The function of the GIGANTEA gene StGI.04 in potato: Uncovering a new function affecting the anthocyanin content of tuber skin

GIGANTEA (GI) is a plant-specific, circadian clock-regulated, nuclear protein with pleiotropic functions studied in many plant species. It is involved in flowering, circadian clock control, chloroplast biogenesis, carbohydrate metabolism, stress responses and synthesis of volatiles. In potato (Solanum tuberosum L.), however, only its role in tuber initiation is reported. Based on the findings in other plant species we hypothesized that the function of GI is not restricted to tuberization in potato. To test this hypothesis we repressed the expression of a GI gene, StGI.04 in the commercial potato cultivar ‘Désirée’ and investigated the effect of repression at morphological and transcriptome level. We found that, like GI in other plant species, StGI.04 influences the expression of the key genes of circadian clock, flowering, starch synthesis and stress responses. Furthermore, we detected a novel function of a GI gene in influencing the anthocyanin synthesis and skin colour of potato tubers. RNA-seq of leaves of a StGI.04-repressed (aGI) potato line compared to the non-transformed control 'Désirée' (DES)