Lack of isozyme similarity betweenVigna unguiculataand other species of subgenusVigna(Leguminosae)

摘要

The cowpea (Vigna unguiculata(L.) Walp.) is an important crop of tropical Africa, Asia, and South America. However, the relationship between the cowpea and other species of subg.Vignais relatively unknown. The objective of this study was to assess the genetic distance among species of subg.Vignausing isozymes. Twenty-four populations of the cowpea species and 39 populations from 10 other species (at least one species per section of subgenusVigna) were sampled. Nei's genetic distance was calculated from allelic frequencies at 26 isozyme loci. UPGMA cluster analysis was performed. The range of genetic distance among species of subg.Vigna(0.41 ndash; 2.69) was greater than previously reported in most plant genera. Three clusters of species were apparent. The first cluster included three species of sect.Vigna(V.luteola,V.oblongifolia, andV.subterranea(the Bambara groundnut)). The second cluster grouped together sectionsLiebrechtsiaandMacrodontae. The third cluster includedV.unguiculata,V.reticulata, andV.vexillata. The distances between species of this cluster were large and of similar size in all combinations (range from 0.92 to 0.95). None of the species included in this survey can be called a close relative ofV.unguiculata.Key words:Vigna, cowpea, isozymes, genetic distances.