Stomata are dispersed pores found in the epidermis of land plants that facilitate gas exchange for photosynthesis while minimizing water loss. Stomata are formed from progenitor cells, which execute a series of differentiation events and stereotypical cell divisions. The sequential activation of master regulatory basic-helix-loop-helix (bHLH) transcription factors controls the initiation, proliferation and differentiation of stomatal cells. Cell-cell communication mediated by secreted peptides,

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... receptor kinases, and downstream mitogenactivated kinase cascades enforces proper stomatal patterning, and an intrinsic polarity mechanism ensures asymmetric cell divisions. As we review here, recent studies have provided insights into the intrinsic and extrinsic factors that control stomatal development. These findings have also highlighted striking similarities between plants and animals with regards to their mechanisms of specialized cell differentiation. Lineage specification and progression during stomatal development Cell differentiation in many contexts is maintained by global transcriptional alterations mediated by a core network of transcription factors and epigenetic regulators. The bHLH family of TFs, in particular, appears to regulate lineage differentiation programs in various animal cell types. This includes the MyoD