Abscisic alcohol is an intermediate in abscisic acid biosynthesis in a shunt pathway from abscisic aldehyde

It has previously been shown that the abscisic acid (ABA)-deficient flacca and sitiens mutants of tomato are impaired in ABA-aldehyde oxidation and accumulate trans-ABA-alcohol as a result of the biosynthetic block (IB Taylor, RST Linforth, RJ Al-Naieb, WR Bowman, BA Marples [1988] Plant Cell Enviro...

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Published in:	Plant physiology (Bethesda) Vol. 97; no. 2; pp. 670 - 676
Main Authors:	ROCK, C. D, HEALTH, T. G, GAGE, D. A, ZEEVAART, J. A. D
Format:	Journal Article
Language:	English
Published:	Rockville, MD American Society of Plant Physiologists 01-10-1991
Subjects:	aba acide abscissique acido abscisico alcoholes alcohols alcool aldehidos aldehyde Aldehydes Atoms biochemical pathways Biological and medical sciences biosintesis biosynthese Biosynthesis Carbon monoxide Carboxyl compounds Fundamental and applied biological sciences. Psychology genetic variation Growth regulators Leaves Lycopersicon esculentum Metabolism mutant mutantes mutants Oxidases Oxidation Oxygen Plant physiology and development variacion genetica variation genetique via bioquimica del metabolismo voie biochimique du metabolisme Vegetable crop Radiolabelling Dicotyledones Angiospermae Lycopersicon esculentum Abscisic acid Plant growth substance Spermatophyta Biosynthesis Plant leaf Solanaceae Mutation
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Summary:	It has previously been shown that the abscisic acid (ABA)-deficient flacca and sitiens mutants of tomato are impaired in ABA-aldehyde oxidation and accumulate trans-ABA-alcohol as a result of the biosynthetic block (IB Taylor, RST Linforth, RJ Al-Naieb, WR Bowman, BA Marples [1988] Plant Cell Environ 11: 739-745). Here we report that the flacca and sitiens mutants accumulate trans-ABA and trans-ABA glucose ester and that this accumulation is due to trans-ABA biosynthesis. 18O labeling of water-stressed wild-type and mutant tomato leaves and analysis of [18O]ABA by tandem mass spectrometry show that the tomato mutants synthesize a significant percentage of their ABA and trans-ABA as [18O]ABA with two 18O atoms in the carboxyl group. We further show, by feeding experiments with [2H6]ABA-alcohol and 18O2 that this doubly-carboxyl-labeled ABA is synthesized from [18O]ABA-alcohol with incorporation of molecular oxygen. In vivo inhibition [2H6]ABA-alcohol oxidation by carbon monoxide establishes the involvement of a P-450 monooxygenase. Likewise, carbon monoxide inhibits the synthesis of doubly-carboxyl-labeled ABA in 18O-labeling experiments. This minor shunt pathway from ABA-aldehyde to ABA-alcohol to ABA operates in all plants examined. For the ABA-deficient mutants impaired in ABA-aldehyde oxidation, this shunt pathway is an important source of ABA and is physiologically significant.
Bibliography:	F60 F ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2
ISSN:	0032-0889 1532-2548
DOI:	10.1104/pp.97.2.670