailles cedex, France
- Laboratoire de Génétique et Biophysique des Plantes, Unité Mixte de Recherche 7225, Commissariat à l'Energie Atomique–Institut de Biologie Environnementale et Biotechnologie–Service de Biologie Végétale et de Microbiologie Environnementales, Centre National de la Recherche Scientifique, Université Aix Marseille, Faculté des Sciences de Luminy, 13009 Marseille, France
| | - Marianne Azzopardi
- Institut Jean-Pierre Bourgin, Unité Mixte de Recherche 1318, Institut National de la Recherche Agronomique AgroParisTech, 78026 Versailles cedex, France
| | - Gilles Clément
- Institut Jean-Pierre Bourgin, Unité Mixte de Recherche 1318, Institut National de la Recherche Agronomique AgroParisTech, 78026 Versailles cedex, France
| | - Thomas Dobrenel
- Institut Jean-Pierre Bourgin, Unité Mixte de Recherche 1318, Institut National de la Recherche Agronomique AgroParisTech, 78026 Versailles cedex, France
| | - Chloé Marchive
- Institut Jean-Pierre Bourgin, Unité Mixte de Recherche 1318, Institut National de la Recherche Agronomique AgroParisTech, 78026 Versailles cedex, France
| | - Charlotte Renne
- Institut Jean-Pierre Bourgin, Unité Mixte de Recherche 1318, Institut National de la Recherche Agronomique AgroParisTech, 78026 Versailles cedex, France
| | - Marie-Laure Martin-Magniette
- Unité Mixte de Recherche 518, Institut National de la Recherche Agronomique AgroParisTech, 75005 Paris, France
- Unité de Recherche en Génomique Végétale, Unité Mixte de Recherche 1165, Institut National de la Recherche Agronomique, Université Evry Val d'Essonne, Centre National de la Recherche Scientifique, 91057 Evry cedex, France
| | - Ludivine Taconnat
- Unité de Recherche en Génomique Végétale, Unité Mixte de Recherche 1165, Institut National de la Recherche Agronomique, Université Evry Val d'Essonne, Centre National de la Recherche Scientifique, 91057 Evry cedex, France
| | - Jean-Pierre Renou
- Unité de Recherche en Génomique Végétale, Unité Mixte de Recherche 1165, Institut National de la Recherche Agronomique, Université Evry Val d'Essonne, Centre National de la Recherche Scientifique, 91057 Evry cedex, France
| | - Christophe Robaglia
- Laboratoire de Génétique et Biophysique des Plantes, Unité Mixte de Recherche 7225, Commissariat à l'Energie Atomique–Institut de Biologie Environnementale et Biotechnologie–Service de Biologie Végétale et de Microbiologie Environnementales, Centre National de la Recherche Scientifique, Université Aix Marseille, Faculté des Sciences de Luminy, 13009 Marseille, France
| | - Christian Meyer
- Institut Jean-Pierre Bourgin, Unité Mixte de Recherche 1318, Institut National de la Recherche Agronomique AgroParisTech, 78026 Versailles cedex, France
- Address correspondence to
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75
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Joosen RVL, Arends D, Willems LAJ, Ligterink W, Jansen RC, Hilhorst HW. Visualizing the genetic landscape of Arabidopsis seed performance. PLANT PHYSIOLOGY 2012; 158:570-89. [PMID: 22158761 PMCID: PMC3271751 DOI: 10.1104/pp.111.186676] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2011] [Accepted: 12/11/2011] [Indexed: 05/18/2023]
Abstract
Perfect timing of germination is required to encounter optimal conditions for plant survival and is the result of a complex interaction between molecular processes, seed characteristics, and environmental cues. To detangle these processes, we made use of natural genetic variation present in an Arabidopsis (Arabidopsis thaliana) Bayreuth × Shahdara recombinant inbred line population. For a detailed analysis of the germination response, we characterized rate, uniformity, and maximum germination and discuss the added value of such precise measurements. The effects of after-ripening, stratification, and controlled deterioration as well as the effects of salt, mannitol, heat, cold, and abscisic acid (ABA) with and without cold stratification were analyzed for these germination characteristics. Seed morphology (size and length) of both dry and imbibed seeds was quantified by using image analysis. For the overwhelming amount of data produced in this study, we developed new approaches to perform and visualize high-throughput quantitative trait locus (QTL) analysis. We show correlation of trait data, (shared) QTL positions, and epistatic interactions. The detection of similar loci for different stresses indicates that, often, the molecular processes regulating environmental responses converge into similar pathways. Seven major QTL hotspots were confirmed using a heterogeneous inbred family approach. QTLs colocating with previously reported QTLs and well-characterized mutants are discussed. A new connection between dormancy, ABA, and a cripple mucilage formation due to a naturally occurring mutation in the MUCILAGE-MODIFIED2 gene is proposed, and this is an interesting lead for further research on the regulatory role of ABA in mucilage production and its multiple effects on germination parameters.
