Genetic analysis of pigmented tuber flesh in potato

Interest in anthocyanin-pigmented potato tuber flesh is increasing. To genetically map and characterize loci that influence this trait, diploid potato clone 10618-01, which has partially pigmented flesh, was crossed with diploid 320-02, which has white flesh. Almost all progeny exhibited purple coloration in the flesh, with some clones having only a small percentage of tissue pigmented, other clones having most tissue pigmented, and the majority of clones showing intermediate color phenotypes. The two parents and 228 progeny were genotyped with 493 AFLP, 8 CAPS, and 13 SSR markers. QTLs influencing extent of flesh pigmentation were detected on chromosomes 5, 8, and 9. The potato homolog of Petunia an1, a basic helix-loop-helix (bHLH) transcriptional regulator of anthocyanin biosynthesis, was found to co-localize with the QTL on chromosome 9. A CAPS marker based on this gene was used to evaluate a collection of 21 tetraploid potato clones with highly or fully pigmented red or purple flesh, as well as 53 cultivars with white or yellow flesh. All 21 pigmented-flesh clones shared a marker allele that was present in only 21 of the 53 white and yellow clones, suggesting that a common bHLH allele contributes toward, although it is clearly not sufficient for, highly or fully pigmented tuber flesh in cultivated potato.