Enhancing antioxidant systems by preharvest treatments with methyl jasmonate and salicylic acid leads to maintain lemon quality during cold storage.

The effects of preharvest treatments with 0.1 mM methyl jasmonate (MeJA) and 0.5 mM salicylic acid (SA) on quality parameters of lemon fruit and their relationship with antioxidant systems, gene expression and bioactive compounds at harvest and during cold storage were evaluated. Results showed that total antioxidant activity, total phenolic content and the major individual phenolics (hesperidin and eriocitrin) were always higher in treated fruit than in controls. The activity of the antioxidant enzymes catalase, peroxidase and ascorbate peroxidase was also increased at harvest by SA and MeJA treatments, especially the last enzyme, for which the expression of its codifying gene was also enhanced. In addition, treated fruit had lower weight and firmness losses, respiration rate and production of ethylene than controls. Moreover, sugars and organic acids were maintained at higher concentration in flavedo and juice as a consequence of preharvest SA and MeJA treatments, showing an effect on maintaining fruit quality properties.