The classification of carrot accession to either Western or
Eastern gene pool, done previously by Baranski et al. [24],
was based on the polymorphism of DNA simple sequence
repeat loci. For accessions with no molecular assessment
available, additional criteria were set to classify them to one
of these two types. As orange and white root color are characteristic
for Western carrot type, the presence of other color
and Asian origin was chosen as criteria to include an accession
to Eastern type. Thus Western and Eastern carrot types were
finally represented by 17 and 18 accessions, respectively
(Online Resource 1). It should be stressed that the lack of
clear delimitation between Eastern and Western types
depending on the country of carrot origin or root color is the
result of an intensive and long lasting breeding in which
materials of various origins were crossed. For example,
European materials were used to obtain cultivars in Japan
while Japanese cultivars were used as parental populations
in American breeding programs.