Segregations for Onion Bulb Colors Reveal That Red Is Controlled by at Least Three Loci

Abstract

Onion (Allium cepa L.) bulb color is controlled by at least five major loci (I, C, G, L, and R) and seedcoat color by one locus (B). The authors developed families segregating for bulb and seedcoat colors, simple sequence repeats (SSRs), and single nucleotide polymorphisms (SNPs) in genomic amplicons of dihydroflavonol 4-reductase (DFR) and anthocyanidin synthase (ANS). The B and C loci were linked to SSRs on chromosomes 1 and 6 respectively. For all of three families, SNPs in DFR cosegregated with the R locus conditioning red bulb color. In the family from B2246 × B11159, red bulbs versus yellow bulbs were controlled by DFR and a locus (L2) linked at 6.3 cM to ANS. The authors propose that yellow bulb onions have been independently selected numerous times and that yellow populations carry independent mutations in structural or regulatory genes controlling the production of red bulb color in onion.