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Reassessing the role of N-Hydroxytryptamine in auxin biosynthesis
journal contribution
posted on 2023-05-17, 04:45 authored by Nathan TivendaleNathan Tivendale, Noel DaviesNoel Davies, Molesworth, PP, Davidson, SE, Jason SmithJason Smith, Lowe, EK, James ReidJames Reid, John RossJohn RossThe tryptamine pathway is one of five proposed pathways for the biosynthesis of indole-3-acetic acid (IAA), the primary auxin in plants. The enzymes AtYUC1 (Arabidopsis thaliana), FZY (Solanum lycopersicum), and ZmYUC (Zea mays) are reported to catalyze the conversion of tryptamine to N-hydroxytryptamine, putatively a rate-limiting step of the tryptamine pathway for IAA biosynthesis. This conclusion was based on in vitro assays followed by mass spectrometry or HPLC analyses. However, there are major inconsistencies between the mass spectra reported for the reaction products. Here, we present mass spectral data for authentic N-hydroxytryptamine, 5-hydroxytryptamine (serotonin), and tryptamine to demonstrate that at least some of the published mass spectral data for the YUC in vitro product are not consistent with N-hydroxytryptamine. We also show that tryptamine is not metabolized to IAA in pea (Pisum sativum) seeds, even though a PsYUC-like gene is strongly expressed in these organs. Combining these findings, we propose that at present there is insufficient evidence to consider N-hydroxytryptamine an intermediate for IAA biosynthesis.
History
Publication title
Plant PhysiologyVolume
154Issue
4Pagination
1957-1965ISSN
0032-0889Department/School
School of Natural SciencesPublisher
Amer Soc Plant BiologistsPlace of publication
15501 Monona Drive, Rockville, USA, Md, 20855Rights statement
Copyright © 2010 by the American Society of Plant BiologistsRepository Status
- Restricted