A NEW FAMILY OF DISPERSED REPEATS FROM BRASSICA-NIGRA - CHARACTERIZATION AND LOCALIZATION

The 459-bp HindIII (pBN-L4) and the 1732-bp EcoRI (pBNE8) fragments fr om the Brassica nigra genome were cloned and shown to be members of a dispersed repeat family. Of the three major diploid Brassica species, the repeat pBN-4 was found to be highly specific for the B. nigra geno me. The family also hybridized to Sinapis arvensis showing that B. nig ra had a closer relationship with the S. arvensis genome than with B. oleracea or B. campestris. The clone pBNE8 showed homology to a number of tRNA species indicating that this family of repeats may have origi nated from a tRNA sequence. The species-specific 459-bp repeat pBN4 wa s localized on the B. nigra chromosomes using monosomic addition lines . In addition to the localization of pBN-4, the chromosomal distributi on of two other species-specific repeats, pBN34 and pBNBH35 (reported earlier), was studied. The dispersed repeats pBN-4 and pBNBH35 were fo und to be present on all of the chromosomes, whereas the tandem repeat pBN34 was localized on two chromosomes.