Honors Theses
Document Type
Thesis
Date of Completion
4-2024
Academic Year
2023-2024
Department
Biology
Academic Major
Molecular and Cellular Biology
Faculty Advisor
Rebekah Rampey, Ph.D.
Abstract
Plant development relies on cell proliferation, elongation, and differentiation to grow into a mature plant that is capable of competing for and procuring resources (Zluhan-Martínez et al., 2021). Plant hormones (phytohormones) including auxin (indole-3-acetic acid/IAA) regulate development and are tightly controlled by many proteins (Asami & Nakagawa, 2018; Claeys et al., 2014; Woodward & Bartel, 2005). One protein, IAA-Leucine Resistant3 (ILR3), is important in regulating IAA response within A. thaliana and represses the expression for different CCC1-like metal transporters (Rampey et al., 2006). By controlling metal transporters ILR3 is able to alter the metal microenvironment and indirectly effect the function of amidohydrolases, key enzymes in the conversion of storage forms of auxin (IAA-conjugates) and free auxin (Rampey et al., 2006). ILR3 is a bHLH-LZ TF and requires hetero- or homodimerization to function. A Yeast-2-Hybrid (Y2H) screen was used to identify possible dimerization partners of ILR3. One interactor identified, KUA1 (At5g47390), was further characterized through a series of directed screens and spotting assays. KUA1 was found to interact with ILR3 but was unable to interact with ilr3-1, supporting the necessity of the c-terminal region of ILR3 for dimerization. KUA1 has also been seen to address ROS homeostasis through regulating peroxidase expression and plants overexpressing KUA1 accumulate IAA (Lu et al., 2014; Kwon et al., 2013). Analysis of KUA1 interactions with ILR3 support KUA1 in playing a role in Fe and ROS levels in development, contributing to the phenotypic results seen in the gain-of-function ilr3-1 mutant (Kwon et al., 2013; Rampey et al., 2006). Furthermore, these results suggest ILR3 and KUA1 could be working in concert by managing Fe and ROS levels, resulting in altered IAA response and thereby plant development. KUA1 was also observed to interact with other bHLH proteins, suggesting a broader role of KUA1 in other plant processes. This study also identified two other proteins, ASIL1 and AR791, that were seen to interact with ILR3 and KUA1 and suggests the possibility of a protein complex in the regulation of free auxin in plant development.
Recommended Citation
McDonald, Tyler, "KUA1 and ILR3 Interact in _Arabidopsis thaliana_ to Mediate Plant Development" (2024). Honors Theses. 30.
https://scholarworks.harding.edu/honors-theses/30
