Detection of anthocyanin biosynthesis key genes and their restriction fragment patterns in colourful and white cultivars of Solanum tuberosum

The health aspects of vegetables containing high anthocyanin has increased the consumption of colored potatoes rich in anthocyanin in recent years. Anthocyanin’s in blue and purple potatoes are derived from delphinidin, while in the red ones they are resulted from pelargonidin. Three genes, D, P and R interact for production of delphinidin and pelargonidin within the anthocyanin biosynthesis pathway that eventually results in colored potato flesh. Studying genetic and allelic relations among these three major genes provides a better understanding of anthocyanin biosynthesis pathway in potato. In this research, 17 potato genotypes of varying tuber color were used to detect the three key genes of D, P and R using specific primers and to compare their restriction fragment patterns. Results showed that purple genotypes contained the dominant allele for the P locus and the white and the red genotypes had the recessive allele. The white colored potatoes contained only the r allele in a homozygous state while the red and purple colored potatoes had both R and r alleles in a heterozygous condition masking the phenotypical presence of r. Restriction fragment patterns of the PCR products clearly revealed that none of the white potato genotypes possessed the D allele but the colored genotypes contained both D and d alleles in a heterozygous condition with an unknown allelic arrangements. D is an important regulatory gene for both P and R genes and the dominant allele D is required for their expression and anthocyanin production in the potato tuber. In other words, having dominant alleles of P and R in a potato plant does not necessarily give colored potato if the dominant allele D is not present. Albeit, restriction fragment pattern procedure discriminated the colored genotypes from the white tuber ones in P and R genes but primarily determination of D locus dominant status as a key regulatory factor in anthocyanin biosynthesis pathway is more important.