Postharvest application of the strigolactone analog GR24 enhances antioxidant capacity and delays senescence in cut roses (Rosa hybrida) with Transcriptomic evidence for the involvement of phenylpropanoid biosynthesis genes.

The commercial value of cut roses is severely constrained by their short vase life, which results from rapid postharvest senescence. Although strigolactones (SLs) are known to regulate plant stress responses, their role in preserving cut flowers remains largely unexplored. In this study, we integrated physiological assessments and transcriptomic sequencing to investigate whether exogenous application of the synthetic SL analog GR24 could delay senescence in cut roses (Rosa hybrida). Treatment with 1 μM GR24 significantly extended vase life by 4 days compared with the control. Physiologically, GR24 mitigated water loss, as evidenced by maintained higher relative fresh weight and floral diameter. It also alleviated membrane lipid peroxidation by reducing relative electrolyte leakage and malondialdehyde accumulation, while increasing soluble protein and sugar contents, as well as catalase and peroxidase activities. Orthogonal Partial Least Squares-Discriminant Analysis and Variable Importance in Projection scores identified the mitigation of membrane damage and maintenance of antioxidant capacity as key physiological factors underlying the preservative effect of GR24. Transcriptomic analysis revealed 47 differentially expressed genes (DEGs) in response to GR24, with KEGG enrichment highlighting the phenylpropanoid biosynthesis pathway as a major regulatory target. The significant upregulation of key enzyme genes (PAL1, HHT1, POD-4, LAC5, and HCT) suggests that GR24 reinforces physical defenses, potentially through transcriptional activation of phenolic compound biosynthesis-related genes. Promoter analysis revealed putative binding motifs for MYB46, NAC43, and DOF3.4 in the upstream regions of HCT, PAL1, LAC5, and HHT1, and their expression patterns were correlated with these genes, suggesting that they are candidate regulators of phenylpropanoid biosynthesis. Collectively, these findings demonstrate that GR24 delays postharvest senescence by alleviating water imbalance, enhancing antioxidant capacity, with transcriptomic evidence suggesting the involvement of phenylpropanoid biosynthesis-related genes and other critical genes. This work provides novel molecular insights into the application of SLs for cut flower preservation.