Day length dependent restructuring of the leaf transcriptome and metabolome in potato genotypes with contrasting tuberization phenotypes

Recent advances have defined some of the components of photoperiodic signalling that lead to tuberization in potato including orthologues of FLOWERING LOCUS T (StSP6A) and CYCLING DOF FACTOR (StCDF1). The aim of the current study is to investigate the molecular basis of permissive tuber initiation under long days in Solanum tuberosumNeo-Tuberosum by comparative analysis with an obligate short-day S.tuberosum ssp. Andigena accession. We show that the Neo-Tuberosum accession, but not the Andigena, contains alleles that encode StCDF1 proteins modified in the C-terminal region, likely to evade long day inhibition of StSP6A expression. We also identify an allele of StSP6A from the Neo-Tuberosum accession, absent in the Andigena, which is expressed under long days. Other leaf transcripts and metabolites that show different abundances in tuberizing and non-tuberizing samples were identified adding detail to tuberization-associated processes. Overall, the data presented in this study highlight the subtle interplay between components of the clock-CONSTANS-StSP6A axis which collectively may interact to fine-tune the timing of tuberization. The molecular mechanisms that control tuber formation have been investigated in detail over the past few decades because the control of tuber initiation, number and size uniformity is probably the largest economic constraint of modern potato production. Recent breakthroughs have identified components of the photoperiodic signalling pathway that leads to tuberisation. In this work we have characterised the biochemical and transcriptional responses in two divergent potato genotypes under contrasting day length regimes and revealed new insights into tuberisation and associated processes. Furthermore, we reveal the intriguing presence of an additional StSP6A allele that is associated with tuber formation under long day length conditions. Overall, the data presented in this study highlight the subtle interplay between components of the clock-CONSTANS-StSP6A axis which collectively may interact to fine-tune the timing of tuberisation.