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Wall extensibility and gravitropic curvature of sunflower hypocotyls: correlation between timing of curvature and changes in extensibilityGravitropic curvature results from unequal growth rates on the upper and lower sides of horizontal stems. These unequal growth rates could be due to differences in wall extensibility between the two sides. To test this, the time course of curvature of horizontal sunflower (Helianthus annuus L.) hypocotyls was determined and compared with the time courses of changes in Instron-measured wall extensibility (PEx) of the upper and lower epidermal layers. As gravicurvature developed, so did the difference in PEx between the upper and lower epidermis. The enhanced growth rate on the lower side during the period of maximum increase in curvature was matched by PEx values greater than those of the vertical control, while the inhibited growth rate on the upper side was accompanied by PEx values below that of the control. The close correlation between changes in growth rates and alterations in PEx demonstrates that changes in wall extensibility play a major role in controlling gravicurvature.
Document ID
20040090416
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
Authors
Bagshaw, S. L.
(University of Washington Seattle, 98195)
Cleland, R. E.
Date Acquired
August 21, 2013
Publication Date
January 1, 1990
Publication Information
Publication: Plant, cell & environment
Volume: 13
ISSN: 0140-7791
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: NAGW-1394
CONTRACT_GRANT: DE-AM06-76ER73019
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
NASA Discipline Plant Biology
NASA Program Space Biology
NASA Discipline Number 29-20

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