Date of Award

9-1-2025

Degree Type

Thesis

Degree Name

Master of Science (M.S.)

Department

Agricultural and Environmental Sciences

First Advisor

Dr Sonali Roy

Abstract

Nitrogen (N) is an essential but limiting macronutrient for crop growth in agroecosystems. Biological Nitrogen Fixation (BNF) is a critical biological process where atmospheric Nitrogen is converted into ammonia by Nitrogen fixing the bacteria called rhizobia, forming mutualistic relationships with legume plants. These interactions are mediated by several signaling pathways and may involve epigenetic modifications like DNA methylations, histone modifications, where gene expression is altered without any change in DNA sequence. Histones are proteins provide structural support to DNA. However, genes encoding enzymes for these post translational modifications are poorly investigated in the Leguminosae family. This project aims to answer question - Do peptide hormones alter the epigenetic landscape of the genome during root nodule symbiosis? Small, secreted peptides are important intercellular signaling molecules that regulate diverse biological processes. To this end, we identified 236 putative histone modifying enzyme encoding genes classified as Methyltransferases, Demethyltransferases, Acetyltransferases, Deacetyl transferases in the model legume Medicago truncatula. Next, we leveraged publicly available transcriptomic data to select a subset of genes differentially regulated during nodule formation and affected by peptide application. We initially selected four genes for CRISPR-Cas9-mediated editing to generate mutants, which would be examined for their phenotypes during nodulation. Among these, the PRAT1 (PEPTIDE RESPONSIVE ACETYLTRANSFERASE 1) gene was successfully edited, and screening of the transgenic lines identified a double mutant. This mutant will be phenotyped to understand its functional role during nodulation and peptide application. This research will uncover the role of histone modification genes in nitrogen fixation and peptide response.

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