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Growth inhibition, turgor maintenance, and changes in yield threshold after cessation of solute import in pea epicotylsThe dependence of stem elongation on solute import was investigated in etiolated pea seedlings (Pisum sativum L. var Alaska) by excising the cotyledons. Stem elongation was inhibited by 60% within 5 hours of excision. Dry weight accumulation into the growing region stopped and osmotic pressure of the cell sap declined by 0.14 megapascal over 5 hours. Attempts to assay phloem transport via ethylenediaminetetraacetate-enhanced exudation from cut stems revealed no effect of cotyledon excision, indicating that the technique measured artifactual leakage from cells. Despite the drop in cell osmotic pressure, turgor pressure (measured directly via a pressure probe) did not decline. Turgor maintenance is postulated to occur via uptake of solutes from the free space, thereby maintaining the osmotic pressure difference across the cell membrane. Cell wall properties were measured by the pressure-block stress relaxation technique. Results indicate that growth inhibition after cotyledon excision was mediated primarily via an increase in the wall yield threshold.
Document ID
20040112096
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Schmalstig, J. G.
(University Park 16802 United States)
Cosgrove, D. J.
Date Acquired
August 21, 2013
Publication Date
January 1, 1988
Publication Information
Publication: Plant physiology
Volume: 88
ISSN: 0032-0889
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: DE-FG01-84ER13179
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Number 40-30
NASA Discipline Plant Biology
Non-NASA Center
NASA Program Space Biology

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