Article

Based on literature survey, chromosome numbers for 12 Gagea sections and 97 accepted species (for a total of 270 accessions) were obtained. Early branching lineages are all composed by diploids, while the widest range of ploidy level variation occurs in species-rich sections Gagea and Didymobulbos. Data on basic chromosome number, ploidy level, chromosome total haploid length (THL) and measures of karyotype asymmetry (calculated for 8 Gagea sections, 42 species and a total of 60 accessions) were included in a data set. Combining the large amount of data enabled mean karyotypes to be produced, highlighting differences in karyotype structure between sections. Further differences were noted when parameters for analysing karyotype asymmetry were assessed and superimposed onto a phylogenetic framework. DA recognized correctly the 8 considered sections in 100% of cases, and the same happened within section Gagea (series Solenarium, Gagea, Helenaeanae and Monticolae) and within section Didymobulbos (series Saxatiles, Occidentales, Arvenses and Chrysanthae). Despite massive genome size reduction is a noticeable feature of Gagea respect to other Lilioideae taxa, also in this genus there is a slight tendency to increase again the chromosome size, especially in late branching sections (e.g. Bulbiferae, Platyspermum, Minimae, Didymobulbos). Hence, the relatively high CVCL values occurring in Gagea sections (except the early branching sect. Anthericoides) seemingly originated through chromosome rearrangements towards a bimodal karyotype, without significant genome size variation.