Scientists at Oxford University have discovered the oldest known population of plant root stem cells in a 320-million-year-old fossil.
The cells, which gave rise to the roots of an ancient plant, were found in a fossilized root tip held in the Oxford University Herbaria.
As well as revealing the oldest plant root stem cells identified to date, the research also marks the first time an actively growing fossilised root has been discovered -- in effect, an ancient plant frozen in time.
The study is published in the journal Current Biology.
Oxford Plant Sciences PhD student Alexander (Sandy) Hetherington, who made the discovery during the course of his research, said: 'I was examining one of the fossilised soil slides held at the University Herbaria as part of my research into the rooting systems of ancient trees when I noticed a structure that looked like the living roots tips we see in plants today.
'I began to realise that I was looking at a population of 320 million-year-old plant stem cells preserved as they were growing -- and that it was the first time anything like this had ever been found.
'It gives us a unique window into how roots developed hundreds of millions of years ago.'
Stem cells -- self-renewing cells responsible for the formation of multicellular organisms -- are located in plants at the tips of shoots and roots in groups called meristems. The 320 million-year-old stem cells discovered in Oxford are different to all those living today, with a unique pattern of cell division that remained unknown until now. That tells us that some of the mechanisms controlling root formation in plants and trees have now become extinct and may have been more diverse than thought.