First nuclear DNA C-values for 25 angiosperm families

DNA amount is a widely used biodiversity character. As known DNA C-values r epresent the global angiosperm flora poorly, better coverage of taxonomic g roups is needed, including at the familial level. A workshop, sponsored by Annals of Botany, was held at the Royal Botanic Gardens, Kew in 1997. Its k ey aim was to identify major gaps in our knowledge of plant DNA C-values an d recommend targets for new work to fill them by international collaboratio n. In 1997 C-values were known for approx. 150 families, meaning there was no estimate for most angiosperm families (approx 68 %). The workshop recomm ended a goal of complete familial representation by 2002, as a main target for angiosperms. Bennett et ai. (Annals of Botany 86: 859-909, 2000) presen ted a fifth supplementary list of angiosperm C-values from 70 original sour ces which included first C-values for 691 species. Only 12 (1.7 %) of these were first C-values for unrepresented families, so the need to improve fam ilial representation was substantially unmet. We began new work to address this in September 1999, and now report first DNA C-values for 25 angiosperm families. Such targeting seems essential to achieve the goal of familial c overage set by the 1997 workshop within 5 years. 4C values range from 0.67 pg (similar to Arabidopsis thaliana) in Amoreuxia wrightii (Cochlospermacea e) to 749 pg in Deutzia prunifolia (Hydrangeaceae). These data support the view that ancestral angiosperms almost certainly had small genomes (defined as 1C less than or equal to 3.5 pg). Chromosome counts are reported for 19 taxa, including first records for three genera plus four species. (C) 2001 Annals of Botany Company.