Insights into how plants moved to land 500 million years ago

A key factor which led plants to first emerge from water onto land 500 million years ago has been identified by new research led by evolutionary scientists from the University of Essex.

The study, published in the journal Current Biology, offers new insight into the evolution of plants and our understanding of the diversification of plant life on Earth – still one of the major challenges in evolutionary biology.

The evolution of plants on land has shaped our modern ecosystems and the diversification of the plant kingdom into more than 374,000 species we enjoy around the world today. Early land plants, for example, shaped the development of soils, rivers and our oxygen-rich atmosphere.

Researchers found the evolution of plants from water to land was boosted by two large bursts of new genes, one appearing just before and the other accompanying the establishment of plants on land 500 million years ago. This challenges the previous view of gradual changes at the genetic level during the emergence of land plants.

Led by Alex Bowles, from our School of Life Sciences, the study looked at 208 plant genomes ranging from wheat and soy to tomatoes and orchids. By comparing the complete gene sets of these living plant species, the research team were able to discover the genes which are shared between different plants and identify which genes enabled plants to move onto land.

“We have identified the most comprehensive list yet of genes that allowed plants to make the move from water to land. These genetic innovations were crucial to the evolution of all land plants that have shaped modern ecosystems,” explained Mr Bowles. “It is an exciting finding for our understanding of plant evolution.”

The study, which also involved scientists at the University of Bristol and the University of Oxford, identified 103 groups of genes which were fundamental to the origin of land plants. The number of new genes of land plants was far greater than any other major group of plants such as seed plants and flowering plants. Analysis of the function of these 103 genes revealed they were involved in land plant specific roles such as anchorage onto land and adaptation to stresses linked to a life outside water.

By comparing the genomes of living organisms, we have been able to understand how plants, alive half a billion years ago, made the transition onto land, dramatically altering the environments on Earth.

The next step in the research is to use similar techniques to answer more applied questions, such as identifying new drought-tolerant genes for crop plants.