Auxin is a key hormone regulating plant growth and development. We combine experiments and mathematical modeling to reveal how auxin levels are maintained via feedback regulation of genes encoding key metabolic enzymes. We describe how regulation of auxin oxidation via transcriptional control of Arabidopsis thaliana gene DIOXYGENASE FOR AUXIN OXIDATION 1 (AtDAO1) expression is important at low to normal auxin concentrations. In contrast, higher auxin levels lead to increased Gretchen Hagen3 expression and auxin conjugation. Integrating this understanding into a multicellular model of root auxin dynamics successfully predicts that the dao1-1 mutant has an auxin-dependent longer root hair phenotype. Our findings reveal the importance of auxin homeostasis to maintain this hormone at optimal levels for plant growth and development.
Mellor, N. L., Band, L. R., Pěnčík, A., Novak, O., Rashed, A., Holman, T., …Owen, M. R. (2016). Dynamic regulation of auxin oxidase and conjugating enzymes AtDAO1 and GH3 modulates auxin homeostasis. Proceedings of the National Academy of Sciences, 113(39), 11022-11027. https://doi.org/10.1073/pnas.1604458113