CHLOROPLAST DNA PHYLOGENY OF OLD-WORLD VIGNA (LEGUMINOSAE)

As presently circumscribed, the genus Vigna contains approximately 150 species distributed in both the New World and Old World. The objective of our work was to test Old World Vigna for monophyly and to study infrageneric relationships. A total of 72 chloroplast DNA mutations was scored among 27 Vigna species, representing six of the seven subgenera and 11 of the 13 Old World sections. Cladistic analysis of these data supports the monophyly of Old World Vigna, the only exception being V. frutescens or subg. Vigna, which fell within the New World Vigna clade. Subgenus Haydonia occupies a basal position in the Old World Vigna clade and is paraphyletic. Subgenus Vigna is polyphyletic. Four Old World cpDNA clades are well resolved: 1) sects. Catiang (the cowpea section) and Reticulatae of subg. Vigna together with subg. Plectotropis; 2) subg. Ceratotropis (the Asian beans); 3) sect. Vigna of subg. Vigna; and 4) sect. Macrodontae of subg. Vigna. The cpDNA phylogeny of Old World Vigna is generally consistent with previous studies. CpDNA results suggest that sects. Catiang and Reticulatae could be split from subg. Vigna and placed with subg. Plectotropis.