An isozyme-based assessment of the genetic variability within the Daucus carota complex (Apiaceae: Caucalideae)
Daucus carota sensu lato is a phenotypically variable Eurasian species complex that has been naturalized and cultivated worldwide. One hundred and sixty-eight accessions from 32 countries were surveyed by enzyme electrophoresis to determine the extent of genetic variation present in the species. Eight enzyme systems coded by 16 putative loci were surveyed. They indicate that the recognized subspecies have diverged only slightly from one another with respect to the enzymes surveyed. The samples of wild taxa are more genetically diverse than those of the cultivated taxa, but not significantly different with respect to the mean number of alleles per locus, the proportion of polymorphic loci, the observed and expected heterozygosities, or Nei's genetic diversity statistics (P > 0.05). Members of the aggregate group gingidium have significantly lower total gene diversity within a taxon (P <.05) than do members of the aggregate group carota, as well as lower gene diversity within populations of the taxa (P < 0.01). Thus allozyme divergence is concordant with morphological divergence. Cultivars with carotene-pigmented roots show negligible amounts of genetic divergence. They appear to have evolved in a simple pattern after an initial genetic bottleneck. Key words: Daucus carota, isozyme, electrophoresis, genetic variability.