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76
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Mikshina PV, Gurjanov OP, Mukhitova FK, Petrova AA, Shashkov AS, Gorshkova TA. Structural details of pectic galactan from the secondary cell walls of flax (Linum usitatissimum L.) phloem fibres. Carbohydr Polym 2012; 87:853-861. [DOI: 10.1016/j.carbpol.2011.08.068] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Revised: 08/19/2011] [Accepted: 08/24/2011] [Indexed: 10/17/2022]
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Haughn GW, Western TL. Arabidopsis Seed Coat Mucilage is a Specialized Cell Wall that Can be Used as a Model for Genetic Analysis of Plant Cell Wall Structure and Function. FRONTIERS IN PLANT SCIENCE 2012; 3:64. [PMID: 22645594 PMCID: PMC3355795 DOI: 10.3389/fpls.2012.00064] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2012] [Accepted: 03/16/2012] [Indexed: 05/17/2023]
Abstract
Arabidopsis seed coat epidermal cells produce a large quantity of mucilage that is extruded upon exposure to water. Chemical analyses and cell biological techniques suggest that this mucilage represents a specialized type of secondary cell wall composed primarily of pectin with lesser amounts of cellulose and xyloglucan. Once extruded, the mucilage capsule has a distinctive structure with an outer non-adherent layer that is easily removed by shaking in water, and an inner adherent layer that can only be removed with strong acid or base. Most of the cellulose in the mucilage is present in the inner layer and is responsible at least in part for its adherence to the seed. There are also differences in the pectin composition between the two layers that could contribute to the difference in adherence. The Arabidopsis seed coat epidermis and its mucilage are not essential for seed viability or germination. This dispensability, combined with the fact that the epidermal cells synthesize an accessible pectin-rich cell wall at a specific time in development, makes them well suited as a genetic model for studying cell wall biogenesis, function, and regulation. Mutants defective in seed mucilage identified by both forward and reverse genetic analyses are proving useful in establishing connections between carbohydrate structure and cell wall properties in vivo. In the future, genetic engineering of seed coat mucilage carbohydrates should prove useful for testing hypotheses concerning cell wall structure and function.
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Affiliation(s)
- George W. Haughn
- Department of Botany, University of British ColumbiaVancouver, BC, Canada
- *Correspondence: George W. Haughn, Department of Botany, University of British Columbia, 6270 University Boulevard, Vancouver, BC, Canada V6T 1Z4. e-mail:
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78
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Lee JE, Golz JF. Diverse roles of Groucho/Tup1 co-repressors in plant growth and development. PLANT SIGNALING & BEHAVIOR 2012; 7:86-92. [PMID: 22301974 PMCID: PMC3357377 DOI: 10.4161/psb.7.1.18377] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Transcriptional regulation involves coordinated and often complex interactions between activators and repressors that together dictate the temporal and spatial activity of target genes. While the study of developmental regulation has often focused on positively acting transcription factors, it is becoming increasingly clear that transcriptional repression is a key regulatory mechanism underpinning many developmental processes in both plants and animals. In this review, we focus on the plant Groucho (Gro)/Tup1-like co-repressors and discuss their roles in establishing the apical-basal axis of the developing embryo, maintaining the stem cell population in the shoot apex and determining floral organ identity. As well as being developmental regulators, recent studies have shown that these co-repressors play a central role in regulating auxin and jasmonate signalling pathways and are also linked to the regulation of pectin structure in the seed coat. These latest findings point to the Gro/Tup1-like co-repressors playing a much broad role in plant growth and development than previously thought; an observation that underlines the central importance of transcriptional repression in plant gene regulation.
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79
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Abstract
Plant cell walls have the remarkable property of combining extreme tensile strength with extensibility. The maintenance of such an exoskeleton creates nontrivial challenges for the plant cell: How can it control cell wall assembly and remodeling during growth while maintaining mechanical integrity? How can it deal with cell wall damage inflicted by herbivores, pathogens, or abiotic stresses? These processes likely require mechanisms to keep the cell informed about the status of the cell wall. In yeast, a cell wall integrity (CWI) signaling pathway has been described in great detail; in plants, the existence of CWI signaling has been demonstrated, but little is known about the signaling pathways involved. In this review, we first describe cell wall-related processes that may require or can be targets of CWI signaling and then discuss our current understanding of CWI signaling pathways and future prospects in this emerging field of plant biology.
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Affiliation(s)
- Sebastian Wolf
- Institut Jean-Pierre Bourgin, UMR 1318 INRA/AgroParisTech, Versailles Cedex, France.
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80
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Dean G, Cao Y, Xiang D, Provart NJ, Ramsay L, Ahad A, White R, Selvaraj G, Datla R, Haughn G. Analysis of gene expression patterns during seed coat development in Arabidopsis. MOLECULAR PLANT 2011; 4:1074-91. [PMID: 21653281 DOI: 10.1093/mp/ssr040] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The seed coat is important for embryo protection, seed hydration, and dispersal. Seed coat composition is also of interest to the agricultural sector, since it impacts the nutritional value for humans and livestock alike. Although some seed coat genes have been identified, the developmental pathways controlling seed coat development are not completely elucidated, and a global genetic program associated with seed coat development has not been reported. This study uses a combination of genetic and genomic approaches in Arabidopsis thaliana to begin to address these knowledge gaps. Seed coat development is a complex process whereby the integuments of the ovule differentiate into specialized cell types. In Arabidopsis, the outermost layer of cells secretes mucilage into the apoplast and develops a secondary cell wall known as a columella. The layer beneath the epidermis, the palisade, synthesizes a secondary cell wall on its inner tangential side. The innermost layer (the pigmented layer or endothelium) produces proanthocyanidins that condense into tannins and oxidize, giving a brown color to mature seeds. Genetic separation of these cell layers was achieved using the ap2-7 and tt16-1 mutants, where the epidermis/palisade and the endothelium do not develop respectively. This genetic ablation was exploited to examine the developmental programs of these cell types by isolating and collecting seed coats at key transitions during development and performing global gene expression analysis. The data indicate that the developmental programs of the epidermis and the pigmented layer proceed relatively independently. Global expression datasets that can be used for identification of new gene candidates for seed coat development were generated. These dataset provide a comprehensive expression profile for developing seed coats in Arabidopsis, and should provide a useful resource and reference for other seed systems.
