Plastome organization, genome-based phylogeny and evolution of plastid genes in Podophylloideae (Berberidaceae)

This study is the first to report whole-plastome sequence data for all 12 species of Podophylloideae (14 individuals) and a close relative, Achlys triphylla. These 15 plastomes proved highly similar in overall size (156,240–157,370 bp), structure, gene order and content, also when compared to other Ranunculales, but also revealed some structural variations caused by the expansion or contraction of the inverted repeats (IRs) into or out of adjacent single-copy regions. Our phylogenomic analysis, based on 63 plastome-derived protein-coding genes (CDS), supported the monophyly of Podophylloideae and its two major genera (EA: Dysosma, EA/ENA: Diphylleia), with Podophyllum peltatum L. (ENA) being more closely related to Diphylleia than to the group’s earliest diverging species, Sinopodophyllum hexandrum (EA). Furthermore, within this subfamily/dataset, matK was identified as the fastest evolving gene, which proved to be under positive selection especially in more recently derived, lower-elevation lineages of Dysosma, possibly reflecting an adaptive response to novel environmental (i.e. subtropical compared to higher-elevation/alpine) conditions. Finally, several highly variable noncoding regions were identified in the plastomes of Podophylloideae and Ranunculales. These highly variable loci should be the best choices for future phylogenetic, phylogeographic, and population-level genetic studies. Overall, our results demonstrate the power of plastid phylogenomics to improve p...
Source: Molecular Phylogenetics and Evolution - Category: Molecular Biology Source Type: research