ANALYSIS OF TELOMERE LENGTHS IN APPLE AND CHERRY TREES

Abstract

Telomeres are specialized nucleoprotein structures located at the ends of linear eukaryotic chromosomes. Because telomeres shorten with successive cell divisions in normal human somatic cells cultured in vitro, telomere length can be regarded as a mitotic clock that counts the total number of cell divisions that cells have undergone. Therefore, we focused on telomere lengths of fruit trees with respect to their life span, aging, and juvenility. To investigate the effects of long periods of cell division on telomere length, the lengths of telomeres in apple and cherry trees of the Rosaceae were measured. Telomere lengths were compared in suckers and upper branches. No significant difference in telomere length was observed in cells from different parts of the trees, indicating that the telomere lengths did not change at least for five years in the apple trees, or for twenty years in the cherry trees. Differences in telomere lengths were not observed between tissues in the juvenile and adult phases, either. Therefore, telomere lengths in Rosaceae trees do not change over the course of long periods of cell divisions; this is unlike the situation in humans. Long life spans of fruit trees may be related to the maintenance of stable telomere lengths. In F 1 seedlings of crosses of two apple cultivars, with different telomere lengths, the telomere lengths were found to segregate into various patterns, suggesting that the telomere lengths in apple are stably maintained by multigenes.