A CONSERVED REPETITIVE DNA ELEMENT LOCATED IN THE CENTROMERES OF CEREAL CHROMOSOMES

Repetitive DNA sequences have been demonstrated to play an important r ole for centromere function of eukaryotic chromosomes, including those from fission yeast, Drosophila melanogaster, and humans, Here we repo rt on the isolation of a repetitive DNA element located in the centrom eric regions of cereal chromosomes, A 745-bp repetitive DNA clone, pSa u3A9, was isolated from sorghum (Sorghum bicolor), This DNA element is located in the centromeric regions of all sorghum chromosomes, as dem onstrated by fluorescence in situ hybridization. Repetitive DNA sequen ces homologous to pSau3A9 also are present in the centromeric regions of chromosomes from other cereal species, including rice, maize, wheat , barley, rye, and oats, Probe pSau3AB also hybridized to the centrome ric region of B chromosomes from rye and maize, The repetitive nature and its conservation in distantly related plant species indicate that the pSau3A9 family may be associated with centromere function of cerea l chromosomes. The absence of DNA sequences homologous to pSau3A9 in d icot species suggests a faster divergence of centromere-related sequen ces compared with the telomere-related sequences in plants.