A TY3/GYPSY RETROTRANSPOSON-LIKE SEQUENCE LOCALIZES TO THE CENTROMERIC REGIONS OF CEREAL CHROMOSOMES

¹ Institute of Plant Genetics and Crop Plant Research, D-06466 Gatersleben, Germany

² Genomics Institute, Jordan Hall, Clemson University, Clemson, SC 29670 USA

³ Institute of Cell Biology and Genetic Engineering, Natl. Acad. Sci., 252143 Kiev, Ukraine

⁴ Institute for Botany, University of Vienna, A-1030 Vienna, Austria

A 809 bp sequence homologous to the 745 bp centromeric sequence of sorghum (pSau 3A9, Jiang et al. 1996) was amplified from barley genomic DNA. It was localized by FISH to all centromeres of barley, wheat and rye chromosomes, revealed high similarity to the integrase region of Ty3/gypsy retrotransposons and served as a probe for isolating of a lambda clone (9) from a barley-derived library. This clone contained the coding regions for all five catalytic sites of the retrotransposon polyprotein flanked by two direct repeats homologous to the 'cereal centromeric sequence' (CCS1) of Aragon-Alcaide et al. (1996). Sequence analysis and FISH with various plasmid subclones of lambda clone 9 have shown the entire polyprotein and upstream flanking sequences to be present at barley centromeres. The preferential (or exclusive) localization of an apparently complete and evolutionarily conserved retroelement within the centromere of a cereal species is shown for the first time.