Grapevine resistance to pathogens: a genomic overview

Grapevine (Vitis vinifera L.) is the most widely grown fruit crop with an annual production of more than 67 million tons, while its derivatives have a large and expanding world-wide market. However, grapevine cultivars are susceptible to many pathogens, either by direct infection of the berries themselves or through the reduction of plant vigour, both of which reduce fruit quality and yield. Disease control is currently carried out by intensive use of pesticides, with an undesirable environmental impact. To reduce excessive use of phytochemicals in the vineyard, alternative strategies have been explored. Many longstanding breeding programmes have been established in the past aimed at combining V. vinifera fruit quality traits with resistance traits brought in by other Vitis species. This has, however, proved to be a difficult task, due to the quantitative nature of resistance determination, the long generation time, and the high heterozygosity and inbreeding depression of grapevines. The recent discovery of the Pinot Noir genome sequence represents an important new resource in tackling the problem and provides us with the possibility of defining the genomic regions responsible for resistance traits and of identifying the candidate genes underlying the known resistance Quantitative Trait Loci (QTLs).