Comprehensive Genome-Wide Analysis and Expression Profiling of Pathogenesis-Related Protein 1 (PR-1) Genes in Salvia miltiorrhiza

Abstract

The pathogenesis-related 1 (PR-1) gene family is essential for plant defense and stress response. In this study, 11 SmPR-1 genes were identified in Salvia miltiorrhiza through comprehensive genomic analysis, all of which encoded proteins with conserved CAP (cysteine-rich secretory protein, antigen 5, and pathogenesis-related 1) domains and signal peptides. Phylogenetic analysis categorized these genes into five evolutionary clusters, reflecting their evolutionary divergence. Chromosomal localization analysis revealed that the SmPR-1 gene family is distributed across three chromosomes: Chr1 contains six genes, Chr6 contains three, and Chr8 contains one. Intraspecific collinearity analysis indicated segmental duplications of SmPR-1-5 and SmPR-1-11 on Chr1. Interspecific collinearity analysis showed that five SmPR-1 genes are collinear with both Arabidopsis thaliana and Scutellaria baicalensis, with SmPR-1-1 also exhibiting collinearity with Oryza sativa and Zea mays. Tissue-specific expression profiling indicated high expression levels in the flowers and stems, indicating their roles in various developmental processes. Differential expression patterns under hormonal and biotic stress revealed that SmPR-1-5 was particularly responsive to brassinosteroid (BR) treatment. Subcellular localization analysis indicated that SmPR-1-5 was present in both the cytoplasm and nucleus, suggesting its involvement in intracellular signaling. Additionally, CMV infection triggered a time-dependent expression pattern, activating specific genes during the early and late infection stages. These findings provide valuable insights into the functional roles of SmPR-1 genes in stress responses and immunity, laying the groundwork for breeding disease-resistant S. miltiorrhiza varieties. Future research should explore the regulatory mechanisms and interactions of SmPR-1 genes with other defense pathways to fully understand their contribution to plant resistance.