Nitric Oxide and Hydrogen Peroxide Are Involved in Methyl Jasmonate-Regulated Response against in Postharvest Blueberries.

The involvement and the relationship between nitric oxide (NO) and hydrogen peroxide (HO) in methyl jasmonate (MeJA)-induced immune responses in blueberries against was explored using diphenylene iodonium (DPI, NADPH oxidase inhibitor) and 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO, NO scavenger). MeJA induced NO and HO burst and enhanced the resistance of blueberries by elevating defense-related enzymes and the phenylpropanoid pathway. However, the above impacts stimulated by MeJA were weakened by DPI and destroyed by cPTIO. Furthermore, cPTIO abolished the increment in HO by regulating the activities of NADPH oxidase, superoxide dismutase, catalase, and ascorbate peroxidase, whereas DPI weakened the increase in HO but barely affected the generation of NO and the activity of nitric oxide synthase elevated by MeJA. These results indicated that NO and HO were involved in the MeJA-induced resistance in blueberries, and NO worked upstream of HO in this process.