TITLE:
Molecular Phylogeny Determined Using Chloroplast DNA Inferred a New Phylogenetic Relationship of Rorippa aquatica (Eaton) EJ Palmer & Steyermark (Brassicaceae)—Lake Cress
AUTHORS:
Hokuto Nakayama, Kenji Fukushima, Tatsuya Fukuda, Jun Yokoyama, Seisuke Kimura
KEYWORDS:
Lake Cress; Neobeckia; Phylogeny; psbC-trnS; Rorippa; trnL Intron; trnG-trnM
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.5 No.1,
January
9,
2014
ABSTRACT: North American lake cress, Rorippa
aquatica (Eaton) EJ Palmer & Steyermark (Brassicaceae), is listed as an
endangered or threatened species. Lake cress shows heterophyllic changes in
leaf form in response to the surrounding environment. Therefore, this species
has received considerable attention from ecological and morphological
perspectives. However, its phylogenetic position and taxonomic status have long been a subject of debate. To analyze the phylogenetic relationship
of lake cress, we investigated chloroplast DNA sequences from 17 plant species.
The results of phylogenetic reconstruction performed using trnL intron, trnG (GCC)-trnM (CAU), and psbC-trnS (UGA) indicated
that lake cress is a member of Rorippa.
Moreover, we found that the chromosome number of lake cress is 2n = 30. This
result indicated that lake cress might have originated from aneuploidy of
triploid species or via intergeneric crossing. Taken together, our results
suggest an affinity between lake cress and Rorippa at the molecular level, indicating that lake cress should be treated as Rorippa aquatica (Eaton) EJ Palmer &
Steyermark.