Influence of preharvest and postharvest methyl jasmonate treatments on flavonoid content and metabolomic enzymes in red raspberry

The effect of preharvest and postharvest treatments with methyl jasmonate on the concentrations of myricetin, ellagic acid and quercetin in red raspberry was investigated. Different raspberry varieties and different MJ concentrations were included in the study. The preharvest MJ application to raspberry plants resulted in a significant increase of the flavonoids in all varieties. Increases from 90.32 to 336.95 μg/g of myricetin, from 103.15 to 218.91 μg/g of ellagic acid and from 65.22 to 163.15 μg/g of quercetin were obtained in Glen Lyon variety after pre-harvest treatment with 0.1 mM MJ. Postharvest MJ treatment did not lead to such a significant increase in the concentrations but enabled natural decline during storage to be avoided. Contents of myricetin, ellagic acid and quercetin were maintained. Concentrations in postharvest MJ treated raspberries were constant between 60 and 100 μg/g. Enzyme studies reflected increase in PAL activity after preharvest MJ treatment. No MJ promoting effect and even an inhibitory effect was however observed in FHT and FLS enzymes, respectively. The results found in the present work help get an insight into the mechanisms of MJ action in phenylpropanoid metabolism in raspberries. Preharvest MJ treatment of raspberries can be useful for obtaining fruit with enhanced healthy promoting properties.