The preservation of genetic resources of the vine requires cohabitation between institutional clonal selection, mass selection and private clonal selection

Abstract

Clonal selection allows control of virus diseases and selection of genotypes on agronomic, viticultural or enological criteria. Clonal selection has the major drawback that it impoverishes genetic diversity and exposes growers to environmental instability of clones (genotype X environment interaction). Clonal selection has become the almost unique way of propagating plant material for vineyards, hence threatening the genetic diversity of the grapevine. For major grapevine varieties, some genetic diversity is maintained in institutional collections. However, this way of conservation is insufficiently developed, it is expensive and remains fragile. A cost effective way to preserve intra-varietal diversity is to maintain a limited proportion of mass selection in vine propagation. Private clonal selection can also contribute, in a more limited way, in maintaining genetic resources. Another approach to carry out conservation and selection of grapevine is the methodology followed in Portugal. This strategy is exemplified with the conservation/selection of an ancient Portuguese variety. The work begins with the “ex situ” conservation of a representative sample of the intravarietal diversity of the variety, which, in practice, corresponds to a large field trial with hundreds of clones under an experimental design suitable for reducing random variation of quantitative traits. From evaluating those traits (yield and must quality traits), the intravarietal diversity is quantified and the range of the predicted genotypic effects for each of those traits is analyzed. Different mass selections (polyclonal selections) are carried out for distribution and planting of new vineyards. These different mass selections provide high economic gains and also the preservation of diversity in a complementary manner to that which started the work on-farm conservation.