Transcriptomic and Metabolomic Basis of Short- and Long-Term Post-Harvest UV-C Application in Regulating Grape Berry Quality Development

In this study, ultraviolet-C (UV-C) was utilized to improve the quality of post-harvest grape berries, and the transcriptomic and metabolomic basis of this improvement was elucidated. Berries of the red grape variety 'Zicui' and the white variety 'Xiangfei' were chosen to evaluate the effect of short- and long-term UV-C irradiation. Post-harvest UV-C application promoted malondialdehyde (MDA) and proline accumulation, and reduced the soluble solid content in berries. Both the variety and duration of irradiation could modulate the transcriptomic and metabolomic responses of berries to UV-C. Compared with the control, the differentially expressed genes (DEGs) identified under UV-C treatment were enriched in pathways related to metabolite accumulation, hormone biosynthesis and signal transduction, and reactive oxygen species (ROS) homeostasis. Flavonoid biosynthesis and biosynthesis of other secondary metabolites were the shared pathways enriched with differential metabolites. After long-term UV-C irradiation, cis-resveratrol accumulated in the berries of the two varieties, while the differential chalcone, dihydroflavone, flavonoid, flavanol, and tannin components primarily accumulated in 'Xiangfei', and some flavonols and anthocyanins primarily accumulated in 'Zicui'. Based on an exhaustive survey, we made a summary for the effect of UV-C in regulating the quality development of post-harvest grape berries. The results of this study may help to elucidate the mechanism by which UV-C functions and support its efficient application.