Insights into the phylogeny and chloroplast genome evolution of Eriocaulon (Eriocaulaceae)

Abstract

AbstractBackgroundEriocaulonis a wetland plant genus with important ecological value, and one of the famous taxonomically challenging groups among angiosperms, mainly due to the high intraspecific diversity and low interspecific variation in the morphological characters of species within this genus. In this study, 22 samples representing 15Eriocaulonspecies from China, were sequenced and combined with published samples ofEriocaulonto test the phylogenetic resolution using the complete chloroplast genome. Furthermore, comparative analyses of the chloroplast genomes were performed to investigate the chloroplast genome evolution ofEriocaulon.ResultsThe 22Eriocaulonchloroplast genomes and the nine published samples were proved highly similar in genome size, gene content, and order. TheEriocaulonchloroplast genomes exhibited typical quadripartite structures with lengths from 150,222 bp to 151,584 bp. Comparative analyses revealed that four mutation hotspot regions (psbK-trnS,trnE-trnT,ndhF-rpl32, andycf1) could serve as effective molecular markers for further phylogenetic analyses and species identification ofEriocaulonspecies. Phylogenetic results supportedEriocaulonas a monophyletic group. The identified relationships supported the taxonomic treatment of sectionHeterochitonandLeucantherae, and the sectionHeterochitonwas the first divergent group. Phylogenetic tree supportedEriocaulonwas divided into five clades. The divergence times indicated that all the sections diverged in the later Miocene and most of the extantEriocaulonspecies diverged in the Quaternary. The phylogeny and divergence times supported rapid radiation occurred in the evolution history ofEriocaulon.ConclusionOur study mostly supported the taxonomic treatment at the section level forEriocaulonspecies in China and demonstrated the power of phylogenetic resolution using whole chloroplast genome sequences. Comparative analyses of theEriocaulonchloroplast genome developed molecular markers that can help us better identify and understand the evolutionary history ofEriocaulonspecies in the future.