Some plants die hard. At least that seems to be the lesson learned after moss retrieved from deep within the frozen ground of Antarctica was found to still have life left in it. Following in the footsteps of the discovery by a separate research team of moss revived after spending 4oo years beneath glacial ice, researchers from the British Antarctic Survey and the University of Reading set out to determine the viability of the innards of a moss bank encased in permafrost.
Mosses are ancient plants, predecessors to the more recently evolved (at least on a geological timescale) vascular plants. They produce no flowers or seeds and have no roots. Their leaves carry out photosynthesis – just like other plants – but they also absorb water and nutrients. There are about 12,000 species of mosses found in a wide range of habitats. Because they lack a vascular system, mosses require a damp environment (or at least one that is seasonally damp). While commonly seen growing in shady locations, there are some moss species that thrive in full sun, such as those growing on rocks in alpine environments. Mosses are the dominant vegetation in the polar regions where they can form thick moss banks in which an actively growing layer is underlain with moss that has slowly become incorporated into the permafrost.
The researchers in this study, which was published in the latest issue of Current Biology, took a core sample of a moss bank on Signy Island, Antarctica. The moss bank consisted of a single species – Chorisodontium aciphyllum. The sample core went 138 centimeters (4.5 feet) deep, and radio carbon dating of material taken from near the bottom of the core gave it an age of between 1533-1697 years old. The core was cut into several sections and then exposed to temperature and light conditions similar to the moss’s native environment. New growth occurred in many of the sections, but the most impressive finding was that after only 22 days, growth was noted in the 121-138 cm section, demonstrating that even after being frozen for more than 1500 years the moss was still alive. It was simply in a cryptobiotic state – a state in which all metabolic processes pause due to adverse environmental conditions.
Signy Research Station on Signy Island (photo credit: Wikimedia Commons)
Certain microbial life has been known to survive in a cryptobiotic state for tens of thousands of years, however this is the first time that a multicellular organism has been found to survive in such a state for longer than a few decades. So is their a moss species out there that has been surviving frozen conditions for even longer? It’s quite possible. And from an ecological standpoint, suspended animation is essential in order for polar mosses to survive periodic ice ages. Perhaps that’s why they have developed this remarkable trait.