Jan and mini-Jan, a model system for potato functional genomics.

Potato (Solanum tuberosum) is the third-most important food crop in the world. Although the potato genome has been fully sequenced, functional genomics research of potato lags behind that of other major food crops, largely due to the lack of a model experimental potato line. Here, we present a diploid potato line, 'Jan,' which possesses all essential characteristics for facile functional genomics studies. Jan exhibits a high level of homozygosity after seven generations of self-pollination. Jan is vigorous, highly fertile and produces tubers with outstanding traits. Additionally, it demonstrates high regeneration rates and excellent transformation efficiencies. We generated a chromosome-scale genome assembly for Jan, annotated its genes and identified syntelogs relative to the potato reference genome assembly DMv6.1 to facilitate functional genomics. To miniaturize plant architecture, we developed two 'mini-Jan' lines with compact and dwarf plant stature through CRISPR/Cas9-mediated mutagenesis targeting the Dwarf and Erecta genes involved in growth. One mini-Jan mutant, mini-Jan, is fully fertile and will permit higher-throughput studies in limited growth chamber and greenhouse space. Thus, Jan and mini-Jan offer a robust model system that can be leveraged for gene editing and functional genomics research in potato.