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Pommerrenig B, Popko J, Heilmann M, Schulmeister S, Dietel K, Schmitt B, Stadler R, Feussner I, Sauer N. SUCROSE TRANSPORTER 5 supplies Arabidopsis embryos with biotin and affects triacylglycerol accumulation. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 73:392-404. [PMID: 23031218 PMCID: PMC3787789 DOI: 10.1111/tpj.12037] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Revised: 08/22/2012] [Accepted: 09/24/2012] [Indexed: 05/18/2023]
Abstract
The Arabidopsis SUC5 protein represents a classical sucrose/H(+) symporter. Functional analyses previously revealed that SUC5 also transports biotin, an essential co-factor for fatty acid synthesis. However, evidence for a dual role in transport of the structurally unrelated compounds sucrose and biotin in plants was lacking. Here we show that SUC5 localizes to the plasma membrane, and that the SUC5 gene is expressed in developing embryos, confirming the role of the SUC5 protein as substrate carrier across apoplastic barriers in seeds. We show that transport of biotin but not of sucrose across these barriers is impaired in suc5 mutant embryos. In addition, we show that SUC5 is essential for the delivery of biotin into the embryo of biotin biosynthesis-defective mutants (bio1 and bio2). We compared embryo and seedling development as well as triacylglycerol accumulation and fatty acid composition in seeds of single mutants (suc5, bio1 or bio2), double mutants (suc5 bio1 and suc5 bio2) and wild-type plants. Although suc5 mutants were like the wild-type, bio1 and bio2 mutants showed developmental defects and reduced triacylglycerol contents. In suc5 bio1 and suc5 bio2 double mutants, developmental defects were severely increased and the triacylglycerol content was reduced to a greater extent in comparison to the single mutants. Supplementation with externally applied biotin helped to reduce symptoms in both single and double mutants, but the efficacy of supplementation was significantly lower in double than in single mutants, showing that transport of biotin into the embryo is lower in the absence of SUC5.
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Affiliation(s)
- Benjamin Pommerrenig
- Molekulare Pflanzenphysiologie, Friedrich-Alexander Universität Erlangen-Nürnberg, Staudtstraße 5, D-91058, Erlangen, Germany.
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52
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Xing Q, Creff A, Waters A, Tanaka H, Goodrich J, Ingram GC. ZHOUPI controls embryonic cuticle formation via a signalling pathway involving the subtilisin protease ABNORMAL LEAF-SHAPE1 and the receptor kinases GASSHO1 and GASSHO2. Development 2013; 140:770-9. [PMID: 23318634 DOI: 10.1242/dev.088898] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Seed production in angiosperms requires tight coordination of the development of the embryo and the endosperm. The endosperm-specific transcription factor ZHOUPI has previously been shown to play a key role in this process, by regulating both endosperm breakdown and the formation of the embryonic cuticle. To what extent these processes are functionally linked is, however, unclear. In order to address this issue we have concentrated on the subtilisin-like serine protease encoding gene ABNORMAL LEAF-SHAPE1. Expression of ABNORMAL LEAF-SHAPE1 is endosperm specific, and dramatically decreased in zhoupi mutants. We show that, although ABNORMAL LEAF-SHAPE1 is required for normal embryonic cuticle formation, it plays no role in regulating endosperm breakdown. Furthermore, we show that re-introducing ABNORMAL LEAF-SHAPE1 expression in the endosperm of zhoupi mutants partially rescues embryonic cuticle formation without rescuing their persistent endosperm phenotype. Thus, we conclude that ALE1 can normalize cuticle formation in the absence of endosperm breakdown, and that ZHOUPI thus controls two genetically separable developmental processes. Finally, our genetic study shows that ZHOUPI and ABNORMAL LEAF-SHAPE1 promotes formation of embryonic cuticle via a pathway involving embryonically expressed receptor kinases GASSHO1 and GASSHO2. We therefore provide a molecular framework of inter-tissue communication for embryo-specific cuticle formation during embryogenesis.
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Affiliation(s)
- Qian Xing
- Institute of Molecular Plant Sciences, University of Edinburgh, King's Buildings, Mayfield Road, Edinburgh EH9 3JH, UK
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53
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Andriotis VM, Pike MJ, Schwarz SL, Rawsthorne S, Wang TL, Smith AM. Altered starch turnover in the maternal plant has major effects on Arabidopsis fruit growth and seed composition. PLANT PHYSIOLOGY 2012; 160:1175-86. [PMID: 22942388 PMCID: PMC3490605 DOI: 10.1104/pp.112.205062] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Accepted: 08/30/2012] [Indexed: 05/20/2023]
Abstract
Mature seeds of both the high-starch starch-excess1 (sex1) mutant and the almost starchless phosphoglucomutase1 mutant of Arabidopsis (Arabidopsis thaliana) have 30% to 40% less lipid than seeds of wild-type plants. We show that this is a maternal effect and is not attributable to the defects in starch metabolism in the embryo itself. Low lipid contents and consequent slow postgerminative growth are seen only in mutant embryos that develop on maternal plants with mutant phenotypes. Mutant embryos that develop on plants with wild-type starch metabolism have wild-type lipid contents and postgerminative growth. The maternal effect on seed lipid content is attributable to carbohydrate starvation in the mutant fruit at night. Fruits on sex1 plants grow more slowly than those on wild-type plants, particularly at night, and have low sugars and elevated expression of starvation genes at night. Transcript levels of the transcription factor WRINKLED1, implicated in lipid synthesis, are reduced at night in sex1 but not in wild-type seeds, and so are transcript levels of key enzymes of glycolysis and fatty acid synthesis. sex1 embryos develop more slowly than wild-type embryos. We conclude that the reduced capacity of mutant plants to convert starch to sugars in leaves at night results in low nighttime carbohydrate availability in the developing fruit. This in turn reduces the rate of development and expression of genes encoding enzymes of storage product accumulation in the embryo. Thus, the supply of carbohydrate from the maternal plant to the developing fruit at night can have an important influence on oilseed composition and on postgerminative growth.
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54
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Wang L, Ruan YL. New insights into roles of cell wall invertase in early seed development revealed by comprehensive spatial and temporal expression patterns of GhCWIN1 in cotton. PLANT PHYSIOLOGY 2012; 160:777-87. [PMID: 22864582 PMCID: PMC3461555 DOI: 10.1104/pp.112.203893] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Accepted: 08/02/2012] [Indexed: 05/18/2023]
Abstract
Despite substantial evidence on the essential roles of cell wall invertase (CWIN) in seed filling, it remains largely unknown how CWIN exerts its regulation early in seed development, a critical stage that sets yield potential. To fill this knowledge gap, we systematically examined the spatial and temporal expression patterns of a major CWIN gene, GhCWIN1, in cotton (Gossypium hirsutum) seeds from prefertilization to prestorage phase. GhCWIN1 messenger RNA was abundant at the innermost seed coat cell layer at 5 d after anthesis but became undetectable at 10 d after anthesis, at the onset of its differentiation into transfer cells characterized by wall ingrowths, suggesting that CWIN may negatively regulate transfer cell differentiation. Within the filial tissues, GhCWIN1 transcript was detected in endosperm cells undergoing nuclear division but not in those cells at the cellularization stage, with similar results observed in Arabidopsis (Arabidopsis thaliana) endosperm for CWIN, AtCWIN4. These findings indicate a function of CWIN in nuclear division but not cell wall biosynthesis in endosperm, contrasting to the role proposed for sucrose synthase (Sus). Further analyses revealed a preferential expression pattern of GhCWIN1 and AtCWIN4 in the provascular region of the torpedo embryos in cotton and Arabidopsis seed, respectively, indicating a role of CWIN in vascular initiation. Together, these novel findings provide insights into the roles of CWIN in regulating early seed development spatially and temporally. By comparing with previous studies on Sus expression and in conjunction with the expression of other related genes, we propose models of CWIN- and Sus-mediated regulation of early seed development.
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MESH Headings
- Arabidopsis/genetics
- Arabidopsis/metabolism
- Cell Differentiation
- Cell Nucleus Division
- Cell Wall/enzymology
- Cell Wall/genetics
- Cloning, Molecular
- DNA, Complementary/genetics
- DNA, Complementary/metabolism
- Enzyme Activation
- Gene Expression Regulation, Enzymologic
- Gene Expression Regulation, Plant
- Genes, Plant
- Giant Cells/metabolism
- Glucosyltransferases/genetics
- Glucosyltransferases/metabolism
- Gossypium/embryology
- Gossypium/enzymology
- Gossypium/genetics
- Plant Proteins/genetics
- Plant Proteins/metabolism
- Plant Vascular Bundle/genetics
- Plant Vascular Bundle/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Plant/genetics
- Seeds/enzymology
- Seeds/genetics
- Seeds/growth & development
- Sequence Analysis, RNA
- Time Factors
- beta-Fructofuranosidase/genetics
- beta-Fructofuranosidase/metabolism
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Affiliation(s)
- Lu Wang
- Australia-China Research Centre for Crop Improvement and School of Environmental and Life Sciences, University of Newcastle, Callaghan, New South Wales 2308, Australia
| | - Yong-Ling Ruan
- Australia-China Research Centre for Crop Improvement and School of Environmental and Life Sciences, University of Newcastle, Callaghan, New South Wales 2308, Australia
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Li J, Berger F. Endosperm: food for humankind and fodder for scientific discoveries. THE NEW PHYTOLOGIST 2012; 195:290-305. [PMID: 22642307 DOI: 10.1111/j.1469-8137.2012.04182.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The endosperm is an essential constituent of seeds in flowering plants. It originates from a fertilization event parallel to the fertilization that gives rise to the embryo. The endosperm nurtures embryo development and, in some species including cereals, stores the seed reserves and represents a major source of food for humankind. Endosperm biology is characterized by specific features, including idiosyncratic cellular controls of cell division and epigenetic controls associated with parental genomic imprinting. This review attempts a comprehensive summary of our current knowledge of endosperm development and highlights recent advances in this field.
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Affiliation(s)
- Jing Li
- Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, 117604 Singapore
| | - Frédéric Berger
- Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, 117604 Singapore
- Department of Biological Sciences, National University of Singapore, Singapore
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56
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Hehenberger E, Kradolfer D, Köhler C. Endosperm cellularization defines an important developmental transition for embryo development. Development 2012; 139:2031-9. [PMID: 22535409 DOI: 10.1242/dev.077057] [Citation(s) in RCA: 134] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The endosperm is a terminal seed tissue that is destined to support embryo development. In most angiosperms, the endosperm develops initially as a syncytium to facilitate rapid seed growth. The transition from the syncytial to the cellularized state occurs at a defined time point during seed development. Manipulating the timing of endosperm cellularization through interploidy crosses negatively impacts on embryo growth, suggesting that endosperm cellularization is a critical step during seed development. In this study, we show that failure of endosperm cellularization in fertilization independent seed 2 (fis2) and endosperm defective 1 (ede1) Arabidopsis mutants correlates with impaired embryo development. Restoration of endosperm cellularization in fis2 seeds by reducing expression of the MADS-box gene AGAMOUS-LIKE 62 (AGL62) promotes embryo development, strongly supporting an essential role of endosperm cellularization for viable seed formation. Endosperm cellularization failure in fis2 seeds correlates with increased hexose levels, suggesting that arrest of embryo development is a consequence of failed nutrient translocation to the developing embryo. Finally, we demonstrate that AGL62 is a direct target gene of FIS Polycomb group repressive complex 2 (PRC2), establishing the molecular basis for FIS PRC2-mediated endosperm cellularization.
