DISTRIBUTION AND COMPLEX ORGANIZATION OF SATELLITE DNA-SEQUENCES IN AVENEAE SPECIES

Distribution, organization, and molecular analysis of four unrelated s atellite DNA components in Aveneae species are described. Highly repea ted DNA elements were cloned from Helictotrichon convolutum (CON1 and CON2) and Helictotrichon compressum (COM1 and COM2). The lengths of th e repeat monomers are 365 bp (CON1), 562 bp (CON2), 346 bp (COM1), and 476 bp (COM2). Similar repeats were detected by dot blots, Southern b lots, and by DNA sequencing in other species of the genus Helictotrich on, in Aveneae species, and in species of the tribes Andropogoneae and Oryzeae. All four satellite DNAs are differently distributed in the t axonomic groups mentioned above. Remarkably, the longer elements are b uilt up in a complex pattern of either shorter subrepeats arranged in tandem (COM2) or by duplications inserted into an original 369-bp elem ent (CON2). Shorter representatives, 190 bp, similar to CON1 elements occur in Holcus species. In Koeleria species, COM1-related repeats are only 180 bp in length. No similarity was found among the sequences CO N2, COM1, and COM2 or with sequences of other repetitive DNA elements of the grasses, but CON1 shows sequence similarity to an A genome spec ific repetitive DNA of Oryza (rice).