Fluctuating auxin response gradients determine pavement cell-shape acquisition

Puzzle-shaped pavement cells provide a powerful model system to investigate the cellular and subcellular processes underlying com- plex cell-shape determination in plants. To better understand pavement cell-shape acquisition and the role of auxin in this pro- cess, we focused on the spirals of young stomatal lineage ground cells of Arabidopsis leaf epidermis. The predictability of lobe forma- tion in these cells allowed us to demonstrate that the auxin response gradient forms within the cells of the spiral and fluctuates based on the particular stage of lobe development. We revealed that specific localization of auxin transporters at the different membranes of these young cells changes during the course of lobe formation, sug- gesting that these fluctuating auxin response gradients are orches- trated via auxin transport to control lobe formation and determine pavement cell shape.