Characterization of the Asymmetric Growth of Gravistimulated Snapdragon Spikes by Stem and Cell Dimension Analyses

Growth patterns of detached spikes of gravistimulated snapdragon (Antirrhinum majus L.) were analyzed in detail. The length increment of 5-mm marked subsections in the upper and lower flanks of the stem-bending zone was measured during gravistimulation using time-lapse photographs. At the onset of b...

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Bibliographic Details
Published in:American journal of botany 2003-06, Vol.90 (6), p.849-856
Main Authors: Friedman, Haya, Shimon Meir, Halevy, Abraham H., Sonia Philosoph-Hadas
Format: Article
Language:English
Subjects:
Antirrhinum majus cut spikes
Bending
bending zone
Botany
Calcium
calcium antagonists
Cell growth
Coleoptiles
cortex
Curvature
Epidermal cells
Epidermis
epidermis cells
Flowers & plants
lower and upper flanks
Physiology and Development
Plant growth
Plant physiology
Plants
relative growth rate
shrinkage
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Summary:Growth patterns of detached spikes of gravistimulated snapdragon (Antirrhinum majus L.) were analyzed in detail. The length increment of 5-mm marked subsections in the upper and lower flanks of the stem-bending zone was measured during gravistimulation using time-lapse photographs. At the onset of bending, a negative relative growth rate of the upper flank was detected, followed by increased relative growth rate in both lower and upper flanks. Consequently, a differential stem growth pattern was obtained during gravistimulation, which was significantly and specifically abolished by calcium antagonists reported previously to inhibit stem curvature of snapdragon. The differential growth patterns resulted from dynamic modifications of the cell dimensions in the epidermal and cortical stem layers. Bending started with both shrinking and widening of the epidermal cells and a parallel decrease in length and height of cortical cells at the upper stem flank. These changes were accompanied with a concomitant increase in length and height of the cortical cells on the lower stem flank, followed by a growth increase of epidermal cells. Our results suggest that both the epidermal and cortical cells play an important role in gravitropic shoot bending of snapdragon.
ISSN:0002-9122
1537-2197
DOI:10.3732/ajb.90.6.849