Trp-dependent auxin biosynthesis in Arabidopsis: involvement of cytochrome P450s CYP79B2 and CYP79B3

The plant hormone auxin regulates many aspects of plant growth and development. Although several auxin biosynthetic pathways have been proposed, none of these pathways has been precisely defined at the molecular level. Here we provide in planta evidence that the two Arabidopsis cytochrome P450s, CYP...

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Bibliographic Details
Published in:Genes & development 2002-12, Vol.16 (23), p.3100-3112
Main Authors: Zhao, Yunde, Hull, Anna K, Gupta, Neeru R, Goss, Kendrick A, Alonso, José, Ecker, Joseph R, Normanly, Jennifer, Chory, Joanne, Celenza, John L
Format: Article
Language:English
Subjects:
Arabidopsis - enzymology
Arabidopsis - metabolism
Cytochrome P-450 Enzyme System - metabolism
Indoleacetic Acids - biosynthesis
Indoleacetic Acids - metabolism
Indoles - metabolism
Mutation
Oximes - metabolism
Phenotype
Research Paper
Tryptophan - metabolism
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Summary:The plant hormone auxin regulates many aspects of plant growth and development. Although several auxin biosynthetic pathways have been proposed, none of these pathways has been precisely defined at the molecular level. Here we provide in planta evidence that the two Arabidopsis cytochrome P450s, CYP79B2 and CYP79B3, which convert tryptophan (Trp) to indole-3-acetaldoxime (IAOx) in vitro, are critical enzymes in auxin biosynthesis in vivo. IAOx is thus implicated as an important intermediate in auxin biosynthesis. Plants overexpressing CYP79B2 contain elevated levels of free auxin and display auxin overproduction phenotypes. Conversely, cyp79B2 cyp79B3 double mutants have reduced levels of IAA and show growth defects consistent with partial auxin deficiency. Together with previous work on YUCCA, a flavin monooxygenase also implicated in IAOx production, and nitrilases that convert indole-3-acetonitrile to auxin, this work provides a framework for further dissecting auxin biosynthetic pathways and their regulation.
ISSN:0890-9369
1549-5477
DOI:10.1101/gad.1035402