VvGA2ox5 positively improves drought tolerance in grapevine by activating the hormone signal transduction pathway

Gibberellin 2-oxidases (GA2ox) play an important role in regulating the balance of bioactive gibberellins in plants, while their role in the drought response mechanism of grapes remains unclear. In this study, the subcellular localization analysis revealed that the VvGA2ox5 protein was predominantly localized to the cytoplasm and nucleus. Transient transformation experiments on ‘Pinot noir’ grape leaves showed that overexpression of VvGA2ox5 reduced relative electrical conductivity (REC) and malondialdehyde (MDA) levels and increased proline content, antioxidant enzyme activity, and expression of drought-responsive genes. In contrast, virus-induced gene silencing (VIGS) silenced leaves showed the opposite results. Additionally, the overexpression of VvGA2ox5 in ‘Pinot noir’ grape calli and Arabidopsis thaliana (Arabidopsis) further validated its positive function. In CRISPR-Cas9-edited grape calli, the results were opposite to those of overexpression lines. Meanwhile, yeast two-hybrid (Y2H) screening identified a drought-responsive protein, dehydration-induced 19 homolog 3 (VvDEH). RNA-seq analyses showed that overexpression of VvGA2ox5 significantly participates in the hormone signaling pathway. Accordingly, VvGA2ox5 is a crucial regulatory gene in enhancing drought tolerance in grapes and serves as a potential candidate gene for improving drought tolerance in plants. This finding offers significant theoretical support for drought tolerance breeding in grapes.