Hybrid potato breeding for improved varieties

The cultivated potato, Solanum tuberosum, can be reproduced generatively through seeds and vegetatively through tubers. This may have evolutionary advantages: seeds may provide better survival under extreme conditions, such as frost or drought, and can remain viable in the soil for years. When conditions are mild, tubers survive in a dormant state for a couple of months. When conditions become favourable again, their fast and strong sprouting provides a clear competitive advantage over other plants in the same ecological niche. In traditional potato breeding, each breeding cycle starts with a cross between two genotypes, usually tetraploid varieties, followed by many years of selection and multiplication (see Chapters 2 and 3). The advantage of this approach is uniformity: the tubers are clones and thus genetically identical. The disadvantage is the low genetic gain in each lengthy breeding cycle, as the genetic composition of the two parental genotypes is just reshuffl ed, including alleles which negatively affect plant growth and development. As a result, potato yield has not signifi cantly been improved over the past century (Douches