Application of new genomic technologies to improve the pathogen resistance of two local cultivars from Veneto region: Corvina and Garganega

Abstract

Grapevine (Vitis spp.) is a globally significant fruit crop and enhancing its agronomic and oenological traits is crucial to meet changing agricultural conditions and consumer demands.

The control of pathogens in viticulture often relies on the application of massive amounts of pesticides, especially fungicides, which comes at great costs for viticulture and poses a considerable risk for human health and the environment. Conventional breeding has played a key role in domesticating grapevine varieties, but it is a time-consuming process to develop new cultivars with desirable traits for cultivation, such as pathogen resistances. New plant genomic techniques (NGTs) offer a potential revolution in grapevine cultivation, and genome editing has shown promise for targeted mutagenesis. The success of these biotechnological approaches relies on efficient in vitro regeneration protocols, particularly through somatic embryogenesis (SE). This method has proven successful in some Vitis vinifera species, but its effectiveness varies due to the genotype-dependent nature of many cultivars. Moreover, protoplasts, cells without a cell wall, have proven to be particularly suitable for genome editing applications, but protoplasts regeneration remains generally considered challenging in grapevine. This approach preserves the genetic identity of the cultivars, which would otherwise be altered through crossing.

The focus of this study is to enhance in vitro plant regeneration process via SE and isolate and regenerate plants from protoplasts derived from embryogenic calli of Corvina and Garganega, two grapevine varieties of significant economic importance for wine production in the Veneto region. Protoplasts serve as a platform for DNA-free genome editing using CRISPR/Cas9 system to target MLO and DMR Susceptibility S-genes associated with downy mildew and powdery mildew susceptibility in grapevine. The study includes a preliminary phenotypic characterization of powdery mildew and downy mildew infections to evaluate the reduction of susceptibility to pathogens in the edited-regenerated plants. This research aims to accelerate the development of grapevine varieties with improved traits, overcoming the limitation of conventional breeding methods and this advancement aligns with European legislative demand about NGT plants.