'How plants evolved from water to land found'

Plants evolved from living in water to habiting land because of genes they took up from bacteria, according to a new study which establishes how the first step of large organisms colonising the land took place.

The researchers, including Gane Ka-Shu Wong, from the University of Alberta in Canada, said the habitation of plants from water to land was made possible when genes from soil bacteria were transferred to algae.

The study, published in the journal Cell, noted that plants obtained bacterial genes via a process called horizontal gene transfer, where DNA is transferred between species as opposed to vertical gene transfer where genes are transferred from a parent to a child.

"The movement of life from water to land -- called terrestrialisation -- began with plants and was followed by animals and then, of course, humans. This study establishes how that first step took place," Wong said.

The researchers said the study is part of an international project to sequence the genomes of more than 10,000 plant species.

"The approach that we used, phylogenomics, is a powerful method to pinpoint the underlying molecular mechanism of evolutionary novelty," said study first author Shifeng Cheng from the Chinese Academy of Agricultural Sciences.

The study noted that the discovery was made while sequencing the genomes of two particular algae -- one of them a new species called Spirogloea muscicola.

"For hundreds of millions of years, green algae lived in freshwater environments that periodically fell dry, such as small puddles, river beds, and trickling rocks," explained Michael Melkonian, study co-author from the University of Duisburg-Essen in Germany.

"These algae mingled with and received key genes from soil bacteria that helped them and their descendants to cope with the harsh terrestrial environment and eventually evolve into the land plant flora that we see today," Melkonian said.