Toward Characterization of and Breeder-friendly Molecular Markers for Genes Affecting Carotene accumulation in Carrot (Daucus carota)
The Y2 locus conditions α- and β-carotene accumulation in the xylem (core) of carrot roots. The dominant allele suppresses carotene, but not xanthophyll accumulation, resulting in yellow-cored roots. Individuals homozygous for the recessive allele are rich in carotenes and are therefore orange-cored. Increased consumer interest in high carotene produce requires improved understanding of carotene biosynthesis and color development and more-efficient breeding techniques. We examined 103 F2 individuals generated from inbred populations differing in core carotene content. Bulked segregant analysis identified AFLP bands putatively linked to Y2. Linkage was confirmed for some bands by mapping. Linked bands were excised from gels, re-amplified, cloned into pGEM vectors, and sequenced. Cloned fragments and sequence information were used to characterize larger genomic regions to identify codominant markers. Currently we are developing codominant, PCR-based markers that can be used to rapidly genotype individuals in breeding programs, to characterize wild, feral, and cultivated populations for diversity and evolution studies, and to examine the role of Y2 in carotene accumulation.