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Although the role of WRKY transcription factors (TFs) in colour formation has been reported in several species, their function in potato (Solanum tuberosum L.) anthocyanin biosynthesis remains unclear. In this study, the potato WRKY gene StWRKY13 was isolated and characterised. Expression analysis revealed a significantly higher StWRKY13 expression in chromatic tubers than in yellow ones. Transient activation assays showed that StWRKY13 could enhance the role of StAN2 in promoting anthocyanin biosynthesis in tobacco (Nicotiana tabacum L.). Over-expressing the StWRKY13 gene promoted anthocyanin biosynthesis in potato tubers. Further investigations indicated that StWRKY13 could interact with the StCHS , StF3H , StDFR , and StANS gene promoters and significantly enhance their activities. Our findings showed that StWRKY13 could promote anthocyanin biosynthesis by activating StCHS , StF3H , StDFR , and StANS transcription in potato tubers, thereby supporting the theoretical basis for anthocyanins formation in coloured potato tubers. Anthocyanin can not only protect plants from biotic and abiotic stresses, but also play an important role in human health. Over-expressing the StWRKY13 gene promoted anthocyanin biosynthesis in potato (Solanum tuberosum L.) tubers, and the expression of StCHS , StF3H , StDFR and StANS could be significantly activated. This is the first report on the regulation of anthocyanin synthesis by WRKY gene in potato, so the findings enrich the theoretical basis for anthocyanin formation in coloured potato tubers. [ABSTRACT FROM AUTHOR]

• Expression of StANS in chromatic potato tubers is significantly higher than that in yellow ones. • StANS gene can promote anthocyanin synthesis in potato tubers. • StANS can be regulated by transcription factors StAN2 , StMYB113 and StAN11. Anthocyanin synthase (ANS), a key enzyme in anthocyanins synthesis, can convert the colorless leucoanthocyanins into colored anthocyanins. In this study, a potato anthocyanin synthase gene StANS was isolated and characterized. Expression analysis showed that the transcriptional expression of StANS in chromatic genotypes was significantly higher than that in yellow ones. Overexpressing the StANS gene could promote anthocyanin synthesis in potato tubers. Transient luciferase assays showed that the promoter of StANS could be activated by the transcription factors StAN2 , StMYB113 , and StAN11. These results indicated that the StANS gene, which was activated by the transcription factors StAN2 , StMYB113 , and StAN11 , could promote the anthocyanins synthesis in potato tubers. These findings provide a theoretical and applicable basis for anthocyanins formation in colored potato tubers. [ABSTRACT FROM AUTHOR]

• Transcription of StRAV1 in the yellow/white potato genotypes was significantly higher than in pigmented types. • StRAV1 inhibit anthocyanin formation in tobacco leaves by decreasing the expression of genes encoding related enzymes. • StRAV1 gene negatively regulates anthocyanin synthesis in potato tubers by directly inhibiting the transcription of StCHS, StANS and StF3'5'H. Previous studies on anthocyanin synthesis in potato mainly focus on the functions of anthocyanin biosynthetic structural genes and members of the MYB-bHLH-WD40 (MBW) complex. In this study, a RAV transcription factor StRAV1 was cloned. Expression analysis showed that the transcription of StRAV1 in yellow/white potato genotypes was significantly higher than in pigmented types. A transient activation assay showed that StRAV1 could inhibit anthocyanin formation in tobacco leaves by decreasing the expression of genes encoding related enzymes. Overexpression of StRAV1 in potato, led to significantly lower anthocyanin accumulation than in control tubers. The StCHS, StANS and St3'5'H promoters were significantly inhibited by StRAV1. These results suggest that the StRAV1 gene negatively regulates anthocyanin synthesis in potato tubers by directly inhibiting the transcription of StCHS, StANS and StF3'5'H. This is the first report on the regulation of anthocyanin synthesis in potato by a RAV gene, thus contributing to a more detailed understanding of this process. [ABSTRACT FROM AUTHOR]