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article imageScientists bring plant 30,000 yrs in Siberian permafrost to life

By JohnThomas Didymus     Feb 21, 2012 in Science
Fruit placental tissue of the herbaceous Silene stenophylla found in Siberian permafrost, and believed to have been stored by squirrels more than 30,000 years ago have been regenerated into full flowering plants by Russian scientists.
AFP reports that in a lab near Moscow, scientists had first tried to regenerate the plant from the seeds, but when they failed, they used the plant's placental tissue, the fruit structure to which seeds attach, and successfully regenerated the whole plant in pots under controlled light and temperature.
According to AP, the study is a pioneering experiment that paves way for revival of long extinct species. The study says: “We consider it essential to continue permafrost studies in search of an ancient genetic pool, that of pre-existing life, which hypothetically has long since vanished from the earth’s surface."
According to lead researchers Svetlana Yashina and David Gilichinksy of the Russian Academy of Sciences, the tissues are the oldest plant tissues brought back to life.
AFP describes the achievement as a landmark in the ongoing research on ancient biological material and efforts to revive prehistoric species some of which have gone extinct. The researchers said that their study highlights the importance of permafrost in the "search of an ancient genetic pool, that of preexisting life, which hypothetically has long since vanished from the earth's surface."
The previous record for regeneration of ancient biological material was held by 2,000-year-old date palm seeds at the Masada fortress near the Dead Sea in Israel.
The tissues of the Silene stenophylla plant have been estimated by radiocarbon dating at about 31,800 years old. Svetlana Yashina of the Institute of Cell Biophysics of the Russian Academy of Sciences said the plant looked very similar to the modern version, though there were subtle differences. She said: “It’s a very viable plant, and it adapts really well."
The plant materials were found in 70 squirrel hibernation burrows along the bank of the lower kolyma river in Russia's northeast Siberia. The burrows bore hundreds of thousands of seed samples from various other plants. According to the study; "All burrows were found at depths of 20-40 meters (65 to 130 feet) from the present day surface and located in layers containing bones of large mammals such as mammoth, woolly rhinoceros, bison, horse, deer, and other representatives of fauna," all dating to the late Pleistocene.
The permafrost helped to preserve the tissues by freezing them up. They were preserved for so long because burrows were very quickly covered in ice and remained "continuously frozen and never thawed" for 30,000 years. They remained at an average temperature of -7 degrees Celsius (19 Fahrenheit) for tens of thousands of years, AP reports. This prevented degradation, allowing scientists to regenerate them into flowering plants again. According to Stanislav Gubin, one of the authors of the study, “The squirrels dug the frozen ground to build their burrows, which are about the size of a soccer ball, putting in hay first and then animal fur for a perfect storage chamber. It’s a natural cryobank.”
BBC reports that Robin Probert, head of conservation and technology at the UK's Millennium Seed Bank, said, "This is by far the most extraordinary example of extreme longevity for material from higher plants. I'm not surprised that it's been possible to find living material as old as this, and this is exactly where we would go looking, in permafrost and these fossilised rodent burrows with their caches of seeds.But it is a surprise to me that they're finding viable material from this placental tissue rather than mature seeds."
The Russian scientists believe, however, that it was possible to regenerate the plant from placental tissue because it is full of sucrose that provides nourishment for the growing plant. Sugars are also used as preservatives and the sugar-rich placental cells might have helped to keep the tissue viable for so long.
Grant Zazula of the Yukon Paleontology Program at Whitehorse in Yuon Territory Canada, said: "This is an amazing breakthrough. I have no doubt in my mind that this is a legitimate claim."
Earlier claims of regeneration from ancient plant tissues have been disputed by Zazula. North American Arctic plants grown from seeds claimed to be 10,000 years old in the mid-20th century have been shown to contain contaminants from modern plants. But care was taken in the present study to confirm that the ancient materials used were not contaminated by material from modern S. stenophylla which still grows in the Siberian tundra.
BBC reports that scientists are also looking for preserved Mammoth remains in the banks of the lower Kolyma river in Russia's northeast Siberia. According to AP, Japanese scientists have been searching the area for mammoth remains but Gubin hopes that Russians will find them first. He said: “If we are lucky, we can find some frozen squirrel tissue. And this path could lead us all the way to mammoth. It’s our land, we will try to get them [before the Japanese]."
BBC reports that the lead researcher Professor David Gilichinsky, died before the paper was published in the Proceedings of the National Academy of Sciences.
More about Permafrost, siberian permafrost, Seeds, 30000 yrs
 
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