Mushrooms helped plants to invade Earth Science | News | the sun

UThe team of international researchers, led by the Laboratory of Research Laboratory in Plant Sciences (LRSV) team in Toulouse III, found the missing link in a theory dating back to the 1980s. It assumes that the ancestor of all existing terrestrial plants, possibly freshwater algae that emerged from the water about 450 million years ago, lived in symbiosis with tiny fungi to thrive on Earth.

Today, about 80% of the earth’s plants use this symbiosis, in which the underground fungus is considered an “extension of the plant,” Pierre-Marc Delau told AFP. CNRS researcher at LRSV, who is the lead co-author of the study published in Science last week and signed by fellow and postdoctoral fellow Mélanie Rich. The fungus fungus, its vegetative apparatus, consists of an endless amount of tiny white filaments, which are intertwined in the ground. Its microscopic ends, closely related to the roots of the plant, provide it mainly with water, nitrogen and phosphate. In turn, the plant provides the fungi with fats, which are essential for their growth.

Sprawling hair

“If one of the partners stops feeding the other, the exchanges will stop in both directions,” and everyone suffers, explains Mr. Delaux: The fungus that depends “100% on the plant to grow,” as well as the plant, which can survive in a rich ecosystem but “will suffer much more.” In very poor soils. “

The consequences of stopping a symbiosis go further, as the fungi expand like sprawling hair. “Fungi are associated with hundreds, if not thousands, of plants at the same time,” says Delaux, who reported on “quite convincing work” about the role it could play in allocating resources in this ecosystem.

The researchers’ study showed that the same “symbiotic” gene, known to play a key role in transporting fats from plants to fungi, was operating in two main branches of terrestrial plants. So we can conclude that “their common ancestor who lived 450 million years ago also had these genes,” according to the researcher. The mechanism has already been well defined for vascular plants with stems and roots. Non-vascular plants, such as algae, are found called algae, “another large group of land plants”.

Moss is a mutant

Scientists have confirmed the role of the famous gene by depriving a “mutant” of foam. Marchantia Balicia. With the direct consequence of failure of coexistence, the stunted growth of fungi. To achieve its goals, the LRSV team worked with a group of European researchers, from the universities of Cologne, Zurich, Leiden and Cambridge, among others, and Japanese from the University of Sendai.

LRSV research is now heading towards a different kind of symbiosis, Mélanie Rich explains. What is being exerted among plants and “nitrogen fixing bacteria, which make it possible to recover nitrogen in the atmosphere and fertilize plants that coexist with it”.

This symbiosis is found in legumes such as lentils. The researchers hope to “recreate them with plants of agricultural importance such as wheat, corn and rice” and “contribute to the transfer of intensive agriculture that impoverishes the soil towards more sustainable agriculture,” the researcher adds. Because mastering this symbiosis would limit the extensive use of nitrogen fertilizers in rich countries, and offset their absence in poor countries, Africa and Southeast Asia.