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Affiliation(s)
- Gillian Dean
- Department of Botany, University of British Columbia, 6270 University Blvd, Vancouver, BC, V6T 1Z4, Canada
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81
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Yapo BM. Rhamnogalacturonan-I: A Structurally Puzzling and Functionally Versatile Polysaccharide from Plant Cell Walls and Mucilages. POLYM REV 2011. [DOI: 10.1080/15583724.2011.615962] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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82
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Mendu V, Griffiths JS, Persson S, Stork J, Downie AB, Voiniciuc C, Haughn GW, DeBolt S. Subfunctionalization of cellulose synthases in seed coat epidermal cells mediates secondary radial wall synthesis and mucilage attachment. PLANT PHYSIOLOGY 2011; 157:441-53. [PMID: 21750228 PMCID: PMC3165890 DOI: 10.1104/pp.111.179069] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Accepted: 07/06/2011] [Indexed: 05/17/2023]
Abstract
Arabidopsis (Arabidopsis thaliana) epidermal seed coat cells follow a complex developmental program where, following fertilization, cells of the ovule outer integument differentiate into a unique cell type. Two hallmarks of these cells are the production of a doughnut-shaped apoplastic pocket filled with pectinaceous mucilage and the columella, a thick secondary cell wall. Cellulose is thought to be a key component of both these secondary cell wall processes. Here, we investigated the role of cellulose synthase (CESA) subunits CESA2, CESA5, and CESA9 in the seed coat epidermis. We characterized the roles of these CESA proteins in the seed coat by analyzing cell wall composition and morphology in cesa mutant lines. Mutations in any one of these three genes resulted in lower cellulose content, a loss of cell shape uniformity, and reduced radial wall integrity. In addition, we found that attachment of the mucilage halo to the parent seed following extrusion is maintained by cellulose-based connections requiring CESA5. Hence, we show that cellulose fulfills an adhesion role between the extracellular mucilage matrix and the parent cell in seed coat epidermal cells. We propose that mucilage remains attached to the seed coat through interactions between components in the seed mucilage and cellulose. Our data suggest that CESA2 and CESA9 serve in radial wall reinforcement, as does CESA5, but CESA5 also functions in mucilage biosynthesis. These data suggest unique roles for different CESA subunits in one cell type and illustrate a complex role for cellulose biosynthesis in plant developmental biology.
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83
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Sullivan S, Ralet MC, Berger A, Diatloff E, Bischoff V, Gonneau M, Marion-Poll A, North HM. CESA5 is required for the synthesis of cellulose with a role in structuring the adherent mucilage of Arabidopsis seeds. PLANT PHYSIOLOGY 2011; 156:1725-39. [PMID: 21705653 PMCID: PMC3149949 DOI: 10.1104/pp.111.179077] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Accepted: 06/22/2011] [Indexed: 05/17/2023]
Abstract
Imbibed Arabidopsis (Arabidopsis thaliana) seeds are encapsulated by mucilage that is formed of hydrated polysaccharides released from seed coat epidermal cells. The mucilage is structured with water-soluble and adherent layers, with cellulose present uniquely in an inner domain of the latter. Using a reverse-genetic approach to identify the cellulose synthases (CESAs) that produce mucilage cellulose, cesa5 mutants were shown to be required for the correct formation of these layers. Expression of CESA5 in the seed coat was specific to epidermal cells and coincided with the accumulation of mucilage polysaccharides in their apoplast. Analysis of sugar composition showed that although total sugar composition or amounts were unchanged, their partition between layers was different in the mutant, with redistribution from adherent to water-soluble mucilage. The macromolecular characteristics of the water-soluble mucilage were also modified. In accordance with a role for CESA5 in mucilage cellulose synthesis, crystalline cellulose contents were reduced in mutant seeds and birefringent microfibrils were absent from adherent mucilage. Although the mucilage-modified5 mutant showed similar defects to cesa5 in the distribution of sugar components between water-soluble and adherent mucilage, labeling of residual adherent mucilage indicated that cesa5 contained less cellulose and less pectin methyl esterification. Together, the results demonstrate that CESA5 plays a major and essential role in cellulose production in seed mucilage, which is critical for the establishment of mucilage structured in layers and domains.
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84
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Huang J, DeBowles D, Esfandiari E, Dean G, Carpita NC, Haughn GW. The Arabidopsis transcription factor LUH/MUM1 is required for extrusion of seed coat mucilage. PLANT PHYSIOLOGY 2011; 156:491-502. [PMID: 21518777 PMCID: PMC3177253 DOI: 10.1104/pp.111.172023] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Accepted: 04/19/2011] [Indexed: 05/17/2023]
Abstract
During differentiation, the Arabidopsis (Arabidopsis thaliana) seed coat epidermal cells secrete mucilage composed primarily of rhamnogalacturonan I that is extruded from the seed coat upon imbibition. The mucilage of the mucilage modified1 (mum1) mutant contains rhamnogalacturonan I that is more highly branched and lacks the ability to be extruded when exposed to water. Our cloning of the MUM1 gene shows that it encodes a putative transcription factor, LEUNIG_HOMOLOG (LUH). Cellular localization and transcriptional assay results suggest that LUH/MUM1 is a nucleus-localized transcriptional activator. LUH/MUM1 is expressed in all the tissues examined, including the seed coat. Quantitative reverse transcription-polymerase chain reaction data suggest that LUH/MUM1 is expressed throughout seed coat development, reaching peak expression late in differentiation. LUH1/MUM1 expression in plants homozygous for mutations in several genes encoding regulators of seed coat mucilage was unchanged. Thus, LUH/MUM1 expression appears to be independent of other transcription factors known to regulate aspects of seed coat mucilage biology. The expression in the luh/mum1 mutant of three genes encoding enzymes needed for mucilage extrusion, MUM2, SUBSILIN PROTEASE1.7, and β-XYLOSIDASE1, was reduced relative to that of the wild type. Overexpression of MUM2 could partially rescue the mum1 phenotype. These data suggest that LUH/MUM1 is a positive regulator of all three genes.
