Effect of 2,4-dichlorophenoxyacetic acid on endogenous cyanide, beta-cyanoalanine synthase activity, and ethylene evolution in seedlings of soybean and barley

Treatment of etiolated seedlings of barley (Hordeum vulgare) and soybean (Glycine max) with 1 millimolar 2,4-dichlorophenoxyacetic acid (2,4-D) resulted in a 14-fold and greater than 100-fold increase in ethylene production, respectively. Simultaneous monitoring of endogenous cyanide and beta-cyanoa...

Full description

Saved in:
Bibliographic Details
Published in:Plant physiology (Bethesda) 1990-11, Vol.94 (3), p.1143-1148
Main Authors: Tittle, F.L. (Northern Alberta Institute of Technology, Edmonton, Alberta), Goudey, J.S, Spencer, M.S
Format: Article
Language:English
Subjects:
2,4-D
ACTIVIDAD ENZIMATICA
ACTIVITE ENZYMATIQUE
ALANINA
ALANINE
Barley
Biological and medical sciences
CIANUROS
Cyanides
CYANURE
Enzymes
ETHYLENE
Ethylene production
ETILENO
Fundamental and applied biological sciences. Psychology
GLYCINE MAX
Growth regulators
Herbicides
HORDEUM VULGARE
LIGASAS
LIGASE
Metabolism
Metabolism and Enzymology
METABOLISME
METABOLISMO
Nitrates
Plant growth
Plant physiology and development
Plants
PLANTULAS
PLANTULE
PRODUCCION VEGETAL
PRODUCTION VEGETALE
Seedlings
Soybeans
Citations: Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Treatment of etiolated seedlings of barley (Hordeum vulgare) and soybean (Glycine max) with 1 millimolar 2,4-dichlorophenoxyacetic acid (2,4-D) resulted in a 14-fold and greater than 100-fold increase in ethylene production, respectively. Simultaneous monitoring of endogenous cyanide and beta-cyanoalanine synthase (beta-CAS) (EC 4.4.1.9) activity was also performed. Endogenous levels of cyanide did not change in barley. In soybean, endogenous cyanide increased within 3 hours, increased again 6 hours after exposure to 2,4-D, and continued to increase throughout the experimental period. The activity of beta-CAS increased in both barley and soybean 9 hours after herbicide treatment. The increase in cyanide preceded the increase in beta-CAS activity by 3 to 6 hours in soybean. The steady-state concentration of endogenous cyanide in soybean was 1 micromolar, based on rates of ethylene production and cyanide metabolism by beta-CAS. This agreed with the determination of endogenous cyanide by both distillation and isotope dilution. Given the apparent compartmentalization of beta-CAS in mitochondria and the localization of ethylene/HCN production at the plasmalemma and/or tonoplast, our results suggest that extra-mitochondrial accumulation of cyanide in the cytoplasm may occur. If so, the activity of cyanide-sensitive cytoplasmic enzymes could be adversely affected, thus possibly contributing to the toxicity of 2,4-D
ISSN:0032-0889
1532-2548
DOI:10.1104/pp.94.3.1143