Molecular phylogeny of Daucus (Apiaceae)

We studied the phylogeny of 22 accessions of Daucus: D. broteri, D. capillifolius, D. carota, D. carota subsp. carota, D. carota subsp. commutatus, D. carota subsp. commutatus, D. carota subsp. drepanensis, D. carota subsp. gadecaei, D. carota subsp. gummifer, D. carota subsp. halophilius, D. carota subsp. hispidus, D. carota subsp. maritimus, D. carota subsp. maximus, D. carota var. boissieri, D. crinitus, D. glochidiatus, D. guttatus, D. involucratus, D. littoralis, D. muricatus, D. pusillus, and D. sahariensis, and seven accessions of related species based on prior hypotheses or our observations of phenetic similarity: Astrodaucus littoralis, Caucalis platycarpos, Margottia gummifera, Orlaya daucoides, Pseudorlaya pumila, Torilis sp., and Turgenia latifolia. We used DNA sequences from eight nuclear orthologs and one plastid region, the trnH-psbA intergenic spacer. The aligned data matrix was 7212 characters long and provided high bootstrap support for many clades. Orlaya daucoides was supported as the closest outgroup to Daucus. Concordant with prior molecular results Pseudorlaya pumila was imbedded within Daucus, as was Margottia gummifera, a new finding. All accessions of D. carota, D. sahariensis, and D. capillifolius (all 2n = 18) formed a clade with 100% bootstrap support, with all other species within the Daucus clade with chromosome numbers of = 20, 22, and 44 (D. glochidiatus). Sister to the D. carota clade was a clade containing Margottia gummifera and Pseudorlaya pumila, sister to these species was D. crinitus, sister to all the above was D. muricatus, and sister to all of the above was a clade containing the remaining Daucus species. Our research, and parallel morphological studies, highlight the difficult taxonomy of this group, and pointed out misidentifications in germplasm collections caused by similarity of many of these species and the lack of a reliable comprehensive taxonomic monograph of Daucus.