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Can you imagine a plant that existed before the dinosaurs became extinct and still exists in the world after a long history? This is the oldest plant in the world, the centenarian orchid. The oldest centenarian orchid is over 2000 years old.

Although its name is Welwitschia mirabilis, in fact it can not only live to be a hundred years old. Through carbon 14 dating, the researchers found that some centenarians are actually five or six hundred years old, while older orchids are likely to live to more than 2000-3, 000 years old.

At present, the oldest centenarian in the world is about 1500 years old. | there is a story hidden in the scientific name of Wiki Centennial Orchid. In the 19th century, Austrian botanist Frederich Welwitschia discovered a strange creature in Africa. It looks like an octopus growing in the desert, covered with curly and split leaves. The botanist was shocked, frightened, and even "could only kneel on the ground and do nothing, lest he touch it and find that the plant was a figment of imagination." After that, the scientific name of the hundred-year-old orchid was named after the botanist mirabilis, and the scientific name of the hundred-year-old orchid was miraculous, and the scientific name of the hundred-year-old orchid was "the magical plant discovered by Welwick": Welwitschia mirabilis.

The plant grows in the Namib Desert along the coasts of southern Africa, Angola and Namibia. The Namib Desert is one of the oldest deserts in the world and is a complete wasteland with less annual precipitation than 25mm. In order to survive in such a harsh environment, the hundred-year-old orchid has evolved a strange form: a short, stout inverted conical trunk, an extremely long main root used to absorb underground water, and, of course, the most important thing is that it has two leaves that will never fall off.

The structure of hundred-year-old orchids. | The Welwitschia genome reveals a unique biologyunderpinning extreme longevity in deserts in the South African language, centenarian orchid is also called "twee blaar kanniedood", meaning "two immortal leaves". Indeed, the centenarian orchid has only two leaves that can grow for thousands of years without falling off. Some people speculate that this is because tropical plants do not need to resist the cold by falling leaves like temperate plants, and there is no shortage of water all the year round. But how on earth does it absorb water in this arid and uninhabited desert?

Century orchid: not only is she not bald, but even her long hair is a little elegant. | Wiki centennial orchid has a well-developed root system, not only with deep underground access to groundwater, but also in this offshore desert, although the stomata on the leaf surface of Cymbidium cymbidium will be closed because of water saving, the fibrous roots near the ground will fully absorb the early morning sea fog to keep moist.

Not only the centenarian orchid, in fact, many plants growing in very arid areas in the world have their own water-saving skills-crassulacean acid metabolism (Crassulacean acid metabolism,CAM). In dry environments, plants undergoing CAM keep their leaf stomata closed during the day, reducing water evaporation, while at night, stomata open to absorb carbon dioxide, which is stored in vacuoles in the form of malic acid and converted back into carbon dioxide during the day for consumption by photosynthesis. Cactus and succulent plants growing in arid deserts all use this way to store water in their bodies. The reason why it is called "crassulaceae acid metabolism" is that this mechanism of acid metabolism was first discovered in Sedum plants.

In order to adapt to survival, succulent plants growing in tropical arid areas have developed a unique survival strategy: crassulose acid metabolism. | although the centenarian orchid looks like it has long bushy hair, it just looks like it has many, but in fact it only has two. | The meristem at the base of the leaf will continue to produce new leaf tissue to support its continuous growth. When the cells at the end of the leaf apoptosis, the tail of the leaf will gradually wither, showing the shape of being charred. But it still won't fall off, and this is actually one of the mysterious survival strategies of Centennial Orchid.

It really only has two leaves, it looks thick, maybe it's just because the leaves are too long. | Wiki, organized by the Sino-African Joint Research Center of the Chinese Academy of Sciences, Wantao researcher team of Xianhu Botanical Garden, Chinese Academy of Sciences, Wang Qingfeng, Wuhan Botanical Garden, Chinese Academy of Sciences, and scientists from Gobabeb Research Center of Namibia, Kew Royal Botanical Garden of the United Kingdom, Institute of Botany of Chinese Academy of Sciences, etc., started the research on Cymbidium, and explored its evolution history from the perspective of centenarian genome. And ecological adaptability.

Scientists have found that the genome of Cymbidium shows extremely severe methylation. The so-called gene methylation is to add methyl to the original DNA, which affects the expression of the gene, making it impossible for it to play the role that genetic material is supposed to have. To put it simply, it just doesn't let the original genes work properly.

The end of the leaf really has a charred shape. | Flickr@Tarmo Tamming methylation can maintain the integrity of the genome and avoid harmful mutations of DNA. In addition, heavy methylation accelerated the deamination of Cymbidium genome. Generally speaking, the cytosine (C) that makes up DNA is converted to uracil (U) after deamination, so the content of Gmurc in the cymbidium genome is abnormally low.

In the long process of development, the genome of Cymbidium has evolved in the direction of simpler and simpler and "low energy consumption".

This is because, for life, DNA replication is the most basic life activity. So having more genetic material means consuming a lot of energy. If centenarians want to survive in such a harsh environment as the desert, they need to find a low-cost energy consumption strategy.

Other genes have also undergone some changes, such as plant meristem-related cells, which allow two leaves of a hundred-year orchid to obtain newly differentiated leaf cells for thousands of years. In addition, its heat-resistant and highly lignified leaves can also adapt to extreme drought conditions.

And such a long-lived plant, which has gone through a long time and can endure extreme environments, is so unique that it belongs to the order Orchidaceae, Orchidaceae and Orchidaceae. In this large classification, there is only one seedling, the centenarian orchid. Perhaps when we see such a life that spans thousands of years, it will be as shocking as when Welch first discovered the centenarian orchid in the 19th century.

Whisper: the hundred-year-old orchid has only two hairs but not bald yet.

Reference:

Https://docs.qq.com/ doc / DU0FYYk9jUUZqeml5

This article comes from the official Wechat account: bring Science Home (ID:steamforkids), by Skin

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