Effect of Salicylic Acid Dipping on Postharvest Diseases and Phenylpropanoid Pathway in Muskmelon Fruits

【Objective】The effects of salicylic acid(SA) dipping on postharvest disease resistance and phenylpropanoid pathway in muskmelon fruit was investigated in this paper.【Method】 Muskmelons(Cucumis melo L.cv.Yujinxiang) were dipped at 4 mmol·L-1 of SA for 10 min.The inhibition effect of SA dipping on the lesion diameter of fruits inoculated with Trichothecium roseum and natural incidence of melons were investigated during storage at room temperature.The key enzyme activities and substances accumulation of phenylpropanoid pathway in fruits were also detected.【Result】 SA significantly decreased the lesion diameter of fruits inoculated with T.roseum,and the natural incidence of fruits during storage at room temperature.The treatment increased the activity of phenylalanine ammonia-lyase(PAL),4-coumarate: CoA ligase(4CL) and cinnamate-4hydroxylase(C4H) in fruits.The activity of C4H and 4CL was 1.0 and 2.8 times higher in treated fruits than that in the control after 6 days of treatment,and PAL activity was 1.6 times of the control after 10 days of treatment.SA significantly enhanced the content of total phenolic and lignin.The content of lignin and total phenolic was 30.6% and 30.0% higher in treated fruits than that in the control after 4 and 10 days of treatment;however,no significant difference was found in flavanoid content between the treatment and the control.【Conclusion】Postharvest SA treatment could increase the resistance in melon fruits against postharvest diseases by inducing phenylpropanoid pathway.