Without plants on land, humans could not live on Earth. From mosses to ferns to grasses to trees, plants are our food, fodder and timber. All this diversity emerged from an algal ancestor that conquered land long ago.
The success of land plants is surprising because it is a challenging habitat. On land, rapid shifts in environmental conditions lead to stress, and plants have developed an elaborate molecular machinery for sensing and responding.
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Now, a research team led by the University of Göttingen has compared algae and plants that span 600 million years of independent evolution and pinpointed a shared stress response network using advanced bioinformatic methods. The results were published in Nature Communications.
Algal relatives
The closest algal relatives of land plants are the filamentous and unicellular conjugating algae, the zygnematophytes. This group of organisms has received major attention because when researchers compared data about land plants with data about these algae, they could trace back to the very first plants on land.
One of the big questions is how the earliest land plants overcame the terrestrial stressors. To find out, the team generated hundreds of samples from a moss model system and two zygnematophyte algae challenged by environmental stressors found on land.
Using high throughput sequencing of the active genes and profiling of the compounds produced by the moss and algae under stress, they obtained a comprehensive picture of how the organisms react to the challenges over a time-course of several hours. By combining evolutionary analysis with statistical modelling and machine learning methods, a shared network of gene regulation was predicted.
Highly connected genes
Professor Jan de Vries, Göttingen University, who led the research, explains: “One of the big surprises was that we found several highly connected genes – known as ‘hubs’ – in the network shared by these very different organisms that actually split from each other in evolutionary terms around 600 million years ago. These hubs appear to bundle information and shape the overall network response.”
“Now we have a comprehensive dataset of stress responses, combining genetic and biochemical information that can be further explored for its physiological impact across plant diversity,” adds Dr Tim Rieseberg, first author of the study and also at Göttingen University.
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