Speaker: Linkan Dash, graduate student in Kelley Lab

Major: Genetics and Genomics

Major professor: GDCB Assistant Professor Dior Kelley

Department: Genetics, Development and Cell Biology

Title: "The role of auxin regulated proteins in Arabidopsis and maize root development"

Abstract: Auxin is a key plant hormone with significant roles in regulating diverse aspects of plant development including root formation, environmental stress responses, gravitropism, and phototropism, establishing bilateral symmetry in the embryo and apical dominance ​(Brumos et al., 2018; Yu et al., 2022)​. It is of great interest for us to decipher the molecular mechanisms underpinning these physiological processes. Through this dissertation, I have investigated three main knowledge gaps related to plant auxin pathways. My first study utilized the Arabidopsis hypocotyl (embryonic stem) system to characterize novel protein function downstream of auxin signaling during cell elongation. Here, I examined the synergistic role of AUXIN RESPONSE FACTORs (ARFs) and PHYTOCHROME INTERACTING FACTORs (PIFs) in constituting a core transcription factor module that controls Arabidopsis hypocotyl elongation. Below ground, the Arabidopsis root system provides us with genetic and microscopic advantages. I studied a pectin-synthesizing enzyme called GALACTURONOSYL TRANSFERASE 10 (GAUT10), which is post-transcriptionally inhibited by auxin, to establish a mechanistic link between the auxin and cell wall properties within the primary root. This work shows how Arabidopsis root cell wall composition is affected by the loss of GAUT10, whereby Rhamnogalacturonans (RGs) and Homogalacturonans (HGs) are specifically altered, conferring negative feedback on auxin signaling and metabolism. Lastly, I investigated how auxin transcriptionally reprograms maize roots and used a computational approach to infer which specific transcription factors are involved in this process. I initially identified and attributed a maize ARF, ZmARF27, which is required for root morphogenesis and proper gene expression patterns. Through collaboration I later unraveled ZmARF27 gene targets using quantitative genetics and network analyses. This study exemplifies my ability to conduct team science. The data exhibits spatiotemporal auxin-mediated gene regulation within primary maize roots and establishes a key role for ZmARF27 in maize root development via transcriptional regulation.