PLANT PHYSIOLOGY , Vol 104, Issue 1 271-276, Copyright © 1994 by American Society of Plant Biologists
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CELL BIOLOGY AND SIGNAL TRANSDUCTION |
Nutrient Uptake Changes in Ascorbate Free Radical-Stimulated Onion Roots
J. A. Gonzalez-Reyes, A. Hidalgo, J. A. Caler, R. Palos and P. Navas
Departamento de Biologia Celular, Universidad de Cordoba, 14004 Cordoba, Spain
Long-term treatments with ascorbate free radical-stimulated glucose,
fucose, sucrose, and nitrate uptake in Allium cepa roots. Glucose and
fucose showed saturation kinetics in untreated roots, but after treatment
with the ascorbate free radical, uptake was linear with time. Although the
rates of nitrate and sucrose uptake increased after treatment with
ascorbate free radical, the kinetics were similar to those observed in the
controls. Ascorbate and dehydroascorbate inhibited nutrient uptake. The
uptake rates for all nutrients increased throughout the 48-h period of
pretreatment with ascorbate free radical. During the treatment an increase
in the vacuole volume and tonoplast surface area also occurred. These
results show the relationship between an increase in vacuolar volume and
stimulated nutrient uptake from ascorbate-free radical, resulting in
enhanced root elongation. These results suggest that activation of a
transplasma membrane redox system by ascorbate-free radical is involved in
these responses.