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Affiliation(s)
- Elisabeth Hehenberger
- Department of Biology and Zurich-Basel Plant Science Center, Swiss Federal Institute of Technology, CH-8092 Zurich, Switzerland
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57
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Schneider S, Hulpke S, Schulz A, Yaron I, Höll J, Imlau A, Schmitt B, Batz S, Wolf S, Hedrich R, Sauer N. Vacuoles release sucrose via tonoplast-localised SUC4-type transporters. PLANT BIOLOGY (STUTTGART, GERMANY) 2012; 14:325-36. [PMID: 21972845 DOI: 10.1111/j.1438-8677.2011.00506.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Arabidopsis thaliana has seven genes for functionally active sucrose transporters. Together with sucrose transporters from other dicot and monocot plants, these proteins form four separate phylogenetic groups. Group-IV includes the Arabidopsis protein SUC4 (synonym SUT4) and related proteins from monocots and dicots. These Group-IV sucrose transporters were reported to be either tonoplast- or plasma membrane-localised, and in heterologous expression systems were shown to act as sucrose/H(+) symporters. Here, we present comparative analyses of the subcellular localisation of the Arabidopsis SUC4 protein and of several other Group-IV sucrose transporters, studies on tissue specificity of the Arabidopsis SUC4 promoter, phenotypic characterisations of Atsuc4.1 mutants and AtSUC4 overexpressing (AtSUC4-OX) plants, and functional comparisons of Atsuc4.1 and AtSUC4-OX vacuoles. Our data show that SUC4-type sucrose transporters from different plant families (Brassicaceae, Cucurbitaceae and Solanaceae) localise exclusively to the tonoplast, demonstrating that vacuolar sucrose transport is a common theme of all SUC4-type proteins. AtSUC4 expression is confined to the stele of Arabidopsis roots, developing anthers and meristematic tissues in all aerial parts. Analyses of the carbohydrate content of WT and mutant seedlings revealed reduced sucrose content in AtSUC4-OX seedlings. This is in line with patch-clamp analyses of AtSUC4-OX vacuoles that characterise AtSUC4 as a sucrose/H(+) symporter directly in the tonoplast membrane.
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Affiliation(s)
- S Schneider
- Molekulare Pflanzenphysiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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58
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59
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Melkus G, Rolletschek H, Fuchs J, Radchuk V, Grafahrend-Belau E, Sreenivasulu N, Rutten T, Weier D, Heinzel N, Schreiber F, Altmann T, Jakob PM, Borisjuk L. Dynamic ¹³C/¹ H NMR imaging uncovers sugar allocation in the living seed. PLANT BIOTECHNOLOGY JOURNAL 2011; 9:1022-37. [PMID: 21535356 DOI: 10.1111/j.1467-7652.2011.00618.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Seed growth and accumulation of storage products relies on the delivery of sucrose from the maternal to the filial tissues. The transport route is hidden inside the seed and has never been visualized in vivo. Our approach, based on high-field nuclear magnetic resonance and a custom made (13)C/(1) H double resonant coil, allows the non-invasive imaging and monitoring of sucrose allocation within the seed. The new technique visualizes the main stream of sucrose and determines its velocity during the grain filling in barley (Hordeum vulgare L.). Quantifiable dynamic images are provided, which allow observing movement of (13)C-sucrose at a sub-millimetre level of resolution. The analysis of genetically modified barley grains (Jekyll transgenic lines, seg8 and Risø13 mutants) demonstrated that sucrose release via the nucellar projection towards the endosperm provides an essential mean for the control of seed growth by maternal organism. The sucrose allocation was further determined by structural and metabolic features of endosperm. Sucrose monitoring was integrated with an in silico flux balance analysis, representing a powerful platform for non-invasive study of seed filling in crops.
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Affiliation(s)
- Gerd Melkus
- Institute of Experimental Physics, University of Würzburg, Am Hubland, Würzburg, Germany
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Li F, Ma C, Wang X, Gao C, Zhang J, Wang Y, Cong N, Li X, Wen J, Yi B, Shen J, Tu J, Fu T. Characterization of Sucrose transporter alleles and their association with seed yield-related traits in Brassica napus L. BMC PLANT BIOLOGY 2011; 11:168. [PMID: 22112023 PMCID: PMC3248380 DOI: 10.1186/1471-2229-11-168] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Accepted: 11/23/2011] [Indexed: 05/20/2023]
Abstract
BACKGROUND Sucrose is the primary photosynthesis product and the principal translocating form within higher plants. Sucrose transporters (SUC/SUT) play a critical role in phloem loading and unloading. Photoassimilate transport is a major limiting factor for seed yield. Our previous research demonstrated that SUT co-localizes with yield-related quantitative trait loci. This paper reports the isolation of BnA7.SUT1 alleles and their promoters and their association with yield-related traits. RESULTS Two novel BnA7.SUT1 genes were isolated from B. napus lines 'Eagle' and 'S-1300' and designated as BnA7.SUT1.a and BnA7.SUT1.b, respectively. The BnA7.SUT1 protein exhibited typical SUT features and showed high amino acid homology with related species. Promoters of BnA7.SUT1.a and BnA7.SUT1.b were also isolated and classified as pBnA7.SUT1.a and pBnA7.SUT1.b, respectively. Four dominant sequence-characterized amplified region markers were developed to distinguish BnA7.SUT1.a and BnA7.SUT1.b. The two genes were estimated as alleles with two segregating populations (F2 and BC1) obtained by crossing '3715'×'3769'. BnA7.SUT1 was mapped to the A7 linkage group of the TN doubled haploid population. In silico analysis of 55 segmental BnA7.SUT1 alleles resulted three BnA7.SUT1 clusters: pBnA7.SUT1.a- BnA7.SUT1.a (type I), pBnA7.SUT1.b- BnA7.SUT1.a (type II), and pBnA7.SUT1.b- BnA7.SUT1.b (type III). Association analysis with a diverse panel of 55 rapeseed lines identified single nucleotide polymorphisms (SNPs) in promoter and coding domain sequences of BnA7.SUT1 that were significantly associated with one of three yield-related traits: number of effective first branches (EFB), siliques per plant (SP), and seed weight (n = 1000) (TSW) across all four environments examined. SNPs at other BnA7.SUT1 sites were also significantly associated with at least one of six yield-related traits: EFB, SP, number of seeds per silique, seed yield per plant, block yield, and TSW. Expression levels varied over various tissue/organs at the seed-filling stage, and BnA7.SUT1 expression positively correlated with EFB and TSW. CONCLUSIONS Sequence, mapping, association, and expression analyses collectively showed significant diversity between the two BnA7.SUT1 alleles, which control some of the phenotypic variation for branch number and seed weight in B. napus consistent with expression levels. The associations between allelic variation and yield-related traits may facilitate selection of better genotypes in breeding.
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Affiliation(s)
- Fupeng Li
- National Key Laboratory of Crop Genetic Improvement, National Center of Rapeseed Improvement in Wuhan, Huazhong Agricultural University, Wuhan 430070, China
| | - Chaozhi Ma
- National Key Laboratory of Crop Genetic Improvement, National Center of Rapeseed Improvement in Wuhan, Huazhong Agricultural University, Wuhan 430070, China
| | - Xia Wang
- National Key Laboratory of Crop Genetic Improvement, National Center of Rapeseed Improvement in Wuhan, Huazhong Agricultural University, Wuhan 430070, China
| | - Changbin Gao
- National Key Laboratory of Crop Genetic Improvement, National Center of Rapeseed Improvement in Wuhan, Huazhong Agricultural University, Wuhan 430070, China
| | - Jianfeng Zhang
- National Key Laboratory of Crop Genetic Improvement, National Center of Rapeseed Improvement in Wuhan, Huazhong Agricultural University, Wuhan 430070, China
| | - Yuanyuan Wang
- National Key Laboratory of Crop Genetic Improvement, National Center of Rapeseed Improvement in Wuhan, Huazhong Agricultural University, Wuhan 430070, China
| | - Na Cong
- National Key Laboratory of Crop Genetic Improvement, National Center of Rapeseed Improvement in Wuhan, Huazhong Agricultural University, Wuhan 430070, China
| | - Xinghua Li
- National Key Laboratory of Crop Genetic Improvement, National Center of Rapeseed Improvement in Wuhan, Huazhong Agricultural University, Wuhan 430070, China
| | - Jing Wen
- National Key Laboratory of Crop Genetic Improvement, National Center of Rapeseed Improvement in Wuhan, Huazhong Agricultural University, Wuhan 430070, China
| | - Bin Yi
- National Key Laboratory of Crop Genetic Improvement, National Center of Rapeseed Improvement in Wuhan, Huazhong Agricultural University, Wuhan 430070, China
| | - Jinxiong Shen
- National Key Laboratory of Crop Genetic Improvement, National Center of Rapeseed Improvement in Wuhan, Huazhong Agricultural University, Wuhan 430070, China
| | - Jinxing Tu
- National Key Laboratory of Crop Genetic Improvement, National Center of Rapeseed Improvement in Wuhan, Huazhong Agricultural University, Wuhan 430070, China
| | - Tingdong Fu
- National Key Laboratory of Crop Genetic Improvement, National Center of Rapeseed Improvement in Wuhan, Huazhong Agricultural University, Wuhan 430070, China
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Berger N, Dubreucq B, Roudier F, Dubos C, Lepiniec L. Transcriptional regulation of Arabidopsis LEAFY COTYLEDON2 involves RLE, a cis-element that regulates trimethylation of histone H3 at lysine-27. THE PLANT CELL 2011; 23:4065-78. [PMID: 22080598 PMCID: PMC3246333 DOI: 10.1105/tpc.111.087866] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Revised: 10/11/2011] [Accepted: 10/30/2011] [Indexed: 05/17/2023]
Abstract
LEAFY COTYLEDON2 (LEC2) is a master regulator of seed development in Arabidopsis thaliana. In vegetative organs, LEC2 expression is negatively regulated by Polycomb Repressive Complex2 (PRC2) that catalyzes histone H3 Lys 27 trimethylation (H3K27me3) and plays a crucial role in developmental phase transitions. To characterize the cis-regulatory elements involved in the transcriptional regulation of LEC2, molecular dissections and functional analyses of the promoter region were performed in vitro, both in yeast and in planta. Two cis-activating elements and a cis-repressing element (RLE) that is required for H3K27me3 marking were characterized. Remarkably, insertion of the RLE cis-element into pF3H, an unrelated promoter, is sufficient for repressing its transcriptional activity in different tissues. Besides improving our understanding of LEC2 regulation, this study provides important new insights into the mechanisms underlying H3K27me3 deposition and PRC2 recruitment at a specific locus in plants.
