Transgenic Resistance: State of the Art and Perspectives

Introduction Grapevine viruses can cause severe losses by substantially reducing yield, affecting fruit quality, and shortening the lifespan of infected plants in the vineyard. Strategies to control viruses are essentially preventive with sanitary selection programs or directed to eradicate virus vectors with agrochemicals. These strategies are effective at limiting the presence of viruses in propagation material and reducing the infectious potential of vectors. However, their practical impact is somewhat limited if new plantings are established in areas with a long history of monoculture of grapes. Moreover, concerns have been expressed on the use of agrochemicals used to control virus vectors, and even restrictions applied, because of their acute toxicity and adverse effects on the environment. Due to the severity of viral epidemics, the difficulties of implementing efficient control strategies, and the increasing demand for sustainable and environmentally-safe viticulture practices, there is a great need to develop varieties that are resistant to viruses. Virus resistance has not been achieved in elite varieties yet because genes for resistance have not been found or the few sources of resistance that have been identified are difficult to transfer by conventional breeding. Genetic transformation is an attractive alternative for genetic improvement of grapes because it potentially elevates the shortcomings of conventional approaches by allowing the insertion of specific virus resistance traits directly into desirable elite varieties.