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Cytochemical localization of calcium in cap cells of primary roots of Zea mays LThe distribution of calcium (Ca) in caps of vertically- and horizontally-oriented roots of Zea mays was monitored to determine its possible role in root graviresponsiveness. A modification of the antimonate precipitation procedure was used to localize Ca in situ. In vertically-oriented roots, the presumed graviperceptive (i.e., columella) cells were characterized by minimal and symmetric staining of the plasmalemma and mitochondria. No precipitate was present in plasmodesmata or cell walls. Within 5 min after horizontal reorientation, staining was associated with the portion of the cell wall adjacent to the distal end of the cell. This asymmetric staining persisted throughout the onset of gravicurvature. No staining of lateral cell walls of columella cells was observed at any stage of gravicurvature, suggesting that a lateral flow of Ca through the columella tissue of horizontally-oriented roots does not occur. The outermost peripheral cells of roots oriented horizontally and vertically secrete Ca through plasmodesmata-like structures in their cell walls. These results are discussed relative to proposed roles of root-cap Ca in root gravicurvature.
Document ID
Document Type
Reprint (Version printed in journal)
Moore, R. (Baylor University Waco, Texas 76798, United States)
Date Acquired
August 21, 2013
Publication Date
January 1, 1986
Publication Information
Publication: Journal of experimental botany
Volume: 37
Issue: 174
ISSN: 0022-0957
Subject Category
Life Sciences (General)
Distribution Limits
NASA Discipline Plant Biology
Non-NASA Center