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The effect of a microgravity (space) environment on the expression of expansins from the peg and root tissues of Cucumis sativusIn young cucumber seedlings, the peg is a polar outgrowth of tissue that functions by snagging the seed coat, thereby freeing the cotyledons. The development of the peg is thought to be gravity-dependent and has become a model system for plant-gravity response. Peg development requires rapid cell expansion, a process thought to be catalyzed by alpha-expansins, and thus was a good system to identify expansins that were regulated by gravity. This study identified 7 new alpha-expansin cDNAs from cucumber seedlings (Cucumis sativus L. cv Burpee Hybrid II) and examined their expression patterns. Two alpha-expansins (CsExp3 and CsExp4) were more highly expressed in the peg and the root. Earlier reports stated that pegs tend not to form in the absence of gravity, so the expression levels were compared in the pegs of seedlings grown in space (STS-95), on a clinostat, and on earth (1 g). Pegs were observed to form at high frequency on clinostat and space-grown seedlings, yet on clinostats there was more than a 4-fold reduction in the expression of CsExp3 in the pegs of seedlings grown on clinostats vs. those grown at 1 g, while the CsExp4 gene appeared to be turned off (below detection limits). There were no detectable differences in expansin gene expression levels for the pegs of seedlings grown in space or in the orbiter environmental simulator (OES) (1 g) at NASA. The microgravity environment did not affect the expression of CsExp3 or CsExp4, and the clinostat did not simulate the microgravity environment well.
Document ID
20040088649
Acquisition Source
Kennedy Space Center
Document Type
Reprint (Version printed in journal)
Authors
Link, B. M.
(The University of Wisconsin Madison, WI 53706, United States)
Wagner, E. R.
Cosgrove, D. J.
Date Acquired
August 21, 2013
Publication Date
October 1, 2001
Publication Information
Publication: Physiologia plantarum
Volume: 113
Issue: 2
ISSN: 0031-9317
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: NAG10-0205
Distribution Limits
Public
Copyright
Other
Keywords
manned
Non-NASA Center
short duration
STS-95 Shuttle Project
Flight Experiment
NASA Discipline Plant Biology

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