Fluorescence in situ hybridization with multiple repeated DNA probes applied to the analysis of chromosomal and genomic relationship levels between faba bean (Vicia faba) and its close wild relatives

Abstract

The organisation of DNA sequences at chromosomal level in twelve Vicia species, more particularly among V. faba and its close wild relatives (V. narbonensis, V. hyaeniscyamus, V. johannis, V. galilaea, V. bithynica), has been performed using fl uorescence in situ hybridization (FISH). The four BamHI discrete size classes of 850, 900, 990 and 1750-bp of highly repetitive DNA isolated from V. faba, and the probes pTa 71 and pTa 794 containing the 18S-5.8S-26S rDNA and 5S rDNA, respectively, were used. The chromosomal location of the two ribosomal gene families distinguished V. faba from its close relatives. FISH to metaphase chromosomes in- dicates the presence of BamHI family sequences interspersed in both euchromatin and heterochromatin of the V. faba, V. narbonensis, V. hyaeniscyamus, V. galilaea, V. johannis and V. bithynica of taxonomic section Faba, and V. hybrida of section Hypechusa genomes; however, the level of hybridization clearly distinguished the V. faba genome from other species genomes. This analysis provides further evidence that V. faba should be considered as the most distinct. In the context of possible sources of germplasm for V. faba breeding, it is argued that none of the species can be considered as putative allies of faba bean. The repetitive sequences did not hybridize in situ with the chromosomal DNA of fiVicia species of section Vicia and section Cracca. The quantitative variation and/or complete absence of BamHI family repeats enabled differentiation among Vicia genomes.