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