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Microsurgical removal of epidermal and cortical cells: evidence that the gravitropic signal moves through the outer cell layers in primary roots of maizeThere is general agreement that during root gravitropism some sort of growth-modifying signal moves from the cap to the elongation zone and that this signal ultimately induces the curvature that leads to reorientation of the root. However, there is disagreement regarding both the nature of the signal and the pathway of its movement from the root cap to the elongation zone. We examined the pathway of movement by testing gravitropism in primary roots of maize (Zea mays L.) from which narrow (0.5 mm) rings of epidermal and cortical tissue were surgically removed from various positions within the elongation zone. When roots were girdled in the apical part of the elongation zone gravitropic curvature occurred apical to the girdle but not basal to the girdle. Filling the girdle with agar allowed curvature basal to the girdle to occur. Shallow girdles, in which only two or three cell layers (epidermis plus one or two cortical cell layers) were removed, prevented or greatly delayed gravitropic curvature basal to the girdle. The results indicate that the gravitropic signal moves basipetally through the outermost cell layers, perhaps through the epidermis itself.
Document ID
20040090163
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
Authors
Yang, R. L.
(Ohio State University Columbus 43210, United States)
Evans, M. L.
Moore, R.
Date Acquired
August 21, 2013
Publication Date
January 1, 1990
Publication Information
Publication: Planta
Volume: 180
ISSN: 0032-0935
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: DMB8608673
CONTRACT_GRANT: NAGW-297
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Number 29-20
NASA Program Space Biology
Non-NASA Center
NASA Discipline Plant Biology

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