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Charles S. Gasser - One of the best experts on this subject based on the ideXlab platform.
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Integument development in arabidopsis depends on interaction of yabby protein inner no outer with coactivators and corepressors
Genetics, 2017Co-Authors: Marissa K Simon, Thomas L Gallagher, Debra J. Skinner, Charles S. GasserAbstract:Arabidopsis thaliana INNER NO OUTER (INO) is a YABBY protein that is essential for the initiation and development of the outer Integument of ovules. Other YABBY proteins have been shown to be involved in both negative and positive regulation of expression of putative target genes. YABBY proteins have also been shown to interact with the corepressor LEUNIG (LUG) in several systems. In support of a repressive role for INO, we confirm that INO interacts with LUG and also find that INO directly interacts with SEUSS (SEU), a known corepressive partner of LUG. Further, we find that INO can directly interact with ADA2b/PROPORZ1 (PRZ1), a transcriptional coactivator that is known to interact with the histone acetyltransferase GENERAL CONTROL NONREPRESSIBLE PROTEIN 5 (GCN5, also known as HAG1). Mutations in LUG, SEU, and ADA2b/PRZ1 all lead to pleiotropic effects including a deficiency in the extension of the outer Integument. Additive and synergistic effects of ada2b/prz1 and lug mutations on outer Integument formation indicate that these two genes function independently to promote outer Integument growth. The ino mutation is epistatic to both lug and ada2b/prz1 in the outer Integument, and all three proteins are present in the nuclei of a common set of outer Integument cells. This is consistent with a model where INO utilizes these coregulator proteins to activate and repress separate sets of target genes. Other Arabidopsis YABBY proteins were shown to also form complexes with ADA2b/PRZ1, and have been previously shown to interact with SEU and LUG. Thus, interaction with these corepressors and coactivator may represent a general mechanism to explain the positive and negative activities of YABBY proteins in transcriptional regulation. The LUG, SEU, and ADA2b/PRZ1 proteins would also separately be recruited to targets of other transcription factors, consistent with their roles as general coregulators, explaining the pleiotropic effects not associated with YABBY function.
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ettin arf3 physically interacts with kanadi proteins to form a functional complex essential for Integument development and polarity determination in arabidopsis
Development, 2012Co-Authors: Dior R Kelley, Alexandra Arreola, Thomas L Gallagher, Charles S. GasserAbstract:KANADI (KAN) transcription factors promote abaxial cell fate throughout plant development and are required for organ formation during embryo, leaf, carpel and ovule development. ABERRANT TESTA SHAPE (ATS, or KAN4) is necessary during ovule development to maintain the boundary between the two ovule Integuments and to promote inner Integument growth. Yeast two-hybrid assays identified ETTIN (ETT, or AUXIN RESPONSE FACTOR 3) as a transcription factor that could physically interact with ATS. ATS and ETT were shown to physically interact in vivo in transiently transformed tobacco epidermal cells using bimolecular fluorescence complementation. ATS and ETT were found to share an overlapping expression pattern during Arabidopsis ovule development and loss of either gene resulted in congenital fusion of the Integuments and altered seed morphology. We hypothesize that in wild-type ovules a physical interaction between ATS and ETT allows these proteins to act in concert to define the boundary between Integument primordia. We further show protein-protein interaction in yeast between ETT and KAN1, a paralog of ATS. Thus, a direct physical association between ETT and KAN proteins underpins their previously described common role in polarity establishment and organogenesis. We propose that ETT-KAN protein complex(es) constitute part of an auxin-dependent regulatory module that plays a conserved role in a variety of developmental contexts.