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Affiliation(s)
- Nathalie Berger
- Institut Jean-Pierre Bourgin, Unité Mixte de Recherche 1318 Institut National de la Recherche Agronomique–Agro-ParisTech, Saclay Plant Sciences, 78026 Versailles cedex, France
| | - Bertrand Dubreucq
- Institut Jean-Pierre Bourgin, Unité Mixte de Recherche 1318 Institut National de la Recherche Agronomique–Agro-ParisTech, Saclay Plant Sciences, 78026 Versailles cedex, France
| | - François Roudier
- Institut de Biologie de l'Ecole Normale Supérieure, Centre National de la Recherche Scientifique Unité Mixte de Recherche 8197–Institut National de la Santé et de la Recherche Médicale U1024, 75230 Paris cedex 05, France
| | - Christian Dubos
- Institut Jean-Pierre Bourgin, Unité Mixte de Recherche 1318 Institut National de la Recherche Agronomique–Agro-ParisTech, Saclay Plant Sciences, 78026 Versailles cedex, France
| | - Loïc Lepiniec
- Institut Jean-Pierre Bourgin, Unité Mixte de Recherche 1318 Institut National de la Recherche Agronomique–Agro-ParisTech, Saclay Plant Sciences, 78026 Versailles cedex, France
- Address correspondence to
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Abbadi A, Leckband G. Rapeseed breeding for oil content, quality, and sustainability. EUR J LIPID SCI TECH 2011. [DOI: 10.1002/ejlt.201100063] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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63
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Henry C, Rabot A, Laloi M, Mortreau E, Sigogne M, Leduc N, Lemoine R, Sakr S, Vian A, Pelleschi-Travier S. Regulation of RhSUC2, a sucrose transporter, is correlated with the light control of bud burst in Rosa sp. PLANT, CELL & ENVIRONMENT 2011; 34:1776-89. [PMID: 21635271 DOI: 10.1111/j.1365-3040.2011.02374.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
In roses, light is a central environmental factor controlling bud break and involves a stimulation of sugar metabolism. Very little is known about the role of sucrose transporters in the bud break process and its regulation by light. In this study, we show that sugar promotes rose bud break and that bud break is accompanied by an import of sucrose. Radio-labelled sucrose accumulation is higher in buds exposed to light than to darkness and involves an active component. Several sucrose transporter (RhSUC1, 2, 3 and 4) transcripts are expressed in rose tissues, but RhSUC2 transcript level is the only one induced in buds exposed to light after removing the apical dominance. RhSUC2 is preferentially expressed in bursting buds and stems. Functional analyses in baker's yeast demonstrate that RhSUC2 encodes a sucrose/proton co-transporter with a K(m) value of 2.99 mm at pH 4.5 and shows typical features of sucrose symporters. We therefore propose that bud break photocontrol partly depends upon the modulation of sucrose import into buds by RhSUC2.
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Affiliation(s)
- Clemence Henry
- Universite D'Angers, UFR Sciences, UMR-462 SAGAH, 2 Bd Lavoisier, F-49045 Angers Cedex, France
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64
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Abid G, Muhovski Y, Jacquemin JM, Mingeot D, Sassi K, Toussaint A, Baudoin JP. Characterization and expression profile analysis of a sucrose synthase gene from common bean (Phaseolus vulgaris L.) during seed development. Mol Biol Rep 2011; 39:1133-43. [PMID: 21573790 DOI: 10.1007/s11033-011-0842-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2010] [Accepted: 05/05/2011] [Indexed: 11/28/2022]
Abstract
A full-length cDNA encoding common bean (Phaseolus vulgaris L.) sucrose synthase (designated as Pv_BAT93 Sus), which catalyses the synthesis and cleavage of sucrose, was isolated from seeds at 15 days after pollination (DAP) by rapid amplification of cDNA ends (RACE). The full-length cDNA of Pv_BAT93 Sus had a 2,418 bp open reading frame (ORF) encoding a protein of 806 amino acid residues. Sequence comparison analysis showed that Pv_BAT93 Sus was very similar to several members of the sucrose synthase family of other plant species. Tissue expression pattern analysis showed that Pv_BAT93 Sus was expressed in leaves, flowers, stems, roots, cotyledons, and particularly during seed development. Expression studies using in situ hybridization revealed altered spatial and temporal patterns of Sus expression in the EMS mutant relative to wild-type and confirmed Sus expression in common bean developing seeds. The expression and accumulation of Sus mRNA was clearly shown in several tissues, such as the suspensor and embryo, but also in the transfer cells and endothelium. The results highlight the diverse roles that Sus might play during seed development in common bean.
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Affiliation(s)
- Ghassen Abid
- University of Liège-Gembloux Agro-Bio Tech., Unit of Tropical Crop Husbandry and Horticulture, Gembloux Agricultural University, Passage des Déportés 2, 5030 Gembloux, Belgium.
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Ayre BG. Membrane-transport systems for sucrose in relation to whole-plant carbon partitioning. MOLECULAR PLANT 2011; 4:377-94. [PMID: 21502663 DOI: 10.1093/mp/ssr014] [Citation(s) in RCA: 190] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Sucrose is the principal product of photosynthesis used for the distribution of assimilated carbon in plants. Transport mechanisms and efficiency influence photosynthetic productivity by relieving product inhibition and contribute to plant vigor by controlling source/sink relationships and biomass partitioning. Sucrose is synthesized in the cytoplasm and may move cell to cell through plasmodesmata or may cross membranes to be compartmentalized or exported to the apoplasm for uptake into adjacent cells. As a relatively large polar compound, sucrose requires proteins to facilitate efficient membrane transport. Transport across the tonoplast by facilitated diffusion, antiport with protons, and symport with protons have been proposed; for transport across plasma membranes, symport with protons and a mechanism resembling facilitated diffusion are evident. Despite decades of research, only symport with protons is well established at the molecular level. This review aims to integrate recent and older studies on sucrose flux across membranes with principles of whole-plant carbon partitioning.
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Affiliation(s)
- Brian G Ayre
- University of North Texas, Department of Biological Sciences, Denton, Texas, USA.
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68
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Ingram GC. Family life at close quarters: communication and constraint in angiosperm seed development. PROTOPLASMA 2010; 247:195-214. [PMID: 20661606 DOI: 10.1007/s00709-010-0184-y] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Accepted: 07/12/2010] [Indexed: 05/05/2023]
Abstract
The formation of viable angiosperm seeds involves the co-ordinated growth and development of three genetically distinct organisms, the maternally derived seed coat and the zygotic embryo and endosperm. The physical relationships of these tissues are initially established during the specification and differentiation of the female gametophyte within the tissues of the developing ovule. The molecular programmes implicated in both ovule and seed development involve elements of globally important pathways (such as auxin signalling), as well as ovule- and seed-specific pathways. Recurrent themes, such as the precisely controlled death of specific cell types and the regulation of cell-cell communication and nutrition by the selective establishment of symplastic and apoplastic barriers, appear to play key roles in both pre- and post-fertilization seed development. Much of post-fertilization seed growth occurs during a key developmental window shortly after fertilization and involves the dramatic expansion of the young endosperm, constrained by surrounding maternal tissues. The complex tissue-specific regulation of carbohydrate metabolism in specific seed compartments has been shown to provide a driving force for this early seed expansion. The embryo, which is arguably the most important component of the seed, appears to be only minimally involved in early seed development. Given the evolutionary and agronomic importance of angiosperm seeds, the complex combination of communication pathways which co-ordinate their growth and development remains remarkably poorly understood.
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69
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Jeong SW, Das PK, Jeoung SC, Song JY, Lee HK, Kim YK, Kim WJ, Park YI, Yoo SD, Choi SB, Choi G, Park YI. Ethylene suppression of sugar-induced anthocyanin pigmentation in Arabidopsis. PLANT PHYSIOLOGY 2010; 154:1514-31. [PMID: 20876338 PMCID: PMC2971625 DOI: 10.1104/pp.110.161869] [Citation(s) in RCA: 146] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2010] [Accepted: 09/25/2010] [Indexed: 05/18/2023]
Abstract
Anthocyanin accumulation is regulated negatively by ethylene signaling and positively by sugar and light signaling. However, the antagonistic interactions underlying these signalings remain to be elucidated fully. We show that ethylene inhibits anthocyanin accumulation induced by sucrose (Suc) and light by suppressing the expression of transcription factors that positively regulate anthocyanin biosynthesis, including GLABRA3, TRANSPARENT TESTA8, and PRODUCTION OF ANTHOCYANIN PIGMENT1, while stimulating the concomitant expression of the negative R3-MYB regulator MYBL2. Genetic analyses show that the ethylene-mediated suppression of anthocyanin accumulation is dependent upon ethylene signaling components responsible for the triple response. Furthermore, these positive and negative signaling pathways appear to be under photosynthetic control. Suc and light induction of anthocyanin accumulation was almost fully inhibited in wild-type Arabidopsis (Arabidopsis thaliana) ecotype Columbia and ethylene (ethylene response1 [etr1-1]) and light (long hypocotyl1 [hy1], cryptochrome1/2, and hy5) signaling mutants treated with the photosynthetic electron transport inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea. The transcript level of the sugar transporter gene SUC1 was enhanced in ecotype Columbia treated with the ethylene-binding inhibitor silver and in etr1-1, ethylene insensitive2 (ein2-1), and ein3 ein3-like1 mutants. In contrast, 3-(3,4-dichlorophenyl)-1,1-dimethylurea treatment reduced SUC1 expression, which indicates strongly that SUC1 represents an integrator for signals provided by sugar, light, and ethylene. SUC1 mutations lowered accumulations of anthocyanin pigment, soluble sugar content, and ethylene production in response to Suc and light signals. These data demonstrate that the suppression of SUC1 expression by ethylene inhibits Suc-induced anthocyanin accumulation in the presence of light and, hence, fine-tunes anthocyanin homeostasis.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | - Youn-Il Park
- Department of Biological Science and Graduate School of Analytical Science and Technology, Chungnam National University, Daejeon 305–764, Korea (S.-W.J., P.K.D., J.-Y.S., H.K.L., Y.-I.P.); Division of Advanced Technology, Korea Research Institute of Standards and Science, Daejeon 305–340, Korea (S.-W.J., S.C.J.); GreenGene Biotech (Y.-K.K.) and Division of Bioscience and Bioinformatics (S.-B.C.), Myongji University, Yongin 449–728, Korea; Division of Biotechnology, Catholic University, Bucheon 420–743, Korea (W.J.K., Y.I.P.); Department of Biological Science, Sungkyunkwan University, Suwon 440–764, Korea (S.-D.Y.); Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 305–701, Korea (G.C.)