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85
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Plessis A, Cournol R, Effroy D, Silva Pérez V, Botran L, Kraepiel Y, Frey A, Sotta B, Cornic G, Leung J, Giraudat J, Marion-Poll A, North HM. New ABA-hypersensitive Arabidopsis mutants are affected in loci mediating responses to water deficit and Dickeya dadantii infection. PLoS One 2011; 6:e20243. [PMID: 21633512 PMCID: PMC3102102 DOI: 10.1371/journal.pone.0020243] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2011] [Accepted: 04/27/2011] [Indexed: 01/25/2023] Open
Abstract
On water deficit, abscisic acid (ABA) induces stomata closure to reduce water loss by transpiration. To identify Arabidopsis thaliana mutants which transpire less on drought, infrared thermal imaging of leaf temperature has been used to screen for suppressors of an ABA-deficient mutant (aba3-1) cold-leaf phenotype. Three novel mutants, called hot ABA-deficiency suppressor (has), have been identified with hot-leaf phenotypes in the absence of the aba3 mutation. The defective genes imparted no apparent modification to ABA production on water deficit, were inherited recessively and enhanced ABA responses indicating that the proteins encoded are negative regulators of ABA signalling. All three mutants showed ABA-hypersensitive stomata closure and inhibition of root elongation with little modification of growth and development in non-stressed conditions. The has2 mutant also exhibited increased germination inhibition by ABA, while ABA-inducible gene expression was not modified on dehydration, indicating the mutated gene affects early ABA-signalling responses that do not modify transcript levels. In contrast, weak ABA-hypersensitivity relative to mutant developmental phenotypes suggests that HAS3 regulates drought responses by both ABA-dependent and independent pathways. has1 mutant phenotypes were only apparent on stress or ABA treatments, and included reduced water loss on rapid dehydration. The HAS1 locus thus has the required characteristics for a targeted approach to improving resistance to water deficit. In contrast to has2, has1 exhibited only minor changes in susceptibility to Dickeya dadantii despite similar ABA-hypersensitivity, indicating that crosstalk between ABA responses to this pathogen and drought stress can occur through more than one point in the signalling pathway.
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Affiliation(s)
- Anne Plessis
- Institut Jean-Pierre Bourgin, UMR1318, INRA, AgroParisTech, Versailles, France
| | - Raphaël Cournol
- Institut Jean-Pierre Bourgin, UMR1318, INRA, AgroParisTech, Versailles, France
| | - Delphine Effroy
- Institut Jean-Pierre Bourgin, UMR1318, INRA, AgroParisTech, Versailles, France
| | | | - Lucy Botran
- Institut Jean-Pierre Bourgin, UMR1318, INRA, AgroParisTech, Versailles, France
| | - Yvan Kraepiel
- Laboratoire des Interactions Plantes-Pathogènes, UMR217, AgroParisTech, INRA, UPMC Université Paris 6, Paris, France
| | - Anne Frey
- Institut Jean-Pierre Bourgin, UMR1318, INRA, AgroParisTech, Versailles, France
| | - Bruno Sotta
- Laboratoire de Physiologie Cellulaire et Moléculaire des Plantes UR5, UPMC Université Paris 6, Paris, France
| | - Gabriel Cornic
- Laboratoire d'Ecologie, Systématique et Evolution, UMR8079 IFR 87, Université Paris-Sud, CNRS, Orsay, France
| | - Jeffrey Leung
- Institut des Sciences du Végétal, UPR2355, CNRS, Gif-sur-Yvette, France
| | - Jérôme Giraudat
- Institut des Sciences du Végétal, UPR2355, CNRS, Gif-sur-Yvette, France
| | - Annie Marion-Poll
- Institut Jean-Pierre Bourgin, UMR1318, INRA, AgroParisTech, Versailles, France
| | - Helen M. North
- Institut Jean-Pierre Bourgin, UMR1318, INRA, AgroParisTech, Versailles, France
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86
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Bui M, Lim N, Sijacic P, Liu Z. LEUNIG_HOMOLOG and LEUNIG regulate seed mucilage extrusion in Arabidopsis. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2011; 53:399-408. [PMID: 21362134 DOI: 10.1111/j.1744-7909.2011.01036.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
LEUNIG (LUG) and LEUNIG_HOMOLOG (LUH) encode two closely related Arabidopsis proteins, belonging to the Gro/TLE family of transcriptional co-repressors. These two genes were previously shown to exhibit partially overlapping functions in embryo and flower development. In this report, the role of both LUH and LUG on seed mucilage extrusion was examined. Seed mucilage extrusion occurs after the seeds are imbibed, serving as functional aid in seed hydration, germination, and dispersal. While luh-1 mutants exhibited strong defects in seed mucilage extrusion, lug-3 mutants exhibited a minor phenotype in mucilage extrusion. Further characterization indicates that luh-1 does not exhibit any obvious defect in seed epidermal cell differentiation, mucilage synthesis, or mucilage deposition, suggesting a specific role of LUH in mucilage extrusion. This seed mucilage phenotype of luh-1 is identical to that of mucilage modified 2 (mum2) mutants. MUM2 encodes a β-galactosidase required for the modification of the mucilage. Quantitative reverse transcription polymerase chain reaction of RNA extracted from siliques detected a slight decrease of MUM2 mRNA in the luh-1 mutant compared to the wild type. Together, LUH and possibly LUG may specifically regulate mucilage extrusion by promoting the expression of genes required for mucilage maturation.
