Searching for telomeric sequences in two Allium species

Some Alliaceae species have no tandemly repeated TTTAGGG sequences. Instead , at the very end of their chromosomes, there are highly repetitive satelli te and (or) rDNA sequences. These sequences apparently replace the canonica l plant telomeric sequences in these species. A method of preparing two-dim ensional surface spreads of plant synaptonemal complexes (SCs), combined wi th fluorescent in situ hybridization, has revealed that telomeric chromatin is tightly condensed at the ends of SCs in plants and animals. Using this method, we have tested the organization and location of those sequences pos tulated to cap the chromosomes in two species of the genus Allium: A. cepa and A. altaicum. We have also extended this study to other putative telomer e candidates, such as LTR (long terminal repeat) and non-LTR retrotransposo ns. None of the DNA sequences analyzed showed the characteristic telomeric organization at pachytene.