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Expression of ovule and Integument‐associated genes in reduced ovules of Santalales
Evolution & Development, 2010Co-Authors: Ryan H Brown, Daniel L. Nickrent, Charles S. GasserAbstract:1Present address: National Small Grains Germplasm Research Facility, USDA-ARS, Aberdeen, ID 83210, USA SUMMARY Santalales comprise mainly parasitic plants including mistletoes and sandalwoods. Bitegmic ovules similar to those found in most other angiosperms are seen in many members of the order, but other members exhibit evolutionary reductions to the unitegmic and ategmic conditions. In some mistletoes, extreme reduction has resulted in the absence of emergent ovules such that embryo sacs appear to remain embedded in placental tissues. Three santalalean representatives (Comandra, Santalum, and Phoradendron), displaying unitegmic, and ategmic ovules, were studied. Observed ovule morphologies were consistent with published reports, including Phoradendron serotinum, which we interpret as having reduced ategmic ovules, consistent with earlier reports on this species. For further understanding of the nature of the ovule reductions we isolated orthologs of the Arabidopsis genes AIntegumentA (ANT) and BELL1 (BEL1), which are associated with ovule development in this species. We observed ovular expression of ANT and BEL1 in patterns largely resembling those seen in the Integumented ovules of Arabidopsis. These genes were found to be expressed in the Integument of unitegmic ovules and in the surface layers of ategmic ovules, and in some cases, expression of BEL1 was also observed in the surrounding carpel tissue. We hypothesize that ategmic ovules derive from a fusion of the Integuments with the nucellus or that the nucellus has taken on some of the characteristics confined to Integuments in ancestral species.
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Expression of ovule and Integument‐associated genes in reduced ovules of Santalales
Evolution & development, 2010Co-Authors: Ryan H Brown, Daniel L. Nickrent, Charles S. GasserAbstract:Santalales comprise mainly parasitic plants including mistletoes and sandalwoods. Bitegmic ovules similar to those found in most other angiosperms are seen in many members of the order, but other members exhibit evolutionary reductions to the unitegmic and ategmic conditions. In some mistletoes, extreme reduction has resulted in the absence of emergent ovules such that embryo sacs appear to remain embedded in placental tissues. Three santalalean representatives (Comandra, Santalum, and Phoradendron), displaying unitegmic, and ategmic ovules, were studied. Observed ovule morphologies were consistent with published reports, including Phoradendron serotinum, which we interpret as having reduced ategmic ovules, consistent with earlier reports on this species. For further understanding of the nature of the ovule reductions we isolated orthologs of the Arabidopsis genes AIntegumentA (ANT) and BELL1 (BEL1), which are associated with ovule development in this species. We observed ovular expression of ANT and BEL1 in patterns largely resembling those seen in the Integumented ovules of Arabidopsis. These genes were found to be expressed in the Integument of unitegmic ovules and in the surface layers of ategmic ovules, and in some cases, expression of BEL1 was also observed in the surrounding carpel tissue. We hypothesize that ategmic ovules derive from a fusion of the Integuments with the nucellus or that the nucellus has taken on some of the characteristics confined to Integuments in ancestral species.
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ABERRANT TESTA SHAPE encodes a KANADI family member, linking polarity determination to separation and growth of Arabidopsis ovule Integuments.
The Plant journal : for cell and molecular biology, 2006Co-Authors: Jessica Messmer Mcabee, Bernard A. Hauser, Theresa Hill, Debra J. Skinner, Anat Izhaki, Robert J. Meister, G. Venugopala Reddy, Elliot M. Meyerowitz, John L. Bowman, Charles S. GasserAbstract:The Arabidopsis aberrant testa shape (ats) mutant produces a single Integument instead of the two Integuments seen in wild-type ovules. Cellular anatomy and patterns of marker gene expression indicate that the single Integument results from congenital fusion of the two Integuments of the wild type. Isolation of the ATS locus showed it to encode a member of the KANADI (KAN) family of putative transcription factors, previously referred to as KAN4. ATS was expressed at the border between the two Integuments at the time of their initiation, with expression later confined to the abaxial layer of the inner Integument. In an inner no outer (ino) mutant background, where an outer Integument does not form, the ats mutation led to amorphous inner Integument growth. The kan1kan2 double mutant exhibits a similar amorphous growth of the outer Integument without affecting inner Integument growth. We hypothesize that ATS and KAN1/KAN2 play similar roles in the specification of polarity in the inner and outer Integuments, respectively, that parallel the known roles of KAN proteins in promoting abaxial identity during leaf development. INO and other members of the YABBY gene family have been hypothesized to have similar parallel roles in outer Integument and leaf development. Together, these two hypotheses lead us to propose a model for normal Integument growth that also explains the described mutant phenotypes.
