Nuclear DNA content variation within the genusTaraxacum (Asteraceae)

Nuclear DNA content was estimated using flow cytometry in 13 sections represented by 18 species of the genusTaraxacum using propidium iodide as the DNA stain. Investigated plants represented diploid, triploid and tetraploid species from sections considered both primitive and advanced, i.e.,T. sect.Dioszegia, Piesis, Glacialia, Mongolica, Scariosa, Obovata, T. pyrenaicum group,T. sect.Coronata, Palustria, Taraxacum (=Crocea),Kashmirana, Ruderalia andErythrosperma. Estimated nuclear 2C DNA content ranged from 1.74 pg in diploidT. linearisquameum (T. sect.Ruderalia) to 6.91 pg in tetraploidT. albidum (T. sect.Mongolica), demonstrating 3.97-fold variation. The lowest monoploid genome size 1C_x=0.87 pg was recorded inT. linearisquameum (T. sect.Ruderalia) together withT. brachyglossum (T. sect.Erythrosperma), and the highest one (1.73 pg) was recorded inT. albidum (T. sect.Mongolica), giving a 1.99-fold difference in the genus. No significant differences in genome size were observed withinT. sect.Ruderalia, similarly no intraspecific variation was observed inT. paludosum (T. sect.Palustria) andT. serotinum (T. sect.Dioszegia). These results indicate a high intraspecific stability of the trait. Preliminary comparisons of genome size in species/sections considered to be close relatives were made. These data give tentative additional evidence for the close phylogenetic relationship between sectionsPalustria andPiesis and against the close relationship between sectionsPiesis andDioszegia.