The inheritance of anthocyanin pigmentation in potato (Solanum tuberosum L.) and mapping of tuber skin colour loci using RFLPs.

Two existing genetic models for anthocyanin pigmentation are compared: the genetic model as proposed by Lunden (1937, 1960, 1974) for tetraploid potato Solanum tuberosum group Tuberosum and the model by Dodds & Long (1955, 1956) for diploid cultivated Solanum species. By crossing well defined genotypes from both genetic sources it was demonstrated that locus R/Rpw and locus D are allelic. Both loci are involved in the biosynthesis of red anthocyanins. We propose to maintain the symbol D for this locus. Tuber skin colour is expressed due to the complementary action of one locus involved in anthocyanin biosynthesis and a second locus involved in tissue-specific regulation of anthocyanin expression. The inheritance of two phenotypes of skin colour was investigated in this study: pigmentation of the epidermis and pigmentation of the cortex. In two different populations the loci determining the two phenotypes were located with RFLPs on the map of the potato genome, at approximately the same position as the earlier mapped PSC locus on chromosome 10. Lunden proposed the symbols E and R for the loci determining these phenotypes. Dodds and Long proposed only one locus I for tuber skin colour without describing these different phenotypes. The identity and nomenclature of the loci studied by the various authors are discussed.