Enrico Magnani - One of the best experts on this subject based on the ideXlab platform.
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GPI-anchored SKU5/SKS are maternally required for Integument development in Arabidopsis
2019Co-Authors: Ke Zhou, Elisa Fiume, Delphine De Vos, Enrico MagnaniAbstract:ABSTRACT Glycosylphosphatidylinositol-anchored proteins (GPI-APs) play crucial roles in various processes in eukaryotes. In Arabidopsis, SKS1, SKS2, SKS3 and SKU5 from SKU5/SKS gene family could encode GPI-anchored proteins, and they were recently reported to regulate cell polar expansion and cell wall synthesis redundantly in roots. Here, we report that, they are also redundantly crucial for seed production and seed morphogenesis in Arabidopsis through regulating maternal Integument development. Their loss-of-functions resulted in disrupted development of Integuments that failed to protect embryo sacs from exposure to external space due to physical restriction, and lead to female gametophytic abortion. Interestingly, those less defective ovules could be fertilized and develop into seeds normally, however, their seed morphogenesis was largely affected. Our research made SKS1, SKS2, SKS3 and SKU5 be not only the first class of GPI-anchored proteins that could regulate maternal Integument development, but also the first class of proteins that could regulate cell polar expansion in both root and Integument cells besides several MAPK cascade components. Our study also underlined the regulation by Integument development in reproductive processes.
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gpi anchored sku5 sks are maternally required for Integument development in arabidopsis
bioRxiv, 2019Co-Authors: Elisa Fiume, Ke Zhou, Delphine Devos, Enrico MagnaniAbstract:ABSTRACT Glycosylphosphatidylinositol-anchored proteins (GPI-APs) play crucial roles in various processes in eukaryotes. In Arabidopsis, SKS1, SKS2, SKS3 and SKU5 from SKU5/SKS gene family could encode GPI-anchored proteins, and they were recently reported to regulate cell polar expansion and cell wall synthesis redundantly in roots. Here, we report that, they are also redundantly crucial for seed production and seed morphogenesis in Arabidopsis through regulating maternal Integument development. Their loss-of-functions resulted in disrupted development of Integuments that failed to protect embryo sacs from exposure to external space due to physical restriction, and lead to female gametophytic abortion. Interestingly, those less defective ovules could be fertilized and develop into seeds normally, however, their seed morphogenesis was largely affected. Our research made SKS1, SKS2, SKS3 and SKU5 be not only the first class of GPI-anchored proteins that could regulate maternal Integument development, but also the first class of proteins that could regulate cell polar expansion in both root and Integument cells besides several MAPK cascade components. Our study also underlined the regulation by Integument development in reproductive processes.
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Developmental patterning of sub-epidermal cells in the outer Integument of Arabidopsis seeds.
PloS one, 2017Co-Authors: Elisa Fiume, Olivier Coen, Loic Lepiniec, Enrico MagnaniAbstract:The seed, the reproductive unit of angiosperms, is generally protected by the seed coat. The seed coat is made of one or two Integuments, each comprising two epidermal cells layers and, in some cases, extra sub-epidermal cell layers. The thickness of the seed-coat affects several aspects of seed biology such as dormancy, germination and mortality. In Arabidopsis, the inner Integument displays one or two sub-epidermal cell layers that originate from periclinal cell divisions of the innermost epidermal cell layer. By contrast, the outer Integument was considered to be two-cell layered. Here, we show that sub-epidermal chalazal cells grow in between the epidermal outer Integument cell layers to create an incomplete three-cell layered outer Integument. We found that the MADS box transcription factor TRANSPARENT TESTA 16 represses growth of the chalaza and formation of sub-epidermal outer Integument cells. Finally, we demonstrate that sub-epidermal cells of the outer and inner Integument respond differently to the repressive mechanism mediated by FERTILIZATION INDEPENDENT SEED Polycomb group proteins and to fertilization signals. Our data suggest that Integument cell origin rather than sub-epidermal cell position underlies different responses to fertilization.
