Genome size in Anthurium evaluated in the context of karyotypes and phenotypes

BACKGROUND AND AIMS Anthurium is an important horticultural crop from the family Araceae, order Alismatales, a lineage considered to have diverged from other monocots prior to the cereals. Genome size and its distribution in Anthurium were investigated to gain a basic understanding of genome organization in this large genus and to forge a firm foundation for advancement of molecular approaches for the study of Anthurium. Currently, genome size estimates have been reported for only two Anthurium samples. METHODOLOGY Bulk nuclear DNA content estimates were obtained by flow cell cytometry using leaf tissue collected from Anthurium species of different subgeneric groups and from commercial cultivars. The most current and well-supported topology of subgeneric, sectional relationships was applied to present genome size estimates in the context of reported chromosome counts, karyotypes, putative phylogenetic relationships, observed phenotypes and pedigree. PRINCIPAL RESULTS Genome size estimates based on bulk nuclear DNA content for 77 accessions representing 34 species and 9 cultivars were obtained, including initial estimates for 33 Anthurium species, and both the smallest (Anthurium obtusum; Tetraspermium) and largest (Anthurium roseospadix; Calomystrium) Anthurium genome sizes reported to date. Genome size did not distinguish any subgeneric section, but ranged 5-fold (4.42-20.83 pg/2 C) despite consistent 2N= 30 chromosome counts. Intraspecies genome size variation >20 % is reported for Anthurium ravenii, A. watermaliense and A. gracile. CONCLUSIONS Genome size estimates for Anthurium species spanning 13 recognized subgeneric sections indicate that genome size does not generally correlate with chromosome count or phylogenetic relationships. Mechanisms of genome expansion and contraction, including amplification and reduction of repetitive elements, polyploidy, chromosome reorganization/loss, may be involved in genome evolution in Anthurium as in other species. The new information on Anthurium genome sizes provides a platform for molecular studies supporting further research on genome evolution as well as cultivar development.