Thus, insertion of a non-infectious viral gene into a plant provides a sort of protective vaccine. Genes for resistance to fungi and bacteria work in different ways. Other genes act by creating holes in the membrane of fungal and bacterial cells. These membrane-active genes have been taken from a variety of organisms such as plants, mammals, amphibians, and insects. They have also been synthesized in the laboratory.
Much work is needed to test the numerous genes against grapevine pathogens.
Success in grapevine transformation came only when researchers started using what are termed embryogenic cultures. These cultures are grown in the laboratory under sterile conditions in an artificial growth medium. The cultures consist of tiny clumps of cells that are capable of growing into embryos that can germinate into plants. In our Geneva laboratory, we have taken a different approach. DNA coding for the genes of interest is coated onto the minute tungsten-microprojectiles.