An ultrastructural study of early endosperm development and synergid changes in unfertilized cotton ovules

Jensen, William A.; Schulz, Patricia; Ashton, Mary E.

doi:10.1007/bf00391917

Cited by 52 publications

(28 citation statements)

References 13 publications

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“…The tip of each of these walls grows in the absence of microtubules, similar to the growth seen in Stellaria (Newcomb and Fowke 1973) and Haemanthus (Newcomb 1978). But this is in contrast to reports of apical wall growth in the endosperm in the presence of microtubules in other soybean genotypes (Dute and Peterson 1992), wheat (Mares et al 1977), cotton (Jensen et al 1977), and Arabidopsis (Mansfield and Briarty 1990). We do not believe that our different results, when compared with other soybean genotypes, are a genotype-specific trait or that they resulted from poor tissue preparation, because microtubules were noted at other stages of endosperm development and in other tissues.…”

Section: Discussioncontrasting

confidence: 50%

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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Section: Discussioncontrasting

confidence: 50%

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

Chamberlin¹,

Horner²,

Palmer³

1994

International Journal of Plant Sciences

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“…Tilton (1981) has proposed that the PT may release hormones after germination that cause the synthesis of both autolytic and chemotropic compounds in at least one synergid resulting in the degeneration of that synergid. This has been confirmed in vitro by the experiments of Jensen et al (1977). In our experiments, in which the style was cut off prior to the arrival of the PT in the ovary, no synergid degeneration occurred, suggesting that the degeneration of the synergid is triggered only after the PTs penetrate the ovary.…”

Section: Synergid Degenerationsupporting

confidence: 61%

Synergid degeneration in Nicotiana: a quantitative, fluorochromatic and chlorotetracycline study

Huang

Russell

1992

Sexual Plant Reprod

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Synergid degeneration was examined in the isolated embryo sac and egg apparatus of Nicotiana tabacum using quantitative cytology, fluorochromatic reaction (FCR) and chlorotetracycline (CTC). Most synergid degeneration occurs after pollen tubes (PT) arrive in the ovarian chamber between 42 and 48 h after pollination; synergid degeneration was precluded when PT were prevented from entering the ovary by stylar excision indicating that the signal that triggers synergid degeneration travels only relatively short distances in this plant. There was no evidence for any preferentiality between right or left synergids with regard to cell size or degeneration pattern. FCR staining confirms that synergid degeneration involves the loss of membrane integrity and is a reliable indicator of the onset of degeneration. CTC labeling of the degenerated synergid reveals that a concentrated reserve of membrane-bound calcium is present in the receptive synergid, possibly aiding in the attraction, arrest and discharge of the PT, releasing the sperms into the receptive ES.

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“…F^rom evidence in Gossypium (Jensen, Schulz and Ashton, 1977), Proboscidea (Mogensen, 1978b) and Nicotiana (Mogensen and Suthar, 1979), it appears that pollen tube cytoplasm is in a degenerate state before a tube penetrates a synergid. Mogensen (1978b) suggested that the factor initiating this degeneration is of synergid origin whereas Haberlandt (1927) believed synergids secrete a substance which dissolves the end of pollen tubes.…”

Section: Discussion and Reviewmentioning

confidence: 99%

OVULE DEVELOPMENT IN ORNITHOGALUM CAUDATUM (LILIACEAE) WITH A REVIEW OF SELECTED PAPERS ON ANGIOSPERM REPRODUCTION

Tilton

1981

New Phytologist

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SUMMARYThe chalazal end of the egg projects beyond the synergids while the micropylar end is in contact with the nucellar epidermis. The egg nucleus and nucleolus are large and, along with most of the cytoplasm, are located chalazally while a large vacuole occupies the micropylar end. The egg cell wall is attenuated chalazally but, based on preliminary light microscope observations, it does appear to surround the entire cell in some cases. The synergids each have a large chalazal vacuole with the majority of their cytoplasm in the micropylar half of the cell. Nuclei and nucleoli are large and other organelles are numerous. Plastids and endoplasmic reticulum (ER) are more numerous chalazally while mitochondria appear to be evenly distributed. Filiform apparatus (FA) formation occurs late in synergid maturation. The FA is large, well developed, and is surrounded by a vacuolate zone. Various sized vesicles with fibrillar or flocculent contents occur within the FA. The FA stains for both protein and RNA in addition to carbohydrate which is the dominant component. The synergid walls have a knobbed ingrowth around the periphery of their micropylar end. Neither egg nor synergids store any metabolites.This information, coupled with overwhelming evidence from the literature reviewed, has led me to conclude all angiosperm synergids are active in synthesizing and, \ ia the FA, in secreting a substance(s) which influences the final phases of pollen tube growth. Movement of materials into a megagametophyte via the FA seems unlikely, but if it does occur, it is probably an inconsistent feature and only of trivial consequence.

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An ultrastructural study of early endosperm development and synergid changes in unfertilized cotton ovules

Cited by 52 publications

References 13 publications

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

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

Synergid degeneration in Nicotiana: a quantitative, fluorochromatic and chlorotetracycline study

OVULE DEVELOPMENT IN ORNITHOGALUM CAUDATUM (LILIACEAE) WITH A REVIEW OF SELECTED PAPERS ON ANGIOSPERM REPRODUCTION

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