Grapevine breeding for the development of multi-disease-resistant cultivars through marker-assisted selection and resistance gene pyramiding

Abstract

The climatic conditions of southern Brazil favor the incidence of fungal diseases in grapevines, which hampers the cultivation of Vitis vinifera varieties. In addition to downy mildew and powdery mildew, anthracnose and bunch rots are major diseases that require control by fungicides. More recently, resistant cultivars (“PIWIs”) have been developed that consist largely of a V. vinifera genetic background but include the introgression of a few resistance genes, thereby reducing dependence on chemical products. Abreeding program with this objective is being conducted in the state of Santa Catarina, Brazil (Epagri/UFSC program), aiming to develop high-quality wine grape cultivars resistant to the main grapevine diseases (downy mildew, powdery mildew, anthracnose, and grape ripe rot (Colletotricum sp.)). The genetic basis of the program includes currently available resistant varieties and additional sources of resistance to fungal diseases. Selection for downy mildew resistance is carried out at the early seedling growth stage using molecular markers. For downy mildew, the loci Run1/Rpv1, Rpv3, Rpv10, and Rpv12 are monitored, with the goal of selecting individuals carrying at least three of these genes. Selection for powdery mildew resistance is based on the Run1 gene. Selected seedlings are evaluated for anthracnose resistance through artificial inoculation under controlled conditions. The source of anthracnose resistance originates from V. amurensis and was initially identified in the cultivar Sibera. After evaluation for resistance to the three diseases, selected materials are grafted and multiplied for planting under commercial vineyard conditions, where they are assessed for agronomic traits, resistance to bunch rots, and oenological quality. Initial evaluations have shown that canopy health in pyramided multi-resistant materials is superior to that of most resistant cultivars currently under testing. Enological evaluations started in 2024. The program will continue in the coming years through successive cycles of crosses, marker-assisted selection, and field evaluation for agronomic and oenological traits.

Acknowledgements

FAPESC (funding agency).