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Abstract

Potato was domesticated in the South American Andes and was initially introduced to Europe in the 16th century. Over time it played increasingly important role as a food source. To tuberize before winter in Europe, potato had to adapt to shorter growing season through photoperiod insensitivity. Molecular mechanism of such adaptation in modern cultivars is thought to be exclusively attributed to structural variation in StCDF gene. We collected herbarium specimens of European cultivated potato dated between 1660-1899 AD to investigate the genomics of potato introduction in Europe. We successfully optimized extraction protocols to facilitate library-based re-sequencing of highly degraded DNA from old herbarium samples. Subsequently, we utilized hybridization array to capture regions with curated nuclear SNPs, whole chloroplast genome and over 300 genes related to photoperiod response. Comparison of nuclear SNPs and chloroplast assemblies between historic and modern potato samples unveiled waves of migrations that changed European gene pool between 19th and 20th century. We uncovered increase in genetic diversity of European potato in last hundred years, suggesting continuous influx of South American germplasm. We showed that historic European samples carry a structural variant of StCDF that confers adaptation to European climate, however, only at low frequencies. Finally, we report changes in nucleotide diversity in other genes that could be relevant to the process of adaptation. In summary, we present an interesting case of crop’s recent adaptation to new environment and provide compelling evidence for the complexity of such scenarios.