Reduced accumulation of ABA during water stress in a molybdenum cofactor mutant of barley

• Published in: Plant physiology (Bethesda) Vol. 90; no. 2; pp. 728 - 733
• Main Authors: Walker-Simmons, M. (USDA, ARS, Washington State University, Pullman, WA), Kudrna, D.A, Warner, R.L
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Physiologists 01-06-1989
• Subjects: ACIDE ABSCISSIQUE; ACIDO ABSCISICO; ACTIVIDAD ENZIMATICA; ACTIVITE ENZYMATIQUE; ALDEHIDOS; ALDEHYDE; Aldehydes; Barley; Biological and medical sciences; BIOSINTESIS; BIOSYNTHESE; COMPOSICION; COMPOSITION; Dehydration; Dehydrogenases; Fundamental and applied biological sciences. Psychology; Growth regulators; HORDEUM VULGARE; INHIBIDORES DE ENZIMAS; INHIBITEUR D'ENZYME; Leaves; Metabolism; MOLIBDENO; MOLYBDENE; MUTANT; MUTANTES; Nitrates; Oxidases; OXIDORREDUCTASAS; OXYDOREDUCTASE; Plant physiology and development; Plants; PRIVACION DEL AGUA; PRIVATION D'EAU; Seedlings; STRESS; TEMPERATURA; TEMPERATURE; Xanthines; Monocotyledones; Temperature; Hordeum vulgare; Water deficit; Biosynthesis; Metalloenzyme; Molybdenum; Stress; Enzymatic activity; Gramineae; Angiospermae; Abscisic acid; Plant growth substance; Spermatophyta; Mutation; Biological accumulation
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.90.2.728

A barley (Hordeum vulgare L.) mutant (Az34) has been identified with low basal levels of abscisic acid (ABA) and with reduced capacity for producing ABA in response to water stress. The mutation is in a gene controlling the molybdenum cofactor resulting in a pleiotropic deficiency in at least three molybdoenzymes, nitrate reductase, xanthine dehydrogenase, and aldehyde oxidase. The mutant was found to lack aldehyde oxidase activity with several substrates including: (a) ABA aldehyde, a putative precursor of ABA; (b) an acetylenic analog of ABAaldehyde; and (c) heptaldehyde. Elevating the growth temperature from 18 to 26 degrees C caused mutant leaves to wilt and brown. Desiccation of mutant leaves was prevented by applying ABA. These results indicate that ABA biosynthesis at some developmental stages is dependent upon a molybdoenzyme which may be an aldehyde oxidase