Effects of methyl jasmonate(MeJA) on postharvest decay,phenylpropanoid metabolism and antioxidant activity in strawberry fruit

The effects of methyl jasmonate(MeJA) on postharvest decay,phenylpropnaoid metabolism and antioxidant activity in harvested strawberry fruit cv.Feng Xiang were investigated.The fruit were pretreated with 10 μ mol/L MeJA at 20 °C for 6 h and then stored at 1 °C for 12 days.The fruit decay incidence,activities of phenylpropanoid-related enzymes including phenylalanine ammonia-lyase(PAL),cinnamate-4-hydroxylase(C4H),4-coumarate/coenzyme A ligase(4-CL) and dihydroflavonol 4-reductase(DFR) as well as total phenolics,anthocyanins and individual phenolic compounds contents were measured at 2-day intervals during storage.Meanwhile,the effects on scavenging capacity against 1,1-diphenyl-2-picrylhydrazyl(DPPH) and reducing power associated with the MeJA treatment were also determined.The results showed MeJA significantly reduced fruit decay incidence,and enhanced the activities of PAL,4-CL,C4H and DFR,thus effectively preventing the decrease in total phenolics and anthocyanins contents and induced the biosynthesis of individual phenolic and anthocyanin compounds.Furthermore,these MeJA-treated fruits also maintained significantly higher antioxidant activity as measured by scavenging capacity against DPPH radical and reducing power test than the controls.These results suggest that ethanol vapor treatment may be a promising method to control postharvest decay and maintain quality in strawberry during storage.