A Role for Flavin Monooxygenase-Like Enzymes in Auxin Biosynthesis

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Science  12 Jan 2001:
Vol. 291, Issue 5502, pp. 306-309
DOI: 10.1126/science.291.5502.306

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Although auxin is known to regulate many processes in plant development and has been studied for over a century, the mechanisms whereby plants produce it have remained elusive. Here we report the characterization of a dominant Arabidopsis mutant,yucca, which contains elevated levels of free auxin.YUCCA encodes a flavin monooxygenase–like enzyme and belongs to a family that includes at least nine other homologousArabidopsis genes, a subset of which appears to have redundant functions. Results from tryptophan analog feeding experiments and biochemical assays indicate that YUCCA catalyzes hydroxylation of the amino group of tryptamine, a rate-limiting step in tryptophan-dependent auxin biosynthesis.

  • * Present address: Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, 2124 Life Sciences Box 951606, Los Angeles, CA 90095–1606, USA.

  • Present address: Department of Molecular Biology, 30 quai Ernest Ansermet, 1211 Geneve 4, Switzerland.

  • To whom correspondence should be addressed. E-mail: chory{at}

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