Temperature gradient storage induced biochemical and molecular changes in mango (Mangifera indica L. cv. Alphonso) fruits

Mango fruit is severely affected by chilling injury during storage at low temperatures. The molecular and biochemical processes occurring in fruits during the course of chilling injury development are not yet completely understood. The current study was carried out using the fruits of mango cv. Alphonso. Fruits were exposed to two treatments comprising temperature gradient storage (TGS) and low-temperature (5 degrees C) storage for 10, 20 and 30 days and compared with the room-temperature ripened fruits (control). The generation of free radicals and the content of malondialdehyde (MDA), leakage of electrolytes (EL), fatty acids, chlorophyll and total carotenoids were significantly affected in 5 degrees C stored fruits compared to control and TGS. Significant increase was observed in free radical generation and antioxidant enzyme activities at 5 degrees C storage. Consequently, the peroxidation of lipids and protein carbonyls were also significantly higher in low-temperature stored fruits. Unsaturated fatty acids were markedly reduced during the first 20 days at 5 degrees C leading to severe membrane leakage compared to TGS. Gene expression of Fatty Acid Desaturase (FAD), Peroxidase (POD) and Glutathione Reductase (GR) correlated with the observed increase in the level of unsaturated fatty acids, indicating the roles of these enzymes in cold stress-induced membrane changes. Out study has shown that the TGS treatment significantly reduces chilling injury by increasing the unsaturated fatty acids and also by reducing the peroxidation of lipids and protein carbonyls when compared to storage at 5 degrees C.