The longest-lived leaves of the plant kingdom can only be found in the harsh, extremely dry desert that crosses the border between southern Angola and northern Namibia.
The desert, of course, is not the most favorable place for living creatures to thrive, let alone lush greenery, but the Namib Desert, the oldest in the world, receiving parts of less than 2 inches of rain annually, is home to the plant genus known as velvichia.
In Afrikaans, the plant is called tweeblaarkanniedood, which means “two leaves that never die”. This is an apt name, as the wolvitch grows only two leaves, and grows continuously, in a life that can last for thousands of years.
“This plant can live for thousands of years and never stop growing. When it stops growing, it dies,” says Andrew Leach, a plant geneticist at Queen Mary University of London.
Some of the largest specimens of these plants are believed to be over 3,000 years old, with two leaves that have grown steadily since the beginning of the Iron Age, when the Phoenician alphabet was invented.
By some accounts, the fibrous leaves of Welwitschia, battered by dry desert winds and fed by thirsty animals, become torn and curled over time, giving the Welwitschia an octopus-like appearance.
Since its first discovery, velvichia has captured the attention of biologists including Charles Darwin and botanist Friedrich Welvichia, who named the plant after him. The burning ground and looking at it, he was afraid lest the touch prove that the plant is a figment of the imagination.
And in a study recently published in Nature Communications, researchers report some of the genetic secrets behind the wolvitch’s unique shape, long life and profound resilience.
“It gives us a basis for a better understanding of how velvicii does all the crazy things it does,” says Jim Lippens Mack, a plant biologist at the University of Georgia who was not involved in the study.
The genome of velvichia reflects the arid, nutrient-poor plant environment. Its genetic history appears to be consistent with its environmental history.
About 86 million years ago, after an error in cell division, the entire genome of the velvichia plant doubled during a period of increased aridity and prolonged drought in the region, possibly forming the Namib Desert itself, says Tao Wan, a botanist at the Fairy Lake Botanical Garden in Shenzhen, China. , the study’s lead author, added that “extreme stress” is often associated with genome duplication events.
Andrew Leach adds that duplicate genes are also released from their original functions, potentially taking on new ones. However, getting more genetic material has a cost, says Wan.
“The primary activity of life is DNA replication, so if you have a large genome, it really takes energy to sustain life, especially in such a harsh environment,” Wan explains.
To make matters worse, a large amount of the Velvetia genome are “non-significant” self-replicating DNA sequences called retrotransposons.
The researchers detected an “explosion” of retrotransposon activity 1 to 2 million years ago, likely due to increased temperature stress. But to counter this, the velvichia genome has undergone extensive genetic changes that silence unwanted DNA through a process called DNA methylation.
This process, along with other selective forces, has dramatically reduced the volume and cost of active maintenance of the Felvic Replication DNA library, says Wan, giving it “a cost-effective, efficient genome”.
The study also found that fulvicii has other genetic modifications hidden in its leaves.
The average leaves of a plant grow from the plant heads, or the tops of its stem and branches. But the original growth tip of the vulvichia dies, and the leaves instead flow from a weak area of the plant’s anatomy called the basal xylem, which supplies the plant with fresh cells, Wan says.
A large number of copies or increased activity of some genes involved in efficient metabolism, cell growth and stress resilience in this region may help this region continue to grow under severe environmental stress.
And in an increasingly warming world, the genetic lessons that velvicium must provide for humans may help breed crops that are tougher and less thirsty.
“When we see that the plant is able to live in this environment for a long time and preserve its DNA and proteins, I really feel that we can find hints on how to improve agriculture,” says Leibniz Mack.
Source: The Independent
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