Genetic and Genomic Approaches for Adaptation of Grapevine to Climate Change
The necessity to adapt to climate change is even stronger for grapevine than for other crops, because grape berry composition—a key determinant of fruit and wine quality, typicity and market value— highly depends on “terroir” (complete natural environment), on vintage (annual climate variability), and on their interactions. In the same time, there is a strong demand to reduce the use of pesticides. Thus, the equation that breeders and grape growers must solve has three entries that cannot be dissociated: adaptation to climate change, reduction of pesticides, and maintenance of wine typicity. Although vineyard management may cope to some extent to the short–medium-term effects of climate change, genetic improvement is necessary to provide long-term sustainable solutions to these problems. Most vineyards over the world are planted using vines that harbor two grafted plants’ genomes. Although this makes the range of interactions (scion-atmosphere, rootstock-soil, scion-rootstock) more complex, it also opens up wider possibilities for the genetic improvement of either or both the grafted genotypes. Positive aspects related to grapevine breeding are as follows: (a) a wide genetic diversity of rootstocks and scions that has not been thoroughly explored yet; (b) progress in sequencing technologies that allows high-throughput sequencing of entire genomes, faster mapping of targeted traits and easier determination of genetic relationships; (c) progress in new breeding technologies that potentially permit precise modifications on resident genes; (d) automation of phenotyping that allows faster and more complete monitoring of many traits on relatively large plant populations; (e) functional characterization of an increasing number of genes involved in the control of development, berry metabolism, disease resistance, and adaptation to environment. Difficulties involve: (a) the perennial nature and the large size of the plant that makes field testing long and demanding in manpower; (b) the low efficiency of transformation, regeneration and small size of breeding populations; (c) the complexity of the adaptive traits and the need to define more clearly future ideotypes; (d) the lack of shared and integrative platforms allowing a complete appraisal of the genotype-phenotype-environmental links; (e) legal, market and consumer acceptance of new genotypes. The present chapter provides an overview of suitable strategies and challenges linked to the adaptation of viticulture to a changing environment.