Salinity stress causes serious damage to crops worldwide, limiting plant production. However, the metabolic and molecular mechanisms underlying the response to salt stress in rose (Rosa spp.) remain poorly studied. We therefore performed a multi-omics investigation of Rosa hybrida cv. Jardin de Granville (JDG) and Rosa damascena Mill. (DMS) under salt stress to determine the mechanisms underlying rose adaptability to salinity stress. Salt treatment of both JDG and DMS led to the buildup of reactive oxygen species (H₂O₂). Palisade tissue was more severely damaged in DMS than in JDG, while the relative electrolyte permeability was lower and the soluble protein content was higher in JDG than in DMS. Metabolome profiling revealed significant alterations in phenolic acid, lipids, and flavonoid metabolite levels in JDG and DMS under salt stress. Proteome analysis identified enrichment of flavone and flavonol pathways in JDG under salt stress. RNA sequencing showed that salt stress influenced primary metabolism in DMS, whereas it substantially affected secondary metabolism in JDG. Integrating these datasets revealed that the phenylpropane pathway, especially the flavonoid pathway, is strongly enhanced in rose under salt stress. Consistent with this, weighted gene coexpression network analysis (WGCNA) identified the key regulatory gene chalcone synthase 1 (CHS1), which is important in the phenylpropane pathway. Moreover, luciferase assays indicated that the bHLH74 transcription factor binds to the CHS1 promoter to block its transcription. These results clarify the role of the phenylpropane pathway, especially flavonoid and flavonol metabolism, in the response to salt stress in rose.

AGAMOUS-LIKE 24 (AGL24) is a key gene regulating floral transition, but its involvement in flower organ identity remains largely unknown. In this study, we found that RhAGL24 is strongly related to petal and stamen development in rose. Its expression increases rapidly at the petal primordium development stage and maintains a high level until the complete differentiation stage. RhAGL24 silencing increases the number of malformed petals and decreases the number of stamens, indicating that this gene affects stamen petaloidy. RhAG (AGAMOUS), a class C gene associated with petal and stamen development, is downregulated in RhAGL24-silenced plants. Moreover, we found that RhAGL24 could directly bind to the promoter region of RhARF18 (AUXIN RESPONSE FACTORS 18), a regulator of RhAG. Our results suggested that RhAGL24-RhARF18 module regulates stamen petaloidy in rose and provide new insights into the function of AGL24 for plants.