Carlos O. Miller Lecture Series

Upcoming lecture

Dominique Bergmann
Professor of Biology
Stanford University

Adjusting the valves: Optimizing stomatal development with systemic cues

Thursday, August 23, 2018
4 to 5:00 p.m.
Myers Hall 130

Abstract: Plants exhibit remarkable developmental plasticity in response to changes in nutritional status or the environment.

We use the Arabidopsis stomatal lineage as our model to understand how information from a variety of local and distant sources is integrated into developmental decisions. The stomatal lineage creates stomata, microscopic cellular valves that are essential for gas-exchange between the plant and environment; however, it also features a stem-cell-like precursor stage that can be modulated to enable plants to make bigger or smaller leaves and more or fewer stomata as appropriate for the environment. SPEECHLESS (SPCH) is a transcription factor required for the stem-cell divisions of the stomatal lineage.

We have recently uncovered a regulatory circuit involving the hormone cytokinin (CK) and SPCH that modulates stomatal stem-cell proliferation. This regulatory circuit dictates how often cells divide and, moreover, influences the type of asymmetric divisions made in the stomatal lineage. Live cell imaging of CK reporters revealed a spatially and temporally dynamic landscape of CK response during stomatal lineage progression, and we can show that this landscape is sculpted by SPCH-dependent expression of CK-related signaling peptides and negative-acting regulatory elements. This hormone system works orthogonally to stomatal-specific peptide-receptor-MAPK signaling previously described to regulate cell fate, cell polarity, and cell patterning, thereby allowing plants to conditionally modulate leaf anatomy yet maintain appropriate tissue patterning. This SPCH-CK feedback loop, together with other signaling pathways, contributes to the extraordinary flexibility in growth and development we see in plants.

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