Fruits in my fruit bowl tend to rot into a mulchy mess after a couple of weeks. Fruits that are chilled in permanent Siberian ice fare rather better. After more than 30,000 years, and some care from Russian scientists, some ancient fruits have produced this delicate white flower.
These regenerated plants, rising like wintry Phoenixes from the Russian ice, are still viable. They produce their own seeds and, after a 30,000-year hiatus, can continue their family line.
The plant owes its miraculous resurrection to a team of scientists led by David Gilichinsky, and an enterprising ground squirrel. Back in the Upper Pleistocene, the squirrel buried the plant’s fruit in the banks of the Kolyma River. They froze.
The 30,000 year-old Silene stenophylla seeds that were regenerated into plants by Russian scientists were discovered in a fossilized squirrel burrow in permafrost along the banks of the Kolmya River in Russian Siberia
Over millennia, the squirrel’s burrow fossilised and was buried under increasing layers of ice. The plants within were kept at a nippy -7 degrees Celsius, surrounded by permanently frozen soil and the petrifying bones of mammoths and woolly rhinos. They never thawed. They weren’t disturbed. By the time they were found and defrosted by scientists, they had been buried to a depth of 38 metres, and frozen for around 31,800 years.
People have grown plants from ancient seeds before. In 2008, Israeli scientists resurrected an aptly named Phoenix palm from seeds that had been buried in the 1st century. But those seeds were a mere 2,000 years old. Those of the new Russian flower – Silene stenophylla – are older by an order of magnitude. They trump all past record-holders.
Svetlana Yashina from the Russian Academy of Sciences grew the plants from immature fruits recovered from the burrow. She extracted their placentas – the structure that the seeds attach to – and bathed them in a brew of sugars, vitamins and growth factors. From these tissues, roots and shoots emerged.
Yashina potted the plants and two years later, they developed flowers. She fertilised the ancient flowers with each other’s pollen, and in a few months, they had produced their own seeds and fruits, all viable. The frozen plants, blooming again after millennia in the freezer, seeded a new generation.
S.stenophylla is still around, but Yashina found that the ancient plants are subtly different to their modern counterparts, even those taken from the same region. They’re slower to grow roots, they produce more buds, and their flower petals were wider.
This is the first time that anyone has grown plants form seeds deeply buried within permanently frozen burrows. But it’s not the first time that someone has tried. In 1967, Canadian scientists claimed that they had regenerated Arctic lupin from 10,000 year old seeds that had been buried by lemmings. But in 2009, another team dated those same seeds and found that they were actually modern ones, which had contaminated the ancient sample.
Mindful of this mistake, Yashina carefully checked that her plants were indeed ancient ones. She dated the seeds directly, and her results matched age estimates from other samples from the same burrow. The burrows have been buried well below the level that animals dig into, and the structure of the surrounding ice suggests that they have never thawed. Their sediments are firmly compacted and totally filled with ice. No water infiltrates these chambers, much less plant roots or modern rodents. There are a few pores, but they are many times narrower than the width of any of Yashina’s seeds.
This closed world provided shelter, a continuous chill, and an effectively dry environment, that allowed the fruits to persist. At subzero temperatures, their chemical reactions slowed to a crawl. Extreme age was no longer a problem. A fruit’s placenta is also chemically active, and is loaded with several chemicals that might have protected these specific tissues against the cold.
But the burrows weren’t completely benign environments. The underground rocks contain naturally radioactive elements, which would have bombarded the seeds with low but accumulating doses of radiation. The ones that Yashina regenerated would have amassed 70 Grays of radiation – that’s more than any other plant has absorbed while still producing viable seeds.
S.stenophylla’s resurrection shows how many treasures lie buried within the world’s permafrost. This soil, defined as that which stays below freezing for two years or more, covers a fifth of the planet’s land. It is home to bacteria, algae, fungi, plants and more. In the fossil burrows that Yashina has studied, scientists have found up to 600,000 to 800,000 seeds in individual chambers.
In Norway’s Svalbard Global Seed Vault, scientists have frozen thousands of seeds in an underground cavern, as a back-up in case of agricultural crises. But nature has already produced similar frozen seed banks. Siberia, Alaska and the Yukon could act as one massive freezer, where ancient life has been stored, waiting to greet the world again.
