Genome size variation and evolution in the family Asteraceae

The nuclear DNA content data available in A genome size database in the Asteraceae (GSAD: www.asteraceaegenomesize.com) have been analyzed, together with other parameters (i.e. ecological, karyological, cytogenetic), in order to establish hypotheses on the systematic, phylogenetic and evolutionary aspects of genome size in one of the largest angiosperm families. The novelty of this work is a comprehensive analysis of the whole family with the following aims: (1) to update the knowledge of genome size values in the Asteraceae; (2) to infer evolutionary trends of genome size, compared with other plant groups; and (3) to detect gaps in this field in the family and outline further research priorities. The analysis of this dataset shows that most Asteraceae genomes (57.23%) range from very small (1C <= 1.4 pg) to small (1C <= 3.5 pg). Gains and losses of DNA occur throughout the phylogeny of the family but although ancestral values for the basal nodes remain mostly equivocal, often small and very small ancestral genome sizes are reconstructed. Most genome size data (96.74%) are concentrated in five tribes, which broadly reflect their species richness. The relationships between genome size and other cytogenetic and ecological features have been analyzed and discussed, highlighting several general patterns. Further studies are needed to fill the gaps in genome size knowledge in the Asteraceae and more detailed research in some groups could provide information about mechanisms regulating genome expansions and contractions.