PLANT PHYSIOLOGY , Vol 105, Issue 4 1133-1138, Copyright © 1994 by American Society of Plant Biologists
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ENVIRONMENTAL AND STRESS PHYSIOLOGY |
Iron-Deficiency Stress Responses in Cucumber (Cucumis sativus L.) Roots (A Possible Role for Ethylene?)
F. J. Romera and E. Alcantara
Department of Agronomy, Escuela T. S. Ingenieros Agronomos y de Montes, University of Cordoba, Apdo. 3048, 14080 Cordoba, Spain
Most dicotyledonous species respond to Fe deficiency by developing several
mechanisms known as Fe-deficiency stress responses. To study the regulation
of these responses, young cucumber plants (Cucumis sativus L. cv Ashley)
were grown in nutrient solution for 11 d, being deprived of Fe during the
last 4 or 5 d. Inhibitors of ethylene synthesis (2 or 10 [mu]M
aminoethoxyvinylglycine; 10 or 20 [mu]M aminooxyacetic acid; 1, 2, 5, or 10
[mu]M Co2+ as CoCl2) or action (50, 200, or 800 [mu]M Ag+ as silver
thiosulfate) were added to the nutrient solution at different times during
this period of growth with no Fe. After this period, the reduction of Fe3+
ethylenedi-aminetetraacetate by the roots of entire plants was measured
with ferrozine by reading the absorbance at 562 nm after 2 h. The presence
of the ethylene inhibitors in the nutrient solution inhibited the
Fe-deficiency stress responses ferric-reducing capacity and subapical root
swelling. In another experiment, the addition of 1 [mu]M
1-aminocyclopropane-1-carboxylic acid (ACC), a precursor of ethylene
synthesis, to the nutrient solution of plants having low ferric-reducing
activity increased notably the ferric-reducing capacity and subapical root
swelling. Here we show evidence that ethylene plays a role in the
development of Fe-deficiency stress responses, since when ethylene
synthesis or action was inhibited, the responses were also inhibited, and
when a precursor of ethylene (ACC) was added, the responses were increased.
