title: Breakdown of distyly in a tetraploid variety of Ophiorrhiza japonica (Rubiaceae) and its phylogenetic analysis.
abstract: We examined the floral morph of tetraploid Ophiorrhiza japonica Blume var. amamiana Hatus. and diploid O. japonica var. japonica to elucidate the association of distyly and ploidy levels. Chloroplast DNA phylogeny was reconstructed to determine the number of tetraploidization events and floral morph shifts in O. japonica. All individuals of O. japonica var. amamiana proved to be long-homostylous, whereas O. japonica var. japonica was distylous with typical long- and short-styled flowers. Distyly is related to the ploidy level. The bagging treatment of flowers indicated that O. japonica var. amamiana is self-compatible and potentially automatically self-pollinating. In cpDNA sequencing analysis, no haplotype was shared between the two varieties. The cpDNA haplotype network displayed the monophyly of O. japonica var. amamiana, suggesting a single origin of this variety. Hence, both tetraploidization and the breakdown of distyly to homostyly in O. japonica var. amamiana likely occurred just once. Because O. japonica var. amamiana having the morphological and cytological entity is recognized as a single lineage and clearly separated from O. japonica var. japonica, this variety can be considered to be a distinct species. We therefore propose to raise O. japonica var. amamiana to the rank of species.
authors.affiliation: Graduate School of Engineering and Science, University of the Ryukyus, Senbaru 1, Nishihara, Okinawa, 903-0213, Japan. k048569@eve.u-ryukyu.ac.jp
authors.forename: Koh
authors.initials: K
authors.lastname: Nakamura
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Denda
authors.forename: Osamu
authors.initials: O
authors.lastname: Kameshima
authors.forename: Masatsugu
authors.initials: M
authors.lastname: Yokota
mesh_terms: D001483:Base Sequence; D017931:DNA Primers; D008855:Microscopy, Electron, Scanning; D010802:Phylogeny; D011123:Polyploidy; D019666:Rubiaceae / Q000145:classification / Q000235:genetics*
chemical_list: D017931:DNA Primers