400 year-old frozen plants resuscitated
Plants entombed in glacial ice for more than 400 years have been successfully resuscitated by scientists in Canada.
The bryophytes, forms of moss including liverworts, have been revealed in the Canadian Arctic by the melting of the Ellesmere Island "Teardrop Glacier," which is retreating at between 3 and 4 metres per year.
Catherine La Farge, a researcher at the University of Alberta, noticed on a visit to the area that, as the ice receded, a matt of dark plant material was being revealed, some of which appeared, a short while later, to be green and showing signs of regrowth. She and her colleagues collected samples of the plants and placed them in culture media in the laboratory.
Other samples were used for carbon dating, which confirmed that the material was 400 and 600 years old and was probably buried in ice during the Little Ice Age in medieval times. Of 24 specimens put up for culture, 7 grew, regenerating viable plants.
That these plants can remain viable for so long under freezing conditions reflects their ancient origins, over 470 million years ago. They are very simple organisms which, unlike their more recently evolved counterparts, lack a vessel system for transporting water in the plant.
As such, they have little control over water movement through and to their tissues, so they have evolved to be highly tolerant of dessication, shutting down the activity of their cells when water is scarce. At the same time, all of their cells are capable of regenerating a new plant, behaving like a totipotent stem cell seen in animals.
Together, these traits make bryophytes highly successful pioneer species that can colonise harsh terrain. And now we also know, thanks to this work published this week in PNAS, that they probably also make a hitherto unrecognised contribution to the re-establishment of plant ecosystems in polar regions as glaciers retreat...