Possible Mechanisms of Salicylic Acid Effects for Alleviation of Postharvest Chilling Injury on Tomato Fruit

Tomato fruit harvested at mature green stage and treated with salicylic acid at different concentration (0، 1 and 2 mM) and analyzed for chilling injury، electrolyte leakage، malondialdehyde، proline and total phenol contents and phospholipase D، lipoxygenase and phenylalanine ammonia-lyase activities during cold storage. Phospholipase D and lipoxygenase activities were significantly reduced by salicylic acid treatment. Compared with the control fruit، salicylic acid treatment alleviated chilling injury، reduced electrolyte leakage، malondialdehyde content and increased proline content. Salicylic acid application had no significant effect on total phenol content but phenylalanine ammonia-lyase activity was significantly reduced in treated fruits. Our result suggest that the reduce activity of PLD and LOX، by salicylic acid may be a chilling tolerance strategy in tomato fruit. Inhibition of PLD and LOX activity during low temperature storage could ameliorate chilling injury and oxidation damage and enhance membrane integrity in tomato fruit.