Smallest Angiosperm Genomes Found in Lentibulariaceae, with Chromosomes of Bacterial Size

Abstract

Nuclear holoploid genome sizes (C-values) have been estimated to vary about 800-fold in angiosperms, with the smallest established 1C-value of 157 Mbp recorded in Arabidopsis thaliana. In the highly specialized carnivorous family Lentibulariaceae now three taxa have been found that exhibit significantly lower values: Genlisea margaretae with 63 Mbp, G. aurea with 64 Mbp, and Utricularia gibba with 88 Mbp. The smallest mitotic anaphase chromatids in G. aurea have 2.1 Mbp and are thus of bacterial size (NB: E. coli has ca. 4 Mbp). Several Utricularia species range somewhat lower than A. thaliana or are similar in genome size. The highest 1C-value known from species of Lentibulariaceae was found in Genlisea hispidula with 1510 Mbp, and results in about 24-fold variation for Genlisea and the Lentibulariaceae. Taking into account these new measurements, genome size variation in angiosperms is now almost 2000-fold. Genlisea and Utricularia are plants with terminal positions in the phylogeny of the eudicots, so that the findings are relevant for the understanding of genome miniaturization. Moreover, the Genlisea-Utricularia clade exhibits one of the highest mutational rates in several genomic regions in angiosperms, what may be linked to specialized patterns of genome evolution. Ultrasmall genomes have not been found in Pinguicula, which is the sister group of the Genlisea-Utricularia clade, and which does not show accelerated mutational rates. C-values in Pinguicula varied only 1.7-fold from 487 to 829 Mbp.

Genome size variation in Chenopodium quinoa (Chenopodiaceae)

“…to 152.23 pg/1C in Paris japonica Franch. (Greilhuber et al 2006;Pellicer et al 2010). Interest in the genome size has been fuelled by the fact that nuclear DNA content can affect various characteristics at the cellular, tissue and organism levels, and can have important ecological and evolutionary consequences (Knight et al 2005).…”

Evolution of genome size and genomic GC content in carnivorous holokinetics (Droseraceae)

“…250 existing Droseraceae species (Rothfels and Heimburg, 1968;Vesel y et al, 2012;Jensen et al, 2015). The reported genome sizes (2C ¼ 587 Mbp in Drosera capensis to 2C ¼ 5912 Mbp in Dionaea muscipula) seem to be generally larger than in Lentibulariaceae (2C ¼ 126 Mbp in Genlisea aurea to 2C ¼ 3020 Mbp in Genlisea hispidula; Greilhuber et al, 2006) but still relatively small compared with genome sizes known in other angiosperms (Bennett and Leitch, 2012). Given the small number of analysed species and other characteristics noted below, it cannot be excluded that this family may still hide species with similarly miniaturized genomes as in the carnivorous family Lentibulariaceae.…”

“…) on the outcomes of molecular processes (retrotransposon amplification, polyploidy), which vary in their degree across various angiosperm clades (Wendel et al, 2013). The smallest angiosperm genomes are known from the carnivorous family Lentibulariaceae (Greilhuber et al, 2006;Fleischmann et al, 2014;Veleba et al, 2014), making these miniature carnivorous species excellent candidates for whole-genome sequencing.…”

Genome size variation and polyploidy incidence in the alpine flora from Spain

“…Still, the available data for approximately 7500 species, already evidenced a large variation in genome size, spanning nearly a 2500-fold range, with Genlisea margaretae Hutch. (Lentibulariaceae, 1C = 0.06 pg; Greilhuber & al., 2006) and Paris japonica Franch. (Melanthiaceae, 1C = 152.20 pg; representing the smallest and the largest genomes discovered so far.…”