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70
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Ibraheem O, Botha CEJ, Bradley G. In silico analysis of cis-acting regulatory elements in 5' regulatory regions of sucrose transporter gene families in rice (Oryza sativa Japonica) and Arabidopsis thaliana. Comput Biol Chem 2010; 34:268-83. [PMID: 21036669 DOI: 10.1016/j.compbiolchem.2010.09.003] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2010] [Revised: 09/14/2010] [Accepted: 09/27/2010] [Indexed: 11/18/2022]
Abstract
The regulation of gene expression involves a multifarious regulatory system. Each gene contains a unique combination of cis-acting regulatory sequence elements in the 5' regulatory region that determines its temporal and spatial expression. Cis-acting regulatory elements are essential transcriptional gene regulatory units; they control many biological processes and stress responses. Thus a full understanding of the transcriptional gene regulation system will depend on successful functional analyses of cis-acting elements. Cis-acting regulatory elements present within the 5' regulatory region of the sucrose transporter gene families in rice (Oryza sativa Japonica cultivar-group) and Arabidopsis thaliana, were identified using a bioinformatics approach. The possible cis-acting regulatory elements were predicted by scanning 1.5kbp of 5' regulatory regions of the sucrose transporter genes translational start sites, using Plant CARE, PLACE and Genomatix Matinspector professional databases. Several cis-acting regulatory elements that are associated with plant development, plant hormonal regulation and stress response were identified, and were present in varying frequencies within the 1.5kbp of 5' regulatory region, among which are; A-box, RY, CAT, Pyrimidine-box, Sucrose-box, ABRE, ARF, ERE, GARE, Me-JA, ARE, DRE, GA-motif, GATA, GT-1, MYC, MYB, W-box, and I-box. This result reveals the probable cis-acting regulatory elements that possibly are involved in the expression and regulation of sucrose transporter gene families in rice and Arabidopsis thaliana during cellular development or environmental stress conditions.
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Affiliation(s)
- Omodele Ibraheem
- Plant Stress Response Group, Department of Biochemistry & Microbiology, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa
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Abstract
Flowering plants have evolved to be a predominant life form on earth. A common principle of flowering plants and probably one of the main reasons for their evolutionary success is the rapid development of an embryo next to a supporting tissue called the endosperm. The embryo and the endosperm are protected by surrounding maternal tissues, the integuments, and the trinity of integuments, embryo and endosperm comprise the plant seed. For proper seed development, these three structures have to develop in a highly controlled and co-ordinated manner, representing a paradigm for cell-cell communication during development. Communication pathways between the endosperm and the seed coat are now beginning to be unravelled. Moreover, recently isolated mutants affecting plant reproduction have allowed a genetic dissection of seed development, and revealed that the embryo plays a previously unrecognized yet important role in co-ordinating seed development.
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North H, Baud S, Debeaujon I, Dubos C, Dubreucq B, Grappin P, Jullien M, Lepiniec L, Marion-Poll A, Miquel M, Rajjou L, Routaboul JM, Caboche M. Arabidopsis seed secrets unravelled after a decade of genetic and omics-driven research. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2010; 61:971-81. [PMID: 20409271 DOI: 10.1111/j.1365-313x.2009.04095.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Seeds play a fundamental role in colonization of the environment by spermatophytes, and seeds harvested from crops are the main food source for human beings. Knowledge of seed biology is therefore important for both fundamental and applied issues. This review on seed biology illustrates the important progress made in the field of Arabidopsis seed research over the last decade. Access to 'omics' tools, including the inventory of genes deduced from sequencing of the Arabidopsis genome, has speeded up the analysis of biological functions operating in seeds. This review covers the following processes: seed and seed coat development, seed reserve accumulation, seed dormancy and seed germination. We present new insights in these various fields and describe ongoing biotechnology approaches to improve seed characteristics in crops.
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Affiliation(s)
- Helen North
- INRA, Seed Biology Laboratory, Institut Jean Pierre Bourgin (IJPB), UMR 204 INRA/AgroParisTech, Versailles cedex, France
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73
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Ohto MA, Floyd SK, Fischer RL, Goldberg RB, Harada JJ. Effects of APETALA2 on embryo, endosperm, and seed coat development determine seed size in Arabidopsis. SEXUAL PLANT REPRODUCTION 2009. [PMID: 20033449 DOI: 10.1007/s00497-009-0116-111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Arabidopsis APETALA2 (AP2) controls seed mass maternally, with ap2 mutants producing larger seeds than wild type. Here, we show that AP2 influences development of the three major seed compartments: embryo, endosperm, and seed coat. AP2 appears to have a significant effect on endosperm development. ap2 mutant seeds undergo an extended period of rapid endosperm growth early in development relative to wild type. This early expanded growth period in ap2 seeds is associated with delayed endosperm cellularization and overgrowth of the endosperm central vacuole. The subsequent period of moderate endosperm growth is also extended in ap2 seeds largely due to persistent cell divisions at the endosperm periphery. The effect of AP2 on endosperm development is mediated by different mechanisms than parent-of-origin effects on seed size observed in interploidy crosses. Seed coat development is affected; integument cells of ap2 mutants are more elongated than wild type. We conclude that endosperm overgrowth and/or integument cell elongation create a larger postfertilization embryo sac into which the ap2 embryo can grow. Morphological development of the embryo is initially delayed in ap2 compared with wild-type seeds, but ap2 embryos become larger than wild type after the bent-cotyledon stage of development. ap2 embryos are able to fill the enlarged postfertilization embryo sac, because they undergo extended periods of cell proliferation and seed filling. We discuss potential mechanisms by which maternally acting AP2 influences development of the zygotic embryo and endosperm to repress seed size.
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Affiliation(s)
- Masa-aki Ohto
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA 95616, USA
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74
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Srivastava AC, Dasgupta K, Ajieren E, Costilla G, McGarry RC, Ayre BG. Arabidopsis plants harbouring a mutation in AtSUC2, encoding the predominant sucrose/proton symporter necessary for efficient phloem transport, are able to complete their life cycle and produce viable seed. ANNALS OF BOTANY 2009; 104:1121-8. [PMID: 19789176 PMCID: PMC2766205 DOI: 10.1093/aob/mcp215] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2009] [Revised: 07/21/2009] [Accepted: 07/23/2009] [Indexed: 05/18/2023]
Abstract
BACKGROUND AND AIMS AtSUC2 encodes a sucrose/proton symporter that localizes throughout the collection and transport phloem and is necessary for efficient transport of sucrose from source to sink tissues in Arabidopsis thaliana. Plants harbouring homozygous AtSUC2 null alleles accumulate sugar, starch, and anthocyanin in mature leaves, have severely delayed development and stunted growth and, in previous studies, failed to complete their life cycle by producing viable seed. METHODS An AtSUC2 allele with a T-DNA insertion in the second intron was analysed. Full-length transcript from this allele is not produced, and a truncated protein translated from sequences upstream of the insertion site did not catalyse sucrose uptake into yeast, supporting the contention that this is a null allele. Mutant plants were grown in a growth chamber with a diurnal light/dark cycle, and growth patterns recorded. KEY RESULTS This allele (SALK_038124, designated AtSUC2-4) has the hallmarks of previously described null alleles but, despite compromised carbon partitioning and growth, produces viable seeds. The onset of flowering was chronologically delayed but occurred at the same point in the plastochron index as wild type. CONCLUSIONS AtSUC2 is important for phloem loading and is therefore fundamental to phloem transport and plant productivity, but plants can complete their life cycle and produce viable seed in its absence. Arabidopsis appears to have mechanisms for mobilizing reduced carbon from the phloem into developing seeds independent of AtSUC2.
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Affiliation(s)
| | | | | | | | | | - Brian G. Ayre
- University of North Texas, Department of Biological Sciences, 1155 Union Circle #305220, Denton TX 76203-5017, USA
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75
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Melkus G, Rolletschek H, Radchuk R, Fuchs J, Rutten T, Wobus U, Altmann T, Jakob P, Borisjuk L. The metabolic role of the legume endosperm: a noninvasive imaging study. PLANT PHYSIOLOGY 2009; 151:1139-54. [PMID: 19748915 PMCID: PMC2773074 DOI: 10.1104/pp.109.143974] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Accepted: 09/08/2009] [Indexed: 05/18/2023]
Abstract
Although essential for normal seed development in the legumes, the metabolic role of the endosperm remains uncertain. We designed noninvasive nuclear magnetic resonance tools for the in vivo study of key metabolites in the transient liquid endosperm of intact pea (Pisum sativum) seeds. The steady-state levels of sucrose, glutamine, and alanine could be monitored and their distribution within the embryo sac visualized. Seed structure was digitalized as a three-dimensional model, providing volume information for distinct seed organs. The nuclear magnetic resonance method, combined with laser microdissection, isotope labeling, in situ hybridization, and electron microscopy, was used to contrast the wild-type endosperm with that of a mutant in which embryo growth is retarded. Expression of sequences encoding amino acid and sucrose transporters was up-regulated earlier in the endosperm than in the embryo, and this activity led to the accumulation of soluble metabolites in the endosperm vacuole. The endosperm provides a temporary source of nutrition, permits space for embryo growth, and acts as a buffer between the maternal organism and its offspring. The concentration of sucrose in the endosperm vacuole is developmentally controlled, while the total amount accumulated depends on the growth of the embryo. The endosperm concentration of glutamine is a limiting factor for protein storage. The properties of the endosperm ensure that the young embryo develops within a homeostatic environment, necessary to sustain embryogenesis. We argue for a degree of metabolite-mediated control exerted by the endosperm on the growth of, and assimilate storage by, the embryo.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Ljudmilla Borisjuk
- University of Würzburg, Institute of Experimental Physics 5, 97074 Wuerzburg, Germany (G.M., J.F., P.J.); and Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung, 06466 Gatersleben, Germany (H.R., R.R., T.R., U.W., T.A., L.B.)
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76
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Ohto MA, Floyd SK, Fischer RL, Goldberg RB, Harada JJ. Effects of APETALA2 on embryo, endosperm, and seed coat development determine seed size in Arabidopsis. ACTA ACUST UNITED AC 2009; 22:277-89. [PMID: 20033449 PMCID: PMC2796121 DOI: 10.1007/s00497-009-0116-1] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2009] [Accepted: 10/01/2009] [Indexed: 11/27/2022]
Abstract
Arabidopsis APETALA2 (AP2) controls seed mass maternally, with ap2 mutants producing larger seeds than wild type. Here, we show that AP2 influences development of the three major seed compartments: embryo, endosperm, and seed coat. AP2 appears to have a significant effect on endosperm development. ap2 mutant seeds undergo an extended period of rapid endosperm growth early in development relative to wild type. This early expanded growth period in ap2 seeds is associated with delayed endosperm cellularization and overgrowth of the endosperm central vacuole. The subsequent period of moderate endosperm growth is also extended in ap2 seeds largely due to persistent cell divisions at the endosperm periphery. The effect of AP2 on endosperm development is mediated by different mechanisms than parent-of-origin effects on seed size observed in interploidy crosses. Seed coat development is affected; integument cells of ap2 mutants are more elongated than wild type. We conclude that endosperm overgrowth and/or integument cell elongation create a larger postfertilization embryo sac into which the ap2 embryo can grow. Morphological development of the embryo is initially delayed in ap2 compared with wild-type seeds, but ap2 embryos become larger than wild type after the bent-cotyledon stage of development. ap2 embryos are able to fill the enlarged postfertilization embryo sac, because they undergo extended periods of cell proliferation and seed filling. We discuss potential mechanisms by which maternally acting AP2 influences development of the zygotic embryo and endosperm to repress seed size.
