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Changes in root cap pH are required for the gravity response of the Arabidopsis rootAlthough the columella cells of the root cap have been identified as the site of gravity perception, the cellular events that mediate gravity signaling remain poorly understood. To determine if cytoplasmic and/or wall pH mediates the initial stages of root gravitropism, we combined a novel cell wall pH sensor (a cellulose binding domain peptide-Oregon green conjugate) and a cytoplasmic pH sensor (plants expressing pH-sensitive green fluorescent protein) to monitor pH dynamics throughout the graviresponding Arabidopsis root. The root cap apoplast acidified from pH 5.5 to 4.5 within 2 min of gravistimulation. Concomitantly, cytoplasmic pH increased in columella cells from 7.2 to 7.6 but was unchanged elsewhere in the root. These changes in cap pH preceded detectable tropic growth or growth-related pH changes in the elongation zone cell wall by 10 min. Altering the gravity-related columella cytoplasmic pH shift with caged protons delayed the gravitropic response. Together, these results suggest that alterations in root cap pH likely are involved in the initial events that mediate root gravity perception or signal transduction.
Document ID
Document Type
Reprint (Version printed in journal)
External Source(s)
Fasano, J. M.
(University Park Pennsylvania 16802. United States)
Swanson, S. J.
Blancaflor, E. B.
Dowd, P. E.
Kao, T. H.
Gilroy, S.
Date Acquired
August 21, 2013
Publication Date
April 1, 2001
Publication Information
Publication: The Plant cell
Volume: 13
Issue: 4
ISSN: 1040-4651
Subject Category
Life Sciences (General)
Funding Number(s)
Distribution Limits
NASA Discipline Plant Biology
Non-NASA Center
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