"A mycorrhiza, from the Greek myco-, 'fungus,' and rhiza, 'root,' is a type of symbiotic relationship between a plant and a fungus that has existed since the colonization of land by plants, several million years ago," explained Alexis Carteron, lead author of the study.

"This positive association for both partners is unquestionably the most widespread and important form of 'mutualistic symbiosis' in terrestrial ecosystems."

Carteron has a Ph.D. in biology from Université de Montréal and is currently working as a post-doctoral researcher in the Department of Environmental Science and Policy at the University of Milan, Italy.

In botany, mycorrhizal fungi have long been known to provide plants with significant nutritional benefits by extending their root systems up to 10 times the initial root surface and enabling them to better absorb water and minerals from the soil. For instance, mycorrhizal fungi are able to dissolve phosphorus in the soil, making it available to plants. In return, the plant provides the fungi with sugar produced through photosynthesis.

"For some time now, there has been growing interest in the important role of mycorrhizal fungi in plant biodiversity," said the supervisor of the study, Etienne Laliberté, Canada Research Chair in Plant Functional Biodiversity at Université de Montréal.

Two strategies for fungi

The two main types of mycorrhizas, ectomycorrhizas and arbuscular mycorrhizas, seem to influence the diversity of tree species in forests in different ways.

Ectomycorrhiza affects about 2 percent of plant species, mostly conifers in Northern Hemisphere forests. Arbuscular mycorrhiza, the oldest and most widespread form of symbiotic association between fungi and plants, affects 80 percent of terrestrial plants. The two differ in the way the fungus attaches to the plant's roots.

Scientists have observed that forests with soils colonized by arbuscular mycorrhiza are more diverse. Species-rich tropical rainforests, for instance, are composed mainly of arbuscular mycorrhizal trees, while species-poor boreal forests are dominated by ectomycorrhizal trees.

https://phys.org/news/2022-02-secret-mycorrhizal-fungi.html