Dissecting the NCR Peptide Landscape in the R108 Ecotype in Medicago Truncatula and the Search for the NF21325 Symbiotic Mutant

Leguminous plants utilize Symbiotic Nitrogen Fixation (SNF) within root nodules to convert atmospheric nitrogen into bioavailable ammonium. In Medicago truncatula, nearly 700 Nodule-specific Cysteine-Rich (NCR) peptides regulate this process. This study investigates the R108 mutant line NF21325, featuring a Tnt1 insertion in MtNCR113. Inconsistent genotype-phenotype correlations and strain-specific responses with Sinorhizobium meliloti suggest a partial loss-of-function or complex genetic redundancy. To address R108’s limited genomic characterization, a bioinformatics pipeline identified novel NCR homologs and expanded the canonical NCR definition by uncovering non-cysteine peptides. Using homology-based clustering, R108 NCRs were organized into five distinct clades, revealing significant annotation gaps and sequence divergence compared to the A17 ecotype. Altogether, these findings emphasize the value of combining molecular, phenotypic, and computational approaches to dissect gene function in legume-rhizobia symbiosis, while also cautioning against oversimplified interpretations based on single-strain/method studies.

Name thesis:degree_name

Master of Science

Discipline thesis:degree_discipline

Biology

Grantor

Texas Woman's University

Year dc:date.issued

2026

Author dc:creator

• Howard, Erin

Advisor dc:contributor.advisor

• Pislariu, Catalina

Committee members dc:contributor.committeemember

• Maier, Camelia
• Brower, Christopher

• Nodule-specific cysteine-rich peptides
• Symbiotic nitrogen fixation
• Sinorhizobium meliloti
• Medicago truncatula

Language dc:language.iso

English

Handle dc:identifier.uri

https://hdl.handle.net/11274/17862

OAI identifier oai:identifier

oai:twu-ir.tdl.org:11274/17862