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Affiliation(s)
- Masa-aki Ohto
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA 95616, USA
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77
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Dusotoit-Coucaud A, Brunel N, Kongsawadworakul P, Viboonjun U, Lacointe A, Julien JL, Chrestin H, Sakr S. Sucrose importation into laticifers of Hevea brasiliensis, in relation to ethylene stimulation of latex production. ANNALS OF BOTANY 2009; 104:635-47. [PMID: 19567416 PMCID: PMC2729633 DOI: 10.1093/aob/mcp150] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
BACKGROUND AND AIMS The major economic product of Hevea brasiliensis is a rubber-containing cytoplasm (latex), which flows out of laticifers (latex cells) when the bark is tapped. The latex yield is stimulated by ethylene. Sucrose, the unique precursor of rubber synthesis, must cross the plasma membrane through specific sucrose transporters before being metabolized in the laticifers. The relative importance of sucrose transporters in determining latex yield is unknown. Here, the effects of ethylene (by application of Ethrel on sucrose transporter gene expression in the inner bark tissues and latex cells of H. brasiliensis are described. METHODS Experiments, including cloning sucrose transporters, real time RT-PCR and in situ hybridization, were carried out on virgin (untapped) trees, treated or untreated with the latex yield stimulant Ethrel. KEY RESULTS Seven putative full-length cDNAs of sucrose transporters were cloned from a latex-specific cDNA library. These transporters belong to all SUT (sucrose transporter) groups and differ by their basal gene expression in latex and inner soft bark, with a predominance of HbSUT1A and HbSUT1B. Of these sucrose transporters, only HbSUT1A and HbSUT2A were distinctly increased by ethylene. Moreover, this increase was shown to be specific to laticifers and to ethylene application. CONCLUSION The data and all previous information on sucrose transport show that HbSUT1A and HbSUT2A are related to the increase in sucrose import into laticifers, required for the stimulation of latex yield by ethylene in virgin trees.
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Affiliation(s)
- Anaïs Dusotoit-Coucaud
- UMR 547 PIAF, INRA, Université Blaise Pascal, 24 avenue des Landais, 63177 Aubière Cedex, France
| | - Nicole Brunel
- UMR 547 PIAF, INRA, Université Blaise Pascal, 24 avenue des Landais, 63177 Aubière Cedex, France
| | - Panida Kongsawadworakul
- Department of Plant Science, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand
| | - Unchera Viboonjun
- Department of Plant Science, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand
| | - André Lacointe
- UMR 547 PIAF, INRA, Université Blaise Pascal, 24 avenue des Landais, 63177 Aubière Cedex, France
| | - Jean-Louis Julien
- UMR 547 PIAF, INRA, Université Blaise Pascal, 24 avenue des Landais, 63177 Aubière Cedex, France
| | - Hervé Chrestin
- Department of Plant Science, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand
- Institut de Recherche pour le Developpement (IRD), UR 060 CLIFA/CEFE-CNRS, 1919 route de Mende, F34293, Montpellier Cedex 5, France
| | - Soulaïman Sakr
- UMR 547 PIAF, INRA, Université Blaise Pascal, 24 avenue des Landais, 63177 Aubière Cedex, France
- Agrocampus Ouest, Centre d'Angers, UMR SAGAH, IFR QUASAV 149, 2 rue le Nôtre, 49045 Angers Cedex, France
- For correspondence. E-mail
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Baud S, Dichow NR, Kelemen Z, d'Andréa S, To A, Berger N, Canonge M, Kronenberger J, Viterbo D, Dubreucq B, Lepiniec L, Chardot T, Miquel M. Regulation of HSD1 in seeds of Arabidopsis thaliana. PLANT & CELL PHYSIOLOGY 2009; 50:1463-78. [PMID: 19542545 DOI: 10.1093/pcp/pcp092] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The hydroxysteroid dehydrogenase HSD1, identified in the proteome of oil bodies from mature Arabidopsis seeds, is encoded by At5g50600 and At5g50700, two gene copies anchored on a duplicated region of chromosome 5. Using a real-time quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) approach, the accumulation of HSD1 mRNA was shown to be specifically and highly induced in oil-accumulating tissues of maturing seeds. HSD1 mRNA disappeared during germination. The activity of HSD1 promoter and the localization of HSD1 transcripts by in situ hybridization were consistent with this pattern. A complementary set of molecular and genetic analyses showed that HSD1 is a target of LEAFY COTYLEDON2, a transcriptional regulator able to bind the promoter of HSD1. Immunoblot analyses and immunolocalization experiments using anti-AtHSD1 antibodies established that the pattern of HSD1 deposition faithfully reflected mRNA accumulation. At the subcellular level, the study of HSD1:GFP fusion proteins showed the targeting of HSD1 to the surface of oil bodies. Transgenic lines overexpressing HSD1 were then obtained to test the importance of proper transcriptional regulation of HSD1 in seeds. Whereas no impact on oil accumulation could be detected, transgenic seeds exhibited lower cold and light requirements to break dormancy, germinate and mobilize storage lipids. Interestingly, overexpressors of HSD1 over-accumulated HSD1 protein in seeds but not in vegetative organs, suggesting that post-transcriptional regulations exist that prevent HSD1 accumulation in tissues deprived of oil bodies.
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Affiliation(s)
- Sébastien Baud
- Institut Jean-Pierre Bourgin, UMR Biologie des semences, INRA/AgroParisTech, F-78000 Versailles, France
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Song LI, Zhou XY, Li LI, Xue LJ, Yang XI, Xue HW. Genome-wide analysis revealed the complex regulatory network of brassinosteroid effects in photomorphogenesis. MOLECULAR PLANT 2009; 2:755-772. [PMID: 19825654 DOI: 10.1093/mp/ssp039] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Light and brassinosteroids (BRs) have been proved to be crucial in regulating plant growth and development; however, the mechanism of how they synergistically function is still largely unknown. To explore the underlying mechanisms in photomorphogenesis, genome-wide analyses were carried out through examining the gene expressions of the dark-grown WT or BR biosynthesis-defective mutant det2 seedlings in the presence of light stimuli or exogenous Brassinolide (BL). Results showed that BR deficiency stimulates, while BL treatment suppresses, the expressions of light-responsive genes and photomorphogenesis, confirming the negative effects of BR in photomorphogenesis. This is consistent with the specific effects of BR on the expression of genes involved in cell wall modification, cellular metabolism and energy utilization during dark-light transition. Further analysis revealed that hormone biosynthesis and signaling-related genes, especially those of auxin, were altered under BL treatment or light stimuli, indicating that BR may modulate photomorphogenesis through synergetic regulation with other hormones. Additionally, suppressed ubiquitin-cycle pathway during light-dark transition hinted the presence of a complicated network among light, hormone, and protein degradation. The study provides the direct evidence of BR effects in photomorphogenesis and identified the genes involved in BR and light signaling pathway, which will help to elucidate the molecular mechanism of plant photomorphogenesis.
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MESH Headings
- Arabidopsis/drug effects
- Arabidopsis/genetics
- Arabidopsis/growth & development
- Arabidopsis/metabolism
- Arabidopsis/radiation effects
- Arabidopsis Proteins/genetics
- Arabidopsis Proteins/physiology
- Brassinosteroids
- Cholestanols/metabolism
- Cholestanols/pharmacology
- Chromatin Immunoprecipitation
- Cluster Analysis
- Gene Expression Regulation, Plant/drug effects
- Gene Expression Regulation, Plant/radiation effects
- Genome, Plant/genetics
- Genome-Wide Association Study
- Light
- Morphogenesis/drug effects
- Morphogenesis/radiation effects
- Plants, Genetically Modified/drug effects
- Plants, Genetically Modified/genetics
- Plants, Genetically Modified/growth & development
- Plants, Genetically Modified/radiation effects
- Promoter Regions, Genetic
- Reverse Transcriptase Polymerase Chain Reaction
- Signal Transduction/drug effects
- Signal Transduction/radiation effects
- Steroids, Heterocyclic/metabolism
- Steroids, Heterocyclic/pharmacology
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Affiliation(s)
- L I Song
- National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, 200032 Shanghai, China
| | - Xiao-Yi Zhou
- National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, 200032 Shanghai, China
| | - L I Li
- National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, 200032 Shanghai, China
| | - Liang-Jiao Xue
- National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, 200032 Shanghai, China
| | - X I Yang
- National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, 200032 Shanghai, China
| | - Hong-Wei Xue
- National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, 200032 Shanghai, China.
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80
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Braun DM, Slewinski TL. Genetic control of carbon partitioning in grasses: roles of sucrose transporters and tie-dyed loci in phloem loading. PLANT PHYSIOLOGY 2009; 149:71-81. [PMID: 19126697 PMCID: PMC2613709 DOI: 10.1104/pp.108.129049] [Citation(s) in RCA: 126] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2008] [Accepted: 10/19/2008] [Indexed: 05/18/2023]
Affiliation(s)
- David M Braun
- Department of Biology, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
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81
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Lalonde S, Frommer WB. Mendel's bequest advanced the understanding of regulatory systems for controlling sugar supply to developing plant embryos. JOURNAL OF EXPERIMENTAL BOTANY 2009; 60:1-3. [PMID: 19213720 DOI: 10.1093/jxb/ern358] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
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82
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Joët T, Laffargue A, Salmona J, Doulbeau S, Descroix F, Bertrand B, de Kochko A, Dussert S. Metabolic pathways in tropical dicotyledonous albuminous seeds: Coffea arabica as a case study. THE NEW PHYTOLOGIST 2009; 182:146-162. [PMID: 19207685 PMCID: PMC2713855 DOI: 10.1111/j.1469-8137.2008.02742.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2008] [Accepted: 11/28/2008] [Indexed: 05/18/2023]
Abstract
* The genomic era facilitates the understanding of how transcriptional networks are interconnected to program seed development and filling. However, to date, little information is available regarding dicot seeds with a transient perisperm and a persistent, copious endosperm. Coffea arabica is the subject of increasing genomic research and is a model for nonorthodox albuminous dicot seeds of tropical origin. * The aim of this study was to reconstruct the metabolic pathways involved in the biosynthesis of the main coffee seed storage compounds, namely cell wall polysaccharides, triacylglycerols, sucrose, and chlorogenic acids. For this purpose, we integrated transcriptomic and metabolite analyses, combining real-time RT-PCR performed on 137 selected genes (of which 79 were uncharacterized in Coffea) and metabolite profiling. * Our map-drawing approach derived from model plants enabled us to propose a rationale for the peculiar traits of the coffee endosperm, such as its unusual fatty acid composition, remarkable accumulation of chlorogenic acid and cell wall polysaccharides. * Comparison with the developmental features of exalbuminous seeds described in the literature revealed that the two seed types share important regulatory mechanisms for reserve biosynthesis, independent of the origin and ploidy level of the storage tissue.
