Nitrate-Induced MtCLE34 Gene Lacks the Ability to Reduce Symbiotic Nodule Number and Carries Nonsense Mutation in a Few Accessions of Medicago truncatula

Legume plants form nitrogen-fixing nodules on their roots in symbiosis with soil bacteria rhizobia. The number of symbiotic is controlled by a host plant via systemic mechanism known as autoregulation nodulation (AON). key players AON are the CLE peptides which produced root response to rhizobia inoculation and transported xylem shoot. In shoot, recognized CLV1-like receptor kinase, results subsequent inhibition nodule development negative feedback mechanism. addition induced rhizobia, nitrate-induced involved control have been identified. Medicago truncatula, MtCLE34 gene has described, was activated nitrate rhizobial inoculation. However, this contains premature stop codon reference M. truncatula genome A17 line, therefore, it suggested be pseudogene. Here, we analyzed nucleotide sequences available from genomes different accessions HAPMAP project found that majority accession lines do not carry nonsense mutations should encode functional products. Overexpression R108 does codon, did inhibit nodulation. Therefore, spite having high sequence similarity nodulation-suppressing genes, line able trigger truncatula. Our findings shed light evolutionary changes proteins legume can used future understand amino acid residues within could important for ability suppress