Effects of StSP6A overexpression and silencing on potato stolons

Summary StSP6A is a protein with sequence homology to the Arabidopsis FLOWERING LOCUS T (FT). FT is a main component of the long range flowering promoting signal or florigen that induces photoperiodic flowering under long days (LDs). In potato, short days (SDs) promote tuber induction, and wild subspecies like Solanum tuberosum ssp andigena (wild type line 7540) are strictly dependent on SDs to tuberize. StSP6A transcription is induced in leaves and stolons at early stages upon transfer to SD inductive conditions, priotr to visible solon swelling. Transgenic andigena lines over-expressing the StSP6A gene under the control of the 35S promoter are able to tuberize under LD non-inductive conditions, whereas silencing of this gene by means of an specific RNAi construct are strongly delayed in tuber induction in SD inductive conditions. This data indicate that StSP6A plays a central role in the control of tuber induction. For each sample of the two comparisons (35S-StSP6A versus Wild Type and StSP6A-RNAi versus Wild Type) two biological replicates were prepared. In the case of 35S-StSP6A and StSP6A-RNAi each replicate was composed by a pool of several transgenic lines.