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Affiliation(s)
- Thierry Joët
- IRD, UMR DIA-PC, Pôle de Protection des Plantes97410, Saint Pierre, La Réunion, France
| | | | - Jordi Salmona
- IRD, UMR DIA-PC, Pôle de Protection des Plantes97410, Saint Pierre, La Réunion, France
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83
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Day RC, Herridge RP, Ambrose BA, Macknight RC. Transcriptome analysis of proliferating Arabidopsis endosperm reveals biological implications for the control of syncytial division, cytokinin signaling, and gene expression regulation. PLANT PHYSIOLOGY 2008; 148:1964-84. [PMID: 18923020 PMCID: PMC2593665 DOI: 10.1104/pp.108.128108] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2008] [Accepted: 10/06/2008] [Indexed: 05/18/2023]
Abstract
During the early stages of seed development, Arabidopsis (Arabidopsis thaliana) endosperm is syncytial and proliferates rapidly through repeated rounds of mitosis without cytokinesis. This stage of endosperm development is important in determining final seed size and is a model for studying aspects of cellular and molecular biology, such as the cell cycle and genomic imprinting. However, the small size of the Arabidopsis seed makes high-throughput molecular analysis of the early endosperm technically difficult. Laser capture microdissection enabled high-resolution transcript analysis of the syncytial stage of Arabidopsis endosperm development at 4 d after pollination. Analysis of Gene Ontology representation revealed a developmental program dominated by the expression of genes associated with cell cycle, DNA processing, chromatin assembly, protein synthesis, cytoskeleton- and microtubule-related processes, and cell/organelle biogenesis and organization. Analysis of core cell cycle genes implicates particular gene family members as playing important roles in controlling syncytial cell division. Hormone marker analysis indicates predominance for cytokinin signaling during early endosperm development. Comparisons with publicly available microarray data revealed that approximately 800 putative early seed-specific genes were preferentially expressed in the endosperm. Early seed expression was confirmed for 71 genes using quantitative reverse transcription-polymerase chain reaction, with 27 transcription factors being confirmed as early seed specific. Promoter-reporter lines confirmed endosperm-preferred expression at 4 d after pollination for five transcription factors, which validates the approach and suggests important roles for these genes during early endosperm development. In summary, the data generated provide a useful resource providing novel insight into early seed development and identify new target genes for further characterization.
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Affiliation(s)
- Robert C Day
- Department of Biochemistry, University of Otago, Dunedin 9054, New Zealand
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84
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Yang S, Johnston N, Talideh E, Mitchell S, Jeffree C, Goodrich J, Ingram G. The endosperm-specific ZHOUPI gene of Arabidopsis thaliana regulates endosperm breakdown and embryonic epidermal development. Development 2008; 135:3501-9. [DOI: 10.1242/dev.026708] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
During Arabidopsis seed development, the growing embryo invades and consumes the surrounding endosperm tissue. The signalling pathways that coordinate the separation of the embryo from the endosperm and the concomitant breakdown of the endosperm are poorly understood. We have identified a novel bHLH transcription factor, ZHOUPI (ZOU), which mediates these processes. ZOU is expressed exclusively in the endosperm of developing seeds. It is activated in the central cell immediately after fertilization and is initially expressed uniformly in endosperm, subsequently resolving to the embryo surrounding region (ESR). However, zou mutant embryos have defects in cuticle formation and in epidermal cell adhesion,suggesting that ZOU functions non-autonomously to regulate embryonic development. In addition, the endosperm of zou mutant seeds fails to separate from the embryo, restricting embryo expansion and resulting in the production of shrivelled collapsed seeds. zou seeds retain more endosperm than do wild-type seeds at maturity, suggesting that ZOUalso controls endosperm breakdown. We identify several target genes whose expression in the ESR is regulated by ZOU. These include ABNORMAL LEAF SHAPE1, which encodes a subtilisin-like protease previously shown to have a similar role to ZOU in regulating endosperm adhesion and embryonic epidermal development. However, expression of several other ESR-specific genes is independent of ZOU. Therefore, ZOU is not a general regulator of endosperm patterning, but rather controls specific signalling pathways that coordinate embryo invasion and breakdown of surrounding endosperm tissues.
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Affiliation(s)
- Suxin Yang
- Institute of Molecular Plant Sciences, School of Biology, University of Edinburgh, Rutherford Building, Mayfield Road, Edinburgh EH9 3JH, UK
| | - Niamh Johnston
- Institute of Molecular Plant Sciences, School of Biology, University of Edinburgh, Rutherford Building, Mayfield Road, Edinburgh EH9 3JH, UK
| | - Edmund Talideh
- Institute of Molecular Plant Sciences, School of Biology, University of Edinburgh, Rutherford Building, Mayfield Road, Edinburgh EH9 3JH, UK
| | - Steve Mitchell
- Institute of Molecular Plant Sciences, School of Biology, University of Edinburgh, Rutherford Building, Mayfield Road, Edinburgh EH9 3JH, UK
| | - Chris Jeffree
- Institute of Molecular Plant Sciences, School of Biology, University of Edinburgh, Rutherford Building, Mayfield Road, Edinburgh EH9 3JH, UK
| | - Justin Goodrich
- Institute of Molecular Plant Sciences, School of Biology, University of Edinburgh, Rutherford Building, Mayfield Road, Edinburgh EH9 3JH, UK
| | - Gwyneth Ingram
- Institute of Molecular Plant Sciences, School of Biology, University of Edinburgh, Rutherford Building, Mayfield Road, Edinburgh EH9 3JH, UK
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85
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Morley-Smith ER, Pike MJ, Findlay K, Köckenberger W, Hill LM, Smith AM, Rawsthorne S. The transport of sugars to developing embryos is not via the bulk endosperm in oilseed rape seeds. PLANT PHYSIOLOGY 2008; 147:2121-30. [PMID: 18562765 PMCID: PMC2492605 DOI: 10.1104/pp.108.124644] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2008] [Accepted: 06/13/2008] [Indexed: 05/18/2023]
Abstract
The fate of sucrose (Suc) supplied via the phloem to developing oilseed rape (Brassica napus) seeds has been investigated by supplying [(14)C]Suc to pedicels of detached, developing siliques. The method gives high, sustained rates of lipid synthesis in developing embryos within the silique comparable with those on the intact plant. At very early developmental stages (3 d after anthesis), the liquid fraction that occupies most of the interior of the seed has a very high hexose-to-Suc ratio and [(14)C]Suc entering the seeds is rapidly converted to hexoses. Between 3 and 12 d after anthesis, the hexose-to-Suc ratio of the liquid fraction of the seed remains high, but the fraction of [(14)C]Suc converted to hexose falls dramatically. Instead, most of the [(14)C]Suc entering the seed is rapidly converted to products in the growing embryo. These data, together with light and nuclear magnetic resonance microscopy, reveal complex compartmentation of sugar metabolism and transport within the seed during development. The bulk of the sugar in the liquid fraction of the seed is probably contained within the central vacuole of the endosperm. This sugar is not in contact with the embryo and is not on the path taken by carbon from the phloem to the embryo. These findings have important implications for the sugar switch model of embryo development and for understanding the relationship between the embryo and the surrounding endosperm.
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Affiliation(s)
- Edward R Morley-Smith
- Department of Metabolic Biology , John Innes Centre, Norwich NR4 7UH, United Kingdom
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86
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Kondou Y, Nakazawa M, Kawashima M, Ichikawa T, Yoshizumi T, Suzuki K, Ishikawa A, Koshi T, Matsui R, Muto S, Matsui M. RETARDED GROWTH OF EMBRYO1, a new basic helix-loop-helix protein, expresses in endosperm to control embryo growth. PLANT PHYSIOLOGY 2008; 147:1924-35. [PMID: 18567831 PMCID: PMC2492639 DOI: 10.1104/pp.108.118364] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2008] [Accepted: 06/02/2008] [Indexed: 05/18/2023]
Abstract
We have isolated two dominant mutants from screening approximately 50,000 RIKEN activation-tagging lines that have short inflorescence internodes. The activation T-DNAs were inserted near a putative basic helix-loop-helix (bHLH) gene and expression of this gene was increased in the mutant lines. Overexpression of this bHLH gene produced the original mutant phenotype, indicating it was responsible for the mutants. Specific expression was observed during seed development. The loss-of-function mutation of the RETARDED GROWTH OF EMBRYO1 (RGE1) gene caused small and shriveled seeds. The embryo of the loss-of-function mutant showed retarded growth after the heart stage although abnormal morphogenesis and pattern formation of the embryo and endosperm was not observed. We named this bHLH gene RGE1. RGE1 expression was determined in endosperm cells using the beta-glucuronidase reporter gene and reverse transcription-polymerase chain reaction. Microarray and real-time reverse transcription-polymerase chain reaction analysis showed specific down-regulation of putative GDSL motif lipase genes in the rge1-1 mutant, indicating possible involvement of these genes in seed morphology. These data suggest that RGE1 expression in the endosperm at the heart stage of embryo development plays an important role in controlling embryo growth.
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Affiliation(s)
- Youichi Kondou
- Plant Functional Genomics Research Group, RIKEN Plant Science Center, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
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87
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Baud S, Dubreucq B, Miquel M, Rochat C, Lepiniec L. Storage reserve accumulation in Arabidopsis: metabolic and developmental control of seed filling. THE ARABIDOPSIS BOOK 2008; 6:e0113. [PMID: 22303238 PMCID: PMC3243342 DOI: 10.1199/tab.0113] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
In the life cycle of higher plants, seed development is a key process connecting two distinct sporophytic generations. Seed development can be divided into embryo morphogenesis and seed maturation. An essential metabolic function of maturing seeds is the deposition of storage compounds that are mobilised to fuel post-germinative seedling growth. Given the importance of seeds for food and animal feed and considering the tremendous interest in using seed storage products as sustainable industrial feedstocks to replace diminishing fossil reserves, understanding the metabolic and developmental control of seed filling constitutes a major focus of plant research. Arabidopsis thaliana is an oilseed species closely related to the agronomically important Brassica oilseed crops. The main storage compounds accumulated in seeds of A. thaliana consist of oil stored as triacylglycerols (TAGs) and seed storage proteins (SSPs). Extensive tools developed for the molecular dissection of A. thaliana development and metabolism together with analytical and cytological procedures adapted for very small seeds have led to a good description of the biochemical pathways producing storage compounds. In recent years, studies using these tools have shed new light on the intricate regulatory network controlling the seed maturation process. This network involves sugar and hormone signalling together with a set of developmentally regulated transcription factors. Although much remains to be elucidated, the framework of the regulatory system controlling seed filling is coming into focus.
