Comparison of Molecular Cytogenetic and Genetic Analyses in Accessions of the Two Biotypes of Vicia benghalensis L.

InVicia benghalensis two different biotypes, named A and B,had been observed which differed for several cytological, geneticaland biochemical characters. In the present study 27 accessionsof this species belonging to the two biotypes were investigatedusing different molecular analyses, supported by an attemptto produce hybrids between selected accessions. RAPD fingerprintingof the 27 accessions demonstrated that accessions belongingto biotype A show a high degree of genetic similarity, whilethe opposite is true for the accessions of biotype B. The totalgenomic DNA from one reference accession was used as a probeto Southern blots of the DNA extracted from all the accessionsin use. This analysis demonstrated that cross hybridizationamong the DNA of the two biotypes occurs only to a limited extent.The chromosomal localization of 18S-5.8S-25S and 5S rRNA geneclusters was determined byin situ hybridization. The resultsindicate that the two biotypes differ in the position of oneof the 5S rRNA gene clusters. This indicates a major chromosomalrearrangement. Cell synchronization experiments on two referenceaccessions suggested that the two biotypes might differ in theduration of the single phases of the cell cycle. Finally, incrossing experiments three pods were obtained which developedfor only a few days and proved to bear no viable seeds. Theseresults confirm the existence of two divergent gene-pools anddemonstrate the reproductive barrier between the two biotypes,thus suggesting the possibility of a specific ranking. Vicia benghalensis L.; genetic differentiation; in situ hybridization; Southern hybridization; crosses; RAPDs; cell synchronization