Journal Article

Inhibitors of Ethylene Synthesis Inhibit Auxin-Induced Stomatal Opening in Epidermis Detached from Leaves of <i>Vicia Faba</i> L.

Frank Merritt, Andrea Kemper and Gary Tallman

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 42, issue 2, pages 223-230
Published in print February 2001 | ISSN: 0032-0781
Published online February 2001 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pce030
Inhibitors of Ethylene Synthesis Inhibit Auxin-Induced Stomatal Opening in Epidermis Detached from Leaves of Vicia Faba L.

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Using leaf epidermis from Vicia faba, we tested whether auxin-induced stomatal opening was initiated by auxin-induced ethylene synthesis. Epidermis was dark-incubated in buffered KNO3 containing 0.1 mM α-napthalene acetic acid or 1 mM indole-3-acetic acid. Maximum net opening was ca. 4 µm after 6 h. Opening was reversed by 20 µM ABA, 0.1 mM CaCl2. 1-Aminocyclopropane carboxylic acid (ACC) synthase catalyzes synthesis of ACC, the immediate precursor to ethylene. Auxin-induced stomatal opening was fully inhibited by 10 µM 1-aminoethoxyvinylglycine (AVG), an ACC synthase inhibitor. In solutions containing AVG, auxin-induced opening was restored in a concentration-dependent manner by exogenous ACC, but not in control solutions lacking an auxin. ACC-mediated reversal of AVG-inhibition of stomatal opening was inhibited by α-aminoisobutyric acid (AIB), an inhibitor of ACC oxidase, the last enzyme in the ethylene biosynthetic pathway, by 10 µM silver thiosulfate (STS), an inhibitor of ethylene action, and by 20 µM ABA, 0.1 mM CaCl2. CoCl2, an inhibitor of ethylene synthesis, also inhibited auxin-induced opening. Both STS and CoCl2 inhibited opening induced by light or by fusicoccin, but neither light- nor fusicoccin-induced opening was inhibited by AVG. These results support the hypothesis that auxin-induced stomatal opening is mediated through auxin-induced ethylene production by guard cells.

Keywords: Key words: Auxin — Ethylene — Guard cells — Stomata — Vicia faba.; Abbreviations: ACC, 1-aminocyclopropane carboxylic acid; AIB, α-aminoisobutyric acid; AVG, 1-aminoethoxyvinylglycine; NAA, α-napthalene acetic acid; SAM, S-adenosylmethionine; STS, silver thiosulfate.

Journal Article.  5919 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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