First Nuclear DNA C-values for Another 25 Angiosperm Families

Abstract

Nuclear DNA C-value is an important genomic biodiversity character with many uses. An international workshop sponsored by Annals of Botany and held at the Royal Botanic Gardens, Kew, UK, in 1997 identified major gaps in our knowledge of plant DNA C-values and recommended targets for new work. Improved taxonomic coverage was highlighted as a key need for angiosperms, especially at the familial level. In 1997 C-values were known for only approx. 32% of angiosperm families; a goal of complete familial representation by 2002 was recommended. A review published in 2000 (Bennett et al.;Annals of Botany86: 859–909) noted poor progress towards this aim: of the 691 first C-values for species only 12 (1.7%) were for unrepresented families. We began new work to address this in 1999, reporting first DNA C-values for 25 angiosperm families in 2001 (Hanson et al.;Annals of Botany87: 251–258). Here we report first DNA C-values for a further 25 angiosperm families, increasing familial coverage in angiosperms to approx. 45%. Such targeting remains essential to approach the goal set by the 1997 workshop of familial coverage for angiosperms within 5 years. The 4C DNA amounts presented here range from 0.76pg (similar toArabidopsis thaliana ) in Roridula gorgonias(Roridulaceae) to 29.74pg in Gunnera manicata(Gunneraceae). 1C values were<3.5pg in 23 of the 25 families; these data provide further support for the view that ancestral angiosperms almost certainly had small genomes (defined as 1C⩽3.5pg). Chromosome counts are reported for 20 taxa, including first records for one genus and five species.