Protodermal Stem Cells in the Brachypodium Leaf

Protodermal stem cells are meristematic cells in the epidermal L1 layer at the base of the developing grass leaf. These stem cells have the capacity to produce all epidermal cell types of a grass leaf like the sealing and stabilizing pavement cells, gas-exchanging stomatal complexes, leaf-rolling bulliform cells and the functionally enigmatic but probably herbivore-deterring prickle hair cells and silica cells. As the ultimate barrier shielding the “inner” leaf physiology from “outer” abiotic and biotic stressors, the leaf epidermis is absolutely essential to plant survival. Yet, little is known regarding how protodermal stem cells terminate their pluripotent state and commit to distinct developmental trajectories to make the manifold cell types of the grass leaf epidermis. Here, we will use single-cell transcriptomics, developmental genetics and microscopy in the wild model grass Brachypodium distachyon to decipher how and where protodermal stem cells lose pluripotency and branch into distinct developmental trajectories. Together, this project will produce an unprecedented resolution of protodermal stem cell trajectories in B. distachyon, test the role of key transcription factor families regulating epidermal lineage trajectory commitment and spatially map where lineage commitment occurs in the meristematic zone of the grass leaf.