Evolutionary dynamics of genome size in a radiation of woody plants

Abstract

PREMISE Plant genome size ranges widely, providing many opportunities to examine how genome size variation affects plant form and function. We analyzed trends in chromosome number, genome size, and leaf traits for the woody angiosperm clade Viburnum to examine the evolutionary associations, functional implications, and possible drivers of genome size. METHODS Chromosome counts and genome size estimates were mapped onto a Viburnum phylogeny to infer the location and frequency of polyploidization events and trends in genome size evolution. Genome size was analyzed with leaf anatomical and physiological data to evaluate the influence of genome size on plant function. RESULTS We discovered nine independent polyploidization events, two reductions in base chromosome number, and substantial variation in genome size with a slight trend toward genome size reduction in polyploids. We did not find strong relationships between genome size and the functional and morphological traits that have been highlighted at broader phylogenetic scales. CONCLUSIONS Polyploidization events were sometimes associated with rapid radiations, demonstrating that polyploid lineages can be highly successful. Relationships between genome size and plant physiological function observed at broad phylogenetic scales may be largely irrelevant to the evolutionary dynamics of genome size at smaller scales. The view that plants readily tolerate changes in ploidy and genome size, and often do so, appears to apply to Viburnum.

Tracing the Evolution of the Angiosperm Genome from the Cytogenetic Point of View

“…Recently, these results were supported by Carta et al [ 71 ], who modelled the evolution of the haploid chromosome number in angiosperms based on the data that is available in the Chromosome Count Data Base [ 59 ]. Similar values of the ancestral state of the chromosome number have also been inferred for several families in the angiosperms, for example, the basic chromosome number x = 10 was revealed for Eleusininae [ 72 ], x = 9 for Melanthiaceae, Asteraceae [ 30 , 73 , 74 ] and x = 7 for Brassicaceae [ 34 ]. Some other families have an ancestral chromosome number that seems to be the duplicate of a number of the angiosperm ancestral state such as Araceae ( n = 16 or n = 18 [ 75 ] or Arecaceae ( n = 16; [ 76 ]).…”

Reconstructing Dipsacales phylogeny using Angiosperms353: issues and insights

“…However, although many paralogs were recovered in Acanthocalyx , Cryptothladia , and Morina , these paralogs most often formed lineage specific clades that appear to conflict with the hypothesis of a shared Morinoideae duplication event. Duplication events are common within Dipsacales; for example, genome size has been dynamic in Viburnum , with multiple duplication and some evidence of subsequent downsizing (Moeglein et al, 2020). It is also noteworthy that, while plastid and some nuclear data suggest that Zabelia is sister to Morinoideae, Zabelia does not share this increase in base chromosome number, and instead has x = 8–9 (Kim et al, 2001), as is found throughout Linnaeeae (Sax and Kribs, 1930; Zhang et al, 2002).…”

De novo genome assembly of the medicinal plant Gentiana macrophylla provides insights into the genomic evolution and biosynthesis of iridoids

“… 12–15 The genome size variation of plant species is related to the chromosome number changes caused by whole-genome duplication (WGD), hybridization, and chromosome loss. 16 It has been shown that adaptive radiation as well as introgression and polyploidization events have contributed considerably to the species richness in the genus Gentiana . 17–19 Therefore, WGD and/or hybridization had a profound impact on the evolution of Gentiana species facilitating diversifications of phenotypes and secondary metabolites via gene divergence and structural variants.…”