CHARACTERIZATION OF A HIGHLY REPEATED DNA COMPONENT OF PERENNIAL OATS(HELICTOTRICHON, POACEAE) WITH SEQUENCE SIMILARITY TO A A-GENOME-SPECIFIC - SATELLITE DNA OF RICE (ORYZA)

The taxonomic relationships among perennial oats (Helictotrichon Besse r ex Schultes and Schultes, Aveninae, Aveneae, Poaceae) have been stud ied using highly repeated satellite DNA as a molecular marker. Highly repetitive sequences were isolated from restriction endonuclease diges ts of nuclear DNA of Helictotrichon convolutum, and satellite repeats (approximately 365 bp in length) were cloned, sequenced and compared a mong each other. They exhibited an intraspecific sequence variability of 6-9%. This satellite DNA, CON1, is differentially distributed withi n the genus Helictotrichon. In species of the subgenus Helictotrichon a high copy number is detectable, whereas in representatives of the su bgenera Pratavenastrum and Pubavenastrum the number of copies per geno me is rather low. Surprisingly, the satellite DNA repeat CON1 shows 74 % sequence similarity to an A-genome specific repetitive DNA of Oryza (rice).