The Fine Structure of the Developing Euphorbia dulcis Endosperm

Gori, P.

doi:10.1093/oxfordjournals.aob.a087479

Cited by 17 publications

(8 citation statements)

References 12 publications

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“…We speculate that the abundant rough ER in the endosperm may indicate synthesis of compounds for transport to the embryo. These suggestions agree with the earlier observations of other researchers on some species of angiosperms (Marinos, 1970;Newcomb, 1973b;Smart and O'Brien, 1983;Gori, 1987;Dute and Peterson, 1992). After the early heart stage of embryogenesis, a clear area appears adjacent to the embryo.…”

Section: Discussionsupporting

confidence: 93%

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Light and Electron Microscopic Examination of the Embryo and Endosperm Development in the Natural Tetraploid Trifolium Pratense L.

Algan

Bakar

1996

Israel J Plant Sci

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The ultrastructure of the embryo cells in ovules, from fertilization to the embryo maturity stage in the natural tetraploid Trifolium pratense L. that has a very low rate of seed formation, was examined. Following fertilization the vacuolar organization in the zygote changes. The zygote was a polarized cell and contained a central nucleus, mitochondria, plastids, ribosomes, and lipid bodies. Ribosomal concentration increases significantly after fertilization. The first division of the zygote was transverse or oblique and unequal. The primary endosperm nucleus divides before the zygote nucleus, forming a coenocytic nuclear endosperm; however, part of it later becomes cellular. At the earliest stage of embryo development, the cells were vacuolate, and plastids and mitochondria were simple in structure. During all stages of embryogenesis the suspensor cells were less electron dense than the adjoining embryo cells. Endosperm cellularization begins when the embryo has developed the globular embryo proper. Cellularization starts at the micropylar end of the embryo sac and progresses toward the chalaza! end. Dictyosome activity, ribosomal aggregation, and the amount of rough endoplasmic reticulum were highest during the late globular embryo stage. In addition, the vacuolar volume in the cells was reduced. Lipid bodies were present up to the early globular stage, then disappeared. The inner cell walls of the embryo were thin, with many plasmodesmata. These walls begin to thicken at the late globular stage. The results show a corresponding increase in the amount and activity of the metabolic machinery as the development of the embryo progresses.

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Section: Discussionsupporting

confidence: 93%

“…In many other species, zygote and developing embryo and endosperm formation have been described in great detail using electron microscopy (Schulz and Jensen, 1968b;Newcomb, 1973b;Newcomb and Fowke, 1973;Singh and Mogensen, 1975;Smart and O'Brien, 1983;Gori, 1987;Jones and Rost, 1989;Mansfield and Briarty, 1991).…”

Section: Introductionmentioning

confidence: 99%

Light and Electron Microscopic Examination of the Embryo and Endosperm Development in the Natural Tetraploid Trifolium Pratense L.

Algan

Bakar

1996

Israel J Plant Sci

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“…The presence of dense mucilage-like material in the wall space along the plasmalemma and the coincident thinning of the endosperm walls seem to justify the latter conclusion. The coincident accumulation of osmiophilic material in the wall space and the degeneration of the endosperm also have been observed in Zea (Schel et al 1984) and Euphorbia (Gori 1987).…”

Section: Discussionmentioning

confidence: 71%

Early Endosperm, Embryo, and Ovule Development in Glycine max (L.) Merr.

Chamberlin¹,

Horner²,

Palmer³

1994

International Journal of Plant Sciences

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Anatomical and ultrastructural aspects of soybean embryo, endosperm, and ovule development are described for the zygote to late heart-shaped embryo stages (0-35 d postfertilization). Nucellar cells subtending the degenerative synergid break down, allowing for pollen tube passage to this synergid. In 15 of 17 ovules studied, the degenerative synergid occupies a position abfunicular to the zygote. The inner integument differentiates into the endothelium and exterior layers of thick-walled cells at the globular embryo stage. The endothelium has a cuticle on its inner surface that begins to fragment at the onset of endosperm cellularization. Cellularization of the free-nuclear endosperm is initiated at the globular embryo stage by the formation of anticlinal ingrowths of the central cell wall. These walls fuse to form cylinders open to the central cell. Uninucleate cells are formed within the bases of the cylinders as periclinal walls are laid down. These latter walls are formed in the presence or absence of phragmoplasts. At the onset of cellularization, the endosperm forms a cellular sheath over the apex of the embryo, which partitions it from the central cell. The late globular embryo forms a cuticle on its surface but not on the suspensor. The endosperm cells of the chalazal process are suspended in a mucilage because of the loss of the central cell wall in this region. Endosperm degeneration occurs by two different processes: one involves wall thinning coincident with accumulation of mucilage exterior to the plasmalemma and within the cytoplasm; the other involves the fusion of vesicles to the plasmalemma and the concomitant release of cell-wall fibrils. The embryo becomes reoriented 900 to accommodate its expansion within the embryo sac. The integrated development and function of these tissues toward embryo and ovule maturation are discussed. Disciplines Agronomy and Crop Sciences | Botany | Plant Breeding and Genetics CommentsThis article is from International Journal of Plant Sciences 155 (1994): 421. RightsWorks produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted. Anatomical and ultrastructural aspects of soybean embryo, endosperm, and ovule development are described for the zygote to late heart-shaped embryo stages (0-35 d postfertilization). Nucellar cells subtending the degenerative synergid break down, allowing for pollen tube passage to this synergid. In 15 of 17 ovules studied, the degenerative synergid occupies a position abfunicular to the zygote. The inner integument differentiates into the endothelium and exterior layers of thick-walled cells at the globular embryo stage. The endothelium has a cuticle on its inner surface that begins to fragment at the onset of endosperm cellularization. Cellularization of the free-nuclear endosperm is initiated at the globular embryo stage by the formation of anticlinal ingrowths of the central cell wall. These walls fuse to form cylinders open to...

