Grapevines engineered to express cisgenic Vitis vinifera thaumatin-like protein exhibit fungal disease resistance

Cisgenic engineering involves isolation and modification of genetic elements from the host genome, which are reinserted to develop plant varieties with improved characteristics. As a first step toward production of fungal-disease resistant cisgenic grapevines, the Vitis vinifera thaumatin-like protein (vvtl-1) gene was isolated from “Chardonnay” and reengineered for constitutive expression. Embryogenic cultures of “Thompson Seedless” were initiated from leaves and transformed with Agrobacterium to regenerate cisgenic VVTL-1 plants. Cisgene presence and copy number were confirmed by PCR and quantitative real-time PCR. Protein expression was measured using ELISA. Among the plant lines tested, two exhibited a 7–10 day delay in powdery mildew disease development during greenhouse screening and decreased severity of black rot disease in field tests. Berries exhibited a 42.5% reduction in sour-bunch rot disease incidence compared to non-transformed controls after 3 wk of storage at room temperature. Although plants recovered in this study contain viral promoters and reporter/marker genes, this is the first report of a cisgenic approach to obtain broad-spectrum fungal-disease resistance in genetically engineered grapevine.