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Affiliation(s)
- Minh Bui
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742, USA
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87
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Walker M, Tehseen M, Doblin MS, Pettolino FA, Wilson SM, Bacic A, Golz JF. The transcriptional regulator LEUNIG_HOMOLOG regulates mucilage release from the Arabidopsis testa. PLANT PHYSIOLOGY 2011; 156:46-60. [PMID: 21402796 PMCID: PMC3091065 DOI: 10.1104/pp.111.172692] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2011] [Accepted: 03/12/2011] [Indexed: 05/17/2023]
Abstract
Exposure of the mature Arabidopsis (Arabidopsis thaliana) seed to water results in the rapid release of pectinaceous mucilage from the outer cells of the testa. Once released, mucilage completely envelops the seed in a gel-like capsule. The physical force required to rupture the outer cell wall of the testa comes from the swelling of the mucilage as it expands rapidly following hydration. In this study, we show that mutations in the transcriptional regulator LEUNIG_HOMOLOG (LUH) cause a mucilage extrusion defect due to altered mucilage swelling. Based on sugar linkage and immunomicroscopic analyses, we show that the structure of luh mucilage is altered, having both an increase in substituted rhamnogalacturonan I and in methyl-esterified homogalacturonan. Also correlated with the structural modification of luh mucilage is a significant decrease in MUCILAGE MODIFIED2 (MUM2; a β-galactosidase) expression in the luh seed coat, raising the possibility that reduced activity of this glycosidase is directly responsible for the luh mucilage defects. Consistent with this is the structural similarity between mum2 and luh mucilage as well as the observation that elevating MUM2 expression in luh mutants completely suppresses the mucilage extrusion defect. Suppression of the luh mutant phenotype was also observed when LEUNIG, a transcriptional corepressor closely related to LUH, was introduced in luh mutants under the control of the LUH promoter. Based on these data, we propose a new model for the regulation of pectin biosynthesis during plant growth and development.
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88
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Rautengarten C, Ebert B, Herter T, Petzold CJ, Ishii T, Mukhopadhyay A, Usadel B, Scheller HV. The interconversion of UDP-arabinopyranose and UDP-arabinofuranose is indispensable for plant development in Arabidopsis. THE PLANT CELL 2011; 23:1373-90. [PMID: 21478444 PMCID: PMC3101560 DOI: 10.1105/tpc.111.083931] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
L-Ara, an important constituent of plant cell walls, is found predominantly in the furanose rather than in the thermodynamically more stable pyranose form. Nucleotide sugar mutases have been demonstrated to interconvert UDP-Larabinopyranose (UDP-Arap) and UDP-L-arabinofuranose (UDP-Araf) in rice (Oryza sativa). These enzymes belong to a small gene family encoding the previously named Reversibly Glycosylated Proteins (RGPs). RGPs are plant-specific cytosolic proteins that tend to associate with the endomembrane system. In Arabidopsis thaliana, the RGP protein family consists of five closely related members. We characterized all five RGPs regarding their expression pattern and subcellular localizations in transgenic Arabidopsis plants. Enzymatic activity assays of recombinant proteins expressed in Escherichia coli identified three of the Arabidopsis RGP protein family members as UDP-L-Ara mutases that catalyze the formation of UDP-Araf from UDP-Arap. Coimmunoprecipitation and subsequent liquid chromatography-electrospray ionization-tandem mass spectrometry analysis revealed a distinct interaction network between RGPs in different Arabidopsis organs. Examination of cell wall polysaccharide preparations from RGP1 and RGP2 knockout mutants showed a significant reduction in total L-Ara content (12–31%) compared with wild-type plants. Concomitant downregulation of RGP1 and RGP2 expression results in plants almost completely deficient in cell wall–derived L-Ara and exhibiting severe developmental defects.
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Affiliation(s)
- Carsten Rautengarten
- Joint BioEnergy Institute, Feedstocks Division, Lawrence Berkeley National Laboratory, Emeryville, California 94608, USA
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89
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Wu L, El-Mezawy A, Shah S. A seed coat outer integument-specific promoter for Brassica napus. PLANT CELL REPORTS 2011; 30:75-80. [PMID: 21052676 DOI: 10.1007/s00299-010-0945-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2010] [Revised: 10/07/2010] [Accepted: 10/22/2010] [Indexed: 05/30/2023]
Abstract
In search for seed coat-specific promoters for canola (Brassica napus), transgenic plants carrying a 2,121 bp fragment of Arabidopsis thaliana At4g12960 promoter (AtGILTpro) fused to the uidA reporter gene (GUS) were generated. Out of 7 independent events in transgenic canola plants raised, 2 exhibited GUS activity exclusively in the outer integument of the seed coat. GUS activity in other tissues was also observed in the remaining five transformants. Therefore, the AtGILT promoter can be used as a canola seed coat outer integument-specific promoter after the generation and selection of desired transformants from several transgenic lines.
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Affiliation(s)
- Limin Wu
- Alberta Innovates-Technology Futures, PO Bag 4000, Hwy 16A & 75 St., Vegreville, AB, T9C 1T4, Canada.
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90
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Kulich I, Cole R, Drdová E, Cvrcková F, Soukup A, Fowler J, Zárský V. Arabidopsis exocyst subunits SEC8 and EXO70A1 and exocyst interactor ROH1 are involved in the localized deposition of seed coat pectin. THE NEW PHYTOLOGIST 2010; 188:615-25. [PMID: 20618910 DOI: 10.1111/j.1469-8137.2010.03372.x] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
• Polarized deposition of cell wall pectins is a key process in Arabidopsis thaliana myxospermous seed coat development. The exocyst, an octameric secretory vesicle tethering complex, has recently been shown to be involved in the regulation of cell polarity in plants. Here, we used the Arabidopsis seed coat to study the participation of the exocyst complex in polarized pectin delivery. • We characterized the amount of pectinaceous mucilage and seed coat structure in sec8 and exo70A1 exocyst mutants. Using a yeast two-hybrid screen, we identified a new interactor of the exocyst subunit Exo70A1, termed Roh1, a member of the DUF793 protein family. • T-DNA insertions in SEC8, EXO70A1 caused considerable deviations from normal seed coat development, in particular reduced pectin deposition and defects in the formation of the central columella of seed epidermal cells. A gain-of-function mutation of ROH1 also caused reduced pectin deposition. Interestingly, we observed a systematic difference in seed coat development between primary and secondary inflorescences in wild-type plants: siliques from secondary branches produced seeds with thicker seed coats. • The participation of exocyst subunits in mucilage deposition provides direct evidence for the role of the exocyst in polarized cell wall morphogenesis.
