DNA barcoding of Euphorbiaceae in Korea

Euphorbiaceae is one of the largest groups in the all Malpighiales families, consisting of approximately 6,500 species of four subfamilies (subfm. Euphorbioideae, subfm. Acalyphoideae Beilschm., Cheilosoideae K. Wurdack & Petra Hoffmann, and Crotonoideae Burmeist.) (Govaerts et al., 2000; APG IV, 2016). Members of Euphorbieae are monoecious or dioecious trees, shrubs, or herbs with milky latex, highly specialized inflorescence (cyanthium), superior and tri-locular ovary, and axile placentation (Park and Backlund, 2002; Thakur and Patil, 2011). The plants of this family are mainly distributed in the tropical and subtropical regions with some of native and naturalized species in the temperate regions including Asia, Australia, and North America (Heywood, 1985; Webster, 1986; 1994; Savolainen et al., 2000; Li et al., 2008; APG IV, 2016). A number of Euphorbiaceae species are economically and commercially important as food, ornamental, timber, or raw materials of wax, rubber, and dye (Salatino et al., 2007; Bennett, 2010; Kumar et al., 2010; Elhassan et al., 2015). In particular, many species in the genus Euphorbia are used as medicinal plants, although most of the plants in the genus contain toxic chemicals called diterpenoids (Hohmann and Molnár, 2004; Ernst et al., 2015). Since ancient times, various indigenous species are utilized as medicines for curing skin diseases, intestinal parasites gonorrhea, warts, and migraines on the basis of traditional folk recipes (Singla and Kamla, 1990; Salatino et al., 2007; Bennett, 2010; Kumar et al., 2010; Elhassan et al., 2015). For sustainable utilization of Euphorbiaceae as plant resources, accurate species identification and understanding of their phylogenetic relationships are essential steps (Pang et al., 2010; Aubriot et al., 2013). Although many previous phylogenetic studies were carried on with chloroplast (cp) DNA (atpB, matK, ndhF, rbcL, trnL-F) and/or nuclear (nr) DNA (ITS) loci (Wurdack et al., 2004; 2005; Tokuoka, 2007; Thakur and Patil, 2011; Yang et al., 2012; Aubriot et al., 2013; Riina et al., 2013), these studies only attempted to resolve higher level (family, genus or subgenus) relationships in Euphorbiaceae. Meanwhile, Pang et al. (2009) largely collected DNA sequences of two cpDNA (rbcL, matK) and two nrDNA (ITS1, ITS2) loci of the family Euphorbiaceae from GenBank and evaluated the species identification ability of four barcode loci. Among the four loci, Pang et al. (2009) reported the efficiency of the ITS1 and ITS2 loci for discrimination of species in the Euphorbiaceae famJournal of Species Research 9(4):413-426, 2020