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Developmental patterning of the sub-epidermal Integument cell layer in Arabidopsis seeds.
Development (Cambridge England), 2017Co-Authors: Olivier Coen, Elisa Fiume, Loic Lepiniec, Delphine De Vos, Christine Péchoux, Enrico MagnaniAbstract:Angiosperm seed development is a paradigm of tissue cross-talk. Proper seed formation requires spatial and temporal coordination of the fertilization products - embryo and endosperm - and the surrounding seed coat maternal tissue. In early Arabidopsis seed development, all seed Integuments were thought to respond homogenously to endosperm growth. Here, we show that the sub-epidermal Integument cell layer has a unique developmental program. We characterized the cell patterning of the sub-epidermal Integument cell layer, which initiates a previously uncharacterized extra cell layer, and identified TRANSPARENT TESTA 16 and SEEDSTICK MADS box transcription factors as master regulators of its polar development and cell architecture. Our data indicate that the differentiation of the sub-epidermal Integument cell layer is insensitive to endosperm growth alone and to the repressive mechanism established by FERTILIZATION INDEPENDENT ENDOSPERM and MULTICOPY SUPPRESSOR OF IRA1 Polycomb group proteins. This work demonstrates the different responses of epidermal and sub-epidermal Integument cell layers to fertilization.
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Growth of the Arabidopsis sub-epidermal Integument cell layers might require an endosperm signal
Plant Signaling and Behavior, 2017Co-Authors: Elisa Fiume, Olivier Coen, Loic Lepiniec, Enrico MagnaniAbstract:The seed, the reproductive unit of angiosperms, is physically protected by the seed coat. The seed coat develops from the ovule Integuments after fertilization. The Arabidopsis ovule Integuments are made of 5-6 cell layers of epidermal and sub-epidermal origin. The growth of the epidermal Integument cell layers responds to an endosperm signal mediated by the AGAMOUS-LIKE 62 MADS box transcription factor with limited embryo contribution. By contrast, the sub-epidermal Integument cell layers require the embryo to expand whereas the role of the endosperm is still unclear. Here, we analyzed the development of the subepidermal Integument cell layers in agl62 mutant seeds, which undergo premature endosperm cellularization and arrest. Our data suggest that embryo and endosperm are both necessary to trigger the expansion of the sub-epidermal Integument cell layers.
Lycia De Brito-gitirana - One of the best experts on this subject based on the ideXlab platform.
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Comparative analysis of the Integument of different tree frog species from Ololygon and Scinax genera (Anura: Hylidae)
Zoologia, 2017Co-Authors: Henrique Alencar Meira Da Silva, Thiago Silva-soares, Lycia De Brito-gitiranaAbstract:ABSTRACT The Integuments of ten treefrog species of two genera from Scinaxnae - O. angrensis (Lutz, 1973), O. flavoguttata (Lutz & Lutz, 1939), O. humilis (Lutz & Lutz, 1954), O. perpusilla (Lutz & Lutz, 1939), O. v-signata (Lutz, 1968), Scinax hayii (Barbour, 1909), S. similis (Cochran, 1952), O. trapicheroi (Lutz & Lutz, 1954) and S. x-signatus (Spix, 1824) - were investigated using conventional and histochemical techniques of light microscopy, and polarized light microscopy. All Integuments showed the basic structure of the anuran Integument. Moreover, the secretory portions of exocrine glands, such as serous merocrine and apocrine glands, were found to be restricted to the spongious dermis. Lipid content occurred together with the heterogeneous secretory material of the glands with an apocrine secretion mechanism. In addition, clusters of these apocrine glands were present in the ventrolateral Integument of some species. Melanophores were also visualized in all examined hylids. However, the occurrence of iridophores, detected through polarized light microscopy, varied according to the species. The Eberth-Katschenko layer occurred in the dorsal Integument from both genera, but it was only present in the ventral Integument of O. albicans, O. angrensis, O. flavoguttata, O. perpusilla and O. v-signata. Although the Integument of all treefrogs showed the same basic structure, some characteristics were genus-specific; however, these features alone may not be used to distinguish both genera
