Development of a molecular cytogenetic system in carrot (Daucus carota L.) to study chromosome evolution in Daucus (Apiaceae family).

IOVENE, M.; CAVAGNARO, P. F.; SENALIK, D.; BUELL, R. C.; JIANG, J.; SIMON, P. W.

Conferencia; Plant and Animal Genomes XIX Conference; 2011

The genus Daucus (Apiaceae family) contains about 20 mostly diploid species, including carrot (D. carota L., 2n=18). It has been hypothesized that the basic chromosome number in the Apioideae is x=11 because this is the most common base number in this subfamily, although the current classification of Daucus is unresolved. While several projects have been initiated to enhance genetic analysis and breeding for carrot, very limited work has been done on the cytogenetic characterization of its genome. Here, we established a molecular cytogenetic system in carrot that can facilitate chromosome evolution studies in Daucus. First, we described a pachytene chromosome-based karyotype of carrot and integrated the carrot linkage groups with chromosomes by FISH (fluorescent in situ hybridization) mapping genetically anchored BAC (bacterial artificial chromosome) clones. We also isolated a satellite repeat from the centromeric regions of the carrot chromosomes. Subsequently, the selected chromosome-specific BACs were FISH mapped in Daucus species with 2n=18 and 22. Most carrot BACs generated distinct FISH signals in these species, providing evidence for syntenic chromosome segments and rearrangements among them. The availability of interspecific hybrids between carrot and D. sahariensis (both 2n=18) enabled us to support the presence of a large pericentric inversion between these species and to suggest other potential rearrangements between them. These results provide a foundation for further cytogenetic characterization and chromosome evolution studies in Daucus.