A study on JA- and BTH-induced resistance of Rosa rugosa ‘Plena’ to powdery mildew (Sphaerotheca pannosa)

Different concentrations of jasmonic acid (JA) and benzothiadiazole (BTH) were sprayed on 2-year-old Rosa rugosa ‘Plena’ seedlings. The induced resistance of JA and BTH to Sphaerotheca pannosa (Wallr.) and the changes of their related physiological indices were investigated. Results showed that JA and BTH treatments had inhibitory impacts on S. pannosa infection. The optimal concentration of JA and BTH was 0.5 mmol/L for the disease-resistance induction of the leaves, its inductive effect was up to 66.36% for BTH and 54.49% for JA. Our results confirmed that exogenous JA and BTH significantly improved R. rugose ‘Plena’ resistance to S. pannosa . When treated with JA and BTH, activities of the three defense enzymes (POD, PPO, and PAL) increased significantly. Contents of total phenolics, flavonoids, and lignin also increased significantly. It is inferred from these results that exogenous JA and BTH could improve the resistance of R. rugose ‘Plena’ to S. pannosa through enhancing activities of the defensive enzymes and accumulation of secondary metabolites in the leaves.