Speaker: Zhen-Ming Pei, Duke University associate professor of biology in the Fitzpatrick Institute for Photonics

Title: "Ca²⁺-signaling-mediated sensors for hydrogen peroxide, salt and water"

Abstract: With the expansion in human activities and global environmental change, crops and plant ecosystems face increasingly challenges from their environment, including unfavorable temperatures, drought, and high salinity, among others. Terrestrial plant responses to and adaptations of environmental stresses are particularly crucial owning to their sessile lifestyle. It is well established that various environmental stresses trigger the increases in cytosolic free Ca²⁺ concentration ([Ca²⁺]_i) in plants. We have developed aequorin Ca²⁺ imaging-based forward genetic screens (called Ca²⁺ genetics) to isolate Arabidopsis mutants defective in [Ca²⁺]_i increases in response to environmental stresses. We have isolated osca1, moca1, and hyca1 mutants for osmotic stress, salt, and H₂O₂, respectively. OSCA1 is an osmotic stress-gated plasma membrane Ca²⁺ channel, which belongs to a gene family of 15 members. MOCA1 encodes a glucuronosyltransferase for glycosyl inositol phosphorylceramide (GIPC) sphingolipids in the plasma membrane. GIPCs provide Na⁺-binding sites and trigger Ca²⁺ signals upon Na⁺ binding, which is funneled to the SOS1/2/3 relay to extrude Na⁺ ions. The H₂O₂ sensor HPCA1 is an LRR receptor kinase, which is localized to the plasma membrane, and activated by H₂O₂ via covalent modification of extracellular cysteine residues. Identification of these long-sought receptors and sensors responsible for stimulus-triggered [Ca²⁺]_i increases could reveal novel insights into the Ca²⁺ machinery that integrate the signaling network throughout plants.

Host: Kyaw (Joe) Aung, genetics, development and cell biology assistant professor

Biography: Dr. Zhen-Ming Pei is an associate professor at Duke University. He is an interdisciplinary scientist who studies ion channels, signaling transduction, and stress perception mechanisms. Pei holds a master of science degree and a Ph.D. from Fudan University and Shanghai Institute of Plant Physiology, respectively, where he studied plant responses to abiotic and biotic stresses and was trained in plant physiology and electrophysiology. He did his postdoctoral work in ion channels and signaling transduction in plants at University of California, San Diego. Pei Lab at Duke maintains research interests in Ca²⁺-signaling-mediated environmental sensing in plant stress biology.