The alleviation of methyl jasmonate on loss of aroma lactones correlated with ethylene biosynthesis in peaches.

Peaches are vulnerable to cold temperature, showing the symptoms of chilling injury (CI). The occurrence of CI results in irreversible aroma loss, especially 'peach-like' lactones loss during cold storage and subsequent shelf life. Methyl jasmonate (MeJA) treatment is effective in alleviating CI symptoms in peach fruit; however, its effect on peach aroma volatiles is still unknown. To explore the effect and mechanism of MeJA treatment on aroma loss of peaches, fruit was treated with 10 µmol/L MeJA, then stored at 4 °C for 3 weeks, and subsequently transferred to 20 °C to simulate shelf life for 3 days. Here, the ability of MeJA to regulate aroma lactones of 'Xiahui 6' peaches was investigated, and the expression of genes responsible for ethylene and lactones biosynthesis was considered. MeJA treatment significantly reduced internal browning index, increased ethylene production, and promoted the emission of aroma-related lactones in peaches during shelf life at room temperature. In addition, MeJA also elevated the expression of PpSAMS, PpACS3, PpACS4, PpACO, and PpACX3 during or after cold storage. These results suggested that MeJA treatment could enhance chilling tolerance in peaches and induce the recovery of ethylene and aroma lactones, which is closely related to ethylene biosynthesis as revealed by upregulated genes expression of PpSAMS, PpACS3/4, and PpACO. PRACTICAL APPLICATION: This research provides theoretical basis for the application of methyl jasmonate in fruit preservation and the basis for molecular breeding to cultivate aroma-abundant peach fruits.