Methyl jasmonate induces resistance against Penicillium citrinum in Chinese bayberry by priming of defense responses

• 10 μmol L−1 MeJA significantly inhibited the Penicillium citrinum infection and natural decay in Chinese bayberries during the storage at 1 °C.
• The MeJA treatment up-regulated the H2O2 burst, enhanced translation levels of defense-related proteins and contents of antimicrobial compounds.
• The MeJA treatment induced disease resistance against P. citrinum by priming of defense responses.

Methyl jasmonate (MeJA) can act as an activator of defense responses in plants against pathogenic infection. However, the mechanisms involved in the postharvest induction of resistance by MeJA in fruit are largely unknown. Thus, we investigated the effect of a postharvest MeJA treatment on disease resistance against Penicillium citrinum infection in Chinese bayberries and the possible mechanisms. The results indicated that treatment with 10 μmol L−1 of MeJA significantly inhibited green mould rot caused by P. citrinum, with the decay incidence being 66.2% lower than that of the control fruit after storage at 1 °C for 8 d. Moreover, it is clear that MeJA triggers a priming mechanism in Chinese bayberries, since only the MeJA-treated fruit showed an enhanced capacity to augment defense responses upon challenge with the pathogen. These augmented responses included an H2O2 burst, enhanced protein levels of phenylalanine ammonia-lyase and chitinase, and accumulation of phenolic compounds, lignin and phytoalexin. Therefore, our results suggest that a postharvest MeJA treatment induces disease resistance against P. citrinum in Chinese bayberries by priming of defense responses.