Speaker: Sally Assmann, Waller Professor of Biology at Pennsylvania State University Huck Institutes of the Life Sciences

Title: "Heterotrimeric G protein signaling in guard cells"

Abstract: Heterotrimeric G proteins are molecular switches comprised of three subunits: Gα, Gβ, and Gγ. In the canonical, mammannlian model of G protein signaling, ligand-binding of a G protein-coupled receptor (GPCR) triggers dissociation of Gα from Gβγ, with both resultant entities capable of interacting with downstream protein partners to propagate the signal. The model plant species, Arabidopsis thaliana, has one canonical Gα subunit (GPA1), three non-canonical Gα subunits named extra-large G proteins (XLG1, XLG2, XLG3), one Gβ subunit (AGB1), and three Gγ subunits (AGG1, AGG2, AGG3). In plants as in all eukaryotes, G proteins control myriad developmental and cell signaling processes. In guard cells, a specialized plant cell type, we have shown that G proteins regulate ion channels and thus cell volume in response to abscisic acid (ABA), a plant hormone produced in response to drought and other abiotic stresses. We have recently identified key protein partners residing between G proteins and ion channels in this signaling cascade. While in mammalian systems the GPCRs are seven-transmembrane-domain proteins, emerging evidence implicates receptor-like kinases (RLKs) as plant GPCRs. Our preliminary data implicate RLKs and XLG-containing heterotrimers as components of biotic (pathogen) sensing in guard cells.

Host: Michelle Guo, Department of Genetics, Development and Cell Biology assistant professor