|Le Clerc, Valerie|
Submitted to: Journal of the American Society for Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/29/2001
Publication Date: N/A
Citation: Interpretive Summary: Plant breeders have found multiple uses for molecular DNA markers. One important use is for the characterization of genetic diversity, or overall variation in a species, since plant breeding relies upon the successful identification and manipulation of genetic variation. Carrot has been thought to be very diverse. Based on this study of 124 domesticated and wild carrot we confirmed this assumption and noted that carrot molecular markers are not very helpful in anticipating genetic traits which we are interested in. This information is useful for carrot researchers to understand the applicability of molecular markers in predicting traits we have seen in the field, like disease resistance.
Technical Abstract: In this study we examined a sample of 124 Daucus carota accessions, including cultivated carrot and related wild subspecies, using a variety of molecular markers. Represented within our sample were wild accessions from 18 different countries, 14 of 16 major root types of European origin, and examples of major North American and Asian cultivated carrot types. AFLP and iSSR markers revealed extensive variation within Daucus carota. Although cultivated carrot and wild Daucus carota subspecies can cross freely, cultivated and wild carrots clustered largely independently, supporting the possibility that human selection for desirable horticultural traits has artificially reduced gene flow between cultivated and wild forms. Our analyses support the likelihood that North American Daucus carota populations arose due to the introduction of weedy materials rather than the escape of cultivated forms. With the exception of wild vs. cultivated types, no genetic alliances were evident in dendrogram topology. Furthermore, between and even within unmapped marker classes, dendrogram topology predictions were not consistent. Generally poor correlations among root types, geographic origin, mitochondrial, plastid, and specific nuclear diversity and AFLP/iSSR data were also observed. We concluded that genetic diversity in carrot is extensive and relatively unstructured in nature.