Springer Science+Business Media, LLC 2012. Most plant chromosomes terminate in an array of 7-bp DNA repeats (TTTAGGG). DNA-binding proteins associate with this repeat to form a protective nucleoprotein cap termed the telomere, an essential role of which is to prevent chromosome ends from being joined by double-strand break-repair mechanisms. The telomere repeat array (TRA) is highly dynamic. It is extended by telomerase, an enzyme that synthesizes additional telomere repeats, and it is shortened by incomplete replication during S phase, recombination, and other factors. From the starting point of the mammalian model of telomere structure, several proteins that may interact with telomeric DNA and that are important for forming a functional telomere have been identified in plants. Also, additional components of the Arabidopsis telomerase holoenzyme have been found. In many species, arrays of longer satellite sequences are located adjacent to the TRAs, and such arrays have been used as cytological tools to identify chromosomes in several grass species. Transgenic introduction of TRAs can lead to formation of a functional telomere and loss of the distal chromosomal segment. This technology has the potential to allow manipulation of plant chromosomes.
