Abstract
The herbicide 2,4-D exhibits an auxinic activity and therefore can be used as a synthetic and traceable analog to study auxin-related responses. Here we identified that not only exogenous 2,4-D but also its amide-linked metabolite 2,4-D-Glu displayed an inhibitory effect on plant growth via the TIR1/AFB auxin-mediated signaling pathway. To further investigate 2,4-D metabolite conversion, identity and activity, we have developed a novel purification procedure based on the combination of ion exchange and immuno-specific sorbents combined with a sensitive liquid chromatography-mass spectrometry method. In 2,4-D treated samples, 2,4-D-Glu and 2,4-D-Asp were detected at 100-fold lower concentrations compared to 2,4-D levels, showing that 2,4-D can be metabolized in the plant. Moreover, 2,4-D-Asp and 2,4-D-Glu were identified as reversible forms of 2,4-D homeostasis that can be converted to free 2,4-D. This work paves the way to new studies of auxin action in plant development.
MeSH terms
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2,4-Dichlorophenoxyacetic Acid / pharmacology*
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Arabidopsis / drug effects
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Arabidopsis / growth & development
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Arabidopsis / metabolism*
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Arabidopsis Proteins / genetics
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Arabidopsis Proteins / metabolism
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F-Box Proteins / genetics
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F-Box Proteins / metabolism
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Gene Expression Regulation, Plant
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Herbicides / pharmacology
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Homeostasis
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Indoleacetic Acids / metabolism*
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Plant Growth Regulators / pharmacology
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Plant Roots / drug effects
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Plant Roots / growth & development
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Plant Roots / metabolism*
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Receptors, Cell Surface / genetics
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Receptors, Cell Surface / metabolism
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Seedlings / drug effects
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Seedlings / growth & development
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Seedlings / metabolism
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Signal Transduction / drug effects
Substances
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Arabidopsis Proteins
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F-Box Proteins
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Herbicides
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Indoleacetic Acids
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Plant Growth Regulators
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Receptors, Cell Surface
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TIR1 protein, Arabidopsis
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2,4-Dichlorophenoxyacetic Acid
Grants and funding
This work was funded by the Czech Science Foundation (Nr. GA14-34792S; ON, JO, BP), by the Ministry of Education, Youth and Sports of the Czech Republic – NPU I program with projects LO1204 (ON, JO, HK, TP, MS) and LO1218 (LE, MF), the ‘‘Návrat’’ program LK21306 (ON, JO), by the Internal Grant Agency of Palacký University (Nr. IGA_PrF_2016_011; BP, HK), by Vetenskapsrådet and VINNOVA (TV, SR), IWT agency for innovation by science and technology (EB), and by the Vienna Science and Technology Fund (WWTF) Vienna Research Group program (JK-V), Austrian Science Fund (FWF) (P26568-B16 and P26591-B16) (JK-V), and the European Research Council (ERC) Starting Grant 639478-AuxinER (JK-V).