Ginkgo Biloba Lives Long as if Nearly Immortals! 

Humans may not live for a thousand years, but some trees can. For example, the Ginkgo biloba tree. It can exceed its life span to more than 3000 years! Scientists have come forward to reveal the mystery of the unusual yet spectacular long-life duration of the Ginkgo biloba trees. With their latest and comprehensive research on plant aging, they came to the decision that the mystery is “molecular mechanisms.” This mechanism allows the Ginko Biloba and other trees to have a long life.  

Scientists always suspected something that is related to the first real genetic evidence. According to the biologist from Aberystwyth University- “The default condition in plants is immortality.” He says this but he was not a part of the research. 

As excising the cores of trees do not harm them, scientists started to work on this bold claim. They took 34 G. Biloba trees as a research subject. The trees they chose were from Anlu, in China’s Hubei province, and Pizhou, in Jiangsu province. Li Wang and his colleagues work at Yangzhou University as molecular biologists. They finished his examination and found that instead of slowing down their growth rate even after hundreds of years, the ginkgos growth rate speeds up. The more interesting fact is that their photosynthetic ability, leaf size, and seed quality of the trees do not change as well in the long run. All these are vital indicators of health.  

How does the change happen at the genetic level? To answer the question, the researchers focused on the leaves’ and the cambium’ gene expression. Cambium is a thin layer of stem cells linking up the internal wood and external bark. It helps to differentiate into other tissues as long as the tree is alive. Wang’s team faced difficulty in finding out enough materials for their study as older trees contain fewer cambium layers. So, they completed a series of tests like hormone production, RNA sequencing, miRNA screening. They did the test on the trees ranging from 3 to 667 years. 

Senescence is the last and decaying stage of life in the trees. Researchers found expected results in the expression of genes related to senescence. The leaves die for this reason and there was no surprise in the case of Ginkgo trees. But when they turned towards the expression of those same genes in the cambium, they became astonished. There was no difference between young and old trees. So, although the leaves die, the tree remains strong even in the old age. The team reported this in the Proceedings of the National Academy of Sciences yesterday.  

In their long journey, the trees face some changes. In older trees the level of indole-3-acetic acid, a growth hormone decreases and the level of abscisic acid, a growth-inhibiting hormone increases. Researchers also found that the 200 years or older trees gene expression shows a decrease in cell division, differentiation, and expansion. It clarifies that the cambial cells are not similar to that of the younger trees. So, cambial stem cells do not increase by producing new wood and bark. 

Another author of the study is Jinxing Lin. He is working as a plant biologist at Beijing Forestry University. He opines that the division rate of cambial cells starts to decrease after a thousand-year and so the tree grows slowly. There are many instances of the Ginkgo trees accidental death because of pests or droughts.

Whether the trees become vulnerable to many threats and diseases in the older age is subject to concern for researchers. So, they start to examine the genes that resist pathogen and produce flavonoids, a protective antimicrobial compound. They confirm that they did not found any difference in gene expression and they can defend outside stressors. That’s a “striking” ability that helps the ginkgos grow healthily for thousands of years, says paper author and molecular biologist Richard Dixon of the University of North Texas, Denton.

Sergi Munné-Bosch of the University of Barcelona was not involved in the study. He says, “Not needing to worry about growing old is ‘something that for humans is difficult to understand.’ Aging is not a problem for this species. The most important problem that they have to deal with is stress.” 

Scientists are enthusiastic to continue the research further. By this, they will know the tree’s mutation rate and the mechanisms behind aging. Thomas and Munné-Bosch also have a prediction that the scientists will use the same method to find out the reasons for aging in other trees from short-lived to ancient ones.