Strategies in the Genetic Selection of Clones and the Preservation of Genetic Diversity within Varieties

Grapevine varieties are far older than varieties of other domestic species. Many of them may go back to ancient Greek and Roman times. Due to mutations and their predominantly vegetative propagation, a certain genetic range has developed within varieties during the many centuries of their existence. In some cases mutations effected clearly visible characters, e.g. berry colour or ripening time, resulting in varieties like Pinot Gris or Pinot Blanc out of Pinot Noir or Pinot Madeleine out of Pinot Noir. But in most cases mutations were less pronounced, still staying in the range of the original variety. Pinot noir is a good example for the extend of genetic variation within varieties. Large variations were found in regards to yield, acidity, botrytis infection, pedicel length and berry size. Sugar content and must pH varied far less. Mutations are the source for this variation, which is utilized for genetic selection and the development of new clones with different characters and performance. In most countries clonal selection schemes have been set up by now. Despite its many positive effects, clonal selection at the same time is also a threat to itself: If only clonal material is planted, other genotypes will soon disappear from vineyards and with it the source for new and different clones. Successful clonal selection requires genetic variation and destroys it at the same time. With a wine industry, that constantly changes, the requirements for clones will change as well. What is discarded today, might be the clone for tomorrow. The collection and preservation of genetically diverse material is the first measure to prevent this from happening. With the large number of scion varieties used in Europe this is a major task and raises the question: What is worth keeping and how do we best do this? Collecting material indiscriminately will soon result in huge plantings and repeats of identical genotypes over and over again. Therefore an assessment based on performance of molecular genetic methods will be required.