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Affiliation(s)
- Ivan Kulich
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czech Republic
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91
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Arsovski AA, Haughn GW, Western TL. Seed coat mucilage cells of Arabidopsis thaliana as a model for plant cell wall research. PLANT SIGNALING & BEHAVIOR 2010; 5:796-801. [PMID: 20505351 PMCID: PMC3014532 DOI: 10.4161/psb.5.7.11773] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Accepted: 03/10/2010] [Indexed: 05/17/2023]
Abstract
Plant cells are encased within a complex polysaccharide wall that strengthens the cell and has key roles in all aspects of plant cell growth, differentiation, and interaction with the environment. This dynamic structure is under continual modification during plant development, and its synthesis and modification require the activity of a myriad of enzymes. The mucilage secretory cells (MSCs) of the Arabidopsis thaliana seed coat provide a model for the discovery of novel genes involved in the synthesis, secretion and modification of cell wall components, particularly pectin. These cells synthesize copious amounts of pectinaceous mucilage during development and, upon hydration of the desiccated seed, the mucilage rapidly swells, bursts from the MSCs and surrounds the seed in a gelatinous capsule. Several genes affecting MSC differentiation, pectin synthesis, and mucilage release have been identified and additional genes involved in these and related processes including pectin secretion and the mechanical alteration of cell walls await to be discovered.
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92
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Jiang Y, Deyholos MK. Transcriptome analysis of secondary-wall-enriched seed coat tissues of canola (Brassica napus L.). PLANT CELL REPORTS 2010; 29:327-42. [PMID: 20145934 DOI: 10.1007/s00299-010-0824-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2009] [Revised: 01/15/2010] [Accepted: 01/18/2010] [Indexed: 05/23/2023]
Abstract
The seed coat of Brassica napus (canola, oilseed rape) is derived from ovule integuments and contains a layer of palisade cells, which have thick secondary walls. Because cellulosic walls and other indigestible components of the seed coat contribute negatively to the value of oilseeds, efforts are underway to alter seed development. To facilitate these efforts, and to better understand the biology of seed coats, we used a 90,000 element microarray to identify genes whose transcripts were expressed in developing seed coats of B. napus. After dissecting seed coats into three layers, and comparing transcript expression in the middle fraction (which contained the palisade-enriched tissue and bulk of inner integument) to transcript expression in developing hypocotyls, we identified 674 genes whose transcripts were more abundant in the middle fraction of the seed coat. Among these were well-characterized markers of seed coat identity and many genes associated with metabolism of cell wall polysaccharides, flavonoids and various cell wall proteins and transcription factors. Conversely, we identified 1,203 genes whose transcripts were more abundant in the hypocotyl tissue as compared to seed coat, including xylem-specific markers, such as XCP1 and XCP2. We validated 21 of the differentially expressed transcripts using quantitative RT-PCR. The results define a set of transcripts that are highly enriched in the developing seed coat of B. napus.
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Affiliation(s)
- Yuanqing Jiang
- Department of Biological Sciences, University of Alberta, Edmonton, T6G 2E9, Canada
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93
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Ibatullin FM, Banasiak A, Baumann MJ, Greffe L, Takahashi J, Mellerowicz EJ, Brumer H. A real-time fluorogenic assay for the visualization of glycoside hydrolase activity in planta. PLANT PHYSIOLOGY 2009; 151:1741-50. [PMID: 19783642 PMCID: PMC2785991 DOI: 10.1104/pp.109.147439] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2009] [Accepted: 09/22/2009] [Indexed: 05/20/2023]
Abstract
There currently exists a diverse array of molecular probes for the in situ localization of polysaccharides, nucleic acids, and proteins in plant cells, including reporter enzyme strategies (e.g. protein-glucuronidase fusions). In contrast, however, there is a paucity of methods for the direct analysis of endogenous glycoside hydrolases and transglycosidases responsible for cell wall remodeling. To exemplify the potential of fluorogenic resorufin glycosides to address this issue, a resorufin beta-glycoside of a xylogluco-oligosaccharide (XXXG-beta-Res) was synthesized as a specific substrate for in planta analysis of XEH activity. The resorufin aglycone is particularly distinguished for high sensitivity in muro assays due to a low pK(a) (5.8) and large extinction coefficient (epsilon 62,000 M(-1) cm(-1)), long-wavelength fluorescence (excitation 571 nm/emission 585 nm), and high quantum yield (0.74) of the corresponding anion. In vitro analyses demonstrated that XXXG-beta-Res is hydrolyzed by the archetypal plant XEH, nasturtium (Tropaeolum majus) NXG1, with classical Michaelis-Menten substrate saturation kinetics and a linear dependence on both enzyme concentration and incubation time. Further, XEH activity could be visualized in real time by observing the localized increase in fluorescence in germinating nasturtium seeds and Arabidopsis (Arabidopsis thaliana) inflorescent stems by confocal microscopy. Importantly, this new in situ XEH assay provides an essential complement to the in situ xyloglucan endotransglycosylase assay, thus allowing delineation of the disparate activities encoded by xyloglucan endotransglycosylase/hydrolase genes directly in plant tissues. The observation that XXXG-beta-Res is also hydrolyzed by diverse microbial XEHs indicates that this substrate, and resorufin glycosides in general, may find broad applicability for the analysis of wall restructuring by polysaccharide hydrolases during morphogenesis and plant-microbe interactions.
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Affiliation(s)
| | | | | | | | | | | | - Harry Brumer
- School of Biotechnology, Royal Institute of Technology (KTH), AlbaNova University Centre, SE–10691 Stockholm, Sweden (F.M.I., M.J.B., L.G., H.B.); Petersburg Nuclear Physics Institute, Russian Academy of Science, Molecular and Radiation Biology Division, Gatchina, St. Petersburg 188300, Russia (F.M.I.); Department of Forest Genetics and Plant Physiology, SLU, Umea Plant Science Centre, 90183 Umea, Sweden (A.B., J.T., E.J.M.); and Institute of Plant Biology, University of Wroclaw, 50–328 Wroclaw, Poland (A.B.)
