iTRAQ proteomics reveals changes in the lettuce (Lactuca sativa L. Grand Rapid) proteome related to colour and senescence under modified atmosphere packaging

BACKGROUND This study used the isobaric tags for relative and absolute quantitation (iTRAQ) technique to determine the effects of active modified atmosphere packaging (MAP) on the modulation of lettuce (Lactuca sativa L. Grand Rapid) colour and senescence. Lettuces, treated or not treated (control) with MAP, were placed in a refrigerator (4 degrees C, 90-95% relative humidity) for analysis at 3-day intervals until the ninth day. RESULTS MAP treatment could suppress weight loss, loss of green colour and brittleness, and browning of lettuce; at the same time, MAP preserved the green colour of lettuce by inhibiting chlorophyll degradation and chloroplast disruption, and delayed lettuce senescence by inhibiting malondialdehyde (MDA) generation and increasing antioxidant enzyme activity. In total, 285 differentially abundant proteins (144 upregulated proteins and 141 downregulated proteins) were identified in MAP-treated and non-treated lettuce. Further analysis revealed that MAP regulated the expression of proteins involved in photosynthesis (e.g. pheophorbide a oxygenase, PaO; porphobilinogen deaminase, PBGD), and thus preserved lettuce colour. The iTRAQ analysis also showed that MAP regulated the expression of antioxidant enzymes and reduced the accumulation of reactive oxygen species, and thus delayed lettuce senescence. CONCLUSION MAP can maintain vegetable quality by inhibiting chlorophyll degradation, delaying vegetable senescence. (c) 2018 Society of Chemical Industry