Naturally occurring allele diversity allows potato cultivation in northern latitudes

A genetic study of natural variation in potato tuberization onset, an important phenotype for breeding potatoes adapted to different global day lengths, has revealed a role for StCDF1 , a member of the DOF family of transcription factors. Potatoes take northerly route Potatoes were introduced into Europe from the Andes in the sixteenth century. In South America the plants had adapted to form tubers under short-day conditions, so one of the first traits likely to have been selected by growers would have been for tuber production in the long days of spring and summer encountered in northern latitudes. Christian Bachem and colleagues have cloned the gene responsible for early tuberization under long-day conditions. It encodes a DOF transcription factor that acts as a mediator between the circadian clock and the StSP6A tuberization signal. The natural allelic variation of this protein is sufficient for it to have been the basis of the domestication of the potato in latitudes where there is large summer/winter day-length variation. Breeding programmes selecting for further variants could take potatoes into new geographic regions. Potato ( Solanum tuberosum L.) originates from the Andes and evolved short-day-dependent tuber formation as a vegetative propagation strategy. Here we describe the identification of a central regulator underlying a major-effect quantitative trait locus for plant maturity and initiation of tuber development. We show that this gene belongs to the family of DOF (DNA-binding with one finger) transcription factors 1 and regulates tuberization and plant life cycle length, by acting as a mediator between the circadian clock and the StSP6A mobile tuberization signal 2 . We also show that natural allelic variants evade post-translational light regulation, allowing cultivation outside the geographical centre of origin of potato. Potato is a member of the Solanaceae family and is one of the world’s most important food crops. This annual plant originates from the Andean regions of South America 3 . Potato develops tubers from underground stems called stolons. Its equatorial origin makes potato essentially short-day dependent for tuberization and potato will not make tubers in the long-day conditions of spring and summer in the northern latitudes. When introduced in temperate zones, wild material will form tubers in the course of the autumnal shortening of day-length. Thus, one of the first selected traits in potato leading to a European potato typ