Genetic transformation of Vitis vinifera via organogenesis

Background: Efficient transformation and regeneration methods are a priority for successfulapplication of genetic engineering to vegetative propagated plants such as grape. The currentmethods for the production of transgenic grape plants are based on Agrobacterium-mediatedtransformation followed by regeneration from embryogenic callus. However, grape embryogeniccalli are laborious to establish and the phenotype of the regenerated plants can be altered.Results: Transgenic grape plants (V. vinifera, table-grape cultivars Silcora and Thompson Seedless)were produced using a method based on regeneration via organogenesis. In vitro proliferatingshoots were cultured in the presence of increasing concentrations of N6-benzyl adenine. The apicaldome of the shoot was removed at each transplantation which, after three months, producedmeristematic bulk tissue characterized by a strong capacity to differentiate adventitious shoots.Slices prepared from the meristematic bulk were used for Agrobacterium-mediated transformationof grape plants with the gene DefH9-iaaM. After rooting on kanamycin containing media andgreenhouse acclimatization, transgenic plants were transferred to the field. At the end of the firstyear of field cultivation, DefH9-iaaM grape plants were phenotypically homogeneous and did notshow any morphological alterations in vegetative growth. The expression of DefH9-iaaM gene wasdetected in transgenic flower buds of both cultivars.Conclusions: The phenotypic homogeneity of the regenerated plants highlights the validity of thismethod for both propagation and genetic transformation of table grape cultivars. Expression of theDefH9-iaaM gene takes place in young flower buds of transgenic plants from both grape cultivars.