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Glycosaminoglycans and glycoconjugates in the adult anuran Integument (Lithobates catesbeianus)
Micron, 2010Co-Authors: Adriana Alves Pelli, Leonardo Paes Cinelli, Paulo A.s. Mourão, Lycia De Brito-gitiranaAbstract:Glycosaminoglycans (GAGs) from the Integument of Lithobates catesbeianus were biochemically characterized and histochemically localized. Moreover, carbohydrate distribution was investigated using conventional and lectin histochemistry at light microscopy. Hyaluronan (HA), dermatan sulfate (DS) and a heparanoid were found in the Integument. Sulfated and carboxylated GAGs were visualized in the Eberth-Katschenko (EK) layer, in the mucous glands, in the hypodermis as well as in the mast cells. Furthermore, glucose and galactose were identified in the Integument through thin layer chromatography (TLC) assays. N-Acetyl-β-glucosamine residues were identified in the mucous glandular cells, between the corneum and spinosum strata, in the subepidermal region, and in the EK layer. N-Acetyl-galactosamine residues were evident in the EK layer, corresponding to a residue of the dermatan sulfate chain, which may be related to the collagenous fiber arrangement. These glycoconjugates occurred as secretory glandular products and as dermal structural elements. Moreover, HA and DS are the predominant GAGs in the L. catesbeianus Integument. Considering the importance of glycoconjugates, they play a significant role to the integrity of the skin, providing mechanical support for Integument cells. In addition, they are important to the water regulation mechanisms, since L. catesbeianus is preferably aquatic.
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Microscopical methods promote the understanding of the Integument biology of Rhinella ornata.
Micron (Oxford England : 1993), 2008Co-Authors: Flavia Abreu Felsemburgh, Sergio Potsch De Carvalho-e-silva, Pablo Germano De Almeida, Lycia De Brito-gitiranaAbstract:Abstract In Rhinella ornata , the Integument of different body regions was investigated using low-vacuum scanning electron and light microscopy through histochemical and immunohistochemical methods, and revealed the basic structure found in other anurans. Keratinocytes formed the keratinized squamous stratified epithelium, and flask cells occurred among the epidermal superficial layer. Just below the epidermis, the dermis was subdivided into a spongious dermis and a compact dermis. Mixed and granular glands were located in the spongious dermis, and myoepithelial cells surrounded their secretory portions. The Eberth–Katschenko (EK) layer occurred as basophilic areas between the spongious and compact dermis and throughout the spongious dermis. A series of alternating layers of bundles of collagenous fibers characterized the compact dermis, being firmly attached to a thin hypodermis. Regarding the morphological features, each Integument region revealed distinct structural aspects. The dorsal Integument was rougher than ventral, having conical tubercles and spines upon the verrucae. In the ventral and subgular regions, the slightly elevations are visualized, tubercles were absent but some spines occurred. The pelvic Integument had a non-keratinized epidermis with an irregular profile and small poorly developed elevations. In addition, the EK layer was absent, and the presence of numerous blood vessels suggests its participation in water absorption and distribution. In the parotoid gland, the epidermis was similar to the dorsal Integument; except that the reticular dermis was present, and contained three exocrine glandular types. Expression of cytokeratin was evident in the basal and intermediary layer, but absent in the cornified layer. Flask cells showed strong cytokeratin labeling. Consequently, the Integument had the basic morphology, but exhibits regional characteristics, which may be related to the physiology of each surface.
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Dermatan sulfate is the major metachromatic glycosaminoglycan in the Integument of the anuran Bufo ictericus.
