Genome-Wide Identification and Expression Analysis of NAC Gene Family Members in Seashore Paspalum Under Salt Stress

The <i>NAC</i> gene family plays a crucial role in plant growth, development, and responses to biotic and abiotic stresses. <i>Paspalum Vaginatum</i>, a warm-season turfgrass with exceptional salt tolerance, can be irrigated with seawater. However, the <i>NAC</i> gene family in seashore paspalum remains poorly understood. In this study, genome-wide screening and identification were conducted based on the <i>NAC</i> (<i>NAM</i>) domain hidden Markov model in seashore paspalum, resulting in the identification of 168 <i>PvNAC</i> genes. A phylogenetic tree was constructed, and the genes were classified into 18 groups according to their topological structure. The physicochemical properties of the <i>PvNAC</i> gene family proteins, their conserved motifs and structural domains, cis-acting elements, intraspecific collinearity analysis, GO annotation analysis, and protein-protein interaction networks were analyzed. The results indicated that the majority of PvNAC proteins are hydrophilic and predominantly localized in the nucleus. The promoter regions of <i>PvNACs</i> are primarily enriched with light-responsive elements, <i>ABRE</i> motifs, <i>MYB</i> motifs, and others. Intraspecific collinearity analysis suggests that <i>PvNACs</i> may have experienced a large-scale gene duplication event. GO annotation indicated that <i>PvNAC</i> genes were essential for transcriptional regulation, organ development, and responses to environmental stimuli. Furthermore, the protein interaction network predicted that <i>PvNAC73</i> interacts with proteins such as <i>BZIP8</i> and <i>DREB2A</i> to form a major regulatory hub. The transcriptomic analysis investigates the expression patterns of <i>NAC</i> genes in both leaves and roots under varying durations of salt stress. The expression levels of 8 <i>PvNACs</i> in roots and leaves under salt stress were examined and increased to varying degrees under salt stress. The qRT-PCR results demonstrated that the expression levels of the selected genes were consistent with the FPKM value trends observed in the RNA-seq data. This study established a theoretical basis for understanding the molecular functions and regulatory mechanisms of the <i>NAC</i> gene family in seashore paspalum under salt stress.