Abstract

Nitrogen fertilizers are an irreplaceable component of modern agriculture. However, due to the inefficiency of the crops bred, up to 70% of the applied nitrogen is not absorbed, and the resulting runoff creates environmental pollution. Roots play a crucial role in a plant's well-being by absorbing nutrients and water and providing anchorage. The efficiency of these functions is significantly influenced by both the physiology and architecture of the roots. However, compared to above-ground parts, roots are understudied due to the inaccessibility of the organ and the complexity of the structure. This is particularly true for the genes underlying root system architecture, which remain largely unidentified due to the challenges associated with accurately capturing and measuring their complex morphological traits. In this dissertation, we identify E1OGDH1 as a mediator of Root System Architecture (RSA) and attempt to provide a hypothesis on the molecular mechanism using multi-omic studies. In Chapter 2, we delve into the process of identifying E1OGDH1 and characterize root crowns, focusing on the impact of natural and artificial alleles of the gene. Initially, we identify E1OGDH1 through Genome-Wide Association Studies (GWAS) of root crowns from a population specifically selected for high and low protein content in kernels, known as the Illinois Long Term Protein Selection Strains (ILTPS) population. We conducted two field experiments using recombinant inbred lines from the ILTPS population and phenotyped their root crowns using X-ray computed tomography. Additionally, we generated mutants in a B73 background and conducted a field experiment under nitrogen stress conditions. The CRISPR mutants employed a different root system architecture (RSA) strategy under nitrogen stress compared to the wild type. Our findings from the root crown phenotyping indicate that E1OGDH1 is mediating root architecture and nitrogen response. In Chapter 3, we utilize CRISPR mutants of E1OGDH1 grown under both high and low nitrogen conditions to conduct targeted metabolomics and transcriptomics studies. We collect leaf and root tissues from both wild-type and E1OGDH1 mutant plants and perform mass spectrometry to analyze TCA cycle organic acids, glycolytic metabolites, and free amino acids. Additionally, we conduct RNA sequencing (RNAseq) for transcriptomic analysis using these tissues. These comprehensive analyses provide valuable insights into the molecular mechanisms driving changes in RSA and responses to nitrogen stress. Overall, this work significantly advances our understanding of the role of E1OGDH1 in RSA and nitrogen stress response.

Committee Chair

Christopher Topp

Committee Members

Barbara Kunkel; Douglas Allen; Ivan Baxter; Kevin Cox

Degree

Doctor of Philosophy (PhD)

Author's Department

Biology & Biomedical Sciences (Plant & Microbial Biosciences)

Author's School

Graduate School of Arts and Sciences

Document Type

Dissertation

Date of Award

12-15-2025

Language

English (en)

Author's ORCID

0009-0007-0964-7424

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Available for download on Saturday, December 12, 2026

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Biology Commons

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