School of BioSciences - Theses
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ItemNo Preview AvailableMechanical control of Arabidopsis thaliana seed developmentBauer, Amélie ( 2023-10)Plant morphogenesis is the result of biochemical and mechanical interactions between cells and tissues. The implications of mechanical signals in the control of cellular processes in plants is well characterized, but their contribution to organ shape acquisition remains to be elucidated. Arabidopsis seeds, whose growth depends on mechanical interactions between two genetically and physically distinct compartments, the endosperm and the seed coat, allowed me to study the contribution of mechanical forces to the control of plant organ shape. During my thesis, I have shown that seeds exhibit two distinct growth phases, an initial phase of anisotropic growth followed by a phase of isotropic growth, and that this growth pattern depends on the mechanical properties of the outer integument of the seed coat. Thanks to the development of new technics of in vitro culture of developing seeds, I have shown that a specific population of cells in the outer integument controls the growth of the seed. Furthermore, I have demonstrated that mechanical signals control the anisotropic growth of these cells by organizing cortical microtubules so that cellulose can be deposited in the walls of the adaxial epidermis of the seed coat according to shape-driven stresses. Finally, I demonstrated that the transition from anisotropic to isotropic growth is not initiated by the differentiation of the load-bearing walls of the adaxial epidermis, but rather by a loss of microtubule organization in the outer walls of the integument of the abaxial epidermis.