Role of epicuticular wax involved in quality maintenance of table grapes: Evidence from transcriptomic data

Epicuticular wax is the natural protective coating of fruit which is vulnerable to insect, microbe, pollutant, or scrape incidence. Herein, the epicuticular wax of table grapes was removed to mimic the natural wax loss/ damage, and the quality attributes of fruit were investigated. Results demonstrated wax removal triggered fruit weight loss, softening and browning during storage. Transcriptomic analysis showed 623 up-regulated and 573 down-regulated genes, focusing on polyphenols biosynthesis, cell wall metabolism, photosynthesis, and so forth. Up-regulated expression levels of genes involved in chlorophyll degradation contributed to visible browning; and the facilitated cell wall collapse observed by transmission electron microscope (TEM) and doubled pectinesterase expression were illustrated in fruit softening. Taken together, our findings provide novel insights into the role of epicuticular wax as the natural coating in quality maintenance of table grapes from the transcriptomic evidence.

Automated summary

The removal of epicuticular wax from table grapes resulted in weight loss, softening, and browning during storage. Transcriptomic analysis revealed the up-regulation and down-regulation of numerous genes, particularly those involved in polyphenols biosynthesis, cell wall metabolism, and photosynthesis. The up-regulated expression of chlorophyll degradation genes contributed to visible browning, while the observed cell wall collapse and increased pectinesterase expression explained fruit softening. These findings provide novel insights into the role of epicuticular wax in maintaining the quality of table grapes, supported by transcriptomic evidence.