ASGSB 1999 Annual Meeting Abstracts

ELECTROTROPISM INDICATES TWO PHYSIOLOGICALLY DISTINCT RESPONSE ZONES IN THE ROOT. C. Wolverton, J.L. Mullen, M.L. Evans, and H. Ishikawa. Dept. of Plant Biology, The Ohio State University, Columbus, OH.

Vertical roots generate a characteristic pattern of current flow that changes upon stimulation to horizontal. To probe the role of this pattern change as it relates to the gravity response, we applied an electric field to vertical roots of mung bean (Vigna mungo) and analyzed the response with custom software. In a homogeneous field responses were characterized as biphasic, with apparently opposite contributions from the central elongation zone [CEZ] and distal elongation zone [DEZ]. Curvature in the CEZ was toward the positive electrode, while curvature in the DEZ was toward the negative electrode. Further characterization of this response was pursued through application of a localized electric field and a microgravity experiment aboard STS-95. Localized application of the field with a microelectrode indicated two regions in the root that responded oppositely, as with homogeneous field application. In microgravity, application of a field that induced curvature in 1 g resulted in inhibition of elongation.

(Supported by NASA: NGT5-50015, NAG5-6385, and the NASA/NSF Joint Program in Plant Biology, Network for Research on Plant Sensory Systems IBN-9421856)

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