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Affiliation(s)
- Sébastien Baud
- Seed Biology Laboratory, Institut Jean-Pierre Bourgin (IJPB), UMR 204, INRA, AgroParisTech, 78000 Versailles, France
| | - Bertrand Dubreucq
- Seed Biology Laboratory, Institut Jean-Pierre Bourgin (IJPB), UMR 204, INRA, AgroParisTech, 78000 Versailles, France
| | - Martine Miquel
- Seed Biology Laboratory, Institut Jean-Pierre Bourgin (IJPB), UMR 204, INRA, AgroParisTech, 78000 Versailles, France
| | - Christine Rochat
- Seed Biology Laboratory, Institut Jean-Pierre Bourgin (IJPB), UMR 204, INRA, AgroParisTech, 78000 Versailles, France
| | - Loïc Lepiniec
- Seed Biology Laboratory, Institut Jean-Pierre Bourgin (IJPB), UMR 204, INRA, AgroParisTech, 78000 Versailles, France
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88
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Fallahi H, Scofield GN, Badger MR, Chow WS, Furbank RT, Ruan YL. Localization of sucrose synthase in developing seed and siliques of Arabidopsis thaliana reveals diverse roles for SUS during development. JOURNAL OF EXPERIMENTAL BOTANY 2008; 59:3283-95. [PMID: 18635527 PMCID: PMC2529237 DOI: 10.1093/jxb/ern180] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2008] [Revised: 06/10/2008] [Accepted: 06/13/2008] [Indexed: 05/18/2023]
Abstract
This study investigated the roles of sucrose synthase (SUS) in developing seeds and siliques of Arabidopsis thaliana. Enzyme activity assays showed that SUS activity was highest in developing whole siliques and young rosette leaves compared with other tissues including mature leaves, stems, and flowers. Surprisingly, quantitative PCR analyses revealed little correlation between SUS activity and transcript expression, which indicated the importance of examining the role of SUS at the protein level. Therefore, immunolocalization was performed over a developmental time course to determine the previously unreported cellular localization of SUS in Arabidopsis seed and silique tissues. At 3 d and 10 d after flowering (daf), SUS protein localized to the silique wall, seed coat, funiculus, and endosperm. By 13 daf, SUS protein was detected in the embryo and aleurone layer, but was absent from the seed coat and funiculus. Starch grains were also present in the seed coat at 3 and 10 daf, but were absent at 13 daf. Co-localization of SUS protein and starch grains in the seed coat at 3 and 10 daf indicates that SUS may be involved in temporary starch deposition during the early stages of seed development, whilst in the later stages SUS metabolizes sucrose in the embryo and cotyledon. Within the silique wall, SUS localized specifically to the companion cells, indicating that SUS activity may be required to provide energy for phloem transport activities in the silique wall. The results highlight the diverse roles that SUS may play during the development of silique and seed in Arabidopsis.
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Affiliation(s)
- Hossein Fallahi
- CSIRO Plant Industry, PO Box 1600, Canberra, ACT 2601, Australia
- RSBS, Australian National University, PO Box 475, Canberra, ACT 2601, Australia
| | | | - Murray R. Badger
- RSBS, Australian National University, PO Box 475, Canberra, ACT 2601, Australia
| | - Wah Soon Chow
- RSBS, Australian National University, PO Box 475, Canberra, ACT 2601, Australia
| | | | - Yong-Ling Ruan
- School of Environmental and Life Sciences, the University of Newcastle, NSW 2308, Australia
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89
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Ruan YL, Llewellyn DJ, Liu Q, Xu SM, Wu LM, Wang L, Furbank RT. Expression of sucrose synthase in the developing endosperm is essential for early seed development in cotton. FUNCTIONAL PLANT BIOLOGY : FPB 2008; 35:382-393. [PMID: 32688795 DOI: 10.1071/fp08017] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2008] [Accepted: 05/01/2008] [Indexed: 06/11/2023]
Abstract
Successful seed development requires coordinated interaction of the endosperm and embryo. In most dicotyledonous seeds, the endosperm is crushed and absorbed by the expanding embryo in the later stages of seed development. Little is known about the metabolic interaction between the two filial tissues early in seed development. We examined the potential role of sucrose synthase (Sus) in the endosperm development of cotton. Sus was immunologically localised in the cellularising endosperm, but not in the heart-stage embryo at 10 days after anthesis. The activities of Sus and acid invertase were significantly higher in the endosperm than in the young embryos, which corresponded to a steep concentration difference in hexoses between the endosperm and the embryo. This observation indicates a role for the endosperm in generating hexoses for the development of the two filial tissues. Interestingly, Sus expression and starch deposition were spatially separated in the seeds. Silencing the expression of Sus in the endosperm using an RNAi approach led to the arrest of early seed development. Histochemical analyses revealed a significant reduction in cellulose and callose in the deformed endosperm cells of the Sus-suppressed seed. The data indicate a critical role of Sus in early seed development through regulation of endosperm formation.
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Affiliation(s)
- Yong-Ling Ruan
- School of Environmental and Life Sciences, The University of Newcastle, Callaghan, NSW 2308, Australia
| | | | - Qing Liu
- CSIRO Plant Industry, GPO Box 1600, Canberra, ACT 2601, Australia
| | - Shou-Min Xu
- CSIRO Plant Industry, GPO Box 1600, Canberra, ACT 2601, Australia
| | - Li-Min Wu
- CSIRO Plant Industry, GPO Box 1600, Canberra, ACT 2601, Australia
| | - Lu Wang
- Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Robert T Furbank
- CSIRO Plant Industry, GPO Box 1600, Canberra, ACT 2601, Australia
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90
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Santos-Mendoza M, Dubreucq B, Baud S, Parcy F, Caboche M, Lepiniec L. Deciphering gene regulatory networks that control seed development and maturation in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2008; 54:608-20. [PMID: 18476867 DOI: 10.1111/j.1365-313x.2008.03461.x] [Citation(s) in RCA: 275] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Seeds represent the main source of nutrients for animals and humans, and knowledge of their biology provides tools for improving agricultural practices and managing genetic resources. There is also tremendous interest in using seeds as a sustainable alternative to fossil reserves for green chemistry. Seeds accumulate large amounts of storage compounds such as carbohydrates, proteins and oils. It would be useful for agro-industrial purposes to produce seeds that accumulate these storage compounds more specifically and at higher levels. The main metabolic pathways necessary for oil, starch or protein accumulation are well characterized. However, the overall regulation of partitioning between the various pathways remains unclear. Such knowledge could provide new molecular tools for improving the qualities of crop seeds (Focks and Benning, 1998, Plant Physiol. 118, 91). Studies to improve understanding of the genetic controls of seed development and metabolism therefore remain a key area of research. In the model plant Arabidopsis, genetic analyses have demonstrated that LEAFY COTYLEDON genes, namely LEC1, LEC2 and FUSCA3 (FUS3), are key transcriptional regulators of seed maturation, together with ABSCISIC ACID INSENSITIVE 3 (ABI3). Interestingly, LEC2, FUS3 and ABI3 are related proteins that all contain a 'B3' DNA-binding domain. In recent years, genetic and molecular studies have shed new light on the intricate regulatory network involving these regulators and their interactions with other factors such as LEC1, PICKLE, ABI5 or WRI1, as well as with sugar and hormonal signaling. Here, we summarize the most recent advances in our understanding of this complex regulatory network and its role in the control of seed maturation.
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Affiliation(s)
- Monica Santos-Mendoza
- INRA, AgroParitech, UMR204, Institut Jean-Pierre Bourgin (IJPB), Seed Biology Laboratory, 78026 Versailles Cedex, France
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91
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Aquea F, Arce-Johnson P. Identification of genes expressed during early somatic embryogenesis in Pinus radiata. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2008; 46:559-68. [PMID: 18406157 DOI: 10.1016/j.plaphy.2008.02.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2007] [Indexed: 05/22/2023]
Abstract
Analysis of cDNA-AFLPs was used to study gene expression underlying the early embryogenic process in the gymnosperm Pinus radiata. Somatic embryogenesis in this species was used as a model as it resulted in the generation of a large number of embryos at defined stages of development. The gene expression patterns of three embryogenic stages were compared with non-embryogenic cells. Fifty transcript-derived fragments (TDFs) that are upregulated and 32 TDFs that are down-regulated in the embryogenic stages were selected, sequenced and their homologies sought in the databases. Expression of a selected subset of differentially expressed genes was confirmed by RT-PCR and their levels of expression were quantified. Of the 50 up-regulated TDFs, 16 are homologous to genes encoding either known or putative proteins in higher plants, 19 are homologous to conifer ESTs and 15 did not show significant matches. Of the down-regulated TDFs, 8 are homologous to genes encoding either known or putative proteins, 20 are homologous to conifer ESTs and 4 of them did not show significant matches in DNA or protein sequence database. The known up-regulated genes were similar to genes involved in cellular metabolism and in the stress response and the known down-regulated genes were similar to genes involved in proteolysis, cell wall modification and signaling pathways. Their putative individual function is briefly reviewed based on published information, and the potential roles of these genes in embryo development are discussed.
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Affiliation(s)
- Felipe Aquea
- Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas. Pontificia Universidad Católica de Chile, P.O. Box 114-D, Santiago, Chile
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92
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Baud S, Wuillème S, Dubreucq B, de Almeida A, Vuagnat C, Lepiniec L, Miquel M, Rochat C. Function of plastidial pyruvate kinases in seeds of Arabidopsis thaliana. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2007; 52:405-19. [PMID: 17892448 DOI: 10.1111/j.1365-313x.2007.03232.x] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Pyruvate kinase (PK) catalyses the irreversible synthesis of pyruvate and ATP, which are both used in multiple biochemical pathways. These compounds are essential for sustained fatty acid production in the plastids of maturing Arabidopsis embryos. Using a real-time quantitative reverse transcriptase (RT)-PCR approach, the three genes encoding putative plastidial PKs (PKps) in Arabidopsis, namely PKp1 (At3g22960), PKp2 (At5g52920) and PKp3 (At1g32440), were shown to be ubiquitously expressed. However, only PKp1 and PKp2 exhibited significant expression in maturing seeds. The activity of PKp1 and PKp2 promoters was consistent with this pattern, and the study of the PKp1:GFP and PKp2:GFP fusion proteins confirmed the plastidial localization of these enzymes. To further investigate the function of these two PKp isoforms in seeds comprehensive functional analyses were carried out, including the cytological, biochemical and molecular characterization of two pkp1 and two pkp2 alleles, together with a pkp1pkp2 double mutant. The results obtained outlined the importance of these PKps for fatty acid synthesis and embryo development. Mutant seeds were depleted of oil, their fatty acid content was drastically modified, embryo elongation was retarded and, finally, seed germination was also affected. Together, these results provide interesting insights concerning the carbon fluxes leading to oil synthesis in maturing Arabidopsis seeds. The regulation of this metabolic network by the WRINKLED1 transcription factor is discussed, and emphasizes the role of plastidial metabolism and the importance of its tight regulation.
