Transcriptomic Analysis of the Mechanisms Underlying Delayed Quality Deterioration in Fresh-Cut Asparagus Lettuce Using Ascorbic Acid and L-Cysteine in a Sodium Carboxymethyl Cellulose Coating

Browning and green loss are two typical characteristics of quality deterioration in fresh-cut asparagus lettuce (Lactuca sativa var. angustata). In the present study, the mechanism underlying the delay in quality deterioration of fresh-cut asparagus lettuce by the solution was elucidated through transcriptomic analysis. Fresh-cut asparagus lettuce was immersed in a solution containing 0.67% sodium carboxymethyl cellulose (CMC-Na), 0.85% L-cysteine (L-Cys), 0.38% ascorbic acid (AsA), and the distilled water (control) for 10 min, respectively. Both treated and control samples were stored in the dark at 4°C with 80%–90% relative humidity for eight days. The results showed that treatment with the solution retarded the cut surface browning and green color loss and extended the shelf life of fresh-cut asparagus lettuce. In comparison to a control group, the treatment effectively attenuated the upregulation of the LsACO3 and LsACS1 genes; it downregulated the expression of the phospholipase-related genes LsNPC6, LsPLC2, and At2g42690. Conversely, there was substantial upregulation of gene expression related to L. sativa calmodulin-like proteins and L. sativa calcium-dependent protein kinases, along with activation of the mitogen-activated protein kinase (MAPK) signaling pathway and significant upregulation of genes associated with the L. sativa jasmonic acid biosynthesis pathway involved in the defense response. In conclusion, our findings indicated that treatment with the solution effectively delays the deterioration of fresh-cut asparagus lettuce during storage by inhibiting endogenous ethylene synthesis, mitigating reactive oxygen damage, and enhancing disease resistance, thereby providing superior preservation of its color and texture. The results provide an alternative method for delaying color deterioration of fresh-cut produce.