Interactions between auxin and quercetin during grape berry development

•The expression of CHS protein was detected by western blot analysis and immunohistochemical localization.•Flavonoids contents and the key enzymes involved in auxin metabolism were detected.•Study of the interaction between auxin and flavonoids in grape berry will be helpful to control the fruit quality formation.

Both flavonoids and auxin are plant growth regulators with critical physiological roles. In this study, the interaction between auxin and flavonoids was investigated using grape berries treated with quercetin, IAA and NPA. The results showed that exogenous IAA enhanced the expression of the CHS protein and increased the accumulation of the total flavonoids in the grape berry. IAO and POD activities were significantly reduced by supplemental quercetin in grape berries at 30 DAF. However, no obvious variations were detected in grape berries at 60 DAF. These observations indicate that flavonoids and auxin may have different interaction mechanisms and physiological roles during grape berry development. These data contribute to the understanding of the relationship between the flavonoids and auxin in plant reproduction and the formation mechanism of fruit quality.