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Geotropic Response of Wheat Coleoptiles in Absence of Amyloplast Starch

Young coleoptiles of wheat (Triticum durum var. Henry), depleted of amyloplast starch by incubation at 30°C with gibberellin plus kinetin, retained their geotropic responsiveness. Depleted coleoptiles curved upward more slowly than controls, but this was commensurate with their slower growth. The ra...

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Detalles Bibliográficos
Autores principales: Pickard, Barbara Gillespie, Thimann, Kenneth V.
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 1966
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2195530/
https://www.ncbi.nlm.nih.gov/pubmed/5961354
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author Pickard, Barbara Gillespie
Thimann, Kenneth V.
author_facet Pickard, Barbara Gillespie
Thimann, Kenneth V.
author_sort Pickard, Barbara Gillespie
collection PubMed
description Young coleoptiles of wheat (Triticum durum var. Henry), depleted of amyloplast starch by incubation at 30°C with gibberellin plus kinetin, retained their geotropic responsiveness. Depleted coleoptiles curved upward more slowly than controls, but this was commensurate with their slower growth. The ratio of curvature to growth was about 50° per mm of elongation in both cases. Newly excised coleoptiles, though containing much more starch than incubated controls, curved only about 25° per mm. The tissue treated in gibberellin plus kinetin appeared to contain no starch when examined (a) freshly squashed, (b) as fixed material sectioned thin and stained by the PAS procedure, and (c) as electron micrographs. Shrunken, starch-free amyloplasts could be identified in certain regions, but these did not show evidence of asymmetric distribution under the influence of gravity. The possibilities that other organelles function as statoliths are considered, and it is concluded not only that georeception is independent of starch grains, but further that it may not be due to statoliths at all in an ordinary sense.
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spelling pubmed-21955302008-04-23 Geotropic Response of Wheat Coleoptiles in Absence of Amyloplast Starch Pickard, Barbara Gillespie Thimann, Kenneth V. J Gen Physiol Article Young coleoptiles of wheat (Triticum durum var. Henry), depleted of amyloplast starch by incubation at 30°C with gibberellin plus kinetin, retained their geotropic responsiveness. Depleted coleoptiles curved upward more slowly than controls, but this was commensurate with their slower growth. The ratio of curvature to growth was about 50° per mm of elongation in both cases. Newly excised coleoptiles, though containing much more starch than incubated controls, curved only about 25° per mm. The tissue treated in gibberellin plus kinetin appeared to contain no starch when examined (a) freshly squashed, (b) as fixed material sectioned thin and stained by the PAS procedure, and (c) as electron micrographs. Shrunken, starch-free amyloplasts could be identified in certain regions, but these did not show evidence of asymmetric distribution under the influence of gravity. The possibilities that other organelles function as statoliths are considered, and it is concluded not only that georeception is independent of starch grains, but further that it may not be due to statoliths at all in an ordinary sense. The Rockefeller University Press 1966-05-01 /pmc/articles/PMC2195530/ /pubmed/5961354 Text en Copyright © 1966 by The Rockefeller University Press This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/).
spellingShingle Article
Pickard, Barbara Gillespie
Thimann, Kenneth V.
Geotropic Response of Wheat Coleoptiles in Absence of Amyloplast Starch
title Geotropic Response of Wheat Coleoptiles in Absence of Amyloplast Starch
title_full Geotropic Response of Wheat Coleoptiles in Absence of Amyloplast Starch
title_fullStr Geotropic Response of Wheat Coleoptiles in Absence of Amyloplast Starch
title_full_unstemmed Geotropic Response of Wheat Coleoptiles in Absence of Amyloplast Starch
title_short Geotropic Response of Wheat Coleoptiles in Absence of Amyloplast Starch
title_sort geotropic response of wheat coleoptiles in absence of amyloplast starch
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2195530/
https://www.ncbi.nlm.nih.gov/pubmed/5961354
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