Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.

Science 3 April 1981:
Vol. 212. no. 4490, pp. 70 - 71
DOI: 10.1126/science.212.4490.70
Prev | Table of Contents | Next

Articles

Geotropism in Corn Roots: Evidence for Its Mediation by Differential Acid Efflux

TIMOTHY J. MULKEY 1 and MICHAEL L. EVANS 1

1 Department of Botany, Ohio State University, Columbus 43210

The elongation zone in intact growing corn roots secretes acid leading to a reduced pH along the surface of the root and in the adjacent medium. This can be detected by placing the root on an agar medium containing the pH indicator dye bromocresol purple. When the root is treated with a growth inhibitory concentration of the hormone indole-3-acetic acid, the acid efflux is reversed and growth is greatly retarded. When the root is mounted vertically, acid secretion is uniform along the elongation zone, and the root grows straight downward. When the root is placed horizontally, there is enhanced acid efflux along the upper surface of the elongation zone and reduced acid efflux along the lower surface. An increased rate of elongation of the upper cells relative to the lower cells then results in downward curvature of the root. The correlation between acid efflux patterns and growth patterns indicates that proton efflux is important in the control of root growth.

Submitted on September 15, 1980
Revised on December 5, 1980


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Production of Reactive Oxygen Intermediates (O2{middle dot}-, H2O2, and {middle dot}OH) by Maize Roots and Their Role in Wall Loosening and Elongation Growth.
A. Liszkay, E. van der Zalm, and P. Schopfer (2004)
Plant Physiology 136, 3114-3123
   Abstract »    Full Text »    PDF »
Transcription Profiling of the Early Gravitropic Response in Arabidopsis Using High-Density Oligonucleotide Probe Microarrays.
N. Moseyko, T. Zhu, H.-S. Chang, X. Wang, and L. J. Feldman (2002)
Plant Physiology 130, 720-728
   Abstract »    Full Text »    PDF »
Changes in Root Cap pH Are Required for the Gravity Response of the Arabidopsis Root.
J. M. Fasano, S. J. Swanson, E. B. Blancaflor, P. E. Dowd, T.-h. Kao, and S. Gilroy (2001)
PLANT CELL 13, 907-922
   Abstract »    Full Text »
Salinity-Induced Inhibition of Leaf Elongation in Maize Is Not Mediated by Changes in Cell Wall Acidification Capacity.
B. G. Neves-Piestun and N. Bernstein (2001)
Plant Physiology 125, 1419-1428
   Abstract »    Full Text »
The Arabidopsis thaliana AGRAVITROPIC 1 gene encodes a component of the polar-auxin-transport efflux carrier.
R. Chen, P. Hilson, J. Sedbrook, E. Rosen, T. Caspar, and P. H. Masson (1998)
PNAS 95, 15112-15117
   Abstract »    Full Text »    PDF »
Localized changes in apoplastic and cytoplasmic pH are associated with root hair development in Arabidopsis thaliana.
T. Bibikova, T Jacob, I Dahse, and S Gilroy (1998)
Development 125, 2925-2934
   Abstract »    PDF »


To Advertise     Find Products

Science. ISSN 0036-8075 (print), 1095-9203 (online)