Distribution and complex organization of satellite DNA sequences in Aveneae species

Abstract

Distribution, organization, and molecular analysis of four unrelated satellite DNA components in Aveneae species are described. Highly repeated DNA elements were cloned from Helictotrichon convolutum (CON1 and CON2) and Helictotrichon compressum (COM1 and COM2). The lengths of the repeat monomers are 365 bp (CON1), 562 bp (CON2), 346 bp (COM1), and 476 bp (COM2). Similar repeats were detected by dot blots, Southern blots, and by DNA sequencing in other species of the genus Helictotrichon, in Aveneae species, and in species of the tribes Andropogoneae and Oryzeae. All four satellite DNAs are differently distributed in the taxonomic groups mentioned above. Remarkably, the longer elements are built up in a complex pattern of either shorter subrepeats arranged in tandem (COM2) or by duplications inserted into an original 369-bp element (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 CON2, COM1, and COM2 or with sequences of other repetitive DNA elements of the grasses, but CON1 shows sequence similarity to an A genome specific repetitive DNA of Oryza (rice).

Diversity of a major repetitive DNA sequence in diploid and polyploid Triticeae

“…The molecular organization of pSc119.2 shows a trimer of 360 bp being defined by TaqI restriction sites and a monomer of 118 bp defined by HaeIII (Vershinin and Heslop-Harrison, 1998). A complex organization of satellite DNA sequences is similarly shown in other species of Triticeae (Anamthawat-Jó nsson and Heslop-Harrison, 1993) or Aveneae (Grebenstein et al, 1996). While in situ hybridization with pSc119.2 sequence identifies largely intercalary sites in wheat, mainly sub-terminal sites are detected in rye as the sequence family is part of the subtelomeric sequence blocks in rye (Cuadrado et al, 1995;Vershinin et al, 1995).…”

“…The in situ hybridization results also show weak hybridization along the length of chromosomes in most species. A complex organization of satellite DNA sequences involving recombination and amplification steps is also shown in different repetitive sequence families in other species of Triticeae (Anamthawat-Jó nsson and Heslop-Harrison, 1993) or Aveneae (Grebenstein et al, 1996).…”

Sequence homogenization and chromosomal localization of VicTR-B satellites differ between closely related Vicia species

“…However, some of the V. sativa sequences showed enhanced homogenization of dimer repeats, and the V. grandiflora V family clearly evolved a HOR structure with units originating from a pentamer sequence. The occurrence of HORs or monomers composed of tandemly repeated subunits has been reported for a number of satellites (Ugarkovic and Plohl 2002), including plant repeats TIII15 in V. faba (Nouzová et al 1999), COM2 in Aveneae species (Grebenstein et al 1996), or RAE730 in Rumex acetosa (Shibata et al 2000). Interestingly, the repeat length of subfamily V HORs (186 bp) falls within the range of 135-195 bp, which is most frequent in plant satDNAs (Macas et al 2002).…”

Centromere Satellites From Arabidopsis Populations: Maintenance of Conserved and Variable Domains

“…Many studies have compared the satellites from closely related species (Waye and Willard 1989;Grebenstein et al 1996;Alix et al 1998;Mestrovic et al 1998;Rajagopal et al 1999;Landais et al 2000;Nijman and Lenstra 2001). In these analyses, homogenization of satellite repeats within the genome has typically occurred, resulting in less variation within a species than between closely related species.…”