MOLECULAR RELATIONSHIP BETWEEN THE A-CHROMOSOME AND B-CHROMOSOME OF CREPIS-CAPILLARIS

The-molecular structure of the B chromosome of Crepis capillaris has b een analysed by DNA comparisons of plants with 2B and 0B chromosomes. No additional band, and no differences in the band intensity were dete cted in 2B plants after digestion with 18 restriction enzymes. One hun dred and five clones were obtained from 2B plants using the phenol-emu lsion reassociation technique in formamide (F-PERT). Only one (clone p Cc21) gave rise to additional hybridization bands in the DNA from 2B p lants, indicating that this sequence occurs both in A and B chromosome s. Clone pCc21 contains a 54-bp microsatellite sequence rich in CA din ucleotides, similar to those found in other eukaryotic genomes. We con clude that the B chromosome of C. capillaris carries no specific highl y repetitive sequence, but consists of sequences also present in the A chromosomes. The possibility remains that the heterochromatic pericen tromeric region of the B has a different organization with respect to standard heterochromatin.