the authors of The work, the Beijing Forestry University in China, have extracted a small cylinder from the trunk of the 34 specimens from healthy Ginkgo biloba living in the chinese provinces of Hubei and Pizhou, and have studied the inner rings, by observing that the trees have never stopped nor slowed down the growth over the years. And yet: not are even not changed significantly the size of the leaves, the ability to perform photosynthesis, and the quality of the seeds, all the elements generally considered to be indicators of the health state of a plant.
To discover the underlying genetic mechanisms, the researchers then compared the expression of genes in leaves and in the so-called exchange cribro-vascular, a thin layer of stem cells placed between the outer cortex and the exterior wood that differentiate into other tissues during the life of the tree. In particular, the scientists sequenced the Rna, investigated the production of hormones, and analyzed the micro-Rna, a series of molecules able to activate or deactivate the expression of specific genes in aged trees, very different, from 3 to 667 years. In this way, they discovered that, not surprisingly, the expression of genes associated with senescence increases significantly in the leaves; but also, and this is more surprising, that the same phenomenon does not occur in the transmission, where the expression of those genes is roughly the same both in young trees than in older ones. Which suggests that, although some of the 'organs' of the plant can grow old and die, it is very unlikely that the same happens to the tree as a whole.
This is not to say, however, that Gingko does not undergo any change with the passage of time: in the older trees have been observed to lower levels of a growth hormone, and, in contrast, higher levels of a hormone antagonistic to growth. "You can," said Jiaye Lin , one of the authors of the work, "that the growth of the tree slows down a bit after hundreds of years, and Gingko may actually die of old age. But it takes so much time that most of the trees actually die for 'accidents' or factors related to stress, such as pests or drought".
in Addition, scientists have also tried to understand if the resistance of trees to stress was somehow weakened by time, by examining the genes related to resistance to pathogens and the production of flavonoids, compounds protective antimicrobial. And also in this case, have not found significant differences in gene expression for trees of different ages, which helps the Gingko to grow in a healthy way for thousands of years. A little as if he never had to worry about getting old. Blessed are they.
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