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GDCB Seminar: "Uncovering mechanisms enabling environmentally responsive plant genomes in stomatal guard cells and roots"

Mar 7, 2024 - 11:00 AM
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Charles Seller, postdoctoral scholar at the University of California, San Diego

Speaker: Charles Seller, postdoctoral scholar at the University of California, San Diego

Title: "Uncovering mechanisms enabling environmentally responsive plant 
genomes in stomatal guard cells and roots"

Abstract: In plants, epidermal guard cells integrate and respond to numerous environmental signals to control stomatal pore apertures, thereby limiting water loss and regulating gas exchange. My research uses the guard cell as a model cell system for investigating the mechanisms that connect environmental conditions to plant genome structure and activity. The hormone abscisic acid (ABA), a key regulator of plant responses to drought stress, and changes in atmospheric CO2 (carbon dioxide) concentration are signals that control stomatal aperture size, but whether these signals also regulate genome packaging into chromatin is unknown. Using cell-type specific genomic approaches we discovered that ABA triggers rapid and persistent remodeling of chromatin accessibility in Arabidopsis guard cells, roots, and mesophyll cells. Our experiments identified thousands of cis-regulatory regions deployed during the response to ABA in guard cells and revealed clear patterns of cell-type specificity. By isolating and analyzing guard cells from higher order mutant plants we identified the specific transcription factors responsible for controlling ABA-mediated chromatin dynamics. Furthermore, we show that changes in atmospheric CO2 concentration (both reduced and elevated CO2) induce programs of chromatin remodeling in guard cells that are completely distinct from those triggered by ABA. I will also discuss ongoing studies aimed at resolving the 3D architecture of the guard cell genome and determining its relationship to stomatal function. Our results support a model wherein chromatin structure acts as a platform where different physiological signals are integrated in the guard cell leading to long-term and protective adjustments to stomatal function. 

Host: Geetu Tuteja, GDCB associate professor