Polyamines Conjugated to Plasma Membrane Were Involved in Melatonin-mediated Resistance of Apple (Malus pumila Mill.) Fruit to Chilling Stress
2022
Dong, Q. Y. | Lai, Y. | Hua, C. M. | Liu, H. P. | Kurtenbach, R.
It has been well documented that polyamine is associated closely with environmental stresses and melatonin pretreatment enhances the resistance of fruit to cold stress. However, mechanism underlining melatonin-mediated chilling resistance remains to be explored. Therefore, in the research, flesh browning degree, relative plasma membrane permeability, malondialdehyde and protein sulfhydryl content in plasma membrane were used to assess the resistance of apple fruit to chilling stress. The polyamine conjugated to plasma membrane of melatonin-pretreated apple (Malus pumila Mill.) fruit flesh cell was elucidated under chilling stress. The results showed that melatonin pretreatment led to obvious increases in the contents of conjugated non-covalently spermidine and spermine, and conjugated covalently putrescine and spermine in plasma membrane of apple fruit under chilling stress, compared with the apple fruit without melatonin pretreatment. Methylglyoxyl-bis (guanylhydrazone) pretreatment could inhibit the melatonin-induced increases of conjugated non-covalently spermidine and spermine by inhibiting the activity of S-adenosylmethionine decarboxylase and free spermidine and spermine contents in flesh, coupled with the decrease in chilling resistance. Similarly, phenanthrolin pretreatment could inhibit the melatonin-induced increases in putrescine and spermidine covalently conjugated to plasma membrane by inhibiting transglutaminase activity in flesh, simultaneously aggravating chilling damage. From the results collectively, it should be suggested the melatonin pretreatment could enhance chilling resistance by increasing non-covalently conjugated spermidine and spermine, and covalently conjugated putrescine and spermine in plasma membrane of apple fruit.
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