Comparative biochemistry and physiology. Part B Biochemistry & molecular biology, 2006Co-Authors: Adriana Alves Pelli, Paulo A.s. Mourão, Rodrigo Alves Azevedo, Leonardo P. Cinelli, Lycia De Brito-gitiranaAbstract:Glycosaminoglycans from the ventral and dorsal Integuments of the anuran Bufo ictericus were characterized based on biochemical and histochemical methods. Dermatan sulfate is the major metachromatic glycosaminoglycan found in these tissues, but small amount of heparan sulfate was also detected. The average molecular mass of the dermatan sulfate is approximately 20 kDa, similar to the glycosaminoglycan isolated from mammalian skin. In addition, the amphibian Integument contains high amounts of hyaluronic acid, especially in the ventral area. We also observed that the glycosaminoglycans occur in the anuran Integument as irregular deposits through the spongious dermis and in the mast cells, as revealed by histochemical analysis using Alcian blue, dimethylmethylene blue and toluidine blue stains. The concentration and composition of glycosaminoglycans found in the amphibian Integument resemble those from mammalian skin except for the higher concentration of hyaluronic acid in the amphibian tissue. Possibly, this observation indicates that the function of the sulfated glycosaminoglycan in these tissues has been preserved during evolution, although the amphibian Integument and the human skin have their own particular physiology.
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Dermal collagen organization in Bufo ictericus and in Rana catesbeiana Integument (Anuran, Amphibian) under the evaluation of laser confocal microscopy.
Micron (Oxford England : 1993), 2005Co-Authors: Rodrigo Alves Azevedo, Andréa Souza De Jesus Santana, Lycia De Brito-gitiranaAbstract:Collagen structural organization plays an important role in the mechanical property of the vertebrate Integument. Bufo ictericus and Rana catesbeiana Integument was investigated by light microscopy and laser confocal microscopy. Collagenous elements of the dermis were statistical analyzed. The Integument is formed by the keratinized squamous stratified epidermis supported by the dermis that is subdivided into the spongious layer with a loose arrangement, and the compact layer formed by collagenous fibers arranged compactly in a criss-crossed manner. Thick collagenous columns have a perpendicular trajectory, and are formed by the assembling of alternating collagenous lamellae in both animals. Short intercolumns of collagenous fibrils connecting collagenous lamellae obliquely or transversally are observed in R. catesbeiana dorsal Integument. The present study provides evidences that B. ictericus and R. catesbeiana Integument has well-organized compact dermis, constituted by collagenous lamellae in a plywood manner. The Integument organization is in contrast to the literature in some aspects. This dermal arrangement is important to the biomechanical property of both anuran Integuments.
Elisa Fiume - One of the best experts on this subject based on the ideXlab platform.
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GPI-anchored SKU5/SKS are maternally required for Integument development in Arabidopsis
2019Co-Authors: Ke Zhou, Elisa Fiume, Delphine De Vos, Enrico MagnaniAbstract:ABSTRACT Glycosylphosphatidylinositol-anchored proteins (GPI-APs) play crucial roles in various processes in eukaryotes. In Arabidopsis, SKS1, SKS2, SKS3 and SKU5 from SKU5/SKS gene family could encode GPI-anchored proteins, and they were recently reported to regulate cell polar expansion and cell wall synthesis redundantly in roots. Here, we report that, they are also redundantly crucial for seed production and seed morphogenesis in Arabidopsis through regulating maternal Integument development. Their loss-of-functions resulted in disrupted development of Integuments that failed to protect embryo sacs from exposure to external space due to physical restriction, and lead to female gametophytic abortion. Interestingly, those less defective ovules could be fertilized and develop into seeds normally, however, their seed morphogenesis was largely affected. Our research made SKS1, SKS2, SKS3 and SKU5 be not only the first class of GPI-anchored proteins that could regulate maternal Integument development, but also the first class of proteins that could regulate cell polar expansion in both root and Integument cells besides several MAPK cascade components. Our study also underlined the regulation by Integument development in reproductive processes.
