Molecular phylogenetic study of the tribe Tropidieae (Orchidaceae, Epidendroideae) with taxonomic and evolutionary implications

Izai A B Sabino Kikuchi; Paul J A Keßler; André Schuiteman; Jin Murata; Tetsuo Ohi-Toma; Tomohisa Yukawa; Hirokazu Tsukaya

doi:10.3897/phytokeys.140.46842

Molecular phylogenetic study of the tribe Tropidieae (Orchidaceae, Epidendroideae) with taxonomic and evolutionary implications

PhytoKeys. 2020 Feb 19:140:11-22. doi: 10.3897/phytokeys.140.46842. eCollection 2020.

Authors

Izai A B Sabino Kikuchi¹, Paul J A Keßler¹, André Schuiteman², Jin Murata³, Tetsuo Ohi-Toma³, Tomohisa Yukawa⁴, Hirokazu Tsukaya^{5

6}

Affiliations

¹ Universiteit Leiden, Hortus botanicus Leiden, PO Box 9500, Leiden, 2300 RA, The Netherlands.
² Science Directorate, Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AB, UK.
³ Botanical Gardens, Graduate School of Science, The University of Tokyo, 3-7-1 Hakusan, Bunkyo-ku, Tokyo, 112-0001, Japan.
⁴ Tsukuba Botanical Garden, National Science Museum, 4-1-1 Amakubo, Tsukuba, 305-0005, Japan.
⁵ Department of Biological Sciences, Faculty of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
⁶ Bio-Next Project, Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Yamate Build. #3, 5-1, Higashiyama, Myodaiji, Okazaki, Aichi, 444-8787, Japan.

Abstract

The orchid tribe Tropidieae comprises three genera, Tropidia, Corymborkis and Kalimantanorchis. There are three fully mycoheterotrophic species within Tropidieae: Tropidia saprophytica, T. connata and Kalimantanorchis nagamasui. A previous phylogenetic study of K. nagamasui, based only on plastid matK data, placed K. nagamasui outside the clade of Tropidia and Corymborkis without support. In this study, we performed phylogenetic analyses using a nuclear ribosomal DNA spacer (ITS1-5.8S-ITS2), a low-copy nuclear coding gene (Xdh) and a mitochondrial intron (nad1b-c intron) to study the phylogenetic relationships within Tropidieae. We included six photosynthetic and all three fully mycoheterotrophic Tropidieae species. The resulting phylogenetic trees placed these fully mycoheterotrophic species inside the Tropidia clade with high support. In our trees, these three species do not form a monophyletic group together, because the photosynthetic T. graminea is nested amongst them. Our results also suggest that the loss of photosynthetic ability occurred at least twice in Tropidia.

Keywords: Corymborkis; Kalimantanorchis; Tropidia; mycoheterotrophy; phylogeny.

Izai A. B. Sabino Kikuchi, Paul J. A. Keβler, André Schuiteman, Jin Murata, Tetsuo Ohi-Toma, Tomohisa Yukawa, Hirokazu Tsukaya.