Know more

For billions of years, life has been confined to water, oceans, seas and lakes. Four hundred and fifty million years ago, plants colonized land, leading to massive changes of our planet and the evolution of ecosystems containing a unique animal, microbial and plant biodiversity. It is well recognized that this colonization event was possible, among other things, thanks to the mutual beneficial interactions of these first plants with certain fungi that help to supply nutrients and water to the plants. If this type of symbiosis is now present in 80% of the plants, it is no longer the only one. Indeed, many symbiotic associations have evolved in a large range of plants such as soybean and vanilla.

Plant-microbe symbiosis, a long-term co-evolution

Many researchers from around the world try to understand how these symbioses work and how they may have evolved. These questions are fascinating in two aspects. First, these symbioses correspond to a high-interaction intimacy between living organisms: the microbial symbiont is hosted inside the plant cells. On the other hand, these symbioses have essential ecological functions and are present in almost all existing ecosystems. Understanding these symbiosis and the underlying mechanisms offers the possibility of better exploiting them in agronomy, which would in turn facilitate the transition to more eco-friendly  farming practices.

For several decades, the research mainly conducted on two plant symbioses has led to the identification of many plant genes involved in the recognition of symbionts and their hosting inside the plant cell. Up to date, the other intracellular symbioses have been little studied.

A handful of genes common to all plant symbioses

In order to go deeper in understanding plant symbiosis, researchers at the LRSV compared the genomes of more than 400 plant species that are able of forming one or more of these "intracellular" symbiosis. In this set of plants, researchers also selected species that have lost the ability to associate with these symbionts. Remarkably, whatever the type of symbiosis, all plant species presenting symbiotic relationships share three genes that have been systematically lost in "non-symbiotic" species. This observation clearly indicates that the great diversity of symbiosis observed in plants is built on a common molecular core set!

Towards new symbioses in agriculture

This work was performed in the context of the ENSA project (Engineering Nitrogen Symbioses for Africa, https://www.ensa.ac.uk/), an initiative aiming at introducing new symbiosis in major crops such as corn, wheat or cassava. Such symbiosis would largely reduce chemical inputs in crop fields, while increasing crop yield in regions of the world where costly fertilization is not an option. By demonstrating that symbioses share the same genetic basis, this work reinforces the credibility of this ambitious objective.