Auxin molecular field maps define AUX1 selectivity: many auxin herbicides are not substrates
Language English Country England, Great Britain Media print-electronic
Document type Journal Article, Research Support, Non-U.S. Gov't
Grant support
BB/G023972/1
Biotechnology and Biological Sciences Research Council - United Kingdom
BB/L001489/1
Biotechnology and Biological Sciences Research Council - United Kingdom
PubMed
29265374
DOI
10.1111/nph.14950
Knihovny.cz E-resources
- Keywords
- auxin transport, cheminformatics, herbicide, herbicide resistance, molecular field maps, pharmacophore, structure-activity relationship, uptake carrier,
- MeSH
- Arabidopsis metabolism MeSH
- Models, Biological MeSH
- Biological Assay MeSH
- Herbicides metabolism MeSH
- Indoles metabolism MeSH
- Inhibitory Concentration 50 MeSH
- Plant Roots growth & development MeSH
- 2,4-Dichlorophenoxyacetic Acid metabolism MeSH
- Indoleacetic Acids metabolism MeSH
- Mutation genetics MeSH
- Arabidopsis Proteins metabolism MeSH
- Seedlings growth & development MeSH
- Substrate Specificity MeSH
- Nicotiana cytology MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- AUX1 protein, Arabidopsis MeSH Browser
- Herbicides MeSH
- Indoles MeSH
- 2,4-Dichlorophenoxyacetic Acid MeSH
- Indoleacetic Acids MeSH
- Arabidopsis Proteins MeSH
Developmental responses to auxin are regulated by facilitated uptake and efflux, but detailed molecular understanding of the carrier proteins is incomplete. We have used pharmacological tools to explore the chemical space that defines substrate preferences for the auxin uptake carrier AUX1. Total and partial loss-of-function aux1 mutants were assessed against wild-type for dose-dependent resistance to a range of auxins and analogues. We then developed an auxin accumulation assay with associated mathematical modelling to enumerate accurate IC50 values for a small library of auxin analogues. The structure activity relationship data were analysed using molecular field analyses to create a pharmacophoric atlas of AUX1 substrates. The uptake carrier exhibits a very high level of selectivity towards small substrates including the natural indole-3-acetic acid, and the synthetic auxin 2,4-dichlorophenoxyacetic acid. No AUX1 activity was observed for herbicides based on benzoic acid (dicamba), pyridinyloxyacetic acid (triclopyr) or the 6-arylpicolinates (halauxifen), and very low affinity was found for picolinic acid-based auxins (picloram) and quinolinecarboxylic acids (quinclorac). The atlas demonstrates why some widely used auxin herbicides are not, or are very poor substrates. We list molecular descriptors for AUX1 substrates and discuss our findings in terms of herbicide resistance management.
Rothamsted Research Harpenden AL5 2JQ UK
School of Life Sciences University of Warwick Gibbet Hill Road Coventry CV4 7AL UK
References provided by Crossref.org
Advances in Understanding the Mechanism of Action of the Auxin Permease AUX1
