Comparison of antioxidant levels and cell membrane composition during fruit development in two plum cultivars (Prunus salicina Lindl.) differing in chilling resistance

It is known that chilling resistant cultivars are able to modify their membrane composition and/or antioxidant profile under low-temperature storage conditions unlike chilling susceptible cultivars. Knowledge of the differences in membrane composition and antioxidant levels during plum fruit development in both chilling resistant and -susceptible plum cultivars could help to establish or improve current orchard and/or postharvest handling practices to alleviate the occurrence of chilling injury in susceptible cultivars. The aim of this study was to determine if apparent differences in cell membrane composition and antioxidant levels between chilling susceptible (in this study 'Sapphire') and chilling resistant (in this study 'Angeleno') plum cultivars already exist during fruit development. Regarding antioxidants, 'Sapphire' accumulated higher levels of glutathione, while 'Angeleno' accumulated higher levels of ascorbic acid. The driving factor for chilling susceptibility in 'Sapphire' plums seems to be the cultivar's ability to accumulate higher levels of linoleic acid compared to oleic acid. Linoleic acid (a polyunsaturated fatty acid) is more susceptible to lipid peroxidation than oleic acid (a monounsaturated fatty acid). 'Angeleno' accumulated higher levels of oleic acid, compared to linoleic acid, which probably renders the cultivar more tolerant to low temperature storage. The difference in the antioxidants and phospholipid fatty acids that were accumulated in the two cultivars is related to the time the fruit spend on the tree during fruit development. 'Sapphire' is an early season cultivar which, therefore, experiences lower average daily temperatures during fruit development. Glutathione and linoleic acid accumulate under lower temperatures. 'Angeleno' is a late season cultivar, experiencing higher average daily temperatures during the latter half of its fruit development period. Higher temperatures favour the accumulation of ascorbic acid and oleic acid.