Genome-wide characterization of WRKYs and function of SpWRKY40 and SpWRKY50 in Sesuvium portulacastrum

WRKYs represent a large family of plant transcription factors characterized by a highly conserved WRKY domain. WRKY transcription factors are important for plant growth, development, and responses to environmental stresses. However, this family has not been previously identified in Sesuvium portulacastrum. Here, we comprehensively identified 68 SpWRKYs from the genome of S. portulacastrum by phylogenetic relationships, chromosomal localization, collinearity analysis, gene structure, duplication events, and evolutionary pressure based on nonsynonymous substitution rate/synonymous substitution rate ratios. Promoter analysis revealed the presence of multiple cis-elements associated with abiotic stress signaling, developmental regulation, phytohormone responses, light responsiveness, and tissue-specific expression. We also characterized the physicochemical and structural properties of the SpWRKY-encoded proteins, including protein property of primary structure, secondary structures, and predicted three-dimensional models, subcellular localization, conserved motifs, and conserved domains. Furthermore, transcriptome profiling under cadmium, copper, and salt stress conditions demonstrated differential expression patterns of SpWRKYs. Among them, SpWRKY40 and SpWRKY51showed significant indued under cadmium treatment and were further validated by quantitative real-time PCR. Subcellular localization and yeast one-hybrid assays both supporting SpWRKY40 and SpWRKY51 play as transcription factors. Our study provides a detailed overview of the SpWRKY family and their potential involvement in environment tolerance. The findings offer valuable candidate genes for future applications in improving stress tolerance in S. portulacastrum and related crop species.