Small plants that reveal big secrets

Two studies recently published by a research team including Professor Juan Carlos Villarreal of Laval University demonstrate that modest, little-known plants can provide valuable fundamental knowledge about the evolution of life on Earth and inspire innovations that enable to increase agricultural production.

The plants in question are hornworts, a group related to the first plants that left the aquatic environment to settle on dry land 500 million years ago. “Even today, hornworts have characteristics that are present in algae, but which are not found in other land plants,” emphasizes Juan Carlos Villarreal, professor in the Department of Biology, member of the Institute of Biology integrative and systems and curator of the Louis-Marie Herbarium at Laval University.

So far, scientists have identified 223 species of hornworts around the world, but as they are little studied, this would be an underestimate, specifies the researcher. Quebec is home to 4 species of hornworts whose populations, concentrated in southern Quebec, are not very abundant.

With the team of Professor Fay-Wei Li, from Cornell University, Professor Villarreal studied the genomes of 10 species belonging to different families of hornworts to better understand how they had evolved from their common ancestor. These 10 species separated 300 million years ago, but, unlike several other groups of land plants, their chromosomes have remained surprisingly stable, this team reports in Nature Plants.

“On the other hand, they have developed accessory chromosomes, which are not essential for their survival, but which provide them with certain advantages. These accessory chromosomes evolve quickly and they are different between individuals, and even between different parts of the same plant,” underlines Professor Villarreal.

In another study published by Nature Plantsthe research team was interested in structures present only in algae and hornworts. Called pyrenoids, these structures contain enzymes that capture CO₂ and convert it into plant biomass during photosynthesis.

“Anthocerotes have a mechanism that allows them to concentrate CO₂ in their pyrenoids, which increases the efficiency of photosynthesis by 60% compared to that of other plants, underlines Juan Carlos Villarreal. Professor Li’s team is trying to integrate these pyrenoids into the genome of agricultural plants in order to increase their productivity. There should be significant progress in this area within five years.”

In plant research, there is a strong bias in favor of vascular plants, those which have roots and conductive vessels ensuring the circulation of sap, notes Professor Villarreal. “Scientists spend a lot of time and energy researching vascular plants. Conversely, modest and uncharismatic plants such as hornworts, mosses and liverworts are neglected, in particular because it is difficult to obtain funding to study them.

However, he argues, these plants manage to grow in the most inhospitable environments on the planet, they play key roles in the cycle of elements, particularly that of carbon, and they could help us better understand evolution. of life on Earth. Finally, their particularities could inspire us with unsuspected applications. “It’s time to end chauvinism in plant research. “By broadening our horizons to include hornworts, mosses and liverworts, we are embarking on a path that will lead us to a more comprehensive understanding of the plant kingdom.”