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Direct roles of SPEECHLESS in the specification of stomatal self-renewing cells

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Science  26 Sep 2014:
Vol. 345, Issue 6204, pp. 1605-1609
DOI: 10.1126/science.1256888

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A complex network makes simple pores

Stomata, the pores found on the surface of plant leaves, form at intervals from stem cells. Development of stomata is controlled by the SPEECHLESS transcription factor. Lau et al. surveyed the genes that SPEECHLESS itself controls. Targets include genes involved in hormone signaling, control of cell proliferation, and the specification of asymmetric cell fates. Despite the apparent simplicity of a single pore, the genetic network that generates that pore is anything but simple.

Science, this issue p. 1605

Abstract

Lineage-specific stem cells are critical for the production and maintenance of specific cell types and tissues in multicellular organisms. In Arabidopsis, the initiation and proliferation of stomatal lineage cells is controlled by the basic helix-loop-helix transcription factor SPEECHLESS (SPCH). SPCH-driven asymmetric and self-renewing divisions allow flexibility in stomatal production and overall organ growth. How SPCH directs stomatal lineage cell behaviors, however, is unclear. Here, we improved the chromatin immunoprecipitation (ChIP) assay and profiled the genome-wide targets of Arabidopsis SPCH in vivo. We found that SPCH controls key regulators of cell fate and asymmetric cell divisions and modulates responsiveness to peptide and phytohormone-mediated intercellular communication. Our results delineate the molecular pathways that regulate an essential adult stem cell lineage in plants.

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