Genetic control of anthocyanin pigmentation of potato tissues

The cultivated potato Solanum tuberosum L. is the fourth most important crop worldwide. Anthocyanins synthesis and accumulation in potato tissues are considered as one of important traits related to stress resistance and nutritional value. It is considered that the major regulatory gene for anthocyanin biosynthesis is R2R3 MYB-encoding gene StAN1. However, the genetic control of pigmentation of different potato tissues is substantially under investigated. The development of genetic markers for breeding of potato with specific pigmentation pattern remains an actual task.

We investigated 36 potato varieties and hybrids with different pigmentation of tubers and leaves. Sequence organization of regulatory R2R3 MYB (StAN1, StMYBA1, StMYB113), bHLH (StbHLH1, StJAF13) and WD40 (StWD40) genes potentially controlling anthocyanin biosynthesis has been evaluated. The results demonstrated a high variability in the StAN1 third exon and promoter region with the exception for 35 bp, containing elements for the transcription start and activation of gene expression in roots. The analysis of transcriptional activity of genes coding R2R3 MYBs, bHLHs and WD40 transcriptional factors in leaves of eight potato genotypes with different anthocyanin pigmentation was performed. The results showed a relation between the gene expression level and plant pigmentation only for the StAN1 and StWD40 genes, while other studied genes had either strong expression in all varieties and hybrids (StMYBA1, StbHLH1 and StJAF13) or they were not expressed at all (StMYB113).

It was found that StAN1 is the major regulatory gene controlling potato anthocyanin synthesis. However, diagnostic markers developed for the functional StAN1 alleles (StAN1⁷⁷⁷ and StAN1⁸¹⁶) can not be used efficiently for prediction of potato pigmentation patterns. It is likely that the sequence organization of StAN1 promoter is important for anthocyanin synthesis control and the development of additional diagnostic markers is necessary.