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Affiliation(s)
- Sébastien Baud
- Laboratoire de Biologie des Semences, IJPB, UMR204, INRA/AgroParisTech, F-78000 Versailles, France
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93
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Gutierrez L, Van Wuytswinkel O, Castelain M, Bellini C. Combined networks regulating seed maturation. TRENDS IN PLANT SCIENCE 2007; 12:294-300. [PMID: 17588801 DOI: 10.1016/j.tplants.2007.06.003] [Citation(s) in RCA: 188] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2007] [Revised: 03/22/2007] [Accepted: 06/06/2007] [Indexed: 05/16/2023]
Abstract
Seed maturation is an important phase of seed development during which embryo growth ceases, storage products accumulate, the protective tegument differentiates and tolerance to desiccation develops, leading to seed dormancy. The spatial and temporal regulation of all these processes requires the concerted action of several signaling pathways that integrate information from genetic programs, and both hormonal and metabolic signals. Recent genetic studies have identified some of the interactions that occur between four master regulators in Arabidopsis, increasing our knowledge of the control of the transcriptional program involved in seed maturation. Moreover, several recent breakthroughs have led to a better understanding of the role of abscisic acid signal modulation and the importance of metabolic regulation in the maternal to filial switch leading to the maturation phase.
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Affiliation(s)
- Laurent Gutierrez
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences SLU, 901 83 Umeå, Sweden.
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94
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Baud S, Mendoza MS, To A, Harscoët E, Lepiniec L, Dubreucq B. WRINKLED1 specifies the regulatory action of LEAFY COTYLEDON2 towards fatty acid metabolism during seed maturation in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2007; 50:825-38. [PMID: 17419836 DOI: 10.1111/j.1365-313x.2007.03092.x] [Citation(s) in RCA: 292] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The WRINKLED1 (WRI1) transcription factor has been shown to play a role of the utmost importance during oil accumulation in maturing seeds of Arabidopsis thaliana. However, little is known about the regulatory processes involved. In this paper, comprehensive functional analyses of three new mutants corresponding to null alleles of wri1 confirm that the induction of WRI1 is a prerequisite for fatty acid synthesis and is important for normal embryo development. The strong expression of WRI1 specifically detected at the onset of the maturation phase in oil-accumulating tissues of A. thaliana seeds is fully consistent with this function. Complementation experiments carried out with various seed-specific promoters emphasized the importance of a tight regulation of WRI1 expression for proper oil accumulation, raising the question of the factors controlling WRI1 transcription. Interestingly, molecular and genetic analyses using an inducible system demonstrated that WRI1 is a target of LEAFY COTYLEDON2 and is necessary for the regulatory action of LEC2 towards fatty acid metabolism. In addition to this, quantitative RT-PCR experiments suggested that several genes encoding enzymes of late glycolysis, the fatty acid synthesis pathway, and the biotin and lipoic acid biosynthetic pathways are targets of WRI1. Taken together, these results indicate new relationships in the regulatory model for the control of oil synthesis in maturing A. thaliana seeds. In addition, they exemplify how metabolic and developmental processes affecting the developing embryo can be coordinated at the molecular level.
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Affiliation(s)
- Sébastien Baud
- Laboratoire de Biologie des Semences, IJPB,UMR 204 INRA/AgroParis Tech, F-78026 Versailles, France
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95
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Zhang WH, Zhou Y, Dibley KE, Tyerman SD, Furbank RT, Patrick JW. Review: Nutrient loading of developing seeds. FUNCTIONAL PLANT BIOLOGY : FPB 2007; 34:314-331. [PMID: 32689358 DOI: 10.1071/fp06271] [Citation(s) in RCA: 113] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2006] [Accepted: 01/30/2007] [Indexed: 05/03/2023]
Abstract
Interest in nutrient loading of seeds is fuelled by its central importance to plant reproductive success and human nutrition. Rates of nutrient loading, imported through the phloem, are regulated by transport and transfer processes located in sources (leaves, stems, reproductive structures), phloem pathway and seed sinks. During the early phases of seed development, most control is likely to be imposed by a low conductive pathway of differentiating phloem cells serving developing seeds. Following the onset of storage product accumulation by seeds, and, depending on nutrient species, dominance of path control gives way to regulation by processes located in sources (nitrogen, sulfur, minor minerals), phloem path (transition elements) or seed sinks (sugars and major mineral elements, such as potassium). Nutrients and accompanying water are imported into maternal seed tissues and unloaded from the conducting sieve elements into an extensive post-phloem symplasmic domain. Nutrients are released from this symplasmic domain into the seed apoplasm by poorly understood membrane transport mechanisms. As seed development progresses, increasing volumes of imported phloem water are recycled back to the parent plant by process(es) yet to be discovered. However, aquaporins concentrated in vascular and surrounding parenchyma cells of legume seed coats could provide a gated pathway of water movement in these tissues. Filial cells, abutting the maternal tissues, take up nutrients from the seed apoplasm by membrane proteins that include sucrose and amino acid/H+ symporters functioning in parallel with non-selective cation channels. Filial demand for nutrients, that comprise the major osmotic species, is integrated with their release and phloem import by a turgor-homeostat mechanism located in maternal seed tissues. It is speculated that turgors of maternal unloading cells are sensed by the cytoskeleton and transduced by calcium signalling cascades.
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Affiliation(s)
- Wen-Hao Zhang
- Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, The Chinese Academy of Sciences, Beijing 100093, China
| | - Yuchan Zhou
- School of Environmental and Life Sciences, The University of Newcastle, Callaghan, NSW 2238, Australia
| | - Katherine E Dibley
- School of Environmental and Life Sciences, The University of Newcastle, Callaghan, NSW 2238, Australia
| | - Stephen D Tyerman
- School of Agriculture, Food and Wine, Adelaide University, Waite Campus, PMB #1, Glen Osmond, SA 5064, Australia
| | - Robert T Furbank
- CSIRO Plant Industry, GPO Box 1600, Canberra, ACT 2601, Australia
| | - John W Patrick
- School of Environmental and Life Sciences, The University of Newcastle, Callaghan, NSW 2238, Australia
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96
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Sauer N. Molecular physiology of higher plant sucrose transporters. FEBS Lett 2007; 581:2309-17. [PMID: 17434165 DOI: 10.1016/j.febslet.2007.03.048] [Citation(s) in RCA: 246] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2007] [Revised: 03/21/2007] [Accepted: 03/21/2007] [Indexed: 11/27/2022]
Abstract
Sucrose is the primary product of photosynthetic CO(2) fixation that is used for the distribution of assimilated carbon within higher plants. Its partitioning from the site of synthesis to different sites of storage, conversion into other storage compounds or metabolic degradation involves various steps of cell-to-cell movement and transport. Many of these steps occur within symplastic domains, i.e. sucrose moves passively cell-to-cell through plasmodesmata. Some essential steps, however, occur between symplastically isolated cells or tissues. In these cases, sucrose is transiently released into the apoplast and its cell-to-cell transport depends on the activity of plasma membrane-localized, energy dependent, H(+)-symporting carrier proteins. This paper reviews the current knowledge of sucrose transporter physiology and molecular biology.
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Affiliation(s)
- Norbert Sauer
- Molekulare Pflanzenphysiologie, FAU Erlangen-Nürnberg, Staudtstrasse 5, D-91058 Erlangen, Germany.
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97
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Day RC, McNoe L, Macknight RC. Evaluation of global RNA amplification and its use for high-throughput transcript analysis of laser-microdissected endosperm. INTERNATIONAL JOURNAL OF PLANT GENOMICS 2007; 2007:61028. [PMID: 18253465 PMCID: PMC1939914 DOI: 10.1155/2007/61028] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2006] [Revised: 01/13/2007] [Accepted: 01/22/2007] [Indexed: 05/18/2023]
Abstract
Laser microdissection (LM) provides a useful method for isolating specific cells or tissues from biological samples. Here, we adapted microdissection protocols to allow high-resolution transcript analysis of different tissues from developing Arabidopsis seed. Sufficient RNA ( approximately 50 ng) was extracted from endosperm tissue for RT-PCR. However, to obtain enough RNA for microarray analyses, it was necessary to amplify the RNA. PCR- and IVT-based amplification methods were investigated and several important technical aspects of amplification were identified (such as target truncation and alterations in signal intensity). We found that when starting from only 50 ng of RNA, amplification methods based on PCR and IVT produced sufficient product for reliable microarray hybridizations, with two-round IVT giving the best results. Microarray analyses, using endosperm-derived RNA amplified by two-round IVT, reproducibly identified endosperm enriched marker genes. Thus, when combined with RNA-amplification protocols, LM is a robust and reliable technique for high-throughput tissue-specific gene expression analysis.
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Affiliation(s)
- Robert C. Day
- Department of Biochemistry, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
| | - Les McNoe
- Genomics Facility, Department of Biochemistry, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
| | - Richard C. Macknight
- Department of Biochemistry, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
- *Richard C. Macknight:
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98
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Fait A, Angelovici R, Less H, Ohad I, Urbanczyk-Wochniak E, Fernie AR, Galili G. Arabidopsis seed development and germination is associated with temporally distinct metabolic switches. PLANT PHYSIOLOGY 2006; 142:839-54. [PMID: 16963520 PMCID: PMC1630763 DOI: 10.1104/pp.106.086694] [Citation(s) in RCA: 289] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
While the metabolic networks in developing seeds during the period of reserve accumulation have been extensively characterized, much less is known about those present during seed desiccation and subsequent germination. Here we utilized metabolite profiling, in conjunction with selective mRNA and physiological profiling to characterize Arabidopsis (Arabidopsis thaliana) seeds throughout development and germination. Seed maturation was associated with a significant reduction of most sugars, organic acids, and amino acids, suggesting their efficient incorporation into storage reserves. The transition from reserve accumulation to seed desiccation was associated with a major metabolic switch, resulting in the accumulation of distinct sugars, organic acids, nitrogen-rich amino acids, and shikimate-derived metabolites. In contrast, seed vernalization was associated with a decrease in the content of several of the metabolic intermediates accumulated during seed desiccation, implying that these intermediates might support the metabolic reorganization needed for seed germination. Concomitantly, the levels of other metabolites significantly increased during vernalization and were boosted further during germination sensu stricto, implying their importance for germination and seedling establishment. The metabolic switches during seed maturation and germination were also associated with distinct patterns of expression of genes encoding metabolism-associated gene products, as determined by semiquantitative reverse transcription-polymerase chain reaction and analysis of publicly available microarray data. When taken together our results provide a comprehensive picture of the coordinated changes in primary metabolism that underlie seed development and germination in Arabidopsis. They furthermore imply that the metabolic preparation for germination and efficient seedling establishment initiates already during seed desiccation and continues by additional distinct metabolic switches during vernalization and early germination.
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Affiliation(s)
- Aaron Fait
- Department of Plant Sciences, the Weizmann Institute of Science, 76100 Rehovot, Israel
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