The idea of starting ancient life from ancient seeds has not always been the stuff of science fiction. Scientists have induced ancients seeds to grow and produce flowers and fruit before, but a recent experiment has broken all records. The process is called viable regeneration of ancient flora, and the previous age record was achieved with some 2000 year old date palm seeds from the the Masada fortress near the Dead Sea in Israel. That record was recently beaten by 28,000 years when Russian scientists grew plants from 30,000-year-old fruit.
The scientists managed to resurrect a old flower from seeds that date back to the Pleistocene era. The seeds are believed to have been saved when squirrels stored them away over 30,000 years ago and the Siberian permafrost acted like a permanent freezer.
The plant, a herbaceous Silene stenophylla came from a variety of seed samples that were recovered when 70 squirrel hibernation burrows were discovered along the bank of the lower Kolyma river in northeast Siberia. The depth was between 20 to 40 meters (65 to 131 feet) and the enormous cache yielded up hundreds of thousands of various seeds.
ABC Science reports that a very important part of the process was to conduct radiocarbon tests. The tests confirmed that the stash had not been contaminated with modern versions of Silene Stenophylla, which still grows in Siberia. In one case, a Yukon gold miner found Arctic Lupine seeds that were claimed to be 10,000 years old, but were actually modern versions. Thus, the radiocarbon dating adds to the legitimacy of the Russian discovery.
The regenerated S. stenoplylla is slightly different from the modern version of the plant, with subtle differences in petal shape and the sex of the flowers. This observation adds to the legitimacy of the claim.
The freezing process and the way in which the material remained frozen allowed the scientists to regenerate the seeds. It is believed that the material was frozen rather quickly, then remained frozen as the permafrost acted like a "giant freezer". The process kept the material undisturbed and frozen solid at -7 degrees Celsius (19 degrees Fahrenheit), and created a perfect 30,000 year dormancy.
The mature seeds of the S. stenophylla did not germinate and grow, so the scientists went for parts of the the placental tissue, or flesh, of three fruits that had not germinated. A plant's placental tissue contains sucrose that feeds the seeds and is where the seeds attach. Sucrose is also believed to act as a preservative.
That sugar can act as a preservative has been known for a while, and sucrose is being investigated as a way to keep vaccines fresh. In the ancient plants, the pre germination state made the placental tissue viable for growing in pots of soil that were kept under controlled conditions of light and temperature.
According to BBC News, the lower Kolyma river is popular with researchers who search for mammoth bones. Botanists were also interested in the area because they knew that the frozen conditions and the presence of rodent burrows could lead to well preserved seed caches. This increased the likelihood that the burrows would be found in such a massive and rugged area.
The presence of vertical ice wedges indicate that the permafrost was permanently frozen and never thawed. Other indications were that the squirrels stored the seeds in what were the coldest parts of their burrows at the time. Rapidly changing local weather conditions are estimated to have caused the quick and permanent freeze.
The research team was led by Professor David Gilichinsky, who died on February 18th, a few days before his project's paper was published. Dr Gilichinsky was remembered by Association of Polar Early Career Scientists,
"It is with sad hearts that we announce that Dr. David Gilichinsky, longtime Head of Geocryology Lab, Institute for Physicochemical and Biological Problems in Soil Science at the Russian Academy of Sciences, passed away Saturday, 18 February 2012. Dr. Gilichinsky was an internationally respected scientist, beloved friend and colleague, and supportive mentor for his students and APECS' efforts."