Distinct post-harvest deterioration pathways caused by light vs dark storage of fresh-cut lettuce packed in modified atmosphere.

Modified atmosphere packaging (MAP) combined with low temperatures is a proven method for maintaining the quality of fresh-cut lettuce (Lactuca sativa), particularly in relation to cut surface discoloration. However, even though fresh-cut products in retail environments can be influenced by even low levels of photosynthetic light, few studies have focused on the impact of light on MAP products. In this study, we found that constant low light illumination undermines the effectiveness of MAP for fresh-cut lettuce. This is associated with a slight temperature increase in the storage cabinet and photosynthetic gas exchange restoring normal atmospheric gas compositions, accelerating quality loss. These light-induced changes are correlated with transcriptional hallmarks of senescence. In contrast, even with extended storage beyond typical retail standards, these hallmarks were absent in darkness. Instead, there were transcriptional and metabolite profile signatures related to low oxygen and oxylipin metabolism. Furthermore, the phenylpropanoid pathway, which is central to cut-surface discoloration, appeared to be dynamically responsive to lighting and increasing storage time throughout the storage period. In conclusion, this study reveals temporal transcriptomic and metabolomic responses that are highly conditioned by lighting during MAP-storage of fresh-cut lettuce.