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“…Furthermore, some have speculated that the points of initiation of the free-growing anticlinal walls are related to transfer ingrowths (Dute and Peterson, 1992;Chamberlin et al, 1994). Besides operating in cereals, this mechanism of cell wall formation has also been reported for the endosperm of Arabidopsis (Mansfield and Briarty, 1990;Brown et al, 1999), Euphorbia dulcis (Gori, 1987), Glycine max (Dute and Peterson, 1992;Chamberlin et al, 1994), Haemanthus katherinae (Newcomb, 1978), Helianthus annus (Newcomb, 1973), Papaver nudicaule (Olson, 1981), Phaseolus vulgaris (Yeung and Cavey, 1988), and Stellaria media (Newcomb and Fowke, 1973).…”

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confidence: 87%

Syncytial-Type Cell Plates: A Novel Kind of Cell Plate Involved in Endosperm Cellularization of Arabidopsis

2000

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Cell wall formation in the syncytial endosperm of Arabidopsis was studied by using high-pressure-frozen/freeze-substituted developing seeds and immunocytochemical techniques. The endosperm cellularization process begins at the late globular embryo stage with the synchronous organization of small clusters of oppositely oriented microtubules ( ‫ف‬ 10 microtubules in each set) into phragmoplast-like structures termed mini-phragmoplasts between both sister and nonsister nuclei. These mini-phragmoplasts produce a novel kind of cell plate, the syncytial-type cell plate, from Golgiderived vesicles ‫ف‬ 63 nm in diameter, which fuse by way of hourglass-shaped intermediates into wide ( ‫ف‬ 45 nm in diameter) tubules. These wide tubules quickly become coated and surrounded by a ribosome-excluding matrix; as they grow, they branch and fuse with each other to form wide tubular networks. The mini-phragmoplasts formed between a given pair of nuclei produce aligned tubular networks that grow centrifugally until they merge into a coherent wide tubular network with the mini-phragmoplasts positioned along the network margins. The individual wide tubular networks expand laterally until they meet and eventually fuse with each other at the sites of the future cell corners. Transformation of the wide tubular networks into noncoated, thin ( ‫ف‬ 27 nm in diameter) tubular networks begins at multiple sites and coincides with the appearance of clathrin-coated budding structures. After fusion with the syncytial cell wall, the thin tubular networks are converted into fenestrated sheets and cell walls. Immunolabeling experiments show that the cell plates and cell walls of the endosperm differ from those of the embryo and maternal tissue in two features: their xyloglucans lack terminal fucose residues on the side chain, and callose persists in the cell walls after the cell plates fuse with the parental plasma membrane. The lack of terminal fucose residues on xyloglucans suggests that these cell wall matrix molecules serve both structural and storage functions. INTRODUCTIONIn higher plants, new cell walls are formed during cytokinesis by fusion of Golgi-derived vesicles into cell plates. The structure that gives rise to the cell plate is the phragmoplast, a complex arrangement of microtubules, microfilaments, Golgi-derived vesicles, and endoplasmic reticulum that assembles during late anaphase and is dismantled once the new wall is complete (Staehelin and Hepler, 1996;Smith, 1999). The phragmoplast cytoskeleton consists of two oppositely oriented sets of microtubules with their plus ends in the plane of the cell plate and two corresponding sets of actin microfilaments that do not overlap or directly abut. The first phragmoplast microtubules appear to arise from remnants of the mitotic spindle, but all later ones are polymerized anew, forming a cylinder that consolidates by shortening in length and widening in girth. During cell plate expansion, the microtubules depolymerize in the center and repolymerize along the edge, transforming the phragm...

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The Fine Structure of the Developing Euphorbia dulcis Endosperm

Cited by 17 publications

References 12 publications

Light and Electron Microscopic Examination of the Embryo and Endosperm Development in the Natural Tetraploid Trifolium Pratense L.

Light and Electron Microscopic Examination of the Embryo and Endosperm Development in the Natural Tetraploid Trifolium Pratense L.

Early Endosperm, Embryo, and Ovule Development in Glycine max (L.) Merr.

Syncytial-Type Cell Plates: A Novel Kind of Cell Plate Involved in Endosperm Cellularization of Arabidopsis

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