COMMENTARY: This is an amazing scientific breakthrough if the regeneration of the 32,000 year-old seeds can be confirmed by other scientists.
UPDATE: Tragedy has now struck the Russian team that was involved in the discovery of the 32,000 year-old seeds and the successful regeneration of a living plant from those seeds. Dr. David Gilichinksy, its leader, was hospitalized with an asthma attack and unable to respond to questions, his daughter Yana said on Friday. On Saturday, Dr. Price reported that Dr. Gilichinsky had died of a heart attack.
According to The New York Times, this incredible scientific breakthrough in plant regeneration from seeds that were carbon dated to be 32,000 years-old, is by a team led by Svetlana Yashina and David Gilichinsky of the Russian Academy of Sciences research center at Pushchino, near Moscow, and appears in Tuesday’s issue of The Proceedings of the National Academy of Sciences of the United States of America.
Grant Zazula of the Yukon Paleontology Program at Whitehorse in Yukon Territory, Canada said.
“This is an amazing breakthrough. I have no doubt in my mind that this is a legitimate claim.”
It was Dr. Zazula who showed that the apparently ancient lupine seeds found by the Yukon gold miner were in fact modern.
But the Russians’ extraordinary report is likely to provoke calls for more proof. Alastair Murdoch, an expert on seed viability at the University of Reading in England said.
“It’s beyond the bounds of what we’d expect.”
When poppy seeds are kept at minus 7 degrees Celsius, the temperature the Russians reported for the campions, after only 160 years just 2 percent of the seeds will be able to germinate, Dr. Murdoch noted.
Some of the storage chambers in the squirrel burrows contain more than 600,000 seeds and fruits. Many are from a species that most closely resembles a plant found today, the narrow-leafed campion (Silene stenophylla).
Working with a burrow from the site called Duvanny Yar, the Russian researchers tried to germinate the campion seeds, but failed. They then took cells from the placenta, the organ in the fruit that produces the seeds. They thawed out the cells and grew them in culture dishes into whole plants.
Many plants can be propagated from a single adult cell, and this cloning procedure worked with three of the placentas, the Russian researchers report. They grew 36 ancient plants, which appeared identical to the present day narrow-leafed campion until they flowered, when they produced narrower and more splayed-out petals. Seeds from the ancient plants germinated with 100 percent success, compared with 90 percent for seeds from living campions.
The researchers suggest that special circumstances may have contributed to the remarkable longevity of the campion plant cells. Squirrels construct their larders next to permafrost to keep seeds cool during the arctic summers, so the fruits would have been chilled from the start. The fruit’s placenta contains high levels of sucrose and phenols, which are good antifreeze agents.
The Russians measured the ground radioactivity at the site, which can damage DNA, and say the amount of gamma radiation the campion fruit accumulated over 30,000 years is not much higher than that reported for a 1,300-year-old sacred lotus seed, from which a plant was successfully germinated.
The Russian article was edited by Buford Price of the University of California, Berkeley. Dr. Price, a physicist, chose two reviewers to help him. But neither he nor they are plant biologists. He said.
“I know nothing about plants.”
Ann Griswold, a spokeswoman for PNAS, as the journal is known, said the paper had been seen by an editorial board member who is a plant biologist.
Eske Willerslev, an expert on ancient DNA at the University of Copenhagen, said the finding was “plausible in principle,” given the conditions in permafrost. But the claim depends on the radiocarbon date being correct:
“It’s all resting on that — if there’s something wrong there it can all fall part.”
If the ancient campions are the ancestors of the living plants, this family relationship should be evident in their DNA. Dr. Willerslev said that the Russian researchers should analyze the DNA of their specimens and prove that this is the case. However, this is not easy to do with plants whose genetics are not well studied, Dr. Willerslev said.
If the claim is true, then scientists should be able to study evolution in real time by comparing the ancient and living campions. Possibly other ancient species can be resurrected from the permafrost, including plants that have long been extinct.
Courtesy of an article dated February 20, 2012 appearing in Discover Magazine blog, an article dated February 21, 2012 appearing in The New York Times, an article dated February 21, 2012 appearing in The Guardian and an article dated February 21, 2012 appearing in io9.com