According to new research, horizontal gene transfer from soil bacteria to algae has allowed early life to move to land.
"The movement of life from water to land – called continentalization – started with plants and was followed by animals," said University of Alberta professor Gane Ka-fu Wong.
"This study establishes how the first step happened."
Professor Wong and his colleagues made the discovery when they examined the DNA of two species of the algae family Zygnematophyceae: Spiroglobular muscle and Mesotaenium endlicherianum.
They have found genes that increase resistance to biotic and abiotic stresses in land plants (embryophytes) originate or expanded in the common ancestor of Zignamatophyte and land plants and have acquired horizontal gene transfer from soil bacteria.
"The movement of plants from water to soil was enabled when genes from the soil bacteria were transmitted to the algae through a process called horizontal gene transfer," they explain.
"Unlike vertical gene transfer, such as parent-to-child DNA transfer, a horizontal gene occurs between different species."
"For hundreds of millions of years, green algae lived in environments with freshwater environments that periodically fell dry, such as small puddles, river beds and rocky cliffs," said Professor Michael Melkonian, of the University of Duisburg-Essen.
"These algae blended in and got key soil bacteria bacteria that helped them and their offspring cope with the harsh land environment and eventually grow into the flora of the land plants we see today."
"The approach we have used, phylogeny, is a powerful method to point out the underlying molecular mechanism of evolutionary novelty," said Dr. Shifeng Sheng, of the Institute of Agricultural Genome, Chinese Academy of Agricultural Sciences.
The study was published in the journal Cell.
Shifeng Sheng et al. 2019 Cell 179 (5): 1057-1067; doi: 10.1016 / j.cell.2019.10.019