Chloroplast DNA diversity in Vicia faba and its close wild relatives: implications for reassessment

Abstract

To obtain new information on phylogenetic relationships between wild and cultivated broad bean, restriction fragment length polymorphism (RFLP) analysis of chloroplast (cp) DNAs from Vicia faba and eight subspecies/species of its close wild relatives grouped together in the Narbonensis complex was carried out using 14 restriction endonucleases. The molecular sizes of the cpDNAs obtained were similar (122.6–123.4 kbp), indicating that they had all lost one of inverted repeats. Among the more than 300 sites surveyed, the three subspecies within V. narbonensis, which exhibit just as many types of karyotypes, were shown to have identical cp fragment patterns. Genetic distances between all of the pairs of species were calculated from RFLP data. The cpDNA diversity within the Narbonensis complex was found to be more extensive than expected, except for the genetic relationship between V. hyaeniscyamus and V. johannis in which a total of three mutations were detected among the 300 sites sampled, thereby showing their close relatedness. The cpDNA of V. faba vis-a-vis its wild relatives also exhibited startling differences, indicating a clear division of Vicia species into two distinct lineages. This analysis unambiguously provides new evidence that the wild species grouped in the complex did not contribute their plastomes to the evolution of V. faba, and hence none of the species can be considered to be putative allies of broad bean. The present study also demonstrates profound cpDNA diversity among closely related species that have lost one of inverted repeats.