Insights into Long-Term Acclimation Strategies of Grapevines (Vitis vinifera L.) in Response to Multi-Decadal Cyclical Drought

Changing climatic conditions across Australia's viticulture regions is placing increasing pressure on resources such as water and energy for irrigation. Therefore, there is a pressing need to identify superior drought tolerant grapevine clones by exploring the extensive genetic diversity of early European clones in old vineyards. Previously, in a field trial, we identified drought-tolerant (DT) dry-farmed Cabernet Sauvignon clones that had higher intrinsic water use efficiency (WUEi) under prolonged soil moisture deficiency compared to drought-sensitive (DS) clones. To investigate whether the field-grown clones have been primed and confer the drought-tolerant phenotypes to their subsequent vegetative progenies, we evaluated the drought responses of DT and DS progenies under two sequential drought events in a glasshouse alongside progenies of commercial clones. The DT clonal progenies exhibited improved gas exchange, photosynthetic performance and WUEi under recurrent drought events relative to DS clonal progenies. Concentration of a natural priming agent, gamma-amino butyric acid (GABA), was significantly higher in DT progenies relative to other progenies under drought. Although DT and commercial clones displayed similar drought acclimation responses, their underlying hydraulic, stomatal and photosynthetic regulatory mechanisms were quite distinct. Our study provides fundamental insights into potential intergenerational priming mechanisms in grapevine.