NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Rapid, bilateral changes in growth rate and curvature during gravitropism of cucumber hypocotyls: implications for mechanism of growth controlThe growth response of etiolated cucumber (Cucumis sativus L.) hypocotyls to gravitropic stimulation was examined by means of time-lapse photography and high-resolution analysis of surface expansion and curvature. In comparison with video analysis, the technique described here has five- to 20-fold better resolution; moreover, the mathematical fitting method (cubic splines) allows direct estimation of local and integrated curvature. After switching seedlings from a vertical to horizontal position, both upper and lower surfaces of the stem reacted after a lag of about 11 min with a two- to three-fold increase in surface expansion rate on the lower side and a cessation of expansion, or slight compression, on the upper surface. This growth asymmetry was initiated simultaneously along the length of the hypocotyl, on both upper and lower surfaces, and did not migrate basipetally from the apex. Later stages in the gravitropic response involved a complex reversal of the growth asymmetry, with the net result being a basipetal migration of the curved region. This secondary growth reversal may reflect oscillatory and/or self-regulatory behaviour of growing cells. With some qualifications, the kinetics and pattern of growth response are consistent with a mechanism involving hormone redistribution, although they do not prove such a mechanism. The growth kinetics require a growth mechanism which can be stimulated by two- to three-fold or completely inhibited within a few minutes.
Document ID
20040090415
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Cosgrove, D. J.
(University Park 16802)
Date Acquired
August 21, 2013
Publication Date
January 1, 1990
Publication Information
Publication: Plant, cell & environment
Volume: 13
Issue: 3
ISSN: 0140-7791
Subject Category
Life Sciences (General)
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
NASA Discipline Number 29-20
NASA Program Space Biology
NASA Discipline Plant Biology

Available Downloads

There are no available downloads for this record.
No Preview Available