Exploring the NF-YC gene family in Astragalus membranaceus: characterization, evolutionary relationships, and expression pattern analysis under MeJA treatment

Astragalus membranaceus, a leguminous herb native to East Asia, is renowned for its rich content of bioactive compounds, particularly triterpenoid saponins and flavonoids, within its roots. Nuclear factor Y (NF-Y) is a key transcription factor family in eukaryotes, known to regulate abiotic stress responses in plants by binding to the CCAAT-box motif in promoter regions. Despite its significance, the NF-Y gene family has not been systematically identified in A. membranaceus prior to this study. Here, we identified 34 AmNF-YC genes from the A. membranaceus genome and characterized their gene lengths, domain architectures, and amino acid sizes. Phylogenetic analysis classified the AmNF-YC members into three distinct subfamilies (I, II, and III). Notably, proteins within the same clade exhibited conserved motif structures, suggesting that evolutionary relatedness may reflect functional similarities. Gene Ontology (GO) enrichment assigned the AmNF-YC genes to 23 functional categories, indicating substantial functional diversification despite the presence of conserved protein motifs. Furthermore, based on cis-acting element analysis, we investigated the responses of AmNF-YC genes to methyl jasmonate (MeJA) treatment. Six AmNF-YC promoters contained MeJA-responsive elements, and NF-YC genes regulated by MeJA exhibited significantly upregulated expression following MeJA treatment. This study provides the first comprehensive identification and characterization of the NF-YC gene family in A. membranaceus, establishing a foundation for future research on their roles in biological processes and stress signaling pathways.