Genetic Mapping of Chartreuse Bulb Color in Onion

Abstract

The most common bulb colors of onion (Allium cepa) are red, yellow, and white; chartreuse is a relatively rare bulb color conditioned by the homozygous recessive genotype at the G locus. In this research, plants with chartreuse bulbs were crossed with inbreds with yellow bulbs to develop segregating families for genetic mapping of the G locus. For all of 17 F2 families, segregations for yellow vs. chartreuse bulbs fit the expected 3:1 ratio (P > 0.05). DNAs were isolated from one F2 family and genotyped for single nucleotide polymorphisms (SNPs) to produce a genetic map of the G locus and 380 SNPs, of which 119 SNPs have not been previously mapped. Segregations for yellow vs. chartreuse bulbs placed the G locus at the end of chromosome 7 at 6.7 cM from the nearest SNP (isotig28625_2789). This codominant SNP marker linked to the G locus should be useful for introgression of recessive chartreuse bulb color into diverse onion populations for commercial production of this uniquely colored onion.