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gpi anchored sku5 sks are maternally required for Integument development in arabidopsis
bioRxiv, 2019Co-Authors: Elisa Fiume, Ke Zhou, Delphine Devos, Enrico MagnaniAbstract:ABSTRACT Glycosylphosphatidylinositol-anchored proteins (GPI-APs) play crucial roles in various processes in eukaryotes. In Arabidopsis, SKS1, SKS2, SKS3 and SKU5 from SKU5/SKS gene family could encode GPI-anchored proteins, and they were recently reported to regulate cell polar expansion and cell wall synthesis redundantly in roots. Here, we report that, they are also redundantly crucial for seed production and seed morphogenesis in Arabidopsis through regulating maternal Integument development. Their loss-of-functions resulted in disrupted development of Integuments that failed to protect embryo sacs from exposure to external space due to physical restriction, and lead to female gametophytic abortion. Interestingly, those less defective ovules could be fertilized and develop into seeds normally, however, their seed morphogenesis was largely affected. Our research made SKS1, SKS2, SKS3 and SKU5 be not only the first class of GPI-anchored proteins that could regulate maternal Integument development, but also the first class of proteins that could regulate cell polar expansion in both root and Integument cells besides several MAPK cascade components. Our study also underlined the regulation by Integument development in reproductive processes.
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Developmental patterning of sub-epidermal cells in the outer Integument of Arabidopsis seeds.
PloS one, 2017Co-Authors: Elisa Fiume, Olivier Coen, Loic Lepiniec, Enrico MagnaniAbstract:The seed, the reproductive unit of angiosperms, is generally protected by the seed coat. The seed coat is made of one or two Integuments, each comprising two epidermal cells layers and, in some cases, extra sub-epidermal cell layers. The thickness of the seed-coat affects several aspects of seed biology such as dormancy, germination and mortality. In Arabidopsis, the inner Integument displays one or two sub-epidermal cell layers that originate from periclinal cell divisions of the innermost epidermal cell layer. By contrast, the outer Integument was considered to be two-cell layered. Here, we show that sub-epidermal chalazal cells grow in between the epidermal outer Integument cell layers to create an incomplete three-cell layered outer Integument. We found that the MADS box transcription factor TRANSPARENT TESTA 16 represses growth of the chalaza and formation of sub-epidermal outer Integument cells. Finally, we demonstrate that sub-epidermal cells of the outer and inner Integument respond differently to the repressive mechanism mediated by FERTILIZATION INDEPENDENT SEED Polycomb group proteins and to fertilization signals. Our data suggest that Integument cell origin rather than sub-epidermal cell position underlies different responses to fertilization.
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Developmental patterning of the sub-epidermal Integument cell layer in Arabidopsis seeds.
Development (Cambridge England), 2017Co-Authors: Olivier Coen, Elisa Fiume, Loic Lepiniec, Delphine De Vos, Christine Péchoux, Enrico MagnaniAbstract:Angiosperm seed development is a paradigm of tissue cross-talk. Proper seed formation requires spatial and temporal coordination of the fertilization products - embryo and endosperm - and the surrounding seed coat maternal tissue. In early Arabidopsis seed development, all seed Integuments were thought to respond homogenously to endosperm growth. Here, we show that the sub-epidermal Integument cell layer has a unique developmental program. We characterized the cell patterning of the sub-epidermal Integument cell layer, which initiates a previously uncharacterized extra cell layer, and identified TRANSPARENT TESTA 16 and SEEDSTICK MADS box transcription factors as master regulators of its polar development and cell architecture. Our data indicate that the differentiation of the sub-epidermal Integument cell layer is insensitive to endosperm growth alone and to the repressive mechanism established by FERTILIZATION INDEPENDENT ENDOSPERM and MULTICOPY SUPPRESSOR OF IRA1 Polycomb group proteins. This work demonstrates the different responses of epidermal and sub-epidermal Integument cell layers to fertilization.
