Integrated Transcriptomic and Proteomic Analysis Reveals Genes Associated with Plant Growth Regulator-induced Astringency Changes in Grape Berries

Astringency influences the sensory characteristics and flavor quality of table grapes. We tested the astringency sensory attributes of berries and investigated the concentration of flavan-3-ols/proanthocyanidins in skins after the application of the plant growth regulators CPPU and GA3 to the flowers and young berries of Summer Black grape. Our results showed that CPPU and GA3 applications increase sensory astringency perception scores and flavan-3-ol/proanthocyanidin concentrations. Using integrated transcriptomic and proteomic analysis, differentially expressed transcripts and proteins associated with growth regulator treatment were identified including those for flavonoid biosynthesis that contribute to the changes in sensory astringency levels. Transient overexpression of candidate astringency-related genes in grape leaves revealed that VvWRKY71 in combination with VvMYBPA1 and VvMYC1 could promote the biosynthesis of proanthocyanidins, while overexpression of VvNAC83 reduced the accumulation of proanthocyanidins. This study provides new insights into the molecular mechanisms of sensory astringency formation induced by plant growth regulators in grape skin.