Molecular phylogeny of Dioscorea (Dioscoreaceae) in East and Southeast Asia

K.-M Hsu,J.-L Tsai,H.-M Ku,M.-Y Chen,S.-C Liu

doi:10.3767/000651913x669022

Abstract

The phylogenetic relationships of Dioscorea, including sections Botryosicyos, Combilium, Enantiophyllum, Lasiophyton, Opsophyton, Shannicorea and Stenophora, are reconstructed with chloroplast trnL-F, matK, rbcL and atpB-rbcL sequence data, covering a total of 72 accessions including 48 ingroup species and five outgroup species from East and Southeast Asia. The seven Asian sections do reflect the genetic relationships among the species that they include. In summary, D. sect. Combilium and sect. Shannicorea are recognized as closely related sections with moderate support. The results also support Burkills treatment of subsect. Euopsophyton (D. bulbifera) as sect. Opsophyton and subsect. Macrourae (D. sansibarensis) as sect. Macroura. In addition, there is a well-supported sister relationship between D. sect. Lasiophyton and sect. Botryosicyos. The level of morphological characters and molecular divergence within D. sect. Enantiophyllum is low, but the members of this group could still be distinguished from each other.

Highlights

Dioscorea L. is the largest genus of Dioscoreaceae with about 600 species distributed in Southeast Asia, Africa, Central America, South America and other tropical and subtropical regions (Huber 1998)
PCR reactions were performed in a PCR thermocycler (GeneA mp 9700 PCR system; Applied Biosystems, Foster City, CA, USA) and carried out in the following conditions: an initial denaturation step at 94 °C for 5 min, followed by 35 cycles of 94 °C for 1 min, 52 °C for 1 min and 72 °C for 2 mins, with a final extension of 72 °C for 7 min
Systematic implications of the molecular phylogeny. Based on their twining stems, compound leaves, underground organ morphology, hairs, male flowers, capsule and seed characters, the species of Asian Dioscorea can be divided into nine sections

Summary

Introduction

Dioscorea L. is the largest genus of Dioscoreaceae with about 600 species distributed in Southeast Asia, Africa, Central America, South America and other tropical and subtropical regions (Huber 1998). Dioscorea includes important vegetatively reproducing tuber crops, known as yams. Yams have played a significant role in the advent of agriculture in Southeast Asia including Taiwan (e.g., D. alata and D. esculenta) and equatorial Africa (e.g., D. cayenensis, D. dumetorum and D. rotundata) (Ayensu & Coursey 1972, Coursey 1981). Dioscorea species are used for food and pharmaceutical products. Species such as D. nipponica and D. zingiberensis contain diosgenin, which provides one of the important raw materials for the synthesis of steroid hormone drugs (Zhai et al 2009, Zhang et al 2010). It has been reported that D. bulbifera could be effective for curing thyroid diseases and cancer (Liu et al 2009)

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