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  • Articles  (34)
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  • 1
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Plant Physiology and Plant Molecular Biology 52 (2001), S. 233-267 
    ISSN: 1040-2519
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology
    Notes: Abstract The endosperm develops from the central cell of the megagametophyte after introduction of the second male gamete into the diploid central cell. Of the three forms of endosperm in angiosperms, the nuclear type is prevalent in economically important species, including the cereals. Landmarks in nuclear endosperm development are the coenocytic, cellularization, differentiation, and maturation stages. The differentiated endosperm contains four major cell types: starchy endosperm, aleurone, transfer cells, and the cells of the embryo surrounding region. Recent research has demonstrated that the first two phases of endosperm occur via mechanisms that are conserved among all groups of angiosperms, involving directed nuclear migration during the coenocytic stage and anticlinal cell wall deposition by cytoplasmic phragmoplasts formed in interzones between radial microtubular systems emanating from nuclear membranes. Complete cellularization of the endosperm coenocyte is achieved through centripetal growth of cell files, extending to the center of the endosperm cavity. Key points in cell cycle control and control of the MT (microtubular) cytoskeletal apparatus central to endosperm development are discussed. Specification of cell fates in the cereal endosperm appears to occur via positional signaling; cells in peripheral positions, except over the main vascular tissues, assume aleurone cell fate. Cells over the main vascular tissue become transfer cells and all interior cells become starchy endosperm cells. Studies in maize have implicated Crinkly4, a protein receptor kinase-like molecule, in aleurone cell fate specification.
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 83 (1991), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: We have analysed the effects of the lys 3a mutation on mRNA levels in the developing aleurone and starchy endosperm. The objective was to investigate whether the increase in non-hordein gene mRNA is a compensation for decreased hordein mRNA levels or if the increase is a result of a selective transcriptional or posttranscriptional regulation of specific genes. Our results show that protein Z and β-amylase which are downregulated by the lys 3a mutation are affected only in the starchy endosperm. In contrast, mRNA levels for the chymotrypsin inhibitors (CI-1, CI-2) are enhanced in the aleurone as well as in the starchy endosperm. The two isoform inhibitor genes of CI-1 (CI-1A, CI-1B) are differentially affected in the aleurone by the lys 3a mutation. The lys 3a gene enhances mRNA levels of two aleurone-specific genes. Together, these findings suggest that the lys 3a gene encodes or affects a regulatory factor which specifically modulates mRNA levels of several genes in different seed tissues.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of plant research 109 (1996), S. 301-313 
    ISSN: 1618-0860
    Keywords: Cereal ; Endosperm ; Microtubules ; Mitosis ; Morphogenesis ; Phragmoplast ; Rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The syncytial endosperm of rice undergoes cellularization according to a regular morphogenetic plan. At 3 days after pollination (dap) mitosis in the peripheral synctium ceases. Radial systems of microtubules emanating from interphase nuclei define nuclear-cytoplasmic domains (NCDs) which develop axes perpendicular, to the embryo sac wall. Free-growing anticlinal walls between adjacent NCDs compart-mentalize the cytoplasm into open-ended alveoli which are overtopped by syncytial cytoplasm adjacent to the central vacuole. At 4 dap, mitosis resumes as a wave originating adjacent to the vascular bundle. The spindles are oriented parallel to the alveolar walls and cell plates formed in association with interzonal phragmoplasts result in periclinal walls that cut off a peripheral layer of cells and an inner layer of alveoli displaced toward the center. Polarized growth of the newly formed alveoli and elongation of the anticlinal walls occurs during interphase. The next wave of cell division in the alveoli proceeds as the first and a second cylinder of cells is cut off inside the peripheral layer. The periods of polarized growth/anticlinal wall elongation alternating with periclinal cell division are repeated 3–4 times until the grain is filled by 5 dap.
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  • 4
    ISSN: 1432-2048
    Keywords: Abscisic acid and mRNA accumulation ; Aleurone ; Embryo development ; Hordeum (mRNA in aleurone) ; mRNA (cell specific accumulation)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The mechanisms underlying the response of the mature barley (Hordeum vulgare L.) aleurone layer to gibberellic acid have received much attention, but little is known about the developmental basis for this response. We have investigated the spatial and temporal accumulation of mRNAs complementary to two barleygrain cDNAs that are differentially expressed in the aleurone layer of the developing endosperm. Messenger RNA complementary to one of these clones (B11E; Jakobsen etal., 1989, Plant Mol. Biol. 12, 285–293) accumulates exclusively in the aleurone layer of developing grains where it is uniformly distributed in all three cell layers. Accumulation of B11E mRNA is first detectable 10 d post an thesis (DPA), increases 200-fold up to 25 DPA, and then declines towards grain maturity. Messenger RNA complementary to the other clone, B22E, shows a more complex pattern of expression. In addition to the aleurone layer, this mRNA accumulates in the vascular tissue of the maternal pericarp and embryo axis, as well as in the parenchyma cells of the embryonic scutellum. In excised immature embryos abscisic acid strongly suppresses accumulation of B22E mRNA. The B22E transcript is absent from mature embryos, but rapidly reappears after germination.
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  • 5
    ISSN: 1432-2048
    Keywords: Key words: Cell wall (endosperm) ; Development (cereal grain) ; Endosperm (development ; structure) ; Glucan (immunolocation) ; Grain development ; Oryza (cell wall)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Immunogold labeling was used to study the distribution of (1 → 3)-β-glucans and (1 → 3, 1 → 4)-β-glucans in the rice grain during cellularization of the endosperm. At approximately 3–5 d after pollination the syncytial endosperm is converted into a cellular tissue by three developmentally distinct types of wall. The initial free-growing anticlinal walls, which compartmentalize the syncytium into open-ended alveoli, are formed in the absence of mitosis and phragmoplasts. This stage is followed by unidirectional (centripetal) growth of the anticlinal walls mediated by adventitious phragmoplasts that form between adjacent interphase nuclei. Finally, the periclinal walls that divide the alveoli are formed in association with centripetally expanding interzonal phragmoplasts following karyokinesis. The second and third types of wall are formed alternately until the endosperm is cellular throughout. All three types of wall that cellularize the endosperm contain (1 → 3)-β-glucans but not (1 → 3, 1 → 4)-β-glucans, whereas cell walls in the surrounding maternal tissues contain considerable amounts of (1 → 3, 1 → 4)-β-glucans with (1 → 3)-β-glucans present only around plasmodesmata. The callosic endosperm walls remain thin and cell plate-like throughout the cellularization process, appearing to exhibit a prolonged juvenile state.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Sexual plant reproduction 12 (1999), S. 32-42 
    ISSN: 1432-2145
    Keywords: Key words Arabidopsis thaliana ; Alveoli ; Development ; Endosperm ; Microtubules ; Seeds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The process of endosperm development in Arabidopsis was studied using immunohistochemistry of tubulin/microtubules coupled with light and confocal laser scanning microscopy. Arabidopsis undergoes the nuclear type of development in which the primary endosperm nucleus resulting from double fertilization divides repeatedly without cytokinesis resulting in a syncytium lining the central cell. Development occurs as waves originating in the micropylar chamber and moving through the central chamber toward the chalazal tip. Prior to cellularization, the syncytium is organized into nuclear cytoplasmic domains (NCDs) defined by nuclear-based radial systems of microtubules. The NCDs become polarized in axes perpendicular to the central cell wall, and anticlinal walls deposited among adjacent NCDs compartmentalize the syncytium into open-ended alveoli overtopped by a crown of syncytial cytoplasm. Continued centripetal growth of the anticlinal walls is guided by adventitious phragmoplasts that form at interfaces of microtubules emanating from adjacent interphase nuclei. Polarity of the elongating alveoli is reflected in a subsequent wave of periclinal divisions that cuts off a peripheral layer of cells and displaces the alveoli centripetally into the central vacuole. This pattern of development via alveolation appears to be highly conserved; it is characteristic of nuclear endosperm development in angiosperms and is similar to ancient patterns of gametophyte development in gymnosperms.
