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G3 (Bethesda). 2016 May 3;6(5):1383-90. doi: 10.1534/g3.115.025585.

The Arabidopsis Auxin Receptor F-Box Proteins AFB4 and AFB5 Are Required for Response to the Synthetic Auxin Picloram.

Author information

1
Section of Cell and Developmental Biology and Howard Hughes Medical Institute, University of California San Diego, La Jolla, California 92093.
2
Department of Biology, Washington University, St. Louis, Missouri 63130.
3
Genomic Analysis Laboratory, Howard Hughes Medical Institute and The Salk Institute for Biological Studies, La Jolla, California 92037.
4
Section of Cell and Developmental Biology and Howard Hughes Medical Institute, University of California San Diego, La Jolla, California 92093 mestelle@ucsd.edu.

Abstract

The plant hormone auxin is perceived by a family of F-box proteins called the TIR1/AFBs. Phylogenetic studies reveal that these proteins fall into four clades in flowering plants called TIR1, AFB2, AFB4, and AFB6. Genetic studies indicate that members of the TIR1 and AFB2 groups act as positive regulators of auxin signaling by promoting the degradation of the Aux/IAA transcriptional repressors. In this report, we demonstrate that both AFB4 and AFB5 also function as auxin receptors based on in vitro assays. We also provide genetic evidence that AFB4 and AFB5 are targets of the picloram family of auxinic herbicides in addition to indole-3-acetic acid. In contrast to previous studies we find that null afb4 alleles do not exhibit obvious defects in seedling morphology or auxin hypersensitivity. We conclude that AFB4 and AFB5 act in a similar fashion to other members of the family but exhibit a distinct auxin specificity.

KEYWORDS:

Arabidopsis; F-box protein; auxin

PMID:
26976444
PMCID:
PMC4856089
DOI:
10.1534/g3.115.025585
[Indexed for MEDLINE]
Free PMC Article

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