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94
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Ralet MC, Lerouge P, Quéméner B. Mass spectrometry for pectin structure analysis. Carbohydr Res 2009; 344:1798-807. [DOI: 10.1016/j.carres.2008.08.036] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2008] [Revised: 08/27/2008] [Accepted: 08/29/2008] [Indexed: 01/01/2023]
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95
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Alonso-Blanco C, Aarts MGM, Bentsink L, Keurentjes JJB, Reymond M, Vreugdenhil D, Koornneef M. What has natural variation taught us about plant development, physiology, and adaptation? THE PLANT CELL 2009; 21:1877-96. [PMID: 19574434 PMCID: PMC2729614 DOI: 10.1105/tpc.109.068114] [Citation(s) in RCA: 288] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2009] [Revised: 06/10/2009] [Accepted: 06/11/2009] [Indexed: 05/17/2023]
Abstract
Nearly 100 genes and functional polymorphisms underlying natural variation in plant development and physiology have been identified. In crop plants, these include genes involved in domestication traits, such as those related to plant architecture, fruit and seed structure and morphology, as well as yield and quality traits improved by subsequent crop breeding. In wild plants, comparable traits have been dissected mainly in Arabidopsis thaliana. In this review, we discuss the major contributions of the analysis of natural variation to our understanding of plant development and physiology, focusing in particular on the timing of germination and flowering, plant growth and morphology, primary metabolism, and mineral accumulation. Overall, functional polymorphisms appear in all types of genes and gene regions, and they may have multiple mutational causes. However, understanding this diversity in relation to adaptation and environmental variation is a challenge for which tools are now available.
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Affiliation(s)
- Carlos Alonso-Blanco
- Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Departamento de Genética Molecular de Plantas, Cantoblanco 28049 Madrid, Spain
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96
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Arsovski AA, Popma TM, Haughn GW, Carpita NC, McCann MC, Western TL. AtBXL1 encodes a bifunctional beta-D-xylosidase/alpha-L-arabinofuranosidase required for pectic arabinan modification in Arabidopsis mucilage secretory cells. PLANT PHYSIOLOGY 2009; 150:1219-34. [PMID: 19458117 PMCID: PMC2705025 DOI: 10.1104/pp.109.138388] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2009] [Accepted: 05/14/2009] [Indexed: 05/17/2023]
Abstract
Following pollination, the epidermal cells of the Arabidopsis (Arabidopsis thaliana) ovule undergo a complex differentiation process that includes the synthesis and polar secretion of pectinaceous mucilage followed by the production of a secondary cell wall. Wetting of mature seeds leads to the rapid bursting of these mucilage secretory cells to release a hydrophilic gel that surrounds the seed and is believed to aid in seed hydration and germination. A novel mutant is identified where mucilage release is both patchy and slow and whose seeds display delayed germination. While developmental analysis of mutant seeds reveals no change in mucilage secretory cell morphology, changes in monosaccharide quantities are detected, suggesting the mucilage release defect results from altered mucilage composition. Plasmid rescue and cloning of the mutant locus revealed a T-DNA insertion in AtBXL1, which encodes a putative bifunctional beta-d-xylosidase/alpha-l-arabinofuranosidase that has been implicated as a beta-d-xylosidase acting during vascular development. Chemical and immunological analyses of mucilage extracted from bxl1 mutant seeds and antibody staining of developing seed coats reveal an increase in (1-->5)-linked arabinans, suggesting that BXL1 is acting as an alpha-l-arabinofuranosidase in the seed coat. This implication is supported by the ability to rescue mucilage release through treatment of bxl1 seeds with exogenous alpha-l-arabinofuranosidases. Together, these results suggest that trimming of rhamnogalacturonan I arabinan side chains is required for correct mucilage release and reveal a new role for BXL1 as an alpha-l-arabinofuranosidase acting in seed coat development.
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Affiliation(s)
- Andrej A Arsovski
- Biology Department, McGill University, Montreal, Quebec, Canada H3A 1B1
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97
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Peer WA, Hosein FN, Bandyopadhyay A, Makam SN, Otegui MS, Lee GJ, Blakeslee JJ, Cheng Y, Titapiwatanakun B, Yakubov B, Bangari B, Murphy AS. Mutation of the membrane-associated M1 protease APM1 results in distinct embryonic and seedling developmental defects in Arabidopsis. THE PLANT CELL 2009; 21:1693-721. [PMID: 19531600 PMCID: PMC2714933 DOI: 10.1105/tpc.108.059634] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2008] [Revised: 05/14/2009] [Accepted: 06/01/2009] [Indexed: 05/20/2023]
Abstract
Aminopeptidase M1 (APM1), a single copy gene in Arabidopsis thaliana, encodes a metallopeptidase originally identified via its affinity for, and hydrolysis of, the auxin transport inhibitor 1-naphthylphthalamic acid (NPA). Mutations in this gene result in haploinsufficiency. Loss-of-function mutants show irregular, uncoordinated cell divisions throughout embryogenesis, affecting the shape and number of cotyledons and the hypophysis, and is seedling lethal at 5 d after germination due to root growth arrest. Quiescent center and cell cycle markers show no signals in apm1-1 knockdown mutants, and the ground tissue specifiers SHORTROOT and SCARECROW are misexpressed or mislocalized. apm1 mutants have multiple, fused cotyledons and hypocotyls with enlarged epidermal cells with cell adhesion defects. apm1 alleles show defects in gravitropism and auxin transport. Gravistimulation decreases APM1 expression in auxin-accumulating root epidermal cells, and auxin treatment increases expression in the stele. On sucrose gradients, APM1 occurs in unique light membrane fractions. APM1 localizes at the margins of Golgi cisternae, plasma membrane, select multivesicular bodies, tonoplast, dense intravacuolar bodies, and maturing metaxylem cells. APM1 associates with brefeldin A-sensitive endomembrane structures and the plasma membrane in cortical and epidermal cells. The auxin-related phenotypes and mislocalization of auxin efflux proteins in apm1 are consistent with biochemical interactions between APM1 and NPA.
