n -Propyl dihydrojasmonates influence ethylene signal transduction in infected apple fruit by Botrytis cinerea

The effects of the jasmonic acid derivative n-propyl dihydrojasmonate (PDJ) on ethylene signal transduction and endogenous jasmonic acid (JA) in apples infected with Botrytis cinerea (gray mold) were investigated. Apples were dipped into 400 mu M PDJ solution and then inoculated with B. cinerea. The fruit were stored at 25 degrees C and 95% relative humidity for 16 days after PDJ treatment. The inoculation without PDJ application (PDJ(-) Ino(+)) showed larger B. cinerea lesion diameters compared to the PDJ application with inoculation (PDJ(-) Ino(+)) and the untreated controls. In contrast, the PDJ(-) Ino(+) group showed a higher ethylene production rate, higher 1-aminocyclo-propane-1-carboxylic acid (ACC) concentration, and greater expressions of ethylene-related genes [MdACS1 (ACC synthase), MdACO1 (ACC oxidase), MdETR1 (Ethylene receptor 1), MdERS1 (Ethylene response sensor 1), and MdCTR1 (Constitutive triple response 1)], and endogenous JA, MdAOS1 (Allene oxide synthase 1) gene. However, the abscisic acid concentrations were decreased in the PDJ(-) Ino(+) group. The results suggest that PDJ application induces ethylene production through ethylene-related genes and endogenous JA, resulting in B. cinerea infection inhibition.