With the title: “Naturally occurring allele diversity allows potatoes cultivation in northern latitudes” Nature (2013: 495, 246-60) published the identification the central trait underlying the natural variation on potato formation. This work offers to breeders the possibility to select potatoes varieties for different latitudes, harvest times and markets.
Potatoes originate from Andean regions of South America. This equatorial origin makes potatoes a short-day cultivar; the formation of potatoes (tuberization) depends on this light condition and they don’t produce tubers in long-day conditions of spring/summer in northern latitudes. Due to natural occurring allele diversity, potato breeders first selected traits to produce tubers in long-day conditions that lead to European Potato Type. Until this month, potato breeders know that the potato plant maturity phenotype was a quantitative trait loci (QTL) mapping on Chromosome 5. Breeders score this phenotype as a measure for several important sub-traits, including; 1) Onset of leaf senescence; 2) Total length of the plant life cycle; 3) Time point of tuberization; and 4) Potato yield. This picture is going to change after the work published from European researcher at AB Waggeningen, Utrech University and Centro Nacional de Biotecnología – CSIC that identified the central regulator underlying tuber formation.
The researchers used two diploid populations, derived from wild and domesticated genotypes potatoes to map the plant maturity QTL, and identified CDF1 - a gene that belongs to DOF family (DNA-binding with One Finger) transcription factor - as candidate on Chromosome 5. They demonstrate CDF1 function as maturity gene by transforming short-day dependent phenotype plants that formed tubers on long-day conditions. The major role for CDF1 gene for plant maturity was verified in the wider gene pool of cultivated potato. A genome-wide association study, using a representative set of 83 potato cultivars, allowed the identification of highlight significant marker-by-trait association for single nucleotide polymorphism (SPN) marker within a short-range linkage disequilibrium with the casual insertion polymorphism in CDF. This was the only trait that caused phenotypic variation in plant maturity. CDF acts as a mediator between the circadian clock and the protein controlling the storage organ formation. The authors proposed a model for the induction of tuberitzation that explained how natural allelic variants of CDF evade post-translational light regulation, allowing the cultivation of potato crops outside of the geographical centre of origin.
If you would like to know more of the uncovering of the mechanism underpinning the domestication of potatoes and how could help in the future to tailor breeding for new geographic regions follow this link to the research paper.