The Ginkgo tree is known to be a very long-lived tree. Some have lived more than 2,500 years. A new study, published on Monday, shows that Ginkgo trees do not undergo senescence or the gradual deterioration of functional characteristics.
Researchers from China and the United States analyzed the RNA harvested from a Ginkgo biloba tree. The main goal of the study was to understand more about the tree’s longevity.
A team of researchers working in China collected samples of tissues from nine ginkgoes that are aged approximately 600, 200, and 20 years old.
In this study, unlike previous studies that focused on the leaves, the researchers were more interested in the cambium. Upon inspection of the tissue, the RNA analysis showed no sign of aging, however, they discovered that older Ginkgo biloba trees produce less of the common plant hormone auxin and produce more abscisic acid, the hormone produced to respond to stress. The older Ginkgo trees exhibited thinner annual rings and no differences in disease resistance and efficiency in photosynthesis and seed germination.
However, there is evidence that the trees do experience some changes over time. The older trees had lower levels of a growth hormone called indole-3-acetic acid and higher levels of a growth-inhibiting hormone called abscisic acid. Those 200 years or older also saw decreases in gene expression associated with cell division, differentiation, and expansion. This means that cambial stem cells in older trees don’t divide into new wood and bark as easily as in younger trees.
Plant biologist Jinxing Lin of Beijing Forestry University and an author of the study, says it’s possible that if the division rate of cambial cells continues to decline after thousands of years, tree growth could slow, and ginkgo trees might eventually die of old age. Most trees, however, appear to die from “accidents” such as pests or droughts.