Root-sourced H₂O₂ is essential for maintaining jasmonic acid and Na⁺/K⁺ homeostasis to delay leaf senescence during salt stress in Paspalum vaginatum

Improving salt tolerance and mitigating senescence in the presence of high salinity are crucial for sustaining agricultural productivity. Previous research has demonstrated that hydrogen peroxide (H₂O₂), specifically H₂O₂ derived from roots and mediated by the respiratory burst oxidase homolog (NADPH), plays a significant role in regulating ion and plant hormone homeostasis in glycophytic plants, such as Arabidopsis. However, the extent to which root-derived H₂O₂ fulfils similar functions in halophytic plants remains uncertain. Therefore, our study aimed to explore the potential contribution of root-sourced H₂O₂ in delaying leaf senescence induced by high salinity, utilizing seashore paspalum as a model halophytic plant. The application of the NADPH-oxidase inhibitor DPI, coupled with a series of leaf senescence analyses, we revealed that root-derived H₂O₂ significantly retards salt-induced leaf senescence. Furthermore, through the application of hormone analysis, lipidomics, ionomics, Non-invasive Micro-test Technology (NMT), and transcriptomics, we established that NADPH-dependent H₂O₂ induced by salt stress in the roots was indispensable for maintaining the balance of the aging hormone, jasmonic acid (JA), and sodium ion homeostasis within this halophytic plant. Finally, by utilizing AtrbohD Arabidopsis mutants and virus-induced gene silencing (VIGs) in Paspalum vaginatum, we demonstrated the pivotal role played by root-sourced H₂O₂ in upholding JA homeostasis and regulating JA-triggered leaf senescence in P. vaginatum. This study offers novel insights into the mechanisms that govern plant leaf senescence and its response to salinity-induced stress.