| The effects of low molecular chitosan (LMC), modified atmosphere packing (MAP) and LMC+MAP on cherry tomato fruit were compared at levels of enzymatic activity and proteomics, to discuss the changes of ripening cherry tomato fruit treated by these treatments.Enzymatic activity:the increased activities of ascorbate peroxidase (APX), pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH) were determined in LMC treatment. The increased activities of APX and PDC were determined in MAP treatment. The increased activities of superoxide dismutase (SOD), APX and ADH were determined in LMC+MAP treatment. The results indicated that these treatment could enhance the antioxidant ability of cherry tomato fruit, while there might be the accumulation of acetaldehyde and ethanol during storage.Proteomics:After two-dimensional electrophoresis and MALDI-TOF/TOF, the results showed that there were 42 differently expressed spots (P<0.05), including the catalogue of stress response and defense (38.10%), energy (21.43%), metabolism (7.14%), ripening and senescence (4.76%), detoxification (4.76%), cell fate (7.14%) and unclassified (16.67%). Considering the function and expression change of proteins, the results suggested that LMC treatment could the induce glutathione reductase (GR), flavonol synthase and heat shock proteins (HSP) for stress resistance, and enhance the expression of proteins involved in glycolysis and fermentation pathways for energy metabolism, while suppress the expression of 1-aminocyclopropane-l-carboxylate oxidase (ACOs) and pectin methyl esterase (PME) for less ethylene metabolism.After two-dimensional electrophoresis and MALDI-TOF/TOF, the results showed that there were 39 differently expressed spots (P<0.05), including the catalogue of stress response and defense (30.77%), energy (25.64%), cell fate (15.38%), ripening and senescence (5.13%), detoxification (5.13%) and others (17.95%). Considering the function and expression change of proteins, the results suggested that MAP treatment could induce glutathione s-transferase (GST) and inhibit salicylic acid-binding protein 2 (SABP 2) for stress resistance, while reduce the expression of proteins involved in glycolysis and fermentation pathways for less energy metabolism, and suppress the expression of ACOs for less ethylene metabolism.After two-dimensional electrophoresis and MALDI-TOF/TOF, the results showed that there were 50 differently expressed spots (P<0.05), including the catalogue of stress response and defense (36.00%), energy (24.00%), cell fate (12.00%), metabolism (6.00%), ripening and senescence (4.00%), detoxification (4.00%) and unclassified (14.00%). Considering the function and expression change of proteins, the results suggested that MAP treatment could induce GR, GST and inhibit SABP 2 for stress resistance, while reduce the expression of proteins involved in glycolysis and fermentation pathways for less energy metabolism, and suppress the expression of ACOs and PME for less ethylene metabolism.In conclusion, these treatment could enhance the expression of antioxidant proteins and heat shock proteins to increase stress resistance, while suppress the expression of proteins involved in the ethylene biosynthesis to inhibit the ethylene metabolism, to delay the ripening and senescence of cherry tomato fruit. |
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