Iron requirement for and effects of promoters and inhibitors of ethylene action on stimulation of Fe(III)-chelate reductase in roots of strategy I species
✍ Scribed by Francisco J. Romera; Ross M. Welch; Wendell A. Norvell; Stephen C. Schaefer
- Publisher
- Springer Netherlands
- Year
- 1996
- Tongue
- English
- Weight
- 465 KB
- Volume
- 9
- Category
- Article
- ISSN
- 1572-8773
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✦ Synopsis
Stimulation of root Fe(lll) reductase activity by iron additions to iron-deficient growth media may be the result of iron activation of I-aminocyclopropane-l-carboxylic acid (ACC) oxidase required for ethylene biosynthesis. Two different ethylene inhibitors, aminooxyacetic acid (AOA) (20 pM; ACC synthase inhibitor) and cobalt (3 pM COCI2; ACC oxidase inhibitor), were used to study the effects of iron supply and cobalt inhibition on ethylene action in controlling the activity of Fe(lll)-chelate reductase in pea (Pisum sativum L.) roots. Supplying 20 ~M Fe(lll)-N,/V-ethylenebis[2-(2-hydroxypheyl)-glycine [Fe(III)-EDDHA] to either cobalt-treated, iron-deficient Sparkle (normal parent) or El07 (brz mutant genotype) pea seedlings reversed the negative effects of cobalt on root Fe(lll)-reductase activity. Re-supplying 20 ~M Fe(III)-EDDHA to iron-deficient, AOA-treated seedlings did not enhance root (Fe(lll)-reductase. Apparently, cobalt competes with iron for the active site in ACC oxidase during ethylene synthesis. Inhibition of root reductase activity by cobalt treatment lowered manganese, zinc, magnesium and potassium content of mutant El07 pea seedlings. In contrast, iron enhancement of root reductase activity in iron-deficient, cobalt-treated El07 seedlings resulted in higher seedling accumulations of manganese, zinc, magnesium and potassium. These results support the hypothesis that root cell plasma membrane reduetase activity plays a role in cation uptake by root cells.