Comparative molecular cytogenetic characterization of five wild species (Fabaceae).

To extend our knowledge on karyotype variation of the genus Savi, 1824, the chromosomal organization of rRNA genes and fluorochrome banding patterns of five wild species were studied. Sequential combined PI (propidium iodide) and DAPI (4',6-diamidino-2-phenylindole) (CPD) staining and fluorescence hybridization (FISH) with 5S and 45S rDNA probes were used to analyze the karyotypes of (Jacquin, 1771) Bentham, 1959, (Linnaeus, 1753) A. Richard, 1845, (Roxburgh, 1832) Ohwi & H. Ohashi, 1969, (Linnaeus, 1753) Verdcourt, 1968, and (Linnaeus, 1753) Verdcourt,1970. For further phylogenetic analysis, genomic hybridization (GISH) with the genomic DNA of (Thunberg, 1794) Ohwi & H.Ohashi, 1969 onto the chromosomes of five wild species was also performed. Detailed karyotypes were established for the first time using chromosome measurements, fluorochrome bands, and rDNA-FISH signals. All species had chromosome number 2n = 2x = 22, and symmetrical karyotypes that composed of only metacentric or metacentric and submetacentric chromosomes. CPD staining revealed all 45S rDNA sites in the five species analyzed, (peri)centromeric GC-rich heterochromatin in , and , interstitial GC-rich and pericentromeric AT-rich heterochromatin in . rDNA-FISH revealed two 5S loci in and one 5S locus in the other four species; one 45S locus in and , two 45S loci in and , and five 45S loci in . The karyotypes of the studied species could be clearly distinguished by the karyotypic parameters, and the patterns of the fluorochrome bands and the rDNA sites, which revealed high interspecific variation among the five species. The genomic DNA probe produced weak signals in all proximal regions of and all (peri)centromeric regions of . The combined data demonstrate that distinct genome differentiation has occurred among the five species during evolution. The phylogenetic relationships between the five wild species and related cultivated species of are discussed based on our present and previous molecular cytogenetic data.