Phyllotaxis, which refers to the geometrical arrangement of lateral organs such as leaves, is a fundamental determinant of plant architecture. In flowering plants, phyllotaxis is established at the shoot apex within a multicellular tissue called the shoot apical meristem. Previous works have shown that both mechanical and biochemical signals contribute to phyllotaxis, including the structure and composition of cell walls and the phytohormone auxin.
In contrast with flowering plants, phyllotaxis in Physcomitrium patens is generated through the successive rotating divisions of a single apical cell, providing us a simple system to explore how similar biological patterns have evolved repeatedly during the course of plant diversification, and how the geometry of the apical cell and its derivatives, along with mechanical and biochemical cues shape the shoot.
Our work focuses on identifying the factors governing phyllotaxis in Physcomitrium. To explore the role of auxin in the establishment of the phyllotaxis, we analyzed mutants perturbed in auxin transport exhibiting abnormal shoot development. We developed a method to quantify phyllotaxis and using this technique, we observed perturbation in phyllotaxis in our mutants.
These mutants also showed a brittle phenotype indicating perturbed cell wall integrity. To test how auxin distribution affects cell wall, leading to phyllotaxis defects, we quantify the composition of cell wall in auxin-transport mutants. Taken together, our results suggest a convergent pivotal role for auxin and cell wall dynamics in shaping the phyllotaxis in moss.
Gratuit
Disciplines