Your latest work* plunges us into the heart of the “hyperconnected forest”. Could you explain to us what it is?
“Like a computer network, the constituent elements of a forest operate in interaction. From trees to mushrooms, including root and mycelial networks, without forgetting the invisible action of microbes. Forest organisms live in total interdependence. This is why a tree that dies is a whole world that disappears. »
You have made the study of symbiotic mechanisms between mushrooms and trees your specialty. Can a tree survive without fungus?
“Probably not.” Microorganisms are permanently present from the roots to the tops of trees. More than 90% of plant species live in perfect harmony with mycorrhizal fungi – fungi which have the particularity of entering into symbiosis with tree roots, thanks to their mycelium, these tiny filaments present in the soil. The fungus provides the plant with the water and nutrients necessary for its development. In return, the fungus is supplied with sugar from photosynthesis. It is therefore a symbiosis beneficial to both protagonists. It has existed for over 400 million years. »
Can some fungi harm plants and trees?
“Yes, they can also transmit diseases, such as chalarosis which affects ash trees. There are a good dozen of them. They are called pathogens. A third group of fungi (the first being the beneficial ones) is also well known to us. These are the decomposers. They reduce dead organisms (leaves, animals, branches, etc.) to powder, and produce humus, a substance greatly beneficial to the development of plants and good soil health. »
You have been studying the genetic and molecular mechanisms of mycorrhizal symbiosis for around forty years. Are there still things to discover?
” Of course. Especially since technologies, such as molecular biology tools, continue to advance. In terms of research, for example, we have recently demonstrated the existence of a dialogue between fungi and tree roots, with the fungi injecting small molecules preventing a plant rejection reaction. »
How many species of mushrooms do you estimate?
“Between two and five million. And we have only identified 150,000! This shows that there are still discoveries to be made.
*The hyperconnected forest (editions La Salamandre, 2022)
