title: Auxin-induced ethylene biosynthesis in subapical stem sections of etiolated seedlings of Pisum sativum L.
abstract: 1-Aminocyclopropane-1-carboxylic acid (ACC) stimulated the production of ethylene in subapical stem sections of etiolated pea (cv. Alaska) seedlings in the presence and absence of indole-3-acetic acid (IAA). No lag period was evident following application of ACC, and the response was saturated at a concentration of 1 mM ACC. Levels of endogenous ACC paralleled the increase in ethylene production in sections treated with different concentrations of IAA and with selenoethionine or selenomethionine plus IAA. The IAA-induced formation of both ACC and ethylene was blocked by the rhizobitoxine analog aminoethoxyvinylglycine (AVG). Labelling studies with L-[U-(14)C]methionine showed an increase in the labelling of ethylene and ACC after treatment with IAA. IAA had no specific effect on the incorporation of label into S-methylmethionine or homoserine. The specific radioactivity of ethylene was similar to the specific radioactivity of carbon atoms 2 and 3 of ACC after treatment with IAA, indicating that all of the ethylene was derived from ACC. The activity of the ACC-forming enzyme was higher in sections incubated with IAA than in sections incubated with water alone. These results support the hypothesis that ACC is the in-vivo precursor of ethylene in etiolated pea tissue and that IAA stimulates ethylene production by increasing the activity of the ACC-forming enzyme.
authors: MSU-DOE Plant Research Laboratory, Michigan State University, 48824, East Lansing, MI, USA.
authors: J F
authors: JF
authors: Jones
authors: H
authors: H
authors: Kende