What if leaves of different evolutionary origins relied on the same developmental rules?
A study published in Science Advances shows that, in moss and the model plant Arabidopsis thaliana, commonly known as thale cress, leaf formation relies on very similar cellular dynamics, with growth concentrated at their base.
Led by scientists at Université de Montréal, the study also reveals that auxin, a key hormone in plant development, controls cell division and elongation in both cases, but through distinct transport mechanisms.
By highlighting both convergences and divergences, the research sheds light on how evolution reuses common principles while adapting them to different lineages, the scientists involved say.
Their findings help to better understand the fundamental laws of leaf morphogenesis in plants — that is, the biological processes of formation and development of a leaf, from the appearance of the first founder cells to the acquisition of its final shape.
The study is the fruit of an international collaboration coordinated by UdeM biology professor Daniel Kierzkowski, a researcher in the Department of Biological Sciences' Institut de recherche en biologie végétale (IRBV).
His laboratory has established itself in recent years as a reference in plant morphogenesis, with work published in leading journals such as Cell, Nature Plants, and Nature Communications, focusing on the cellular dynamics that underlie the shape of plant organs.
"Mosses do have leaves in the common sense of the term, but not in the strict botanical sense," said Kierzkowski. “Mosses have small, flat, green appendages that resemble leaves and fulfill the same function: capturing light for photosynthesis. But technically, botanists call them phyllids rather than leaves, to distinguish them from the true leaves of vascular plants.”
