Uncovering New Mechanisms for Indole-3-butyric Acid Metabolism and Transport in Arabidopsis thaliana

Author

Arielle Lynne Homayouni, Washington University in St. LouisFollow

ORCID

http://orcid.org/0000-0002-3934-7242

Date of Award

Winter 12-15-2022

Author's School

Graduate School of Arts and Sciences

Author's Department

Biology & Biomedical Sciences (Molecular Genetics & Genomics)

Degree Name

Doctor of Philosophy (PhD)

Degree Type

Dissertation

Abstract

The phytohormone auxin acts as an essential regulator of plant growth and development through its mediation of cell division, elongation, and differentiation. Proper spatiotemporal distribution of auxin within a plant is regulated on a cellular level and is critical to ensuring precise organ morphogenesis and physiology. The proper level and distribution of active auxin (indole-3-acetic acid, IAA) is tightly regulated via de novo synthesis, transport, and conversion from its conjugated forms and precursors. Studies in Arabidopsis have revealed the importance of one such precursor, indole-3-butyric acid (IBA), in regulation of auxin homeostasis. Unlike IAA, the mechanism for IBA transport and metabolism is not well defined. In this work, we describe the studies we undertook to demonstrate and identify novel roles for factors involved in modulating IBA contributions to the active auxin pool via IBA transport or regulation of IBA conjugation. First, an IBA transporter was identified and characterized for its roles in regulating root apical meristem length and leaf size. Next, an E3-ubiquitin ligase F-Box protein and its putative targets were examined for their previously undefined roles in regulating auxin homeostasis through modulation of IBA contributions to the active auxin pool via degradation of IBA conjugating enzymes. Together, this work uncovers previously uncharacterized mechanisms governing IBA transport and metabolism in Arabidopsis and provides a stronger understanding of the roles and significance of IBA transport and IBA contributions to the active auxin pool to influence auxin homeostasis.

Language

English (en)

Chair and Committee

Lucia Strader

Committee Members

Michael Nonet

Comments

Update embargo

Recommended Citation

Homayouni, Arielle Lynne, "Uncovering New Mechanisms for Indole-3-butyric Acid Metabolism and Transport in Arabidopsis thaliana" (2022). Arts & Sciences Electronic Theses and Dissertations. 2737.
https://openscholarship.wustl.edu/art_sci_etds/2737