Mads Eggert Nielsen

Two crucial genes have been identified for plants that colonized the Earth 470 million years ago

Scientists think it’s possible the two genes, PEN1 and SYP122, paved the way for all kinds of terrestrial plants.

Researchers have shed new light on how plant life originated on Earth

researchers of University of Copenhagen It has shed new light on how plant life originated on the surface of our planet. They specifically showed that two genes are necessary for terrestrial plants to protect themselves from attack by fungi — a defense mechanism that dates back 470 million years. It is likely that these defenses paved the way for all the plants on the land.

Mads Eggert Nielsen, a biologist at the University of Copenhagen.

Plants evolved from aquatic algae to the ability to survive on Earth nearly half a billion years ago and laid the foundation for life on Earth. One of the obstacles that made this dramatic transformation so difficult was the fungi:

An estimated 100 million years ago, fungi crawled across the Earth’s surface in search of food, most likely found in dead algae washed up from the sea. So if you’re going to establish yourself as a new plant on the ground and the first thing you encounter is a fungus that eats you, you need some kind of defense mechanism,” says Mads Eggert Nielsen, biologist in the Department of Plant and Environmental Sciences at the University. from Copenhagen.

According to Mads Eggert Nielsen and research colleagues from the Department of Plant and Environmental Sciences and the University of Paris-Sclay, the core of this defense mechanism can be reduced to two genes, PEN1 and SYP122. Together, they help form a type of component in plants that prevents the invasion of fungi and fungus-like organisms.

“We found that if we destroy these two genes in our model of Arabidopsis, we open the door for pathogenic fungi to enter. We found that they are essential for the formation of this cell wall-like plug that protects against the fungi. Interestingly, it appears to be a universal defense mechanism found in all terrestrial plants,” said Mads Eggert Nielsen, senior author of the study, which was published in the journal Science. eLife

I grew up in a 470 million year old factory

The research team tested the same function in the liverwort, a direct descendant of one of the first land plants on Earth. By taking the two matching genes in the liverwort and inserting them into cress, the researchers examined whether they could identify the same effect. The answer was yes.

Plant model Thale Cress

Experiments with Arabidopsis Model Credit: Mads Eggert Nielsen

“Although the two plant families to which Arabidopsis and liverwort evolved in different directions 450 million years ago, they continued to share genetic functions. We believe this family of genes came into existence for the unique purpose of managing this defense mechanism, and so it was someone who founded plants to establish themselves on the ground,” says Mads Eggert Nielsen.

The coexistence of plants and fungi

While fungi were an obstacle for plants in their transition from marine algae to land plants, they were also a requirement. Mads Eggert Nielsen explains that once plants could survive the onslaught of the fungi they wanted to eat on Earth, the next problem they faced was finding nutrients:

Plants in aquatic environments have easy access to dissolved nutrients such as phosphorus and nitrogen. But 500 million years ago, the soil as we know it today didn’t exist — just rocks. Nutrients bound to the rocks are extremely difficult for plants to obtain. But not for fungi. On the other hand, fungi cannot produce carbohydrates – that is why they consume plants. This is said to have created the symbiotic relationship between plants and fungi, which later became the basis for the explosion of terrestrial plant life during this period.”

The defense structures that form inside the plant do not kill the plant or the fungus, they simply prevent the fungus from entering.

“Because mushrooms can only partially enter the plant, we think there is a tipping point where both the plant and the fungus have something to gain. That’s why it was helpful to keep the relationship as it is. The theory that plants tame fungi to colonize the land Not ours, but we provide feed that supports this idea,” says Mads Eggert Nielsen.

Can be applied in agriculture

The new findings add an important piece to the puzzle of plant evolutionary history. More importantly, they can be used to make crops more resistant to fungal attack, which is a major problem for farmers.

“If all plants defend themselves in the same way, it should mean that microorganisms that can cause disease – such as powdery mildew, yellow rust and potato rot – have found a way to infiltrate, stop or suppress the defenses of their respective host plants. dodge. We want to know. How do they do that. We will then try to transfer the defense components from the resistant plants to those that get disease, and thus achieve resistance,” says Mads Eggert Nielsen.

Mads Eggert Nielsen participates in a research project at the Department of Botanical and Environmental Sciences led by Hans Thordal-Christensen and supported by the Novo Nordisk Foundation, which focuses on making crops more resistant by identifying defense mechanisms in plants that harbor disease-causing microorganisms. try to tackle. close to.

Additional facts

Researchers have long believed that the genes PEN1 and SYP122 served a special function in the transition of plants from their aquatic phase as algae to terrestrial plants, but there is no concrete evidence that they are indeed a requirement for plants. defensive capabilities.

Previous studies have shown that by destroying the PEN1 gene, plants lose their ability to defend against powdery mildew. However, when the closely related gene, SYP122, is destroyed, nothing happens. The new research results show that the two genes together form an important key in the plant’s defense mechanism.

Reference: “Plant SYP12 Structures Mediate an Evolutionarily Conserved General Immunity to Nematode Pathogens” by Hector M Rubiato, Mingqi Liu, Richard J O’Connell, and Mads E. Nielsen, Available Feb. 4, 2022. eLife.
DOI: 10.7554 / eLife.73487

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