Systematics/Phytogeography / Taxonomie/ Section
Joshi, Kunjani , Li, Jianhua .
Phylogenetics of Swertia L. (Gentianaceae- Swertiinae) and Molecular Differentiation of Swertia Species in Nepalese Medicinal Herbs.
Swertia consists of 150 species with a cosmopolitan geographic distribution and its center of species diversity in the Sino-Himalayan region. Recent phylogenetic studies indicate that Swertia is highly paraphyletic; S. dichotoma and S. tetraptera are more closely related to Halenia than to any other species of Swertia, which do not form a clade. We expanded taxon sampling from Nepal to further test the monophyly of Swertia as well as the naturalness of traditionally defined sections. Our data support the paraphyly of Swertia relative to other genera of Swertiinae, and highlight the need for reconsidering sections within Swertia. Section Ophelia is highly polyphyletic, while section Kingdon-Wardia may be derived from within the polyphyletic section Platynema. The results from internal transcribed spacer region of the nuclear ribosomal DNA are generally congruent with those of the chloroplast trnL-F sequences. However, there is one well-supported discrepancy between the two genomes. In the ITS tree, Swertia ciliata is positioned in the clade containing S. chirayita and S. lurida, while in the trnL-F tree, it is in the clade of S. dilatata, S. paniculata, S. pedicellata, and S. racemosa. This suggests that Swertia ciliata may have evolved from a hybridization event with S. dilatata, S. paniculata, S. pedicellata, or S. racemosa as the possible maternal parent. Both ITS and trnL-F data support the close relationship of Swertia lurida with S. chirayita. Swertia species, especially S. chirayita, have been used extensively in the Nepalese herbal medicine. We sampled multiple individuals from both field and local market in Nepal to find whether there are species-specific nucleotide changes. Our results indicate that each of the commonly used species has unique sequences and the ITS fragment can be used as a barcoding marker to differentiate plant sources of Swertia in the local medicinal market. KJ is a Fulbright Scholarship recipient.
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1 - Tribhuvan University, Department of Botany, Nepal
2 - Harvard University, Arnold Arboretum, Harvard University Herbaria, 22 Divinity Avenue, Cambridge, Massachusetts, 02138, USA
Presentation Type: Poster:Posters for Sections
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM