Abstract
Shima-ninjin is a carrot with a long yellow root. The spread of orange root contaminants is a serious issue for shima-ninjin cultivation. In carrots, root color is regulated by the Y, Y2 and Or genes, and the genotypes of the yellow color have been reported to be yyY2_ or a homozygote of wild type Or allele with yyy2y2. In other words, by identifying the genotype of the Y2 locus, the genetic mechanism of the yellow color in shima-ninjin could be estimated. Therefore, as a first step to clarifying the genetic basis of the yellow color in shima-ninjin, genotyping of the Y2 locus was carried out. An investigation for each four yellow shima-ninjin and orange contaminants using the 4144ApeKI CAPS marker and genotyping of 186 germplasm, 166 shima-ninjin and 20 orange contaminants, with the newly developed 4144BssSI CAPS marker showed that the recessive y2 and SY2 designated in this study were existed. Furthermore, the homozygotes of SY2 showing orange root color suggested that SY2 is also recessive allele and Or gene may be involved in yellow color. To confirm the involvement of the Or gene and produce seeds without contaminants, an association analysis was carried out in F1 progeny. All fifty F1 progeny, the homozygotes of the well-known recessive y2, had the yellow root. These results suggest that the yellow phenotype in shima-ninjin may be determined by the Or as well as the Y and Y2 genes and traditional yellow shima-ninjin seeds without contaminants are producible.
