Q. I have read that animals die of old age because telomeres, the protective caps at the ends of chromosomes, shorten, allowing harmful mutations to accumulate. Does the same mechanism apply to the life span of plants?
A. The theory that shortened telomeres limit the life span of animals, including humans, is widely studied, with more and more studies lending support. Whether this applies to plant life has long been controversial, but recent research suggests how it might work.
The life span of plants is highly variable; some trees, for example, achieve what looks like immortality in comparison with animals. One big difference in plants is that their growth areas, called meristems, appear to stay forever young and renewable.
Stem cells in meristems can develop in many ways and renew the plant’s parts as needed. A tree branch may die while a new shoot appears elsewhere. Roots continue to grow throughout the life of a plant.
Research published in the journal Cell Reports in 2015 found that in the meristems, telomere length was strongly associated with the ability to keep the genome stable and thus could be a key factor in longevity. Analyzing plant chemicals at the cellular level, the European researchers found that it was the stem cells themselves that had the longest telomeres and the most telomerase, the regulatory chemical they produce.