How the Ginkgo biloba achieves near-immortality

Amazing stuff! In brief, a Ginkgo biloba tree (tree of life) only dies if stress factors (e.g. pests, droughts) become to great to survive.

"As expected, the expression of genes associated with senescence, the final and fatal stage of life, increased predictably in dying leaves. But when researchers examined the expression of those same genes in the cambium, they found no difference between young and old trees. This suggests that although organs such as leaves perish, the trees themselves are unlikely to die of old age ... 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. ... To see whether the trees become more vulnerable to such stressors as they age, the researchers examined genes related to pathogen resistance and the production of protective antimicrobial compounds called flavonoids. They found no difference in gene expression for trees of different ages, suggesting the trees do not lose their ability to defend against outside stressors. "

"Ginkgo biloba trees that first sprouted as the Black Death ravaged Europe in the 1300s—and are still thriving—appear to have immune systems just as active as in trees only a couple of decades old. A new study, published yesterday (January 13) in PNAS, details how having an enduring defense system contributes to the tree’s seemingly ageless life."

"Comprehensive evaluation of the expression of genes related to autophagy, senescence, and age-related miRNAs, together with analysis of leaf photosynthetic efficiencies and seed germination rates, demonstrated that the old trees are still in a healthy, mature state, and senescence is not manifested at the whole-plant level."

How the Ginkgo biloba achieves near-immortality | Science | AAAS: Research reveals mechanisms that allow the tree to live thousands of years

Ginkgo's Extreme Longevity Credited to Immune System | The Scientist Magazine®: Genes related to the immune system stay active throughout the tree's life.

Multifeature analyses of vascular cambial cells reveal longevity mechanisms in old Ginkgo biloba trees | PNAS: There is considerable interest in how ancient trees maintain their longevity. Ginkgo biloba is the only living species in the division Ginkgophyta, and specimens can live for over 1,000 y. Here, we show that trees up to 600 y of age display similar leaf areas, leaf photosynthetic efficiencies, and seed germination rates. Transcriptomic analysis indicates that the vascular cambium of the oldest trees, although undergoing less xylem generation, exhibits no evidence of senescence; rather, extensive expression of genes associated with preformed and inducible defenses likely contributes to the remarkable longevity of this species. Aging is a universal property of multicellular organisms. Although some tree species can live for centuries or millennia, the molecular and metabolic mechanisms underlying their longevity are unclear. To address this, we investigated age-related changes in the vascular cambium from 15- to 667-y-old Ginkgo biloba trees. The ring width decreased sharply during the first 100 to 200 y, with only a slight change after 200 y of age, accompanied by decreasing numbers of cambial cell layers. In contrast, average basal area increment (BAI) continuously increased with