Scientists think it’s possible that two genes, PEN1 and SYP122, paved the way for all kinds of land plant life.
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Researchers have explained how plant life originated on Earth
researcher from University of Copenhagen This has explained how plant life originated on the surface of our planet. Specifically, they showed that two genes are required for terrestrial plants to protect themselves from fungal attack – a defense mechanism that dates back 470 million years. Most likely this defense paved the way for all land plant life.
Mads Egggert Nielsen, a biologist at the University of Copenhagen.
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Plants evolved from aquatic algae to the ability to survive on Earth nearly half a billion years ago, laying the foundation for life on Earth. One of the obstacles that made this dramatic transformation so difficult was the fungus:
It is estimated that 100 million years ago, fungi slithered across the Earth’s surface in search of food, most likely found in dead algae that washed up from the ocean. So if you, as a new plant, are going to establish yourself on Earth, and the first thing you encounter is a fungus that eats you, you need some sort of defense mechanism,” said Mads Egggert Nielsen, a biologist with the Department. Plant and Environmental Sciences at the University of Copenhagen.
According to Mads Egggert Nielsen and research associates from the Department of Plant and Environmental Sciences and the University of Paris-Sclay, the core of this defense mechanism can be narrowed down 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 Arabidopsis model, we open the door for pathogenic fungi to penetrate. We found that they are important for the formation of plugs such as cell walls that protect against fungi. Interestingly, it appears to be a universality defense mechanism found in all terrestrial plants,” said Mads Egggert 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 liverworts, a direct descendant of one of the first land plants on Earth. By taking two matching genes in liverworts and inserting them into lettuce, the researchers examined whether they could determine the same effect. The answer is yes.
Experiment with Arabidopsis Model Credits: Mads Egggert Nielsen
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“Although the two plant families in which Arabidopsis and liverworts evolved in different directions 450 million years ago, they continue to share genetic functions. We believe that this gene family emerged with the unique purpose of managing this defense mechanism, and therefore constitutes a single entity. Who set up factories to build themselves on the ground,” said Mads Egggert Nielsen.
The coexistence of plants and fungi
While fungi are a barrier to plants in their transition from marine algae to land plants – they are also a prerequisite. Mads Egggert Nielsen explains that once plants are able to survive the onslaught of fungi that want to eat them on Earth, the next problem they face is finding nutrients:
Plants in aquatic environments have easy access to dissolved nutrients such as phosphorus and nitrogen. But 500 million years ago, land as we know it today didn’t exist – only rock. Nutrients bound to rock are very difficult for plants to obtain. But not for mushrooms. On the other hand, fungi cannot produce carbohydrates – which is why they consume plants. It is here that the symbiotic relationship between plants and fungi is believed to have emerged, which later became the basis for the explosion of land plant life during this period.”
The defensive structures that form in plants do not kill the plant or the fungus, they only prevent the fungus from attacking.
“Because the fungus can only partially enter the plant, we believe a tipping point arises where the plant and the fungus have something to gain from. Hence, it is helpful to keep the relationship as it is. The theory that plants tame fungi to colonize their soil is not ours, but we provide animal feed that supports this idea,” says Mads Egggert Nielsen.
Can be applied in agriculture
The new findings add an important piece to the puzzle of the evolutionary history of plants. More importantly, they can be used to make crops more resistant to fungal attack, which is a big problem for farmers.
“If all plants defend themselves in the same way, this means that microorganisms that can cause disease – such as powdery mildew, yellow rust and potato rot – have found a way to infiltrate, stop or evade their respective host plant defenses. We want to know. How do they do it. We will then try to transfer the defense components from the resistant plants to the diseased plants, and thus achieve resistance,” said Mads Egggert Nielsen.
Mads Egggert Nielsen is participating in a research project in the Department of Botanical and Environmental Sciences led by Hans Thordal-Christensen and supported by the Novo Nordisk Foundation that focuses on making plants more resistant by identifying defense mechanisms in plants that disease-causing microorganisms try to overcome. close.
Additional facts
Researchers have long assumed that the PEN1 and SYP122 genes perform specific functions regarding the transition of plants from their aquatic phase as algae to land plants, but there has been no concrete evidence whether they are indeed prerequisites for plants. defensive ability.
Previous studies have shown that by destroying the PEN1 gene, plants lose their ability to defend themselves against powdery mildew. However, when the closely related gene, SYP122, was destroyed, nothing happened. The results of the new study show that the two genes together are an important key in plant defense mechanisms.
Reference: “Plant SYP12 structures mediate evolutionarily conserved general immunity against nematode pathogens” By Hector M Rubiato, Mingqi Liu, Richard J O’Connell and Mads E. Nielsen, 4 Feb 2022, Available here. eLife.
DOI: 10.7554 / eLife.73487
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