Isolated disease-related genes from muscadine (Vitis rotundifolia) and Florida hybrid bunch grape (Vitis spp.) grapes, and complementary DNA associated therewith. The cDNA can be utilized in small RNA technologies to promote expression of disease tolerance-related genes to induce production of disease-tolerance related gene products for resisting disease occurrence in Florida hybrid bunch and V. vinifera. The genes include, but are not limited to, stilbene synthase, chalcone synthase, chitinase, PR 4, PR 10, β-1, 3-glucanase, peroxidase, and a subunit of Oxygen-Evolving Enhancer Protein 1. These genes were found to enhance tolerance of Florida hybrid bunch and muscadine grape to a plurality of pathogenic diseases, including, for example, Pierce's disease and anthracnose.