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Spatial separation of light perception and growth response in maize root phototropismAlthough the effects of gravity on root growth are well known and interactions between light and gravity have been reported, details of root phototropic responses are less documented. We used high-resolution image analysis to study phototropism in primary roots of Zea mays L. Similar to the location of perception in gravitropism, the perception of light was localized in the root cap. Phototropic curvature away from the light, on the other hand, developed in the central elongation zone, more basal than the site of initiation of gravitropic curvature. The phototropic curvature saturated at approximately 10 micromoles m-2 s-1 blue light with a peak curvature of 29 +/- 4 degrees, in part due to induction of positive gravitropism following displacement of the root tip from vertical during negative phototropism. However, at higher fluence rates, development of phototropic curvature is arrested even if gravitropism is avoided by maintaining the root cap vertically using a rotating feedback system. Thus continuous illumination can cause adaptation in the signalling pathway of the phototropic response in roots.
Document ID
20040088085
Acquisition Source
Ames Research Center
Document Type
Reprint (Version printed in journal)
Authors
Mullen, J. L.
(Indiana University Bloomington, IN 47405, United States)
Wolverton, C.
Ishikawa, H.
Hangarter, R. P.
Evans, M. L.
Date Acquired
August 21, 2013
Publication Date
September 1, 2002
Publication Information
Publication: Plant, cell & environment
Volume: 25
Issue: 9
ISSN: 0140-7791
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: NAG2-1411
CONTRACT_GRANT: NCC2-1200
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Plant Biology
Non-NASA Center

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