Characterization of the F Locus Responsible for Floral Anthocyanin Production in Potato.

Anthocyanins are pigmented secondary metabolites produced via the flavonoid biosynthetic pathway and play important roles in plant stress responses, pollinator attraction, and consumer preference. Using RNA-sequencing analysis of a cross between diploid potato (Solanum tuberosum L.) lines segregating for flower color, we identified a homolog of the ANTHOCYANIN 2 (AN2) gene family that encodes a MYB transcription factor, herein termed StFlAN2, as the regulator of anthocyanin production in potato corollas. Transgenic introduction of StFlAN2 in white-flowered homozygous doubled-monoploid plants resulted in a recovery of purple flowers. RNA-sequencing revealed the specific anthocyanin biosynthetic genes activated by StFlAN2 as well as expression differences in genes within pathways involved in fruit ripening, senescence, and primary metabolism. Closer examination of the locus using genomic sequence analysis revealed a duplication in the StFlAN2 locus closely associated with gene expression that is likely attributable to nearby genetic elements. Taken together, this research provides insight into the regulation of anthocyanin biosynthesis in potato while also highlighting how the dynamic nature of the StFlAN2 locus may affect expression.