Will genomics reveal the secrets of plant-plant interactions?

Transforming weeds into service plants, increasing yields by 50%, and reducing the amount of herbicides used in agriculture… What if genomics could fulfill our wildest dreams?

© Chitro Stock/Adobe Stock, DR

Within plant populations and communities, plants perceive the presence of other plants. At least, that’s what research from the Plant, Microbe, Environment Interactions Laboratory, led by Fabrice Roux, shows.

In this Inrae-CNRS laboratory located in Toulouse (France), a team of about fifteen people is studying, among other things, plant-plant interactions at the genomic level. To do this, they have developed a model based on the species Arabidopsis thaliana, commonly known as thale cress, a model species in laboratories and very common in rural areas.

Over 200 species

First, the scientists focused on describing the species in its natural environment, specifically in the former Midi-Pyrénées region. The data they acquired has notably helped characterize the plant communities associated with Arabidopsis, totaling more than 200 different plant species.

“We sequenced the genome of 168 natural populations of thale cress and identified genes that are markers of the diversity of plant communities,” explains the research director. “This discovery suggests that the diversity of communities seems to be inscribed in the genome of the plants that constitute them.”

Interactions still largely unknown

Fabrice Roux notes that, generally, thale cress interacts with an average of 12 plant species during its life cycle. “We call this the social network of plants. It can include up to 24 species in some cases. This figure applies to the majority of plant species,” he emphasizes.

What was the aim of the study? It was to identify the genetic mechanisms involved in plant-plant interactions. During their research, the scientists discovered that many genes present in these interactions are involved in the shade avoidance syndrome, typical of competition between species.

More surprisingly, the involvement of genes related to plant immunity has also been demonstrated: “We now believe that a plant’s response to the presence of another plant is not merely a mechanical and passive reaction. The immunity genes identified are well known for being linked to the perception of microbial signals. These responses would therefore be generated by active mechanisms,” explains Fabrice Roux with enthusiasm. In summary, a plant would perceive the presence of other plants rather than merely endure their presence.

A gene to facilitate coexistence

Following this discovery, the team confirmed the existence of a gene involved in the natural variation in response to competition. “This is a first,” explains Fabrice Roux. “It’s still quite astonishing to think that competition between plants is a predominant interaction within agricultural populations, yet this is the first time a gene involved in this competition response has been validated.”

The study of the mechanisms associated with this gene is just beginning. And although current research focuses on Arabidopsis thaliana, Fabrice Roux perfectly envisions finding similar genes in cultivated species, such as wheat or tomatoes.

“In the long term, we could find applications to facilitate the coexistence between cultivated species and weeds present in crops. It’s very promising, even though we don’t yet fully understand the mechanisms at work,” says the research director, who already imagines varietal improvements capable of reducing the amount of herbicides used in agriculture.

In addition to identifying these genes, the research team also observed yield increases of around 50% when certain Arabidopsis genotypes grow in the presence of another species: “Not only do these genotypes produce 50% more seeds, but at the end, the associated species disappears before Arabidopsis completes its cycle. It would be quite remarkable to reproduce this phenomenon in crops. Weeds would then become service plants, concludes Fabrice Roux.