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Specimens of the narrow-leafed campion (Silene stenophylla) have been
regenerated from fruit tissue discovered in squirrel burrows buried under more
than 100 feet of Siberian permafrost, according to a recent paper from the Proceedings of the National Academy of
Sciences (PNAS).1 Radiocarbon dating has shown the fruit to be
approximately 32,000 years old, which makes the laboratory-grown plants the
oldest to have ever been cultivated from ancient tissue.
The plant material — discovered by researchers from the Geocryology Lab of the
Russian Academy of Sciences (RAS) — was found entombed in undisturbed
permafrost at below-freezing temperatures. Dating back to the late Pleistocene
period, the burrows contained upwards of 800,000 seeds of various species as
well as bones of mammoths, wooly rhinoceros, and bison. The authors of the PNAS
paper began by testing some of the plant material for signs of viability.
“Some of the species revealed the return of some physiological activity,” said
Svetlana Yashina, PhD, of the Institute of Cell Biophysics at RAS and a lead author of the journal article (e-mail, April 18,
2012). “Silene stenophylla turned out
most viable.”
Silene stenophylla continues to grow on the Arctic tundra, although its
documented uses are limited. “I can find no recorded uses for this species,”
said John Dickie, PhD, head of the Botanical Information Section of the
Millennium Seed Bank Partnership (MSBP) at the Royal Botanical Gardens, Kew, in
England. Its medicinal value is also undetermined, according to Dr. Yashina.
“However, many other members of the genus are used as ornamentals,” Dr. Dickie continued.
“While edible for humans, leaves of Silene
species are known to contain saponins, and they have been reported as being
used by tribal people for poisoning or stunning fish. [Also,] extracts from Silene multiflora are reported to have
anti-microbial activity.”
Before the publication of these findings, the record for the oldest seeds to
successfully germinate was 2,000 years. Scientists were able to grow a date
palm (Phoenix dactylifera) from seeds
that were collected 40 years earlier during excavations of the ancient fortress
city of Masada, Israel. The research team cited the area’s high summer
temperatures and low precipitation as possible reasons for the seeds’
longevity.2
The 30,000-year age difference between these 2 findings can be partially
explained by the methods used to cultivate the plants. “It is important to
remember that the regeneration achieved [by the Russian researchers] was not
from seed, but placental tissue,” said Dr. Dickie.
The physical location of the seeds was instrumental in their preservation as
well. In particular, Dr. Yashina mentioned the “location of the burrows against
the frozen … permafrost sediments and the fact that the burrows and their
content [had] never been defrosted since burial and simultaneous freezing.”
Additionally, the authors of the recent paper hypothesized that the S. stenophylla seeds remained viable
because they contained a high concentration of sucrose — which kept the
material from freezing — and phenolic compounds, which are known for their
protective qualities in response to stress.
The possibility of regenerating ancient, or even extinct, plant or animal
species often brings comparisons to the 1993 blockbuster film, Jurassic Park, where dinosaurs were
resurrected from 65 million-year-old DNA. “It’s scientifically exciting in all
kinds of ways, and it’s certainly the kind of thing that captures the general
public’s attention and imagination — the ‘Jurassic Park scenario,’” said Dr. Dickie.
However, there are more practical reasons for studying seed viability. “Being
able to resurrect ancient examples of present-day species potentially allows us
to explore a whole series of scientific questions around evolution,” he said.
“How well do plants derived from cells that have been in suspended animation
for thousands of years perform under today’s conditions in comparison with
their present-day descendants?”
These and similar research efforts could also lead to advances in seed
preservation, Dr. Dickie noted. “We are actively pursuing alternative methods
for long-term storage of plant germplasm in cases where seeds are not amenable
to ‘orthodox’ storage, including cryo-preservation of excised embryos and
tissues,” he added. “We await with interest the results of DNA analysis in
comparison with modern material, for additional, confirmatory reports of
similar spectacular survival from other permafrost sites.”
—Tyler Smith
References 1.
Yashina S, Gubin S, Maksimovich S, Yashina A,
Gakhova E, and Gilichinsky D. Regeneration of whole fertile plants from
30,000-y-old fruit tissue buried in Siberian permafrost. PNAS. 2012;109(10):4008-4013. Available at: www.pnas.org/content/early/2012/02/17/1118386109.
Accessed April 23, 2012.
2.
Sallon S, et al. Germination, genetics, and growth
of an ancient date seed. Science. 2008;320:1464.
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