Compensatory Mutations in Predicted Metal Transporters Modulate Auxin Conjugate Responsiveness in Arabidopsis

Rebekah A Rampey, Megan T Baldridge, David C Farrow, Sarah N Bay, Bonnie Bartel

Research output: Contribution to journalArticlepeer-review

Abstract

Levels of the phytohormone indole-3-acetic acid (IAA) can be altered by the formation and hydrolysis of IAA conjugates. The isolation and characterization of Arabidopsis thaliana mutants with reduced IAA-conjugate sensitivity and wild-type IAA responses is advancing the understanding of auxin homeostasis by uncovering the factors needed for conjugate metabolism. For example, the discovery that the IAA-Ala-resistant mutant iar1 is defective in a protein in the ZIP family of metal transporters uncovered a link between metal homeostasis and IAA-conjugate sensitivity. To uncover additional factors impacting auxin conjugate metabolism, we conducted a genetic modifier screen and isolated extragenic mutations that restored IAA-amino acid conjugate sensitivity to the iar1 mutant. One of these suppressor mutants is defective in a putative cation diffusion facilitator, MTP5 (At3g12100; formerly known as MTPc2). Loss of MTP5 function restored IAA conjugate sensitivity to iar1 but not to mutants defective in IAA-amino acid conjugate amidohydrolases. Our results are consistent with a model in which MTP5 and IAR1 transport metals in an antagonistic fashion to regulate metal homeostasis within the subcellular compartment in which the IAA-conjugate amidohydrolases reside, and support previous suggestions that the ion composition in this compartment influences hydrolase activity.

Original languageAmerican English
JournalG3: Genes, Genomes, Genetics
Volume3
DOIs
StatePublished - Jan 1 2013

Keywords

  • MTP5
  • IAR1
  • Auxin conjugates
  • Metal Transport
  • Arabidopsis

Disciplines

  • Biology

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