Genome-wide identification and expression analysis of WRKY transcription factor family members in seashore paspalum under salt stress

Although WRKY transcription factors (TFs) are established key regulators of plant stress responses, their contributions to highly salt-tolerant halophytes remain poorly understood. This study presents the first comprehensive genome-wide characterization of the WRKY gene family in the exceptionally salt-tolerant halophyte, seashore paspalum (<italic>Paspalum vaginatum</italic>). Using HMM profile searches and conserved domain analysis, 126 nonredundant PvWRKY sequences were identified. These were subsequently classified phylogenetically by comparison to Arabidopsis orthologs into established groups: Group I (n = 22), Group II (n = 58, subgroups IIa-IIe), and Group III (n = 46). Protein characterization revealed unstable hydrophilic PvWRKYs predominantly localized to the nucleus (84.92%), consistent with their transcriptional regulatory roles. Promoter <italic>cis</italic>-element analysis identified enrichment in stress-responsive motifs, with ABA-responsive elements (ABRE; present in 116 genes) and MeJA-responsive elements (detected in 115 genes), highlighting hormonal integration in salt adaptation. Intraspecific collinearity and tandem duplication events on chromosomes 2, 3, 5, and 9 suggested evolutionary expansion via gene duplication. Transcriptome and quantitative reverse transcription (qRT-PCR) analyses revealed spatiotemporal expression dynamics under salt stress: <italic>PvWRKY105/117/126</italic> exhibited root-specific upregulation during prolonged stress, whereas <italic>PvWRKY84/58/90</italic> were leaf-predominant responders. Functional annotation (GO) linked <italic>PvWRKY</italic>s to root development (GO:0048364), oxidative stress response, and MAPK signaling, with protein-protein interaction (PPI) networks identifying <italic>PvWRKY52</italic> as a central hub interacting with key stress regulators (MKS1, MPK3/MPK4). Additionally, <italic>PvWRKY123</italic> showed ABA signaling synergism via ABI4/ABI5 interactions, while <italic>PvWRKY86</italic> was associated with SUMOylation-mediated regulation through BZIP8 and SUMO1. This genome-wide exploration of the WRKY family in seashore paspalum emphasizes its regulatory potential in salt adaptation and offers a foundation for future functional analyses.