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Affiliation(s)
- Wendy Ann Peer
- Department of Horticulture, Purdue University, West Lafayette, Indiana 47907, USA
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98
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Arsovski AA, Villota MM, Rowland O, Subramaniam R, Western TL. MUM ENHANCERS are important for seed coat mucilage production and mucilage secretory cell differentiation in Arabidopsis thaliana. JOURNAL OF EXPERIMENTAL BOTANY 2009; 60:2601-12. [PMID: 19401413 PMCID: PMC2692007 DOI: 10.1093/jxb/erp102] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2008] [Revised: 02/20/2009] [Accepted: 03/11/2009] [Indexed: 05/17/2023]
Abstract
Pollination triggers not only embryo development but also the differentiation of the ovule integuments to form a specialized seed coat. The mucilage secretory cells of the Arabidopsis thaliana seed coat undergo a complex differentiation process in which cell growth is followed by the synthesis and secretion of pectinaceous mucilage. A number of genes have been identified affecting mucilage secretory cell differentiation, including MUCILAGE-MODIFIED4 (MUM4). mum4 mutants produce a reduced amount of mucilage and cloning of MUM4 revealed that it encodes a UDP-L-rhamnose synthase that is developmentally up-regulated to provide rhamnose for mucilage pectin synthesis. To identify additional genes acting in mucilage synthesis and secretion, a screen for enhancers of the mum4 phenotype was performed. Eight mum enhancers (men) have been identified, two of which result from defects in known mucilage secretory cell genes (MUM2 and MYB61). Our results show that, in a mum4 background, mutations in MEN1, MEN4, and MEN5 lead to further reductions in mucilage compared to mum4 single mutants, suggesting that they are involved in mucilage synthesis or secretion. Conversely, mutations in MEN2 and MEN6 appear to affect mucilage release rather than quantity. With the exception of men4, whose single mutant exhibits reduced mucilage, none of these genes have a single mutant phenotype, suggesting that they would not have been identified outside the compromised mum4 background.
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Affiliation(s)
| | - Maria M. Villota
- Department of Biology, Carleton University, Ottawa, ON, Canada K1S 5B6
- Agriculture and Agri-Food Canada, Eastern Cereal and Oilseed Research Centre, Ottawa, ON, Canada K1A 0C6
| | - Owen Rowland
- Department of Biology, Carleton University, Ottawa, ON, Canada K1S 5B6
| | - Rajagopal Subramaniam
- Agriculture and Agri-Food Canada, Eastern Cereal and Oilseed Research Centre, Ottawa, ON, Canada K1A 0C6
| | - Tamara L. Western
- Department of Biology, McGill University, Montreal, QC, Canada H3A 1B1
- To whom correspondence should be addressed: E-mail:
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99
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Li SF, Milliken ON, Pham H, Seyit R, Napoli R, Preston J, Koltunow AM, Parish RW. The Arabidopsis MYB5 transcription factor regulates mucilage synthesis, seed coat development, and trichome morphogenesis. THE PLANT CELL 2009; 21:72-89. [PMID: 19136646 PMCID: PMC2648076 DOI: 10.1105/tpc.108.063503] [Citation(s) in RCA: 156] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2008] [Revised: 12/02/2008] [Accepted: 12/20/2008] [Indexed: 05/18/2023]
Abstract
The Arabidopsis thaliana MYB5 gene is expressed in trichomes and seeds, including the seed coat. Constitutive expression of MYB5 resulted in the formation of more small trichomes and ectopic trichomes and a reduction in total leaf trichome numbers and branching. A myb5 mutant displayed minimal changes in trichome morphology, while a myb23 mutant produced increased numbers of small trichomes and two-branched trichomes. A myb5 myb23 double mutant developed more small rosette trichomes and two-branched trichomes than the single mutants. These results indicate that MYB5 and MYB23 regulate trichome extension and branching. The seed coat epidermal cells of myb5 and myb5 myb23 were irregular in shape, developed flattened columellae, and produced less mucilage than those of the wild type. Among the downregulated genes identified in the myb5 seeds using microarray analysis were ABE1 and ABE4 (alpha/beta fold hydrolase/esterase genes), MYBL2, and GLABRA2. The same genes were also downregulated in transparent testa glabra1 (ttg1) seeds, suggesting that MYB5 collaborates with TTG1 in seed coat development. These genes were upregulated in leaves and roots by ectopically expressed MYB5. The MYBL2, ABE1, and ABE4 promoters were active in seeds, including seed coats, and the latter two also in trichomes. Models of the MYB5 regulatory networks involved in seed coat and trichome development are presented.
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Affiliation(s)
- Song Feng Li
- Department of Botany, School of Life Sciences, La Trobe University, Bundoora, Victoria 3086, Australia
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100
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Abstract
Seed dormancy allows seeds to overcome periods that are unfavourable for seedling established and is therefore important for plant ecology and agriculture. Several processes are known to be involved in the induction of dormancy and in the switch from the dormant to the germinating state. The role of plant hormones, the different tissues and genes involved, including newly identified genes in dormancy and germination are described in this chapter, as well as the use transcriptome, proteome and metabolome analyses to study these mechanistically not well understood processes.
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Affiliation(s)
- Leónie Bentsink
- Department of Molecular Plant Physiology, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Maarten Koornneef
- Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, 50829 Cologne, Germany
- Laboratory of Genetics, Wageningen University, Arboretumlaan 4, 6703 BD Wageningen, The Netherlands
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