Genome-wide identification and expression analysis <i>Pvrboh</i> genes reveal their potential roles in salt tolerance and calcium signaling

Salinity stress is a major environmental factor that limits plant growth and productivity. Understanding the mechanisms of plant salt tolerance is crucial for improving crop yields in saline soils. The Respiratory Burst Oxidase Homologs (Rboh) gene family triggers the production of reactive oxygen species, which act as a signaling molecule to regulate plant tolerance and development under saline conditions. However, a comprehensive analysis of the Rboh gene family in halophytic plants is largely unexplored. In this study, we characterized members of the Rboh gene family in Paspalum vaginatum, a typical halophyte. Evolutionary analysis revealed numerical differences in Pvrboh genes compared to those related species. Additionally, cis-acting elements related to plant hormones, light response, and plant development were identified in Pvrboh promoters. All Pvrboh genes were found to be membrane-localized and upregulated under high salinity, contributing to either root-sourced or leaf-sourced H2O2 production. Gene structural analysis and Ca2+ inhibitor experiments further indicated that Pvrboh4 and Pvrboh5 were closely associated with Ca2+ signaling, whereas Pvrboh6 did not exhibit such an association. Split-luciferase assay in N. benthamiana showed that PvRBOH5 strongly interacted with AtCPK5. Furthermore, a gene regulatory network analysis revealed multiple transcription factors from 32 distinct families that may regulate Pvrboh5 expression. These findings provide new insights into the role of Pvrboh genes in enhancing plant salt tolerance, offering potential targets for improving stress resilience in crops.