Chilling injury in mango fruit in relation to biosynthesis of free polyamines

Abstract

SummaryMature green mango (Mangifera indica L. ‘Kensington Pride’) fruit were stored at 0, 5, 10, 15 and 20°C for 1, 3, 7, 14, 21 and 28 d during 1999 to induce different levels of chilling injury (CI) and to investigate its relationship with endogenous polyamines during storage. In second experiment during 2000, fruit were stored at 5 and 15°C for two weeks and allowed to ripen at 22±1°C to elucidate the relationship between endogenous free polyamines and CI during ripening. CI index on fruit increased as the storage temperature was decreased from 10 to 0°C and the storage period was prolonged from 1 to 28 d. CI symptoms progressed during the ripening period in fruit stored at 5°C for two weeks. Total free polyamines in the skin and pulp were higher in the chill injured fruit as compared with the non-chill injured fruit during storage and ripening except on day 4 of the ripening period. Accumulation of putrescine and depletion of spermidine and spermine in the skin and pulp of the chill injured fruit was recorded during the storage and ripening periods. In third experiment during 2000, amongst different concentrations of three polyamines tested, exogenous application of spermine (0.50 mM) was most effective in reducing CI. In conclusion, putrescine accumulation did not inhibit CI in mango fruit – rather the chilling stress promoted its accumulation at the early stages of ripening. The depletion of endogenous spermidine and spermine with CI and the reduction of CI with pre-storage application of these polyamines indicate that CI development in mango fruit seems to be associated with the biosynthesis of polyamines.