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  • 7
    ISSN: 1573-5028
    Keywords: ADP-glucose pyrophosphorylase ; barley ; endosperm ; PCR ; cDNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Several cDNAs encoding the small and large subunit of ADP-glucose pyrophosphorylase (AGP) were isolated from total RNA of the starchy endosperm, roots and leaves of barley by polymerase chain reaction (PCR). Sets of degenerate oligonucleotide primers, based on previously published conserved amino acid sequences of plant AGP, were used for synthesis and amplification of the cDNAs. For either the endosperm, roots and leaves, the restriction analysis of PCR products (ca. 550 nucleotides each) has revealed heterogeneity, suggesting presence of three transcripts for AGP in the endosperm and roots, and up to two AGP transcripts in the leaf tissue. Based on the derived amino acid sequences, two clones from the endosperm, beps and bepl, were identified as coding for the small and large subunit of AGP, respectively, while a leaf transcript (blpl) encoded the putative large subunit of AGP. There was about 50% identity between the endosperm clones, and both of them were about 60% identical to the leaf cDNA. Northern blot analysis has indicated that beps and bepl are expressed in both the endosperm and roots, while blpl is detectable only in leaves. Application of the PCR technique in studies on gene structure and gene expression of plant AGP is discussed.
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  • 8
    ISSN: 1573-5028
    Keywords: ADP-glucose pyrophosphorylase ; Arabidopsis thaliana ; starch biosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract PCR amplification of cDNA prepared from poly(A)+ RNA from aerial parts of Arabidopsis thaliana, using degenerate nucleotide primers based on conserved regions between the large and small subunits of ADP-glucose pyrophosphorylase (AGP), yielded four different cDNAs of ca. 550 nucleotides each. Based on derived amino acid sequences, the identities between the clones varied from 49 to 69%. Sequence comparison to previously published cDNAs for AGP from various species and tissues has revealed that three of the amplified cDNAs (ApL1, ApL2 and ApL3) correspond to the large subunit of AGP, and one cDNA (ApS) encodes the small subunit of AGP. Both ApL1 and ApS were subsequently found to be present in a cDNA library made from Arabidopsis leaves. All four PCR products are encoded by single genes, as found by genomic Southern analysis.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Plant molecular biology 18 (1992), S. 1195-1198 
    ISSN: 1573-5028
    Keywords: abscisic acid ; barley ; endosperm ; seed protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 10
    ISSN: 1573-5028
    Keywords: barley ; endosperm coenocyte ; differential screening ; modified aleurone cells ; nucellus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cereal endosperm develops from a coenocyte to a cellular storage organ through formation of nucleo-cytoplasmic domains and cell wall deposition in the interzones between these domains. During its early stages, the endosperm develops in close contact with nucellus, the sporophytic tissue which gives rise to the megagametophyte. Owing to the positioning of the two tissues deeply within the ovary, neither cell types have been easily accessible for molecular studies. In this paper we report for the first time the cloning of molecular markers for the barley endosperm coenocyte and the nucellus. The novel END1 and NUC1 cDNAs were isolated by differential screening of a cDNA library from 5 DAP (days after pollination) ovaries using a positive probe from hand-dissected embryo sacs with adhering nucellus and testa cell layers, and a negative probe from pericarp. In situ and northern blot hybridization data show that END1 transcripts are asymmetrically distributed in teh endosperm coenocyte limited to an area over the nucellar projection. In the cellular endosperm, END1 transcripts are present in modified aleurone cells and a few layers of ventral starchy endosperm cells. The second clone, NUC1, hybridizes to transcripts in the nucellus before fertilization and in autolyzing nucellus cells after fertilization. At later stages, after the disappearance of nucellus, NUC1 transcripts are present in the nucellar epidermis and in the lateral cells of the nucellar projection. This work provide tools for future elucidation of the genes specifying endosperm histogenesis.
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