title: Phylogenetic Relationships of the Fern Cyrtomium falcatum (Dryopteridaceae) from Dokdo Island Based on Chloroplast Genome Sequencing.
abstract: Cyrtomium falcatumis a popular ornamental fern cultivated worldwide. Native to the Korean Peninsula, Japan, and Dokdo Island in the Sea of Japan, it is the only fern present on Dokdo Island. We isolated and characterized the chloroplast (cp) genome ofC. falcatum, and compared it with those of closely related species. The genestrnV-GACandtrnV-GAUwere found to be present within the cp genome ofC. falcatum, whereastrnP-GGGandrpl21were lacking. Moreover, cp genomes ofCyrtomium devexiscapulaeandAdiantum capillus-venerislacktrnP-GGGandrpl21, suggesting these are not conserved among angiosperm cp genomes. The deletion oftrnR-UCG,trnR-CCG, andtrnSeCin the cp genomes ofC. falcatumand other eupolypod ferns indicates these genes are restricted to tree ferns, non-core leptosporangiates, and basal ferns. TheC. falcatumcp genome also encodedndhFandrps7, with GUG start codons that were only conserved in polypod ferns, and it shares two significant inversions with other ferns, including a minor inversion of thetrnD-GUCregion and an approximate 3 kb inversion of thetrnG-trnTregion. Phylogenetic analyses showed thatEquisetumwas found to be a sister clade to Psilotales-Ophioglossales with a 100% bootstrap (BS) value. The sister relationship between Pteridaceae and eupolypods was also strongly supported by a 100% BS, but Bayesian molecular clock analyses suggested thatC. falcatumdiversified in the mid-Paleogene period (45.15 ± 4.93 million years ago) and might have moved from Eurasia to Dokdo Island.
authors.affiliation: Department of Life Sciences, Yeungnam University, Gyeongsan 38541, Korea. bioramg@gmail.com.
authors.forename: Gurusamy
authors.initials: G
authors.lastname: Raman
authors.affiliation: Department of Life Sciences, Yeungnam University, Gyeongsan 38541, Korea. kschoi01@ynu.ac.kr.
authors.forename: Kyoung Su
authors.initials: KS
authors.lastname: Choi
authors.affiliation: Department of Life Sciences, Yeungnam University, Gyeongsan 38541, Korea. sjpark01@ynu.ac.kr.
authors.forename: SeonJoo
authors.initials: S
authors.lastname: Park
keywords: Cyrtomium falcatum; chloroplast genome; holly fern; molecular clock; polypod ferns