Brassinolide and gibberellin promote grape fruit development and quality

Brassinosteroid (BR) and Gibberellins (GA) are important hormones that significantly influences grapeberry development and ripening. In the present study, grape clusters were soaked separately with EBR (Epi brassinolide), GA(3), and EBR+GA(3) during fruit development. Results showed that anthocyanin content, soluble solids, and titratable acid content were all enhanced by EBR treatment, however fruit weight, transverse and longitudinal longitude, and hardness were not significantly changed, furthermore, GA(3) treatment increased the fruit weight, longitudinal and transverse longitude, and hardness, decreased titratable acid, and increased the solid acid ratio; The EBR+GA(3) significantly improved grape fruit quality, increased fruit anthocyanin content, reduced titratable acid content, improved sugar-acid ratio, and significantly improved fruit weight, transverse and longitudinal longitude, and hardness. EBR and GA(3) treatment increased the contents of alcohols, esters, ketones, terpenes, and phenols in aroma substances, and glucose and fructose. They also increased the sugar, aroma, and anthocyanin metabolism-related genes, while down-regulated the expression of acid-related genes. EBR also increased the GA metabolism associated genes, but GA(3) decereaed BR metabolism assocated genes. BR and GA had a crosstalk of that VvGAI could interact with VvBZR1, VvGAI could inhibit the VvBZR1 binding to the VvGA20ox2 promoter that decreased the VvGA20ox2 gene expression, but EBR and GA(3) could alleviate the inhibition. In conclusion, both BR and GA alone could improve fruit quality to some extent, and the combination of them can better integrate the advantages of single-use to improve the fruit quality and enhance the commerciality of the grape fruit.