Segregation of Total Carotenoid in High Level Potato Germplasm and Its Relationship to Beta-Carotene Hydroxylase Polymorphism

High carotenoid potato may have particular value for human health due to the antioxidant properties and the therapeutic value for eye health in patients at risk for macular degeneration. Carotenoid concentrations were determined among the progeny of a cross between two high carotenoid lines derived from diploidPapa Amarilla germplasm from South America. The total carotenoid content ranged from 82 to 2686 μg / 100 g fresh weight (FW). The higher values greatly exceeded the mid-parent value of the cross. An index for yellow tuber flesh color was determined for a subset of the progeny. A cleaved amplified polymorphic sequence (CAPS) assay was developed to distinguish the alleles of beta-carotene hydroxylase (bch) in the two high-carotenoid parents. Abch allele (denoted B) common to the high carotenoid parents co-segregated with yellow flesh in the progeny of a white-flesh x yellow-flesh cross, makingbch an excellent candidate for the classicalY locus, required for yellow tuber flesh. The same allele was also present in all other yellow-fleshed potato clones tested. Genotype atbch explained a portion of the variation of total carotenoid (R2=0.42). Clones homozygous for the B allele (BB) contained, on average, slightly more carotenoid than heterozygous Bb clones, which in turn had much more carotenoid than homozygous bb clones, suggesting a partially dominant gene model. Similarly, bb flesh was significantly less yellow than Bb and BB, the latter two being quite close. Total carotenoid varied considerably between progeny in the Bb and BB genotype categories, suggesting that variation at one or more additional loci have a significant effect on total carotenoid levels. Since the total carotenoid levels in manyPapa Amarilla cultivars and progeny are much higher than those in white- and yellow-fleshed tetraploid cultivars, it may be possible to breed for high carotenoid values in tetraploid germplasm by introducing one or more genes derived fromPapa Amarilla germplasm.