Embryogenesis in plants

Wardlaw, C. W.

doi:10.5962/bhl.title.5655

Cited by 136 publications

(66 citation statements)

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“…Severa1 conclusions have emerged from these studies: (1) early embryogenesis is often characterized by predictable patterns of cell division, although the real significance of these patterns to plant development remains to be resolved; (2) the zygote is typically a polarized cell that divides to form two cells with different features and developmental fates; (3) the suspensor is usually produced from the basal cell adjacent to the micropylar end of the ovule; and (4) development of the suspensor generally precedes differentiation of the embryo proper. Primitive vascular plants also contain structures that resemble a suspensor (Wardlaw, 1955). The suspensor is therefore a common feature of plant embryogenesis.…”

Section: Introduction Suspensor Morphologymentioning

confidence: 99%

Embryogenesis in Angiosperms: Development of the Suspensor.

1993

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Section: Introduction Suspensor Morphologymentioning

confidence: 99%

Embryogenesis in Angiosperms: Development of the Suspensor.

1993

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“…Whether maternal factors as in the fruit fly Drosophila (Ingham, 1988;St Johnston and Nusslein-Volhard, 1992) or posffertilization embryonic factors specify patterns in the plant embryo is not known. Wardlaw (1955) suggested that the shift from radial to bilateral symmetry could be explained by bilateral gradients in the embryo sac. Other evidence suggests that maternal factors, if they do influence the polarity of the zygotic embryo, may not be absolutely required (for review see Goldberg et al, 1994;West and Harada, 1993).…”

Section: Introductionmentioning

confidence: 99%

Influence of auxin on the establishment of bilateral symmetry in monocots

Fischer

Neuhaus²

1996

The Plant Journal

104

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SummaryTo study the influence of auxin on the shift from radial to bilateral symmetry during monocot embryogenesis, the fate of young wheat (Triticurn aestivum L.) zygotic embryos has been manipulated in vitro by adding auxins, an auxin transport inhibitor and an auxin antagonist to the culture medium. The two synthetic auxins used, 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), induced identical phenotypes. In the most severe cases, the shift from radial to bilateral symmetry was blocked resulting in continuous uniform radial growth. The natural auxin indole-3-acetic acid (IAA) induced the same phenotype. The effect of 2,4,5-T and 2,4-D depended on their concentrations and on the developmental stage of the isolated embryos. In the presence of 2,3,5-triiodobenzoic acid (TIBA), an auxin transport inhibitor, the overall embryo symmetry was abnormal. The relative position of the shoot apical meristem in comparison with the scutellum was anomalous. The quality of shoot apical meristem and the scutellum differentiation was altered compared with normal developed embryos. No root meristem was differentiated. The effect of TIBA depends on its concentration and on the developmental stage of the isolated embryos. By contrast, 2-(pchlorophenoxy)-2-methylpropionic acid (PCIB) which is described as an auxin antagonist, has no visible direct effect on the embryonic symmetry. These observations indicate that auxin influences the change from radial symmetry to embryonic polarity during monocot embryogenesis. A model of auxin action during early wheat embryo development is proposed.

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“…Figures 1H and 2E, the hypophysis, the uppermost derivative of the basal cell, serves as the precursor to the root cortex initials and the central region of the root cap (Schulz and Jensen, 1968a;Tykarska, 1979;. The suspensor is an ephemeral embryonic structure that, as shown in Figure 2E, comprises a single file of 6 to 11 cells in Arabidopsis and oilseed rape, although there are substantial variations in the number and layers of suspensor cells in different plants (Maheshwari, 1950;Wardlaw, 1955;Tykarska, 1976;Marsden and Meinke, 1985;). This structure is thought to function in embryogenesis by pushing the embryo into the nutrient-rich endosperm and, possibly, by serving as a conduit for nutrients and growth factors from the maternal tissue to the embryo (Yeung and Meinke, 1993, this issue).…”

Section: Morphological Description Of Embryogenesismentioning

confidence: 99%

“…Studies using light and electron microscopy have provided detailed descriptions of the morphological and anatomical changes that characterize embryonic development (Maheshwari, 1950;Wardlaw, 1955;Natesh and Rau, 1984;Raghavan, 1986). Cellular differentiation has been studied largely in relationship to the biosynthesis and accumulation of storage proteins, lipids, and starch, macromolecular reserves that ultimately serve as nutrients for postgerminative seedlings (Jenner, 1982;Slack and Browse, 1984;Casey et al, 1986;Shotwell and Larkins, 1989).…”

Section: Introductionmentioning

confidence: 99%