According to a CNRS communication dated October 16, 2025. Based on a scientific publication in Current Biology to which the RDP laboratory at ENS de Lyon contributed: "Robust branch patterning in moss shoots via symplasmic auxin diffusion." Image © Des Callaghan
In an article published in Current Biology , scientists explore how auxin, a plant hormone, travels through the stem of moss to shape its architecture. For several decades, auxin has been known to be actively transported between cells in vascular plants, such as most grasses and trees, using specialized molecular pumps. The study reveals that, in the moss Physcomitrium patens, a much simpler auxin diffusion mechanism is sufficient to explain how the structure is formed, highlighting the evolutionary originality of this branch of life.
Auxin, molecular architect of plant shape
Plants come in an incredible variety of shapes. Some are tall and slender, others short and highly branched. One reason for this difference lies in the way they organize the growth of their branches. This process is controlled by a hormone called auxin.
Auxin acts a bit like a position marker: it is produced in different parts of the plant-at the top and base of the stems and in the branches-and creates zones of inhibition along the stem, i.e. places where the formation of new branches is blocked. The spacing between these zones largely determines the overall shape of the plant.
In vascular plants, auxin circulates actively thanks to small molecular pumps that direct its transport in a single direction. But in mosses such as Physcomitrium patens, this system seems to be much less important. Genetic studies had already shown that auxin transport by these pumps plays a limited role in how these plants branch out. This raised the question: how do mosses manage to organize their branches with such precision despite this?
Read more on the CNRS website
Reference
Abitbol-Spangaro J, Cloarec G, Muller A, Hallet S, Boulogne C, Gillet C, Schmidt V, Dobrev PI, Skokan R, Couvreur V, de Keijzer J, Godin C, Coudert Y. Robust branch patterning in moss shoots via symplasmic auxin diffusion. Curr Biol. 2025 Oct 7:S0960-9822(25)01201-1. DOI: 10.1016/j.cub.2025.09.031
