New disease-resistant grapevine varieties response to drought under a semi-arid climate

Introduction

In many regions, climate change leads to an increase in air temperature combined with a reduction of rainfall, intensifying climatic demand and water deficits (WD) (Cardell et al. 2019), which in turn may negatively impact grapevine development, yield and grape composition (Santos et al. 2020). In addition, climate change may also increase disease pressure, leading to further yield and quality losses, besides increasing costs due to increased vineyard spraying (Santos et al. 2020) and reducing viticulture acceptability by consumers (Guichard et al. 2017). Adopting new resistant varieties appears as a promising long-term solution to better manage vine protection, but unfortunately little is known regarding their behavior in front of WD. Indeed, most grapevine breeding programs do not consider drought performance as a primary attribute for selection, which is related to the difficulty to identify relevant phenotypes building a drought-performant behavior of a perennial fruit crop in the short and long terms.

Grapevine’s first acclimation to WD is the reduction of transpiring surfaces, reducing leaf area and canopy development (Simonneau et al. 2017) by primarily reducing secondary growth with later effects on main shoot (Pellegrino et al. 2005). Reproductive organs are also importantly affected by WD, normally leading to reductions in number of clusters, number of berries and berry weight, with greater impact if WD occurs during pre-véraison stage (Levin et al. 2020). In addition to these seasonal processes, the interseasonal effects include reduced reserve repletion and bud-fruitfulness (Guilpart et al. 2014), impairing vineyard longevity, a factor of great importance to be considered for a perennial fruit crop.

Despite many studies addressing WD effects on grapevine development and on grape yield and quality, there is a lack of knowledge regarding the plant processes involved in the acclimation from one season to the next, and how the new fungi-resistant genotypes behave in front of abiotic constraints, such as drought. Understanding these points is essential for anticipating vineyard durability and genotype selection in a changing climate.