Onion epidermis as a new model to study the control of growth anisotropy in higher plants

To elucidate the role of cellulose microfibrils in the control of growth anisotropy, a link between their net orientation, in vitro cell wall extensibility, and anisotropic cell expansion was studied during development of the adaxial epidermis of onion (Allium cepa) bulb scales using polarization co...

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Bibliographic Details
Published in:Journal of experimental botany 2009-01, Vol.60 (14), p.4175-4187
Main Authors: Suslov, Dmitry, Verbelen, Jean-Pierre, Vissenberg, Kris
Format: Article
Language:English
Subjects:
Anisotropy
Biological and medical sciences
Cell growth
cell wall
Cell walls
Cellulose - metabolism
Cellulose orientation
Epidermal cells
Epidermis
extensiometry
Fundamental and applied biological sciences. Psychology
growth anisotropy
Microfibrils - metabolism
Models, Biological
onion
Onions
Onions - genetics
Onions - growth & development
Onions - metabolism
Plant cells
Plant Epidermis - growth & development
Plant Epidermis - metabolism
Plant growth
Plants
Research Papers
Retraining
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Summary:To elucidate the role of cellulose microfibrils in the control of growth anisotropy, a link between their net orientation, in vitro cell wall extensibility, and anisotropic cell expansion was studied during development of the adaxial epidermis of onion (Allium cepa) bulb scales using polarization confocal microscopy, creep tests, and light microscopy. During growth the net cellulose alignment across the whole thickness of the outer epidermal wall changed from transverse through random to longitudinal and back to transverse relative to the bulb axis. Cell wall extension in vitro was always higher transverse than parallel to the net cellulose alignment. The direction of growth anisotropy was perpendicular to the net microfibril orientation and changed during development from longitudinal to transverse to the bulb axis. The correlation between the degree of growth anisotropy and the net cellulose alignment was poor. Thus the net cellulose microfibril orientation across the whole thickness of the outer periclinal epidermis wall defines the direction but not the degree of growth anisotropy. Strips isolated from the epidermis in the directions perpendicular and transverse to a net cellulose orientation can be used as an extensiometric model to prove a protein involvement in the control of growth anisotropy.
ISSN:0022-0957
1460-2431
DOI:10.1093/jxb/erp251