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Growth of the Arabidopsis sub-epidermal Integument cell layers might require an endosperm signal
Plant Signaling and Behavior, 2017Co-Authors: Elisa Fiume, Olivier Coen, Loic Lepiniec, Enrico MagnaniAbstract:The seed, the reproductive unit of angiosperms, is physically protected by the seed coat. The seed coat develops from the ovule Integuments after fertilization. The Arabidopsis ovule Integuments are made of 5-6 cell layers of epidermal and sub-epidermal origin. The growth of the epidermal Integument cell layers responds to an endosperm signal mediated by the AGAMOUS-LIKE 62 MADS box transcription factor with limited embryo contribution. By contrast, the sub-epidermal Integument cell layers require the embryo to expand whereas the role of the endosperm is still unclear. Here, we analyzed the development of the subepidermal Integument cell layers in agl62 mutant seeds, which undergo premature endosperm cellularization and arrest. Our data suggest that embryo and endosperm are both necessary to trigger the expansion of the sub-epidermal Integument cell layers.
Ryan H Brown - One of the best experts on this subject based on the ideXlab platform.
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Expression of ovule and Integument‐associated genes in reduced ovules of Santalales
Evolution & Development, 2010Co-Authors: Ryan H Brown, Daniel L. Nickrent, Charles S. GasserAbstract:1Present address: National Small Grains Germplasm Research Facility, USDA-ARS, Aberdeen, ID 83210, USA SUMMARY Santalales comprise mainly parasitic plants including mistletoes and sandalwoods. Bitegmic ovules similar to those found in most other angiosperms are seen in many members of the order, but other members exhibit evolutionary reductions to the unitegmic and ategmic conditions. In some mistletoes, extreme reduction has resulted in the absence of emergent ovules such that embryo sacs appear to remain embedded in placental tissues. Three santalalean representatives (Comandra, Santalum, and Phoradendron), displaying unitegmic, and ategmic ovules, were studied. Observed ovule morphologies were consistent with published reports, including Phoradendron serotinum, which we interpret as having reduced ategmic ovules, consistent with earlier reports on this species. For further understanding of the nature of the ovule reductions we isolated orthologs of the Arabidopsis genes AIntegumentA (ANT) and BELL1 (BEL1), which are associated with ovule development in this species. We observed ovular expression of ANT and BEL1 in patterns largely resembling those seen in the Integumented ovules of Arabidopsis. These genes were found to be expressed in the Integument of unitegmic ovules and in the surface layers of ategmic ovules, and in some cases, expression of BEL1 was also observed in the surrounding carpel tissue. We hypothesize that ategmic ovules derive from a fusion of the Integuments with the nucellus or that the nucellus has taken on some of the characteristics confined to Integuments in ancestral species.
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Expression of ovule and Integument‐associated genes in reduced ovules of Santalales
Evolution & development, 2010Co-Authors: Ryan H Brown, Daniel L. Nickrent, Charles S. GasserAbstract:Santalales comprise mainly parasitic plants including mistletoes and sandalwoods. Bitegmic ovules similar to those found in most other angiosperms are seen in many members of the order, but other members exhibit evolutionary reductions to the unitegmic and ategmic conditions. In some mistletoes, extreme reduction has resulted in the absence of emergent ovules such that embryo sacs appear to remain embedded in placental tissues. Three santalalean representatives (Comandra, Santalum, and Phoradendron), displaying unitegmic, and ategmic ovules, were studied. Observed ovule morphologies were consistent with published reports, including Phoradendron serotinum, which we interpret as having reduced ategmic ovules, consistent with earlier reports on this species. For further understanding of the nature of the ovule reductions we isolated orthologs of the Arabidopsis genes AIntegumentA (ANT) and BELL1 (BEL1), which are associated with ovule development in this species. We observed ovular expression of ANT and BEL1 in patterns largely resembling those seen in the Integumented ovules of Arabidopsis. These genes were found to be expressed in the Integument of unitegmic ovules and in the surface layers of ategmic ovules, and in some cases, expression of BEL1 was also observed in the surrounding carpel tissue. We hypothesize that ategmic ovules derive from a fusion of the Integuments with the nucellus or that the nucellus has taken on some of the characteristics confined to Integuments in ancestral species.
