Isoenzyme diversity and phylogenetic affinities in Vicia subgenus Vicia (Fabaceae)

Abstract

Isoenzyme composition of ten enzymes and variability of their genetically heterologous isoenzymes (heterozymes) encoded by 17 loci has been studied with the use of polyacrylamide gel electrophoresis in 21 vetch species of the type subgenus of the genus Vicia in comparison with V. pisiformis of the subgenus Vicilla. In total, 118 electromorphs (putative allozymes) of different frequency and variability pattern within and between species were recorded. Cladistic analysis of the allozyme data revealed in the subgenus two basic monophyletic groups with two monophyletic subclades in both. One subclade of the first group includes species related to sections Vicia, Sepium, Pseudolathyrus and Lathyroides. The second subclade of the first group consists of species of the section Peregrinae. The species of the section Narbonensis, which are considered to be closest wild relatives of the cultivated faba bean by morphological similarities, form a subclade in a second monophyletic group, with V. hybrida, V. pannonica, V. anatolica, and V. melanops of the section Hyperchusa as a sister subclade. Vicia hyrcanica and V. lutea of the same section are placed on the cladogram as basally paraphyletic in the second monophyletic group. Vicia faba is placed either as basally paraphyletic to both monophyletic groups or in the Peregrinae subclade, depending on the use of evolutionarily less variable isoenzymes alone or together with polymorphic ones in the data matrixes. The placement of cultivated V. faba and its morphologically closest wild relatives of the section Narbonensis in different monophyletic clades on the allozyme phylograms shows that they belong to different phylogenetic branches within the subgenus and indicates more remote relationship between them than previously assumed from morphological similarity. UPGMA phenograms of Manhattan distances characterizing the extent of allozymic divergence between species are presented.