Unraveling the molecular network that drives cell growth in plants
Plants differ strikingly from animals by the almost total absence of cell migration in their development. Plants build their bodies using a hydrostatic skeleton that consists of pressurized cells encased by a cell wall. Consequently, plant cells cannot migrate and must sculpture their bodies by orientation of cell division and precise regulation of cell growth. Cell growth depends on the balance between internal cell pressure – turgor, and strength of the cell wall. Cell growth is under a strict developmental control, which is exemplified in the Arabidopsis thaliana root tip, where massive cell elongation occurs in a defined spatio-temporal developmental window. Despite the immobility of their cells, plant organs move to optimize light and nutrient acquisition and to orient their bodies along the gravity vector. These movements depend on differential regulation of cell elongation across the organ, and on response to the phytohormone auxin. Even though the control of cell growth is in the epicenter of plant development, protein networks steering the developmental growth onset, coordination and termination remain elusive. Similarly, although auxin is the central regulator of growth, the molecular mechanism of its effect on root growth is unknown. In this project, I will establish a unique microscopy setup for high spatio-temporal resolution live-cell imaging equipped with a microfluidic lab-on-chip platform optimized for growing roots, to enable analysis and manipulation of root growth physiology. I will use developmental gradients in the root to discover genes that steer cellular growth, by correlating transcriptome profiles of individual cell types with the cell size. In parallel, I will exploit the auxin effect on root to unravel molecular mechanisms that control cell elongation. Finally, I am going to combine the live-cell imaging methodology with the gene discovery approaches to chart a dynamic spatio-temporal physiological map of a growing Arabidopsis root.