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

Abstract

Background and Aims Studies in the carnivorous family Lentibulariaceae in the last years resulted in the discovery of the smallest plant genomes and an unusual pattern of genomic GC content evolution. However, scarcity of genomic data in other carnivorous clades still prevents a generalization of the observed patterns. Here the aim was to fill this gap by mapping genome evolution in the second largest carnivorous family, Droseraceae, where this evolution may be affected by chromosomal holokinetism in Drosera.Methods The genome size and genomic GC content of 71 Droseraceae species were measured by flow cytometry. A dated phylogeny was constructed, and the evolution of both genomic parameters and their relationship to species climatic niches were tested using phylogeny-based statistics.Key Results The 2C genome size of Droseraceae varied between 488 and 10 927 Mbp, and the GC content ranged between 37Á1 and 44Á7 %. The genome sizes and genomic GC content of carnivorous and holocentric species did not differ from those of their non-carnivorous and monocentric relatives. The genomic GC content positively correlated with genome size and annual temperature fluctuations. The genome size and chromosome numbers were inversely correlated in the Australian clade of Drosera.Conclusions Our results indicate that neither carnivory (nutrient scarcity) nor the holokinetism have a prominent effect on size and DNA base composition of Droseraceae genomes. However, the holokinetic drive seems to affect karyotype evolution in one of the major clades of Drosera. Our survey confirmed that the evolution of GC content is tightly connected with the evolution of genome size and also with environmental conditions.

Diversity in genome size and GC content shows adaptive potential in orchids and is closely linked to partial endoreplication, plant life‐history traits and climatic conditions

“…Several case studies have documented GC content diversity in selected plant groups (e.g. geophytes – Veselý et al ., ; monocots – Šmarda et al ., ; the carnivorous plant families Droseraceae and Lentibulariaceae – Veleba et al ., , ), with c . 1000 records available to date, and more are emerging.…”

“…The ecological implications and adaptive potential of genome‐size variation are well documented, but little information is known about diversity in GC content. The only sporadic evidence available to date points to an association between GC content and climatic parameters, namely the increased ability of GC‐rich species to grow in regions with extremely cold winters or seasonal droughts (Šmarda et al ., ) and greater annual temperature fluctuations (Veleba et al ., ).…”

“…Genome size and GC content variation often exhibit strong phylogenetic dependence, which points to the need for using phylogeny‐corrected statistical models for unbiased data analysis (Šmarda et al ., ; Carta & Peruzzi, ; Veleba et al ., ). The recently published robust phylogeny of the orchid family, based on whole‐plastome sequencing (Givnish et al ., ), therefore removes the last obstacle to such a study.…”

Systematics of Drosera sect. Drosera s.s. (Droseraceae)

“…Using the topology of the trees obtained for the rbcL, postulated that the genus might have originated in southern Africa or in Australia, based on the current distribution of the extant species belonging to the species-poor lineages connected to deeper nodes (D. regia and D. arcturi, respectively). The genus, then, diverged into two lineages: the "Australian clade" and the "Cosmopolitan clade" Veleba et al, 2017). classification by Seine & Barthlott, 1994).…”

“…Droseraceae is a family of carnivorous herbs, comprised by three genera: the monospecific Aldrovanda (the water-wheel plant) and Dionaea (the Venus flytrap), and the species-rich Drosera (the sundews). The last is a worldwide-distributed genus, currently comprising around 250 species (Meimberg et al 2000 Previous phylogenetic studies based on combined data from morphology and/or different molecular markers (Williams et al 1994;Meimberg et al 2000Yesson & Culham 2005;Veleba et al 2017) support Drosera as a monophyletic group, sister to the clade including Dionaea and Aldrovanda. The South-African Drosera regia Stephens and the Australian-New Zealander D. arcturi Hook.…”