PT  - JOURNAL ARTICLE
AU  - Mullen, Jack L.
AU  - Turk, Ed
AU  - Johnson, Karin
AU  - Wolverton, Chris
AU  - Ishikawa, Hideo
AU  - Simmons, Carl
AU  - Söll, Deiter
AU  - Evans, Michael L.
TI  - Root-Growth Behavior of the Arabidopsis Mutant<em>rgr1</em>
AID  - 10.1104/pp.118.4.1139
DP  - 1998 Dec 01
TA  - Plant Physiology
PG  - 1139--1145
VI  - 118
IP  - 4
4099  - http://www.plantphysiol.org/content/118/4/1139.short
4100  - http://www.plantphysiol.org/content/118/4/1139.full
SO  - Plant Physiol.1998 Dec 01; 118
AB  - In this study we investigated the kinetics of the gravitropic response of the Arabidopsis mutant rgr1 (reducedroot gravitropism). Although the rate of curvature in rgr1, which is allelic toaxr4, was smaller than in the wild type (ecotype Wassilewskija), curvature was initiated in the same region of the root, the distal elongation zone. The time lag for the response was unaffected in the mutant; however, the gravitropic response ofrgr1 contained a feature not found in the wild type: when roots growing along the surface of an agar plate were gravistimulated, there was often an upward curvature that initiated in the central elongation zone. Because this response was dependent on the tactile environment of the root, it most likely resulted from the superposition of the waving/coiling phenomenon onto the gravitropic response. We found that the frequency of the waving pattern and circumnutation, a cyclic endogenous pattern of root growth, was the same in rgr1 and in the wild type, so the waving/coiling phenomenon is likely governed by circumnutation patterns. The amplitudes of these oscillations may then be selectively amplified by tactile stimulation to provide a directional preference to the slanting.